Poly(lactide-co-glycolide) nanoparticles loaded with pilocarpine hydrochloride were prepared by the high-pressure emulsification-solvent evaporation method. The nanoparticles were produced using polyvinylalcohol (PVA), carbomer (Carbopol 980) or poloxamer (Lutrol F-68) as stabilizers during emulsification. The influence of pressure and number of cycles on the nanoparticle properties was investigated. For comparison, nanoparicles without high-pressure treatment of the emulsion were made. The nanoparticle size, drug loading and release properties depended strongly on the homogenization pressure and number of cycles applied. Nanoparticles obtained without high pressure homogenization showed larger size and high values of polydispersity index, especially when carbopol and poloxamer were used as emulsifiers. Drug loading and encapsulation efficiency of all samples also decreased with pressure. The low drug loading could be due to two reasons. First, the high pressure promoted drug diffusion out of protoparticles during emulsification either by size reduction or shear forces. Secondly, the characteristics of the outer water phase of the emulsion also influenced the nanoparticle drug loading. This was proven by the different drug loadings measured when nanoparticles were made with PVA, carbopol or poloxamer at equal pressures applied. The main factor influencing the release properties of nanoparticles was the pressure used during emulsification. Faster drug release was observed from nanoparticles obtained after high-pressure emulsification compared to those prepared without homogenization of the emulsion.

Acrylic Resins↗

PubMedDate not supplied

Characterization of Sox9 in European Atlantic sturgeon (Acipenser sturio).

The Sox9 gene of Acipenser sturio, one of the most primitive vertebrates, was analyzed. No sex-specific differences were observed. Sturgeon Sox9 consists of three exons and two introns with completely conserved exon-intron boundaries showing high levels of homology to other vertebrate Sox9 sequences, especially in the N-terminus region containing the HMG box. We found strong evidence for negative (purifying) selection. In contrast to previous studies of other fishes, we observed no evidence for gene duplication in sturgeon. Phylogenetic analyses of Sox9 evolution revealed a basal position for sturgeon Sox9.

Amino Acid Sequence↗

PubMedDate not supplied

Differential distribution of four hyperpolarization-activated cation channels in mouse brain.

Hyperpolarization-activated cation currents, termed I(h), are observed in a variety of neurons. Four members of a gene family encoding hyperpolarization-activated cyclic-nucleotide-gated cation channels (HCN1-4) have been cloned. The regional expression and cellular localization of the four HCN channel types in mouse brain was investigated using in situ hybridization. The expression of HCN1 was restricted to the olfactory bulb, cerebral cortex, hippocampus, superior colliculus and cerebellum. In contrast, HCN2 transcripts were found at high levels nearly ubiquitously in the brain, and the strongest signals were seen in the olfactory bulb, hippocampus, thalamus and brain stem. HCN3 was uniformly expressed at very low levels throughout the brain. Finally, HCN4 transcripts were prominently expressed selectively in the thalamus and olfactory bulb. Some neurons expressed two or more HCN channel transcripts including hippocampal pyramidal neurons (HCN1, HCN2 and low levels of HCN 4) and thalamic relay neurons (HCN2 and HCN4). Our results demonstrate that each HCN channel transcript has a unique distribution in the brain. Furthermore, they suggest that the heterogeneity of neuronal I(h) may be, at least in part, due to the differential expression of HCN channel genes.

Amino Acid Sequence↗

PubMedDate not supplied

Evaluation of pilocarpine loaded gelatin particles for topical ophthalmic use.

Gelatin particles containing pilocarpine HCl were prepared using a desolvation method. The influence of the gelatin type and the preparation pH on particle properties was studied. The drug entrapment amounted 44 to 57%, zetapotential was slightly negative. Particle size varied from 312 nm to 500 nm depending on preparation pH. Franz diffusion cell experiments showed a release approaching zero-order kinetics and a sustained release compared to an aqueous pilocarpine HCl solution.

Excipients↗

PubMedDate not supplied

Influence of the physicochemical properties and concentration of native and modified potato starch on the release of a hydrophobic drug from hard gelatin capsules.

The influence of the physicochemical properties and concentration of potato starch and sodium starch glycolate on the release of phenacetin from hard gelatin capsules is examined. Smaller quantities of sodium starch glycolate are necessary to improve the disintegration of the encapsulated powder mass and the drug release, compared to blends with potato starch. From the ratio of the absolute particle diameter increase to the mean pore diameter of the encapsulated powder mass no prediction about capsule disintegration could be made, contrary to tablets. A better correlation seems to exist between the total volume increase of the starch grains and the disintegration time of the formulation.

Capsules↗

PubMedDate not supplied

Evaluation of sodium hyaluronate as viscous vehicle for eye drops.

The influence of sodium hyaluronate and hydroxyethylcellulose on the elimination of a fluorescent tracer from the precorneal area of human eyes is investigated using a slit lamp fluorophotometer. The rheological characteristics of the equiviscous ophthalmic solutions are examined. Both viscosity enhancing polymers improve significantly the residence of the tracer in the tear film. The high viscous sodium hyaluronate solution is better tolerated than the hydroxyethylcellulose solution.

Chemistry, Pharmaceutical↗

PubMedDate not supplied

Influence of the surface tension of eye drops on the retention of a tracer in the precorneal area of human eyes.

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Conjunctiva↗