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At least 991 records · Page 55Linked to original sources
PubMed1982

Fibrous structures of human chromosomes observed by scanning electron microscopy.

Human chromosomes and the nucleus from cultured HeLa cells and lymphocytes were observed stereographically by scanning electron microscopy. Specimens were heated in an acetic acid solution after treatment with diluted McIlvain's buffer solution at pH 5.6. The cytoplasmic matrix adhering to the chromosomes was successfully removed, and the chromosomes were observed three-dimensionally in their original position without any significant mechanical distortion. The interphase nucleus was spherical in shape and the nuclear membrane could not be seen on its surface. The chromosome fibres were 25-35 nm in diameter and showed bumpy, looping, tortuous and knotty appearances at high magnification.

Cell Nucleus↗
PubMed1978

Surface morphology of polyvinyl chloride and silicone elastomer umbilical artery catheters by scanning electron microscopy.

The surface features of a new silicone elastomer umbilical artery catheter have been defined by scanning electron microscopy and compared with those of a standard polyvinyl chloride catheter. Little difference was noted in the surfaces of the catheter materials themselves, but the radiopaque material used to render the catheters visible by x-ray resulted in a considerable difference in the overall smoothness. The polyvinyl chloride catheter's marker was in the form of a wide, rough band extending the length of the tubing whereas the marker particles of the silicone elastomer were dispersed, more uniform in size, and resulted in less overall irregularity of the surface.

Catheterization↗
PubMedDate not supplied

The collagen skeleton of the cat testis. A scanning electron microscopy study after 2N-NaOH maceration.

Testes from adult cats were studied by means of scanning electron microscopy (SEM) after 2N-NaOH maceration method which selectively digests cells and tissue compounds. As seen by this technique, the testis appears covered by a dense fibroconnective tunica albuginea that divides partially the organ by sending septa into the parenchyma. The interstitium is made up by a rich connective tissue composed by randomly-arranged fine collagen bundles that clearly outline the spaces occupied by the seminiferous tubules. The basement membrane of the seminiferous tubules consists in two rough layers of collagen fibers that in some places leave small fenestrations. The three-dimensional arrangement of collagen fibers in the interstitium outlines a system of cavities likely to be lacunar spaces for Leydig cells and vascular imprints. Especially, the above chemical technique followed by deep observations under the SEM allowed a clear and complete view of the real three-dimensional microarchitecture of the connective tissue of the testis. Therefore, the collagen component was revealed to actually form a unique and complex skeleton for the whole organ. This three-dimensional figure closely follows indeed the classical histological compartmentalization of the testis with a better insight of its spatial microtopographical features. Moreover, this structural pattern is also likely to give rise to very fine morphofunctional subcompartmentalization, especially regarding the basement membrane of the seminiferous tubules and the lacunar spaces for Leydig cells including satellite vessels.

Animals↗
PubMed1996

[Chronic autoimmune thrombocytopenia in the spleen and microparticles as seen in scanning electron microscopy].

In chronic autoimmune thrombocytopenia numerous round formations in the sinus lining cells are observed by scanning electron microscopy. They occur sometimes on the surface of erythrocytes passing through the sinus wall. It is possible that they are not cytoplasmic processes but platelet microparticles sticking on the surfaces of various cells. These particles are too small in routine counting of blood platelets in the light microscopy and probably too fragile in examining in transmission electron microscopy.

Autoimmune Diseases↗
PubMed1996

Scanning electron microscopy of cyclosporine-induced gingival overgrowth.

Overgrown human gingival specimens were examined histologically and by scanning electron microscopy (SEM) to study structural changes caused by cyclosporine. The biopsy specimens were from organ transplant recipients receiving cyclosporine to suppress the rejection of the transplanted organ. The epithelium of the overgrown gingiva was thickened, acanthotic and parakeratotic. Retepegs were anastomosing and extending into connective tissue. The SEM examination of the outer surface of the attached gingival showed loss of cellular attachments and cells were exfoliating. The normal honeycomb structure formed by interconnecting microvilli surrounding the pits was distorted. Outer gingival cell surface showed numerous round, ovoid and dome-like structures instead of parallel, reticular or fingerprint-like microridges. It was concluded that cyclosporine not only caused hyperplasia but also changed the structure of the outer epithelial cell surface.

Cyclosporine↗
PubMed1991

Alcoholic cirrhosis and osteoporosis in men: a light and scanning electron microscopy study.

Subjects with chronic alcoholism are associated with a higher prevalence of bone fractures, compared with age-matched controls. However, the pathogenesis of alcoholic osteopathy remains poorly understood. In this study, the bone cells activities and the bone matrix were studied using different techniques such as bone morphometry, scanning electron microscopy and computer reconstruction. Male patients (N = 20), aged 59.1 +/- 10.1 years, presenting a chronic decompensated alcoholic cirrhosis, were admitted into this study. A histomorphometric analysis of a transiliac bone biopsy was done after a double tetracycline labeling of the bone. A scanning electron microscopy (SEM) study was performed on eight out of the 20 patients on an additional biopsy. The bone mass was significantly decreased in cirrhotic patients. A marked defect in the osteoblastic function was observed with reduced osteoid parameters, lower mean wall thickness, and slower bone formation rate leading to a thinning of bone trabeculae. Conversely, trabecular resorption surfaces were markedly increased. SEM examination of bone biopsies was also consistent with delayed and impaired osteoblastic activity leading to extended and scalloped resorption surfaces covered by unusually thin layers of calcified collagen fibers. The reduced osteoblastic activity associated with normal osteoclastic function appears to play a major role in the pathogenesis of alcoholic osteoporosis leading to decreased bone mass with thinner trabeculae.

Aged↗
PubMed1995

Bone resorption in human cholesteatoma: morphological study with scanning electron microscopy.

The detailed mechanism of bone resorption in cholesteatoma was investigated by means of eroded ossicles obtained during middle ear surgery for cholesteatoma. In the light microscopic study, multinucleate osteoclasts with ruffled borders were found in contact with the eroded bone, which appeared to be osteoclastic lacunae. Scanning electron microscopy revealed the lacunae to be many absorption bays, 30 to 100 microns in diameter, clustered on the surface of eroded areas. Numerous cone-shaped stubs of digested collagen fiber bundles, consisting of scores of collagen fibrils and degenerated extracellular organic substances, were visible at higher magnification on the bottom of the absorption bay. The pattern of fusion and twining of the disarranged collagen fibrils at the top of the partly digested fiber bundles was clearly rendered by the alkali-water maceration method for scanning electron microscopy. We infer from the morphological evidence that osteoclastic resorption may be one of the major mechanisms of bone destruction in cholesteatoma, and that demineralization and degeneration of extracellular organic substances precede disruption of collagen fibrils at the front of bone resorption.

Bone Resorption↗
PubMed1991

Lung dust content in idiopathic pulmonary fibrosis: a study with scanning electron microscopy and energy dispersive x ray analysis.

Examination with an optical microscope and polarised light is not sensitive enough to detect low diameter asbestos fibres. This limitation implies that some cases of asbestosis can be erroneously diagnosed as idiopathic pulmonary fibrosis (IPF) if asbestos bodies are not found in the standard examination of abnormal tissue. To determine whether IPF is over-diagnosed, a study was carried out with scanning electron microscopy (SEM) and energy dispersive x ray analysis (EDXA) on 25 samples previously diagnosed as IPF at the standard examination. Scanning electron microscopy will show the presence of low diameter fibres in the lung without tissue destruction, and these fibres can be identified using EDXA. The quantitative and qualitative results for lung tissue from patients diagnosed as having IPF were compared with the results of the examination of 25 samples of normal lung. Most of the samples from patients diagnosed as having IPF showed only occasional inorganic particles (less than 10 particles/SEM field at 160 x), results equivalent to the results obtained in normal lung. Two cases of IPF, however, showed innumerable asbestos fibres (greater than 100 fibres/SEM field). One of these two patients had an antecedent of brief exposure to asbestos. No environmental antecedent was found in the second patient. Asbestosis was the final diagnosis for these two patients. The examination of inorganic particles in normal lungs showed mainly non-fibrous silicates (61.4%) and particles of heavy elements (34.9%). Only one asbestos fibre was found (0.9%). It is concluded that standard pathological techniques overdiagnose IPF in a few cases in which asbestos bodies are not found with the optical microscope.

Adult↗
PubMed1976

Transmission and scanning electron microscopy of experimentally induced thyroid tumors in rats.

Irradiation of the neck region of 10 days old Wistar rats with 300 rads X-rays and their subsequent treatment with MTU leads to the development of thyroid tumors. The ultrastructure of the thyroid tumors induced was studied by transmission (TEM) and scanning electron microscopy (SEM). In follicular carcinomas, cylindrical or high columnar cells with abundant microvilli, well-developed ergastoplasmic reticulum and a hypertrophied Golgi complex predominate. The cytoplasm of the tumor cells of papillary carcinomas was composed of large pleomorphic cisternae, irregular in shape mitochondria, dense bodies, phagolysosomes and lamellar or multivesicular structures. Scanning electron microscopy revealed in the control animals a regular pattern of thyroid follicles tied to each other by tissue bridges and covered by set of blood and lymph vessels. The relief of the follicular carcinomas was irregular indicating follicles different in size and shape. The internal surface of the neoplastic follicles was also irregular as result of deep invaginations and intrafollicular cell growth. The apical region of the normal and neoplastic thyroid follicular cells was covered with abundant microvilli protruding into the colloid.

Adenocarcinoma↗
PubMed2005

Three-dimensional ultrasound biomicroscopy, environmental and conventional scanning electron microscopy investigations of the human zonula ciliaris for numerical modelling of accommodation.

PURPOSE: Biomechanical modelling of the accommodation process is a useful tool for studying the mechanism of accommodation and presbyopia and can aid in the development of accommodative lens-replacing materials. Existing biomechanical models, however, use a very simplified zonula structure. The aim of this study was to use three-dimensional ultrasonic imaging and scanning electron microscopy to provide a more detailed, three-dimensional description of the structure of the human zonula to improve the modelling of accommodation. METHODS: Five human eyes were examined without invasive manipulation using a custom-made three-dimensional ultrasonic imaging technique that allows scanning of features with a spatial resolution of 30 microm. Environmental and conventional scanning electron microscopy (SEM) provided information to complement the ultrasonic images for use in development of a more anatomically correct finite-element model of the zonula structures. These data along with the material properties of the ocular tissue structures were used to construct an advanced geometric model for finite-element simulation of the accommodation process. RESULTS: Images were obtained through three-dimensional ultrabiomicroscopy (3D-UBM) of anatomical features heretofore not directly imagable in their native state. Ciliary processes and zonula structures were clearly separated by both the 3D-UBM and the SEM methods. It was found that fibres inserting on the anterior and posterior lens capsule emerge anteriorly at the ciliary body. Fibres emerging near the pars plana insert on the lens and the ciliary body. No X-shaped crossing fibres were found. Modelling of the accommodation process with both the simple and the more complex geometric models produced refractive power changes comparable with in vivo findings. CONCLUSIONS: The 3D-UBM allowed examination of zonula structures in their native state with minimized preparation artefacts. While these data were incorporated into a complex and more anatomically correct finite-element simulation of intraocular features including lens, zonular system and ciliary body it was found that a simplified zonular model is sufficient for the numerical simulation of the accommodation process.

Accommodation, Ocular↗
PubMed1996

Air abrasion of failed bonded metal brackets: a study of shear bond strength and surface characteristics as determined by scanning electron microscopy.

Failed bonded orthodontic brackets generally require their replacement with a new bracket. The introduction of air abrasion (microetching) technology to orthodontics may allow for immediate use of these failed brackets. This study compared the in vitro shear bond strengths of previously failed bonded metal brackets (experimental group) subjected to air abrasion with new untreated brackets (control group). All bonding used a light-cured orthodontic bonding system. In addition, representative samples from each group were examined by scanning electron microscopy. The results of this study found no significant differences in shear bond strengths between the two groups. Scanning electron microscopy examination of the air abraded brackets revealed a roughened mesh surface with residual bonded material in the bracket base. This simple technique should allow for the immediate reuse of previously failed bonded metal brackets.

Acid Etching, Dental↗
PubMed1997

Apical tubular network in the rat kidney proximal tubule cells studied by thick-section and scanning electron microscopy.

The apical cytoplasm of several absorbing epithelia contains well-developed apical tubules (AT) which contribute to membrane recycling from endocytic vacuoles to the apical cell membrane. In this study, we examined three-dimensional structures of the AT in rat kidney proximal tubule cells by transmission and scanning electron microscopy. In thin sections, the AT appeared as straight tubules with a rather constant diameter (70-90 nm), but others were curved and, occasionally, branching. No AT were labeled with the marker for the external cell surface (ruthenium red) or exhibited histochemical enzyme activity for lysosomal hydrolase (acid phosphatase). After intravenous injection of horseradish peroxidase, it was absorbed in the kidney proximal tubule cells and the AT were labeled with HRP reaction products. Stereo-viewing of the labeled AT in thick sections revealed that they formed an interconnected tubular network. Scanning electron microscopy allowed a three-dimensional view of the AT, in which a network of branching and anastomosing tubules was revealed. These observations indicate that the AT are intracellular endosomal compartments which form an extensive tubular network in the apical cytoplasm. The possibility that this apical tubular network serves as a large membrane store for membrane recycling is discussed.

Acid Phosphatase↗
PubMed1982

The ultrastructure of the lung after exposure to ionizing radiation as seen by transmission and scanning electron microscopy.

Male mice of the BALB/c strain were exposed at an age of 12-14 weeks, to different doses of X-rays, either to the entire thorax or to the right hemithorax. At various times after exposure mice were sacrificed and the lung was examined by transmission or scanning electron microscopy. Radiation symptoms following exposure to 15-20 Gy can be divided into three phases: Early, from a few hours to a few weeks after exposure, changes in capillary permeability and morphological alterations in all types of lung cells are prominent. At intermediate times, from a few weeks to about 7 months after exposure, the symptoms of radiation pneumonitis arise essentially, as a consequence of the action of radiation on the epithelium of the alveoli, and are characterized by a large increase in size, and probably in number of type II epithelial cells. Scanning electron microscopy brings additional arguments that the lesions in the epithelial cells, mainly of type II, are the principal cause of radiation pneumonitis and that capillary damage probably plays a secondary role.

Animals↗
PubMed1985

Campylobacter pyloridis in peptic ulcer disease: microbiology, pathology, and scanning electron microscopy.

After the recent successful isolation of spiral organisms from the stomach this paper presents the bacteriological and pathological correlation of gastric antral biopsies from 51 patients endoscopied for upper gastrointestinal symptoms. Campylobacter pyloridis was cultured from 29 patients and seen by either silver staining of the biopsy or scanning electron microscopy in an additional three. The organism was cultured from 23 of the 33 (69%) patients with peptic ulcer disease and from within this group 17 (80%) of the 21 patients with duodenal ulceration. It was cultured only once from the 12 normal biopsies in the series but from 27 of the 38 (71%) biopsies showing gastritis. C pyloridis was also cultured from five out of seven of the 14 endoscopically normal patients, who despite this had biopsy evidence of gastritis. It was the sole organism cultured from 65% of the positive biopsies and scanning electron microscopy invariably revealed it deep to the surface mucus layer. C pyloridis persisted in the three patients with duodenal ulcers after treatment and healing. The findings support the hypothesis that C pyloridis is aetiologically related to gastritis and peptic ulceration though its precise role still remains to be defined.

Campylobacter↗
PubMed2005

Investigation of surface changes in different types of ventilation tubes using scanning electron microscopy and correlation of findings with clinical follow-up.

OBJECTIVES: Like all biomaterials, ventilation tubes are subject to formation of bacterial biofilm on their surfaces. There might also be surface changes. This increases the risk of complications associated with ventilation tubes. In this study, we examined two groups of ventilation tubes using scanning electron microscopy (SEM) to investigate biofilm growth and surface deformations. METHODS: There were two different types of ventilation tubes used, the first group consisted of 30 silicone tubes and the second group consisted of 16 ionized, processed silicone tubes. The tube samples included those that were either removed or those that were extruded into the ear canal. We investigated the association between scanning electron microscopy findings and the complications that developed during the treatment. RESULTS: As a result of this study, it is found that the ionized, processed silicone tubes are superior to other silicon ventilation tubes in regard to biofilm growth (z=-3.925, p=0.000, <0.0001) and surface deformations (chi(2)=9.120, p=0.003, <0.01). Furthermore, we observed that as the duration of the ventilation tube application increases, bacterial biofilm growth (chi(2)=10.718, p=0.005, <0.01) and surface deformations (z=-2.940, p=0.003, <0.01) increase. We also observed that biofilm growth and occurrence frequency were related to "otorrhea" (chi(2)=10.258, p=0.036, <0.05) and "plugging" (chi(2)=7.952, p=0.019, <0.05) complications. CONCLUSION: In this study, we show that ionized, processed silicone ventilation tubes are more robust to bacterial biofilm growth compared to other silicone ventilation tubes used in this study and that the "otorrhea" and "plugging" complications are reduced with the decrease of bacterial biofilm growth.

Biocompatible Materials↗
PubMed1986

Hypothalamic neuroendocrine correlates of cutaneous burn injury in the rat: I. Scanning electron microscopy.

Rats were given a standard scald burn on 60% of the body surface or only a sham burn and were sacrificed at intervals from 6 hr to 14 days later. Serum thyroxine (T4), free thyroxine index (FT4I) and triiodothyronine (T3) were depressed compared to values in respective shams as early as 6 hr post-burn. T4 and FT4I were less depressed on post-burn days (PBD) 2-3 than on PBD 1 and then exhibited a further fall. T3 remained depressed through PBD 14. Pineal melatonin content was elevated at 6 hr and fell to the normal daytime range in subsequent samples. The ventral portion of the diencephalon was prepared for scanning electron microscopy. Only in the burned rats and beginning on PBD 2, large numbers of supraependymal neurons (SEN) appeared in the ventricular space attached to the inferior walls and floor of the third cerebral ventricle. Transmission electron microscopy was used to confirm the neuronal nature of the SEN. Viewed by scanning electron microscopy, these persisted through PBD 14. SEN were interconnected by cables of their neurites exhibiting varicosities on individual neurites as they passed over perikarya of other SEN. Some SEN were seen to be only partially emerged from the underlying tissue and others were seen to send a thick process into the hypothalamic tissue. These observations indicate that after peripheral injury there is marked plasticity of the brain in an area thought to control the endocrine systems that show abnormalities after such a peripheral injury. The timing, location and nature of these anatomic changes indicate the possibility that at least some aspects of central nervous orchestration of the endocrine metabolic response to injury may be related to the emergence of a neuronal system receiving or sending messages through the cerebrospinal fluid and/or through new neurite circuits along the surface of the third ventricular wall. These structures may appear in response to initial primary hormonal changes and/or may play a role in maintaining the post-injury hormonal milieu manifested in part by a subsequent second fall in serum T4.

Animals↗
PubMed1994

Some "sealants" seal--a scanning electron microscopy (SEM) investigation.

White spot lesions of enamel around orthodontic brackets as a result of demineralization have been well documented in the orthodontic literature. Various methods of treatment have been attempted to reduce or eliminate this danger. The purpose of this study was to evaluate, by means of scanning electron microscopy, the polymerization of the sealant layer around orthodontic brackets with direct and indirect methods of bonding. Twenty-four sound human lateral maxillary incisor teeth were collected, cleaned, divided equally into four groups A through D, and stored in 70% ethyl alcohol. Their buccal surfaces were pumiced, etched with 37% phosphoric acid for 1 minute, and washed under running water for 30 seconds. Metal brackets were bonded with the chemically cured BIS-GMA resin, Ortho Concise, as follows: group A, indirectly bonded with coping; group B, indirectly bonded without coping; and group C, directly bonded; light activated Transbond was used in group D, directly bonded brackets. After washing in alcohol for 20 seconds, all teeth were dried, and sectioned longitudinally, through the middle of the bracket. All were subjected to 5% hydrochloric acid for 30 seconds and then washed under running water for 30 seconds. After drying and sputter coating, the teeth were viewed under scanning electron microscopy. Groups A and D showed a sealant layer surrounding the brackets and covering the buccal enamel. Groups B and C showed total absence of a cured sealant layer around the brackets or surrounding enamel.(ABSTRACT TRUNCATED AT 250 WORDS)

Bisphenol A-Glycidyl Methacrylate↗