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PubMed2000

Use of a Technovit 7200 VLC to facilitate integrated determination of aluminum by light and electron microscopy.

Technovit 7200 VLC is an excellent embedding medium for both inorganic histochemistry by light microscopy and X-ray microanalysis by scanning and transmission electron microscopy. Liver samples from rats after intraperitoneal treatment with aluminum chloride were fixed in glutaraldehyde and embedded in the resin. Thick sections were easily cut on an ultramicrotome and stained with aluminon for aluminum (Al). An intense positive reaction with aluminon was observed in the Kupffer cells by light microscopy. The surface structures of the same resin block cut for light microscopy were observed under a scanning electron microscope fitted with an energy dispersive X-ray spectrometer. The Kupffer cells appeared white in the backscattered mode. Localization of Al in the Kupffer cells was confirmed by an X-ray distribution map in the scanning electron microscope. Subcellular localization of Al in the Kupffer cells was performed on the same semithin sections using a transmission electron microscope equipped with an energy dispersive X-ray spectrometer. Most Al was found in lysosomes of the Kupffer cells. The resin was stable in the electron beam and chlorine-free.

Acrylic Resins↗
PubMed2001

Observations at the articular surface of hip prostheses: an analytical electron microscopy study on wear and corrosion.

We used scanning electron microscopy in combination with X-ray microanalysis to evaluate Co-, Cr-, and Mo-based human femoral hip prostheses. In total, 23 retrieved implants and four new implants were included in this study. Scanning electron microscopy of the polished surface of all arthroplasties showed, in addition to the polishing marks, small round and angular holes or pits. Other types of surface irregularities were interpreted as wear or corrosion of the metal compound. In all cases studied, corrosion propagated from holes at the surface of the polished prosthesis heads, in some cases also along phase boundaries. X-ray microanalysis of the intact prosthetic surface showed a relative composition of the elements Co, Cr, and Mo, which was in agreement with the manufacturer's information (63:33:4%). However, X-ray microanalysis spot analysis of the surface holes showed deviation in the relative composition of the elements Co, Cr, and Mo and also the presence of Si, Ti, and Al. Furthermore, Ti and Al could be traced back at an artificially made fracture plane of a new prosthesis. Therefore, Ti and Al have to be present during the manufacturing process. These impurities in the metal prosthesis alloy may create a galvanic element with the Co, Cr, Mo alloy of the implant. If this is the case, such a galvanic element in combination with the electrolyte environment formed by body fluids, can induce galvanic corrosion with release of metal particles.

Arthroplasty, Replacement, Hip↗
PubMed2002

Calcium phosphate precipitation method for the treatment of dentin hypersensitivity.

PURPOSE: To evaluate the feasibility of the calcium phosphate precipitation (CPP) method as a treatment for dentin hypersensitivity using vital teeth of beagle dogs. Also, gingival tissue response to two types of CPP methods was examined histologically. MATERIALS AND METHODS: Dentin tubules of the dogs' vital teeth were exposed by shallow cavity preparation followed by etching with 50% citric acid to simulate the condition of hypersensitive dentin. After CPP treatment was applied to the vital tooth, the dentin surface and longitudinal sections were observed by SEM to evaluate the occluding ability of the CPP method. The precipitate was also analyzed by energy-dispersive X-ray microanalysis to obtain compositional information. The gingival tissue before and after CPP method was examined histologically with light microscopy. RESULTS: Dentin tubules were occluded homogeneously and completely with an apatitic mineral after application of the CPP treatment in vital teeth. However, the depth of the precipitate in dentin tubules from the dentin surface was approximately half that seen in extracted teeth. No histological change was observed in gingival tissues when NaHCO3 was used as a post-treatment solution of the CPP method, whereas another CPP method using NaOH solution resulted in atrophy and degeneration of the epithelium of gingival tissue.

Analysis of Variance↗
PubMed1992

Determination of exposure to cobalt and nickel in the atmosphere in the hard metal industry.

Cobalt and nickel, matrices of hard metal, have been shown to be respiratory sensitizers. Airborne dust at hard metal-grinding worksites in a factor with a work-force of about 180 grinders was analysed for cobalt and nickel. The electron-microscopic X-ray microanalysis of airborne dust particles demonstrated that they had the same metallic components as hard metal products. Andersen sampling revealed that 66% of total dust was respirable (< 7 microns). Consecutive personal sampling for individuals indicated log-normally distributed concentrations of total dust and cobalt. Of the workers surveyed, 12% (16 out of 133) were exposed to cobalt at more than 50 micrograms m-3, while 1.5% (two out of 133) were exposed to nickel concentrations of more than 50 micrograms m-3. A correlation between cobalt exposure concentrations and nickel concentrations for individuals was significant and positive. Further improvement of the working environment is necessary because of the hazard caused by exposure to cobalt and nickel.

Air Pollutants, Occupational↗
PubMed1995

[Morphological changes on gold-coated brass endodontic pins].

Scanning electron microscope (SEM) connected with X-ray microanalysis (EDX) was used to study surface alterations of gold-coated brass dental pins (Dentatus), taken out after some years from restored teeth due to necessity for repeating a restorative therapy. The study method led to establish that: --the gold coating of the base material, constituted of copper alloy, absolutely insufficient to prevent corrosion attack; --the observed morphological alterations are the consequence of a localized corrosion attack, produced by anaerobic bacteria, which origin is confirmed by the presence of S on the most attacked points; --finally the corrosive phenomenon does not cause a periapical pathology, but the process is contrary, or rather, it is the pathology that leads to the favourable conditions to create corrosion.

Copper↗
PubMed1990

Localization of pyroantimonate-precipitable calcium in the endolymphatic sac of the tree frog, Hyla arborea japonica.

The pyroantimonate technique and a new demineralization method were employed to visualize pyroantimonate-precipitable calcium in the endolymphatic sac of the tree frog. The precipitate was determined to contain calcium (Ca) by EGTA extraction and X-ray microanalysis. The precipitate was mainly localized around calcium carbonate (CaCO3) crystals when frogs were not loaded with calcium chloride (CaCl2). When crystalline growth was accelerated by loading with CaCl2, the precipitate increased in amount, especially around the crystals and in the basement membrane (lamina rara and reticular lamina). Various degrees of precipitation were found in epithelial cells; however, neither epithelial granules nor mitochondria seemed to have a significant amount of precipitate. This study demonstrates that Ca ion accumulates around those crystals where a dense material is located. The dense material probably has an affinity for the Ca ion, and plays an important role in crystal formation. However, the transport pathway for the Ca ion into the endolymphatic lumen is still obscure.

Animals↗
PubMed1984

Intracellular pathways of native iron in the maternal part of the porcine placenta.

In the diffuse epitheliochorial porcine placenta iron is secreted as uteroferrin by the maternal epithelium of the areola-gland subunit of the placenta. To elucidate the intracellular pathways of physiological iron in uterine gland epithelium material from 10 sows at 15 to 111 days of gestation was processed for electron microscopy by different routine methods with or without postfixation in osmium tetroxide. Ferritin particles were identified by their size and shape and the content of iron was confirmed by X-ray energy dispersive microanalysis of accumulated ferritin particles. Distinct ferritin particles were not observed in the extracellular space either basal to or luminal to the epithelial cells. Intracellular ferritin was observed apparently free in the cytoplasm, but in variable amounts. Transfer tubules and dense bodies were located basally in the secretory cells. Both of these organelles contained ferritin particles, showed reaction sites for acid phosphatase and were stained by periodic acid-thiocarbohydrazide-silver proteinate. The ciliated cells differed by having apically located dense bodies containing numerous ferritin particles. Our finding of native ferritin in cells with hormonally regulated iron transport supports the concept that transfer tubules as part of the lysosomal complex are part of the endocytic pathway in secretory cells and indicate that ferritin here is an intracellular transport or storage intermediate.

Animals↗
PubMed1986

Dissolution of stainless steel welding fumes in the rat lung: an x ray microanalytical study.

The dissolution of stainless steel welding fumes produced by manual metal arc (MMA) and metal inert gas (MIG) techniques was studied by transmission electron microscopy and quantitative x ray microanalysis in the lungs of rats after inhalation exposure. Rats exposed to stainless steel fumes generated by MMA were found to have two particle populations of different behaviour in their lung tissue. The particles of the principal population (size 100-250 nm) dissolved in both alveolar macrophages and type 1 epithelial cells in about two months. Fast and slowly dissolving components of chromium, manganese, and iron were detected within these particles; they obviously represent different chemical compounds. The particles of the minor population (size 5-100 nm) showed no signs of dissolution during three months follow up. Rats exposed to stainless steel fumes generated by MIG had only one particle population in their lung tissue; they were similar to those of the minor population in the MMA/SS fumes and no solubility could be detected within three months.

Animals↗
PubMed1992

Electron spectroscopic imaging and X-ray microanalysis of phosphorus in mouse sperm chromatin.

The influence of HCl hydrolysis on DNA detection in a Feulgen-type reaction using osmium ammine has been analyzed at the electron microscopic level by means of electron spectroscopic imaging, electron energy loss spectroscopy and X-ray microanalysis in energy dispersive spectroscopy. Both the stained DNA and the phosphorus mapping for a given hydrolysis condition were studied in parallel on the same nucleus. We have found that the pattern of osmium ammine-stained DNA and phosphorus imaging can be superimposed for a short hydrolysis time. After long HCl treatment, DNA is barely detectable by osmium ammine while phosphorus is still present in the thin sections. Taking into account the fact that the cells are embedded in a plastic resin, it is reasonable to think that in this case DNA depolymerization does not completely correspond to DNA loss. An incomplete loss of this highly denatured and depolymerized DNA from the plastic sections will explain both the presence of phosphorus and the poor stainability with a Schiff-type reagent.

Animals↗
PubMed1983

Schistosoma mansoni: the structure and elemental composition of pre-acetabular penetration gland cell secretion in pre-emergent cercariae.

The structure and elemental composition of the secretory products of the pre-acetabular penetration gland cells of pre-emergent cercariae of Schistosoma mansoni have been investigated at an ultrastructural level using X-ray probe microanalysis. The secretion contains 2 types of bodies, one homogeneous and one heterogeneous with electron-lucent areas. Using a variety of fixation and sectioning techniques it has been shown that the apparent electron density of the homogeneous bodies (Type B) is the result of interaction with osmium tetroxide and stain. The small electron-lucent areas of the other type of secretory body (Type A) represent regions where granules have been leached out by processing media. X-ray analysis of cercariae still within sporocysts has indicated that these granules are very rich in calcium, and it is suggested that the calcium is absorbed by the developing cercariae through the sporocyst wall from the molluscan haemolymph.

Animals↗
PubMed1989

[Structural, ultrastructural and microanalytical study of multiple enamel pearls].

Numerous enamel drops and compound enamel pearls were found on the radicular proximal faces of maxillary molars and mandibular third molars of a young woman. Enamel and dentin of compound pearls as well as cementum next to drops and pearls presented the same structure and ultrastructure as enamel, dentin and cementum of the corresponding teeth. Microanalysis did not reveal differences between enamel of the mother tooth and enamel of drops and pearls. The enamel drops had no incremental growth lines. Cementum next to enamel drops and compound enamel pearls was acellular and covered occasionally with a thick layer of cellular cementum. Only enamel drops were partially covered by acellular cementum. Close to the enamel drops and at their surface, numerous fusing globular calcifications were observed. Formation of enamel drops and compound enamel pearls on dental root surfaces is rare. The simultaneous presence of numerous enamel drops and some compound enamel pearls on several roots of molars in the same denture seems to be an exceptional phenomenon. The involved factors inducing enamel formation remain still unknown. The multitude of both enamel drops and compound enamel pearl might be due to constitutional predisposition.

Adult↗
PubMed1989

Dentine hypersensitivity. II. Effects produced by the uptake in vitro of toothpastes onto dentine.

Toothpastes arguably are the most common preparations used in the treatment of dentine hypersensitivity. Evidence for efficacy largely comes from clinical trials, and supports the role of the contained so-called "active" ingredient. How such compounds produce therapeutic benefit has received limited attention. This study measured the availability and uptake onto dentine of fluoride and metal ions contained in commercial and test toothpastes. The effects of exposure of dentine sections to these toothpastes, and abrasive only pastes in particular, was investigated by scanning electron microscopy and X-ray microanalysis. Aqueous extracts of the different toothpastes contained measurable concentrations of the incorporated metal and or fluoride, but usually considerably below that incorporated by the manufacturer. Extraction of dentine sections exposed to toothpaste slurries revealed levels of fluoride and metal ions, although post-treatment washing in water reduced these levels. Surface changes at 1 and 10 h were not consistent with the uptake of fluoride or metals. These changes were almost certainly produced by the contained abrasives, including calcium carbonate, dicalcium phosphate, alumina and silica. In particular fume silica progressively accumulated on the dentine surface to narrow and occlude dentinal tubules. Unlike other abrasives fume silica was resistant to removal by washing. It would appear that insufficient attention has been given to the therapeutic potential of toothpaste ingredients, particularly abrasives, to produce benefit by occlusion of dentinal tubules.

Dentifrices↗
PubMedDate not supplied

X-ray microanalysis of peripheral lung carcinomas.

A total of 15 cases of peripherally located lung carcinomas associated with scar (scar carcinoma) were studied by light microscopy and electron microscopy with energy-dispersive X-ray microanalysis (XMA). Results were compared to those of three autopsy lungs without significant pulmonary findings that served as controls. Fibrosis with scar formation characterized the 15 tumor cases. Particulate depositions including doubly refractile particles were also increased in the tumor group. XMA identified 25 elements with great complexity of particulate composition. Silicon was the most prominent element and was found in 16 of 18 cases studied. Kaolinite, feldspar, talc, muscovite, and silica were recognized. The fibrogenic properties of silicate compounds were emphasized, including their prominence in the lung tumor group. While the important concept of tumor desmoplasia was recognized, the study showed significant fibrosis in relation to fibrogenic materials, which undoubtedly preceded the appearance of the tumors. Also noted were the carcinogens uranium, cadmium, chromium, nickel, and arsenic, some of which were previously described as minor constituents of naturally occurring minerals.

Adenocarcinoma↗
PubMed2000

Surface characterization of retrieved NiTi orthodontic archwires.

The structure and morphological condition of retrieved NiTi orthodontic archwires was evaluated and any possible alterations in the surface composition of the alloy following 1-6 months in vivo were characterized. NiTi wires (GAC, German Orthodontics, ORMCO) of various cross-sections were collected through a retrieval protocol and were subjected to multi-technique characterization. Optical microscopy revealed islands of amorphous precipitants and accumulated microcrystalline particles. Micro MIR-FTIR investigation of the retrieved samples demonstrated the presence of a proteinaceous biofilm, the organic constituents of which were mainly amide, alcohol, and carbonate. Scanning electron microscope and X-ray microanalysis showed that the elemental species precipitated on the material surface were Na, K, Cl, Ca, and P, forming NaCl, KCl, and Ca-P precipitates. Increased intra-oral exposure was consistently associated with the presence of a mature film, while evidence of alloy delamination, pitting, and crevice corrosion, as well as a notable reduction in the alloy grain size was observed. Intra-oral exposure of NiTi wires alters the topography and structure of the alloy surface through surface attack in the form of pitting or crevice corrosion or formation of integuments. Further in vivo research is required to resolve the implications of the described ageing pattern in the corrosion resistance of the alloy, the potential for nickel leaching, as well as bracket-archwire friction variants.

Alcohols↗
PubMed1984

Calcium distribution in freeze-dried enamel organ tissue during normal and altered enamel mineralization.

Energy dispersive X-ray microanalysis was applied to freeze-dried blocks of enamel organ tissue to determine levels of calcium in various cellular regions. The tissue blocks were dissected free from adjacent forming enamel following injection of cobalt or fluoride ions, both of which temporarily inhibit enamel mineralization. In all control and experimental specimens there was an increasing gradient of calcium from the stratum intermedium cells to the distal ends of the ameloblasts. Calcium levels were significantly reduced near the distal ends of the ameloblasts following cobalt or fluoride injection as compared with controls. It is suggested that evidence of an intercellular buildup of calcium near the distal ends of the ameloblast supports a controlling function of these cells. The changes in calcium levels are correlated with alterations in mineralization known to occur in the adjacent enamel of the model systems employed.

Ameloblasts↗
PubMed1994

Heterogeneity in ultrastructure and elemental composition of perinuclear lens retrodots.

PURPOSE: To unravel the cataractogenic process(es) leading to the birefringent lenticular bodies known as perinuclear retrodots. METHODS: Ten human lenses containing biomicroscopically verified perinuclear retrodots were systematically screened and analyzed using scanning electron microscopy and energy dispersive x-ray microanalysis to verify their ultrastructure and elemental composition. RESULTS: Three types of retrodots were distinguished, different in size, ultrastructure, and origin. Two of them contained calcium phosphate, the third probably contained calcium oxalate. All three types were separated from surrounding normal fibers and the crystalline inclusions were sequestered within membrane-lined bodies. CONCLUSIONS: Because of these observations and data found in the literature it is postulated that elevated free calcium is the initiating factor in the formation of retrodots, trapped by either oxalate or phosphate and sequestered in the retrodots. It is suggested that the oxalate is derived from ascorbate because of impaired protection against oxidative stress in the older lens. Phosphoric acid is believed to be released by calcium-induced hydrolysis of membrane phospholipids.

Calcium Oxalate↗
PubMed1992

The ultrastructure of the bone-hydroxyapatite interface in vitro.

Rat bone marrow cells were cultured on plasma-sprayed hydroxyapatite (HA). The cells formed a mineralized extracellular matrix (ECM) that exhibited several characteristics of bone tissue. The interface between this mineralized ECM and the HA was studied at the ultrastructural level with scanning and transmission electron microscopy and x-ray microanalysis. Initially, the deposition of a globular, afibrillar matrix was observed on HA. This was followed by the integration of collagen fibers in this matrix and their subsequent mineralization. At the bone-HA interface two distinctly different interfacial structures were observed. An electron-dense layer with a thickness of 20-60 nm was regularly present, which contained both organic and inorganic material and was rich in glycosaminoglycans. The interfaces differed however, in the presence or absence of an amorphous zone which was free of collagen fibers and had an average thickness of 0.7-0.8 microns. It was frequently seen interposed between the electron-dense layer and the hydroxyapatite. Similar interfacial structures have also been described in the in vivo environment, where they were referred to as lamina limitans-like or cement linelike. From the results of this study, it can be concluded that the described in vitro system is a suitable model to study bone-biomaterial interactions.

Animals↗
PubMed1984

[Changes in the muscle ultrastructure and electrolyte composition of rats in embryogenesis. II. X-ray spectrum microanalysis of the intracellular concentrations of potassium, sodium and phosphorus in skeletal and heart muscle].

Concentrations of K, P and Na were determined in skeletal and cardiac muscle cells of rat embryos. High K and P levels--133 and 166 mmole/kg wet weight, resp.,--were found in skeletal muscles of 13 day old embryos, the concentration of Na in these cells being 81 mmole/kg w. w. On the 18th day of development, K and P in skeletal muscle cells decreased down to 79 and 118 mmole/kg w. w., resp., while the concentration of Na increased to 165 mmole/kg w. w. In 19 day old embryos, the concentrations of K and P increased, although they did not reach the level typical of skeletal muscles of adult rats. The concentrations of K and P in cardiac muscle cells of 13 day embryos were found equal to 100 and 108 mmole/kg w. w., resp., on the 19th day of development these concentrations reached the level typical of the cardiac muscle cells of adult rats.

Animals↗