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PubMed1998

[The changes in quantities of elements around cementum-dentin junction in human natural tooth--electron probe microanalysis].

To study the changes of inorganic and organic substance around cementum-dentin junction in the tissues of human natural tooth, the method of electron probe microanalysis was used in this research project. Determinations of weight percentage (wt%) were made for Ca, P and S elements around cementum-dentin junction. The results showed that the changes in quantities of Ca, P and S elements around cementum-dentin junction were not significant(P > 0.1). These suggest that the quantities of inorganic and organic substance have not obviously varied with the anatomic structure of natural tooth.

Adult↗
PubMed2006

Characterization of dentin formed in transplanted rat molars by electron probe microanalysis.

The present study was designed to characterize dentin formed in transplanted rat molars by investigating calcium (Ca), phosphorus (P), and magnesium (Mg) concentrations using electron probe microanalysis (EPMA) as well as examining the rate of dentin matrix formation by vital staining. The unerupted immature lower right second molar in 2-week-old rats was transplanted into the upper right first molar socket. Rats were injected with oxytetracycline, calcein, and alizarin intraperitoneally at 1 day before and 1 and 2 weeks after transplantation, respectively, for vital staining. The maxillae and mandibles were fixed 3 weeks after transplantation, resected, and embedded in resin. Undemineralized sections were cut and examined by fluorescent microscopy and EPMA. The thickness of dentin formed in the first week after transplantation was significantly less than that of dentin formed in any other 1-week period in the transplanted tooth and was about one-fifth the thickness of dentin formed in control teeth. Formation of dentin recovered in the third week after transplantation. In the first week after transplantation, EPMA demonstrated a sharp increase in Mg concentration with a slight decrease in Ca concentration. Thereafter, no significant difference was identified among Ca, P, or Mg concentrations or the Ca/P ratio between transplanted and control teeth. These results suggest that disruption of the circulation and innervation by transplantation cause a temporary change in the matrix formation rate and elemental distribution of dentin, which is subsequently restored within 2 weeks after transplantation.

Animals↗
PubMed1989

Application of the pyroantimonate method and electron probe microanalysis to the study of glycogen metabolism in liver.

Glycogen distribution in the liver of mouse under different metabolic conditions was studied by the pyroantimonate (PA) method combined with semi-quantitative electron probe microanalysis (EPMA). In the liver of animals subjected to a sugar-rich diet, glycogen granules were abundant and electron transparent. In fasted animals, they were less numerous and stained by PA, which indicates the presence of a complexed cation. This cation was identified as calcium by EPMA. In both cases, adjacent cytoplasmic areas contained "masked" calcium not revealed by PA but detected by EPMA, which is characteristic of a neutral complexed form; but in the case of the fasted animals, the calcium concentration was significantly lower. If the liver of fasted animals was dissected in 0.2% glucose-containing medium, the glycogen areas dramatically released calcium and lost their stainability by PA, whereas mitochondria and adjacent cytoplasm contained many PA precipitates rich in calcium and sodium, suggesting a sudden increase of intracellular [Ca2+]. In mitochondria, the sodium:calcium ratio was relatively constant, which suggests a process involving a coupling between these two elements. Our results could be explained in the light of physiological and biochemical data. We particularly noted that diffusible cations as calcium and sodium did not appear to be displaced over long distances from their likely source. This observation agrees with recent theories on the state of water and ion mobility in the cell.

Animals↗
PubMed1985

Titanium pigmentation. An electron probe microanalysis study.

A patient had an unusual pigmentary disease induced by titanium dioxide. The use of a topical cream containing titanium dioxide caused a xanthomalike appearance on the patient's penis. Electron probe microanalysis was valuable in establishing the cause of this balanitis.

Adult↗
PubMed1992

Comparison of cryopreparation techniques for electron probe microanalysis of cells as exemplified by human erythrocytes.

Erythrocytes in human blood were used to evaluate the reliability of cryopreparation techniques for electron probe X-ray microanalysis of biological cells and tissues. The elemental content determined by X-ray microanalysis of ultrathin freeze-dried cryosections was found to be consistent with data known from the literature. Considerable redistribution of the intracellular elemental composition was found after freeze-substitution as well as after freeze-drying followed by resin embedding. Two conclusions are drawn from this study: 1. Erythrocytes in human blood are a suitable reference specimen for evaluation of specimen preparation techniques for microanalysis. 2. At present, freeze-dried cryosections are the most reliable specimen type for quantitative electron probe microanalysis of cells.

Cryopreservation↗
PubMed1988

Earliest enamel deposits of the rat incisor examined by electron microscopy, electron diffraction, and electron probe microanalysis.

In order to describe initial events in enamel mineralization and to help characterize inorganic-organic interactions in this tissue, the earliest rod and interrod enamel in mandibular incisors from normal young adult (100 gm) rats, perfused with 100% ethylene glycol, has been studied by transmission electron microscopy, selected area electron diffraction, and high-spatial-resolution electron probe microanalysis. Diffraction and probe data were correlated precisely from the same extracellular regions of the tissue. Sites were examined progressively as a function of location a) from the most recently deposited enamel adjacent to ameloblasts toward the dentin-enamel junction and b) from the apical portion of the tooth longitudinally toward its incisal end. Electron diffraction patterns consistent with that of a poorly crystalline hydroxyapatite were generated at all locations. Diffraction characteristics changed only slightly toward that of more crystalline hydroxyapatite at different locations. Earliest apical enamel generated molar Ca/P ratios in a range of 0.99-1.46 (average 1.24 +/- 0.15). Molar Ca/P ratios of the first enamel interrod elements increased from approximately 1.24 at ameloblast-enamel boundaries to approximately 1.40 at the dentin-enamel junction, small changes corresponding to those observed in electron diffraction characteristics.

Animals↗
PubMed1983

Element analysis of Lewy and adrenal bodies in Parkinson's disease by electron probe microanalysis.

Two possible interpretations of the origin of Lewy bodies and adrenal bodies found in Parkinson's disease are now under discussion: a disorder of (1) catecholamine metabolism or (2) sphingomyelin lipidosis. From the electron probe microanalysis of Lewy bodies and adrenal bodies, we find that the Lewy body contains sulfur, calcium, and phosphorus, and the adrenal body also contains these three elements. Furthermore, a positive correlation was obtained between the X-ray intensity of the sulfur and the diameter of adrenal body. For Lewy bodies, this correlation was not obtained. The results suggest that a common mechanism may exist for the production of Lewy and adrenal bodies, although they differ somewhat in their accumulation of sulfur. It is considered that both structures may originate, in part, from degenerated protein containing sulfur.

Adrenal Glands↗
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↗
PubMed2005

Electron probe microanalysis of potassium and sodium in clonogenic culture of human neural stem cells.

The mean potassium and sodium concentrations and distribution of potassium in clonogenic culture of human neural stem cells (neurosphere) were estimated by means of electron probe microanalysis. High sodium concentration was typical of undifferentiated cells. Potassium was irregularly distributed in the test structure. Our results confirm published data on heterogeneous morphological structure of neurospheres.

Brain↗
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↗
PubMed1984

Localization of zinc in the thymic reticulum of mice by electron-probe microanalysis.

Thymulin, a thymic hormone, is a nonapeptide requiring zinc for biological activity. It has been shown that epithelial cells, forming part of the thymic reticulum, secrete this hormone and/or store it within cytoplasmic vacuoles. X-ray electron-probe microanalysis (EPMA) has been used to detect zinc in the thymus. Low concentrations of zinc have been demonstrated in the dense granules contained in clear vacuoles of some epithelial cells in normal and ZnCl2-injected mouse thymuses, thus suggesting that the metal may be coupled to the peptide before the secretion of the hormone from the cells.

Animals↗
PubMed1993

Calcium displacement by lanthanum in subcellular compartments of rat ventricular myocytes: characterisation by electron probe microanalysis.

OBJECTIVE: Much of the calcium in cardiac myocytes resides in a kinetic compartment defined by rapid exchange and rapid displacement by La3+. The aim of this study was to ascertain the subcellular location of this calcium pool. METHODS: Electron probe microanalysis (EPMA) was used to measure redistribution of total calcium in rat cardiac myocytes after 30 s in 1 mM lanthanum. "Cells", mitochondria, and myofibrils were separately analysed. The data permitted calculating a third (difference) compartment, containing primarily sarcoplasmic reticulum, sarcolemma, and T tubule lumen. Total calcium levels in junctional sarcoplasmic reticulum and T tubule lumen were also measured directly. RESULTS: Lanthanum decreased total "cell" calcium from 1.4 (SEM 0.3) to 0.5(0.4) mmol.kg-1 dry weight (p < 0.05); loss from the third (difference) compartment was primarily responsible. Simultaneously, junctional sarcoplasmic reticulum increased from 5.1(0.6) to 8.2(0.9) mmol.kg-1 dry weight (p < 0.05), while the T tubule lumen was unchanged. CONCLUSIONS: These results suggest that lanthanum displaced calcium primarily from sarcolemmal sites and that calcium redistributed to sarcoplasmic reticulum from an intracellular source.

Animals↗
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↗