Association of Circulating Extracellular Matrix Components with Central Hemodynamics and Arterial Distensibility of Peripheral Arteries.

BACKGROUND: In addition to neuronal and endothelial regulators of vascular tone, the passive mechanical properties of arteries, determined by the molecular structure of extracellular matrices, are the principle modulators of vascular distensibility. Specifically, the association between collagen type IV (Col IV), a constituent of basement membrane, and arterial compliance remains unclear. METHODS: In 31 healthy adult men, radial applanation tonometry and pulse wave analysis were used to assess aortic augmentation index (AIx), aortic-to-radial pulse pressure amplification (PPAmpl), and time to reflection wave. RESULTS: Plasma Col IV and tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) concentrations were correlated with AIx (r = 0.51, p = 0.021 and r = -0.45, p = 0.042, respectively) after adjustment for age and heart rate (HR). Greater matrix metalloproteinase-9 (MMP-9) and TIMP-1 levels were associated with high PPAmpl (r = 0.45 and r = 0.64, respectively) and hence with compliant arteries. Multiple regression analyses revealed that 99% of the variation in PPAmpl was attributable to age, HR, Col IV, TIMP-1, and Col × TIMP-1 interaction (p < 0.001). No relations between tonometric variables and levels of MMP-1, -2, and -3; TIMP-2 and -4; fibronectin; glycosaminoglycans; and hydroxyproline were found. CONCLUSION: High circulating Col IV level indexes were associated with stiffer peripheral arteries whereas increased MMP-9 and TIMP-1 concentrations were associated with more compliant ones.

Cardiorespiratory Coordination in Hypercapnic Test Before and After High-Altitude Expedition.

Coordination of cardiovascular and respiratory systems enables a wide range of human adaptation and depends upon the functional state of an individual organism. Hypoxia is known to elicit changes in oxygen and carbon dioxide sensitivity, while training alters cardiorespiratory coordination (CRC). The delayed effect of high altitude (HA) acclimatization on CRC in mountaineers remains unknown. The objective of this study was to compare CRC in acute hypercapnia in mountaineers before and after a HA expedition. Nine trained male mountaineers were investigated at sea level before (Pre-HA) and after a 20-day sojourn at altitudes of 4,000-7,000 m (Post-HA) in three states (Baseline, Hypercapnic Rebreathing, and Recovery). A principal component (PC) analysis was performed to evaluate the CRC. The number of mountaineers with one PC increased Post-HA (nine out of nine), compared to Pre-HA (five out of nine) [Chi-square (df = 1) = 5.14, P = 0.023]; the percentage of total variance explained by PC1 increased [Pre-HA median 65.6 (Q1 64.9/Q3 74.9), Post-HA 75.6 (73.3/77.9), P = 0.028]. Post-HA, the loadings of the expired fraction of O2, CO2, and ventilation onto PC1 did not change, and the loading of heart rate increased [Pre-HA 0.64 (0.45/0.68) and Post-HA 0.76 (0.65/0.82), P = 0.038]. During the Recovery, the percentage of total variance explained by PC1 was higher than during the Baseline. Post-HA, there was a high correlation between the Exercise addiction scores and the eigenvalues of PC1 (r = 0.9, P = 0.001). Thus, acute hypercapnic exposure reveals the Post-HA increase in cardiorespiratory coordination, which is highly related to the level of exercise addiction.

Effect of Acute Hypoxia on Cardiorespiratory Coherence in Male Runners.

Understanding the mechanisms of oxygen supply regulation, which involves the respiratory and cardiovascular systems, during human adaptation to intense physical activity, accompanied by hypoxemia, is important for the management of a training process. The objectives of this study were to investigate the cardiorespiratory coherence (CRC) changes in the low-frequency band in response to hypoxic exposure and to verify a dependence of these changes upon sports qualification level in athletes. Twenty male runners aged 17-25 years were exposed to acute normobaric hypoxia (10% O2) for 10 min. Respiration, gas exchange, and heart rate were measured at baseline, during hypoxia, and after the exposure. To evaluate cardiorespiratory coupling, squared coherence was calculated based on 5-s averaged time series of heart and respiratory rhythms. Based on sports qualification level achieved over 4 years after the experimental testing, athletes were retrospectively divided into two groups, one high level (HLG, n = 10) and the other middle level (MLG, n = 10). No differences in anthropometric traits were observed between the groups. In the pooled group, acute hypoxia significantly increased CRC at frequencies 0.030-0.045 Hz and 0.075 Hz. In response to hypoxia, oxygen consumption decreased in HLG, and carbon dioxide production and ventilation increased in MLG. At 0.070-0.080 Hz frequencies in hypoxia, the CRC in HLG was higher than in MLG. Thus, highly qualified athletes enhance intersystem integration in response to hypoxia. This finding can be a physiological sign for the prognosis of qualification level in runners.

A quantitative method for estimating the adaptedness in a physiological study.

BACKGROUND: Existed mathematical models of individual adaptation are mostly reductionist by nature. Researchers usually a priori consider the subject adapted basing only on the fact of continued or prolonged influence of the harmful factor. This paper describes a method that allows assessing the physiological adaptedness to experimental challenges on the basis of holistic approach and quantitative criteria. METHODS: The suggested method comprises simple equations and incorporates into the model an indicator that differentiates functions in regard to their significance for determining physiological adaptedness considered as an outcome of the adaptive process. RESULTS: The proposed empirical model affords the possibility of comparing subjects in respect to their resistance to several loads. Physiological parameters were differentiated with regard to their significance for assessing adaptedness. Two examples of animal adaptation to exercise after physical training and plant adaptogen administration are considered. CONCLUSION: The calculated index of adaptedness is useful in that it replaces wordy descriptions of large tables that reveal alterations in numerous parameters of many subjects under study.

Associations of Del 301-303 alpha2B-adrenoceptor gene polymorphism with central hemodynamic parameters in the northern Russian population.

The ADRA2B gene 301-303 I/D polymorphism is associated with various cardiovascular phenotypes. However, an association of genotypes with the timing structure of cardiac cycle remains unclear. The central hemodynamic parameters were assessed by pulse wave analysis in 63 residents of the Kola Peninsula (68 N) aged 27-65 yr. The genotypes were determined by PCR. The paired comparisons revealed that II genotype carriers had higher values of augmentation index ( P = 0.014), ejection duration ( P = 0.045), and lower SEVR ( P = 0.035) than DD homozygotes. Multiple regression analysis adjusted for age, body mass index, heart rate, and blood pressure confirmed these results. Further sex stratified analysis showed that the associations existed only in men ( n = 33) whereas in women ( n = 30) the differences were suggestive ( P < 0.1). It is concluded that in a northern Russian population men carrying I allele have stiffer arteries, shorter diastole duration, and impaired coronary perfusion and seem to be at higher risk for cardiovascular diseases than DD carriers.

Seasonal inconstancy of human sex ratio at birth.

A large body of literature describes relationships between the sex ratio at birth and modifying factors. The relationships that display seasonal fluctuations are hypothesized to reflect causal impact of periconceptional and later intrauterine effects. This short review summarizes the results of studies that investigated internal and external influences on the seasonal pattern of human sex ratio at birth.

Limb muscle hemodynamics and arterial distensibility depend on atmospheric pressure in hypertensive men.

OBJECTIVE: To verify whether peripheral blood circulation and arterial wall distensibility are influenced by atmospheric pressure (AtPr) and to examine if their association is dependent on age and/or sex. METHODS: Associations among natural AtPr levels (on the examination day as well as 1 and 2 days prior), limb muscle hemodynamics, and distensibility of conduit arteries were retrospectively examined in an observational study of 276 untreated patients with primary moderate hypertension (mean age 56.4 years, 194 men). Forearm and calf circulations at rest and 3 min after ischemia were measured by venous occlusion plethysmography. Compliance of the brachial and shank arteries was assessed by oscillometry. RESULTS: After adjustment for age, degree of hypertension, and season, correlation and multiple regression analyses revealed a season-independent but age-dependent direct correlation between the stiffness of limb arteries and AtPr levels on the examination day in men, but not women. The association weakened with the degree of hypertension, disappeared with age, and was more evident in the arms than in the legs. CONCLUSION: Parameters of arterial wall distensibility in adult hypertensive men are susceptible to AtPr changes within the usually observed limits (730-770 mmHg). It is proposed that reduction of arterial wall barometric responsiveness in women and aging men is a likely mechanism underlying their meteosensitivity.

Reduced solar activity favors twin maternities.

Mechanisms underlying effects of physical factors on twin births are unclear. The present work studied an association between monthly and yearly multiple birth rates (MBRs) in the Novosibirsk region, south-west Siberia, in relation to solar activity (sunspot numbers) and geomagnetic activity (Ap index) from 1957 to 2008. The difference was verified by comparing the yearly MBR observed in 3-year peaks (M = 7.36, SD = 0.33 per 1,000 births) and 3-year troughs (M = 8.10, SD = 0.31 per 1,000 births, p < .001) of an 11-year solar cycle. An inverse correlation (r = -.60, p < .001) was found between sunspot numbers and MBR for a lag of 1 year. Cross-spectral analysis of a 52-year time series established a common signal with the period of 10.5 years, as well as high coherence (K(2) = 0.87). The multiple regression analysis revealed a significant interaction of solar and geomagnetic effects upon the frequency of twin maternities. The results show that elevated solar activity within the 11-year cycle coinciding with the time of conception inhibits multiple births in a manner depending on geomagnetic activity. It is hypothesized that the likely mechanism underlying the association is early fetal loss induced by solar radiation/flux and its terrestrial mediators.

Seasonality bias in adverse pregnancy outcomes in Siberia.

OBJECTIVE: To examine which months are unfavourable for conception in the region with the severe continental climate. DESIGN: Retrospective population based study. METHODS: Monthly data on incidence rate for gestose, maternal anaemia, pyelonephritis, threat to spontaneous abortion, stillbirth, perinatal death and infant death at age under one year were extracted from medical records of obstetric, delivery, and paediatric hospitals in Novosibirsk (1976-1980), Norilsk (Taimir peninsula), and Mirny (western Yakutia). Two latter towns were considered together as a northern setting. Edwards' method was applied to test seasonality. RESULTS: In Novosibirsk as well as in northern towns, the monthly distribution of time of conception for preterm births, maternal pyelonephritis, and infant deaths displays significant seasonal pattern with maximum in summer. Additionally in the North, stillbirths' conceptions also tended to be concentrated in June. CONCLUSION: In Siberia, the polar day and summer months are an unfavourable time for conceiving in respect to obstetric complications and adverse pregnancy outcomes.

Life span of people who died from cardiovascular diseases in Siberia: a comparative study of two populations.

OBJECTIVES: To assess associations between mean age at death from cardiovascular disease (myocardial infarction, acute heart failure, ischemic heart disease and stroke) and sex, education, socio-professional status, marital status, region of residence at birth, month and season of birth and of death in dependence of climatic conditions. DESIGN: A retrospective analysis of death certificates in two Siberian cities from 1971 to 1978 (Novosibirsk, south-western Siberia) and from 1968 to 1985 (Mirny, western Yakutia). METHODS: Analysis of variance, test for seasonality. RESULTS: A remarkable effect of birthplace on longevity was observed in Novosibirsk. West Russia-born decedents were older than their cause-of-death-matched counterparts born in Siberia. In this city, men died at younger age in spring months compared to the rest of the year. In Mirny, an extreme northern town with a very harsh climate, the life span depended on the duration of living in this region prior to death. CONCLUSION: There was some difference among cardiovascular diagnoses and between the two cities. However, overall, the results offer some support for theories suggesting that early "imprinting" is responsible for the association between life span and region/season of birth.