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Biomedical subjects

A Shiga

Publications and source records attributed to A Shiga.

At least 19 recordsLinked to original sources
PubMed1998

Study on the pathogenesis of porcine serum-induced liver fibrosis in rats with special reference to the effects of hypertension.

To investigate the pathogenesis of porcine serum (PS)-induced liver fibrosis in rats, two experiments were carried out, taking into consideration of hypertension and vascular changes. In Experiment I, spontaneous hypertensive rats (SHRs), two-kidney, one clip hypertensive F344 rats (2K1C rats), and normotensive F344 rats were given an intraperitoneal injection of PS of 0.5 ml twice a week for 8 weeks. Histopathological, immunohistochemical, and electron microscopical examinations were performed on the liver from each rat. Histological features of liver fibrosis in hypertensive and normotensive rats were essentially identical. However, in the PS-treated SHRs, 2 of 5 animals showed the most severe fibrosis in all PS-treated groups. Electron microscopically, degranulated mast cells, eosinophils, and macrophages engulfing apoptotic cells were rarely observed in the late stage of fibrous septa (FS) in the PS-treated SHR liver. In Experiment II with normotensive F344 rats, histopathological features of early FS in the liver were compared with those of late FS observed in Experiment I using serial sections, and we found that FS developed along the wall of newly formed vessels to connect between neighboring central veins. However, the effect of hypertension on this fibrosis could not be clearly demonstrated in the present study using SHRs and 2K1C rats.

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PubMed1997

Hepatoblastoma in a dog.

A hepatoblastoma was found in a 13-year-old female Maltese dog. Histologically, the tumor showed a wide trabecular pattern and was frequently accompanied with vascular lake formation. Tumor cells were positive for cytokeratin and neuron specific enolase, but negative for chromogranin. Electronmicroscopically, tumor cells were accompanied with continuous basement membrane and had poorly developed desmosomes. Sinusoidal endothelia had fenestration and were surrounded by myofibroblast-like cells. To the best of our knowledge, this paper is the first report of morphological studies on canine hepatoblastoma.

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PubMed1997

Morphological and immunohistochemical studies on porcine serum-induced rat liver fibrosis.

In order to clarify the pathogenesis of porcine serum (PS)-induced rat liver fibrosis, three experiments differing in dose of PS or duration of treatment were performed on male Fischer 344 rats. The rats were given an intraperitoneal injection of PS twice a week for 3 to 16 weeks and euthanized 7 days after the last injection for each treatment group. Liver tissues from these animals were subjected to detailed morphological and immunohistochemical examinations. Biochemical tests on treated rat serum revealed an increase in globulin concentration but no elevation in AST, ALT and ALP activities. There were no relationships among the dose of PS, the extent of fibrosis, and the anti-PS antibody titer. A number of alpha-smooth muscle actin-positive non-myofibroblastic cells, desmin-positive cells, and lipofuscin-laden Kupffer cells were found around the central veins and in the fibrous septa. In advanced stages of fibrosis, a proliferation of elastic fibers were observed in the septa. These findings were considered to indicate gradually occurred hepatocellular necrosis. The vascular endothelial cells in the fibrous septa expressed factor VIII-related antigen, exhibited fenestration accompanied by basement membrane formation, and were surrounded by Ito cells. Most of the portal vein branches showed hypertrophic thickening of the smooth muscle layer, resulting in narrowing of the lumen. These vascular changes suggested that hemodynamic alterations of the intrahepatic circulation induced hepatocellular necrosis/apoptosis and played an important role in the pathogenesis of porcine serum-induced liver fibrosis in rats.

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PubMed1996

Stimulative effect of epinephrine on glucose production and utilization rates in sheep using a stable isotope.

The rates of the production and utilization of blood glucose were measured during intravenous epinephrine infusion (2.0 nmol kg-1 min-1 for 1 hr) in sheep. An isotope dilution method with an infusion of [U-13C]glucose and nonsteady-state equations were used for the determination of blood glucose kinetics. Heart rate and concentrations of blood glucose, plasma free fatty acids, and lactate increased (P < 0.01), whereas plasma insulin concentrations tended to decrease (P < 0.06) during epinephrine infusion. The blood glucose turnover rate was 1.9 +/- 0.1 mg kg-1 min-1 before epinephrine infusion. The rate of blood glucose production increased (P < 0.01) to 6.4 +/- 0.5 mg kg-1 min-1 at 20 min after the initiation of epinephrine infusion. The blood glucose utilization rate increased (P < 0.05) gradually and reached 4.1 +/- 1.2 mg kg-1 min-1 at 60 min after the initiation of epinephrine infusion. These results suggest that in sheep, epinephrine stimulates the rates of both the production and the utilization of blood glucose and that hyperglycemia induced by epinephrine infusion is mainly due to a rapid enhancement in the rate of the production of blood glucose.

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PubMed1996

Morphological study on a case of canine hepatic nodular fibrosis.

Hepatic nodular fibrosis occurred in an 8-year-old male Papillon dog. Fibrous nodules, consisting of broad bands of collagen fibers, spindle cells, and lipofuscin-laden foamy macrophages, were well-circumscribed and frequently linked up with the portal areas. Because the spindle cells were positive for desmin and/or alpha-smooth muscle actin, they might be Ito cells or myofibroblasts. These results suggest that both the spindle cells and macrophages play an important role in the pathogenesis of hepatic nodular fibrosis, which might arise from the portal area.

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PubMed1996

Immunohistochemical and ultrastructural studies on the sinusoidal lining cells of canine hepatocellular carcinoma.

Immunohistochemical and ultrastructural studies were performed on the sinusoidal lining cells of eight canine hepatocellular carcinomas. The sinusoidal endothelial cells of the tumors had a positive reaction for both Factor VIII-related antigen and peanut agglutinin, but did not bind with Ulex europaeus agglutinin-1. Desmin- and lysozyme-positive cells were present along the sinusoids and perisnusoidal spaces of the tumor tissues, respectively, but were fewer in number compared with those of normal canine liver. Alpha-Smooth muscle actin-positive cells outlining the sinusoids were frequently observed. Electron microscopy revealed that basement membranes were often formed beneath the sinusoidal endothelial cells, with rare fenestration. Macrophages were present around or within the sinusoids and tended to increase in number relative to the degree of tumor differentiation. Myofibroblast-like cells with various morphological features, consistent with alpha-smooth muscle actin-positive cells, were frequently found in the perisinusoidal space. The present study indicates that the sinusoidal lining cells of canine hepatocellular carcinoma have some phenotypic characteristics.

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PubMed1994

Lymphangiosarcoma in a dog.

Lymphangiosarcoma was seen in the subcutis of right chest in a 11-year-old female Poodle. No metastasis was observed clinically. Tumor cells were vimentin positive and formed irregular space or slit without erythrocytes in the tumor tissue. Lymphocytic foci and edema were seen in the stroma. Only a few tumor cells had factor VIII-related antigen. Electronmicroscopically, tumor cells did not accompany with basement membrane and intercellular junctional complex.

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PubMed1993

Historical control data of organ weight and gross findings in F344/DuCrj rats and B6C3F1 mice.

Organ weight and gross postmortem findings of control Fischer 344/DuCrj rats and B6C3F1 mice are presented from subchronic, chronic toxicity and carcinogenicity studies that were conducted over a 9 year period at our center (An-Pyo Center). The mean organ weight of the liver, kidney, spleen and the lung were increased associated with age in both species. The most common findings observed at 109 weeks in both species were thymic atrophy, enlargement of the spleen, dilation of the lumen of the uterus and ovarian cysts. Male and female Fischer 344/DuCrj rats commonly exhibited a granular surface of the kidneys, hypertrophy of and/or nodular pituitary glands and subcutaneous tissue masses. Multiple white patches and hypertrophy or atrophy of the testes, atrophy of the seminal vesicles and prostate and nodules in the pancreas were seen frequently in male rats. Malformative nodule in the liver was a common finding in female rats. The most common lesions seen in both male and female B6C3F1 mice were nodules in the liver and lungs and enlargement of the lymph nodes. Nodules on the preputial gland were commonly seen in the males. Sex differences were evident in the incidence of some of the above findings. These historical data will contribute to analyze the organ weight and gross findings at necropsy in long-term toxicity and carcinogenicity studies.

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PubMed1990

The bone-titanium interface in vitro.

Commercially pure 5-mm-diameter titanium (cpTi) discs received droplet inoculations of cells derived from rat bone marrow and were maintained in supplemented culture medium for 2-3 weeks. The cells and extracellular matrix (ECM) were processed for observation by light (LM), scanning (SEM), and transmission electron (TEM) microscopy. The latter was achieved by freeze-fracturing the solid metal from the resin-embedded tissue using a method which preserved the interface. Surface staining of whole discs revealed cells separated from the metal substratum by areas of ECM which stained positively using von Kossa's method to identify mineralization. At SEM, the ECM comprised dense interwoven collagen fiber networks which were partially obscured by globular masses (GMs). Individual GMs were associated with collagen fibers, especially at fiber intersections. EDAX line scan analysis confirmed the presence of Ca and P in these areas which were assumed to be spheritic foci of calcification since the Ca and P peaks diminished in areas which demonstrated only collagen fibers or the underlying cpTi. TEM examination confirmed the presence of globular mineralization and also revealed the presence of an interfacial zone between the metal substratum and the mineralized ECM elaborated by osteoblasts during the culture period. The interfacial zone comprised two layers, a bonding zone containing few collagen fragments and a ruthenium red positive layer containing more densely packed collagen fibers. We believe that this is the first report of both the formation of bonelike tissue on solid titanium substrata in vitro and demonstration of an interface which bears close morphological similarities to that known to develop in vivo.

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PubMed1988

Reconstituted bovine skin collagen enhances healing of bone wounds in the rat calvaria.

The value of reconstituted fibrillar collagen (Zyderm Collagen Implant I, a concentrated solution of pepsin-solubilized, bovin skin collagen) as a bone graft material was tested in 4 mm diameter surgically created defects of rat calvaria. All wounds were allowed to heal for 4 weeks, and were assessed both qualitatively and by computer-assisted morphometry. The fibrillar collagen was found to produce significantly more new bone than no graft or than heat-denatured fibrillar collagen. The fibrillar collagen was generally well tolerated, appeared to act as a hospitable osteoconductor, and became incorporated into the newly formed bone. The effect of collagen concentration was also tested by comparing the fibrillar collagen at 3.5% (Zyderm Collagen Implant I) with 6.5% suspension of collagen (Zyderm Collagen Implant II). There were no significant differences observed, but a definite trend was evident for Zyderm II to encourage more bone formation than Zyderm I. It is concluded that reconstituted fibrillar collagen is a hospitable, osteoconductive substance that enhances bone healing of calvarial defects in the rat.

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