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 91 records · Page 5Linked to original sources
PubMed1978

Electron probe microanalysis of red blood cells. I. Methods and evaluation.

The concentrations of potassium, sodium, and iron in human and sheep red blood cells were measured with an electron probe. Cells were prepared for analysis by spraying them on pyrolytic graphite supports. The results obtained with this spray technique agreed well with values measured on similar cells that were prepared for analysis by freezing, sectioning, and freeze-drying. Higher Na concentrations and lower K concentrations were found to be associated with lower cell volumes in human and high-potassium sheep cells. In low-potassium sheep cells the reverse was found, lower Na and higher K concentrations were associated with lower cell volumes. However, the amounts of iron were found to remain relatively constant in all human cells.

Cell Membrane Permeability↗
PubMed1969

The distribution of the water-soluble inorganic orthophosphate ions within the cell: accumulation in the nucleus. Electron probe microanalysis.

Lead acetate treatment of unfixed cells immobilizes the intracellular water-soluble, inorganic orthophosphate ions as microcrystalline lead hydroxyapatite precipitates (see reference 1). These precipitates have been analyzed with the electron microprobe. A much higher concentration of phosphorus has been found in the nucleoli of maize root tip cells fixed in lead acetate-glutaraldehyde (organic phosphorus plus inorganic orthophosphate), as compared to the nucleoli of roots fixed in glutaraldehyde alone (organic phosphorus). The concentration of the inorganic orthophosphate pool in these nucleoli is three to five times as high as the concentration of the macromolecular organic phosphate. Since nearly all of the latter is in RNA, the concentration of inorganic phosphate in the nucleolus is calculated to be roughly 0.5-0.8 M. About 30%-and up to 50%-of the total cellular inorganic phosphate is accumulated in the nucleolus since the mean concentration per cell is about 10(-2)M. In the extranucleolar part of the nucleus the mean concentration was estimated by densitometry to be roughly six times less than in the nucleolus ( 0.1 M), and appears more concentrated in the nucleoplasm than in the condensed chromatin. While there is no direct evidence for the concentration in the cytoplasm, it certainly must be much lower than the mean cellular level (i.e., < 10(-2)M) since the nucleus is about 10% of the total cell volume. The implications of this compartmentation in the intact cell are discussed in connection with (A) the availability of orthophosphate ions for the cytoplasm in those processes in which these ions affect the rate of enzymatic reactions, and (B) protein nucleic acid interactions within the nucleus and nucleolus.

Cell Nucleolus↗
PubMed1991

Line analysis of interface layer on dentin by means of electron-probe microanalysis.

Three types of brominated methacrylates, SBPPM, BPylM, and BNEM, were synthesized. The distribution of Br, Ca, and Fe at the interface between dentin treated with the 10-3 solution and resin containing these monomers was analyzed using an electron-probe microanalyzer (EPMA) in order to predict the composition and thickness of the interface layer on dentin for the corresponding unbrominated methacrylates. There was no significant difference between the brominated and unbrominated methacrylates in either the bond strength to the treated dentin or in the thickness of the interface layer on dentin observed with a scanning electron microscope (SEM). The thickness determined with EPMA was equivalent to that observed with SEM. The concentration of each brominated methacrylate in the interface layer was higher than the original concentration in the resin monomers, and BNEM showed higher concentration than the others. The presence of Fe in the layer was confirmed by EPMA.

Animals↗
PubMed1990

[Electron-probe microanalysis examination of acid-proof dentin layer].

To predict the presence and thickness of the acid-proof dentin layer by the method of combining the halogenated methacrylate and electron-probe microanalyzer (EPMA), 2-methacryloyloxyethyl hydrogen chloromaleate (CIMEM) used as a base monomer for a bonding agent and 2-bromoethyl methacrylate (2 BEM), 2-(4-bromophenyl)ethyl methacrylate (BPy1EM), 2-(4-bromo-1-naphthyl)ethyl methacrylate (BNEM) and 2,4,6-tribromophenoxy methacrylate (TriBr-PM) used as tracers were synthesized. The bond strength to dentin treated with 37% phosphoric acid solution for 30 sec. was not statistically different for the bonding agents with and without tracers. The SEM micrographs revealed that the layers, which may be acid-proof dentin layers, were 3-4 microns thick at the resin-dentin interface for all bonding agents. According to EPMA analysis, cps of C1Ka and BrLa increase at the same points and the acid-proof dentin layer thickness was about 4 microns.

Acid Etching, Dental↗
PubMed1975

Evaluation of silicon and germanium retention in rat tissues and diatoms during cell and organelle preparation for electron probe microanalysis.

Chemical, radiochemical and x-ray microanalysis assays were used to define parameters of silicon (Si) retention during preparation og biologic samples (rat liver, spleen, kidney, lung, diatoms and cell organelles) for x-ray microanalysis, Due to its longer half-life 68-Fe was used in some cases to trace SI. Leaching of Si from cells and organelles by the aqueous preparation media was overcome by use of the freeze-substitution process. Cells were treated with 30% glycerol hypertonic sucrose medium to reduce ice damage. Embedment in Spurr's low viscosity epoxy resin medium caused no apparent Si loss. A semiquantitative evaluation showed 0.5 x 10-8 to 0.3 x 10-17 g detectable Si in isolated rat liver mitochondria in thin sections, which is within the instrument's range of detection. This study indicateds that the presence of Si in the mitochondria is not the rsult of contamination.

Animals↗
PubMed1988

Electron probe microanalysis of the subcellular compartments of bovine adrenal chromaffin cells. Comparison of chromaffin granules in situ and in vitro.

The elemental and water content of cultured bovine adrenal chromaffin cells and their secretory chromaffin granules have been measured and compared with isolated chromaffin granules using quick freezing, ultracryomicrotomy, and electron microprobe analysis methods. In units of millimole/kilogram dry weight (+/- S.E.) granules in situ contained: P, 523 +/- 32; K+, 124 +/- 9; S, 82 +/- 3; Cl-, 74 +/- 9; Ca2+, 13 +/- 2; Mg2+, 6 +/- 2; and Na+, -2 +/- 2. Following routine isolation in isotonic sucrose buffer, granule K and Cl- had decreased while granule Na+ increased. Cl- exhibited a consistent decrease to 35-40 mmol/kg dry weight. Granule Na+ and K+ concentrations ranged from 43 to 12 mmol/kg and 28 to 60 mmol/kg dry weight, respectively, depending on the Na+ and K+ content of the buffer. Despite the redistribution of monovalent ions, granule Ca2+, granule P, being in the form of ATP, and granule S, being in the form of protein, were not significantly changed. The stability of these elements is consistent with the existence of a stable storage complex for Ca2+, ATP, and protein. Using the granule as an internal standard with a water content of 66%, the water contents of external space, nucleus, cytoplasm, and mitochondria were estimated to be 89, 88, 82, and 70%, respectively. Wet weight concentrations for each element were calculated for granules and cytoplasm from which the transgranular concentration gradients for K+, Cl-, and Na+ were determined. Cl-, a permeant anion, was 2-fold higher in the granule than in the cytoplasm while K+, a slightly permeant cation, had an opposite distribution ratio slightly less than two. Together, the K+ and Cl- data suggest the presence of an inside-positive granule membrane potential of approximately 10-16 mV. The surprising lack of Na+ from the granule matrix suggests a hugh inward gradient for Na+ even though the Na+ content of chromaffin cell cytoplasm is low at 5 mmol/kg water. The lack of an outward Na+ gradient is important in that it indicates that the previously described electroneutral Na+-Ca2+ exchange system, by which isolated granules accumulate Ca2+, does not operate in mature granules in situ. Consequently, if chromaffin granules regulate internal calcium during stimulus secretion coupling, a mechanism other that Na+-Ca2+ exchange is necessary.

Adenosine Triphosphate↗
PubMed1977

Electron probe microanalysis of chemical elemental content of single human red cells.

Sodium, potassium, iron and sulfur contents of single human red cells were measured using electron microprobe microanalysis. Three preparative procedures were compared, and the most reliable technique was found to be spraying of cells onto polished pyrolytic graphite by atomization. Primary standards were prepared by adjusting the intracellular electrolyte content of red cells, eliminating the need to correct for X-ray absorption. Samples were stable under the electron beam during analysis, and could be stored for long periods of time. Strong correlations were found between the X-ray intensities of iron and sulfur and between potassium and sodium. X-ray intensities of potassium and sodium were found to be directly proportional to internal ionic content. Large populations of single cells could be analyzed and the distribution of their elemental content studied.

Electron Probe Microanalysis↗