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PubMed1990

PEANUT: computer graphics program to represent atomic displacement parameters.

PEANUT is an easy to use computer graphics program for the visualization and real-time manipulation of the atomic displacement parameters of small molecules. A flexible, dynamic data structure allows the user to compute complicated, nonspherical atomic surfaces and to handle the point group symmetry of the molecules automatically. Pictures with hidden-line removal may be plotted in publication quality on appropriate output devices.

Azepines↗
PubMed1995

Visual arithmetic, computational graphics, and the spatial metaphor.

People who interact with graphs to perform arithmetic tasks typically employ quantitative features. However, they may employ the spatial metaphor under two alternative conditions: if they have been trained to apply visual arithmetic methods to traditional line and bar graphs, or if they interact with specially constructed and special-purpose computational graphics. Two experiments explored a visual arithmetic method used to train subjects to determine a mean by locating the spatial midpoint of a set of indicators (bars in a bar graph or points in a line graph). In Experiment 1 visual arithmetic subjects determined the mean of five indicators as quickly as they did the mean of two indicators; control subjects performed slower with five indicators. Both groups took more time to add the values of five indicators than to add two indicators. In Experiment 2, unlike control subjects, visual arithmetic subjects' response times in mean trials were unaffected by changes in the y-axis scale. However, both groups were affected by the y-axis scale on addition trials. Neither group was influenced by changes in the distance between indicators. The discussion addresses the transfer of visual arithmetic training to tasks that differ from the one used during training, uses for visual arithmetic and computational graphics, and the role of parallel processing and task restructuring in visual arithmetic.

Adolescent↗
PubMed1995

Computer graphics of SEM images facilitate recognition of chromosome position in isolated human metaphase plates.

There is general agreement that at the time of mitosis chromosomes occupy precise positions and that these positions likely affect subsequent nuclear function in interphase. However, before such ideas can be investigated in human cells, it is necessary to determine first the precise position of each chromosome with regard to its neighbors. It has occurred to us that stereo images, produced by scanning electron microscopy, of isolated metaphase plates could form the basis whereby these positions could be ascertained. In this paper we describe a computer graphic technique that permits us to keep track of individual chromosomes in a metaphase plate and to compare chromosome positions in different metaphase plates. Moreover, the computer graphics provide permanent, easily manipulated, rapid recall of stored chromosome profiles. These advantages are demonstrated by a comparison of the relative position of group A-specific and groups D- and G-specific chromosomes to the full complement of chromosomes in metaphase plates isolated from a nearly triploid human-derived cell (HeLa S3) to a hypo-diploid human fetal lung cell.

Cells, Cultured↗
PubMedDate not supplied

Three-dimensional demonstration of liver and spleen by a computer graphics technique.

Three-dimensional demonstration of the liver and spleen has been developed using a computer graphics technique. Three-dimensional models were constructed from organ-surface information derived from computed tomographic images. Three-dimensional images could be displayed as wire-frame or solid models on a color display tube. After examining the accuracy of this technique using a liver phantom, this technique was applied to the human liver and spleen. The anatomic surface of the liver and spleen appeared realistic when viewed from any direction. In liver cirrhosis, abnormal configuration of the liver and spleen was vividly demonstrated. The liver was displayed as a wire-frame, while a hepatoma was presented as a solid form in the same image. This combined display clarified the intrahepatic location of the hepatoma together with its configuration. It is thus expected that this technique will prove clinically useful in the noninvasive evaluation of patho-morphologic changes in the liver and spleen.

Adult↗
PubMed1988

Evaluation of densitometry data using interactive computer graphics: application to DNA agarose gels.

A method of analyzing DNA agarose gels using interactive computer graphics is described. After electrophoresis in an alkaline agarose gel, DNA is neutralized, stained with ethidium bromide and excited with ultraviolet radiation. The resulting fluorescent distribution on the gel is photographed, and the negative scanned by a digitizing densitometer. The data is subsequently analyzed using a computer program developed to facilitate manipulation and selection of data from the densitometer trace. The method has been applied to determine pyrimidine dimer yields in DNA from human lymphocytes exposed to UV radiation. The technique significantly reduces the time required to analyze such data, while also providing greater accuracy. The method could be easily adapted to assist in similar analyses of other macromolecules such as RNA or proteins.

Computer Graphics↗
PubMedDate not supplied

[Application of three-dimensional computer graphics in oncology].

Accurate 3D tumoral volume evaluation is now possible through the combined use and progress of computer graphics technics (3D reconstruction and visualization) and medical imagery (helicoidal TDM scanner). Specific organ and pathology oriented softwares can help answer rapidly to problems posed by oncologic praticians. A new decision support for diagnosis, therapy and follow-up is emerging. First results in liver tumors and hepatic regeneration macroscopic biometrics are presented. Tumoral or organ volumic index will be usable in the follow-up. TNM staging, external conformal radiotherapy for prostatic or brain tumors, drugs cytolytic effects evaluation will take great advantage of these technologies. 3D visualization and matching CT and MRI imagery can help computed assisted surgery.

Computer Graphics↗
PubMed1990

High-performance liquid chromatography of amino acids, peptides and proteins. C. Characterisation of coulombic interactive regions on hen lysozyme by high-performance liquid anion-exchange chromatography and computer graphic analysis.

The molecular characteristics of the dominant anion-exchange binding site of hen egg white lysozyme (HEWL) has been investigated using a combination of high-performance liquid chromatographic techniques and computer graphic analysis of the X-ray crystallographic structure. These studies have indicated that the site of highest electrostatic potential, in terms of the density of negatively charged amino acid side chains, is located around the catalytic cleft area. The four residues tentatively identified to be involved in the electrostatic binding domain were aspartic acid 48, 52, 101 and glutamic acid 35. The number of these charged groups correlated with the maximum value of the chromatographically determined retention parameter (Zc value). Variations in the range of experimental Zc values obtained under different elution conditions have been interpreted in terms of conformational flexibility of the structural domains of HEWL which result in the opening or closure of the catalytic cleft during the retention process.

Amino Acid Sequence↗
PubMed1989

The deformity of idiopathic scoliosis made visible by computer graphics.

We present a method of visualising spinal deformities in three dimensions using conventional radiographs and computer graphics. The shape of the spinal column can be determined from the anteroposterior and lateral radiographs and displayed in any projection. In patients with adolescent idiopathic scoliosis, the fundamental lesion, an abnormal lordosis, can be demonstrated without the need for additional views. The method is applicable to other spinal deformities and may help to elucidate their three-dimensional shape.

Adolescent↗
PubMed1989

Computer graphics tools for radiation treatment planning.

The objective of radiation therapy treatment is to eradicate a cancerous tumor while keeping the damage to nearby healthy organs to a minimum. A variety of tools employing computer graphics exist to aid in the planning and verification of treatments. Three-dimensional (3D) image information available from sources such as computerized tomography (CT) scanners is used to define the sizes, shapes, and spatial locations of the tumor and normal structures in the form of transverse contours. These object definitions are displayed in 3D perspective to enable the determination of the best possible directions from which to aim radiation beams at the tumor. The beams may be shaped to match the outline of the tumor, and their intensities may be modified using compensating devices. The results of calculations done to predict the distribution of radiation dose throughout the body due to a given set-up of beams can be displayed to the user in many ways. Dose may be shown in the form of isodose contours overlaid on transverse CT images, or on reconstructed image planes of arbitrary orientation in space. There are also a number of methods of 3D display; dose can be shown on the surface of objects, or in the form of isodose surfaces relative to anatomical structures. Computer-generated beam film images may be used to verify patient set-up and tumor coverage.

Computer Graphics↗
PubMed1986

A computer graphics model of frog gamma-crystallin based on the three-dimensional structure of calf gamma-II crystallin.

Molecular models for Rana gamma-1 and gamma-2 crystallins have been constructed using computer graphics on the basis of the protein primary structure derived from the complementary DNA sequence and the three-dimensional structure of calf gamma-II crystallin that has been defined at high resolution by X-ray analysis. The models show that the cores of the two domains are conserved as hydrophobic, with the polypeptide chain arranged as a four Greek-key motif structure. Although many lysines replace arginines at equivalent positions in mammalian proteins, the Rana crystallins also have an extensive series of ion pairs on their surface; these are strongly implicated in their function as stable structural molecules, which are highly conserved in the evolution of the vertebrate eye lens.

Animals↗
PubMed1995

Situation awareness as a function of frame of reference, computer-graphics eyepoint elevation, and geometric field of view.

The purpose of this study was to determine how 3 variables for the design of a "heads-down" spatial display--the frame of reference (pilot's eye vs. God's eye), geometric field of view, and elevation of the computer graphics eyepoint--influenced situation awareness. Thirteen flight-naive subjects each flew a simulated F-16 over a computer-generated flight environment to lock onto and intercept a series of sequentially appearing targets. The flight scene consisted of both an "out-the-window" view and a computer-generated heads-down spatial display showing an airplane symbol superimposed on a perspective view of the flight environment. During the interactive phase of the experiment, root mean square flight-path error, target lock-on time, and target acquisition time were measured. After the interactive phase of the study was completed, subjects were required to mark the location of the targets from memory on a computer-generated top-down view of the flight scene in an attempt to reconstruct the spatial mental model which subjects formed of the flight environment. The results for the interactive phase of the study indicated that performance was superior using the pilot's-eye display. However, for the spatial reconstruction task, performance was better using the God's-eye display. It was also shown that the ability to maintain the optimal flight-path using the more top-down view of the scene (600 eyepoint) was superior to the 300 eyepoint elevation. Implications of the results for the design of spatial instruments are discussed.

Adult↗
PubMed1989

Colposcopy and computer graphics: a new method?

A new method is herein described that uses the most recent computer science techniques to obtain digitalized colposcopic images that may be useful not only as documents, but also as research tools. Because computer graphics is a recent and ever-growing discipline, our method, too, might undergo considerable improvements: some possible improvements are hypothesized in the text. The most striking features of this method are the excellent quality of images, their easy reproducibility, and the reasonable cost.

Cervix Uteri↗
PubMed1991

Use of computer graphics simulation for teaching of flexible sigmoidoscopy.

The concept of simulation training in endoscopy is now well-established. The systems currently under development employ either computer graphics simulation or interactive video technology; each has its strengths and weaknesses. A flexible sigmoidoscopy training device has been designed which uses graphic routines--such as object oriented programming and double buffering--in entirely new ways. These programming techniques compensate for the limitations of currently available desk-top microcomputers. By boosting existing computer 'horsepower' with next generation coprocessors and sophisticated graphics tools such as intensity interpolation (Gouraud shading), the realism of computer simulation of flexible sigmoidoscopy is being greatly enhanced. The computer program has teaching and scoring capabilities, making it a truly interactive system. Use has been made of this ability to record, grade and store each trainee encounter in computer memory as part of a multi-center, prospective trial of simulation training being conducted currently in the USA. A new input device, a dummy endoscope, has been designed that allows application of variable resistance to the insertion tube. This greatly enhances tactile feedback, such as resistance during looping. If carefully designed trials show that computer simulation is an attractive and effective training tool, it is expected that this technology will evolve rapidly and be made widely available to trainee endoscopists.

Computer Graphics↗
PubMedDate not supplied

Three-dimensional computer graphics of the eustachian tube.

Images of the eustachian tube from various directions were obtained using computer graphics. Serial cross sections of a human temporal bone specimen including the eustachian tube were digitized for reconstruction. Wire-frame models of the structures such as the eustachian tube lumen, the tubal cartilage, the tensor veli palatini muscle, and the levator veli palatini muscle were drawn. Through observation of the eustachian tube from various directions with the tubal muscles attached or detached, the physiology of the eustachian tube system could be understood more clearly.

Cartilage↗
PubMed1996

Development and evaluation of a new 3-D digitization and computer graphic system to study the anatomic tissue and restoration surfaces.

It is necessary to visualize and reconstruct tissue anatomic surfaces accurately for a variety of oral rehabilitation applications such as surface wear characterization and automated fabrication of dental restorations, accuracy of reproduction of impression and die materials, etc. In this investigation, a 3-D digitization and computer-graphic system was developed for surface characterization. The hardware consists of a profiler assembly for digitization in an MTS biomechanical test system with an artificial mouth, an IBM PS/2 computer model 70 for data processing and a Hewlett-Packard laser printer for hardcopy outputs. The software used includes a commercially available Surfer 3-D graphics package, a public domain data-fitting alignment software and an inhouse Pascal program for intercommunication plus some other limited tasks. Surfaces were digitized before and after rotation by angular displacement, the digital data were interpolated by Surfer to provide a data grid and the surfaces were computer graphically reconstructed: Misaligned surfaces were aligned by the data-fitting alignment software under different choices of parameters. The effect of different interpolation parameters (e.g. grid size, method of interpolation) and extent of rotation on the alignment accuracy was determined. The results indicate that improved alignment accuracy results from optimization of interpolation parameters and minimization of the initial misorientation between the digitized surfaces. The method provides important advantages for surface reconstruction and visualization, such as overlay of sequentially generated surfaces and accurate alignment of pairs of surfaces with small misalignment.

Computer Communication Networks↗
PubMed1982

Comparison of the inhibition of Escherichia coli and Lactobacillus casei dihydrofolate reductase by 2,4-diamino-5-(substituted-benzyl)pyrimidines: quantitative structure-activity relationships, X-ray crystallography, and computer graphics in structure-activity analysis.

The inhibition constants (Kiapp) obtained from the action of 44 2,4-diamino-5-(substituted-benzyl)pyrimidines on dihydrofolate reductase (DHFR) from Escherichia coli and Lactobacillus casei bacteria are used to derive quantitative structure-activity relationships (QSAR). These equations bring out a number of differences in the DHFR which can be understood at the atomic level by studying color stereo computer graphics models constructed from the X-ray coordinates of the enzyme-inhibitor complexes. The combination of QSAR and X-ray crystallography interpreted via high-performance computer graphics offers a new level of sophistication to extend our understanding of enzyme-ligand interactions, which, when the crystallography is known, opens up a more scientific approach to drug development.

Binding Sites↗