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Biomedical subjects

M World

Publications and source records attributed to M World.

8 recordsLinked to original sources
PubMed2002

Endurance enhancement related to the human angiotensin I-converting enzyme I-D polymorphism is not due to differences in the cardiorespiratory response to training.

Human physical performance is strongly influenced by genetic factors. We have previously reported that the I variant of the human angiotensin I-converting enzyme (ACE) gene is associated with greater endurance performance in mountaineers and Olympic runners and improved performance in army recruits. In this study we examined whether this effect is mediated by improvements in cardiovascular fitness with training in 58 army recruits homozygous for the insertion (I, ACE genotype II) or deletion (D, ACE genotype DD) allele. A submaximal and maximal exercise protocol was used to calculate both the heart rate/oxygen uptake (VO2) relationship and changes in maximal oxygen uptake (VO2max), respectively. There was no significant intergroup difference in VO2max at baseline (P=0.19) or after training (P=0.22). There was no difference between genotypes with training in the heart rate/VO2 elevation (P = 0.79 for the mean difference in mean adjusted heart rates). However, VO2 at all exercise intensities in the submaximal test was lower for all subjects after training and at 80 W the reduction in VO2 was greater for the II subjects compared to DD subjects [mean(SEM)] [1.6 (0.27) and 0.68 (0.27) ml kg(-1) min(-1), respectively; P = 0.02 for mean difference]. The I/D polymorphism may play a role in enhanced endurance performance but this is not mediated by differences in VO2max or the heart rate/VO2 relationship in response to training.

Exercise↗
PubMed2001

Bradykinin B2BKR receptor polymorphism and left-ventricular growth response.

Angiotensin-converting-enzyme (ACE) activity regulates left-ventricular growth. The deletion (D), rather than the insertion (I), ACE gene variant is associated with increased ACE activity and kinin degradation, and the absence (-) rather than the presence (+) of a 9 bp deletion in the gene encoding the bradykinin 2 receptor (B2BKR) is associated with greater gene expression. We determined the ACE and B2BKR genotype of 109 male army recruits, and measured their physiological left-ventricular growth response to a 10-week physical training programme. Mean left-ventricular growth was 15.7 g (SE 3.5) in those with ACE genotype D/D and B2BKR genotype +9/+9, but -1.37 g (4.1) in those with ACE genotype I/I and B2BKR genotype -9/-9 (p=0.003 for trend across genotypes). These results suggest that kinins regulate left-ventricular growth, mediating some of the effects of ACE in this regard.

Adult↗
PubMed1999

Angiotensin-converting-enzyme gene insertion/deletion polymorphism and response to physical training.

BACKGROUND: The function of local renin-angiotensin systems in skeletal muscle and adipose tissue remains largely unknown. A polymorphism of the human angiotensin converting enzyme (ACE) gene has been identified in which the insertion (I) rather than deletion (D) allele is associated with lower ACE activity in body tissues and increased response to some aspects of physical training. We studied the association between the ACE gene insertion or deletion polymorphism and changes in body composition related to an intensive exercise programme, to investigate the metabolic effects of local human renin-angiotensin systems. METHODS: We used three independent methods (bioimpedance, multiple skinfold-thickness assessment of whole-body composition, magnetic resonance imaging of the mid-thigh) to study changes in body composition in young male army recruits over 10 weeks of intensive physical training. FINDINGS: Participants with the II genotype had a greater anabolic response than those with one or more D alleles for fat mass (0.55 vs -0.20 kg, p=0.04 by bioimpedance) and non-fat mass (1.31 vs -0.15 kg, p=0.01 by bioimpedance). Changes in body morphology with training measured by the other methods were also dependent on genotype. INTERPRETATION: II genotype, as a marker of low ACE activity in body tissues, may conserve a positive energy balance during rigorous training, which suggests enhanced metabolic efficiency. This finding may explain some of the survival and functional benefits of therapy with ACE inhibitors.

Adipose Tissue↗
PubMed1999

Exercise training enhances endothelial function in young men.

OBJECTIVES: The present study was designed to assess whether exercise training can enhance endothelium-dependent dilatation in healthy young men. BACKGROUND: Exercise has been shown to reduce cardiovascular morbidity and mortality, but the mechanisms for this benefit are unclear. Endothelial dysfunction is an early event in atherogenesis, and animal studies have shown that exercise training can enhance endothelial function. METHODS: We have examined the effect of a standardized, 10-week, aerobic and anaerobic exercise training program on arterial physiology in 25 healthy male military recruits, aged 17 to 24 (mean 20) years, of average fitness levels. Each subject was studied before starting, and after completing the exercise program. Baseline vascular reactivity was compared with that of 20 matched civilian controls. At each visit, the diameter of the right brachial artery was measured at rest, during reactive hyperemia (increased flow causing endothelium-dependent dilation) and after sublingual glyceryltrinitrate (GTN; an endothelium-independent dilator), using high-resolution external vascular ultrasound. RESULTS: At baseline, flow-mediated dilatation (FMD) and GTN-mediated dilatation were similar in the exercise and control groups (FMD 2.2+/-2.4% and 2.4+/-2.8%, respectively, p = 0.33; GTN 13.4+/-6.2 vs. 16.7+/-5.9, respectively, p = 0.53). In the military recruits, FMD improved from 2.2+/-2.4% to 3.9+/-2.5% (p = 0.01), with no change in the GTN-mediated dilation (13.4+/-6.2% vs. 13.9+/-5.8%, p = 0.31) following the exercise program. CONCLUSION: Exercise training enhances endothelium-dependent dilation in young men of average fitness. This may contribute to the benefit of regular exercise in preventing cardiovascular disease.

Administration, Sublingual↗
PubMed1997

Association of angiotensin-converting enzyme gene I/D polymorphism with change in left ventricular mass in response to physical training.

BACKGROUND: The absence (deletion allele [D]) of a 287-base pair marker in the ACE gene is associated with higher ACE levels than its presence (insertion allele [I]). If renin-angiotensin systems regulate left ventricular (LV) growth, then individuals of DD genotype might show a greater hypertrophic response than those of II genotype. We tested this hypothesis by studying exercise-induced LV hypertrophy. METHODS AND RESULTS: Echocardiographically determined LV dimensions and mass (n=140), electrocardiographically determined LV mass and frequency of LV hypertrophy (LVH) (n=121), and plasma brain natriuretic peptide (BNP) levels (n=49) were compared at the start and end of a 10-week physical training period in male Caucasian military recruits. Septal and posterior wall thicknesses increased with training, and LV mass increased by 18% (all P<.0001). Response magnitude was strongly associated with ACE genotype: mean LV mass altered by +2.0, +38.5, and +42.3 g in II, ID and DD, respectively (P<.0001). The prevalence of electrocardiographically defined LVH rose significantly only among those of DD genotype (from 6 of 24 before training to 11 of 24 after training, P<.01). Plasma brain natriuretic peptide levels rose by 56.0 and 11.5 pg/mL for DD and II, respectively (P<.001). CONCLUSIONS: Exercise-induced LV growth in young males is strongly associated with the ACE I/D polymorphism.

Adult↗
PubMed1996

The acute rise in plasma fibrinogen concentration with exercise is influenced by the G-453-A polymorphism of the beta-fibrinogen gene.

We have investigated the effects of chronic physical training and acute intensive exercise on plasma fibrinogen levels and the relationship of these responses to beta-fibrinogen G-453-A polymorphism genotype. One hundred fifty-six male British Army recruits were studied at the start of their 10-week basic training, which emphasizes physical fitness. Cohorts were restudied between 0.5 and 5 days after a major 2-day strenuous military exercise (ME) undertaken in their final week of training. Changes in fibrinogen concentration were adjusted for the effects of age, body mass index, and smoking history. Compared with baseline values, fibrinogen concentrations were significantly lower (11.9%, P=.04) at day 5 after ME, consistent with the beneficial effect of training. However, they were higher on days 1 through 3 after ME (suggesting an "acute-phase" response to strenuous exercise) and were maximal on days 1 and 2 (27.2%, P<.001 and 37.1%, P<.001 respectively). Fibrinogen genotype was available in 149 individuals. As expected from previous studies, men with one or more fibrinogen gene A-453 alleles had plasma fibrinogen concentration slightly but significantly higher at baseline (4.5%, P=.11). During the acute-phase response (days 2 and 3), however, the degree of rise was strongly related to the presence of the A allele, being 26.7+/-5.4% (mean+/-SE), 36.5+/-11.0%, and 89.2+/-30.7 for the GG, GA, and AA genotypes, respectively (P=.01). These results confirm that chronic exercise training lowers plasma fibrinogen levels, that intensive exercise generates an acute-phase rise in levels, and that this acute response is strongly influenced by the G/A polymorphism of the beta-fibrinogen gene.

Adolescent↗