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Pneumocystis carinii is an opportunistic unicellular organism that can cause serious pulmonary infection in immunosuppressed patients. The taxonomy and classification of P. carinii has not yet been settled. The authors present transmission and scanning electron microscopic (TEM and SEM) observations of tissue from two patients with pulmonary Pneumocystis infections. The infectious organisms display marked variability in shape and size. They appear to divide by binary fission and lack motility organelles, Golgi apparatus, phagosomes, and lysosomes. The mitochondria and endoplasmic reticulum were poorly developed. The nucleus was rather ill defined, and there appeared to be asynchrony in the development of nuclear membranes and cytoplasm. The authors contend that there are firm ultrastructural evidences against the claim for a protozoan nature of Pneumocystis and in favor of its being a fungus, albeit of a primitive form, in which the mycelium is reduced to a unicellular state but the ability to sporulate is preserved.
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PMID:Pneumocystis carinii. Taxonomy as viewed by electron microscopy. 349 82

The purpose of this investigation is to examine the process of atrial septation in the embryonic rat heart utilizing scanning (SEM) and transmission (TEM) electron microscopy. SEM shows septum primum, the first partition to develop, to extend from the dorsocranial wall of the primitive atrium by day 12.50. This begins the division of the common chamber into right and left portions. As septum primum grows foramen primum decreases in size and a second interatrial communication develops. Foramen secundum rapidly develops in the ventrocranial portion of septum primum during days 13.00 through 15.50. TEM studies of septum primum in the area of foramen secundum formation demonstrate that foramen formation is accomplished through transseptal communications established by cellular processes of rounded-up endocardial cells. These extensions protrude into the septal core isolating the septal tissue into small cords and the size of foramen secundum is increased. Areas of extremely dilated rough endoplasmic reticulum are prominent in the rounded-up endocardial cells and have a characteristic honeycomb appearance. No evidence of cell death is seen. A second septum develops to the right of septum primum and scanning electron micrographs show it to be a definitive partition by 16.50 days. At the fine structural level, elongated endocardial cells cover a center of myocytes containing many myofibrils, ribosomes and mitochondria.
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PMID:Atrial septation in the rat. II. An electron microscopic study. 371 12

The effect of bromocriptine (BEC) treatment on spontaneous, sparsely granulated, prolactin-producing pituitary adenomas was studied in aging female Long-Evans rats of at least 23 months of age. Rats treated with BEC for 1-44 days showed a marked decrease in serum prolactin (PRL) concentrations at the end of the treatment period (9.1-34 ng/ml) when compared to the serum PRL levels of age-matched control animals (94.6-233 ng/ml). No significant differences in serum PRL levels (ng/ml; mean +/- SEM) were noted in rats withdrawn for 14 days from BEC treatment (132.9 +/- 18.8) when compared to age-matched controls (181.5 +/- 70.9). The mean pituitary weight (mg) was significantly reduced in the rats treated for 44 days with BEC (23.4 +/- 1.4) compared to untreated controls (43.4 +/- 8.3). At the time of sacrifice, PRL-producing adenomas were found in 16 of 33 control rats, 5 of 10 rats treated for 1 day with BEC, 5 of 20 rats treated with BEC for 44 days, and 12 of 28 rats in the animals withdrawn from BEC treatment for 14 days. Morphometric analysis of sparsely granulated PRL-containing adenomas revealed that, although the nuclear area was reduced after 1 day of BEC treatment, the cytoplasmic area was reduced only after 44 days. Forming granule diameters were significantly increased after 44 days of BEC treatment and markedly decreased in the withdrawal group. Storage granule diameters were increased in both the 1-day and 44-day groups and were decreased in rats withdrawn from BEC for 14 days. Rough endoplasmic reticulum, forming granule, storage granule, and lysosome volume densities were increased after 1 day of BEC treatment. The Golgi region volume density decreased only after 44 days of BEC treatment. We conclude that aging female Long-Evans rats harboring PRL-producing pituitary adenomas can respond to BEC administration with a decrease in serum PRL levels and morphologic changes in adenoma cells. However, the structural alterations in PRL cells of the rat adenomas are less conspicuous than those of human tumors. In the rat, like in human patients, a direct toxic effect of BEC on PRL-producing adenoma cells has not been demonstrated.
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PMID:Spontaneous sparsely-granulated prolactin-producing pituitary adenomas in aging rats. A prospective study of the effect of bromocriptine. 404 38

The metamorphosis of the epibranchial cartilage, a skeletal component of the hyobranchial apparatus, in the salamander Eurycea bislineata entails a combination of the reabsorption of a larval cartilaginous element with the simultaneous genesis of an adult cartilage in the same place. In this study we focus on the fate of the larval chondrocytes. Two hypotheses are considered: one, larval cells simply die off during metamorphosis, or, alternatively, they dedifferentiate and participate in the formation of the adult element. Thyroxine treatment and experimental tissue manipulation coupled with measurements of thyroxine levels using radioimmunoassay show that, within 24 h after T4 treatment, larval chondrocytes in the epibranchials exhibit large autophagocytic vacuoles, disruption of the rough endoplasmic reticulum, abnormally shaped mitochondria, abundance of lysosomes and nuclear degeneration, all symptoms of the onset of cell death. In conclusion, evidence from light microscopy, TEM and SEM show that the larval chondrocytes in response to rising levels of thyroid hormones undergo a process of lysosomal autophagocytosis and do not participate in the formation of adult structures.
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PMID:The fate of larval chondrocytes during the metamorphosis of the epibranchial in the salamander, Eurycea bislineata. 407 41

We used the technique of lineal analysis to study the influence of 48 h of hyperoxia on cytoplasmic organelles of pulmonary granular pneumocytes with particular reference to their lamellar bodies. We undertook this study because lamellar bodies are considered to be storage granules for pulmonary surfactant and because we had found that hyperoxia decreased [(14)C]leucine incorporation into protein of a surface-active lung fraction. We found that for lamellar bodies the percent cytoplasmic volume was 12.8+/-1.5 (mean+/-SEM) and 8.4+/-2.2, the organelle area (mum(2)) per organelle was 0.98+/-0.13 and 0.62+/-0.10 and the organelle volume (mum(2)) was 0.35+/-0.04 and 0.18+/-0.01, for air- and oxygen-exposed rats, respectively, (P=<0.05). The surface density of the lamellar body membrane was 7.05+/-0.47 and 9.36+/-0.96 (P=<0.05) for air- and oxygen-exposed rats. There were no differences in lamellar body number per cytoplasmic area or per pneumocyte between air- and oxygen-exposed rats. There were no statistical differences in these parameters between mitochondria of air- or oxygen-exposed rats. The surface density of the rough endoplasmic reticulum was the same in both groups. This study indicates that granular pneumocytes of rats exposed to hyperoxia have the same number of lamellar bodies as control rats but the lamellar bodies are smaller. This findings in consistent with the hypothesis that the hyperoxia-induced decrease in protein synthesis by lung represents at least in part a decreased synthesis of the secretory lipoprotein-pulmonary surfactant.
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PMID:Hyperoxia: a stereologic ultrastructural examination of its influence on cytoplasmic components of the pulmonary granular pneumocyte. 468 81

Isolated rat hepatocytes in early primary culture were incubated in the presence of three substituted nitroimidazoles currently of clinical interest as tumour radiosensitisers. The effects of 3h treatments with Misonidazole (MISO), Desmethylmisonidazole (DESMISO) and the basic compound Ro 03-8799 were monitored both directly from treatment and following a 24h 'recovery' period. Morphological changes were observed by SEM and TEM and included effects on the plasma membrane and the nucleus. The plasma membrane of DESMISO and 03-8799 treated cells was characterised by blebbed regions not present in control cultures, and considered indicative of an early toxic insult. Blebs were most evident in 03-8799 treated hepatocytes where they often contained coils of endoplasmic reticulum within the ground plasma. Blebbed areas were less evident 24h after the removal of the drugs from surviving cells. An increased aggregation of peripherally located heterochromatin within the nucleus was the other main morphological alteration induced by nitroimidazole treatment. This was again more prevalent in 03-8799 and DESMISO exposures; and particularly in cells demonstrating membrane damage. Parallel viability studies indicated an efficacy of the nitroimidazole towards rat liver parenchymal cells in primary culture of Ro 03-8799 greater than DESMISO greater than MISO. This fitted the order predicted from the morphological findings and from previously published clinical data. The validity of monitoring structural parameters as a means of initially indicating lesion sites following drug treatments in the hepatocyte cytotoxic screening model is considered.
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PMID:Morphological changes in rat hepatocytes in primary culture induced by Misonidazole, desmethylmisonidazole and Ro 03-8799. 614 29

Mammary adenocarcinomas from C3H/HeJ mice carrying the mammary tumor virus were studied by means of light, transmission, and scanning electron microscopy. The histological appearance of the tumors was variable; however, 60% were classified as type B adenocarcinomas, while 20% were type A and 20% were composed of equal regions characteristic of both types. Four populations of tumor cells were observed with the TEM. The most abundant of these, primitive glandular cells, were characterized by large, regular, euchromatic nuclei and cytoplasm containing numerous free ribosomes, little rough endoplasmic reticulum, few mitochondria, small Golgi complex and a variable number of type A virus particles. Specialized glandular cells contained highly pleomorphic nuclei, many lysosomes, lipid droplets, multivesicular bodies, profiles of rough endoplasmic reticulum and granules resembling secretory proteins. Myoepithelial cells and dark glandular cells with abundant organelles, large Golgi complexes, dense cytoplasmic matrix and very heterochromatic nuclei were observed infrequently. The SEM revealed tumor cells to be variable in size, shape and surface characteristics. Most cells were rough in texture, displaying irregular ridges, small blebs and a few short microvilli. The contours of some cells were smooth, and a few cells had short, irregular microvilli on limited regions of their surfaces. Cells lining ducts within the tumor had microvilli on their apical surface, but the number, size, shape and distribution of microvilli varied considerably. Cells lining ducts from non-tumor-bearing animals displayed less variation in size, shape and surface morphology.
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PMID:Fine structure analysis and surface characteristics of mouse mammary gland adenocarcinomas. 633 Aug 78

Fibrous capsules surrounding silicone implants were investigated in a new guinea pig model to delineate some of the factors leading to capsular contracture. Both the implant surfaces and tissue capsules were examined by light and scanning transmission electron microscopy (STEM + SEM) with x-ray energy spectroscopy (XES). The capsular tissues were qualitatively similar to those recovered clinically, showing dense parallel collagen deposits, fibroblasts, myofibroblasts, macrophages, and foreign-body giant cells. Silicone was positively identified within intercellular vacuoles and the rough endoplasmic reticulum of macrophages by XES. Tissue recovered from the capsules that surrounded implants that were contaminated with S. aureus presented a qualitatively similar histologic spectrum. The contaminated specimens did show an accelerated response. SEM showed a cellular invasion of the silicone envelopes. We conclude that the model accurately simulates the clinical situation and suggests that immune mechanisms may play a key role in capsular contracture.
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PMID:Acceleration of capsule formation around silicone implants by infection in a guinea pig model. 636 30

The antipsychotic drug trifluoperazine (TFP) causes a reversible rounding of cells of the rat liver epithelial cell line, WIRL. We have investigated the cytoplasmic organization of these cells after TFP treatment using SEM, TEM and immunofluorescence and have observed significant differences between the control and treated cells. Mitochondria are converted to the condensed configuration with distended cristae and the endoplasmic reticulum becomes tubular with distended cisternae. Intermediate filaments, visualized with a monoclonal antibody, are aggregated to a cap on the nucleus in an arrangement different from that induced by colcemid.
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PMID:Alterations of the cytoplasmic organization of WIRL cells induced by trifluoperazine. 636 51

Ultrastructural studies with the transmission (TEM) and scanning (SEM) electron microscopes have added greatly to our knowledge of cellular structure and function in the liver. The normal polyhedral hepatocyte has numerous subcellular organelles, such as mitochondria, peroxisomes, lysosomes and complex rough (rer) and smooth (ser) endoplasmic reticulum. The normal hepatocyte stores glycogen, and sometimes lipid droplets, and secretes bile through the bile canaliculi between adjacent liver cells. It receives nutrients from the sinusoidal lumen across a fenestrated endothelium which is separated by the Space of Disse' from the plasma membrane. The Space of Disse' contains a scant network of reticulin fibers but no basal lamina. Two types of parasinusoidal cells are found in Disse's space: the fat storing cells of Ito, and the Pit cells which may have an endocrine function. The diseased liver has yielded much information in studies with TEM and SEM. The studies with TEM have been most helpful in studying the etiology of infectious diseases such as hepatitis B; have revealed organelle changes such as megamitochondria in cirrhosis and the fibrillar nature of alcoholic hyaline; have led to the identification of specific deposits in metabolic and storage diseases such as hemochromatosis (iron). Wilson's disease (copper), and alpha-1-antitrypsin deficiency (glycoprotein) have proven useful in identifying drug induced liver cell changes such as proliferation of SER and cholestasis, and are useful for identifying specific cell types in inflammatory and neoplastic diseases. In the future, both TEM and SEM coupled with histochemical, cytochemical, immunohistochemical and other analytic techniques will continue to add greatly to our understanding of the liver in health and disease.
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PMID:Ultrastructure of the liver and biliary tract in health and disease. 637 90


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