bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cryo preparation of isolated rabbit pancreatic islets
Authors: Sato Tamiko , Herman Lawrence 
Published: February 2005

AbstractA Flotronic silver membrane has been used as a vehicle to process, via freeze substitution, collagenase‐derived rabbit pancreatic islets. The procedure provides: (1) a simple, inexpensive method for handling larger numbers of tightly clustered islet aggregates; (2) a metal surface for rapid heat transfer from specimen to cryogen resulting in an increased circumferential zone of fine structural preservation; (3) the elimination of possible artifacts associated with impact or rotation of biological specimens against a cooled, highly polished metal block; (4) superior preservation of structural components not usually observed by conventional modes of fixation; (5) retention of metabolic components which may subsequently be available for immunocytochemical or X‐ray energy dispersive procedures.
Cathodoluminescence attachment to an electron probe instrument
Authors: Yacobi B. G. , Herrington C. R. 
Published: February 2005

AbstractA simple cathodoluminescence (CL) attachment to a JEOL JSM‐840 scanning electron microscope (SEM) is described. It is based on a Si photodiode mounted inside the SEM chamber. The current amplifier of a backscattered electron detector unit, which is a standard feature of this SEM, is used to amplify and display the CL images. Examples of CL panchromatic (integral) images of GaAs, InP, and ZnS crystals are presented.
Detection of sulfur in fixed and embedded rat peritoneal mast cell granules by X‐ray energy dispersive spectroscopy
Authors: Caulfield John P. , Hein Ann , Tsunoda Kin‐Ichi , Shapiro Robert 
Published: February 2005

AbstractPurified rat peritoneal mast cells contained 3.3 × 10−5 gm SO4 and 2.2 × 10−8 gm Ca/106 cells. The molar ratio of S/Ca in the whole cell was 600:1. Frozen thin sections of unfixed mast cells contained only sulfur (S) in the granules when examined by X‐ray energy dispersive spectroscopy (EDS). Mast cells fixed in 3% glutaraldehyde and 1.5% formaldehyde in 75% ethanol (Et/Ald) or in mixed buffered aldehydes and embedded in Epon 812 or the low viscosity resin diepoxyoctane (DEO) contained S in all granules and Ca in some of the granules measured. Neither element was found in the nucleus, cytoplasm, or resin. Isolated, Et/Ald fixed and embedded granules also contained S. The presence of Ca in the granules was artifactual in that the Ca was absorbed from water in the trough of the diamond knife and/or from the filter paper used to blot the sections dry. This phenomenon was investigated further. Sections of Et/Ald fixed and embedded mast cells were incubated with 5 × 10−6 to 10−2 M CaCl2. Ca was detectable in 100% of the granules incubated at concentrations ≥ 10−4 M and reached a constant S/Ca ratio of 2.0 at concentrations ≥ 10−3 M. Ca was not detectable in the nucleus, cytoplasm, or resin at 10−2 M. A plot of S versus Ca counts from the granules of cells incubated with 10−2 M CaCl2 was linear with a slope of 2.0 and a correlation coefficient of 0.88. Et/Ald fixed cells incubated with distilled H2O had fewer granules containing Ca, 10%, than unincubated cells, 77%. Further, H2O removed all Ca from Et/Ald fixed cells embedded in DEO. These studies show that S, which is present as SO4 on the proteoglycan heparin, is readily detectable by X‐ray EDS in fixed and embedded cells. An artifact of the technique is that weak anionic sites, which are most probably carboxyl groups on the proteoglycan, can bind the divalent cation Ca and cause spurious localization.
A comparison of on‐line digital recording with conventional photographic recording for scanning electron microscopy
Authors: Oho Eisaku , Sasaki Toshihide , Kanaya Koichi 
Published: February 2005

AbstractThe scanning electron microscope (SEM) has previously utilized a video monitor plus camera as the image recording system. However, this conventional method is inefficient in relation to information present in the original electric signal. Therefore, we propose, for general use, an on‐line recording system consisting of an A‐D converter, image memory, and computer. In addition, we found that the effect of vibration in the SEM image could be reduced by application of the digital recording system. In the present study, interpolation and signal averaging programs were utilized for confirming the performance level of the on‐line recording system. These programs were found to be very effective for SEM.
Quantitative analysis of synapse structure with a semiautomatic interactive computer system: A study on identified pyramidal tract neurons in the sensory‐motor cortex of cat
Authors: Saito Kiichiro , Niki Kazuhisa , Eins Siegfried , Wolff Joachim R. 
Published: February 2005

AbstractPyramidal tract (Pt) neurons in the sensory‐motor cortex of cat were labeled by injection of HRP into the spinal cord. Ultrastructural and quantitative analysis of the synaptic covering of their soma and apical dendrite (up to 100 μm from soma) was undertaken. We intercalated a visual‐manual treatment between composite electron micrographs and a fully automated computer system and developed specific programs for evaluation of the morphometric data. Programs are included. A total of 412 synaptic boutons were examined that were found in contact with large Pt neurons. The mean linear percentage of the surface area covered by boutons was 26.2 ± 8.4% and the mean contacting length and cross‐sectional area of the bouton profiles were 1.28 ± 0.58 μm and 0.89 ± 0.59 μm2, respectively. All types of boutons with active zones accounted for 41.2% of the total. The distribution of two types of bouton (S‐ and F‐type boutons, showing asymmetric and symmetric contacts, respectively) was examined quantitatively. The mean proportion of F‐type boutons was 89.1% with a soma and S‐type boutons contacting apical dendrites was 10.9%. In addition, GABAergic boutons were identified with the soma by immunocytochemistry with antibodies against glutamic acid decarboxylase. They formed symmetric synaptic contacts with the Pt cells that were identical to those formed by F‐type boutons. The quantitative analysis revealed that synaptic clefts are narrower and synaptic vesicles are smaller in symmetric F‐type boutons than in S‐type boutons forming asymmetric contacts. These data establish that at least three parameters (postsynaptic density, synaptic cleft, and size of vesicles) can be utilized singly or in combination to identify GABAergic inhibitory synapses in neocortex.
A new heavy‐metal‐containing resin for low‐temperature embedding and imaging of unstained sections of biological material
Authors: Acetarin Jean‐Dominique , Villiger Werner , Carlemalm Eric 
Published: February 2005

AbstractA styrene‐based, low viscosity, negative‐staining resin has been formulated for low‐temperature embedding of unstained biological material. The resin, containing 3 atom% tin, permits sample preparations at 243°K, and provides sufficient contrast with bright field conventional transmission electron microscopy (CTEM) and excellent contrast in scanning transmission electron microscopy (STEM) ratio mode.
Influence of tissue composition on the final volume of rat liver blocks prepared for electron microscopy
Authors: Bertram John F. , Bolender Robert P. , Sampson Paul D. 
Published: February 2005

AbstractMethods for measuring and evaluating changes in volume of small tissue blocks prepared for transmission electron microscopy are presented. The results indicate: (1) that some blocks swell and others shrink, and (2) that changes in block volume can be explained by inhomogeneous changes occurring in three different tissue compartments.For stereological studies attempting to extrapolate changes in fixed and embedded tissue to those of fresh tissue, consequences of inhomogeneous volume changes in tissue compartments include a decrease in reliability and an increase in statistical variance of stereological density estimates. Since factors could not be found to correct for the changes in individual tissue compartments, alternative strategies are considered for dealing with the volume artifacts of fixation.
Ultrastructural patterns of ferritin permeation into glutaraldehyde‐fixed freeze‐fractured sarcomeres characterize stages of contraction in striated muscle
Authors: Barbosa Maria Luiza F. , Silva Pedro Pinto Da 
Published: February 2005

AbstractWe show that “fracture—permeation”—a method developed to assess the compactness of the cytoplasm—can establish the distribution of intermolecular spaces in the sarcomeres of glutaraldehyde‐fixed striated muscle. As examples of striated muscle, we use sartorius muscle from toad (Bufo marinus) and papillary cardiac muscle from the left ventricle of Sprague—Dawley rats. Tissues were fixed in glutaraldehyde, frozen, cross‐fractured in liquid nitrogen, and thawed. Tissue fragments were immersed in concentrated solutions of native ferritin (30% w/v). Random fractures gave ferritin direct access to all regions of the sarcomere. We show that a sequence of four qualitatively distinct patterns of ferritin distribution is associated to a progressive sequence of sarcomere lengths. The correspondence between sarcomere lengths and patterns of ferritin permeation permits the recognition of sarcomeres in rigor (no penetration of ferritin), stretched (penetration into the I band and H zone), or at rest length (penetration restricted to the I band). Similar patterns of ferritin permeation can also be recognized in oblique sections. In cardiac muscle, ferritin permeates into the A bands of contracted sarcomeres and shows an increase in disorder within the filament lattice during contraction. The patterns of ferritin permeation observed in sarcomeres in rigor, stretched, or at rest length are those predicted from changes in filament overlapping proposed by Huxley's “sliding filament theory of muscle contraction.” Our results illustrate the power of fracture‐permeation to investigate intermolecular distances in cytoplasmic matrices.
Specimen handling and data interpretation in x‐ray microanalysis of frozen hydrated etched gastrointestinal tract
Authors: Carr K. E. , Hayes T. L. , Watt A. , Bastacky S. J. , Klein S. , Fife M. 
Published: February 2005

AbstractLow temperature scanning electron microscopy of mammalian tissue allows microanalysis data and morphological results to be considered together, without the risk of elemental diffusion introduced by liquid fixatives and processing agents. The technique, however, is time consuming and there are many areas where errors are possible and standardization of technique is advisable. The present paper describes some of the problems inherent in handling frozen tissue and comparison is made between microanalytical measurements from luminal contents and those from villous epithelium.
Preparation of lithium specimens for transmission electron microscopy
Authors: Liu Dang‐Rong , Rommal H. E. George , Williams David B. 
Published: February 2005

AbstractA method of preparing undeformed thin lithium specimens for TEM is described. A solution of dehydrated methanol and toluene is used both for initial dishing of the foil by chemical polishing and also for final thinning. Under electron beam irradiation in the TEM, new pure Li crystals can grow out of the existing Li specimen. These in situ crystals can be used for the study of the microstructure and electronic structure of Li using TEM and electron energy loss spectrometry.
Combined quick freezing, freeze‐drying, and embedding tissue at low temperature and in low viscosity resins
Authors: Chiovetti Robert , McGuffee Linda J. , Little Sally A. , Wheeler‐Clark Ellyn , Brass‐Dale Jutta 
Published: February 2005

AbstractThe 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.
Imaging of thermal and elastic surface properties by scanning electron acoustic microscopy
Authors: Holstein W. L. 
Published: February 2005

AbstractScanning 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.
Sectionable microcarrier beads: An improved method for the preparation of cell monolayers for electron microscopy
Authors: Hogan M. E. , Hassouna H. I. , Klomparens K. L. 
Published: February 2005

AbstractCross‐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.
Size changes of polystyrene latex particles in the electron microscope under controlled physical conditions
Authors: Cermola Michele , Schreil Werner‐Hans 
Published: February 2005

AbstractIn 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.
Automated jet polishing of transmission electron microscope specimens for in situ straining
Authors: Hardiman B. , Clark W. A. T. , Wagoner R. H. 
Published: February 2005

AbstractA 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.
X‐ray microanalysis of plants containing the platinum group metals
Authors: Parsons Patrick J. , Farago Margaret E. 
Published: February 2005

AbstractIt has been demonstrated that Water hyacinths, grown hydroponically in a solution containing the platinum group metals, accumulate and concentrate some of these metals in their roots. Root samples were examined in a scanning electron microscope, equipped with an energy dispersive spectrometer (SEM‐EDS), and platinum was detected on the surface. Further examination in an electron microprobe analyser (EMPA), using both wavelength dispersive spectrometry (WDS) and EDS, show platinum localized in the epidermal region of the root. Ruthenium was detected in root material taken from plants that had accumulated the complexed metal ion from solution.
Use of uranyl acetate en bloc to improve tissue preservation and labeling for post‐embedding immunoelectron microscopy
Authors: Erickson Page A. , Anderson Don H. , Fisher Steven K. 
Published: February 2005

AbstractWe 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.
High resolution analysis of paired helical filaments in Alzheimer's disease
Authors: Wen G. Y. , Wisniewski H. M. 
Published: February 2005

AbstractResults of this comparative study indicated that electron microscopy of supra‐ultrathin sections provided the best resolution, revealing the subunit structures, globules (32 Å ± 4), and longitudinal bars (47 Å ± 6) of paired helical filaments (PHF). A three‐dimensional model of PHF substructure is therefore presented. The image of brightfield electron micrographs of isolated PHF positively stained with 2% phosphotungstic acid (PTA) also provided high resolution and revealed the presence of the beaded structures of these heavily stained filaments in the crossing‐over region of PHF. Noisy background of the negatively stained preparation of isolated PHF substantially reduced the resolution. Severe flattened morphology of this preparation further complicated the interpretation of image analysis. Darkfield electron micrographs offered high‐image contrast with low noise in the background clearly demonstrating the ropelike twisting configuration of PHF, but did not reveal the substructures of PHF. The tilting (±45°) analysis of these PHF prepared by uranyl acetate staining and rotary‐shadowing and unidirectional shadowing methods with platinum showed that these heavy metals were deposited on the top filaments (away from the carbon film on the grid) in the crossing‐over region of PHF.
Growing and embedding monolayer cells in situ in beem capsule caps for light and electron microscopy
Authors: Asafo‐Adjei Edward , Bernard Eugene F. , Hase Tatsuo 
Published: February 2005

AbstractA method of growing and embedding monolayer cells in situ on the inner surface of the Beem capsule for light and electron microscopy is described. The results demonstrate that wandering cells in tissue and collected cells in suspension are readily grown on the Beem capsule and embedded in situ by a slight modification of the routine embedding procedure. The method seems to be particularly suited for studies of interactions between growing monolayer cells and various substances, infectious agents, or other types of cells added during the incubation period, where disruption by scraping and pelleting, or enzymatic reaction to remove the cells, would prevent such data from being gathered. The method is also suited for light and electron microscopic studies of minute tissue or organs, such as dissected mosquito salivary glands, whose embedding by the routine procedure is difficult.