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Biomedical subjects

I Németh

Publications and source records attributed to I Németh.

At least 37 records · Page 2Linked to original sources
PubMed1997

The pathogenetic role of heme in pregnancy-induced hypertension-like disease in ewes.

Toxicosis syndrome of fasting pregnant ewes has a close similarity to human preeclampsia (hypertension, albuminuria). The common etiological factor might be oxidative hemolysis and heme-induced endothelial damage. Ewes (5 starving, 5 control) at 130-135 gestational days with a 96-h fasting period followed by refeeding were used. Blood pressure, platelet count, electrolytes, kidney and liver function parameters, as well as plasma glucose, hemoglobin/heme, free thiol groups and Trolox equivalent antioxidant capacity, and plasma iron and ferritin levels were measured. Statistical significance was assessed using Student's t test (P < 0.05). Besides hypertension and renal disturbances, hemolysis, elevated liver enzymes and low platelet count, characteristic of human HELLP syndrome, were also present. In the first 24 h of glucose deprivation there was a significant rise in both the plasma hemoglobin/heme and indirect bilirubin concentrations. The antioxidant free thiol levels decreased significantly the next day, without any change in the total antioxidant capacity of the plasma. While the loss of calcium and magnesium levels related to the similarity to preeclampsia, reduced plasma iron concentrations referred to species differences in iron homeostasis. An oxidative stress causing hemolysis in a glucose-6-phosphate dehydrogenase-deficient animal model was proven by the loss of free thiols after glucose deprivation. The activation of the oxidative stress protein heme oxygenase was a signal of endothelial cell injury, the primary cause of pregnancy-induced hypertension.

Animals↗
PubMed1997

Oxidative stress and antioxidant defense mechanism in glomerular diseases.

The changes in red blood cell (RBC) lipid peroxidation [measured via the malonyl dialdehyde (MDA) concentration], reduced (GSH), and oxidized glutathione (GSSG) levels, hemoglobin (Hb) oxidation and antioxidant enzyme [catalase (Cat), glutathione peroxidase, and superoxide dismutase (SOD)] activities were studied in 45 pediatric patients with various glomerular diseases [minimal change nephrotic syndrome (MCNS) in relapse or in remission, lupus nephropathy (SLE), poststreptococcal glomerulonephritis (APSGN), IgA nephropathy (IGA gn)], and in 20 adult patients with IGA gn and also in 15 pediatric and 14 adult controls. The in vitro effects of hydrogen peroxide [acetyl phenylhydrazine (APH) test] on the GSH and Hb metabolisms were likewise investigated. There was an increased oxidative stress in MCNS with relapse, IGA gn, SLE gn, and APSGN, which could be detected in the GSH and Hb oxidation and in the lipid peroxidation on the peripheral RBC-s. The RBC SOD and Cat activities were significantly lower in all patients than in the controls. The RBC GSSG level was significantly elevated in all patients, with the exception of MCNS in remission. This stimulated a compensatory GSH production in MCNS with relapse and in IGA gn, but not in SLE or APSGN. The regeneration of GSH from GSSG was reduced in MCNS with relapse, SLE, and IGA gn, but not in APSGN. In remission, the GSH-GSSG redox system normalizes, but in vitro the APH test stimulates an intensive Hb oxidation. In conclusion, there is a correlation between the presence of active glomerular disease and the evidence of oxidative changes in the various parameters measured in peripheral RBCs.

Adolescent↗
PubMed1997

Oxidative stress induced by bloodless limb surgery on humans.

Measure of oxidative stress were studied in blood samples from 10 patients undergoing bloodless lower limb surgery. Ischaemia induced a significant increase in plasma hypoxanthine concentration and xanthine oxidase activity both in the operated leg and in the systemic circulation. Five minutes after reperfusion, ratio of xanthine oxidase/total xanthine oxidase and dehydrogenase activities rose moderately, whereas at 20 min xanthine oxidase accounted for all xanthine oxidoreductase activity in the systemic circulation. A significant increase in blood glutathione redox ratio, enhanced oxidation of haemoglobin to methaemoglobin and rise in plasma haemoglobin concentration were present only in the operated limb. Thus, although the level of the potential free radical generators rose significantly both locally and in the systemic circulation, oxidative stress, as indicated by blood glutathione and erythrocyte injuries, remained limited to the reperfused leg.

Aged↗
PubMed1996

Serological survey on the prevalence of chicken anaemia virus infection in Hungarian chicken flocks.

A serological survey on the prevalence of chicken anaemia virus (CAV) infection was performed by using the indirect immunofluorescence (IF) and the virus neutralization (VN) tests in commercial Hungarian chicken populations. By the indirect IF test, a total of 846 serum samples from 13 meat-type parent flocks of two breeds were investigated between 10 and 62 weeks of age. All flocks were found to be positive for anti-CAV antibodies, and the rates of antibody-positive birds among flocks ranged from 40 to 93.3% and with an average of 73.3%. From nine 1-day- to 9-week-old progeny broiler flocks, 96 serum samples were tested. In the 3 flocks, sampled at the hatchery, 75 to 100% (average 86.4%) of the 22 tested birds were antibody positive. From the 6 flocks, tested between 4 to 9 weeks of age, 3 were antibody negative at 4 and 5 weeks of age, whereas in the 3 remaining 6- to 9-week-old flocks 10 to 20% (average 13.5%) of the birds were antibody positive. In egg-laying parent flocks of 14 and 35 weeks old, 54.4 and 71.7% of the tested 79 and 46 birds had antibodies to CAV, respectively. By the VN test, a total of 670 serum samples from 9 meat-type parent flocks aged between 11 and 37 weeks were investigated. The rate of antibody positivity in flocks was always over 80% and averaged 90.9%. From 7 progeny broiler flocks, 261 serum samples were tested between one day and 7 weeks of age, and the rates of seropositivity in flocks were between 93.3 to 100% and averaged 96.9%. In an egg-laying parent flock, 89.2% of the tested 102 birds had neutralizing antibodies to CAV at 35 weeks old. It was concluded that CAV is widespread in Hungarian commercial chicken populations. Though, according to simultaneous examination of 195 flock sera, the VN test revealed 11.3% more antibody-positive birds, the indirect IF test was found suitable for serological surveys at flock(s) level, provided that sufficient numbers of individual chicks were tested.

Animals↗
PubMed1994

Oxidative damage of red blood cells in haemolytic uraemic syndrome.

Changes in red blood cell (RBC) lipid peroxidation [measured by malonyl dialdehyde (MDA) concentration], glutathione (GSH) metabolism, antioxidant enzyme activities (catalase, superoxide dismutase, glutathione peroxidase) and haemoglobin (Hb) metabolites (metHb, carboxy Hb) were studied in six children with post-enteropathic (D+) haemolytic uraemic syndrome (HUS) and ten controls. The in vitro effect of hydrogen peroxide [acetylphenylhydrazine (APH) test] on GSH and Hb metabolism was also investigated. MDA levels were significantly higher and the antioxidant enzyme activities were lower in HUS patients than in the controls (P < 0.01). The oxidised glutathione concentration was significantly higher in the patients than in the control children (26.3 +/- 12.6 vs. 10.9 +/- 1.8 nmol/g Hb. Percentage values of carboxy Hb and metHb were also higher in HUS (P < 0.01). Incubation of RBC with APH induced a more pronounced decrease in the concentration of GSH (P < 0.001) and a significant increase (P < 0.01) in the level of metHb and carboxy Hb in the HUS patients. This suggests that there is reduced RBC GSH stability in HUS. Utilisation of GSH and antioxidant enzymes leads to increased Hb oxidation and haemolysis. The oxidative damage may have an important role in the pathogenesis of haemolytic anaemia in HUS.

Adolescent↗
PubMed1994

Blood glutathione redox ratio as a parameter of oxidative stress in premature infants with IRDS.

Oxygen toxicity is thought to play an important pathogenic role in several neonatal diseases, including idiopathic respiratory distress syndrome (IRDS). Therefore, the development of a reliable measure of the actual oxidative stress status of patients would be of great clinical significance. In order to obtain information about the oxidative stress during the first week of life in premature infants with IRDS, the blood concentrations of oxidized and reduced glutathione, as well as their molar ratios, were determined by a highly sensitive, specific enzymic assay. The fractional inspired oxygen concentrations needed to maintain adequate arterial oxygen tension and the arterio-alveolar oxygen ratios were chosen as parameters indicating the severity of illness in premature infants at a given time. There was a highly significant positive correlation between the glutathione redox ratios and the fractional inspired oxygen concentrations. A maturity-related difference was also found; the oxidized glutathione concentrations were the highest in the least mature infants, accompanied by a pronounced compensatory rise in the reduced glutathione concentrations as well. A significant negative correlation was found between the arterio-alveolar oxygen ratio and the glutathione redox ratio: i.e., an improvement in oxygenation was accompanied by a decrease in the glutathione redox ratio. The efficient recycling of reduced glutathione in erythrocytes providing antioxidant protection for premature infants, permits the use of the blood glutathione redox ratio as a noninvasive measure of in vivo oxidative stress.

Antioxidants↗
PubMed1993

[Retrospective biochemical study of the preventive property of antioxidants in retinopathy of prematurity].

Oxygen radical injury may be one of the factors leading to Retinopathy of Prematurity. It occurs when the body's natural antioxidant capacity is overwhelmed by the free oxygen radicals produced during the perinatal period. Supposing, that premature infants may have defects in their antioxidant systems which can be detected later, even in childhood, a retrospective study of 36 patients of different ages (born prematurely) suffering from different stages of Retinopathy of Prematurity was carried out. According to our results, the signs of an acute oxidative stress could only be seen in the 3 month-old patients' erythrocyte glutathione redox system which was independent of the clinical severity of retinopathy. However, following an in vitro oxidative stress an increased susceptibility of erythrocytes was found in all our patient groups, which means, that the ratio of residual and original amounts of reduced glutathione was decreased and the amount of oxidated derivates of haemoglobin was increased. As selenium is an integral part of glutathione peroxidase enzyme, the very low selenium levels measured in all of our patient groups indicate a reduced glutathione peroxidase activity. The present study suggests, that selenium depletion even in Hungary might play an important role in the pathogenesis of Retinopathy of Prematurity.

Antioxidants↗
PubMed1992

The effect of erythropoietin on the cellular defence mechanism of red blood cells in children with chronic renal failure.

The glutathione redox system, haemoglobin (Hb) oxidation, the activity of antioxidant enzymes and the lipid peroxidation product malonyl dialdehyde (MDA) were studied in red blood cells (RBCs) during administration of recombinant human erythropoietin (rhEPO) over 12 weeks in ten children maintained on haemodialysis. A rapid increase in the reticulocyte count was accompanied by a slower rise in total Hb concentration. The mean level of oxidized glutathione (GSSG) increased from 13.2 +/- 5.3 nmol/g Hb to 56.7 +/- 15.8 nmol/g Hb 4 weeks after the start of rhEPO (P < 0.001), followed by a fall to the basal value. Reduced glutathione (GSH) levels showed a smaller though constant elevation during rhEPO therapy (P < 0.001). Before rhEPO treatment, incubation of RBCs for 1 h with acetylphenylhydrazine induced a decrease in GSH concentration compared with controls (P < 0.001), which became more pronounced in the first few weeks of rhEPO therapy (P < 0.001). In addition, the percentage of Hb derivatives (metHb and haemichrome) increased in the first 4 weeks of rhEPO therapy (P < 0.001). Although there was no significant difference between the values obtained preEPO and during EPO treatment, MDA levels were continuously higher and superoxide dismutase, catalase and glutathione peroxidase concentrations were lower than in the controls (P < 0.001). These results are compatible with oxidative damage to the RBCs in the early period of rhEPO therapy in children with end-stage renal failure. The GSH-GSSG system, as an important cellular defence mechanism of the RBCs, appears to be severely affected.

Adolescent↗
PubMed1992

Isolation of chicken anaemia virus from broiler chickens.

Chicken anaemia virus (CAV) infection was demonstrated, by both serology and virus isolation, in 1- to 6-week-old broiler chickens originated from various parent flocks in Hungary. Total losses in the broiler flocks were estimated at 7 to 8% and about 25% of the chickens failed to reach target body mass by the 7th week of life. The clinical signs, postmortem lesions and histopathological changes of the affected chickens were similar to those of naturally occurring CAV-induced infectious anaemia of young chickens. In MDCC-MSB1 cell cultures, a chloroform-resistant virus smaller than 50 nm in diameter, resistant to heating at 70 degrees C for 30 min, and antigenically very closely related to the Cux-1 strain of CAV was isolated from the liver of naturally diseased broilers. This virus isolate was designated the Bia strain of CAV. Inoculation of susceptible 1-day-old SPF chicks with a CAV-positive liver extract from naturally diseased broilers caused pathological changes characteristic of CAV infection, namely impaired growth, severe anaemia with atrophy of the bone marrow, marked atrophy of the lymphoid organs and petechial haemorrhages throughout the body. A quite similar pathological syndrome was also induced by inoculation of 1-day-old SPF chicks with the MDCC-MSB1 cell-culture-propagated new Bia strain of CAV. The CAV was successfully reisolated from the livers of experimentally inoculated birds, and antibodies to the reference Cux-1 strain of CAV were also demonstrated by the indirect immunofluorescence test in sera of naturally diseased and experimentally inoculated chickens. No antibodies were found against infectious bursal disease virus, reticuloendotheliosis virus, Marek's disease herpesvirus as well as avian adenoviruses and reoviruses. The reported disease of young broiler chickens was associated with natural infection of a new isolate of CAV. On the basis of its physicochemical, antigenic and pathogenic characteristics, this virus is similar to other strains of CAV isolated from chickens in other countries.

Anemia↗
PubMed1992

Decrease in the antioxidant capacity of red blood cells in children with celiac disease.

The erythrocyte glutathione metabolism of 11 children with acute celiac disease (CD), 11 children under gluten free diet with CD and 5 children with cow's milk allergy was compared to that of 11 children with nutritive iron deficiency and to 22 healthy children as controls. Erythrocyte glutathione (GSH) content of celiac children was elevated and the glutathione disulfide (GSSG) level was significantly decreased as compared to normal controls. Erythrocyte GSSG/GSH ratio in acute CD differed also from the one in iron deficiency. In vitro oxidative load of acetylphenylhydrazine proved the impaired glutathione stability of the erythrocytes in acute CD and cow's milk allergy. A parallel rise of methemoglobin and hemichrome level of blood cells was seen. Further on, the selenium content of the red blood cells of CD patients decreased. All alterations of the erythrocyte tended to normalize during the dietetic period. These data suggest a reduced protective capacity of erythrocytes in CD and in cow's milk allergy in childhood against oxidizing stresses.

Celiac Disease↗
PubMed1991

Examination of the role of oxygen free radicals in bronchial asthma in childhood.

The antioxidant enzyme activities, the lipid peroxidation level, the parameters of glutathione metabolism, and the proportion of haemoglobin oxidation products were determined during the symptom-free period of childhood bronchial asthma. A decreased catalase activity and a significantly reduced glutathione instability were demonstrated as compared to the controls. The results indicate that antioxidant protection of the haemoglobin molecule in asthmatic children is considerably decreased.

Adolescent↗
PubMed1991

Erythrocyte defense mechanisms against free oxygen radicals in haemodialysed uraemic children.

Changes in erythrocyte lipid peroxidation (measured as the concentration of malonyl dialdehyde), glutathione metabolism, antioxidant enzyme activities (glutathione peroxidase, catalase, and superoxide dismutase), the oxidized products of haemoglobin (Hb), and hydrogen peroxide (H2O2)-induced haemolysis were studied in six children with chronic renal failure treated with serial acetate and bicarbonate haemodialysis (HD). Ten age- and sex-matched children acted as controls. Malonyl dialdehyde levels were significantly higher and antioxidant enzyme activities lower in uraemic red blood cells (RBCs) compared with controls (P less than 0.05). Incubation of RBCs for 1 h with acetylphenylhydrazine induced a decrease in the concentration of reduced glutathione (P less than 0.001) and an increase in the level of oxidized products of Hb (P less than 0.001), but only in the uraemic patients. The H2O2 haemolysis test revealed a mild (n = 3) to increased (n = 3) haemolysis in the uraemic RBCs. Oxidative haemolysis is probably a multifactorial process in uraemic patients, and may be an important risk factor in HD therapy.

Adolescent↗
PubMed1989

[Selenium levels in erythrocytes of children with celiac disease].

Selenium is the component of the glutationperoxidase one of the most important enzymes in the antioxidant protection of the organism. In preliminary studies the authors found in celiac children increased sensitivity to oxidative stress and biochemical changes referring to decreased activity of glutationperoxidase enzyme. Therefore the selenium content of washed erythrocytes has been determined with fluorimetry in 24 celiac children kept on gluten containing diet and 25 on gluten-free diet. In gluten loading the selenium level was significantly lower than in the healthy control group. The selenium value rose at a small degree in the erythrocytes of celiac children kept on gluten-free diet but did not reach the lower limit of the physiological value. On the basis of these results the malabsorption of selenium was found to play also an important role in the decreased protecting capacity against oxidative stress effects in celiac diseases of childhood. The necessity of supplementing the trace element is raised.

Celiac Disease↗
PubMed1989

Measurement of urinary caffeine metabolites reflecting the "in vivo" xanthine oxidase activity in premature infants with RDS and in hypoxic states of children.

Grant et al. have demonstrated that after caffeine intake the ratio of 1-methyluric acid (MU) and 1-methylxanthine (MX) in the urine indicates the total xanthine oxidase (XO) activity of the organism. It has been stated - after having applied this method on premature infants with severe respiration distress syndrome (17 cases) and on children in need of intensive care (18 cases) in the critical phase and during the reparation of the same patients as well, furthermore on so-called shock-tolerant patients (6 cases) and on healthy children (15 cases) - that the total XO activity can increase extremely in severe acute clinical states but a considerable decrease can be detected during reparation while in shock-tolerant states it can become expressively low. The investigations explain properly the favourable XO inhibiting effect of allopurinol demonstrated in states of experimental and clinical shock. The low XO activity observed in shock-tolerant conditions may be the result of intrinsic compensatory mechanisms.

Biomarkers↗
PubMed1989

The ratio of oxidized/reduced glutathione as an index of oxidative stress in various experimental models of shock syndrome.

Red blood cells are well equipped to handle intracellular oxidative stress, their membranes are permeable to O2- and H2O2, and in this way they are important regulators of oxygen reactions occurring in their surroundings. The protective effect against reduced oxygen species - generated during the endothelial cell injury of various tissues - is attributed mainly to the glutathione metabolism of red blood cells. The blood concentration of reduced (GSH) and oxidized glutathione (GSSG) was determined by a sensitive method using glutathione reductase in experimental shock syndromes induced by paraquat toxicity, tourniquet ligature and endotoxin in rats, by bleeding and reperfusion in dogs and by transient ligature of thoracic aorta in newborn piglets. Under these conditions the concentration of GSSG was elevated and GSH was lowered, resulting in an increase in the redox ratio: [GSSG/(GSH + GSSG)] x 100 (GSSG/GSH); particularly during reperfusion. Determination of the GSSG/GSH seems to be a reliable index to assess the degree of oxidative stress "in vivo".

Animals↗