bluuebunny/crossref_metadata_2025_split huggingface dataset:
Tissue printing for scanning electron microscopy and microanalysis
Authors: Reine Barbara A. 
Published: June 2020

The study of plant morphology and plant cells in the scanning electron microscope is often compromised by the limitations of specimen preparation techniques. Simple natural dehydration usually results in unacceptable shrinkage and distortion of the normal surface morphology of plant cells. Chemical fixation followed by critical point drying or some substitute for critical point drying such as Peldri II or HMDS (hexamethyldisilazane) improves morphological results but still imparts artifacts, adds chemical constituents to the specimen, and requires the use of toxic chemicals, a hood, and much time.One technique that eliminates many of these disadvantages and is even suitable for specimen preparation in the field is tissue printing. For low magnification imaging and chemical analysis its “elegant simplicity” (2) is compelling. Historically, the application of tissue printing has been in connection with optical microscopy (1,2). However, this technique works very well for low magnification SEM and associated elemental characterization of residues by x-ray microanalysis.
Immunocytochemical localization of nicotine in developing leaves of two cultivars ofNicotiana tabacum
Authors: Echlin Patrick 
Published: June 2020

Improved techniques have been developed for thein situlocalization of nicotine in developing leaves ofNicotiana tabacum. Earlier studies had shown that aldehyde fixed and partially dehydrated material embedded in different hydrophillic resins at low temperatures, retained up to 50% of the nicotine but invariably at the expense of good structural preservation. Significant improvements have now been made to the methods and it is now possible to obtain excellent structural preservation with high retention of nicotine.Tobacco plants were grown in a glasshouse maintained at 23-26°C with 16H light and were well watered and fed with a high nitrogen fertilizer. The flower heads were removed from the plants as they appeared. Samples were taken from between the main veins at a distance 10mm from the edge of the mid part of the leaf at 10, 13, 16, 20, and 22 weeks from the time of seed germination which corresponded to the Juvenile, Mature, Ripe, Senescent and Old stages of leaf development.
Intelligent computational 3-D microscopy: New results in segmentation, noise removal, cell counting, and automated neuron tracing
Authors: Roysam Badrinath , Bhattacharjya Anoop K. , Ancin Hakan , Cohen Andrew R. , Mackin Robert W. , Becker Douglas E. , Rodriguez Carlos 
Published: June 2020

This paper presents a review of recent advances made by us in the broad area of intelligent computational 3-D microscopy. This research involves the development and application of automated pattern recognition, computer vision and image interpretation algorithms to problems in 3-D biological microscopy. The broad goal of this work is to develop computational tools for rapid, unsupervised, flexible, quantitative and unbiased analysis of large sets of complex 3-D images of thick biological specimens. The imaging modalities used in this work have thus far involved laser-scanning confocal microscopy (LSCM) and 3-D brightfield microscopy. The specimens of interest have been thick slices of brain tissue, large selectively-stained neurons, indocyanin green and fluorescein retinal angiograms, and duck overlapping cell clusters in cytological preparations such as Papanicolaou smears.Image segmentation is an essential first step for most forms of analysis. This task is straightforward when the image data is isotropic, has uniform high contrast, and is free of noise.
Video-microscopic measurement of cell-substratum traction forces generated by locomoting keratocytes
Authors: Oliver Tim , Leonard Michelle , Lee Juliet , Ishihara Akira , Jacobson Ken 
Published: June 2020

We are using video-enhanced light microscopy to investigate the pattern and magnitude of forces that fish keratocytes exert on flexible silicone rubber substrata. Our goal is a clearer understanding of the way molecular motors acting through the cytoskeleton co-ordinate their efforts into locomotion at cell velocities up to 1 μm/sec. Cell traction forces were previously observed as wrinkles(Fig.l) in strong silicone rubber films by Harris.(l) These forces are now measureable by two independant means.In the first of these assays, weakly crosslinked films are made, into which latex beads have been embedded.(Fig.2) These films report local cell-mediated traction forces as bead displacements in the plane of the film(Fig.3), which recover when the applied force is released. Calibrated flexible glass microneedles are then used to reproduce the translation of individual beads. We estimate the force required to distort these films to be 0.5 mdyne/μm of bead movement. Video-frame analysis of bead trajectories is providing data on the relative localisation, dissipation and kinetics of traction forces.
Brefeldin A affects the endomembrane system and vesicle trafficking in higher plants
Authors: Satiat-Jeunemaitre Béatrice , Henderson Jancy , Evans David , Crooks Kim , Fricker Mark , Napier Richard , Hawes Chris 
Published: June 2020

In plant cells, as in animal cells, many macromolecules and membranes are transported by vesicle vectors through both the exocytotic and endocytotic pathways. In order to elucidate the mechanisms and molecular events of such trafficking we are using a set of drugs known to perturb membrane flow in plant cells in combination with immunocytochemical studies using a bank of monoclonal antibodies to various components of the endomembrane system and cell surface. In animal cells, one such drug, Brefeldin A, a fungal fatty acid derivative which causes disruption of the Golgi apparatus, has recently been used as a tool to dissect the mechanisms of vesicle flow from the endoplasmic reticulum to the Golgi apparatus and down the cisternae of the Golgi stack (1). It has been demonstrated that BFA also has a dramatic effect on the Golgi apparatus in higher plant cells (2,3,4).In this paper we report on recent work on the disruption of the plant Golgi apparatus with BFA and the redistribution of endomembrane marker epitopes after drug treatment of roots and suspension culture cells.
Gender determination of caucasoid hair using image analysis
Authors: Ball T.B. , Hess W.M. 
Published: June 2020

It has been demonstrated that cross sections of bundles of hair can be effectively studied using image analysis. These studies can help to elucidate morphological differences of hair from one region of the body to another. The purpose of the present investigation was to use image analysis to determine whether morphological differences could be demonstrated between male and female human Caucasian terminal scalp hair.Hair samples were taken from the back of the head from 18 caucasoid males and 13 caucasoid females (Figs. 1-2). Bundles of 50 hairs were processed for cross-sectional examination and then analyzed using Prism Image Analysis software on a Macintosh llci computer. Twenty morphological parameters of size and shape were evaluated for each hair cross-section. The size parameters evaluated were area, convex area, perimeter, convex perimeter, length, breadth, fiber length, width, equivalent diameter, and inscribed radius. The shape parameters considered were formfactor, roundness, convexity, solidity, compactness, aspect ratio, elongation, curl, and fractal dimension.
Confocal scanning laser microscopy applied to quantify gap junction expression and discriminate different connexin isoforms
Authors: Gourdie Robert G , Green Colin R , Thompson Robert P , Rothery Stephen , Peters Nicholas S , Severs Nicholas J 
Published: June 2020

The principles of confocal scanning laser microscopy, and the ability of the technique to provide serial optical sections free from out-of-focus blur for three-dimensional image reconstruction, are now well known to most microscopists. Current studies have entered a new phase — how best to exploit the high definition digital images for maximizing information in specific research applications. Here we report methods for the quantitative analysis of gap junction content per unit volume of tissue and per cell, and for qualitative analysis of the expression of different gap junctional proteins (connexins) in the heart.The first requirements for developing these methods are properly characterized antibodies that, under standardized conditions, give reproducible results in immunofluorescence staining protocols. The strategy as applied to cardiac gap junctions takes account of the unique organization of the junctions into intercalated disks at the end-on abutments between myocytes. Serial optical sectioning techniques are used to prepare projections revealing the entire gap junction population of en face-viewed disks.
Pyospermia and spermophagy in semen of the red wolf
Authors: Koehler James K. , Platz Carrol C. , Waddell Will , Jones Michael H. 
Published: June 2020

The red wolf (Canis rufus) inhabited the Southeastern United States until the early 1900's when aggressive hunting and a shrinking primitive habitat virtually eradicated the species. C. rufus was certified as an endangered species in 1967 and was essentially extinct in the wild by 1980. About 200 animals are preserved in zoos and captive breeding facilities where efforts are underway to increase the stock. Since a shrinking gene pool and captive stress may reduce reproductive vigor, we undertook an electron microscopic examination of red wolf semen used for artificial insemination at the Graham, WA breeding facility of the Point Defiance Zoo.Animals were anesthetized with 175 mg. Telazol, IM before electroejaculation using a rectal probe Semen was washed in PBS prior to fixation in 1.25% glutaraldehyde in 0.1 M cacodylate, post fixed in OsO4, dehydrated in alcohol and propylene oxide and embedded in Epon 812. Some samples were incubated in capacitation or maintenance media for several hours before fixation as above.
Confocal and Electron Microscopy of cultured cardiac myocytes
Authors: Simpson D.G. , Price R.L. , Terracio M. , Terracio L. , Borg T.K. 
Published: June 2020

Early in heart development cardiac myocytes are spherical in shape, intercellular junctions are distributed at irregular intervals around the periphery of the cell, and myofibrillar organization is essentially random. As myocytes mature, they undergo extensive morphogenesis during which the phenotype changes to a tubular rodlike shape, cell junctions congregate at the distal ends of cells to form intercalated disks, and myofibrils become organized in parallel arrays typical of striated muscle. Although not fully understood, it is known that these changes are a result of interactive processes between intracellular components of the cytoskeleton, integrin membrane receptors, and the extracellular matrix (ECM).In vivo studies on the process of cardiac myocyte maturation and myofibrillogenesis are difficult because of the complex biochemical environment of the intact animal and the many extra- and intracellular interactions which are required for proper development and myofibrillogenesis. Unfortunately, in previously available in vitro modelling systems, isolated myocytes spread out over the culture substratum, assume a stellate nonpolar shape, and myofibril organization remains essentially random.
High-resolution SEM studies of the attachment of Giardia trophozoites to the microvillous border of cultured intestinal epithelial cells
Authors: Gavin Muriel , Wells Carol L. , Erlandsen Stanley L. 
Published: June 2020

Trophozoites or the free-swimming form of the intestinal protozoan,Giardia, resides within the host small intestine where they attach to the microvillous border by means of a grasping organelle, the ventral adhesive disc. Several mechanisms have been proposed to explain trophozoite attachment including contractile activity, microtubular coiling-uncoiling, hydryodynamic activity of the ventral flagella, and activated lectin binding.We have developed a model for investigating the mechanism of attachment ofGiardiatrophozoites to the microvillous border of cultured intestinal epithelial cells. Caco-2 cells, a human colonic intestinal cell line was grown for 14 days on glass cover slips in Delbeccos' modified Eagle's medium.Giardiatrophozoites (Be-1;IP-0482:1) were cultured in TYI medium for 3 days, then harvested and resuspended in modified Eagle's medium prior to incubation for 30 minutes on Caco-2 cells. Coverslips were rinsed with warm Hanks balanced salt solution, fixed overnight in 3% glutaraldehye - 0.1 M cacodylate buffer, pH 7.2, dehydrated in ethanol, and critical point dried in CO2.
Appearance of myofibroblast during the healing of experimental corneal wound
Authors: Ishizaki Masamichi , Wakamatsu Kyoko , Matsunami Takakuni , Yamanaka Nobuaki , Saiga Toshikazu , Kao Winston W.-Y. 
Published: June 2020

It is well known that corneal stroma cells (keratocytes) can transform to fibroblasts during the corneal wound healing. We have studied the expression of α-smooth muscle actin, vimentin and desmin in fibroblastic cells of the alkali-burneo and lacerated corneas in the rabbits by means of immunohistochemistry and electron microscopy.Methods. Rabbits were anesthetized, and central corneal alkali-burn and laceration were produced. The injured corneas healed for 1 day to 45 days, and 18 days embryonic rabbit corneas were immunostained with monoclonal antibodies against α-smooth muscle actin, vimentin and desmin. For transmission electron microscopy, two techniques were used for the staining of ultra-thin sections: 1) uranyl acetate and Reynold's lead citrate and 2) the tannic acid method of Kajikawa.Results. Antibody against α-smooth muscle actin reacted with fibroblastic cells in injured corneas (Fig 1) but not with stromal cells in normal and embryonic corneas. Antivimentin antibody strongly reacted with the fibroblastic cells in injured corneas (Fig 2) and stromal cells in normal and embryonic corneas.
Effects of Higher-Order Laue Zone reflections on structure images
Authors: Kim H. S. , Sheinin S. S. 
Published: June 2020

The importance of image simulation in interpreting experimental lattice images is well established. Normally, in carrying out the required theoretical calculations, only zero order Laue zone reflections are taken into account. In this paper we assess the conditions for which this procedure is valid and indicate circumstances in which higher order Laue zone reflections may be important. Our work is based on an analysis of the requirements for obtaining structure images i.e. images directly related to the projected potential. In the considerations to follow, the Bloch wave formulation of the dynamical theory has been used.The intensity in a lattice image can be obtained from the total wave function at the image plane is given by:

where ϕg(z) is the diffracted beam amplitide given by
In these equations,the z direction is perpendicular to the entrance surface, g is a reciprocal lattice vector, the Cg(i) are Fourier coefficients in the expression for a Bloch wave, b(i), X(i) is the Bloch wave excitation coefficient, ϒ(i)=k(i)-K, k(i) is a Bloch wave vector, K is the electron wave vector after correction for the mean inner potential of the crystal, T(q) and D(q) are the transfer function and damping function respectively, q is a scattering vector and the summation is over i=l,N where N is the number of beams taken into account.
Analysis of photographic emulsions for High-Voltage Electron Microscopy
Authors: Kremer James R. , Furcinitti Paul S. , O’Toole Eileen , Richard McIntosh J. 
Published: June 2020

Characteristics of electron microscope film emulsions, such as the speed, the modulation transfer function, and the exposure dependence of the noise power spectrum, have been studied for electron energies (80-100keV) used in conventional transmission microscopy. However, limited information is available for electron energies in the intermediate to high voltage range, 300-1000keV. Furthermore, emulsion characteristics, such as optical density versus exposure, for new or improved emulsions are usually only quoted by film manufacturers for 80keV electrons. The need for further film emulsion studies at higher voltages becomes apparent when searching for a film to record low dose images of radiation sensitive biological specimens in the frozen hydrated state. Here, we report the optical density, speed and relative resolution of a few of the more popular electron microscope films after exposure to 1MeV electrons.Three electron microscope films, Kodak S0-163, Kodak 4489, and Agfa Scientia 23D56 were tested with a JEOLJEM-1000 electron microscope operating at an accelerating voltage of 1000keV.
Modulation electron energy loss spectroscopy and its application of quantitative analysis
Authors: Luo Suichu , Dunlap John R , Joy David C 
Published: June 2020

Electron energy loss spectroscopy (EELS) gives an inportant insight into the variety of excitations a sample may undergo when irradiated by an electron beam. The focus of this work was to simulate electronic excitations within the energy range from a few to several hundred eV. Our recently developed modulation scheme, combines both convolution and deconvolution techniques, to provide quantitative information about elementary inelastic scattering processes without knowledge of sample parameters such as thickness or optical constants.In the low energy loss region of the spectrum the primary excitation mechanisms include interband transitions, and surface and bulk plasmons. In general these individual excitation events overlap in the spectrum. A FFT convolution procedure was developed where the basic inelastic processes may be represented by the dielectric theory . The dielectric function ε is used to describe both single excitations and collective excitations, whereHere ωp2=4πNe2/m is the bulk plasmon frequency, N is number of free electrons per unit volume, e and m are the charge and mass of the electron respectively and ω0is a constant which is finite for a bound state but zero for a free electron.
Determination of refractive index of solids by dispersion staining method: An analytical approach
Authors: Su Shu-Chun 
Published: June 2020

When immersion liquids are used to determine the refractive index (RI) of non-opaque solids, the dispersion staining method is a simple, effective and precise way to determine the matching wavelength, λ0, at which the RI of an immersion liquid equals that of the solid. A series of equations has been derived to calculate the RI at any given visible wavelength such as nF, nD and vie, i.e. the RI’s at Fraunhöfer spectral lines F (486 nm), D (589 nm), and C (656 nm), from λ0 data obtained by the dispersion staining method. Two methods have been established: the Single Liquid Method and the Double Liquid Method.The Single Liquid Method is applicable for solids with known dispersion coefficients, which is defined as (nF-nC). This method uses only one immersion liquid whose RI is close to the RI of the solid to be measured so that a match between the liquid and the solid occurs in the visible range.
High-resolution field emission SEM of bulk biological samples: Relationship between different metal coatings, their thicknesses, and quality of backscatter electron versus secondary-electron imaging
Authors: Frethem Chris , Wells Carol , Carlino Vince , Erlandsen Stanley L. 
Published: June 2020

High resolution visualization of cell surfaces in bulk biological samples can be obtained by low voltage FESEM using either SE or BSE imaging methods and the preferred selection of low accelerating voltages (1-4 keV) has been based on theoretical considerations related to interaction volumes, electron charge, and potential radiation damage to the surface produced by direct exposure to the electron beam. Fine metal coatings (≤1 nm) produced by ion sputtering for high resolution FESEM imaging are used to minimize charging and to increase SE contrast as well as BSE topographical contrast.The purpose of this work was to investigate the relationship between the thickness of metal coatings produced by ion beam sputtering and the quality of imaging obtained by SE and BSE of biological samples. Cells of Proteus mirabilus were immunocytochemically labeled with 12 nm colloidal gold as previously described, fixed in glutaraldehyde followed by post-fixation in osmium, and critical point dried in CO2.
A comparative SEM study of the release of three herpes virus progeny
Authors: Moninger Thomas , Rodriguez Jose 
Published: June 2020

Human foreskin (HF) cells are permissive for three members of the herpesvirus family: herpes simplex virus (HSV), varicella-zoster virus (VZV) and human cytomegalovirus (HCMV). HSV and VZV belong to the alphaherpesvirinae subfamily, HCMV to the betaherpesvirinae. Cultures of the human melanoma line known as MEWO were also infected with VZV and HSV. The viruses cause different diseases in human beings.In their interaction with cultured HF cells, HSV, VZV and HCMV differ in the effect they have on cell morphology (normally elongated), on the length of their replication cycle, and in the period of time during which progeny infectious virions are released, if they are released, since, unlike HSV and HCMV, infectious VZV virions are found only in small numbers in extracellular fluid from infected cultures. These observations led us to use scanning electron microscopy (SEM) to do a comparative study of progeny virion release with HF cells infected with one of the three herpesviruses under study.
Measurement of the geometric properties of lineal features in 3-D microstructures
Authors: DeHoff R.T. 
Published: June 2020

In most applications of stereology the focus of the measurements is upon the volume fraction Vv, surface area density Sv and number density Nv of three dimensional features like particles, grains, cells, porosity, organelles, etc. Most microstructures contain features that are essentially one dimensional; their characterization is largely ignored.This presentation reviews the geometric properties that may be defined for space curves and edges in microstructures and the stereological relationships that, in an appropriately designed sampling scheme, provide unbiased estimates of these geometric properties.Space curves have a length, usually reported as a line length density, Lv in stereological analyses. The local geometry near a point on a space curve is characterized by two properties, the curvature k, which is the rate of rotation of the tangent vector along the are length, and the torsionτ, which is the rate of rotation of the binormal vector.Edges are space curves formed by the intersection of two surfaces.
Quantitative AFM of langmuir-blodgett films
Authors: Viswanathan R. , Garnaes J. , Schwartz D. K. , Zasadzinski J. A. N. 
Published: June 2020

Because of their applications in the areas of non-linear optics, molecular electronics, and biosensors, Langmuir-Blodgett (LB) films have been extensively studied by a wide variety of scattering and spectroscopic techniques. The atomic force microscope has emerged as an important tool for studying LB films because of its unprecedented ability to quantitatively measure films with high resolution.The unique abilities of quantitative AFM imaging motivated us to investigate the effect of incorporating different divalent metal cations and fatty acids of different chain length into films deposited on both amorphous and ordered substrates. Once substrate effects have been accounted for, multilayer Langmuir-Blodgett films of palmitic, stearic and arachidic acid salts show that the area per molecule is primarily controlled by the detailed interactions of the counterion with the carboxylic acid group. However, the lattice dimensions and symmetry are dictated by the close packing of the alkane chains, given the constraint of area per molecule set by the counterion.