Lipopolysaccharide-induced redistribution of myocardial connexin43 is associated with increased macrophage infiltration in both normotensive and spontaneously hypertensive rats.

We investigated whether changes in gap junction alpha-1 protein (Cx43) expression may be associated with macrophage-induced inflammation in the heart of spontaneously hypertensive rats (SHR). To examine mutual interactions of macrophage infiltration with Cx43 expression and redistribution, we applied a bolus of bacterial lipopolysaccharide (LPS) to SHR and age-matched normotensive Wistar rats. The results demonstrated association of Cx43 downregulation with increased infiltration of cardiac CD-68 macrophages and upregulation of nuclear factor-κB (NFκB) and tumor necrosis factor-α (TNF-α) expression in the heart of SHR. LPS application to SHR caused further degradation and redistribution of Cx43 accompanied with extensively increased macrophage infiltration and NFκB and TNF-α expression. LPS administration to Wistar rats resulted in elevation of cardiac CD-68 macrophages but it did not significantly affect total Cx43 expression. Our results are suggestive of regulation of Cx43 expression with macrophages-related inflammation in the heart of SHR. The data also indicate that SHR can be more sensitive to LPS than are normotensive rats.

The vascular patterns of the posterior part of the circulus arteriosus cerebri (Willisi).

BACKGROUND: Various authors defined three patterns of the posterior part of the circulus arteriosus cerebri Willisi (CW) according to the diameter of the posterior communicating artery (PCoA) and the precommunicating segment of the posterior cerebral artery (P1). In the adult pattern, the P1 has a diameter larger than the non-hypoplastic PCoA. In the transitional pattern, the diameter of the PCoA is equal to that of the P1. In the fetal pattern, the diameter of the P1 is smaller than the diameter of the PCoA. The study was aimed to evaluate the configurations and calibers of the posterior part of the CW. METHODS: The work was conducted on 185 adult post-mortem brains. The CW and its branches were photographed by a digital camera. We used the software Image J to evaluate and process the gained images. RESULTS: The fetal pattern was found unilaterally in 8.37 %, and bilaterally in 4.86 %. The transitional pattern was observed unilaterally in 6.47 %, and bilaterally in 1 %. The prevalence of the unilateral and bilateral adult patterns was equal (21.62 % for each configuration). The hypoplastic PCoA was found unilaterally in 17.57 %, and bilaterally in 16.76 %. CONCLUSION: Various factors including genetic and environmental may affect the development of the cerebral vessels and their dimensions. The distinguishing of the vascular dimensions in vivo can help in the expectation and may be the avoidance of possible cerebrovascular disturbances in the future. Correlation and interdisciplinary cooperation of the studies dealing with morphology, radiology, and hemodynamics of the cerebral vessels are becoming an urgent need. The assumed results of this cooperation can be used in tabulating the calibers of the cerebral vessels and determining the threshold dimensions under which failure of hemodynamics and collateral function may appear (Tab. 2, Fig. 5, Ref. 28).

Use of graph algorithms in the processing and analysis of images with focus on the biomedical data.

INTRODUCTION: Image segmentation is a known problem in the field of image processing. A great number of methods based on different approaches to this issue was created. One of these approaches utilizes the findings of the graph theory. METHODS: Our work focuses on segmentation using shortest paths in a graph. Specifically, we deal with methods of "Intelligent Scissors," which use Dijkstra's algorithm to find the shortest paths. RESULTS: We created a new software in Microsoft Visual Studio 2013 integrated development environment Visual C++ in the language C++/CLI. We created a format application with a graphical users development environment for system Windows, with using the platform .Net (version 4.5). The program was used for handling and processing the original medical data. CONCLUSION: The major disadvantage of the method of "Intelligent Scissors" is the computational time length of Dijkstra's algorithm. However, after the implementation of a more efficient priority queue, this problem could be alleviated. The main advantage of this method we see in training that enables to adapt to a particular kind of edge, which we need to segment. The user involvement has a significant influence on the process of segmentation, which enormously aids to achieve high-quality results (Fig. 7, Ref. 13).

Omega-3 fatty acids and atorvastatin suppress ventricular fibrillation inducibility in hypertriglyceridemic rat hearts: implication of intracellular coupling protein, connexin-43.

Omega-3 fatty acids (omega-3 FA) and statins exhibit besides lipid-lowering effects the antiarrhythmic ability in clinic, while definite mechanisms are not yet elucidated. Our goal was to examine whether these compounds can modulate inducibility of hypertriglyceridemic (HTG) rat heart to ventricular fibrillation (VF) and myocardial cell-to-cell coupling protein connexin-43 (Cx43). HTG and healthy Wistar rats were orally treated with omega-3 FA(30 mg/100 g/day/2 mth) and atorvastatin (Ato, 0.5 mg/100 g/day/2 mth) and compared to untreated rats. Susceptibility of the heart to electrically-inducible VF and functional parameters were monitored using Langendorff-perfused isolated heart. Ventricular tissues from treated and untreated HTG and Wistar rat hearts were processed for ultrastructure examination as well as for analysis of myocardial Cx43 distribution and expression using antiCx43 MAB, immunofluorescence and immunoblotting. Both, omega-3 FA and atorvastatin reduced elevated blood pressure, triglycerides and heart rate in HTG rats. Compared to Wistar the threshold to induce VF was lower in HTG rat hearts, which exhibited abnormal Cx43 distribution, decreased immunostaining and elevated phosphorylated form of Cx43. In contrast, an enhancement of immunostaining of Cx43, suppression of hyperphosphorylation of Cx43 and improvement of cardiomyocyte and intercellular junction integrity by omega-3 FA and atorvastatin was associated with a significant increase of threshold for VF. Moreover, treatment resulted in up-regulation of myocardial Cx43 and increase of VF threshold in healthy rats that was associated with up-regulation of Cx43. Results indicate that antiarrhythmic effects of omega-3 FA and atorvastatin are linked with modulation of expression and/or phosphorylation of Cx43 and protection of cardiomyocyte and cell-to-cell junction integrity. As both compounds are ligands for PPAR, a possible regulation of Cx43 gene expression and pathways involved in Cx43 phosphorylation should be investigated.

Modulation of connexin-43 by omega-3 fatty acids in the aorta of old spontaneously hypertensive rats.

Hypertension alters expression of connexin-43 (Cx43) in cardiovascular system. The aim of the study was to investigate the effect of omega-3 polyunsaturated fatty acids (30 mg/day for 2 months) on expression of Cx43 in the aorta of 1-year-old male spontaneously hypertensive rats (SHR). Spatial distribution and expression of Cx43 in aortic wall of SHR and age-matched Lewis rats were determined by immunofluorescent method and Western blot. NO synthase (NOS) activity and endothelium-dependent relaxation of the aorta were measured as well. Immunofluorescent pattern of Cx43 was identified in endothelial and smooth muscle cells of the aorta of all experimental groups studied. However, local decrease in the number and intensity of fluorescent spots and reduced phosphorylation of Cx43 were observed in SHR in contrast to normotensive LEW. Omega-3 fatty acid diet increased Cx43 immunolabeling in endothelium and media of SHR comparing to untreated ones. Parallel, 3-fatty acids significantly elevated phosphorylation of Cx43 in the aorta of SHR (p<0.001). Despite the omega-3 fatty acids reduced blood pressure and stimulated aortic NOS activity in SHR, endothelium-dependent relaxation of the aorta did not significantly change. Results indicate that the aorta of old SHR might partially benefit from 3-PUFA supplementation due to increased Cx43 phosphorylation, NOS activity and decreased blood pressure.

The detection of circulating tumor cells expressing E6/E7 HR-HPV oncogenes in peripheral blood in cervical cancer patients after radical hysterectomy.

The aim of this study was to establish the sensitive, specific and clinically acceptable method for detection of tumor cells (TCs) circulating in peripheral blood (PB) of cervical cancer patients without the clinically detectable risk of disease progression. The 7.5 ml of PB of healthy donor was spiked with 5 to 100 cells from SiHa or HeLa cell lines. The spiked tumor cells were collected without gradient centrifugation, by standard gradient centrifugation or by modified gradient centrifugation combined with immunomagnetic separation using EpCAM antibody with affinity for epithelial cell adhesion molecule. The number of collected TCs was determined by EpCAM-FITC-staining and their viability was detected by nested RT-PCR amplifying E6/E7 HR-HPV 16 or HR-HPV 18 oncogenes. For the technical validation of this approach the TCs separation and RT-PCRs were repeated several times. The recovery of viable TCs was reproducibly higher using modified gradient centrifugation combined with immunomagnetic separation in comparison with standard approach. The recovery of TCs in low number of spiked TCs (range from 5 - 20 TCs in 7.5 ml of PB) using modified gradient centrifugation was not reproducible. The recovery of TCs in higher number of spiked TCs (25 TCs and more in 7.5 ml of PB) was reproducible with average recovery about 50 %. The sensitivity of nested RT-PCR amplifying E6/E7 oncogenes was decisively influenced by the number of recovered TCs and the amount of cDNA introduced to RT-PCR, as well. Using this approach we were allowed to detect circulating TCs (CTCs) in cervical cancer patients without metastases, thus this procedure might become a tool to early estimation of disease progression. According to our knowledge, this is the first report describing the use of EpCAM antibody for CTCs detection in cervical cancer patients.

Thyroid hormones suppress epsilon-PKC signalling, down-regulate connexin-43 and increase lethal arrhythmia susceptibility in non-diabetic and diabetic rat hearts.

We examined whether thyroid hormones affect myocardial epsilon-PKC signalling, downstream target substrate, connexin-43 (Cx43) and arrhythmogenesis in non-diabetic and diabetic rats. Diabetes was induced by a single streptozotocin injection (50mg/kg, i.v.). Triiodothyronine (T(3)) was applied by gavage (1microg/kg of body weight for 10 days) to 4 weeks and 9 weeks diabetic and age-matched non-diabetic rats. Western blot analysis of Cx43 and epsilon-PKC, immunofluorescence of Cx43, ultrastructure of cardiomyocytes and myocardial conduction velocity were performed. Isolated perfused heart preparation was used to test ventricular fibrillation susceptibility. T(3) significantly decreased epsilon-PKC expression in non-diabetic and suppressed in diabetic rat heart ventricles. Decline of epsilon-PKC signalling was associated with decrease of Cx43 phosphorylation in diabetic and to a greater extent in non-diabetic rat hearts. However, conduction velocity was significantly decreased in diabetic while enhanced due to T(3) and increased in non-diabetic T(3)-treated rat heart ventricles compared to non-treated. T(3)-induced down-regulation of Cx43 was associated with increased cardiac propensity to ventricular fibrillation. Findings indicate that activation of epsilon-PKC signalling linked with phosphorylation of Cx43 is one of the mechanisms involved in the adaptation of the heart to hyperglycemia. Suppression of epsilon-PKC and Cx43 phosphorylation by T(3) abolish benefit of adaptation rendering the heart prone to lethal arrhythmias.

Aged male and female spontaneously hypertensive rats benefit from n-3 polyunsaturated fatty acids supplementation.

Hypertension-induced myocardial metabolic, structural and electrophysiological remodeling deteriorates with aging and contributes to both heart failure and occurrence of malignant arrhythmias. It has been shown in clinical trials that n-3 polyunsaturated fatty acids (n-3 PUFA) reduce the incidence of cardiovascular diseases and sudden cardiac death. We investigated the cardioprotective effects of n-3 PUFA in aged spontaneously hypertensive rats (SHR) and possible cellular mechanisms involved. Male and female 14-moth-old SHR were fed with n-3 PUFA (Vesteralens, Norway, 20 mg/day for two months) and compared with untreated SHR. Results showed that n-3 PUFA supplementation led to 1) significant decline of blood pressure; 2) suppression of inducible ventricular fibrillation (VF) by 57 % (male) and 67 % (female), although the arrhythmogenic substrates, like fibrosis, hypertrophy and abnormal gap junctions distribution were not eliminated; 3) preservation of the cardiomyocytes and the integrity of their junctions; 4) enhancement of energetic metabolism enzyme activity; 5) augmentation of capillary density associated with increased alkaline phosphatase and decreased dipeptidyl peptidase-4 (DPP4) activity and 6/ increase in gap junction channel connexin-43 expression. Thus, aged male as well as female SHR benefit from n-3 PUFA supplementation that results in decrease in VF susceptibility, partly due to an improvement of myocardial metabolic state, cardiomyocyte and cell-to-cell junctions integrity and Cx43 up-regulation.

Reduced connexin-43 expression in the aorta of prehypertensive rats.

Genetic component represents an important factor in the development of hypertension, which is known to be associated with changes in expression of vascular gap junction protein connexin 43 (Cx43). The aim of the study was to examine the distribution and expression of Cx43 in the aortic endothelium of adult normotensive Wistar rats (W), borderline hypertensive rats (BHR) and spontaneously hypertensive rats (SHR). Rings of the thoracic aorta were processed for immunofluorescence and Western blot analysis of endothelial Cx43 and for electron microscopy. Both, BHR and SHR exhibited significantly increased blood pressure vs. W (132+/-2 mm Hg and 185+/-3 mm Hg vs. 110+/-2 mm Hg). Reduced Cx43 immunofluorescence was observed in the endothelium of BHR and these alterations were more pronounced in SHR. Western blot analysis showed significant suppression of Cx43 expression in the aorta of both BHR (p<0.05) and SHR (p<0.001) vs. W. Electron microscopy revealed local subcellular alterations of interendothelial connections in BHR including extended tight junctions. These alterations were more frequent and marked in SHR. The results indicate that connexin 43 expression is reduced in the aortic endothelium already in prehypertensive period, which may affect cell-to-cell communication and thus participate in acceleration of hypertensive disease.

The spectrum and incidence of BRCA1 pathogenic mutations in Slovak breast/ovarian cancer families.

Pathogenic germline mutations in BRCA1 and BRCA2 account for the majority of hereditary breast/ovarian cancer cases. The analysis of BRCA1 gene was carried out in 156 breast/ovarian cancer families: 82 families with strong family history and 59 families with medium family history. Generally, 31 families and 71 cases with BRCA1 pathologic mutations (14 different types) were identified in this study by combination of SSCP and direct sequencing techniques. Using approved systematic nomenclature numbering, c.5266dupC (8 families, 21 cases), c.181T>G (5 families, 11 cases), c.68_69delAG (3 families, 5 samples) and c.843_846del4 (3 families, 4 samples) were the most frequently found mutations in BRCA1 gene. Altogether these 4 mutations accounted for 61.3% of all detected pathogenic mutations in BRCA1. One novel mutation c.1166delG was detected in one family (4 cases). Frame-shift mutations were found in 21 families (46 cases), nonsense mutations in 4 families (8 cases) and missense mutations in 6 families (17 cases). Even though the 4 most frequent mutations account for 61.3% of all detected pathogenic mutations, screening of the whole BRCA1 coding region is necessary, due to the large scale of low frequency disease causing mutations in breast/ovarian cancer families in Slovakia.

Factors involved in the susceptibility of spontaneously hypertensive rats to low K+-induced arrhythmias.

Disorders of intracellular Ca2+ homeostasis and intercellular coupling are thought to be crucial in the initiation and maintenance of malignant arrhythmias. The aim of this study was to investigate possible arrhythmogenic factors in spontaneously hypertensive rats (SHR) as well as their susceptibility to low K+-related arrhythmias. The experiments were performed on isolated hearts of 13 weeks-old SHR and age-matched Wistar Kyoto rats (WKY). Equilibration of the heart by Langendorff perfusion with oxygenated, 37 degrees C warm, standard Krebs solution at a constant pressure was followed by perfusion with low K+ solution for 60 min, unless sustained ventricular fibrillation occurred earlier. Electrocardiogram and epicardial monophasic action potentials (MAPs) were continuously monitored for incidence of arrhythmias and action potential changes. Myocardial tissue was taken for ultrastructural analysis and immunodetection of the main gap junction protein, connexin-43. The results showed that hypertrophic hearts of SHR exhibited prolongation of MAPs and a decrease in phosphorylation of connexin-43. Moreover, they were more prone to low K+-induced early after-depolarisations and ventricular premature beats as well as to connexin-43 and ultrastructural alterations than WKY rats. Consequently, the incidence of ventricular tachycardia (70% vs. 50%) and both transient (50% vs. 25%) and sustained (60% vs. 25%) ventricular fibrillation was higher in SHR than WKY rats. The results suggest that both prolongation of MAP and connexin-43 alterations are important arrhythmogenic factors facilitating arrhythmias in the setting of Ca2+ disorders due to hypokalaemia.

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.

L-arginine reduces structural remodeling in the diabetic rat myocardium.

Metabolism, monitored via in situ catalytic enzyme histochemistry and fine structure, was studied in the myocardium of chronic diabetic male Wistar rats administered L-arginine (12.8 mg/100 g/day) for 24 weeks. Diabetes was induced with a single i.v. injection of 55 mg/kg streptozotocin. After 6 months, the tissue of the left ventricle was processed for electron microscope examination and transmural tissue blocks were frozen for enzyme histochemistry. In diabetic myocardium, heterogeneous ischemia-like subcellular alterations of cardiomyocytes and capillaries were observed, together with interstitial fibrosis. This structural remodeling was accompanied by significantly decreased activity of endothelial nitric oxide synthase (NOS) and heterogeneously decreased activities of glycogen phosphorylase (GlPh), hydroxybutyrate dehydrogenase (HBDH) and adenosine triphophatases (ATPases) throughout the myocardium. In arginine-treated diabetic rats, there was evidence of protected structural integrity of endothelial cells and attenuated structural disturbances of cardiomyocytes. This was associated with the markedly preserved histochemical activities of all detected enzymes in comparison with nontreated diabetic rats (NOS 98.7 +/- 10.5% vs. 35.4 +/- 4.1%; ATPases 82.7 +/- 9.1% vs. 69.3 +/- 5.2%; GlPh 65.2 +/- 8.3% vs. 45.5 +/- 3.8%; HBDH 68.9 +/- 8.5% vs. 44.1 +/- 6.7% of control values). The results indicate that long-term supplementation of L-arginine may account for the reduction of diabetes-induced myocardial structural remodeling.

Hypertension-related intermyocyte junction remodelling is associated with a higher incidence of low-K(+)-induced lethal arrhythmias in isolated rat heart.

The aim of this study was to characterise the arrhythmogenic mechanisms involved in hypokalaemia-induced sustained ventricular fibrillation (SVF), in hypertensive rats. The hearts from rats with hypertension induced by the nitric oxide synthase inhibitor L-NAME, and age-matched normotensive controls, were perfused in Langendorff mode with oxygenated Krebs-Henseleit solution followed by a K(+)-deficient solution. In additional experiments, free intracellular Ca(2+) concentration ([Ca(2+)](i)) was measured using fura-2 in conjunction with an epicardial optical probe. The epicardial electrocardiogram was continuously monitored during all experiments. The gap junction protein connexin-43 and the ultrastructure of the cardiomyocytes were examined, and selected enzyme activities were measured in situ. There was a higher incidence of low-K(+)-induced SVF in the hearts of hypertensive compared to normotensive rats (83 % vs. 33 %, P < 0.05). Perfusion with a low-K(+)-containing solution lead to elevation of diastolic [Ca(2+)](i) that was accompanied by premature beats, bigeminy, ventricular tachycardia and transient ventricular fibrillation. These events occurred earlier with increased incidence and duration in the hearts of hypertensive rats (arrhythmia scores: hypertensive, 4.9 +/- 0.7; normotensive, 3.1 +/- 0.1; P < 0.05), which exhibited apparent remodelling accompanied by a significant decrease in the density of connexin-43-positive gap junctions. Moreover, low-K(+)-related myocardial changes, including local impairment of intermyocyte junctions, ultrastructural alterations due to Ca(2+) overload and intercellular uncoupling, and decreased enzyme activities were more pronounced and more dispersed in hypertensive than normotensive rats. In conclusion, nitric oxide-deficient hypertension is associated with decreased myocardial coupling at gap junctions. The further localised deterioration of junctional coupling, due to low-K(+)-induced Ca(2+) disturbances, as well as spatial heterogeneity of myocardial alterations including interstitial fibrosis, probably provide the mechanisms for re-entry and sustaining ventricular fibrillation.

The pyridoindole antioxidant stobadine attenuates albuminuria, enzymuria, kidney lipid peroxidation and matrix collagen cross-linking in streptozotocin-induced diabetic rats.

The aim of the present study was to investigate the effect of dietary supplementation with the pyridoindole antioxidant stobadine on kidney status and function in streptozotocin-induced diabetic rats. Diabetic male Wistar rats were fed a standard diet for 32 weeks or a diet supplemented with stobadine (0.05% w/w). The diabetic state was characterized by significantly elevated plasma levels of glucose, HbA1c and urea, severe reduction of total body weight and relatively enlarged kidneys. Elevated levels of conjugated dienes were recorded in the diabetic kidney confirming the presence of oxidative stress in diabetic animals. All diabetic rats showed marked proteinuria and albuminuria along with elevated excretion of the enzyme N-acetyl-beta-D-glucosaminidase. Long-term treatment of diabetic animals with stobadine significantly reduced total proteinuria, albuminuria and enzymuria, yet left the overall physical and glycemic status unaffected. It reduced oxidative damage of kidney tissue as shown by decreased conjugated diene level, and decreased matrix collagen cross-linking, as indicated by decreased breaking time values of rat tail tendons. These beneficial effects of stobadine, supported also by histological findings, may be brought about by virtue of the combination of its antioxidant potential with other effects, e.g., the postulated cholesterol-lowering ability or its ability to alter vascular reactivity and reduce the vascular tone.

The determination of the collagen and elastin amount in the human varicose vein by the computer morphometric method.

The results of the works dealing with alterations of the connective tissue in varicose vein wall are not ambiguous, so the exact cause of the vein dilatation has still not been established. We were determining the collagen and elastin amounts in human varicose vein wall in comparison with non-dilated long saphenous vein by the light microscopy and computer morphometric method. We have found the lesser amount of collagen in varicose veins than in non-dilated veins, the amounts of the elastin in both the varicose and non-varicose veins were without the statistical significance.

Both iso- and hyperosmotic ethanol stimulate release of hypothalamic thyrotropin-releasing hormone despite opposite effect on neuron volume.

Previous studies have indicated that isosmolar, but not hyperosmolar, ethanol induces in vitro gonadotropin-releasing hormone secretion from the basal hypothalamus, presumably by causing cell swelling. Moreover, ethanol reduces secretion of another hypothalamic neuropeptide vasopressin. We have studied the acute effect of ethanol on specific hypophysiotropic basal and K+-stimulated thyrotropin-releasing hormone secretion in vitro especially in relation to cell swelling. Isosmotic 40-160 mM ethanol increased thyrotropin-releasing hormone release from the hypothalamic paraventricular nucleus and median eminence in a dose-dependent manner. Both a 30% decrease of osmolarity and isosmotic 80 mM ethanol induced 12% swelling of hypothalamic neurons. Hyperosmotic 80 mM or 160 mM ethanol induced release of thyrotropin-releasing hormone from both hypothalamic structures but did not cause cell swelling (80 mM) or even induced cell shrinkage (160 mM). Depletion of medium Ca2+ did not affect thyrotropin-releasing hormone secretion caused by either isosmotic or hyperosmotic ethanol. Our data indicate that both iso- and hyperosmotic ethanol stimulated release of hypophysiotropic thyrotropin-releasing hormone despite opposite effects on neuron volume. The mechanism of ethanol action appears complex and variable depending on the type of cell and neuropeptide affected.

[Morphometric analysis of the spleen]. / Skúsenosti s morfometrickou analýzou sleziny.

Present possibilities of morphometric analysis of the spleen have been studied. We have compared possibilities provided by stereological calculation and by computer image analysators a) Telemet II (Tesla, Piestany) and b) CUE-2 GALAI (Israel). In both latter cases equidensitometric evaluation and image processing methods were used. Stereological calculations are not technically demanding but time consuming. Computer image processing on the base of equidensitometric measurements is more effective that stereological calculations. The difference between used equipments is based on access to appropriate microscopic and computer technique and software equipment.

Change in phenotype of tick-borne encephalitis virus following passage in Ixodes ricinus ticks and associated amino acid substitution in the envelope protein.

Serial passage of an uncloned tick-borne encephalitis virus (strain 4387 isolated from the liver and lungs of a bank vole) in Ixodes ricinus ticks, was accompanied by gradual reduction in virulence of the virus, as indicated by transmission of virus by infected ticks feeding on laboratory mice. After the 7th serial passage in ticks (strain 4387/7), 95% of mice survived the bite of infected ticks. The surviving infected mice showed either no or only low viraemia although virus could be isolated from the brains of some mice 14 and 30 days after commencement of tick feeding, implying that the tick passaged virus might have established a persistent infection in the mice. Tests for haemagglutinating capacity were positive with TBE strain 4387 but strain 4387/7 exhibited no haemagglutinating activity over a wide pH range, suggesting that phenotypic changes, resulting from selection, had affected the site on the viral envelope protein that binds red blood cell receptors. Sequencing of the envelope protein gene of the virulent TBE strain 4387 showed 3 amino acid codon differences from western European TBE virus strain Neudorfl, which is also virulent for mice. The attenuated virus 4387/7, had an amino acid substitution that was different from 4387 and Neudorfl TBE virus (amino acid 84, E to K) and a second substitution different from 4387 but identical to Neudorfl virus (amino acid 319, I to T). Thus, the phenotypic change from virulence to attenuation was associated with a single amino acid codon change in the viral envelope gene of TBE virus. It is recognised, however, that amino acid substitutions in other parts of the viral genome have not been ruled out.

Interference between the viruses of tick-borne encephalitis complex in the Ixodes ricinus ticks.

The interference of two closely related viruses of the tick-borne encephalitis complex (TBE) in Ixodes ricinus ticks has been observed. 42.9 to 65.0% of dually infested ticks developed virus neutralization antibodies in mice without signs of illness, which contrasts with the control ticks infected with 198 strain only. Other explanations of this interference could include alteration of viral receptors on host cells or induction of antiviral activity in the infected ticks and/or other vectors such as mosquitoes.