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Biomedical subjects

J K Yee

Publications and source records attributed to J K Yee.

42 records · Page 3Linked to original sources
PubMed1985

Retroviral vector-mediated gene transfer into human hematopoietic progenitor cells.

The transfer of the human gene for hypoxanthine phosphoribosyltransferase (HPRT) into human bone marrow cells was accomplished by use of a retroviral vector. The cells were infected in vitro with a replication-incompetent murine retroviral vector that carried and expressed a mutant HPRT complementary DNA. The infected cells were superinfected with a helper virus and maintained in long-term culture. The production of progeny HPRT virus by the bone marrow cells was demonstrated with a colony formation assay on cultured HPRT-deficient, ouabain-resistant murine fibroblasts. Hematopoietic progenitor cells able to form colonies of granulocytes or macrophages (or both) in semisolid medium in the presence of colony stimulating factor were present in the nonadherent cell population. Colony forming units cloned in agar and subsequently cultured in liquid medium produced progeny HPRT virus, indicating infection of this class of hematopoietic progenitor cell.

Animals↗
PubMed1985

Locations of bacteriophage T4 origins of replication.

Partially replicated bacteriophage T4 DNA containing cytosine was isolated from cells 6.5 and 7 min after infection and cleaved with restriction endonuclease BglII or BamHI. Positions of replication eyes relative to the cleavage sites were observed by electron microscopy. Four groups of eyes were found. They are consistent with replication from origins located at map positions 34, 60, 73, and 86 kilobases. In individual molecules that contained two or three eyes, the distribution of the eyes agreed with the initiation of replication at more than one of these four assigned origins and possibly at two additional origins located near 15 and 110 kilobases, which were reported by P. M. Macdonald, R. M. Seaby, W. Brown, and G. Mosig (p. 111-116, in D. Schlessinger, ed., Microbiology--1983, 1983) and M. E. Halpern, T. Mattson, and A. W. Kozinski (Proc. Natl. Acad. Sci. U.S.A. 76:6137-6141, 1979).

Chromosome Mapping↗
PubMed1981

Alignment of a restriction map with the genetic map of bacteriophage T4.

A restriction map of the bacteriophage T4 genome was aligned with the T4 genetic map. Included were the cleavage sites for BamHI, BglII, KpnI, PvuI, SalI, and XbaI. The alignment utilized the fact that the T4 genetic map had been oriented previously with respect to a T2/T4 heteroduplex map. DNA fragments from a BglII digestion of cytosine-containing DNA from a T4 dCTPase- denA denB(rIIH23B) alc mutant were hybridized with full-length chromosomal strands of bacteriophage T2, and the heteroduplexes were examined by electron microscopy. From their lengths and patterns of substitution and deletion loops, the heteroduplexes formed with 6 of the 13 BglII fragments could be unambiguously identified and positioned on the T2/T4 heteroduplex map. The ends of the T4 DNA strands in the heteroduplexes directly identified the location of 10 BglII cleavage sites. The remaining three BglII cleavage sites could be assigned to the T2/T4 heteroduplex map based on their relative locations on the restriction map. It was also possible to identify the source of the DNA strands (i.e., T2 or T4) in four previously unassigned deletion loops on the T2/T4 heteroduplex. Among the BglII fragments identified in heteroduplexes was the fragment containing the rIIH23B deletion; this deletion was used as the primary point of reference for alignment of the T4 restriction map with the T2/T4 heteroduplex map and, hence, with the T4 genetic map.

Chromosome Mapping↗
PubMedDate not supplied

Wild-type p53 suppresses the malignant phenotype in breast cancer cells containing mutant p53 alleles.

We have examined the effect of expression of a retrovirally mediated wild-type (wt) p53 allele on the neoplastic properties of five human breast cancer cell lines expressing mutant p53. After infection with the retroviral vector Lhp53RNL expressing both the neomycin phosphotransferase gene and the wt p53 gene, the ability of infected cells to form colonies in G418 selective medium was markedly reduced and their morphology demonstrated changes toward a flattened and enlarged phenotype. Employing a high multiplicity of infection (MOI) with Lhp53RNL without neoR selection, the replication of wt p53-reconstituted cells was greatly reduced. The ability of the genetically modified cells to produce colonies in semi-solid medium and to form tumors in recipient nude mice was also markedly suppressed. Restoration of wt p53 expression in human breast cancer cells expressing endogenous mt (mutant) p53 can suppress some aspects of the malignant phenotype by a trans-dominant mechanism.

Alleles↗