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Biomedical subjects

A G Taylor

Publications and source records attributed to A G Taylor.

At least 37 records · Page 2Linked to original sources
PubMed1991

Effects of NPPB (5-nitro-2-(3-phenylpropylamino)benzoic acid) on chloride transport in intestinal tissues and the T84 cell line.

NPPB (5-nitro-2-(3-phenylpropylamino)benzoic acid) has been reported to block Cl- channels in isolated rabbit nephrons with high potency (IC50 = 80 nM). The effects of this compound on Cl(-)-mediated transport processes in intestinal tissues have been studied using agonist-stimulated short-circuit current (T84) in Ussing chamber experiments and 36Cl- fluxes in monolayers of a colonic cell line (T84). NPPB inhibited PGE1-stimulated Isc in rabbit distal colon and ileum at concentrations in the range 20 to 100 microM. However, NPPB at the same concentrations also inhibited glucose-stimulated Isc in rabbit ileum, suggesting that its effects were not restricted to those on Cl- transport. Consistent with this, exposure of rabbit distal colon to 100 microM NPPB was found to reduce endogenous ATP levels by 69%, implying that, at these concentrations, NPPB could impair active transport processes by an effect on cellular energy metabolism. Clear evidence for a direct effect of NPPB on epithelial chloride channels was found in studies on Cl- fluxes in T84 cell monolayers. NPPB inhibited VIP-stimulated Cl- uptake into T84 cells with an IC50 of 414 microM. NPPB (1 mM) also inhibited Cl- efflux from pre-loaded cells confirming its effect as a weak Cl- channel blocker in this system.

Adenocarcinoma↗
PubMed1991

Taxonomic considerations of Bartonella bacilliformis based on phylogenetic and phenotypic characteristics.

The 16S-rRNA gene of Bartonella bacilliformis was amplified using the polymerase-chain reaction (PCR). The amplification product was sequenced using a linear-PCR procedure and compared with other published 16S-rRNA sequences. The results of this analysis placed B. bacilliformis in the alpha subgroup of the proteobacteria, and more specifically demonstrated its close phylogenetic relationship to Rochalimaea quintana. This relationship is supported by similarities in the size and mean base composition of the genomes of the two species, and by shared phenotypic characteristics.

Bartonella↗
PubMed1991

Treatment failure and recurrent human listeriosis.

We review 12 patients and report an additional two new patients, each of whom had two episodes of listeriosis. In seven patients the two episodes were due to the same strain of Listeria monocytogenes, and we speculate that this was a reactivation of the original infection. In one patient, isolates of L. monocytogenes from the two episodes differed, suggesting a chance reinfection. Twelve of the patients in this series received inappropriate therapy. Ampicillin plus an aminoglycoside for three to four weeks remain the treatment of choice.

Adult↗
PubMed1991

A comparison of probes for restriction fragment length polymorphism (RFLP) typing of Legionella pneumophila serogroup 1 strains.

The use of probes derived from rRNA sequences to detect restriction fragment length polymorphisms (RFLPs) associated with the ribosomal RNA genes for epidemiological typing (ribotyping) is a powerful and readily applicable tool. Different probes and enzymes for ribotyping were compared for a series of 73 unrelated Legionella pneumophila serogroup 1 strains. The probes compared were cDNAs, transcribed from L. pneumophila or Escherichia coli rRNA subunits, and a cloned L. pneumophila rRNA gene. The cloned rRNA gene probe gave the best discrimination and this probe was further compared with cloned probes comprised of randomly selected (non-rRNA) parts of the L. pneumophila chromosome. In this instance the greatest discrimination was achieved when one of the non-ribosomal RNA gene probes was employed. The overall discrimination of RFLP typing was enhanced by combining the data obtained with both rRNA and non-rRNA probes.

Bacteriophage lambda↗
PubMed1990

By 1023/SK&F 96022: biochemistry of a novel (H+ + K+)-ATPase inhibitor.

The mechanism by which the substituted benzimidazole sulphoxide BY 1023/SK&F 96022 inhibited the (H+ + K+)-ATPase, the enzyme responsible for hydrogen ion secretion in the stomach, was studied in a variety of in vitro preparations. In gastric preparations that were capable of active hydrogen ion transport with consequent lumenal acidification, BY 1023/SK&F 96022 inhibited with high potency and in a time-dependent manner consistent with the acid-induced conversion of the parent benzimidazole sulphoxide to a covalent inhibitor (cyclic sulphenamide). The following IC50 values were obtained for the inhibition of aminopyrine accumulation: intact gastric glands stimulated with 1 mM dibutyryl cAMP, 1.0 microM; permeabilized gastric glands stimulated with 5 mM ATP, 0.42 microM; intact gastric vesicles stimulated with 150 mM KCl, 9 microM valinomycin and 2 mM MgATP, 3.5 microM. In a preparation that could not generate pH gradients, lyophilized gastric vesicles at pH 7.4, BY 1023/SK&F 96022 inhibited K(+)-stimulated ATPase activity with relatively low potency, 70 microM, indicating its good chemical stability at neutral pH. As assessed by ATPase inhibition, this stability was three times greater than that of omeprazole. Inhibition by BY 1023/SK&F 96022 was not reversed by dilution in either permeabilized gastric glands or intact gastric vesicles. Inhibition could, however, be completely reversed by subsequent incubation with 20 mM beta-mercaptoethanol (intact gastric glands) or 100 mM dithiothreitol (intact gastric vesicles) suggesting a disulphide link between inhibitor and enzyme. The concentration of glutathione needed to protect against inhibition by BY 1023/SK&F 96022 was 10,000 times higher in intact, compared with lyophilized, gastric vesicles indicating an interaction with the lumenal (extra-cellular) face of the (H+ + K+)-ATPase. BY 1023/SK&F 96022 and omeprazole were also found to inhibit acidification in purified kidney lysosomes with IC50 values of 194 and 75 microM, respectively. Protection by 10 microM glutathione suggested that this did not result from intralysosomal activation of these inhibitors. Thus, BY 1023/SK&F 96022 has the combined properties of good chemical stability at neutral pH and effective conversion to the cyclic sulphenamide at acidic pH. In this way the activation to the cyclic sulphenamide may be optimally restricted to the parietal cell canaliculus.

2-Pyridinylmethylsulfinylbenzimidazoles↗
PubMed1990

Psychologic distress of chronic pain sufferers and their spouses.

Recent research has begun to document the relationship between chronic pain and psychologic distress among pain patients, yet little attention has been given to the spouses' reaction to the chronic pain condition. The results of this research using the Symptom Checklist-90 (SCL-90) to assess the psychologic distress among both chronic pain sufferers and spouses (61 couples) reveal elevated distress scores among both groups when compared with the norms from a nonpatient sample. Patients and spouses present similar profiles according to the SCL-90 subscales, with patients' scores significantly higher on the somatization, hostility, and psychoticism subscales. No differences by sex were found.

Adult↗
PubMed1990

Peak flow measurement as a screening test for restrictive pulmonary disorders.

We tested whether measurement of peak flow was useful in determining the presence and severity of restrictive pulmonary disorders in addition to its recognized use in the diagnosis and management of airflow obstruction. In 102 patients with various causes of restriction of lung volumes, we found that peak expiratory flow correlated well with forced vital capacity. As a diagnostic test it was useful in restrictive disorders, except in fibrosing alveolitis where it consistently failed to detect abnormality.

Forced Expiratory Flow Rates↗
PubMed1990

Phenotypic variation amongst genotypically homogeneous Legionella pneumophila serogroup 1 isolates: implications for the investigation of outbreaks of Legionnaires' disease.

One hundred and seventy-nine isolates of Legionella pneumophila serogroup 1, obtained from a site associated with an outbreak of Legionnaires' disease, were examined by monoclonal antibody subgrouping, restriction fragment length polymorphism typing, restriction endonuclease analysis and plasmid content. Nine distinct phenotypes were detected but at the genotypic level all strains were closely related. The data presented indicate that phenotypic variation of a single parent strain can occur within an environmental site. The implications of these findings are discussed in relation to the investigation of outbreaks of Legionnaires' disease.

Culture Media↗
PubMed1990

A method for typing strains of Legionella pneumophila serogroup 1 by analysis of restriction fragment length polymorphisms.

A restriction fragment length polymorphism (RFLP) typing method for Legionella pneumophila serogroup 1 was developed. The method depended upon the use of cloned EcoR1 fragments from L. pneumophila (Knoxville-1) probing Nci1 restriction fragments of chromosomal DNA. Examination of strains of L. pneumophila which were apparently unrelated showed that inter-strain RFLPs were common, and these formed the basis of the typing scheme. The technique was found to be highly reproducible and discriminatory. When the RFLP data were compared to that obtained by monoclonal antibody (MAb) subgrouping both methods of strain differentiation gave consistent results. The isolates examined by either method were also sub-divided by the alternative technique. The analysis of RFLPs by cloned probes should be of considerable epidemiological value.

Antibodies, Monoclonal↗
PubMed1990

Typing of Legionella pneumophila serogroups 2-14 strains by analysis of restriction fragment length polymorphisms.

A typing method based on analysis of restriction fragment length polymorphisms has previously been developed for Legionella pneumophila serogroup 1. Here data are presented demonstrating the utility of this method for typing strains of all other L. pneumophila serogroups described to date. The method, which is highly discriminatory, should be of considerable value in epidemiological investigations of legionella infections.

Bacterial Typing Techniques↗
PubMed1990

Evaluation of urinary antigen ELISA for diagnosing Legionella pneumophila serogroup 1 infection.

The enzyme linked immunosorbent assay (ELISA) described was developed to detect a soluble antigen in the urine of patients with Legionnaires' disease caused by Legionella pneumophila serogroup 1 (L.pn 1). The assay was evaluated and showed good specificity (100%) and intra-assay reproducibility. Antigen was detected in the urine of 93 (77%) of 120 patients, overall, and in 86% of patients from whom a specimen obtained within seven days of onset of illness was available. On all but one occasion the first urine sample taken from a patient for whom a positive ELISA result was obtained, was itself positive. In one case antigen was not detected at four days but was present on the fifth day after onset of symptoms. In two patients urinary antigen was detectable as early as two days after onset of symptoms. In another the antigen persisted for at least 60 days. More than half the patients, however, had stopped producing detectable antigen within 14 days of onset of symptoms. It is therefore important that where Legionnaires' disease is suspected urine is collected as early as possible in the course of the disease.

Antigens, Bacterial↗
PubMed1989

The binding of a K+ competitive ligand, 2-methyl,8-(phenylmethoxy)imidazo(1,2-a)pyridine 3-acetonitrile, to the gastric (H+ + K+)-ATPase.

2-Methyl,8-(phenylmethoxy)imidazo(1,2-a)pyridine 3-acetonitrile (SCH 28080) is a freely reversible K+ site inhibitor of the gastric (H+ + K+)-ATPase. In the presence of 2 mMMgSO4, [14C]SCH 28080 bound saturably to gastric vesicle preparations containing the (H+ + K+)-ATPase and was displaced by lumenal K+. A binding stoichiometry of 2.2 +/- 0.1 mol of SCH 28080/mol of catalytic phosphorylation sites was observed. The affinity of SCH 28080 binding was increased approximately 10-fold (to 45 nM) in the presence of 2 mM ATP. High affinity binding also occurred with 2 microM ATP but not with up to 200 microM D-[beta, gamma-CH2]ATP, suggesting that high affinity binding was to a phosphorylated form of the enzyme. In the presence of ATP, the association rate constant was linearly related to the concentration of SCH 28080. However, the association and dissociation rates of SCH 28080 binding were slow, especially at low temperature (at 1.5 degrees C half-maximal binding of 50 nM SCH 28080 was calculated to occur after 232 s). Binding appeared to be predominantly entropy driven with a high activation energy (40 kJ/mol at 37 degrees C). In the absence of ATP, the association rate constant was not linearly related to the concentration of SCH 28080, suggesting that a conformational change in the enzyme was required before binding could occur.

Adenosine Triphosphatases↗
PubMed1989

The use of monoclonal antibodies to demonstrate Listeria monocytogenes in post mortem tissue using a direct immunofluorescence technique, and to detect a soluble antigen in CSF supernatants using an ELISA.

A direct immunofluorescence technique was developed using FITC conjugates of anti-listeria antibodies (CL2 and CL17). Using this technique Listeria monocytogenes (whole cells) were observed in post mortem tissue from 3 patients where listeriosis had been proven by the isolation of the bacterium, and also from a patient where listeriosis was suspected. Using one of these monoclonal antibodies (CL2) an indirect antigen capture ELISA was developed for the detection of soluble antigen. Soluble antigen was detected in cerebrospinal fluid (CSF) from 27% of patients infected with L. monocytogenes serogroup 4 and 2% of patients where listeriosis was suspected. The test was 100% specific in that antigen was not detected in 270 other CSF samples tested. Antigen was only detected in CSF samples taken within 7 days after onset of illness.

Adolescent↗
PubMed1989

The use of monoclonal antibodies in the characterization and purification of cell surface antigens of Listeria monocytogenes serogroup 4.

Soluble antigen was prepared from Listeria monocytogenes serovar 4b using a formamide extraction method. Antigenic material was detected in this extract by gel diffusion and ELISA using anti-Listeria monoclonal antibodies. Using this ELISA, antigen was detected in cerebrospinal fluid (CSF) during infection due to L. monocytogenes serovar 4b with wells coated with three of the monoclonal antibodies (CL1, CL2 and CL3). The antigen binding of CL3 was found to be greatly influenced by changes in ionic strength, and these properties were utilized in an affinity purification method. An analysis of the antigens was carried out using crossed immunoelectrophoresis and this indicated that the crude formamide extract contains a number of distinct antigens. A group of three antigens of differing electrophoretic mobilities were demonstrated in the affinity purified material.

Animals↗