The present study investigated cardiac function in hearts of mice with total deficiency of the β1-, β2- and β3-adrenoceptors (TKO) in comparison to wildtype mice (WT). We investigated cardiac morphology and echocardiographic function, measured protein expression of Ca2+-regulatory proteins, SERCA 2a activity, myofibrillar function, and performed running wheel tests. Heart weight and heart-to-body weight ratio were significantly smaller in TKO as compared to WT. This was accompanied by a decrease in the size of the cardiomyocytes in TKO. Heart rate and ejection fraction were significantly diminished in TKO as compared to WT. Protein expressions of SERCA 2a, ryanodine receptor and Na+/Ca2+-exchanger were similar in TKO and WT mice, but phospholamban protein expression was increased. PKAdependent phosphorylation of phospholamban at serine 16 was absent and CaMKII-dependent phosphorylation at threonine 17 was decreased in TKO. All alterations were paralleled by a decrease in SERCA 2a-activity. A similar maximal calciumdependent tension but an increased myofibrillar calciumsensitivity was measured in TKO as compared to WT. We did not observe relevant functional impairments of TKO in running wheel tests. In the absence of β-agonistic stimulation, SERCA 2a activity is mainly regulated by alterations of phospholamban expression and phosphorylation. The decreased SERCA 2a activity following β-adrenoceptor deficiency may be partly compensated by an increased myofibrillar calcium-sensitivity., S. Lee ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy
The protective role of nutrition factors such as calcium, vitamin D and vitamin K for the integrity of the skeleton is well understood. In addition, integrity of the skeleton is positively influenced by certain trace elements (e.g. zinc, copper, manganese, magnesium, iron, selenium, boron and fluoride) and negatively by others (lead, cadmium, cobalt). Deficiency or excess of these elements influence bone mass and bone quality in adulthood as well as in childhood and adolescence. However, some protective elements may become toxic under certain condition s, depending on dosage (serum concentration), duration of treatment and interactions among individual elements. We review the beneficial and toxic effects of key elements on bone homeostasis., I. Zofkova, M. Davis, J. Blahos., and Obsahuje bibliografii
Cardiovascular diseases are the most common cause of mortality and morbidity in most populations. As the traditional modifiable risk factors (smoking, hypertension, dyslipidemia, diabetes mellitus, and obesity) were defined decades ago, we decided to analyze recent data in patients who survived acute coronary syndrome (ACS). The Czech part of the study included data from 999 males, and compared them with the post-MONICA study (1,259 males, representing general population). The Lithuanian study included 479 male patients and 456 age-matched controls. The Kazakhstan part included 232 patients and 413 controls. In two countries, the most robust ACS risk factor was smoking (OR 3.85 in the Czech study and 5.76 in the Lithuanian study), followed by diabetes (OR 2.26 and 2.07) and hypertension (moderate risk elevation with OR 1.43 and 1.49). These factors did not influence the ACS risk in Kazakhstan. BMI had no significant effect on ACS and plasma cholesterol was surprisingly significantly lower (P<0.001) in patients than in controls in all countries (4.80 ±1.11 vs. 5.76 ±1.06 mmol /l in Czechs; 5.32 ±1.32 vs. 5.71 ±1.08 mmol /l in Lithuanians; 4.88 ±1.05 vs. 5.38±1.13 mmol /l in Kazakhs/Russians). Results from our study indicate substantial heterogeneity regarding major CVD risk factors in different populations with the exception of plasma total cholesterol which was inversely associated with ACS risk in all involved groups. These data reflect ethnical and geographical differences as well as changing pattern of cardiovascular risk profiles., J. A. Hubacek, V. Stanek, M. Gebauerova, V. Adamkova, V. Lesauskaite, D. Zaliaduonyte-Peksiene, A. Tamosiunas, A. Supiyev, A. Kossumov, A. Zhumadilova, J. Pitha., and Obsahuje bibliografii
Decades of liver regeneration studies still left the termination phase least elucidated. However regeneration ending mechanisms are clinicaly relevant. We aimed to analyse the timing and transcriptional control of the latest phase of liver regeneration, both controversial. Male Wistar rats were subjected to 2/3 partial hepatectomy with recovery lasting from 1 to 14 days. Time-series microarray data were assessed by innovative combination of hierarchical clustering and principal component analysis and validated by real-time RT-PCR. Hierarchical clustering and principal component analysis in agreement distinguished three temporal phases of liver regeneration. We found 359 genes specifically altered during late phase regeneration. Gene enrichment analysis and manual review of microarray data suggested five pathways worth further study: PPAR signalling pathway; lipid metabolism; complement, coagulation and fibrinolytic cascades; ECM remodelling and xenobiotic biotransformation. Microarray findings pertinent for termination phase were substantiated by real-time RT-PCR. In conclusion, transcriptional profiling mapped late phase of liver regeneration beyond 5th day of recovery and revealed 5 pathways specifically acting at this time. Inclusion of longer post-surgery intervals brought improved coverage of regeneration time dynamics and is advisable for further works. Investigation into the workings of suggested pathways might prove helpful in preventing and managing liver tumours., D. Rychtrmoc, ... [et al.]., and Obsahuje seznam literatury
In order to obtain basic information on the transport properties of differentiating embryonic nephrons, we examined the 7-day-old chick mesonephros by measuring the transtubular epithelial potential difference (TPD) and by histochemical detection of Na,K-ATPase activity. TPD as an indicator of the electrogenic transport was measured in individual segments of superficial nephrons in vivo. Their electric polarity was always lumen-negative. TPD was reduced by addition of 10 mM KCN applied to the mesonephric nephrons from the outside. In the proximal tubules, TPD was significantly lower (mean±SD: -1.0±0.5 mV) than in the distal and collecting tubules (-2.2±1.0 mV, pŁ0.05). Activity of the sodium pump was evaluated histochemically by detection of ouabain-sensitive potassium-dependent p-nitrophenyl phosphatase in cryostat sections of the mesonephros. The enzyme activity was demonstrated only in distal tubules and in the collecting ducts, but not in the proximal tubules. These findings have revealed significant differences between embryonic nephron segments: the distal tubule, in contrast to the proximal one, is supplied by the sodium pump and is able to generate higher TPD. Therefore, we consider that it is only the distal nephron, which possesses the ability of active transport., Z. Zemanová, E. Ujec., and Obsahuje bibliografii
Spontaneously hypertensive rats (SHR/NIH strain) harbor a deletion variant in the Cd36 fatty acid transporter and display defective fatty acid metabolism, insulin resistance and hypertension. Transgenic rescue of Cd36 in SHR ameliorates insulin resistance and improves dyslipidemia. However, the role of Cd36 in blood pressure regulation remains controversial due to inconsistent blood pressure effects that were observed with transgenic expression of Cd36 on the SHR background. In the current studies, we developed two new SHR transgenic lines, which express wild type Cd36 under the control of the universal Ef-1 promoter, and examined the effects of transgenic expression of wild type Cd36 on selected metabolic and cardiovascular phenotypes. Transgenic expression of Cd36 in the new lines was associated with significantly decreased serum fatty acids, amelioration of insulin resistance and glucose intolerance but failed to induce any consistent changes in blood pressure as measured by radiotelemetry. The current findings confirm the genetic association of defective Cd36 with disordered insulin action and fatty acid metabolism in the SHR/NIH strain and suggest that Cd36 is linked to other gene(s) on rat chromosome 4 that regulate blood pressure., M. Pravenec, V. Landa, V. Zídek, A. Musilová, L. Kazdová, N. Qi, J. Wang, E. St.Lezin, T. W. Kurtz., and Obsahuje bibliografii
Lecithin:retinol acyltransferase (LRAT) is the major enzyme responsible for retinol esterification in the mammalian body. LRAT exhibits specific activity in the cells with active retinol metabolism where it converts retinols into retinyl esters, which represents the major storage form of retinol. Besides hepatic stellate cells in the liver, LRAT appears to have a key physiologic role in several other tissues. In this study, we generated a transgenic reporter mouse expressing green fluorescence protein (EGFP) under the control of region containing -1166 bps from promoter upstream from the putative transcriptional start site and 262 bps downstream of this start. Transgenic reporter mice exhibited specific expression in eyes and testes. In eyes, expression of EGFP-reporter is found in lens and lens epithelium and fibers from embryo to adulthood. In testes, LRAT-EGFP reporter is expressed both in Sertoli and in spermatocytes marking initiation of spermatogenesis in prepubertal mice. Our data show that the examined LRAT regulatory region is sufficient to achieve strong and selective expression in the eye and testes but not in liver and other organs., D. Prukova, Z. Ileninova, B. Antosova, P. Kasparek, M. Gregor, R. Sedlacek., and Obsahuje bibliografii
Repeated postnatal caffeine treatment of rat pups led to transient developmental changes in cortical epileptic afterdischarges. To know if physiological cortical functions are also affected transcallosal evoked potentials were studied. Rat pups of the Wistar strain were injected daily with caffeine (10 or 20 mg/kg s.c.) from postnatal day (P) 7 to P11, control siblings received saline. Cortical interhemispheric responses were tested at P12, 18, 25 and in young adult rats. Amplitude of initial monosynaptic components was evaluated in averaged responses. Single pulses as well as paired and frequency (five pulses) stimulations were used. Developmental rules - highest amplitude of responses in 25-day-old rats, potentiation with paired and frequency stimulation present since P18 - were confirmed. Caffeine-treated rats exhibited transient changes: single responses were augmented in P25 if high stimulation intensity was used, paired-pulse and freque ncy responses were higher in experimental than in control anim als at P12, the opposite change was observed in 18- and more ma rkedly in 25-day-old rats. No significant changes were found in adult animals, monosynaptic transcallosal responses represent a simple and robust system. The developmental profile of described changes did not exactly correspond to changes in epileptic afterdischarges supporting the possibility that afterdischarges did not arise from early monosynaptic components of responses. In spite of transient nature of changes they can reflect delayed or more probably modified brain development., J. Tchekalarova, H. Kubová, P. Mareš., and Obsahuje bibliografii a bibliografické odkazy
The novel environment of a metabolic cage can be stressful for rodents, but few studies have attempted to quantify this stress-response. Therefore, we determined the effects on mean arterial pressure (MAP) and heart rate (HR), of placing mice of both sexes in metabolism cages for 2 days. After surgical implantation of a carotid artery catheter mice recovered individually in standard cages for 5 days. Mice then spent 2 days in metabolism cages. MAP and HR were monitored in the standard cage on Day 5 and in metabolism cages on Days 6-7. MAP increased by 18±3 and 22±4 %, while HR increased by 27±4 and 27±6 %, in males and females, respectively, during the first hours after cage switch. MAP decreased to baseline in the fourth and eighth h following metabolism cage switch in males and females, respectively. However, HR remained significantly elevated in both sexes during the entire two-day period in metabolism cages. Females had lower MAP than males both pre- and post- metabolism cage switch, but there were no sex differences in HR. These results demonstrate sustained changes in cardiovascular function when mice are housed in metabolism cages, which could potentially affect renal function., C. C. Hoppe ... [et al.]., and Obsahuje seznam literatury
Protein kinase C (PKC) appears to play a significant role in the signal transduction of cardiac growth and development. The aim of this study was to determine changes in the total PKC activity and the expression of PKC isoforms α, δ and ε in the rat heart that was affected by pressure overload imposed at postnatal day (d) 2. Three groups of Wistar rats were employed for the experiment: rats submitted to the abdominal aortic constriction (AC), sham-operated controls (SO) and intact controls. Animals were sacrificed at d2, d3, d5 and d10. The total PKC activity was measured by the incorporation of 32P into histone IIIS and the expression of PKC was analyzed by immunoblotting in the homogenate of the left ventricular myocardium and in the cytosolic, membrane-enriched (105 × g) and nuclear-cytoskeletalmyofilament- enriched (103 × g) fractions. We observed the significant transient increase in both the total PKC activity and the expression of all isoforms at d5 (the 3rd day after the operation) in the cardiac homogenate of AC rats as compared with SO animals. Aortic constriction did not significantly affect the distribution of activity and isoform abundance among individual cellular fractions except for PKCδ, which increased significantly at d10 in the cytosolic fraction at the expense of the membraneenriched fraction. It is concluded that PKCα, PKCδ and PKCε undergo transient upregulation associated with the accelerated cardiac growth induced by pressure overload imposed in the very early postnatal period., B. Hamplová ... [et al.]., and Obsahuje bibliografii a bibliografické odkazy