Hormonally induced tumors of the reproductive system of parabiosed male rats

Parabiosis of intact male rats to castrated males or oophorectomized females for a period of approximately 20 months resulted in three interstitial cell tumors of the testis. When unilateral nephrectomy was added to the parabiotic procedure in ten pairs, eight interstitial cell tumors of the testis and four adenocarcinomas of the prostate occurred in the target male parabionts. These changes were preceded by elevations in luteinizing and follicle-stimulating hormone levels in the serum of the castrates and high levels of testosterone and, to a lesser degree, of androstenedion in the target partners developing the tumors.

Is breast cancer a result of endocrine targeting? (How women differ from rats or mice)

Parabiosis of female rats with castrate males or oophorectomized females produces carcinoma of the breast in the majority of intact females. When unilateral nephrectomy of each partner is added to the procedure, the incidence is 100 percent. Radioimmunoassays for luteinizing hormone (LH), follicle-stimulating hormone (FSH), prolactin, estradiol and progesterone have been performed on the sera of these rats. The pathogenesis of the breast carcinomas is discussed in the light of these results. An attempt to weigh various factors thought to be involved in causing human and experimental rat cancer of the breast suggests significant differences of a quantitative nature.

Structural comparisons of the aggregates of tobacco mosaic virus protein

The coat protein of tobacco mosaic virus forms numerous aggregates, including the small A-protein, the disk, and two helical forms. The structures of the disk, the helical protein forms, and the virus are compared. Most of the differences are in the conformation of the chain between residues 89 and 113, which lies in the region of protein at the center of the virus, inside the RNA. It is disordered in the disk, but has a fixed conformation in the virus and the protein helices. The differences between the virus and the two helical protein forms are largely in the conformations of arginines and carboxylic acids in this region.

Late effects of successive massive doses of radiation on parabiont rat pairs

Parabiosis of rats permits one partner to survive 1000 R X-radiation if the other is shielded. This dose to the previously shielded partner after intervals of 5, 10 or 30 days tests the ability of the first irradiated partner to recover and, in turn, support the second. The effectiveness of this can be measured by the late effects induced in the pair. Lifespan was shortened by 100--150 days following a 5-day interval, by 30 days following a 10-day interval and not shortened following a 30-day interval. The incidence of leukaemia was about 6 per cent in each group, close to that in control pairs. Shortening the interval between the irradiations decreased the average age of death from leukaemia. No solid lymphoid tumours were induced in the doubly irradiated pairs. The incidence of osteogenic sarcoma was 1.6 per cent in controls and 12.9 per cent in the pairs with both partners irradiated.

Mammary and other tumors as a response to radiation and multiple stresses

Parabiosis of paired NEDH rats and subsequent irradiation of one produced multiple stresses, particularly altered hormonal milieu. Benign mammary tumors developed in 8.6% of the control pairs, 12.7% of the shielded partners, and 19.7% of the irradiated rats. Mammary cancers developed in 5% of control pairs, 14.2% of the shielded partners, and 11.9% of the irradiated rats. With increased amounts of prolactin, the rate was 50% in shielded partner, 10% in the irradiated rats. Mesenchymal sarcoma develop at the anastomosis in parabiont rats. Their incidence rate in single controls is 3.1%, in parabiont control pairs 12.5%, in pairs with one partner irradiated 16.6%, and with both irradiated 23.1%. The incidence rate in other parts was increased threefold over controls in the irradiated partners. Radiation appears to be the dominant factor in both mammary and anastomotic tumors.

Tissue enzyme changes in parabiotic rats with subcutaneous lymphoma or fibrosarcoma

A solid lymphoma implanted into normal inbred Kx rats and one partner of parabiotic pairs caused appreciable decreases in hepatic ornithine aminotransferase and arginase about a week earlier (4-6 days after implantation) in single hosts than in parabiotic hosts. By 18-21 days significant decreases in both enzymes were apparent in the host partner also. The hepatic thymidine kinase showed a fivefold elevation in single hosts 4 days after implantation; by 14 days in its levels were about 200 times above normal and had also risen in the parabiotic hosts (20-fold) and host partners (fourfold). Implantation of fibrosarcoma caused qualititatively similar but generally less pronounced changes in these three enzymes in livers of single hosts, parabiotic hosts, and host partners. The splenic thymidine kinase 14 days after implantation was increased from control levels of about 3 U/g to 50.6, 44.8, and 13.5 U/g in single hosts, parabiotic hosts, and host partners, respectively. At later stages, 17-20 days after implantation of the lymphoma, appreciable amounts of thymidine kinase appeared in the plasma: The units of activity per milliliter were 6.2 in single hosts, 0.79 in parabiotic hosts, and 0.55 in host partners (control less than 0.05). Our observations on the changes in hepatic and splenic enzymes in parabiotic rats suggest that effects of neoplasms on distant host tissues are mediated by humoral factors. The less pronounced responses in parabiotic than in single hosts indicate that the tumor-free partner affords some "protection" against these systemic effects.

Carcinoma of the prostate in irradiated parabiotic rats

Twelve hundred fifty-two pairs of male NEDH rats were parabiosed, one partner received a single dose of 1000 R X-radiation, and the other rat was shielded with lead. Eleven hundred twenty pairs survived over 200 days and constitute the basis of this report. Twenty-five of the irradiated partners developed malignant tumors of the prostate, 19 of which were adenocarcinomas. One adenocarcinoma appeared in the shielded partners and one in a control group of 586 parabiosed and single rats. The long-term effect of a single dose of 1000 R whole-body X-radiation is weakly carcinogenic for the rat prostate.

Structure of RNA and RNA binding site in tobacco mosaic virus from 4-A map calculated from X-ray fibre diagrams

The structure of tobacco mosaic virus has been solved to a resolution of 4 A using fibre diffraction methods. The general fold of the protein is clear, the conformation may be deduced in many places, and the conformation of the RNA and its interaction with the protein can be seen.

A transplantable insulinoma in the rat

A transplantable insulinoma was developed in inbred albino rats of the NEDH strain. The original tumor, 1 cm in diameter, was removed from the pancreas of a male parabiont 566 days folowing 1000 rads (10J/kg) of total body x-irradiation. The time required for implanted fragments to grow to 0.5-1.5 cm in diameter decreased from 5-8 months in the first generation to 2-5 months in the seventh generation. Successful transplantation in male animals followed for 4 or more months after transplantation was significantly greater than in female animals followed for a similar period of time (96% versus 69%). Light and electron microscopy revealed that the tumors consisted predominantly of well-granulated beta cells. Ultrastructural studies also showed small numbers of D-cells. Tumor extracts contained an average of 223 units of immunoreactive insulin and 25.9 mug of immunoreactive somato-statin per gram wet weight of tissue. Tumors generally produced increasingly profound hypoglycemia within 2-4 months following transplantation, with plasma glucose levels frequently falling to 40 mg/100 ml or lower prior to death. Removal of tumors from chronically hypoglycemic animals resulted in transient rebound hyperglycemia with plasma glucose levels above 300mg/100 ml within the first 24 hr and a gradual decline to normal levels of 129 mg/100ml in 2-4 days. These observations correlated with findings of marked atropy and degranulation of the beta cells in the pancreata of tumor-bearing animals, and with gradual return of normal light microscopic morphology following tumor removal.

Safe handling of tissue containing radioactive substances

Patients recently treated with radioactive isotopes may present problems or even hazards during physical examination, operation or autopsy, especially following the use of iodine isotopes and 198Au. 32P is rarely a significant hazard. Contamination of victims of radiation accidents may be a problem initially, but they are usually promptly decontaminated. Guidance of the hospital's radiation safety officer is helpful, particularly with regard to handling of contaminated persons or materials. Long-lived isotopes, such as radium or thorotrast, are usually present in too low concentration to be dangerous. Projected use of artificial hearts powered by plutonium should not be hazardous because of adequate shielding of the source.

Skeletal and tissue lesions resulting from exposure to radium and fission products

The chief effects of absorbed radionuclides and external radiation are radiation osteitis, disturbed bone growth, myelofibrosis and bone tumors. The lesions are dependent in part on localization and character of the radiation and in part on dose. Data on radium have been derived from dial painters, radium chemists and those treated some years ago by oral or parenteral administration.

The effect of parabiosis on life-span of rats stressed by radiation

The life-spans of four series of NEDH rats were compared: (1) single control rats, (2) single rats irradiated with 1000 R, (3) control parabiont rats, (4) parabiont rats one of which had received 1000 R. The stress of radiation (1000 R) produced a median life shortening of 571 days in single rats. Parabiosis followed by irradiation (1000 R) of a member of the pair shortened life 132 days. Parabiosis alone produced a median life shortening of 62 days. Ninety percent of the older irradiated parabiont pairs died with one or more tumors present. Parabiosis largely protected animals from the gastrointestinal radiation syndrome.

The effect of nephrectomy on the incidence of breast carcinoma in irradiated parabiosed rats

The incidence of carsinoma the breast in parabiosed female NEDH rats is 2.5%. When one member of such a pair is irradiated, the incidence rises to 11% in the irradiated partner and 10% in the nonirradiated partner. If in such a pair of rats one kidney is removed from each partner, the incidence of breast carcinoma rises fivefold in the nonirradiated partner. The factors involved in such an increase probably have to do with alteration in retention, interchange, and feedback of the pituitary and ovarian hormones.