Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Primary and secondary cell-mediated cytotoxic responses to FBL-3 cells, a syngeneic Friend virus-induced leukemia in C57BL/6 mice, could be generated by in vitro techniques as tested by the 125IUdR release assay. The specificity of the cytotoxic reactions appeared to be directed against the Friend type-specific antigen and the FMR (Friend, Moloney, Rauscher) antigen which were also the major antigens for transplantation immunity to FBL-3. In comparison to the primary cytotoxic response, the secondary cytotoxic response was accelerated (detected at an earlier time after sensitization), enhanced (gave much higher levels of cytotoxicity), was also longer lasting, and could be induced by a wide dose range of tumor cells. The secondary response could only be induced with lymphocytes obtained from regressors that were resistant to FBL-3 challenge; lymphocytes from mice with progressive tumor growth had no detectable secondary response. It was found that both induction phase and the effector phase of cytotoxic responses were T cell dependent. The characteristics of these reactions were thus very similar to those obtained with in vivo immunization or challenge, providing a good correlation with in vivo tumor immunity.
 ...
PMID:Cell-mediated immunity to friend virus-induced leukemia. IV. In vitro generation of primary and secondary cell-mediated cytotoxic responses. 5 34

The inoculation of L2C guinea pig leukemia cells into strain 2 guinea pigs results in the death of the animals within 12 to 15 days. Death is preceded by the simultaneous appearance in the plasma of (i) elevated leukocyte levels, (ii) extracellular virus particles, and (iii) a particle-associated RNA-directed DNA polymerase. This enzyme activity has a cation preference identical to that of the type B bromodeoxyuridine-induced guinea pig virus, i.e., an Mg2+ optimum at 20 mM and no activity using Mn2+. Competitive molecular hybridization studies also revealed that the plasma of leukemic guinea pigs contained approximately 2 X 10(9) genome equivalents per ml of an RNA that is homologous to the RNA of the bromodeoxyuridine-induced guinea pig virus. Morphological observations indicate that most, but not all, of the extracellular particles observed in leukemia plasma are derived from the intracisternal particles seen in the L2C tumor cells. The possibilities that either two viral populations are present or that the in vivo morphogenesis of the type B bromodexoyuridine-inducible guinea pig virus is markedly different from its in vitro morphogenesis are discussed.
 ...
PMID:Characterization of the oncornavirus particles in the plasma of guinea pigs with L2C leukemia. 5 78

An antiserum was produced by immunization of rabbits with the membrane fraction of a lymphoblastoid cell line, RPMI 4265. This antiserum reacted against leukemia-associated antigens on immature blast cells of 24 patients with acute leukemia (13 myeloblastic, 11 lymphoblastic). No reactivity was observed against morphologically normal blood mononuclear cells from patients in remission, cells from normal control subjects and patients with unrelated disorders, phytohemagglutinin-induced lymphoblasts, or normal bone marrow cells. Reactivity against leukemia cells was not reduced by absorption with fetal tissues. These findings were consistent with the presence of tumor-associated antigens on leukemia cells. The antigens were detectable neither during hematologic remission nor on cells from patients with unrelated diseases.
 ...
PMID:Leukemia-associated antigens detected by heterologous antisera. 6 42

Ethidium bromide (2,3-diamino-5-ethyl-6-phenylphenanthridinium bromide) significantly inhibited the RNA-dependent DNA polymerase of types A and C particles isolated from transplanted adenovirus 12-induced tumors of CBA mice. It was also cytotoxic for an established in vitro line of adenovirus 12-induced tumor cells of CBA mice and caused cell death, inhibition of [3H]thymidine uptake, and a significant reduction of cells in metaphase. Ethidium bromide significantly inhibited the in vivo growth of transplanted adenovirus 12-induced tumor cells of CBA mice, simian virus 40-induced tumor cells of hamsters, and murine leukemia virus-induced lymphoma cells of BALB/c mice. The compound may have exerted the antitumor activity by selectively affecting oncornavirus in the tumor cells.
 ...
PMID:Effect of ethidium bromide on transplanted virus-induced tumor cells. 6 62

Rauscher leukemia virus RNA-directed DNA polymerase has been purified to near homogeneity (greater than 90% pure) using affinity chromatography on polycytidylate-agarose with over 85% recovery of input enzymatic activity. The purified enzyme has a molecular weight of approximately 70,000 and appears to consist of a single polypeptide chain. The enzyme is free of DNase, but has RNase H activity. Analysis of the requirements for optimal rates of DNA synthesis by this enzyme using synthetic and natural template-primers has revealed template-specific variations in such requirements. During these studies it was observed that DNA synthesis catalyzed by Rauscher leukemia virus DNA polymerase is inhibited by the addition of inorganic phosphate. An analysis of the mechanism of phosphate inhibition was carried out using the synthetic template-primer poly(A)-(dT)10. It appears that by some mechanism, possibly involving the substrate binding site of the enzyme, phosphate ions inhibit DNA synthesis with a more acute effect on the rate of chain growth than on that of initiation. The extension of these studies to DNA synthesis catalyzed by a variety of mammalian type C viral reverse transcriptases revealed that low levels ( less than or equal to 2 mM) of inorganic phosphate strongly inhibited DNA synthesis. The susceptibility to phosphate inhibition appears unique to mammalian type C viral enzymes since the type B viral enzyme, Escherichia coli DNA polymerase I, avian myeloblastosis virus and Mason Pfizer monkey tumor virus reverse transcriptase and cellular DNA polymerases alpha and gamma are not inhibited by inorganic phosphate. This phenomenon of phosphate inhibition of various DNA polymerases, therefore, provides a new basis for the differentiation of the sources and nature of these enzymes.
 ...
PMID:Purification and properties of Rauscher leukemia virus DNA polymerase and selective inhibition of mammalian viral reverse transcriptase by inorganic phosphate. 6 68

It was previously demonstrated that the 60,000 dalton (p60) precursor-like polyprotein containing murine p30 was a constituent of the feline leukemia virus pseudotype of Moloney sarcoma virus [m1MSV(FeLV)]. It is now shown that p60 is detected in cells of five mammalian species transformed by m1MSV, indicating that p60 is specified by this genome. Moreover, little or no murine p30 is detected in the m1MSV-transformed cells, suggesting that the murine group p30 antigenic reactivity of S + L- cells is ude to p60. Pulse-chase studies in cells producing m1MSV(FeLV) show that p60 is the largest polypeptide detectable during the pulse, and that intracellular p60 is not cleaved into smaller (for example, p30) polypeptides during chase periods of up to 10 hr. The lack of cleavage of p60 is in contrast to the properties of p30 precursors detected in cells containing replicating avian or mammalian RNA tumor viruses. The inefficient cleavage of intracellular p60 and the kinetics of appearance of murine p30 in extracellular m1MSV(FeLV) suggest that p60 cleavage to p30 occurs in cells shortly before virus release. While only p60 was detected in the m1MSV-transformed cells, p60 and p70 were detected in m3MSV-transformed cells, and no immunoprecipitable polypeptides were detected in HT-1 MSV-transformed cells. The observed differences in the intracellular polypeptide expression by each of the strains of MSV suggests differences in genetic content.
 ...
PMID:Cells transformed by certain strains of Moloney sarcoma virus contain murine p60. 6 30

Suppressor cells from syngeneic P815 mastocytoma-bearing DBA/2 mice that inhibit in vitro generation of specific anti-tumor cytotoxicity were characterized. Suppressive activity was almost completely eliminated by treating suppressive spleen cells with anti-theta serum and complement. Treatment with anti-mouse lg serum and complement or with carbonyl iron did not affect their suppressive activity. When suppressive thymocytes from P815 tumor-bearing DBA/2 mice were tested for their capacity to inhibit the generation of cytotoxicity against L1210 cells, a leukemia line in DBa/2 mice, they did not affect the activity, indicating that the supressor cells in the thymocytes of P815 tumor-bearing mice are specific to the tumor. When Ficoll-Hypaque density cell separation was carried out with cytotoxic spleen cells and suppressive spleen cells from 815 tumor-bearing mice, the dense fraction was enriched for kiler cells whereas the suppressive activitty was mainly recovered in the light fraction. Therefore, killer cells and suppressor cells in P815 tumor-bearing mice are thought to be distinct populations.
 ...
PMID:Characterization of suppressor cells in mice bearing syngeneic mastocytoma. 6 23

Both adult (I) and embryonic (II) forms of uridine kinase have been identified in the transplantable EL-4 leukemia of C57BL/6 mice and in the P815Y mastocytoma of DBA/2 mice. Only Species I is found in primary tumor cells of lymphoid orgin (virus-induced feline lymphosarcoma, human acute and chronic lymphocytic leukemia) and in normal calf thymocytes and porcine peripheral blood lymphocytes; Species I was induced 4-fold upon stimulation of the normal blood lymphocytes with phytohemagglutinin. The level of uridine kinase activity in the feline lymphosarcoma of thymus-dependent lymphocyte orgin and childhood lymphocytic leukemia of possible thymus-dependent lymphocyte or null-cell origin was similar to the induced level in phytohemagglutinin-stimulated normal lymphocytes, i.e., thymus-dependent lymphocytes. In contrast lymphocytes of a patient with chronic lymphocytic leukemia of thymus-independent lymphocyte origin had a level of uridine kinase activity comparable to that of the unstimulated normal lymphocytes or thymocytes. The uridine kinase activity in the EL-4 tumor cells was repressed by acute treatment of the mice with 5-azacytidine.
 ...
PMID:Uridine kinase activities in normal and neoplastic lymphoid cells. 6 93

The genetics of late appearing MSV tumors showing a progressive growth pattern in AKR mice was investigated. The late MSV tumor response in F1 hybrids depended on the genetic background of the non-AKR parent. Within the 4-month observation period following virus injection, (CBA X AKR) F1, (DBA/2 X AKR)F1, and (NIH X AKR)F1 developed progressing MSV tumors, which exhibited latency and growth behavior comparable to that seen in AKR mice, (BALB X AKR)F1, (B6 X AKR)F1, and (B10br x akr)f1 mice did not show any late MSV tumors. In contrast to early regressing M-MSV tumors, whose development is independent of Fv-1 genotype, late MSV tumor progression is largely a function of this gene, since all late tumors which appeared in (B10BR x AKR) x AKR were observed in Fv-1n homozygous mice, H-2k halotype is a further factor in the occurrence of late MSV tumors, at least in (B6 x AKR) x AKR mice. In crosses of AKR with Fv-1 compatible mice, tumor appearance was strongly associated with inheritance of AKR-Mulv, and MSV recovered from late tumors of first back-cross animals appeared to be a new pseudotype with the endogenous AKR-MuLV. It is suggested that the host genetic control in both early and late MSV tumors is exerted mainly on the helper component of the leukemia-sarcoma complex.
 ...
PMID:Genetics of murine sarcoma virus (MSV)--induced tumors in AKR mice: Evidence that late progressing and early regressing tumors are controlled by different gents. 6 12

Acute myelogenous leukemia (AML) of the inbred Wistar/Furth (W/Fu) rat is pathophysiologically similar to human AML. Subcutaneous transplantation of 1.0 X 10(6) cells of a clonal tissue culture line of W/Fu AML into 6- to 8-week-old rats produced local myeloblastomas in 8--10 days which progressed to infiltration of regional nodes, replacement of greater than 90% of the bone marrow, ascites, and fatal peripheral blood leukemia with concomitant hyperlysozymemia. Single doses of adriamycin, daunomycin, actinomycin, cytosine arabinoside, or Cytoxan in rats with 1.0 cm myeloblastomas produced complete tumor regression while bu-sulfan, vinblastine, vincristine, dexamethasone, and Methotrexate was relatively ineffective. Responses were associated with delay in progression to peripheral blood leukemia and prolonged survival. Similar results were obtained following treatment of rats with already disseminated leukemia. The demonstration of response to drugs known active against human AML indicates that the W/Fu AML should be a valuable model for rapid evaluation of new chemotherapeutic agents for clinical use.
 ...
PMID:Chemotherapeutic remissions in Wistar Furth rat acute myelogenous leukemia: a model for human AML. 6 30


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>