Biomedical subjects
Publications and source records attributed to D J Edwards.
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To understand the biological significance of a decreased platelet MAO activity in schizophrenia, it is important to answer many questions about the basic molecular properties of the enzyme. The past decade has witnessed a huge expansion of research in this area which has provided some of these answers. A wide variety of experimental evidence strongly supports the concept of two forms of MAO (types A and B) that are present in most tissues but in varying relative amounts. However, human platelets contain only the type B form of MAO. This review discusses what is known about the molecular properties of MAO, what questions remain unresolved, and the significance of both the answered and unanswered questions to understanding the measurement of platelet MAO activity in schizophrenic patients.
This study compares the minimum inhibitory concentrations of cefoperazone, cefotaxime, and moxalactam (LY127935) for 446 aerobic gram-negative bacillary isolates and further compares the minimum inhibitory concentrations of LY127935 and these third-generation cephalosporins with those of thienamycin for Pseudomonas aeruginosa. Each antibiotic at low concentrations inhibited nearly all Enterobacteriaceae tested. Minimum inhibitory concentrations for P. aeruginosa were higher, but for a majority of strains they fell below achievable serum levels. Thienamycin and cefoperazone showed significantly greater antipseudomonal activity than did cefotaxime or LY127935. Cefoxitin-inducible resistance to LY127935 and the two cephalosporins was demonstrated among Enterobacter species but did not occur with thienamycin.
Glucose limited the maximum population density of the cell line Bri 8 over a wide range of pH values. Efficiency of glucose utilisation varied with pH and hence pH influenced maximum population density. Surprisingly the ratio of glucose consumed to lactic acid produced was not greatly influenced by pH.
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We have found that 2,6-dinitro-4-trifluoromethylbenzenesulfonic acid reacts rapidly and specifically with primary amines at room temperature. We have used this reagent for derivatizing phenylethylamines, including catecholamines, and histamine and 1-methylhistamine. After the reaction, hydroxyl groups were derivatized to form the corresponding trimethylsilyl ethers, and the final derivatives were analyzed by gas chromatography with electron-capture detection. These derivatives are stable, possess excellent gas chromatographic properties and are detected with high sensitivity. We have applied this method to the analysis of histamine and 1-methylhistamine in human urine.
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Phenylethylene glycol has been identified in rat and human urine using gas chromatography/chemical ionization/mass spectrometry. A method was developed for the quantitative analysis in urine of this phenylalanine metabolite and of p-hydroxyphenylethanol, a metabolite of tyrosine, by converting them to the pentafluoropropionyl derivatives and measuring them by selected ion monitoring. In human urine, about 90% of the phenylethylene glycol was present in a conjugated form (releasable by glusulase), but the reverse was true for rat urine, with about 90% being present in the unconjugated form. The excretion of free phenylethylene glycol (expressed as ng/mg creatinine) was 2.7-fold higher in a group of untreated phenylketonuric patients than in the control group, but the phenylketonuric patients excreted abnormally low amounts of 3-methoxy-4-hydroxyphenylethylene glycol. Intraperitoneal injections of L-phenylalanine in rats resulted in a small increase in the excretion of phenylethylene glycol. On the other hand, the injection of phenylethanolamine resulted in an 82-fold increase in the excretion of phenylethylene glycol, but phenylethylamine had no effect. These results indicate that the conversion of phenylethylamine to phenylethanolamine is the rate limiting step in this metabolic pathway.
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Platelet monoamine oxidase (MAO) activity and electroencephalographic (EEG) sleep measures were examined in 56 drug-free hospitalized patients with primary depression as defined by the Research Diagnostic Criteria. The group included 35 females and 21 males with a mean age of 42.6 +/- 1.4 years. Platelet MAO and EEG sleep data were compared for the group as a whole and separately for the unipolar, bipolar, male, and female subgroups. No significant relationships could be demonstrated for the entire group or for the unipolar, male, or female subgroups. However, an inverse relationship between MAO activity and REM sleep percent was noted in the bipolar subgroup (p < 0.02). While changes in REM sleep have been relatively firmly established in primary depression, the relationship of MAO to depression and to REM sleep remains unclear.
Swine serum is an inexpensive substitute for foetal calf serum for lymphocyte culture. It gives an increased yield of Ig from 1788 cells and permits the large scale production of cells for Ig mRNA isolation.
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Platelet monoamine oxidase (MAO) activity was determined with tryptamine as substrate for 61 drug-free patients who had a primary major depressive disorder and for 32 normal controls. Although there were no significant differences between the mean platelet MAO activity of 19 bipolar patients (4.94 nmoles/hr/mg of protein), 42 unipolar patients (4.97 nmoles), and the controls (4.78 nmoles), an analysis of variance indicated that the variance of the bipolar group was significantly greater than that of the other groups. This suggests that there may be subgroups of bipolar patients that differ in their platelet MAO activity but that appear to be distinct from the bipolar I vs bipolar II classification.