Effect of Fatty Acids on the Membrane Potential of an Alkaliphilic <Emphasis Type="Italic">Bacillus</Emphasis>

Effect of various fatty acids on the membrane potential of an alkaliphilic Bacillus, YN-2000, was examined. Addition of unsaturated fatty acids such as palmitoleic acid, oleic acid, linoleic acid, and linolenic acid at 30 M caused the instantaneous depolarization of the membrane potential of the bacterium, which appears to result in the drastic decrease of viability. On the other hand, no depolarization was detected by the addition of saturated acids such as palmitic acid, stearic acid, and 12-hydroxystearic acid even at 1 mM.     

Immunogenicity of inactivated seasonal influenza vaccine in adult and pediatric liver transplant recipients over two seasons

Immunological responses to influenza vaccination administered to liver transplantation recipients are not fully elucidated. To compare inactivated influenza vaccine's immunogenicity between adult and pediatric recipients, 16 adult and 15 pediatric living donor liver transplantation recipients in the 2010–11 influenza season, and 53 adult and 21 pediatric recipients in the 2011–12 season, were investigated. Seroprotection rates (hemagglutinin‐inhibition [HI] antibody titer 1:40) were 50–94% to all three antigens among adults and 27–80% among children in both seasons. Seroconversion rates (fourfold or more HI antibody rise) were 32–56% among adults and 13–67% among children in both seasons. No significant differences were observed between the two groups. In addition, 20/53 adult and 13/21 pediatric recipients received a vaccine containing identical antigens in both of these seasons. Geometric mean titer fold increases of all three antigens in adult recipients were significantly lower than those in recipients who had not received a preceding vaccination. In contrast, in pediatric recipients, there were no significant differences between the groups who had and had not received preceding vaccinations. The number of patients with rejection did not differ significantly between the two groups (0/53 vs. 1/21) in the 2011–12 season. The incidence of influenza after vaccination was significantly different between adult and pediatric recipients (0/16 vs. 5/15 in 2010–11 and 0/53 vs. 3/21 in 2011–12, respectively). Overall, there were no significant differences in antibody responses between adult and pediatric groups. Influenza infection was more frequent in pediatric recipients. Long‐term response to preceding vaccinations appeared to be insufficient in both groups.     

Syntheses of Unsaturated Lactones

Homologous unsaturated δ-lactones were prepared and the nature of their flavors was investigated. Among those, lactones of 5-hydroxy-2-decenoic acid and 5-hydroxy-8-methyl-2-nonenoic acid were shown to have a flavor the most similar to a butter or butter cake flavor.     

Acetoacetate Decarboxylase and a Peptide with Similar Activity Produced by Bacillus polymyxa A-57

Acetoacetate decarboxylase is a valuable tool for clinical analysis of ketone bodies in human plasma. After screening many microorganisms, we found Bacillus polymyxa A-57 to be a new enzyme source with a good yield of acetoacetate decarboxylase. After purifying the intracellular enzyme by three-stage column chromatography, we identified it as a single protein by SDS-polyacrylamide gel electrophoresis. The enzyme had a molecular weight of approximately 280,000 and consisted of 10 (±2) identical subunits. It had an optimum pH of 5.9 and was stable up to about 60°C for 30min. The apparent Km and V_max values for lithium acetoacetate were 0.94 mm and 296 μmiol/min/mg, respectively. In addition, the decarboxylase activity was found in the broth. After purification, we found that it was due to an active peptide which we named A-57-9, which we identified as the antibiotic polymyxin M₁. However, the V_max value (0.25 μmol/min/mg) of the peptide was very much lower and the Km value (400 mm) was higher than those of real acetoacetate decarboxylase.     

Essential role of extrathymic T cells in protection against malaria

Athymic nude mice carry neither conventional T cells nor NKT cells of thymic origin. However, NK1.1(-)TCR(int) cells are present in the liver and other immune organs of athymic mice, because these lymphocyte subsets are truly of extrathymic origin. In this study, we examined whether extrathymic T cells had the capability to protect mice from malarial infection. Although B6-nu/nu mice were more sensitive to malaria than control B6 mice, these athymic mice were able to survive malaria when a reduced number of parasitized erythrocytes (5 x 10(3) per mouse) were injected. At the fulminant stage, lymphocytosis occurred in the liver and the major expanding lymphocytes were NK1.1(-)TCR(int) cells (IL-2Rbeta(+)TCRalphabeta(+)). Unconventional CD8(+) NKT cells (V(alpha)14(-)) also appeared. Similar to the case of B6 mice, autoantibodies (IgM type) against denatured DNA appeared during malarial infection. Immune lymphocytes isolated from the liver of athymic mice which had recovered from malaria were capable of protecting irradiated euthymic and athymic mice from malaria when cell transfer experiments were conducted. In conjunction with the previous results in euthymic mice, the present results in athymic mice suggest that the major lymphocyte subsets associated with protection against malaria might be extrathymic T cells.     

Chemical synthesis of a human fibroblast interferon gene and its expression in Escherichia coli

Using the solid phase phosphotriester method, a gene coding for human fibroblast interferon consisting of 166 amino acid residues was chemically synthesized. The gene obtained by ligation of 61 synthesized oligodeoxyribonucleotide fragments was inserted into the downstream of tryptophan promoter, and expressed in E. coli. Lysate of this E. coli showed the antiviral activity which was specifically neutralized by anti-fibroblast interferon antibody. No particular advantage was observed in the expression efficiency by the synthetic gene over that by the native gene.