The interleukin-6 promoter polymorphism is associated with elevated leukocyte, lymphocyte, and monocyte counts and reduced physical fitness in young healthy smokers.

Smoking and interleukin-6 are important factors in driving inflammation. This study assessed the relationship between smoking, interleukin-6 genotype, physical fitness, and peripheral blood count in healthy young men. For this interleukin-6 promoter polymorphism -174 genotype-phenotype association study 1,929 healthy German male aviators recruited at the central German Air Force Institute of Aviation Medicine were stratified by smoking habits. Cardiovascular fitness was expressed as maximal physical working capacity (PWCmax) in watts per kilogram body weight as assessed by maximal exercise testing by cycle ergometry up to physical exhaustion. Smokers had higher leukocyte and lymphocyte counts than nonsmokers and lower PWCmax. In the overall study population the C allele of the interleukin-6 polymorphism was weakly associated with elevated leukocytes and lymphocytes; in nonsmokers the interleukin-6 polymorphism was not associated with altered phenotypes, but in smokers the interleukin-6 C allele was associated with higher leukocytes, lymphocytes, and monocytes and with lower PWCmax. Smoking is thus associated with elevated leukocytes and lymphocytes and with reduced physical fitness. Gene carriers with the interleukin-6 C allele may suffer particularly from cigarette smoking.

Relation between the angiotensinogen (AGT) M235T gene polymorphism and blood pressure in a large, homogeneous study population.

The aim of this study was to assess the association of the angiotensinogen M235T polymorphism with arterial blood pressure (BP) at rest and under physical stress in a homogeneous large-scale study population. In all, 1903 men who passed routine medical examination for military flying duty were recruited. BP and heart rate were measured at rest, during, and after bicycle ergometry. Genotyping for the AGT M235T polymorphism was carried out by PCR and RFLP technique. The AGT T235 allele was associated with a significantly higher diastolic BP (n=1903; MM 81+/-8, MT 83+/-7, TT 83+/-8; P=0.003). Pulse pressure (PP) at rest differed significantly between AGT genotypes (n=1903; MM 51+/-10 mmHg, MT 49+/-10 mmHg, TT 49+/-10 mmHg; P=0.001). During physical activity, BP values showed no significant difference between genotypes. In healthy young men, the AGT T235 allele is significantly associated with elevated diastolic BP but also reduced PP at rest. During physical activity, the AGT polymorphism had no impact on blood pressure, indicating the existence of other counteracting mechanisms, which might balance the influence of this gene.

Relation of body mass index, physical fitness, and the cardiovascular risk profile in 3127 young normal weight men with an apparently optimal lifestyle.

Obesity is a well-accepted cardiovascular risk factor associated with hypertension and hyperlipidaemia. A body mass index (BMI) within the range of 18.5-25 kg/m(2) is considered normal. To prevent cardiovascular diseases regular physical activity and abstinence from smoking are strongly recommended. Since it is not evident that a lower optimal threshold exists concerning cardiovascular risk factors if other lifestyle conditions are apparently optimised, we studied the relation between BMI and vascular risk factors in 3127 hyperhealthy Caucasian males. They were aged between 18 and 23 y, were nonsmokers, without regular alcohol intake, and had at least 3 h of sports activity per week. Their BMI was below 25 kg/m(2). Low BMI revealed to be significantly associated with high physical fitness, low blood pressure, and low serum lipids. The lower the BMI was, the more favourable these parameters were. Thus, the threshold for an optimal BMI concerning cardiovascular risk factors might be far below 25 kg/m(2) even if other lifestyle conditions are apparently optimal.

Prevalence of the metabolic syndrome in military and civilian flying personnel.

BACKGROUND: The metabolic syndrome (MS) affects 20-30% of the middle-aged population in highly industrialized countries, consisting of a cluster of diseases including obesity, hypertension, dyslipoproteinemia and glucose intolerance. HYPOTHESIS: If the population of flying personnel (FP) faces a high risk to develop MS, due to the specific workload of specialized aircrew, the consequences for aeromedical screening are to be reconsidered. METHODS: Data of the complete military flying personnel (MFP) of Germany were screened to develop MS-related risk factors, regular physical activity and determination of nicotin and alcohol consumption. A comparable screening of a population of German civilian flying personnel (CFP) was undertaken by questionnaire. Statistics were completed by comparison of averages by t-test for independent random-samples of different variances and testing of independence of single characteristics by chi2-test. RESULTS: Data of approximately 10,000 aircrew members were obtained. It was possible to determine a group of MFP with higher risk to develop MS later in life, called "possible future metabolics" (PFM). Comparison of PFM with the MFP control group (MCG) and CFP clearly showed that obesity, dyslipoproteinemia and hypertension are the main single and/or combined risk factors. As a new aspect, data of MFP showed possible connections between thyroideal dysfunction and the prevalence of relevant MS-risk factors. CONCLUSIONS: The purpose of this investigation was to determine the actual risk of MS in German FP and to confirm the current MS-related regular screening measures. This study revealed that German MFP and CFP show a high quality health status without significant differences between both groups. Continuing the current regular flight medical screening will prevent FP from losing its high quality health status.

Lung function requirements in flying duty the problem of bronchial hyperresponsiveness in military aircrew.

UNLABELLED: Uncompromised lung function is essential for fitness to fly. Under hypobaric conditions there is an increased risk of hypoxemia. G-forces, positive pressure breathing and anti-G maneuvers cause physical stress to the lung tissue and altered pulmonary blood flow. Breathing with pure oxygen, dry cabin air and ozone can cause airway irritation. Chemically and physically by irritating agents may be present. Emergencies such as smoke in the cockpit or inhalation of tear gas can rapidly compromise the pulmonary system in susceptible persons. Sudden incapacitation may occur. Trapped gases may cause overinflation and lung rupture in rapid decompression. Applicants for military duty have to pass basic lung function tests routinely. Preselection of aircrew candidates tends to be even stricter. Asthma and obstructive lung disease are disqualifying. Trained aircrew with late onset of pulmonary problems can be waived under certain restrictions in many cases. Some national regulations exclude even applicants with allergies. Due to aeromedical experience we should always be aware of the latent unspecific bronchial hyperresponsiveness (BHR). BHR is one of the characteristics of asthma bronchiale. If BHR exists there is an increased risk of later development of asthma bronchiale, especially together with perennial allergies such as against house dust mite. Under certain conditions BHR can become symptomatic and aeromedically relevant. In some cases we saw an exacerbation under medication, mostly under beta-receptor-blockers. In one case even under betablocker-containing eye drops. In the Gulf War 1991 a number of allied military personnel had to be withdrawn because of bronchospastic symptoms. This can be explained among others by medication with physostigmine. Physostigmine is a systemically active cholinergic drug which is prophylactically used under threat of chemically warfare agents. In individuals with latent BHR physostigmine will lower the threshold for bronchial reactions considerably and even cause manifest bronchospasm. CONCLUSIONS: We recommend an unspecific bronchial challenge test in the selection of personnel for duties where uncompromised lung function under all environmental conditions is essential.