Inhibitory Effects of the Heat-Killed Lactic Acid Bacterium Enterococcus faecalis on the Growth of Porphyromonas gingivalis.

Background: Porphyromonas gingivalis, a gram-negative obligate anaerobic bacterium, is a major pathogen involved in the onset and progression of periodontal disease, a chronic inflammatory disorder observed in approximately two-thirds of the Japanese population older than age 30 years. P gingivalis cells produce and secrete gingipain, a powerful proteolytic enzyme, on their surfaces and in external environments. Objectives: The effects of heat-killed Enterococcus faecalis (HkEf), a lactic acid bacterium, on the growth of P gingivalis were evaluated in vitro by measuring the viable cell count of P gingivalis and gingipain activity. Methods: HkEf solution (1.63 or 163 mg/mL) was added to 1 mL P gingivalis culture to generate a final HkEf concentration of 0.64 or 64 mg/mL. The cultures were incubated anaerobically. The number of viable P gingivalis cells and gingipain activity were measured after incubation for 0, 12, 24, 48, and 72 hours. The number of viable P gingivalis cells was calculated by counting the number of colonies after culture. Gingipain activity was quantified by adding a chromogenic substrate to P gingivalis culture medium and measuring the absorbance of the reaction solution with a plate reader. Mean (SE) was calculated for viable cell counts and gingipain activity, and Wilcoxon rank-sum test was used to test for significant differences. Results: The counts of viable P gingivalis cells in the control group increased as incubation time progressed for 12, 24, 48, and 72 hours; similar results were observed in the low-concentration HkEf group. In the high-concentration HkEf group, the increase in the viable cell count was significantly inhibited compared with that of the control group. Furthermore, gingipain activity in the low- and high-concentration HkEf groups was significantly inhibited over time compared with that of the control group. Although the pH of the culture solution tended to decrease in the high-concentration HkEf group, it was not considered to have affected the growth of P gingivalis. Conclusions: HkEf exhibits inhibitory effects on the growth of P gingivalis and gingipain activity.

Blood-derived exosomes released after the oral administration of heat-killed Enterococcus faecalis activate immunity.

We aimed to examine the mechanism of heat-killed Enterococcus faecalis (HkEf) immunostimulatory effect when orally administered. Immunocompetent splenocytes from mice orally administered HkEf were assessed using flow cytometry. Immunocompetent cells were determined by culturing splenocytes with serum or blood derived-exosomes. In vitro studies evaluated the reaction between mouse splenocytes and exosomes purified and isolated from mice bone marrow-derived macrophages (BMDMs) treated with HkEf. Levels of dendritic cells, red pulp macrophages, and inactive NK cells were significantly higher in the HkEf-treated group. Red pulp macrophages and inactive NK cells were increased in splenocytes cultured with blood-derived exosomes from mice administered HkEf. Further, mouse splenocytes cultured with the HkEf-stimulated BMDMs-derived exosomes group had significantly higher levels of red pulp macrophages. Thus, HkEf was involved in host immunostimulation and exosomes were identified as mediators in immune response signaling. Further verification of the mechanism would be needed to fill in the gap between the present results and conclusions.

Raman Imaging Analysis of Local Crystal Structures in LiCoO2 Thin Films Calcined at Different Temperatures.

Local crystalline structures of LiCoO2 nanothin film cathodes in a lithium ion battery have been spectroscopically elucidated through confocal Raman imaging analysis at high spatial resolution of several hundred nanometers. A significant difference in the crystalline structure is found between the nanometric thin films and bulk powders. Thermally induced local decomposition of LiCoO2 into an impurity phase on the films has also been revealed along with the mechanism of the temperature-triggered decomposition process. Moreover, frequency-based Raman imaging enables us to locally probe spatial separation between stoichiometric (LiCoO2) and non-stoichiometric (Li1-xCoO2, 0 < x < 1) crystal phases on the thin films. Such local crystalline analysis is a promising approach to provide new insights into the degradation mechanism of lithium-ion batteries, which would result in improving the performance of thin film-based lithium ion batteries.

Novel biogenic aggregation of moss gemmae on a disappearing African glacier.

Tropical regions are not well represented in glacier biology, yet many tropical glaciers are under threat of disappearance due to climate change. Here we report a novel biogenic aggregation at the terminus of a glacier in the Rwenzori Mountains, Uganda. The material was formed by uniseriate protonemal moss gemmae and protonema. Molecular analysis of five genetic markers determined the taxon as Ceratodon purpureus, a cosmopolitan species that is widespread in tropical to polar region. Given optimal growing temperatures of isolate is 20-30 °C, the cold glacier surface might seem unsuitable for this species. However, the cluster of protonema growth reached approximately 10 °C in daytime, suggesting that diurnal increase in temperature may contribute to the moss's ability to inhabit the glacier surface. The aggregation is also a habitat for microorganisms, and the disappearance of this glacier will lead to the loss of this unique ecosystem.

Successfully treated idiopathic rectosigmoid perforation 7 years after renal transplantation.

Colon perforation (CP) is still a critical complication after renal transplantation (RT), and idiopathic perforation is extremely rare. Here we describe a successfully treated case of idiopathic rectosigmoid perforation that occurred 7 years after RT. In our research this is the tenth reported case of idiopathic CP after RT and the second case that has occurred in the rectosigmoid. The patient was a 51-year-old Japanese male RT recipient still receiving immunosuppressive medication. He was admitted to the hospital for sudden onset of abdominal pain during defecation. Emergency laparotomy was performed 5 h after the onset, and a longitudinal 1.5 cm perforation with a clear margin was observed in the rectosigmoid, 8 cm above the peritoneal reflection. Hartmann's operation was performed. Macroscopic and histological examination did not reveal any specific findings that may have caused perforation, so the case was diagnosed as idiopathic rectosigmoid perforation.