Oncogenic transformation of hamster embryo cells after exposure to inactivated herpes simplex virus type 1

The in vitro transformation of hamster embryo fibroblasts by herpes simplex virus type 1 (HSV-1) after exposure of the virus to UV irradiation is described. Cell transformation was induced by 2 out of 12 strains of HSV-1 that were tested for transforming potential. Cells transformed by the KOS strain of HSV-1 were not oncogenic when injected into newborn Syrian hamsters. However, cells transformed by HSV-1 strain 14-012 induced tumors in 47% of the newborn hamsters injected. HSV-specific antigens were found in the cytoplasm of cells transformed by both virus strains. Sera from tumor-bearing hamsters contained HSV-1- and HSV-2-neutralizing antibodies as well as antibodies which reacted specifically with HSV antigens by the indirect immunofluorescence technique. Hamster oncornavirus antigens were not detected by immunofluorescence methods. These observations represent the first evidence of the oncogenic potential of HSV-1.

Immunoelectrophoretic analysis of avian ribonucleic acid tumor virus group-specific antigens

Tumors induced in pigeons by inoculation with the Schmidt-Ruppin strain of Rous sarcoma virus regressed after about 6 weeks. Sera from these pigeons, taken 8 weeks after inoculation, had complement-fixing group-specific antibody titers of 1:2 to 1:256. In immunoelectrophoresis with the pigeon serum, disrupted BAI strain A (myeloblastosis) avian tumor virus showed at least five precipitin arcs. The pattern of precipitin lines was dependent in part on the means used for virus disruption, and ethyl ether and nonionic detergents appeared to be both effective and relatively mild reagents. Immunoelectrophoretic comparison of pigeon serum with serum from a tumor-bearing hamster and that from virus-inoculated rabbits yielded similar, though not identical, results.

Serum iron and iron-binding capacity in normal and tumour-bearing golden hamsters

In contrast to other plasma constituents, serum iron levels in hamsters were notably different (higher) from those in man. There were no significant differences in serum iron levels or iron-binding capacity between tumour-bearing and normal hamsters, or between the sexes.

Properties of hamster embryo fibroblasts transformed in vitro after exposure to ultraviolet-irradiated herpes simplex virus type 2

An in vitro method which led to the transformation of hamster embryo fibroblasts after exposure to herpes simplex virus type 2 (HSV-2) inactivated with ultraviolet irradiation is described. The transformed cells (333-8-9) produced tumors when inoculated into newborn Syrian hamsters but not when injected into weanling Syrian hamsters of the same LSH inbred strain. However, after one in vivo passage, the 333-8-9 cells became highly oncogenic in weanling hamsters. No infectious virus was recovered from these cells. Herpes simplex virus antigens were detected in the transformed cells by the indirect immunofluorescence technique. Sera from tumor-bearing hamsters contained antibody with highly specific neutralizing activity against HSV-2. These studies indicate the continued involvement of the HSV-2 genome in an oncogenic cell line.

Proinsulin-like component of circulating insulin in the basal state and in patients and hamsters with islet cell tumors

The proinsulin-like component comprised approximately 20% of total circulating basal immunoreactive insulin in 15 patients without islet cell tumors. 15 min after oral glucose, the concentration of the proinsulin-like component was unchanged and its percentage of the total immunoreactive insulin decreased with the acute release of the insulin component. By 2 hr after oral glucose, the concentration of the proinsulin-like component increased and the insulin component concentration decreased so that the percentage of the proinsulin-like component was essentially the same as in the basal state. In five patients with islet cell tumors and fasting hypoglycemia, basal proinsulin-like component ranged from 26 to 79% of the total immunoreactive insulin. While basal proinsulin-like component was higher in the islet cell tumor patients, the fluctuations after stimulation were qualitatively similar to the nontumor patients. Acute stimulation with glucose, tolbutamide, leucine, and streptozotocin mainly released the insulin component resulting in a fall in the per cent proinsulin-like component with a subsequent increase in percentage of this component as the total insulin concentration returns towards basal levels. Three islet-cell tumor patients with less than 46% proinsulin-like component had favorable therapeutic responses to diazoxide whereas one patient with over 80% proinsulin-like component was completely refractory. Syrian hamsters bearing islet cell tumors provided an excellent model for islet cell tumors in man. These animals have a high proportion of a proinsulin-like component in plasma; stimulation of tumor slices in vitro with tolbutamide and glucagon releases mainly the insulin component similar to the observations in man. These studies suggest that the mechanisms regulating the release of the proinsulin-like and of the insulin components are different.

Purification and properties of L-asparaginase from Serratia marcescens

The purification and properties of a tumor inhibitory l-asparaginase from Serratia marcescens are described. The following properties of the enzyme were examined: kinetics of the enzyme reaction, catalytic activity as a function of pH, boundary sedimentation velocity, electrophoresis on polyacrylamide gel, immuno-electrophoresis against homologous and heterologous antisera, immunodiffusion, blood clearance rate in mice, and inhibition of the 6C3HED lymphoma in C3H mice. Complete regression of this tumor was obtained with a smaller dose of the enzyme from S. marcescens than with enzyme from Escherichia coli. The reason for this difference was not evident from a comparison of several properties of the two enzymes.

Hypoglycaemia and malignancy differences of closely related sublines of a rat tumour

A possible basis for the differences in malignancy between three closely related sublines of the WBP1 ascites tumour of the rat has been studied by examining the biochemical changes in rat sera during tumour growth in vivo. Death appeared to be due to hypoglycaemia and the ability to induce this condition correlated with the differences in malignancy between the sublines; WBP1 (X) and WBP1 (V), the more malignant sublines, inducing hypoglycaemia earlier and more rapidly than the least malignant subline WBP1 (A). Possible mechanisms whereby the tumour produces these effects are discussed.

Studies on nondefective adenovirus-simian virus 40 hybrid viruses. I. A newly characterized simian virus 40 antigen induced by the Ad2+ND 1 virus

The nondefective adenovirus 2 (Ad2)-simian virus 40 (SV40) hybrid virus, Ad2(+)ND(1), does not induce heat-labile SV40 T antigen but does induce a previously uncharacterized heat-stable SV40 antigen-the SV40 "U" antigen. This antigen is detectable by both immunofluorescence and complement fixation by using sera from hamsters with SV40 tumors. Sera from hamsters bearing SV40 tumors can be divided into two groups, those that react with both SV40 T and U antigens (T(+)U(+) sera) and those that react with SV40 T antigen only (T(+)U(-) sera). SV40 U-specific sera from monkeys immunized with Ad2(+)ND(1)-infected cells do not react with SV40 T antigen by immunofluorescence but do react with an antigen in the nucleus of SV40-transformed cells and with an early, cytosine arabinoside-resistant antigen present in the nucleus of SV40-infected cells. A heat-stable SV40 antigen detectable by complement fixation with T(+)U(+) hamster sera is present in extracts of SV40-induced hamster tumors and in cell packs of SV40-infected or -transformed cells. SV40 U-antigen synthesis by Ad2(+)ND(1) virus is partially sensitive to inhibitors of deoxyribonucleic acid synthesis, whereas U-antigen synthesis by SV40 virus is an early cytosine arabinoside-resistant event. As an early SV40 antigen differing from SV40 T antigen, U antigen may play a role in malignant transformation mediated by SV40.

The serum paraprotein level related to the number of plasmacytoma-5536 cells in C3H mice

An ascitic form of plasmacytoma (MP-5563) in C3H mice has proved stable on transplantation. A simple linear relationship was demonstrated between the serum level of the paraprotein produced and the total number of plasmacytoma cells within the ascitic fluid.