Monascus colour (MC) was administered to groups of 50 male and 50 female F344/DuCrj rats at levels of 2.5 and 1.25% in diets for 108 weeks. The results of urine and serum analysis, hematological determinations, and histological studies show that there was no significant difference between test and control rats. The incidence of spontaneous tumour was similar between test and control group. It was concluded that MC does not induce tumours when given orally to F334/DuCrj rats for 108 weeks.

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Male Syrian golden hamsters fed either vitamin A-free diet or normal stock diet with or without vitamin A supplementation were subjected to cigarette smoke inhalation for 6 weeks to study the relationship between the pulmonary cell response and vitamin A intake. All surviving animals after the last smoke exposure were killed for analysis of plasma and liver vitamin A contents and histopathology of the lung. Plasma and liver vitamin A levels were apparently lower in hamsters fed vitamin A-free diet than those maintained on normal stock diet. Liver vitamin A content was significantly higher in vitamin A-supplemented hamsters than those on stock diet alone, although there was no significant difference in plasma vitamin A level. Histopathologically, the number of free macrophages was counted in lung sections stained with hematoxylin and eosin and the count was used as the index to evaluate smoke-related insult at different levels of vitamin A. The number of macrophages was significantly greater in the smoke-exposed hamsters on vitamin A-free diet than those on normal stock diet. However, there was no significant difference in the macrophage count between vitamin A-supplemented and unsupplemented hamsters on stock diet. These results indicate that vitamin A deficiency and smoke exposure appear to enhance pulmonary macrophage mobilization. It is possible that the respiratory epithelium of vitamin A-deficient hamsters loses its integrity and becomes susceptible to injury by irritants such as those present in cigarette smoke. The elevated pulmonary free macrophage count may be a response to the damage caused by vitamin A deficiency and smoke exposure.

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This study was conducted to examine the histopathological and immunohistochemical changes of airways in guinea pigs repeatedly sensitized with aerosolized ovalbumin (OA) administered via an ultrasonic nebulizer. After the 10th exposure with OA, the guinea pigs were fully sensitized and showed the anaphylaxical changes, such as hemorrhage, emphysema, bronchoconstriction, and peri-bronchial and/or peri-vascular edema in the lungs. Furthermore, the increment of TUNEL and PCNA positive cells were detected among the alveolar epithelial cells, and a gradual increase of lymphocytes and eosinophils were found in the submucosa of the trachea and bronchus.
The pathogenesis of these lesions were not clear, but the morphological features recognized in this study were very similar to those of vascular leak syndrome induced by the administration of interleukin-2.

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Six-week-old male Mini rats were intraperitoneally given 1, 000mg/kg of D-galactosamine hydrochloride (GalN) once a week for 4 consecutive weeks and killed at 1, 2, 3, and 5 days (D) and 1, 2, 3, and 4 weeks (W) after the first GalN-administration, respectively. Proliferation of oval cells was observed at and after 3 D. Around them, prominent deposition of heparan sulfate proteoglycans was observed throughout the experimental period. Positive stainability for transforming growth facter (TGF)-β1 was detected in the cytoplasm of both bile duct epithelial cells in the Glisson's capsules and proliferating oval cells throughout the experimental period, and this may suggest an internalization of latent-type TGF-β1 in oval cells as well as bile duct epithelial cells. These results, in turn, indicate the differentiation of oval cells into bile duct epithelial cells. On the other hand, the number of Kupffer cells positive for ED2 peaked at 2D and thereafter decreased gradually, and no spacial relationship was detected between Kupffer cells and proliferating oval cells.

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The stomach region of male hypocatalasemic (C^b_s), C3H, and BALB mice of both sexes was irradiated once with a dose of 20 Gy of X-ray. After irradiation the C^b_s mice were administered with 0.1% hydrogen peroxide (H₂O₂) solution as their drinking water, or 10% sodium chloride (NaCl) in their diet. The resultant total tumor incidences were 50% to 100% by the end of the experiment after 13 months. More female mice died in the early phase after X-irradiation than males. Well differentiated tumors were observed in the glandular stomachs of 35 to 100% and signet ring cell carcinomas in 0 to 22% of the animals. Squamous cell carcinomas (SCCs) were most frequently encountered in BALB mice of both sexes. The present results indicate that X-ray induction of adenocarcinomas, signet ring cell carcinomas, and SCCs of the glandular stomach in CS mice is not promoted by H₂O₂ or NaCl.

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Wistar-Furth-Osaka (WF/Osp) rat strain has been considered to induce spontaneous gastrocolonic adenocar-cinoma. ACI rats, fosterbred from WF/Osp also developed the same type of colon adenocarcinoma. The serum from colon cancer-carrying rats induced the same tumors in Wistar/Shionogi (Wistar/Shi) rat strain, and the serum of which also induced analogous tumors in ACI rat strain by intraperitoneal injection at newborn period.
Negative staining on solid-phase immune electron microscopy study revealed numerous particles in the tissue culture medium of transplantable gastric carcinoma. To bring to light the infectious cell line, susceptible to colon cancer inducing virus was the consequential element to analyze transmissible agents. Using monoclonal antibody against colon cancer inducing virus, IF studies were carried out on all organs, mainly the chest, abdominal, and urogenital organs of cancer carrying WF/Osp rat. We found that the NBT-II cell line originating from the urinary bladder cancer cell is susceptible to gastrocolonic cancer inducing virus.

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The effect of hyperlipidemia induced by cholesterol (CHS)-feeding or Triton WR-1339 (Triton) injection on renal glomerular lesions in the streptozotocin (STZ)-induced diabetic rats was ultrastructurally studied. In non-diabetic and hyperlipidemic rats, mesangial cells contained electron-lucid vacuoles or droplets but showed no cellular proliferation or increase in type IV collagen and fibronectin positive areas. In STZ-diabetic rats, however, either with or without lipidemia mesangial cells were significantly increased in number, showing “mesangial interposition” between the capillary lamina densa and endothelial cells. The mesangial cells and the capillary basement membrane were positive for type IV collagen, and the former was also positive for fibronectin. Some mesangial cells were packed with a number of electron dense droplets or vacuolation, narrowing the capillary lumen. The basement membrane was thicker and type IV collagen- as well as fibronectin-positive areas were expanded in STZ-diabetic and hyperlipidemic rats.

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A simple method of preparing rat bladder epithelial cells for flow cytometry was developed, which involves the procedure of (1) eversion of urinary bladder, (2) dissociation of the urothelial cells from the underlying connective tissue using an enzyme cocktail (collagenase, dispase, and trypsin) and (3) subsequent treatment with EDTA. The use of trypsin was essential to remove erythrocytes from cell suspension. This method allowed us to obtain at least 5×10⁵ cells per bladder which were sufficient to measure DNA content distribution more than 10 times per animal. Despite use of trypsin, this method yielded DNA histograms with a sharp G₀/G₁-peak whose coefficient of variation was approximately 5%. The percentages of cells in G₀/G₁, S, and G₂/M phases (mean±standard deviation) were 96.0±1.3%, 0.5±0.1%, and 3.2±1.1%, respectively. Thus, the results indicate that this method in a good isolation procedure to obtain a number of single urothelial cells for flow cytometry.

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Immunolocalization of glutathione-peroxidase (GSH-PO) in the rat ventral prostate was investigated under the presence or absence of androgen. Male Sprague-Dawley rats were divided into four experimental groups. Group 1 consisted of intact controls. In group 2, rats were sacrificed two days after castration. In groups 3 and 4, rats were administered subcutaneously l mg/animal of testosterone-propionate daily for three or seven days after two days of castration. The intensity of GSH-PO staining in the glandular epithelial cells of the ventral prostate was remarkably decreased after castration (group 2), and that it was clearly recovered by testosterone-administration to the castrated rats (groups 3 and 4). Furthermore, the levels of the prostatic GSH-PO mRNA were remarkably diminished in the castrated rat ventral prostate (group 2), and that it was markedly increased by testosterone-administration to the castrated rats (groups 3 and 4). These findings strongly suggest that expression of GSH-PO in the glandular epithelial cells of the rat ventral prostate is considered to be testosterone-dependent.

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For histopathologic examination of the testis, it is necessary to classify the stage of spermatogenesis in seminiferous tubules (staging). Periodic acid-Schiff (PAS) stained sections are excellent for classiflying the stage because of distinct-stained acrosome in the round spermatid. HE stained sections are also suitable for brief classification of spermatogenesis into four groups (block). With both staining, however, evaluation of the sections is a difficult and time-consuming task even for well-trained workers. In this study, we applied the immunohistologic procedure using anti-proliferating cell nuclear antigen (PCNA) monoclonal antibody for staging germ cells in seminiferous tubules, and examined whether it was useful for histopathological screening of the testis. Ten normal testes from 7-week-old Wistar rats were ased for the study. These Bouin-fixed paraffin-embedded sections were treated with PCNA stain, PAS stain, and HE stain, respectively. In PCNA stained sections, the stages of seminiferous germ cells could be clearly classified into four groups by lower magnification than the other stains, and these groups coincided with each of the “block” classified by HE stain. Adding this, we tried to estimate drug-induced testicular toxicity by PCNA stain with testes obtained from Wistar rats administrated intravenously with adriamycin 6mg/kg. The obstruction of DNA synthesis was distinctively detected as focal lack of PCNA reaction in the spermatogonias. These findings indicate that PCNA staining is useful for the evaluation of the testis assisting the rapid classification of spermatogenesis and immunohistological diagnosis of testicular toxicity with DNA obstructive drug.

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The p53-deficient mice (Riken mice) were examined for tumors occurring spontaneously histopathologically and hematologically. Histopathologically, 87% of the males with tumors and 86% of the females with tumors had malignant lymphomas or lymphatic hyperplasia. It must be safe to say that more marked tendency to have spontaneous malignant lymphomas is seen in the p53-deficient mouse.

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