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PubMed1987

Cell fractions from rat rib growth cartilage. Morphological and X-ray microanalytical investigation.

For in vitro studies of differentiation and proliferation of chondrocytes, a need arose to prepare enriched cell fractions for analysis of the effects of different growth promoting factors. Therefore chondrocytes were isolated from rat rib growth cartilage in young rats by collagenase digestion and subsequently three cell fractions were prepared by centrifugation in a step gradient of Percoll. In a previous paper, matrix molecules synthesized by each fraction were characterized biochemically. In the present study, ultrastructure and elemental content of the fractionated chondrocytes were analyzed by scanning electron microscopy, transmission electron microscopy, and energy dispersive X-ray microanalysis. DNA-synthetic activity was measured by means of autoradiography of 3H-thymidine incorporating cells. Both morphology and elemental concentrations differed between fractions and were characteristic for each fraction. The cell fraction with the lowest density consisted of large, polygonal cells that became flattened in culture. The reduced synthetic activity and markedly lowered K content of these cells suggest that they originate from the hypertrophic zone of the growth plate. The cells in the fraction with the highest density were rather homogeneous in size and shape, and had a well developed rough endoplasmic reticulum and Golgi complex, characteristic of proliferating and resting chondrocytes. Concentrations of P and K were also significantly higher in this fraction. The fraction with intermediate density contained an admixture of cells with a predominance of proliferating cells with high DNA-synthetic activity.

Animals↗
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↗
PubMedDate not supplied

Evaluation of the effect of lichens on ceramic roofing tiles by scanning electron microscopy and energy-dispersive spectroscopy analyses.

The effect of the actions of some lichens on the quality of ceramic roofing tiles was investigated in view of textural and microstructural changes considering their biocorrosion resistance. Two types (extruded and pressed) of the real ceramic roofing tiles aged 6 to 10 years, as well as the ceramic model systems formed with the additives of the specific chemical composition Cu-slag powder (10 wt%) and CuO powder (1 wt%), treated with various concentrations of oxalic acid (0.01 wt%, 0.1 wt%, and 4 wt%) were investigated. The thalli of lichen (Verrucaria nigrescens) growth on ceramic roofing tile were examined by scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). Investigation by SEM and EDS gave information regarding the ultrastructure characteristics of the thallus and the lichen-ceramic tile contact zone, allowing the observation of the hyphal penetration and filling up of the fissures and cracks by the lichens' hyphae. The CuO as the raw mixture additive changed the quality of the surface of the ceramic model systems as it has increased resistance to oxalic acid actions. The textural changes in the ceramic model systems and the formation of the identified destructive crystal phase, whewellite, were slowed down. The fundamental interactions between lichens and ceramic materials of the model systems have been identified as physico-chemical processes based on oxalic acid actions, which could cause ceramic matrix deterioration and consequently aging of ceramic roofing tile systems.

Biodegradation, Environmental↗
PubMed2000

A study of drug-carrier interactions in dry powder inhaler formulations using the Andersen cascade impactor, X-ray microanalysis and time of flight aerosol beam spectrometry (TOFABS).

The purpose of this study was to determine the in vitro deposition of both drug (albuterol sulfate) and carrier (lactose) particles in relation to each other from a dry powder inhaler formulation using an Andersen cascade impactor (ACI) and time of flight aerosol beam spectrometry (TOFABS). In addition, scanning electron microscopy (SEM) combined with X-ray microanalysis was employed to distinguish albuterol sulfate from lactose. Drug particles apparently penetrated deeper into the impactor than lactose particles contained in the formulation. In some certain stages of impactor, drug particles were separated from lactose particles. Although the TOFABS cannot distinguish between albuterol sulfate and lactose, the TOF spectra obtained from the Aerosizer would appear to be partly indicative of the interactions which exist between drug and carrier. One symmetrical TOF peak was obtained from drug or lactose alone. The TOF peak of the drug was always lower than the TOF of lactose. The times obtained for each powder between experiments were highly reproducible and typical of material and particle size. The use of SEM-X-ray microanalysis also allowed some qualitative characterization of shape and state of association of the two components.

Aerosols↗
PubMed1989

Structural analysis of phleboliths and salivary calculi.

Three phleboliths and ten salivary calculi in the submandibular duct were studied with scanning electron microscopy (SEM) and computer aided microanalyser (CMA). The surface of the phleboliths was rather even with some irregularity. According to their surface structure the salivary calculi were divided into three types: the rock-like type, the granular type, and the globular type. The phleboliths were classified into two types according to their cut surface: the calcified-core type, and the uncalcified-core type. The core structure was similar to the surface structure in the calcified-core type of phleboliths, but in the salivary calculi the core structure was different from the surface structure in that the cut surface of the core was an accumulation of circular or polygonal structures forming a honey-comb pattern which was surrounded by small projections distributed radially. On the basis of these results some etiological factors of phleboliths and salivary calculi are discussed.

Electron Probe Microanalysis↗
PubMed1993

[An ultrastructural analysis of the peritubular dentin and of the tubular lumen in healthy teeth].

In this study the authors examined some specimens of fractured dentine of embedded healthy teeth, of people aged between 20 and 30. Connecting the scanning electron microscopy to a system of computerised analysis of spectrometry (EDS) allowed the analysis of the qualitative composition of the specimens. Therefore, the authors described the tubular structure of the sound, the peri- and the intertubular dentine, the winding course of the dentinal tubules and in some specimens, the presence of cylindrical structures inside the tubules. The EDS analysis demonstrated that these tubular structures have the same composition as the intertubular dentine. Former studies described hollow cylindrical structures having a similar morphology solely as a response of the odontoblasts to white spots. On the contrary, in this study it was demonstrated that it is possible to find cylindrical structures which are definitely mineralized in sound teeth without caries. However, the presence of such formations is not concomitant with the disappearance of peritubular dentine which is a typical structural modification of the pathological advancement of the carious lesion.

Adult↗
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↗
PubMed2002

XPS study for the microstructure development of hydroxyapatite-collagen nanocomposites cross-linked using glutaraldehyde.

X-ray photoelectron spectroscopy (XPS) was measured for the dry body of hydroxyapatite (HAP)-collagen (COL) nanocomposites cross-linked using glutaraldehyde (GA). Survey scan XPS showed the elemental spectra of N, C, O, Ca and P, which came from HAP and COL. The covalent bond formation between Ca2+ of HAP and RCOO- of COL molecule was confirmed by XPS. The bridge formation between COL fibers could be assessed from C1s and N1s band spectrum. The dehydration of swelling water during drying led to the reduction of linking distance for pendant GA between COL fibrils and contributed to further cross-linkage reaction. Cross-linkage induced the enlargement of length scale unit of COL. The modification of length scale was doing the key role of structure manipulation in the cross-linked HAP-COL nanocomposites.

Anisotropy↗
PubMed1991

Laser scanning and confocal microscopy of daunorubicin, doxorubicin, and rhodamine 123 in multidrug-resistant cells.

The multidrug-resistant gene (MDR1) encodes an energy-dependent drug efflux pump (P-glycoprotein) for many anti-cancer drugs. We have studied the intracellular distribution of rhodamine 123 (R123), daunorubicin (DN), and doxorubicin (DOX) in cells expressing a human MDR1 gene. The distribution of these fluorescent drugs was measured by laser scanning microscopy and confocal microscopy. We devised a new method for analysis of fluorescence line scan data to determine the intracellular distribution of fluorescent probes. This method and confocal microscopy showed that R123, DN, and DOX are localized to both plasma membrane and intracellular compartments in multidrug-resistant cells. When the cells are treated with verapamil, an inhibitor of the multidrug transporter, the amount of DOX, DN, and R123 associated with the cell rises. After inhibition, the relative distribution of DOX and DN between the cell surface and intracellular structures does not change dramatically. However, R123 tends to relocalize to intracellular sites from predominantly plasma membrane sites, indicating that this dye behaves differently than the anti-cancer drugs. These results show the subcellular distributions of R123, DN, and DOX in plasma membrane, cytoplasm, and intracellular membrane systems, but do not allow definitive distinctions among existing models of how P-glycoprotein affects the distribution of drugs.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
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↗
PubMed1999

Metallosomes.

Structures and ordered arrays containing organometallic particles have potential application in nanofabrication, smaller computer components, optical devices, sensors, and membrane probes and as detection agents. Here, we describe construction of gold clusters covalently attached to lipids and their use in forming typical lipid structures: micelles, liposomes ("metallosomes"), and sheets on an air-water interface. Two sizes of gold clusters were used, undecagold, with an 11-gold atom core 0.8 nm in diameter, and the larger Nanogold, with a 1.4-nm gold core. The morphology of the structures formed was determined by electron microscopy at a resolution at which single gold-lipid molecules were visualized. Further modification by additional catalytic metal deposition enhanced detectability. The approach is flexible and permits a wide variety of metal particle structures to be created using known lipid structures as templates. Additionally, these gold-lipids may serve as useful membrane labels.

Calcium↗
PubMed1994

Depth of penetration and appearance of Grossman sealer in the dentinal tubules: an in vivo study.

Five teeth extracted after chemomechanical preparation (group A) and 11 extracted 1 to 7 yr after endodontic treatment (group B) were selected for this study. A 1% NaOCl was used for irrigations and a lateral condensation technique with a Grossman-type sealer was used for obturation. The teeth were fractured and prepared for and viewed by a scanning electron microscope equipped with an electron dispersive spectrometer. All root canal walls of group A were covered with a thick smear layer. Sealer, either rod-like or granular in appearance and barium free, was present in the majority of the dentinal tubules of group B usually at a distance up to 200 microns from the root canal walls; in two cases up to 900 microns. Sealer was found deepest in the middle third of the root. The smear layer did not stop sealer from entering the dentinal tubules. The differences in the depth of penetration or in the appearance of the sealer cannot be attributed to the different time periods the teeth remained in the arch after endodontic treatment.

Adult↗
PubMed2003

Electrochemistry of nano-scale bacterial surface protein layers on gold.

The mechanism of the recrystallization of nano-scale bacterial surface protein layers (S-layers) on solid substrates is of fundamental interest in the understanding and engineering of biomembranes and e.g. biosensors. In this context, the influence of the charging state of the substrate had to be clarified. Therefore, the electrochemical behaviour of the S-layers on gold electrodes has been investigated by in-situ electrochemical quartz microbalance (EQMB) measurements, scanning force microscopy (SFM) and small-spot X-ray photoelectron spectroscopy (SS-XPS) of potentiostatically emersed substrates. It was shown that the negatively charged bonding sites of the S-layer units (e.g. carboxylates) can bond with positively charged Au surface atoms in the positively charged electrochemical double layer region positive of the point of zero charge ( approximately -0.8 V vs. saturated mercury-mercurous sulphate electrode). Surface conditions in other potential regions decelerated the recrystallization and fixation of S-layers. Time-resolved in-situ and ex-situ measurements demonstrated that two-dimensional S-layer crystal formation on gold electrodes can occur within few minutes in contrast to hours common in self-assembled monolayer (SAM) generation. These results proved that the recrystallization and fixation of 2D-crystalline S-layers on an electronic conductor can be influenced and controlled by direct electrochemical manipulation.

Bacterial Outer Membrane Proteins↗
PubMed2006

Acid-etching effects in hypomineralized amelogenesis imperfecta. A microscopic and microanalytical study.

OBJECTIVES: The purpose of this study was to use quantitative x-ray microprobe analysis with scanning electron microscopy to define the morphostructural and calcification patterns in the enamel of teeth with the hypomineralized variant of amelogenesis imperfecta. STUDY DESIGN: We compared 5 fragments of permanent human canines from patients with clinically diagnosed hypomineralized amelogenesis imperfecta and 5 normal permanent canines from subjects without amelogenesis imperfecta. All specimens were etched with phosphoric acid for morphological and microanalytical examination. RESULTS: Two types of etching patterns were found; in addition, islets of pattern I were seen within areas of pattern II. Microanalysis detected no significant differences in calcium concentration between specimens with amelogenesis imperfecta and normal control specimens after acid etching. Pattern III was not observed. CONCLUSIONS: The changes and their distribution in the enamel structure after 30 s of acid etching are described in teeth with this rare disorder. Although these data seem to coincide with alterations in prism development, no alterations in calcium concentration were found.

Acid Etching, Dental↗
PubMed1983

Scanning electron microscopy in gallstone research.

Nidation of gallstones by inorganic or organic Ca salts was studied in 336 consecutive cases by SEM/EDXA and additional methods (X-radiography, X-diffraction, IR spectroscopy). SEM/EDXA proved to be a useful method in studying very small radio-dense nuclei, since common means of phase analysis are limited because of the small amounts of material to be analyzed. In 20.3% stones had radio-dense nuclei composed of either Ca-phosphate- and/or Ca-carbonate microcalculi. Ca-palmitate and/or pigments were at the centre of stones showing a less dense X-shadow. Nidation of cholesterol stones by defined pigment microcalculi was observed in 10 cases. Microstructures, for instance Ca-carbonate- and pigment microcalculi of identical structure to the central nidi, were found in corresponding bile sediments, confirming the role of such structures in gallstone nidation. Two structural features were identified in pigment stones: small, irregular granules, and glassy, poorly structured masses. Ca-bilirubinate calculi were built up from granules while the so called 'black' stones were composed entirely of the glassy masses or contained both structural elements, indicating that bilirubinate may be involved in the formation of some black stones, too. As revealed by EDXA and EPMA Ca was predominant in both subtypes while the black stones additionally contained Cu, Fe and, above all, considerable amounts of S. the latter was found to be in a low, non-SO4-valence state.

Bile↗
PubMed1994

Translational diffusion measurements of a fluorescent phospholipid between MDCK-I cells support the lipid model of the tight junctions.

The diffusion of a lipid fluorescent analogue across tight junctions in MDCK-I cells was studied by FRAP measurements. Cells were labelled with C6-NBD-PC at the apical cell membrane. Transepithelial resistance of MDCK-I cells was found to be higher than 3000 omega x cm2, which indicates the presence of a very tight epithelium. After bleaching of large areas, fluorescence recovery was detected by confocal laser scanning microscopy, and diffusion coefficients were calculated. The lipid probes were able to diffuse to neighbouring cells as long as tight junctions between cells were intact. The average diffusion coefficient of the lipid was determined to be 5 x 10(-9) +/- 3.5 x 10(-9) cm2/s (n = 12) at room temperature. In controls, where the tight junctions were opened by complexing Ca2+ ions with EDTA, no recovery was observed. Redistribution of C6-NBD-PC into the bleached apical membrane did not occur in experiments at temperatures below 10 degrees C. We conclude that the tight junction structure can be described by the lipid model, assuming the formation of an intermembranous hexagonal cylinder of lipids for the cell contact. In this model the exoplasmatic leaflets of the plasma membranes are continuous, thus allowing free diffusion of suitable lipids from one cell to another.

Animals↗
PubMed2002

Scanning electrochemical microscopy of living cells. 4. Mechanistic study of charge transfer reactions in human breast cells.

Scanning electrochemical microscopy (SECM) has recently been employed for probing the redox properties of individual mammalian cells. It was shown that intracellular redox activity can be probed noninvasively by measuring the rate of mediator regeneration by the cell. Depending on the properties of the mediator species (e.g., formal potential, ionic charge, and hydrophobicity), different steps can limit the rate of the mediator regeneration reaction. This paper describes the evaluation of several factors that determine the rates of different steps of the process. These include intracellular concentration of redox centers, mixed redox potential inside the cell, and the rate of membrane permeation by mediator species. The kinetic analysis has been carried out to clarify the origins of different rates of the overall charge-transfer reaction in different cell types and with different redox mediators. The results can be used to facilitate differentiation between different types of cells, for example, normal and metastatic breast cells, on the basis of differences in redox responses.

Breast↗
PubMed1972

Location of calcium within Bacillus spores by electron probe x-ray microanalysis.

Spectroscopic microanalysis of the element-characteristic X rays produced by a scanning electron microprobe was employed to detect calcium and carbon in both intact and thin-sectioned spores of Bacillus cereus T and B. megaterium QM B1551. Linear scan profiles and multilinear scan images of the X-ray emissions for calcium (Ca(Kalpha)) were compared with those for carbon (C(Kalpha)) as an index of mass. Location was accomplished by stereological comparisons with secondary electron images and conventional transmission electron micrographs. Although the elements could be detected at the attogram level theoretically, spatial resolution was limited to approximately 500 to 1,000 nm in an intact spore, e.g., by the primary electron beam diameter, the electron-excited spore microvolume, and the type of specimen support. The resolution was improved to approximately 100 to 200 nm by use of thin-sectioned spores, with precautions to prevent calcium leakage from the specimen during preparations. In both intact and sectioned spores, calcium was distributed throughout the spore, similarly to carbon, and concentrated mainly in a central region corresponding to the spore protoplast.

Bacillus cereus↗