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Biomedical subjects

I Nyáry

Publications and source records attributed to I Nyáry.

At least 19 recordsLinked to original sources
PubMed1997

[First Hungarian experiences with positron emission tomography (PET) studies. Members of the PET working group].

Diagnostic investigations commenced on the 28th of June 1994 in Hungary's and Central Europe's first PET Centre at the University Medical School of Debrecen. The Centre is equipped with a GE 4096 Plus whole body PET scanner. A metabolic tracer, 18F-deoxy-D-glucose (FDG), was used in the investigations. During the first 15 months 249 PET investigations were made in the Centre of which 242 were diagnostic and 7 normal subjects served as control for the patient studies with brain scans. The number of oncological indications (intra- and extracranial tumours, Hodgkin's lymphomas) was n = 105 (43.4% of the 242 diagnostic examinations), neurological investigations (without intracranial tumours) formed the dominant group (n = 117; 48.3%), whereas the number of cardiological indications was 20 (8.3%). The oncological studies included those of intracranial tumours (n = 76; 31.4%); thyroid tumours (n = 9; 3.7%); Hodgkin's lymphomas (n = 7; 2.9%) and other extracranial tumours (n = 13; 5.4%). The distribution of different neurological and psychiatric investigations was as follows: localization of focal epileptogen zone (n = 60; 24.8%); differential diagnosis of dementias (n = 30; 12.4%); exploration of cerebrovascular diseases (n = 10; 4.1%); and other neurological diseases (n = 17; 7.0%). The main objective of the cardiological PET investigations was the exploration of viable myocardium. The present paper overviews both the procedures (including administrative issues, as well) and the results of the first 249 FDG-PET investigations.

Aged↗
PubMed1996

Tumors of the cerebellopontine angle. Changing policy in treatment.

One hundred and twenty-six cases of cerebellopontine angle tumors with various histologies are presented. Results of 75 operated vestibular neurinomas, 22 meningiomas, and 16 tumors with other histologies are discussed. The method of irradiation and non-radical surgery may be an alternative for treatment.

Anastomosis, Surgical↗
PubMed1996

Endogenous opioid mechanisms in hypothalamic blood flow autoregulation during haemorrhagic hypotension and angiotensin-induced acute hypertension in cats.

The influence of naloxone-induced general opiate receptor blockade on hypothalamic blood flow autoregulation was investigated in anaesthetized, artificially ventilated, temperature controlled cats. In order to study the changes of the hypothalamic blood flow (H2-gas clearance technique) at the lower limit of autoregulation systemic arterial pressure was reduced in a stepwise manner to 100, 80, 60 and 40 mmHg, by haemorrhage. Autoregulatory mechanisms of the hypothalamic vessels remained effective and hypothalamic blood flow showed no significant reduction until the arterial pressure was reduced to 60 mmHg in the vehicle-treated control cats. General opiate receptor blockade by 1 mg kg-1 mL-1 i.v. injected naloxone resulted in a significant reduction of the autoregulatory capacity of the hypothalamic vessels: the blood flow followed passively the arterial pressure fall already from 100 mmHg mean arterial pressure. The effect of opiate receptor blockade on the upper limit of the autoregulation was studied during acute arterial hypertension, induced by angiotensin-II infusion (25 micrograms 0.1 mL-1 min-1 i.v.). Hypothalamic blood flow remained remarkably steady following angiotensin-II infusion in the saline-treated control animals. Naloxone pretreatment (1 mg kg-1 mL-1 i.v.), however, induced a significant downward shift of the upper limit of the autoregulation, and hypothalamic blood flow started to increase in the 125-145 mmHg arterial pressure range. The narrowing of the autoregulatory range following general opiate receptor blockade suggests an important role of endogenous opioid peptides in hypothalamic blood flow autoregulatory mechanisms both in hypotensive and in hypertensive conditions.

Angiotensin II↗
PubMed1996

Regional heterogeneity and differential vulnerability of cerebral and spinal vascular CO2-responsiveness during graded haemorrhagic hypotension.

Regional inhomogeneity of cerebrovascular CO2-sensitivity as well as its changes at three different levels of standardized haemorrhagic hypotension were studied in ten distinct brain and spinal cord regions of anesthetized, ventilated cats. Regional cerebral blood flow was measured with radiolabelled microspheres in hypocapnic, normocapnic, and hypercapnic conditions, and CO2-responsiveness was determined from the equation of the slopes of the best fit regression lines to the obtained flow values. It was concluded that in normotensive, normoxic cats response of the cerebral and spinal vessels to PaCO2 alterations can be assigned to four major categories. The CO2-responsiveness of a brain region is not solely determined by the rate of its basal steady state blood flow: CO2-reactivity of the hypothalamus was significantly different from that of any other investigated regions with almost identical steady state flow values. Vulnerability of the cerebrovascular CO2-sensitivity during hypotension was different from region to region, with the vessels of the pons-medulla oblongata region being the most sensitive to haemorrhage. Reduced regional cerebral and spinal CO2-responsiveness during haemorrhage is not a consequence of a reduced L-arginine supply for nitric oxide generation since administration of an excess amount of the precursor L-arginine failed to restore the haemorrhage-induced reduction of regional CO2-sensitivity at the 60 mm Hg mean arterial pressure level.

Animals↗
PubMed1990

Stroke rehabilitation: a method and evaluation.

Subjects of this study were 53 patients who presented with cerebrovascular stroke and who took part in a rehabilitation programme that included the basic elements of Bobath's concept and Peto's Conductive Education. The protocol called for a three point assessment: on admission to the rehabilitation ward and at one month and one year after entry. Baseline and follow-up examinations included clinical and laboratory tests, CT scan, cerebral blood flow studies and angiography. Motor functions were evaluated by the Rivermead Motor Assessment and dependence (ADL) was measured by the Barthel index. Neuropsychological evaluations were also made using Benton's test, Bourdon's letter cancellation test and the Wechsler Adult Intelligence Scale. Significant improvement was found in functional conditions both one month and one year after entry. There was a strong correlation between the Rivermead Motor Assessment and the Barthel index. The Rivermead Motor Assessment proved to be the most sensitive indicator of improvement in relation to the size and site of the infarct.

Activities of Daily Living↗
PubMed1988

Contralateral approach to bilateral and ophthalmic aneurysms.

In a previous survey, we found a high incidence of fatal rupture of an unclipped aneurysm in patients with multiple aneurysms. To deal with this problem, we introduced a more vigorous technique that accesses aneurysms previously considered unapproachable during one operating session. Attempts were made to clip middle cerebral and ophthalmic aneurysms contralateral to the operative exposure. We have successfully clipped contralateral aneurysms of the posterior communicating artery when bilateral aneurysms were present. We have also used this contralateral approach successfully with single ophthalmic and proximal carotid aneurysms that pointed medially. We review the cases of 39 patients with 43 intracranial aneurysms operated from the contralateral side and present the surgical technique in relation to the angiographic findings.

Adult↗
PubMed1984

Late reopening of an interposed vein graft for EC/IC bypass.

The authors report a case of EC/IC bypass with venous interposition between the external carotid artery and the middle cerebral artery cortical branch without function in the first eight months after surgery but, after the reopening of the graft, very good revascularization of the brain could be seen. The possible causes are discussed.

Brain Ischemia↗
PubMed1982

Dependency on bypass circulation: a case study.

In a case of consecutive occlusion of both internal carotid arteries bilateral STA-MCA anastomoses were established. Since a series of angiographic examinations were undertaken, dynamics and probable efficacy of both natural and artificial collateral circulations could be followed up in a two-year period. Objectively in the evaluation of anastomoses was enhanced by direct percutaneous STA-angiography (STAG), in order to delineate the vascular territory irrigated exclusively by the anastomosis. By demonstrating exactly the functional capacity of anastomoses in correlation with the clinical course, dependency on bypass circulation could be assessed.

Arterial Occlusive Diseases↗
PubMed1977

Local blood flow of the hypothalamus in haemorrhagic hypotension.

Local blood flow of the hypothalamus (HBF) was measured by the hydrogen clearance method in anaesthetized dogs. The average value for HBF in normal controls was 0.64 +/- 0.05 ml/g/min, which compares favourably with values available in the literature. During haemorrhagic hypotension induced by a modified Wiggers method there occurred a marked reduction of HBF to 52% of the initial control value at a mean arterial blood pressure (MABP) of 55--60 mm Hg and to 44% at 35--40 mm Hg. Prevention of concomitant extracellular acidosis by infusion of sodium bicarbonate solution during the hypotensive period resulted in a significantly smaller decrease in HBF as compared to an untreated control group, and a significant protection of HBF was also found at 55--60 mm Hg MABP in the bicarbonate treated group, but not in controls treated with physiologic saline. Hypothalamic tissue hypoxia was inevitable in untreated bled animals due to insufficient circulatory transport, while evidence suggested that the metabolism might have remained unaltered in the group protected against acidosis during haemorrhage. Analysis of the control of local hypothalamic blood flow revealed a significant correlation (r = 0.7026, p less than 0.001) between HBF and arterial blood pH in severe hypotension which is outside the autoregulatory blood pressure domain.

Acidosis↗
PubMed1976

Analysis of reflex changes in hepatic tissue blood flow elicited from the intestinal mucosa.

The reflex changes of local hepatic blood flow (HBF) were studied in anaesthetized dogs. An increase of HBF following the acidification of duodenal mucosa and the injection of glucose solution into the intestinal lumen was demonstrated. An attempt was made to cast light on the underlying mechanism which may govern the above mentioned local circulatory reflexes in the liver, by investigating the effect of bilateral vagotomy and of the local anaesthesia of duodenal mucosa. The importance of these hepatic circulatory reflexes from the point of view of surgical indications and the clinical treatment is discussed.

Anesthesia, Local↗