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Results for “Electron Probe Microanalysis”

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PubMed1981

Occupational argyria; light and electron microscopic studies and X-ray microanalysis.

Microscopic studies have been performed on skin biopsies from five patients with occupational argyria. Small brown-black granules were present in the dermis on light microscopy and were intensely refractile with dark-field illumination. Electron microscopy showed that the granules were electron-dense, round or oval in shape and varied in size from 30 nm to 100 nm. They were most numerous in relation to the basal lamina of the eccrine sweat glands, but were also present in relation to the basal lamina of the epidermis and dermal elastic fibres. X-ray microanalysis confirmed that many of the granules contained silver and sulphur. However, selenium, mercury, titanium and iron were also identified and it is probable that these elements were deposited in the skin also as a result of occupational exposure.

Adult↗
PubMed1982

Microanalysis of the reaction product in Karnovsky and Roots histochemical localization of acetylcholinesterase.

X-ray energy dispersive microanalysis of the reaction product in Karnovsky and Roots histochemical localization of acetylcholinesterase indicated the presence of sulfur, iodine, copper, and iron. The reaction was run in vitro using purified acetylcholinesterase from the electric eel to confirm our previous results on similarly treated neuromuscular junction in situ.

Acetylcholinesterase↗
PubMed2006

Hepatocyte nuclear structure and subcellular distribution of copper in zebrafish Brachydanio rerio and roach Rutilus rutilus (Teleostei, Cyprinidae) exposed to copper sulphate.

Copper is a trace element essential to life, but also a heavy metal with toxic effect clearly demonstrated. Cu induced perturbations in fish liver are well documented but the variability of the reported results is large. In this study two cyprinids, zebrafish and roach, were exposed to copper. Reported histocytological changes are either adaptative or degenerative depending on fish species, concentration of metal, and duration of exposure. Hepatic subcellular distribution of copper was determined by X-ray microanalysis in control and Cu-exposed roach and zebrafish. Sublethal copper sulphate contamination induced the development of a particular nucleolar alteration forming a network or honeycomb like structure in liver. This perturbation is observable in almost all the hepatocytes of zebrafish and roach exposed to copper for a minimum of 4 days of exposure. It seemed to concern more precisely the pars fibrosa. X-ray microanalysis showed that the appearance of network nucleolus was in relation to a Cu accumulation. Cu deposit was well located in the network as pars granulosa and nucloplasm showed very lower metal concentrations. The origin and consequence of network structure in nucleolus was discussed.

Animals↗
PubMed1999

[The fine fraction of airborne particulate: a pollutant of increasing environmental and health relevance. Methodologies for sampling and characterizing single particles].

Among the atmospheric pollutants detectable in the environment, the inhalable airborne particulate (PM10) is regarded with increasing care. Indeed a number of epidemiological studies support the correlation between both acute and chronic adverse health effects and the PM10 pollution in the urban environment. According to recent results the health effects could be related to the physico-chemical characteristics of the particulate itself. With the aim of characterising the individual particles, PM10 samples collected by multi-stage cascade impactor are examined by scanning electron microscopy (SEM) and X-ray microanalysis with energy dispersion spectroscopy (EDS). The obtained data are analysed using multivariate statistical techniques (hierarchical clustering methods, principal factor analysis) to determine the components of the particulate. By these methods a series of studies was carried out by the Istituto Superiore di Sanità to investigate the PM10 pollution in several environmental situations.

Air Pollutants↗
PubMed2005

Localization of specific monosaccharides in cells of the brown alga Padina gymnospora and the relation to heavy-metal accumulation.

The brown alga Padina gymnospora has been studied due to their ecological significance and biochemical characteristics, including its high capability of heavy-metal accumulation. It has been suggested that the fucans are among the main polysaccharides related to metal binding and precipitation in cell walls. The main purpose of this work was to determine the localization of specific monosaccharides in P. gymnospora cells. In this way, the lectins Ulex europaeus agglutinin and Canavalia ensiformis concanavalin A with specificity to alpha-L-fucose and to terminal residues of alpha-D-glucosyl and alpha-D-mannosyl, respectively, were applied in young individuals. These revealed a preferential distribution of alpha-L-fucose at cell walls near the external surface in cortical cells and near the plasmalemma in cortical and medullar cells. The distribution of alpha-L-fucose in cell walls indicates the distribution of sulfated polysaccharides (sulfated fucans) that colocalize with the heavy-metal granules (Zn and Cd) described in previous works. Therefore, our results suggest that alpha-L-fucose participates in the nucleation and immobilization of heavy metals in P. gymnospora cell walls. An intense labeling of U. europaeus agglutinin and a weak labeling of concanavalin A was also observed in physodes. X-ray microanalysis revealed the presence of zinc, sulfur, and calcium in physodes of algae collected in a heavy-metal-contaminated area. Besides the affinity between polyphenolic compounds and heavy metals, it is suggested that the mechanism of metal binding by physodes could be related to the presence of sulfated fucans.

Cell Wall↗
PubMed2004

Pulmonary fibre burden in sheep living in the Biancavilla area (Sicily): preliminary results.

In a national survey on mortality from malignant pleural neoplasms in Italy, aimed at detecting geographic clusters of cases of the disease, the town of Biancavilla, located in a volcanic area of Eastern Sicily, showed high risk of pleural mesothelioma in the absence of occupational asbestos exposure. An environmental survey suggested the stone quarries located in 'Monte Calvario', south-east of the town of Biancavilla, as a possible source of asbestiform fibre exposure. A subsequent crystal-chemistry investigation of the 'Monte Calvario' amphiboles identified the mineral asbestiform fibres as 'fluoro-edenite', a new end-member of the edenite ==> fluoro-edenite series. A collaborative epidemiological and environmental study was initiated to investigate the characteristics of the outbreak of malignant mesothelioma and test the hypothesis of a causal association with exposure to naturally occurring fibres. To investigate if a sheep population could be used to monitor the environmental diffusion of the fibres, we examined lung specimens from 27 culled sheep, at least 3 years old and living near Monte Calvario to check for the presence of fluoro-edenite fibres, using scanning electron microscopy (SEM) analysis and X-ray microanalysis. Fourteen mineral species have been isolated in the mineral particulate matter taken from pulmonary parenchyma, and fluoro-edenite was detected in eight sheep. These preliminary data suggest a possible bio-indicative role of sheep as sentinel animals in the evaluation of environmental fibre diffusion, which merits further investigation.

Animals↗
PubMed1998

Blood vessels and red blood cells preserved in dinosaur bones.

Dinosaur bones, 80 million years old, were studied in the scanning electron microscope, and subjected to X-ray microanalysis. Samples for the investigations were prepared according to specially elaborated, and simultaneously described methods. Analysed were (a) the morphological structure of the blood vessels and (b) the remains of their contents. The walls of the blood vessels were found to be morphologically identical with those in present-day reptiles. Bodies were found at several places inside the vessels which strongly remind one of erythrocytes in modern bones. X-ray microanalysis of places where these bodies were accumulated revealed much higher levels of iron, than at any other regions of the blood-vessel wall. Further analysis of the "dinosaur erythrocyte" iron content could be a starting point for the possible determination of oxygen in the earth's atmosphere, 80 million years ago.

Animals↗
PubMed2001

Contribution of cryofixation and freeze-substitution to analytical microscopy: a study of Tritrichomonas foetus hydrogenosomes.

The hydrogenosome, an organelle that produces molecular hydrogen and ATP from the oxidation of pyruvate or malate under anaerobic conditions, presents some characteristics common to mitochondria. It is found in several trichomonad species, protists living in oxygen-poor environments, as well as certain free-living ciliates, rumen ciliates, and some fungi. We performed a comparative microanalytical study (energy dispersive X-ray analysis and electron spectroscopic imaging) of different fixation methods for electron microscopy analyzing hydrogenosomes of the bovine parasite Tritrichomonas foetus. The study included the elemental composition and the mapping of calcium, phosphorus, and oxygen. A preparation of T. foetus cells, based on cryoimmobilization by high-pressure freezing and freeze-substitution, was compared to a second preparation based on chemical fixation followed by dehydration and routine processing. The ultrastructural preservation achieved by the cryotechnique was far superior to the chemical fixation, since it allowed the successful cryoimmobilization of intracellular ion contents. The detection of several cations (Al, Mg, Co, Ca, Fe) by X-ray microanalysis inside the peripheral vesicle of the hydrogenosome was only possible in cryofixed cells. The presence of aluminum and cobalt ion in the hydrogenosomal vesicle was established for the first time. Electron-spectroscopic images of calcium showed that this element, in addition to the vesicle compartment, is present in the hydrogenosome's membrane in varying concentrations, which might reflect changes in the physiology of this organelle.

Animals↗
PubMed2000

Alumina powder/Bis-GMA composite: effect of filler content on mechanical properties and osteoconductivity.

Three composites consisting of alumina powder dispersed in a bisphenol-a-glycidyl methacrylate (Bis-GMA) matrix were prepared and evaluated to assess the effect of alumina powder content on the mechanical properties and osteoconductivity of the composite. The alumina powder composites (APC) consisted of alumina powder (AL-P) as the inorganic filler dispersed in a Bis-GMA matrix that was solidified by a radical polymerization process. Prior to polymerization the AL-P was mixed with the monomers in proportions of 50%, 70%, and 80% by weight (APC50, APC70, and APC80). A fused silica-glass-filled composite containing 70% glass by weight (SGC70) was used as a control. The compressive and bending strengths, the elastic modulus in bending, and the bending strain of the composites increased as the AL-P content increased. We also evaluated the composites in vivo by implanting them into the medullary canals of rat tibiae. To compare the osteoconductivity of the composites, an affinity index was calculated for each composite; the affinity index equals the length of a bone in direct apposition to the composite and is expressed as a percentage of the total length of the composite surface. Microradiographic examination for periods of up to 26 weeks after implantation revealed that APC50, APC70, and APC80 all exhibited excellent osteoconductivity and made direct contact with the bone with no interposed soft tissues. However, the higher the AL-P content of the composite, the higher the osteoconductivity, especially at 4 weeks after the operation. Moreover, the amount of bone directly apposed to the composite surface increased with time. In contrast, little bone formation was seen on the surface of SGC70, even after 26 weeks. Observation by scanning electron microscope-energy dispersive X-ray microanalysis demonstrated that bone made direct contact with the APC surface through a layer containing calcium, phosphorus, and alumina powder. These results suggest that APC shows promise as a basis for developing mechanically strong and highly osteoconductive composites.

Aluminum Oxide↗
PubMed1984

Clinical applications of scanning electron microscopy and X-ray microanalysis in dermatology.

Scanning electron microscopy is frequently applied to dermatological problems, as is evident from a review of the recent literature. In this tutorial, preparation methods and new techniques allowing experimental studies on the integumentary system are emphasized. Quantitative analysis in the electron microscope by use of energy-dispersive X-ray microanalysis ( EDX ) has become an important accessory technique. EDX can, for instance, be used to study problems involving physiological changes induced in skin by agents causing contact reactions. Recently, it has been shown that treatment with DNCB, chromate and nickel causes changes in elemental distribution in guinea-pig skin. In addition, elemental uptake in the integumentary system and in pathological inclusions in skin can be analyzed.

Animals↗
PubMed2004

Hemocyte-mediated shell mineralization in the eastern oyster.

The growth of molluscan shell crystals is usually thought to be initiated from solution by extracellular organic matrix. We report a class of granulocytic hemocytes that may be directly involved in shell crystal production for oysters. On the basis of scanning electron microscopy (SEM) and x-ray microanalysis, these granulocytes contain calcium carbonate crystals, and they increase in abundance relative to other hemocytes following experimentally induced shell regeneration. Hemocytes are observed at the mineralization front using vital fluorescent staining and SEM. Some cells are observed releasing crystals that are subsequently remodeled, thereby at least augmenting matrix-mediated crystal-forming processes in this system.

Animals↗
PubMed1984

Rheumatoid pneumoconiosis in a dolomite worker: a light and electron microscopic, and X-ray microanalytical study.

A 46-year-old woman suffering from rheumatoid arthritis developed numerous round opacities at the apex of the right lung 11 years after an exposure to dolomite . Resected lung showed discrete nodules, 0.8-2 cm in diameter, with central necrosis surrounded by palisading fibroblasts and a prominent inflammatory zone. A large number of birefringent dust particles were seen in the necrotic centres and around the nodules. By electron microscopy the particles were dense, mostly elongated and lamellar, varying from 0.005 to 3 microns in width, and from 0.1 to 6.5 microns in length. Energy dispersive x-ray microanalysis of the dust particles gave elemental spectra with high spikes of silicon, aluminium and potassium, and minimal magnesium, calcium, iron and titanium. According to chemical analysis, the original dolomite consisted almost entirely of magnesium and calcium carbonates and only of traces of silicon, aluminium and potassium. Apparently the human organism can better eliminate calcium and magnesium carbonates than silicon, aluminium and potassium.

Calcium Carbonate↗
PubMed1986

Is mucus involved in biocrystallization? Study of the intestinal mucus of the sea-water eel Anguilla anguilla L.

Freeze-dried intestinal mucus of sea-water-adapted eels was analysed by scanning electron microscopy (SEM) and X-ray microanalysis. Calcite crystals were observed in the mucus fibres; their concentration increased along the hindgut. Random SEM observations made in situ indicated that mucus fibres were involved in the genesis of these crystals. Calcium-rich mucus globules were found fused inside crystal matrices. Single typical rhombohedric crystals of various complexity appeared within the mucus framework. The steps of crystal biogenesis were reconstituted in in-vitro conditions.

Anguilla↗
PubMed1987

[Structure, ultrastructure and microanalysis of the enamel of teeth near maxillary clefts].

Teeth located in the vicinity of cleft palate were studied using correlated light microscopy, microradiography, SEM, TEM and microanalysis. Structural, ultrastructural and chemical abnormalities were found in enamel. The enamel surface presented micro and gross hypoplasia, associated with hypomineralization. Microradiography showed the antenatal enamel to be more mineralized than postnatal enamel. Microanalysis showed the Ca/P ratio measured at the enamel surface to be higher in the teeth associated with cleft palate, compared with controls. The Ca/P value was due to a Ca increase and a P decrease in the enamel surface. The Ca increase was correlated with a decrease in Mg, supporting the hypothesis of a Mg/Ca substitution in the apatitic structure.

Adolescent↗