Jun Ohta

In forensic saliva testing, false negatives of the Phadebas® and false positives of the RSID™‐saliva methods generated by citric acid are critical issues for interpreting the results. Citric acid‐containing beverages, which are typically mixed with forensic saliva samples, may produce indistinguishable results in two commercially available saliva tests in the presence and absence of saliva. To solve this issue, this study aimed to evaluate the usefulness of the indirect enzyme‐linked immunosorbent assay (ELISA)‐based method of detecting cystatin D to identify saliva in citric acid‐containing beverage‐mixed samples. Four commercially available beverages were mixed with human saliva or ultrapure water, and the mixed stain samples were examined by the aforementioned three saliva tests. Two conventional saliva tests could not distinguish between the samples with and without saliva. Although the positive detection rates of the ELISA method decreased when mixed with beverages, no saliva‐free beverage samples produced false positives. Our results indicate that the detection of cystatin D by indirect ELISA would be useful in identifying saliva from samples potentially mixed with citric acid‐containing beverages.

Analyzing forensically relevant body fluids contributes to proving criminal acts, and saliva is often left on the scene, especially in sexual assault cases.

The pink teeth phenomenon has occasionally been observed in forensic autopsies. This study aimed to establish an experimental pink tooth model and an objective color tone evaluation method in order to clarify changes in the color tone of teeth and the relationship with hemoglobin monoxide and its decomposition products and with red pigment-producing bacteria, under various external environmental factors. It was confirmed that the color tone evaluation with ΔE and the L*C*h color space was useful. The results of various examinations using this model showed that color development was suppressed under aerobic conditions, faded early under light, became bright red under a low temperature and showed a tendency to be reddish at 3 days under high humidity and in the presence of soft tissue. The biochemical analysis revealed a significant increase in carboxyhemoglobin at 7 days and a tendency toward increasing the total heme pigment and bilirubin levels over time. The bacteriological analysis revealed that red pigment-producing bacteria increased over time but that the color faded after 7 days. These results suggest that putrefaction greatly affects the pink teeth phenomenon, whereas red pigment-producing bacteria have little effect on the occurrence of pink teeth. However, further studies are needed to clarify bacteriological involvement.

This study sought to clarify the characteristics and trends of physical elder abuse and the status of collaboration between forensic medicine departments and related institutions in Japan. Questionnaires were sent to 82 forensic medicine departments and 2857 institutions randomly selected from hospitals, municipalities and public community general support centers. The survey period was February to June 2021, including an extension period for collection. Responses from 675 facilities were analyzed. The most common finding in cases of physical elder abuse at forensic medicine departments was subcutaneous hemorrhage on the head (85.7%), with mixed old and new injuries most commonly observed in the lower limbs (70%). There were few cases in which there was collaboration between forensic medicine departments and other institutions. Among the issues identified, there is a need to provide related institutions with information obtained in forensic medicine departments. A new collaboration system is needed to achieve this.

The pink teeth phenomenon has been observed in cases of hanging and drowning, but the relationship of this phenomenon with cause of death has not been positively affirmed. To date, teeth with a pinkish tone have been simply regarded as pink teeth. However, we speculated that classification and evaluation of the degree and region of discoloration with reference to how color is classified in prosthodontic dentistry may produce novel findings regarding the pink teeth phenomenon. Therefore, we classified the degree and region of discoloration on teeth into three grades and attempted to evaluate the relationship of grade with various cadaveric factors in 68 cases of pink teeth. The degree and region scores of discoloration did not show significant differences in terms of sex, age, cause of death, and place of discovery, but the degree of discoloration in terms of time after death showed a significant increase at 6 months (p < 0.01) and a significant decrease after 7 months (p < 0.05), while the region score also showed a significant decrease after 7 months. Furthermore, in 18 cases of drowning, the degree of discoloration significantly increased with time after death (p < 0.01). Thus, it was clarified that time after death was most strongly related to the pink teeth phenomenon, suggesting cadaveric decomposition may affect the occurrence of pink teeth. Further investigation in cases of early postmortem changes would be required to determine whether pink teeth in putrefactive cadavers have utility in medico–legal assessments.

The Calvin–Benson cycle (CB cycle) is quantitatively the most important metabolic pathway for CO₂ fixation. In the canonical CB cycle, fructose 6-phosphate (F6P), fructose 1,6-bisphosphate (FBP), sedoheptulose 7-phosphate (S7P), and sedoheptulose 1,7-bisphosphate (SBP) appear as essential intermediates, where F6P is formed from FBP by the fructose 1,6-bisphosphatase (FBPase) reaction, and S7P is formed from SBP by the sedoheptulose 1,7-bisphosphatase (SBPase) reaction. Although the involvement of SBP and SBPase in the canonical CB cycle is consistent with the reported dependency of photosynthetic carbon metabolism on SBPase, the involvement of FBP and FBPase is not completely consistent with the reported FBP- or FBPase-related findings such as, although with a diminished growth rate, an Arabidopsis mutant lacking FBPase grew photoautotrophically in soil. Here, we show a novel variant of the CB cycle involving SBP, SBPase, and transaldolase, but neither FBP nor FBPase. This novel variant, named the S7P-removing transaldolase variant, bypasses FBP. This variant explains the FBP- or FBPase-related findings more easily than the canonical CB cycle as well as the dependency of photosynthetic carbon metabolism on SBPase and further suggests that co-overexpression of SBPase and transaldolase can be a strategy for enhancing photosynthetic carbon metabolism, which is important for the global environment.