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Accurate analysis of urinary calculi is essential for greater understanding of urinary stone disease and initiation of effective management and preventive measures. Quantitative and qualitative analysis of uroliths are discussed in this article.
Thalli of the red alga Audouinella saviana were exposed to 600 microM Cd2+ (LC50), 1000 microM Cd2+ and 1500 microM Cd2+ (final concentrations) for 5, 10 and 15 days (each dose) by adding cadmium nitrate to the culture medium. Untreated thalli were set in triplicate as controls for each experiment. Ultrastructural modifications due to cadmium ad/absorption were observed by TEM/SEM electron microscopy. SEM-EDS X-ray microanalysis, definining the accumulation sites, was performed on cryoprepared samples. TEM studies showed striking changes in the plasmalemma of treated algae, which became irregular and convoluted. Electron-transparent exocytic vesicles, possibly related to cell wall polysaccharide synthesis, were observed. The appearance of ribosomes and Golgi bodies, not significantly present in the cytoplasms of untreated cells, suggested enhanced protein and carbohydrate biosynthesis. The cell walls lost their initial grooves and became smooth and thick. More or less electron-dense vesicular systems were formed. Electron-dense sphaeroids occurred in the plasmalemma-cell wall interface, in the cell wall itself and in nearby vesicular membrane systems. Many small vacuoles containing large metal complexes were formed. Complexes were then sequestered into a large vacuole. SEM observations demonstrated that the cell wall and the membrane systems were the most involved in the defense responses. EDS-X-ray microanalysis confirmed the presence of cadmium in these compartments. Chloroplasts, where no Cd2+ signal was detected, were the least affected organelles, showing only a partial disorganization after lengthy exposure to high Cd2+ concentrations.
The s-state approach is useful for analysing transmission electron microscope images of a thin crystalline foil consisting of well-separated atomic columns. It assumes that the signal collected (e.g., the annular dark-field image, the EELS spectrum) can be attributed to only the lowest-energy bound eigenstate of the two-dimensional projected potential of a single column. When, however, columns are close, the form of the bound states depends on more than one column, which implies that interpretation of the signal may not be so simple. For closely spaced columns we show that the simple s-state approach fails for the case of a sub-Angstrom probe initially centred on one column of a pair, because two bound states are excited. The energy in the probe is almost completely transferred to the neighbouring column after it has propagated some tens of nanometres through the foil and then is transferred back. Signals which relate directly to the local probe intensity (e.g. annular dark-field formed by thermal diffuse scattering, EELS) must be analysed in terms of the two bound states. Accurate calculations of bound states of pairs of columns are more demanding than for a single column but sufficient accuracy can be achieved from knowledge of the 1s-states of isolated columns. We provide formulae for the bound states of a column pair. These can be used to determine if image analysis requires the extension to the s-state approach described in this paper.
The objective of this work is to fabricate a scanning probe sensor that combines the well-established method for atomic force microscopy, employing a micro-machined Si cantilever and integrated tip, with a probe for the optical near field. A photosensitive pn-junction is integrated into the tip for that purpose and an Al coating is applied to the tip. It comprises an aperture of 50-70 nm in diameter at the apex of the tip in order to spatially limit the interaction of the tip to the optical near field of the sample. Characterization of the tip and first results of simultaneously recorded force and photon images are presented.
The static and kinetic frictional coefficients of commercially pure titanium brackets were evaluated in the passive configuration in the dry and wet states against stainless steel, nickel-titanium, and beta-titanium arch wires. For comparison, stainless steel brackets were evaluated under identical conditions. Titanium brackets were grayer in color and rougher in texture than the stainless steel brackets. Bracket slots were up to 0.002 inch greater than the nominally stated values. Remarkably, the static and kinetic frictional coefficients of the couples formed by titanium and stainless steel brackets were comparable. When evaluated against stainless steel and nickel-titanium arch wires in the dry state at 34 degrees C, the static coefficient averaged.12 and.20, respectively, independent of bracket alloy. When evaluated against stainless steel and nickel-titanium wires in the wet state at 34 degrees C using human saliva, the static coefficient averaged.15 and.20, respectively, independent of bracket alloy. Only the beta-titanium arch wires increased by about 15%, when tested in either the dry or the wet state against titanium versus stainless steel brackets. Noteworthy, too, was the decrease of both coefficients in the beta-titanium wire couples from their previously reported values. Analyses of electron spectroscopy for chemical analysis spectra and depth profiles show that these new brackets are titanium only in the bulk. Indeed the immediate surfaces are composed of, at least, 80 atomic percent (at.%) carbon and oxygen; whereas, the titanium that is present (>11 at.%) is mostly in the form of titanium dioxide. The presence of this quite thin passivating layer, which resides on top of an oxygen-hardened titanium substrate, reduces the galling and fretting that would normally be expected in such materials. Pending the outcome of future angulation tests, these frictional measurements show that titanium brackets are not only comparable to stainless steel brackets but also are more biocompatible with nickel having been eliminated from their constitution.
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Addition of stoichiometric amounts of low valent metal halides to liquid ammonia solutions of disodium chalcogenide (Na(2)E; E = S, Se, Te) afforded a range of both crystalline (PbE (E = S, Se, Te), TlE (E = S, Se), Tl(5)Te(3), Ag(2)E (E = S, Se, Te)) and X-ray amorphous (MS (M = Ni, Cu, Zn, Cd, Hg), M(2)E(3) (M = Ga, In; E = S, Se, Te), HgE (E = Se, Te), CuE (E = S, Se, Te), Cu(2)S) metal chalcogenides in good yield (95%). Reactions between metal halides and sodium pnictides (Na(3)Pn; Pn = As, Sb) in liquid ammonia also afforded X-ray amorphous material (M(3)Pn(2), M = Zn, Cd; MPn, M = Fe, Co, Ni) in good yield (95%). Isolation of the metal chalcogenides and pnictides was achieved through washing with CS(2) and distilled water. All reactions were complete within 36 h. Products were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDXA), electron probe analysis, FT-IR spectroscopy, Raman spectroscopy, microanalysis, and band gap measurements. Annealing amorphous material at 250-300 degrees C for 48 h induced sufficient crystallinity for analysis by X-ray powder diffraction.
This communication reports the findings of the investigation of the electrochemical (EC) oxidation of the important bimolecular guanosine (Gs) by scanning electrochemical microscopy (SECM) using carbon fiber ultramicroelectrodes (CF-UMEs) as the probe and substrate. The first attempt is to try to gain a steady-state voltammogram for EC oxidation of Gs at the CF-UME probe in aqueous buffer solutions with three different pH values. Experimental results indicate that due to serious adsorption of Gs on the CF-UME surface, an "S-shaped" steady-state voltammetric curve, which is required for SECM studies, cannot be obtained in aqueous solutions. To solve this adsorption problem, a series of experiments for studying the EC behavior of Gs in DMF are carried out. A well-defined "S-shaped" steady-state cyclic voltammogram (CV) could be achieved at the CF-UME in DMF containing 0.1M TBAPF6 as the supporting electrolyte. By combining several EC techniques, including cyclic voltammetry at glassy carbon (GC) macroelectrode and CF-UMEs, and chronoamperometry, the general chemical characteristics and EC behavior of Gs in DMF solution are studied. Furthermore, SECM detection of Gs*+, the radical cation of Gs electrogenerated in its first oxidation, is carried out by using feedback and tip generation/substrate collection modes in a nanogap configuration. Gs*+ has been electrochemically detected for the first time, with an estimated lifetime of </=40 mus and E degrees = 1.55 V versus NHE for the Gs/Gs*+ couple.
The elements present in the fungal structures produced by Piedraia hortae in vivo and in vitro have been investigated using electron microscopy X-ray microanalysis. Phosphorus, sulphur and calcium were detected in the nodules which developed on hair and on colonies on culture. These elements belong to the extracellular material that compacts the pseudoparenchymatous organization of the fungus. They may be present due to the capacity of melanin-like pigments to sequester ions and/or they may form part of the sulphates and phosphates of the polyanionic mucopolysaccharides that constitute the extracellular material. Environmental contaminants such as aluminium, silicon and iron were detected exclusively on the surface of the nodule. They were deposited or linked to the residual molecules produced during the breakdown of the cuticular keratin. The advantages of these techniques for elucidating the chemical nature of fungal structures are discussed.
BACKGROUND: Mucocutaneous depositions of various metals such as silver, lead, gold, arsenic, mercury, iron, and bismuth have been previously published. Heavy metal deposition typically occurs in the setting of either prolonged topical application to intact skin, topical application to eroded or ulcerated skin, as a result of either parenteral administration, or due to penetrating traumatic exposure. METHOD: We report a unique case of mucocutaneous pigmentation occurring in a snow skier after topical application of a zinc-containing sunblock. Formalin-fixed paraffin-embedded tissue was utilized for electron microscopy. RESULT: Backscatter electron imaging and energy dispersive spectroscopy revealed that the dominant metal present was zinc. CONCLUSIONS: Mucocutaneous deposition of metals is enhanced by damage to the surface epithelium. Metal-containing topical agents, although commonly used, may rarely result in a permanent pigmentary alteration. We believe similar cases of mucocutaneous deposition of zinc exist; however, as these may be currently misdiagnosed as amalgam tattoos, the true incidence of this disorder is presently undefined.
The element concentrations in various intra- and extracellular compartments of the tip of the rat renal papilla were determined during antidiuresis using electron microprobe analysis. Urinary concentrations (means +/- SEM) were: urea, 1509 +/- 116; potassium, 268 +/- 32; sodium, 62 +/- 19 mmoles X 1(-1); and osmolality, 2548 +/- 141 mOsm X kg-1. Electrolyte concentrations in the interstitial space were: sodium, 437 +/- 19; chloride, 438 +/- 20; and potassium, 35 +/- 2 mmoles X kg-1 wet wt. The vasa recta plasma exhibited almost identical element concentrations. The values in the papillary collecting duct cells were: sodium, 28 +/- 1; chloride, 76 +/- 3; potassium, 135 +/- 3; and phosphorus, 316 +/- 7 mmoles X kg-1 wet wt. Similar concentrations were observed in the papillary epithelial cells. In interstitial cells potassium and phosphorus concentrations were virtually identical to those of the collecting duct cells, whereas sodium and chloride concentrations were higher by about 30 mmoles X kg-1 wet wt. The element composition of the various papillary cells is, thus, not substantially different from that of proximal tubular cells. This finding demonstrates that cellular accumulation of electrolytes is not the regulatory mechanism by which papillary cells adapt osmotically to their high environmental osmolality and sodium chloride concentration.
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Irritant substances have been shown to induce elemental changes in human and animal epidermal cells in situ. However, skin biopsies are a complicated experimental system and artefacts can be introduced by the anaesthesia necessary to take the biopsy. We therefore attempted to set up an experimental system for X-ray microanalysis (XRMA) consisting of cultured human keratinocytes. A number of methodological aspects were studied: different cell types, washing methods and different culture periods for the keratinocytes. It was also investigated whether the keratinocytes responded to exposure to sodium lauryl sulphate (SLS) with changes in their elemental composition. The concentrations of biologically important elements such as Na, Mg, P and K were different in HaCaT cells (a spontaneously immortalized non-tumorigenic cell line derived from adult human keratinocytes) compared to natural human epidermal keratinocytes. The washing procedure and time of culture influenced the intracellular elemental content, and rinsing with distilled water was preferred for further experiments. Changes in the elemental content in the HaCaT cells compatible with a pattern of cell injury followed by repair by cell proliferation were seen after treatment with 3.33 microM and 33 microM SLS. We conclude that XRMA is a useful tool for the study of functional changes in cultured keratinocytes, even though the preparation methods have to be strictly controlled. The method can conceivably be used for predicting effects of different chemicals on human skin.
Distraction osteogenesis in rabbit mandibles after osteotomy can be used as an experimental model to study the microstructural features of mineralization of callus under defined mechanical loads. Our aim was to study the relation between the micromotions in the gap and the resulting features of mineralization of the matrix. We found that assembly of collagen and formation of crystals depended on the magnitude of the mechanical stress applied. At physiological bone strains (2000 microstrains), the callus had collagen type I in a mature bone-like extracellular arrangement, whereas at 20000 microstrains bundles were orientated predominantly towards the tension vector. Maximum loads (200000 microstrains) resulted in disorganized assembly of the collagen. Quantitative energy-dispersive analysis by X-rays confirmed that high strains were associated with substantially lower concentrations of calcium and phosphate. In contrast to bone-like apatitic formation of crystals at physiological strains, significantly fewer but larger crystals were detected by electron diffraction analysis in samples exposed to high strains. We suggest that mechanical stress regulates the assembly and mineralization of collagen during distraction osteogenesis.
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STATEMENT OF PROBLEM: It has been reported that the bond strength of composite to demineralized dentin is lower than that to sound dentin. This can be a problem in the success of so-called sealed restorations. PURPOSE: The aim of this study was to evaluate the effect of fluoride application on the tensile bond strength of self-etching adhesive systems to demineralized dentin. MATERIAL AND METHODS: One hundred twenty extracted bovine incisors were ground flat with 600-grit silicone carbide paper. Ninety teeth were then immersed in acetate buffer (pH 4.0) to form demineralized dentin. These teeth were randomly divided into 3 groups of 30 each: surfaces treated with fluoride solution (Group NF), surfaces treated with fluoride solution followed by a water rinse (Group RF), and control surfaces with no pretreatment (Group C). The remaining 30 teeth comprised a group with normal dentin surfaces (Group S). Each group was further divided into 3 subgroups of 10 each to test the bond strength test of Clearfil SE Bond, Unifil Bond, and Mac-Bond II. Tensile bond strengths (in MPa) were measured with a universal testing machine at a crosshead speed of 0.5 mm/min. Mean bond strengths were analyzed by 2-way analysis of variance and Fisher's PLSD (P =.05). SEM observations of the surfaces before and after priming and at resin-dentin interfaces in each group were performed. Elemental analysis of the dentin surfaces before priming was also carried out. RESULTS: The bond strengths of the adhesives to demineralized dentin in Groups NF, RF, and C were significantly lower than that of the normal dentin in Group S (P <.05). The mean bond strengths of the 3 adhesives in Group NF were higher than those in Groups RF and C, but a significant difference was observed only when Clearfil SE Bond was used (P <.05). In SEM images the open dentinal tubules on the surface and the resin tag formation at the resin-dentin interface were apparent in Group NF but were not observed in Groups RF and C. On elemental analysis, considerable amounts of fluoride and calcium were detected in the surfaces of Group NF. CONCLUSION: Within the limitations of this study, the surface treatment with fluoride solution supported the resin tag formation at the resin-dentin interface and slightly improved the bond strength of the self-etching adhesive systems tested to demineralized dentin. This result indicated that the fluoride treatment to demineralized dentin might contribute to the success of the sealed restoration.
Though only actual local free Ca2+ concentrations, [Ca2+], rather than total Ca concentrations, [Ca], govern cellular responses, analysis of total calcium fluxes would be important to fully understand the very complex Ca2+ dynamics during cell stimulation. Using Paramecium cells we analyzed Ca2+ mobilization from cortical stores during synchronous (< or = 80 ms) exocytosis stimulation, by quenched-flow/cryofixation, freeze-substitution (modified for Ca retention) and X-ray microanalysis which registers total calcium concentrations, [Ca]. When the extracellular free calcium concentration, [Ca2+]e, is adjusted to approximately 30 nM, i.e. slightly below the normal free intracellular calcium concentration, [Ca2+]i = 65 nM, exocytosis stimulation causes release of 52% of calcium from stores within 80 ms. At higher extracellular calcium concentration, [Ca2+]e = 500 microM, Ca2+ release is counterbalanced by influx into stores within the first 80 ms, followed by decline of total calcium, [Ca], in stores to 21% of basal values within 1 s. This includes the time required for endocytosis coupling (350 ms), another Ca2+-dependent process. To confirm that Ca2+ mobilization from stores is superimposed by rapid Ca2+ influx and/or uptake into stores, we substituted Sr2+ for Ca2+ in the medium for 500 ms, followed by 80 ms stimulation. This reveals reduced Ca signals, but strong Sr signals in stores. During stimulation, Ca2+ is spilled over preformed exocytosis sites, particularly with increasing extracellular free calcium, [Ca2+]e. Cortically enriched mitochondria rapidly gain Ca signals during stimulation. Balance calculations indicate that total Ca2+ flux largely exceeds values of intracellular free calcium concentrations locally required for exocytosis (as determined previously). Our approach and some of our findings appear relevant also for some other secretory systems.
Cobalt and nickel, matrices of hard metal, have been shown to be respiratory sensitizers. Airborne dust at hard metal-grinding worksites in a factor with a work-force of about 180 grinders was analysed for cobalt and nickel. The electron-microscopic X-ray microanalysis of airborne dust particles demonstrated that they had the same metallic components as hard metal products. Andersen sampling revealed that 66% of total dust was respirable (< 7 microns). Consecutive personal sampling for individuals indicated log-normally distributed concentrations of total dust and cobalt. Of the workers surveyed, 12% (16 out of 133) were exposed to cobalt at more than 50 micrograms m-3, while 1.5% (two out of 133) were exposed to nickel concentrations of more than 50 micrograms m-3. A correlation between cobalt exposure concentrations and nickel concentrations for individuals was significant and positive. Further improvement of the working environment is necessary because of the hazard caused by exposure to cobalt and nickel.