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Biomedical subjects

M Németh

Publications and source records attributed to M Németh.

At least 37 records · Page 2Linked to original sources
PubMed1991

Hyperlipemia and hyperlipoproteinemia [HLP] screening among the children from premature myocardial infarction risk families.

Serum lipids and lipoproteins were investigated in the premature myocardial infarction (PMI) risk families before 45 years of age with the aid of screening for hyperlipemia and hyperlipoproteinemia (HLP): in the case of 174 persons from Csongrád County from the Departments of Internal Medicine I and II and of 42 patients (fathers) suffering from PMI and their 79 "high risk" children from Heves County. In the investigated three groups of "high risk" children the genetically determined antiatherogenic HDL-Ch level diminished in 34.8, 52.3, 40.5 per cent. Significant negative correlation was detected between the serum HDL-Ch and beta-lipoprotein; significant positive correlations were found between the HDL-Ch and the serum lipase activity; between the beta-lipoprotein and the phospholipid level; significant negative correlation was proved between the HDL-Ch and the phospholipid level in the group of PMI patients and their offsprings. The Ch/Tg, and the HDL-Ch ratios were significantly diminished in the PMI patients' group against the risk children' group, while the Ch/HDL-Ch rate was significantly elevated.

Adolescent↗
PubMed1991

Effects of simulated ischaemia on the electrical activity of ventricular myocardium in the presence of antiarrhythmic drugs.

The effects of a nutrient solution simulating the 'ischaemic milieu' (combined hyperkalaemia, hypoxia and acidosis) on the electrical activity of rabbit isolated ventricular myocardium were examined in the absence and presence of antiarrhythmic drugs. In such a simulated ischaemia the resting membrane potential, the rate of depolarization (Vmax) and the action potential duration (APD) were all diminished with a resultant decrease in conduction and a shortening of the effective refractory period (ERP). Sotalol, a Class 3 antiarrhythmic drug (5 x 10(-6)-10(-5) M/l) afforded a marked protection against the "ischaemic" abbreviation of the ERP and APD. To a much lesser extent, the same applied to propafenone, a predominantly Class 1C antidysrhythmic agent (1.65-3.3 x 10(-6) M/l). The 'ischaemia'-induced depression of Vmax was increased considerably by propafenone and diminished slightly by sotalol. The results are in keeping with the efficacy of propafenone and sotalol in ventricular arrhythmias of ischaemic origin and also with the proposal that the major mechanism by which propafenone inhibits postinfarction ventricular arrhythmias is a further depression of ischaemic myocardial cells resulting in conduction block of the reentrant wave front.

Action Potentials↗
PubMed1990

Short incubation with 7-oxo-prostacyclin induces long lasting prolongation of repolarisation time and effective refractory period in rabbit papillary muscle preparation.

STUDY OBJECTIVE - To determine whether the long lasting protection from early postocclusion and reperfusion arrhythmias induced by 7-oxo-prostacyclin is due to an anti-ischaemic effect alone or in combination with direct membrane effects. DESIGN - The study was performed on electrically stimulated isolated rabbit papillary muscle preparations with or without incubation with a stable prostacyclin analogue, 7-oxo-prostacyclinephedrine (7-oxo-PgI2). In some experiments, rabbits were pretreated with 7-oxo-PgI2. MEASUREMENTS and RESULTS - Marked prolongation of action potential duration (APD90) and effective refractory period developed 2 h after 20 min incubation with and subsequent washout of 7-oxo-PgI2, 1.1 X 10(-8) mol.litre-1. The same occurred if incubation with 7-oxo-PgI2 was maintained throughout the experiment. The only other change was a small diminution in amplitude of the action potential. During the 20 min incubation period neither APD90 nor effective refractory period was affected and only a transitory increase in the maximum rate of depolarisation, disappearing after washout, was seen. During the 4 h observation period there were no changes in the control preparations. The long lasting electrophysiological changes induced by 7-oxo-PgI2 were not affected by 60 min incubation with indomethacin, 2.8 X 10(-6) mol.litre-1. Pretreatment of rabbits with 7-oxo-PgI2, 50 micrograms.kg-1 intramuscularly, 48 h before the experiments prolonged effective refractory period v untreated controls. CONCLUSIONS - 7-oxo-PgI2 induces prolongation of APD90 and effective refractory period in adequately oxygenated normal papillary muscles as well as in ischaemic hearts. Therefore a direct membrane effect may contribute to its antiarrhythmic action, as well as an indirect anti-ischaemic effect. Such a direct effect is unlikely to be related to activation of the degradation products of the arachidonic acid cascade since it was not influenced by indomethacin.

Action Potentials↗
PubMed1989

Plasma factors influencing PGI2-like activity in patients with IgA nephropathy and Henoch-Schönlein purpura.

Plasma factors influencing vascular PGI2-like activity (PSA) were studied in 45 patients with IgA nephropathy, 18 with Henoch-Schönlein purpura, including 8 children with nephrotic syndrome, and 41 controls. The results were compared with the levels of plasma high-density lipoprotein (HDL), low-density lipoprotein (LDL) and fatty acid components of plasma phospholipids. The plasma of 38 of 45 patients with IgA nephropathy and 14 with Henoch-Schönlein purpura showed a diminished ability or no ability to support PSA. Twenty-three patients with IgA nephropathy and 10 with Henoch-Schönlein purpura exhibited an inhibitory activity against PGI2 production. The plasma HDL level was lower, while the LDL level and the LDL/HDL ratio were significantly higher in IgA nephropathy and Henoch-Schönlein purpura cases than in the controls. A high LDL/HDL ratio was associated with a low plasma PSA. The levels of arachidonic acid and its precursor were not lower in the plasma of patients than in the controls. The decreased PGI2 synthesis may play an important role in the pathogenesis of IgA nephropathy and Henoch-Schönlein purpura, but it can not be explained by reduced PG precursors. LDL may have an inhibitory, and HDL a protective effect on PGI2 synthesis.

Adult↗
PubMed1988

Electrophysiological effects of GYKI-23 107, a new antiarrhythmic compound, in isolated rabbit and canine cardiac preparations.

The cellular cardiac electrophysiological effects of GYKI-23 107 (1-/2,6-dimethylamino/-2-dimethylaminopropane dihydrochloride), a new investigational antiarrhythmic drug, were studied in rabbit and canine ventricular muscle and Purkinje fibers. For comparison, mexiletine was used. GYKI-23 107, like mexiletine, did not affect the resting membrane potential and slightly reduced the action potential amplitude in both fiber types. The time for repolarization was shortened, but the ratio of effective refractory period to action potential duration was increased by both drugs. The maximum rate of depolarization (Vmax) was depressed by the drugs in a frequency-dependent ("use-dependent") manner. GYKI-23 107 slowed the recovery kinetics of Vmax in the canine ventricular muscle (Tc = 229.9 +/- 5.6 ms; n = 7) and Purkinje fiber (Tc = 149.6 +/- 33.8 ms; n = 7) in the same way as mexiletine. The kinetics of restitution of action potential duration during premature and postmature stimulation were slowed to similar degrees in the presence of both GYKI-23 107 and mexiletine in canine Purkinje fibers. It is concluded that, on the basis of its cardiac cellular electrophysiological effects, GYKI-23 107 can be categorized as a class Ib antiarrhythmic agent.

Animals↗
PubMed1988

On the nature and molecular basis of prostacyclin induced late cardiac changes.

The late appearing and long-lasting cardiac effects induced by PgI2 or its stable analogue 7-oxo-PgI2 described by us first in 1983 include: 1.) antiischemic, 2.) antiarrhythmic, 3.) selective electrophysiological and 4.) cardiac cytoprotective changes. Evidence for 1.: Protection from myocardial ischemia due to coronary occlusion in dogs furthermore a significant diminution of ischemic loss of the myocardial ATP and CP content and of the myocardial lactate accumulation in excised rat heart exposed to global ischemia. 2: Protection from postocclusion and reperfusion arrhythmias in dogs. 3: A selective prolongation of the ventricular refractory period (VERP) as well as of the action potential duration (APD90) in the isolated rabbit papillary muscle furthermore prolongation of QT distance and VERP in the rabbit and the guinea pig heart "in situ". 4.: The cardiac cytoprotective effect, i.e. ischemic loss of intracellular K+ and ischemic gain of intracellular Na+ in isolated hearts of 7-oxo-PgI2 treated guinea pigs subjected to 25 min global ischemia was significantly moderated. These protective actions proved to be dose and time dependent - maximal effects appeared 48 hrs after administration of a single dose of 50 micrograms/kg i.m. 7-oxo-PgI2. These effects are certainly not due to 7-oxo-PgI2 itself but this latter seems to be indispensable for induction of a long acting principle, which can probably be extracted from hearts of pretreated animals and this substance of lipoid character exerts electrophysiological effects similar to those observed after 7-oxo-PgI2 pretreatment. Pretreatment may also reduce isoproterenol induced heart rate increase and prolong bleeding time in conscious rabbits.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed1987

Surgical treatment of renovascular hypertension.

Unilateral stenosis of the renal artery was verified by angiography in 34 patients with hypertension. The cause-effect relationship between elevated blood pressure and stenosis of the renal artery was proved by detailed renin studies (basic plasma renin activity, plasma renin activity following orthostatic and diuretic stimulation, renal vein renin activity). Surgical treatment was applied in 39 cases: they were aortorenal bypass in 9, autotransplantation in 7, patch graft in 2, denervation in 2, decompression in 3 and nephrectomy in 16 cases. Six months following the operation, 68.4% of the patients were normotensive without drugs and 18.4% of them with a reduced dose of drugs. To achieve normotension preoperative treatment had to be continued only in 13.2% of the patients. Two to four years postoperatively, 29 patients were subjected to control examinations and in 23 cases also to angiography. Restenosis was observed in 4 patients (17.4%). As a result of surgical treatment, the increased response to hyperreninaemia and to various stimuli decreased. Based on the control examinations, 58.7% of the patients could be considered to be cured.

Adolescent↗
PubMed1986

Changes of serum lipids and lipoproteins during haemodialysis treatment in dialysed chronic uraemic patients.

Changes of serum lipids and lipoproteins were determined quantitatively before and after haemodialysis in chronic uraemic patients. Serum beta-lipoprotein significantly decreased due to haemodialysis, while alpha-lipoprotein and the FFA level significantly increased. Slight correlations were observed between the applied transmembrane pressure and the serum concentration of FFA, HDL-cholesterol or total cholesterol levels. Hyper-beta-lipoproteinemia was found in 70.9 per cent and Frederickson-HLP in 33.3% of the haemodialyzed chronic uraemic patients.

Adult↗
PubMed1984

Effects of hypoxia on the guinea-pig myocardium following inhibition of adenosine deaminase by coformycin.

The effect of moderate and severe hypoxia on the electrical and mechanical activity of isolated left atria of guinea-pigs was compared in the presence and absence of coformycin, a highly specific and tight-binding inhibitor of adenosine deaminase. The myocardial actions of hypoxia (reduction in the duration of intracellularly recorded action potentials and decrease in isometric tension, maximum velocity of contraction and relaxation as well as in time to peak tension) were significantly enhanced by coformycin, when applied in a concentration of 7 mumol/l producing nearly complete inhibition of adenosine deaminase in atrial muscle. These effects of coformycin were moderate during early hypoxia (0-5 min) and became pronounced during the late phase of oxygen deprivation (5-16 min). The results are in favour of the previous assumption that under hypoxic conditions the increased tissue level of adenosine might contribute to the functional impairment of the guinea-pig myocardium.

Action Potentials↗