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001-es BibID:	BIBFORM006026
Első szerző:	Basu, Hirak S.
Cím:	Effect of polyamine depletion on chromatin structure in U-87 MG human brain tumour cells / Basu, H. S., Sturkenboom, M. C., Delcros, J. G., Csokan, P. P., Szollosi, J., Feuerstein, B. G., Marton, L. J.
Dátum:	1992
Megjegyzések:	The chromatin structure of polyamine-depleted U-87 MG human brain tumour cells was studied by following the kinetics of digestion of cell nuclei by micrococcal nuclease and bovine pancreatic DNAase I. Cells growing in monolayers were treated with either alpha-difluoromethylornithine (DFMO), to deplete putrescine and spermidine, or N1,N14-bis(ethyl)homospermine (BE-4-4-4), to deplete putrescine, spermidine and spermine. BE-4-4-4 increased the initial rates of digestion and the magnitudes of limit digest by both enzymes; DFMO increased the limit digests without affecting initial digestion rates. Addition of 1 mM-putrescine 1 day after addition of DFMO reversed the effect of DFMO on limit digests. (Because polyamine uptake is low in cells treated with BE-4-4-4, and because putrescine does not reverse the growth-inhibitory effects of BE-4-4-4, reversal of the effects of BE-4-4-4 with putrescine was not attempted.) The increases in initial rates and limit digests did not result from changes in the lengths of nucleosomal or linker DNA, from blocks in cell-cycle progression, or from growth inhibition caused by DFMO or BE-4-4-4. Thus, because the limit digest is highest in cells with the lowest polyamine levels, it seems clear that the enhanced enzymic digestion of nuclei is caused by polyamine depletion and its possible effect on chromatin structure.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban folyóiratcikk analogs and derivatives Brain Neoplasms Cell Cycle Cell Nucleus Chromatin Culture Media Culture Media,Serum-Free Deoxyribonuclease I Dna drug effects Eflornithine Enzymes Human Intracellular Fluid Kinetics metabolism Micrococcal Nuclease pathology pharmacology Polyamines Putrescine Spermidine Spermine Support,Non-U.S.Gov't Support,U.S.Gov't,P.H.S. Tumor Cells,Cultured ultrastructure
Megjelenés:	The Biochemical Journal. - 282 : Pt 3 (1992), p. 723-727. -
További szerzők:	Sturkenboom, M. C. Delcros, J. G. Csokan, P. P. Szöllősi János (1953-) (biofizikus) Feuerstein, Burt G. Marton, Laurence J.
Internet cím:	elektronikus változat
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001-es BibID:	BIBFORM006032
Első szerző:	Delcros, J. G.
Cím:	Differential effects of spermine and its analogues on the structures of polynucleotides complexed with ethidium bromide / Delcros J. G., Sturkenboom M. C., Basu, H. S., Shafer R. H., Szöllösi, J., Feuerstein, B. G., Marton, L. J.
Dátum:	1993
Megjegyzések:	The interactions of spermine and polyamine analogues with synthetic polynucleotides of various base sequences complexed with ethidium bromide (EB) were investigated using measurements of fluorescence intensity and steady-state fluorescence polarization. Spermine and polyamine analogues displaced some but not all of the EB bound to poly(dA-dT).poly(dA-dT) or poly(dG-dC).poly(dG-dC), suggesting that polyamines may stabilize these polynucleotides in a conformation with reduced affinity for EB. Modifications of the aliphatic backbone of spermine have pronounced effects on its ability to displace EB from poly(dA-dT).poly(dA-dT) but not from poly-(dG-dC).poly(dG-dC). Spermine and some but not all of the polyamine analogues caused fluorescence depolarization when they interacted with the complex of EB and poly(dA-dT).poly-(dA-dT). Neither spermine nor any of the analogues, however, induced fluorescence depolarization in the complex of EB with poly(dG-dC).poly(dG-dC) or poly(dA).poly(dT). This suggests that spermine and some spermine analogues induce structural changes specific to alternating A-T sequences.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban folyóiratcikk chemistry Ethidium Fluorescence Fluorescence Polarization Nucleic Acid Conformation pharmacology Poly dA-dT Polyamines Polydeoxyribonucleotides Polynucleotides Spectrometry,Fluorescence Spermine Support,Non-U.S.Gov't Support,U.S.Gov't,P.H.S.
Megjelenés:	The Biochemical Journal. - 291 : Pt 1 (1993), p. 269-274. -
További szerzők:	Sturkenboom, M. C. Basu, Hirak S. Shafer, R. H. Szöllősi János (1953-) (biofizikus) Feuerstein, Burt G. Marton, Laurence J.
Internet cím:	elektronikus változat
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001-es BibID:	BIBFORM006033
Első szerző:	Feuerstein, Burt G.
Cím:	alpha-Difluoromethylornithine alters calcium signaling in platelet-derived growth factor-stimulated A172 brain tumor cells in culture / Feuerstein, B. G., Szollosi, J., Basu, H. S., Marton, L. J.
Dátum:	1992
Megjegyzések:	alpha-Difluoromethylornithine (DFMO), an irreversible inhibitor of the polyamine biosynthetic enzyme ornithine decarboxylase, inhibits the growth of brain tumor cell lines and is undergoing clinical trials as a treatment for brain tumors. Platelet-derived growth factor (PDGF) is thought to regulate the growth and development of precursors of both normal and neoplastic astrocytic cells; calcium signaling is thought to play a role in the transduction of PDGF signals. Using laser fluorescence image cytometry, flow cytometry, and spectrofluorometry, we studied the effect of DFMO on the calcium signals induced by PDGF in A172 human glioblastoma cells. Four days of treatment with 5 mM DFMO substantially shortened PDGF-induced calcium signals. The effect was reversed more than 10 h but less than 24 h after putrescine treatment, even though polyamines were repleted 4 h after putrescine and spermidine were added. DFMO did not substantially affect intracellular calcium release or the timing of the opening and closing of plasma membrane calcium channels. These findings support the notion that calcium signaling may be a target for inhibitors of polyamine metabolism.
Tárgyszavak:	Orvostudományok Elméleti orvostudományok idegen nyelvű folyóiratközlemény külföldi lapban analysis Biogenic Polyamines Brain Neoplasms Calcium Calcium Channels Calcium Signaling Cell Line drug effects Eflornithine Flow Cytometry Fluorescence Glioblastoma Human Image Cytometry Ion Channel Gating metabolism pathology pharmacology Platelet-Derived Growth Factor Polyamines Signal Transduction Support, Non-U.S.Gov't Support, U.S.Gov't,P.H.S. Tumor Cells, Cultured
Megjelenés:	Cancer Research. - 52 : 24 (1992), p. 6782-6789. -
További szerzők:	Szöllősi János (1953-) (biofizikus) Basu, Hirak S. Marton, Laurence J.
Internet cím:	elektronikus változat
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