Biology Commons^™

The Use Of Sonic Frequencies As A Cleaning Agent Of Specimens To Be Observed By Scanning Electron Microscopy, G. Familiari, A. Familiari, G. Macchiarelli, L. J. A. Didio, P. M. Motta

Scanning Microscopy

The presence of mucus and/or cellular debris can obscure the fine morphology of the gastrointestinal or respiratory luminal surface, when observed by scanning electron microscopy. With the intent of obtaining a good cleaning of the mucosal surface without altering the ultrafine morphology of epithelial cells, a new model of sonicator/ultrasonicator is presented.

The instrument is supplied with a control system for wave frequency, amplitude and form, and permits a precise regulation of the wave energy. With this instrument it is possible to produce a "cleaning effect" by using any kind of frequency (either sonic or ultrasonic) and/or amplitude and/or waveform …

Cellular Interactions In Hemopoietic Progenitor Cell Homing: A Review, Cheryl L. Hardy, Jose J. Minguell

Scanning Microscopy

Within the bone marrow microenvironment, dynamic cellular interactions are constantly occurring. These interactions involve hemopoietic stem cells, progenitor cells and maturing cells, physically interacting with other cells, some of which may function as accessory cells, and others which comprise the stromal elements; hemopoietic cells also interact with non-cellular elements, such as glycoproteins and fibrous proteins of the extracellular matrix (ECM). These interactions serve to regulate normal hemopoiesis by allowing the communication of regulatory information, migration and subsequent homing of stem cells within specific organs, and presentation of hemopoietic growth factors in a biologically relevant fashion. The goal of this review …

Progress In Scanning Electron Microscopy Of Frozen-Hydrated Biological Specimens, René Hermann, Martin Müller

Scanning Microscopy

Modem scanning electron microscopy yields structural information down to 2 to 5 nm from thin, beam transparent biological specimens. This paper examines the possibilities of garnering this level of structural information from bulk, frozen-hydrated samples.

Freeze-fractured, frozen-hydrated yeast cells, frequently taken as a yardstick to monitor progress in low-temperature scanning electron microscopy, have been used to optimize both metal shadowing methods and observation parameters (e.g. accelerating voltage, electron beam irradiation of the specimen).

Uncoated frozen-hydrated yeast cells do not charge electrically at an accelerating voltage of 30 kV. Increasing charging effects are however observed with decreasing accelerating voltages. Very thin …

Scanning Laser Microscopic Surface Profiles Of Human Enamel And Dentin After Brushing With Abrasive Dentifrice In Vitro, Tetsuo Kodaka, Masaru Kuroiwa, Megumi Kobori

Scanning Microscopy

Automatic brushing with and without commercial dentifrice containing calcium hydrogenphosphate as an abrasive, commonly available in Japan, was performed on the tangential ground surfaces of sound enamel and dentin in human young premolar teeth with loading of about 120 g for 10 minutes in vitro. Their brushed surfaces were observed with a scanning electron and a scanning laser microscope. Brushing with abrasive dentifrice caused rough surfaces to appear and the abrasion of the enamel and the dentin was measured to be about 0.1 and 1.5 μm/min in mean depth, respectively. Under brushing with only distilled water, however, the enamel …

Retinol Deficiency And Urinary Stone Disease: Clinical Evidence Is Missing, P. P. Singh, R. Kiran

Scanning Microscopy

Serum retinal levels were studied in : (a) 95, 56 and 43 normal subjects belonging to lower, middle and upper socio-economic groups respectively, (b) 35 adult males suffering from night blindness, (c) 27 subjects with low retinal levels, (d) 8 retinal deficient subjects (e) 17 male infants suffering from overt retinal deficiency, (f) 43 radiologically confirmed stone patients and (g) age and sex matched controls (infants 20; adults 120). The subjects included in groups b to f were clinically and radiologically examined for stone disease. Some inhibitors and promoters of stone disease were estimated in urine in groups b to …

The Tale Of Parathyroid Function In Idiopathic Hypercalciuria, Bernhard Hess, Philippe Jaeger

Scanning Microscopy

At the origin, idiopathic hypercalciuria has been described as a syndrome consisting of normocalcemia, low plasma phosphate levels and abnormally high urinary calcium excretion. The cause of this syndrome was subject to many investigations throughout the years. Two main pathophysiologic hypotheses have been proposed: a) primary intestinal hyperabsorption of calcium, leading to depression of parathyroid hormone (PTH) secretion ("absorptive" hypercalciuria); and b) primary renal tubular leak of calcium which stimulates PTH secretion (secondary hyperparathyroidism). Most of the published studies indicate that intestinal hyperabsorption of calcium with subsequent relative hypoparathyroidism is the primary event causing idiopathic hypercalciuria, and that …

Study Of Surface Modified Poly(Ethylene) Yarns, Samuel H. Cohen, Heidi Schreuder-Gibson, John T. Stapler

Scanning Microscopy

Spectra® fibers and fabrics have been treated to enhance surface friction to determine if ballistic penetration resistance of Spectra fabric can be increased with improved interfiber friction. Scanning electron microscopy (SEM) has shown the extent of surface modification for plasma treated Spectra yarns and the uniformity of coverage for dip-coated yarns and fabrics. Of particular interest is the observation by SEM that plasma gases etch the surface of the polyethylene, producing varying effects on the fiber surface friction. While difficult to measure spectroscopically, the presence of coatings that affect fiber friction are confirmed by SEM.

Strontium, A Tracer To Study The Transport Of Calcium In Mineralizing Tissues By Electron Probe Microanalysis, Ernst-Rudolf Krefting, Kai Frentzel, Jörg Teßarek, Hans-Jürgen Höhling

Scanning Microscopy

In growth plate cartilage the mineralization starts extracellularly in the lower hypertrophic zone. The mineral formed is the calcium phosphate apatite. Enough calcium and phosphate must be available at the mineralization front as well as in regions with proceeding mineralization. There must be a transport of Ca (and phosphate) to these sites.

Electron probe X-ray microanalysis is a well established method to analyze element concentrations in small volumes, but it cannot discriminate isotopes. Strontium is similar to Ca in its chemical and biological behaviour and is therefore a suitable tracer to investigate the transport of Ca.

Small amounts of Sr …

Strained And Relaxed Semiconducting Silicide Layers Heteroepitaxially Grown On Silicon, J. Chevrier, Le Thanh Vinh, J. Derrien

Scanning Microscopy

The semiconducting silicide ß-FeSi₂, which can be grown epitaxially on silicon, is potentially an interesting material for integrated optoelectronic devices. Its semiconducting state stabilised by a solid state Jahn Teller effect is very unusual. Indeed the epitaxial growth of FeSi₂ on silicon (111) in a Molecular Beam Epitaxy (MBE) chamber has revealed the existence of a metallic strained FeSi₂ phase which is the result of a simultaneous electronic and structural transition. The stability and the relaxation of this strained phase which is specifically due to the epitaxy of FeSi₂ on the silicon (111) face …

Effects Of Citrate On The Different Phases Of Calcium Oxalate Crystallization, H. -G. Tiselius, C. Berg, A. -M. Fornander, M. -A. Nilsson

Scanning Microscopy

Urinary citrate appears to be an important factor in the crystallization process of calcium oxalate and calcium phosphate. The urinary excretion of citrate was found to be significantly lower in patients with calcium oxalate stone disease as compared with normal subjects, and about 30 per cent of the calcium stone formers can be considered as hypocitraturic. The lowest excretion of citrate was recorded in urine collected during the night. Citrate has significant effects on supersaturation with respect to both calcium oxalate and calcium phosphate, it also inhibits the growth of these crystals. In addition, citrate appears to be capable of …

Review: Morphological Changes Associated With Endolymphatic Hydrops, K. C. Horner

Scanning Microscopy

Endolymphatic hydrops of the inner ear is identified as a swelling of the endolymphatic spaces. This morphopathology in man can only be confirmed at postmortem examination although it is believed to underlie the auditory dysfunction and vestibular disturbances associated with Menière's disease. This is an illusive inner ear disorder characterized typically by the fluctuant hearing loss, tinnitus and episodes of vertigo. Menière's disease remains a major problem in otorhinolaryngology since the cause of the disease is not known and various treatments are recommended, often with unsatisfactory results. Experimentally induced endolymphatic hydrops in the animal model has been developed in order …

Mercox®-Methylmethacrylic Acid Mixture Penetrates Into Cells. A Scanning And Transmission Electron Microscopic Study, S. Aharinejad, P. Böck

Scanning Microscopy

During preparation of vascular casts using mixtures of Mercox® and methylmethacrylic acid for scanning electron microscopy, occasionally irregular structures were observed adhering to otherwise well prepared corrosion casts. These artifacts were further analyzed in sections of cast preparations. The bizarre-shaped structures varied in size and were often tightly connected to vascular casts; they withstood KOH maceration and cleaning with formic acid. The persistence of biological material, connective tissue fibers and cells or cellular fragments, became obvious in ultrathin sections. Transmission electron microscopy also showed inhomogeneity of the polymerized casting medium (Mercox®-methylmetbacrylate mixture; v/v: 4:1). An unidentified com-pound of this resin …

Time-Resolved Scanning Electron Microscopy Analysis Of Nanodynamical Structures, J. Jason Yao, Noel C. Macdonald

Scanning Microscopy

We have developed and characterized a time-resolved scanning electron microscopy (SEM) operational mode which provides non-destructive mechanical characterization of nanodynamical structures with 8-bit image resolution and 200 ns time resolution. This time-resolved SEM scheme does not require blanking plates, nor does it require any hardware modification to a commercially available scanning electron microscope. Both time-resolved images and line scan profiles of nanofabricated single crystal silicon tweezers are obtained. This time-resolved SEM operational mode can be used to evaluate a number of important mechanical properties of nanodynamical structures, including time response and resonance mode-shapes.

Renal Stone Formation In Patients With Inflammatory Bowel Disease, R. Caudarella, E. Rizzoli, L. Pironi, N. Malavolta, G. Martelli, G. Poggioli, G. Gozzetti, M. Miglioli

Scanning Microscopy

Kidney stones are more common in patients with inflammatory bowel disease (IBD) than in the general population. The main lithogenetic risk factors were evaluated in patients affected by Crohn's disease and ulcerative colitis. Our results show the presence of several factors, besides hyperoxaluria, in patients with IBD although their behaviour appears different in Crohn's disease and ulcerative colitis at pre- and post-operative stages. Before surgery in patients with Crohn's disease we found a decreased citrate (p < 0.001) and magnesium (p < 0.005) excretion together with a low urinary volume (p < 0.001) and pH (p < 0.005). After surgery patients with Crohn's disease showed a further reduction of magnesium and citrate. Patients with ulcerative colitis before surgery showed a reduced citrate excretion (p < 0.05) and a more acidic pH (p < 0.05) than healthy subjects. Surgical treatment of proctocolectomy with ileal pouch-anal anastomosis seems to increase the risk of stone formation; in fact, after surgery we observed a relevant decrease of urinary volume (p < 0.001), pH (p < 0.0001) and urinary excretion of citrate (p <0.0001) as well as magnesium (p < 0.005). Patients with IBD seem to be at greater risk of stone formation than patients with idiopathic calcium lithiasis; in fact, they show a lower excretion of citrate (p < 0.001) and magnesium (p < 0.001) together with a low urinary pH (p < 0.001) and volume (p < 0.001). Urinary volume reduction is probably one of the major risk factors together with the decrease of small molecular weight inhibitors that is a constant finding in all patients with IBD.

Evaluation And Management Of Dietary Habits In Japanese Renal Stone Formers, Haruo Ito, Tadashi Kotake, Naoto Miura

Scanning Microscopy

To elucidate the relationship between the formation of kidney stones and diet, we carried out a dietary investigation in patients with urinary tract stones. Dietary intakes were estimated for 36 patients (24 men, 12 women) with calcium stones, and compared with the official dietary requirements for the Japanese.

Total protein intake, animal protein intake and animal protein ratio were significantly higher for patients with stones in both men and women. Dietary salt intake was significantly higher for male patients and the total group. Dietary calcium and carbohydrate intakes were significantly lower for patients with stones in men and the total …

Renal Tubular Hypouricemia And Calcium Urolithiasis, Tadashi Kotake, Naoto Miura, Haruo Ito

Scanning Microscopy

The information concerning the relationship of hypouricemia with urinary tract stones is limited. We investigated the incidence and types of hypouricemia, and also studied its relationship to urinary tract stones. Hypouricemia was detected in 3 out of 1520 outpatients (0.20%). The loading tests using pyrazinamide, probenecid and benzbromarone showed that uric acid absorption was impaired before tubular secretion in two cases and incomplete postsecretory reabsorption in one case. Complication of urinary tract stone was found in two cases. The composition of the stones was mixed calcium oxalate and uric acid. Hypouricemia should be recognized as one of the causes of …

Microanalysis Of Individual Silver Halide Microcrystals, Shijian Wu, A. Van Daele, W. Jacob, R. Gijbels, A. Verbeeck, R. De Keyzer

Scanning Microscopy

Elemental distributions and contents of tabular and cubic silver halide microcrystals were analyzed by backscattered electron imaging, scanning transmission electron imaging, X-ray mapping and X-ray analysis in the spot mode by scanning transmission electron microscopy (STEM) combined with energy-dispersive X-ray spectrometry (EDXS). By using a liquid nitrogen cryostage, damage to the microcrystals and drift of the sample under electron bombardment were minimized. Monte Carlo simulation shows the electron trajectories in the silver halide microcrystals for different experimental conditions and directs the selection of the beam position for X-ray spot analysis. The backscattered electron images, scanning transmission electron images and X-ray …

Quantitative And Computer Assisted Electron Microscopic And Microprobe Studies In Dermatology, B. Forslind, A. Emilson

Scanning Microscopy

Electron microscopes are not yet routine instruments in modern dermatological pathology even though they have provided detailed data about pathological changes in the skin for more than three decades. At present, dermatopathology is still dominated by light microscopy and especially so since the introduction of immunological techniques such as the use of monoclonal antibodies. These tools applied at electron microscopic resolution, however, may provide the ultimate identification of cells and subcellular components. In addition, electron microscopes have no peers in areas of quantitative investigation at subcellular levels, e.g. morphometry.

The electron microprobe provides a unique tool in elemental analysis and …

Ultrastructural Effects Of Therapeutic Irradiation On Human Epithelial Tumors, P. Kellokumpu-Lehtinen

Scanning Microscopy

Irradiation induces several cellular changes leading to death of cancer cells and normal cells which is followed by repairing processes of normal cells. We have studied the effects of therapeutic irradiation on head and neck cancers. Tissue samples taken before and during the radical irradiation (50-80 Gy) of the squamous cell carcinomas of the head and neck region were examined by light and electron microscopy. Nuclear atypia was most pronounced cellular change during irradiation. The tumor invasion pattern remained unchanged but the number of mitoses decreased. Lymphocytic infiltration increased at the beginning of the therapy (from 10 to 30 Gy) …

Importance Of Mild Hyperoxaluria In The Pathogenesis Of Urolithiasis - New Evidence From Studies In The Arabian Peninsula, W. G. Robertson, H. Hughes

Scanning Microscopy

The hypothesis that mild hyperoxaluria is more important than hypercalciuria in the pathogenesis of urolithiasis is re-examined in the light of new evidence. Small increments in urinary oxalate in the normal to high-normal range are much more critical than similar rises in urinary calcium for increasing the relative supersaturation of urine with respect to calcium oxalate, the oxalate/calcium ratio in urine, the total volume of calcium oxalate crystals excreted, the proportion of abnormally large crystals and aggregates of calcium oxalate and the severity of the disorder as defined by the recurrence rate of stone-formation. Data from the Arabian Peninsula, where …

Atomic Force Microscopy Of Dna On Mica And Chemically Modified Mica, T. Thundat, D. P. Allison, R. J. Warmack, G. M. Brown, K. B. Jacobson, J. J. Schrick, T. L. Ferrell

Scanning Microscopy

Atomic force microscopy (AFM) was used to image circular DNA adsorbed on freshly cleaved mica and mica chemically modified with Mg(II), Co(II), La(III), and Zr(IV). Images obtained on unmodified mica show coiling of DNA due to forces involved during the drying process. The coiling or super twisting appeared to be right handed and the extent of super twisting could be controlled by the drying conditions. Images of DNA observed on chemically modified surfaces show isolated open circular DNA that is free from super twisting, presumably due to strong binding of DNA on chemically modified surfaces.

Calibration Of Atomic Force Microscope Tips Using Biomolecules, T. Thundat, X.-Y. Zheng, S. L. Sharp, D. P. Allison, R. J. Warmack, D. C. Joy, T. L. Ferrell

Scanning Microscopy

Atomic force microscope (AFM) images of surfaces and samples mounted on substrates are subject to artifacts such as broadening of structures and ghost images of tips due to the finite size and shape of the contacting probe. Therefore, knowledge of the radius of the AFM probe tip is essential for the interpretation of images. We have deduced the shape of the AFM tip by imaging cylindrical biological molecules of various diameters such as deoxyribonucleic acid (DNA), tobacco mosaic virus (TMV), tobacco etch virus (TEV) and bacteriophage M-13 (M-13). Using a paraboloidal tip model and numerically solving equations of contact, the …

Effect Of Chronic Treatment With Diuretics On Mouse Liver: A Morphological And Microanalytical Investigation, Ann-Christin Mork, Anne Von Euler, Godfried M. Roomans

Scanning Microscopy

In an attempt to produce an animal model for the disease cystic fibrosis (CF), mice were treated chronically with the diuretics amiloride and furosemide, in order to cause chronic inhibition of transepithelial ion transport. Experiments were carried out on adult mice (2 months treatment); in addition, pregnant mice were treated with diuretics, and tissue from offspring 2 and 7 days post partum was investigated. Since biliary cirrhosis is a common occurrence in CF, hepatocytes in the treated mice were investigated by X-ray microanalysis and by light and electron microscopy.

Treatment with amiloride caused a significant decrease in cellular Na concentration …

Charge Dynamics At The Silicon(001) Surface Studied By Scanning Tunneling Microscopy And Surface Photovoltage, David G. Cahill, R. J. Hamers

Scanning Microscopy

Scanning tunneling microscopy measurements of local surface photovoltage of the Si(001) surface reveal the existence of local charging produced by the tunneling current. Since the tunneling current is confined to a region of near atomic dimensions, charge transport between surface and bulk electronic states is probed with high spatial resolution. The surface charge is enhanced while tunneling at the bonded, type-B atomic step and at specific point defects demonstrating atomic-scale variations in the charge dynamics.

The Spatial Distribution Of Backscattered Electrons Revisited With A New Monte Carlo Simulation, Kenji Murata, Masaaki Yasuda, Hiroaki Kawata

Scanning Microscopy

A Monte Carlo simulation program including the discrete energy loss process has been developed, based on the Mott cross section for elastic scattering and the Vriens cross section for inelastic scattering. A deficiency of the previous model which is based on the screened Rutherford cross section and the Bethe law is made clear, from comparison between the new and old results such as the energy distribution of backscattered electrons for a Cu target. With the new Monte Carlo model, the radial spreading and penetration depth of both all and low-loss backscattered electrons have been studied for the Cu target at …

Dentinogenesis And The Calciotraumatic Response To The Injection Of Lead Or Fluoride Ions, John Appleton

Scanning Microscopy

A number of ions can disturb the formation of dentine resulting in a calciotraumatic response. The calciotraumatic response following the injection of sodium fluoride was investigated using backscattered electron imaging in the scanning electron microscope and compared with the response to lead acetate. With fluoride, there was formation of a hypermineralized band succeeded by a relatively hypomineralized band, but with lead acetate, only a hypomineralized band was produced. However, there were some differences in the response between the labial and lingual dentine with both ions. In the labial dentine following injection of sodium fluoride, the onset of hypermineralization was less …

Scanning Electron Microscope Observations Of Brine Shrimp Larvae From Space Shuttle Experiments, Lynnette Debell, Avelina Paulsen, Brian Spooner

Scanning Microscopy

Brine shrimp are encysted as gastrula stage embryos, and may remain dehydrated and encysted for years without compromising their viability. This aspect of brine shrimp biology is desirable for studying development of animals during space shuttle flight, as cysts placed aboard a spacecraft may be rehydrated at the convenience of an astronaut, guaranteeing that subsequent brine shrimp development occurs only on orbit and not on the pad during launch delays.

Brine shrimp cysts placed in 5 ml syringes were rehydrated with salt water and hatched during a 9 day space shuttle mission. Subsequent larvae developed to the 8th larval stage …

Scanning Electron Microscopy Of Intracellular Organelles In The Young Odontoblasts Of Rats, Yasutomo Iwai-Liao, Yoshikage Higashi, Masakazu Ishikawa, Hideaki Hori

Scanning Microscopy

Intracellular structures of the odontoblasts were studied by scanning electron microscopy (SEM) using a modified AODO (aldehyde prefixed-osmium-DMSO-osmium) method. Well-developed flattened and layered rER (rough endoplasmic reticulum), paved with its associated ribosomes on its outer surface, were clearly observed in the odontoblast. Branched tubular mitochondria with nodules and swollen endings, interposing between and passing through the fenestrated layered rER, were demonstrated in the functional cells. Oblique and cross-sections of both the rER system and tubular mitochondria showed orthodox configurations similar to those usually described in transmission electron microscopy (TEM) studies. Many finger-like projections constructing the cristae directing towards the inner …

On The Origin Of Electron-Beam-Induced-Current Contrast Of Extended Defects In Silicon, M. Kittler, W. Seifert

Scanning Microscopy

The paper reviews the origin of bright and dark Electron-Beam-Induced Current (EBIC) contrast due to extended defects in silicon, inclusively a brief discussion of contrast modelling. Particular emphasis is put on the role of impurities demonstrated to determine contrast in many cases (extrinsic contrast origin). The understanding of the prevalent contrast type -dark contrast due to enhanced recombination at defects -is well supported by existing phenomenological contrast models which can, therefore, be used as a basis for contrast interpretation. In the context of extrinsic vs. intrinsic contrast origin, the influence of defect dimensionality on contrast is addressed, indicating that grain …

The Normal, Cryptorchid And Retractile Prepuberal Human Testis: A Comparative Morphometric Ultrastructural Study Of 101 Cases, Saverio Cinti, Giorgio Barbatelli, Claudia Pierleoni, Manlio Caucci

Scanning Microscopy

Fifty-two surgical biopsies from retractile testes of patients in pediatric age (3-14 years), of which 25 were treated with hormonal therapy (RT) and 27 did not undergo therapy before orchidopexy (RNT), were compared with the biopsies of 19 normal (N) and 30 cryptorchid or ectopic (E) testes. A light and electron microscopic morphologic and morphometric study was performed. For the quantitative investigation 4 parameters were selected: a) the mean tubular diameter (on 20 cross-sections); b) the mean spermatogonial number per tubular section; c) the mean nucleolar area of the Sertoli cells; and d) the mean thickness …