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Results for “Electron Probe Microanalysis”

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PubMed1989

Detoxification of cadmium. Ultrastructural study and electron-probe microanalysis of the midgut in a cadmium-resistant strain of Drosophila melanogaster.

The midgut of a cadmium-resistant strain of Drosophila melanogaster has been studied at the ultrastructural level and by electron-probe microanalysis (EPMA). Chronic exposure to cadmium leads to a concentration of the metal in a lysosomal system developed in both anterior and posterior segments of the midgut, where it coexists with copper and sulfur. This mechanism apparently ensures a permanent cadmium detoxification and prevents cellular injury. Wild-type flies fed on a cadmium-contaminated medium manifest the same detoxification process. As a result of contamination, copper is stored along the entire length of the midgut, including a part of the middle-midgut previously named 'copper-accumulating region'. Our data demonstrate that the midgut, particularly the posterior segment, is an accumulative organ for both cadmium and copper. The involvement of the metallothionein system in the detoxification process is discussed.

Animals↗
PubMed1977

Electron probe microanalysis of the chemical elemental content of human follicular fluid.

Follicular fluid samples were obtained by puncturing follicles of ovaries in situ from patients undergoing laparotomy. Sodium, potassium, chloride, magnesium, calcium, phosphorus, and sulfur concentrations measured by electron probe microanalysis were similar to those of blood, with minimal differences. This suggested that culture media in which these electrolytes are added in concentrations similar to those of serum are appropriate for culture of the human oocyte.

Calcium↗
PubMed1988

Localization of cations by pyroantimonate. II. Electron probe microanalysis of calcium and sodium in skeletal muscle of mouse.

A new formulation of the pyroantimonate (PA) method for localization of calcium and sodium is proposed and evaluated in mouse skeletal muscle. This study, performed at the ultrastructural level by means of transmission electron microscopy (TEM) and electron probe microanalysis (EPMA), completes a previous work done at the optical level with analytical ion microscopy (AIM), which enabled us to define the appropriate composition of fixatives. In our present experiments, calcium and sodium were shown localized in various cell structures, e.g., T-tubules, glycogen, granules, nuclei. For AIM, the best fixatives were characterized by PA supersaturation, which resulted in smaller crystals and a high rate of penetration in the presence of paraformaldehyde and either phenol or collidine. Contrary to the findings at the optical level, collidine did not give satisfactory results at the ultrastructural level. The method of floating sections on the microtome trough was an important cause of cation displacement. We found that alkalinization of the floating medium significantly decreased ion loss. The technique also provided an indication of the form of these elements: free or easily liberated cations were precipitated into coarse PA deposits; electron-positive chelates were "stained" by PA; neutral chelates were not stained, but some of them could be detected by EPMA. This PA method should make possible more precise localization of cellular calcium, such as in glycogen metabolism, and perhaps detection of movements of cytoplasmic calcium and sodium.

Animals↗
PubMed1978

Electron probe microanalysis of red blood cells. II. Cation changes during maturation.

To understand the sequence of maturation of membrane transport and hemoglobin production during erythropoiesis, we have measured the K, Na, and Fe content in single mature red blood cells and bone marrow cells of dog using electron probe microanalysis (EPMA). Mature red blood cells of dog are low in potassium (LK) and high in sodium. These cells are derived from erythroblastic stem cells, which are high in potassium (HK) and low in sodium. This change from HK stem cells to LK red cells occurs in the marrow. The ratio of K/Na was found to be less than 0.2 independent of Fe/(K + Na) in circulating red cells. However, a significant number of marrow cells had both low K/Na and low Fe/(K + Na). We conclude that the changes in cation transport properties responsible for the conversion of HK to LK cells occur before the synthesis of hemoglobin in at least some marrow cells.

Animals↗
PubMed1991

Large and rapid changes of myofibrillar total calcium during the cardiac cycle. Electron probe microanalysis of voltage-clamped guinea-pig ventricular myocytes.

At 36 degrees C and 2 mM [Ca2+]o, single guinea-pig ventricular myocytes were voltage clamped with patch electrodes. When paired pulsing had potentiated the contraction to the maximum, the cells were shock-frozen for electron probe microanalysis (EPMA). Shock-freezing was timed at the end of diastole (-80 mV) or at different times during systole (+5 mV). The same paired-pulse protocol was applied to another group of myocytes from which contraction was recorded and [Ca2+]i was estimated by microfluospectroscopy (50 microMNa-Indo-1). In potentiated cells, during the first pulse, contraction peaked within 128 +/- 25 ms after start of depolarization. [Ca2+]i peaked within 25 ms to 890 /+- 220 nM (mean +/- SEM) and fell within 100 ms to about 450 nM. sigma Camyo, the total calcium concentration in the overlapping myofilaments (A-band), was measured by EPMA in 17 potentiated myocytes. During diastole, sigma Camyo was 2.6 +/- 0.4 mmol/kg dry weight (dw), which can be converted to 0.65 mM (mmoles per liter myofibrillar space). Since [Ca2+]i was 180 nM, we estimate that 99.97% of total calcium is bound. A time-course for systolic sigma Camyo was determined by shock-freezing 13 cells at different times after start of depolarization to +5 mV. sigma Camyo was 5.5 +/- 0.3 mmol/kg dw (1.4 mM) after 15-25 ms, 4.6 +/- 0.5 mmol/kg dw (1.1 mM) after 30-45 ms, and 3.1 mmol/kg dw (0.8 mM) after 60-120 ms. The fast time-course of sigma Camyo suggests that calcium binds to and unbinds from troponin C at a fast rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1977

Electron probe microanalysis in the study of gallstones.

Detailed information on the structure and composition of gallstones was obtained using an electron probe microanalyser in conjunction with the other methods. Gallstones were studied layer by layer without greatly disturbing the arrangement of the materials present. Elements, including trace elements such as copper, iron, and manganese, were identified and their distributions mapped. The range of the method was extended to determine the character and distribution of certain chemical groups present by treating sections of gallstone with reagents which contained easily detected elements. The nature of the bonding of the sulphur in the stones was studied by examining the sulphur-X-ray spectrum. Pigmented sulphur-containing deposits were found to contain sulphur in a low valence state but taurine conjugates and the sulphate groups of mucosubstances were not detected. Microcrystalline apatite present in the stones contained some manganese and seemed to be implicated in the absorption of the low valence sulphur compound and in the nucleation of some stones.

Calcium↗
PubMed1977

Identification of stainless steel welding fume particulates in human lung and environmental samples using electron probe microanalysis.

Open lung biopsy specimens from two welders and air samples from their workplace environments were examined with the electron probe microanalyzer. X-ray analysis showed that the majority of particles found in the lung tissue from both workers and in the air samples to be composed of varying amounts of iron, chromium, manganese and nickel, the major components of some types of stainless steel. Based upon these analyses, it was concluded that the majority of the particles in both biopsy specimens were a result of the workplace environment.

Air Pollutants, Occupational↗
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↗
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↗