137Cs γ射线诱导人外周血线粒体DNA缺失的时间和剂量-效应关系

目的 研究¹³⁷Cs γ射线诱导的人外周血线粒体DNA 4934 bp和4977 bp缺失的时间和剂量-效应,并探讨其在电离辐射受照者剂量估算中的应用意义。方法 采集5名健康成人外周血进行¹³⁷Cs γ射线离体照射,取其中1份血样给予5 Gy照射后分别培养2、24、48和72 h,另4份血样均经6等分后分别给予0、0.5、1、2、5和10 Gy照射,孵养2 h后采用实时荧光定量PCR方法和凝胶电泳,检测人外周血线粒体DNA 4934 bp(mtDNA 4934 bp)和4977 bp(mtDNA 4977 bp)缺失的表达水平,并用Curve Expert 1.4软件拟合剂量-效应曲线。结果 ¹³⁷Cs γ射线照射离体人血后,诱发的mtDNA 4934 bp 缺失和mtDNA 4977 bp 缺失在照后2 h即升高,mtDNA 4934 bp缺失水平在照后2 h和48 h有相对表达高点(t=10.782和8.966, P<0.05);而mtDNA 4977 bp缺失水平在照后48 h表达最高(t=7.433, P<0.05)。0.5~10 Gy的¹³⁷Cs γ射线照射诱发的mtDNA 4934 bp 缺失(t=2.895~8.105, P<0.05)和mtDNA 4977 bp 缺失(t=3.006~7.715, P<0.05)均随照射剂量增加。其中,mtDNA 4977 bp缺失在相同照射剂量下变化更大,尤其是在10 Gy剂量照射时,二者差异更明显(t=2.919, P<0.05),即对于大剂量照射,mtDNA 4977 bp缺失可能更为灵敏,但是个体差异较mtDNA 4934 bp缺失大。拟合的剂量-效应曲线回归方程分别为Ŷ₁=1.178+0.1219D(R²=0.9269, mtDNA 4934 bp缺失)和Ŷ₂=1.2578+0.1933D(R²=0.9016, mtDNA 4977 bp缺失)。结论 ¹³⁷Cs γ射线诱发的线粒体DNA片段缺失与辐射剂量有良好的数学回归关系,有可能为照射后生物剂量快速估算和预后评估提供依据。     

Increased prevalence of vitiligo, but no evidence of premature ageing, in the skin of patients with bp 3243 mutation in mitochondrial DNA in the mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes syndrome (MELAS)

The MELAS syndrome (mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes) belongs to the category of mitochondrial disorders. The most common molecular aetiology of the syndrome is a mutation at base pair (bp) 3243 in the mitochondrial genome (mtDNA). The phenotype is varied and, apart from central nervous system involvement, the patients with this mutation may present with neurosensory hearing loss, diabetes mellitus and cardiomyopathy. These phenotypes suggest that organs dependent on aerobic metabolism suffer most. We investigated the possible clinical and physiological manifestations of impaired energy metabolism in the skin of 28 patients with the bp 3243 mutation in mtDNA. Non-invasive sonography and laser Doppler flowmetry were used to measure skin thickness and the blood flow of the skin. Skin collagen synthesis was assayed from suction blister fluid. Evaporimetry was used to assess the re-epithelialization rate of suction blister wounds. Histochemistry and immunohistochemistry were used to evaluate the melanocytes and pigment in the skin. Vitiligo was found in three of the 28 patients (11%), which was markedly more than in the general population. Histological findings showed an absence of pigment, but an apparently normal distribution of melanocytes in the dermoepidermal junction. Seborrhoeic eczema and atopy were also somewhat more frequent. No features of premature ageing, such as a marked decrease in skin thickness, blood flow, collagen synthesis or re-epithelialization rate, were demonstrated.     

HLA‐G 14‐bp polymorphism: a possible marker of systemic treatment response in psoriasis vulgaris? Preliminary results of a retrospective study

Human leukocyte antigen‐G (HLA‐G) is a nonclassical HLA class I molecule that exerts an immunosuppressive function. A 14‐base pair (bp) sequence insertion/deletion (INS/DEL) polymorphism in the exon 8 at the 3′ untranslated region (UTR) modifies mRNA stability and protein production and has been shown to concur with efficacy of pharmacological treatments in immune‐mediated conditions. The aim of this study was to assess for the first time the correlation between HLA‐G 14‐bp INS/DEL polymorphism with the response to systemic therapy in psoriatic patients. We retrospectively analyzed the HLA‐G 14‐bp INS/DEL polymorphism of HLA‐G gene in patients with moderate to severe plaque psoriasis: 21 treated with acitretin, 16 with cyclosporine, 11 with anti‐TNF‐α. Patients who reached PASI 75 at weeks 10–16 were considered responders. Among patients treated with acitretin, we observed a significantly increased frequency of the HLA‐G DEL allele and of the DEL/DEL genotype in responder patients when compared with nonresponders. An association between HLA‐G genotype and response to cyclosporine and biologics was not found. The significant association between HLA‐G 14‐bp DEL allele and 14‐bp DEL/DEL genotype and acitretin clinical outcome may suggest an advantage of this allele and propose this HLA‐G polymorphism as a potential marker of response to acitretin in psoriatic patients.     

Association of MB-COMT polymorphisms with schizophrenia-susceptibility and symptom severity in an African cohort

The catechol-O-methyltransferase (COMT) gene is an attractive schizophrenia candidate gene, encoding a catabolic dopamine enzyme. The enzyme exists as two distinct isoforms, with the membrane bound enzyme (i.e. MB-COMT) being predominantly expressed in the brain. Since African populations remain underrepresented in genetic/genomic research, we performed an association study to determine whether MB-COMT genetic variants are associated with schizophrenia-susceptibility and symptom severity in the South African Xhosa population. Fourteen candidate polymorphisms were selected by means of a literature search and in silico analyses and were subsequently genotyped in a cohort of 238 Xhosa schizophrenia patients and 240 healthy Xhosa controls. Genetic association was tested with schizophrenia-susceptibility as well as symptom severity within the patient group. Polymorphisms of interest were also analysed using functional assays. Two SNPs, rs2020917 (OR=0.54, 95% CI 0.37-0.79; P=0.0011) and rs737865 (OR=0.52, 95% CI 0.36-0.74; P=0.0002), in the P2 promoter region were significantly associated with schizophrenia as well as an increase (increase=11.2%, 95% CI 3.7%-19.2%; P=0.0031) in reporter gene expression. The minor alleles of these SNPs were underrepresented in the schizophrenia cohort, indicating a possible protective effect. The P2 region also formed part of a haplotype found to be associated with the severity of the negative symptoms of the disorder. The data generated by this study indicate that genetic variation of MB-COMT could be associated with schizophrenia and negative symptom severity in the Xhosa population and may therefore be one of the genomic loci contributing towards the disorder in the South African community. Future large-scale studies in other African schizophrenia populations are required to further elucidate the significance of these findings.     

The association of 5-HTR2A-1438A/G, COMTVal158Met, MAOA-LPR, DATVNTR and 5-HTTVNTR gene polymorphisms and antisocial personality disorder in male heroin-dependent Chinese subjects

Objective

To explore the association between the 5-HTR2A-1438A/G, COMTVal158Met, MAOA-LPR, DATVNTR and 5-HTTVNTR polymorphisms with comorbidity of antisocial personality disorder in male heroin-dependent patients.

Subjects and methods

In case control study, we compared the polymorphic distributions of 5-HTR2A-1438A/G, COMTVal158Met, MAOA-LPR, DATVNTR and 5-HTTVNTR in 588 male heroin-dependent patients (including 311 patients with antisocial personality disorder and 277 patients without antisocial personality disorder) and 194 normal males by genotypes, alleles, and interaction between genes.

Results

Between male heroin-dependent patients with antisocial personality disorder and normal males, and between male heroin-dependent patients with and without antisocial personality disorder, the distributions of 5-HTTVNTR polymorphic genotypes and alleles were in statistical significance. Individuals carrying 10R allele were in higher risk of the comorbidity of antisocial personality disorder and heroin dependence. By MDR analyses, the interaction between 5-HTTVNTR and DATVNTR was close to statistical significance in predicting the risk of antisocial personality disorder in male heroin dependent patients. In male heroin dependent patients, individuals carrying 5-HTTVNTR 10R allele or/and DATVNTR 9R allele were in higher risks of co-occurring antisocial personality disorder, while individuals with 5-HTTVNTR 12R/12R and DATVNTR 10R/10R genotypes together were in lower risks of antisocial personality disorder.

Conclusion

5-HTTVNTR, and the interaction between 5-HTTVNTR and DATVNTR may be associated with the comorbidity of antisocial personality disorder in male heroin-dependent patients.     

A new method for detection of pandemic influenza virus using High Resolution Melting analysis of the neuraminidase gene

Diagnostic methods based upon exclusive detection of haemagglutinin do not detect sequence variation in other gene segments of the Influenza A virus. A complementary approach is described based upon high-resolution melting curve analysis of the neuraminidase gene, an approach with the potential ability to detect small changes in the neuraminidase sequence without the need for specific probes.     

Molecular evidence of ‘Siisa form’, a new genotype related to Onchocerca ochengi in cattle from North Cameroon

Onchocerca ochengi, a filarial nematode parasite from African Zebu cattle is considered to be the closest relative of Onchocerca volvulus, the causative agent of river blindness. Both Onchocerca species share the vector, black flies of the Simulium damnosum complex. Correct identification of their infective third-stage larvae in man-biting vectors is crucial to distinguish the transmission of human or animal parasites. In order to identify different closely related Onchocerca species we surveyed the sequences from the three mitochondrial loci 12S rRNA, 16S rRNA and coxI in both adult worms isolated from Onchocerca-induced nodules in cattle and infective third stage larvae isolated from vector flies from North Cameroon. Two distinct groups of mitochondrial haplotypes were found in cattle as well as in flies. One of them has been formerly mentioned in the literature as Onchocerca sp. ‘Siisa’, a filaria isolated from the vector S. damnosum sensu lato in Uganda with hitherto unknown host. Both variants are found sympatric, also in the same nodule of the animal host and in the vector. In the flies we also found the mitochondrial haplotype that had been described for O. volvulus which is about equally different from the two previously mentioned ones as they are from each other. These results suggest a higher genetic diversification of Onchocerca ochengi than previously reported.     

Thymidylate Synthase Polymorphisms and Risk of Lung Cancer among the Jordanian Population: a Case Control Study

Background: Thymidylate synthase (TS) catalyzes the methylation of deoxyuridylate to deoxythymidylate and is involved in DNA methylation, synthesis and repair. Two common polymorphisms have been reported, tandem repeats in the promoter-enhancer region (TSER), and 6bp ins/del in the 5 UTR, that are implicated in a number of human diseases, including cancer. The association between the two polymorphisms in risk for lung cancer (LC) was here investigated in the Jordanian population. Materials and Methods: An age, gender, and smoking-matched case-control study involving 84 lung cancer cases and 71 controls was conducted. The polymerase chain reaction/restriction fragment length polymorphism (PCR-RFLP) technique was used to detect the polymorphism of interest. Results: Individuals bearing the ins/ins genotype were 2.5 times more likely to have lung cancer [(95%CI: 0.98-6.37), p=0.051]. Individuals who were less than or equal to 57 years and carrying ins/ins genotype were 4.6 times more susceptible to lung cancer [OR<57 vs >57years: 4.6 (95%CI: 0.93-22.5), p=0.059)]. Genotypes and alleles of TSER were distributed similarly between cases and controls. Weak linkage disequilibrium existed between the two loci of interest (Lewontin’s coefficient [D’]) (LC: D’ =0.03, r2: 0. 001, p= 0.8; Controls: D’ =0.29, r2: 0.08, p=0.02). Carriers of the “3 tandem repeats_insertion” haplotype (3R_ins) were 2 times more likely to have lung cancer [2 (95%CI: 1.13-3.48), p=0.061]. Conclusions: Genetic polymorphism of TS at 3` UTR and its haplotype analysis may modulate the risk of lung cancer in Jordanians. The 6bp ins/del polymorphism of TS at 3 `UTR is more informative than TSER polymorphism in predicting increased risk.