Quantification of salicylate in serum by use of salicylate hydroxylase.

In this enzymatic method for salicylate in serum, Pseudomonas salicylate hydroxylase (EC 1.14.13.1) is used. This stable enzyme catalyzes the stoichiometric, unidirectional conversion of salicylate and NAD(P)H to catechol and NAD(P)+ in the presence of molecular oxygen. The concentration of salicylate in a clinical sample is determined by measuring the delta A at 340 nm as compared with a standard. This new method is rapid, highly specific, requires 40 microL or less of sample, and we saw no interference by any of 61 commonly used drugs. Lipemic, icteric, or hemolyzed samples can be used. Furthermore, this method does not involve extraction, deproteinization, or derivatization. Results are precise and agree well with those obtained by the Trinder test.

Toluene blood level following subcutaneous injection of toluene in the rat.

A model of toluene level in blood following subcutaneous injection of toluene mixed with polyoxyethylated-vegetable-oil vehicle was developed. The purpose was to provide a means of predicting dose received for subsequent toxicologic studies for any time and dose combination. The pharmacokinetics were of secondary interest. Using data from 111 rats, a four-parameter equation was devised to predict the time course of toluene blood level from 20-480 min post dosing, for dose levels of 50-1000 mg/kg. Blood concentrations rose at a rate which was independent of dose level. Maximum blood levels were uniquely determined by dose level. Blood levels fell at different rates depending upon dose level. Injection exposure, when compared to inhalation, has the advantages of (a) low expense, (b) low equipment requirements, and (c) simplicity. The disadvantage is, for some experiments, poor temporal stimulation of the normal route of administration, inhalation.

Microenvironmental exposure to mercury vapor.

Work area and breathing zone samples were collected in a factory utilizing metallic mercury and analyzed for mercury vapor content. Breathing zone samples averaged several fold higher in concentration than concurrent area samples, reflecting a "microenvironmental" exposure to mercury vapor, presumably from contaminated clothing and hands. Blood and corrected total urine mercury values correlated well with the average microenvironmental exposure level for each worker. Measurements of unbound mercury in urine samples were sensitive at picking up minimal exposures. Excessive amounts of unbound mercury were not found in the urine, even with wide day-to-day swings in microenvironmental mercury vapor levels, suggesting that the human body can adapt to a chronic, moderate exposure to mercury vapor.