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Results for “Electron Probe Microanalysis”

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PubMed1990

Scanning ion microprobe assessment of biological sample preparation techniques.

Different preparation techniques for high lateral resolution scanning ion microprobe imaging of biological samples have been investigated. The sharpest histological maps are obtained from chemically fixed and plastic embedded specimens. It is often problematic to correlate ultrastructure and bioaccumulation from analysis of frozen cut and lyophilized sections. The best compromise is to resin-embed frozen samples in order to get a perfectly flat section from tissue where the in vivo ion distribution is maintained. Use of the University of Chicago Ion Microprobe gave us the ability to observe the relative ion translocations induced during sample preparation. As an example, we show the rapid decrease of intracellular K+/Na+ ratio through a fast frozen blood droplet.

Blood Cells↗
PubMed1990

[Shape memory alloys for orthodontic use studied with electron beams].

Shape memory alloys, which have the ability to be deformed into a temporary shape and then returned to its original shape giving useful elastic forces, are used in orthodontics field as shaped archs and springs. Their characteristics offer high potentiality to produce new orthodontics devices and to use in implantology. Using different analysis techniques with focussed electron beams, Authors have investigated on the superficial topography, alloy structural composition and on the absorbed elements of superficial layers of Nitinol orthodontics archs. SEM analysis have shown a compact and finished surface. PIXE analysis has quantized the atomic alloy composition in 55% and 45% on nickel and titanium, respectively. Auger spectroscopy and ion sputtering technique have shown that in surface of new archs oxygen and carbon are present up to about 300 A depth.

Alloys↗
PubMed1988

Ethanol induced skeletal muscle degeneration--role of calcium.

The ethanol induced skeletal muscle degeneration is multi-factorial. The morphological changes of the skeletal muscle are more pronounced in the mitochondria. The excessive concentration of calcium in the mitochondria, as shown by the electron-probe micro-analysis, within the first week of ethanol intoxication, even before the appearance of ultrastructural changes suggests that the calcium influx provokes the mitochondrial degeneration.

Alcoholism↗
PubMed1988

Corneal dystrophy in Fischer 344 rats.

A spontaneous degenerative lesion of the cornea resembling calcific band keratopathy in man has been observed in 10-15% of the F-344 rats (aged 35-300 days) purchased from a private vendor's closed breeding colony. The lesion appears clinically as punctuate to linear superficial corneal opacities located in the interpalpebral fissure of one or both eyes. Occasional roughening, bleb formation, or pitting of the corneal surface resembling superficial ulcers may be observed. The lesion occurs in both sexes. It is rarely associated with inflammation or irritation. Histologically, it consists of mineral deposits along the epithelial basement membrane and Bowman's space, some of which are large enough to disrupt or destroy portions of the basilar epithelium. Energy dispersive X-ray analysis of the deposits proved them to be composed of calcium and phosphorus. Electron microscopic examination revealed a variety of extracellular laminated and crystalline arrays similar to those seen in humans with band keratopathy. The etiology of the lesion is as yet undetermined. A genetic-associated susceptibility due to hypercalcemia may be involved.

Animals↗
PubMed1987

Development of ocular inserts for cattle.

Ring shaped ocular inserts have been developed to administer a therapeutic level of tylosin tartrate throughout a five day period to treat pinkeye in cattle. The inserts are based on polyvinyl chloride rings which are dip coated with a copolymer containing the antibiotic (tylosin tartrate). Scanning electron microscope (SEM) characterization of surfaces has been of value to evaluate the presence and extent of surface flaws in the hydrogel coating, and to contribute to improvement in fabrication of the rings to insure the establishment of satisfactory seals at joints, uniformity of microporosity and cross sections, and the absence of significant cracking or flaking. In vitro release rates were determined using thin layer chromatography techniques, and rates were seen to be above a few micrograms of antibiotic per hour for experiments as long as nine days at simulated tear rates as high as 2 milliliters per hour.

Animals↗
PubMed1986

[Asbestosis of the bladder neck and prostate. Reflections on 2 cases].

Ingested asbestos is mainly excreted in the urine. Marked impregnation of bladder neck in a patient working in an asbestos factory was diagnosed initially as a tuberculosis lesion on the granulomatous histologic appearance. Asbestos fibers were counted by electron microscopy. This appears to be the first case of this type reported and possible causal relations and histopathologic findings are discussed. Also reported is a patient with prostatic cancer, and chronic pulmonary asbestosis, treated by adenomectomy using an upper approach 15 years previously. The cancer was of the prostate transitional cell type. A causal relation could not be proved but other such cases should be investigated, to determine a possible link between the lesion and industrial fibers.

Adult↗
PubMed1986

Calcification in aging canine aortic valve.

Aging changes of aortic valves are thought to underlie the mechanism of calcification, which leads to calcific aortic stenosis in humans. The study of calcification in the aging valvular connective tissue has been hindered by the lack of a suitable animal model. In search of the model, canine aortic valves demonstrated age changes including calcification remarkably similar to those in humans. The mechanism of calcification was studied in the aortic valves of aged Beagles by electron microscopy. Fibroblasts in the canine aortic valves showed the most prominent age changes. The cells accumulated numerous residual bodies and appeared to disintegrate. The resultant membranous cellular degradation products which sequestered in the extracellular space were the nidi of calcification. It appeared that the membrane of cell debris played an important role in calcification. Canine aortic valve is an ideal model for the study of calcification in relation to aging of the valvular connective tissue.

Aging↗
PubMed1987

Use of scanning electron microscopy and energy dispersive X-ray analysis (SEM-EDXA) in identification of foreign material on bullets.

The authors report two cases in which examination of foreign material embedded in or adherent to bullets provided critical information in the reconstruction of a crime scene. Analysis of small particles by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDXA) can be accomplished without destruction or injury of the particles. In one case, the detection and identification of mineral fragments embedded near the nose of a bullet provided conclusive evidence that the bullet had ricocheted from a fireplace before striking the victim. In the second case, analysis of particles from two bullets identified them as them as bone fragments, thus proving which shots fired from a police officer's gun had killed a suspected burglar. SEM-EDXA has not been widely used to identify such material on bullets, but should be considered a potentially powerful tool in forensic science.

Adolescent↗
PubMed1987

Automated gunshot residue particle search and characterization.

The main disadvantage to gunshot residue (GSR) particle analysis utilizing scanning electron microscope/energy dispersive X-ray (SEM/EDX) instrumentation has been the excessive operator time required for search and identification. This study uses an automated particle search and characterization program for unattended GSR search and identification. This system allows for automatic matrix search, particle sizing, chemical typing, and spectral aquisition with subsequent storage of data to disk for later operator review and verification. This work describes various aspects of the program, determines appropriate parameters adequate for both unique and characteristic GSR particle identification, and evaluates the reliability of data obtained. Samples are collected via the tape lift method from test-firings of .38, .32, .25, and .22 caliber handguns at time after firing intervals of 0 to 6 h. Unique GSR particles are consistently and correctly identified by this method on tape lift samples taken up to 4 h after firing. False positive results of unique GSR particles are not encountered on control handblank samples. This technique appears to provide the forensic science community with an operator-free method of reliable GSR particle search and an improved analyst-time-per-case ratio.

Electron Probe Microanalysis↗
PubMed1985

Digital processing of electron energy loss spectra and images.

Processing in electron energy loss spectroscopy involves both data acquisition and analysis. The interface of an analytical electron microscope to a laboratory computer with a satellite microcomputer dedicated to data acquisition results in a system with a high degree of flexibility. In spectrum acquisition, channels may be selected around specific core edges, or dwell times may be varied continuously as a function of energy loss to reduce the dynamic range of the signal. Data transfer to the host computer allows further analysis such as the removal of plural scattering by spectral deconvolution. Elemental maps and line-scans can be recorded with real-time processing of energy loss data at each pixel. Images may be analyzed to provide quantitative information by means of pixel intensity histograms. If parameters for the background are stored at each pixel, the image data may sometimes be further processed to improve the signal-to-noise ratio.

Computers↗
PubMed1985

Apatite-type crystal deposition in arthritic cartilage.

Osteoarthritis or 'Joint Failure' is a multi-factorial disease with a final common pathway of cartilage degeneration and bone eburnation. The association of arthritic disease and joint degeneration with the deposition of sodium urate crystals in gout and calcium pyrophosphate crystals in pseudogout (chondrocalcinosis) is clinically well established. Electron microscopy coupled with electron probe analysis has revealed the presence of various other calcium phosphate crystals in joint tissues and fluids. We have found three new morphological types of apatite crystals in human articular cartilage which are too small to be detected by X-rays of human joints or even by light microscopy of joint tissues. Two morphologically distinct types of apatite crystals in articular cartilage are associated with extracellular matrix vesicles formed from the cell processes of chondrocytes. 'Cuboid' crystals, which are found in the pericellular regions near the surface zone of articular cartilage, appear to be a variant of apatite and may even be 'Whitlockite' because there are traces of magnesium present. There are increased numbers of these microscopic 'cuboid' crystals (Type II) and Mineral Nodules (Type I) in arthritic cartilage and this is coupled with increased numbers of matrix vesicles and alkaline phosphatase activity. Clusters of fine needle-shaped apatite crystals (Type III) found on the surface of articular cartilage are not associated with matrix vesicles. Thus some forms of osteoarthritis are closely associated with apatite type crystal deposition and may imply abnormal mineral formation in articular cartilage as a pathogenic mechanism.

Apatites↗