Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Electron Probe Microanalysis”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,675 records · Page 93Linked to original sources
PubMed1991

Calcium pyrophosphate dihydrate deposition disease: morphological and microanalytical features.

The light microscopic and polarization appearances of calcium pyrophosphate dihydrate crystal deposits in tissues are reviewed. In routine sections haematoxylinophilic crystalline deposits with a feathery or brush-like pattern are typical of calcium pyrophosphate dihydrate. Short rhomboidal crystals showing positive birefringence are seen on polarization; X-ray microanalytical and infrared spectroscopic data support the specificity of these appearances. The appearances of the crystal deposits in decalcified specimens are also described. We include six cases of calcium pyrophosphate dihydrate deposition within periarticular bone; to the best of our knowledge this has not previously been described.

Aged↗
PubMed1977

The use of PIPES buffer in the fixation of mammalian and marine tissues for electron microscopy.

PIPES, an organic based buffer, was used in the preparation of a variety of marine and mammalian tissues for electron microscopic study. The ultrastructural results demonstrate that this buffer renders superior ultrastructural details to those obtained with some of the more common inorganic buffers especially when long fixation times are required. Furthermore, this buffer system does not appear to contribute extraneous anions or cations to the tissues and thus permits accurate elemental determinations to be performed on thin sections of the plastic embedded specimens by means of energy dispersive X-ray analysis.

Animals↗
PubMed1986

Why low temperature embedding for X-ray microanalytical investigations? A comparison of recently used preparation methods.

Freeze-drying followed by infiltration with resin and polymerization by UV light at low temperatures and under constant vacuum conditions is an alternative tissue preparation technique for microprobe analysis. Embedding is carried out with the nonpolar low-temperature embedding resin (Lowicryl HM20) which allows infiltration and polymerization at temperatures down to -50 degrees C. Sections of low temperature embedded material can be cut dry at -60 degrees C or at room temperature. Sectioning at low temperatures is an alternative for preparations that are difficult to cut at room temperature. The morphological preservation is adequate for the identification of structures such as mitochondria, lysosomes and different types of endoplasmic reticulum in liver cells. Some physical properties of Lowicryl resins, such as mass loss under the electron beam and high contrast, are positive characteristics for the analysis of semi-thick sections. No significant differences in the elemental composition could be detected between tissue which was freeze-dried or freeze-substituted prior to embedding. Freeze-drying is less time consuming. By avoiding contact with organic solvents the risks of ion loss and redistribution are diminished. In contrast to freeze-dried thin cryosections, low temperature embedded material can be sectioned for light microscopy and areas of interest chosen for further thin sectioning. This is of great importance in work with tissues with complicated morphology and heterogeneous cell populations. The initial preparative step--the cryofixation--determines to a high degree the morphological preservation of freeze-dried and embedded tissue.

Animals↗
PubMed1990

Cu-Ti, Co-Ti and Ni-Ti systems: corrosion and microhardness.

Titanium alloys of 10 wt%-72 wt% Cu, 10 wt%-80 wt% Co and 20 wt%-84 wt% Ni were investigated. Ingots were fabricated in a vacuum/argon tungsten arc furnace. The surfaces of the alloys were examined by optical microscopy and SEM/EDS, and the Knoop hardness values of the alloys were measured. The corrosion resistance of the alloys was determined by a potentiodynamic polarization technique in buffered Ringer's solution. When a threshold composition of 30 wt% alloy was reached, a large decrease in corrosion resistance was found to occur. Knoop hardness measurements showed that similar hardness values of approximately 300 KHN can be obtained in all systems with lower alloy content. These values are similar to those obtained with a commercial dental titanium alloy.

Chemical Phenomena↗
PubMed1990

Etched glass ionomer liners: surface properties and interfacial profile with composite resins.

The purpose of this study was to assess the surface alterations induced by acid etching on two glass ionomer lining cements (Ketac Bond, G-C lining cement) and to evaluate their interface with a composite resin (Herculite XR) following various surface treatments. The changes in the surface composition and topography of the etched liners were studied by electron microprobe and ESCA analyses. The interfacial treatments performed on the ionomer surfaces were: (i) application of a bonding resin; (ii) 20-s acid etching and application of a bonding resin; (iii) application of a dental adhesive based on a chlorophosphate ester of BisGMA (Scotch-bond LC), without acid etching. The interfacial sealing efficiency of these treatments was studied by the silver nitrate microleakage technique combined with optical and electron microscopy. According to the results the etched surfaces of both the liners present excessive porosity with glass and matrix dissolution. Significant changes in the surface chemistry of the liners were detected indicating severe degradation. The microleakage study revealed interfacial gaps and fractures in the etched samples. The best results were obtained from the non-etched ionomer liners which were subjected to the adhesive treatment. The efficiency of acid etching as a necessary step in the 'layered' technique is seriously questioned.

Acid Etching, Dental↗
PubMed1993

Radiopacity of 12 visible-light-cured dental composite resins.

The radiopacity of 12 VL-cured composite resins was determined with reference to an aluminum step-wedge. Two anterior composites were radiolucent while two anterior and one anterior/posterior composites exhibited the radiopacity equal to, or slightly greater than, that of human enamel. Three posterior and one inlay composites possessed the radiopacity equivalent to, or in tiny excess of, that of human enamel. Three posterior composites had the radiopacity, fairly exceeding that of human enamel. Chemical analyses of the filler particles were carried out with SEM/EDX. It became evident that radiopaque fillers contained at least one radiopaque oxide component such as BaO, ZrO2 and Yb2O3 with varying concentrations. In general, the radiopacity of the composite resin was linearly proportional to the amount of the radiopaque oxide in the filler. It was suggested that ZrO2 was radiopacifier equivalent to, or even stronger than, BaO.

Composite Resins↗
PubMed1983

Orcein positive hepatocellular material in the liver. With special reference to its relationship with human lipofuscin.

Histopathological relationship between orcein positive hepatocellular material (ophm) reported by Sipponen and human lipofuscin (hlp) was investigated. Ophm was found to be very similar to hlp of the liver as well as of heart muscle cell morphologically and histochemically, and it seems to be quite rational to consider that ophm may be a substance which belongs to the lysosome series comprising hlp and prelipofuscin. Ophm has been discussed often from a view point of copper contents, which was considered to be one of its specific characters, but it has become clear that hlp can also possess copper according to our investigation and to some reports of other researchers. This fact throws a doubt on the significance of the specific relation between ophm and copper, as well as the usability of orcein stain for detecting copper in histological specimens. Victoria blue stain is quite useful for the detection of hlp including ophm, since it gives a blue color for it with a good contrast against red colored cytoplasm and nucleus. However, this can not be considered as a method for specific stain of copper either.

Electron Probe Microanalysis↗
PubMed1988

Distribution of elements in rat peripheral axons and nerve cell bodies determined by x-ray microprobe analysis.

X-ray microprobe analysis was used to determine concentrations (millimoles of element per kilogram dry weight) of Na, P, Cl, K, and Ca in cellular compartments of frozen, unfixed sections of rat sciatic and tibial nerves and dorsal root ganglion (DRG). Five compartments were examined in peripheral nerve (axoplasm, mitochondria, myelin, extraaxonal space, and Schwann cell cytoplasm), and four were analyzed in DRG nerve cell bodies (cytoplasm, mitochondria, nucleus, and nucleolus). Each morphological compartment exhibited characteristic concentrations of elements. The extraaxonal space contained high concentrations of Na, Cl, and Ca, whereas intraaxonal compartments exhibited lower concentrations of these elements but relatively high K contents. Nerve axoplasm and axonal mitochondria had similar elemental profiles, and both compartments displayed proximodistal gradients of decreasing levels of K, Cl, and, to some extent, Na. Myelin had a selectively high P concentration with low levels of other elements. The elemental concentrations of Schwann cell cytoplasm and DRG were similar, but both were different from that of axoplasm, in that K and Cl were markedly lower whereas P was higher. DRG cell nuclei contained substantially higher K levels than cytoplasm. The subcellular distribution of elements was clearly shown by color-coded images generated by computer-directed digital x-ray imaging. The results of this study demonstrate characteristic elemental distributions for each anatomical compartment, which doubtless reflect nerve cell structure and function.

Animals↗
PubMed1993

Aluminum tattoo: a phenomenon that can resemble parasitized histiocytes.

We present a study of aluminum tattoos that resulted from aluminum chloride cauterization of biopsy sites. The stippled macrophages were studied by light and electron microscopy and by means of X-ray energy spectroscopy (XES) analysis. The light microscopic appearance may be striking, and may mimic the appearance of parasitized histiocytes, although the particles are larger and vary in size and shape. The basophilic particles are electron dense by electron microscopy. XES analysis demonstrated distinct emission peaks corresponding to aluminum, calcium, and phosphorus. Only a minor chloride emission peak was identified. The particles may represent an inorganic precipitate or an organic compound in which aluminum, calcium, and phosphate form a complex with protein.

Aluminum↗
PubMed2000

Ultrastructural study of direct bone formation induced by BMPs-collagen complex implanted into an ectopic site.

OBJECTIVE: Some authors have reported that direct bone formation is ectopically induced by bone morphogenetic proteins (BMPs) independently of cartilage formation when type I collagen is used as a carrier. This study ultrastructurally investigated the mechanism of direct bone formation by BMPs-collagen complex. MATERIALS AND METHODS: Partially purified BMPs were combined with atelopeptide type I collagen (AC) and were implanted into the calf muscles of rats (n = 20). Tissue specimens were removed on days 7, 10, 14, and 21 after implantation. RESULTS: Ultrastructurally, several regions near the pellet rim showed evidence of early calcification on day 10. In the uncalcified regions, mitochondrial calcification was seen in mesenchymal cells near AC fibers. The initially calcified regions contained numerous calcified granules deposited in the AC fibers. Some of these granules adhered to the cell membrane of osteogenic cells. In the highly calcified regions, some osteogenic cells secreted uncalcified matrix and deposited needle-like crystals and calcified collagen microfibrils on the AC fibers. CONCLUSION: This study suggests that the mesenchymal cells invading BMPs-AC complex closely contacted the AC fibers, differentiated into osteogenic cells, and deposited calcified matrix on the AC fibers, resulting in direct osteoinduction without cartilage formation.

Animals↗
PubMed1998

Carbonates in fractures of Martian meteorite Allan Hills 84001: petrologic evidence for impact origin.

Carbonates in Martian meteorite Allan Hills 84001 occur as grains on pyroxene grain boundaries, in crushed zones, and as disks, veins, and irregularly shaped grains in healed pyroxene fractures. Some carbonate disks have tapered Mg-rich edges and are accompanied by smaller, thinner and relatively homogeneous, magnesite microdisks. Except for the microdisks, all types of carbonate grains show the same unique chemical zoning pattern on MgCO3-FeCO3-CaCO3 plots. This chemical characteristic and the close spatial association of diverse carbonate types show that all carbonates formed by a similar process. The heterogeneous distribution of carbonates in fractures, tapered shapes of some disks, and the localized occurrence of Mg-rich microdisks appear to be incompatible with growth from an externally derived CO2-rich fluid that changed in composition over time. These features suggest instead that the fractures were closed as carbonates grew from an internally derived fluid and that the microdisks formed from a residual Mg-rich fluid that was squeezed along fractures. Carbonate in pyroxene fractures is most abundant near grains of plagioclase glass that are located on pyroxene grain boundaries and commonly contain major or minor amounts of carbonate. We infer that carbonates in fractures formed from grain boundary carbonates associated with plagiociase that were melted by impact and dispersed into the surrounding fractured pyroxene. Carbonates in fractures, which include those studied by McKay et al. (1996), could not have formed at low temperatures and preserved mineralogical evidence for Martian organisms.

Calcium Carbonate↗
PubMed1980

Alzheimer's disease: X-ray spectrometric evidence of aluminum accumulation in neurofibrillary tangle-bearing neurons.

The elemental content of neurons of the hippocampus was studied by a combination of scanning electron microscopy and x-ray spectrometry in autopsy-derived brain tissue from three cases of senile dementia (Alzheimer type) and three nondemented elderly controls. Foci of aluminum were detected within the nuclear region of a high percentage of neurons containing neurofibrillary tangles from the cases of senile dementia as well as the elderly controls. The adjacent normal-appearing neurons from both groups of patients were virtually free of detectable aluminum. These findings suggest that the association of aluminum to Alzheimer's disease extends to the neuronal level.

Aluminum↗
PubMed1981

Binding of metals to cell envelopes of Escherichia coli K-12.

As representative of gram-negative bacteria, the isolated and purified envelopes of an Escherichia coli K-12 strain were used to determine metal-binding capacity. The envelopes were suspended in 5 mM metal solutions for 10 min and 23 degrees C, separated and washed by centrifugation, and analyzed for metal by either atomic absorption or X-ray fluorescence spectroscopy. Of 32 metals tested, large amounts (> 0.9 mumol/mg [dry weight]) of Hf and Os, intermediate amounts (0.1 to 0.4 mumol/mg [dry weight]) of Pb, Zn, Zr, Fe III, Mn, Mo, Mg, Co, and Ce IV, and small amounts (< 0.1 mumol/mg [dry weight]) of Na, K, Rb, Ca, Sr, Cu, Sc, La, Pr, Sm, U, Fe II, Ru, Ni, Hg, Pt, Pd, Au, and In were detected Li and V were not bound to the envelopes. Electron microscopy of unstained, thin-sectioned material provided an electron-scattering profile for localizing the bound metal within the envelope. Energy-dispersive X-ray analysis of thin sections detected all metals in single envelope vesicles. These data suggest that most metal deposition occurred at the polar head group regions of the constituent membranes or along the peptidoglycan layer. No leaching of envelope components was detected by monitoring radioactive probes within the lipopolysaccharide and peptidoglycan layers during metal uptake experiments, sodium dodecyl sulfate-polyacrylamide gel electrophoresis of proteins from metal-loaded envelopes, or protein and carbohydrate determinations on the wash fluids. These results suggest that membrane integrity was not disturbed under these ionic conditions.

Cell Membrane↗
PubMed1984

Varied light and scanning electron microscopic appearances of barium sulphate in smears and histological sections.

The various light and scanning electron microscopic appearances of barium sulphate in smears and in histopathological lesions in sections are illustrated. One type of barium sulphate (E-Z-HD) includes much larger, bright birefringent particles and has very different appearances from other widely used types. Such larger particles in sections were not originally suspected to be barium sulphate and were identified only by energy dispersive x ray analysis in a scanning electron microscope. This form of barium sulphate is used for double contrast upper gastrointestinal radiography, and is not thought to have been responsible for the lesions in which it has been observed by us.

Barium Sulfate↗