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Query: UMLS:C0598766 (leukemogenesis)
 4,065 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The potential of embryonic thymus organ cultures for studies on relations of endogenous MuLV, lymphoid cells and thymic microenvironment to lymphoma development were evaluated. Four main findings are reported. First, thymuses of 14-day-old CBA and AKR embryos could be maintained in organ cultures for at least 9 weeks with sustained production of lymphocytes. Lymphopoiesis in CBA and AKR thymuses were not grossly different. Secondly, an indirect immunofluorescence (IF) technique demonstrated spontaneous appearance of MuLV-antigen-containing cells in AKR, but not in CBA thymuses. Such spontaneous MuLV expression first occurred after 16 days of organ culture, thereafter infrequently and at random in individual thymus cultures. Thirdly, incubation of AKR and CBA thymuses in lymphoma extract containing AKR-type MuLV at initiation of organ cultures induced MuLV-antigen-containing cells. These were first detected after 7-14 days in culture, somewhat earlier and initially more frequently in AKR than in CBA thymuses. In the former, induction was accompanied by a clear reduction in the number of lymphocytes per thymus. Fourthly, iododeoxyuridine (IdUrd) treatment of AKR thymuses on cultute day 0, 3 or 7 decreased the number of lymphocytes per thymus and induced appearance of MuLV-antigen containing cells, assayed 8-20 days later. The IdUrd effect was most marked on day 0, and decreased sucessively on days 3 and 7. IdUrd had a much slighter effect on CBA thymuses, causing a lower reduction in cell numbers and inducing few MuLV-antigen cells. These main results clearly demonstrate the potential usefulness of the organ culture system for studied on leukemogenesis. It may be directly applied to answer several questions raised by detailed findings in our study.
Int J Cancer 1977 Aug 15
PMID:Spontaneous and induced appearance of murine leukemia virus antigen containing cells in organ cultures of embryonic mouse thymus. 7 Apr 15

Trisomy of chromosome 15 is a highly regular feature of murine T-cell leukemogenesis. We have studied the chromosomal constitution of 7,12-dimethylbenza(a)anthracene (DMBA)-induced T-cell leukemias in C57BL X CBAT6T6 F1 mice. The CBAT6T6-derived chromosome T(14:15)6 was regularly duplicated whereas the C57BL-derived normal chromosome 15 was only present in one copy. It was concluded that the gene(s) that tend to duplicate in parallel with the neoplastic transformation of the prothymocyte to an overt leukemic cell have a greater chance of duplicating and/or may have a stronger promoting effect on leukemogenesis if stronger promoting effect on leukemogenesis if located on the CBA-derived, structurally rearranged T(14:15)6 than the corresponding genes located on the C57BL-derived normal chromosome 15.
Int J Cancer 1979 Apr 15
PMID:Non-random duplication of chromosome 15 in murine T-cell leukemias induced in mice heterozygous for translocation T(14:15)6. 10 28

Cyclic adenosine 3':5'-monophosphate (cyclic AMP) levels were slightly increased in preleukemic AKR mouse thymus cells, compared with nonleukemic thymus cells, but were markedly reduced in leukemic cells. Adenylate cyclase activity rose during the preleukemic and leukemic phases of leukemogenesis. Although the drop of epinephrine-induced stimulation of thymus adenylate cyclase in the preleukemic phase was probably age related, there was an additional decrease of adenylate cyclase activation by epinephrine in leukemic cells. Cyclic AMP phosphodiesterase activity was slightly higher in preleukemic cells and more than fourfold AKR thymus. These observations suggest that cyclic AMP phosphodiesterase is largely responsible for the low levels of cyclic AMP in leukemic cells. Significant changes in cyclic AMP metabolism are already detectable before neoplastic cells may be found in the thymus.
Cancer Res 1975 Sep
PMID:Changes in lymphoid cyclic adenosine 3':5'-monophosphate metabolism during murine leukemogenesis. 16 59

Sixty-seven specific-pathogen-free cats of various ages (newborn, 2 wk, 1 mo, 2 mo, 4 mo, and 1 yr) were inoculated ip with either the Rickard (R) or the Kawakami-Theilen (KT) strain of feline leukemia virus (FeLV). Susceptibility to FeLV was judged by induction of a) FeLV group-specific antigens (gsa) in leukocytes, b) FeLV-related disease, c) antibody to feline oncornavirus-associated cell membrane antigen (FOCMA), and d) virus-neutralizing (VN) antibody. Susceptibility to FeLV-decreased with age. Persistent viremia and FeLV-related disease developed in 100% of cats inoculated as newborns, in 85% of cats inoculated at 2 weeks to 2 months of age, and in 15% of cats inoculated at 4 months or 1 year of age. Cats susceptible to FeLV leukemogenesis became persistently FeLV gsa-positive (viremic) at 4 weeks post inoculation and thereafter and produced little or no FOCMA or VN antibody. Cats that resisted leukemogenesis by FeLV all developed persistent FOCMA and VN titers and never became FeLV gsa-positive. The disease in inoculated cats was influenced by virus strain; FeLV-R induced predominantly thymic lymphosarcoma, whereas FeLV-KT caused fatal nonregenerative anemia without concurrent neoplasia.
J Natl Cancer Inst 1976 Aug
PMID:Feline leukemia virus infection: age-related variation in response of cats to experimental infection. 18 71

Membrane markers of feline T- and B-lymphocytes were identified for further investigation of leukemogenesis in the cat. Feline T-cells formed spontaneous erythrocyte rosettes with guinea pig (GPE) and rat erythrocytes (RE). The receptors for GPE and RE were separate entities and expressed independently on lymphoid cell membranes. The RE receptor appeared to be present only on more mature or differentiated T-cells, whereas the GPE receptor reacted with a broader population that included less differentiated T-cells. Feline B-cells bore a complement receptor that was detected by adherence of SE coated with antibody and complement. Malignant lymphoblasts obtained from thoracic fluid of cats with feline leukemia virus (FeLV)-induced thymic lymphosarcomas, as well as FL-74 cells (a FeLV-transformed feline lymphoblastoid cell line) expressed T-cell markers. These results provided definitive evidence for markers of feline T- and B-cells and identified an experimentally induced T-cell lymphosarcoma.
J Natl Cancer Inst 1976 Oct
PMID:Characterization of feline T-and B-lymphocytes and identification of an experimentally induced T-cell neoplasm in the cat. 18 81

Mitogen-induced blast transformation of peripheral blood lymphocytes and quantitative changes in circulating T- and B-cells were studied serially in cats inoculated with feline leukemia virus (FeLV). Concanavalin A-induced blast transformation sharply declined beginning at 5 weeks post inoculation (Pl) in FeLV-infected cats when compared to age-matched uninfected control cats. Similar but less consistent changes were seen in responses to pokeweed mitogen-induced stimulation. In most infected kittens this defect persisted until they died from thymic lymphosarcoma, 15-24 weeks Pl. An early lymphopenia, due primarily to a decrease in circulating B-cells, occurred in infected cats 5-8 weeks Pl. Following a return of total and B-lymphocytes to control values, infected cats developed increased numbers of T-cells at 16 or more weeks Pl, which correlated with circulating lymphoblastic lymphocytes bearing T-cell markers. These results correlated neoplasia arising in a thymus-derived lymphocyte population with mitogenic hyporeactivity in the preneoplastic period and suggested that FeLV-induced immune alterations may be a necessary antecedent of leukemogenesis in the cat.
J Natl Cancer Inst 1976 Nov
PMID:Lymphocyte mitogen reactivity and enumeration of circulating B- and T-cells during feline leukemia virus infection in the cat. 18 90

The purpose of this study was to develop an animal system of protective immunity against oncornaviruses and to test whether such immunization had an inhibitory effect upon chemical sarcomagenesis. Several murine sarcoma virus (MSV) pseudotypes were used as immunogens and tested against themselves, against other pseudotypes, against leukemogenesis by their helper viruses, and against sarcomagenesis by 3-methylcholanthrene. Five MSV pseudotypes were obtained by rescuing complete MSV from MSV-genome carrier, nonproducer hamster tumor cells, using five different leukemia viruses as helpers. The immunogenic properties of these pseudotypes could be specified on the basis of the following observations. 1) They all induced sarcomas in newborn mice and regressing sarcoma nodules in young adult mice. After regression, most mice remained free of neoplastic disease, but some developed sarcoma or leukemia relapses. 2) They had an individual host range pattern, usually determined by the helper virus, as tested by inoculation of a constant virus dose in BALB/c, C57BL/Ka, and Swiss mice. 3) They were all immunogenic, in the sense that the first virus inoculation prevented sarcoma induction by a second challenge, either viral or cellular. 4) They were cross-reactive in vivo, one pseudotype immunizing against another, in the combinations tested. 5) They were able to immunize against leukemogenesis induced by their helper viruses. This was shown by prevention of leukemic deaths by Rauscher and Friend viruses, by a slight prolongation of survival after challenge with the Precerutti-Law leukemia virus, and by inhibition of splenomegaly by Moloney leukemia virus. In a second stage of the study, we investigated whether immunization with any of the MSV psuedotypes had an inhibitory effect upon sarcomagenesis induced by near-threshold doses of 3-methylcholanthrene. The incidence of these sarcomas was essentially the same in virus-immunized and control mice. It was concluded that immunizing procedures able to prevent sarcomagenesis when the inducer is a virus did not have any consistent preventive effect when the inducer was a chemical.
Cancer Res 1977 Jun
PMID:Murine sarcoma virus pseudotypes used as immunogens against viral and chemical oncogenesis. 19 61

The effect of serum from 12 cats with lymphosarcoma induced by feline leukemia virus (FeLV) on the response of normal cat peripheral blood lymphocytes to phytomitogen-induced blastogenesis was studied. The majority of FeLV sera, when tested at a concentration of 20% of the incubation medium, caused a 40 to 70% reduction in the mean blastogenic response to concanavalin A compared to the response obtained with a similar concentration of normal feline serum. Results with pokeweed mitogen were similar, but the depression in blastogenesis was less than with concanavalin A. Further studies showed that the blastogenic inhibitory activity of FeLV serum (a) was heat labile at 56 degrees for 30 min, (b) could not be overcome by greater concentrations of mitogens, (c) was proportional to the concentration of FeLV serum in the incubation medium, and (d) could not be demonstrated when lymphocytes were preincubated in FeLV serum followed by washing and reincubating in normal feline serum. The results suggested that a substance present in the serum of FeLV-infected cats contributes to altered immunological reactivity during leukemogenesis in the cat.
Cancer Res 1977 Nov
PMID:Inhibition of normal lymphocyte mitogenic reactivity by serum from feline leukemia virus-infected cats. 19 25

Repeated percutaneous applications of 7,12-dimethylbenz(a)anthracene on weaning DBA/2 and ST/a mice induced 100% leukemias with short latency periods. Endogenous C-type viruses were activated during the treatment as evidenced by (a) increased expression of the murine leukemia virus major core protein, p30, in blood and spleens and (b) increased frequency of detection of ecotropic virus by cocultivation of the splenocytes with SC-1 cells. The treatment did not affect p30 expression in several nonlymphoid organs, and detection of xenotropic viruses in the splenocytes was decreased. Virus expression did not correlate with the progression of disease in that (a) high p30 levels were generally found in mice with relatively low spleen weights and (b) p30 levels had no obvious connection to survival of the individual. 7,12-Dimethylbenz(a)anthracene treatment had little influence on p30 expression in spleens and blood from C3H and BALB/c mice, which are less sensitive to 7,12-dimethylbenz(a)anthracene-induced leukemogenesis. The results indicate an association of C-type virus activation with chemical induction of leukemia but do not necessarily imply an etiological role of the virus in the disease.
Cancer Res 1978 Mar
PMID:Activation of C-type virus during chemically induced leukemogenesis in mice. 20 89

A case of acute lymphoblastic leukemia (ALL) with a near-haploid (27 chromosomes) leukemic cell population in the marrow has been described and the findings compared to those of the only other such case in the literature. In both cases the cells with 27 chromosomes, except for one chromosomal group, had karyotypic findings which were identical. Cells with 54 chromosomes, karyotypically exact duplicates of the cells with 27 chromosomes, were also encountered; on morphological basis it appeared that the marrow contained large and small lymphoblasts, possibly matching the metaphases with 54 and 27 chromosomes, respectively. The genesis of the cells with 27 chromosomes was uncertain and several postulates are discussed, as well as the relation of the findings to the cytogenetic observations encountered in ALL and their possible role in human leukemogenesis.
Cancer 1977 Sep
PMID:Chromosomes and causation of human cancer and leukemia. XXIII. Near-haploidy in acute leukemia. 26 95


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