Cardiorespiratory fitness and physical activity in Luo,Kamba, and Maasai of rural Kenya

Background:

Although habitual physical activity energy expenditure (PAEE) and cardio‐respiratory fitness (CRF) are now well‐established determinants of metabolic disease, there is scarcity of such data from Africa. The aim of this study was to describe objectively measured PAEE and CRF in different ethnic populations of rural Kenya.

Methods:

A cross‐sectional study was done among 1,099 rural Luo, Kamba, and Maasai of Kenya. Participants were 17–68 years old and 60.9% were women. Individual heart rate (HR) response to a submaximal steptest was used to assess CRF (estimated VO₂max). Habitual PAEE was measured with combined accelerometry and HR monitoring, with individual calibration of HR using information from the step test.

Results:

Men had higher PAEE than women (～78 vs. ～67 kJ day^?1 kg^?1, respectively). CRF was similar in all three populations (～38 and ～43 mlO₂·kg^?1 min^?1 in women and men, respectively), while habitual PAEE measures were generally highest in the Maasai and Kamba. About 59% of time was spent sedentary (<1.5 METs), with Maasai women spending significantly less (55%). Both CRF and PAEE were lower in older compared to younger rural Kenyans, a difference which was most pronounced for PAEE in Maasai (?6.0 and ?11.9 kJ day^?1 kg^?1 per 10‐year age difference in women and men, respectively) and for CRF in Maasai men (?4.4 mlO₂·min^?1 kg^?1 per 10 years). Adjustment for hemoglobin did not materially change these associations.

Conclusion:

Physical activity levels among rural Kenyan adults are high, with highest levels observed in the Maasai and Kamba. The Kamba may be most resilient to age‐related declines in physical activity. Am. J. Hum. Biol. 2012. © 2012 Wiley Periodicals, Inc.

     

The influence of sexual maturation on blood pressure and body fatness in African‐American adolescent girls and boys

To examine the influence of sexual maturation (SM) on blood pressure (BP) and body fatness during puberty among African‐American children. Longitudinal data were collected from 283 African‐American children aged 9–15 years over a 1.5‐year period. Measured anthropometric measures included height, weight, skinfold thickness, waist circumference (WC), and systolic and diastolic BP (SBP/DBP) at baseline, 1‐year, and 1.5‐year follow‐up were used. SM was assessed using self‐reported Tanner stages (range 1–5) at baseline. Spearman correlation and regression analyses were conducted to test associations between study variables. Early maturing girls had higher BP and body mass index (BMI = weight (kg)/height (m)²) at follow‐up than nonearly maturing girls (SBP: 117.4 vs. 111.7; DBP: 66.3 vs. 60.7; BMI: 27.7 vs. 23.5; all P < 0.05, respectively). Baseline Tanner stage was positively associated with follow‐up SBP (r = 0.28), DBP (r = 0.37), BMI (r = 0.45), skinfold thickness (r = 0.37), and WC (r = 0.40) in girls, but not in boys. The influence of SM on BP independent of body size was tested via several different multiple linear regression models by adding measures of body size and their changes (height and BMI) between baseline and follow‐up. Early maturing girls had higher SBP and DBP (β = 4.30, P < 0.05; β = 3.28, P < 0.05; respectively) and BMI (β = 1.69, P < 0.05) at 1.5‐year follow‐up than their counterparts. In boys, a marginally significant reverse association (β = ?1.05 to ?1.19) between SM stages and DBP was detected. SM affects BP and body fatness in girls, and should be considered in assessment of BP and obesity in adolescents. Am. J. Hum. Biol., 2009. © 2008 Wiley‐Liss, Inc.     

Association between time spent in sedentary,moderate to vigorous physical activity,body mass index,cardiorespiratory fitness and blood pressure

Background: Elevated blood pressure (BP) has been reported in young people and seems to be associated with body mass index (BMI) and reduced physical activity (PA).

Aim: This study sought to analyse the association of BP with BMI, PA intensity patterns and cardiorespiratory fitness (CRF) in youth.

Subjects and methods: A cross-sectional study was carried out including 66 boys (13.91±1.76) and 97 girls (14.02±1.71). Anthropometric characteristics, CRF and BP were assessed during school time and accelerometers were utilized to determine intensity of PA.

Results: The linear regression model, adjusted for age, sex and height, showed that higher values of BMI were associated (p≤0.05) with higher values of systolic blood pressure (SBP) (1.39; 95% CI: 0.56; 2.23) and diastolic blood pressure (DBP) (1.52; 95% CI: 0.68; 2.37). Additionally, SBP, but not DBP, was inversely associated (p≤0.05) with moderate PA (?0.25; 95% CI: ?0.47; ?0.02) and positively correlated with sedentary activities (0.04; 95% CI: 0.00; 0.08).

Conclusion: The present study showed that BMI and time spent in sedentary activities were inversely associated with SBP. However, time spent in moderate PA was positively associated with SBP. BMI was the single predictor of DBP.     

Does erythrocyte infusion improve 3.2-km run performance at high altitude?

The purpose of this study was to determine whether there are differences in the effects of exercise training between those with a parental history of hypertension and those without such a history. A group of 39 middle-aged hypertensive women were submitted to a 4-month exercise training programme. On the basis of their family histories, 18 individuals were classified as those having a positive parental history of hypertension (group P) and 21 individuals as those without such a history (group N). Both groups participated in a supervised training programme with the intensity set at the level producing the threshold lactate concentration for 90–120?min twice a week, together with self-determined aerobic exercise three times a week. Vital age was estimated to determine the health-fitness status. At the end of the training, group N exhibited reductions in the systolic and diastolic blood pressures at rest (12.6/8.0?mmHg) and increases in the peak oxygen uptake [V˙O_2peak 21.1 (SD 5.2) vs 25.2 (SD 5.7) ml · kg^?1· min^?1] and oxygen uptake corresponding to lactate threshold [13.7 (SD 2.4) vs 17.0 (SD 2.0) ml?·?kg^?1?·?min^?1; P?P?V˙O_2peak (P?>?0.05). There were no changes in the blood lipid and haematocrit variables in either group. The vital age decreased by approximately 4 and 7?years (P?相似文献   

Genetic,environmental, and phenotypic links between body mass index and blood pressure among women

Greater relative weight is associated with higher blood pressure, but the reasons are unknown. The inability of current technology to induce sustained weight loss among overweight persons precludes experimental tests of whether this association is causal. We evaluated the degree to which the covariation between body mass index (BMI; kg/m²) and blood pressure (BP) among women is due to pleiotropic genetic factors, environmental factors, or phenotypic causation. The sample included 75 monozygotic (MZ) and 39 dizygotic (DZ) pairs of adult female twins. “BP” was calculated as the unitweighted mean of systolic and diastolic. Data were analyzed through structural equation modeling. A model was specified stipulating that additive genetic effects (A) and unique environmental effects (E) each contributed to the covariance between BMI and BP, thus allowing for both pleiotropic and unique environmental influences on the covariance between BMI and BP. Dropping the pleiotropic influences significantly worsened the model (χ² = 4.62, df = 1, P = .032), suggesting significant pleiotropic effects. Dropping the environmental influences on the cross-phenotype covariance did not significantly worsen the model (χ² = 1.42, df = 1, P =.233). This indicates no significant effect of the environment on the covariance between BMI and BP. Finally, a model of phenotypic causation in which BMI directly influenced BP was fitted. This model provided the best single parameter explanation of the BP-BMI covariation. These data suggest that, among women, regardless of the source of variation, chaanges in BMI should lead to long-standing changes in BP. © 1995 Wiley-Liss, Inc.     

Continuous measurement of blood pressure, heart rate and left ventricular performance during and after isometric exercise in head-out water immersion

Experiments were performed to determine the changes in blood pressure (BP), heart rate (HR) and left ventricular function during and after isometric knee extension during thermoneutral (35°C) head-out water immersion (HWI) or in air. Seven healthy male subjects mean age 24 (SD 3) years kept their knees extended (60% maximal voluntary extension) until they reached exhaustion. The mean BP at rest was 80 (SD 10) and 78 (SD 8) mmHg [10.7 (SD 1.33) and 10.4 (SD 1.07) kPa] in air and during HWI, respectively, (NS). They increased progressively (P < 0.01) during contraction and reached maximal values of 148 (SD 22) and 143 (SD 26) mmHg [19.7 (SD 2.93) and 19.1 (SD 3.47) kPa] in air and in HWI, respectively, (NS). The mean HR at rest was 74 (SD 8) and 70 (SD 11) beats·min^–1 in air and in HWI, respectively, (NS). They also increased progressively (P < 0.01) and reached 126 (SD 14) and 118 (SD 17) beats·min^–1 in air and in HWI, respectively, (NS). The changes in BP and HR during contraction in HWI tended to be smaller than those in air (NS). Left ventricular end diastolic diameters (dd) at rest in HWI were greater than those in air and were maintained at higher values during and after isometric contraction. In contrast, dd decreased during isometric contraction in air (P < 0.01). The change of left ventricular systolic diameters (d _s) in HWI was no different to those in air. From these findings, isometric exercise in thermoneutral HWI would seem to be characterized by a greater d _d than in air and this could be useful for patients with deconditioning effects such as orthostatic hypotension.     

Non‐invasive and quantitative evaluation of peripheral vascular resistances in rats by combined NMR measurements of perfusion and blood pressure using ASL and dynamic angiography

The in vivo determination of peripheral vascular resistances (VR) is crucial for the assessment of arteriolar function. It requires simultaneous determination of organ perfusion (F) and arterial blood pressure (BP). A fully non‐invasive method was developed to measure systolic and diastolic BP in the caudal artery of rats based on dynamic NMR angiography. A good agreement was found between the NMR approach and the gold standard techniques (linear regression slope = 0.98, R² = 0.96). This method and the ASL‐MRI measurement of skeletal muscle perfusion were combined into one single NMR experiment to quantitatively evaluate the local vascular resistances in the calf muscle of anaesthetized rats, in vivo and non‐invasively 1) at rest: VR = 7.0 ± 1.0 mmHg·min 100 g·ml^?1, F = 13 ± 3 ml min^?1.100 g^?1 and mean BP (MBP) = 88 ± 10 mmHg; 2) under vasodilator challenge (milrinone): VR = 3.7 ± 1.1 mmHg min.100 g ml^?1, F = 21 ± 4 ml min^?1.100 g^?1 and MBP = 75 ± 14 mmHg; 3) under vasopressor challenge (norepinephrine): VR = 9.8 ± 1.2 mmHg min 100 g ml^?1, F = 14 ± 3 ml min^?1.100 g^?1 and MBP = 137 ± 2 mmHg. Copyright © 2009 John Wiley & Sons, Ltd.     

Effects of physical inactivity on aortic distensibility in visually impaired young men

To assess the effects of inordinate physical inactivity on the distensibility of the aorta we measured aortic pulse wave velocity (APWV) and estimated physical activity index (PAI) by a 7-day total activity recall in visually impaired subjects. A group of 12 blind students (blind group) and 28 sighted male students, including 14 runners (runner group) and 14 sedentary subjects (sedentary group), participated in this study. There were no significant differences in body height, body mass, or blood pressure among the three groups. The PAI of the blind group [310 (SD 330) kcal · week^?1] was significantly lower than that of the runner group [6300 (SD 1920) kcal?·?week^?1; P??1; P?P??1 and 5.54 (SD 0.57) m?·?s^?1; P??1 and 6.16 (SD 0.48) m?·?s^?1]. The APWV and APWVI of the blind group [5.29 (SD 0.49) m?·?s^?1 and 5.40 (SD 0.60) m?·?s^?1; P?相似文献   

Energy and substrate metabolism during a 42-day bed-rest in a head-down tilt position in humans

Microgravity-induced changes in body composition (decrease in muscle mass and increase in fat mass) and energy metabolism were studied in seven healthy male subjects during a 42-day bed-rest in a head-down tilt (HDT) position. Resting energy expenditure (REE), fat and glucose oxidation were estimated by indirect calorimetry on days 0, +8 and +40 of the HDT period. Assessments were performed both in post-absorptive conditions and following two identical test meals given at 3-h intervals. Body composition (dual x-ray absorptiometry) was measured on days 0, +27, +42. Mean post-absorptive lipid oxidation decreased from 53 (SEM 8) mg?·?min^?1 (day 0) to 32 (SEM 10) mg?·?min^?1 (day 8, P=0.04) and 36 (SEM 8) mg?·?min^?1 (day 40, P=0.06). Mean post-absorptive glucose oxidation rose from 126 (SEM 15) mg?·?min^?1 (day 0) to 164 (SEM 14) mg?·?min^?1 (day 8, P=0.04) and 160 (SEM 20) mg?·?min^?1 (day 40, P=0.07). Mean fat-free mass (FFM) decreased between days 0 and 42 [58.0 (SEM 1.8) kg and 55.3 (SEM 1.7) kg, P<0.01] while fat mass increased without reaching statistical significance. The mean REE decreased from 1688 (SEM 50) kcal?·?day^?1 to 1589 (SEM 42) kcal?·?day^?1 (P=0.056). Changes in REE were accounted for by changes in FFM. Mean energy intake decreased from 2532 (SEM 43) kcal?· day^?1 to 2237 (SEM 50) kcal?·?day^?1 (day 40, P<0.01) with only a minor decrease in the proportion of fat. We concluded that changes in fat oxidation at the whole body level can be found during HDT experiments. These changes were related to the decrease in FFM and could have promoted positive fat balance hence an increase in fat mass.     

The effect of gender on left ventricular function immediately after the wingate test

The effect of gender on left ventricular systolic function and exercise haemodynamics in healthy young subjects was studied during 30-s all-out sudden strenuous dynamic exercise. A group of 22 men [19.3 (SD 1) years] 20 women [19.1 (SD 1) years] volunteered to participate in this study. Two-dimensional direct M-mode and Doppler echocardiograph studies were performed with the subject in the sitting position. The Doppler examination of flow was located with continuous-wave, interrogating ascending aorta measurements. The subjects completed the study without showing any electrocardiograph abnormalities. An interaction effect with stroke volume (P?P??1) for the men and 12.1 (SD 4) l?·?min^?1 for the women compared to the rest values [5.8 (SD 0.4) and 4.7 (SD 0.5) l?·?min^?1, respectively]. Flow velocity integral and acceleration time differed significantly between the two groups at rest (P?P?P?相似文献   

Arterial blood pressure and forearm vascular conductance responses to sustained and rhythmic isometric exercise and arterial occlusion in trained rock climbers and untrained sedentary subjects

Cardiovascular responses to sustained and rhythmic (5?s on, 2?s off?) forearm isometric exercise to fatigue at 40% maximal voluntary contraction (MVC) and to a period of arterial occlusion were investigated in elite rock climbers (CLIMB) as a trained population compared to non-climbing sedentary subjects (SED). Blood pressure (BP), monitored continuously by Finapres, and forearm blood flow, by venous occlusion plethysmography, were measured and used to calculate vascular conductance. During sustained exercise, times to fatigue were not different between CLIMB and SED. However, peak increases in systolic (S) BP were significantly lower in CLIMB [25 (13)?mmHg; (3.3 (1.7)?kPa] than in SED [48 (17)?mmHg; (6.4 (2.3)?kPa] (P<0.05), with a similar trend for increases in diastolic (D) BP. Immediately after sustained exercise, forearm conductance was higher in CLIMB than SED (P<0.05) for up to 2?min. During rhythmic exercise, times to fatigue were two fold longer in CLIMB than SED [853 (76) vs 420 (69)?s, P<0.05]. Increases in SBP were not different between groups except during the last quarter of exercise when they fell in CLIMB. Conductance both during and after rhythmic exercise was higher in CLIMB than in SED. Following a 10-min arterial occlusion, peak vascular conductance was significantly greater in CLIMB than SED [0.597 (0.084) vs 0.431 (0.035)?ml · min^?1?· 100?ml^?1?·?mmHg^?1; P<0.05]. The attenuated BP response to sustained isometric exercise could be due in part to enhanced forearm vasodilatory capacity, which also supports greater endurance during rhythmic exercise by permitting greater functional hyperaemia in between contraction phases. Such adaptations would all facilitate the ability of rock climbers to perform their task of making repetitive sustained contractions.     

Left ventricular pressure–volume relationships during normal growth and development in the adult rat – studies in 8‐ and 50‐week‐old male Wistar rats

Aims: Left ventricular (LV) pressure–volume relations provide relatively load‐independent indexes of systolic and diastolic LV function, but few data are available on pressure–volume relations during growth and development in the normal adult heart. Furthermore, to quantify intrinsic ventricular function the indexes should be normalized for heart weight. However, in many studies the indexes are reported in absolute terms, or body weight‐correction is used as a surrogate for heart weight‐correction. Methods: We determined pressure–volume relations in young (8‐week‐old, n = 13) and middle‐aged (50‐week‐old, n = 19) male Wistar rats in relation to their heart and body weights. The animals were anaesthetized and a 2F pressure‐conductance catheter was introduced into the LV to measure pressure–volume relations. Results: Heart and body weights were significantly higher in the 50‐week‐old rats, whereas the heart‐to‐body weight ratio was significantly lower (2.74 ± 0.32 vs. 4.41 ± 0.37 mg g^?1, P < 0.001). Intrinsic systolic function, quantified by the slopes of the end‐systolic pressure–volume relation (E_ES), the dP/dt_MAX vs. end‐diastolic volume relation (S‐dP), and the preload recruitable stroke work relation (PRSW), normalized for heart weight, was slightly decreased in the 50‐week‐old rats (S‐dP: ?6%, P < 0.004; PRSW: ?3%, P < 0.06). Heart weight‐corrected diastolic indexes were not significant different. The absolute indexes qualitatively showed the same results, but body‐weight corrected pressure–volume indexes showed improved systolic function and significantly depressed diastolic function. Conclusions: Intrinsic systolic function slightly decreases from the juvenile to the middle‐aged period in normal male Wistar rats. Furthermore, correction of pressure–volume indexes for body weight is not an adequate surrogate for heart weight‐correction in these animals.     

The effects of asymmetric ventricular filling on left–right ventricular interaction in the normal rat heart

Heart failure is characterised by ventricular dysfunction and with the potential for changes to ventricular volumes constraining the mechanical performance of the heart. The contribution of this interaction from geometric changes rather than fibrosis or metabolic changes is unclear. Using the constant pressure Langendorff-perfused rat heart, the volume interaction between left ventricle (LV) and right ventricle (RV) was investigated. RV diastolic stiffness (P?<?0.001) and developed pressure (P?<?0.001) were significantly lower than LV. When the RV was fixed at the end-diastolic volume (EDV) or EDV?+?50?%, both LV systolic and diastolic performance were unaffected with increasing LV balloon volume. However, at fixed LV volume, RV systolic performance was significantly decreased when LV volume increased to EDV?+?50?% when RV volume was increased incrementally between 50 and 300?μl (P?<?0.001). Systolic interaction in RV was noted as declining RV peak systolic load with increasing LV systolic pressure (P?<?0.05) and diastolic interaction was noted for RV when LV volume was increased from EDV to EDV?+?50?% (P?<?0.05). RV diastolic wall stress was increased with increasing LV balloon volume (P?<?0.05), but LV wall stress was unaltered at fixed RV balloon volume. Taken together, increasing LV volume above EDV decreased systolic performance and triggered ventricular constraint in the RV but the RV itself had no effect on the performance of the LV. These results are consistent with overload of the LV impairing pulmonary perfusion by direct ventricular interaction with potential alteration to ventilation–perfusion characteristics within the lung.     

Energy expenditure and intensity of ritual jumping–dancing in male Maasai

Objectives

Traditional jumping–dance rituals performed by Maasai men involve prolonged physical exertion that may contribute significantly to overall physical activity level. We aimed to objectively quantify the metabolic intensity of jumping–dance activity and assess associations with habitual physical activity and cardiorespiratory fitness (CRF).

Methods

Twenty Maasai men (18–37 years) from rural Tanzania volunteered to participate in the study. Habitual physical activity was monitored using combined heart rate (HR) and movement sensing over 3 days, and jumping–dance engagement was self-reported. A 1-h jumping–dance session resembling a traditional ritual was organized, during which participants' vertical acceleration and HR were monitored. An incremental, submaximal 8-min step test was performed to calibrate HR to physical activity energy expenditure (PAEE) and assess CRF.

Results

Mean (range) habitual PAEE was 60 (37–116) kJ day⁻¹ kg⁻¹, and CRF was 43 (32–54) mL O₂ min⁻¹ kg⁻¹. The jumping–dance activity was performed at an absolute HR of 122 (83–169) beats·min⁻¹, and PAEE of 283 (84–484) J min⁻¹ kg⁻¹ or 42 (18–75)% when expressed relative to CRF. The total PAEE for the session was 17 (range 5–29) kJ kg⁻¹, ~28% of the daily total. Self-reported engagement in habitual jumping–dance frequency was 3.8 (1–7) sessions/week, with a total duration of 2.1 (0.5–6.0) h/session.

Conclusions

Intensity during traditional jumping–dance activity was moderate, but on average sevenfold higher than habitual physical activity. These rituals are common, and can make a substantial contribution to overall physical activity in Maasai men, and thus be promoted as a culture-specific activity to increase energy expenditure and maintain good health in this population.     

A synthetic hydroxypropenone inhibits nitric oxide,prostaglandin E2, and proinflammatory cytokine synthesis

HMP [3-(2-hydroxyphenyl)-1-(5-methyl-furan-2-y-l) propenone] was evaluated for its ability to inhibit the synthesis of major proinflammatory mediators and cytokines in interferon-γ (IFN-γ)- and lipopolysaccharide (LPS)-induced RAW 264.7 cells and phorbol myristate acetate (PMA)-differentiated/LPS-induced U937 cells. HMP suppressed the production of nitric oxide (NO) with significant inhibitory effects at doses as low as 0.78?μM (P?<?0.05). Prostaglandin E2 (PGE2) secretion was also inhibited at doses of 12.5?μM and above (P?<?0.01). The secretion of both TNF-α and IL-6 were only inhibited at the highest dose used (25?μM; P?<?0.001). IL-1β secretion was also inhibited from 12.5?μM onwards (P?<?0.01). This inhibition was demonstrated to be caused by down-regulation of inducible enzymes, inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2), without direct effect upon iNOS or COX-2 enzyme activity. HMP only inhibited iNOS (P?<?0.001) and IL-1β (P?<?0.05) gene expression at the highest tested concentration. HMP did not affect the secretion of chemokines IL-8 and monocyte chemotactic protein-1 (MCP-1) and the anti-inflammatory cytokine IL-10. The most striking effect of HMP was its NO inhibitory activity and therefore we conclude that HMP is a selective inhibitor of iNOS.     

Flow cytometric analysis of TCR Vβ repertoire in patients with 22q11.2 deletion syndrome

In 22q11.2 deletion patients, the normal decrease in T lymphocyte counts after 1–2 years is blunted such that relatively T lymphocyte numbers increase over early childhood, probably via post‐thymic expansion of peripheral lymphocytes. This may leave less T lymphocyte receptor (TCR) diversity than when derived from naive thymic emigrants. We analysed TCR Vβ repertoire on 27 22q11.2 chromosome deletion patients. No patient had infection at sampling. CD3⁺CD4⁺ recent thymic emigrants (RTEs) were identified by CD45RA and CD31 expression. TCR Vβ repertoire was determined using four‐colour flow cytometry. Patients and controls showed significant TCR Vβ family usage differences between CD3⁺CD4⁺ and CD3⁺CD4^? T lymphocyte subpopulations. Vβ family abnormalities (±3 SD of controls) were identified in 18/27 (67%) patients and 12/47 (25%) controls. In patients, the magnitude of expansions was increased, with some Vβ families representing 37% of the cells present in the subpopulations. There was a significant increase in frequency of abnormalities in CD3⁺CD4⁺ (P < 0.001) and CD3⁺CD4^? T lymphocytes (P < 0.05) in patients. A total of 11/16 patients had an abnormal CD4⁺CD25^Bright TCR Vβ repertoire. There was no difference in expansions/contractions between CD4⁺CD25^Bright and CD4⁺ T lymphocyte repertoires (P = 0.575) for individual patients but significant differences in expansions/contractions between CD4⁺CD25^Bright and CD8⁺ T lymphocytes repertoires (P = 0.011). There was bias in Vβ usage between CD3⁺CD4⁺ and CD3⁺CD4^? T lymphocyte subsets. A total of 67% patients had TCR Vβ repertoire abnormalities, with a trend towards increased repertoire abnormalities with fewer RTEs, suggesting thymic output plays an important role in TCR repertoire diversity. There was no correlation between skewed repertoire and symptoms of infection or autoimmunity.     

Glucagon-like peptide-1 reduces hepatic glucose production indirectly through insulin and glucagon in humans

The effect of glucagon-like peptide-1 (GLP-1) on hepatic glucose production and peripheral glucose utilization was investigated with or without infusion of somatostatin to inhibit insulin and glucagon secretion in 13 healthy, non-diabetic women aged 59 years. After 120 min 3-³H-glucose infusion, GLP-1 was added (4.5 pmol kg^?1 bolus + 1.5 pmol kg^?1 min^?1). Without somatostatin (n = 6), GLP-1 decreased plasma glucose (from 4.8 ± 0.2 to 4.2 ± 0.3 mmol L^?1, P = 0.007). Insulin levels were increased (48 ± 3 vs. 243 ± 67 pmol L^?1, P = 0.032), as was the insulin to glucagon ratio (P = 0.044). The rate of glucose appearance (R_a) was decreased (P = 0.003) and the metabolic clearance rate of glucose (MCR) was increased during the GLP-1 infusion (P = 0.024 vs. saline). Also, the rate of glucose disappearance (R_d) was reduced during the GLP-1 infusion (P = 0.004). Since R_a was reduced more than R_d, the net glucose flow was negative, which reduced plasma glucose. Somatostatin infusion (500 μg h^?1, n = 7) abolished the effects of GLP-1 on plasma glucose, serum insulin, insulin to glucagon ratio, R_a, R_d, MCR and net glucose flow. The results suggest that GLP-1 reduces plasma glucose levels mainly by reducing hepatic glucose production and increasing the metabolic clearance rate of glucose through indirectly increasing the insulin to glucagon ratio in healthy subjects.     

Genetic and environmental influences on blood pressure and physical activity: a study of nuclear families from Muzambinho,Brazil

Blood pressure (BP) and physical activity (PA) levels are inversely associated. Since genetic factors account for the observed variation in each of these traits, it is possible that part of their association may be related to common genetic and/or environmental influences. Thus, this study was designed to estimate the genetic and environmental correlations of BP and PA phenotypes in nuclear families from Muzambinho, Brazil. Families including 236 offspring (6 to 24 years) and their 82 fathers and 122 mothers (24 to 65 years) were evaluated. BP was measured, and total PA (TPA) was assessed by an interview (commuting, occupational, leisure time, and school time PA). Quantitative genetic modeling was used to estimate maximal heritability (h²), and genetic and environmental correlations. Heritability was significant for all phenotypes (systolic BP: h² = 0.37 ± 0.10, P < 0.05; diastolic BP: h² = 0.39 ± 0.09, P < 0.05; TPA: h² = 0.24 ± 0.09, P < 0.05). Significant genetic (r_g) and environmental (r_e) correlations were detected between systolic and diastolic BP (r_g = 0.67 ± 0.12 and r_e = 0.48 ± 0.08, P < 0.05). Genetic correlations between BP and TPA were not significant, while a tendency to an environmental cross-trait correlation was found between diastolic BP and TPA (r_e = -0.18 ± 0.09, P = 0.057). In conclusion, BP and PA are under genetic influences. Systolic and diastolic BP share common genes and environmental influences. Diastolic BP and TPA are probably under similar environmental influences.     

Haemodynamic response to exercise in healthy young and elderly subjects

Whereas with advancing age, peak heart rate (HR) and cardiac index (CI) are clearly reduced, peak stroke index (SI) may decrease, remain constant or even increase. The aim of this study was to describe the patterns of HR, SI, CI, arteriovenous difference in oxygen concentration (C _a-vO₂), mean arterial pressure (MAP), systemic vascular resistance index (SVRI), stroke work index (SWI) and mean systolic ejection rate index (MSERI) in two age groups (A: 20–30 years, n = 20; B: 50–60 years n = 20. After determination of pulmonary function, an incremental bicycle exercise test was performed, with standard gas-exchange measurements and SI assessment using electrical impedance cardiography. The following age-related changes were found: similar submaximal HR response to exercise in both groups and a higher peak HR in A than in B[185 (SD 9) vs 167 (SD 14) beats?·?min^?1, P??2, P??1?·?m^?2, P?C _a-vO₂ during exercise; higher MAP at all levels of exercise in B; higher SVRI at all levels of exercise in B; lower SWI in B after recovery; higher MSERI at all levels of exercise in A. The decrease in SI with advancing age would seem to be related to a decrease in myocardial contractility, which can no longer be compensated for by an increase in preload (as during submaximal exercise). Increases in systemic blood pressure may also compromise ventricular function but would seem to be of minor importance.