The influence of gamma irradiation on the physicochemical properties of a novel triblock copolymer of epsilon-caprolactone and ethylene oxide.

A novel triblock copolymer of epsilon-caprolactone (CL) and ethylene oxide (E), CL6E90CL6, intended for use in implantable drug-delivery systems, has been subjected to gamma irradiation, in the solid state and in aqueous solution, under different controlled environmental conditions, to assess its stability to a radiation sterilization process. When copolymer matrices were irradiated with doses of irradiation up to 72 kGy in the presence of oxygen, negligible changes were observed in the molar mass, molecular mobility (assessed by pulsed nuclear magnetic resonance spectroscopy) and thermal properties. However, irradiation of matrices in the absence of oxygen (anoxia) induced the formation of cross-links, as indicated by a reduction in the molecular mobility of the copolymer, but without affecting its molar mass and thermal properties.

Characterization of the influence of some cyclodextrins on the stratum corneum from the hairless mouse.

Differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR) spectroscopy and transmission electron microscopy (TEM) have been used to determine the influence of beta-cyclodextrin (beta-CyD), hydroxypropyl-beta-CyD (HP-beta-CyD) and gamma-CyD on the structural properties of the stratum corneum from the hairless mouse. Some modest changes in the stratum corneum lipid transition temperature were induced by HP-beta-CyD and blue shifts were observed in the FTIR spectra of the C-H asymmetric and symmetric stretching of the lipids from the stratum corneum. Results from TEM studies indicated that HP-beta-CyD caused removal and possible disorganization of the lipid matrix that envelopes the corneocytes of the stratum corneum, whereas no effect was seen after treatment of the samples with beta-CyD and gamma-CyD.

An investigation of the parameters influencing the bioadhesive properties of Myverol 18-99/water gels.

An in vitro assessment was undertaken of the parameters influencing the bioadhesive strength of lyotropic liquid crystalline gels formed by the monoglyceride blend Myverol 18-99 and water. The gels were found to bind more strongly to a dry Perspex surface than to moist mucosal tissue and were shown to be weaker bioadhesives than Carbopol 934P and sodium alginate. The works of adhesion and forces of detachment were independent of contact time, were reduced by the presence of surface water and increased with an increase in the compression force, suggesting that interpenetration was not the mechanism of bioadhesion.

Screening protocol for Torulopsis (Candida) glabrata.

A screening test has been developed for the presumptive identification of Torulopsis (Candida) glabrata from other common clinical isolates of yeast-like fungi. An interlaboratory comparison of a protocol consisting of morphology on cornmeal Tween 80 agar and trehalose fermentation at 42 degrees C was successful in differentiating T. glabrata from other taxa that are frequent or possible clinical isolates.

The in vitro release of some antimuscarinic drugs from monoolein/water lyotropic liquid crystalline gels.

Purpose: To investigate the potential use of a monoolein/water lyotropic liquid crystalline gel for the vaginal delivery of the antimuscarinic drugs, propantheline bromide and oxybutynin hydrochloride to treat urinary incontinence, using Myverol 18-99 as a commercially available grade of monoolein.

Methods: The influence of propantheline bromide and oxybutynin hydrochloride on the phase structure of Myverol 18-99/water gels was investigated using polarising microscopy. The in-vitro release of the antimuscarinic drugs from Myverol 18-99/water gels was determined and the release pattern interpreted with the aid of results from swelling studies and partition coefficient determinations.

The release of 5-fluorouracil from a swellable matrix of a triblock copolymer of epsilon-caprolactone and ethylene oxide.

Purpose: The purpose of this study was to investigate the influence of hydration characteristics on the in vitro release of 5-fluorouracil from a swellable matrix prepared using a novel triblock copolymer of poly(epsilon-caprolactone) and poly(oxyethylene).

Methods: Matrices were prepared by dry compression of mixtures of the drug and copolymer using low compressional forces. Release studies were performed using a custom made rotating basket dissolution apparatus.

Preparation and characterization of poly(epsilon-caprolactone) polymer blends for the delivery of proteins.

A series of ternary blend matrices, based on high- and low-molecular-weight poly(epsilon-caprolactone) (PCL) and a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymer (Synperonic L61), has been developed for the delivery of proteins. The inclusion of Synperonic L61 served to enhance the water content of the matrix available for protein diffusion. Blends comprising high-molecular-weight PCL (PCLH) and Synperonic L61 alone were found by scanning electron microscopy to be incompatible over a wide composition range.

The microencapsulation of protein using a novel ternary blend based on poly(epsilon-caprolactone).

Microspheres with an entrapped protein were prepared from poly(epsilon-caprolactone) (PCL), and a novel ternary blend, comprising of high and low molecular weight PCL in combination with poloxamer 181, a triblock copolymer of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide). The inclusion of low molecular weight PCL served to enhance phase mixing by a reduction in the molecular weight of the polymeric components. Encapsulation of the protein, bovine serum albumin, was possible using a water-in-oil-in-water multiple emulsion solvent evaporation technique.

Solubilisation of drugs in micellar systems studied by eluent gel permeation chromatography.

Purpose: The purpose of the study was to investigate the potential of a chromatographic method which is based on elution gel chromatography (EGPC) in the study of solubilisation of drugs in micellar solutions.

Methods: The EGPC method differs from conventional GPC in the use of a solution of the associating surfactant as eluent (rather than solvent) and the injection of a small volume of solution of different concentration (or alternatively injection of solvent alone) to probe the association equilibrium in the eluent. The technique was applied to a study of the solubilisation of selected drugs in aqueous micellar solutions of a triblock copolymer (Synperonic-PE F127) composed of oxyethylene [E, OCH2CH2] and oxypropylene [P, OCH2CH(CH3)] units with nominal molecular formula E98P67E98.

Treatment of chronic hepatitis C with interferon alpha.

Aim: To evaluate the response to interferon alpha in patients with chronic hepatitis C in Christchurch.

Method: Fifteen patients with chronic HCV were given interferon alpha 3 million units subcutaneously three times a week for up to 24 weeks. A complete and partial biochemical response was defined by relative changes in the serum alanine aminotransferase (ALT) during the treatment period.

Two cases of de novo precursor B-cell acute lymphoblastic leukemia with t(14;18), but without cytogenetic evidence of an associated Burkitt's or Burkitt's variant translocation.

This study reports two cases of acute lymphoblastic leukemia of precursor B-cell type. The cases were associated with a t(14;18), but no evidence of a Burkitt's-type translocation was found. There was also no evidence of a preexisting follicular lymphoma.

Alternative splicing of a neural-specific Src mRNA (Src+) is a rapid and protein synthesis-independent response to neural induction in Xenopus laevis.

Alternative splicing is used by the src protooncogene to derive two gene products, pp60c-src and pp60+. pp60+ is expressed exclusively in neurons, whereas pp60c-src is expressed in many tissues. The specific role of the src+ gene product in neurons is not yet understood.

Identification and developmental expression of Src+ mRNAs in Xenopus laevis.

Alternative splicing of src mRNA has been demonstrated in several vertebrate species to yield a neuron-specific form of src protein termed pp60+. The function of pp60+ is unknown. The early developmental expression pattern of src+ RNA has not been previously examined.

The risk of infection from Giardia lamblia due to drinking water supply, use of water, and latrines among preschool children in rural Lesotho.

Stool samples were collected from 267 rural, preschool children in four districts in Lesotho during October-November, 1984. Sixty-three children (23.6%) were tested positive for Giardia lamblia, the most commonly recovered parasite from stool samples.

The yes proto-oncogene is present in amphibians and contributes to the maternal RNA pool in the oocyte.

Low stringency screening of a cDNA library from the frog Xenopus laevis with a viral yes oncogene probe resulted in the isolation of clones with restriction maps which were distinct from previously identified X. laevis src cDNA clones. The polypeptide produced by in vitro translation of RNA synthesized from one of the clones was slightly larger in size than X.

The influence of a block copolymer on the efficiency of interfacial microencapsulation.

Both the presence of poloxamer in concentrations from 1 to 100 per cent w/v and variation in non-aqueous phase ratio in the range 0.2 to 2.0 influence the extent to which acetanilide is incorporated into piperazine arabate microcapsules compared to acetanilide encapsulation without polymer.

The influence of the ammonium ion on the stability of ethacrynic acid in aqueous solution.

Investigations by reversed-phase HPLC into the stability of ethacrynic acid in buffered aqueous solutions containing either sodium or ammonium ions showed that the extent of degradation was influenced both by the species and concentration of the cation. A reported incompatibility between ethacrynic acid and the ammonium ion, attributed to the influence of the ammonium ion on an equilibrium existing between ethacrynic acid and one of its known degradation products, was shown to be due to the generation of an additional degradation product in ammonium-containing solutions only. This product was isolated and identified.

Perinatal mortality in Southland: an ongoing review.

A review of Southland's perinatal mortality was undertaken from 1978 to 1983 and included 124 deaths with a postmortem rate of 90%. The perinatal mortality rate has continued to fall during this period, and has more than halved since 1971. Prematurity remains the single most important factor, and there are still a large number of avoidable deaths.