[Show abstract][Hide abstract] ABSTRACT: The common marmoset (Callithrix jacchus) is now widely used in various research fields, including toxicology. However, information about the background pathology of this species is scarce. Here, we report a case of rhabdomyosarcoma that spontaneously occurred in a common marmoset. A 44-month-old male common marmoset was euthanized due to bilateral hind limb paralysis. At necropsy, a 2×2×5-cm intramuscular mass was observed in the lower right back. Histologically, the mass was mainly composed of interlacing bundles of spindle-shaped tumor cells. Immunohistochemically, the tumor cells were positive for myogenin, desmin, vimentin and alpha-smooth muscle actin. Ultrastructurally, the tumor cells contained bundles of myofilaments with Z-band-like structures. Thus, the tumor was diagnosed as a rhabdomyosarcoma. To our knowledge, this is the first report of spontaneous rhabdomyosarcoma that was definitely diagnosed in the common marmoset.
Preview · Article · Jun 2013 · Journal of Toxicologic Pathology
[Show abstract][Hide abstract] ABSTRACT: A female congenic rat produced by repeated backcrossing of Nihon rats, a model for hereditary renal cell carcinoma, to Brown Norway rats was necropsied at 24 months of age. At necropsy, a white mass about 1 centimeter in size was observed in the thoracic cavity, and the mass partly adhered to the esophagus and the diaphragm. Histologically, the mass was clearly circumscribed by connective tissue, and consisted of neoplastic cuboidal epithelial cells that showed cystic tubular proliferation. Some islands of well-differentiated hepatocytes and some vessels were observed in the mass. Immunohistochemically, the tumor cells were strongly positive for cytokeratin and partly positive for vimentin but were negative for mesothelin and Von Willebrand Factor. The positive rate for Ki-67 was 2.4%. Based on these histological and immunohistochemical evidences, we diagnosed this tumor as a cystic cholangioma that might have arisen from the ectopic hepatic tissue in the thoracic cavity.
Preview · Article · Mar 2012 · Journal of Toxicologic Pathology
[Show abstract][Hide abstract] ABSTRACT: In the present study, we investigated the histological, immunohistochemical and
ultrastructural characteristics of cytoplasmic blood plasma inclusions that spontaneously
occurred in a rat liver. Histologically, a number of cytoplasmic inclusions were observed
in the liver of an 8-week-old female SD rat. These inclusions were strongly positive for
PAS staining and resistant to diastase digestion. Immunohistochemical analyses revealed
that these inclusions were positive for albumin and IgG; however, most of them were
negative for LAMP-1 and LAMP-2. Ultrastructurally, the inclusions were surrounded by
limiting membranes and composed of moderately electron dense, homogenous materials. These
characteristics described here represent valuable information for pathological examination
in toxicity studies.
Full-text · Article · Dec 2011 · Journal of Toxicologic Pathology
[Show abstract][Hide abstract] ABSTRACT: Hyaline glomerulopathy with tubulo-fibrillary deposits was observed in two young female ddY mice. One of the mice showed gross systemic edema and bilateral enlargement and pale color of the kidneys, whereas no significant gross findings were noted in the other mouse. Microscopically, a large number of the glomeruli in both mice were enlarged because of diffuse and global deposition of amorphous eosinophilic materials. The deposits were negatively stained with Congo red and positively stained with IgG, IgM, IgA, C3, and periodic acid-Schiff. Electron microscopic examination revealed microtubular and fibrillary deposits with diameters of 80-100 and 9-16 nm, respectively, in the subendothelial space of the glomeruli. These features are histopathologically similar to immunotactoid glomerulopathy or fibrillary glomerulonephritis according to the classification of human glomerular lesions. Understanding of these characteristics of hyaline glomerulopathy in ddY mice is essential when evaluating pharmacological, pharmacokinetic, and toxicological studies using this mouse strain.
Full-text · Article · Aug 2011 · Toxicologic Pathology
[Show abstract][Hide abstract] ABSTRACT: An 18-month-old male Brown Norway (BN) rat showed a grayish-white subcutaneous
mass in the right cheek. Histologically, the mass was composed of highly
pleomorphic cells producing collagen. Immunohistochemical analysis showed that
the tumor cells were strongly positive for vimentin and partially positive for
Ki-67; however, they were negative for ED-1, ED-2, S-100, cytokeratin, desmin
and myoglobin. Ultrastructurally, the cytoplasms of the tumor cells contained
well-developed rough endoplasmic reticulum. Thus, the tumor had no
characteristic feature other than collagen production and was diagnosed as a
Preview · Article · Dec 2010 · Journal of Toxicologic Pathology
[Show abstract][Hide abstract] ABSTRACT: A male ferret, which was purchased from abroad at 9 months of age, had shown significant weight loss starting at 13 months of age. The ferret subsequently showed decreasing motor activity and recumbency and was euthanized at 14 months of age. At necropsy, a white, quail egg-sized mass was found in the mesentery. Histopathologically, multifocal granulomas consisting of necrotic foci, macrophages, fibroblasts and plentiful fibrous connective tissues were observed in the mesenteric mass. Surrounding the granulomas, inflammatory cell infiltration consisting of neutrophils, lymphocytes and plasmacytes was observed diffusely and significantly. Immunohistochemistry revealed small numbers of macrophages around necrotic foci that were positively stained for anti-mouse feline coronavirus. Electron microscopically, the cytoplasm of the macrophages contained viral particles, which were identified as coronavirus. The histopathological features in this ferret were similar to those in cats with feline infectious peritonitis (FIP). This was the first case in ferrets in Japan.
Preview · Article · Jun 2010 · Journal of Toxicologic Pathology
[Show abstract][Hide abstract] ABSTRACT: An immunohistochemical staining method for prohibitin, a 30-kDa protein located in the inner membrane of mitochondria, is used for detection of mitochondria on formalin-fixed paraffin-embedded sections. Methapyrilene hydrochloride (MP), which is known to increase mitochondria in periportal hepatocytes, was administered once by oral gavage to male rats at a dose of 100 mg/kg. Hypertrophy with eosinophilic granules was noted in the periportal hepatocytes treated with MP. Immunohistochemical staining with prohibitin antibody demonstrated a positive reaction to eosinophilic granules. Electron microscopy showed an increased number of mitochondria in the periportal hepatocytes treated with MP compared to the control. Although electron microscopy is a useful tool to detect ultrastructural changes, an immunohistochemical examination with anti-prohibitin antibody is a simple and easy method for detecting cytoplasmic mitochondria quantitatively.
No preview · Article · Jan 2008 · Journal of Toxicologic Pathology
[Show abstract][Hide abstract] ABSTRACT: To investigate mechanisms underlying accelerated carcinogenesis in mice carrying a human prototype c-Ha-ras gene (rasH2 mouse), mutations and the expression profile of the transgene were evaluated in 14 tumors induced by a single injection of ethylnitrosourea (ENU), with or without additional beta-estradiol 3-benzoate (EB) treatment. Although no codon 12 mutations were detected, changes in codon 61 were evident in all lung adenocarcinomas, skin squamous cell carcinomas and forestomach squamous cell carcinomas examined. The mRNA levels of the transgene in these lesions were also elevated 1.71- to 4.77-fold, 3.04- to 5.18-fold, and 3.00- to 5.67-fold, respectively, in comparison with those in the normal livers of rasH2 mice. The results obtained in this study suggest that mutations in codon 61 and amplification of the transgene play key roles in the carcinogenesis induced by ENU in rasH2 mice.
[Show abstract][Hide abstract] ABSTRACT: To clarify the threshold dose of thyroid tumor-promoting effects of xylazine hydrochloride (XZ), male F344 rats received pulverized basal diet containing 0, 250, 500, or 1000 ppm XZ for 26 weeks with or without initiation of 2400 mg/kg N-bis(2-hydroxypropyl)nitrosamine (DHPN). Thyroid weights significantly increased in the groups with or without DHPN initiation that were given 500 ppm XZ or more. The serum thyroxine (T4) and triiodothyronine (T3) levels decreased significantly in the XZ 250 and XZ 1000 ppm groups, respectively, although there were no remarkable changes in the serum thyroid-stimulating hormone (TSH) levels. Histopathologically, follicular cell hyperplasias and adenomas were induced in the DHPN-alone and DHPN+XZ groups, and the incidences and multiplicities of these lesions in the DHPN groups treated with 500 ppm XZ or more were significantly higher than those in the DHPN alone group. These results suggest that the threshold dose of rat thyroid tumor-promoting effects of XZ is between 250 and 500 ppm under the present experimental condition.
[Show abstract][Hide abstract] ABSTRACT: In our previous study, uterine endometrial stromal sarcomas and atypical hyperplasias of the endometrial glands were induced in heterozygous p53 deficient mice (p53 (+/-) mice) of the CBA strain given a single dose of N-ethyl-N-nitrosourea (ENU). In order to clarify whether uterine tumors can be induced in transgenic mice carrying a human prototype c-Ha-ras gene (rasH2 mice) that are very susceptible to genotoxic carcinogens, rasH2 mice and their wild-type littermates received an intraperitoneal injection of 120 or 0mg/kg body weight of ENU followed by no further treatment for 22 weeks. Eighteen and 94% of ENU-treated rasH2 mice had uterine endometrial adenocarcinomas and atypical hyperplasias, respectively. Other malignant and benign tumors such as lung alveolar/bronchiolar adenomas and carcinomas, forestomach squamous cell papillomas and carcinomas, splenic hemangiomas/sarcomas, skin papillomas, malignant lymphomas and harderian gland adenomas were also observed in ENU-treated rasH2 mice. The result in the present study suggests that female rasH2 mice are very susceptible to uterine carcinogenesis, providing a useful model for ENU-induced uterine epithelial tumors.
[Show abstract][Hide abstract] ABSTRACT: To examine the utility of N-nitrosamines as initiators for a 26-week two-stage rat nasal carcinogenesis model, male F344 rats were treated with 2,6-dimethylaniline (DMA), possessing promoting potential for the rat nasal cavity, after initiation with 3 subcutaneous injections of 1500 mg/kg of N-bis(2-hydroxypropyl)nitrosamine (DHPN), 30 mg/kg of N-nitrosobis(2-oxypropyl)amine (BOP), or 30 mg/kg of N-nitrosopiperidine (NPIP). Histopathologically diagnosed nasal epithelial hyperplasias and tumors, including carcinomas, were induced with all three, with significant increase in the DHPN+DMA, BOP+DMA, and NPIP+DMA groups compared with the DHPN alone, BOP alone, and NPIP alone groups, respectively. These results strongly suggested that repeated subcutaneous injections of DHPN, BOP, or NPIP are useful for initiation in the present 26-week nasal carcinogenesis model.
No preview · Article · Jan 2002 · Journal of Toxicologic Pathology
[Show abstract][Hide abstract] ABSTRACT: To investigate the modifying effects of eugenol (EUG), a component of cigarette smoke, on lung carcinogenesis, male and female transgenic mice carrying the human prototype c-Ha-ras gene (rasH2 mice) were given a single intraperitoneal injection of 250 mg/kg urethane (UR) or saline, followed by a diet containing 6,000 ppm EUG or basal diet for 26 weeks. Their non-transgenic CB6F1 littermates (non-Tg mice) were also treated in the same manner. In both male and female rasH2 mice, alveolar/bronchiolar hyperplasias, adenomas and carcinomas were observed in all UR-treated groups. However, there were no significant intergroup differences in the incidences and multiplicities of these lesions between the UR alone and UR + EUG groups. In non-Tg mice, alveolar/bronchiolar hyperplasias, adenomas or carcinomas were sporadically observed in UR-treated groups of both sexes, with no significant differences in the incidences and multiplicities between the UR alone and UR + EUG groups. There were no intergroup differences between them in the PCNA-positive ratios of adenomas or carcinomas and the areas of adenomas or carcinomas to the whole lung area examined. The present results suggest that the EUG treatment does not exert modifying effects on lung carcinogenesis induced by UR in both male and female rasH2 mice and non-Tg mice.
No preview · Article · Sep 2001 · The Journal of Toxicological Sciences
[Show abstract][Hide abstract] ABSTRACT: To evaluate the transgenic mouse carrying a human prototype c-Ha-ras gene (rasH2 mouse) as a model for 26-week carcinogenicity tests, Di(2-ethylhexyl)phthalate (DEHP), a peroxisome proliferator, was administered to 15 rasH2 mice/sex/group at concentrations of 1,500, 3,000 or 6,000 ppm, and to 15 wild-type (non-Tg) mice/sex/group at a concentration of 6,000 ppm in their diets for 26 weeks. Survival rates and food consumption in the groups treated with DEHP and in the control group were similar. Body weight gain in rasH2 and non-Tg mice at 6,000 ppm in the terminal week decreased about 10% as compared to the control group. Common findings related to treatment with DEHP in rasH2 and non-Tg mice included hypertrophy with coarse granules and deposit of pigment in the liver, hydronephrosis and tubular regeneration in the kidney, focal atrophy in the testis, and increased eosinophilic body in the nasal cavity. Hepatocellular adenoma was induced by treatment with DEHP, and was confined to male rasH2; mice the incidence being 7%(1/15), 13%(2/15), and 27%(4/15) in the 1,500-, 3,000-, and 6,000-ppm group, respectively. Point mutation was not detected in codon 12 and 61 of human c-Ha-ras transgene upon DNA analyses on frozen samples taken from these hepatocellular adenomas. From the results obtained in this 26-week carcinogenicity study, it is concluded that DEHP is a hepato-carcinogen for transgenic mouse carrying a human prototype c-Ha-ras gene.
[Show abstract][Hide abstract] ABSTRACT: To cast light on whether xylazine hydrochloride (XZ), a veterinary medicine commonly used as a sedative agent for food-producing animals, has any promoting potential for thyroid carcinogenesis, the following studies were performed. In Experiment I, male F344 rats received a diet containing 1000 or 0 p.p.m. XZ for 52 weeks with or without initiation with 2400 mg/kg N:-bis(2-hydroxypropyl)nitrosamine (DHPN). Focal follicular cell hyperplasias, adenomas and/or carcinomas were induced in the DHPN alone, XZ alone and DHPN+XZ groups, and the incidences and multiplicities of these lesions in the DHPN+XZ group were significantly increased as compared with the DHPN alone case. In Experiment II, male F344 rats received a diet containing 1000 or 0 p.p.m. XZ and were examined for serum levels of triiodothyronine (T(3)), thyroxine (T(4)) and thyroid-stimulating hormone (TSH) at weeks 1, 2 and 4. In the XZ group, significant increase in thyroid weight and decrease in serum T(4) levels were observed at all time points. Serum T(3) and TSH levels were significantly decreased and increased, respectively, at week 1, but returned to within the control range thereafter. In Experiment III, male F344 rats received a diet containing 1000 or 0 p.p.m. XZ, they were examined for thyroid iodine uptake and organification of XZ after 1 and 2 weeks. The thyroidal iodine uptake per milligram of thyroid and the amount of iodine bound to 1 mg protein showed a tendency for decrease at week 1 and significant decrease at week 2. These results indicate that XZ has tumor-promoting effects on thyroid follicular cells, and suggest an involvement of alterations in thyroid-related hormone levels due to inhibition of thyroid iodine uptake and organification, resulting, provably, in serum TSH stimulation depending on continuous reduction of serum T(4) level through the feedback system in the pituitary-thyroid axis.
[Show abstract][Hide abstract] ABSTRACT: Proliferative lesions induced by 2,6-dimethylaniline (DMA) in a two-stage rat nasal carcinogenesis model were immunohistochemically and ultrastructurally investigated. Male F344 rats received diet containing 3,000 ppm DMA for 52 weeks after initiation with a single subcutaneous injection of 2400 mg/kg of N-bis(2-hydroxypropyl)nitrosamine (DHPN). Histopathologically, proliferation of Bowman's glands, glandular hyperplasias, dysplastic foci, adenomas, and carcinomas were observed in treated rats. These nasal lesions mostly arose in the olfactory mucosa of the nasal cavity. Immunohistochemically, they were positive for cytokeratin and/or collagen type IV antibodies. Ultrastructurally, intracytoplasmic dense secretory granules (200-850 nm in diameter), identical to those in normal Bowman's glands, were observed in all the lesions, providing further support from an origin from these glands. Based on their cellular characterization, growth pattern and/or proliferative activity, two morphological continua were evident, one from dysplastic foci to carcinomas and the other from proliferation of Bowman's glands to glandular hyperplasias and adenomas. These results suggest that dysplastic foci arise from Bowman's glands and progress to carcinomas, while proliferation of Bowman's glands result in glandular hyperplasias and adenomas.
Preview · Article · May 2001 · Toxicologic Pathology
[Show abstract][Hide abstract] ABSTRACT: To investigate the susceptibility of heterozygous p53-deficient CBA mice [p53 (+/-) mice] to promotion of liver proliferative lesions in a two stage hepatocarcinogenesis model, 30 p53 (+/-) mice and 30 wild-type littermates [p53 (+/+) mice] received an i.p injection of 5 mg/kg of N-nitrosodimethylamine (DMN), and from one week later, each group was given free access to drinking water containing 0.05 or 0 % of phenobarbital (PB) for 26 weeks. The final body weights were significantly decreased in both p53 (+/-) and p53 (+/+) mice of the DMN+PB compared to the DMN alone groups and the liver weights were significantly increased. The survival rate was 67 and 73% in p53 (+/-) and p53 (+/+) mice of the DMN+PB group, respectively, and there were no deaths in any of the mice receiving DMN alone. The incidences of eosinophilic foci in the liver (90 and 54.6% in p53 (+/-) and p53 (+/+) mice, respectively) in the DMN+PB groups were significantly higher than those with DMN alone (6.7% in p53 (+/-) mice, 0% in p53 (+/+) mice). The incidences of clear cell foci and hepatocellular adenomas were 10.0 and 9.1%, and 60.0 and 27.3%, respectively, in p53 (+/-) and p53 (+/+) mice receiving DMN+PB. These lesions were not seen in the DMN alone group. The PCNA labeling indices for eosinophilic foci and hepatocellular adenomas in the DMN+PB group were significantly higher in p53 (+/-) than in p53 (+/+) mice. The present results suggest that p53 (+/-) CBA mice are very susceptible to promotion of the development of liver proliferative lesions by PB after DMN initiation.
No preview · Article · Jan 2001 · Journal of Toxicologic Pathology
[Show abstract][Hide abstract] ABSTRACT: A novel rat model of hereditary renal cell carcinoma (RC) was found in a rat colony of the Sprague-Dawley strain in Japan, and named the rising "Nihon" rat. In this strain, RCs develop from early preneoplastic lesions, which begin to appear at 4 weeks of age, forming adenomas by the age of 16 weeks. The RCs are predominantly of clear cell type. Southern blot, northern blot and SSCP analyses revealed no change in the Tsc1, Tsc2, VHL, and c-Met genes. Thus, the Nihon rat should be a valuable experimental model for understanding renal carcinogenesis, especially clear cell type, which is common among human RCs.
Full-text · Article · Dec 2000 · Japanese journal of cancer research: Gann
[Show abstract][Hide abstract] ABSTRACT: Male F344 rats received diet containing 3,000 ppm 2,6-dimethylaniline (DMA) after initiation with a single subcutaneous injection of 2,400 mg/kg of N-bis(2-hydroxypropyl)nitrosamine (DHPN), and histological and electron microscopic examinations of the nasal cavity were performed at 4, 13, 26 and 52 weeks to examine sequential changes induced by DMA. Severe atrophy of Bowman's glands and epithelial disarrangement were apparent from week 4, followed by dilatation and/or proliferation of Bowman's glands, degeneration of epithelial cells, and proliferation of undifferentiated epithelial cells from week 13. Focal glandular hyperplasias, dysplastic foci, and adenomas were observed from week 26, and carcinomas at 52 week. These nasal lesions were mostly evident in the olfactory mucosa in the nasal cavity, and their severity and/or incidences, other than atrophy of Bowman's glands, increased with the treatment period. Electron microscopically, carcinoma cells demonstrated desmosomes, dense secretory granules identical to those in normal Bowman's glands, a basement membrane, and microvilli. These results suggest that Bowman's glands are the target of DMA, giving rise to nasal carcinomas after DHPN-initiation.
No preview · Article · Aug 2000 · Journal of Veterinary Medical Science
[Show abstract][Hide abstract] ABSTRACT: To cast light on whether the carcinogenic risk of 2,6-dimethylaniline (DMA), a metabolite of xylazine, may increase by ingestion of edible tissues from domestic animals treated with xylazine, the following studies of xylazine and DMA were performed. In Experiment I, male F344 rats received a single oral administration of 150 mg/kg of xylazine hydrochloride. Rats showed symptoms suggesting loss of sensation and pain immediately after the treatment. These signs had disappeared after 3 hr, but the animals died of hydrothorax and pulmonary edema by 9 hr. The plasma concentration of xylazine was 2.88 +/- 0.95 micrograms/ml at 15 min, and then decreased to 0.10 +/- 0.01 microgram/ml at 6 hr. The plasma level of DMA remained at 0.03 to 0.04 microgram/ml during the measurement period. In Experiment II, male F344 rats were fed a diet containing 1000 ppm of xylazine hydrochloride, regarded as the maximum tolerated dose, for 4 weeks. No clear clinical signs were evident and the plasma levels of xylazine and DMA were at the detection limit (0.02 microgram/ml) or less, although follicular cell hypertrophy of the thyroid was observed in all the treated animals. In Experiment III, male F344 rats were fed a diet containing 3000 ppm or 300 ppm of DMA for 4 weeks. Histological changes, such as atrophy of Bowman's gland and irregular arrangement of olfactory epithelial cells, were only observed in the olfactory epithelium of the 3000 ppm group. The plasma levels of DMA were 0.20 to 0.36 microgram/ml in the 3000 ppm group, but under the detection limit in the 300 ppm group. These results suggest that the probability of nasal carcinogenic effects of DNA on consumers via ingestion of edible tissues from food-producing animals treated with xylazine is extremely low, since DMA levels in the blood of rats subjected to continuous administration of high doses of xylazine remained under the detection limit.
No preview · Article · Jun 2000 · The Journal of Toxicological Sciences
[Show abstract][Hide abstract] ABSTRACT: To investigate the sensitivity of heterozygous p53-deficient CBA mice to carcinogens, 20 female mice [p53(+/-)] and 20 wild-type littermates [p53(+/+)] were given an intraperitoneal injection of 120 mg/kg body wt of N-ethyl-N-nitrosourea (ENU) and were maintained without any other treatment for a further 26 weeks. Histopathology showed that uterine tumors (endometrial polyps and stromal sarcomas) and lung adenomas were induced in both p53(+/-) and p53(+/+) mice. The incidence of uterine tumors and lung adenomas (94% and 81%, respectively) in p53(+/-) mice was significantly greater than that in p53 (+/+) mice (37% and 42%, respectively). Malignant lymphomas were only induced in p53(+/-) mice, at an incidence of 31%. Concerning uterine tumors and preneoplastic lesions, there were endometrial stromal sarcomas and atypical hyperplasias of the endometrial gland in 90% and 63%, respectively, of p53(+/-) mice, with significantly greater incidences than in p53(+/+) mice. Gene analysis revealed GCG-->GTG point mutations in codon 135 of exon 5 of the p53 allele in all of the uterine endometrial stromal sarcomas examined. Our results suggest that female p53(+/-) CBA mice are very susceptible to uterine carcinogenesis, providing a useful model for ENU-induced uterine tumors.