Application of Demirjian's and Cameriere's Method in Dental Age Estimation of 8-16 Year Old Adolescents from Hunan Han Nationality.

ABSTRACT: Objective To apply Demirjian's and Cameriere's method for dental age estimation of adolescents from Hunan Han nationality, and compare the accuracy of the two methods. Methods A total of 480 orthopantomograms of?8-16 year?old adolescents from Hunan Han nationality?with no special diseases and good nutritional status were collected?by Xiangya Stomatological Hospital of Central South University from January, 2016 to July, 2017, among them 236 males and 244 females. The dental age of each adolescent was determined by Demirjian's method and Cameriere's method, respectively, and the paired t-test of the estimated dental age and the chronological age determined by the two methods was conducted by SPSS 20.0 software to compare the difference between estimated dental age and chronological age. Results Mean chronological age of males and females was 11.91 and 11.88 years, respectively. The estimated dental age determined by Demirjian's method showed an underestimate of chronological age by an average of 0.11 years （males） and 0.15 years （females）, while the estimated dental age determined by Cameriere's method showed an underestimate of chronological age by an average of 0.83 years （males） and 0.72 years （females）. Conclusion Demirjian's method is more accurate than Cameriere's method in dental age estimation of adolescents from Hunan Han nationality, therefore more suitable for dental age estimation of adolescents in this region.

[Research Progress of Vitreous Humor Detection Technique on Estimation of Postmortem Interval].

Estimation of postmortem interval （PMI） plays a crucial role in forensic study and identification work. Because of the unique anatomy location, vitreous humor is considered to be used for estima- ting PMI, which has aroused interest among scholars, and some researches have been carried out. The detection techniques of vitreous humor are constantly developed and improved which have been gradually applied in forensic science, meanwhile, the study of PMI estimation using vitreous humor is updated rapidly. This paper reviews various techniques and instruments applied to vitreous humor detection, such as ion selective electrode, capillary ion analysis, spectroscopy, chromatography, nano-sensing technology, automatic biochemical analyser, flow cytometer, etc., as well as the related research progress on PMI estimation in recent years. In order to provide a research direction for scholars and promote a more accurate and efficient application in PMI estimation by vitreous humor analysis, some inner problems are also analysed in this paper.

Genetic Polymorphisms of 21 STR Loci in Hunan Province-based Han Population.

OBJECTIVES: To investigate the genetic polymorphisms of 21 short tandem repeat （STR） loci （D3S1358, D13S317, D7S820, D16S539, Penta E, D2S441, TPOX, TH01, D2S1338, CSF1PO, Penta D, D10S1248, D19S433, vWA, D21S11, D18S51, D6S1043, D8S1179, D5S818, D12S391 and FGA）. METHODS: A total of 560 blood samples were collected from unrelated healthy individuals of Han population in Hunan Province. Chelex-100 extraction method was applied to the extraction of genomic DNA, and an AGCU EX22 Kit and 9700 STR amplification was used in amplification reactions. The products were separated and analyzed on 310 Genetic Analyzer. RESULTS: A total of 248 alleles were observed, the allelic frequencies ranging from 0.001 to 0.518. Observation of genotype distributions for each locus showed no deviations from Hardy-Weinberg equilibrium except Penta E （P=0.023）. The combined power of discrimination, combined power of exclusion, and combined matching probability of the 21 STR loci were approximately 0.999 999 999 999 999 999 999 999 8, 0.999 999 998, and 1.36×10⁻²5, respectively. CONCLUSIONS: The 21 STR loci show high polymorphisms in the Han population, which can provide valuable data and a theoretical basis for forensic individual identification and paternity testing.

Identification of forensically important flesh flies based on a shorter fragment of the cytochrome oxidase subunit I gene in China.

With the development of molecular identification, there has been a great deal of discussion about the feature of the mitochondrial DNA (mtDNA) fragments. Although longer fragments may minimize stochastic variation across taxa and be more likely to reflect broader patterns of nucleotide divergence, shorter fragments have many advantages, such as quick, easy and economical. Extensive application of long mtDNA segments for species identification cannot always be achieved as a result of constraints in time and money. In the present study, a molecular identification method involving the sequencing of a 272-bp 'barcode' fragment of the mitochondrial cytochrome oxidase subunit I (COI) gene from 55 specimens, representing 7 Chinese sarcophagid species from varying populations, was evaluated. Phylogenetic analysis of the sequenced segments showed that all sarcophagid specimens were properly assigned into seven species, which indicated the possibility of separation congeneric species with the short fragments. The results of this research will be instrumental for the implementation of the Chinese Sarcophagidae database.

The availability of 16S rRNA for the identification of forensically important flies (Diptera: Muscidae) in China.

Many species of Muscidae are cosmopolitan synanthropic insects. It is frequently found on dead bodies after death, so an accurate identification of each species is necessary for the correct estimation of the postmortem interval (PMI). Identification species of Muscidae is traditionally performed through their morphological features. However, the morphological similarity of Muscidae in the level of species usually poses a challenge for forensic entomologists. Therefore a molecular method used 16S rRNA sequence on mitochondrial DNA was established for species identification. In this study, a 289 base pair region of mitochondrial DNA (mtDNA) coding for 16S rRNA was investigated for identification of the following forensically important species of Muscidae. The specimens were from four genera, including 18 Musca domestica (Linnaeus, 1758), 2 Ophyra spinigera (Stein, 1910), 2 Ophyra chalcogaster (Wiedemann, 1824), 1 Morellia hortorum (Fallén, 1817), and 1 Fannia canicularis (Linnaeus, 1761). 16S rDNA region allowed the identification of these species of Muscidae, indicating the possibility of separation congeneric species with molecular method.

Normal fetal brain development: MR imaging with a half-Fourier rapid acquisition with relaxation enhancement sequence.

PURPOSE: To analyze normal maturation of the fetal brain with half-Fourier rapid acquisition with relaxation enhancement (RARE) magnetic resonance (MR) imaging. MATERIALS AND METHODS: The normal brains of 25 fetuses of 12-38 weeks gestational age were examined in utero with half-Fourier RARE imaging. Gyrus maturation, gray and white matter differentiation, ventricle-to-brain diameter ratio, and subarachnoid space size were evaluated with respect to gestational age. RESULTS: At 12-23 weeks, the brain had a smooth surface, and two or three layers were differentiated in the cerebral cortex. At 24-26 weeks, only a few shallow grooves were seen in the central sulcus, and three layers, including the immature cortex, intermediate zone, and germinal matrix, were differentiated in all fetuses. At 27-29 weeks, sulcus formation was observed in various regions of the brain parenchyma, and the germinal matrix became invisible. Sulcation was seen in the whole cerebral cortex from 30 weeks on. However, the cortex did not undergo infolding, and opercular formation was not seen before 33 weeks. At 23 weeks and earlier, the cerebral ventricles were large; thereafter, they gradually became smaller. The subarachnoid space overlying the cortical convexities was slightly dilated at all gestational ages, most markedly at 21-26 weeks. CONCLUSION: Changes in brain maturation proceed through stages in an orderly and predictable fashion and can be evaluated reliably with half-Fourier RARE MR imaging.