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Biomedical subjects

R Sutherland

Publications and source records attributed to R Sutherland.

At least 73 records · Page 4Linked to original sources
PubMed1982

Distribution of amoxicillin and clavulanic acid in infected animals and efficacy against experimental infections.

The therapeutic effects produced by formulations of amoxicillin plus clavulanic acid (BRL 25 000A and BRL 25 000G) were compared with those of amoxicillin and clavulanic acid separately against a variety of infections produced by amoxicillin-susceptible and beta-lactamase-producing (amoxicillin-resistant) bacteria. The infection models studied included intraperitoneal infections, a mouse pneumonia, experimental pyelonephritis, and local lesions caused by Staphylococcus aureus and Bacteroides fragilis. The distribution of amoxicillin and clavulanic acid in infected animals after the administration of amoxicillin-clavulanic acid was evaluated by measurement of the concentrations of the substances present in specimens collected at the sites of infection. The results showed that both amoxicillin and clavulanic acid were well distributed in the animal body after the administration of amoxicillin-clavulanic acid formulations, being present in significant concentrations at various sites of infection, e.g., peritoneal washings, pleural fluid, pus, and infected tissue homogenates. In a number of cases, the amoxicillin concentrations measured after the administration of BRL 25000 were higher than those found after treatment with amoxicillin alone, presumably as a result of inhibition of bacterial beta-lactamases by clavulanic acid at the site of infection. The ability of clavulanic acid to protect amoxicillin in vivo was confirmed by the efficacy of amoxicillin-clavulanic acid formulations in the treatment of the infections studied, most of which were refractory to therapy with amoxicillin.

Amoxicillin↗
PubMed1982

Classification of beta-lactamase-producing bacteria.

The resistance of bacteria to beta-lactam antibiotics, penicillins or cephalosporins, is usually associated with the production of beta-lactamase enzymes which are capable of inactivating these compounds. A number of recent surveys have reported a significant increase in the frequency of isolation of beta-lactamase-producing strains of bacteria from infections in general practice in the United Kingdom. A wide variety of bacterial beta-lactamases with different properties have been described and it is now recognised that most bacteria produce a chromosomally-mediated beta-lactamase which is characteristic of each species. In addition, Gram-negative bacteria may acquire beta-lactamases which are mediated by plasmids which are readily transferable by cell to cell contact. Schemes for the classification of bacterial beta-lactamases are outlined.

Bacteria↗
PubMed1981

P-24: a human leukemia-associated and lymphohemopoietic progenitor cell surface structure identified with monoclonal antibody.

This study was directed at surface structures that are found on human lymphohemopoietic progenitor cells in normal and leukemic bone marrow. A monoclonal antibody was produced against an acute lymphoblastic leukemia (ALL) cell line of the pre-B phenotype; this antibody (BA-2) was used to demonstrate a cell surface polypeptide of approximately 24,000 mol wt that migrates similarly in both reduced and nonreduced form. This polypeptide, p24/BA-2, was shown by immune precipitation and gel electrophoresis and cell distribution studies to be different from HLA-DR and gp 100/cALLa. p24/BA-2 was present on the surface of 77% (54/70) of cases of non-T, non-B ALL; BA-2 staining was less bright or nondetectable in surface Ig+ (SIg+) chronic lymphocytic leukemia (CLL) and T ALL and nondetectable on peripheral T and B lymphocytes. Approximately 3% of bone marrow mononuclear cells were p24/BA-2+, and these cells were E rosette-, surface (SIg-), and nonphagocytic. Marrow TdT+ progenitor cells were frequently p 24/BA-2+. Results suggest that p24/BA-2 represents a surface structure present on lymphohemopoietic bone marrow progenitor cells and that most common types of ALL bear the p25/BA-2 structure.

Antibodies↗
PubMed1981

Mapping cell surface antigen expression of haemopoietic progenitor cells using monoclonal antibodies.

A library of monoclonal antibodies which show selective reactivity with particular cells or gene products (e.g. HLA-DR, glycophorin) of different cell lineages in the haemopoietic system has been compiled. Using these probes in conjunction with the fluorescence-activated cell sorter (FACS) the pattern and sequence of cell surface antigenic expression on haemopoietic progenitor cells have been mapped. A cell is identified in bone marrow which has a unique membrane phenotype and the nuclear enzyme terminal deoxynucleotidyl transferase. Its composite phenotype is identical to that seen in the common variant of acute lymphoblastic leukaemia (ALL). It is suggested that this cell is a putative B lineage progenitor which provides the major target for ALL. Detailed analysis of erythroid differentiation with monoclonal antibodies on the FACS reveals an intriguing pattern of antigenic expression in which HLA-DR, glycophorin and band III appear in sequence. HLA-DR (Ia-like antigen) may be present on all or most committed haemopoietic progenitor cells and could play an important role in cell interactions regulating early haemopoiesis.

Animals↗
PubMed1981

Ubiquitous cell-surface glycoprotein on tumor cells is proliferation-associated receptor for transferrin.

A murine monoclonal antibody (OKT9) raised against human leukemic cells binds to a wide variety of leukemia and tumor cell lines and to a minority of leukemia cells taken directly from patients. Fetal thymus and liver are strongly reactive as are some normal, immature hemopoietic cells and activated lymphocytes. Reactivity with OKT9 appears to correlate with proliferation status in both normal and malignant populations. Biochemical analysis indicates that this structure is a approximately equal to 180,000-dalton glycoprotein with two disulfide-bonded subunits of approximately equal to 90,000-daltons. Isolation of the transferrin receptor from a T-cell line (MOLT-4) indicates that it also has a dimeric approximately equal to 180,000-dalton structure. Radio-labeled transferrin bound to its receptors can be specifically precipitated by the monoclonal OKT9, although the latter does not bind transferrin itself, indicating that the antigenic structure defined by this antibody is likely to be the transferrin receptor.

Animals↗
PubMed1981

BRL 17421, a novel beta-lactam antibiotic, highly resistant to beta-lactamases, giving high and prolonged serum levels in humans.

BRL 17421 is a new semisynthetic beta-lactam antibiotic with an unusual spectrum of antibacterial activity. The compound exhibits exceptional stability to a wide range of bacterial beta-lactamases and is active against the majority of Enterobacteriaceae, including strains highly resistant to many of the penicillins and cephalosporins currently available. Among the clinical isolates of Enterobacteriaceae tested, the frequency of strains resistant to BRL 17421 was found to be low, and there was a slow rate of emergence of resistance during in vitro studies. BRL 17421 was highly active against Haemophilus influenzae and Neisseria gonorrhoeae, including beta-lactamase-producing strains. The compound was markedly less active against Pseudomonas aeruginosa and Bacteroides fragilis than against the Enterobacteriaceae. Against the gram-positive bacteria, BRL 17421 showed a very low level of activity. BRL 17421 was found to be 85% bound to human serum, and the antibacterial activity was diminished two- to fourfold in the presence of human serum. Against experimental infections in mice, the activity of BRL 17421 reflected the properties observed in vitro. Studies in human volunteers showed unusually high and prolonged serum concentrations of the compound after parenteral dosage, with a serum half-life of about 5 h, and approximately 85% of the dose was recovered unchanged in the urine. BRL 17421 was poorly absorbed after oral administration. The compound was well tolerated after intramuscular and intravenous administration in volunteers, with no adverse side effects.

Animals↗
PubMed1981

The biochemical characterization of a cell surface antigen associated with acute lymphoblastic leukemia and lymphocyte precursors.

The acute lymphoblastic leukemia- (ALL) associated membrane antigen is a single glycosylated polypeptide of approximate m.w. of 100,000 (gp100), containing no intrachain disulfide linkages. Approximately 50% of gp100 will bind to lentil lectin, whereas 100% will bind to the lectin from Ricinus communis. Both lentil-binding and lentil nonbinding forms of the antigen appear to be identical by 2-dimensional isoelectric focusing/SDS polyacrylamide gel electrophoresis and peptide mapping. Carbohydrate, although contributing approximately 20 to 25% of the m.w., appears not to be involved in the antigenic site of the ALL antigen as judged by precipitation of a molecule after tunicamycin treatment of cells or glycosidase digestion. Charge shift electrophoresis and labeling with the lipophilic nitrene reagent hexanoyl diiodo-N-(4-azido-2-nitrophenyl)-tyramine suggests that the cALL antigen is probably not an integral membrane protein; however, it remains tightly bound to the plasma membrane after subcellular fractionation. A glycoprotein of the same m.w. has been detected by immunoprecipitation on bone marrow cells of nonleukemic patients. serologic studies indicate that the cALL-associated antigen is found on the terminal transferase-positive lymphoid cells, and it therefore seems likely that the gp100 molecule is a normal gene products of lymphocyte precursors.

Animals↗
PubMed1981

Exploitation of monoclonal antibodies: a "who's who" of haemopoietic malignancy.

A library of monoclonal antibodies plus "conventional' markers (e.g. anti-TdT) have been used to explore the detailed phenotypes of leukaemic cells in relation to normal haemopoietic differentiation. This analysis reveals that consistent, composite phenotypes of different subclasses of lymphoid malignancies closely mimic those of corresponding normal cells at equivalent levels of maturation. It is suggested that three major target cell populations are available for lymphoid malignancy: the pluripotential stem cell (e.g. "lymphoid' blast crisis of CGL), lymphoid progenitors or stem cells in the bone marrow (non-T ALL) or thymus (T-ALL, T-NHL) and long lived, mature and immunocompetent T and B cells (T-CLL, PLL, Sézary and B-CLL, lymphoma respectively). The major phenotypes documented in different leukaemias represent the level of "maturation arrest' imposed on the dominant subclone; this is determined by, but not necessarily synonymous with, the "target cell' and associated clonogenic cell population in the leukaemia. No consistent major abnormalities of gene expression are revealed by this investigation and although they may exist (e.g. loss or acquisition of antigens with malignant progression) we suggest that they are irrelevant to the central issue of what alterations are essential and sufficient for the evolution of clonogenic leukaemic cells. We propose instead that subtle changes, which uncouple proliferation and differentiation, are all that is required.

Antibodies, Monoclonal↗
PubMed1980

Inhibition of normal human granulopoiesis in vitro by non-B non-T lymphocytes.

Normal non-adherent mononuclear cells were shown to inhibit colony formation by normal human marrow cells cultured for 7 d in semi-solid agar. Inhibition was the same using cells from the marrow donor or from an unrelated normal subject, and was shown to be dose-dependent over the range of 4 X 10(5) to 6 X 10(3) mononuclear cells per 1 X 10(5) marrow cells plated. Inhibition was not seen in 14 d cultures, and it is postulated that colony-forming cells sensitive to lymphocyte inhibition belonged to the population known to give rise to colonies after 7 d in culture. Cell fractionation studies showed that inhibition was due to non-B non-T lymphocytes, purified B cells or T cells being neither inhibitory nor stimulatory. Inhibition was only shown with intact viable lymphocytes and it was not possible to extract inhibitory activity from the cells, or to produce inhibition by media conditioned by lymphocytes. The effect was apparently due to a direct action on colony-forming cells in the marrow and was not due to inhibition of colony stimulating activity (CSA) production, or to absorption or inactivation of CSA. These results emphasize the need to include appropriate controls when looking for possible cell-mediated inhibitors in disease states, particularly when 7 d cultures are used.

Cells, Cultured↗
PubMed1980

Comparative bactericidal effects of azlocillin and ticarcillin against Pseudomonas aeruginosa.

Azlocillin was relatively ineffective against actively growing cultures of Pseudomonas aeruginosa in tests of bacteriolytic and bactericidal activity in which ticarcillin demonstrated pronounced bactericidal effects over a wide range of concentrations. Microscopic observation showed that azlocillin generally induced the formation of filamentous cells of P. aeruginosa which lysed only slowly, but ticarcillin caused the production of spheroplasts and subsequent rapid lysis. During the course of the bactericidal tests, azlocillin was inactivated, presumably by the beta-lactamase produced by P. aeruginosa, and the filamentous cells resumed normal cell division and growth. In contrast, there was no loss of ticarcillin activity, and there was no evidence of resumption of growth of P. aeruginosa in the presence of ticarcillin. These results suggest that the different bactericidal effects demonstrated by azlocillin and ticarcillin against P. aeruginosa are related primarily to dose-related differences in inhibition of cell wall synthesis and secondarily to the instability of azlocillin to pseudomonal beta-lactamase.

Azlocillin↗
PubMed1980

Sensitivity to carbenicillin and ticarcillin, and the beta-lactamases of Pseudomonas aeruginosa in the UK in 1978-79.

A total of 438 strains of Pseudomonas aeruginosa supplied by 10 hospitals in the UK reporting an increase in resistance to carbenicillin was tested for sensitivity to carbenicillin and ticarcillin. It was found that 85% of the strains were inhibited by 125 microgram carbenicillin/ml and 87% by 50 microgram ticarcillin/ml, and that ticarcillin was from two- to four-fold more active than carbenicillin against the majority of these strains. Strains with a high level of resistance to carbenicillin (MIC greater than 1000 microgram/ml) possessed constitutive beta-lactamases, and five different types of enzyme were identified. There was good correlation between minimum inhibitory concentrations and the results of disc sensitivity tests in this study, 82% with the 100 microgram carbenicillin disc and 90( with the 75 microgram ticarcillin disc, but results reported in the hospital laboratory tests with the carbenicillin disc were less satisfactory (64% correlation). From a comparison with data reported in 1967 there does not appear to have been a significant increase in the incidence of carbenicillin-resistant strains of Ps aeruginosa in the UK.

Carbenicillin↗
PubMed1980

The predictive value of myocardial radioisotope scanning in animals treated with doxorubicin.

Thirty-four New Zealand white rabbits were treated with doxorubicin and imaged weekly with Tc-99m pyrophosphate to define the value of abnormal myocardial images in predicting doxorubicin-induced cardiac toxicity. Increased myocardial uptake was detected in most animals on sustained treatment with doxorubicin. A greater proportion of the heart was involved with doxorubicin-related histologic changes in animals with strongly positive myocardial images than in treated animals with moderately positive or normal scans. The myocardial images returned to normal levels 2--6 wk after doxorubicin was discontinued. Five of seven rabbits that received doxorubicin after they had three moderately positive myocardial scans, died from congestive heart failure. Three rabbits whose doxorubicin was discontinued because of scan findings, survived for 6 wk or more before dying from renal failure. The three rabbits who received the highest total dose of doxorubicin died of renal failure without developing abnormal myocardial scans.

Animals↗
PubMed1979

Comparative antibacterial activity of azlocillin, mezlocillin, carbenicillin and ticarcillin and relative stability to beta-lactamases of pseudomonas aeruginosa and klebsiella aerogenes.

The antibacterial activities of two ureidopenicillins, azlocillin and mezlocillin, were compared with those of the alpha-carboxypenicillins, carbenicillin and ticarcillin, against a large number of gram-positive and gram-negative bacteria. All four penicillins were active against a wide range of bacteria including Pseudomonas aeruginosa, but there were differences in the antibacterial spectra and in the antibacterial effects demonstrated by the two classes of penicillins. In particular, the minimum inhibitory concentrations of azlocillin and mezlocillin against Klebsiella aerogenes and against P. aeruginosa were greatly influenced by the size of bacterial inoculum tested whereas there was no significant inoculum effect with carbenicillin and ticarcillin. In stability tests, the ureidopenicillins were inactivated rapidly by the beta-lactamases of K. aerogenes and P. aeruginosa whereas the alpha-carboxypenicillins were stable. It seems probable that the inoculum effect seen with azlocillin and mezlocillin in antibacterial tests with K. aerogenes and P. aeruginosa is associated with the instability of the compounds to the beta-lactamases of these bacteria.

Carbenicillin↗
PubMed1979

Antibacterial activity and synergy, in vitro and in vivo, of a combination of amoxycillin and flucloxacillin.

The antibacterial activity of a combination of equal parts of amoxycillin and flucloxacillin was compared in vitro and in vivo with that of amoxycillin and flucloxacillin against a range of gram-positive and gram-negative bacteria. The combination generally showed additive effects against bacteria sensitive to the individual penicillins and there was no evidence of antagonism, but synergistic effects were observed between amoxycillin and flucloxacillin against certain amoxycillin-resistant gram-negative bacilli. The extent of synergism varied according to the particular bacterial species under test and synergy was observed only against bacteria with chromosomally-mediated beta-lactamases and not against bacteria with R-factor-mediated beta-lactamases. In general, amoxycillin + flucloxacillin demonstrated activity against experimental mouse infections in good agreement with demonstrated activity against experimental mouse infections in good agreement with its in vitro activity, and synergy was produced against a range of gram-negative bacilli in vivo. The data suggest that clinical trial with amoxycillin + flucloxacillin in the treatment of selected infections including those due to some amoxycillin-resistant bacteria may well be justified.

Amoxicillin↗
PubMed1978

Inhibitor of in-vitro granulopoiesis in plasma of patients with renal failure.

Plasmas from 31 patients with moderately severe to severe renal failure inhibited granulopoietic colony formation in human marrow in vitro. The inhibitory activity could not be removed by in-vitro dialysis but was present in an ultrafiltered fraction of molecular weight less than 25 000 daltons. It inhibited the production of colony-stimulating activity (C.S.A.) by leucocytes in the culture system but had little or no effect on preformed C.S.A. or on the granulopoietic colony-forming cell itself. The level of plasma inhibitory activity correlated with the degree of azotaemia but not with the neutrophil or monocyte counts. Despite the potency with which granulopoiesis was inhibited in vitro, none of the patients was severely neutropenic, and only 4 had mild neutropenia (neutrophil count 1.5--2.1 x 10(9)/1).

Bone Marrow↗