bluuebunny/crossref_metadata_2025_split huggingface dataset:
Immunogold and immunoblot studies on a cell surface protein found in primary mesenchyme cells and in the cortical secretory vesicles of the sea urchin egg
Authors: Decker G.L. , Valdizan M.C. 
Published: June 2020

A monoclonal antibody designated MAb 1223 has been used to show that primary mesenchyme cells of the sea urchin embryo express a 130-kDa cell surface protein that may be directly involved in Ca2+ uptake required for growth of skeletal spicules. Other studies from this laboratory have shown that the 1223 antigen, although in relatively low abundance, is also expressed on the cell surfaces of unfertilized eggs and on the majority of blastomeres formed prior to differentiation of the primary mesenchyme cells.We have studied the distribution of 1223 antigen in S. purpuratus eggs and embryos and in isolated egg cell surface complexes that contain the cortical secretory vesicles. Specimens were fixed in 1.0% paraformaldehyde and 1.0% glutaraldehyde and embedded in Lowicryl K4M as previously reported. Colloidal gold (8nm diameter) was prepared by the method of Mulpfordt.
Ultrastructure of giant cell tumor of the lung
Authors: Sun C.N. 
Published: June 2020

Multinucleated giant cells resembling osteoblasts seen in giant-cell tumors of bone have been described in the thyroid gland, and pancreas. However, a giant cell tumor of the lung with osteoblast-like cells is rare. The present report will describe ultrastructural aspects and histiogenesis of this type of lung tumor.A 58-year old white male patient was noted by chest x-ray to have a mass in the right lower lobe of the lung. Segmental resection of the superior segment was performed revealing a nodular neoplastic lesion of 3.5 cm in diameter located 4.3 cm from the bronchial resection margin. For EM preparation, the tissue samples were immediately fixed in 4 percent phosphate-buffered glutaraldehyde and postfixed 1 hr with 1 percent osmium tetroxide in phosphate buffer (pH 7.2), dehydrated in ethanol and embedded in Epon 812. The tumor presented a sheet-like growth pattern without evidence of encapsulation.
Ultrastructural observations of lung neoplasms induced in the strain A/J mouse by benzo(a)pyrene and ethylnitrosourea
Authors: Gunning W.T. , Stoner G.D. , Goldblatt P.J. 
Published: June 2020

The current literature regarding the histogenesis of mouse lung adenomas suggests two alternative cells of origin for these tumors. The Type II pneumocyte was accepted by most investigators as the cell which proliferated either spontaneously or by chemical induction, until Kauffman and co-workers reported histologic and ultrastructural features of a Clara cell adenoma, and indicated that in Swiss mice, 63% of all chemically induced tumors appeared to be Clara cell derived. Ward et al. using immunocytochemical techniques have demonstrated that all lung adenomas they tested in B6C3F1, BALB, and A strain mice appear to be of alveolar cell origin. It has also been reported that up to 70% of ethylnitrosourea induced adenomas can be characterized as Clara cell based on histochemical staining for nitroblue tetrazolium reductase.Histological investigation of lung tumors arising in Strain A/J mice from bioassays of thirteen chemicals demonstrates a variable growth pattern.
A light and electron microscopic examination of novel features of fish granulomas
Authors: Dykstra M.J. , Noga E.J. 
Published: June 2020

A typical mammalian granuloma resulting from chronic inflammation is primarily composed of plasma cells, lymphocytes, macrophages, monocytes and giant cells. So-called epithelioid cells are usually found in granulomas of immunological origin and are derived from the mononuclear phagocyte series. Epithelioid cell granulomas are associated with a number of infectious diseases of man such as tuberculosis, schistosomiasis and fungal infections such as coccidioidomycosis.Tissues from Atlantic menhaden and Tilapia fish were fixed in 10% formalin and stained with hematoxylin and eosin (H&E) for light microscopy. Replicate samples were fixed with McDowell's and Trump's fixative, embedded in Spurr's resin, sectioned, stained with uranyl acetate and lead citrate and examined with a transmission electron microscope.Three fish granulomas were examined: 1) A granuloma of unknown origin in a menhaden spleen (Figs. 1,2); 2) A granuloma induced by fungal hyphae in a menhaden with ulcerative mycosis (Figs. 3,4); and 3) A granuloma due to mycobacteriosis in Tilapia (Figs. 5,6).
Toxic effects of inhaled DMMP on the kidneys of Fischer-344 rats
Authors: Mattie D.R. , Hixson C.J. 
Published: June 2020

Dimethylmethylphosphonate (DMMP) is a simple organophosphate used industrially as a flame retardant and to lower viscosity in polyester and epoxy resins. The military considered the use of DMMP as a nerve gas simulant. Since military use of DMMP involved exposure by inhalation, there was a need for a subchronic inhalation exposure to DMMP to fully investigate its toxic potential.Male Fischer-344 rats were exposed to 25 ppm or 250 ppm DMMP vapor on a continuous basis for 90 days. An equal number of control rats were sham-exposed. Following the 90-day continuous exposure period, 15 male rats were sacrificed from each group. Two rats from each group had the left kidney perfused for electron microscopic examination. The kidneys were perfused from a height of 150 cm water with 1% glutaraldehyde in Sorensen's 0.1M phosphate buffer pH 7.2. An additional kidney was taken from a rat in each group and fixed by immersion in 2.5% glutaraldehyde and 2% paraformaldehyde in 0.1M cacodylate buffer pH 7.4. A portion of the 9 kidneys collected for electron microscopy were processed into Epon 812. Thin sections, stained with uranyl acetate and lead citrate, were examined with a JEOL 100B Transmission Electron Microscope. Microvilli height was measured on photographs of the cells of proximal tubules. This data, along with morphologic features of the cells, allows the proximal convoluted tubules (PCT) to be identified as being S1, S2, or S3 segment PCT.
A scanning electron microscopic study of the eggs of Culicoides variipennis (Diptera: Ceratopogonidae)
Authors: Nunamaker R. A. , Nunamaker C. E. , Wick B. C. 
Published: June 2020

Culicoides variipennis (Coquillett) is probably the most economically important species of biting midge in the U.S. due to its involvement in the transmission of bluetongue (BT) disease of sheep, cattle and ruminant wildlife, and epizootic hemorrhagic disease (EHD) of deer. Proposals have been made to recognize the eastern and western populations of this insect vector as distinct species. Others recommend use of the term “variipennis complex” until such time that the necessary biosystematic studies have been made to determine the genetic nature and/or minute morphological differences within the population structure over the entire geographic range of the species. Increasingly, students of ootaxonomy are relying on scanning electron microscopy (SEM) to assess chorionic features. This study was undertaken to provide comparative chorionic data for the C. variipennis complex.Culicoides variipennis eggs were collected from a laboratory colony maintained in Laramie, Wyoming.
The Ultrastructure of Galago senegalensis cerebellar cortex
Authors: Milliken G. , Lavallee K. , Lamoreaux W. , Rosell-Davis R. , Ward J. 
Published: June 2020

The insectivorous, nocturnal prosimian, Galago senegalensis (bushbaby), relies on its arboreal running and leaping ability for survival, and extreme hand-eye coordination for prey capture. In mammals, these functions require a well developed motor system mediated by a highly evolved cerebellum. The mammalian cerebellar cortex is characterized by a three layer configuration comprised of the molecular, Purkinge, and granular layers. In this study, we examined the ultrastructure of the cerebellar cortex of the bushbaby.A six year old male bushbaby was anesthetized with 2 cc sodium pentobarbitol injected intraperitoneally. The animal was perfused through the superior vena cava by flushing the system with saline and 2% heparin, followed by fixation with 2% glutaraldehyde for 30 min. After primary fixation, the animal was decapitated and the head placed in 2% glutaraldehyde overnight. The brain was removed and desired areas were excised from the brain, post-fixed with osmium tetroxide, dehydrated in acetone, and embedded in Epon Araldite.
Expression of bovine coronavirus antigens at the plasma membrane in infected cell cultures
Authors: Payne H. R. 
Published: June 2020

Infection by bovine coronavirus (BCV) may cause severe diarrhea in neonatal calves. The virus can multiply in the human adenocarcinoma cell line HRT-18 and in bovine fetal spleen cells (BFS). Fusion of BFS cells occurs after BCV infection if trypsin is added to the culture medium. This type of fusion may be induced by other enveloped viruses following the expression of virally encoded macromolecules in the plasma membrane. The presence of viral proteins in the host plasma membrane is not, however, necessary for BCV maturation since coronaviral particles are enveloped by budding into intracellular compartments. Immunogold techniques were used to determine if BCV proteins are present in the plasma membrane of the host cell and whether their absence might explain the lack of fusion in BFS cells not treated with trypsin.Monolayers of HRT-18 cells, grown in DMEM medium with 5% fetal calf serum, were infected with BCV.
Acetaminophen: Macula densa hypersecretory activity by induced hepatotoxicity
Authors: Poolsawat S.S. , Huerta C.A. , Lae S.TY. , Miranda G.A. 
Published: June 2020

Introduction. Experimental induction of altered histology by chemical toxins is of particular importance if its outcome resembles histopathological phenomena. Hepatotoxic drugs and chemicals are agents that can be converted by the liver into various metabolites which consequently evoke toxic responses. Very often, these drugs are intentionally administered to resolve an illness unrelated to liver function. Because of hepatic detoxification, the resulting metabolites are suggested to be integrated into the macromolecular processes of liver function and cause an array of cellular and tissue alterations, such as increased cytoplasmic lysis, centrilobular and localized necroses, chronic inflammation and “foam cell” proliferation of the hepatic sinusoids (1-4).Most experimentally drug-induced toxicity studies have concentrated primarily on the hepatic response, frequently overlooking other physiological phenomena which are directly related to liver function. Categorically, many studies have been short-term effect investigations which seldom have followed up the complications to other tissues and organs when the liver has failed to function normally.
Ultrastructure of yeast plasma membrane revealed by a new high-resolution freeze-replica method
Authors: Hirano Tadashi , Tanaka Akira 
Published: June 2020

The Freeze-fracture morphology of the plasma membrane and surface of yeast protoplasts has been investigated by a new high resolution freeze-replica method (Tanaka et al.1978). According to freeze-fracture theory, it is generally argued that the plane of cleavage breaks down into the bilayer and then follows the plane of the membrane between the two halves of the lipid. However, when we observed thin sections of replica film of the surface of the freeze-fractured face of intact yeast cells, the single unit membrane was clearly visible between the replica film and the cytoplasm (Fig. 1). Accordingly, in the case of yeast cells, we assume that the plane of cleavage breaks down between the plasma membrane and cell wall.On the other hand, Walzthöng et al. (1982) have shown that surface granules are an artifact or form of contamination produced under the conditions used for the ordinary freeze-replica method employing metal shadowing film.
Warm and freeze-fracture of cotton seed radicles
Authors: Vigil E. L. , Erbe E. F. 
Published: June 2020

In cotton seeds the radicle has 12% moisture content which makes it possible to prepare freeze-fracture replicas without fixation or cryoprotection. For this study we have examined replicas of unfixed radicle tissue fractured at room temperature to obtain data on organelle and membrane structure.Excised radicles from seeds of cotton (Gossyplum hirsutum L. M-8) were fractured at room temperature along the longitudinal axis. The fracture was initiated by spliting the basal end of the excised radicle with a razor. This procedure produced a fracture through the tissue along an unknown fracture plane. The warm fractured radicle halves were placed on a thin film of 100% glycerol on a flat brass cap with fracture surface up. The cap was rapidly plunged into liquid nitrogen and transferred to a freeze- etch unit. The sample was etched for 3 min at -95°C to remove any condensed water vapor and then cooled to -150°C for platinum/carbon evaporation.
Crystallization intermediates of sickle hemoglobin
Authors: Gabriel Barbra L. , Josephs Robert 
Published: June 2020

Sickle hemoglobin (HbS) polymers can crystallize through different pathways determined by the solution conditions. Fibers are the first polymers to form Above pH 6.5 in 50 mM phosphate buffer (the high pH pathway), fibers form fas cicles, which consist of large arrays of fibers. The fibers in fascicles become progressively more ordered and ultimately crystallize. Below pH 6.5 (the low pH pathway), fibers form macrofibers which align and crystallize. The different intermediates are similar in being composed of double strands of HbS and in forming structurally identical crystals.In this work, HbS polymerization near the boundary of the high and low pH pathways was investigated. The experiments were conducted over a pH range of 6.1 to 7.2 in 20 to 100 mM phosphate buffer. The solutions were periodically assayed at frequent intervals (3 to 15 min), and the structures present at each time point characterized in the electron microscope. The experiments were concluded when the HbS crystallized.
Magnetic microlens focusing of electron beams
Authors: Terris B. D. , Rugar D. 
Published: June 2020

Recently, field emission sources in combination with either magnetic or electrostatic microlenses have been predicted to produce electron beams with high brightness and low aberrations. The key advantage to such systems is the short focal length and thus small coefficients of spherical and chromatic aberration. In addition, by using either small apertures or extremely sharp emission sources, the emission angle can be made small and thus the effect of the aberrations reduced further. We present here our initial results on building a magnetic microlens system. The unique feature of this work is the use of permanent magnets as the sole focusing elements in the lens, resulting in an extremely simple and inexpensive system.It has been shown that the aberrations in a focused electron beam can be reduced by selectively scaling the column dimensions. The focused spot sized is limited by the spherical aberrations,and the chromatic aberrations
Holographic contrast transfer theory
Authors: Plass R. , Marks L. D. 
Published: June 2020

With the advent of reliable cold field emission transmission electron microscopes there is substantial interest in using the amplitude and phase information recorded in electron holograms to optically or numerically correct for the coherent aberrations of transmission electron microscopes. However electron holography cannot compensate for incoherent aberrations. The derivation of the contrast transfer function for off axis electron holography in this paper shows there is no fundamental improvement in resolution for electron holography over conventional transmission electron microscopy.Evaluating the contrast transfer function involves mathematically following an electron beam through a field emission electron microscope set up for off axis electron holography. Due to the high coherence of the field emission electron beam coherent aberrations caused by the pre-specimen beam focusing system must be accounted for. Starting with a spacial frequency distribution, C(v), for the electron beam leaving the gun, the electron beam is limited by the condenser aperture and coherently aberrated by the condenser lens and objective pre-field as it passes to the specimen region:
Architecture of butterfly scales: Pattern formation by single cells
Authors: Ghiradella Helen 
Published: June 2020

Scales, the fine “dust” that covers the wings and bodies of butterflies and moths, are extremely complex in form. Like the wings and the rest of the exoskeleton they are made of non-living cuticle. Each is the product of a single cell and as such represents pattern formation on a microscopic level, all the more remarkable in view of the great variety in forms that scales may take.On the wing, the scales are usually arranged in rows of alternating long cover scales and shorter ground scales (Figure 1). The ground scales are usually unspecialized and show typical scale architecture: each is essentially a flattened sac whose lower lamina (the surface hidden from view) is smooth and featureless, while the visible upper lamina is elaborated into a gridwork of parallel longitudinal ridges joined at intervals by transverse crossribs (Figure 2). Ridges and ribs together frame rows of windows that open into the interior of the scale. The interior is usually empty except for pillar-like trabeculae which join the upper and lower laminae.
Biomineralization:New directions in crystal science
Authors: Heywood Brigid R 
Published: June 2020

The development of effective protocols for the reproducible control of crystal structure, size and morphology is attracting considerable interest given the requirement for particles of modal size and shape in many areas of materials fabrication and the importance of crystallochemical selectivity in determining the exploitable properties (eg. optical, magnetic, electrokinetic) of inorganic solids. In biological systems their are many examples of advanced “crystal engineering” in which inorganic solids are deposited in a highly controlled manner to produce mineral phases that are unique with respect to their structure, habit, and uniformity of size (Figures 1 & 2). The crystallochemical specificity of such biogenic solids (eg. calcium phosphates, calcium carbonates, iron oxides, barium and strontium sulphates) is tailored to a wide variety of both structural (eg. bones and teeth) and non-structural roles. Examples of the latter include pH homeostasis, the transduction of magnetic signals and inertial detection.A review of biomineralization will show that while a complex array of strategies have evolved for regulating the formation of crystalline phases, one feature is common to the continuum of mechanisms; interactions between organized biopolymeric assemblies and the nascent inorganic solids play a fundamental role in controlling the deposition of the biomineral.
Application of the Omega spectrometer TEM
Authors: Lehman J. L. , Mayer J. , Probst W. 
Published: June 2020

The recent development of an analytical TEM with an integrated imaging Omega spectrometer has opened the door to a new world of specimen information. The Omega Spectrometer eliminates some of the information limits which have been imposed by the chromatic aberration effects in thick 3-D specimen imaging, as well as thermal diffuse and inelastic scattering in electron diffraction studies. This benefits both the TEM 3-D imaging and electron diffraction fields.Inelastically scattered electrons are electrons which have lost some of their energy while passing through the specimen. In all conventional TEMs, these inelastically scattered electrons inherently cause the final image to be blurry as the objective lens focuses the different energies into different image planes. The chromatic aberration of the objective lens can be calculated by the simple equation, Δc = Cc.α.ΔE/E, where ΔE is the energy spread of the electrons leaving the specimen, and E is the energy of the electrons entering the specimen. The chromatic aberration of the objective lens can be reduced by increasing the value of E or limiting ΔE.
Evaluation of the biocompatibility of polymer surface modifications with the corneal endothelium
Authors: Citron R. , Tunberg B. , Yamada A. 
Published: June 2020

Early studies of the interactions of intraocular lens (IOL) implant materials with corneal endothelial cells showed that momentary contact during surgery could result in permanent damage to these cells. It was also demonstrated that this damage could be prevented by providing a protective barrier between the intraocular lens substrate and the endothelium. This barrier might be in the form of a permanent or dissolvable coating, or introduction of a hydrophilic viscoelastic to the anterior chamber of the eye prior to implantation. It is desirable to examine this effect in vitro when developing new IOL materials or surface modifications. The technique developed for this purpose provides an improvement over previous methods, in that momentary contact and the forces involved are computer controlled for consistency, and image analysis may be used in quantifying the amount of damage.The computer controlled test instrument designed and built at IOLAB brings the test material and a rabbit eye corneal endothelial surface into contact with a specified load, time, and stage speed.
Dental porcelain repair: a scanning electron microscopy study
Authors: Perdigao Jorge , Suliman Abdul-Haq , Swift Edward 
Published: June 2020

Due to its lasting esthetic results, the use of percelain has been increasing in Dentistry. Porcelain has two main disadvantages: it is vulnerable to shear stresses and is difficult to repair. When fractures occur, they must be repaired intraorally. Since it is not feasible to repair porcelain with the same material, a bonding system is needed for effective repair, using resin composites. Several techniques have been advocated to create microporosities on the porcelain surface, allowing the formation of a mechanical interlocking with a resin material: roughening with a diamond bur, intraoral sandblasting, and acid-etching with hydrofluoric acid (HF). A silane has been used as a coupling agent between polymers and inorganic substances for the last 40 years. It was introduced as a dental material in the early 60's.The purpose of this project was to evaluate the effect of four different porcelain surface topographies treated with four different bonding systems, on the morphology and bond strengths of porcelain bonded to a hybrid resin composite (AP H).
Atomic force microscopy (AFM) of the topography of silicon surfaces exposed to ion beams
Authors: Denker Mark , Wall Jennifer , Ray Mark , Linton Richard 
Published: June 2020

Reactive ion beams such as O2+and Cs+are used in Secondary Ion Mass Spectrometry (SIMS) to analyze solids for trace impurities. Primary beam properties such as energy, dose, and incidence angle can be systematically varied to optimize depth resolution versus sensitivity tradeoffs for a given SIMS depth profiling application. However, it is generally observed that the sputtering process causes surface roughening, typically represented by nanometer-sized features such as cones, pits, pyramids, and ripples. A roughened surface will degrade the depth resolution of the SIMS data. The purpose of this study is to examine the relationship of the roughness of the surface to the primary ion beam energy, dose, and incidence angle. AFM offers the ability to quantitatively probe this surface roughness. For the initial investigations, the sample chosen was <100> silicon, and the ion beam was O2+.Work to date by other researchers typically employed Scanning Tunneling Microscopy (STM) to probe the surface topography.