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Biomedical subjects

L W Robertson

Publications and source records attributed to L W Robertson.

At least 109 records · Page 6Linked to original sources
PubMed1981

Aryl hydrocarbon hydroxylase (AHH) induction by polybrominated biphenyls (PBBs): enchancement by photolysis.

Irradiation of the commercial polybrominated biphenyl (PBB( mixture, fireMaster BP-6, in cyclohexane solution at 300 nm for 930 min resulted in a marked diminution of the major components of the mixture. Administration of the photolyzed PBB mixture of fireMaster BP-6 to immature male Wistar rats caused both dose-related decreases in thymus weight and increase in hepatic microsomal benzo[a]pyrene hydroxylase (AHH), 4-dimethylaminoantipyrine N-demethylase and NADPH-cytochrome c reductase activities and cytochrome P-450 content. The dose effecting half-maximal AHH induction for the photolyzed PBBs (9 mg . KG-1) was approximately 6 times lower than that of fireMaster BP-6 (50 mg. kg-1). Furthermore, the concentration of photolyzed PBBs (2 micrometers) required to displace 50% of the specifically-bound [3H] TCDD from its high-affinity cytosolic Ah receptor was approximately 150 times lower than that required for fireMaster BP-6 (300 micrometers), as measured by sucrose density gradient centrifugation analysis. The results suggest that the photolysis of the commercial PBB mixture yields products which possess increased biologic activity.

Animals↗
PubMed1980

Grand round series: hypoglycemia and unilateral pulmonary edema in a newborn.

A case of cardiomegaly with unilateral pulmonary edema is presented. The predisposing etiologies were severe hypoglycemia and a hypertonic glucose infusion into a branch of the left lower lobe pulmonary vein. Resolution resulted following maintenance of adequate glucose levels, vigorous cardiopulmonary support, and repositioning of the catheter tip in the inferior vena cava. The pathophysiologic mechanism was direct endothelial injury with an osmotic diuresis. The role of the release of a vasoactive substance was postulated.

Female↗
PubMed1978

Microbiological oxidation of the pentyl side chain of cannabinoids.

Syncephalastrum racemosum ATCC 18192 and Mycobacterium rhodochrous ATCC 19067 partially degrade the n-pentyl side chain of cannabidiol, cannabinol, delta8-tetrahydrocannabinol and delta9-tetrahydrocannabinol. Carboxylic acid and alcohol side chain derivatives are major metabolites.

Cannabinoids↗
PubMed1978

Successful intracardiac repair of the Taussig-Bing malformation in 2 children.

Surgical repair of the Taussig-Bing deformity has been successful in 2 children weighting 7.7 and 11.1 kg, respectively. In the first case the right ventricular patch divered left ventricular blood to the pulmonary arter, thus creating a physiologically complete transposition which was then corrected by an interatrial Mustard baffle. In the second case a right ventricular tunnel diverted left ventricular blood to the aorta, and right ventricular blood was directed to the distal pulmonary artery by means of an external conduit bypassing a subpulmonic stenosis. These patients represent the seventh and eighth successful corrections of the Taussig-Bing anomaly. One case (Patient 2) is the youngest to undergo repair and the first to receive an external conduit for bypass of an associated subpulmonic stenosis.

Age Factors↗
PubMed1977

Anatomic correction of transposition of the great arteries without significant ventricular septal defect or patent ductus arteriosus.

A case of transposition of the great arteries without a significant ventricular septal defect or patent ductus arteriosus was treated when the patient was 5 months of age by retransposition of the great arteries and coronary arterial supply to the appropriate ventricle. The patient has done well for 13 months, despite the late occurrence of aortic regurgitation.

Angiocardiography↗
PubMed1976

Fluttering of the interventricular septum. The result of truncal insufficiency.

We present a child with truncus arteriosus and truncal insufficiency who had diastolic fluttering of the anterior mitral valve leaflet and left ventricular surface of the interventricular septum on echocardiogram. Although the fluttering has been previously described in patients with aortic insufficiency, it has not been reported with truncus arteriosus.

Child↗
PubMed1975

Two antimicrobial alkaloids from heartwood of Liriodendron tulipifera L.

Alcoholic extracts of the heartwood of Liriodendron tulipifera have demonstrated antimicrobial activity against Staphylococcus aureus, Mycobacterium smegmatis, Candida albicans, and Aspergillus niger. The antimicrobial activity was associated only with the alkaloidal fraction. Separation of the active alkaloidal fraction by chromatography led to the isolation and identification of dehydroglaucine and liriodenine as the active components. Several other alkaloidal derivatives were prepared and tested. In addition to the active alkaloids, michelabine was also identified in the tertiary nonphenolic base fraction along with the lignan, lirioresinol-B-dimethyl ether, and two N-acetylnoraporphine alkaloids from the nonbasic fraction.

Alkaloids↗
PubMed1975

Correction of platelet dysfunction and bleeding in cyanotic congenital heart disease by simple red cell volume reduction.

Red cell volume reduction corrected the platelet aggregation abnormality and bleeding tendency in four boys, aged 5 to 16 years, with severe cyanotic congenital heart disease and polycythemia. Red cell volume was reduced by replacing 15 to 20 ml/kg body weight of the patient's blood with plasma in 50 ml increments over a 1 to 2 hour period. Within 3 days, platelet aggregation was restored essentially to normal, and previous bleeding symptoms disappeared. Platelet aggregation remained normal during 3 weeks of follow-up study and hematocrit values remained at palliative levels. The procedure was safe and simple, and it had beneficial effects not only on bleeding but also on other symptoms related to polycythemia. These preliminary observations suggest that red cell volume reduction may be useful preoperatively in patients with cyanotic heart disease and defects in platelet function to lessen the risk of serious bleeding during the early postoperative period. Palliation in severely cyanotic children whose condition is inoperable is another possible indication for this procedure.

Adolescent↗
PubMed1973

Some characteristics of tryptophan uptake in Claviceps species.

Tryptophan serves as a precursor for the biosynthesis of alkaloids in the ergot fungus, Claviceps purpurea (Fries) Tulasne, and also is believed to act as an inducer of the enzymes necessary for alkaloid production. The characteristics of the transport system responsible for the accumulation of tryptophan in ergot mycelium were investigated, with the goal of clarifying the complex relationships among tryptophan uptake, size of the free intracellular pool of tryptophan, and alkaloid production. The characteristics of tryptophan uptake were studied by pulse feeding radioactively labeled tryptophan to cultures of Claviceps species, strain SD-58, which represented a variety of ages and nutritional states. Tryptophan accumulation in strain SD-58 is mediated by an energy-requiring system which exhibits specificity for neutral aromatic and aliphatic l-amino acids, is pH and temperature dependent, and shows saturation at high substrate concentrations. Tryptophan transport is a function of the intracellular concentration of free tryptophan, the nitrogen deficiency of the mycelium, the rate of growth, and alkaloid production, which were measured in Claviceps strain SD-58 growth in several culture media, some of which promoted alkaloid production and some of which did not. The results indicate that the initial velocity of tryptophan transport is not directly related to alkaloid production.

Alkaloids↗
PubMed1972

Physiological studies on ergot: further studies on the induction of alkaloid synthesis by tryptophan and its inhibition by phosphate.

The failure of l-leucine to stimulate ergot alkaloid production in a synthetic medium indicates that the previously observed stimulation by tryptophan and tryptophan analogues does not merely represent a nutritional effect. Tryptophan, but not mevalonate or 5-methyltryptophan, is able to overcome the inhibition of alkaloid synthesis by high levels of inorganic phosphate. Therefore, high phosphate levels seem to limit the synthesis of tryptophan; they may, in addition, prevent induction of alkaloid synthesis by preventing accumulation of tryptophan. Experiments which indicate a 2- to 3-fold temporary increase of intracellular free tryptophan and a 20- to 25-fold increase of tryptophan synthetase activity during the transition period between growth and alkaloid production phase are in agreement with the previously postulated induction of alkaloid synthesis by tryptophan. The latter experiments also indicate 4- to 6-fold repression of this enzyme by tryptophan.

Amino Acids↗