International Harmonization of Nomenclature and Diagnostic Criteria (INHAND): Progress to Date and Future Plans.

The International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice proposal (INHAND) has been operational since 2005. A Global Editorial Steering Committee manages the overall objectives of the project, and the development of harmonized terminology for each organ system is the responsibility of the Organ Working Groups, drawing upon experts from North America, Europe, and Japan. Great progress has been made with 9 systems published to date--respiratory, hepatobiliary, urinary, central/peripheral nervous systems, male reproductive and mammary, zymbals, clitoral, and preputial glands in Toxicologic Pathology and the integument and soft tissue and female reproductive in the Journal of Toxicologic Pathology as supplements and on a Web site--www.goReni.org. INHAND nomenclature guides offer diagnostic criteria and guidelines for recording lesions observed in rodent toxicity and carcinogenicity studies. The guides provide representative photomicrographs of morphologic changes, information regarding pathogenesis, and key references. The purpose of this brief communication is to provide an update on the progress of INHAND.

Heparin reacts with and inactivates nitric oxide.

Although heparin is a well-known anticoagulant, in some cases it promotes a prothrombotic state and does so through both antibody-dependent and antibody-independent platelet activation. In this study, heparin was found to reverse the antiplatelet effect of an NO donor. S-nitroso-glutathione (SNO-Glu), with an EC(50) of 1.8 U/mL. Ultraviolet/visible spectral analysis and the Griess assay showed that increasing heparin concentrations on a dose-dependent basis eliminated acidified NO(x) species. Since heparin is a heterogeneous mixture of glycosaminoglycans, the effects of six different heparin disaccharides were compared with various substitutions on the hexose rings to determine which functional group(s) of the polysaccharide interact with acidified NO(x). Among the six disaccharides tested, only types I-S and II-S had the effect, suggesting that the sulfamino-group at the C2 position of the glucosamine moiety was critical for the elimination of acidified NO(x) species. Mass spectrometry experiments gave results consistent with these observations, indicating that only the I-S and II-S heparin disaccharides were modified upon treatment with NaNO(2)/HCl. Negative-ion electro-spray ionization MS and tandem MS analyses of the native compounds and their deuterium-labeled analogs confirmed that the reaction products from nitrosation of these N-sulfated disaccharides had eliminated the C2-sulfamino-moiety and replaced it with methoxide derived from the solvent. Participation of the 6-sulfato-substituent appears to facilitate the elimination reaction. These data show that heparin can impair the antiplatelet properties of nitric oxide by interacting with the nitrosating species, and suggest that heparin-like glycosamino-glycans may interact with endothelium-derived nitric oxide in vivo to regulate the bioactivity of this important antiplatelet and vasorelaxant substance.

Hepatotoxicity and carcinogenicity in female Sprague-Dawley rats treated with 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD): a pathology working group reevaluation.

Risk assessment for 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) has been based in part on the incidences of liver neoplasms in female Sprague-Dawley (SD) rats reported in a 2-year study conducted by Dow Chemical Corporation and published in 1978. In the years subsequent to the Dow report, the criteria for the diagnosis of proliferative hepatocellular lesions in the rat have been refined based upon ongoing study of these lesions. Because of this, PATHCO, Inc., was requested to conduct an independent review of the liver slides from the Dow TCDD study in order to assess how the current terminology might impact on interpretation of proliferative liver lesions in rats compared to the terminology used in the past. In March 1990, a pathology working group (PWG) was convened to review proliferative lesions in the livers of the female rats. The results of the PWG's evaluation of the microslides indicated a trend in tumor incidence similar to that published in 1978 but with a lower incidence of tumors in the middle and high dose females. Based on the morphologic findings, including the fact that the tumors were predominantly benign and usually associated with lesions of hepatic toxicity, the PWG considered this study to demonstrate a weak oncogenic effect of TCDD in the livers of female SD rats. As a result of its review, the PWG noted that in order to establish a relationship between the toxic hepatitis and the hepatocellular neoplasms, an independent review and grading of the toxic lesions in all female rats would be required.(ABSTRACT TRUNCATED AT 250 WORDS)

Tumors of the skin in the HRA/Skh mouse after treatment with 8-methoxypsoralen and UVA radiation.

8-Methoxypsoralen (8-MOP) with and without UVA radiation was administered to HRA/Skh mice (36 animals per treatment group) three times a week in the feed for a total dose of 9-80 mg/kg/week for 52 weeks. Most of the animals at the top dose of 8-MOP with UVA radiation had developed skin toxicity and/or skin tumors by 52 weeks. The skin lesions seen after treatment with 8-MOP and UVA radiation were characterized as squamous cell hyperplasia, squamous cell papilloma, and squamous cell carcinoma and are similar to what has been reported in humans after exposure to 8-MOP and UVA. Squamous cell hyperplasia and acute inflammation of the cornea were also seen in some of the treated female mice. Oral administration of 8-MOP and UVA did not result in a carcinogenic response to other organ systems. There were no increases in skin neoplasms after 8-MOP or UVA radiation alone. 8-MOP given in combination with UVA was carcinogenic to the skin of mice at dose levels similar to those used to treat psoriasis in humans.

Splenic fibrosis and sarcomas in F344 rats fed diets containing aniline hydrochloride, p-chloroaniline, azobenzene, o-toluidine hydrochloride, 4,4'-sulfonyldianiline, or D & C red No. 9.

In six carcinogenicity bioassays, male and female F344 rats were fed diets containing aniline hydrochloride (CAS: 142-04-1; hydrochloride benzenamide), p-chloroaniline (CAS: 106-47-8), azobenzene (CAS: 103-33-3), o-toluidine hydrochloride (CAS: 636-21-5), dapsone (CAS: 80-08-0; 4,4'-sulfonyldianiline), or D & C red No. 9 [CAS: D85500000; 5-chloro-2-[2-hydroxy-1-naphthalenyl)azo)-4-methylbenzenesulfon ic acid, barium salt]. The rats, from 6 weeks to 2 years old, were given the compounds at two dose levels, the estimated maximum tolerated dose and one-half that dose. In all six bioassays, dose-dependent incidences of splenic sarcomas and fibrosis were seen, with the highest incidences in male rats. Fibrosis occurred in the splenic parenchyma and/or the capsule. Fatty infiltration also was seen in the spleen. Sarcomas appeared to arise in the splenic red pulp or splenic capsule, usually in association with areas of parenchymal and capsular fibrosis and pigmentation. Larger tumors metastasized to the peritoneal cavity and abdominal organs. In some rats there was marked osseous metaplasia when the primary tumor metastasized to peritoneal surfaces. Other, less common, splenic neoplasms included hemangiosarcoma and hemangiopericytoma. Some rats had such extensive peritoneal involvement that the site of origin of their sarcoma was difficult to determine.

Neoplastic and nonneoplastic lesions in aging (C57BL/6N x C3H/HeN)F1 (B6C3F1) mice.

Neoplastic and nonneoplastic lesions in untreated (C57BL/6N x C3H/HeN)F1 (B6C3F1) mice used as controls in carcinogenesis tests were tabulated and evaluated. The most common neoplasms in 2,543 male mice were hepatocellular adenomas and carcinomas. In 2,522 female mice, common tumors were lymphomas, leukemias, pulmonary adenomas and carcinomas, hepatocellular adenomas and carcinomas, and pituitary adenomas. The risk of developing most neoplasms increased with the age of the mouse. Hepatocellular carcinomas metastasized in 12% of the animals with these tumors. Other than lymphomas and leukemias, few other tumors metastasized. Nonneoplastic lesions included cystic hyperplasia of the uterus, nephritis, ovarian and uterine cysts, inflammatory lesions of the lung, mineralization in the brain, and focal hyperplasias in several tissues. The focal hyperplasias in lung and pituitary, adrenal, and thyroid glands were suggestive of the early stages of neoplasia. Comparative aspects of lesions in aging mice and their interpretation in carcinogenesis tests are discussed.

Histopathology of neoplastic and nonneoplastic hepatic lesions in mice fed diets containing tetrachlorvinphos.

Tetrachlorvinphos was fed at 8,000 or 16,000 ppm in diets to male and female (C57BL/6N X C3H/HeN)F1 mice for 80 weeks. Surviving mice were killed at 92 weeks, and all mice were completely necropsied. A high incidence of unusual nonneoplastic hepatic lesions in treated mice was present and characterized by pericellular fibrosis, hepatocyte nuclear pleomorphism, and intrasinusoidal foci of macrophages with intracytoplasmic crystalline structures. From 84 to 94% of the treated male mice and from 21 to 23% of the treated females had hepatocellular neoplasms. Only 17% of the control males and 7% of the control females had liver tumors. The induced tumors were frequently multiple in the liver, whereas the tumors in the controls were usually singular. The morphology of 241 liver tumors in 110 treated mice was different from that of tumors in controls. Liver tumors in control mice were generally composed of small basophillic hepatocytes. In treated mice, tumors were hepatocellular carcinomas composed of solid sheets of large basophilic or eosinophilic hepatocytes. Foci of prominent trabecular formation were seen in 51 tumors. Fifteen tumors were composed of small basophilic hepatocytes with oval cells interposed among them. Foci of capillary formation were noted in 3 of these tumors. In addition, 7 more typical hemangiosarcomas forming sinusoids and with thrombosis were observed.

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.

Expression of RNA of an endogenous replication-defective retrovirus in rat mammary adenocarcinomas induced by 7,12-dimethylbenz[a]anthracene.

An investigation into the possible relationship between chemical carcinogen induction of rat mammary tumors and the expression of an endogenous retroviral genome was initiated. Mammary tumors were induced in female SD rats with 7,12-dimethylbenz[a]anthracene (DMBA). Tumors, identified histologically as mammary adenocarcinomas, were analyzed for RNA of a replication-defective endogenous retrovirus or RNA of a helper-independent endogenous type C virus. Expression of RNA of the replication-defective virus was detected in mammary tumors weighing 0.2--2.0 g. Larger tumors, for which histologic examination revealed proportionally more fibroblastic tissue than epithelial cells, did not contain comparable concentrations of this viral RNA. RNA homologous to a helper-independent rat type C retrovirus was not detected in tumors of any size. A cell line was established from a primary DMBA-induced mammary adenocarcinoma and appeared similar to the small mammary tumors with respect to endogenous type C viral RNA expression. We discuss possible implications of the expression of endogenous replication-defective viruses for use as markers for the effects of chemical carcinogens.

A model of fulminant hepatic failure in the rabbit.

A highly reproducible model of fulminant hepatic failure was developed by administering intravenously the selective hepatotoxin galactosamine hydrochloride (4.25 mmoles per kg) to genetically uniform rabbits. The great majority of rabbits died between 21 and 44 hr after injection following a period of coma which lasted 2.6 hr on average. Serum biochemical tests and liver histology reflected massive hepatic injury. Changes in plasma ammonia and amino acid concentrations, in coagulation parameters, and in the electroencephalogram were similar to those found in human fulminant hepatic failure. This model appears promising for future studies of the pathogenesis and treatment of fulminant hepatic failure.

13-cis-Retinoic acid: inhibition of bladder carcinogenesis induced in rats by N-butyl-N-(4-hydroxybutyl)nitrosamine.

Transitional cell carcinoma was induced in the bladders of male Fischer rats by 12 oral doses of the carcinogen N-butyl-N-(4-hydroxybutyl)nitrosamine. Feeding of 13-cis-retinoic acid after completion of carcinogen treatment diminished the number and severity of cancers and other proliferative lesions of the bladder.

Nine simultaneous primary tumors in a Boxer dog.

An aged Boxer dog had 9 distinct primary tumors: chemodectoma, osteosarcoma, bronchiolo-alveolar adenocarcinoma, interstitial cell tumor, seminoma, basal cell tumor, fibropapilloma, adrenal cortical adenoma, and pancreatic adenoma. From this report, as well as from other studies, it is clear that Boxers have special susceptibilities to a variety of tumors. Analysis of clinical data on canine tumors indicated that the risk of Boxers for multiple tumors is only slightly higher than all tumors, indicating little or no specific predisposition for multiple tumors. In Boxers, however, certain tumor types occurred more frequently as multiple primary tumors than would be expected by chance.

Suppression of autoimmunity in NZB mice with steroid-sensitive X-radiation-sensitive syngeneic young thymocytes.

NZB mice spontaneously lose thymic regulatory or suppressor cells and subsequently develop autoimmunity and lymphoreticular hyperplasia. Treatment with 2-week-old syngeneic thymocytes every 2 weeks starting at 4 weeks of age suppressed these disease manifestations. The active thymocyte subpopulation was found to be sensitive to corticosteroids and X-irradiation.