排序方式: 共有210条查询结果,搜索用时 15 毫秒
51.
Xuefeng Zhang Chengcheng Zhu Wenjia Peng Bing Tian Luguang Chen Zhongzhao Teng Jianping Lu Umar Sadat David Saloner Qi Liu 《PloS one》2015,10(8)
Purpose
To evaluate the scan-rescan reproducibility of high-resolution magnetic resonance imaging (MRI) of middle cerebral artery (MCA) plaque, and calculate the number of subjects needed for future longitudinal clinical studies.Material and Methods
Twenty two patients with MCA plaque were scanned twice by a T2-weighted fast-spin-echo sequence at 3T. Areas and volumes of MCA lumen, total vessel and plaque were quantified and compared between two repeated scans. Agreement and measurement error was quantified by intraclass correlation coefficient (ICC) and coefficient of variance (CV) as defined by standard deviation (SD) of pair wise difference / mean. Sample size needed to detect 5% to 20% changes in area/volume was calculated using 80% power and 5% significance level.Results
There was no significant different between the area and volume measurements of two repeated scans (p>0.05) with good agreement (ICC range 0.97–0.98 for area and 0.99 for volume). Relatively small measurement errors were observed with CVs range 6.1%-11.8% for area quantification and 4.9%-8.0% for volume quantification. Volume measurements tended to have 19.7% to 32.2% smaller CVs compared with area measurements. Sample size calculation showed a group of 47 patients was sufficient to detect 5% to 10% changes in MCA area/volume.Conclusion
High resolution MRI is feasible for quantifying intracranial plaque area and volume in longitudinal clinical studies with low scan-rescan variability. Volume measurement tends to be more reproducible compared with area measurements. 相似文献52.
Maximilian Bielohuby Sayyed Hamid Zarkesh-Esfahani Jenny Manolopoulou Elisa Wirthgen Katja Walpurgis Mohaddeseh Toghiany Khorasgani Zahra Sadat Aghili Ian Robert Wilkinson Andreas Hoeflich Mario Thevis Richard J. Ross Martin Bidlingmaier 《Disease models & mechanisms》2014,7(11):1263-1273
The development of new growth hormone (GH) agonists and growth hormone antagonists (GHAs) requires animal models for pre-clinical testing. Ideally, the effects of treatment are monitored using the same pharmacodynamic marker that is later used in clinical practice. However, intact rodents are of limited value for this purpose because serum IGF-I, the most sensitive pharmacodynamic marker for the action of GH in humans, shows no response to treatment with recombinant human GH and there is little evidence for the effects of GHAs, except when administered at very high doses or when overexpressed. As an alternative, more suitable model, we explored pharmacodynamic markers of GH action in intact rabbits. We performed the first validation of an IGF-I assay for the analysis of rabbit serum and tested precision, sensitivity, linearity and recovery using an automated human IGF-I assay (IDS-iSYS). Furthermore, IGF-I was measured in rabbits of different strains, age groups and sexes, and we monitored IGF-I response to treatment with recombinant human GH or the GHA Pegvisomant. For a subset of samples, we used LC-MS/MS to measure IGF-I, and quantitative western ligand blot to analyze IGF-binding proteins (IGFBPs). Although recovery of recombinant rabbit IGF-I was only 50% in the human IGF-I assay, our results show that the sensitivity, precision (1.7–3.3% coefficient of variation) and linearity (90.4–105.6%) were excellent in rabbit samples. As expected, sex, age and genetic background were major determinants of IGF-I concentration in rabbits. IGF-I and IGFBP-2 levels increased after single and multiple injections of recombinant human GH (IGF-I: 286±22 versus 434±26 ng/ml; P<0.01) and were highly correlated (P<0.0001). Treatment with the GHA lowered IGF-I levels from the fourth injection onwards (P<0.01). In summary, we demonstrated that the IDS-iSYS IGF-I immunoassay can be used in rabbits. Similar to rodents, rabbits display variations in IGF-I depending on sex, age and genetic background. Unlike in rodents, the IGF-I response to treatment with recombinant human GH or a GHA closely mimics the pharmacodynamics seen in humans, suggesting that rabbits are a suitable new model to test human GH agonists and antagonists.KEY WORDS: Pharmacodynamic marker, Acromegaly, Growth hormone deficiency, Animal model 相似文献
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Fatemeh Fotouhi Mostafa Salehi-Vaziri Behrokh Farahmand Ehsan Mostafavi Mohammad Hassan Pouriayevali Tahmineh Jalali Vahideh Mazaheri Mona Sadat Larijani Mahsa Tavakoli Azita Eshratkhah mohammadnejad Neda Afzali Afsaneh Zokaei SeyedeAtefe Hosseini Mohamad Mahdi Mortazavipour FaridehNiknam Oskouei Amitis Ramezani 《Microbes and infection / Institut Pasteur》2021,23(4-5):104810
SARS-CoV-2 as a new global threat has affected global population for one year. Despite the great effort to eradicate this infection, there are still some challenges including different viral presentation, temporal immunity in infected individuals and variable data of viral shedding. We studied 255 COVID-19 suspected individuals to assess the viral shedding duration and also the antibody development against SARS-CoV-2 among the cases. Real Time RT-PCR assay was applied to determine the virus presence and SARS-CoV-2 antibodies were evaluated using SARS-CoV-2 IgM and IgG kits. 113 patients were confirmed for COVID-19 infection. The patients were followed until negative PCR achieved. The median viral shedding among studied population was obtained 34.16 (±17.65) days which was not significantly associated with age, sex and underlying diseases. Shiver and body pain were found in prolonged form of the infection and also patients who had gastrointestinal problems experienced longer viral shedding. Moreover, IgG was present in 84% of patients after 150 days. According to this data, the median viral shedding prolongation was 34.16 days which indicates that 14 days isolation might not be enough for population. In addition, IgG profiling indicated that it is persistent in a majority of patients for nearly 6 months which has brought some hopes in vaccine efficacy and application. 相似文献
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Azita Zadeh-Vakili Fahimeh Ramezani Tehrani Maryam Sadat Daneshpour Maryam Zarkesh Navid Saadat Fereidoun Azizi 《Gene》2013
Aims
Polycystic ovary syndrome (PCOS), a common female endocrine disorder, represents a wide range of clinical manifestations and disease severity. Recent studies suggest an association between gene variants involved in vitamin D metabolism and common metabolic disturbances in PCOS. We aimed to examine the association of vitamin D receptor (VDR) gene variant with PCOS susceptibility and the severity of disease phenotype.Methods
All participants, including 260 PCOS women (cases) and 221 normoovulatory women (controls), were recruited from a reproductive endocrinology clinic. Cases were divided into the severe and mild PCOS phenotype groups, based on their clinical and paraclinical features. An adenosine to guanine single nucleotide polymorphism of VDR gene (rs757343) was genotyped using the PCR–RFLP method.Results
Distributions of genotypes and alleles did not differ between cases and controls, indicating that this SNP is not associated with increased risk for PCOS. However, this SNP was found to be associated with the severity of the PCOS phenotype. In particular, presence of the A allele is associated with a 74% increased risk of severe phenotype development (OR, 1.74; 95% CI, 1.07–2.82).Conclusion
The genetic variant of the VDR was found to have an association with severity of clinical features of PCOS, but none with disease risk. 相似文献57.
Khattab SM Watanabe S Saimura M Kodaki T 《Biochemical and biophysical research communications》2011,(2):634-637
Xylose reductase (XR) and xylitol dehydrogenase (XDH) are the key enzymes for xylose fermentation and have been widely used for construction of a recombinant xylose fermenting yeast. The effective recycling of cofactors between XR and XDH has been thought to be important to achieve effective xylose fermentation. Efforts to alter the coenzyme specificity of XR and HDX by site-directed mutagenesis have been widely made for improvement of efficiency of xylose fermentation. We previously succeeded by protein engineering to improve ethanol production by reversing XDH dependency from NAD+ to NADP+. In this study, we applied protein engineering to construct a novel strictly NADPH-dependent XR from Pichia stipitis by site-directed mutagenesis, in order to recycle NADPH between XR and XDH effectively. One double mutant, E223A/S271A showing strict NADPH dependency with 106% activity of wild-type was generated. A second double mutant, E223D/S271A, showed a 1.27-fold increased activity compared to the wild-type XR with NADPH and almost negligible activity with NADH. 相似文献
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Aghajani Mohammad Hajijafari Mohammad Akbari Hossein Asgarian Fatemeh Sadat 《Sleep and biological rhythms》2020,18(3):209-215
Sleep and Biological Rhythms - The purpose of this study was to assess the validity and reliability of the Persian version of the Cleveland Adolescent Sleepiness Questionnaire (CASQ) in Iranian... 相似文献
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Toghraie Fatemeh Sadat Ghaderi Abbas Ramezani Amin 《International journal of peptide research and therapeutics》2020,26(1):43-51
International Journal of Peptide Research and Therapeutics - Granulocyte colony-stimulating factor (G-CSF) is known as the major mediator of granulopoiesis. However, overexpression of G-CSF has... 相似文献
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Ghodrati Atefe Firoozpour Loghman Balalaie Saeed Hosseini Faezeh Sadat Ramezanpour Sorour Edraki Najme Mohtavinejad Naser Amanlou Massoud 《International journal of peptide research and therapeutics》2020,26(4):2169-2177
International Journal of Peptide Research and Therapeutics - β-secretase 1 (BACE1) plays a pivotal role in the pathology of Alzheimer?s disease via accumulation beta amyloid in the... 相似文献