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Although a number of obesity animal models have been reported, each model possesses different characteristics of obesity, suggesting care should be taken in choosing an animal model suitable for the experimental purpose. In this report, we fed 4-(young) and 52-week-old (middle-aged) C57BL/6J (B6) and young BALB/cA (BALB/c) mice with a high fat diet (HFD) for 9 weeks, and investigated the clinical and histological characteristics of obesity. In BALB/c mice, males gained more body weight and body fat weight and had higher energy intake than females by HFD feeding. Comparing the effect of HFD feeding between the strains of mice, BALB/c male mice accumulated more hepatic lipid than B6 male mice. In addition, middle-aged B6 mice increased the ratio of fat to body weight and hepatic lipid accumulation more than young mice. In conclusion, the characteristics of obesity induced by HFD feeding were influenced by the sex, strain and age of mice. Sex steroid hormones, hepatic lipid metabolism and systemic metabolism might be involved in these factors. The basic data in this study will be useful for the development of animal models of high fat diet-induced obesity.

The fetal brain is susceptible to many extrinsic stresses. Some of these stresses induce excessive cell death in the prenatal stage, leading to anomalies in the neonatal brain. However, it is unclear how the developing brain responds to and repairs the prenatal tissue damage. We treated pregnant rats on day 13 of gestation with 5-azacytidine, one of the compounds that induces excessive cell death and inhibits proliferation in neural progenitor cells, to damage the fetal brain, and investigated the repair process up to 60 h after treatment. Histological analysis showed that 5-azacytidine induced strong apoptosis of neural cells. By 60 h, apoptotic cells disappeared and the tissue was repaired, although the telencephalic wall remained thinner than in controls. Flow cytometry analysis showed that the cell cycle distribution also returned to control levels at 60 h, suggesting that the repair process was completed around 60 h. During the repair period, amoeboid microglia infiltrated the brain and ingested the apoptotic cells. These microglial cells were positive for the multiple microglial markers, and mRNAs for the microglia-related cytokines tumor necrosis factor alpha, interleukin 1beta and macrophage colony stimulating factor (M-CSF) were up-regulated. DNA microarray analysis showed the up-regulation of genes relevant to glial cells, inflammation, the extracellular matrix, glycolysis, proliferation and neural development. We show here that the developing brain has the capacity to respond to the damage induced by extrinsic chemical stresses, including changing the expression of numerous genes and the induction of microglia to aid the repair process.

Mutation in the serum/glucocorticoid regulated kinase 3 (Sgk3, also known as Sgkl or Cisk) gene causes both defective hair follicle development and altered hair cycle in mice. We examined Sgk3-mutant YPC mice (YPC-Sgk3ypc/Sgk3ypc) and found expression of SGK3 protein with altered function. In the hair follicles of YPC mice, the aberrant differentiation and poor proliferation of hair matrix keratinocytes during the period of postnatal hair follicle development resulted in a complete lack of hair medulla and weak hair. Surprisingly, the length of postnatal hair follicle development and anagen term was shown to be dramatically shortened. Also, phosphorylation of GSK3β at Ser9 and the nuclear accumulation of β-catenin were reduced in the developing YPC hair follicle, suggesting that phosphorylation of GSK3β and WNT-β-catenin pathway takes part in the SGK3-dependent regulation of hair follicle development. Moreover, the above-mentioned features, especially the hair-cycling pattern, differ from those in other Sgk3-null mutant strains, suggesting that the various patterns of dysfunction in the SGK3 protein may result in phenotypic variation. Our results indicate that SGK3 is a very important and characteristic molecule that plays a critical role in both hair follicle morphogenesis and hair cycling.

5-Azacytidine (5AzC) is a cytidine analogue which possesses nitrogen atom instead of carbon atom at the position 5 of the pyrimidine ring. In this study, detailed histopathological changes were sequentially examined in the rat fetal brain obtained from dams treated with 5AzC (10 mg/kg) on day 13 of gestation (GD13). At 6 hours after treatment (HAT), a prominent accumulation of neuroepithelial cells showing pleomorphic mitotic figures were observed in the telencephalic wall. The mitosis-index peaked at 6 HAT, and decreased thereafter. Neuroepithelial cells positive for nick end labeling (TUNEL) method, which is widely used for the detection of apoptotic cells, prominently increased at 9 HAT, and the TUNEL-index peaked at 12 HAT. TUNEL-positive cells showed ultrastructural characteristics of apoptosis. At 24 HAT, the formation of rosette-like structures was observed in the fetal brain. From the results of the present study, it was evident that abnormal mitosis and neuronal apoptosis were induced in the rat fetal brain following 5AzC-administration to dams on GD13. In addition, it is suggested that 5AzC-induced apoptosis might occur mainly in the post mitotic phase of cell cycle.

Early ultrastructural changes in the dorsal skin epidermis of Wistar-derived hypotrichotic WBN/ILA-Ht rats were examined for up to 12 hours after UVB-irradiation (10 kJ/m2) (12 HAI). The first change appeared at 3 HAI as swelling and/or vacuolation of mitochondria in the spinous and basal cells. The number of keratinocytes with such mitochondrial changes decreased thereafter. At 6 HAI, apoptosis of basal cells developed. These cells showed shrinkage of cell bodies with condensed or fragmented nuclei and dark cytoplasm due to densely packed bundles of tonofilaments. At the same time, keratinocytes with prominent nucleoli were also observed in the basal and suprabasal layers. At 12 HAI, the number of keratinocytes with prominent nucleoli increased, and mild and focal intercellular edema developed mainly in the basal layer. In addition, a small number of apoptotic basal cells were still observed. The present ultrastructural findings supported the histopathological findings previously reported by our research group.

This study was designed to examine the preventive effect of a novel endothelin (ET)-receptor antagonist TA-0201 on the cerebral vasospasm in a canine double-hemorrhage model. TA-0201 (10 -9 -10 -7 M) inhibited ET-1-induced vasoconstriction in the isolated canine basilar artery without endothelium in a concentration-dependent manner. Its pA 2 value was 9.2 (ET A antagonism). In a canine double-hemorrhage model, intravenous treatment with TA-0201 (3 mg/kg, twice a day for 7 days) ameliorated the basilar artery narrowing significantly on day 7 compared with that in nontreated dogs. The reductions of the basilar artery diameter were 26.1 ± 3.9% and 40.5 ± 4.1% with and without TA-0201 treatment, respectively (p < 0.05). Histologic study on day 7 indicated that treatment with TA-0201 inhibited vessel-wall damage such as disintegration of endothelium architecture and degeneration of medial smooth-muscle cells. We conclude that intravenous treatment with TA-0201 prevents the development of cerebral vasospasm and accompanying pathologic changes of the vessel wall, probably through blockade of ET A receptors.

TA-993 is a novel 1,5-benzothiazepine derivative of l-cis configuration, having a potent antiplatelet action and an increasing action on femoral blood flow. We evaluated the antithrombotic effect of TA-993 in a canine model of femoral arterial thrombosis. Thrombus was induced by both application of direct anodal current to the femoral artery and partial occlusion of the artery. The partial occlusion by placing an adjustable occluder on the artery and the current application were carried out 40 and 60 min after the intraduodenal administration of drugs, respectively. In control dogs, complete sustained occlusion of the femoral artery due to thrombus occurred 55.4 +/- 9.2 min after the onset of current application. TA-993 (3 and 10 mg/kg) dose-dependently prolonged the time for occlusion. Aspirin (30 mg/kg) also prolonged it. TA-993, 10 mg/kg, significantly inhibited whole-blood aggregation 60 min after the administration with a weaker potency than that of aspirin (30 mg/kg), whereas 3 mg/kg of TA-993 did not. The inhibitory effect of TA-993 (10 mg/kg) on platelet aggregation was maintained for >7 h. Moreover, TA-993 (10 mg/kg) increased femoral blood flow in spite of the partially occluded condition. These results indicate that TA-993 has an antithrombotic effect on femoral arterial thrombosis and suggest that an increasing action on femoral blood flow of TA-993 is more relevant than its antiplatelet action to the antithrombotic effect in this model.

Summary Morphological examinations were carried out on hepatocyte nuclei of streptozotocin (SZ)-induced diabetic mice. The area of hepatocyte nuclei in diabetic mice was about two times larger than that in control mice, and the incidence of hepatocytes with intranuclear inclusions was 3.4 ± 0.2% in diabetic mice and 0% in control mice, respectively. Although the incidence of binuclear hepatocytes was not significantly different between diabetic (14.5 ± 4.6 %) and control mice (16.4 ± 4.4 %), the morphology of the nuclei of binuclear hepatocytes was apparently different between diabetic and control mice. Namely, the nuclei of binuclear hepatocytes of control mice were round and identical in ultrastructural appearance, and they did not differ from those of mononuclear diploid hepatocytes. On the other hand, the nuclei of binuclear hepatocytes of diabetic mice were not identical in distribution pattern of chromatin granules, and they frequently varied in size and showed irregular contours.

Light and electron microscopic examinations were carried out on the dorsal skin to which hydrogen peroxide (HPO) (3, 6, and 10%) was topically applied for 7 consecutive days in Wistar rat-derived inbred WBN/Kob-Ht rats which have an autosomal dominant gene responsible for their characteristics of hypotrichosis. In addition to focal epidermal thickening, keratinocyte necrosis, dermal mononuclear cell infiltration and focal detachment of the epidermis from the dermis by fluid-filled spaces were detected. This is thought to be brought about by edema due to prominent capillary endothelial damage in the superficial dermis. The damage to keratinocytes and capillary endothelial cells was thought to be induced by HPO itself and free radicals generated by HPO. In addition, these changes were apparently more severe in WBN/Kob-Ht rats than in Wistar rats used as controls.

Tumors at the cranial base in 2 cats (a 9 1/2-year-old, castrated male Chinchilla and a 7-year-old, castrated male American shorthair) were diagnosed as malignant craniopharyngioma. The tumor lesion was histopathologically divided into four parts: 1) a small acinus part, in which relatively large cells with a pale cytoplasm composed small acini; 2) a duct part, in which small cuboidal cells composed ducts; 3) a cyst part, in which there were large cysts lined with flat cells; and 4) a pavement part, in which large multiangular-shaped cells proliferated in a pavement pattern. The epithelial cells of some parts were positive for keratin by immunohistochemistry. Histopathologic findings of the present feline cases were identical to those of malignant craniopharyngioma in other animal species.

A 12-year-old male Shiba dog showed anemia and the swelling of systemic lymph nodes. X-ray and post mortal examinations revealed a anterior mediastinal mass. Histologically, the tumor mass consisted of four different elements; cord-like proliferation of cuboidal epithelial cells, tubular or cystic structures lined with ciliated epithelial cells, proliferation of large round-shaped epithelial cells with PAS-slightly positive granular cytoplasm, and diffuse proliferation of neoplastic lymphocytes. Epithelial cells in cord-like or cystic structures were strongly positive for cytokeratin. Granular or foamy cells were negative for all markers examined and had myelin-like bodies in the cytoplasm by electron microscopy. The neoplastic lymphocytes in the tumor mass were considered being derived from concurrent multicentric lymphoma. Based on these findings, the present case was diagnosed as thymoma with a part of granular cell proliferation and concurrent lymphoma cells.

Since reported experimental models of thrombosis are not suitable for comparison of several drugs by oral administration, we developed a convenient model for this purpose by applying direct current through an intravascular electrode. In conscious rats, which were implanted with anodal electrodes in the abdominal aorta on the day before the experiment, application of 200 microA of direct current induced the formation of a platelet-rich thrombus around the intravascular electrode. Using this model, we studied the antithrombotic effect of the novel antiplatelet agent TA-993, (-)-cis-3-acetoxy-5-(2-(dimethylamino)ethyl)-2,3-dihydro-8-methyl-2-(4- methylphenyl)-1,5-benzothiazepin-4(5H)-one maleate, and compared its effect with other antiplatelet agents. TA-993 at doses of 30 mg/kg, p.o. or more by single administration or at doses of 10 mg/kg or more by repeated administration dose-dependently suppressed the thrombus formation. Aspirin (10 mg/kg, p.o. or more), cilostazol (100 mg/kg, p.o.) and ticlopidine (30 mg/kg, p.o. or more) also suppressed the thrombus formation by single administration. These results suggest that TA-993 has a comparable antithrombotic effect with other antiplatelet agents, and thus it is a possible remedy for thrombotic and embolic diseases.

Rabbits were fed with two kinds of atherogenic diet, one containing 0.5% cholesterol and 3% soybean oil and the other 0.5% cholesterol and 6% peanut oil, for three months to compare the atherogenic property of the diets. The soybean oil diet seemed to be superior to the peanut oil diet for evaluation of the anti-atherogenic effect of drugs, because the former caused milder vascular lesions than the latter. Using this rabbit model for atherosclerosis, the anti-atherogenic effect of clentiazem, a new calcium antagonist, was examined. Clentiazem at an oral dose of 30 mg/kg/day significantly reduced the size of atheromatous lesion in the aortic arch and thoracic aorta, and lowered the collagen content of the aortic intima and media, although it did not decrease serum lipid levels. On the other hand, clentiazem showed no clear effect on reducing the coronary atherosclerotic lesions. These results suggest that clentiazem may inhibit the progression of diet-induced aortic atherosclerosis without normalizing the serum lipid levels.

A 6-year and 9 month-old, male, Shih Tzu dog showed ataxia and trembling. By MRI examination, a mass (1 cm) was found in the right cerebellum. As the dog did not respond to radiation therapy, and showed a rise of intracranial pressure, he was euthanized. The cerebellar mass was soft and hemorrhagic. Histologically, the mass contained vimentin-positive spindle- or polyhedral-shaped cells arranged in a cord-like pattern. Mucinous materials were observed in the intercellular spaces. Ultrastructural examination revealed cell processes, microtubule-like structures and desmosomes. The case was diagnosed as myxoid type meningioma.

Effects of ecabet sodium (TA-2711), a locally acting antiulcer agent, on prostanoid production and the morphology of the rat gastrointestinal mucosa were studied in comparison with sucralfate. Ecabet, at therapeutic doses (25 and 100 mg/kg, p.o.), dose-dependently increased the gastric mucosal level of prostaglandin E2 (PGE2) : sucralfate (100 mg/kg, p.o.) showed a tendency to increase the PGE2 level. In an ex vivo study, ecabet (25 and 100 mg/kg, p.o.) dose-dependently increased the capacity of the gastric mucosa to synthesize PGE2 and PGI2 without modifying tromboxane A2 (TXA2) synthesis, and the 100 mg/kg dose persisted for up to 3 h. Ecabet (400 mg/kg, p.o.) also significantly increased PGE2 synthesis and there was a tendency to increase PGI2 synthesis by the duodenal mucosa, without affecting TXA2 synthesis. PGE2 synthesis by the colonic mucosa was not affected, even at a high dose of ecabet (1000 mg/kg, p.o.). When the rat gastric mucosa was examined by light microscopy and scanning electron microscopy, ecabet (100 and 400 mg/kg, p.o.) had caused no morphological change to the gastric mucosa, while sucralfate (100 and 400 mg/kg, p.o.) produced apical rupture of the epithelial cells and subepithelial edema. The present study indicates that ecabet locally stimulates PGE2 and PGI2 production in the gastroduodenal mucosa and this effect is not attributable to a local irritant action accompanied by superficial epithelium damage.

Female Swiss mice were treated for 24 weeks, with 3-hydroxy-4-pyrone (Py) added to their powdered diet at 0.5% (wt/wt), and the effects of this agent on the liver were examined. Serum transaminases (especially GPT) rose continuously, while the GOT/GPT ratio remained at approximately 1.0 throughout the study period. The characteristic changes found from 8 weeks onward were piecemeal necrosis and bridging necrosis of the hepatocytes with dense lymphocytic infiltration. Proliferation of collagen fibers in the portal tracts and formation of narrow fibrous septa dividing the lobules into pseudolobules were also noted from 12 weeks onward. A large number of the infiltrating lymphocytes were identified as T cells by immunohistochemical and electron microscopic studies. These lymphocytes often surrounded or were closely attached to degenerating hepatocytes. Focal apoptosis and necrosis accompanied by a granulomatous reaction of the centrilobular hepatocytes were noted as early changes in the liver. Our findings indicate that the hepatic changes produced in mice by long-term Py administration have characteristics in common with those of human chronic active hepatitis. Immunological cytotoxic mechanisms, especially T cell-mediated ones, appear to play an essential role in the development of hepatic lesions in this murine model of chronic active hepatitis.

Rare cases of thymic granulomatous lesions were found in pigs. The lesions consisted of epithelioid cells, multinucleated giant cells, and lymphocytes. Such lesions also were observed in the mesenteric lymph nodes, spleen, kidney, and stomach. The cytoplasm of the majority of giant cells and some epithlioid cells was periodic acid-Schiff (PAS) positive. All cells were positive for vimentin, lysozyme, and desmin. Ultrastructurally, the giant cells were rich in organella and attached to adjacent epithelioid cells by membrane interdigitation. The cells included numerous coated vesicles and granules. No etiologic pathogen, including porcine circovirus type 2, was detected in the lesions. This is the rare case of idiopathic thymic granulomatous lesion in pigs.

The histopathological characteristics of Ito cells and Kupffer cells were investigated in the liver of 21 cats (age range: 6 months -18 years) autopsied in our laboratory during 2003. Immunohistochemical examinations were performed using antibodies against lysozyme, desmin and alpha-smooth muscle actin. No Kupffer cells reacted with the antibody against lysozyme. However, macrophages in the lung and spleen showed a positive reaction with the antibody. This finding suggests a possibility that the amount of lysozyme in the Kupffer cells of feline liver is comparatively small. On the other hand, large vacuole-laden cells were observed in the hepatic perisinusoid of some feline cases, and these cells showed a positive reaction with antibodies against desmin and alpha-smooth muscle actin. These cells could be Ito cells with large lipid vacuoles. This conclusion was supported by electron microscopic observation and oil red O staining. However, no such large vacuole-laden perisinusoidal cells were detected in the liver of young cats less than 2 years old. The present study revealed the histopathological features of Kupffer cells and Ito cells in the feline liver.

Mutation in the serum/glucocorticoid regulated kinase 3 (Sgk3, also known as Sgkl or Cisk) gene causes both defective hair follicle development and altered hair cycle in mice. We examined Sgk3-mutant YPC mice (YPC-Sgk3(ypc)/Sgk3(ypc)) and found expression of SGK3 protein with altered function. In the hair follicles of YPC mice, the aberrant differentiation and poor proliferation of hair matrix keratinocytes during the period of postnatal hair follicle development resulted in a complete lack of hair medulla and weak hair. Surprisingly, the length of postnatal hair follicle development and anagen term was shown to be dramatically shortened. Also, phosphorylation of GSK3beta at Ser9 and the nuclear accumulation of beta-catenin were reduced in the developing YPC hair follicle, suggesting that phosphorylation of GSK3beta and WNT-beta-catenin pathway takes part in the SGK3-dependent regulation of hair follicle development. Moreover, the above-mentioned features, especially the hair-cycling pattern, differ from those in other Sgk3-null mutant strains, suggesting that the various patterns of dysfunction in the SGK3 protein may result in phenotypic variation. Our results indicate that SGK3 is a very important and characteristic molecule that plays a critical role in both hair follicle morphogenesis and hair cycling.

Development of acinar cell apoptosis and ultrastructural changes in the exorbital lacrimal and parotid glands was examined in DBA/2 mice infected with 10(2) PFU/mouse of EMC-D virus. Pyknotic acinar cells, most of which were positive for TUNEL and cleaved caspase-3 and had ultrastructural characteristics of apoptotic cells, developed earlier and were more frequently observed in the parotid gland than in the exorbital lacrimal gland, while the total damage of acinar cells and interstitial infiltration of macrophages were more prominent in the latter than in the former. These findings indicate that EMC-D virus induces acinar cell apoptosis in these glands. In addition, corresponding to the results of the detection of viral RNA signals by in situ hybridization, small aggregates of virus-like particles having typical size and structure of EMC virus were frequently observed in both the cytoplasm and the nucleus of acinar cells in the exorbital lacrimal gland, while they were found only in the cytoplasm of a few acinar cells in the parotid gland. In conclusion, between the exorbital lacrimal and parotid glands, there was a reverse relationship observed between the development of acinar cell apoptosis and that of total damage of acinar cells.

Ultrastructual characteristics of the dorsal skin responses to a single irradiation of UVA (1100 kJ/m2) were examined in Wistar-derived hypotichotic WBN/ILA-Ht rats (HtRs). In the epidermis, mitochondrial swelling of some keratinocytes and dissociation of keratinocytes due to intercellular edema developed at 3 hours (h) after irradiation and continued to 48 h. At 6 h, in addition to these changes, necrosis of keratinocytes accompanied with infiltration of neutrophils was also observed in some portions, and epidermal hyperplasia with many keratinocytes showing nucleolar hypertrophy and some mitotic keratinocytes was observed at 48 h. In the dermis, mitochondrial swelling and/or partial cytoplasmic destruction in capillary endothelial cells and edema with inflammatory cell infiltration were observed at and after 3 h, and extravasation of erythrocytes was found in some capillaries at 48 h. Mitochondrial swelling was also frequently found in pericytes and fibroblasts. Inflammatory cells were mainly composed of neutrophils throughout the experimental period. Mild degranulation of mast cells which also showed mitochondrial swelling was observed at and after 3 h, and a close special relationship between mast cells and fibroblasts or neutrophils was sometimes observed. In conclusion, the most prominent change in the dorsal skin of HtRs exposed to UVA was degeneration of capillary endothelial cells, resulting in edema and inflammatory cell infiltration, and the most characteristic cytopathic effect of UVA was mitochondrial swelling, and it was common to keratinocytes, capillary endothelial cells, pericytes, mast cells, and fibroblasts.

The N-methyl-D-aspartate receptor (NMDAR), which is one of the glutamate receptors, is considered to have a close relation to synaptic plasticity in the developing brain. In addition, it is also known that the excessive stimulation of NMDARs can trigger neuronal apoptosis. In this study, we examined the expression of neuronal apoptosis in the developing rat brain after the administration of NMDA to pregnant dams or neonates (embryonal days 18 to postnatal days 14). In the NMDA-treated group, the significant increase in nuclei of apoptotic neuronal cells occurred in the dose-dependent manner in the lateral-ventral regions of the fetal cerebral cortex, reaching maximum values at 24 hours after treatment. On the other hand, the induction of apoptosis did not occur in the neonatal brain.

Mast cells are one of the major effector cells in the pathogenesis of allergic diseases such as contact dermatitis. In the present study, ultrastructural features of mast cells in contact dermatitis were examined. Namely, the ear of IQI/Jic mice was topically applied with picryl chloride (PCL) at 4 (1st), 11 (2nd), 18 (3rd) and 25 days (4th) after the sensitization with PCL to the abdominal skin. The changes in the ear swelling responses, total serum IgE levels and histology including mast cell numbers were similar to those of previous reports by our research group (Ikeda et al. 2000; Jung et al. 2001). Ultrastructurally, after the 1st application, a close spacial relationship between mast cells and neutrophils and phagocytosis of mast cell granules by neutrophils were observed. Mast cells generally contained non-fused swollen granules filled with altered contents with low electron density and showed an extrusion of membrane-free granules through membrane pores. In addition, interestingly, a few mast cells secreted membrane-bound granules into the dermis without leaving cell membrane damage. After the 4th application when the number of mast cells prominently increased and the total serum IgE level was greatly elevated, in addition to mast cells showing typical anaphylactic degranulation, many mast cells probably in the recovery process from degranulation and several immature mast cells characterized by well-developed Golgi apparatus, many ribosomes and a few electron-dense secretory granules in the peripheral cytoplasm were also observed at the same time. The present results clarified the ultrastructural features of mast cells in the course of PCL-induced contact dermatitis in IQI/Jic mice.

Summary Ultrastructural changes in the dorsal skin were examined in Wistar-derived hypotrichotic WBN/ILA-Ht rats exposed to subchronic UVB-irradiation (10 kJ/m2 per rat per day for up to 3 months). Epidermal hyperplasia developed at 1 month of UVB-irradiation and progressed thereafter, resulting in epidermal thickening and formation of epidermal ingrowths projecting into the dermis. In some portions of the epidermal ingrowths at 2 and 3 months, keratinocytes were somewhat pleomorphic. In addition, some of the keratinocytes showing cytoplasmic projections migrated into the dermis. The basement membrane and hemidesmosomes at the epidermal-dermal junction became to disappear along with the development of edema spreading from the upper dermis to the epidermis. However, Langerhans cells were still detected in the hyperplastic epidermis even at 3 months. In the dermis, in addition to edema, fibroblast proliferation and mast cell infiltration progressed with time, and degranulation of mast cells was obvious at 2 and 3 months. Only a few basophils as well as eosinophils were also found. In the upper dermis, especially beneath the epidermis, decrease in diameter and disintegration of collagen fibrils were observed. Ultrastructural characteristics of the dorsal skin responses to subchronic UVB-irradiation were clarified in the present study.

Pathological observation was carried out on 3 domestic cats spontaneously infected with Dirofilaria immitis. Principal lesions were found in a small number of pulmonary arterial branches which corresponded roughly to the site of parasitic infection. Marked degenerative and exudative changes involving the whole layers of the vascular wall and perivascular loose connective tissues were conspicuous in large pulmonary arterial branches containing embolic dead parasites. A certain causal relation may present between disorganized dead parasites and severe necrotic changes.

Changes of acute phase of atherosclerosis were studied in rats loaded witha mixture of massive doses of vitamin D. and cholesterol by a simple method similar toAltmans. Preferential sites of calcification and degeneration were observed in the vascularsystenn and parenchymal tissues. In the aorta, marked ca1cifica[ion and degeneration wereseen in the elastic membranes autd smooth muscle cells of the tunica media. At the sametime, an apparent accumulation of lipid droplets was recognized in the calcified and degenerated medial areas. On the other hand, in such muscular arteries as those of thecoronary arterial system wI?ich had undergone marked medial necrosis, lipid depositionwas very slight, if any, in most cases. Reparative changes occurred in affected blood vesselsshortly after the start of vitamin D.-loading. In the organs other than the arterial system, S(XCI( parenchymal degeneration and calcification were observed in the heart, kidneys, stomach, intestine and lungs, and only slight changes in the liver, spleen, pancreas, choroidplexus and adrenals.

Electron microscopic observation was carried out on the aortic arch of spontaneously hypertensive rats (SHRs) treated with high-cholesterol diet-feeding and vitamin D2-loading. In the control SHRs, intimal and medial thickening probably responsible to persistent hypertension was observed. The upper subendothelial portion of the thickened intima consisted primarily of densely packed basement membrane-like materials while the deeper portion mainly of abundant elastic fibers accompanying so-called modified smooth muscle cells (SMCs). Medial thickening appeared to be brought about by increase in collagen and elastic fibers around modified SMCs. On the other hand, in the treated SHRs, the almost all areas of the thickened intima were occupied by abundant elastic fibers and SMCs and therefore it exhibited appearance of more mature fibromuscular thickening in comparison with that of the control SHRs. Necrosis and destruction of SMCs with calcification were observed in the media and interstitial collagen and elastic bundles around calcific mass were loosened and dissociated with deposition of lipids, calcium salts and cellular debris.

Electron microscopic observation was carried out on the abdominal aorta and coronary artery of rats fed an atherogenic diet (containing 3% cholesterol, 1% cholic acid, 0.3% thiouracil and 21% hydrogenated fat) for 28 days combined with oral administration of vitamin D2 (320000 IU/kg/day) for the initial 4 days. Although the changes found in these two different types of artery were essentially similar to each other and characterized by the presence of lipid containing foam cells especially in the intima, some differences were detected between these arteries. Namely, deposition of fine fibrillar and granular materials, appearance of extracellular lipid crystals and increase in number of modified smooth muscle cells were apparent in the coronary artery, while increase in number of lipid-laden smooth muscle cells was conspicuous in the abdominal aorta. In addition, the present study demonstrated the possibility of transformation of both the smooth muscle cell and monocyte into foam cell.

Histopathological investigation of the distribution and characteristics of the lesions in beagle dogs given excessive vitamin D2 was undertaken with special attention to changes in the vascular system. At the same time, the effects of simultaneous cholesterol loading upon these lesions were also examined. Oral administration of vitamin D2 at the dose of 480, 000 I.U./kg/day for 21 days produced medial edema, disorganization of the elastic laminae and degeneration of smooth muscle cells in the aorta, and intimal edema, disruption of calcified internal elastic lamina and proliferation of smooth muscle cells in the coronary arteries. Metastatic calcification was observed in the lungs, trachea, kidneys, thyroid glands, parathyroid glands, choroid plexus, submandibular and parotid glands, prostate, stomach and retina. Simultaneous cholesterol loading at the dose of 300 mg/kg/day showed an additional deleterious effects on these changes, leading to the so-called Monckeberg's type sclerosis in the aorta characterized by the complex deposition of calcium, polysaccharides and a little amount of lipids in the media.

Pathological observations were carried out on 100 male rats of Sprague-Dawley strain obtained from 5 outbreaks of sialodacryoadenitis (SDA). In accordance with clinical and macroscopic findings, principal microscopic changes were found in the salivary (submaxillary and parotid) and Harderian glands. Lesions observed in these different glands were essentially similar to each other, and characterized by degenerative changes in the epithelial cells of the ducts and acini associated with marked and extensive serous inflammation in the interstice. Furthermore, squamous metaplasia of the ductal epithelia was a common feature to these glands in the late stage of the disease. Some differences, however, were detected between the changes of the salivary glands and those of the Harderian glands. Firstly, the ductal epithelial cells were affected at first and the acinous epithelial cells were damaged only secondarily in the active inflammatory process in the salivary glands, while both ductal and acinous epithelial cells were involved equally in the primary lesion in the Harderian glands. Secondly, the increase in connective tissue elements in the reparatory process was extremely marked in the Harderian glands as compared with the salivary glands. Consequently, in the lesion of Harderian glands in the late stage, original construction was almost indiscernible, and the ducts and acini were only recognized as disseminated islets in actively proliferated connective tissue elements.

Pathological observations were made on male Sprague-Dawley rats which had received intraperitoneal injections of sterile swine serum twice a week for 12 weeks. Changes were found mainly in the liver, kidneys and spleen. In the liver, pseudolobules were formed in all animals after 8 or more weeks. Proliferation of collagen fibers was detected first around the central veins and in the portal tracts after 3 weeks, and then in the space of Disse. After 8 or more weeks, numerous fat-storing cells (Ito's cells) were found in the collagen septa subdividing the lobules. In the initial stage of fibrosis, infiltration of eosinophils and mast cells was observed around the central veins and in the portal tracts. There were no noticeable changes, however, in hepatocytes or sinusoidal lining cells throughout the experimental period. In the kidneys, fine electron-dense deposits were found in the mesangial area of glomeruli after 4 or more weeks. In the corresponding sites, specific fluorescence of rat IgG was detected by the immunofluorescence technique. In the spleen, swelling and increased lymphatic follicles with active germinal centers were noticed after 2 or more weeks.

An outbreak of canine parvovirus infection in a group of 26 beagles was described. The disease characterized by acute intestinal involvement was highly contagious but fatality was low (1/26). Transient leukopenia was recorded in some animals. All the convalescent sera were positive in agar gel diffusion test using feline panleukopenia virus antigen. Histopathological examination on fetal dog revealed regressive change associated with formation of amphophilic intranuclear inclusion bodies in the enterocytes of the Lieberkuhn's crypt and regressive change in the lymphoid tissues. Pathologic picture exhibited strikingly resemblance with that of feline panleukopenia.

Pathogenic agents were isolated from affected salivary glands of rats with sialodacryoadenitis (SDA) by means of intercerebral inoculation to newborn mice and inoculation to primary rat kidney cell cultures. The properties of these isolates, irrespective of the isolation techniques, were in general agreement with that of SDA virus strain 681, and they were identified as SDA virus. In addition to the known properties, following characteristics were noticed: (1) Particles of SDA virus bore two different long and short surface projections. (2) Some antigenic differences were observed between the present isolate 930-10 and the strain 681. (3) It was suggested that SDA virus grew better at 35 degrees C than at 31 degrees, 33 degrees, 37 degrees or 39 degrees C. (4) SDA virus did not propagate in DBT cells.

Electron microscopic observation was carried out on epithelial cells of Lieberkuhn's crypts in the natural case of canine parvovirus infection. The replication of virions was revealed in the nuclei of the lining epithelial cells, as demonstrated in feline panleukopenia. In cells seemingly in the early stage of infection, virus particles 18 to 20 nm in diameter were scattered in swollen nuclei. In rather severely infected cells, the nuclei were considerably atrophic with a marked margination of chromatin granules and occupied with fine fibrillar masses and virion clusters. The nuclei of epithelial cells desquamated into the lumen were shown to have compact crystalline arrays of virions. Virions were observed also in the cytoplasm, being either membrane-associated or free in the ground substance.

Occurrence of coronavirus-like virions and associated degenerative changes were seen in the enterocytes of jejunal villi of a mongrel dog which had been diagnosed first as canine parvoviral disease from virological and pathological examinations. A cytopathic agent was isolated in dog kidney cell cultures from intestinal contents of the present case. The isolate, Toda strain, had morphological and physicochemical properties in common with the viruses of the coronavirus group. Toda strain was neutralized by ascites obtained from a cat with feline infectious peritonitis. Thus the case was diagnosed precisely as the mixed infection of canine parvovirus and canine coronavirus.

The livers of the male ddY mice having received repeated intraperitoneal injections of sterile swine serum were examined pathologically. The characteristic changes were eosinophilic and homogeneous or needle-shaped materials in the cytoplasm of biliary epithelial cells. Electron microscopically, the homogeneous material appeared moderately electron dense and amorphous being deposited in remarkably dilated rough-surfaced endoplasmic reticulum, while the needle-shaped one was quadrate in overall shape showing striated crystalline arrays at high magnification.

アジュバント病を好発するSprague-Dawley系の雄ラットと,野外発生の豚丹毒罹病豚から分、離したA型およびB型の豚丹毒菌の組み合せで,接種実験を行った.豚丹毒菌の接種によV),接種経路や豚丹毒菌の血清学的な型に関係なく,ラットに全身性症状を背景とした多発性関節炎を主徴とする豚丹毒菌感染症が成立した.多発性関節炎の発生率および死亡率の検討から,宿主ラットの週令,接種菌量および経路,ならびに血清型の違いは,本症の成立にもっとも重要な因子であることを認めた.