Isolation of a non-sedimenting membrane fraction from the water soluble fraction of bovine lens

A membrane fraction was isolated from the water soluble fraction of bovine lens by increasing the density of the water soluble fraction with KBr and subjecting it to overnight centrifugation at 100000 g. We have called this fraction, which floats to the top of the mixture upon centrifugation, the non-sedimenting membrane fraction (NSMF). Electron microscopy of the NSMF revealed that it is composed of the expected membrane structures of unit membrane, fiber junction and cytoskeleton. Significantly less of the total membrane of the NSMF was devoted to fiber junction (22.8%) than in the sedimenting membrane fraction (SMF) (41.1%) prepared by sucrose density centrifugation of the water insoluble fraction. The NSMF accounted for about 7-12% of the total bovine lens membrane, and preliminary experiments demonstrated that a similar fraction could be isolated from the water soluble fraction of lenses from rats, rabbits, chickens and humans. The NSMF contained about 0.9 mg total lipid per mg total membrane protein, which was significantly greater than the value obtained for the SMF (0.5 mg total lipid per mg total membrane protein). The greater relative amount of total lipid in the NSMF was due to a significantly greater relative amount of phospholipid in the NSMF which was further reflected by the observation that the cholesterol: phospholipid molar ration of the NSMF (0.58) was significantly less than that of the SMF (0.88). Thus the relative lipid composition of the NSMF was significantly different than that of the SMF. Although the phospholipid content of the NSMF was greater than that of the SMF, the compositions of the phospholipids in the two membrane fractions were similar. The NSMF possessed essentially the same polypeptides (both extrinsic and intrinsic) which were found in the SMF. The NSMF was found to be distributed throughout the lens in a proportionate manner. We conclude that the NSMF may account for most of the lipid which remains in the water soluble fraction of the normal bovine lens after sedimentation of the water insoluble fraction. This membrane fraction substantially differs from the SMF in terms of structure and relative lipid composition. We speculate that the NSMF may represent a specialised domain of the fiber cell plasma membrane which has been previously unrecognized.     

Topographic variation in biglycan and decorin synthesis by articular cartilage in the early stages of osteoarthritis: an experimental study in sheep

From October 1988 to January 1992, nine isolates of Pseudomonas aeruginosa carrying transferable plasmids encoding imipenem-hydrolyzing beta-lactamase (pI = c. 9.5) were recovered from nine different patients in a neurosurgical ward of a hospital in Japan. The beta-lactamase activities of the sonicated extracts from the transconjugants were inhibited by EDTA and this was partially reversible by the addition of zinc cation. The substrate specificity and pI of the beta-lactamase were similar to those of the metallo beta-lactamases from P. aeruginosa and Serratia marcescens TN9106. All strains were resistant to imipenem, carbenicillin and antipseudomonal cephems including ceftazidime, cefsulodin, cefpirome, while four and five strains were susceptible to piperacillin and aztreonam, respectively. Both low level imipenem resistance and high level cephem resistance were co-transferred with the production of metallo beta-lactamase, while resistance to piperacillin, aztreonam, and high level imipenem-resistance were not selected. Production of chromosomal cephalosporinase in piperacillin resistant strains was derepressed, and production of outer membrane protein of D2 was diminished in highly imipenem resistant strains. Six strains were isolated in 1991, and the amounts of antipseudomonal agents, especially imipenem, used in the neurosurgical ward increased markedly in this year. Only three of the nine isolates had the same serotype, pyocin type and phage type. Our results suggest that the repeated isolation of imipenem and cephem-resistant P. aeruginosa producing metallo beta-lactamase was related to the high usage of antipseudomonal beta-lactam antibiotics such as imipenem, and was exacerbated by the dissemination of a plasmid.     

Tuberculous meningitis: a 30-year review

Tuberculous meningitis remains an important illness that can be difficult to diagnose in a timely fashion and carries significant morbidity. We present a retrospective review of the cases of tuberculous meningitis diagnosed and treated at a single institution. Fifty-eight cases were identified and stratified according to stage of disease at presentation. Four patients (7%) died; three (5%) developed severe neurological sequelae. Poor outcomes were largely confined to cases presenting in an advanced stage and at the extremes of age. Corticosteroids were administered to 56 patients and may have contributed to the comparatively good outcome in these cases.     

Protein adsorption onto poly(ether urethane ureas) containing Methacrol 2138F: a surface-active amphiphilic additive

Surface characterization and protein adsorption studies were carried out on a series of additive dispersed and additive coated poly(ether urethane ureas), PEUUs, to characterize early events in the blood compatibility of these materials. A hypothesis that is based on surface hydrophilicity, surface flexibility, and adsorption media has been developed to understand the modulated adsorption of plasma proteins by PEUU additives. Electron spectroscopy for chemical analysis (ESCA) and contact angle analysis were performed on two PEUU formulation as well as on PEUU formulations modified with Methacrol 2138F (co[diisopropylaminoethyl methacrylate (DIPAM)/decyl methacrylate (DM)][3/1]) or acrylate or methacrylate polymer or copolymer analogs of Methacrol 2138F. Methacrol 2138F is a commercially used amphiphilic copolymethacrylate. ESCA showed that the PEUUs loaded with Methacrol 2138F or with its hydrophilic component, homopoly (DIPAM) (h-(DIPAM)), had a higher percentage of nitrogen at their surfaces than did the base PEUUs. Contact angle analysis also showed that the air side of PEUU formulations loaded with Methacrol 2138F were more hydrophobic than was the air side of base PEUUs when films were cast from dimethylacetamide. However, during contact angle testing, the air side of PEUU films loaded with Methacrol 2138F rapidly became more hydrophilic than did the air side of the base PEUU films. A radioimmunoassay and whole or diluted human plasma were also used to characterize the presence of the proteins fibrinogen, immunoglobulin G, factor VIII/von Willebrand factor, Hageman factor (factor XII), and albumin, on the surface of the same PEUUs as analyzed by ESCA and contact angle. The protein adsorption assay showed that PEUU films loaded or coated with Methacrol 2138F, with a copolyacrylate analog of Methacrol 2138F (co(diisopropylaminoethyl acrylate [DIPAA]/decyl acrylate [DA]) [3/1]), or with the hydrophilic polyacrylate or polymethacrylate component analogs of Methacrol 2138F (h-DIPAM or h-DIPAA) adsorbed significantly lower amounts of the proteins than did either the base PEUU formulations or the homopoly(decyl methacrylate) (h-DM) or homopoly(decyl acrylate) (h-DA) coated or loaded PEUUs.     

Dyspnea resulting from phrenic nerve paralysis after interscalene brachial plexus block in an obese male--a case report

While current psychiatric taxonomies recognise a classification of amphetamine dependence, derived from the notion of an alcohol dependence syndrome, little research has validated that such a condition exists for this drug. Current amphetamine users (N = 331), were interviewed using the World Health Organization operationalisation of DSM-III-R substance dependence criteria, and a measure of the psychological components of dependence. Structural analyses indicated that a unidimensional dependence syndrome as assessed by DSM-III-R and DSM-IV criteria exists for amphetamine, and that physiological, psychological and behavioural indicators were all important in accounting for the variance in responses. It was demonstrated that the concept of a dependence syndrome is applicable to amphetamine, and that the inclusion of the amphetamine dependence syndrome in DSM-III-R and DSM-IV is valid.