Takemasa Watanabe

Gender difference in age-related changes in muscle sympathetic nerve activity in healthy subjects

Muscle sympathetic nerve activity (MSNA) was measured directly along with blood pressure at rest in 69 healthy women (20-79 yr old) and 76 age-matched healthy men (16-80 yr old). All were nonobese and normotensive. In the women and men the MSNA was positively correlated with age (women: y = 0.788 x - 5.418, r = 0.846, P < 0.0001; men: y = 0.452 x + 12.565, r = 0.751, P < 0.0001). The regression intercept of y was significantly lower ( P < 0.0001) in the women than in the men, and the regression slope was significantly steeper ( P < 0.0001) in the women. The MSNA was lower in women than in men among those <30 ( P = 0.0012), 30-39 ( P = 0.0126), and 40-49 yr old ( P = 0.0462) but was similar in women and men among those 50-59 ( P = 0.1911, NS) and ≥60 yr old ( P = 0.1739, NS). The results suggest that MSNA increases with age in women and men and that the activity is markedly lower in young women than in men but is markedly accelerated with age.

Baroreflex control of muscle sympathetic nerve activity is attenuated in the elderly.

To determine whether the baroreflex control of sympathetic nerve activity is attenuated in the elderly, muscle sympathetic nerve activity (MSNA) from the tibial nerve was monitored using microneurography, and heart rate and blood pressure were recorded during the depressor (phase II) or pressor (phase IV) period to Valsalvas maneuver in 10 younger subjects and 7 aged subjects. The baroreflex slope for heart rate showed attenuation in the aged subjects during the pressor phase but not during the depressor phase, the baroreflex slope for MSNA was also attenuated in the aged subjects during the pressor and tended to be attenuated during the depressor phases. These data suggest impaired baroreflex function for both heart rate and sympathetic nerve activity in the elderly.

Effects of aerobic exercise conditioning at intensities corresponding to lactate threshold in the elderly

SummaryIn this study we attempted to determine the effects of exercise training at the intensity corresponding to lactate threshold (Thla−) on various health-related variables in sedentary but apparently healthy elderly subjects. Six men and five women volunteers [mean age 68.9 (SD 3.4) years] performed supervised endurance-type training on stationary cycle ergometers for 30 min and recreational activities for 30 min, 3 days a week for 12 weeks. Four men and four women served as the control group [68.8 (SD 4.4) years]. As a result of the training programme, statistically significant increases in maximal oxygen consumption (10%), oxygen consumption at Thla−(18%), distance covered in 12-min walk, side step, and leg extensor power were found in the training group, while no changes occurred in the control group. The changes in serum cholesterol and triglyceride concentrations from the pre- to post-training period were statistically significant. High-density lipoprotein cholesterol remained unchanged, and low-density lipoprotein cholesterol tended to decrease following the training programme. These data would indicate that exercise training at the intensity corresponding to Thla−may have favourable effects on overall physical fitness and some serum lipid variables in older individuals.

Successful treatments of lung injury and skin burn due to hydrofluoric acid exposure

Abstract Recent growth in the electronics and chemical industries has brought about a progressive increase in the use of hydrofluoric acid (HF), along with the concomitant risk of acute poisoning among HF workers. We report severe cases of inhalation exposure and skin injury which were successfully treated by administering a 5% calcium gluconate solution with a nebulizer and applying 2.5% calcium gluconate jelly, respectively. Case 1: A 52-year old worker used HF for surface treatment after welding stainless steel, and was hospitalized with rapid onset of severe dyspnea. On admission to the critical care medical center he had widespread wheezing and crackles in his lungs. Chest radiograph showed a fine diffuse veiling over both lower pulmonary fields. Severe hypocalcemia with high concentrations of F in serum and urine were disclosed. He was immediately given 5% calcium gluconate solution by intermittent positive-pressure breathing (IPPB), utilizing a neblizer. On the 21st hospital day, chest film and CT scan did not demonstrate any abnormality. He was discharged very much improved on the 22nd hospital day. Case 2: A 35-year old worker at an electronics factory was admitted to his local hospital with severe skin burn on his face and neck after exposure to 100% HF. Treatment began with immediate copious washing with water for 20 min. Calcium gluconate 2.5% gel (HF burn jelly) was applied to the area as a first-aid measure. Persistent high concentrations of serum and urinary F were disclosed for 2 weeks. After treatment with applications of HF burn jelly, he was confirmed as being completely recovered. The present cases and a review of published data suggest that an adequate method of emergency treatment for accidental HF poisoning is necessary.

Effects of vital exhaustion on cardiac autonomic nervous functions assessed by heart rate variability at rest in middle-aged male workers

We investigated the effects of vital exhaustion (VE) on cardiac autonomic functions in relation to working conditions such as overtime and frequent business trips, and to lifestyles such as smoking on 52 healthy middle-aged male workers. VE was evaluated by an abbreviated Maastricht Vital Exhaustion Questionnaire. Cardiac autonomic function atsupine rest was assessed by spectral analysis of heart rate variability inanannual healthcheckup.Themeanamplitudeofthehigh frequency(HF: 0.15-0.4 Hz) component was lowerinthe high-VE group, whereas no significant difference in the ratio ofthe low frequency (LF: 0.04-0.15 Hz) component powerto HF power (the LF/HF ratio) was observed among VE groups. There were significant interactive effects of VE and smoking on HF amplitude, and of VE and frequent business trips on the LF/HF ratio. VE symptoms were related to the suppression of the cardiac parasympathetic nervous functionat rest in middle-aged male workers, but not to the alteration in sympathovagal balance. Smoking and overwork such as frequent business trips may amplify the autonomic dysfunction in relation to VE among workers with a pronounced feeling of VE.

Skin sympathetic activity in the tibial nerve triggered by vibration applied to the hand

SummaryThe effect of vibration applied to the hand on skin sympathetic activity (SSA) in the lower limbs was studied in five healthy subjects. SSA from the right tibial nerve at the popliteal fossa, plethysmogram from the right index toe and perspiration from the sole of the rigth foot were measured when vibration of 100m/s2 at 60 Hz was applied to the left palm for 1 min. The SSA response to vibration exposure differed among subjects, but every subject showed an increase in SSA from the tibial nerve when vibration was applied to the hand. Decrease in amplitude of plethysmogram from the toe was also found in all subjects. One subject displayed a remarkable increase in perspiration on the sole of the foot together with a great increase in SSA. The present findings indicated that even vibration exposure of the hand triggers sympathetic activity in the tibial nerve innervating the foot, and causes vasoconstriction of the toe and perspiration on the sole of the foot.

Blood Pressure and Heart Rate Variability in Taxi Drivers on Long Duty Schedules

Blood Pressure and Heart Rate Variability in Taxi Drivers on Long Duty Schedules: Fumio KObayashi, et al. Department of Health and Psychosocial Medicine, Aichi Medical University School of Medicine

Hemodialyzability of ionizable fluoride in hemodialysis session.

The fluoride ion content in serum and in dialysate medium was determined by means of a fluoride ion-selective electrode in 29 patients undergoing hemodialysis treatment. Abnormally high serum fluoride of 65.9 +/- 28.3 microg l(-1) at the beginning and 46.5 +/- 26.7 microg l(-1) at the completion of the hemodialysis session was observed. Results showed that 60.0 +/- 23.9% of the serum fluoride at the beginning of the session was theoretically filterable, and 80.8 +/- 42.4% of this fraction was actually filtered throughout the hemodialysis session. The dialysis procedure is considered to be safe and adequate for serum fluoride removal. The high serum fluoride at the completion of the hemodialysis session was thought to originate from the fraction of unfilterable binding fluoride. To make further progress towards improvements in serum fluoride removal during HD, attention to the binding fraction of serum fluoride is required.

Incidence of disability in housebound elderly people in a rural community in Japan

Background:  Although being housebound is acknowledged conceptually as a risk factor for disability and social isolation, there has been little epidemiologic research on housebound status. This study aimed to explore whether being housebound is a risk factor for disability and whether a low level of social contact increases that risk in elderly persons.

Assessment of Sympathetic Nerve Activity Controlling Blood Pressure in the Elderly Using Head-Up Tilt1

In order to assess age-related changes in sympathetic nerve activity controlling blood pressure, we recorded muscle sympathetic nerve activity, blood pressure, and heart rate during head-up tilt in 10 healthy elderly (69-75 years) and 16 healthy young (19-23 years) subjects. The elderly had significantly lower responsiveness of muscle sympathetic nerve activity to postural change than did the young subjects. In the elderly, marked rise in blood pressure without increase in muscle sympathetic nerve activity was observed in nearly upright position during head-up tilt, whereas this phenomenon was not observed in the young. We conclude that neural control function of blood pressure during head-up tilt in the elderly differs from that in the young, which may be due to age-related change in baroreflex function.