Human gene for physical performance

Genetic variation in the renin-angiotensin system and response to endurance training

OBJECTIVE

To investigate the relationship between genetic variation in the renin-angiotensin system and the effect of 12-week endurance training in Korean women.

MATERIALS AND METHODS

Seventeen women who participated in an endurance training program for 12 weeks were genotyped for the angiotensinogen M235T polymorphism, angiotensin II type 1 receptor A1166C polymorphism, angiotensin-converting enzyme (ACE) T-3892C polymorphism, and angiotensin II type 2 receptor C3123A polymorphism. The following clinical parameters were measured before and after the endurance training program: blood pressure, body composition, ventilatory response, total cholesterol, triglyceride, and glucose.

RESULTS

Of the genetic markers investigated, the frequency of the T allele for the ACE T-3892C polymorphism was significantly associated with the response in body mass index and VO(2max) after 12 weeks of endurance training (p< 0.05). None of the other polymorphisms were significantly associated with the effect of training.

CONCLUSION

The significant association between ACE T-3892C and the change in body mass index and VO(2max) in Korean women are attributed to training, suggesting that this genetic variation is a useful genetic marker for clarifying the interindividual response to endurance training.

Variation in ACE activity affects myogenic differentiation in C2C12 cells

Variation in ACE activity is related to affect the skeletal muscle function. To elucidate the mechanism by which ACE affects skeletal muscle function, we examined the effects of loss and gain of ACE activity on myogenic differentiation in C2C12 myoblasts. The treatment of captopril, an ACE inhibitor, in differentiating cells significantly induced the up-regulation of myosin heavy chain, and the hypertrophic myotubes. In addition, an AT2 antagonist PD123319, not AT1 antagonist losartan, induced the up-regulation of myosin heavy chain. On the other hand, overexpression of ACE induced the down-regulation of myosin heavy chain. These results suggest that ACE negatively regulate the myogenesis through the mechanism at least in part via production of angiotensin II followed by its binding to AT2 receptor.

No contribution of angiotensin-converting enzyme (ACE) gene variants to severe obesity: a model for comprehensive case/control and quantitative cladistic analysis of ACE in human diseases

Candidate gene analyses are often inconclusive owing to genetic or phenotypic heterogeneity, low statistical power, selection of nonfunctional SNPs, and inadequate statistical analysis of the genetic architecture. Angiotensin-converting enzyme (ACE) is involved in adipocyte growth and function and the ACE-processed angiotensin II inhibits adipocyte differentiation. Associations between body mass index (BMI) and ACE polymorphisms have been reported in general populations, but the contribution to severe obesity of this gene, which is located under an obesity genome-scan linkage peak on 17q23, is unknown. ACE is one of the most studied genes and markers responsible for variation in circulating ACE enzyme levels have been extensively characterised. Eight of these variants were genotyped in 1054 severely obese cases and 918 nonobese controls, as well as 116 nuclear families from the genome scan (n=447), enabling the known clades to be inferred. Qualitative analysis of individual single-nucleotide polymorphisms (SNPs), haplotypes, clades, and diploclades demonstrated no significant associations (P<0.05) after minimal correction for multiple testing. Quantitative analysis of clades and diploclades for BMI, waist-to-hip ratio, or ZBMI in children were also not significant. This rigorous, large-scale study of common, well-defined, severe polygenic obesity provides strong evidence that functionally relevant sequence variation in ACE, whether it is defined at the level of SNPs, haplotypes, or clades, is not associated with severe obesity in French Caucasians. Such a study design exemplifies the strategy needed to clearly define the contribution of the ACE gene to the plethora of complex genetic diseases where weak associations have been previously reported.

Evidence for a genetic basis for altitude-related illness

Altitude-related illnesses are a family of interrelated pulmonary, cerebral, hematological, and cardiovascular medical conditions associated with the diminished oxygen availability at moderate to high altitudes. The acute forms of these debilitating and potentially fatal conditions, which include acute mountain sickness (AMS), high altitude pulmonary edema (HAPE), and high altitude cerebral edema (HACE), often develop in incompletely acclimatized lowlanders shortly after ascent, whereas, the chronic conditions, such as chronic mountain sickness (CMS) and high altitude pulmonary hypertension (HAPH), usually afflict native or long-term highlanders and may reflect a loss of adaptation. Anecdotal reports of particularly susceptible people or families are frequently cited as evidence that certain individuals have an innate susceptibility (or resistance) to developing these conditions and, in recent decades, there have been a number of studies designed to characterize the physiology of individuals predisposed to these conditions, as well as to identify the specific genetic variants that contribute to this predisposition. This paper reviews the epidemiological evidence for a genetic component to the various forms of altitude-related illness, such as innate susceptibility, familial clustering, and patterns of population susceptibility, as well as the molecular evidence for specific genetic risk factors. While the evidence supports some role for genetic background in the etiology of altitude-related illness, limitations in individual studies and a general lack of corroborating research limit the conclusions that can be drawn about the extent of this contribution and the specific genes or pathways involved. The paper closes with suggestions for future work that could support and expand on previous studies, as well as provide new insights.

No Association Between Variants in the ACE and Angiotensin II Receptor 1 Genes and Acute Mountain Sickness in Nepalese Pilgrims to the Janai Purnima Festival at 4380 m

Koehle, Michael S., Pei Wang, Jordan A. Guenette, and Jim L. Rupert. No association between variants in the ACE and angiotensin II receptor 1 genes and acute mountain sickness in Nepalese pilgrims to the Janai Purnima Festival at 4380 m. High Alt. Med. Biol. 7:281-289, 2006.--Acute mountain sickness (AMS) causes significant morbidity among visitors to altitude. The primary contributors to developing AMS are altitude and rate of ascent; however, the substantial variation in susceptibility between individuals has led a number of investigators to propose that there may be genetic predilection to the disease. The ACE I/D polymorphism has been shown to predict performance among elite mountaineers. This study compares genotype and allele frequencies at the ACE I/D locus, two other loci in the ACE gene, and one locus in the angiotensin-2 receptor gene between individuals who did, or did not, express signs of AMS while attending a high altitude religious festival in Nepal (4380 m). Subjects (80 males, 23 females) were recruited and genotyped. All subjects were Nepalese. Forty-four of the subjects had been diagnosed with AMS by physicians at a high altitude health camp; the rest were free from altitude illness. All subjects were genotyped at polymorphic loci in the genes encoding angiotensin converting enzyme (ACE) and angiotensin II receptor type 1 gene (AGTR1). The polymorphisms examined were two single nucleotide polymorphisms (SNPs) in ACE (ACE(A-240T), dbSNP rs4291; and ACE(A2350G), dbSNP rs4343), the intronic Alu insertion in ACE (ACE I/D), and the SNP ATR(A1166C), (dbSNP rs17231380) in AGTR1d. All polymorphisms in ACE were found to be in linkage disequilibrium. No significant associations were found between AMS incidence and any of the alleles, suggesting that variants at these loci do not contribute to susceptibility to AMS in this population.

Rethinking Enhancement in Sport

This article explores the arguments surrounding the use of human enhancement technologies in sport, arguing for a reconceptualization of the doping debate. First, it develops an overview and critique of the legislative structures on enhancement. Subsequently, a conceptual framework for understanding the role of technological effects in sport is advanced. Finally, two case studies (hypoxic chambers and gene transfer) receive specific attention, through which it is argued that human enhancement technologies can enrich the practice of elite sports rather than diminish them. In conclusion, it is argued that elite sports are at a pivotal moment in their history as an increasing range of enhancements makes less relevant the protection of the natural human through anti-doping.

ACE ID genotype and the muscle strength and size response to unilateral resistance training

PURPOSE

To examine associations among the angiotensin I-converting enzyme (ACE) insertion (I)/deletion (D) polymorphism and the response to a 12-wk (2 d.wk) unilateral, upper-arm resistance training (RT) program in the trained (T, nondominant) and untrained (UT, dominant) arms.

METHODS

Subjects were 631 (mean+/-SEM, 24.2+/-0.2 yr) white (80%) men (42%) and women (58%). The ACE ID genotype was in Hardy-Weinberg equilibrium with frequencies of 23.1, 46.1, and 30.8% for ACE II, ID, and DD, respectively (chi=1.688, P=0.430). Maximum voluntary contraction (MVC) and one-repetition maximum (1RM) assessed peak elbow flexor muscle strength. Magnetic resonance imaging measured biceps muscle cross-sectional area (CSA). Multiple variable and repeated-measures ANCOVA tested whether muscle strength and size differed at baseline and pre- to post-RT among T and UT and ACE ID genotype.

RESULTS

Baseline muscle strength and size were greater in UT than T (P<0.001) and did not differ among ACE ID genotype in either arm (P >or= 0.05). In T, MVC increases were greater for ACE II/ID (22%) than DD (17%) (P<0.05), whereas 1RM (51%) and CSA (19%) gains were not different among ACE ID genotype pre- to post-RT (P >or= 0.05). In UT, MVC increased among ACE II/ID (7%) (P<0.001) but was similar among ACE DD (2%) pre- to post-RT (P >or= 0.05). In UT, 1RM (11%) and CSA (2%) increases were greater for ACE DD/ID than ACE II (1RM, 7%; CSA, -0.1%) (P<0.05). ACE ID genotype explained approximately 1% of the MVC response to RT in T and approximately 2% of MVC, 2% of 1RM, and 4% of CSA response in UT (P<0.05).

CONCLUSION

ACE ID genotype is associated with the contralateral effects of unilateral RT, perhaps more so than with the muscle strength and size adaptations that result from RT.

No correlation between circulating ACE activity and $$ {\user2{V}}{\mathbf{O}}_{{{\mathbf{2}}_{{{\mathbf{max}}}} }} $$ or mechanical efficiency in women

The insertion (I) variant of the angiotensin-1 converting enzyme (ACE) I/D genetic polymorphism is associated with lower circulating and tissue ACE activity. Some studies have also suggested associations of ACE I/D genotype with endurance phenotypes. This study assessed the relationships between circulating ACE activity, ACE I/D genotype, mechanical efficiency and the maximal rate of oxygen uptake in sedentary individuals. Sixty-two untrained women were tested for mechanical efficiency during submaximal cycle ergometry (delta and gross efficiencies during exercise between 40 and 80 W) and the maximal rate of oxygen uptake during incremental treadmill running. Respiratory variables were measured using indirect calorimetry. Venous blood was obtained for direct assay of circulating ACE activity, allowing for the assessment of correlations between two continuous variables, rather than a categorical analysis of endurance phenotype by genotype alone. ACE I/D genotype was also determined, and was strongly associated with circulating ACE activity (P < 0.0005). Neither circulating ACE activity (27.4 +/- 8.4 nM His-Leu-ml(-1)) nor ACE genotype showed a statistically significant association with any of the endurance phenotypes measured. The weak correlations observed included r = -0.122 (P = 0.229) for the relationship between delta efficiency (23.9 +/- 2.5%) and circulating ACE activity and r = 0.134 (P > 0.6) for the relationship between maximal aerobic power (149.1 +/- 22.9 ml kg(-2/3) min(-1)) and circulating ACE activity. The data do not support a role for systemic ACE activity in the regulation of endurance performance in sedentary individuals, extending this observation to a large female cohort.

Biomechanical muscle properties and angiotensin-converting enzyme gene polymorphism: a model-based study

Previous studies reported an association of angiotensin-converting enzyme (ACE) I/D gene polymorphism with physical performance. The study was based on the hypothesis that certain individual biomechanical muscle properties could be associated with ACE genotype and that they could influence athletes' physical performance. Movement-independent individual biomechanical muscle properties of 62 sports students were determined by applying a mathematical model to experimental data. Subjects exerted concentric and isometric contractions at a leg-press. The model was based on a Hill-type muscle model, a function describing the geometrical arrangement of human leg extensor muscles, and an exponential function describing muscle activation. Mouthwash samples were taken to determine the ACE genotypes. Several combinations of experimentally determined biomechanical properties served as input variables for a discriminant analysis. We were able to show that individual biomechanical muscle properties correlated with ACE I/D gene polymorphism. With a combination of certain individual muscle parameters based on a Hill-type muscle model, we were able to separate three individual ACE genotypes (II, ID, DD) in a significant way (P<0.03) and correctly classify 89% of the cases using a discriminant analysis. We conclude that local biomechanical muscle properties are influenced by ACE genotype.

Relationship between ace genotype and short duration aerobic performance development

We have previously demonstrated that, ACE D allele may be related with a better performance in short duration aerobic endurance in a homogeneous cohort with similar training backgrounds. We aimed to study the variation in the short-duration aerobic performance development amongst ACE genotypes in response to identical training programs in homogeneous populations. The study group consisted of 186 male Caucasian non-elite Turkish army recruits. All subjects had undergone an identical training program with double training session per day and 6 days a week for 6 months. Performances for middle distance runs (2,400 m) were evaluated on an athletics track before and after the training period. ACE gene polymorphisms were studied by PCR analysis. The distribution of genotypes in the whole group was 16.7% II, n=31; 46.2% ID, n=86; 37.1% DD, n=69. Subjects with ACE DD genotype had significantly higher enhancement than the ID (P<0.01) and II (P<0.05) genotype groups. Around 2,400 m performance enhancement ratios showed a linear trend as ACE DD>ACE ID>ACE II (P value for Pearson chi2=0.461 and P value for linear by linear association=0.001). ACE DD genotype seems to have an advantage in development in short-duration aerobic performance. This data in unison with the data that we have obtained from homogenous cohorts previously is considered as an existence of threshold for initiation of ACE I allele effectiveness in endurance performance. This threshold may be anywhere between 10 and 30 min with lasting maximal exercises.

Endothelial Nitric Oxide Synthase Polymorphisms Do Not Influence Pulmonary Artery Systolic Pressure at Altitude

Previous genetic association studies in high-risk subjects have suggested that polymorphisms in the gene encoding endothelial nitric oxide synthase (eNOS) may be associated with susceptibility to high altitude pulmonary edema (HAPE). We aimed to determine whether eNOS polymorphisms influence systolic pulmonary artery pressure measurements (PASP) in healthy trekkers ascending to high altitude. We examined two polymorphisms of the eNOS gene in Caucasian volunteers: Glu298Asp variant and 27-base pair (bp) variable number of tandem repeats polymorphism (27-bp VNTR). In 33 subjects, the relationships between polymorphisms and absolute pulmonary artery systolic pressure measurements (PASP), determined by echocardiography, were assessed at sea level and 1, 3, and 7 days after acute ascent by vehicle transport to 5200 m. As expected, there was a significant rise in pulmonary artery pressure on ascent to high altitude. By contrast, at sea level and at each time point at high altitude, no difference was found in mean PASP according to eNOS polymorphism. We found no association of Glu298Asp and 27-bp VNTR polymorphisms in the eNOS gene with PASP in a population of healthy trekkers at low or high altitude.

Angiotensin-Converting Enzyme Genotype Predicts Cardiac and Autonomic Responses to Prolonged Exercise

OBJECTIVES

The purpose of this study was to investigate the phenomenon of left ventricular (LV) dysfunction after ultraendurance exercise.

BACKGROUND

Subclinical LV dysfunction in response to endurance exercise up to 24 h duration has been described, but its mechanism remains elusive.

METHODS

We tested 86 athletes before and after the Adrenalin Rush Adventure Race using echocardiography, impedance cardiography, and plasma immunoassay.

RESULTS

At baseline, athletes demonstrated physiology characteristic of extreme endurance training. After 90 to 120 h of almost-continuous exercise, LV systolic and diastolic function declined (fractional shortening before the race, 39.6 +/- 0.65%; after, 32.2 +/- 0.84%, p < 0.001; mitral inflow E-wave deceleration time before the race, 133 +/- 5 ms; after, 160 +/- 5 ms, n = 48, p < 0.001) without change in loading conditions as defined by LV end-diastolic dimension and total peripheral resistance estimated by thoracic impedance. There was a compensatory increase in heart rate (before, 55 +/- 1.3 beats/min; after, 59 +/- 1.5 beats/min, p = 0.05), which left cardiac output unchanged, as well as significant-but-subclinical increases in brain natriuretic peptide and troponin I. In addition, we found that athletes who were homozygous for the intron-16 insertion polymorphism of the angiotensin-converting enzyme (ACE) gene exhibited a significantly greater decrease in fractional shortening than athletes who were homozygous for the deletion allele. Heterozygotes showed an intermediate phenotype. In addition, the deletion group manifest an enhanced sympathovagal balance after the race, as evidenced by greater power in the low-frequency component of blood pressure variability.

CONCLUSIONS

The ACE genotype predicts the extent of reversible subclinical LV dysfunction after prolonged exercise and is associated with a differential postactivity augmentation of sympathetic nervous system function that may explain it.

Association of increased cardiorespiratory fitness with low risk for clustering of metabolic syndrome components in asymptomatic men

BACKGROUND

From a preventive aspect, it is especially important to investigate the lifestyle risk factors associated with cardiovascular disease (CVD). The purpose of this study was to determine the relationship of increasing metabolic syndrome (MS) components across increasing levels of estimated cardiorespiratory fitness (CRF) in asymptomatic young to middle-aged men.

METHODS

We studied 449 consecutive asymptomatic men (47 +/- 7 years) who underwent a maximal treadmill exercise test according to the Bruce protocol. Cardiorespiratory fitness (CRF) was divided into tertiles based on metabolic equivalents (METs). The following MS components were studied: 1) waist circumference > 102 cm; 2) serum triglycerides > or = 150 mg/dL; 3) HDL cholesterol levels of < 40 mg/dL; 4) fasting blood glucose (FBG) > or = 110 mg/dL or 5) blood pressure > or = 130/85 mmHg or treated hypertension. Multinomial logistic regression was used to investigate the relationship between clustering of MS components and CRF as determined by metabolic equivalents (METs). We used polytomous logistic regression to determine the likelihood of clustering of increasing components of metabolic syndrome with intermediate (2nd tertile) and low (1st tertile) levels of CRF as compared to those with highest levels of CRF (3rd tertile).

RESULTS

Overall in the study population, zero, 1, 2 and > or = 3 (i.e., metabolic syndrome) risk factors for MS were observed in 29% (n = 129), 26% (n = 118), 22% (n = 98) and 23% (n = 104) men, respectively. The mean METS achieved in the study population was 10 +/- 2 (range 4-20). Nearly half (49%) of individuals with the highest levels of CRF had no MS risk factors whereas only 18% of those with low CRF (METS < 9) had no MS risk factors. On the other end of the spectrum, the prevalence of MS (> or = 3 MS risk factors) increased significantly across decreasing levels of CRF (6, 22, 33% p < 0.0001 for trend). Multivariable polytomous logistic regression (adjusting for age, smoking, cholesterol-lowering therapy) demonstrated that individuals with low CRF (1st tertile of METS) compared to those with highest CRF had 3.1- (p = 0.001) and 11.8- (p < 0.0001) fold higher risk of having 2 and > or = 3 MS components, respectively. Similar results were observed when the analyses was repeated adjusting for Framingham risk score.

CONCLUSIONS

Asymptomatic men with low levels of CRF have a greater likelihood for clustering of MS components and thus are at higher CVD risk. Further studies are needed to define the risk of cardiovascular disease in patients with intermediate levels of CRF and address which treatment strategies are most important given an individual's risk profile.

The associations of ACE polymorphisms with physical, physiological and skill parameters in adolescents

Genetic variation in the human Angiotensin I-Converting Enzyme (ACE) gene has been associated with many heritable traits, including physical performance. Herein we report the results of a study of several physical, physiological and skill parameters and lifestyle in 1,027 teenage Greeks. We show that there is a strong association (P < 0.001) between the ACE I/D (insertion/deletion) polymorphism and both handgrip strength and vertical jump in females, homozygotes for the I-allele exhibiting higher performance-related phenotype scores, accounting for up to 4.5% of the phenotypic variance. The association is best explained by a model in which the D-allele is dominant, with the mean phenotypic value in the I/D heterozygotes being close to that of the mean of the DD homozygotes. The association acts across the phenotype distribution in a classical polygenic manner. Other polymorphisms that define major ACE haplotypes in European populations (rs4424958, rs4311) show weaker associations with these performance-related phenotypes than does I/D. Similarly, diplotypes defined by these polymorphisms do not explain significantly larger amounts of the variance than I/D alone. As ACE I/D is the polymorphism most strongly associated with circulating ACE activity in European populations, we propose that the functional allelic differences that influence ACE activity also mediate the associations with the performance-related phenotypes studied here.

ACEPolymorphisms

Angiotensin converting enzyme (ACE) plays an essential role in two physiological systems, one leading to the production of angiotensin II and the other to the degradation of bradykinin. The wide distribution and multifunctional properties of these peptides suggest that ACE could be involved in various pathophysiological conditions. The discovery that ACE levels are under genetic control ushered in a new era of investigation; most studies focused on an insertion/deletion (I/D) polymorphism in intron 16 of the ACE gene as a marker for a functional polymorphism. Recently, many single nucleotide polymorphisms were detected in the gene and the search for the locations of functional polymorphisms became a topic of extensive investigation. Nevertheless, association studies on the I/D polymorphism and clinical outcomes continued, mostly with conflicting results. This article reviews the current state of knowledge regarding ACE polymorphisms and suggests that a functional polymorphism is most likely located between intron 18 and the 3' UTR. The potential existence of another functional polymorphism in the 5' UTR, however, cannot be excluded. This review also presents an overview of ACE function in different pathophysiological systems, and summarizes previous reports on ACE and clinical outcomes. Although findings on the I/D polymorphism and disorders like diabetic nephropathy and Alzheimer disease can be considered conclusive, reports on most of the cardiovascular phenotypes are still controversial. Genotypic and phenotypic misclassifications, insufficient power in some studies, and the presence of interaction with other genes or environmental factors are possible explanations for the contradictory findings.

Angiotensin-converting enzyme genotype and adherence to aerobic exercise training

Angiotensin-converting enzyme (ACE) has two common genetic variants: the insertion (I) and deletion (D) forms. ACE levels are greater in subjects with the D allele, and several studies suggest superior endurance performance in subjects with the I allele. The authors recently reported the results of a 6-month exercise training protocol examining the effect of apolipoprotein E on the lipid response. The present report examines the relationship of ACE genotype and exercise adherence. DNA samples were available for 110 subjects: 14 I/I, 52 I/D, and 44 D/D. Baseline and change in maximal oxygen uptake, body mass index, skinfold thickness, and serum lipids did not differ by ACE genotype, but adherence to exercise training was higher in I carriers than in D homozygotes. These preliminary results suggest that ACE genotype affects exercise adherence and raises the possibility that superior endurance capacity in subjects with the I allele is related to a genetic propensity to adhere to an exercise regimen.

Angiotensin II type I receptor gene polymorphism: anthropometric and metabolic syndrome traits

BACKGROUND

The renin angiotensin system is important in the regulation of vascular tone and fluid and electrolyte balance. The angiotensin converting enzyme gene (ACE) genotype has been shown to affect exercise response and glucose load response dependent on birth weight. Angiotensin II type I receptor (AGTR1) A1166C has previously been associated with the development of hypertension and coronary disease, but its metabolic effects have not been investigated.

METHOD

AGTR1 A1166C was genotyped by allele specific PCR in 378 individuals from Hertfordshire, UK, who had been characterised for metabolic syndrome traits.

RESULTS

Genotype counts were: AA, 183; AC, 170; CC, 25, consistent with Hardy-Weinberg equilibrium. The CC genotype was associated with significantly lower body mass index (by 1.7 units) in men (p = 0.03), and the same magnitude effect in women with significant lower weight in both genders (p = 0.01), also lower waist circumference and waist-hip ratio (p = 0.01) in men, with a trend for lower waist circumference in women also. Additionally, the CC genotype and/or C allele was associated with lower fasting glucose and insulin, and 30 and 120 min glucose in men (respectively, p = 0.08, 0.04, 0.01, 0.06). Lower means of systolic blood pressure, pulse pressure, cholesterol, and fasting triglyceride were also observed for the CC genotype in both genders though these were not statistically significant.

CONCLUSIONS

The AGTR1 1166 CC genotype appears to predispose to favourable anthropometric and metabolic traits, relative to cardiovascular risk.

Effects of acute hypoglycemia on motivation and cognitive interference in people with type 1 diabetes

AIMS

To examine the effect of acute hypoglycemia on motivation and cognitive interference in adult humans with type 1 diabetes.

METHODS

A hyperinsulinemic glucose clamp was used to either maintain euglycemia (arterialized blood glucose 4.5 mmol/L) or induce hypoglycemia (2.6 mmol/L) in 16 adults with type 1 diabetes, each of whom were studied on 2 separate occasions in a counterbalanced order. During each study condition, the subjects completed parallel tests of cognitive function. The Dundee Stress State Questionnaire (DSSQ) was administered before and after the cognitive function tests.

RESULTS

Hypoglycemia decreased task-relevant (P = 0.03) and increased task-irrelevant (P = 0.02) interference. Self-focus of attention was much higher after hypoglycemia than euglycemia (P = 0.02). Motivation declined to a similar extent during the euglycemia and hypoglycemia conditions (P = 0.07). Hypoglycemia produced a negative mood state with a significant fall in energy levels (P = 0.03) and a concomitant rise in anxiety level (P = 0.05). The subjective perception of concentration was unaffected during hypoglycemia (P = 0.14), and the scores for control and confidence did not fall (P = 0.19).

CONCLUSIONS

In people with type 1 diabetes, hypoglycemia causes a state of heightened self-awareness and distraction during active mental activity. This is likely to leave fewer processing resources available to allow completion of cognitive tasks. Acute hypoglycemia induces a state of significant worry and anxiety that is likely to affect the social, personal, and work activities of people with diabetes.

Growth hormone 1 (GH1) gene and performance and post-race rectal temperature during the South African Ironman triathlon

BACKGROUND

Some studies have suggested that the insertion allele of the ACE gene is associated with endurance performance, including the Ironman triathlon. It is possible that this association is due to genetic linkage between the ACE I/D locus and the T/A variant in intron 4 of the neighbouring GH1 gene. The A variant is associated with lower levels of growth hormone production. Growth hormone has multiple effects, especially on metabolism during exercise and recovery from exercise. Its production during exercise has also been shown to stimulate sweat rate and heat loss.

OBJECTIVE

To determine whether the GH1 gene is associated with the performance and/or post-race rectal temperatures of competitors in the South African Ironman triathlon.

METHODS

A total of 169 of the fastest finishing white male triathletes who completed the 2000 and/or 2001 South African Ironman triathlon and 155 control subjects were genotyped for the T/A variant in the GH1 gene. Post-race rectal temperature was also determined in 103 of these triathletes.

RESULTS

There was no significant difference in the frequency of this polymorphism in the GH1 gene when the fastest finishing triathletes were compared with the control subjects. Post-race rectal temperatures were, however, significantly higher in those triathletes with an AA genotype (mean (SD) 37.7 (0.8) degrees C) compared with those with a TT genotype (37.2 (0.8) degrees C) (p = 0.019).

CONCLUSIONS

The T/A polymorphism in intron 4 of the GH1 gene was not associated with performance of the fastest finishers of the South African Ironman triathlon. Post-race rectal temperatures were, however, significantly higher in the fastest finishing athletes, who were homozygous for a GH1 genotype associated with lower growth hormone production.

The bradykinin beta 2 receptor (BDKRB2) and endothelial nitric oxide synthase 3 (NOS3) genes and endurance performance during Ironman Triathlons

We have previously shown that the insertion allele of the angiotensin-converting enzyme (ACE) gene was over-represented in the fastest South-African-born finishers of the South African Ironman Triathlons. As ACE is a component of the skeletal muscle kallikrein-kinin system (KKS), the aim of this study is to determine if there are any further associations between polymorphisms within the BDKRB2 and NOS3 genes, which encode for the KKS components, bradykinin beta(2) receptor and nitric oxide synthase, respectively, and ultra-endurance performance during the Ironman Triathlons. Four-hundred and forty-three male Caucasian triathletes who completed the 2000 and/or 2001 South African Ironman Triathlons and 203 healthy Caucasian male control subjects were genotyped for the functional -9/+9 polymorphism within exon 1 of the BDKRB2 gene and the G894T NOS3 gene polymorphisms. The BDKRB2 -9/-9 genotype occurred at a significantly higher frequency when the triathlete group (27.0%) was compared with the control group (19.3%, P=0.035). When divided into tertiles, there was also a significant linear trend for the NOS3 GG genotype distribution among the fastest (35.0%), middle (40.4%) and slowest (46.9%) finishers (P=0.039). The overall finishing times of the triathletes with an NOS3 GG genotype together with a BDKRB2 +9 allele were significantly slower than those with other genotype combinations (P=0.001). The NOS3/BDKRB2 genotype (beta=-0.150, B=-31.48, P=0.002), together with body mass index and age, accounted for 14.6% of the variance in the overall race time for the triathlon. In conclusion, both the NOS3 and BDKRB2 genes are associated with the actual performance during the Ironman Triathlons.

Histochemical characteristics of soleus muscle in angiotensin-converting enzyme gene knockout mice

We examined the histochemical characteristics of soleus muscle in the angiotensin-converting enzyme (ACE) gene (Ace in mice, ACE in humans) knockout mice. Serial sections of soleus muscle of wild-type (Ace+/+, n=20) and heterozygous mutant (Ace+/-, n=24) mice were stained for myosin adenosine triphosphatase activity to identify different muscle fiber types. Capillaries were visualized by amylase-periodic acid-Schiff staining. ACE activity in the serum and gastrocnemius muscle was higher in male mice than in female mice. Female and male Ace+/- mice had markedly lower ACE activity in the serum and the gastrocnemius muscle than did female and male Ace+/+ mice, respectively. In both male and female mice, the composition of fiber types (type I and IIa) did not differ significantly between Ace+/+ and Ace+/- mice. There was no significant gender difference in capillary density. Ace+/- mice had significantly more capillaries around type IIa fibers (5.44 +/- 0.18 vs. 5.01 +/- 0.13, p<0.05) than Ace+/+ mice. The differences in the number of capillaries around type I fibers and in the number of capillaries around per fiber (capillary:fiber ratio) between Ace+/- and Ace+/+ mice were not significant (p<0.1). There was no significant difference in the mean cross-sectional area occupied by one capillary and the number of capillaries per fiber area between Ace+/+ and Ace+/- mice. In conclusion, knockout of the Ace gene in mice increased capillary density, as expressed by the mean number of capillaries around type IIa fibers. This finding suggests a possible mechanism for the cardioprotective effects of ACE inhibitors.

Effects of dominant somatotype on aerobic capacity trainability

PURPOSE

This study examined the association between dominant somatotype and the effect on aerobic capacity variables of individualised aerobic interval training.

METHODS

Forty one white North African subjects (age 21.4+/-1.3 years; Vo2max = 52.8+/-5.7 ml kg(-1) min(-1)) performed three exercise tests 1 week apart (i) an incremental test on a cycle ergometer to determine Vo2max and Vo2 at the second ventilatory threshold (VT2); (ii) a VAM-EVAL track test to determine maximal aerobic speed (vVo2max); and (iii) an exhaustive constant velocity test to determine time limit performed at 100% vVo2max (tlim100). Subjects were divided into four somatometric groups: endomorphs-mesomorphs (Endo-meso; n = 9), mesomorphs (Meso; n = 11), mesomorphs-ectomorphs (Meso-ecto; n = 12), and ectomorphs (Ecto; n = 9). Subjects followed a 12 week training program (two sessions/week). Each endurance training session consisted of the maximal number of successive fractions for each subject. Each fraction consisted of one period of exercise at 100% of vVo2max and one of active recovery at 60% of vVo2max. The duration of each period was equal to half the individual tlim100 duration (153.6+/-39.7 s). After the training program, all subjects were re-evaluated for comparison with pre-test results.

RESULTS

Pre- and post-training data were grouped by dominant somatotype. Two way ANOVA revealed significant somatotype-aerobic training interaction effects (p<0.001) for improvements in vVo2max, Vo2max expressed classically and according to allometric scaling, and Vo2 at VT2. There were significant differences among groups post-training: the Meso-ecto and the Meso groups showed the greatest improvements in aerobic capacity.

CONCLUSION

The significant somatotype-aerobic training interaction suggests different trainability with intermittent and individualised aerobic training according to somatotype.

Association between angiotensin I-converting enzyme insertion/deletion gene functional polymorphism and novelty seeking personality in healthy females

A certain type of personality is at risk for developing psychiatric diseases. Several lines of evidence support the interaction between brain angiotensins and central catecholamine systems, and suggest that angiotensin I-converting enzyme (ACE) may be a reasonable candidate gene for psychiatric disorders. The present study examined the possibility that ACE insertion (I)/deletion (D) functional polymorphism might be associated with particular personality traits. Healthy Japanese subjects (N=184) were administered the Temperament and Character Inventory (TCI) and the NEO Personality Inventory Revised version (NEO-PI-R), and their ACE I/D polymorphisms were determined. There was an ethnic difference in the genetic distribution of ACE I/D between Japanese (D=34.5%) and Caucasians (D=55.2%). We found that the scores of novelty seeking (NS) in the Low-ACE group (II genotype) of healthy female subjects were significantly lower than those in the High-ACE group (ID or DD genotype) (p=0.018). Our findings suggested that the ACE I/D polymorphism might be associated with the NS personality trait in females, but not males. Taking into account the effects of multiple comparisons, this result should be interpreted with caution, and needs confirmation in a larger sample.

Effects of interaction between angiotensin I-converting enzyme polymorphisms and lifestyle on adiposity in adolescent Greeks

Genetic variation in the human angiotensin I-converting enzyme (ACE) gene has been associated with many heritable traits, including obesity. Herein, we report the results of a study of obesity-related phenotypes and lifestyle in 1016 teen-aged Greeks. We show that there is a strong association (p = 0.001) between subcutaneous fat and the ACE insertion/deletion (I/D) polymorphism in females, possession of genotypes containing the D allele being associated with increased fat thickness. This association is strongest in females who participate in no extra exercise and accounts for 6.5% of the phenotypic variance in fat thickness by ANOVA. The association is additive, with the mean phenotypic values in heterozygotes intermediate between the means of the two homozygotes, and the association acts at both extremes of the fat thickness distribution in a classical polygenic manner. Other ACE polymorphisms (rs4424958, rs4311) that define major haplotypes in European populations fail to provide stronger associations with the subcutaneous fat phenotype. Because ACE I/D is the polymorphism most strongly associated with circulating ACE levels in European populations, we propose that the functional allelic differences that influence circulating ACE levels also mediate the associations with the obesity-related phenotypes studied here.

The genetics of muscle atrophy and growth: the impact and implications of polymorphisms in animals and humans

Much of the vast diversity we see in animals and people is governed by genetic loci that have quantitative effects of phenotype (quantitative trait loci; QTLs). Here we review the current knowledge of the genetics of atrophy and hypertrophy in both animal husbandry (meat quantity and quality), and humans (muscle size and performance). The selective breeding of animals for meat has apparently led to a few genetic loci with strong effects, with different loci in different animals. In humans, muscle quantitative trait loci (QTLs) appear to be more complex, with few "major" loci identified to date, although this is likely to change in the near future. We describe how the same phenotypic traits we see as positive, greater lean muscle mass in cattle or a better exercise results in humans, can also have negative "side effects" given specific environmental challenges. We also discuss the strength and limitations of single nucleotide polymorphisms (SNP) association studies; what the reader should look for and expect in a published study. Lastly we discuss the ethical and societal implications of this genetic information. As more and more research into the genetic loci that dictate phenotypic traits become available, the ethical implications of testing for these loci become increasingly important. As a society, most accept testing for genetic diseases or susceptibility, but do we as easily accept testing to determine one's athletic potential to be an Olympic endurance runner, or quarterback on the high school football team.

The role of cardiopulmonary fitness and its genetic influences on surgical outcomes

Background

Outcome after major surgery remains poor in some patients. There is an increasing need to identify this cohort and develop strategies to reduce postsurgical morbidity and mortality. Central to outcome is the ability to mount cardiovascular output in response to the increased oxygen demand associated with major surgery.

Methods

A medline search was performed using keywords to identify factors that affect, and genetic influences in, disease and outcome from surgery, and all relevant English language articles published between 1980 and 2005 were retrieved. Secondary references were obtained from key articles.

Results

Preoperative cardiopulmonary exercise testing assesses patient fitness, highlights those at particular risk and, combined with triage to critical care, facilitates significant improvement in surgical outcome. However, genetic factors also influence responses to increased oxygen demand, and some patients are genetically predisposed to mounting increased inflammatory responses, which raise oxygen demand further. Polymorphisms in genes influencing fitness (angiotensin converting enzyme) and immune and inflammatory responses (such as interleukin 6) may associate with surgical outcome.

Conclusions

Development of preoperative screening methods like cardiopulmonary exercise testing and genotype analysis to identify index factors may permit better patient stratification, provide targets for future tailored treatments and so improve surgical outcome.

No association between Angiotensin Converting Enzyme (ACE) gene variation and endurance athlete status in Kenyans

East African runners are continually successful in international distance running. The extent to which genetic factors influence this phenomenon is unknown. The insertion (I) rather than deletion (D) of a 287 bp fragment in the human angiotensin converting enzyme (ACE) gene is associated with lower circulating and tissue ACE activity and with endurance performance amongst Caucasians. To assess the association between ACE gene variation and elite endurance athlete status in an African population successful in distance running, DNA samples were obtained from 221 national Kenyan athletes (N), 70 international Kenyan athletes (I), and 85 members of the general Kenyan population (C). Blood samples were obtained from C and assayed for circulating ACE activity. ACE I/D (rs????--from NCBI SNPdb first time poly mentioned) genotype was determined, as was genotype at A22982GD (rs????--from NCBI SNPdb first time poly mentioned) which has been shown to associate more closely with ACE levels in African subjects than the I/D polymorphism. ACE I/D and A22982G genotypes explained 13 and 24% of variation in circulating ACE activity levels (P = 0.034 and <0.001 respectively). I/D genotype was not associated with elite endurance athlete status (df = 4, chi(2) = 4.1, P=0.39). In addition, genotype at 22982 was not associated with elite endurance athlete status (df = 4, chi(2) = 5.7, P = 0.23). Nor was the A allele at 22982, which is associated with lower ACE activity, more prevalent in N (0.52) or I (0.41) relative to C (0.53). We conclude that ACE I/D and A22982G polymorphisms are not strongly associated with elite endurance athlete status amongst Kenyans.

Hypoglycaemia and cognitive function

Acute hypoglycaemia impairs cerebral function, and available data indicate that cognitive performance becomes impaired at a blood glucose level of 2.6-3.0 mmol/l in healthy subjects. Methodological problems limit comparisons between studies, but in general complex tasks are more sensitive to hypoglycaemia than simple tasks, and some cognitive abilities are completely abolished. The onset of hypoglycaemic cognitive dysfunction is immediate, but recovery may be considerably delayed. There is persuasive evidence of adaptation to hypoglycaemia, partly due to increased brain glucose uptake capacity, although other mechanisms may exist. Patients who are exposed to chronic or recurrent hypoglycaemia become remarkably tolerant to the state, but this is insufficient to prevent severe hypoglycaemia with neuroglycopenic decompensation, probably because symptomatic and counterregulatory responses adapt even more. During experimental hypoglycaemia, administration of non-glucose cerebral fuels preserves cognitive function. However, little progress has been made as yet towards protecting cognitive function during hypoglycaemia in clinical practice. The chronic effects of recurrent hypoglycaemia remain contentious. There are numerous case reports of hypoglycaemic brain damage and of cognitive deterioration attributed to repeated severe hypoglycaemia. The major prospective studies, including the Diabetes Control and Complications Trial, did not report cognitive declines in intensively treated patients, but had unrepresentative study populations and may have been too short to detect such effects. Structural and functional brain changes are not only associated with recurrent severe hypoglycaemia, but also with hyperglycaemia and early disease onset and may in part be due to hyperglycaemic microvascular disease. Children may be more prone to acute metabolic insults, and there is evidence of developmental disadvantage associated with hypoglycaemic episodes.

Effects of angiotensin-converting enzyme polymorphism on aortic elastic parameters in athletes

BACKGROUND

Physiologic adaptations in an athlete's heart include increased left and right ventricular chamber size, left ventricular wall thickness and mass. Angiotensin-converting enzyme (ACE) is a key enzyme in angiotensin II production causing cardiac hypertrophy. The cloning of the ACE gene has made it possible to identify a deletion (D)-insertion (I) polymorphism that appears to affect the level of serum ACE activity. Therefore, the ACE genes, which have been shown to be polymorphic, could be candidate genes for large-artery stiffness.

METHODS

56 endurance athletes and 46 sedentary subjects were included in this study, and they underwent both complete echocardiographic examination, and analysis of ACE insertion (I) and deletion (D) allele frequencies in peripheral blood. The aortic diameter was recorded by M-mode echocardiography at a level 3 cm above the aortic valve. Aortic systolic diameter was measured at the time of full opening of the aortic valve, and diastolic diameter was measured at the peak of QRS. Aortic strain, stiffness index and distensibility were calculated.

RESULTS

Left ventricular mass index and left ventricular ejection fraction were significantly higher in athletes than controls (p < 0.001). The aortic distensibility index and strain were significantly greater in athletes compared with controls (respectively: 5.8 +/- 2.7 vs. 4.7 +/- 1.8 cm(-2) dyn(-1) 10(-6), p = 0.017; 12.3 +/- 2.4 vs. 9.3 +/- 3.1, p < 0.001). The aortic stiffness index was significantly lower in athletes than in controls (4.8 +/- 1.9 vs. 6.1 +/- 2.1, p < 0.001). The aortic distensibility index and strain were statistically different in ACE DD vs. DI groups and DD vs. II groups of athletes. The aortic stiffness index was statistically different in ACE DD vs. II groups of athletes. Aortic parameters were similar according to ACE genotypes in controls.

CONCLUSION

The results of this study indicate that aortic distensibility was increased by prolonged training in endurance athletes, particularly in those with the ACE II genotype. This effect represents an extracardiac adaptation to chronic prolonged training in athletes.

ACE Genotype May Have an Effect on Single versus Multiple Set Preferences in Strength Training

A polymorphic variant of the human angiotensin converting enzyme (ACE) gene was identified. The 'D' (rather than 'I') variant was associated with improvements in strength related to physical training. We set out to determine whether the response to different patterns of strength training might also differ. Ninty-nine Caucasian male non-elite athletes were randomly allocated into one of three groups: 31 non-training/control (CG: 31), single-set (SSG: 35) and multiple-set (MSG: 33). SSG and MSG trained three times a week for 6 weeks. Both training groups were underwent a strength-training program with two mesocycles (12-15 repetition maximum (RM) and 8-12 RM mesocycles). One RM loads in half squat and bench press were assessed before training and after the first and second mesocycles. ACE polymorphisms analysed by polymerase chain reaction (PCR) methods. Subjects with ACE II genotype in the MST group had improved strength development in 12-15 RM, while SST and MST groups had similar gains in 8-12 RM. Subjects with ACE DD genotype in both the SSG and the MSG had similar benefits from both 12-15 RM and 8-12 RM. Strength gains for subjects with ACE ID genotype in the SSG were similar to MSG gains in response to 8-12 RM loads but not with 12-15 RM loads. Additionally, subjects with DD genotype had superior strength gains in both strength training groups. Tailoring strength training programmes (single-set vs. multiple set) according to the athlete's ACE genotype may be advantageous.

The inherent complexities of gene-environment interactions

The article outlines the complexities of gene-environment interactions in the determination of human disease, especially as they relate to aging, and stresses the importance of continuing such studies, in spite of their inherent difficulties. First, a capsule review of the literature pertaining to studies of gene-environment interactions is presented, and designs and methodologies used to detect these interactions are briefly discussed. Second, research questions and problems that can be addressed as outcomes of gene-environment interaction studies are exemplified. Third, a number of illustrative examples of gene-environment interactions are presented. Fourth, various types of gene-environment interactions are briefly discussed. Fifth, concluding remarks are offered, and possibilities of studying gene-environment interaction within social and biological research on aging are outlined.

Gene-nutrition interaction in human performance and exercise response

Recent advances in human performance research have revealed new insight into the many factors that influence how an individual responds to exercise training. Response to exercise interventions is often highly variable among individuals, however, and exercise response may be mediated in large part by variation in genes and nutrition and by gene-environment interactions. It is well established that the quality and quantity of nutritional intake play a critical role in response to training and in athletic performance. The body's adaptation to exercise is also the result of changes in expression of genes mediated not only by exercise but by multiple factors, including the interaction between exercise, components of dietary intake, and genetic variation. This review explores the effects of genetic variation and gene-nutrition interactions in response to exercise training and athletic performance.

Genes and human elite athletic performance

Physical fitness is a complex phenotype influenced by a myriad of environmental and genetic factors, and variation in human physical performance and athletic ability has long been recognised as having a strong heritable component. Recently, the development of technology for rapid DNA sequencing and genotyping has allowed the identification of some of the individual genetic variations that contribute to athletic performance. This review will examine the evidence that has accumulated over the last three decades for a strong genetic influence on human physical performance, with an emphasis on two sets of physical traits, viz. cardiorespiratory and skeletal muscle function, which are particularly important for performance in a variety of sports. We will then review recent studies that have identified individual genetic variants associated with variation in these traits and the polymorphisms that have been directly associated with elite athlete status. Finally, we explore the scientific implications of our rapidly growing understanding of the genetic basis of variation in performance.

Association Between the ACE I/D) Gene Polymorphism and Physical Performance in a Homogeneous Non-Elite Cohort

Background: I/D polymorphism of the ACE gene may be associated with better endurance performance and a stronger response to exercise training. The aim of this study was to investigate the association between ACE gene polymorphism and athletic performance in a homogeneous cohort. Methods: Eighty-eight male non-elite Caucasian Turkish athletes with similar training backgrounds for at least for 6 months were studied for ACE gene polymorphisms by PCR analysis. Performance on the 60-meter sprint and middle-distance running tests were evaluated. Results: The distributions of the ACE I/D genotypes were 20.5%, 40.9%, and 38.6% for II, ID, and DD polymorphisms in the whole group (N = 88), respectively. The ACE DD genotype frequency was significantly higher in the superior group (56.7%) than in the poor (37.9%) and mediocre (20.7%) group in middle-distance running performance (χ2 = 11.778; p = 0.019). Conclusion: The ACE DD genotype may be related to better short-duration aerobic endurance performance. Larger homogeneous cohorts may help clarify the association between ACE I/D polymorphism and physical performance. Key words: genetics, endurance performance, DNA, sprint

Angiotensin-Converting Enzyme Genotype is Not Associated With Exercise Capacity or the Training Effect of Cardiac Rehabilitation in Patients After Acute Myocardial Infarction

BACKGROUND

The relationship of the genotype for the angiotensin-converting enzyme (ACE) with exercise capacity or training effects has been studied in athletes or healthy persons, but recently the ACE DD genotype was reported to be associated with decreased exercise capacity in patients with congestive heart failure. Therefore, in the present study the association between the ACE genotype and exercise capacity was investigated in patients with acute myocardial infarction (AMI) participating in cardiac rehabilitation (CR) for 3 months.

METHODS AND RESULTS

The study population comprised 168 patients stratified as II (n=75), ID (n=67), and DD (n=26) according to ACE genotype. Baseline left ventricular ejection fraction (LVEF) was similar among the genotype groups. In all patients, exercise capacity (peak work rate (PWR) and peak oxygen uptake (PVO 2)) significantly increased after CR. However, no differences were observed in PWR and PVO2 among the genotype groups at baseline or after CR. The results were similar even when analyzed in 60 patients with left ventricular (LV) dysfunction (LVEF <45%).

CONCLUSION

The present study suggests that there is no association between ACE I/D polymorphism and exercise capacity in patients after AMI, even with LV dysfunction. Furthermore, ACE genotype may have no influence on the effects of CR after AMI.

The human gene map for performance and health-related fitness phenotypes: the 2003 update

This review presents the 2003 update of the human gene map for physical performance and health-related fitness phenotypes. It is based on peer-reviewed papers published by the end of 2003 and includes association studies with candidate genes, genome-wide scans with polymorphic markers, and single-gene defects causing exercise intolerance to variable degrees. The genes and markers with evidence of association or linkage with a performance or fitness phenotype in sedentary or active people, in adaptation to acute exercise, or for training-induced changes are positioned on the genetic map of all autosomes and the X chromosome. Negative studies are reviewed but a gene or locus must be supported by at least one positive study before being inserted on the map. By the end of 2000, 29 loci were depicted on the first edition of the map. In contrast, the 2003 human gene map for physical performance and health-related phenotypes includes 109 autosomal gene entries and QTL, plus two on the X chromosome. Moreover, there are 15 mitochondrial genes in which sequence variants have been shown to influence relevant fitness and performance phenotypes.

Performance at altitude and angiotensin I-converting enzyme genotype

The "insertion" (I) rather than "deletion" (D) variant of the human angiotensin-converting enzyme (ACE) gene is associated with both lower tissue ACE activity and elite performance at high altitude. We examined whether the onset of acute mountain sickness (AMS), and further performance on reaching the summit of Mt. Blanc are influenced by the ACE I/D polymorphism. Two hundred and eighty-four climbers (235 males, [37.0 (11.0 years], (86 DD, 142 ID, 56 II)) had assessment of their AMS status upon arrival to the Gouter hut (3,807 m) on day 1, and again on day 2 after an attempted ascent to the summit of Mt. Blanc (4,807 m). Success in reaching the summit was genotype dependent (87.7% of DD, 94.9% of ID and 100% of II individuals; P=0.048); I allele frequency for those reaching the summit was 0.47 compared to 0.21 for those who did not (P=0.01). The onset of AMS on day 1 appeared to be dependent on genotype (P=0.003), but with those heterozygous being less affected. ACE genotype was not associated either with AMS onset or severity on day 2. Thus, ACE I/D genotype is associated with successful high altitude ascent in this prospective study-an association not explicable by genotype-dependence of AMS onset or severity. Values are given as mean (SD) unless otherwise stated.

Polymorphisms of renin-angiotensin system genes with high-altitude pulmonary edema in Japanese subjects

STUDY OBJECTIVES

The renin-angiotensin system (RAS), including angiotensin-converting enzyme (ACE) and angiotensin II type 1 receptor (AT(1)R), plays an important role in the pathogenesis of pulmonary hypertension, which is suggested to be critical in the development of high-altitude pulmonary edema (HAPE). Investigating the associations of the polymorphisms in the genes of RAS with HAPE is to elucidate the genetic background underlying this disease.

DESIGN

A cross-sectional, case-control study.

SETTING

Shinshu University Hospital, Matsumoto, Japan.

PARTICIPANTS

Forty-nine HAPE-susceptible (HAPE-s) subjects with a history of HAPE, and 55 healthy climbers with HAPE resistance (HAPE-r).

INTERVENTIONS

Twenty-one of 49 HAPE-s subjects underwent right cardiac catheterization.

MEASUREMENTS AND RESULTS

The insertion/deletion polymorphism in the ACE gene (ACE-I/D) was investigated by polymerase chain reaction (PCR). There was no significant difference of the distribution of the ACE-I/D polymorphism between the HAPE-s and HAPE-r groups. The A(1166)C and G(1517)T single-nucleotide polymorphisms (SNPs) in AT(1)R gene were investigated by the PCR following digested by corresponding restricted endonuclease enzymes. The distribution of the G(1517)T SNP was significantly different between the two groups (p = 0.012). The pulmonary hemodynamics of the 21 HAPE-s subjects were retrospectively examined. The pulmonary artery pressure (PAP), pulmonary vascular resistance (PVR), and PVR index (PVRI) were all significantly increased on hospital admission. Moreover, the PVR and PVRI were significantly higher in the HAPE-s subjects with D positivity than in the HAPE-s subjects with I positivity (PVR, p = 0.015; PVRI, p = 0.028), while the PAP did not show any significant difference between the two subgroups.

CONCLUSIONS

The ACE-I/D polymorphism is not associated with HAPE susceptibility in Japanese subjects. The AT(1)R gene polymorphisms may likely associate with HAPE susceptibility. The D allele of the ACE-I/D polymorphism probably contributes to the hyperresponsive PVR and PVRI to acute hypoxia.

Association of medically unexplained fatigue with ACE insertion/deletion polymorphism in Gulf War veterans

Genes associated with muscle metabolism and physical endurance were evaluated for variants that may contribute to the etiology of medically unexplained severe and chronic fatigue. Subjects included 49 Gulf War veterans and 61 nonveterans with chronic fatigue syndrome (CFS) or idiopathic chronic fatigue (ICF) and 30 veterans and 45 nonveterans who served as healthy controls. Increased risk for CFS/ICF was associated with alterations of the insertion/deletion (I/D) polymorphism in the angiotensin-converting enzyme gene within the Gulf War veteran sample only. The I allele frequency was decreased in affected versus unaffected veterans (0.15 versus 0.48; odds ratio [OR], 5.08; 95% confidence interval [CI], 1.97-13.35; P < 0.0001). Correspondingly, the II genotype was decreased fourfold in affected veterans (0.08 versus 0.35; OR = 5.87; 95% CI: 1.21-28.36; P = 0.02), and the DD genotype was increased twofold (0.78 versus 0.39; OR, 5.4; 95% CI, 1.6-18.4; P = 0.007). Veterans with the DD genotype were eight times more likely to develop CFS/ICF than were those with the II genotype (OR, 8.30; 95% CI, 1.50-56.09; P = 0.009).

The ACE Gene and Endurance Performance during the South African Ironman Triathlons

PURPOSE

Several studies have suggested that the insertion (I) variant rather than the deletion (D) variant of the human angiotensin-converting enzyme (ACE) gene is associated with elite endurance performance. The aim of this study was to determine whether the ID polymorphism is associated with the performance of the fastest finishers of the South African Ironman Triathlons.

METHODS

A total of 447 Caucasian male triathletes of a variety of nationalities and athletic ability who completed either the 2000 or 2001 South African Ironman Triathlons and 199 Caucasian male control subjects were genotyped for the ACE ID polymorphism.

RESULTS

There was a significantly higher frequency of the I allele in the fastest 100 South African-born finishers (103 I, 51.5% and 97 D, 48.5%) compared with the 166 South African-born control subjects (140 I, 42.2% and 192 D, 57.8%) (P = 0.036). There was also a significant linear trend for the allele distribution among the fastest 100 finishers (I allele = 51.5%), slowest 100 finishers (I allele = 47.5%), and control (I allele = 42.2%) South African-born subjects (P = 0.033). There was, however, no significant difference in the ACE genotype or allele frequencies when athletes born outside South Africa were analyzed.

CONCLUSION

To our knowledge this is the first study that has examined the effect of an athlete's ACE genotype on their actual performance during an ultra-endurance race. The I allele of the ACE gene was associated with the endurance performance of the fastest 100 South African-born finishers in these triathlons.

The genetic basis of high-altitude pulmonary oedema

High-altitude pulmonary oedema (HAPE) is a potentially fatal condition affecting fit and previously well individuals at altitudes in excess of 3000 m. This article discusses the mechanisms of HAPE, considers the contribution of hypoxic pulmonary vasoconstriction and alterations in sodium transport to the pathological process. It discusses the various biochemical mediators such as nitric oxide (NO), endothelin-1 (ET-1), and the renin-angiotensin-aldosterone system (RAS) that may be involved and considers possible oxygen-sensing mechanisms involved in hypoxic adaptation such as hypoxia-inducible factor-1 (HIF-1). Those who have had HAPE once run an unpredictable but significant risk of recurrence; therefore, there may be a constitutional or genetic component in its aetiology. This paper considers the possible involvement of genes that may be involved in physiological adaptation to hypoxia (e.g., angiotensin-1 [AT(1)]-converting enzyme [ACE], tyrosine hydroxylase, serotonin transporter [5-HTT], and endothelial NO synthase [eNOS] genes). As yet, no formal association has been identified between an identified genetic polymorphism and HAPE, but genetic variation provides a possible mechanism to explain interindividual variation in response to hypoxia and enhanced or reduced performance at altitude.

Pharmacoepidemiology and disability in older adults: can medications slow the age-related decline in physical function?

Age-related disability and loss in physical function are growing public health priorities. Loss in physical function seriously threatens the independence and quality of life of older adults and has a significant social and economic impact on our society. Despite the fact that the negative impact of adverse drug reaction and inappropriate drug use on disability has been widely studied, there is limited evidence regarding the efficacy of pharmacological interventions to prevent decline in physical function among older populations. The effect of statins, angiotensin-converting enzyme inhibitors and testosterone on physical performance in older adults are reviewed. In clinical studies these drugs have recently shown promising effects on the prevention of disability and decline in physical function in older adults. The findings of these studies are not definite and need to be confirmed in large clinical trials.

Does the association of habitual physical activity with the metabolic syndrome differ by level of cardiorespiratory fitness?

OBJECTIVE

Cardiovascular fitness (VO(2max)) and physical activity are both related to risk of metabolic disease. It is unclear, however, whether the metabolic effects of sedentary living are the same in fit and unfit individuals. The purpose of this study was, therefore, to describe the association between physical activity and the metabolic syndrome and to test whether fitness level modifies this relationship.

RESEARCH DESIGN AND METHODS

Physical activity was measured objectively using individually calibrated heart rate against energy expenditure. VO(2max) was predicted from a submaximal exercise stress test. Fat mass and fat-free mass (FFM) were calculated using impedance biometry. A metabolic syndrome score was computed by summing the standardized values for obesity, hypertension, hyperglycemia, insulin resistance, hypertriglyceridemia, and the inverse level of HDL cholesterol and was expressed as a continuously distributed outcome. To correct for exposure measurement error, a random subsample (22% of cohort) re-attended for three repeat measurements in the year following the first assessment.

RESULTS

The relationship of VO(2max) (ml O2.kg(FFM)(-1).min(-1)) and the metabolic syndrome score was of borderline significance after adjusting for age, sex, physical activity, and measurement error (beta = -0.58, P = 0.06). The magnitude of the association between physical activity (kJ.d(-1).kg(FFM)(-1)) and the metabolic syndrome was more than three times greater than for VO(2max) (standardized beta = -1.83, P = 0.0042). VO(2max), however, modified the relationship between physical activity energy expenditure and metabolic syndrome (P = 0.036).

CONCLUSIONS

This study demonstrates a strong inverse association between physical activity and metabolic syndrome, an association that is much steeper in unfit individuals. Thus, prevention of metabolic disease may be most effective in the subset of unfit inactive people.