Gender-dependent variations in systemic biomarkers of oxidative protein,DNA, and lipid damage in aged rats

Introduction.?The effect of aging on plasma-protein, lipid and DNA oxidation is well documented. However, none of the studies specify the effect of gender. The purpose of this study is to clarify the ambiguity raised in preliminary reports as to gender dependency of oxidative damage in plasma.

Methods.?In the current study, we investigated the relation between 8-hydroxy-2′-deoxyguanosine levels (8-OHdG), which is a measure of DNA oxidation and protein oxidation parameters such as protein carbonyl (PCO), total thiol (T-SH), and advanced oxidation protein products (AOPP). Our study also covered other oxidative stress parameters, such as lipid hydroperoxides (LHP), malondialdehyde (MDA), erythrocyte glutathione (GSH), superoxide dismutase (Cu-Zn SOD) and the catalase (CAT) activity in plasma of the male and female aged rats.

Results.?8-OHdG and MDA levels in male rats were significantly higher than those in the female group (p?<?0.01 for both parameters). T-SH levels were found to be higher in female rats than in the male (p?<?0.05). Plasma Cu-Zn SOD activities of male rats were significantly higher compared with those of the female rats (p?<?0.05). On the other hand, PCO, AOPP, LHP, GSH levels, and CAT activity were not found to be different between genders.

Conclusions.?We suggest that increased T-SH levels found in female rats may point to an adaptive reaction to oxidative damage, reflecting 8-OHdG and MDA overproduction. We are of the conviction that the increased 8-OHdG and MDA that we have determined in aged male rats may be a risk factor in the extent of oxidation in plasma.     

Interpreting forensic DNA mixtures: allowing for uncertainty in population substructure and dependence

We consider the assessment of deoxyribonucleic acid (DNA) profiles from biological samples containing a mixture of DNA from more than one person. The problem has been investigated in the context of likelihood ratios by Weir and co-workers under the assumption of independent alleles in DNA profiles. However, uncertainty about independence may arise from various factors such as population substructure and relatedness. This issue has received considerable attention in recent years. Ignoring this uncertainty may seriously overstate the strength of the evidence and therefore disadvantage innocent suspects. Taking this uncertainty into account, we develop a general formula for calculating the match probabilities of DNA profiles. Thus, we extend the result derived by Weir and co-workers to the dependence situation, which is often more to the benefit of the defendant in comparison with the simple product rule result based on an independence assumption. The effect of dependence of alleles on likelihood ratio estimates can be seen in the analysis of two real data sets.     

Limiting distribution of the number of clumps of palindromes in DNA

An important aspect in the analysis of long DNA sequences is to identify whether palindromes are over- or under-represented. The essential step in that direction is the analysis of the limiting distribution of the number of clumps of palindromes where clump is defined as the overlapping occurrence of palindromes. Using the Chen–Stein method, it is shown in this paper that the limiting distribution, under suitable conditions and a type of heterogeneous sequence, is the Poisson distribution. Moreover, error bounds and the rate of convergence are derived in terms of total variation distance between two probability distributions.     

Unresolved issues in the forensic use of DNA profiling

The enormous amount of genetic diversity in humans allows for a powerful form of individual identification. This “DNA profiling”; is based on the fact that sites within the human genome have variable numbers of tandem repeats (VNTRs) and has been hailed in forensic sciences as the greatest discovery since fingerprinting. The techniques involved are virtually the same as those used in all molecular biology laboratories. A major difference however is that in forensic science DNA samples can be less than ideal in both quality and quantity. Furthermore, in basic molecular biology the origin of the sample is known while in forensic testing it is not. Thus, the challenge is to reconcile a “match”; between a crime scene DNA sample and one from a suspect(s). Presently, a debate exists regarding the use of the unmodified product rule versus a more conservative ceiling principle approach to calculate the probability of a coincidentally matching DNA profiles. The latter was endorsed in a recently published report by the prestigious National Research Council but has not received widespread support from testing laboratories. Further exacerbating the debate over how much weight should be attached to DNA profile evidence is a lack of widely accepted standards for forensic laboratories especially in the areas of proficiency testing, publication of error rates and laboratory personnel certification.     

Teaching about science

Science is one of the most exciting frontiers of human endeavor and yet is often poorly understood. In this article I argue that improved education of both our children and our adults is key for the future. It is incumbent on all scientists to help educate our citizenry. In addition to the traditional methods we should make better use of television for this purpose. I strongly advocate permeating regular news programs with science news and education.     

MP-120工作站批量提取法医样本DNA

本文运用MP-120自动化DNA提取仪对72份血斑检材进行DNA提取扩增,荧光检测信号均值在200-3000RFU之间,表明所建立的MP-120工作操作程序在血斑的批量提取方面具有较高的成功率、稳定性和均一性,适用于法医DNA数据库的建立和案件中血斑样本的批量提取。     

原位杂交中鲑鱼精DNA处理方法探究

采用机械打断/沸水浴和超声波处理两种方法对原位杂交中的封闭DNA——鲑鱼精DNA进行了断裂处理。分别探讨了不同的吹打次数、煮沸时间和超声波处理时间对鲑鱼精DNA片段大小的影响,并且对机械打断/沸水浴和超声波处理两种方法结果进行了比较分析。研究结果表明在煮沸时间20min时,吹打次数可根据所需原位杂交片段大小进行调整;超声波适宜打断时间为20min。     

Uncertainties in the CIIT Model for Formaldehyde-Induced Carcinogenicity in the Rat: A Limited Sensitivity Analysis–I

Scientists at the CIIT Centers for Health Research (Conolly et al., 2000, 2003; Kimbell et al., 2001a, 2001b) developed a two-stage clonal expansion model of formaldehyde-induced nasal cancers in the F344 rat that made extensive use of mechanistic information. An inference of their modeling approach was that formaldehyde-induced tumorigenicity could be optimally explained without the role of formaldehyde's mutagenic action. In this article, we examine the strength of this result and modify select features to examine the sensitivity of the predicted dose response to select assumptions. We implement solutions to the two-stage cancer model that are valid for nonhomogeneous models (i.e., models with time-dependent parameters), thus accounting for time dependence in variables. In this reimplementation, we examine the sensitivity of model predictions to pooling historical and concurrent control data, and to lumping sacrificed animals in which tumors were discovered incidentally with those in which death was caused by the tumors. We found the CIIT model results were not significantly altered with the nonhomogeneous solutions. Dose-response predictions below the range of exposures where tumors occurred in the bioassays were highly sensitive to the choice of control data. In the range of exposures where tumors were observed, the model attributed up to 74% of the added tumor probability to formaldehyde's mutagenic action when our reanalysis restricted the use of the National Toxicology Program (NTP) historical control data to only those obtained from inhalation exposures. Model results were insensitive to hourly or daily temporal variations in DNA protein cross-link (DPX) concentration, a surrogate for the dose-metric linked to formaldehyde-induced mutations, prompting us to utilize weekly averages for this quantity. Various other biological and mathematical uncertainties in the model have been retained unmodified in this analysis. These include model specification of initiated cell division and death rates, and uncertainty and variability in the dose response for cell replication rates, issues that will be considered in a future paper.     

菊花DNA提纯方法的优化

菊花（Chrysanthemum morifolium)组织内含有较多酚类化合物和多类物质，抽提后获得高质量的基因组DNA有一定难度。以6个菊花品种为试材，利用碱裂解法、SDS法、CTAB法、改良SDS法提取DNA后，根据外观、琼脂糖凝胶电泳检测、A260／A280比值的测定。DNA产量等。比较后的优化结果表明：用改良SDS法提取的菊花基因组DNA，无论在纯度上，还是在完整性上都比其他3种方法要好。     

DNA疫苗技术

随着生物技术的发展,DNA疫苗的研究也进展迅速.DNA疫苗就是将重组的带有外源的抗原基因的质粒或病毒DNA直接注射到动物体内,从而使外源基因在活体内表达,产生的相应的抗原激活机体的免疫系统,引起免疫反应.DNA疫苗多价疫苗相对于一二代疫苗具有更加安全、稳定、可同时诱导广泛的体液免疫和细胞免疫应答及不受母源抗体的影响等一系列优点.随着对DNA疫苗研究的不断进步,DNA疫苗在21世纪第三代疫苗免疫预防方面将会发挥越来越重要的作用.本文着重介绍DNA疫苗的进展与动态.