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Biomedical subjects

I Varga

Publications and source records attributed to I Varga.

At least 73 records · Page 4Linked to original sources
PubMed1998

Detection of antibodies to Neospora caninum in bovine postabortion blood samples from Hungary.

In order to obtain data on the occurrence of the protozoan parasite Neospora caninum as a potential factor in the aetiology of reproduction problems in cattle, 97 postabortion sera were examined by ISCOM ELISA and IFAT for the presence of antibodies in N. caninum. The results showed 10% and 9% seropositivity by the ELISA and IFAT, respectively. In 2 of the 10 seropositive cases no other fetopathogenic agents (such as Chlamydia sp., Leptospira spp. or bovine viral diarrhoea virus) were detected. These data confirm the presence of N. caninum in cattle in Hungary.

Abortion, Veterinary↗
PubMed1997

[Bilateral renal artery stenosis diagnosed during pregnancy].

Bilateral renal artery stenosis was diagnosed noninvasively in the 17th gestational week, in a chronically hypertensive pregnant woman, by renal artery duplex ultrasound examination, MRI and MR angiography. Continuous monitoring of the mother and the fetus was performed. Blood pressure was stabilized by complex antihypertensive therapy, but from the beginning of the third trimester superimposed preeclampsia developed gradually. In the 34th gestational week a 1600-g newborn was delivered by elective cesarean section. The case report draws attention to the significance of the thorough examination of hypertensive women before pregnancy.

Adult↗
PubMed1997

Unique Alzheimer's disease paired helical filament specific epitopes involve double phosphorylation at specific sites.

Alzheimer's disease (AD) paired helical filaments (PHFs), building blocks of neurofibrillary tangles (NFTs) are composed of hyperphosphorylated forms of the microtubule-associated protein tau (i.e., PHF-tau). Currently, much effort is devoted to the development of diagnostic antibodies specific for PHF-tau since elevated tau levels are found in the cerebral spinal fluid of AD patients. To this end, we have mapped the epitopes of a large panel of monoclonal antibodies (mAbs) that recognized only phosphorylation dependent epitopes on PHF-tau. These mAbs include the PHF-tau specific mAb AT10 and 12 newly developed anti-PHF mAbs that recognize PHF-tau but not autopsy-derived normal adult tau on Western-blot and enzyme-linked immunosorbent assay (ELISA). Epitope analysis, together with data on known binding sites of previously published mAbs, revealed that Ser214, Thr231, and Ser396 are immunodominant phosphorylated amino acids in PHF-tau. Six of the 12 new mAbs recognized one of these three phosphorylated sites. With the exception of AT10 and PHF-27, all the mAbs also labeled fetal tau and biopsy-derived tau. Since mAbs AT10 and PHF-27 had little or no affinity for fetal tau and biopsy tau, they can be considered as the first "true" PHF-specific antibodies capable of distinguishing tau isoforms from normal versus AD subjects, suggesting a possible utility of these mAbs as diagnostic markers. Remarkably, the true PHF-specific antibodies recognized peptide sequences phosphorylated on more than one amino acid residue. The peptide recognition of mAb AT10 required the simultaneous phosphorylation of Thr212 and Ser214, and the peptide recognition of mAb PHF-27 was markedly increased when both the primary site Thr231 and the subsite Ser235 were phosphorylated. Since AT10 and PHF-27 are the only mAbs currently available that bind specifically to PHF-tau, these data suggest that double phosphorylation at Thr212/Ser214 and Thr231/Ser235 may be unique to PHF-tau. These data may facilitate the development of mAbs that can be used as specific diagnostic reagents for the detection of altered tau in cerebrospinal fluid of AD patients.

Adult↗
PubMed1997

Effect of F-2 and T-2 fusariotoxins on experimental Cryptosporidium baileyi infection in chickens.

The course of Cryptosporidium baileyi infection in chickens fed with different doses of fusariotoxins was compared with that of control groups. F-2 toxin levels of 0.187-1.5 mg kg-1 and T-2 toxin levels of 0.187-6.0 mg kg-1 were investigated. The experimental animals were orally infected with 6 x 10(5) C. baileyi oocysts at 1 week of age. Total daily oocyst output was monitored by a quantitative method. Acquired immunity was tested at the age of 4 weeks, by ELISA and by a challenge infection with an equal number of oocysts, upon recovery from the primary infection. The results show that in chickens kept on the lower doses of F-2 and T-2 toxins, the parasite infection ran a similar course to that in the control groups, and the animals became resistant to re-infection. However, when higher doses (2.0-6.0 mg kg-1) of T-2 toxin were used, a depression of weight gain was observed with some other physiological parameters (PCV, weight of bursa, weight of thymus, skin thickness in PHA-P skin test) also indicating toxic effect and, simultaneously, the oocyst output decreased significantly and the patent period was slightly prolonged. Although certain modifications of the immune response could be revealed, the chickens became resistant to re-infection. Only early (1 week of age) parasite infection and 6 mg kg-1 T-2 toxin in the feed significantly depressed body weight gain and immunity.

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

Detection of Cryptosporidium parvum DNA in formed human feces by a sensitive PCR-based assay including uracil-N-glycosylase inactivation.

We developed a PCR-based method that can be used to identify Cryptosporidium parvum in human feces. Fecal oocysts were concentrated by centrifugation on a sodium chloride gradient and filtration on a nitrocellulose filter prior to DNA extraction and PCR amplification of a 452-bp C. parvum-specific DNA sequence with a protocol including dUTP and uracil-N-glycosylase. All samples obtained from naturally infected humans (n = 10), calves (n = 4), and goats (n = 2) were positive. A 100% detection rate was achieved with both formed and solid stools (n = 10) seeded with 1,000 C. parvum oocysts per g. Procedures based on stool concentration by a modified Ritchie method and subsequent oocyst identification by immunofluorescent labeling or acid-fast staining require concentrations of 50,000 to 500,000 oocysts per g to achieve a 100% detection rate with formed stools. The described PCR-based assay thus has a 50- to 500-fold increase in sensitivity compared to those of the methods commonly used to analyze formed feces.

Animals↗
PubMed1997

Plasma dehydroepiandrosterone sulfate levels in patients with hyperfunctioning and non-hyperfunctioning adrenal tumors before and after adrenal surgery.

To investigate the clinical significance of plasma dehydroepiandrosterone sulfate (DHEAS) measurements, 175 patients with histologically confirmed adrenal tumors, 10 cortisol-producing adenomas, 59 aldosterone-producing adenomas, 56 non-hyperfunctioning adenomas, 13 adrenocortical carcinomas, 13 adrenal cysts, and 24 adrenomedullary tumors were studied. Plasma DHEAS levels were expressed as percentage of the mean of sex- and age-matched groups of healthy, normal subjects (DHEAS %). We found that before adrenal surgery, DHEAS % values were significantly reduced in patients with cortisol-producing (mean, 15.2% of control; 95% confidence interval (CI), 9.4-24.7%), non-hyperfunctioning (28.4%; 22.4-36.0%) as well as aldosterone-producing adrenocortical adenomas (55.4%; 47.1-65.1%) compared with controls, while values were normal in patients with adrenal cysts and in those with adrenomedullary tumors. Plasma DHEAS % values exhibited a great variability in adrenocortical carcinomas (mean, 84.0%; 95% CI, 33.2-212.5%). Death from adrenocortical carcinoma was more frequent in patients with high plasma DHEAS % values compared with those with low DHEAS %. During long-term postoperative monitoring, we found that plasma DHEAS levels of patients with aldosterone-producing and non-hyperfunctioning adenomas returned to normal in the second and fourth postoperative year respectively. In patients with cortisol-producing adenomas, plasma DHEAS remained suppressed for as long as 8 years after the operation. These findings show that except in adrenocortical carcinomas and cysts, plasma DHEAS levels are significantly decreased in all groups of adrenocortical tumors, including non-hyperfunctioning and aldosterone-producing tumors. The extent of this decrease and the postoperative persistence of suppressed plasma DHEAS levels may be related to the glucocorticoid production of adrenocortical tumors.

Adenoma↗
PubMed1997

Attempts to immunize chickens against Cryptosporidium baileyi with C. parvum oocysts and Paracox vaccine.

To study the possibility of immunization against Cryptosporidium baileyi Current, Upton et Haynes, 1986 with the attenuated anticoccidial vaccine, Paracox and oocysts of C. parvum Tyzzer, 1912, chickens were inoculated orally with either 3 x 10(3) vaccine oocysts or 8 x 10(5) C. baileyi or C. parvum oocysts at 1 week of age. The inoculation with Paracox vaccine and C. parvum oocysts was repeated at 2 and 3 weeks of age. Uninfected birds served as controls. All animals with the exception of one uninfected group were challenged orally with either 8 x 10(5) C. baileyi or 3 x 10(5) Eimeria tenella Railliet et Lucet, 1891 oocysts at 4 weeks of age. Sera were collected at 4 weeks of age, and were examined by ELISA using C. baileyi antigens. Birds inoculated with C. parvum oocysts did not shed C. parvum oocysts in their faeces, but anticryptosporidial antibodies could be detected in the sera. The total oocyst output of C. parvum inoculated chickens was 17% of that of previously uninfected birds after the oral challenge with C. baileyi. Considering that antibodies play no or only a minor role in resistance to C. baileyi, these results suggest that inoculation of chickens with C. parvum oocysts stimulated also cellular immune response. Based on the relative body weight gain, faecal scores, oocyst output, mortality, and caecal lesions in the birds immunized with Paracox vaccine and challenged with E. tenella, the vaccination induced only a moderate protection against the reinfection. The results of cross-immunization of chickens with Eimeria spp. and C. baileyi suggest that attenuated anti-eimerian vaccines do not induce any protection against cryptosporidial infection.

Animals↗
PubMed1996

The effects of post-translational side-chain modifications on the stimulatory activity, serum stability and conformation of synthetic peptides carrying T helper cell epitopes.

Peptides 31D and VF13, corresponding to the rabies virus nucleo- and glycoproteins, respectively, vigorously stimulate T helper cells of the appropriate specificity. Earlier we showed how internal and external glycosylation affects the major histocompatibility complex molecule (MHC)-binding ability and conformation of these T-cell epitopes (Otvos et al. (1994) Biochim. Biophys. Acta 1224, 68-76; Otvos et al. (1995) Biochim. Biophys. Acta 1267, 55-64). In the current report, we examined the T-helper cell stimulatory ability after introduction of a new set of post-translational modifications. To obtain general information concerning the effects of amino acid side-chain modifications on other biochemical properties of protein fragments, we studied the serum stability and the conformation of the 31D and VF13 peptides. We found that the extent of the reduction of the T-cell stimulatory activity depends upon the location in the sequence of the host amino acid residue. Generally, beta-linked sugars in mid-chain positions had a greater inhibitory effect than alpha-linked sugars attached to identical amino acids. In a case where mid-chain glycosylation just marginally reduced the T-cell stimulatory activity, the beta-linked glycopeptide was significantly more resistant to serum proteases. This finding suggests that addition of beta-linked carbohydrates might be superior to the addition of alpha-linked sugars for vaccine development, and generally for peptide agonist drug design. In addition, data presented here provide the first documentation that phosphorylation and sulfation of tyrosine residues may retain the MHC-binding ability and T-cell stimulatory activity of class II epitopes. The sulfated and the phosphorylated 31D peptides exhibited considerably increased serum stability compared to the unmodified parent peptide. Finally, all post-translational modifications destabilized the dominant alpha-helical or turn structures of the peptides presented in aqueous trifluoroethanol mixtures. While the circular dichroism spectra of the alpha- and beta-linked VF13 glycopeptides with monosaccharides were almost indistinguishable, the structure of the glycopeptides depended upon the length of the sugar moiety. Significantly, incorporation of sulfate or phosphate groups resulted in identical peptide conformations.

Amino Acid Sequence↗
PubMed1996

[Endocrinologic complications of neurofibromatosis type 1].

Neurofibromatosis type 1 is the most common autosomal dominant inheritable disease, which is often associated with secondary forms of hypertension and with tumors of neuroectodermal origin. The authors present the results of evaluation of 60 members of 3 families. Of the 60 family members, 13 subjects had symptoms of neurofibromatosis type 1 disease, of which 7 subjects were evaluated. The case histories of patients are discussed: (1) An incidentally discovered adrenal tumor was proved to be a pheochromocytoma. (2) Because of complaints similar to thyrotoxicosis, thyrostatic drugs were administered for years without effect and, finally, an adrenal phaeochromocytoma was diagnosed after the presence of neurofibromatosis was established. (3) Preeclamptic pregnancy of a young primigravida complicated with severe HELLP syndrome (hemolysis-elevated liver enzymes-low platelet count) led to thorough evaluation which revealed renal artery stenosis. In this patient, percutaneous renal artery angioplasty resulted in a complete cessation of hypertension. (4) Glucocortocoid replacement therapy in a patient with neurofibromatosis type 1 resulted in a complete normalization of both secondary adrenal insufficiency and a previously unexplained iron-refractor iron-deficient anemia. The case histories of the patients demonstrate a lack of in-depth knowledge of neurofibromatosis in clinical practice. A regular follow-up of neurofibromatosis patients is suggested in specialized health centers.

Adrenal Gland Neoplasms↗
PubMed1996

Effects of bursectomy and thymectomy on the development of resistance to Cryptosporidium baileyi in chickens.

Comparisons were made between the course of infection with Cryptosporidium baileyi in normal chickens and in chickens with functional deficiencies in either B-lymphocytes (bursectomized) or T-lymphocytes (thymectomized). Bursectomy did not influence the acquired immune response to C. baileyi infection as measured by the oocyst excretion. However, the total oocyst output of bursectomized birds was less than a quarter of that of the controls due to the reduced site for multiplication of the parasite. The total oocyst output of thymectomized chickens was more than 2 times higher and the patency was 2 times longer as compared with control animals. Moreover, thymectomized birds failed to acquire resistance to the challenge infection. These findings attest to the primary role of cell-mediated immunity in the expression of resistance to C. baileyi as opposed to the antibody-mediated mechanisms.

Animals↗
PubMed1996

Poly (DL-lactide-co-glycolide) microspheres as carriers for peptide vaccines.

Peptides carrying an immunodominant T-helper cell epitope delineated from the rabies virus nucleoprotein either alone or in combination with a linear B-cell epitope from the same protein were incorporated into three different formulations of poly(DL-lactide-co-glycolide) (PLG) which were distinct in their composition, and consequently in their peptide release rates. In vitro peptides incorporated into any of the PLG formulations stimulated a peptide-specific T-cell line. Upon subcutaneous immunization of mice, the PLG formulation that showed the fastest peptide release rate induced the best immune response. This immune response was in magnitude comparable or even superior to that induced by peptide emulsified in complete Freund's adjuvant.

Amino Acid Sequence↗
PubMed1996

Attempts to immunize chickens with Cryptosporidium baileyi oocyst extract.

In order to study the possibility of immunization against Cryptosporidium baileyi with extracted crude antigen, Arbor Acres chickens were injected intramuscularly with 80 micrograms of C. baileyi oocyst-derived proteins (uninfected immunized, UI) or inoculated orally with 8 x 10(5) viable C. baileyi oocysts (infected control, IC) at 1 wk of age. The immunization was repeated in the UI group at 2 wk of age. Uninfected (UC) birds served as controls. All animals in UI, IC, and UC groups were challenged orally with 8 x 10(5) C. baileyi oocysts at the age of 4 wk. Blood samples were collected when birds were 4 and 6 wk of age, and sera were examined by enzyme-linked immunosorbent assay for the presence of antibodies against C. baileyi. Total oocyst output of UI chickens was about 60% of that of UC birds after challenge, and the prepatent and patent periods were nearly identical in the latter 2 groups. In contrast, IC birds developed complete resistance to challenge infections. These results suggest that immunization with the oocyst extract of C. baileyi may confer some degree of protection against oral challenge; however, the protection is less effective than that induced by primary oral infection. The lack of significant difference between the antibody responses of IC and UI animals to C. baileyi at 2 wk of age suggests that serum antibodies play little role in acquired resistance to challenge infection.

Animals↗
PubMed1996

Efficacy of a monensin-duokvin combination against Eimeria acervulina in chickens.

Anticoccidial efficacy of a drug combination monensin at 8 p.p.m. plus the new antioxidant duokvin at 120 p.p.m. in the feed was compared with that of monensin alone at the recommended level of 100 p.p.m. against a field isolate of the coccidium Eimeria acervulina Tyzzer, 1929 in a battery study. Both monensin and monensin duokvin combination were effective against E. acervulina when judged by weight gain, feed conversion and faecal scores. There was no significant difference in the chemoprophylactic activity of either treatments. Neither monensin at 100 p.p.m. nor the combination proved effective in terms of oocyst production. In accordance with the earlier findings with E. tenella, the combination seems appropriate for field trials.

Animals↗
PubMed1996

Remodelling of septal branch of coronary artery and carotid artery in L-NAME treated rats.

Coronary and carotid artery structure was studied in rats in order to analyze the processes in the cardiovascular system in NO-deficient hypertension model. Long-term inhibition of NO synthase was induced by L-nitro arginine methyl ester (L-NAME, 50 mg/kg/day p.o.) for a period of 8 weeks. An increase in blood pressure and heart/body weight ratio confirmed the reliability of the model. The wall thickness as well as the calculated wall area of the coronary artery increased by 70% and 50%, respectively, in comparison to control vessels. The wall thickness and the calculated wall area of the carotid artery increased by 73% and 70%, respectively. Further analysis indicated that both the tunica intima and tunica media in the coronary and the carotid artery increased quantitatively in a similar manner. Remarkable differences were found in the contribution of cellular and noncellular components in the tunica media of the coronary and carotid arteries of experimental animals. The calculated extracellular area increased by 116% in comparison to the control coronary artery and by 97% in comparison to the control carotid artery. The increase in extracellular matrix of the tunica media of coronary and carotid arteries seems to be basic cause of the remodelling of the vessels studied.

Animals↗
PubMed1995

Quantitative method to assess Cryptosporidium oocyst shedding in the chicken model.

An unsophisticated and fairly sensitive quantitative method and its grounds are described, which proved useful to assess Cryptosporidium oocyst shedding in the chicken model. The method is based on the rather slow sedimentation of oocysts. A threshold of sensitivity ranging between 5,000 and 10,000 oocysts/g feces was established for this technique. There was good agreement between triplicate assays over a wide range of oocyst concentrations.

Animals↗