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Biomedical subjects

A Peled

Publications and source records attributed to A Peled.

86 records · Page 5Linked to original sources
PubMed1977

Immunologic characteristics in relation to high and low leukemogenic activity of radiation leukemia virus variants. I. Cellular analysis of immunosuppression.

Infection of adult C57BL/6 mice with variants of the radiation leukemia virus resulted in variable leukemia incidence. One variant, designated D-RadLV, induced lymphatic leukemia in 0 to 25% of mice after virus inoculation directly into the thymus of young adult mice. The leukemia incidence could be increased to 80 to 100% by host exposure to x-rays. The second variant, A-RadLV, induced lymphatic leukemia in 80 to 100% of similarly inoculated mice without the need for additional radiation treatment. Adult mice were inoculated with D-radLV or A-RadLV. Both variants reduced the immune response to sheep erythrocytes whereas only D-RadLV had an immunosuppressive effect after immunization with a thymus-independent immunogen polyvinyl-pyrrolidone (PVP). Results of transfer experiments indicated that the immunosuppressive effects were expressed at the immunocompetent cell level. Thymus-derived cells were affected by A-RadLV since their immunocompetent function was impaired, whereas D-RadLV affected the marrow cell population of immunocytes. Exposure of D-RadLV-inoculated mice to x-rays induced functional impairment of both thymus and marrow cells. Since the radiation leukemia virus induces "T" lymphatic leukemia it could be proposed that the initial tropism of the virus to thymocytes would lead to high leukemia induction potential, whereas virus tropism to bone marrow cells would yield a low leukemia incidence. The coleukemogenic effect of x-rays could perhaps be related with its capacity to alter and introduce a change in virus-lymphoid cells interaction.

Animals↗
PubMed1975

Pathways in thymus- and bone marrow-derived lymphatic leukemia in mice.

The radiation- and radiation leukemia virus-induced leukemias in C57BL/6 strain mice were found to be of the thymus-derived (T) lymphocyte origin. Experimental evidence indicated that the interaction of the radiation leukemia virus with thymus-derived lymphoid cells and specifically with the thymus subpopulation bearing high levels of H-2 alloantigens were prerequisites for the development of high leukemia incidence in these test systems. In radiation leukemogenesis in C57BL/6 mice it was shown that within several days following the radiation treatment a "released" leukemogenic agent was found in the irradiated bone marrow; whereas, several days following chemical carcinogen leukemogenesis in SJL/J mice, established preleukemic or leukemic cells could be detected in the bone marrow. The analysis concerned with the lymphoid origin of chemical carcinogen-induced lymphatic leukemias in SJL/J mice indicated clearly that the carcinogen could affect different lymphoid populations. The majority of the chemical-induced leukemias were of the bone marrow-derived (B) lymphocyte origin, although some leukemias were of T lymphocyte origin, and some tumors could not be classified as either T or B leukemias, perhaps representing stem cells which do not carry the characteristic surface antigens for mature T and B cells.

9,10-Dimethyl-1,2-benzanthracene↗
PubMedDate not supplied

The perception of rorschach inkblots in schizophrenia: a neural network model.

Schizophrenia is a psychiatric disorder characterized by a variety of cognitive deficits, including perceptual distortions and hallucinations. In recent years several studies have proposed that schizophrenia may involve a disturbance of "context". We have used a three layer neural network model constructed from an input layer followed by two computational layers to simulate responses of schizophrenic patients to the Rorschach test. In this test subjects respond to a set of ambiguous patterns created by ink blots on paper. Our model proposes that a disturbance of context caused by altered noise-to-signal ratio at the level of the single units, is responsible for schizophrenic responses to the Rorschach test. The assumption that catecholaminergic neurotransmitter systems regulate noise-to-signal ratio in cortical neurons constitutes a link between findings of altered neurotransmitter activity and deficits of cognitive functions requiring contextual integration in schizophrenia. The development of models for specific task deficits in schizophrenia could advance our insights regarding the neurological mechanisms underlying serious mental disorders such as schizophrenia.

Humans↗