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P S Sarin

Publications and source records attributed to P S Sarin.

11 recordsLinked to original sources
PubMed1979

Characterization of an RNA-directed DNA-polymerase from a cell line derived from a radiation-induced lymphoma in mice.

An RNA-directed DNA polymerase was purified from a cell line derived from a radiation-induced lymphoma in NIH Swiss mice which produced non-infectious type C virus particles. The enzyme was isolated from a high speed particulate fraction which bands at a density of 1.16--1.19 g/ml in a sucrose gradient, and purified by successive chromatography on DEAE-cellulose, phosphocellulose and hydroxyapatite. The purified DNA polymerase has a molecular weight of 68 000, a pH optimum of 7.5, a KCl optimum of 50 mM, and a Mn2+ optimum of 0.25 mM. It prefers (dT)15 . (A)n to (dT)15 . (dA)n as the primer template and transcribes the poly(C) strand of (dG)15 .(C)n and (dG)15 . (OMeC)n. It transcribes heteropolymeric regions of avian myeloblastosis virus 70 S RNA, and is inhibited by antiserum to Rauscher murine leukemia virus DNA polymerase. Comparison of the properties of DNA polymerase purified from radiation-induced lymphoma cells with the DNA polymerase purified from non-defective murine type C RNA tumor viruses shows that the mouse lymphoma enzyme is both biochemically and immunologically related to murine leukemia virus DNA polymerases.

Animals↗
PubMed1979

Loss of terminal deoxynucleotidyl transferase (TdT) activity as a predictor of emergence of resistance to chemotherapy in a case of chronic myelogenous leukemia in blast crisis.

A 46-year-old female with chronic myelogenous leukemia (CML) in blast crisis was monitored for terminal deoxynucleotidyltransferase (TdT) activity of marrow and peripheral blood throughout the course of her illness. TdT was elevated at the time of diagnosis of blastic transformation, and the patient easily obtained remission after therapy with hydroxyurea, 6-mercaptopurine and prednisone. The patient enjoyed a remission of eight months duration, and at time of relapse, marrow TdT was again elevated. The patient again obtained complete remission with the same regimen, with the addition of vincristine, given weekly. This second remission was shortlived, however, and at relapse marrow TdT activity was undetectable. Subsequently, the patient failed to achieve remission, despite the use of a wide variety of chemotherapeutic agents. This case suggests that loss of TdT activity in blastic CML cells marks the emergence of cells resistant to existing chemotherapeutic agents.

Antineoplastic Agents↗
PubMed1979

Chromatin conformation during cell differentiation of human myeloid leukemia cells.

A novel human promyelocytic leukemia cell line (HL-60) has been shown to form terminally differentiated granulocytes in the presence of dimethyl-sulfoxide (DMSO), some other chemicals, or colony stimulating factor. Compared to chromatin from HL-60 cells, chromatin from DMSO treated HL-60 cells showed an enrichment in low temperature melting material. The decrease in thermostability of chromatin from HL-60 cells after DMSO treatment is similar to the shift in thermostability of chromatin from human lymphocytes after stimulation with phytohemagglutinin (PHA). These results suggest that changes in the thermostability of chromatin may not be specific for cell differentiation or PHA stimulation.

Adult↗
PubMed1977

Purification and characterization of baboon endogenous virus DNA polymerase.

An RNA-directed DNA polymerase was purified from baboon endogenous type-C virus by successive column chromatography on DEAE cellulose, phosphocellulose and hydroxyapatite. The purified DNA polymerase has a molecular weight of 68 000, a pH optimum of 8.0, a Mn2+ optimum of 1 mM, and a KCl optimum of 40 mM. The purified enzyme transcribes heteropolymeric regions of viral 60--70 S RNA isolated from different type-C viruses. The purified enzyme is immunologically related to a similarly purified polymerase from the cat endogenous type-C virus RD114.

Animals↗
PubMed1976

Purification and characterization of gibbon ape leukemia virus DNA polymerase.

An RNA directed DNA polymerase was purified over 2500 fold from gibbon ape leukemia virus by successive column chromatography on Sephadex G100, DEAE cellulose, phosphocellulose and hydroxyapatite. The purified DNA polymerase has a molecular weight of 68 000, a pH optimum of 7.5, a Mn2+ optimum of 0.8 mM, and KCl optimum of 80 mM. The purified enzyme transcribes heteropolymeric regions of viral 60-70 S RNA isolated from avian myeloblastosis virus, Rauscher murine leukemia virus and simian sarcoma virus and it is inhibited by antiserum prepared against either gibbon ape leukemia virus or simian sarcoma virus DNA polymerases.

Animals↗
PubMed1976

Terminal transferase in human bone-marrow lymphocytes.

Activity of the enzyme terminal transferase (TdT) has been localised in normal human bone-marrow lymphocytes. These cells may represent a prothymocyte population, which, on malignant transformation, may give rise to acute lymphoblastic leukaemia, and to some cases of chronic granulocytic leukaemia in the blastic phase.

Bone Marrow↗
PubMed1976

Terminal deoxynucleotidyl transferase as a biological marker for human leukemia.

High levels of terminal deoxynucleotidyl transferase have been observed in leukocytes of 7 out of 20 patients with chronic myelogenous leukemia in acute blast phase of the disease. These levels are comparable to the levels observed in human and calf thymus gland and cell lines with some T cell characteristics (Molt 4 and 8402). Negligible levels of this activity were observed in chronic myelogenous leukemia not in an acute blast phase of the disease, chronic lymphocytic leukemia, human B cells, mature T cells, and the mixed population of lymphocytes present in normal human blood. The detection of this enzyme in some patients with chronic myelogenous leukemia in acute blast phase of the disease suggests that the blast proliferation may involve primitive stem cells which have more lymphoid than myelogenous characteristics. This enzyme assay may be of use as a biological marker for following patients during treatment and in remission.

Cations, Divalent↗
PubMed1976

Terminal deoxynucleotidyl transferase activities in human blood leukocytes and lymphoblast cell lines: high levels in lymphoblast cell lines and in blast cells of some patients with chronic myelogenous leukemia in acute phase.

Terminal deoxynucleotidyl transferase, an enzyme which catalyzes the polymerization of deoxyribonucleoside triphosphates, elongating oligo- or polydeoxynucleotide chains, but without direction from a nucleic acid template, is thought to be specific for thymus gland and thymus-derived cells. We have confirmed the observations that high levels are characteristic of thymus gland with both human and calf tissue and that elevated levels may be found in some cases of acute lymphocytic leukemia. High levels were also found in human lymphoblast cell lines with T-cell characteristics, and insignificant activity was observed in leukocytes of patients with chronic myelogenous leukemia not in acute blast phase of the disease, chronic lymphocytic leukemia, human B-cells, and normal human blood lymphocytes even after stimulation with phytohemagglutinin. However, high levels (approximately 200 nmoles/hr/10(9) cells) equivalent to those in thymus tissue and lymphoblast cell lines with T-cell characteristics were found in the peripheral blood blast cells of four patients with chronic myelogenous leukemia in an acute blast phase of their disease. One hypothesis that may explain the present results is that in chronic myelogenous leukemia in acute blast phase of the disease the proliferative blast response may not always be myeloblasts but in some cases it may be lymphoblasts.

Adult↗
PubMed1975

Biochemical approaches to detection of viral related information in human acute leukemic cells.

Two biochemical markers that have been utilized for the detection of viral related information in human acute leukemic cells are: 1) The reverse transcriptase and 2) a high molecular weight RNA with viral related nucleotide sequences. This paper summarizes evidence that shows that the reverse transcriptase isolated from human acute leukemic cells is biochemically related to the reverse transcriptase from RNA tumor viruses.

Acute Disease↗