Neoplastic and life-span effects of chronic exposure to tritium. II. Rats exposed in utero

A study was conducted to determine the effects on neoplasia incidence and life-span of exposure in utero to a major environmental radionuclide. Sprague-Dawley rats were continuously exposed to tritiated water (HTO) from conception through birth in doses of 0, 1, 10, 50, and 100 muCi HTO/ml body water. HTO administration was terminated at birth. Calculated cumulative doses during gestation were approximately 0, 6.6, 66, 330, and 660 rads of total body irradiation. Under these exposure conditions, the two highest doses resulted in sterile offspring. Animals surviving through 30 days postnatally were defined as the study population and observed until their deaths. Intrauterine exposures to doses up to 66 rads had no significant effects on either sex with respect to life-span, overall neoplasia incidence, incidence rate, or onset of mammary fibroadenomas. Females exposed to 330 or 660 rads were sterile and had lower incidence rates of mammary fibroadenomass than did controls; at 660 rads females had a lower incidence of overall neoplasia and reduced mean life-spans. Sterile male offspring had reduced mean longevity after irradiation at 660 rads. Regardless of dose group, females had significantly higher incidences of neoplasia and longer life-spans than males.

Neoplastic and life-span effects of chronic exposure to tritium. I. Effects on adult rats exposed during pregnancy

Female Sprague-Dawley rats were continuously exposed to equilibrium levels of tritiated water (HTO) during pregnancy. The tritium activities were 1, 10, 50, and 100 muCi HTO/ml body water which provided cumulative, whole-body radiation doses of approximately 6.6, 66, 330, and 660 rads. Administration of the radioisotope was terminated at parturition. Throughout their life-spans and at autopsy, the dams showed an increased incidence of mammary fibroadenomas at exposure to 330 and 660 rads. Although the data for the incidence of malignant mammary neoplasms were consistent with a linear dose response, the small numbers of tumors preclude specific definition of the dose-response curve. Postexposure life-spans for dams chronically exposed to 66, 330, and 660 rads during pregnancy were reduced by 14, 24, and 22%, respectively. Accelerated aging was also demonstrated in these rats: The mean age for mammary fibroadenoma onset decreased with an increasing dose of radiation.

Intestinal tumors in mice treated with a single injection of N-nitroso-N-butylurea

N-Nitroso-N-butylurea was injected once at dosage levels of 150 or 75 mg/kg into 3- or 6-week-old male C57BL/L mice. Intestinal tumors occurred in 100% of the mice that survived more than 15 weeks after injection with a high dose of N-nitroso-N-butylurea at 6 weeks of age, and in 35 to 70% of the mice in other treatment groups. These intestinal tumors were seen primarily at the junction of the pylorus and duodenum and in the anterior portion of the small intestine, with a few in the cecum, colon, and rectum. The tumors at the junction were not very invasive tumors and frequently appeared as polypoid growths. Tumors not at this location were adenocarcinomas that invaded all the layers of the gut wall but which did not metastasize. Colorectal tumors were adenomas and adenocarcinomas. N-Nitroso-N-butylurea also induced tumors of the stomach, hematopoietic system, lung, and liver.

Effect of lifetime exposure to aflatoxin b1 in rats

Aflatoxin B1 was fed at 2 ppm in the diet to a group of pregnant F344 rats from the time of conception; it was then fed to their offspring until death. This diet was also given to another group of rats 6-7 weeks old for comparison. The survival time of male rats was significantly shorter than that of the female rats of both groups. However, the survival times of rats of the same sex in both groups did not differ significantly. The major causes of death were hepatic neoplasms with matastases, although some early deaths occurred before neoplasms developed. Most deaths were from a malignant hemorrhagic liver tumor, histologically diagnosed as a hemangiosarcoma, which caused rupture and hemorrhage into the peritoneal cavity or metastases to the lungs. These hemangiosarcomas were readily transplantable and did not produce alpha-fetoprotein. Ultrastructurally, they were composed of poorly differentiated cells resembling endothelial cells. Nodules of hyperplasia induced by aflatoxin B1 sometimes grew large (greater than 1.5 cm), and 2 were transplanted. Approximately 20% of the rats had colon tumors; a few rats had tumors of the kidney, oral cavity, and hematopoietic system.

Dose response to a single injection of azoxymethane in rats. Induction of tumors in the gastrointestinal tract, auditory sebaceous glands, kidney, liver and preputial gland

Male Fischer rats, 6 weeks old, were injected once with one of five doses of azoxymethane. There was a dose response to the carcinogen as determined by weight gain and tumor induction. Rats given the three highest doses developed tumors of the gastrointestinal tract, auditory sebaceous glands, kidney, liver, and preputial gland, whereas rats receiving the lowest doses had tumors mainly of the intestine. Chronic liver lesions in high-dose rats were cirrhosis with megalocytosis, mild fibrosis, nodular hepatocellular hyperplasia, and hyperplasia of bile ductules.

Modification of diethylnitrosamine liver carcinogenesis with phenobarbital but not with immunosuppression

Administration of 40 ppm diethylnitrosamine (DENA) in the drinking water for 10 weeks to male Fischer rats led to hepatocellular carcinoma in 100 percent with metastasis to the lung in 40 percent, of the animals living for the full experimental period of 20 weeks. Concurrent feeding of phenobarbital and DENA for 10 weeks produced cancer of the liver in 77 percent of the animals, but only 9 percent had metastases in the lung. A brief regimen of DENA for 4 weeks, followed by 16 weeks of observation, induced cancer of the liver in only 13 percent of the rats. Administration of phenobarbital, begun 1 week after cessation of DENA intake and terminated at week 20, led to liver cancer in 64 percent of the rodents. Hydroxyurea had no effect on this enhancement. Treatment with a purified gamma fraction of antilymphocytic serum after the DENA did not influence the outcome. Thus phenobarbital given together with DENA reduced the severity of the carcinogenic process, but when it was given after the hepatocarcinogen, it increased the effect.

M. fortuitum and M. chelonei-fast growing mycobacteria. A review with a case report

Infection due to opportunist mycobacteria is considered in general and that due to the fast growing mycobacteria in particular. The group is now seen to contain two facultative pathogens, M. fortuitum and M. chelonei (abscessus), all other synonyms for these two species having been shown to be invalid. Both organisms are ubiquitous and normally harmless; however, following injury or injection, they may cause chronic sub-cutaneous abscesses. Pulmonary lesions have also been described. More recently M. fortuitum has been found to cause osteomyelitis and corneal ulceration and both organisms have been identified in cases of septicaemia associated with renal dialysis. In the past M. chelonei my have been identified as M. fortuitum but although it is more difficult to isolate, it may in fact be the more common cause of disease. A case is reported of an English girl who received a small injury to her shin in Spain. The initial lesion failed to heal and for 18 months there was repeated formation small sinuses in the area. Healing then occurred spontaneously. Histology showed a chronic granuloma and on two occasions a rapid growing mycobacteria resistant to all antibiotics was isolated. This was initially identified as M. fortuitum but finally as M. chelonei and the latter diagnosis was confirmed by differential skin tests. Difficulties in interpretation of these tests are discussed.

Porphyria variegata provoked by contraceptive pill

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Long-term effect of benzene in C57BL/6N mice

Weaning male C57BL/6N mice received repeated subcutaneous injections of benzene in corn oil for 54 weeks. These mice and surviving controls were killed 104 weeks after the first injection. There was no evidence of carcinogenic activity in benzene-injected mice. A high incidence of amyloidosis developed in mice of all treated and untreated groups. Butyinitrosourea, used as a positive control, induced lymphomas or leukemias (in most exposed mice) and intestinal tumors in a few.

Cystoscopy of chemically induced bladder neoplasms in rabbits administered the carcinogen dibutylnitrosamine

Subcutaneous injection of the carcinogen dibutylnitrosamine into male rabbits led to bladder papillomas, hemangiomas, and carcinomas within 17 to 26 months. The progress of the developing bladder lesions was readily followed by cystoscopy.

Lupus vulgaris with tuberculous prostatitis

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