Risk factors for relapse in health care professionals with substance use disorders.

Context: Substance use disorders among physicians are important and persistent problems. Considerable debate exists over whether use of major opioids, especially among anesthesiologists, is associated with a higher relapse rate compared with alcohol and nonopioids. Moreover, the risk factors for relapse with current treatment and monitoring strategies are unknown.

Vitamin effects on tryptophan-niacin metabolism in primary hepatoma patients.

Metabolism of 14C-labeled tryptophan and 3-hydroxyanthranilic acid were administered to early hepatoma patients to evaluate the conversion of these precursors to niacin metabolites and to assess the effect of dietary supplementation with vitamin B-6, riboflavin, thiamin and vitamin C on the extent of conversion. Expired labeled carbon dioxide and urinary excretion of picolinic acid (PA), quinolinic acid (QA), nicotinic acid (NA), N1-methylnicotinamide (N1MeNAm) and N1-methyl-2-pyridone-5-carboxamide (MPCA) were measured by carrier isolations. There were no consistent statistical differences in these conversions before and after vitamin supplementation, suggesting that the patients' nutrition was adequate and that none of the vitamins were rate-limiting under these conditions.

Effect of Huntington's and Alzheimer's diseases on the transport of nicotinic acid or nicotinamide across the human blood-brain barrier.

The cerebral uptake of 11C-nicotinic acid (11C-NAC) and 11C-nicotinamide (11C-NAM) was quantified by the use of PET. Based on the amount of activity injected, the PET images showed a low cerebral uptake of 11C-NAC, while 11C-NAM was clearly visualized in the cortical areas. This discrepancy was found to be the result of the binding of 11C-NAC to the red blood cells by a factor of 5 to 20 above that for 11C-NAM.