bluuebunny/crossref_metadata_2025_split huggingface dataset:
Localization of Surfactant Phospholipids in the Peritoneal Mesothelium
Authors: Lloyd J. K. , Dobbie J. W. , Hauck W. N. , Manning K. A. 
Published: June 2020

The peritoneum consists of a monocellular layer of mesothelium supported by fibrous connective tissue of variable thickness. This tissue covers the walls of the abdominal cavity (parietal) and the surfaces of the abdominal organs, omentum and mesentery (visceral). A recent study has shown that the mesothelium synthesizes phosphatidylcholine which is the principle constituent of pulumonary surfactant phospholipids (1). Pulmonary surfactant is synthesized by Type II pneumocytes and stored in cytoplasmic structures called lamellar bodies. Tannic acid fixation has been shown to enhance preservation of these lamellar bodies (2). In the present study, samples of peritoneum from mice were prepared by tannic acid fixation and examined.CF1 mice were injected intraperitoneally with 1% tannic acid in a 2% glutaraldehyde solution (Sorensen's phosphate buffer). Tissues from the parietal peritoneum (anterior abdominal wall) and mesentery were removed and placed in the tannic acid/glutaraldehyde solution for 24 hours at 4°C. Tissues were post-fixed in 1% osmium tetroxide and embedded in Spurr.
Lung Parenchymal Response to Amosite Asbestos and Cigarette Smoke Exposure
Authors: Gray L. D. , Brady D. E. , Ford Joan O. 
Published: June 2020

Asbestos exposure in humans has been associated with a variety of debilitating and potentially fatal conditions including lung fibrosis, mesothelioma and lung cancer. Persons who have been exposed to asbestos and who also smoke cigarettes are at far greater risk of developing lung cancer than individuals who either smoke or are exposed to asbestos alone. The mechanisms of this synergistic effect are poorly understood at present and it is important that they be studied because many (if not most) individuals who occupationally work with asbestos also smoke cigarettes.The purpose of the present study was to investigate the parenchymal reaction to asbestos and smoke exposure in an animal model and to clarify the roles of epithelial cells and phagocytes in the ensuing pathologic response.Male Hartley outbred guinea pigs approximately 700 g each were divided into groups of 8 animals as follows. One group was exposed to 4 cigarettes per day, 5 days per week for a total of 8 weeks.
The Orientation of Sickle Hemoglobin Fibers Within Bundles as Determined by Correspondence Analysis
Authors: Lee T. E. , Carragher B. , Watowich S. J. , McDade W. A. , Josephs R. 
Published: June 2020

Sickle cell anemia results from the polymerization of deoxygenated sickle hemoglobin (HbS) into long helical fibers. In red blood cells, and in vitro, fibers aggregate and align to form bundles which eventually crystallize. The fiber bundles distort the red cells and have been implicated in the catalysis of the polymerization reaction. Although the structure of the HbS fiber has been extensively investigated, the packing of fibers in bundles and the fiber rearrangements which accompany crystallization are poorly understood, even though these phenomena are of interest at both a clinical and a basic level. We have used correspondence analysis to establish that during crystallization fibers separate into rows of particles oriented in opposite directions.Axial projections in opposite directions down the HbS fiber are different and are related by mirror symmetry. Thus they can be used to determine the particle orientation in or out of the plane of projection. Figure 1 shows these projections for models of an HbS fiber.
3-D Structure of Negatively Stained Chromatin Fibers
Authors: Woodcock C.L. , McEwen B.F 
Published: June 2020

In the eukaryotic nucleus, DNA is packaged into nucleosomes, and the nucleo- some chain folded into '30nm' chromatin fibers. A number of different model structures have been proposed for the arrangement of nucleosome within the fiber1 and most of these are based on helical symmetry. Indications of helical order have been observed over short regions of fiber but the structure is too disordered to allow reconstruction by Fourier methods. We have used tomography, an approach developed for asymmetric specimens, to prepare 3D reconstructions of chromatin fibers.Nuclei from Necturus maculosus erythrocytes were briefly digested with micrococcal nuclease, and the released chromatin fibers fixed with 0.1% gluta- raldehyde, and stained with 1.5% sodium phosphotungstate pH 7.0 containing 0.015. glucose. Tilt series were taken at 5° intervals from +70° to -70° using a Philips 420 EM at 100KV and 30,000x magnification. Straight regions of fiber showing indications of internal order were digitized with a pixel size of l.lnm, reconstruction carried out as described, and the final 3D data sets filtered to a resolution of 3.5nm.
Electron Beam Profile in the ESEM
Authors: Danilatos G. D. 
Published: June 2020

The examination of specimens in the presence of gas in the environmental scanning electron microscope (ESEM) requires the electron beam to pass through a minimum (optimum) 1ayer of gas before it strikes the specimen. The electron scattering by the gas molecules results in a modification of the original beam profile. Some conclusions from a study on these profiles are presented here but more details can be found elsewhere.When an electron beam travels a distance L through a gas with n particles per unit volume, the average number of collisions per electron m= σ⊤nL, where σ⊤ is the characteristic total collision cross section for the gas. The electron beam collision process is described by the Poisson distribution P (x) =mx e-m/X!, where P(x) is the probability that an electron undergoes x number of collisions (X=0, 1 ,2. . . ) . Thus, when m=1 , about 37% of electrons undergo no collisions, 37% undergo a single collision, 18% two collisions, 6%. three collisions etc.
Backscattered Electron Imaging of GaAs/AlGaAs Super Lattice Structures with an Ultra-High- Resolution SEM
Authors: Ogura Kazumichi , Kersker Michael M. 
Published: June 2020

Backscattered electron (BE) images of GaAs/AlGaAs super lattice structures were observed with an ultra high resolution (UHR) SEM JSM-890 with an ultra high sensitivity BE detector. Three different types of super lattice structures of GaAs/AlGaAs were examined. Each GaAs/AlGaAs wafer was cleaved by a razor after it was heated for approximately 1 minute and its crosssectional plane was observed.First, a multi-layer structure of GaAs (100nm)/AlGaAs (lOOnm) where A1 content was successively changed from 0.4 to 0.03 was observed. Figures 1 (a) and (b) are BE images taken at an accelerating voltage of 15kV with an electron beam current of 20pA. Figure 1 (c) is a sketch of this multi-layer structure corresponding to the BE images. The various layers are clearly observed. The differences in A1 content between A1 0.35 Ga 0.65 As, A1 0.4 Ga 0.6 As, and A1 0.31 Ga 0.69 As were clearly observed in the contrast of the BE image.
Low-Voltage Scanning Electron Microscopy Investigation of Polymers
Authors: Berry V. K. 
Published: June 2020

The morphological characterization of any polymer blend plays an important part in the development of a new blend system because the properties of blends are dictated by phase morphology which is dependent upon the chemistry and the processing conditions. Light microscopy, scanning electron microscopy and transmission electron microscopy are the most commonly used microscopical techniques for morphological characterization. Transmission electron microscopy techniques provide the best resolution (≈ 0.3 nm) but are limited in the size of sample area and require elaborate sample preparation procedures. Surface charging and beam damage problems have been some of the drawbacks of conventional scanning electron microscopy with non-conducting materials like polymers.The use of low accelerating voltage scanning electron microscopy (LVSEM) in the characterization of polymers and other non-conducting materials is beginning to be recognized.
High-Vacuum Evaporation and a Cryostage to Observe Fractured Yeast
Authors: Wergin William P. , Erbe Eric F. , Vigil Eugene L. 
Published: June 2020

Investigators have long realized the potential advantages of using a low temperature (LT) stage to examine fresh, frozen specimens in a scanning electron microscope (SEM). However, long working distances (W.D.), thick sputter coatings and surface contamination have prevented LTSEM from achieving results comparable to those from TEM freeze etch. To improve results, we recently modified techniques that involve a Hitachi S570 SEM, an Emscope SP2000 Sputter Cryo System and a Denton freeze etch unit. Because investigators have frequently utilized the fractured E face of the plasmalemma of yeast, this tissue was selected as a standard for comparison in the present study.In place of a standard specimen holder, a modified rivet was used to achieve a shorter W.D. (1 to -2 mm) and to gain access to the upper detector. However, the additional height afforded by the rivet, precluded use of the standard shroud on the Emscope specimen transfer device. Consequently, the sample became heavily contaminated (Fig. 1). A removable shroud was devised and used to reduce contamination (Fig. 2), but the specimen lacked clean fractured edges. This result suggested that low vacuum sputter coating was also limiting resolution.
Effects of Heat Shock on Nucleolar Organization in Tobacco Cells
Authors: Yen Y. H. , Chen Y. R. 
Published: June 2020

In the previous study, supraoptimal and lethal temperatures affected on the structure of cell organelles in root meristematic cells of soybean were reported(l). In the present study, nucleolar organization in cultured cells responsing to heat shock will be invastigated.Suspension culture cells of tobacco(Nicotiana tobaccumW 38) growing in MS medium containing 1 ppm 2,4-D and 1 ppm kinetin were divided into several groupes and incubated as follow: 1), 28°C(2h); 2), 38°C(2h); 3), 42°C(2h); 4), 45°C(2h); 5), actino- mycin D(2 ug/ml, 3h). After incubation, cells were collected, fixed in 3% glutaraldehyde, post-fixed in 1% osmic tetraoxide, dehydrated in ethanol series and embedded in Spurr's resin. Thin sections were collected on formvar-supported grids and stained with uranyl acetate and lead citrate. Silver-staining adopted the method of Medina et al.(2) and sample were prefixed in 3% glutaraldehyde, post-fixed in Carnoy's solution, and then impregnated with silver by 2-step method.
Application of Polyethylene Glycol (PEG) Embedding and Rotary-Replication Techniques to the Study of Photoreceptor Synaptic Ribbon Ultrastructure
Authors: Dickson D. Howard , WhitefieLd Stephan C. , Morrison Christine A. 
Published: June 2020

Synaptic ribbons (SRs) are electron-dense, LameLLar specializations found in the retina, inner ear and pineal. Although it has been suggested that SRs may have a functional role in the maintenance of synaptic terminal shape or in orienting synaptic vesicles to the presynaptic membrane neither hes been confirmed. Their intimate association with synaptic vesicles has however supported the Latter hypothesis. Controversy also exists with respect to diurnal rhythmicity of these organelles. Recently, a major advance in our knowledge of SR structure was achieved through the application of freeze-slamming and freeze-substitution techniques. However, the cost and complexity of these techniques, together with the Limitations imposed by freezing rate and ice-crystal damage has Led us to explore the use of the PEG-embedding technique to further our study of SRs in retina and pineal.Chick retinas were prepared following the technique of Kondo. Tissues were fixed in 2.5% glutaraldehyde in 0.1 M sodium cacodylate buffer containing 0.5% tannic acid at pH 7.4 for 2 hr, washed in buffer and postfixed in 1% OsO4 for 1 hr.
Biological Control of Postharvest Diseases of Fruit: Inhibition Of Botrytis Rot On Apple by an Antagonistic Yeast
Authors: Wisniewski M. , Wilson C. , Chalutz E. , Hershberger W. 
Published: June 2020

As an alternative to fungicides, biological control of postharvest diseases of fruit has recently met with good success with peaches and apples and is an area of great potential. In contrast to previous study, we were particularly interested in finding antagonists that did not produce antibiotics as part of their mode of action. After extensive screening, several yeast and bacteria were identified that exhibited biocontrol of a number of postharvest disease organisms. In particular, the yeast, Debaryomyces hansenii, indicated great potential as a biocontrol agent without exhibiting antibiotic production as a mode of action. It has been recently shown to effectively control decay on citrus caused by Penicillium digitatum, Penicilliim italicum and Geotrichum candidum. The present report is the first to document the use of D. hansenii to control postharvest decay of apples by Botrytis cinerea and present possible inodes of action.To test for biocontrol activity, apples (cv Golden Delicious) ware wounded with a 4 nm cork borer to a depth of 5 mm.
Microscopy studies of Tilletia controversa teliospore development in wheat ovaries and in culture
Authors: Hess W. M. , Trione E. J. 
Published: June 2020

Teliospore formation begins in wheat ovaries when they are about 0.5 mm diam. Tilletia controversa hyphal cells initially invade host cells intercellularly. During development a narrow band of sporogenous hyphal cells develop into reticulated teliospores without hyphal attachments. The host tissue is utilized in the formation of mature teliospores. Eventually a thin layer of host tissue surrounds the mature teliospores. In contrast, when the teliospores form in medium hyphal tips appear to enlarge into developing teliospores. Light microscopy, SEM, and thin sections with TEM were used to determine whether teliospores formed from enlarged hyphal tips or from sporogenous cells which fragment from hyphae.Teliospores were obtained from USDA ARS experimental plots at Logan, UT. Wheat plants were inoculated and grown in a greenhouse. Tissues were fixed for 1 h or longer in 2% glutaraldehyde, 3% acrolein, 0.1 M Na-cacodylate buffer, pH 7.3; rinsed several times in the same buffer; postfixed in 1% OsO4 in 0.1 M Na-cacodylate buffer, pH, 7.3 for 2 h in an ice bath; and rinsed in 0.1 M Na-cacodylate buffer prior to dehydration in a graded ethanol series.
The distribution of calcium and magnesium in developing tobacco leaves as measured by low-temperature X-ray microanalysis
Authors: Echlin Patrick 
Published: June 2020

The processes of leaf maturation and senescence are linked closely to the redirection of ions and organic nutrients between leaves and other part of the plant. It is known from work on whole leaves, that Ca2+ and Mg2+ play an important role in leaf development, although no studies have been made of changes at the cell and tissue level. This present study follows the cellular changes in Ca2+ and Mg2+ in the epidermal and photosynthetic tissues by X-ray microanalysis of frozen hydrated leaves.Full details of sample preparation, instrumentation, and the basis of the quantitative procedures have been reported elsewhere. Flat, frozen hydrated fracture faces of upper and lower epidermis; palisade and spongy mesophyll cells were analysed for Ca2+ and Mg2+. Data was collected from each of the four cell types in 20 different leaves at each of the following five stages of growth. Juvenile (10 weeks from seed); Mature (13 weeks), Ripe (16 weeks), Senescent (19 weeks) and Old (21 weeks). Cells containing obvious calcium oxalate crystals were avoided.
High-voltage electron microscopy of maxillary gland of spirochete-infected brine shrimp: lesion of efferent tubule
Authors: Tyson G. E. , Song M. J. 
Published: June 2020

Natural populations of the brine shrimp, Artemia, may possess spirochete- infected animals in low numbers. The ultrastructure of Artemia's spirochete has been described by conventional transmission electron microscopy. In infected shrimp, spirochetal cells were abundant in the blood and also occurred intra- and extracellularly in the three organs examined, i.e. the maxillary gland (segmental excretory organ), the integument, and certain muscles The efferent-tubule region of the maxillary gland possessed a distinctive lesion comprised of a group of spirochetes, together with numerous small vesicles, situated in a cave-like indentation of the base of the tubule epithelium. in some instances the basal lamina at a lesion site was clearly discontinuous. High-voltage electron microscopy has now been used to study lesions of the efferent tubule, with the aim of understanding better their three-dimensional structure.Tissue from one maxillary gland of an infected, adult, female brine shrimp was used for HVEM study.
Indirect immunogold labeling of methanol dehydrogenase in a methanotrophic and a methylotrophic bacterium
Authors: Fassel T.A. , Buchholz L.A. , Lidstrom M.E. , Schaller M.J. , Remsen C.C. 
Published: June 2020

Methanol dehydrogenase (MDH), is used by methanotrophic and methylotrophic bacteria to oxidize methanol to formaldehyde. (1) The enzyme is thought to exist both in a soluble form and in association with membrane. (2) Antisera prepared againstMethylomonas albusBG8 MDH andMethylobacteriumsp. strain AM1 MDH was used in an indirect Immunogold procedure to demonstrate localization of MDH. Following a modification of the method of De Mey (3), thin sections were incubated with primary antibody before exposure to gold-labeled secondary antibody.BG8, an obligate methanotroph, grows on methane and converts it to methanol. Methanol is then further oxidized by MDH to formaldehyde. A distinguishing feature of BG8 are extensive Intracytoplasmlc membranes (ICM) that form bundles or vesicular stacks located away from the peripheral membranes and extending into the cytoplasm (Fig. 1). (4) It is theorized that MDH is associated with ICM.
High-resolution immunogold labeling of cell surfaces: The hypothetical homodimeric nature of the cd5 receptor
Authors: de Harven E. , Christensen H. 
Published: June 2020

Molecules exposed on cell surfaces and labeled with colloidal gold markers can be optimally demonstrated using the backscattered electron imaging (BEI) mode of the scanning electron microscope (SEM). Steric hindrance, however, limits labeling efficiency, making it necessary to use gold markers of small size for labeling at the molecular level. Using a JEOL 840 SEM equipped with a lanthanum hexaboride (LaB6) cathode, 13 nm gold particles were demonstrated. This, however, seems to represent the limit of the resolution of this type of instrument in the BEI mode. Fortunately, it has been demonstrated by Walther and Muller that 5 nm gold particles can be seen in the BEI mode, using field emission SEM.We have confirmed this observation, using the JEOL 890 field emission SEM and a solid state backscattered electron detector. Human peripheral blood lymphocytes prefixed with 0.1% glutaraldehyde, incubated with the murine monoclonal antibody LEU-1 (CD5), were labeled with a goat anti-murine IgG adsorbed on 5 nm gold particles (GAM-G5, Janssen Pharmaceutica, Beerse, Belgium) according to previously described procedures.
Image analysis of 2-D Na,K-ATPase crystals maintained in vitreous ice
Authors: Misra Manoj , Beall Harry C. , Taylor Kenneth A. , Ting-Beall H.P. 
Published: June 2020

The molecular description of the Na,K-ATPase in the native state at high-resolution is required for the detailed description of the mechanism by which the active transport of Na and K ions occurs. Our efforts, therefore, are directed toward obtaining this molecular description by means of electron microscopy of ordered arrays of Na,K-ATPase molecules preserved in the frozen-hydrated state in amorphous ice.The procedure for crystallization of Na,K-ATPase was similar to that of Mohraz et al. Electron microscope grids for cryo-microscopy were prepared essentially as described by Dubochet et al. Frozen-hydrated specimens were examined in the Philips 420 electron microscope using a Gatan model 626 Cryotransfer system and cooling holder. Micrographs were recorded at 36000X under minimal dose conditions. Electron micrographs of frozen-hydrated membranes were screened initially by optical diffraction and examined for the presence of 4-6 rows of crystal lattice without any discernible visual disorder.
Unbiased estimation of particle number and sizes using the new stereological tools: the disector, the fractionator, the selector, and the nucleator — or just point-sampled intercepts
Authors: Gundersen H.J.G. 
Published: June 2020

Previously, all stereological estimation of particle number and sizes were based on models and notoriously gave biased results, were very inefficient to use and difficult to justify. For all references to old methods and a direct comparison with unbiased methods see recent reviews.The publication in 1984 of the DISECTOR, the first unbiased stereological probe for sampling and counting 3—D objects irrespective of their size and shape, signalled the new era in stereology — and give rise to a number of remarkably simple and efficient techniques based on its distinct property: It is the only known way to obtain an unbiased sample of 3-D objects (cells, organelles, etc). The principle is simple: within a 2-D unbiased frame count or sample only cells which are not hit by a parallel plane at a known, small distance h.The area of the frame and h must be known, which might sometimes in itself be a problem, albeit usually a small one. A more severe problem may arise because these constants are known at the scale of the fixed, embedded and sectioned tissue which is often shrunken considerably.
TEM studies of amorphization processes and amorphous structures
Authors: Mitchell T. E. , Schwarz R. B. 
Published: June 2020

Traditional oxide glasses occur naturally as obsidian and can be made easily by suitable cooling histories. In the past 30 years, a variety of techniques have been discovered which amorphize normally crystalline materials such as metals. These include [1-3]:Rapid quenching from the vapor phase.Rapid quenching from the liquid phase.Electrodeposition of certain alloys, e.g. Fe-P.Oxidation of crystals to produce amorphous surface oxide layers.Interdiffusion of two pure crystalline metals.Hydrogen-induced vitrification of an intermetal1ic.Mechanical alloying and ball-milling of intermetal lie compounds.Irradiation processes of all kinds using ions, electrons, neutrons, and fission products.We offer here some general comments on the use of TEM to study these materials and give some particular examples of such studies.Thin specimens can be prepared from bulk homogeneous materials in the usual way. Most often, however, amorphous materials are in the form of surface films or interfacial films with different chemistry from the substrates.
The characterization of amorphous Al2O3by extended energy loss fine structure (EXELFS) analysis
Authors: Sklad P. S. , Angelini P. , Sevely J. 
Published: June 2020

Amorphous phases have been shown to influence properties of many metallic, semiconducting, and ceramic materials. However, analysis of these phases presents a difficult challenge since most conventional characterization techniques provide only limited qualitative information. Extended Energy Loss Fine Structure (EXELFS) analysis is a technique which is sensitive to both structure and composition within near neighbor distances of specific types of atoms in both crystalline and amorphous materials. The fine structure, which is present in the form of modulations on the core loss edges of electron energy loss spectra, results from diffraction of ejected core electrons by neighboring atoms. The ability to obtain EXELFS measurements with an analytical electron microscope allows direct observation of changes in composition, microstructure, and local atomic environment at a spatial resolution (<100 nm) not attainable by other techniques.Recently an investigation of the effects of ion implantation on the microstructure and properties of A12O3has revealed differences in the response of various forms of amorphous A12O3to post-implantation annealing.