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11.
Analysis of γ-Aminobutyric AcidA Receptor Subunits in the Mouse Cochlea by Means of the Polymerase Chain Reaction 总被引:1,自引:0,他引:1
Dennis G. Drescher Glenn E. Green Khalid M. Khan† Kavita Hajela Kirk W. Beisel Barbara J. Morley Anil K. Gupta 《Journal of neurochemistry》1993,61(3):1167-1170
Abstract: Unlike 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), which produces consistent decreases in levels of striatal dopamine (DA) with considerably smaller and more variable effects on mouse brain levels of serotonin (5-HT) and norepinephrine (NE), a novel amine-substituted MPTP analogue, 1-methyl-4-(2'-aminophenyl)-1,2,3,6-tetrahydropyridine (2'-NH2 -MPTP), administered in a standard mouse dosing paradigm for MPTP (20 mg/kg X 4) did not affect striatal DA but led to marked reductions (60–70%) in levels of 5-HT, 5-hydroxyindoleacetic acid (5-HIAA), and NE measured in frontal cortex and hippocampus 1 week after treatment. Another 2'-substituted MPTP analogue, 1-methyl-4-(2'-methylphenyl)-1,2,3,6-tetrahydropyridine, affected cortical and hippocampal 5-HT, 5-HIAA, and NE only minimally, while markedly reducing the DA content in striatum (90%), thus indicating that the substituent (-NH2 versus -CH3 ) at the 2'position is important for the differential effects of these MPTP analogues. In a replication study with a 3-week end point, hippocampal and cortical 5-HT, 5-HIAA, and NE levels remained depressed with no indication of recovery. These results suggest that 2'-NH2 -MPTP may be a novel, regionally selective neurotoxin for serotonergic and norad-renergic nerve terminals. 相似文献
12.
Khalid Meksem Dario Leister Johan Peleman Marc Zabeau Francesco Salamini Christiane Gebhardt 《Molecular & general genetics : MGG》1995,249(1):74-81
The R1 allele confers on potato a race-specific resistance to Phytophthora infestans. The corresponding genetic locus maps on chromosome V in a region in which several other resistance genes are also located. As part of a strategy for cloning R1, a high-resolution genetic map was constructed for the segment of chromosome V that is bordered by the RFLP loci GP21 and GP179 and includes the R1 locus. Bulked segregant analysis and markers based on amplified fragment length polymorphisms (AFLP markers) were used to select molecular markers closely linked to R1. Twenty-nine of approximately 3200 informative AFLP loci displayed linkage to the R1 locus. Based on the genotypic analysis of 461 gametes, eight loci mapped within the GP21–GP179 interval. Two of those could not be seperated from R1 by recombination. For genotyping large numbers of plants with respect to the flanking markers GP21 and GP179 PCR based assays were also developed which allowed marker-assisted selection of plants with genotypes Rr and rr and of recombinant plants. 相似文献
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Phosphatase Activity Toward Abnormally Phosphorylated τ: Decrease in Alzheimer Disease Brain 总被引:1,自引:0,他引:1
Cheng-Xin Gong Sadia Shaikh Jian-Zhi Wang Tanweer Zaidi Inge Grundke-Iqbal Khalid Iqbal 《Journal of neurochemistry》1995,65(2):732-738
Abstract: Microtubule-associated protein τ is abnormally hyperphosphorylated and aggregated in affected neurons of Alzheimer disease brain. This hyperphosphorylated τ can be dephosphorylated at some of the abnormal phosphorylated sites by purified protein phosphatase-1, 2A, and 2B in vitro. In the present study, we have developed an assay to measure protein phosphatase activity toward τ-1 sites (Ser199 /Ser202 ) using the hyperphosphorylated τ isolated from Alzheimer disease brain as substrate. Using this assay, we have identified that in normal brain, protein phosphatase-2A and 2B and, to a lesser extent, 1 are involved in the dephosphorylation of τ. The K m values of dephosphorylation of the hyperphosphorylated τ by protein phosphatase-2A and 2B are similar. The τ phosphatase activity is decreased by ∼30% in brain of Alzheimer disease patients compared with those of age-matched controls. These findings suggest that a defect of protein phosphatase could be the cause of the abnormal hyperphosphorylation of τ in Alzheimer disease. 相似文献
15.
Khalid M. Chraibi B. Alain Latche Jean-Paul Roustan Jean Fallot 《Plant cell reports》1991,10(4):204-207
The effects of CoCl2, AgNO3 and ethylene released by exogenous 2-chloroethylphosphonic acid (Ethephon), were studied on shoot regeneration from cotyledons of Helianthus annuus cv. E8206R, a poorly regenerative cultivar. Inhibition of ethylene biosynthesis by CoCl2, at concentrations of 20 K, provoked a substantial enhancement of shoot regeneration (30 %): the control was poorly regenerative. However, CoCl2 had no effect when Ethephon was supplied. Inhibition of ethylene action by AgNO3, at concentrations of 10–25 M, caused a significant increase in plant regeneration: 25 % instead of 1.2 % in the control. Furthermore, addition of Ethephon to AgNO3-treated tissues failed to reduce the stimulation of shoot regeneration caused by AgNO3. On the basis of these findings, it is suggested that ethylene inhibits the regeneration process from cotyledons of sunflower.Abbreviations NAA
1-naphthalene acetic acid
- BAP
6-benzylamino-purine
- GA3
gibberellic acid
- Ethephon
2-chloroethylphosphonic acid
- MS
Murashige and Skoog medium
- AVG
aminoethoxyvinylglycine 相似文献
16.
Purification and Partial Characterization of a Prolyl-Dipeptidyl Aminopeptidase from Lactobacillus helveticus CNRZ 32 总被引:8,自引:6,他引:2 下载免费PDF全文
X-prolyl-dipeptidyl aminopeptidase, which hydrolyzed Gly-Pro-p-nitroanilide (relative activity [RA] = 100%) and Arg-Pro-p-nitroanilide (RA, 130%), was purified to homogeneity from the cell extract of Lactobacillus helveticus CNRZ 32. The enzyme also hydrolyzed Ala-Pro-Gly (RA, 11%) and Ala-Ala-p-nitroanilide (RA, 2%) but was not active on Ala-Leu-Ala, dipeptides, and endopeptidase and carboxypeptidase substrates. The enzyme was purified 145-fold by streptomycin sulfate precipitation, ammonium sulfate fractionation, and a series of column chromatographies on DEAE-cellulose, arginine-Sepharose 4B, and glycyl-prolyl-AH-Sepharose 4B. The purified enzyme appeared as a single band on native polyacrylamide gel and sodium dodecyl sulfate-polyacrylamide gel electrophoreses and had a molecular weight of 72,000. Optima for activity by the purified enzyme were pH 7.0 and 40°C. The enzyme was incubated at 40°C for 15 min with various metal ions. It was activated by Mg2+ (2.5 mM), Ca2+ (0.1 to 2.5 mM), Na+ (10 to 50 mM), and K+ (10 to 50 mM) and was inhibited by Hg2+ (0.1 to 2.5 mM), Cu2+ (0.1 to 2.5 mM), and Zn2+ (0.1 to 2.5 mM). Enzyme activity was partially inhibited by EDTA (1.0 mM, 20 h at 40°C), 1,10-phenanthroline (1.0 mM, 15 min at 40°C), phenylmethylsulfonyl fluoride (1.0 mM), N-ethylmaleimide (1.0 mM), and iodoacetate (1.0 mM). It was completely inhibited by diisopropyl fluorophosphate (1.0 mM, 2 h at 40°C) and p-chloromercuribenzoate (1.0 mM, 15 min at 40°C). The enzyme was not affected by dithioerythritol (1.0 to 10 mM). 相似文献
17.
Mazhar N. Malik Laurie A. Meyers Khalid Iqbal Ashfaq M. Sheikh Lois Scotto Henryk M. Wisniewski 《Life sciences》1981,29(8):795-802
A Ca2+ activated protease(s) capable of hydrolyzing several polypeptides at neutral pH including cytoskeletal proteins, actin, myosin, tubulin and neurofilament triplet was identified in calf brain cortex. The enzyme activity precipitates at 75 mM KCl, pH 6.5 – 7.0 and is inhibited by the sulfhydryl inhibitors, N-ethylmaleimide and para-chloromercuribenzoate and the protease inhibitors, antipain, pepstatin and leupeptin, leupeptin being the most effective. 相似文献
18.
Sensitivity of glutamine synthetase assay by the hydroxamate method can be doubled by replacing ferric chloride with ferric nitrate or ferric perchlorate, each with the appropriate acid. 相似文献
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Nicky Spence Nancy C.L. Rodrigues Polykarpos Angelos Nomikos Khalid Mohammed Yaseen Mansour Abdullah Alshehri 《Journal of musculoskeletal & neuronal interactions》2020,20(4):480
Objectives:The purpose of this study is to establish whether physiotherapists’ ratings are consistent, when using the Action Research Arm Test (ARAT) to score a chronic stroke patient.Methods:This was part of a large project establishing the reliability in chronic stroke. This study used a correlational design comparing the association between physiotherapist scores of the same patient, to establish the ARAT’s inter-rater reliability. The COSMIN checklist was followed to enhance the methodology of the study.Results:Twenty physiotherapists (8 female and 12 male) aged between 25 and 53 years were selected. There were no participant dropouts or withdrawals. The sample size was normally distributed. The physiotherapists appeared representative of the UK physiotherapy population, with the exception of gender. The distribution of scores showed a normal distribution with standard deviation of score of 1.9. The Kendall’s W test showed 0.711 of agreement between the raters. The scores achieved statistical significance showing consistency between physiotherapists’ scores with chronic stroke. Limitations of the study were the use of a small single center convenience sample that may reduce the generalizability of the findings.Conclusions:The ARAT is consistent when scored by physiotherapists in a chronic stroke population. The inter-rater reliability range was (0.70 to 0.90) which is categorized as good. 相似文献