Adverse effects of coexistence of sarcopenia and metabolic syndrome in Japanese women.

BACKGROUND/OBJECTIVES: Little information is available regarding the interactions of sarcopenia and metabolic syndrome (MetS) in the risks of these age-associated diseases in women. The present cross-sectional study was performed to investigate whether the coexistence of sarcopenia and MetS further increases the risks of lifestyle-related diseases in Japanese women. SUBJECTS/METHODS: Healthy Japanese women (n=533) aged 30-84 participated in this study. MetS was defined as higher body mass index, fasting plasma glucose, systolic or diastolic blood pressure and blood lipid abnormalities. Appendicular muscle mass and bone mineral density (BMD) were measured using dual-energy X-ray absorptiometry. The criterion of low muscle mass and strength defined median skeletal muscle index (appendicular muscle mass/height², kg/m²) and handgrip strength. RESULTS: Two-way ANCOVA with adjustment for age, body fat percentage and whole-body lean tissue mass indicated that sarcopenia and MetS interacted to produce a significant effect on HbA1c, systolic blood pressure, triglycerides and brachial-ankle pulse wave velocity in Japanese women. The systolic blood pressure, triglycerides and brachial-ankle pulse wave velocity were significantly higher in women with coexisting sarcopenia and MetS than in healthy controls or in those with sarcopenia or MetS alone. The HbA1c in the coexisting sarcopenia and MetS group was higher than in healthy controls and sarcopenia subjects. CONCLUSIONS: The coexistence of sarcopenia and MetS further increases the risks of cardiovascular diseases, such as type 2 diabetes mellitus, hypertension, arterial stiffness and hyperlipidemia even adjustment of age and body composition in adult Japanese women.

Accelerometer-determined physical activity level among government employees in Penang, Malaysia.

INTRODUCTION: A cross-sectional study was carried out to investigate accelerometer-determined physical activity level of 233 Malay government employees (104 men, 129 women) working in the Federal Government Building Penang, Malaysia. METHODS: Body weight, height, waist and hip circumference, body fat percentage and blood pressure were measured for each respondent. All the respondents were asked to wear an accelerometer for 3 days. Body mass index (BMI) and waist-hip ratio (WHR) were calculated using a standard formulas. Fasting blood sample was obtained to determine the lipid profile and glucose levels of the respondents. RESULTS: Based on the accelerometer-determined physical activity level, almost 65% of the respondents were categorised as sedentary. Approximately 50.2% of the respondents were overweight or obese. There were negative but significant relationships between body mass index (BMI) (r = -0.353, p < 0.05), body fat percentage (r = -0.394, p < 0.05), waist circumference (WC) (r = -0.198, p < 0.05) and physical activity level. Sedentary individuals had a higher risk than moderate to active individuals of having a BMI more than or equal to 25 kg/m2 (OR = 2.80, 95% CI 1.55-5.05), an-risk classified WC (OR = 1.79, 95% CI 1.01-3.20), and a body fat percentage classified as unhealthy (OR = 3.01, 95% CI 1.41-6.44). CONCLUSION: The results of this study suggest that accelerometer-determined physical activity level is a significant factor associated with obesity in this study. The high prevalence of physical inactivity and obesity found among respondents of this study indicate a need for implementing intervention programmes among this population.

A cross-sectional study of sarcopenia in Japanese men and women: reference values and association with cardiovascular risk factors.

In this study of Japanese men and women, we determine reference values for sarcopenia and test the hypothesis that sarcopenia is associated with risk factors for cardiovascular disease, independent of waist circumference. A total of 1,488 Japanese men and women aged 18-85 years participated in this study. Appendicular muscle mass (AMM) was measured by dual-energy X-ray absorptiometry. Reference values for classes 1 and 2 sarcopenia (skeletal muscle index: AMM/height2, kg m-2) in each sex were defined as values one and two standard deviations below the sex-specific means of reference values obtained in this study from young adults aged 18-40 years. The reference values for class 1 and class 2 sarcopenia were 7.77 and 6.87 kg m-2 in men and 6.12 and 5.46 kg m-2 in women. In subjects both with class 1 and class 2 sarcopenia, body mass index and % body fat were significantly lower than in normal subjects. Despite whole-blood glycohaemoglobin A1c in men with class 1 sarcopenia was significantly higher than in normal subjects, and brachial-ankle pulse wave velocity in women both with class 1 and class 2 sarcopenia were significantly higher than in normal subjects, using one-way ANCOVA with adjustment for the covariate of waist circumference. Although sarcopenia is associated with thin body mass, it is associated with more glycation of serum proteins in men and with greater arterial stiffness in women, independent of waist circumference.

Age and cardiorespiratory fitness are associated with arterial stiffening and left ventricular remodelling.

Arterial stiffening, hypertension and left ventricular (LV) remodelling are associated with increased risk of cardiovascular disease. Cardiorespiratory fitness is associated with cardiovascular function and reduced risk of cardiovascular disease. This cross-sectional study was carried out to determine the relationships between cardiorespiratory fitness, arterial stiffness, blood pressure (BP) and LV remodelling in women. On the basis of peak oxygen uptake, a total of 159 premenopausal (young) and postmenopausal (older) women were categorized into either low (unfit) or high (fit) cardiorespiratory fitness groups. The arterial stiffness and LV remodelling were measured by brachial-ankle pulse wave velocity (baPWV) and carotid augmentation index (AI) and LV relative wall thickness (RWT). Two-way analysis of variance indicated a significant interaction between age and cardiorespiratory fitness in baPWV, carotid AI, BP and RWT. In the older group, arterial stiffness (baPWV; 1401+/-231 vs 1250+/-125 cm s(-1), P<0.01, AI; 32.9+/-9.9 vs 24.8+/-10.1%, P<0.01), systolic blood pressure (SBP) (130+/-22 vs 117+/-15 mm Hg, P<0.01) and RWT (0.47+/-0.08 vs 0.42+/-0.04, P<0.05) in fit women were lower than in unfit women. In older women, RWT was significantly related to baPWV (r=0.46, P<0.01), carotid AI (r=0.29, P<0.05), SBP (r=0.57, P<0.01) \[V(2peak) (r=-0.32, P<0.05). In young women, they were not significant correlations, except for a weak correlation between RWT and SBP (r=0.21, P<0.05). These results suggest that higher cardiorespiratory fitness is associated with lower arterial stiffness, BP and RWT in older women.

Muscle mass and bone mineral indices: does the normalized bone mineral content differ with age?

OBJECTIVE: To investigate the relationships between regional skeletal muscle mass (SM mass) and bone mineral indices and to examine whether bone mineral content (BMC) normalized to SM mass shows a similar decrease with age in young through old age. SUBJECTS/METHODS: One hundred and thirty-eight young and postmenopausal women aged 20-76 years participated in this study and were divided into three groups: 61 young women, 49 middle-aged postmenopausal women and 28 older postmenopausal women. Muscle thickness (MTH) was determined by ultrasound, and regional SM mass (arm, trunk and leg) was estimated based on nine sites of MTH. Whole-body and regional lean soft tissue mass (LSTM), bone mineral density (BMD) and BMC (whole body, arms, legs and lumbar spine) were measured using dual-energy X-ray absorptiometry. RESULTS: Ultrasound spectroscopy indicated that SM mass is significantly correlated with site-matched regional bone mineral indices and these relationships correspond to LSTM. The BMC and BMD in older women were significantly lower than those in middle-aged women. When BMC was normalized to site-matched regional SM mass, BMC normalized to SM mass in arm and trunk region were significantly different with age; however, whole-body and leg BMC normalized to SM mass showed no significant difference between middle-aged and older postmenopausal women. CONCLUSIONS: The age-related differences in BMC were found to be independent of the ageing of SM mass in the arm and trunk region. However, differences in BMC measures of the leg and whole body were found to correspond to age-related decline of SM mass in postmenopausal women.

Resting energy expenditure can be assessed by dual-energy X-ray absorptiometry in women regardless of age and fitness.

OBJECTIVE: To evaluate the possibility that measurement of the magnitude and distribution of fundamental somatic heat-producing units using dual-energy X-ray absorptiometry (DXA) can be used to estimate resting energy expenditure (REE) in both young and elderly women with different aerobic fitness levels. SUBJECTS AND METHODS: Peak oxygen uptake (VO(2) peak) and REE(m) were directly measured in 116 young (age: 22.3+/-2.1 years) and 72 elderly (63.3+/-6.4 years) women. The subjects were divided into four groups according to categories of age and VO(2) peak; young: high fitness (YH, n=58); low fitness (YL, n=58); elderly: high fitness (EH, n=37) and low fitness (EL, n=35). Using DXA, systemic and regional body compositions were measured, and REE(e) was estimated from the sum of tissue organ weights multiplied by corresponding metabolic rate. RESULTS: Although there were remarkable differences in systemic and regional body compositions, no significant differences were observed between REE(m) and REE(e) in the four groups. REE(e) significantly correlated with REE(m) in elderly as well as young women; the slopes and intercepts of the two regression lines were statistically not different between the elderly and young groups (elderly: y=0.60x + 472, r=0.667; young: y=0.78x + 250, r=0.798; P<0.001, respectively). A Bland-Altman analysis did not indicate bias in calculation of REE for all the subjects. CONCLUSION: These results suggest that REE can be estimated from tissue organ components in women regardless of age and aerobic fitness.

Physical activity level in healthy free-living Japanese estimated by doubly labelled water method and International Physical Activity Questionnaire.

OBJECTIVE: To measure total energy expenditure (TEE) for normal healthy Japanese by the doubly labelled water (DLW), and to compare the physical activity level (PAL) among categories classified by the categories used in daily reference intake (DRI), Japan and the International Physical Activity Questionnaire (IPAQ). SUBJECTS AND METHODS: A total of 150 healthy Japanese men and women aged 20- to 59-year-old living in four districts of Japan. TEE was measured by the DLW method, and the PAL was calculated from TEE divided by basal metabolic rate. Simultaneously with TEE measurement, the PAL was assessed employing the categories used in DRI, Japan and IPAQ. RESULTS: The average TEE and PAL were 10.78+/-1.67 MJ/day and 1.72+/-0.22 for males and 8.37+/-1.30 MJ/day and 1.72+/-0.27 for females, respectively. The subjects in the highly active categories assessed by both DRI and IPAQ showed significantly higher PAL compared with less active categories. However, PALs among light and moderate categories by DRI, and insufficient and sufficiently active by IPAQ were not significantly different. CONCLUSIONS: In developed countries, highly active subjects could be assessed by a simple questionnaire. However, the questionnaire should be improved to clarify the sedentary to moderately active subjects by assessing carefully very light to moderate physical activity.

Validation of self-reported energy intake by a self-administered diet history questionnaire using the doubly labeled water method in 140 Japanese adults.

OBJECTIVE: To validate reported energy intake (rEI) with a self-administered diet history questionnaire (DHQ) against total energy expenditure (TEE) by the doubly labeled water (DLW) method. SUBJECTS: A total of 140 healthy Japanese adults (67 men and 73 women) aged 20-59 years living in four areas in Japan. METHODS: Energy intake was assessed twice with DHQ over a 1-month period before and after TEE measurement (rEI(DHQ1) and rEI(DHQ2), respectively). TEE was measured by DLW during 2 weeks (TEE(DLW)). RESULTS: Mean rEI(DHQ1) was lower than those of TEE(DLW) by 1.9+/-2.4 MJ/day (16.4%, P<0.001) for men and 0.6+/-1.9 MJ/day (6.0%, P<0.01) for women. In men and women together, 62 subjects (44%) were defined as underreporters (rEI(DHQ1)/TEE(DLW) <0.84), 58 (41%) as acceptable reporters (0.84-1.16) and 20 (14%) as over-reporters (>1.16). Pearson correlation coefficient was 0.34 for men and 0.22 for women. After adjustment for the dietary and non-dietary factors related to rEI(DHQ1)/TEE(DLW), the correlation coefficient improved to 0.42 and 0.37, respectively. CONCLUSION: The energy intake assessed with DHQ correlated low to modestly with TEE measured by DLW. In addition, DHQ underestimated energy intake at a group level. Caution is needed when energy intake was evaluated by DHQ at both individual and group levels.

A dose-response relation between aerobic exercise and visceral fat reduction: systematic review of clinical trials.

OBJECTIVE: It has been suggested that exercise has preferential effects on visceral fat reduction. However, the dose-response effect remains unclear because of limited evidence from individual studies. The purpose of this study was to systematically review the current literature to establish whether reduction of visceral fat by aerobic exercise has a dose-response relationship. METHODS: A database search was performed (PubMed, 1966-2006) with appropriate keywords to identify studies exploring the effects of aerobic exercise as a weight loss intervention on visceral fat reduction. Visceral fat reduction was expressed as the percentage of visceral fat change per week (%DeltaVF/w). The energy expenditure by aerobic exercise was expressed as Sigma (metabolic equivalents x h per week (METs x h/w)). RESULTS: Nine randomized control trials and seven non-randomized control trials were selected. In most of the studies, the subjects performed aerobic exercise generating 10 METs x h/w or more. Among all the selected groups (582 subjects), visceral fat decreased significantly (P<0.05) in 17 groups during the intervention, but not in the other 4 groups. There was no significant relationship between METs x h/w from aerobic exercise and %DeltaVF/w in all the selected groups. However, when subjects with metabolic-related disorders were not included (425 subjects), METs x h/w from aerobic exercise had a significant relationship with %DeltaVF/w (r=-0.75). Moreover, visceral fat reduction was significantly related to weight reduction during aerobic exercise intervention, although a significant visceral fat reduction may occur without significant weight loss. CONCLUSION: These results suggest that at least 10 METs x h/w in aerobic exercise, such as brisk walking, light jogging or stationary ergometer usage, is required for visceral fat reduction, and that there is a dose-response relationship between aerobic exercise and visceral fat reduction in obese subjects without metabolic-related disorders.

Interindividual variability in sleeping metabolic rate in Japanese subjects.

INTRODUCTION: Basal metabolic rate (BMR) or sleeping metabolic rate (SMR) is the largest component of total energy expenditure (EE). An accurate prediction of BMR or SMR is needed to accurately predict total EE or physical activity EE for each individual. However, large variability in BMR and SMR has been reported. OBJECTIVES: This study was designed to develop prediction equations using body size measurements for the estimation of both SMR and BMR and to compare the prediction errors with those in previous reports. METHODS: We measured body size, height, weight and body composition (fat mass and fat-free mass) from skinfold thickness in adult Japanese men (n=71) and women (n=66). SMR was determined as the sum of EE during 8 h of sleep (SMR-8h) and minimum EE during 3 consecutive hours of sleep (SMR-3h) measured using two open-circuit indirect human calorimeters. BMR was determined using a human calorimeter or a mask and Douglas bag. RESULTS: The study population ranged widely in age. The SMR/BMR ratio was 1.01+/-0.09 (range 0.82-1.42) for SMR-8h and 0.94+/-0.07 (range 0.77-1.23) for SMR-3h. The prediction equations for SMR accounted for a 3-5% larger variance with 2-3% smaller standard error of estimate (SEE) than the prediction equations for BMR. DISCUSSION: SMR can be predicted more accurately than previously reported, which indicates that SMR interindividual variability is smaller than expected, at least for Japanese subjects. The prediction equations for SMR are preferable to those for BMR because the former exhibits a smaller prediction error than the latter.

Effects of high-intensity intermittent swimming on PGC-1alpha protein expression in rat skeletal muscle.

AIM: The aim of the present investigation was to elucidate the effects of exercise intensity on exercise-induced expression of peroxisome proliferator-activated receptor gamma coactivator-1alpha (PGC-1alpha) protein in rat skeletal muscle. METHODS: We measured PGC-1alpha content in the skeletal muscles of male Sprague-Dawley rats (age: 5-6 weeks old; body weight: 150-170 g) after a single session of high-intensity intermittent exercise (HIE) or low-intensity prolonged swimming exercise (LIE). During HIE, the rats swam for fourteen 20-s periods carrying a weight (14% of body weight), and the periods of swimming were separated by a 10-s pause. LIE rats swam with no load for 6 h in two 3-h sessions, separated by 45 min of rest. RESULTS: After HIE, the PGC-1alpha protein content in rat epitrochlearis muscle had increased by 126, 140 and 126% at 2, 6 and 18 h, respectively, compared with that of the age-matched sedentary control rats' muscle. Immediately, 6 and 18-h after LIE, the PGC-1alpha protein content in the muscle was significantly elevated by 84, 95 and 67% respectively. The PGC-1alpha protein content observed 6 h after HIE tended to be higher than that observed after LIE. However, there was no statistically significant difference between the two values (P = 0.12). CONCLUSION: The present investigation suggests that irrespective of the intensity of the exercise, PGC-1alpha protein content in rat skeletal muscle increases to a comparable level when stimuli induced by different protocols are saturated. Further, HIE is a potent stimulus for enhancing the expression of PGC-1alpha protein, which may induce mitochondrial biogenesis in exercise-activated skeletal muscle.

Effects of 20 days of bed rest on the viscoelastic properties of tendon structures in lower limb muscles.

OBJECTIVES: The purpose of this study was to investigate the effects of 20 days' bed rest on the viscoelastic properties of human tendon structures in knee extensor and plantar flexor muscles in vivo. METHODS: Eight healthy men (age: 24+/-4 years, height: 172+/-9 m, body mass: 69+/-13 kg) carried out a 6 degrees head-down bed rest for 20 days. Before and after bed rest, elongation (L) of the tendon and aponeurosis of vastus lateralis (VL) and medial gastrocnemius muscles (MG) during isometric knee extension and plantar flexion, respectively, were determined using real-time ultrasonic apparatus, while the subjects performed ramp isometric contraction up to the voluntary maximum, followed by ramp relaxation. The relationship between estimated muscle force (Fm) and tendon elongation (L) was fitted to a linear regression, the slope of which was defined as stiffness. The hysteresis was calculated as the ratio of the area within the Fm-L loop to the area beneath the load portion of the curve. RESULTS: L values above 100 N were significantly greater after bed rest for VL, while there were no significant differences in L values between before and after for MG. The stiffness decreased after bed rest for VL (70.3+/-27.4 v 50.1+/-24.8 N/mm, before and after bed rest, respectively; p = 0.003) and MG (29.4+/-7.5 v 25.6+/-7.8 N/mm, before and after bed rest, respectively; p = 0.054). In addition, hysteresis increased after bed rest for VL (16.5+/-7.1% v 28.2+/-12.9%, before and after bed rest, respectively; p = 0.017), but not for MG (17.4+/-4.4% v 17.7+/-6.1%, before and after bed rest, respectively; p = 0.925). CONCLUSIONS: These results suggested that bed rest decreased the stiffness of human tendon structures and increased their hysteresis, and that these changes were found in knee extensors, but not the plantar flexors.

A study of inter-alpha-trypsin inhibitor chains expression in liposarcomas.

AIM: Liposarcoma is common soft tissue sarcoma that is sometimes difficult to treat, besides its good prognosis. The inter-alpha-trypsin inhibitor heavy chains (HCs) has been reported to be linked to hyaluronan, which play important roles in tumour progression and metastasis. In this study, clinical significance of HCs in patients with liposarcoma was investigated. METHODS: HC expression was studied by immunohistochemistry on resected specimens of 33 liposarcoma patients and 10 lipoma patients. The expression of HC mRNA was analyzed by reverse transcription polymerase chain reaction (RT-PCR). Serum concentration of HC was determined with enzyme-linked immunosorbent assay (ELISA). RESULTS: Prominent positive staining of HC was observed in extracellular matrix of pleomorphic and myxoid liposarcoma. In well-differentiated liposarcoma and lipoma, faint staining was seen with HC. No products of HC could be detected by RT-PCR. Serum concentration of HC was not up-regulated in any subtypes of liposarcoma. HC expression was not significantly correlated with tumour subtypes and prognosis. CONCLUSION: HC was strongly accumulated in pleomorphic and myxoid liposarcoma, however, was not locally synthesized in liposarcoma. HC might play roles in stabilizing extracellular matrix, such as hyaluronan (HA), in liposarcoma.

Stimulated type I collagen turnover in patients with giant cell tumor of bone.

The aim of this study was to determine type I collagen turnover in giant cell tumor of bone (GCT) by biochemical markers of type I procollagen aminoterminal propeptide (PINP) and type I collagen carboxyterminal telopeptide (ICTP) as synthesis and degradation markers, respectively. The serum concentrations of PINP and ICTP were measured in 11 patients with GCT using radioimmunoassay, and analyzed by the correlation to the grades of GCT progression described by Campanacci. Serum of the 11 healthy subjects was available for comparison. The serum concentration of PINP was significantly higher in patients with GCT (82.4 +/- 46.2 ng/ml) than in controls (40.8 +/- 12.1 ng/ml) (P < 0.01), and that of ICTP was also significantly higher in GCT (5.3 +/- 2.0 ng/ml) than in controls (3.2 +/- 0.8 ng/ml) (P < 0.01). In GCT, the PINP concentration of grade 3 (127.6 +/- 38.8 ng/ml) was higher than that in grade 1 patients (46.9 +/- 4.8 ng/ ml) (P < 0.01). ICTP concentration of both grades 2 (7.1 +/- 1.4 ng/ml) and 3 (5.8 +/- 1.8 ng/ml) patients was significantly higher than that of grade 1 (3.5 +/- 0.6 ng/ ml) patients (P < 0.01, P < 0.05, respectively). Two cases of serum concentration of PINP and ICTP after resection of GCT demonstrated that these biomarkers decreased to the control levels in the absence of GCT. Our results indicated that type I collagen turnover evaluated by ICTP and PINP was stimulated in the presence of GCT. Moreover, this enhanced metabolic turnover reflects the grade of GCT.

Effects of high-intensity swimming training on GLUT-4 and glucose transport activity in rat skeletal muscle.

This study was performed to assess the effects of short-term, extremely high-intensity intermittent exercise training on the GLUT-4 content of rat skeletal muscle. Three- to four-week-old male Sprague-Dawley rats with an initial body weight ranging from 45 to 55 g were used for this study. These rats were randomly assigned to an 8-day period of high-intensity intermittent exercise training (HIT), relatively high-intensity intermittent prolonged exercise training (RHT), or low-intensity prolonged exercise training (LIT). Age-matched sedentary rats were used as a control. In the HIT group, the rats repeated fourteen 20-s swimming bouts with a weight equivalent to 14, 15, and 16% of body weight for the first 2, the next 4, and the last 2 days, respectively. Between exercise bouts, a 10-s pause was allowed. RHT consisted of five 17-min swimming bouts with a 3-min rest between bouts. During the first bout, the rat swam without weight, whereas during the following four bouts, the rat was attached to a weight equivalent to 4 and 5% of its body weight for the first 5 days and the following 3 days, respectively. Rats in the LIT group swam 6 h/day for 8 days in two 3-h bouts separated by 45 min of rest. In the first experiment, the HIT, LIT, and control rats were compared. GLUT-4 content in the epitrochlearis muscle in the HIT and LIT groups after training was significantly higher than that in the control rats by 83 and 91%, respectively. Furthermore, glucose transport activity, stimulated maximally by both insulin (2 mU/ml) (HIT: 48%, LIT: 75%) and contractions (25 10-s tetani) (HIT: 55%, LIT: 69%), was higher in the training groups than in the control rats. However, no significant differences in GLUT-4 content or in maximal glucose transport activity in response to both insulin and contractions were observed between the two training groups. The second experiment demonstrated that GLUT-4 content after HIT did not differ from that after RHT (66% higher in trained rats than in control). In conclusion, the present investigation demonstrated that 8 days of HIT lasting only 280 s elevated both GLUT-4 content and maximal glucose transport activity in rat skeletal muscle to a level similar to that attained after LIT, which has been considered a tool to increase GLUT-4 content maximally.

cDNA Cloning and mRNA analysis of PGC-1 in epitrochlearis muscle in swimming-exercised rats.

Peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1), a cold-inducible coactivator of nuclear receptors, stimulates mitochondrial biogenesis and respiration in muscle cells. In the present study, we first cloned a rat PGC-1 gene from a brown adipose tissue cDNA library which encodes a predicted 796-amino-acid protein and exhibits respectively 98% and 95% identity with the mouse and human homologues. Next, we examined the effect of swimming exercise training on the level of expression of the PGC-1 gene in rat epitrochlearis (Epi) muscle. PGC-1 mRNA level in Epi muscle in rats that swam 2 h a day for 3 and 7 days increased dramatically by 154% and 163%, respectively, compared to the non-exercised control group. PGC-1 mRNA up-regulation was not observed in an immersion group treated at 35 degrees C during the training program but without swimming exercise. These results demonstrate that expression of the PGC-1 gene in Epi muscle is induced not only by cold exposure but also by prolonged low-intensity physical exercise.

The importance of drug delivery systems in tissue engineering.

Tissue engineering is designed to regenerate natural tissues or to create biological substitutes for defective or lost tissues and organs through the use of cells. In addition to cells and their scaffolds, growth factors are required to promote tissue regeneration. Indeed, growth factor-induced vascularization is effective in supplying the oxygen and nutrients necessary for the survival of transplanted cells in organ substitution. However, growth factors have poor in vivo stability and so the biological effects are often unpredictable unless the delivery system is contrived. This review provides several examples to emphasize the importance of drug delivery systems in tissue engineering.

[Peak oxygen uptake, ventilatory threshold and leg extension power in apparently healthy Japanese].

Peak oxygen uptake, ventilatory threshold (VT) and leg extension power were measured in 832 apparently healthy subjects (421 males, 411 females) aged 30-60 decades who performed medical examination at 4 health check up facilities. 1) Peak oxygen uptake was greater in male than female, and decreased with age in both sexes. Single regression formula on age were Y (ml/kg/min) = 46.6 - 0.36 x AGE, (r = 0.447, p < 0.001) in male and Y (ml/kg/min) = 35.3 - 0.23 x AGE, (r = 0.407, p < 0.001) in female. 2) VT was greater in male than female, and less decreased with age compared to maximal aerobic power. Single regression formula on age were Y (ml/kg/min) = 22.6 - 0.13 x AGE, (r = 0.371, p < 0.001) in male, Y (ml/kg/min) = 20.0 - 0.10 x AGE, (r = 0.301, p < 0.001) in female. 3) Leg extension power was greater in male than female, and decreased with age in both sexes. Single regression formula on age were Y (W/kg) = 31.9 - 0.27 x AGE, (r = 0.539, p < 0.001) in male and Y (W/kg) = 20.9 - 0.18 x AGE, (r = 0.510, p < 0.001) in female. Subjects in the present study showed height, weight and walk steps per day similar to those in National Nutrition Survey. Comparison of Peak oxygen uptake, ventilatory threshold and leg extensor power to previous studies revealed that these parameters were quite similar to the counterparts in the previous studies with less selection bias. It was suggested that subjects in this study were quite similar to normal Japanese population, and that Peak oxygen uptake, VT and leg extension power in the present study were of value for the evaluation of health related fitness in community and workplace.

Effect of hand paddles on anaerobic energy release during supramaximal swimming.

PURPOSE: Swimmers swim faster using hand paddles. In this study the effect of maximal performance using hand paddles on aerobic and anaerobic energy release during supramaximal swimming was examined by comparing the maximal accumulated O2 deficit, and the aerobic and anaerobic energy release during exhaustive swimming with paddles (P) to swimming without paddles (hands only, H). METHODS: The subjects were six trained college male swimmers. Experiments were carried out in a swimming flume. The water flow rate was set before each exercise bout such that exhaustion occurred in 30 s, 1 min, or 2-3 min. Accumulated O2 deficit during exercise was determined by the accumulated oxygen demand minus the accumulated O2 uptake. RESULTS: Water flow rates at which maximal accumulated O2 deficit was obtained were significantly higher in P than that in H. However, mean values of maximal accumulated O2 deficit during H and P were 2.40+/-0.42 L and 2.32+/-0.37 L, respectively, and there was no significant difference between these two values. Furthermore, during the supramaximal swimming to exhaustion in 30 s, 1 min, or 2-3 min, both accumulated O2 uptake and accumulated O2 deficit did not significantly differ between these conditions, although mean water flow rates of these supramaximal swimming bouts were significantly higher in P than those in H again. CONCLUSIONS: These results suggest that the faster swimming speed accomplished with hand paddles does not affect metabolic responses and that it may be realized by recruitment of roughly the same muscle mass. Therefore, the ability to swim faster with hand paddles might mainly be attributed to other than metabolic factors, i.e., a higher propelling efficiency.

Resistance training affects GLUT-4 content in skeletal muscle of humans after 19 days of head-down bed rest.

This study assessed the effects of inactivity on GLUT-4 content of human skeletal muscle and evaluated resistance training as a countermeasure to inactivity-related changes in GLUT-4 content in skeletal muscle. Nine young men participated in the study. For 19 days, four control subjects remained in a -6 degrees head-down tilt at all times throughout bed rest, except for showering every other day. Five training group subjects also remained at bed rest, except during resistance training once in the morning. The resistance training consisted of 30 isometric maximal voluntary contractions for 3 s each; leg-press exercise was used to recruit the extensor muscles of the ankle, knee, and hip. Pauses (3 s) were allowed between bouts of maximal contraction. Muscle biopsy samples were obtained from the lateral aspect of vastus lateralis (VL) muscle before and after the bed rest. GLUT-4 content in VL muscle of the control group was significantly decreased after bed rest (473 +/- 48 vs. 398 +/- 66 counts. min-1. microgram membrane protein-1, before and after bed rest, respectively), whereas GLUT-4 significantly increased in the training group with bed rest (510 +/- 158 vs. 663 +/- 189 counts. min-1. microgram membrane protein-1, before and after bed rest, respectively). The present study demonstrated that GLUT-4 in VL muscle decreased by approximately 16% after 19 days of bed rest, and isometric resistance training during bed rest induced a 30% increase above the value of GLUT-4 before bed rest.