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Biomedical subjects

G Tamás

Publications and source records attributed to G Tamás.

At least 19 recordsLinked to original sources
PubMed2006

Influence of ozone-limonene reactions on perceived air quality.

UNLABELLED: This study conducted short-term assessments of perceived air quality (PAQ) for six different realistic concentrations of ozone and limonene, separately or together, in room air. The impact of filtration and the influence of the ozone generation method were also examined. The evaluations were made in four identical 40 m3 low-polluting test offices ventilated at 1.4 h(-1) or in two identical 30 m3 stainless-steel chambers ventilated at 1.9 h(-1). Concentrations of ozone, total volatile organic compounds and size-fractionated particles were continuously monitored in each experiment. The results indicate that, for each of the six conditions, the PAQ was poorer when ozone and limonene were present together compared with when only ozone or only limonene was present. In the test offices a correlation was observed between the number of secondary organic aerosols produced by a given ozone/limonene condition and the sensory pollution load for that condition. The particles themselves do not appear to be the primary causative agents, but instead are co-varying surrogates for sensory offending gas-phase species. PRACTICAL IMPLICATIONS: Although the health consequences of long-term exposures to the products of ozone-initiated indoor chemistry remain to be determined, we judge that the sensory offending nature of selected products provides an additional reason to limit indoor ozone levels. Devices that emit ozone at significant rates should not be used indoors. Ozone-filtration of make-up air should also be beneficial in mechanically ventilated buildings located in regions that repeatedly violate outdoor ozone standards. Additionally, the use of limonene containing products should be curtailed during periods when indoor ozone levels are elevated.

Aerosols↗
PubMed2001

Beta and gamma frequency synchronization by dendritic gabaergic synapses and gap junctions in a network of cortical interneurons.

Distinct interneuron populations innervate perisomatic and dendritic regions of cortical cells. Perisomatically terminating GABAergic inputs are effective in timing postsynaptic action potentials, and basket cells synchronize each other via gap junctions combined with neighboring GABAergic synapses. The function of dendritic GABAergic synapses in cortical rhythmicity, and their interaction with electrical synapses is not understood. Using multiple whole-cell recordings in layers 2-3 of rat somatosensory cortex combined with light and electron microscopic determination of sites of interaction, we studied the interactions between regular spiking nonpyramidal cells (RSNPCs). Random samples of unlabeled postsynaptic targets showed that RSNPCs placed GABAergic synapses onto dendritic spines (53 +/- 12%) and shafts (45 +/- 10%) and occasionally somata (2 +/- 4%). GABAergic interactions between RSNPCs were mediated by 4 +/- 2 axodendritic synapses and phased postsynaptic activity at beta frequency but were ineffective in phasing at gamma rhythm. Electrical interactions of RSNPCs were transmitted via two to eight gap junctions between dendritic shafts and/or spines. Elicited at beta and gamma frequencies, gap junctional potentials timed postsynaptic spikes with a phase lag, however strong electrical coupling could synchronize presynaptic and postsynaptic activity. Combined unitary GABAergic and gap junctional connections of moderate strength produced beta and gamma frequency synchronization of the coupled RSNPCs. Our results provide evidence that dendritic GABAergic and/or gap junctional mechanisms effectively transmit suprathreshold information in a population of interneurons at behaviorally relevant frequencies. A coherent network of GABAergic cells targeting the dendrites could provide a pathway for rhythmic activity spatially segregated from perisomatic mechanisms of synchronization.

Action Potentials↗
PubMed2001

Glycaemic control in type 1 diabetic patients using optimised insulin aspart or human insulin in a randomised multinational study.

Insulin aspart (IAsp), is a rapid-acting analogue of human insulin (HI), for use in the meal related treatment of diabetes mellitus. The degree of glycaemic control achieved by IAsp in comparison with HI after algorithm-driven dose optimisation was tested over 3 months. The prospective, multicentre, randomised, open-label study with parallel groups was performed in 48 centres in 11 countries and included 423 basal-bolus treated patients with Type 1 diabetes. Main outcome measures were blood glucose control assessed by HbA1c, nine-point self-monitored blood glucose profiles, insulin dose, quality of life, hypoglycaemia and adverse events. An algorithm-driven increase occurred in the dose and number of daily injections of basal insulin, particularly in the IAsp group. After 12 weeks of treatment, HbA1c was significantly lower in IAsp compared to HI treated subjects by 0.17 (95% CI 0.30-0.04) (P<0.05). Comparison of the blood glucose profiles showed lower blood glucose levels with IAsp after breakfast (mean 8.4 vs 10.1 mmol/l; P<0.0001) and dinner (8.2 vs 9.3 mmol/l; P<0.01). There were no differences between treatments in the incidence of hypoglycaemic episodes or in the adverse event profiles. The WHO Diabetes Treatment Satisfaction Questionnaire score for perceived hyperglycaemia was lower with Iasp (P=0.005), and patients found the insulin aspart treatment more flexible (P=0.022). The current study underlines the need for optimising the basal insulin regimen in order to take full advantage of the pharmacodynamics of IAsp.

Adult↗
PubMed2001

Gestational diabetes: current aspects on pathogenesis and treatment.

Gestational diabetes (GDM) is a carbohydrate intolerance resulting in hyperglycaemia of variable severity with onset or first recognition during pregnancy. The incidence of GDM is between 0.15-15%, which corresponds to the prevalence of type 2 diabetes and IGT in a given country.--The predominant pathogenic factor in GDM could be the inadequate insulin secretion. If GDM is not properly treated the risk of adverse maternal (preeclampsia) and fetal (large-for-gestational-age infant, macrosomia, birth trauma, cesarean section, still-birth) outcome increases. Hypertension is more prevalent in GDM, and GDM is diagnosed more frequently in women with chronic hypertension.--In order to screen for disturbances of carbohydrate metabolism during pregnancy a simple method suitable for all pregnant women would be desirable, however no such method is available at present. According to the latest WHO recommendation the screening for GDM should be performed universally with the standard 75 g oGTT evaluating only the 2-hour blood glucose values or together with the fasting ones. The latter could provide even an exact diagnosis of the carbohydrate metabolic state.--To manage GDM the first step prompt after diagnosis is to educate adequate dietary needs. If the blood sugar values in spite of an adequate diet exceed the desirable target values, insulin treatment has to be initiated.--GDM is a predictor of diabetes (mainly type 2) later in life. The cumulative incidence of type 2 diabetes is about 50% at 5 years. This review of the current literature including our own experience strongly supposes that prior GDM is also a predictor or even an early manifestation of the metabolic (insulin resistance) syndrome. By all means GDM is a cardiovascular risk factor that could be screened to prevent late complications. The previously presented evidence also strongly suggests that yearly check-ups for women with previous GDM are inevitably important.

Diabetes, Gestational↗
PubMed2001

Blood pressure response to standing in the diagnosis of autonomic neuropathy: the EURODIAB IDDM Complications Study.

Autonomic neuropathy is associated with poor prognosis. Cardiovascular reflexes are essential for the diagnosis of autonomic nerve dysfunction. Blood pressure response to standing is the most simple test for the evaluation of sympathetic integrity, however it is still discussed which diagnostic criteria of abnormal response should be considered as optimal. The EURODIAB IDDM Complications Study involved the examination of randomly selected Type 1 diabetic patients from 31 centres in 16 European counties. Data from 3007 patients were available for the present evaluation. Two tests of autonomic function (response of heart rate /R-R ratio/ and blood pressure from lying to standing) just as the frequency of feeling faint on standing up were assessed. R-R ratio was abnormal in 24% of patients. According to different diagnostic criteria of abnormal BP response to standing (>30 mmHg, >20 mmHg, and >10 mmHg fall in systolic BP), the frequency of abnormal results was 5.9%, 18% and 32%, respectively (p < 0.001). The frequency of feeling faint on standing was 18%, thus, it was identical with the prevalence of abnormal blood pressure response to standing when >20 mmHg fall in systolic blood pressure was considered as abnormal. Feeling faint on standing correlated significantly with both autonomic test results (p < 0.001). A fall >20 mmHg in systolic blood pressure after standing up seems to be the most reliable criterion for the assessment of orthostatic hypotension in the diagnosis of autonomic neuropathy in patients with Type 1 diabetes mellitus.

Adolescent↗
PubMed2000

Research training between 14 and 18 in Hungary.

The first five years of a new program to organize high-level scientific research training for gifted high school students in Hungary are described. Besides giving unique research opportunities for talented students in their most receptive age, the program already helped the establishment of almost 100 scientific research clubs in Hungarian high schools, provided a focal point for science training of high school teachers and helped regional cooperation in Central-Eastern Europe.

Journal Article↗
PubMed2000

Proximally targeted GABAergic synapses and gap junctions synchronize cortical interneurons.

Networks of GABAergic interneurons are implicated in synchronizing cortical activity at gamma frequencies (30-70 Hz). Here we demonstrate that the combined electrical and GABAergic synaptic coupling of basket cells instantaneously entrained gamma-frequency postsynaptic firing in layers 2/3 of rat somatosensory cortex. This entrainment was mediated by rapid curtailment of gap junctional coupling potentials by GABAA receptor-mediated IPSPs. Electron microscopy revealed spatial proximity of gap junctions and GABAergic synapses on somata and dendrites. Electrical coupling alone entrained postsynaptic firing with a phase lag, whereas unitary GABAergic connections were ineffective in gamma-frequency phasing. These observations demonstrate precise spatiotemporal mechanisms underlying action potential timing in oscillating interneuronal networks.

Action Potentials↗
PubMed2000

Targets and reality: a comparison of health care indicators in the U.S. (Pittsburgh Epidemiology of Diabetes Complications Study) and Hungary (DiabCare Hungary).

OBJECTIVE: In the U.S., both primary care and specialist physicians share in the care of type 1 diabetic patients, often in an informal collaboration. In Hungary, however, type 1 diabetic patients are generally managed in special centralized diabetes units. These different treatment settings may lead to different health care practices and outcomes. To determine if this is true, diabetes care indicators and complications were compared across representative study populations from the 2 countries. RESEARCH DESIGN AND METHODS: The Pittsburgh Epidemiology of Diabetes Complications Study (EDC) is a prospective cohort of childhood-onset type 1 diabetic patients. DiabCare Hungary, a multicenter cross-sectional study, was developed for quality control purposes and provides a nationwide data set of diabetic patients. We identified 2 comparable populations (EDC, n = 416; DiabCare, n = 405) in terms of age (> or =14 years) and age at onset (<17 years). RESULTS: EDC patients were less likely to receive diabetes education (P<0.0001), see an ophthalmologist (P<0.0001), be treated by diabetologists (P<0.0001), or perform self-monitoring of blood glucose (P<0.0001). They were more likely to use conservative insulin regimens (i.e., 1-2 injections/day, P<0.0001) and have a higher glycated hemoglobin (P< 0.0001). DiabCare patients more often experienced severe hypoglycemia (P<0.01) and had a lower prevalence of proliferative retinopathy (P<0.0001), legal blindness (P<0.05), and albuminuria (> or =30 mg/day P<0.01). No significant differences in macrovascular complications were seen, although rates were generally low CONCLUSIONS: These data suggest that the 2 populations differ by their diabetes care practices, degree of glycemic control, and microvascular complication status.

Adolescent↗
PubMed1999

[Detection of antibodies against pancreatic islet cells in clinical practice].

Development of diabetes mellitus caused by pancreatic beta-cell destruction of autoimmune origin is the result of a long lasting process. The most easily examinable feature of this stage is the occurrence of the islet cell antibodies. The sera which are positive for islet cell cytoplasmic antibodies (ICA), examined by indirect immunofluorescence, contain a mixture of antibodies. The glutamic acid decarbocylase (GAD), the tyrosin phosphatase (IA2), the insulin, and the GM2-1 glycolipid can be the targets of these antibodies. One can routinely examine the ICA, the GADA, the IA2 antibodies. The detection of antibodies against insulin (IAA) and GM-2-1 glycolipid is not invented in the routine laboratory work. The aim of the authors was the evaluation of clinical significance of occurrence of islet cell antibodies: one hundred and eighteen nondiabetic children an adult human being without known diabetic first degree relatives and 366 type 1 diabetic children and adult patients served as controls. The authors evaluated the predictive value of the different islet cell antibodies to the development of type 1 diabetes mellitus in 596 nondiabetic children with type 1 diabetic first degree relatives. The authors looked for markers of beta-cell destruction among sera of 320 diabetics manifested after 30 years of age with at least half a year of non-insulin-dependency and in the sera of 68 females suffered from gestational diabetes after 0-14 years of the index pregnancy. Finally the authors report 7 cases in which the examination of islet cell antibodies helped the diagnosis and classification of diabetes mellitus. Indirect immunofluorescence method was used for the detection of ICA, radioimmunoassay for that of GADA and IA2 antibodies. There was no positive reaction for ICA and GADA in the nondiabetic population without diabetic first degree relatives. Among the freshly diagnosed type 1 diabetic children 39% were positive for only ICA, 44% for only GADA and 80% for any antibodies. Among the freshly manifested type 1 diabetic adults ICA positivity only was observed in 21%, GADA positivity only in 7.1% and 93% for any antibodies. From the 595 nondiabetic children with type 1 diabetic first degree relatives 23 were positive for ICA, from whom 5 became diabetic during a two years observation period. These diabetic children had multiplex autoantibodies besides ICA. One child from this group, who was negative for ICA became diabetic, too. Among type 2 diabetic patients 13% were positive for ICA alone, 17% were positive for GADA alone and 27% were positive for any antibodies. The insulin dependency manifested in a short time was associated with antibody positivity. Among the gestational diabetics 10 were found positive for ICA. From them, 7 were type 1 diabetics, and 3 were type 2 diabetics at the time of the detection of antibodies. The authors suggest the need of determination of islet cell antibodies in the group of nondiabetic first degree relatives of type 1 diabetic patients (ICA, GADA, IA2 and IAA), in the group of non-insulin-dependent diabetics (ICA and GADA) as a screening for later insulin dependency, and in gestational diabetes after delivery (ICA) as screening for type 1 diabetes mellitus.

Adolescent↗
PubMed1999

A case of a calcified renal cyst.

Authors review a case of a calcified renal cyst. The literary data at hand give evidence that the spreading processes in the kidney can be benign or malignant according to their form of calcification and their localisation. Despite the modern diagnostic techniques, it is not easy to set up the diagnosis or to avoid the need for surgery, as was the case in the present report.

Aged↗
PubMed1999

Anatomic variations in patients operated for bladder substitution.

Authors review the anatomic variations observed throughout orthotopic ileal neobladder formation in 38 cases following radical cystectomy. A part of the variations was necessitated because of deviation from the classic Hautmann-type surgical technique: in 6 cases the site of ileal resection was modified due to abnormal mesenterial art. course, on 2 occasions Meckel diverticules were detected while cutting the ileal neobladder, in 13 cases the laterally adhered sigma bladder necessitated the left-sided ureter to be pulled through beneath the mesosigma for the purpose of making sure the ureter--ileal neobladder anastomosis became free of any tension, while on 1 occasion the left ureteral preparations went with some injury. Since the left ureter became short, ureter replacement variation was needed, similar to the Studer method of ileal neobladder formation. All these variations, however, did not implicate the essence of the Hautmann technique. Follow-up of the patients did not reveal high frequency of occurrence of any complications.

Aged↗
PubMed1999

Comparison of morbidity of lumbar flank approach and transperitoneal approach for radical nephrectomy.

PURPOSE: This is a retrospective study comparing the clinical data and morbidity of transperitoneal radical nephrectomy (TRN) and simple nephrectomy. MATERIAL AND METHODS: From 1st January, 1989 to 1st January, 1996 a total of 90 simple nephrectomies and from 1st January, 1996 to 1st August, 1999 a number of 85 TRN were performed at the Department of Urology of the Saint Stephen Hospital. The analysis of clinical data included operative time, length of analgesics, postoperative hospital stay and blood loss, as well as morbidity. RESULTS: The mean operative time for TRN was 170 min., being 95 min. for simple nephrectomy. The mean blood loss for TRN was 250 ml, and 400 ml for simple nephrectomy. There were different types of morbidity for TRN and simple nephrectomy. The complications of TRN mean minimal risk and easy correctibility. CONCLUSION: Our results demonstrate an overall clear advantage of TRN when compared to simple nephrectomy.

Aged↗
PubMed1999

Metabolic consequences of orthotopic ileal neobladder.

PURPOSE: Orthotopic ileal bladder substitution is a well accepted form of urinary diversion providing high quality of life. However, potential metabolic consequences remain a serious problem. These complications are discussed in the present article. MATERIAL AND METHODS: Authors review the metabolic complications of 45 orthotopic ileal neobladder cases. RESULTS: Insufficient absorption (malabsorption) associated with ileal resection is quite rare, while hyperchloremic metabolic acidosis after ileal neobladder is a rather common phenomenon (55%). CONCLUSION: Authors suggest careful patient selection, correct operative technique and vigilant follow-up for successful treatment of metabolic complications.

Acidosis↗