PubMed Health⌕ Search

SEARCH · PubMed Health

Results for “Microscopy, Electron”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6Linked to original sources
PubMed2000

Combining laser scanning confocal microscopy and electron microscopy to determine sites of synaptic contact between two identified neurons.

Here we report a double labelling method for correlative confocal and electron microscopy (EM) which allows selective characterisation of structural relationships between two single identified neurons in the same preparation. Using the lobster stomatogastric nervous system, we labelled pairs of identified, synaptically-connected neurons by intracellular injection of Lucifer Yellow (LY) in one neuron and a mixture of Rhodamine (Rdh) and Horseradish Peroxidase (HRP) in its partner. First, whole-mounts of LY- and Rdh-stained neurons were visualized using laser scanning confocal microscopy (LSCM) in order to isolate neuropilar regions of possible synaptic contact. Second, after conventional treatment for electron microscopy (LY was revealed with immunogold and HRP with DAB), areas of close appositions were viewed in EM. This technique allowed us to determine all the regions of close contact between two cells, and then to use electron microscopy to determine the presence or absence of synaptic contact within each of these restricted areas. These techniques enabled us to show that there were few areas of apposition and that only an extremely small proportion of these areas was in fact regions of synaptic contact between the two labelled neurons.

Animals↗
PubMed1995

Scanning electron microscopy-electron probe microanalysis study of the interface between apatite and wollastonite-containing glass-ceramic and rabbit tibia under load-bearing conditions after long-term implantation.

Glass-ceramic implants containing oxy- and fluoroapatite [Ca10(PO4)6(O, F2)] and beta-wollastonite (CaSiO3) were studied under load-bearing conditions in a segmental replacement model in the tibia of the rabbit. A 16-mm segment of the middle of the tibial shaft was resected at a point distal to the junction of the tibia and the fibula. The defect was replaced by a 15 mm-long hollow, cylindrical implant that was fixed by intramedullary nailing using Kirschner wire. The implants were 9 mm in diameter and 15 mm long bearing a central hole 3.05 mm in dianeter. The rabbits used were killed 6 months, 1 year, 18 months, and 2 years after implantation. The interface between the bone and the glass-ceramic was investigated by scanning electron microscopy-electron-probe microanalysis (SEM-EPMA). None of the glass-ceramic implants broke, and the glass-ceramic had bonded directly to the bone tissue without any intervening soft tissue. A calcium-phosphorus layer (Ca-P layer) was observed at the glass-ceramic/bone interface. This layer was 30-100 microns thick at 6 months after implantation, 60-110 microns thick at 1 year after implantation, 80-200 microns thick at 18 months, and 120-350 microns thick at 2 years. At the lateral surface of the glass-ceramic uncovered by the bone, the calcium-phosphorus layer was 50-80 microns thick at 6 months after implantation, 250-450 microns thick at 1 year, 300 approximately 400 microns thick at 18 months, and 300 microns thick at 2 years. The thickness of the calcium-phosphorus layer increased moderately after long-term implantation. However, it was difficult to estimate the rate of increase in the thickness of calcium-phosphorus layer.

Animals↗
PubMed2003

Extending the resolution of light microscopy and electron microscopy digitized images with reference to cellular changes after in vivo low oxygen exposure.

When processing frame-grabbed images from light microscopy (LM) and electron microscopy (EM), even a state-of-the-art digital camera is the weakest link between the microscope and the image processor. Details, which can be seen directly in the ocular at LM and in a negative recorded at EM, will not necessarily be represented in the frame-grabbed images. Because of this, there is a tendency to prefer a higher magnification at the expense of overview, i.e. only smaller areas are described. We find that the inadequacy of the camera can be overcome by taking multiple images of the same object, and align, expand, and add them into a more highly resolved image. At the LM level, the method has proved useful for describing the relation of the zinc pattern versus local in vivo oxygen measurements. At the EM level, we show that it is possible to achieve information about the spatial conditions in a given area, and the method may have applications on, e.g., visualization of ultra-small antibody-bound gold particles. The method can be performed on color and black and white images at any magnification and it has been tested in Adobe Photoshop (4.0 and higher) in WINDOWS 95, 98, and 2000.

Algorithms↗
PubMed1988

A scanning electron microscopy and electron probe X-ray microanalysis (SEM-EPMA) of pink teeth.

Samples of postmortem pink teeth were investigated by scanning electron microscopy and electron probe X-ray microanalysis. Fracture surfaces of the dentin in pink teeth were noticeably rough and revealed many more smaller dentinal tubules than those of the control white teeth. Electron probe X-ray microanalysis showed that the pink teeth contained iron which seemed to be derived from blood hemoglobin. The present study confirms that under the same circumstance red coloration of teeth may occur more easily in the teeth in which the dentin is less compact and contains more dentinal tubules.

Animals↗
PubMed1994

Scanning electron microscopy and electron probe microanalysis studies of human pineal concretions.

The calcareous concretions of human pineal bodies were investigated with scanning electron microscopy and electron probe microanalysis. The initial concretions measuring 5-7 microns in diameter may have started at the calcified pinealocytes. They grew appositionally forming concentric laminations, and then the simple calcospherulites over 20 microns occasionally aggregated with each other. Some of them became numerous spherulite-aggregated concretions. Others individually grew with scallop-shaped concentric laminations at intervals of 0.05-1 microns and became lobated calcospherulites up to 0.5 mm. The concretions over 0.5 mm were formed by their attachments. The major elements were Ca and P, while traces of S, Mg, and Na were detected. In the calcification and crystallization values, the center of the concretions over 50 microns was significantly higher than the periphery, while there were no differences among the centers and also among the peripheries. The Ca and P amounts in the center were 30.8% and 14.2% by weight and the Ca/P molar ratio was 1.68; thereby the sand-grain-shaped crystals may be nearly hydroxyapatite, as reported previously.

Aged↗
PubMed2004

Amyloidosis of Alzheimer's Abeta peptides: solid-state nuclear magnetic resonance, electron paramagnetic resonance, transmission electron microscopy, scanning transmission electron microscopy and atomic force microscopy studies.

Aggregation cascade for Alzheimer's amyloid-beta peptides, its relevance to neurotoxicity in the course of Alzheimer's disease and experimental methods useful for these studies are discussed. Details of the solid-phase peptide synthesis and sample preparation procedures for Alzheimer's beta-amyloid fibrils are given. Recent progress in obtaining structural constraints on Abeta-fibrils from solid-state NMR and scanning transmission electron microscopy (STEM) data is discussed. Polymorphism of amyloid fibrils and oligomers of the 'Arctic' mutant of Abeta(1-40) was studied by (1)H,(13)C solid-state NMR, transmission electron microscopy (TEM) and atomic force microscopy (AFM), and a real-time aggregation of different polymorphs of the peptide was observed with the aid of in situ AFM. Recent results on binding of Cu(II) ions and Al-citrate and Al-ATP complexes to amyloid fibrils, as studied by electron paramagnetic resonance (EPR) and solid-state (27)Al NMR techniques, are also presented.

Alzheimer Disease↗
PubMed1995

Scanning electron microscopy and transmission electron microscopy aspects of synergistic antitumor activity of vitamin C - vitamin K3 combinations against human prostatic carcinoma cells.

A MTT/formazan assay was used to evaluate the antitumor activity of vitamin C (Vit C), vitamin K3 (Vit K3), or vitamin C:vitamin K3 combinations against a human prostatic carcinoma cell line (DU145). Both Vit C and Vit K3 alone exhibited antitumor activity, but only at elevated doses. When Vit C and Vit K3 were combined at a C:K3 ratio of 100:1 and administered to the carcinoma cells, the 50% cytotoxic concentrations (CD50) of the vitamins decreased 10- to 60-fold. Subsequently, the DU145 cells were examined with transmission and scanning electron microscopy (TEM and SEM) following a 1 hour treatment with Vit C, Vit K3, or Vit C/K3 combined at their 50% cytotoxic dose. Our morphological data suggest that vitamin treatment with individual vitamins affects the cytoskeleton, the mitochondria, and other membranous components of the cell. Treatment with the vitamin combination appears to potentiate the effects of the individual vitamin treatment. Specifically, there are abundant necrotic cells. The surviving cells display morphological defects characteristic of cell injury.

Antineoplastic Agents↗
PubMed2001

Consecutive light microscopy, scanning-transmission electron microscopy and transmission electron microscopy of traumatic human brain oedema and ischaemic brain damage.

Cortical biopsies of 11 patients with traumatic brain oedema were consecutively studied by light microscopy (LM) using thick plastic sections, scanning-transmission electron microscopy ((S)TEM) using semithin plastic sections and transmission electron microscopy (TEM) using ultrathin sections. Samples were glutaraldehyde-osmium fixed and embedded in Araldite or Epon. Thick sections were stained with toluidine-blue for light microscopy. Semithin sections were examined unstained and uncoated for (S)TEM. Ultrathin sections were stained with uranyl and lead. Perivascular haemorrhages and perivascular extravasation of proteinaceous oedema fluid were observed in both moderate and severe oedema. Ischaemic pyramidal and non-pyramidal nerve cells appeared shrunken, electron dense and with enlargement of intracytoplasmic membrane compartment. Notably swollen astrocytes were observed in all samples examined. Glycogen-rich and glycogen-depleted astrocytes were identified in anoxic-ischaemic regions. Dark and hydropic satellite, interfascicular and perivascular oligodendrocytes were also found. The status spongiosus of severely oedematous brain parenchyma observed by LM and (S)TEM was correlated with the enlarged extracellular space and disrupted neuropil observed by TEM. The (S)TEM is recommended as a suitable technique for studying pathological processes in the central nervous system and as an informative adjunct to LM and TEM.

Adolescent↗
PubMedDate not supplied

High-resolution electron microscopy and electron tomography: resolution versus precision.

The performance of high-resolution electron microscopy and electron tomography is usually discussed in terms of two-point resolution, expressing the possibility of perceiving separately two image points of an object. However, the concept resolution obtains another meaning if one uses prior knowledge about the object and the imaging procedure in the form of a parametric model describing the expectations of the observations. The unknown parameters, such as the positions of the components in an object, can be measured quantitatively by fitting this model to the observations. Due to the statistical nature of the experiment, the resulting solutions for the positions of the components and therefore for the distance between the components will never be exact. An alternative to resolution is then the precision with which the distance can be measured. In the present paper, it is shown that the precision depends on the size of the components, the distance between the components, the resolution of the instrument, and the number of electron counts. For electron tomography, it also depends on the orientation of the object with respect to the rotation axis.

Image Processing, Computer-Assisted↗
PubMed2004

Analytical electron microscopy and electron holography on microstructures and magnetic domain structures of Sm-Co 2:17 magnets.

Microstructures and magnetic domain structures of precipitation-hardened Sm-Co permanent magnets were systematically investigated by analytical electron microscopy and electron holography. By an elemental mapping method with energy-dispersive X-ray spectroscopy, the change in the local distribution of additive elements, i.e. Cu, Fe and Zr, in Sm-Co magnets with various heat treatments was visualized and the enrichment of Zr in the Z-phase with a width of approximately 1 nm was clarified directly. Detailed analysis with electron holography revealed that considerable fluctuation in the distribution of lines of magnetic flux in the step-aged magnet was due to the chemical partitioning of additives and resulted in magnetic hardening during the magnetization process.

Holography↗
PubMed2003

Characterization of Co25Ag75 and (Co90Al10)28Ag72 granular films by electron diffraction, high-resolution transmission electron microscopy and electron spectroscopic imaging.

Series of sputter-deposited Co25Ag75 and (Co90Al10)28Ag72 giant-magnetoresistance granular films were characterized by electron diffraction, high-resolution transmission electron microscopy and electron spectroscopic imaging. Crystalline particles of fcc silver and hcp cobalt were detected in both thin-film systems before annealing. Annealing of (Co90Al10)28Ag72 films at 773 and 823 K yielded mixtures of fcc and hcp cobalt clusters and notably enlarged silver particles. In addition, crystallites of bcc Ag3Al were detected in the sample annealed at 823 K. The mesoscopic structure of the as-deposited films was investigated by dark-field imaging showing columnar growth-domains for silver. The columns were preserved during thermal treatment up to 773 K, whereas annealing at 823 K destroyed these domains.

Alloys↗
PubMed1989

Structural organization of the membrane-bound hydrogenase isolated from Alcaligenes eutrophus as revealed by electron microscopy.

Electron microscopy of negatively stained samples of the membrane-bound hydrogenase isolated from Alcaligenes eutrophus was used to obtain enzyme images with an estimated resolution of 2.5 nm. The two subunits with shapes similar to the letter 'U' making up the enzyme could be seen to be joined in two planes orthogonal to each other, making contact with their concave sides. In face-on view, the particle exhibited bilateral symmetry.

Alcaligenes↗
PubMed1987

Pitfalls of immunogold labeling: analysis by light microscopy, transmission electron microscopy, and photoelectron microscopy.

The immunogold method is widely used to localize, identify, and distinguish cellular antigens. There are, however, some pitfalls that can lead to nonspecific binding, particularly in cytoskeletal studies with gold probes prepared from small gold particles. We present a list of suggestions for minimizing nonspecific binding, with particular attention to two problems identified in this study. First, we find that the method used to prepare the colloidal gold particles affects the degree of nonspecific binding. Second, the standard BSA-stabilized small gold probes evidently possess exposed regions that bind to the proteins of cytoskeletal preparations. This was investigated in whole-mount cytoskeletal preparations of cultured cells by use of light microscopy, transmission electron microscopy, and photoelectron microscopy of silver-enhanced specimens. Gold probes were made from approximately 5-nm particles generated by reduction of HAuCl4 with three different reducing agents: white phosphorus, sodium borohydride, and citrate-tannic acid. All three preparations stabilized in the conventional way showed significant levels of nonspecific binding, which was highest with citrate-tannic acid. This problem was largely solved with all three types of probes by including fish gelatin in the probe buffer, by substituting fish gelatin for the BSA stabilizer used to prepare the probes, or by pre-adsorption methods. Application of these techniques resulted in clear immunogold labeling patterns with minimal nonspecific background.

Actins↗