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Conformational properties of apolipoproteins studied by computer graphics.
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Interactive computer graphic image analysis for functional neurosurgery.
This study deals with the use of microcomputer graphic analysis of preoperative magnetic resonance imaging (MRI) scans in functional neurosurgical procedures. Three patients (2 treated for thalamotomy and 1 for thalamic stimulation) had preadmission MRI scans which delineated the classic internal landmarks used in functional neurosurgery. These data were then manipulated and stored using a microcomputer-based graphic analysis system. Intraoperative pattern matching of preadmission graphics with the intraoperative skull X-rays allowed determination of the planned target in the x, y and z coordinates. The accuracy of the graphics FM-PC and AC-PC points was confirmed with the use of ventriculography, stimulation, and postoperative MRI scans. This simple, inexpensive method obviates the need for ventriculography, sedation, intraoperative MRI with a scan-compatible frame, and has the accuracy necessary for functional procedures.
Morphology of fibroblasts in collagen gels: a study using 400 keV electron microscopy and computer graphics.
We have used 400 kilovolt intermediate voltage electron microscopy (IVEM) to examine thick sections of fibroblasts cultured in collagen gels. In these 3D collagen lattices, the long, narrow pseudopodial extensions that extend out and make contact with the collagen matrix exhibit a complex topography not seen in the processes put out by cells moving on planar substrata. For this reason, sections 1 to 2 microns thick that enclose a whole cell process are more informative of the overall morphology of the interaction between cells and the collagen than are thin sections. To aid the discrimination of topography of cell processes in stereo views of micrographs, some cells were labeled with antibodies and protein A-colloidal gold conjugates. The gold particles provided clear 3D reference points for computer-aided reconstructions of membrane topography from tilt series of IVEM images. Our results confirm that cells that move through collagen lattices lack the well-spread morphology of their counterparts moving on glass. They are generally rather spindly with several long branching anterior pseudopodia. We found that the cell bodies and major pseudopodial processes were cylindrical, as one might expect of cells in a 3D environment, but at the leading edge of advancing pseudopodia there are small flat extensions similar to those seen in cells on glass. This similarity suggests that the lamellipodium is a basic type of protrusive structure used by fibroblasts during locomotion on all types of substratum. The flattened shape of lamellipodia may be part of the mechanism by which cells sense the orientation of fibrillar extracellular matrices during embryonic morphogenesis.
Computer graphic analysis of antigenic sites on the insulin molecule.
Antigenic sites on a protein have been predicted by the measurement of hydrophilicity values. We have compared this approach to the use of atomic temp factors to predict the antigenic sites on insulin. These predictions were based upon computer assisted analysis of X-ray crystallography data. The results demonstrate that the hydrophilic sites A6, B19, B23, B24, and B26 are not on the surface of the molecule and therefore are not potential antigenic determinants. Thus, hydrophilicity values alone are not sufficient to predict antigenic sites. In contrast, atomic temp factors were more predictive of antigenicity. These findings may explain why anti-insulin antibodies are less likely to develop against certain hydrophilic sites.
Digital imaging, image processing, and three-dimensional computer graphics for radiology.
The acquisition of medical images and their display, manipulation, and applications have advanced significantly in the recent past. MR imaging using ultrafast echo planar and fast gradient-echo techniques have expanded application in cardiovascular studies, as well as in the brain and spinal cord. Spiral CT has the potential to revolutionize a well-established modality, subject to several important limitations. The postprocessing of medical sectional images from MR imaging, CT, ultrasound, positron emission tomography, and single-photon emission CT has rapidly grown in importance. We have seen the emergence of renewed and expanded applications of these images, suitably processed, in directing planning and performance of therapeutic procedures on patients through stereotactic techniques, intravascular ultrasound, robot surgery, and integrated displays. This more central role of three-dimensional imaging to medical care is new and will continue to grow. Research applications have recently appeared in neuromorphometry, multimodality registration, functional neuroimaging, quantitative coronary angiography, and saturation MR techniques for myocardial tissue tagging.
Interactive three-dimensional computer graphics in molecular biology.
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Computer-graphic sectioning [proceedings].
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[Synthesis of computer graphic calculated high-anti-fixed pyrimidine nucleoside analogs with potential virostatic and antineoplastic action].
Novel C-5 substituted 6,2'-anhydrouridines 5a-e are synthesized from the hitherto unknown monosubstituted ribofuranosylbarbituric acid derivatives 4a-e. These molecules are high-anti-fixed by a 6,2'-linkage and were assumed to show antiviral and antineoplastic effects. In cell culture test systems, however, none of these biological activities could be detected up to now.
Modeling rhodopsin, a member of G-protein coupled receptors, by computer graphics. Interpretation of chemical shifts of fluorinated rhodopsins.
An attempt has been made to construct a 3-D model of rhodopsin, a member of G-protein coupled receptors. Sequence homology of rhodopsin with the latter was a factor considered in the modeling procedure. The constructed model has been used to compare currently available specific protein/substrate interaction information, the shape of the binding cavity derived from shape of binding retinal isomers and analogs and challenged to explain recently available results from a series of fluorinated rhodopsins.
A three dimensional receptor model of the dopamine D2 receptor from computer graphic analyses of D2 agonists.
Four potent D2 agonists were employed to define a primary pharmacophore for the D2 receptor. Hypothetical receptor points, representing interaction points on a receptor were built on to each molecule. These points and the nitrogen atom were averaged to give the coordinates (A) of the primary pharmacophore: R1 (0.00, 3.50, 0.00), R2 (0.00, -3.50, 0.00), R3 (5.79, 2.06, 0.00), and nitrogen (5.13, -0.63, 0.37). Eight structural classes of D2 agonists were then superimposed on to the primary pharmacophore to aid in the location of secondary binding sites. The secondary sites include two lipophilic clefts, an area of steric bulk, a region to hydrogen bond 'meta' hydroxy groups and a 'critical region' accepting methoxy and halogen substituents but not hydroxy substituents. The model has the potential to design and predict activity of novel D2 agonist compounds.
[Let's study pharmacokinetics related to anesthesiology by using computer graphics: inhalation anesthetics].
The pharmacokinetics of inhalation anesthetics has been out of public interest for 20 years. Partition coefficient or solubility of anesthetic, an important determinant of uptake and distribution of inhaled anesthetics, may be the only remains of the pharmacokinetics of inhaled anesthetics. There still, however, are a few evidences which can not be explained by partition coefficient of anesthetic. The authors applied three compartment model to the rise of the blood concentration of anesthetics, i.e., nitrous oxide, enflurane, halothane, and diethyl ether. We revealed that the change in the blood anesthetic concentration may be related to the size of compartments and their time constants. The size of compartments and their time constants may be determined by interaction of partition coefficient of anesthetic and blood distribution to the tissues which may be different with different anesthetic, and may also be different when the blood concentration of anesthetic is different.
Frog lens beta A1-crystallin: the nucleotide sequence of the cloned cDNA and computer graphics modelling of the three-dimensional structure.
Four recombinant cDNA clones coding for a 23 kDa beta-crystallin polypeptide of the frog (Rana temporaria) were identified in a collection of cloned cDNA and two of them were sequenced. The cDNA present in these clones codes for a polypeptide 198 amino-acid residues in length, which appears to be the frog beta A1-crystallin because of its high homology with the sequences of beta A1-crystallins from other species. Furthermore, the nucleotide sequence coding for the compact folded region of the protein is highly conserved. Virtually no homology was found in the 3' nontranslated regions of the mRNA. The amino-acid sequence of the Rana beta A1-crystallin was used to build a three-dimensional model based on the coordinates of the homologous bovine gamma II. An analysis of the model shows that the surface residues of the beta A1-crystallin (amphibian, mammalian and bird) are more highly conserved than the buried residues. It is suggested that this is related to the oligomeric nature of the lens beta-crystallins.
[Three-dimensional reconstruction of computed tomographic images by a computer graphics method].
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Design of intramedullary femoral stems using computer graphics.
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Design of anticancer drugs: computer graphic analysis of dihydrofolate reductase inhibitors.
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[Let's study exponential function related to anesthesiology by using computer graphics--Part II: Wash-in exponential function].
The author first explained the wash-in exponential function. Then mathematically simulated changes in the concentration of inhalation anesthetic inside a breathing circle during induction of anesthesia were shown as a physical model related to anesthesiology to explain the idea of wash-in exponential function. Effect of the flow rate and concentration of anesthetic delivered to a breathing circle on the changes in the anesthetic concentration inhaled by patients was calculated and graphed by using a computer program developed for science education. The author also stressed the importance of graphic expression in understanding various physical or biophysical phenomena related to anesthesiology.
Computer graphics: the state of the art.
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