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At least 883 records · Page 49Linked to original sources
PubMed1983

[Assessment of blood platelet status in acute myocardial infarction].

Circulating platelet morphology (using scanning electron microscopy), platelet adhesion and flattening on silicone slides (interference contrast microscopy), and spontaneous platelet aggregation were investigated. Platelet status was thus assessed in patients with acute myocardial infarction (AMI), chronic coronary disease (CCD) and normal subjects (controls). In AMI patients, the majority of circulating platelets were inactivated: 70% and more were of smooth discoid shape, a finding similar to that of the controls. On the contrary, platelet flattening, adhesion and spontaneous aggregation were changed in AMI patients, and also, though on a smaller scale, in CCD patients. Changes in platelet flattening ability were most pronounced, the latter parameter being sharply increased in 73% of AMI patients.

Adolescent↗
PubMed1991

Rapid diagnosis of malaria by fluorescence microscopy with light microscope and interference filter.

Fluorochrome staining to detect malaria parasites in bloodfilms is more sensitive, is easier to do, and is less time-consuming than Giemsa staining. However, standard epi-illuminated, mercury vapour, fluorescence microscopes are expensive, especially for tropical countries where malaria is endemic. Fluorescence microscopy with a standard light microscope and a new interference filter specially designed for the fluorochrome stain, acridine orange, was used to detect malaria parasites in thick and thin bloodfilms. In this system two fluorescence colours, green (nuclei) and red (cytoplasm), were emitted from stained parasites. Thick and thin bloodfilms from patients with malaria were examined with this system. Bloodfilms had been fixed and stored for 1-5 years. Rapid scanning of both thick and thin bloodfilms was possible at a magnification of x200 with standard lenses, indicating that this may be a useful economic system for rapid diagnosis of malarias.

Acridine Orange↗
PubMed1984

Cell-substratum interaction of cultured avian osteoclasts is mediated by specific adhesion structures.

The cell-substratum interaction was studied in cultures of osteoclasts isolated from the medullary bone of laying hens kept on low calcium diet. In fully spread osteoclasts, cell-substratum adhesion mostly occurred within a continuous paramarginal area that corresponded also to the location of a thick network of intermediate filaments of the vimentin type. In this area, regular rows of short protrusions contacting the substratum and often forming a cup-shaped adhesion area were observed in the electron microscope. These short protrusions showed a core of F-actin-containing material presumably organized as a network of microfilaments and surrounded by a rosette-like structure in which vinculin and alpha-actinin were found by immunofluorescence microscopy. Rosettes were superposable to dark circles in interference-reflection microscopy and thus represented circular forms of close cell-substratum contact. The core of ventral protrusions also contained, beside F-actin, fimbrin and alpha-actinin. Villin was absent. This form of cell-substratum contact occurring at the tip of a short ventral protrusion differed from other forms of cell-substratum contact and represented an osteoclast-specific adhesion device that might also be present in in vivo osteoclasts as well as in other normal and transformed cell types.

Actinin↗
PubMed1985

Critical-point drying versus freeze drying for scanning electron microscopy: a quantitative and qualitative study on isolated hepatocytes.

Critical-point drying and freeze drying were compared both quantitatively and qualitatively as preparative procedures for scanning electron microscopy. Isolated hepatocytes were used as model cells. Nomarski differential interference contrast microscopy was used for light microscopic measurements of the hepatocytes in the unfixed, the glutaraldehyde fixed, the glutaraldehyde + OsO4 fixed, the critical-point dried and the freeze dried states. Critical-point dried hepatocytes were found to shrink to 38% of glutaraldehyde + OsO4 fixed volume, whereas optimal freeze dried hepatocytes (frozen in water saturated with chloroform and freeze dried at 183 K for 84 h) were found to shrink to 51% of glutaraldehyde + OsO4 fixed volume. Transmission and scanning electron micrographs of the critical-point dried cells showed well-preserved ultrastructure and surface structure. Micrographs of the freeze dried cells showed ultrastructure destroyed by internal ice crystals and surface structure destroyed by external ice crystals. Double-fixed isolated hepatocytes were shown to swell during storage in buffer and to shrink during storage after critical-point drying. For low magnification scanning electron microscopy (up to about 3000 times) both critical-point drying and freeze drying can be used. However, for high magnification scanning electron microscopy, critical-point drying is superior to freeze drying.

Animals↗
PubMed1983

Influence of cooling rates and extenders upon post-thaw viability of bovine spermatozoa packaged in .25- and .5-ml French straws.

Post-thaw survival of bovine spermatozoa was compared for semen packaged in either .25- or .5-ml French straws and frozen at three different cooling rates in moving N2 vapor. Using a split ejaculate technique, nine ejaculates were extended in heated skim milk, egg yolk-citrate and egg yolk-Tris and packaged in .25- and .5-ml French straws. Semen packaged in the .25- and .5-ml straws was frozen simultaneously at initial N2 vapor temperatures of -140, -110 or -80 C. Semen was thawed in a water bath at 35 C for 1 min. Recovery of spermatozoa was evaluated immediately post-thaw (0 h) and again after 3 h of incubation at 37 C. Motility estimates and motility counts were made using phase contrast microscopy; percentage of spermatozoa possessing intact acrosomes was quantitated using differential interference contrast microscopy. There was a packaging unit X cooling rate interaction (P less than .05) for all three viability measures. However, there was no consistent trend with regard to cooling rate or packaging unit among the three extenders examined. Post-thaw viability for each characteristic varied (P less than .01) among extenders, but not for cooling rate or packaging unit (P greater than .05). Spermatozoa extended and frozen in egg yolk-Tris had greater (P less than .05) post-thaw viability than those extended in skim milk or egg yolk-citrate regardless of cooling rate or volume of the seminal package.

Acrosome↗
PubMed1981

Changes in microfilament and focal adhesion distribution with loss of androgen responsiveness in cultured mammary tumor cells.

The actin-containing microfilaments, microtubules, and fibronectin expression of Shionogi 115 mouse mammary tumor cells were visualized by indirect immunofluorescence microscopy. Also studied was the focal adhesion distribution as revealed by interference reflection microscopy and the ability of the cells to grow in suspension culture. All these parameters were documented for androgen-responsive and -unresponsive cells grown in culture, as well as the transition of androgen-responsive to -unresponsive cells when deprived of androgen. The androgen-unresponsive cells had extensive and prominent microfilament bundles together with focal adhesions on the lower cell surface and also showed strict anchorage dependence for growth. In contrast, microfilament bundles and focal adhesions were absent from androgen-responsive cells, which furthermore had the ability to grow in suspension culture. Differences were also apparent in fibronectin expression, the androgen-unresponsive cells having more of this glycoprotein detectable on their surfaces than the androgen-responsive cells. The androgen-responsive and -unresponsive cells had similar microtubule arrays, however. During the transition from the androgen-responsive to the androgen-unresponsive phenotype, the androgen-responsive cells gradually took on the characteristics of androgen-unresponsive cells as judged by cellular morphology or the presence of focal adhesions and microfilament bundles. At intermediate stages in this process, characteristics of both cell types were visible in the cell populations. However, at the stage where all androgen-responsive characteristics were lost, the cells were no longer androgen sensitive. The loss of androgen responsiveness in Shionogi 115 mouse mammary tumor cells is correlated with changes at the cell membrane and the microfilament component of the cytoskeleton.

Animals↗
PubMed1985

A photoetched cell relocation matrix for long-term, quantitative observations of selected individual neurons in culture.

A photoetched matrix of indium tin oxide (ITO) on glass has been developed and tested as a tool to assist in the relocation and identification of individual neuronal cells in culture. The matrix is formed by 10-15 micron wide and 300 A thick ITO lines which subdivide a 1-cm2 area into 625 smaller squares. Each of the smaller squares measures 400 micron on a side and contains a photoetched two-letter "address". The address code allows precise relocation of specific regions of a culture as well as verification of the identities of individual neurons selected for repeated observation. Marks at 50 micron intervals along the sides of the address squares permit quantitative analysis of morphological changes, cell migration, reaggregation, etc. The ITO is transparent and does not interfere with visualization of even fine details of cells with high power microscopy.

Animals↗
PubMed2001

Cell reactions with biomaterials: the microscopies.

The methods and results of optical microscopy that can be used to observe cell reactions to biomaterials are Interference Reflection Microscopy (IRM), Total Internal Reflection Fluorescence Microscopy (TIRFM), Surface Plasmon Resonance Microscopy (SPRM) and Förster Resonance Energy Transfer Microscopy (FRETM) and Standing Wave Fluorescence Microscopy. The last three are new developments, which have not yet been fully perfected. TIRFM and SPRM are evanescent wave methods. The physics of these methods depend upon optical phenomena at interfaces. All these methods give information on the dimensions of the gap between cell and the substratum to which it is adhering and thus are especially suited to work with biomaterials. IRM and FRETM can be used on opaque surfaces though image interpretation is especially difficult for IRM on a reflecting opaque surface. These methods are compared with several electron microscopical methods for studying cell adhesion to substrata. These methods all yield fairly consistent results and show that the cell to substratum distance on many materials is in the range 5 to 30 nm. The area of contact relative to the total projected area of the cell may vary from a few per cent to close to 100% depending on the cell type and substratum. These methods show that those discrete contact areas well known as focal contacts are frequently present. The results of FRETM suggest that the separation from the substratum even in a focal contact is about 5 nm.

Journal Article↗