Free amino acid concentrations in vitreous humor and cerebrospinal fluid in relation to the cause of death and postmortem interval

We studied free amino acids in vitreous humor and cerebrospinal fluid from 58 cadavers in the course of routine medicolegal autopsies in the city of Granada. The main objective was to establish whether free amino acids contents in these fluids were related with the cause of death, postmortem interval, and severity of the classic signs of asphyxia. The amino acids (aspartic acid, glutamic acid, serine, glutamine, glycine/threonine/histidine, citruline, arginine, alanine, taurine, GABA, tirosine, valine, methionine, isoleucine, phenylalanine/tryptophan, leucine, and lysine) were quantified by high performance liquid chromatography. There were no statistically significant differences in amino acids concentrations in vitreous humor when the different causes of death were considered. Our results did not show any statistically significant relationship when asphyxial score was plotted against the vitreous content of each amino acid. A statistically significant increase with postmortem interval was observed in vitreous taurine (r = 0.3191, p = 0.01461), glutamate (r = 0.4323, p = 0.0007) and particularly in aspartate (r = 0.4508, p = 0.0003).     

多指标正交试验优选炮苍耳子中酚酸类成分的提取工艺

目的 优选苍耳子中酚酸类成分的最佳提取工艺。方法 以苍耳子浸膏得率、5种酚酸类成分及总酚酸的含量为指标,通过正交试验设计,优选出苍耳子中酚酸类成分的最佳水提取工艺。结果 所优选出的最佳提取工艺为10倍量水,浸泡30 min,提取3次,每次90 min。其中提取次数对提取工艺的影响,差异具有统计学意义（P＜0.05）。结论 所选用的提取工艺稳定、简便、可靠,为进一步提取苍耳子中酚酸类成分提供实验参考。     

Wilson病认知功能障碍与肠道菌群的相关性研究

目的 探讨Wilson病(Wilson’s disease, WD)认知功能障碍与肠道菌群的关系,以期为临床治疗WD合并认知功能障碍提供理论基础。方法 选取38例WD伴认知功能障碍的患者作为观察组,同时选取32例WD不伴认知功能障碍的患者为对照组,取大便样品进行16S rRNA基因测序技术分析,通过检测两组患者肠道菌群的组成及其丰度,探讨两者之间的相关性。结果 在门水平上,与对照组比较,观察组拟杆菌门和放线菌门丰度明显升高(P<0.05),厚壁菌门和变形菌门丰度明显降低(P<0.05);在科水平上,与对照组比较,观察组双歧杆菌科、紫单胞菌科、拟杆菌科、产碱杆菌科、理研菌科、乳酸菌科、韦荣氏球菌科丰度明显升高(P<0.05),梭菌科、科里杆菌科、未分类拟杆菌、肠杆菌科、毛螺菌科、乳球菌科、普氏菌科、链球菌科丰度明显降低(P<0.05);在属水平上,与对照组比较,观察组乳酸菌属、小杆菌属、乳球菌属、柯林斯氏菌属、另枝菌属、拟杆菌属、双歧杆菌属、帕拉斯氏菌属丰度明显升高(P<0.05),直肠真杆菌属、布劳特氏菌属、克雷伯氏菌属、栖粪杆菌属、普雷沃氏菌属、链球菌属...     

Cell free DNA as a component of forensic evidence recovered from touched surfaces

In the course of a criminal investigation, DNA is often recovered from items that have been handled by an individual. Whilst there have been studies investigating the propensity of different individuals to deposit DNA, little is known about the factors involved in the transference of DNA through touch. This investigation seeks to clarify some of the underlying processes involved in DNA transfer, as to better understand the significance of so-called “touch DNA” evidence (tDNA). It was shown that an average yield of 11.5 ng of DNA could be recovered from 1 mL cell-free sweat samples leading to the hypothesis that cell-free nucleic acids (CNAs) of a suitable length for standard DNA profiling are transferred during handling/touching items. A method of standardization of tDNA deposition was developed to overcome the significant sample to sample variability in DNA levels characteristic of tDNA samples. The glass bead method allowed the creation of identical tDNA sample sets, thus permitting direct comparisons to be made in the efficiency of various extraction methods. Extraction methods designed to optimize CNA recovery from touched articles resulted in comparable yields in a general population study, however the methods resulted in a twofold increase in DNA yields from touched items touched by individuals with sweaty hands. These results suggest that the CNA component of touched surfaces should be included to maximize profiling success of tDNA.     

氨解法合成4‘—羟基去甲—1—脱氧—1—氨基鬼臼脂素

为实现鬼臼脂素１－羟基直接转化成氨基的合成并降低生成成本。方法：使用亚硫酸氢铵、ＰＰＡ等试剂，在一定压力下通入氮气。结果：成功合成４’－羟基去甲－１－脱氧－１－氨基鬼臼脂素。结论：该方法操作简单，产率高，具有良好的实用价值。     

Locked nucleic acids: Increased trace DNA amplification success with improved primers

Locked nucleic acids (LNAs) are a conformationally restricted DNA analog, which can be incorporated into oligonucleotides to increase binding strength. To investigate if LNAs increase amplification success for trace DNA samples in a forensic context, primer sequences for four routinely used STR loci (FGA, D7S820, D13S317 and D18S51) have been altered to include LNA bases. The LNA modified primers display a broader tolerance to a range of reaction conditions compared to unmodified DNA primers, with higher T_ms giving increased specificity. Increased peak heights, improved peak height ratios and decreased template requirements were seen with LNA primers. The increased amplification success of LNA primers, and broader range of optimal reaction conditions, suggest that using LNA primers for multiplex STR genotyping assays could be highly beneficial for trace DNA genotyping.     

Assessment of the Effects Exerted by Acid and Alkaline Solutions on Bone: Is Chemistry the Answer?

The treatment of corpses with extremely acid or basic liquids is sometimes performed in criminal contexts. A thorough characterization by chemical analysis may provide further help to macroscopic and microscopic analysis; 63 porcine bone samples were treated with solutions at different pH (1–14) for immersion periods up to 70 days, as well as in extremely acidic sulfuric acid solutions (9 M/18 M) and extremely basic sodium hydroxide. Inductively coupled optical emission spectrometry (ICP‐OES)/plasma mass spectrometry (ICP‐MS), Fourier transform infrared spectroscopy (FT‐IR), energy dispersive X‐ray analysis (EDX), X‐ray powder diffraction (XRPD), and scanning electron microscopy (SEM) showed that only the sulfuric acid solution 18 M was able to completely dissolve the sample. In addition, chemical analysis allowed to recognize the contact between bone and substances. Hydrated calcium sulfate arose from extreme pH. The possibility of detecting the presence of human material within the residual solution was demonstrated, especially with FT‐IR, ICP‐OES, and EDX.     

Chemical Differences Are Observed in Children’s Versus Adults’ Latent Fingerprints as a Function of Time*

Abstract: The identification of aged latent fingerprints is often difficult, especially for those of children. To understand this phenomenon, the chemical composition of children’s versus adults’ latent fingerprints was examined over time using Fourier transform infrared microscopy. Hierarchical cluster analysis revealed that children’s and adults’ prints were distinguishable for up to 4 weeks after deposition, based on differences in sebum composition. Specifically, adults had a higher lipid content than children, but both decreased over time, attributable to the volatility of free fatty acids. The aliphatic CH₃, aliphatic CH₂, and carbonyl ester compositions changed differently in adults versus children over time, consistent with higher cholesterol and cholesteryl esters in children’s prints and wax esters and glycerides in adults’ prints. Thus, fingerprint composition changes with time differently in children versus adults, making it a sensitive metric to estimate the age of an individual, especially when the age of the print is known.     

The Initial Changes of Fat Deposits During the Decomposition of Human and Pig Remains

Abstract:  The early stages of adipocere formation in both pig and human adipose tissue in aqueous environments have been investigated. The aims were to determine the short-term changes occurring to fat deposits during decomposition and to ascertain the suitability of pigs as models for human decomposition. Subcutaneous adipose tissue from both species after immersion in distilled water for up to six months was compared using Fourier transform infrared spectroscopy, gas chromatography-mass spectrometry and inductively coupled plasma-mass spectrometry. Changes associated with decomposition were observed, but no adipocere was formed during the initial month of decomposition for either tissue type. Early-stage adipocere formation in pig samples during later months was detected. The variable time courses for adipose tissue decomposition were attributed to differences in the distribution of total fatty acids between species. Variations in the amount of sodium, potassium, calcium, and magnesium were also detected between species. The study shows that differences in total fatty acid composition between species need to be considered when interpreting results from experimental decomposition studies using pigs as human body analogs.     

Histamine, cortisol and organ changes in fatal anaphylactic shock in guinea-pigs

Anaphylactic shock was produced in guinea-pigs by sensitizing them with oval albumin and challenging them with an intracardial dose (rapid shock) or intraperitoneal dose (slow shock) of the same protein 4 weeks later. The animals died within 5 min or 30 min, respectively. Blood for biochemical assays was taken by cardiac puncture and tissue samples were excised for histamine assay and histological studies. High concentrations of histamine (4-5 times the control values) were measured in the animals which died rapidly, but not in the others, whereas the histamine content of the stomach wall and lungs was decreased both in rapid and slow shock. Plasma cortisol was low in the rapid shock group. Plasma free fatty acids were high in both groups, but glucose only in the slow shock group. The lungs were distended, indicating bronchial obstruction. Occasional platelet agglutinations were seen in the lung veins. The most promising signs regarding the diagnosis of death from anaphylaxis were the high plasma histamine values and acute emphysema.