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At least 1,495 records · Page 83Linked to original sources
PubMed1992

X-ray microanalysis of bulk hydrated specimens of neoplastic and non-neoplastic human urothelium.

Specimens of neoplastic and non-neoplastic human urothelium were rapidly frozen against a copper block immersed in liquid nitrogen, planed in a cryoultramicrotome and then examined by low-temperature scanning electron microscopy (LTSEM) following coating by aluminium. Energy dispersive X-ray microanalysis (XRMA) was performed on the superficial urothelial cells and on gelatin blocks mounted in parallel which had known concentrations of sodium, potassium, chloride, and phosphorus. The neoplastic urothelial cells had significantly less phosphorus (P less than 0.05) than non-neoplastic cells and the ratios K+/P,K+/Na+, and K+/Cl- were significantly higher in neoplastic cells than in non-neoplastic cells (P less than 0.00001). These results are consistent with those expected in cells with a sustained increase in intracellular pH caused by stimulation of Na+/H+ ion membrane exchange.

Electrolytes↗
PubMed1996

["Carious" and "noncarious" lesions of the hard dental tissues. Ultrastructural (SEM) and microanalytical (EDS) analyses of teeth from the 3rd century B.C].

The study was carried out on 80 teeth (70 of permanent dentition and 10 of primary one) of mandibular and maxillary bones. The teeth owned to subjects lived in the III c.b.C. in Sicily, and they were found in Naxos necropolis. The teeth were examined as far as carious and non carious lesions, then they were prepared for instrumental analyses by Scanning Electron Microscopy (SEM) and Energy dispersed X ray spectrometry (EDS). To an objective examination of the sample no caries were detected in the teeth sample apart one tooth, on the other hand there was an extensive occlusal abrasion, from a macroscopic point of view there were no difference as far teeth morphology. SEM examination pointed out all around dentinal tubules a circle of sclerotic dentin as reaction to occlusal wear. The amelocemental junction showed from a ultramicroscopic point of view an overlap of cementum onto enamel. EDS analysis pointed out a higher P concentration on the crown versus the root in all the teeth of the sample.

Dental Caries↗
PubMedDate not supplied

Non-calcified breast particles: a possible new marker of breast cancer.

Malignant and benign human breast tissue containing radiographic evidence of calcifications were studied by means of scanning electron microscopy and x-ray microanalysis. In addition to the well-known calcium-phosphorus deposits, discrete particles containing calcium with little or no phosphorus and calcium in combination with other elements were found. Moreover, particles containing elements other than calcium were observed. These include Al, Fe, Mg, Si, Cu, Zn, Cr, Ti, Ni, Pb, Au, Ag, Mo, Cl, I. Some of these "noncalcifications" contained a single element, others a combination of elements. These findings differ from the view that all breast particles are calcifications. Further study could lead to the development of new diagnostic techniques for the detection of breast cancer and/or chemotherapeutic agents.

Breast Neoplasms↗
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↗
PubMed1997

Tape stripping of human stratum corneum yields cell layers that originate from various depths because of furrows in the skin.

Tape stripping of human stratum corneum is widely used as a method for studying the kinetics and penetration depth of drugs. Several factors can influence the quantity of stratum corneum that is removed by a piece of tape, such as the manner of tape stripping, the hydration of the skin, cohesion between cells, body site and interindividual differences. However, few data are available about the influence of furrows in the human epidermis on the tape-stripping technique. In this study, we investigated the efficacy of tape stripping in removing complete cell layers from the superficial part of the human stratum corneum. A histological section of skin that was tape-stripped 20 times clearly showed nonstripped skin in the furrows, indicating persistent incomplete tape stripping. Replicas of tape-stripped skin surface demonstrated that even after removing 40 tape strips the furrows were still present. We validated the tape-stripping method further with X-ray microanalysis in the mapping mode by scanning electron microscopy, using a TiO2-containing compound as a marker. TiO2 applied to the skin before the tape-stripping procedures was still present after the tenth tape strip, and was specifically located on the rims of the furrows. We emphasize that results from studies using the tape-stripping method have to be viewed from the perspective that cells on one tape strip of the stratum corneum may be derived from different layers, depending on the position of the tape strip in relation to the slope of the furrow, and such results should be interpreted with considerable caution.

Adhesives↗
PubMed2002

Scanning electrochemical microscopy of living cells. 3. Rhodobacter sphaeroides.

The scanning electrochemical microscope (SECM) was used to probe the redox activity of individual purple bacteria (Rhodobacter sphaeroides). The approaches developed in our previous studies of mammalian cells were expanded to measure the rates and investigate the pathway of transmembrane charge transfer in bacteria. The two groups of redox mediators (i.e., hydrophilic and hydrophobic redox species) were used to shuttle the electrons between the SECM tip electrode in solution and the redox centers inside the cell. The analysis of the dependencies of the measured rate constant on formal potential and concentration of mediator species in solution yielded information about the permeability of the outer cell membrane to different ionic species and intracellular redox properties. The maps of redox reactivity of the cell surface were obtained with a micrometer or submicrometer spatial resolution.

Cell Membrane↗
PubMedDate not supplied

Fabrication and observation of a standard sample for near-field optical microscopy.

We fabricated a standard sample for a near-field optical microscope using scanning probe lithography. The sample contains a wedged pattern, which allows the measurement of various sizes within one image. The optical resolution of our near-field optical microscope has been evaluated as 40 nm, which was obtained by measuring the narrowest separable gap width of the wedged pattern. Thus a standard sample containing the wedged pattern enables clear evaluation of the resolution.

Journal Article↗
PubMed1994

Radiopaque deposits surrounding a contact small-caliber gunshot wound.

Primer residue typically contains some combination of lead, antimony, or barium, whereas bullet residue from nonjacketed bullets is 70-100% lead. The amount of lead particles produced by low-velocity bullets (projectile residue) may be exceedingly high. Copper- or brass-coated bullets generate an admixture of lead and copper particles whereas jacketed and semijacketed bullets produce the least amount of lead particles and only a small amount of copper-containing residue. We recently studied a suicidal contact small-caliber gunshot wound with an unusual amount of bullet residue deposited on the epidermal margins and within the wound track. The entrance wound was encircled by radiopaque particulate material visible on the postmortem radiograph. Soft radiography delineated the material to the wound track and adjacent epidermis. Scanning electron microscopy with energy-dispersive analysis of x-rays identified the principle element as lead.

Adult↗
PubMed2000

Physical degradation of wheat straw by the in-vessel and windrow methods of mushroom compost production.

Mushroom compost manufacturers in Ireland are moving away from the traditional outdoor phase I windrow method, favouring in-vessel production. Composters and growers have reported better quality compost with faster spawn run and higher yields produced by this process. In the present study, physical examination of samples highlighted differences when comparing the windrow and in-vessel methods of compost production. Observations using scanning electron microscopy suggest that the cuticle of wheat straw from in-vessel production is damaged during phase I, peeling away from the surface in fragments, and exposing the epidermis. Changes in silicon levels on the straw surface acted as a marker for cuticle damage when comparing both composting systems. Cuticle damage may be important during composting and afterwards, as substrate colonisation is faster, and consequently spawn run is shorter. The phase I compost microbial community is altered by the in-vessel technique, producing a predominantly thermophilic bacterial flora in contrast to the mesophilic and thermophilic bacteria and fungi found in windrow phase I compost. These differences may be significant in mushroom compost production.

Agaricus↗
PubMed1993

Chemical nature and distribution of calcium compounds in radiolucent gallstones.

A high failure rate for radiolucent cholesterol gallstones to dissolve with oral bile acids may be due to the presence of insoluble calcium compounds. Twenty sets of radiolucent gallstones, 7-20 mm in diameter, obtained from 20 patients undergoing cholecystectomy, were cut, and the outer surface, outer rim, middle portion, and central core areas were scanned for calcium by energy-dispersive X-ray microanalysis (EDX) and scanning electron microscopy (SEM). Scrapings from the four areas of each stone were analysed by infrared spectroscopy. A sample of the crushed stone was used for chemical estimation of cholesterol. Eleven (55%) of the 20 cholesterol (84-96% dry weight of cholesterol) stones showed presence of calcium by EDX; the distribution was peripheral in 5, homogeneous in 4, and central in 2. The chemical compound was calcium bilirubinate in 10 and calcium carbonate in 8 stones. Calcium compounds are present in a high proportion of radiolucent gallstones considered suitable for chemodissolution by conventional criteria. Their unrecognized presence may explain the high failure rate of such stones to respond to medical therapy.

Adult↗
PubMed1993

Microstructural changes of human enamel surfaces by brushing with and without dentifrice containing abrasive.

Toothbrushing with and without dentifrice containing abrasive was performed on human enamel pieces attached to resin plates exposed to the oral cavities of 3 human subjects for 8 weeks. The effects on the ground enamel surfaces with engraved scratches were examined by scanning electron and scanning laser microscopy. Brushing with such a dentifrice caused smaller scratches to disappear, large scratches to expand and new microwear to appear; in some samples, prism structures were exposed. Under brushing without dentifrice, these scratches were protected by an organic pellicle with mineral deposits, and also the experimental surface was entirely covered with these membranous deposits. The results indicate that toothbrushing with no dentifrice but saliva induces an organic-mineral protective membrane on the enamel surface. The membrane may increase the enamel resistance to caries. On the other hand, the use of abrasive-containing dentifrice causes slight abrasion with microwear. This roughness may contribute to the formation of dental plaque.

Adult↗
PubMed1992

Human neutrophil response to short-term exposure to F-75 cobalt-based alloy.

The effect of biomaterials on the activation of human neutrophils was studied. Human neutrophils were incubated with F-75 cobalt-based alloy or polystyrene microspheres of a nonphagocytosable size with two times total neutrophil plane surface area. Scanning and transmission electron microscope (SEM, TEM), energy dispersive x-ray microanalysis (EDX), and graphite furnace atomic absorption spectroscopy (GFAAS) were used to analyze changes in cellular morphology and metal content. This report presents evidence that human PMNs display morphological changes related to foreign material challenge, including activation on F-75 bead surfaces, pinocytosis of corrosion products, formation of intracellular vacuoles, degranulation, etc. Moreover, when PMNs were present, the corrosion release rate of F-75 increased as much as three times over cell-free controls.

Adult↗
PubMed1999

Crystalloid architecture of a sialolith in a minor salivary gland.

A sialolith from a minor salivary gland of the mucosa of the upper lip was studied morphologically and analytically. Under stereoscopic microscopic visualisation, no core or any concentric laminar structure was found in the sialolith and it had a transparent glassy appearance. Scanning electron microscopy revealed differences between the internal structure of the sialolith and its external structure. No microbes were observed but some mineralized inclusion bodies were seen. X-ray diffraction indicated the absence of inorganic crystals in the sialolith, while energy dispersive x-ray microanalysis revealed a high content of S followed by Ca, Si and Na and little and scarce P on the fracture surface, with S, Na, Ca and P being distributed throughout the external coating of the sialolith. The results suggest that the sialolith was young and consisted of a crystalloid body with an incipient coating undergoing calcification.

Adult↗
PubMed2001

Internal contamination of a 2-component implant system after occlusal loading and provisionally luted reconstruction with or without a washer device.

BACKGROUND: Microbial internal contamination of oral implants has been suggested as being responsible for inflammatory infiltration of peri-implant tissues at the fixture-abutment interface of 2-stage and 2-component implant systems; it is also considered as a potential source of pathogens. The present in vivo study evaluated contamination of the inner abutment-implant retaining screw, after occlusal loading and provisionally-luted reconstruction with or without a washer device. METHODS: Eight 2-component oral implants sealed with an o-ring silicon washer device and 9 without a seal were placed in 7 patients with high oral hygiene standards. Two months after prosthetic reconstruction, crowns and internal screws were removed, and organic and inorganic screw contamination was examined by scanning electron microscopy and energy dispersive x-ray spectroscopy (EDS) analysis. RESULTS: An amorphous and crystalline contamination, suggestive of calcium and phosphate compounds, was seen on all screw surfaces. Microbial contamination was more frequently observed in the unsealed group. No differences in bacterial morphotypes were observed between the sealed and unsealed implants. Cocci were the most representative morphotypes, while rods were seldom seen. CONCLUSIONS: In clinical situations, leakage occurs at the implant-abutment interface, although bacterial contamination is limited in patients with high oral hygiene standards. Contamination may be reduced by using a washer device.

Analysis of Variance↗
PubMed1995

High-resolution FEISEM detection of DNA centromeric probes in HeLa metaphase chromosomes.

HeLa metaphase chromosome spreads were hybridized with centromeric biotinylated DNA probes and detected with gold-conjugated anti-biotin antibodies. Chromosomes were observed by an in-lens field emission scanning electron microscope (FEISEM), which permits detection of biological samples without any coating. DNA probes were well localized in the centromeric region of chromosomes and there was clear discrimination between 10 nm fibers that hybridized to DNA probes and those that did not hybridize. This approach shows that in situ hybridization can be directly visualized at the FEISEM level by evaluating only secondary electron emission, which allows physical localization of the hybridized probe with high resolution so that backscatter detection represents only a control. Because chromosomes maintain the 10-nm fiber organization after in situ hybridization procedures, our data suggest that this fiber represents the lowest order of chromatin arrangement that permits transitory DNA denaturation.

Centromere↗
PubMed1996

Electron probe X-ray microanalysis of the elemental composition of the pineal gland of young adults and aged rats.

Fractures of deep-frozen and freeze-dried pineal glands were analysed for elemental composition by means of X-ray microanalysis with a scanning electron microscope. The results from young adults (3 months old) were compared with those from aged animals (24 months old); significant increases in S, Ca, Al, Si, and Fe were observed in aged animals when compared to young adults. There were no significant differences with Na, Mg, Cl, K, Ti, Cr, Mn, Ni, Cu, Zn, whereas a decrease of P was observed in aged animals when compared to young adults. Whether the changes observed in elemental composition have a direct effect on the activity and production of metalloenzymes and the overall physiology of the pineal gland are discussed.

Aging↗
PubMed1991

Effect of zinc upon cell attachment and proliferation on periodontally-diseased root surfaces.

The purpose of this study was to determine the effect of zinc ions on fibroblast attachment to periodontally-diseased root surfaces in vitro. Extracted periodontally-diseased teeth were treated with 0.5% ZnCl2 by iontophoresis at 0.5 mA for 2 to 6 minutes. Control groups were untreated diseased and untreated healthy teeth. Sections of the root underlying the pocket were cut from the diseased teeth. The specimens were incubated for 18 hours with L929 mouse fibroblasts, then transferred and incubated in cell-free medium for 48 hours. Cell attachment was evaluated by cell counts and scanning electron microscopy (SEM). Root surfaces were sampled with an acid-etch technique and zinc was measured with an atomic absorption spectrophotometer. Two samples from each group were examined for cell attachment with SEM. Data were analyzed using the appropriate statistical methods. The results showed that diseased, untreated root surfaces had significantly fewer cells attached; however, zinc iontophoresis did not significantly improve cell attachment to the diseased root surfaces. Zinc analysis showed that diseased, untreated root surfaces had a higher zinc content than healthy ones. SEM examination showed striking differences in cell attachment to healthy versus diseased root surfaces. The data indicated that zinc iontophoresis did not significantly enhance cell attachment to root surfaces of diseased teeth.

Cell Adhesion↗
PubMed1999

Characterization of the interface between prefabricated gold copings and cast dental alloy in implant restorations.

The objective of this study was to analyse the characteristics of the metal interface between the casting of a dental noble alloy and prefabricated gold copings (OCTA-ITI Implant System) after the fabrication procedures of a prosthetic implant-retained superstructure. The microscopical investigation, performed by optical microscopy (OM) and scanning electron microscopy (SEM), of the region around the cylinder after the casting process and the subsequent porcelain firing procedures showed the presence of an ideal interface, including: i) maintenance of coping and casting alloy microstructures up to the interface, and ii) absence of interfacial reaction products. A low content of porosity (less than 3% by volume in average) was observed in the casting alloy bulk as well as at interface. The investigation by energy-dispersive spectroscopy (EDS) of the alloy composition close to the interface showed the presence of a minimal elemental interdiffusion, suggesting that an adequate compatibility between alloy and coping characterized the materials used. A small decrease of the prefabricated coping hardness was also observed after the casting and porcelain firing procedures.

Dental Abutments↗