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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

Whole mount in situ detection of low abundance transcripts of the myogenic factor qmf1 and myosin heavy chain protein in quail embryos.

We describe a whole mount in situ hybridization procedure to detect and localize low abundance transcripts (qmf1) and myosin heavy chain proteins in quail embryos. The critical factor in transcript detection was the extent of proteinase K digestion. Optimal digestion increased probe accessibility and reduced background. The use of digoxigenin-labeled probes and immunological detection with anti-digoxigenin-alkaline phosphatase conjugated antibody allowed signal development in 6-10 h, unlike the 7 days required using 35S-labeled probes. Myosin heavy chain proteins were detected using immunofluorescence and confocal laser scanning microscopy to allow precise localization of signal within developing embryos.

Animals↗
PubMed1992

Microleakage in various dentin bonding agent/composite resin systems.

One important consideration in the selection of a dentin bonding agent/composite resin system is its resistance to marginal leakage. The purpose of this study was to compare both the extent and the pathways of marginal leakage for four currently available dentin bonding agent/composite resin systems. Class 5 restorations were placed in the buccal and lingual surfaces of 20 extracted human teeth. Specimens were subjected to thermal stress before being placed in silver nitrate solution. They were then sectioned longitudinally and observed under a light microscope. Selected samples were further studied using scanning electron microscopy (SEM) and energy-dispersive x-ray analysis (EDX). Different systems exhibited different leakage patterns. Findings suggest that the smear layer should be either conditioned or removed prior to dentin bonding agent application to provide optimal resistance to microleakage.

Composite Resins↗
PubMed2005

[Enhanced BK(Ca) single-channel activities in cerebrovascular smooth muscle cells of simulated microgravity rats.].

The aim of the present study was to investigate the changes in single-channel currents of large conductance calcium-activated potassium channels (BK(Ca) channels) in cerebral vascular smooth muscle cells (VSMCs) of rats after 1-week simulated microgravity. Sprague-Dawley rats were subjected to tail-suspension (SUS) to simulate cardiovascular deconditioning due to microgravity. Cytosolic calcium ([Ca(2+)](i)) was examined by laser-scanning confocal microscopy with calcium-sensitive-dye Fluo-3/AM as fluorescent probe. Single-channel currents of BK(Ca) channels were measured with cell-attached membrane patches bathed in symmetrical high potassium solution. The [Ca(2+)](i)i level was significantly higher in cerebrovascular myocytes of SUS than that of control (CON) rats. The probability of open (Po) and the mean open time (To) of BK(Ca) channels in cerebral VSMCs significantly increased in SUS as compared with CON. However, there were no significant differences in the unitary conductance and mean close time (Tc) between the two groups. The results obtained suggest that both the elevated [Ca(2+)](i) and enhanced single-channel activities of BK(Ca) channels in cerebral VSMCs might be among the electrophysiological mechanisms that mediate the increased vasoreactivity and hypertrophic change in cerebral arteries during adaptation to simulated microgravity in rats.

English Abstract↗
PubMed1989

A histological study of calcium pyrophosphate dihydrate crystal-deposition disease.

Synovial, meniscal, articular cartilage, and other connective tissue from fifty-seven patients who had calcium pyrophosphate dihydrate crystal-deposition disease was examined by light microscopy, electron microscopy, and electron-probe microanalysis. Safranin O-positive hypertrophic chondrocytes that contained proteoglycans were observed in the tissues of each patient. Microcrystals that were suggestive of early precipitation of crystals were found in the degenerating matrix surrounding hypertrophic chondrocytes. The matrix contained electron-dense amorphous material, including proteoglycans and debris of cellular components. The microcrystals were often seen in contact with degenerating collagen fibers. There was never any histological evidence of formation of crystal in the areas that had no hypertrophic chondrocytes. Chondrocytes of this kind, surrounded by characteristic degenerating matrix, were never observed in the articular tissue from sixty-one patients who had only osteoarthritis. On the basis of our results, we speculate that electron-dense amorphous material containing proteoglycans and debris of cellular components, and the degenerating collagen fibers that were seen around the hypertrophic chondrocytes, may play important roles in the formation of calcium pyrophosphate dihydrate crystals.

Adult↗
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↗
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

Low temperature techniques in biomedical microanalysis.

Many diseases are associated with a change in the distribution of diffusible ions at the cell or tissue level. These diseases can profitably be studied by X-ray microanalysis. This technique for the study of ion distribution requires the use of cryoprepared specimens. Analysis at low or medium resolution can be carried out on thick or semi-thick cryosections, or on frozen-hydrated or freeze-dried embedded bulk samples. Such analyses are particularly useful in the initial stages of an investigation, or when many data from a large number of samples have to be acquired. Quantitative analysis is then usually carried out with the peak-to-local background method: by taking the background in the same energy range as the characteristic peak, an intrinsic correction for absorption of X-rays within the sample is made. X-ray microanalysis of cultured cells prepared by freeze-drying can also be carried out in this way. Analysis at high resolution has to be carried out on thin sections: cryosections, or sections of freeze-substituted or freeze-dried embedded tissue. For the latter type of specimens, the use of low-temperature embedding methods may have important advantages. Quantitative analysis of thin sections is carried out by the established continuum method.

Animals↗
PubMed1987

Industrial problem solving with microbeam analysis.

The objective of this paper is to provide an overview of the microbeam analytical techniques and to help select the appropriate one to solve complex problems often arising in today's high-tech industries. Case histories are given to show how renowned analytical service laboratories and microbeam experts formulated their strategies to approach a real life problem, what type of conclusions were deduced from the data and, finally, how the problem was solved.

Electron Probe Microanalysis↗
PubMed1985

Wave-length dispersive microprobe analysis of coated samples of bulk tissues.

Hypertrophic scars contain highly pleomorphic cells, including many from the erythrocytic series which have been extravasated. The conventional visual mode of SEM cannot distinguish the cell types with certainty except in the case of typical biconcave disc-shaped erythrocytes. Microprobe elemental analysis might be used to differentiate one type from another on the basis of iron and possibly phosphorus (for nucleated cells). Using coated specimens (gold or gold-palladium) precludes simultaneous visual mode SEM with EDX because of energy line interference with phosphorus and other elements. However, wave-length dispersive analysis offers minimal or no interference, and a coated specimen offers the use of a simultaneous visual mode. We wished to determine if useful elemental data could be obtained from specimens previously prepared only with the purpose of SEM mode studies. Therefore they were not prepared according to contemporary optimal methods. Analysis demonstrates that one group of cells contains 45% or more (dry weight concentration, absolute) iron as opposed to markedly low values in other cell types. Values for phosphorus do not appear essentially different among the cell types except in the case of standard erythrocytes where it is very low. Calcium and sulfur content was also examined. Sulfur might be useful in identifying another cell type in the hypertrophic scar. Using cells and matrix in developing deer antler for control values, the ratio of calcium to phosphorus found in the mineralizing matrix was essentially the predicted value. It is concluded, therefore, that even with a substantially heavy coating of gold, values for the elements tested (Fe, P, Ca, S) are not seriously compromised.

Animals↗
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↗
PubMed1983

Cystic fibrosis - ultrastructural and microanalytical studies.

This review summarizes the contribution of electron microscopy and X-ray microanalysis to the study of the pathogenesis and the diagnosis of cystic fibrosis (CF). Light and electron microscopical studies of the most severely affected exocrine glands of CF patients (pancreas, tracheobronchial submucosal glands) generally show dilatation of the ducts and inspissation of mucous material. The ultrastructure of the acinar cells, however, is normal. Functional abnormalities in the gland can be demonstrated by X-ray microanalysis of the secreted fluid. In the search for the basic defect in CF use is often made of cultured fibroblasts. The ultrastructure of CF fibroblasts is basically normal. X-ray microanalysis shows significantly lower Na and higher Ca levels in CF fibroblasts. Several of the biological effects of the 'CF factor(s)', supposedly present e.g. in the serum of CF patients or in CF fibroblast culture medium, can be demonstrated by electron microscopy or X-ray microanalysis. Ultrastructural and X-ray microanalytical studies of 'animal models' for CF have shown that pathological changes in exocrine glands resembling some of those seen in CF patients, can be induced by interference with the nervous regulation of exocrine secretion.

Animals↗