Observations of plate-like crystals in human dental calculus.
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Calcium Phosphates↗
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[Disordered mineralization process in hard dental tissues and the principles of its regulation].
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Adolescent↗
Calcium detection in secretion granules of avian oviduct by scanning electron microscopy (SEM) and energy-dispersive X-ray microanalysis (EDX).
Secretion granules in the shell gland, isthmus, and albumin-secreting region of the hen oviduct were analyzed with WET-scanning electron microscopy (SEM) and EDX, a combination of wide-angle backscattered electron detector (BED) and energy-dispersive X-ray microanalyzer (EDX). Glutaraldehyde-fixed but unhydrated, unstained, and uncoated samples were analyzed; Ca was localized in all secretion granules in all three sections of the hen oviduct studied.
Animals↗
Comparison of analytic techniques: chemical, isotopic, and microprobe analyses.
The development of new techniques and modifications to existing methods are providing important information about cellular water and electrolytes in relation to transepithelial transport. Information obtained for one epithelium, the toad urinary bladder, from chemical analyses, isotopic studies, and electron microprobe analysis, is reviewed. Chemical and isotopic analyses allow estimation of average cellular water and ion contents and determination of the origin of ions from the media bathing the mucosal and basolateral cellular membranes. The electron microprobe provides additional information about the distributions of ions between the cell types that constitute the epithelial layer and also allows some measurement of ion distributions within individual cells. In toad urinary bladder epithelial cells there is broad agreement between the results obtained with these different techniques and a summary is provided of possible relationships between transepithelial sodium transport and cellular composition.
Animals↗
Elemental and ultrastructural analysis of specific human lens opacities.
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Cataract↗
Cryoultramicrotomy, electron probe microanalysis and STEM of myocardial tissue.
Heart muscle preparations (papillary muscles and trabeculae) were frozen at 4.2 K on metal plate under vaccum after their length-tension relationships showed that no damage had occurred during dissecting and mounting the strips on the holder. Freeze substitution of some preparations directly after freezing demonstrated that no important cell damage due to ice crystals occurred in superficial cell layers during freezing. Ultrathin cryosections obtained at -130 degrees C were freeze dried and analyzed, in the STEM mode. The better the freezing procedure, the poorer was the contrast of the sections under electron microscopy. Preliminary approaches to increasing contrast after sublimation of tissue water show that a small increase in contrast is generally obtained at the cost of the peak/background ratio due to pronounced mass loss. The results of our analyses show that C1 content in heart muscle cells is high and distributed throughout the cytoplasm. Ca is detectable and quantitable in resting muscle in SR cisternae. The Ca amount in cytoplasm is low and just at the limit of detectability under our current analysis conditions. Preliminary experiments on papillary muscles subjected to caffeine contracture showed that calcium is not detectable in the cisternae as is the case in control experiments. Only a moderate amount of Ca is detectable in mitochondria, whereas the concentrations in cytoplasm, as in resting cardiac muscle, is too low to be quantitated.
Animals↗
[The mapping of the local content of water and dry matter by using ultrathin frozen sections].
The possibility and applications of quantitative dry mass and water content mapping using an image analysis of darkfield intensity digitalization were shown on ultrathin freeze-dried cryosections. The distribution map obtained may be further used both for direct measurements of local dry mass and water content under physiological state and pathological disorders and for calculation of the concentration values obtained by quantitative X-ray mapping on freeze-dried cryosections in terms of millimoles per litre of cellular water.
Analog-Digital Conversion↗
Argyria: microanalytic-morphologic correlation using paraffin-embedded tissue.
Scanning electron microscopes, which have energy dispersive spectroscopy (x-ray microanalysis) capability, can provide accurate identification of the composition of inorganic deposits in tissue. We report a case of florid argyria in which the same deparaffinized 4-micron sections were sequentially examined by light microscopy, scanning electron microscopy, backscattered electron imaging, and x-ray microanalysis to confirm the clinical impression of argyria. We recommend the use of x-ray microanalysis of paraffin-embedded tissue as a simple, rapid and inexpensive means of precise identification of inorganic deposits of heavy elements in tissue sections.
Administration, Intranasal↗
Light elements quantification in stimulated cells cryosections studied by electron probe microanalysis.
The quantification of intracellular light elements such as carbon, nitrogen and oxygen may be useful in understanding the biological mechanisms, for example the generation of nitric oxide which is involved in apoptosis and inflammatory reaction. Electron energy loss spectroscopy (EELS) coupled with scanning transmission electron microscopy is a useful method to detect light elements in thin cryosections. Recent developments of X-ray detectors with ultra-thin protection windows allows the detection of such elements by energy dispersive X-ray spectroscopy. In the present study, we have demonstrated using both methods that the stimulation of BV-2 murine microglial cell line by gamma-interferon and lipopolysaccharide leads to the increase of intracellular oxygen concentration and no change in the intracellular nitrogen concentration. This indicates the use of exogeneous molecular oxygen in response to the stimulation. But the increase of oxygen concentration detected could not be only due to NO expression because the NO production was 1000 times less than the oxygen concentration increase observed.
Animals↗
[Contribution of x-ray microanalysis to the study of the growth of a urinary calculus].
Growth mechanisms of urinary calculi were studied using a scanning electron microscope (SEM) and an x-ray microanalyser (WDS). The observations obtained by SEM and x-ray mapping suggest with calcium, phosphorus, magnesium, sulfur and potassium a possible schema of growth mechanisms for urinary calculi.
Calcium↗
Ultrastructural properties of bone mineral of control and tiludronate-treated osteoporotic rat.
Bisphosphonates have been widely used in the treatment of human bone pathologies including osteoporosis. In this case, bisphosphonates have been shown to reduce bone resorption, thereby increasing the mass and mechanical resistance of bone. Determining the effects of these molecules on the properties of the bone apatite crystals could provide a better insight into the mechanism of bisphosphonate/bone interaction. The aim of this study was to determine the ultrastructural effects of a third generation bisphosphonate (tiludronate) on the morphology, size, distribution, chemical composition, and structure of apatite crystals in bone (trabecular) in a rat osteoporotic model. Four groups of rats were studied: (1) sham operated, (2) untreated ovariectomized (OVX), (3) OVX rats which received 35 mg/kg of tiludronate, (4) OVX rats which received 160 mg/kg of tiludronate. The rats of groups 3 and 4 received tiludronate orally in 2 consecutive days every week for 1 year. Scanning electron microscopy (SEM), high and low resolution transmission electron microscopy (TEM), and electron microprobe analysis (EDX) were used for the ultrastructural characterization of the bone mineral. This study demonstrated that tiludronate slightly increased the width of bone apatite crystals without changing any other crystal characteristics.
Animals↗
Contact formation dynamics: Mapping chemical bond formation between a molecule and a metallic probe.
We present a study that maps out chemical bond formation between a Pt-inked probe and a single 1,3-cyclohexadiene (1,3-CHD) molecule on Si(100). By separating the mechanical and electronic contributions to the current during the approach to contact, we show that there are significant forces between the probe and the C=C of the molecule and we track the relaxation of the molecule, the emergence of a chemical bond feature in the LDOS, and the quenching of specific molecular vibrations during bond formation.
Binding Sites↗
Titanium alloy cylinders in implant framework fabrication: a study of the cylinder-alloy interface.
Titanium alloy has been proposed as a suitable alternative to noble metal alloys in premanufactured metal cylinders for fabricating implant prosthesis frameworks. The interfaces produced by standard lost wax procedures that use titanium and conventional noble metal implant cylinders with both high-fusing (high-palladium) and low-fusing (high-gold) noble metal casting alloys were compared. Elemental analysis by scanning electron microscopy and energy-dispersive spectroscopy (SEM/EDS) of the two titanium cylinders revealed that one commercial product had a composition similar to that for commercially pure titanium and the other had a composition consistent with that for Ti-6Al-4V alloy. The SEM observations and complementary elemental line scans indicated that the interfaces between the titanium cylinders and the two noble metal casting alloys did not meet proposed criteria for acceptable metal-to-metal unions. The interfaces between the noble metal cylinders and noble metal casting alloys did exhibit acceptable unions. The SEM observations and elemental analyses were supported by push-shear test results that showed that the resistance to failure was appreciably greater for interface specimens produced with alloy cast to noble metal cylinders compared with titanium cylinders.
Alloys↗
Tangential flow filtration and preliminary phylogenetic analysis of marine picoplankton.
A procedure was developed for harvesting gram quantities of microbial biomass from oligotrophic waters, when mixed populations are present in low abundance. Picoplankton from Atlantic Ocean (Hydrostation S, Sargasso Sea) and Pacific Ocean (Aloha Station) sites were collected in a three-stage process: (i) collection of seawater through an intake covered with 10-microns-pore Nytex; (ii) concentration by a tangential flow filtration device equipped with 10 ft2 (0.929 m2) of 0.1-micron-pore fluorocarbon membrane; (iii) collection of cells from concentrate by centrifugation. The overall efficiency of picoplankton recovery was at least 37%. The cellular morphotypes recovered matched those of the original population. DNA was prepared from frozen cell pellets by enzymatic digestion, solvent extraction, and isopycnic centrifugation. As indicated by the binding of kingdom-specific hybridization probes to the purified DNA, the Sargasso Sea picoplankton in this collection were largely eubacteria.
Animals↗
[Surface analysis and metallographic studies of Judet's prosthesis].
Surveying a quantity of 25 prostheses type Judet by stereoscopy and scanning electron microscopy in all specimen contaminations of the surface were found. By X-ray microanalysis these contaminations were ascertained to be mainly residues of the casting mould. Furthermore, tooling residues from the sandblast (e.g. grains of corundum or glass) were found. A metallographic investigation, which was performed thereupon on two randomly selected specimen, shows clusters of microporosities in the cross sections and carbides in the grain boundaries.
Electron Probe Microanalysis↗
Identification of a foreign body using energy dispersive x-ray analysis.
A foreign object, presumably swallowed during a dental appointment, was recovered by using an esophagoscope and thought to be a piece of dental impression material, probably alginate. It was identified as being of nondental origin by means of visible light and scanning electron microscopy (SEM), the latter coupled to an energy dispersive X-ray analyzer. Histologic examination revealed some amorphous crystalline material surrounded by parakeratin and exfoliated squamous cells. The material was essentially radiolucent. A known dental alginate impression material contained diatomaceous earth filler (siliceous shells of diatoms), but no microscopic symmetrical figures were seen in the foreign body. After dehydration, both materials were carbon-coated and observed in an SEM at 20 kV at magnifications up to 2000 X. The spectrum of secondary X-rays produced by the scanning electron beam revealed only magnesium in the foreign body and mostly silicon in the dental alginate. There are no known dental products that contain magnesium as the only inorganic ingredient and so the foreign body is believed to be not of dental origin. The patient may have had an antacid or laxative having magnesium as a major ingredient in the stomach, and this may have been refluxed from the stomach after stimulation of the normal gag reflex during the dental procedure.
Dental Materials↗
[Analysis of the effects of physico-chemical factors on the stability of lead and mercury levels in biological specimens. I. Biological specimens with the addition of Pb and Hg standards].
For the analysis of the process of precipitation and adsorption in the walls of polyethylene and glass vessels in which biological specimens containing mercury and lead were stored, the techniques of scanning electrone microscopy and X-ray microanalysis were applied. It was observed that the losses of: --lead in stored urine specimens were mainly due to precipitation, --mercury in stored urine specimens occur, among others, through adsorption on vessels' walls. X-ray microanalysis may also facilitate determination of the chemical composition of micro-structural fragments deposited on the surface of vessels.
Adhesiveness↗
Calcite sputum lith. Characterization by analytic scanning electron microscopy and X-ray diffraction.
The chemical identification by x-ray diffraction and analytic scanning electron microscopy of a sputum lith weighing 1 mg is described. These technics demonstrated that the lith was composed of rhombohedral calcium carbonate (calcite). Since different crystal species form under different chemical conditions, these precise, nondestructive analytic technics should have wide application in the investigation not only of a bronchial liths but also of other microcrystalline tissue deposits.
Adult↗