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Biomedical subjects

G Temes

Publications and source records attributed to G Temes.

At least 19 recordsLinked to original sources

[Diagnostic and therapeutic problems of sponaneous retroperitoneal hematoma].

The authors report four cases of spontaneous retroperitoneal haematomas, which occurred in their department during a half year period. The patients were admitted from different internal medicine departments. They had anaemia, and bleeding with unknown origin and localisation, and were in a bad condition. Three patients could be suitable for operation after general preparation. One of these patients died and another one died without operation. Two of them went home after recovering. The patients were transferred to surgical department on average three days after the symptoms developed. Hypoprothrombinaemia was the reason for bleeding in three cases. One patient got overdosed Syncumar, and two patients suffered from alcoholic cirrhosis who had other serious diseases as well. The authors found that the fourth patient, who had the gluteal arterial rupture with inexplicable origin, also had hypoprothrombinaemia. It is very difficult to diagnose these disease. Bleeding always has to be taken into consideration, if the patients have liver disease, or any type of coagulopathy, or take some anticoagulant medicine. The blood test examinations, ultrasound, CT, MR, angiography, laparoscopy can be helpful in the diagnosis of these cases.

Acenocoumarol↗

Cardioprotection during heart ischemia-reperfusion.

Oxygen reactive species play a significant role in reperfusion tissue damages. In this study we aimed to investigate the mechanisms of injury regarding changes of neutrophil function. In our experiments the left descending coronary artery (LAD) was ligated in Beagle dogs for 1 hour followed by one hour reperfusion. Animals were divided into two groups: Group I. dogs (n = 10) served as control: Group II. the animals (n = 10) were treated by cardioprotective drug Bisaramil. Peripheral blood samples were taken for neutrophil isolation before operation and subsequent reperfusion (5 min, 1 hour). The stimulated superoxide radical generating capacity of polymorphonuclear leukocytes (PMN) was measured. The lipid peroxidation (MDA), amount of reduced glutathione (GSH) and activity of superoxide dismutase (SOD) were measured in non-ischemic and ischemic parts of left ventricle. There was no significant changes either in control or in treated animals in respect to changes of neutrophil radical production after one hour LAD ligature, however there was a significant discrepancy (p < 0.001) between control and treated animals following a 1 hour reperfusion. The values of MDA in the ischemic-area increased characteristically in the Group I. parallel with decrease of scavenger GSH and SOD. In contrast in Group II., where depleted PMN radical production was observed endogenous scavengers were preserved on a higher level. In summary we can conclude that diminished superoxide radical production of circulating neutrophils during reperfusion has beneficial effects on tissue injury caused especially by free radicals.

Animals↗

Effects of bisaramil on coronary-occlusion-reperfusion injury and free-radical-induced reactions.

The aim of this study was to determine whether bisaramil-an antiarrhythmic compound under clinical investigation-influences the reperfusion-induced arrhythmias and biochemical parameters characterizing occlusion-reperfusion-induced free-radical reactions. The left descending coronary artery (LAD) was occluded for 60 min in anaesthetized dogs followed by one hour of reperfusion. Blood samples were taken at different times of the occlusion and reperfusion for the determination of plasma concentration of malondialdehyde (MDA), reduced (GSH) and oxidized glutathione (GSSG); furthermore of the activity of catalase and superoxide dismutase (SOD). Free-radical generating capacity of polymorph neutrophil granulocytes (PMN) was also measured. At the end of the experiments heart tissue samples were excised from the injured areas and from the intact part of the left ventricular muscle. In tissues samples the concentrations of MDA and GSH and the activity of SOD were determined. Bisaramil was given as an i.v. bolus injection at a dose of 2 mg kg-1 several minutes prior to the end of LAD-occlusion; then the administration was repeated in the 30th minute of reperfusion. In the control group (10 dogs) ventricular fibrillation (VF) occurred in seven cases which resulted in death in three. In the bisaramil-treated group, however. VF was seen in three cases and no death was recorded. Bisaramil inhibited the elevation of the plasma concentration of MDA and GSSG during the reperfusion and abolished the decrease in the plasma concentration of GSH during the occlusion and reperfusion. The activity of SOD and catalase in plasma was much better preserved in the bisaramil-treated group then in the controls. Bisaramil significantly inhibited the increase of the superoxide-radical generating capacity of PMNs during the reperfusion. The data obtained from myocardial tissue samples supported the cardioprotective effect of bisaramil. The biochemical investigation of ischemic-reperfused myocardium showed that bisaramil promoted preservation of SOD-activity and of tissue glutathione. Results of this study clearly showed that bisaramil has a significant effect on ischemiareperfusion injury. Besides its inhibitory effects on ischaemia-reperfusion induced arrhythmias it has a special benefit in influencing free-radical mediated damage leading to better preservation of membranes and to limitations of irreversible cell injuries.

Animals↗

Alterations in malondialdehyde concentration of jugular vein blood following transient brain ischemia. The effect of lactic acidosis.

Ischemia was induced for 10 min with a subsequent 60-min reperfusion and the changes of the malondialdehyde (MDA) concentration in the blood samples from the jugular vein were investigated in normo- and hyperglycemic dogs. Selective brain ischemia was evoked by the increase in cerebrospinal fluid (CSF) pressure. The experiments were carried out in 4 experimental groups. In sham operated animals (Group I) the blood MDA concentration did not change. The venous blood MDA content significantly elevated for 10 min after the start of reperfusion in normoglycemic animals (Group II). To study the effect of acidosis during ischemia and reperfusion on brain lipid peroxidation (LP) processes 1 and 2 g/kg glucose infusion was used in Groups III and IV. As an effect of ischemic lactic acidosis due to hyperglycemia the elevation of MDA concentration in the jugular vein blood was higher and it lasted longer than in the cases of normoglycemia. This finding supports the hypothesis that free radical reactions and LP processes play an important role in the enhanced brain damage caused by tissue acidosis.

Acidosis, Lactic↗

Influence of protective drugs on the elevation of extracellular potassium ion concentration in the brain during ischaemia.

Influence of drugs on the changes of extracellular potassium ion concentration in the brain during total cerebral ischaemia was investigated. The aorta of the dogs was clamped twice with an intermittent reperfusion period of 60 min. In control experiments no significant difference was found in the elevation of extracellular potassium ion concentration of the brain during the first and second clampings. In the present study drugs were administered 10 min prior the second aorta occlusion. Verapamil in a dose of 0.125 mg/kg proved to be ineffective. Piridoxilate in a dose of 10 mg/kg and piracetam in a dose of 100 mg/kg delayed to a small extent the potassium outflow. The following drugs enhanced significantly the duration before the steep increase of potassium ion outflow: phenytoin in a dose of 10 mg/kg by 31.8 sec (p less than 0.01), ethyl-butyl-thiobarbital in a dose of 15 mg/kg by 30.2 sec (p less than 0.05), and lidocaine in a dose of 100 mg/kg by 115.8 sec (p less than 0.01). Comparing present results to our earlier data (obtained after 50 sec ischaemia) it can be concluded, that these protective influences become more effective during longer ischaemic period (2-5 min), when lidocaine, phenytoin and ethyl-butyl-thiobarbital were used. Moreover, in spite of the observation seen during shorter ischaemia, even piridoxilate and piracetam exerted some degree of protective effect. No such effect of verapamil could be detected in the present experimental model.

Animals↗

Influence of protective drugs on the EEG during short-term transient ischaemia.

Influence of drugs on the cessation time of the brain electrical activity (resistance time) during total cerebral ischaemia evoked by clamping of the aorta for 50 sec; on the duration of its reappearance during reperfusion (restitution time) and on the background activity of EEG were studied. The experiments were carried out in 7 groups. Each group contained 5 animals. Nine clampings with intermittent reperfusion periods of 10 min were performed in each animal. One group served as control. In the remaining ones after the first three clampings the animals were given Glyo-6, Nootropil, Verpamil, Epanutin, Inactin or Lidocain. The resistance and restitution times measured in the control group as well as the reproductibility of the power spectrum values of the EEG provided evidence for the stability of the model. Glyo-6 in a dose of 10 mg/kg, Nootropil in a dose of 100 mg/kg or Verpamil in a dose of 0.125 mg/kg did not alter the above-mentioned parameters. As an effect of the administration of Epanutin in a dose of 10 mg/kg, the resistance time increased slightly, whereas restitution time decreased significantly. Administration of Inactin in a dose of 15 mg/kg, or Lidocain in a dose of 100 mg/kg increased considerably resistance time for a period of about one hour. The results indicate that in the initial phase of ischaemic brain damage both the cessation of EEG activity and the restitution during reperfusion after short-term occlusion of the circulation can be influenced favourable with drugs which decrease cerebral metabolism, inhibit synaptic transmission and have membrane stabilizing effect.

Animals↗

Myocardial protection by antioxidant during permanent and temporary coronary occlusion in dogs.

In an ischaemic heart model the lipid peroxidation, scavenger state and ultrastructure were studied, to determine the action of a new antioxidant of dihydroquinoline type (MTDQ-DA). In dog experiments, the left descending coronary artery (LAD) was ligated permanently (30 minutes, 1, 2 or 3 hours) or temporarily (30 minutes, 1 or 2 hours of ischaemia followed by 1 hour of recirculation). The experimental protocol involved two groups: control animals without antioxidant treatment and animals treated with antioxidant infusion during the ischaemic and reperfusion period. In both groups, the thiobarbituric acid reactive product, the malondialdehyde (MDA), reduced glutathione (GSH) and superoxide dismutase (SOD) were measured, to illustrate the injured or scavenged state of the membrane system. In nontreated animals the permanent and temporary LAD increased the MDA content, decreased GSH concentration (mainly during reperfusion) and reduced SOD activity. Treatment with MTDQ-DA diminishes the characteristic biochemical changes. According to ultrastructural investigations, irreversible alterations (Ca deposits in the mitochondria, disruption of intramitochondrial membranes, hypercontraction bands) occurred only in the control group. Anti-oxidant therapy is able to reduce the myocardial damages both quantitatively and qualitatively.

Animals↗

Promising reduction of ventricular fibrillation in experimentally induced heart infarction by antioxidant therapy.

Studies were undertaken using a synthetic free radical scavenger (MTDQ-DA) on regional ischaemic dog hearts; it was found that the rate of malignant ventricular arrhythmias and fibrillation after coronary ligature unexpectedly decreased. According to experiments on 22 dogs, the intravenous MTDQ-DA therapy decreases the unfavourable ECG consequences of left anterior descending branch ligature: already 5 to 10 minutes after drug administration the ST segment elevation, the QT interval lengthening and the occurrence of ventricular extrasystoles and salvos are diminishing. The so-called epicardial ST map ameliorates rapidly. MTDQ-DA as a blocking agent of free radicals is able to prevent the irritative stimuli around and in the border zone of an infarct, has a vigorous anti-arrhythmogenous effect and greatly reduces the electric heterogeneity. These unexpected results may lead to a promising therapy for the acute heart infarction.

Animals↗

Possibility of brain recovery after electrically induced cardiac arrest and reanimation in dogs.

The changes of aortic blood pressure (BP), carotid artery flow (CAF), power spectrum of analysed EEG, neurologic deficit and survival rate were determinated in dogs after experimental cardiac arrest of different duration. Following artificially induced ventricular fibrillation of 1, 4, 10, 12 and 15 min duration successful cardiopulmonary resuscitation was performed in 30 experimental animals. Alterations of power spectrum during and after reanimation procedures, severity of the neurologic state and the survival rate deteriorated in parallel with the increasing duration of circulatory stop. Advantageous effect of direct heart massage could be demonstrated by the measuring circulatory parameters. Following a 15 min fibrillation, all animals were lost in a few hours despite the successful restoration of circulation and ventilation. Considering the various experimental and clinical conditions experimental cardiac arrest lasting for 12 min seems to be useful in extrapolating the results to human cases. The suggested model allows to study the brain function recovery after circulatory stop and resuscitation.

Animals↗

Induced precipitation of calcium-oxalate crystals and its prevention in laboratory animals.

Induced precipitation of Ca-oxalate crystals and the possibility of its prevention were studied in dogs. In the first phase of the experiments precipitation of Ca-oxalate crystals in canine renal tubules was induced by intraperitoneal administration of Na-glyoxylate. Preventive medication (lipoic acid, vitamin B1, Milurit), applied in the second phase, resulted in a significant depression of induced precipitation. The successful experiments serve as a basis for clinical research aimed at a preventive medication of recurrent Ca-oxalate stone formation.

Animals↗

Changes during ischaemia in extracellular potassium ion concentration of the brain under nitrous oxide or hexobarbital-sodium anaesthesia and moderate hypothermia.

Changes in the time lag until a steep increase in cerebral extracellular potassium ion concentration occurring during total ischaemia caused by clamping of the aorta were investigated in dogs. The results indicate that during two subsequent clamping of the aorta in the same animal the time lag between the start of ischaemia and the steep increase in potassium ion concentration (1) hardly changed during nitrous oxide anaesthesia, i.e. from 2.09 +/- 0.31 to 2.22 +/- 0.51 min; (2) as a response to the administration of hexobarbital-sodium the steep increase took place 0.50 +/- 0.37 min later, i.e. 2.89 +/- 0.74 min after the administration of the drug and then, at the second clamping, 2.39 +/- 0.71 min; (3) during a 1 degree C decrease in body temperature the steep increase took place 0.29 +/- 0.05 min later. From the values of cerebral extracellular potassium ion concentration during ischaemia the conclusion might be drawn that hypothermia serves as the principal factor in the protection of the ischaemic brain tissue; meanwhile, also hexobarbital-sodium has a significant though somewhat smaller protective effect.

Anesthesia↗

Correlations between the quantity of cerebral flow, brain surface pO2, and EEG in the dog.

Complete cerebral ischemia was carried out in 19 dogs by repeated occlusion of the large neck arteries. The interruption of cerebral blood flow (CBF) was controlled with the electric silence recorded on EEG and the rapid fall of brain surface oxygen tension (bspO2). A critical flow was determined in each experiment by release of clamping of one artery (left carotid artery), which seemed effective not only to stop the decrease of bspO2 but also to ensure the reappearance of EEG waves. This crucial value of carotid artery flow (CAF) was 49 ml/min and 38 ml/min after the first and second occlusions, respectively. The EEG changes during different phases of experiments were stored on magnetic tape and analyzed by computer. The distribution of the analyzed power spectrum of EEG provides a special characterization of brain function. Strict correlations are found between the actual blood flow and the changes of EEG and bspO2. Either alteration of the recorded two parameters can accurately reflect the possibility of brain recovery during and after short-lasting ischemia.

Animals↗

Circulatory and EEG changes during resuscitation in experiments.

In anaesthetized dogs blood pressure (BP), carotid artery flow (CAF), oxygen tension of arterial blood (paO2) and brain surface (bs-pO2), ECG, frequency analyzed EEG were measured and/or recorded. The changes in these parameters were detected before and during ventricular fibrillation with external and direct heart massage as well as after defibrillation. Comparisons were made between the effect of oxygen and room air ventilation. The ratio of successful resuscitation was 88% with direct heart massage and O2 respiration, 76% with external thoracic massage and O2 ventilation, and 68% with external massage combined with room air respiration. The highest BP and CAF could be achieved with direct heart massage. The results suggest that the minimal requirement for success is to achieve a BP of 5 kPa (40 mmHg) and 13 ml/min CAF. In dogs with large and stiff thorax this minimal pressure and flow could not be attained. During effective massage with room air ventilation brain surface pO2 increases moderately, but with O2-respiration it returns to normal. Small or no changes in bs-pO2 indicates unfavourable prognosis. The start bs-pO2 elevation coincides with the reappearance of the first EEG waves, while pO2 increase on the brain surface precedes the normalization of EEG.

Animals↗

Primordial conditions of successful resuscitation: experimental study.

In anesthetized dogs blood pressure (BP), carotid artery flow (CAF), oxygen tension of arterial blood (PaO2) and brain surface (bs-PO2), ECG, and frequency-analyzed EEG were measured and recorded. The changes in these parameters were detected in the control state and during ventricular fibrillation with external and direct heart massage as well as after defibrillation. Comparisons were made between the effect of oxygen and room air ventilation. The degree of successful resuscitation was 88% with direct heart massage and O2 respiration, 76% with external thoracic massage and O2 ventilation, and 68% with external massage combined with room air respiration. The highest BP and CAF could be achieved with direct heart massage. The results suggest the following: the minimal requirement for success is to achieve a BP of 5 kPa 40 mmHg and 13 ml/min CAF. In cases of dogs with a large and stiff thorax, this minimal pressure and flow cannot be ensured. During effective massage with room air ventilation, the brain surface PO2 increases moderately, but with O2-respiration it returns to normal. Small or no change in brain surface PO2 indicates an unfavorable prognosis. The start of brain surface PO2 elevation coincides with the reappearance of the first EEG waves, but the bs-PO2 increase precedes the normalization of EEG.

Animals↗

Changes of electrical activity and surface potassium concentration of the brain during ischaemia and reperfusion.

Electrical activity and surface potassium ion concentration of the dog brain showed characteristic changes during acute ischaemia caused by 1-to 5-min occlusion of the aorta and during subsequent reperfusion. The present results show that (1) brain surface potassium concentration increases slowly during ischaemia, however, a sudden elevation ensues 3.07 +/- 1.03 min after the start of occlusion; (2) the higher the arterial glucose level is, the later this steep elevation of potassium concentration develops; (3) restitution of electrical activity of the brain during reperfusion, after an ischaemic period when potassium concentration was significantly elevated, occurred significantly later than during reperfusion after an ischaemic episode when the increase of surface potassium concentration was only moderate.

Animals↗

Structural changes in the heart due to mechanical perfusion.

Acute myocardial damage such as epicardial, intramural and subendocardial haemorrhages and oedema are known to occur after mechanical perfusion. The results of animal experiments showed that local circulatory disturbances (hypoperfusion, hypoxia) due to mechanical damage of the blood (erythrocyte aggregation, denaturation) and or lasting hypoperfusion (microcirculatory hypoxia) are responsible for the acute lesions. In addition, the results offer a morphological explanation for the postperfusion heart failure.

Animals↗

Causes and consequences of circulatory changes in renal transplants. I. Angiographic studies.

Selective angiography post mortem and in vivo, respectively, has been performed in canine kidneys (isolated, autografted or left in situ) for the study of the renovascular changes caused by different perfusates and by reperfusion. The results indicate that inadequate heparinization, the composition of the perfusate, imperfect surgical techniques and even restoration of circulation to the kidney itself, may produce roentgenologically demonstrable renovascular damage the causes and consequences of which are unrelated to those of the closely studied and adequately interpreted phenomena of graft rejection.

Angiography↗