PubMed Health⌕ Search

Biomedical subjects

L A Debreczeni

Publications and source records attributed to L A Debreczeni.

At least 37 records · Page 2Linked to original sources
PubMed1987

Spectral analysis of cough sounds recorded with and without a nose clip.

The voluntary cough sounds of healthy volunteers, patients with chronic rhinitis, chronic rhinitis with bronchial asthma and asthma were recorded with and without a nose clip. A gated series of signals of the first cough sound lasting 200 ms was analysed by a system with a 20 ms delay of the first signal. In the case of filtered cough sounds, low-cut digitally, the mean values of averaged spectra of the healthy volunteers showed a first peak around 350 Hz, similar to the expiratory spectra of respiratory sounds. Second and third harmonics were also identified. The mean values of averaged spectra from the patients with airway disease differed significantly in the range of low frequency components. The upper airways work as narrow-band acoustic filters determining the harmonic contents of speech as well as those of cough sounds. To minimize these effects for acoustic analytical purposes, the application of a nose clip is suggested to find the cough harmonics related to those of pulmonary sounds. The voluntary cough sounds contain diagnostic information, but to build up a quantitative, diagnostic, decision-making system, further investigations as well as standardization of recording and analysis are necessary.

Adolescent↗
PubMed1985

Species dependent relaxation of intrapulmonary arteries (IPA) of rabbits, dogs and humans by prostacyclin.

Helically cut strips of successive IPA segments of rabbits, dogs and human patients were set up for isometric recording in vitro. High tone was produced by norepinephrine (NE, 3 microM). This tone was markedly reduced by prostacyclin (PGI2) in the secondary, tertiary and quaternary branches of human and canine pulmonary trunk. The IC50 values for PGI2 ranged from 22 to 503 nM, the human vessels being more sensitive to prostacyclin than canine IPA. Under these conditions, the primary and secondary branches of the rabbit pulmonary trunk were not relaxed by PGI2. The contractile potency of NE was determined in each pulmonary vessel studied. The secondary segments of rabbit IPA were about ten times as sensitive to NE (EC50 for NE: 38 +/- 7 nM) as compared to the secondary IPA from dogs and humans (EC50 values: 370 +/- 84 and 440 +/- 50, respectively). When high tone was induced by equieffective contractile concentrations of NE (3 microM for canine and human IPA and 0.3 microM for rabbit vessels), PGI2 was still less effective (P less than 0.01) in relaxing secondary IPA of rabbits (IC25: 220 +/- 55) than the corresponding segments of dogs and humans (IC25: 51 +/- 12 and 17 +/- 4, respectively). The difference between canine and human vessels was also significant (P less than 0.02). These results indicate that there is an interspecies difference in the sensitivity of IPA to NE and PGI2.

Animals↗
PubMed1981

Effect of carotid sinus reflex on the circulation of rats bearing Guérin carcinoma.

The effect of carotid occlusion was studied on cardiac output (Evans blue dilution) and its fractional distribution (Sapirstein's isotope fractionation technique) in rats with and without Guérin carcinoma. In response to the carotid sinus hypertensive reflex (CSHR), in normal rats blood pressure and TPR were augmented; vascular resistance of the kidneys, intestines, skin and carcass was increased. In tumour bearing rats CSHR resulted in comparable increments of vascular resistance in various organs. Tumour blood flow remained unchanged, whereas vascular resistance of the tumour was considerably increased.

Animals↗
PubMed1980

Effect of phenoxybenzamine, propranolol, phenylephrine and isoproterenol on the circulation of rats bearing Guérin carcinoma.

Effects of phenoxybenzamine (1 mg per 100 g i.v.), propranolol (0.2 mg per 100 g i.v.), phenylephrine (0.1--0.3--1.0--3.0 micrograms per 100 g per min) and isoproterenol (0.01--0.03--0.1--0.3 micrograms per 100 g per min) were studied on cardiac output (Evans-blue dilution), organ and tumour blood flows (Sapirstein's isotope indicator dilution technique) in rats bearing Guérin carcinoma. In agreement with our earlier results data for haematocrit, blood pressure, TPR and organ vascular resistance were lower whereas cardiac index and organ blood flow were higher in control untreated tumour-bearing animals than in untreated normal rats. Phenoxybenzamine, depending on tumour size, decreased blood pressure, TPR and vascular resistance of organs, while it was found ineffective in rats with tumours of very large size (60--80 g). Propranolol treatment produced slight and similar effects in both normal and tumour-bearing rats. Phenylephrine enhanced peripheral resistance as a function of log dose in both normal and tumour bearing animals, nevertheless in the latter group it elicited more marked responses in the vascular bed of the kidneys, intestines and skin. The vasodilatory log dose dependent effect of isoproterenol was not present in tumour-bearing rats. In addition to the anaemia, the continuous decrease of alpha adrenergic activity in the systemic circulation parallel with tumour growth appears to be the most reasonable explanation for the "hyperkinesis" observed in tumour-bearing rats. Resistance of tumour vascular bed was increased by both phenoxybenzamine and propranolol. During the course of phenylephrine infusion (1.0 or 3.0 micrograms per min) the resistance of tumour vessels was more increased than that of other organs. Isoproterenol infusion resulted in a vasoconstriction of the tumour vessel. It appears that with maximally dilated vessels, vasoconstriction remains the only possible vascular response in Guérin carcinoma. In the vascular bed of the tumour a preponderance of beta adrenergic receptors also seems to be feasible.

Animals↗
PubMed1979

Regional vascular reactivity in rats with Guérin carcinoma (GC).

Increased sensitivity to phenylephrin and a decreased one to isoproterenol has been found in regional vascular beds of GC implanted rats. Circulatory sympathetic reflex adaptation, alfa- and beta-adrenergic stimulation or blockade provoked a uniform response pattern: i.e. increase in vascular resistance of GC.

Animals↗
PubMed1979

Effect of haemorrhagic hypotension on the circulation of rats with Guérin carcinoma.

After transplanting Guérin carcinoma in rats the cardiac output (Evans-blue dilution), the distribution of cardiac output (Sapirstein's isotope indicator fractionation technique), the nutritive blood flow of the organs, and their circulatory resistance were investigated in haemorrhagic hypotension (40 or 70 mm Hg). The posthaemorrhagic redistribution of cardiac output in tumor-bearing rats was similar to that found in normal bled animals: the renal and skin fractions of cardiac output decreased and that of the brain, myocardium, and carcass increased. As a result of bleeding the decrease of the tumor fraction of cardiac output was the greatest compared to the other organs. Thus the tumor seems to be the main target organ of the posthaemorrhagic redistribution.

Animals↗
PubMed1978

Effect of external compression on the postocclusion hyperaemic response of the coronary arteries in the isolated fibrillating dog heart.

The effect of external compression on the postocclusion hyperaemic responses (occlusion time 15, 30, 60 sec) has been studied on the fibrillating canine heart. The heart was placed in a closed organ box containing physiological saline solution, and the coronaries were perfused with blood from a donor dog using a constant volume perfusion technique at 150 mmHg perfusion pressure. The pressure in the organ box varied between 0--50 mmHg. As the compression pressure increased in the organ box, coronary blood flow, basal conductance as well as the parameters of the postocclusion hyperaemic reaction (peak conductance, reactivity, mean transit time of hyperaemia, postocclusive conductance area, and repaymen) decreased. The factors (tissue diffusion, tissue pressure, transmural pressure) at the capillary level can influence the regulation of the postocclusion vasodilatation and the results cannot be explained by metabolic and/or myogenic processes alone.

Animals↗
PubMed1975

Circulation in rats with Guérin carcinoma.

After implantation of Guérin carcinoma in rats, cardiac output (by Evans-blue dilution), distribution of the organ fractions of cardiac output (by Sapirsteins's isotope indicator fractionation technique), nutritive blood flow and circulatory resistance of the organs (including the tumor) were studied. The following parameters were altered proportionately to the weight of the tumor (0.39-84.0 g): a) weight of gut and carcass diminished; b) cardiac index increased, blood pressure and total peripheral resistance decreased; c) tumor fraction of cardiac output was augmented; d) blood flow of the organs increased and their circulatory resistance decreased. Hematocrit decreased from 47.2 to 31.0% 20 days after tumor implantation. In rats with tumor the changes of blood flow may be conditioned by both anemia and the decrease in organ weight.

Animals↗
PubMed1975

Interaction of heart glycosides and phenobarbital.

One week's administration of phenobarbital does not affect the disappearance of a single dose of digitalis glycosides from the serum of man. The increase of bile flow and of liver weight produced by phenobarbital in the rat is not further enhanced by glycosides. In case of acute digitalization, the enzyme inducing effect of barbiturates has probably no clinical significance.

Adolescent↗
PubMed1975

Circulatory regulation in anuric rats: anuria and haemorrhagic hypotension.

In rats made anuric by ureteral ligation or by creating a bladder-caval venous shunt, cardiac index increased and total peripheral resistance decreased proportionally to the change in the serum NPN level. Circulating blood and plasma volume did not change. In ureteral-ligated or bladder-caval venous-shunted rats, cardiac output and its organ fractions were determined by SAPIRSTEIN'S technique. In the ureteral-ligated animals, vasoconstriction in the kidneys, and vasodilation in the skin were found. After bladder-caval shunt, vasodilatation developed in the myocardium, gut, skin and carcass. After ureteral ligation, posthaemorrhagic shifting decreased mainly the renal flow, while after a bladder-caval venous shunt, mainly the renal and intestinal flows.

Animals↗