PubMed Health⌕ Search

Biomedical subjects

A Yaniv

Publications and source records attributed to A Yaniv.

At least 73 records · Page 4Linked to original sources
PubMed1983

Blastogenic response of lymphocytes derived from patients with hematopoietic malignancies to antigens of a type C retrovirus isolated from a Burkitt's lymphoma cell line.

Cellular immune response to antigens associated with a type C retrovirus derived from Burkitt's lymphoma (BL) lymphoblastoid cells was studied in patients with hematopoietic malignancies, noncancer patients and healthy controls. Response was determined by lymphocyte blastogenesis assay measuring [3H]-thymidine incorporation, thereby enabling the calculation of stimulation indices (SI). Positive response (SI greater than 2.0) was demonstrated in patients with multiple myeloma (MM), chronic lymphocytic leukemia (CLL), chronic myelocytic leukemia (CML) and BL. No response was demonstrated in the non-cancer and healthy controls. Specific blastogenic response was obtained towards antigen extracted from three different cell lines infected with the tested type C retrovirus. No response was evident towards purified whole or purified disrupted virions or antigen extracted from murine myeloma MOPC-315 cells secreting a murine type C retrovirus or an antigen extracted from Mason-Pfizer monkey virus-infected NC-37 cells. The correlation between human hematopoietic malignancies and the in vitro lymphocyte blastogenic response to the BL-derived type C retrovirus was statistically highly significant.

Adult↗
PubMed1982

Organotropism of the lymphoproliferative disease virus (LPDV) of turkeys.

Turkey poults were inoculated with lymphoproliferative disease virus (LPDV) of turkey, and the organotropism of the inoculated virus was determined from the kinetics of virus expression and tumor formation. Molecular hybridization experiments, conducted to determine the level of viral RNA expression in the various organs of infected birds, established lymphoid tissues, including bone marrow, as the target for LPDV infection. Of these, bone marrow was the first to be infected but subsequently virus replication extended to the thymus, the spleen and the bursa Of Fabricius. The low level of LPDV expression in non-target organs probably stemmed from infiltration of infected lymphatic cells. The fact that the main organs for virus replication were not invariably the ones most clinically involved suggests that the target cells for virus infection need not necessarily be the targets for virus oncogenicity. A possible mode for LP[DV infection and transformation is proposed.

Animals↗
PubMed1982

DNA-processing activities associated with the purified alpha, beta 2, and alpha beta molecular forms of avian sarcoma virus RNA-dependent DNA polymerase.

The RNA-dependent DNA polymerase purified from B77 avian sarcoma virus exhibited two distinct DNA-processing activities. The alpha and beta 2 isoenzymes possessed an endodeoxyribonuclease activity capable of nicking simian virus 40 superhelical DNA, whereas the alpha beta isoenzyme performed as an untwisting topoisomerase. Both activities associated with the three molecular forms of the retroviral DNA polymerase were dependent on the presence of either Mn2+ or Mg2+ ions. From analysis of the denaturated DNA products, it is apparent that the alpha and beta 2 isoenzymes introduced two nicks, one per each strand in the superhelical simian virus 40 DNA molecules, whereas the alpha beta polymerase converted these supercoiled molecules to the relaxed covalently closed circular form. The notion that the DNA-processing activities are located on the DNA polymerase molecules was supported by the following: (i) the three isoenzymes were of a high purity; (ii) the activities cosedimented in glycerol gradients with the DNA polymerase activities of the alpha, beta 2, and alpha beta molecular forms; and (iii) immunoglobulin directed against the purified polymerase immunoprecipitated the DNA-processing activities. Chemical treatments of the DNA polymerase molecules (with pyridoxalphosphate, iodoacetamide, and sulfhydryl reagents), which inhibited the polymerase activity, also suppressed the endonucleolytic and topoisomerase activities, suggesting that cystein and amino groups play an important role in the active sites of the DNA-processing activities as well.

Alpharetrovirus↗
PubMed1981

Host range and oncogenicity studies of the murine myeloma MOPC-315 type-C retrovirus.

The biological features of an endogenous type-C RNA tumor virus released by the murine plasmacytoma MOPC-315 were determined. The virus was found to be pure ecotropic and, according to its capability to infect both NIH/3T3 and BALB/3T3 cells, it was established as an NB tropic virus. This tropism became more pronounced as a consequence of multiple passage in balb/3T3 cells. In view of the ability of myeloma viruses to efficiently infect BALB/c cells, their possible role in myeloma induction is considered.

Animals↗
PubMed1980

Evidence for type-C retrovirus production by Burkitt's lymphoma-derived cell line.

Burkitt's lymphoma cell line, P3HR-I, was found to secrete virions with properties of known type-C RNA tumor viruses. The viral particles had a buoyant density of 1.16 g/ml in sucrose gradients and contained a high-molecular-weight RNA and an RNA-instructed DNA polymerase. The viral polymerase was active in an endogenous reaction requiring the presence of the four deoxyriboside triphosphates and manganese ions, and was sensitive to RNase. The DNA product of the endogenous reaction specifically hybridized to P3HR-I viral 60 to 70S RNA. Electron microscopic examination of ultrathin sections of P3HR-I cells revealed immature, mature and budding virions typical of type-C retroviridae. Nucleic acid hybridization assays showed no sequence homoblastosis virus, murine oncornaviruses, simian sarcoma virus or RD114 virus.

Burkitt Lymphoma↗
PubMed1980

RNA-dependent DNA polymerase of an endogenous type C virus of mice: purification and partial characterization.

An RNA-dependent DNA polymerase was isolated from purified virions of endogenous oncornaviruses released by the MOPC-315 murine myeloma cell line. Upon sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the purified enzyme was found to consist of two major polypeptides with molecular weights of about 28,000 and 26,500. The active enzyme had a molecular weight of approximately 56,000, as calculated from its sedimentation on glycerol density gradients, indicating that it is probably a dimer of the two subunit polypeptides. The isolated MOPC-315 virus polymerase exhibited all three activities known to be found in the DNA polymerase from oncornaviruses, namely, an RNA-dependent DNA polymerase, a DNA-dependent DNA polymerase, and an RNase H. The RNA-dependent polymerase activity showed a prounced preference for Mn2+ over Mg2+, whereas the DNA-dependent and RNase H reactions were catalyzed by these two cations to an almost equal extent. The purified polymerase was found to be immunologically related to the polymerase of Rauscher murine leukemia virus.

Animals↗
PubMed1979

Type C virus and immunoglobulin A production by murine myeloma MOPC-315: two independent activities.

The suspected correlation between cessation of type C virus production and halt in immunoglobulin secretion by murine myeloma cells was studied. Employing two variants of the murine myeloma MOPC-315, immunoglobulin A-producing and nonproducing cells, we demonstrated that the two myelomas release similar levels of type C viruses which share common nucleotide sequences and that the viral genomes are equally expressed within the cells. Thus, the suggested relation between these two activities does not apply for MOPC-315 cells and probably for other murine myelomas also.

Animals↗
PubMed1979

Biochemical characterization of the type C retrovirus associated with lymphoproliferative disease of turkeys.

Turkeys inoculated with spleen extracts from lymphoproliferative disease (LPD)-affected birds developed viremia, followed by typical LPD lesions. Electron microscopy and biochemical characterization established that the virus present in the blood of infected turkeys is a type C retrovirus. The viral particles possess a buoyant density of 1.17 g/ml in sucrose gradients; they contain high-molecular-weight RNA and an RNA-instructed DNA polymerase with efficient exogenous and endogenous activity. The LPD virus polymerase is preferentially activated by magnesium ions. Cross nucleic acid hybridization assays revealed no sequence homology between the viral genome of LPD and avian myeloblastosis virus or reticuloendotheliosis virus, thus indicating that the LPD virus belongs to a distinct group unrelated to the avian leukosis-sarcoma virus complex or to the reticuloendotheliosis virus group.

Animals↗
PubMed1979

Molecular evidence for a type C retrovirus etiology of the lymphoproliferative disease of turkeys.

Recently, we isolated from the blood of lymphoproliferative disease (LPD)-affected turkeys a type C retrovirus distinct from the avian leukosis-sarcoma virus complex and the reticuloendotheliosis virus group. We present molecular evidence for the implication of this virus in the LPD of turkeys. Using complementary DNA of LPD viral RNA, we found that the LPD viral genome is specifically and efficiently transcribed (2,500 copies per cell) in LPD tumor cells. Moreover, the LPD tumor cells contained newly inserted LPD viral information (5 to 10 copies per haploid genome), which was not present before the infection. From the absence of LPD virus-specific sequences in the normal cell genome of turkeys, it was concluded that the LPD virus is not an endogenous virus of turkeys. DNA-DNA annealing experiments revealed that the degree of sequence homology between LPD viral complementary DNA and cellular DNA of turkeys was not higher than that between LPD viral complementary DNA and cellular DNA of other species, thus indicating that the virus does not originate from turkeys.

Animals↗
PubMed1979

Morphologic characterization of proliferative cells and virus particles in turkeys with lymphoproliferative disease.

The tumors found in turkeys having lymphoproliferative disease (LPD) are histologically characterized by a pleomorphic population of cells of the lymphoid series. Electron microscopy has shown that, despite marked differences in shape and size, the proliferating cells share basic ultrastructural features, indicating their lymphoid origin. Virus particles morphologically and morphogenetically characteristic of type C oncorna-viruses of Retraviridae were found in different organs and plasma samples of diseased or infected turkeys with LPD. This LPD type C virus resembled members of the reticuloendotheliosis virus group but not members of the avian sarcoma virus group.

Animals↗
PubMed1978

Locality principle in wave mechanics.

This paper proves a locality principle for a wave-mechanical particle governed by the Schrödinger equation. It is shown that rho(r,beta), the Laplace transform of the local density of states n(r,E), depends significantly only on the potential V(r') at points r' near r. The effect of changes of V(r') at distant points r' (|x(i)' - x(i)| > a) on rho(r,beta) decay in a Gaussian fashion with a. This result sheds some light on the locality of physical properties of extended systems and provides general support for various local methods of calculation.

Journal Article↗
PubMed1978

Chicken egg yolk stabilizes the reverse transcriptase activity in type C particles produced by cultured MOPC-315 murine myeloma cells.

Type C particles released from cultured murine myeloma MOPC-315 cells were significantly protected when the purification steps were all conducted in the presence of 10% chicken egg yolk fluid. The yolk fluid also slowed down the inactivation of viral particles during incubation at 37 degrees C and enabled full recovery of viral particles through several cycles of freezing and thawing. The purification of viral particles in the presence of yolk fluid did not affect the capability of the viral DNA polymerase to reverse-transcribe the virion RNA in vitro, nor that of the viral RNA to act as a functional template.

Animals↗
PubMed1978

Establishment and characterization of a cell line derived from human colon adenocarcinoma (HuCCL-14).

A continuous human colon carcinoma cell line (HuCCL-14) was established whose cells possess an epithelial-like morphology and are capable of growing in soft agar and on monolayers of normal cells. HuCCL-14 cells yielded high levels of carcinoembryonic antigen, and the analysis of their chromosomal constitution revealed a mode of 70 chromosomes per cell. HuCCL-14 cells produce malignant tumors when injected into nude mice. Preliminary virologic studies indicate the release of RNA particles having a density of 1.15--1.19 g/ml.

Adenocarcinoma↗