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PubMed1981

Age related changes and osteochondrosis in swine articular and epiphyseal cartilage: light ane electron microscopy.

Age related changes and osteochondrosis in swine were studied using light microscopy and electron microscopy in articular cartilage and light microscopy and epiphyseal cartilage of swine from three days to 30 weeks of age. Thickness, cellularity and vascularity of both the epiphyseal and articular cartilage, decreased as the swine aged. Osteochondrotic changes included formation of "plugs" of cartilage indicating localized failure of ossification and separation and space formation in epiphyseal cartilage. Eosinophilic streaks and space formation in epiphyseal cartilage was observed in relation to epiphyseal separation. Electron microscopy showed a continuous fibrillar layer on the surface of the cartilage corresponding to the lamina splendens of light microscopy. This layer increased in the thickness and showed accumulation of amorphous material between the fibrils with aging. In the matrix, the orientation and distribution of the collagen fibers changed with growth and thicker fibers with clear sub banding were more common in older age groups. Also, necrotic cells, glycogen containing bodies and cellular debris were noticed in the matrix of normal cartilage in old animals. Chondrocytes in the younger cartilage showed accumulation of organelles responsible for protein synthesis; while Golgi bodies, vesicles, lysosomes, well developed foot processes and other inclusions were noticed in older cartilage. Cartilage erosions had a clumped and disrupted lamina splendens on the surface and electron lucent patches in the ground substances of the matrix and chondrocyte cytoplasm.

Aging↗
PubMed1997

Electron microscopy of chromatin.

Electron microscopy, with its ability to image DNA and nucleosomes, can provide a key visual link in the understanding of chromatin conformation. We discuss applications of EM to current chromatin research with emphasis on strategies that eliminate many of the potential problems associated with conventional EM preparative techniques. Cryo-electron microscopy (cryo-EM) of isolated chromatin, whereby samples are imaged "in solution" in thin vitrified films, is considered in detail, with emphasis on the recovery of three-dimensional information and on its application to linker DNA conformation and to salt-induced compaction. Factors that currently limit the technique, and the prospects of overcoming them, are also considered.

Chromatin↗
PubMed2003

A core-weighted fitting method for docking atomic structures into low-resolution maps: application to cryo-electron microscopy.

Cryo-electron microscopy of "single particles" is a powerful method to analyze structures of large macromolecular assemblies that are not amenable to investigation by traditional X-ray crystallographic methods. A key step in these studies is to obtain atomic interpretations of multiprotein complexes by fitting atomic structures of individual components into maps obtained from electron microscopic data. Here, we report the use of a "core-weighting" method, combined with a grid-threading Monte Carlo (GTMC) approach for this purpose. The "core" of an individual structure is defined to represent the part where the density distribution is least likely to be altered by other components that comprise the macromolecular assembly of interest. The performance of the method has been evaluated by its ability to determine the correct fit of (i) the alpha-chain of the T-cell receptor variable domain into a simulated map of the alphabeta complex at resolutions between 5 and 40 A, and (ii) the E2 catalytic domain of the pyruvate dehydrogenase into an experimentally determined map, at 14 A resolution, of the icosahedral complex formed by 60 copies of this enzyme. Using the X-ray structures of the two test cases as references, we demonstrate that, in contrast to more traditional methods, the combination of the core-weighting method and the grid-threading Monte Carlo approach can identify the correct fit reliably and rapidly from the low-resolution maps that are typical of structures determined with the use of single-particle electron microscopy.

Animals↗
PubMedDate not supplied

[In vitro study of the process of urinary calculi fragmentation with endoscopy, light microscopy, and scanning electron microscopy].

Stones with different compositions respond differently to shock wave lithofragmentation. Likewise, the various lithotrity systems used may have different effects on the stones. To determine the relationships between stone composition and their fragmentation patterns, we conducted an in vitro study using endoscopy, magnifying glass, light microscope and scanning electron microscope on fragments obtained after lithotrity of 60 pure stone with different compositions: calcium oxalate monohydrate and dihydrate (OXMH and OXDH), phosphocarbonate (PC), ammonium magnesium phosphate (AMF) and uric acid (UA). Fragmentation was carried out with 4 different lithofragmenting sources (electrohydraulic, piezoelectric, ultrasound and pulse laser). No morphologic differences in the fractures induced by the various lithofragmenting sources were demonstrated. OXMH and UA stones basically break up by intercrystalline fracture and splitting of their concentric plates. OXDH breaks up mainly by intercrystalline fractures aided by the fibrillar organic material and phosphocarbonates found in the intercrystalline spaces. Fragmentation in infective stones (AMF and PC) occurs across the intercrystalline surfaces and by intracrystalline fracture. Ammonium urate fragments break up by intracrystalline fractures that run across the equatorial plane of its characteristic acicular microspheres.

Crystallization↗
PubMed1979

[Comparative endoscopic, light microscopy and scanning electron microscopy studies of the gastric mucosa in patients with chronic uremia].

Ten patients suffering from chronic uremia were selected for comparison studies of gastric mucosa. With endoscopy erosive gastritis was seen in the corpus and antrum of five patients and in the fundus of two patients. Conventional microscopy (nine patients) revealed chronic gastritis I three times in the fundus and five times in the corpus. Gastritis II was localized once in the corpus and twice in the antrum. Gastritis III was present in the antrum of four patients. Under the scanning electron microscope lesions of gastric mucosa were present in all ten cases. Single cell necrosis (A), mucosal defects involving basal membrane (B), destruction of tunica propria (C), and muscularis mucosae with bleeding (D) were seen. Mucosal lesions A and B are early stages of gastric erosions. The most severe lesions were seen in the antrum mucosa with all three methods.

Chronic Disease↗
PubMed1988

The dento-gingival junction as seen with light microscopy and scanning electron microscopy.

The purpose of this paper is to review the anatomical relationship of the Dento-Gingival Junction as seen in the human dentition. The junction is described under light microscopy and then reviewed as seen in the SEM with the author's unpublished findings. The authors' material was derived from extracted human teeth with remaining marginal gingival tissue. The specimens were fixed with 2% glutaraldehyde in 0.15M sodium cacodylate buffer (pH 7.2) for 24 h. The specimens were then washed and freeze-fractured in Freon 113 using liquid nitrogen. Afterwards they were processed by freeze-drying or CPD methods, coated with gold, and placed in the scanning electron microscope (SEM) for viewing. These specimens demonstrated the presence of numerous Sharpey's fibers at the cemental surface. A large number of fibrils intermingled with the fibers to produce a dense mass of tissue. Junctional epithelium, with the adjacent homogeneous dental cuticle was demonstrated. Plaque deposits on the tooth surface extended to a cell-free zone. Morphological detail viewed with SEM and light microscopy are compared.

Freeze Fracturing↗
PubMed1977

Morphology of mouse epidermal cells in vitro: a scanning electron microscopy study.

Scanning electron microscopy of isolated epidermal cells from newborn mice grown in vitro showed that the cultures consisted of several morphologically different types of cells. Young cultures had many smooth, round cells while older cultures contained more cells with rough or ruffled surface and a varying number of flat, irregular cells. Probably, the various cell types corresponded to different stages of differentation (keratinization). Cultures that were grown in the presence of retinyl acetate (12.5 microgram/ml) had more round and smooth cells after several days in vitro than the controls. This could indicate that retinyl acetate delayed or altered cell differentiation. Scanning electron microscopy of the cultures consistently showed that the cells were situated at different layers. The apparent monolayer seen by phase contrast microscopy therefore seems to be an optical phenomenon due to projection of the cells onto the same plane.

Animals↗
PubMed2005

Critical assessment of the speckle statistics in fluctuation electron microscopy and comparison to electron diffraction.

The technique of fluctuation electron microscopy (FEM) is applied to thin films of amorphous germanium and of polycrystalline gold in a transmission electron microscope. Even though the method was introduced as a tool for quantitative analysis of structural fluctuations in amorphous materials, the basic principles are applicable to any disordered specimen independent of the dimension of disorder. Hence, we extended the technique of FEM to a well-known specimen, gold, whereby it was possible to reinterpret the results of the measurements on amorphous germanium. The hollow-cone dark field images, the statistical analysis of which is the basis of FEM, are examined with respect to the effects of frequency filtering, and are compared to electron diffraction. We find that the angular dependence of the normalised variance, as measured by FEM, yields information similar to the average intensity of hollow-cone dark field image series. Both plots are basically identical to a scan through a selected-area diffraction pattern convoluted by the corresponding angular resolution function. Hence, it appears questionable whether standard FEM analysis provides more information than the classical pair distribution function, which is experimentally limited to short-range order. Frequency selective analysis of the normalised variance, however, gives supplementary information on preferred inter-atomic distances related to the medium-range order of the specimen.

Journal Article↗
PubMed1999

Electron microscopy study of intrahepatic ultrasmall superparamagnetic iron oxide kinetics in the rat. Relation with magnetic resonance imaging.

Ultrasmall superparamagnetic iron oxide (USPIO) contrast agents for use in magnetic resonance imaging (MRI) are currently undergoing clinical evaluation. However, the images observed and the kinetic profiles obtained differ from one agent to another. In this study, BD IX rats received an intravenous penis injection of the USPIO contrast agents AMI-HS and AMI-227. A cytologic study of the liver was performed, and the data obtained were compared with those of MRI. Images acquired in light microscopy, transmission electron microscopy, microanalysis and electron diffraction provided data on the cell categories involved in the processing of these contrast agents, the importance and modalities of each category relative to this processing, and the modalities of agent elimination. AMI-HS was rapidly removed from the bloodstream by Kupffer's cells and hepatocytes and then eliminated through bile ducts. AMI-227 remained much longer in the blood compartment since it was processed very slowly by endothelial and Kuppfer's cells in the near absence of hepatocytic participation and thus of elimination by the bile ducts. These results allowed us to base our interpretation of MRI sequences on cytologic observations.

Animals↗
PubMed2006

Reflection contrast microscopy: The bridge between light and electron microscopy.

Reflection contrast microscopy (RCM) is a light microscopic method to image cells at high definition and enhanced sensitivity compared to conventional bright-field microscopy. RCM images have very high contrast, which makes them easily applicable for digital image analysis. Because ultrathin sections are mostly used in this method, RCM also functions by bridging light with electron microscopy: the combination of ultrastructural with histochemical studies. RCM can also replace electron microscopy for rapid and simple screening of large quantities of samples for immunocytochemical staining. Special attention is paid to small biological objects, which have to be processed for RCM. If you encounter the limits of brightfield microscopy, in resolution, sensitivity or handling of the specimen, RCM will be a feasible option. Reflection contrast microscopy methods use only slightly adjusted electron microscopy methods for specimen preparation. Therefore, many familiar techniques for ultrathin specimen preparation can be applied. It is essential that only refractive index differences exist in those areas that are of interest and that the further specimen is as optically homogenic as possible, with a refractive index as close to that of glass as possible. Therefore, plastic embedding is recommended.

Animals↗
PubMed1995

Using laser scanning confocal microscopy as a guide for electron microscopic study: a simple method for correlation of light and electron microscopy.

Anatomic study of synaptic connections in the nervous system is laborious and difficult, especially when neurons are large or have fine branches embedded among many other processes. Although electron microscopy provides a powerful tool for such study, the correlation of light microscopic appearance and electron microscopic detail is very time-consuming. We report here a simple method combining laser scanning confocal microscopy and electron microscopy for study of the synaptic relationships of the neurons in the antennal lobe, the first central neuropil in the olfactory pathway, of the moth Manduca sexta. Neurons were labeled intracellularly with neurobiotin or biocytin, two widely used stains. The tissue was then sectioned on a vibratome and processed with both streptavidin-nanogold (for electron microscopic study) and streptavidin-Cy3 (for confocal microscopic study) and embedded in epon/araldite. Interesting areas of the labeled neuron were imaged in the epon/araldite blocks with laser scanning confocal microscopy and then thin-sectioned at the indicated depth for electron microscopic study. This method provides an easy, reliable way to correlate three-dimensional light microscopic information with electron microscopic detail, and can be very useful in studies of synaptic connections.

Animals↗
PubMed1996

A total sample preparation method for the measurement of airborne asbestos and other fibers by optical and electron microscopy.

A total sample preparation method utilizing one membrane filter for all or some of the measurements by phase contrast optical microscopy (PCM), optical microscopy (OM), dispersion staining polarized microscopy (DS/PLM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), was developed in order to evaluate airborne asbestos and other mineral fibers comprehensively, including fiber number, sizes and types, in various environments. This method consists of two alternate procedures: parallel and serial preparation. The former uses different portions of a filter for each measurement of PCM, OM, DS/PLM, SEM and TEM. The latter uses a single filter portion for all OM, SEM and TEM measurements by which the same area and same fibers on the filter can be observed. This allows fiber numbers to be directly compared using these measurements on the same filter area, and the fibers observed by OM can be also examined by SEM and/or TEM equipped with an energy dispersive X-ray spectrometer (EDX) to determine the types and precise sizes. Using this method, it was found that OM measurements developed in this study can visualize thinner fibers than PCM measurements and make it easier to count fibers. We also found that currently used PCM measurement can detect fibers thicker than about 0.4-0.5 microns in diameter. This total sample preparation method can be used not only for air samples, but also for liquid and biological tissue samples.

Air Pollutants, Occupational↗
PubMedDate not supplied

Electron microscopy in neuromuscular disorders.

Electron microscopy has a strategic position in the diagnosis of neuromuscular disorders. In muscular fibers, the main abnormalities include vacuoles, inclusion bodies, and myofibrillar disorganization with or without abnormal inclusion material. Vacuolar changes include lipidic and glycogenic storage vacuoles, rimmed vacuoles, and lysosomal and autophagic vacuoles. Accumulation of abnormal inclusion material is found in nemaline myopathy, actinopathies, and hyaline body myopathy. Myofibrillar disorganization involves cores, multiminicores, and myosin chain depletion. Myofibrillar myopathies associate a pathologic pattern of myofibrillar dissolution and ectopic protein expression. They can be divided into two groups: myofibrillar myopathies with multiple expression proteins and myofibrillar myopathies with desmin and alphaB-crystallin expression only. In these two conditions, electron microscopy shows accumulation of a granulofilamentous material immunoreactive for desmin. At least three genes are implicated: desmin, alphaB-crystallin, and myotilin. Lastly, electron microscopy serves to identify changes, pathogenic or not, which are not shown up by light microscopy. Moreover, electron microscopy gives insight on pathophysiological mechanisms and can guide molecular genetics analysis.

Humans↗
PubMed1977

Correlative scanning and transmission electron microscopy of glomeruli.

Scanning electron microscopy was performed on 125 human renal specimens and control rat kidneys in conjunction with light microscopy and transmission electron microscopy. Specimens were prepared by glomerular isolation, free hand slicing, alcohol cryofracture, and polyethylene glycol embedding and ultraplaning. Heavy metal secondary electron sources on the tissues were produced by osmic acid, thiocarbohydrazide, osmic acid treatment (O-T-O) followed by gold-palladium coating, or by staining with uranyl acetate and lead citrate. Critical point drying was used uniformly. Useful observations of normal rat glomeruli were made. In the study of diseased human glomeruli, podocyte changes were classed as cytoplasmic projection, foot process changes, and changes of necrosis or basement membrane denudation. Artificial lesions of compression and contamination were defined. Cryofractured and ultraplaned stained specimens were very useful for studying diseased tissues. These methods offer the opportunity to increase our conceptual and diagnostic understanding of glomerular disease.

Animals↗
PubMed1989

[Application of electron microscopy to tumor diagnosis--observation of 1000 cases with both light and electron microscopy].

We observed 1000 cases human tumors by electron microscope, as compared with by light microscope. Results were classified into four groups: First, the diagnosis by both light microscope and electron microscope were the same in 92 per cent of total cases. Second, diagnosis by light microscope was completely changed by the use of electron microscope, and the correct diagnosis was determined only by electron microscope in 4 percent when light microscope failed. Third, although major diagnosis of some tumors by both light and electron microscope was the same, by electron microscope, the diagnosis was extended and supplemented in 3 per cent. Finally, diagnosis was still unclear in 1 per cent. We think that ultrastructural evaluation contributes to diagnosis in 7 per cent of all the cases. Electron microscope plays a very important role in the differential diagnosis of tumors, especially, small cell malignant tumors, and pleomorphic malignant tumors, and also in determination of two-directional or multi-directional differentiation of some tumors.

Diagnosis, Differential↗
PubMed1988

Preparation of cultured mammalian cells for transmission and scanning electron microscopy using Aclar film.

Common methods for the preparation of cultured cells for concurrent light microscopy (LM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) are not completely satisfactory. This article describes how we grow mammalian cells on plastic disks made from Aclar film. Aclar is a transparent fluorinated-chlorinated thermoplastic that contains no volatile components and is, for all practical purposes, chemically inert. Cells adhere to it readily and remain attached after fixation, dehydration, and critical-point drying or embedding. The film also accepts heavy metal coating by ionic bombardment and is extremely stable in the vacuum of the SEM. LM observations are unhindered by Aclar, since the film is as transparent as glass. Fluorescence microscopy is possible with this film, since it exhibits no detectable autofluorescence. During SEM observation, the film has great dimensional stability, and the cells and heavy metal coating remain attached to the Aclar even under high-resolution operating conditions. TEM processing of specimens grown on Aclar is simplified by the fact that Aclar does not stick to the epoxy resins used in EM. Furthermore, Aclar is easily sectioned and does not damage knives used in ultramicrotomy. The use of Aclar film considerably simplifies the preparation of cultured cells for all types of microscopy. This method is particularly useful in correlating surface features between SEM and TEM observations.

Animals↗
PubMed1992

Degradation, amorphization, and recrystallization of ion bombarded Si(111) surfaces studied by in situ reflection electron microscopy and reflection high energy electron diffraction techniques.

In this paper we report the effect of noble gas ions bombardment on the degradation of atomically flat Si(111) surfaces at room and high (400 degrees C-600 degrees C) temperatures. Reflection high energy electron diffraction (RHEED) and reflection electron microscopy (REM) have been used to characterize the topography and structure of the as-implanted and post annealed surface layers. It is shown that the fading of the specularly reflected beam is not directly related to the amorphization of the surface. This experimental study has also evidenced the difficulties one meets to regrow a defect-free material after amorphization by noble gas bombardment. For high temperature for which the amorphization is not possible, the surface loses its stepped structure and turns into a monocrystalline but atomically rough surface. This roughness is a function of substrate temperature.

Argon↗