[Evaluation of the Capacity to Produce Histamine by Histamine-Producing Bacteria during Storage at 10℃].

Histamine is produced from histidine using histidine decarboxylase of histamine-producing bacteria. However, associated histamine food poisoning demands microbiological controls. Furthermore, studies reported that histamine production by histamine-producing bacteria is affected by temperature. Therefore, to prevent histamine food poisoning, it is desirable to store foods below 4℃. However, it is challenging to maintain the storage temperature of food substances in refrigerators constantly below 4℃. Thus, we investigated histamine production capacity using seven histamine-producing bacterial strains under storage at 10℃, a more reasonable cold storage condition. Subsequently, we examined the variation of histamine production in buffers, the correlation between bacterial density and histamine production quantities, and the growth rate in broths. Results showed that similar levels of histamine were produced in buffers even after 5 days of storage under certain conditions in which histamine-producing bacteria did not grow. Moreover, bacterial density was proportional to histamine production, and the coefficient of determination was more than 0.97, and the bacterial density required to produce 200 µg/mL of histamine during storage at 10℃ was calculated to be 4×107-4×108 CFU/mL. When the initial bacterial density was 102-103 CFU/mL, psychrophilic bacteria required 2 or 3 days and mesophilic bacteria required more than 4 days to grow above 107 CFU/mL. The above results suggest that understanding the capacity of histamine-producing bacteria to produce histamine and its growth rate in foods is important for the prevention of histamine food poisoning.

Occlusal support and postural stability in children: An observational study.

BACKGROUND: The relationship between uneven occlusal contact and fall risk has been described in elderly participants; however, multiple confounding factors, such as systemic disease or deterioration in vestibular function, have not been well considered. This study aimed to investigate this relationship in pediatric participants at the age of approximately 9-12, where these confounding factors are absent and the replacement of primary molars by permanent ones generally occurs and transiently results in uneven occlusal contact. METHODS: Sixty-five children (36 boys and 29 girls, mean age: 9.5 ± 1.5 years) were enrolled in this study. Participants were asked whether they had experienced at least two falls within the past 1 year. The occlusal contact area ratio was calculated by dividing the greater half (right or left dental arch) by the smaller half (the other half) with U-shaped pressure sensor sheet. The total length and rectangular area of the center of pressure while standing upright for 10 s were measured with a stabilometer and used as postural sway parameters. RESULTS: The occlusal contact area ratio significantly correlated with the postural sway parameters. Comparison between those who had experienced the fall incidences and those who had not after propensity score matching that adjusts their overall physical function revealed that there were no significant differences in the postural sway parameters and occlusal contact area ratio regardless of the history of fall incidence. CONCLUSIONS: Uneven occlusal contact leads to an increase in postural sway in children; however, this may not be associated with fall incidence.