SEARCH · PubMed Health

Results for “Microscopy, Electron, Scanning”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,045 records · Page 58Linked to original sources

PubMedDate not supplied

"Killer"-type phenomena in the immune pathology of some chronic internal diseases. (Scanning electron microscopy studies).

Aspects of cytotoxicity followed by cytolysis have been described by many authors in neoplasias. Using scanning electron microscopy, the authors have investigated the cellular population from 179 patients with various chronic internal diseases such as: chronic hepatitis, diabetes mellitus, systemic lupus erythematosus, scleroderma, chronic lymphocytic leukemia. In some of the forms of disease with severe clinical and biological phenomena, they have detected the presence of "killer" type phenomena, having as target cells either the monocytomacrophage or the T or B lymphocytes. Iconographic aspects are demonstrating the presence of this phenomenon, observed particularly in the peripheral blood. Detection of such phenomena is assumed to provide information on prognosis of the chronic disease investigated and on the effects of therapy at cellular level.

Cytotoxicity, Immunologic↗

PubMed1978

Surface features of Sézary cells. A scanning electron microscopy study.

The surface features of circulating cells from three patients with Sézary syndrome were examined by scanning electron microscopy. The Sézary cells were mostly spherical and displayed varying numbers of microvilli. Most cells had moderately to markedly villous surfaces and had surface features similar to circulating leukemic lymphocytes isolated from patients with chronic lymphocytic leukemia. Some cells were more irregular in shape, while others displayed clusters of polarized microvilli and small uropods. Similar findings were seen in thin sections of cells on transmission electron microscopy.

Humans↗

PubMed1978

Identification of epithelial cells and fibroblasts in hypophysis intermediate lobe cultures by scanning electron microscopy.

Cell cultures of the rat pituitary intermediate lobe grown for eight days were studied in the scanning electron microscope. The epithelial cells and fibroblasts could be differentiated by the characteristic structures of the cell surface and the cell association features, The epithelial cells were characterized by blebs and rugae, microvilli, and occasionally by some cilia. The surface of the fibroblasts was smooth or bore microvilli. Scanning electron microscopy may provide special information for the characterization of endocrine cell cultures.

Animals↗

PubMedDate not supplied

Morphology and growth cycle of Mycoplasma meleagridis viewed by scanning-electron microscopy.

The three-dimensional structure of Mycoplasma meleagridis strain RY-39A was studied by scanning-electron microscopy. The morphologic forms observed between 12 hours and 7 days suggest that the organism undergoes a sequential metamorphosis in its development. Single rounded forms in lag phase give rise to larger cells and filaments in the log phase, which fragment into coccus forms in the late stationary phase.

Microscopy, Electron, Scanning↗

PubMed1998

Scanning electron microscopy of the egg surface of the common toad, Bufo bufo, following fertilization and during first cleavage.

Scanning electron microscopy was applied for surface analysis of unfertilized and fertilized eggs of the common toad, Bufo bufo. In unfertilized eggs two types of surface protrusions were found: microvilli and microfolds. 5 min post fertilization (pf), at the place of sperm entrance, a fertilization body appears, surrounded by a group of small depressions, which gradually spread over the whole egg surface. This phenomenon is considered to reflect structural changes of the egg membrane, occurring in response to cortical granule breakdown. Another process which follows fertilization is the disappearance of microfolds and the formation of microvilli. Shortly before the first cleavage, the egg surface smooths out and a zone of spherical microvilli becomes visible at the presumptive furrow region. While the cleavage furrow penetrates into the egg, microvilli appear at the surface of the newly forming blastomeres.

Animals↗

PubMed1998

Scanning electron microscopy of the root surface texture of extracted periodontally diseased teeth following various etching and chelating regimens.

Scanning electron microscopy of root surfaces that had been ultrasonically scaled and subjected to various conditioning regimens revealed the presence of two distinct types of cracks: extensive cracks, presumed to have been caused by drying before and during sputter-coating procedures; and smaller cracks that reflected the pattern of the irregular underlying dentin. Both etching and chelating agents appear to cause demineralization of the interfacial layer between cementum and dentin, causing a "peeling off" of cementum and exposure of the underlying dentin. The results suggest that burnishing the scaled root surface with either saline or any of the etching or chelating agents for at least 10 seconds, followed by soaking the cementum in 8% ethylenediaminetetraacetic acid for about 40 seconds, achieved a root surface that might be regarded as optimal for regeneration of periodontal tissues.

Acid Etching, Dental↗

PubMed1995

Conjunctival tissue examination in severe eye burns: a study with scanning electron microscopy and energy-dispersive X-ray analysis.

BACKGROUND: Long-lasting inflammation is a major problem in treatment after severe eye burns and may find expression in an altered elemental composition of the conjunctiva. Particulate contamination of biological tissue induces such inflammatory processes. In the anterior eye segment, trauma or subsequent therapy may give rise to such contamination. Scanning electron microscopy and energy-dispersive X-ray analysis are able to detect traumatic residues of submicron size and changes of the elemental composition. METHODS: Conjunctival specimens from first-time peridectomy of three healthy and nine severely burnt-eyes were examined with scanning electron microscopy and energy-dispersive X-ray analysis. The samples were prepared as cryo- or paraffin sections, mounted on carbon blocks and coated with evaporated elemental carbon. RESULTS: The samples of healthy conjunctiva showed higher concentrations of Na, P and CI. These elements showed lower concentrations in conjunctival stroma of burnt eyes excised before the 20th day after trauma than in material obtained subsequently. In two burnt conjunctival specimens there was severe traumatic contamination with Ca in Ca(OH)2 and CaO burns, and in one case the traumatic substance was Si, in a peroxide plus silicone spray burn. In the remaining six cases, particulate contamination with Fe, Al, Ni, Zn, Cu, Ti and other substances was present in the burnt conjunctivas, while no contamination was detected in the specimens of healthy conjunctivas. CONCLUSIONS: The origin of the contaminant particles is assumed to be the trauma itself and the subsequent therapy. These investigations stress the importance, for clinical purposes, or early peridectomy and contamination-free therapy.

Burns, Chemical↗

PubMed1987

Scanning electron microscopy of black stain on human permanent teeth.

Black stain may develop on the coronal surfaces of human teeth, and this type of stain is common in the Hong Kong Chinese population. The present study was undertaken to ascertain if the deposit conforms in composition to the black stain found elsewhere, and to describe its ultrastructure using the scanning electron microscope. Gram-stained smears were made from black stain on the teeth of 11 adult Hong Kong Chinese and studied microscopically. From another 15 persons extracted teeth exhibiting black stain were obtained and fixed. Two ground sections were made from each tooth, one was stained with toluidine blue, the other was dried and prepared for scanning electron microscopy. The gram-stained smears demonstrated predominantly gram-positive filamentous microorganisms with an admixture of gram-positive cocci and rods. The ground sections revealed a deposit on the outer surface of the enamel, which was clearly divided into two distinctly different layers: an inner yellow opaque layer, and an outer layer of microorganisms. Scanning electron microscopy demonstrated that the deposit consisted entirely of microorganisms, and that in portions close to the enamel they were often obscured by a substance indicative of calcification. Thus the black stain found on the teeth of Hong Kong Chinese is similar in composition and structure to that reported to occur in other populations. The black stain is a special type of dental plaque characterized by its simple flora and its tendency to calcify.

Adult↗

PubMed1989

Morphology of mineral deposits on encrusted urinary catheters investigated by scanning electron microscopy.

Struvite and hydroxyapatite were precipitated from artificial urine onto the surfaces of catheter materials by the controlled addition of urease. They were precipitated both together and separately (by omitting components of the artificial urine), and with and without the inclusion of albumin (which was intended to mimic the proteinaceous debris found in infected urine). Precipitates were identified by X-ray powder diffraction and the artificially encrusted surfaces examined by scanning electron microscopy. In the presence of protein, hydroxyapatite was precipitated as a poorly crystalline form which aggregated to form a crust. Struvite crystals could be easily identified under the scanning electron microscope by their relatively large size and characteristic appearance. Fifteen encrusted catheters from patients were also examined by scanning electron microscopy, and a further six using X-ray microanalysis. Their appearance was very similar to that of the materials encrusted in vitro. Encrustation involves the formation of hydroxyapatite and the growth of struvite crystals, intimately associated with bacteria.

Durapatite↗

PubMedDate not supplied

Cause of spontaneous echocardiographic contrast as assessed by scanning electron microscopy.

Spontaneous echo contrast ("echocardiographic smoke") is known to occur in low-flow states and to require the presence of red cells and plasma proteins. Limited morphologic information regarding the microanatomic structure of red cells exhibiting spontaneous echo contrast is known. The study was designed to evaluate the microanatomic features of red cells exhibiting spontaneous echocardiographic contrast with scanning electron microscopy. With human blood, a beaker, and a stirring bar, a simple model for demonstration of spontaneous echo contrast and its reversal was devised. Blood elements were "sampled" from within this model at times of high and low spontaneous echogenicity by adherence of blood elements to poly-L-lysine-coated slides that were subsequently fixed and examined with scanning electron microscopy. Spontaneous echo contrast was maximal at complete stasis or low-flow states and could be abolished by agitation of blood with continuous stirring. Sampling during low-flow states with high echogenicity showed a preponderance of clumped red cells, whereas at high-flow and low echogenicity states red cells were dispersed and usually solitary. No morphologic features suggestive of activation of the coagulation system were noted. Spontaneous echo contrast is caused by reversible red blood cell clumping, which occurs in fresh human blood at low-flow (low shear rate) states and can be abolished by increasing flow. This phenomenon is independent of activation of the clotting system.

Blood Specimen Collection↗

PubMed1989

Sealing root canals with low-viscosity resins in vitro: a scanning electron microscopy study of canal cleansing and resin adaption.

Low-viscosity resins of the fissure sealant type have been suggested in the literature as having potential for use as root canal filling materials. A low-viscosity resin may seal a root canal by flowing into clean dentinal tubules after smear layer removal. This investigation with scanning electron microscopy examines the efficacy of two methods of root canal preparation and the effectiveness of different chemicals on smear layer removal. Ultrasonic preparation with 0.25% sodium hypochlorite solution and final agitation with 50% citric acid solution were found to produce a very clean canal wall, free of smear layer in coronal and middle parts. However, low-viscosity resin used in conditions that aimed to simulate in vivo conditions failed to penetrate open dentinal tubules to a significant extent. On the basis of these observations made with scanning electron microscopy, low-viscosity resins would not seem suitable as root canal filling materials, because they are unlikely to form a satisfactory adaption to the canal wall. In addition, if treatment fails, these resins are impossible to remove from a root canal without much destruction of tooth substance.

Citrates↗

PubMed1999

Lumbar dura mater biomechanics: experimental characterization and scanning electron microscopy observations.

UNLABELLED: There is no consensus about the anatomical structure of human dura mater. In particular, the orientation of collagen fibers, which are responsible for biomechanical behavior, is still controversial. The aim of this work was to evaluate the mechanical properties and the microstructure of the lumbar dura mater. We performed experimental mechanical characterization in longitudinal and circumferential directions and a scanning electron microscopy observation of the tissue. Specimens of human dura mater were removed from the dorsal-lumbar region (T12-L4/L5) of six subjects at autopsy; specimens of bovine dorsal-lumbar dura mater were obtained from two animals at slaughter. Human and bovine tissues both exhibited stronger tensile strength and stiffness in the longitudinal than in the circumferential direction. Scanning electron microscopy observations of dura mater showed that the collagen fibers are mainly oriented in a longitudinal direction, which accounts for its stronger tensile strength in this direction. We conclude that dura mater has a different mechanical response in the two directions investigated because the fiber orientation is predominantly longitudinal. IMPLICATIONS: In this experimental work, we studied the structural and functional relationship of human lumbar dura mater. We performed mechanical tests and microscopic observations on dura mater samples. The results show that the dura mater is mainly composed of longitudinally oriented collagen fibers, which account for higher tissue resistance in this direction.

Adult↗

PubMed1996

Morphometry, scanning electron microscopy and X-ray spectral microanalysis of protostylid pits on human lower third molars.

Protostylid pits on 50 lower third molars were studied. The depth and width of the pits, the thickness of the enamel at the pit bottom and the concavity of the dentino-enamel junction under the pit were measured by light microscopy. The pit content was examined by scanning electron microscopy and X-ray spectral microanalysis. The results show that the morphometric variables of protostylid pits are similar to those of occlusal fissures and pits. The protostylid pits were seen to contain globular formations, belonging mainly to dental calculus; organic rod-shaped bodies, which could represent remnants of the enamel organ--or more probably--foreign bodies, were frequently observed. The study suggests that the development of the most common form of protostylid is basically similar to that of an occlusal cusp, with variations attributable to the low expression of the protostylid and particularities of cusp development in the lateral tooth wall.

Calcium↗

PubMed1989

Comparison of backscattered scanning electron microscopy and microradiography of secondary caries.

Carious lesions are usually studied using light microscopy and/or microradiography which require preparation of thin sections. Backscattered scanning electron microscopy (BSEM) has received little attention although it provides information similar to that obtained with microradiographs, with the potential for higher resolution. Recently, microscopes have been introduced that can be used to study wet or nonconducting specimens, offering techniques for studying specimens without desiccation or preparation of thin sections. This investigation sought to determine if secondary carious lesions have the same characteristics when studied by microradiography as when using the "wet" BSEM mode. Microradiographs were made of thin sections from restored teeth with secondary caries induced in an artificial caries system. The thin sections were also studied by BSEM with a partial pressure in the specimen chamber to prevent specimen charging. Comparisons of the lesion size and shape were made using the two methods. Lesion depth measurements in enamel were the same; lesions that penetrated into dentin appeared to be of similar size and shape, but lesion depths measured by BSEM were slightly greater (paired t-test, p less than .05). This was a result of cracks at the carious enamel-dentin interface that probably developed during storage of the samples. Variations in the surface enamel rod structure and the development of subsurface lesions were apparent. Several zones were also apparent in the carious dentin, demonstrating loss of dentinal tubule detail in the depth of the lesion, collapse of tubules, and hypermineralized regions near the advancing front of the lesion. Several additional samples of natural carious teeth were examined. They demonstrated the characteristic structural features of the carious process.(ABSTRACT TRUNCATED AT 250 WORDS)

Dental Caries↗

PubMed1980

Using expanded polytetrafluoroethylene for bridging arterial microvascular defects: an experimental study with evaluation in the scanning electron microscopy.

In an experimental investigation the replacement of arterial microvessels with microporous expanded polytetrafluoroethylene was studied. The infrarenal segment of the rat aorta was used as the scientific model. The inside diameter of the micrograft was 1 mm. Using microvascular techniques a total of 18 prostheses were inserted. The animals were harvested at time intervals from 3 days up to 3 months. Patency was determined by angiography and at autopsy. The aorta implant junction, the characteristics of the neointima development and the differentiation of the interstitial cells were studied by scanning electron microscopy. Fourteen of the implanted micrografts remained patent at the time of sacrifice, yielding an early patency rate of 77,7%. As shown by scanning electron microscopy, the development of the neointima took place in 2 stages. The initial fibrin/platelet layer was reduced after one month and replaced by a definite neointima with mononuclear cells, connected with interstitial cells. Investigation of the aorta-implant junction showed the prosthesis functionally embedded in the structure of the aorta. Expanded polytetrafluoroethylene as a prosthetic material for microvascular prostheses was easy to handle and emerged compatible with other tissues. It can be used as a substitute for bridging arterial microvascular defects.

Animals↗

PubMed1996

First clinical application of the Medos-HIA ventricular support system: monitoring of the thrombotic risk by means of the biomarker prothrombin fragment F1 + 2 and scanning electron microscopy evaluation.

BACKGROUND: The medos-HIA ventricular support system was designed as an artificial heart assist device for intractable heart failure to act as a bridge for transplantation or recovery. The aim of this study is to report on the first clinical application of the system and to evaluate the thrombotic risk with the use of the biomarker prothrombin fragment F1 + 2 and scanning electron microscopy of the blood contacting surface. METHODS AND RESULTS: This device worked without any failure for 462 hours, and a sufficient output of 5.2 to 6 L was observed. No activation of the procoagulatory system occurred during pumping until the occurrence of the septicemia. Preseptic F1 + 2 levels were normal, at about 1 nmol/L. The blood contacting surfaces of the pump and the polyurethane valves were examined by means of scanning electron microscopy, and the surfaces were found to have smooth fibrin layers with no thrombogenic deposits. This fibrin layer is considered to prevent thrombotic adhesions, thereby minimizing the risk of thromboembolic complications. Post mortem examinations after pneumonia with septic shock showed no thrombus formation in this support system and around the inserted cannulas. CONCLUSIONS: The low risk for thromboembolic complications, no measurable activation of the coagulation system, and the excellent surface characteristics encourage further use of this inexpensive working device.

Cardiac Output↗

PubMedDate not supplied

Scanning electron microscopy of aberrant crypt foci in human colorectal mucosa.

BACKGROUND: Aberrant crypt foci (ACF) are clusters of morphologically altered crypts which can be observed by light or stereomicroscopy on the mucosal surface of the colon after staining with methylene-blue. They probably represent one of the earliest events in human colorectal carcinogenesis. The main purpose of the present study was to observe the surface features of aberrant and normal colonic crypts in humans using scanning electron microscopy (SEM) in order to find and measure differences between aberrant and normal. MATERIALS AND METHODS: Fifteen mucosal specimens containing ACF and 8 with normal mucosa taken from patients operated on for colon cancer were observed under a scanning electron microscope. RESULTS: By SEM ACF were easily observed on the mucosal surface, because they showed a well defined border and were elevated on the mucosal surface. Under higher magnification luminal openings of aberrant crypts had a larger overall average diameter than normal (37.6 microns +/- 13.5, mean +/- SD, vs 15.9 microns +/- 4.9, P = 0.001), though when crypt multiplicity of ACF (number of crypts per ACF) was higher, the diameter of luminal openings tended to be smaller and similar to those of normal crypts, with weak negative correlation between crypt multiplicity of ACF and mean diameter of aberrant luminal openings (r = 0.27). Finally, the mucosal surface among aberrant crypts was flattened because of a loss of microvilli. in conclusion, scanning electron microscopy allows a better definition of the topological features of aberrant crypt foci than light or stereomicroscopy.

Colon↗

PubMed1999

Scanning electron microscopy of the floor of the fourth ventricle in rats subjected to graded impact injury to the sensorimotor cortex.

OBJECT: Respiratory dysfunction including apnea frequently follows head injury in humans. The purpose of this study was to identify any structural alterations in the region of brainstem respiratory nuclei that might account for immediate postinjury respiratory abnormalities in anesthetized experimental animals. METHODS: Using scanning electron microscopy, the authors examined the floor of the fourth ventricle in injured rats after a piston strike to the sensorimotor cortex that depressed the dura 1, 2, or 4 mm. The rats were killed within minutes of injury. Cortical impact depths measuring either 1 or 2 mm (eight rats) produced no respiratory abnormalities, and the structural integrity of the ependymal lining of the ventricular floor in these animals was not compromised. Thirteen rats were subjected to impact to a 4-mm depth and 10 of these exhibited immediate temporary or permanent apnea. The medullae of nine of these rats were studied using scanning electron microscopy, and the fourth ventricular floors of all nine rats showed tears. Four rats that exhibited immediate, permanent apnea had tears in the caudal fourth ventricle floor near the obex, whereas five rats with no or only transient apnea had tears located more anteriorly, near the aqueduct or laterally. Changes in cerebrospinal fluid flow or pressure dynamics may have caused these tears. Light microscopy, focused near the area postrema, revealed a shearing defect through the ependyma of the fourth ventricular floor into the subjacent neuropil with a disruption of axonal pathways. CONCLUSIONS: Respiratory neuronal network components lying within 2 mm of the area postrema may well have been disrupted by the caudal tears producing permanent apnea. A similar phenomenon could account for the transient or permanent postinjury apnea seen in humans with severe head injury.

Animals↗