Life Sciences Commons^™

Colloidal Gold Labelling Of Fibrinogen Receptors In Epinephrine – And Adp–Activated Platelet Suspensions, J. A. Oliver, R. M. Albrecht

Scanning Microscopy

It has been generally accepted for over twenty years that epinephrine stimulates platelet aggregation without inducing shape change. However, it has been recently reported that discoid platelets are not recruited into ADP-or epinephrine-stimulated aggregates. Previous work in our laboratory has suggested that platelet shape change is necessary for the binding of fibrinogen to its surface receptor, which is a prerequisite for platelet aggregation. These studies seem to indicate that epinephrine-induced platelet aggregation does involve shape change. To investigate this possibility, the extent of shape change and fibrinogen binding in suspensions of epinephrine-and ADP-activated and control platelets was assessed by scanning …

Light And Electron Microscopic Localization Of Glycoconjugates With Gold-Labeled Reagents, J. Roth

Scanning Microscopy

This paper gives an overview of the use of lectins, glycoproteins, monoclonal anticarbohydrate antibodies, toxins, and glycosyltransferases for the detection and localization of cellular glycoconjugates in sections from embedded tissues by light and electron microscopy. In all these techniques particles of colloidal gold were used as a marker. For light microscopic studies routine conditions of embedding such as paraffin or Epon embedding could be employed. For electron microscopic studies the low temperature embedding technique using Lowicryl K4M was found to be the method of choice for the localization of sugar residues in intracellular compartments, the extracellular matrix and the plasma …

Scanning Electron Microscopy Study Of Particles Generated By Laser Damage Of Aluminum Surfaces, L. L. Levenson, S. D. Traynor, G. A. Brost, F. Ziembo

Scanning Microscopy

A high intensity iodine laser (1.315 μm wavelength) was used to study laser-surface damage in vacuum. A 22mm diameter laser beam containing 3.9 J of energy was focused to a 1 mm spot on an aluminum plate mounted in a vacuum chamber. The laser pulse width was 7 μs (FWHM). A copper strip mounted on a quarter circle plate 3.5 cm from the laser spot was used to collect particles ejected from the surface. A scanning electron microscope (SEM) was used to measure the size and spatial distribution of the particles collected on the copper strip. It was found that …

The Scanning Electron Microscopy/Replica Technique And Recent Applications To The Study Of Fossil Bone, Timothy G. Bromage

Scanning Microscopy

The SEM/replica technique employs high resolution replica materials in order to reflect microstructural details of specimens, such as fossil bones, which cannot be observed directly. The described technique is simple, provides excellent resolution, is maximally adaptable to field and laboratory settings, and is applicable to large and topographically complex bone surfaces. The advent of the technique has made it largely possible to address certain issues in anthropology and paleontology. These contributions have principally been concerned with taphonomy as the study of the bone damage process, and bone biology as it relates to bone growth remodeling processes characterizing the facial growth …

Quantitative Analysis Of Occlusal Microwear In Australopithecus And Paranthropus, Frederick E. Grine

Scanning Microscopy

Quantitative analysis of microwear features preserved on the occlusal surfaces of the M²s of southern African specimens of Australopithecus and Paranthropus (the so-called 'gracile' and 'robust' australopithecines) reveals that there is no striking relationship in either taxon between occlusal facet inclination and the incidence of wear features. Within each taxon, Phase I and Phase II facets tend to differ in a similar manner in the total number of wear features, the percentage frequency of pitting, and in the orientation of wear scratches. Nevertheless, Paranthropus molars tend to display significantly greater numbers of microwear features on both Phase I …

Scanning Electron Microscopy Of Early Dinosaur Egg Shell Structure: A Comparison With Other Rigid Sauropsid Eggs, Frederick E. Grine, James W. Kitching

Scanning Microscopy

Fossil eggs attributable to dinosaur (probably prosauropod) parentage that have been recovered from the early Jurassic Elliot Formation sediments at the Rooidraai locality possess shells that are similar to those of birds and crocodilians, and distinctly unlike those of chelonians and gekkonids. The preserved shell is very thin, and distinct mammillary processes are lacking, although the inner surface displays an undulating contour. The absence of these processes may be attributable to the inner portion of the shell having been at least partially decalcified during incubation and not preserved in the fossil state. The shells appear to be composed of broadly …

Analysis Of Primate Dental Microwear Using Image Processing Techniques, Richard F. Kay

Scanning Microscopy

This paper introduces Fourier transformation as a rapid, replicable means for characterizing and distinguishing patterns of microscopic wear on primate teeth. The two-dimensional power spectra obtained from numerical Fourier transformation are shown to be different between two test patterns, one of which is composed of linear features and the other of randomly-spaced dots. A comparison is made, using Fourier transformation, of dental microwear patterns of small samples of two primate species, Ateles geoffroyi, the spider monkey, and Chiropotes satanas, the bearded saki. Ateles, with a scratch-dominated pattern of microwear, has a Fourier transform resembling that of the …

Morphological Characterization Of Materials Using Low Voltage Scanning Electron Microscopy (Lvsem), Jesse Hefter

Scanning Microscopy

The use of lower energy (0.5 to 10 keV) electron beams in the scanning electron microscope (LVSEM) provides a number of advantages in the imaging of materials, including increased topographic contrast and reduced specimen charging. Application of LVSEM to materials analysis was difficult in the past due to a number of instrumental difficulties, including low gun brightness, the increased effect of chromatic aberration upon lower energy beams, and the increased sensitivity of such electron beams to stray fields. Improvements in design have led to commercial instruments which provide the microscopist with the capability to analyze materials in this low-energy regime. …

Scanning Electron Microscopy Of Dentin Caries. Experimental In Vitro Studies With Streptococcus Mutans, Patrick A. Adriaens, Geert W. Claeys, Jan A. De Boever

Scanning Microscopy

This study was performed to gain better insight into the mechanisms involved in carious destruction of human dentin by Streptococcus mutans. In particular, bacterial colonization of dentin surfaces and bacterial invasion in dentin were studied.

Streptococcus mutans (S. mutans), strain NCTC 10449, was grown on sterile dentin blocks in a 10% CO₂ atmosphere at 37°C. After 72, 120, 144 and 288 h of incubation the specimens were processed for scanning electron microscopic examination. The colonization of the dentinal surface progressed slowly and was nearly complete after 288 h. Invasion of S. mutans into the dentinal tubules …

Scanning Electron Microscope Evaluation Of Drilling Damage And Acid Treatment Using Uncoated Core, D. R. Rothbard, R. A. Skopec, C. J. Bajsarowicz, T. H. Fate

Scanning Microscopy

A novel SEM technique allows the observation of the same pore on a core face after each step in a series of dynamic flow tests. It requires no conductive coating and facilitates core flow using a one inch (25.4 mm) diameter plug. Three separate studies were undertaken in which the procedure was used to observe the effects of drilling mud invasion, waterflooding, and matrix acidization on individual grains and pores. In the drilling mud study it was found that 2% HF removed most of the siderite weighted mud, but that mud residue and etching of the framework grains resulted in …

Replication Technique For Studying Microstructure In Fossil Enamel, A. D. Beynon

Scanning Microscopy

The present paper describes a two stage impression technique using a silicone elastomer suitable for field replication studies; which requires high dimensional stability, defined resolution, and being capable of reproducing inaccessible details. A test object consisting of etched pearlite possessed fine detail [>1μm to <0.1μm] which was suitable for testing negative/ positive replica combinations. Coltene President light-body impression material was capable of resolving parallel side depressions of widths ≧0.2μm, and it possesses very good dimensional stability with time, allowing the production of positive casts to be deferred for several months. Low viscosity Spurr resin reproduced this detail, and flowed into inaccessible sites.

Although there was evidence of bulk contraction on curing, there was no significant shrinkage on flat [linear] surfaces or in vertical relief dimensions.

Replicas of fractured hominid teeth showed good surface detail, and reproduction of inaccessible three-dimensional features on enamel surfaces. Enamel prism shape was pattern 3.

A Preliminary Study Of The Role Of Gastrointestinal Endocrine Cells In The Maintenance Of Villous Structure Following X-Irradiation, M. G. Wyatt, S. P. Hume, K. E. Carr, J. C. L. Marigold

Scanning Microscopy

The mechanism of gastrointestinal villous damage following ionizing irradiation is complex. Various compartments within the gastrointestinal tract have in turn been considered important for the maintenance of normal villous structure. To date, however, evidence for a single overriding regulator of epithelial well-being is lacking.

In this study, the role of the gastrointestinal (enteroendocrine) cells is explored and comparison made between endocrine cell number and villous structure.

Experiments were organised using hath control and irradiated groups of mice. Two time points (1 and 3 days) and three radiation doses (6, 10 and 18Gy) were employed. A simple method for endocrine cell …

Magnetic Domain Observation Using Spin-Polarized Scanning Electron Microscopy, K. Koike, H. Matsuyama, H. Todokoro, K. Hayakawa

Scanning Microscopy

A new apparatus, spin-polarized scanning electron microscope (SEM), has been developed. This is a unique apparatus, which forms images by electron spin polarization. By using this device, magnetic domain images can be obtained because secondary electrons from ferromagnetic samples are polarized representing the magnetization of the sample originating point. This method provides new capabilities, such as magnetic contrast independent of surface morphology, detection of magnetization direction, and high spatial resolution.

Electron Beam Induced Current Analysis Of Voltage Breakdown Sites In Thin Mos Oxides, J. Reimer, A. Battacharyya, K. Ritz

Scanning Microscopy

Voltage breakdown sites on thin (< 100 A) MOS capacitors have been identified by the electron beam induced current (EBIC) technique, using a scanning electron microscope (SEM). EBIC spots coincide with voltage breakdown locations and their image intensity can be changed by varying the applied bias or the electron beam accelerating voltage. Total current and the number of EBIC spots were the same in both accumulation and depletion conditions for a fixed beam potential and bias voltage. This suggests that the observed EBIC spots were due to defects in the oxide only. This EBIC method for identifying defects has been found very useful in characterizing thin MOS oxides.

Characterization Of Oxidized Zinc (Calamine) Ores By Scanning Electron Microscopy And Electron Microprobe Analysis, G. Bonifazi, P. Massacci

Scanning Microscopy

Textural and structural features of Sardinian oxidized zinc (calamine) ores have been established by scanning electron microscopy and electron microprobe analysis, the elements analyzed being Zn, Pb, Ca and Fe. The surface composition of grains produced by comminution has also been determined, especially with reference to the presence of smithsonite and cerussite.

The methodological approach adopted has revealed intimate intergrowth of the mineral species present and contamination of the main mineral by inclusions of other species, which explains why it is so difficult to obtain good recoveries and high-quality concentrates by beneficiation processes.

Colloidal Gold - A Powerful Tool In Scanning Electron Microscope Immunocytochemistry: An Overview Of Bioapplications, G. M. Hodges, J. Southgate, E. C. Toulson

Scanning Microscopy

Colloidal gold may be conjugated to a wide variety of macromolecules, provides a versatile system for immunocytochemical studies by various types of microscopy (light and fluorescent microscopy, scanning (SEM) and transmission (TEM) electron microscopy), and is significantly contributing to the development of SEM immunocytochemistry as a routine analytical procedure.

A comprehensive overview has been compiled of the literature on SEM bioapplications of colloidal gold. This is illustrated through a selected series of studies focussing on a) cell surface receptor-ligand interactions; b) expression of cell surface lectin-binding sites; c) surface distribution of extracellular matrix components; and d) visualization of gold-labelled cytoskeletal …

Recent Advances In Scanning Electron Microscope Cathodoluminescence Assessment Of Gaas And Inp, C. A. Warwick

Scanning Microscopy

The capabilities of the cathodoluminescence mode of the scanning electron microscope are reviewed, with particular reference to the low temperature wavelength dispersive system in the author's own laboratory. The design of the luminescence collection optics is highlighted. The interpretation of the luminescence spectra is discussed in terms of the physics of radiative recombination. We offer some solutions to some of the main experimental problems with illustrations drawn from two case studies. The first is a study of the elimination of dopant striations in dislocation-free germanium doped indium phosphide and the second an analysis of the causes of threshold voltage scattering …

Surface Characterization Of Biomaterials By Immunogold Staining - Quantitative Analysis, Kinam Park, Scott R. Simmons, Ralph M. Albrecht

Scanning Microscopy

The labeling of target proteins by immunogold particles has been analyzed based on Einstein's law of Brownian motion. The theory was confirmed from the experiments which employed antifibrinogen gold markers to label fibrinogen molecules adsorbed on the polyethylene surface. The theory predicts that the degree of labeling depends on the concentration of gold markers, temperature, medium viscosity, size of gold markers, and staining time. Of these factors most important is the concentration of immunogold particles. Small change in the marker concentration results in a significant variation in the staining efficiency when other variables are kept constant. The effect of temperature …

Applications Of Cathodoluminescence Of Quartz And Feldspar To Sedimentary Petrology, Leslie F. Ruppert

Scanning Microscopy

Cathodoluminescence (CL), the emission of visible light during electron bombardment, was first used in sandstone petrology in the mid-1960's. CL techniques are especially useful for determining the origin and source of quartz and feldspar, two of the most common constituents in elastic rocks. CL properties of both minerals are dependent on their temperature of crystallization, duration of cooling, and/or history of deformation. Detrital quartz and feldspar are typically derived from igneous and metamorphic sources and luminesce in the visible range whereas authigenic quartz and feldspar form at low temperatures and do not luminesce. Quantification of luminescent and non-luminescent quartz and …

The Contribution Of Electron Probe X-Ray Microanalysis (Epxma) To Pollution Studies, A. J. Morgan, C. Winters

Scanning Microscopy

This paper surveys the literature on the use of EPXMA in conjunction with (heavy metal) pollution studies.

Metal-accumulating compartments are usually granules or vacuoles of 6 main types (i) extracellular, soluble and fairly pure calcium carbonate granules; (ii) insoluble, calcium and phosphorus-rich granules, of ten containing several metal contaminants; (iii) multifunctional, calcium and phosphorus granules containing a high proportion of rather complex organic molecules; (iv) copper-(and sulphur) rich granules; (v) iron-(and phosphorus) rich granules; (vi) Cd, Zn, Cu and Hg -containing vacuoles, where the metals are presumably complexed with cysteine-rich metallothionein proteins, or their derivatives. With a few exceptions, types …

In Situ Hybridization At The Electron Microscope Level, Maximilian Binder

Scanning Microscopy

This tutorial paper will review radioactive and non-radioactive in situ hybridization (ISH) techniques at the electron microscope (EM) level; describe our efforts in comparison to those of other groups who recently have published in this field and discuss some potential future applications. Our contribution is the development of a non-radioactive, postembedding technique for the detection of transcripts on thin sections of Lowicryl K4M-embedded cells or tissues. Biotinylated probes were prepared by nick-translation. Signal detection was accomplished with anti-biotin antibody and protein A-gold complexes. Specific labeling was obtained over structures known to be the site of expression. Compared to EM autoradiography …

Replica-Immunogold Technique Applied To Studies On Measles Virus Morphogenesis, W. Bohn, K. Mannweiler, H. Hohenberg, G. Rutter

Scanning Microscopy

The replica technique was applied to studies on the dynamic process of measles virus budding on infected HeLa cells. Virus structures were identified by labeling with anti-measles antibodies and protein A-gold. The combination of these two methods enabled us (1) to characterize the sequence of virus budding at the plasma membrane, (2) to localize virus structures on cytoskeletons of infected cells, and (3) to study the influence of Ca²⁺ ions on virus structures at the plasma membrane. Studies on platinum carbon surface replicas suggest that the process of virus budding is similar to the genesis of cellular microvilli. Replicas …

Low Load Vickers Hardness Measurements Of Nonconducting Materials In A Scanning Electron Microscope, H. Bangert, X. Cai, A. Wagendristel, A. Kaminitschek

Scanning Microscopy

Vickers hardness tests on microscopic small bodies, e.g., fibers, powder particles, thin layers, etc., require imprint dimensions near or even below the resolution limits of light microscopes. Hence, to detect and evaluate these miniature imprints a scanning electron microscope (SEM) has to be used. For such observations in a SEM, nonconducting samples have to be coated with a thin conductive layer. The influence of these films on the imprint size and thus on the hardness value can be rather significant. On the basis of a systematic investigation in the case of a layer much softer than the sample to be …

Nature And Properties Of Cardiovascular Deposits, B. B. Tomazic, E. S. Etz, W. E. Brown

Scanning Microscopy

Mineral deposits from human aortas and bioprosthetic devices implanted in experimental animals show close similarities in chemical composition, solubility and structural characteristics. Chemical analyses show compositions corresponding to a Na, Mg, CO₃ substituted apatitic calcium phosphate. Synergistic XRO, FT-IR and Raman Mi crop robe spectroscopic data provided coherent indication of Type-B CO₃^2- incorporation. Microscopic and electron microprobe microanalyses, however, indicate substantial morphological and spatial heterogeneity in the deposits.

Solubility and kinetic dissolution data of the mineral fraction of deposits can be compared with the corresponding data of octacalcium phosphate (OCP). This may indicate that OCP is a …

A Proposal For A High Resolution Scanning Ion Microprobe Based On Laser Non-Resonant Post-Ionization Of Sputtered Atoms, Y. L. Wang, R. Levi-Setti, J. Chabala

Scanning Microscopy

A new high resolution scanning ion microprobe (SIM) is described which combines laser non-resonant multiphoton ionization (MPI) and time of flight (ToF) spectroscopy. The proposed instrument is designed to overcome limitations of the conventional secondary ion mass spectrometry (SIMS) method. A pulsed ion probe (with current 1 - 100 pA) is extracted from a liquid metal ion source (LMIS). This beam is purified by a Wien filter, focused to a spot (15 - 150 nm), and scanned across a sample in a raster pattern (512 x 512 pixels). A high power (200 mJ, 193 nm, 500 Hz) ArF pulsed laser …

Interaction Between X-Irradiated Plateau-Phase Bone Marrow Stromal Cell Lines And Co-Cultivated Factor-Dependent Cell Lines Leading To Leukemogenesis In Vitro, E. Naparstek, P. Ankleasria, T. J. Fitzgerald, M. A. Sakakeeny, J. S. Greenberger

Scanning Microscopy

Plateau-phase mouse clonal bone marrow stromal cell lines D2XRII and C3H c1 II produce decreasing levels of M-CSF (CSF-I), a specific macrophage progenitor cell humoral regulator, following x-irradiation in vitro. The decrease did not go below 40% of control levels, even after irradiation doses of 50,000 rad (500 Gy). In contrast, a distinct humoral regulator stimulating growth of GM-CSF/IL-3 factor-dependent (FD) hematopoietic progenitor cell lines was detected following radiation to doses above 2,000 rad. This humoral factor was not detectable in conditioned medium from irradiated cells, weakly detected using factor-dependent target cell populations in agar overlay, and was prominently detected …

Scanning Electron Microscopy Of Microcorrosion Casts: Applications In Ophthalmologic Research, Peter C. Burger, David B. Chandler, Andrzeji W. Fryczkowski, Gordon K. Klintworth

Scanning Microscopy

In light of the complicated nature of the ocular vasculature, it has been difficult to define the normal ocular anatomy by reference to two-dimensional tissue sections. Since it provides three-dimensional replicas, scanning electron microscopy (SEM) of vascular corrosion casts has therefore been an invaluable addition to the study of ocular vasculature. This technique also often permits identification of a normal vessel's arterial, venous, or capillary nature by its surface features. In addition, this technique is finding increased use in defining anatomical features of human vascular disease and is especially well suited for the study of experimental neovascularization as it relates …

Labeling Of Sweet Taste Binding Sites Using A Colloidal Gold-Labeled Sweet Protein, Thaumatin, Albert I. Farbman, Carolyn K. Ogden-Ogle, Göran Hellekant, Scott R. Simmons, Ralph M. Albrecht, H. Van Der Wel

Scanning Microscopy

Thaumatin, an intensely sweet tasting protein, was bound to colloidal gold and applied to the taste bud-bearing foliate papillae of Rhesus monkeys. Examination of thin sections of taste pores showed that gold particles were bound to merocrine secretions of Type I taste bud cells, to some cell remnants of lysed cells, and, most importantly, to small, membrane bounded blebs of cytoplasm. These blebs are thought to be shed into the pore from the tips of taste bud cell microvilli, particularly those arising from Type II cells. The binding of gold particles to microvillus tips and to the blebs suggest that …

The Ultrastructure Of Membranes In Sympathetic Ganglia, Catarina Andersson Forsman, Lars-Gösta Elfvin

Scanning Microscopy

This review presents some recent observations made on membranes in the mammalian sympathetic ganglia after application of freeze-fracturing and histochemistry. After freeze-fracture clear differences have been found between the neuronal and the satellite cell plasmalemma. The satellite cell plasma membrane exhibits specialized intramembrane particles not found in the neuronal membrane. Freeze-fracture cytochemistry reveals a further difference between the neurons and satellite cells i.e., a higher density of 𝛃-hydroxysterols is present in the satellite cell membrane than in the neuronal membrane.

Histochemical methods to localize 5'-nucleotidase, Ca²⁺-ATPase and Na⁺/K⁺-ATPase in the membranes have been utilized. …

Chiropteran Enamel Structure, K. S. Lester, S. J. Hand

Scanning Microscopy

We have examined sectioned and whole teeth of Hipposideros diadema in order to provide a baseline description of bat enamel at electron microscope level. Intact and worn surfaces of whole teeth from representatives of all superfamilies of the suborder Microchiroptera, representatives of the suborder Megachiroptera, and the Ditjimanka fossil tooth have been surveyed.

Whole chiropteran teeth lend themselves well to non-destructive SEM examination; all except Dobsonia sp. showing evidence of prismatic structure at the outer surface. The majority of prisms in chiropteran enamel are horse-shoe shaped becoming rounded and complete only towards the outer enamel surface. Prism packing is typically …