Hiroyasu Yoshikawa

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A rosette plant of Eustoma grandiflorum requires vernalization (exposure to a period of cold temperature) and long-day conditions to promote flowering, while prolonged cold or cool temperatures in post-vernalization periods delay flowering. This study aimed to investigate the effect of growth conditions on flowering regulation in Eustoma. In Arabidopsis,(More)
Epidemiological studies associate smoking with reduced insulin secretion. We hypothesized that nicotine could negatively affect pancreatic beta-cell function. Acute or 48-hour exposures to nicotine (10(-4) to 10(-6) mol/L) moderately inhibited insulin release at basal (3.3 mmol/L) and/or elevated (27 mmol/L) glucose in rat and human islets. Acute exposure(More)
An automatic feeding process for microbial hydroxylation of ML236B sodium salt (ML-236B Na; compactin) by Streptomyces carbophilus SANK 62585 was developed. The hydroxylated product, pravastatin sodium salt (pravastatin; trade name Mevalotin), is an inhibitor of 3-hydroxy-3-methyglutaryl-coenzyme A reductase (HMG-CoA reductase) used as cholesterol-lowering(More)
INTRODUCTION The mechanism for beta-cell dysfunction induced by glucosamine has not yet fully been investigated previously. AIM To investigate the effects of glucosamine on insulin release or gene expression related to glucose metabolism in rat islets cultured with glucosamine for 24 hours. METHODOLOGY After islets were cultured with glucosamine or(More)
Prolonged periods of "beta-cell rest" exert beneficial effects on insulin secretion from pancreatic islets subjected to a high-glucose environment. Here, we tested for effects of short-term intermittent rest achieved by diazoxide. Rat islets were cultured for 48 h with 27 mmol/l glucose alone, with diazoxide present for 2 h every 12 h or with continuous(More)
Regulation of uncoupling protein-2 (UCP-2) in beta-cells is presently unclear but may involve oxidative stress. We tested for regulation by beta-cell toxic cytokines. Exposure to interleukin-1beta (IL-1beta, 10 ng/ml) for 6 h down-regulated UCP-2 mRNA in clonal INS-1 cells, by 37 +/- 7%, and in rat pancreatic islets, by 55 +/- 8%. In contrast, a 6 h(More)
Yoshikawa, Hiroyasu, Zuheng Ma, Anneli Björklund, and Valdemar Grill. Short-term intermittent exposure to diazoxide improves functional performance of -cells in a high-glucose environment. Am J Physiol Endocrinol Metab 287: E1202–E1208, 2004. First published August 3, 2004; doi:10.1152/ajpendo.00255.2004.—Prolonged periods of “ -cell rest” exert beneficial(More)
Of the acyl th ioder ivat ives (Acyl. S.D.) which have been recognized as in te rmedia tes in the f a t t y acid de novo synthes is and oxidation, were studies wi th the G. L. C, analysis in var ious hormonal and nut r i t iona l condit ions such as hypophysectomy, adrenalectomy, subtotal pancleatec tomy or replacement of ACTH, glucocorticoid and insul in(More)