SEARCH · PubMed Health

Results for “scanning electron microscope”

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 901 records · Page 50Linked to original sources

PubMed1995

Scanning electron microscopic observations of nerves in the guinea-pig gallbladder after an acetylcholinesterase histochemistry.

Three-dimensional structures of the nerves of the guinea-pig gallbladder, after histochemical demonstration of the acetylcholinesterase activity and HCl hydrolysis-collagenase digestion, were examined by scanning electron microscope. HCl-collagenase digestion facilitated easy identification of silver- and gold-intensified acetylcholinesterase-positive nerve fibers at a high accelerating voltage (25 kV), due to their strong reflection image. Ganglia were either triangular or ovoidal in shape. Dense para- and peri-vascular nerve fibers occurred around the cystic artery. There were a few intramuscular nerve fibers with varicosity-like structures among smooth muscle bundles. Dense branched and tapering nerve fibers with varicosities in the lamina propria mucosae were closely attached to epithelial cells. The acetylcholinesterase-positive fibers in the lamina propria and peri- and para-vascular nerves, and fewer positive fibers in the smooth muscle layer probably represent cholinergic nerves involved in the concentration of biliary compounds and lesser in the motor function of the smooth muscle.

Acetylcholinesterase↗

PubMed1991

Thermomechanical compaction of gutta-percha: a scanning electron microscope study.

The root canals of 20 freshly extracted maxillary central incisors and canines were prepared and filled by thermo-mechanical or lateral condensation of gutta-percha cones without sealer. The adaptation of the filling material to the root canal walls was then examined with a scanning electron microscope. A more homogenized mass of gutta-percha could be detected in teeth filled by thermomechanical compaction of gutta-percha cones. The morphology of the prepared root canal system was well reproduced by the use of both techniques.

Dental Pulp Cavity↗

PubMed1977

Thrombogenic properties of arterial catheters: a scanning electron microscopic examination of the surface structure.

We performed 300 consecutive coronary arteriographies with 2 different kinds of catheters: polyurethane catheters and polyethylene catheters. The thromboembolic complication rate for investigations with each type of catheters is compared to the surface structure as seen with the scanning electron microscope (SEM). The complication rate was 21.4% for polyurethane catheters and 0.3% for polyethylene catheters. The inner surface of polyurethane catheters was irregular, while the inner surface of polyethylene catheters appeared smooth. The outer surface of polyurethane catheters was slight irregular, while the outer surface of polyethylene catheters was smooth. These results are compared to other investigations of the surface structure of coronary catheters and to reports on the thromboembolic complication rate at coronary arteriography. It is concluded that the 2 types of catheters have different thrombogenic properties and that the surface structure is of major importance for this difference.

Cardiac Catheterization↗

PubMed1991

[Transitional mucosa in carcinoma of large bowel. Mucin histochemical and scanning electron microscopical study].

We studied the mucosa close to the carcinoma of large bowel (CLB) in 200 cases, the carcinoma tissue of CLB in 130 and the mucosa of fetus large bowel in 24 by mucin histochemistry, in addition to the mucosa near CLB studied by scanning electron microscope (SEM) in 25. The results suggested that mucin composition of transitional mucosa (TM) was similar to CLB and large bowel mucosa of the fetus. SEM showed significant changes in TM. The HID/AB Stain suggesting abnormal range of TM was within 2 cm in 68.0% (136/200) of cases of CLB, within 3 cm in 88.5% (177/200) and In SEM abnormal range within 2 cm in 88.0% (22/25). The measurement of TM can provide reference for resectable range of CLB.

Colonic Neoplasms↗

PubMed2001

[Evaluation of the surface of the new intraocular lenses in the scanning electron microscope].

PURPOSE: To evaluate the surface of the new PC IOLs commercially available in Poland in 2000. MATERIAL AND METHODS: Representative samples of new posterior chamber IOLs produced by 6 different companies (Alcon, Lensita, Medicontur, Opsia, Rayner, Storz), 5 of each, underwent surface examination with Novoscan 30 scanning electron microscope. RESULTS: Although, in general, smooth surface of optic and haptic parts were observed, three samples with irregularities were found. CONCLUSIONS: Comparing to previous evaluation performed in 1994, significant improvement in quality of IOLs surface was noted. No considerable differences in this field between above mentioned producers were observed.

Biocompatible Materials↗

PubMedDate not supplied

Observation of an amalgam-bonded tooth through a scanning electron microscope.

Bonding dental amalgam to tooth reduces the occurrence of marginal leakage, fracture and sensitivity. However, most studies of amalgam bonding have made use of resin cements and the conventional three-bottle bonding agents. In this study, a newer, single-bottle bonding agent was used to bond amalgam both to dentin and enamel. Interfaces of bonded amalgam and unbonded amalgam were observed under the scanning electron microscope.

Bicuspid↗

PubMedDate not supplied

Scanning electron microscopic appraisal of a new micro T-tube.

A new micro T-tube, 0.6 mm in outer diameter, has been constructed. Use of this tube has allowed 1-mm common carotid artery (CCA) bypass ofr periods of time up to 22 minutes. After bypass, scanning electron microscopic observation of sutured CCA endothelium showed widespread destruction, scattered attached platelets and other formed blood elements, as well as microthrombi both at suture lines and in areas in contact with T-tubes. Despite microthrombi, 41 of 42 CCAs were patent after anastomosis. Silicone cuffs and 8-0 ties secured T-tubes inside vessels with no apparent difference in underlying endothelial destruction.

Animals↗

PubMed2005

Scanning electron microscopic observation of the brown tumor of the head of mandible.

Brown tumors are tumor-like, expansile osteolytic lesions of bone which are seen in both primary and secondary hyperparathyroidism. They generally resolve after surgical treatment of the parathyroid adenoma. Here, we report a case of brown tumor of the mandible of a cadaver with its scanning electron microscopic observation and review of literature.

Cadaver↗

PubMed1983

Scanning electron microscopic studies of the hyaloid vascular system in newborn mice exposed to O2 and CO2.

It has been suggested that the tunica vasculosa lentis of newborn mice undergoes vasoproliferation after oxygen exposure and might be used as an experimental model for intraocular neovascularization. A scanning electron microscopic technique which provides visualization of the entire hyaloid vascular system was used to study its response in mice exposed to various gas mixtures (70% O2/30% N2, 10% CO2/90% air, 10% CO2/70% O2/20% N2). Marked differences were found between hyaloid regression in gas exposed mice compared to air control mice, but no evidence of neovascularization was found in any group. The data support the possibility that changes in the hyaloid may be the consequence of the hydrostatic coupling which exists between this atrophic, possibly flow-resistant vasculature and the developing retinal vasculature whose blood flow characteristics are significantly altered by exposure to CO2 and O2.

Age Factors↗

PubMed2006

Allograft semilunar cardiac valves processing and cryopreservation - morphology in scanning electron microscope.

OBJECTIVE: The most important factors of long term clinical performance of biological heart valve prostheses are methods of processing and cryopreservation. That is why we decided to evaluate the impact of current Allograft Heart Valves (AHV) Bank protocol on valve tissue morphology. Scanning electron microscope (SEM) is a valuable tool for investigation of biological surfaces. In case of cardiac valves it is especially suitable for detection of fine changes in endothelial covering and underlying layers. MATERIAL AND METHODS: "Fresh" aortic and pulmonary AHV samples, harvested from "heart-beating" cadaveric donors, were compared with (1) tissue from AHV obtained from non heart-beating donors, (2) samples stored in 4 degrees C saline for 24 h, (3) antibiotic treated tissue for 24 h at 37 degrees C and finally (4) cryopreserved valves, stored in liquid nitrogen (-196 degrees C) for 6-38 months. All samples were dissected, dried with hexamethyldisilazane (HMDS), gold coated, studied and photographed by SEM (Tesla BS 301). RESULTS: Our alternative method of drying samples by the HMDS method proved to be suitable for thin membranes of human semilunar valves. We were able to detect early changes in the endothelium after harvesting, and denudation of the endothelial covering during preservation with and without freezing. CONCLUSION: SEM (using HMDS drying) along with other methods may be helpful for the morphological control of processing, cryopreservation and liquid nitrogen storage of AHV. According to the current findings we have to avoid washing of AHV in saline after harvesting.

Cryopreservation↗

PubMed1980

Laser coagulation in the upper GI tract: a preliminary light and scanning electron microscopic study.

Experimentally intact as well as artificially damaged mucosa of porcine stomach was endoscopically coagulated with Nd:YAG laser beams. Energy, intensity pattern, and time of application of the irradiation was varied and supracellular changes of the coagulated mucosa were subsequently investigated with the scanning electron microscope. The mucosa, damaged by laser beams, showed three typical zones: 1. a superficial, central carbonisation zone protected with a thin layer of coagulated mucus; 2. an elevated hyperemic ring with complete loss of superficial epithelium, but intact basement membrane and a blood clotting of the mucosal capillaries; 3. normal mucosa. After coagulating artificially induced bleeding of the mucosa the irradiated centre showed a deep depression with a carbonized surface. Two weeks later regeneration had occurred and there was complete reepithelialisation of the mucosa to about two-thirds of normal thickness.

Animals↗

PubMed2001

High-resolution scanning electron microscopic evaluation of cell-membrane porosity by ultrasound.

The effect of low-intensity ultrasound on HL-60 cells (human promyelocytic leukemia cells) in the presence of the photo sensitizing drug merocyanine 540 (MC 540) was evaluated morphologically, using a high-resolution scanning electron microscope and a transmission electron microscope. Exposure of HL-60 cells to ultrasound without MC 540 resulted in a decrease of finger-like processes in the cells. The cells showed many undulating ruffles on the surface. Distinct pits or holes in the membrane were not observed in these cells. The surface of HL-60 cells treated only with MC 540 was relatively smooth compared with that of control cells. HL-60 cells exposed to ultrasound in the presence of MC 540 showed apparent surface deformation. Numerous crater-like depressions of heterogeneous dimensions were observed in many cells. In addition, various-sized pores were noted in the cell membranes of more damaged cells. These results indicate that cell degeneration was induced by a rapid change in cell membrane porosity during sonication in the presence of MC540.

Apoptosis↗

PubMed1979

An evaluation of the root topography following periodontal instrumentation--a scanning electron microscopic study.

Extraction was performed on 52 periodontally involved teeth. Of these, ten without any instrumentation served as controls, 19 were treated with hand instruments, and 23 with ultrasonics. The extent of cleaning and damage to teeth with the two treatment procedures employed were assessed by examining in the scanning electron microscope. Ultrasonics were superior in the treatment of incisor teeth but had no particular advantage over the hand instruments with respect to the treatment of molars. Also the microflora forming the bacterial plaque were visualized.

Adult↗

PubMed1981

The efficacy of several irrigating solutions for endodontics: a scanning electron microscopic study.

The perforated irrigation needle was used to test a high-volume (20 c.c.) final flush of prepared root canals. Three solutions: TEGO 1 percent, NaOCl 5.25 percent, and REDTA were tested. The roots were split longitudinally and were prepared for examination under the scanning electron microscope immediately after preparation and final flushing. In addition, groups were prepared and flushed in the same manner, but after splitting they were soaked in the respective solutions for 3 hours and then examined. The results indicated that the smeared layer is caused by instrumentation, that it is not removed by TEGO or NaOCl, and that it is removed by REDTA. It may be that the smeared layer is a slurry of dentin filings, since REDTA does not remove soft tissue. All solutions produced a canal quite free of debris; however, none of the tested irrigants was completely satisfactory by itself.

Dentin↗

PubMed1998

T (Thomsen-Friedenreich) and Tn epitope location and their spatial relations to adhesion plaques on human breast carcinoma cells: immunogold-silver staining studies at scanning electron microscopic level.

T and Tn are pancarcinoma epitopes (EPs) which can be immunodetected in about 90% of adenocarcinomas (CAs). To study the location of T and Tn EPs and their relations to adhesion plaques on CA cells, immunogold-silver staining method was employed at scanning electron microscope (SEM) level. Human breast CA cells grown on coverslips were fixed in paraformaldehyde and glutaraldehyde, reacted with cocktails of monoclonal antibodies against T or Tn EPs, followed by incubation with 10 nm gold conjugated goat anti-mouse immuno-globulins. The positive gold particle labelling was amplified with silver enhancement solution, and the specimens were then routinely critical point dried, sputter-coated with palladium and observed under SEM. The studies show that T and Tn EPs are not randomly distributed on CA cell surface; they are aggregated at the adhesion plaque area. These results confirm that T and Tn EPs play roles in CA cell adhesion, and suggest that they may represent the initial points of contact by immuno-effectors and therefore can be utilized in immunointervention and anti-adhesion therapy against CA.

Antigens, Tumor-Associated, Carbohydrate↗

PubMed1982

Eyelid growth and fusion in fetal mice. A scanning electron microscope study.

During the last phase of mammalian morphogenesis, between days 14 and 16 of gestation in the mouse, the fetal eyelids grow across the eye and become tightly fused with each other. This paper describes the surface pattern of fetal eyelids, revealed by the scanning electron microscope, during normal eyelid growth and fusion in the ICR/MI stock of mice. Fusion proceeds from both inner and outer canthi and progresses toward the middle of the gap. The first changes in cell shape and distribution occur at the inner canthus. On day 14, a large clump of rounded cells appears on the inner surface of the inner canthus. A day later, two clumps of rounded cells are positioned to either side of, i.e. above and below, the inner canthus. As fusion progresses, the diminishing gap fills with a profusion of rounded cells that are extruded, flattened, and sloughed off from the area of completed fusion. The profusion of rounded surface cells during eyelid growth and fusion appears to be a major characteristic in which the eyelid fusion process differs both from permanent fusions, such as the fusion of the neural tube, lip or palate, and from other temporary fusions, such as fusion of the digits to each other or of the pinnae to the scalp.

Animals↗

PubMed1984

Neodymium YAG laser effects on rabbit lenses. A scanning electron microscopic investigation using Q-switched and mode-locked lasers.

The immediate and long-term effects of Q-switched and mode-locked neodymium (Nd) yttrium-aluminum-garnet (YAG) lasers on the fine structure of lens fibers were studied with stereomicroscopic and scanning electron microscopic methods. This study shows that both laser systems produced very restricted lesions that, at a 1-h survival time, were characterized by an empty central hole surrounded by a thin amorphous wall. Fibers adjacent to the hole looked normal, apart from some compression in the immediate vicinity of the hole. At medium and long-term survival times the empty bubbles now appeared to be filled with a crystal-clear amorphous mass. The wall surrounding the empty lesions had disappeared, and at medium survival times adjacent fibers incidentally showed fiber alterations like local swellings and microplicae. At 180 days the fibers surrounding the central mass showed numerous swellings, microplicae and confluence of fibers. These fiber alterations are also seen in different types of cataracts. Thus, short-pulsed laser lesions may act as cataractogenic centers.

Animals↗

PubMed1985

Examination of explanted polyurethane pacemaker leads using the scanning electron microscope.

Since 1978, 2,365 polyurethane (PU) insulated cardiac pacing leads were implanted transvenously at our institution. To date, there have been no insulation failures in those leads. Thirty-seven PU leads were explanted, mainly for exit block, and 28 of these were investigated using the scanning electron microscope. We found a homogeneous distribution of surface changes in all lead segments in 56% of the 28 examined. These changes were more pronounced at the ligature site; severe surface cracking was noticed in 21%, with the deepest crack being 40 micron (average range of 10-15 micron). There appeared to be no time-dependency of the surface changes as indicated by regression analysis (r = 0.32, p greater than 0.05). The ultimate severity and outcome of this degradation process in the leads reported in this study will only be known in the future after longer use. We conclude that excess stress must be avoided during the implantation procedure and that careful surveillance is necessary.

Equipment Failure↗