Effect of calcium ion on fatty acid-induced generation of superoxide in guinea pig neutrophils

When phospholipases of plasma membranes are activated by certain stimuli, unsaturated fatty acids are liberated. Because unsaturated fatty acids enhance the transmembrane movement of calcium ions, the fatty acids released may modulate intracellular calcium homeostasis in various cells, including neutrophils. To determine the physiological function of these unsaturated fatty acids, we studied the effects of various fatty acids on superoxide generation and on changes in intracellular calcium contents of guinea pig neutrophils. Some unsaturated fatty acids, arachidonate and linoleate, stimulated the rate of superoxide generation concomitant with the increase in the amount of intracellular calcium. In contrast, the saturated fatty acid, myristate, stimulated the generation of superoxide without affecting the content of intracellular calcium. The stimulating actions of arachidonate and myristate were increased dramatically by the presence of a low concentration (1 microM) of extracellular calcium ion. The rate of superoxide generation in fatty acid-treated neutrophils was inhibited by chlorpromazine, an inhibitor of such calcium-binding proteins as C-kinase. These and other observations suggest that liberated unsaturated fatty acids increase the amount of intracellular calcium and enhance C-kinase activity also that the increased activity of the enzyme is involved in the chain of events leading to the stimulation of superoxide generation in fatty acid-treated neutrophils.     

Molecular pathogenesis of malignant melanoma: a different perspective from the studies of melanocytic nevus and acral melanoma

The Clark model for melanoma progression emphasizes a series of histopathological changes beginning from benign melanocytic nevus to melanoma via dysplastic nevus. Several models of the genetic basis of melanoma development and progression are based on this Clark’s multi-step model, and predict that the acquisition of a BRAF mutation can be a founder event in melanocytic neoplasia. However, our recent investigations have challenged this view, showing the polyclonality of BRAF mutations in melanocytic nevi. Furthermore, it is suggested that many melanomas, including acral and mucosal melanomas, arise de novo, not from melanocytic nevus. While mutations of the BRAF gene are frequent in melanomas on non-chronic sun damaged skin which are prevalent in Caucasians, acral and mucosal melanomas harbor mutations of the KIT gene as well as the amplifications of cyclin D1 or cyclin-dependent kinase 4 gene. Amplifications of the cyclin D1 gene are detected in normal-looking ‘field melanocytes’, which represent a latent progression phase of acral melanoma that precedes the stage of atypical melanocyte proliferation in the epidermis. Based on these observations, we propose an alternative genetic progression model for melanoma.     

Polymorphonuclear leukocyte-inhibitory factor of Bordetella pertussis. III. Inhibition of Arthus reaction and peritoneal infiltration of PMN

In vivo biologic effects of the polymorphonuclear leukocyte-inhibitory factor (PIF) of Bordetella pertussis were tested by using two experimentally induced inflammatory processes in mice. The intravenous injection of a partially purified extract from phase I bacteria strongly inhibited the glycogen-induced peritoneal infiltration of polymorphonuclear leukocytes (PMN) and the Arthus reactions, whereas little inhibitory activity was found in the extract from phase III bacteria. The activity was localized in the outer membrane of phase I bacteria, as was the in vitro PIF activity, and the two activities gave the same behavior in DEAE-cellulose chromatography. Therefore the observed suppression of inflammatory processes in mice is probably due to the inhibitory action of PIF on the function of PMN in vivo.     

Kinetic resolution of organosilicon compounds by stereoselective dehydrogenation with horse liver alcohol dehydrogenase

Streoselective dehydrogenation of three isomers of trimethylsilypropanol was carried out with horse liver alcohol dehydrogenase (HLADH, EC 1.1.1.1.) and optically active organosilicon compounds were obtained in a water-organic solvent two-layer system with coenzyme regeneration. Furthermore, we examined the effects of the silicon atom on stereoselectivity of HLADH compared to the corresponding carbon compounds. Substitution of the silicon atom for the carbon atom was found to improve the stereoselectivity of HLADH. For example, the optical purity of the remaining 1-trimethylsilyl-2-propanol was higher than 99% enantiomeric excess (ee) at 50% conversion, whereas that of the carbon analogue was 84% ee. This phenomenon was probably ascribable to the bulkiness of the organosilicon compounds derived from their longer Si-C bond. Kinetic analysis in an aqueous monolayer system demonstrated that the specific properties of the silicon atom greatly affected the reactivity of these substrate compounds.Correspondence to: A. Tanaka     

Salt tolerance and glycerol accumulation of a respiration-deficient mutant isolated from the petite-negative, salt-tolerant yeast Zygosaccharomyces rouxii

A respiration-deficient (RD) mutant was isolated from the petite-negative, salt-tolerant yeast Zygosaccharomyces rouxii. One strain among sixteen glycerol-non-utilizing mutants exhibited vigorous liberation of CO2 but no uptake of O2. Furthermore, this strain lacked cytochrome aa3 and had a reduced level of cytochrome b. The few mitochondria found in cells of this strain contained few or no cristae. Salt tolerance and intracellular accumulation of glycerol by the RD strain were almost equal to that of the wild-type strain in media containing NaCl up to 2.5 M. In media with more than 3 M NaCl, the growth of the RD mutant was retarded and the intracellular accumulation of glycerol was depressed in spite of ample production.     

Impact of Pulsed Nd:YAG Laser Irradiation on the Growth and Mortality of the Biofilm Forming Marine Bacterium Pseudoalteromonas carrageenovora

The impact of pulsed laser irradiation on the marine biofilm forming bacterium Pseudoalteromonas carrageenovora was investigated in the laboratory by monitoring mortality and the post-irradiation growth pattern. The impact of laser irradiation on bacterial mortality increased with the duration of irradiation. Laser irradiation at 532 nm (0.1 J cm m 2 ) for 15 min resulted in a 53% cell mortality immediately after irradiation. However, the impact after a period of 5 h (delayed impact) was more severe. The growth pattern of irradiated samples showed a prolonged lag phase compared to the reference, due to a reduction in total viable counts (TVC) in the irradiated samples. Nucleic acid staining is suggested to be a promising technique for monitoring laser inflicted bacterial mortality. Thus, the results suggest that laser irradiation could be considered as an alternative technique to reduce the number of biofilm forming bacteria and thereby biofilm formation on hard surfaces.