Shigemi Oshida

Estimation of Post-Mortem Interval from Rectal Temperature by Use of Computer

The simulation model of the approximate equations derived from the infinite cylinder was used to investigate the applicability of the theoretical curve to the actual one of rectal temperature. The rectum was found by the computer tomography to be near to the junction of the anterior three-quarters and the posterior quarter inside the body, and this result was employed in the simulation. The method of estimating the postmortem interval, in which two recordings of rectal temperature were used, was considered to be useful enough as it can be applied to any case in practice. As reported by Akaishi et al., fluctuation of less than 2 °C in the ambient temperature was shown by the simulation to have little effect on the rectal temperature curve.

Genetic polymorphisms of eight X-chromosomal STR loci in the population of Japanese

The genetic polymorphisms of eight X-chromosomal short tandem repeats (STR) DXS10135, DXS8378, DXS7132, DXS10074, HPRTB, DXS10101, DXS10134 and DXS7423 were analyzed in a sample of 492 unrelated males (283) and females (209) from the Japanese population. Multiplex PCR amplification was performed using the Mentype Argus X-8 PCR amplification kit. The haplotype frequencies within the four linkage groups were studied for the 283 examined Japanese males. Allele frequencies of eight X-STR loci were calculated separately for males and females, and exact tests demonstrated no significant deviations from Hardy-Weinberg equilibrium. Several microvariant and rare alleles were observed, and forensic efficiency parameters were calculated. The combined powers of discrimination of the loci in men and women were 0.999995 and 0.9999999999988, respectively.

Estimation of postmortem interval from rectal temperature by use of computer--relationship between the rectal and skin cooling curves.

The deep body temperatures at depths of 0.5 cm and of 1 cm and the skin and rectal temperatures of the living rabbit were monitored in order to clarify the initial condition. It was revealed that there is a temperature gradient similar to the logarithmic curve from the core to the surface. Taking this temperature gradient into consideration, the computer simulation model composed of the approximate equations was used to investigate the adaptability of the theoretical cooling curves to the experimental rectal and skin cooling curves. Our computer simulation model proved that the theoretical cooling curves reproduced well both the experimental rectal and skin cooling curves regardless of changes in the ambient temperature.

Direct and rapid PCR amplification using digested tissues for the diagnosis of drowning

We developed a direct and rapid method for the diagnosis of death by drowning by PCR amplification of phytoplankton DNA using human tissues. The primers were designed based on the DNA sequence of the 16S ribosomal RNA gene (16S rDNA) of Cyanobacterium. Samples of lung, liver and kidney tissues were collected from 53 autopsied individuals diagnosed as death by drowning. Without DNA extraction, the tissue fragments were incubated directly in a digest buffer developed in this study, for 20 min. Using 1 μL of the tissue digest solution in PCR, the 16S rDNA was successfully amplified. The specific 16S rDNA fragment was identified from the standard picoplankton Euglena gracilis, the tissues of bodies died from drowning and water samples from the drowning scenes. On the other hand, no PCR products were found in the tissues of individuals who died from causes other than drowning. Various quantities of tissue weighing 1, 5, 10, 20 and 30 mg were tested, and the PCR amplification detected the specific16S rDNA fragment from all the quantities of tissue tested. This method was found to be more reliable, sensitive, specific and rapid when compared to the conventional diagnosis of death by drowning using the diatom test by acid digestion method.

Estimation of postmortem interval from rectal temperature by use of computer (III)--thermal conductivity of the skin.

The postmortem rectal temperature fall is the most reliable objective finding for estimation of the postmortem interval within one or two days. However, the thermal properties of human corpses are little known when applying the heat transmission theory to the temperature fall of a human corpse, which is assumed theoretically to be an infinite cylinder. Therefore, the thermal conductivity of excised human skin was measured by the transient hot-wire method. The values in 12 specimens averaged 0.30 Kcal/m.h.°C. The theoretical error due to the experimental conditions such as the size of specimen or heating probe was within about five per cent, and the deviation of three measurements for each material was slight. Accordingly, the deviation of thermal conductivity in 12 materials was considered to be due to the individual disparity in age, sex and postmortem changes.

Short Tandem Repeat Polymorphism of the D2S1242 Locus in a Japanese Population

Allele frequencies and sequence characteristics of the D2S1242 short tandem repeat (STR) locus were studied in a Japanese population sample. A total of 10 D2S1242 alleles and 34 genotypes were identified in 273 unrelated Japanese individuals. The five most common alleles detected had frequencies of over 10%. No deviations from Hardy-Weinberg equilibrium were found when the expected allele values were compared with the observed values. Sequence analysis of each allele showed a tetranucleotide polymorphism. Alleles 9 to 14 had different sequence structures than alleles 15 to 19. Allele 18 had a different sequence in the Japanese sample compared to an Austrian sample. The power of discrimination was 0.95. The present results demonstrate that the D2S1242 STR locus is a useful genetic marker in the Japanese population.

Production of carbon monoxide in cadavers.

Carbon monoxide (CO), total hemoglobin (Hb) and carboxyhemoglobin (HbCO) in the blood and reddish discolored body cavity fluids of cadavers which had not been exposed to fire and CO were analyzed. In 13 cadavers found on land, the maximum saturation of HbCO in the blood was 3.6%, and was 10.1% in the body cavity fluids. There was only one case in which the HbCO saturations in the body cavity fluids were more than 10%. In seven drowned bodies found in fresh water, the highest HbCO saturation in the blood was 6.1%, and was 44.1% in the body cavity fluids. There were three cases in which the HbCO saturations in the body cavity fluids were more than 10%. In 12 drowned bodies found in sea water, the HbCO saturations in the blood were not more than 6.2%, and the maximum saturation of HbCO in the body cavity fluids was 83.7%. There were eight cases in which the HbCO saturations in the body cavity fluids were more than 10%. The results seem to indicate that the interpretation of HbCO saturation in the blood would not be affected significantly by the postmortem formation of CO, and that body cavity fluids should not be used for CO determination.

Transferrin (Tf) polymorphism: An analysis by isoelectric focusing

The polymorphism of the transferrin (Tf) system was studied in a total of 300 unrelated Japanese individuals from Miyagi prefecture, the northern part of Japan using isoelectric focusing in thin-layer polyacrylamide gel. In our population samples three common phenotypes and nine variants were observed. The calculated allele frequencies were TfC1 = 0.773, TfC2 = 0.212, TfDchi (Chinese) = 0.008, and the combined frequencies for the TfBvar (variants) = 0.007. Family data (n = 44) were in accordance with an autosomal codominant fashion of inheritance. The use of isoelectric focusing procedure among Japanese will raise the probability of excluding a man falsely accused of paternity to 15.8% as compared with 1.5% when the conventional electrophoretic methods are used.

Individual identification by DNA polymorphism using formalin‐fixed placenta with whole genome amplification

Polymerase chain reaction (PCR) amplification using formalin‐fixed material is very limited. In the present study the use of 6 week formalin‐fixed placenta for individual identification was examined based on DNA analyses. The objective of the examination was to prove whether the placenta was from a woman who had just given birth. DNA extraction was carried out from the maternal blood sample and from the formalin‐fixed placental samples composed of three parts: maternal side, infant side and umbilical cord. One minisatellite (D1S80), 12 short tandem repeat (STR) polymorphisms and amelogenin X, Y were investigated. All the polymorphic systems were detected in the maternal blood sample. The majority of the DNA isolated from the placental tissues had molecular weights of approximately 500 bp, and only two to four STR loci were amplified using the DNA. In order to amplify more DNA polymorphic markers from the formalin‐fixed tissues, whole genome amplification was performed. After amplification by degenerate oligonucleotide‐primed PCR (DOP‐PCR), the products contained DNA with increased molecular weight up to >10 kbp. More DNA loci were typed using the DOP‐PCR products. Furthermore, large molecular size fragments were purified from the DOP‐PCR products by agarose electrophoresis, and then the D1S80 locus and 12 STR loci were successfully amplified using these fragments.

Frequency of D1S80 and HLA DQα alleles in a Chinese population

Allele frequency distributions for the D1S80 (MCT118) and HLA DQα loci were determined in a Chinese population sample using the polymerase chain reaction (PCR). A total of 25 alleles and 100 phenotypes were observed for D 1 S80. The frequency of allele 18 was higher than allele 24 only in this Chinese population when compared to other reported populations. A total of 6 alleles and 21 possible phenotypes were observed for HLA DQα. The power of discrimination was 0.97 and 0.93 for D1S80 and HLA DQα, respectively.