bluuebunny/crossref_metadata_2025 huggingface dataset:
A Mechanistic Study of Ovarian Carcinogenesis Induced by Nitrofurazone Using rasH2 Mice
Authors: Takegawa Kiyoshi , Mitsumori Kunitoshi , Yasuhara Kazuo , Moriyasu Matsuko , Sakamori Masamitsu , Onodera Hiroshi , Hirose Masao , Nomura Tatsuji
Published: February 2008

In order to clarify whether the ovarian tumors induced in a long-term carcinogenicity study of nitrofurazone (NF) in mice can be also produced in a short-term model using transgenic (Tg) mice carrying the human c-Ha-ras gene (rasH2 mice), the following 3 experiments were performed. In experiment 1, both rasH2 mice and their wild CB6F1 littermates carrying no c-Ha-ras gene (non-Tg mice) that were fed a diet containing 500 to 1,000 ppm NF for 7 weeks demonstrated ovarian atrophy characterized by decreased labeling indices (LIs) for proliferating cell nuclear antigen (PCNA) in granulosa cells. In experiment 2, increased numbers of atretic follicles and decreased PCNA LIs in granulosa cells were recognized in rasH2 mice given diets containing 250 or 500 ppm NF for 26 weeks, but no tumor induction was grossly observed. In experiment 3, similar ovarian atrophy was observed in association with increased serum luteinizing hormone (LH) levels in both rasH2 and non-Tg mice given diet containing 1,000 ppm NF for 11 days. These results indicate that long-term NF treatment induces ovarian tumors in mice, possibly by continuous stimulation with gonadotropins such as LH via a negative-feedback phenomenon secondary to ovarian atrophy (as the tumor-induction mechanism), although we could not completely rule out a genotoxic mechanism.
Evaluation of Plasma von Willebrand Factor as a Biomarker for Acute Arterial Damage in Rats
Authors: Newsholme Stephen J. , Thudium Douglas T. , Gossett Kent A. , Watson Erica S. , Schwartz Lester W.
Published: February 2008

Plasma von Willebrand factor (vWF) was evaluated as a potential biomarker of acute arterial damage in rats after a vasotoxic dose of the dopaminergic vasodilator, fenoldopam (FP). Male Sprague-Dawley rats were given FP or isotonic saline by subcutaneous injection, and plasma vWF was measured at 2, 6, and 24 hours after challenge. Mean plasma vWF values increased in FP-treated rats compared to controls at 2 hours (167 vs 122%; p < 0.05) and 6 hours postdose (172 vs 130%; p < 0.01) but were comparable to control values after 24 hours. Mesenteric arterial lesions were observed microscopically in all FP-treated rats 24 hours postdose but were not present in rats at 1, 2, 4, 6, or 8 hours after FP challenge. Further, plasma vWF concentrations increased in saline-treated rats after only the minimal perturbation of repeated venipuncture. These results indicate an early, minimal, and transient release of vWF that precedes the onset of morphologically evident vascular damage. The minimal increases in plasma vWF concentrations were of limited predictive value, may be more reflective of an acute-phase reactant response, and were not considered a reliable biomarker of acute FP-induced arterial damage in the rat.
Ribose Cysteine Protects Against Acetaminophen-Induced Hepatic and Renal Toxicity
Authors: Lucas Angela M. , Hennig Gayle , Dominick Pamela K. , Whiteley Herbert E. , Roberts Jeanette C. , Cohen Steven D.
Published: February 2008

Ribose cysteine (RibCys) is a cysteine prodrug that increases both hepatic and renal glutathione with documented antagonism of acetaminophen (APAP)-induced hepatotoxicity. To determine if RibCys could also protect against APAP-induced kidney damage, mice were injected with APAP (600 mg/kg) or APAP and RibCys (1.0 g/kg) (APAP/RIB) followed by additional RibCys injections 1 and 2 hours later. Mice were euthanatized 10-12 hours after APAP administration, and liver and kidney toxicity were assessed by plasma sorbitol dehydrogenase (SDH) activity and blood urea nitrogen (BUN), respectively, and by histopathology. APAP treatment resulted in elevation of SDH activity and BUN to 2,490 U/ml and 47 mg/dl, respectively. By contrast, SDH and BUN values for APAP/RIB-treated mice were not different from controls, 0 U/ml and 31 mg/dl, respectively. Histopathologic examination revealed moderate to severe hepatic centrilobular necrosis in 9/11 and renal proximal tubular necrosis in 10/11 APAP-treated mice. However, no evidence of hepatic or renal toxicity was noted in any of the 12 APAP/RIB-treated mice. Utilizing the same treatment regimen, APAP covalent binding to hepatic and renal cytosolic proteins was assessed 4 hours after APAP challenge. RibCys cotreatment decreased covalent binding to the 58-kDa acetaminophen-binding protein in both liver and kidney. RibCys decreased both toxicity and covalent binding after APAP administration, and in addition to protecting the liver, this cysteine prodrug can also effectively protect the kidney from APAP-induced injury.
Neoplasia in Zebrafish (Danio rerio) Treated with N-methyl-N'nitro-N-nitrosoguanidine by Three Exposure Routes at ifferent Developmental Stages
Authors: Spitsbergen Jan M. , Tsai Hsi-Wen , Reddy Ashok , Miller Tom , Arbogast Dan , Hendricks Jerry D. , Bailey G.S.
Published: February 2008

We exposed embryos (83 hours postfertilizaton) and fry (3 weeks posthatch) to N-methyl- N'-nitro- N-nitrosoguanidine (MNNG) by immersion in aqueous solutions of 0-10 ppm for 1 hour (embryo) or 0-2 ppm for 24 hours (fry). Zebrafish embryos were microinjected with MNNG at levels of 0 or 96 ng/egg. Diets containing 0-2,000 ppm MNNG were fed to juvenile zebrafish for 3 months beginning at 2 months posthatch. Fish were sampled for histopathologic study at 6-12 months after initiation of carcinogen exposure. Embryos and fry were both quite responsive to MNNG; however, juvenile zebrafish were remarkably refractory to MNNG-induced neoplasia. Principal target organs in zebrafish treated as embryos with MNNG were liver and testis, with hepatocellular adenoma the most prevalent hepatic neoplasm. A variety of mesenchymal neoplasms occurred in zebrafish following embryo exposure to MNNG, including chondroma, hemangioma, hemangiosarcoma, leiomyosarcoma, and rhabdomyosarcoma. Testis and blood vessels were primary target organs for MNNG following fry exposure, with seminoma, hemangioma, hemangiosarcoma, and various other epithelial and mesenchymal neoplasms occurring. The zebrafish is a responsive, cost-effective lower vertebrate model system in which to study mechanisms of carcinogenesis.
Case Report: Carcinoma of the Extraorbital Lacrimal Gland in a Female Fischer 344 Rat
Authors: Heath James E. , Rahemtullah F. , Fine W. David
Published: February 2008

A large subcutaneous mass was observed at necropsy in the right neck area of a 95-week-old female Fischer 344 rat that served as an untreated control animal in a 2-year carcinogenicity study. Formalin-fixed, paraffin-embedded sections of the mass were stained with hematoxylin and eosin along with the immunohistochemical biomarkers lactoperoxidase, catalase, and amylase. Based on its histomorphological and immunohistochemical features, the lesion was diagnosed as a carcinoma of the extraorbital lacrimal gland.
Malignant Theca Cell Tumor of Rat
Authors: Ozaki Kiyokazu , Narama Isao
Published: February 2008

A large-sized ovarian tumor of theca cell origin was found in a female rat. The mass was located in the right ovary position. Histologically, the tumor was covered by thin fibrous capsule and consisted of a solid area and an abundant necrotic area. Tumor cells were arranged in a storiform or whorled pattern. Connective tissue elements occasionally presented as bundles of dense collagen fibers. Fusiform to elongated cells had oval- to spindle-shaped nuclei with indistinct nucleoli. Large round nuclei and mitotic figures were scattered throughout the tumor cells. These cells were stained positively with S-100 but negatively with vimentin and α—smooth muscle actin. Tumor cells with abundant cytoplasm sometimes contained multiple small-sized lipid vacuoles.
Pituicytoma: Primary Astrocytic Tumor of the Pars Nervosa in Aging Fischer 344 Rats
Authors: Satoh Hiroshi , Iata Hijiri , Furuhama Kazuhisa , Enomoto Makoto
Published: February 2008

We describe 2 cases of a relatively rare tumor diagnosed as pituicytoma in the pars nervosa of rat pituitary. This tumor was spontaneously noted in one 110-week-old female and one 109-week-old male Fischer 344 (F344)/DuCrj rats during 2-year carcinogenicity studies. Although no gross abnormality of the pituitary was detected in the female rat, whitish discoloration and enlargement of the pituitary were observed in the male. Histopathologically, neoplastic cells in both animals possessed pale eosinophilic, often abundant irregular cytoplasm with nuclei of variable size. The tumor cells were arranged in the spindle or sheet cell pattern with indistinct cell boundaries and showed compression or invading proliferation of surrounding tissues. Prominent pleomorphism of the cells was noted in the tumor in the female rat, and mitotic figures were detected in several portions of the tumor in the male rat. Small-sized cells having scanty cytoplasm with deeply staining nuclei seen in the mass were suspected to be microglia. Moreover, isolated single native pars distalis cells were distributed throughout the tumor masses. Immunohistochemically, cytoplasmic foot process of the tumor cells showed a positive immunoreactivity for glial fibrillary acidic protein. On the basis of morphologic characteristics and glial fibrillary acidic protein staining, this tumor is consistent with astrocytoma.
Efficacy and Concentration-Response of Murine Anti-VEGF Monoclonal Antibody in Tumor-Bearing Mice and Extrapolation to Humans
Authors: Mordenti Joyce , Thomsen Karen , Licko Vojtech , Chen Helen , Gloria Meng Y. , Ferrara Napoleone
Published: February 2008

The development of a neovascular supply (angiogenesis) is a major aspect of tumorigenesis. Recent work has indicated that vascular endothelial growth factor (VEGF) is a major regulator of angiogenesis. In vitro and in vivo studies have demonstrated that an anti-VEGF antibody is capable of suppressing the growth of human tumor cell lines. The following study was conducted in tumor-bearing nude mice to evaluate the concentration-response relationship of murine anti-VEGF monoclonal antibody (muMAb VEGF) so that an efficacious plasma concentration of the recombinant humanized form (rhuMAb VEGF) in cancer patients could be estimated. (This study was included in our Investigational New Drug application to support the clinical dosing regimen and projected human safety factors for the toxicology program.) Additionally, the growth dynamics of the tumors were evaluated as a function of dose to explore whether a mechanismic interpretation of tumor growth inhibition by muMAb VEGF is possible. On day 1, A673 human rhabdomyosarcoma cells (2 X 106 cells/mouse) were injected subcutaneously in 188 beige nude mice (16-24 g). Treatment with muMAb VEGF (0.05-5.0 mg/kg; n = 24/group), phosphate-buffered saline (n = 10), or anti-gp120 isotype-matched control antibody (5.0 mg/kg; n =10) began 24 hr later. Each animal received intraperitoneal injections of test material twice weekly for 4 wk. Immediately prior to each dose, 2 mice from each muMAb VEGF group were selected randomly, and plasma was collected for pharmacokinetic evaluation; at the end of the study, samples were collected from all animals for pharmacokinetic evaluation. Tumor dimensions were recorded weekly, and at the end of the study, tumor weight and dimensions were recorded. Satisfactory tumor suppression in nude mice was achieved at muMAb VEGF doses of ≥2.5 mg/kg, where the average trough muMAb VEGF plasma concentration was 30 μg/ml (concentrations in individual animals >10 μg/ml). Assuming the pharmacokinetics of rhuMAb VEGF in patients will resemble the pharmacokinetics of a similar humanized anticancer monoclonal antibodies, a clinical dosing regimen was designed to maintain the rhuMAb VEGF plasma concentration in this efficacious range. This study shows an approach that can be used to estimate a human dosing regimen from preclinical pharmacokinetic/pharmacodynamic data. Because we have just initiated clinical trials with rhuMAb VEGF, we cannot judge clinical outcome in relation to these preclinical predictions; nonetheless, it is hoped that by sharing our approach and thought processes with other investigators we can assist the discovery and development of anticancer therapeutics.
Preclinical Safety Evaluation of rhuMAbVEGF, an Antiangiogenic Humanized Monoclonal Antibody
Authors: Ryan Anne M. , Eppler Dorothy Bates , Hagler Kelly E. , Bruner Richard H. , Thomford Peter J. , Hall Robert L. , Shopp George M. , O'Neill Charles A.
Published: February 2008

Recombinant humanized antivascular endothelial growth factor (rhuMAbVEGF) is a monoclonal IgG, antibody that is being developed as an antiangiogenic agent for use in treating a variety of solid tumors. Preclinical safety studies included an immunohistochemical tissue cross-reactivity study, in vitro hemolytic potential and blood compatibility studies, and multiple dose toxicity studies. Toxicity studies were conducted in cynomolgus monkey because rhuMAbVEGF is pharmacologically active in this species and does not bind rat or mouse vascular endothelial growth factor (VEGF). Following twice weekly administration of rhuMAbVEGF for 4 or 13 wk, young adult cynomolgus monkeys exhibited physeal dysplasia characterized by a dose-related increase in hypertrophied chondrocytes, subchondral bony plate formation, and inhibition of vascular invasion of the growth plate. In addition, decreased ovarian and uterine weights and an absence of corpora lutea were observed in females receiving 10 and 50 mg/kg/dose in the 13-wk study. Both the physeal and ovarian changes were reversible with cessation of treatment. No other treatment-related effects were observed following rhuMAbVEGF administration at doses up to 50 mg/kg. These findings indicate that VEGF is required for longitudinal bone growth and corpora lutea formation and that rhuMAbVEGF can reversibly inhibit physiologic neovascularization at these sites.
Correlation of Toxicity and Pharmacokinetic Properties of a Phosphorothioate Oligonucleotide Designed to Inhibit ICAM-1
Authors: Henry Scott P. , Templin Michael V. , Gillett Nancy , Rojko Jennifer , Levin Arthur A.
Published: February 2008

ISIS 2302 is a phosphorothioate oligodeoxynucleotide with a sequence complementary to the mRNA of human intercellular adhesion molecule 1 (ICAM-1). Hybridization of ISIS 2302 to the mRNA inhibits expression of the ICAM-1 protein in response to inflammatory stimuli. A murine active antisense oligonucleotide, ISIS 3082, has been used for in vivo pharmacology studies and has anti-inflammatory activity in models of organ transplant rejection, ulcerative colitis, and collagen-induced arthritis at doses ranging from 0.03 to 5 mg/kg. The safety assessment for ISIS 2302 includes general toxicity studies up to 6 mo in duration in mice and monkeys, genetic toxicity studies, and reproductive/fertility studies. ISIS 3082 was examined in parallel with ISIS 2302 in mouse toxicity and reproductive studies. The toxicities observed following systemic administration of ISIS 2302 and ISIS 3082 were similar and consistent with those observed for other compounds in this chemical class and, therefore, are independent of the suppression of ICAM-1 expression. Toxicokinetic evaluation demonstrated that toxicities occurred in organs containing the highest concentrations of ISIS 2302. Evidence of immune stimulation, including dose-dependent splenomegaly, lymphoid hyperplasia, and multiorgan mixed mononuclear cell infiltrates, was the most common finding in rodent studies. Monkeys were much less sensitive than mice to immune stimulation. Kidney contained the highest concentrations of ISIS 2302. Morphologic changes observed in kidney included atrophic and regenerative changes in proximal tubular epithelium; however, there was no evidence of functional abnormalities. Additional histologic changes noted in proximal tubular epithelium included basophilic granules, which were reflective of oligonucleotide distribution and uptake in these cells. Liver also contained high concentrations of oligonucleotide, which were associated with Kupffer cell hypertrophy in mice. Changes in serum transaminases, cholesterol, and triglycerides were reflective of hepatic alterations. In monkeys, high concentrations of oligonucleotide caused a transient increase in clotting times and activation of the alternative complement pathway. All toxicities associated with ISIS 2302 were reversible and occurred at doses well above those required for pharmacologic activity or currently used in clinical trials. In addition, there has been no evidence of genetic toxicity associated with ISIS 2302, and no changes in reproductive performance, fertility, or fetal development have been noted in animals treated with ISIS 2302 or ISIS 3082.
Revolution through Genomics in Investigative and Discovery Toxicology
Authors: Rodi Charles P. , Bunch Roderick T. , Curtiss Sandra W. , Kier Larry D. , Cabonce Marc A. , Davila Julio C. , Mitchell Michael D. , Alden Carl L. , Morris Dale L.
Published: February 2008

The remarkable technologic and methodologic advances spurred on by the Human Genome Project are being applied throughout the life sciences. In the field of toxicology, high-resolution assays now make it possible to discover virtually all the differences in gene expression brought on by exposure to a particular xenobiotic. There are 2 principal approaches used to build a catalog of changes in gene expression: hybridization microarrays and gel-based methods, such as differential display and AFLP™-based mRNA fingerprinting. The power of such approaches is exemplified by the identification of more than 300 genes that differ in expression level by at least 2-fold in response to the nongenotoxic rodent liver carcinogen phenobarbital.
Utilization of Genetically Altered Animals in the Pharmaceutical Industry
Authors: Rudmann Daniel G. , Durham Stephen K.
Published: February 2008

The study of transgenic and gene-deleted (knockout) mice provides important insights into the in vivo function and interaction of specific gene products. Within the pharmaceutical industry, genetically altered mice are used predominantly in discovery research to characterize the diverse functions of one or multiple gene products or to establish animal models of human disease for proof-of-concept studies. We recently used genetically altered animals in drug discovery to examine the NF-KB family of transcriptional regulatory genes and to elucidate their essential role in the early onset of immune and inflammatory responses. Transgenic and knockout mice are also useful in drug development, because questions regarding risk assessment and carcinogenesis, xenobiotic metabolism, receptor- and ligand-mediated toxicity, and immunotoxicity can be evaluated using these genetically altered mice. For example, the p53 knockout mouse is one of several genetically altered mice whose use may increase the sensitivity and decrease the time and cost of rodent carcinogenicity bioassays. As with any experimental model system, data obtained from genetically altered mice must be interpreted carefully. The complete inactivation of a gene may result in altered expression of related genes or physiologic compensation for the loss of the gene product. Consideration must also be given to the genetic background of the mouse strain and the impact of strain variability on disease or toxicity models. Despite these potential limitations, knockout mice provide a powerful tool for the advancement of drugs in the pharmaceutical industry.
Preclinical Development of Agents for the Treatment of Osteoporosis
Authors: Hartke James R.
Published: February 2008

Because of the high cost and long time frame of clinical testing, animal models play a crucial role in the identification and selection of agents for the treatment of osteoporosis. The use of animal models early in a program focuses on the establishment of efficacy, while animal models used later in a program to examine bone safety. More specifically, animal models are used to gain information on the skeletal mechanism of action, to examine multiple skeletal sites (axial and appendicular), and to examine the effects of higher doses than will be used in humans. Animal models also predict the usefulness of surrogate markers in clinical trials, such as formation and resorption markers, as well as bone density. The hazard of using surrogate markers for fracture prevention is highlighted by high dose fluoride administration, which can increase bone density (considered a strong predictor of fracture protection) while not protecting against fractures. Estrogen-deficient models are most commonly used to mimic the postmenopausal bone loss in women; these models are characterized by increased bone turnover and a negative bone balance. The timing of the administration of the new therapy in animal models can help determine whether the agent will be more effective in the prevention of osteoporosis or in the treatment of established osteoporosis. New methods for the measurement of bone mass or volume are less invasive, require shorter acquisition time, and have enhanced resolution, resulting in increased knowledge concerning architectural changes and specific sites of bone deposition. Finally, the measurement of biomechanical strength of bones from animal models can be used to predict protective effects on fracture rates in clinical trials. When used in combination with other methods, animal models can greatly increase our understanding of the pathophysiology of osteoporosis and can expedite the development of new therapies.
Urinary Tract Toxicity in Rats Following Administration of β3-Adrenoceptor Agonists
Authors: Waghe Madhav , Westwood Russell , Nunn Gary , Kalinowski Adam , Aldridge Andrew
Published: February 2008

ZD7114, [( S)-4-[2-(2-hydroxy-3 phenoxypropylamine)ethoxy]-N-(2-methoxyethyl) phenoxyacetamide], and ZD2079, [(R)-N-(2-[4-(carboxymethyl)phenoxy]ethyl)- N-(β-hydroxyphenethyl)ammonium chloride], are β3-adrenoceptor stimulants with selectivity for brown adipose tissue. ZD7144 is the hydrochloride salt of the S-enantiomer of the racemic amide ZD2079. They were developed as potential novel treatments for obesity and non-insulin-dependent diabetes mellitus. Male and female rats were dosed separately by gavage for a minimum of 28 days with 0, 10, 50, and 500 mg/kg/day of ZD7114 or with 0, 10, 30, and 150 mg/kg/day of ZD2079. Two further groups of male and female rats were dosed with 0 and 500 mg/kg/day of ZD7114 for 28 days and were then allowed a 6-wk, undosed withdrawal period. At high doses, both compounds caused urinary tract toxicity, which primarily affected the distal tubules and collecting ducts of the kidney via tubular necrosis. They also caused ureteric inflammation, cystitis, and accumulation of crystalline inclusions throughout the urinary tract. As a result of urinary tract toxicity, affected animals from one or both studies showed reduced red blood cell indices, lower platelet counts, and higher white cell counts. Blood chemistry revealed lower plasma concentrations of glucose (7.28 ± 1.37 compared to 8.11 ± 0.65 for the control) and total protein (63.42 ± 3.65 compared to 69.17 ± 3.24 for the control) and increased plasma urea (37.15 ± 19.96 compared to 8.09 ± 0.87 for the control). Urinalysis showed an increase in the number of crystals, blood, and protein. In the urinary tract, the severe crystalluria with accumulation of crystalline material indicated that this may have a role in the etiology of the target organ toxicity. Poor solubility of the compounds at normal urinary pH was considered a possible mechanism for the crystalluria.
Intestinal T Lymphocytes of Different Rat Strains in Immunotoxicity
Authors: Bruder Marc C. , Spanhaak Steven , Bruijntjes Joost P. , Michielsen Carola P.P.C. , Vos Joseph G. , Kuper C. Frieke
Published: February 2008

In order to study the intestinal mucosal immune cells, with emphasis on single T lymphocytes, an inventory was made of single and organized lymphocytes in the epithelium and lamina propria of the small intestines of untreated Wistar, Fischer 344, and Lewis rats. The single and organized lymphocytes were examined microscopically. In addition, the single lymphocytes in the epithelium (IEL) and lamina propria (LPL) were analyzed by flow cytometry. Next, the use of flow cytometry analysis was explored to detect changes in the IEL T-lymphocyte population in subacute oral studies with the immunomodulating agents azathioprine and hexachlorobenzene. Untreated random-bred Wistar rats exhibited a large interindividual variability in IEL composition, while the variability was small in inbred Fischer 344 and Lewis rats. The explorative study with the 2 model immunomodulating compounds demonstrated that hexachlorobenzene increased the number of intraepithelial T lymphocytes with CD8+ phenotype at the cost of T cells with CD4+ phenotype in Lewis rats. Azathioprine did not induce distinct effects on the percentages of IEL. The data indicate that the intraepithelial lymphocytes in the intestines are a potential target for orally administered immunomodulating compounds and should therefore receive more attention in toxicologic pathology studies.
Review Article
Authors: Mossman Brooke T.
Published: February 2008

The National Institute of Environmental Health Sciences (NIEHS) supports a number of training programs for predoctoral and postdoctoral (D.V.M., M.D., Ph.D.) fellows in toxicology, epidemiology and biostatistics, and environmental pathology. At the Experimental Biology meeting in April 1997, the American Society of Investigative Pathology (ASIP) sponsored a workshop including directors, trainees, and other interested scientists from several environmental pathology programs in medical and veterinary colleges. This workshop and a related session on "Novel Cell Imaging Techniques for Detection of Cell Injury" revealed advances in molecular and cell imaging approaches as reviewed below that have a wide applicability to toxicologic pathology.
The Marginalization of Hormesis
Authors: Calabrese Edward J. , Baldwin Linda A.
Published: February 2008

Despite the substantial development and publication of highly reproducible toxicological data, the concept of hormetic dose-response relationships was never integrated into the mainstream of toxicological thought. Review of the historical foundations of the interpretation of the bioassay and assessment of competitive theories of dose-response relationships lead to the conclusion that multiple factors contributed to the marginalization of hormesis during the middle and subsequent decades of the 20th Century. These factors include the following: (a) the close association of hormesis with homeopathy, which led to the hostility of modern medicine toward homeopathy, thereby creating a guilt-by-association framework, and the carryover influence of that hostility toward hormesis in the judgements of medically based pharmacologists/toxicologists; (b) the emphasis of high-dose effects linked with a lack of appreciation of the significance of the implications of low-dose stimulatory effects; (c) the lack of an evolution-based mechanism(s) to account for hormetic effects; and (d) lack of appropriate scientific advocates to counter aggressive and intellectually powerful critics of the hormetic perspective.
Chemical Hormesis: Its Historical Foundations as a Biological Hypothesis
Authors: Calabrese Edward J. , Baldwin Linda A.
Published: February 2008

Despite the long history of hormesis-related experimental research, no systematic effort to describe its early history has been undertaken. The present paper attempts to reconstruct and assess the early history of such research and to evaluate how advances in related scientific fields affected the course of hormesis-related research. The purpose of this paper is not only to satisfy this gap in current knowledge but also to provide a foundation for the assessment of how the concept of hormetic dose-response relationships may have affected the nature of the bioassay, especially with respect to hazard assessment practices within a modem risk assessment framework.
Eosinophilic Granulated Cells Comprising a Tumor in a Fischer Rat
Authors: Miyajima Rumiko , Hosoi Masayo , Yamamoto Shinji , Mikami Shin-Ichi , Yamakawa Seiki , Iwata Hijiri , Enomoto Makoto
Published: February 2008

A systemic tumor developed in multiple organs, including spleen, bone marrow, lymph nodes, liver, ovaries, and thoracic and lumbar vertebrae, of a female F344Du/Crj rat. The tumor was composed of round to indented mononuclear cells containing abundant large eosinophilic granules in the cytoplasm. The peripheral blood smear revealed that the large granules in the cytoplasm of the tumor cells were stained basophilic with Giemsa, suggesting a basophil or mast cell origin. However, these granules did not show metachromasia with toluidine blue and were stained blue to dark blue with phosphotungstic acid hematoxylin. Cellular morphology and characteristics in the specific stains of tumor cells suggested the development of a tumor of globule leukocytes in a F344Du/Crj rat.
Disseminated Thrombosis and Bone Infarction in Female Rats Following Inhalation Exposure to 2-Butoxyethanol
Authors: Nyska Abraham , Maronpot Robert R. , Long Philip H. , Roycroft Joseph H. , Hailey James R. , Travlos Gregory S. , Ghanayem Burhan I.
Published: February 2008

Groups of 10 male and 10 female F344/N rats were exposed to 0, 31, 62.5, 125, 250, and 500 ppm of 2-butoxyethanol (BE) by inhalation, 6 hr/day, 5 days/wk, for 13 wk. Four moribund female rats from the 500 ppm group were sacrificed during the first 4 days of exposure, and 1 moribund female from the same group was sacrificed during week 5. Dark irregular mottling and/or loss of the distal tail were noted in sacrificed moribund rats. Similar gross lesions were noted in the terminally sacrificed females exposed to 500 ppm BE. Histologic changes noted in the day 4 sacrificed moribund rats included disseminated thrombosis involving the coccygeal vertebrae, cardiac atrium, lungs, liver, pulp of the incisor teeth, and the submucosa of the anterior section of the nasal cavity. Alterations noted in coccygeal vertebrae from the 500 ppm sacrificed moribund rats included ischemic necrosis and/or degeneration of bone marrow cells, bone-lining cells, osteocytes (within cortical and trabecular bone), and chondrocytes (both articular and growth plate), changes that are consistent with an infarction process. The moribund female rat that was sacrificed during week 5 and those female rats treated with 500 ppm and sacrificed following 13 wk of treatment lacked thrombi, but they had coccygeal vertebral changes consistent with prior infarction and transient or complete bone growth arrest. No bone lesions or thrombi were noted in the male rats treated with the same doses of BE. In conclusion, exposure to 500 ppm BE vapors caused acute disseminated thrombosis and bone infarction in female rats. Possible pathogenic mechanisms are discussed.
Renal Changes Associated with Naproxen Sodium Administration in Cynomolgus Monkeys
Authors: Leach Michael W. , Frank Doyle W. , Berardi Mark R. , Evans Ellen W. , Johnson Robert C. , Schuessler David G. , Radwanski Elaine , Cartwright Mark E.
Published: February 2008

Naproxen sodium was administered to cynomolgus monkeys (Macaca fascicularis) by oral gavage at daily doses of 44, 88, or 176 mg/kg for 2 wk (2 monkeys/gender) or of 44 mg/kg for 13 wk (4 monkeys/gender). Body weight loss occurred in at least one monkey in all naproxen sodium-dosed groups in the 2-wk (up to 16% loss) and 13-wk (up to 22% loss) studies. Increases in plasma naproxen concentrations were dose proportional between 44 and 88 mg/kg but were less than dose proportional between 88 and 176 mg/kg. Up to 2-fold increases in creatinine and/or serum urea nitrogen values as well as higher renal weights occurred in monkeys receiving 176 mg/kg for 2 wk or 44 mg/kg for 13 wk. Microscopically, renal changes were observed in all naproxen sodium-dosed groups. Renal findings after 2 wk of exposure included increased interstitial ground substance, tubular dilatation, and tubulointerstitial nephritis; in the 13-wk study, cortical tubular atrophy and interstitial fibrosis were also observed. These studies identify the kidney as the target organ of naproxen sodium in cynomolgus monkeys.
Evaluation of the Renal Effects of an Antisense Phosphorothioate Oligodeoxynucleotide in Monkeys
Authors: Monteith David K. , Horner Michelle J. , Gillett Nancy A. , Butler Madeline , Geary Richard , Burckin Todd , Ushiro-Watanabe Tanya , Levin Arthur A.
Published: February 2008

Antisense phosphorothioate oligodeoxynucleotides are therapeutic agents that provide target specificity resulting from Watson-Crick base pairing. However, there are nonspecific effects that in some instances result in toxicity. These compounds accumulate in the kidney and induce renal proximal tubular degeneration at high doses. The relationship between accumulation of phosphorothioate oligodeoxynucleotides in the kidney, indicators of renal toxicity, and histomorphology were investigated in rhesus monkeys. Monkeys received vehicle or an escalating dose regimen of 3, 10, 40, and 80 mg/kg of ISIS 2105 and were then evaluated for changes in clinical pathology indices, urinalysis parameters, and renal histopathology. Urinalysis revealed an increase in protein levels and a slight increase in blood content following the third 40 mg/kg dose and continuing through the 80 mg/kg doses, whereas other urinary markers of renal toxicity were unchanged. Creatinine clearance was slightly decreased in monkeys during the 80 mg/kg dose cycle. Granulation in the cytoplasm of proximal tubular epithelial cells was evident by microscopic examination of kidney and was present at all doses examined and increased with dose. Immunohistochemical staining localized the oligodeoxynucleotide within these granules. Histopathologic changes consisting of minimal to moderate tubular degeneration were present only at the higher doses of 40 and 80 mg/kg and at high tissue concentrations, and these changes occurred concurrent with functional alterations, whereas lower doses (≤10 mg/kg) did not affect a pathologic or functional change.
Eosinophilic Gastroenterocolitis in Iron Lactate-Overloaded Rats
Authors: Narama Isao , Ozaki Kiyokazu , Matsushima Syuuichi , Matsuura Tetsuro
Published: February 2008

Eosinophilic gastroenterocolitis with peripheral eosinophilia was induced in rats fed a diet containing 2.5% or 5.0% iron lactate for 3 mo. Additional findings consistent with iron overload were also observed. Microscopically, the lesions consisted of eosinophilic infiltrations in the mucosa and submucosa along the whole length of the gastrointestinal tracts, increased surface area of the gastric mucosal propria covered with mucous cells, and increased apoptotic bodies in the gastric glandular neck of rats in the 2.5% and 5.0% groups. An increased number of intraepithelial globule leukocytes in the gastric and intestinal lamina propria was also observed in the 5.0% group. Globule leukocytes in the gastric mucosa contained obviously enlarged granules in their cytoplasm in these rats. The granules of the globule leukocytes were positive for rat mast cell protease II, suggesting the mastocyte origin of these cells. Although severe infiltration of eosinophils and globule leukocytes suggested a type-1 hypersensitivity reaction, other features such as an increasing vascular permeability were not detected. Serum IgE levels in the 5.0% and control groups were <3 ng/ml. Final body weights of male and female rats of the 5.0% group were suppressed to 70% and 90%, respectively, of those of the control rats, whereas food consumption was comparable to that of the control group. The morphologic characteristics of the gastrointestinal lesions and peripheral eosinophilia induced in rats fed iron lactate were very similar to those in some cases of eosinophilic gastroenterocolitis in humans and other animals.
Effects of Neonatal Diethylstilbestrol (DES) Exposure on Morphology and Growth Patterns of Endometrial Epithelial Cells in CD-1 Mice
Authors: Yoshida Akiyoshi , Newbold Retha R. , Dixon Darlene
Published: February 2008

The effects of neonatal diethylstilbestrol (DES) exposure on the morphology and proliferating patterns of endometrial epithelial cells were investigated at various stages of development in mice. Female CD-1 mice were given daily subcutaneous injections of 2 μg of DES in corn oil or corn oil alone (control) at 1-5 days of age and were killed at 5, 6, 7, 8, 15, and 22 days of age. At 5 days of age, the uteri of DES-treated mice had expanded lumina and undulated luminal surfaces lined by slightly elongated epithelial cells. At 6-8 days of age, marked infolding of clusters of hypertrophic elongated luminal epithelial cells was present; uteri had disorganized endometrial stromal and myometrial layers. At 15 and 22 days of age, the tissues from DES-treated mice had decreased numbers of endometrial glands, minimal stromal fibrosis, and smaller uterine horns than did the controls. Ultrastructurally, the endometrial epithelial cells of DES-treated mice at 5 and 8 days of age had distorted nuclei with condensed matrix and abundant secretory granules associated with rough endoplasmic reticulum and Golgi apparatus. At 8 days of age, an accumulation of fingerlike cytoplasmic processes that extended into the separated intercellular spaces and along the basal aspects of the endometrial epithelial cells were also observed. At 5-8 days of age, the proliferative activity of endometrial epithelial cells in DES-treated mice, identified by bromodeoxyuridine labeling, was significantly lower (10.5-1.7%) than that of the controls (25.5-19.8%). In situ analysis of endometrial luminal epithelial cells for DNA fragmentation representing apoptosis revealed ≤0.1% and > 10% in the DES-treated and control mice at 5-8 days of age, respectively. The data show that cell cycle kinetics, in addition to changes in morphology, are altered in the developing mouse uterus following neonatal exposure to DES.
Hepatoprotection by Dimethyl Sulfoxide. I. Protection When Given Twenty-Four Hours After Chloroform or Bromobenzene
Authors: Lind Richard C. , Gandolfi A. Jay
Published: February 2008

Dimethyl sulfoxide (DMSO) has previously been reported to protect against hepatotoxicity resulting from chloroform (CHCl3) or bromobenzene (BB) when given 10 hr after the toxicant. The object of these studies was to further demonstrate the latent protective ability of DMSO by administering it at a much later time (24 hr) following toxicant exposure. In addition, a more detailed evaluation of the lesions was performed to better characterize the lesion progression and resolution. Male Sprague-Dawley rats received a hepatotoxic oral dose of either CHCl3 (1.0 ml/kg) or BB (0.5 ml/kg) and then received 2 ml/kg DMSO intraperitoneally 24 hr later. With both toxicants, limited centrilobular lesions were already present by the time DMSO was administered. Without treatment, liver injury rapidly progressed so that by 48 hr it occupied 40-50% of the liver, with accompanying large increases in plasma alanine aminotransferase (ALT) activity. Administration of DMSO greatly attenuated lesion development for both toxicants; the area injured was reduced by more than 4-fold, accompanied by a decrease in 48 hr ALT activity of 8-16-fold. The ability of DMSO to intervene in the development of liver injury at such a late time appears to be unique and may provide insight into therapies for acute xenobioticinduced hepatitis.
Neurotoxic Effects of 2,5-Hexanedione on Normal and Neurofilament-Deficient Quail
Authors: Hirai Takuya , Mizutani Makoto , Kimura Takashi , Ochiai Kenji , Umemura Takashi , Itakura Chitoshi
Published: February 2008

The neurotoxic effects of 2,5-hexanedione (2,5-HD) were investigated using neurofilament (NF)-deficient (Quv) Japanese quail in comparison with normal Japanese quail. Both Quv and normal Japanese quail were inoculated intraperitoneally with 350 mg/kg/day 2,5-HD for 6 consecutive wk. The results of 2,5-HD exposure differed substantially between the 2 strains of Japanese quail. The 2,5-HD-exposed normal quail showed leg paralysis about 4 wk after initiation of dosing. Some treated normal quail fell into dysstasia and died of nutritional disturbances. Histologically, 2,5-HD-treated normal quail had NF-rich axonal swellings and degeneration in the distal parts of the peripheral nerves, spinal cord, and cerebellar peduncles. In contrast, 2,5-HD-injected Quv quail showed tonic convulsion, ataxia gait, severe quivering, and excitation about 2-3 days after administration. Some treated Quv birds died immediately after systemic tonic convulsion, probably because of asphyxia. Although all treated Quv quail showed neurologic signs, there were no recognizable 2,5-HD-induced lesions in the nervous system. After about 4-6 wk of dosing, 2,5-HD induced distal axonopathy in normal quail and acute neurotoxicity in Quv quail.
Toxicologic and Carcinogenic Effects of the Type IV Phosphodiesterase Inhibitor RP 73401 on the Nasal Olfactory Tissue in Rats
Authors: Pino Michael V. , Valerio Marion G. , Miller Glen K. , Larson Jeffrey L. , Rosolia David L. , Jayyosi Zaid , Crouch Christopher N. , Trojanowski John Q. , Geiger Lee E.
Published: February 2008

RP 73401, a type IV phosphodiesterase inhibitor, caused toxic effects in the nasal olfactory region of Sprague-Dawley rats when administered by either oral or inhalation exposure. A single oral administration of RP 73401 (at a dose of ≥50 mg/kg) or 5-day inhalation exposure (1 hr/day) at a dose of approximately 1.0 mg/kg per day caused degeneration and sloughing of the olfactory surface epithelium. Degeneration and loss of Bowman's glands were noted in the underlying lamina propria and submucosa. Electron microscopy of these lesions demonstrated that sustentacular cells and the epithelial cells lining Bowman's glands were the primary target cells in the olfactory mucosa. The earliest ultrastructural changes detected in these cells were dilatation and vesiculation of the endoplasmic reticulum, suggesting that metabolic activation is important for the toxic effects. In repeated-dose studies, 13 wk of oral dosing at 2.0 or 6.0 mg/kg per day resulted in subtle disorganization of the olfactory epithelium, whereas basal cell hyperplasia in the olfactory epithelium was identified in a 6-month inhalation study at a dose of 1.0 mg/kg per day. A 2-yr inhalation carcinogenicity study resulted in tumors of the nasal olfactory region in rats treated at 0.5 and 1.0 mg/kg per day. Most tumors were classified as olfactory neuroblastomas, and immunohistochemistry on selected tumors was consistent with their being of neuroectodermal origin. Of the species studied (rat, mouse, and dog), the olfactory toxicity of RP 73401 was confined to the rat, and the toxicity was likely related to metabolic activation by olfactory epithelial cells rather than the phosphodiesterase activity of the compound.
Hepatic Effects in Beagle Dogs Administered Atorvastatin, a 3-Hydroxy-3-Methylglutaryl Coenzyme A Reductase Inhibitor, for 2 Years
Authors: Walsh Kathleen M. , Rothwell Charles E.
Published: February 2008

The chronic toxicity of atorvastatin (AT), an inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase, was evaluated in beagle dogs. Dogs were treated with 0, 10, 40, or 120 mg/kg of AT daily. Treatment lengths were 52 wk, 52 wk followed by 12 wk without drug, or 104 wk. Decreases in cholesterol levels were dose related and stable throughout the treatment period. Increases in alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase were transient and dose related in severity at ≥40 mg/kg. Two dogs administered 120 mg/kg of AT daily were sacrificed moribund during the first 9 wk of treatment. Hepatic lesions were reversible with or without continued treatment and dose related in severity and distribution. Hepatic microgranulomas and hepatocellular degeneration were seen at the 120-mg/kg dose in dogs sacrificed before 53 wk. Before 53 wk, hepatocellular lipofuscin deposits were increased in dogs given ≥40 mg/kg of AT daily but were similar to controls after 12 wk without drug and after 104 wk of continuous treatment. Bile stasis occurred in dogs given ≥40 mg/kg of AT daily at all time points but was less severe after reversal and at week 104 compared with week 52.
Human Natural Tumor Necrosis Factor α Induces Multiple Endocrine and Hematologic Disorders in Rats
Authors: Kakinuma Chihaya , Hamada Yoshimasa , Futamura Yoshihiro , Kuwayama Chitose , Shimoi Akihito , Shibutani Yasunori
Published: February 2008

Slc:Wistar male rats treated with human natural tumor necrosis factor α (hn TNF-α, 3 X 105 Japan reference units/kg intravenously) for 3 months showed histologic vacuolation of basophils in the anterior pituitary, hyperplasia of the thyroidal follicular epithelium, and hyperplasia of the testicular interstitial cells. The vacuolated basophils were immunohistochemically shown to be thyrotrophs. In addition, there were decreases in plasma levels of triiodothyronine (T3), thyroxin (T4), and testosterone, and an increase in thyroid-stimulating hormone (TSH). The number of lymphocytes in the marginal zones of lymphoid follicles in spleen and lymph nodes and B-lymphocytes in the peripheral blood decreased. Hyperplasia of hematopoietic cells in the bone marrow and decreases in both leukocytes and erythrocytes in the peripheral blood were prominent. Hyperplasia of bile ductular epithelial cells with periportal mononuclear cell infiltration in the liver and increased cellularity in alveolar walls in the lung were also characteristic. In in vitro studies, hn TNF-α inhibited both proliferation and peroxidase activity of thyroid follicular epithelial cells. These findings demonstrate that hn TNF-α may induce histologic vacuolation of thyrotrophs by causing a decrease in plasma levels of T 3 and T 4; hyperplasia of the thyroid follicular epithelium, which may be attributed to the increased plasma level of TSH; hyperplasia of testicular interstitial cells, by lowering the plasma level of testosterone; hyperplasia of bile ductular epithelial cells; hyperplasia of hematopoietic cells in bone marrow; and the increase in cellularity in pulmonary alveolar walls. In addition, hn TNF-α may suppress the differentiation of B-lymphocytes.
Contrast Medium- and Mannitol-Induced Apoptosis in Heart and Kidney of SHR Rats
Authors: Jun Zhang  , Duarte Cristobal G. , Ellis Sydney
Published: February 2008

The induction of apoptosis by contrast media (CM) and mannitol (M) was investigated in the hearts and kidneys of 12-mo-old male SHR rats. Ten groups of 3 SHR rats received a dose of 5 ml/kg of one of the following: Hypaque (H)-30. H-60, H-76, Omnipaque (O)-140, O-350, mannitol (M)-4%, M-9%, M-19%, M-27%, or saline (S). DNA fragmentation was detected using the terminal deoxynucleotidyl transferase-mediated [TdT] dUTP nick-end labeling (TUNEL) method, and the morphology characteristics of apoptosis were confirmed in cardiac and renal cells. The immunoreactivities of Bcl-2, Bax, and p53 were assessed immunohistochemically in the kidneys. Apoptosis occurred in cardiac myocytes and renal tubular and glomerular cells as well as in vascular endothelial and smooth muscle cells of the heart and kidneys. The high frequency of apoptosis correlated significantly with the increase in the osmolality of the H, O, and M. The increased Bax, the increased p53, and the decreased Bcl-2 immunoreactivities were detected in H- or O-treated, but not in M-treated, rats. These findings suggest that CM and M activate cardiac and renal apoptosis by different mechanisms and that the apoptotic process may be implicated in acute heart and renal damage.