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The -30,000 dalton woolly and gibbon type-C viral

The immunobiology of heterotransplanted human tumors was investigated following transplantation into nude mice of human bronchogenic, colon, rectal, ovarian, gastric, endometrial, vaginal, bladder, renal, esophageal, embryonic cell, pancreatic, and breast carcinoma, as well as fibrosarcoma, rhabdomyosarcoma, malignant melanoma, astrocytoma, Wilm's tumor, endometrial hyperplasia, and hydatidiform mole. Several of these tumors were passaged up to 15 generations. During these passages no changes in latency period for tumor development or in histology were noted. There were significant differences between several tumors in the minimum number of cells required for successful transplantation; such differences were independent of the basic biologic aggressiveness of the individual tumors. Nude mice that received transplants of fibrosarcoma and endometrial carcinoma had increased serum IgM and numbers of spleen cells and complement receptor lymphocytes. No such changes were noted for mice that received transplants of malignant melanoma, In contrast, there were no apparent differences in the responses of nude mice, who were given transplants of human tumors, to be T-cell mitogens concanavalin A or phytohemagglutinin or in the number of theta-bearing spleen cells. The success rate for transplantation was significantly improved when explants, rather than single-cell suspensions, were performed. Tumors transplanted to nude mice derived from strictly homozygous matings behaved like tumors transplanted to mice born of heterozygous mothers. Finally, despite the dramatic size of subcutaneous tumor nodules, there were no examples of invasion or distant metastases.

Young gibbons that were experimentally inoculated with cell-free gibbon ape leukemia virus (GaLV) and developed peristent viremia subsequently developed chronic granulocytic leukemia (CGL) with associated multifocal bone lesions and metastases. An 8-month-old gibbon inoculated with 10(5) tissue culture infectious virus (TCIV) developed acute myeloproliferative disease with associated bone lesions after a latency of 5 months, while a 9-month-old gibbon inoculated with 10(3) TCIV developed CGL after and 11-month latency. The clinical symptoms associated with the onset of leukemia were an increased number of leukocytes which were predominantly mature granulocytes, development of anemia, and multifocal bone lesions. Terminally, the animals had elevated immature granulocytes in the blood, cellular bone marrow with a predominant number of immature granulocytes, and hepatosplenomegaly. The gibbon with CGL had metastatic growth in the spleen and lung. Two 14-month-old gibbons that were inoculated with 10(3) TCIV and developed persistent neutralizing antibody to the virus infection remained free of hematopoietic disease, as did uninoculated animals. The fact that only animals with persistent viremia developed leukemia supports the oncogenicity of GaLV in gibbons.

Hybridization studies employing single-stranded 3 H-DNA transcripts of type-C viruses isolated from a woolly monkey or gibbon ape failed to detect nucleic acid sequences homologous to these viruses in the DNA from a variety of uninfected primate species. The possible significance of these results for the epidemiology of type-C viruses in primates is discussed.

Familial hyperproinsulinemia is characterized by the accumulation of proinsulin-like material (PLM) in the plasma of affected patients. This disorder is inherited in an autosomal dominant fashion. The accumulation of PLM is thought to be due to the impaired conversion of proinsulin to insulin. Although PLM has been suggested to have an amino acid substitution, it has been impossible to locate and identify a substituted amino acid, due to the difficulty in isolating sufficient amounts of PLM from plasma samples.Therefore, we analyzed leukocyte DNA from one member of a proinsulinemic family, and we found a point mutation that changed guanine to adenine in the insulin gene. This transition implies that a substitution of histidine for arginine has occurred at amino acid position 65. Furthermore, it indicates that arginine at 65 is essential for the conversion of proinsulin to insulin. Our results suggest a novel mechanism by which disease can be incurred: a heritable disorder can result from a posttranslational processing abnormality caused by a point mutation.

Linear sucrose-density gradient was used to detect and isolate typical "C"-type viral particles in plasma of cats with spontaneous and experimentally induced leukemia. The density of the agent is similar to known murine leukemia virus (1.15 to 1.17 grams per cubic centimeter). In the electron microscope the virus showed typical "C"-type particle morphology with various maturation stages. The maximum diameter of the mature viral particles in plasma was 115 millimicrons, a diameter slightly larger than budding particles observed in tissue. Leukemia was transmitted with cellular and cell-free inoculum after a 5-week period of latency.