人外周血白细胞端粒DNA长度与年龄的定量关系

目的探讨人外周血白细胞端粒DNA长度变化规律及其与年龄的关系,为法医学推断年龄提供理论依据。方法抽取西藏那曲地区0~81岁健康人外周血样本105例,其中男性53例,女性52例,采用Southern杂交法检测其端粒限制性片断平均长度。各年龄组性别差异作t检验,端粒长度与年龄的关系作相关及回归分析。结果人外周血白细胞端粒长度随年龄增长逐渐缩短,且存在性别差异;得到推断年龄回归方程:Y=-16.539X+236.287±9.832。结论人外周血白细胞端粒DNA长度与年龄存在明显相关性,为法医学在分子水平上推断个体年龄提供了可能。     

线粒体DNA和端粒与年龄相关性的研究进展

用DNA技术从分子水平上推断年龄,已成为法医学和人类学研究领域的新热点。目前用于年龄推断研究的DNA标记主要是线粒体和端粒。本文从线粒体DNA和端粒的概念、线粒体DNA的缺失和突变、端粒长度变化与年龄的相关性等方面对该领域的研究进展进行了综述。旨在为法医实践及进一步的研究提供新的方法和思路。     

端粒DNA在法医学年龄推断中的应用

法医学中年龄推断的常用方法是对齿龄和骨龄进行推断,但这二种方法都受地理环境、营养状况、生活习惯、民族等因素的影响,尤其对成年人而言准确性会下降。随着对端粒研究的不断深入,已证实端粒DNA长度可反映细胞的分裂程度,代表细胞的生长寿命并与供体年龄有负相关性,因此测定端粒DNA长度有望成为法医学推断年龄有价值的新方法。     

端粒DNA长度检测方法

<正> 端粒(Telomeres)位于染色体末端,由高度重复的DNA序列(人类为TTAGGG)和结合蛋白所构成,保护染色体免遭熔合、重组和降解。端粒DNA长度的改变与衰老、肿瘤发生,以及DNA修复相关联[1,2]。近些年来,学者们发现体细胞端粒DNA长度随年龄或有丝分裂次数的增加而逐渐缩短[3-5]。 年龄鉴定是法医学检验的重要内容,准确的年龄资料可以为刑事案件的侦破提供重要的信息。目前尚无法通过斑迹、软组织等检材的检验来推断个体的年龄。端粒与年龄关系的研究提示:选择合适的人群和组织,检测端粒DNA长度和端粒DNA量的变化,可以发现端粒DNA的变化与年龄的关系,从而推断人的年龄。     

不同年龄组白细胞端粒DNA长度变化研究

目的探讨人外周血白细胞端粒DNA随年龄变化的规律。方法选取123例不同年龄健康人外周血样本,采用非同位素探针标记的SouthernBlot方法检测了端粒DNA限制性酶切片段(Telomericre鄄strictedfragment,TRF)长度的变化。结果对这123例样本就性别组成进行χ2检验,得出P>0.05,说明这123例样品性别对TRF的差异不显著。123例外周血白细胞端粒TRF平均长度随年龄增长而逐渐缩短,且TRF随年龄缩短的速度是不均一的,人外周血白细胞染色体端粒DNA长度可能在5岁左右存在缩短加剧现象。对0～14岁、15～64岁及≥65岁三组进行方差分析(SNK检验),显示有显著性差异(P<0.01)。结论不同年龄组人外周血白细胞端粒DNA长度具有显著差异且变化速率不同,该研究结果为通过端粒DNA长度推断个体年龄提供了可能。     

人外周血白细胞端粒DNA长度变化与性别的关系

目的 探讨人外周血白细胞端粒DNA长度变化与性别的关系。方法 选取123例不同年龄健康人外周血样本，其中男性63例，女性60例，酚氯仿法抽提人基因组DNA，采用地高辛标记探针，通过Southern Blot方法检测端粒DNA限制性酶切片段(TRF)长度的变化。结果 123例外周血白细胞端粒TRF平均长度随年龄增长而逐渐缩短，TRF随年龄缩短的速度是不均一的，且呈现出性别差异。结论 人外周血白细胞端粒DNA长度随年龄缩短的变化速率具有性别差异，通过端粒DNA长度推断个体年龄需考虑到性别因素。     

人DNA指纹检测的初步研究

根据随机探针检测DNA限制片段长度多态性的原理和人与鼠的髓鞘硷性蛋白(MBP)基因cDNA有90％以上同源序列的事实,我们选用rMBP-cDNA 3'端非表达区高度重复顺序的0.81kb片段作探针,检测用HaeⅢ酶解的人DNA限制性片段结果可以分解出22条谱带,受检的30例无血缘关系的个体之间,没有两个人的谱带是完全相同的,显示出此方法的高度特异性。本文还比较了若干DNA片段作探针和几种限制性内切酶检测人DNA指纹的结果。     

PCR-RFLP法分析北方汉族人群HLA-B基因多态性

目的建立以PCR-RFLP法分析HLA-B基因多态性的方法,并对105名北方汉族人群酶切片段类型、频率进行调查,为其法医学应用奠定基础。方法酚/氯仿抽提法抽提样本DNA;PCR扩增HLA-B基因的外显子2,3;NlaIII酶切PCR产物;聚丙烯酰胺凝胶电泳和银染技术检测酶切结果;DNA测序确认酶切位点。结果HLA-B特异性扩增片段长度为943bp,以NlaIII酶进行酶切时在北方汉族人群中获得了14条片段,20种谱带类型,观察到了6个酶切位点。结论仅应用一种内切酶对HLA-B基因进行PCR-RFLP分析即可获得多条片段,多态信息含量大大提高,该法可以应用于法医学亲子鉴定和个人识别等。     

激光捕获显微分离技术在DNA检验中的应用研究

目的建立一套显微细胞捕获技术用于法医学生物检材DNA检验方法。方法使用VeritasTM LCM激光捕获仪,采用紫外加红外的捕获方式,对框架覆膜玻片上经苏木素染色口腔上皮细胞进行捕获,采用改良硅珠法提取细胞DNA,使用Identifiler TM试剂盒在5μL体系中进行PCR扩增。结果成功获得20个口腔上皮细胞的13个以上完整STR基因座分型谱带。结论本研究建立的方法适合法医学生物检材制成的染色涂片上细胞的DNA检验。     

DNA甲基化标记检测方法及其法医学应用

DNA甲基化是重要的表观遗传修饰,主要在转录水平上调控基因的表达。DNA甲基化在人类基因组中含量丰富、分布广泛;甲基化谱有时空特异性、细胞特异性和亲源特异性。新近研究表明DNA甲基化在组织体液鉴定、同卵双生子鉴定、年龄推断、性别推断和亲子鉴定等方面具有一定的应用价值,有望成为一种新的法医学遗传标记。本文就DNA甲基化检测方法的研究进展及法医学应用进行综述,以期为法医学实践提供参考。     

Estimating age of humans based on telomere shortening

To estimate age using DNA based on telomere shortening, we determined the terminal restriction fragment (TRF) length, as telomere length, using Southern blot analysis of peripheral human blood and blood stains. All blood stains had been stored at room temperature for 5 months. The average TRF length clearly showed a tendency to shortening with aging. The formula for age estimation was based on a correlation between average TRF length and age of the subjects. The estimated age calculated from TRF length widely depends on environmental and genetic factors. However, as long as the DNA is well preserved, use of our method is feasible regardless of age of the subject and can give a rough estimation of age of subjects in forensic samples that carry no morphological information.     

用chelex-100提取骨骼DNA的研究

建立了应用chelex-100加蛋白酶K提取骨骼DNA的方法,并对1～30年31例骨骼进行了实验.该方法操作简单、快速、重复性好,灵敏度以及阳性率高,适用于法医学鉴定.     

Digoxin, magnesium, and potassium levels in a forensic autopsy material of sudden death from ischemic heart disease

In 91 cases where the cause of death was heart disease, digoxin, Mg and K concentrations in serum and ventricular myocardium were measured post mortem. Forty per cent were positive for digoxin in both serum and myocardium. The mean serum level was 5.1 +/- 2.4 nmol/l and the mean myocardial level was 42.6 +/- 27.5 ng/g. Correlation could be established between serum and myocardial concentrations of digoxin. There were statistically significant differences in serum as well as in myocardial digoxin levels in persons on 0.13 mg and 0.25 mg per day, respectively. Myocardial levels of Mg and K were low as generally found in persons with ischemic heart disease. There was no correlation between these levels and myocardial digoxin concentrations. Caution must be exercised in the assessment of digoxin results from cadaver samples because of the postmortem rise of digoxin serum concentrations. Considering this fact, the results still indicate that the prevalence of toxic digoxin concentrations might be more common than previously thought.     

Old and very old adults as witnesses: event memory and metamemory

Older people constitute an important category of eyewitnesses. Episodic memory performance in older persons is poorer than in younger adults, but little research has been made on older persons’ metacognitive judgments. Since more persons of advanced age will likely be called upon as witnesses in coming years, it is critical to characterize this population’s metacognitive abilities. We compared event memory metacognition in old adults (66-year-old, n = 74) to very old adults (87 or 90 years old, n = 55). Participants were tested on their memory of a film, using questions with two answer alternatives and the confidence in their answer. As expected, the very old group had a lower accuracy rate than the old group (d = 0.59). The very old group, however, monitored this impairment, since their over-/underconfidence and calibration did not differ from the old group but they displayed a poorer ability to separate correct from incorrect answers (discrimination ability). Possibly, the very old group was able to monitor the level of their over-/underconfidence because they applied general self-knowledge about their memory skills. In contrast, the discrimination of correct from incorrect answers may be more dependent on ability to attend to the features of each retrieved memory.     

Examination results and autopsy findings in assaults on elderly people

As the percentage of elderly people in the population grows, violence against persons of advanced age constitutes an increasing social problem. The findings of the clinical forensic examinations (CE group) and autopsies performed on elderly violence victims (> or = 60 years) between 1999 and 2008 at the Institute of Legal Medicine of the Hanover Medical School were retrospectively analysed. In all, the study material comprised 55 victims of the CE group (35 females and 20 males, median age 73.5 years) and 55 autopsies (33 females and 22 males, median age 72.7 years). In most of the autopsy cases, the suspect was a family member or partner. In contrast, the alleged perpetrator was a stranger in most cases of the CE group. Blunt force injuries were most often found in the CE group victims (63.6%). Altogether, 38.2% (CE group) and 20.0% (autopsy cases) of the violent assaults were associated with robbery. In the majority of the CE cases, the victims suffered potentially or acute life-threatening injuries. In summary, the analysis shows that elderly people frequently become victims of robbery and blunt force injury. In most homicides of old people, the perpetrator is familiar to the victim. In surviving elderly violence victims, the assault is more likely to be reported to the police if the suspect is a stranger.