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PubMed1979

Stereo-electron microscopy and energy-dispersive x-ray analysis of avian reticulocytes.

Utilizing the techniques of stereo-electron microscopy (stereo-EM) and energy-dispersive x-ray analysis (EDX), we have studied aspects of the ultrastructure of avian reticulocytes. Stereo-EM of thin sections (0.10 to 0.25 mum thick) stained with uranyl and lead revealed the three-dimensional arrangement of 25 nm chromatin fibers on the tangential surfaces of nuclei. Use of the Bernhard staining procedure in combination with stereo-EM permitted a three-dimensional view of the interchromatin spaces and channels leading to the nuclear pores, and of cytoplasmic polyribosomes. With either staining technique we frequently encountered in the cytoplasm clusters and paracrystalline arrays of electron-dense granules with granule diameters approximately 1/2 that of monomer ribosomes. These granules were highly electron-dense in unstained specimens and have been identified as intracellular ferritin on the basis of the similarity of their ultrastructural morphology to that of horse spleen ferritin and their high content of iron as determined by EDX. The possibility that these granules represent toxic products of phenylhydrazine treatment (Heinz bodies) is considered unlikely, since we have demonstrated in this study that Heinz bodies cannot be visualized in unstained preparations, do not reveal the same granular structure, and do not contain significant amounts of iron above background. The occurrence of intracellular ferritin is discussed in light of current concepts of iron transport and storage during erythropoiesis.

Anemia↗
PubMed1984

Experimental synovitis induced by aluminium phosphate in rabbits. Comparison of the changes produced in synovial tissue and in articular cartilage by aluminium phosphate, carrageenin, calcium hydrogen phosphate dihydrate, and natural diamond powder.

The goal of this experimental study was to examine the effect on articular tissue of tribasic aluminium phosphate (crystalline and amorphous forms) after intraarticular injection in rabbit and to compare it with that of various phlogistic compounds such as carrageenin, calcium hydrogen phosphate dihydrate and diamond powder, as a control. Synovium and cartilage were studied with light microscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive micro-analysis (EDM). Crystalline and amorphous aluminium phosphate could induce a synovitis with articular effusion in rabbits. With TEM, lysosomal inclusions of phagocytosed material were observed. Through SEM coupled with EDM, aluminium associated with phosphate was found in cellular elements.

Aluminum Compounds↗
PubMedDate not supplied

Study of the biological films formed during the pitting of aluminium in human plasma.

Film formation during the pitting corrosion of aluminium in human plasma is studied using conventional electrochemical techniques complemented with scanning electron microscopy as well as energy-dispersive x-ray, electron microprobe and immunoelectrophoresis analysis. The anodic polarization curve of aluminium in human plasma at 37 degrees C shows a passive region related to a low corrosion rate that extends up to -0.66 V (s.c.e.). At more positive potential values than -0.66 V, the breakdown of the oxide protective film occurs due to the chloride anions, leading to an intense localized dissolution of the metal (pitting corrosion). Scanning electron microscopy of the metal surface reveals a thick non-adherent precipitate covering pits of a crystallographic feature. Energy-dispersive x-ray and the microprobe analysis show the presence of aluminium, chloride and carbon signals. Immunoelectrophoresis of the precipitate resuspended in physiological solution shows a strong protein denaturization. Results suggest that the corrosion products are formed during pitting by the interaction of the saturated AlCl3 salt present within the pits and the adsorbed plasma proteins.

Aluminum↗
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↗
PubMed1980

A freeze-substitution method for localizing divalent cations: examples from secretory systems.

This paper presents a simple method for localizing calcium in its natural distribution. This method depends on freeze-substituting rapid-frozen tissue, and combines the spatial precision of conventional plastic sections with the reliable calcium localization characteristic of direct freezing methods. Calcium is retained in the tissue during freeze-substitution and subsequent processing, and its distribution in frog skeletal muscle suggests that it is not displaced during tissue processing or in the electron probe. Examples of new findings with this method are the presence of a postsynaptic sequestration system for cations entering at the neuromuscular junction, and a nonmitochondrial system in nerve muscle synapses that sequesters cations entering during depolarization-secretion coupling.

Animals↗
PubMedDate not supplied

[Potassium urate in urinary tract calculi].

In a study of renal calculi, performed with scanning electronic microscope, Edax, element mapping and semiquantitative analysis with a Nova 2 computer, we have found, among the urates, ratios K/Na from 0.016, in the almost pure monosodium urate stones, to 1.856 in other areas. The presence of monopotassium urate has, to our knowledge, no previous reference in the literature on human lithiasis.

Electron Probe Microanalysis↗
PubMed1981

Thiocholine methods for the demonstration of acetylcholinesterase in neuromuscular junctions.

The extensor digitorum longus muscles of rat were stained for the localization of acetylcholinesterase activity at the neuromuscular junctions. The modified methods of Koelle-Friedenwald and Karnovsky-Roots were used with acetylthiocholine iodide as the substrate. The merits and demerits of both these methods are discussed. TEM and SEM X-ray dispersive analyses of the muscle fibres treated histochemically by both the methods were also made in order to elucidate further the nature of the reaction products. Denervated muscles were subjected to similar treatment.

Acetylcholinesterase↗
PubMed1981

Calcium oxalate crystal growth in human urinary stones.

Calcium oxalate stones are very common and increasing. Crystal growth is no less important than the crystal nucleation in the pathogenesis of stone formation. The crystal growth was studied in human calcium oxalate stones by a combined electron microscopy and x-ray diffraction. The main mode of weddellite growth was interpenetration twinning of tetrahedral bipyramids. Bipyramids may form as initial crystal seeds, develop from anhedral crystals (crystals which lack flat symmetric faces) of spherular or mulberry shape, develop on the surface of preformed bipyramids by spiral dislocation mechanisms, or develop on whewellite crystal by heterogeneous nucleation and epitaxy. Heterogeneous nucleations of whewellite on weddellite, and calcium apatite on whewellite were also observed. Whewellite grew mainly by parallel twinning. Interpenetration twinning was exceptional. Transformation of anhedral to euhedral (completely bounded by flat faces that are set ar fixed angles to one another) whewellite occurred by parallel fissurations followed by brick wall like stacking of the crystals, while euhedral transformation of weddellite occurred by protrusion of bipyramids frm anhedral crystal surface. Occasionally, an evidence of crystal dissolution was noted. Although an aggregation of crystals is believed to play a pivotal role in stone nidus formation, growth in size of the formed crystals, and twinning and epitactic crystal intergrowth apparently play a significant role in the obstructive urinary stone formation.

Calcium Oxalate↗