Biomedical subjects

R Teller

Publications and source records attributed to R Teller.

4 recordsLinked to original sources

PubMed1998

Genes in the pX region of human T cell leukemia virus I influence Vav phosphorylation in T cells.

Human T cell leukemia virus I (HTLV-I) causes acute leukemic disease in a low percentage of infected individuals through obscure mechanisms. Our studies compare two rabbit HTLV-I-infected T cell lines: one, RH/K34, causes lethal experimental leukemia and the other, RH/K30, mediates asymptomatic infection. We show herein that the product of the protooncogene vav is constitutively Tyr-phosphorylated in RH/K34 but not in RH/K30. A role for the retrovirus in phosphorylation of Vav was assigned by transfection experiments with molecular clones of HTLV-I derived from the two lines. The HTLV-I molecular clone from RH/K30, but not that from RH/K34, down-regulates Vav phosphorylation in a Herpesvirus ateles-transformed T cell line. Use of recombinant virus clones revealed that a pX region sequence differing by two nucleotides between the two clones mediates this down-regulation. Because Vav is involved in T cell signaling and Vav phosphorylation occurs upon activation of T cells, control of the activation state of Vav by viral proteins may relate to the leukemogenic potential of certain HTLV-I-infected cells.

Animals↗

PubMed1995

HIV-1 mediates rapid apoptosis of lymphocytes from human CD4 transgenic but not normal rabbits.

Normal rabbit lymphocytes can be infected with HIV-1 although infection is much less efficient than in human lymphocytes. When peripheral blood mononuclear cells (PBMC) from rabbits transgenic for human CD4 (HuCD4) were exposed to HIV-1, enhanced infection and a rapid depletion of lymphocytes were observed. Cell death in the infected cultures occurred via apoptosis, but no similar effect was seen in nontransgenic rabbit PBMC cultures. Induction of apoptosis in HuCD4-expressing cells required virus replication; heat-inactivated virus or recombinant viral proteins had no effect on cell viability. Expression of the Fas antigen was increased in HIV-1-infected CD4+ rabbit lymphocytes. Characterization of the infected PBMC cultures revealed that apoptosis occurs both in HuCD4+ and HuCD4- cells, indicating that bystander cells are killed. These data define a requirement for HuCD4 in initiation, but not the spread, of HIV-1-induced apoptosis in rabbit PBMC and provide a model to probe mechanisms leading to lymphocyte depletion in HIV-1 infection.

Animals↗

PubMed1995

Rabbits transfused with human immunodeficiency virus type 1-infected blood develop immune deficiency with CD4+ lymphocytopenia in the absence of clear evidence for HIV type 1 infection.

Rabbits can be infected with human immunodeficiency virus (HIV-1), but no disease signs similar to acquired immunodeficiency syndrome (AIDS) have been reported to date. In our attempt to develop types of HIV-1 more virulent for rabbits, an immunodeficiency characterized by CD4+ lymphocytopenia and opportunistic infection was induced by transfusion from HIV-1-infected rabbits. The original donor was infected for 27 months; initial passage resulted in infection of two rabbits. Transfusions from these two infected rabbits. Transfusions from these two infected rabbits caused immunodeficiency in 12 recipients. One rabbit died at 3 months and a second at 8 months postransfusion with lymphocyte depletion in lymphoid organs; one of these and another of the CD4+ lymphocytopenic rabbits had opportunistic infections. Lentivirus-like particles were detected in thymus and spleen from an affected rabbit. Despite appearance of AIDS-like disease signs, antibodies to HIV-1 probes were detected in rabbits receiving passaged blood. However, RNA transcripts hybridizing with HIV-1 probes were detected in organs of some rabbits, implicating the initial HIV infection in the disease. Transfusion from uninfected donors produced no signs of immunodeficiency, which suggests the involvement of an HIV-related agent. The present data do not allow definitive characterization of the agent(s) involved in the immunodeficiency. Possibilities include activation of a rabbit retrovirus or, alternatively, development of a mutated HIV-1 strain.

Animals↗

PubMed1989

Downsizing.

With a clear idea of the goals of downsizing, a planning process which ensures the participation of as many as possible, on-going and effective communication systems, and concrete strategies for living with the results, both employee morale and customer service can be improved in spite of the necessity of "doing more with less."

Communication↗