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Query: UMLS:C1275122 (TEM)
 21,810 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Fine structural alterations of liver sinusoids in young and adult albino rats breathing 6% oxygen in nitrogen at normal atmospheric pressure for periods from 3 to 30 h were described by use of TEM and SEM. After short-term hypoxia the fenestrated areas of endothelial cells were partially destroyed. After long--term hypoxia wide gaps could be visualized in the endothelium, too. In the liver specimens of all hypoxic animals electron lucent membrane bounded blebs arose from the endothelial lining. Cytoplasmic protrusions of hepatocytes bulged into the sinusoidal lumen. In the space of Disse and the sinusoidal lumen bleblike corpuscles and parts of cytoplasmic membrane being discharged from liver cell vacuoles could be observed. The find structure of liver sinusoids in hypoxia was very similar in young and adult albino rats. The findings suggest a discharge of metabolites and cellular components from endothelial cells and hepatocytes in a state of energetic insufficiency by forming cellular blebs and protrusions. It was supposed, that the combined effects of hypoxia and shearing of circulating blood were responsible for the development of holes and gaps in the endothelial lining.
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PMID:[On the influence of hypoxia on the sinus endothelial cells of rat liver. A scanning and transmission electron microscopic investigation (author's transl)]. 82 Dec 46

OCP 9-176 is an oxycephem antibiotic that contains a 2-aminothiazolyl, carboxypropyl side chain at C-7 and a pyridinium thiomethyl group at C-3. OCP 9-176 was generally twofold less active than its sulfur-containing analog ME 1228 against Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, Providencia stuartii, Proteus vulgaris, and Serratia marcescens. Activity against Enterobacter cloacae and Citrobacter freundii was equivalent. OCP 9-176 was twofold less active than ME-1228 against Pseudomonas aeruginosa and Acinetobacter species. Activity of the two agents was similar against Staphylococcus aureus and Staphylococcus epidermidis. Although OCP 9-176 inhibited E. coli containing TEM-1 and TEM-2, it was less active than ME-1228. Klebsiella organisms with SHV-1 and K-2 beta-lactamases were inhibited, but TEM-3-containing isolates had MICs of 16 micrograms/ml. OCP 9-176 was minimally hydrolyzed by TEM-1, PSE-1, K-1, and P99, and it was a poor inhibitor of P99. Replacement of sulfur with oxygen does not increase the activity of compounds with sulfopyridinium methyl groups at C-3.
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PMID:In vitro activity of an oxycephem OCP 9-176 compared with its sulfur analog and other beta-lactams. 187 72

By the production of microbicidal agents, such as reactive oxygen species, activated PMN are capable of inducing tissue damage in the host. TNF-alpha was recently shown to be a potent activator of PMN oxidative metabolism. To further evaluate the interaction between activated PMN with physiological target cells, the effect of human PMN on cultured bovine aortic and human umbilical vein endothelial cells (EC) upon stimulation with human TNF-alpha was investigated by ultrastructural techniques: Scanning and transmission electron microscopy (SEM and TEM resp.) and ultrastructural detection of H2O2 production. When isolated PMN were added to EC in the presence of recombinant human TNF-alpha (10(3) U/ml) the EC-monolayer was disrupted within 4 h and EC changed their shape by exhibiting a spindle-like structure. PMN were seen in the intercellular spaces. Release of H2O2 was observed at the surface of the PMN plasma membrane, the luminal part of the small intracytoplasmic vacuoles in the PMN as well as in the contact zone between PMN and EC, but not within the EC. Scavengers of reactive oxygen species, such as superoxide dismutase and catalase or D-mannitol failed to block the effect of TNF-alpha-stimulated PMN on EC. In contrast, addition of NaN3 (0.1 mM), an inhibitor of myeloperoxidase activity, almost completely inhibited the disruption of EC-monolayers. Subsequent addition of NaN3-insensitive horseradish peroxidase reconstituted the effect. The results obtained suggest that TNF-alpha-stimulated PMN effectively cause the disruption of EC monolayers by an adherence-dependent mechanism which is mediated by the release of myeloperoxidase. The results may be of major importance for the pathogenesis of inflammatory vascular reactions.
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PMID:Interaction of granulocytes and endothelial cells upon stimulation with tumor necrosis factor-alpha: an ultrastructural study. 209 2

In the present study the functional and morphologic effects of two pulmoplegic solutions are evaluated. Single left-lung allotransplantation with ligation of the right pulmonary artery was performed in 15 piglets (13-20 kg). The lungs were preserved after donor prostaglandin E-1 treatment with single pulmonary artery flush with either modified Euro-Collins solution (mECS) (9 pigs) or oxygenated fluorocarbon emulsion (FC-43) (6 pigs) and transplanted after 6-hr storage in cold Physiosol solution. Tidal volumes of 15 ml/kg x fr (18) with 40% inspired oxygen were used for ventilation during reperfusion. Function of the transplanted lung was monitored for 4 hr postoperatively by determining pa CO2 and pa O2 levels from arterial samples and by noninvasive monitoring of end-tidal CO2 values and arterial oxygen saturations. Sequential morphologic changes in pulmonary artery flow surface and lung tissue were studied after 6-hr storage and 4-hr reperfusion, using light, scanning, and transmission electron microscopy (LM, SEM, TEM). There was no mortality. After transplantation the mECS group experienced significant hypoxia and hypercarbia and had low end-tidal CO2 values as signs of defective oxygenation and gas exchange, whereas the FC-43 group was normoxic and normoventilated without disturbed elimination of carbon dioxide. After storage and reperfusion, LM showed signs of increased vascular permeability and reperfusion damage--more evident in the mECS group compared with the FC-43 group--while the lymphoid cell population was more intensely activated in the latter group. Electron microscopy after storage showed good overall preservation of structures in both groups. After reperfusion preservation of pulmonary artery flow surface and lung tissue was estimated to be moderate in the mECS group, whereas it was good-to-moderate in the FC-43 group by SEM (NS). TEM of lung tissue, however, showed significantly better-preserved alveolar epithelial lining in the FC-43 group compared with the mECS group. In conclusion, oxygenated fluorocarbon (FC-43) pulmoplegia gave better functional and morphologic preservation of lung grafts compared with modified Euro-Collins solution.
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PMID:Single lung allotransplantation in pigs. A morphologic study of tissue preservation with modified Euro-Collins and fluorocarbon solutions. 236 Feb 50

Besides their cytotoxic effects, Tumor necrosis factor (TNF) and Lymphotoxin (LT) were shown to modulate distinct PMN functions. Therefore, in the present study we evaluated the effect of recombinant human TNF and LT on the oxidative metabolism of isolated human PMN. In addition ultrastructural changes upon stimulation were evaluated. For detection of granulocyte activation different assay systems were used: 1) lucigenin-dependent chemiluminescence (CL), 2) superoxide-dismutase (SOD) inhibitable cytochrome C-reduction (superoxide), 3) horseradish peroxidase-mediated oxidation of phenol red (hydrogen peroxide), 4) release of myeloperoxidase, 5) ultrastructural detection of hydrogen peroxide-production, 6) scanning and transmission electron microscopy (SEM and TEM). TNF at concentrations as low as 10(-3) U/ml induced a distinct CL response, whereas LT appeared to be less active. PMN preincubated with TNF or LT for 150 min were completely deactivated to renewed stimulation with TNF, LT, and with GM-CSF, but responded to other triggers of the oxidative burst. Moreover, stimulation with f-met-leu-phe resulted in an enhanced response after preincubation with TNF or LT. The CL response was significantly inhibited by SOD, but not by catalase, D-mannitol, and DMTU, suggesting that mainly .O2- is responsible for the CL signal. The effect on PMN could be completely blocked by antibodies to TNF. Significant release of reactive oxygen species upon stimulation with TNF was also demonstrated by cytochrome C reduction and by detection of H2O2 using functional and ultrastructural assays. Only minimal amounts of peroxidase were released. Activation of PMN could be visualized by SEM and TEM. After addition of TNF at concentrations as low as 10(-1) U/ml PMN adhered to the substratum and were typically polarized within 15 min. Stimulation with LT resulted in comparable results, but based on its biologic activity in the cytotoxicity assay LT, in comparison to TNF, was significantly less active. Based on the data presented LT and, particularly, TNF appear to be potent activators of PMN oxidative metabolism.
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PMID:Human tumor necrosis factor is a potent activator of the oxidative metabolism in human polymorphonuclear neutrophilic granulocytes: comparison with human lymphotoxin. 253 65

Lycobetaine (AT-1840), developed by our institute, is a new chemotherapeutic agent with relatively high percentage of remission on the treatment of ovary cancer and stomach cancer; no remarkable changes in blood picture, EKG and GPT, were observed. Early examination of the structure activity relationship of lycobetaine gave the following results: 1. A potential betaine and a methylenedioxy group in this compound may be critical for exhibiting antitumor activity; 2. Fission of the five membered ring of lycobetaine will not affect its antitumor activity. In order to see whether the distance between the phenolic oxygen and quaternary nitrogen affects its antitumor activity, compounds 7a-c, 8a-b were synthesized and screened against tumor in mice bearing EAC Preliminary experimental results showed that among the open ring analogs of lycobetaine, 7a, 7b and 8d possessed marked antitumor activity and 7c did not. The results indicate that changes in the distance of the betaine in lycobetaine obviously influence its antitumor activity.
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PMID:[Structure-activity-relationship study of the new anticancer drug lycobetaine (AT-1840)]. 281 92

Granulocyte-macrophage colony-stimulating factor (GM-CSF) was shown to modulate different granulocyte functions. In the present study we investigated the effect of purified and recombinant human GM-CSF, particularly on the oxidative metabolism of isolated human granulocytes. In addition, ultrastructural changes upon stimulation were evaluated. For detection of granulocyte activation the following assay systems were used: 1) lucigenin-dependent chemiluminescence (CL), 2) superoxide-dismutase (SOD) inhibitable cytochrome C-reduction (superoxide), 3) horseradish peroxidase-mediated oxidation of phenol red (hydrogen peroxide), 4) release of myeloperoxidase, 5) ultrastructural detection of hydrogen peroxide-production, and 6) scanning and transmission electron microscopy (SEM and TEM, respectively). A significant CL response was seen upon stimulation with recombinant human GM-CSF at concentrations ranging from 1 to 10(3) U/ml. The CL response started within 5-10 min with a maximum at 60-90 min and lasted more than 3 h. Thereafter granulocytes were completely deactivated to restimulation with the same mediator and with Tumor Necrosis Factor, but responded to other triggers of the oxidative burst, whereas the response to f-met-leu-phe was significantly increased. The CL signal was completely blocked by an antiserum to GM-CSF. Moreover, the response was significantly inhibited by SOD and D-Mannitol, suggesting the involvement of distinct reactive oxygen species (ROS) in generating the CL response. Significant amounts of superoxide were detected within 180 min after stimulation with GM-CSF, whereas release of hydrogen peroxide and peroxidase were only minimal as shown by functional and ultrastructural assays. Activation of granulocytes could be visualized by SEM and TEM. GM-CSF stimulated cells showed an increased adherence to the substratum developing polarized filopodia and an increased number of intracellular vesicles within 30 min after addition of the stimulus. The results clearly demonstrate that GM-CSF directly stimulates granulocytes and, particularly, their oxidative metabolism. Therefore, GM-CSF which is probably released by epidermal cells appears to be a candidate for neutrophil activation in the skin, and thereby may play a crucial role in inflammatory skin diseases.
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PMID:Human granulocyte-macrophage colony stimulating factor: an effective direct activator of human polymorphonuclear neutrophilic granulocytes. 283 54

To facilitate studies on the effect of chemotherapeutic agents on the host-parasite interaction in leishmaniasis, we have developed an experimental model for infecting mouse peritoneal macrophages in culture with recently-isolated Leishmania donovani promastigotes. As the drug action is often dependent on concentration, the distribution of sodium stibogluconate, which is the commonly used drug for treatment of leishmaniasis, was studied in various parts of the macrophages by energy dispersive X-ray microanalysis. The drug was found to accumulate in secondary lysosomes. The ultrastructural examination, using TEM and SEM, of macrophages, whose secondary lysosomes had been preloaded with gold particles, showed that leishmania parasites are phagocytosed and finally located in secondary lysosomes. Using flameless atomic absorption spectrophotometry, the concentration of Mn, Fe and Cu in promastigotes of Leishmania donovani, Leishmania aethiopica, Leishmania crithidia, Leishmania major and their culture media was estimated. Of the three transition metals, the parasites accumulated only Mn from the medium, which they may use in a primitive defense mechanism against reactive oxygen metabolites produced by macrophages during the respiratory burst associated with phagocytosis.
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PMID:An experimental model system for leishmaniasis. An ultrastructural study on cultured macrophages exposed to Leishmania parasites and sodium stibogluconate. 284 54

Results of tests on oxygen transfer rates and on a series of membranes, both in saline solutions and blood are reported. A series of hematological tests was carried out during the tests with blood, in order to assess the damage caused to the blood by contact with the membrane. All the results were compared with results obtained with the same equipment using Celgard membranes. A series of measurements at high liquid flow rate was carried out both with Celgard and the MFT membrane in order to eliminate the liquid-side resistance and evaluate the permeability of the membranes. The results of oxygen transfer rate into blood, when extrapolated by the "constant slope method" showed excellent agreement with the data obtained with saline solutions, justifying the use of oxygen absorption into saline during the process of screening membranes for use in blood oxygenators.
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PMID:Evaluation of a new type of membrane for blood oxygenation. 344 Jan 29

We have investigated, by scanning and transmission electron microscopy (SEM and TEM), the cell surface morphology of isolated human hepatocytes. For this purpose, liver cells were mechanically isolated from surgical or needle liver biopsies, fixed in 3% glutaraldehyde and post-fixed in 2% osmium tetroxide. In order to handle a low number of cells, a particular procedure for harvesting hepatocytes on coverslips has been developed for SEM and an in situ embedding procedure in polyethylene-embedding capsules was applied for TEM. A rough membrane exhibiting short, uniform microvilli and pores of 0.1 mu in diameter was the main feature of isolated liver cells. Furthermore, single hepatocytes showed no polarity and junctional or bile canaliculus remnants were rarely observed. However, differences in surface configuration were noted in relation to culture conditions, such as oxygen and temperature during isolation procedures. SEM, when controlled by TEM for intracellular preservation, is proposed as a reliable method for screening small quantities of hepatocyte suspensions, for intact cells and for the study of surface configuration under experimental conditions.
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PMID:Electron microscopy of isolated human hepatocytes. (Micromethods for scanning and transmission electron microscopy). 635 60


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