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Biomedical subjects

S G Frank

Publications and source records attributed to S G Frank.

8 recordsLinked to original sources
PubMed1990

Ocular toxicity of vitreal pluronic polyol F-127.

To evaluate pluronic polyol F-127 (PF-127) as a vitreous substitute and an intraocular drug delivery system, a total vitrectomy was performed on 18 New Zealand rabbits (18 eyes). The vitreous was replaced with either PF-127 (9 eyes) or balanced salt solution (9 eyes). There was little difference clinically between the eyes containing PF-127 and the control eyes. Both groups showed mild postoperative inflammation, with no differences in intraocular pressures. Histopathologic findings for the control group showed no significant retinal alteration, and serial ERG findings were within normal limits. In contrast, the eyes containing PF-127 showed marked destruction of the retina by 2 weeks after surgery. The ERG amplitudes decreased dramatically to a flat tracing by 24 hours after surgery. Although it is attractive as a potential vitreous substitute, PF-127 is not safe for human use, at least at the concentration used.

Animals↗
PubMed1978

Phase solubility analysis and PMR study of complexing behavior of dinoprostone with beta-cyclodextrin in water.

The mechanism of inclusion compound formation by dinoprostone (prostaglandin E2) with beta-cyclodextrin was studied by phase solubility analysis and PMR spectroscopy. As indicated by the linear increase of aqueous solubility of dinoprostone with beta-cyclodextrin concentration, some types of molecular interactions definitely exist between dinoprostone and the complexing ligands. The temperature dependence of a 1:1 complex formation constant yielded the following thermodynamic data at 20 degrees : deltaG degrees = -4.11 kcal/mole, deltaH degrees = 7.20 kcal/mole, and deltaS degrees = 10.5 e.u. Since water was the solvent system, these parameters appear to be largely determined by solvent reorganization through hydrogen bonding rather than solely by the binding of desolvated free dinoprostone and beta-cyclodextrin entities. PMR data indicate that dinoprostone is included within the cavity and also interacts with protons on the exterior of the beta-cyclodextrin molecule. A model consisting of a 1:1 complex, in which a dinoprostone molecule is partially included within the cavity and the remainder of the molecule extends around the edge of the opening of the cavity to the exterior of the beta-cyclodextrin molecule, is proposed as the most probable structure of this inclusion compound.

Chemical Phenomena↗
PubMed1976

Tritiated naltrexone binding in plasma from several species and tissue distribution in mice.

The binding of 15,16,-3H-naltrexone in human, monkey, dog, guinea pig, rat, and mouse plasma was investigated over a range of concentrations, including predicted therapeutic levels. Studies using equilibrium dialysis at 37 degrees indicate that the extent of binding is independent of naltrexone concentration over the concentration range of 1-500 ng/ml for dog plasma and of 0.1-500 ng/ml for human, monkey, guinea pig, rat, and mouse plasma. The extent of naltrexone binding in plasma is similar in the six species studied, the range being from 20% bound in rat plasma to 26% in plasma from beagle and mongrel dogs. This relatively low extent of naltrexone binding in plasma is consistent with previous findings of a large apparent volume of distribution of this drug in the dog. To investigate further the distribution of tritiated naltrexone, the tissue levels of radioactivity in mice at 1, 5, and 15 min after intravenous administration of 8-3H-naltrexone were determined. Naltrexone was rapidly distributed from plasma to tissues, with less than 4% of the dose being present in plasma at 1 min after injection.

Animals↗
PubMed1975

Metabolic reduction of naltrexone. I. Synthesis, separation and characterization of naloxone and naltrexone reduction products and qualitative assay of urine and bile following administration of naltrexone, alpha-naltrexol, or beta-naltrexol.

Reduction of naltrexone and naloxone with sodium borohydride gave a mixture (85:15) of the 6alpha- and 6beta-hydroxy epimers, alpha- and beta-naltrexol and alpha- and beta-naloxol, respectively. Each pair of epimers was separated by preparative thin-layer chromatography and the physical and spectral properties of each compound were determined. Previous assignments for the configuration of the epimers were verified. A semi-quantitative electron capture gas-liquid chromatographic method was devised for distinguishing either alpha- or beta-naltrexol in the presence of the other and in the presence of large amounts (at least 10-fold greater) of naltrexone. The method was used to determine the approximate weight ratio of beta-naltrexol to naltrexone present in enzymatically hydrolyzed urine samples. It was found that substantially greater quantities of beta-naltrexol and/or its conjugates were excreted in the urine of man, monkey, guinea pig and rabbit after administration of naltrexone, whereas very small quantities were excreted by the mouse, rat and dog. In contrast, just trace amounts of the 6alpha-hydroxy epimer, alpha-naltrexol, were detected in the urine of only 2 of the 7 species that had received naltrexone, i.e., monkey and guinea pig. After administration of 3H-15,16-naltrexone, 1 mg/kg, i.v. to the guinea pig, 25% of the radioactivity found following thin-layer chromatography of the extract of acid-hydrolyzed urine corresponded to beta-naltrexol. In gall bladder bile from the guinea pig, only conjugates of naltrexone and beta-naltrexol were found 2 hours after administration of naltrexone. Following administration of beta-naltrexol, 1 mg/kg, i.v. to guinea pigs only beta-naltrexol and/or its conjugates were detected in urine or bile. However, urine collected after administration of alpha-naltrexol, 1 mg/kg, i.v. to guinea pigs contained alpha-naltrexol and its conjugates, as well as a yet unidentified metabolite.

Animals↗