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Biomedical subjects

D Breviario

Publications and source records attributed to D Breviario.

24 records · Page 2Linked to original sources
PubMed1984

Replication pattern of human repeated DNA sequences.

Either aphidicolin- or thymidine-synchronized human HL-60 cells were used to study the replication pattern of a family of human repetitive DNA sequences, the Eco RI 340 bp family (alpha RI-DNA), and of the ladders of fragments generated in total human DNA after digestion with XbaI and HaeIII (alpha satellite sequences). DNAs replicated in early, middle-early, middle-late and late S periods were labelled with BUdR or with [3H]thymidine. The efficiency of the cell synchronization procedure was confirmed by the transition from a high-GC to a high-AT average base composition of the DNA synthesized going from early to late S periods. By hybridizing EcoRI 340 bp repetitive fragments to BUdR-DNAs it was found that this family of sequences is replicated throughout the entire S period. Comparing fluorograph densitometric scans of [3H]DNAs to the scans of ethidium bromide patterns of total HL-60 DNA digested with XbaI and HaeIII, it was observed that DNA synthesized in different S periods is characterized by approximately the same ladder of fragments, while the intensity of each band may vary through the S phase; in particular, the XbaI 2.4 kb fragment becomes undetectable in late S.

Base Sequence↗
PubMed1984

Phorbol ester-induced changes in human leukemic pre-B lines.

The genomic analysis of four non-T-leukemic lines NALM-1, KM-3, NALL-1, and NALM-16 shows a rearranged configuration of the immunoglobulin mu chain genes, indicating that they represent early B stages of differentiation. The differentiative potential of these pre-B cell lines was tested using the phorbol ester tumor promoter 12-O-tetradecanoyl phorbol-13-acetate (TPA). Phenotypic changes in the immunological marker profile (induction of BA-1 and BA-2 antigens) are observed, presumably reflecting events occurring in precursor B cells. However, no maturation to immunoglobulin mu chain production could be obtained. The limited maturation can be explained on the basis of possible aberrant mu chain gene rearrangements, or other mechanisms of a regulatory nature, preventing the transcription and/or the translation of rearranged mu chain genes.

Antigens, Neoplasm↗
PubMed1983

Acquisition of deoxyguanosine resistance by TPA-induced T lymphoid lines.

The human leukemic T cell line 8402, which contains terminal deoxynucleotidyl transferase (TdT) and phenotypically resembles precursor thymocytes, when exposed to the phorbol ester 12-O-tetradecanoyl phorbol-13-acetate (TPA) undergoes in vitro T maturation. TdT disappears from virtually all the cells and a fraction of TdT- -cells express specific T surface markers, such as the T3 determinant. Like T lymphocytes from the thymus, 8402 cells are extremely sensitive to the cytotoxic effect of deoxyguanosine (dGuo). As a consequence of TPA treatment, resistance to dGuo is observed in 8402, as well as in two other TdT+ lymphoid T cell lines, Molt-4 and CEM-10. These results suggest the occurrence of changes in deoxynucleoside metabolism in TPA-treated cells related to the in vitro maturation process. Maturation of 8402 cells, once started, progresses in the presence of additional physiologic stimuli provided by conditioned medium from lymphocyte culture, because a portion of cells display the T8+/T4- phenotype characteristic of cytotoxic/suppressor T cells. This in vitro lymphoid system may thus be used to study the relationships of molecular differentiation between precursor thymocytes and cytotoxic/suppressor T cells.

Animals↗