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Find video protocols related to scientific articles indexed in Pubmed.
Ghrelin receptor regulates appetite and satiety during aging in mice by regulating meal frequency and portion size but not total food intake.
J. Nutr.
PUBLISHED: 07-02-2014
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Aging is often associated with overweight and obesity. There exists a long-standing debate about whether meal pattern also contributes to the development of obesity. The orexigenic hormone ghrelin regulates appetite and satiety by activating its receptor, growth hormone secretagogue receptor (GHS-R). In mice, circulating ghrelin concentrations and brain GHS-R expression were shown to increase with aging. To assess whether GHS-R regulates feeding pattern during aging, we studied meal patterns for the following cohorts of male mice fed a normal unpurified diet: 1) 3-4 mo, young wild-type (WT) mice; 2) 3-4 mo, young Ghsr-null (Ghsr(-/-)) mice; 3) 12-14 mo, middle-aged WT (WT-M) mice; 4) 12-14 mo, middle-aged Ghsr(-/-) (Ghsr(-/-)-M) mice; 5) 24-26 mo, old WT (WT-O) mice; and 6) 24-26 mo, old Ghsr(-/-) (Ghsr(-/-)-O) mice. Although the total daily food intake of Ghsr(-/-) mice was similar to that of WT controls, Ghsr(-/-)-M and Ghsr(-/-)-O mice had 9% (P = 0.07) and 16% (P < 0.05) less body weight compared with WT-M and WT-O mice, respectively, primarily due to reduced fat mass (P < 0.05, WT-M vs. Ghsr(-/-)-M and WT-O vs. Ghsr(-/-)-O). Intriguingly, Ghsr(-/-)-M mice ate larger meals (on average, Ghsr(-/-)-M mice ate 0.117 g/meal and WT-M mice ate 0.080 g/meal; P < 0.01) and took a longer time to eat (Ghsr(-/-)-M, 196.0 s and WT-M, 128.9 s; P < 0.01), but ate less frequently (Ghsr(-/-)-M, 31.0 times/d and WT-M, 42.3 times/d; P < 0.05) than WT-M controls. In addition, we found that expression of hypothalamic orexigenic peptides, neuropeptide Y (NPY) and agouti-related peptide (AgRP), was relatively lower in aged WT mice (P = 0.09 for NPY and P = 0.06 for AgRP), but anorexic peptide pro-opiomelanocortin (POMC) expression remained unchanged between the WT age groups. Interestingly, old Ghsr(-/-) mice had greater hypothalamic NPY expression (102% higher; P < 0.05) and AgRP expression (P = 0.07) but significantly lower POMC expression (P < 0.05) when compared with age-matched WT-O controls. Thus, our results indicate that GHS-R plays an important role in the regulation of meal pattern and that GHS-R ablation may modulate feeding behavior through the regulation of hypothalamic neuropeptides. Our results collectively suggest that ghrelin receptor antagonism may have a beneficial effect on metabolism during aging.
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Role of autophagy and apoptosis in wound tissue of deep second-degree burn in rats.
Acad Emerg Med
PUBLISHED: 04-16-2014
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The pathogenesis of burn wound progression is poorly understood. Contributing factors include continuous loss of blood perfusion, excessive inflammation, and elevated apoptosis levels in wound tissue. Macroautophagy (here referred to simply as "autophagy") is associated with many chronic diseases. The authors hypothesized that autophagy is involved in burn wound progression in a rat model of deep second-degree burn.
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OsABCB14 functions in auxin transport and iron homeostasis in rice (Oryza sativa L.).
Plant J.
PUBLISHED: 03-15-2014
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Members of the ATP Binding Cassette B/Multidrug-Resistance/P-glyco-protein (ABCB/MDR/PGP) subfamily were shown to function primarily in Oryza sativa (rice) auxin transport; however, none of the rice ABCB transporters have been functionally characterized. Here, we describe that a knock-down of OsABCB14 confers decreased auxin concentrations and polar auxin transport rates, conferring insensitivity to 2,4-dichlorophenoxyacetic acid (2,4-D) and indole-3-acetic acid (IAA). OsABCB14 displays enhanced specific auxin influx activity in yeast and protoplasts prepared from rice knock-down alleles. OsABCB14 is localized at the plasma membrane, pointing to an important directionality under physiological conditions. osabcb14 mutants were surprisingly found to be insensitive to iron deficiency treatment (-Fe). Their Fe concentration is higher and upregulation of Fe deficiency-responsive genes is lower in osabcb14 mutants than in wild-type rice (Nipponbare, NIP). Taken together, our results strongly support the role of OsABCB14 as an auxin influx transporter involved in Fe homeostasis. The functional characterization of OsABCB14 provides insights in monocot auxin transport and its relationship to Fe nutrition.
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Stability and encapsulation efficiency of sulforaphane microencapsulated by spray drying.
Carbohydr Polym
PUBLISHED: 02-11-2014
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Sulforaphane (SF) has received much attention because of its anticarcinogenic, antioxidant and anti-inflammatory properties, but it is quite unstable. Microencapsulation is one way to improve its stability. The aim of this work was to produce microcapsules containing sulforaphane using a spray drying technique. The effects of different wall materials, inlet air temperature and core to wall ratio on the SF stability, encapsulation efficiency, encapsulation yield, moisture content and SF content were determined. The results indicated that optimal encapsulation conditions for SF were: maltodextrin for the wall material, 170 °C for the inlet air temperature and 1:20 for the core/wall ratio. Characterization study showed that the microcapsules had a regular spherical shape. The stability of SF in spray dried microcapsules was greatly enhanced compared with that of free SF.
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Arbuscular mycorrhizal fungal phylogenetic groups differ in affecting host plants along heavy metal levels.
J Environ Sci (China)
PUBLISHED: 01-22-2014
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Arbuscular mycorrhizal fungi (AMF) are important components of soil microbial communities, and play important role in plant growth. However, the effects of AMF phylogenetic groups (Glomeraceae and non-Glomeraceae) on host plant under various heavy metal levels are not clear. Here we conducted a meta-analysis to compare symbiotic relationship between AMF phylogenetic groups (Glomeraceae and non-Glomeraceae) and host plant functional groups (herbs vs. trees, and non-legumes vs. legumes) at three heavy metal levels. In the meta-analysis, we calculate the effect size (ln(RR)) by taking the natural logarithm of the response ratio of inoculated to non-inoculated shoot biomass from each study. We found that the effect size of Glomeraceae increased, but the effect size of non-Glomeraceae decreased under high level of heavy metal compared to low level. According to the effect size, both Glomeraceae and non-Glomeraceae promoted host plant growth, but had different effects under various heavy metal levels. Glomeraceae provided more benefit to host plants than non-Glomeraceae did under heavy metal condition, while non-Glomeraceae provided more benefit to host plants than Glomeraceae did under no heavy metal. AMF phylogenetic groups also differed in promoting plant functional groups under various heavy metal levels. Interacting with Glomeraceae, herbs and legumes grew better than trees and non-legumes did under high heavy metal level, while trees and legumes grew better than herbs and non-legumes did under medium heavy metal level. Interacting with non-Glomeraceae, herbs and legumes grew better than trees and non-legumes did under no heavy metal. We suggested that the combination of legume with Glomeraceae could be a useful way in the remediation of heavy metal polluted environment.
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Regulation of skeletal muscle oxidative capacity and muscle mass by SIRT3.
PLoS ONE
PUBLISHED: 01-01-2014
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We have previously reported that the expression of mitochondrial deacetylase SIRT3 is high in the slow oxidative muscle and that the expression of muscle SIRT3 level is increased by dietary restriction or exercise training. To explore the function of SIRT3 in skeletal muscle, we report here the establishment of a transgenic mouse model with muscle-specific expression of the murine SIRT3 short isoform (SIRT3M3). Calorimetry study revealed that the transgenic mice had increased energy expenditure and lower respiratory exchange rate (RER), indicating a shift towards lipid oxidation for fuel usage, compared to control mice. The transgenic mice exhibited better exercise performance on treadmills, running 45% further than control animals. Moreover, the transgenic mice displayed higher proportion of slow oxidative muscle fibers, with increased muscle AMPK activation and PPAR? expression, both of which are known regulators promoting type I muscle fiber specification. Surprisingly, transgenic expression of SIRT3M3 reduced muscle mass up to 30%, likely through an up-regulation of FOXO1 transcription factor and its downstream atrophy gene MuRF-1. In summary, these results suggest that SIRT3 regulates the formation of oxidative muscle fiber, improves muscle metabolic function, and reduces muscle mass, changes that mimic the effects of caloric restriction.
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Intra-arterial chemotherapy is not superior to intravenous chemotherapy for malignant gliomas: a systematic review and meta-analysis.
Eur. Neurol.
PUBLISHED: 07-17-2013
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The efficacy and safety of intra-arterial (IA) chemotherapy versus intravenous (IV) chemotherapy for malignant gliomas were studied. We searched eight electronic databases to identify relevant randomized controlled trials that compared IA chemotherapy with IV chemotherapy in patients with malignant gliomas. This study was conducted in compliance with the Quality of Reporting of Meta-analysis (QUORUM) guidelines. The quality of data was assessed using the Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) approach. Four eligible randomized controlled trials including 460 patients were retrieved. Comparing IA chemotherapy and IV chemotherapy for malignant gliomas, disease control rate, efficacy rate, 1-year, 2-year, and 3-year overall survival as well as grade 3/4 leukocytopenia, thrombocytopenia, and anemia were not statistically different. In conclusion, IA chemotherapy is not superior to IV chemotherapy in terms of efficacy and overall survival as a treatment for malignant gliomas.
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Rapamycin reduces burn wound progression by enhancing autophagy in deep second-degree burn in rats.
Wound Repair Regen
PUBLISHED: 06-25-2013
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Burn wound progression is caused by many mechanisms including local tissue hypoperfusion, prolonged inflammation, free radical damage, apoptosis, and necrosis in burn wounds. Autophagy, a homeostatic process by which cells break down their own components, was found to protect against ischemic injury, inflammatory diseases, and apoptosis in some cases. We tested whether rapamycin, an autophagy inducer, could ameliorate burn wound progression and promote wound healing through autophagy enhancement. Using a previously described deep second-degree burn model, we first tested the effects of rapamycin on autophagic response in burn wound tissue. Autophagy levels in wound tissue of treated rats were increased as compared with controls. Furthermore, we found that laser Doppler flowmetry values and Na/K-ATPase activities were markedly higher in the treated wounds. The content of interleukin-8, methane dicarboxylic aldehyde, and myeloperoxidase activity in the wounds of treated rats were much lower than in controls. The apoptotic rates in treated wounds were much lower than controls as determined by terminal deoxynucleotidyl transferase mediated nick end labeling assay. Finally, histomorphological analysis showed that burn wound progression in the treatment group was ameliorated. The time to wound reepithelialization was shorter in the treated wounds than controls 22.5?±?1.4 days vs. 24.8?±?1.3 days (mean?±?standard deviation, p?
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Effects of curcumin on glucose metabolism in the brains of rats subjected to chronic unpredictable stress: a 18 F-FDG micro-PET study.
BMC Complement Altern Med
PUBLISHED: 05-01-2013
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Chronic unpredictable stress (CUS) can cause behavioral and physiological abnormalities that are important to the prediction of symptoms of depression that may be associated with cerebral glucose metabolic abnormalities. Curcumin showed potential antidepressant effects, but whether or not it can reverse cerebral functional abnormalities and so ameliorate depression remains unknown.
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Optimization of ultrasonic-assisted preparation of dietary fiber from corn pericarp using response surface methodology.
J. Sci. Food Agric.
PUBLISHED: 01-31-2013
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Corn pericarp, which is an industrial waste of corn starch production, is an important source of dietary fiber in cereals, with claimed health benefits. However, they used to be discarded or utilized as animal feed. The application of pre-ultrasound treatment is critical for achieving rapid preparation of desired components from plant materials and for preserving structural and molecular properties of these compounds. Ultrasonic-assisted preparation was used to produce dietary fiber from corn pericarp using response surface methodology.
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Effect of Poloxamer 188 on deepening of deep second-degree burn wounds in the early stage.
Burns
PUBLISHED: 11-12-2011
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To discuss the effect of Poloxamer 188 (P188) on deepening of deep second-degree burn wounds in the early stage after burn.
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Ablation of ghrelin receptor reduces adiposity and improves insulin sensitivity during aging by regulating fat metabolism in white and brown adipose tissues.
Aging Cell
PUBLISHED: 10-12-2011
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Aging is associated with increased adiposity in white adipose tissues and impaired thermogenesis in brown adipose tissues; both contribute to increased incidences of obesity and type 2 diabetes. Ghrelin is the only known circulating orexigenic hormone that promotes adiposity. In this study, we show that ablation of the ghrelin receptor (growth hormone secretagogue receptor, GHS-R) improves insulin sensitivity during aging. Compared to wild-type (WT) mice, old Ghsr(-/-) mice have reduced fat and preserve a healthier lipid profile. Old Ghsr(-/-) mice also exhibit elevated energy expenditure and resting metabolic rate, yet have similar food intake and locomotor activity. While GHS-R expression in white and brown adipose tissues was below the detectable level in the young mice, GHS-R expression was readily detectable in visceral white fat and interscapular brown fat of the old mice. Gene expression profiles reveal that Ghsr ablation reduced glucose/lipid uptake and lipogenesis in white adipose tissues but increased thermogenic capacity in brown adipose tissues. Ghsr ablation prevents age-associated decline in thermogenic gene expression of uncoupling protein 1 (UCP1). Cell culture studies in brown adipocytes further demonstrate that ghrelin suppresses the expression of adipogenic and thermogenic genes, while GHS-R antagonist abolishes ghrelins effects and increases UCP1 expression. Hence, GHS-R plays an important role in thermogenic impairment during aging. Ghsr ablation improves aging-associated obesity and insulin resistance by reducing adiposity and increasing thermogenesis. Growth hormone secretagogue receptor antagonists may be a new means of combating obesity by shifting the energy balance from obesogenesis to thermogenesis.
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Morphologic changes and prognosis of the respiratory tract epithelium in inhalation injury and their relationship with clinical manifestations.
Surgery
PUBLISHED: 07-07-2011
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We set out to observe the morphologic changes and determine prognosis based on airway epithelial injury after inhalation injury of varying severity using a fiberbronchoscope and to explore the relationship between the severity of epithelial injury and its clinical manifestation.
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The effect of anchoring group number on molecular structures and absorption spectra of triphenylamine sensitizers: a computational study.
J Mol Model
PUBLISHED: 05-19-2011
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The molecular structures and absorption spectra of triphenylamine dyes containing different numbers of anchoring groups (S1-S3) were investigated by density functional theory (DFT) and time-dependent DFT. The calculated geometries indicate that strong conjugation is formed in the dyes. The interfacial charge transfer between the TiO(2) electrode and S1-S3 are electron injection processes from the excited dyes to the semiconductor conduction band. The simulated absorption bands are assigned to ? ? ?* transitions according to the qualitative agreement between the experimental and calculated results. The effect of anchoring group number on the molecular structures, absorption spectra and photovoltaic performance were comparatively discussed.
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Magnetic resonance imaging features of soft tissue and vascular injuries after high-voltage electrical burns and their clinical application.
Injury
PUBLISHED: 04-11-2011
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To study the clinical application of MRI (magnetic resonance imaging) and MRA (MR angiography) technologies for examining the imaging characteristics of muscular and vascular injuries following high-voltage electrical burns.
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2D-DIGE proteomic analysis of changes in estrogen/progesterone-induced rat breast hyperplasia upon treatment with the Mongolian remedy RuXian-I.
Molecules
PUBLISHED: 01-26-2011
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RuXian-I has traditionally been used as a remedy for breast hyperplasia in the Inner Mongolia Autonomous Region of China. As a first step toward the investigation of biomarkers associated with RuXian-I treatment, a proteome-wide analysis of rat breast tissue was conducted. First, rat breast hyperplasia was induced by injection of estradiol and progesterone. After treatment with RuXian-I, there is a marked decrease in the hyperplasia, as can be shown by decreases in the nipple diameter and the pathological changes in breast. Subsequently, we used an approach that integrates size-based 2D-DIGE, MALDI-TOF/TOF-MS, and bioinformatics to analyze data from the control group, the model group and the RuXian-I treatment group. Using this approach, seventeen affected proteins were identified. Among these, 15 (including annexin A1, annexin A2, superoxide dismutase [Mn], peroxiredoxin-1, translationally-controlled tumor protein and a B-crystallin) were significantly up-regulated in the model group and down-regulated upon treatment with RuXian-I, and two (Tpil protein and myosin-4) have the opposite change trend. The expression of annexin A1 was confirmed using immunohistochemistry. The expression of superoxide dismutase (SOD) activity was confirmed biochemically. These results indicated that RuXian-I treats rat breast hyperplasia through regulation of cell cycle, immune system, metabolic, signal transduction, etc. The differential expressions of these proteins (annexin A1, superoxide dismutase [Mn], alpha B-crystallins and translationally controlled tumor protein, among others) were associated with occurrence and metastasis of breast cancer. These findings might provide not only far-reaching valuable insights into the mechanism of RuXian-I action, but also leads for prognosis and diagnosis of breast hyperplasia and breast cancer.
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Ablations of ghrelin and ghrelin receptor exhibit differential metabolic phenotypes and thermogenic capacity during aging.
PLoS ONE
PUBLISHED: 01-26-2011
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Obesity is a hallmark of aging in many Western societies, and is a precursor to numerous serious age-related diseases. Ghrelin (Ghrl), via its receptor (growth hormone secretagogue receptor, GHS-R), is shown to stimulate GH secretion and appetite. Surprisingly, our previous studies showed that Ghrl(-/-) mice have impaired thermoregulatory responses to cold and fasting stresses, while Ghsr(-/-) mice are adaptive.
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[The relationship between extend types and distant metastasis of nasopharyngeal carcinoma].
Lin Chung Er Bi Yan Hou Tou Jing Wai Ke Za Zhi
PUBLISHED: 09-03-2010
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To explore the relationship between extend types and distant metastasis of nasopharyngeal carcinoma (NPC).
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The biodegradation of zein in vitro and in vivo and its application in implants.
AAPS PharmSciTech
PUBLISHED: 08-23-2010
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A unique polymer-based sustained-release implant drug delivery system was prepared by using biocompatible and biodegradable Zein as the skeleton material. After preparing Zein colloids, the Zein-loaded implant rods were formulated by injection molding followed by evaporating the solvent, and being coated with poly(lactic-co-glycolic) acid (PLGA) solution. Drug release kinetics was examined by using Fluorouracil (5-FU) as model drug. Nearly zero-order release was achieved for the model drugs for a period of 0-25 days when the implants were incubated in distilled water at 37 °C. And then the degradation kinetics of the rods in vivo and in vitro were evaluated, which indicated that Zein could be absorbed by body and has good degradation property. The effects of different ratios of Zein/5-FU and the rods diameter on drug release were studied, respectively. The plasma concentration of 5-FU in the implants were determined by HPLC after implanting a single dose of the implants in rats. All data were subsequently processed by using the computer program 3P97, and the values were showed as follows: the area under the plasma concentration-time curve (AUC) value was 321.88 (?g/ml) × day, and the mean residence time (MRT) value was 23.05 days. The sustained-release implants of Zein/5-FU were successfully formulated. The uniqueness of the article is that Zein has been used as a skeleton material in implant delivery system for the first time and zero-order release kinetics has been obtained successfully.
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[Clinical experience of cervical trachea sleeve resection].
Lin Chung Er Bi Yan Hou Tou Jing Wai Ke Za Zhi
PUBLISHED: 08-13-2009
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To summarize the experience of cervical trachea sleeve resection.
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Using flowerlike polymer-copper nanostructure composite and novel organic-inorganic hybrid material to construct an amperometric biosensor for hydrogen peroxide.
Colloids Surf B Biointerfaces
PUBLISHED: 05-26-2009
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A new type of amperometric hydrogen peroxide biosensor was fabricated by entrapping horseradish peroxidase (HRP) in the organic-inorganic hybrid material composed of zirconia-chitosan sol-gel and Au nanoparticles (ZrO2-CS-AuNPs). The sensitivity of the biosensor was enhanced by a flowerlike polymer-copper nanostructure composite (pPA-FCu) which was prepared from co-electrodeposition of CuSO4 solution and 2,6-pyridinediamine solution. Several techniques, including UV-vis absorption spectroscopy, scanning electron microscopy, cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy were employed to characterize the assembly process and performance of the biosensor. The results showed that this pPA-FCu nanostructure not only had excellent redox electrochemical activity, but also had good catalytic efficiency for hydrogen peroxide. Also the ZrO2-CS-AuNPs had good film forming ability, high stability and good retention of bioactivity of the immobilized enzyme. The resulting biosensors showed a linear range from 7.80 x 10(-7) to 3.7 x 10(-3) mol L(-1), with a detection limit of 3.2 x 10(-7) mol L(-1) (S/N=3) under optimized experimental conditions. The apparent Michaelis-Menten constant was determined to be 0.32 mM, showing good affinity. In addition, the biosensor which exhibits good analytical performance, acceptable stability and good selectivity, has potential for practical applications.
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Thermogenic characterization of ghrelin receptor null mice.
Meth. Enzymol.
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Ghrelin is the only known circulating orexigenic hormone that increases food intake and promotes adiposity, and these physiological functions of ghrelin are mediated through its receptor growth hormone secretagogue receptor (GHS-R). Ghrelin/GHS-R signaling plays a crucial role in energy homeostasis. Old GHS-R null mice exhibit a healthy phenotype-lean and insulin sensitive. Interestingly, the GHS-R null mice have increased energy expenditure, yet exhibit no difference in food intake or locomotor activity compared to wild-type mice. We have found that GHS-R is expressed in brown adipose tissue (BAT) of old mice. Ablation of GHS-R attenuates age-associated decline in thermogenesis, exhibiting a higher core body temperature. Indeed, the BAT of old GHS-R null mice reveals enhanced thermogenic capacity, which is consistent with the gene expression profile of increases in glucose/lipid uptake, lipogenesis, and lipolysis in BAT. The data collectively suggest that ghrelin/GHS-R signaling has important roles in thermogenesis. The recent discovery that BAT also regulates energy homeostasis in adult humans makes the BAT a new antiobesity target. Understanding the roles and molecular mechanisms of ghrelin/GHS-R in thermogenesis is of great significance. GHS-R antagonists might be a novel means of combating obesity by shifting adiposity balance from obesogenesis to thermogenesis.
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Legumes can increase cadmium contamination in neighboring crops.
PLoS ONE
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Legumes are widely used in many cropping systems because they share their nitrogen fixation products and phosphorus mobilization activities with their neighbors. In the current study, however, we showed that co-cultivation with legumes increased cadmium (Cd) contamination in the adjacent crops. Both field and mesocosm experiments indicated that legumes increased Cd levels in edible parts and shoots of four neighboring crops and five maize varieties tested, regardless of the Cd levels in the soil. This enhanced Cd accumulation in crops was attributed to root interactions that alter the rhizosphere environment. Co-cultivation with legumes reduced soil pH, which somewhat increased the exchangeable forms of Cd. Our results have demonstrated the inevitable increases in Cd levels of crops as a direct result of co-cultivation with legumes even under situations when these levels are below the permissible threshold. With this new revelation, we need to consider carefully the current cropping systems involving legumes and perhaps to re-design the current and future cropping systems in view of avoiding food contamination by Cd.
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Interface driven energy filtering of thermoelectric power in spark plasma sintered Bi(2)Te(2.7)Se(0.3) nanoplatelet composites.
Nano Lett.
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Control of competing parameters such as thermoelectric (TE) power and electrical and thermal conductivities is essential for the high performance of thermoelectric materials. Bulk-nanocomposite materials have shown a promising improvement in the TE performance due to poor thermal conductivity and charge carrier filtering by interfaces and grain boundaries. Consequently, it has become pressingly important to understand the formation mechanisms, stability of interfaces and grain boundaries along with subsequent effects on the physical properties. We report here the effects of the thermodynamic environment during spark plasma sintering (SPS) on the TE performance of bulk-nanocomposites of chemically synthesized Bi(2)Te(2.7)Se(0.3) nanoplatelets. Four pellets of nanoplatelets powder synthesized in the same batch have been made by SPS at different temperatures of 230, 250, 280, and 350 °C. The X-ray diffraction, transmission electron microscopy, thermoelectric, and thermal transport measurements illustrate that the pellet sintered at 250 °C shows a minimum grain growth and an optimal number of interfaces for efficient TE figure of merit, ZT?0.55. For the high temperature (350 °C) pelletized nanoplatelet composites, the concurrent rise in electrical and thermal conductivities with a deleterious decrease in thermoelectric power have been observed, which results because of the grain growth and rearrangements of the interfaces and grain boundaries. Cross section electron microscopy investigations indeed show significant grain growth. Our study highlights an optimized temperature range for the pelletization of the nanoplatelet composites for TE applications. The results provide a subtle understanding of the grain growth mechanism and the filtering of low energy electrons and phonons with thermoelectric interfaces.
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Substituent effect on the ? linkers in triphenylamine dyes for sensitized solar cells: a DFT/TDDFT study.
Chemphyschem
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A series of metal-free organic donor-? bridge-acceptor dyes are studied computationally using density functional theory (DFT) and time-dependent DFT (TDDFT) approaches to explore their potential performances in dye-sensitized solar cells (DSSCs). Taking triphenylamine (TPA) and cyanoacrylic acid moieties as donor and acceptor units, respectively, the effects of different substituents of the ? linkers in the TPA-based dyes on the energy conversion efficiency of the DSSCs are theoretically evaluated through optimized geometries, charge distributions, electronic structures, simulated absorption spectra, and free energies of injection. The results show that the molecular orbital energy levels and electron-injection driving forces of the TPA dyes can be tuned by the introduction of substituents with different electron-withdrawing or -donating abilities. The electron-withdrawing substituent always lowers the energies of both frontier orbitals, while the electron-donating one heightens them simultaneously. The efficiency trend of these TPA derivatives as sensitizers in DSSCs is also predicted by analyzing the light-harvesting efficiencies and the free energies of injection. The following substituents are shown to increase the efficiency of the dye: OMe, OEt, OHe, and OH.
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Ablation of ghrelin receptor in leptin-deficient ob/ob mice has paradoxical effects on glucose homeostasis when compared with ablation of ghrelin in ob/ob mice.
Am. J. Physiol. Endocrinol. Metab.
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The orexigenic hormone ghrelin is important in diabetes because it has an inhibitory effect on insulin secretion. Ghrelin ablation in leptin-deficient ob/ob (Ghrelin(-/-):ob/ob) mice increases insulin secretion and improves hyperglycemia. The physiologically relevant ghrelin receptor is the growth hormone secretagogue receptor (GHS-R), and GHS-R antagonists are thought to be an effective strategy for treating diabetes. However, since some of ghrelins effects are independent of GHS-R, we have utilized genetic approaches to determine whether ghrelins effect on insulin secretion is mediated through GHS-R and whether GHS-R antagonism indeed inhibits insulin secretion. We investigated the effects of GHS-R on glucose homeostasis in Ghsr-ablated ob/ob mice (Ghsr(-/-):ob/ob). Ghsr ablation did not rescue the hyperphagia, obesity, or insulin resistance of ob/ob mice. Surprisingly, Ghsr ablation worsened the hyperglycemia, decreased insulin, and impaired glucose tolerance. Consistently, Ghsr ablation in ob/ob mice upregulated negative ?-cell regulators (such as UCP-2, SREBP-1c, ChREBP, and MIF-1) and downregulated positive ?-cell regulators (such as HIF-1?, FGF-21, and PDX-1) in whole pancreas; this suggests that Ghsr ablation impairs pancreatic ?-cell function in leptin deficiency. Of note, Ghsr ablation in ob/ob mice did not affect the islet size; the average islet size of Ghsr(-/-):ob/ob mice is similar to that of ob/ob mice. In summary, because Ghsr ablation in leptin deficiency impairs insulin secretion and worsens hyperglycemia, this suggests that GHS-R antagonists may actually aggravate diabetes under certain conditions. The paradoxical effects of ghrelin ablation and Ghsr ablation in ob/ob mice highlight the complexity of the ghrelin-signaling pathway.
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QSPR studies of impact sensitivity of nitro energetic compounds using three-dimensional descriptors.
J. Mol. Graph. Model.
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The quantitative structure-property relationship (QSPR) studies were performed between molecular structures and impact sensitivity for a diverse set of nitro energetic compounds based on three-dimensional (3D) descriptors. The entire set of 156 compounds was divided into a training set of 127 compounds and a test set of 29 compounds according to Kennard and Stones algorithm. Multiple linear regression (MLR) analysis was employed to select the best subset of descriptors and to build linear models; while nonlinear models were developed by means of artificial neural network (ANN). The obtained models with ten descriptors involved show good predictive power for the test set: a squared correlation coefficient (R²) of 0.7222 and a standard error of estimation (s) of 0.177 were achieved by the MLR model; while by the ANN model, R² and s were 0.8658 and 0.130, respectively. Therefore, the proposed models can be used to predict the impact sensitivity of new nitro compounds for engineering.
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Adipocyte expression of PU.1 transcription factor causes insulin resistance through upregulation of inflammatory cytokine gene expression and ROS production.
Am. J. Physiol. Endocrinol. Metab.
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We have reported previously that ETS family transcription factor PU.1 is expressed in mature adipocytes of white adipose tissue. PU.1 expression is increased greatly in mouse models of genetic or diet-induced obesity. Here, we show that PU.1 expression is increased only in visceral but not subcutaneous adipose tissues of obese mice, and the adipocytes are responsible for this increase in PU.1 expression. To further address PU.1s physiological function in mature adipocytes, PU.1 was knocked down in 3T3-L1 cells using retroviral-mediated expression of PU.1-targeting shRNA. Consistent with previous findings that PU.1 regulates its target genes, such as NADPH oxidase subunits and proinflammatory cytokines in myeloid cells, the mRNA levels of proinflammatory cytokines (TNF?, IL-1?, and IL-6) and cytosolic components of NADPH oxidase (p47phox and p40phox) were downregulated significantly in PU.1-silenced adipocytes. NADPH oxidase is a main source for reactive oxygen species (ROS) generation. Indeed, silencing PU.1 suppressed NADPH oxidase activity and attenuated ROS in basal or hydrogen peroxide-treated adipocytes. Silencing PU.1 in adipocytes suppressed JNK1 activation and IRS-1 phosphorylation at Ser(307). Consequently, PU.1 knockdown improved insulin signaling and increased glucose uptake in basal and insulin-stimulated conditions. Furthermore, knocking down PU.1 suppressed basal lipolysis but activated stimulated lipolysis. Collectively, these findings indicate that obesity induces PU.1 expression in adipocytes to upregulate the production of ROS and proinflammatory cytokines, both of which lead to JNK1 activation, insulin resistance, and dysregulation of lipolysis. Therefore, PU.1 might be a mediator for obesity-induced adipose inflammation and insulin resistance.
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Enhanced thermoelectric properties of solution grown Bi2Te(3-x)Se(x) nanoplatelet composites.
Nano Lett.
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We report on the enhanced thermoelectric properties of selenium (Se) doped bismuth telluride (Bi(2)Te(3-x)Se(x)) nanoplatelet (NP) composites synthesized by the polyol method. Variation of the Se composition within NPs is demonstrated by X-ray diffraction and Raman spectroscopy. While the calculated lattice parameters closely follow the Vegards law, a discontinuity in the shifting of the high frequency (E(g)(2) and A(1g)(2)) phonon modes illustrates a two mode behavior for Bi(2)Te(3-x)Se(x) NPs. The electrical resistivity (?) of spark plasma sintered pellet composites shows metallic conduction for pure Bi(2)Te(3) NP composites and semiconducting behavior for intermediate Se compositions. The thermal conductivity (?) for all NP composites is much smaller than the bulk values and is dominated by microstructural grain boundary scattering. With temperature dependent electrical and thermal transport measurements, we show that both the thermoelectric power S (-259 ?V/K) and the figure of merit ZT (0.54) are enhanced by nearly a factor of 4 for SPS pellets of Bi(2)Te(2.7)Se(0.3) in comparison to Bi(2)Te(3) NP composites. Tentatively, such an enhancement of the thermoelectric performance in nanoplatelet composites is attributed to the energy filtering of low energy electrons by abundant grain boundaries in aligned nanocomposites.
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