离体子宫平滑肌测定方法的改进

目的:探索离体子宫平滑肌测定方法中,使用增氧泵通气取代混合氧为离体子宫平滑肌供氧的可行性。方法:采用RM-6240BD多道生理信号采集处理系统,观察营养液内通入混合氧、增氧泵通气及无通气对离体子宫平滑肌活动力的影响。结果:与营养液内通入混合氧相比,离体子宫平滑肌的活动力在混合氧组与增氧泵通气组间无统计学差异(P0.05),不通气组的频率和活动力均有统计学差异(P0.05或P0.01)。结论:可以使用增氧泵通气为离体子宫平滑肌供氧,既满足了供氧,同时也可促进营养液流动,使离体子宫与营养液充分接触。     

p38 and Extracellular Signal‐Regulated Kinases Activations have Opposite Effects on Primary‐Cultured Rat Cerebellar Granule Neurons Exposed to Sodium Arsenite

Arsenic is a widespread environmental toxicant in the world and regarded as both a carcinogen and an anticarcinogen. The present study was designed to evaluate roles of mitogen‐activated protein kinases in sodium arsenite‐induced effects on primary‐cultured rat cerebellar granule neurons (CGNs). Results revealed a decreased viability of the cells exposed to sodium arsenite (from 0 to 50 μM) in a dose‐dependent manner. Annexin V‐fluorescein isothiocyanate assay showed that apoptosis was obviously induced by arsenite treatment. High phosphorylation expressions of p38 and extracellular signal‐regulated kinases (ERK1/2), but not of c‐Jun N‐terminal kinases were observed due to arsenite treatment by western blotting analysis. Furthermore, SB203580 (an inhibitor of p38) decreased the percentage of apoptotic cells whereas arsenite‐stimulated toxicity was enhanced by U0126 (an inhibitor of ERK1/2). Taken together, these data suggest that p38 contributes to arsenite‐induced apoptosis of rat CGNs, but ERK1/2 may involve in cell growth and survival.     

Sphingolipid regulation of ezrin,radixin, and moesin proteins family: Implications for cell dynamics

A key but poorly studied domain of sphingolipid functions encompasses endocytosis, exocytosis, cellular trafficking, and cell movement. Recently, the ezrin, radixin and moesin (ERM) family of proteins emerged as novel potent targets regulated by sphingolipids. ERMs are structural proteins linking the actin cytoskeleton to the plasma membrane, also forming a scaffold for signaling pathways that are used for cell proliferation, migration and invasion, and cell division. Opposing functions of the bioactive sphingolipid ceramide and sphingosine-1-phosphate (S1P), contribute to ERM regulation. S1P robustly activates whereas ceramide potently deactivates ERM via phosphorylation/dephosphorylation, respectively. This recent dimension of cytoskeletal regulation by sphingolipids opens up new avenues to target cell dynamics, and provides further understanding of some of the unexplained biological effects mediated by sphingolipids. In addition, these studies are providing novel inroads into defining basic mechanisms of regulation and action of bioactive sphingolipids. This review describes the current understanding of sphingolipid regulation of the cytoskeleton, it also describes the biologies in which ERM proteins have been involved, and finally how these two large fields have started to converge. This article is part of a Special Issue entitled New Frontiers in Sphingolipid Biology.     

Efficacy of some antioxidants supplementation in reducing oxidative stress post sodium tungstate exposure in male wistar rats

This study aimed to evaluate the protective efficacy of some antioxidants against sodium tungstate induced oxidative stress in male wistar rats. Animals were sub-chronically exposed to sodium tungstate (100 ppm in drinking water) for three months except for control group. In the same time, many rats were supplemented orally with different antioxidants (alpha-lipoic acid (ALA), n-acetylcysteine (NAC), quercetin or naringenin (0.30 mM)) for five consecutive days a week for the same mentioned period before. Exposure to sodium tungstate significantly (P < 0.05) inhibit blood δ-aminolevulinic acid dehydratase (ALAD) activity, liver and blood reduced glutathione (GSH) levels and an increase in oxidized glutathione (GSSG) and thiobarbituric acid reactive species (TBARS) levels in tissues. ALA acid and NAC supplementation post sodium tungstate exposure increased GSH and also, was beneficial in the recovery of altered superoxide dismutase and catalase activity, besides, significantly reducing blood and tissue reactive oxygen species and TBARS levels. The results suggest a more pronounced efficacy of ALA acid and NAC supplementation than quercetin or naringenin supplementation post sodium tungstate exposure in preventing induced oxidative stress in rats.     

A highly predictive 3D-QSAR model for binding to the voltage-gated sodium channel: Design of potent new ligands

A comprehensive comparative molecular field analysis (CoMFA) model for the binding of ligands to the neuronal voltage-gated sodium channel was generated based on 67 diverse compounds. Earlier published CoMFA models for this target provided μM ligands, but the improved model described here provided structurally novel compounds with low nM IC₅₀. For example, new compounds 94 and 95 had IC₅₀ values of 129 and 119 nM, respectively.     

Regulation of an alternative sigma factor σI by a partner switching mechanism with an anti-sigma factor PrsI and an anti-anti-sigma factor ArsI in Streptomyces coelicolor A3(2)

Natural transfer of mitochondrial DNA has occurred between three western Palaearctic waterfrog taxa: Pelophylax lessonae, Pelophylax ridibundus and their hybridogenetic hybrid, Pelophylax kl. esculentus. The transfer is asymmetric with most P. kl. esculentus and approximately one third of all central European P. ridibundus having mtDNA derived from P. lessonae (L-mtDNA). We obtained complete nucleotide sequences of multiple mitochondrial genomes (15,376-78 bp without control regions) from all 3 taxa, including a P. ridibundus frog with introgressed L-mtDNA. The gene content and organization of the mitogenomes correspond to those typical of neobatrachians. Divergence between the mtDNAs of P. lessonae and P. ridibundus is high with an uncorrected p-distance of 11.9% across the entire mitogenome. However, the rate of nucleotide substitution depends on the degree of functional constraint with up to 30-fold differences in levels of divergence. In general, mitochondrial genes encoding the translational machinery evolve very slowly, whereas genes encoding polypeptides of the electron transport system, especially the ND genes, evolve rapidly. Only 25 of 211-213 observed amino acid replacements could be classified as radical and are therefore more likely to be exposed to selection. A disproportionately high number of amino acid substitutions has occurred in the ND4, ND4L and cytb genes of the P. lessonae lineage (including 36% of all radical changes). In contrast to the interspecific divergence, nucleotide polymorphism within L- and R-mtDNA is very low: L-mtDNA haplotypes differed on average by only 19 nucleotides, while there was no variation within two mtDNAs derived from P. ridibundus. This is an expected finding considering that we have sampled a post-glacial expansion area. Moreover, the introgressed L-mtDNA on a P. ridibundus background differed from other L-mtDNAs by only a few substitutions, indicative of a very recent introgression event. We discuss our findings in the context of natural selection acting on L-mtDNA and its potential significance in cytonuclear epistasis.     

A case of primary selective hypoaldosteronism carrying three mutations in the aldosterone synthase (Cyp11b2) gene

An infant with a clinical phenotype of early onset hypoaldosteronism has been screened for mutation analysis of the Cyp11b2 gene encoding aldosterone synthase enzyme. We have described a novel nonsense mutation in exon 3 (c.508 C > T) that gave rise to a shorter protein (Q170X) and two known concurrent missense mutations (c.594A > C in exon 3 and c.1157 T > C in exon 7) that led to substitution of glutamic acid for aspartic acid at amino acid position 198 (E198D) and of valine for alanine at amino acid position 386 (V386A). The father, who carried E198D plus V386A mutations, showed a fractional sodium excretion of 1.25% that was unmodified by dietary salt restriction, suggesting a mild haploinsufficiency.     

A novel method for whole blood PCR without pretreatment

PCR is usually performed on purified DNA. However, the extraction of DNA from whole blood is time consuming and involves the risk of contamination at every step. Hence, it is desirable to amplify DNA directly from whole blood. Earlier, investigators tried to achieve this target by either pretreatment of whole blood samples with different agents or by altering the conventional thermal cyclic conditions. This would make the technique cumbersome and time consuming. Here, we describe a simple protocol to amplify DNA directly from whole blood without the need of pretreatment. PCR buffer system was optimized in the laboratory and Apolipoprotein B gene was used as a model for this experiment. 480 bp was the target site for amplification. Fresh whole blood samples were used both from healthy and diseased individuals (coronary artery disease patients). Successful amplification was achieved with 1 μl volume of whole blood and it was comparable to that of genomic DNA. No pretreatment of whole blood samples was required with the optimized buffer system. 3mM concentration of MgCl(2) was observed to be optimal and hence used in the reaction mixture. Amplification was relatively better with this buffer system as compared to that of commercially available PCR buffer. With the present technique, amplicon detection did not require the centrifugation/dilution of the PCR products which further saves time. Successful amplification was achieved in both the healthy and diseased blood samples, indicating the robustness of the technique as changed blood composition and presence of increased inhibitory molecules in the diseased state did not seem to affect the efficacy of the present technique. In conclusion, as compared to the existing protocols for whole blood PCR, the present technique is relatively novel, simple, requires minimal steps and eliminates the need for additional standardizations.