In JoVE (1)

Other Publications (114)

Articles by Michael Patterson in JoVE

Other articles by Michael Patterson on PubMed

Error Assessment of a Wavelength Tunable Frequency Domain System for Noninvasive Tissue Spectroscopy

Journal of Biomedical Optics. Jul, 1996  |  Pubmed ID: 23014731

Abstract not available.

Azide and Cyanide Displacements Via Hypervalent Silicate Intermediates

The Journal of Organic Chemistry. Apr, 1999  |  Pubmed ID: 11674417

Hypervalent azido- and cyanosilicate derivatives, prepared in situ by the reaction of trimethylsilyl azide or trimethylsilyl cyanide, respectively, with tetrabutylammonium fluoride, are effective sources of nucleophilic azide or cyanide. Primary and secondary alkyl halides and sulfonates undergo rapid and efficient azide or cyanide displacement in the absence of phase transfer catalysts with the silicate derivatives. Application of these reagents to the stereoselective synthesis of glycosyl azide derivatives is reported.

Haemoglobin Oxygenation of a Two-layer Tissue-simulating Phantom from Time-resolved Reflectance: Effect of Top Layer Thickness

Physics in Medicine and Biology. Jan, 2002  |  Pubmed ID: 11837612

A dual wavelength time-resolved reflectance system was developed for monitoring haemoglobin saturation noninvasively. At each wavelength, the time-resolved reflectance data were fitted to a diffusion model of light propagation in a homogeneous, semi-infinite medium to yield the absolute scattering and absorption coefficients. The absorption coefficients were then used to calculate haemoglobin saturation. A two-layer phantom containing human erythrocytes in a scattering solution in the bottom layer was used to study system performance under more realistic conditions. The top layer was chosen to simulate either skin or fat and the oxygenation of the bottom layer, which corresponded to muscle, was controlled. The thickness of the fat layer was varied from 1.5 to 10 mm to investigate the effects of increasing the top layer thickness. These results, obtained with the simple diffusion model, were compared with simultaneous measurements of oxygenation made directly in the bottom layer. Errors in estimating haemoglobin saturation with this method ranged from 5-11% depending on the thickness of the top layer and its optical properties.

Proposed Tenets of Osteopathic Medicine and Principles for Patient Care

The Journal of the American Osteopathic Association. Feb, 2002  |  Pubmed ID: 11866391

Relationship Between MTHPC Fluorescence Photobleaching and Cell Viability During in Vitro Photodynamic Treatment of DP16 Cells

Photochemistry and Photobiology. Mar, 2002  |  Pubmed ID: 11950095

An implicit dosimetric model has been proposed in which biological damage caused by photodynamic therapy (PDT) is monitored through the decrease in sensitizer fluorescence during treatment. To investigate this, in vitro experiments were performed in which DP16 cells were incubated in meta-tetra(hydroxyphenyl)chlorin (mTHPC) and then irradiated with 514 nm light. Photosensitizer concentration, fluence rate and oxygenation were independently controlled and monitored during the treatment. Fluorescence of mTHPC was continuously monitored via a charge-coupled device-coupled spectrometer during treatment and, at selected fluence levels, cell viability was determined using a trypan blue exclusion assay. The relationship of cell viability to normalized fluorescence was obtained for the different treatment conditions. The relationship was independent of cell medium oxygenation, treatment fluence rate and sensitizer incubation concentration except at a high mTHPC concentration (4 microg/mL). This relationship suggests that fluorescence bleaching may be used to predict mTHPC PDT damage in vitro.

Direct Near-infrared Luminescence Detection of Singlet Oxygen Generated by Photodynamic Therapy in Cells in Vitro and Tissues in Vivo

Photochemistry and Photobiology. Apr, 2002  |  Pubmed ID: 12003128

Singlet oxygen (1O2) is believed to be the major cytotoxic agent involved in photodynamic therapy (PDT). Measurement of 1O2 near-infrared (NIR) luminescence at 1270 nm in biological environments is confounded by the strongly reduced 1O2 lifetime and probably has never been achieved. We present evidence that this is now possible, using a new NIR-sensitive photomultiplier tube. Time-resolved 1O2 luminescence measurements were made in various solutions of aluminum tetrasulphonated phthalocyanine (AlS4Pc) and Photofrin. Measurements were also performed on suspensions of leukemia cells incubated with AlS4Pc, and a true intracellular component of the 1O2 signal was clearly identified. Time-resolved analysis showed a strongly reduced 1O2 lifetime and an increased photosensitizer triplet-state lifetime in the intracellular component. In vivo measurements were performed on normal skin and liver of Wistar rats sensitized with 50 mg/kg AlS4Pc. In each case, a small but statistically significant spectral peak was observed at 1270 nm. The 1O2 lifetime based on photon count rate measurements at 1270 nm was 0.03-0.18 micros, consistent with published upper limits. We believe that these are the first direct observations of PDT-generated intracellular and in vivo 102. The detector technology provides a new tool for PDT research and possibly clinical use.

Ethical Dilemmas and Human Rights Considerations Arising from the Evaluation of a Smoking Policy in a Health Promoting Setting

International Journal of Environmental Health Research. Sep, 2002  |  Pubmed ID: 12396527

One of the key challenges in managing the Health Promoting Workplace is the development of an effective policy for the control of environmental tobacco smoke (ETS). This paper explores the ethical consequences raised when the implementation of such a policy was evaluated in a large multi-campus university. In a three-stage evaluation, the first stage involved a qualitative enquiry with the Health and Safety Committee to obtain the management perspective on the working of the policy. A survey of the perception of the ETS policy and smoking behaviours with a representative sample of staff and students constituted the second stage. In the final stage the Health and Safety Committee was engaged with the findings of stages 1 and 2 to develop a response to the evaluation. The ethical implications which arise from this evaluation centre, firstly, on the underlying reasons for undertaking an evaluation. Secondly, consideration is given to the consequences of applying utilitarian principles to smoking policy for the minority who smoke and thus find their work or study patterns affected by a smoking ban. Such a ban limits their autonomy and while it may be helpful (beneficent) in terms of their longer-term physical health, it may have harmful (maleficent) effects on their psychological wellbeing and the potential for negative consequences if they choose to contravene the ban on smoking. The implications of addressing this situation are explored.

Distinct Distribution of Specific Members of Protein 4.1 Gene Family in the Mouse Nephron

Kidney International. Apr, 2003  |  Pubmed ID: 12631349

Protein 4.1 is an adapter protein that links the actin cytoskeleton to various transmembrane proteins. These 4.1 proteins are encoded by four homologous genes, 4.1R, 4.1G, 4.1N, and 4.1B, which undergo complex alternative splicing. Here we performed a detailed characterization of the expression of specific 4.1 proteins in the mouse nephron.

Stimulation of Human Colonic Epithelial Cells by Leukemia Inhibitory Factor is Dependent on Collagen-embedded Fibroblasts in Organotypic Culture

FASEB Journal : Official Publication of the Federation of American Societies for Experimental Biology. Jun, 2003  |  Pubmed ID: 12692084

The colonic epithelium undergoes a continuous cycle of proliferation, differentiation, and apoptosis. To characterize factors important for colonic homeostasis and its dysregulation, human fetal colonic epithelial cells were isolated and seeded on a collagen type I matrix with embedded colonic fibroblasts. The epithelial cells rapidly spread from clusters and proliferated, and within 3 days, a columnar layer of polarized epithelium surrounded the surface of the constricted collagen matrix. The polarized enterocytes developed brush borders, tight junctions and desmosomes, and goblet and enteroendocrine cells were present. A balance of growth and differentiation was maintained for several weeks in the presence of collagen-embedded fibroblasts and a complex mixture of growth factors. Leukemia inhibitory factor (LIF) was critical for proliferation of enterocytes and inhibited expression of the differentiation marker carbonic anhydrase II. In the presence of LIF, the relative number of goblet cells remained stable, whereas enteroendocrine relative cell number declined. LIF-stimulated epithelial cells remained dependent on the presence of fibroblasts in the matrix. In combination with stem cell factor and endothelin 3, LIF induced formation of disorganized structures of stratified and semi-stratified cells, suggesting that the homeostatic balance in the normal human colon requires cooperation with differentiation-inducing factors.

Predictors of Successful Relationships in a Peer Support Program for Alzheimer's Caregivers

American Journal of Alzheimer's Disease and Other Dementias. Mar-Apr, 2003  |  Pubmed ID: 12708227

This study explores the role of similarity in the success of peer support relationships in an intervention program for dementia caregivers. Hypothesized predictors of successful matches included structural similarity between partners (e.g., in age, education), appraisal similarity (e.g., in satisfaction with support for caregiving), and psychological similarity (e.g., in psychological well-being). Contrary to expectations, no relationship between these types of similarity and the success of the match were found, but effects were found for dissimilar pairs on several characteristics. The findings suggest: 1) that what really makes a difference for successful peer support is sharing the stressful but also rewarding experience of caregiving; and 2) that program planners do not need to develop extensive matching criteria.

MHC-based Fiber Type and E-C Coupling Characteristics in Mechanically Skinned Muscle Fibers of the Rat

American Journal of Physiology. Cell Physiology. Jun, 2003  |  Pubmed ID: 12734106

In this study, we investigated whether the previously established differences between fast- and slow-twitch single skeletal muscle fibers of the rat, in terms of myosin heavy chain (MHC) isoform composition and contractile function, are also detectable in excitation-contraction (E-C) coupling. We compared the contractile responsiveness of electrophoretically typed, mechanically skinned single fibers from the soleus (Sol), the extensor digitorum longus (EDL), and the white region of the sternomastoid (SM) muscle to t-system depolarization-induced activation. The quantitative parameters assessed were the amplitude of the maximum depolarization-induced force response (DIFR(max); normalized to the maximum Ca(2+)-activated force in that fiber) and the number of responses elicited until the force declined by 75% of DIFR(max) (R-D(75%)). The mean DIFR(max) values for type IIB EDL and type IIB SM fibers were not statistically different, and both were greater than the mean DIFR(max) for type I Sol fibers. The mean R-D(75%) for type IIB EDL fibers was greater than that for type I Sol fibers as well as type IIB SM fibers. These data suggest that E-C coupling characteristics of mechanically skinned rat single muscle fibers are related to MHC-based fiber type and the muscle of origin.

Quantification of Fluorophore Concentration in Tissue-simulating Media by Fluorescence Measurements with a Single Optical Fiber

Applied Optics. May, 2003  |  Pubmed ID: 12737480

Quantifying fluorescent compounds in turbid media such as tissue is made difficult by the effects of multiple scattering and absorption of the excitation and emission light. The approach that we used was to measure fluorescence using a single 200-microm optical fiber as both the illumination source and the detector. Fluorescence of aluminum phthalocyanine tetrasulfonate (AlPcS4) was measured over a wide range of fluorophore concentrations and optical properties in tissue-simulating phantoms. A root-mean-square accuracy of 10.6% in AlPcS4 concentration was attainable when fluorescence was measured either interstitially or at the phantom surface. The individual effects of scattering, absorption, and the scattering phase function on the fluorescence signal were also studied by experiments and Monte Carlo simulations.

Oxyntomodulin Suppresses Appetite and Reduces Food Intake in Humans

The Journal of Clinical Endocrinology and Metabolism. Oct, 2003  |  Pubmed ID: 14557443

Oxyntomodulin (OXM) is released from the gut postprandially, in proportion to energy intake, and circulating levels of OXM are elevated in several conditions associated with anorexia. Central injection of OXM reduces food intake and weight gain in rodents, suggesting that OXM signals food ingestion to hypothalamic appetite-regulating circuits. We investigated the effect of iv OXM (3.0 pmol/kg.min) on appetite and food intake in 13 healthy subjects (body mass index, 22.5 +/- 0.9 kg/m(2)) in a randomized, double-blind, placebo-controlled, cross-over study. Infusion of OXM significantly reduced ad libitum energy intake at a buffet meal (mean decrease, 19.3 +/- 5.6%; P < 0.01) and caused a significant reduction in scores for hunger. In addition, cumulative 12-h energy intake was significantly reduced by infusion of OXM (mean decrease, 11.3 +/- 6.2%; P < 0.05). OXM did not cause nausea or affect food palatability. Preprandial levels of the appetite-stimulatory hormone, ghrelin, were significantly suppressed by OXM (mean reduction, 44 +/- 10% of postprandial decrease; P < 0.0001). Elevated levels of endogenous OXM associated with disorders of the gastrointestinal tract may contribute to anorexia.

In Vitro Tests of the Validity of Singlet Oxygen Luminescence Measurements As a Dose Metric in Photodynamic Therapy

Cancer Research. Nov, 2003  |  Pubmed ID: 14633731

Singlet oxygen ((1)O(2)) is widely believed to be the major cytotoxic agent involved in photodynamic therapy (PDT). We showed recently that measurement of the weak near infrared luminescence of (1)O(2) is possible in cells in vitro and tissues in vivo. Here, we investigated the relationship between the integrated luminescence signal and the in vitro PDT response of AML5 leukemia cells sensitized with aminolevulinic acid-induced protoporphyrin IX (PpIX). Sensitized cell suspensions were irradiated with pulsed 523 nm laser light at average fluence rates of 10, 25, or 50 mWcm(-2) and, (1)O(2) luminescence measurements were made throughout the treatment. Cell survival was measured with either propidium iodide-labeled flow cytometry or colony-forming assay. The PpIX concentration in the cells, the photobleaching, and the pO(2) in the cell suspensions were also monitored. There were large variations in cell survival and (1)O(2) generation in different experiments due to different controlled treatment parameters (fluence and fluence rate) and other uncontrolled factors (PpIX synthesis and oxygenation). However, in all of the cases, cell kill correlated strongly with the cumulative (1)O(2) luminescence and allowed direct estimation of the (1)O(2) per cell required to achieve a specific level of cell kill. This study supports the validity and potential utility of (1)O(2) luminescence measurement as a dosimetric tool for PDT, as well as confirming the likely role of (1)O(2) in porphyrin-based PDT.

The Use of Spatially Resolved Fluorescence and Reflectance to Determine Interface Depth in Layered Fluorophore Distributions

Physics in Medicine and Biology. Nov, 2003  |  Pubmed ID: 14653556

The possibility of using spatially resolved fluorescence and reflectance measurements to recover tissue optical properties, fluorophore concentration and the thickness of a superficial layer in a two-layer geometry was investigated. A diffusion theory model was used to fit reflectance and fluorescence data generated using Monte Carlo simulations or experimentally obtained using tissue-simulating phantoms. Initial analysis fitting diffusion theory generated data suggested that it should be possible to recover all parameters from a single set of spatially resolved fluorescence and reflectance measurements. However, when Monte Carlo or experimental data were fitted the results were less impressive. Overall, it was shown that there is a strong coupling between interface depth, fluorophore concentration and tissue absorption, especially at larger depths. The recovery of all input parameters from a single set of spatially resolved measurements was limited to interface depths less than 3 mm, which is a reasonable range for measuring fluorophore in skin. When the tissue optical properties and fluorophore concentrations were known, then the interface depth could be monitored with good accuracy in simulated serial measurements. These results may also point to deficiencies in the diffusion theory model that introduce significant errors in the fitted results.

Clipped Tube Fenestration After Extracardiac Fontan Allows for Simple Transcatheter Coil Occlusion

The Annals of Thoracic Surgery. Dec, 2003  |  Pubmed ID: 14667614

Expensive devices are increasingly used to close a patent fenestration after a modified Fontan operation. We report our 5-year institutional experience of clipped tube fenestration after extracardiac Fontan operation, which allows for simple transcatheter coil occlusion.

Measurement of Fluorophore Concentrations and Fluorescence Quantum Yield in Tissue-simulating Phantoms Using Three Diffusion Models of Steady-state Spatially Resolved Fluorescence

Physics in Medicine and Biology. Dec, 2003  |  Pubmed ID: 14727757

Steady-state diffusion theory models of fluorescence in tissue have been investigated for recovering fluorophore concentrations and fluorescence quantum yield. Spatially resolved fluorescence, excitation and emission reflectance Carlo simulations, and measured using a multi-fibre probe on tissue-simulating phantoms containing either aluminium phthalocyanine tetrasulfonate (AlPcS4), Photofrin meso-tetra-(4-sulfonatophenyl)-porphine dihydrochloride The accuracy of the fluorophore concentration and fluorescence quantum yield recovered by three different models of spatially resolved fluorescence were compared. The models were based on: (a) weighted difference of the excitation and emission reflectance, (b) fluorescence due to a point excitation source or (c) fluorescence due to a pencil beam excitation source. When literature values for the fluorescence quantum yield were used for each of the fluorophores, the fluorophore absorption coefficient (and hence concentration) at the excitation wavelength (mu(a,x,f)) was recovered with a root-mean-square accuracy of 11.4% using the point source model of fluorescence and 8.0% using the more complicated pencil beam excitation model. The accuracy was calculated over a broad range of optical properties and fluorophore concentrations. The weighted difference of reflectance model performed poorly, with a root-mean-square error in concentration of about 50%. Monte Carlo simulations suggest that there are some situations where the weighted difference of reflectance is as accurate as the other two models, although this was not confirmed experimentally. Estimates of the fluorescence quantum yield in multiple scattering media were also made by determining mu(a,x,f) independently from the fitted absorption spectrum and applying the various diffusion theory models. The fluorescence quantum yields for AlPcS4 and TPPS4 were calculated to be 0.59 +/- 0.03 and 0.121 +/- 0.001 respectively using the point source model, and 0.63 +/- 0.03 and 0.129 +/- 0.002 using the pencil beam excitation model. These results are consistent with published values.

Peripheral Oxyntomodulin Reduces Food Intake and Body Weight Gain in Rats

Endocrinology. Jun, 2004  |  Pubmed ID: 15001546

Oxyntomodulin (OXM) is a circulating gut hormone released post prandially from cells of the gastrointestinal mucosa. Given intracerebroventricularly to rats, it inhibits food intake and promotes weight loss. Here we report that peripheral (ip) administration of OXM dose-dependently inhibited both fast-induced and dark-phase food intake without delaying gastric emptying. Peripheral OXM administration also inhibited fasting plasma ghrelin. In addition, there was a significant increase in c-fos immunoreactivity, a marker of neuronal activation, in the arcuate nucleus (ARC). OXM injected directly into the ARC caused a potent and sustained reduction in refeeding after a fast. The anorectic actions of ip OXM were blocked by prior intra-ARC administration of the glucagon-like peptide-1 (GLP-1) receptor antagonist, exendin(9-39), suggesting that the ARC, lacking a complete blood-brain barrier, could be a potential site of action for circulating OXM. The actions of ip GLP-1, however, were not blocked by prior intra-ARC administration of exendin(9-39), indicating the potential existence of different OXM and GLP-1 pathways. Seven-day ip administration of OXM caused a reduction in the rate of body weight gain and adiposity. Circulating OXM may have a role in the regulation of food intake and body weight.

Physics in Medicine and Biology Top Ten

Physics in Medicine and Biology. Feb, 2004  |  Pubmed ID: 15005171

Safety of Modified Radical Neck Dissection for Differentiated Thyroid Carcinoma

The Laryngoscope. Mar, 2004  |  Pubmed ID: 15091209

The management of cervical metastases from differentiated thyroid carcinoma (DTC) remains controversial. Most surgeons perform a neck dissection (ND) for clinically apparent disease. The extent of nodal dissection varies from regional to comprehensive. Morbidity from ND in the setting of DTC remains high, particularly when performed in the setting of a thyroidectomy (TT). To determine complications from ND for DTC, we retrospectively reviewed our surgical experience of modified radical neck dissection for nodal metastases.

Compression of Mediastinal Structures Treated by Extra-anatomic Bypass Grafting

Journal of Cardiac Surgery. Jul-Aug, 2004  |  Pubmed ID: 15245466

Extra-anatomic bypass grafts have been used to treat complex and recurrent forms of coarctation of the aorta. Here we describe the use of an extra-anatomic bypass graft from the ascending to supraceliac aorta to treat an unusual complication of compression of mediastinal structures caused by a bucket handle graft.

Patterns of Lateral Neck Metastasis in Papillary Thyroid Carcinoma

Archives of Otolaryngology--head & Neck Surgery. Jul, 2004  |  Pubmed ID: 15262763

Although lymphatic metastasis does not affect overall survival for patients with differentiated thyroid carcinoma, locoregional control can be improved with cervical lymphadenectomy. The major morbidity of neck dissection (ND) for the management of regional metastases is spinal accessory (cranial nerve XI) dysfunction. To avoid this complication, some surgeons have advocated a limited ND.

Photobleaching Kinetics of Photofrin in Vivo and in Multicell Tumour Spheroids Indicate Two Simultaneous Bleaching Mechanisms

Physics in Medicine and Biology. Nov, 2004  |  Pubmed ID: 15584523

We present a detailed investigation of Photofrin photobleaching and photoproduct accumulation. Fisher rats were sensitized with 10 mg kg(-1) Photofrin and irradiated 24 h later with 514 nm light at 5 or 100 mW cm(-2). Fluorescence spectra were collected from the skin throughout treatment, and sensitizer bleaching and fluorescent photoproduct formation were quantified using spectral analysis. Photofrin bleaching was slightly more rapid at the higher irradiance under these conditions. However, accumulation of photoproduct was significantly enhanced at lower irradiance. To interpret these unexpected findings, we developed a new mathematical model in which reactions between singlet oxygen (1O2) and the photosensitizer and reactions between the sensitizer triplet and biological targets are both allowed to contribute to bleaching. Predictions of this model were tested in experiments performed on EMT6 spheroids sensitized with concentrations of 2.5, 10 and 30 microg mL(-1) Photofrin and subjected to PDT. Photofrin bleaching and photoproduct formation in these spheroids were measured using confocal fluorescence spectroscopy. In qualitative agreement with the mixed-mechanism model predictions, at the highest drug concentration Photofrin bleaching was more efficient via 1O2 reactions, while at the lowest concentration triplet reactions were more efficient. At all concentrations, photoproduct accumulation was greater under conditions of abundant oxygen.

Calculation of Singlet Oxygen Dose from Photosensitizer Fluorescence and Photobleaching During MTHPC Photodynamic Therapy of MLL Cells

Photochemistry and Photobiology. Jan-Feb, 2005  |  Pubmed ID: 15469385

Predicting the therapeutic outcome of photodynamic therapy (PDT) requires knowledge of the amount of cytoxic species generated. An implicit approach to assessing PDT efficacy has been proposed where changes in photosensitizer (PS) fluorescence during treatment are used to predict treatment outcome. To investigate this, in vitro experiments were performed in which Mat-LyLu cells were incubated in meta-tetra(hydroxyphenyl)chlorin (mTHPC) and then irradiated with 652 nm light. PS concentration, fluence rate and oxygenation were independently controlled and monitored during the treatment. Fluorescence of mTHPC was monitored during treatment and, at selected fluence levels, cell viability was determined using a colony-formation assay. Singlet oxygen dose was calculated using four different models and was compared with cell survival. For the dose metric based on singlet oxygen-mediated PS photobleaching, a universal relationship between cell survival and singlet oxygen dose was found for all treatment parameters. Analysis of the concentration dependence of bleaching suggests that the lifetime of singlet oxygen within the cell is 0.05-0.25 micros. Generation of about 9 x 10(8) molecules of singlet oxygen per cell reduces the surviving fraction by 1/e.

Impaired Circulating Glucagon-like Peptide-1 Response to Oral Glucose in Women with Previous Gestational Diabetes

Clinical Endocrinology. Jan, 2005  |  Pubmed ID: 15638870

Women with previous gestational diabetes (pGDM) are at risk of developing Type 2 diabetes. Glucagon-like peptide-1 (GLP-1) potentiates the insulin response to oral glucose, and its secretion is diminished in Type 2 diabetes. The aim of the study was to see if decreased GLP-1 secretion might be an early abnormality in the progression to Type 2 diabetes and would therefore be diminished in women with pGDM.

Characterization of Ghrelin-like Immunoreactivity in Human Plasma

The Journal of Clinical Endocrinology and Metabolism. Apr, 2005  |  Pubmed ID: 15657369

Ghrelin is a gastric peptide hormone that has an important role in appetite control and GH release. Circulating ghrelin levels are inversely correlated with body mass index and postprandially suppressed. However, the molecular form of circulating ghrelin has not been fully characterized. We studied circulating ghrelin-like immunoreactivity (Ghr-LI) using three RIAs: one specific for only the active, acylated ghrelin (antibody G0-1) and the other two detecting both active and inactive, des-acylated ghrelin (antibody SC and the commercially available Phoenix Pharmaceuticals assay). Plasma ghrelin levels were measured in healthy subjects after a test breakfast (n = 8). Ghr-LI detected by SC and the commercial assay fell significantly at 90 and 120 min post meal (P < 0.01). G0-1 Ghr-LI decreased significantly at 30 min (P < 0.05) post meal and had returned to basal levels at 90 min. Gel permeation chromatography identified three Ghr-LI peaks in plasma. Two G0-1 Ghr-LI peaks with a molecular weight much larger than ghrelin peptide were detected. Only one Ghr-LI peak was detected by the SC and commercial RIA, at the same elution position as synthetic des-acylated ghrelin. These results suggest that the majority of circulating acylated ghrelin is bound to larger molecules, whereas des-acylated ghrelin circulates as free peptide. Assays measuring specific forms of ghrelin may be more useful in determining its physiological role than those that detect both acylated and des-acylated forms.

Fasting and Postprandial Hyperghrelinemia in Prader-Willi Syndrome is Partially Explained by Hypoinsulinemia, and is Not Due to Peptide YY3-36 Deficiency or Seen in Hypothalamic Obesity Due to Craniopharyngioma

The Journal of Clinical Endocrinology and Metabolism. May, 2005  |  Pubmed ID: 15687345

The cause of the unique elevation in fasting plasma levels of the orexigenic gastric hormone ghrelin in many patients with Prader-Willi syndrome (PWS) is unclear. We measured fasting and postprandial plasma ghrelin in nonobese (n = 16 fasting and n = 8 postprandial) and obese non-PWS adults (n = 16 and 9), adults with genetically confirmed PWS (n = 26 and 10), and patients with hypothalamic obesity from craniopharyngioma tumors (n = 9 and 6). We show that 1) plasma ghrelin levels decline normally after food consumption in PWS, but there is still fasting and postprandial hyperghrelinemia relative to the patient's obesity (2.0-fold higher fasting ghrelin, 1.8-fold higher postprandial ghrelin, adjusting for percentage of body fat); 2) the fasting and postprandial hyperghrelinemia in PWS appears to be at least partially, but possibly not solely, explained by the concurrent relative hypoinsulinemia and preserved insulin sensitivity for the patient's obesity (residual 1.3- to 1.6-fold higher fasting ghrelin, 1.2- to 1.5-fold higher postprandial ghrelin in PWS, adjusting for insulin levels or homeostasis model assessment of insulin resistance); 3) hyperghrelinemia and hypoinsulinemia are not found in craniopharyngioma patients with hypothalamic obesity, and indeed, these patients have relative hyperinsulinemia for their obesity; and 4) there is no deficiency of the anorexigenic intestinal hormone peptide YY(3-36) in PWS contributing to their hyperghrelinemia.

Imaging of Photodynamically Generated Singlet Oxygen Luminescence in Vivo

Photochemistry and Photobiology. Jul-Aug, 2005  |  Pubmed ID: 15865471

We describe a novel scanning-laser system for imaging type-II photodynamically generated singlet oxygen (1O2[1delta(g)]) luminescence and demonstrate it in vivo in an intradermal tumor model in mice. We verify the strong oxygen-dependence of the signal and show that the images are near the practical resolution limit.

Subcutaneous Ghrelin Enhances Acute Food Intake in Malnourished Patients Who Receive Maintenance Peritoneal Dialysis: a Randomized, Placebo-controlled Trial

Journal of the American Society of Nephrology : JASN. Jul, 2005  |  Pubmed ID: 15888560

Anorexia and malnutrition confer significant morbidity and mortality to patients with end-stage kidney disease but are resistant to therapy. The aim of this study was to determine whether subcutaneous administration of ghrelin, an appetite-stimulating gut hormone, could enhance food intake in patients who are receiving maintenance peritoneal dialysis and have evidence of malnutrition. The principal outcome measure was energy intake during a measured study meal. Secondary outcome measures were BP and heart rate and 3-d food intake after intervention. Nine peritoneal dialysis patients with mild to moderate malnutrition (mean serum albumin 28.6 +/- 5.0 g/L, total cholesterol 4.4 +/- 0.6 mmol/L, subjective global assessment score of 5.7 +/- 1.7) were given subcutaneous ghrelin (3.6 nmol/kg) and saline placebo in a randomized, double-blind, crossover protocol. Administration of subcutaneous ghrelin significantly increased the group mean absolute energy intake, compared with placebo, during the study meal (690 +/- 190 versus 440 +/- 250 kcal; P = 0.0062). When expressed as proportional energy increase for each individual, ghrelin administration resulted in immediate doubling of energy intake (204 +/- 120 versus 100%; P = 0.0319). Administration of ghrelin maintained a nonsignificant increase in energy intake over 24 h after intervention (2009 +/- 669 versus 1579 +/- 330 kcal) and was not followed by subsequent underswing (1790 +/- 370 versus 1670 +/- 530 and 1880 +/- 390 versus 1830 +/- 530 kcal on days 2 and 3, respectively). Ghrelin administration resulted in a significant fall in mean arterial BP (P = 0.0030 by ANOVA). There were no significant adverse events during the study. Subcutaneous ghrelin administration enhances short-term food intake in dialysis patients with mild to moderate malnutrition.

Characterization of Photofrin Photobleaching for Singlet Oxygen Dose Estimation During Photodynamic Therapy of MLL Cells in Vitro

Physics in Medicine and Biology. Jun, 2005  |  Pubmed ID: 15901957

A singlet oxygen dose model is developed for PDT with Photofrin. The model is based on photosensitizer photobleaching kinetics, and incorporates both singlet oxygen and non-singlet oxygen mediated bleaching mechanisms. To test our model, in vitro experiments were performed in which MatLyLu (MLL) cells were incubated in Photofrin and then irradiated with 532 nm light. Photofrin fluorescence was monitored during treatment and, at selected fluence levels, cell viability was determined using a colony formation assay. Cell survival correlated well to calculated singlet oxygen dose, independent of initial Photofrin concentration or oxygenation. About 2 x 10(8) molecules of singlet oxygen per cell were required to reduce the surviving fraction by 1/e. Analysis of the photobleaching kinetics suggests that the lifetime of singlet oxygen in cells is 0.048 +/- 0.005 micros. The generation of fluorescent photoproducts was not a result of singlet oxygen reactions exclusively, and therefore did not yield additional information to aid in quantifying singlet oxygen dose.

Quantification of Fluorophore Concentration in Vivo Using Two Simple Fluorescence-based Measurement Techniques

Journal of Biomedical Optics. Mar-Apr, 2005  |  Pubmed ID: 15910081

The effect of photodynamic therapy treatments depends on the concentration of photosensitizer at the treatment site; thus a simple method to quantify concentration is desirable. This study compares the concentration of a fluorophore and sensitizer, aluminum phthalocyanine tetrasulfonate (AlPcS4), measured by two simple fluorescence-based techniques in vivo to post mortem chemical extraction and fluorometric assay of those tissues: skin, muscle, fascia, liver, and kidney (cortex and medulla). Fluorescence was excited and detected by a single optical fiber, or by an instrument that measured the ratio of the fluorescence and excitation reflectance. The in vivo measurements were compared to calibration measurements made in tissue-simulating phantoms to estimate the tissue concentrations. Reasonable agreement was observed between the concentration estimates of the two instruments in the lighter colored tissues (skin, muscle, and fascia). The in vivo measurements also agreed with the chemical extractions at low (< 0.6 microg/g) tissue concentrations, but underestimated higher tissue concentrations. Measurements of fluorescence lifetime in vivo demonstrated that AlPcS4 retains its mono-exponential decay in skin, muscle, and fascia tissues with a lifetime similar to that measured in aqueous tissue-simulating phantoms. In liver and kidney an additional short lifetime component was evident.

Is There a Role for Ghrelin and Peptide-YY in the Pathogenesis of Obesity in Adults with Acquired Structural Hypothalamic Damage?

The Journal of Clinical Endocrinology and Metabolism. Sep, 2005  |  Pubmed ID: 15972581

Obesity is a common sequel to hypothalamic tumors and their treatment, but the underlying mechanisms are not fully established.

Fat Digestion is Required for Suppression of Ghrelin and Stimulation of Peptide YY and Pancreatic Polypeptide Secretion by Intraduodenal Lipid

American Journal of Physiology. Endocrinology and Metabolism. Dec, 2005  |  Pubmed ID: 15998659

Stimulation of cholecystokinin and glucagon-like peptide-1 secretion by fat is mediated by the products of fat digestion. Ghrelin, peptide YY (PYY), and pancreatic polypeptide (PP) appear to play an important role in appetite regulation, and their release is modulated by food ingestion, including fat. It is unknown whether fat digestion is a prerequisite for their suppression (ghrelin) or release (PYY, PP). Moreover, it is not known whether small intestinal exposure to fat is sufficient to suppress ghrelin secretion. Our study aimed to resolve these issues. Sixteen healthy young males received, on two separate occasions, 120-min intraduodenal infusions of a long-chain triglyceride emulsion (2.8 kcal/min) 1) without (condition FAT) or 2) with (FAT-THL) 120 mg of tetrahydrolipstatin (THL, lipase inhibitor), followed by a standard buffet-style meal. Blood samples for ghrelin, PYY, and PP were taken throughout. FAT infusion was associated with a marked, and progressive, suppression of plasma ghrelin from t = 60 min (P < 0.001) and stimulation of PYY from t = 30 min (P < 0.01). FAT infusion also stimulated plasma PP (P < or = 0.01), and the release was immediate. FAT-THL completely abolished the FAT-induced changes in ghrelin, PYY, and PP. In response to the meal, plasma ghrelin was further suppressed, and PYY and PP stimulated, during both FAT and FAT-THL infusions. In conclusion, in healthy humans, 1) the presence of fat in the small intestine suppresses ghrelin secretion, and 2) fat-induced suppression of ghrelin and stimulation of PYY and PP is dependent on fat digestion.

Subcutaneous Oxyntomodulin Reduces Body Weight in Overweight and Obese Subjects: a Double-blind, Randomized, Controlled Trial

Diabetes. Aug, 2005  |  Pubmed ID: 16046306

This study investigated the effect of subcutaneously administered oxyntomodulin on body weight in healthy overweight and obese volunteers. Participants self-administered saline or oxyntomodulin subcutaneously in a randomized, double-blind, parallel-group protocol. Injections were self-administered for 4 weeks, three times daily, 30 min before each meal. The volunteers were asked to maintain their regular diet and level of physical exercise during the study period. Subjects' body weight, energy intake, and levels of adipose hormones were assessed at the start and end of the study. Body weight was reduced by 2.3 +/- 0.4 kg in the treatment group over the study period compared with 0.5 +/- 0.5 kg in the control group (P = 0.0106). On average, the treatment group had an additional 0.45-kg weight loss per week. The treatment group demonstrated a reduction in leptin and an increase in adiponectin. Energy intake by the treatment group was significantly reduced by 170 +/- 37 kcal (25 +/- 5%) at the initial study meal (P = 0.0007) and by 250 +/- 63 kcal (35 +/- 9%) at the final study meal (P = 0.0023), with no change in subjective food palatability. Oxyntomodulin treatment resulted in weight loss and a change in the levels of adipose hormones consistent with a loss of adipose tissue. The anorectic effect was maintained over the 4-week period. Oxyntomodulin represents a potential therapy for obesity.

Kisspeptin-54 Stimulates the Hypothalamic-pituitary Gonadal Axis in Human Males

The Journal of Clinical Endocrinology and Metabolism. Dec, 2005  |  Pubmed ID: 16174713

Mutation of the G protein-coupled receptor 54 is associated with a failure of reproductive function. The endogenous neuropeptide agonist for G protein-coupled receptor 54, kisspeptin, potently stimulates the hypothalamic-pituitary-gonadal axis in rodents and primates.

The Coming Influenza Pandemic: Lessons from the Past for the Future

The Journal of the American Osteopathic Association. Nov, 2005  |  Pubmed ID: 16368913

Documenting Junctional Ectopic Tachycardia Following Pediatric Open Heart Surgery

Journal of the Medical Association of Thailand = Chotmaihet Thangphaet. Nov, 2005  |  Pubmed ID: 16858961

To determine appropriated documentations for diagnosis junctional ectopic tachycardia (JET) before treatment in post-operative open heart surgery and identify risk factors for post-operative cardiac arrhythmias in children.

Photobleaching Kinetics, Photoproduct Formation, and Dose Estimation During ALA Induced PpIX PDT of MLL Cells Under Well Oxygenated and Hypoxic Conditions

Photochemical & Photobiological Sciences : Official Journal of the European Photochemistry Association and the European Society for Photobiology. Jan, 2006  |  Pubmed ID: 16395430

Fluorescence photobleaching and photoproduct formation were investigated during delta-aminolevulinic acid (ALA) induced protoporphyrin IX (PpIX) PDT of MLL cells in vitro. Cells were incubated in either 0.1 or 1.0 mM ALA for 4 h and were treated with 532 nm or 635 nm light under well oxygenated or hypoxic conditions. Fluorescence spectra were acquired during treatment. Photobleaching and photoproduct formation were quantified using singular value decomposition fitting of fluorescence spectra to experimentally determined basis spectra for PpIX, photoprotoporphyrin (Ppp), product II (peak at 655 nm), and product III (peak at 618 nm). PpIX photobleaching occurred under both normal and hypoxic conditions. The photobleaching kinetics could not be explained by purely first- or second-order photobleaching kinetics, and were attributed to differences in PpIX binding at the two ALA incubation concentrations. Ppp was the main photoproduct and accumulated in higher levels in the absence of oxygen, likely a result of reduced Ppp photobleaching under hypoxia. Increases in product II fluorescence occurred mainly in the presence of oxygen. To assess potential fluorescence based PDT dose metrics, cell viability was measured at select times during treatment using a colony formation assay. Cell survival correlated well to changes in product II fluorescence, independent of oxygenation, sensitizer concentration, and treatment wavelength, suggesting that this product is primarily a result of singlet oxygen mediated reactions and may potentially be useful to quantify singlet oxygen dose during PDT.

Changes in Appetite Related Gut Hormones in Intensive Care Unit Patients: a Pilot Cohort Study

Critical Care (London, England). Feb, 2006  |  Pubmed ID: 16420657

The nutritional status of patients in the intensive care unit (ICU) appears to decline not only during their stay in the ICU but also after discharge from the ICU. Recent evidence suggests that gut released peptides, such as ghrelin and peptide YY (PYY) regulate the initiation and termination of meals and could play a role in the altered eating behaviour of sick patients. The aim of this study was to assess the patterns of ghrelin and PYY levels during the stay of ICU patients in hospital.

Spectrally Resolved Bioluminescence Optical Tomography

Optics Letters. Feb, 2006  |  Pubmed ID: 16480210

Spectrally resolved bioluminescence optical tomography is an approach to recover images of luciferase activity within a volume using multiwavelength emission data from internal bioluminescence sources. The underlying problem of uniqueness associated with nonspectrally resolved intensity-based bioluminescence tomography is highlighted. Reconstructed images of bioluminescence are presented by using as input both simulated and real multiwavelength data from a tissue-simulating phantom. The location of the internal bioluminescence is obtained with 1 mm accuracy. Further, the amplitude of the reconstructed source is proportional to the actual bioluminescence intensity.

The Language of Fighting Invasive Species

Science (New York, N.Y.). Feb, 2006  |  Pubmed ID: 16491517

Effect of Fatty Acid Chain Length on Suppression of Ghrelin and Stimulation of PYY, GLP-2 and PP Secretion in Healthy Men

Peptides. Jul, 2006  |  Pubmed ID: 16563563

We have evaluated the effects of fatty acid chain length on ghrelin, peptide YY (PYY), glucagon-like peptide-2 (GLP-2) and pancreatic polypeptide (PP) secretion and hypothesized that intraduodenal administration of dodecanoic ("C12"), but not decanoic ("C10"), acid would decrease plasma ghrelin and increase PYY, GLP-2 and PP concentrations. Plasma hormone concentrations were measured in seven healthy men during 90-min intraduodenal infusions of: (i) C12, (ii) C10 or (iii) control (rate: 2 ml/min, 0.375 kcal/min for C12/C10) and after a buffet-meal consumed following the infusion. C12 markedly suppressed plasma ghrelin and increased both PYY and GLP-2 (all P < 0.05) compared with control and C10, while C10 had no effect. Both C10 and C12 increased PP concentrations slightly (P < 0.05). We conclude that the effects of intraduodenal fatty acids on ghrelin, PYY and GLP-2 secretion are dependent on their chain length.

Neuropeptide S Stimulates the Hypothalamo-pituitary-adrenal Axis and Inhibits Food Intake

Endocrinology. Jul, 2006  |  Pubmed ID: 16574794

Neuropeptide S (NPS) is a recently discovered peptide shown to be involved in the modulation of arousal and fear responses. It has also been shown that lateral ventricle administration of NPS causes a significant decrease in food intake. Neuropeptides involved in the modulation of arousal have been shown to be involved in the regulation of the hypothalamo-pituitary adrenal (HPA) axis and food intake. In this study, we have examined the effect of intracerebroventricular (ICV) administration of NPS on behavior, regulation of the HPA axis, and food intake. ICV NPS significantly increased plasma ACTH and corticosterone 10 and 40 min after injection, respectively. A single ICV injection of NPS caused a significant increase in rearing activity as well as ambulatory movement for up to 45 min after injection. We then studied the effect of paraventricular nucleus (PVN) administration of NPS on the regulation of the HPA axis, behavior, and food intake. There was a significant increase in plasma ACTH and corticosterone after a single NPS PVN injection. Incubation of hypothalamic explants with increasing concentrations of NPS caused a significant increase in CRH and arginine vasopressin release. In addition, PVN administration of NPS dose-dependently inhibited food intake in the first hour after injection, although no effect on food intake was seen after this time. PVN administration of NPS caused a significant increase in rearing activity. These data demonstrate a novel role for NPS in the stimulation of the HPA axis.

Faith Without Works

The Journal of the American Osteopathic Association. Mar, 2006  |  Pubmed ID: 16585379

Telemedicine Program Delivers Healthcare Services Far and Wide

Biomedical Instrumentation & Technology / Association for the Advancement of Medical Instrumentation. 2006  |  Pubmed ID: 16596844

Plasma Kisspeptin is Raised in Patients with Gestational Trophoblastic Neoplasia and Falls During Treatment

American Journal of Physiology. Endocrinology and Metabolism. Nov, 2006  |  Pubmed ID: 16757546

Kisspeptin is a 54-amino acid peptide, encoded by the anti-metastasis gene KiSS-1, that activates G protein-coupled receptor 54 (GPR54). The kisspeptin-GPR54 system is critical to normal reproductive development. KiSS-1 gene expression is increased in the human placenta in normal and molar pregnancies. Circulating kisspeptin is dramatically increased in normal pregnancy, but levels in GTN have not previously been reported. The present study was designed to determine whether plasma kisspeptin levels are altered in patients with malignant GTN. Thirty-nine blood samples were taken from 11 patients with malignant GTN at presentation during and after chemotherapy. Blood was also sampled from nonpregnant and pregnant volunteers. Plasma kisspeptin IR and hCG concentrations were measured. Plasma kisspeptin IR concentration in nonpregnant (n = 16) females was <2 pmol/l. Plasma kisspeptin IR in females was 803 +/- 125 pmol/l in the first trimester of pregnancy (n = 13), 2,483 +/- 302 pmol/l in the third trimester of pregnancy (n = 7), and <2 pmol/l on day 15 postpartum (n = 7). Plasma kisspeptin IR and hCG concentrations in patients with malignant GTN were elevated at presentation and fell during and after treatment with chemotherapy in each patient (mean plasma kisspeptin IR: prechemotherapy 1,363 +/- 1,076 pmol/l vs. post-chemotherapy <2 pmol/l, P < 0.0001; mean plasma hCG: prechemotherapy 227,191 +/- 152,354 U/l vs. postchemotherapy 2 U/l, P < 0.0001). Plasma kisspeptin IR strongly positively correlated with plasma hCG levels (r(2) = 0.99, P < 0.0001). Our results suggest that measurement of plasma kisspeptin IR may be a novel tumor marker in patients with malignant GTN.

Application of the Modified Spherical Harmonics Method to Some Problems in Biomedical Optics

Physics in Medicine and Biology. Jun, 2006  |  Pubmed ID: 16757857

It is demonstrated that a semi-analytical method, modified spherical harmonics (MSH), is a fast and rigorous solution for the radiative transport equation in an infinite medium containing an isotropic source. The optical properties of the medium can be determined using an inverse scheme based on fluence data (including phase if a modulated source is used) without the drawbacks inherent in the diffusion approximation. The MSH method can also be used to solve for the fluorescence fluence due to a point excitation source in an infinite medium.

Chronic Subcutaneous Administration of Kisspeptin-54 Causes Testicular Degeneration in Adult Male Rats

American Journal of Physiology. Endocrinology and Metabolism. Nov, 2006  |  Pubmed ID: 16787965

The kisspeptins are KiSS-1 gene-derived peptides that signal through the G protein-coupled receptor-54 (GPR54) and have recently been shown to be critical regulators of reproduction. Acute intracerebroventricular or peripheral administration of kisspeptin stimulates the hypothalamic-pituitary-gonadal (HPG) axis. This effect is thought to be mediated via the hypothalamic gonadotropin-releasing hormone (GnRH) system. Chronic administration of GnRH agonists paradoxically suppresses the HPG axis after an initial agonistic stimulation. We investigated the effects of continuous peripheral kisspeptin administration in male rats by use of Alzet minipumps. Initially we compared the effects of acute subcutaneous administration of kisspeptin-10, -14, and -54 on the HPG axis. Kisspeptin-54 produced the greatest increase in plasma LH and total testosterone at 60 min postinjection and was used in the subsequent continuous administration experiments. Chronic subcutaneous long-term administration of 50 nmol kisspeptin-54/day for 13 days decreased testicular weight. Histological examination showed degeneration of the seminiferous tubules associated with a significant decrease in the circulating levels of the testes-derived hormone, inhibin B. Plasma free and total testosterone were also lower, although these changes did not reach statistical significance. Further studies examined the effects of shorter periods of continuous kisspeptin administration. Subcutaneous administration of 50 nmol kisspeptin-54 for 1 day increased plasma LH and testosterone. This effect was lost after 2 days of administration, suggesting a downregulation of the HPG axis response to kisspeptin following continuous administration. These findings indicate that kisspeptin may provide a novel tool for the manipulation of the HPG axis and spermatogenesis.

Singlet Oxygen Luminescence Dosimetry (SOLD) for Photodynamic Therapy: Current Status, Challenges and Future Prospects

Photochemistry and Photobiology. Sep-Oct, 2006  |  Pubmed ID: 16808593

As photodynamic therapy (PDT) continues to develop and find new clinical indications, robust individualized dosimetry is warranted to achieve effective treatments. We posit that the most direct PDT dosimetry is achieved by monitoring singlet oxygen (1O2), the major cytotoxic species generated photochemically during PDT. Its detection and quantification during PDT have been long-term goals for PDT dosimetry and the development of techniques for this, based on detection of its near-infrared luminescence emission (1270 nm), is at a noteworthy stage of development. We begin by discussing the theory behind singlet-oxygen luminescence dosimetry (SOLD) and the seminal contributions that have brought SOLD to its current status. Subsequently, technology developments that could potentially improve SOLD are discussed, together with future areas of research, as well as the potential limitations of this method. We conclude by examining the major thrusts for future SOLD applications: as a tool for quantitative photobiological studies, a point of reference to evaluate other PDT dosimetry techniques, the optimal means to evaluate new photosensitizers and delivery methods and, potentially, a direct and robust clinical dosimetry system.

Failed Back Surgery Syndrome: Diagnostic Evaluation

The Journal of the American Academy of Orthopaedic Surgeons. Sep, 2006  |  Pubmed ID: 16959891

Failed back surgery syndrome is a common problem with enormous costs to patients, insurers, and society. The etiology of failed back surgery can be poor patient selection, incorrect diagnosis, suboptimal selection of surgery, poor technique, failure to achieve surgical goals, and/or recurrent pathology. Successful intervention in this difficult patient population requires a detailed history, precise physical examination, and carefully chosen diagnostic tests. The diagnostic evaluation should endeavor to accurately identify symptoms, rule out extraspinal causes, identify a specific spinal etiology, and assess the psychological state of the patient. Only after these factors have been assessed can further treatment be planned.

Review of Tissue Simulating Phantoms for Optical Spectroscopy, Imaging and Dosimetry

Journal of Biomedical Optics. Jul-Aug, 2006  |  Pubmed ID: 16965130

Optical spectroscopy, imaging, and therapy tissue phantoms must have the scattering and absorption properties that are characteristic of human tissues, and over the past few decades, many useful models have been created. In this work, an overview of their composition and properties is outlined, by separating matrix, scattering, and absorbing materials, and discussing the benefits and weaknesses in each category. Matrix materials typically are water, gelatin, agar, polyester or epoxy and polyurethane resin, room-temperature vulcanizing (RTV) silicone, or polyvinyl alcohol gels. The water and hydrogel materials provide a soft medium that is biologically and biochemically compatible with addition of organic molecules, and are optimal for scientific laboratory studies. Polyester, polyurethane, and silicone phantoms are essentially permanent matrix compositions that are suitable for routine calibration and testing of established systems. The most common three choices for scatters have been: (1.) lipid based emulsions, (2.) titanium or aluminum oxide powders, and (3.) polymer microspheres. The choice of absorbers varies widely from hemoglobin and cells for biological simulation, to molecular dyes and ink as less biological but more stable absorbers. This review is an attempt to indicate which sets of phantoms are optimal for specific applications, and provide links to studies that characterize main phantom material properties and recipes.

Investigation of Light Propagation Models to Determine the Optical Properties of Tissue from Interstitial Frequency Domain Fluence Measurements

Journal of Biomedical Optics. Jul-Aug, 2006  |  Pubmed ID: 16965132

Four models, standard diffusion approximation (SDA), single Monte Carlo (SMC), delta-P1, and isotropic similarity (ISM), are developed and evaluated as forward calculation tools in the estimation of tissue optical properties. The inverse calculation uses the ratio of the fluences and phase difference at two locations close to an intensity modulated isotropic source to recover the reduced scattering coefficient mus' and the absorption coefficient mua. Diffusion theory allows recovery of optical properties (OPs) within 5% for media with mus'mua>10. The performance of the delta-P1 model is similar to SDA, with limited enhanced accuracy. The collimation approximation may limit the use of the delta-P1 model for spherical geometry, and/or the fluence may not be accurately calculated by this model. The SMC model is the best, recovering OPs within 10% regardless of the albedo. However, the necessary restriction of the searched OPs space is inconvenient. The performance of ISM is similar to that of diffusion theory for media with mus'mua>10, and better for 15.

A Molecular Neuroethological Approach for Identifying and Characterizing a Cascade of Behaviorally Regulated Genes

Proceedings of the National Academy of Sciences of the United States of America. Oct, 2006  |  Pubmed ID: 17018643

Songbirds have one of the most accessible neural systems for the study of brain mechanisms of behavior. However, neuroethological studies in songbirds have been limited by the lack of high-throughput molecular resources and gene-manipulation tools. To overcome these limitations, we constructed 21 regular, normalized, and subtracted full-length cDNA libraries from brains of zebra finches in 57 developmental and behavioral conditions in an attempt to clone as much of the brain transcriptome as possible. From these libraries, approximately 14,000 transcripts were isolated, representing an estimated 4,738 genes. With the cDNAs, we created a hierarchically organized transcriptome database and a large-scale songbird brain cDNA microarray. We used the arrays to reveal a set of 33 genes that are regulated in forebrain vocal nuclei by singing behavior. These genes clustered into four anatomical and six temporal expression patterns. Their functions spanned a large range of cellular and molecular categories, from signal transduction, trafficking, and structural, to synaptically released molecules. With the full-length cDNAs and a lentiviral vector system, we were able to overexpress, in vocal nuclei, proteins of representative singing-regulated genes in the absence of singing. This publicly accessible resource can now be used to study molecular neuroethological mechanisms of behavior.

Peptide YY (PYY) is Increased in Elderly Patients with Femoral Neck Fractures: a Prospective Cohort Study

JPEN. Journal of Parenteral and Enteral Nutrition. Nov-Dec, 2006  |  Pubmed ID: 17047180

Peptide YY (PYY), a gut peptide, has recently been shown to inhibit appetite. The role of this peptide in elderly nutritionally-compromised patients with femoral neck fracture (FNF) has not been investigated. In this study, we investigated the longitudinal pattern of PYY levels during hospital stay and investigated the postprandial PYY response to a standard meal in patients with FNF and matched controls.

Evidence for Multiple Manipulation Processes in Prefrontal Cortex

Brain Research. Dec, 2006  |  Pubmed ID: 17070786

The prefrontal cortex (PFC) is known to subserve working memory (WM) processes. Brain imaging studies of WM using delayed response tasks (DRTs) have shown memory-load-dependent activation increases in dorsal prefrontal cortex (PFC) regions. These activation increases are believed to reflect manipulation of to-be-remembered information in the service of memory-consolidation. This speculation has been based on observations of similar activation increases in tasks that overtly require manipulation by instructing participants to reorder to-be-remembered list items. In this study, we tested the assumption of functional equivalence between these two types of WM tasks. Participants performed a DRT under two conditions with memory loads ranging from 3 to 6 letters. In an "item-order" condition, participants were required to remember letters in the order in which they were presented. In a "reordering" condition, participants were required to remember the letters in alphabetical order. Load-related activation increases were observed during the encoding and maintenance periods of the order maintenance condition, whereas load-related activation decreases were observed in the same periods of the reordering condition. These results suggest that (1) the neural substrates associated with long-list retention and those associated with reordering are not equivalent, (2) cognitive processes associated with long-list retention may be more closely approximated by item-order maintenance than by reordering, and (3) multiple forms of WM manipulation are dissociable on the basis of fMRI data.

Mechanisms of Change: Animal Models in Osteopathic Medical Research

The Journal of the American Osteopathic Association. Oct, 2006  |  Pubmed ID: 17122028

Valerian for Sleep: a Systematic Review and Meta-analysis

The American Journal of Medicine. Dec, 2006  |  Pubmed ID: 17145239

Insomnia affects approximately one-third of the adult population and contributes to increased rates of absenteeism, health care use, and social disability. Extracts of the roots of valerian (Valeriana officinalis) are widely used for inducing sleep and improving sleep quality. A systematic review of randomized, placebo-controlled trials of valerian for improving sleep quality is presented. An extensive literature search identified 16 eligible studies examining a total of 1093 patients. Most studies had significant methodologic problems, and the valerian doses, preparations, and length of treatment varied considerably. A dichotomous outcome of sleep quality (improved or not) was reported by 6 studies and showed a statistically significant benefit (relative risk of improved sleep = 1.8, 95% confidence interval, 1.2-2.9), but there was evidence of publication bias in this summary measure. The available evidence suggests that valerian might improve sleep quality without producing side effects. Future studies should assess a range of doses of standardized preparations of valerian and include standard measures of sleep quality and safety.

Determination of the Optical Properties of Tissue-simulating Phantoms from Interstitial Frequency Domain Measurements of Relative Fluence and Phase Difference

Optics Express. Jul, 2006  |  Pubmed ID: 19516827

We estimated the absorption and reduced scattering coefficients of tissue-simulating phantoms from interstitial measurements of the phase difference and relative amplitude signals at two distances from a sinusoidally modulated isotropic source. It was found that absorption and reduced scattering coefficients can be recovered within 10% and slightly over 10% respectively, using either the data collected by two detectors 3mm apart or by two detectors 5mm apart with light collected by one detector attenuated by a neutral density filter. This accuracy was achieved over a wide range of optical properties, mu(a)=0.008 to 0.17mm(-1) and mu(s)'=0.3 to 1.8mm(-1). Additional factors affecting accuracy including source anisotropy, uncertainty in fiber placement, phase amplitude crosstalk, and the forward light propagation model (the combined isotropic similarity model and standard diffusion approximation versus the modified spherical harmonics method) were studied by Monte Carlo simulations (first two factors) and experiments (last two factors).

Depolarization-induced Calcium Responses in Sympathetic Neurons: Relative Contributions from Ca2+ Entry, Extrusion, ER/mitochondrial Ca2+ Uptake and Release, and Ca2+ Buffering

The Journal of General Physiology. Jan, 2007  |  Pubmed ID: 17190902

Many models have been developed to account for stimulus-evoked [Ca(2+)] responses, but few address how responses elicited in specific cell types are defined by the Ca(2+) transport and buffering systems that operate in the same cells. In this study, we extend previous modeling studies by linking the time course of stimulus-evoked [Ca(2+)] responses to the underlying Ca(2+) transport and buffering systems. Depolarization-evoked [Ca(2+)](i) responses were studied in sympathetic neurons under voltage clamp, asking how response kinetics are defined by the Ca(2+) handling systems expressed in these cells. We investigated five cases of increasing complexity, comparing observed and calculated responses deduced from measured Ca(2+) handling properties. In Case 1, [Ca(2+)](i) responses were elicited by small Ca(2+) currents while Ca(2+) transport by internal stores was inhibited, leaving plasma membrane Ca(2+) extrusion intact. In Case 2, responses to the same stimuli were measured while mitochondrial Ca(2+) uptake was active. In Case 3, responses were elicited as in Case 2 but with larger Ca(2+) currents that produce larger and faster [Ca(2+)](i) elevations. Case 4 included the mitochondrial Na/Ca exchanger. Finally, Case 5 included ER Ca(2+) uptake and release pathways. We found that [Ca(2+)](i) responses elicited by weak stimuli (Cases 1 and 2) could be quantitatively reconstructed using a spatially uniform model incorporating the measured properties of Ca(2+) entry, removal, and buffering. Responses to strong depolarization (Case 3) could not be described by this model, but were consistent with a diffusion model incorporating the same Ca(2+) transport and buffering descriptions, as long as endogenous buffers have low mobility, leading to steep radial [Ca(2+)](i) gradients and spatially nonuniform Ca(2+) loading by mitochondria. When extended to include mitochondrial Ca(2+) release (Case 4) and ER Ca(2+) transport (Case 5), the diffusion model could also account for previous measurements of stimulus-evoked changes in total mitochondrial and ER Ca concentration.

Role of Central Nervous System and Ovarian Insulin Receptor Substrate 2 Signaling in Female Reproductive Function in the Mouse

Biology of Reproduction. Jun, 2007  |  Pubmed ID: 17329594

Insulin receptor signaling regulates female reproductive function acting in the central nervous system and ovary. Female mice that globally lack insulin receptor substrate (IRS) 2, which is a key mediator of insulin receptor action, are infertile with defects in hypothalamic and ovarian functions. To unravel the tissue-specific roles of IRS2, we examined reproductive function in female mice that lack Irs2 only in the neurons. Surprisingly, these animals had minimal defects in pituitary and ovarian hormone levels, ovarian anatomy and function, and breeding performance, which indicates that the central nervous system IRS2 is not an obligatory signaling component for the regulation of reproductive function. Therefore, we undertook a detailed analysis of ovarian function in a novel Irs2 global null mouse line. Comparative morphometric analysis showed reduced follicle size, increased numbers of atretic follicles, as well as impaired oocyte growth and antral cavity development in Irs2 null ovaries. Granulosa cell proliferation was also defective in the Irs2 null ovaries. Furthermore, the insulin- and eCG-stimulated phosphoinositide-3-OH kinase signaling events, which included phosphorylation of Akt/protein kinase B and glycogen synthase kinase 3-beta, were impaired, whereas mitogen-activated protein kinase signaling was preserved in Irs2 null ovaries. These abnormalities were associated with reduced expression of cyclin D2 and increased CDKN1B levels, which indicates dysregulation of key components of the cell cycle apparatus implicated in ovarian function. Our data suggest that ovarian rather than central nervous system IRS2 signaling is important in the regulation of female reproductive function.

Kisspeptin-54 Stimulates Gonadotropin Release Most Potently During the Preovulatory Phase of the Menstrual Cycle in Women

The Journal of Clinical Endocrinology and Metabolism. Oct, 2007  |  Pubmed ID: 17635940

Kisspeptin, the endogenous ligand of the G protein-coupled receptor 54, is a key regulator of the hypothalamo-pituitary-gonadal (HPG) axis. GPR54-null mice exhibit reproductive dysfunction, and exogenous kisspeptin potently stimulates the HPG axis in rodents, primates, and human males. The effects of kisspeptin administration to human females are unknown.

Visual Working Memory for Global, Object, and Part-based Information

Memory & Cognition. Jun, 2007  |  Pubmed ID: 17848031

We investigated visual working memory for novel objects and parts of novel objects. After a delay period, participants showed strikingly more accurate performance recognizing a single whole object than the parts of that object. This bias to remember whole objects, rather than parts, persisted even when the division between parts was clearly defined and the parts were disconnected from each other so that, in order to remember the single whole object, the participants needed to mentally combine the parts. In addition, the bias was confirmed when the parts were divided by color. These experiments indicated that holistic perceptual-grouping biases are automatically used to organize storage in visual working memory. In addition, our results suggested that the bias was impervious to top-down consciously directed control, because when task demands were manipulated through instruction and catch trials, the participants still recognized whole objects more quickly and more accurately than their parts. This bias persisted even when the whole objects were novel and the parts were familiar. We propose that visual working memory representations depend primarily on the global configural properties of whole objects, rather than part-based representations, even when the parts themselves can be clearly perceived as individual objects. This global configural bias beneficially reduces memory load on a capacity-limited system operating in a complex visual environment, because fewer distinct items must be remembered.

Postprandial Ghrelin Suppression is Exaggerated Following Major Surgery; Implications for Nutritional Recovery

Nutrition & Metabolism. 2007  |  Pubmed ID: 17922905

Meeting patients' nutritional requirements and preventing malnutrition is a challenge following major surgical procedures. The role of ghrelin in nutritional recovery after non-gastrointestinal major surgery is unknown. We used coronary artery bypass grafting (CABG) as an example of anticipated good recovery post major surgery.Seventeen patients undergoing CABG (mean +/- SEM: 70.1 +/- 2.2 yrs, BMI 29.1 +/- 1.4 kg/m2, 15 male) underwent fasting and postprandial (45 mins after standard test breakfast) blood sampling pre-operatively (day 0), post-operatively (day 6) and at follow-up (day 40). Changes in food intake, biochemical and anthropometric markers of nutritional status were recorded. A comparison was made to 17 matched healthy controls (70.6 +/- 2.3 yrs, BMI 28.4 +/- 1.3 kg/m2).We observed significantly increased post-operative and follow-up fasting ghrelin concentrations compared with pre-operatively (pre-op. 402 +/- 42 pmol/L vs post-op. 642 +/- 97 pmol/L vs follow-up 603 +/- 94 pmol/L) (ANOVA p < 0.05). Significantly exaggerated postprandial suppression of ghrelin was seen postoperatively and continued until follow-up (Delta pre-op. 10 +/- 51 pmol/L vs Delta post-op. -152 +/- 43 pmol/L vs Delta follow-up -159 +/- 65 pmol/L, p < 0.05). This was associated with a 50% reduction in food intake {post-op. 4.5 +/- 0.5 MJ/D (1076 +/- 120 kcal/D) compared with estimated requirements 9.9 +/- 0.5 MJ/D (2366 +/- 120 kcal/D)}, leading to a 4% weight loss and a 5% reduction in muscle arm circumference loss over length of follow up.Our data support the hypothesis that prolonged changes in fasting and postprandial plasma ghrelin concentrations are associated with impaired nutritional recovery after CABG. These findings reinforce the need to investigate ghrelin in other patients groups undergoing major surgery.

Cochlear Implantation in Organ Transplantation

The Laryngoscope. Jan, 2008  |  Pubmed ID: 18251033

Compared to immunocompetent patients, organ transplant recipients receiving immunosuppressant medications may experience higher rates of postoperative complications. This study was designed to retrospectively review the outcomes of cochlear implantation among organ transplant patients.

Preanalytical Factors Affecting RIA Measurement of Plasma Kisspeptin

Clinical Chemistry. Mar, 2008  |  Pubmed ID: 18310154

The Physics, Biophysics and Technology of Photodynamic Therapy

Physics in Medicine and Biology. May, 2008  |  Pubmed ID: 18401068

Photodynamic therapy (PDT) uses light-activated drugs to treat diseases ranging from cancer to age-related macular degeneration and antibiotic-resistant infections. This paper reviews the current status of PDT with an emphasis on the contributions of physics, biophysics and technology, and the challenges remaining in the optimization and adoption of this treatment modality. A theme of the review is the complexity of PDT dosimetry due to the dynamic nature of the three essential components -- light, photosensitizer and oxygen. Considerable progress has been made in understanding the problem and in developing instruments to measure all three, so that optimization of individual PDT treatments is becoming a feasible target. The final section of the review introduces some new frontiers of research including low dose rate (metronomic) PDT, two-photon PDT, activatable PDT molecular beacons and nanoparticle-based PDT.

A Novel Clinical-trial Design for the Study of Massage Therapy

Complementary Therapies in Medicine. Jun, 2008  |  Pubmed ID: 18534330

To develop and test the feasibility and acceptability of a structured design for a massage therapy clinical trial that included a treatment arm designed to control for the non-specific effects of a massage therapy intervention.

Pyroglutamylated RFamide Peptide 43 Stimulates the Hypothalamic-pituitary-gonadal Axis Via Gonadotropin-releasing Hormone in Rats

Endocrinology. Sep, 2008  |  Pubmed ID: 18535111

Although it is established that other members of the RFamide family stimulate the hypothalamic-pituitary-gonadal axis, the influence of the novel pyroglutamylated RFamide peptide 43 (QRFP43) is not known. We show intracerebroventricular (icv) administration of QRFP43 (2 nmol) to male rats increased plasma LH and FSH levels at 40 min after injection. icv administration of 3 nmol QRFP43 did not affect food intake in ad-libitum-fed male rats. The icv administration of 2 nmol QRFP43 did not significantly influence behavior in male rats. Intraperitoneal administration of doses up to 1200 nmol/kg QRFP43 in male rats did not significantly influence circulating gonadotropin or sex steroid levels. In vitro, QRFP43 stimulated GnRH release from hypothalamic explants from male rats and from GT1-7 cells. Pretreatment with a GnRH receptor antagonist, cetrorelix, blocked the increase in plasma LH levels after icv administration of QRFP43 (2 nmol). These results suggest that icv QRFP43 activates the hypothalamic-pituitary-gonadal axis via GnRH.

The Effects of Acute Stress on Human Prefrontal Working Memory Systems

Physiology & Behavior. Oct, 2008  |  Pubmed ID: 18692209

We examined the relationship between acute stress and prefrontal-cortex (PFC) based working memory (WM) systems using behavioral (Experiment 1) and functional magnetic resonance imaging (fMRI; Experiment 2) paradigms. Subjects performed a delayed-response item-recognition task, with alternating blocks of high and low WM demand trials. During scanning, participants performed this task under three stress conditions: cold stress (induced by cold-water hand-immersion), a room temperature water control (induced by tepid-water hand-immersion), and no-water control (no hand-immersion). Performance was affected by WM demand, but not stress. Cold stress elicited greater salivary cortisol readings in behavioral subjects, and greater PFC signal change in fMRI subjects, than control conditions. These results suggest that, under stress, increases in PFC activity may be necessary to mediate cognitive processes that maintain behavioral organization.

Quantitative Fluorescence Imaging of Point-like Sources in Small Animals

Physics in Medicine and Biology. Oct, 2008  |  Pubmed ID: 18827315

A planar imaging approach is described for the in vivo quantitative reconstruction of fluorescent point sources in small animals. The method uses the diffusion approximation as a forward model of light propagation from a point source in a homogeneous tissue to find source depth and strength. The tissue optical properties obtained from video reflectometry measurements were used to compensate for the effects of tissue heterogeneity. The method was evaluated on images of fluorescent sources implanted 2-8.5 mm deep in the thigh and abdomen of rats post mortem. In more than 70% of the total number of implants the source depth was retrieved with an error of less than 1 mm. The largest absolute error was 1.9 mm. In retrieving source strength, the errors ranged from 0.4% to 89% generally increasing with increased source depth.

Effect of Liposomal Confinement on Photochemical Properties of Photosensitizers with Varying Hydrophilicity

Journal of Biomedical Optics. Jul-Aug, 2008  |  Pubmed ID: 19021321

Preferential tumor localization and the aggregation state of photosensitizers (PSs) can depend on the hydrophilic/hydrophobic nature of the molecule and affect their phototoxicity. In this study, three PSs of different hydrophilicity are introduced in liposomes to understand the structure-photochemistry relationship of PSs in this cellular model system. Absorbance and fluorescence spectra of amphiphilic aluminum (III) phthalocyanine disulfonate chloride adjacent isomer (Al-2), hydrophilic aluminum (III) phthalocyanine chloride tetrasulfonic acid (Al-4), and lipophilic 2-(1-hexyloxyethyl)-2-devinyl pyropheophorbide (HPPH) are compared in a liposomal confined state with free PS in bulk solution. For fluorescence measurements, a broad range of concentrations of both bulk and liposomal confined PSs are examined to track the transition from monomers to dimers or higher order aggregates. Epifluorescence microscopy, absorbance, and fluorescence measurements all confirm different localization of the PSs in liposomes, depending on their hydrophilicity. In turn, the localization affects the aggregation of molecules inside the liposome cell model. Data obtained with such cellular models could be useful in optimizing the photochemical properties of photosensitizing drugs based on their structure-dependent interactions with cellular media and subcellular organelles.

Effect of Liposomal Confinement on Photothermal and Photo-oximetric Fluorescence Lifetimes of Photosensitizers with Varying Hydrophilicity

Journal of Biomedical Optics. Jul-Aug, 2008  |  Pubmed ID: 19021322

The time-resolved fluorescence of photosensitizers (PSs) of varying hydrophobicities, di-and tetrasulfonated Al phthalocyanines (Al-2 and Al-4), and Photochlor (HPPH), was investigated in liposomes used as cell-mimetic models. Using frequency-and time-domain apparatus, the fluorescence lifetime, tau(fluo), was compared for PSs free in aqueous solution and in a liposome-associated state at varied temperatures (25 to 78 degrees C) and oxygen concentrations (0-190 microM). The analysis of tau(fluo) revealed different decay behaviors for the free-solution and liposome-confined PSs, most significantly for the lipophilic HPPH. Hydrophilic PS drugs (Al-4, Al-2) were less affected by the liposomal confinement, depending on the relative hydrophilicity of the compound and the consequent localization in liposomes. Changes in the emission decay due to confinement were detected as differences in the lifetime between the bulk solution and the liposome-localized PS in response to heating and deoxygenation. Specifically, hydrophilic Al-4 produced an identical lifetime trend as a function of temperature both in solu and in a liposome-confined state. Hydrophobic HPPH exhibited a fundamental transformation in its fluorescence decay kinetics, transitioning from a multiexponential (in free solution) to single-exponential (in liposome) decay. Deoxygenation resulted in a ubiquitous tau(fluo) increase for all PSs in free solution, while the opposite, a tau(fluo) decrease, occurred in all liposomal PSs.

In Vitro Survival of Nonsmall Cell Lung Cancer Cells Following Combined Treatment with Ionizing Radiation and Photofrin-mediated Photodynamic Therapy

Photochemistry and Photobiology. Jan-Feb, 2009  |  Pubmed ID: 18643904

It has been suggested that combination high dose rate (HDR) intraluminal brachytherapy and photodynamic therapy (PDT) in nonsmall cell lung cancer (NSCLC) may improve efficacy of treatment, reduce toxicity and enhance quality of life for patients. To provide a cellular basis for this we examined the in vitro sensitivity of MRC5 normal lung fibroblasts and four NSCLC cell lines following HDR radiation, PDT and combined HDR radiation and PDT. HDR radiation was cobalt-60 gamma rays (1.5-1.9 Gy min(-1)). For PDT treatment, cells were exposed to 2.5 microg mL(-1) Photofrin for 18-24 h followed by light exposure (20 mW cm(-2)). For combined treatment cells were exposed to Photofrin and then either exposed to light and 15-30 min later exposed to HDR radiation or exposed to HDR radiation and 15-30 min later exposed to light. D(37) values calculated from clonogenic survival curves indicated a six-fold difference in HDR radiation sensitivity and an eight-fold difference in PDT sensitivity. The effect of combined treatment was not significantly different from an additive effect of the individual treatment modalities for the NSCLC cells, but was significantly less than additive for the MRC5 cells. These results suggest an equivalent tumor cell kill may be possible at reduced systemic effects to patients.

Elevated Basal and Post-feed Glucagon-like Peptide 1 (GLP-1) Concentrations in the Neonatal Period

European Journal of Endocrinology / European Federation of Endocrine Societies. Jan, 2009  |  Pubmed ID: 18952761

Glucagon-like peptide 1 (GLP-1) is an incretin hormone that stimulates glucose-induced insulin secretion, increases beta-cell proliferation, neogenesis and beta-cell mass. In adults, plasma concentrations of amidated GLP-1 are typically within the 5-10 pmol/l range in the fasting state and increases to approximately 50 pmol/l after ingestion of a mixed meal.

Simple Photodynamic Therapy Dose Models Fail to Predict the Survival of MLL Cells After HPPH-PDT in Vitro

Photochemistry and Photobiology. May-Jun, 2009  |  Pubmed ID: 19140895

Fluorescence photobleaching, photodynamic therapy (PDT) oxygen consumption and clonogenic cell survival were investigated during 2-(1-hexyloxethyl)-2-devinyl pyropheophoribde-a (HPPH) PDT of MAT-LyLu cells in vitro. Cells were incubated with HPPH concentrations of 0.24, 1.2, 3.6 or 12 microm for 4 h and then treated with 650 nm light under oxygenated and hypoxic conditions. Fluorescence spectra were acquired during treatment and photobleaching was quantified using singular value decomposition of the spectra. Cell survival was measured at set times during the treatment using a colony forming assay. Intracellular fluorescence lifetime measurements were also performed at each incubation concentration. The photobleaching kinetics did not follow first- or second-order kinetics and the fluorescence lifetime was similar for all intracellular concentrations. As the intracellular concentration of drug was increased, the amount of singlet oxygen and the absorbed quanta per cell required to achieve the same cell kill increased. Singlet oxygen dose was calculated using one- and two-compartment models of HPPH intracellular distribution. It was found that a two-compartment model, in which a PDT-sensitive binding site saturates at low concentrations, accounts for the observed photobleaching, oxygen consumption and cell survival.

Mice with Hyperghrelinemia Are Hyperphagic and Glucose Intolerant and Have Reduced Leptin Sensitivity

Diabetes. Apr, 2009  |  Pubmed ID: 19151202

Ghrelin is the only known peripheral hormone to increase ingestive behavior. However, its role in the physiological regulation of energy homeostasis is unclear because deletion of ghrelin or its receptor does not alter food intake or body weight in mice fed a normal chow diet. We hypothesized that overexpression of ghrelin in its physiological tissues would increase food intake and body weight.

Peripheral and Central Administration of Xenin and Neurotensin Suppress Food Intake in Rodents

Obesity (Silver Spring, Md.). Jun, 2009  |  Pubmed ID: 19214175

Xenin is a 25-amino acid peptide highly homologous to neurotensin. Xenin and neurotensin are reported to have similar biological effects. Both reduce food intake when administered centrally to fasted rats. We aimed to clarify and compare the effects of these peptides on food intake and behavior. We confirm that intracerebroventricular (ICV) administration of xenin or neurotensin reduces food intake in fasted rats, and demonstrate that both reduce food intake in satiated rats during the dark phase. Xenin reduced food intake more potently than neurotensin following ICV administration. ICV injection of either peptide in the dark phase increased resting behavior. Xenin and neurotensin stimulated the release of corticotrophin-releasing hormone (CRH) from ex vivo hypothalamic explants, and administration of alpha-helical CRH attenuated their effects on food intake. Intraperitoneal (IP) administration of xenin or neurotensin acutely reduced food intake in fasted mice and ad libitum fed mice in the dark phase. However, chronic continuous or twice daily peripheral administration of xenin or neurotensin to mice had no significant effect on daily food intake or body weight. These studies confirm that ICV xenin or neurotensin can acutely reduce food intake and demonstrate that peripheral administration of xenin and neurotensin also reduces food intake. This may be partly mediated by changes in hypothalamic CRH release. The lack of chronic effects on body weight observed in our experiments suggests that xenin and neurotensin are unlikely to be useful as obesity therapies.

Hypothalamic Injection of Oxyntomodulin Suppresses Circulating Ghrelin-like Immunoreactivity

Endocrinology. Aug, 2009  |  Pubmed ID: 19359390

Ghrelin is a gastric peptide that regulates appetite and GH secretion. Circulating ghrelin levels are elevated by fasting and suppressed postprandially. However, the mechanisms regulating circulating ghrelin levels are unclear. Oxyntomodulin is an anorexic peptide hormone released from L cells in the gut. We investigated the effects of intracerebroventricular (icv) administration of oxyntomodulin on circulating ghrelin levels. The icv administration of 1, 3, or 10 nmol oxyntomodulin reduced circulating acylated and total (acylated and des-acylated) ghrelin 60 min after icv injection. Administration of 1 nmol oxyntomodulin directly into the arcuate nucleus of the hypothalamus significantly reduced total and acylated ghrelin levels, and administration of 3 nmol oxyntomodulin into the lateral ventricle induced c-fos mRNA expression in arcuate nucleus neurons expressing the glucagon-like peptide-1 (GLP-1) receptor. In a final study, the reduction in total ghrelin observed after icv injection of 3 nmol oxyntomodulin was blocked by coadministration of the GLP-1 receptor antagonist exendin (9-39). These studies suggest oxyntomodulin reduces peripheral ghrelin levels via GLP-1 receptor-dependent hypothalamic pathways. Postprandial release of anorexic gut hormones may thus act centrally to contribute to the postprandial reduction in circulating ghrelin.

Ghrelin and Peptide YY (PYY) Profiles in Gastrointestinal Tissues and the Circulation of the Rat During Pregnancy and Lactation

Peptides. Dec, 2009  |  Pubmed ID: 19778563

Plasma and tissue profiles of gastrointestinal hormones ghrelin and peptide YY (PYY) were investigated in different female rat reproductive states. Neither plasma nor tissue ghrelin concentrations were suppressed during pregnancy despite elevated leptin. The highest concentrations of stomach ghrelin were measured in late pregnancy. PYY concentrations in plasma, descending colon and rectum tissues were increased (P<0.001) throughout pregnancy and lactation. PYY peaked at day 5 of lactation in plasma, as well as descending colon and rectum tissues (proestrus vs day 5 of lactation: 25+/-3.0 pmol/l vs 55+/-8.0 pmol/l; 85+/-4.5 pmol/g wwt vs 418+/-45.0 pmol/g wwt; 23+/-3.0 pmol/g wwt vs 78+/-9.1 pmol/g wwt). This PYY peak was temporally associated with the luteinizing hormone peak on day 1 of lactation. Following weaning, dam adiposity and plasma leptin increased whereas ghrelin stomach peptide decreased. Relative PYY concentrations in the tissues of the gut varied in the different states suggesting regional alterations taking place in the colon. The ascending colon produced the highest concentrations in non-pregnant rats, the descending colon the highest concentrations during lactation with the pregnant rats and the dams postweaning in a transition state between. It is unclear what role the increased PYY in various tissues observed has during pregnancy and lactation as it would be expected to be reduced in these states of greatly increased appetite. PYY may have an influence on maternal dietary adaptation, intestinal hypertrophy and weight gain during pregnancy and lactation although it is still unclear precisely how it acts.

Are Higher Quality Papers Cited More Often?

Physics in Medicine and Biology. Sep, 2009  |  Pubmed ID: 19798808

Serum Molecular Signatures of Weight Change During Early Breast Cancer Chemotherapy

Clinical Cancer Research : an Official Journal of the American Association for Cancer Research. Nov, 2009  |  Pubmed ID: 19861449

Weight gain in women receiving chemotherapy for breast cancer is associated with a higher risk of recurrence but its mechanisms are poorly understood.

Mutation Analysis in the Long Isoform of USH2A in American Patients with Usher Syndrome Type II

Journal of Human Genetics. Dec, 2009  |  Pubmed ID: 19881469

Usher syndrome type II (USH2) is an autosomal recessive disorder characterized by moderate to severe hearing impairment and progressive visual loss due to retinitis pigmentosa (RP). To identify novel mutations and determine the frequency of USH2A mutations as a cause of USH2, we have carried out mutation screening of all 72 coding exons and exon-intron splice sites of the USH2A gene. A total of 20 USH2 American probands of European descent were analyzed using single strand conformational polymorphism (SSCP) and direct sequencing methods. Ten different USH2A mutations were identified in 55% of the probands, five of which were novel mutations. The detected mutations include three missense, three frameshifts and four nonsense mutations, with c.2299delG/p.E767fs mutation, accounting for 38.9% of the pathological alleles. Two cases were homozygotes, two cases were compound heterozygotes and one case had complex allele with three variants. In seven probands, only one USH2A mutation was detected and no pathological mutation was found in the remaining eight individuals. Altogether, our data support the fact that c.2299delG/p.E767fs is indeed the most common USH2A mutation found in USH2 patients of European Caucasian background. Thus, if screening for mutations in USH2A is considered, it is reasonable to screen for the c.2299delG mutation first.

The Hyperphagic Effect of Ghrelin is Inhibited in Mice by a Diet High in Fat

Gastroenterology. Jun, 2010  |  Pubmed ID: 20178795

Ghrelin is the only peripheral hormone known to increase food intake. It is released from the stomach and is thought to function as a signal of energy deficit and a meal initiator. We generated transgenic mice in which levels of bioactive ghrelin are increased in the stomach and circulation. These mice, as expected, are hyperphagic and glucose intolerant. We investigated whether exposure to a high-fat diet (HFD) would exacerbate this phenotype.

Identification of the Hormone Kisspeptin in Amniotic Fluid

Clinical Chemistry. Jun, 2010  |  Pubmed ID: 20348399

PYY3-36 and Oxyntomodulin Can Be Additive in Their Effect on Food Intake in Overweight and Obese Humans

Diabetes. Jul, 2010  |  Pubmed ID: 20357366

Peptide YY(3-36) (PYY(3-36)), a Y2 receptor agonist, and oxyntomodulin, a glucagon-like peptide 1 (GLP-1) receptor agonist, are cosecreted by intestinal L-cells after each meal. Separately each hormone acts as an endogenous satiety signal and reduces appetite in humans when infused intravenously. The aim of the current study was to investigate whether the anorectic effects of PYY(3-36) and oxyntomodulin can be additive.

Effect of Osteopathy in the Cranial Field on Visual Function--a Pilot Study

The Journal of the American Osteopathic Association. Apr, 2010  |  Pubmed ID: 20430912

The effects of osteopathy in the cranial field on visual function-particularly on changes in the visual field and on the binocular alignment of the eyes-have been poorly characterized in the literature. The authors examined whether osteopathy in the cranial field resulted in an immediate, measurable change in visual function among a sample of adults with cranial asymmetry.

Calculation of Cellular Oxygen Concentration for Photodynamic Therapy in Vitro

Methods in Molecular Biology (Clifton, N.J.). 2010  |  Pubmed ID: 20552349

In vitro photodynamic therapy experiments are usually performed by irradiating cells in confluent or nearly confluent monolayer cultures. Oxygen is consumed in the monolayer by photodynamic reactions and cellular respiration and is supplied by diffusion from the overlying medium. Calculations of oxygen concentration by numerical solution of the time-dependent diffusion equation show that hypoxia can be induced in the monolayer under typical PDT conditions and that this will limit the total treatment effect. There is an optimum fluence rate at which the greatest singlet oxygen dose can be delivered before hypoxia becomes limiting. It is recommended that researchers use these calculations to avoid hypoxia or confirm that fortuitous oxygen transport by other mechanisms (e.g., convection) is adequate to prevent it.

AMPA Receptors Are Exocytosed in Stimulated Spines and Adjacent Dendrites in a Ras-ERK-dependent Manner During Long-term Potentiation

Proceedings of the National Academy of Sciences of the United States of America. Sep, 2010  |  Pubmed ID: 20733080

The exocytosis of AMPA receptors is a key step in long-term potentiation (LTP), yet the timing and location of exocytosis and the signaling pathways involved in exocytosis during synaptic plasticity are not fully understood. Here we combine two-photon uncaging with two-photon imaging of a fluorescent label of surface AMPA receptors to monitor individual AMPA receptor exocytosis events near spines undergoing LTP. AMPA receptors that reached the stimulated spine came from a combination of preexisting surface receptors (70-90%) and newly exocytosed receptors (10-30%). We observed exocytosis in both the dendrite and spine under basal conditions. The rate of AMPA receptor exocytosis increased approximately 5-fold during LTP induction and decayed to the basal level within approximately 1 min, both in the stimulated spine and in the dendrite within approximately 3 microm of the stimulated spine. AMPA receptors inserted in the spine were trapped in the spine in an activity-dependent manner. The activity-dependent exocytosis required the Ras-ERK pathway, but not CaMKII. Thus, diffusive Ras-ERK signaling presumably serves as an important means for signaling from synapses to dendritic shafts to recruit AMPA receptors into synapses during LTP.

A Dynamic Model for ALA-PDT of Skin: Simulation of Temporal and Spatial Distributions of Ground-state Oxygen, Photosensitizer and Singlet Oxygen

Physics in Medicine and Biology. Oct, 2010  |  Pubmed ID: 20844331

Singlet oxygen (¹O₂) direct dosimetry and photosensitizer fluorescence photobleaching are being investigated and applied as dosimetric tools during 5-aminolevulinic acid (ALA)-induced protophorphyrin IX (PpIX) photodynamic therapy (PDT) of normal skin and skin cancers. The correlations of photosensitizer fluorescence and singlet oxygen luminescence (SOL) emission signals to ¹O2 distribution and cumulative ¹O₂dose are difficult to interpret because of the temporal and spatial variations of three essential components (light fluence rate, photosensitizer concentration and oxygen concentration) in PDT. A one-dimensional model is proposed in this paper to simulate the dynamic process of ALA-PDT of normal human skin in order to investigate the time-resolved evolution of PpIX, ground-state oxygen (³O₂and ¹O₂ distributions. The model incorporates a simplified three-layer semi-infinite skin tissue, Monte Carlo simulations of excitation light fluence and both PpIX fluorescence and SOL emission signals reaching the skin surface, ¹O₂-mediated photobleaching mechanism for updating PpIX, ³O₂ and ¹O₂ distributions after the delivery of each light dose increment, ground-state oxygen supply by diffusion from the atmosphere and perfusion from blood vessels, a cumulative ¹O₂-dependent threshold vascular response, and the initial non-uniform distribution of PpIX. The PpIX fluorescence simulated using this model is compared with clinical data reported by Cottrell et al (2008 Clin. Cancer Res. 14 4475-83) for a range of irradiances (10-150 mW cm⁻²). Except for the vascular response, one set of parameters is used to fit data at all irradiances. The time-resolved depth-dependent distributions of PpIX, ³O₂ and ¹O₂ at representative irradiances are presented and discussed in this paper, as well as the PDT-induced vascular response at different depths. Tissue hypoxia and shutdown of oxygen supply occur in the upper dermis, where PpIX is also preserved at the end of treatment.

The Effects of Kisspeptin-54 on Blood Pressure in Humans and Plasma Kisspeptin Concentrations in Hypertensive Diseases of Pregnancy

British Journal of Clinical Pharmacology. Nov, 2010  |  Pubmed ID: 21039761

To investigate (i) if kisspeptin administration alters heart rate (HR) or blood pressure (BP) in healthy male and female volunteers, (ii) whether circulating plasma kisspeptin concentrations in healthy pregnant women and women with hypertensive diseases of pregnancy correlate with BP and (iii) whether women with hypertensive diseases of pregnancy have altered plasma kisspeptin concentrations.

Integrating Spheres for Improved Skin Photodynamic Therapy

Journal of Biomedical Optics. Sep-Oct, 2010  |  Pubmed ID: 21054127

The prescribed radiant exposures for photodynamic therapy (PDT) of superficial skin cancers are chosen empirically to maximize the success of the treatment while minimizing adverse reactions for the majority of patients. They do not take into account the wide range of tissue optical properties for human skin, contributing to relatively low treatment success rates. Additionally, treatment times can be unnecessarily long for large treatment areas if the laser power is not sufficient. Both of these concerns can be addressed by the incorporation of an integrating sphere into the irradiation apparatus. The light fluence rate can be increased by as much as 100%, depending on the tissue optical properties. This improvement can be determined in advance of treatment by measuring the reflectance from the tissue through a side port on the integrating sphere, allowing for patient-specific treatment times. The sphere is also effective at improving beam flatness, and reducing the penumbra, creating a more uniform light field. The side port reflectance measurements are also related to the tissue transport albedo, enabling an approximation of the penetration depth, which is useful for real-time light dosimetry.

Algorithms for Bioluminescence Tomography Incorporating Anatomical Information and Reconstruction of Tissue Optical Properties

Biomedical Optics Express. 2010  |  Pubmed ID: 21258486

Reconstruction algorithms are presented for a two-step solution of the bioluminescence tomography (BLT) problem. In the first step, a priori anatomical information provided by x-ray computed tomography or by other methods is used to solve the continuous wave (cw) diffuse optical tomography (DOT) problem. A Taylor series expansion approximates the light fluence rate dependence on the optical properties of each region where first and second order direct derivatives of the light fluence rate with respect to scattering and absorption coefficients are obtained and used for the reconstruction. In the second step, the reconstructed optical properties at different wavelengths are used to calculate the Green's function of the system. Then an iterative minimization solution based on the L1 norm shrinks the permissible regions where the sources are allowed by selecting points with higher probability to contribute to the source distribution. This provides an efficient BLT reconstruction algorithm with the ability to determine relative source magnitudes and positions in the presence of noise.

Improved Bioluminescence and Fluorescence Reconstruction Algorithms Using Diffuse Optical Tomography, Normalized Data, and Optimized Selection of the Permissible Source Region

Biomedical Optics Express. 2010  |  Pubmed ID: 21326647

Reconstruction algorithms are presented for two-step solutions of the bioluminescence tomography (BLT) and the fluorescence tomography (FT) problems. In the first step, a continuous wave (cw) diffuse optical tomography (DOT) algorithm is used to reconstruct the tissue optical properties assuming known anatomical information provided by x-ray computed tomography or other methods. Minimization problems are formed based on L1 norm objective functions, where normalized values for the light fluence rates and the corresponding Green's functions are used. Then an iterative minimization solution shrinks the permissible regions where the sources are allowed by selecting points with higher probability to contribute to the source distribution. Throughout this process the permissible region shrinks from the entire object to just a few points. The optimum reconstructed bioluminescence and fluorescence distributions are chosen to be the results of the iteration corresponding to the permissible region where the objective function has its global minimum This provides efficient BLT and FT reconstruction algorithms without the need for a priori information about the bioluminescence sources or the fluorophore concentration. Multiple small sources and large distributed sources can be reconstructed with good accuracy for the location and the total source power for BLT and the total number of fluorophore molecules for the FT. For non-uniform distributed sources, the size and magnitude become degenerate due to the degrees of freedom available for possible solutions. However, increasing the number of data points by increasing the number of excitation sources can improve the accuracy of reconstruction for non-uniform fluorophore distributions.

Two Streams Make a River: the Rabbit in Richard F. Thompson's Laboratory

Neurobiology of Learning and Memory. Feb, 2011  |  Pubmed ID: 21111838

The rabbit nictitating membrane (NM) preparation was developed in 1962 by Gormezano as a model system for classical conditioning. It had many features that made it ideal for use in exploring the laws of this conditioning paradigm, including easily obtainable subjects, good control of stimulus delivery and precise response specifications. Most importantly, the preparation evidenced very low spontaneous response rates and showed no evidence of nonassociative effects of sensitization and pseudoconditioning and had highly predictable learning functions. In contrast, previous human and animal models that had been utilized to explore the features of classical conditioning, such as the dog salivary model were far less easy to use, showed high spontaneous response rates, and had high nonassociative components. Over the ensuing years, Gormezano and his students characterized most of the parametric characteristics of classical conditioning with the use of the preparation. In 1970, Richard Thompson began exploring the use of the rabbit NM preparation in his laboratory as a model system with which to explore the brain substrates of classical conditioning. At the time, his work was centered around exploring the neural substrates of sensitization and habituation in spinal reflexes. Soon, however, he turned his attention to the brain substrates of classical conditioning almost exclusively, and produced an impressive amount of data detailing the neural underpinnings of classical conditioning. His work has generated perhaps the most detailed and complete picture of the neural mechanisms of learning currently available, and has led to countless other research efforts in the area of brain and behavior. Current understandings of neural mechanisms of associative learning owe much to Thompson and his various colleagues.

The Influence of Oxygen Depletion and Photosensitizer Triplet-state Dynamics During Photodynamic Therapy on Accurate Singlet Oxygen Luminescence Monitoring and Analysis of Treatment Dose Response

Photochemistry and Photobiology. Jan-Feb, 2011  |  Pubmed ID: 21143603

To date, singlet oxygen ((1)O(2)) luminescence (SOL) detection was predictive of photodynamic therapy (PDT) treatment responses both in vitro and in vivo, but accurate quantification is challenging. In particular, the early and strongest part of the time-resolved signal (500-2000ns) is difficult to separate from confounding sources of luminescence and system noise, and so is normally gated out. However, the signal dynamics change with oxygen depletion during PDT, so that this time gating biases the (1)O(2) measurements. Here, the impact of gating was investigated in detail, determining the rate constants from SOL and direct pO(2) measurements during meso-tetra(hydroxyphenyl)chlorin (mTHPC)-mediated PDT of cells in vitro under well-controlled conditions. With these data as input, numerical simulations were used to examine PDT and SOL dynamics, and the influence of various time gates on cumulative SOL signals. It is shown that gating can underestimate the SOL at early treatment time points by ∼40% and underestimate the cumulative SOL signal by 20-25%, representing significant errors. In vitro studies with both mTHPC and aminolevulinic acid-photosensitizer protoporphyrin IX demonstrate that rigorous analysis of SOL signal kinetics is then crucial in order to use SOL as an accurate and quantitative PDT dose metric.

The Nutriceutical Bovine Colostrum Truncates the Increase in Gut Permeability Caused by Heavy Exercise in Athletes

American Journal of Physiology. Gastrointestinal and Liver Physiology. Mar, 2011  |  Pubmed ID: 21148400

Heavy exercise causes gut symptoms and, in extreme cases, "heat stroke" partially due to increased intestinal permeability of luminal toxins. We examined bovine colostrum, a natural source of growth factors, as a potential moderator of such effects. Twelve volunteers completed a double-blind, placebo-controlled, crossover protocol (14 days colostrum/placebo) prior to standardized exercise. Gut permeability utilized 5 h urinary lactulose-to-rhamnose ratios. In vitro studies (T84, HT29, NCM460 human colon cell lines) examined colostrum effects on temperature-induced apoptosis (active caspase-3 and 9, Baxα, Bcl-2), heat shock protein 70 (HSP70) expression and epithelial electrical resistance. In both study arms, exercise increased blood lactate, heart rate, core temperature (mean 1.4°C rise) by similar amounts. Gut hormone profiles were similar in both arms although GLP-1 levels rose following exercise in the placebo but not the colostrum arm (P = 0.026). Intestinal permeability in the placebo arm increased 2.5-fold following exercise (0.38 ± 0.012 baseline, to 0.92 ± 0.014, P < 0.01), whereas colostrum truncated rise by 80% (0.38 ± 0.012 baseline to 0.49 ± 0.017) following exercise. In vitro apoptosis increased by 47-65% in response to increasing temperature by 2°C. This effect was truncated by 60% if colostrum was present (all P < 0.01). Similar results were obtained examining epithelial resistance (colostrum truncated temperature-induced fall in resistance by 64%, P < 0.01). Colostrum increased HSP70 expression at both 37 and 39°C (P < 0.001) and was truncated by addition of an EGF receptor-neutralizing antibody. Temperature-induced increase in Baxα and reduction in Bcl-2 was partially reversed by presence of colostrum. Colostrum may have value in enhancing athletic performance and preventing heat stroke.

TRPV4-mediated Calcium Influx into Human Bronchial Epithelia Upon Exposure to Diesel Exhaust Particles

Environmental Health Perspectives. Jun, 2011  |  Pubmed ID: 21245013

Human respiratory epithelia function in airway mucociliary clearance and barrier function and have recently been implicated in sensory functions.

Signalling Pathways Underlying Structural Plasticity of Dendritic Spines

British Journal of Pharmacology. Aug, 2011  |  Pubmed ID: 21410464

Synaptic plasticity, or changes in synaptic strength, is thought to underlie learning and memory. Imaging studies, mainly in brain slices, have revealed that long-term synaptic plasticity of excitatory synapses in hippocampal neurons is coupled with structural plasticity of dendritic spines, which is thought to be essential for inducing and regulating functional plasticity. Using pharmacological and genetic manipulation, the signalling network underlying structural plasticity has been extensively studied. Furthermore, the recent advent of fluorescence resonance energy transfer (FRET) imaging techniques has provided a readout of the dynamics of signal transduction in dendritic spines undergoing structural plasticity. These studies reveal the signalling pathways relaying Ca(2+) to the functional and structural plasticity of dendritic spines.

Calculation of Singlet Oxygen Dose Using Explicit and Implicit Dose Metrics During Benzoporphyrin Derivative Monoacid Ring A (BPD-MA)-PDT in Vitro and Correlation with MLL Cell Survival

Photochemistry and Photobiology. Sep-Oct, 2011  |  Pubmed ID: 21575000

Photodynamic therapy (PDT) oxygen consumption, clonogenic cell survival, fluorescence photobleaching and photoproduct formation were investigated during benzoporphyrin derivative monoacid (BPD-MA)-PDT of MAT-LyLu cells in vitro. Cells were incubated with BPD-MA concentrations of 0.1, 0.5 or 2.5 μg mL(-1) for 2 h and then treated with 405 nm light under oxygenated and hypoxic conditions. Fluorescence spectra were acquired during treatment, and photobleaching and photoproduct generation were quantified using singular value decomposition of the spectra. Cell survival was measured at set times during the treatment using a colony-forming assay. The amount of oxygen consumed by PDT per photon absorbed decreased with BPD-MA intracellular concentration. Survival was correlated with the total amount of oxygen consumed by PDT per unit volume, which is assumed to be equivalent to the amount of singlet oxygen that reacted. A photobleaching-based singlet oxygen dose metric was also found to predict survival independent of intracellular BPD-MA concentration. The BPD-MA photoproduct was bleached during the treatment. Two singlet oxygen dose metrics based on photoproduct kinetics could not be correlated with cell survival over the full range of intracellular BPD-MA concentrations used.

Orexin A (hypocretin-1) Levels Are Not Reduced While Cocaine/amphetamine Regulated Transcript Levels Are Increased in the Cerebrospinal Fluid of Patients with Multiple Sclerosis: No Correlation with Fatigue and Sleepiness

Journal of the Neurological Sciences. Aug, 2011  |  Pubmed ID: 21605873

Fatigue and sleep disturbance are common features of multiple sclerosis (MS). Our objectives were to determine cerebrospinal fluid levels of orexin A (hypocretin-1), a hypothalamic peptide involved in sleep, in patients with MS, and correlate them with fatigue, sleepiness, and levels of cocaine and amphetamine regulated transcript (CART) another neuropeptide regulating metabolism with wider nervous system distribution.

Ghrelin and Appetite Control in Humans--potential Application in the Treatment of Obesity

Peptides. Nov, 2011  |  Pubmed ID: 21835215

Ghrelin is a peptide hormone secreted into circulation from the stomach. It has been postulated to act as a signal of hunger. Ghrelin administration acutely increases energy intake in lean and obese humans and chronically induces weight gain and adiposity in rodents. Circulating ghrelin levels are elevated by fasting and suppressed following a meal. Inhibiting ghrelin signaling therefore appears an attractive target for anti-obesity therapies. A number of different approaches to inhibiting the ghrelin system to treat obesity have been explored. Despite this, over a decade after its discovery, no ghrelin based anti-obesity therapies are close to reaching the market. This article discusses the role of ghrelin in appetite control in humans, examines different approaches to inhibiting the ghrelin system and assesses their potential as anti-obesity therapies.

Rapid, Non-invasive Imaging of Alphaviral Brain Infection: Reducing Animal Numbers and Morbidity to Identify Efficacy of Potential Vaccines and Antivirals

Vaccine. Nov, 2011  |  Pubmed ID: 22001884

Rapid and accurate identification of disease progression are key factors in testing novel vaccines and antivirals against encephalitic alphaviruses. Typical efficacy studies utilize a large number of animals and severe morbidity or mortality as an endpoint. New technologies provide a means to reduce and refine the animal use as proposed in Hume's 3Rs (replacement, reduction, refinement) described by Russel and Burch. In vivo imaging systems (IVIS) and bioluminescent enzyme technologies accomplish the reduction of animal requirements while shortening the experimental time and improving the accuracy in localizing active virus replication. In the case of murine models of viral encephalitis in which central nervous system (CNS) viral invasion occurs rapidly but the disease development is relatively slow, we visualized the initial brain infection and enhance the data collection process required for efficacy studies on antivirals or vaccines that are aimed at preventing brain infection. Accordingly, we infected mice through intranasal inoculation with the genetically modified pathogen, Venezuelan equine encephalitis, which expresses a luciferase gene. In this study, we were able to identify the invasion of the CNS at least 3 days before any clinical signs of disease, allowing for reduction of animal morbidity providing a humane means of disease and vaccine research while obtaining scientific data accurately and more rapidly. Based on our data from the imaging model, we confirmed the usefulness of this technology in preclinical research by demonstrating the efficacy of Ampligen, a TLR-3 agonist, in preventing CNS invasion.

Lack of Association Between Impaired Glucose Tolerance and Appetite Regulating Hormones in Patients with Obstructive Sleep Apnea

Journal of Clinical Sleep Medicine : JCSM : Official Publication of the American Academy of Sleep Medicine. Oct, 2011  |  Pubmed ID: 22003344

Understanding the etiologic mechanisms underlying impaired glucose tolerance in obstructive sleep apnea (OSA) would assist development of therapies against this comorbidity. We hypothesized that in patients with OSA impaired glucose tolerance (IGT) would be associated with elevated levels of hormones associated with appetite regulation (leptin, ghrelin, neuropeptide Y [NPY] and peptide tyrosine-tyrosine [PYY]).

Bioluminescence Tomography Using Eigenvectors Expansion and Iterative Solution for the Optimized Permissible Source Region

Biomedical Optics Express. Nov, 2011  |  Pubmed ID: 22076277

A reconstruction algorithm for bioluminescence tomography (BLT) has been developed. The algorithm numerically calculates the Green's function at different wavelengths using the diffusion equation and finite element method. The optical properties used in calculating the Green's function are reconstructed using diffuse optical tomography (DOT) and assuming anatomical information is provided by x-ray computed tomography or other methods. A symmetric system of equations is formed using the Green's function and the measured light fluence rate and the resulting eigenvalue problem is solved to get the eigenvectors of this symmetric system of equations. A space can be formed from the eigenvectors obtained and the reconstructed source is written as an expansion of the eigenvectors corresponding to non-zero eigenvalues. The coefficients of the expansion are found to obtain the reconstructed BL source distribution. The problem is solved iteratively by using a permissible source region that is shrunk by removing nodes with low probability to contribute to the source. Throughout this process the permissible region shrinks from the entire object to just a few nodes. The best estimate of the reconstructed source is chosen that which minimizes the difference between the calculated and measured light fluence rates. 3D simulations presented here show that the reconstructed source is in good agreement with the actual source in terms of locations, magnitudes, sizes, and total powers for both localized multiple sources and large inhomogeneous source distributions.

Medical Physics Staffing for Radiation Oncology: a Decade of Experience in Ontario, Canada

Journal of Applied Clinical Medical Physics / American College of Medical Physics. 2012  |  Pubmed ID: 22231223

The January 2010 articles in The New York Times generated intense focus on patient safety in radiation treatment, with physics staffing identified frequently as a critical factor for consistent quality assurance. The purpose of this work is to review our experience with medical physics staffing, and to propose a transparent and flexible staffing algorithm for general use. Guided by documented times required per routine procedure, we have developed a robust algorithm to estimate physics staffing needs according to center-specific workload for medical physicists and associated support staff, in a manner we believe is adaptable to an evolving radiotherapy practice. We calculate requirements for each staffing type based on caseload, equipment inventory, quality assurance, educational programs, and administration. Average per-case staffing ratios were also determined for larger-scale human resource planning and used to model staffing needs for Ontario, Canada over the next 10 years. The workload specific algorithm was tested through a survey of Canadian cancer centers. For center-specific human resource planning, we propose a grid of coefficients addressing specific workload factors for each staff group. For larger scale forecasting of human resource requirements, values of 260, 700, 300, 600, 1200, and 2000 treated cases per full-time equivalent (FTE) were determined for medical physicists, physics assistants, dosimetrists, electronics technologists, mechanical technologists, and information technology specialists, respectively.

Comparison of Noninvasive Photodynamic Therapy Dosimetry Methods Using a Dynamic Model of ALA-PDT of Human Skin

Physics in Medicine and Biology. Feb, 2012  |  Pubmed ID: 22251621

A numerical model of ALA photodynamic therapy of human skin was used to calculate photosensitizer fluorescence and singlet-oxygen luminescence (SOL) observable at the skin surface during treatment. From the emissions, three practical dose metrics were calculated: the fractional fluorescence bleaching metric (FFBM) given by F(0)/F, where F is photosensitizer protoporphyrin IX (PpIX) fluorescence and F(0) is its initial value, the absolute fluorescence bleaching metric (AFBM) given by F(0)-F, and the cumulative SOL (CSOL). These three metrics can be measured during clinical PDT treatment, but their relation to actual singlet-oxygen distribution in the skin is complex and may depend on treatment parameters such as irradiance. Using the model, the three metrics were compared to the average singlet-oxygen dose in the dermis. Despite the complex dependence of (1)O(2) concentration on depth, a roughly linear correlation was found for all three dose metrics. The correlation for the FFBM was not robust when treatment parameters were varied and this metric was especially sensitive to the initial PpIX concentration and its depth dependence. The AFBM was less sensitive to treatment conditions but CSOL demonstrated the best overall performance.

Insights into Photodynamic Therapy Dosimetry: Simultaneous Singlet Oxygen Luminescence and Photosensitizer Photobleaching Measurements

Biophysical Journal. Feb, 2012  |  Pubmed ID: 22325290

Photodynamic therapy (PDT) is generally based on the generation of highly reactive singlet oxygen ((1)O(2)) through interactions of photosensitizer, light, and oxygen ((3)O(2)). These three components are highly interdependent and dynamic, resulting in variable temporal and spatial (1)O(2) dose deposition. Robust dosimetry that accounts for this complexity could improve treatment outcomes. Although the 1270 nm luminescence emission from (1)O(2) provides a direct and predictive PDT dose metric, it may not be clinically practical. We used (1)O(2) luminescence (or singlet oxygen luminescence (SOL)) as a gold-standard metric to evaluate potentially more clinically feasible dosimetry based on photosensitizer bleaching. We performed in vitro dose-response studies with simultaneous SOL and photosensitizer fluorescence measurements under various conditions, including variable (3)O(2), using the photosensitizer meta-tetra(hydroxyphenyl)chlorin (mTHPC). The results show that SOL was always predictive of cytotoxicity and immune to PDT's complex dynamics, whereas photobleaching-based dosimetry failed under hypoxic conditions. However, we identified a previously unreported 613 nm emission from mTHPC that indicates critically low (3)O(2) levels and can be used to salvage photobleaching-based dosimetry. These studies improve our understanding of PDT processes, demonstrate that SOL is a valuable gold-standard dose metric, and show that when used judiciously, photobleaching can serve as a surrogate for (1)O(2) dose.

Plasma Kisspeptin Levels in Pregnancies with Diabetes and Hypertensive Disease As a Potential Marker of Placental Dysfunction and Adverse Perinatal Outcome

Endocrine Research. 2012  |  Pubmed ID: 22489921

The aim of this study was to prospectively evaluate plasma kisspeptin levels in 129 singleton pregnancies with diabetes [pregestational insulin-dependent diabetes mellitus (type 1) and gestational diabetes (GD)] and hypertensive disease [chronic hypertension (CH), gestational hypertension, and preeclampsia (PE)] as a potential marker of placental dysfunction and adverse perinatal outcome.

Natural Killer Cell Mediated Pathogenesis Determines Outcome of Central Nervous System Infection with Venezuelan Equine Encephalitis Virus in C3H/HeN Mice

Vaccine. Jun, 2012  |  Pubmed ID: 22525795

TC83 is a human vaccine with investigational new drug status and is used as a prototype Venezuelan equine encephalitis virus for pathogenesis and antiviral research. Differing from other experimental models, the virus causes high titer infection in the brain and 90-100% mortality in the C3H/HeN murine model. To better characterize the susceptibility to disease development in C3H/HeN mice, we have analyzed the gene transcriptomes and cytokine production in the brains of infected mice. Our analysis indicated the potential importance of natural killer cells in the encephalitic disease development. This paper describes for the first time a pathogenic role for natural killer cells in VEEV encephalitis.

Rigor in Medical Writing: Quoting Accurately

The Journal of the American Osteopathic Association. Jun, 2012  |  Pubmed ID: 22707641

Cervical Spine Bending: a Factor Confounding Whole Trunk and Lumbar Forward Bending Range of Motion

The Journal of the American Osteopathic Association. Jul, 2012  |  Pubmed ID: 22802543

Knee bending during tests of lumbar forward bending (FB) may introduce confounding variability. Precluding bending at the knees has, therefore, long been standard protocol to produce valid and reproducible results. However, there is limited research on cervical spine bending as a confounding variable in whole trunk and lumbar FB.

Touch: Vital to Patient-physician Relationships

The Journal of the American Osteopathic Association. Aug, 2012  |  Pubmed ID: 22904245

Monitoring Photosensitizer Uptake Using Two Photon Fluorescence Lifetime Imaging Microscopy

Theranostics. 2012  |  Pubmed ID: 23082095

Photodynamic Therapy (PDT) provides an opportunity for treatment of various invasive tumors by the use of a cancer targeting photosensitizing agent and light of specific wavelengths. However, real-time monitoring of drug localization is desirable because the induction of the phototoxic effect relies on interplay between the dosage of localized drug and light. Fluorescence emission in PDT may be used to monitor the uptake process but fluorescence intensity is subject to variability due to scattering and absorption; the addition of fluorescence lifetime may be beneficial to probe site-specific drug-molecular interactions and cell damage. We investigated the fluorescence lifetime changes of Photofrin(®) at various intracellular components in the Mat-LyLu (MLL) cell line. The fluorescence decays were analyzed using a bi-exponential model, followed by segmentation analysis of lifetime parameters. When Photofrin(®) was localized at the cell membrane, the slow lifetime component was found to be significantly shorter (4.3 ± 0.5 ns) compared to those at other locations (cytoplasm: 7.3 ± 0.3 ns; mitochondria: 7.0 ± 0.2 ns, p < 0.05).

Self-calibrated Algorithms for Diffuse Optical Tomography and Bioluminescence Tomography Using Relative Transmission Images

Biomedical Optics Express. Nov, 2012  |  Pubmed ID: 23162719

Reconstruction algorithms for diffuse optical tomography (DOT) and bioluminescence tomography (BLT) have been developed based on diffusion theory. The algorithms numerically solve the diffusion equation using the finite element method. The direct measurements of the uncalibrated light fluence rates by a camera are used for the reconstructions. The DOT is self-calibrated by using all possible pairs of transmission images obtained with external sources along with the relative values of the simulated data and the calculated Jacobian. The reconstruction is done in the relative domain with the cancelation of any geometrical or optical factors. The transmission measurements for the DOT are used for calibrating the bioluminescence measurements at each wavelength and then a normalized system of equations is built up which is self-calibrated for the BLT. The algorithms have been applied to a three dimensional model of the mouse (MOBY) segmented into tissue regions which are assumed to have uniform optical properties. The DOT uses the direct method for calculating the Jacobian. The BLT uses a reduced space of eigenvectors of the Green's function with iterative shrinking of the permissible source region. The reconstruction results of the DOT and BLT algorithms show good agreement with the actual values when using either absolute or relative data. Even a small calibration error causes significant degradation of the reconstructions based on absolute data.

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