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At least 973 records · Page 54Linked to original sources
PubMed1989

Isolation of large sheets of apical material from frog urinary bladder epithelial cells by freeze-fracture.

In the amphibian urinary bladder, water permeability is correlated with the insertion of intramembrane particle aggregates (IMPAs) into the apical plasma membrane (AM) of the granular cells. These aggregates are believed to contain water channels. Characterization of the IMPAs by comparing AM fractions of antidiuretic hormone (ADH)-treated and resting epithelia requires isolation and purification of AM-rich material, free of other cytoplasmic aggregate-containing organelles, in both cases. A technique derived from freeze-fracture was chosen to isolate large sheets of apical membrane material from frog (Rana esculenta) urinary bladder epithelium. The apical side was plated on a polylysine-coated glass slide, frozen with liquid nitrogen, and fractured. A nylon mesh was inserted between the glass slide and the bladder, in order to bring the fracture plane back to the AM periodically. Fluorescent markers were used to characterize the material having fractured with the glass slide. Samples were observed by fluorescence and phase contrast microscopy. We obtained evidence that numerous patches of fractured AM remained on the glass surface without nuclei. A phase contrast picture was obtained only at a high magnification, indicating a low thickness of the recovered material. Further characterization was made with SDS-PAGE. Protein contents of samples were extracted under various experimental conditions and the patterns of ADH-treated, resting AM samples, or whole epithelial cell crude homogenates, were compared. Staining of some bands increased under certain conditions, whereas many others disappeared. Both morphological and biochemical approaches demonstrate that the recovered material was apical in origin.

Animals↗
PubMed1997

Diagnosis of glomerular haematuria: role of dysmorphic red cell, G1 cell and bright-field microscopy.

Differentiation between glomerular and non-glomerular haematuria by observation of the changes in red cell morphology using phase-contrast microscopy is a well established technique. However, the method is not widely accepted in clinical practice because of controversy regarding the minimum percentage of dysmorphic red cells required to diagnose glomerular aetiology, as well as the need for specialized microscopes. Recently, a glomerular-specific morphological alteration of red cells has been described, which has the form of a doughnut shape with one or more blebs and which is termed the "G1" cell. In the present double-blind prospective study 250 urine samples were examined without any knowledge of diagnosis. Haematuria was detected in 122 cases. The type of haematuria was characterized by counting dysmorphic cells and G1 cells separately, in each case using a phase-contrast microscope as well as an ordinary bright-field microscope with and without staining of urinary sediments. The results were later correlated with the confirmed diagnosis. The study showed that the G1 cell is more specific than the dysmorphic cell for the diagnosis of glomerular haematuria. Evaluation of both dysmorphic red cells and G1 cells can be done using bright-field microscopy with 100% specificity and sensitivities of 82 and 100%, respectively. It has been concluded that the ordinary bright-field microscope can be used for the diagnosis of glomerular haematuria with an efficiency similar to that of a phase-contrast microscope.

Adolescent↗
PubMed1989

Dysmorphism of urinary red blood cells--value in diagnosis.

To aid investigation into the clinical problem of hematuria, assessment of abnormalities in the shape of red cells in the urine (dysmorphism) is gaining popularity in nephrology. However, there is uncertainty in the literature regarding both the number of red blood cells (RBC) in normal urine, as well as the quantification of dysmorphism. We have shown that in normal urine (N = 27) the number of RBC is less than 2,000/ml as assessed by scanning electron microscopy of filtered urine specimens from normal volunteers without known renal disease, which compared to less than 1,000/ml by centrifugation and phase contrast microscopy of the same specimen. To determine whether dysmorphism of urinary red blood cells was a significant predictor of glomerular disease we compared the number of dysmorphic cells in the urine of patients with biopsy proven glomerulonephritis (GN), before and immediately after renal biopsy. We also compared the number of dysmorphic cells in patients with glomerulonephritis to those with lower urinary tract bleeding. Renal biopsy caused significant dysmorphic hematuria, indicating that dysmorphism suggests renal rather than glomerular bleeding. Although patients with GN had significantly more dysmorphic urinary RBC when compared to those with lower tract urinary bleeding, the overlap was such that one could only be confident of renal hematuria if they accounted for greater than 75% of the total number of RBC. Non renal hematuria is present if number of dysmorphic cells is less than 17% of total RBC. Thus dysmorphism of urinary RBC is a useful diagnostic tool, but only if strict criteria established for each laboratory are adhered to.

Erythrocyte Count↗
PubMed1991

In vitro bone resorption by isolated multinucleated giant cells from giant cell tumour of bone: light and electron microscopic study.

The behaviour of multinucleated giant cells (GCs), obtained from a giant cell tumour of the tibia and cultured on glass coverslips or on devitalized bone slices, was studied using light and electron microscopy. Monitoring the GCs on bone slices by phase-contrast microscopy revealed that they had removed calcified bone matrix resulting in excavation of lacunae, with subsequent lateral extension and perforation of the bone slices. Electron microscopy demonstrated for the first time that the GCs responsible for exavating lacunae had two specific membrane modifications, ruffled border and clear zone, and showed basically similar cytoplasmic fine structures to those of osteoclasts. Fluorescence images of the GCs on glass and on bone after rhodamine-conjugated phalloidin staining revealed that most of the GCs had an intensely fluorescent peripheral band composed of a number of F-actin dots called podosomes. Some GCs showed unusual arrangements of podosomes suggesting abortive attempts at GC formation. We have demonstrated that the band structure of the GCs cultured on bone is intimately involved in bone resorption. Two stromal cell types could be recognized. The predominant type, which seemed to be the only neoplastic element because of its proliferative capability, showed quite different fine structural and cytoskeletal features from the GCs. The other type, which was much less frequent and seemed not to proliferate, had morphological similarities to the GCs, and seemed to be their precursor. Importantly GCs cultured on bone and the osteoclasts share common structures for adhesion to and resorption of bone, strongly supporting the view that the GCs of the giant cell tumour of bone are potentially active bone resorbers and can be regarded as osteoclasts.

Adult↗
PubMed1980

Changes in cell diameter during the division cycle of Escherichia coli.

Extensive measurements of steady-state populations of several Escherichia coli strains have consistently indicated that cell diameter decreases with increasing cell length. This was observed both after electron microscopy of air-dried cells and after phase-contrast microscopy of living cells. The analysis was made by considering separately the unconstricted cells and three classes (slight, medium, and deep) of constricted cells in the population. During slow growth, cells with the average newborn length were up to 8% thicker than unconstricted cells twice as long. This decrease in diameter is less at higher growth rates. Despite the small changes and the large variation of the diameter in any particular length class, significant negative correlations between diameter and length were obtained. Cell diameter increases again at the end of the cell cycle as indicated by an increase of average diameter in the three consecutive classes of constriction.

Bacillus subtilis↗
PubMed1984

Development of a mathematical model for predicting concentrations of small asbestos fibers.

The standard method of asbestos sample analysis by phase-contrast microscopy excludes fibers which are below the resolution limits of the light microscope. Electron microscopic studies revealed that fibers in these small size ranges comprise the majority of fibers in asbestos dust. This research was conducted to determine if the development of a mathematical model for predicting concentrations of small fibers (less than 5 microns length) based on phase-contrast concentrations was feasible. The model presented in this paper was evaluated for its practical utility and was determined to be of minimal value; however, it was felt that the development of a reasonably accurate model can be arrived at through continued research.

Asbestos↗
PubMed1986

Movements and other distinguishing features of small vesicles identified by darkfield microscopy in living macrophages.

Perinuclear vesicles (estimated diameter less than 0.15 micron), too small to be seen in living mouse macrophages by direct phase-contrast microscopy, could be detected by darkfield microscopy thanks to their rapid non-saltatory movements at 37 degrees C, contrasting with the slower saltations of accompanying phase-visible larger vesicles (0.25-0.5 micron, presumed secondary lysosomes). The movements of these 'small visicles' also differed from those of the 'larger visicles' in their responses to changes in temperature, and to chemical agents known to inhibit both the saltations of secondary lysosomes and the latter's fusion with phagosomes. Thus the 'larger vesicles' stopped moving at 25 degrees C, the small ones did not; both stopped at 18 degrees C. The 'small vesicles' continued to move actively after cell uptake of the polyanion poly-D-glutamic acid, while the saltations of the 'larger vesicles' were markedly slowed; both sets of vesicles stopped after uptake of ammonium chloride. Degranulation of the small vesicles paralleled that of the larger, while simultaneously observed preformed pinosomes (labelled with fluorescent wheat germ agglutinin (WGA) appeared to be unaffected. On the basis also of refractivity, location and speed the 'small vesicles' are considered not to be pinosomes, but probably to be lysosomes. The question of whether they are a subgroup of small immature secondary lysosomes or primary lysosomes (0.05-0.08 micron) is discussed. The broad spectrum of movement inhibited by ammonia in macrophages raises the possibility that this weak base inhibits movements of all lysosomes. Further characterization of these 'small vesicles' requires their relation to be defined to the small particles in other cell types (especially in axoplasm) which have been detected by video-enhanced microscopy.

Ammonium Chloride↗
PubMed1984

An evaluation of the precision and accuracy of the direct transfer method for the analysis of asbestos fibers with comparison to the NIOSH method.

Transmission electron microscopy (TEM) of asbestos on polycarbonate membrane filters prepared using the direct transfer (DT) method is used as a reference for determining the precision and accuracy of phase contrast microscopy (PCM) of the same filters and for determining the correlation between DT-PCM and the NIOSH method of asbestos analysis. Replicate aliquots of an aqueous suspension of chrysotile were filtered through either polycarbonate or cellulosic membrane filters. The polycarbonate filters were prepared using the DT method and analyzed using TEM and PCM; the cellulosic filters were treated and analyzed using the NIOSH method. Compared to the results of the TEM examination of the polycarbonate filters, about 50% of the fibers longer than 5 micron were detected using DT-PCM, which was more than 3 times the result obtained using the NIOSH method. The improvement in accuracy using DT-PCM is attributed to the increased visibility of thin fibers (diameters less than 0.1 micron). The largest variation in results was found to be due to the fiber distribution on the filters. This factor may be eliminated from interlaboratory comparisons, etc. by the use of pre-designated and well-defined fields-of-view.

Asbestos↗
PubMed1982

Dome formation by oral epithelia in vitro.

Multicellular, cystic structures, termed domes, have been described previously in epithelia cultured from various tissues that have a known transport or secretory function in vivo and in vitro. We report for the first time dome formation in cells cultured from "covering" and "rest" epithelia of oral tissues: porcine gingival and alveolar mucosa epithelium and epithelial rests of Malassez. As demonstrated by light- and electron microscopy, the morphology of the domes varied with the location of their lumen and the number of cells or cell layers involved in their structure. Sequential observations using phase contrast microscopy and time lapse cinematography of living cultures showed that the domes were dynamic structures with expansion-collapse cycles of between 30 min and 17 h duration. Dome formation in oral epithelia was stimulated by dibutyryl cyclic AMP (dbcAMP, 10(-3) to 10(-6) M) and abolished by ouabain (10(-10) M), an inhibitor of sodium transport. The morphological features and the dynamic nature of domes found in oral epithelia, and their dbcAMP and ouabain responsiveness are similar to those demonstrated previously in several other epithelia that have a known transport function in vivo and in vitro. Such fluid transport is not thought to be a property of oral epithelia in vivo. Our data, however, suggest a similar function of these epithelia cultured in vitro, and perhaps in pathological cyst formation in vivo.

Animals↗
PubMed1988

Autonomic receptor characterization in cultured adult rat cardiac myocytes: morphologic-functional correlation.

Adult calcium tolerant rat ventricular myocytes were maintained under serum-free culture conditions for five days. beta-adrenergic and muscarinic cholinergic receptor expression was assessed by radioligand binding determinations using 125I-iodocyanopindolol (ICYP) and [3H]-quinuclidinyl benzilate (QNB), respectively. The binding data were correlated with myocyte structural integrity and contractile responsiveness to norepinephrine (NE). During the 5 days in primary culture, beta-adrenergic and muscarinic cholinergic receptor binding capacity diminished Bmax = 17.1 to 9.2 fmol/mg protein and Bmax = 169.0 to 26.6 fmol/mg protein, respectively. The affinity of both autonomic receptors was unaltered during the period of observation. The majority of isolated myocytes were viable (65 to 85%) and remained rod-shaped for 5 days as assessed by phase contrast microscopy. Up to 2 days in vitro the rod-shaped myocytes appeared ultrastructurally similar to their in vivo counterparts and displayed intact nuclei and the usual complement of cellular organelles. From day 3, phase contrast as well as transmission electron microscopy revealed a progressive increase in autophagic vacuoles consisting primarily of disrupted mitochondria. The number of myocytes that contracted in response to norepinephrine (NE) decreased from 57.2 to 2.3% by day 5. These data indicate that adult rat cardiac myocytes maintained in serum free culture for 5 days, express beta-adrenergic and muscarinic cholinergic receptors. There is a rapid decline (50%) in muscarinic cholinergic receptor number and contractile response to NE by day 2. However, the decrease in beta-receptor Bmax by day two is insufficient to explain the severe loss of cell responsiveness to NE. This functional loss may be related, at least in part, to the ultrastructural abnormalities that are first evident at day 2 in culture. Thus, short-term myocyte cultures that retain phenotypic and physiologic characteristics of in vivo cardiac myocytes could provide a useful in vitro system for exploring pharmacologic-functional interactions in the myocardium.

Animals↗
PubMed1987

Salt and peroxide compared with conventional oral hygiene. I. Clinical results.

The purposes of this 2-year longitudinal study were to: compare the clinical effectiveness of patient applied sodium bicarbonate, hydrogen peroxide, and sodium chloride (S/P) to the use of conventional oral hygiene methods and to investigate the motivational effect of using phase-contrast microscopy in teaching effective oral hygiene. Initially, 972 subjects were screened for signs of periodontitis. From these, 347 with early to moderate periodontitis were selected and each was randomly assigned to one of four home treatment regimens after scaling and root planing. The four treatment regimens included: conventional oral hygiene procedures, conventional oral hygiene procedures plus phase-contrast demonstration of subgingival microbial forms for oral hygiene motivation, S/P oral hygiene, and S/P oral hygiene plus phase-contrast demonstration of subgingival microbial forms for oral hygiene motivation. Plaque, bleeding, gingival inflammation, probing depth, and clinical attachment level were recorded at baseline, 8, 16, and 24 months. Subjects were recalled for reinforcement of oral hygiene and periodontal prophylaxis at various intervals. Data were analyzed based on disease severity, location of index sites and compliance. The results indicated that both conventional oral hygiene procedures and the S/P regimen were effective in reducing clinical signs of disease when combined with professional care. There were no differences between the two regimens in clinical effectiveness and trends favoring microscopic viewing of subgingival plaque for motivational purposes were not statistically significant.

Adult↗
PubMed1976

Cytoplasmic inheritance in Saccharomyces cerevisiae: comparison of zygotic mitochondrial inheritance patterns.

Mitochondrial movements in Saccharomyces cerevisiae (Sc) zygotes were monitored with phase-contrast microscopy and compared to known mitochondrial inheritance systems. The mitochondria of Sc were convincingly identified by integrated use of phase-contrast, cytochemical and electron microscopic observations. Mitochondria in Sc appear to move by saltatory jumps, which appear to be oriented towards movement of mitochondria into developing buds. Tracking of mitochondria of different genotypes was made possible by positive identification of each mitochondrial population before zygosis, and by the low degree of mixing (less than 10%) of mitochondrial populations before first bud septation. A grande by grande cross demonstrated equal numbers of mitochondria from each haploid moving into the first zygotic bud. A grande by neutral petite cross gave a 2:1 ratio of grande to petite mitochondria. However, a grande by suppressive petite cross gave equal numbers of grande and petite mitochondria. Using drug resistance systems, a comparison was made of highly biased (97%) and moderately biased (71%) chloramphenicol resistant inheritance patterns. In both cases, the ratios of drug resistant to sensitive mitochondria were 1:1. When numbers of mitochondria moving into an individual bud were compared to the phenotypic content of the clone of that bud, no model could be constructed which could predict the latter from the former. The data indicate (with the exception of the neutral petite by grande cross) that the numbers of each mitochondrial type "inserted" into the first zygotic bud are equal, regardless of the degree of asymmetry of inheritance of mitochondrial markers.

Chloramphenicol↗
PubMed1999

Cycloheximide and 4-OH-TEMPO suppress chloramphenicol-induced apoptosis in RL-34 cells via the suppression of the formation of megamitochondria.

Toxic effects of chloramphenicol, an antibiotic inhibitor of mitochondrial protein synthesis, on rat liver derived RL-34 cell line were completely blocked by a combined treatment with substances endowed with direct or indirect antioxidant properties. A stable, nitroxide free radical scavenger, 4-hydroxy-2,2,6, 6-tetramethylpiperidine-1-oxyl, and a protein synthesis inhibitor, cycloheximide, suppressed in a similar manner the following manifestations of the chloramphenicol cytotoxicity: (1) Oxidative stress state as evidenced by FACS analysis of cells loaded with carboxy-dichlorodihydrofluorescein diacetate and Mito Tracker CMTH2MRos; (2) megamitochondria formation detected by staining of mitochondria with MitoTracker CMXRos under a laser confocal microscopy and electron microscopy; (3) apoptotic changes of the cell detected by the phase contrast microscopy, DNA laddering analysis and cell cycle analysis. Since increases of ROS generation in chloramphenicol-treated cells were the first sign of the chloramphenicol toxicity, we assume that oxidative stress state is a mediator of above described alternations of RL-34 cells including MG formation. Pretreatment of cells with cycloheximide or 4-hydroxy-2,2, 6,6-tetramethylpiperidine-1-oxyl, which is known to be localized into mitochondria, inhibited the megamitochondria formation and succeeding apoptotic changes of the cell. Protective effects of cycloheximide, which enhances the expression of Bcl-2 protein, may further confirm our hypothesis that the megamitochondria formation is a cellular response to an increased ROS generation and raise a possibility that antiapoptotic action of the drug is exerted via the protection of the mitochondria functions.

Animals↗
PubMed2003

Sperm ultrastructure and spermatogenesis in the lizard, Tropidurus itambere.

Spermatogenesis, with emphasis on spermiogenesis, is described for the lizard, Tropidurus itambere, using light microscopy, phase contrast and epifluorescence, as well as scanning and transmission electron microscopy. Cellular differentiation involves events of chromatin condensation, nuclear elongation and the formation of structural complexes, such as the acrosomal and axonemal ones. Other new characteristics, exclusive for this species, include various aspects of the subacrosomal granule, the insertion of the pro-acrosomal vesicle and the development of these structures to participate in the acrosomal complex. Radial projections occurjust above the nuclear shoulders, which have been recognized already from the beginning of cellular elongation. The development of the midpiece, the dense bodies, formation of the flagellum and elimination of residual cytoplasm result in the final characterization of the mature spermatozoon. Comparisons between Tropiduridae and other lizard families are made.

Acrosome↗
PubMed1986

Comparison of the results of asbestos fibre dust counts in lung tissue obtained by analytical electron microscopy and light microscopy.

The efficiency of the light microscope with that of the electron microscope in detecting asbestos fibres in human lung tissue was computed. Necropsy material from 55 patients who had died from asbestos related diseases was analysed independently by phase contrast microscopy and electron microscopy. As expected the number of fibres identified using electron microscopy was higher than that identified by light microscopy. By adjusting the electron allow for the limited resolving power of the light microscope, however, a significant correlation of the number of fibres identified using the two methods was obtained. The best correlation was found with specimens containing crocidolite (correlation coefficient 0.79) and amosite (correlation coefficient 0.74), while chrysotile gave a much lower correlation (correlation coefficient 0.15). The cumulated fibre diameter distribution obtained using the electron microscope suggests that the light microscope is able to visualise only 5% of crocidolite, 26.5% of amosite, and 0.14% of chrysotile present in lung tissue. Therefore, although it is possible, using the electron microscope, to predict the asbestos fibre count that would be obtained by light microscopy, the reserve prediction cannot be made: it is impossible to determine the proportion of the various asbestos mineral types using the light microscope.

Asbestos↗