Exposure to a sublethal concentration of methyl parathion (MEP) reduced the activity of cytoplasmic malate dehydrogenase. mitochondrial malate dehydrogenase, and lactate dehydrogenase by 30 to 49% in the liver and the...Exposure to a sublethal concentration of methyl parathion (MEP) reduced the activity of cytoplasmic malate dehydrogenase. mitochondrial malate dehydrogenase, and lactate dehydrogenase by 30 to 49% in the liver and the skeletal muscle of the freshwater catfish, Clarias batraclms, after 7 days. The activities then began to recover and reached the control levels on the 28th day of MEP exposure. A complete recovery occurred on the 7th day when MEP was withdrawn from the medium after an exposure for 1 week. The withdrawal-dependent recovery in the activities was inhibited partially or completely by actinomycin Dandcycloheximide, suggesting de nova synthesis of the enzymes during the recovery period. A conjoint treatment of MEP and triiodolhyronine (T_3) restored the activities to control levels, indicating T_3 protection against the pesticide toxicity. SDS-PAGE of the cytoplasmic fraction of the liver showed some noticeable changes in the protein pattern after an exposure to MEP. Ultrastructural studies on MEP-treated liver cells showed disappearance of the glycogen granules and appearance of numerous smooth endoplasmic reticulum, lysosomal dense bodies, and swollen mitochondria. These changes in the liver are an indication of hepatic toxicity leading toward necrosis.(c) 1990 Academic Press.Inc.展开更多
To observe the process of invasion, retina of rat was used as a model to substitute the inner limiting membrane of retina for the basement membrane. Retina invaded by esophageal carcinoma cells and B16 melanoma cells ...To observe the process of invasion, retina of rat was used as a model to substitute the inner limiting membrane of retina for the basement membrane. Retina invaded by esophageal carcinoma cells and B16 melanoma cells upon the inner limiting membrane was studied by scanning and transmission electron microscopy. The results showed that the inner limiting membrane was destroyed by both kinds of tumor cells. The process of destruction was followed by a series of transformations in the inner limiting membrane, i.e. folding, swelling, thickening, and granular change. The inner limiting membrane was dissolved focally as a result of transformation, and then tumor cells invaded the retina through these dissolved regions. It seems that, as a barrier, the inner limiting membrane plays a similar role as the basement membrane.展开更多
AIM:To investigate the ultrastructure of oval cells in children with chronic hepatitis B,with special emphasis on their location in areas of collagen fibroplasia. METHODS:Morphological investigations were conducted on...AIM:To investigate the ultrastructure of oval cells in children with chronic hepatitis B,with special emphasis on their location in areas of collagen fibroplasia. METHODS:Morphological investigations were conducted on biopsy material obtained from 40 children,aged 3-16 years with chronic hepatitis B. The stage of fibrosis was assessed histologically using the arbitrary semiquantitative numerical scoring system proposed by Ishak et al. The material for ultrastructural investigation was fixed in glutaraldehyde and paraformaldehyde and processed for transmission-electron microscopic analysis. RESULTS:Ultrastructural examination of biopsy specimens obtained from children with chronic hepatitis B showed the presence of two types of oval cells,the hepatic progenitor cells and intermediate hepatic-like cells. These cells were present in the parenchyma and were seen most commonly in areas of intense periportal fibrosis (at least stage 2 according to Ishak et al) and in the vicinity of the limiting plate of the lobule. The activated nonparenchymal hepatic cells,i.e. transformed hepatic stellate cells and Kupffer cells were seen in close proximity to the intermediate hepatic-like cells. CONCLUSION:We found a distinct relationship between the prevalence of oval cells (hepatic progenitor cells and intermediate hepatocyte-like cells) and fibrosis stage in pediatric patients with chronic hepatitis B.展开更多
A method is described which permits transmission electron microscope of single cells treated with HpD plus laser microirradiation. The preselected single cell that was irradiated by laser under light microscope and fo...A method is described which permits transmission electron microscope of single cells treated with HpD plus laser microirradiation. The preselected single cell that was irradiated by laser under light microscope and followed fixation, embedded and sectioning is examined under electron microscope. The results demonstrated that at the light dose of 1.88 ml/μm2 not only the irradiated nucleolus appeared transparent region, but the other parts such as non-irradiated mitochondria in cytoplasm can also be damaged. When partial cytoplasm is irradiated with the light dose of 4.50 ml/μm2, the damages appear in all cytoplasm, but there is little change in the nucleus. The experimental results also demonstrate that cytoplasm is more sensitive than nucleus. It is the mitochondria in cytoplasm that are very sensitive to HpD plus laser.展开更多
文摘Exposure to a sublethal concentration of methyl parathion (MEP) reduced the activity of cytoplasmic malate dehydrogenase. mitochondrial malate dehydrogenase, and lactate dehydrogenase by 30 to 49% in the liver and the skeletal muscle of the freshwater catfish, Clarias batraclms, after 7 days. The activities then began to recover and reached the control levels on the 28th day of MEP exposure. A complete recovery occurred on the 7th day when MEP was withdrawn from the medium after an exposure for 1 week. The withdrawal-dependent recovery in the activities was inhibited partially or completely by actinomycin Dandcycloheximide, suggesting de nova synthesis of the enzymes during the recovery period. A conjoint treatment of MEP and triiodolhyronine (T_3) restored the activities to control levels, indicating T_3 protection against the pesticide toxicity. SDS-PAGE of the cytoplasmic fraction of the liver showed some noticeable changes in the protein pattern after an exposure to MEP. Ultrastructural studies on MEP-treated liver cells showed disappearance of the glycogen granules and appearance of numerous smooth endoplasmic reticulum, lysosomal dense bodies, and swollen mitochondria. These changes in the liver are an indication of hepatic toxicity leading toward necrosis.(c) 1990 Academic Press.Inc.
文摘To observe the process of invasion, retina of rat was used as a model to substitute the inner limiting membrane of retina for the basement membrane. Retina invaded by esophageal carcinoma cells and B16 melanoma cells upon the inner limiting membrane was studied by scanning and transmission electron microscopy. The results showed that the inner limiting membrane was destroyed by both kinds of tumor cells. The process of destruction was followed by a series of transformations in the inner limiting membrane, i.e. folding, swelling, thickening, and granular change. The inner limiting membrane was dissolved focally as a result of transformation, and then tumor cells invaded the retina through these dissolved regions. It seems that, as a barrier, the inner limiting membrane plays a similar role as the basement membrane.
文摘AIM:To investigate the ultrastructure of oval cells in children with chronic hepatitis B,with special emphasis on their location in areas of collagen fibroplasia. METHODS:Morphological investigations were conducted on biopsy material obtained from 40 children,aged 3-16 years with chronic hepatitis B. The stage of fibrosis was assessed histologically using the arbitrary semiquantitative numerical scoring system proposed by Ishak et al. The material for ultrastructural investigation was fixed in glutaraldehyde and paraformaldehyde and processed for transmission-electron microscopic analysis. RESULTS:Ultrastructural examination of biopsy specimens obtained from children with chronic hepatitis B showed the presence of two types of oval cells,the hepatic progenitor cells and intermediate hepatic-like cells. These cells were present in the parenchyma and were seen most commonly in areas of intense periportal fibrosis (at least stage 2 according to Ishak et al) and in the vicinity of the limiting plate of the lobule. The activated nonparenchymal hepatic cells,i.e. transformed hepatic stellate cells and Kupffer cells were seen in close proximity to the intermediate hepatic-like cells. CONCLUSION:We found a distinct relationship between the prevalence of oval cells (hepatic progenitor cells and intermediate hepatocyte-like cells) and fibrosis stage in pediatric patients with chronic hepatitis B.
文摘A method is described which permits transmission electron microscope of single cells treated with HpD plus laser microirradiation. The preselected single cell that was irradiated by laser under light microscope and followed fixation, embedded and sectioning is examined under electron microscope. The results demonstrated that at the light dose of 1.88 ml/μm2 not only the irradiated nucleolus appeared transparent region, but the other parts such as non-irradiated mitochondria in cytoplasm can also be damaged. When partial cytoplasm is irradiated with the light dose of 4.50 ml/μm2, the damages appear in all cytoplasm, but there is little change in the nucleus. The experimental results also demonstrate that cytoplasm is more sensitive than nucleus. It is the mitochondria in cytoplasm that are very sensitive to HpD plus laser.
