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Biomedical subjects

A Bell

Publications and source records attributed to A Bell.

At least 181 records · Page 10Linked to original sources
PubMed1989

Purification and protein sequence analysis of rat liver prolactin receptor.

Prolactin receptors were purified from rat liver membranes by single-step immunoaffinity chromatography using a specific monoclonal antibody to the rat liver prolactin receptor. Scatchard analysis of 125I-human growth hormone binding to the purified receptor revealed two classes of specific binding sites with Ka = 18.5 x 10(9) and 1.2 x 10(9) M-1. Considering that both classes of binding sites are responsible for high affinity prolactin binding, the partially purified receptor preparation had a binding activity of 1.69 nmol/mg protein, representing 1000-fold purification over microsomal receptors with a recovery of 52%. From three separate purifications, 6 mg of partially purified prolactin receptor were obtained with a purity of approximately 4 to 6.5%. Thus, the use of monoclonal antibody for affinity chromatography resulted in a large improvement of prolactin receptor purification compared to previous hormone affinity chromatography (300-fold purification, 15% recovery). The purified receptor was run on preparative sodium dodecyl sulfate polyacrylamide gel electrophoresis, and a homogeneous preparation of prolactin receptor was obtained by electroelution from gel slices corresponding to Mr 38,000-43,000. Immunoblot analysis using a radiolabeled monoclonal antibody revealed two separate but closely located bands of Mr 42,000 and 40,000 in microsomal, partially purified, and electroeluted preparations. The homogeneous receptor protein was extensively digested with L-1-tosylamido-2-phenylethyl chloromethyl ketone trypsin, and 10 internal amino acid sequences of the rat liver prolactin receptor were determined by gas-phase sequence analysis. Oligonucleotide probes were prepared against two of these internal sequences, and a prolactin receptor cDNA was isolated from a rat liver library using one of these probes (Boutin, J. M., Jolicoeur, C., Okamura, H., Gagnon, J., Edery, M., Shirota, M., Banville, D., Dusanter-Fourt, I., Djiane, J., and Kelly, P. A. (1988) Cell 53, 69-77). The amino acid sequence deduced from the cDNA reveals three potential sites of N-linked glycosylation, two of which were confirmed during protein sequencing. The prolactin receptor was characterized by affinity labeling with 125I-human growth hormone. Cross-linking of microsomes revealed a single band for the hormone-receptor complex with Mr 62,000. On the other hand, cross-linking of Triton X-100-solubilized or partially purified receptor with labeled hormone resulted in the appearance of two bands with Mr 62,000 and 102,000, suggesting the existence of a subunit structure of the prolactin receptor, or alternatively, the existence of two types of prolactin receptor.(ABSTRACT TRUNCATED AT 400 WORDS)

Amino Acid Sequence↗
PubMed1989

Low-level exposures to lead: the Sydney lead study.

The Sydney Lead Study is a prospective investigation of the relationship between low-level lead exposure and neurobehavioural development during the first five years of life. Of the initial cohort of 318 children, 207 remained at the end of the fourth year. Average blood lead levels at 42 and 48 months were 10.7 and 10.1 micrograms/dl, respectively, with only a minority of observations exceeding 15 micrograms/dl. The regression analyses support earlier findings from the study, in that exposure to lead resulting in the range of blood lead levels found in this cohort is not associated with mental or motor deficits in the preschool years.

Adult↗
PubMed1989

Surface characteristics of Pseudomonas aeruginosa grown in a chamber implant model in mice and rats.

Pseudomonas aeruginosa PAO1 was grown in vivo in chambers implanted into the peritoneums of mice and rats. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of extracts of bacterial cells taken from the chambers and washed to remove loosely bound host proteins revealed the presence of the major outer membrane proteins D2, E, F, G, and H2. Western immunoblotting with specific antisera confirmed the presence of porin protein F and lipoprotein H2. However, there was no apparent induction of the phosphate starvation-inducible porin P or the divalent cation starvation-inducible protein H1. Small amounts of proteins with molecular weights similar to those of the iron-regulated outer membrane proteins were found in cells grown in vivo; however, their presence could not be confirmed immunologically. The presence of pili and flagella on the cells grown in vivo was demonstrated by electron microscopy and Western immunoblotting. A consistent alteration in the lipopolysaccharide banding pattern was observed after growth in vivo. Compared with cells of strain PAO1 grown in vitro, cells grown in vivo appeared to lack a series of high-molecular-weight O-antigen-containing lipopolysaccharide bands and gained a new series of lower-molecular-weight lipopolysaccharide bands. This alteration in the lipopolysaccharide after growth in vivo did not affect the O-antigen serotype or the resistance of the bacteria to serum.

Animals↗
PubMed1989

Outer membrane protein H1 of Pseudomonas aeruginosa: purification of the protein and cloning and nucleotide sequence of the gene.

Overexpression of the divalent cation-regulated outer membrane protein H1 of Pseudomonas aeruginosa is associated with resistance to polymyxin B, aminoglycosides, and EDTA. Protein H1 is believed to act by replacing divalent cations at binding sites on lipopolysaccharide, thereby preventing disruption of the sites and subsequent self-promoted uptake of the antibiotics. Protein H1 purified by two cycles of anion-exchange chromatography was apparently associated with lipopolysaccharide. Lipopolysaccharide-free protein H1 was purified in high yield by preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis and was subjected to N-terminal amino sequencing. Complementary oligodeoxyribonucleotides were used to clone the structural gene for protein H1, oprH, into Escherichia coli. Successful cloning was confirmed by nucleotide sequence analysis. Southern hybridization suggested that oprH was present as a single-copy gene in P. aeruginosa. The deduced amino acid sequence revealed that H1 was a slightly basic polypeptide of 178 residues, with a leader sequence typical of an exported procaryotic protein. It had little similarity, however, to other bacterial surface proteins for which sequence data were available. No expression of protein H1, from its own or the lac promoter, was detected in E. coli. We concluded that, as for some other regulated Pseudomonas genes, expression of oprH, at least under some conditions, is blocked in E. coli.

Amino Acid Sequence↗
PubMed1989

I'm not sure what I want, but I want it now.

This title epitomises the demands of theatre staff and the terror of HSDU/ISSU managers. Technological developments, surgeons' whims and variable theatre workloads all suggest that the one essential piece of equipment for both theatre and sterile services managers is a well polished crystal ball.

Central Supply, Hospital↗
PubMed1989

Progressive systemic sclerosis: Part 2--Nursing management.

Multiple body systems can be affected by scleroderma. Satisfactory coping and life-style alterations will depend on numerous factors, including the nature and extent of organ involvement, individual coping style, and health professional services provided. Because of the low incidence of this disease, nurses may have little knowledge about the nursing management. Because of the nature of the disease's complications, the nephrology or dialysis nurse may care for more scleroderma patients than other hospital nurses.

Adaptation, Psychological↗
PubMed1988

Antibiotic uptake into gram-negative bacteria.

Antibiotics taken up into gram-negative bacteria face two major diffusion barriers, the outer and cytoplasmic membranes. Of these, the former has been most studied and is discussed in detail here. Evidence from antibiotic MIC studies on porin-deficient mutants compared with their porin-sufficient parent strains has provided strong support for the proposal that some antibiotics, particularly beta-lactams, pass across the outer membrane through the water-filled channels of a class of proteins called porins. Nevertheless substantial evidence has accumulated for the importance of non-porin pathways of antibiotic uptake across the outer membranes of gram-negative bacteria. Examples discussed include the uptake of polycationic antibiotics via the self-promoted pathway, the uptake of hydrophobic antibiotics in some bacterial species and in mutants of others via the hydrophobic pathway, and the possible importance of poorly understood non-porin pathways of uptake of a variety of antibiotics. Other potential barriers to diffusion, including the cytoplasmic membrane, are briefly discussed.

Anti-Bacterial Agents↗
PubMed1987

Identification of erythro-beta-hydroxyasparagine in the EGF-like domain of human C1r.

Previous studies [(1987) Biochem. J. 241, 711-720] have shown that position 150 of human C1r is occupied by a modified amino acid that, after acid hydrolysis, yields erythro-beta-hydroxyaspartic acid. In view of further investigations on the nature of this residue, peptide CN1a T8/T9 TL8 (positions 147-155) was isolated from C1r A chain by CNBr cleavage followed by enzymatic cleavages by trypsin and thermolysin. Amino acid analysis, sequential Edman degradation and FAB-MS of this peptide indicate that the residue at position 150 is an erythro-beta-hydroxyasparagine resulting from post-translational hydroxylation of asparagine.

Amino Acids↗