Isao Sato

Phosphorus-31 magnetic resonance spectroscopy of forearm flexor muscles in student rowers using an exercise protocol adjusted for differences in cross-sectional muscle area

SummaryTo assess exercise energy metabolism of forearm flexor muscles in rowers, six male student rowers and six control subjects matched for age and sex were studied using phosphorus-31 magnetic resonance spectroscopy (31P-MRS). Firstly, to adjust for the effect of differences in cross-sectional muscle area, the maximal cross-sectional area (CSAmax) of the forearm flexor muscles was estimated in each individual using magnetic resonance imaging. Multistage exercise was then carried out with an initial energy production of 1 J · cm−2 CSAmax for 1 min and an increment of 1 J · cm−2 CSAmax every minute to the point of muscle exhaustion. A series of measurements of31P-MRS were performed every minute. The CSAmax was significantly greater in the student rowers than in the control subjects [19.8 (SD 2.2) vs 17.1 (SD 1.2) cm2,P<0.05]. The absolute maximal exercise intensity (J · min−1) was greater in the rowers than in the control subjects. However, the maximal exercise intensity per unit of muscle cross sectional area (J · min−1 · cm−2) was not significantly different between the two groups. During mild to moderate exercise intensities, a decrease in phosphocreatine and an increase in inorganic phosphate before the onset of acidosis were significantly less in the rowers, indicating a requirement of less adenosine 5′-diphosphate to drive adenosine 5′-triphosphate production. The onset of acidosis was also significantly delayed in the rowers. No difference was observed in forearm blood flow between the two groups at the same exercise intensity (J · min−1 · cm−2). These results demonstrated that the findings of the maintenance of a higher level of phosphocreatine and a lower level of inorganic phosphate with less acidosis observed in the rowers were the results of the intrinsic characteristics of energy metabolism of their muscles and that these characteristics were independent of their greater cross-sectional muscle area.

Relationship between lipids and angiographically defined coronary artery disease in Japanese patients

The relationship between the severity and extent of coronary artery disease (CAD) and the lipid profiles was evaluated in 120 Japanese male patients, who underwent coronary angiography. Analysis of the lipid quartile distribution showed that the percentage of patients with significant CAD increased as the total cholesterol (TC) increased and high-density lipoprotein cholesterol (HDL-C) decreased. In addition, as the number of vessels with marked coronary artery stenosis increased, TC and TC/HDL-C increased while HDL-C decreased. However, within this population, triglyceride level, high blood pressure, and smoking were not significantly associated with coronary angiographic findings.

The incidence of cardiac events in Japanese men with atypical or nonanginal chest pain: a prospective study on the significance of exercise testing.

The incidence of cardiac events in Japanese men (mean age 54 +/- 10 years) with atypical or nonanginal chest pain was assessed prospectively. Three groups of patients, those with typical angina (TA; n = 134), those with atypical angina (AA; n = 192), and those with nonanginal chest pain (NA; n = 311) were studied with regard to cardiac events (cardiac death or nonfatal myocardial infarction), risk factors, and results of exercise testing. The total cholesterol and high-density lipoprotein-cholesterol levels were significantly different among the three groups, but no differences were observed for other risk factors. The incidences of cardiac events were 8.5%, 2.2%, and 1.3% in the TA, AA, and NA groups, respectively (p less than 0.05) during 3.2 +/- 1.5 years. Significant ST segment changes were observed in 70.1%, 25.5%, and 18.0% of the patients in the TA, AA, and NA groups, respectively, at the time of enrollment. The risk ratio for cardiac events in a positive exercise test was 1.7 (difference not significant) for the TA group and 6.1 (p less than 0.05) for the others combined (AA and NA groups). The risk ratio adjusted for risk factors (Cox model) was 2.2 (difference not significant) for the TA group and 4.9 (p less than 0.05) for the AA and NA groups combined. In conclusion, the incidence of cardiac events in those with AA or NA chest pain was relatively low in Japan, but the independent prognostic significance of positive exercise testing was demonstrated in this group of patients.