Yoko Ishihara

Differential genotoxicity of chemical properties and particle size of rare metal and metal oxide nanoparticles

Nanoparticles of rare metal compounds are used in various products. However, their carcinogenicity and genotoxicity have not been sufficiently evaluated. The tumor‐initiating and ‐promoting potentials of four rare metals, indium oxide (In2O3), dysprosium oxide (Dy2O3), tungsten oxide (WO3) and molybdenum (Mo), with a well‐defined particle diameter were evaluated. The mutagenicity of these rare metals was investigated by Ames test using five bacteria strains, and transformability of these rare metals was investigated by cell‐transformation assay using v‐Ha‐ras‐transfected BALB/c 3T3 cells (Bhas 42 cells). Nano‐sized Dy2O3 showed strong mutagenesis in all five bacteria strains tested with and without metabolic activation, while micro‐sized particles showed weak mutagenesis in two bacterial strains. Dy2O3 induced transformation colonies of Bhas 42 cell dose‐dependently, although there was no difference in the number of transformed foci between nano‐sized and micro‐sized particles. Nano‐sized In2O3 and WO3 showed positive mutagenic response in TA1537 and TA98, respectively, whereas the micro‐sized metal oxide particles showed no mutagenesis in the test bacterial strains. Both nano‐sized and micro‐sized In2O3 showed similar levels of transformability. However, nano‐sized and micro‐sized WO3 did not show any transformability. Both nano‐sized and micro‐sized Mo particles showed neither mutagenesis nor transformability. These results suggest that mutagenicity of rare metals depends on their particle size, although transformability depends on their chemical components but not on their particle size. Copyright

Contribution of cytokines on the suppression of lung metastasis

Weekly injection of a protein-bound polysaccharide PSK in mice with Lewis Lung Cancer (LLC) significantly decreased the number of lung metastatic foci concomitant with enhancement of cytostatic activity in the bronchoalveolar lavage (BAL) cells. These effects were more marked when the agent was given intratracheally, inducing a larger number of pulmonary macrophages, lymphocytes and neutrophils concomitant with increases in BAL tumor necrosis factor-α (TNF-α), mouse inflammatory protein-α (MIP-1α), mouse inflammatory protein-β (MIP-1β), interleukin-1α (IL-1α) and interleukin-6 (IL-6), but not interleukin-2(IL-2) and interleukin-4 (IL-4). Pre-treatment with anti TNF-α antibody reduced these effects. The time course and production of PSK-induced cytokines were similar between the tumor-bearing mice and control mice. BAL neutrophils in mice with LLC showed a tendency toward acceleration of O2- production compared with circulating neutrophils. Pulmonary macrophage phagocytosis was also significantly higher in the LLC mice.These results suggest that enhancement of cytostasis appears to be induced by activation and/or improvement of function in inflammatory and immune cells through cytokines under immunomodulator treatment in lung metastasis, possibly via a TNF-α-dependent mechanism.

Absorption and Tissue Distribution of an Immunomodulatory α-D-Glucan after Oral Administration of Tricholoma matsutake

Alpha-D-glucan (MPG-1) separated from Tricholoma matsutake (CM6271) has been reported to show immunomodulatory activities. In this study, the plasma concentration and tissue distribution of MPG-1 after CM6271 oral administration were investigated as part of the action mechanism analysis. When CM6271 was orally administered in a single dose to mice, MPG-1 was absorbed via the intestinal tract, appeared in plasma after 16 h, was gradually excreted from the blood, and fell to background level after 48 h. The time course analysis of MPG-1 in plasma showed the following pharmacokinetic parameters of MPG-1: tmax = 24 h; Cmax = 161.1 ng/mL; AUC(0-infinity) = 2559.7 ng x h/mL. Moreover, MPG-1 was confirmed to localize in Peyers patches, mesenteric lymph nodes (MLN), and the spleen and to promote IL-12 p70 production and NK cell activity. These results suggest that MPG-1 stimulated the intestinal immune system through Peyers patches; moreover, it was taken into the blood and stimulated the systemic immune system.

Chronic diesel exhaust exposures of rats demonstrate concentration and time-dependent effects on pulmonary inflammation

Long-term, repeated exposure to particles in air pollution increases the risk for chronic respiratory diseases and cardiorespiratory mortality. The biological linkages remain poorly understood in chronic exposure to particle matter. To elucidate and verify these linkages, we investigated long-term exposure to diesel emission with respect to dose dependence and the effect of components without particles from diesel emission in rats. Wistar rats were exposed to filtered air (C group), diesel exhaust at low (L group), medium (M group), and high level (H group), or at a medium concentration diesel exhaust without particulate matter (MG group), for 16 h/day, 6 days/wk, for 6, 12, 18, or 24 mo. Anesthetized animals were sacrificed and bronchoalveolar lavage (BAL) fluid from the lung and blood from the right ventricle were collected. Various biomarkers of inflammation and components of mucus and surfactant were determined. Changes in total cell counts and cell differentiation, total protein, mucus and surfactant components, and prostaglandin E 2 in BAL fluid, but not biomarkers in plasma, showed statistical differences among the C, L, M, and H groups during the experimental period. The changes in these biomarkers in the H group were greater than those in the M group, whereas those in the L group showed no significant changes compared with those in the C group during the experimental period. The onset of significant changes in inflammatory cells and these biomarkers in BAL fluid for the M and H groups was at 6 to 12 mo of exposure. The maximum level was reached at 12 to 18 mo of exposure. Although BAL prostaglandin E 2 decreased significantly at 6 mo of exposure in the M and H groups, this trend was not observed in the C and L groups. Animals exposed to a medium level of diesel exhaust without particulate matter showed significantly less inflammatory cells and various biomarkers in BAL fluid than animals exposed to the same level of diesel exhaust with particulate matter during the experimental period. These findings suggest that biological response to inhaled particles is aggravated during chronic exposure to diesel exhaust dose-dependently. Inflammation and overproduction of mucus and surfactant components reached a plateau at 12 or 18 mo of exposure during a 24-mo experimental period. No adverse effect of particles (less than 1.0 mg particles/m 3 of diesel emission) was observed in these rats. However, our data suggest that particulate matter plays an important role during development of chronic lung injury induced by diesel emission exhaust.

Effects of acute and chronic cigarette smoking on the expression of endothelin-1 mRNA of the cardiovascular tissues in rats.

Although smoking has been suggested to be involved in the development of cardiovascular diseases, details of the mechanism still need to be revealed. We investigated the effects of cigarette smoking on the tissue mRNA expression of endothelin-1 (ET-1). Male Wistar rats of 4 weeks of age were exposed to smoke from six cigarettes for 30 min (acute exposure) and six cigarettes for 30 min/day, 5 days a week for 6 months (chronic exposure). Half of the rats exposed to 6 months smoking were kept in clean-air conditions for a further 3 months to clear the effects. Tissue expression of ET-1 mRNA in the kidney, aorta, heart and lung was determined by reverse transcriptase polymerase chain reaction (RT-PCR) followed by Southern blot analysis. There was no significant difference in body and organ weight of the heart and kidney between the control and smoking group in either the acute or chronic experiment. In the acute-exposure experiment, expression of ET-1 mRNA was increased in the heart and lung, while that in the kidney and aorta was unchanged. In the chronic-exposure experiment, however, there was no significant difference in the expression of ET-1 mRNA in all the tissues between the smoking and control groups. These results suggest that cigarette smoking could cause cardiovascular and pulmonary diseases by modulating ET-1 mRNA expression in the tissues.

Inhibition of Decrease in Natural Killer Cell Activity in Repeatedly Restraint-Stressed Mice by a Biological Response Modifier Derived from Cultured Mycelia of the Basidiomycete Tricholoma matsutake

Objective: To develop a method to cope with stress-induced reduction in immunocompetence, we evaluated the immunomodulatory activities of a biological response modifier derived from the mycelia of the basidiomycete Tricholoma matsutake (CM6271) in mice under repeated restraint stress. Methods: C57BL/6 mice were inserted, one per tube, into 50-ml polypropylene tubes into which more than 30 ventilation holes had been drilled, and were restrained everyday for 20 days in this fashion for set periods of time. Natural killer (NK) cell activity and NK1.1-positive cell counts in the spleen, ACTH and corticosterone levels in the blood were determined. CM6271 was orally administered daily during the restraint stress period. Results: (1) When the mice were restrained in a confined space for 6 h per day for 20 days, the NK cell activity and the NK1.1-positive cell counts in the spleen significantly decreased after day 5 with an increase in the blood ACTH and corticosterone levels. (2) Oral administration of CM6271 during the restraint stress period significantly prevented the stress-induced decrease in NK cell activity. The effect was dependent on the timing, duration, and doses administered. (3) CM6271 did not significantly affect the splenic NK1.1-positive cell counts or the levels of blood ACTH and corticosterone in restraint-stressed mice. Conclusion: The above findings suggest that CM6271 inhibits the restraint stress-induced decrease of NK cell activity in a timing of administration and dose-dependent manner.

Expression and mutation of p53 gene in the lung of mice intratracheal injected with crystalline silica

The genotoxic effect of crystalline silica (Qt) in the lung was studied to clarify that silicosis conferred a significant increase in risk subsequent lung cancer. C57BL/6N mice received a single tracheal injection of Qt at dose of 2 mg/mouse. Lung p53mRNA was suppressed significantly, but no change of p21mRNA 15 months after treatment. Mutation of p53 gene was not identified at 15 months in the Qt group. Silicotic lesions were observed in the lungs of Qt group, but silicosis with pulmonary neoplasia was no detected. These results indicated that genetic changes in the silicotic lung might lead to facilitation of carcinogenesis.

Effects of gender, age, family support, and treatment on perceived stress and coping of patients with type 2 diabetes mellitus

BackgroundWe previously found that the empowerment of patients with type 2 diabetes mellitus can be strongly affected by gender and age in addition to self-managed diet and exercise behaviors and treatment. This study was to examine the effects of gender, age, family support, and treatment on the perceived stress and coping of patients with type 2 diabetes mellitus living with family.MethodsA survey was conducted of 140 adults with type 2 diabetes mellitus who were living with family. There was no significant difference in hemoglobin A1c (HbA1c) between male and female. Perceived stress and coping were measured with the Japanese version of the Appraisal of Diabetes Scale and the Lazarus Type Stress Coping Inventory. Stepwise regression analysis and path analysis were performed to identify factors that affect the perceived stress and coping of patients.Results(1) Perceived stress and coping were strongly affected by gender. (2) Perceived stress and coping were affected by age for males, but perceived stress was not affected by age for females. However, females showed a greater “psychological impact of diabetes” than did males. Females aged between 50 and 69 years engaged in active problem solving, but awareness of diabetes was low. (3) Treatment regimens had an effect on HbA1c for both sexes, and diet therapy affected the awareness of diabetes of males and coping of females. (4) For females, “sense of self-control” was strongly associated with coping, and those who were living with non-spouse family members had a greater psychological impact of diabetes than those living with only their spouse. (5) For males, coping was strongly affected by living with their spouse.ConclusionsThe results suggest that perceived stress, coping, and diet regimen are deeply associated with gender and age and that a male with type 2 diabetes mellitus living with his spouse is strongly dependent on support from the spouse. It is important to take into account gender, age, and family environment to provide patients with an individualized approach to addressing perceived stress and to provide education program for coping that can maximize treatment and maintain better, continuous glycemic control.

The reliability and validity of the Japanese version of the Appraisal of Diabetes Scale for type 2 diabetes patients

AIMSnAn appropriate questionnaire for measurement of the psychological burden of self-management or behavior modification in type-2 diabetes patients has yet to be developed in Japan. This study was conducted to test the reliability and validity of the Japanese version of the Appraisal of Diabetes Scale (ADS).nnnMETHODSnthe study enrolled 346 Japanese patients with type 2 diabetes: 200 men and 146 women who were 63.2 ± 10.1 and 62.2 ± 11.9 years of age and had HbA1c levels of 6.9 ± 1.2% and 7.3 ± 1.9%, respectively.nnnRESULTSnthe questionnaire was divided into three components: Psychological impact of diabetes, Sense of self-control, and Efforts for symptom management. Cronbachs alpha was 0.746-0.628. Significant correlations were observed between Sense of self-control and self-managed dietary and exercise behaviors and HbA1c levels; between Psychological impact of diabetes and various treatments, symptoms causing anxiety, and HbA1c levels; and between Efforts for symptom management and dietary and nutritional behaviors. The questionnaire showed better evidence of internal consistency, test-retest reliability and validity.nnnCONCLUSIONnour results suggested that the Japanese version of ADS may be a useful tool for the quick assessment of common anxieties and motivation toward treatment in patients with type 2 diabetes.

Expression of matrix metalloproteinase, tissue inhibitors of metalloproteinase and adhesion molecules in silicotic mice with lung tumor metastasis

The number of metastatic foci in silicotic mice is approximately 1.5-fold that in normal mice and in mice treated with TiO2 as inert particles. Expression of matrix metalloproteinases (MMPs) tissue inhibitors of metalloproteinases (TIMPs) and selectins was investigated in silicotic mice with lung tumor metastasis. Expression of MMP-9 and P-selectin mRNA, but not MMP-2 and E-selectin, increased significantly, showing decreases of the ratio of expression in TIMPs/MMP-9 in tumor-bearing silicotic mice compared with the tumor-bearing normal mice and mice treated with TiO2. Pretreatment with anti-P-selectin antibody inhibited number of metastatic foci significantly in silicotic mice, while pretreatment of animals with anti MMP-9 antibody showed slight decrease of metastatic foci. This evidence indicated that up-regulation of P-selectin expression contributed to enhanced rate of tumor metastasis in lung with silicosis.