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PubMed1994

Value of electron microscopy in diagnosis of renal disease.

AIMS: To assess the role and value of electron microscopy in the diagnosis of renal disease. METHODS: Retrospective evaluation of 88 renal biopsy specimens received for primary diagnosis by assessment of the contribution of electron microscopy to the final diagnosis in the knowledge of the light microscopy and immunofluorescence findings. RESULTS: Electron microscopy had an important diagnostic role in 75% of cases and was essential or necessary for diagnosis in 25%. In 25% of cases electron microscopy was considered unhelpful in diagnosis. CONCLUSION: Electron microscopy has an integral role in the diagnosis of renal disease, and tissue should be taken for electron microscopy in all cases if possible. In some selected cases once the light microscopy and immunofluorescence findings are known it may be possible to forego electron microscopic examination. Electron microscopy is particularly useful in the differential diagnosis of minimal change disease and the nephrotic syndrome.

Adolescent↗
PubMed1987

Colloidal gold fluorescent microspheres: a new retrograde marker visualized by light and electron microscopy.

A new retrograde tracer, rhodamine latex microspheres, permits labeled neurons to be visualized with fluorescence light microscopy. However, their use has been limited to the light microscope. We now have developed colloidal gold fluorescent microspheres which identify retrogradely labeled neurons first by fluorescence microscopy and then by electron microscopy. This new fluorescent/EM tracer will find widespread use in the field of neuroscience to elucidate the ultrastructural integrity of neuronal networks.

Animals↗
PubMed1997

Light and scanning electron microscopy of the porcine mesometrial and paraovarian lymphatic networks.

Uterine lymphatics were examined in 38 pigs using light microscopy, stereomicroscopy, and scanning electron microscopy. Uterine lymphatics were initially filled with plastic materials: Microfil for stereomicroscopy, Mercox-corrosion cast for scanning electron microscopy (SEM), and Micropaque for x-ray photographs. Lymph precollectors of the uterine horns formed two superficial layers, ventral and dorsal. At the level of the ovary, precollectors joined to become collector lymph vessels, which entered nearby lymph nodes. Among the lymph vessels emanating from the uterus, there was a characteristics band of lymphatics that bordered on the isthmus of the oviduct. These passed toward the ovary to form the paraovarian lymphatic plexus. Segments of collector lymphatics were longer than precollectors, had thicker walls consisting of endothelial cells, smooth muscle (uniformly forming a continuous band around lymphatics) and fibroblasts. Both precollector and collector lymphatics were covered and surrounded by a fine network of blood microvessels (vasa-vasorum) especially well seen in corrosion casts (SEM).

Animals↗
PubMed1979

The influence of the buffer on maintenance of tissue lipid in specimens for scanning electron microscopy.

Preparations of tissues and cells for scanning electron microscopy (SEM) fixed with glutaraldehyde (G CHO) buffered in either Na-cacodylate or Piperazine-N-N' bis (20-ethanol sulfonic acid) (PIPES) differ in their morphology. The influence of the nature of these buffers in the tissue fixing and washing solutions on appearance in scanning electron microscopy is described. Biochemical determinations of lipid retention were performed on frog and chick embryos fixed for 24 hours with 3% G CHO in either 0.03 and 0.1 M PIPES (ph. 7.3) or 0.1 M Na-cacodylate (ph. 7.3). Embryonic tissue was chosen for its relatively high lipid content and delicacy which may be expected to enhance the sensitivity at which buffer effects become apparent. The comparable small and uniform sizes of the embryos minimize differences in fixation quality due to penetration. Lipid, recovered from homogenized tissue after treatment with chloroform/methanol/water (1:2.1:1, v/v) was considered as retained. The extraction results, which showed a significant reduction of lipid losses when PIPES buffer was used, are taken to account for the morphological differences observed in SEM and transmission electron microscopy (TEM).

Animals↗
PubMed2005

Visualisation of natural aquatic colloids and particles -- a comparison of conventional high vacuum and environmental scanning electron microscopy.

The applicability of environmental scanning electron microscopy (ESEM; imaging of hydrated samples) and conventional high vacuum scanning electron microscopy (SEM; imaging of dried samples at high vacuum) for the observation of natural aquatic colloids and particles was explored and compared. Specific attention was given to the advantages and limitations of these two techniques when used to assess the sizes and morphologies of complex and heterogeneous environmental systems. The observation of specimens using SEM involved drying and coating, whereas ESEM permitted their examination in hydrated form without prior sample preparation or conductive coating. The two techniques provided significantly different micrographs of the same sample. SEM provided sharper images, lower resolution limits (10 nm or lower), but more densely packed particles, suggesting aggregation, and different morphological features than ESEM, suggesting artefacts due to drying. ESEM produced less easily visualised materials, more complex interpretation, slightly higher resolution limits (30-50 nm), but these limitations were more than compensated for by the fact that ESEM samples retained, at least to some extent, their morphological integrity. The results in this paper show that SEM and ESEM should be regarded as complementary techniques for the study of aquatic colloids and particles and that ESEM should be more widely applied to aquatic environmental systems than hitherto.

Colloids↗
PubMed2001

Radiation damage of water in environmental scanning electron microscopy.

Specimen damage from the electron beam poses a considerable problem with electron microscopy. This damage is particularly acute in environmental scanning electron microscopy (ESEM) for two reasons. Firstly, owing to its ability to stabilise insulating and hydrated specimens, ESEM lends itself to polymeric and biological materials that are typically highly beam-sensitive. Secondly, water acts as a source of small, highly mobile free radicals, which accelerate specimen degradation. By taking the results of single-particle simulations of electron-water interactions, we determine the concentration of reactive species in a water specimen under ESEM conditions. We consider 12 species, which are produced in a Gaussian distribution, and annihilate according to a second-order reaction scheme. Self-diffusion along the concentration gradient is also modelled. We find that the dominant reactive species is the hydroxyl (.OH) radical. Annihilation of this species is suppressed due to the lower concentration of reactants. The relatively stable hydrogen peroxide is also found at large concentrations. By comparing two beam energies, 5 and 25 keV, we find a drastic increase in the quantities of reactive species produced with beam energy. The longer range of 25 keV primary electrons spreads reactive species over a wider region, which then decay far more slowly.

Journal Article↗
PubMed1994

Diagnostic electron microscopy in dermatology.

The diagnostic use of electron microscopy has greatly diminished since the advent of sophisticated immunohistochemistry, which is faster and cheaper. In several skin diseases, however, electron microscopy is still the test of choice. This article presents a discussion of some of the diseases diagnosed through the use of electron microscopy.

Connective Tissue Diseases↗
PubMed1984

Scanning electron microscopy of bacteria adherent to intravascular catheters.

Scanning electron microscopy was used to assess the morphological features of coagulase-negative staphylococci adherent to polyvinylchloride intravascular catheter specimens. Clinical specimens were obtained by using patient catheters from which coagulase-negative staphylococci (greater than or equal to 15 colonies per catheter) grew on semiquantitative blood agar roll cultures. In vitro specimens were prepared by a previously published technique in which sterile polyvinylchloride catheters were immersed in 10(6) CFU of coagulase-negative staphylococci per ml suspended in phosphate-buffered saline. Unused sterile polyvinylchloride catheters were also examined. Scanning electron microscopy of unused sterile polyvinylchloride catheters demonstrated multiple linear surface irregularities. Scanning electron microscopy of infected patient catheters showed a diffuse amorphous material covering the entire surface and the presence of bacteria which appeared anchored to that surface by several different means. These included a slime layer, "foot" processes, and lodgement in surface irregularities. Scanning electron microscopy of in vitro specimens demonstrated no background surface coating, but it did show attachment of cocci to the surface by the same mechanisms as described for clinical specimens. These observations of similar means of attachment in clinical and in vitro specimens suggest that intrinsic catheter surface properties, bacterial surface features, and perhaps coating with host substances may all play a role in bacterial attachment to intravascular catheters. More sophisticated analysis of these interactions may clarify mechanisms of pathogenesis.

Adhesiveness↗
PubMed2000

Bioaccumulation and localization of exogenous cadmium in a teleost by electron microscopy (TEM) and its specific quantitation by electron probe X-ray microanalysis (EPMA).

A cadmium bioconcentration study was carried out in a fresh water teleost, Colisa fasciatus, to study the bioaccumulation kinetics and fate of exogenous cadmium (Cd) in biological tissues. Study shows that on exposure of the fish to a sublethal concentration of cadmium in test water, Cd uptake results in its bioconcentration in gills, liver and muscle tissues. To explore whether the accumulated Cd reaches the membranes or inside the cells, transmission electron microscopy (TEM) of the thin sections of tissues was done after histochemical localization of Cd in cells by modified SST method. TEM studies of sections of gills, liver and muscle tissues showed the deposits of exogenous Cd (visualized as dense clouds) in biological cells. This suggests the presence of free or loosely bound Cd on the membranes and inside the cells, which in the presence of Na2S is converted into insoluble metal sulfides. Electron probe X-ray microanalysis (EPMA) studies confirmed the presence of Cd on the membrane surface as well as inside the cells of bioindicator organs suggesting involvement of membrane transport of exogenous Cd inside the cells and its deposition as loosely bound insoluble metal complexes.

Animals↗
PubMed1960

Electron microscopy of dental calculus.

Electron microscopy of ultrathin osmium-fixed sections of dental calculus, cut with a diamond knife without prior decalcification, revealed densely mineralized areas entrapping many degenerating microorganisms, within which were deposited similarly electron-dense crystals. Two principal forms of crystals were found, the predominant type being of the same order of magnitude and shape as those found in bone, and showing the typical characteristics of apatite in selected area electron diffraction patterns.

Apatites↗
PubMed1990

Changes in the esophageal epithelium in rabbits treated by Cis-dichlorodiammineplatinum as studied by electron microscopy.

The esophageal mucosa of the rabbit was investigated after a single dose of 5 mg Cis-Dichlorodiammineplatinum (Cis-DDP). Specimens were taken for scanning electron microscopy, transmission electron microscopy, and light microscopy. Examination was performed daily for 20 consecutive days. A cytotoxic effect was observed already the first day after injection with an intracellular oedema. Thereafter the height of the esophageal epithelium and the basal cell layer steadily decreased to a minimum day 11. This parallels the damaged microridges and an increased cell loss as revealed by scanning electron microscopy. At the end of the observation period the esophageal mucosa had completely restituted.

Animals↗
PubMed1977

[Study of the topography of the nitrogenase active center by the electron microscopy method with the use of the electron density labels].

The electron microscopy method has been used for studying the topography of the active centre of the nitrogenase in combination with the method of electron density labels. The active centre has been shown to place on the nitrogenase macromolecule asymmetrically. The non-heme iron atoms of the nitrogenase active centre have been regularly packed and located on the macromolecule as a quadrangular cluster closely to the surface of subunits. Two free sulfhydryl groups of the ATP-site of the nitrogenase active centre are in close proximity to the cluster. ATP-site of the nitrogenase active centre containing these groups is located on the Fe-enzyme, while the main part of the iron-containing cluster is located on the Mo-Fe-enzyme.

Adenosine Triphosphate↗
PubMed1981

Elastic fibers associated with collagenous fibrils surrounded by reticular cells in lymph nodes of the rat as revealed by electron microscopy after orcein staining.

Electron microscopy of the rat lymph node disclosed reticular cells in close association with bundles of collagenous fibrils 30-45 nm in diameter, and electron lucent "amorphous" substances surrounded by microfibrils 11 nm in diameter, with junctional complexes. The amorphous substances, distinctly revealed by orcein staining, and the microfibrils showed morphological characteristics of elastic fibers. Since elastase digestion of 2% glutaraldehyde fixed specimens induced the selective disappearance of the orcein-stainable substances, it was concluded that they are elastin. Elastin often had a close contact with the plasma membrane of reticular cells. It is suggested that reticular cells synthesize elastic fibers.

Animals↗
PubMed1979

Comparison of four-layer radioimmunoassay and electron microscopy for detection of human rotavirus.

A four-layer radioimmunoassay (RIA) using polystyrene beads as the solid phase, anti-rota guinea pig IgG as primary antibody, anti-rota rabbit IgG as secondary antibody, and 125I-labelled sheep anti-rabbit immunoglobulin as indicator antibody has been developed for the detection of human rotavirus in stool specimens. A comparison was made of the developed RIA, routine electron microscopy, and research electron microscopy of 147 unconcentrated stool specimens from patients with infantile gastroenteritis. In routine electron microscopy 17 (11.6%) false-positive or false-negative results were obtained when compared with research electron microscopy. Each specimen positive in research electron microscopy was positive in RIA, and six additional RIA positives were found from 58 electron microscopy negative specimens. A confirmatory test was necessary to find out marginally positive but nonspecific reactions in RIA. The developed radioimmunoassay is slightly more sensitive than research electron microscopy of unconcentrated stool specimens and considerably more sensitive and more specific than routine electron microscopy.

Child↗
PubMed1988

Electron microscopy of human immunodeficiency virus.

Two cell lines of human T lymphocytes (H9 and CEM) chronically infected with isolates of human or simian immunodeficiency viruses were examined by electron microscopy. Scanning electron microscopy of H9 cells showed characteristic morphological changes in the cells after infection with human T cell lymphotropic virus type III (HTLV-IIIB); these included loss of cell microvilli and their replacement by rounded surface protrusions. Virus particles were present over the whole cell surface, but were more numerous between, rather than on, surface protrusions. In contrast, CEM cells infected with three other isolates of the virus showed little change in morphology compared with uninfected cells; they typically had a single large aggregate of virus particles at the posterior end of the cell. Transmission electron microscopy of sections of infected cells showed budding virus in only a small proportion of cells although many had mature virus particles on their surface. The immature particles released by budding had a ring-like morphology in contrast to the mature virus with its characteristic elongated nucleoid. Surface spikes were rarely seen on sectioned virus particles, but were more obvious on the simian immunodeficiency virus than on human isolates. Negative staining of purified virus preparations showed that the peripheral dense material of immature particles had a striated structure. Surface spikes were not seen by negative staining on either immature or mature virus particles. A third type of smaller particle with surface spikes was found in all negatively stained preparations.

Animals↗
PubMed1982

Towards higher resolution in biomolecular electron microscopy.

Technical advances in electron microscopy have opened up exciting prospects to peer into the finest details of biomolecular organisation. Unfortunately, the potential of today's instruments cannot be fully exploited due to the intrinsic susceptibility of biological specimens to dehydration and electron irradiation. A survey is given of recent activities and trends aimed at overcoming these limitations.

Animals↗
PubMedDate not supplied

Dealing with particles in different conformational states by electron microscopy and image processing.

Electron microscopy and image processing are powerful tools for investigating different conformational states of enzymes. It is not always possible to isolate these often unstable intermediates as single species. As a result electron micrographs show a snapshot of enzymes in various conformational states. We describe here how to recognize that the imaged particles have different conformations and how to obtain for each species a three-dimensional model using single-particle image processing. We investigated the ATP synthase from chloroplasts, which has a molecular mass of about 550 kDa. It is a membrane-bound enzyme and consists of two segments, a membrane-embedded hydrophobic F(0) part and a hydrophilic F(1) part. Analysis of the particle images indicated that the molecules were in two different conformations. For both conformations three-dimensional models were calculated, which showed that the structures differed mainly in the tilt of the F(0) part with respect to the F(1) part.

Chloroplast Proton-Translocating ATPases↗