Search PubMed⌕ Search

Biomedical subjects

Jun Sugawara

Publications and source records attributed to Jun Sugawara.

17 recordsLinked to original sources
PubMed2007

Relationship between augmentation index obtained from carotid and radial artery pressure waveforms.

OBJECTIVE: Increased aortic and carotid arterial augmentation index (AI) has been directly linked with cardiovascular disease risk, mortality and morbidity. The aim of this study was to examine whether AI obtained directly from radial artery pressure waveforms (radial AI) can provide information comparable with carotid arterial AI measurements. METHODS: In a cross-sectional study of 204 apparently healthy subjects (88 men and 116 women) aged 19-76 years (51 +/- 15 years, mean +/- SD), carotid AI [(second peak carotid systolic pressure - first peak carotid systolic pressure)/carotid pulse pressure*100] and radial AI [(second peak radial systolic pressure - diastolic pressure)/(first peak radial systolic pressure - diastolic pressure)*100] were measured using applanation tonometry. RESULTS: Radial AI was strongly correlated with carotid AI (r = 0.86, P < 0.0001, SD of difference 10.0%), although radial AI was consistently approximately 66% higher than carotid AI. In 16 apparently healthy young adults (11 men and five women, aged 23 +/- 3 years) handgrip exercise was immediately followed by post-exercise muscle ischaemia (PEMI) to compare changes in carotid and radial AI during increased sympathetic nervous activity. PEMI caused parallel increases in carotid and radial AI (26 and 19%). Accordingly, changes in radial AI with PEMI were strongly correlated with corresponding changes in carotid AI (r = 0.86, P < 0.0001, SD of difference 7.3%). CONCLUSION: These results suggest that AI obtained directly from radial arterial pressure waveforms could provide equivalent information to carotid arterial AI, and has potential as a surrogate marker of cardiovascular disease.

Adult↗
PubMed2006

Polymorphism in endothelin-related genes limits exercise-induced decreases in arterial stiffness in older subjects.

Increase in arterial stiffness is associated with aging, which is improved by regular exercise. Endothelin (ET) system has crucial roles in regulating vascular tone and in the progression of atherosclerosis. We hypothesized that molecular variations (ie, gene polymorphisms) in ET-related gene might affect exercise-induced improvement in arterial stiffness with age in human subjects. The present study provides a cross-sectional investigation of 191 healthy middle-aged and older (65+/-1 years) human subjects to clarify the relationship between the regular exercise-induced improvement of arterial stiffness and the gene polymorphisms of ET converting enzyme (ECE)-1, ECE-2, ET-A receptor (ET-A), and ET-B receptor (ET-B). The study subjects were divided into active and inactive groups based on the median value (186 kcal/d) of energy expenditure. Brachial-ankle arterial pulse wave velocity (baPWV) was used to evaluate arterial stiffness. All individuals were genotyped for 4 different polymorphisms of the ET system: 2013(+289)A/G in intron 17 of ECE-1, 669(+17)T/C in intron 5 of ECE-2, 958A/G in exon 6 of ET-A, and 831A/G in exon 4 of ET-B. The baseline baPWV was significantly lower in the active group without any change in blood pressure. Polymorphisms in ECE-1 influenced basal blood pressure. Polymorphisms in ECE-1 and ECE-2 had no effect on baPWV between active and inactive groups. However, polymorphisms in both ET-A and ET-B affected baPWV in the 2 groups. The present results suggest that differences in ET-A and ET-B polymorphisms may influence the response of the vascular wall to exercise whereas ECE-1 polymorphisms may affect basal blood pressure.

Aged↗
PubMed2006

Variations in carotid arterial compliance during the menstrual cycle in young women.

The effect of menstrual cycle phase on arterial elasticity is controversial. In 10 healthy women (20.6+/-1.5 years old, mean+/-s.d.), we investigated the variations in central and peripheral arterial elasticity, blood pressure (carotid and brachial), carotid intima-media thickness (IMT), and serum oestradiol and progesterone concentrations at five points in the menstrual cycle (menstrual, M; follicular, F; ovulatory, O; early luteal, EL; and late luteal, LL). Carotid arterial compliance (simultaneous ultrasound and applanation tonometry) varied cyclically, with significant increases from the values seen in M (0.164+/-0.036 mm2 mmHg-1) and F (0.171+/-0.029 mm2 mmHg-1) to that seen in the O phase (0.184+/-0.029 mm2 mmHg-1). Sharp declines were observed in the EL (0.150+/-0.033 mm2 mmHg-1) and LL phases (0.147+/-0.026 mm2 mmHg-1; F=8.51, P<0.05). Pulse wave velocity in the leg (i.e. peripheral arterial stiffness) did not exhibit any significant changes. Fluctuations in carotid arterial elasticity correlated with the balance between oestradiol and progesterone concentrations. No significant changes were found in carotid and brachial blood pressures, carotid artery lumen diameter, or IMT throughout the menstrual cycle. These data provide evidence that the elastic properties of central, but not peripheral, arteries fluctuate significantly with the phases of the menstrual cycle.

Adolescent↗
PubMed2006

Physical activity duration, intensity, and arterial stiffening in postmenopausal women.

BACKGROUND: Aerobic exercise training is associated with lower central arterial stiffness, but little information exists on the effects of physical activity intensity or duration on central arterial stiffness. Using a cross-sectional and interventional approach, we tested the hypothesis that both moderate and vigorous physical activity reduce central arterial stiffness in postmenopausal women. METHODS: Carotid arterial stiffness (via ultrasound and applanation tonometry) and duration of physical activity at low, moderate, and vigorous intensities (via electronic accelerometer) were measured in 103 apparently healthy sedentary or recreationally active women 47 to 82 years of age. Moderate intensity physical activity was defined as 4.0 to 6.0 metabolic equivalents (MET) in subjects aged <65 years and as 3.0 to 5.0 MET in subjects >or=65 years. A subgroup of 17 sedentary subjects was randomly assigned to moderate (n = 8) or vigorous (n = 9) intensity cycling exercise training (900 kcal/week, three to five sessions per week, for 12 weeks). Carotid arterial stiffness was measured before and after training. RESULTS: Carotid beta-stiffness index was significantly correlated with the duration of moderate and vigorous intensity physical activity (r = -0.25 and r = -0.22) even after adjustment for age, height, and mean BP. Carotid beta-stiffness index significantly decreased after moderate and vigorous intensity cycling training. There were no significant group differences in the magnitude of beta-stiffness index change even after adjustment for expected confounders (eg, baseline beta-stiffness index, height, body mass index, heart rate, and post-training body mass, body mass index, and mean BP). CONCLUSIONS: These results suggest that both moderate and vigorous physical activities have favorable effects on central arterial stiffness in postmenopausal women.

Aged↗
PubMed2006

Age-related reduction of systemic arterial compliance induces excessive myocardial oxygen consumption during sub-maximal exercise.

Reduction of systemic arterial compliance (SAC) with aging increases left ventricular afterload. The present study was designed to examine whether age-related reduction of SAC is related to excessive myocardial oxygen consumption during sub-maximal aerobic exercise. We studied elderly (60-69 years; n = 25) and senior (70-82 years; n = 25) subjects. We measured SAC immediately before the start of the ramp-fashion exercise (i.e., at the end of the 20 W warm-up exercise) and the double product (DP: systolic blood pressure x heart rate) during the ramp-fashion exercise (20-50 W). SAC was significantly lower in senior subjects (0.76 +/- 0.25 ml mmHg(-1) m(-2)) compared with elderly subjects (0.95 +/- 0.22 ml mmHg(-1) m(-2)). DP was higher in senior subjects (20 W: 14.3 +/- 3.1; 30 W: 15.9 +/- 4.2; 40 W: 17.7 +/- 4.9; 50 W: 20.6 +/- 5.6 [x 10(3) mmHg bpm]) than in elderly subjects (12.8 +/- 3.0, 14.0 +/- 3.5, 15.1 +/- 4.0, 17.1 +/- 4.3 [x 10(3) mmHg bpm]). In total subjects, SAC correlated significantly with DP (r = -0.64, r = -0.64, r = -0.64, r = -0.64). In senior subjects, SAC was related significantly to DP (r = -0.83, r = -0.78, r = -0.76, r = -0.74). In elderly subjects, SAC tended to correlate with DP although its relationships were not statistically significant (r = -0.34, r = -0.36, r = -0.33, r = -0.31). Correlation coefficients at each respective exercise intensity were significantly higher in senior subjects compared with elderly subjects. These results suggest that the age-related reduction of SAC is related to excessive myocardial oxygen consumption during sub-maximal aerobic exercise in older humans, but this relation does not become significant until the SAC reduction becomes pronounced.

Age Factors↗
PubMed2005

Effects of short-term endurance training on aortic distensibility in young males.

BACKGROUND: Short-term endurance exercise training can increase aortic distensibility. The effect of exercise on arterial distensibility, however, may not last long term. PURPOSE: We evaluated the effects of short-term exercise training and detraining on aortic distensibility in 10 sedentary young males (21.0 +/- 0.6 yr, mean +/- SE; range 19-24 yr). METHODS: The subjects underwent 8 wk of endurance training on a cycle ergometer at 70% of maximal oxygen consumption (VO(2max)), for 60 min at a time and on alternate days (3-4 d.wk(-1). The detraining period consisted of a return to sedentary days for 8 wk. The aortic pulse wave velocity (APWV) was measured before and immediately after training and during the detraining period. RESULTS: The VO(2max) was significantly increased after training (pre: 2240.0 +/- 71.4 mL, after: 2728.8 +/- 82.5 mL, mean +/- SE, P < 0.0001) and remained at increased levels during the detraining period (after 4 wk: 2671.2 +/- 73.6 mL, P < 0.001; after 8 wk: 2628.0 +/- 85.0 mL, P < 0.001). The APWV was significantly decreased after training (pre: 5.80 +/- 0.15 m.s(-1), after: 5.50 +/- 0.21 m.s(-1), P < 0.01) but returned close to the baseline after detraining for 4 wk (5.66 +/- 0.13 m.s, P < 0.18). CONCLUSION: Our data suggest that short-term exercise training can improve aortic distensibility, but the effect cannot be maintained without continuing physical exercise.

Adult↗
PubMed2005

Effect of arterial lumen enlargement on carotid arterial compliance in normotensive postmenopausal women.

A reduction in central arterial compliance has been identified as an independent risk factor for future cardiovascular disease. The aim of the present study was to determine the influence of age-related carotid arterial enlargement on carotid arterial compliance in postmenopausal females, using a cross-sectional study design. Carotid arterial properties were measured with applanation tonometry and ultrasound system in 113 normotensive females (aged 50-78). Brachial-ankle pulse wave velocity (baPWV) measured by a plethysmographic technique was used as an index of arterial stiffness. In comparisons among the three age groups (50-59, 60-69, and 70-78 years old), baPWV (F=11.9, p<0.001) and carotid systolic (F=4.5, p<0.05) and pulse pressures (F=9.6, p<0.0001), and lumen diameter (F=5.6, p<0.01) increased with advancing age. Carotid arterial compliance gradually decreased with age, but not significantly. A stepwise regression analysis revealed that carotid systolic pressure and lumen diameter and age were independent correlates of carotid arterial compliance. After carotid lumen diameter was taken into account (ANCOVA), the differences in carotid arterial compliance among the three age groups became significant (F=3.8, p<0.05). These results suggest that an increase in arterial lumen diameter might compensate for the age-related increase in arterial stiffness and limit the deterioration of the buffering capacity of the central artery in normotensive postmenopausal females.

Adaptation, Physiological↗
PubMed2004

Unfavorable effects of resistance training on central arterial compliance: a randomized intervention study.

BACKGROUND: Reductions in the compliance of central arteries exert a number of adverse effects on cardiovascular function and disease risk. Endurance training is efficacious in increasing arterial compliance in healthy adults. We determined the effects of resistance training on carotid arterial compliance using the intervention study design. METHODS AND RESULTS: Twenty-eight healthy men 20 to 38 years old were randomly assigned to the intervention group (n=14) and the control group (n=14). Control subjects were instructed not to alter their normal activity levels throughout the study period. Intervention subjects underwent 3 supervised resistance training sessions per week for 4 months and detraining for a subsequent 4 months. The resistance training increased maximal strength in all muscle groups tested (P<0.001). There were no significant differences in baseline arterial compliance and beta-stiffness index between the intervention and control groups. In the intervention group, carotid arterial compliance decreased 19% (P<0.05), and beta-stiffness index increased 21% (P<0.01) after resistance training. These values returned completely to the baseline levels during the detraining period. Arterial compliance did not change in the control group. In both groups, there were no significant changes in brachial and carotid blood pressure, carotid intima-media thickness, lumen diameter, and femoral arterial compliance. Changes in carotid artery compliance were significantly and negatively related to corresponding changes in left ventricular mass index (r=-0.56, P<0.001) and left ventricular hypertrophy index (r=-0.68, P<0.001). CONCLUSIONS: In marked contrast to the beneficial effect of regular aerobic exercise, several months of resistance training "reduces" central arterial compliance in healthy men.

Adult↗
PubMed2004

Effects of nitric oxide synthase inhibitor on decrease in peripheral arterial stiffness with acute low-intensity aerobic exercise.

We previously reported that even low-intensity, short-duration acute aerobic exercise decreases arterial stiffness. We aimed to test the hypothesis that the exercise-induced decrease in arterial stiffness is caused by the increased production of NO in vascular endothelium with exercise. Nine healthy men (age: approximately 22-28 yr) performed a 5-min single-leg cycling exercise (30 W) in the supine position under an intravenous infusion of NG-monomethyl-L-arginine (L-NMMA; 3 mg/kg during the initial 5 min and subsequent continuous infusion of 50 mug.kg(-1).min(-1) in saline) or vehicle (saline) in random order on separate days. The pulse wave velocity (PWV) from the femoral to posterior tibial artery was measured on both legs before and after the infusion at rest and 2 min after exercise. Under the control condition, exercised leg PWV significantly decreased after exercise (P <0.05), whereas nonexercised leg PWV did not show a significant change throughout the experiment. Under L-NMMA administration, exercised leg PWV was increased significantly by the infusion (P <0.05) but decreased significantly after the exercise (P <0.05). Nonexercised leg PWV increased with L-NMMA administration and maintained a significantly higher level during the administration compared with baseline (before the infusion, all P <0.05). The NO synthase blockade x time interaction on exercised leg PWV was not significant (P=0.706). These results suggest that increased production of NO is not a major factor in the decrease of regional arterial stiffness with low-intensity, short-duration aerobic exercise.

Adult↗
PubMed2004

Resistance exercise training reduces plasma endothelin-1 concentration in healthy young humans.

Endothelin-1 (ET-1), which is produced by vascular endothelial cells, has potent vasoconstrictor and proliferative activity in vascular smooth muscle cells, and therefore has been implicated in regulation of vascular tonus and progression of atherosclerosis. We recently demonstrated that the plasma ET-1 concentration was significantly decreased by aerobic exercise training in healthy young humans and healthy older humans. However, it is unclear whether the production of ET-1 is altered by resistance exercise training. We measured the plasma ET-1 concentration before and after resistance exercise training in healthy young humans. Six healthy young men (26 +/- 1 years old) performed 8 weeks of resistance exercise training (3 days/week). There were no significant differences in body composition, blood pressure, heart rate, and maximal oxygen consumption before and after resistance exercise training. The girths of the arm and thigh significantly increased after resistance exercise training. The maximal muscle powers in the arm and leg increased after resistance exercise training. After resistance exercise training, the plasma concentration of ET-1 significantly decreased. The present study suggested that resistance exercise training, as well as aerobic exercise training, reduces the plasma ET-1 concentration in healthy young humans, and that this reduction in plasma ET-1 concentration may have beneficial effects on the cardiovascular system.

Adaptation, Physiological↗
PubMed2004

Reductions in basal limb blood flow and lumen diameter after short-term leg casting.

PURPOSE: We tested the hypotheses that short-term casting immobilization of a leg would reduce basal blood flow and vascular conductance and induces structural alterations in femoral artery. METHODS: Right knee and ankle joints of eight healthy young men were immobilized with casting for 7 d. Before and immediately after casting, and 14 d after the cast was removed, femoral artery hemodynamics and structure were measured using a high-resolution ultrasound. RESULTS: Femoral artery lumen diameter in the immobilized leg decreased after the immobilization (P < 0.05) and returned to baseline during the recovery period, in which the subjects did not receive any special rehabilitation treatment. Femoral artery intima-media thickness (IMT) and IMT/lumen ratio in both legs did not show significant changes throughout the interventions. In the immobilized leg, femoral artery blood flow and vascular conductance decreased (-23 to 24%) after the immobilization (all P < 0.05). These parameters returned to the baseline during the recovery period, and there were no significant differences between the baseline and recovery values. In the control leg, femoral blood flow and vascular conductance did not change throughout the investigation. After 7 d of casting, femoral arterial distension, an index of arterial distensibility, tended to decrease in the immobilized leg but not in the control leg. CONCLUSION: We concluded that a short-term immobilization of lower limb decreases basal limb blood flow and arterial lumen diameter. These results suggest that basal limb blood flow and lumen diameter decrease rapidly upon the cessation of muscular weight bearing and locomotor activity, and may be modulated by an ordinary level of physical activity.

Adult↗
PubMed2004

Effect of low-intensity aerobic exercise training on arterial compliance in postmenopausal women.

Regular aerobic exercise training attenuates age-related reduction in central arterial compliance, an independent risk factor of cardiovascular diseases. We tested the hypothesis that even low-intensity exercise training could increase central arterial compliance in postmenopausal women. Using B-mode ultrasound, we studied the central arterial compliance of 15 postmenopausal females (age: 52-66 years) before and after a 12-week aerobic exercise intervention. Subjects performed aerobic exercise training of the same energy expenditure (cycle exercise, total 900 kcal/week, 3-5 sessions/week) at two different exercise intensities: 7 trained at low intensity (40% heart rate reserve: L-TR) and 8 trained at moderate intensity (70% heart rate reserve: M-TR). Arterial compliance increased after exercise training in the L-TR group (0.70+/-0.32 vs. 1.06+/-0.55 mm2/mmHgX10(-1), p <0.05) and in the M-TR group (0.82+/-0.37 vs. 1.14+/-0.39 mm2/mmHgX10(-1), p <0.05). There was no significant difference in increases of arterial compliance in either group (L-TR: 0.35+/-0.38 vs. M-TR: 0.32+/-0.33 mm2/mmHgX10(-1)). These results suggest that the improvement of central arterial compliance by aerobic exercise training might not be influenced by the intensity of exercise training if the energy expenditure of the training is the same. Accordingly, even low-intensity exercise training may have the effect of improving central arterial compliance.

Carotid Arteries↗
PubMed2004

Moderate regular exercise increases basal production of nitric oxide in elderly women.

Vascular endothelial cells produce nitric oxide (NO), which is a potent vasodilator substance and is thought to have antiatherosclerotic properties. Therefore, it has also been proposed that NO may be useful to regulate vascular tonus and prevent progression of atherosclerosis. On the other hand, NO activity reduces with aging. We previously reported that the plasma nitrite/nitrate (NOx: the stable end product of NO) concentration was significantly increased by intense aerobic exercise training in healthy young humans. We hypothesized that lifestyle modification (e.g., even mild regular exercise training) can increase NO production in previously sedentary older humans. We measured the plasma NOx concentration before and after a mild aerobic exercise training regimen (cycling on a leg ergometer at 80% ventilatory threshold for 30 min, 5 days/week) for 3 months in elderly women. In addition, we assessed the plasma concentration of cyclic guanosine monophosphate (cGMP), a second messenger of NO, in the same samples. The individual ventilatory threshold increased significantly after the 3-month exercise training. The blood pressure at rest significantly decreased after exercise training. These results suggest that the 3-month exercise training in the older women produced favorable physiological effects. The plasma concentration of NOx significantly increased by the exercise training, and the plasma concentration of cGMP also increased by the exercise training. The present study suggests that even a mild regular aerobic-endurance exercise increases NO production in previously sedentary older humans, which may have beneficial effects (i.e., antihypertensive and antiatherosclerotic effects by endogenous NO) on the cardiovascular system.

Aged↗
PubMed2003

Aerobic exercise training reduces plasma endothelin-1 concentration in older women.

Endothelial function deteriorates with aging. On the other hand, exercise training improves the function of vascular endothelial cells. Endothelin-1 (ET-1), which is produced by vascular endothelial cells, has potent constrictor and proliferative activity in vascular smooth muscle cells and, therefore, has been implicated in regulation of vascular tonus and progression of atherosclerosis. We previously reported significantly higher plasma ET-1 concentration in middle-aged than in young humans, and recently we showed that plasma ET-1 concentration was significantly decreased by aerobic exercise training in healthy young humans. We hypothesized that plasma ET-1 concentration increases with age, even in healthy adults, and that lifestyle modification (i.e., exercise) can reduce plasma ET-1 concentration in previously sedentary older adults. We measured plasma ET-1 concentration in healthy young women (21-28 yr old), healthy middle-aged women (31-47 yr old), and healthy older women (61-69 yr old). The plasma level of ET-1 significantly increased with aging (1.02 +/- 0.08, 1.33 +/- 0.11, and 2.90 +/- 0.20 pg/ml in young, middle-aged, and older women, respectively). Thus plasma ET-1 concentration was markedly higher in healthy older women than in healthy young or middle-aged women (by approximately 3- and 2-fold, respectively). In healthy older women, we also measured plasma ET-1 concentration after 3 mo of aerobic exercise (cycling on a leg ergometer at 80% of ventilatory threshold for 30 min, 5 days/wk). Regular exercise significantly decreased plasma ET-1 concentration in the healthy older women (2.22 +/- 0.16 pg/ml, P < 0.01) and also significantly reduced their blood pressure. The present study suggests that regular aerobic-endurance exercise reduces plasma ET-1 concentration in older humans, and this reduction in plasma ET-1 concentration may have beneficial effects on the cardiovascular system (i.e., prevention of progression of hypertension and/or atherosclerosis by endogenous ET-1).

Adult↗
PubMed2003

The effects of low-intensity single-leg exercise on regional arterial stiffness.

We examined the effect of low-intensity single-leg exercise (20 or 30 watt, 5 min) on pulse wave velocity from the femoral to the ankle arteries in 18 young men. After the exercise, the velocity significantly decreased in the exercised leg, but not in the counterpart, suggesting that the decrease in arterial stiffness in the exercised leg was induced mainly by exercise-related regional factors.

Adult↗
PubMed2002

Age-related reductions in appendicular skeletal muscle mass: association with habitual aerobic exercise status.

Appendicular skeletal muscle mass decreases with advancing age, and this is thought to be a key factor for reductions in functional independence in the elderly. We determined the potential modulatory influence of regular aerobic exercise on the age-related reductions in appendicular muscle mass. In the present cross-sectional study, we studied a total of 131 healthy men aged 20-79 years. For at least the previous 2 years subjects were either sedentary or endurance-trained. Appendicular skeletal muscle mass was measured using dual-energy X-ray absorptiometry. There were no significant group differences in height. Body mass and body surface area were lower in endurance-trained compared with sedentary men (P<0.05). In general, body fat increased with age in both groups, but was lower in endurance-trained compared with sedentary men at any age group (P<0.05). Lean body mass and maximal oxygen consumption decreased with age (P<0.05). Irrespective of expression (absolute, relative to body surface area, or relative to body mass), arm, leg, and total limb muscle mass generally decreased with age. Absolute appendicular muscle mass was not different between the two activity groups. When expressed relative to body mass or body surface area, appendicular muscle mass in the endurance-trained middle-aged and older men was significantly higher than their sedentary peers. The rate of decline in appendicular muscle mass with age was similar between the two activity groups. The results of the present cross-sectional study indicate that endurance-trained men had significantly higher appendicular skeletal muscle mass relative to body mass or body size compared with their sedentary peers. This may contribute, at least in part, to the lower incidence of functional disability observed in middle-aged and older men who exercise regularly.

Absorptiometry, Photon↗