Biomedical subjects

Dusan Suput

Publications and source records attributed to Dusan Suput.

13 recordsLinked to original sources

PubMed2006

Increased cognitive load during simple and complex motor tasks in acute stage after stroke.

UNLABELLED: The aim of this study was to assess the activation of primary motor cortex, prefrontal cortex and parietal cortex during simple and complex motor tasks performed with the hemiparetic and non-hemiparetic hand. METHODS: Seven patients after stroke in the left brain hemisphere were included in the study. Functional magnetic resonance imaging (fMRI) was performed in the first and third week, and in three patients also three months after the stroke. RESULTS: Performance of both the simple and the complex tasks with the hemiparetic or non-hemiparetic hand resulted in activations of the motor cortex, prefrontal cortex and parietal cortex in majority of the consecutive fMRI sessions. Three months after the stroke fMRI data revealed reduced activation of primary motor cortex and parietal cortex in the contralesional hemisphere during the performance of the simple task by the hemiparetic hand. During the complex task, the reduction of activation was less prominent. CONCLUSIONS: Results of the present study suggest that in mildly impaired stroke patients a bilateral activation of prefrontal and parietal cortex may participate in the recovery process from stroke. The potential for measurement of cortical rehabilitation is discussed.

Aged↗

PubMed2006

Immediate oxygen therapy prevents brain cell injury in carbon monoxide poisoned rats without loss of consciousness.

In CO-poisoned patients without loss of consciousness no significant long-term functional differences in outcome have been shown in any hyperbaric versus normobaric oxygen studies. Since brain histology changes cannot be studied in CO-poisoned patients we evaluated the efficacy of normobaric and hyperbaric oxygen therapy in preventing brain cell injury in CO-poisoned animals without loss of consciousness. Wistar rats without loss of consciousness after exposure to 3000ppm of CO for 60min were exposed to ambient air (group 1), 100% oxygen at a pressure of 1bar (group 2) and 100% oxygen at a pressure of 3bar (group 3). The rats were sacrificed after two weeks, brain samples were stained with hematoxylin-eosin and a percentage of pyknotic cells in hippocampus was reported. Analyses of differences in percentage of pyknotic cells between different kinds of therapy showed that the percentage of pyknotic cells of the second group (2.3+/-1.2%) treated with normobaric oxygen and the third group (4.5+/-4.0%) treated with hyperbaric oxygen were similar, and both of them were significantly different, with a much lower percentage of pyknotic cells, from the first group left on ambient air (47.7+/-10.0%). In conclusion, immediate normobaric and hyperbaric oxygen therapy equally prevents hippocampal cell injury in CO-poisoned rats without loss of consciousness.

Animals↗

PubMed2006

S100B protein in conscious carbon monoxide-poisoned rats treated with normobaric or hyperbaric oxygen.

OBJECTIVE: To evaluate S100B, an astroglial structural protein, during normobaric and hyperbaric oxygen therapy of conscious carbon monoxide (CO)-poisoned rats. So far, the usefulness of hyperbaric oxygen therapy in conscious CO-poisoned patients has been shown with neuropsychological testing. The S100B protein has been demonstrated as a possible biochemical marker and prognostic parameter in CO-poisoned rats. DESIGN: Randomized, controlled interventional trial. SETTING: University laboratory. SUBJECTS: : Male Wistar rats weighing 254 +/- 14 g. INTERVENTIONS: The rats were exposed to a mixture of 3,000 ppm CO in air for 60 mins. After CO exposure, the first group of eight conscious rats was exposed to ambient air for 30 mins, the second group of six conscious rats was exposed to 100% normobaric oxygen for 30 mins, and the third group of six conscious rats was exposed to 100% hyperbaric oxygen at 3 bars for 30 mins. Blood samples were taken from the jugular vein just before CO exposure and immediately after oxygen therapy. The level of consciousness was evaluated at the end of exposure, and the survival rate was monitored for 14 days. The S100B concentrations were measured with a commercial immunoluminometric assay. MEASUREMENTS AND MAIN RESULTS: Analyses of differences in S100B levels between different kinds of therapy before and after treatment showed a global significant difference (p = .002). The post hoc test results showed that S100B levels after therapy of the first group treated with ambient air (0.16 +/- 0.07 microg/L) and the second group treated with normobaric oxygen (0.19 +/- 0.05 microg/L) were similar (p = .741), and both of them were significantly different, with much higher values of S100B levels after therapy, from the third group treated with hyperbaric oxygen (0.06 +/- 0.03 microg/L; p = .018 and p = .002, respectively). All the rats survived. CONCLUSIONS: S100B is elevated in conscious CO-poisoned rats left on ambient air or treated with normobaric oxygen, but not in conscious CO-poisoned rats treated with hyperbaric oxygen.

Animals↗

PubMed2006

Overexpression of caspase-9 triggers its activation and apoptosis in vitro.

AIM: To investigate the consequences of increased expression of caspase-9: 1) whether the caspase-9 overexpression resulted in cell death through apoptosis, 2) whether apoptosis could be triggered in normal and tumor cells, and 3) what is the role of caspase-9 in the process. METHODS: The caspase-9 fused to green fluorescent protein was expressed in primary cultures of anterior pituitary cells and of HeLa tumor cells. The expressed caspase-9 and the number of apoptotic and necrotic cells were determined using fluorescence microscopy. RESULTS: Overexpression of caspase-9 resulted in cell death of primary pituitary cells and HeLa cells. More than 94% of the cells died of apoptosis, which was triggered by the activation of caspase-9, since the cell deaths were prevented in the presence of caspase-9 specific inhibitor. HeLa cells were about 50% more resistant to apoptosis than pituitary cells. CONCLUSIONS: Caspase-9 overexpression and its activation leads to apoptosis. It occurs both in normal and tumor cells. Since the majority of cancer therapy treatments initiate apoptosis through the caspase-9 activation, the modulation of caspase-9 expression may be exploited in designing new ways to control apoptosis in neurodegenerative or malignant diseases.

Animals↗

PubMed2004

Prognostic value of S100B protein in carbon monoxide-poisoned rats.

OBJECTIVE: To assess the possible role of S100B, a structural protein of astroglial cells, as a biochemical marker in acute carbon monoxide-poisoned rats and to compare its prognostic value with consciousness level, which is one of the major parameters for treatment decision in acute carbon monoxide poisoning. DESIGN: Nonrandomized, controlled interventional trial. SETTING: University laboratory. SUBJECTS: Male Wistar rats weighing 263 +/- 18 g. INTERVENTIONS: The rats were exposed to a mixture of 3000 ppm carbon monoxide in air for 60 mins (group 1) and a mixture of 5000 ppm carbon monoxide in air for 30 mins (group 2). Blood samples were taken from the jugular vein just before and immediately after the carbon monoxide poisoning. The level of consciousness was evaluated at the end of the exposure, and the survival rate was monitored for 7 days. The S100B concentrations were measured with a commercial immunoluminometric assay. MEASUREMENTS AND MAIN RESULTS: In the first group, the unconscious rats after carbon monoxide exposure had significantly higher S100B levels compared with the rats without loss of consciousness. In the second group, the unconscious rats that later died had significantly higher S100B levels compared with the unconscious rats that survived. The S100B levels of all conscious and unconscious surviving rats were not significantly different. The serum level of S100B below 0.44 microg/L predicted survival of carbon monoxide-poisoned rats, with a sensitivity of 100% and a specificity of 86%. CONCLUSIONS: Acute carbon monoxide poisoning is associated with elevated S100B levels. S100B is a better predictor of final outcome than the consciousness level, so it could be used as a prognostic parameter for acute carbon monoxide poisoning in rats.

Animals↗

PubMed2003

Microcystin-LR causes the collapse of actin filaments in primary human hepatocytes.

Microcystin-LR (MCLR) is a potent inhibitor of protein phosphatases 1 and 2A and causes alterations in cytoskeletal filaments and morphological changes that underlie apoptosis in rat hepatocytes. It has also been reported that it caused several cases of human deaths and illness. As no study on the effect of microcystins on human hepatocytes was done, yet, the aim of the study is to evaluate the toxicity of MCLR on primary human hepatocytes. The hepatocytes were incubated in 12.5-50 nM MCLR for 3, 6 and 9 h, fixed and stained with fluorescent probes for actin filaments and nuclei. Spectral laser-scanning confocal microscopy revealed that in the MCLR-treated primary human hepatocytes the actin mesh collapsed into the center of the cell, similarly as it has been described for rat hepatocytes. Cells were blebbing, fragmenting, and separated from each other. The nuclei in the affected cells condensed. In conclusion, this study confirms that MCLR is toxic to primary human hepatocytes, and it may be responsible for the liver failure cases observed after acute cyanobacterial poisoning.

Actin Cytoskeleton↗

PubMed2003

Nephrotoxic effects of chronic administration of microcystins -LR and -YR.

Acute intoxication with MC-LR induces cytoskeletal alterations, apoptosis and necrosis of hepatocytes resulting in intrahepatic hemorrhage. Preliminary results have shown that chronic treatment of rats with intraperitoneal injections of sublethal doses of microcystins MC-LR and MC-YR could induce not only liver, but also kidney injuries. We aimed to investigate whether the induction of the cytoskeletal changes, apoptosis and necrosis could be the mechanisms involved in the injury of kidney cells in the chronic model of microcystin intoxication. Experimental rats were receiving intraperitoneal injections of MC-LR (10 microg/kg) or MC-YR (10 microg/kg) every second day for 8 months, while control rats were receiving only the vehicle. The histopathological investigation revealed collapsed glomeruli with thickened basement membranes and dilated tubuli filled with eosinophilic casts. Rhodamine-phalloidin labeling showed cytoplasmic aggregation and accumulation of fibrilar actin filaments within the epithelial tubular cells. Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) showed increased number of TUNEL-positive cells in the kidney cortex and medulla. The pathological changes induced by MC-LR appeared more severe than those induced by MC-YR. The results support the view that at the cellular level, the mechanisms that underly the chronic nephrotoxicity are similar to the mechanisms of the acute hepatotoxicity of microcystins.

Analysis of Variance↗

PubMed2002

Toxic effects of head-to-tail 3-alkylpyridinium polymers isolated from the marine sponge Reniera sarai in rat.

Toxic water soluble polymeric 3-alkylpyridinium salts (poly APS; MW 18900 and 5520Da) were isolated from the marine sponge Raniera sarai. In vitro they strongly inhibited acetylcholinesterase. In order to evaluate the role of acetylcholinesterase inhibition in toxin lethality, and to assess other possible lethal effects, in vivo experiments were performed on male Wistar rats, and ECG, blood pressure and breathing pattern were monitored. The results showed that none of the animals died due to the acetylcholinesterase inhibitory action of poly-APS. Doses lower than 1mg/kg caused only transient bradycardia and transient prolongation of expirium. At doses above 2.7mg/kg of poly-APS all treated animals died, but signs were not typical of acetylcholinesterase inhibition. Arterial blood pressure fell to mid-circulatory pressure, and breathing stopped after a few breaths with an increase of the residual volume. Autopsy of the experimental animals that died due to the effects of the toxin revealed that mid-size and small sized blood vessels in the heart and lungs were filled with granular brownish material with inclusions of red blood cells and platelets. Data obtained on blood samples from animals treated with poly-APS also revealed numerous thrombocyte aggregates. In vitro poly-APS induced thrombocyte aggregation in a dose dependent manner. The acetylcholinesterase-inhibitory effects were most pronounced only at lower doses of poly-APS. With higher doses those effects were masked or covered by other, more pronounced and faster developing lethal effects of the toxin such as platelet aggregation. Therefore it is reasonable to assume that acetylcholinesterase inhibitory effects are not responsible for the lethal activity of the toxin.

Animals↗

PubMed2002

Renal injuries induced by chronic intoxication with microcystins.

The microcystins (MCs) LR and YR are hepatotoxins produced by some species of freshwater cyanobacteria. Only a few reports on the acute nephrotoxicity of MCs have been published to date. Here we investigate the effects on rat kidneys of chronic administration of relatively low doses of MC LR and MC YR. Male Wistar rats were injected every second day for 8 months with MC LR (10 microg/kg i.p., n=5) and MC YR (10 microg/kg i.p., n=5). The control group was treated with vehicle, a mixture containing 0.8 % ethanol and 0.2 % methanol in 0.9 % saline (3.7 ml/kg i.p., n=5). We found that MCs could induce damage to the kidney cortex and medulla. The lesions mainly consisted of damaged and dilated tubuli filled with homogenous eosinophil material. We conclude that long-term exposure to relatively low doses of MCs poses a considerable risk for kidney injury.

Animals↗

PubMed2002

Ionic mechanisms involved in the nodal swelling of myelinated axons caused by marine toxins.

This review describes the ionic mechanisms involved in the nodal swelling of frog myelinated axons caused by specific marine neurotoxins (ciguatoxins, brevetoxins, Conus consors toxin and equinatoxin-II), analysed using confocal laser scanning microscopy. We have focussed on toxins that either target neuronal voltage-dependent Na+ channels, or that form cation-selective pores and indirectly affect the functioning of the Na(+)-Ca(++)exchanger.

Animals↗

PubMed2002

Equinatoxin II-induced lysis Of the cultured endothelial cell line ECV-304.

Equinatoxin II (EqT II) is a pore-forming actinoporin. Its lethality in rat tissue is due to cardio-respiratory effects. The toxin contracts the vascular smooth muscle only in the presence of intact endothelium. In our study, its effects on the endothelial cell culture ECV-304 were tested. The EqT II effects were dose-dependent and were influenced by calcium ions and sucrose. The obtained results support the conclusion that calcium ions are the intracellular messengers of the EqT II effects on the isolated endothelial cells.

Cell Line↗

PubMed2002

Nicardipine diminished equinatoxin II-induced decrease of coronary flow in isolated rat and pig hearts.

Equinatoxin II (EqT II) is a basic, cardiotoxic polypeptide. The vasoconstrictory effect of the toxin on isolated porcine coronary arteries was diminished by nicardipine, an L-type calcium channel antagonist. A comparison was made of the effects of EqT II alone and EqT II in the presence of nicardipine on the coronary flow in porcine and rat hearts isolated according to Langendorff's method. In both models EqT II decreased coronary flow in a dose-dependent manner and there were no statistically significant differences between the two models (p>0.05). However, 1 M nicardipine diminished the effects of EqT II on coronary flow in isolated porcine hearts more than in isolated rat hearts (p<0.05). The results suggest that the activation of L-type calcium channels is one of the mechanisms involved in the lowering of coronary flow induced by EqT II.

Animals↗

PubMed2002

Tezosentan inhibits both equinatoxin II and endotelin-1 induced contractions of isolated porcine coronary artery in a similar way.

In the present study we examined the endothelium-dependent mechanism in the constriction of the isolated porcine coronary artery induced by Equinatoxin II (EqT II). EqT II is a polypeptide isolated from the sea anemone (Actinia equina, L.). Contractions induced by endothelin-1 (ET-1) were compared with the contractions induced by EqT II. The force of contraction induced by 100 nM EqT II reached only 30% of the force of contraction induced by 100 nM ET-1. EC50 for ET-1 was 5.14 nM, and for EqT II 101.1 nM. The effects of tezosentan, an endothelin ETA/B receptor antagonist, on contractions induced by either ET-1 or EqT II were compared. Tezosentan inhibited both ET-1 and, to a lesser extent, EqT II-induced contractions of isolated porcine coronary artery. Our present results confirm the involvement of endothelium in the EqT II-induced contractions of coronary arteries. The mode of action of tezosentan upon EqT II-induced contractions indicate that besides its pore-forming effect in the membranes, endothelium, and specifically endothelin-dependent mechanisms, are very important components of the toxin constrictory effects.

Animals↗