Progress in the Application of Magnetic Nanoparticles in Forensic Trace Analysis.

Given the complexity of biological samples and the trace nature of target materials in forensic trace analysis, a simple and effective method is needed to obtain sufficient target materials from complex substrates. Magnetic nanoparticles (MNPs) have shown a wide range of application value in many research fields, such as biomedicine, drug delivery and separation, due to their unique superparamagnetic properties, stable physical and chemical properties, biocompatibility, small size, high specific surface area and other characteristics. To apply MNPs in the pretreatment of forensic materials, maximize the extraction rate of the target materials, and minimize interference factors to meet the requirements of trace analysis of the target materials, this paper reviews the application of MNPs in the fields of forensic toxicological analysis, environmental forensic science, trace evidence analysis and criminal investigation in recent years, and provides research ideas for the application of MNPs in forensic trace analysis.

[Research Progress on Forensic Entomotoxicology].

Forensic entomotoxicology is a branch of forensic medicine, which applies entomology, toxicology and other related studies to solve the poisoning cases. It has an obvious advantage in the investigation on poisoning death. Based on the expounding definition and research of entomotoxicology, this paper reviews research progress and application value in some aspects of forensic medicine, such as the effects of drugs/toxins on the growth and development of sarcosaphagous insects and the qualitative and quantitative analysis of the drugs/toxins in the poisoned body tissue.

[One-step methylation variable position analysis technology in single-tube].

OBJECTIVE: To develop the single-tube one-step methylation variable position (MVP) analysis technology-single-tube post-digestion PCR-melting curve analysis (PDP-MCA). METHODS: Based on differentially methylated region (DMR) reported previously as the model, a set of primers with different melting temperatures of products in the two sides of MVP were designed. By using the FastDigest methylation-sensitive restriction enzyme (MSRE), DNA digestion, multiplex amplification, MCA detection and MCA profiles were performed in a single reaction tube. Same samples (peripheral venous blood, semen, and vaginal fluid, 5 samples each type) were tested by single-tube one step MVP and traditional MSRE-PCR MCA technology. To verify the feasibility of this method, the results were compared with that of the traditional technology. The MCA/HRM profiles of different samples were analyzed and compared. RESULTS: When the melting temperature of the fragments had a differential of 2 degrees C, the MCA melting peaks separated well, and MCA detection after multiplex amplification was successful. The single-tube PDP-MCA assay was developed, which integrated multiple reactions (digestion, amplification and detection) into one tube. By this method, the sample-specific profiles and data were analyzed in 2 h, which is similar to that of the traditional method. The rapid classifications of the samples were also realized. CONCLUSION: Multiplex MVPs can be analyzed in a single closed-tube. The single-tube PDP-MCA technology is a simple, fast, and automatable method. It can be used for detection of DNA methylation variations.

[Effect of ketamine on the development of Chrysomya megacephala (Diptera : Calliphoridae)].

OBJECTIVE: To research the pattern of larvae and pupae development when exposed to ketamine. METHODS: The larvae of Chrysomya megacephala were reared in artificial diet containing ketamine with concentration of 0, 25, 50 and 100 mg/kg respectively at 32 degrees C, 28 degrees C and 24 degrees C in environmental chamber with a 12-h photoperiod and 75% humidity. 10 samples were collected from each group every 12 h from the 16th h after hatching to pupation. The max body length, weight of the larvae, growth rate of body length, weight and developmental duration of each stage were observed. RESULTS: The average length and weight in the treatment groups were significantly less than the control before achieving the maximum (P < 0.05), and the growth rate of 1/2LD50 group at 24 degrees C was most retarded. No dose dependence were observed among the ketamine fed groups. The effect of ketamine dose, temperature and their interaction on larval length and weight was statistically significant (P < 0.01). The effect of ketamine dose, temperature and their interaction account for, respectively, 20.9%, 60.2% and 18.9% of the total effect on growth of larval length, and they account for 8.3%, 85.6% and 6.1% of the total effect on growth of larval weight. The duration of larval stage in treatment groups was significantly delayed in comparison to the control at different temperatures (P < 0.05), and the duration of prepupal stage in treatment groups was significantly delayed (P < 0.05). However, the duration of pupal stage in treatment groups at 24 degrees C was significantly shorter than the control (P < 0.05). CONCLUSION: The time achieving maximum length and weight was significantly delayed, which results in an increased development duration of larval and prepupal stages, indicating that ketamine inhibits the growth of the larvae of C. megacephala.

False homozygosities at CSF1PO loci revealed by discrepancies between two kits in Chinese population.

During the course of paternity test, three samples in two cases were apparently homozygous at the CSF1PO locus using AmpFlSTRs Identifiler PCR Amplification kits, but using the PowerPlexs 16 kit, the three individuals were found to be heterozygous. This puzzling problem was solved by using multiple analytical approaches, including the use of different primer pairs and the characterization of the mutation causing the ''null allele.'' Dropout was caused by a single mutation event in the presumptive binding site of the forward primer. While the frequency of these silent alleles remains low (0.5% in our study), it is suggested that appropriate measures should be taken for database comparisons and that allelic dropout should be further investigated by sequence analysis and be reported to the forensic community.

[Advances in identification of semen stains].

Stain identification has long been a task in forensic biology. The identification of semen stain, one of the most common human stains, can provide crucial information for crime scene reconstruction and forensic investigation. Traditional detection of semen stain depends largely on the microscopic identification of spermatozoa, enzyme activity-based methods or antigen-antibody reactions. These morphological, proteinological and zymological approaches, however, are apparently inadequate in identifying tiny, admixed, degraded or contaminated samples. With the development of transcriptomics and epigenetics, many semen-specific mRNA markers, such as protamine-1 (PRM1) and -2 (PRM2), have been applied to semen and semen stain identification. Messenger RNA profiling shows great promise in identifying tissues as demonstrated by the recognition of specific markers. Further more, studies on tis-sue-specific differential DNA methylation will provide a scrumptious way of identifying difficult samples.

[Applications of Alu family in forensic DNA analysis].

Alu family is the primate specific short interspersed repetitive elements (SINEs). Its abundance and diversity distribution in genome, high methylation level and polymorphic for insertion make them ideally suitable as tools in forensic applications. The application of A4 lu sequence in forensic genomics, include DNA quantitation, race determination, species and gender identification, personal identification, paternity testing and whole-genome amplification. The principles and characteristics of these Alu-based techniques are also summarized. The prospect of Alu as forensic molecular marker is discussed as well.

[The relationship of injury timing with the change of neuronal apoptosis and the expression of caspase-3 after brain contusion].

OBJECTIVE: To investigate and analyze the changes of neuronal-apoptosis and the expression of caspase-3 for finding out a new method of injury timing after brain contusion in human. METHODS: The tissue was stained by TUNEL for apoptosis and by immunohistochemistry for caspase-3. Image analysis technique was employed. RESULTS: The nerve cells stained positive by TUNEL and Caspase-3 immunohistochemistry were distributed in the penumbra and central area. Both these areas were in striking contrast with the distal area or those of control group. The positive staining was more prominente in penumbra area than in central area (P < 0.05). The changes of TUNEL staining and expression of Caspase-3 in penumbra area gradually increased with the survival period after injury; they were parallel to each other. There were linear relationships between the time of injury in 48 hours and the increase in the mean of integral optical density (IOD), the coefficient of correlation (r) being 0.93 and 0.69 for the two staining methods, and two linear regression formulae were induced, respectively. CONCLUSION: Observations on the increasing of neuronal apoptosis and Caspase-3 expression in relation with the survival period after injury could be utilized in the timing of brain contusion.

[Retrospective analysis of autopsy on 49 cases of medical tangles in perinatal period].

Medical tangles caused by the death of women and infants in perinatal period are very normal in the forensic appraisal. The author collected and analyzed 49 cases of these tangles from many aspects, such as sex and age of the dead, hospital,information of autopsy, fault of medical action and so on,and discovered the normal causes of death, medical action's effects and the causes of tangle. It would be useful to the forensic appraisal, settlement and prevention of these medical tangles.

No association between estrogen receptor beta polymorphisms and uterine leiomyoma.

Numerous candidate genes have been proposed as susceptibility factors for the development of uterine leiomyoma. Interaction of estrogen receptor alpha (ESR1) and estrogen receptor beta (ESR2) plays a pivotal role in tunica muscularis uteri cell proliferation, differentiation, and tumorigenesis of myometrium. To our knowledge, no study has examined the relationship between the ESR2 and uterine leiomyoma. The aim of the study was to evaluate the association of ESR2 polymorphisms with uterine leiomyoma in Chinese women. We investigated two common ESR2 polymorphisms, rs1256049 (G1082A) and rs928554 (Cx + 56 A --> G), to find their association with uterine leiomyoma risk by polymerase chain reaction-restriction fragment length polymorphism and DNA sequencing method. A total of 150 Chinese women with clinically diagnosed uterine leiomyoma and 150 healthy, normal Chinese women were included in the study. The results suggest that there were no significant differences in the genotype and allele frequencies of ESR2 polymorphisms between uterine leiomyoma patients and controls in Chinese women (p > 0.05). Further studies are still needed to explore the complicated interaction between environmental factors and ESR2 polymorphisms in the risk of uterine leiomyoma, particularly in ethnically different populations.

XRCC1 codon 280 and ERCC2 codon 751 polymorphisms and risk of esophageal squamous cell carcinoma in a Chinese population.

Numerous candidate genes have been proposed as susceptibility factors for the development of esophageal squamous cell carcinoma (ESCC). XRCC1 (X-ray cross-complementing group 1) codon 280 and ERCC2 (excision repair cross complementing group 2) codon 751 polymorphisms were studied in ESCC in a Chinese population. The aim of this study is to investigate the potential association between single-nucleotide polymorphisms (SNP) of XRCC1 codon 280 His and ERCC2 codon 751 Gln polymorphisms and ESCC. Peripheral blood samples of 200 cases and 200 age-and-gender matching controls were collected from a Chinese population and the two polymorphisms were studied by means of polymerase chain reaction (PCR) restriction fragment length polymorphism techniques. Our results showed that XRCC1 codon 280 His allele had no significant difference between ESCC patients and normal controls (P > 0.05), while ERCC2 codon 751Gln allele was associated with a borderline decrease of ESCC (odds ratio [OR] = 0.628, 95% confidence interval [CI]: 0.400-0.986).