PubMed Health⌕ Search

Biomedical subjects

A Barton

Publications and source records attributed to A Barton.

At least 73 records · Page 4Linked to original sources
PubMed1986

Uptake of gamma-aminobutyric acid and glycine by synaptosomes from postmortem human brain.

Synaptosomes prepared from frozen postmortem human brain accumulated the neurotransmitter gamma-aminobutyric acid (GABA) and the conformationally restricted GABA analogue cis-3-aminocyclohexanecarboxylic acid (ACHC) by a sodium-dependent, temperature-sensitive, high-affinity transport process into an osmotically sensitive compartment. This transport process could be inhibited by GABA analogues (ACHC, 2,4-diaminobutyric acid, nipecotic acid, arecaidine, guvacine) that have been shown in studies on other species to be relatively selective for neuronal rather than glial uptake systems, whereas the glial uptake inhibitor beta-alanine was ineffective. Synaptosomes prepared from frozen post-mortem human medulla and spinal cord, but not cerebral cortex, took up the neurotransmitter glycine by a sodium-dependent high-affinity transport process. The kinetic parameters for the high-affinity uptake of GABA, ACHC, and glycine were Km = 10 +/- 3, 49 +/- 19, and 35 +/- 19 microM; and Vmax = 98 +/- 15, 84 +/- 25, and 5.5 +/- 2.5 nmol/min/100 mg protein, respectively. These results demonstrate the feasibility of using human CNS preparations for studying GABA and glycine uptake, and suggest that such studies may be useful neurochemical markers for transmitter-specific presynaptic terminals in health and disease.

Aged↗
PubMed1982

Oxidative inactivation of leukotriene C4 by stimulated human polymorphonuclear leukocytes.

Leukotriene C(4) (LTC(4)) was metabolized by human polymorphonuclear leukocytes (PMNs) stimulated with phorbol myristate acetate (PMA) into three sets of products. These products differed in mobility on reverse-phase high-performance liquid chromatography (RP HPLC) from LTC(4) and also from leukotriene D(4) (LTD(4)) and leukotriene E(4) (LTE(4)), the sequential products of peptide cleavage of LTC(4). Products I, II, and III were eluted as doublets with an average retention time for each doublet of 7.5 +/- 0.3, 10.5 +/- 0.6, and 16.3 +/- 1.1 min (mean +/- SD), respectively, as compared with 13.8 min for LTC(4). Doublet I material was biologically inactive and showed <5% of the immunoreactivity of LTC(4), doublet II material had 1% of the spasmogenic activity of LTC(4) on the guinea pig ileum and was equally immunoreactive, and doublet III material was neither biologically active nor immunoreactive. When [14,15-(3)H]LTC(4) and [(35)S]LTC(4) were metabolized, all three doublet products retained the (3)H label, whereas only the doublet I and doublet II products retained the (35)S label. The UV absorbance spectra of the three sets of metabolites were as follows: doublet I, maximum at 280 nm with shoulders at about 270 and 290 nm; doublet II, maximum at 284.5 nm with shoulders at about 275 and 295 nm; and doublet III, maximum at 269 nm with shoulders at about 259 and 279 nm. The metabolism of LTC(4) to the three classes of functionally inactive products by stimulated PMNs was completely blocked by catalase and azide, indicating a requirement for H(2)O(2) and myeloperoxidase. When hypochlorous acid (HOCl)-considered to be a natural product of the interaction of myeloperoxidase, H(2)O(2), and chloride ion-was formed chemically and allowed to react with LTC(4), the resulting products were indistinguishable by UV and HPLC analyses from the doublet II and doublet III metabolites of LTC(4). The doublet II products were identified as the two diastereoisomeric sulfoxides of LTC(4) by comparison with synthetic reference compounds. The doublet III products were shown to be identical with synthetic samples of (5S, 12S)- and (5S, 12R)-6-trans-LTB(4). The formation of two diastereoisomeric LTC(4) sulfoxides and 6-trans-LTB(4) can be explained in terms of an S-chlorosulfonium ion as the initial reactive intermediate, which subsequently undergoes conversion to product II by hydrolysis and product III by carbocation formation.

Catalase↗
PubMed1981

Vaginitis associated with vaginal malodour.

In two general practices in Perth, Western Australia, the most common microbiological causes of vaginal discomfort in 368 patients were Candida albicans. Gardnerella (Haemophilus) vaginalis, Trichomonas vaginalis and bacteroides fragilis. Amongst patients with abnormal vaginal odour, with or without vaginitis, the most common cause of odour was G. vaginalis. The writers advocate that heavy growths of group B streptococci, Escherichia coli, and enterococci should be considered to be the possible cause of vaginal discomfort. This reinforces the need for care in collection, transportation, and microbiological examination of swabs of the female genital tract. as well as in the clinical interpretation of these reports.

Candida albicans↗
PubMed1976

[The value of pneumomyelography in the investigation of the terminal theca (author's transl)].

Three hundred lumbar air myelograms were selected from a total of 1,500 examinations and their results analysed. The method described in this paper provides significantly more information than conventional myelograms. In the opinion of the author, lumbar air myelography can replace iodinated oils and esters in the diagnosis of disc prolapse, since its accuracy is not significantly inferior. Because of its lack of toxicity it is to be preferred.

Evaluation Studies as Topic↗