Biology Commons^™

The Effects Of Diethyldithiocarbamate (Ddc) On The Astrocytic Cytoskeleton, Mary F. Mcmanus, Louis D. Trombetta

Scanning Microscopy

The dithiocarbamates are a group of compounds that are used extensively in industry, agriculture and medicine. Exposure to these compounds has caused deleterious effects to both the central and peripheral nervous systems. Cultured rat hippocampal astroglia treated with 35 μg/ml diethyldithiocarbamate (DDC) in media were studied for alterations to the cytoskeleton. Examination by both immunohistochemistry and scanning electron microscopy revealed disruption of the cytoskeletal elements. This occurred in a progressive time-dependent manner. Electrophoretic patterns demonstrated two cytoskeletal protein alterations. The microtubular protein, β-tubulin, appeared to have an altered mobility while the major intermediate filament protein, glial fibrillary acidic protein (GF …

Gold, Electron Microscopy, And Cancer Therapy, James F. Hainfeld

Scanning Microscopy

Radioactive gold has properties suitable for radiotherapy and can provide lethal irradiation to cells. If the gold is conjugated to a targeting molecule, such as an antibody, it may be possible to specifically deliver the dose to tumor cells. Various gold particles are possible candidates and include gold colloids with adsorption of antibodies or gold clusters with covalent attachment. Different sizes of gold particles are available and some may be preferred for certain situations. Problems with intravenous injection and in vivo delivery are numerous, and a more tractable application is the direct instillation into the urinary bladder of radiogold immunoconjugates …

Swift Heavy Ion Induced Electron Emission From Solids, Hermann Rothard

Scanning Microscopy

Quite a number of experiments have been performed on electron emission from solids induced by slow (projectile velocity Vp < 1 atomic unit) or medium velocity heavy ions (projectile energy Ep < 1 MeV/u). Only a few experiments have been made with fast heavy ions (projectile atomic number Zp > 8, Ep > 2 MeV/u) concerning either electron emission yields -y, or double differential electron energy spectra d2n(0)/dEd0 as a function of the observation angle 0. We present the results obtained so far on electron emission induced by fast (Ep > 2 MeV/u) heavy ions (Zp ~ 6). Topics discussed include experimental results for electron yields, -energy and -angular distributions and channelling phenomena as well as the theoretical approaches. We also present new results from recent studies on the evolution of electron yields …

Semiquantitative Analysis By Scanning Electron Microscopy Of Cochlear Hair Cell Damage By Ototoxic Drugs, Takehisa Saito, Yasuhiro Manabe, Noriyuki Honda, Takechiyo Yamada, Takehito Yamamoto, Hitoshi Saito

Scanning Microscopy

The ototoxicity of cisplatin and carboplatin in the organ of Corti of the guinea pig was evaluated semiquantitatively. Damage of the stereocilia of outer hair cells (OHCs) observed by scanning electron microscopy (SEM) was classified into normal, grade 1 (10-50% loss of stereocilia), grade 2 (less than 50% remaining stereocilia), or grade 3 (missing stereocilia). The OHCs observed by light microscopy (LM) were classified as remaining or missing cells. Fifty OHCs of each row in the middle part of each turn of the cochlea were counted (a total of 150 cells per turn). Guinea pigs were administered 5 mg/kg of …

Comparison Of Cell Sediment And Surface Grown "Test Plaque" Using Scanning Electron Microscopy, S. M. Mccormack, C. M. D. Maran, K. M. Scott-Anne, D. T. Zero

Scanning Microscopy

Scanning electron microscopy was used to compare the morphology, integrity and distribution of bacterial cells in a test plaque grown on the surface of enamel with that of the cell sediment plaque routinely used in a short-term intraoral caries model. Cultures of S. mutans IB-1600 or S. sobrinus 6715-13 were grown in complex media supplemented with either 2.0% sucrose (glucan plaque) or 0.2 % glucose (non-glucan plaque). Cell sediment (CS) plaque was prepared by centrifuging the cultures after incubation, recovering the cell sediment, and spreading it on Metricel membrane filter paper. Surface grown (SG) plaque was prepared by suspending saliva-coated …

Effect Of Sodium Saccharin On The Neonatal Rat Bladder, Samuel M. Cohen, Martin Cano, Margaret K. St. John, Emily M. Garland, Mohamad Khachab, Leon B. Ellwein

Scanning Microscopy

In a two-generation bioassay, high doses of dietary sodium saccharin (NaSac) produce bladder carcinoma in rats, whereas acid saccharin (HSac) does not effect the urothelium. NaSac and HSac administered as 5% of the diet to F0 Sprague-Dawley (SD) and F344 rats, continued through to the weaned male rats for ten additional weeks. Control 3H-thymidine labeling index (LI) was high prior to and at birth (approximately 11%), declining rapidly by weaning (to < 0.2). Neither NaSac nor HSac increased proliferation through 7 days of age. NaSac increased the proliferation rate at later times, whereas HSac did not. The LI decreased to control levels in NaSac-fed rats switched to control diet after weaning and increased in control-fed rats switched to NaSac after birth or weaning. In a second experiment, 5% NaSac did not affect urothelial morphology of SD rats through 7 days. By 21 days post-birth, urothelial hyperplasia occurred in NaSac-fed rat. The LI in treated versus control was similar through gestation, with a slight difference by 7 days. LI was significantly different by 21 days post-birth, but was similar between males and females. These results provide additional evidence for the increased cell proliferative effects of NaSac during the neonatal period, but not during gestation.

Three-Dimensional Configuration Of Crypts Of Different Types Of Colorectal Adenomas, Keijiro Araki, Takuro Ogata

Scanning Microscopy

The three-dimensional configuration of isolated crypts of normal human colonic mucosa and colorectal adenomas was examined by scanning electron microscopy. For isolation of the crypts, the digestion method with HCl was used for formalin fixed tissues, and the separation method with ethylenediaminetetraacetic acid (EDT A) following ultrasonication was applied to fresh tissues. In a comparative study, the NaOH cell-maceration method, which visualized the sub-basal laminal collagen sheath, was applied. The isolated crypts from the normal colon were visualized as a single straight tubule resembling a test tube. Most isolated crypts of the tubular adenomas were visualized as elongated fan-like structures …

Cell Surface Changes Of Hemopoietic Cells During Normal And Leukemic Differentiation: An Immuno-Scanning Electron Microscopy Study, D. Soligo, E. P. De Harven, N. Quirici, L. Caneva, G. Lambertenghi Deliliers

Scanning Microscopy

Hemopoietic cells display a wide range of cell surface antigens which are either lineage specific or acquired during differentiation. Monoclonal antibodies can be used, in conjunction with colloidal gold markers, to identify under the scanning electron microscopy (SEM) at the single cell level, specific lineage or maturation stages in the hemopoietic bone marrow. Normal bone marrow cells, either gradient separated or purified by immuno-magnetic methods and leukemic cell samples, which can be considered as "frozen" stages of hemopoietic differentiation, have been studied with this method. Typical cell surface morphologies, which characterize immature progenitor cells and cells committed or differentiated towards …

Etiology Of Calcium Oxalate Nephrolithiasis In Rats. I. Can This Be A Model For Human Stone Formation?, W. C. De Bruijn, E. R. Boevé, P. R. W. A. Van Run, P. P. M. C. Van Miert, R. De Water, J. C. Romijn, C. F. Verkoelen, L. C. Cao, F. H. Schröder

Scanning Microscopy

Crystal retention is studied in a rat-model system as a possible mechanism for the etiology of human nephrolithiasis. A crystal-inducing diet (CID) of ethylene glycol plus NH₄Cl in their drinking-water is offered to healthy rats to generate intratubular crystals. Subsequently, the fate of retained crystals is investigated by allowing the rats a tissue recovery/crystalluria phase for three, five and ten days, respectively, on normal drinking water.

The process of exotubulosis is observed in cortex and medulla of aldehyde-fixed kidneys after three days recovery. After five days, crystals are predominantly seen there in the interstitium. After ten days, cortex …

Etiology Of Calcium Oxalate Nephrolithiasis In Rats. Ii. The Role Of The Papilla In Stone Formation, W. C. De Bruijn, E. R. Boevé, P. R. W. A. Van Run, P. P. M. C. Van Miert, R. De Water, J. C. Romijn, C. F. Verkoelen, L. C. Cao, J. M. Van 'T Noordende, F. H. Schröder

Scanning Microscopy

In kidneys of healthy rats submitted to a crystal-inducing diet (CID) with ethylene glycol (EG) and NH₄Cl, the fate of retained crystals in the papillar region is studied during a recovery period of one, five or ten days, as model system for human nephrolithiasis. Scanning electron microscopy (SEM) shows, at papillary tips bulging into the calycine space, crystal masses covered either by the epithelium or a thin fibrous veil, or by unidentified mobile cuboidal cells. After CID plus one or five days recovery, small sub-epithelial swellings are seen of large sub-epithelial crystals at or around the papillary tip. …

Notes On The Microstructure Of The Nautilus Shell, P. R. Mitchell, P. P. Phakey

Scanning Microscopy

The shell of the Nautilus was examined using scanning electron microscopy, transmission electron microscopy and polarized light microscopy. The structure consisted of two major layers: a porcellaneous outer layer and a nacreous inner layer. Most of the porcellaneous layer was composed of granular crystals randomly distributed with a substructure suggestive of bundles of acicular crystallites. A separate prismatic sublayer of the porcellaneous material was composed of a more regular arrangement of crystals. The nacre was composed of alternating crystalline lamellae and films of organic material. The lamellae were formed of many polygonal crystal platelets. The growth surface of the nacre …

Investigation Of Nanoparticles In High Resolution Scanning Electron Microscopy (Sem) And Low Voltage Sem By Digital Image-Analysis, B. Ocker, R. Wurster, H. Seiler

Scanning Microscopy

Small particles (Cu, Ag, In, Sn, Au, also MgO and NaCl) were prepared in the diameter range from 1 nm to 100 nm on different conductive substrates by thermal evaporation in high-vacuum or in an inert gas atmosphere. Imaging of the particles was performed in a high resolution scanning electron microscope (HRSEM) that can also be operated at low beam voltages of a few hundred volts. This mode of operation is called low voltage SEM (LVSEM). Scanning electron micrographs were taken at different beam voltages V_O (0.5-30 kV). The micrographs were digitally recorded and analyzed with an image processing …

High Resolution Electron Microscopy Of Enamel Crystallites Demineralized By Initial Dental Caries, Yoshihiko Hayashi

Scanning Microscopy

Acids produced by various oral bacteria cause mineral loss and crystallite dissolution during the development of enamel caries. In order to demonstrate this phenomenon, the initial disappearance of lattice fringes and the formation of a central perforation in crystallites were examined by high resolution electron microscopy (HREM) in initial enamel caries without macroscopic tissue evidence of destruction. Ultrathin sections were also examined by selected area electron diffraction to reveal the mineral phase of the surface layer in carious enamel.

A marked variation in the dissolution pattern was disclosed in the initial carious lesions. HREM revealed that disappearance of the lattice …

Controlling Influence Of Phosphocitrate In Vitro And In Vivo On Calcium Oxalate Crystal Formation And Growth, John D. Sallis, Nathan F. G. Parry, John D. Meehan, Harold Kamperman, Maree E. Anderson

Scanning Microscopy

Calcium oxalate (CaOx) crystallization in the presence of phosphocitrate (PC) was studied by both in vitro and in vivo techniques. Crystals of the monohydrate (COM) and the dihydrate (COD) forms were generated under controlled conditions in a silica gel matrix. Our data indicated only COD crystals formed when PC was present, inferring that the COD to COM transformation was being impeded. COD crystals were smaller in size than controls and there was evidence of interpenetral twinning. An in vivo study using a rat bladder implant model noted similar findings. Scanning electron microscopy (SEM) revealed that implants recovered from PC treated …

Revascularization Of An Excisional Wound In Gingiva And Oral Mucosa. A Scanning Electron Microscopic Study Using Corrosion Casts In Rats, Nils J. Selliseth, Knut A. Selvig

Scanning Microscopy

The purpose of this study was to examine microvascular regeneration associated with gingival wound healing. A full-thickness piece of gingiva and oral mucosa was excised along the palatal aspect of the right maxillary first and second molars in 20 young Wistar rats. The contralateral side served as unoperated control. After 2, 4, 7, 10 or 20 days of healing, microvascular corrosion casts were produced and examined by scanning electron microscopy. At 2 days, vessels surrounding the wound were dilated and impressions representing sites of leukocyte margination were prominent in the walls of venules. Capillary buds were emerging from venules and …

Scanning Electron Microscopy And Transmission Electron Microscopy Aspects Of Synergistic Antitumor Activity Of Vitamin C - Vitamin K3 Combinations Against Human Prostatic Carcinoma Cells, Jacques Gilloteaux, James M. Jamison, Meenaxi Venugopal, David Giammar, Jack L. Summers

Scanning Microscopy

A MTT/formazan assay was used to evaluate the antitumor activity of vitamin C (Vit C), vitamin K₃ (Vit K₃), or vitamin C:vitamin K₃ combinations against a human prostatic carcinoma cell line (DU145). Both Vit C and Vit K₃ alone exhibited antitumor activity, but only at elevated doses. When Vit C and Vit K3 were combined at a C:K₃ ratio of 100:1 and administered to the carcinoma cells, the 50% cytotoxic concentrations (CD50) of the vitamins decreased 10-to 60-fold. Subsequently, the DU145 cells were examined with transmission and scanning electron microscopy (TEM and SEM) following …

Experimental Calcium Oxalate Nephrolithiasis And The Formation Of Human Urinary Stones, Saeed R. Khan

Scanning Microscopy

Calcium oxalate nephrolithiasis in rats requires induction of hyperoxaluria which results in increased urinary calcium oxalate supersaturation. As a result of low to mild chronic hyperoxaluria, calcium oxalate crystals deposit first in the papillary collecting ducts. Crystal deposition in the kidneys is preceded by calcium oxalate crystalluria and starts with the retention of aggregated calcium oxalate crystals in the renal tubules. Retained crystals move from the tubules to the interstitium, and in the process, become anchored to the tubular basement membrane. Crystal aggregates present in the superficial peripheral collecting ducts of the renal papillae ulcerate through to the papillary surface …

Cathodoluminescence Of Rare Earth Doped Zircons. I. Their Possible Use As Reference Materials, F. Cesbron, P. Blanc, D. Ohnenstetter, G. Rémond

Scanning Microscopy

Synthetic zircon crystals (ZrSiO₄), undoped and doped with Y³⁺, La³⁺, Ce³⁺, Pr³⁺, Nd³⁺, Sm³⁺, Eu³⁺, Gd³⁺, Tb³⁺, Dy³⁺, Ho³⁺, Er³⁺, Tm³⁺, Yb³⁺, Lu³⁺, were grown from a flux consisting of a mixture of Li₂MoO₄ and MoO₃ heated to 1125°C and then cooled to 750°C. The cathodoluminescence (CL) spectra of these zircons were analyzed at room-temperature and near liquid nitrogen temperature with a CL spectrometer …

Diamond Luminescence, R. Heiderhoff, L. J. Balk

Scanning Microscopy

Luminescence spectroscopy is an established tool to investigate natural, high pressure synthesized, and chemical vapour deposited (CVD) diamond. The spectral range extends from 5.3 eV in the ultraviolet to approximately 1.2 eV in the near-infrared. More than 100 optical centres have been observed.

Since the early 1930's, semiconducting diamond for electronic devices has been of interest to science. The large bandgap (5.5 eV), low dielectric constant (5.7), and high thermal conductivity (about 5 times larger then that of Ag), as well as the superior charge-carrier transport properties, such as electron and hole mobility (µ^-: 2200 cm²/Vs, …

Temperature-Dependent Cathodoluminescence Spectroscopy And Microscopy As A Tool For Defect Identification In Semiconducting Ceramics: Application To Batio3 Ceramics, T. Hübner, U. Marx, J. Schreiber

Scanning Microscopy

Cathodoluminescence (CL) spectroscopy and microscopy were applied to investigate the characteristic grain-boundary contrast in semiconducting ferroelectric BaTiO₃ ceramics. It was shown, that "chemically clean" grain boundaries do not reveal any specific CL components neither in the visible nor in the infrared part of the spectrum. Instead, the contrast arises from at least two different non-radiative recombination centers present in the grain and the grain-boundary zones, respectively. Activation thresholds for these centers were determined from the temperature dependence of the integral CL signal down to 30K. The different values found explain the contrast reversal observed in BaTiO₃ ceramics upon …

Cathodoluminescence Of Rare Earth Doped Zircons. Ii. Relationship Between The Distribution Of The Doping Elements And The Contrasts Of Images, G. Rémond, P. Blanc, F. Cesbron, D. Ohnenstetter, O. Rouer

Scanning Microscopy

Cathodoluminescence (CL) color photographs using an optical CL microscope with a cold cathode electron gun are compared with non-spectrally resolved (polychromatic) and selected wavelength CL images obtained by means of a scanning electron microscope equipped with a CL spectrometer. It is the aim of this paper to show how the interpretation of the contrasts of CL images depends on the knowledge of the CL photon energy distributions participating to the observed contrasts as well as the matrix effects modifying the number of emitted photons compared to that of generated photons. It is shown that the impurities different from the rare …

Ultrafast Carrier Capture In Quantum Well Structures, P. W. M. Blom, J. E. M. Haverkort, J. Claes, P. J. Van Hall, J. H. Wolter

Scanning Microscopy

We present an experimental and theoretical study of the carrier capture time into a semiconductor quantum well. The carrier capture time was obtained by measuring both the rise of the quantum well (QW) population using time-resolved luminescence measurements and the decay of the barrier population using pump-probe correlation experiments. In the first technique, we compare the QW rise-times after direct (below the barrier band gap) and indirect (above the barrier band gap) excitation in order to eliminate the effects of relaxation and exciton formation in the quantum well.

We report the first experimental observation of oscillations in the carrier capture …

Optical Studies Of Ingaas/Gaas Multiple Quantum Wells (Mqw's) And Gaas/Si Using Novel Scanning Electron Microscopy Based Techniques, D. H. Rich, H. T. Lin, Y. Tang, K. Rammohan, A. Larsson

Scanning Microscopy

The influence of defects on electron-hole plasma transport in nipi-doped in _0.2Ga_0.8As/GaAs multiple quantum wells (MQWs) has been studied using a novel technique called electron beam induced absorption modulation (EBIA) imaging. Modulation doped MQW structures exhibit large optical nonlinearities and are important for the development of all-optical spatial light modulators used in optical computing and communication. The electron-hole plasma is generated by a high-energy electron beam in a scanning electron microscope and is used as a probe to study the MQW absorption modulation induced locally by the electron beam. The influence of structural defects on the …

Time-Resolved Luminescence From Two-Dimensional Electrons In High Magnetic Fields: A Tool For Studying The Fractional Quantum Hall Effect, Rolf J. Haug, Igor V. Kukushkin

Scanning Microscopy

Time-resolved magnetoluminescence investigations of specially doped AlGaAs/GaAs heterostructures allow the study of the electronic properties of two-dimensional electrons. The interactions of the two-dimensional electrons lead in high magnetic fields to the fractional quantum Hall effect. By analyzing the mean energy of the recombination line observed in the luminescence spectrum, the electronic properties of the fractional quantized states can be deduced. For negligible interaction between the charged acceptors and the interacting electron system, the derivative of the mean energy versus filling factor allows to obtain the jump of the chemical potential in crossing a fractional filling factor. From these jumps, the …

Luminescence From Semiconductor Quantum Wires, Quantum Dots, And Monolayer Quantum Wells: Bottleneck And Localization Issues, C. M. Sotomayor Torres, P. D. Wang, N. N. Ledentsov, Y. -S. Tang, H. Qiang, F. H. Pollak, H. F. Ghaemi, B. B. Goldberg

Scanning Microscopy

Semiconductors nanostructures are fabricated using a range of techniques which inevitably have an impact in the resulting optical properties. Multilayers are grown by epitaxial techniques with a varying degree of uniformity in thickness, composition, etc., all leading to localisation effects in two-dimension. These multilayers are patterned to fabricate wires and dots using, in this case, electron beam lithography and dry etching. The fabrication steps contribute to modifications of the optical properties, beyond the expected purely confinement-related effects.

An overview of linear and modulation spectroscopy is presented to demonstrate the impact of fabrication steps as well as of lateral confinement upon …

Surface Recombination Velocity And Bulk Carrier Lifetime Measurement Of Silicon Crystals By Using Photoluminescence Time Decay, Karsten Thölmann, Masakazu Yamaguchi, Akihiro Yahata

Scanning Microscopy

The time decay for photoluminescence (PL) emitted from silicon crystals has been used to obtain both bulk carrier lifetime (Tb) and surface recombination velocity (S). Experimental results were interpreted with the assumptions that the sample was under a low-excitation condition and that the ratio of radiative to non-radiative recombination rates was constant throughout the carrier decay process. Analysis was applied to several wafers covered with different kinds of silicon dioxide (SiO₂). The results indicate that PL time decay measurement is effective to obtain the values of Tb and S.

Interpretation Of Cathodoluminescence Spectra Obtained From Dolomite And Calcite Gangue Minerals, And Dolostone Breccias In The Central Tennessee Zinc District (U.S.A.), Otto C. Kopp, E. Loren Fuller Jr., Michael R. Owen

Scanning Microscopy

Spectral patterns were obtained for zoned dolomite and unzoned calcite gangue, and dolostone breccia fragments from the Right Fork area in the central Tennessee zinc district (U.S.A.). The samples had been analyzed previously for Fe, Mn, and other trace elements using a synchrotron XRF probe. Spectra were obtained for zoned dolomite, breccia fragments, and unzoned calcite using an ELM2-B cold-cathode Luminoscope attached to an Oriel Multispec Compact Spectrograph. Spectra obtained for the prominent dolomite zones, which luminesce medium-bright to bright red to the eye, revealed a broad peak in the vicinity of 460 nm and a more intense peak in …

Three-Dimensional Thermoluminescence Spectra And Their Application In The Study Of Some Sedimentary Quartz, J. R. Prescott, R. B. Scholefield, A. D. Franklin

Scanning Microscopy

The intensity of thermoluminescence emission is a function of both temperature and photon energy (or wavelength) and therefore lends itself to a three-dimensional (3-D) display, either in the form of an isometric plot or a contour diagram. The technique of 3-D thermoluminescence spectrometry is briefly reviewed and the advantages and applications are illustrated by reference to the spectral properties of samples of Australian sedimentary quartz drawn from the context of thermoluminescence dating. In this context, the temperature of emission, the photon energy and the ease with which the emission is bleachable by sunlight are of significance. It is suggested that, …

Cathodoluminescent Properties Of Single Crystal Materials For Electron Microscopy, Rudolf Autrata, Petr Schauer

Scanning Microscopy

The results of measurements of cathodoluminescence efficiencies, decay characteristics and emission spectra of YAG:Ce, YAP:Ce, P47 (Y₂SiO₅:Ce) and CaF₂:Eu single crystals at excitation by electrons with an energy of 10 keV and a current density of the order of 10^-8 A cm^-2 are presented. Advantages and disadvantages of the individual single crystals intended for application in electron microscopes are dealt with. Attention is paid to the photomultiplier tube (PMT) matching, degradation and afterglow of the mentioned single crystals. For YAG:Ce, the effect of the activator concentration of crystals and the effect of …

Can Photo- And Cathodoluminescence Be Regarded As Complementary Techniques?, S. Myhajlenko, R. A. Puechner, J. L. Edwards, D. B. Davito

Scanning Microscopy

Photoluminescence (PL) usually provides macroscopic, high quality spectroscopic data. Cathodoluminescence (CL), on the other hand, offers the same information with microscopic imaging. However, replicating PL signatures in a CL system is not straightforward since matching experimental conditions, such as temperature and excitation density, is difficult. The matter is further exacerbated by inherent differences in the nature of excitation: electrons versus photons. Our work with high purity semiconductors suggests that CL is generally more sensitive to excitation "circumstance" than PL. For example, electrons can cause sample charging and contamination-related phenomena that dramatically affect CL. Changes in surface attributes (e.g., by chemical …