No abstract

Polyamine levels and the activities of two polyamine biosynthetic enzymes, arginine decarboxylase (EC 4.1.1.19) and S-adenosylmethionine decarboxylase (EC 4.1.1.50), were determined during somatic embryogenesis of carrot (Daucus carota L.) cell cultures. Embryogenic cultures showed severalfold increases in polyamine levels over nondifferentiating controls. A mutant cell line that failed to form embryos but grew at the same rate as the wild-type line also failed to show increases in polyamine levels, thus providing evidence that this increased polyamine content was in fact associated with the development of embryos. Furthermore, inhibition of these increases in polyamines caused by drugs inhibited embryogenesis and the effect was reversible with spermidine. The activities of arginine decarboxylase and Sadenosylmethionine decarboxylase were found to be suppressed by auxin; however, the specific effects differed between exogenous 2,4-dichlorophenoxyacetic acid and endogenous indole-3-acetic acid. The results indicate that increased polyamine levels are required for cellular differentiation and development occurring during somatic embryogenesis in carrot cell cultures.

Eleven of twelve human breast cancers contained a lipid which increased urinary (45)Ca and (40)Ca excretion of (45)Ca-labeled, parathyroidectomized rats receiving a low Ca diet. The lipid has mobility on thin-layer chromatography and gas-liquid chromatography close to, but not identical with, that of 7-dehydrocholesterol. Authentic 7-dehydrocholesterol has osteolytic activity similar to that of the extracted sterol. Fluorescence and Lieberman-Burchard reactions of the extracted sterol are similar to those of 7-dehydrocholesterol. The lipid was found by thin-layer chromatography in the extracts which had osteolytic activity. Neither the lipid nor osteolytic activity was found in extracts of tissue from two normal human breasts.

An earlier study that showed the importance of cerebrospinal fluid polyamine levels for monitoring patients harboring medulloblastomas was expanded to 210 determinations evaluated in 32 patients. The results and conclusions of our earlier study have been confirmed in this expanded patient group. Patient status, with regard to either progression or regression of tumor, was determined by correlating polyamine levels with neurologic examination, computerized tomography, radionuclide scan, cerebrospinal fluid cytology, and myelography. The polyamine assay was predictive of recurrence in 15 patients; three false negatives and no false positives were found. We feel that cerebrospinal fluid polyamine determinations should be a routine diagnostic procedure in the long-term monitoring of patients harboring medulloblastoma.