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Biomedical subjects

L Cohen

Publications and source records attributed to L Cohen.

At least 541 records · Page 30Linked to original sources
PubMed1978

Methylenetetrahydrofolate dehydrogenase-methenyltetrahydrofolate cyclohydrolase-formyltetrahydrofolate synthetase from porcine liver. Interaction between the dehydrogenase and cyclohydrolase activities of the multifunctional enzyme.

Methylenetetrahydrofolate dehydrogenase (5,10-methylenetetrahydrofolate: NADP+ oxidoreductase, EC 1.5.1.5) one of the activities of a trifunctional folate-dependent enzyme from porcine liver, uses an ordered kinetic mechannism as determined from initial velocity, product inhibition and dead-end inhibition studies. The final product released from the dehydrogenase is methenyltetrahydrofolate. However, from the time course of appearance of products it is observed that the methenyltetrahydrofolate, rather than equilibrating with the solution, is converted preferentially to formyltetrahydrofolate by the cyclohydrolase, (5,10-methenyletrahydrofolate 5-hydrolase (decyclizing), EC 3.5.4.9) demonstrating a functional interaction between these two enzymic activites.

Aminohydrolases↗
PubMed1978

Stimulus-governance and the hyperkinetic syndrome.

The hypothesis that hyperkinetic children are stimulus-governed was tested. In a sample of 39 nonmedicated hyperkinetic boys 26 were found to be stimulus-governed. In a control sample of 20 nonmedicated boys 6 were found to be stimulus-governed. An association was found between the hyperkinetic syndrome and stimulus-governance. The hypothesis is raised that response to methylphenidate is related to stimulus-governance. Several issues raised by the research are discussed.

Adolescent↗
PubMed1978

Significance of pyuria in urinary sediment.

Microscopic examination of the urinary sediment to determine the degree of pyuria is an accepted method to screen for urinary tract infection. We investigated the significance of pyuria in relation to the method of specimen acquistion, number of white blood cells and isolation of pathogens on culture. Only 36 per cent of our patients with more than 10 white blood cells per high power field on examination of the first random specimen had more than 10 white blood cells per high power field when a repeat clean catch midstream specimen was examined, and only 20 per cent of the patients had more than 10(5) pathogens per ml. on culture. However, the finding of more than 10 white blood cells per high power field on a clean catch mid stream specimen indicated more than 10(5) pathogens per ml. in 40 per cent of the cases. The use of a higher threshold for significant pyuria (more than 20 white blood cells per high power field) on examination of a random specimen increased the incidence of more than 10(5) bacteriuria found in specimens with initial pyuria by 43 per cent and represents the additional detection of 8.7 per cent of the total poputation studied. These data indicate that when screening for pyuria and infection one should either obtain a clean catch midstream specimen for examination of urinary sediment or increase the threshold for significant pyuria on a random specimen.

Adult↗
PubMed1978

Transformation of group F streptococci by plasmid DNA.

When the Challis strain of Streptococcus sanguis was transformed by the 17 megadalton beta plasmid from Streptococcus faecalis strain DS5, the plasmid underwent a 1.5 megadalton deletion (LeBlanc & Hassell, 1976). Furthermore, the covalently closed circular (CCC) plasmid DNA isolated from Challis transformants was rapidly converted to a linear form which did not possess any detectable transforming activity. To obtain stable CCC plasmid DNA a competent culture of a Lancefield group F streptococcus, strain DL8 (ATCC 12393), was used as a recipient of beta plasmid DNA. The plasmid DNA isolated from group F transformants exhibited the same configuration and size characteristics as the DS5 beta plasmid, and the CCC configuration was stable upon storage. CCC plasmid DNA from a group F transformant was biologically active and, when added to competent cultures of strain DL8, transformed them at frequencies about 100-fold greater than did beta plasmid DNA from DS5. This suggests the existence of a restriction--modification system in strain DL8.

DNA, Circular↗
PubMed1978

Perinatal mortality: assisting parental affirmation.

The health professional's role does not cease with perinatal death, but shifts towards the prevention of postmortem psychiatric sequelae in the parents. A multidisciplinary bereavement service has found that an increased awareness of the final processes of "viewing" and "burial" diminishes the production of fearful speculations both by parents and staff, and allows them to cooperate more fully in dealing with the tragedy.

Adaptation, Psychological↗
PubMed1978

Gentamycin serum levels in a patient with severe skin damage.

Pseudomonas aeruginosa grew in blood cultures taken from a 30-year-old woman with a 45% burn of second and third degree. Because of wound infection, skin grafting was unsuccessful and the wounds were left uncovered and treated topically with Eusol and saline solution. During this period 7 mg/kg gentamycin was administered to the patient daily; the blood level of the antibiotic was 3 microgram/ml, rather than the expected 8--12 microgram/ml in a patient without burns. On the eighth day, 40% of the administered dose was recoverable in the urine. With partial covering of the wounds, a dose of 5 mg/kg gentamycin daily gave blood levels of 6.5 microgram/ml. When most of the burn wounds were covered, a dose of 5 mg/kg gentamycin daily gave a blood level of 12 microgram/ml. Kidney function remained normal throughout the whole period. The possibility that gentamycin was eliminated through the burn wounds is suggested.

Adult↗
PubMed1978

A controlled study of Trancopal in sleep disturbances due to rheumatic disease.

A placebo controlled, double-blind study was carried out in six centres in general practice to assess the effectiveness of Trancopal in treating sleep disturbances due to rheumatic disorders. Eighty-five patients received a usual dose of two tablets of Trancopal or matching placebo at night for two weeks. Patients were assessed weekly and kept a daily record of the quality of sleep. All ratings showed that patients slept significantly better on Trancopal than on placebo. Day-time rheumatic stiffness however was not significantly reduced. Six patients receiving Trancopal reported side-effects chiefly drowsiness (five patients) which was controlled by dose reduction. It was concluded that for rheumatic patients Trancopal offers an acceptable alternative to current hypnotics over which it may prove to have some advantages, particularly for the elderly.

Adult↗
PubMed1978

Cell population kinetics and dose-time relationships for post-irradiation injury of the brachial plexus in man.

Collected data on radiation-induced lesions of the brachial plexus were analyzed on the assumption that this reaction arises from depletion of some unidentified cell population in the irradiated tissues. A multi-probit search program was used to derive best-fitting cell kinetic parameters in a composite multi-target model for cellular radiation lethality and repopulation. From these parameters, a comprehensive iso-effect table, for a wide range of treatment schedules including daily treatment as well as fractionation at shorter and longer intervals, was constructed. The table provides a useful set of tolerance dosage limits for late effects in irradiated peripheral nerve.

Brachial Plexus↗
PubMed1978

Calcium augmentation of enzyme leakage from mouse skeletal muscle and its possible site of action.

Creatine kinase efflux from isolated mouse skeletal muscle was monitored in the presence of various concentrations of Ca2+ or La3+ over a 5 hour period. Ca2+ levels between 10(-3) and 10(-2)M augmented enzyme leakage to greater than 300% above control. La3+, which is said to displace Ca2+ from sarcolemmal and t-tubule membranes, depressed enzyme efflux at concentrations between 10(-5) and 10(-3M. These data indicate that extracellular Ca2+ mediates in vitro enzyme efflux, and may be acting on the sarcolemma and its extensions. These observations may prove useful in developing new means to regulate enzyme leakage in various muscle disorders.

Animals↗