Biomedical subjects

O Krizanová

Publications and source records attributed to O Krizanová.

At least 19 recordsLinked to original sources

PubMed2006

Levels of myosin heavy chain mRNA transcripts and protein isoforms in the fast extensor digitorum longus muscle of 7-month-old rats with chronic thyroid status alterations.

We have studied the effect of chronic thyroid status alterations on the myosin heavy chain (MyHC) isoform composition (by SDS-PAGE) and on MyHC mRNA levels (by RT-PCR) in the fast extensor digitorum longus (EDL) muscle of 7-month-old inbred Lewis strain female rats and compared this with corresponding results of the previously studied slow soleus muscle. Our findings show that in the EDL muscle, all four types 1, 2a, 2x/d and 2b of MyHC mRNA transcripts and protein isoforms are present in euthyroid, hypothyroid and hyperthyroid rats, i.e. after chronic treatment with methimazole and T(3), respectively. This is in contrast with the soleus, where only MyHC1 and 2a protein isoforms are expressed under similar conditions. Except for 2x/d MyHC mRNA transcripts in the EDL muscles, there was always significant difference between hypothyroid and hyperthyroid rats both at mRNA and protein levels. From our results we can conclude that extended alteration of the thyroid status leads to typical changes in the expression of MyHC mRNA transcripts and MyHC protein isoforms in the fast EDL and the slow soleus muscles. These changes correspond to those described after shorter periods of altered thyroid status. The characteristic phenotype differences between soleus and EDL muscles remain, however, preserved even after 7 months of thyroid hormone status alteration.

Age Factors↗

PubMed2006

Levels of myosin heavy chain mRNA transcripts and content of protein isoforms in the slow soleus muscle of 7 month-old rats with altered thyroid status.

Skeletal muscles of small rodents contain four main fiber types, namely type 1, 2A, 2X/D and 2B fibers containing myosin heavy chain (MyHC) 1, 2a, 2x/d and 2b isoforms. Each of these MyHC isoforms is the product of a distinct gene and their expression is believed to be primarily transcriptionally controlled. In most rat muscles, messenger RNA (mRNA) transcripts for MyHC1, 2a, 2x/d and 2b and their corresponding protein products were found with the exception of the soleus muscle, where typically only MyHC1 and 2a transcripts and protein isoforms were demonstrated under normal conditions. Here we show the expression of all four MyHC1, 2a, 2x/d and 2b mRNA transcripts in the soleus muscle under normal conditions in euthyroid, as well as in experimental hypothyroid and hyperthyroid (with the exception of 2b MyHC transcript) 7-month-old female inbred Lewis rats. This is not matched, however, by the appearance of corresponding four isoforms, as we have found that 2x/d and 2b protein isoforms are not present at levels detectable by SDS-PAGE. We also show that the chronic hypothyroid and hyperthyroid status affects the expression of MyHC isoforms both at the mRNA and protein levels.

Animals↗

PubMed2005

Effect of neonatal streptozotocin and thyrotropin-releasing hormone treatments on insulin secretion in adult rats.

Neonatal STZ (nSTZ) treatment results in damage of pancreatic B-cells and in parallel depletion of insulin and TRH in the rat pancreas. The injury of B-cells is followed by spontaneous regeneration but dysregulation of the insulin response to glucose persists for the rest of life. Similar disturbance in insulin secretion was observed in mice with targeted TRH gene disruption. The aim of present study was to determine the role of the absence of pancreatic TRH during the perinatal period in the nSTZ model of impaired insulin secretion. Neonatal rats were injected with STZ (90 microg/g BW i.p.) and the effect of exogenous TRH (10 ng/g BW/day s.c. during the first week of life) on in vitro functions of pancreatic islets was studied at the age 12-14 weeks. RT-PCR was used for determination of prepro-TRH mRNA in isolated islets. Plasma was assayed for glucose and insulin, and isolated islets were used for determination of insulin release in vitro. The expression of prepro-TRH mRNA was only partially reduced in the islets of adult nSTZ rats when compared to controls. nSTZ rats had normal levels of plasma glucose and insulin but the islets of nSTZ rats failed to response by increased insulin secretion to stimulation with 16.7 mmol/l glucose or 50 mmol/l KCl. Perinatal TRH treatment enhanced basal insulin secretion in vitro in nSTZ animals of both sexes and partially restored the insulin response to glucose stimulation in nSTZ females.

Aging↗

PubMed2003

[Use of knock-out mice in studies of stress reactions].

Modern human population intimately recognizes the stress reaction of the organism, which has developed as a response to variety physical and/or psychical stressors. This reaction represents not only a complex of adaptive mechanisms enabling the successful overcoming of the conflicting situation, but in its pathological form it can significantly contribute to the development of serious diseases, from carcinogenic, cardiovascular, gastrointestinal, up to the psychical. New, developing scientific disciplines permit to widen knowledge of the basis of this undesirable side of the stress. Transgenic animals, which either has integrated the gene of interest, or studied gene is not functioning (i.e. knockout animals), permit at least partially to study the physiological importance of the product of this gene in the organism. In our review we described in detail three lines of knockout mice--with the knockout gene for the dopamine-beta-hydroxylase, corticoliberin and c-fos--that significantly contribute to the regulation of the stress response.

Animals↗

PubMed2002

New approach to human high-risk papillomavirus (HR-HPV) genotyping.

Human high-risk papillomaviruses (HR-HPVs) are involved in the induction of invasive cervical cancer. The aim of this study was to introduce a simple, semi-automated and reproducible approach suitable for HR-HPV detection in clinical practice. The procedure is based on DNA isolation, nested polymerase chain reaction, single strand conformational polymorphism and evaluation of HR-HPV genotypes with Gel-Pro software. The clinical performance of the new approach was assessed in two different patient materials: 1) cervical smears with cytological classification Pap2-3 or Pap3 lacking nuclear atypia (anisonucleosis and polychromasia) or koilocytotic atypia and without any previous therapy 2) formalin-fixed, paraffin-embedded cervical carcinoma and lymph node sections. Using the new approach we detected HR-HPV DNA in 64% patient samples cytologically classified as Pap2-3 or Pap3 respectively and in 80% formalin-fixed, paraffin-embedded lymph node sections histologically classified as lymph nodes without carcinoma cell infiltration. The combination of methods described in this study results in increased sensitivity of HR-HPV identification allowing detection of HPV DNA in a very small amount of target DNA so that it can be widely used in distinguishing the pre- malignant lesions and in determination of invading carcinoma cells to lymph nodes in patients with advanced cervical cancer. The new approach is useful in unambiguous HR-HPV genotyping even in double-HPV infection.

Automation↗

PubMed2002

[Catecholamine synthesis and expression of enzymes of the catecholamine pathway in the rat heart at rest and during stress].

Catecholamines participate in a variety of cell regulations and physiological mechanisms, but also in the development of neurological, psychiatrical, endocrine and cardiovascular diseases. Diseases of the cardiovascular system, such as hypertension, myocardial infarction, ischaemia, etc. represent a serious medical problem and a frequent cause of the human death. It is alarming that development of these diseases depends preferentially on the wrong life-style and affect lower age groups. One of the factors that participate on unwilling increase of the incidence of cardiovascular diseases is the stress. Under the stress, organism mobilizes its energetical sources, increases cardiac performance and activates other processes, which enable to handle this load. Catecholamines belong to the important mediators of the stress response. On the one side they are required to buffer the stress situation, but the pathological changes in the regulation of their synthesis, secretion and action significantly participate on the development of several diseases (e.g. also of the cardiovascular origin). The aim of this review is to show the role of catecholamines in the heart not only under the physiological, but also in pathophysiological conditions. Stress as a modern civilization factor participates on the development of several diseases. Understanding of the mechanism of development of these diseases is the first step to the development of an appropriate therapy. Changes in the catecholamine levels during stress, as well as enzymes, which participate on the synthesis of catecholamines, are undoubtedly the important part of this mechanism.

Animals↗

PubMed2001

Identification of tyrosine hydroxylase gene expression in rat spleen.

This study was aimed to identify tyrosine hydroxylase (TH) gene expression in the rat spleen under basal and stress conditions. Using the reverse transcription polymerase chain reaction we did not detect TH mRNA in rat spleen either in control, or immobilized animals. Semi-nested PCR revealed a clear signal, demonstrating that TH mRNA is formed in the spleen, although in low abundance. We also detected both, TH immunoreactive protein and TH activity in the rat spleen that were in higher abundance than expected from the mRNA levels. This study identifies, for the first time, TH gene expression in rat spleen. Since TH protein and activity are present in the spleen in much higher abundance compared to corresponding mRNA, the majority of TH protein is most probably supplied by the sympathetic innervation of spleen.

Animals↗

PubMed2001

Effect of nicotinic acid adenine dinucleotide phosphate on ryanodine calcium release channel in heart.

Nicotinic acid adenine dinucleotide phosphate (NAADP), a molecule derived from nicotinamide adenine dinucleotide phosphate (NADP+), is a recently identified nucleotide that activates Ca2+ release from intracellular stores in invertebrate eggs and in mammalian cells. NAADP could function as an intracellular messenger for mobilizing internal Ca2+ stores, however the targets and nature of NAADP-induced Ca2+ release are unknown. We report here that NAADP (3-10 microM) induces Ca2+ release from rat heart microsomes and that NAADP (1-10 microM) activates single ryanodine receptor/calcium release channels (RyR2) from dog heart incorporated into bilayer lipid membranes. The results indicate that NAADP may play a role in cardiac excitation-contraction coupling by acting on RyR2 channels.

Animals↗

PubMed2001

SB203580, a specific inhibitor of p38-MAPK pathway, is a new reversal agent of P-glycoprotein-mediated multidrug resistance.

P-glycoprotein (P-gp) is the plasma membrane transport pump responsible for efflux of chemotherapeutic agents from cells and is one of the systems that secures multidrug resistance (MDR) of neoplastic cells. In the present study, drug sensitive L1210 and multidrug resistant L1210/VCR (characterized by overexpression of P-gp) mouse leukemic cell lines were used as an experimental model. We have found that SB203580, a specific inhibitor of p38-MAPK pathway, significantly reduced the degree of the vincristine resistance in L1210/VCR cells. This phenomenon was accompanied by a decrease in the LC(50) value of vincristine from 3.203+/-0.521 to 0.557+/-0.082 microM. The LC(50) value of sensitive cells for vincristine was about 0.011 microM. The effect of SB203580 on L1210/VCR cells was associated with significantly increased intracellular accumulation of [3H]-vincristine in the concentration dependent manner. Prolonged exposure of resistant cells to 30 microM SB203580 did neither significantly influence the gene expression of P-gp, nor change the protein levels of p38-MAPK. Western blot analysis revealed that the MDR phenotype in L1210/VCR cells was associated with increased level and activity of cytosolic p38-MAPK. In resistant cells, the enhanced phosphorylation of both, p38-MAPK and ATF-2 (endogenous substrate for p38-MAPK) was found as well. In conclusion we could remark that SB203580, an inhibitor of p38 kinase pathway, reversed the MDR resistance of L1210/VCR cells. MDR phenotype of these cells is connected with increased levels and activities of p38-MAPK. These findings point to the possible involvement of the p38-MAPK pathway in the modulation of P-gp mediated multidrug resistance in the L1210/VCR mouse leukemic cell line. However, the mechanisms of SB203580 action should be further investigated.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2001

Elevated AT1 receptor protein but lower angiotensin II-binding in adipose tissue of rats with monosodium glutamate-induced obesity.

Age-related hypertrophy of adipose tissue has been associated with a significant decrease in the number of angiotensin II receptors. The aim of this study was to investigate the characteristics of angiotensin II receptors in hypertrophic adipose tissue in animal obesity model using rats postnatally treated with monosodium glutamate. Angiotensin II is known to induce hypertrophy in several tissues of the cardiovascular system and might do the same in fat tissue. The expression and binding properties of angiotensin II AT(1) receptors in epididymal fat tissue of adult rats were studied using membrane-binding, RT-PCR, and immunoblotting. The amount of AT(1) receptor mRNA did not differ significantly between obese and control rats. Despite that glutamate-treated rats displayed approximately 4-times more AT(1) receptor immunoreactive protein content in fat tissue cell membranes than the controls did. In contrast, binding experiments showed a significant (40.3 +/- 6.2 %) decrease of (125)I-Sar(1)-Ile(8)-angiotensin II-binding to fat tissue cell membranes in obese rats compared to controls. In conclusion, the present study provides evidence for the low binding properties associated with an accumulation of AT(1) receptor protein in cell membranes of the fat tissue of rats with glutamate-induced obesity. Discrepancies among angiotensin II-binding, AT(1) receptor protein, and AT(1) receptor mRNA levels indicate a possible defect in the receptor protein, which remains to be identified. The results obtained support a role of angiotensin II and AT(1) receptors in the pathogenesis of obesity.

1-Sarcosine-8-Isoleucine Angiotensin II↗

PubMed2001

Existence of cardiac PNMT mRNA in adult rats: elevation by stress in a glucocorticoid-dependent manner.

Phenylethanolamine N-methyltransferase (PNMT) is the enzyme that synthesizes epinephrine from norepinephrine. The aim of this study was to determine potential PNMT gene expression in the cardiac atria and ventricles of adult rats and to examine whether the gene expression of this enzyme is affected by immobilization stress. PNMT mRNA levels were detected in all four parts of the heart, with the highest level in the left atrium. Both Southern blot and sequencing verified the specificity of PNMT detected by RT-PCR. Single immobilization for 2 h increased gene expression of PNMT in both atria and ventricles. In atria, this effect was clearly modulated by glucocorticoids, because either adrenalectomy or hypophysectomy prevented the increase in PNMT mRNA levels in response to immobilization stimulus. This study establishes, for the first time, that PNMT gene expression occurs in cardiac atria and also, to a small extent, in ventricles of adult rats. Immobilization stress increases gene expression in atria and ventricles. This increase requires an intact hypothalamus-pituitary-adrenocortical axis, indicating the involvement of glucocorticoids.

Adrenalectomy↗

PubMed2001

Different expression of renin-angiotensin system components in hearts of normotensive and hypertensive rats.

Tissue renin-angiotensin systems are known to behave differently from the circulating renin-angiotensin system (RAS). It has already been proposed that not only the circulating RAS, but also RAS localized in the cardiac tissue plays an important role in the heart failure. The objective of this study was to compare the gene expression of individual components of the renin-angiotensin system in hearts of normotensive and hypertensive rats. Two genetically hypertensive rat strains--spontaneously hypertensive rats (SHR) and hereditary hypertriglyceridemic rats (HTG)--were compared with Wistar-Kyoto (WKY) and Lewis (LEW) normotensive controls. In addition, developmental changes in gene expression of individual components of cardiac RAS were studied in 20-day-old fetuses, 2-day-old newborns and 3-month-old HTG and LEW rats. In our study, the angiotensinogen gene expression did not differ either among adult normotensive and hypertensive strains, or during development. In contrast, the renin gene expression was significantly increased in hearts of hypertensive compared to normotensive rats. Moreover, a 5-fold increase of renin mRNA was observed in hearts of HTG rats between day 2 and the third month of age. There was also an age-dependent increase of ACE gene expression in both HTG and LEW rats which was substantially delayed in HTG hearts. In conclusion, the results of our study suggest that overexpression of the cardiac renin gene in hypertensive strains could participate in the structural and functional changes of the heart during the development of hypertension.

Angiotensinogen↗

PubMed2001

Nitric oxide synthase mRNA levels correlate with gene expression of angiotensin II type-1 but not type-2 receptors, renin or angiotensin converting enzyme in selected brain areas.

Recent data suggest that there is interaction between peripheral angiotensin II and nitric oxide. However, sparse information is available on the mutual interaction of these two compounds in the brain. The potential intercourse of nitric oxide with brain neuropeptides needs to be substantiated by assessing its local production and gene expression of the synthesizing enzymes involved. The aim of the present study was to evaluate whether the gene expression of brain nitric oxide synthase (bNOS) is related to the sites of gene expression of different components of the rat brain renin angiotensin system (renin, angiotensin converting enzyme (ACE) or angiotensin receptors of AT1 and AT2 subtypes). The levels of corresponding mRNAs were measured and correlated in nine structures of adult rat brain (hippocampus, amygdala, septum, thalamus, hypothalamus, cortex, pons, medulla and cerebellum). As was expected, positive correlation was observed between renin and angiotensin-converting enzyme mRNAs. Moreover, a significant correlation was found between brain NO synthase and AT1 receptor mRNAs, but not with mRNA of the AT2 receptor, ACE and renin. Parallel distribution of mRNAs coding for bNOS and AT1 receptors in several rat brain structures suggests a possible interaction between brain angiotensin 11 and nitric oxide, which remains to be definitely demonstrated by other approaches.

Amygdala↗

PubMed2000

Identification of type 1 IP(3) receptors in the rat kidney and their modulation by immobilization stress.

Inositol 1,4,5-trisphosphate receptor (IP(3)-receptor) is a calcium channel, transporting calcium from intracellular stores to the cytoplasm. In kidney, IP(3)-receptors are involved in the signal transduction of various hormones. In our work we studied the effect of immobilization stress on the IP(3)-receptor's protein content in renal cortex and the medulla of normotensive and hypertensive rats. We detected both mRNA and type 1 IP(3)-receptor protein in medulla, but not in renal cortex. We found that this receptor was approximately twice as abundant in normotensive as in genetically hypertensive rat kidney. Immobilization stress decreased the amount of type 1 IP(3)-receptor in the renal medulla of normotensive rats approximately five times, while no effect due to single and/or repeated stress was observed in the renal medulla of spontaneously hypertensive rats. The results indicate that expression of type 1 IP(3)-receptor in renal medulla is modulated by hypertension and immobilization stress.

Alternative Splicing↗

PubMed1999

[Structure and function of selected Ca(2+) transport systems in cardiac cells].

Transport systems, which transfer calcium across the plasma membrane or from the intracellular stores belong to important modulators of the intracellular calcium concentration. It is well known that the maintenance of the calcium homeostasis becomes the basis of the proper function of the heart muscle and its impairment leads to the development of the pathophysiological changes which may end in the cell death. Diversity of the calcium transport systems is given not only by their function (transfer of calcium across the plasma membrane in both direction) but also by their location (in the plasma membrane or in membranes of the intracellular stores). This review summarizes the current knowledge about the structure and function of selected calcium systems in the cardiac cells. We focused mainly on the L-type calcium channel, which is involved in the process of excitation and contraction coupling, and on the Na/Ca exchanger, which is considered to be an important system for the calcium extrusion from the heart cells.

Animals↗

PubMed1998

Correlation of M235T DNA polymorphism with cardiovascular and endocrine responses during physical exercise in healthy subjects.

In our experiments, we evaluated the possible effect of M235T molecular variant of the angiotensinogen gene on the response to a physical workload. A group of volunteers was composed of healthy male subjects, approximately of the same weight and height, same age and not actively trained. None of these subjects was under any medication. Blood sampling was carried out via an indwelling catheter. Besides blood pressure and heart rate, angiotensin I, angiotensin II, epinephrine and norepinephrine concentrations were measured in the blood. Our results suggest that only the response of diastolic blood pressure during submaximal exercise corresponded to the presence of M235T molecular variant. In all other parameters we found no significant correlation of the response with the M235T molecular variant.

Adult↗

PubMed1998

[Structure of the renin-angiotensin system and its significance in the body].

Renin-angiotensin system (RAS) is a methabolic pathway producing octapeptid angiotensin II (AII) with vasoconstrictive effects, which is also involved in the regulation of water homeostasis and electrolyte balance in the organism. Genes encoding individual components of the RAS can be considered as "candidate genes" for some cardiovascular diseases e.g. hypertension or myocardial infarction. Besides the circulating RAS, also local tissue systems exist. Local RASs are involved in various physiological functions e.g. regulation of growth and proliferation, apoptosis or signal transmission where AII serves as the neurotransmitter.

Angiotensins↗

PubMed1997

Nitric oxide and its effects on the calcium transport systems in the myocardium.

Nitric oxide (NO) is an important modulator of many physiological processes, including myocardial contractile function. The understanding of how the production of NO in the myocardium is regulated in response to physiological stimuli and pathological processes is evolving rapidly. The main goal of this minireview is to summarize the current knowledge (i) about the enzymes that produce NO in the heart muscle, (ii) about the targets of myocardial NO that modulate calcium transport systems of the heart muscle cells, and (iii) about the role that NO-induced changes of calcium homeostasis play in the modulation of myocardial contractility.

Animals↗