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Biomedical subjects

L Papp

Publications and source records attributed to L Papp.

At least 73 records · Page 4Linked to original sources
PubMed1986

[Experiences with thermography in the surgical treatment of ischemic heart disease].

Possible use of thermography (AGA Thermovision 750) in heart surgery has been investigated in animal experiments and in human extracorporeal operations as well. In six open-chest isolated dog hearts, coronary circulation had been occluded and antero- and retrograde local cooling was employed. Following coronary occlusion, effective hypothermia was achieved retrograde via the coronary sinus. 22 patients were arranged into three groups according to the operation technique used, and the possibilities for effective cardiac cooling by cold cardioplegic solution were studied. Hearts of the six patients subjected to surgical intervention for valvular lesions (four mitral and two aortic) could be safely cooled by cold cardioplegic solution infused through the aorta or the coronary arteries. The hearts of the twelve patients with coronary artery stenosis could be cooled sufficiently by additional retrograde infusion only. Employing antero- and retrograde hypothermia, in four patients the size of the aneurysm of the left ventricle, and the area which had to be resected was determined by thermography. Thermography is considered to be a suitable non-invasive method to derive information concerning: the efficacy of cold cardioplegic solution in aortocoronary bypass grafting, quantitative changes in nutritive coronary flow, the size of left ventricular aneurysmectomy.

Adult↗
PubMed1986

Haemodynamic and thermographic signs of intramyocardial venous outflow redistribution induced by coronary sinus occlusion in the canine heart.

Short occlusions of the coronary sinus (CS) were performed in open chest dogs in order to study the clinico-physiologic aspects of changes induced by this manoeuvre both in intracoronary pressure distribution and myocardial blood supply. It was found that when mean CS blood flow (EM flowmeter) was plotted against mean CS pressure during the gradual blockade of the CS outflow, a perfectly linear relation could be established between these variables beyond the physiologic CS pressure range (greater than 10 mmHg). Inotropic stimulation (adrenaline administration), without affecting its basic characteristics, shifted this line to higher pressure-flow ranges. On occluding the sinus, intracoronary arterial pressure distal to the ligated LAD branch also increases, but to a lesser degree than CS outflow pressure; within the ischaemic zone this results in a complete reversal of the arteriovenous pressure gradient during a considerable part of the cardiac cycle. Blood supply to the non-ischaemic heart was estimated with the aid of the computerized thermographic method developed by the authors. It was demonstrated that cardiac heat emission reflecting changes in subepicardial blood flow is singularly little affected by CS occlusion. From all these findings it is evident that occlusion of the CS involves a drastic coronary outflow redistribution but not a drastic inflow reduction in the heart. The results were interpreted in terms of newly developed cardiosurgical procedures aimed at to preserve myocardial viability, and it was concluded that the occurrence of adverse coronary actions offsetting the potential benefits of these procedures is of very low probability.

Animals↗
PubMed1986

Inosine increases anoxic tolerance and postischaemic restitution of the heart: experimental studies on possible mechanism(s) of action.

Various experimental models were utilized to determine the in vivo cardiac actions underlying the presumptive therapeutic benefit of the naturally occurring adenine nucleoside, inosine. 1. In pentobarbital-anaesthetized dogs coronary vasodilator responses to arterial hypoxia were augmented and postanoxic depression of cardiac contractile force was prevented by i.v. infusion of inosine (5 mg X kg-1 X min-1). 2. Thermographic observations demonstrated in the in situ dog heart a significant inosine-induced epicardial warming (coronary flow increase) which was resistant to P1-purinergic blockade (aminophylline). 3. Following total cardiopulmonary bypass and cardioplegic cardiac arrest of 90 min duration in the dog, inosine administration (5 mg X kg-1 X min-1) evoked a lasting increase in myocardial contractile force and cardiac output. 4. In Langendorff perfused guinea pig hearts subjected to normothermic ischaemia of 1 hour duration and treated with inosine (0.05 mg X min-1), the release of cytoplasmatic enzymes (CK-MB, alpha-HBDH) and myoglobin was significantly less than in untreated ischaemic controls. In the two latter series of experiments (3 and 4) the inosine action was contrasted by the deleterious effect of catecholamines (noradrenaline and isoproterenol) administered in moderate or small doses, respectively. It was concluded that inosine has cardioprotective actions partly related to and partly independent of its influence on coronary blood supply, suggesting that administration of the nucleoside may be useful in various surgical attempts directed to myocardial salvage.

Animals↗
PubMed1986

Thermographic study of haemodynamic changes due to arteriovenous shunt.

The authors made thermographic studies on the haemodynamic changes due to arteriovenous shunt in animal experiments under different conditions. The effects due to acute and chronic fistulas in reaction-free and inflammatory environments were registered. Observations of diagnostic value were made on the haemodynamic changes due to arteriovenous shunt. These are of differential diagnostic importance also in human medical practice, therefore thermography is recommended to be used as new noninvasive diagnostic tools.

Animals↗
PubMed1985

The role of taxonomy in the control of flies pestering grazing cattle and sheep in Hungary.

A reliable and stable taxonomic basis is necessary for improvements in the control of secretophagous and blood-sucking flies visiting pastured cattle because the number of these dipterous species is very high; the community differs from area to area; and a better knowledge of the biology of the species can aid the development of more effective control measures. The actual size and density of populations cannot be estimated accurately on the basis of individual flies caught from or counted on cattle or in their environs. The true densities can only be determined by rearing the flies. It would appear that no single control method can be effective against all species because of the major differences in biology between them. In this taxonomy can help. Thirty-one species of Diptera, several of veterinary importance, have been reared from sheep droppings. Sheep droppings have no autochthonous community and all species reared also occur in cattle droppings, although in different proportions.

Animals↗
PubMed1985

Natural history of acute regional myocardial ischaemia revealed by infrared thermography in the canine heart.

Acute ischaemia of the left ventricular apical region has been produced by occluding for 60 min the upper mid-portion of the left anterior descending (LAD) coronary artery in the exposed heart of anaesthetized dogs. The decrease of the blood supply to this region was associated with characteristic morphologic patterns of the subepicardial temperature distribution which has been visualized with the aid of telethermography using an AGA 750 thermovision equipment. The thermographic cardiac images recorded during the progressive development and the restitution of the ischaemic events were evaluated with a new computer-assisted method developed by the authors and the results were described in composite histograms. The validity of the assumption that subepicardial cooling and warming in a particular region could be ascribed to a decrease and increase, respectively, of local flow, was substantiated by computerized simulation of myocardial heat transfer. In both the intact and the ischaemic (collateral-dependent) portions of the heart the issues of the quantitative evaluation of experimental data were indicative of important dynamic factors that elicit, depending upon some partially known individual characteristics, either compensatory adjustments in the entire myocardium (generalized vasodilation) or a demarcation of the infarct (selective flow decrease). Proofs obtained in additional experiments by administering exogenous catecholamines suggest that ischaemically transformed adrenoceptor mechanisms may play a significant role in the latter process. It was concluded that the quantitative thermographic technique developed by the authors is suitable, due to its considerable temporal and spatial resolution, for concurrent analysis of the time course and the gross morphologic details of cardiac ischaemia in vivo.

Animals↗
PubMed1985

Computer-aided thermographic evaluation of disturbances of the coronary adaptive reserve: an experimental study.

Brief episodes of severe ischaemic loads have been reported to attenuate or abolish the vascular autoregulatory capacity, including reactive hyperaemic vasodilation, in the coronary bed. It is suggested that the developed loss of the coronary adaptive reserve and the consecutive ultrastructural alterations can be considered an experimental model for the human effort anginal attacks occurring without significant mechanical constriction of the vessels. The functional morphologic patterns in this state were analysed by the new quantitative technique which is based on the computerized evaluation of cardiac thermograms taken with a thermovision (AGA 750) equipment. In the isolated perfused heart of rabbits, the total adaptive loss developed in the overall flow (cessation of reactive hyperaemia) was found to be associated with slow reacting coronary vessels in the cardiac surface, a delayed shift of the computerized thermographic profiles to warmer ranges during reactive hyperaemia. The pattern strongly suggested a redistribution of flow from the subendocardium. In further observations, simulated emergency coronary bypass operations on dog hearts revealed another distinct thermographic pattern: a reduced vascular adaptive range without considerable delay in reactivity. The studies demonstrated the usefulness of quantitative thermography in visualising and differentiating the various types of coronary dysfunction.

Adaptation, Physiological↗
PubMed1984

Clinical and experimental study of cold cardioplegic myocardial protection.

The authors used a multi-dimensional approach to the study of the effects of intra-operative myocardial protection; the results of three series of investigations are reported. First, conditions underlying the effectiveness of the authors' modified cardioplegic solution were studied by laboratory and histological methods in ex vivo guinea pig hearts. Evidence is presented for the detrimental effects of catecholamines and the beneficial action of inosine. The second part of the report deals with problems of effective myocardial cooling in partially ischaemic canine hearts, investigated by infrared thermographic examinations of temporal and spatial thermal distribution over the entire visible cardiac surface. At last the authors present the result of their complex intra- and postoperative enzyme analysis combined with mathematical evaluation (cluster analysis in a group of patients suffering from ischaemic heart disease).

Animals↗
PubMed1983

Study of trace elements in patients on haemodialysis.

The serum aluminium, zinc, copper, iron and cadmium levels were studied in patients on haemodialysis, by the atomic absorption method and spectrophotometry. The serum concentrations of zinc and copper were found to decrease with the frequency of dialysis treatments, while the serum levels of iron and aluminium increased. Referred to the time elapsed since the start of the dialysis programme, the serum concentrations of zinc decreased, while those of iron, copper and aluminium increased. Attention is drawn to published observations pointing to the hazard of aluminium intoxication and to the symptoms and consequences of copper and zinc deficiency.

Adult↗