[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.

The association between MLH1 -93 G>A polymorphism of DNA mismatch repair and cancer susceptibility: a meta-analysis.

DNA mismatch repair, known as a fundamentally biological pathway, plays key roles in maintaining genomic stability, eliminating mismatch bases and preventing both mutagenesis in the short term and cancerogenesis in the long term. Polymorphisms of MLH1 in individuals may have an effect on the DNA repair capacity and therefore on cancer risk. Recently, emerging studies have been done to evaluate the association between MLH1 -93 G/A polymorphism and cancer risk in diverse populations. However, the results remain conflicting rather than conclusive. In this meta-analysis, we assessed reported studies of association between the MLH1 -93 G/A polymorphism and cancer risk including 13 691 cancer cases and 14 068 controls from 17 published studies. A borderline significant association between the MLH1 -93 G/A polymorphism and cancer risk was observed in overall analysis [heterozygote: odds ratio (OR) = 1.15; 95% confidence interval (CI) 1.05-1.26; homozygote: OR = 1.21; 95% CI, 1.04-1.40; dominant model: OR = 1.13; 95% CI 1.01-1.26; recessive model: OR = 1.21; 95% CI 1.07-1.35, respectively]. In subgroup analysis by ethnicity, significantly increased risks were found in Asian population and mixed population but not in Caucasian population. After stratified analysis according to the quality of literature, increased cancer risks were observed in the studies of lower quality but not in the studies of higher quality. Similarly, elevated cancer risks were observed in hospital-based studies but not in population-based studies. These findings showed no persuasive evidence that MLH1 -93 G/A polymorphism was associated with an increased risk of cancer. On the conservative standpoint, well-designed population-based studies with larger sample size in different ethnic groups should be performed to further confirm these results.

Genetic polymorphisms of DNA repair gene XRCC1 and risk of uterine leiomyoma.

The objective was to study the relationship between the polymorphisms of the DNA repair gene XRCC1 Arg399Gln, Arg194Trp, and Arg280His uterine leiomyoma in a Chinese population. In the case-control study, we compared the XRCC1 gene polymorphism of 136 uterine leiomyoma patients and 140 healthy controls by using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The results suggested that the genotype Arg/Arg of codon 280 was significantly different from its heterozygote (odds ratio [OR] = 3.633, 95% confidence interval [CI]: 2.147-6.148). In conclusion, the results suggest that polymorphism of XRCC1 Arg280His was associated with the increased risk of uterine leiomyoma in a Chinese population.

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.

[Haplotype and heteroplasmy in the HV II region of mtDNA in human blood detected by PCR-DGGE].

OBJECTIVE: To establish a simple and effective technique for detecting haplotype and heteroplasmy of mtDNA, and investigate their frequencies in Chinese Han population. METHODS: The fragments from 29-290 nt of mtDNA HV II from peripheral leukocytes of 200 unrelated Wuhan Han individuals were analyzed by using PCR-DGGE technique. RESULTS: Seventeen haplotypes were found in the range of 29-290 nt, and the haplotype diversity (HD) was 0.8844. The heterogeneity was observed from 4 individuals, and its frequency was 2%. CONCLUSION: PCR-DGGE is a simple, sensitive and effective technique in analyzing polymorphism and heteroplasmy of mtDNA, and can be used in forensic practice.

[Genetic polymorphism of 23 Y chromosome biallelic markers in Wuhan Han population].

To search polymorphic Y chromosome biallelic markers in Chinese Han population, and obtain their population genetic data. Genotyping of 23 biallelic markers on human Y chromosome (M7, M9, M50, M88, M89, M95, M111, M117, M119, M121, M122, M134, M159, M164, M175, M214, LINE1, MSY2, RPS4Y711, SRY465, IMS-JST164520, IMS-JST021354 and IMS-JST003305) were carried out in a sample of 160 unrelated Chinese male individuals living in Wuhan using fragment length discrepant allele specific PCR (FLDAS-PCR) and PAGE technique. In all 23 biallelic markers, genetic polymorphism were identified for 20 loci in Wuhan Han population except for M50, M159 and M164, and the ranges of gene diversity (GD) were 0.0126-0.4855. A total of 35 different haplogroups (Hg1-35) were observed and the haplogroup diversity (HD) was 0.9471. The haplogroups formed by 20 biallelic markers are highly polymorphic, and can be used in forensic science and population evolution studies.

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).