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PubMed1992

Electron probe microanalysis of the otolithic membrane. A methodological and quantitative study.

The effect of tissue preparation on calcium and potassium weight percent in the otoconial layer in the utricle and saccule was studied in four groups of OF1 mice with electron probe X-ray microanalysis. Glutaraldehyde and freeze-drying, glutaraldehyde and air-drying, air-drying, and cryo-fixation and freeze-drying were compared. Ca and K changed significantly in the utricle depending on the method used (P < 0.001), and K changed significantly in the saccule (P < 0.001). We chose cryo-fixation with freeze-drying for the quantitative analysis of the otolithic membrane because this method provided the highest values of Ca and K with minimum loss of Ca and K. Microcrystalline salt standards mounted on scanning electron microscopy holders were used for the quantification of Ca and K by the peak-to-local-background (P/B) ratio method. The P/B ratio in standards with reproducible results, when plotted against weight percent, gave a straight line for Ca (r = 0.99, P < 0.001) and K (r = 0.98, P < 0.001). The Ca and K weight percent in otoconia showed similar frequency distributions in the utricle and saccule.

Animals↗
PubMed1994

Electron probe microanalysis of gentamicin-induced changes on ionic composition of the vestibular gelatinous membrane.

Gentamicin-induced changes in ionic composition in the otolithic membrane of adult OF1 mice were evaluated in the gelatinous layers of the saccule and utricle by quantitative electron probe X-ray microanalysis. The otolithic membranes were plunge-frozen and freeze-dried to prevent the redistribution of elements. Quantitative analysis was carried out with an energy dispersive detector using the peak-to-background (P/B) ratio method and different salts dissolved in dextran as standards to calibrate the P/B ratio against the concentration of the elements P, S and K in the microprobe. Gentamicin selectively decreased the concentrations of P (P < 0.001) and S (P < 0.01) in the gelatinous membrane of the saccule, and had no effect in the utricle. The concentration of K also increased in the utricular gelatinous membrane (P < 0.05). The mechanism of ototoxicity in the gelatinous membrane is unknown, but the ability of aminoglycosides to block calcium channels may induce disturbances in the ionic equilibrium of the endolymphatic fluid, and thus affect the biochemical composition of the gelatinous membrane. This technique can be useful to evaluate the distribution of ions in the process of drug-induced ototoxicity.

Animals↗
PubMed1979

Electron probe microanalysis of elemental composition of mouse cardiac myocytes during post-natal maturation.

Elemental concentrations in the cytoplasm and nucleus of t tests post-natal mouse myocytes were measured at 2, 4, 8, 16, 32 days and in adults using electron probe X-ray microanalysis. Using an analysis of variance test, significant age dependent changes were found in intracellular potassium, sulfur, phosphorus, and chlorine concentrations (mg/kg dry weight), while sodium and magnesium concentrations did not show significant changes. The application of t tests following linear regression analyses (age versus concentration for each element) did, however, give a significant slope for cytoplasmic sodium, potassium, sulfur, and phosphorus values. The findings correspond closely with an emission spectroscopy-titrimetric study of whole heart ventricle of the same developmental period (Hazelwood and Nichols, '70).

Aging↗
PubMed1991

Electron probe microanalysis of calcium release and magnesium uptake by endoplasmic reticulum in bee photoreceptors.

Honey bee photoreceptors contain large sacs of endoplasmic reticulum (ER) that can be located unequivocally in freeze-dried cryosections. The elemental composition of the ER was determined by electron probe x-ray microanalysis and was visualized in high-resolution x-ray maps. In the ER of dark-adapted photoreceptors, the Ca concentration was 47.5 +/- 1.1 mmol/kg (dry weight) (mean +/- SEM). During a 3-sec nonsaturating light stimulus, approximately 50% of the Ca content was released from the ER. Light stimulation also caused a highly significant increase in the Mg content of the ER; the ratio of Mg uptake to Ca released was approximately 0.7. Our results show unambiguously that the ER is the source of Ca2+ release during cell stimulation and suggest that Mg2+ can nearly balance the charge movement of Ca2+.

Animals↗
PubMed1989

[Comparative study of bioactive calcium phosphate ceramics after implantation in spongy bone in dogs. Histologic, ultrastructural and electron probe microanalysis].

An experimental model of posterior spine arthrodesis in dogs was created using 3 types of calcium phosphate biomaterials already known for their applications as bone substitutes, namely: hydroxyapatite (HA), which is not readily resorbable; highly resorbable tricalcium phosphate (TCP); and a mixture of HA and TCP (BCP), the resorbability of which depends on the proportion of HA and TCP. The BCP implants had a macroporous structure, whilst the HA and TCP implants were used in dense form. The creation of macropores increases the surface exchange area, thus enabling the osseous colonization processes. By carefully removing the posterior articular facets it was possible to remove the articular surfaces and to fit into each appropriate location a block a few millimeters in diameter. The anatomopathological assessment was performed using histological methods, transmission electron microscopy, and energy dispersion microprobe analysis. Our results indicate that calcium phosphate ceramics may be used as bone substitutes for carrying out arthrodeses, provided (1) immediate immobilization using a spine containment technique is effected; (2) their chemical composition is sufficiently stable over time; (3) they are sufficiently bioactive so as to allow their colonization and replacement by bone.

Animals↗
PubMed1980

Electron-probe microanalysis. Aid in the study of skin granulomas.

Several causes of noncaseating epithelioid granulomas of the skin must be considered before the diagnosis of sarcoidosis can be made. We report here three such cases that were studied retrospectively with scanning electron microscopy in combination with backscattered electron imaging and x-ray energy spectrometry. Inorganic particles were identified in the granulomas of two patients, illustrating that these techniques are valuable aids in establishing the cause of granulomas.

Adult↗
PubMed1993

Strontium, a tracer to study the transport of calcium in mineralizing tissues by electron probe microanalysis.

In growth plate cartilage the mineralization starts extracellularly in the lower hypertrophic zone. The mineral formed is the calcium phosphate apatite. Enough calcium and phosphate must be available at the mineralization front as well as in regions with proceeding mineralization. There must be a transport of Ca (and phosphate) to these sites. Electron probe X-ray microanalysis is a well established method to analyze element concentrations in small volumes, but it cannot discriminate isotopes. Strontium is similar to Ca in its chemical and biological behaviour and is therefore a suitable tracer to investigate the transport of Ca. Small amounts of Sr (0.1 g per kg body weight) were administered intraperitoneally to young rats. After definite intervals of time ranging from 10 to 120 min, 2-4 rats were killed. On freeze dried cryosections the Sr/Ca ratio of the serum and of the intra- and extracellular space of the growth plate were measured. The Sr/Ca ratio reaches its maximum after about 10 min in the serum and after 20 min in the extracellular space of growth plate cartilage. The intracellular Sr/Ca ratio shows large variations because of the low intracellular Ca and Sr concentration, and is lower than the extracellular ratio for times shorter than 30 min. No significant differences were found between the different cell zones of the unmineralized growth plate cartilage. The results demonstrate that the transport of Ca to the growth plate cartilage is relatively fast and that in growth plate cartilage, Ca is transported extracellularly, not intracellularly.

Animals↗
PubMed1993

[Corrosive changes of dental alloys in oral environment--scanning electron microscopic observation and electron probe microanalysis on crown surfaces].

In order to study the changes of the intraoral metals, the surface condition and composition of the crowns removed from mouths were analyzed by SEM and EPMA. Thirty-four samples were categorized into four types of alloys. Corrosive changes were evaluated by comparing the analysis results between the crown surface and its fresh sectioned surface, and also with the data from former studies. 1. Changes observed in the Au alloys were slight compared to the other three types, both in surface feature and composition, except for a slight decrease in Cu. 2. In some Au-Ag-Pd alloys, nearly no dissolution was evident. Composition changes were small, with a slight decrease in Ag and relative increase in Pd. 3. The greatest changes were observed in the Ag-Sn-Zn alloys and Ag-In alloys, even with short intraoral usage period. Generally, their surfaces were rough, with thick layers of organic materials. The dendritic structure was distinct, and dissolution between each dendrite was observed. 4. Many of the Ni-Cr alloys presented dendritic structure with dissolution. Decrease in Ni and relative increase in Si and Cr were observed. 5. Corrosive changes showed a close resemblance to the results obtained by the conventional basic tests. However, there were some features which did not coincide, depending on the types of alloys.

Corrosion↗
PubMed1980

Cryoultramicrotomy, electron probe microanalysis and STEM of myocardial tissue.

Heart muscle preparations (papillary muscles and trabeculae) were frozen at 4.2 K on metal plate under vaccum after their length-tension relationships showed that no damage had occurred during dissecting and mounting the strips on the holder. Freeze substitution of some preparations directly after freezing demonstrated that no important cell damage due to ice crystals occurred in superficial cell layers during freezing. Ultrathin cryosections obtained at -130 degrees C were freeze dried and analyzed, in the STEM mode. The better the freezing procedure, the poorer was the contrast of the sections under electron microscopy. Preliminary approaches to increasing contrast after sublimation of tissue water show that a small increase in contrast is generally obtained at the cost of the peak/background ratio due to pronounced mass loss. The results of our analyses show that C1 content in heart muscle cells is high and distributed throughout the cytoplasm. Ca is detectable and quantitable in resting muscle in SR cisternae. The Ca amount in cytoplasm is low and just at the limit of detectability under our current analysis conditions. Preliminary experiments on papillary muscles subjected to caffeine contracture showed that calcium is not detectable in the cisternae as is the case in control experiments. Only a moderate amount of Ca is detectable in mitochondria, whereas the concentrations in cytoplasm, as in resting cardiac muscle, is too low to be quantitated.

Animals↗