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At least 163 records · Page 9Linked to original sources
PubMed1990

Fluorescent video-microscopy study of regulatory volume decrease in primary culture of rabbit proximal convoluted tubule.

The ability of proximal convoluted tubules in primary culture to regulate volume after a hypotonic shock was investigated by a method based on the use of a fluorescent intracellular probe, (2,7-bis(carboxyethyl)-5,6-carboxyfluorescein: BCECF/AM). The fluorescent signal emitted by the trapped dye excited at 450 nm and analyzed by a video-microscopic set was used to measure the relative volume change. At this wavelength the pH indicator, BCECF, was pH-insensitive and the fluorescent signal related only to the intracellular dye concentration and reflected the variations of the cellular volume as calculated from calibration data. We first determined the fading characteristics of the probe. Second, we characterized the mechanism of regulatory volume decrease (RVD) in primary cultures. RVD occurred 1 min after hypotonic shock and was complete by 4 min. This process was blocked in the presence of barium and scorpion venom (Leiurus quinquestriatus Hebraeus). In the same way, lack of chloride in external medium inhibited RVD. The Cl- blocker 5-nitro-2-(3-phenylpropylamino)benzoic acid (NPPB) at 1.10(-5) M also blocked the regulation. We conclude that RVD in primary cultures of rabbit proximal convoluted tubules involves the stimulation of a potassium conductance via the Ca2(+)-activated maxi K+ channel and that the accompanying anion is chloride via a conductive pathway and (or) a KCl cotransport.

Animals↗
PubMedDate not supplied

Local macromolecular extravasation in thermal burns quantified by fluorescent video microscopy and computer vision.

A dorsal skin flap chamber model was developed for analysis of the microvascular response to moderate intensity local thermal burns. Fluorescein isothiocyanate tagged 70,000 d dextran was introduced to visualize the extravasation and interstitial transport of macromolecules at the burn site. Contact burns 0.5 cm in diameter were affected by touching a thermostated metal rod onto the exposed epidermal side of the chamber preparation. All burns were of 5-second duration at temperatures between 55 degrees C and 70 degrees C. Postburn leakage of the fluorescein-labeled probed was monitored at numerous sites in the preparation on a fluorescent microscope equipped with a low-light-level intensified silicon intensified target video camera and recorded on tape for subsequent quantitative analysis. Selected scenes were digitized and subjected to a sequence of computer-image processing operations to extract quantitative information about the concentration distribution and net accumulation of dextran in the interstitial space as a function of postburn time. A diffusion model based on cylindrical geometry was fit to the concentration profile data at each site analyzed, and an apparent diffusion coefficient describing the interstitial transport process was determined. The interstitial transport increased with burn temperature up to a threshold of 70 degrees C, where other factors resulted in significant reduction in the loss of fluorescent macromolecule from the vasculature.

Animals↗
PubMed1992

Nailfold microcirculation in normotensive and essential hypertensive subjects, as assessed by video-microscopy.

OBJECTIVE: To compare morphological and hemodynamic parameters of skin microcirculation in the fingertip in patients with essential hypertension and normotensive control subjects. DESIGN: Consecutive sample of patients. METHODS: Digital capillary blood flow measurements under normal and cooled conditions were assessed by nailfold video capillaroscopy using the technique of flying spot. RESULTS: There was a significant reduction in capillary density in hypertensive patients, compared with normotensive subjects. There was a correlation between capillary density and mean diastolic blood pressure. After local cooling the frequency of the blood flow stop was significantly higher in hypertensive patients. CONCLUSION: The finding of abnormal vasoconstriction in finger microcirculation in essential hypertension suggests a vasospastic tendency in the disease.

Blood Flow Velocity↗
PubMed1981

Computer-enhanced video microscopy: digitally processed microscope images can be produced in real time.

Digital processing techniques can be used to greatly enhance the available information in an optical image. Although this technology has been routinely used in many fields for a number of years, little application of digital image-processing techniques have been made toward analysis and enhancement of the types of images seen most often by the research biologist. We describe here a computer-based video microscope system that is capable of performing extensive manipulation and enhancement of microscope images in real time. The types of manipulations possible with these techniques greatly surpass the enhancement capabilities of photographic or video techniques alone. The speed and flexibility of this system enables experimental manipulation of the microscopic specimen based on its live processed image. These features greatly extend the power and versatility of the light microscope.

Animals↗
PubMed1997

Immunocytochemical analysis of cisplatin-induced platinum-DNA adducts with double-fluorescence video microscopy.

To detect low-level DNA platination, a sensitive immunocyto- and histochemical technique was developed using a polyclonal antibody. The antibody GPt, derived after immunization of rabbits with highly platinated DNA and purified with affinity chromatography, detected the main platinum (Pt)-containing intrastrand and interstrand adducts. Double-fluorescence microscopy image analysis was used to quantify Pt-DNA adducts with Hoechst 33258 fluorescence to locate the nuclei and with fluorescein isothiocyanate fluorescence to measure the immunosignal. A two- to five-fold dose-dependent difference in the level of cisplatin (CDDP)-induced Pt-DNA adducts between a CDDP-sensitive and -resistant human tumour cell line was detected. Large differences in Pt-DNA adduct levels after in vitro CDDP incubation between human buccal cells, lymphocytes and biopsies of different tumour types were observed. Pt-DNA adduct levels were fivefold higher in human testicular tumours than in colon tumours, representing CDDP-sensitive and -resistant tumours, respectively, in the clinic. These data suggest the possibility of predictive testing by measuring Pt-DNA adduct levels. Pt-DNA adducts in patients after treatment with CDDP were shown in normal buccal cells and in imprints of fresh tumour biopsies as well as in paraffin-embedded tumour cells. The analysis of Pt-DNA adducts at a single-cell level in small samples of normal and tumour cells during and/or after treatment is feasible with GPt and will hopefully enable more selective treatment of patients.

Animals↗
PubMed1985

Video microscopy of fast axonal transport in extruded axoplasm: a new model for study of molecular mechanisms.

The development of AVEC-DIC microscopy and the application of this method to the study of fast axonal transport in isolated axoplasm extruded from the giant axon of the squid Loligo pealei provides a new paradigm for analyzing the intracellular transport of membranous organelles. The size of the axon, the number of transported particles, and the absence of permeability barriers like the plasma membrane in this preparation permit many experiments that are difficult or impossible to perform using other model systems. The use and features of this preparation are described in detail and a number of properties are evaluated for the first time. The process of extrusion is characterized. Particle movement is evaluated both in the interior of extruded axoplasm and along individual fibrils that extend from the periphery of perfused axoplasm. The role of divalent cations, particularly Ca2+, and the effects of elevated Ca2+ on axoplasmic organization and transport are analyzed. A series of pharmacological agents and polypeptides that alter cytoskeletal organization are used to examine the role of microfilaments and microtubules in fast transport. Finally, the effects of depleting ATP and of adding ATP analogues are discussed. The extruded axoplasm preparation is shown to be an invaluable model system for biochemical and pharmacological analyses of the molecular mechanisms of intracellular transport.

Adenosine Triphosphate↗
PubMed1991

Quantitative video microscopy of patch clamped membranes stress, strain, capacitance, and stretch channel activation.

Membrane patches from chick skeletal muscle were stretched by applying controlled suction or pressure to the pipette. From images of the patch, the patch dimensions (area and radius of curvature) were computed by nonlinear regression of the images to a geometric model. With no applied pressure, patch membranes are nearly planar and normal to the wall of the pipette. With increasing pressure gradients, the patch bulges, the radius of curvature decreases, and the area increases. The patch capacitance changes in exact proportion to the change in area at a rate of 0.7 microF/cm2. The increase in area is due to a flow of lipid (with perhaps small amounts of diffusible protein) along the walls of the pipette into the patch. The flow is reversible with a relaxation of the pressure gradient. The area elastic constant of the membrane is approximately 50 dyn/cm, insensitive to cytochalasin B and probably represents the elasticity of the underlying spectrin/dystrophin network. Simultaneous measurements of stretch activated (SA) ion channel activity in the patch showed that the sensitivity of channels from different patches, although different when calculated as a function of applied pressure, was the same when calculated as a function of tension. Because patch lipid is free to flow, and hence stress-free in the steady state, SA channels must be activated by tension in the cytoskeleton.

Animals↗
PubMed1997

Cold-induced acral vasospasm in migraine as assessed by nailfold video-microscopy: prevalence and response to migraine prophylaxis.

In order to learn the prevalence of cold-induced vasospasm in migraine patients, blood cell velocity measurements of finger nailfold capillaries were performed in 58 consecutive patients suffering from migraine with and without aura. In 5 (8.6%) patients capillaroscopy could not be performed because of reduced nailfold transparency; 21 of the remaining 53 patients (39.6%) showed blood flow stop due to vasospasm under cold provocation. There was no significant difference (P = 0.69) in the occurrence of vasospastic reaction between migraine with (12 of 32 patients = 37.5%) and without (9 of 21 patients = 42.9%) aura. The clinical and capillaroscopic course under migraine prophylaxis was observed in 18 vasospastic patients. After sixteen weeks 14 patients showed good clinical improvement of their migraine. The vasospastic reaction persisted in only 1 patient. This patient and 3 others with abolished vasospasm were still suffering from migraine. These findings suggest that observing blood cell velocity noninvasively in nailfold capillaries under cold provocation could be useful for objectively monitoring the response to prophylactic treatment in migraine patients or for testing new potentially antimigraine drugs.

Adult↗
PubMed1996

Regeneration of sensory cells after laser ablation in the lateral line system: hair cell lineage and macrophage behavior revealed by time-lapse video microscopy.

The regeneration of sensory hair cells in lateral line neuromasts of axolotls was investigated via nearly continuous time-lapse microscopic observation after all preexisting hair cells were killed by a laser microbeam. The laser treatments left neuromasts with one resident cell type, which was supporting cells. Over the course of 1 week, replacement hair cells arose either directly via differentiation of cells present in the epithelium from the beginning of the time-lapse period or via the development of cells produced after one or two divisions of supporting cells. All of the cell divisions that produced hair cells were asymmetrical. During the first hour after the treatment, macrophages and smaller leukocytes were attracted to the laser-treated neuromasts. The smaller leukocytes returned to control levels 48-60 hr after the treatment, whereas macrophages remained active there throughout the period of hair cell replacement. Macrophage incidence peaked 36-48 hr after the laser treatment. Macrophages phagocytosed damaged hair cells and supporting cells, as well as new cells and preexisting cells without recognizable damage. The results provide direct evidence of hair cells arising as progeny produced from the divisions of supporting cells, evidence of hair cells and supporting cells arising from the same cell division, evidence relating to the timing of hair cell differentiation, and indirect evidence pertaining to proposals that hair cells sometimes arise via conversion of cells without an intervening division. The results also suggest that macrophages may influence early stages in the process of hair cell regeneration.

Ambystoma↗