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Biomedical subjects

R Ber

Publications and source records attributed to R Ber.

At least 55 records · Page 3Linked to original sources
PubMed1982

Hybridization between a human epithelial line, infectable by Epstein-Barr virus, and Burkitt lymphoma lines: membrane properties, superinfectability, inducibility and tumorigenicity.

The human epithelial line U, which is partially infectable with EBV, was hybridized with the EBV-genome carrying Burkitt lymphoma lines P3HR-1 and Daudi. Authenticity of the hybrids U-Put and U-Dut was established by isoenzyme studies. Although the two hybrids carried the EBV genome derived from the lymphoma parent, being 100% positive for Epstein-Barr-virus-associated nuclear antigen (EBNA), they resembled the U parent in many respects: they were deficient for membrane immunoglobulins and Fc receptors, and had a lower concentration of EBV-C3 receptors than either parent. Unlike the P3HR-1 parent, U-Put hybrid was nonpermissive for both the EBV cycle antigens, early antigen (EA) and viral capsid antigen (VCA). The inducing agent 12-O-tetra-decanoyl-phorbol-13-acetate (TPA) caused distinct viral early antigen synthesis (EA) in U-Put, lower, however, than that of the parental P3HR-1. U-Dut was completely nonpermissive and noninducible for early and viral capsid antigens. Thus, even an epithelial parent infectable by EBV restricted, although not completely, expression of EBV antigens, with the exception of EBNA. It has been suggested that EBNA is an autonomous function of the viral genome, independent of host cell control; the latter regulates expression of antigens related to viral cycle. The hybrids U-Put and U-Dut resembled the U parent also in regard to growth in soft agar and tumorigenicity in nude mice, although in this respect the lymphoma parental properties were not completely eclipsed.

Animals↗
PubMed1982

Truncated mu chain in a Burkitt lymphoma line (P3HR-1) and its fate in various hemapoietic somatic cell hybrids.

Hybrids obtained by the fusion of PUT, an ouabain and TG-resistant subline of the Burkitt lymphoma(BL)-derived P3HR-1 line, with hemopoietic cells of various differentiation types were tested for their membrane and intracellular immunoglobulin expression. PUT cells carry no membrane immunoglobulin, but contained intracellular 61K mu chain and kappa chain. The PUTKO-1 hybrid, derived from the fusion of PUT with the erythroleukemia line K562 contains no detectable immunoglobulin. NAMPUT, a hybrid between PUT and the IgM-lambda-producing BL line Namalwa, synthetizes cellular mu, lambda and kappa chains, but its surface-Ig is exclusively mu-lambda. Two different mu chains could be detected, both precipitated by either anti-mu or anti-lambda sera. Immunoprecipitation with anti-kappa precipitated neither kappa nor mu. PUTRAL was derived by fusing PUT with Rael, an unusual surface-IgG-lambda-carrying BL line. In this hybrid, the ability to synthesize gamma and lambda chains has been eclipsed, but two mu chains are present: one corresponding to the truncated 61K chain of PUT, and a normal-sized 74K. Between 20 and 30% of the cells stain for surface IgM.

Autoradiography↗
PubMed1982

Human lymphoma-lymphoma hybrids and lymphoma-leukemia hybrids. I. Isolation, characterization, cell surface markers, and B-cell markers.

Four new somatic cell hybrids were obtained by fusion of various Burkitt's lymphoma (BL)-derived cell lines that had different selective markers: Raji-P3HR-1, Daudi-Raji, and a P3HR-1-P3HR-1 "autohybrid" derived from two P3HR-1 sublines. In addition, a hybrid was obtained between the Daudi (BL) line and the human leukemia cell line K562. The hybrids were extensively characterized by means of chromosome, isozyme, and HLA surface markers. The phenotypic differences between the parent cell lines allowed some conclusions with respect to the expression of latent Epstein-Barr virus (EBV) genomes, C3 and EBV receptors, and of immunoglobulin and beta 2-microglobulin-HLA expression as well as the influence of the leukemia cell (K562) genome on B-cell properties in the Daudi-K562 hybrid. B-cell and differentiated markers of these hybrids were characterized. High-level expression dominated for the marker C3 and EBV receptors, which showed a good correlation coefficient of 0.84, as was true for Fc receptors and surface immunoglobulin. The Daudi-K562 hybrid showed loss of all B-cell markers but retention of the leukemia cell markers (e.g., hemoglobin synthesis).

Animals↗
PubMed1982

Human lymphoma-lymphoma hybrids and lymphoma-leukemia hybrids. II. Epstein-Barr virus induction patterns.

In addition to the spontaneous expression of markers of the early and late phases of the viral cycle [Epstein-Barr virus (EBV), early viral cycle antigens (EA), and viral capsid antigen (VCA)] by a Panel of hybrid cell lines derived by fusion of human hematopoietic cell lines, the induction of these markers by three chemical inducers [5-iodo-2'-deoxyuridine, the tumor promoter 12-O-tetradecanoylphorbol 13-acetate (TPA), and sodium butyrate] were analyzed. A variant of the prototype producer of lytic EBV, P3HR-1 (PICAT) was observed to show consistent low spontaneous and induced production of EA and VCA as compared to the P3HR-1 line from which it was derived. An "autohybrid" (PICATPO-1) between these two lines showed a low production of VCA. Hybrids between Raji and P3HR-1 sublines (RUD-PICAT-1 and RUDPUT-2) showed reduced expression of EBV antigens. Both hybrids were capable of VCA expression, in contrast to the Raji parent that expressed EA but not VCA. A new Raji-Daudi hybrid (DITRUD-1) expressed spontaneous and induced EA and VCA at levels intermediate between its two parents. A different type of hybrid was derived from a Daudi subline and the K562 leukemia cell line (DUTKO-1) and was found to be capable of spontaneous as well as induced EA and VCA expression. Both DUTKO-1 and DITRUD-1 were similar to Daudi in their induction profile in respect to a very low response to TPA.

Animals↗
PubMed1982

Nonimmunogenic radiation-induced lymphoma: immunity induction by a somatic cell hybrid.

The cell line designated PIR-2 is a nonimmunogenic X-ray-induced thymoma of C57BL/6 origin that is unable to induce antitumor immunity in syngeneic lymphocytes in vitro and in mice in vivo. Fusion of PIR-2 with an allogeneic "universal fuser" A9HT (clone 3c) resulted in the establishment of a somatic cell hybrid designated A9/PIR. C57BL/6 lymphocytes sensitized in vitro with A9/PIR could lyse parental PIR-2 cells, as well as other syngeneic tumors. However, immunization of mice with the hybrid significantly enhanced PIR-2 tumor takes while it partially protected the animals against a challenge with unrelated syngeneic tumors. The results imply that somatic cell hybridization can increase the immunogenicity of an otherwise nonimmunogenic tumor. However, in view of the enhancing effects of hybrid preimmunization on parental tumor cell growth, the possible application of this approach for immunotherapy is questionable.

Animals↗
PubMed1981

Membrane-bound and cellular immunoglobulins in human B-lymphoma lines and derived hybrids.

Hybrids derived from the fusion of cell lines representing different maturation stages were studied for their membrane and cellular immunoglobulin expression. The hybrids can be subdivided into 3 groups, with one common parental line in each group. In the first group, Raji cells represent the common parent: it contains small amounts of membrane and cytoplasmic mu (mu) and kappa (kappa) chains. In the second group, PUT is the common parent, an ouabain and TG-resistant subline of the BL-derived P3HR-1 line. PUT contains a truncated intracellular mu chain. The third group consists of hybrids between K562, an EBV-negative human erythroleukemia line and 2 different BL lines. Membrane-immunoglobulin expression was intermediate between the parental lines in the first two groups derived from the fusion of 2 BL lines. In the third group, hybridization with the K562 cell suppressed the membrane-Ig expression of the B-cell partner. Total cellular immunoglobulin determinations showed that some cells synthesized light chains in excess of heavy chains, others contained an excess of heavy chains, while still others had equal amounts of heavy and light chains. The hybrids showed a variety of patterns, including amplification of the parental phenotypes, appearance of new phenotypic combinations, and eclipse of one or both parental phenotypes. A comparison of the total and the membrane-associated immunoglobulin patterns suggests independent handling of intracellular and membrane immunoglobulin synthesis.

B-Lymphocytes↗
PubMed1981

The teaching of history-taking and diagnostic thinking: description of a method.

This paper describes the use of short videotaped doctor-patient history-taking encounters, which demonstrate the generated-hypothesis-verifying (GHV) method of enquiry. We urge that this method be taught formally to medical students, to complement the classical 'rigid' method of history taking.

Education, Medical, Undergraduate↗
PubMed1981

Deficiency of malic enzyme: a possible marker for malignancy in lymphoid cells.

Soluble malic enzyme (MEs) has been examined in long-term human lymphoid cell lines cultured from 101 individuals. In 65 out of 66 lines derived from people without lymphoreticular malignancy the enzyme was very active. Lines established from 35 individuals with various forms of lymphoreticular malignancy were also examined, including in some cases more than 1 line derived from the same patient. In all cases where the cell line was thought to be derived from normal cells MEs was active, but in 27 out of 29 lines thought to be derived from malignant cells (from 25 patients) MEs was not detected. In the case of two patients with chronic lymphatic leukaemia 'normal' lines active for malic enzyme, and 'leukaemic' lines lacking malic enzyme, had been cultured from the same individual. Preliminary investigations of the lack of malic enzyme in somatic cell hybrids derived from lymphoma and leukaemia cell lines are compatible with an alteration at the level of the structural locus MEs on chromosome 6. However, the restoration of MEs activity in one line by fusion with mouse teratocarcinoma cells suggests that the alteration may be of a regulatory nature.

Animals↗
PubMed1981

Decay of Moloney leukemia virus production after enucleation of chronically infected mouse cells.

The effect of enucleation of synthesis of Moloney leukemia virus was studied in chronically infected YACIR-A9 mouse hybrid cells. The synthesis of infectious virus decreased gradually until, 12 h after enucleation, virtually no infectious virus was produced. As determined by particle-bound p30 and reverse transcriptase, cytoplasts produced a low level of noninfectious viral particles. Thus, the assembly of virus particles does not appear to be wholly dependent on the presence of the cell nucleus. In contrast, production of infectious particles shows an absolute requirement for the cell nucleus.

Animals↗
PubMed1980

Restriction of C-type viral antigen in H-2/Fv-1 syngeneic mouse somatic cell hybrids.

Somatic cell hybrids between an AKR lymphoma or a C3H sarcoma and H-2, Fv-1 syngeneic CBA sarcoma or carcinoma have been examined for expression of the structural components of murine leukemia virus (MuLV) by radioimmunoassay and complement-dependent cytotoxicity assay. Parental AKR and C3H cells contained high concentrations of MuLV core protein p30 in their cell extracts and showed high sensitivity to anti-MuLVgp70 and p30 sera. In contrast, CBA cells expressed little detectable p30 in the extracts, were much less sensitive to anti-gp70 serum, and were almost insensitive to anti-p30 serum. The hybrids between the AKR or C3H cells and CBA cells had a decreased amount of p30 in the extracts and were almost resistant to cytotoxicity by anti-p30 serum, although they maintained high sensitivity to anti-gp70 serum. These findings suggest that the CBA genotype suppresses the production and cell-surface expression of p30 antigen of AKR and C3H endogenous C-type viruses. The suppressive gene is not Fv-1n.

Animals↗
PubMed1980

Hybridization of a myeloid leukemia-derived human cell line (K562) with a human Burkitt's lymphoma line (P3HR-1).

The myeloid leukemia-derived Epstein-Barr virus (EBV)-negative human lymphoid cell line K562 was successfully hybridized with the EBV-carrying Burkitt's lymphoma line P3HR-1. Authenticity of the hybrid PUTKO-1 was established by chromosome and isoenzyme studies. A virtually complete hybrid PUTKO-1 carried the EBV genome derived from the lymphoma parent. It averaged 26 EBV DNA copies per cell and was 100% positive for Epstein-Barr virus-associated nuclear antigen (EBNA). In most respects, the hybrid resembled the K562 parent: It had a high Fc receptor concentration, high sensitivity to natural killer cells, absence of EBV C3 receptors, and deficiency of membrane-associated beta 2-microglobulin (beta 2M) and HLA, in parallel with intracellular synthesis and secretion of beta 2M to the medium. Unlike the P3HR-1 parent, the hybrid was completely nonpermissive for antigens of the EBV cycle, early antigen, and viral capsid antigen. None of the 3 inducing agents, 5-lodo-2'-deoxyuridine, 12-O-tetradecanoyl-phorbol 13-acetate, or sodium butyrate, caused any viral antigen synthesis in PUTKO-1 in contrast to the good inducibility of the parental P3HR-1 subline. Thus the myeloid parent restricted expression of EBV antigens except EBNA. This exception further supports the concept that EBNA is an autonomous function of the viral genome, independent of host cell control that regulates expression of antigens related to the viral cycle. On the contrary, extinction of viral antigens in this hybrid between 2 cell lineages supports our previous concept that the ability to produce viral antigens is similar to a differentiated B-cell property.

Antigens, Surface↗
PubMed1978

Somatic cell hybrids between human lymphoma cell lines. V. IdUrd inducibility and P3HR-1 superinfectability of Daudi/HeLa (DAD) and Daudi/P3HR-1 (DIP-1) cell lines.

We have studied two types of somatic cell hybrid with regard to expression of the Epstein-Barr virus (EBV) cycle and its regulation. The first, DIP-1, a hybrid formed between two human lymphoma EBV producers (Daudi and P3HR-1), contained EBV DNA, expressed the virus-determined nuclear antigen (EBNA), andwas a producer of the EBV-associated antigens EA (early antigen) and VCA (viral capsid antigen). The second, DAD, a hybrid series of clones formed between Daudi and a HeLa cell derivative (D98), differed with regard to the expression of EBNA, EA, VCA and the content of EBV DNA. EA was regularly induced in the EBV DNA-containing hybrids following treatment with iododeoxyuridine (IdUrd). This induction was greater in lines spontaneously expressing EA. In two hybrids, DIP-1 and DAD10, VCA and virus DNA synthesis were also induced in the presence of IdUrd, the latter being detected by in situ hybridization with P3HR-1 EBV complementary RNA. Finally, while DIP-1 was superinfectable by the P3HR-1 EBV strain, the DAD series of hybrids were refractory to P3HR-1 superinfection and lacked EBV receptors.

Antigens, Viral↗