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PubMed1990

[Development of the method of ultrasound topometry of the thyroid gland and computer programs in the planning of radioactive iodine therapy].

The paper is concerned with the problem of stereological volumenometry applied to the problems of ultrasound topometry of the thyroid. The organ surfaces are tightened on the basis of information obtained from echotomographic films using a method of cubic spline-interpolation, parametric function setting and methods of computer graphics. Images of sections can be obtained with an arbitrary step and an angle of inclination to the organ longitudinal axis. The main sources of errors of the method were estimated, and their numeric values were given.

Algorithms↗
PubMed1993

Extracting prototypical facial images from exemplars.

A computer graphic method for extracting a natural image of an individual's facial prototype, or average appearance, from a number of different images of that individual is presented. The process improves upon previous photographic and computational techniques. Synthesis of a person's average expression and pose from a sample of images is derived in an automatic and quantitative way. Possible uses of composite faces produced in this manner in psychological investigations of facial qualities (eg attractiveness) and in applied areas such as telecommunication are pointed out.

Attention↗
PubMed1994

Computer-assisted restriction mapping: an integrated approach to handling experimental uncertainty.

Building a map of restriction sites from double-digest gel data can be a complex and frustrating task, especially when many DNA fragments are detected or when the gel results are ambiguous. 'Double Digester' is an interactive, graphical computer program which helps researchers understand and resolve such data. It explicitly represents the experimental data, the associated uncertainties, the researcher's hypotheses and possible map interpretations. Alternative solutions are frequently possible, and the differences between them may help determine which additional experiments might resolve ambiguities. Initial use has confirmed the benefits of this approach, and has suggested ways in which it can be refined and extended. Double Digester meets the need for a practical tool to help build restriction maps, and also illustrates how a computer-based tool can confront experimental uncertainty in an integrated fashion.

Algorithms↗
PubMedDate not supplied

Image analysis and quantification of atherosclerosis using MRI.

This paper describes an image processing, pattern recognition, and computer graphics system for the noninvasive identification and evaluation of atherosclerosis using multidimensional Magnetic Resonance Imaging (MRI). Particular emphasis has been placed on the problem of developing a pattern recognition system for noninvasively identifying the different plaque classes involved in atherosclerosis using minimal a priori information. This pattern recognition technique involves an extension of the ISODATA clustering algorithm to include an information theoretic criterion (Consistent Akaike Information Criterion) to provide a measure of the fit of the cluster composition at a particular iteration to the actual data. A rapid 3-D display system is also described for the simultaneous display of multiple data classes resulting from the tissue identification process. This work demonstrates the feasibility of developing a "high information content" display which will aid in the diagnosis and analysis of the atherosclerotic disease process. Such capability will permit detailed and quantitative studies to assess the effectiveness of therapies, such as drug, exercise, and dietary regimens.

Algorithms↗
PubMed1990

Medicinal chemistry: a support or a driving force in drug research?

The foregoing has demonstrated most emphatically the significant and central role which chemistry plays in modern and future drug research. It does not mean to diminish the important role of biology but it does serve to show that chemistry is not merely a support for the needs of biology but is a powerful driving force in itself. The two disciplines are essentially interdependent and each relies on the other for success in drug design, discovery and eventual delivery of a useful medicament to the patient. Finally, the medicinal chemist today is faced with as many if not more formidable challenges in medicinal research as his counterpart of a generation ago. The sciences of genetics, molecular biology, neuro-pharmacology and electrophysiology have expanded the knowledge base of cellular function many fold. This new knowledge when coupled with the fundamental role of biochemistry in outlining in chemical terms both normal and abnormal cellular events offers the researcher a much more sophisticated appreciation of the cause of disease states. Knowing which enzymes or receptors are involved is a crucial step towards correcting the malfunctioning cellular conditions. With powerful new methods for determining the three-dimensional structure of molecules and computer graphics which give insight on rational drug design and modification, the medicinal chemist can explore with greater confidence than ever before the road to new drugs. The new biology, the new physical methodology and the computer have enhanced the role of chemistry in modern drug research and have given the medicinal chemist a more profound grasp of cellular aberrations leading to disease. This knowledge is a golden rod in the hands of an imaginative chemist in the search of innovative drugs.

Biochemical Phenomena↗
PubMedDate not supplied

Fabrication of total-contact burn masks by use of human body topography and computer-aided design and manufacturing.

Total-contact burn masks are used to treat scar tissue hypertrophy of the face. The mask should conform very closely to the contours of the face and provide evenly distributed pressure. The mask is worn continually throughout wound maturation. Lack of fit because of an inability to obtain exact facial contours by use of an alginate material diminishes the effectiveness of the mask. A multidisciplinary team representing physical therapy, CAD/CAM (computer-aided design and computer-aided manufacturing), biomedical engineering, and prosthetics has advanced the method of developing total-contact burn masks by use of human body electronic imaging, computer graphics, and numerically controlled milling processes. High-resolution surface scanning and CAD/CAM have been used successfully to accurately fabricate three such masks. The methodology and preliminary results from use of these state-of-the-art techniques are described in this article.

Burns↗
PubMed1998

The application of volume deformation to three-dimensional facial reconstruction: a comparison with previous techniques.

Facial reconstruction has been widely criticised for its subjective nature and is thus often viewed as a last resort. Recent computer-aided reconstructions, which claim to be objective, may be subject to similar errors. To date, both manual reconstructions and computer-aided techniques have been limited to using the same tissue depth data reference tables. We propose that it is not solely the accuracy of the soft tissue depth data, but the sparsity of landmarks, which contributes to a lack of understanding of how soft tissue changes between the landmarks. The authors feel that a new approach to facial reconstruction using a computer graphics technique known as volume deformation addresses some of the problems encountered in the past. A review of previous methods is provided with discussion of the strengths and limitations of these techniques. In addition, areas are highlighted where the new deformation-based approach may offer possible solutions.

Computer Graphics↗
PubMed1988

A model for hormone receptor binding to the mouse mammary tumour virus regulatory element based on hydroxyl radical footprinting.

The mouse mammary tumour virus long terminal repeat region contains regulatory sequences able to mediate transcriptional induction by different steroid hormones. Two clusters of binding sites for the glucocorticoid and the progesterone receptors have been identified in the region between -70 and -190, the so called hormone responsive or regulatory element. To understand the molecular details of the interaction between the receptors and the DNA we have used the high resolution technique of hydroxyl radical footprinting. Both in the promoter distal site and in the promoter proximal cluster additional contacts between the proteins and the double helix are detected by this technique, outside of the region identified by methylation protection. The pattern of contacts in the promoter distal region is compatible with a model involving the interaction of a receptor dimer with the major grooves of four subsequent turns of the double helix, each turn being contacted by a separate zinc finger. This model is illustrated by computer graphical methods and discussed in terms of sequence homologies with other hormone regulatory elements.

Animals↗
PubMed1993

Computer-generated slide graphics: an exciting advancement or a problem?

Computer-generated slide graphics have significantly altered the face of audiovisual presentations. However, it remains to be determined if dramatic effects enhance presentation clarity and increase information retrieval. This study compared color combination and print type graphics. Ninety medical students were shown a 29-minute, 45-slide presentation addressing aspects of plastic surgery. Each slide represented one of 15 color combinations and one of 3 fonts. The students studied each slide for 10 seconds and then in 25 seconds recorded all information they could recall. Statistical analysis (using ANOVA) revealed a significant difference in information retrieval among slides and a significant interaction between color and font. The "best" was orange block print on a raspberry background. The "worst" was yellow cursive print on a black background. This study demonstrated that (1) color influences information gleaned from a slide presentation and (2) font type simplicity may result in improved retention.

Audiovisual Aids↗
PubMed1993

Quantitative three-dimensional assessment of face-lift with an optical facial surface scanner.

Three-dimensional computed tomographic scan images of facial deformities provide information that has been useful in planning and evaluating therapy. However, the benefits of computed tomographic imaging in cosmetic plastic surgery are often insufficient to justify exposing the patient to radiation. This report describes application of an optical, noncontact, three-dimensional surface digitizer with subsecond scanning time for 360-degree examination of the human head. The resultant three-dimensional surface data are suitable for computer graphics display and manipulation, and for noncontact skin surface measurement. The scanner provides accurate and complete coverage of complex facial surfaces. This system was applied to digitization of the human head in the planning and evaluation of facial plastic surgery. The results indicate that the resulting image is accurate enough to detect subtle dimensional changes resulting from surgery, including postoperative edema and surface changes due to face-lift. This type of scanning can assist in a number of tasks performed by plastic surgeons, including collecting anthropomorphic measurements, preoperative and postoperative assessment, volume monitoring, customizing of implants, and interactive planning.

Algorithms↗
PubMed1998

Virtual reality: preparation and execution of sinus surgery.

Endonasal sinus surgery requires a great deal of training before it can be performed adequately. Due to the complex and variable anatomy and the proximity of important structures, severe complications are possible, even for experienced surgeons. The nasal endoscopy simulator (NES) is an interactive training system for nasal endoscopy and endonasal sinus surgery that combines computer graphics and virtual reality (VR) techniques. This system consists of a graphics workstation, a tracking system for measuring the position of the endoscope and surgical instruments in space, a head model, image data sets of the nasal cavity and paranasal sinus area, and complementary software. The current NES is a visual and auditory VR system that provides both educational and planning options for sinus surgery. The usual resistance when touching relevant anatomical structures is not provided by this release. Therefore, a "force feedback system" is implemented that allows for such a response. VR simulation will become an important part of surgical education and planning for individual sinus surgery procedures. The ongoing development of the NES will lead to an improved educational environment for residents in training and practitioners.

Computer Graphics↗
PubMed1995

Three-dimensional analysis of the intrinsic cardiac ganglia in a young dog.

The intrinsic ganglia of the heart of a young dog were studied by computer graphic reconstruction to determine the accurate location. The heart was embedded in celloidin, and transverse sections were cut. Using every third 60 microns section, a series of 49 sections was mapped. Three-dimensional (3D) images were constructed by a personal computer. Numerous intrinsic ganglia, most of which were located in the epicardiun, were observed. The intrinsic ganglia were found in the base of the aorta and pulmonary vessels and from the base of the superior vena cava to the right atrium, i.e., the sinoatrial nodal region. Using the 3D reconstruction technique, the locations of the intrinsic ganglia could be accurately identified. Furthermore, it was demonstrated that these ganglia formed several groups which formed a continuity. This study suggested that it was necessary to consider the existence of the numerous intrinsic ganglia, when we studied the cardiac innervation.

Animals↗
PubMed1994

Characterization of the glycosylation status of proteins.

Proteins are posttranslationally modified by a number of mechanisms, by far the most significant of which in terms of the molecular mass and functional diversity is glycosylation. The oligosaccharide chains added shortly after biosynthesis at the ribosome, and further modified while the protein is translocated through the intracellular membranes, have multiple affects on transport, localization, stability, plasma membrane expression activity, and antigenicity. Characterization of the glycosylation patterns at each site around the protein is essential for detailed understanding of structure/function relationships and the design of potential therapeutic agents. This can be achieved by a series of chromatographic and physicochemical procedures including HPLC, GC, MS, NMR, and computer graphics molecular modeling, which culminate in information on monosaccharide sequence and linkage, glycoprotein conformation, and oligosaccharide-to-protein interactions.

Carbohydrate Conformation↗
PubMed1994

DNurbs: DNA modeled with NURBS.

DNurbs (dee-in-urbs) are a small number of bicubic patches wrapping each base pair in complementary DNA. NURBS, the nonuniform rational B-spline surfaces now popular in computer graphics, are employed for the patches. Control points for the surface patches are generated from the molecular surface based on canonical base pairs.

Base Sequence↗
PubMed1988

Synthetic amphiphilic peptide models for protein ion channels.

Ion channel proteins are important for the conduction of ions across biological membranes. Recent analyses of their sequences have suggested that they are composed of bundles of alpha-helices that associate to form ion-conducting channels. To gain insight into the mechanisms by which alpha-helices can aggregate and conduct ions, three model peptides containing only leucine and serine residues were synthesized and characterized. A 21-residue peptide, H2N-(Leu-Ser-Ser-Leu-Leu-Ser-Leu)3-CONH2, which was designed to be a membrane-spanning amphiphilic alpha-helix, formed well-defined ion channels with ion permeability and lifetime characteristics resembling the acetylcholine receptor. In contrast, a 14-residue version of this peptide, which was too short to span the phospolipid bilayer as an alpha-helix, failed to form discrete, stable channels. A third peptide, H2N-(Leu-Ser-Leu-Leu-Leu-Ser-Leu)3-CONH2, in which one serine per heptad repeat was replaced by leucine, produced proton-selective channels. Computer graphics and energy minimization were used to create molecular models that were consistent with the observed properties of the channels.

Computer Graphics↗
PubMed1993

Human basal ganglia volume asymmetries on magnetic resonance images.

The brains of 19 healthy adults, ages 18-49, were imaged on a GE Signa 1.5 T MR scanner. Basal ganglia were circumscribed on sequential axial proton density-weighted images (TR 1700, TE 20) and submitted for 3-dimensional reconstruction and volumetric analysis at a computer graphics workstation. The 15 right-handed patients (12 men, 3 women) had significantly larger left total basal ganglia volumes, which included larger globus pallidus and lenticular nuclei on the left, but larger caudate nuclei on the right. In contrast, basal ganglia asymmetries were not seen in four left-handers. No sex differences were detected. The basal ganglia appear to belong to an increasing number of CNS structures that display anatomical hemispheric lateralization.

Adult↗
PubMed1987

Landmark identification in computerized posteroanterior cephalometrics.

A lack of cognition regarding the reliability of landmark identification in posteroanterior cephalometrics keeps the extracted data questionable. The present study was designed to analyze this problem for the purpose of providing certain insights. An interactive computer graphic package was developed. This package was called EA-PAX (Error Analysis of Postero-Anterior cephalometric X-ray films). A random sample of 40 clear posteroanterior cephalometric head plates was studied. The reliability of landmark identification was established. The skeletal landmarks seemed more reliable than the dental landmarks. The variation in the direction and magnitude of the error was determined for each landmark. Most landmarks had their own characteristic noncircular envelope of error. It is not the philosophy of the present authors to tell the orthodontists what to use. Rather, the philosophy is to be aware of the amount and direction of variation for a particular landmark. Taking this into consideration will enable the orthodontists to look on their cephalometric numbers with a mental awareness of the possible variations. Several clinical and research studies are suggested in the article.

Adolescent↗