The production of the pineal hormone melatonin is synchronized with day-night cycle via multisynaptic pathway including suprachiasmatic nucleus linking several physiological functions to diurnal cycle. The recent data indicate that impaired melatonin production is involved in several cardiovascular pathologies including hypertension and ischemic heart disease. However, the mechanisms of melatonin effect on cardiovascular system are still not completely understood. The activation of melatonin receptors on endothelial and vascular smooth muscle cells and antioxidant properties of melatonin could be responsible for the melatonin effects on vascular tone. However, the data from in vitro studies are controversial making the explanation of the melatonin effect on blood pressure in vivo difficult. In vivo, melatonin also attenuates sympathetic tone by direct activation of melatonin receptors, scavenging free radicals or increasing NO availability in the central nervous system. The central and peripheral antiadrenergic action of chronic melatonin treatment might eliminate the mechanisms counter-regulating decreased blood pressure, providing thus additional cardioprotective mechanism. The extraordinary antioxidant activity and antilipidemic effects of melatonin may enhance the modulation of blood pressure by melatonin and probably play the most important role in the amelioration of target organ damage by chronic melatonin treatment. Further investigation of these mechanisms should provide novel knowledge about pathophysiological mechanisms of cardiovascular diseases, additional explanation for their circadian and seasonal variability and potentially generate new impulses for the development of therapeutic arsenal., Ľ. Paulis, F. Šimko., and Obsahuje bibliografii a bibliografické odkazy
Sympathetic activation and parasympathetic withdrawal are commonly observed during acute exacerbations of chronic obstructive pulmonary disease (COPD). We have demonstrated previously that noninvasive positive-pressure ventilation (NPPV) improves parasympathetic neural control of heart rate in patients with obstructive sleep apnea. We hypothesized that NPPV may exert such beneficial effects in COPD as well. Therefore, we assessed the acute effects of NPPV on systemic blood pressure and indexes of heart rate variability (HRV) in 23 patients with acute exacerbations of COPD. The measurements of HRV in the frequency domain were computed by an autoregressive spectral technique. The use of NPPV resulted in significant increases of oxygen saturation (from 89.2±1.0 to 92.4±0.9 %, p<0.001) in association with reductions in systolic and diastolic blood pressures and heart rate (from 147±3 to 138±3 mm Hg, from 86±2 to 81±2 mm Hg, from 85±3 to 75±2 bpm, p<0.001 for all variables), and increases in ln-transformed high frequency band of HRV (from 6.4±0.5 to 7.4±0.6 ms2/Hz, p<0.01). Reductions in heart rate and increases in ln-transformed HF band persisted after NP PV withdrawal. In conclusion, these findings suggest that NPPV may cause improvements in the neural control of heart rate in patients with acute exacerbations of COPD., P. Skyba, P. Joppa, M. Orolín, R. Tkáčová., and Obsahuje bibliografii a bibliografické odkazy
Variants within the FTO gene are important determinants of body mass index (BMI), but their role in determination of BMI changes after combined dietary/physical ac tivity intervention is unclear. We have analyzed 107 unrelated overweight non-diabetic Czech females (BMI over 27.5 kg/m2 , age 49.2±12.3 years). FTO variants rs17817449 (first intron) and rs17818902 (third intron) were genotyped. The life style mo dification program (10 weeks) consisted of an age- matched reduction of energy intake and exercise program (aerobic exercise 4 times a week, 60 min each). The mean BMI before intervention was 32.8±4.2 kg/m2 and the mean achieved weight loss was 4.8±3.5 kg (5.3±3.5 %, max. -15.5 kg, min. +2.0 kg, p<0. 01). No significant association between BMI decrease and FTO variants was found. Also waist-to-hip ratio, body composition (body fat, water, active tissue), lipid parameters (total, LDL and HDL cholesterol, triglycerides) glucose and hsCRP change s were independent on FTO variants. FTO variants rs17817449 and rs17818902 are not associated with BMI changes after combined short time dietary/physical activity intervention in overweight females., D. Dlouhá ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
In the present paper we describe changes of anatomical parameters in inbred Lewis strain rats, namely their body weight, body weight gain per week, absolute and relative heart, thyroid gland and skeletal muscle weights, that are assumed to reflect experimentally altered thyroid status. The hyperthyroid state was induced by DL-thyroxine or Na 3,3',5-triiodo-L-thyronine, while methimazole was employed for inducing hypothyroidism. We have found that when compared to euthyroid rats, hypothyroidism resulted in a significantly lower body weight gain, absolute and relative heart weight and, in contrast, in a significant increase of absolute and relative thyroid gland weight. On the other hand, hyperthyroidism led to a significant increase of absolute and relative heart weight and to a significant reduction of absolute and relative thyroid gland weight. However, the body mass was not significantly altered in hyperthyroidism as compared with euthyroid rats. We conclude that our protocol leads to chronic hyper- or hypothyroidism as demonstrated by body, heart and thyroid gland weight changes. These anatomical data can thus be utilized as supplemental criteria for the assessment of the thyroid state of experimental rats., T. Soukup, G. Zachařová, V. Smerdu, I. Jirmanová., and Obsahuje bibliografii