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Biomedical subjects

G Kovács

Publications and source records attributed to G Kovács.

At least 19 recordsLinked to original sources
PubMed1992

Inhibition of ACAT activity after 7-oxo-PGI2 treatment in cholesterol-fed rabbits.

It has been supposed that prostacyclin (PGI2) and its analogues have important antiatherogenic effects. The aim of this work was to test the effect of PGI2 and 7-oxo-PGI2- (a stable analogue of PGI2) (6) treatment on the acyl CoA: cholesterol-acyltransferase (ACAT) activity in the aortic wall of rabbits. The rabbits had been previously fed with cholesterol and treated with PGI2 and 7-oxo-PGI2 intravenously. Cholesterol feeding increased ACAT activity compared to the control group which was not fed with cholesterol: 16.84 nmol/mg prot./h and 10.03 nmol/mg prot./h, respectively. PGI2 treatment of the cholesterol fed group did not cause a significant decrease, while 7-oxo-PGI2 treatment significantly decreased aortic ACAT activity compared to the cholesterol-fed control group; 14.31 nmol/mg prot./h; 11.53 nmol/mg prot./h and 16.84 nmol/mg prot./h, respectively. The decrease found in the ACAT activity after PGI2 and 7-oxo-PGI2 treatment are new data for the protective effect of these agents against atherosclerosis.

Animals↗
PubMed1992

[Survey of the analysis of selegiline].

The characteristics of the selegiline active substance, identification tests, purity tests and the determinations of the active substance content are summarized in the paper. Fast, simple, selective reverse phase HPLC method is used for purity tests and active substance determinations. The validation of the determination of the active substance and the purity test is presented. The solvent residues were determined in vapour phase by the headspace method. A potentiometric acidi-alkalimetric titration, carried out in nonaqueous solution with the application of a titriprocessor is applied as an assay. A thermoanalytical method developed for the purity determinations is also published in this issue by Ladányi et al.

Chromatography, High Pressure Liquid↗
PubMed1991

[Systemic thrombolysis in acute obstruction of an artificial valve].

Prosthetic valve thrombosis is a characteristic, but fortunately not frequent complication of surgical valve replacement. Its occurrence may lead to haemodynamic catastrophe. Three cases involving prosthetic valve thrombosis are presented. Two patients suffered from thrombosis after tricuspid valve replacement (St. Jude Medical), while the third occurred after mitral valve replacement (Sorin). In the acute phase, systemic thrombolysis was initiated (2 MU Streptokinase during 22-28 hours). The obstruction of one of the tricuspid valves and the mitral valve was eliminated. Lysis of the other tricuspid valve was not complete, but it helped the patient to survive the acute phase until reoperation. Embolization occurred in the inferior extremity after thrombolysis of the mitral prosthetic valve, but it was cured. Two-dimensional and Doppler echocardiography (conventional and colour-coded) played an important role in the diagnosis of the obstruction and in the follow-up of the effectivity of thrombolysis. Systemic thrombolysis may be a lifesaving procedure in acute prosthetic valve thrombosis. In spite of the potentially dangerous complications, it has to be attempted.

Adult↗
PubMed1991

Interactive effects of neurohypophyseal neuropeptides with receptor antagonists on passive avoidance behavior: mediation by a cerebral neurohypophyseal hormone receptor?

The neurohypophyseal neuropeptides (Arg8)-vasopressin (AVP) and [pGlu4,Cyt6]AVP-(4-8) (where pGlu is pyroglutamic acid and Cyt is cystine) facilitate the retention of one-trial-learning passive avoidance behavior in rats when administered into the cerebral ventricle immediately after the learning trial. The fragment [pGlu4,Cyt6]AVP-(4-8) was considerably more effective than AVP. Oxytocin (OXT) and [pGlu4,Cyt6]OXT-(4-8) have the opposite effect and attenuate passive avoidance behavior also when administered into the cerebral ventricle after the learning trial. Again the fragment was more active than the parent molecule. The ancient arginine-containing neurohypophyseal hormone vasotocin in "high" doses (10ng) had a vasopressin-like effect and in "low" doses (0.1 ng) had an OXT-like effect on passive avoidance behavior. Because both vasopressinergic (V1) and oxytocinergic receptors have been demonstrated in the central nervous system, we asked whether specific antagonists of the V1, V2, and OXT receptor could antagonize the effects of these neuropeptides on passive avoidance behavior. The three antagonists were approximately equally active in blocking the effect of vasopressin, whereas the fragment [pGlu4]AVP-(4-8) and the high dose of vasotocin were more readily blocked by the OXT antagonist. The attenuating effect of OXT, the fragment [pGlu4,Cyt6]OXT-(4-8), and the low dose of vasotocin was markedly reduced by the OXT antagonist. This effect could also be reduced by pretreatment with the V1 antagonist but not with the V2 antagonist. These results suggest the existence of a separate neurohypophyseal hormone receptor complex in the brain affecting memory processes that differs from the peripheral V1, V2, and OXT receptor.

Animals↗
PubMed1991

A new antiinflammatory agent (EGIS-5645) without gastrointestinal side-effect.

The compound EGIS-5645 is a potent antipyretic agent possessing analgesic and antiinflammatory properties. The drug is active in antiinflammatory models such as carrageenin oedema and adjuvant arthritis. EGIS-5645 shows practically no gastro-ulcerogenic effect. The molecule does not inhibit either prostaglandin biosynthesis or soybean lipoxygenase enzyme activity.

Animals↗
PubMed1990

[Cardiolite (99m-Tc-isonitrile) SPECT studies in patients prior to coronary bypass surgery].

The authors studied with 99m-Tc Cardiolite (methoxy-isobutyl-isonitrile) SPECT examination the effect of coronary bypass operation on the myocardial perfusion. One week before and 3 weeks after the operation examinations were performed first with dipyridamol loading and 24 hours later in rest. The regional perfusion of the myocardium was studied on the basis of transversal section-pictures of corrected axis position. In the examinations preceding the operation the global sensitivity of the method was found to be 100%. In the demonstration of the structures of the ramus descendens 95%, of the ramus circumflexus and of the right coronary artery 100% sensitivity was reached. In postoperative examinations following the bridging of the ramus descendens anterior the improvement of the perfusion of the corresponding ventricular segment was found in 15/20 during the loading and in 7/8 cases following the bridging of the ramus circumflexus and right coronary artery. Improving perfusion was demonstrated in 17/20 and in 6/8 cases in rest. On the basis of the results the authors consider their method suitable for the study of the regional blood perfusion and for the examination of the changes taking place upon coronary bypass operations.

Aged↗
PubMed1989

Transitory increase in plasma FSH and LH levels induces early vaginal opening and corpus luteum formation in ovarian transplants of rats ovariectomized at 20 days of age.

The effect of a transitory increase in plasma FSH and LH levels on puberty has been investigated. Hormonal changes were induced by bilateral ovariectomy (OVX) at 20 days of age followed by implantation of two ovaries (donor animals 20-day-old) beneath the kidney capsule 1, 2 or 3 days later. In an other group of animals the two interventions were made in reversed order. Rats in which OVX was made first showed early vaginal opening. If ovarian implantation preceded OVX, these two interventions did not affect the time of vaginal opening. More than 1/3 of the ovarian implanted animals exhibiting early opening of the vagina contained corpora lutea three days after vaginal opening. FSH and LH levels of OVX + ovary implanted rats were from the third day on following implantations markedly different from the OVX controls and were in the range of intact or sham-operated rats. The present findings indicate that a transitory increase in plasma gonadotropin levels around twenty days of age may lead to precocious puberty.

Age Factors↗
PubMed1989

[Morphologic studies of emdomyocardial biopsy specimens].

Authors have studied 153 heart biopsies of 120 patients and results of 133 endomyocardial biopsies studied by light and electron microscopy are described. In addition to typical morphological picture of myocarditis, in majority of cases non-specific changes appearing also in idiopathic cardiomyopathy were observed and their ultrastructure is fully stated. Results are compared to relevant data of literature. Indications, informative value, practical and scientific research significance of myocardial biopsies are briefly overviewed.

Biopsy↗
PubMed1988

Hypothalamus and puberty.

The effect of a transitory increase in plasma FSH and LH levels during the prepubertal period on puberty has been investigated. Twenty-day-old rats had been bilaterally ovariectomized and 24 hr later they received two ovaries of infantile rats beneath the kidney capsule. These rats exhibited precocious puberty. Animals into which two additional ovaries had been transplanted first and the next day their own ovaries removed showed puberty at the same time as controls. Additional investigations provided evidence that the ovariectomized and ovary implanted rats plasma FSH and LH levels were in the control range four days after implantation. The findings support the assumption that the hypothalamic lesion-induced precocious puberty is due rather to a transitory enhanced release of gonadotropin releasing hormone by the lesion than to the destruction of sex-steroid sensitive structures inhibiting the release of gonadotropic hormones in prepubertal rats.

Animals↗
PubMed1988

Prevention by a stable prostacyclin analogue, 7-oxoprostaglandin I2 of the platelet loss during experimental cardiopulmonary bypass.

A great percentage of circulating platelets is lost through activation and aggregation during total body perfusion used in cardiac surgery. The effect on platelet count of a chemically stable prostacyclin analogue, 7-oxoprostaglandin I2 was investigated in anaesthetized dogs subjected to cardiopulmonary bypass of 120 min duration. In control (untreated) dogs the perfusion decreased the amount of circulating platelets by more than 60% of their initial value. This loss was completely prevented by i.v. infusion of the analogue (50 micrograms.kg-1.min-1) without affecting the haemodynamic state of the preparation. With the infusion of native prostacyclin at the same rate, a similar protective action was found to be associated with significant arterial hypotension. It was concluded that 7-oxoprostaglandin I2 is an useful pharmacological tool for maintaining physiological platelet counts and thus preserving haemostatic stability in open heart surgery.

Animals↗
PubMed1988

[Dermatofibrosarcoma protuberans. Results of radiosurgical therapy by photon and electron rays or fast neutrons].

The dermatofibrosarcoma protuberans, a rare entity of soft tissue sarcomas, is specified as a tumor of intermediate malignancy because of its marked tendency to form local recurrences. Regarding the prevention of local recurrences, the results of combined radiosurgical therapy (n = 13) could be improved in our patients by the application of fast neutrons (n = 6). Despite multiple previous operations for recurrences, a reliable prevention of local recurrences (average follow-up period 5.5 years) was achieved in all patients by neutron irradiation with focal doses of approximately 9 Gy. One patient with multiple macroscopic recurrences received two neutron series with 17 Gy. At seven years, she is still recurrence-free. We consider the postoperative irradiation of the dermatofibrosarcoma protuberans with fast neutrons following to primary tumor excision as method of choice for a reliable prophylaxis of local recurrences, because this method allows to dispense with major radical surgery.

Adult↗
PubMed1987

Cardioprotective effect of prostacyclin and 7-oxo-PGI2 in rats against chronic isoproterenol damage.

Isoproterenol (ISO) was injected in 5 mg/kg i.p. doses to rats, daily for two weeks. We evaluated the developed myocardial hypoxia and necrosis quantitatively by histological methods. To follow the time course of cardioprotection prostacyclin or 7-oxo-PGI2 were injected daily, i.p. 5, 30 min and 1, 2, 3, 4 hours before or after the ISO to groups of ten rats, respectively. Cardioprotection was defined as the reduction of necrotized areas and was expressed as percentage change compared to the control (saline treated) group. 1 microgram/kg PGI2 and 50 micrograms/kg 7-oxo-PGI2+ showed nearly equipotent cardioprotection (37.3-7.9% and 38.3-6.8%, respectively). The peak effect of both compounds appeared when injected prior to ISO in the 120. min but the action of 7-oxo-PGI2 was more prolonged. The different doses of prostacyclin analogs given after the ISO injection were ineffective with the exception of 50 micrograms/kg 7-oxo-PGI2 (29.75 +/- 5.2%).

Animals↗
PubMed1987

[Results of irradiation using different radiation sources in the treatment of malignant parotid tumors].

Patients with malignant parotid tumors were treated at two different centres with slightly ionizing radiation (110 patients) and neutron therapy (15 patients). The treatment results are compared. The principles of comparison applied in this analysis are identical. The histologic classification was made according to the W.H.O. recommendation of 1972 and the staging according to Becske. Local tumor control is the criterion applied in the comparative assessment of both methods. The analysis has shown that there is no significant difference in the treatment results within the individual stages of tumor's advancement after application of an orthovolt therapy and a telecobalt therapy. Patients treated in early stages (stages I and III) had a substantially higher rate of local tumor control (72%) than patients in advanced stages (46%, stages III and IV). A more favorable treatment results was achieved by neutron therapy in all stages of tumor's advancement. In this case the rate of patients with local tumor control (87%) was significantly higher than after radiotherapy with slightly ionizing radiation (46%).

Adenocarcinoma↗