Satomi Shibazaki

Interindividual variation in cytogenetic response to X-ray and colchicine measured with the cytokinesis-block micronucleus assay.

Interindividual variation in cytogenetic response to two different types of micronucleus (MN) inducer, X-rays (a clastogen) and colchicine (a spindle poison), was investigated in the peripheral blood lymphocytes of normal healthy donors by the cytokinesis-block MN method. The data for 124 donors between the ages of 19 and 80 years showed that the histogram of individual frequency of X-ray (2 Gy)-induced micronucleated cells followed the normal distribution (Shapiro Wilks W-test) with a significant interindividual variance (ANOVA, p < 0.001). This was, however, not the case for colchicine (0.03 microgram/ml)-induced micronucleated cells. Instead, a skewed distribution illustrating interindividual variation was evident (ANOVA, p < 0.001). Statistical analysis of the effect of age and sex on MN incidence by using the Kruskal-Wallis test indicated that age affected the baseline and colchicine-induced MN incidences strongly but not the X-ray-induced MN incidence. There was no effect of sex on the incidence of micronuclei induced by either agent. In order to avoid any possible effect of age on the MN index, data for young subjects aged less than 30 years old were analyzed separately. The results of this analysis again showed significant interindividual variations in baseline, X-ray-induced, and colchicine-induced micronucleated cell rates. Results of the correlation-coefficient analysis showed that neither X-ray-induced MN incidence nor colchicine-induced MN incidence was related to baseline MN incidence. No correlation between X-ray-induced and colchicine-induced MN incidences was also found by this analysis. These results suggest that interindividual variance in chromosomal response to mutagens in normal populations may be a real phenomenon, as is interindividual variance in baseline MN frequency, and that individual susceptibilities to the two different types of micronucleus inducers (X-ray and colchicine) are unrelated, and the baseline MN level is not of predictive value for the susceptibilities.

Lifestyle Modifications Versus Antihypertensive Medications in Reducing Cardiovascular Events in an Aging Society: A Success Rate-oriented Simulation

Objective It is difficult to compare directly the practical effects of lifestyle modifications and antihypertensive medications on reducing cardiovascular disease (CVD). The purpose of this study was to compare the hypothetical potential of lifestyle modifications with that of antihypertensive medications in reducing CVD in an aging society using a success rate-oriented simulation. Methods We constructed a simulation model for virtual Japanese subpopulations according to sex and age at 10-year intervals from 40 years of age as an example of an aging society. The fractional incidence rate of CVD was calculated as the product of the incidence rate at each systolic blood pressure (SBP) level and the proportion of the SBP frequency distribution in the fractional subpopulations of each SBP. The total incidence rate was calculated by the definite integral of the fractional incidence rate at each SBP level in the sex- and age-specific subpopulations. Results If we consider the effects of lifestyle modifications on metabolic factors and transfer them onto SBP, the reductions in the total incidence rate of CVD were competitive between lifestyle modifications and antihypertensive medications in realistic scenarios. In middle-aged women, the preventive effects of both approaches were limited due to a low incidence rate. In middle-aged men and extremely elderly subjects whose adherence to antihypertensive medications is predicted to be low, lifestyle modifications could be an alternative choice. Conclusion The success rate-oriented simulation suggests that the effectiveness of lifestyle modifications or antihypertensive medications in preventing cardiovascular events largely depends on the baseline incidence rate and sex- and age-specific behavioral factors.

Lifestyle modifications supported by regional health nurses lowered insulin resistance, oxidative stress and central blood pressure in subjects with metabolic syndrome

BACKGROUND This study was attempted to investigate whether lifestyle modifications supported by regional health nurses should improve cardio-metabolic factors--including adipocytokines, oxidative stress, and arterial stiffness--in subjects with metabolic syndrome. METHODS Thirty-six subjects with metabolic syndrome were enrolled, 28 of whom completed the 6-month lifestyle modifications (male:female=19:9). Blood and urine test results were examined in relation to metabolic factors before and after 6-month nutritional and physical activity modifications. In addition, oral glucose tolerance tests were performed and arterial stiffness was measured by brachial-ankle pulse wave velocity and radial augmentation index before and after them. RESULTS Six-month lifestyle modifications significantly reduced body weight, homeostasis model assessment index, and low-density lipoprotein cholesterol (LDL-C). They significantly attenuated oxidative stress measured by the urinary 8-hydroxy-2-deoxyguanosine/creatinine ratio. They also lowered brachial and central systolic blood pressure. They tended to decrease waist circumferences and the levels of C-reactive protein. However they did not significantly change the levels of adipocytokines, including tumour necrosis factor, soluble tumour necrosis factor receptors, and interleukin 6, or arterial stiffness measured by brachial-ankle pulse wave velocity and radial augmentation index. CONCLUSIONS Six-month lifestyle modifications supported by regional health nurses lowered body weight, insulin resistance, LDL-C, oxidative stress, and peripheral and central blood pressure in subjects with metabolic syndrome.

Antihypertensive medication versus health promotion for improving metabolic syndrome in preventing cardiovascular events: a success rate-oriented simulation study

BackgroundIn practice, it is difficult to compare the effectiveness of traditional antihypertensive treatment with that of health promotion in reducing incidence rate of cardiovascular disease (IRCVD, events/year). This simulation study compared the effectiveness of two approaches to reducing IRCVD in a sample population: a traditional approach, in which high-risk patients are treated with conventional antihypertensive medications, and a population-based approach, in which subjects participate in a health promotion program.MethodsWe constructed a simulation model for a sample population of middle-aged Japanese men whose systolic blood pressure (SBP) levels are normally distributed (130 ± 20 mm Hg). The principal assumption was that IRCVD increases exponentially according to SBP. The population IRCVD was calculated as the product of the distribution of SBP multiplied by IRCVD at each SBP. The cumulative IRCVD was calculated by the definite integral from the lowest to the highest SBP of IRCVD at each SBP level. The success rates were calculated according to SBP and metabolic risk profiles in the two approaches, respectively.ResultsThe reduction in IRCVD was twice as large for antihypertensive medications as it was for health promotion in several situations. For example, if adherence to antihypertensive treatment occurred at a realistic level, the decrease in IRCVD was estimated at 9.99 × 10-4. In contrast, even if the health program was promoted optimistically, the decrease in IRCVD was estimated at 4.69 × 10-4.ConclusionsThe success rate-oriented simulation suggests that prescribing antihypertensive medications is superior to promoting the health promotion program in reducing IRCVD in virtual middle-aged Japanese men.