Reduction of apoptosis through the mitochondrial pathway by the administration of acetyl-L-carnitine to mouse fibroblasts in culture

It is shown in literature that stress, such as deprivation of trophic factors and hypoxia, induces apoptosis in cultured cells and in tissues. In light of these results, we explored the possibility of protecting cells from programmed death by improving the metabolism of the mitochondrion. To this end, acetyl-L-carnitine was administered at various concentrations under conditions of serum deprivation. The choice of this drug was based on the accepted notion that acetyl-L-carnitine is able to stabilize mitochondrial membranes and to increase the supply of energy to the organelle. The results presented here indicate that the drug protects cells from apoptotic death: this is demonstrated by a lower positivity to the TUNEL reaction and by a strong reduction of the apoptotic DNA ladder in serum-deprived cells. The involvement of the mitochondrial apoptotic pathway was assessed by cytochrome C release and immunoreactivity to caspase 3. Moreover, acetyl-L-carnitine stimulates cell proliferation.     

Association and linkage analysis of RGS4 polymorphisms with schizophrenia and bipolar disorder in Brazil

Linkage and association studies in five independently ascertained samples have suggested that polymorphisms of the regulator of G-protein signaling 4 (RGS4) may confer risk for schizophrenia (SCZ). Suggestive evidence for association with bipolar disorder (BD) has also been presented. However, the associated alleles and haplotypes have differed among the samples. Data from other independent samples may clarify the putative associations. Hence, we investigated an independent, ethnically diverse Brazilian population comprising patients with SCZ (n=271) or BD1 (n=306), who were contrasted with 576 community-based controls. Parents of 49 SCZ cases and 44 BD cases were available for transmission disequilibrium tests (TDTs). Four RGS4 single-nucleotide polymorphisms (SNPs) 1, 4, 7 and 18 putatively associated with SCZ were investigated. In the SCZ samples, significant case-control differences were not observed for individual SNPs or haplotypes, though the TDT suggested transmission distortion similar to that observed in the initial report. For the BD sample, case-control comparisons revealed no significant differences for individual SNPs, but an omnibus test suggested differences in the overall distribution of haplotypes bearing all four SNPs (SNP-EM Omnibus likelihood ratio test; P=0.003). The TDT revealed over-transmission of allele A at SNP7 (P=0.016), as well as haplotypes incorporating this allele. However, global tests incorporating all haplotypes yielded only suggestive trends for association (P=0.19). In conclusion, association with SCZ was not detected in the present analyses. The failure to detect an association may be related to inadequate power or to confounds related to ethnic admixture. Suggestive associations with BD detected here require further investigation in a larger sample.     

在中国汉族人群中,以家系传递分析肿瘤坏死因子a-308A/G单核苷酸多态性与抽动秽语综合征

目的：探讨在中国汉族人群中,肿瘤坏死因子a（TNF-alpha,TNF-a）基因启动子区-308A/G单核苷酸多态性与抽动秽语综合征（Tourette syndrome,TS）的遗传易感性。方法：91例TS患者及其父母组成的核心家系成员经聚合酶链式反应-限制性片段长度多态性（polymerase chain reaction-restriction fragment lengthpolymor phism,PCR-RFLP）方法进行基因分型,评估所有研究对象的TNF-a-308A/G位点的等位基因频率和基因型频率的分布,进行传递不平衡检验（transmission disequilibrium test,TDT）,单体型相对风险（haplotype-based haplotyp erelativerisk,HHRR）,单体型风险（haplotype relative riskHRR）的研究。结果：TS患者及其父母的等位基因分布经Hardy-Weinberg（H-W）平衡检验显示符合遗传平衡法则。（x2〈3.84;P〉0.05）TDT、HHRR和HRR研究结果显示该多态性位点的等位基因频率和基因型频率均不存在传递不平衡。结论：我们的数据表明肿瘤坏死因子a启动子区-308A/G单核苷酸多态性位点不是中国汉族人群TS的易感基因位点。     

在中国汉族人群中，以家系传递分析肿瘤坏死因子a-308A/G单核苷酸多 态性与抽动秽语综合征

目的:探讨在中国汉族人群中,肿瘤坏死因子a(TNF-alpha,TNF-a)基因启动子区-308A/G单核苷酸多态性与抽动秽语综合征(Tourette syndrome,TS)的遗传易感性。方法:91例TS患者及其父母组成的核心家系成员经聚合酶链式反应-限制性片段长度多态性(polymerase chain reaction-restriction fragment lengthpolymor phism,PCR-RFLP)方法进行基因分型,评估所有研究对象的TNF-a-308A/G位点的等位基因频率和基因型频率的分布,进行传递不平衡检验(transmission disequilibrium test,TDT),单体型相对风险(haplotype-based haplotyp erelativerisk,HHRR),单体型风险(haplotype relative riskHRR)的研究。结果:TS患者及其父母的等位基因分布经Hardy-Weinberg(H-W)平衡检验显示符合遗传平衡法则。(x2<3.84;P>0.05)TDT、HHRR和HRR研究结果显示该多态性位点的等位基因频率和基因型频率均不存在传递不平衡。结论:我们的数据表明肿瘤坏死因子a启动子区-308A/G单核苷酸多态性位点不是中国汉族人群TS的易感基因位点。     

Structural basis of mercury- and zinc-conjugated complexes as SARS-CoV 3C-like protease inhibitors

Five active metal-conjugated inhibitors (PMA, TDT, EPDTC, JMF1586 and JMF1600) bound with the 3C-like protease of severe acute respiratory syndrome (SARS)-associated coronavirus were analyzed crystallographically. The complex structures reveal two major inhibition modes: Hg(2+)-PMA is coordinated to C(44), M(49) and Y(54) with a square planar geometry at the S3 pocket, whereas each Zn(2+) of the four zinc-inhibitors is tetrahedrally coordinated to the H(41)-C(145) catalytic dyad. For anti-SARS drug design, this Zn(2+)-centered coordination pattern would serve as a starting platform for inhibitor optimization.     

Testing and estimating gene-environment interactions in family-based association studies

Summary .   We propose robust and efficient tests and estimators for gene–environment/gene–drug interactions in family-based association studies in which haplotypes, dichotomous/quantitative phenotypes, and complex exposure/treatment variables are analyzed. Using causal inference methodology, we show that the tests and estimators are robust against unmeasured confounding due to population admixture and stratification, provided that Mendel's law of segregation holds and that the considered exposure/treatment variable is not affected by the candidate gene under study. We illustrate the practical relevance of our approach by an application to a chronic obstructive pulmonary disease study. The data analysis suggests a gene–environment interaction between a single nucleotide polymorphism in the Serpine2 gene and smoking status/pack-years of smoking. Simulation studies show that the proposed methodology is sufficiently powered for realistic sample sizes and that it provides valid tests and effect size estimators in the presence of admixture and stratification.     

Alternative S2 hinge regions of the myosin rod differentially affect muscle function, myofibril dimensions and myosin tail length

Muscle myosin heavy chain (MHC) rod domains intertwine to form alpha-helical coiled-coil dimers; these subsequently multimerize into thick filaments via electrostatic interactions. The subfragment 2/light meromyosin "hinge" region of the MHC rod, located in the C-terminal third of heavy meromyosin, may form a less stable coiled-coil than flanking regions. Partial "melting" of this region has been proposed to result in a helix to random-coil transition. A portion of the Drosophila melanogaster MHC hinge is encoded by mutually exclusive alternative exons 15a and 15b, the use of which correlates with fast (hinge A) or slow (hinge B) muscle physiological properties. To test the functional significance of alternative hinge regions, we constructed transgenic fly lines in which fast muscle isovariant hinge A was switched for slow muscle hinge B in the MHC isoforms of indirect flight and jump muscles. Substitution of the slow muscle hinge B impaired flight ability, increased sarcomere lengths by approximately 13% and resulted in minor disruption to indirect flight muscle sarcomeric structure compared with a transgenic control. With age, residual flight ability decreased rapidly and myofibrils developed peripheral defects. Computational analysis indicates that hinge B has a greater coiled-coil propensity and thus reduced flexibility compared to hinge A. Intriguingly, the MHC rod with hinge B was approximately 5 nm longer than myosin with hinge A, consistent with the more rigid coiled-coil conformation predicted for hinge B. Our study demonstrates that hinge B cannot functionally substitute for hinge A in fast muscle types, likely as a result of differences in the molecular structure of the rod, subtle changes in myofibril structure and decreased ability to maintain sarcomere structure in indirect flight muscle myofibrils. Thus, alternative hinges are important in dictating the distinct functional properties of myosin isoforms and the muscles in which they are expressed.     

Ewing's sarcoma: Analysis of single nucleotide polymorphism in the EWS gene

We aimed to investigate single nucleotide polymorphisms (SNPs) in the EWS gene breaking region in order to analyze Ewing's sarcoma susceptibility. The SNPs were investigated in a healthy subject population and in Ewing's sarcoma patients from Southern Brazil. Genotyping was performed by TaqMan® assay for allelic discrimination using Real-Time PCR. The analysis of incidence of SNPs or different SNP-arrangements revealed a higher presence of homozygote TT-rs4820804 in Ewing's sarcoma patients (p = 0.02; Chi Square Test). About 300 bp from the rs4820804 SNP lies a palindromic hexamer (5′-GCTAGC-3′) and three nucleotides (GTC), which were previously identified to be in close vicinity of the breakpoint junction in both EWS and FLI1 genes. This DNA segment surrounding the rs4820804 SNP is likely to indicate a breakpoint region. If the T-rs4820804 allele predisposes a DNA fragment to breakage, homozygotes (TT-rs4820804) would have double the chance of having a chromosome break, increasing the chances for a translocation to occur. In conclusion, the TT-rs4820804 EWS genotype can be associated with Ewing's sarcoma and the SNP rs4820804 can be a candidate marker to understand Ewing's sarcoma susceptibility.