Ion irradiation is a very promising tool to modify the chemical structure and physical properities of polymers. This study was aimed to evaluate the cellular adhesion to ion beam-irradiated surface of biodegradable poly-llactide(PLLA) membrane. The PLLA membrane samples were irradiated by using 35 KeV Ar+ to fluence of 5x10(13), 5x10(14) and 5x10(15)ion/cm2. Water contact angles to control and each dose of ion beam-irradiated PLLA membranes were measured. Cultured fetal rat calvarial osteoblasts were seeded onto control and each dose of ion beam-irradiated PLLA membranes and cultured. After 24 hours, each PLLA membranes onto which osteoblasts attached were examined by scanning electron microscopy(SEM). Osteoblasts were removed from each PLLA membrane and then, the vitality and the number of cells were calibrated. Alkaline phosphatase of detached cells from each PLLA membranes were measured. Ion beam-irradiated PLLA membranes showed no significantly morphological change from control PLLA membranes. In the measurement of water contact angle to each membrane, the dose range of ion beam employed in this study reduced significantly contact angles. Among them, 5x10(14) ion/cm2 showed the least contact angle. The vitalities of osteoblastes detached from each membranes were confirmed by flow cytometer and well attached cells with their own morphology onto each membranes were observed by SEM. A very strong improvement of the cell adhesion and proliferation was observed for ion beam-irradiated surfaces of PLLA membranes. 5x10(14)ions/cm2 exhibited the most strong effect also in cellular adherence. ALPase activities also tended to increase in ion beam-irradiated membranes but statistical differences were not found. These results suggested that ion beam irradiation is an effective tool to improve the adhesion and spreading behaviour of the cells onto the biodegradable PLLA membranes for the promotion of membrane-tissue integration.
Rats ; Animals

To investigate the microvascular changes in primary pulmonary hypertension, the lungs of 24 Sprague-Dawley rats were treated by an intraperitoneal injection of 2% monocrotaline(MCT) solution and then examined with scanning electron microscopy(SEM) after microvascular corrosion casting. Histologic examination revealed significant medial thickening in the small to medium-sized pulmonary arteries. Scanning electron microscopic findings of the normal lungs showed two kinds of microvascular structures. One showed a well-fortned three-dimensional basket structure of uniform flat-tubular alveolar capillaries, which were connected to each other in a T or Y shape or at right angles. The other revealed a two-dimensional reticular sheet of round tubular branches mainly in the bronchial artery-supplying regions. The MCT-treated groups(remodelling) showed apparent changes in both kinds of microvasculatures in comparison to the normal group but the more prominent change was found in Lbe bronchial artery microvasculature showing the dense thick encasement around large pulmonary arteries. Alveolar microvasculature of the pulmonary artery revealed individually enlarged angular appearance, with generally deformed alveolar architecture. Quantitatively, the significant enlargement of diameter and intercapillary distance appeared in both microvasculatures of MCT-induced rat lungs, but the density was increased only in the bronchial artery microvasculature. In conclusion, our three-dimensional microvascular study of the MCT-treated rat lungs demonstrates a new morphologic finding of vascular remodeling in primary puhnonary hypertension, which is thought to play an important vascular role in the pathogenesis in addition to interstitial fibrosis.
Rats ; Animals

To investigate the tubular major histocompatibility complex(MHC) expression and inflammatory phenotypes in tubulointerstitial nephritis, Lewis rats were inununized with azobenzen-earsonate-tyrosine in complete Freund adjuvant and challenged either foot pad or kidney, either by subcapsular injection or by ex vivo perfusion. The rats were sacrificed 2, 3, 5, 10 and 15 days after antigenic challenge. Foot pad swelling was significant at the antigenic challenge site (151.8 vs 6.8 x 10(-2) mm) at 24 hours. Tubulointerstitial nephritis was induced by both methods and the inflammatory infiltrate which first appeared on day 2, became prominent at day 5, then gradually subsided in ex vivo perfused rats, while inflannnation started on day 3 in subcapsular injected rats. The major site of inflammation was in the cortex and outer stripe of the outer medulla, with predominance of mononuclear cells throughout the course. The inflammatory cells showed mainly OX8 and ED1 positivity with OX19, W3/25 and CD5 positivity in minority. RT1B expression was diffuse in the cytoplasm of proximal tubules at day 2 and 5. These results suggest the involvement of cell mediated immunity in this experimental model, and the possibility that tubular epidielial cells process antigen and then become targets in immune injury.
Rats ; Animals

Although there have been many reports about the importance of the spleen's role in hepatic fibrogenesis, the exact mechanism is still uncertain. The author designed this study to evaluate splenic function on hepatic fibrogenesis. The degree of hepatic fibrosis and the population of splenocyte subsets were studied in the experimental animal model with fibrosis produced by injecting normal swine serum intra-peritoneally into Sprague-Dawley rats. The animals were divided into three groups; group A was subjected to injection of swine serum only, group B swine serum and complete Freund's adjuvant and group C swine serum and cyclosporin A. The experimental hepatic fibrogenesis by swine serum was augumented by coinjection with the adjuvant and inhibited by cyclosporin A. The study of the splenocyte subset revealed increased percentages of spienic B cell and CD4+ cell and a decreased percentage of CD8+ cell, and these changes of splenocyte subset were also augumented by the adjuvant and inhibited by cyclosporin A. The percent of monocytes was not significantly altered, although a tendancy of early decrease by the adjuvant was noted.
Rats ; Animals

Since the role of excitatory amino acids such as glutamate and aspartate and their receptors mediating cellular injury through various mechanisms were known in hypoxic-ischemic injury and associated diseases of central nervous system, blocking agents for transmitter release or receptors have been tried to reduce the cellular damages and subsequent sequelae experimentally. Several in vitro studies suggested two kinds of glutamate neurotoxicity: (1) rapid toxicity due to influx of sodium or chloride with resultant cellular edema and consequent damage, which is associated with N-methyl-D-Aspartate(NMDA) as well as non-NMDA receptors, (2) calcium mediated delayed toxicity associated mainly with NMDA receptor. This study was conducted to investigate the role of rapid toxicity in hypoxic-ischemic injury. Early lesions of 30 minutes to 24 hours after hypoxic-ischemic insult were examined by autoradiography with radiolabelled glutamate and kainitic acid (KA) as well as light and electron microscopy. Late changes were evaluated on formaldehyde-acetic acid-methanol(FAM) fixed brain 1 week after the insult. Cornus ammonis(CA) l of hippocampus showed the highest density of NMDA receptors, which was decreased constantly from 2 hours to 24 hours. In contrast, CA3 of hippocampus showed the highest density of KA receptors, which was the lowest at 6 hour and increased thereafter. Light microscopic examination showed the worst changes during 30 minutes to 6 hours. After 1 week, most of the cases showed degeneration of neurons and CAI and CA3 did not show the difference. Electron microscopic examination showed marked degenerative changes of neurons as well as neuropils starting from 30 minutes after the insult. In conclusion, rapid toxicity mediated by non-NMDA(KA) receptor seen in CA3 lead to permanent damage in 1 week old lesion.
Rats ; Animals

To fine out the changes of DNA ploidy and cellular proliferation activity during carcinogenesis and evaluate correlation between flow cytometrically determined S-phase fraction and proportion of proliferation cell nuclear antigen(PCNA, PC10) immunoreactive cells, the authors studied on malignant fibrous histocytoma induced by intra-articular injection of 9, 10-dimethy1-1, 2-benzanthracene(DMBA) in the rats. Forty Wistar rats were used. The results obtained were as follows. 1) Firstly, tumors were palpated 5 weeks after the last injection of DMBA and formed in 27 rats at sacrificed. Histologically, these lesions showed storiform, indicative of malignant fibrous histiocytoma. 2) Three cases of DNA aneuploidy were observed at 4 and 5 months after the last injection of DBMA and one of them, which was DNA diploidy at main mass, was found at daughter mass. 3) Flow cytometrically determined S-phase fraction and proportion of PCNA(PC10) immunoreactive cells in malignant fibrous histiocytoma induced by DMBA were much higher than in control groups and slightly increased according to sequential changes after formation of mass. The comparison of flow cytometrically determined S-phase fraction and proportion of PCNA(PC10) immunoreactive cells showed significant correlation(r=0.6092, p<0.001). Above results strongly suggest that ploidy pattern may evolve into aneuploid type during the development of tumor and proliferation activity increases during the carcinogenesis.
Rats ; Animals

Amiodarone, an antiarrhythmic drug, may exert pulmonary toxicity in some patients but the pathogenesis is not clear. This study was carried out to investigate the pathogenetic mechanism of pulmonary injury induced by amiodarone at dose of 100 mg/kg/day given to rats by intraperitoneal injection for 3 weeks. And the preventive effects of concomitantly injected steroid (10 mg/kg/day) on amiodarone induced pulmonary injury was also studied using bronchoalveolar lavage, light microscopy and transmission electron microscopy. The results obtained were summarized as follows: Mild lymphocytosis of bronchoalveolar lavage fluid was found in all experimental groups. Intracytoplasmic lamellar body formation was found in all types of pulmonary cells and type II pneumocytes revealed the earliest abnormal lamellar body formation. The capillary endothelial cells showed cellular swelling and detachment from underlying basement membrane at early phase of experiment and the edema of alveolar wall and interstitium were noted. Interstitial fibrosis and proliferation of type II pneumocytes were noted at late phase. The lungs of steroid injected groups revealed accumulation of lamellar bodies in all types of pulmonary cells but interstitial fibrosis was not occurred. These findings support the concept that amiodarone is responsible for a drug-induced phospholipidosis and directly toxic to pulmonary endothelial and epithelial cells. And steroid may regress the progression of amiodarone induced pulmonary injury.
Rats ; Animals

The purpose of this study was to investigate the inhibitory role of vitamin A with respect to activation of Ito cells in fibrosis of the rat liver induced by common bile duct ligation(CBDL). The liver was examined by immunohistochemical staining for a-smooth muscle actin,the known marker of activated Ito cells, and light and electron microscopy after CBDL andCBDL with intraperitoneal injection of retinoic acid (Sigma, USA) 1 mg/Kg in 3 times per week. The results were sumrrlerized as follows: After CBDL, the bile ductules were markedly proliferated in the periportal areas extending toterminal hepatic veins. Interstitial fibrosis and inflammatory cell infiltration appeared, however,cholestasis was minimal. Retinoic acid treatment with CBDL decreased bile ductular proliferationand interstitial fibrosis compared to CBDL only. After CBDL, proliferated and activated Ito ceIs showing positive reaction in smooth muscle actin were present in the periductular andperisinusoidal areas, and areas of increased interstitial fibrosis. Activated ito cells weredecreased in number after CBDL with vitamin A treatment. Electron microscopically,intracytoplasmic fat droplets and the cytoplasmic processes of Ito cells were decreased afterCBDL. Myofibroblasts were frequently appeared in the interstitial fibrosis after CBDL. But,intracytoplasmic fat droplets of Ito cells were well preserved, and myofibroblasts were found lessfrequently after CBDL with vitamin A treatment. The results suggest that vitamin A plays an inbitory role in the activation and fibrogenesis ofIto cells after CBDL.
Rats ; Animals

Ultrastructural study of the effects of amiodarone on the liver tissue was performed. Rats were fed with amiodarone containing diet and were sacrificerd at 1st, 3rd, 4th, 5th and 8th weeks of experiment. Charateristic lisosomal inclusion bodies were appeared form first week, which were more prominent and increased in size at the 5th and 8th week of experiment. These inclusion bodies were found in hepatocytes, Kupffer cells, bile duct epithelial cells and fibroblasts but most prominent in hepatocytes. The lysosomal inclusion bodies could be divided into four types; those characterized by (1) dense bodies with packed crystaloid contents, (2) multilamellated bodies, (3) irregular shaped bodies with varying electron density and 4. dense bodies containing stacks of fine membranous structures. All types were found in all experimental groups. But the type 1 and 2 were predominent at early stage, while type 3 and 4 were more prominent at later stage According to these findings, the formation of the lysosmal inclusion body was a characteristic change in derangement of phospholipid metabolism. And amiodarone could induce disturbance of phospholipid metabolism in all kinds of cells in liver tissue.
Rats ; Animals

No abstract available.
Animals ; Rats*