An improved design of optical sensor for long-term measurement of arterial blood flow waveform.

We present here the improved design and development of optical sensor for non-invasive measurements of arterial blood flow waveform. The sensor is based on a physical principle of reflective photoplethysmography (PPG). As the light source we used serially connected infrared diodes whereas NPN silicon phototransistors were used as light detectors. The electronic components were molded into square package and poured with silicone. Such preparation produced an elastic superficies that allowed excellent attachment of the sensor on the skin's surface. Moreover, a serial connection of infrared diodes and phototransistors completely eliminated signal artifacts caused by minor muscle contractions. The sensor recording performances were examined at the photoplethysmographic sites on three different arteries; the commune carotid, femoral and radial and, on each site the sensor demonstrated remarkable capability to make a consistent, reproducible measurements. Because of the advantageous physical and electrical properties, the new sensor is suitable for various cardiovascular diagnostics procedures, especially when long-term measurements of arterial blood flow waveform are required, for monitoring of different parameters in cardiovascular units and for research.

Complexity reduction of chromatin architecture in macula densa cells during mouse postnatal development.

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.

Serum and erythrocyte membrane phospholipids fatty acid composition in hyperlipidemia: effects of dietary intervention and combined diet and fibrate therapy.

Hyperlipidemia is found to be associated with changes in fatty acid (FA) profiles. The aim of this study was to investigate the effects of AHA-Step-1 dietary treatment and combination of fibrates (gemfibrozil) with dietary intervention on serum and erythrocyte phospholipid FA composition in human hyperlipidemia. 78 study participants with hyperlipidemia were divided in two groups. In D group (n = 41) subjects followed AHA-Step-1 diet (<30% of total from fat, <10% of energy from saturated fat, and <300 mg cholesterol per day). D+F group (n = 37) followed Step-1 diet and were receiving gemfibrozil (300 mg/twice per day). Serum lipid levels and phospholipid serum and erythrocyte FA compositions were analyzed at the beginning and after 12 weeks of treatment. Alteration in serum and erythrocyte phospholipid FA profile were found in both groups. After both treatments we found significantly higher serum phospholipid percentages of n-3, n-6 and total polyunsaturated FA. Linoleic (LA, n-6) and docosahexaenoic acid (DHA, n-3) were higher in D group, but arachidonic (AA, n-6) and linolenic acid (LNA, n-3) in D+F group. In erythrocyte phospholipid levels of stearic, palmitoleic (16 : 1, n-7) and LA were significantly higher in D group, but palmitic acid, AA and eicosapentaenoic acid (EPA, n-3) in D+F group. Stronger correlation between serum triglycerides with EPA and DHA in erythrocyte membrane phospholipid was found in D+F group. Markedly increased percentage of AA in serum and erythrocyte membrane phospholipid in hyperlipidemic patients receiving gemfibrozil on Step-1 diet is especially important for physiological functions (inflammation, vascular tone, hemostasis etc.) in relation to cardiometabolic risk.

Overweight in trained subjects - are we looking at wrong numbers? (Body mass index compared with body fat percentage in estimating overweight in athletes.).

Body mass index (BMI) is widely used as an index of obesity in adults. In trained population, individual with low body fat could be classified as overweight by BMI. To evaluate this problem, the purposes of this study were to determine the BMI and body fat percentage (BF%) of trained and untrained subjects and to evaluate the accuracy of BMI classification (> or =25 kg.m(-2)) as a prediction of overweight/obesity in trained subjects. The total number of 299 trained (basketball players) and 179 untrained male subjects participated in this study. Body height and body mass were measured; BMI was calculated for all subjects. BF% was determined via Tanita bioimpedance body composition analyzer. BMI >or = 25 kg.m(-2) and BF% > 20% were used to define overweight. There was no significant age differences. Body mass, height (p < 0.01) and BMI (p < 0.05) were significantly higher, although BF% was significantly lower (p < 0.01) in trained group when compared to untrained. Eighty-five trained subjects had a BMI of 25 or higher, indicating overweight. Of these, only three individuls had excess BF%. The results of the present study suggest that a BMI > or = 25 kg.m(-2) is not an accurate predictor of overweight in trained subjects.

Heart rate recovery in elite athletes: the impact of age and exercise capacity.

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.

The impact of elevated blood pressure on exercise capacity in elite athletes.

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±5years) 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.