Biomedical subjects
Publications and source records attributed to M Evans.
A 10-year-old boy with a parathyroid ademona is reported. Parathyroid hormone estimations of samples obtained by selective jugular venous catheterization were useful in diagnosis and for localizing the tumour before operation.
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1. Acute administration of ethanol exerts a biphasic effect on the concentrations of rat brain tryptophan, 5-hydroxytryptamine and 5-hydroxyindol-3-ylacetic acid. Both effects are associated with corresponding changes in the availability of circulating free tryptophan. 2. The initial increases in the above concentrations are prevented by ergotamine, are unaltered by allopurinol and are potentiated by theophylline, whereas the later decreases are prevented by both ergotamine and allopurinol. 3. It is suggested that the initial enhancement by ethanol of brain tryptophan metabolism is caused by catecholamine-mediated lipolysis followed by displacement of protein-bound serum tryptophan, whereas the activation of liver tryptophaan pyrrolase, which is produced by the same mechanism, leads to the later decreases in the brain concentrations of tryptophan and its metabolites. 4. The initial effects of ethanol can be reproduced by an equicaloric dose of sucrose, and a comparison of the two treatments alone could therefore be misleading. 5. The effects of ethanol on liver and brain tryptophan metabolism have also been examined in mice, and a comparison of the results with those previously reported suggests that the ethanol effects are strain-dependent.
1. Liver tryptophan pyrrolase exists as holoenzyme and apoenzyme in rat, mouse, pig, turkey, chicken and possibly man. 2. The apoenzyme is absent from cat, frog, gerbil, guinea pig, hamster, ox, sheep and rabbit. 3. The hormonal mechanism of induction of the pyrrolase is absent from species lacking the apoenzyme. 4. The concentrations of tryptophan in livers and sera of these species are lower than in species possessing the apoenzyme. 5. Species lacking the apoenzyme or the hormonal induction mechanism have a deficient kynurenine pathway and are sensitive to the toxicity of tryptophan. 6. It is suggested that these species are not suitable as models for studying human tryptophan metabolism. 7. The possible significance of these findings in relation to veterinary and human neonatal care is discussed.
1. Chronic administration of glucose or nicotinamide in drinking water inhibits the activity of rat liver tryptophan pyrrolase, and subsequent withdrawal causes an enhancement. The enzyme activity is also inhibited by administration in drinking water of sucrose, but not fructose, which is capable of preventing the glucose effect. 2. The inhibition by glucose or nictinamide is not due to a defective apoenzyme synthesis nor a decreased cofactor availability. 3. The inhibition by nicotinamide is reversed by regeneration of liver NAD+ and NADP+ in vivo by administration of fructose, pyruvate or phenazine methosulphate. Inhibition by glucose is also reversed by the above agents and by NH4Cl. Reversal of inhibition by glucose or nicotinamide is also achieved in vitro by addition of NAD+ or NADP+. 4. Glucose or nicotinamide increases liver [NADPH]. [NADP+] is also increased by nicotinamide. [NADPH] is also increased by sucrose, but not by fructose, which prevents the glucose effect. Phenazine methosulphate prevents the increase in [NADPH] caused by both glucose and nicotinamide. 5. It is suggested that the inhibition of tryptophan pyrrolase activity by glucose or nicotinamide is mediated by both NADPH and NADH.
A modified version of Philpott's partogram was used to analyze primipara labor in Israel. The rate of cervical dilatation measure early in the active phase of labor (initial rate) is an accurate indicator of the outcome of labor. Ninety-three percent of primiparas with an initial cervical dilatation rate of 1.00 cm/hour or more delivered spontaneously. Seventy-six percent of those with an initial cervical dilatation rate of less than 1.00 cm/hour required an assisted delivery (forceps or vacuum) or cesarean section. The mean cervical dilatation rate for spontaneous deliveries as measured early in the active phase was 1.75 cm/hour. Patients needing an assisted delivery had a mean cervical dilatation rate of 0.93 cm/hour, and for cesarean section deliveries the mean rate was 0.42 cm/hour. No significant differences were observed among patients of different ethnic origins. The initial cervical dilatation rate proves to be useful in early identification of those patients who deliveries were complicated. The method avoids complicated cervicographs and is simple and reliable.
Antibiotic sensitivities of 15302 organisms of common pathogenic species isolated in one hospital pathology department in 1971 and 1974 have been studied. Resistance to cephaloridine did not change materially. The proportion of strains resistant to ampicillin did, however, increase, and this is attributed to the widespread therapeutic use of the antibiotic. Cephaloridine, on the other hand, was largely used in the hospital as a single-dose, intra-incisional prophylactic against surgical wound sepsis.
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In a randomized, controlled clinical trial of two methods of preventing postoperative leg vein thrombosis patients undergoing major surgery were divided into three groups. One received intermittent electrical calf muscle stimulation during surgery, the second subcutaneous heparin calcium 5000 IU every eight hours for six days, and the third no specific prophylaxis. Leg vein thrombosis was detected by the 125-I-fibrinogen uptake test. Neither method was effective in patients undergoing open bladder or prostatic surgery. Stimulation did not reduce the incidence of leg vein thrombosis in patients with malignant disease undergoing laparotomy, but heparin calcium was highly successful in this group (P smaller than 0-001). When the laparotomy was for a benign condition, however, both heparin calcium (P smaller than 0-001) and stimulation (P smaller than 0-01) were effective.
One hundred and ninety-two operation wounds ina general surgical practice were randomly allocated to receive either topical cephaloridine or a providone-iodine spray, and the rate of wound sepsis was studied. In all types of operation cephaloridine proved superior to providone-iodine as a prophylactic, the difference reaching a significant level in potentially contaminated wounds.
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Acute administration of nicotine hydrogen (+)-tartrate enhances the activity of rat liver tryptophan pyrrolase by a hormonal mechanism. Chronic nicotine treatment inhibits, and subsequent withdrawal enhances, the pyrrolase activity. The inhibition during chronic treatment is not due to a defective apoenzyme synthesis nor a decreased cofactor availability. Regeneration of liver NADP+ in vitro and in vivo reverses the inhibition. Chronic nicotine administration increases the liver NADPH concentration. The above effects of nicotine resemble to a remarkable degree those previously shown for morphine, phenobarbitone and ethanol. All effects are compared, and their possible significance in relation to drug dependence is discussed.
1. The administration of haematin or 5-aminolaevulinate to rat enhances the activity of liver tryptophan pyrrolase; both endogenous and newly formed apoenzymes become strongly haem-saturated. Haem activation does not stabilize tryptophan pyrrolase. 2. Actinomycin D, puromycin or cycloheximide prevent the activation of the enzyme by 5-aminolaevulinate but not that by haematin. The latter is inhibited by haem-destroying porphyrogens. 3. The combined injection of either haematin or 5-aminolaevulinate with cortisol does not produce an additive effect, whereas potentation is observed when tryptophan is jointly given with either the cofactor or the haem precursor. 4. Further experiments on the substrate (tryptophan) mechanism of pyrrolase regulation are reported, and a comparison between this and the cofactor and hormonal mechanisms is made. 5. It is suggested that the substrate mechanism may also involve increased haem synthesis. 6. The role of tryptophan pyrrolase in the utilization of liver haem, and as a possible model for the exacerbation by drugs of human hepatic porphyrias, is discussed.