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At least 19 recordsLinked to original sources
PubMed1993

Ischemia-reperfusion induced microvascular dysfunction in skeletal muscle: application of intravital video microscopy.

Video microscopy of red cell flow in capillaries at the surface of skeletal muscle provided the opportunity to quantitate ischemia-reperfusion (I-R) induced microcirculatory changes, in vivo. Extensor Digitorum Longus (EDL) muscles of 22 male Wistar rats (300-400 g), anesthetized with sodium pentobarbital (Somnotol, 65 mg kg,-1 IP), were used to measure the number of perfused capillaries (CDper: mm-1) crossing lines drawn perpendicular to the muscle axis, and red blood cell velocity (VRBC: mm/s) within individual capillaries from controls (n = 6), and after 2 hr (n = 4), 3 hr (n = 4), and 4 hr (n = 5) of no-flow ischemia with the muscle temperature maintained at its normal value of 32 degrees C. Ischemia was induced by tightening a tourniquet placed around the limb above the EDL muscle. Measurements were made after 30, 60, and 90 min of reperfusion. To test the usefulness of this skeletal muscle model for evaluating proposed interventions in I-R, the effect of hypothermia (24 degrees C) on the microcirculation following 4 hr ischemia (n = 3) was measured. Edema formation was estimated from the wet/dry weight ratio of the ischemic and contralateral control EDL muscles. Capillary perfusion at the surface of the control muscles was remarkably stable over the 5 hr period studied, while significant changes occurred following the ischemic periods. Significantly lower CDper was measured 30 min following all periods of normothermic ischemia. However, unlike the 2 and 4 hr ischemic periods 3 hr normothermic ischemia resulted in a progressive decline in CDper throughout the reperfusion period. VRBC showed evidence of a hyperemic response following 2 hr normothermic ischemia (control: 0.12 mm/s +/- 0.19 compared to 0.26 mm/s +/- 0.03 following 90 min reperfusion; mean +/- sem). However, no such hyperemia was measured following either 3 or 4 hr normothermic ischemia (i.e., 3 hr control: 0.24 mm/s +/- 0.01 compared to 0.07 mm s +/- 0.003 following 90 min reperfusion). In fact, VRBC was essentially zero 90 min following 4 hr normothermic ischemia (0.01 mm/s +/- 0.01). However, when the muscle was allowed to cool to 24 degrees C during 4 hr ischemia no significant change in either VRBC or CDper was measured compared to pre-ischemic controls. Evidence of edema was found after 3 and 4 hr normothermic ischemia. This study establishes a skeletal muscle model of I-R, which may be useful in testing hypotheses regarding mechanisms of I-R injury, and effectiveness of proposed treatments of I-R.

Animals↗
PubMed1994

Detection of minute intestinal metaplastic lesions by video microscopy.

Using video microscopy in 225 resected stomachs we detected 32 minute solitary lesions of intestinal metaplasia histologically. The magnified features of the minute lesions showed a characteristic appearance and were classified into three types: mesh-like (type A), villoid (type B), and tubular (type C). All the lesions classified as type A exhibited the incomplete type of intestinal metaplasia according to the results of histopathological and/or histochemical examination. In contrast, most lesions classified as type B exhibited the complete type of intestinal metaplasia. We concluded that intentional detection of minute lesions in resected stomachs by video microscopy is simple and useful, especially in cases of minute lesions < 5 mm in diameter. Moreover, our findings demonstrate that the minute intestinal metaplastic lesions have morphological characteristics based on which they can be classified into three types of lesions. These morphological characteristics correlate with their histopathological findings.

Adult↗
PubMed1992

Direct detection of immunogold reactions by real-time video microscopy.

Video-enhanced microscopy allows the detection and tracking of individual colloidal gold particles. The analysis of immunogold reactions can also be conducted as a function of time and thus allows the study of dynamic events in living cells. The direct visualization in real time is reported of the reaction of immunogold particles with a surface antigen. This time-resolved immunocytochemistry was achieved by continuous observation of living cells infected with a virus (respiratory syncytial virus) following their incubation with colloidal gold (30 nm) coated with antiviral antibodies. The progress of the immunoreaction was visualized as a sequential deposition of individual gold granules on the viral particles until saturation was reached after 60 min. Binding of colloidal gold was an irreversible event as no elution or dislocation of surface-bound granules took place. Comparative imaging of colloidal gold particles by electron microscopy and by video microscopy demonstrated that the video-imaged immunoreactions represented events involving single gold particles; their signal was sometimes clearly enhanced by secondary depositions taking place in close proximity, i.e. at a distance below the lateral resolution of the light microscope. Our experiments demonstrate that video-enhanced microscopy provides a powerful tool for studying antibody-antigen reactions with a high spatial and temporal resolution.

Animals↗
PubMed1994

Tacalcitol in psoriasis: a video-microscopy study.

Video-microscopy is a video-imaging system which permits direct visualization of the skin surface and capillaries, by using a microscope attached to a camera, a video-recorder and a printer. This technique provides information on the morphology of capillaries in vivo and has been used both for research into normal skin microcirculation and as a clinical method to detect capillary changes in psoriasis and other skin diseases. The aim of this study was to evaluate the morphology of capillaries in psoriatic plaques before and after treatment with tacalcitol, a new topical vitamin D3 analogue. Clinical evaluation was made after 3 and 6 weeks of therapy. After 3 weeks a reduction in erythema and scaling was noted; and areas in which capillaries were less tortuous became evident. After 6 weeks, capillaries were less dilated and tortuous in the whole plaque and had lost the large and tortuous appearance of active psoriasis.

Adult↗
PubMed1988

Progress in video microscopy.

The progress in video microscopy is reviewed from its early inception, especially with respect to improvements of the microscope image quality. Very recent advances that provide serial optical sections and depth of field as thin as 0.1 micron and that make possible the recording of birefringent images of individual microtubules (25 nm in diameter) directly in live, dividing cells are also documented.

Animals↗
PubMed1993

Scanning and transmission electron microscopy and high resolution intravital video-microscopy of capillaries in the mouse exocrine pancreas, with special emphasis on endothelial cells.

Capillaries in the mouse exocrine pancreas were studied by scanning electron microscopy of microvascular corrosion casts, transmission electron microscopy of tissue sections, and high resolution intravital video-microscopy. Two types of capillaries were discerned by corrosion casting. The first type was rather straight, had a constant diameter of 5-6 microns, and its surface showed multiple circumferential furrows. The frequency of such constrictions was less in the second type, which was more undulated and had a diameter of 7-9 microns. In the second type, these constrictions defined bulged areas of the capillary cast. Corresponding tissue sections also showed two types of capillaries, fenestrated and non-fenestrated capillaries. Microtubules were abundant in all capillary endothelial cells, whereas bundles of microfilaments were scarce. Microtubules were arranged along the long axis of endothelial cells as well as parallel to endothelial cell border regions. Endothelial cells were joined by intermediate junctions along cell borders running both circumferentially and longitudinally. Flow reversal in capillaries and spontaneous endothelial contractions were documented in vivo. Endothelial cells bulged into the lumen, either at their nuclear region or distant from it. Spontaneous contraction of pericytes was not observed. These results suggest that contraction of capillaries is carried out by endothelial cells, representing an autonomous flow regulatory device. Capillary contraction in exocrine pancreas may be influenced by blood-borne agents, probably by those released in Langerhans islets.

Animals↗
PubMed1992

Human performance studies of the video microscopy component of a dynamic telepathology system.

Human performance studies were performed to evaluate the video microscopy component of a proposed dynamic telepathology system. Frozen sections from breast biopsies of 115 patients were evaluated by both conventional light microscopy and video microscopy by 6 pathologists. Receiver operator characteristic (ROC) curve studies showed nearly identical levels of discrimination between benign and malignant breast lesions for both viewing modalities. Viewing times were significantly greater (p < 0.001) for video microscopy but within a time frame that rendered the technology of potential value for pathology diagnostic applications. Large degrees of interobserver viewing time variability were found for light and video microscopy.

Biopsy↗
PubMed1992

The validity of frozen section diagnosis based on video-microscopy.

To investigate the accuracy of video-microscopy of frozen sections, two pathologists reexamined 80 cases of archival material, on which frozen sections had previously been performed. Diagnoses based on the two trials (Observer 1 and 2) and diagnoses obtained in the original frozen section situation were compared with the final diagnoses based on paraffin embedded material. Observer 1 had two false negative diagnoses, but no false positive, whereas Observer 2 had one false positive, but no false negative diagnosis when compared with the final diagnoses. No false positive or false negative diagnoses were made in the original frozen sections situation and the number of inconclusive diagnoses were 5, as compared with 6 and 8 in the two trials based on video-microscopy. More experience with video-microscopy will probably achieve a quality of frozen section diagnoses similar to that of direct light-microscopy.

Diagnosis, Differential↗
PubMed1993

Analysis of lymphocyte activation and proliferation by video microscopy and digital imaging.

Video microscopy and digital imaging were used as a noninvasive method to quantitatively analyze lymphocyte activation and proliferation. This method takes advantage of the fact that upon activation lymphocytes blast and become significantly larger before proliferating. The mean cell sizes of T lymphocytes in an activation kinetics assay were measured by digital image analysis and compared to [3H]-thymidine incorporation of cells under the same treatment. An increase in cell size was observed before [3H]-thymidine incorporation; therefore the digital imaging assay is more sensitive in determining the earliest time-point of activation. Also, the digital imaging assay was comparable to the [3H]-thymidine incorporation assay in providing information about the extent and rates of T lymphocyte proliferation. Cellular DNA was stained with propidium iodide to show that the larger blasting cells in the population of activated T lymphocytes were indeed the cells that accounted for the increase in DNA synthesis and thus an increase in cell size can be correlated with activation.

Analog-Digital Conversion↗
PubMed1992

Brain microtubule-associated proteins modulate microtubule dynamic instability in vitro. Real-time observations using video microscopy.

We used video assays to study the dynamic instability behavior of individual microtubules assembled in vitro with purified tau, purified MAP2 or a preparation of unfractionated heat-stable MAPs. Axoneme-nucleated microtubules were assembled from pure tubulin at concentrations between 4 and 9 microM in the presence of MAPs, and observed by video-differential interference contrast microscopy. Microtubules co-assembled with each MAP preparation exhibited the elongation and rapid shortening phases and the abrupt transitions (catastrophe and rescue) characteristic of dynamic instability. Each MAP preparation increased the microtubule elongation rate above that for purified tubulin alone by decreasing the tubulin subunit dissociation rate during elongation. The brain MAPs used in this study reduced the rate of microtubule rapid shortening, but allowed significant loss of polymer during the shortening phase. Purified tau and MAP2 decreased the frequency of catastrophe and increased the frequency of rescue, while the heat-stable MAPs suppressed catastrophe at all but the lowest tubulin concentrations. Thus, each of these MAPs modulates, but does not abolish, dynamic instability behavior of microtubules. We propose a model to explain how MAP2 and tau bind to the microtubule lattice at sites along protofilaments so that the MAPs promote polymerization, but do not significantly block the mechanism of rapid shortening inherent in the tubulin lattice. Rapid shortening, when it occurs, proceeds primarily by the dissociation of short fragments of protofilaments, which contain the bound MAPs.

Animals↗
PubMed1993

Video microscopy of organelle inheritance and motility in budding yeast.

By adapting the time-lapse video microscopy techniques that were developed for larger, more complex cells, to living Saccharomyces cerevisiae cells, intracellular organelle movements were observed. Differential interference contrast optics revealed an organelle transport process in cells treated with mating pheromone. Small particles were observed to travel distances of up to 6 microns at rates of 0.11-0.17 (and in one case 0.80) micron/sec. Overall, the frequency of these motile events was quite low compared to what is observed in cell types traditionally studied by video microscopy. The ability to discern clearly the vacuole and nucleus in budding yeast revealed the dynamics of these organelles and the fact that their movements are carefully orchestrated during the cell cycle. Two types of vacuolar dynamics were observed: 1) interconversion between one large organelle and numerous smaller organelles and 2) the formation of projections that extend from the mother cell's vacuole into the bud. When applied to the study of the many available cytoskeletal and cell cycle mutants, the application of video microscopy to the study of organelle movements in living yeast cells will provide a unique opportunity to determine the molecular mechanisms of intracellular motility and to elucidate the temporal controls over these processes.

Biological Transport↗
PubMed1995

Tracking movements of lipids and Thy1 molecules in the plasmalemma of living fibroblasts by fluorescence video microscopy with nanometer scale precision.

The lateral diffusion of 100 nm fluorescent latex microspheres (FS) bound to either N-biotinyl-phosphatidyl-ethanolamine or the glycosylphosphatidylinositol-linked protein Thy1 were monitored in the plasmalemma of primary rat fibroblasts by single particle tracking of FS centroids from digital fluorescence micrographs. A silicon intensified target camera was found to be superior to slow scan cooled CCD and intensified interline transfer CCD cameras for monitoring lateral diffusion of rapidly moving FS with nanometer level precision. To estimate the maximum tracking precision, a 4 sec-sequence comprising 120 images of FS fixed to a cover glass was obtained. The mean distance of the centroids from the origin was 7.5 +/- 0.4 nm, and no centroids were beyond 16 nm from the origin. The SIT camera was then used to track FS attached to lipids and Thy1 molecules on the surface of fibroblasts. The lateral diffusion of lipid-bound FS was unconstrained, and the ensemble averaged diffusion coefficient was 0.80 x 10(-9) cm2/sec. Thy1-bound FS existed in two mobility populations, both of which demonstrated constrained mobility. The rapidly moving population, comprising 61% of the total, had an ensemble diffusion coefficient of 6.1 x 10(-10) cm2/sec, and appeared to be restricted to domains with a mean length of about 700 nm. The slowly moving population, comprising about 39% of the total, had a diffusion coefficient of 5.7 x 10(-12) cm2/sec. These results demonstrate that nanovid can be extended to the realm of fluorescence microscopy and support previous studies indicating that while the lateral mobilities of at least some lipids are not constrained to small domains by barriers to lateral diffusion in the fibroblast plasmalemma, a peripheral membrane protein which is bound only by a lipid anchor can be prevented from diffusing freely.

Animals↗
PubMed1985

Simultaneous assessment of red cell perfusion in skeletal muscle by laser Doppler flowmetry and video microscopy.

The objective of this study was to compare temporal and spatial variations of the laser Doppler flowmeter output (V) with the corresponding variations of perfusion (cells/mm3 X mm/s) evaluated by video microscopy. The flowmetry and video microscopy sampled 2 mm3 (approx.) and 0.84 mm3 surface volumes of the sartorius muscle in anesthetized frogs, respectively. The overall ranges of the output and perfusion measurements were from 0.01 to 0.72 V and from 45 to 1404 cells/mm3 X mm/s. Within these ranges, temporal variations induced by muscle contraction correlated well (overall r = 0.91), but the spatial variations associated with the resting state correlated poorly (overall r = 0.45). When the penetration of the laser light was limited to 0.3-0.4 mm (to make the volumes sampled by both techniques more comparable) the overall r of the spatial comparison increased to 0.86. It is concluded that the flowmeter (1) is affected by red cell perfusion below the tissue depth of 0.3-0.4 mm, and (2) can follow both the temporal and spatial variations of red cell perfusion in the tissue examined.

Capillaries↗
PubMed1994

Digital video microscopy for the undergraduate histology laboratory.

An undergraduate histology course was profoundly changed through the introduction of digital video microscopy. Students have access to a networked, Macintosh-based imaging laboratory where they can digitally capture, enhance, analyse, and media output microscope originated images. By increasing the access to image information, students are able to assume a more active inquiry mode in a microscope-based course. The technology allowed students to increase intellectual sharing among themselves and to leave 'digital legacies' for future classes.

Computer Communication Networks↗
PubMed1990

Observation of single influenza virus-cell fusion and measurement by fluorescence video microscopy.

We have used intensified video fluorescence microscopy and digital image processing to observe and quantitate influenza virus (A/PR8/34/H1N1) fusion to human erythrocyte membranes. Viruses labeled with the lipid probe octadecylrhodamine B (R18) were seen to undergo fluorescence dequenching and eventual disappearance after exposure to pH levels known to induce virus-cell membrane fusion. Quantitative intensity measurements of single individual particles were possible. From these fluorescence data it has been possible to calculate the fraction of R18 dye molecules transferred from the virus to the cell. The redistribution of the lipid probe upon fusion at pH 5.0 had a t1/2 of 46 s, longer than expected for a free-diffusion model. The R18 loss was approximately twice as fast at pH 5.0 as at pH 5.1. No obvious delay until the start of fluorescence dequenching was observed after the pH changes, suggesting that activation processes are faster than the time resolution, 1-5 s, of the current method.

Erythrocyte Membrane↗