Yasuhiro Kambayashi

c-Kit-Targeting Immunotherapy for Hereditary Melanoma in a Mouse Model

The role of c-Kit in the development of melanoma was studied in line 304/B6 of RET-transgenic mice, in which melanoma spontaneously develops. In Wv/Wv-RET (304/B6)-transgenic mice, in which c-Kit function was severely impaired, development of melanoma was strongly suppressed. Although 31 of the 44 original RET-transgenic mice died of rapidly growing melanoma within 12 months after birth, only 8 of the 44 Wv/Wv-RET-transgenic mice developed slowly growing melanocytic tumors with a greatly prolonged mean tumor-free period, 2 of which died of melanoma at a late stage. Even Wv/+-RET-transgenic mice had a clearly prolonged tumor-free period and definitely reduced frequency (6 of 61) of tumor death within 12 months after birth. Melanin production in the skin of these mice was not strongly impaired, suggesting that c-Kit affects the development of melanomas in these mice with only minor effects in melanin production. c-Kit expression in skin soon after birth was promoted in RET-transgenic mice, and c-Kit was expressed at high levels at the benign but not malignant stage of the tumor. A single injection of anti-c-Kit antibody (ACK2) into RET-transgenic mice soon after birth caused a surprisingly long-lasting suppression of development of melanoma, greatly prolonging the tumor-free period, and none of the 28 ACK2-treated RET-transgenic mice died from tumors at 12 months of age. The c-Kit function needed for melanin production was also suppressed for an unusually long time in ACK2-treated, RET-transgenic mice. These results suggest that c-Kit can be a unique target molecule for melanoma treatment.

Nonthermal effects of mobile-phone frequency microwaves on uteroplacental functions in pregnant rats

Exposure to high-density microwaves can cause detrimental effects on the testis, eye, and other tissues, and induce significant biologic changes through thermal actions. To examine nonthermal effect of continuous wave (CW) 915MHz microwaves used in cellular phones, we compared the effects of microwaves with those of heat. Thirty-six pregnant rats were assigned to six groups: rats exposed to microwaves at 0.6 or 3mW/cm(2) incident power density at 915MHz for 90min, rats immersed in water at 38 or 40 degrees C, which induces about the same increase in colonic temperature of 1.0 or 3.5 degrees C as 0.6 or 3mW/cm(2) microwaves, respectively; rats immersed in water at 34 degrees C, which is considered to be thermoneutral; and control rats. We identified significant differences in the uteroplacental circulation, and in placental endocrine and immune functions between pregnant rats immersed in water at 34 and 38 degrees C, but not between rats immersed at 38 degrees C and those exposed to microwaves at 0.6mW/cm(2). By contrast, we observed significant decreases in uteroplacental blood flow and estradiol in rats exposed to microwaves at 3mW/cm(2) as compared with those immersed in water at 40 degrees C. These results suggest microwaves at 0.6mW/cm(2) at 915MHz, equal to a specific absorption rate (SAR) of 0.4W/kg, which is the maximum permissible exposure level recommended by the American National Standards Institute (ANSI), do not exert nonthermal effects on blood estradiol and progesterone, on splenic natural killer cell activity, on the uteroplacental circulation.

Inactivation of bacterial respiratory chain enzymes by singlet oxygen

To distinguish the bactericidal action of singlet oxygen (1O2) from hypohalous acids, wild‐type and lycopene transformant E. coli strains were exposed to each of the oxidants and then bacterial viability was investigated. 1O2 was generated by chemical and enzymatic systems at pH 4.5. Exposure of wild‐type E. coli to 1O2 caused a significant loss of E. coli viability due to inactivation of membrane respiratory chain enzymes by 1O2. This action of 1O2 could be attenuated by lycopene in the bacterial cell membrane. In the lycopene transformant strain of E. coli, inactivation of NADH oxidase and succinate oxidase by hypohalous acids were significantly suppressed, but E. coli viability was unaffected. Based on these findings, we suggest that phagocytic leukocytes produce 1O2 as a major bactericidal oxidant in the phagosome.

Health impact of disaster‐related stress on pregnant women living in the affected area of the Noto Peninsula earthquake in Japan

Aims:  The present study assessed the health impact of stress on women who were pregnant during, or immediately after, a major earthquake and were living in the disaster area. Inherent resistance against the stress induced by the earthquake was also assessed.

Reactive nitrogen species formation in eosinophils and imbalance in nitric oxide metabolism are involved in atopic dermatitis-like skin lesions in NC/Nga mice.

Nitric oxide (NO) and reactive nitrogen species (RNS) have been implicated in the pathogenesis of inflammatory diseases. However, the involvement of NO and RNS in atopic dermatitis (AD), a pruritic inflammatory skin diseases, is not fully understood. In this study, we investigated the contribution of NO and RNS to the development of AD-like skin lesions in NC/Nga mice, an animal model for human AD. AD-like skin lesions were observed in NC/Nga mice kept under conventional conditions but not in specific pathogen-free conditions. The expression of inducible NO synthase (iNOS) and endothelial NOS (eNOS) proteins was upregulated in the dermal lesions, and that of neuronal NOS (nNOS) was downregulated in the epidermal lesions of the skin. Although the concentrations of and were lower, protein-bound nitrotyrosine content was significantly increased in the skin lesions. Immunohistochemical localization of nitrotyrosine was observed in almost all eosinophils. These results suggest that RNS formation in eosinophils and imbalance of NO metabolism are involved in the pathogenesis of AD-like skin lesions in NC/Nga mice.

Useful 1O2 (1Δg) generator, 3-(4′-methyl-1′-naphthyl)-propionic acid, 1′,4′-endoperoxide (NEPO), for dioxygenation of squalene (a skin surface lipid) in an organic solvent and bacterial killing in aqueous medium

3‐(4′‐Methyl‐1′‐naphthyl)‐propionic acid, 1′,4′‐endoperoxide (NEPO) provides singlet state of oxygen (1O2, 1Δg) at 37°C in sodium phosphate buffer (pH 7.2), acetate buffer (pH 4.5), methanol or chloroform, through the retro‐Diels‐Alder reaction. The total amount of 1O2 generated by NEPO was calculated using the following equation: [1O2]=[NEPO]0[1−exp−kt], where [1O2], [NEPO]0 and k are the total amount of 1O2 produced during the time t, initial concentration of NEPO and the first‐order reaction rate constant, respectively. When squalene was exposed to 1O2 which was generated thermolytically from NEPO, it was oxidized to three hydroperoxides, mono‐, di‐ and tri‐hydroperoxides, in amounts proportional to the dose of NEPO. The oxidizability of squalene was much more extensive compared with unsaturated phospholipids. Additionally, when wild‐type E. coli and lycopene‐producing mutant E. coli were exposed to NEPO‐derived 1O2, there was significant loss of viability of wild‐type E. coli but no significant loss of viability in lycopene‐producing strain, suggesting that lycopene by scavenging 1O2 protected E. coli against 1O2 toxicity.

Enhancement of a Sense of Coherence and Natural Killer Cell Activity which Occurred in Subjects who Improved their Exercise Habits through Health Education in the Workplace

Enhancement of a Sense of Coherence and Natural Killer Cell Activity which Occurred in Subjects who Improved their Exercise Habits through Health Education in the Workplace: Hiroyuki Nakamura, et al. Department of Environmental and Preventive Medicine, Graduate School of Medical Science, Kanazawa University— We have previously demonstrated that a sense of coherence (SOC), a candidate for a mediating stress factor, is involved in natural killer cell activity (NKCA) reduced in smokers, whereas the relationship among exercise, NKCA and SOC is unclear. To clarify the effects of exercise on SOC and NKCA, we examined the changes in SOC and NKCA before and after health education to encourage exercise. Of one‐hundred and one male office workers who received the health education for one year, 27 improved, 65 were unchanged and 9 had deteriorated exercise habits. The repeated measures analysis of variance showed that SOC in workers with improvement in the exercise habit were increased more significantly by the health education than those in workers without improvement (p<0.05). Although the change in NKCA produced by health education was recognized to be significantly different in those who had never smoked from that in current smokers (p<0.05), multiple regression analysis demonstrated that improvement in health practice significantly contributed to increases in both SOC (p<0.01) and NKCA (p<0.05) in never smokers, independently of other psychological factors. These results suggest that subjects with improvement in exercise enhance NKCA through increased SOC in never smokers.

1,2-DIACYLGLYCEROL HYDROPEROXIDES INDUCE THE GENERATION AND RELEASE OF SUPEROXIDE ANION FROM HUMAN POLYMORPHONUCLEAR LEUKOCYTES

We examined the effect of 1‐palmitoyl‐2‐linoleoylglycerol (PLG), PLG hydroxide (PLG‐OH), and PLG hydroperoxide (PLG‐OOH) on the release of superoxide anion from human PMNs monitored by the chemiluminescence generated by the superoxide anion‐sensitive reagent, 2‐methyl‐6‐(p‐methoxyphenyl)‐3,7‐dihydroimidazo[1,2‐a]pyrazin‐3‐one (MCLA). PLG‐OOH at low micromolar concentrations stimulated human PMNs whereas PLG and PLG‐OH did not. 1,3‐Dilinoleoylglycerol hydroperoxide, 1‐palmitoyl‐2‐linoleoylphosphatidylcholine hydroperoxide, and linoleic acid hydroperoxide were much less efficient in stimulating human PMNs than PLG‐OOH. The PKC inhibitors, chelerythrine chloride and staurosporine, inhibited the stimulation of PMNs. Possible pathophysiological role of 1,2‐diacylglycerol hydroperoxides is discussed.

Exploring Factors Associated With the Incidence of Sexual Harassment of Hospital Nurses by Patients

PURPOSE To identify factors affecting nurse-perceived sexual harassment and specific types of patient sexual behavior experienced by Japanese nurses. DESIGN Cross-sectional questionnaire study of Japanese hospital nurses. METHODS Self-administered questionnaires (N=600) were distributed to Japanese hospital nurses, and 464 were returned (response rate of 77.3%). Two instruments were used: one was for determining sexual harassment by patients, and the other was for determining specific types of patient behavior that had sexual connotations. FINDINGS Registered nurses were at a much higher risk of sexual harassment than were nurse assistants. In addition, registered nurses had a much more positive attitude toward gender equality compared with assistant nurses. CONCLUSIONS A positive attitude toward gender equality mediated by a relatively high education level might be associated with increasing reports of sexual harassment. An increasing incidence of sexual harassment claims among nurses should prompt hospital organizations to take proper action against it. Education on gender equality was thus considered a long-term solution for reducing the sexual harassment of Japanese hospital nurses. CLINICAL RELEVANCE Establishing a safer working environment could enable nurses to provide better care for patients and thereby promote the development of good relationships between nurses and patients.

Association between altered systemic inflammatory interleukin‐1β and natural killer cell activity and subsequently agitation in patients with alzheimer disease

Alzheimers disease (AD) is a neurodegenerative disorder that is the most common cause of dementia in the elderly and is frequently accompanied by emotional disorder, including agitation. Although evidence of neuroendocrine immune and inflammatory functions during emotional changes has been accumulated, the pathogenic mechanisms in the development of agitation accompanied by AD remain to be elucidated.