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Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of neonatal and perinatal thymectomy on mammary tumorigenesis in (C57BL X I)F1fC3H hybrid female mice were determined. When hybrid females were neonatally thymectomized by controlled suction, a procedure that removes thymic lobes completely, a large proportion of animals developed stigmas of a fulminant wasting disease and died before tumors developed. However, when hybrid females were subjected to neonatal thymectomy by continuous suction, a procedure that resulted in retention of thymic remnants, they survived and manifested a significant prolongation of latent period before tumorigenesis. When complete removal of the thymus was carried out in the perinatal period, the effect on mammary tumorigenesis was critically dependent on the age at surgery. The procedure was without effect when performed at 1, 3, and 8 weeks of age. However, when it was performed at 9-12 days of age, there was a delay or a decrease in the appearance of mammary tumors. The extent of T-cell depletion and/or its timing in relationship to the introduction of murine mammary tumor virus appeared to play a critical role in determining the effect on eventual tumor development.
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PMID:Inhibition of mammary tumors by incomplete T-cell depletion. 19 Apr 16

A continuous lymphoblastoid cell line was established from a JMV tumor transplant related to Marek's disease (MD). It is designated RPL1 (JMV) lymphoblastoid cell line. This cell line contains DNA sequences complementary to MD virus DNA and has an antigen similar to MD-tumor-associated surface antigen (MATSA). However, it lacks any MD virus (MDV) rescuable in vivo or in vitro. The cell line has surface antigens typical of chicken thymus cells (T cells) and histocompatability antigens different from those of the host chicken.
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PMID:A nonproducer T lymphoblastoid cell line from Marek's disease transplantable tumor (JMV). 19 Sep 95

High histaminase [amine:oxygen oxidoreductase (deaminating) (pyridoxal-containing), EC 1.4.3.6] activity is found in certain human tumors and in the placenta of most mammals. The present study explores the relationship of tumor histaminase to histaminases found in placenta and other human, pig, and rat tissues. The electrophoretic mobility and Michaelis constants for the deamination of histimine and putrescine were identical for histaminases from human placenta and from medullary thyroid carcinoma. An antibody was raised in rabbits against human placental histaminase that was highly purified by a new affinity procedure. In separate studies, using inhibitory concentrations of antibody and a second antibody precipitation technique, identical patterns of immunoreactivity were found for histaminases from human placenta, kidney, medullary thyroid carcinoma, and small cell lung carcinoma; human intestinal histaminase crossreacted well but less strongly than did enzymes from these other tissues. Histaminases from pig kidney, pig intestine, and rat intestine showed no crossreaction; histaminases from rat thymus and adrenal gland showed minimal crossreactivity. The findings suggest that placental histaminase activity is not a unique product of a fetal or trophoblastic genome. The presence of histaminase in malignancies does not appear to be an example of ectopic tumor production of a placental trophoblastic protein.
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PMID:Histaminase (diamine oxidase) activity in human tumors: an expression of a mature genome. 19 38

The synthesis and processing of feline leukemia virus (FeLV) polypeptides were studied in a chronically infected feline thymus tumor cell line, F-422, which produces the Rickard strain of FeLV. Immune precipitation with antiserum to FeLV p30 and subsequent sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) were used to isolate intracellular FeLV p30 and possible precursor polypeptides. SDS-PAGE of immune precipitates from cells pulse-labeled for 2.5 min with [35S]methionin revealed the presence of a 60,000-dalton precursor polypeptide (Pp60) as well as a 30,000-dalton polypeptide. When cells were grown in the presence of the proline analogue L-azetidine-2-carboxylic acid, a 70,000-dalton precursor polypeptide (Pp70) was found in addition to Pp60 after a 2.5-min pulse. The cleavage of Pp60 could be partially inhibited by the general protease inhibitor phenyl methyl sulfonyl fluoride (PMSF). This partial inhibition was found to occur only if PMSF was present during pulse-labeling. Intracellular Pp70 and Pp60 and FeLV virion p70, p30, p15, p11, and p10 were subjected to tryptic peptide analysis. The results of this tryptic peptide analysis demonstrated that intracellular Pp70 and virion p70 were identical and that both contained the tryptic peptides of FeLV p30, p15, p11, and p10. Pp60 contained the tryptic peptides of FeLV P30, P15, and P10, but lacked the tryptic peptides of P11. The results of pactamycin gene ordering experiments indicated that the small structural proteins of FeLV are ordered p11-p15-p10-p30. The data indicate that the small structural proteins of FeLV are synthesized as part of a 70,000-dalton precursor. A cleavage scheme for the generation of FeLV p70, p30, p15, p11, and p10 from precursor polypeptides is proposed.
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PMID:Analysis of intracellular feline leukemia virus proteins II. Generation of feline leukemia virus structural proteins from precursor polypeptides. 19 17

Antisera prepared in syngeneic mice by hyperimmunization with intact SV40-transformed mouse cells or with somatic cell hybrids between SV40-transformed human and normal mouse cells exhibit anti-SV40 tumor (T) antigen reactivity. Athymic mice bearing tumors formed by SV40-transformed mouse, human or mouse-human hybrids were not reactive with SV40 T antigen. Anti-thymocyte serum (ATS)-treated mice also lacked T antigen reactivity during suppressive treatment but developed antibody to T antigen after discontinuing ATS treatment and tumor regression. We conclude that that presence of growing tumors in the mouse is not necessary for the production of anti-SV40 T antigen antibodies but that helper thymus-derived cells are essential for the humoral response.
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PMID:Reactivity to SV40 T antigen in athymic (nude), anti-thymocyte serum-treated, and normal mice. 19 83

Inhibitory effects of adriamycin, daunomycin, actinomycin D and of the related DNA-complexes on DNA and RNA synthesis were compared by precursor uptake studies in Novikoff hepatoma cells, human mammary carcinoma cells and human leukemia cells. In addition, nuclear RNA labelling profiles were analyzed in human acute leukemia blast cells and nucleolar RNA synthesis was studied in Novikoff hepatoma cells in vitro after incubations of the tumor cells with adriamycin and DNA-adriamycin. The studies revealed that compared to the free drugs a) the DNA complexes were generally less active with respect to inhibition of overall DNA and RNA synthesis in these divergent tumor cell types, b) characteristic differences between adriamycin and daunomycin which are related to a more rapid cellular uptake of daunomycin were still present after complexing of both drugs to calf thymus DNA, and c) the intracellular mode of action of the free antibiotics was not changed by complex formation with DNA. These results indicate that a preferential incorporation of the macromolecular complexes into the tumor cells by pinocytosis--as originally postulated by Trouet et al. (1972)--is not likely for Novikoff hepatoma cells, human mammary carcinoma cells and human acute leukemia blast cells. In contrast, it may be concluded from this study that the DNA complexes dissociate already at the outer cell membrane resulting in a generally decreased but kinetically drug-specific cellular uptake. In a second communication it will be demonstrated that these in-vitro effects do not correlate with the therapeutic efficacy efficacy of the complexed drugs in vivo.
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PMID:Cytostatic efficacy of DNA-complexes of adriamycin, daunomycin and actinomycin D. I. Comparative studies in Novikoff hepatoma, human mammary carcinoma cells and human leukemic leukocytes. 19 10

Athymic BALB/c nude mice (nu/nu) fail to generate circulating antibodies to simian virus 40 (SV40) tumor (T) antigen when immunized with SV40-transformed mouse cells or with T antigen positive somatic cell hybrids derived from SV40-transformed human and normal mouse parental cells. However, normal BALB/c mice readily produce antibodies to SV40 T antigen. When nude mice were reconstituted with normal syngeneic T lymphocytes from spleen or thymus source, the humoral immune responsiveness to SV40 T antigen was restored.
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PMID:Antibody response to simian virus 40 tumor antigen in nude mice reconstituted with T cells. 19 68

The regulatory role of the adult thymus on the appearance of cytotoxic and suppressor T cells (thymus-derived lymphocytes) to allogeneic and autochthonous virus-induced tumors in mice was investigated. It was demonstrated that C57BL/6 mice challenged with allogeneic P815 mastocytoma cells and complete Freund's adjuvant failed to develop cytotoxic cells but instead developed suppressor T cells which inhibited cytotoxic T cell function. Further, adjuvant-induced suppressor cells prevented the primary in vitro induction of cytotoxic T cells to P815 mastocytoma cells. In contrast, adult thymectomized animals, when challenged with adjuvant and allogeneic cells, had a normal cytotoxic response in vivo and their cells could not inhibit the generation of cytotoxic T cells in vitro. These studies suggested that the intact adult thymus was necessary for the induction of suppressor cells. Moreover, suppressor cells regulated cytotoxic T cell activity both in vivo and in vitro. Further, it was shown that adjuvant could prevent the normal immune response to virus-induced tumors. BALB/c mice treated with murine sarcoma virus developed tumors which reached a maximal size by day 14 and then regressed. Sham thymectomized animals treated with virus and complete Freund's adjuvant to generate suppressor cells died from progressive tumor growth. In contrast, thymectomized animals similarly treated had normal regression of tumor and survived. These studies lead to the conclusion that the adult thymus may regulate immune responsiveness by the export of suppressor T cells which regulate other T cell responses to both allogeneic and tumor antigens.
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PMID:Suppressor cell regulation of immune response to tumors: abrogation by adult thymectomy. 19 28

Treatment of specifically sensitized MHA hamster lymphoid cells with rabbit antisera specific for hamster thymus-derived lymphocytes, in the presence of C, eliminated those cells capable of inhibiting the growth of syngeneic SV40 and methylcholanthrene tumors in vivo. Thymectomized, lethally-irradiated, bone marrow-reconstituted hamsters, shown to be devoid to T cell function, were, after attempted specific sensitization to the two syngeneic tumor cell lines, unable to reject either tumor by direct challenge in vivo. In addition, lymphocytes from such animals were incapable of inhibiting the growth of either tumor cell line in normal syngeneic recepients in the tumor cell neutralization assay. These data strongly support the conclusion that specifically sensitized thymus-derived lymphocytes are required for the rejection of syngeneic SV40 and methylcholanthrene tumors in inbred hamsters.
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PMID:Thymus-derived lymphocyte-dependent rejection of syngeneic papovavirus (SV40) and methylcholanthrene tumors in inbred hamsters. 19 67

Evolution of virus expression in different lymphoid organs as well as in solid syngeneic tumors of mice inoculated with an MuLV was studied with the aid of in vitro XC co-culture technique. When normal adult mice of strain XLII were inoculated intraperitoneally with a cultured Rauscher virus (RC), the virus could be detected, 10 days after inoculation, only in bone marrow in small amounts and thereafter no virus could be found in any of the organs tested, including bone marrow, spleen, thymus, lymph node and kidney. However, when age- and sex-matched parallel mice bearing syngeneic subcutaneous non-viral tumors were inoculated similarly with the RC virus, the virus could be detected abundantly not only in bone marrow and spleen but also in tumors during the first 3 weeks and even 6 weeks after virus inoculation. Transitional decrease or disappearance of the virus was observed around the 25th-31st day in organs and tumors of the inoculated mice. When the tumor mass was removed from these mice by surgery, the virus disappeared rapidly and definitely from all the organs tested. The virus recovered from in vitro explanted and cultured tumors, taken from mice inoculated with the virus, induced typical lymphoid leukemia in BALB/c mice inoculated as newborns. However, from certain aspects (hypertrophy of the thymus and lymph nodes), this virus was different from the original RC virus.
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PMID:Virus expression in different tissues of normal and tumor-bearing mice inoculated with a murine leukemia virus. 20 May 74


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