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  • Natural Sciences in General  (267)
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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 5 (1987), S. 51-58 
    ISSN: 0741-0581
    Keywords: STEM image ; SE yield ; Digital image processing ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: An inexpensive, efficient device that supplies a transmission mode to the conventional SEM has been developed. The transmitted electrons strike a metal plate, and these generate secondary electrons that are proportional to the quantity of the transmitted electrons. The generated electrons are collected by the secondary electron detector. Hence, the performance of this device is influenced by the number of secondary electrons generated in the metal plate. In order to construct a device that can attain the best transmitted electron image, the signal-to-noise ratio of images, obtained from various trial devices, were measured by a newly-developed digital image processing program. When the material and shape of the device are selected, to produce high-secondary emission, the efficiency of the device compares with that of a relatively expensive standard detector system (scintillator detector).
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 5 (1987), S. 105-106 
    ISSN: 0741-0581
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 5 (1987), S. 109-110 
    ISSN: 0741-0581
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 5 (1987) 
    ISSN: 0741-0581
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 5 (1987), S. 159-169 
    ISSN: 0741-0581
    Keywords: Monolayer cells ; Microcarrier beads ; Transmission electron microscopy ; Scanning electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Cross-linked dextran beads provide an excellent surface for tissue-cultured cell monolayers, and can be processed for transmission (TEM) and scanning (SEM) electron microscopy, as well as light microscopy (LM). Cells are grown to confluency on the surface of the microcarriers, where at any point aliquots can be removed and experimentally treated as desired (e.g. immunocytochemistry) providing a representative sample. Sample preparation for TEM follows standard procedures for any cell monolayer, but infiltration times must be at least doubled to allow penetration of the beads. The polymerized blocks can then be sectioned for TEM or LM with no additional steps required. SEM sample preparation involves attaching the fixed bead/cell suspension to a glass coverslip with poly-1-lysine, dehydration, critical point drying, and coating for conductivity. The fixed and dried sample can also be attached directly to the SEM stub as free beads and subsequently gold coated. These beads provide (1) an increased surface area of cells visible per area of thin section, (2) eliminates the careful orientation required for flat substrate methods of embedding, (3) decreases the amount of sample manipulation in the forms of re-embedding and gluing, and (4) decreases the amount of drying artifact seen as cracking in SEM monolayer preparations.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 5 (1987), S. 211-215 
    ISSN: 0741-0581
    Keywords: Photography ; Developer ; CBED ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The use of a surface developer, pyrocatechol, to process transmission electron microscope negatives has been shown to have significant advantages over the conventional D-19 process. The process described here is tolerant of a large margin of error in the electron exposure and produces a negative that not only retains details both in the highlight as well as the faint regions, but also preserves local contrast. These characteristics are particularly useful in convergent beam electron diffraction applications where one encounters a wide contrast range. Improved acuteness and an enhanced signal to noise ratio due to the prolonged exposures associated with this process have also been observed.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 5 (1987) 
    ISSN: 0741-0581
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 5 (1987), S. i 
    ISSN: 0741-0581
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 5 (1987), S. 303-314 
    ISSN: 0741-0581
    Keywords: Immunocytochemistry ; Retina ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: We have developed a protocol for post-embedding immunoelectron microscopy that utilizes uranyl acetate, en bloc, as a secondary tissue fixative. Squirrel and cat retinas were fixed in 1% paraformaldehyde-1% glutaraldehyde for one hour. Secondary fixation was by 2% uranyl acetate, en bloc, (1 hour) during tissue dehydration. The tissue was embedded in LR White or Lowicryl K4M resin. Post-embedding immunoelectron microscopy (indirect immunogold) was performed on thin sections with antibodies to four different classes of proteins (filamentous, cytoplasmic, membrane, and extracellular matrix). The sections were then stained sequentially on drops of uranyl acetate and lead citrate, and by vapors of osmium tetroxide. Uranyl acetate fixation and/or staining of the sections by osmium tetroxide was omitted from the control experiments. Differences after secondary fixation with uranyl acetate and staining of the thin sections with osmium tetroxide were better overall preservation and enhanced contrast of the extracellular matrix, membranes, cytoplasm, and DNA. Antigenicity, as evidenced by the immunolabeling of the four proteins, was retained. Quantitation of the immunolabeling for the cytoplasmic and membrane proteins revealed significantly increased labeling densities in tissue postfixed with uranyl acetate. The improved tissue preservation and immunolabeling of proteins indicate that secondary fixation with uranyl acetate can be a valuable addition to post-embedding immunocytochemistry.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 6 (1987), S. 63-79 
    ISSN: 0741-0581
    Keywords: Plastic flow ; Section surface relief ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The technology of ultramicrotomy is now well established, but the properties of the resin that determine the different forces needed to generate a section have been neglected, although this process could introduce artefacts in the thin sections. We have investigated the principal resin dependent factors involved in the sectioning process and determined the related mechanical properties. Tensile experiments have given the best correlation with the sectioning quality of the resin: the elastic (Young's) modulus value (depending on polymer structure or hardening mode), the presence of a short plastic flow for a controlled fracture and enough flexibility to minimize shearing, and internal cracks, appear to be the main characteristic parameters. The ultrathin section seems to be generated by a process close to cleavage, favoured by the relative hardness of the embedding media, while machining and “true” sectioning requires softer resins.Consequently, the rupture follows the path of least resistance in the specimen-resin composite, providing sections with a surface relief. Embedded biological material copolymerizes with polycondensed matrix (epoxy resins), and, by reducing the heterogeneity, gives smoother sections. Embedments hardened by radical polymerization provide a rougher relief, since almost no copolymerization occurs, offering to the microtome a heterogeneous block with two constituents of very different mechanical properties. The surface relief seems to be an important factor in labelling, staining, and imaging, and more attention has to be paid for some improvements of the quality of the information provided by electron microscopy.
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  • 11
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 6 (1987), S. 167-173 
    ISSN: 0741-0581
    Keywords: Microtubules ; Actin filaments ; Aster motility ; Micro-filamentous and microtubular networks ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: This paper summarizes observations on the motility and behavior of microtubule asters in polymorphonuclear leukocytes under a variety of experimental conditions. These observations suggest that the location and organization of microtubules is influenced, at least in part, by the activity of the cortical actin network. Aster motility may therefore serve as an indicator of the interaction between the centrosomal microtubules and the cell cortex, and it is speculated that this interaction is of importance for leukocyte translocation.
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  • 12
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 6 (1987), S. 175-183 
    ISSN: 0741-0581
    Keywords: HVEM ; Synaptic transmission ; Synapses ; Neurons ; Immunocytochemistry ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: There is a need for an electron microscopic method for visualization of selectively stained neurons and neuronal processes with higher resolution than can be obtained with the light microscope, but using thick sections that allow visualization of the three-dimensional structure of the neuron. Such a method is required for measurement of the geometry of neurons, and this information is needed to test theoretical predictions on the way in which electrical signals of synaptic origin are processed by the cells. The high voltage electron microscope (HVEM) is well suited to this application, because of its high resolution and ability to form images of thick sections. Use of this instrument requires development of selective stains that can produce diffuse cytoplasmic staining of specific cells or cell populations on the basis of their functional properties. Several such methods currently being employed for light microscopic work can be used directly in the high voltage electron microscope or can be made useful by relatively minor alterations. These include intracellular staining with horseradish peroxidase, axonal tracing with Phaseolus vulgaris leukoagglutinin (PHA-L), and immunocytochemical staining for specific cell markers known to stain the cytoplasm of certain cell populations.Cells stained intracellularly by microinjection of horseradish peroxidase during physiological recording experiments may be stained in thick (ca. 50 μm) sections cut on a vibratome or similar instrument and stained in the standard way, using methods designed for light microscopy. The sections are then postfixed in osmium tetroxide and embedded in epoxy plastic. Sections cut from these blocks at thicknesses of from 1 to 5 μm using a dry glass knife may be examined directly in the HVEM with no further staining. This produces a very clear image of the cell on a relatively unstained background. This method provides more than adequate resolution of the boundary of the neuron, allowing measurement of neuronal processes to better than 10-nm precision.Similar results are obtained when the same method is applied to axonal tracing using PHA-L. In this case, the exogenously applied marker is used to label a small population of nearby neurons and to trace their connections with other cells at a distance. The lectin is detected by immunocytochemistry, but the selective contrast of the image is adjustable because the concentration of antigen in the cell is largely controlled by the experimenter. The lectin is distributed diffusely in the cytoplasm in a pattern identical to that of intracellular staining, so like intracellular staining, it reveals the overall shape of the cell.Immunocytochemical labelling using endogenous antigens known to be distributed in the cytoplasm of specific neurons produced inadequate control of selective contrast when prepared in this manner. Instead, 1-10μm sections cut from blocks of nervous tissue were embedded in polyethylene glycol, stained using a combedded in polyethylene glycol, stained using a combination of immunocytochemistry and histochemical intensification methods, and embedded in plastic on the grid. This method, which is also suited for staining with poorly penetrating markers such as colloidal gold, may also prove useful in a variety of other situations requiring the intensification of selective contrast.
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  • 13
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 6 (1987) 
    ISSN: 0741-0581
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
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  • 14
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 6 (1987), S. 305-306 
    ISSN: 0741-0581
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
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  • 15
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 6 (1987), S. 309-310 
    ISSN: 0741-0581
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
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  • 16
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 6 (1987), S. 357-366 
    ISSN: 0741-0581
    Keywords: Electron microscopy ; Immunolabeling ; Skeletal muscle ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Immunoelectron microscopy techniques were used to localize alpha-actinin within the Z lattice of adult skeletal muscles. Analysis of electron micrographs by direct visualization demonstrated that anti-alpha-actinin Fab fragments bound throughout the Z lattice. A low-resolution scanning densitometry technique was developed to quantitate the visual increase in the density of the Z lattice. These techniques did not allow determination of the particular component of the Z lattice, amorphous matrix, axial filaments, or cross-connecting filaments with which the antibody was associated. Therefore, additional techniques, including direct measurement of filament diameters and optical diffraction, were utilized in determining which components of the Z lattice bound anti-alpha-actinin Fab fragments. These analyses suggest that the antibody binding is distributed evenly throughout the lattice, along the filaments, and between them and is confined to the region of double overlap of the ends of the thin filaments.
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  • 17
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 7 (1987), S. 29-33 
    ISSN: 0741-0581
    Keywords: Specimen preparation ; Negative staining ; Freeze-drying/metal-shadowing ; Biological electron microscopy ; Specimen adsorption ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: We describe the design, construction, and operation of a simple glow discharge unit that can be used to make surfaces such as carbon-coated electron microscopy grids and glass coverslips hydrophilic. The use of a vacuum leak detector (Tesla coil) in place of a conventional high-voltage power supply and a small plastic desiccator for the vacuum chamber make the unit very inexpensive. Owing to the small volume of the chamber and the simplicity of the unit, the whole glow discharge process can be carried out in only 2 to 3 min, a time considerably shorter than that required for conventional vacuum evaporators. The hydrophilic surface improves adsorption of particles by several orders of magnitude in preparation for negative staining, freeze-drying, and other procedures.
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  • 18
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 7 (1987), S. 53-60 
    ISSN: 0741-0581
    Keywords: Montage ; Collage ; Display ; Photographic technique ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The preparation of overlapping electron micrographs (particularly from transmission electron microscopy) requires special forethought in planning, exceptional skills in microscopy and photographic techniques, as well as in display preparations which are unique in their handling and execution. In this report, step-by-step instructions are given on specimen preparation, micrography, darkroom printing, and mounting for montage display purposes.
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  • 19
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 7 (1987), S. 85-89 
    ISSN: 0741-0581
    Keywords: Gap junctions ; Amphibia ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: By electron microscopic observations of freeze-etching replicas, the gap junctions of ectoderm cells of early gastrulae of Xenopus leavis, injected with antibodies against gap-junction protein at an earlier stage, were compared with those of normal gastrulae. Most of the gap junctions found in the antibody-injected series were of very small size and consisted of fewer than 40 connexons, while those of the normal gastrulae usually have gap junctions with over 100 connexons. It was concluded that the normal assembly of intramembranous particles to form gap junctions was attenuated by microinjection of the antibodies.
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  • 20
    ISSN: 0741-0581
    Keywords: Goat poxvirus ; Bovine rhinotracheitis virus ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: We studied the morphology and morphogenesis of viral envelopes and nucleocapsids of goat poxvirus (GPV) and infectious bovine rhinotracheitis virus (IBRV) by means of the freeze-fracture technique. The GPV at an early development stage was fractured in its middle, and the envelope was shown to be a bilayer of particles. The mature GPV was fractured between two monolayers of the envelope. These facts suggest that there is little lipid and mainly protein particles in the envelope at the early-development stage, then the lipid inserts into the envelope during viral development. We found that there were still many intramembranous protein particles in protoplasmic fracture face (PF) and extracellular fracture face (EF) of the envelope of mature GPV in the cytoplasm, and fewer particles in the envelope of released GPV. In the envelope of mature IBRV, however, there were many more intramembrane protein particles in the PF face than that in the EF face. Spike-like structures could be seen at the outer edge of the IBRV envelope at times. Protein particles were regularly arranged in the plasmic membranes contacting IBRV. This phenomenon seems to be related to IBRV release. The naked cores, empty capsids, and nucleocapsids of IBRV were assembled in the nucleus of infected cells at the same time. The assembled nucleocapsids could be divided into five types according to their different fracturing positions, whose morphology was observed after deep etching. The morphology of the samples prepared with different methods was compared as well.
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  • 21
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 7 (1987), S. 131-148 
    ISSN: 0741-0581
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
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  • 22
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 7 (1987), S. 167-175 
    ISSN: 0741-0581
    Keywords: Morphometry ; Organelle arrangement ; Exocrine glands ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Currently available morphometric methods provide useful information on the three-dimensional properties (such as volume, surface, etc.) of biological structures. These methods, however, do not reveal how the same structures are spatially organized within the cell. A sum of problems, which concern mainly the definition of shape and location of the sectioned structures, does not allow the three-dimensional representation of the organelle arrangement from a quantitative analysis of sections. Following a different approach, this study considers the topographic relationship between ten distinct subcellular structures: nucleus, Golgi, ribosomes, mitochondria, lysosomes, lipid droplets, secretory granules, and apical, lateral, and basal plasmalemma. The analysis of associations from 2 × 2 tables calculated for each pair of structures and the pattern of multiple associations obtained by clustering methods provide a useful description of the spatial relationship among different cell compartments. The results of the investigation carried out in parallel on seven human exocrine glands (pancreas, parotid gland, submandibular gland, lacrimal gland, ceruminous gland, ampulla of the vas deferens, and seminal vesicle) allow an immediate evaluation of the method and a comparative analysis of the cytologic organization of secreting cells of human exocrine glands.
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  • 23
    ISSN: 0741-0581
    Keywords: Autoradiography ; Image processing ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: EMAMAP is a program for the data acquisition phase of maximum-likelihood analysis of electron microscope autoradiographs. This program is written in C and has been implemented on a Masscomp MC-500 which supports a graphics processor and a digitizing tablet. The image analysis is automated at a low level: the program operator outlines the edges of the structures of interest using the digitizing tablet, while contiguous regions formed by closed contours are automatically filled by the software. The resulting image is compressed for efficient storage by a quadtree encoding technique for which data compression ratios of greater than 25:1 have been achieved. In practical terms this implies that the data from a typical experiment of 50 autoradiographs could be stored on a single floppy disk. The system is currently in use for acquiring actual biological experimental data.
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  • 24
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 7 (1987), S. 223-231 
    ISSN: 0741-0581
    Keywords: Nuclear chromatin ; 20-30 nm fiber loops ; Detergent-lysed cells ; Joy® ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: A method for electron microscopic demonstration of supranucleosomal (20-30 nm chromatin) fiber loops was developed. Chicken erythrocytes were treated with varying concentrations of detergents, such as Joy®, sodium N-lauroyl sarcosinate, and sodium laurylsulfate, and then fixed with a formalin solution. The fixed cells were centrifuged onto an electron microscope grid, followed by staining and metal shadowing. Thin-sectioned specimens of the fixed cells were prepared routinely. Although supranucleosomal fiber loops could be observed when any one of these detergents was used, Joy gave the best result. Electron micrographs of rotary-shadowed specimens of erythrocyte ghosts formed by treatment with a low concentration (0.07-0.11 w/w%) of Joy showed a halolike, radial arrangement of supranucleosomal fiber loops around the ghost cells. The width of the halo was about 3μm. By increasing the detergent concentration (∼0.18% Joy), nucleosome fibers and naked DNA appeared and increased in number, indicating that the supranucleosomal fibers were disassembled by the action of the detergent. Thin-sectioned specimens of cells treated with 0.09% Joy showed granulofibrillar chromatin radially dispersed from the nuclear cage. The fibers were thought to be identical with the supranucleosomal fibers observed in the rotary-shadowed specimens.
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  • 25
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    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 8 (1988), S. 115-131 
    ISSN: 0741-0581
    Keywords: Electron microscopy ; Fungal diagnosis ; Fungal therapy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Defects in cell-mediated immunity caused by infection with the human immunodeficiency virus (HIV) render AIDS patients particularly susceptible to fungal pathogens. Signs and symptoms of serious infection may be nonspecific, and early diagnosis and institution of antifungal therapy is essential to decrease morbidity and mortality in this patient population. In a symptomatic individual, invasive procedures are often required to establish a microbiologic diagnosis, and histopathologic examination of tissue by light and electron microscopy is often the first indication of a serious fungal infection in an AIDS patient.
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  • 26
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    Journal of Electron Microscopy Technique 8 (1988), S. 193-200 
    ISSN: 0741-0581
    Keywords: Thickness measurement ; Electron energy-loss spectroscopy (EELS) ; Inelastic mean free path ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: We discuss measurement of the local thickness t of a transmission microscope specimen from the log-ratio formula t = λ In (It/I0) where It and I0 are the total and zero-loss areas under the electron-energy loss spectrum. We have measured the total inelastic mean free path λ in 11 materials of varying atomic number Z and have parameterized the results in the form λ = 106F (E0/Em)/ln (2βE0/Em) where F = (1 + E0/1,022)/(1 + E0/511)2, the incident energy E0 is in keV, the spectrum collection semiangle β is in mrad, and Em = 7.6Z0.36. This formulation should allow absolute thickness to be determined to an accuracy of ±20% in most inorganic specimens.
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  • 27
    Electronic Resource
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    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 5 (1987), S. 91-103 
    ISSN: 0741-0581
    Keywords: Scanning electron acoustic microscopy ; Thermal wave microscopy ; Subsurface imaging ; Composites ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Scanning electron acoustic microscopy is a new technique for imaging the thermal and elastic properties of surfaces and detecting subsurface flaws. It can be carried out in a modified scanning electron microscope. The effects of electron beam energy and phase angle on scanning electron acoustic images of the thermal and elastic properties of surfaces were studied with an alumina fiber/aluminum matrix composite for fiber directions both transverse and coaxial to the surface. Images produced with 10- and 30-keV electrons at beam modulation frequencies of 80-1200 kHz appeared to be identical, with the exception of a lower signal-to-noise ratio for the lower electron energy. This observation suggests that the energy input from the beam can be considered to occur at the surface for electron energies below 30 keV and frequencies below 1200 kHz. Images recorded at 0° phase angle mapped regions of different thermal and elastic properties. Images recorded at 90° phase angle highlighted the boundaries between such regions. Scanning electron acoustic microscopy can image features of different thermal and elastic properties at greater depth than traditional imaging with backscattered electrons. The practical application of the technique to the study of surfaces is illustrated by the imaging of grain structure and subsurface particles for an extruder barrel.
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  • 28
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    Journal of Electron Microscopy Technique 8 (1988), S. 273-284 
    ISSN: 0741-0581
    Keywords: Superconductors ; Electron microscopy ; Perovskites ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: High-resolution transmission electron microscopes operating at 300 and 400 kV were used to investigate the crystallography and microstructure of the perovskitelike YBa2Cu3O7-x. In this paper, we evaluate the performance attainable with these microscopes both empirically and by computer modelling. Based upon the assumption that oxygen may be a key to superconductivity properties, we have also investigated the visibility of the oxygen sites as well as the heavier yttrium and barium ion positions and the lighter Cu atom positions. We propose a scheme for observing different twin orientations in these structures and hence the oxygen atom positions seen in projection for the [100] and [010].Our observations of both thick and thin regions of Y-Ba-Cu-O materials are reported as well as the problems of adjusting microscope parameters and specimen alignment to obtain interpretable images. We also give a preliminary report on the effects of heat treatment as seen in high-resolution micrographs to assess disorder of the heavy atoms and oxygen vacancies.
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  • 29
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    Journal of Electron Microscopy Technique 5 (1987), S. 171-179 
    ISSN: 0741-0581
    Keywords: Dow latex ; Internal standards ; Electron microscope magnification ; calibration ; Latex sphere instability ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: In the early days of electron microscopy polystyrene latex particles were used as magnification standards. But in contrast to optical diffraction grating replicas made with carbon or SiO with precise line spacings resistant to electron irradiation, the latex spheres undergo changes, and conflicting reports have created some confusion. We used a highly stabilized electron microscope with controlled unchanging objective current in contamination-free conditions to expose standard Dow latex spheres of 0.399 μm (±0,0060 μm) under defined electron beam conditions. We measured the direct intensity of the electron current impinging on the screen. Removing the object from the beam, it is possible to measure the quantity of electrons absorbed by the latex spheres, expressed in nA/μ2. We used two standard intensities: a low intensity with widespread beam, equivalent to a 2-sec exposure time on Kodak electron image plates, and a higher intensity, obtained by increasing Condenser II current (two coarse plots towards crossover) that gives rise to a brightly illuminated observation screen. This is equivalent to a 1-sec exposure time on the same type of plates. It could be shown that all polystyrene particles uniformly decrease in size. This loss of material manifests itself immediately after the start of irradiation. The decrease follows a hyperbolic curve and reaches values of 14.35% size decrease for low radiation intensity after 15 min. An even greater decrease (namely 16.08% size decrease) was found for medium intensity electron bombardment. Sandwiching the particles with thin carbon film has no protective effect. Particle size has been determined on the photographic plates by measuring the shadow cast by 30° angle platinum shadowing and the shrinking particle itself. Particles “shadowed” with an angle 90° permit us to measure the annular concentric “shadow” once the spheres initiate shrinking.
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    Journal of Electron Microscopy Technique 5 (1987), S. 203-209 
    ISSN: 0741-0581
    Keywords: Transmission electron micrograph ; Contrast enhancement ; Bas-relief ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Two methods for bas-relief electron micrographs are described, one to produce transparencies for projection and one to produce prints for publication. The basis of these methods is a controlled misregistration of a positive image and a negative image, both on film, to increase contrast and produce a “bas-relief” effect. This gives the final image a three-dimensional appearance. No apparent loss of resolution results and no artificial amendment is required. To produce transparencies, a contact film positive is produced from the negative and the two are sandwiched in a slide mount with the appropriate amount of lateral displacement to give the effect. To produce prints, the film positive and the film negative are used to sequentially expose the same sheet of photographic paper prior to development to realize the effect. The bas-relief induced by the misregistration of the film plates causes apparent shadows and highlights that produce the apparent height that is seen in the enhanced images.
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    Journal of Electron Microscopy Technique 5 (1987), S. 221-221 
    ISSN: 0741-0581
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 32
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    Journal of Electron Microscopy Technique 5 (1987), S. 249-261 
    ISSN: 0741-0581
    Keywords: Specimen preparation ; Three-dimensional image ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The application of the conventional double-fixation method (glutaraldehyde and osmium tetroxide) to whole yeast cells is difficult because the thick cell wall of the yeast prevents the penetration of osmium tetroxide. However, this problem was solved by using the freeze-substitution fixation method. Therefore, it was possible to examine the intracellular structures of the yeast cells without digestion of the cell wall. In the present method, specimens for transmission electron microscopy and for scanning electron microscopy were prepared simultaneously. By scanning electron microscopic observation, three-dimensional information about internal structures was obtained. In the cytological analysis of the yeasts, intracellular structures were well preserved by using the freeze-substitution fixation method. On the outer leaflet of the nuclear envelope, many ribosomes were attached. The rough endoplasmic reticulum and Golgi apparatus were clearly seen in the yeast cytoplasm. The Golgi stack appeared to consist of smooth membranes, and small vesicles were present beside it. The details of other structures such as the nuclear division apparatus, actinlike filaments, and viruslike particles were also revealed. The present technique can be applied to most species of yeast cells. With this new information, the previous model of a yeast cell was modified.
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  • 33
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    Journal of Electron Microscopy Technique 9 (1988), S. 283-291 
    ISSN: 0741-0581
    Keywords: Ultrastructure ; Kidney ; Artifacts ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The aim of this presentation is to draw attention to the problems inherent in evaluating the ultrastructure of percutaneous renal biopsies and to discuss some of the special techniques which are useful in this area. It is important to realize that the ultrastructure as it appears in this kind of material does not necessarily reflect conditions in vivo. Comparison with suitable reference material may, however, permit reliable conclusions in terms of pathological diagnosis and pathogenesis. It is advocated that purely qualitative methods, which until now have predominated in ultrastructure work with renal biopsies, be replaced by morphometry and semiquantitative methods when it is possible and practical to do so in any research situation.
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    Journal of Electron Microscopy Technique 6 (1987), S. 1-6 
    ISSN: 0741-0581
    Keywords: Residual ; Asbestos fibers ; Ferruginous bodies ; Amosite worker ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: A recurring question that concerns researchers who use digestion techniques for the electron microscopic study of asbestos and ferruginous body (FB) load in tissue is: “Do appreciable numbers of the total fibers or FBs remain adhered to the walls of preparative vials after digestion?”A test series was devised to evaluate the fiber and FB content remaining in digestion vials (glass or plastic) as well as the effectiveness of removing these particulates through variations in the rinsing procedure. The material used for all studies was digested lung tissue from a former amosite asbestos worker. The digestion procedure was based on the bleach technique of Smith and Naylor (Am. J. Clin. Pathol.: 58:250-54, 1972), as modified by Williams et al. (J. Toxicol. Environ. Health:10:627-628, 1982). Aliquots (1.5 ml) of the digests were used to create reproducible standards. These were placed in either the clean glass or polystyrene vials that had been cut to fit in an AMRAY 1000A scanning microscope interfaced with an X-ray energy dispersive analysis system. The aliquots were allowed to remain in the vials for 10 min or 24 h before rinsing was initiated. Aliquots used for the glass vials contained 5.1 × 106 fibers and 20 × 103 FBs, while aliquots for the polystyrene vials contained 6.9 × 106 fibers and 64 × 103 FBs.The maximum errors encountered for the glass and polystyrene vials were, respectively, 0.094% and 0.12% for fibers and 0.0098% and 0.0084% for FBs and are considered small when compared with potential sources for errors in the other stages of the preparative techniques. Also, it was concluded that if at least three thorough rinses are applied, the loss was minimal in either the glass or polystyrene vials.
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    Journal of Electron Microscopy Technique 6 (1987), S. 131-141 
    ISSN: 0741-0581
    Keywords: Skeletal muscle ; Myofibrils ; Fish ; Electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: We have studied the structure of the M band in fish skeletal muscle using thin sectioning and deep-etching rotary shadowing. A reconstruction of the M band from these images shows it to be formed by obliquely arranged struts, which join the thick filaments to each other. Thickening of the thick filaments' profiles and nodal points where the struts cross each other are responsible for the fine sublines visible in longitudinal sections of the M band region.
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    Journal of Electron Microscopy Technique 6 (1987), S. 193-205 
    ISSN: 0741-0581
    Keywords: HVEM ; EM ; Three-dimensional reconstruction ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The methodology is described, as developed at the Albany NIH Biotechnological High Voltage Electron Microscope Resource, for the three-dimensional reconstruction of objects in thick sections. The reconstructions are obtained from projection sets which are recorded by high voltage electron microscopy. The different steps of the procedure are illustrated in detail, using the cilium reconstruction as an example.
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    Journal of Electron Microscopy Technique 6 (1987), S. 231-235 
    ISSN: 0741-0581
    Keywords: Immunoelectron microscopy ; Cryoultramicrotomy ; Monoclonal antibodies ; Striated muscle ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: A systematic approach to the discovery of new proteins of ultrastructural interest is discussed. It involves the merging of monoclonal antibody technology with immunocytochemical technology, particularly immunoelectron microscopy. In this approach, monoclonal antibodies are raised to a cellular preparation that can be grossly heterogeneous in its protein composition. The hybridoma culture fluids are screened by immunocytochemistry for the ultrastructural localization of their antibodies. Those monoclonal antibodies that show specific ultrastructural localizations of interest are then selected for further investigation. The antigen to which a given monoclonal antibody is directed is then identified by immunoprecipitation and immunoblotting with that antibody. By this approach, two new striated muscle proteins of ultrastructural interest have been discovered and are named zeugmatin and enactin. The former is a protein of over 500 kD localized by immunoelectron microscopy to the Z-bands, the latter of 245 kD localized to the N1 line of striated muscle.
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    Journal of Electron Microscopy Technique 6 (1987), S. 307-308 
    ISSN: 0741-0581
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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    Journal of Electron Microscopy Technique 6 (1987), S. 315-316 
    ISSN: 0741-0581
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 40
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    Journal of Electron Microscopy Technique 6 (1987), S. 335-348 
    ISSN: 0741-0581
    Keywords: Digestive techniques ; Vascular elastic networks ; SEM ; Blood vessels ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Two digestion procedures are now available to expose and isolate networks of vascular elastic fibers for three-dimensional SEM observation. This study was designed to observe and elucidate the differences between the two types of digestion (sodium hydroxide vs. formic acid) and the differences between the two types of dehydration (ethanol-critical-point drying vs. freeze drying) used in each procedure. Canine venous valve segments, containing delicate networks of elastic fibers, and femoral arteries, containing large elastic lamellae, were used to compare the effects of the digestion and dehydration procedures on two types of vessels with different content and organization of elastic tissue. Results indicated there was no significant difference in the architecture of the elastic networks of either vessel based on the method of digestion. The major architectural changes in the elastic networks occurred as a result of the dehydration procedure used following digestion. Freeze drying is probably the best for arterial specimens due to their prominent lamellae, which give added support to maintain their normal architecture. It is suggested that both methods of dehydration be used on corresponding venous specimens containing delicate elastic networks. In this way, the investigator can benefit from the advantages of each method and overcome their respective disadvantages to get a more accurate picture of the three-dimensional architecture of these delicate networks.
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  • 41
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    Journal of Electron Microscopy Technique 6 (1987), S. 367-376 
    ISSN: 0741-0581
    Keywords: Stacking faults ; Dynamical theory calculations ; Digital image processing ; Weak beam images ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: An analysis of the effects of strain and surface roughness on the contrast of weak beam images of small metallic particles is carried out. in order to study these effects, theoretical calculations of the intensity obtained in wedge-shaped bent gold crystals were performed. These calculations were based on the standard form (Bethe's approach) of the dynamical theory. The theoretical results were compared with weak beam experimental images of gold particles. It was found that the image contrast obtained in thin crystalline regions is not sensitive to strain. Therefore, intensity variations experimentally obtained in these regions seem more likely to be related to the surface roughness of the crystalline specimen. We also studied (experimentally and theoretically) the image-contrast characteristics of stacking faults in small particles. The comparison between the experimental micrographs and the theoretical images suggests a possible model of the small particle shape. This model seems to explain most of the experimentally observed image-contrast characteristics.
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  • 42
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    Journal of Electron Microscopy Technique 7 (1987), S. 1-16 
    ISSN: 0741-0581
    Keywords: External determinants ; Colloidal gold ; High-voltage electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Conventional freeze-fracture techniques were combined with immunogold labeling and with plastic embedding and sectioning to analyze the distribution of membrane immunoglobulins (mIgs) and their associated intramembrane particles (IMPs) in E-face replicas of murine B-lymphocyte plasma membranes. Immunogold labels were applied to cells after the process of freeze-fracture and replication. Conventional stereoscopic transmission electron microscopic examination of sectioned, labeled replicas (SLRs) revealed that the gold-labeled mIgs were bound to and localized on the outer leaflets of split and replicated membranes. The gold labels were attached to the external determinants of the mIg molecules, which were retained beneath and contiguous with the replicated E-faces. The mIgs were also localized on the external surface of unreplicated microvilli. In addition, thick sections examined by high-voltage transmission electron microscopy (HVEM) revealed large expanses of replica with well-resolved IMPs. mIgs colocalized with small-diameter (〈60 Å) IMPs in E-face replicas of B-lymphocytes whose mIgs were patched by anti-immunoglobulin. Thus, postreplication E-surface labeling of split and replicated membranes is a high-resolution technique that is suitable for the study of membrane protein distribution in E-face replicas and contiguous nonreplicated tissue.
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  • 43
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    Journal of Electron Microscopy Technique 7 (1987), S. 319-322 
    ISSN: 0741-0581
    Keywords: Cross-sectional transmission electron microscopy (XTEM) ; LSI circuit ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Cross-sectional transmission electron microscopy (XTEM) has been used to diagnose silicon LSI circuits and Josephson junction devices. For LSI circuits, some typical failure problems have been presented. For Nb-Si-Nb Josephson junction, microholes in the thin silicon layer have observed, and they are responsible for the short circuiting of these devices.
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  • 44
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    Journal of Electron Microscopy Technique 8 (1988), S. 1-1 
    ISSN: 0741-0581
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 45
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    Journal of Electron Microscopy Technique 8 (1988), S. 105-113 
    ISSN: 0741-0581
    Keywords: Electron microscopy ; Histopathology ; Mycobacterium diagnosis ; Mycobacterium therapy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: This reviw examines an important bacterial infection in acquired immunodeficiency syndrome (AIDS). Despite occasional infections with bacteria such as Streptococcus pneumoniae, Haemophilus influenzae, Salmonella, and Nocardia in patients with AIDS, the primary problems of AIDS and invading bacterial infections center around mycobacteropsos. A unique feature of AIDS has been the common identification of disseminated infections with Mycobacterium avium-intracellulare. The following discussion examines our present understading of this group of organisms and how they interact with the compromised host.
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    Journal of Electron Microscopy Technique 5 (1987), S. 1-15 
    ISSN: 0741-0581
    Keywords: Lowicryl K4M ; Smooth muscle ; Specimen preparation ; Cryofixation ; Lyophilization ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The techniques of quick freezing and freeze-drying provide an alternative to the more classical methodologies of chemical fixation and dehydration with organic solvents. It is possible to embed freeze-dried tissue in low viscosity resins, either at room temperature or at subzero temperatures in Spurr's resin or Lowicryl K4M, respectively. The choice of embedding medium affords additional flexibility in postdrying and embedding conditions, since Spurr's resin allows vapor fixation with osmium tetroxide and thermal polymerization. Osmium tetroxide is not recommended for Lowicryl resins, but these media permit polymerization at subzero temperatures with ultraviolet light. Both resins have unique advantages that may be utilized, depending upon the purpose of the embedding.In this paper, we discuss the details of preparing smooth muscle, from rabbit renal artery, by quick freezing and freeze-drying, as well as methods for the embedding of the freeze-dried tissue in both Spurr's resin and Lowicryl K4M. Although we have previously reported the ultrastructure of smooth muscle embedded in Spurr's low viscosity resin, the combination of freeze-drying and infiltration in Lowicryl K4M represents a new approach that allows the elimination of chemical fixation, dehydration with organic solvents, and heat polymerization of the embedding medium.
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    Journal of Electron Microscopy Technique 5 (1987), S. 75-80 
    ISSN: 0741-0581
    Keywords: Calibration ; Focusing steps ; Rotation ; Reflection electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Reflection electron microscopy (REM) is used to calibrate the focusing steps and rotation of electron microscopes. The calibration of focusing steps is done by the direct measurement of the shift on in-focus positions in the REM micrographs. Rotations between the diffraction patterns and images are calibrated in the usual way. By using the REM geometry, the reflection high energy electron diffraction (RHEED) patterns and REM images have no rotation symmetry, thus eliminating the 180° uncertainty.
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    Journal of Electron Microscopy Technique 5 (1987), S. 107-108 
    ISSN: 0741-0581
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
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    Journal of Electron Microscopy Technique 5 (1987), S. 113-114 
    ISSN: 0741-0581
    Keywords: TEM sample preparation ; palladium silicide ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
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    Journal of Electron Microscopy Technique 5 (1987), S. 141-151 
    ISSN: 0741-0581
    Keywords: Helical reconstruction ; Computer modeling ; Particle distortion ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: We have studied the manner in which real-space reconstructions of helical particles are affected by particle distortions commonly present in electron micrographs. The effects of image distortions due to noise, nonuniform negative staining, pitch variations, particle tilt, and flattening on the reconstructed cross-section are difficult to visualize, and therefore we have developed a test system using model images in order to facilitate our investigations. In addition, we have examined the effect of incorrect estimates of the particle repeat length and location of the helical axis on the reconstructed density map. By using models that incorporate defined image distortions, we are able to compare directly reconstructions of the models with those of the idealized structure. This approach can help indicate sources of specimen distortion limiting the resolution of particle reconstructions.
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    Journal of Electron Microscopy Technique 5 (1987), S. 189-198 
    ISSN: 0741-0581
    Keywords: Cyclic deformation ; Fatigue ; High voltage electron microscopy ; In situ fatigue ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: There has been, in the past, only limited success with in situ cyclic or reversed plastic deformation tests in the transmission electron microscope (TEM). This is probably partly due to problems associated with buckling of the foil when an applied tensile or shear stress is reversed. Mechanical analysis shows that dislocation movement can be reversed by tensile stressing in alternating perpendicular directions (i.e., 90° rotations of a tensile stress); thus buckling of the foil can be avoided. A design for performing such X-Y in situ TEM tests is presented, with observations that demonstrate its feasibility.
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    Journal of Electron Microscopy Technique 5 (1987), S. 199-202 
    ISSN: 0741-0581
    Keywords: In situ ; Straining ; TEM ; Polishing ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: A jet-polishing technique has been developed for use in the preparation of microtensile specimens for HVEM examination. The technique requires the use of a pair of Teflon sheet inserts with rectangular openings in a conventional specimen holder. When inserts with optimum opening dimensions are used, specimens having elliptical holes close to the center of the gauge section are produced with large electron-transparent areas at both ends of the long axis. Annealed metal specimens, such as brass or aluminum, prepared by this method are stronger, and can be handled more easily, than those prepared by conventional methods. An advantage of the technique is that reproducible electropolishing conditions and the automatic detection of perforation by a photocell can be used in the normal way.
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    Journal of Electron Microscopy Technique 5 (1987), S. 45-50 
    ISSN: 0741-0581
    Keywords: Cross-sectional TEM specimen ; Modulation doped field effect transistor (MODFET) ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Transmission electron microscopy of cross-sectional samples offers an attractive means to study process evaluation and failure analysis of many semiconducting devices. In the present work, a technique to prepare cross-sectional TEM samples, containing thin sections of specifically desired regions within nonuniform surfaced semiconducting devices, is described.
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    Journal of Electron Microscopy Technique 9 (1988), S. 293-298 
    ISSN: 0741-0581
    Keywords: Renal medulla ; Isolated perfusion ; Anoxic damage ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The tubular epithelial cells located in the renal medulla are normally working in a hypoxic milieu. In isolated rat kidneys perfused with a cell-free medium, the medullary thick ascending limbs of Henle's loop are selectively and reproducibly injured by the imbalance between oxygen demand and supply in this area. Hypoxic lesions rapidly progress from reversible to irreversible forms of cell damage. Reversible injury consists of chromatin margination and mitochondrial swelling, which can disappear upon restoration of an adequate balance of oxygenation. Irreversible injury consists of nuclear pyknosis and cytoplasmic fragmentation, lesions which persist after re-oxygenation or even progress to cell death. Reversible and irreversible phases of hypoxic injury in this distal tubule segment are comparable to, but different from, those previously defined for the proximal tubule.
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    Journal of Electron Microscopy Technique 9 (1988), S. 395-411 
    ISSN: 0741-0581
    Keywords: Serial thick sections ; HVEM ; Stereoscopic viewing ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: A comprehensive computer-graphics-based system (STERECON) is described for tracing and digitizing contours from individual or stereopair electron micrographs. The contours are drawn in parallel planes within the micrographs. Provision is also made for tracing and digitizing in full three-dimensional (3-D) coordinates in any direction along linear structures such as cytoskeletal elements. The stereopair micrographs are viewed in combination with the contours being traced on a graphics terminal monitor. This is done either by projecting original electron micrograph (EM) negatives onto a screen and optically combining these images with contour lines being drawn on the monitor, or by first digitizing the images and displaying them directly on the monitor along with the contour lines. Prior image digitization allows computer enhancement of the structures to be contoured. Correction and alignment routines are included to deal with variable section thickness, section distortion and mass loss, variations in photography in the electron microscope, and terminal screen curvature when combining projected images with contour lines on the monitor. The STERECON system organizes and displays the digitized data from successive sections as a 3-D reconstruction. Reconstructions can be viewed in any orientation as contour stacks with hidden lines removed; as wire-frame models; or as shaded, solid models with variable lighting, transparency, and reflectivity. Volumes and surface areas of the reconstructed objects can be determined. Particular attention was paid to making the system convenient for the biological user. Users are given a choice of three different stereo-viewing methods.
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  • 56
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    Journal of Electron Microscopy Technique 10 (1988) 
    ISSN: 0741-0581
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
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  • 57
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    Journal of Electron Microscopy Technique 10 (1988), S. 27-33 
    ISSN: 0741-0581
    Keywords: Electron microscopy ; Image processing ; Image registration ; Robustness ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The geometric registration of two electron microscopic images generally is performed by maximizing the cross-correlation coefficient between them. We show that a new similarity measure (the number of sign changes) is useful for performing simultaneously geometric and gray-level registration. This method is robust, which means that it provides a good estimation of the parameters even in the presence of outliers that cannot be described by the registration model.
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  • 58
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    Journal of Electron Microscopy Technique 10 (1988), S. 67-76 
    ISSN: 0741-0581
    Keywords: Synapse ; Taxi-bodies ; Horseradish peroxidase ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Thin sections of nervous tissue were viewed at different tilt angles using a transmission electron microscope equipped with a eucentric goniometer stage. In a comparison study of various degrees of tilt, one can observe additional morphological features within synaptic profiles, define subsynaptic structures such as Taxi-bodies, and clearly see the crystalline formation of cytochemical tracers. This study demonstrates the value of tilting thin-sections in the analysis of synapses and other biological material at the ultrastructural level.
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  • 59
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    Journal of Electron Microscopy Technique 10 (1988), S. 53-65 
    ISSN: 0741-0581
    Keywords: Records ; Computer program ; Specimen block labels ; Specimen vial labels ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Conventionally, all specimen vial and block labels are handwritten or typed, a labor-intensive process open to human error, particularly in a lab that processes large numbers of samples. The computer program described in this report was developed to reduce or elimiate this problem. The program is menu-driven, asking specific information from the user, and runs on an IBM PC (or compatible). It is designed to accurately produce specimen collection vial labels, resin block labels, and data sheets for inclusion in a research notebook. A task that in the past may have required much time at the typewriter can now be accomplished without error in a few minutes. Although designed to fit the needs of a pathology laboratory, the program (written in BASIC) can be easily modified to fit other applications.
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  • 60
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    Journal of Electron Microscopy Technique 10 (1988), S. 77-85 
    ISSN: 0741-0581
    Keywords: Fluorocarbons ; Cell culture ; Techniques ; Specimen preparation ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: 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.
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  • 61
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    Journal of Electron Microscopy Technique 10 (1988), S. 123-124 
    ISSN: 0741-0581
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 62
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    Journal of Electron Microscopy Technique 10 (1988), S. 205-210 
    ISSN: 0741-0581
    Keywords: Review ; Chemical synapses ; Mammals ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: This paper provides a brief review of the historical development of our understanding of synaptic structure in the central nervous system. The basic structure of the synapse is reviewed as well as the development of ultrastructural techniques that have allowed the details of synaptic organization to be elucidated.
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  • 63
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    Journal of Electron Microscopy Technique 10 (1988), S. 211-212 
    ISSN: 0741-0581
    Keywords: Transmission Electron Microscope ; Phosphors ; Viewing Screen ; Phosphor Viewing Screen ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: A simple procedure is described for the preparation of a totally inorganic, durable, strongly bonded, and non-shrinking phosphor viewing screen. The procedure requires no special apparatus or skills in order to prepare a fairly uniform high resolution screen in only about 0.5 hours plus drying time. The screens are suitable for use on an automatic exposure system where mechanical shock can destroy a screen.
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  • 64
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    Journal of Electron Microscopy Technique 10 (1988), S. 247-263 
    ISSN: 0741-0581
    Keywords: Ultrastructure ; Corpus striatum ; Pallidum ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The synaptic organization of the globus pallidus is reviewed with respect to present knowledge about neurons, fibers, axon terminals, and their intrinsic synaptic relationships. Information derived from studies employing Nissl stains, Golgi impregnations, lesion degeneration techniques, immunohistochemistry, and anterograde axonal labeling in various species are presented along with ultrastructural data. Studies indicate that the globus pallidus contains a principal efferent neuron with smooth or spiny dendrites and simple or complex terminal dendritic arborizations. This cell type receives convergent inputs from intrinsic and extrinsic sources and uses γ-aminobutyric acid as a transmitter. A smaller and separate population of pallidal projection neurons contains acetylcholine. Two other less frequent neuronal types, of small and medium size, have also been recognized. Three to six types of axonal boutons forming synaptic contacts with pallidal neurons have been recognized in various studies. Among these, three types (types I, II, and III) are the most prevalent. Studies indicate that the most frequent category (type I) originates from neostriatal neurons via radial fiber projections and contains immunoreactive GABA and enkephalins. The synaptic architecture of the globus pallidus is dominated by a mosaic-like arrangement of long dendrites that are ensheathed by longitudinally oriented axons making synapses en passant. Triadic synapses involving dendrites that are pre- and postsynaptic are encountered infrequently. Because both striatopallidal and pallidothalamic connections are inhibitory, pallidal target neurons in the thalamus may be “disinhibited” when the neostriatum is activated.
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  • 65
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    Journal of Electron Microscopy Technique 10 (1988), S. 283-292 
    ISSN: 0741-0581
    Keywords: Thalamus ; Presynaptic dendrite ; GABA ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: This study describes the synaptic organization of the thalamic reticular nucleus (TRN) in the rat, cat, and monkey using electron microscopy combined with immunocytochemistry, degeneration, or horseradish peroxidase (HRP) tracing methods. Three morphological types of terminals are described in the TRN of the rat: a small terminal with densely packed spherical vesicles (D-terminal), which originates from the cortex; a large terminal with loosely packed spherical vesicles (L-terminal), which originates in the dorsal thalamus; and a terminal containing flattened synaptic vesicles (F-terminal) that is probably a TRN recurrent collateral. The cortical input to the TRN has been shown by double-labeling studies to terminate directly upon TRN projection neurons. Similar classes of terminals are found in the TRN of cat and monkey, but there is in addition a large terminal with spherical synaptic vesicles that is invaginated by dendritic spines. Also present in the cat and monkey, but not in the rat, are vesicle-containing dendrites and dendritic appendages.In the rat, degeneration experiments indicate that the terminals of TRN projection neurons in the dorsal thalamus are F-terminals. These terminals contain flattened synaptic vesicles and exhibit GABA immunoreactivity.
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  • 66
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    Journal of Electron Microscopy Technique 7 (1987), S. 91-95 
    ISSN: 0741-0581
    Keywords: Lead poison ; Ultrastructure ; X-ray microanalysis ; Intranuclear inclusion ; Concretion ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Intranuclear inclusions have been found in epithelial cells of renal proximal convoluted tubules (RPCT) in lead poisoned animals. It has been suggested previously that the inclusions contained lead. The present report gives evidence to the contrary. Samples of renal cortex were taken from adult rats fed laboratory chow containing 2% lead acetate for 1 month. Under the electron microscope (EM), intranuclear inclusions were observed in epithelial cells of RPCT. They were round or ovoid, and not delineated by a membrane. They consisted of two parts: Peripheral and central. Lysosomes increased in number, and many myelin figures appeared in the cytoplasm. In the lumen of the tubules, high electron-dense concretions were found. By x-ray microranalysis, neither the central part nor the peripheral part of the intranuclear inclusions produced a lead peak in the spectrum. Lysosomes and the cytoplasmic matrix also showed no lead peak. However, when the electron beam was focused on the concretion in the lumen of the RPCT, the Lα peak of lead (10.551 keV) and Kα peak of calcium (3.691 keV) were evident. From these findings it is suggested that intranuclear inclusions in the cells of RPCT are not lead deposits. Rather, it is the concretions found in the lumen of tubule that contain lead.
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  • 67
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    Journal of Electron Microscopy Technique 7 (1987), S. 127-130 
    ISSN: 0741-0581
    Keywords: Mitochondria ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: In the present report, quantitative electron microscopy is applied to the basic theory of traditional Chinese medicine (TCM). The theory of TCM indicates that pi (spleen in TCM) has important roles in human health. One such function of the pi is nourishing the muscles, and our work examines the ultrastructural basis of the pi actins in this role. The number of mitochondria of skeletal muscle per area was measured and analyzed. The results indicate a significant decrease in the number of mitochondria with normal structure and a significant increase in the number of mitochondria with abnormal structure in piqixuzheng (spleen energy deficiency in TCM) rats. Such changes are thought to reduce the energy supply of the muscles. After treatment with sijunzitang (herbs which invigorate functioning of the pi), the data do not show a significant difference when compared with normal rats. It is considered that the energy metabolism of the cells is one of the functions of pi.
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    Journal of Electron Microscopy Technique 7 (1987), S. 177-183 
    ISSN: 0741-0581
    Keywords: Coherence width ; Field emission guns ; Out-of-phase domain boundaries ; Spot splitting microdiffraction ; Electrical instabilities ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Microdiffraction is capable of revealing the local structure within an area of the specimen consisting of only a few, or a few tens of, unit cells. However, the extent to which the diffraction pattern intensities can show the local structure depends strongly on the coherence of the illumination. If the coherence width of the illumination is smaller than the diameter of the electron probe at the specimen level, the details within the diffraction spots, which indicate deviations of the local structure from the periodicity of the crystal, will be lost. The differences in the amount of spot splitting observed in microdiffraction patterns from out-of-phase domain boundaries, observed with two instruments, are attributed to differences in the effective source sizes.
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  • 69
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    Journal of Electron Microscopy Technique 6 (1987), S. 255-301 
    ISSN: 0741-0581
    Keywords: Fixation ; Processing ; Electron microscopy ; Human biopsies ; Diagnosis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Transmission electron microscopy serves a useful and often diagnostic purpose in the analysis of human disease. The emerging discipline of ultrastructural pathology serves a much wider field than that of kidney pathology and, of necessity, requires two essential elements. These are (1) the interpretive knowledge which covers all cells in all tissues which compose all organs, their normal substructural composition, and the ultrastructural expression of all of the basic mechanisms of the pathobiology of human disease, and (2) technically excellent preparations of these varied specimens.In this review, we emphasize the technical aspects necessary for the preparation of these specimens. These include the handling of varied specimens from the time of interruption of blood flow to the sample until fixation, fixation methodology, and routine processing methods for electron microscopy. Specialized techniques that are readily accomplished in an ultrastructural pathology service laboratory are also described. These include methods for the demonstration of glycogen, peroxidase(s), the glycocalyx. We also describe the preparation of permanent, alkaline Giemsa-stained 1-μm plastic sections for light microscopic diagnosis, the use of an agar-pelleting technique to change cell suspensions into readily handled blocks, and the use of Spurr's (J. Ultrastruct. Res. 26:31, 1969) low viscosity embedding for all skin and heavily collagenized specimens.The diagnostic report for individual samples can routinely be available within 24 hours of specimen arrival in the ultrastructural pathology laboratory with the methods we review here. Examples of these varied samples of human tissues and cells and methods for preparing them are illustrated. We have found such methods useful for diagnostic purposes, e.g., to identify the site of origin of a brain metastasis as the alveolar cell (type II pneumocyte) of the lung, based on the presence of typical lamellar (surfactant) bodies in the metastatic tumor cells (Dvorak and Monahan-Earley: Norelco Reporter 32:29-36, 1985c), as well as to describe for the first time a new tumor, such as the gut autonomic nerve (GAN) tumor (Walker and Dvorak: Arch. Pathol. Lab. Med. 110:309-316, 1986) or a cell injury process, axonal necrosis, to be characteristic of Crohn's disease (Dvorak et al.: Hum. Pathol. 11:620-634, 1980d; Dvorak and Silen: Ann. Surg. 201:53-63, 1985).
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    Journal of Electron Microscopy Technique 6 (1987), S. 325-333 
    ISSN: 0741-0581
    Keywords: Cryo-SEM ; Cold stage ; Frozen hydrated specimens ; Specimen preparation ; Penicillium cultures ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Penicillium nalgiovense cultures, which are used in the food industry, were found to be collapsed when prepared by standard procedures for scanning electron microscopy. Neither freeze-drying nor critical point-drying preserved the structure of cultures grown on agar media. Cryofixation and preparation of frozen hydrated samples using the Hexland Cryotrans CT 1000 attachment in conjunction with an AMR 1000A scanning electron microscope yielded micrographs of uncollapsed structures which could be used for morphological characterization. Several additional steps had to be used in sample preparation to achieve satisfactory results. Samples were held in a humid chamber prior to freezing; growth substrate was trimmed as thinly as possible (less than 1 mm above the support); the sides of samples were painted with a conductive cement to their upper edge; and frozen samples were coated intermittently with gold sputtered in several 2-min bursts.
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  • 71
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    Journal of Electron Microscopy Technique 7 (1987) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 72
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    Journal of Electron Microscopy Technique 7 (1987), S. 17-27 
    ISSN: 0741-0581
    Keywords: Exoplasmic cell surface ; Protoplasmic cell surface ; Ultrastructure ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Using rotary replication with platinum and carbon to embedment-free sections of polyethylene glycol (PEG)-embedded tissue from which PEG had been removed, the membrane specializations on the outer (exoplasmic) and inner (protoplasmic) cell surface as well as the organization of the cytoskeleton was demonstrated. The high quality and excellent preservation were comparable to that obtained by the rapid-freezing, deep-etched replica method. The present results indicate that the PEG method is essentially acceptable as a reliable morphological technique. Because either sectioned or replica images from the same tissue cells can be observed simultaneously, the PEG method with rotary replication should provide valuable information on cell ultrastructure.
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    Journal of Electron Microscopy Technique 7 (1987) 
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    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
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  • 74
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    Journal of Electron Microscopy Technique 7 (1987), S. 63-63 
    ISSN: 0741-0581
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
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  • 75
    ISSN: 0741-0581
    Keywords: Virus ; Electron microscopic autoradiography ; Pathology ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: To determine the pathogenesis of herpes cervicitis and the relationship between herpes simplex virus type 2 (HSV-2) and the carcinogenesis of human uterine cervix, the ultrastructural changes of 15 cases of long-term organ cultures of human uterine cervix infected with HSV-2 were studied. In order to demonstrate the morphogenesis of the virus and the interactions between virus and host cells, EM autoradiography was performed. After viral inoculation, the course of viral DNA replication, and the processes of maturation of virus were examined. Pathological alterations of infected nuclei-including two kinds of granular matrix aggregations, proliferative changes in nuclei and nuclear envelope, multi-lobular nucleated giant cell formation, intranuclear microtubules, and some evidence of replication of HSV-2 in cytoplasm-were observed. Because of the similarity of the pathologic alterations and the course and duration of infection in the clinic cases and our experimental subjects, this system appears to be a good model to investigate the pathogenesis of herpes cervicitis and the relationship between human cervical cancer and HSV-2, other viruses, or other co-carcinogens.
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    Journal of Electron Microscopy Technique 7 (1987), S. 111-117 
    ISSN: 0741-0581
    Keywords: Hemorrhagic fever virus ; Golgi apparatus ; Viral inclusion bodies ; Neurons ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The morphology and morphogenesis of the virus of hemorrhagic fever with renal syndrome (HFRS) and the associated ultrastructural changes in neurons of the infected mouse brain were examined by electron microscopy. The primary location of the infection in large neurons was in the Golgi apparatus, which had highly proliferated laminar and vesicular profiles. A small number of matured virus particles were found later individually or in small groups within the distended Golgi cisternae and vesicles. Most of the virus particles were round, oval, or elongated and measured about 70-110 nm in diameter. A lipid bilayered viral envelope with an external fringe of surface projections could be resolved at high magnification. The maturation (budding) of the virus occurred exclusively at smooth membrane vesicles, and predominantly at membranes in, or adjacent to, Golgi cisternae. Viral inclusion bodies containing fine filamentous material were seen frequently in close proximity to sites of virus maturation. The known morphological and morphogenetic characteristics of the virus particles observed in infected mouse brain gave further evidence for taxonomic identification of HFRS virus as a member of the family of Bunyaviridae.
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  • 77
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    Journal of Electron Microscopy Technique 7 (1987), S. 161-166 
    ISSN: 0741-0581
    Keywords: Selective plasma etch ; Ceramic composites ; Transmission electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Transmission electron microscopy has been used to isolate and examine the intergranular glass phase in hot-pressed silicon nitride/silicon carbide composites. Previously there have been difficulties in locating a suitable region for studies of this nature because the interfering nitride and carbide grains inhibit isolation of the glass for examination. Radiofrequency plasma etching of thinned sections of 6 wt% Y2O3, 2 wt% A12O3 in Si3N4 containing 30 vol% of SiC proved to be fruitful in isolating the glass phase. A mixture of CF4 and O2 quantitatively remove the acicular nitride phase without any evidence of attack on either the glass or carbide. Composites containing ceria and magnesia as substitutes for yttria behave similarly. This indicates that glasses containing minor to major concentrations of elements forming stable fluorides inhibit the attack of fluoride ions on silica glasses containing these elements.
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    Journal of Electron Microscopy Technique 7 (1987), S. 185-189 
    ISSN: 0741-0581
    Keywords: Preparation of cryosections ; Software-controlled advance system ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Cryoultramicrotomy is gaining in significance and use as technical improvements are made. In comparison with epoxy resin procedures, cryopreparations are more rapid; there is only a negligible loss of material and thus antigenicity is well preserved.The present work contains some newly developed details for the exact determination of the advancement of the sample in the direction of the knife in a microtome. It is a software-controlled ultramicrotome advance drive system with feedback regulation as well as repeatedly patented devices for advancement sensors.
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  • 79
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    Journal of Electron Microscopy Technique 7 (1987), S. 233-234 
    ISSN: 0741-0581
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
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  • 80
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    Journal of Electron Microscopy Technique 7 (1987), S. 205-221 
    ISSN: 0741-0581
    Keywords: Lamellar structures ; Myelin figures ; Lipoprotein lipase ; Triacylglycerol ; Adipose tissue ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Long-chain fatty acids are important structural and metabolic functions in tissues. Fatty acids are derived from triacylglycerol-rich particles in capillaries (chylomicrons and very-low-density lipoproteins) and from triacylglycerol stored in cells (lipid droplets) by the hydrolytic activity of tissue lipases.The identification and localization of fatty acids in tissues has been considered difficult to obtain by using conventional ultrastructural techniques. However, structural findings from our studies on fatty acid transport in tissue became interpretable due to the use of many overlapping techniques. We present here these ultrastructural techniques developed to study fatty acids in tissues and review data which demonstrate lipase activity and fatty acid production from triacylglycerol in aldehyde-fixed tissue. Accumulations of fatty acid in tissue are present as lamellar structures with periodicity of 40-50 Å in sections of resin-embedded tissue and as hydrated myelin figures in freeze fracture replicas of unfixed and fixed tissue. Finally, a new method, using the ionization properties of fatty acids combined with freeze fracture, locates these amphipathic molecules to leaflets of membrane bilayers.
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  • 81
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    Journal of Electron Microscopy Technique 7 (1987), S. 237-254 
    ISSN: 0741-0581
    Keywords: HREM ; Image contrast ; Image deconvolution ; Resolution enhancement ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: A review of research on high-resolution electron microscopy (HREM) carried out at the Institute of Physics, the Chinese Academy of Sciences, is presented. Apart from the direct observation of crystal and quasicrystal defects for some alloys, oxides, minerals, etc., and the structure determination for some minute crystals, an approximate image-contrast theory named pseudo-weak-phase object approximation (PWPOA), which shows the image contrast change with crystal thickness, is described. Within the framework of PWPOA, the image contrast of lithium ions in the crystal of R-Li2Ti3O7 has been observed. The usefulness of diffraction analysis techniques such as the direct method and Patterson method in HREM is discussed. Image deconvolution and resolution enhancement for weak-phase objects by use of the direct method are illustrated. In addition, preliminary results of image restoration for thick crystals are given.
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  • 82
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    Journal of Electron Microscopy Technique 7 (1987), S. 277-282 
    ISSN: 0741-0581
    Keywords: Electron microscopy ; Electron diffraction ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: New findings on quasicrystals with icosahedral, octagonal, decagonal, and dodecagonal symmetries obtained recently in the Beijing Laboratory of Electron Microscopy, Chinese Academy of Sciences, are presented. Special emphasis is put on the relation between quasicrystalline and crystalline structures. The important role played by electron diffraction and high-resolution electron microscopy in revealing these quasiperiodic structures is pointed out.
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  • 83
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    Journal of Electron Microscopy Technique 7 (1987), S. 313-317 
    ISSN: 0741-0581
    Keywords: Microanalysis ; EDS ; HREM ; Coherence ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The intensity distribution in the microdiffraction pattern depends strongly on the coherence of the illuminated source. The coherence width at the specimen level is considered as a parameter to check the coherence of an electron microscope. Two application examples are illustrated. A small interphase precipitate of MgNi2 in an Ni superalloy has been identified by a combination of microdiffraction and energy dispersive spectrum (EDS) techniques, though it can not be found by conventional transmission electron microscopy (TEM) and selected area diffraction (SAD). By means of microdiffraction as well as high-resolution electron microscopy (HREM) imaging a defect structure has been determined. Such a defect makes the lattice extinction spots appear with various intensities in the selected area diffraction and microdiffraction patterns.
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  • 84
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    Journal of Electron Microscopy Technique 7 (1987), S. 323-329 
    ISSN: 0741-0581
    Keywords: Standardless analysis ; X-ray EDS ; Electron beam ; Microanalysis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: A direct relationship between the x-ray intensity ratio and the concentration ratio for bulk and thin specimens has been established by use of a revised full-diffusion model of electron scattering. The suitable ionization cross section, the most important parameter influencing the accuracy of the calculated Cliff-Lorimer factors, has been found after comparing the experimental intensity ratio I(L)/I(K) of eight elements (from Ge to Sn) and I(M)/I(L) of six elements (from Sm to Bi) with the calculated values. The quantitative standardless EDS analysis of bulk samples obtained by this direct method is more satisfactory than the commercial indirect method which gives the composition through ZAF correction after calculating the intensity factors of pure elements. The quantitative standardless analysis of thin samples has been improved by the suitable cross section significantly. This method has been applied to the analysis of film on substrate either without any common element or with one common element (P-Si glass film on Si). It has also been used to calculate the intensity factors of pure bulk samples and the backscattering correction factor in Auger electron spectroscopy.
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  • 85
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    Journal of Electron Microscopy Technique 8 (1988), S. 17-40 
    ISSN: 0741-0581
    Keywords: Electron microscopy ; Heteroduplex mapping ; Lentiviruses ; Retroviruses ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: A novel human lymphotropic virus capable of crippling the immune system by infecting and destroying T4 antigen-positive cells is now known to be the etiologic agent of the acquired immune deficiency syndrome (AIDS). The AIDS or human immunodeficiency virus (HIV) belongs to a family of RNA viruses called retroviruses. Several strains of HIV have been molecularly cloned, and DNA sequence comparisons have established that the proviral DNA genome is 9.7 kilobase pairs. The genome possesses characteristic retrovirus features including structural genes, flanked by long terminal repeats, in the order gag, pol, and env and, in addition, four unique nonstructural genes, several of which appear to be essential in regulating virus replication. Electron microscopy has played an important role in elucidating structural, genetic, and molecular properties of HIV and has aided in its classification as a member of the Lentivirnae retrovirus subfamily. Heteroduplex mapping methodologies pertinent to these findings are described. Although the relationships show considerable divergence, the similarities between HIV and lentiviruses are profound and encompass an indistinguishable morphology, genome sequence homology and topography, genomic diversity, and overlapping biology, including a preference for infecting cells of the immune system, a cytopathic effect in vitro, and the ability to produce a persistent, slowly progressing, degenerative disease in vivo. The newest HIV class (HIV-2) has recently been molecularly characterized. HIV-2 also bears all the hallmarks of a lentivirus but is more closely related to simian immunodeficiency viruses than the previously described HIV-1, despite a similar biology. The HIV-lentivirus phylogenetic relationship has broad implications for the AIDS disease process and has given new importance to the study of the natural history and pathogenesis of animal lentiviruses in searching for clues to prevent the spread of AIDS.
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  • 86
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    Journal of Electron Microscopy Technique 8 (1988), S. 133-135 
    ISSN: 0741-0581
    Keywords: Strongyloides stercoralis ; Strongyloidiasis ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Strongyloides stercoralis, the only helminthic parasite that can complete its life cycle in the human host, is also the only helminthic parasite that has been reported with any frequency in AIDS patients. Symptoms include hives, skin eruptions, abdominal pain, perianal pruitis, diarrhea, and pneumonitis. Diagnosis is made by demonstrating rhabditiform larvae in the stool or female parasitic worms and eggs in the small intestinal mucosa; in disseminated cases, rhabditiform or filariform larvae can be found in liver, heart, lungs, thyroid, kidneys, adrenals, pancreas, lymph nodes, and central nervous system. Successful treatment has been achieved with thiabendazol. Strongyloidiasis is uncommon, but since cell-mediated immunity is important in combatting this organism, and since T-lymphocyte function is impaired in AIDS patients, strongyloidiasis should not be overlooked in the diagnosis of opportunistic illnesses in these individuals.
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  • 87
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    Journal of Electron Microscopy Technique 8 (1988), S. 159-172 
    ISSN: 0741-0581
    Keywords: Gray scale enhancement ; Immotile cilia syndrome ; Electron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Tracheal ciliary cross sections were examined with scanning transmission electron microscopy and the resultant images were digitized for image enhancement. A gray-scale histogram of each ciliary image was produced and manipulated to enhance the image for dynein arms. Tracheal epithelial tissue from the pig, rabbit, and dog, including dogs with immotile cilia syndrome, was examined by using this technique. Tissue from each animal was fixed with each of three different fixatives and sections were evaluated for preservation of dynein arms. The same fixative did not consistently provide optimal fixation for ciliary dynein arms in all three species examined. Each species, therefore, must be evaluated to determine the optimal fixative for preservation of normal ciliary ultrastructure. Digital image processing provides a mechanism for enhancing dynein arms in situ without the need for addition of special stains or the use of techniques such as image summation. With this technique it has been shown that about two-thirds of outer dynein arms are partially or completely missing on cilia from dogs with immotile cilia syndrome.
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  • 88
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    Journal of Electron Microscopy Technique 8 (1988), S. 225-226 
    ISSN: 0741-0581
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
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  • 89
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    Journal of Electron Microscopy Technique 8 (1988), S. 229-230 
    ISSN: 0741-0581
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: In problems of air or water pollution, or in evaluation of exposure to pathogenic dusts from biological specimens ( e.g., asbestos fibers) some typical particles can be used as tracers. As far as they have sufficiently typical properties (shape, color, anisotropy,…) particles are rapidly recognized and quantified by light microscopy (LM), even if they are very scarce or dispersed among large amounts of unsignificant ones. For accurate characterization, analytical electron microscopy (scanning or transmission) is required, but cannot be efficiently applied for low concentrations of particles. A technique using a high precision object-marker under LM has been developed in the past by Jedwab (1975) to be used with SEM, but there is actually no equivalent for TEM. Such a technique is proposed in this paper. Its major interest resides in the greater amount of analytical data available for one single particle (high magnification morphology, crystallographic structure, chemistry). Practical results were obtained with asbestos fibers and bodies recovered from biological specimens, but the technique can be extended to many other problems concerning micron-sized particles.
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  • 90
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    Journal of Electron Microscopy Technique 8 (1988), S. 233-235 
    ISSN: 0741-0581
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
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  • 91
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    Journal of Electron Microscopy Technique 8 (1988), S. 239-240 
    ISSN: 0741-0581
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
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  • 92
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    Journal of Electron Microscopy Technique 8 (1988), S. 263-272 
    ISSN: 0741-0581
    Keywords: High Tc superconductors ; Electron microscopy ; HREM image stimulations ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Thin films of the superconductive oxide YBa2Cu3O7-x have been made by electron-beam coevaporation of the metals in an oxygen atmosphere onto single-crystal {001}-oriented SrTiO3 and yttria-stabilized zirconia (YSZ) substrates. The oxide films were superconducting in the as-deposited state (Tc = 81-83K, Jc = 106 A/cm2 at 4.2K). Bright-field imaging, selectedarea diffraction (SAD), and high-resolution imaging in the transmission electron microscope were used to characterize the microstructure of these films. All of the films were polycrystalline. On SrTiO3 the films were oriented, for the most part, with {110} parallel to the substrate surface. On YSZ, two microstructures were observed: one with smaller rectangular grains oriented with (100) or (010) parallel to the substrate surface and the other with (001) parallel to the surface (i.e., c-axis up).
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  • 93
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    Journal of Electron Microscopy Technique 8 (1988), S. 311-315 
    ISSN: 0741-0581
    Keywords: Hi-Tc superconductivity ; STEM ; Electronic structure ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: We have obtained the electron-energy-loss spectra below 1,000 eV for YBa2Cu3O7-δ. The spectra show contributions from all elemental constituents, although the Y-signal is very weak owing to its small concentration. The low-loss region and the Ba-core losses are very similar to those obtained for BaO. The Cu absorption is similar to that seen in CuO with minor differences relating to Cu concentration and anisotropy. The oxygen 1s absorption has a shape that is quite different from that obtained in CuO and shows striking orientational anisotropy. Radiation damage in the microscope is a problem and leads to changes in the shape of the oxygen edge.
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  • 94
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    Journal of Electron Microscopy Technique 8 (1988), S. 307-309 
    ISSN: 0741-0581
    Keywords: Electron energy loss spectroscopy ; Varying O2 content ; Crystallographic orientation dependence of oxygen near edge features ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The high Tc superconducting material YBa2Cu3O7 shows a complex relationship between microstructure and oxygen content, which are controlled by length of heat treatment, atmosphere, and quench rate. An AEM investigation studying changes in the oxygen near edge features was undertaken. Electron energy loss spectroscopy (EELS) measurements have the important advantage that they can be made on single crystal grains, allowing orentation-dependent studies. Both ion-milled and crushed samples with varying O2 content were analyzed. The structure of YBaCu3O7 was determined by neutron diffraction to be orthorhombic with distinct Cu-O chains along the b-axis as well as Cu-O planes in the a - b plane. Therefore, by looking for a crystallographic dependence of the oxygen K-edge one might be able to distinguish inequivalent oxygen atoms by their core level binding energy and correlate site occupancy with varying O2 content. The EELS results on the oxygen K-edge are strongly dependent on oxygen content, most noticeably when the c-axis is parallel to the electron beam.
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  • 95
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    Journal of Electron Microscopy Technique 8 (1988), S. 325-337 
    ISSN: 0741-0581
    Keywords: YBa2Cu3O7 ; High Tc superconductor ; Martensitic transformation ; HRTEM ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Direct structure images of the YBa2Cu3O7-x high Tc superconducting ceramic (also called the 1-2-3 compound) at 1.7 Å resolution have been obtained for the [100] and [001] orientations. It was found that for the purposes of studying oxygen ordering in this compound it is better to use lattice images of lower resolution. The oxygen ordering was studied via the measurement of the bending of (100) and (110) lattice planes on crossing the (110) twin boundaries in crystals oriented in the [001] zone. Significant variations were found in the b/a ratios, owning to a variation in oxygen ordering, between different crystal grains, and between different regions in the same grain. For the three different 1-2-2 samples studied, the average b/a ration was 1.016, the same value as was found in neutron diffraction studies. The twin boundaries in the orthorhombic 1-2-3 phase are sharp and planar. It seems likely that the transformation from the high-temperature tetragonal phase to the lower-temperature orthorhombic phase is martensitic in nature. A new phase has been discovered on some of the twin boundaries. The new phase can be indexed as tetragonal with a = 7.5 ± 0.2 Å, and c = 6.8 ± 0.2 Å. It is possible that the new phase is stabilized by the stress which occurs at the twin boundaries.
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  • 96
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    Journal of Electron Microscopy Technique 8 (1988), S. 363-370 
    ISSN: 0741-0581
    Keywords: Three-dimensional organization ; Membrane glycoconjugates ; Gold labeling ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Recently, cytochemical techniques have been applied for localizing membrane components; however, transmission electron microscopy only provides two-dimensional information about their distribution. Scanning electron microscopy, on the other hand, offers the possibility of examining the three-dimensional architecture of biological samples. The fracture-label cytochemical technique was combined with the backscattered electron imaging (BEI) mode of the scanning electron microscope to visualize the in vivo distribution of lectin binding sites on freeze-fractured biological membranes in tissues and cells. Pancreatic and testicular tissues, fixed with glutaraldehyde, were freeze-fractured and labeled with Helix pomatialectin-gold or Ricinus communis I-gold complexes. The labeled specimens were then critical-point dried and replicated with platinum-carbon for routine transmission electron microscopy or with carbon alone for BEL. Lectin-gold labeling of fractured plasma and intracellular membranes observed with BEI showed a labeling pattern similar to that seen by the replica method. However, BEI-fracturelabel provided additional information about the distribution of the labeling with respect to three-dimensional organization of tissues and cells. Large sample areas could be examined, making this technique particularly useful as a survey method for specimens that are either differentially labeled or composed of heterogenous cell populations.
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  • 97
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    Journal of Electron Microscopy Technique 8 (1988), S. 401-432 
    ISSN: 0741-0581
    Keywords: Electron microscopy ; Immunoelectron microscopy ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The present review deals with the use of electron microscopy in the identification of pituitary cell types as well as the assessment of their functional state, in rat and man. Application of immunoelectron microscopy, especially immunogold techniques, utilizing multiple labeling in establishing differentiation and hormone content of cell types, is emphasized. Recent evidence of plurihormonality in various pituitary cell types indicates that the once axiomatic one cell-one hormone theory is untenable and that the present perception of pituitary cell types and their function requires modification. Detection of hormonal and nonhormonal substances in pituitary cell types, not associated with their known endocrine function, suggests that hypophysial cells may have yet unknown roles, possibly in the realm of paracrine and autocrine regulation.
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  • 98
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    Journal of Electron Microscopy Technique 8 (1988), S. 443-444 
    ISSN: 0741-0581
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
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  • 99
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    Journal of Electron Microscopy Technique 9 (1988), S. 19-43 
    ISSN: 0741-0581
    Keywords: Continuum ; Thin sections ; Microdroplets ; Water content ; Bulk specimens ; Semithick specimens ; Mass loss ; Standards ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Qualitative X-ray microanalysis of biological specimens requires an approach that is somewhat different from that used in the materials sciences. The first step is deconvolution and background subtraction on the obtained spectrum. The further treatment depends on the type of specimen: thin, thick, or semithick. For thin sections, the continuum method of quantitation is most often used, but it should be combined with an accurate correction for extraneous background. However, alternative methods to determine local mass should also be considered. In the analysis of biological bulk specimens, the ZAF-correction method appears to be less useful, primarily because of the uneven surface of biological specimens. The peak-to-local background model may be a more adequate method for thick specimens that are not mounted on a thick substrate. Quantitative X-ray microanalysis of biological specimens generally requires the use of standards that preferably should resemble the specimen in chemical and physical properties. Special problems in biological microanalysis include low count rates, specimen instability and mass loss, extraneous contributions to the spectrum, and preparative artifacts affecting quantitation. A relatively recent development in X-ray microanalysis of biological specimens is the quantitative determination of local water content.
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  • 100
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    Journal of Electron Microscopy Technique 9 (1988), S. 83-98 
    ISSN: 0741-0581
    Keywords: X-ray microanalysis ; Pathology ; Diagnosis ; Cryo(ultra)-microtomy ; Cultured cells ; Freeze-drying ; Freeze-substitution ; Low-temperature embedding ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Many diseases are associated with a change in the distribution of diffusible ions at the cell or tissue level. These diseases can profitably be studied by X-ray microanalysis. This technique for the study of ion distribution requires the use of cryoprepared specimens. Analysis at low or medium resolution can be carried out on thick or semi-thick cryosections, or on frozenhydrated or freeze-dried embedded bulk samples. Such analyses are particularly useful in the initial stages of an investigation or when data from a large number of samples have to be acquired. Also X-ray microanalysis of cultured or single cells prepared by freeze-drying can be used to rapidly collect information on a large number of cells. Analysis at high resolution has to be carried out on thin sections: Cryosections or sections of freeze-substituted or freeze-dried embedded tissue. For the latter type of specimens, the use of low-temperature embedding methods may have important advantages.
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