Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Electron Probe Microanalysis”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,261 records · Page 70Linked to original sources
PubMed1980

Electron probe analysis of cultured vascular smooth muscle.

Mitochondrial and cytoplasmic composition were determined with electron probe analysis in freeze-dried guinea pig aortic smooth muscle cells cultured on stainless steel grids. The mitochondrial calcium content in normal cells was low: not significantly different from that detected in the cytoplasm. Mitochondrial calcium granules were found in less than 3% of the cells, and in these the cytoplasmic K/Na ratio was reduced, indicating that they were damaged. There were no major differences between the cytoplasmic concentrations of K, Cl, Ca, Mg, and S of cultured cells and those previously found in adult vascular smooth muscle (Somlyo et al '79). There was no evidence of nuclear Na or Ca sequestration in cultured cells, and the transmitochondrial Na, Cl, and K gradients were small. Attempts to selectively remove adhering, extracellular ions with a 2-second wash with isotonic ammonium acetate were unsuccessful because they were accompanied by loss of cell K.

Animals↗
PubMed1989

Biological oxidation and the mobilization of mitochondrial calcium during the differentiation of Physarum polycephalum.

We have previously reported that calcium is required for the starvation-induced differentiation of the slime mold, Physarum polycephalum. With the exception of calcium, each component of the complex starvation medium may be withheld and the organism will still differentiate into spherules. The results of the present study reveal that spherulation will proceed normally when the microplasmoidal cells are transferred from nutrient medium to a citrate buffer containing only 8 mM CaCl2. Electron microscopy and X-ray microprobe analysis reveal that there is an initial increase in the population of calcium-containing mitochondrial granules when the microplasmodia are induced to differentiate. However, as differentiation proceeds, these granules decrease in number and are virtually absent from the mitochondria of mature spherules. The accumulation and depletion of calcium-containing granules is not observed in a nondifferentiating strain of Physarum cultured under standard conditions, but is observed when this strain is first treated with a calcium-enriched nutrient medium that conditions it for spherulation. Changes in the cellular concentrations of NADH and lipid peroxides, and in the activity of superoxide dismutase, correspond temporally to the pattern of increase and depletion of the calcium-containing inclusions. The oxidative stress associated with starvation-induced spherulation may be a consequence of the active accumulation of calcium; the mobilization of this calcium may then be the event that initiates differentiation.

Animals↗
PubMed1991

Grain boundary character distributions in Ni-16Cr-9Fe using selected area channeling patterns: methodology and results.

Selected area channeling patterns imaged on an SEM are digitized and displayed on the screen of a Macintosh computer, on which the user selects channeling bands that are measured to determine orientation. Grain boundary misorientations are found using the orientation information for pairs of grains adjacent at grain boundaries, and the boundaries are classified as low angle boundaries (LABs), coincident site lattice boundaries (CSLBs), or general boundaries (GHABs) based on the misorientation information. The technique was implemented to analyze the grain boundary character distributions (GBCDs) in Ni-16Cr-9Fe. The GBCDs of solution annealed material were similar to those expected in an aggregate of randomly oriented polycrystals. However, sequential thermomechanical treatments (5% tensile strain + 945 degrees C:75 min + 2% tensile strain + 890 degrees C:15 h + 3% tensile strain + 890 degrees C:20 h or 9% compressive strain + 890 degrees C:20 h + 9% compressive strain + 890 degrees C:20 h + 3% compressive strain + 890 degrees C:15 h) applied after the solution anneal lowered the proportions of GHABs in the GBCDs from 76-79% to 47-64%. The CSL-enhanced GBCDs of both the tensile-deformed samples and the compression-deformed sample appear to have evolved mainly through impingement of twin and twin-related boundaries during recrystallization; the CSL-enhanced GBCD of a compression-deformed sample appears to have been influenced by grain rotation processes to a greater degree than were the tensile-deformed samples The CSL boundaries in the CSL-enhanced GBCDs were, in general, closer to the exact CSL misorientations than were those in the near-random GBCDs of the solution annealed material. An analysis of the distribution of misorientation axes did not indicate any correlation between grain misorientation texture and GBCD evolution.

Alloys↗
PubMed1990

Theophylline tablets coated with aqueous latexes containing dispersed pore formers.

Constant drug release was achieved from theophylline tablets coated with a multiporous membrane in an aqueous environment. The tablets were coated with an aqueous acrylic latex containing a dispersed pore-forming agent with pH-dependent solubility characteristics. The pore former, dibasic calcium phosphate, was insoluble in the latex but leached out rapidly in 0.1 M HCl. Theophylline was then released at a constant rate through the multiporous membrane. The drug release was a function of the level of the pore-forming agent and the membrane thickness, but independent of the pH of the dissolution medium and the degree of agitation.

Chemistry, Pharmaceutical↗
PubMed2007

A novel method for the study of the biophysical interface in soils using nano-scale secondary ion mass spectrometry.

The spatial location of microorganisms and their activity within the soil matrix have major impacts on biological processes such as nutrient cycling. However, characterizing the biophysical interface in soils is hampered by a lack of techniques at relevant scales. A novel method for studying the distribution of microorganisms that have incorporated isotopically labelled substrate ('active' microorganisms) in relation to the soil microbial habitat is provided by nano-scale secondary ion mass spectrometry (NanoSIMS). Pseudomonas fluorescens are ubiquitous in soil and were therefore used as a model for 'active' microorganisms in soil. Batch cultures (NCTC 10038) were grown in a minimal salt medium containing 15N-ammonium sulphate (15/14N ratio of 1.174), added to quartz-based white sand or soil (coarse textured sand), embedded in Araldite 502 resin and sectioned for NanoSIMS analysis. The 15N-enriched P. fluorescens could be identified within the soil structure, demonstrating that the NanoSIMS technique enables the study of spatial location of microbial activity in relation to the heterogeneous soil matrix. This technique is complementary to the existing techniques of digital imaging analysis of soil thin sections and scanning electron microscopy. Together with advanced computer-aided tomography of soils and mathematical modelling of soil heterogeneity, NanoSIMS may be a powerful tool for studying physical and biological interactions, thereby furthering our understanding of the biophysical interface in soils.

Electron Probe Microanalysis↗
PubMed1990

An electron microscopic and electron probe study of the microcirculation in cold-induced oedema.

An ultrastructural study of adult mongrel dogs and cats was made to evaluate the changes in the microcirculation during cerebral oedema formation. Two to five cold injuries were made in one hemisphere in dogs and one lesion was made in cats. In several dogs arterial hypertension was induced with a balloon in the aorta. Intracranial pressure (ICP) and water content were measured. The specimens from the oedematous region were studied with transmission electron microscopy (TEM) and electron probe x-ray micro-analysis (EPMA). The TEM data showed swelling of the endothelium and astrocytic foot processes, enlarged perivascular spaces and increased number of endothelial vesicles. The EPMA findings indicated increases in Fe and Ca content in the perivascular spaces. In some cases, the amount of chloride in red cells was increased. The altered distributions of these metals suggested tissue injury and impairment of red cell and vessel wall functions.

Animals↗
PubMed1995

Energy-dispersive X-ray analysis of the extracellular cadmium sulfide crystallites of Klebsiella aerogenes.

Klebsiella aerogenes forms electron-dense particles on the cell surface in response to the presence of cadmium ions in the growth medium. These particles ranged from 20 to 200 nm in size, and quantitative energy dispersive X-ray analysis established that they comprise cadmium and sulfur in a 1:1 ratio. This observation leads to the conclusion that the particles are cadmium sulfide crystallites. A combination of atomic absorption spectroscopy, inductively coupled plasma mass spectrometry, and acid-labile sulfide analysis revealed that the total intracellular and bound extracellular cadmium:sulfur ratio is also 1:1, which suggests tha the bulk of the cadmium is fixed as extracellular cadmium sulfide. The tolerance of K. aerogenes to cadmium ions and the formation of the cadmium sulfide crystallites were dependent on the buffer composition of the growth medium. The addition of cadmium ions to phosphate-buffered media resulted in cadmium phosphate precipitates that remove the potentially toxic cadmium ions from the growth medium. Electron-dense particles formed on the surfaces of bacteria grown under these conditions were a combination of cadmium sulfide and cadmium phosphates. The specific bacterial growth rate in the exponential phase of batch cultures was not affected by up to 2mM cadmium in Tricine-buffered medium, but formation of cadmium sulfide crystallites was maximal during the stationary phase of batch culture. Cadmium tolerance was much lower (10 to 150 microM) in growth media buffered with Tris, Bistris propane, Bes, Tes, or Hepes. These results illustrate the importance of considering medium composition when comparing levels of bacterial cadmium tolerance.

Cadmium↗
PubMed1986

Ultracytochemical localization and microprobe quantitation of calcium stores in the insect oocyte.

Detection of calcium in the follicles of Galleria mellonella (Lepidoptera) was performed using two cytochemical methods. Calcium precipitation was obtained either with ammonium oxalate (AO) or with N,N-naphtaloylhydroxylamine (NHA). In both cases the X-ray "on line" analysis monitored the presence of calcium in the oocytes, which was correlated with the accumulation of yolk spheres. Concentration of calcium in oocytes filled with yolk and treated with AO amounted to 9 mmoles per 1,000 g tissue wet weight. This value is similar to that calculated previously for follicles untreated with any reagent and prepared for the analysis by the freeze-drying technique (Przeļecka et al. 1980). Examination of the ultrastructure of oocytes treated with NHA revealed calcium precipitate at the follicular epithelium/oocyte interface, in endocytotic canaliculi and vesicles formed by the oocyte plasma membrane, in ooplasm, and in yolk spheres. In oocytes treated with AO, the calcium-precipitate intermingled with the precipitate produced by the osmium alone. The presumed cause of this phenomenon is discussed.

Animals↗
PubMed1978

Histochemical and electron probe analysis of secretory ameloblasts of developing rat molar teeth.

Calcium was not found in secretory ameloblasts and stratum intermedium cells when treated with OsO4-pyroantimonate or when surfaces prepared by fracturing fresh, rapidly frozen, developing molar tooth germs were subject to electron probe X-ray analysis. Pyroantimonate reaction product, considered to be calcium, was found in mitochondria of enamel organ cells which were first placed in a bath containing calcium and potassium. The plasma membrane was disrupted in cells ehich showed mitochondrial localization of reaction product. The results provide no data which indicates that enamel organ cells have a direct, active role in the movement of calcium into the enamel. Rather, it is suggested that the secretory enamel organ might serve as a selective barrier in regulating the initial mineralization of enamel.

Ameloblasts↗
PubMed1982

Enzymic heterogeneity of adrenocortical lysosomes: an X-ray microanalytical study.

The enzymic heterogeneity of the lysosomal system has been demonstrated earlier. This study was concerned whether or not the lysosomes of the two outer zones of the rat adrenal cortex reveal any population characteristics on the basis of the activity of two enzymes. A double incubation method was used for the simultaneous electron cytochemical demonstration of acid phosphatase and arylsulphatase activity in the zonae glomerulosa and fasciculata of the adrenal. Lysosomes in semi-thin (0.5 micrometer) or ultra-thin sections were analysed with an ORTEC energy-dispersive X-ray microanalyser mounted on a JEOL TEMSCAN-100C electron microscope. Linearity of the amount of reaction deposit with incubation time was found for both enzymes. On the basis of the proportion of the two reaction products in individual lysosomes, three populations were distinguished. One with high acid-phosphatase and low, if any, arylsulphatase activity was only present in the zona glomerulosa. The other two populations exhibited stronger or weaker prevalence of arylsulphatase activity and were common in both zones. The values of the Ba/Pb ratio characteristic of each population changed with the reaction sequence but the principal distribution pattern did not. The nature of the interaction between the two reactions, as well as the possible functional significance of the lysosomal populations in the adrenal cortex, are discussed but are not yet clarified.

Acid Phosphatase↗
PubMed1986

Extensive subretinal pigment epithelial deposit in two brothers suffering from dominant retinitis pigmentosa. A histopathological study.

The eyes of two brothers with retinitis pigmentosa were removed after death and examined by a variety of techniques, including conventional histology, fluorescence microscopy and both scanning and transmission electron microscopy. Their condition was considered to be of an autosomal dominant type but with some atypical clinical features. The outstanding histological feature in both pairs of eyes was a predominantly acellular deposit of amorphous material situated between the retinal pigment epithelium and Bruch's membrane. This material extended from the disc to beyond the ora serrata. In some regions of the retinae of both brothers, there was a cellular infiltrate into the deposit and this included multinucleate cells. In one brother the deposit was lined externally by a fibrovascular membrane in some few locations. All retinae were degenerate, but all showed preservation of abnormally short and sparse photoreceptor cells in both the peripheral and macular areas. There was only patchy loss of the choriocapillaris, which could have been age-dependent rather than disease-dependent, and the remaining choroidal vessels were patent in all cases. The widespread distribution of the deposit is unusual and suggests that it arises from disordered metabolism of the retinal pigment epithelium. We could not determine whether it was a primary disease process or if it arose as a secondary phenomenon.

Electron Probe Microanalysis↗
PubMed1995

Accumulation of hydroxyapatite in the kidney of streptozotocin-induced diabetic rat fed a low-zinc diet.

Calcification occurred in the kidney of streptozotocin (STZ)-induced diabetic rats fed a low-zinc diet. The deposits were stained by the von Kossa method and were detected intracellularly in the tubular cells, mainly in the cortico-medullar region. The deposits were found to be a heterogenous substance on electron microscopy. There were various sizes of deposits, and the surfactant was very much distorted. Many deposits grew up to bind small particles, and the core-like substance was observed in the center of the deposit. The component of the deposit was analyzed by an X-ray microanalyzer, and was found to be calcium and phosphorus. The ratio of calcium to phosphorus was 2.159, which coincided with the ratio of standard hydroxyapatite. From these observations, the deposit is believed to be hydroxyapatite. It is thought that the core is formed at first, many particles are then bound to the core, and deposits grow up.

Animals↗
PubMed2004

Qualitative and quantitative determination of micro-inclusions by automated SEM/EDX analysis.

With the help of an automated SEM/EDX analysis system non-metallic micro-inclusions in steel can be detected on a metallographically prepared surface area. The system makes it possible to determine position, size, shape and composition of each particle. Usually more than 1000 inclusions are found on one scan area. Therefore a new offline evaluation method has been developed to classify the large amount of inclusions and calculate specific size and shape data. A summary sheet is created to show the area contents and the mean values of all important properties for each class. Size and XY distributions as well as binary and ternary phase diagrams are drawn to depict the results. The strengths of this analytical technique are demonstrated by evaluation of an LC (low-carbon) steel. Alumina, common spinel, sulfide and oxisulfide inclusions could be identified as dominant inclusion types in LC steel.

Electron Probe Microanalysis↗