Effect of different levels of oral pyridoxine supplementation on plasma pyridoxal-5'-phosphate and pyridoxal levels and urinary vitamin B-6 excretion

Plasma pyridoxal-5'-phosphate and pyridoxal levels increased significantly (p less than 0.05) when single, oral bolus doses of pyridoxine were increased from 10 to 25 and from 25 to 50 mg in nine female volunteers. However, when the dose was increased to 100 mg, plasma pyridoxal-5'-phosphate levels did not differ significantly from those recorded after the 50 mg dose. Within 3 h plasma pyridoxal levels rose with a factor of 3.85 compared with the 50 mg dose but high pyridoxal levels were eliminated from the circulation. Renal clearance of pyridoxal remained a constant, low percentage (less than 2.0%) of each pyridoxine supplement in spite of the observed very high circulating pyridoxal levels. Pyridoxine supplementation is discussed in relation to circulating pyridoxal-5'-phosphate and pyridoxal availability for cellular metabolism.     

A measurement of the efficacy of nosocomial infection control using the 95 per cent confidence interval for infection rates

From 1981 through 1985, the authors studied the changes in monthly nosocomial infection rates at the University of Virginia Hospital in Charlottesville, Virginia using the 95% confidence interval for infection rates as a marker of the efficacy of infection control activities. For a 99-month baseline period, monthly infection rates were calculated and the 95% confidence interval was established. In the 60 study months, each monthly rate was compared with the 95% confidence interval for that particular month. At the end of each study year, the monthly infection rates were incorporated into the existing confidence interval. Of 60 monthly rates during the study period, 30 were below the confidence interval (p less than 0.00001), two were above the confidence interval (p = 0.23), and 28 were within the confidence interval. Since there was no reduction in surveillance activity, patient case-mix index, or laboratory sensitivity for organism recovery, these results suggest that monthly nosocomial infection rates at this hospital have decreased when compared with the baseline period. The use of the 95% confidence interval may provide a measure of the efficacy of infection control activities, suggest temporal intervals requiring more intensive infection surveillance, and provide a method for examining the variability in monthly infection rates.     

Radiation-induced meningioma. 3 cases

During the same year (1984), we have seen 3 cases of meningiomas following radiation therapy of the brain for previously diagnosed tumors. A causal relationship between irradiation and meningioma has been postulated. Nevertheless, the coincidental occurrence in same patient of two different histological lesions is possible. The neoplasms developed after irradiation are of mesenchymal origin; they are fibrosarcomas, osteogenic sarcomas and meningiomas.     

Effect of age and diet on cyclic nucleotide concentrations in the intestinal mucosa of developing rats

Mucosa isolated from the proximal third of the small intestine of infant rats had much lower cyclic nucleotide concentrations (expressed both per unit wet weight and per unit DNA content) than those determined in the intestinal wall. The steady-state concentrations of both cyclic AMP and cyclic GMP in jejunum showed dramatic increases during the first 5 d post partum. Another increase in cyclic nucleotide concentrations was observed in the isolated mucosa between d 15 and 21. Starvation for 24 h always resulted in lower intestinal cyclic nucleotide concentrations than those of the fed littermates. This effect was more pronounced in younger animals and more evident for cyclic AMP values. Three-week-old rats fed a high carbohydrate diet for 24-48 h exhibited more pronounced elevations in the concentrations of cyclic nucleotides from the jejunal mucosa than did rats fed a high fat diet.     

Permeation of chemical protective clothing by three binary solvent mixtures

An evaluation of glove materials against three different binary chemical mixtures selected from common industrial solvents was conducted. Changes in breakthrough time and permeation rate of the mixture components were evaluated as a function of the mixture composition. An increase in employee risk resulting from early mixture breakthrough time and enhanced mixture permeation rate over that of the pure chemicals was demonstrated. The permeation of a binary mixture through chemical protective clothing could not be predicted by the permeation results of the pure components. It is recommended that chemical protective clothing be tested for its permeation characteristics with the use of the chemical mixtures and conditions that reflect the work site exposure.     

The simultaneous determination of chloroformates and phosgene at low concentrations in air using a solid sorbent sampling--gas chromatographic procedure

A method was developed for the simultaneous determination of a number of reactive chloroformates and phosgene in air at low concentration levels. The procedure utilized the collection of air containing these contaminants on a di-n-butylamine-coated solid adsorbent. After samples were taken, the carbamate and urea derivatives were desorbed with hexane, washed with 1N HCl and analyzed by gas chromatography with flame ionization detection. The procedure provided an accurate exposure level for each of the desired compounds on a time-weighted average basis. Average recovery efficiencies ranged from 98% to 106%, with an average detection limit of 0.7 micrograms or 0.08 ppm v/v in 1.5 L of air. More recent tests have extended the use of the technique to include carboxylic acid chlorides--specifically, pivalic acid chloride and 3-chloropivalic acid chloride. The average recovery efficiency for these compounds was 69%.     

Exposure to formaldehyde and cancer mortality in a cohort of workers producing resins

The mortality of 1,332 male workers employed at least 30 days in 1959-1980 in a resins-manufacturing plant was examined. Ambient measurements taken in the plant between 1974 and 1979 documented a potential for exposure to levels of formaldehyde as high as greater than 3.0 mg/m3. Vital status was ascertained for 98.6% of the cohort members, and their mortality was compared with expected deaths drawn from the national and local population rates. A statistically significant increase in lung cancer was observed, based on 18 deaths, which was not fully accounted for by possible confounding factors linked to personal habits or sociocultural characteristics. This elevated risk, however, could not be attributed specifically to exposure to formaldehyde. Mortality from digestive cancer (14 deaths observed) and hematologic neoplasms (5 deaths observed) was not substantially higher than expected. The study was limited by information bias due to incomplete work histories, by the small number of deaths from some relevant causes, and by the possibly insufficient length of the observation period. Therefore these results do not provide sufficient grounds either to link formaldehyde exposure in the plant to the increased cancer risk noted or to exclude that formaldehyde might pose such a risk to humans under certain exposure circumstances.