bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphology, Physiology, and Biochemistry of Biliary Epithelia
Authors: Larusso Nicholas F.
Published: April 2009

In this review, we have emphasized the importance of cholangiocytes in biology and pathology and highlighted recent advances in experimental approaches to study these increasingly important cells. It is anticipated that major advances will continue to be made in our understanding of how these cells funciton and the processes which result in their dysfunction. The techniques are now available to allow major inroads in our understanding of the pathobiology of cholangiocytes.
Sinusoidal Lining Cells and Hepatotoxicity
Authors: Laskin Debra L.
Published: April 2009

Treatment of experimental animals with toxic doses of acetaminophen, carbon tetrachloride, phenobarbital, galactosamine, or endotoxin results in an accumulation of macrophages in the liver. These mononuclear phagocytes, as well as hepatic endothelial cells and stellate cells, are activated to release increased amounts of proinflammatory and cytotoxic mediators including hydrogen peroxide, superoxide anion, nitric oxide, bioactive lipids, interleukin 1, platelet activating factor, and tumor necrosis factor α. Each of these mediators has the capacity to induce tissue injury directly and/or augment the inflammatory response. When animals are treated with agents that block macrophage functioning and/or mediator release, xenobiotic-induced hepatotoxicity is reduced. In contrast, treatment of animals with macrophage activators augments toxicant-induced liver damage. These data provide direct support for a role of macrophages and inflammatory mediators in hepatotoxicity.
The Effect of Indomethacin Administration on the Splenic Changes Induced by Estradiol Supplementation in Ovariectomized New Zealand White Rabbits
Authors: Thurmond Thane S. , Ferslew Kenneth E. , Mccracken Malcolm D. , Coogan Philip S.
Published: April 2009

In an effort to elucidate the mechanism by which indomethacin (IN) lessens the stimulatory effect of estradiol (E2) on rabbit splenic red pulp macrophages (RPMs), 39 female New Zealand White rabbits were divided into 10 groups: ovariectomized (OVX) and OVX/ IN at 0.1 and 5.0 mg/kg body weight (bw)/day; sham OVX (SOVX) and SOVX/IN at 0.1 and 5.0 mg/kg bw/day; OVX/25 mg E2 and OVX/25 mg E2/IN at 0.1 and 5.0 mg/kg bw/day; and intact control. Changes in RPM population in response to treatment were measured using a 0-4 histologic grade. Estradiol treatment resulted in increased RPM grade when compared to the OVX groups. Indomethacin addition lowered mean RPM grade in the SOVX/IN 5.0 group when compared to its E2 control group. Indomethacin administration had no significant effect on levels of prostaglandin E 2 in spleen, urine, or blood. Hematocrits were reduced in both OVX and OVX/E2 groups; this decrease was exacerbated by the high IN dose. In summary, the results from this study suggest that the effect of IN on E2-induced RPM activation may be mediated through a nonprostaglandin pathway. The observed hematocrit changes are possibly the result of direct action of IN and E2 on erythrocytes, resulting in their accelerated clearance from the circulation by splenic RPM.
An Epithelioid Cell Type of Amelanotic Melanoma of the Pinna in a Fischer-344 Rat: A Case Report
Authors: Nakashima Nobuaki , Takahashi Kimimasa , Harada Takanori , Maita Keizo
Published: April 2009

An epithelioid cell type of spontaneous amelanotic melanoma in the pinna of an aged albino Fischer-344 (F-344) rat is described. When the rat was necropsied at 109 wk of age, the pinnal tumor was recognized as a white spherical mass of 4 mm in diameter. Histologically, the tumor was observed in the dermis and composed of large round or polyhedral epithelioid eosinophilic cells that were arranged in various-sized cell nests. Immunohistochemistry demonstrated that the tumor cells were positive for S-100 protein and vimentin but negative for keratin and a rat macrophage antigen. Ultrastructurally, a few single membrane-bound premelanosomes that were accompanied by many primary lysosome-like bodies containing very fine granules were present in the cytoplasm of the tumor cells. This study has disclosed that, in addition to spindle cell variants of amelanotic melanomas, an epithelioid cell type of amelanotic melanoma may occur spontaneously in the skin of F-344 rats.
Regulatory Issues of Importance to Developing Anti-HIV Therapeutics
Authors: Hastings Kenneth L.
Published: April 2009

In the United States, before clinical trials with new drugs can proceed, an Investigational New Drug (IND) application must be submitted to the Food and Drug Administration. Applications for drugs intended for the treatment of HIV-related diseases are reviewed by the Division of Anti-Viral Drug Products (DAVDP) within the Center for Drug Evaluation and Research. IND applications must contain adequate preclinical studies to support the safety of the proposed clinical trials. Essential for demonstrating safety are animal toxicology studies in which the drug has been administered in doses, by the route(s) of administration, and over a length of time equivalent to the corresponding parameters proposed for clinical trials. Reproductive toxicology/teratology studies should be conducted early in the development of the drug. Other nonclinical toxicology studies, such as carcinogenicity bioassays, are usually conducted concurrently with clinical trials. The DAVDP has developed a Pre-IND program to assist sponsors in preparing the best preclinical research to support the development of new drugs.
Brief Communication
Authors: Baselmans Anton H.C. , Kuijpers Marga H.M. , Van Dijk Aap E.
Published: April 2009

A case report is given of a very rare spontaneous mast cell tumor in the eyelid of the left eye of a female Wistar rat used in a long-term oral toxicity study. Metastasis of the tumor had occurred in the mandibular lymph nodes and in the liver. Clinically, the animal showed blepharospasm, dacryorrhoea, and exophthalmus. Hematologic findings included slight eosinophilia and a remarkable basophilia. At necropsy, a bilateral conjunctivitis was diagnosed and a tumorous mass was found in the left submandibular region. Histologically, the tumor was composed of round to polygonal cells with pale cytoplasm, containing abundant predominantly basophilic granules. The intracytoplasmatic granules stained metachromatically with Toluidine blue and immunostained positively with serotonin. Numerous eosinophils were scattered throughout the tumor and were also present in other organs. Cells with round, oval, or indented nuclei and abundant cytoplasm, containing pronounced eosinophilic granules, were found in spleen and bone marrow. They turned out to be immature stages of eosinophilic granulocytes. Characteristics of the present tumor are compared with observations on mast cell tumors in other species.
Two-Year and Lifetime Toxicity and Carcinogenicity Studies of Ozone in B6C3F1 Mice
Authors: Herbert Ron A. , Hailey James R. , Grumbein Sondra , Chou Billy J. , Sills Robert C. , Haseman Joseph K. , Goehl Thomas , Miller Rodney A. , Roycroft Joseph H. , Boorman Gary A.
Published: April 2009

To evaluate the toxicity and carcinogenic potential of long-term exposure to ozone, B6C3F1 mice were exposed by whole-body inhalation to 0, 0.12, 0.5, or 1.0 ppm and 0, 0.5, or 1.0 ppm ozone for 24 or 30 mo (lifetime), respectively. The incidence of alveolar/ bronchiolar adenomas and carcinomas (combined) increased (p < 0.05) in female mice exposed to 1.0 ppm for 24 or 30 mo and marginally increased (p > 0.05) in male mice exposed to concentrations of 0.5 or 1.0 ppm. An increased incidence of nonneoplastic lesions were observed in the nasal cavities and in the centriacinar region of the lung of mice exposed to 0.5 or 1.0 ppm for 24 and 30 mo. Nasal cavity lesions were mild and included hyaline degeneration, hyperplasia, squamous metaplasia, fibrosis and suppurative inflammation of the transitional and respiratory epithelium of the lateral wall, and atrophy of the olfactory epithelium. Lung lesions included replacement of the epithelium of the alveolar ducts and adjacent alveolar septa with epithelium similar to that normally found in terminal bronchioles (metaplasia) and associated alveolar histiocytosis. Based on the results of these studies, we conclude that inhalation exposure of B6C3F1 mice to ozone for 24 or 30 mo (a) is carcinogenic in female B6C3F1 mice exposed to 1.0 ppm of ozone based on an increased incidence of alveolar/bronchiolar adenoma or carcinoma and (b) results in mild, site-specific, nonneoplastic lesions in the nasal cavity and centriacinar lung of male and female mice exposed to 0.5 or 1.0 ppm of ozone for 2 yrs, which persist with continued exposure to 30 mo. It is uncertain whether or not the marginal increase (p > 0.05) of alveolar/bronchiolar neoplasms in male B6C3F1 mice resulted from exposure to ozone.
Examination of Lesions in the Urinary Bladder and Kidney of Dogs Induced by Nefiracetam, a New Nootropic Agent
Authors: Kashida Yoko , Yoshida Mitsuyosi , Ish Yoshikazu , Nomura Mamoru , Kato Michiyuki
Published: April 2009

Toxic lesions induced by nefiracetam, a nootropic drug, in the urinary bladder and kidney were examined by repeated oral administration of 300 mg/kg/day for 1, 2, 3, 4, or 11 wk to male and female beagle dogs. Each dog was sacrificed after each treatment period, and urinalysis and serum biochemistry were performed for surviving dogs at several time points. One male and 2 females died during week 10 or 11. Degeneration and desquamation of epithelial cells and edema and hemorrhage in the lamina propria were observed in the urinary bladder after 1 wk of treatment. These changes became severe as time progressed and were reflected in the clinical abnormalities of hematuria and increased protein excretion in urine. However, epithelial regeneration and hyperplasia were seen thereafter, and almost no change was seen in the urinary bladder after treatment for 11 wk. Instead of recovery as in the urinary bladder, the kidney showed epithelial degeneration and hyperplasia in the papilla and collecting duct and interstitial congestion and hemorrhage after treatment for 11 wk. Extensive hemorrhage and papillary necrosis were seen in animals that died during week 10 or 11 of dosing. These kidney changes were associated with increased urinary volume and decreased osmotic pressure. The lesions are thought to have a common etiopathogenesis and to be initiated by the epithelial damage with a time lag between expression of injury in the urinary bladder and the kidney.
Histopathological Evaluation of Liver, Pancreas, Spleen, and Heart from Iron-Overloaded Sprague-Dawley Rats*1,2
Authors: Whittaker Paul , Hines Fred A. , Robl Martin G. , Dunkel Virginia C.
Published: April 2009

The effects of increasing dietary levels of Fe on the histopathology of liver, pancreas, spleen, and heart were examined in a rat model for iron overload. Sprague-Dawley rats were fed diets containing 35, 350, 3,500, or 20,000 μg Fe/g, and, after 12 wk, there was a direct correlation between increased liver nonheme Fe and lipid peroxidation measured by the lipid-conjugated diene assay. Histopathological examination of tissues revealed the following: (a) hepatocellular hemosiderosis in all groups of rats, with a dose-related accumulation of cytoplasmic Fe-positive material predominantly in hepatocytes located in the periportal region (Zone 1), (b) myocardial degeneration and necrosis (cardiomyopathy) with hemosiderin in interstitial macrophages or in myocardial fibers of animals with heart damage, (c) splenic lymphoid atrophy affecting the marginal zone of the white pulp and hemosiderin deposition in the sinusoidal macrophages, and (d) pancreatic atrophy with loss of both the endocrine and exocrine pancreatic tissue in those animals receiving 3,500 and 20,000 μg Fe/g of diet. The toxic effects of Fe overload in this rat model include cellular apoptosis or necrosis in heart, spleen, and pancreas and, when coupled with the findings on lipid peroxidation, suggests that oxidative stress is involved in the pathogenesis of the lesions.
The Experimental Antipsychotic Agent 1192U90 Targets Tapetum Lucidum in Canine Eyes
Authors: Dillberger John E. , Peiffer Robert L. , Dykstra Michael J. , O'Mara Michael , Patel Dipak K.
Published: April 2009

To assess the potential adverse effects in people of the antipsychotic agent 1192U90, we dosed mice, rats, beagles, and cynomolgus monkeys for up to 3 mo. In dogs, but not the other species, 1192U90 caused ocular changes detectable ophthalmoscopically as loss of tapetal reflectivity, altered tapetal color, and the appearance of black pigmentation on the tapetal fundus. Eyes from affected dogs had atrophic tapeta lucidum due to cell loss. Rodlets in remaining tapetal cells were separated by electron-lucent spaces or finely granular material, varied in size and shape, and often contained irregularly shaped electron-dense inclusions. Nontapetal ocular structures were unaffected. Because 1192U90 caused no ocular changes in nontapetal species, we hypothesized that it targeted only tapetum lucidum and spared other ocular structures. We tried to test this hypothesis by dosing congenitally atapetal dogs; however, although these dogs were ophthalmoscopically "atapetal," they had scattered tapetal cells visible by electron microscopy, and these tapetal cells had ultrastructural changes indistinguishable from those that occurred in treated normal-eyed dogs. Tapetal degeneration caused by 1192U90 resembled that described in hereditary tapetal degeneration in beagles. That 1192U90 caused no ocular changes in nontapetal species suggests that the ocular changes in dogs do not imply a risk for humans, whose eyes also lack a tapetum lucidum.
Changes in Rat Heart Histomorphometry Due to Two-Week Dietary Restriction
Authors: Burkhardt J.E. , Ochoa R. , Kowsz K.P. , Levin S. , Jakowski A.B.
Published: April 2009

In preclinical safety studies in which the administration of a test compound causes reductions in food consumption, body weights, and organ weights, it may be difficult to differentiate direct compound-induced effects on organ weights from those simply due to reduced nutrition. To address this problem in reference to the heart, hearts were obtained from rats that were known to have had reductions in body weights and absolute heart weights as a result of feed restriction. Rats (40/sex) were divided into 4 groups (10/ sex) and given quantities of ad libitum diet for 2 wk as follows: Group 1, 100%; Group 2, 75%; Group 3, 50%; and Group 4, 25%. Routine histologic evaluation was performed on longitudinal sections of paraffin-embedded hearts stained with hematoxylin and eosin. Computer-assisted image analysis was conducted on left ventricular free-wall of picrosirius red-stained sections for histomorphometric evaluation of ratio of cross-sectional area occupied by myofibers versus interstitium and for quantification of myofiber width. No differences were detected histologically among groups, and no difference in the mean myofiber : interstitium ratio was detected between Groups 1 (9.1) and 4 (9.5). Mean values for myofiber width ranged from 24.6 μm for Group 1 to 17.3 μm for Group 4. Two-way ANOVA revealed a strong effect of dietary restriction on reduction of myofiber width but no consistent gender effect. The significant dietary effects occurred in Groups 3 and 4 compared to corresponding controls. The present authors speculate that, if reductions in feed intake were <50% in short-term preclinical studies, any reductions in myofiber width could imply a primary test article effect. Conversely, if reductions in feed intake were ≥50% in such studies, reductions in myofiber width could be caused either solely by inadequate nutrition or by combined effects of nutrition and test article.
Food and Drug Administration Workshop on Indirect Mechanisms of Carcinogenesis
Authors: Poirier Lionel A.
Published: April 2009

A workshop sponsored by the Food and Drug Administration (FDA) was held on March 4-5, 1996, at the Lister Hill Auditorium of the National Institutes of Health (NIH) Campus in Bethesda, Maryland. The workshop considered both the scientific aspects and the regulatory implications of indirect-acting carcinogens. A wide variety of agents and of prospective mechanisms was discussed. The organizing committee for the workshop consisted of Drs. James Farrelly and Joseph DeGeorge of the Center for Drug Evaluation and Research (CDER), Ronald J. Lorentzen and Sidney Green of the Center for Food Safety and Applied Nutrition (CFSAN), Martin D. Green of the Center for Biologics, Evaluation and Research (CBER), C. Darnell Jackson and Lionel A. Poirier of the National Center for Toxicological Research (NCTR), Rosalie K. Elespuru of the Center for Devices and Radiological Health (CDRH), and David G. Longfellow of the National Cancer Institute (NCI). Following an introduction by Dr. Poirier, who provided a description of indirect carcinogens, the major talks were grouped into three formal sessions: indirect-acting compounds and agents of FDA interest, biological and biochemical endpoints commonly seen with indirect agents, and specific problems associated with the indirect-acting compounds. A panel discussion followed and the concluding remarks were made by Dr. Bernard A. Schwetz, Associate Commissioner for Science, FDA.
Aberrant Crypt Foci in the Colonic Mucosa of Rats Treated with a Genotoxic and Nongenotoxic Colon Carcinogen
Authors: Whiteley Laurence O. , Hudson Leon , Pretlow Theresa P.
Published: April 2009

Aberrant crypt foci (ACFs) are putative preneoplastic lesions in the colonic mucosa identified by examining methylene blue-stained whole mounts of colon. ACFs have been previously described in rats treated with genotoxic colon carcinogens. This study determined whether or not a nongenotoxic colon carcinogen could induce ACFs and compared the morphology of these ACFs with those induced by a genotoxic colon carcinogen. Six-wk-old Fischer-344 rats were administered dextran sulfate (DSS, nongenotoxin) in the drinking water or azoxymethane (AOM, genotoxin) by single subcutaneous injection. Rats were sacrificed at 9 and 14 wk after study initiation. Colons were fixed and stained with methylene blue, and the mucosal surface of transilluminated whole mounts was examined with a microscope. The number of ACFs and number of crypts per focus (multiplicity) were recorded. Representative ACFs were processed into glycol methacrylate for hexosaminidase enzyme histochemistry and sections of the remaining colon containing ACFs were embedded in paraffin for morphologic evaluation. In whole mounts, ACFs from AOM- and DSS-treated rats had elongated slit-to-oval-shaped lumens surrounded by a thickened and intensely stained epithelium. DSS-induced aberrant crypts differed from those induced by AOM in that they were frequently larger, tended not to form discrete foci circumscribed by normal crypts, and were located adjacent to ulcers. Total ACFs and large foci (4 or more crypts/focus) were significantly more numerous in AOM-treated rats at both time points. Histologically, DSS-induced ACFs had segmental to diffuse loss of hexosaminidase activity, mucin depletion to increased prominence of goblet cells, and marked distortion of crypt architecture. AOM-induced ACFs had diffuse loss of hexosaminidase activity, variable depletion of mucin, and less distortion of crypt architecture. Variable degrees of epithelial dysplasia were seen in ACFs with both carcinogens, but dysplasia was more severe in DSS-induced ACFs. Colonic mucosal neoplasms were induced by both carcinogens. In subchronic studies, the ACF assay may be a useful method to improve the identification and characterization of xenobiotic-induced changes in colonic mucosal crypts.
A Critical Appraisal of the Value of the Mouse Cancer Bioassay in Safety Assessment
Authors: Alden Carl L. , Smith Peter F. , Piper Charles E. , Brej Leszek
Published: April 2009

Substantial progress in understanding nongenotoxic or secondary mechanisms of tumorigenesis has been made over the past decade. However, the methods used in regulated studies for assessment of carcinogenic potential in chemicals in development have not evolved significantly. Based on the experience of over 30 yr of testing and the societal need to control costs, reevaluation of standard cancer rodent bioassay protocols is being done. Expert consensus after evaluating the results of full-scale rodent bioassays of both sexes in 2 species is that a reduced protocol is acceptable. After review of relevant data, it is our opinion that cancer hazard assessment in male and female rats only would be sufficient and that, in the future, mouse bioassays will not add significant value on a routine basis. We are unable to find an example of a mouse tumorigenic finding that predicts a confirmed or probable human response with negative findings in a rat bioassay. The savings realized by eliminating mouse testing from routine protocols would be substantial and better spent in expanding short-term studies to add to our understanding of chemical carcinogenesis.
Rationale for the Use of Dietary Control in Toxicity Studies—B6C3F1 Mouse
Authors: Turturro Angelo , Duffy Peter , Hart Ronald , Allaben William T.
Published: April 2009

Significant variability in critical study parameters such as tumor incidences and survival, increasing tumor incidence and decreasing survival in common toxicity test models, and agent-induced changes in body weight (BW) and BW distribution all generate concern about the reproducibility, consistency, and equity of chronic toxicity tests used in regulation. These concerns have led to suggestions to control BW in chronic tests by the modulation of dietary intake without inducing malnutrition [dietary control (DC)] thereby minimizing tumor and survival variability both between and within studies. Evaluating the reports of the best controlled set of chronic experiments, the National Toxicology Program bioassay series, from studies initiated from 1981 to 1990, there is an increase in tumor incidence, especially liver tumors, with a consistent increase in BW. The studies are classified as to whether normal or aberrant BW growth curves occur. When the studies with normal growth curves are considered, the variance in the BW at 12 mo on test (BW12) can account for over 50% of the variance in liver tumor incidence. Additional stratification by study type, which alter tumor prevalences, as well as appreciation of housing effects [group housing decreases survival (in male mice) and induces tumors in males and females when compared to individual housing], further increase the strength of the correlations, accounting for up to 90% of the variance seen in tumor incidences. These updated analyses further support the hypothesis that it is the BW variation that is resulting in much of the variability seen in tumor incidences and refine the suggestions for the BW curves used as the desired targets for DC.
FDA Points-to-Consider Documents: The Need for Dietary Control for the Reduction of Experimental Variability within Animal Assays and the Use of Dietary Restriction to Achieve Dietary Control
Authors: Allaben William T. , Turturro Angelo , Leakey Julian E.A. , Seng John E. , Hart Ronald W.
Published: April 2009

Standard protocols for conducting chronic toxicity and carcinogenicity studies have been refined over the years to carefully control for many variables. Nevertheless, over the last 2 decades, there has been a steady increase in variability, a decrease in survival, an increase in tumor incidence rates, and an increase in the average body weight of control animals among the various rodent species and strains used for toxicity testing. These observations have prompted an evaluation of chronic study designs to determine what factor(s) may be responsible for such confounding changes. Ad libitum feeding and the selection of successful breeders with rapid offspring growth is believed to be at least partially responsible for the heavier, obese rodents with which many laboratories are coping today. As a result of these changes, some studies used for the evaluation of safety have been deemed inconclusive or inadequate for regulatory purposes and either additional supportive studies have been requested and/or studies per se have been repeated. Research on the molecular mechanisms of caloric restriction and agent-induced toxicity at the Food and Drug Administration (FDA) National Center for Toxicological Research stimulated the first international conference on the biological effects of dietary restriction in 1989; this was followed in 1993 by an FDA workshop exploring the utility of dietary restriction in controlling reduced survival in chronic tests and an international conference in 1994 exploring the implications for the regulatory community of using dietary restriction in toxicity and carcinogenicity studies used in support of a sponsor's submission or in risk assessments. The outcome of that conference was the FDA's commitment to develop Points-to-Consider documents that address the issue of dietary control in chronic toxicity and carcinogenicity studies.
Chronic Granulomatous Pneumonia and Lymphocytic Responses Induced by Inhaled Beryllium Metal in A/J and C3H/HeJ Mice
Authors: Nikula Kristen J. , Swafford Deborah S. , Hoover Mark D. , Tohulka Mark D. , Finch Gregory L.
Published: April 2009

Inhalation of beryllium (Be) has been associated with 2 syndromes: an acute chemical pneumonitis and a granulomatous lung disease known as chronic beryllium disease (CBD). Key to the pathogenesis of CBD is a delayed-type hypersensitivity reaction, in which Be most likely functions as a hapten and acts as a Class II-restricted antigen, stimulating local proliferation and accumulation in the lung of Be-specific CD4+ T cells. The purpose of this study was to establish a mouse model of CBD using the inhalation route of exposure. A/J (H-2a haplotype) and C3H/HeJ (H-2k) mice were exposed once for 90 min in nose-only exposure tubes to aerosols of Be metal. Six mo later, lung histopathologic responses were assessed. Further analyses defined the phenotypic profile of lymphocytes in pulmonary lesions and evaluated proliferation of lymphocytes in situ and in response to Be in vitro. Responses were similar in both strains of mice. The lungs of all Be-exposed mice had interstitial compact aggregates of lymphocytes, and granulomatous pneumonia characterized by vacuolated macrophages and giant cells in alveoli, neutrophils in alveoli and alveolar septa, multifocal interstitial granulomas, and interstitial infiltrates of lymphocytes, plasma cells, monocytes, and macrophages. Most Be-exposed mice had minimal to mild interstitial fibrosis. The majority of lymphocytes in interstitial infiltrates and in microgranulomas were CD4+ T cells. Interstitial compact aggregates of lymphocytes contained B cells centrally and CD4+ cells peripherally. Lymphocyte labeling indices, used to assess proliferation in situ, were significantly greater within microgranulomas compared to compact lymphocytic aggregates. Lymphocyte stimulation indices in response to BeSO4 in vitro were not positive in blood, spleen, or tracheobronchial lymph node samples. Be-specific immune responses and nonspecific inflammatory responses to toxic and foreign-body properties of Be may have contributed to the histopathology in both strains of mice. The interstitial mononuclear cell infiltrates, presence of microgranulomas, multinucleated foreign-body and Langhans' giant cells, interstitial fibrosis, and CD4+ T-cell predominance with local proliferation are features similar to CBD in humans. The chronic lung disease induced in these mice by inhaled Be can be used to investigate the importance of variables such as dose, exposure pattern, and physicochemical form of Be in producing this disease.
Food and Drug Administration Risk Assessment—Process and Toxicologic Pathology
Authors: Moch Ronald W. , Dua Prem N. , Hines Fred A.
Published: April 2009

A general outline of the risk assessment process at the Center for Food Safety and Applied Nutrition (CFSAN) of the Food and Drug Administration based on the toxicologic evaluation of data is described. Examples of recent pathology evaluations are presented to illustrate primarily the pathology review process at the CFSAN. These examples include the review of data from rodent studies from proposed indirect food additives and data from dog studies submitted in support of an investigational new drug, a short-acting opioid, proposed as an anesthetic in humans.
Concepts of Cell Death and Application to Carcinogenesis
Authors: Schulte-Hermann Rolf , Bursch Wilfried , Grasl-Kraupp Bettina , Marian Brigitte , Török Ladislaus , Kahl-Rainer Patrizia , Ellinger Adolf
Published: April 2009

The occurrence of cell death as a physiologic event in multicellular organisms has been known for more than 150 yr. In 1972, the term apoptosis was introduced on morphological grounds. The hypothesis that all kinds of cell death can be categorized as either "apoptotic" or "necrotic" is not generally confirmed. Cells seem to use different pathways for suicide, as reflected by different morphology: condensation-prominent, Type I or apoptosis; autophagy-prominent, Type II; and so forth. Type II cell death was found in mammary tissue and mammary tumor cells and in a variety of other organs. For unequivocal identification of the various types of cell death, morphological, biochemical, and functional criteria may be used in combination. During tumor development in various organs of animals and humans, not only rates of cell proliferation but also rates of cell death may increase with increasing malignancy. Morphological and functional criteria (antipromotion, withdrawal of survival factors) indicate that cell death in tumors frequently is of an active nature.
Review Article: Evaluation of Testicular Toxicity in Safety Evaluation Studies: The Appropriate Use of Spermatogenic Staging
Authors: Creasy Dianne M.
Published: April 2009

Toxicology of the male reproductive system has received increased interest in recent years partly fuelled by the growing reports of falling sperm counts and rising reproductive disorders in the human population. Recently revised regulatory guidelines for the safety assessment of pharmaceuticals and chemicals on reproduction and fertility have emphasized the importance of detailed histopathological examination of the testes as a sensitive method for detecting disturbances in spermatogenesis. Unfortunately this has been accompanied by a general confusion regarding a practical approach to undertaking such a detailed examination, particularly in respect to the use of spermatogenic or tubular staging to identify subtle disturbances in spermatogenesis. The ability to identify tubular stages of the spermatogenic cycle in sections of testis plus a good understanding of the spermatogenic process and its dynamics are essential in order to carry out a sensitive examination of testicular histopathology and to interpret the changes seen. A rational approach is required initially to detect and subsequently to characterize toxic effects to the male reproductive system. It is important that a distinction is made between these two objectives since different study designs are required and different methodology may be employed to produce the type of information or data required.
Increased Nuclear Ploidy, Not Cell Proliferation, Is Sustained in the Peroxisome Proliferator-Treated Rat Liver
Authors: Lalwani Narendra D. , Dethloff Lloyd A. , Haskins Jeffrey R. , Robertson Donald G. , De La Iglesia Felix A.
Published: April 2009

Peroxisome proliferators are believed to induce liver tumors in rodents due to sustained increase in cell proliferation and oxidative stress resulting from the induction of peroxisomal enzymes. The objective of this study was to conduct a sequential analysis of the early changes in cell-cycle kinetics and the dynamics of rat liver DNA synthesis after treatment with a peroxisome proliferator. Immunofluorescent detection of proliferating cell nuclear antigen (PCNA) and bromodeoxyuridine (BrdU) incorporation into DNA during S phase were used to assess rat hepatocyte proliferation in vivo during dietary administration of Wy-14,643, a known peroxisome proliferator and hepatocarcinogen in rodents. Rats were placed on a diet containing 0.1% Wy-14,643 and implanted subcutaneously with 5-bromo-2'-deoxyuridine containing osmotic pumps 4 days prior to being sacrificed on days 4, 11, and 25 of treatment. Isolated liver nuclei labeled with fluorscein isothiocyanate (FITC)-anti-BrdU/PI and FITC-anti-PCNA/PI were analyzed for S-phase kinetics using flow cytometry. Morphometric analysis was performed to evaluate nuclear and cell size and enumeration of BrdU labeled cells, binucleated hepatocytes, and mitotic index. The BrdU labeling index increased 2-fold in livers of Wy-14,643-treated rats at day 4, but distribution of cells in G1, S phase, and G 2-M did not differ significantly from controls. PCNA-positive cells decreased from 36% on day 4 to 17% on day 25, whereas the percentage of PCNA-positive cells in controls increased 2-fold from day 4 to day 11 and remained unchanged up to day 25. The differences in the number of PCNA-positive nuclei between control and Wy-14,643-treated groups were statistically significant only on day 4. Binucleated hepatocytes, determined by morphometric analysis, increased slightly on day 25 in treated rats parallel to an increase in the percentage of cells in G2-M phase. Significant shifts were noted in nuclear diameter and nuclear area after 11 and 25 days of treatment with Wy-14,643. Hepatic cell populations with nuclei >9 μm diameter and nuclear area >64 μm2 increased in Wy-14,643-fed rats during the treatment period compared with the control, indicating hepatic karyomegaly and hyperploidy, whereas percentage of distribution of nuclei based on diameter and area remained consistently unchanged in control animals from 4 through 25 days of sham treatment. The flow cytometric and morphometric analysis indicated an initial wave of DNA synthesis in response to Wy-14,643. The hepatomegaly was sustained over the treatment period accompanied by increase in ploidy with a significant shift toward hyperploidic hepatocytes. The increase in DNA content was almost entirely accounted for by the overall polyploidy increase rather than by an absolute increase in cells.
Oral Squamous Cell Carcinoma in Ad Libitum-Fed and Food-Restricted Brown-Norway Rats
Authors: Thurman J. Dale , Greenman David L. , Kodell Ralph L. , Turturro Angelo
Published: April 2009

A high incidence of oral squamous cell carcinoma was present in male and female Brown-Norway rats fed ad libitum or food-restricted dietary formulations. One hundred eighty-nine rats were examined from 4 dietary treatment groups: male ad libitum, male food-restricted, female ad libitum, and female food-restricted. The ad libitum treatment groups for both males and females had significantly more cases of oral squamous cell carcinoma than cohort food-restricted groups. In ad libitum rats, 10 of 47 (21%) males and 15 of 47 (32%) females had oral squamous cell carcinoma, whereas only 4 of 47 (9%) males and 5 of 48 (10%) females in the food-restricted groups were similarly affected. The food-restricted rats lived significantly longer than ad libitum cohorts, so the higher incidence of squamous cell carcinoma was not dependent on extended lifespans. In addition to the dietary influence, a significant difference in oral squamous cell carcinoma incidence occurred between various familial lines. Family lines having representatives in both ad libitum and food-restricted groups had lower oral squamous cell carcinoma incidences in the food-restricted group whether comparing affected litters or individuals. Results suggest that the incidence of oral squamous cell carcinoma in our colony of Brown-Norway rats can be influenced by both the dietary treatment group and genetic predilection within certain pedigrees.
Dose-Dependent Amplification by L-Ascorbic Acid of NaHCO3 Promotion of Rat Urinary Bladder Carcinogenesis
Authors: Iwata Hiroyuki , Yamamoto Shinji , Yano Yoshihisa , Ohtani Shuzo , Fukushima Shoji
Published: April 2009

The dose dependence of L-ascorbic acid (AsA) copromotion of urinary bladder carcinogenesis with continuous concomitant administration of NaHCO3 was investigated. In the first experiment, 83 male F344 rats were all given 0.05% N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN) for 4 wk and then divided into 5 groups, which received basal diet (Oriental MF) containing AsA at 0, 1, 2, 3.5, or 5% plus 1.5% NaHCO3 for 32 wk. Relative urinary bladder weights in the 5% AsA group were significantly increased as compared to the 0 or 1% group values due to the development of tumors. Both the incidence and number of microscopic urinary bladder lesions (tumors and preneoplastic lesions) showed dose-dependent increases. Furthermore, the sizes of the urinary bladder tumors (carcinomas and papillomas) were significantly increased with the highest dose. 5-bromo-2'-deoxyuridine labeling indices showed slightly increased proliferation in preneoplastic lesions of the urinary bladder epithelium with 5% AsA treatment. In a separate experiment, scanning electron microscopic observation revealed that administration of 5% AsA plus 1.5% NaHCO3 for 8 wk, without BBN, altered the urinary bladder surface. Elevation of urinary bladder epithelium AsA content, as well as urinary AsA, was also noted. Ornithine decarboxylase (ODC) activity and ODC messenger RNA levels in urinary bladder epithelium of rats treated with 1.5% NaHCO3 plus 5% AsA for 8 wk showed no statistically significant differences as compared to the control group. The results indicate that AsA amplifies the rat urinary bladder carcinogenesis promotion activity of NaHCO 3 and that its intensity of action depends on the dose, particularly at high dose.
Uranyl Nitrate—Induced Proximal Tubule Alterations in Rabbits: A Quantitative Analysis
Authors: McDonald-Taylor C. Kim , Singh Amreek , Gilman Andy
Published: April 2009

Naturally occurring uranium in drinking water is a significant health concern in several areas of North America. Because the kidney is a known target organ to examine the effects of uranium or its compounds, the objective of this study was to determine whether kidney repair occurs after exposure to, and withdrawal of, uranyl nitrate (UN). This work, part of a larger study to establish safe levels of uranium in drinking water supplies, examined the ultrastructural changes in proximal tubule cells of New Zealand white rabbits following subchronic exposure to UN in water and for 91 days after exposure ended. The rabbit was chosen as the experimental animal because of its high sensitivity to uranium. Animals were exposed to 24 or 600 mg UN per liter (UN/L) in drinking water for 91 days, with no recovery or recovery periods of 45 or 91 days. Ultrastructural changes, quantified by a stereological image anlysis system based on point counting, were observed in renal proximal tubules (PTs). Each electron micrograph was statistically considered an experimental unit. The severity of lesions was directly proportional to the dose. Animals exposed to 600 mg UN/L had the most severe lesions; nevertheless, alterations were remarkable in animals exposed to the low dose. At both recovery periods, the lesions were significantly more severe than those in animals of the no-recovery group, which may result from the kidney's ability to store uranium. The PT cells had increased lysosomal and vacuolar mass as well as variations in mitochondrial mass. In addition, there was epithelial cell degeneration with a focal loss of brush borders, thickening and splitting of tubular basement membrane, and occasionally cell necrosis. Interstitial fibrosis of the renal cortex persisted as the recovery period increased in the animals of UN-dosed groups. Alterations may be due to disturbed fluid transport across the PT and other cells and decreased cell respiration resulting from damaged cell constituents. Cell damage caused by UN in drinking water persisted throughout the 91-day recovery period. By eventually determining the no observable effect level for the kidney by UN, this study may assist in devising a model to ascertain the safe levels of uranium in water.
Phenolphthalein Induces Thymic Lymphomas Accompanied by Loss of the p53 Wild Type Allele in Heterozygous p53-Deficient (±) Mice
Authors: Dunnick June K. , Hardisty Jerry F. , Herbert Ronald A. , Seely John C. , Furedi-Machacek E. Marianna , Foley Julie F. , Lacks Gregory D. , Stasiewicz Stanley , French John E.
Published: April 2009

Epidemiology studies have indicated that many human cancers are influenced by environmental factors. Genetically altered mouse model systems offer us the opportunity to study the interaction of chemicals with genetic predisposition to cancer. Using the heterozygous p53-deficient (±) mouse, an animal model carrying one wild type p53 gene and one p53 null allele, we studied the effects of phenolphthalein on tumor induction and p53 gene alterations. Earlier studies showed that phenolphthalein caused carcinogenic effects in Fisher 344 rats and B6C3F, mice after a 2-yr dosing period (Dunnick and Hailey, Cancer Res. 56: 4922-4926, 1996). The p53 (±) mice received phenolphthalein in the feed at concentrations of 200, 375, 750, 3,000, or 12,000 ppm (approximately 43, 84, 174, 689, or 2,375 mg/kg body weight/day or 129, 252, 522, 2,867, or 7,128 mg/m2body surface area/day) for up to 6 mo. A target organ cancer site that accumulated p53 protein in the B6C3F, mouse (i.e., thymic lymphoma) was also a target site for cancer in the p53 (±) mouse. In the p53 (±) mouse, treatment-related atypical hyperplasia and malignant lymphoma of thymic origin were seen in the control and dosed groups at a combined incidence of 0, 5, 5, 25, 100, and 95%, respectively. Twenty-one of the thymic lymphomas were examined for p53 gene changes, and all showed loss of the p53 wild type allele. Chemical-induced ovarian tumors in the B6C3F, mouse showed no evidence for p53 protein accumulation and did not occur in the p53 (±) mouse. The p53-deficient (±) mouse model responded to phenolphthalein treatment with a carcinogenic response in the thymus after only 4 mo of dosing. This carcinogenic response took 2 yr to develop in the conventional B6C3F, mouse bioassay. The p53-deficient (±) mouse is an important model for identifying a carcinogenic response after short-term (<6 mo) exposures. Our studies show that exposure to phenolphthalein combined with a genetic predisposition to cancer can potentiate the carcinogenic process and cause p53 gene alterations, a gene alteration found in many human cancers.
Giant Cell Tumor of Bone in an Aged Fischer 344 Rat
Authors: Imai Toshio , Hibino Nobuhiro , Hayakawa Kazuhiro , Nakanowatari Junichi , Fukuta Taneo , Hosokawa Satoru , Sagami Fumio
Published: April 2009

A giant cell tumor (GCT) was detected on the distal end of the femur in a 98-wk-old male Fischer 344 rat. The yellowish white mass had expanded, compressing adjacent muscle tissues. The tumor had an osteolytic and relatively homogeneous appearance and was composed of multinuclear giant cells scattered in a mass of mononuclear stromal cells. No osteoid tissue formation was observed. The tumor cells were strongly immunoreactive for ED-1 and some were also positive for α-smooth muscle actin, suggesting that the tumor originated from the monocyte/macrophage lineage showing myofibroblastic differentiation. This is the first report concerning spontaneous GCT of bone in a rat.
Antisaccade and smooth pursuit eye movements in healthy subjects receiving sertraline and lorazepam
Authors: Green Jonathan F. , King David J. , Trimble Karen M.
Published: April 2009

Patients suffering from some psychiatric and neurological disorders demonstrate abnormally high levels of saccadic distractibility when carrying out the antisaccade task. This has been particularly thoroughly demonstrated in patients with schizophrenia. A large body of evidence has been accumulated from studies of patients which suggests that such eye movement abnormalities may arise from frontal lobe dysfunction. The psychopharmacology of saccadic distractibility is less well understood, but is relevant both to interpreting patient studies and to establishing the neurological basis of their findings. Twenty healthy subjects received lorazepam 0.5 mg, 1 mg and 2 mg, sertraline 50 mg and placebo in a balanced, repeated measures study design. Antisaccade, no-saccade, visually guided saccade and smooth pursuit tasks were carried out and the effects of practice and drugs measured. Lorazepam increased direction errors in the antisaccade and no-saccade tasks in a dose-dependent manner. Sertraline had no effect on these measures. Correlation showed a statistically significant, but rather weak, association between direction errors and smooth pursuit measures. Practice was shown to have a powerful effect on antisaccade direction errors. This study supports our previous work by confirming that lorazepam reliably worsens saccadic distractibility, in contrast to other psychotropic drugs such as sertraline and chlorpromazine. Our results also suggest that other studies in this field, particularly those using parallel groups design, should take account of practice effects.
Mania in a patient receiving testosterone replacement post-orchidectomy taking St John’s wort and sertraline
Authors: Barbenel D. M. , Yusufi B. , O’Shea D. , Bench C. J.
Published: April 2009

We describe the case of a patient who developed depression following bilateral orchidectomy for cryptorchidism. He was treated with a conventional selective serotonin reuptake inhibitor antidepressant, but continued to take St John’s wort (hypericum) against medical advice. He subsequently developed a manic episode. We discuss postulated modes of action of St John’s wort and the possible aetiological importance of testosterone replacement and abnormal gonadotrophin levels in this case.
The acute effects of amisulpride (50 mg and 200 mg) and haloperidol (2 mg) on cognitive function in healthy elderly volunteers
Authors: Legangneux E. , McEwen J. , Wesnes K. A. , Bergougnan L. , Miget N. , Canal M. , L'Heritier C. , Pinquier J. L. , Rosenzweig P.
Published: April 2009

In this double-blind, placebo controlled, four-way cross-over trial in 16 healthy elderly volunteers, the acute effects of haloperidol 2 mg, amisulpride 50 mg and 200 mg, were assessed on a range of tests of cognitive function. On each study day, cognitive performance was assessed prior to dosing and at 2, 4, 6, 9, 12 and 24 h after dosing with the following tests from the Cognitive Drug Research computerized assessment system: simple reaction time, digit vigilance task, choice reaction time, visual tracking, Critical Flicker Fusion, body sway, numeric working memory, immediate and delayed word recall, word recognition and self-ratings of mood and alertness. Haloperidol showed a general tendency to impair performance, and although this did not reach significance compared to placebo, for two tasks there were significant impairments with haloperidol compared to amisulpride. Amisulpride 50 mg and 200 mg, was not associated with impairment. In fact, there was some suggestion of improvement over placebo on three measures. The timings of assessment were appropriate for the study compounds. Furthermore, in a recent study in which a smaller number of elderly volunteers was tested on the same cognitive assessment system, a clear profile of acute impairments of haloperidol 3 mg, was identified. This indicates that haloperidol 2 mg, is not a sufficient dose to affect cognitive function in the elderly, supporting the general absence of effects with this dose in the young. Thus, the general absence of cognitive impairments with amisulpride at the doses used in this study suggests that this compound does not impair cognitive function in the elderly.