H. Francis Havas

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The influence of environmental (extracellular) pH on the sporulation rhythm in Neurospora crassa was investigated for wild-type (frq+) and the mutants chr, frq1, frq7, and frq8. In all mutants, including wild type, the growth rate was found to be influenced strongly by extracellular pH in the range 4-9. On the other hand, for the same pH range, the period(More)
This study focuses on the effect of varying regimens of cocaine administration on three parameters of the immune response: antibody production, resistance to infection by Streptococcus pneumoniae following immunization, and resistance to tumors. The effect of cocaine on antibody production of female and male BALB/c mice was investigated to both a(More)
that bacterial toxins from Serr&ia rnarc&wena and Streptococcus pyogenes are considerably less toxic when adminis tered to normal mice than when given to mice bearing Sarcoma 37 (1, @). A @0-to SO-fold dosage increase of the toxins is required to produce tissue changes and mortality rates in normal mice equiv alent to those produced in tumor-bearing(More)
Previously we had established that TEPC-183 IgM(K) suppressed the primary immune response (IR) to both the T-dependent antigens 2,4-dinitrophenyl-haemocyanin (DNP-HCY) and T-independent pneumococcal polysaccharides. In the current investigation, the effect of TEPC-183 on an ongoing immune response to SS-III and DNP-HCY was examined. It was found that when(More)
Mice bearing the immunosuppressive plasmacytoma TEPC-183 exhibit a marked splenic hyperplasia. We have characterized these tumor-reactive splenocytes on the basis of cell surface marker expression, nonspecific esterase activity, and morphology. Although splenocyte numbers increased progressively throughout tumor growth, B- and T-lymphocytes, as defined by(More)
The effect of tumor growth on serum immunoglobulin levels and on the immune response to sheep erythrocytes (SRBC) was studied in BALB/c mice bearing MOPC-315 (IgA), MOPC-460 (IgA), MOPC-173 (IgG2a) and MOPC-104E (IgM) to gain insight into the immunologic competence of the plasmacytoma-bearing host. The initial increase of myeloma protein coincided with the(More)
Mice bearing TEPC-183, an immunoglobulin M(kappa)-secreting plasmacytoma, exhibit severe suppression of their immune responses to both thymus-dependent and thymus-independent antigens, 2,4-dinitrophenyl, and the type 3 pneumococcal polysaccharide SSS-III. This immunosuppression is not lifted by splenectomy of the tumor-bearing mice or prevented by removal(More)
Mice bearing TEPC-183, an immunoglobulin (M(kappa)-secreting plasmacytoma, exhibit severe suppression of their immune responses. Since chemotherapy with cyclophosphamide (CY) is used in the treatment of myeloma, the present study was undertaken to determine its effect on the immune response. CY was tested at different doses in order to establish whether a(More)