Quality assurance for pathology in rodent carcinogenesis tests

A large scale national carcinogenesis testing program requires quality assurance procedures for each scientific discipline, including pathology. The NCl Carcinogenesis Testing Program's pathology procedures involve the necropsy examination, histology, histopathologic diagnosis, data recording, and report writing. Each phase of the program requires specific quality assurance procedures, some of which are clerical, others scientific. In the latter case, a consensus from a group of pathologists serves to resolve differences of opinion. Only with the implementation of quality assurance procedures will the confidence in these tests be assured and quality maintained. Subsequently, modifications to established protocols may be discussed and accurately evaluated.

Clinical and pathologic conditions of female nude (athymic) mice in two conventional maintained colonies

Two colonies of female outbred nude (athymic) mice were maintained by conventional standards of husbandry, but with special sanitary methods and segregation from other rodents. A total of 1,526 mice entered the colonies. Of these, 802 were untreated and most remained healthy. Necropsies were performed on 312 untreated mice that were sick and were killed or died naturally, and the tissues were examined microscopically. Clinical and pathologic conditions in the untreated mice included subcutaneous abscessation, dermatitis, subcutaneous edema due to glomerulonephritis (nephrotic syndrome), rectal prolapse, and lymphomas and other neoplasms.

Hypercalcemia of malignancy. Animal model: VX-2 carcinoma of rabbits

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HLA antigens in persistent palmoplantar pustulosis and its relationship to psoriasis

HLA typing was performed on 93 patients with persistent palmoplantar pustulosis. The incidence of either HLA B13 or BW17 was not significantly increased as compared to controls. In addition the frequency of BW35 was no different from controls. However, the present results document a significantly increased frequency (38.7%) of B8. Taken together these data are good evidence that palmoplantar pustulosis is a genetically distinct disease entity from psoriasis vulgaris, despite the increased incidence of psoriasis in the condition.

Evaluation of hepatocellular neoplasms in mice

Thirty C3H-AvyfB male mice from 3 to 15 months of age were killed, and the genesis of their hepatocellular neoplasms was studied. As the mice aged, the number of tumors per liver and mean diameter of the tumors increased. Histologically, the smallest tumors were composed of solid sheets of cells and were better differentiated than the largest tumors. Small foci of hepatocytes in prominent trabeculae formation was a common characteristic of large tumors. In addition, 18 metastatic hepatocellular carcinomas observed in aged C3H-AvyfB, C3HfC, C3H, C3HfB, (C3HfB x YBR)F1, or C57BL/6 mice were also included for a morphologic study of their primary and metastatic lesions. Invariably, the pulmonary metastases were composed of a well-differentiated sheet of hepatocytes that resembled those in the solid liver tumors. The smallest hepatocellular neoplasms appear to represent early stages in the development of metastatic hepatocellular carcinoma.

Pancreatic carcinogenesis and naturally occurring pancreatic neoplasms of rats and mice in the NCI carcinogenesis testing program

Over two hundred chemicals were examined in a two year rodent bioassay system for possible carcinogenicity. Of these, only nitrofen significantly increased the incidence of neoplasms of the exocrine pancreas of rats or mice (female Osborne-Mendel rats); azinphosmethyl was the only agent tested which significantly increased the incidence of islet-cell tumors of rats or mice (male Osborne-Mendel rats). The use of the rat (Osborne-Mendel or Fischer 344) and mouse (B6C3F1) as models for the detection of chemically-induced pancreatic neoplasms also was investigated. The incidences of specific neoplasms of the exocrine or endocrine pancreas produced by all chemicals tested were combined and compared with the combined incidences of similar neoplasms in control animals in order to increase the sensitivity of the test. The data obtained through this procedure suggests that the male rat may be a good, sensitive model for the detection of islet-cell tumors.

Dose response to intrarectal administration of N-methyl-N-nitrosourea and histopathologic evaluation of the effect of two retinoids on colon lesions induced in rats

Male F344 rats, 8 weeks of age, were given 16 intrarectal administrations of N-methyl-N-nitrosourea (NMU) at one of three dose levels over a period of 8 weeks. Five days after the final NMU instillation, rats were placed on one of three diets: chow with gelatin beadlets, chow with beadlets containing 0.024% 13-cis-retinoic acid, or chow and beadlets with 0.006% of the trimethylmethoxy phenyl analog of retinoic acid ethylamide. Groups of 20-40 rats were killed at 22-26 weeks after the first carcinogen treatment. The number of rats with colon carcinoma and the number of tumors per rat were dose related. In addition, "blind" histopathologic evaluation of four predesignate colon locations revealed a dose-related incidence of microscopic preinvasive and invasive colon carcinomas. The feeding of diets containing these two retinoids did not significantly alter the incidence of these parameters of carcinogenesis or the mean histopathologic score at predesignated colon locations for preinvasive or invasive neoplastic lesions. Over 90% of the colon neoplasms induced were invasive tubulopapillary adenocarcinomas. The diameters of the tumors correlated significantly with degrees of invasion of the colons. Only 1 tumor (a signet ring carcinoma) metastasized to the peritoneal cavity. Only 2 of 300 rats treated with NMU had tumors at sites other than the colon.

Mapping of functions in the R-plasmid R388 by examination of deletion mutants generated in vitro

Mutant plasmids in which large segments of R388 DNA are deleted were constructed in vitro from two R388::TnA (Tn801) plasmids, using the BamHI site of TnA and the BamHI and BglII sites of R388. These deletion mutants permitted mapping of genetic functions into the restriction map of R388.

Pulmonary pathology of the motheaten mouse

Mice, homozygous for the motheaten gene, developed an unusual pneumonia that was the cause of natural death of mice by 7 weeks of age. Initial lesions consisted of focal accumulations of alveolar macrophages in alveoli, especially adjacent ot bronchioles. Needle-like crystals formed in lysosomes of macrophages and numerous macrophages with crystals filled most alveoli in 5- to 7-week-old mice. Although motheaten mice had lesions in other tissues and were shown by other investigators to have immunological defects, the unusual pneumonia was the only lesion severe enough to cause death.

Acute toxicity of maytansine in F344 rats

The toxicity of maytansine given by sc administration was studied in 5-week-old mald F344 rats. The LD50 (14-day) was 0.48 mg/kg. A dose response to drug administration was indicated by body weight changes and diarrhea. A single, acutely toxic dose of maytansine was shown to possess marked activity against dividing cells which was regarded as an important factor in the pathogenesis of acute lesions in tissues with a normal high rate of cell division. Histologically, mitotic figues were observed in many tissues from 6 to 24 hours after drug administration. Subsequently, necrotizing lesions led to atrophic changes in gastrointestinal tract mucosa, thymus, spleen, bone marrow, and testis. Maytansine also induced hemorrhagic lesions in parenchymatous organs and brain and perivascular monomuclear infiltration in the meninges, and chromatolysis and vacuolation of dorsal root ganglion cells, accompanied by clinical signs of ataxia. Ulcerative skin lesions were observed at the sc site of drug administration.

Naturally occurring mouse hepatitis virus infection in the nude mouse

A group of athymic nude mice developed an unusual chronic wasting disease within 1-3 months after their arrival into the laboratory. Affected nude mice had severe, acute-to-chronic, active hepatitis with multinucleated giant hepatocytes and fibrosis. Vascular and central nervous system lesions were frequently present, giant cell peritonitis, ascites, and multinucleated giant cells in the intestinal epithelial villi were less frequently observed. Mouse hepatitis virus was isolated from the livers of three mice with lesions. The virus, when inoculated into nude mice, produced lesions similar to those observed in the natural outbreak.

Ultrastructural comparison of differentiation of stem cells of murine adenocarcinomas of colon and breast with their normal counterparts

Two rats with chemically induced transplantable adenocarcinomas of the colon were given pulses of [3H]thymidine, and autoradiography with electron microscopes was used to compare the degrees of differentiation of the stem cells of the tumor and colon. The best differentiated portions of the tumor had acini composed of vacuolated, mucous, and argentaffin cells in various stages of differentiation. Vacuolated and mucous cells incorporated [3H]thymidine and corresponded in degree of differentiation to that of their labeled normal counterparts in the normal colon. An exceedingly undifferentiated labeled cell, hitherto undescribed, was identified in the tumor and crypts of the colon; this may be an undifferentiated colon stem cell that differentiates into vacuolated and mucous stem cells and/or into argentaffin cells. Normal stem cells of the breast and malignant stem cells of spontaneous adenocarcinomas of the breast of C3H mice had comparable degrees of differentiation. Since normal stem cells in these tissues were as undifferentiated as the least differentiated stem cells of the tumors, there is now no need to postulate dedifferentiation as a mechanism to explain the undifferentiated appearance of tumors.

Prevention of renal failure in rats receiving cis-diamminedichloroplatinum(II) by administration of furosemide

The clinicopathological signs of renal failure induced in rats by weekly i.v. administration of cis-diamminedichloroplatinum(II) were prevented by pretreatment with furosemide. Weight loss, anemia, and generalized toxic effects of the drug were not effected by furosemide.

Histogenesis and Morphology of periosteal sarcomas induced by FBJ virus in NIH Swiss mice

FBJ virus was injected i.p. into 145 neonatal NIH Swiss [N:NIH(s)] mice. Eighty mice developed a total of 110 neoplasms by 5 months of age. The mean latent period of the tumors was 71 days (26 to 145) postinjection. The frequency of occurrence of neoplasms at different sites was: diaphragm, 45%; ribs, 14%; vertebrae, 14%; femora, 9%; pelvic bones, 5%; tibiae, 4%; sternebrae, 3%; and inguinal area, 7%. The neoplasms were characterized histologically by elongated or rounded cells associated with an abundant connective tissue stroma. Occasional areas of bone formation and apparent osteoid metaplasia were seen. Bone tumors appeared to arise from periosteal cells, to grow by expansion, and to invade locally, but they failed to metastasize. Neoplasms of the diaphragm originated in the central aponeurosis and appeared histologically similar to bone neoplasms. Histochemical studies demonstrated abundant alkaline phosphatase in tumor cells, and ultrastructural observations revealed subcellular characteristics of osteoblasts and chondroblasts. Tumors were readily transplantable and had histopathological characteristics similar to those of the primary viral-induced tumors. The results of this study indicate that the FBJ virus induces in NIH Swiss mice a unique type of chondroosseous neoplasm derived from periosteal cells which has a resemblance to human juxtacortical (parosteal) osteosarcoma.

A double-blind trial of clomocycline in the treatment of persistent palmoplantar pustulosis

Sixty patients with persistent palmoplantar pustulosis (PPP) were treated with clomocycline (Megaclor) in a double-blind, cross-over trial in an attempt to establish whether the condition responds to tetracycline. Each patient received 3 months each of clomocycline and placebo in random order. Forty patients completed the trial. Twenty-two failed to respond to either treatment, fifteen improved on clomocycline, two improved on placebo and one placebo and one improbed on both treatments. These results are highly significant (P = 0-003) and suggest that clomocycline may suppress pustulation in some patients. The twenty-two 'non-responders' were compared with the eighteen 'responders' for sex, age, length of history and associated psoriasis but no significant differences were found. Difficulties in assessment and the possiblity of improvement deing due to spontaneous remission are discussed. Further follow-up of both groups suggested that clomocycline used over long periods favourably influenced the course of the disease in the 'responder' group.