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1.
Effects of hyperthyroidism and hypothyroidism on glutamine metabolism by skeletal muscle of the rat.
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M Parry-Billings G D Dimitriadis B Leighton J Bond S J Bevan E Opara E A Newsholme 《The Biochemical journal》1990,272(2):319-322
1. The effects of hyperthyroidism and hypothyroidism on the concentrations of glutamine and other amino acids in the muscle and plasma and on the rates of glutamine and alanine release from incubated isolated stripped soleus muscle of the rat were investigated. 2. Hyperthyroidism decreased the concentration of glutamine in soleus muscle but was without effect on that in the gastrocnemius muscle or in the plasma. Hyperthyroidism also increased markedly the rate of release of glutamine from the incubated soleus muscle. 3. Hypothyroidism decreased the concentrations of glutamine in the gastrocnemius muscle and plasma but was without effect on that in soleus muscle. Hypothyroidism also decreased markedly the rate of glutamine release from the incubated soleus muscle. 4. Thyroid status was found to have marked effects on the rate of glutamine release by skeletal muscle per se, and may be important in the control of this process in both physiological and pathological conditions. 相似文献
2.
The conversion of eremoacetal to (?)-1-(furan-3-yl)-4-hydroxy-4,8-dimethylnonane-1,6-dione establishes the configuration of (?)-4-hydroxymyoporone (athanagrandione) as R. 相似文献
3.
Melpomeni Peppa Chrysi Koliaki Athanasios Papaefstathiou Efstathios Garoflos Nicholas Katsilambros Sotirios A. Raptis Dimitrios I. Hadjidakis George D. Dimitriadis 《Obesity (Silver Spring, Md.)》2013,21(9):1807-1814
Objective : Although obesity is typically associated with increased cardiovascular risk, a subset of obese individuals display a normal metabolic profile (“metabolically healthy obese,” MHO) and conversely, a subset of nonobese subjects present with obesity‐associated cardiometabolic abnormalities (“metabolically obese nonobese,” MONO). The aim of this cross‐sectional study was to identify the most important body composition determinants of metabolic phenotypes of obesity in nonobese and obese healthy postmenopausal women. Design and Methods : We studied a total of 150 postmenopausal women (age 54 ± 7 years, mean ± 1 SD). Based on a cardiometabolic risk score, nonobese (body mass index [BMI] ≤ 27) and obese women (BMI > 27) were classified into “metabolically healthy” and “unhealthy” phenotypes. Total and regional body composition was assessed with dual‐energy X‐ray absorptiometry (DXA). Results : In both obese and nonobese groups, the “unhealthy” phenotypes were characterized by frequent bodyweight fluctuations, higher biochemical markers of insulin resistance, hepatic steatosis and inflammation, and higher anthropometric and DXA‐derived indices of central adiposity, compared with “healthy” phenotypes. Indices of total adiposity, peripheral fat distribution and lean body mass were not significantly different between “healthy” and “unhealthy” phenotypes. Despite having increased fat mass, MHO women exhibited comparable cardiometabolic parameters with healthy nonobese, and better glucose and lipid levels than MONO. Two DXA‐derived indices, trunk‐to‐legs and abdominal‐to‐gluteofemoral fat ratio were the major independent determinants of the “unhealthy” phenotypes in our cohort. Conclusions : The “metabolically obese phenotype” is associated with bodyweight variability, multiple cardiometabolic abnormalities and an excess of central relative to peripheral fat in postmenopausal women. DXA‐derived centrality ratios can discriminate effectively between metabolic subtypes of obesity in menopause. 相似文献
4.
M Parry-Billings B Leighton G D Dimitriadis R Curi J Bond S Bevan A Colquhoun E A Newsholme 《The International journal of biochemistry》1991,23(9):933-937
1. The effects of tumour bearing on glutamine metabolism in rat skeletal muscle were examined using the Walker 256 carcinosarcoma. 2. There was a rapid and marked decrease in skeletal muscle glutamine content, which was correlated with the size of the tumour, and a decrease in plasma glutamine concentration. 3. The rate of release of glutamine from EDL muscle in vitro was increased in cachectic, tumour bearing animals, but was unaffected from the soleus muscle of the same animals. 4. It is hypothesized that the increase in the rate of muscle glutamine release during cachexia represents a response of this tissue in order to satisfy the demand for glutamine by the tumour or by cells of the immune system. 相似文献
5.
The epithelium of the digestive tubules of the mussel Mytilus galloprovincialis is comprised of two cell types, namely digestive and basophilic cells. In basophilic cells, the secretory granules are beta-glucuronidase immunoreactive, a fact that enhances the hypothesis that beta-glucuronidase is synthesized in basophilic cells. A novel observation at the ultrastructural level is the pinocytic activity associated with the formation of coated pits. This observation constitutes direct evidence for endocytic processes taking place in basophilic cells. The use of cryostat sections from the same digestive tubules reveals, in many instances, a very pronounced neutral lipid accumulation in the same structures giving a positive reaction for N-acetyl-beta-hexosaminidase, indicating the association of those lipids with lysosomes. In some mussels, a high content of lipofuscin was observed in the lysosomes of the digestive cells. In these cases, the lysosomal structures show a limited neutral lipid content, and a weaker N-acetyl-beta-hexosaminidase reaction. In the digestive cells, the carbohydrate content of the lysosomes, and very well-developed canal system in the apical part of cells are discussed in relation to their function. 相似文献
6.
In the present study, autometallography (AMG) has been performed on resin-embedded tissue sections, cryosections, as well as on isolated cells from the digestive gland, the gills and the haemolymph of mussels (Mytilus galloprovincialis) collected from the field. The AMG reaction was more intense in cryosections and isolated cells compared to resin sections. This intense AMG reaction found in cryosections and in isolated cells and the time effectiveness of the procedures enhances their use in a variety of studies, such as biomonitoring, even if small amount of metals are to be detected. In addition, the preparation of isolated cells does not require specific instruments or qualified personnel and, thus, the use of isolated cells is encouraging for AMG applications, although further laboratory investigation is required. On the other hand, the use of resin-embedded tissue sections for AMG applications, even though it is complicated and time consuming, leads to a high preservation of structural morphology and allows the exact localization of metals in discrete cellular compartments. 相似文献
7.
Determination of elastic moduli of thin layers of soft material using the atomic force microscope 总被引:2,自引:0,他引:2
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We address three problems that limit the use of the atomic force microscope when measuring elastic moduli of soft materials at microscopic scales. The first concerns the use of sharp cantilever tips, which typically induce local strains that far exceed the linear material regime. We show that this problem can be alleviated by using microspheres as probes, and we establish the criteria for their use. The second relates to the common use of the Hertz contact mechanics model, which leads to significant errors when applied to thin samples. We develop novel, simple to use corrections to apply for such cases. Samples that are either bonded or not bonded to a rigid substrate are considered. The third problem concerns the difficulty in establishing when contact occurs on a soft material. We obtain error estimates for the elastic modulus resulting from such uncertainty and discuss the sensitivity of the estimation methods to error in contact point. The theoretical and experimental results are compared to macroscopic measurements on poly(vinyl-alcohol) gels. 相似文献
8.
Abstract Chironomidae (Insecta: Diptera: non-biting midges) were surveyed at five shallow riffle stations along the estuarine gradient of the Clyde River, southern New South Wales (35°45'S, 150°15'E). Benthic populations were sampled seasonally between April 2001 and January 2002, between an uppermost fully fresh station and 7 km south of the tidal limit at Shallow Crossing, encompassing a 23 km stretch. Biological structure and integrity of chironomid assemblages, which are essentially unknown in eastern Australia's estuarine environments, were elucidated. Assemblages were diverse: from 5732 chironomid larvae, 45 species belonging to four subfamilies were identified from riffles. All chironomid assemblages were strongly structured and non-random with respect to spatial position along the salinity gradient although relatively random with respect to temporal shifts between the five seasonal samples. Generally, the salinity gradient had strong effects on assemblage composition but no discrete brackish fauna was identifiable, and the abundance of many species declined gradually with distance from the freshest station. Dominant taxa in the brackish zone were Parakiefferiella ' variegatus ' and two species of Cladotanytarsus . Notably, the little-known Semiocladius crassipennis Skuse (Orthocladiinae) was abundant at the most marine-influenced station. Taxa present exclusively in freshwaters included several Tanypodinae notably absent from sites below Shallow Crossing at salinities normally tolerated in athalassic waters. Other species restricted to freshwaters included Nanocladius sp., Demicryptochironomus (Irmakia) sp., Polypedilum vespertinus (Skuse), Zavrelliella fuscoguttata (Kieffer), Riethia stictoptera (Kieffer) and Podonomopsis sp. 相似文献
9.
Yeast-based biomass, immobilised in polyvinyl alcohol (PVA) cryogels, was used as a biosorbant material for the recovery of
platinum (PtCl62−) from aqueous solutions. The resulting biomass-Pt matrices were then employed directly as an electro-catalytic anode in a
fuel cell configuration to generate electrical energy from renewable sources such as glucose and ethanol. We suggest an integrated
strategy incorporating the derivation of a high-value product from a bioremediative process with a view towards producing
energy from renewable fuels such as glucose and ethanol. 相似文献
10.
Comparative study of Cd(II) and Cr(VI) biosorption on Staphylococcus xylosus and Pseudomonas sp. in single and binary mixtures 总被引:1,自引:0,他引:1
Ziagova M Dimitriadis G Aslanidou D Papaioannou X Litopoulou Tzannetaki E Liakopoulou-Kyriakides M 《Bioresource technology》2007,98(15):2859-2865
Biosorption of Cd(II) and Cr(VI) ions in single solutions using Staphylococcus xylosus and Pseudomonas sp., and their selectivity in binary mixtures was investigated. Langmuir and Freundlich models were applied to describe metal biosorption and the influence of pH, biomass concentration and contact time was determined. Maximum uptake capacity of cadmium was estimated to 250 and 278 mg g(-1), whereas that of chromium to 143 and 95 mg g(-1) for S. xylosus and Pseudomonas sp., respectively. In binary mixtures with Cd(II) ions as the dominant species, there is a profound selectivity for cadmium biosorption, reaching 96% and 89% for Pseudomonas sp. and S. xylosus, respectively, at 10 mg l(-1) Cd(II) and 5 mg l(-1) Cr(VI). Interesting, when chromium (VI) ions are the dominant species, there is selectivity towards chromium around 92% with S. xylosus only. 相似文献