Amphiphilic cationic peptides mediate cell adhesion to plastic surfaces

Four amphiphilic peptides, each with net charges of +2 or more at neutrality and molecular weights under 4 kilodaltons, were found to mediate the adhesion of normal rat kidney fibroblasts to polystyrene surfaces. Two of these peptides, a model for calcitonin (peptide 1, MCT) and melittin (peptide 2, MEL), form amphiphilic alpha-helical structures at aqueous/nonpolar interfaces. The other two, a luteinizing hormone-releasing hormone model (peptide 3, LHM) and a platelet factor model (peptide 4, MPF) form beta-strand structures in amphiphilic environments. Although it contains only 10 residues, LHM mediated adhesion to surfaces coated with solutions containing as little as 10 pmoles/ml of peptide. All four of these peptides were capable of forming monolayers at air-buffer interfaces with collapse pressures greater than 20 dynes/cm. None of these four peptides contains the tetrapeptide sequence Arg-Gly-Asp-Ser, which has been associated with fibronectin-mediated cell adhesion. Ten polypeptides that also lacked the sequence Arg-Gly-Asp-Ser but were nonamphiphilic and/or had net charges less than +2 at neutrality were all incapable of mediating cell adhesion (Pierschbacher and Ruoslahti, 1984). The morphologies of NRK cells spread on polystyrene coated with peptide LHM resemble the morphologies on fibronectin-coated surfaces, whereas cells spread on surfaces coated with MCT or MEL exhibit strikingly different morphologies. The adhesiveness of MCT, MEL, LHM, and MPF implies that many amphiphilic cationic peptides could prove useful as well defined adhesive substrata for cell culture and for studies of the mechanism of cell adhesion.     

Measures of Quality of Care for People with HIV: A Scoping Review of Performance Indicators for Primary Care

The healthcare of people with HIV is transitioning from specialty care to the primary healthcare (PHC) system. However, many of the performance indicators used to measure the quality of HIV care pre-date this transition. The goal of this work was to examine how existing HIV care performance indicators measure the comprehensive and longitudinal care offered in a PHC setting. A scoping review consisting of peer-reviewed and grey literature searches was performed. Two reviewers evaluated study eligibility and indicators in documents meeting inclusion criteria were extracted into a database. Indicators were matched to a PHC performance measurement framework to determine their applicability for evaluating quality of care in the PHC setting. The literature search identified 221 publications, of which 47 met inclusion criteria. 1184 indicators were extracted and removal of duplicates left 558 unique indicators. A majority of the 558 indicators fell under the ‘secondary prevention’ (12%) and ‘care of chronic conditions’ (33%) domains when indicators were matched to the PHC performance framework. Despite the imbalance, nearly all performance domains in the PHC framework were populated by at least one indicator with significant concentrations in domains such as patient-provider relationship, patient satisfaction, population and community characteristics, and access to care. Existing performance frameworks for the care of people with HIV provide a comprehensive set of indicators that align well with a PHC performance framework. Nonetheless, some important elements of care, such as patient-reported outcomes, are poorly covered by existing indicators. Advancing our understanding of how the experience of care for people with HIV is impacted by changes in health services delivery, specifically more care within the PHC system, will require performance indicators to capture this aspect of HIV care.     

Association of beta-glucosidase with intact cells of Thermoactinomyces.

The location of the B-glucosidase activity in a whole culture broth of the thermophilic organism Thermoactinomyces has been studied. Little beta-glucosidase activity was found in the culture filtrate, while the culture solids contained the major part of the activity of the whole culture broth. The activity does not appear to be adsorbed to the culture solids; rather there is evidence that it is an intracellular soluble enzyme(s). The pH and temperature optima for a crude beta-glucosidase preparation were determined to be pH 6.5 and 50--55 degrees C. Enzyme activity studies indicate that the same enzyme(s) accounts for the beta-glucosidase and the cellobiase activities. The validity of using the filter paper activity of culture filtrates from Thermoactinomyces to predict the total saccharification of cellulosic materials to glucose is discussed.     

Lithium Selectively Inhibits Muscarinic Receptor-Stimulated Inositol Tetrakisphosphate Accumulation in Mouse Cerebral Cortex Slices

The in vitro effects of Li on agonist- and depolarization-stimulated accumulation of inositol phosphates were determined in mouse cerebral cortex slices. Of the agents examined, only the cholinergic agonist carbachol produced a significant accumulation of inositol tetrakisphosphate (InsP4) in the absence of Li. Lithium at 5 mM enhanced the accumulation of inositol monophosphate (InsP1) and inositol bisphosphate (InsP2) due to all the stimuli used and potentiated inositol trisphosphate (InsP3) accumulation due to histamine and noradrenaline, although at lower Li concentrations, carbachol-stimulated InsP3 accumulation was reduced. Li also enhanced InsP4 accumulation in the presence of noradrenaline, histamine, and elevated KCl level but, in marked contrast, reduced carbachol-stimulated InsP4 accumulation with an IC50 of 100 microM. There was a significant time delay between the initiation of carbachol stimulation and the beginning of the InsP4 inhibition due to Li. The phorbol ester 4 beta-phorbol 12 beta-myristate 13 alpha-acetate did not mimic the effects of Li. The results suggest that muscarinic receptor-mediated InsP4 production might be one of the targets for the therapeutic action of Li.     

Depletion and release of prolactin from rat pituitaries and pituitary tumors in vitro

Depletion of pituitary prolactin (PRL) and PRL release into culture medium were simultaneously examined over a 3.5- to 4.0-hr incubation period from anterior pituitary fragments obtained from Fischer-344 or Wistar-Furth female rats treated with estrogen for 5 days, in pituitary tumors induced by 8 weeks of diethylstilbestrol (DES) treatment in Fischer-344 rats and in MtTW15 pituitary tumors transplanted subcutaneously in Wistar-Furth rats for 4 weeks. Our objective was to determine if the event known as transformation, which we define as a loss in the tissue PRL content without a corresponding and equivalent increase in the medium PRL content, occurs in rat pituitary tumors. Our results indicated that transformation did not occur in vitro in rat anterior pituitary tumors induced in Fischer-344 rats by DES treatment but was present in pituitaries from Fischer-344 rats treated for 5 days with estrogen, which served as controls. We also observed in vitro transformation in the anterior pituitary of Wistar-Furth rats treated with estrogen for 5 days (controls) and in the pituitaries of Wistar-Furth rats inoculated with the MtTW15 tumor for 4 weeks, but not in the MtTW15 tumor itself. Although transformation was present in both Fischer-344 and Wistar-Furth rats treated acutely with estrogen the timing of the transformation was delayed 1-2 hr in the Fischer-344 rats compared with Wistar-Furth females. We concluded that transformation does not precede release of prolactin in rat pituitary tumors and that in normal pituitaries the mechanisms of transformation are induced differently between the strains of rats examined.     

Complete nucleotide sequence of the Streptomyces lividans plasmid pIJ101 and correlation of the sequence with genetic properties.

The complete nucleotide sequence of the multicopy Streptomyces plasmid pIJ101 has been determined and correlated with previously published genetic data. The circular DNA molecule is 8,830 nucleotides in length and has a G+C composition of 72.98%. The use of a computer program, FRAME, enabled identification in the sequence of seven open reading frames, four of which, tra (621 amino acids [aa]), spdA (146 aa), spdB (274 aa), and kilB (177 aa), appear to be genes involved in plasmid transfer. At least two of the above genes are predicted to be transcribed by known promoters that are regulated in trans by the products of the korA (241 aa) and korB (80 aa) loci on the plasmid. The segment of the plasmid capable of autonomous replication contains one large open reading frame (rep; 450 aa) and a noncoding region presumed to be the origin of replication. Four other small (less than 90 aa) open reading frames are also present on the plasmid, although no function can be attributed to them. The sequence of the pIJ101 replication segment present in several widely used cloning vectors (e.g., pIJ350 and pIJ702) has also been determined, so that the complete nucleotide sequences of these vectors are now known.