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Biomedical subjects

I Rácz

Publications and source records attributed to I Rácz.

At least 19 recordsLinked to original sources
PubMed2005

Ischemia reperfusion injury of the skeletal muscle after selective deafferentation.

The present study analyzes the effect of selective deafferentation on the reperfusion injury of the skeletal muscle when nociceptive sensory fibers of the left sciatic nerve are selectively damaged by capsaicin pretreatment in a rat model following tourniquet ischemia (ISC) applied for 30 min, 1 h, and 2 h on the left hind limb. The isometric tetanic contractile force of the extensor digitorum longus (EDL) muscle was measured after 1 h, and 1, 3, or 7 days of reperfusion. Contractile force of the damaged muscle was compared to the intact contralateral muscle. In another group, ISC was used without capsaicin pre-treatment. After 30 min of ISC, there was no difference between deafferented and non-pretreated groups. Following 1 h ISC, with the exception of 1 h reperfusion, the non-pretreated group produced stronger contractions than the deafferented group. After 2 h ISC, the contractile force of the deafferented muscle was significantly stronger compared to the non-deafferented muscle force at all reperfusion times. In conclusions, it was found that the absence of peptidergic sensory fibers after long-lasting (2 h) ischemia is beneficial in reperfusion injury, whereas the absence of vasodilator peptides has unfavorable effects if tissue damage is milder (after 1 h ischemia).

Animals↗
PubMed2003

BGP-15, a hydroximic acid derivative, protects against cisplatin- or taxol-induced peripheral neuropathy in rats.

The neuroprotective effect of BGP-15 against peripheral sensory neuropathy was studied in rats that were exposed to short-term cisplatin or taxol administration. The changes of nerve conduction velocity were determined in situ after treating the Wistar rats with BGP-15 (50, 100, and 200 mg/kg po daily doses throughout the experiment), cisplatin (1.5 mg/kg ip daily dose for 5 days), or taxol (5.0 mg/kg ip daily dose every other day in a 10-day interval) alone or giving the test compound in combination with cisplatin or taxol. Electrophysiological recordings were carried out in vivo by stimulating the sciatic nerve at both sciatic notch and ankle site. Neither motor nor sensory nerve conduction velocity was altered by any dose level of BGP-15 tested. Both anticancer drugs decreased the sensory nerve conduction velocity (SNCV). BGP-15 treatment prevented the impairment of SNCV either in part or totally in the cisplatin- or taxol-treated groups. This neuroprotective potential of BGP-15 could be well correlated with its recently described poly(ADP-ribose) polymerase- inhibitory effect and its ability to protect against the damages induced by the increased level of reactive oxygen species in response to anticancer treatment.

Animals↗
PubMed2003

Time course of leukocyte response and free radical release in an early reperfusion injury of the superior mesenteric artery.

The sequence of changes in circulating immune cells and in free radical production was studied during the small intestine reperfusion. Rat small intestine ischemia/reperfusion was induced by a 45 min superior mesenteric artery occlusion followed by a 4-hour reperfusion. Samples of peripheral blood were collected every 20 min during reperfusion. While the number of polymorphonuclear leukocytes increased significantly both in the sham-operated controls and the experimental group (about 400 per cent at the end of reperfusion), a decrease in lymphocyte counts to 60 per cent was observed in the experimental group only. Although there were no changes in the counts of total T lymphocytes, a significant reduction in B cell counts was observed. Flow-cytometrical measurements showed no changes in the Tc subpopulation, while the Th subpopulation increased in the experimental group only. Free radical generation in blood (luminometric measurements) increased gradually and reached an eight-fold level by the end of reperfusion in both groups. Thus, it has been shown that the increase in free radical production is mainly due to the increased number of polymorphonuclear leukocytes mobilized already at the initial stages of reperfusion. The reduction in B lymphocyte population is probably due to homing mechanisms

Animals↗
PubMed2002

Effect of plasticizer on the dynamic surface tension and the free volume of Eudragit systems.

The purpose of the present study was to determine the changes of dynamic surface tension of aqueous Eudragit dispersions quantitatively and compare these data with the free volume of the free films formed from several dispersions of different dibutyl sebacate (DBS) concentrations. Eudragit L 30D and Eudragit RL 30D aqueous colloidal polymer dispersions and their cast free films were examined. The concentration of DBS varied in the dispersions from 0 to 20%. The dynamic surface tension of the dispersions were measured by the Du Nouy ring method while the free volume of cast films were determined by positron annihilation spectroscopy. The obtained results show that dynamic surface tension measurements indicate the white point (WP) of Eudragit dispersions by a significant standard deviation increase. This may suggest the applicability of dynamic surface tension measurements for the determination of the WP of polymeric dispersions. A decrease in the WP temperature of Eudragit dispersions with an increasing plasticizer concentration was observed up to the DBS concentration of 10% w/w. Above this concentration neither the WP of the polymer dispersion nor the free volume of the free films of the polymer were changed remarkably.

Chemistry, Pharmaceutical↗
PubMed2001

Influence of chlorhexidine species on the liquid crystalline structure of vehicle.

The aim of this study was to investigate the influence of three chlorhexidine species, chlorhexidine base and its salts (diacetate and digluconate), on the physico-chemical features of liquid crystalline systems and on drug transport through lipophilic membranes. Nonionic surfactant, Synperonic A7 (PEG(7)-C(13--15)) was selected for the preparation of the liquid crystalline systems. Mixtures of different ratios of Synperonic A7 and water were prepared. The liquid crystalline systems were characterized using polarizing microscopy, small-angle neutron scattering and transmission electron microscopy. Membrane transport was also examined. The addition of chlorhexidine species to the liquid crystalline system modified the structure of the liquid crystalline system. As a result of liquid crystal--drug interaction, the solubility of chlorhexidine base and its diffusion through lipophilic membranes increased in comparison with those of the chlorhexidine salts.

Chemical Phenomena↗
PubMed2001

Intraspecific invariability of the internal transcribed spacer region of rDNA of the truffle Terfezia terfezioides in Europe.

ITS regions (internal transcribed spacers--ITS1 and ITS2--with the 5.8S gene of the nuclear rDNA) of 25 fruit body samples of Terfezia terfezioides, originating from Hungary and Italy, were compared. The amplification and sequencing of the ITS region was successful with both the ITS1-ITS4 and ITS1F-ITS4 primer pairs. No differences of the restriction fragment length polymorphism profiles were detected among 19 samples collected in one place at the same time. The sequences of the ITS region of 9 samples collected in different localities were highly invariable, differing in only two bases. Thus the intraspecific homogeneity of the ITS region seems to be an important species-specific characteristic of T. terfezioides in contrast to other Terfezia species. As the samples of the species were collected from different and distant localities of Europe, the ITS sequence of T. terfezioides can be considered a very conservative, reliable molecular marker of the fungus.

DNA Primers↗
PubMed2001

Study of the theophylline content of single coated particles by gas chromatography/mass spectrometry.

The aim of the present study was to determine by gas chromatography/mass spectrometry (GC/MS) the content uniformity of single theophylline microcapsules of different particle size ranges. Microencapsulation was carried out in a laboratory fluidized bed system using Eudragit L30D aqueous dispersion. Scanning electron microscopy was applied for the characterization of the surface morphology of the prepared theophylline microcapsules of two different particle size ranges. The theophylline content of single particles was determined by GC/MS analysis. It was found that the particle size of microcapsules greatly influenced their theophylline content. The GC/MS analysis was successully applied to indicate the changes in the content uniformity and thus the interparticular costing distribution of single theophylline microcapsules in the presence of several excipients.

Calibration↗
PubMed2001

[Surgical resection of tumors in the distal duodenum].

We present six cases of successfully resected primary tumors of the distal part of duodenum (third and fourth segment). Average age of the four male and two female patients was 59 years (47-80). Distal segmental resection were performed in four, pylorus-preserving pancreatoduodenectomy in two cases. Histologically the tumors were five adenocarcinomas, and one gastrointestinal stromal tumor. This tumor causing massive bleeding. In two patients, local lymph nodes were tumor positive, and in one patient synchronous metastasis of the greater omentum was excised during a palliative resection. There was no operative mortality. During a mean follow-up period of 17 months two patients died. Our results support the fact, that radical surgical resection of these tumors, even by segmental resection, provides a more favorable prognosis for duodenal carcinoma than for pancreatic tumors.

Adenocarcinoma↗
PubMed2001

[Preformulation study of atenolol-containing solutions.. I. The pH dependence of thermostability].

The stability of atenolol solutions was evaluated under accelerated isothermal degradation conditions at 90 degrees C. A specific and sensitive HPLC method was adapted to study the pH dependence of the stability. The maximum stability of atenolol was achieved at pH 4 with a k value of 1.1 x 10(-3) h-1. The degradation of atenolol followed first-order kinetics at above mentioned conditions.

Atenolol↗
PubMed2000

The effect of liquid crystalline structure on chlorhexidine diacetate release.

The aim of this study was to examine different liquid crystalline preparations containing chlorhexidine diacetate and to find connection between their structure and the kinetic of drug release. Nonionic surfactant, Synperonic A7 (PEG(7)-C(13-15)) was selected for the preparation of the examined liquid crystalline systems. Mixtures of different ratios of Synperonic A7 and water were produced. By increasing the water content of the systems, lamellar and hexagonal liquid crystal structures were observed. For the analysis of the prepared liquid crystalline systems polarising microscopy, rheology study, differential scanning calorimetry and dynamic swelling tests were carried out. The chlorhexidine diacetate release was examined by Franz-type vertical diffusion cell apparatus. The chlorhexidine diacetate release from hexagonal liquid crystalline preparations was characterised by zero-order release kinetics, while the drug release from lamellar liquid crystalline systems was described by anomalous (non-Fickian) transport. The results indicate that the drug release kinetic is strongly dependent on the liquid crystalline structure.

Anti-Infective Agents, Local↗
PubMed2000

The effect of temperature and polymer concentration on dynamic surface tension and wetting ability of hydroxypropylmethylcellulose solutions.

The purpose of the present study was to evaluate quantitatively the changes of dynamic surface tension and contact angle of hydroxypropylmethylcellulose (HPMC) aqueous solutions as a function of temperature and polymer concentration of the examined solutions. HPMC aqueous solutions of different concentrations (1%, 2%, 3%, 4% w/w) were prepared without plasticizer and with 1% w/w Lutrol F127. Dynamic surface tension of the prepared solutions was determined by the Du Nouy ring method of the KSV Sigma 70 computer-controlled and programmable tensiometer. The dynamic contact angle of Avicel PH-101 tablets was measured against HPMC solutions of various concentrations by the plate method of the KSV Sigma 70 tensiometer. The obtained results indicate that dynamic surface tension measurement can be applied for the accurate determination of the thermal gelation temperature of the prepared HPMC solutions. With increasing concentration of HPMC, dynamic contact angle values of solutions also increased, thus decreasing the spreading behavior on the surface of Avicel tablets.

Anticholesteremic Agents↗
PubMed2000

Effect of the wettability characteristics of polyethylene glycol derivatives on the drug release of wax matrices.

The purpose of the present work was to study the relationship between the physicochemical characteristics of different polyethylene glycol aqueous solutions and the kinetics of potassium chloride release from wax matrix samples containing polyethylene glycol derivatives. Potassium chloride was embedded into thermosoftening matrix material to produce a sustained-release dosage form. Potassium chloride release was measured by the rotating paddle method of USP 23 and the dissolution process was characterized by a modified Nernst equation. Physicochemical characteristics--surface tension, dynamic contact angle, viscosity--of the polyethylene glycol aqueous solutions were also determined. The results indicate that the adhesion tension of surfactant containing aqueous solutions has a decisive impact on the prediction of the potassium chloride release rate from wax matrices.

Adhesiveness↗