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  • 1995-1999  (5)
  • 1999  (5)
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  • 1995-1999  (5)
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  • 1
    Electronic Resource
    Electronic Resource
    Fine structure of bovine morulae and blastocysts in vivo and in vitro (1999)
    Springer
    Anatomy and embryology 199 (1999), S. 519-527 
    Details
    ISSN: 1432-0568
    Keywords: Key words Morphology ; Embryo culture ; Lipid droplet ; Development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The ultrastructure of bovine morulae and blastocysts developed from in vitro-matured and -fertilized oocytes in a serum-supplemented medium was compared with that of morulae and blastocysts collected non-surgically from superovulated cows. In the in vivo-derived morulae, two characteristic cells types could be identified by the electron-density of their cytoplasm and by their ultrastructural features. One type appeared light in color with low electron-dense cytoplasm. These cells were located in the peripheral layer of the cluster of blastomeres, possessed numerous cellular organelles such as mitochondria and Golgi apparatus and had microvilli projecting into the perivitelline space. The other cell type was distinguished by cytoplasm that stained more densely than that of the lighter-appearing cells. The darker-appearing cells generally possessed fewer organelles than the lighter cells, but many lysosome-like structures were present in the cytoplasm. The in vitro-developed morulae also contained two types of cells similar to those observed in the in vivo morulae. However, most of the in vitro-developed cells possessed numerous lipid droplets and contained fewer lysosome-like structures than the cells of the in vivo-derived morulae. The blastocysts, both in vivo and in vitro, showed a clear differentiation of trophoblast cells and inner cell mass (ICM)-cells. In the in vivo-derived blastocyst, the apical membrane of trophoblast cells was covered with large, numerous microvilli and well-developed junctional complexes were observed. Lipid droplets were present in the cytoplasm of trophoblast and ICM-cells but were not abundant. In vitro-developed blastocysts showed less well-developed junctional complexes between trophoblast cells, less well-developed apical microvilli on the trophoblast cells, and contained large numbers of lipid droplets. This accumulation of lipid droplets was higher in the trophoblast cells than in the ICM-cells. The zonae pellucidae of in vitro-developed embryos were thinner than that of the in vivo-derived embryos. This study demonstrates conspicuous differences in the ultrastructural features between the in vivo-derived and in vitro-developed embryos, suggesting that the ultrastructure may reflect the various physiological anomalies observed in previous studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004290050249
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Does chewing performance depend upon a specific masticatory pattern? (1999)
    Oxford, UK : Blackwell Science Ltd
    Journal of oral rehabilitation 26 (1999), S. 0 
    Details
    ISSN: 1365-2842
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The purpose of this article is to review the literature concerning the ideal chewing pattern for best chewing performance. We conclude that at this time there is not one ideal chewing pattern which can be used clinically or in research to assess the health of the mastication apparatus nor to predict chewing performance. It is clear that human masticatory behaviour is one of the most complex human behaviours. Chewing is under the control of the central pattern generator located in the brain stem but is influenced by dental and temporomandibular joint morphology. The most important portion of the chewing cycle is the area entering and leaving the intercuspal position where gliding contacts occur. Maximal chewing capability will likely occur when the chewing pattern follows the dental anatomy unique to the individual. The chewing cycle appears to increase the lateral component of its movement when increased chewing efficiency is required. These situations include increased hardness or the size of bolus, the position of the bolus and the results of the proceeding chewing stroke. The chewing pattern for any one cycle is influenced by a number of factors, thus it is not surprising that the question of the ideal chewing pattern remains unresolved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2842.1999.00446.x
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Controlled spontaneous emissions from current-driven semiconductor microcavity triodes (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 74 (1999), S. 1278-1280 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We demonstrate the alteration of spontaneous emissions in semiconductor microcavity triodes, in which the carriers are injected by current into a single quantum well (QW) active region and the emission wavelength was varied by the voltage applied to the QW through the quantum confined Stark effect. The clear changes in the emission spectra and radiation patterns with the change of the voltage manifest that the spontaneous emission is well modified by the microcavity under the control of the applied voltage. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.123523
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    An experimental study on a wake behind a torus using the UVP monitor (1999)
    Springer
    Experiments in fluids 26 (1999), S. 197-207 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  The flow around a torus has a complicated three-dimensional structure. Measuring the spatiotemporal field of velocity by means of conventional methods such as hot-wire anemometers and other one-point measuring instruments is thus difficult. Research is made on the spatiotemporal structure of the wake behind the torus by using a flow-visualizing technique and an ultrasonic velocity profile (UVP) monitor, in which two kinds of tori with different diameter ratios or solidity are set in a uniform flow with zero inclination and oblique postures. For the torus with zero inclination, there are two modes of flow structure according to the diameter ratio; at lower ratio, a disk mode is dominant, and at higher ratio, a ring wake mode appears. For the torus set with an oblique posture, the structure of the wake changes with respect to the oblique angle in a complicated fashion. The power spectra of the fluctuating velocities reveal an aspect of the character of this structural change. The Strouhal numbers estimated from the power spectra suggest that the flow patterns can be classified into four categories with respect to the oblique angle.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003480050280
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Two novel mutations of SURF1 in Leigh syndrome with cytochrome c oxidase deficiency (1999)
    Springer
    Human genetics 〈Berlin〉 105 (1999), S. 560-563 
    Details
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract. Cytochrome c oxidase (COX) deficiency is the most common cause of Leigh syndrome (LS). COX consists of ten nuclear-encoded and three mtDNA-encoded structural subunits. Although the nucleotide sequences of all 13 genes are known, no mutation was found in nuclear-encoded subunit genes of COX-deficiency patients. Zhu et al. (1998) and Tiranti et al. (1998) found nine mutations in the surfeit 1 (SURF1) gene in LS families with COX deficiency. The mouse surfeit gene cluster consists of six closely spaced housekeeping genes unrelated by sequence homology. Except for the Surf3 gene, the function is still not known. The juxtaposition of at least five of the surfeit genes is conserved between birds and mammals. We identified two novel mutations of SURF1 in a Japanese LS patient with COX deficiency using direct sequencing analysis. Firstly, a 2-bp deletion at nucleotide position 790 (790delAG) in exon 8 was found, which shifts the reading frame such that the mutant protein has a completely different amino acid sequence from codon 264 to the premature stop codon at 290. Secondly, we found a T-to-G transversion at nucleotide 820, resulting in the substitution of tyrosine by aspartic acid at codon 274 (Y274D). We also studied the parents' genes, and found that the Y274D mutation was in his father and the 790delAG mutation was in his mother heterozygously. Therefore, we concluded that the patient was a compound heterozygote with these mutations. These are the first pathogenetic SURF1 mutations identified in a Japanese family.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004399900191
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    Paper (German National Licenses)
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