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PubMed1983

Changes in elemental composition of single muscle fibers following tenotomy of the rat soleus muscle.

Cores were produced in type 1 muscle fibers by tenotomy of rat soleus muscle. The morphology and histochemistry of the muscle fibers was established by light microscopy on cryostat sections stained for hematoxylin-eosin or myofibrillar ATPase and on semithin plastic sections. The ultrastructure was visualized on thin plastic sections. On 6 micrometers of freeze-dried cryosections, energy dispersive X-ray microanalysis was performed on muscle fibers visualized in the scanning-transmission mode of electron microscopy. This procedure permitted quantification of different intracellular elements such as sodium (Na), chlorine (Cl), potassium (K), magnesium (Mg), sulphur (S), and phosphorus (P). Spectra from core fibers could easily be compared with those of normal fibers. A conspicuous finding was an increased Na and Cl content and a decreased K content in core fibers compared to normal fibers. It is known that core fibers produced after tenotomy exhibit distinct changes in plasma membrane morphology similar to that found in Duchenne muscular dystrophy (DMD). The results in this study point to a change in normal intracellular ion composition which could be a result of a deficiency of mechanisms maintaining normal membrane ion gradients.

Animals↗

PubMed1992

The toxic effects of bis (tributyltin) oxide on the rat thoracic aorta.

The toxic effects of bis (tributyltin) oxide (TBTO) on the ultrastructure and permeability of rat thoracic aorta were studied electron microscopically and the accumulation sites of tin were determined with an X-ray microanalyzer. Male Wistar rats received 0.05ml/kg of TBTO as an emulsion in 1 ml of distilled water through a stomach tube. After time intervals of 2, 4, 6, 8, 10, 12 h after intubation, thoracic aortae were isolated and prepared for electron microscopy. Marked swelling of mitochondria in the aortic endothelial cells appeared at 4 h after TBTO treatment. By x-ray microanalysis, tin L-alpha peaks (3.44 keV) were obtained from these swollen mitochondria. Subendothelial edema progressed between 6 and 8 h after TBTO treatment. By tracer experiment, it was seen that large amounts of peroxidase reaction products filled the expanded subendothelial space. At 12 h after TBTO treatment, degenerative changes of the endothelial cells were prominent. These results indicated that orally administered TBTO accumulated in the mitochondria of the endothelial cells of thoracic aorta. The direct toxic effects of TBTO on mitochondria might induce severe damage to the endothelial cells and cause disturbance of the permeability barrier function of the endothelial layer and subendothelial edema.

Animals↗

PubMed1994

Bioactive glass-ceramic containing crystalline apatite and wollastonite initiates biomineralization in bone cell cultures.

Rat bone cells were cultured in the presence of bioactive glass-ceramic containing crystalline apatite and wollastonite. Scanning electron microscopy observations of the surface of the seeded ceramic disks revealed that cells attached, spread, and proliferated on the material surface. Soaking in cell-free culture medium showed that no change occurred in the surface structure. However, when cultured with bone cells and observed under a transmission electron microscope, an electron-dense layer was noted initially at the surface of the material, before bone formation occurred. In addition, energy-dispersive X-ray microanalysis demonstrated the presence of calcium and phosphorus in this layer. Progressively, during the following days of culture, active osteoblasts synthetized and laid down an osteoid matrix composed of numerous collagen fibrils arranged either parallel or perpendicularly to the first-formed electron-dense layer. Mineralization initiated on the ceramic surface dispersed then along the collagenous fibrils, leading to a mineralized matrix which surrounded the ceramic particles. These results demonstrate the capacity of apatite-wollastonite glass ceramic to initiate biomineralization in osteoblast cultures and to achieve a direct bond between the surface apatite layer of the bioactive glass-ceramic and the mineralized bone matrix.

Animals↗

PubMed1991

Cadmium toxicity in the thyroid gland of pregnant rats.

The toxic effects of cadmium on the thyroid gland of pregnant rats were studied with an electron microscope and an X-ray microanalyzer. Serum levels of thyroid hormones (T3 and T4) were also analyzed. Deterioration of the rough-surfaced endoplasmic reticulum occurred in the thyroid follicular epithelium on the fifth day of cadmium treatment. Large intracellular vacuoles, which arose from dilated cisternae of the rough-surfaced endoplasmic reticulum, were fused together, and marked swelling of the mitochondria was also noted. Thyroglobulin-secreting granules at the apical cytoplasm were decreased in number. By energy dispersive X-ray microanalysis, cadmium peaks were preferentially obtained from swollen mitochondria in the follicular epithelial cells. Serum levels of T3 and T4 were significantly decreased in cadmium-treated rats dams when compared to those of controls. In the present experiment, cycloheximide also caused degenerative changes in the rough-surfaced endoplasmic reticulum and the disappearance of thyroglobulin-secreting granules. Cycloheximide is a known inhibitor of protein synthesis on cytosolic ribosomes. These results indicated that accumulated cadmium in the mitochondria of thyroid follicular epithelial cells might disturb the oxidative phosphorylation of this organelle and the loss of energy supply possibly caused the inhibition of the synthesis and release of thyroid hormones.

Animals↗

PubMed1983

Calcium transport mechanism in molting crayfish revealed by microanalysis.

Crayfish provide a good model in which to study the transport mechanism of Ca ions. During the molting stage, decalcified Ca ions are transferred into the blood and accumulate in the gastrolith epithelium, after which a gastrolith is formed on the surface of the epithelium. The gastrolith is dissolved in the stomach after molting, and the Ca is reabsorbed and redistributed throughout the newly formed exoskeleton. We studied the mechanism of Ca transport by cytochemical precipitation of Ca ions and by electron microanalysis, including X-ray microanalysis (EDX) and electron energy-loss spectroscopy (EELS), with a computer. In EDX analysis, the fine precipitates of K-antimonate in the gastrolith mitochondria clearly defined Ca with antimony; we also observed a large amount of Ca-oxalate in the mitochondria, and Ca-K X-ray pulses were clearly defined. Ca-K X-rays were also detected from fresh freeze-substituted mitochondria. Finally, we succeeded in taking a Ca-L EELS image from the mitochondria of fresh freeze-substituted thin sections. Only a very small amount of Ca was detected from the cell membrane and other organelles. Ca-adenosine triphosphatase (ATPase) and Mg-ATPase activity was also very clearly demonstrated in the mitochondria. These enzymes may play an important role in Ca metabolism.

Adenosine Triphosphatases↗

PubMed2002

Effects of a potassium nitrate mouthwash on dentinal tubules--a SEM analysis using the dentine disc model.

The concept of tubular occlusion as a method of dentine desensitisation is a logical conclusion from the hydrodynamic hypothesis put forth by Brannström. The aim of this study was therefore to investigate qualitatively by SEM whether a 3% potassium nitrate/0.2% sodium fluoride mouthwash occluded tubule orifices, and by x-ray microanalysis, to characterise the nature of the deposits if any, following application. Following the 'dentine disc model' methodology 1mm thick tooth sections from unerupted molars were obtained. These were treated with the test and control mouthwashes and subjected to scanning electron microscopy. If any deposits were seen, they were to be subjected to elemental analysis using the energy dispersive x-ray analyser. Examination of all the dentine disc surfaces, treated by water (control), active and control mouthwashes demonstrated that none of the treatments, at any of the time intervals, had any visible effect on the dentinal tubule orifices i.e. there was no dentinal tubular occlusion seen. The results suggest that potassium nitrate does not reduce dentinal hypersensitivity, at least by tubule occlusion. This could mean that there is a different mechanism of action, which could not be detected by this in vitro model.

Dentin↗

PubMed2000

In vitro bone formation on a bone-like apatite layer prepared by a biomimetic process on a bioactive glass-ceramic.

In this study we have investigated the behavior of fetal rat osteoblasts, cultured up to 23 days, on a bioactive apatite-wollastonite (AW) glass-ceramic and on the same material on which a carbonated apatite layer had been formed by a biomimetic process (AWa). At the last day of culture, the specific activity of alkaline phosphatase activity, as determined biochemically, was about 30% greater on AWa compared with AW disks. After the cell layers had been scraped off, scanning electron microscopic (SEM) observations of the materials' surfaces revealed that mineralized bone nodules remained attached to both surfaces but in larger amounts on AWa. X-ray microanalysis indicated the presence of calcium (Ca) and phosphorus (P) in the bone tissue throughout the AWa surface and Ca, P, and silicon (Si) on the AW surface. The AW/ and AWa/bone interfaces also were analyzed after fracturing of the disks. The interfacial analysis showed firm bone bonding to the AW and AWa surfaces, confirmed by the X-ray microanalytic mappings. These results indicate the importance of surface composition in supporting differentiation of osteogenic cells and the subsequent apposition of bone matrix, which allows a strong bond of the bioactive materials to the bone. Furthermore, prefabrication of a biologic apatite layer by a method that mimics biomineralization could find application to bone-repairing materials.

Alkaline Phosphatase↗

PubMed1987

Early effects of alloxan on rat submandibular gland.

Early effects of alloxan on structure and function of rat submandibular gland were investigated by light and electron microscopy, X-ray microanalysis, and by analysis of secreted saliva. Alloxan induced, already within 3 h, intracellular accumulation of mucus, as also evidenced by an increase in the cellular calcium concentration. In addition, 3 to 6 h after injection of alloxan, the granular duct cells were found to be vacuolated, which could suggest a cytotoxic effect of alloxan on this cell type. Alloxan did not significantly affect the flow rate of submandibular saliva after pilocarpine stimulation, and also did not significantly alter the concentrations of sodium, potassium, calcium and protein in the final saliva. The effects of alloxan on the acinar cells of the rat submandibular gland and the absence of effects on fluid secretion by this gland are in accordance with a direct or indirect inhibition of the cAMP system.

Alloxan↗

PubMed1988

Restorative dental materials: scanning electron microscopy and x-ray microanalysis.

Restorative dental materials include the materials used to repair damaged teeth and/or replace missing teeth. The definition could be extended to include a much broader group of dental materials, but this paper concentrates only on those materials used to restore the crown portion of damaged teeth. Auxiliary materials, materials for removable denture prostheses, and root canal materials are excluded. Progress and recent research utilizing SEM (Scanning Electron Microscopy), EDS (Energy Dispersive Spectroscopy), and some related methods are presented for the following dental materials: dental amalgam, enamel and dentin bonding agents, dental composites, dental cements, casting alloys for crowns and bridges, and ceramic-metal and ceramic restorative materials. In addition to the basic characterization of these materials by SEM/EDS techniques, examples of replication methods for SEM study of restorative materials in situ are discussed. Some examples are also presented in the direct use of SEM/EDS for characterization of changes and degradation of restorative materials which occur during clinical use.

Dental Materials↗

PubMed1987

Possible physico-chemical processes in human dentin caries.

This study correlated ultrastructural observations on the presence of beta-tricalcium phosphate (beta-TCP) in arrested dentin caries with physico-chemical observations on the in vitro formation of Mg-substituted beta-TCP. The ultrastructural studies were made using high-resolution transmission electron microscopy (TEM) with the capability of microdiffraction and microanalysis on sites less than 10 nm in diameter. Mg-substituted beta-TCP was obtained, by a precipitation method, from solutions with Mg/Ca molar ratios of 5/95 and higher. Such correlations led to the postulation of a possible chronological sequence of physico-chemical events occurring at the crystal level during the progress and arrest of caries in human dentin. It is suggested that the initial mechanism for the observed occurrence of large crystals of Mg-substituted beta-TCP and of apatite in the tubule lumen is due to the dissolution of the dentin mineral (a CO3- and Mg-rich calcium OH-apatite) and reprecipitation of Mg-substituted beta-TCP, followed by that of CO3- and Mg-poor apatite.

Calcium Phosphates↗

PubMed1983

Use of x-ray microanalysis to monitor diffusion of Zn from a cement into human dentin.

Energy dispersive x-ray spectrometry (EDAX system), with scanning electron microscopy was used to detect diffusion of Zn from a source in human dentin and the system was tested for sensitivity and reproducibility. Sections of human teeth in which a ZnO-eugenol cement had been placed in a cavity in the dentin in vivo were prepared and x-ray microanalytical measurements carried out. We found that values of counts for Zn, Ca and P in the same field were linear up to a total counting time of 60 sec. We further found that reproducibility of values between repeat examinations of the same specimens on different days was excellent. The concentration of Zn in the dentin decreased exponentially with distance from source within the distance tested. We conclude that the system can be used to detect trace concentrations of Zn, and that accordingly the diffusion behavior of a variety of ions in dentin could be monitored.

Calcium↗

PubMedDate not supplied

[Scanning electron microscopy (SEM) and microanalysis (EDS) applied to the study of biomaterials for dental use. 6].

The study considers the use of scanning electron microscopy (SEM) and EDS microanalysis applied to the study of numerous mineral-based biomaterials of common use in odontostomatology. The products studied are the following: reabsorbable Dac Blu, non reabsorbable Dac Blu, non reabsorbable atomized Dac Blu, non rabsorbable fine Dac Blu, reabsorbable Biocoral 450, Calcitite 2040-12, Orthogel, Apagen, BTF 65, Calcitite 4060-2, Osprogel, Bio-Oss, Biostite, Ospro-vit, Merck Hydroxyapatite. By means of SEM it was possible to study the morphology and the microchemistry of the various biomaterials so as to have information about their physical and chemical characteristics, such as the crystalline form, the crystalline aggregations, the space dimensional distribution of the pores and check the possibilities of composition variability. All of these factors are fundamental to evaluate the functional biocompatibility of a biomaterial, once that its performance in a biological environment is known.

Biocompatible Materials↗

PubMed1991

Replacement of calcium by cadmium ions from Ca-affinity sites localized in different cytoplasmic compartments of Acanthamoeba cells.

In Acanthamoeba cells both Ca and Cd may be precipitated in different cytoplasmic compartments forming electron-opaque deposits, as shown in cells treated with glutaraldehyde supplied with either Ca or Cd respectively. It was found by semiquantitative X-ray microanalysis that the transfer of cells containing Ca-deposits to glutaraldehyde supplied with Cd causes a considerable replacement of Ca by Cd: in deposits formed at cell membrane, in cytoplasm, and in mitochondria the total weight percentage of Cd amounted to over 90, only in deposits formed in vacuoles the value was about 80. The replacement was not prevented by the presence of Ca in the transfer medium. When cells containing Cd-deposits were transferred to Ca-supplied medium, Cd predominated as well, its total weight percentage also amounting to over 90 in all the examined deposits. The results suggest that calcium bound in different cell structures may be easily replaced by cadmium, but not conversely, which suggests that Cd is more firmly than calcium linked to many cell constituents well preserved by fixation.

Acanthamoeba↗

PubMed1986

Microscopical comparison of cotton, corn, and soybean dusts.

Specialized analytical methods are required for identification of components of agricultural dusts such as those generated in harvesting, transportation, storage, and processing of cotton, corn, and soybeans. The larger particles and trash components of the dusts can often be identified visually or with the aid of an optical microscope (OM). The respirable portion of the dust, that which causes lung dysfunction, retains few structural features for identification. Electron microscopy and X-ray microanalysis, together with special optical microscopical techniques, can be used to characterize these microdusts. Combination studies with scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) analysis of cotton dusts have shown the presence of mineralogical particles probably of a soil origin and materials that can be associated with plant parts. Even in screened and filtered cotton dusts, fibrillar fragments are usually present due to their ability to penetrate openings the size of their diameters. The corn and soybean dusts studied were different from the cotton dust in that the large fibrillar component of the cotton dust was absent in the screened grain dusts. However, these dusts consisted of structurally unrecognizable particles that appeared similar to those found in cotton dust. In addition they contained many spheroid particles identified as starch. Dusts from all three sources were found to agglomerate into larger particles, some of which were still less than 10 micron. This agglomeration could confuse the instrumental measurement of dust particle size.

Dust↗

PubMed1981

Novel role of calcium in exocytosis: mechanism of nematocyst discharge as shown by x-ray microanalysis.

Mature nematocysts of the sea anemones Rhodactis rhodostoma and Anthopleura elegantissima contain a fluid that has a high concentration of solutes and is extraordinarily rich in calcium (ca. 500-600 mmol/kg wet weight); this contrasts with the surrounding cytoplasm which is rich in potassium but poor in calcium. The undischarged capsule is surrounded by a membrane that probably acts as a selective permeability barrier between the cytoplasm and the nematocyst fluid. During discharge the nematocyst moves to the surface of the nematocyte and comes into contact with the external sea water medium. Calcium, which may be bound to proteins in the undischarged state, is rapidly lost from the fluid; at the same time, sea water enters the capsule. In vitro experiments have already shown that calcium loss increases the osmotic pressure of the capsular fluid, causing an influx of water from the external medium; this influx appears to increase the hydrostatic pressure inside the capsule to the point that the thread everts explosively.

Animals↗

PubMed1997

An investigation of potential desensitizing agents in the dentine disc model: a scanning electron microscopy study.

Cervical dentine sensitivity (CDS) may be defined as pain arising from exposed dentine. The prefix cervical indicates the location of the sensitivity and/or its subsequent treatment. Currently the most accepted mechanism of intradental nerve activation associated with dentine sensitivity appears to be hydrodynamic in nature. The concept of tubule occlusion as a method of dentine desensitization is a logical conclusion of the hydrodynamic theory. The authors employed the dentine disc model, qualitative scanning electron microscopy (SEM) and X-ray microanalysis to investigate whether selected desensitizing agents occlude dentinal tubule orifices. Strict control procedures have been used together with various methods of application to apply these agents to human dentine discs. SEM was used to examine the degree of deposit left by the various agents on disc surfaces and X-ray microanalysis was employed to characterize the elemental composition of the deposit. Analysis of selected agents, both prior to and after application on dentine discs was performed for comparative purposes. The degree of retention of the surface deposit upon rotation with saliva supernatant for 6 h was also studied. The results of this study indicated that ferric oxalate, the active ingredient of Sensodyne Sealant, which produced initial crystal-like structures, occluding almost all the tubule orifices was superior to potassium oxalate (Butler Protect). Of the over-the-counter (OTC) desensitizing products tested, both silica- and calcium-based abrasive components were observed both on the surface and within the tubules, indicating a certain degree of therapeutic potential for these two components. These findings suggest that certain desensitizing agents have tubule occluding properties as observed in this in vitro system which, in turn, may indicate a therapeutic potential in vivo.

Calcium↗

PubMed2005

A chemical signal possibly related to physiology in fossil cells detected by energy dispersive X-ray microanalysis.

Energy dispersive X-ray microanalysis (EDXMA) is a widely used tool employed to detect elemental composition and its spatial distribution in a sample without causing damage. Charcoalified cytoplasm is a new type of fossil material that came to people's attention only recently. In this paper, EDXMA is used for the first time to detect the spatial elemental distribution in charcoalified cytoplasm of two fossil plants that are more than 100 million years old. The results demonstrate certain elemental distribution patterns within charcoalified cytoplasm and the surrounding cell walls. Based on the results from cytological studies of extant material, the heterogeneous spatial elemental distribution within the charcoalified cytoplasm has the potential to be related to the maturation of cells, the presence of certain organelles, and the physiology of these organelles. This is the first chemical signal detected in cytoplasm residue that can possibly be related to plant physiology. This paves the way for further research on fossil cytoplasm, which will better our understanding on the physiology of fossil plants.

Carbon↗

PubMed1978

Calcium and sulphur in neurosecretory granules and calcium in mitochondria as determined by electron microscope x-ray microanalysis.

Sections of neurosecretory cells fixed in glutaraldehyde and osmium tetroxide were studied by means of an EMMA-4 analytical microscope. Secretory granules in neurosecretory cells of the corpus cardiacum and of the brain, both in the desert locust Schistocerca and in the blowfly Calliphora, as well as neurosecretory granules in posterior pituitaries of the frog Rana and of the albino rat all contain a high concentration of calcium. A distinct sulphur peak was also a constant feature. In neurosecretory cells of the corpus cardiacum of Schistocerca the chromatin contained a high concentration of calcium. The mitochondria also contained much calcium, but part of this disappeared during preparation except when fixative and wash contained calcium chloride. By block staining with uranyl acetate most calcium is displaced from the mitochondria, whereas most of the calcium remains in the neurosecretory granules. Since the calcium peaks in spectra from neurosecretory granules appear of similar size, regardless of variations in the preparative procedure, this calcium must be firmly bound. The possible role of the calcium bound to the neurosecretory substance is discussed. The presence of sulphur in insect neurosecretory granules indicated the presence of a protein besides the hormone, i.e., an insect neurophysin.

Animals↗