Search PubMed⌕ Search

Biomedical subjects

H L White

Publications and source records attributed to H L White.

At least 55 records · Page 3Linked to original sources
PubMed1979

A data processing system for a group of three clinical chemistry laboratories. 1. Hardware and organisation.

A real time data processing system for a group of three clinical chemistry laboratories (one base and two satellite) has been developed as a successor to one used previously. This paper describes both the inadequacies of the previous worksheet-based system and the advantages of the new system, including flexibility, fast response and comprehensiveness, incorporating urgent routine and long delay (that is, endocrine) requests, and the use of a parallel flow work scheme.

Chemistry, Clinical↗
PubMed1979

Catechol-O-methyltransferase activity and classification of depression.

Red blood cell catechol-O-methyltransferase (COMT) activity was compared across different depressive diagnoses. In a sample of 88 depressed inpatients, using defined criteria, no difference was found in respect of enzyme activity and the following categories: primary, secondary, delusional, nondelusional, endogenous, nonendogenous (neurotic), characterological depressions. COMT did not vary with age or sex. A significant increase in COMT activity was noted in agitated, depressed males, as compared to other groups.

Adult↗
PubMed1978

Synthesis of prostaglandin 6-keto F1alpha by cultured aortic smooth muscle cells and stimulation of its formation in a coupled system with platelet lysates.

Lysed aortic smooth muscle cells, when incubated with [14C] arachidonate, synthesized only one radioactive product, which was identified as 6-keto-PGF1alpha. Formation of this product from smooth muscle cell lysates was stimulated when human platelet extracts were added to the system, and further stimulation was observed when imidazole, a selective inhibitor of thromboxane synthesis, was added to this coupled system. These observations indicate that the cyclooxygenase of the smooth muscle cells was rate-limiting, that the prostacyclin synthetase of these cells can utilize endoperoxides produced by platelets, and that blocking of thromboxane synthesis might, under certain conditions, shunt arachidonate metabolism toward prostacyclin formation.

Animals↗
PubMed1978

Inhibition of platelet monoamine oxidase in depressed subjects treated with phenelzine.

The authors treated 19 depressive inpatients double-blind with a mean dose of 78 mg/day of phenelzine for 3 weeks to determine the possible relationship between monoamine oxidase (MAO) inhibition and the effectiveness of phenelzine. Clinical ratings made on the Hamilton Depression Rating Scale, the Beck Depression Inventory, and the SCL-90 indicated a minimum of 60% MAO inhibition had to be achieved for the drug to be consistently beneficial.

Blood Platelets↗
PubMed1977

Diversion of prostaglandin endoperoxide metabolism by selective inhibition of thromboxane A2 biosynthesis in lung, spleen or platelets.

Infusion of arachidonic acid through the guinea pig lung or the cat spleen causes a release of thromboxane A2 and prostaglandins, as measured by bioassay. After incubation of human platelets with arachidonate similar metabolites are formed, as demonstrated chromatographically. Infusion of imidazole (50-75 microgram/ml) through the lung or spleen specifically inhibits thromboxane A2 production and diverts the pathway to the prostaglandins, mainly prostaglandin F2alpha. In human platelets imidazole causes a dose-dependent inhibition of thromboxane A2 formation (ID50 5.5 X 10(-4) M). This inhibition is accompanied by a dose-dependent increase in prostaglandin F2alpha. Since thromboxane A2 induces platelet aggregation and is a potent vasoconstrictor, diversion of pathways to prostaglandins with opposite or less potent action might be of relevance in the treatment of cardiovascular diseases.

Animals↗
PubMed1977

Inhibition of histidine decarboxylase. Derivatives of histidine.

Twenty-eight derivatives of histidine were tested as inhibitors of histidine decarboxylase from rat stomach. Potent inhibition was observed with the methyl ester of L-histidine (1) which had a Ki = 1.8 X 10(-6) M. Substitution on 1 at various positions resulted in a decrease or complete loss of inhibition. Substituent requirements for inhibition of histidine decarboxylase are discussed. A simple disposable apparatus for the radiometric assay of histidine decarboxylase is described.

Animals↗
PubMed1977

Antidepressant drug therapy in psychotic depression.

Imipramine and phenelzine were ineffective in the treatment of five primary unipolar depressives with delusions, even when plasma levels of imipramine and desmethylimipramine or activity of platelet monoamine oxidase suggested that an adequate dose of drug had been given. Four patients went on to receive ECT and all responded well. Five non-delusional patients responded satisfactorily to the antidepressant drug given. Nine out of ten subjects were women. Non-delusional patients showed some placebo response. ECT is considered to be the treatment of choice in the acute phase of delusional depression in women.

Adult↗
PubMed1976

Biochemical properties of the prostaglandin/thromboxane synthetase of human blood platelets and comparison with the synthetase of bovine seminal vesicles.

The enzyme system which synthesizes prostaglandins and thromboxanes in extracts of washed human platelets has been characterized with respect to kinetic parameters, pH and cofactor dependence, and inhibitor potencies. Arachidonate and dihomo-gamma-linolenate were shown to be mutually competitive substrates, thus providing biochemical support for the assumption that both substrates are metabolized by the same cyclooxygenase, although they are ultimately metabolized to different patterns of products. Products of the synthetase of human leucocytes qualitatively resemble those obtained with human platelets. The prostaglandin synthetase of bovine seminal vesicles was studied under similar conditions, and kinetic parameters and inhibitor potencies were compared with those of platelet extracts.

Albumins↗
PubMed1976

Platelet monoamine oxidase activity in schizophrenia.

The activity of platelet monoamine oxidase in 12 chronic schizophrenic patients was not significantly different from that in a matched group of normal individuals. The authors emphasize the importance of simultaneous processing of control and patient blood samples and the use of carefully controlled techniques, since relatively minor changes in procedure can markedly influence platelet yield and leucocyte contamination.

Adult↗
PubMed1976

Red blood cell catechol O-methyl transferase and response to imipramine in unipolar depressive women.

When baseline red blood cell catechol O-methyltransferase (COMT) was measured in 15 unipolar depressive women, the authors found a linear correlation between COMT and response to imipramine (best outcome occurring at low COMT). The results of this study were not related to such variables as intensity of depression, family history, or psychiatric history. The authors suggest that this assay may be useful either as a predictor of response to the drug or as a guide in choosing the optimum dose.

Adult↗
PubMed1976

Catechol O-methyltransferase in red blood cells of schizophrenic, depressed, and normal human subjects.

Catechol O-methyltransferase of lysed human red blood cells was assayed under optimal conditions, using saturating concentrations of the substrates, S-adenosyl-L-methionine and 3-4-dihydroxybenzoic acid. The mean enzyme activity found in 24 normal subjects was 29-2 nmol/hr/ml RBC. The mean activity in blood of 33 female unipolar depressives was not significantly different from normal. However, higher enzyme activities were observed in the blood of 11 schizophrenic patients (38-9 nmol/hr/ml RBC). Partially purified enzyme preparations from blood of normal and schizophrenic individuals were indistinguishable with respect to substrate specificities, isoelectric pH values, and ratios of the two O-methylated products. Therefore it is unlikely that any defect in O-methylation which may occur in schizophrenia can be attributed to a change in the intrinsic properties of erythrocyte catechol O-methyltransferase.

Adult↗
PubMed1976

Potentiation of the anti-inflammatory and analgesic activity of aspirin by caffeine in the rat.

Caffeine has been found to potentiate the acute anti-inflammatory activity of aspirin, indomethacin, and phenylbutazone, but not the activity of sodium salicylate or hydrocortisone, in the carrageenan pleurisy or hindlimb models of inflammation in the rat. The mobilization of inflammatory cells was not affected by aspirin in the presence or absence of caffeine. The mild analgesia produced by aspirin was confined to a hyperalgesic test in which this drug was able to reduce inflammation and concomitant hyperalgesia and thereby produce an "apparent" analgesic effect. This "apparent" analgesia produced by aspirin was potentiated by caffeine. The mechanism responsible for the potentiated anti-inflammatory and mild analgesic activity of aspirin remains unknown since caffeine did not alter the plasma salicylate levels or prostaglandin synthetase inhibition produced by aspirin.

Animals↗
PubMed1975

Properties of catechol O-methyltransferases from brain and liver of rat and human.

Kinetic and electrophoretic properties of catechol O-methyltransferases (EC 2.1.1.6) from brain and liver were studied. The enzyme of either rat or human tissues exhibited a single molecular form when subjected to electrophoresis at pH7.9. At pH9 a second, apparently oxidized, form was detected. Isoelectric-focusing experiments also indicated only one enzyme form, which was identical from extracts of brain and liver of each species (pI = 5.2 for rat, 5.5 for human). Similarities between brain and liver catechol O-methyltransferase of a given species were also demonstrated by kinetic parameters, meta/para ratios of products, and inhibitor potencies. Human catechol O-methyltransferase exhibited lower Km values than did the rat enzyme for S-adenosyl-L-methionine, dopamine and dihydroxybenzoic acid. Adrenochrome inhibited both rat and human enzyme. It was concluded (1) that only a single enzyme form could be demonstrated in the physiological pH region; (2) that catechol O-methyltransferase of brain could not be distinguished from the liver enzyme of the same species; and (3) that species differences exist between the enzymes of rat and human tissues.

Adrenochrome↗