Cytogenetic studies in rats of cyclohexylamine, a metabolite of cyclamate

Cyclohexylamine, the major known metabolite of cyclamate, was tested in vivo for possible cytogenetic effects. In rats injected with this metabolite, there was a direct relation between dose concentration and percentage of spermatogonial and bone marrow cells showing chromosomal breaks. Single chromatid breaks predominated with infrequent exchange figures.

Behavior of the NO-beta-D-glucosiduronic acid of N-acetyl-N-phenylhydroxylamine as a substrate for beta-glucuronidase

1. Biosynthetic sodium (N-acetyl-N-phenylhydroxylamine NO-beta-d-glucosid)-uronate is hydrolysed completely by purified mouse urinary beta-glucuronidase into the products N-acetyl-N-phenylhydroxylamine and glucuronic acid. The hydrolysis is inhibited by saccharo-(1-->4)-lactone. These results not only confirm the identity and purity of the substrate but also establish it as a substrate for beta-glucuronidase. 2. Mammalian and bacterial beta-glucuronidase preparations hydrolysed the substrate at a rate one-fifth of that for (phenolphthalein beta-d-glucosid)uronic acid under the optimum conditions of hydrolysis for each source. 3. The pH optimum is 4.1 and the Michaelis constant, K(m), is 3.3x10(-4)m with purified mouse urinary beta-glucuronidase as the enzyme source acting on the NO-beta-d-glucosiduronic acid. The aglycone after extraction into chloroform was quantitatively determined spectrophotometrically at its absorption maximum (256mmu). 4. The hydrolysis was studied as a function of time and temperature. 5. From a consideration of the chemical and enzymic properties of this NO-beta-d-glucosiduronic acid it is possible to suggest its catabolism in vivo.

Auditory sensitivity of the monkey

Auditory thresholds for pure tones were determined in monkeys (three Macaca irus and one Macaca nemestrina) by the psychophysical method of constant stimuli after the animals had been trained by operant conditioning procedures. Their audible frequency range was found to extend from below 60 hertz to 40 or 45 kilohertz.