Peyton Rous

Carcinomatous Changes in Virus-induced Papillomas of the Skin of the Rabbit

The Shope rabbit papilloma, a skin growth caused by a virus, 1 has been shown to possess the characters whereby tumors are recognized. 2 When given opportunity, as on implantation within the host, the growth frequently looks and behaves like a malignant neoplasm. The present report is concerned with instances in which skin papillomas caused by the virus have spontaneously become carcinomatous. The change has been noted in 5 of 10 domestic rabbits with growths existing 4 to 8 months. During the early weeks of its development after virus inoculation the papilloma enlarges laterally, but later it is restricted by scar tissue and builds outwards only. At first it overlies the skin appendages, but these disappear after a time and it becomes bedded somewhat more deeply. The malignant change may first attract attention when a fissure exuding serosanguineous fluid opens in the midst of the papilloma; but more often there occurs a generalized, fleshy, discoid thickening of the base of the growth, which gradually raises the jagged, dry, papillomatous tissue some millimeters above the skin surface, and also bulges downwards. Soon the animal gnaws at this portion of the growth, opening in the one case a depressed ulceration with firm, gristly walls, and in the other laying bare a high, fungoid mass. On biopsy a squamous cell carcinoma is found, or an invasive, papillomatous, epithelial tumor, or most frequently, the 2 intermixed, with every gradation between them. The growth may for some weeks remain circumscribed and fungating, or it may rapidly extend under the skin, involving it and the muscle and becoming fixed upon the deep tissues. Some cancers less than 2 months old are already 5 cm. across and 2–3 cm. deep. As a rule they become infected with pus-producing organisms and the health of the host suffers, though most of our rabbits are still alive. Metastasis to a regional lymph-node (confirmed by section) has occurred once. Transplantation to the leg muscle of the host has resulted in a secondary, highly invasive, squamous cell carcinoma.

A Virus Causing Oral Papillomatosis in Rabbits

Summary Oral papillomatosis is common in domestic rabbits bred in the New York area. The disease is due to an hitherto undescribed virus which is evidently pathogenic for the oral mucous membrane only.

Tissue Affinity of Shope Papilloma Virus

Summary It is plain that the Shope papilloma virus is remarkably specific in its action, affecting only the epidermis of rabbits and hares and failing to influence embryonic epidermis or other kinds of epithelium, even when this is keratinizing as the result of avitaminosis A, or proliferating in consequence of Scharlach R stimulation.

The rate of tumor growth in underfed hosts

Workers with transmissible neoplasms have had frequent occasion to observe that sick or emaciated animals are relatively resistant as hosts for implanted tumor. It does not develop in them with the same readiness as in healthy individuals. A kindred phenomenon has been noted by Moreschi 1 in studying the relation of nutrition to tumor growth. He found that in mice losing weight on a low diet an engrafted sarcoma survived with less frequency and grew more slowly than in the well-fed controls. Indeed these controls died of their tumor sooner than did the fasting animals. This being so might it not be possible to delay by food-restriction the course of inoperable tumors? And might not the development of metastasis after excision of a primary growth be hindered by the same means? In an attempt to answer these questions the author has performed a series of experiments with the Flexner-Jobling adeno-carcinoma of the rat. This neoplasm in its invasive spread and tendency to metastasize has a striking likeness to some of the cancers of human beings. A bread compounded of oatmeal, rye-flour, corn-meal, milk and sugar, was baked in large quantity, dried, ground, and, with sufficient milk to moisten it, was used as the sole food of the experiment animals. Preliminary observations were made on several series of healthy rats to determine how little of the bread would sustain life while permitting of a gradual emaciation, and then I 10 young, growing animals, carrying the Flexner-Jobling tumor, were submitted, half to food restriction, while the other half were fed full and used as controls. The food was carefully measured out, the exact size of the tumors charted each week, and the rats weighed twice a week.

Parabiosis as a test for circulating antibodies in cancer

Sauerbruch and Heyde have united animals side by side, with an opening between the peritoneal cavities and suture of the apposed skin and connective tissue. They find that healing between two individuals thus joined brings with it a considerable physiological intimacy. Ranzi and Ehrlich, following them, have demonstrated that circulating antibodies pass with ease from one of such a pair to the other. On this evidence it seems possible to utilize the condition (parabiosis) for experiments on the question of the existence or non-existence of circulating antibodies for cancer. Accordingly, I have united white rats with a growing tumor, the result of transplantation, to others which had proved themselves resistant to the same type of neoplasm. Careful watch was kept for signs of retarded development or retrogression in the tumors thus brought under the continued influence of blood from a resistant animal, but no alteration of the sort was observed. The growths extended with the same rapidity as those in control animals. The findings are against the presence in circulation of destructive antibodies for cancer.

Karl Landsteiner, 1868-1943

Landsteiner was born in Vienna on 14 June 1868, of Jewish parents. His father Leopold, a journalist, died when the boy was six and he grew up the devoted companion of his mother, Fanny Hess Landsteiner, with whom he led so retired a life that the companions of his young manhood cannot recall even having seen her. She ruled through solicitude. Together they joined the Roman Catholic church when he was a stripling, and a Catholic he declared himself to be in a public statement made almost fifty years later. The announcement of his marriage was deferred until his mother had died and her death mask hung on the wall of his bedroom until his own life ended.

Effect of the Papilloma Virus (Shope) Upon the Tar Warts of Rabbits

When the papilloma virus is injected into the blood stream of rabbits previously tarred on the ears for 1 1/2 to 3 months, growths rapidly arise on the tarred skin, often in great numbers. Some are squamous cell carcinomas, 1 usually multiple, and frequently metas-tasing.∗ We have studied the phenomenon in more than 70 rabbits, with 90 tarred controls. In none of the latter has a cancer developed. Many of the growths that follow upon injection of the virus appear where no localized proliferation was previously visible, but others derive from pre-existing tar warts, which start growing rapidly, alter in aspect, and not infrequently manifest malignancy. After tarring is stopped, most ordinary tar warts disappear and the others become indolent, whereas the virus-stimulated warts keep on enlarging. Some are now carcinomatous but may undergo conversion into characteristic virus papillomas, as a scrutiny of several hundred specimens has shown; and others have become hybrids, neither ordinary tar tumors nor ordinary virus tumors but peculiar papillomas of malignant appearance, which change to squamous cell carcinomas almost at once. Not a few of the warts, however, though greatly stimulated by the virus (as proven by weekly records of their size), retain the morphology of the tar tumors. To learn more, opportunity was provided for the virus to infect tar warts in vitro. The warty tissue was punched from the ears, a slice taken for section, and equal portions of the hashed remainder were steeped for some minutes in Tyrode, and in a Berkefeld filtrate of Tyrode containing potent virus, respectively; after which they were implanted at corresponding situations in the leg muscles and subcutaneous tissue of the hosts. Four or 5 wart materials from each rabbit were so treated, as was also some of the tarred skin devoid of warting. Tarring was kept up during a few later days because of its presumptive general influence to favor proliferation. The warts utilized proved to be the familiar tar papillomas and car-cinoids, 2 so called because, though having the histology of carcinomas, and often ulcerating and growing through the ear, they ultimately disappear or revert to the benign, papillomatous form, even though tarring is continued. One implanted animal died 20 days later and 9 were killed after 38 to 64 days. None of the 44 wart materials steeped in Tyrode had given rise to a growth, nor had the skin specimens done so. Tiny cysts lined with ordinary, stratified squamous epithelium resulted from 5 of the former and from 4 of the latter, the others undergoing resorption. Ferrero 3 has reported similar findings. Very different was the outcome with the tissues steeped in virus. Then the bits of skin regularly gave rise to nodules of papillomatous tissue such as form on direct implantation of the Shope papilloma. 2 Similar nodules resulted from the implantation of 15 of the 24 tar papillomas, 4 yielded nothing, and 3 gave rise to small cysts like those just described. From one of the remaining 2 a malignant papilloma arose, markedly different from the original wart, and from the other a multicentric growth retaining the distinctive morphology of the latter. Nodules of Shope papillomatosis resulted from 8 of the 20 virus-steeped carcinoids, while 9 yielded nothing. In the remaining 3 instances, growths of carcinomatous aspect developed. The morphological characteristics of the original carcinoid had been retained in 2 of these cases, and the growths, though invasive, were small. The third was large, anaplastic and notably aggressive, to all appearances a malignant cancer, with but slight resemblance to the original carcinoid and none to those Shope papillomas that invade the muscle in which they are implanted. 4 The warts from which the implantation growths of cancerous aspect derived had been large at biopsy in 4 of the 5 cases, and much of their tissue had been left in situ. After tarring was stopped one of them continued to enlarge slowly, but became a benign papilloma histologically, while the other 3 disappeared. The biggest to disappear was 2.3 cm. across and had extended through the ear when about one-tenth of it was taken for steeping. The bits steeped in Tyrode yielded no growth, whereas those exposed to virus gave rise to the large, malignant tumor just mentioned. It is common knowledge that extraneous viruses 5 can flourish in tumors. Some induce no evident change, while others cause necrosis or the formation of inclusion bodies. The papilloma virus causes no inclusions, but it stimulates tar tumors to active growth, brings about morphological alterations in many of them, frequently acts as the determining factor in their survival, and makes some take on forthwith the character of carcinomas.

The Fixation of Certain Viruses on the Cells of Susceptible Animals and Protection Afforded by Such Cells

Rabbit embryo tissue was grown in a thin plasma clot and after some days the cultures were submitted to a trypsin solution strong enough to digest the clot and free the cells that had extended into it. 1 By repeated pipettings and filtrations through lens paper, alternated with differential washings in gelatin-Tyrode solution, suspensions were obtained of the living cells as individuals. They were mixed at room temperature with suspensions of virus, and after an interval the cells were recovered with the centrifuge, again washed repeatedly, treated in various ways and inoculated into rabbits. The viruses used were vaccinia and the filterable agent causing the rabbit fibroma described by Shope. 2 Cells exposed to virus and repeatedly washed invariably gave rise to lesions in susceptible animals. The briefest exposure at room temperature permitted by the conditions resulted in an association of the virus with the cells, which withstood many washings of the latter. The fixation thus indicated took place not only upon living cells but upon those killed by heat, ultraviolet light, and water respectively, and often was as considerable. Incubation of the material with immune serum in vitro, followed by repeated washings prior to infection, resulted in neutralization of the virus associated with dead cells, whereas these procedures were without effect when the cells were alive. The possibility that serum antibodies accumulated on the dead cells and were carried into the final inoculum was ruled out by appropriate tests. Suspensions of individual, washed cells procured from cultures of Shope tumor tissue, or from rabbit embryo cultures inoculated with vaccinia, were found to carry the virus.

A Comparison of the Tar Tumors of Rabbits and the Virus-Induced Tumors

By tarring the ears of domestic and cottontail rabbits tumors have been procured for comparison with others experimentally induced with the Shope virus. 1 The tarred rabbits were strictly isolated. The growths caused by virus regularly developed from the surface epidermis and were papillomas varying little in structure, whereas not a few of those consequent on tarring originated from the skin appendages, with result in a wider morphological variety. The tar papillomas were scattered, discrete and often punctate in origin; so too were the papillomas due to virus when this had been appropriately inoculated. The growths due to tarring appeared only after it had been repeated often enough to cause general hyperplasia of the epithelium, together with complex connective tissue alterations; and many of them retrogressed after tarring was stopped. The virus tumors, on the other hand, arose on the basis of the slight epidermal trauma incident to inoculation, and their progression was followed, not preceded, by connective tissue changes. The virus evidently needed no help,—though the growths it caused could be stimulated to rapid enlargement by connective tissue disturbances experimentally induced. 2 The unknown cause of the tar papillomas, on the other hand, was effective only when epithelial and connective-tissue disturbances had long existed, becoming independent thereof only after the growths had undergone considerable development, and often not even then. The tar papillomas were structurally much more irregular than early virus papillomas, as would follow from the disturbance of the underlying connective tissue, which was of a sort to bring about corresponding irregularities in the virus tumors. The surface of the tar papillomas often underwent maceration because covered, whereas the exposed surface of the virus growths consisted of dry, keratinized material. When due allowance had been made for these differing conditions of incidence and growth, the resemblance between the tar and virus papillomas was found to be close.

The concentrating activity of the gall bladder

In a previous paper we have noted the fact that the fluid which collects in bile ducts experimentally obstructed is an inspissated, tarry bile when the ducts communicate with the gallbladder, whereas in ducts unconnected with this viscus the fluid is thin and soon becomes free from pigment and cholates. It has long been recognized that the gall-bladder must have a concentrating function, since bladder bile is more concentrated than duct bile from the same animal; and continued functioning during stasis will explain the tarry bile then found. The inspissation occurs so rapidly as to raise the question whether concentration of the bile in periods of intermittent or partial stasis may not be an important favoring element in the formation of gall-stones. To determine the rate of concentration advantage has been taken of the arrangement of the hepatic ducts in the dog. There are three of these, which unite to form a common duct, with the cystic duct emptying high up into the central one. Through an opening near the lower end of this last a catheter was pushed into the neck of the gall-bladder, which was emptied and washed with salt solution; and the duct was ligated after the catheter had been withdrawn. The bile from the middle lobes of the liver had now no way of escape save into the gall-bladder. That from the lobes to either side still reached the common duct, but from this it was collected into a rubber balloon placed in the peritoneal cavity. The laparatomy incision was completely closed. The dogs tolerated the operation well. Control experiments in which a second balloon was substituted for the gall-bladder showed that the separated portions of bile differed little in their pigment content, which was taken as the index to concentration.