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Biomedical subjects

M Rehák

Publications and source records attributed to M Rehák.

13 recordsLinked to original sources
PubMed2006

[Delivery of gentamicin to the rabbit eye using hydrogel and iontophoresis].

The aim of this study was to evaluate the use of solid hydrogel as a probe for the drug delivery to the rabbit eye upon application of low current iontophoresis. Hydroxyethyl methacrylate (HEMA), cross-linked with ethylenglycol dimethacrylate (EGDMA) were prepared to form solid hydrogels. The concentrations of gentamicin sulfate in different segments of rabbit eye after transconjunctival and transscleral iontophoresis were also studied. For iontophoresis we used a portable Mini Ion device (designed at Hebrew University of Jerusalem) and applied a current from 0 mA to 1.5 mA for pre-set period from 30 to 120 seconds and after application the concentrations of gentamicin in cornea were assayed. The rabbits in control group were treated with fortified gentamicin eye-drops (concentration 1.4 %). The highest concentration of gentamicin sulfate was reached after iontophoresis with current intensity of 1.5 mA applied for 60 s. High gentamicin concentration were found in the retina and in the sclera four hours after transscleral iontophoresis, the lowest concentration was obtained in vitreous. The delivery of gentamicin to the eye via iontophoresis with solid HEMA/EGDMA hydrogels seems to be promising method achieving high concentrations of the drug in the eye tissue.

Animals↗
PubMed2006

[Ocular sparganosis in the Czech Republic--a case report].

The authors report a case of 14-year-old boy presented to the Ophthalmologic Department of University Hospital in Olomouc with the diagnosis af acute anterior uveitis. A living parasite has been detected in the anterior chamber in a slit lamp examination. The vitreous and retina remained uninvolved. The acute iridocyclitis associated with parasitic infection is a very rare cause of anterior uveitis in Central Europe. The patient underwent surgical removal of the parasite via paracentesis. The inflammation resolved under the treatment with atropine and dexamethasone drops within a few days. Histopathological examination revealed the parasite as a young larval stage of tapeworm from family Pseudophyllidea (sparganum). Based on the analysis of development cycles of different types of tapeworms and according the literature data on tapeworms found in the Czech Republic genus Spirometra seemed to be the most plausible cause of the patient's disease. As the most probable source of viable parasites authors suspect swallowed water containing tiny infected crustaceans in the dam near the town Olomouc in Moravia.

Adolescent↗
PubMed2001

[Videothoracoscopy and video-assisted surgical procedures in penetrating injuries of the thorax].

Diagnosis and treatment of the penetrating injury of the chest is quite difficult. In all types/sizes of hospitals/these injuries has to be immediately treated in surgery departments. Often decision about the optimal treatment of these injuries is quite difficult. In this paper experience with 37 cases of penetrated trauma is presented. Authors defined adequate criteria for selection of the chest tube, videothoracoscopy, video-assisted thoracic surgery (VATS), emergency thoracotomy and thoracophrenolaparotomy.

Adult↗
PubMed1998

Binding of avidin modified antibody to biotinylated metal supported membranes and liposomes changes the physical properties of lipid bilayer.

Various methods have been applied to study the physical properties of metal supported bilayer lipid membranes (s-BLM) and large unilamellar liposomes containing biotinylated phospholipids during the binding of IgG modified by avidin. Electrostriction method applied to s-BLM showed that addition of avidin-IgG (A-IgG) complex in a small concentration (0.2 mumol/l) resulted in an approximately twofold decrease of membrane capacitance, C, increase of elasticity modulus in direction perpendicular to the membrane plane, E perpendicular, by 5-20%, increase in intrinsic membrane potential, delta phi m, by approximately 30 mV, and an approximately 5-15% increase of the coefficient of dynamic viscosity, eta. The method of ultrasonic velocimetry showed that addition into the suspension of liposomes of unmodified IgG did not induce any changes in ultrasound velocity, while addition of A-IgG complex in a concentration range of 0-1 mumol/l led to an increase of the velocity number [u]. The plot of changes of [u] versus A-IgG concentration has a tendency to saturate at concentrations above 0.5 mumol/l, which suggests long-range interactions in the membrane induced by strong binding of A-IgG to the biotin sites on the membrane. Probably, this binding leads to a decrease of the coefficient of adiabatic compressibility of liposomes.

Avidin↗
PubMed1997

Electrochemical evaluation of chemical selectivity of glutamate receptor ion channel proteins with a multi-channel sensor.

A new method for evaluating chemical selectivity of agonists towards receptor ion channel proteins is proposed by using glutamate receptor (GluR) ion channel proteins and their agonists N-methyl-D-aspartic acid (NMDA), L-glutamate, and (2S, 3R, 4S) isomer of 2-(carboxycyclopropyl)glycine (L-CCG-IV). Integrated multi-channel currents, corresponding to the sum of total amount of ions passed through the multiple open channels, were used as a measure of agonists' selectivity to recognize ion channel proteins and induce channel currents. GluRs isolated from rat synaptic plasma membranes were incorporated into planar bilayer lipid membranes (BLMs) formed by the folding method. The empirical factors that affect the selectivity were demonstrated: (i) the number of GluRs incorporated into BLMs varied from one membrane to another; (ii) each BLM contained different subtypes of GluRs (NMDA and/or non-NMDA subtypes); and (iii) the magnitude of multi-channel responses induced by L-glutamate at negative applied potentials was larger than at positive potentials, while those by NMDA and L-CCG-IV were linearly related to applied potentials. The chemical selectivity among NMDA, L-glutamate and L-CCG-IV for NMDA subtype of GluRs was determined with each single BLM in which only NMDA subtype of GluRs was designed to be active by inhibiting the non-NMDA subtypes using a specific antagonist DNQX. The order of selectivity among the relevant agonists for the NMDA receptor subtype was found to be L-CCG-IV > L-glutamate > NMDA, which is consistent with the order of binding affinity of these agonists towards the same NMDA subtypes. The potential use of this approach for evaluating chemical selectivity towards non-NMDA receptor subtypes of GluRs and other receptor ion channel proteins is discussed.

Animals↗
PubMed1997

Stability of bilayer lipid membranes on different metallic supports.

In order to arrive at an optimized s-BLM protocol, the influence of various metallic supports (silver, iridium and stainless steel) of different diameters (from 0.14 to 0.33 mm) on the process of forming and stability of supported phospholipid bilayer membranes was studied. In addition, experiments were made using different membrane-forming solutions, ionic strength and pH. The transmembrane resistance and the current ratio between bare and lipid-coated wire at +670 mV were measured. Teflon-coated stainless steel support (0.33 mm in diameter) covered with 2% crude ox brain fraction of phospholipids was most convenient for the formation of supported bilayer lipid membranes on solid support. The well-known stabilizing effect of cholesterol was confirmed for the s-BLM system. Both the pH in the range 5.0-8.0 (silver and stainless steel supports) and the ionic strength (for all types of supports) in the range from 0.025 to 0.1 mol/l at pH 7.0 were found not to be crucial.

Hydrogen-Ion Concentration↗
PubMed1994

Application of biotin-streptavidin technology in developing a xanthine biosensor based on a self-assembled phospholipid membrane.

We have designed an amperometric xanthine minibiosensor based on a supported biotinylated phospholipid membrane. To this membrane streptavidin-modified xanthine oxidase was coupled. The fabricated biosensor corresponds in shape and size to a needle of 0.3 mm in diameter. The assay is based on the electrochemical detection of enzymatically generated hydrogen peroxide. The response to xanthine was linear up to 1 mmol.l-1 with a detection limit of 0.02 mmol.l-1. The response time was less than one minute and the biosensor was stable for at least five days.

Bacterial Proteins↗
PubMed1993

Design of a glucose minisensor based on streptavidin-glucose oxidase complex coupling with self-assembled biotinylated phospholipid membrane on solid support.

A simple and fast procedure to prepare a glucose-sensitive minielectrode is presented. It is based on a biotin-modified phospholipid bilayer to which a streptavidin-glucose oxidase complex is coupled. The assay is based on the electrochemical detection of enzymatically generated hydrogen peroxide at the potential +670 mV. In the case of an air-saturated buffering solution the response to glucose was measured up to 50 mmol.L-1, with a linear portion up to 7 mmol.L-1. The influence of oxygen tension, pH, and temperature as well as possibly interfering substances was investigated. The prospect usage for the measurement of blood and urine was tested.

Bacterial Proteins↗
PubMed1991

Influence of hypergravity on the pH profile and proteolytic activity of the avian gastrointestinal tract.

The present study deals with the effect of hypergravity (2xg) on the pH and on the proteolytic activity in the digesta of the gastrointestinal tract of Japanese quails during intense growth. The birds were raised on a semisynthetic diet containing free amino acids (A) and a commercial diet (B). During days 35 till 40 post-hatching the quails were exposed to hypergravity (2xg) using a specially designed centrifuge. On days 40 (experimental group, 2xg) and 41 (control group, 1xg) the animals were sacrificed. The pH of the digesta in various segments of the gastrointestinal tract was measured by means of a semi-microelectrode. Total proteolytic activity was determined by means of azo-dye-modified proteins serving as general proteolytic substrates. Hypergravity leads in general to an alkalization of digesta in various parts of the gastrointestinal tract. In case of the gizzard and duodenum (diet A) and also in the distal jejunum (diet B) the differences are significant. With both diets, hypergravity leads to a considerable decrease in the total proteolytic activity. The reduction is most expressed in the duodenum and jejunum. Changes in the pH of digesta compensate for the decrease in the proteolytic activity. This may explain why hypergravity per se does not seem to impair growth of the Japanese quails.

Amino Acids↗
PubMed1989

[Cervical vertebrae replacements].

The authors analyze caused and indications for prostheses of bodies of cervical vertebrae. As caused they mention bone tumours, metastases, benign bone tumours and injuries. For operation they indicate patients with neurological symptoms and instability of the spine. For prostheses they use bone grafts from the blade of the ilium. They insert the graft during traction, as described by Crutchfield and do not routine fix it. After operation they immobilize by "Minerva" for three weeks. The method is in case of metastases and bone tumours only palliative, but improves the patients' mobility and prevents the development of early neurological complications.

Bone Transplantation↗