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At least 415 records · Page 23Linked to original sources
PubMed2003

Comparison of two direct-reading instruments (FM-7400 and Fibrecheck FC-2) with phase contrast optical microscopy to measure the airborne fibre number concentration.

The use of direct-reading instruments to measure the airborne fibre number concentration is on the increase. The response of two of these instruments (FM-7400 and Fibrecheck FC-2) was compared with the conventional method of sampling on filters and counting by phase contrast microscopy. Four types of fibres were studied at different concentrations and relative humidity levels. The FM-7400 can be calibrated by the manufacturer for two different levels of sensitivity (standard and high). For the tests where it was set to the sensitivity level with which it had been calibrated, the ratio of the concentration measured by the instrument to the concentration obtained by the conventional method varied in the range 0.5-1 for the different types of fibres studied (chrysotile, glass wool and ceramic fibres). The Fibrecheck FC-2 is a much less versatile instrument. On the basis of a calibration allowing correct detection of asbestos fibres, it greatly overestimated the concentration of man-made mineral fibres. In its normal calibration state a fine chrysotile aerosol was poorly detected. For man-made mineral fibres, the response was highly dependent on the nature of the fibres. These instruments require calibration with the type of fibres to be studied. Unfortunately, this operation is not always accessible to the user and may require the services of a specialized laboratory, as the manufacturer is not always in a position to carry this out.

Aerosols↗
PubMed1995

Effect of artificial tears on cultured keratocytes in vitro.

We investigated the effects of artificial tears on cultured rabbit and human keratocytes in vitro. The cells were exposed to seven nonpreserved commercially available artificial tear formulations and examined under phase-contrast microscopy for 60 min. After 5-min exposures to the solutions, rabbit keratocytes were fixed for transmission electron microscopy (TEM). In rabbit keratocytes, phase-contrast microscopy and TEM demonstrated that Aqua Site (CIBA Vision Ophthalmics, Atlanta, GA, U.S.A.), Hypo Tears PF (Johnson & Johnson, Claremont, CA, U.S.A.), and Tears Naturale Free (Alcon, Humacao, Puerto Rico, U.S.A.) immediately induced intracytoplasmic vacuoles and cell swelling, and subsequent cell degeneration. Rabbit cells exposed to the other artificial tears, which contained Ca2+ and did not contain EDTA, maintained their normal shape and appearance for 60 min. Phase-contrast microscopy of human keratocytes showed that Aqua Site and Hypo Tears PF induced mild and delayed cellular swelling, but the other artificial tears tested did not affect the cell shape for the entire 60-min observation period. Electrolyte balance and osmolarity of artificial tears appear to be critical for keratocyte survival. Maintenance of keratocyte integrity may be an important factor to consider when selecting an artificial tear preparation to be used when corneal epithelium is not intact.

Animals↗
PubMed1987

A rapid screening technique for the detection of spermatozoa.

Phase contrast microscopy has been used for some time to search for and identify spermatozoa. An enhancement to the technique using xylene in conjuction with phase contrast microscopy is discussed. The method has been found to save time by allowing identification of spermatozoa with xylene-enhanced phase contrast microscopy in many cases that would have been unsuccessful using the normal "dry" phase contrast microscopy techniques. This eliminates a staining and reexamination step.

Humans↗
PubMed2006

A rheological method to evaluate the physical stability of highly viscous pharmaceutical oil-in-water emulsions.

PURPOSE: The aim of this study was to develop a rheological method to evaluate the stability of highly viscous pharmaceutical emulsions. Thereby, the time devoted to the storage tests could be reduced and manufacturers could save time in optimizing their formulations and manufacturing techniques for topical pharmaceutical forms. The influence of the type of oil and the type of emulsifier on the microstructure of the emulsions was also studied. MATERIALS AND METHODS: The samples were stored at 25 and at 50 degrees C for 6 months and analysed every month using rheological as well as microscopic techniques. The size and the organization of the droplets within the emulsion were determined by freeze-fracture electron microscopy and optical contrast phase microscopy. RESULTS: A decrease in the rheological parameters was observed for the OC emulsions ("Tween/Span" emulsions made with olive oil) and the "Montanov" emulsions. The rheological measurements showed that the structure of the OC emulsions and that of the emulsions made with the Montanov 82 emulsifier become more brittle when submitted to a shear force. The micrographs obtained by freeze-fracture electron microscopy showed that for OC only the oil droplets arrange in a network structure. Storage tests at 50 degrees C confirmed the rheological assumptions on the stability of emulsions. CONCLUSION: The study of the effect of shearing on the emulsions allowed quick discrimination between the emulsions according to their stabilities. The rheological tool gave information on the structure of the emulsions and on the aging process.

Administration, Topical↗
PubMed1967

Isolation of cell nuclei from the mammalian cerebral cortex and their assortment on a morphological basis.

An aqueous method is described for the isolation of highly purified nuclei from the cerebral cortex of adult guinea pigs. Erythrocytes were removed by a short-time perfusion of the brain, myelin fragments by a rapid mechanical method, and blood capillaries by a centrifugal sieving through dense sucrose solutions. The nuclear preparation retained the activity of ATP:NMN adenylyltransferase. Recoveries of DNA in the P4I, P4II, P(L) and P(S) preparations were 30, 43, 8, and 7%, respectively. Microscopy and phase contrast microscopy showed a satisfactory removal of erythrocytes, myelin fragments, capillaries, and cytoplasmic elements. Biochemical purity of samples was verified by the absence of several cytoplasmic enzyme activities. In the electron microscope, the majority of nuclei showed well-preserved nuclear membranes, with nuclear pores, and were provided with a finely textured nucleoplasm. Occasional contaminants were elements of endoplasmic reticulum and of the endothelium. Assortment of nuclei on a morphological basis showed that 55-65% and 47-53% of nuclei in the P4I and P4II preparations, respectively, consisted of neuronal nuclei. In the P(L) preparation, the population of neuronal nuclei ranged between 72 and 83%, while 94-99% of the nuclei in the P(S) preparation consisted of smaller nuclei, most likely of oligodendroglial origin.

Acetylcholinesterase↗
PubMed1996

Exposure to asbestos fibres during gasket removal.

In the chemical industry, asbestos gaskets have been used extensively to prevent leakage between solid surfaces. The purpose of this study was to assess the potential personal exposure to asbestos fibres during gasket removal and thus to determine what is reasonably required in terms of protective regime and work method. Two groups were studied: group A, who only removed gaskets if they could be removed easily and without breaking; and group B, who removed gaskets which were left by the first group. For both groups, the gasket was first made wet before removal. The samples were analysed using phase-contrast microscopy and transmission electron microscopy. The average exposure to fibres for group A, averaged over the work period, was 0.04-0.242 fibres ml-1 as determined by phase-contrast microscopy. On further analysis with transmission electron microscopy it was found that only four of the 11 samples contained asbestos in very low concentrations and that most of the fibres, which were identified using phase-contrast microscopy, probably originated from the glass fibre lagging around the pipes. For group B the average fibre concentration, averaged over the work period, as determined by phase-contrast microscopy, ranged between below the detection limit and 0.02 fibres ml-1. The subsequent transmission electron microscopy analysis shows that the exposure to asbestos fibres ranged between below the limit of detection to 0.004 fibres ml-1. This study shows that the exposure to asbestos fibres during gasket removal activities was well within the 8-h average exposure limit of 0.3 fibres ml-1.

Asbestos↗
PubMed1995

Phase contrast microscopic evaluation of placental pathology in premature gestation.

Numerous representative samples taken from forty placentas immediately after delivery from mothers associated with prematurity (i.e. less than 38 weeks), were semiquantitatively studied by phase contrast microscopy. Twenty placentas delivered from mothers without any antenatal complication served as control. Hypoplasia of the syncytium, stromal edema, ischaemia were prominent findings on phase contrast microscopy in the study group. Increased basement membrane thickening and high villous edema scores observed on light microscopy were statistically significant in prematurity as compared to controls. Observations by phase contrast and light microscopy were found complementary to each other. Phase contrast microscopy provided quicker results without disadvantage of fixation artefact and was found distinctly superior over the conventional histological methods.

Case-Control Studies↗
PubMed1994

Urinary red cell morphology to detect site of hematuria.

We studied the urinary RBC morphology in 87 consecutive cases of significant hematuria by 3 commonly used methods: (a) light microscopy of the unstained urinary sediment; (b) phase contrast microscopy of the unstained urinary sediment; and (c) Wright's staining of the urinary sediment, in order to compare the sensitivity of these methods in detecting dysmorphic RBCs and thus predicting the site of hematuria. The clinical data and the relevant investigations were made available after the morphology of RBCs in the urine was identified. Out of the 87 patients, 45 had a glomerular and 42 had a nonglomerular cause o hematuria. Phase contrast microscopy showed a sensitivity of 91.1%, Wright's stain of 82.2% and light microscopy of 66.7% in detecting a glomerular source of hematuria. Nonglomerular hematuria could be detected in 92.9% cases by each of the 3 methods. It is concluded that phase contrast microscopy is most sensitive for the detection of dysmorphic RBCs in the urine, Wright's stain nearly as sensitive whilst light microscopy of the unstained sediment is least sensitive. Urinary RBC morphology is a useful adjunct in the diagnosis of hematuria and saves the patients from unnecessary investigations.

Adolescent↗
PubMed2002

Pronuclear abnormalities and cytoskeletal organization during assisted fertilization in a patient with multifollicular ovarian response.

PURPOSE: To analyze the distribution of a tubulins and acetylated alpha tubulins and the chromatin configuration in abnormally fertilized zygotes from a patient with a multifollicular ovarian response after in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). METHODS: Immunofluorescence and phase contrast microscopy was performed in abnormally fertilized zygotes. RESULTS: After phase contrast microscopy analysis, immunofluorescence staining was performed in 20 oocytes that developed > or = 3 pronuclei (PN) and karyomeres after IVF-ICSI. Around 80% of the abnormal zygotes from IVF were the consequence of monospermic fertilizations. Retention of the second polar body (PB) and the presumptive split of > or =1 PN within the cytoplasm were the main events present in most oocytes after IVF-ICSI. CONCLUSIONS: Fluorescence labeling of selected sperm and oocyte components affords a unique view of abnormal fertilized zygotes. Surprisingly, anomalies detected after IVF-ICSI showed similar etiologies in this special group of zygotes.

Acetylation↗
PubMedDate not supplied

The influence of titanium abutment surface roughness on plaque accumulation and gingivitis: short-term observations.

The roughness of intraoral hard surfaces plays an important role in bacterial adhesion and colonization. Earlier studies have shown that rough surfaces accumulate up to 25 times more subgingival plaque than do smooth sites. In the present study, the influence of surface smoothing was studied. In six partially edentulous patients waiting for a fixed prosthesis supported by endosseous titanium implants, four titanium abutments with different surface roughness were randomly placed. After 1 month of intraoral exposure, subgingival plaque samples from each abutment were compared within each patient by means of differential phase-contrast microscopy. After 3 months, supragingival and subgingival plaque samples were taken from all abutments for differential phase-contrast microscopy and culturing. Probing depth, recession, and bleeding upon probing were scored at the same visit. Differential phase-contrast microscopy showed that subgingivally, only the two roughest abutments harbored spirochetes after 1 month. After 3 months, subgingivally, the composition of the flora showed little variation on the different abutment types, although spirochetes were only noticed around the roughest abutments. Anaerobic culturing resulted in comparable amounts of colony-forming units for all abutment types, both supragingivally and subgingivally. Subgingivally, the microbiologic composition did not show major interabutment differences. Clinically, small differences in probing depth were observed. The roughest abutment showed some attachment gain (0.2 mm) during 3 months, whereas all other abutments had an attachment loss ranging from 0.8 to greater than 1 mm. The results indicate that a reduction in surface roughness (less than a roughness of 0.2 micron) had no major effect on the microbiologic composition, supragingivally or subgingivally. These observations indicate the existence of a threshold roughness below which no further impact on the bacterial adhesion and/or colonization should be expected. However, clinical evaluation seems to indicate that a certain surface roughness is necessary for increased resistance to clinical probing.

Bacteria, Anaerobic↗
PubMed1984

Expression of epithelial antigens in primary cultures of normal human breast analysed with monoclonal antibodies.

Primary cultures of normal human breast were stained with monoclonal antibodies to see if antigens characteristic of luminal epithelial cells are retained in culture. Three monoclonal antibodies were used, LICR-LON-M8, LICR-LON-M18, and LICR-LON-M24, all specific for the cell surface of luminal epithelial as opposed to myoepithelial or stromal cells in the breast, and each staining a different subset of the epithelial cells in the intact tissue. Cultures were prepared from reduction mammoplasty samples by digestion with collagenase. The surface layer of cells was stained by immunofluorescence without fixation. (Cells underneath the surface layer were not accessible to this mode of staining). The antibodies stained patches of cells resembling flattened epithelium. These patches of cells cannot be distinguished by phase contrast microscopy without reference to the staining, in fact the boundaries of the cells are not usually resolved by phase contrast microscopy. Electron microscopy of sections through these cells show they are very flattened. They lie on top of the polygonal and elongated cells that dominate the phase contrast image. Two of the antibodies, M8 and M24, stain subsets of these epithelial-like cells at all stages of culture. The third antibody, M18, stains such cells initially, but after the first few days staining is predominantly found on the polygonal and elongated cells, then this also gradually disappears. It is possible that the cells stained by antibody M18 are converting from the epithelial-like morphology to the cuboidal and elongated morphology. Many cells are not stained by any of the antibodies, so appear either to by myoepithelial in origin or to have lost their luminal epithelial surface antigens at an early stage. This analysis draws attention to the variety of cell types in these cultures and the limitations of phase contrast microscopy as a means of analysing them.

Antibodies, Monoclonal↗
PubMed2003

[Identification of asbestos in bulk materials by polarised light microscopy and phase contrast--method and results].

The implementation of the 1997 law on the banned use of asbestos, entailing a successive elimination of asbestos products, is planned for 30 years. Asbestos identification in samples of bulk materials is essential before starting dismantling works. The presented method of asbestos identification by polarized light microscopy and phase contrast involves the study of the following optical parameters of asbestos fibers: color, morphology, refractive index, anisotropy, pleochroism, optic nature and extinguish angle. The major advantages of this method are: small material samples, short time of analysis, high asbestos sample detectability (0.1%) and high reliability of results. This paper presents the results of asbestos identification in over a dozen of samples of bulk materials derived from various buildings and installations.

Asbestos↗
PubMedDate not supplied

[A simple and reliable method of preparing "permanent" biopreparations of different-origin cells for phase-contrast optical microscopy].

A simple method for obtaining "permanent" preparations of biological objects fixed with formalin vapors. 1.5% potassium permanganate solution, dehydrated with acetone, and embedded in Canadian balm is proposed. Such preparations may be used for preliminary morphologic assessment of the studied biological material intended for electron-microscopic examination.

Cheek↗
PubMed2001

Problems with platelet counting in thrombocytopenia. A rapid manual method to measure low platelet counts.

Because most automated platelet counters cannot be relied on in thrombocytopenia, clinicians face a problem when decision making is based on platelet counts. Therefore we evaluated a visual platelet counting method from a blood smear with white blood cells (WBCs) as reference (PCW = platelet count based on WBC). Platelet counting for 74 thrombocytopenic (<120 x 10(9)/L) children was performed with PCW and with an automated counter (impedance principle); both methods were compared with evaluation by phase-contrast microscopy as the standard method. The PCW correlated well with the phase-contrast microscopy evaluation (y = -0.38 + 1.01x, r2 = 0.99). For platelet counts <20 x 10(9)/L the maximal deviation was 2 x 10(9)/L. The correlation between automated counts and the standard method was poor. The regression was y = 9.63 + 0.94x, r2 = 0.86. For platelet counts <20 x 10(9)/L the maximal deviation was 37 x 10(9)/L; on average, 7 x 10(9)/L platelets were counted in excess when compared with the standard method. PCW, in contrast to the automated impedance method, discriminated platelets from nonplatelet particles such as debris, fragments of red blood cells (hemolytic-uremic syndrome [HUS]) and of blast cells, and identified platelets of abnormal size. In addition, the appearance ofplatelets, WBCs, and RBCs gave clues to the etiology of thrombocytopenia, such as leukemia, infection, HUS, familial macrothrombocytopenia, and immune thrombocytopenia. PCW is a fast, reliable platelet counting method requiring less experience than the phase-contrast method. Visual evaluation from a stained smear clearly differentiates platelets and nonplatelet particles in contrast to most automated counters. In addition, the original smear can be preserved and reevaluated.

Blood Platelets↗