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PubMed1992

[Pulmonary fibrosis after inhalation of amorphous silicic acid].

Light- and scanning electron microscopical studies with energy dispersive x-ray microanalysis were performed on biopsy material obtained from two patients with longstanding occupational exposure to amorphous silica, in whom radiologically interstitial pulmonary fibrosis in vicinity of dust deposits, which could be identified as amorphous and rarely as crystalline silica, was found. The direct topographical relationship between the dust deposits and the tissue reaction indicate that the amorphous silica incorporated in the fibrotic foci is responsible for the development of the fibrosis.

Adult↗

PubMed1980

Scanning electron microscopy and x-ray microanalysis of mineral deposits in lungs of a patient with pleural mesothelioma.

Scanning electron microscopy of lung tissue, ashed at low temperature, and obtained from an insulation worker who had died of pleural mesothelioma, showed the presence of numerous inorganic particles and fibres. A regional variation in fibre concentration in different tissue samples was found, and the size distribution of naked fibres and asbestos bodies was determined. By energy dispersive x-ray microanalysis the fibres were identified mainly as amphibole asbestos. This method also showed the presence of particles containing titanium and of fragments of diatom shells. Despite a mean concentration of 33 x 10(6) fibres per gram of dry tissue no significant lung fibrosis was found.

Adult↗

PubMed1990

Analysis of glass ionomer cement with use of scanning electron microscopy.

In the study, scanning electronmicroscopy and x-ray microanalysis techniques were used to examine a silver-reinforced glass ionomer cement. Scanning electron microscopy was used to evaluate surface topography and microstructure. Microcracking and a bimodal pore distribution were observed. The cement consisted of unreacted glass particles surrounded by a silica gel "halo" and embeded in an organic salt matrix. Back-scattered electron microscopy and energy-dispersive spectroscopy detected discrete clusters of silver atoms within the material. Other elements, such as calcium and aluminum, were dispersed homogeneously. Wave-length dispersive spectroscopy was used to detect fluoride, which also appeared to be homogeneously distributed. Electron microscopy and x-ray microanalysis techniques could prove valuable in clarifying the microstructure and fluoride release mechanisms of glass ionomer cements. Refinement of some aspects, including sample preparation, will be necessary to obtain consistently reliable results.

Aluminum↗

PubMed1987

Morphology of the osteonal cement line in human bone.

While current consensus suggests the absence of collagen in osteonal cement lines, the extent of cement line mineralization and the nature of the ground substance within the cement line are unclear. Samples of human radius were examined by using scanning electron microscopy, electron microprobe, and histochemical techniques. X-ray intensities were used to compare the amount of calcium, phosphorus, and sulfur in cement lines with amounts in surrounding lamellar bone. The results indicate that cement lines contain significantly less calcium and phosphorus, but significantly more sulfur, than surrounding bone matrix. The Ca/P ratio of cement lines was significantly greater than that of lamellar bone, suggesting that the mineral in cement lines may not be in the form of mature hydroxyapatite. No selective staining of the cement lines could be demonstrated by using periodic acid-Schiff, Sudan black B, or alcian blue critical electrolyte concentration techniques.

Adult↗

PubMed1992

Effects of the Nd:YAG dental laser on plasma-sprayed and hydroxyapatite-coated titanium dental implants: surface alteration and attempted sterilization.

The Nd:YAG dental laser has been recommended for a number of applications, including the decontamination or sterilization of surfaces of dental implants that are diseased or failing. The effects of laser irradiation in vitro (1) on the surface properties of plasma-sprayed titanium and plasma-sprayed hydroxyapatite-coated titanium dental implants, and (2) on the potential to sterilize those surfaces after contamination with spores of Bacillus subtilis have been examined. Surface effects were examined by scanning electron microscopy, energy dispersive spectroscopy, and x-ray diffraction after laser irradiation at 0.3, 2.0, and 3.0 W using either contact or noncontact handpieces. Controls received no laser irradiation. Melting, loss of porosity, and other surface alterations were observed on both types of implants, even with the lowest power setting. For the sterilization study, both types of implants were first sterilized by exposure to ethylene oxide and then contaminated with spores of B subtilis. After laser irradiation, the implants were transferred to sterile growth medium and incubated. Laser irradiation did not sterilize either type of implant. The spore-contaminated implants in the control group were successfully sterilized with ethylene oxide.

Bacillus subtilis↗

PubMed1981

Comparative light microscopical and X-ray microanalysis study of barium granuloma.

A barium granuloma occurring in the gastric wall was examined by various light microscopical methods and with the scanning electron microscope in association with an energy dispersive x-ray spectrometer. Barium sulphate is present in the form of a slightly granular, yellowish and greenish substance within the cytoplasm of macrophages, and shows no birefringence. Needle-shaped and rhomboid birefringent crystals are rich in magnesium and silicon, and most probably present talc crystals, one of the admixtures in common commercial preparations used for contrast x-ray examination of the gastrointestinal tract, rather than crystals of barium sulphate proper as erroneously interpreted in the literature.

Barium↗

PubMed1978

Quantitative X-ray microanalysis of diffusible ions in the skeletal muscle bulk specimen.

X-ray microanalysis in the scanning electron microscope (SEM) is used to obtain information about the distribution and mobility of electrolyte ions in the skeletal muscle tissue. In order to localize the diffusible ions in their physiological state, so far as possible, any chemical fixative is avoided. A special 'cooling chain' preparation method is applied which enables studies on cryofractured bulk specimens at low temperatures. Quantitation of the obtained X-ray spectra is done by the use of glycerol-treated tissue specimens which are incubated with electrolyte solutions of defined ion concentration.

Animals↗

PubMed1988

The X-ray microanalysis method for investigation of chemical composition of normal and pathologic human peripheral blood lymphocytes.

The X-ray microanalysis method for investigation of chemical composition, mainly trace elements, of normal and pathologic human peripheral blood lymphocytes has been presented. The method in question consists of two stages. During the first stage the scanning electron microscope with the energy dispersive X-ray spectrometer has been used. The second stage of the method consisted of employing the above microscope with the microwave dispersive spectrometer. The method enables the short-term determination of the various elements content within the lymphocytes with particular insight into the content of elements in a single cell. The preliminary investigations showed significant differences in the content of chlorine, sulfur and lead in normal human lymphocytes and that from patients with cancer of the larynx.

Carcinoma, Squamous Cell↗

PubMed1995

Material and compositional properties of selectively demineralized cortical bone.

Timed immersion in buffered ethylenediamine-tetraacetic acid (EDTA) was used to selectively alter the mineral content at each level in the cortical bone structural hierarchy. The effects on the mechanical behavior were investigated using a combination of experimental techniques which provide collectively a wide range of resolution (5 microns to 3 mm). Optical microscopy and histological analysis demonstrated a heterogeneous structure consisting of a mineralized tissue core surrounded by a layer of demineralized tissue (collagen) whose thickness varied depending on the immersion time. The mechanical behaviors of treated samples with (intact) and without (core) the surrounding demineralized layer were evaluated using three-point flexure. Overall, the intact specimens became significantly less brittle with increased immersion time in buffered-EDTA. For the core specimens, there was a systematic decrease in the elastic flexural properties (E, sigma e, epsilon e). The site-specific properties of the specimens were determined using microhardness testing, scanning acoustic microscopy, and wavelength dispersive analysis. The mineralization and site-specific properties of the mineralized cores were not significantly affected by buffered-EDTA immersion; however, histomorphometric analysis showed a decrease in the mineralized volume fraction via widening of the pre-existing vascular channels. The experimental hierarchy was effective in discerning site-specific property changes and the localized heterogeneities resulting from the buffered-EDTA treatment. Based on the results of this study, buffered-EDTA treatment can be used to facilitate the determination of material and physical properties of intact and demineralized tissues within a single cortical bone sample.

Animals↗

PubMed1989

Microscopic examination of embrittled pin-retained base metal casting.

Differential thermal analysis, optical microscopy, scanning electron microscopy, and energy dispersive radiographic analysis were used to examine and analyze two failed platinum-palladium-gold pin-retained nickel-chromium castings. The microstructure and chemical composition of the pin-casting interface were different from those of the pin and the cast alloy. Porosity was also observed at the interface. The observations with these samples suggest that the pin melted during casting. The embrittlement and failure of plantium-palladium-gold pins cast with nickel-chromium alloy have been attributed to this melting phenomenon. Further study is necessary to determine whether these observations are valid for a large number of samples.

Chemical Phenomena↗

PubMed1977

Electron probe x-ray microanalysis of frozen-hydrated biological specimens.

A technique is described for preparing frozen-hydrated bulk samples of biological specimens for electron probe X-ray microanalysis. The method allows reproducible quantitative analyses to be made. Specimens are rapidly frozen, transferred to a vacuum evaporator, fractured under high vacuum at - 180 degrees C and coated with 20 nm of chromium. Transferal to the cryostage of a scanning electron microscope is accomplished without exposure to the atmosphere and without the specimen temperature rising above -120 degrees C. Analyses are made at a temperature of -145 degrees C. Contamination by frost does not occur. Etching and charging of the specimen are eliminated. Specimen charging is shown to be related to temperature. It can be eliminated at low temperature by coating with carbon, aluminium or chromium but consistent elimination could only be achieved with chromium. The chromium coat does not appear to have an absorption effect on quantitative analysis.

Animals↗

PubMed1991

Crystalluria in marathon runners. III. Stone-forming subjects.

In order to investigate further the possible relationship between urinary stone formation and marathon running, the crystalluria in seven male, stone forming runners was characterized. Particle size distribution curves (Coulter counter) and crystal number, size and morphology (scanning electron microscopy) were measured. These studies suggest that urinary stone formation may be accelerated in those subjects with previous histories of renal stone formation but that the nature of the crystalluria is favourably affected by an increase in fluid intake. The presence of large quantities of mucoid material in the urine of "natural" stone formers and its absence in the urine of stone-forming runners is cited as evidence for the existence of different aetiological mechanisms in these groups. It is concluded that while natural stone formers may be at chronic risk of stone formation due to pathological factors, marathon runners may be at acute risk due to factors associated with long distance running itself.

Adult↗

PubMed1999

Cell surface and substrate distribution of the 67-kDa laminin-binding protein determined by using a ligand photoaffinity probe.

BACKGROUND: Peptide 11, a nine-amino acid sequence from the beta1 chain of laminin-1, has been reported to inhibit tumor cell invasion of basement membranes, and to reduce tumor lung colonization (Iwamoto et al.: Science 238:1132-1134, 1987; Landowski et al.: Clin Exp Metastasis 13:357-372, 1995). The peptide is a ligand for the 32/67-kDa laminin-binding protein (LBP); however, the mechanism by which the 67-kDa LBP promotes invasion is unknown. METHODS: We have synthesized a highly specific probe for the 67-kDa LBP by adding a biotinylated residue, and replacing the required tyrosine in peptide 11 with the photoactivatable bezophenone crosslinker, 4-benzoyl-L-phenylalanine. This probe was used to follow the distribution of the 67-kDa LBP by gel electrophoresis, fluorescence-activated cell scanning, and confocal microscopy techniques. RESULTS: A single crosslinked protein, consistent with the high molecular weight form of the LBP, was found on Western blots of membrane detergent extracts from cells treated with the ligand probe. A CHO cell line, manipulated to overexpress the laminin-specific alpha6beta1 integrin, exhibited increased invasiveness, and expressed more cell surface 67-kDa LBP. Membrane-associated 67-kDa LBP was found in the vicinity of focal adhesion plaques and also associated with the matrix substrate. Studies on conditioned medium indicated that the matrix-associated LBP derived from material that was shed from the cells, with more being shed from the more invasive CHO variants. CONCLUSIONS: These results demonstrate the utility of this novel probe in diverse experimental protocols, and suggest that shedding of the 67-kDa LBP may have a role in promoting tumor cell invasion.

Animals↗

PubMed2001

Bioactive glass stimulates in vitro osteoblast differentiation and creates a favorable template for bone tissue formation.

In this study, we have investigated the behavior of fetal rat osteoblasts cultured on bioactive glasses with 55 wt% silica content (55S) and on a bioinert glass (60S) used either in the form of granules or in the form of disks. In the presence of Bioglass granules (55 wt% silica content), phase contrast microscopy permitted step-by-step visualization of the formation of bone nodules in contact with the particles. Ultrastructural observations of undecalcified sections revealed the presence of an electron-dense layer composed of needle-shaped crystals at the periphery of the material that seemed to act as a nucleating surface for biological crystals. Furthermore, energy dispersive X-ray (EDX) analysis and electron diffraction patterns showed that this interface contains calcium (Ca) and phosphorus (P) and was highly crystalline. When rat bone cells were cultured on 55S disks, scanning electron microscopic (SEM) observations revealed that cells attached, spread to all substrata, and formed multilayered nodular structures by day 10 in culture. Furthermore, cytoenzymatic localization of alkaline phosphatase (ALP) and immunolabeling with bone sialoprotein antibody revealed a positive staining for the bone nodules formed in cultures on 55S. In addition, the specific activity of ALP determined biochemically was significantly higher in 55S cultures than in the controls. SEM observations of the material surfaces after scraping off the cell layers showed that mineralized bone nodules remained attached on 55S surfaces but not on 60S. X-ray microanalysis indicated the presence of Ca and P in this bone tissue. The 55S/bone interfaces also were analyzed on transverse sections. The interfacial analysis showed a firm bone bonding to the 55S surface through an intervening apatite layer, confirmed by the X-ray mappings. All these results indicate the importance of the surface composition in supporting differentiation of osteogenic cells and the subsequent apposition of bone matrix allowing a strong bond of the bioactive materials to bone.

Animals↗

PubMed1991

The effect of lead acetate on dentine formation in the rat.

The intravenous injection of lead acetate produces a response in dentine by formation of the so-called lead line. This is associated with a rapid but temporary rise in serum calcium and phosphorus. Previous studies have suggested that lead replaces calcium and phosphorus in the apatite lattice. In this study the lead line was investigated in the scanning electron microscope using backscattered electron imaging and was shown to consist of continuous hypomineralized interglobular spaces within the dentine. Dentine formation was disrupted for at least a week after injection of lead ions. With energy dispersive analysis by X-rays, no localized concentration of lead was detectable within the 'lead line'. It is suggested that the lead line results from a direct effect of lead on the odontoblasts and other hard tissue-forming cells producing a rapid loss of intracellular calcium temporarily displaced by lead ions and a subsequent disturbance of local calcium metabolism.

Animals↗

PubMed1996

Subcellular distribution of protein kinase C in the living outer hair cell of the guinea pig cochlea.

Immunohistochemical staining using isoform-specific antibodies and intracellular localization using fluorescent probes for protein kinase C (PKC) were evaluated in the cochlear outer hair cell (OHC). Among three isoforms of classic PKC, PKC alpha was selectively stained in the fixed OHC as well as inner hair cells under a surface preparation method. Two types of fluorescent probes to detect subcellular localization of PKC were observed with a confocal laser scanning microscopy in the present study, fim-1 diacetate which binds to the ATP-competitive catalytic domain of PKC and Bodipy FL C12-phorbol acetate which binds to specific site localized to the first cysteine-rich loop of the C1 region in the regulatory domain. High fluorescence intensity of both dyes was observed in subcuticular and subsynaptic regions, infracuticular network, and along the lateral wall. The displacement experiments to evaluate binding specificity were performed by incubating Bodipy FL C12-phorbol acetate in the presence of 10 microM phorbol 12-myritate 13-acetate (PMA) and the fluorescence was totally disappeared. For the acute treatment of phorbol ester, cells were preincubated with 1 microM PMA 30 min before loading with fim-1 diacetate. The brightest area in the plasma membrane became much larger as compared with untreated cells, which suggests a dramatic translocation of PKC to the plasma membrane. The biological functions involving PKC in the OHC are discussed.

Adenosine Triphosphate↗

PubMed1998

Fusion of Sendai virus and individual host cells and inhibition of fusion by lipophosphoglycan measured with image correlation spectroscopy.

Fusion between Sendai virus (SV) and individual host cells was investigated with confocal laser scanning microscopy (CLSM) and image correlation spectroscopy (ICS). SV was labeled with the fluorescent probe 7-octadecylamino-4-nitrobenz-2-oxa-1,3-diazole (NBD-NH-C18) and was allowed to bind to host cells (HEp-2, BALB-3T3) at 4 degrees C. The effect of lipophosphoglycan (LPG), isolated from Leishmania donovani, on virus fusion was investigated by incorporation of LPG (0, 5, 10 or 20 microM) into the host cell membrane (HEp-2) before addition of SV. LPG did not affect the number of SV bound per cell. After incubation at 37 degrees C for 15 min without LPG, CLSM revealed a redistribution of NBD-NH-C18 from the SV envelope to the host cell membrane and an increase in average fluorescence intensity, indicating dequenching. ICS analysis of images obtained after incubation at 37 degrees C showed an increased mean cluster density to 260% of the value at 4 degrees C, reflecting the disappearance of labeled SV from the cell surface and diffusion of NBD-NH-C18 into the host cell membrane. Preincubation of the cells with LPG inhibited the temperature-induced redistribution and dequenching of NBD-NH-C18 in a concentration-dependent manner, with a total inhibition of fusion at 20 microM LPG. Together, the results demonstrate that CLSM combined with ICS is a powerful tool for studies of fusion of enveloped viruses with individual host cells and that LPG inhibits the fusion process at or before the hemifusion (lipid mixing) stage of SV interaction with cells.

4-Chloro-7-nitrobenzofurazan↗

PubMed2000

Imaging size-selective permeation through micropatterned thin films using scanning electrochemical microscopy

This paper describes a new approach for quantification of rates of molecular transport through patterned, or otherwise heterogeneous, porous films supported on conductive substrates. Scanning Electrochemical Microscopy (SECM) has been used to image molecular sieving of redox active probes by thin, electropolymerized films of Fe(5-amino-1,10-phenanthroline)3(2+) on micropatterned and microdisk array electrodes. Films as thin as 12 nm completely block redox mediators with average molecular diameters greater than 12 A, whereas smaller diameter probes (radii 5-8 A) were observed to permeate selectively. SECM tip currents measured for three different redox permeants/mediators are observed to decrease with increasing polymer thickness, consistent with a transport model that includes partitioning into and diffusion within the polymer films. Permeabilities, PDf, within the poly[Fe(5-NH2-phen)3(2+)] films have been quantitatively determined from the SECM tip currents and are in excellent agreement with data previously obtained from rotatingdisk electrochemistry. This new methodology provides a versatile approach for quantitative investigation of membrane transport and permeation selectivity with good lateral spatial resolution.

Journal Article↗