This study was conducted in healthy Japanese subjects to examine the effects of age and gender on the relationship between the risk factors for cardiovascular disease (CVD) and augmentation index (AI), and the effects of clusters of those risk factors on AI. Radial arterial pressure wave analysis was used to obtain AI in 3675 men and 2919 women. AI was found to be higher in women than in men, and age-related increase in AI showed an attenuated curve in subjects aged X50 years. A step-wise multivariate linear regression analysis showed that mean blood pressure and smoking are independent significant variables related to AI in men regardless of age, and in women aged o50 years, but not in women aged X50 years. A general linear model univariate linear regression analysis showed that mean blood pressure and smoking had a significant interaction for their relation with AI in men, but not in women. In conclusion, among the risk factors for CVD, smoking and blood pressure were found to be independent factors related to increase in AI. Although age-related attenuation of increase in AI was confirmed in Japanese subjects, these risk factors may act to increase AI even in elderly subjects, at least in part. However, the effects of these factors on AI may differ based on gender, and these factors may act synergistically to increase AI in men. On the contrary, these factors may act independently in young women to increase AI without interaction, whereas only the blood pressure seems to increase AI in elderly women. Keywords: age; augmentation index; gender; risk factors INTRODUCTION Accumulating evidence suggest that increased arterial stiffness is an independent risk for cardiovascular disease (CVD). 1-3 The augmentation index (AI) is a marker related to systemic arterial stiffness, and some studies reported that increased AI or central blood pressure estimated by AI predicts future cardiovascular events. [4][5][6] Some studies reported that CVD risk factors affect AI. 7-11 The age-related increase in AI shows an attenuated curve in subjects aged 450 years, and AI is thought to be less sensitive in reflecting arterial stiffness in elderly subjects. 12 Although AI increases predominantly in women, the Second Australian National Blood Pressure Study (ANBP 2 study) showed that it cannot be used as a marker for predicting future CVD events in elderly women with hypertension. 13 Matsui et al. 14 examined the effects of age and gender on AI in subjects with hypertension under anti-hypertensive medication. However, their study could not avoid the influence of anti-hypertensive medication on the results. Thus, the effects of both age and gender on the relationship between the risk factors for CVD and AI in healthy individuals have not been fully clarified. Furthermore, although it is noted that a cluster of those risk factors additively or synergistically augments the progression of

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SDBs, DDBs, and DBs can be differentiated by photoacoustic signals, suggesting that the method proposed is useful for diagnosing burn injuries.

We perform measurement of photoacoustic (PA) signals for burned skin in rats in the spectral range of 500 to 650 nm. The wavelength dependence of PA signal amplitude shows characteristics similar to those of the absorption spectrum of hemoglobin, suggesting that the PA signal originates from blood in the uninjured skin tissue under the injured tissue layer. High-contrast signals are obtained in the spectral range of 532 to 580 nm. At 550 nm, a PA detector is scanned on the wounds and PA tomograms are obtained. The tomograms clearly show the zones of stasis, demonstrating that a 2-D PA measurement is useful for burn depth assessment.