PubMed Health⌕ Search

Biomedical subjects

L Kónya

Publications and source records attributed to L Kónya.

At least 19 recordsLinked to original sources
PubMed1992

The effect of superoxide dismutase in the myocardium during reperfusion in the dog.

The aim of the study was to investigate the pathological role of free radicals during myocardial reperfusion. Low (0.5 mg/kg body weight) and high doses (5 mg/kg) of superoxide dismutase (SOD) were infused into the left atrium of mongrel dogs for 4 min starting 29 min after ligation and 1 min before reperfusion of the left anterior descending coronary artery (LAD). Arterial blood pressure, heart rate, electrocardiogram, and the regional contractile force of the left ventricle were monitored throughout the ligation (30 min) and reperfusion periods (20 min). Concentrations of creatine kinase (CK) and malondialdehyde (MDA) in the coronary sinus blood were determined before (0 min) and during ligation (15 and 25 min) and during reperfusion of the LAD (2, 7, and 20 min). In other groups of dogs, the effect of the two doses of SOD on epicardial blood flow was investigated during ligation and reperfusion by the measurement of epicardial temperature using a thermocardiograph. Experimental subjects were mongrel dogs of either sex (n = 25), weight 10-35 kg. Compared to controls (mean +/- SEM, 43.1 +/- 1.2; n = 7), the number of ventricular extrasystoles during the first 5 min of reperfusion was significantly (p < .001) decreased in dogs treated with the high dose (15.01 +/- 2.14; n = 5), but not in those receiving the low dose of the drug (34.6 +/- 5.66; n = 5). The concentrations of CK increased gradually until the end of reperfusion without differences among the different groups. Plasma MDA was the highest in control dogs 7 min after reperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

[The role of oxidative stress, caused by amiodarone, in the side effects of the drug].

It was supposed that free radicals are produced during the metabolism of amiodarone and involved in the mechanism of the drug's side effects. In vitro and in vivo experiments were performed in rats to check this hypothesis. We verified that amiodarone generated free radicals in vitro by chemiluminometric method. The light emission induced by amiodarone was inhibited by dihydroquinoline type antioxidants CH 402 and MTDQ--DA in a dose dependent manner. The malondialdehyde content, --one of the end products of lipid peroxidation--was increased by in vivo amiodarone administration in the serum and liver homogenate of rats. Amiodarone treatment increased significantly the NADPH and Fe3+ induced lipid peroxidation in rat liver microsomal fractions. The protective effect of antioxidants, MTDQ--DA and silibinin were ambiguous in these in vivo "short term" experiments.

Amiodarone↗
PubMed1991

Study of the effect of superoxide dismutase on acute renal failure in dogs.

Warm ischaemia was provoked by occlusion of the left renal artery in dogs narcotized with Nembutal and it was studied whether a small (0.5 mg/kg body weight /n = 6/) or a large dose (5 mg/kg body weight /n = 7/) of superoxide dismutase (SOD) improves renal function during 90 min reperfusion, compared to the control group (n = 6). In the first period after release of occlusion (min 0-15) the GFR and cPAH values reached 10-20% of those in the contra lateral kidney with normal circulation. The GFR and cPAH values as well as urine flow, sodium and potassium excretion were not different in the three groups. Renal function significantly improved in all groups during reperfusion. At the early stage of reperfusion the malondialdehyde (MDA) concentration exceeded that before occlusion. Such an increase could not be seen when superoxide dismutase (SOD) treatment was applied. Our results show that SOD treatment does not improve renal function at the early stage of acuterly stage of acute renal failure of ischaemic origin.

Acute Kidney Injury↗
PubMed1991

Exogenous superoxide dismutase uptake by the myocardium and kidney in an ischaemic reperfusion model in dogs.

The renal and cardiac tissues of dogs were examined with autoradiographic method in ischaemic reperfusion trials with the aim of studying the access of exogenous superoxide dismutase (SOD) enzyme to the cells. Penetration of SOD into the cells was demonstrated. The enzyme showed special affinity to the mitochondira and myofilaments in the myocardium and it was seen both in the glomeruli and the tubules in the kidney. In both organs the uptake of the enzyme was most abundant in the ischaemic regions than in tissues with intact circulation.

Animals↗
PubMed1990

[Malignant histiocytosis associated with chronic hepatitis].

A case of malignant histiocytosis successfully treated with splenectomy and chemotherapy is presented. 33 months after surgery the patient's overall condition is satisfactory. The result is attributed to the fact, that in the time of the operation there was no systemic proliferation. The concomitantly present chronic viral hepatitis was worsened by the treatment.

Adult↗
PubMed1990

Effect of free radicals in ischaemic renal failure in the dog.

After a 30-minute control period ischaemia was evoked in dogs under Nembutal (30 mg/kg, i.v.) anesthesia, by clamping the left renal artery for 45 minutes. This was followed by a 90-minute reperfusion period when diuresis, GFR, PAH clearance, sodium and potassium excretion, malondialdehyde level in the plasma of the renal vein and SOD enzyme activity of the erythrocytes in renal venous blood were determined. Besides the control group (n = 6), the following treated groups were investigated: 1. Allopurinol (n = 7) in a dose of 100 mg/kg, given orally for two days, 2. Silibinin (n = 6) in a dose of 4 mg/kg/hour, given into the renal artery, 3. MTDQ-DS (n = 6) in a dose of 150 mg/kg/hour, given intravenously. 4. SOD (n = 4) 4 mg infusion (initiated 1 minute prior reperfusion). In the first 15-minute period following reperfusion GFR was 21%, cPAH 29% and sodium and potassium excretion 67 and 42% of the values of the contralateral kidney, respectively. Renal function improved gradually during the 90 minutes of reperfusion, and the above-mentioned parameters reached 59, 57, 65 and 76% of the corresponding control data. Increase of malondialdehyde level in the venous blood of the kidney during reperfusion might have been indicative of the production of free radicals; the difference, however, was not significant statistically. The administrations did not lead to considerable change in any of the parameters investigated. No difference could be demonstrated by histological methods between the kidneys of the treated and untreated animals. The compounds studied are thought to be free radical scavengers; in the present work, however, no protective effect could be demonstrated.

Acute Kidney Injury↗
PubMed1989

[Diffuse intestinal malignant lymphoma].

The authors describe a patient with malignant lymphoma presenting with clinically severe malabsorption due to diffuse involvement of the small intestine and with intestinal obstruction. The histologic diagnosis was based on the association of (1) diffuse involvement of the small intestine showing lymphoid tissue expansion and (2) a non-classified form of highly malignant lymphoma. After surgical resection of a stenotic part of the small intestine, abdominal irradiation therapy was done, and the patient improved.

Adult↗
PubMed1986

The role of DTNB light chain in the contractile properties of skeletal muscle.

The mechanical and molecular dynamical properties of the glycerinated muscle fibres from m. psoas of rabbit were investigated after treatment with 5,5'-dithiobis/2-nitrobenzoate (DTNB). After DTNB treatment the fibre bundles shortened and exerted force in ATP-relaxing solution. The rate of the ATP hydrolysis in relaxation-inducing medium increased significantly after DTNB treatment, and simultaneously the amount of the LC2(DTNB) light chain decreased to 40 per cent of the original value measured by gel electrophoresis. The electron paramagnetic resonance spectra of muscle fibres labelled with maleimide spin label after DTNB treatment exhibited high degree of order of label in rigor, but this order decreased after shortening. The experiments support the assumption that, in vertebrate skeletal muscles, besides the troponin-tropomyosin regulation system which developed later in evolution, the LC2 light chain should maintain some regulatory properties.

Adenosine Triphosphatases↗
PubMed1985

Effect of DTNB-treatment on Ca++-sensitivity of superprecipitation and ATPase activity of actomyosin.

A light chain of 18 000 daltons of native actomyosin isolated from rabbit skeletal muscle was removed by DTNB-treatment. Investigated were the differences in superprecipitation and ATPase activity of LC2-deficient and control actomyosin. The superprecipitation of control actomyosin develops in two phases, with high amplitude and kinetics dependent on the Ca++ concentration. On the other hand, superprecipitation of treated actomyosin develops in a single phase, with low amplitude and a kinetics independent of the Ca++ concentration. The partial lack of LC2 leads to the loss of Ca++-sensitivity of ATPase activity. On the basis of the results, LC2 has been assumed to fix that conformation state of myosin heads which is required for the functioning of the troponin system on the one hand, and a cooperation between myosin heads on the other. The regulatory function of LC2 is manifest in controlling the actin-myosin-ATP interaction, at the activated state of the troponin system, in an extent depending on the actual Ca++ concentration.

Actomyosin↗
PubMed1984

Idiopathic dilatation of the right atrium. A case report.

Idiopathic dilatation of the right atrium in a young woman is reported. Thoracotomy was performed for suspected pericardial cyst. Intraoperative findings suggested idiopathic right atrial dilatation, which was histologically confirmed. Two years after partial resection of the dilated right atrial wall the patient is doing well. Management of asymptomatic idiopathic dilatation of the right atrium should be medical, surgery being reserved for patients with symptoms.

Adult↗
PubMed1984

The effect of adenosine diphosphate on the interaction of actin-myosin-adenosine triphosphate.

It was shown in experiments made on natural actomyosin of rabbit skeletal muscle that ADP possesses direct and indirect effects on superprecipitation. The presence of ADP increases the turbidity of the actomyosin suspension. An optimal ATP/ADP ratio may help the development and existence of a PC conformer of actomyosin corresponding to a myosin-ADP-actin-myosin-ATP complex. In this complex the extent of actin-activation is controlled by the cooperativity between the two myosin heads which, on the other side, may regulate in vivo the optimal transformation of the chemical energy of ATP for mechanical work.

Actins↗
PubMed1983

Step-like superprecipitation of actomyosin.

The superprecipitation of natural actomyosin prepared from rabbit skeletal muscle shows a step-like character under physiological conditions (KCl 0.14 M, ATP 0.001 M). Alkali metal cations applied in the same (0.14 M) concentration cause a delay according to the Hofmeister sequence, while in their presence the step-like character of superprecipitation is retained. Reduction of the Ca2+ concentration also causes a delay in the development of superprecipitation, but its step-like character is retained in this case, too. Increasing the Mg2+ concentration in the medium causes a delay or disappearance of superprecipitation and modifies it to occur in a single step. It is assumed that the actions studied exert, their effect in a combined way actin directly or indirectly on the interaction of actin and myosin.

Actomyosin↗
PubMed1983

The importance of changes in ATP and ADP concentrations in the development of the phasic superprecipitation of actomyosin.

It has been shown previously that at physiological K+-concentrations the development of superprecipitation has a phasic character. Studying the reason of this effect, by the use of beta-32P-ADP ATP-regeneration from ADP was detected during the first phase of superprecipitation. Myokinase activity of actomyosin may be responsible for the appearance of this first phase of turbidity change of actomyosin suspension. Myokinase contributes to the stabilization of an ATP/ADP ratio within narrow limits. During the first phase of superprecipitation the ATP/ADP ratio is between these limits, while during the second phase the ratio has a low value. This phasic evolution of superprecipitation is, probably connected with the physiological functional state of the muscle (contraction or rigour).

Actomyosin↗
PubMed1980

Effect of primycin on some electric properties of the frog skeletal muscle.

The effect of primycin, a guanidine-type antibiotic was studied on the electric properties and 42K+ uptake of the frog sartorius and semitendinosus muscle. Both in normal and choline chloride Ringer solution, primycin evoked a concentration and time dependent depolarization of the surface membrane of the muscle. This depolarization was significantly increased by Na ions. Primycin treatment was shown to evoke a dose-dependent decrease of the depolarization induced by 20 mM K+-Ringer. When the muscles were incubated in a Ringer solution containing choline chloride, during an incubation period of 30 min the uptake of 42K+ was decreased to 12% upon the exposure to 5 x 10(-6) mol primycin as compared to the control value. As the primycin-induced depolarization increased, the shape and amplitude of the action potentials elicited by square-wave electric impulses were altered and decreased, respectively. In sodium isaethionate Ringer 1--2 x 10(-6) M primycin induced a slow depolarization resulting in firing potentials. The results suggest that primycin depolarizes the surface membrane exclusively through the blockade of the resting K+ channels, the other phenomena being the results of this depolarizing effect.

Action Potentials↗
PubMed1979

[Complications of aortoiliac surgery and their postoperative therapy].

Experience in early postoperative treatment of 249 patients who had been subjected to aortoiliacal vascular surgery is reported. The therapeutic principles are outlined and the complications are reviewed. For the prevention of infectious complications the patients are given antibiotic protection, are fed parenterally till passage starts and, to avoid threatening postoperative hypoxaemia in the case of more severe respiratory disorders, prophylactic respiratory therapy is applied, and small doses of heparin are administered to prevent thrombosis. Taking into consideration the high incidence of complications and the advanced age of the patients, it is important to keep these in the intensive ward during the early postoperative period.

Adult↗