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Biomedical subjects

A Tóth

Publications and source records attributed to A Tóth.

At least 37 records · Page 2Linked to original sources
PubMed2001

Renal injury in perinatal hypoxia: ultrasonography and changes in renal function.

UNLABELLED: We studied 12 hypoxaemic neonates (5 mature newborns, birth weight 2850-4200 g, gestational age 37-41 weeks; and 7 premature newborns, birth weight 770-1850 g, gestational age 27-34 weeks;) with repeated urine and blood chemistry on the 1st and 3rd days of life. Nephrosonographical examinations on the 1st, 3rd and 5-7th days of life were also performed. As controls, 12 healthy infants were examined (gestational age 36-42 weeks; birth weight 24504200 g). Hypoxic neonates had higher serum creatinine and blood urea nitrogen levels. Tubular markers also demonstrated renal tubular damage. Neonates in both hypoxic groups were hyperuricaemic and hyperuricosuric, and had higher urinary protein concentrations. All these infants exhibited an increased echogenicity of the renal cortex, and 11/12 showed the same finding in the medullary area. These findings disappeared within 1 week in all infants. Among the 12 healthy control infants, no cortical hyperechogenicity was found and only three of these infants displayed transient medullary renal hyperechogenicity. CONCLUSION: Since the hypoxaemic infants demonstrated greatly increased urinary concentrations of uric acid and protein, we suggest that a temporary precipitation of these two agents may be responsible for the ultrasonographic findings. Circulatory redistribution might play a role in the phenomenon of cortical hyperechogenicity.

Blood Urea Nitrogen↗
PubMed2001

Fluorescence in situ hybridization of chorionic interphase cells for prenatal screening of Down syndrome.

OBJECTIVE: Our purpose was to determine the usefulness and reliability of fluorescence in situ hybridization on interphase chorionic villi cells in the prenatal diagnosis of Down syndrome. METHODS: A total of 336 samples of chorionic villi were analysed by direct chromosome preparation and FISH with a DNA probe specific to chromosome 21. The samples were obtained as part of the routine obstetric investigation and management. RESULTS: The sampling and direct karyotyping was successful in all cases. At least 50 cells were valuable by FISH in 331 of 336 samples. Both methods showed Down syndrome in 12 cases. The follow-up investigations showed that there was no false-negative or false-positive result following these procedures. CONCLUSION: Based on these results and the fact that it is possible to analyse by interphase FISH at least ten times more cells than by conventional cytogenetic methods, and these cells originate from different tissues of chorionic villi, it is concluded that FISH increases the reliability of the diagnosis. Nevertheless, more data are needed for correct statistical analysis. Since this method is cheaper and gives diagnosis earlier than cell culture, the combination of direct chromosome preparation and FISH on chorionic villi is offered for prenatal Down syndrome screening.

Chorionic Villi↗
PubMed2001

Concomitant accumulation of intracellular free calcium and arachidonic acid in the ischemic-reperfused rat heart.

This study was designed to elucidate the relationship between enhanced cytoplasmic calcium levels (Ca2+i) and membrane phospholipid degradation, a key step in the loss of cellular integrity during cardiac ischemia/reperfusion-induced damage. Isolated rat hearts were subjected to 15 min ischemia followed by 30 min reperfusion. Ca2+i was estimated by the Indo-1 fluorescence ratio technique. Degradation of membrane phospholipids as indicated by the increase of tissue arachidonic acid content was assessed in tissue samples taken from the myocardium at various points of the ischemia/reperfusion period. The hemodynamic parameters showed almost complete recovery during reperfusion. Fluorescence ratio increased significantly during ischemia, but showed a considerable heart-to-heart variation during reperfusion. Based upon the type of change of fluorescence ratio during reperfusion, the hearts were allotted to two separate subgroups. Normalization of fluorescence ratio was associated with low post-ischemic arachidonic acid levels. In contrast, elevated fluorescence ratio coincided with enhanced arachidonic acid levels. This observation is suggestive for a relationship between the Ca2+-related fluorescence ratio and arachidonic acid accumulation probably due to a calcium-mediated stimulation of phospholipase A2.

Animals↗
PubMed2000

[Investigation of the cerebral projection of the vestibular system using positron emission tomography].

The authors investigated the cerebral projection of the vestibular system, using positron emission tomography, in right-handed subjects. Both sided cold caloric stimulation was used in every volunteer (n = 6). A detailed map of activated and deactivated brain regions is included. This portrays changes caused by vestibular stimulation. The contralaterally activated regions according to the stimulation side were: postcentral gyrus, transvers temporal gyrus, superior temporal gyrus, posterior part of the insula, claustrum, putamen, inferior parietal lobule, precentral gyrus, premotor cortex, cingulate gyrus. The ipsilaterally activated regions were: transvers temporal gyrus, superior temporal gyrus, inferior parietal lobule, posterior part of the insula. There was no hemispherial dominance. The activated regions partially correspond with previous results in the literature. It would like to be pointed out the Brodmann 6 region as the cortical manifestation of involuntary isometric tightening of muscles. The contralaterally deactivated regions were: inferior, superior and medius temporal gyrus, medial and medius frontal gyrus, inferior occipital gyrus, parahippocampal gyrus and hippocampus. Ipsilaterally deactivated regions were: superior and medial frontal gyrus, inferior temporal gyrus, angular gyrus, parahippocampal gyrus and hippocampus, fusiform and inferior occipital gyrus. There was prominent hemispherial dominance in the stimulated, ipsilateral side. The deactivation based functional connection between the hippocampus and the vestibular system was pointed out in such a relation for the first time in this report.

Adult↗
PubMed2000

Functional genomics identifies monopolin: a kinetochore protein required for segregation of homologs during meiosis i.

The orderly reduction in chromosome number that occurs during meiosis depends on two aspects of chromosome behavior specific to the first meiotic division. These are the retention of cohesion between sister centromeres and their attachment to microtubules that extend to the same pole (monopolar attachment). By deleting genes that are upregulated during meiosis, we identified in Saccharomyces cerevisiae a kinetochore associated protein, Mam1 (Monopolin), which is essential for monopolar attachment. We also show that the meiosis-specific cohesin, Rec8, is essential for maintaining cohesion between sister centromeres but not for monopolar attachment. We conclude that monopolar attachment during meiosis I requires at least one meiosis-specific protein and is independent of the process that protects sister centromere cohesion.

Anaphase↗
PubMed2000

[Familial occurrence of Turner syndrome].

The authors report a family in which a woman with the mosaic Turner karyotype 45,X/46,X,r(X) transmitted the ring (X) chromosome to the second daughter and transmitted the X-derived chromosome to the first daughter. The mother had normal fertility with three documented pregnancies and conceptions occurred without any hormonal therapy. Her first pregnancy ended with spontaneous abortion, while the second pregnancy resulted in a 45,X/46,X,+mar female with ovarian failure and the third pregnancy resulted in a 45,X/46,X,r(X) female. The nature of the ring chromosome was confirmed by conventional cytogenetic technics. A small marker chromosome was identified as an X-derived chromosome by fluorescent in situ hibridisation (FISH).

Adolescent↗
PubMed2000

Phosphorylation of MYPT1 by protein kinase C attenuates interaction with PP1 catalytic subunit and the 20 kDa light chain of myosin.

The effect of phosphorylation in the N-terminal region of myosin phosphatase target subunit 1 (MYPT1) on the interactions with protein phosphatase 1 catalytic subunit (PP1c) and with phosphorylated 20 kDa myosin light chain (P-MLC20) was studied. Protein kinase C (PKC) phosphorylated threonine-34 (1 mol/mol), the residue preceding the consensus PP1c-binding motif ((35)KVKF(38)) in MYPT1(1-38), but this did not affect binding of the peptide to PP1c. PKC incorporated 2 mol P(i) into MYPT1(1-296) suggesting a second site of phosphorylation within the ankyrin repeats (residues 40-296). This phosphorylation diminished the stimulatory effect of MYPT1(1-296) on the P-MLC20 phosphatase activity of PP1c. Binding of PP1c or P-MLC20 to phosphorylated MYPT1(1-296) was also attenuated. It is concluded that phosphorylation of MYPT1 by PKC may therefore result in altered dephosphorylation of myosin.

Animals↗
PubMed2000

[Ethical aspects of prenatal screening for Down's syndrome].

Trisomy 21, the chromosomal base of Down's syndrome, results in severe mental and physical handicap. Owing to the development of medical genetics reliable screening and diagnostic procedures for the detection of the disorder are available in Hungary. To achieve the goals of prenatal screening it is important to address the main ethical issues arising through the application of technical-professional skills. The core objective of prenatal screening for Down's syndrome is to give information about the genetic condition of the fetus in order to enhance the autonomy of the parents in family planning. Screening programs should respect the ethical requirements of the principles of "do no harm", beneficence and autonomy of the patients, which are the most important ethical norms of doctor-patient relationship. Regarding the social aspects of screening it is essential to claim that voluntary participation and nondirective genetic counselling can exclude eugenic purposes. Though introduction of prenatal tests does not imply the discrimination of the disabled, anxiety of handicapped people deserves more attention. Abortion of affected fetuses isn't among the objectives of prenatal genetic screening but patient's autonomy is supported in decisions concerning the future of the pregnancy. Social justice can be taken into consideration by providing the test to all women without respect to their social position, educational level or their age. An open debate about the issues of prenatal screening for Down's syndrome could promote the formation of a consensus between professionals and the public.

Abortion, Therapeutic↗
PubMed2000

Prediction of early renal graft function by the measurement of donor urinary glutathione S-transferases.

BACKGROUND: We have investigated the possibility of urinary alpha- and pi class glutathione S-transferases (GST-a; GST-pi) serving as a valuable parameter to predict early graft function after transplantation. METHOD: Urinary GST concentrations of 61 donors (DON) and recipients (REC) were analyzed at preoperative, intraoperative, and postoperative periods. We grouped recipients according to the early postoperative graft recovery days. RESULTS: The donor graft function, represented by the donor urinary GST concentration (GST-pi:17,1+/-12 microg/l mmol creatinine (crea); GST-a:14,3+/-10 microg/mmol crea), sustained a loss in comparison to the healthy controls (GST-a; pi< or =1 microg/mmol crea). According to statistical analysis, the donor GST-pi level showed a strong correlation with graft recovery days-pi (r = 0.84; P<0.001). The early graft function cannot be predicted by means of cold ischemia time (22.8+/-3.4 hr), nor handling time (42.4+/-11.1 min), nor even the intraoperative enzyme concentrations. The GST-pi cut off level (12.55 microg/mmol crea) might predict the possible posttransplant graft dysfunction. The discriminative analysis showed that using only DON GST-pi alone could discriminate well between the groups among all grafts in 68%. CONCLUSION: Prognosis is poorer if the donor GST-pi concentration is above 12.55 microg/mmol crea. On the basis of the determination of GST-pi concentration in the donor urine, we can predict graft viability before the surgical procedure with a reliability of 68%.

Adult↗
PubMed2000

Synthesis of the repeating unit of the O-specific polysaccharide of Shigella sonnei and quantitation of its serologic activity.

The chemical synthesis of the zwitterionic disaccharide 2 is described that corresponds to the repeating unit of the O-specific polysaccharide (1) of the gram-negative human pathogen Shigella sonnei. Passive hemolysis inhibition tests using a hyperimmune rabbit serum raised against S. sonnei showed that the serologic activity of the disaccharide 2 is nearly 2- to 3-fold higher than those of its component monosaccharides. NMR data of 2 are in support of the proposed structure of the O-specific polysaccharide.

Animals↗
PubMed2000

Preliminary communication: examination of the harmful effect to fetuses of fumonisin B(1) in pregnant sows.

Three sows were fed a diet mixed with Fusarium moniliforme fungal culture from the 107th day of pregnancy until parturition. Fumonisin B(1) toxin was administered to two sows (sows 1 and 2) in a daily dose of 300 mg for an additional 7 days subsequent to parturition, i.e., for a total of 14-16 days. The third sow (No. 3) was given the toxin in the same daily dose only until parturition, i.e., for 7 days in total. There were no symptoms observed in any of the sows. Two piglets were taken from each of the three sows and sacrificed immediately after parturition, i.e., prior to the first suckling. After 24 h, two additional piglets were taken for slaughter from each of the litters, which by then had access to colostrum. Finally, on the 7th day postparturition another two piglets per litter were sacrificed and material obtained from them was processed for examination. It was established that fumonisin B(1) present in the Fusarium moniliforme culture resulted in damage to the fetuses in utero. Of the changes indicating toxic effect, intraalveolar, subpleural, and interstitial pulmonary edema of various degrees of severity could be detected in the piglets sacrificed immediately following parturition and before the first suckling. Pathological changes were observed in the histopathological sections of the liver, and increases in the activities of plasma aspartic acid transaminase (AST), gamma glutamyl transferase (GGT) and alkaline phosphatase (AKLP), higher than physiological levels were detected. The serum-free sphinganine/sphingosine ratio, considered a bioindicator of fumonisin B(1) toxicosis, varied in accordance with the degree of severity of the changes which occurred. The values obtained were found to be between 0.29 and 0.36 in the cases of severe pulmonary edema, and between 0.20 and 0.24 for the cases of mild pulmonary edema. In the piglets of the sows fed the toxin for an additional 7 days subsequent to parturition and which were born with severe pulmonary edema, mild pulmonary edema could be detected after colostrum suckling, 24 h, and 7 days after parturition. The SA/SO value of the serum in these two piglets was 0.19 and 0.20, while at the same time AST, GGT, and ALKP values higher than physiological levels were measured. In the milk samples taken from sows 1 and 2 and examined after 24 h and after 7 days FB(1) was detected in quantities of 18.0-27.5 ppb. There were no changes observed on the seventh day in the piglets of the third sow, the diet of which contained no toxin after parturition. However, as the piglets of the third sow demonstrated only mild effects of pulmonary edema it is not possible to establish with certainty a postpartum cause-effect relationship between fumonisin in colostrum and pulmonary edema.

Aging↗
PubMed2000

Ischemia/reperfusion-induced changes in intracellular free Ca2+ levels in rat skeletal muscle fibers--an in vivo study.

Accumulation of intracellular free calcium (Ca2+i) may play an essential role in the ischemia/reperfusion injury of skeletal muscle. Although it has been shown that Ca2+i levels significantly increase during ischemia/reperfusion, it is still a matter of debate whether Ca2+i increases during ischemia alone. It was the aim of this study to monitor the in vivo Ca2+i levels in the rat spinotrapezius muscle during ischemia of varying duration and reperfusion, using a ratiometric fluorescence technique, and to investigate the relationship between the postischemic flow patterns and Ca2+i, if any. The muscle was loaded with Indo-1/AM and imaged by a cooled digital camera. Pre- and postischemic tissue perfusion was assessed by means of an analogue camera. Our results show that short-term ischemia (5, 15 and 30 min) and subsequent reperfusion (60 min) does not alter Ca2+i homeostasis and that tissue perfusion promptly recovers after the insult. One or two hours of ischemia resulted in changes in Ca2+i levels, varying from preparation to preparation; increases in some and no changes in others. In these preparations three distinct flow patterns - normal, compromised and no-reflow - could be distinguished during the 60-min reperfusion. Our main conclusion is that in skeletal muscle Ca2+i levels may increase, the increase probably depending on the muscle fiber type exposed.

Animals↗
PubMed2000

Study of the subunit interactions in myosin phosphatase by surface plasmon resonance.

The interactions of the catalytic subunit of type 1 protein phosphatase (PP1c) and the N-terminal half (residues 1-511) of myosin phosphatase target subunit 1 (MYPT1) were studied. Biotinylated MYPT1 derivatives were immobilized on streptavidin-biosensor chips, and binding parameters with PP1c were determined by surface plasmon resonance (SPR). The affinity of binding of PP1c was: MYPT11-296 > MYPT11-38 > MYPT123-38. No binding was detected with MYPT11-34, suggesting a critical role for residues 35-38, i.e. the PP1c binding motif. Binding of residues 1-22 was inferred from: a higher affinity binding to PP1c for MYPT11-38 compared to MYPT123-38, as deduced from SPR kinetic data and ligand competition assays; and an activation of the myosin light chain phosphatase activity of PP1c by MYPT11-38, but not by MYPT123-38. Residues 40-296 (ankyrin repeats) in MYPT11-296 inhibited the phosphorylase phosphatase activity of PP1c (IC50 = 0.2 nM), whereas MYPT11-38, MYPT123-38 or MYPT11-34 were without effect. MYPT140-511, which alone did not bind to PP1c, showed facilitated binding to the complexes of PP1c-MYPT11-38 and PP1c-MYPT123-38. The inhibitory effect of MYPT140-511 on the phosphorylase phosphatase activity of PP1c also was increased in the presence of MYPT11-38. The binding of MYPT1304-511 to complexes of PP1c and MYPT11-38, or MYPT11-296, was detected by SPR. These results suggest that within the N-terminal half of MYPT1 there are at least four binding sites for PP1c. The essential interaction is with the PP1c-binding motif and the other interactions are facilitated in an ordered and cooperative manner.

Amino Acid Sequence↗
PubMed2000

Experiment to determine limits of tolerance for fumonisin B1 in weaned piglets.

In Hungary almost 70% of mould-affected maize inspected since 1993 was found to be contaminated with fumonisin B1 (FB1) (mean 2.6-8.65 mg/kg; maximum 9.8-75.1 mg/kg), the degree of this contamination was found to increase from year to year (Fazekas et al., 1997b). In this experiment, in order to define tolerance limit values, the effect of exposing weaned piglets to FB1 in low doses over a 4-week period was examined. The experiment was performed with 20 weaned barrows of Danish Landrace breed. After a 5-day adaptation period cultures of the fungus Fusarium moniliforme were mixed into the animals' feed in concentrations that resulted in a daily intake of fumonisin B1 of 0, 10, 20 and 40 mg/kg feed. Feeding with the toxin was observed to exert no significant effect on body weight gain or feed consumption in the animals, no clinical signs were observed and no mortality traceable to toxic effects occurred. In computer tomography examinations performed in the second and fourth weeks mild and more severe pulmonary oedema was diagnosed in the experimental animals. The processes developing in the pulmonary parenchyma were corroborated by the mathematical and statistical evaluation procedures applied. The haematological parameters examined revealed no change attributable to toxic effects, while with respect to the biochemical parameters, an increase in aspartate aminotransferase (AST) activity dependent on dosage, indicating a pathological change in the liver, was ascertained in all three experimental groups. The free sphinganine to sphingosine ratio (SA/SO), which is regarded as the most sensitive bioindicator of fumonisin toxicosis, showed an increase proportionate to toxin concentration for all three dosages. Dissection revealed mild cases of pulmonary oedema in three of the animals given doses of 10 p.p.m. (n = 4), two mild and two severe cases in those exposed to 20 p.p.m. (n = 5), and severe cases in all five animals given 40 p.p.m. The oedema of non-inflammatory origin was confirmed by histopathological examinations. The findings of this experiment which indicate that in this study FB1 administered in substantially lower concentrations than those reported in the literature resulted in severe pathological changes, point to the importance of studies involving even lower doses.

Animal Feed↗
PubMed2000

Effect of osmolarity on aldosterone production by rat adrenal glomerulosa cells.

The effect of osmotic changes on aldosterone production, [Ca2+]i and voltage-gated Ca2+ currents, was studied in cultured rat glomerulosa cells. Alteration of osmolarity by sucrose addition in the 250-330 mosM range did not influence aldosterone production per se, but it substantially affected K+-stimulated aldosterone production. Hyposmosis markedly increased the hormone response evoked by raising [K+] from 3.6 to 5 mM, whereas hyperosmosis had a mild decreasing effect. Cytoplasmic [Ca2+]i, measured in single glomerulosa cells, did not show detectable change in response to either hyposmotic or hyperosmotic exposure, but the [Ca2+]i signal evoked by elevation of [K+] to 5 mM was augmented in hyposmotic solution. The osmosensitivity of the transient (T)-type and long-lasting (L)-type voltage-gated Ca2+ currents was studied using the nystatin-perforated voltage-clamp technique. Lowering osmolarity to 250 mosM significantly increased the amplitude of the T-type current, and it had a transient augmenting effect on L-type current amplitude. Hyperosmotic solution (330 mosM) reduced L-type current amplitude but did not evoke significant change in T-type current. These results indicate that the responsiveness of rat glomerulosa cells to physiological elevation of [K+] is remarkably influenced by changes in osmolarity by means of modulating the function of voltage-gated Ca2+ channels.

Aldosterone↗
PubMed2000

Effect of beta-carotene and nucleotide base supplementation on blood composition and immune response in weaned pigs.

The effect of synthetic beta-carotene and synthetic nucleotide base on daily weight gain, feed consumption and certain haematological, biochemical and immunological parameters of piglets were studied in a 3-week experiment. Beginning one week prior to weaning, the diet fed to one experimental group of piglets was supplemented with 10% Rovimix Beta-carotene at 875 mg/kg of diet. Synthetic uracil and adenine (98%, Sigma-Aldrich) were mixed into the diet of the other experimental group at doses of 500 mg/kg of diet for each substance. The control group received the basic diet without any supplementation. The changes observed over time in the haematological parameters and in certain biochemical variables could be regarded as physiological. By day 21 of the experiment, beta-carotene supplementation had significantly lowered the neutrophilic granulocyte percentage and elevated the lymphocyte percentage, while in the other two groups a change of opposite tendency occurred. At the end of the experimental period there was a decrease in plasma vitamin E concentration due to carotene supplementation (control: 6.1 +/- 1.5, nucleotide: 6.3 +/- 2.5, carotene: 2.3 +/- 1.5 mg/L). Lymphocyte blastogenesis induced by phytohaemagglutinin and concanavalin A increased by 50 and 130%, respectively, in the nucleotide group and by 60 and 30%, respectively, in the carotene group, while it did not change in the control group. The supplements exerted no positive effect on the in vivo cellular immune response.

Adenine↗