1,720,963 research outputs found
Immunological cross-reactivity between H-2Dk product and DTIC-treated H-2d lymphoma
No full textThe experiments reported here concern the characterization by techniques of in vitro cell-mediated immunity of the antigens induced by 5-(3,3' dimethyl-1-triazine)-imidazole-4-carboxamide (DTIC) on L1210, a chemically-induced lymphoma of DBA/2 mice (H-2d). This series of experiments with the DTIC-treated L1210 tumour show the presence of an 'H-2D'-like antigen which resembles the Dk gene product/s of the H-2k haplotype
Changes in H-2 antigen expression on a murine spontaneous leukaemia (K36) detected by cell-mediated cytotoxicity assay
No full textCellular cytotoxicity experiments were done to test the potential of the extra H-2 antigenic specificities on the K36 spontaneous leukaemia as targets. In addition, experiments were performed to rule out the possibility that the target determinants could be normal cross-reacting alloantigens, e.g., T1, Qa, non-H-2 and previously undetected H-2 public specificities, which are more readily detectable on tumours than on normal cells. We used F1 hybrid mice, in which one parent was of the strain of origin of the tumour (K36) and the other parent of the B10 congenic series, i.e., (AKR x B10)F1. These cells were stimulated by lymphoid cells from other B10 congenic strains, B10.A and B10.D2, and tested against the test tumour K36 and several PHA blast controls. Several K36 sublines as well as a cloned line of K36 (K36.16) were used and significant cytotoxicity against an H-2(d)-like target on these tumour cells was obtained. These data exclude the possibility of a cross-reactive alloantigen, e.g., undetected H-2 public specificity, or differentiation antigens. These results with the K36 tumour were consistent with our immunochemical studies (see Schmidt & Festenstein, 1980) and were confirmed and extended by cold target inhibition experiments. In these experiments, B10.BR cells were sensitized by B10.D2 lymphoid cells and tested against B10.D2(51chromium-labelled PHA blasts). Two kinds of normal unlabelled lymph node suspensions as well as the K36.16 tumour cell suspension were used. Significant specific inhibition of between 19% and 40% was obtained using K36 and between 23% and 37% using B10.D2 (positive control). AKR cells (negative control) in contrast were unable to reduce the percentage specific cytotoxicity. Since it was already known that the H-2K(k) gene products are missing from this tumour (Schmidt & Festenstein, 1980), it was of interest to test whether cytotoxic effectors directed against the H-2k(k) gene products were able to kill the K36 tumour. Accordingly, B10.D2 lympoid cells were sensitized to B10.BR (C3H.OH) and B10.A targets, respectively, and tested against K36 and appropriate controls. Only weak killing was observed when sensitization was effected against the K end of the H-2(k) haplotype (i.e., using B10.A as the sensitizing cell) but strong and significant cytolysis was found when the sensitization was against the whole H-2(k) haplotype or against the H-2D(k) gene product. These results were confirmed by cold target inhibition studies. These experiments provide further indications for the H-2(d)-like characteristics of these allodeterminants. We have already excluded some of the possible explanations for these findings (i.e., cross-reactions with H-2 and non-H-2 normal specificities). The cold target inhibition experiments rule out non-specific viral effects. Thus, we favour an alteration in regulatory genes leading to repression of the H-2K(k) product and derepression of the H-2D(d) product, but cannot formally rule out highly cross-reactive H-2-like virally encoded determinants
Biologic effects of the altered MHS profile on the K36 tumor, a spontaneous leukemia of AKR
No full textInhibition of tumor cell proliferation by linear polyunsaturated aldehydes
No full textSerious disorders such as cancer, heart diseases and degenerative eye diseases can be partly prevented by the use of carotenoids. The mechanisms of action have been identified mainly in the antioxidant effects and in the regulation of certain processes of the immune system. These findings have stimulated intensive studies of the role of carotenoids and their derivatives, including polyunsaturated preparations, of which the compound 2,4,6-transoctatrienale exhibited the most significant biological activity. Lymphoid cells grown in suspension were inhibited more efficiently than mammary cell lines grown in monolayer. At 100 μg/ml the lymphoid cells were significantly inhibited in contrast with human mammary MCF-7 cells and human neuroblastoid SHSY5Y cells, which were not affected at these concentrations. A lower amount of the preparation did not inhibit the rate of cell growth or produce cytotoxic activity. The data reported herein indicate that the compound 2,4,6-transoctatrienale, the most effective antioxidant compound within a number of polyunsaturated linear aldehydes, is endowed with potent cytotoxic activity in cell cultures and that further experimental animal studies are warranted
Monoclonal antibody against human growth hormone receptor
No full textGHR shows a high degree of homology with the prolactin receptor and with the other receptors that belong to the hemopoietic receptor superfamily. This paper describes a monoclonal antibody (MAb) (2B4B6) specific for both the extracellular domain of human GHR and human growth hormone (GH) binding protein. Mice were immunized against a seven-aminoacid peptide sequence screened by FASTA (sequence similarity search served by Genome-Net) from the European Bioinformatics Institute to exclude the existence of human membrane proteins with significant sequence homology. MAbs were screened against the peptide sequence and 2B4B6 was selected for its capability to recognize the full-length hGHBP. As evaluated by both enzyme-linked immunoadsorbent assay (ELISA) and FACS analysis, this MAb seems to recognize and bind to a hGHR positive cell line, IM-9, as well as a murine cell line, BaF3 (8/6), transfected with a chimeric construct, hGHR/hG-CSFR and expressing hGHR on the cell membrane. Studies investigating the biological effects of this MAb showed that anti-hGHR mediated inhibition of cell proliferation was not due to competition with GH binding but rather to prevention of receptor dimerization. Because of its specificity, this MAb may be usefully applied in situations in which GHR and receptors with a high degree of homology, such as PRLR (prolactin receptor), are expressed simultaneously, as occurs in the immune system
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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