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J Seidenfeld

Publications and source records attributed to J Seidenfeld.

45 records · Page 3Linked to original sources
PubMed1981

Sensitization of 9L rat brain gliosarcoma cells to 1,3-bis(2-chloroethyl)-1-nitrosourea by alpha-difluoromethylornithine, an ornithine decarboxylase inhibitor.

alpha-Difluoromethylornithine, a known inhibitor of polyamine biosynthesis, significantly enhanced the cytotoxic effect of 1,3-bis(2-chloroethyl)-1-nitrosourea, a cell cycle-nonspecific agent, in 9L rat brain gliosarcoma cells in vitro. Administered as a single agent, alpha-difluoromethylornithine was not cytotoxic to 9L cells and, compared to untreated control cells, caused no perturbation of cell cycle kinetics. alpha-Difluoromethylornithine-induced depletion of intracellular polyamine levels appears to have caused the observed sensitization of 9L cells to 1,3-bis(2-chloroethyl)-1-nitrosourea. Restoration of intracellular polyamine levels by the addition of exogenous putrescine to treated 9L cells reversed this phenomenon.

Animals↗
PubMed1980

Effects of DL-alpha-methylornithine on proliferation and polyamine content of 9L rat brain tumor cells.

Treatment of 9L rat brain tumor cells with 10 mM DL-alpha-methylornithine (alpha MO) resulted in cytostasis when cells were plated in monolayer culture at an initial cell density of 5 x 10(5)/flask but not 1 x 10(6). Fifty mM caused cytostasis at both initial densities but more effectively at the lower one. Cytocidal effects measured by a colony-forming efficiency assay were observed at 100 mM but not at 75 mM or less. Both concentrations at both initial cell densities depleted intracellular putrescine content to less than 5% of control by 12 hr and spermidine content to less than 20% of control by 48 hr posttreatment. Intracellular spermine content increased between 1.5- and 2-fold with either concentration of alpha MO and at both densities. Flow cytometry revealed no differences in cell cycle distribution between controls and cells treated with 10 mM alpha MO. The cytostatic effect of 10 mM alpha MO on 9L cultures of lower initial density appeared to be a specific result of polyamine depletion since it was reversible by exogenous putrescine added 24 hr after treatment. The effect of 50 mM alpha MO was not reversible by exogenous putrescine or pyridoxal added simultaneously or 24 hr after treatment. Treatment of 9L cells with 50 mM DL-or L-ornithine caused growth inhibition equal to that produced by 50 mM alpha MO. The effect of 50 mM alpha MO is thus not attributable to polyamine depletion.

Animals↗
PubMed1979

Biochemical markers of central nervous system tumors measured in cerebrospinal fluid and their potential use in diagnosis and patient management: a review.

The concept of tumor markers was reviewed, and the potential uses of markers of central nervous system (CNS) tumors and methods for their evaluation were discussed. Markers examined included lactate dehydrogenase, aspartate aminotransferase, fructose-bisphosphate aldolase, the polyamines, desmosterol, and several other enzymatic, nonenzymatic, and immunologic markers. Data collated from the clinical studies surveyed showed isocitrate dehydrogenase, desmosterol, and the polyamines to have the greatest potential utility in the diagnosis of CNS tumors.

Antigens, Neoplasm↗