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Biomedical subjects

G Klein

Publications and source records attributed to G Klein.

At least 829 records · Page 46Linked to original sources
PubMed1981

Diploid human lymphoblastoid and Burkitt lymphoma cell lines: susceptibility to murine NK cells and heterotransplantation to nude mice.

Human lymphoid cell lines which had been classified on the basis of studies on clonality and morphological, on the basis of studies on clonality and morphological, chromosomal and functional parameters as lymphoblastoid cell line (LCL) of presumed non-neoplastic origin and Burkitt lymphoma (BL) lines of proven malignant origin, were tested for susceptibility to natural killer (NK) cells obtained from the spleens of athymic nude mice. The 20 lines included normal diploid LCL and aneuploid BL lines. All cells carried the Epstein-Barr virus (EBV) genome. In addition, two EBV-negative BL lines were tested. The pronase-induced release of 14C-DNA from 14C-thymidine-labelled target cells was used to assess the sensitivity of the cell lines to NK activity. When attempts were made to correlate the growth of the EBV-positive LCL and the EBV-positive BL cell lines in the subcutaneous space of adult nude mice with their susceptibility to NK cells, no significant correlation was observed. The EBV-negative BL cell line, Ramos, however, could be transplanted subcutaneously in nude mice and was more resistant to NK activity than was the EBV-negative BL cell line, BJAB, which cannot be transplanted subcutaneously. Growth of heterotransplanted EBV-converted cell lines in the subcutaneous space of adult nude mice may be influenced by immune effectors other than NK cells.

Animals↗
PubMed1981

Activation of the Epstein-Barr virus genome by 5-aza-cytidine in latently infected human lymphoid lines.

Recent studies indicate that gene expression in higher eukaryotes is accompanied by a decrease in the frequency of 5-methyl cytosine residues around the activated site (Razin and Riggs, 1980). 5-aza-cytidine (5-aza-C) is an analogue that reduces cytidine methylation in DNA (Jones and Taylor, 1980) and has been reported to change the differentiation pattern of cultured mouse embryo cells (Taylor and Jones, 1979). We have tested its ability to activate the Epstein-Barr virus cycle in latently EBV-infected human lymphoid lines. After an incubation period of 6 to 8 h with the drug, early antigens (EA) were induced in a substantial fraction of the cells in all six lines tested that had a low rate of spontaneous viral antigen production. Optimal conditions for EA induction were defined. The efficiency of 5-aza-C was comparable to the inducing effect of iododeoxyuridine. EBV-DNA and EBNA positive virus-non-producer lines did not respond to 5-aza-C treatment. The findings are discussed in relation to the possibility that changes in EBV-gene expression may be related to the state of DNA methylation.

Antigens, Viral↗
PubMed1981

Epstein-Barr virus co-reconstituted with Sendai virus envelopes infects Epstein-Barr virus-receptor negative cells.

Epstein-Barr virus (EBV) was co-reconstituted with Sendai virus envelopes. The reconstituted "hybrid' virus could bind and penetrate into EBV-receptor negative cells. Using this approach, T-cell-derived human and mouse leukemia cells, human T-lymphocytes and mouse spleen cells were successfully infected as judged by the induction of EBV-determined antigens and stimulation of DNA synthesis. The T-cell-derived human leukemia line Molt-4, that can absorb EBV but without virus penetration, could be also infected by the reconstituted EBV.

Animals↗
PubMed1981

Moloney virus (M-MuLV) leukemogenesis: virus spread, antibody production and antigenic expression in neonatally virus-inoculated young mice.

(A X C57BL) and (A X C57L)F1 hybrid mice were inoculated neonatally with M-MuLV. Virus spread, antigenic expression and antibody production were followed during the preleukemic period. M-MuLV was first detectable in the spleen and later in the thymus. Virus spread was faster and the level of viremia higher in A X C57L than in A X C57BL mice. Also, A X C57L mice had no or only low titers of virus neutralizing antibodies, whereas A X C57BL mice had high titers. Anti-MCSA antibodies, reacting with the surface of syngeneic M-MuLV-induced lymphoma cells, were present in a minority of the mice, but disappeared ultimately in all mice. The two groups of mice differed with regard to the length of the preleukemic latency period. High virus load and a low level of virus neutralizing and anti-MCSA antibodies were correlated with an earlier onset of leukemia.

Animals↗
PubMed1981

Difference in viral binding between two Epstein-Barr virus substrains to a spectrum of receptor-positive target cells.

Radio-labelled Epstein-Barr virus (EBV) was utilized in a direct binding assay to detect the presence of EBV receptors. The sensitivity of this method was affirmed by the detection of EBV-receptors on three EV-carrying cell lines that have previously been reported as receptor negative. Two laboratory substrains of EBV, derived from the cell lines B95-8 and P3HR-I (designated B and P virus respectively), were tested in the binding assay. The main repcptor prototype adsorbed both viral strains without apparent distinction. In contrast, two lines, a Swedish EBV-negative B-cell lymphoma (U698) and a virus non-producer subline of the receptor-negative P3HR-1 line, adsorbed P virus selectively but failed to adsorb B virus.

Binding, Competitive↗
PubMed1981

Photoaffinity labeling of mitochondrial adenosine triphosphatase by an azido derivative of the natural adenosine triphosphate inhibitor.

The natural mitochondrial ATPase inhibitor (IF1) was modified with a radioactivity labeled heterobifunctional and photosensitive reagent, methyl 4-azido(14C)benzimidate ((14C)MABI). Titration experiments of IF1 by (14C)MABI and tryptic maps of (14C)MABI-IF1 indicated that specific lysine residues in IF1 are preferentially labeled by (14C)MABI. Under appropriate conditions of labeling (1 to 2 lysine residues modified per IF1), MABI-IF1 exhibited the same inhibitory potency as native IF1 on the hydrolytic activity of the coupling factor 1 of mitochondrial ATPase (F1). The same conditions were required for inhibition of F1 by MABI-IF1 and IF1 (slightly acidic pH and presence of ATP and MgCl2). In photolabeling experiments, (14C)MABI-IF1 was used to investigate the localization of IF1 binding sites on F1. Upon photoirradiation, MABI-IF1 bound selectively to the beta subunit of soluble or membrane-bound F1. Adenylyl imidodiphosphate and quercetin, two compounds which partially mimic the inhibitory effect of IF1 on ATPase activity of F1, markedly prevented the binding of (14C)MABI-IF1 to F1; on the other hand, aurovertin, a specific ligand of the beta subunit of F1, did not affect the interaction between (14C)MABI-IF1 and F1. In the absence of light, (14C)MABI-IF1 was used as a reversible radiolabeled ligand with respect to membrane bound F1 to investigate F1-IF1 interactions to inside-out submitochondrial particles as a function of the energy state of the particles. Oxidation of NADH by submitochondrial particles resulted in a decrease of bound (14C)MABI-IF1; the effect was counteracted by antimycin. The data suggested that added (14C)MABI-IF1 is capable of exchanging with IF1 bound to F1 in submitochondrial particles and that the rate and extent of (14C)MABI-IF1 release are triggered by the proton-motive force developed by the particles.

Adenosine Triphosphatases↗
PubMed1981

Epstein-Barr-virus-carrying lymphoma in a patient with ataxia-telangiectasia.

An undifferentiated lymphocytic lymphoma of mesenteric lymph nodes occurred in a young boy with ataxia-telangiectasia. Two independent tests, Epstein-Barr virus (EBV)-cRNA/DNA hybridisation and EBV DNA/DNA reassociation kinetic analysis, showed 53 and 68 EBV genome equivalents per cell respectively, which was compatible with an EBV-genome-carrying tumour. Whether this was a polyclonal lymphoproliferation or a monoclonal tumour could not be determined owing to lack of suitable material. The presence of EBV genomes should be sought in lymphomas arising in ataxia-telangiectasia and other immunodeficiencies.

Abdominal Neoplasms↗
PubMed1981

Chromosome 15 trisomy in spontaneous and carcinogen-induced murine lymphomas of B-cell origin.

G-banding analyses of 14 independently derived B-cell lymphomas showed the frequent occurrence of chromosome 15 trisomy. It was present in seven of nine spontaneous B-cell lymphomas, but in company with other trisomies, monosomies and marker chromosomes. In five carcinogen-induced primary B-cell leukemias, trisomy 15 was the dominating change. Taken together with the previously demonstrated importance of chromosome 15 trisomy for T-cell leukemogenesis and of the 12;15 translocation in plasmacytogenesis in the mouse, it appears likely that the distal part of chromosome 15 carries a cluster of genes, perhaps a supergene region, that may play an important role in the differentiation and/or the normal responsiveness of various lymphoreticular cell types to growth control.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1981

Malignant cells isolated from Burkitt's lymphoma but not other forms of leukemia activate the alternative complement pathway in human serum.

Cells isolated directly from primary biopsies of Burkitt's lymphoma were found to activate the alternative complement pathway in hypogammaglobulinemic human serum. In contrast, cells isolated from patients with either acute lymphoblastic leukemia, chronic lymphocytic leukemia or chronic myeloid leukemia did not activate. No defects in the ability of Burkitt's lymphoma sera to support alternative pathway activation were detected.

Burkitt Lymphoma↗
PubMed1981

Implantation of mouse histocompatibility antigens into membranes of cultured tumor cells.

Membranes of murine lymphoma cells expressing H-2a antigens were isolated, purified and co-reconstituted with isolated Sendai virus envelopes according to a previously published procedure (Volsky, D.J. et al., Proc. Natl. Acad. Sci. USA 1979. 76: 5440.). The resulting hybrid H-2a/Sendai virus envelope vesicles (SH-2a vesicles) were capable of binding to and fusing with mouse lymphoma cells. The fusion resulted in the implantation of H-2a antigens into membranes of target cells, as demonstrated by the presence of serologically active antigens on cultured cells 8 and 16 h after implantation.

Animals↗
PubMed1981

Incidence and type of tumors induced in C57BL bg/bg mice and +/bg littermates by oral administration of DMBA.

As an attempt to study the effect of the beige (bg) mutation on chemical carcinogenesis, 65 C57Bl/bg/bg mice and 83 +/bg littermate controls received DMBA in five weekly intragastric doses. The incidence of tumors of different histological types was monitored through observation periods ranging between 165 and 500 days. By 165 days after the first DMBA feeding, 18% of the +/bg and 31% of the bg/bg mice had developed tumors. The beige mice had a higher incidence of epithelial and non-epithelial tumors arising in cutaneous or subcutaneous sites than the controls. The total incidence of lymphomas was similar in the two groups. However, lymphomas appeared somewhat earlier in beige than in control mice. Altogether 33 +/bg and 27 bg/bg mice were followed for 500 days. By this time, 73% of the +/bg and 78% of the bg/bg mice had developed tumors. The beige group showed a higher incidence of non-thymic lymphomas than the controls. In contrast, the incidence of thymic lymphoma, cutaneous epithelial tumors and bile-duct adenomas was similar in the two groups or higher in +/bg that in bg/bg mice. The results suggest that the bg mutation causes a certain defect in a mechanism that may prevent or delay the onset of non-thymic lymphomas and of epithelial and non-epithelial cutaneous tumors in DMBA-treated mice. The differences between the two groups were smaller than those previously reported in relation to the increased susceptibility of beige mice to certain transplanted tumors, attributed to the known defect in natural killer (NK) activity in the beige mice. The reduced differential in the DMBA system may be due to the partial reduction of NK activity, induced by the carcinogen, as reported previously (Ehrlich et al., 1980) and confirmed in the present study.

9,10-Dimethyl-1,2-benzanthracene↗