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Biomedical subjects

G Nagy

Publications and source records attributed to G Nagy.

At least 37 records · Page 2Linked to original sources
PubMed2002

Biochemical alterations in cerebrospinal fluid during thoracoabdominal aortic cross-clamping in dogs.

Spinal cord damage during and after thoracoabdominal aortic cross-clamping continues to be a major problem. Somatosensory and motor evoked potentials have been used to monitor spinal cord function but their value for predicting paraplegia has been controversial. The aim of this study was to measure biochemical markers in the cerebrospinal fluid (CSF) and correlate changes with spinal cord ischemia. Since neural tissue utilizes only glucose as substrate for its metabolism and energy supply, we measured changes of metabolites of anaerobe glycolysis. In a canine model in which general anesthesia was used, the thoracoabdominal aorta was cross-clamped proximally and distally for 60 min. Hemodynamic parameters, blood gases, and glucose level were monitored continuously. Blood and CSF sampling were performed at baseline, at 15, 30, and 55 min during cross-clamping, and at 5 and 15 min after aortic declamping. Levels of lactate (1.7 +/- 0.1 to 3.2 +/- 0.3 mmol/L), pCO2 (43 +/- 2 to 35 +/- 1.6 mmHg), and neuron-specific enolase (NSE) (5.17 +/- 0.5 to 13.0 +/- 3.5 mg/L) in CSF showed significant changes (p < 0.05) during clamping and reperfusion. Changes in CSF lactate and NSE levels correlate with the duration of spinal cord ischemia. These markers of ischemic metabolism appear suitable to monitor the degree of spinal cord ischemia during thoracoabdominal cross-clamping and may be useful to predict the efficacy of preventive methods.

Animals↗
PubMed2002

A comparison of the shaping characteristics of two nickel-titanium endodontic hand instruments.

AIM: The purpose of this study was to compare the shaping characteristics of Ni-Ti K-files and Ni-Ti S-files manipulated by hand. METHODOLOGY: A total of 60 extracted human roots were embedded in resin blocks. The embedded roots were divided into three groups: (i) roots with straight; (ii) apically curved; and (iii) continuously curved canals. Each of the three groups was randomly divided into two subgroups; one subgroup in each group was prepared with Ni-Ti K-files and the other with Ni-Ti S-files. The files were used with a step-back technique and enlarged so that the master apical file was size 30, and the canals were stepped back to size 40. The performance of the files was assessed by the superimposition of projected radiographs taken in bucco-lingual and mesio-distal directions before and after the preparation. The results were analysed statistically using analysis of covariance and Duncan's multiple range test. RESULTS: Although canal preparation using Ni-Ti K-files was quicker, there were no statistically significant differences between file types. The Ni-Ti S-file removed significantly more material at the most coronal level (P < 0.05). There were minor differences between instruments at the apical level. Only in the proximal view of apically curved canals prepared with Ni-Ti S-files was significantly more dentine removed from the outer aspect of the curvature (P < 0.05). At the middle level (wide danger zone) the Ni-Ti S-files removed more dentine from the inner aspect of the curvature in those roots with apically curved canals. CONCLUSIONS: Under the conditions of this study, preparation with Ni-Ti K-files produced more appropriate shapes in roots with apically curved canals than Ni-Ti S-files.

Analysis of Variance↗
PubMed2002

Effects of a non-starch polysaccharidase enzyme preparation from Thermomyces lanuginosus on energy and protein metabolism and milk yield of dairy cattle.

Non-starch polysaccharides (NSPs) form an integral part of the cell walls in plants and represent considerable available energy when degraded into absorbable mono-, di-, tri- and oligosaccharides. The ruminal microflora hydrolyses a good part of NSPs, however, recently there have been attempts to enhance the rate of utilisation by using external polysaccharidase enzymes. In the present study the effects of an enzyme preparation (Rumino-Zyme) high in xylanase activity were studied on ruminal volatile fatty acid (VFA) concentration, parameters of energy and protein metabolism, milk yield, feed conversion ratio (FCR) and body condition score of high-yielding dairy cows. A lignolytic enzyme preparation produced by the thermophilic fungus Thermomyces lanuginosus was applied in the present experiment and fed to dairy cows at 34 g/day dosage in the period between calving and the 110th day of lactation. This preparation increased VFA concentration in the rumen from about 32 days after calving and onward. Increased VFA concentration was followed by an about 5 to 10% increase in milk production and an almost 0.1% increase in butterfat production. Increased VFA concentration produced more balanced energy metabolism in the experimental cows as indicated by the lower incidence rate of hyperketonaemia, and lower acetoacetic acid and non-esterified fatty acid (NEFA) concentration in the blood of the experimental cows. Aspartate aminotransferase (AST) activity was tendentiously higher in the control group and the proportion of cows that had AST activity higher than 100 U/l was also higher in the control group. Both control and experimental cows showed balanced protein and acid-base metabolism throughout the experiment. Enhanced VFA concentration contributed to an improvement in energy balance in the experimental cows with a resultant improvement of feed intake and feed utilisation. Due to the more balanced energy metabolism postparturient body condition loss of the treated cows was reduced.

Acetoacetates↗
PubMed2002

Interdependent chemical-electrochemical steps in retrometabolism-based drug and safer chemical design.

An extension of the retrometabolic based drug (chemical) design concept, specifically the soft drug approach, to the family of nitrone compounds is presented. Nitrones oppose oxidative challenges by virtue of their ability to very rapidly trap free radical species that are more stable and biochemically less harmful than the original molecular fragments. Moreover, the spin adducts may undergo further transformations including reaction with a second radical and decomposition (hydrolysis) to hydroxylamines and carbonyl compounds. Nitrones and their spin adducts may generate nitric oxide in vivo, which, like nitrones themselves, exerts a number of diverse activities in phylogenetically distant species as well as opposing effects in related biological systems. It was described as a major messenger in the cardiovascular, immune, and nervous systems, in which it plays regulatory, signaling, cytoprotective, and cytotoxic effects. Nitrones play an important role in the synthesis of drugs belonging to chemically and pharmacologically very different classes. A combined chemical-electrochemical synthesis of nitrones has been elaborated. These compounds may be obtained from aldehydes or ketones and N-substituted hydroxylamines. These reactions were performed directly, in situ in the electrochemical cell, where phenylhydroxylamine obtained by electroreduction of nitrobenzene derivatives reacts with the carbonyl compound introduced in the cell. The kinetic and thermodynamic parameters of the processes were determined by analyzing the adequate polarographic curves. Differences between purely chemical and mixed chemical-electrochemical methods are discussed. Analysis of the experimental data permits optimization of the investigated process from a preparative point of view. Effects of structural factors were systematically evaluated. The proposed method may be useful for combinatorial chemistry as well.

Algorithms↗
PubMed2001

[Clinical, microbiological and therapeutic aspects of oral candidiasis (candidosis)].

Exogenic, prosthetical and endogenic factors that may influence and facilitate fungal infections of the oral cavity are summarized. The clinical classification of the oral candidiasis is based on the criteria accepted in the international literature. The main points for the classification are the clinical appearances, the histopathological alterations and the possible manifestation of an underlying disease. In the last part of the review a brief summary is given on the antifungal agents such as polyenes, azole-derivatives and DNA analogs available for candidiasis.

Antifungal Agents↗
PubMed2001

[Molecular pathogenesis of oral candidiasis (candidosis)].

Candida species are the most important pathogenic fungi in the oral cavity with the predominance of Candida albicans. In this review the authors summarise the most important cell-surface bound pathogenical factors such as fibrinogen, fibronectin, thrombin, collagen, laminin and vitronectin-binding proteins and extracellular virulence enzymes of Candida albicans and some microbiological aspects of oral candidiasis (candidosis). Adherence to both artificial and mucosal surfaces is mediated by hydrophobic interactions and by ligand-receptor attachment. Surface bound proteins on Candida cells bind to mucosal surface proteins. Broad spectrum antibacterial treatment liberates binding sites for Candida colonisation by means of reducing the number of bacterial normal flora in the oral cavity. Non immune humoral factors such as iron, lysosyme, hystidine-rich-polypeptides, lactoferrin, lactoperoxidase and immune globulins such as s-IgA, moreover, elements of cellular immunity, especially polymorphonuclear leucocytes contribute to preventing the establishment of Candida infection. A disbalance in these constituents may result in colonisation and biofilm production of Candida. The biofilm consist of serum proteins mainly fibrin, desquamated epithelial cells, dead leukocytes, living and multiplying candida cells, pseudohyphae and extracellular matrix excreted by candida cells. Living candida cells are deeply embedded in the biofilm, thus protected from defence mechanisms of the host. Continuous destruction of mucosal surfaces beneath the biofilm may create a portal of entry for systematic candidal infections.

Candidiasis, Oral↗
PubMed2001

Analytical performance characteristics of thin and thick film amperometric microcells.

The analytical performance of amperometric microcells with different electrode geometries is compared for enzyme activity measurements. The microcells were fabricated with thin film photolithography or thick film screen-printing in four different designs. The cells made with the thin film process used flexible substrate with microelectrode array or a circular, disk-shaped working electrode. The screen-printed working electrodes had semicircle or disk shape on ceramic chips. Putrescine oxidase (PUO) activity measurement was used as a model. The determination of PUO activity is important in the clinical diagnosis of premature rupture of the amniotic membrane. An electropolymerized m-phenylenediamine size-exclusion layer was used to eliminate common interferences. The size exclusion layer revealed also to be advantageous in protecting the electrodes from fouling by putrescine (enzyme substrate). The electrode fouling of bare electrodes was insignificant for screen-printed electrodes, but very severe for electroplated platinum working electrodes. The microelectrode array electrodes demonstrated smaller RSD and higher normalized sensitivities for hydrogen peroxide and PUO activity. All the other electrodes were demonstrating comparable analytical performances.

Electrochemistry↗
PubMed2001

Synthesis and antibacterial study of unsaturated Mannich ketones.

Several Mannich ketones of 2-arylmethylenecycloalkanones were synthesised using the classical acid-catalysed Mannich reaction. Antibacterial activity of these new water-soluble compounds was reported against Pseudomonas aeruginosa, Escherichia coli, Staphylococcus aureus, Staphylococcus saprophyticus, Micrococcus luteus and Bacillus subtilis standard strains. Human cell line cytotoxicity of our new compounds was evaluated against HeLa cell lines. Some compounds showed low cytotoxicity (41.52 nM mL(-1) for 14 and 46.60 nM mL(-1) for 18) and proved to be efficient antibacterial agents against the Gram-positive strains. Minimum inhibitory concentrations varied from 1.56 to 100 microg mL(-1). The mechanism of action was examined, too.

Bacillus subtilis↗
PubMed2001

Expression of hemin receptor molecule ChuA is influenced by RfaH in uropathogenic Escherichia coli strain 536.

The outer membrane protein ChuA responsible for hemin utilization has been recently identified in several pathogenic Escherichia coli strains. We report that the regulatory protein RfaH influences ChuA expression in the uropathogenic E. coli strain 536. In an rfaH mutant, the chuA transcript as well as the ChuA protein levels were significantly decreased in comparison with those in the wild-type strain. Within the chuA gene, a consensus motif known as the JUMPStart (just upstream of many polysaccharide associated gene starts) sequence was found, which is shared by RfaH-affected operons. Furthermore, the presence of two different subclasses of the chuA determinant and their distribution in E. coli pathogroups are described.

Bacterial Outer Membrane Proteins↗
PubMed2001

Evidence of prolactin immunoreactivity in the bone marrow of untreated multiple myeloma patients.

The role of prolactin (PRL) in the physiological regulation of the immune system and in hematopoiesis is well known. There is also evidence of the significance of PRL in several pathological conditions such as autoimmune diseases and some malignancies, e.g. colon and breast carcinomas and also B cell malignancies. Multiple myeloma is known as a B cell malignancy. It is the result of malignant transformation of a single clone of neoplastic plasma cells that synthesize abnormal amounts of monoclonal immunoglobulins or immunoglobulin fragments. In our present studies, the possible expression of PRL in bone marrow cells obtained from diagnosed multiple myeloma (17 cases) or nonmyeloma (5 cases) patients was examined by the method of immunocytochemistry. Samples obtained from those multiple myeloma patients (13 cases) who had not received chemotherapy for 6 months prior to these studies showed a positive immunocytochemical reaction for PRL. Bone marrow smears of patients diagnosed with multiple myeloma who had received chemotherapy within 6 months of the study and also the smears of patients without diagnosed multiple myeloma failed to show a positive immune reaction for PRL. In the case of a patient who was examined prior to and also after a period of 3 months of chemotherapy, the PRL-immunopositive bone marrow cells had disappeared due to the treatment. According to the light microscopic analysis of the cell morphology, PRL-immunopositive cells in the bone marrow were mainly, but not exclusively, plasma cells. There was no correlation between the positive PRL staining of cells and the type of monoclonal immunoglobulin or the ratio of plasma cells detected in the bone marrow. Taken together, our results indicate a possible role of PRL in multiple myeloma. Further experiments are necessary to identify the prognostic value of PRL in multiple myeloma.

Adult↗
PubMed2001

Pharmacokinetics and bioavailability of doxycycline in fasted and nonfasted broiler chickens.

The pharmacokinetics and the influence of food on the kinetic profile and bioavailability of doxycycline was studied after a single intravenous (i.v.) and oral dose of 10.0 mg/kg body weight in 7-week-old broiler chickens. Following i.v. administration the drug was rapidly distributed in the body with a distribution half-life of 0.21 +/- 0.01 h. The elimination half-life of 6.78 +/- 0.06 h was relatively long and resulted from both a low total body clearance of 0.139 +/- 0.007 L/h.kg and a large volume of distribution of 1.36 +/- 0.06 L/kg. After oral administration to fasted chickens, the absorption of doxycycline was quite fast and substantial as shown by the absorption half-life of 0.39 +/- 0.03 h, the maximal plasma concentration of 4.47 +/- 0.16 micrograms/mL and the time to reach the Cmax of 1.73 +/- 0.06 h. The distribution and the final elimination of the drug were slower than after i.v. administration. The absolute bioavailability was 73.4 +/- 2.5%. The presence of food in the intestinal tract reduced and extended the absorption (t1/2a = 1.23 +/- 0.21 h; Cmax = 3.07 +/- 0.23 micrograms/mL; tmax = 3.34 +/- 0.21 h). The absolute bioavailability was reduced to 61.1% +/- 4.4%.

Administration, Oral↗
PubMed2001

Pathogenesis, microbiological and clinical aspects of oral candidiasis (candidosis).

The clinical significance of the oral candidiasis (either as independent disorder, or as a part of another disease) is increasing with time. The diagnosis and local treatment of the oral candidiasis may not be satisfactory, this disorder cannot be eliminated without the correct diagnosis and management of the underlying disease. At the same time, some disorders, such as Candida induced leukoplakia, may significantly enhance tumor development. Fungal infection of the mouth is often the initial sign of several immunodeficiency diseases. It is, therefore, very important to clarify the background of a fungal infection, since this may be critical regarding the prognosis.

Antifungal Agents↗
PubMed2001

[Comparative epidemiologic examination of caries in adolescents].

The aim of the study was to assess the caries prevalence and oral hygiene in groups of adolescents living in two Hungarian towns and to establish correlations with socio-economical factors. Examinations of caries and oral hygiene were performed in 586 14-16-year-old children. The percentage of caries free children was 5.1%, the DMFT and DMFS values were 6.97 +/- 4.67 and 9.95 +/- 7.94 respectively. The VPI index was 41.6 +/- 32.7% (mean +/- S.D.), and showed positive correlation with the caries prevalence. The DMFT and DMFS values, as well as VPI decreased as the educational level of the father had increased. The number of siblings had a worsening effect on DMFT, DMFS and VPI values.

Adolescent↗
PubMed2001

[Surgical considerations in type-B aortic dissection].

Inspite of remarkable progress in both diagnostic and therapeutic development in treating aortic dissections this continues to be one of the most severe vascular catastrophies complicated by high mortality. While aortic dissections Type A are to treat surgically in our days, in majority of patients with Type B dissections hypotensive treatment is the method of choice providing better chance for survival preventing effectively aneurysm formation and rupture at the site of intimal tear. However in certain cases Type B dissection produces either isthmic aneurysm formation, or with distal progression may afflict long segmental thoracic, thoracoabdominal or abdominal deterioration of the aorta and its side branches. The spinal, visceral, renal and lower limb ischemia threatens viability of these organs and hypotensive medication may enhance risk. Prompt evaluation and selection of these cases with proper surgical reconstruction help us to reduce mortality. At our department we have performed 33 thoracoabdominal endoaortectomies with meticulous reconstruction of renal and visceral orifices. The mortality rate in this subgroup of patients was 6%, meanwhile almost 70% in those, treated medically but had the severe distal branch involvement. Based on our experiences in selected patients with Type B aortic dissections we recommend this procedure in order to achieve improvement of results.

Adult↗
PubMed2001

[Suckling-induced changes in oxytocin and alpha-melanocyte-stimulating hormone contents of the median eminence and various lobes of the pituitary gland].

Previous reports have implicated that pituitary-derived prolactin (PRL) is secreted from two distinct zones of mammotropes within the anterior lobe (AL). The inner zone (AL-IZ), located adjacent to the NIL, is supposed to be involved in the rapid and massive discharge of PRL from the pituitary gland due to suckling stimulus. Anatomically, the AL-IZ has an intimate contact with the NIL because the blood arriving from the posterior pituitary through the short portal vessels (SPV) baths it first. Based on these facts it would be hypothesized that the locally released and/or produced important compounds, like oxytocin (OXT) and alpha-melanocyte-stimulating hormone (alpha-MSH), can be delivered to the AL-IZ. Therefore, the purpose of this study was to examine the possible local transportation of these hormones into various regions of the pituitary gland (adenohypophysis inner-zone (AL-IZ), outer zone (AL-OZ), intermediate lobe (IL), neural lobe (NL)) and median eminence of lactating rats. We have measured the concentration of OXT and alpha-MSH from tissue samples of nonsuckled and suckled rats using specific RIA-s. There were no changes in the concentration of OXY and alpha-MSH in the AL-IZ and AL-OZ due to suckling stimulus. In contrast, our data provide compelling evidence that OXT is transported into the IL, which can be further increased by suckling stimulus. Our data have shown a lack of local delivery of either alpha-MSH or OXY into the AL that raises serious doubt about their possible role in PRL secretion during suckling stimulus.

Animals↗
PubMed2000

Measurement of intracellular interferon-gamma and interleukin-4 in whole blood T lymphocytes from patients with systemic lupus erythematosus.

Contradictory data are available about the dominance of T-helper 1 (T(H)1), or T-helper 2 (T(H)2) cytokines in systemic lupus erythematosus (SLE). Therefore, intracellular interferon-gamma (IFN-gamma) and interleukin-4 (IL-4) production of T lymphocytes was measured in whole blood of healthy donors and active and inactive SLE patients by flow cytometry. The percentage of IFN-gamma and IL-4 positive cells was low (<1%) in unstimulated samples of the healthy controls, while that of IFN-gamma and IL-4 positive cells in the stimulated cells was 25.2+/-10.6% and 0.6+/-1.5%, respectively. No significant difference was found between SLE patients and healthy controls and between active and inactive patients in these parameters either in the unstimulated or in the stimulated samples. One patient with severe disease had as high as 11.8% IL-4 positive cells and 12.5% IFN-gamma positive cells in the stimulated samples, but after the initiation of intensive corticosteroid and cytostatic therapy, the percentage of IL-4 positive T cells decreased (4.76%) while that of IFN-gamma positive T cells increased (47.91%). We conclude that the intracellular IL-4 and IFN-gamma expression of T lymphocytes does not differ markedly between SLE patients and healthy controls, with the possible exception of severe disease, when marked IL-4 overproduction may exist beside low IFN-gamma production. Furthermore, corticosteroid and cytostatic therapy might normalize this altered IFN-gamma/IL-4 ratio.

Adult↗