Pharmacologic protection of perfused rat heart against global ischemia

Using a Langendorff rat heart model, studies were performed on the effects of three drugs in protecting the heart against global ischemia. The drugs used were: (a) MR-256, a prostaglandin oligomeric derivative, which is a calcium chelating agent and at the same time, is an inhibitor of phospholipase A2 activity, (b) chlorpromazine which is not a calcium chelator, but is a calmodulin antagonist and is an inhibitor of phospholipase A2 activity, and (c) BAPTA/AM, a calcium chelating agent, but which is not an inhibitor of phospholipase A2 activity. The perfused heart was exposed to 15 minutes of global ischemia. In control experiments (no drug), the ventricular pressure recovered to 26.4 +/- 6.7% (n = 22) of the original level. With pretreatment of (a) MR-256 (b) chlorpromazine, and (c) BAPTA/AM, maximum recoveries were 0.5 +/- 6.7% (n = 5), 88.7 +/- 8.5% (n = 5), 45.3 +/- 26.6% (n = 5), respectively. MR-256 and chlorpromazine were found to react with free radicals. The modes of action of these three different types of drugs are discussed.     

Protection of the heart from ischemia by a new oligomeric derivative of prostaglandin E1

A lipophilic oligomeric ester was synthesized from prostaglandin E1. The compound was found to protect a Langendorff perfused rat heart from ischemic insult. After 15 minutes cessation of perfusion, the flow was restarted, and the recovery of contraction was measured. In control experiments, the recovery was 16.1 +/- 7.3%. In the case of pre-ischemic addition of the compound (10 micrograms/ml at 10 minutes before ischemic insult), the recovery was 31 +/- 13.2% (n = 7; the difference was not significant). In post-ischemic addition (10 micrograms/ml), the recovery was 75.9 +/- 9.0% (n = 7; p less than 0.01). The compound was also effective in protecting rat heart myocytes against a 60 minutes anoxia/15 minutes reoxygenation injury as judged by the loss of "rod-shaped" intact myocytes. At a 10 micrograms/ml concentration, the compound protected against the loss of rod-shaped myocytes by 30% in pre-anoxia addition and 35% in post-anoxia addition. The levels of significance in these experiments were p less than 0.001. Possible mechanisms of action of this compound are discussed.     

Application of the chloroform fumigation-incubation method to the estimation of soil microbial biomass in burned and unburned Japanese red pine forests

Abstract Estimation of soil microbial biomass in burned and unburned Japanese red pine forests was attempted using the chloroform fumigation-incubation method. As the amount of CO₂-C evolved from the fumigated soil for 10–20 days after fumigation (designated as F') was always lower than that from the unfumigated soil during the same period (UF'), the formula, microbial biomass-C(M) = the amount of CO₂-C evolved from the fumigated soil for 0–10 days after fumigation, F) − F'/ k _c, was proposed instead of Jenkinson's conventional formula, M = (F − UF')/ k _c. The k _c value was also determined as 0.30 using 3 fungal and 3 bacterial cultured species as internal standards. Microbial biomass-C calculated by (F − F')/0.30 decreased with soil depth at both the burned (Nenoura, 3.5 years after fire) and unburned (Ato) sites, showing the significant correlation with the decrease of soil respiration and organic C content along soil depth. Microbial biomass-C in the 0–2 cm soil layer at the burned site at Nenoura was 130 mg/100 g dry soil and those in the HF horizon and 0–2 cm soil layer at the unburned site at Ato were 686 and 146 mg/100 g dry soil, respectively.     

Isolated lymphoid follicles are not IgA inductive sites for recombinant Salmonella

In this study, we investigated whether isolated lymphoid follicles (ILF) play a role in the regulation of intestinal IgA antibody (Ab) responses. The transfer of wild type (WT) bone marrow (BM) to lymphotoxin-alpha-deficient (LTalpha(-/-)) mice resulted in the formation of mature ILF containing T cells, B cells, and FDC clusters in the absence of mesenteric lymph nodes and Peyer's patches. Although the ILF restored total IgA Abs in the intestine, antigen (Ag)-specific IgA responses were not induced after oral immunization with recombinant Salmonella expressing fragment C of tetanus toxin. Moreover, Ag-specific cell proliferation was not detected in the ILF. Interestingly, no IgA anti-LPS Abs were detected in the fecal extracts of LTalpha(-/-) mice reconstituted with WT BM. On the basis of these findings, ILF can be presumed to play a role in the production of IgA Abs, but lymphoid nodules are not inductive sites for the regulation of Ag-specific intestinal IgA responses to recombinant Salmonella.     

Self‐quenching in the electrochemiluminescence of Ru(bpy)32+ using ascorbic acid as co‐reactant

In this study, electrochemiluminescence (ECL) of Ru(bpy)₃²⁺ (bpy = 2,2′‐bipyridyl) using ascorbic acid (H₂A) as co‐reactant was investigated in an aqueous solution. When H₂A was co‐existent in a Ru(bpy)₃²⁺‐containing buffer solution, ECL peaks were observed at a potential corresponding to the oxidation of Ru(bpy)₃²⁺, and the intensity was proportional to H₂A concentration at lower concentration levels. The formation of the excited state *Ru(bpy)₃²⁺ was confirmed to result from the co‐reaction between Ru(bpy)₃³⁺and the intermediate of ascorbate anion radical (A⁻•), which showed the maximum ECL at pH = 8.8. It is our first finding that the ECL intensity would be quenched significantly when the concentration of H₂A was relatively higher, or upon ultrasonic irradiation. In most instances, quenching is observed with four‐fold excess of H₂A over Ru(bpy)₃²⁺. The diffusional self‐quenching scheme as well as the possible reaction pathways involved in the Ru(bpy)₃²⁺–H₂A ECL system are discussed in this study. Copyright © 2008 John Wiley & Sons, Ltd.     

Heterogeneity of pluripotent marker gene expression in colonies generated in human iPS cell induction culture

Induction of pluripotent stem cells from human fibroblasts has been achieved by the ectopic expression of two different sets of four genes. However, the mechanism of the pluripotent stem cell induction has not been elucidated. Here we identified a marked heterogeneity in colonies generated by the four-gene (Oct3/4, Sox2, c-Myc, and Klf4) transduction method in human neonatal skin-derived cells. The four-gene transduction gave a higher probability of induction for archetypal pluripotent stem cell marker genes (Nanog, TDGF, and Dnmt3b) than for marker genes that are less specific for pluripotent stem cells (CYP26A1 and TERT) in primary induction culture. This tendency may reflect the molecular mechanism underlying the induction of human skin-derived cells into pluripotent stem cells. Among the colonies induced by the four-gene transduction, small cells with a high nucleus-to–cytoplasm ratio could be established by repeated cloning. Subsequently established cell lines were similar to human embryonic stem cells as well as human induced pluripotent stem (iPS) cells derived from adult tissue in morphology, gene expression, long-term self-renewal ability, and teratoma formation. Genome-wide single-nucleotide polymorphism array analysis of the human iPS cell line indicates that the induction process did not induce DNA mutation.     

Prostaglandin derivatives inhibit the growth of malarial parasites in mice

New prostaglandin oligomeric derivatives, termed MR-256 and MR-356, were found to inhibit the growth of murine malarial parasites, P. chabaudi and P. vinckei, within red blood cells in vivo. When mice were infected with P. chabaudi, both MR-256 and MR-356 suppressed the growth of parasites, but MR-356 had a greater inhibitory effect than MR-256. With P. vinckei, MR-356 also inhibited the growth of parasites, and improved the survival rate. The effect of MR-256 was much less. A possible inhibitory mechanism of action of these drugs is discussed.     

Generation carryover of a fraction of population members as an animal adaptation to unstable environmental conditions

Summary A heterogeneous life cycle of individuals in a population was examined on its adaptive significance to an unstable environmental condition. The trend of population growth was simulated by a simple mathematical model in which a part of population in a certain generation was carried over to the next generation without participating in the reproduction. With the increase of the rate of carryover of individuals to the next generation the population fluctuation tended to be stabilized. A minute fraction of population is carried over, the effect is very large to prevent the population decline at a sequence of adverse environmental conditions. The population level increased greatly depending upon the extent of environmental change as far as the rate of carryover took an intermediate value. The optimum proportion of members to be carried over to the next generation was determined by the extent of environmental change and its frequency of occurrence. Contribution from the Entomological Laboratory, College of Agriculture, Kyoto University, No. 451.