Biomedical subjects

P Bures

Publications and source records attributed to P Bures.

13 recordsLinked to original sources

PubMed2000

Hydrogels in pharmaceutical formulations.

The availability of large molecular weight protein- and peptide-based drugs due to the recent advances in the field of molecular biology has given us new ways to treat a number of diseases. Synthetic hydrogels offer a possibly effective and convenient way to administer these compounds. Hydrogels are hydrophilic, three-dimensional networks, which are able to imbibe large amounts of water or biological fluids, and thus resemble, to a large extent, a biological tissue. They are insoluble due to the presence of chemical (tie-points, junctions) and/or physical crosslinks such as entanglements and crystallites. These materials can be synthesized to respond to a number of physiological stimuli present in the body, such as pH, ionic strength and temperature. The aim of this article is to present a concise review on the applications of hydrogels in the pharmaceutical field, hydrogel characterization and analysis of drug release from such devices.

Animals↗

PubMed1995

[Ca(2+)-channel blockers and binding of tricyclic antidepressive agents].

The interactions between Ca(2+)-channel blockers (verapamil and gallopamil) and synaptic plasma membranes (SPM) from bovine brain or human lymphocyte and platelet plasma membranes were studied. Changes in binding parameters of [3H]imipramine, [3H]desmethylimipramine and [3H]gallopamil were determined after addition of unlabelled verapamil or imipramine and after addition of phosphatidylserine (PS) (PS-stimulation). Specific binding of [3H]imipramine to SPM was decreased and [3H]desmethylimipramine binding was increased by 1 microM verapamil. [3H]gallopamil binds specifically to SPM as well as to platelet and lymphocyte membranes. [3H]gallopamil binding to SPM or lymphocyte plasma membranes was PS-stimulated in contrast to platelet plasma membranes without PS effect on binding. Imipramine inhibited both [3H]gallopamil binding and PS-stimulated [3H]gallopamil binding to SPM or lymphocyte plasma membranes. Mutual effects of tricyclic antidepressants and Ca(2+)-channel blockers on their binding sites require relatively high drug concentrations. Mechanism of Ca(2+)-channel blockers action in the treatment of depression may be connected rather with changes in signal transduction through serotonin and catecholamine receptor systems than with direct interaction of drugs with binding sites for tricyclic antidepressants.

Animals↗

PubMed1993

[The effect of cocaine on binding of tricyclic antidepressives in the synaptic plasma membranes in the brain].

Effect of cocaine on binding of 3H-imipramine, 3H-desmethylimipramine, 3H-didesmethylimipramine and 3H-amitriptyline to brain synaptic plasma membranes (SPM) was studied. Binding of methylated tricyclic antidepressants was more affected. Cocaine inhibits 3H-imipramine binding at concentrations higher than 10(-5) mol/l. Binding stimulated by phosphatidylserine was affected more significantly.

Animals↗

PubMed1991

Methylated and demethylated tricyclic antidepressants and their binding to cell membranes.

We studied the binding of methylated and demethylated tricyclic antidepressants (TCA) to synaptic plasma brain membranes (SPM) and to lymphocyte, platelet and erythrocyte membranes. In the synaptic plasma membranes, more demethylated than methylated dibenzazepine derivatives were bound and the binding affinity was decreased. By contrast, in lymphocyte and platelet membranes more methylated derivatives were bound. Phosphatidylserine (PS) enhanced significantly the binding of methylated TCA in SPM without changing the dissociation constant (Kd). Lysophosphatidylserine did not affect the binding. PS also caused an increase of 3H-imipramine binding to lymphocyte membranes but the binding to platelet membranes was not affected. PS also enhanced 3H-5-HT uptake into platelets and 3H-noradrenaline uptake into lymphocytes.

Animals↗

PubMed1991

Changes of ligand binding after membrane phosphorylation.

Phosphorylation of synaptic plasma brain membranes (SPM) causes a decrease of the specific binding of demethylated tricyclic antidepressants (TCA) and changes the affinity of 3H-imipramine and 3H-desmethylimipramine binding. The decrease of TCA binding was found also in lymphocyte membranes. In platelet membranes a decreased binding was found only with demethylated dibenzazepine derivatives. Bmax and Kd values are also decreased in the presence of phosphatidic acid or alpha-glycerolphosphate.

Animals↗

PubMed1989

[Rapid detection and easy culture of Campylobacter pylori from human gastric mucosa].

96 gastric mucosal biopsy specimens collected at endoscopy and placed into 3 ml 20% glucose were examined histologically, microscopically (Gram staining), by urease test, and by cultivation. The rate of positive findings ws 62.5% by urease test, 34.4% by cultivation, and 27.0% microscopically. By using simple selective solid media, the number of positive cultivations increased to 58.7%. Positive microbiological findings were established by one of three microbiological methods at a high percentage in gastric ulcers (87.5%) and at the lowest rate in duodenal ulcers (57.1%). Remarkable were the positive findings in 60% of patients with normal endoscopic results. In chronic gastritis the highest positivity rate was established histologically (52.6%). Antibiotics without bismuth preparations were used in the treatment of six patients. Check-up examinations yielded negative histological and microbiological findings only in two patients. We failed to affect the inflammatory activity of the gastric mucosa even when consolidation of the ulcer lesion was achieved.

Adolescent↗

PubMed1981