Inhibition of yeast respiration and fermentation by benomyl, carbendazim, isocyanates, and other fungicidal chemicals

The inhibition of yeast (Saccharomyces cerevesiae) metabolism by fungicidal chemicals was investigated. Glucose- or ethanol-dependent yeast respiration was measured with an oxygen electrode, and manometric determination of carbon dioxide release was used to measure fermentation. Both respiration and fermentation were inhibited more by benomyl than by identical molar concentrations of its breakdown product, carbendazim. Butyl isocyanate, another benomyl breakdown product, inhibited respiration more but inhibited fermentation less than the parent compound. Of the isocyanates tested, hexyl isocyanate was the most inhibitory towards both activities. Captan was more active and iprodione less active than benomyl. Because benomyl rapidly broke down to carbendazim when it was prepared in 80% ethanol, only 59% of the dissolved benomyl was intact when it was added to yeast to determine its effect on respiration or fermentation.

Cerebrospinal Fluid Dynamics in Patients with Pseudotumor Cerebri

CSF dynamics were determined as a function of intracranial pressure in patients with pseudotumor cerebri. Servocontrolled variable rate lumbar infusions were used to determine net CSF-absorptive capacities and resting pressures in 10 patients; serial studies were done in 5 of the patients. Nearly all of the patients had abnormally low CSF-absorptive capacities. On the other hand, marked elevations in resting pressure were not a constant feature of the disease. Concurrent changes in the cerebrovascular bed could introduce errors into this manometric determination of CSF dynamics; the significance of this potential artifact is examined. The results of this study suggest that the CSF compartment may be of etiological importance in the pathophysiology of pseudotumor cerebri.

A manometric determination of nitrogen in small samples of blood. Application to measurement of arterial–alveolar nitrogen difference in man

Arterial–alveolar nitrogen [Formula: see text] gradients in man can be obtained from a 3- to 4-ml sample of venous blood. The method described measures the nitrogen content in a 1-ml sample of blood by use of a slightly modified Natelson microgasometer equipped with automatic shakes. The values obtained are accurate and confirm those reported by others using macro-volumetric or gas chromatography techniques.