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Find video protocols related to scientific articles indexed in Pubmed.
Development of a physiologically based model to describe the pharmacokinetics of methylphenidate in juvenile and adult humans and nonhuman primates.
PLoS ONE
PUBLISHED: 09-03-2014
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The widespread usage of methylphenidate (MPH) in the pediatric population has received considerable attention due to its potential effect on child development. For the first time a physiologically based pharmacokinetic (PBPK) model has been developed in juvenile and adult humans and nonhuman primates to quantitatively evaluate species- and age-dependent enantiomer specific pharmacokinetics of MPH and its primary metabolite ritalinic acid. The PBPK model was first calibrated in adult humans using in vitro enzyme kinetic data of MPH enantiomers, together with plasma and urine pharmacokinetic data with MPH in adult humans. Metabolism of MPH in the small intestine was assumed to account for the low oral bioavailability of MPH. Due to lack of information, model development for children and juvenile and adult nonhuman primates primarily relied on intra- and interspecies extrapolation using allometric scaling. The juvenile monkeys appear to metabolize MPH more rapidly than adult monkeys and humans, both adults and children. Model prediction performance is comparable between juvenile monkeys and children, with average root mean squared error values of 4.1 and 2.1, providing scientific basis for interspecies extrapolation of toxicity findings. Model estimated human equivalent doses in children that achieve similar internal dose metrics to those associated with pubertal delays in juvenile monkeys were found to be close to the therapeutic doses of MPH used in pediatric patients. This computational analysis suggests that continued pharmacovigilance assessment is prudent for the safe use of MPH.
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Angiogenesis and airway reactivity in asthmatic Brown Norway rats.
Angiogenesis
PUBLISHED: 08-23-2014
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Expanded and aberrant bronchial vascularity, a prominent feature of the chronic asthmatic airway, might explain persistent airway wall edema and sustained leukocyte recruitment. Since it is well established that there are causal relationships between exposure to house dust mite (HDM) and the development of asthma, determining the effects of HDM in rats, mammals with a bronchial vasculature similar to humans, provides an opportunity to study the effects of bronchial angiogenesis on airway function directly. We studied rats exposed bi-weekly to HDM (Der p 1; 50 ?g/challenge by intranasal aspiration, 1, 2, 3 weeks) and measured the time course of appearance of increased blood vessels within the airway wall. Results demonstrated that within 3 weeks of HDM exposure, the number of vessels counted within airway walls of bronchial airways (0.5-3 mm perimeter) increased significantly. These vascular changes were accompanied by increased airway responsiveness to methacholine. A shorter exposure regimen (2 weeks of bi-weekly exposure) was insufficient to cause a significant increase in functional vessels or reactivity. Yet, (19)F/(1)H MR imaging at 3T following ?v?3-targeted perfluorocarbon nanoparticle infusion revealed a significant increase in (19)F signal in rat airways after 2 weeks of bi-weekly HDM, suggesting earlier activation of the process of neovascularization. Although many antigen-induced mouse models exist, mice lack a bronchial vasculature and consequently lack the requisite human parallels to study bronchial edema. Overall, our results provide an important new model to study the impact of bronchial angiogenesis on chronic inflammation and airways hyperreactivity.
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Effect of edaravone on radiation-induced brain necrosis in patients with nasopharyngeal carcinoma after radiotherapy: a randomized controlled trial.
J. Neurooncol.
PUBLISHED: 08-21-2014
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Excessive generation of free radicals plays a critical role in the pathogenesis of radiation-induced brain injury. This study was designed to evaluate the protective effect of edaravone, a free radical scavenger, on radiation-induced brain necrosis in patients with nasopharyngeal carcinoma. Eligible patients were randomized 1:1 to the control group and the edaravone group (intravenous 30 mg twice per day for 2 weeks). Both groups received intravenous conventional steroid therapy and were monitored by brain MRI and LENT/SOMA scales prior to the entry of the trial and at 3-months after completing the trial. The primary end point was a 3-month response rate of the proportional changes determined by MRI. The trial is registered at Clinicaltrials.gov Identifier: NCT01865201. Between 2009 and 2012, we enrolled 154 patients. Of whom 137 were eligible for analysis. The volumes of necrosis estimated on T2-weighted image showed that 55.6 % edaravone-treated patients (40 out of 72) showed edema decreases ?25 %, which was significantly higher than that in the control group (35.4 %, 23 out of 65, p = 0.025). Forty-four patients treated with edaravone (61.1 %) reported improvement in neurologic symptoms and signs evaluated by LENT/SOMA scales, while the rate was 38.5 % in the control group (p = 0.006). MRI of the edaravone group showed a significant decrease in area of T1-weighted contrast enhancement (1.67 ± 4.69 cm(2), p = 0.004) and the T2-weighted edema (5.08 ± 10.32 cm(2), p = 0.000). Moreover, compared with those in control group, patients with edaravone exhibited significantly better radiological improvement measured by T2-weighted image (p = 0.042). Administration of edaravone, in adjunct to steroid regimen, might provide a better outcome in patients with radiation-induced brain necrosis.
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Fumagillin prodrug nanotherapy suppresses macrophage inflammatory response via endothelial nitric oxide.
ACS Nano
PUBLISHED: 06-24-2014
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Antiangiogenesis has been extensively explored for the treatment of a variety of cancers and certain inflammatory processes. Fumagillin, a mycotoxin produced by Aspergillus fumigatus that binds methionine aminopeptidase 2 (MetAP-2), is a potent antiangiogenic agent. Native fumagillin, however, is poorly soluble and extremely unstable. We have developed a lipase-labile fumagillin prodrug (Fum-PD) that eliminated the photoinstability of the compound. Using ?v?3-integrin-targeted perfluorocarbon nanocarriers to deliver Fum-PD specifically to angiogenic vessels, we effectively suppressed clinical disease in an experimental model of rheumatoid arthritis (RA). The exact mechanism by which Fum-PD-loaded targeted nanoparticles suppressed inflammation in experimental RA, however, remained unexplained. We herein present evidence that Fum-PD nanotherapy indirectly suppresses inflammation in experimental RA through the local production of endothelial nitric oxide (NO). Fum-PD-induced NO activates AMP-activated protein kinase (AMPK), which subsequently modulates macrophage inflammatory response. In vivo, NO-induced AMPK activation inhibits mammalian target of rapamycin (mTOR) activity and enhances autophagic flux, as evidenced by p62 depletion and increased autolysosome formation. Autophagy in turn mediates the degradation of IkappaB kinase (IKK), suppressing the NF-?B p65 signaling pathway and inflammatory cytokine release. Inhibition of NO production by N(G)-nitro-L-arginine methyl ester (L-NAME), a nitric oxide synthase inhibitor, reverses the suppression of NF-?B-mediated inflammatory response induced by Fum-PD nanotherapy. These unexpected results uncover an activity of Fum-PD nanotherapy that may be further explored in the treatment of angiogenesis-dependent diseases.
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Plasmonic extinction of gated graphene nanoribbon array analyzed by a scaled uniform Fermi level.
Opt Lett
PUBLISHED: 04-03-2014
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A uniform Fermi level profile is typically assumed in the analysis of a gated graphene nanoribbon, whose Fermi level is actually nonuniform in the experimental measurements. Here, we show that the uniform Fermi level has to be downshifted when it is used to analyze a backgated graphene nanoribbon array (GNRA). The plasmonic extinction behaviors of the GNRAs are perfectly preserved by assuming properly scaled uniform Fermi levels. The scaling factor is independent of the average value of the actual Fermi level profile, but it is a function of the ratio of the nanoribbon width to the distance of the nanoribbons from the backgate. This study facilitates the data postprocessing in the experiments, and may be helpful for analyzing the electron behaviors in GNRAs.
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Engineering of a novel anti-CD40L domain antibody for treatment of autoimmune diseases.
J. Immunol.
PUBLISHED: 03-26-2014
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CD40-CD40L interactions play a critical role in regulating immune responses. Blockade of CD40L by Abs, such as the anti-CD40L Ab 5c8, demonstrated positive clinical effects in patients with autoimmune diseases; however, incidents of thromboembolism (TE) precluded further development of these molecules. In this study, we examined the role of the Fc domain interaction with Fc?Rs in modulating platelet activation and potential for TE. Our results show that the interaction of the 5c8 wild-type IgG1 Fc domain with Fc?Rs is responsible for platelet activation, as measured by induction of PAC-1 and CD62P. A version of 5c8 with a mutated IgG1 tail was identified that showed minimal Fc?R binding and platelet activation while maintaining full binding to CD40L. To address whether Fc effector function is required for immunosuppression, a potent Ab fragment, termed a "domain Ab" (dAb), against murine CD40L was identified and fused to a murine IgG1 Fc domain containing a D265A mutation that lacks Fc effector function. In vitro, this dAb-Fc demonstrated comparable potency to the benchmark mAb MR-1 in inhibiting B cell and dendritic cell activation. Furthermore, the anti-CD40L dAb-Fc exhibited a notable efficacy comparable to MR-1 in various preclinical models, such as keyhole limpet hemocyanin-induced Ab responses, alloantigen-induced T cell proliferation, "heart-to-ear" transplantation, and NZB × NZW F1 spontaneous lupus. Thus, our data show that immunosuppression and TE can be uncoupled and that a CD40L dAb with an inert Fc tail is expected to be efficacious for treating autoimmune diseases, with reduced risk for TE.
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Substrate Phonon-Mediated Plasmon Hybridization in Coplanar Graphene Nanostructures for Broadband Plasmonic Circuits.
Small
PUBLISHED: 02-25-2014
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The mode hybridization between adjacent graphene nanoribbons determines the integration density of graphene-based plasmonic devices. Here, plasmon hybridization in graphene nanostructures is demonstrated through the characterization of the coupling strength of plasmons in graphene nanoribbons as a function of charge density and inter-ribbon spacing using Fourier transform infrared microscopy. In combination with numerical simulations, it is shown that the plasmon coupling is strongly mediated by the substrate phonons. For polar substrates, the plasmon coupling strength is limited by the plasmon-phonon interactions. In contrast, a nonpolar substrate affects neither the energy distribution of the original plasmon modes in graphene nanostructures nor their plasmon interactions, which increases exponentially as the inter-ribbon spacing decreases. To further explore the potential of graphene broadband plasmonics on nonpolar substrates, a scheme is proposed that uses a metal-dielectric heterostructure to prevent the overlap of plasmons between neighboring graphene nanoribbons. The device structures retain the plasmon resonance frequency of the graphene ribbons and maximally isolate the plasmonic components from the surrounding electromagnetic environment, allowing modular design in integrated plasmonic circuits.
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Mechanical and dye adsorption properties of graphene oxide/chitosan composite fibers prepared by wet spinning.
Carbohydr Polym
PUBLISHED: 02-11-2014
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Graphene oxide/chitosan composite fibers were prepared by a wet spinning method, and their mechanical properties were investigated. Experimental results showed that the introduction of graphene oxide at 4 wt% loading can improve the tensile strengths of chitosan fibers. Batch adsorption experiments were carried out to study the effect of various parameters, such as the initial pH value, adsorbent dosage, contact time and temperature on adsorption of fuchsin acid dye. The Langmuir model was used to fit the experimental data of adsorption isotherm, and kinetic studies showed that the adsorption data followed the pseudo-second order model. Thermodynamic studies indicated that the adsorption of fuchsin acid dye on graphene oxide/chitosan fibers was a spontaneous and exothermic process. Our results indicate that the graphene oxide/chitosan fibers have excellent mechanical properties and can serve as a promising adsorbent for the removal of dyes from aqueous solutions.
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Highly efficient orange and warm white phosphorescent OLEDs based on a host material with a carbazole-fluorenyl hybrid.
Chem Asian J
PUBLISHED: 01-28-2014
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A new carbazole-fluorenyl hybrid compound, 3,3'(2,7-di(naphthaline-2-yl)-9H-fluorene-9,9-diyl)bis(9-phenyl-9H-carbazole) (NFBC) was synthesized and characterized. The compound exhibits blue-violet emission both in solution and in film, with peaks centered at 404 and 420?nm. In addition to the application as a blue emitter, NFBC is demonstrated to be a good host for phosphorescent dopants. By doping Ir(2-phq)3 in NFBC, a highly efficient orange organic light-emitting diode (OLED) with a maximum efficiency of 32?cd?A(-1) (26.5?Lm?W(-1)) was obtained. Unlike most phosphorescent OLEDs, the device prepared in our study shows little efficiency roll-off at high brightness and maintains current efficiencies of 31.9 and 26.8?cd?A(-1) at a luminance of 1000 and 10,000?cd?m(-2), respectively. By using NFBC simultaneously as a blue fluorescence emitter and as a host for a phosphorescent dopant, a warm white OLED with a maximum efficiency of 22.9?Lm?W(-1) (21.9?cd?A(-1)) was also obtained.
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The hypothalamic-pituitary-thyroid axis in infants and children: protection from radioiodines.
J Thyroid Res
PUBLISHED: 01-10-2014
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Potassium iodide (KI) is recommended as an emergency treatment for exposure to radioiodines, most commonly associated with nuclear detonation or mishaps at nuclear power plants. Protecting the thyroid gland of infants and children remains a priority because of increased incidence of thyroid cancer in the young exposed to radioiodines (such as (131)I and (133)I). There is a lack of clinical studies for KI and radioiodines in children or infants to draw definitive conclusions about the effectiveness and safety of KI administration in the young. In this paper, we compare functional aspects of the hypothalamic-pituitary-thyroid (HPT) axis in the young and adults and review the limited studies of KI in children. The HPT axis in the infant and child is hyperactive and therefore will respond less effectively to KI treatment compared to adults. Research on the safety and efficacy of KI in infants and children is needed.
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Anti-angiogenesis therapy in the Vx2 rabbit cancer model with a lipase-cleavable Sn 2 taxane phospholipid prodrug using ?(v)??-targeted theranostic nanoparticles.
Theranostics
PUBLISHED: 01-01-2014
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In nanomedicine, the hydrophobic nature of paclitaxel has favored its incorporation into many nanoparticle formulations for anti-cancer chemotherapy. At lower doses taxanes are reported to elicit anti-angiogenic responses. In the present study, the facile synthesis, development and characterization of a new lipase-labile docetaxel prodrug is reported and shown to be an effective anti-angiogenic agent in vitro and in vivo. The Sn 2 phosphatidylcholine prodrug was stably incorporated into the lipid membrane of ?(v)??-integrin targeted perfluorocarbon (PFC) nanoparticles (?(v)??-Dxtl-PD NP) and did not appreciably release during dissolution against PBS buffer or plasma over three days. Overnight exposure of ?(v)??-Dxtl-PD NP to plasma spiked with phospholipase enzyme failed to liberate the taxane from the membrane until the nanoparticle integrity was compromised with alcohol. The bioactivity and efficacy of ?(v)??-Dxtl-PD NP in endothelial cell culture was as effective as Taxol(®) or free docetaxel in methanol at equimolar doses over 96 hours. The anti-angiogenesis effectiveness of ?(v)??-Dxtl-PD NP was demonstrated in the Vx2 rabbit model using MR imaging of angiogenesis with the same ?(v)??-PFC nanoparticle platform. Nontargeted Dxtl-PD NP had a similar MR anti-angiogenesis response as the integrin-targeted agent, but microscopically measured decreases in tumor cell proliferation and increased apoptosis were detected only for the targeted drug. Equivalent dosages of Abraxane(®) given over the same treatment schedule had no effect on angiogenesis when compared to control rabbits receiving saline only. These data demonstrate that ?(v)??-Dxtl-PD NP can reduce MR detectable angiogenesis and slow tumor progression in the Vx2 model, whereas equivalent systemic treatment with free taxane had no benefit.
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Crack orientation and depth estimation in a low-pressure turbine disc using a phased array ultrasonic transducer and an artificial neural network.
Sensors (Basel)
PUBLISHED: 07-16-2013
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Stress corrosion cracks (SCC) in low-pressure steam turbine discs are serious hidden dangers to production safety in the power plants, and knowing the orientation and depth of the initial cracks is essential for the evaluation of the crack growth rate, propagation direction and working life of the turbine disc. In this paper, a method based on phased array ultrasonic transducer and artificial neural network (ANN), is proposed to estimate both the depth and orientation of initial cracks in the turbine discs. Echo signals from cracks with different depths and orientations were collected by a phased array ultrasonic transducer, and the feature vectors were extracted by wavelet packet, fractal technology and peak amplitude methods. The radial basis function (RBF) neural network was investigated and used in this application. The final results demonstrated that the method presented was efficient in crack estimation tasks.
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Sensitive liquid chromatography/mass spectrometry methods for quantification of pomalidomide in mouse plasma and brain tissue.
J Pharm Biomed Anal
PUBLISHED: 05-27-2013
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Pomalidomide was recently approved by the United States Food and Drug Administration for the treatment of patients with relapsed or refractory multiple myeloma who have received at least two prior therapies. As pomalidomide is increasingly evaluated in other diseases and animal disease models, this paper presents development and validation of a sensitive liquid chromatography tandem mass spectrometry assay for quantification of pomalidomide in mouse plasma and brain tissue to fill a gap in published preclinical pharmacokinetic and analytical data with this agent. After acetonitrile protein precipitation, pomalidomide and internal standard, hesperitin, were separated with reverse phase chromatography on a C-18 column with a gradient mobile phase of water and acetonitrile with 0.1% fomic acid. Positive atmospheric pressure chemical ionization mass spectrometry with selected reaction monitoring mode was applied to achieve 0.3-3000nM (0.082-819.73ng/mL) linear range in mouse plasma and 0.6-6000pmol/g in brain tissue. The within- and between-batch accuracy and precision were less than 15% for both plasma and brain tissue. The method was applied to measure pomalidomide concentrations in plasma and brain tissue in a pilot mouse pharmacokinetic study with an intravenous dose of 0.5mg/kg. This assay can be applied for thorough characterization of pomalidomide pharmacokinetics and tissue distribution in mice.
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Biological response of high-back crucian carp (Carassius auratus) during different life stages to wastewater treatment plant effluent.
Environ Sci Pollut Res Int
PUBLISHED: 05-09-2013
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This study presents the adverse effects of endocrine disrupting chemicals (EDCs) in effluent of wastewater treatment plants (WwTPs) on fish health. A study of chronic exposure to WwTPs effluent for 10 months was undertaken in high-back crucian carp (Carassius auratus) during different life stages, covering early-life-stage (ELS), prespawning period, and postspawning period. Condition factor (CF), gonadosomatic index (GSI), hepatosomatic index (HSI), and plasma vitellogenin (VTG) levels were employed as indicators to assess biological effects of effluent on this gynogenesis species. Meanwhile, some high-back crucian carp were caged in Demonstration Base of Biological Purification for Filter-feeding Fish (hereinafter, Demonstration Base), as WwTPs effluent exposure controls. In the meantime, a depuration study was carried out to determine whether or not the estrogenic effects caused by effluent exposure could be reduced after moving fish into EDCs-free water. CF, HSI, GSI, and plasma Vtg levels of high-back crucian carp caged in Demonstration Base were generally in accordance with seasonal change. Effluent exposure inhibited gonadal growth, reducing GSI in ELS while increasing it around spawning, sharpened liver burdens, increasing HSI, and induced abnormal Vtg expression in juvenile high-back crucian carp, augmenting Vtg concentrations in plasma. Around spawning period, Vtg in high-back crucian carp were mainly induced by endogenous estrogens, and EDCs in effluent had less influence on them. Staying in EDCs-free water for 30 days made high-back crucian carp recover from effects of previous effluent exposure, relieving inhibition of gonadal development and hypertrophy of liver as well as reducing Vtg induced by EDCs in effluent. The results revealed that high-back crucian carp in ELS are more sensitive to WwTPs effluent exposure. Additionally, the depuration study showed a clearance of the estrogenic effects caused by effluent.
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Solubility properties and spectral investigation of dilute SO2 in a triethylene glycol + water + La3+ system.
J Phys Chem B
PUBLISHED: 04-30-2013
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Isothermal gas-liquid equilibrium (GLE) data were determined for dilute SO2 in a triethylene glycol (TEG) + water (W) system (TEGW) at 298.15 K and 123.15 kPa, in which SO2 partial pressures were calculated in the range 0-130 Pa. When La(3+) was added into TEGWs, GLE data suggested that adding of La(3+) ion markedly increased the solubility of dilute SO2. By fitting of these data, Henrys law constants (HLC) were obtained. For acquiring the important absorption mechanism, UV, FTIR, (1)H NMR, and fluorescence spectra in absorption processes of SO2 were investigated. On the basis of these spectral results, the possibility of intermolecular hydrogen bond formation by hydroxyl oxygen atoms in the TEG molecule with hydrogen atoms in the H2O molecule and S···O interaction formation by hydroxyl oxygen atoms in the TEG molecule with the sulfur atom in the SO2 molecule was discussed.
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Assessing intrarenal nonperfusion and vascular leakage in acute kidney injury with multinuclear (1) H/(19) F MRI and perfluorocarbon nanoparticles.
Magn Reson Med
PUBLISHED: 04-09-2013
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We sought to develop a unique sensor-reporter approach for functional kidney imaging that employs circulating perfluorocarbon nanoparticles and multinuclear (1) H/(19) F MRI.
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Prediction and evaluation of route dependent dosimetry of BPA in rats at different life stages using a physiologically based pharmacokinetic model.
Toxicol. Appl. Pharmacol.
PUBLISHED: 02-25-2013
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Bisphenol A (BPA) has received considerable attention throughout the last decade due to its widespread use in consumer products. For the first time a physiologically based pharmacokinetic (PBPK) model was developed in neonatal and adult rats to quantitatively evaluate age-dependent pharmacokinetics of BPA and its phase II metabolites. The PBPK model was calibrated in adult rats using studies on BPA metabolism and excretion in the liver and gastrointestinal tract, and pharmacokinetic data with BPA in adult rats. For immature rats the hepatic and gastrointestinal metabolism of BPA was inferred from studies on the maturation of phase II enzymes coupled with serum time course data in pups. The calibrated model predicted the measured serum concentrations of BPA and BPA conjugates after administration of 100?g/kg of d6-BPA in adult rats (oral gavage and intravenous administration) and postnatal days 3, 10, and 21 pups (oral gavage). The observed age-dependent BPA serum concentrations were partially attributed to the immature metabolic capacity of pups. A comparison of the dosimetry of BPA across immature rats and monkeys suggests that dose adjustments would be necessary to extrapolate toxicity studies from neonatal rats to infant humans.
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Facile synthesis of large-area ultrathin hexagonal BN films via self-limiting growth at the molten B?O? surface.
Small
PUBLISHED: 01-17-2013
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A self-limiting growth process based on the interface-controlled reaction of molten boron oxide (B2 O3 ) with ammonia (NH3 ) is demonstrated for the facile and lost-cost synthesis of ultrathin (20-30 nm) crystalline hexagonal boron nitride (h-BN) films over large areas. The as-grown h-BN films are of high quality, being densely continuous, uniform and smooth, and highly transparent over a broad wavelength range.
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Surface passivation of carbon nanoparticles with branched macromolecules influences near infrared bioimaging.
Theranostics
PUBLISHED: 01-01-2013
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A superior and commercially exploitable green synthesis of optically active carbon nanoparticle (OCN) is revealed in this work. The naked carbon particles (<20 nm) were derived from commercial food grade honey. The fluorescence properties of these particles were significantly enhanced by utilizing hyberbranched polymer for surface passivation. A dramatic increase in near infrared emission was achieved compared to a linear polymer (PEG) coated carbon nanoparticles. Interestingly, as passivating agent becomes more extensively branched (pseudo generation 2 to 4), the average radiant efficiency amplifies considerably as a direct result of the increasing surface area available for light passivation. The particles showed negligible loss of cell viability in presence of endothelial cells in vitro. Preliminary in vivo experiment showed high contrast enhancement in auxiliary lymphnode in a mouse model. The exceptionally rapid lymphatic transport of these particles suggests that such an approach may offer greater convenience and reduced procedural expense, as well as improved surgical advantage as the patient is positioned on the table for easier resection.
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6?-naltrexol, a peripherally selective opioid antagonist that inhibits morphine-induced slowing of gastrointestinal transit: an exploratory study.
Pain Med
PUBLISHED: 11-28-2011
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? Opioid-induced constipation is a frequent side effect of opioid pain therapy due to opioid effects on the enteric nervous system, including gastric emptying and fluid absorption. The current exploratory studies were conducted to determine whether the neutral opioid antagonist 6?-naltrexol, the primary metabolite of naltrexone, could selectively inhibit gastrointestinal opioid effects in human subjects.
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In-situ cadmium phytoremediation using Solanum nigrum L.: the bio-accumulation characteristics trail.
Int J Phytoremediation
PUBLISHED: 10-07-2011
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In this study, Solanum nigrum L. was used in-situ for Cdphytoremediation in Cd polluted soil on Shenyang Zhangshi Irrigation area (SZIA) in 2008. The performance of the plant over the whole growth stage was assessed. Results showed, during the whole experimental stage, the aboveground biomass of single Solanum nigrum L. grew by a factor of 190, from 1.6 +/- 0.4 g to 300.3 +/- 30.2 g with 141.2 times extracted Cd increase from 0.025 +/- 0.001 to 3.53 +/- 0.16 mg. Both the distribution of biomass and amount of extracted Cd in the above-ground part of the plant changed according to the growth of the plant. Particularly, the percentage of biomass and extracted Cd in the stem increased from 20% to 80% and from 11% to 69%, respectively. The bioconcentration factor and transfer factor both varied significantly during the growth of the plant and the lowest values were measured at the flowering stage (0.94 +/- 0.31 and 3.48 +/- 1.14 respectively). The results in this paper provide reference values for the future research on the application of Solanum nigrum L. in phytoremediation and on chemical or/and agricultural strategies for phytoextraction efficiency enhancement.
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Novel tricyclic inhibitors of IKK2: discovery and SAR leading to the identification of 2-methoxy-N-((6-(1-methyl-4-(methylamino)-1,6-dihydroimidazo[4,5-d]pyrrolo[2,3-b]pyridin-7-yl)pyridin-2-yl)methyl)acetamide (BMS-066).
Bioorg. Med. Chem. Lett.
PUBLISHED: 08-22-2011
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The synthesis, structure-activity relationships (SAR), and biological results of pyridyl-substituted azaindole based tricyclic inhibitors of IKK2 are described. Compound 4m demonstrated potent in vitro potency, acceptable pharmacokinetic and physicochemical properties, and efficacy when dosed orally in a mouse model of inflammatory bowel disease.
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Phase I trial of lenalidomide and CCI-779 in patients with relapsed multiple myeloma: evidence for lenalidomide-CCI-779 interaction via P-glycoprotein.
J. Clin. Oncol.
PUBLISHED: 08-08-2011
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Multiple myeloma (MM) is an incurable plasma-cell neoplasm for which most treatments involve a therapeutic agent combined with dexamethasone. The preclinical combination of lenalidomide with the mTOR inhibitor CCI-779 has displayed synergy in vitro and represents a novel combination in MM.
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Wet-chemistry-assisted nanotube-substitution reaction for high-efficiency and bulk-quantity synthesis of boron- and nitrogen-codoped single-walled carbon nanotubes.
J. Am. Chem. Soc.
PUBLISHED: 08-08-2011
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We present an innovative wet-chemistry-assisted nanotube-substitution reaction approach for the highly efficient synthesis of boron- and nitrogen-codoped single-walled carbon nanotubes (B(x)C(y)N(z)-SWNTs) in bulk quantities. The as-synthesized ternary system B(x)C(y)N(z)-SWNTs are of high purity and quality and have fairly homogeneous B and N dopant concentrations. Electrical transport measurements on SWNT-network thin-film transistors revealed that the B(x)C(y)N(z)-SWNTs were composed primarily of the semiconducting nanotubes, in contrast to the starting pristine C-SWNTs, which consisted of a heterogeneous mixture of both semiconducting and metallic types.
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[Changes of certain oxidative, anti-oxidative and vascular function indexes of New Zealand rabbit exposed by high-fluoride].
Wei Sheng Yan Jiu
PUBLISHED: 11-10-2010
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To observe certain changes of oxidation, anti-oxidation and vascular function indexes of Application of New Zealand rabbit exposed by high-fluoride.
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Dose escalation of lenalidomide in relapsed or refractory acute leukemias.
J. Clin. Oncol.
PUBLISHED: 10-18-2010
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Lenalidomide is effective in myeloma and low-risk myelodysplastic syndromes with deletion 5q. We report results of a phase I dose-escalation trial of lenalidomide in relapsed or refractory acute leukemia.
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Small molecule antagonist of leukocyte function associated antigen-1 (LFA-1): structure-activity relationships leading to the identification of 6-((5S,9R)-9-(4-cyanophenyl)-3-(3,5-dichlorophenyl)-1-methyl-2,4-dioxo-1,3,7-triazaspiro[4.4]nonan-7-yl)nicotin
J. Med. Chem.
PUBLISHED: 04-22-2010
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Leukocyte function-associated antigen-1 (LFA-1), also known as CD11a/CD18 or alpha(L)beta(2), belongs to the beta(2) integrin subfamily and is constitutively expressed on all leukocytes. The major ligands of LFA-1 include three intercellular adhesion molecules 1, 2, and 3 (ICAM 1, 2, and 3). The interactions between LFA-1 and the ICAMs are critical for cell adhesion, and preclinical animal studies and clinical data from the humanized anti-LFA-1 antibody efalizumab have provided proof-of-concept for LFA-1 as an immunological target. This article will detail the structure-activity relationships (SAR) leading to a novel second generation series of highly potent spirocyclic hydantoin antagonists of LFA-1. With significantly enhanced in vitro and ex vivo potency relative to our first clinical compound (1), as well as demonstrated in vivo activity and an acceptable pharmacokinetic and safety profile, 6-((5S,9R)-9-(4-cyanophenyl)-3-(3,5-dichlorophenyl)-1-methyl-2,4-dioxo-1,3,7-triazaspiro-[4.4]nonan-7-yl)nicotinic acid (2e) was selected to advance into clinical trials.
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Deregulation of growth factor, circadian clock, and cell cycle signaling in regenerating hepatocyte RXRalpha-deficient mouse livers.
Am. J. Pathol.
PUBLISHED: 12-24-2009
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Activation of the nuclear receptors constitutive androstane receptor, pregnane X receptor, and peroxisome proliferator-activated receptor alpha results in hepatomegaly, and these nuclear receptors are implicated in the regulation of liver regeneration. Retinoid X receptor (RXR)alpha is an essential partner of these nuclear receptors. Therefore, we studied the role of hepatocyte RXRalpha in liver regeneration using partial hepatectomy model. The results showed that hepatocyte RXRalpha deficiency caused an approximately 20-hour delay in hepatocyte proliferation after partial hepatectomy. Several pathways, including growth factors and the circadian cell cycle, were impaired due to hepatocyte RXRalpha deficiency. In addition, the expression patterns of hepatocyte growth factor, fibroblast growth factor 2, platelet-derived growth factor, and transforming growth factor alpha were altered due to lack of RXRalpha. Furthermore, the peroxisome proliferator-activated receptor alpha/brain and muscle Arnt-like protein 1/Rev-erbalpha/P21 pathway was compromised, and Cry1/Cry2 and Wee1/Per1 expression was deregulated in regenerating RXRalpha-null livers. Accordingly, the expression and regulation of cyclin D1/Cyclin- dependent Kinase (Cdk)4, cyclin E1/Cdk2, cyclin A2/Cdk2, and cyclin B1/Cdk1 after partial hepatectomy were altered in regenerating RXRalpha-null livers. Hepatocyte RXRalpha deficiency also affected the basal, as well as regeneration-induced cyclin E1 expression levels. Activation of RXRalpha by retinoic acids increased the cyclin E1 promoter activity indicating retinoic acid-mediated signaling positively controls cyclin E1 gene expression. As many of these observed changes were not documented in the regenerating livers of other nuclear receptor knockout mice, these observed effects may be hepatocyte RXRalpha specific.
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Methane emission by plant communities in an alpine meadow on the Qinghai-Tibetan Plateau: a new experimental study of alpine meadows and oat pasture.
Biol. Lett.
PUBLISHED: 05-01-2009
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Recently, plant-derived methane (CH(4)) emission has been questioned because limited evidence of the chemical mechanism has been identified to account for the process. We conducted an experiment with four treatments (i.e. winter-grazed, natural alpine meadow; naturally restored alpine meadow eight years after cultivation; oat pasture and bare soil without roots) during the growing seasons of 2007 and 2008 to examine the question of CH(4) emission by plant communities in the alpine meadow. Each treatment consumed CH(4) in closed, opaque chambers in the field, but two types of alpine meadow vegetation reduced CH(4) consumption compared with bare soil, whereas oat pasture increased consumption. This result could imply that meadow vegetation produces CH(4). However, measurements of soil temperature and water content showed significant differences between vegetated and bare soil and appeared to explain differences in CH(4) production between treatments. Our study strongly suggests that the apparent CH(4) production by vegetation, when compared with bare soil in some previous studies, might represent differences in soil temperature and water-filled pore space and not the true vegetation sources of CH(4).
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Synthesis, initial SAR and biological evaluation of 1,6-dihydroimidazo[4,5-d]pyrrolo[2,3-b]pyridin-4-amine derived inhibitors of IkappaB kinase.
Bioorg. Med. Chem. Lett.
PUBLISHED: 03-09-2009
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A new series of tricyclic-based inhibitors of IKK have been derived from an earlier lead compound. The synthesis and structure-activity relationships (SAR) are described. Compound 4k inhibited TNF production in rats stimulated with LPS.
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Gender disparity of hepatic lipid homoeostasis regulated by the circadian clock.
J. Biochem.
PUBLISHED: 01-27-2009
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The mammalian clock regulates major aspects of energy metabolism, including glucose and lipid homoeostasis as well as mitochondrial oxidative metabolism. This study is to identify specific patterns of circadian rhythms for lipid homoeostasis in both female and male mouse livers, and to clarify gender disparity in coupling the peripheral circadian clock to lipid metabolic outputs by nuclear receptors. To achieve this, profiling the diurnal hepatic expression of genes encoding circadian clocks, nuclear receptors and lipid metabolic enzymes was performed. Hepatic lipid levels including cholesterol, triglyceride and non-esterified fatty acids (NEFAs) were monitored over a 24-h period. The cosinor analysis revealed that several genes encoding nuclear receptors and enzymes involved in the lipid metabolic pathway were rhythmically expressed in liver in phase with the peripheral clocks, which were correlated with the diurnal changes of hepatic lipid levels. Gender disparity was observed for circadian characteristics including mesor and amplitude values, accompanied with advances in acrophases in female mouse livers. Accordingly, gender differences were also observed in diurnal lipid homoeostasis. The identification of cycling patterns for lipid metabolic pathways in both female and male mouse livers may shed light on the development of gender-based treatment for human diseases related to the coordination of the cellular clock and control of lipid homoeostasis.
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Renal vascular inflammation induced by Western diet in ApoE-null mice quantified by (19)F NMR of VCAM-1 targeted nanobeacons.
Nanomedicine
PUBLISHED: 01-19-2009
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We have designed multifunctional nanoparticulate reporter bioprobes capable of targeting vascular cell adhesion molecule 1 (VCAM-1), which is up-regulated in numerous inflammatory processes. These perfluorocarbon-cored nanoparticles emit a unique (19)F magnetic resonance (MR) signature, providing the potential to localize and quantify VCAM-1 expression in early atherosclerosis. Nanoparticle-VCAM-1 targeting specificity was confirmed by in vitro binding and competition studies. ApoE-null and control C57-BL6 mice (n = 6/group), fed a Western diet for 35 weeks, were injected i.v. with targeted or non-targeted nanoparticles. After two hours, kidneys were excised and prepared for analysis. ApoE-null kidneys exhibited increased VCAM-1-targeted nanoparticle content over healthy controls by (19)F MR spectroscopy (36.5+8.8 vs. 9.3+2.2 x 10(8)/g, P < .05), which correlated with increased VCAM-1 staining (2.5 +/- 1.3% vs. 0.9 +/- 0.3%, P < .05); their relative biodistributions were confirmed by fluorescence microscopy and MR imaging. These molecular imaging agents offer new approaches for detection, quantification, and longitudinal evaluation of early inflammation utilising (19)F MR spectroscopy and imaging.
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Total synthesis of (-)-5,6-dihydrocineromycin B.
J. Org. Chem.
PUBLISHED: 01-01-2009
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An asymmetric total synthesis of (-)-5,6-dihydrocineromycin B has been accomplished in 13 steps from (-)-linalool O-triethylsilyl ether or 12 steps from geraniol. The present synthesis features (i) an intermolecular Wittig reaction involving an aldehyde possessing a ketophosphonate functionality and (ii) an intramolecular Horner-Wadsworth-Emmons olefination.
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Evaluation of EROD and CYP3A4 activities in earthworm Eisenia fetida as biomarkers for soil heavy metal contamination.
J. Hazard. Mater.
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In this study, the effects of heavy metals (Cd, Cu, Pb, Zn) on EROD and CYP3A4 activities in the earthworm Eisenia fetida were evaluated to find out their possible induction and potential as biomarkers for soil heavy metal contamination. The earthworms were exposed to increasing concentrations of Cd (0.1-8 mg L(-1)), Cu (10-200 mg L(-1)), Pb (20-400 mg L(-1)) or Zn (50-400 mg L(-1)) in filter papers for 48 h. EROD activity was significantly changed in dose-dependent manners after exposure to each of the four metals. CYP3A4 activity was significantly induced by Cd and Pb, rather by Cu and Zn. This is the ?rst report on heavy metal-induced changes of CYP3A4 activity in earthworms. Among the four heavy metals, Cd was the most potent inducing EROD and CYP3A4. While EROD and CYP3A4 activities showed a similar trend, EROD is more sensitive than CYP3A4 activity in E. fetida as a biomarker for heavy metals pollution.
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Enzymatic biomarkers of earthworms Eisenia fetida in response to individual and combined cadmium and pyrene.
Ecotoxicol. Environ. Saf.
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The responses of enzymatic biomarkers of earthworms Eisenia fetida to low-level exposures of cadmium (Cd) (2.50mg kg(-1)), pyrene (0.96mg kg(-1)) or their combination were investigated in this study. A set of enzymatic biomarkers, namely, cytochrome P450 (CYP) as a family of phase I enzymes, glutathione-s-transferase (GST) as one of phase II enzymes and antioxidant enzymes (superoxide dismutase (SOD) and catalase (CAT) ), was selected to evaluate the responses of the earthworms in a period upto eight weeks. The earthworms exposed to the mixture of Cd and pyrene demonstrated different responses of the enzymatic biomarkers from those exposed to Cd or pyrene alone. The responses of enzymatic biomarkers to the combined exposure were time-dependent, with initial antagonistic effects on CYP content and activities of GST and SOD, but with additive effects at the end of experiment causing the reductions of CYP content and GST activity and the enhancement of activities of SOD and CAT. Our results indicated the toxicity of low-level pyrene may be prolonged by the co-presence of Cd.
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Biochemical responses of earthworm Eisenia fetida exposed to cadmium-contaminated soil with long duration.
Bull Environ Contam Toxicol
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The biochemical responses of the earthworms, Eisenia fetida, exposed to a series of Cd concentrations (0.00, 1.25, 2.50, 5.00 and 10.00 mg Cd(2+) kg(-1) soil) for up to 8 weeks were investigated, aiming to evaluate the sublethal effects of Cd with long exposure and to explore the potential for applying these responses as biomarkers to indicate the Cd-contaminated soil. The following biochemical parameters were determined: cytochrome P450 (CYP) contents and activities of superoxide dismutase (SOD), catalase (CAT) and glutathione-s-transferase (GST). Cadmium concentrations in all earthworms were apparently accumulated in 4 weeks, and showed minor changes in weeks 6-8 compared to the first 4 weeks. CYP presented a significant elevation in 2-4 weeks and a decline in 6-8 weeks in each treated group. The activities of SOD and CAT showed an obvious increase with exposure of 6-8 weeks while their levels were not affected in 4 weeks in each treated group. GST activity revealed significant activation starting from week 4. This study confirmed the significance of applying a suite of biomarkers rather than a selective choice to assess the impact of pollutants on organisms. It also indicated that the observed effects were more dependent upon exposure duration than dose.
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A multivalent three-point linkage analysis model of autotetraploids.
Brief. Bioinformatics
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Because of its widespread occurrence and role in shaping evolutionary processes in the biological kingdom, especially in plants, polyploidy has been increasingly studied from cytological to molecular levels. By inferring gene order, gene distances and gene homology, linkage mapping with molecular markers has proven powerful for investigating genome structure and organization. Here we review and assess a general statistical model for three-point linkage analysis in autotetraploids by integrating double reduction, a phenomenon that commonly occurs in autopolyploids whose chromosomes are derived from a single ancestral species. This model does not require any assumption on the distribution of the occurrence of double reduction and can handle the complexity of multilocus linkage in terms of crossover interference. Implemented with the expectation-maximization (EM) algorithms, the model can estimate and test the recombination fractions between less informative dominant markers, thus facilitating its practical implications for any autopolyploids in most of which inexpensive dominant markers are still used for their genetic and evolutionary studies. The model was applied to reanalyze a published data in tetraploid switchgrass, validating its practical usefulness and utilization.
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Pharmacokinetics and tissue disposition of lenalidomide in mice.
AAPS J
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Lenalidomide is a synthetic derivative of thalidomide exhibiting multiple immunomodulatory activities beneficial in the treatment of several hematological malignancies. Murine pharmacokinetic characterization necessary for translational and further preclinical investigations has not been published. Studies herein define mouse plasma pharmacokinetics and tissue distribution after intravenous (IV) bolus administration and bioavailability after oral and intraperitoneal delivery. Range finding studies used lenalidomide concentrations up to 15 mg/kg IV, 22.5 mg/kg intraperitoneal injections (IP), and 45 mg/kg oral gavage (PO). Pharmacokinetic studies evaluated doses of 0.5, 1.5, 5, and 10 mg/kg IV and 0.5 and 10 mg/kg doses for IP and oral routes. Liquid chromatography-tandem mass spectrometry was used to quantify lenalidomide in plasma, brain, lung, liver, heart, kidney, spleen, and muscle. Pharmacokinetic parameters were estimated using noncompartmental and compartmental methods. Doses of 15 mg/kg IV, 22.5 mg/kg IP, and 45 mg/kg PO lenalidomide caused no observable toxicity up to 24 h postdose. We observed dose-dependent kinetics over the evaluated dosing range. Administration of 0.5 and 10 mg/kg resulted in systemic bioavailability ranges of 90-105% and 60-75% via IP and oral routes, respectively. Lenalidomide was detectable in the brain only after IV dosing of 5 and 10 mg/kg. Dose-dependent distribution was also observed in some tissues. High oral bioavailability of lenalidomide in mice is consistent with oral bioavailability in humans. Atypical lenalidomide tissue distribution was observed in spleen and brain. The observed dose-dependent pharmacokinetics should be taken into consideration in translational and preclinical mouse studies.
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Rapid quantification of oxygen tension in blood flow with a fluorine nanoparticle reporter and a novel blood flow-enhanced-saturation-recovery sequence.
Magn Reson Med
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We present a novel blood flow-enhanced-saturation-recovery (BESR) sequence, which allows rapid in vivo T1 measurement of blood for both (1)H and (19)F nuclei. BESR sequence is achieved by combining homogeneous spin preparation and time-of-flight image acquisition and therefore preserves high time efficiency and signal-to-noise ratio for (19)F imaging of circulating perfluorocarbon nanoparticles comprising a perfluoro-15-crown-5-ether core and a lipid monolayer (nominal size = 250 nm). The consistency and accuracy of the BESR sequence for measuring T1 of blood was validated experimentally. With a confirmed linear response feature of (19)F R1 with oxygen tension in both salt solution and blood sample, we demonstrated the feasibility of the BESR sequence to quantitatively determine the oxygen tension within mouse left and right ventricles under both normoxia and hyperoxia conditions. Thus, (19)F BESR MRI of circulating perfluorocarbon nanoparticles represents a new approach to noninvasively evaluate intravascular oxygen tension.
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Antiangiogenic nanotherapy with lipase-labile Sn-2 fumagillin prodrug.
Nanomedicine (Lond)
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The chemical instability of antiangiogenic fumagillin, combined with its poor retention during intravascular transit, requires an innovative solution for clinical translation. We hypothesized that an Sn-2 lipase-labile fumagillin prodrug, in combination with a contact-facilitated drug delivery mechanism, could be used to address these problems.
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Absorption and disposition of bromate in F344 rats.
Toxicology
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Bromate (BrO(3)(-)) is a ubiquitous by-product of using ozone to disinfect water containing bromide (Br(-)). The reactivity of BrO(3)(-) with biological reductants suggests that its systemic absorption and distribution to target tissues may display non-linear behavior as doses increase. The intent of this study is to determine the extent to which BrO(3)(-) is systemically bioavailable via oral exposure and broadly identify its pathways of degradation. In vitro experiments of BrO(3)(-) degradation in rat blood indicate a rapid initial degradation immediately upon addition that is >98% complete at concentrations up to 66?M in blood. As initial concentrations are increased, progressively lower fractions are lost prior to the first measurement. Secondary to this initial loss, a slower and predictable first order degradation rate was observed (10%/min). Losses during both phases were accompanied by increases in Br(-) concentrations indicating that the loss of BrO(3)(-) was due to its reduction. In vivo experiments were conducted using doses of BrO(3)(-) ranging from 0.077 to 15.3mg/kg, administered intravenously (IV) or orally (gavage) to female F344 rats. The variable nature and uncertain source of background concentrations of BrO(3)(-) limited derivation of terminal half-lives, but the initial half-life was approximately 10min for all dose groups. The area under the curve (AUC) and peak concentrations (C(t=5)) were linearly related to IV dose up to 0.77mg/kg; however, disproportionate increases in the AUC and C(t=5) and a large decrease in the volume of distribution was observed when IV doses of 1.9 and 3.8mg/kg were administered. The average terminal half-life of BrO(3)(-) from oral administration was 37min, but this was influenced by background levels of BrO(3)(-) at lower doses. With oral doses, the AUC and C(max) increased linearly with dose up to 15.3mgBrO(3)(-)/kg. BrO(3)(-) appeared to be 19-25% bioavailable without an obvious dose-dependency between 0.077 and 1.9mg/kg. The urinary elimination of BrO(3)(-) and Br(-) was measured from female F344 rats for four days following administration of single doses of 8.1mgKBrO(3)/kg and for 15 days after a single dose of 5.0mgKBr/kg. BrO(3)(-) elimination was detected over the first 12h, but Br(-) elimination from BrO(3)(-) over the first 48h was 18% lower than expected based on that eliminated from an equimolar dose of Br(-) (15.5±1.6 vs. 18.8±1.2?mol/kg, respectively). The cumulative excretion of Br(-) from KBr vs. KBrO(3) was equivalent 72h after administration. The recovery of unchanged administered BrO(3)(-) in the urine ranged between 6.0 and 11.3% (creatinine corrected) on the 27th day of treatment with concentrations of KBrO(3) of 15, 60, and 400mg/L of drinking water. The recovery of total urinary bromine as Br(-)+BrO(3)(-) ranged between 61 and 88%. An increase in the fraction of the daily BrO(3)(-) dose recovered in the urine was observed at the high dose to both sexes. The deficit in total bromine recovery raises the possibility that some brominated biochemicals may be produced in vivo and more slowly metabolized and eliminated. This was supported by measurements of dose-dependent increases of total organic bromine (TOBr) that was eliminated in the urine. The role these organic by-products play in BrO(3)(-)-induced cancer remains to be established.
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A unifying framework for bivalent multilocus linkage analysis of allotetraploids.
Brief. Bioinformatics
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An allotetraploid has four paired sets of chromosomes derived from different diploid species, whose meiotic behavior is qualitatively different from the underlying diploids. According to a traditional view, meiotic pairing occurs only between homologous chromosomes, but new evidence indicates that homoeologous chromosomes may also pair to a lesser extent compared with homolog pairing. Here, we describe and assess a unifying analytical framework that incorporates differential chromosomal pairing into a multilocus linkage model. The preferential pairing factor is used to quantify the probability difference of pairing occurring between homologous chromosomes and homoeologous chromosomes. The unifying framework allows simultaneous estimation of the linkage, genetic interference and preferential pairing factor using commonly existing multiplex markers. We compared the unifying approach and traditional approaches assuming random chromosomal pairing by analyzing marker data collected in a full-sib family of tetraploid switchgrass, a bioenergy species whose diploid origins are undefined, but with subgenomes that are genetically well differentiated. The unifying framework provides a better tool for estimating the meiotic linkage and constructing a genetic map for allotetraploids.
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The Rix1 (Ipi1p-2p-3p) complex is a critical determinant of DNA replication licensing independent of their roles in ribosome biogenesis.
Cell Cycle
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Several replication-initiation proteins are assembled stepwise onto replicators to form pre-replicative complexes (pre-RCs) to license eukaryotic DNA replication. We performed a yeast functional proteomic screen and identified the Rix1 complex members (Ipi1p-Ipi2p/Rix1-Ipi3p) as pre-RC components and critical determinants of replication licensing and replication-initiation frequency. Ipi3p interacts with pre-RC proteins, binds chromatin predominantly at ARS sequences in a cell cycle-regulated and ORC- and Noc3p-dependent manner and is required for loading Cdc6p, Cdt1p and MCM onto chromatin to form pre-RC during the M-to-G? transition and for pre-RC maintenance in G? phase-independent of its role in ribosome biogenesis. Moreover, Ipi1p and Ipi2p, but not other ribosome biogenesis proteins Rea1p and Utp1p, are also required for pre-RC formation and maintenance, and Ipi1p, -2p and -3p are interdependent for their chromatin association and function in pre-RC formation. These results establish a new framework for the hierarchy of pre-RC proteins, where the Ipi1p-2p-3p complex provides a critical link between ORC-Noc3p and Cdc6p-Cdt1p-MCM in replication licensing.
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