K. C. Yamada

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Organisms prefer to receive rewards sooner rather than later because they excessively discount the subjective value of future rewards, a phenomenon called delay discounting. Recent studies have reported an association between cortisol-which is secreted by the hypothalamic-pituitary-adrenal (HPA) axis-and delay discounting. However, no study has examined(More)
The purpose of the present study was to examine Hypothalamus-Pituitary-Adrenal (HPA) axis reactivity in social anxiety. The present study used a standardized psychosocial stress protocol (the Trier Social Stress Test; TSST; [Kirschbaum, C., Pirke, K.M., Hellhammer, D.H., 1993. The 'Trier Social Stress Test'-a tool for investigating psychobiological stress(More)
We investigated dehydroepiandrosterone (DHEA) secretion in response to acute psychosocial stress and the relations of DHEA secretion to cortisol secretion, cardiovascular activity, and negative mood changes. Thirty-three male students (mean age 22.6 years) were subjected to the psychosocial stress test "Trier Social Stress Test" (TSST), in which the(More)
Although interleukin-6 (IL-6) has been investigated frequently in stress research, knowledge regarding the biological processes of IL-6 in association with psychosocial stress remains incomplete. This study focused on salivary IL-6 and reports its temporal variation and biological correlates following acute psychosocial stress. Fifty healthy young adults(More)
BACKGROUND/AIMS Protein kinase C (PKC) is well-recognized to modify ligand-gated ion channels such as nicotinic ACh (nACh) receptors by phosphorylating the receptors. The aim of the present study was to obtain direct evidence for PKC activation through nACh receptors. METHODS Two-electrode voltage-clamp was made to Xenopus oocytes expressing wild-type and(More)
Cortisol secretion after awakening, an index of hypothalamus-pituitary-adrenal axis activity, appears to be related to psychosocial stressors, or to symptoms caused by psychosocial stressors. The relationship between the quality, duration, and magnitude of psychosocial factors and cortisol secretion is however, unclear. Therefore, the effect of episodic(More)
PURPOSE To evaluate the risk factors for bowel necrosis in adult patients with hepatic portal venous gas (HPVG). METHODS This retrospective study comprised 33 adult patients treated for HPVG between August, 2008 and December, 2011. The patients were divided into a necrotic group (n = 14) and a non-necrotic group (n = 19). We analyzed the clinical(More)
OBJECTIVE In this study, we investigated levels and relative ratios of adrenal hormones (including cortisol, dehydroepiandrosterone [DHEA], and DHEA-sulfate [DHEA-S]) and their psychophysiological correlates under acute psychosocial stress in individuals with irritable bowel syndrome (IBS). METHODS Fifty-three college students participated in the study(More)
INTRODUCTION The hypothalamic-pituitary-adrenal axis is known to be related to abdominal symptoms, and the relationship between abdominal pain and cortisol secretory patterns has been previously investigated using a cross-sectional approach. Here, we investigated the effect of day-to-day variations in salivary cortisol and dehydroepiandrosterone-sulfate(More)
Hyperinsulinemia associated with type 2 diabetes may contribute to the development of vascular diseases. Although we recently reported that enhanced contractile responses to serotonin (5-hydroxytryptamine, 5-HT) are observed in the arteries of type 2 diabetes models, the causative factors and detailed signaling pathways involved remain unclear. The purpose(More)