Forensic Science Review最新文献

Male-specific DNA profiling using nonrecombining Y-chromosomal genetic markers is becoming ubiquitous in forensic genetics, with many laboratories and jurisdictions taking advantage of the benefits that Y-chromosome short tandem repeat (Y-STR) profiling can bring. The current suite of 9-17 core Y-STRs, available as commercial kits, perform adequately for identifying male lineages in many populations, a feature highly suitable for excluding a male suspect from involvement in crimes such as sexual assaults where autosomal STR profiling is often troubled. However, there is a growing need to achieve higher resolution in paternal-lineage differentiation as adventitious matches between unrelated males are becoming increasingly common with the increasing size of Y-STR haplotype-frequency databases. Furthermore, with the currently used Y-STRs, male relatives (both close and distant) usually cannot be separated, marking a strong limitation in forensic applications as conclusions cannot be drawn on the individual level as desired. Performing Y-chromosome analysis in familial testing, which outperforms autosomal STR profiling in certain deficiency cases, with the current Y-STR sets can be troubled by mutations that complicate relationship-probability estimations. To overcome these limitations, considerable research has been performed over recent years to identify and characterize additional Y-STRs. This review summarizes the forensic performance of current sets of Y-STRs, points out their limitations in the three main areas of forensic Y-STR applications (male-lineage differentiation, male-relative differentiation, and paternity/familial testing), and discusses why and which additional Y-STRs are suitable to improve forensic Y-chromosome analysis in the future.

Forensic DNA typing has been a constantly evolving field driven by innovations from academic laboratories as well as kit manufacturers. Central to these technological advances has been the transition from multilocus-probe restriction fragment length polymorphism (RFLP) methods to short tandem repeat (STR) PCR-based assays. STRs are now the markers of choice for forensic DNA typing and a wide variety of commercial STR kits have been designed to meet the various needs of a forensic lab. This review provides an overview of the commercial STR kits made available since the year 2000 and explains the rationale for creating these kits. Substantial progress has been made in key areas such as sample throughput, speed, and sensitivity. For example, a significant advancement for databasing labs was the capability of direct amplification from a blood or buccal sample without need for DNA extraction or purification, enabling increased throughput. Other key improvements are greater tolerance for inhibitors (e.g., humic acid, hematin, and tannic acid) present in evidence samples, PCR cycling times decreased by 1-1.5 h, and greater sensitivity with improved buffer components and thermal cycling conditions. These improvements that have been made over the last 11 years have enhanced the ability of forensic laboratories to obtain a DNA profile from more challenging samples. However, with the proliferation of kits from different vendors the primer binding sequences of the loci vary, which could result in discordant events that would need to be resolved either via a database-driven software solution or simply by evaluating discordant samples with multiple kits.

A reliable method for the quantitative analysis of ethanol in microvolumes (50-100 μL) of blood became available in 1922, making it possible to investigate the absorption, distribution, metabolism, and excretion (ADME) of ethanol in healthy volunteers. The basic principles of ethanol pharmacokinetics were established in the 1930s, including the notion of zero-order elimination kinetics from blood and distribution of the absorbed dose into the total body water. The hepatic enzyme alcohol dehydrogenase (ADH) is primarily responsible for the oxidative metabolism of ethanol. This enzyme was purified and characterized in the early 1950s and shown to have a low Michaelis constant (km), being about ~0.1 g/L. Liver ADH is therefore saturated with substrate after the first couple of drinks and for all practical purposes the concentration-time (C-T) profiles of ethanol are a good approximation to zero-order kinetics. However, because of dose-dependent saturation kinetics, the entire postabsorptive declining part of the blood-alcohol concentration (BAC) curve looks more like a hockey stick rather than a straight line. A faster rate of ethanol elimination from blood in habituated individuals (alcoholics) is explained by participation of a high km microsomal enzyme (CYP2E1), which is inducible after a period of chronic heavy drinking. Owing to the combined influences of genetic and environmental factors, one expects a roughly threefold difference in elimination rates of ethanol from blood (0.1-0.3 g/L/h) between individuals. The volume of distribution (Vd) of ethanol, which depends on a person's age, gender, and proportion of fat to lean body mass, shows a twofold variation between individuals (0.4-0.8 L/kg). This forensic science review traces the development of forensic pharmacokinetics of ethanol from a historical perspective, followed by a discussion of important issues related to the disposition and fate of ethanol in the body, including (a) quantitative evaluation of blood-alcohol curves and the factors influencing the peak concentration in blood (Cmax) and the time of its occurrence (tmax), (b) biological variations in the ADME of ethanol, including the apparent volume of distribution (Vd or rho), the disappearance rate from blood (β or k0), and the disposal rate by the entire body in 1 h (B60), and (c) questions about ADME of ethanol often arising during the prosecuting of accused drunken drivers.

Alcohol abuse represents a highly relevant medical, social, and economic problem all over the world. The diagnosis of conditions of alcohol use or abuse is complex, requiring different and integrated methodologies; among them the use of biomarkers is a very helpful and objective tool. This review article discusses the currently available biomarkers of alcohol abuse, showing their positive and negative characteristics in terms of detection window, diagnostic sensitivity, diagnostic specificity, and analytical feasibility. Particular attention is dedicated to the most used biomarkers, represented by liver enzymes (AST, ALT, and GGT), MCV, CDT, EtG and EtS, FAEE, and PEth. A critical analysis of the different biomarkers showed wide variability in terms of detection window, sensitivity, and specificity. On this basis, the choice of any indicator should depend on the aim and context for which the diagnosis of alcohol abuse is required (e.g., clinical, fitness for driver's license, fitness to work, child custody). Moreover, this study showed that the diagnosis of alcohol abuse cannot be based only on the use of biomarkers, but it must also consider the integration of anamnestic, clinical, instrumental, and laboratory data.

Alternative medicine has historically been very popular in developing countries. In this context, self-medication with herbal formulations has increased in both developing and developed nations in recent years. The adulteration of such formulations violates the laws of many countries because it can lead to unpredictable effects in the human body, either due to the isolated effects of an added pharmaceutical or to its interaction with other substances present in the formulation. The development of methodologies for the screening and quantification of adulterated samples should be of great interest for analytical, clinical, and forensic scientists. This review aims to provide a comprehensive approach to this topic and to discuss adulteration cases related to herbal formulations reported in the literature over the last few decades. Furthermore, a classification of the most commonly found synthetic adulterants that are linked to the active principle of herbal formulations was proposed according to their pharmacological action. The available analytical methodologies for the identification of adulteration practices are presented in a systematic and comprehensive way.

Parts from animals that are now endangered species (such as bear bile, rhino horn, and tiger bone) have long been important ingredients of traditional Chinese medicine (TCM). Deeply believing in the potency of these ingredients and coupled with substantial gains in wealth of the population in Taiwan in the 1980s, ugly scenarios came to light. Taiwan quickly became the target of investigation pursued by international wildlife conservationists. To provide scientific bases for the government's investigation efforts, morphological, chemical/physical, and genetic methods were developed to characterize TCM products. This review focuses on Taiwanese scientists' efforts on the following topic matters: (a) morphological approach to identify CITES-listed species from the turtle shells traded in the TCM market; (b) chromatographic and spectrophotometric methods for the identification and differentiation of bile products of different animal origins; and (c) gas chromatography-mass spectrometry method for the analysis of deer musk components and alleged musk products.

To control illegal wildlife-product trade and protect endangered species of animals, unambiguous identification of the animal specimens is vitally important. Genetic approaches were adopted to identify animal species for conservation and to prevent their fraudulent misidentification in Taiwan, especially for samples of animal residues, powders, and processed products. PCR or nested PCR based on the nature of DNA was used for amplification of cyt b, COI, CHD, and D-loop DNA fragments. Sequences of these fragments were compared with those registered in DNA databases and phylogenetic analysis was performed. The established methods were applied in forensic cases for support of conservation efforts and they were proved to be robust. For conservation animal identification, various samples seized by law enforcement agents have been identified by our systems as rhinoceros horns, Indian sawback turtles, shahtoosh, ivories, dolphins, whales, etc. The systems were also successfully used in investigating the illegal trade of commercial turtle shells and the fraudulent misidentification of food contents on product labels in Taiwanese markets. This review summarizes the work conducted in our laboratory and describes the Taiwan experience.

Wildlife forensic science is a relatively recent development to meet the increasing need of the criminal justice system where there are investigations in alleged transgressions of either international or national legislation. This application of science draws on conservation genetics and forensic geneticists from mainstream forensic science. This review is a broad overview of the history of forensic wildlife science and some of the recent developments in forensic wildlife genetics with the application of DNA developments to nonhuman samples encountered in a forensic science investigation. The review will move from methods to look at the entire genome, when there is no previous knowledge of the species studied, through methods of species identification, using DNA to determine a possible geographic origin, through to assigning samples to a particular individual or a close genetic relative of this individual. The transfer of research methods into the criminal justice system for the investigation of wildlife crimes has been largely successful as is illustrated in the review. The review concludes with comments on the need for standardization and regulation in wildlife forensic science.

CITES is a 35-year-old convention with a current total of 175 signatories, or parties. It regulates international trade in live specimens and products of more than 30,000 animal and plant species under three different trade regimes. CITES has clearly proved its importance for nature conservation, but its regulations often are difficult to implement and enforce, leading to unacceptably high levels of unsustainable and illegal trade in many wildlife species. There are ways, however, to improve the situation and to make compliance with CITES regulations both easier and more attractive.

Wildlife forensics is an emerging field and involves a number of players including the international community itself, national police agencies, nongovernmental organizations (NGOs), and forensic and scientific experts. Collectively, these players attempt to prevent or prosecute crimes that specifically target wildlife, and deal with what is becoming an increasingly burgeoning global problem. The number and type of methods that are used to answer questions related to wildlife crimes and to recover evidence for prosecutions are numerous. This paper outlines the key questions that concern crimes perpetrated against wildlife and provides a context for those methods that fall generally under the headings of morphological and chemical. A commentary is provided on the relative success of these methods and how they relate either directly or indirectly to evidence gathering and to one another. It is clear that a considerable forensic toolkit exists, and more could be achieved with further developments of newer methods.