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Biomedical subjects

K Nemoto

Publications and source records attributed to K Nemoto.

At least 271 records · Page 15Linked to original sources
PubMed1986

Expression of the c-Ha-ras and c-myc genes in aflatoxin B1-induced hepatocellular carcinomas.

Expression and activation of several c-oncogenes in seven hepatocellular carcinomas from seven separate rats treated with aflatoxin B1 (AFB1) were examined by Northern and Southern blot analyses. Both c-Ha-ras and c-myc transcripts were elevated at high levels in all hepatomas. Moreover, in one of them, T2-1 hepatoma, the c-myc gene was amplified only in a tumor part of liver without significant rearrangement. N-ras specific transcripts were not elevated in these hepatomas. The present data suggest that the consistently increased expression or deregulation of the c-myc and c-Ha-ras genes may play an important role in the development of hepatomas induced by AFB1.

Aflatoxin B1↗
PubMed1986

Nature of leukemic stem cells in murine myelogenous leukemia.

We investigated the nature of myelogenous leukemic stem cells in mice. L-8057, a megakaryoblastic leukemia cell line used in this study, produces in vivo and in vitro colonies. By means of typical chromosomal aberrations in L-8057, one can conveniently detect the origin of the cells in each colony derived from a leukemic stem cell. Direct evidence of whether cells from each colony had leukemogenicity in recipient mice was successfully obtained by the colony transplantation assay. Both leukemic colony-forming unit-spleen (L-CFU-s) and leukemic colony-forming unit-culture (L-CFU-c) in L-8057 may have belonged to the same differentiating stage in the stem cells because of their similar radiosensitivity, although some parts of the L-CFU of L-8057 seemed to have lost their capability to regenerate L-CFU-s when the cells were plated in dishes. This leukemic stem cell preserves high self-renewal ability in vitro after 10 passages. In addition, in vitro colony formation by this leukemic cell during the above course of serial passages did not require any additional exogenous stimulators. The same sort of trials have been made on other types of leukemias. Leukemic stem cells showed remarkable variety in their response to stimulating factors and in their self-renewal activity, which suggests that they may have consisted of heterogeneous populations.

Animals↗
PubMed1986

Nucleotide sequence of the BamHI repetitive sequence, including the HindIII fundamental unit, as a possible mobile element from the Japanese monkey Macaca fuscata.

Clustered repeat units produced by BamHI digestion of genomic DNA from the Japanese monkey Macaca fuscata [JMr(BamHI)] were sequenced by dideoxy DNA sequencing. The nucleotide sequences of several individual repeats showed that the BamHI repeat contains the 170-bp HindIII element as an integral part, and that it has more than 90% homology with the HindIII repeat element [AGMr(HindIII)] found in the genomic DNA of the African green monkey. In the JMr(BamHI) repeat unit, the 170-bp HindIII element is flanked by a 6-bp inverted repeat, which is part of a 22-bp direct repeat. This latter repeat of 22-bp asymmetrically overlaps the border between the internal AGMr(HindIII)-like region and adjacent regions of the JMr(BamHI) repeat. A similar structural feature of the BamHI repeat unit has been found in the genomic DNA of the baboon, but not in that of the African green monkey. These results show clearly that the BamHI repeat of the modern Japanese monkey originated as a result of insertion of an AGMr(HindIII) element into a certain site(s) of the genomic DNA of an ancestor of the modern Japanese monkey before Macaca-Cercocebus divergence.

Animals↗
PubMed1986

Three types of swine immunoglobulin-producing tumours: lymphoplasmacytic lymphosarcoma, immunoblastic lymphosarcoma and plasmacytoma.

Three types of swine immunoglobulin-producing tumours are described. Case 1 was a lymphoplasmacytic lymphosarcoma, in which IgG was intracellularly identified in the plasmacytoid cells. Case 2 was an immunoblastic lymphosarcoma, the large cells of which possessed intracytoplasmic IgG and well developed RER. Case 3 was diagnosed as a plasmacytoma. There were two distinct immunoglobulins, IgG and IgA, in single plasmacytoid cells and the RER was highly developed. The origins of the three cases are discussed according to the theory of B-lymphocyte differentiation sequences and the origins of B-cell lymphomas. The mechanism of "double producers" is discussed with reference to DNA and RNA.

Animals↗
PubMed1986

Participation of interleukins in synergistic effect of Bu-WSA on concanavalin A-induced DNA synthesis in mouse splenic lymphocytes.

Butanol-extracted water-soluble adjuvant (Bu-WSA) obtained from Bacterionema matruchotii was mitogenic to murine splenic B lymphocytes, but not T lymphocytes. When murine splenic cells were cultured in the presence of Bu-WSA and concanavalin A (Con A) together, [3H]thymidine uptake of the culture cells synergically increased. The mechanism of the synergy of Con A and Bu-WSA and the participation of interleukin (IL) 1 and 2 in the synergy were studied. The proliferation cells in the synergy were Lyt-1+23- lymphocytes. Ia-positive accessory cells were required for the response. When separated cell populations and Marbrook-type culture vessels were used, a mixed cell population of T lymphocytes and B lymphocytes or macrophages (M phi) produced some active factor(s) after co-stimulation by Con A and Bu-WSA, and the factors enhanced DNA synthesis of another Con A-activated T lymphocyte population. Supernatants obtained from the spleen cell cultures or the mixed cell cultures with T lymphocytes and M phi in the presence of Con A and Bu-WSA contained greater amounts of IL-1 and IL-2 than those from cultures containing Con A or Bu-WSA alone. An addition of exogenous IL-1 or IL-2 to spleen cell cultures with Con A resulted in a proliferative response like that obtained through co-stimulation by Con A and Bu-WSA. These results suggest that the synergistic effect of Con A and Bu-WSA on the proliferative response in murine splenic cells is sustained by the enhancement of production of these T-lymphocyte growth factors.

Adjuvants, Immunologic↗
PubMed1986

The roles of interleukins in the synergistic effect of B-cell mitogens with concanavalin A on hydrocortisone-resistant thymic cell proliferation.

Investigations were made to determine the roles of interleukin (IL)-1 and IL-2 in the synergistic enhancement of DNA synthesis by concanavalin A (Con A) and bacterial lipopolysaccharide (LPS) or butanol-extracted water-soluble adjuvant (Bu-WSA) from Bacterionema matruchotii in cultures of thymic cells taken from hydrocortisone (HC)-treated C3H/HeN (LPS-responsive) and C3H/HeJ (LPS-non-responsive) mice. When the C3H/HeNCrj cells were cultured in the presence of Con A and LPS or Bu-WSA together, [3H]thymidine [( 3H]TdR) uptake of the cells was enhanced synergistically in comparison with those cultured with either one of the mitogens alone. The synergistic effect on thymic cells was dependent on Ia-positive accessory cells, since a previous treatment of the cells with anti-Iak serum and complement inhibited the response, and the inhibition could be relieved by the addition of either purified peritoneal exudate macrophages (Mø) or splenic B lymphocytes. The co-stimulation of cells with Con A and LPS or Bu-WSA also enhanced their production and release of thymic cell growth factor(s) into the culture medium. The amounts of IL-1 and IL-2 in the culture supernatants were sufficiently high to explain the activities of the growth factor(s). On the other hand, enhanced IL-2 production without significant increase in IL-1 was seen in the co-cultures of anti-Ia+ cell deprived thymic cells and purified splenic B cells prepared from C3H/HeNCrj mice in the presence of Con A and LPS or Bu-WSA, and it was seen in the cultures of C3H/HeJ thymic cells with Con A and LPS. These results suggest that the synergistic effect of Con A and LPS or Bu-WSA on the proliferative response of HC-treated thymic cells is mainly due to the enhanced production of IL-2 and its action to increase cell growth, and there are two pathways by which the enhancement of IL-2 production by Con A and LPS or Bu-WSA can occur: an IL-1-dependent pathway, or an IL-1-independent one.

Adjuvants, Immunologic↗
PubMed1986

Blast crisis of chronic myelogenous leukemia. Morphologic and immunological features.

The morphological and immunological features of 22 patients with transformation of Philadelphia chromosome (Ph1) positive chronic myelogenous leukemia (CML) were evaluated. Patterns of differentiation in blast crisis were as follows: myeloblastic 5 cases, lymphoblastic 6 cases, basophil differentiation 4 cases, monoblastic 3 cases, megakaryoblastic 1 case, and mixed 3 cases (myeloblastic and lymphoblastic, monoblastic and lymphoblastic and panmyelosis). Three cases were diagnosed as acute lymphoblastic leukemia (ALL) in early stage. After complete remission was achieved rapidly with vincristine and prednisolone, the hematological findings showed CML features. The immunological phenotype of lymphoblasts in lymphoid crisis was Ia+, CALLA+, surface and intracytoplasmic immunoglobulin negative. It was suggested that the neoplastic cells in two cases had B cell differentiation because of B1 or B4 positive. The terminal deoxynucleodidyl transferase (TdT) activity was examined by immunoperoxidase and immunofluorescence techniques on 11 cases. All TdT+ cells were the small lymphoid cells in 5 cases of lymphoid crisis and one case in mixed type. Heterogeneity of the terminal phase of CML was recognized. It was thus suggested that blast crisis of CML occurred in the pluripotent stem cell.

Blast Crisis↗
PubMed1985

Activation of c-myc gene transcription by Rous sarcoma virus infection.

Transcription of the c-myc gene in chick embryo fibroblast cells was activated 50- to 100-fold by Rous sarcoma virus (RSV) infection. More than 30-fold activation of c-myc gene transcription was also observed in RSV-transformed rat cells as compared with the control cells. The increased expression of c-myc gene in these cells was not due to gene amplification or gene rearrangement. This striking increase in expression of c-myc gene may be relevant to neoplastic transformation of RSV-infected cells.

Animals↗
PubMed1984

Radiation therapy of carcinoma in the rectum and sigmoid colon.

Radiation therapy combined with some anti-cancer drugs was performed in a total of 79 patients with carcinoma of the rectum and sigmoid colon, consisting of 41 primary, 25 recurrent and 13 postoperatively irradiated ones. Relief of subjective symptoms was observed in 50% or more of primary and recurrent patients. Radiation response of tumor was marked in 23 (56%) of primary ones. Five-year survival rate was 21% in the primary patients without any remote metastasis, 11% in the recurrent and 27% in the postoperatively irradiated. It was concluded that this combination therapy might be valuable for getting a cure in the primary patients with radioresponsive tumor (T1-T4: M0) and the patients with localized residual lesion, and for good palliation in the patients with far advanced and recurrent carcinoma.

Adenocarcinoma↗