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Biomedical subjects

A L Green

Publications and source records attributed to A L Green.

At least 37 records · Page 2Linked to original sources
PubMed1987

The inhibition of monoamine oxidase by tricyclic antidepressants: the influence of the nature of the substrate and the source of the enzyme.

Five tricyclic antidepressants, amitriptyline, clomipramine, desipramine, imipramine and iprindole, have comparable potencies as inhibitors of monoamine oxidase in rodent brain and liver. With rodent brain, potency was always greater with phenethylamine as substrate than with benzylamine, and was generally least with 5-HT. With mouse liver, in which monoamine oxidase is mainly B type, potency with tyramine and dopamine as substrates was close to that found with phenethylamine. The kinetics of inhibition varied with both the substrate and the tissue, and were inconsistent with a simple ping-pong model for substrate oxidation. The relevance of these observations to clinical effectiveness is discussed.

Animals↗
PubMed1986

Immunocytochemical localization of corticosteroid-binding globulin in rat tissues.

Previous studies utilizing steroid-binding assays have suggested that corticosteroid-binding globulin (CBG)-like glucocorticoid binding sites are present in various tissues of the rat. It is not known, however, whether such binding reflects the intracellular presence of CBG derived from serum or a special class (type III) of receptors. In order to elucidate this problem, immunocytochemical localization of rat CBG was carried out using a specific antiserum prepared against rat serum CBG and the peroxidase-antiperoxidase technique. Positive staining was found in certain cells of the liver, the distal and/or convoluted tubules of the kidney, the uterus, the follicular cells of the thyroid, and some cells of the anterior pituitary. Other tissues including heart, muscle, thymus, hypothalamus, supraoptic and paraventricular nuclei, and diaphragm were negative. The presence of immunoreactive CBG in specific cells of some glucocorticoid-responsive tissues and not others raises interesting questions concerning the transport of glucocorticoids and their mechanism of action.

Animals↗
PubMed1985

Duration of admission for febrile convulsions?

Records of 199 children aged 5 to 71 months (mean 22.8) admitted after febrile convulsion were examined. Although 32 had recurrent convulsions (some before admission) none suffered a convulsion more than 24 hours after hospital admission.

Child, Preschool↗
PubMed1983

A theoretical kinetic analysis of the protective action exerted by eserine and other carbamate anticholinesterases against poisoning by organophosphorus compounds.

The protection exerted by carbamate anticholinesterases against the lethal effects of organophosphate anticholinesterases is interpreted kinetically. The protective action is shown to depend on the provision (by carbamylation) of a pool of sequestered cholinesterase resistant to organophosphates but which furnishes (by decarbamylation) sufficient active enzyme to essential cholinergic synapses to ensure survival until all free organophosphate is cleared from the tissues. The two main factors governing the extent of protection are the minimum cholinesterase activity compatible with survival and the "enzyme conservation index" defined essentially as the ratio of the rate of enzyme decarbamylation to the rate of enzyme phosphorylation; the lower the "minimum essential cholinesterase" and the higher the "enzyme conservation index", the greater the protection. The theory is shown to be in excellent qualitative agreement with experiment.

Animals↗
PubMed1980

p-Methoxyamphetamine, a potent reversible inhibitor of type-A monoamine oxidase in vitro and in vivo.

p-Methoxyamphetamine is over 20 times as potent as (+)-amphetamine as an inhibitor of 5-HT oxidation by monoamine oxidase in mouse brain in vitro, with a Ki value of 0.22 microM. It is highly selective towards A-type monoamine oxidase and possesses only weak activity against the B-type enzyme (Ki value about 500 microM with benzylamine as substrate and solubilized rat liver mitochondria as enzyme source). It is 10 times more active than (+)-amphetamine in protecting mouse brain monoamine oxidase from inhibition by phenelzine in vivo. o-Methoxy- and m-methoxyamphetamines inhibit monoamine oxidase both in vitro and in vivo with potencies comparable with, or less than that of (+)-amphetamine.

Amphetamine↗
PubMed1979

Retinoblastoma Y79 cell line: a study of membrane structures.

The continuous retinoblastoma cell line Y79, grown in suspension culture, has been examined by transmission and scanning electron microscopy, including freeze-fracture replica preparations. Four classes of cells were distinguishable by their size and surface characteristics. The surface structures included blebs, filopodia, lamellipodia, microvilli, and microplicae. The possible origin of a most unusual type of cell, apparently forming natural clones, is discussed.

Cell Line↗
PubMed1978

The relationship between cholinesterase inhibition in the chick biventer cervicis muscle and its sensitivity to exogenous acetylcholine.

The effect of physostigmine has been studied on cholinesterase in homogenates of chick biventer cervicis muscles and on the contractile responses of the intact muscles to acetylcholine and carbachol. The concentration of physostigmine required to produce the maximum increase in sensitivity to acetylcholine almost completely inhibited the cholinesterase in muscle homogenates. This concentration of physostigmine had no effect on muscle contractures elicited by carbachol. By taking account of the combined effects of acetylcholine diffusion and enzymic hydrolysis, a quantitative theoretical relationship has been derived between the level of cholinesterase activity in cylindrical muscles and the fractional occupancy of the acetylcholine receptors in these muscles in the presence of different concentrations of exogenous acetylcholine. This theory attributes the thousand-fold increase in sensitivity to exogenous acetylcholine produced by anticholinesterases in chick biventer cervicis muscles largely to an alteration in acetylcholine concentration gradient within the muscle and accounts satisfactorily for the shift in the dose-response curve for acetylcholine which occurs after treatment of the muscles with various concentrations of physostigmine.

Acetylcholine↗