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Biomedical subjects

L Szabo

Publications and source records attributed to L Szabo.

At least 19 recordsLinked to original sources
PubMed2006

In vitro microspore selection in maize anther culture with oxidative-stress stimulators.

In order to produce doubled-haploid maize plants tolerant of oxidative stress, in vitro microspore selection was carried out in anther culture with reactive oxygen species (ROS) progenitors such as paraquat, menadione, tert-butylhydroperoxide (t-BHP), and methionine combined with riboflavin. All the ROS progenitors reduced the anther induction, the formation of microspore-derived structures, and their regeneration potential. Abnormal cell divisions and progeny cell degradation could be observed during the development of microspores treated with ROS progenitors. Menadione and t-BHP influenced the microspore developmental pathway, as menadione induced the formation of embryoids, while t-BHP increased the proportion of calli in the microspore-derived structures. As the result of in vitro selection, 15, 10, 10, and 3 fertile doubled-haploid plants were obtained in cultures treated with paraquat, t-BHP, methionine combined with riboflavin, and menadione, respectively.

Cell Survival↗
PubMed2004

[Results of laparoscopic repair of abdominal wall hernias using an ePTFE-polypropylene composite mesh].

BACKGROUND: The standard technique for laparoscopic ventral hernioplasty (peritoneal onlay) reduces the recurrence rate and the rate of other complications, in particular the risk of infections. However, the procedure requires a special mesh to mitigate the risk of visceral adhesions. For this purpose an ePTFE mesh is generally used. There are limited reported clinical data regarding the long-term results and benefits of other biomaterials. STUDY DESIGN: Bard Composix mesh was used for laparoscopic ventral hernia repair. This biomaterial combines two different clinically proven materials--polypropylene with a thin layer of ePTFE--to maximize ingrowth of surrounding tissue, while mitigating the risk of visceral adhesions. Demographic, operative and postoperative data were collected and analyzed. Follow-up clinical evaluations were conducted 6-10 days, 4 weeks, and every 6 (th) month after surgery in all patients. RESULTS: Fifteen patients were involved in the study. The mean operating time was 101.2 min (64-190 min). There were no intraoperative complications or conversion to open procedure. Postoperative complications were 1 seroma, 4 cases of prolonged ileus, one tacks-site pain requiring second-look laparoscopy. Hospital discharge occurred on average 6 days (3-10 days) after surgery. The mean follow-up was 12.4 months (range 5-29 months). No late complications or hernia recurrence were observed. CONCLUSIONS: Laparoscopic prosthetic ventral hernioplasty using the composite polypropylene/ePTFE mesh offers short hospital stay and acceptable complications for primary and recurrent ventral hernias. Disadvantage of the composite mesh is the difficulty to roll this product into a sufficiently small size to permit its easy introduction into the abdominal cavity.

Adult↗
PubMed2001

Structure of a family 15 carbohydrate-binding module in complex with xylopentaose. Evidence that xylan binds in an approximate 3-fold helical conformation.

The recycling of photosynthetically fixed carbon by the action of microbial glycoside hydrolases is a key biological process. The consortium of degradative enzymes involved in this process frequently display catalytic modules appended to one or more noncatalytic carbohydrate-binding modules (CBMs). CBMs play a central role in the optimization of the catalytic activity of plant cell wall hydrolases through their binding to specific plant structural polysaccharides. Despite their pivotal role in the biodegradation of plant biomass, the mechanism by which these proteins recognize their target ligands is unclear. This report describes the structure of a xylan-binding CBM (CBM15) in complex with its ligand. This module, derived from Pseudomonas cellulosa xylanase Xyn10C, binds to both soluble xylan and xylooligosaccharides. The three-dimensional crystal structure of CBM15 bound to xylopentaose has been solved by x-ray crystallography to a resolution of 1.6 A. The protein displays a similar beta-jelly roll fold to that observed in many other families of binding-modules. A groove, 20-25 A in length, on the concave surface of one of the beta-sheets presents two tryptophan residues, the faces of which are orientated at approximately 240 degrees to one another. These form-stacking interactions with the n and n+2 sugars of xylopentaose complementing the approximate 3-fold helical structure of this ligand in the binding cleft of CBM15. In four of the five observed binding subsites, the 2' and 3' hydroxyls of the bound ligand are solvent-exposed, providing an explanation for the capacity of this xylan-binding CBM to accommodate the highly decorated xylans found in the plant cell wall.

Binding Sites↗
PubMed2001

Tryptophan hydroxylase gene polymorphism (A218C) and idiopathic recurrent miscarriage.

OBJECTIVE: To investigate the frequency of a polymorphism in intron 7 of the tryptophan hydroxylase gene among women with idiopathic recurrent miscarriage and healthy controls. METHODS: In a case control study, we studied 125 women with a history of three or more consecutive pregnancy losses before 20 weeks' gestation and 137 healthy controls with at least two live births and no history of pregnancy loss. Peripheral venous puncture, DNA extraction, and polymerase chain reaction followed by restriction fragment length polymorphism analysis were used to genotype women for the presence of the A218C polymorphism in intron 7 of the tryptophan hydroxylase gene. RESULTS: Allele frequencies among women with idiopathic recurrent miscarriage and controls were 32.4% and 38.7%, respectively, for allele A (wild type) and 67.6% and 61.3%, respectively, for allele C (mutant). No association between the presence of allele C and idiopathic recurrent miscarriage was found (P = .3; odds ratio 1.31; 95% confidence interval 0.93, 1.87). Genotype frequencies also were not significantly different between the study group (C/C: 44.8%; A/C: 45.6%; A/A: 9.6%) and the control group (C/C: 37.2%; A/C: 48.2%; A/A: 14.6%; P = .2). Between women with primary and women with secondary idiopathic recurrent miscarriage, no statistically significant differences with respect to allele frequencies were observed (63% vs 62% for allele C and 31% vs 38% for allele A; P = .3). CONCLUSION: The A218C polymorphism in intron 7 of the tryptophan hydroxylase gene is not associated with idiopathic recurrent miscarriage.

Abortion, Habitual↗
PubMed2001

[Acute pancreatitis after kidney transplantation].

UNLABELLED: Pancreatitis following kidney transplantation was first described by Starzl in 1964 [19]. The incidence rate of the disease involving severe complications ranges from 1.2 to 6.8%. The number of risk factors, besides those of the normal population, is increased by a number of other factors, i.e. uremia, disorder of lipid metabolism, polycystic kidney, immunosuppressive drugs, cytomegalovirus infection, etc. The mortality of acute pancreatitis in a kidney transplant patient is, in spite of treatment with the most up-to-date methods, is much higher (53-60%) than that for a non-transplant patient. In the period between 27 June 1991 and 31 December 2000 the number of cadaver kidney transplants performed in the Transplantation Division of the 1st Department of Surgery of the Medical and Health-Science Centre of the University of Debrecen was 349. During this period 9 incidences of acute pancreatitis were found in 8 patients. The frequency of incidence was 2.56%. In the present communication we analyse the prognosis of 9 kidney transplant patients, with special respect to immunosuppression. RISK FACTORS: One patient was administered Cyclosporin alone, four were given Cyclosporin and Steroids, a further one Cyclosporin, Steroids and Azathioprine, the remaining three were treated with Cyclosporin, steroids and Mycophenolate Mophetil. In six cases out of nine multiorgan insufficiency (kidney, lung, liver) was encountered on presentation, three cases were accompanied by peritonitis. In spite of early jejunal nutrition, intensive therapy, antibiotic treatment, CT monitoring, if needed, necrectomy and oncotomy, three of our patients died from multiorgan insufficiency induced by septico-toxic state (mortality 33.3%). Other six patients recovered. CONCLUSIONS: The mortality rate of acute pancreatitis is much higher in immunosuppressed patients. The role of the etiological factors is not unequivocal in the development of pancreatitis. Nevertheless, all possible risk factors have to be taken into consideration when starting the immunosuppressive treatment of transplant patients and during their follow-up. By optimally adjusting the immunosuppressants we can decrease the risk of pancreatitis, however, the prognosis of the diseases, in agreement with the data in the literature, cannot be considerably improved even with the most up-to-date methods.

Acute Disease↗
PubMed1999

Prognostic significance of mutations in the p53 gene, particularly in the zinc-binding domains, in lymph node- and steroid receptor positive breast cancer patients. Austrian Breast Cancer Study Group.

The aim of our study was to evaluate if p53 mutations, especially those in the L2/L3 domains of the p53 gene, add prognostic information for node-positive and steroid receptor positive breast cancer patients. Two hundred and five tumour samples from a randomised clinical trial of 596 lymph node- and steroid receptor positive breast cancer patients were included. All patients had been randomly allocated to receive 20 mg of adjuvant tamoxifen (TAM) daily for 2 years or TAM plus one cycle of low-dose, short-term chemotherapy. For detection of p53 mutations we used in vitro amplification by polymerase chain reaction and consecutively performed temperature gradient gel electrophoresis (PCR-TGGE) and direct sequencing. We found p53 mutations in 42/205 (20%) cases: 16/42 (38%) p53 mutations occurred within the L2/L3 domains of the p53 gene, and 26/42 (62%) outside the L2/L3 domains. p53 mutation served as a statistically significant parameter in predicting disease-free survival in univariate (P = 0.02) and multivariate (P = 0.009) analysis. For overall survival, no significant differences were observed. Patients with tumours that had p53 mutations within the L2/L3 domains of the gene showed no significant difference to those with mutations outside the L2/L3 domains for disease-free survival. For overall survival, mutations in the L2/L3 domains showed a marginally significant difference (P = 0.05) in multivariate analysis, but not in univariate analysis (P = 0.13). We conclude that mutation in the L2/L3 domains of the p53 gene is not an independent prognostic indicator of disease outcome for patients suffering from breast cancer with lymph node metastases and positive steroid receptors.

Adult↗
PubMed1999

Organization of the motor centres for the innervation of different muscles of the tongue: a neuromorphological study in the frog.

Cobalt labelling studies on the localization and morphology of the frog's hypoglossal nucleus have revealed three subnuclei. The dorsomedial subnucleus innervates the geniohyoid, hyoglossus, genioglossus and the intrinsic tongue muscles. The ventrolateral subnucleus supplies the sternohyoid, geniohyoid, omohyoid and intrinsic tongue muscles. The intermediate subnucleus innervates the omohyoid, geniohyoid and intrinsic tongue muscles. Neurons innervating protractor, retractor and intrinsic tongue muscles differ in their soma surface area and in their dendritic arborization pattern. It is concluded that there exists a musculotopic organization in the frog's hypoglossal nucleus and that motoneurons subserving different function in tongue movements disclose characteristic morphological differences.

Animals↗
PubMed1998

Focal ischemia enhances the adverse effect potential of N-methyl-D-aspartate receptor antagonists in rats.

Recent clinical trials with non-competitive and competitive N-methyl-D-aspartate (NMDA) receptor antagonists in patients with stroke have shown that these patients develop more adverse effects, particularly psychomimetic effects such as hallucinations and agitation, than normal volunteers at equivalent doses. We therefore examined whether such increased adverse effect potential of NMDA antagonists also occurs in a rat model of permanent focal ischemia. For this purpose, the right middle cerebral artery was occluded under halothane anesthesia, and behavioral alterations in response to the non-competitive NMDA antagonist, MK-801 (dizocilpine), were recorded after recovery from anesthesia. Behavioral alterations in ischemic rats were compared with those in sham-lesioned rats in a blinded fashion. MK-801 (0.4 mg/kg) induced psychomimetic-like stereotyped behaviors which were about twice as intense in ischemic than in non-ischemic rats. A similar trend for enhanced adverse effects was seen with the competitive NMDA antagonist CGS 19755 (Selfotel). Although more NMDA antagonists have to be tested to draw definite conclusions, the present data may indicate that enhanced sensitivity of stroke patients to adverse effects of NMDA antagonists can be predicted by use of a focal ischemia model in rats, thus allowing use of this model for developing novel cytoprotective strategies targeted to minimize glutamatergic excitotoxicity with reduced adverse effect potential.

Animals↗
PubMed1998

LU 73068, a new non-NMDA and glycine/NMDA receptor antagonist: pharmacological characterization and comparison with NBQX and L-701,324 in the kindling model of epilepsy.

The aim of this study was to assess whether a drug which combines an antagonistic action at both NMDA and non-NMDA receptors offers advantages for treatment of epileptic seizures compared to drugs which antagonize only one of these ionotropic glutamate receptors. The novel glutamate receptor antagonist LU 73068 (4,5-dihydro-1-methyl-4-oxo-7-trifluoromethylimidazo[1,2a]quinoxal ine-2-carbonic acid) binds with high affinity to both the glycine site of the NMDA receptor (Ki 185 nM) and to the AMPA receptor (Ki 158 nM). Furthermore, binding experiments with recombinant kainate receptor subunits showed that LU 73068 binds to several of these subunits, particularly to rGluR7 (Ki 104 nM) and rGluR5 (Ki 271 nM). In comparison, the prototype non-NMDA receptor antagonist NBQX (2,3-dihydroxy-6-nitro-7-sulphamoyl-benzo[f]quinoxaline) binds with high affinity to AMPA receptors only. Both NBQX and LU 73068 were about equieffective after i.p. injection in mice to block lethal convulsions induced by AMPA or NMDA. In the rat amygdala kindling model of temporal lobe epilepsy, LU 73068 dose-dependently increased the focal seizure threshold (afterdischarge threshold, ADT). When rats were stimulated with a current 20% above the individual control ADT, LU 73068 completely blocked seizures with an ED50 of 4.9 mg kg(-1). Up to 20 mg kg(-1), only moderate adverse effects, e.g. slight ataxia, were observed. NBQX, 10 mg kg(-1), and the glycine/NMDA site antagonist L-701,324 (7-chloro-4-hydroxy-3-(3-phenoxy)phenyl-quinoline-2(1H)one), 2.5 or 5 mg kg(-1), exerted no anticonvulsant effects in kindled rats when administered alone, but combined treatment with both drugs resulted in a significant ADT increase. The data indicate that combination of glycine/NMDA and non-NMDA receptor antagonism in a single drug is an effective means of developing a potent and effective anticonvulsant agent.

Animals↗
PubMed1997

The health risks of new-wave vegetarianism.

Many young people call themselves vegetarians because they don't eat meat, but the eating style they are adopting is fraught with health risks. In this article, which won CMAJ's 1996 Army Chouinard Memorial Essay Contest for Canadian journalism students, Laura Brydges Szabo looks at the "new vegetarianism" and the recommendations health care professionals are making to young people intent on following this incomplete diet. The contest encourages journalism students to write on health care topics.

Adult↗
PubMed1996

Starch synthesis, and tuber storage protein genes are differently expressed in Solanum tuberosum and in Solanum brevidens.

Studying in vitro stem cuttings of Solanum tuberosum induced for tuberization and those of a non-tuberizing Solanum species, differences both in morphology and in gene expression were detected. Stolon formation essentially depended on light while tuberization was triggered by the elevated level of sucrose in the medium. Genes involved in starch synthesis were induced by sucrose in both species, however, starch granules were detected only in potato. A new tuber specific cDNA clone, GM7, encoding a putative metallocarboxypeptidase inhibitor and the cDNA of a proline rich cell wall protein with S. brevidens specific expression were isolated by differential screening. Sucrose mediated transcription of the tuber storage proteins like patatin and proteinase inhibitors (Kunitz-type, winI, GM7) failed in S. brevidens.

Amino Acid Sequence↗
PubMed1996

[New chemical method for synthesis of O-linked glycopeptides].

The diphenylketone Shiff-base appeared to be a very good protection from amino groups of serine and threonine for glycosylation reaction. O-Glycosides of these amino acids with different monosaccharides, aminosugars and deoxysugars were obtained with excellent yield and very high stereoselectivity. Products of glycosylation reactions were used as building blocks for solid phase glycopeptide synthesis.

Glycopeptides↗
PubMed1995

Maximum and average urine flow rates in normal children--the Miskolc nomograms.

OBJECTIVE: To establish normal reference ranges of urinary flow rates in children. SUBJECTS AND METHODS: From a screening programme, 200 healthy children (96 girls and 104 boys, between 3 and 18 years old) with no renal, urological, psychological or neurological disorders were selected, and they provided 433 micturitions for analysis. The children were divided into those with body surface areas of < 0.92 m2, between 0.92 and 1.42 m2 and > 1.42 m2. The voided volume, maximum and average flow rates of urine were measured. Data were fitted by several mathematical functions and goodness-of-fit determined. RESULTS: The relationship between maximal or average flow rates and voided volume was best fitted by a logarithmic function. The maximal and average urine flow rate nomograms are given in centile form for each body surface area group in both girls and boys. Flow rates showed a close relationship with voided volumes in both sexes and for all body sizes. The average maximal and average flow rates were higher in girls than in boys. CONCLUSION: Normal nomograms of maximal and average urine flow rates of girls and boys at three different body surfaces are presented in centile form. These may be useful for diagnosing lower urinary tract disturbances in children over a wide range of body size and voided volumes.

Adolescent↗
PubMed1993

Levemopamil reduces spatial learning deficit following transient occlusion of common carotid arteries in normotensive rats.

The effect of the calcium channel blocker and 5-HT2 antagonist levemopamil on spatial learning impairment of rats subjected to transient bilateral clamping of carotid arteries (BCCA) was investigated. In addition, the acute effect of BCCA on local cerebral blood flow was measured in the presence and absence of levemopamil in a separate group of rats. Pretreatment with levemopamil prevented the BCCA-induced increase in escape latency during the test trials and ameliorated the BCCA-induced decrease in spatial bias during a probe trial. Under these experimental conditions, local cerebral blood flow fell to near ischaemic values in all mid- and forebrain regions during occlusion of the carotid arteries. However, pretreatment with levemopamil affected the BCCA-induced blood flow changes only in one brain area of 34 investigated. The present data suggest that pretreatment with levemopamil reduces impairment in spatial behaviour and that this effect seems not related to the compound's cerebral vasodilatory action, but to direct neuronal mechanisms.

Animals↗