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Biomedical subjects

I Jalsenjak

Publications and source records attributed to I Jalsenjak.

At least 19 recordsLinked to original sources
PubMed2000

Chitosan microspheres with hydrocortisone and hydrocortisone-hydroxypropyl-beta-cyclodextrin inclusion complex.

In the present study, an inclusion complex composed of hydrocortisone acetate (HC) and hydroxypropyl-beta-cyclodextrin (HPbetaCD) was prepared by the spray-drying method. HC alone, HC inclusion complex or HC with HPbetaCD as a physical mixture were incorporated into chitosan microspheres by spray-drying. The inclusion complex and microspheres were characterized by X-ray powder diffractometry and differential scanning calorimetry (DSC). Microspheres were studied with respect to particle size distribution, drug content and in vitro drug release. The results indicate that the HCHPbetaCD inclusion complex is more water soluble than HC alone. The HC release rates from chitosan microspheres were influenced by the drug/polymer ratio in the manner that an increase in the release rate was observed when the drug loading was decreased. However, release data from all samples showed significant improvement of the dissolution rate for HC, with 25-40% of the drug being released in the first hour compared with about 5% for pure HC. The complexation method and microsphere preparation method (spray-drying) is simple with great potential for industrial production.

2-Hydroxypropyl-beta-cyclodextrin↗
PubMed1999

Liposomes containing drugs for treatment of vaginal infections.

To develop a novel vaginal delivery system, able to effectively deliver entrapped drugs during an extended period of time at the site of action, liposomes made of phosphatidylcholine were prepared by two different methods, namely the polyol dilution method and the proliposome method. Liposomes containing three commonly applied drugs in the treatment of vaginal infections: clotrimazole, metronidazole and chloramphenicol were tested for in vitro stability (in buffers at pH 4.5 and 5.9 representing pre- and postmenopausal vaginal pH). In situ stability (in the presence of cow vaginal mucosa) showed that after 6 h incubation (at 37 degrees C), liposomes retained more than 40% of originally entrapped clotrimazole, 28% of entrapped metronidazole or 37% of entrapped chloramphenicol. In vitro and in situ stability studies confirmed the applicability of liposomes as a carrier system for vaginal delivery. Even after 24 h of incubation in the presence of vaginal mucosa liposomes retained sufficient amounts of entrapped drugs.

Administration, Intravaginal↗
PubMed1999

Albumin-loaded PLA and PLGA microspheres: in vitro evaluation.

Polylactide (PLA) and poly(lactide-co-glycolide) (PLGA) microspheres containing bovine serum albumin (BSA) as a model protein were prepared by an solvent extraction procedure using water-in oil-in water complex emulsion system. The effects of process parameters on morphology, particle size, protein loading and in vitro release properties of microspheres were studied. The encapsulation efficiency was very high ranging from 75% to 99%. The in vitro release profile was described as bi-phasic process with an initial burst effect and the second sustained release phase and it was dependent on the type of polymer used, and BSA loading of microspheres.

Lactic Acid↗
PubMed1994

Encapsulated genetically engineered fibroblasts: release of nerve growth factor and effects in vivo on recovery of cholinergic markers after devascularizing cortical lesions.

Genetically engineered rat fibroblasts producing nerve growth factor (NGF) were encapsulated in alginate-polylysine-alginate gels with the objective to produce viable "minifactories" continuously producing and secreting NGF into the rat brain. Microencapsulated fibroblasts (NGF secretors and NGF non-secretors) were placed onto the surface of the lesioned rat cortex (unilateral devascularizing lesion) and animals were sacrificed 30 days after surgery. Fibroblasts NGF-non secreters normally produce tumors after implantation, therefore, they were irradiated prior to encapsulation. Three other experimental groups were studied in parallel: non-lesioned (controls), lesioned rats receiving "empty" alginate spheres and lesioned animals without treatment and microspheres. Biochemical analysis of microdissected brain tissues of lesioned animals treated with encapsulated NGF-secretor fibroblasts showed a significant increase in choline acetyltransferase (ChAT) activity in cortices adjacent to the lesion but not far from it (entorhinal cortex). This may indicate a gradient of concentration of the released NGF and/or differential responsivity of lesioned vs non-lesioned target tissue. ChAT enzymatic activity in the microdissected nucleus basalis magnocellularis (NBM) was significantly decreased (P < 0.05) in all lesioned animals treated with spheres without fibroblasts and those with fibroblasts not secreting NGF. Morphometric analysis of ChAT-IR and low affinity NGF-receptor IR cholinergic neurons in the middle portion of the NBM shows a prevention of neuronal shrinkage and extensive neuropil in animals treated with microencapsulated NGF-secretor fibroblasts. The results of this study demonstrate that NGF from encapsulated genetically engineered fibroblasts can be secreted for at least long enough to prevent degenerative changes of cholinergic neurons in the NBM.

Alginates↗
PubMed1993

Microspheres of human serum albumin with barbiturates: effect of drug partition coefficient on preparation and drug release.

Human serum albumin microspheres were prepared with a series of barbiturates by the thermal denaturation method. The barbiturates were of similar general physicochemical properties but different partition coefficients. The total drug content of microspheres was dependent on the partition coefficient, and an increase in the partition coefficient caused a decrease in the drug content of finished microspheres due to drug migration to the outer organic phase during preparation. The ensemble drug release from microspheres was followed by the paddle method and by potentiometric titration with a pH-stat. Nonlinear regression analysis showed the best fit for the spherical Higuchi equation, especially first-order kinetics (biphasic). The drug partition coefficient affected the release in such a way that drugs with higher partition coefficients were released faster and to a greater extent than those with lower coefficients.

Barbiturates↗
PubMed1992

Microencapsulated nerve growth factor: effects on the forebrain neurons following devascularizing cortical lesions.

In this study, we report the effects of nerve growth factor (NGF) delivered into the CNS via a novel delivery system for prolonged, controlled release. The effectiveness of NGF incorporated in the biodegradable microspheres was investigated in the rat model for central cholinergic degeneration. Mature male rats were unilaterally lesioned by disruption of the pia arachnoid vessels and vehicle (alginate microspheres without NGF) and microencapsulated NGF was placed at the site of the lesion. Choline acetyltransferase (ChAT) activity was measured in the nucleus basalis magnocellularis (NBM) and cortex in the (a) non-lesioned control animals; (b) lesioned animals treated with 'empty' microspheres and (c) lesioned animals treated with microspheres containing NGF, 30 days following surgery. Similarly lesioned animals received NGF via permanently installed cannulae in order to compare the novel route of administration with the more conventional one. Immunocytochemical results showed an absence of the cholinergic cell body shrinkage in the NBM otherwise observed in lesioned animals. Furthermore, an increase in intensity of ChAT immunostaining in NGF-treated, lesioned animals was evident. The present results stress the experimental therapeutic possibilities of novel delivery systems for administration of trophic factors in the CNS.

Alginates↗
PubMed1989

Effects of microencapsulated monosialoganglioside GM1 on cholinergic neurons.

The preparation, physical characterization and effects of microcapsules containing the monosialoganglioside GM1 in an in vivo rat model are described herewith. Several preparations of microcapsules were obtained differing in physical and chemical properties. Human serum albumin (HSA) microcapsules with or without GM1 are spherical in shape, have a consistent particle size (8-10 microns in diameter) and are devoid of large pores. In agreement with our previous work, we now provide further evidence that GM1 can prevent shrinkage and the decrease of choline acetyltransferase activity in the nucleus basalis magnocellularis (NBM) of the rat following a unilateral cortical lesion. In the present study we examined the effect of microencapsulated GM1 in this in vivo rat model. Local application of HSA-microencapsulated GM1 (in doses comparable to those obtained by i.c.v. administration) onto the surface of the lesioned cortex prevents both the biochemical and morphological degenerative changes in the NBM of rats with unilateral devascularizing cortical lesions. The results from these studies show that microencapsulated GM1 can be applied successfully and a prolonged controlled release of this drug obtained, thus avoiding surgical implantation of a cannula.

Animals↗
PubMed1985

Flavonoid content in propolis extracts and growth inhibition of Bacillus subtilis.

Thirty eight propolis samples were collected in several regions of SR Croatia differing in climate and vegetation. Amounts of 3,5,7-trihydroxyflavone and of 5,7-dihydroxyflavonone were determined chromatographically in individual propolis samples. Concentrations of each constituent were correlated with the growth inhibitions of Bacillus subtilis (IP-5832).

Bacillus subtilis↗
PubMed1983

Influence of drug partition coefficient and pH value of sink solution on permeation from porous thick-walled ethyl cellulose microcapsules.

The permeation of barbitone sodium, benzoic acid, and salicylic acid from microcapsules into aqueous medium has been examined at different pH values. The apparent diffusion coefficients of drugs were linearly proportional to the ethyl cellulose/water partition coefficient of drugs, and the straight line parameters were dependent upon volume fractions of water-filled pores (i.e. capsule size), testifying to a previously proposed mechanism of drug permeation. The rate of drug permeation was also a function of the pH-value of the surrounding sink solution; the period of zero order release was longer at low pH because of the change of drug partition or solubility or both.

Barbital↗
PubMed1982

Volume of water-filled pores in the ethyl cellulose membrane and the permeability of microcapsules.

The volume fraction of the water-filled pores in the microcapsule membranes was calculated and the values from 0.55 to 2.5% were obtained. Differential scanning calorimetry of aqueous suspensions of microcapsules showed no structured water present in the ethyl cellulose membranes. The temperature effect on the apparent diffusion coefficient of a drug was investigated and the apparent activation energy of diffusion was calculated.

Calorimetry↗
PubMed1982

Growth inhibition of bacillus subtilis and composition of various propolis extracts.

The composition of 31 samples of propolis extract was investigated by using TLC. Ethanol extract of propolis (EEP) prepared from the various propolis samples differ mainly in quantities of identified compounds, and not in kind of components present. According to the inhibitory activity against Bacillus subtilis, the propolis samples were grouped in three categories. It appears that the galangin content in a sample is a main constituent, which determines its antibacterial activity.

Anti-Bacterial Agents↗
PubMed1982

Inhibition of growth and biosynthesis of ochratoxin A in Aspergillus sulphureus NRRL 4077 by propolis extract.

Growth inhibition of Aspergillus sulphureus NRRL 4077 and biosynthesis of ochratoxin A in the presence of propolis was investigated. Although the growth of the micro-organism was inhibited at all concentrations of applied propolis extract up to d 10 of incubation, only the 2.0 mg/ml concentration of propolis exhibited definite fungistatic activity. Ochratoxin A was detected in all culture media, but its amounts were low in the first 10 d of experiment. In comparison with the control culture, the amounts of ochratoxin A were proportional to the growth of A. sulphureus and reciprocal to the amounts of propolis extract used.

Aspergillus↗
PubMed1981

Effect of capsule size on permeability of gelatin-acacia microcapsules toward sodium chloride.

The effect of capsule size on the permeability of gelatin-acacia microcapsules toward sodium chloride was investigated. Gelatin-acacia microcapsules containing olive oil were prepared by phase separation. The encapsulated olive oil was extracted with acetone and the acetone-loaded microcapsules dispersed in acetone were fractionated by a series of mesh screens. The core material of acetone than was replaced by water. The permeability of each capsule fraction toward sodium chloride was estimated from the change in electrical conductance with time of the mixture of microcapsule suspension and sodium chloride solution. The permeability decreased with decreasing capsule size. Structured water in and around the capsule wall may be the cause of the observed size effect.

Capsules↗
PubMed1981

Apparent diffusion coefficient of sodium phenobarbitone in ethylcellulose microcapsules: effects of capsule size.

Ethylcellulose microcapsules of sodium phenobarbitone with a thick wall were prepared and fractionated. The apparent diffusion coefficient of sodium phenobarbitone was measured for the transport of the drug from the core of microcapsules into the surrounding sink condition. The apparent diffusion coefficient decreased with decreasing capsule size. Apart from structured water in and around the capsule wall, the volume fraction of pores in the membrane has been suggested as the source of the observed trend.

Capsules↗
PubMed1980

Sustained-release dosage forms of microencapsulated isoniazid.

The preparation and release characteristics of microcapsules of isoniazid have been studied. The differing techniques of microencapsulation are assessed and the dissolution of drug from suspended and tableted microcapsules prepared using the chosen technique has been monitored for in vitro release.

Capsules↗
PubMed1977

Dissolution from tablets prepared using ethyl cellulose microcapsules.

Microcapsules containing sodium phenobartitone cores in ethyl cellulose have been used to prepare tablets at from 3-9 to 358-9 MPa compression pressures. The tensile strength of these tablets is related linearly to the core: wall ratio and to the microcapsule size. Dissolution of the drug from the microcapsules, is also related to the core:wall ratio and microcapsule size, but except at low compression pressures is almost independent of the pressure used during preparation. The tablet matrix remains intact during the dissolution and the equations developed by Schwartz, Simonelli & Higuchi (1968) are followed. Large microcapsules 1:2 core: wall ratio produce friable tablets with rapid release of contents.

Capsules↗