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Biomedical subjects

V G Dev

Publications and source records attributed to V G Dev.

At least 37 records · Page 2Linked to original sources
PubMed1983

Unusual translocations t(2;6) and t(?;22) in a child with acute myelocytic leukemia.

A 13-month-old female with middle and upper lobe pneumonia showed a high WBC count with 99% blasts. From hematologic studies the condition was diagnosed as acute myelocytic leukemia (AML). In spite of aggressive chemotherapy, the patient died. Unstimulated peripheral blood culture and bone marrow cells revealed a translocation between a chromosome #2 and #6. An interstitial segment of 2q had been translocated to 6p. A chromosome #22 was also abnormal, having acquired a dark band around the long arm.

Chromosome Aberrations↗
PubMed1983

Fragile X expression is decreased by 5-azacytidine and S-adenosylhomocysteine.

A lymphoblastoid cell line derived from a patient with fragile X chromosome exhibited fragility only when 5-fluoro-2'-deoxyuridine (FUdR) was added to the culture medium. Addition of methionine with FUdR greatly increased the frequency of fragile X. Addition of 5-azacytidine (an inhibitor of methylation at the level of DNA) or S-adenosylhomocysteine (an inhibitor of the synthesis of the methyl group donor S-adenosylmethionine) reversed the effect of methionine as well as that of FUdR. It is proposed that DNA methylation is in some way involved in the mechanism of fragile X expression.

Azacitidine↗
PubMed1982

Antiarsonate antibody response: a model for studying antibody diversity.

The use of two polyclonal activators, dextran sulfate (DxS) and lipopolysaccharide (LPS), with or without the presence of additional antigen, is presented here as a system for exploring the antibody response of normal (naive) amd primed B cells. This system expands populations of cells not normally observed under in vivo regulation. By fusing such unnaturally activated B cells, anti-p-azophenylarsonate hybrids were produced that secrete different isotypes of antibodies. The frequencies of isotopes expressed by these hybrids may correspond to the chromosomal order of the heavy chain genes because greater numbers of IgM- and IgG3-secreting hybrids were produced than IgG2a hybrids. Only one IgA hybrid was observed. When DxS and LPS were used to stimulate antigen-primed B cells, hybrids were generated that simultaneously secrete two isotopes of antibody. These hybrids may represent a model of the antigen-stimulated maturational class-switch step observed in normal B cells that involves the expression of IgM and IgG isotypes by the same cell. Such hybrids offer an opportunity to study antibody regulation and diversity by examining the rearrangement of genes during the Ig switch, by exploring the nature of the necessary transitions of mRNA transcription and translation to produce functional antibodies, and by probing the structure and specificity of such antibodies.

Animals↗
PubMed1981

Characterization of a novel human pre-B leukemia cell line.

The derivation of a new human pre-B cell line from the leukocytes of a girl in the leukemic phase of lymphoblastic lymphoma is reported. Cells of this line, termed SMS-SB, synthesized mu but not light chains. These mu-chains were found only in the cytoplasm and were not secreted. SMS-SB cells bore HLA-DR determinants. They did not express the common ALL antigen or terminal deoxynucleotidyl transferase and, therefore, differed from previously described human pre-B leukemia cell lines. SMS-SB cells resembled certain Abelson leukemia virus-transformed mouse bone marrow cells. Except for the lack of formed mouse bone marrow cells. Except for the lack of mu secretion, the phenotype of SMS-SB cells was the same as the major subpopulation of marrow pre-B cells.

Adolescent↗
PubMed1980

Duplication 12q mosaicism in two unrelated patients with a similar syndrome.

Two unrelated children with a similar syndrome were found to have mosaicism for a cell line containing one chromosome 12 with an additional faintly G-banding staining region that apparently represents a duplication of the distal portion of the long arm. The homology and the other chromosomes are normal, as are the parental chromosomes. The remarkable phenotypic similarity of the 2 patients and their resemblance to 2 previously reported patients with duplication of the same chromosome region suggests that duplication 12q24 results in a clinically identifiable malformation syndrome.

Abnormalities, Multiple↗
PubMed1979

Partial translocation of NOR and its activity in a balanced carrier and in her cri-du-chat fetus.

Cytogenetic analysis of a balanced reciprocal translocation t(5;13) carrier and her unbalanced 5p- conceptus was carried out. This carrier mother had previously given birth to a child with cri-du-chat syndrome. Silver staining demonstrated the breakpoint on 13p within the nucleolus organizer region (NOR). In the carrier, the NORs both at the original site (13p) and at the translocated site (5p) were silver-stained, indicating that the rRNA genes at both sites were transcribed. The NOR at the derivative chromosome 5 was also silver-stained in the fetus.

Adult↗
PubMed1979

Reactivation of silent rRNA genes by simian virus 40 in human-mouse hybrid cells.

Mouse-human hybrid cells were used to study the ability of simian virus 40 to regulate the expression of rRNA genes in vivo. In these hybrid cells, only the rRNA genes of the dominant species are expressed; the genes for the rRNA of the recessive species are silent. Simian virus 40 infection of these hybrids led to the production of two distinct 28S rRNA species as analyzed by agarose/2.4% polyacrylamide gel electrophoresis. These species were identified as human and mouse rRNAs. This result was confirmed by histochemical studies which indicated that the nucleolus organizer regions of both mouse and human chromosomes were actively synthesizing rRNA in the virus-infected hybrid cells. These results indicate that simian virus 40 infection can induce the expression of otherwise silent rRNA genes.

Animals↗
PubMed1978

Nucleolus organizer activity and the origin of Robertsonian translocations.

Chromosomes with active nucleolus organizer regions (NOR's) were identified by combined Q-banding (in some cases), and silver staining in mouse cell lines. NOR-bearing chromosomes were overrepresented among the chromosomes involved in Robertsonian translocations in LM(TK-), A9, and RAG cell lines. Usually only one NOR-bearing chromosome was seen in any biarmed chromosome; relatively few contained two NOR-bearing chromosomes. Thus the nucleolus plays an important role, but nucleolar fusion is relatively unimportant, in the origin of Robertsonian translocations in the mouse.

Animals↗
PubMed1978

Human tumor and rodent-human hybrid cells with an increased number of active human NORs.

A human fibrosarcoma line, HT1080-6TG, with a near diploid number of chromosomes, has an average of 7.3 chromosomes with an Ag-stained nucleolus organizer region (NOR). Cells of this line with an increased number of chromosomes have an increased number of Ag-stained NORs. This cell line has been used as the human parent in constructing mouse-human and rat-human hybrids that segregate rodent chromosomes. The hybrid ccell lines, which have 100 or more chromosomes per cell, show a proportionate increase in the number of Ag-stained NORs (means, 11.4--16.8). The frequency of association of acrocentric chromosomes increases in a similar fashion. There is no evidence of inactivation of human NORs in these cells.

Animals↗