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At least 145 records · Page 8Linked to original sources
PubMed2001

Development of lumbosacral spina bifida: three-dimensional computer graphic study of human embryos at Carnegie stage twelve.

There is still some controversy as to whether sacral spina bifida in humans is the result of a defect of the primary or secondary neural tube. As somites are related to the development of vertebrae and the primary neural tube is related to the development of the spinal cord in embryos, it is very important to determine the number of somites in normal human embryos at the time of closure of the primary neural tube to understand the contribution of primary neural tube defects to the development of spina bifida. However, in the literature, the number of somites in stage 12 human embryos is still controversial. The aim of this study is to find the number of somites in human embryos at Carnegie stage 12. Four human embryos at Carnegie stage 12 were selected from the laboratory of the Congenital Anomaly Research Center in Japan. The neural tube and somites were reconstructed from their slices by a three-dimensional computer graphic reconstruction technique. The reconstructed embryos were examined from multidirectional magnified images. Thirty-three pairs of somites were present in all these reconstructed embryos. As the 33rd pair of somites corresponds to the fifth sacral segment, the presence of 33 pairs of somites at Carnegie stage 12 suggests that spina bifida develops from defects of the primary neural tube.

Computer Graphics↗
PubMed1992

[Three-dimensional reconstruction of cytoskeletons in rat salivary glands using confocal fluorescence microscopy and volume-rendering computer graphics].

A new reconstruction technique for the demonstration of three-dimensional architectural details from biological fluorescent specimens was used to determine the precise spacial organization of F-actin in rat sublingual glands. F-actin was stained with NBD-phallacidin in thick (20-30 microns) frozen sections and observed with a confocal laser scanning microscope to obtain thin (-1 micron) optically sectioned images. A series of optical sections taken successively at different focal levels in steps of 1 micron was then reconstructed with volume-rendering computer graphics. The rendered images viewed from several angles (e.g. top, bottom, sides) clearly revealed the presence of F-actin fluorescence along the hexagonal framework of the junctional complex within the acini and in the cytoplasm of star-shaped myoepithelial cells encircling the acini. The detailed structures and the topographical relations between the junctional complex and myoepithelial cells were more impressively observed when the rendered images were displayed by motion picture. These images are free from any artifacts caused by the mechanical sectioning and revealed well the delicate and complicated profiles of cellular structures that previously have been almost impossible to demonstrate by conventional reconstruction techniques. We expect that the combination of confocal microscopy and volume rendering will permit the dynamic observation of previously unseen phenomena in three dimensions, such as the behavior of biologically active molecules in living cells.

Animals↗
PubMed1978

Development of a method of evaluating cardiac performance using interactive computer graphics.

The authors discuss an objective method of analyzing local wall motion to detect and measure the pattern of contraction of the left ventricle using computer graphics. The method's advantages include: (a) the use of modular hardward and software, which can be extended and upgraded; (b) a minimal expenditure of time and money; (c) uniformly calculated results; and (d) a graphic and legible report.

Computers↗
PubMed1989

[The mechanism of blood outflow from the cavernous tissue of human penis by computer graphics].

There are two theories concerning the mechanisms of human penile erection and its maintenance. One theory goes that the artery responsible for blood inflow into the cavernous space relaxes, while the vein responsible for blood outflow actively contracts. The other theory asserts that no active closing mechanism in present in the penile venous system, but rather the erection is totally controlled by the amount of blood inflow. In order to corroborate the vascular construction of the penis, we prepared serial sections of the penis specimens obtained at autopsy and observed these sections by light microscopy, and we investigated the construction of veins which let blood flow out from the corpus cavernosum penis by computer graphics. As a result, we were unable to find any valves in the blood outflow system. Moreover, efferent vessels were seen to let blood flow from the cavernous spaces, after running immediately below the tunica albuginea for a small distance, to the tunica albuginea, running obliquely through inner veins toward the outside of the tunica albuginea in the direction of the long axis of the penis; then these veins are continuous to the veins on the tunica albuginea. From the above-mentioned structures we can infer the following mechanism of penile erection.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1983

A computer graphics study of sequence-directed bending in DNA.

We present theoretical results to account for the unusual physical properties of a 423 bp DNA restriction fragment isolated from the kinetoplast of the trypanosomatid Leishmania tarentolae. This fragment has an anomalously low electrophoretic mobility in polyacrylamide gels and a rotational relaxation time smaller than that of normally-behaved control fragments of the same molecular weight. Our earlier work (Proc. Natl. Acad. Sci. USA 79, 7664, 1982) has attributed these anomalies to the highly periodic distribution of the dinucleotide ApA in the DNA sequence. As originally proposed by Trifonov and Sussman (Proc. Natl. Acad. Sci. USA 77, 3816, 1980) local features of the DNA structure such as a small bend at ApA, if repeated with the periodicity of the helix, will cause systematic bending of the molecule. Computer graphics representations of DNA chain trajectories are presented for different structural models. It is shown that the structural model of Calladine (J. Mol. Biol. 161, 343, 1982) which is based on crystallographic data, is unsuccessful in predicting the systematic bending of DNA in solution.

Animals↗
PubMed1984

Structure-activity relationships of sulfonamide drugs and human carbonic anhydrase C: modeling of inhibitor molecules into the receptor site of the enzyme with an interactive computer graphics display.

We have analyzed the molecular interaction of 28 sulfonamide inhibitors with human carbonic anhydrase C (HCAC) using an interactive computer graphic display. Small aromatic sulfonamides gain most of their inhibitory power towards HCAC from the interaction of hydrogen bond acceptors at the para or meta positions with hydrophilic residues of the enzyme. Additional coordinated water molecules stabilize the complexes of heterocyclic sulfonamides (i.e., thiophenes, 1,3-thiazoles, and 1,3,4-thiadiazoles) with HCAC. We propose two different modes of binding of the heterocyclic ring with respect to the active site cleft: the heterocyclic sulfur atom of a 3,4-unsubstituted thiophene approaches the oxygen atom of a coordinated water molecule (sulfur "out"), whereas in 3,4-unsubstituted 1,3,4-thiadiazoles, the sulfur is in contact with a hydrophobic part of the receptor site (sulfur "in"). This proposal is consistent with crystallographic evidence. Sulfonamides with two aromatic or heterocyclic rings also interact with a hydrophobic pocket of the enzyme located greater than 10 A away from the active site metal Zn2+. We also discuss the possibility that the relative inactivity of thiazide diuretics is due to the steric interaction of the ortho chlorine atom with the enzyme receptor cavity.

Binding Sites↗
PubMed1995

Spatial performance with perspective displays as a function of computer graphics eyepoint elevation and geometric field of view.

The purpose of this study was to investigate the effect of varying the elevation of the computer graphics eyepoint and the geometric field of view on judgements of spatial information using a stereoscopic perspective display. Twelve subjects judged the elevation and azimuth angle separating two computer-generated objects viewed using an eyepoint elevation that ranged between -15 degrees and 45 degrees and a geometric field of view that ranged between 40 degrees and 80 degrees. The results of the study indicated that judgements of elevation were affected by the compression of the vertical axis resulting from the raised eyepoint elevation. Furthermore, azimuth judgements were influenced by both the eyepoint elevation and the geometric field of view. Implications of the results for the design of displays and for spatial performance using stereoscopic displays are discussed.

Journal Article↗
PubMed2000

[Possibilities of computer graphics simulation in orthopedic surgery].

BACKGROUND: In addition to standard X-rays, photographic documentation, cephalometric and model analysis, a computer-aided, three-dimensional (3D) simulation system has been developed in close cooperation with the Institute of Communications of the Friedrich-Alexander-Universität Erlangen-Nürnberg. With this simulation system a photorealistic prediction of the expected soft tissue changes can be made. Prerequisites are a 3D reconstruction of the facial skeleton and a 3D laser scan of the face. After data reduction, the two data sets can be matched. Cutting planes enable the transposition of bony segments. The laser scan of the facial surface is combined with the underlying bone via a five-layered soft tissue model to convert bone movements on the soft tissue cover realistically. CONCLUSION: Further research is necessary to replace the virtual subcutaneous soft tissue model by correct, topographic tissue anatomy.

Cephalometry↗
PubMed2000

Structure of glutamate decarboxylase and related PLP-enzymes: computer-graphical studies.

Amino acid sequences of E. coli glutamate decarboxylase (GADa) and those of 36 GAD of different origin were compared by pairwise alignment using computer program CLUSTAL. GADalpha and plant enzymes showed 59.8-67.8% subunit homology, GADalpha and other bacterial GAD--49.8-77.6%, whereas GADalpha and animal enzymes--13.9-58.8%. Two PLP domains exhibited higher homology comparing to that of the whole subunit in the case of GAD67, plant (68.4-73.9%), and bacterial (46.7-83.2%) enzymes. The alignment of PLP-domains of 37 GAD, three group II decarboxylases, and two pyridoxal enzymes with known 3D structures (bacterial ORD and mAAT from chicken heart) allowed us to reveal conserved residues of the active sites. Their functional role is discussed. Modelling of the PLP-binding sites in active centers for GADalpha and human brain GAD67 was done using the Swiss-PdbViewer homology modelling program. Although the homology between GADalpha and GAD67 is rather low, structural similarity of their active sites allows us to consider here a functional convergence. Thus, glutamate decarboxylation by GADalpha may be helpful for understanding general mechanism of this reaction.

Amino Acid Sequence↗
PubMed1986

Structural variation in mammalian gamma-crystallins based on computer graphics analyses of human, rat and calf sequences. 1. Core packing and surface properties.

A comparison of mammalian gamma-crystallins has been made by computer-graphics model building of several gamma-crystallin sequences based on the atomic co-ordinates of the X-ray determined structure of calf gamma-II crystallin. The complete family of rat gamma-crystallins is compared together with the orthologous protein, gamma 1-2 crystallin, from rat, human and calf lens, and the orthologous protein, gamma 2-1 crystallin, from rat and human lens. In human gamma-crystallins, a major structural difference, the replacement of an arginine by a cysteine, occurs in one of the four-fold repeated folded hairpins, which may affect stability. Sequence variations involving buried residues were observed, leading to small differences in core packing of the different sequences which may be related to their regional location in the lens. Model-building studies also indicate that the surfaces of the different gamma-crystallins vary in number of exposed hydrophobic residues and ion pairs. These differences would affect protein-water interactions and therefore contribute to refractive index. A major variable region of the gamma-crystallin structures involves polar residues surrounding the inter-domain contact and the length of the polypeptide connecting the two domains. An attempt is made to correlate bovine gamma-crystallins which are known to be responsible for cold cataract with the corresponding sequences from rat lens.

Amino Acid Sequence↗
PubMed2001

Discrimination of computer-graphic stimuli by mice: a method for the behavioral characterization of transgenic and gene-knockout models.

An automated method is described for the behavioral testing of mice in an apparatus that allows computer-graphic stimulus material to be presented. Mice responded to these stimuli by making a nose-poke toward a computer monitor that was equipped with a touchscreen attachment for detecting responses. It was found that C57BL/6 mice were able to solve single-pair visual discriminations as well as 3-pair concurrent visual discriminations. The finding that mice are capable of complex visual discriminations introduces the possibility of testing mice on nonspatial tasks that are similar to those used with rats, monkeys, and humans. Furthermore, the method seems particularly well suited to the comprehensive behavioral assessment of transgenic and gene-knockout models.

Animals↗