To determine the role of postinspiratory inspiratory activity of the diaphragm in the biphasic ventilatory response to hypoxia in unanesthetized rats, we examined diaphragmatic activity at its peak (DI), at the end of expiration (DE), and ventilation in adult unanesthetized rats during poikilocapnic hypoxia (10 % O2) sustained for 20 min. Hypoxia induced an initial increase in ventilation followed by a consistent decline. Tidal volume (VT), frequency of breathing (fR), DI and DE at first increased, then VT and DE decreased, while fR and DI remained enhanced. Phasic activation of the diaphragm (DI - DE) increased significantly at 10, 15 and 20 min of hypoxia. These results indicate that 1) the ventilatory response of unanesthetized rats to sustained hypoxia has a typical biphasic character and 2) the increased end-expiratory activity of the diaphragm limits its phasic inspiratory activation, but this increase cannot explain the secondary decline in tidal volume and ventilation., H. Maxová, M. Vízek., and Obsahuje bibliografii
Cardiac resynchronization therapy is not commonly used in the early postoperative period in pati ents undergoing cardiac surgery who have left ventricular (LV) dysfunction and a history of heart failure. We performed a prospective randomized clinical trial to compare atrial synchronous right ventricular (DDD RV) and biventricular (DDD BIV) pacing within 72 hours after cardiac surgery in patients with an EF ≤ 35 %, a QRS interval longer than 120 msec and who had LV dyssynchrony detected by real-time three-dimensional echocardiography (RT3DE). Epicardial pacing was provided by a modified Medtronic INSYNC III pacemaker. An LV epicardial pacing lead was implanted on the latest activated segment of the LV based on RT3DE. The study included 18 patients with ischemic heart diseas e, with or without valvular heart disease (14 men, 4 women, average age 71 years). Patients undergoing DDD BIV pacing had a statistically significant greater CO and CI (CO 6.7±1.8 l/min, CI 3.4±0.7 l/min/m²) than patients undergoing DDD RV pacing (CO 5.5±1.4 l/min, CI 2.8±0.7 l/min/m²), p<0.001. DDD BIV paci ng in the early postoperative period after cardiac surgery corrects LV dyssynchrony and has better hemodynamic results than DDD RV pacing., F. Straka ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
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
The gold standard material in bypass surgery of blood vessels remains the patient’s own artery or vein. However, this material may be unavailable, or may suffer vein graft disease. Currently available vascular prostheses, namely polyethylene terephthalate (PET, Dacron) and expanded poly tetrafluoroethylene (ePTFE), perform well as large-caliber replacements, but their long-term patency is discouraging in small-caliber applications (<6 mm), such as in coronary, crural or microvessel surgery. This failure is mainly a result of an unfavorable healing process with surface thrombogenicity, due to lack of endothelial cells and anastomotic intimal hyperplasia caused by hemodynamic disturbances. An ideal small-diameter vascular graft has become a major focus of research. Novel biomaterials have been manufactured, and tissue-biomaterial interactions have been optimized. Tissue engineering technology has proven that the concept of partially or totally living blood vessels is feasible. The purpose of this review is to outline the vascular graft materials that are currently being implanted, taking into account cell-biomaterial physiology, tissue engineering approaches and the collective achievements of the authors., J. Chlupáč, E. Filová, L. Bačáková., and Obsahuje seznam literatury
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
This minireview briefly surveys the complexity of regulations governing the bone metabolism. The impact of clinical studies devoted to osteoporosis is briefly summarized and the emphasis is put on the significance of experimental mouse models based on an extensive use of genetically modified animals. Despite possible arising drawbacks, the studies in mice are of prime importance for expanding our knowledge on bone metabolism. With respect to human physiology and medicine, one should be always aware of possib le limitations as the experimental results may not be, or may be only to some extent, transposed to humans. If applicable to humans, results obtained in mice provide new clues for assessing un foreseen treatment strategies for patients. A recent publication representing in our opinion the important breakthrough in the field of bone metabolism in mice is commented in detail. It provides an evidence that skeleton is endocrine organ that affects energy metabolism and osteocalcin, a protein specifically synthesized and secreted by osteoblasts, is a hormone involved. If confirmed by other groups and applicable to humans, this study provides the awaited connection of long duration between bone disorders on one hand and obesity and diabetes on the other., O. Raška, K. Bernášková, I. Raška Jr., and Obsahuje seznam literatury
The aim of the study was to compare the bone mineral density (BMD) and body composition between ambulatory male MS patients and control subjects and to evaluate the relationships among body composition, motor disability, glucocorticoids (GC) use, and bone health. Body composition and BMD were measured by dual-energy X-ray absorptiometry in 104 ambulatory men with MS (mean age: 45.2 years) chronically treated with low-dose GC and in 54 healthy age-matched men. Compared to age-matched controls, MS patients had a significantly lower total body bone mineral content (TBBMC) and BMD at all measured sites except for the radius. Sixty five male MS patients (62.5 %) met the criteria for osteopenia and twenty six of them (25 %) for osteoporosis. The multivariate analysis showed a consistent dependence of bone measures (except whole body BMD) on BMI. The total leg lean mass % was as an independent predictor of TBBMC. The Expanded Disability Status Scale (EDSS), cumulative GC dose and age were independent determinants for BMD of the proximal femur. We conclude that decreasing mobility in male MS patients is associated with an increasing degree of osteoporosis and muscle wasting in the lower extremities. The chronic low-dose GC treatment further contributes to bone loss., V. Zikán ... [et al.]., and Obsahuje seznam literatury
The peak bone mass and the rate of bone loss are in part genetically determined. It has been suggested that bone mineral density (BMD) may be related to allelic variation in the apolipoprotein E (ApoE) gene locus. ApoE is important in the receptor-mediated clearance of chylomicron particles from the plasma, Apo E4 having the highest and Apo E2 the lowest receptor affinity. Chylomicrons are the main carrier of vitamin K in the plasma; vitamin K plays an important role in the carboxylation of osteocalcin. We have tested the hypothesis that persons with E4 variant would have lower BMD and increased bone turnover than those with E2 variant. A total of 18 ApoE 2/2 and ApoE 4/4 homozygotes were selected from 873 patients who were examined for the ApoE genotype. BMD in lumbar vertebral, femoral neck and distal forearm was measured and plasma concentrations of osteocalcin and C-terminal fragments of collagen (CTx) were determined. BMD values (expressed as T-score) at the three specified sites were -0.12± 1.72, -0.52± 1.32 and -0.52± 0.81 in ApoE 2/2 group and -0.24± 1.22, 0.00± 0.84 and -0.17± 1.07 in the ApoE 4/4 group. Plasma osteocalcin and CTx were within normal limits in both groups. In conclusion, we did not observe any association of ApoE genotype with BMD and biochemical markers of bone metabolism in ApoE 2/2 and ApoE 4/4 homozygotes., T. Štulc, R. Češka, A. Hořínek, J. Štěpán., and Obsahuje bibliografii