Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Microscopy”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

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

At least 1,675 records · Page 93Linked to original sources
PubMed1980

Calcium deposition in human pituitary adenomas studied by histology, electron microscopy, electron diffraction and X-ray spectrometry.

The incidence and morphogenesis of calcification were investigated by histology, electron microscopy, electron diffraction and X-ray spectrometry in 312 surgically removed human pituitary adenomas. By light microscopy the incidence of calcification was 9%. The calcium deposits were evident in several adenoma types, but were most frequent and extensive in prolactin-producing adenomas. Histologically calcium deposits represented amorphous precipitates and psammoma bodies staining with hematoxylin, the von Kossa technique and alizarin red. By electron microscopy, calcified deposits were noted in the cytoplasm of adenoma cells and extracellular space. Electron diffraction and X-ray spectrometry of intracellular precipitates as well as psammoma bodies showed the presence of phosphate, calcium and organically bound sulphur with a ratio of 3.5:5:2, indicating that they contained calcium hydroxyapatite. Present findings provide evidence that mitochondria with microcrystal deposition of calcium represent the primary sites of calcification.

Adenoma↗
PubMed1996

Cell kinetic analysis of intact rat colonic crypts by confocal microscopy and immunofluorescence.

BACKGROUND & AIMS: Precise quantitative and spatial analysis of cell cycle-related biomarkers in colonic crypts is often vital for studies of colon carcinogenesis and cancer prevention. To overcome the limitations of histology, confocal laser microscopy of microdissected whole crypts was used to quantitate S phase and mitotic cells. METHODS: Microdissected distal colonic crypts were studied in a modified rat starvation refeeding model. S phase cells were labeled in vivo with 5-bromodeoxyuridine. Mitotic cells were labeled with MPM2 (antibody to mitosis-specific epitope) and also assessed for chromatin morphology with propidium iodide. Sequential optical crypt sections, produced by confocal microscopy, were digitally imaged. S phase labeling indices per whole crypt were also compared with those derived by conventional immunohistochemistry. RESULTS: S phase and mitotic cells were clearly discriminated without background staining. The labeled S phase cell number and fraction per whole crypt were significantly decreased with starvation and increased with refeeding. Variability in the labeling index between whole crypts analyzed by confocal microscopy was significantly smaller than between histological crypt sections. Consequently, the intervention contributed to 92.2% of the total variability of the labeling index in whole crypts but only to 59% of the variability in histological sections. CONCLUSIONS: Major limitations of histology are overcome by crypt microdissection and confocal microscopic analysis. The total crypt cell population as well as labeled M phase and S phase cells can be imaged, localized, and quantitated with improved precision.

Animals↗
PubMed1991

The use of fluorescein-conjugated monoclonal antibodies, cell culture and transmission electron microscopy to detect Chlamydia psittaci and associated lesions in experimentally infected mice.

An immunofluorescence test based on a monoclonal antibody (mAb) was used to demonstrate chlamydiae in formalin-fixed and paraffin wax-embedded tissues from 10 adult mice experimentally infected by the oral route with Chlamydia psittaci isolated from the fetal membranes of an aborted ovine fetus. Samples of lung, jejunum and spleen were examined by bright-field microscopy, immunofluorescence and transmission electron microscopy, and were cultured for chlamydia in McCoy cells. These tissues were compared with those of two control mice. All infected mice had splenic hyperplasia and two had pneumonia. The lung appeared to be the target organ for C. psittaci administered by the oral route. Chlamydiae were identified in the lungs of five mice by immunofluorescence, bright-field and transmission electron microscopy. Chlamydiae were cultured from the jejunum of two mice and the spleen of one, but could not be identified at these sites by other methods. Immunofluorescence with an anti-chlamydia mAb was useful for detecting chlamydial antigen in formalin-fixed paraffin wax-embedded samples.

Animals↗
PubMed2002

Immunomagnetic separation reagents as markers in electron microscopy.

Antibodies coupled to magnetic particles have been employed for immunomagnetic cell isolation, but their consequent use for electron microscopy (EM) has not been evaluated. We used commercial antibodies coupled to iron-dextran to isolate T cells and monocytes/macrophages by immunomagnetic adsorption from normal human peripheral blood mononuclear cells. Subsequently, we studied the association of electron-dense immunomagnetic reagents with cell membranes. CD14-positive monocytes/macrophages isolated from fixed peripheral blood mononuclear cells retained electron-dense beads on the plasma membrane, while live cells internalized them. Flow cytometry and electron microscopy measurements of the percentage of cells that bound a CD4-specific immunomagnetic reagent in pan-T cell isolates (containing numerous T cell subtypes) were indistinguishable. The immunomagnetic reagent associated with cells could be secondarily labeled by secondary antibody coupled to colloidal gold. This study shows that these reagents used for cell isolation or just labeling, remain associated with their targets at the cell membrane. Immunomagnetic reagents allow "capturing" of rare cells from complex mixtures, purifying and concentrating them in a single step for subsequent electron microscopy. The large number of commercially available immunomagnetic reagents specific for different human, mouse and rat antigens provides additional resources for visualization of cellular ultrastructure.

Animals↗
PubMed1999

Differential regulation of intracellular Ca2+ signalling induced by high K+ and endothelin-1 in single smooth muscle cells of intact canine basilar artery: detection by means of confocal laser microscopy.

Changes in intracellular calcium concentration ([Ca2+]i) in smooth muscle cells play the key role in regulation of vascular smooth muscle tone and pathogenesis of cerebral vasospasm. In this study, we adopted the confocal laser microscopy to detect the fluorescence signals arising from the individual smooth muscle cells of canine basilar artery. Ring preparations were made, loaded with fluo-3 and changes in fluorescence induced by high K+ and endothelin-1 (ET-1) were measured by confocal laser microscopy. In some unstimulated smooth muscle cells Ca2+ waves arising from discrete region of the cell propagated to the whole cell with a velocity of approximately 10 microm/s. High K+ (80 mmol/L) induced a rapid rise in [Ca2+]i, the peak level being consistently reached approximately 10 s after stimulation. In contrast, the time to peak level of [Ca2+]i induced by ET-1 (0.3 micromol/L) varied widely between 13 and 26 s among individual cells, an indication that the extent of nonuniform coordination of increases in [Ca2+]i in individual cells may be partly responsible for the different time courses of tension development of vascular smooth muscle in response to the vasoactive stimulants. The increase in [Ca2+]i induced by ET-1 was transient but a pronounced and sustained contraction developed further in response to ET-1. Thus ET-1 has a biological property as a potential candidate to elicit cerebral vasospasm. Confocal laser microscopy could be a useful tool to measure the changes in [Ca2+]i in individual smooth muscle cells of cerebral artery.

Animals↗
PubMed1982

Evaluation of fluorescence microscopy for the identification of necrotic myocardium.

The utility of fluorescence microscopy in the evaluation of hematoxylin-eosin-stained sections for the presence of myocardial necrosis was examined. Sixteen human autopsy cases with clinical and pathologic evidence of myocardial infarction were studied. In addition, to better define the sensitivity and specificity of this technique, the hearts of 20 dogs that had undergone experimental coronary occlusion of known duration were studied; the duration of occlusion was three hours in seven dogs, six hours in seven dogs, and seven days in six dogs. In both human and dog studies, hypereosinophilic necrotic fibers in hematoxylin-eosin-stained sections appeared bright yellow by fluorescence microscopy. In myocardium that was shown to be necrotic by triphenyltetrazolium chloride staining and electron microscopy but was not hypereosinophilic, there was no bright yellow fluorescence of myofibers. Our study shows that bright yellow fluorescence is related to hypereosinophilia of myofibers and thus can be used to detect myocardial necrosis. However, since only hypereosinophilic fibers show the characteristic yellow fluorescence, the method appears to offer no distinct advantages over routine light microscopic techniques.

Animals↗
PubMed1982

Carbohydrates in the epithelium lining the seminal vesicle of the rat as studied by histochemical methods of light and electron microscopy.

In the epithelium lining the seminal vesicle of the rat, carbohydrates have been studied by means of histochemical methods of light and electron microscopy. In light microscopy, the free surface and granules of different sizes in the distal cytoplasm of the epithelial cells and lumenal masses of secretions were shown to exhibit positive reactions for carbohydrates with 1,2-glycol and acidic groups and sialic acid residues. In electron microscopy, the surface coat of the plasma membrane, certain elements of the Golgi complexes, dense cores of secretory granules and glycogen particles in the epithelial cells were found to exhibit positive reactions for carbohydrates with 1,2-glycol groupings. The correlated structures and functions of the carbohydrate-containing components have been discussed in the light of the known physiology of the seminal vesicle in the rat.

Animals↗
PubMed2006

Direct observation of amyloid growth monitored by total internal reflection fluorescence microscopy.

Most morphological investigations of amyloid fibrils have been performed with various microscopic methods. Among them, direct observation of fibril growth is possible using atomic force microscopy and fluorescence microscopy. Direct observation provides information about the rate and direction of growth at the single fibril level, which cannot be obtained from averaged ensemble measurements. In this chapter, we describe a new technique for the direct observation of amyloid fibril growth using total internal reflection fluorescence microscopy (TIRFM) combined with amyloid-specific thioflavin T (ThT) fluorescence. TIRFM has been developed to monitor single molecules by effectively reducing the background fluorescence in an evanescent field. One of the advantages of TIRFM is that one can selectively monitor fibrils lying along a glass slide, so that one can obtain the exact length of fibrils. This method was used to follow the kinetics of seed-dependent fibril growth of amyloid beta (1-40). The fibril growth was a highly cooperative process, with the fibril ends extending at a constant rate. Because ThT binding is common to all amyloid fibrils, the present method will have general applicability to the real-time analysis of amyloid fibrils.

Amyloid↗
PubMed2006

High-resolution, high-throughput microscopy analyses of nuclear receptor and coregulator function.

Steroid nuclear receptors are ligand-dependent transcription factors that have been studied since the early 1960s by principally biochemical and reporter assay approaches. From these studies an elegant and complex model of nuclear receptor transcription regulation has been developed. Inherent to both biochemical and reporter assay approaches is the generation of averaged responses and it is not generally considered that individual cells could exhibit quite varied responses. In some cases, recent microscopic single-cell analyses provide markedly different responses relative to traditional approaches based on population averaging and underscore the need to continue refinement of the current model of nuclear receptor-regulated transcription. While single-cell analyses of nuclear receptor action have been hindered by the predominantly qualitative nature of the approach, high-throughput microscopy is now available to resolve this issue. This chapter demonstrates the utility of high-throughput microscopic analyses of nuclear receptor and nuclear receptor coregulator function. The ability of high-throughput microscopy to generate physiologically appropriate test populations by filtering based on morphological and protein of interest expression criteria is demonstrated. High-resolution, high-throughput microscopy is illustrated that provides quantitative subcellular information for both androgen and estrogen receptors. Efforts are ongoing to develop model systems that provide additional multiplex data and with refined image analyses to achieve true high-content imaging screens.

Algorithms↗
PubMed1989

Fluorescence microscopy in three dimensions.

The combination of the specificity provided by fluorescence microscopy and the ability to quantitatively analyze specimens in three dimensions allows the fundamental organization of cells to be probed as never before. Key features in this emergent technology have been the development of a wide variety of fluorescent dyes or fluorescently labeled probes to provide the requisite specificity. High-quality, cooled charge-coupled devices have recently become available. Functioning as nearly ideal imagers or "electronic film," they are more sensitive than photomultipliers and provide extraordinarily accurate direct digital readout from the microscope. Not only is this precision crucial for accurate quantitative imaging such as that required for the ratioing necessary to determine intracellular ion concentrations, but it also opens the way for sophisticated image processing. It is important to realize that image processing isn't simply a means to improve image aesthetics, but can directly provide new, biologically important information. The impact of modern video microscopy techniques (Allen, 1985; Inoué, 1986) attests to the fact that many biologically relevant phenomena take place at the limits of conventional microscopy. Image processing can be used to substantially enhance the resolution and contrast obtainable in two dimensions, enabling the invisible to be seen and quantitated. Cells are intrinsically three-dimensional. This can simply be a nuisance because of limited depth of focus of the microscope or it could be a fundamental aspect of the problem being studied. In either case, image processing techniques can be used to rapidly provide the desired representation of the data. In this chapter we have discussed the nature of image formation in three dimensions and dealt with several means to remove contaminating out-of-focus information. The most straightforward of these methods uses only information from adjacent focal planes to correct the central one. This approach can be readily applied to virtually any problem and with most commonly available image processing hardware to provide a substantially deblurred image in almost real time. In addition to covering more sophisticated algorithms where the utmost in three-dimensional imaging is required, we have developed a method for extremely rapidly and accurately producing an in-focus, high-resolution "synthetic projection" image from a thick specimen. This is equivalent to that produced by a microscope having the impossible combination of a high-NA objective lens and an infinite depth of focus. A variation on this method allows efficient calculation of stereo pairs.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1982

Detection of glomerular bleeding by phase-contrast microscopy.

Midstream urine specimens from 303 consecutive patients with haematuria were examined with phase-contrast microscopy to determine whether the source of the haematuria could be predicted on the basis of urinary red-cell morphology. In 253 patients a definite diagnosis was made but the data for the other 50 were inadequate to allow a definite diagnosis. With phase-contrast microscopy the origin of haematuria was considered to be glomerular in 120 patients (115 had proven glomerulonephritis and 5 had lesions of the lower urinary tract) and non-glomerular in 105 patients (100 had lesions of the lower urinary tract and 5 had proven glomerulonephritis). A mixed picture of glomerular and non-glomerular red cells was seen in 28 patients, most commonly in association with IgA nephropathy and renal calculi. The assessment of urinary red-cell morphology by means of phase-contrast microscopy can add importantly to clinical information and, together with the presence of red-cell casts and protein in the urine, can help the clinician decide on initial investigations in patients with haematuria.

Erythrocytes↗
PubMed1993

Macrocyclization of polysaccharides visualized by electron microscopy.

Topological features of the polysaccharides schizophyllan, l-carrageenan and gellan gum were studied using electron microscopy. Electron micrographs of schizophyllan not subjected to any thermal or solvent composition history destabilizing the triple helix, show stiff, linear chains consistent with the structure being triple helical and with contour length proportional to the molecular weight in solution. A blend of linear, cyclic and hairpin topologies and higher molecular weight clusters were observed after renaturation, i.e. return to conditions favouring the triple helical structure, from solvent conditions dissociating the triple helix. Electron micrographs of l-carrageenan in salt-free solution reveal linear extended structures. Addition of 0.15 M LiI to the solution before preparation for electron microscopy, i.e. salt conditions that favour ordering but not gelation, yields a large fraction of cyclic structures with circumference of different lengths. Likewise, adding KCl to aqueous gellan gum changes their appearance from dispersed polymers to suprastrands with several associated chains. Macrocyclic species can also be observed in gellan gum after the addition of a gel-promoting salt. The tendency to form macrocyclic structures in competition with intermolecular aggregates is determined by the three factors: (1) chain stiffness relative to overall length; (2) parallel or antiparallel alignment of interacting chain segments; and (3) polymer concentration. The present study indicates that electron microscopy provides information about the topology adopted by polysaccharides.

Carbohydrate Conformation↗
PubMed2001

Evaluation of corneal stromal changes in vivo after laser in situ keratomileusis with confocal microscopy.

PURPOSE: To assess by in vivo confocal microscopy the modifications of the corneal stroma after laser in situ keratomileusis (LASIK) for myopia. DESIGN: Nonrandomized comparative (self-controlled) trial. PARTICIPANTS: Sixteen eyes of 13 patients were examined before surgery and at days 8, 30, and 90, and 9 eyes were examined at 6 months postoperatively using an in vivo confocal microscope. TESTING/INTERVENTION: Stromal morphologic changes, keratocyte density, flap thickness, and subclinical haze were evaluated and compared at different time points. LASIK was performed with a Flapmaker microkeratome (Solan Ophthalmic products, Jacksonville, FL) and a Lasersight LSX excimer laser (LaserSight Technologies Inc., Winter Park, FL). MAIN OUTCOME MEASURE: Confocal microscopy results. RESULTS: Microfolds at the Bowman's layer were found in most eyes, as well as variable reflectivity particles (pa) located at the interface level in all eyes examined postoperatively. The density of these particles significantly decreased with time with, respectively, 504 +/- 101 pa/mm2 at day 8 and 380 +/- 111 pa/mm2 at day 30 (P = 0.003), 332 +/- 100 pa/mm2 at month 3 and 312 +/- 40 pa/mm2 at month 6. The mean flap and the activated-cells area thicknesses were, respectively, 102 +/- 26 microm and 61 +/- 19 microm and showed significant negative correlation (P < 0.0001). The intensity of the added peak (47.3 microm 8.6%), corresponding to the subclinical haze, realized by Z-scan measure, was also negatively correlated with flap thickness (P = 0.01). Keratocyte (k) density quantified in the posterior stroma significantly increased from day 0 (480 +/- 67 k/mm2) to day 8 (701 +/- 41 k/mm2, P < 0.0001 compared with day 0) and day 30 (917 +/- 143 k/mm2, P = 0.0006, compared with day 0) but significantly decreased at 3 months postoperatively (597 +/- 56 k/mm2, P < 0.0001 compared with day 30) to reach the initial level at month 6 (502 +/- 41 k/mm2, nonsignificant compared with day 0). There was no correlation between preoperative or postoperative spherical equivalent and the density of particles, keratocytes, and the haze intensity. CONCLUSIONS: This study confirms the presence of microfolds and particles at the interface level, as well as subclinical impairment. Evaluation of keratocyte density constitutes a major contribution of confocal microscopy toward an understanding of the keratocyte response to corneal wound healing after corneal refractive surgery. Moreover, flap thickness seems to be involved in the postoperative cellular activation with a higher response when thin.

Adult↗
PubMed1981

Electron microscopy for the diagnosis of ocular viral infections.

Tear samples obtained from patients with suspected viral conjunctivitis were examined by virus culture and by the pseudoreplica method for electron microscopy (EM). Adenoviruses were isolated in 13 of the 34 cases (38%) clinically diagnosed as adenovirus conjunctivitis. Characteristic adenoviral particles were demonstrated by electron microscopy in seven of the culture-positive, and two of the culture-negative samples. In cases of herpes simplex virus ocular infection, tears were virus positive by culture in one-third of the patients; two-thirds of the culture positive specimens were also positive by EM. This study demonstrates the potential of electron microscopy as a rapid, specific, and relatively inexpensive method for the laboratory diagnosis of ocular viral infections.

Adenoviridae Infections↗
PubMed1997

Quantification of stromal thinning, epithelial thickness, and corneal haze after photorefractive keratectomy using in vivo confocal microscopy.

PURPOSE: The authors establish, for the first time, observer-independent quantification of stromal thinning, epithelial thickness, and corneal haze after excimer laser photorefractive keratectomy (PRK) using a unique, new form of in vivo confocal microscopy. METHODS: Rapid, continuous z-scans of high-resolution confocal images, termed confocal microscopy through focusing (CMTF), were performed in the central corneal area of 17 patients before and 1 month after PRK for low- to moderate-grade myopia (-2.88-9.13 diopters [D]). Corneal, epithelial, and stromal thickness measurements and an objective haze estimate were obtained from each CMTF scan by digital image analysis. RESULTS: Epithelial thickness averaged 51 +/- 4 microns before and 45 +/- 10 microns 1 month post-PRK (P < 0.005), whereas stromal thinning ranged from 20 to 154 microns, representing a direct estimate of the actual photoablation depth. Corneal thickness averaged 560 +/- 36 microns before PRK and 462 +/- 52 microns at 1 month. The change in corneal thickness correlated closely with the change in spherical equivalent refraction (r = 0.94, P < 0.0001); linear regression analysis revealed a value of 14.3 microns corneal thinning per diopter of correction. A significant correlation was found between the objective CMTF haze estimate and a clinical haze grading obtained by slit-lamp examination (r = 0.73, P < 0.001). CONCLUSIONS: Confocal microscopy through focusing is a new, powerful in vivo tool that enables quantitative, unbiased evaluation of PRK procedures over time by providing epithelial and stromal thickness analysis, photoablation depth assessment, and unbiased haze measurement. The method is uniquely valuable in the pre- and postoperative assessment of PRK patients and for determining the optimal treatment strategy, especially in assessing refractive and visual outcomes in individual cases.

Adult↗
PubMed1998

Microscopy and latex antigen negative cryptococcal meningitis.

A HIV-positive patient presented with cryptococcal meningitis that was not detected by cerebrospinal fluid (CSF) latex antigen and direct microscopy. The diagnosis was confirmed by culture of the CSF and subsequent urine culture, both of which yielded an apparently acapsular strain of Cryptococcus neoformans. After 19 months the patient relapsed and capsulated yeasts were observed on this occasion on direct microscopy of the CSF. The latex antigen test was strongly positive. Culture again yielded an apparently acapsular isolate. Retrospective culture of all isolates obtained from this patient in sterile CSF resulted in the formation of capsules. This was confirmed by the requirement of normal non heat inactivated serum for neutrophil-cryptococcus attachment to occur in vitro. Although antigen and direct microscopy are frequently relied upon to diagnose cryptococcal meningitis, a negative result does not exclude the condition.

AIDS-Related Opportunistic Infections↗
PubMed2002

Visualization of individual axons in excised lamprey spinal cord by magnetic resonance microscopy.

The direct visualization of axons within their native tissue environment by magnetic resonance (MR) microscopy is presented for the first time in the excised larval sea lamprey spinal cord. A home-built transverse radio frequency coil of 1.5 mm diameter was used in conjunction with a commercial 400 MHz MR microscopy system, implementing both 2-D and 3-D imaging pulse sequences. Images having nominal voxel sizes of 9x9x500 and 9x9x125 microm(3), respectively, in the lamprey spinal cord were obtained, resolving individual Mauthner and Müller axons. Furthermore, architectural changes associated with axonal degeneration were visualized in the spinal cord of one animal, excised 8 weeks after hemisection of the cord. Although the lamprey previously has not been the subject of MR microscopy investigations, these results demonstrate the method's potential for imaging this axon system, which is an important model of spinal cord injury and regeneration.

Animals↗
PubMed1993

The anterograde neuroanatomical tracer biotinylated dextran-amine: comparison with the tracer Phaseolus vulgaris-leucoagglutinin in preparations for electron microscopy.

We investigated the properties of biotinylated dextran-amine (BDA) as a neuroanatomical tracer at the electron microscopic level and we compared the results with those obtained previously with another tracer, the lectin Phaseolus vulgaris-leucoagglutinin (PHA-L). BDA was injected into various brain areas of rats. Following survival and fixation, vibratome sections were cut, subjected to a freeze-thaw treatment, and incubated overnight with avidin-biotin complex (ABC). Following reaction with diaminobenzidine (DAB)-hydrogen peroxide, the sections were processed for electron microscopy. In the electron microscope we observed that the reaction product occurred in the cytoplasm of cell bodies and in the matrices of dendrites, axons and axon terminals following ABC histochemistry of BDA-containing brain sections. The ultrastructural details of BDA-labelled neurones were generally better preserved than in PHA-L-labelled material, whereas at the same time penetration of the reagent into the sections was complete (incomplete in sections of PHA-L material). We conclude that the use of BDA as a neuroanatomical tracer in electron microscopy is a good substitute for PHA-L. The detection method for transported BDA is much faster and less complicated than that for PHA-L, while the results are better; that is, there is improved penetration coinciding with good preservation of ultrastructure. Keeping the limitations of BDA as a neuroanatomical tracer in mind, e.g., retrograde transport into local collaterals of axons that intermingle with anterogradely labelled axons, BDA seems well suited as a neuroanatomical tracer for electron microscopy.

3,3'-Diaminobenzidine↗