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Biomedical subjects

I Fekete

Publications and source records attributed to I Fekete.

At least 19 recordsLinked to original sources

Application of sequential extraction with supercritical CO(2), subcritical H(2)O, and an H(2)O/CO(2) mixture for estimation of environmentally mobile heavy metal fractions in sediments.

Results from use of a new isolation procedure based on sequential extraction with supercritical CO(2), subcritical H(2)O, and an H(2)O/CO(2) mixture in the same supercritical fluid extractor have been compared with results from the BCR-recommended three-step sequential extraction procedure. The new procedure gives more detailed information about environmentally mobile fractions (water-soluble, bicarbonate-forming), and in less time (5-6 h), than the BCR procedure.

Carbon Dioxide↗

The Mureş-Uzhgorod-Debrecen study: a comparison of hospital stroke services in Central-Eastern Europe.

Stroke mortality is extremely high in Central-Eastern European countries. The high rate of risk factors and differences in health care services might be among the factors resulting in high stroke morbidity and mortality in this region. As only few prospectively collected information are available from this region, we decided to evaluate some characteristics of stroke services in neurological departments of a Romanian, a Ukrainian and a Hungarian city in the framework of the Mureş-Uzhgorod-Debrecen comparative epidemiological study. We registered demographic data, the absence or presence of the most important risk factors, and clinical signs on admission and at discharge. We recorded the application of various diagnostic methods, stroke treatment and recommendations for secondary prevention. Follow-up is planned after 30 days and after 1 year. The paper summarizes the methodology of this prospective epidemiological study of stroke patients hospitalized in neurological departments in Târgu Mureş, Uzhgorod and Debrecen, three Central-Eastern European cities in Romania, Ukraine and Hungary, respectively.

Follow-Up Studies↗

[The effect of a single-dose intravenous vinpocetine on brain metabolism in patients with ischemic stroke].

The effect of a single-dose i.v. infusion of vinpocetine on the cerebral blood flow (CBF) and glucose metabolism of post-stroke patients was studied by measuring the regional and global cerebral metabolic rates of glucose (CMRglu) and the corresponding kinetic constants before and after treatment. Transcranial Doppler (TCD) and single photon emission tomography (SPECT) measurements were also performed. The cerebral glucose metabolism was significantly higher in the contralateral hemisphere than in the affected one before therapy. In the affected hemisphere the regional glucose metabolism was inhomogenous: relatively low values were measured in the stroke region, whereas it was increased in the peristroke region. Although a single-dose vinpocetine treatment did not affect significantly the regional or global metabolic rates of glucose, the glucose transport (both intracellular up-take and release) was strongly affected in the whole brain, in the contralateral hemisphere and in the peri-infarct area of the symptomatic hemisphere. A slightly increased (not significant, N. S.) cerebral blood flow could be observed in the contralateral and a decreased flow (N. S.) in the symptomatic hemisphere.

Aged↗

Mannitol for acute stroke.

BACKGROUND: Mannitol is an osmotic agent and a free radical scavenger so it might decrease oedema and tissue damage in stroke. OBJECTIVES: To test whether treatment with mannitol reduces short and long-term case fatality and dependency after acute ischaemic stroke or cerebral parenchymal haemorrhage. SEARCH STRATEGY: We searched the Cochrane Stroke Group Specialised Trials Register. In addition to this, supplementary MEDLINE searches were performed. The Chinese Stroke Trials Register was checked and the Latin-American databank LILACS was searched with the search term MANNITOL and its variations in the Portuguese and Spanish languages. A search was performed of Masters and Ph.D. degree theses in the databank of Sao Paulo University, and in abstracts of medical congresses on neurology and neurosurgery from 1965 to 1997 in Brazil. SELECTION CRITERIA: Truly randomised unconfounded clinical trials comparing the effect of mannitol with placebo or open control in patients with acute ischaemic stroke or parenchymal haemorrhage were eligible for inclusion. DATA COLLECTION AND ANALYSIS: Two reviewers independently selected the trials to be included in the review. After reaching an agreement on which trials to include, two of the reviewers extracted data from the trials and performed the data analysis. Accuracy of data extraction was checked by comparing the results. Included trials were tabulated for methodological quality including the method of randomisation and blinding, and stating if CT was performed, if patients were lost to follow-up and if intention-to-treat analysis was performed. Data synthesis and analysis was performed using the Cochrane Review Manager software. MAIN RESULTS: Only one trial fulfilled the inclusion criteria. The number of included patients was small (36 treated and 41 controls) and the follow up was short. Neither beneficial nor harmful effects of mannitol could be proved. Case fatality, the proportion of dependent patients at the end of the follow up and side effects were not reported and were not available from the investigators. The planned outcome analyses and sensitivity analyses could not be performed due to lack of appropriate trials. REVIEWER'S CONCLUSIONS: There is currently not enough evidence to decide whether the routine use of mannitol in acute stroke would result in any beneficial or harmful effect. The routine use of mannitol in all patients with acute stroke is not supported by any evidence from randomised controlled clinical trials. Further trials are needed to confirm or refute the routine use of mannitol in acute stroke.

Acute Disease↗

Natural coagulation inhibitor proteins in young patients with cerebral ischemia.

Disturbances of coagulation and fibrinolytic pathways were studied in 53 young patients with cerebral ischemia. Upon admission 26 of 53 patients had abnormality in at least one of the antithrombin-III, protein C, protein S activities or in activated protein C (APC) ratios. Three months after the first examination the majority of the previously detected abnormalities returned to normal values and the most frequent alterations were decrease in protein S activity (3 patients) and APC resistance (3 patients). Conditions resulting in impaired fibrinolysis were frequently detected upon admission. Elevation of plasminogen activator inhibitor-1, lipoprotein (a), and alpha-2-antiplasmin was present in 23, 10, and 4 cases, respectively. It is concluded that abnormalities of coagulation as well as of the fibrinolytic systems are prevalent in the acute phase of cerebral ischemia, however, the results may be significantly influenced by the disease process or the acute phase effect.

Acute Disease↗

Hypoglycemia activates compensatory mechanism of glucose metabolism of brain.

The effect of plasma glucose concentration on the cerebral uptake of [18F]-fluorodeoxy-D-glucose (FDG) was studied in a broad concentration range in a rabbit brain model using dynamic FDG PET measurements. Hypoglycemic and hyperglycemic conditions were maintained by manipulating plasma glucose applying i.v. glucose or insulin load. FDG utilization (K) and cerebral glucose metabolic rate (CGMR) were evaluated in a plasma glucose concentration range between 0.5 mM and 26 mM from the kinetic constant k1, k2, k3 obtained by the Sokoloff model of FDG accumulation. A decreasing set of standard FDG uptake values found with increasing blood glucose concentration was explained by competition between the plasma glucose and the radiopharmacon FDG. A similar trend was observed for the forward kinetic constants k1, and k3 in the entire concentration range studied. The same decreasing tendency of k2 was of a smaller magnitude and was reverted at the lowest glucose concentrations where a pronounced decrease of this backward transport rate constant was detected. Our kinetic data indicate a modulation of the kinetics of carbohydrate metabolism by the blood glucose concentration and report on a special mechanism compensating for the low glucose supply under conditions of extremely low blood glucose level.

Animals↗

Vinpocetine for acute ischaemic stroke.

BACKGROUND: Vasoactive and neuroprotective drugs are used to treat stroke in some countries. OBJECTIVES: The objective of this review was to assess the effect of vinpocetine in acute ischaemic stroke. SEARCH STRATEGY: We searched the Cochrane Stroke Group trials register (last searched: August 1999) and Medline. We contacted researchers in the field and drug companies. SELECTION CRITERIA: Unconfounded randomised trials of vinpocetine compared with placebo, or any other reference treatment, in people with acute stroke. Trials were included if treatment started no later than 14 days after stroke onset. DATA COLLECTION AND ANALYSIS: Two reviewers independently applied the inclusion criteria. One reviewer extracted the data that was then checked by the second reviewer. Trial quality was assessed. MAIN RESULTS: One trial involving 40 patients was included. Data for 33 patients were reported. No deaths occurred in the trial and no significant difference in dependency was shown between the treatment and placebo groups. No adverse effects were reported. REVIEWER'S CONCLUSIONS: There is not enough evidence to evaluate the effect of vinpocetine on survival or dependency of patients with acute stroke.

Brain Ischemia↗

Cochrane report: A systematic review of mannitol therapy for acute ischemic stroke and cerebral parenchymal hemorrhage.

BACKGROUND: Mannitol was reported to decrease cerebral edema associated with tissue damage and is used to treat acute stroke in many countries. SUMMARY OF REVIEW: We tested whether there is any evidence from unconfounded randomized clinical trials that treatment with mannitol reduces short- and long-term case fatality and dependency if administered after ischemic stroke or cerebral parenchymal hemorrhage. Trials were identified by the standard search strategy of the Cochrane Collaboration Stroke Review Group. A supplementary MEDLINE search was performed, and the Chinese Stroke Trials Register and the Latin-American databank LILACS were checked. A search was performed of master's and PhD degree theses in the databank of Sao Paulo University and in abstracts of medical congresses on neurology and neurosurgery during 1965-1997 in Brazil. Investigators were contacted for unpublished information. Only truly randomized unconfounded clinical trials were eligible for inclusion. Two of the reviewers independently extracted data from the trials. Data synthesis and analysis was performed with the use of the Cochrane Review Manager software (RevMan version 4.0.4). CONCLUSIONS: Only 1 trial fulfilled the inclusion criteria. The number of included patients was small, and the follow-up was short. Case fatality, the proportion of dependent patients, and side effects were not reported and were not available from the investigators. As a result of lack of appropriate randomized trials, currently no conclusion can be drawn on the effects of mannitol in acute stroke. The routine use of mannitol in all patients with acute stroke is not supported by evidence from randomized controlled clinical trials.

Acute Disease↗

[Carotid atherosclerotic lesions in stroke patients with diabetes mellitus].

The aim of the study was to assess the incidence of atherosclerotic lesions on carotid arteries among diabetic subjects suffering from cerebrovascular accident. A further aim was to investigate the relationship between the severity of the carotid lesion, the stroke subtype and the fatal outcome. One hundred and sixty eight patients treated because of cerebrovascular accident at the Dept. of Neurology University Medical School of Debrecen were studied. The age of the patients, the duration of diabetes and hypertension were registrated. Base on duplex scanning carotid lesions were divided in 6 groups of severity (normal, intimal sclerosis, slight, moderately severe, severe stenosis and occlusion). Based on clinical signs and CT results stroke subtypes were divided into five groups (lacunar and non-lacunar infarctions, hemorrhages, normal CT and others). The relationship between severity of carotid lesions, stroke subtype and lethal outcome was assessed using statistical tests. Carotid stenosis of different severity was detected in 60% of the cases. Severity of stenosis was independent from duration of diabetes, but it was positively related to duration of hypertension (p = 0.016). In 1/3 of the patients lacunar strokes, in another 1/3 non-lacunar strokes were observed. No significant relationship was found between severity of carotid stenosis, stroke subtype and lethal outcome of the patients (p = 0.53 and p = 0.26 respectively). Diabetic patients suffering from stroke have a higher incidence of carotid artery atherosclerotic lesions than diabetics without stroke. A special attention should be paid to the carotid duplex sonography in order to detect diabetic cerebral macroangiopathies in early, asymptomatic stage.

Aged↗

A systematic review of vinpocetine therapy in acute ischaemic stroke.

OBJECTIVES: To determine whether vinpocetine decreases short- and long-term case fatality and proportion of dependent survivors if administered within 2 weeks of stroke onset. METHODS: All published and unpublished trials were attempted to be identified using the standard search strategy of the Cochrane Collaboration Stroke Review Group, using MEDLINE searches performed with all known manufacturer code names and trade names of vinpocetine and by contacting manufacturers of vinpocetine to give information of all randomised controlled trials on vinpocetine in stroke. Researchers who participated in trials on vinpocetine in Hungary were asked for further information. Only truly randomised, unconfounded clinical trials that compared the effect of vinpocetine to either placebo or another reference treatment for acute stroke where treatment started no later than 14 days after stroke onset were eligible for inclusion. Data synthesis and analysis was performed using the Cochrane Review Manager software (RevMan version 3.0). RESULTS: Among the identified studies on vinpocetine in stroke, only one fulfilled the selection criteria for inclusion in the review. No death occurred in the study groups and no statistically significant difference was found in dependency between the treatment and the placebo groups. No adverse effects were reported. CONCLUSIONS: Based on only one small randomised controlled unconfounded study, presently there is not enough evidence to decide whether the administration of vinpocetine does or does not decrease case fatality and dependency in acute stroke.

Cerebrovascular Disorders↗

Preparation and primary evaluation of [11C]CSC as a possible tracer for mapping adenosine A2A receptors by PET.

A 11C labeled selective adenosine A2A antagonist, (E)-8-(3-chlorostyryl)-1,3-dimethyl-7-[11C]methylxanthine [11C]CSC) was prepared by the reaction of (E)-8-(3-chlorostyryl)-1,3-dimethylxanthine and [11C]methyl iodide. The decay-corrected radiochemical yield was 32.3% with a radiochemical purity of 99%, a specific activity of 1.85-5.55 GBq/mumol and a preparation time of 1 h. A primary evaluation of [11C]CSC as a potential tracer for mapping adenosine A2A receptors by positron emission tomography (PET) is also presented. Biodistribution and autoradiographic studies were carried out on Swiss mice and domestic rabbits. In mice the lung showed the highest uptake at 10 min after i.v. injection, followed by the liver, kidney, heart and brain. Inside the brain a high level of radioactivity accumulated in the striatum, in accordance with previous findings on the specific spatial distribution of A2A adenosine receptors and also in the medulla oblongata. Dynamic PET studies on rabbits showed a fast brain uptake of CSC, reaching a maximum in less then 2 min. On the basis of competition experiments with the unlabeled ligand [11C]CSC proves to bind specifically to the appropriate receptor.

Animals↗

Basic characteristics of hospital stroke services in Eastern Hungary.

Stroke mortality is extremely high in Central-Eastern European countries. We report basic characteristics of a stroke unit in Eastern Hungary, including age and sex distribution; the proportion of transient ischemic attacks (TIA), ischemic and hemorrhagic strokes; case fatality; application of diagnostic methods; and length of stay for all patients treated with acute cerebrovascular disease over a 12-month period. Records of all patients with acute cerebrovascular disease (n = 522) discharged in 1995 from a stroke unit with a well defined catchment area of 220,000 inhabitants in Eastern Hungary were retrospectively analyzed. Case fatality was 18.6% for all patients and 21.1% after excluding cases with TIA. Computer tomography, duplex carotid ultrasound, cerebrospinal fluid examination and electroencephalography were performed in 79%, 77%, 7% and 2% of the patients, respectively. The database of the university hospital with the same catchment area was electronically searched for patients who were discharged with the diagnosis of stroke from the three departments of internal medicine. Stroke mortality data of the catchment area based on death certificates was obtained from the Central Statistical Bureau. Two hundred twenty-eight stroke deaths were reported in the catchment area in 1995. In the same period 97 stroke deaths occurred at the stroke unit and 76 at the departments of internal medicine. If we aim to treat all patients with acute stroke at the stroke unit, with the present stroke incidence and duration of hospital stay the current capacity of the stroke unit (1 bed per 10.000 inhabitants) should be doubled.

Adult↗

Screening of vascular cognitive impairment on a Hungarian cohort.

Cerebrovascular disease is a major public health problem in Eastern European countries. A Hungarian post-stroke population was examined to estimate the rate of dementia, the risk factors for cognitive impairment, and the applicability of a recently established Canadian diagnostic checklist in this cohort. Chronic cerebrovascular outpatients were screened for cognitive impairment with a combined checklist: the Diagnostic Checklist for Vascular Dementia established by the Consortium of Canadian Centres for Clinical Cognitive Research using the Mini Mental State Examination instead of the detailed neuropsychological part of the Checklist. Of the 247 consecutive patients at a cerebrovascular outpatient unit, 176 had cerebrovascular disorder diagnosed either by computed tomography (CT; n=126) or by the clinical signs. Of these, 15% were cognitively impaired and 5% fulfilled the criteria of dementia. The mean age of the patients with cognitive impairment was significantly higher than that of patients with normal cognition (68.2+/-10.2 and 60.5+/-10.5 years, P<0.001). The Barthel index was significantly lower in the cognitively affected group than in non-affected patients (92.4+/-16.0 and 97.1+/-8.7, P=0.027). Diabetes and more than two subcortical infarcts on CT or magnetic resonance imaging were more frequent in patients with cognitive loss (P=0.043 and P=0.013, respectively). Cognitive performance was also influenced by the level of education. Higher age, diabetes, motor deficits, and multiple subcortical infarcts are risk factors for cognitive impairment after stroke. The combined checklist appears to be a practical screening test for cognitive impairment in patients with chronic cerebrovascular diseases.

Age Distribution↗

Screening for depressive symptoms among post-stroke outpatients in Eastern Hungary.

Patients were consecutively enrolled in a cross-sectional study to determine the severity of depressive symptoms and the rate of treated depression in a patient population returning to a stroke outpatient service during a 10-week period for a regular check-up examination after their stroke. Of the 143 stroke patients, 119 fulfilled the inclusion criteria. The 13-item Beck Depression Inventory was used to screen for depressive symptoms. The score was at least 5 in 53%, 10 or above in 26%, and 15 or above in 11% of patients. Severity of depressive symptoms did not depend on gender, age, time elapsed from stroke, or the site of the cerebral lesion. Most patients with considerable depressive symptoms did not receive antidepressant medication at the time of the screening.

Adult↗

Absence of host-site influence on angiogenesis, blood flow, and permeability in transplanted RG-2 gliomas.

The host site is believed to regulate tumor angiogenesis, which could result in site-dependent drug delivery parameters, greatly affecting experimental tumor research. In RG-2 rat gliomas we measured cellular proliferation; cell cycle time was the same for RG-2 cells in brain and s.c. tumors (25 h), and was the same for endothelial cells in these tumors (46 h). We measured the transcapillary transfer constant (K) of alpha-aminoisobutyric acid and blood flow (F) with iodoantipyrine in RG-2 gliomas transplanted into brain, liver, kidney, muscle, s.c. tissue, and into the abdominal cavity. Data was evaluated by quantitative autoradiography and direct tissue sampling. The variation of F (12.6-84.0 ml/g/min) and K (26.1-49.2 microl/g/min) in RG-2 tumors in the different host sites was less than in surrounding tumor-free tissue (F = 20-1500 ml/g/min and K = 1.6-700 microl/g/min). In contrast to other models, RG-2 does not result in tumors with host site-dependent behavior. The RG-2 tumor cells appear to participate in, if not dominate, the angiogenesis process regardless of the host site. Values of F and K were more dependent on tumor topography (center versus periphery) and local histological features (necrosis versus viable tumor) than host site. We believe that the methods used for data acquisition may introduce as much variability in Results as the tumors themselves and that to better understand how tumor angiogenesis affects the vascular phenotype, comparative studies are needed to validate the results obtained with newer methodologies.

Algorithms↗

[Hemostatic abnormalities in ischemic stroke].

The authors studied whether haemostatic abnormalities connected with the development of cerebral circulatory disturbances can be demonstrated in young stroke patients in whom Doppler and angiographic examination failed to reveal deviations indicative of stroke. They determined the in vivo activation of the coagulation system (TAT, F 1 + 2), the degree of secondary fibrinolysis (D-dimer), the plasma levels of the markers of fibrinolysis, with special regard to inhibitors: plasminogen activator inhibitor (PAI-1), alpha 2 antiplasmin (alpha 2 AP), alpha 2 macroglobulin (alpha 2 M), the frequency of pathologic serum lipoprotein (a)-Lp(a)-values and the association of PAI-1 and Lp(a) with the fibrinolytic system. They conclude that in the acute phase of the disease, the TAT and F 1 + 2 values were significantly elevated compared to the control, without change in the D-dimer value. The results suggest that in the tested period increased thrombin generation dominated and it significantly surpassed plasmin activity since the D-dimer values of that period did not indicate substantial increase in secondary fibrinolysis. The results of the study were separately analyzed in acute, chronic TIA and stroke groups. In the TIA and acute group the F 1 + 2 values, while in stroke the TAT values were more elevated. The in vitro fibrinolytic capacity of the patients significantly decreased compared to controls, showing significant correlation with the Lp(a) level, but not with the PAI value. Examination of the marker molecules renders possible to assess the degree of hypercoaguability and of endogenous lysis. Their knowledge is held important for judging the progression of the disease and the therapeutic consequences.

Adult↗

Cerebral effects of a single dose of intravenous vinpocetine in chronic stroke patients: a PET study.

The effects of vinpocetine (Cavinton) on the cerebral glucose metabolism of chronic stroke patients are studied with positron emission tomography. The regional and global cerebral metabolic rates of glucose (CMRglu) and the kinetic constants related to them are quantified before and after single-dose intravenous vinpocetine treatment. These measurements are completed with transcranial Doppler sonography and single photon emission computed tomography to explore the possible mechanisms underlying the resulting changes in glucose uptake and metabolism in the brain. The authors' findings indicate that a single-dose vinpocetine treatment, although it does not affect significantly the regional or global metabolic rates of glucose, improves significantly the transport of glucose (both uptake and release) through the blood-brain barrier in the whole brain, the entire contralateral hemisphere, and in the brain tissue around the infarct area of the symptomatic hemisphere. These changes are in accord with increased blood flow in the entire contralateral hemisphere as well as decreased blood flow velocity and increased peripheral vessel resistance in the entire symptomatic hemisphere.

Aged↗

Effect of i.v. dipyridamole on cerebral blood flow, blood pressure, plasma adenosine and cAMP levels in rabbits.

In response to intravenous administration of dipyridamole, the quantitative and temporal changes in plasma adenosine and cyclic AMP (cAMP) levels in relation to the changes in cerebral blood flow (CBF) and mean arterial blood pressure (MABP) have not been studied. Therefore, we investigated simultaneously the changes in CBF (hydrogen and thermal clearance methods), MABP, plasma adenosine (HPLC) and cAMP (radioimmunoassay) levels for 1 h after intravenous injection of 0.7 and 1.4 mg/kg dipyridamole in rabbits. In separate experiments, only plasma adenosine concentrations were measured to determine how and for how long intravenous administration of 0.7 mg/kg dipyridamole is able to inhibit the removal of plasma adenosine. Dipyridamole decreased MABP, increased plasma adenosine and cAMP levels in a dose-dependent manner. The dose-dependency of increases in CBF could not be demonstrated owing to the marked hypotension. The increase in plasma adenosine concentrations was biphasic. The first peak could be detected at the end of the dipyridamole injection. The second peak occurred 20 min after drug administration, simultaneously with the maximal increases in plasma cAMP level and CBF, whereas the maximal fall in MABP developed earlier. Intravenous administration of 0.7 mg/kg dipyridamole inhibited adenosine uptake only by 25%, which lasted less than 10 min. We concluded that intravenously given dipyridamole is responsible only for the initial short-lasting elevation of plasma adenosine concentration, and is able to induce vasodilation without either dipyridamole itself or adenosine necessarily gaining access to the muscular layer.

Adenosine↗