Partial characterization of the phosphotransferase system of human central-nervous-system myelin.

The phosphotransferase system of human central-nervous-system myelin was investigated. Evidence obtained indicated the presence of at least two different phosphotransferase systems (cyclic nucleotide-dependent and -independent) in myelin, which were found to be firmly associated with the membrane. The cyclic AMP-dependent kinase of myelin and white-matter cytosol preferentially phosphorylated certain histone fractions and displayed only modest activity with basic protein as substrate. On the other hand, the cyclic nucleotide-independent system showed specificity toward basic protein. Its activity was not only dependent on Mg2+ but it was greatly enhanced by this bivalent cation. Whereas the cyclic nucleotide-dependent kinase could be extracted with buffers containing Triton X-100, the bivalent cation-regulated kinase resisted solubilization from myelin under these conditions.

Enzyme activities in human endometrium, myometrium and leiomyomas of the uterus.

Certain selected enzymes of carbohydrate metabolism were measured in samples of endometrium and myometrium from women who were premenopausal or postmenopausal. In addition, a number of samples of leiomyoma were obtained and assayed. Activities of several enzymes were higher in endometrium from premenopausal women compared to those in postmenopausal women; activities in myometrium were similar regardless of menopausal status. The activities of G6PD, ICD and GPI appeared to be lower in leiomyoma samples versus myometrial samples from premenopausal women; however, these differences were not apparent when enzyme activity was expressed per milligram protein.

Relationship of glycolytic enzyme activities and response of breast cancer patients to chemotherapy: A preliminary report.

Activities of glucosephosphate isomerase, lactate dehydrogenase, and NADP-isocitrate dehydrogenase were significantly elevated in breast cancer specimens from patients who responded favorably to combination cytotoxic chemotherapy regimens compared with those in carcinomas from patients failing to respond to the same chemotherapy. Presence of estrogen receptors and clinical response to hormonal therapy were also evaluated in neoplasms from these patients. The data suggest that measurement of the enzyme profile, along with estrogen receptor levels, may be useful in selecting a mode of therapy for patients with advanced disease.

Multiple molecular forms of lactate dehydrogenase and glucose 6-phosphate dehydrogenase in normal and abnormal human breast tissues.

Normal and abnormal breast samples of women were analyzed for multiple molecular forms of lactate dehydrogenase and glucose 6-phosphate dehydrogenase, using acrylamide disc gel electrophoresis and specific enzyme staining techniques for separation and quantitation. Infiltrating ductal carcinomas demonstrated a significant increase (three to six-fold) in the proportion of LDH-5 compared to samples of normal breast, fibrocystic disease and fibroadenoma, indicative of a shift toward the muscle-type lactate dehydrogenase in neoplasia. For glucose 6-phosphate dehydrogenase, carcinomas were found to contain increased proportions of the fastest migrating species, G6PD-I. Total enzyme activity/mg DNA was elevated in meoplastic tissues. Little or no alteration in isoenzyme profiles could be related to menopausal status of the patient.