Browsing by Author "Suzic, Slavica (57193378338)"

Aim: To determine whether complexity of chromatin structure in kidney macula densa cells (MDC) decreases during postnatal development in mice. Methods The levels of chromatin structural complexity were measured by determining fractal dimension of MDC nuclei. Kidney tissue was obtained from the total of 32 male Swiss albino mice divided into four age groups (n = 8): newborn (0 days), 10 days old, 20 days old and 30 days old. For a total of 640 MDC chromatin structures, fractal dimension, lacunarity, as well as parameters of Grey level co-occurrence matrix (GLCM) texture were determined. Results: Chromatin fractal dimension in animals aged 10 days, 20 days and 30 days was significantly lower (P < 0.05, P < 0.01 and P < 0.001, respectively), compared with newborn mice. This complexity reduction of chromatin architecture is in accordance with previously published studies, which detected generalized and sustained loss of both tissue and cell complexity during aging. The loss of complexity was texture-independent, since there was no statistically significant difference (P > 0.05) in both chromatin angular second moment and inverse difference moment between the age groups. Conclusion: Our results indicate that age-related nuclear intrinsic factors which do not influence chromatin texture may have an important role in MDC postnatal development. © 2012 The Authors. Nephrology © 2012 Asian Pacific Society of Nephrology.

There is compelling evidence that postexercise heart rate recovery (HRR) is a valid indicator of sympaticovagal balance. It is also used in prescription and monitoring of athletic training. The purpose of our study was to determine HRR after maximal exercise among elite athletes with respect to age. A total of 274 elite male Caucasian athletes were randomly selected from the larger sample and divided into two groups: adolescent (group Y) and adult athletes (≥18 years; group A). They performed maximal cardiopulmonary exercise testing on a treadmill. Heart rate recovery was calculated as the rate of decline of HR from peak exercise to rates 1, 2 and 3 min after cessation of exercise (HRR1, HRR2 and HRR3). A significantly higher HRR1 was found in group A (29·5 ± 15·6 versus 22·4 ± 10·8, P<0·001), but HRR3 was higher in group Y (82·7 ± 10·2 versus 79·9 ± 12·25; P = 0·04). Stepwise multivariate linear regression analysis showed that, among all subjects, the HRR1 alone was independently associated with age (P<0·001). The maximal oxygen consumption (VO2 max) was in a negative relationship with HRR1 and in a positive one with HRR3 (P<0·05) with respect to all athletes. The HRR during 3 min postexercise should be reported for the purpose of better assessing functional adaptation to exercise among elite athletes as well as the age-associated differences in recovery. Higher values of HRR1 should be expected in older athletes, and HRR3 could be used as an index of aerobic capacity, irrespective of age. © 2015 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd

There is compelling evidence that postexercise heart rate recovery (HRR) is a valid indicator of sympaticovagal balance. It is also used in prescription and monitoring of athletic training. The purpose of our study was to determine HRR after maximal exercise among elite athletes with respect to age. A total of 274 elite male Caucasian athletes were randomly selected from the larger sample and divided into two groups: adolescent (group Y) and adult athletes (≥18 years; group A). They performed maximal cardiopulmonary exercise testing on a treadmill. Heart rate recovery was calculated as the rate of decline of HR from peak exercise to rates 1, 2 and 3 min after cessation of exercise (HRR1, HRR2 and HRR3). A significantly higher HRR1 was found in group A (29·5 ± 15·6 versus 22·4 ± 10·8, P<0·001), but HRR3 was higher in group Y (82·7 ± 10·2 versus 79·9 ± 12·25; P = 0·04). Stepwise multivariate linear regression analysis showed that, among all subjects, the HRR1 alone was independently associated with age (P<0·001). The maximal oxygen consumption (VO2 max) was in a negative relationship with HRR1 and in a positive one with HRR3 (P<0·05) with respect to all athletes. The HRR during 3 min postexercise should be reported for the purpose of better assessing functional adaptation to exercise among elite athletes as well as the age-associated differences in recovery. Higher values of HRR1 should be expected in older athletes, and HRR3 could be used as an index of aerobic capacity, irrespective of age. © 2015 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd

Objectives: Hypertension is one of the most prevalent cardiovascular disorders in athletes. The aims of our study were to assess the impact of elevated blood pressure (BP) on exercise capacity in athletes and evaluate the differences in left ventricular structure and function. Methods: Elite male athletes (n = 517, aged 23 ± 5 years) underwent Doppler echocardiography with tissue Doppler imaging. Diastolic function was assessed by measuring peak early and late transmitral (E and A) and annular diastolic filling velocities (e′ and a′). Maximal cardiopulmonary exercise testing was performed to measure maximal oxygen consumption (VO2max), ventilatory anaerobic threshold (VAT) and heart rate reserve (HRR). After BP measurement, they were grouped according to the ESH/ESC guidelines on: optimal (OBP), normal (NBP), high normal BP (HNBP), and hypertensive (HT). Results: We found significantly lower VO2max, VAT and HRR in the groups with HNBP and HT, after the adjustment for the type of sport, body fat content and age. There was an increasing trend in resting HR among groups (p < 0.001). Although none of the subjects had impaired diastolic function, the HT group had higher left atrial volume, and lower e′ and e′/a′. Resting systolic BP (p < 0.05), HR (p < 0.001), HRR (p < 0.001) and e′/a′ (p < 0.01) independently predicted VO2max. Indexes E/e′ and e′/a′ were associated with resting systolic BP (p < 0.05). Conclusion: Even in the absence of structural or functional heart damage, elevated BP in elite athletes, together with the presence of autonomic dysfunction, leads to decrease in exercise capacity. Staging of hypertension according to the BP level, on the one hand, and reflexion of BP on cardiopulmonary capacity, on the other, may be coupled for further risk stratification. © 2014 Elsevier Ireland Ltd. All rights reserved.