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991.
Abstract Investigations of the structure of flowing colloidal suspensions have seen structures of predominantly hexagonal strings moving in layered arrangements in the direction of the velocity gradient. A combination of computer simulation trajectories and computer graphics show that the predominant “hexagonal string phase” is the BCC lattice sheared along its (111) slip plane and, moreover, that all the common cubic lattice types contain “hexagonal strings”. 相似文献
992.
Jason C. Sewell Hanne Duve Alan Thorpe Julianna A. Altmann 《Journal of biomolecular structure & dynamics》2013,31(2):181-199
Abstract A molecular dynamics study was undertaken to determine the conformational basis for the differing activities of the insect neuropeptide hormones calliFMRFamide 3 (SPSQDFMRF-NH2), calliFMRFamide 5 (APGQDFMRF-NH2) and their corresponding free-acid analogues (SPSQDFM- RF-OH and APGQDFMRF-OH) in two insect bioassays. A simulated annealing protocol was used to determine the range of conformers available to the linear peptides. Analysis of the conformers obtained indicated that all the peptides exhibited distinct secondary structure preferences. These, when correlated with their biological activities, enabled the formulation of putative conformation- activity relationships for the peptides. 相似文献
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Martin Hufbauer Adrian Biddle Cinzia Borgogna Marisa Gariglio John Doorbar Alan Storey Herbert Pfister Ian Mackenzie Baki Akgül 《Journal of virology》2013,87(22):12158-12165
Human papillomaviruses (HPV) of genus Betapapillomavirus (betaPV) are associated with nonmelanoma skin cancer development in epidermodysplasia verruciformis (EV) and immunosuppressed patients. Epidemiological and molecular studies suggest a carcinogenic activity of betaPV during early stages of cancer development. Since viral oncoproteins delay and perturb keratinocyte differentiation, they may have the capacity to either retain or confer a “stem cell-like” state on oncogene-expressing cells. The aim of this study was to determine (i) whether betaPV alters the expression of cell surface markers, such as CD44 and epithelial cell adhesion molecule (EpCAM), that have been associated with epithelial stemness, and (ii) whether this confers functional stem cell-like properties to human cutaneous keratinocytes. Fluorescence-activated cell sorter (FACS) analysis revealed an increase in the number of cells with high CD44 and EpCAM expression in keratinocyte cultures expressing HPV type 8 (HPV8) oncogenes E2, E6, and E7. Particularly through E7 expression, a distinct increase in clonogenicity and in the formation and size of tumor spheres was observed, accompanied by reduction of the epithelial differentiation marker Calgranulin B. These stem cell-like properties could be attributed to the pool of CD44high EpCAMhigh cells, which was increased within the E7 cultures of HPV5, -8, and -20. Enhanced EpCAM levels were present in organotypic skin cultures of primary keratinocytes expressing E7 of the oncogenic HPV types HPV5, -8, and -16 and in clinical samples from EV patients. In conclusion, our data show that betaPV may increase the number of stem cell-like cells present during early carcinogenesis and thus enable the persistence and accumulation of DNA damage necessary to generate malignant stem cells. 相似文献
995.
Alan Morris 《Ethnic and racial studies》2013,36(6):1116-1136
Xenophobia in post-apartheid South Africa has become a major issue. Much of the hostility is directed at Africans from countries north of Southern Africa who are often easily distinguishable due to their physical features, distinctive dress and inability to speak the indigenous languages. This article focuses on immigrants and asylum seekers from two countries, Nigeria and the Democratic Republic of Congo. Both groupings have experienced significant antagonism and prejudice from the local population, more especially from black South Africans. The article describes and analyses the interaction of the two groupings in question with the local populace and authorities. What is argued is that during the apartheid era the restrictions on black immigration meant that the number of black foreigners was limited. Since 1990, however, there has been a substantial increase in illegal and legal migration from Southern African countries and countries further north. This increase, in a context of growing unemployment and crime, limited infrastructural growth and fiscal resources, has intensified xenophobia against foreign Africans. The article is mainly based on in-depth interviews with Nigerian and Congolese informants living in Johannesburg's inner city. 相似文献
996.
Kazima Saira Xudong Lin Jay V. DePasse Rebecca Halpin Alan Twaddle Timothy Stockwell Brian Angus Alessandro Cozzi-Lepri Marina Delfino Vivien Dugan Dominic E. Dwyer Matthew Freiberg Andrzej Horban Marcelo Losso Ruth Lynfield Deborah N. Wentworth Edward C. Holmes Richard Davey David E. Wentworth Elodie Ghedin 《Journal of virology》2013,87(14):8064-8074
Influenza virus defective interfering (DI) particles are naturally occurring noninfectious virions typically generated during in vitro serial passages in cell culture of the virus at a high multiplicity of infection. DI particles are recognized for the role they play in inhibiting viral replication and for the impact they have on the production of infectious virions. To date, influenza virus DI particles have been reported primarily as a phenomenon of cell culture and in experimentally infected embryonated chicken eggs. They have also been isolated from a respiratory infection of chickens. Using a sequencing approach, we characterize several subgenomic viral RNAs from human nasopharyngeal specimens infected with the influenza A(H1N1)pdm09 virus. The distribution of these in vivo-derived DI-like RNAs was similar to that of in vitro DIs, with the majority of the defective RNAs generated from the PB2 (segment 1) of the polymerase complex, followed by PB1 and PA. The lengths of the in vivo-derived DI-like segments also are similar to those of known in vitro DIs, and the in vivo-derived DI-like segments share internal deletions of the same segments. The presence of identical DI-like RNAs in patients linked by direct contact is compatible with transmission between them. The functional role of DI-like RNAs in natural infections remains to be established. 相似文献
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