Objective. This study aimed to determine whether mental stress influences the plasma total homocysteine level or blood pressure in young men. Method. Twenty-seven male university students were assigned to a normal blood pressure group (24-h systolic blood pressure <125 mmHg and diastolic blood pressure <75 mmHg; 13 subjects) or a high blood pressure group (24-h systolic blood pressure > or =125 mmHg, or 24-h diastolic blood pressure > or =75 mmHg; 14 subjects). Wearing an ambulatory blood pressure monitoring device, subjects rested for 30 minutes, underwent an arithmetic test for 15 minutes, and rested again for 15 minutes. Blood samples were taken before and after the test. Plasma total homocysteine levels were measured. Heart rate, blood pressure, and sympathovagal balance were determined during the test. Results. The mean total homocysteine level at rest in the high blood pressure group was slightly, but not significantly, higher than that in the normal blood pressure group. The resting total homocysteine level was significantly higher in subjects with parental history of hypertension than in those without (p < 0.01). Blood pressure, heart rate, and the plasma total homocysteine level were increased significantly by mental stress (p < 0.05). The change in total homocysteine correlated significantly with the changes in systolic blood pressure and sympathovagal balance (p < 0.05). Conclusion. Resting total homocysteine level was significantly higher in male students with a parental history of hypertension than in those without. It was shown that mental stress elevates heart rate, blood pressure, sympathovagal activity, and the plasma total homocysteine level in young men.

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Variation in 24-h blood pressure (BP) is associated with multiple factors, but the association has not been thoroughly examined in young adults. To elucidate the potential factors associated with variation in 24-h BP, 331 healthy medical students were investigated. Awake mean BP negatively correlated with sleep duration in males. Sixty-seven subjects (20.2%) had a high 24-h BP according to the ESH/ESC 2007 guidelines (systolic blood pressure (SBP) 125 and/or diastolic blood pressure (DBP) 80 mmHg). After multivariate analysis for confounding factors, male gender, body mass index (BMI), smoking, the 24-h low/high frequency component (heart rate variability spectral analysis), and short sleep (5 h or less) were found to be associated with high BP. The present study is the first to demonstrate the multivariate risk factors for elevated 24-h BP in a large number of young adults. Further investigation is required to determine the causal relationship between modifiable BP-related factors and elevated 24-h BP in young adults.

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In 46 patients treated with PNL in our hospital, the intervals from PNL to removal of a catheter indwelled in the nephrostomy were studied. The intervals were longer in the cases with ureteral stones than those with renal stones probably because of the different degrees of obstruction. To investigate the degree and the interval of upper urinary tract obstruction after PNL, Pressure-flow Studies were performed every or every other day after PNL in 5 cases with renal stones and 5 cases with ureteral stones, selected from 46 cases. In Pressure-flow Studies, intrapelvic pressures were measured while saline mixed with pigment was being dripping at a rate of 5 ml/min into the renal pelvis through the nephrostomy catheter. Saline initially reached into the urinary bladder at an average of 4.8 days after PNL (range 3 to 7 days) with a mean intrapelvic pressure of 37.6 cmH2O (range 28 to 52 cmH2O) in the cases with renal stones and at an average of 9.2 days (range 7 to 12 days) with a mean intrapelvic pressure of 27.0 cmH2O (range 9 to 43 cmH2O) in the cases with ureteral stones. Pressure-flow Studies were performed again a few days after the initial passage of saline into the urinary bladder in 2 of 10 cases. The intrapelvic pressures, 16 cmH2O and 13 cmH2O, respectively, several days after the initial passage of saline were lower than those, 35 cmH2O and 43 cmH2O, respectively, at the initial passage of saline. Therefore, it was likely that the proper interval of indwelling catheter after PNL was about 7 to 8 days, in the cases with renal stones and about 11 to 12 days in the cases with ureteral stones.

We performed percutaneous nephrolithotomy (PNL) on 49 patients between May, 1986 and March, 1987. To investigate acute renal damage from PNL, we measured urinary NAG (N-acetyl-beta-D-glucosaminidase) and gamma-GTP (gamma-glutamyl transpeptidase) activities before PNL and for 6 days after PNL in 24 patients. The NAG activities elevated beyond normal level in 23 patients and gamma-GTP activities in 15 patients. NAG activities showed a peak level in the third day after PNL and gamma-GTP activities in the next day of PNL. After the peak both enzyme activities got down gradually. There was no difference in NAG and gamma-GTP activities between nephrostomy and lithotripsy in 2 staged patients. And the intrapelvic pressure during operation was at the normal level in 5 patients. Therefore, we think that the cause of NAG and gamma-GTP activity elevation is a mechanical damage, not an influence of the irrigation fluid. Large stones, long operation time and 2 stage procedure were the factors that produced high enzyme activities, because, we guess, the frequency of mechanical damages to the kidney increase in such cases. Postoperative pyrexia caused a slight increase in enzyme activities but preoperative hydronephrosis exerted no influence on both enzyme activities. We also measured creatinine clearance before and after PNL but no significant change was obtained. PNL causes only slight mechanical damage to the operated kidney which is reversible when assessed by NAG and gamma-GTP activities and the glomerular function is not affected. Therefore, we conclude that PNL is a safe treatment for upper urinary tract stones.