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PubMed2004

Calcium phosphate formation on the phosphorylated dental bonding agent in electrolyte solution.

The aim of the present study was to study the mineral formation on a phosphorylated dental bonding agent using a mineralization inductive solution. Clearfil Photobond, which contained phosphate monomer, was cured by photo-irradiation and heat treated, and was then immersed in Hanks' balanced salt solution (HBSS) with pH = 7.4 for 1, 3, 5, 7, 14, and 28 days at 37 degrees C. The white substances were deposited on the phosphorylated polymer, i.e. cured Photobond disk, after the immersion in HBSS. The white substances become visible after 3 days immersion. After 7 days immersion, surface of the phosphorylated polymer disk was almost covered with white substance layers. The measurement of white substances by means of X-ray diffraction, Fourier-transform infrared and electron probe microanalysis revealed that their main component was carbonate-containing hydroxyapatite. Scanning electron microscopy pictures showed that a large number of globules of hydroxyapatite were fused together, and that each globule was composed of a group of numerous thin-film form flakes uniting and/or clustering together. The results obtained in this study concluded that the presence of phosphonic acid and phosphate group of phosphorylated dental bonding agent enhanced the nucleation and growth of hydroxyapatite crystals on its surface.

Biocompatible Materials↗
PubMed1996

In vitro characterization of enamel epithelium and pulp cells in mouse tooth germs.

Mixed cell populations consisting of enamel epithelium and pulp cells obtained from 18-day embryonic mouse tooth germs were cultured in vitro. Epithelial cells and pulp cells were also cultured individually and examined. Isolated cells were cultured in alpha-MEM supplemented with 10% fetal bovine serum for up to four weeks and examined morphologically using histological procedures including immunostaining, light and electron microscopy, and electron probe microanalysis. The pulp cells proliferated and differentiated in the absence of epithelium, but the number of epithelial cells showed a strong dependence on the pulp cells. Pulp cells showing fibroblastic morphology in the mixed culture gradually became elliptical, and eventually transformed into spherical cells surrounded by a calcified extracellular matrix. Alkaline phosphatase (ALPase) activity was expressed on the pulp cells prior to calcification of the extracellular matrix, as shown by von Kossa's and alizarin-red staining. Calcification deposition, which is closely associated with thick banded type-I collagen fibrils, was shown to be composed of calcium and phosphorous using electron probe microanalysis. Type-I collagen immunoreactivity was detected on the extracellular matrix after two weeks of culturing. The present results show that the proliferation and differentiation of pulp cells, and subsequent calcification of the extracellular matrix occur in the presence or absence of epithelial elements, but that the proliferation of epithelial cells depends on the presence of pulp cells.

Ameloblasts↗
PubMed1997

Backscattered electron imaging of cultured cells: application to electron probe X-ray microanalysis using a scanning electron microscope.

We report a simple method to study the elemental content in cultured human adherent cells by electron probe X-ray microanalysis with scanning electron microscopy. Cells were adapted to grow on polycarbonate tissue culture cell inserts, washed with distilled water, plunge-frozen with liquid nitrogen and freeze-dried. Unstained, freeze-dried cultured cells were visualized in the secondary and backscattered electron imaging modes of scanning electron microscopy. With backscattered electron imaging it was possible to identify unequivocally major subcellular compartments, i.e. the nucleus, nucleoli and cytoplasm. X-ray microanalysis was used simultaneously to determine the elemental content in cultured cells at the cellular level. In addition, we propose some improvements to optimize backscattered electron and X-ray signal collection. Our findings demonstrate that backscattered electron imaging offers a powerful method to examine whole, freeze-dried cultured cells for scanning electron probe X-ray microanalysis.

Animals↗
PubMed1991

Absence of aluminium in Alzheimer's disease brain tissue: electron microprobe and ion microprobe studies.

Brain tissue from the frontal cortex and hippocampal formation, taken at autopsy or biopsy from 7 patients with Alzheimer's disease, was studied by two methods of microanalysis. One case of Down's syndrome was also studied. Electron probe microanalysis of the frontal cortex and Ammon's horn of the hippocampus showed no aluminium in the various cell organelles, especially in the lysosomes, although some aluminium was found in a few contaminating dusts. Ion microscopy, a method of extremely high sensitivity, also showed the absence of an aluminium signal.

Adult↗
PubMed2006

Preparation of stable alginate microcapsules coated with chitosan or polyethyleneimine for extraction of heavy metal ions.

Stable alginate microcapsules in dried form containing bis(2,4,4-trimethylpentyl) monothiophosphinic acid (HA) were prepared by coating of fresh alginate microcapsules with chitosan or polyethyleneimine (PEI). The thickness of coatings was estimated by electron probe microanalysis (EPMA), along with electron microscopy (SEM), as well as comparison of uptake percentage of coated and uncoated hollow capsules. Characterization of microcapsules was carried out by Ag(+) uptake experiments, destructive chemical analyses and thermogravimetric methods (TG and DTA). Chemical stability tests in HNO(3) and NaNO(3) media indicated that the coating with 4-double layer chitosan or mono-layer PEI led to an appreciable enhancement of impermeability in the range of pH > 1 or [Na(+)] < 1 M (mol dm(-3)). Unfortunately, multiple coating causes some extractant losses due to effect of physical stress during the coating; however, PEI-coated microcapsules nearly completely hold their extractant content. Stable extractive microcapsules have an appreciable potential for the selective removal of heavy metal ions.

Alginates↗
PubMed1986

Ca-pools involved in the regulation of cardiac contraction under positive inotropy. X-ray microanalysis on rapidly-frozen ventricular muscles of guinea-pig.

Electron probe microanalysis of rapidly-frozen small ventricular trabeculae of guinea-pig demonstrates that the distribution of total intracellular calcium varies under positive inotropy depending on the type of inotropic intervention. The sarcoplasmic reticulum (SR) (or part of it) localized at the level of the z-lines reveals high calcium accumulation at the end of diastole whenever a stimulus is followed by a contraction with a short time to peak of force. After paired pulse stimulation, only this cell compartment accumulates calcium at the end of diastole. Since this cell compartment is "Ca-empty" in muscles frozen during contraction, SR is considered to be the source of activator Ca. In several cases of inotropy (after application of ARL, caffeine or after lowering the extracellular Na+ concentration), calcium is also detectable on the mitochondria, suggesting that these organelles participate in slow regulation of cytosolic calcium. In some cases, total calcium located on the sarcomeres is increased. The interpretation of this finding is intriguing and requires the assumption of supplementary cytosolic Ca-sinks as yet unknown.

Animals↗
PubMed1976

Pulmonary mineral dust. A study of ninety patients by electron microscopy, electron microanalysis, and electron microdiffraction.

The results of a study of 90 patients are presented. Intrapulmonary mineral deposits were characterized by electron diffraction and electron probe microanalysis. Using this method, pneumoconioses may be distinguidhed from other pneumopathies. In cases of pneumoconiosis, there exists a specific relationship between the etiology of the dust exposure and the crystallographic characteristics of the intrapulmonary deposits. The nature of the deposits may be indicative of a specific type of pneumoconiosis. This method is particularly useful in differentiating between asbestos bodies and ferruginous bodies. The value of the method in general and its importance in the study of pneumoconiosis are discussed.

Asbestos↗
PubMed1974

Elemental analysis of asbestos fibers by means of electron probe techniques.

The identification and characterization of microparticles has become an important field of study in recent years due to their presence in the environment and association with pathogenesis. Asbestos fibers have been intensively studied for these reasons. Since conventional microscopy has not provided unique identification of these materials, electron probe microanalysis, which yields chemical data, has been utilized in conjunction with other techniques to provide the necessary answers.The options now available to undertake electron probe analysis are discussed with relation to their utilization for microparticle analyses. Two types of electron sources are available, thermionic and field emission. The x-ray spectroscopy requires the use of either wavelength-dispersive focussing crystal spectrometers or an energy-dispersive Si(Li) x-ray detector. Data are presented to demonstrate the feasibility of asbestos identification by using modified raw data obtained with a scanning electron microscope and energy-dispersive x-ray spectrometer. Further, the extension of the technique to other microparticle identification problems is discussed.

Air Pollutants↗
PubMedDate not supplied

Estimation of the copper-iron correlation in the liver under experimental conditions. A microscopic and microchemical study.

Liver obtained from copper-intoxicated rats was studied by electron microscopy and electron probe microanalysis. Large ultrastructural disorders in liver cells appeared at the level of lysosomes and mitochondria. Diffuse and aggregate copper granules were observed in the entire cell, but mainly in pericentrolobular and periportal zones. Probe analysis revealed an increased copper deposit, particularly during the chronic copper intoxication, and a very high concentration of iron gradually accumulated.

Animals↗
PubMed1979

X-ray analysis of pathological calcifications including urinary stones.

Electron-probe microanalysis (EPM) is an ideal technique with which to study biological calcification. It is particularly effective in identification of crystalline or non-crystalline deposits of minute size in tissues, and in detecting artifacts which may occur during tissue processing. Human aorta, aortic valves, tumours, joint fluid, and calculus specimens were analyzed via scanning electron microscopy (SEM), EPM, transmission electron microscopy (TEM), and selected-area electron diffraction (ED). Crystals found in the specimens were definitively identified by combined SEM-EPM. It is apparent that EPM is an invaluable tool that will potentially improve the acuity of 'in house' laboratory diagnosis of many pathological calcifications.

Aorta↗
PubMed2004

Potassium assay in blastomere of two-cell mouse embryo after equilibration and washing from cryoprotector.

The need for effective methods of cryopreservation of early mammalian embryos necessitates the study of the mechanisms of blastomere adaptation to the equilibration procedure and subsequent washing from the cryoprotector. The osmotic effects during these procedures can cause electrolyte imbalance in embryonic cells. Intracellular potassium concentrations at the stage of two-blastomere mouse embryo were studied by electron probe microanalysis.

Animals↗
PubMed1998

Electron microscopic observations and X-ray microanalysis of a multinucleated giant cell.

Giant cells and macrophages play important roles in defence and in reparative functions of the body. This paper describes a giant cell and macrophage present in an inflammatory mass in the temporal bone. X-ray microanalysis performed at the ultrastructural level revealed the presence of a very high iron content in the electron dense precipitates observed in both types of cells. The high iron content is probably due to phagocytosed haemosiderin, a breakdown product of free haemoglobin since there was evidence of haemorrhage present in the biological sections. As the tissue was chemically fixed, it also demonstrates that there is still a place for electron probe microanalysis in tissues (including archived specimens) which have undergone chemical fixation.

Adult↗
PubMed1998

Ultrastructural organization and microanalysis studies of deciduous enamel crystallites in regional odontodysplasia (RO).

The ultrastructural organization and chemical components of enamel crystallites in two deciduous teeth affected by RO, an uncommon developmental condition giving the tooth a ghost-like appearance, were investigated by scanning and transmission electron microscopy, X-ray diffraction, electron probe microanalysis and Fourier transform improved microspectroscopy. Pathologic mineralizations involving prismatic structures, which affected the size, shape and stoichiometric structure of crystallites and led to enhanced Mg/Ca and Na/Ca ratios and crystal defects, were observed. Local circulatory disorders may have caused this developmental anomaly.

Child, Preschool↗
PubMed1995

Chronic copper intoxication due to ingestion of coins: a report of an unusual case.

We report an unusual case of acute copper intoxication in a patient who died after swallowing more than 700 coins mainly of 1p and 2p denomination. At autopsy the liver showed fibrosis and extensive copper deposition was demonstrated in the histological sections. Electron probe microanalysis also confirmed the presence of copper in the hepatic tissue.

Copper↗
PubMed1987

The mechanism of acute cytotoxicity of triethylphosphine gold(I) complexes. I. Characterization of triethylphosphine gold chloride-induced biochemical and morphological changes in isolated hepatocytes.

Triethylphosphine gold complexes are effective therapeutic agents used for the treatment of rheumatoid arthritis. Many of those molecules are also highly cytotoxic in vitro and can inhibit DNA and protein synthesis. Preliminary experiments have indicated that triethylphosphine gold chloride (TEPAu) may induce the peroxidative decomposition of cellular membrane lipids. The purpose of these investigations therefore was to evaluate the role of lipid peroxidation in the mechanism of acute cytotoxicity of a gold(I) coordination complex, TEPAu, and to examine the early morphological and biochemical changes induced by TEPAu in suspensions of freshly isolated rat hepatocytes. TEPAu caused a rapid loss of cell viability at concentrations above 25 microM which was significantly different from that of control by 60 min and complete by 180 min of incubation. TEPAu also depleted cells of reduced glutathione (GSH) and increased the formation of malondialdehyde (MDA) by 60 min. Incubation of cells with either of the antioxidants, N,N'-diphenyl-p-phenylenediamine (DPPD) or promethazine blocked the formation of MDA but did not alter the time course of cell death or GSH depletion induced by TEPAu. TEPAu also caused a decrease in cellular NADPH and NADH by 10 min. Electron microscopy of hepatocytes exposed to TEPAu revealed early (5 min) formation of flocculent electron-dense precipitates within condensed mitochondria. These changes characteristically preceded cell death. Energy-dispersive electron-probe microanalysis indicated that the electron-dense precipitates did not contain detectable amounts of gold. TEPAu also caused a concentration-dependent decrease in cellular ATP and oxygen consumption in isolated rat hepatocytes. These data suggest that lipid peroxidation, as indicated by the formation of MDA, is probably not a major mechanism by which triethylphosphine gold complexes lethally injure cells. These data, therefore, suggest that mitochondria may be target organelles in TEPAu-induced toxicity to isolated rat hepatocytes.

Animals↗
PubMed1988

Collagen expression, ultrastructural assembly, and mineralization in cultures of chicken embryo osteoblasts.

A newly defined chick calvariae osteoblast culture system that undergoes a temporal sequence of differentiation of the osteoblast phenotype with subsequent mineralization (Gerstenfeld, L. C., S. Chipman, J. Glowacki, and J. B. Lian. 1987. Dev. Biol. 122:49-60) has been examined for the regulation of collagen synthesis, ultrastructural organization of collagen fibrils, and extracellular matrix mineralization. Collagen gene expression, protein synthesis, processing, and accumulation were studied in this system over a 30-d period. Steady state mRNA levels for pro alpha 1(I) and pro alpha 2 collagen and total collagen synthesis increased 1.2- and 1.8-fold, respectively, between days 3 and 12. Thereafter, total collagen synthesis decreased 10-fold while mRNA levels decreased 2.5-fold. In contrast to the decreasing protein synthesis after day 12, total accumulated collagen in the cell layers increased sixfold from day 12 to 30. Examination of the kinetics of procollagen processing demonstrated that there was a sixfold increase in the rate of procollagen conversion to alpha chains from days 3 to 30 and the newly synthesized collagen was more efficiently incorporated into the extracellular matrix at later culture times. The macrostructural assembly of collagen and its relationship to culture mineralization were also examined. High voltage electron microscopy demonstrated that culture cell layers were three to four cells thick. Each cell layer was associated with a layer of well developed collagen fibrils orthogonally arranged with respect to adjacent layers. Fibrils had distinct 64-70-nm periodicity typical of type I collagen. Electron opaque areas found principally associated with the deepest layers of the fibrils consisted of calcium and phosphorus determined by electron probe microanalysis and were identified by electron diffraction as a very poorly crystalline hydroxyapatite mineral phase. These data demonstrate for the first time that cultured osteoblasts are capable of assembling their collagen fibrils into a bone-specific macrostructure which mineralizes in a manner similar to that characterized in vivo. Further, this matrix maturation may influence the processing kinetics of the collagen molecule.

Animals↗
PubMed1982

A study of ultrastructural alterations in experimental non-A, non-B hepatitis by electron-beam analysis.

An electron-beam X-ray microanalysis was carried out on sections of liver biopsy specimens obtained from chimpanzees infected with non-A, non-B hepatitis. The microanalysis was concentrated over areas where typical derangement of the endoplasmic reticulum, with the formation of tubular forms possessing walls with electron-dense central membrane, was visualized. These tubular structures are regarded as the most notable pathological alteration in affected hepatocytes. However, the electron-probe microanalysis showed no deviation of the energy spectrum when compared with the background or control analysis.

Animals↗