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  • 1
    ISSN: 1432-1211
    Keywords: Key words HLA ; Patr class I molecules ; Evolution ; Polymorphism ; AIDS
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract  Human immunodefiency virus (HIV) poses a major threat to humankind. And though, like humans, chimpanzees are susceptible to HIV infection, they are considered to be resistant to the development of the acquired immune deficiency syndrome (AIDS). Little is known about major histocompatibility complex (MHC) class I diversity in chimpanzee populations and, moreover, whether qualitative aspects of Patr class I molecules may control resistance to AIDS. To address these questions, we assayed MHC class I diversity in a West African chimpanzee population and in some animals from other subspecies of chimpanzee. Application of different techniques allowed the detection of 17 full-length Patr-A, 19 Patr-B, and 10 Patr-C alleles. All Patr-A alleles cluster only into the HLA-A1/A3/A11 family, which supports the idea that chimpanzees have experienced a reduction in their repertoire of A locus alleles. The Patr-B alleles do not cluster in the same lineages as their human equivalents, due to frequent exchange of polymorphic sequence motifs. Furthermore, polymorphic motifs may have been exchanged between Patr-A and Patr-B loci, resulting in convergence. With regard to evolutionary stability, the Patr-C locus is more similar to the Patr-A locus than it is to the Patr-B locus. Despite the relatively low number of animals analyzed, humans and chimpanzees were ascertained as sharing similar degrees of diversity at the contact residues constituting the B and F pockets in the peptide-binding side of MHC class I molecules. Our results indicate that within a small sample of a West African chimpanzee population, a high degree of Patr class I diversity is encountered. This is in agreement with the fact that chimpanzees display more mitochondrial DNA variation than humans. In addition, population analyses demonstrated that particular Patr-B molecules, with the capacity to bind conserved HIV-1 epitopes, are characterized by high gene frequencies. These findings have important implications for evaluating immune responses in HIV vaccine studies and, more importantly, may help in understanding the relative resistance of chimpanzees to AIDS.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 3662-3669 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The full interaction potential between Ne(1S) and Ne+(2P) is determined by least-squares fitting of potential parameters to spectroscopic data, principally from the near-dissociation microwave spectra of the Ne2+ complex. The potential obtained in this way incorporates the potential curves for all six electronic states correlating with Ne(1S)+Ne+(2P) and the couplings between them. Coupled-channel calculations on the potential take account of breakdown of the Born–Oppenheimer approximation and provide an accurate description of the microwave rovibronic spectrum involving levels within ∼10 cm−1 of the first dissociation limit. The Ne2+ ions are both vibrationally and rotationally hot: the spectrum involves levels up to at least J=25/2 and there is evidence for transitions involving levels near the second dissociation limit. The long-range levels involved have 〈r〉 up to 12 Å, compared with an equilibrium bond length of 1.756 Å for the ground electronic state. The long-range parameters of the interaction can be extracted from the fit and are compared with recent theoretical values. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 6072-6078 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The microwave and millimeter-wave spectrum of HeH2〈sup ARRANGE="STAGGER"〉+ is reported over the frequency range 6–170 GHz. The observation of hyperfine structure in the spectra of some transitions made a clear distinction between the ortho- and para-hydrogen in the molecular ion. The hyperfine structure and double resonance Zeeman studies have enabled estimates of the quantum numbers involved in the transitions to be made. The Zeeman pattern in a 21.8 GHz doublet has been analyzed using an effective spin Hamiltonian with a case (B) basis set. This suggests an assignment of ΔN=+1, N=10←N=11. A similar analysis, in an extended hyperfine basis set, for the 15.2 GHz transition suggests an assignment of either ΔN=0, N=3, or N=4 as appropriate assumption from which to refine the potential. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Strategy & leadership 28 (2000), S. 30-36 
    ISSN: 1087-8572
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Economics
    Notes: Shareholder-value proponents claim a new, economically sound way to maximize profits, create wealth, measure performance, and reward executives. That invalid claim is dangerous. Stocks of shareholder-value firms appreciated barely 15 percent as much as another, time-tested strategic-management system. Shareholder-value strategies are easily countered. Shareholder value mis-allocates resources, revives old fallacies, and debases the reputation of economics as a useful business discipline.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    The @journal of business & industrial marketing 17 (2002), S. 151-166 
    ISSN: 0885-8624
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Economics
    Notes: Modern procurement is being shifted from paper-based, people-intensive buying systems toward electronic-based purchase procedures that rely on Internet communications and Web-enhanced buying tools. Develops a typology of e-commerce tools that have come to characterize cutting-edge industrial procurement. E-commerce aspects of purchasing are organized into communication and transaction tools that encompass both internal and external buying activities. Further, a model of the impact of e-commerce on the structure and processes of an organization's buying center is developed. The impact of the changing buying center on procurement outcomes in terms of efficiency and effectiveness is also analyzed. Finally, implications for business-to-business marketers and researchers are discussed.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The interactions of B7-1 with CD28 and CTLA-4 modulate the course of human immune responses, making B7-1 an important target for developing structure-based therapeutics. B7-1 is, however, one of the most heavily glycosylated proteins found at the leukocyte cell surface, complicating the structural analysis of this molecule. Methods for the production, crystallization and selenomethionine labelling of a soluble deglycosylated form of this molecule are described. The protein readily forms both tetragonal plate and bipyramidal crystals belonging to space groups I4122, with unit-cell parameters a = b = 56.9, c = 298.7 Å, and P4122 (or P4322), with unit-cell parameters a = b = 89.0, c = 261.9 Å, respectively. The I4122 and primitive crystal forms diffract to 2.7 and 3.5 Å, respectively. Surface plasmon resonance-based assays indicate that the ligand-binding properties of sB7-1 are unaffected by deglycosylation. Since none of the methods relied on any special structural properties of sB7-1, it is proposed that this novel combination of procedures could in principle be adapted to the systematic analysis of many other glycoproteins of structural or functional interest.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Copenhagen : International Union of Crystallography (IUCr)
    Acta crystallographica 56 (2000), S. 1473-1475 
    ISSN: 1399-0047
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The RNA-dependent RNA polymerase (P2) from bacteriophage Φ6 has been cloned and the protein overexpressed in Escherichia coli to produce an active enzyme. A fully substituted selenomethionyl version of the protein has also been produced. Crystals of both proteins have been grown; most belong to the monoclinic space group P21, with unit-cell parameters a = 105.9, b = 94.0, c = 140.9 Å, β = 101.4°, but some are trigonal (space group P31 or P32), with unit-cell parameters a = b = 110.1, c = 159.4 Å, γ = 120°. Both crystal forms occur in the same crystallization drop and are morphologically indistinguishable. Native data sets have been collected from both types of crystals to better than 3 Å resolution.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Neuroscience 25 (2002), S. 381-407 
    ISSN: 0147-006X
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology , Medicine
    Notes: Abstract Large-scale sources of neural stem cells are crucial for both basic research and novel approaches toward treating neurological disorders. Three sources that produce neural cells closely resembling their normal counterparts are now available: oncogene immortalized stem cells, neurospheres, and embryonic stem cell (ES)-derived neural cells. Cells including multiple subtypes of CNS and PNS neurons, as well as oligodendrocytes, Schwann cells, and astrocytes, are modeled by these large-scale sources. Although most cell lines were originally from rodents, their human counterparts are being discovered and characterized.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    Molecular microbiology 51 (2004), S. 0 
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Shiga toxin (Stx) genes in Stx producing Escherichia coli (STEC) are encoded in prophages of the λ family, such as H-19B. The subpopulation of STEC lysogens with induced prophages has been postulated to contribute significantly to Stx production and release. To study induced STEC, we developed a selectable in vivo expression technology, SIVET, a reporter system adapted from the RIVET system. The SIVET lysogen has a defective H-19B prophage encoding the TnpR resolvase gene downstream of the phage PR promoter and a cat gene with an inserted tet gene flanked by targets for the TnpR resolvase. Expression of resolvase results in excision of tet, restoring a functional cat gene; induced lysogens survive and are chloramphenicol resistant. Using SIVET we show that: (i) approximately 0.005% of the H-19B lysogens are spontaneously induced per generation during growth in LB. (ii) Variations in cellular physiology (e.g. RecA protein) rather than in levels of expressed repressor explain why members of a lysogen population are spontaneously induced. (iii) A greater fraction of lysogens with stx encoding prophages are induced compared to lysogens with non-Stx encoding prophages, suggesting increased sensitivity to inducing signal(s) has been selected in Stx encoding prophages. (iv) Only a small fraction of the lysogens in a culture spontaneously induce and when the lysogen carries two lambdoid prophages with different repressor/operators, 933W and H-19B, usually both prophages in the same cell are induced.
    Type of Medium: Electronic Resource
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  • 10
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Caenorhabditis elegans has previously been used as an alternative to mammalian models of infection with bacterial pathogens. We have developed a liquid-based assay to measure the effect of bacteria on the feeding ability of C. elegans. Using this assay we have shown that Pseudomonas aeruginosa strain PA14, Burkholderia pseudomallei and Yersinia pestis were able to inhibit feeding of C. elegans strain N2. An increase in sensitivity of the assay was achieved by using C. elegans mutant phm-2, in place of the wild-type strain. Using this assay,P. aeruginosa PA01 inhibited the feeding of C. elegans mutant phm-2. Such liquid-based feeding assays are ideally suited to the high-throughput screening of mutants of bacterial pathogens.
    Type of Medium: Electronic Resource
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