bluuebunny/crossref_metadata_2025_split huggingface dataset:
Receptor mobility and the cytoskeleton in some human leukemic cells
Authors: Temmink J.H.M. 
Published: June 2020

Introduction. Lymphoid cells will, under certain conditions, exhibit striking exemples of surface receptor movement upon exposure to specific ligands. The receptors will first assemble in a few small surface areas (patching) and eventually aggregate at one pole of the cell (capping), leaving practically no receptors of the same specificity elsewhere on the cell surface. For a number of reasons cytoskeletal elements, like microtubules and microfilaments, are thought to play an important role in the movement of the cell surface receptors. However, the exact mechanism by which the cytoskeleton has its facilitating or inhibiting effect on receptor mobility is still largely a matter of speculation.During an investigation on non-Hodgkin lymphoma's we obtained leukocytes from three patients with clinically different leukemia's, i.e. hairy cell leukemia (HCL), prolymphocytic leukemia (PLL), and chronic lymphocytic leukemia (CLL). These gave different results in capping tests with Concanavalin A (ConA) and with antibodies against total Ig (Alg).
Contractile proteins in the sieve tubes and laticifer cells of some sensitive mimosa species
Authors: Artemίsia Arraes-Hermans M. , Dalla Bernardina E. L. 
Published: June 2020

The purpose of this paper is to review our previous work with HMM binding and to demonstrate with some new findings that this technique can be used effectively to determine changes in the organizational states of the actin-like microfilaments which are responsible for cytoplasmic streaming in laticifer cells and for conduction of the stigmotropic stimulus in the cytoplasm of mature sieve elements. The species used were Mimosa rixosa Mart., M. asperata Linn., and Mimosa laticifera Rizz.The technique used was negative coloration of phloem exudate and cytoplasmic suspension of latex. We have identified actin filaments in phloem exudate and latex of higher plants on the basis of filament morphology, reaction of the filaments with rabbit skeletal muscle HMM to form arrowhead complexes, and the reversibility of the arrowhead reaction on addition of pyrophosphate. This is the first report dealing with the presence of actin in sieve elements. Some of the microfilament structures are specific components of the cytoplasm of mature sieve tubes.
Zinc iodide-osmium tetroxide reaction: its effect on the synaptic vesicles in locust neuromuscular junctions and its chemical basis
Authors: Reinecke M. , Walther Ch. 
Published: June 2020

The zinc iodide-osmium tetroxide reaction (ZIO) was first used in neurobiological research by Maillet (Bull. Ass. Anat. 53, 233; 1968). Subsequently several authors have shown that, under appropriate conditions, ZIO stains mainly the interior of synaptic vesicles. The substrate of this reaction is under discussion, since ZIO can also react with other subcellular structures in a variety of tissues, e. g. mitochondria, endoplasmic reticulum, dictyosomes and lysosomes. Additionally, in vitro substances as different as some aminoacids, catecholamines, aldehydes and phospholipids (Pellegrino de Iraldi, Experientia 33, 1; 1977) can yield black precipitations with ZIO.Our studies were done with the motor nerve terminals at the femoral retractor unguis muscle of the locust (Locusta migratoria). These terminals are chiefly the endings of excitatory motoraxons and are characterized by the presence of electron lucent vesicles and by an accumulation of mitochondria.
A novel technique for the isolation of transverse tubular membrane from dystrophic skeletal muscle
Authors: Sabbadini Roger , Scales Donald , Nixon Cecelia 
Published: June 2020

IntroductionA particularly high fraction of T tubular membrane is apparent in standard isolations of microsomes derived from dystrophic muscle. We describe here a method for separating vesicles of T tubules from vesicles of sarcoplasmic reticulum (SR). The method assumes that only SR membranes are capable of ATP-dependent Ca2+transport, and in the presence of the precipitating anion oxalate, the buoyant density of oxalate- filled SR exceeds that of non-calcium transporting membranes. These latter microsomes are tentatively identified as T tubular membrane based on both morphological and biochemical observations.MethodsAs described previously microsomes were isolated from dystrophic chicken pectoral is muscle. The crude microsomes were incubated for 10 min. at 37°C in a medium containing 20 mM MOPS (pH 6. 8), 2 mM CaCl2, 2 mM EGTA, 5 mM Mg-ATP, 80 mM K-oxalate. This was cooled to 5°C and a 30 ml aliquot was layered on a 4 ml cushion of 52% sucrose, 20 mM MOPS. The microsomes were centrifuged for 45 min. at 82, 500 g in a Beckman L5-50 ultracentrifuge.
Electron microscopical study on collagen of chondrosarcoma
Authors: Takagi Katsumasa , Honda Itsuo , Kitagawa Toshio , Usuku Gentaro 
Published: June 2020

The histological identification of the malignancy of a cartilaginous tumor is not always simple. The ultrastructural structure of the cartilage has been described in numerous reports but there are few dealing with chondrosarcoma. Present authors have been studying to discover definite characteristics of chondrosarcoma. In this study, we hope to discover the characteristics of chondrosarcoma by concentrating on the collagen fibers which are one of the main components of chondroid tumor.Ten cases of chondrosarcoma ranging from 14 to 65 years of age, were examined using both transmission electron microscope and scanning electron microscope, and their structures were compared with other chondroid tissues, taken from non-malignant cartilaginous tumor, normal conditioning articular cartilage, and the meniscus of the knee joint. Small pieces of the specimens were fixed in 3% glutaraldehyde buffered with Millonig's phosphate buffer, post-fixed in 1% osmium tetroxide and embedded in Epon 812. Sections cut by LKB ultramicrotome were stained by uranyl acetate and lead citrate and examined with an AKASHI-TRS-80 electron microscope. The preparations for the scanning electron microscopy were coated with carbon and gold after the critical point drying method.
Antioxidant suppression of blood-brain barrier disruption and demyelination in experimental optic neuritis
Authors: Ann Ellis E. , Guy John R. , Fitzsimmons Jeffrey R. , Beck Barbara L. 
Published: June 2020

Hydrogen peroxide (H2O2) has been shown to play a major role in disruption of the blood-brain barrier (BBB) and demyelination in experimental allergic encephalomyelitis (EAE), an animal model for multiple sclerosis (MS). Reactive oxygen species, H2O2 and superoxide, are discharged by inflammatory cells that infiltrate the central nervous system (CNS) in FAE. Hydrogen peroxide can be directly toxic or can be converted to hydroxyl radical and induce peroxidation of lipids such as myelin. Catalase and glutathione peroxidase are antioxidant enzymes which detoxify H2O2 to O2 and H2O.Strain-13 guinea pigs were sensitized with myelin basic protein and in vivo permeability of the BBB was monitored by serial magnetic resonance imaging (MRI) with gadolinium-DTPA (Gd-DTPA) and the Dixon method for suppression of orbital fat. MRI was initiated three days after antigenic sensitization and performed at four or seven day intervals thereafter. All sensitized animals developed Gd-DTPA enhanced lesions, indicative of permeability of the BBB, at 3-7 days after antigenic sensitization.
Ultrastructure of transplanted schistosome sporocysts in incompatible snails
Authors: Rivera E.R. , Jourdane J. 
Published: June 2020

The tropical parasitic disease schistosomiasis haematobium requires the snail vector Bulinus truncatus to successfully complete its life cycle. While in the snail, the parasite exists as a cercarial producing sporocyst. The infection of snails by the parasite is very specific, different subpopulations (strains) of parasites are not always compatible with snails from different geographic regions. It is not always known if the incompatibility is due to failure of penetration of snails by parasites or to subsequent destruction of sporocysts by infected snails. In these experiments, sporocysts from compatible sporocyst-snai1 infections were surgically transplanted into snails not compatible with the parasite.Egyptian snails (B. truncatus) which had been infected with the Egyptian strain of Schistosoma haematobium were dissected after five weeks. Sporocysts were removed from the hepatopancreas and surgically implanted into B. truncatus snails from Egypt (compatible), Morocco and Niger (incompatible). After four days, these snails were dissected and the transplanted sporocysts were prepared for electron microscopy. Each sample was also tested for glycogen contents by the Thiery Silver test.
High-Voltage Electron microscopy of Histoplasma capsulatum
Authors: Song M. J. , Edwards M. E. 
Published: June 2020

Histoplasma capsulatum (Hc) is a pathogenic fungus frequently involved in lung infections, especially in immunocompromised individuals such as AIDS patients. It has been the subject of numerous investigations by light, transmission, and scanning electron microscopy. However, these studies did not afford a clear picture of the He cell architecture, for which three-dimensional views of the cellular organelles are deemed necessary. For this purpose, we have studied yeast cells of He by means of techniques used in high—voltage electron microscopy (HVEM).Yeast cells of He grown at 37°C in appropriate culture media were fixed with glutaraldehyde-osmium in cacodylate buffer, dehydrated through an ethanol series and embedded in Epon-Araldite, according to standard procedures. Thick sections (0.25-0.5 μm), picked up on Formvar-coated slot-grids, were stained for 4 h at 50°C with uranyl acetate and lead citrate, and examined under the AEI EM7 Mk 1.2 MV Albany HVEM at an accelerating voltage of 1.0 MV.
Three-dimensional organization of neuronal and glial cell processes as revealed by HVEM stereoscopy
Authors: Kama Kiyoshi 
Published: June 2020

The Knowledges on the three dimensional (3D) organization and the morphometrical data of neuronal and glial cell processes are indispensable for the understanding of the function of the CNS.The light microscope has been widely used for the morphological study of neurons and glia cells however the limited resolution of the light microscope has precluded the precise observation of structural details of the complicated processes of these cells. In addition, the depth of focus of the light microscope is veryshallow. Although the problem of this fault of the light microscope can be overcome by the use of the X-ray microscope which enables imaging of the specimens of 500μm in thickness in the same focal plane the resolution of the X-ray microscope we have developed is about the same range as that of the light microscope. In contrast, the conventional electron microscope provides extremely detailed images of neuropile.
Ultrastructural effects of recombinant human hematopoietic stem cell factor on mast cells and basophils from human CD34+ pluripotent progenitor cells
Authors: Goff J.P. , Kirshenbaum A. S. , Albert J. P. , Kessler S.W. , Zsebo K. M. , Metcalfe D. D. 
Published: June 2020

Hematopoietic stem cell factor (SCF) is the product ofSllocus in the mouse and is the ligand for the protooncogenec-kit.The human homologue has recently been cloned and recombinant protein (rhSCF) expressed and purified to homogeneity. rhSCF is synergistic with human cytokines in promoting the proliferation and differentiation of human progenitor cells.Human mast cells and basophils have been shown to originate from human bone marrow-derived CD34+ pluripotent progenitor cells cultured in the presence of rhIL-3, and develop granule scroll patterns only when cocultured with mouse 3T3 fibroblasts. Mast cells, from CD34+ cells cultured over agarose surfaces, in the presence of rhIL-3 had granules that contained only homogeneously dense material. To determine the effect of rhSCF on the appearance of mast cells and basophils in culture, highly purified human CD34+ progenitor cells were grown in the presence of rhIL-3, rhSCF, or rhIL-3 in combination with rhSCF over agarose surfaces.
New cathodoluminescence spectral analysis and imaging equipment
Authors: Wright P. J. 
Published: June 2020

The examination of CL emission can provide a wealth of information from many widely differing materials when irradiated by the electron beam of an SEM. However, the requirements that need to be met by equipment designed to observe these signals differ widely depending on the application for which it will be used. Oxford Instruments have developed two CL systems which, in conjunction with cooling stages, can provide for the needs of the majority of CL researchers.The first is iciCL and it enables production of true colour digital images from many materials, although its major use has been in the study of geological materials and ceramics. Provision has also been made to allow the acquisition of CL spectra within the range 400 ≤ λ ≤ 700 nm and the generation of false colour and composite images.
HREM Study of electron-induced surface radiation damage in ReO3
Authors: Ai R. , Fan H.-J. , Marks L. D. 
Published: June 2020

It has been known for a long time that electron irradiation induces damage in maximal valence transition metal oxides such as TiO2, V2O5, and WO3, of which transition metal ions have an empty d-shell. This type of damage is excited by electronic transition and can be explained by the Knoteck-Feibelman mechanism (K-F mechanism). Although the K-F mechanism predicts that no damage should occur in transition metal oxides of which the transition metal ions have a partially filled d-shell, namely submaximal valence transition metal oxides, our recent study on ReO3 shows that submaximal valence transition metal oxides undergo damage during electron irradiation.ReO3 has a nearly cubic structure and contains a single unit in its cell: a = 3.73 Å, and α = 89°34'. TEM specimens were prepared by depositing dry powders onto a holey carbon film supported on a copper grid. Specimens were examined in Hitachi H-9000 and UHV H-9000 electron microscopes both operated at 300 keV accelerating voltage. The electron beam flux was maintained at about 10 A/cm2 during the observation.
In situ REM imaging of surface processes on ceramic bulk crystals from 300 to 1670 K in a conventional TEM
Authors: Wang Z. L. , Bentley J. 
Published: June 2020

Studying the behavior of surfaces at high temperatures is of great importance for understanding the properties of ceramics and associated surface-gas reactions. Atomic processes occurring on bulk crystal surfaces at high temperatures can be recorded by reflection electron microscopy (REM) in a conventional transmission electron microscope (TEM) with relatively high resolution, because REM is especially sensitive to atomic-height steps.Improved REM image resolution with a FEG: Cleaved surfaces of a-alumina (012) exhibit atomic flatness with steps of height about 5 Å, determined by reference to a screw (or near screw) dislocation with a presumed Burgers vector of b = (1/3)<012> (see Fig. 1). Steps of heights less than about 0.8 Å can be clearly resolved only with a field emission gun (FEG) (Fig. 2). The small steps are formed by the surface oscillating between the closely packed O and Al stacking layers. The bands of dark contrast (Fig. 2b) are the result of beam radiation damage to surface areas initially terminated with O ions.
Determination of interface width using EELS fine structure changes
Authors: Dravid Vinayak P. , Notis M.R. , Lyman C.E. 
Published: June 2020

The concept of interfacial width is often invoked in many materials science phenomena which relate to the structure and properties of internal interfaces. The numerical value of interface width is an important input parameter in diffusion equations, sintering theories as well as in many electronic devices/processes. Most often, however, this value is guessed rather than determined or even estimated. In this paper we present a method of determining the effective structural and electronic- structural width of interphase interfaces using low- and core loss fine structure effects in EELS spectra.The specimens used in the study were directionally solidified eutectics (DSEs) in the system; NiO-ZrO2(CaO), NiO-Y2O3 and MnO-ZrO2(ss). EELS experiments were carried out using a VG HB-501 FE STEM and a Hitachi HF-2000 FE TEM.
Lorentz electron microscopy of magnetic domains in rapidly solidified and annealed Pt-Co-B alloys
Authors: Qiu N. , Wittig J. E. 
Published: June 2020

PtCo hard magnets have specialized applications owing to their relatively high coercivity combined with corrosion resistance and ductility. Increased intrinsic coercivity has been recently obtained by rapid solidification processing of PtCo alloys containing boron. After rapid solidification by double anvil splat quenching and subsequent annealing for 30 minutes at 650°C, an alloy with composition Pt42Co45B13 (at.%) exhibited intrinsic coercivity up to 14kOe. This represents a significant improvement compared to the average coercivities in conventional binary PtCo alloys of 5 to 8 kOe.Rapidly solidified specimens of Pt42Co45B13 (at.%) were annealed at 650°C and 800°C for 30 minutes. The magnetic behavior was characterized by measuring the coercive force (Hc). Samples for TEM analysis were mechanically thinned to 100 μm, dimpled to about 30 nm, and ion milled to electron transparency in a Gatan Duomill at 5 kV and 1 mA gun current. The incident ion beam angle was set at 15° and the samples were liquid nitrogen cooled during milling. These samples were analyzed with a Philips CM20T TEM/STEM operated at 200 kV.
Microstructural characterization of InGaAs/GaAs quantum wells grown at low substrate temperatures
Authors: Sung C.M. , Elman B. , Ostreicher K.J. , Hefter J. , Koteles Emil S. 
Published: June 2020

The composition and thickness of InxGa1-xAs/GaAs quantum wells play an important role in the determination of their optical and electronic properties. InxGa1-xAs/GaAs single quantum wells (SQWs) grown at low substrate temperatures with various In compositions (x) and well thicknesses were investigated by reflected high energy electron diffraction (RHEED) and photoluminescence (PL) techniques to determine when the critical thickness for pseudomorphic growth was exceeded. Cross-sectional TEM methods were employed to directly determine the critical layer thickness of InGaAs on GaAs and the presence of the dislocations generated in these layers.The samples were grown by MBE on semi-insulating (100) GaAs substrates at substrate temperatures of 410°C and 460°C. They consisted of undoped SQWs and barriers in which the well width was varied from 1 nm to 22 nm. The In composition in the well layers was varied from 0.3 to 0.5. The growth rates and In compositions were deduced from RHEED intensity oscillation measurements . Cross-sectional specimens for TEM studies were prepared in the usual manner, by mechanical thinning followed by Ar+ ion milling. A Philips EM400T operated at 120 keV was used to observe the specimens.
Microanalysis of high-dose oxygen-implanted germanium
Authors: Kim M.J. , Zhang Q. , Das Chowdhury K. , Carpenter R.W. , Kelly J.C. 
Published: June 2020

High-dose ion implantation is being increasingly used to produce buried oxide layers in silicon for high speed CMOS and VLSI applications. Ion implantation into germanium has been used to control optical properties. Germanium implanted with high dose oxygen is a promising material for photodetectors and solar energy converters. In the present study the structural changes in germanium caused by high dose oxygen implantation, giving low reflectivity in the far-UV and visible, were characterized by HREM and high spatial resolution AEM.The single crystal n-type germanium {111} wafers were implanted with O+ ions to doses of lx1017 to 1.5xl018 cm-2 at 45 keV. The implantation temperature was estimated to be about 400°C. The absorption behavior of the implanted samples was measured by Infrared (IR) spectroscopy. The compositional profiles of implanted layers were obtained by Rutherford Backscattering Spectrometry (RBS) and position-resolved EELS. Cross-sectional TEM samples for microstructural characterization were prepared by mechanical polishing and ion milling. A Philips 400ST/FEG analytical microscope was used for nanoprobe experiments, at 100 kV. Microstructural investigation was performed using ISI-002B and JEM-2000FX microscopes, at 200 kV.
Multiple scattering and displacive modulation in the YBa2Cu3O7-δ system
Authors: Zhu Yimei , Suenaga M. , Moodenbaugh A.R. 
Published: June 2020

Using transmission electron microscopy, structure modulation associated with electron multiple scattering and diffuse scattering in oxygen reduced, and Fe and Co doped YBa2Cu3O7_δ has been studied. The modulated structure (tweed) exhibits [110] and roughly-periodic lenticular domain images (see Fig.l) and cross-shaped diffuse intensity in diffraction (see Fig.2). The overall diffraction pattern in the [001] zone has a 4-fold symmetry with diffraction intensity which falls off monotonically from one Brillouin zone to the next. Superimposed over each Bragg spot seem to be two cross-streaks of equal length in the [110] and directions.However, for a diffraction pattern in a high symmetry Laue case, one must consider the possibility of multiple scattering effects, whereby a diffracted electron beam acts as an incident beam. This can complicate diffuse scattering phenomena, even in a thin crystal. Careful inspection of Fig.2 reveals that the shapes of the diffuse scattering are not all identical at all diffraction spots.
Ultrastructural Changes in Schwann Cells of Peripheral Nerve of Diabetic Mice
Authors: Hanker J. S. , Carson K. A. , Ambrose W. W. , Yates P. E. , Bossen E. H. 
Published: June 2020

At 8 to 11 months of age inbred mice (C57BL/KsJ-db, The Jackson Laboratory) with an autosomal recessive disease resembling human diabetes mellitus show inconstant and intermittent symptoms of a sensory ataxia which is manifest by flexion and adduction of the hind limbs. When their peripheral nerves such as trigeminal ganglion and sciatic nerve are compared with those of unafflicted littermates, a marked proliferation of Schwann cells is observed. It was, therefore, of interest to compare ultrastructurally the sciatic nerves of the diabetic mice in this age range with those of unafflicted littermates with particular emphasis on the study of Schwann cells.Diabetic mice which exhibited ataxic symptoms and hind limb performance deficits in a rotating-wheel test and unaffected littermates were sacrificed by per cardium perfusion of saline followed by 3% glutaraldehyde in 0.1M cacodylate buffer pH 7.3.
Ultrastructural Changes Caused by Plant Cytokxnins on Dog Thyroid Follicular Cells “In Vitro”
Authors: Fernandez-Pol J. A. 
Published: June 2020

Plant cytokinins are a group of growth promoting hormones with pronounced metabolic and regulatory effects not only on plants but also on microbial and animal cells (l). The effects of the N6-substituted derivatives of adenine, especially Zeatin (trans-6-(4-hydroxy-3-methylbut-2-enyl)- aminopurine) and Kinetin (6-furfurylaminopurine) on ultrastructure and on the in vitro response to Thyrotropin (TSH) or 8Br-cyclic AMP were studied in dog thyroid follicular cells.Thyroid slices were incubated in the presence of Zeatin or Kinetin with and without TSH or 8Br-cyclic AMP, after 30min. prior incubation in Earle's solution. Effects on ultrastructure were observed after 30min. to 6hrs. of incubation. The thyroid slices after removal from incubation flasks were fixed immediately in 3%glutaraldehyde-formalin in 0.05M phosphate buffer. Specimens were then treated as described elsewhere (2). Observations were performed with a Siemens IA electron microscope.