SEARCH · PubMed Health

Results for “Microscopy, Video”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

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

At least 73 records · Page 4Linked to original sources

PubMed1987

Nanovid tracking: a new automatic method for the study of mobility in living cells based on colloidal gold and video microscopy.

We describe a new automatic technique for the study of intracellular mobility. It is based on the visualization of colloidal gold particles by video-enhanced contrast light microscopy (nanometer video microscopy) combined with modern tracking algorithms and image processing hardware. The approach can be used for determining the complete statistics of saltatory motility of a large number of individual moving markers. Complete distributions of jump time, jump velocity, stop time, and orientation can be generated. We also show that this method allows one to study the characteristics of random motion in the cytoplasm of living cells or on cell membranes. The concept is illustrated by two studies. First we present the motility of colloidal gold in an in vitro system of microtubules and a protein extract containing a kinesin-like factor. The algorithm is thoroughly tested by manual tracking of the videotapes. The second study involves the motion of gold particles microinjected in the cytoplasm of PTK-2 cells. Here the results are compared to a study using the spreading of colloidal gold particles after microinjection.

Animals↗

PubMed1988

Direct observation of the budding and fusion of an enveloped virus by video microscopy of viable cells.

Video-enhanced microscopy and digital image processing were used to observe the assembly, budding, and fusion of Respiratory Syncytial virus. Viral filaments were seen to bud from the plasma membrane of viable infected cells to a final length of 5-10 micron with an average speed of elongation of 110-250 nm/s. The rapidity of viral assembly and its synchronous occurrence (leading to the production of several viral particles per minute from the same surface domain) suggests a directed process of recruitment of viral components to an area selected for virus maturation. Virions were also seen to adsorb to the cell surface, and to fuse with the plasma membrane. These are the first real time observations of viral morphogenesis and penetration which are crucial events in the infectious cycle of enveloped viruses.

Antibodies, Monoclonal↗

PubMed1988

Simultaneous Nomarski and fluorescence imaging during video microscopy of cells.

A video microscope designed to allow low light level fluorescence imaging of cells during simultaneous high-resolution differential interference contrast (DIC) imaging, without the fluorescence light losses of 60-90% normally associated with this contrast-enhancement technique, is described. Transmitted light for DIC imaging, filtered at greater than 620 nm, passes through standard DIC optical components, (1/4 lambda-plate, polarizer, and Wollaston prism) before illuminating the cells. Transmitted light and fluorescence emission pass through a second Wollaston prism but not through the analyzer, which is repositioned more distally in the optical path. Prisms designed to reflect light out a side port of the microscope to a video camera have been replaced with a dichroic mirror. This mirror reflects fluorescence emission out the side port to a low light-sensitive video camera. The spectrally distinct transmitted light continues through the dichroic mirror to an overhead camera through a polarizer (analyzer), which completes the DIC optical path. The fluorescence and DIC images can be viewed simultaneously on side-by-side video monitors, examined sequentially by an image-processing computer, or examined simultaneously using a video splitter/inserter. The ability to image cells with high resolution simultaneously with low light level fluorescence imaging should find wide applicability whenever it is necessary or desirable to correlate fluorescence intensity or distribution with specific cell structure or function.

Animals↗

PubMed2001

Technique for using video microscopy and indicator dilution for repeated measurements of cardiac output in small animals.

BACKGROUND: The authors developed an indicator dilution technique for small animals to repeatedly determine cardiac output and blood volume without cardiac instrumentation or blood sampling. METHODS: Observations were made in the hamster (N = 32, 70 mg/kg pentobarbital) cremaster using in vivo fluorescence videomicroscopy. Fluorescein isothiocyanate-conjugated bovine serum albumin (10 mg/ml) was injected as a bolus dose (right jugular) while video recording the light intensity in a 20-microm arteriole (intensified charge-coupled device [CCD] camera at fixed gain). The intensity signal was analyzed over time (background subtracted) and calibrated to the dye concentration. The ex vivo calibration was performed using a constant optical path length (20 microm) and a range of dye and hematocrit concentrations. In vivo tube hematocrit was determined using standard methods with fluorescently labeled erythrocytes. Thus, quenching of the fluorescence signal by hemoglobin was corrected for the calibration, and the plasma space in the arteriole was determined. The steady state dye concentration measured by the light intensity at 2 min was not different from the dye concentration found by direct spectrophotometric analysis of the plasma. RESULTS: Cardiac index was calculated as milliliters of blood per minute per kilogram body weight. The calculated cardiac index was 359 +/- 18 ml.min(-1).kg(-1), which is not different from the reported values for hamsters. Cardiac output was increased twofold when enough intravenous nitroprusside or nitroglycerine was injected to decrease mean arterial pressure from 90 to 70 mmHg. Cardiac output was elevated during dobutamine infusion (16 microg.kg(-1).min(-1)) and decreased during esmolol infusion (50, 75.kg(-1).min(-1)). Blood volume determined from the steady state dye concentrations was 6.2 +/- 0.5 ml/100 g body weight, within the normal range for hamsters. CONCLUSIONS: Fluorescent dye dilution and video microscopy can be used to repeatedly determine cardiac output or blood volume in small animals.

Animals↗

PubMed1994

Use of digitized video microscopy with a fluorogenic enzyme substrate to demonstrate cell- and compartment-specific gene expression in Salmonella enteritidis and Bacillus subtilis.

A rapid and sensitive method for detection of cell- and compartment-specific gene expression in individual cells of both Gram-negative and Gram-positive microorganisms is described. The method combines the use of gene fusions to lacZ, and a fluorogenic beta-galactosidase substrate, fluorescein-di-(beta-D-galactopyranoside), with digitized video microscopy. All of the reporter constructs tested were successfully detected. Secondary staining of the cells with a nucleic acid-specific dye, propidium iodide, allowed cells devoid of nucleic acid to be identified, while cell nucleoid shape and the morphological stage of development could be correlated with the location of beta-galactosidase activity. The double-staining procedure was used to show that gene expression can be induced in non-culturable cells of Salmonella enteritidis produced by carbon/nitrogen starvation. The resolution was sufficient to distinguish between cells at different morphological stages of sporulation in Bacillus subtilis. This highly sensitive and rapid method may have many other applications in basic and applied microbiology.

Bacillus subtilis↗

PubMed1990

Identification of riboflavin transport by MDCK cells using quantitative fluorescence video microscopy.

MDCK cells, when examined by low-light level video microscopy displayed an endogenous fluorescence with two differing patterns. A low intensity emission which was punctate and associated with cell organelles was observed with emission and excitation conditions generally used to observe either fluorescein (450-500 nm excitation/greater than 510 nm emission) or rhodamine (514 nm excitation/greater than 530 emission) type dyes. A second 5- to 10-fold brighter emission for 450-500 nm excitation was observed, which was unusual in that each cell appeared to be outlined. Evidence obtained from spectroscopy and from using culture media of altered composition supported the conclusion that the water-soluble vitamin riboflavin accumulated in the basolateral spaces and fluid-filled "domes" and was the source of this fluorescent emission. Quantitative measurements showed that exposure to cultures to 10 microM riboflavin resulted in accumulation in domes of 565 +/- 80 microM. The transport rate was calculated to be 189 +/- 30 pmol/min-cm2. One mM probenecid, a known inhibitor of riboflavin transport in vivo, reduced transport to 54% of control, while 10 mM nearly abolished the uptake. The results demonstrate that removal of riboflavin reduces MDCK cell fluorescence to levels compatible with low-light level imaging. Furthermore, these cells actively transport riboflavin and provide a new in vitro model for this process.

Animals↗

PubMedDate not supplied

Comparative blood compatibility of polyether vs polycarbonate urethanes by epifluorescent video microscopy.

The segmented polyether urethanes (PEUs) have been used in implantable medical devices due to excellent mechanical properties, acceptable blood compatibility, and good biostability. However, recent studies demonstrate that the polyether soft segment of PEU is susceptible to oxidative degradation in vivo due to scission of the polyether group. Recently, polycarbonate urethanes (PCUs) having no ether linkage in the soft segment have been developed, and show improved stability against oxidative degradation over PEUs. The current study evaluates blood compatibility of these PCUs in comparison with PEUs using epifluorescent video microscopy (EVM) combined with a parallel plate flow cell. The authors selected two PCUs, Corethane 80A (Corvita Corporation, Miami, FL) and PCU(1560), and two PEUs, Pellethene 2363-80AE (Dow Chemical Japan, Tokyo, Japan) and Tecoflex EG80A (Thermedics, Inc., Woburn, MA), all of which have similar hard segment compositions (MDI or HMDI:1,4-butanediol(BD)) and the same hardness of 80A. The EVM measured the amount of platelet coverage on the surfaces using human whole blood perfused at a wall shear rate of 100/sec for 20 min. Complement activation (C3a) also was measured. Both PEUs, especially Pellethane, showed significantly higher platelet adhesion than the PCUs (p < 0.05). There were no significant differences in platelet adhesion between the two PCUs. As for C3a measurements, Tecoflex showed higher complement activation than the others. Based on these results, it is recommended that PEUs should be replaced by ether free PCUs for use in implantable blood contacting devices such as artificial hearts and pacemaker lead insulators.

Biocompatible Materials↗

PubMed2002

Motility and ramification of human fetal microglia in culture: an investigation using time-lapse video microscopy and image analysis.

Microglia are mononuclear phagocytes of the central nervous system and are considered to derive from circulating bone marrow progenitors that colonize the developing human nervous system in the second trimester. They first appear as ameboid forms and progressively differentiate to process-bearing "ramified" forms with maturation. Signals driving this transformation are known to be partly derived from astrocytes. In this investigation we have used cocultures of astrocytes and microglia to demonstrate the relationship between motility and morphology of microglia associated with signals derived from astrocytes. Analysis of progressive cultures using time-lapse video microscopy clearly demonstrates the dynamic nature of microglia. We observe that ameboid microglial cells progressively ramify when cocultured with astrocytes, mirroring the "differentiation" of microglia in situ during development. We further demonstrate that individual cells undergo morphological transformations from "ramified" to "bipolar" to "tripolar" and "ameboid" states in accordance with local environmental cues associated with astrocytes in subconfluent cultures. Remarkably, cells are still capable of migration at velocities of 20-35 microm/h in a fully ramified state overlying confluent astrocytes, as determined by image analysis of motility. This is in keeping with the capacity of microglia for a rapid response to inflammatory cues in the CNS. We also demonstrate selective expression of the chemokines MIP-1alpha and MCP-1 by confluent human fetal astrocytes in cocultures and propose a role for these chemotactic cytokines as regulators of microglial motility and differentiation. The interchangeable morphological continuum of microglia supports the view that these cells represent a single heterogeneous population of resident mononuclear phagocytes capable of marked plasticity.

Astrocytes↗

PubMed2005

Video microscopy as an alternative method for somatic cell count in milk.

This paper presents an alternative method to estimate somatic cell count (SCC) in cows' milk. SCC is an important indicator in the detection of inflammatory reactions within the udder in cows and Direct Optical Microscopy (DOM) is the present reference method for SCC but, owing to its dependence on human operators, it is extremely costly, time-consuming and potentially subjective. The industrial method of choice is Epifluorescence (EF), which has the potential for impressive throughput and acceptable precision, but requires huge inversions and handling of highly toxic reactives and waste. In this paper, an advantageous method that involves application of a low-cost Video Microscopy (VM) system is analysed and discussed, including a comparison between DOM and VM, and an example of application of both methods to evaluate EF counts. We conclude that VM is sufficiently precise and very cheap to implement and operate.

Animals↗

PubMed1996

Paclitaxel-induced apoptotic changes followed by time-lapse video microscopy in cell lines established from head and neck cancer.

Paclitaxel (Taxol) is a potent chemotherapeutic drug for squamous-cell carcinoma (SCC) of the head and neck in vitro with microtubule-stabilizing activity that arrests cells in G2-M. To study the mechanism of its cytotoxic effect on SCC in vitro, we exposed five laryngeal SCC cell lines to 10 nM paclitaxel. The cell lines were studies by time-lapse video microscopy for 96 h, and by agarose gel electrophoresis. Paclitaxel blocked the cells in the premitotic phase for 6-24 h, after which the cells died morphologically by apoptosis. Mitotically arrested cells were seen within a few minutes after exposure to paclitaxel. No mitoses were seen in the paclitaxel-treated cells. A few apoptoses were also seen in the control cultures grown without paclitaxel, but they represented only 6%-20% of the frequency of apoptoses seen in the paclitaxel-treated group. In some paclitaxel-treated cultures the cells escaped the mitotic arrest without cytokinesis and formed multinucleated cells that eventually died. Agarose gel electrophoresis showed oligonucleosomal DNA fragmentation characteristic of apoptosis. We conclude that time-lapse video microscopy is an efficient method of observing drug-induced morphological changes in cell culture. Paclitaxel at a 10 nM concentration rapidly induces a premitotic block, which usually leads to apoptotic cell death. In some cases multinucleated cells are formed that morphologically also eventually die by apoptosis.

Antineoplastic Agents, Phytogenic↗

PubMed1999

Characterization of transient platelet contacts on a polyvinyl alcohol hydrogel by video microscopy.

Acridine orange labelled, washed human platelets were counted and tracked on polyvinyl alcohol (PVA), heparin-PVA and polyethylene (PE)-coated coverslips with a view to understand why transient contact on the PVA hydrogels lead to elevated platelet activation and consumption relative to polyethylene. Over the 4 min of initial contact that was studied, platelet adhesion was higher on PE than on PVA or heparin-PVA at both 40 and 200 s(-1), as expected, regardless of whether the surfaces were pre-treated with albumin or fibrinogen. Not all platelets appearing to make contact with the surface, actually attached. For example, less than 2% of the platelets contacting albumin pre-treated PVA (at 40 s(-1)) remained adherent at the end of the initial 60 s observation time, while the corresponding number for PE was greater than 9%. A greater fraction of the platelets remained adherent at the higher shear rate or with fibrinogen pre-treatment, but the difference between PVA and PE remained similar: for example, with fibrinogen pre-treatment at 200 s(-1), approximately 25% of the platelet contacts resulted in adhesion on PVA while 66% did so on PE. While net platelet adhesion was less for the hydrogels, than for PE, the total number of contacts (adherents + non-adherents) were more comparable and unexpectedly higher for albumin pre-treatment than for fibrinogen. Net platelet adhesion is but one component of the total platelet interaction with a material surface. Fluorescent video microscopy has been shown to be a useful, albeit not unequivocal, method for assessing the platelets that make contact with but do not adhere to a surface. reserved

Biocompatible Materials↗

PubMed1987

Time lapse video microscopy using an animation control unit.

A system for time lapse video microscopy incorporating an edit recorder and animation control unit is described, allowing both colour recording, forward and reverse playback without synchrony bars, and the identification of each individual frame recorded. This is achieved by using the edit recorder, controlled by the animation unit to produce continuous series of insert edits using the preroll facility of the recorder. A feature of this system is the preview of the last hour's recording which is constantly played as the preroll of the edit recorder. Tissue culture flasks modified for stable focus are also described.

Animals↗

PubMedDate not supplied

Effects of anti-atherosclerotic substances on smooth muscle cell migration and proliferation analyzed by time-lapse video microscopy.

A new approach to analyze possible anti-atherosclerotic effects of substances using time-lapse video microscopy is presented. Time-lapse video recording of cultured cells combined with the quantitative analysis of cellular migration and proliferation provides information on the individual cell behaviour that is not available by other methods. Heparin was used as a model substance to analyze its effect on the migration and proliferation of smooth muscle cells. Subcultured smooth muscle cells were videotaped for 48-72 hours and the interdivision times of all cells were determined. The motility of the cells was quantitated using a morphometric system. While untreated smooth muscle cell clones showed average interdivision times of 14-20 hours, 100 micrograms/ml heparin elongated the interdivision times of about 40% of the clones to average interdivision times of 20-26 hours. While untreated smooth muscle cells showed motility rates ranging up to 45 microns/h, heparin reduced the motility of 90% of the cells to migration rates of 0-15 microns/h. These data indicate a heterogeneous reactivity of different smooth muscle cell subpopulations with respect to heparin effects on migration and proliferation.

Animals↗

PubMed1995

Determination of resting free calcium in barnacle muscle using modified aequorins, buffered calcium injections, and simultaneous image-intensified video microscopy.

Knowing the resting free calcium is important in understanding the role of calcium as an intracellular second messenger. We used a bracketing (null) technique with a luminescent calcium indicator, aequorin, microinjection and image-intensification to measure free calcium in single muscle fibres from the barnacle, Balanus nubilus. We injected modified aequorins (recombinant, and hch-) which after a 30 min diffusion gave reasonable resting glows. Subsequent injection of calcium (strongly buffered with either EGTA or BAPTA, 10 mM) increased or decreased the resting glow depending on the free calcium level in the injected buffer solution. This bracketing (null) method is inherently accurate, but mechanical artifacts on calcium injection reduce the accuracy when total light emission is measured. We therefore used image-intensified video-microscopy of the injected region and video processing (Image-1) of artifact-free regions, to greatly improve the consistency. The luminescence in a pre-selected region of the muscle fibre was measured as a function of time during the injection. Solution calciums were chosen so that if the first injection decreased the resting glow, the second increased it, or vice versa, thus bracketing the true resting value. We used two methods to determine the true value bracketed by our injections: (1) a linear interpolation using the fractional changes in luminescence or (2) a power law interpolation assuming a 2.2 or 2.5 power relationship between luminescence and free calcium. Using these methods, we estimated the free calcium level in the lateral depressor fibres of freshly dredged barnacles to be 279 +/- 36 nM (+/- SD), 339 +/- 42 nM, or 352 +/- 45 nM for the linear, 2.2 and 2.5 powers respectively under the conditions of hch-aequorin and BAPTA buffers (using a K'Ca for BAPTA of 3.0 x 10(6) M-1 for our conditions). Recombinant-aequorin gave essentially the same result while EGTA buffers yielded a somewhat higher value but because of influences of pH on the K'Ca for EGTA (taken as 6.7 x 10(6) M-1 for our conditions) was considered less reliable. Minor changes in [Mg2+] upon buffer injection can lead to underestimates of the true resting [Ca2+] by at most 10%. Thus, we estimate the resting free calcium in barnacle muscle fibres to be 300-380 nM.

Aequorin↗

PubMed1988

Detection of surface movements on single smooth muscle cells: digital video microscopy.

The shortening response of isolated single smooth muscle cells from the toad stomach "Bufo marinus", was studied using digital video microscopy. A computer program was developed to rapidly on-line digitize and store successive video images of the cell as it shortened. Single smooth muscle cells were decorated with tiny anionic exchange resin beads which served as markers for surface motion. Through an interactive software routine, the cell's outline and bead images were defined. Given this information, the program determined the beads location along the length of the cell as well as its angular position on the cell surface. The program allowed the investigator to reconstruct three dimensional images of the cell during contraction. Analysis of successive cell images revealed that during cell shortening, beads would rotate on the cell surface. These data were interpreted as evidence for corkscrew-like shortening in single smooth muscle cells.

Animals↗

PubMed1993

Patch-clamp recordings from the soma and dendrites of neurons in brain slices using infrared video microscopy.

A description is given of the implementation of infrared differential interference contrast (IR-DIC) video microscopy to an upright compound microscope. Using the improved resolution offered by IR-DIC a procedure is described for making patch-pipette recordings from visually identified neuronal somata and dendrites in brain slices. As an example of the application of this technique to electrophysiological recordings from small neuronal processes in brain slices we describe whole-cell current-clamp and cell-attached and excised patch-clamp recordings from the apical dendrites of layer V pyramidal neurons in slices of rat neocortex.

Animals↗

PubMed1990

Characterization of low-light-level cameras for digitized video microscopy.

The use of low-light-level video cameras and solid-state image detectors in conjunction with image digitizers for optical microscopy is increasing dramatically as more people learn about such systems, and as they become more powerful, less expensive, and easier to use. However, there is currently little information available allowing comparison between cameras, or for determining camera suitability for a given experiment. In this paper, we describe a series of tests designed to characterize the performance of low-light-level cameras. The results of these tests should assist in the selection of appropriate cameras for given video microscopy applications.

Image Processing, Computer-Assisted↗

PubMed1992

Epifluorescent video microscopy (EVM) for platelet-biomaterial interactions: elimination of photoactivation and dye effects.

The use of two intracellular dyes for epifluorescent video microscopy (EVM) in observations of cell-surface interactions is evaluated and discussed. This methodology permits determinations of cell adhesion, detachment and movement at the surfaces of biomaterials in the presence of flow and physiological haematocrit. Two tests, one which examines for the effect of incident light on platelet adhesion and one which checks for sufficient light for accurate observation of cells, have been designed. Evaluations were made of the adhesion of platelets labelled with the fluorescent dyes mepacrine and acridine orange, used singly and in combination. The use of a number of light level-dye level combinations with glass and several polymers and the addition of a plasma level of fibrinogen did not show any photoactivation effects. This methodology paves the way for longer than previous exposures to light with our system, from 1 min up to 30 min now. Washed platelet suspensions are preferred; these allow for the selective labelling of specific cells and the removal of dye from the surface of the cell.

Acridine Orange↗