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What is it "dry eye" and how to treat it?

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Suche zapalenie spojówek i rogówki u zwierząt (KCS) powstaje na skutek zubożonej produkcji łez, co skutkuje ich niedoborem. Choroba objawia się wysuszeniem powierzchni oka. Oko jest zaczerwienione, zwierzę odczuwa świąd. Pojawiają się na powierzchni rogówki keratopatie. Schorzenie występuje u psów, kotów a nawet koni. W miarę trwania choroby, wokół oczu na powierzchni powiek, odkłada się ropna wydzielina. Istnieje wiele przyczyn powodujących taki stan. Głównie są to zaburzenia natury immunologicznej, wady wrodzone, urazy, reakcje polekowe, infekcje wirusowe oraz zaburzenia hormonalne. Rozpoznanie choroby odbywa się za pomocą testu łzowego Schirmera (STT). Leczenie polega na podawaniu preparatów nawilżających oko oraz leków stymulujących produkcję łez (cyclosporyna A, tacrolimus). W przypadku, gdy leczenie takie nie przynosi oczekiwanych rezultatów, można zastosować zabieg transpozycji przewodu ślinianki.
The discovery of cyclosporine A was a milestone in organ transplantation and the treatment of autoimmune diseases. However, developing an efficient oral delivery system for this drug is complicated by its poor biopharmaceutical characteristics (low solubility and permeability) and the need to carefully monitor its levels in the blood. Current research is exploring various approaches, including those based on emulsions, microspheres, nanoparticles, and liposomes. Although progress has been made, none of the formulations is flawless. This review is a brief description of the main pharmaceutical systems and devices that have been described for the oral delivery of cyclosporine A in the context of the physicochemical properties of the drug and the character of its interactions with lipid membranes.
The aim of this study was to compare the most commonly-used experimental models and to assess the microscopic renal changes in different models of cyclosporine A (CsA) nephrotoxicity. Wistar male rats were divided into five groups, eight animals in each. CsA was given in doses of 15 mg/kg, 25 mg/kg, and 100 mg/kg, respectively. The blood was collected for creatinine, urea, and uric acid levels analysis in the serum and the kidneys were sampled for microscopic examination on the 11th and 29th d of the experiment. CsA induced nephrotoxicity was characterised by increased serum levels of creatinine, urea, and uric acid. Microscopic features of CsA nephrotoxicity in all CsA experimental groups were observed. We would recommend the use of low doses of CsA for approximately 28 d as the most relevant experimental procedure for achieving the features of chronic CsA nephrotoxicity.
Cyclosporin A and tacrolimus are powerful immunosuppressants used as post-operation medication after allogenic transplantations. Unfortunately, the drugs Sandimmune (cyclosporin A) and Prograf (tacrolimus) exhibit negative side effects. These side effects may be linked not only to the active ingredients themselves, but also to the vehicle used for their delivery – Cremophor EL and/or ethanol. Sandimmune, Prograf, ethanol, Cremophor EL or Cremophor EL with ethanol (i.e. the complete vehicle) in a saline solution were administered to male Wistar rats either on 6th and 7th or 30th and 31st day postnatally. The functional changes in the nervous system elicited by these substances were assessed by observing the intensity of seizures induced by a single i.p. injection of pilocarpine at 60th postnatal day. Brain anatomy was also analyzed by comparing brain mass, lateral ventricle relative area, thickness of cerebral hemisphere wall, relative size of the hippocampus as well as total density of cresyl violet-stained neurons in the cerebral hemisphere walls between control and experimental animals. Our data point to a significant effect of all tested substances on central nervous system development. The greatest effects on seizure severity and brain structure were associated with the complete vehicle. Such effects (although less sever) were also observed for Cremophor EL and ethanol given separately.
Liposomal formulations of cyclosporin A have been investigated in a series of studies. One of the most used arguments for the development of this pharmaceutical preparation was the high lipophilicity of cyclosporin A, which ensures an encapsulation of cyclosporin A in the liposomal bilayer. From this study on the interaction of cyclosporin with lipids spread as a monolayer on the air/water interface we demonstrate, that one molecule of cyclosporin A occupies an area of 260 Å2 in the lipid monolayer. These data correlate well with molecular modelling data, calculating a cross-sectional area of 230 Å2 for a cyclosporin A molecule. Calculation of a partition coefficient using these data at different surface pressures results in a value of about 4000 at a surface pressure of about 31 mN/m. This partition coefficient is also found in bilayer membranes supporting the notion, that phospholipid bilayer systems have a surface pressure of about 32 mN/m. If the lipid:cyclosporin A ratio exceeds a value of 20, the lipid monolayer becomes nonlinear. Cyclosporin A starts to detoriate liposomal membranes at similar lipid:cyclosporin ratios. It could also be concluded from our measurements at the air/water interface, that cyclosporin A is able to exchange binding places between membranes rapidly with a time constant of about 2.5 min. Lipid monolayer experiments are not only an easy and fast method to obtain information about molecule interactions with lipid membranes, but is also a suitable method to develop liposomal formulations of drugs.
In order to evaluate the role and influence of the methionine residue on the biologi­cal activity of cyclolinopeptide B, an analogue with methionine residue in position 7 replaced by the amphiphilic (S)-a-hydroxymethylmethionine residue was synthe­sized. This peptide exhibits high immunosuppressive activity in the cellular, and to a lesser degree in the humoral immune response, comparable to that of CsA. In addi­tion, the peptide was devoid of toxicity, even at high doses.
Studies were undertaken to evaluate by parasitological techniques the course of intestinal and muscular invasions in mice infected with Trichinella spiralis and treated with TFX-Thymomodulin (TFX-Th). Studies were conducted on 120 mice of BALB/c and SWISS strains, infected each with a mean invasive dose of 300 T. spiralis larvae. TFX-Th (Thymoorgan GmbH Pharmazie Co. KG, Vienenburg, Germany) was administered subcutaneously at 30 mg/kg body weight. Depending upon duration of TFX-Th administration and stages of intestinal and muscular invasions, three experiments were distinguished in the study. The results indicated that TFX-Th promoted eradication of larvae from muscles, whether administered at the early of the late stage of T. spiralis invasion.
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