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

Picric acid-paraformaldehyde-glutaraldehyde (PA-P-G) was used to stabilize chemically ocular surface-associated mucus in mice of various ages. Transmission electron microscopy was then used to examine those specimens stained with cationic ferritin (CF), dialysed iron and Alcian Blue. Collectively, all of these stains are markers for anionic sulfate or carboxyl groups. With each of them, positive labeling of the ocular surface was observed for all ages examined, even when mucus cannot be morphologically demonstrated. Except for dialysed iron, staining was weak in the youngest animals and heaviest in young adult and aged mice. The ocular surface was negative for high iron diamine (HID) in pups and older mice through 1 year of age. Scant positive staining for HID was seen at the ocular surface in 14-month-old mice indicating that mucus became slightly sulfated with aging. Treatment of eyes with neuraminidase prior to fixation reduced the number of CF binding sites in all ages of mice examined, confirming that many of the carboxyl groups at the ocular surface are associated with sialic acid residues. Comparison of percentage reduction in CF labeling following neuraminidase treatment of the eyes of 5- and 10-postnatal day mice with all other ages of mice suggested that fewer removable carboxyl groups at the ocular surface are associated with sialic acid residues in pups. The ocular surface of all eyes also stained positively at the TEM level when a periodic acid-thiocarbohydrazide-silver protein (PA-T-SP) staining sequence was used. Collectively, these data are of significance with respect to further characterization of the ocular surface, particularly with regard to development-associated changes and their possible role in defence of the eye surface.
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PMID:Ocular surface complex carbohydrates are modified with aging. 243 68

Cultured human glial cells constitute a suitable model system for the study of lipofuscinogenesis in vitro. These cells, although not post-mitotic, can be kept for several months in stable monolayers due to their display of very pronounced density-dependent inhibition of cell growth. Residual bodies, or lipofuscin pigment granules, accumulate over time in this "pseudo" post-mitotic cell system. I. In early dense cultures, exposed to purified rat liver mitochondriae, it was possible to follow the uptake of mitochondriae and their degradation, which was found to be incomplete and result in the formation of numerous residual bodies containing lipofuscin-type material. It was concluded that incomplete degradation of mitochondriae may be an important origin of lipofuscin. II. Dense, older cultures exposed to electron dense marker particles (colloidal thorium dioxide) accumulated these markers within endosomes, and later in secondary lysosomes of various types, including residual bodies. It was concluded that residual bodies constitute an integral part of the lysosomal vacuome system. III. Phase III glial cells were cultured on formvar-coated gold EM-grids and studied by whole cell transmission electron microscopy using TEM and STEM techniques in combination with energy dispersive X-ray microanalysis. It was found that residual bodies contained iron. This fact was taken as a further indication that lipofuscin has its origin in autophagocytosed mitochondriae and ER-material rich in metallo-enzymes. Due to their high concentration of iron, residual bodies may constitute unstable structures within the cells. Since iron is a well known catalyst of various peroxidative processes, the surrounding lysosomal membrane might be damaged, e.g. by oxidative stress, with risk for leakage of degradative lysosomal enzymes into the cell sap.
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PMID:On the origin of lipofuscin; the iron content of residual bodies, and the relation of these organelles to the lysosomal vacuome. A study on cultured human glial cells. 248 59

In a 37 years-old female worker, who had undergone surgical excision of a segment of the right lower lobe for a chronic aspecific pleuropneumonitis, the histological examination of the excised lung tissue showed asbestos alveolitis with diffuse interstitial fibrosis, and multiple granulomata containing talc particles. An investigation at the work site showed that the worker had been engaged for 22 years in dusting salami with a mixture of rice flour and talc contaminated with chrysotile asbestos. Thirteen work-mates engaged in the same job were studied. In two of them, with chest X-rays negative for pneumoconiosis, a functional ventilatory impairment, restrictive in type, associated with a reduced pulmonary diffusion of gases, was demonstrated. In these two cases, bronchoalveolar lavage showed signs of severe exposure to asbestos (which at TEM evaluation resulted to be amphibolic) talc and other fibres, with presence of iron-laden macrophages, indicators of haemorrhagic alveolitis. Moreover, in one of them, a severe macrophagic-lymphocytic alveolitis, with inverted T helper/T suppressor ratio, was presented, possible expression of a hypersensitivity pulmonary reaction. Taking into consideration the length and modality of work, with exposure to talc powder contaminated with asbestos, for the three cases the diagnosis of "pre-radiologic talcosis-asbestosis" was made. Since the occupational risk was not known in this industry, no ambient and personal preventive and protective measures had been taken; anyway, such type of work has now been stopped. The exposed workers shall be kept under control in the future for surveillance directed towards early diagnosis of possible further asbestos effects.
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PMID:[Talcosis-asbestosis: an unusual risk in a food industry]. 315 50

We used concanavalin A (con A)-peroxidase-iron dextran-diaminobenzidine (DAB) technique for the electron microscopic detection of con A binding sites on cell membranes. Normal bladder mucosa showed a sparse distribution of con A binding sites with both transmission (TEM) and scanning (SEM) electron microscopy, but bladder tumors showed a higher concentration in the distribution of con A binding sites in proportion to the histopathological grade of transitional cell carcinoma. Quantitative estimation of the con A binding sites was attempted using scanning X-ray pulse analysis of iron elements contained in the reaction complexes. Con A binding sites were quantitatively the smallest in normal mucosa, increasing proportionate to the grade of the bladder tumor. Some specimens were compared by the ferritin-labelled method and the pattern of ferritin conjugates distribution was similar to that seen with the con A-peroxidase-iron dextran method.
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PMID:Distribution of concanavalin A binding sites on normal human urinary bladder mucosa and bladder tumors by transmission and scanning electron microscopy and X-ray microanalysis. 674 Aug 37

Secondary lysosomes of the residual body type are frequent in nondividing cells from phase III cultures of human glial cells. These organelles have previously been shown to be analogous to lipofuscin granules of postmitotic cells in vivo. Most recent studies favor the assumption that residual bodies mainly result from incomplete degradation within the lysosomal vacuome of endogenous cellular components such as mitochondria and endoplasmic reticulum. Since iron occurs in several metalloenzymes produced by such organelles, it should then be possible to demonstrate accumulated iron within residual bodies. X-ray dispersive analysis of sectioned biological material is often hampered by diffusion and dissolution during preparation, as well as by too low a concentration of the elements. In this study we cultured glial cells on Formvar-coated gold grids and studied them unsectioned, after brief glutaraldehyde fixation and freeze-drying, in a transmission electron microscope at 100 kV in TEM and STEM mode. It was then possible to demonstrate iron in residual bodies of aged cells, presumably because the type of preparation utilized does not permit much dissolution.
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PMID:Electron probe X-ray microanalysis of residual bodies in aged cultured human glial cells. 723 72

The formability of galvanneal steel sheets used in the automotive industry is influenced by the presence and distribution of brittle and difficult to distinguish Zn-Fe intermetallics in the coating. Characterization of these intermetallics requires a high spatial resolution technique such as analytical transmission electron microscopy (ATEM). Sample preparation by ion milling is impossible due to iron redeposition, and traditional ultramicrotomy using water affects the coating chemistry. A technique based on dry ultramicrotomy has therefore been developed. To optimize the technique, different parameters (knife angle, cutting medium, thickness setting on the ultramicrotome, cutting speed) have been investigated for the preparation of galvanneal coatings and pure A1 sections. Results show that dry cutting does not affect the coating chemistry but shortens the life of the knife. Knife quality (cleanliness, sharpness and absence of defects) is a major factor to obtain good dry sections. The best results for the more ductile pure A1 are obtained with a 35 degrees knife whilst for the harder galvanneal coating it is recommended to use a 55 degrees knife. These results suggest that the sectioning mechanism for the harder material involves more a cleavage-fracture mechanism whilst a greater amount of shear is involved when sectioning relatively ductile A1. The optimum parameters for sectioning galvanneal coatings are established and results obtained by parallel electron energy loss spectrum imaging and energy dispersive X-ray spectrometry in the TEM are given. This study shows that with a good control of all the sectioning parameters it is possible to obtain good sections repeatedly and rapidly.
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PMID:Development and application of a dry ultramicrotomy technique for the preparation of galvanneal sheet coatings. 754 2

A patient was referred to the Charles Clifford Dental Hospital with a grey metallic pigmentation of the hard palate. Conventional histopathological examination was inconclusive, suggesting the presence of either an ephelis (freckle) or pigmentation resulting from a stainless steel upper denture. Material from the pathological specimen was dewaxed and reembedded in Spurr's resin. Examination in the TEM revealed electron dense deposits in the cytoplasm of macrophages. Energy dispersive X-ray microanalysis demonstrated that these inclusions contained iron. The results suggested that the iron was in a form similar to haemosiderin and had arisen from the steel denture.
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PMID:X-ray microanalytical detection of iron in pigmentation of oral mucosa. 837 6

Suspensions of coated superparamagnetic particles (magnetic fluids, MF) in AC magnetic fields have a pronounced specific absorption rate (SAR) per mass compared to multidomain particles. The aim of the present study was to investigate cellular uptake and the biological effects of AC magnetic field excited bio-compatible magnetic fluids on human carcinoma cells in vitro. One of the fluids tested was a dextran magnetite, which has a very low cyto-toxicity with survival fractions (SF) between 0.8 and 0.9 at concentrations of up to 5 mg ferrite per ml. Human carcinoma cells intracellularly accumulate up to 1 pg ferrite/cell which has been demonstrated by electron microscopy (TEM), X-ray spectroscopy and measurements of intracellular iron. It has been shown that the ferrite core is not altered intracellularly, but many of the dextran shells are degraded which yields particle chains and other aggregates observed in TEM. Semi-solid pellets of the tumour cells were treated with AC magnetic fields (520 kHz, 4-12.5 kA/m) or waterbath hyperthermia at 43 and 45 degrees C, in presence of extracellular and/or intracellular magnetic fluid particles. Although MF heating is produced from individual particles, the survival fractions of MF heated and water bath heated cells are equal. In fact, the extracellular MF particle distribution is homogeneous enough to obtain similar inactivation. In contrast to earlier reports intracellular dextran magnetite particles in AC magnetic fields did not induce cell inactivation. Since the amount of intracellular ferrite should be indeed large enough for cell inactivation, the loss of dextran shells is most probably the main cause of limited effectiveness of the intracellular magnetite particles. The present work has demonstrated that: (1) MFH is able to inactivate tumour cells in vitro to at least the same extent as water bath hyperthermia; and (2) that there is a sensitizer effect of ferrofluids at 43 degrees C probably caused by free ferric ions which induce oxidative stress; and (3) that there is no cytotoxic effect of intracellular dextran magnetite particles 30-180 min excited with AC magnetic fields used in this study. For the new method the term 'magnetic fluid hyperthermia (MFH)' is proposed.
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PMID:Cellular uptake of magnetic fluid particles and their effects on human adenocarcinoma cells exposed to AC magnetic fields in vitro. 895 Jan 52

Some ambiguity is still involved in the interpretation of the growth mechanism of monodispersed hematite (alpha-Fe2O3) particles in dilute FeCl3 solutions. Namely, there are two entirely different proposals on this issue, viz. aggregation of preformed primary particles of alpha-Fe2O3 itself and reprecipitation of the ionic species through dissolution of the preformed beta-FeOOH particles. In order to resolve this problem, the formation process was followed in detail through TEM, Electron Diffraction, XRD, FT-IR, and ICP spectrometry along with quantitative analyses on seed effects. As a result, it has been concluded that the nuclei of the hematite particles are initially generated with the formation of beta-FeOOH particles and that they are grown by deposition of the solute originally present in the solution phase and indirectly furnished from the beta-FeOOH by dissolution. As the concentration of the solute is lowered by the growth of the hematite particles, they continue to grow with the solute provided mainly from the beta-FeOOH in a steady-state of the dissolution of beta-FeOOH and growth of alpha-Fe2O3. The basic formation mechanism is common to the ellipsoidal particles grown in the presence of phosphate ions and spherical particles in their absence.
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PMID:Formation Mechanism of Monodispersed alpha-Fe2O3 Particles in Dilute FeCl3 Solutions 897 68

In situ functional assay of each ferritin molecule in single-layer 2D arrays for horse spleen apoferritin and recombinant horse L- and human H-apoferritins was conducted by observing the iron-cores formed in the arrays by TEM. The study of the time-course, pH-dependence, and temperature-dependence of the function confirmed the iron-core formation to be due to the native function of apoferritins in array. Dark-field TEM imaging revealed that there was crystallinity in the cores in the array of recombinant human H-apoferritin. This iron-core formation was perfectly preserved in the array even after 3 months of storage at room temperature and low humidity. Moreover, about 50% of the function was found to remain in the array after it was exposed to 150 degrees C in vacuum for 1 hr.
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PMID:Single molecular functional assay of ferritin arrays. 920 35


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