Video Imaging System Research Articles

Quantification of image persistence in a digital angiography system

Image persistence, as a characteristic of video imaging systems affecting the quality of fast moving fluoroscopic images, is shown to vary considerably. A simple quantitative method for measuring image persistence in a digital angiography system is presented, together with a series of image intensifier exposure-response curves. For the Saticon tube, used with the Siemens 3VA Digitron, it was found that persistence increased for low exposure rates and may increase to 31% at a 120 ms interval. In addition, a sharp increase in image persistence, from 8.3% to 33%, was observed within 18 months from installation of the system.

Strains in the articular disk of the triangular fibrocartilage complex: A biomechanical study

The articular disk of the triangular fibrocartilage complex was studied using a video imaging system in a cadaveric laboratory experiment. Changes in disk configuration consistently occurred during pronation and supination and resulted in a nonuniform strain distribution that was dependent upon foream position. Strains occurred primarily in the radioulnar axis of the disk, with dorsoanterior strains being negligible. Strains were concentrated in the radial portion of the disk and were highest with the foream pronated. Application of a distraction load to the distal radioulnar joint to simulate the effect of axial wrist loading caused strains to increase the most in the radial portion. These findings suggest that joint distraction loading and forearm pronation are important components of the injury mechanism for the most common type of traumatic tear that occurs near the radial attachment of the disk.

Wrist and hand injuries in platform diving

To permit a smooth entry into the water, platform divers assume a special position with their hands. An older method consists of hitting the water with both fists closed while holding one thumb in the palm of the other hand. In a newer technique fingers and wrists are hyperextended, the forearms pronated, and the hands overlapped. In this series of 21 divers, the injuries included 2 fractures and 5 sprains treated by conservative methods. Two divers required surgery: one with loose bodies in the radiocarpal articulation, the other with chronic rupture of the trapeziometacarpal ligament and synovitis of both extensor pollicis brevis and longus. Eighteen divers complained of pain caused by the impact of the hand with the water. A kinetic analysis with a video imaging system explains the mechanism and forces of water penetration.

An inexpensive, easy to use video imaging system for intracellular Ca2+ and quantitative fluorescence microscopy

Fura-2 is the most commonly used member of a family of calcium sensitive flourescent dyes that allows the measurement of intracellular free calcium (Cai by dual excitation fluorimetry. The use of this dye in conjunction with video imaging microscopy permits visualization of changes in Cai with a high degree of spatial resolution. This resolution in turn allows the detection of Cai gradients, waves, and other localized cellular responses not easily detected by photometric techniques. Despite these advantages, most published reports have utilized photometry rather than imaging, due largely to the higher cost and greater complexity of use of the latter technique. With these problems in mind, we have developed a turnkey calcium imaging system that is both inexpensive and simple enough to use that it can be mastered in 2-3 hours.Data showing the distribution of free Ca2+ in the cytoplasm of a quiescent human fibroblast and the kinetics of stimulation of these cells with mitogens are illustrated on the next page.

A spherical model analyzing shoulder motion in overhand and sidearm pitching

An accurate measurement of shoulder movement in pitching is indispensable in clarifying the causes of shoulder problems stemming from baseball pitching and in preventing these disorders. In this investigation, three-dimensional imaging and electromyography were performed during pitching. Two different pitching methods (overhand throwing and sidearm throwing) of 35 amateur pitchers were analyzed with a high-speed video imaging system. In 25 subjects shoulder rotation during pitching was measured with a compact camera attached to the shoulder. In 21 subjects, the electromyographic activity of the biceps and triceps muscles during pitching was examined. Image analysis showed little difference in shoulder movement between the two pitching methods for each subject, while individual subjects had specific shoulder movements. Electromyography demonstrated the role of the triceps muscle during pitching. The clinical ramifications of these analyses may be very useful.

Sodium channels, GABAA receptors, and glutamate receptors develop sequentially on embryonic rat spinal cord cells

It is not well understood when during embryonic development the elements of a cell's responsiveness first appear, nor the factors controlling their appearance. A strategy to approach this issue is to determine which aspects of neuronal development are highly stereotyped in presence, timing, or pattern across a variety of cell types, and which are more diversified by cell type, region, or other parameters. We have used a fluorescent potentiometric oxonol dye in conjunction with a digital video imaging system to record the emergence and distribution of specific forms of excitability in dissociated embryonic rat spinal cord cells. We studied the expression of responses to veratridine, a sodium channel activator; muscimol, a GABAA receptor agonist; and kainic acid, an agonist at a class of glutamate receptors. Responses were consistently detectable in a percentage of cells dissociated from the earliest age examined, embryonic day 13, and increased progressively in later ages. Cells were examined from four regions, with cervical-lumbosacral and ventrodorsal distinctions. In the population of cells from each region, functional sodium channels appeared prior to GABAA receptors, which in turn emerged prior to kainate-activated glutamate receptors. This pattern was common to all spinal cord regions and revealed ventrodorsal and rostrocaudal gradients reflecting the known pattern of spinal cord neurogenesis. Analysis of the individual cell responses indicated that the stereotypical pattern of sequential channel development occurs individually on most cells in each region.

Visual Documentation

The addition of video co-observation to laparoscopic surgery, with its expanding amalgamation of endoscopic and videoimaging systems, has enables surgeons to pursue more ambitious operative endoscopic undertakings than were previously feasible. This article discusses the benefits of video imaging, perioperative factors, rudimentary optical tenets, equipment, and future directions.

An approach to unbiased sampling of pulmonary structures for morphometric analysis

Abstract In inhalation toxicology, the quantitative estimation of lung structures is important to detect finite effects induced by low concentrations of toxicants. Unbiased sampling of tissues is an essential precondition for morphometric estimation, but the complexity of lung structures makes it difficult to meet this requirement. During the course of an inhalation study on beagle dogs, we developed a method for unbiased sampling of lungs by modifying previous sampling methods. For the morphometric estimation of the surface density in two‐dimensional sections, for example, the structures must be isotropic. The validity of isotropy in airways can be questionable, and the distribution of structural changes in the tissues resulting from pathological processes is generally unpredictable, so that it is essential to apply three‐dimensional uniform sampling (e.g., the vertical section method) for the analysis of possibly anisotropic structures. We modified the vertical section method in order to obtain large (20 × 30 mm) and small (1×1 mm) sections from the same tissue for both light and election microscopy. For the morphometric analysis of the lung structures of large animals and humans, tiered (or cascade) sampling is necessary. Using a laser printer connected to a video image system, samples could be selected at different levels of magnification in a strictly systematic random way. The combination of these modified methods allows unbiased quantitative estimation of both isotropic and anisotropic lung structures. These methods are practical and can be used in large‐scale inhalation studies.

Quantitation of rodent catalepsy by a computer-imaging technique

Catalepsy is usually defined as a behavioral state in which an animal maintains an unnatural posture for an extended period of time. While numerous laboratory models have been developed for assessing catalepsy, a common problem encountered with most procedures is the difficulty in quantitating immobility. Measurement of catalepsy is still frequently subjective in nature. To eliminate this subjectivity, a computer-based technique was developed for quantitating catalepsy in mice and rats as measured on the elevated ring. The system consisted of a videocamera that was focused on either three mice or two rats. Their behavior was recorded during a 5-min session on videotape that was subsequently transmitted to a Macintosh II microcomputer via a Scion Image-Capture 2 board. A modification of the NIH Image 1. 17 public domain program allowed the image of the rat to be transformed to a purely black or white image by assigning pixel values of either 0 or 256. The subsequent captured image was preprocessed in an identical manner and each pixel was subtracted from its corresponding pixel in the previous frame. Thus, changes in animal posture between the two frames can be quantitated. One subtraction cycle (acquisition, bilevel processing, and subtraction) was repeated at an average rate of approximately one per second. To quantitate immobility by image analysis, each frame was subtracted from the previous frame during a 5-min session. The resulting data were sorted according to the magnitude of movement (number of changed pixels) and plotted vs. time. A biphasic plot resulted, showing a clear demarcation between mobility and immobility that could also easily be distinguished from background noise inherent in the video imaging system. Quantitation of the period of immobility in this fashion was found to be in close agreement with that obtained by human observation over a wide range of immobility-inducing drugs.

The velocity and recoil of DNA bands during gel electrophoresis

The velocity and recoil of bands of DNA containing 48.5 to 4800 kilobasepairs (kb) were measured during pulsed-field gel electrophoresis by a video imaging and analysis system. When a 10 V/cm electric field was first applied, the velocity showed an initial sharp peak after approximately 1 s whose amplitude depended on the molecular weight of the DNA and the rest time and polarity of the previous pulse. For example, G DNA (670 kb) exhibited an initial velocity peak of 13 μm/s. The velocity then oscillated through a shallow minimum and small maximum before reaching a 5.0 μm/s plateau. After the field was turned off, the bands moved backward (recoiled). The band position obeyed a stretched-exponential relation, x = x0 exp[ − (t/τ)β] with amplitude x0 equal to approximately 1/10th of the DNA contour length and β≊0.6; for S. pombe DNA, x0 was a remarkable 165 μm. Both the initial velocity spike and the recoil arise from the presence of a significant fraction of U-shaped molecules with low configurational entropy. The initial velocity spike is exploited in field-inversion gel electrophoresis to generate the ‘‘antiresonance,’’ which is the basis of size-dependent mobility. Recent computer simulations which include tube-length fluctuations and tube leakage are in excellent accord with the measured velocities.

A novel circadian phenotype based on firefly luciferase expression in transgenic plants.

A 320-bp fragment of the Arabidopsis cab2 promoter is sufficient to mediate transcriptional regulation by both phytochrome and the circadian clock. We fused this promoter fragment to the firefly luciferase (Luc) gene to create a real-time reporter for regulated gene expression in intact plants. Cab2::Luc transcript accumulated in the expected patterns and luciferase activity was closely correlated to cab2::Luc mRNA abundance in both etiolated and green seedlings. The concentration of the bulk of luciferase protein did not reflect these patterns but maintained a relatively constant level, implying that a post-translational mechanism(s) leads to the high-amplitude regulation of luciferase activity. We used a low-light video imaging system to establish that luciferase bioluminescence in vivo accurately reports the temporal and spatial regulation of cab2 transcription in single seedlings. The unique qualities of the firefly luciferase system allowed us to monitor regulated gene expression in real time in individual multicellular organisms. This noninvasive marker for temporal regulation at the molecular level constitutes a circadian phenotype, which may be used to isolate mutants in the circadian clock.

A method for creating precise low-cost landscape architecture simulations — combining computer-aided design with computer video-imaging techniques

With the ever-growing public involvement in design procedure and policy-making and the demand for more objective presentation of design proposals, traditional simulation methods (drawing, rendering etc.) are increasingly challenged. A good simulation must be accurate both physically and visually. Ordinary computer-aided design (CAD) representations (wire-frame, shaded models) are often questioned for lack of visual accuracy particularly in relation to landscape design. Recent computer video-imaging systems (a range of new techniques used to create and manipulate images captured from video sources using computer hardware and software), offer very high visual precision (photorealistic) but are hampered by their inability to produce physically accurate models. Individually, none of the systems to date can satisfactorily produce simulations with both physical and visual precision. This paper describes a methodology for combining the existing PC-based standard three-dimensional CAD program (AutoCAD) and computer video-imaging techniques for achieving precise landscape simulation. The method is demonstrated on a real urban landscape project.

Fat-storing cells as liver-specific pericytes. Spatial dynamics of agonist-stimulated intracellular calcium transients.

Liver perisinusoidal fat-storing cells (FSC) show morphological and ultrastructural characteristics similar to pericytes regulating local blood flow in other organs. In the present study we have analyzed whether FSC respond to local vasoconstrictors such as thrombin, angiotensin-II, and endothelin-1 with an increase in intracellular free calcium concentration ([Ca2+]i) coupled with effective cell contraction. All agonists tested induced a rapid and dose-dependent increase in [Ca2+]i followed by a sustained phase lasting several minutes in confluent monolayers of Fura-2-loaded human FSC. Pharmacological studies performed using different Ca2+ channel blockers indicated that, at least for thrombin and angiotensin-II, the sustained phase is due to the opening of voltage-sensitive membrane Ca2+ channels. To analyze the temporal and spatial dynamics of Ca2+ release in response to these agonists, we performed experiments on individual Fura-2-loaded human FSC using a dual wavelength, radiometric video imaging system. The rise in [Ca2+]i was exclusively localized to the cytoplasm, particularly in the branching processes. Increases in [Ca2+]i more than four-fold were associated with a simultaneous and transient reduction of cell area indicating reversible cell contraction. Our results indicate that the Ca(2+)-dependent contraction of human FSC in vitro may reflect a potential role in regulating sinusoidal blood flow in vivo.

Simple real-time noise removal in intensified low-light-level television images

A simple and novel real-time interframe operator substantially reduces short-lived noisy scintillations in low-lightlevel video imaging systems that use image intensifiers.

Identification and control of a multizone crystal growth furnace

This paper presents an intelligent adaptive control system for the control of a solid-liquid interface of a crystal while it is growing via directional solidification inside a multizone transparent furnace. The task of the process controller is to establish a user-specified axial temperature profile and to maintain a desirable interface shape. Both single-input-single-output and multi-input-multi-output adaptive pole placement algorithms have been used to control the temperature. We also describe an intelligent measurement system to assess the shape of the crystal while it is growing inside a multizone transparent furnace. A color video imaging system observes the crystal in real time, and determines the position and the shape of the interface. This information is used to evaluate the crystal growth rate, and to analyze the effects of translational velocity and temperature profiles on the shape of the interface. Creation of this knowledge base is the first step to incorporate image processing into furnace control.

Imaging of intracellular calcium in rat anterior pituitary cells in response to growth hormone releasing factor.

1. Changes in intracellular ionized calcium [Ca2+]i induced by human growth hormone releasing factor (hGRF) were analysed by quantitative fluorescent microscopy using a dual-wavelength, ratiometric video imaging system and low light level charge-coupled device (CCD) camera visualizing Fura-2 in dispersed male rat anterior pituitary cells. 2. In cells responding to hGRF, spontaneous basal oscillations in [Ca2+]i were frequently observed, and these were usually characterized by a gradient of [Ca2+]i localized in the subplasmalemmal region of the cell. 3. Of the cells which responded to hGRF, the peptide evoked a rise in [Ca2+]i, especially in the region of the subplasmalemma. Continuous application of 10 nM-hGRF produced several different temporal patterns of the [Ca2+]i response which were not attributable to spatial response profiles. A sustained rise in [Ca2+]i was the most common type of response to hGRF (44% of the cells examined). 4. One-third of the cells responding to 10 nM-hGRF showed spontaneous basal [Ca2+]i oscillations ranging from 100 to 500 nM. Mean values of basal and 10 nM-hGRF-induced [Ca2+]i of these cells were 81 +/- 11 nM (mean +/- S.E.M., n = 27) and 560 +/- 47 nM (n = 27) respectively. There was no significant correlation between basal [Ca2+]i and the hGRF-induced [Ca2+]i increase, nor was there any consistent correlation with regard to the spatial response profile. 5. Application of 2 mM-Co2+ abolished the hGRF-induced rise in [Ca2+]i. Quantitative analysis of this effect, performed by comparing the mean [Ca2+]i evoked during the application of hGRF with and without Co2+, respectively, also showed significant inhibition of the hGRF-induced rise in [Ca2+]i by the application of Co2+ (P less than 0.001). 6. The hGRF-induced rise in [Ca2+]i was completely suppressed by replacing extracellular Na+ with impermeant molecules such as mannitol. The onset and offset of suppression was as rapid as that induced by Co2+. Quantitative analysis showed significant inhibition of the hGRF-induced rise in [Ca2+]i by Na+ replacement (P less than 0.01). 7. Tetrodotoxin, a potent blocker of voltage-sensitive Na+ channels (5 and 20 microM), did not affect the hGRF-induced rise in [Ca2+]i. 8. Extracellular application of the membrane permeable dibutyryl cyclic AMP (DBcAMP) to elevate intracellular levels of cyclic AMP caused a large rise in [Ca2+]i, which was dependent on extracellular Na+ and was abolished by 2 mM-Co2+ applied in the bath.(ABSTRACT TRUNCATED AT 400 WORDS)

The design and clinical application of digital portal imaging systems

The recent introduction of electronic portal imaging devices (EPID’s) opens up new possibilities for verifying the accuracy of radiation treatments, reducing set-up and treatment errors, and ensuring the precise delivery of dose to the prescribed target volume. Various designs are available, based on ionization chambers, solid state detectors, and video imaging systems, and their relative merits are compared with computed radiography and with conventional portal films. The factors influencing portal image quality are discussed in terms of dose utilization, contrast and spatial resolution, temporal response, and digital image processing. Image acquisition and display techniques include localization (pretreatment) and verification (post-treatment) static images, intra-treatment movies, and inter-treatment time-lapse displays.

Epibionts on Chlamys hastata and Chlamys rubida: taphonomic and paleoecologic implications

Although many fossil epibiont assemblages have been described, the taphonomy of these assemblages is poorly understood. In an effort to investigate the percentage of epibiontic organisms that would likely be preserved in the fossil record, and the contemporaneity of epibionts on a particular shell, I investigated the epibionts on live and dead Chlamys hastata and C. rubida from around San Juan Island, Washington. Using a video imaging system, over 300 shell surfaces were examined and the percent covers of epibionts in eight taxonomic categories were calculated.The left (upper) valves of live Chlamys had an average epibiont cover of 75% that was composed primarily of sponge, or a combination of barnacles and sabellid annelids. The preservable portion of this assemblage (18%) was significantly less than that of epibionts on the exteriors (68%) and interiors (87%) of dead valves. On dead shell surfaces, sponge coverage is <1%, and there are higher proportions of cheilostome and cyclostome bryozoans, and serpulid and spirorbid annelids.On upper surfaces (left valves) of living Chlamys, 10% of the epibiont cover was composed of dead organisms. An even greater percentage of dead epibiont cover existed on lower valves of live individuals (25%), and on dead valves (37-47%). During the study, no unambiguous examples of competitive interactions were found except for barnacles overgrowing barnacles and other epibionts. Numerous other overgrowths were observed, but these resulted from growths over dead organisms, or growths over mineralized skeleton, not living tissue.These results suggest that exact contemporaneity between epibionts should not be assumed in paleoecological studies.and that soft bodied and agglutinating organisms may have been important constituents of some paleocommunities. Encrusting epibiontic sponge actually protects shell surface ornamentation and may be evidenced in the fossil record by particularly clean and unfouled shells.

Nuclear calcium gradients in cultured rat hepatocytes

Ca2+ concentrations ([Ca2+]) in cytosol and nucleus in fura-2-loaded cultured rat hepatocytes were determined by three-dimensional (3-D) optical-sectioning microscopy. After determining the empirical 3-D point spread function of the fluorescence microscope-coupled digital video imaging system, contaminating light arising from optical planes above and below the plane of interest was removed by deconvolution using the nearest-neighboring approach (NNA) algorithm. Although deconvolution resulted in substantial improvement in accuracy of fluorescence intensity determinations in single-wavelength excitation images as well as sharper delineation of boundaries between cellular compartments, the complicated mathematical process did not significantly enhance the precision of [Ca2+] values derived from ratiometric (ratio of dual-wavelength excitation) images. In resting hepatocytes, cytosolic Ca2+ (210 +/- 15 nM) was 1.6- to 2-fold higher than nuclear Ca2+ (128 +/- 12 nM). This difference in Ca2+ between the two compartments was detected both in raw ratiometric images and in those processed with NNA algorithm. Addition of arginine vasopressin or epidermal growth factor resulted in significant increases (2- to 3-fold) in both cytosolic and nuclear Ca2+; however, the nuclear-to-cytosolic Ca2+ gradient was preserved in hepatocytes stimulated with mitogens. We conclude that the hepatocyte nuclear membrane contains Ca2+ permeability barriers and Ca2+ transport mechanisms that may be hormonally sensitive. We postulate that the increase in nuclear Ca2+ may be important in regulation of cell proliferation induced by mitogens, possibly by activating Ca(2+)-dependent endonucleases, nuclear calmodulin, or nuclear protein kinase C.

Calcium signals in single T cells on activation by lectin

Succinylation of concanavalin A (Con A) reduces its oligomer size while retaining its mitogenicity, and provides a probe of T cell activation. We have observed responses of cytosolic ionized calcium to succinyl Con A in suspensions of Jurkat and rat lymph node (LN) cells, using a fluorimeter, and in single cells settled on glass, using a dual wavelength video imaging system. In the fluorimeter a mitogenic level of succinyl Con A (30 micrograms/ml) produced only a 15-30 nM rise in average cell calcium in the suspended Jurkat or rat cells whereas the use of quantitative video imaging produced asynchronous 250-1000 nM pulses of free calcium in 35% of Jurkat cells and 300-850 nM pulses in 45% of rat LN cells. In Jurkat cells these pulses were sometimes repetitive, giving rise to apparent oscillations. In the fluorimeter 30 micrograms/ml of native Con A (a supra-mitogenic concentration) produced a 300 nM rise in average cell calcium in suspended Jurkat cells, and a 100 nM rise in rat LN cells; when major histocompatibility complex class II-bearing cells were removed the response rose. Mitogenic Con A (3 micrograms/ml) produced a much lower rise in calcium. With video imaging the response seen was greater. Levels greater than 30 micrograms/ml Con A caused 700-5000 nM pulses synchronously in 94% of Jurkat cells and 250-1000 nM pulses in 73% of rat LN cells. At 3 micrograms/ml Con A produced asynchronous 300-1100 nM pulses in 36% of rat LN cells. We conclude that the absence of a calcium signal in the fluorimeter can conceal asynchronous calcium responses in individual cells and that brief asynchronous cytosolic calcium pulses are sufficient for lectin to activate rat T cells.