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Query: UMLS:C0276640 (TEM)
 20,729 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Study of corneal endothelium by scanning and transmission electron microscopy in two cases of corneal disease. In one case of herpetic keratitis with stromal oedema, there is no cellular reaction. The endothelium is damaged with cellular necrosis and nucleus irregularity. Intercellular junctions are abnormal. With TEM it is possible to say that there are two layers of cells on some places with cellular necrosis. In one case of corneal dryness with lesions of corneal anaesthesia the cells are very damaged and a retrocorneal membrane if formed by many layers of cells. The intercellular junctions are almost normal.
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PMID:[Electron microscopic study of the corneal endothelium in 2 cases of keratitis. Herpetic disciform keratitis. Neuroparalystic keratitis with dry keratitis]. 13 Aug 83

Changes in liver sinusoids following fractionated irradiation were studied by use of TEM and SEM. Rats received telecobalt-irradiation of their liver regions in daily doses of 500 r for 9 days, a total dose of 4500 r. One day after the end of the irradiation series the fine structure of hepatocytes was almost intact. In SEM the liver sinusoids contained numerous corpuscles, which in TEM were recognized as cellular blebs separated from endothelial cells. 8 days after irradiation small foci of necrotic hepatocytes could be visualized. Instead of complexes of small fenestrations (sieve plates) the endothelial cells contained striking round or oval holes in their tenuous processes. After 120 days small groups of hepatocytes with alterated fine structure of their organelles and some necrotic parenchyma cells were still present. Away from these focal necroses the endothelial cells now resembled sinusoidal endothelium in control animals. Fat-storing cells appeared to have multiplied and were enlarged. There was distinct fibrosis only in perisinusoidal spaces. The formation and discharge of electron lucent blebs is discussed as a mechanism compensating for an enhanced uptake of fluid into irradiation injured endothelial cells. In order to form holes in the tenuos processes of endothelial cells a disordered synthetic pattern and the shearing forces of the circulating blood are thought to be necessary. Repair of these intracellular holes may be possible. In rats irradiation induced lesions of the small intrahepatic vessels can be excluded as a cause of the late changes in liver parenchyma cells.
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PMID:[The liver sinusoids in rats following fractionated local telecobalt-irradiation. A transmission and scanning electron microscopic study (author's transl)]. 14 69

Primary mineralization in neoplastic tissue was studied in osteosarcoma, correlating observations obtained by SEM to those found with TEM. The process is characterized by extracellular matrix vesicles, distributed in the matrix between the forming neoplastic cells and the calcifying fronts. The occurrence of osmiophilic material and solitary hydroxyapatite crystals within the vesicles is followed by accumulation of apatite crystals, disappearance of the vesicular membrane and formation of calcospherites and calcified fronts. The process described here in neoplastic tissue is essentially similar to primary calcification in normal calcified tissues.
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PMID:The relationship between extracellular matrix vesicles and calcospherities in primary mineralization of neoplastic bone tissue. TEM and SEM studies on osteosarcoma. 15 92

Seventeen cancers from lung and pleura were studied with scanning, transmission electron, and light microscopy (SEM, TEM and LM). Diffuse mesothelioma mimics bronchioloalveolar carcinoma at LM but shaggy microvilli were found on the cellular surface of the former, and short sprouts densely packed or loosely scattered, on that of the latter. Neolumen formation was found in both. Oat cell carcinoma had a smooth surface with occasional tiny projections and minute surface depressions. The cellular projections of squamous cell carcinoma were quite irregular. Differentiation between diffuse mesothelioma and bronchioloalveolar carcinoma appears feasible with SEM in tissue appropriately fixed either with formaldehyde or glutaraldehyde. The role SEM can play in diagnostic pathology is yet to be explored.
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PMID:A scanning electron microscopic study of diffuse mesothelioma and some lung carcinomas. 19 41

The effect of temperature shiftdown on the assembly of ts3 virions was investigated by both scanning (SEM) and transmission (TEM) electron microscopy. Ts3 is a spontaneous temperature-sensitive mutant of Moloney murine leukemia virus (Mo-MuLV) which previous studies indicated to be defective in assembly or release of the virions. In the present study, both SEM and TEM revealed the following: (i) there were more cell-associated virions in ts3-infected cells grown at the nonpermissive temperature (39 degrees C) than either in cells grown at the permissive temperature (34 degrees C) or in wild-type MuLV-infected cells grown at 39 degrees C; (ii) there were more normal single particles than multiploids (virions with two or more pieces of genomic RNA) in ts3-infected cells grown at the nonpermissive temperature; (iii) there were more multiploids in ts3-infected cells grown at the nonpermissive temperature than either in cells grown at the permissive temperature or in wild-type MuLV-infected cells grown at the nonpermissive temperature; (iv) upon temperature shift from 39 to 34 degrees C, about 90% of the cell-associated virions dissociated from the cell surface. TEM studies also indicated that upon temperature shiftdown, virion assembly rapidly occurred. The above observations suggest that faulty assembly, which results in the production of multiploids, may not be the reason why ts3 virions accumulate on the cell surface at the nonpermissive temperature. The relatively higher proportion of multiploids found in ts3-infected cells grown at 39 degrees C compared with those grown at 34 degrees C may be due to the higher density of budding virions at the cell surface at the nonpermissive temperature, which increases the possibility of two or more particles assembling close to one another. The accumulation of ts3 virions in all stages of assembly at the nonpermissive temperature, together with the fact that rapid assembly and release of ts3 virions occurred on temperature shiftdown, indicates that virion assembly is restricted after it has been initiated. The probable role of altered glycoprotein(s) in restricting virion assembly is discussed.
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PMID:Electron microscopic characterization of the defectiveness of a temperature-sensitive mutant of Moloney murine leukemia virus restricted in assembly. 19 76

R938 carries a transposon (TAbeta) of approximate molecular weight 9.5 Megadaltons (Mdal, 10(6) daltons). This contains genes for a beta lactamase of type TEM-1 and for streptomycin phosphatransferase (SPT). There is a ten-fold difference in the efficiency of transposition in different strains of E. coli K12.
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PMID:Properties of a transposon conferring resistance to penicillins and streptomycin. 20 39

Infection with herpes simplex virus type 1 (HSV-1) induces different morphological changes in different cell lines. This is demonstrated by comparative scanning (SEM and transmission (TEM) electron microscopic investigations of cell cultures prepared under identical conditions. SEM of HSV-1 infected HEp-2 cells reveals a slightly altered cell surface: only the number of the microvilli is reduced. Large amounts of released virions are detectable adhering to the outer plasma membrane. Ultra-thin sections show typical virus maturation steps in the nuclei (formation of nucleocapsids and virus budding from the inner lamella of the nuclear membrane) and in the cytoplasm (egress of enveloped nucleocapsids through membranous structures). HSV-infected primary chick embryo fibroblast (CEF) cells are characterized by crumpled and rough surfaces without virus particles adhering to the membrane. Ultra-thin sections exhibit atypical virus maturation with many unenveloped nucleocapsids within the cytoplasm. The distribution of HSV-induced antigen(s) on the surface of the infected cells is identical in the two cell systems as determined by the peroxidase labelling technique. The c.p.e. (as seen by phase contrast light microscopy) is similar in both HEp-2 and CEF cells: both fusion and rounding up is induced in the infected cells.
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PMID:Differences in the morphology of herpes simplex virus infected cells: I. Comparative scanning and transmission electron microscopic studies on HSV-1 infected HEp-2 and chick embryo fibroblast cells. 23 Feb 92

Bone remodeling in pathologic conditions was studied with the scanning electron microscope (SEM). Benign and malignant ossification were examined in cases of myositis ossificans, ossifying fibroma, osteoid osteoma, and osteosarcoma, Resorption of bone due to invasion by non-ossifying tumors was found in cases of squamous cell carcinoma, adenocarcinoma, ameloblastoma, and multiple myeloma. Bone formation due to excessive production of growth hormone was studied in a case of acromegaly. Resorption of bone due to pathologic processes resembled the pattern found in surfaces which were undergoing resorption by osteoclasts. Lamelar-cortical bone formation in acromegally was similar in nature to normal bone. The deformities were rleated to the excessive continuous osteogenesis that occurs in these instances. Neoplastic ossification was characterized by calcifying globules, the diameters of which ranged from 1 to 3 micron. The surfaces of these globules were constructed of minute calcospherites with diameters ranging from 0.1 to 0.3 micron. It is suggested that the pattern of globular calcification is similar to the type that was found with the SEM in fetal bone and cartilage, during healing of fractured bone, and also with the TEM in normal and pathologic calcification.
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PMID:Bone remodeling in pathologic conditions. A scanning electron microscopic study. 26 94

In this paper the average diameter of enamel crystallites in mature, deciduous and fluorosed human enamel as well as in bovine enamel (in vivo and in vitro remineralized) is discussed. The investigation was carried out on broken surfaces of the various kinds of enamel with a scanning electron microscope. Corrections have been applied for the thickness of the gold-layer deposited. The average crystallite diameters for sound, deciduous and fluorosed human enamel were : 36 nm; 46 nm and 81 nm, respectively. The values for sound, remineralized in vitro and remineralized in vivo bovine enamel were 57 nm; 97 nm and 63 nm, respectively. The results indicate furthermore that if a correction for the sputtered goldlayer is applied, the results for SEM and TEM microscopy are in good agreement with each other. The difference between in vivo and in vitro remineralized bovine enamel is most likely due to differences in speed of remineralization and/or the presence of saliva.
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PMID:Crystallites dimensions of enamel. 28 86

The program QTHIN combines those methods for processing energy-dispersive X-ray spectra and computing concentrations best suited to thin section microanalysis in TEM or STEM. The program is in BASIC, and so can be modified (for instance for unusual geometries, other matrices such as oxides, etc.). It is suitable for routine use on complex samples with peak overlaps, and for "not-so-thin" samples in which absorption is not negligible.
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PMID:A BASIC-language program for dedicated energy-dispersive microanalysis of thin samples in TEM or STEM. 29 76


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