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961.
The bioprocess development cycle is a complex task that requires a complete understanding of the engineering of the process (e.g., mass transfer, mixing, CO(2) removal, process monitoring, and control) and its affect on cell biology and product quality. Despite their widespread use in bioprocess development, spinner flasks generally lack engineering characterization of critical physical parameters such as k(L)a, P/V, or mixing time. In this study, mass transfer characterization of a 250-mL spinner flask using optical patch-based sensors is presented. The results quantitatively show the effect of the impeller type, liquid filling volume, and agitation speed on the volumetric mass transfer coefficient (k(L)a) in a 250-mL spinner flask, and how they can be manipulated to match mass transfer capability at large culture devices. Thus, process understanding in spinner flasks can be improved, and these devices can be seamlessly integrated in a rational scale-up strategy from cell thawing to bench-scale bioreactors (and beyond) in biomanufacturing. 相似文献
962.
Inhibition of human immunodeficiency virus replication by a dual CCR5/CXCR4 antagonist 总被引:4,自引:0,他引:4 下载免费PDF全文
Princen K Hatse S Vermeire K Aquaro S De Clercq E Gerlach LO Rosenkilde M Schwartz TW Skerlj R Bridger G Schols D 《Journal of virology》2004,78(23):12996-13006
Here we report that the N-pyridinylmethyl cyclam analog AMD3451 has antiviral activity against a wide variety of R5, R5/X4, and X4 strains of human immunodeficiency virus type 1 (HIV-1) and HIV-2 (50% inhibitory concentration [IC(50)] ranging from 1.2 to 26.5 microM) in various T-cell lines, CCR5- or CXCR4-transfected cells, peripheral blood mononuclear cells (PBMCs), and monocytes/macrophages. AMD3451 also inhibited R5, R5/X4, and X4 HIV-1 primary clinical isolates in PBMCs (IC(50), 1.8 to 7.3 microM). A PCR-based viral entry assay revealed that AMD3451 blocks R5 and X4 HIV-1 infection at the virus entry stage. AMD3451 dose-dependently inhibited the intracellular Ca(2+) signaling induced by the CXCR4 ligand CXCL12 in T-lymphocytic cells and in CXCR4-transfected cells, as well as the Ca(2+) flux induced by the CCR5 ligands CCL5, CCL3, and CCL4 in CCR5-transfected cells. The compound did not interfere with chemokine-induced Ca(2+) signaling through CCR1, CCR2, CCR3, CCR4, CCR6, CCR9, or CXCR3 and did not induce intracellular Ca(2+) signaling by itself at concentrations up to 400 microM. In freshly isolated monocytes, AMD3451 inhibited the Ca(2+) flux induced by CXCL12 and CCL4 but not that induced by CCL2, CCL3, CCL5, and CCL7. The CXCL12- and CCL3-induced chemotaxis was also dose-dependently inhibited by AMD3451. Furthermore, AMD3451 inhibited CXCL12- and CCL3L1-induced endocytosis in CXCR4- and CCR5-transfected cells. AMD3451, in contrast to the specific CXCR4 antagonist AMD3100, did not inhibit but enhanced the binding of several anti-CXCR4 monoclonal antibodies (such as clone 12G5) at the cell surface, pointing to a different interaction with CXCR4. AMD3451 is the first low-molecular-weight anti-HIV agent with selective HIV coreceptor, CCR5 and CXCR4, interaction. 相似文献
963.
Differential expression of annexins I, II and IV in human tissues: an immunohistochemical study 总被引:6,自引:0,他引:6
Rita Dreier Kurt Werner Schmid Volker Gerke K. Riehemann 《Histochemistry and cell biology》1998,110(2):137-148
Annexins constitute a family of Ca2+- and phospholipid-binding proteins. Although their functions are still not clearly defined, several members of the annexin
family have been implicated in membrane-related events along exocytotic and endocytotic pathways. To elucidate a possible
correlation of those functional proposals with the tissue distribution of annexins, we analysed immunohistochemically the
expression of annexins I, II and IV in a broad variety of human tissues. Annexins I and II were chosen for this study since
their functionally relevant N-terminal domains are structurally closely related, whilst annexin IV is structurally less related
to the former two proteins. The study revealed distinct expression patterns of annexins I, II and IV throughout the body.
Annexin I was found in leucocytes of peripheral blood, tissue macrophages and T-lymphocytes and in certain epithelial cells
(respiratory and urinary system, superficial cells of non-keratinised squamous epithelium), annexin II in endothelial cells,
myoepithelial cells and certain epithelial cells (mainly respiratory and urinary system), whereas annexin IV was almost exclusively
found in epithelial cells. Epithelia of the upper respiratory system, Bowman’s capsule, urothelial cells, mesothelial cells,
peripheral nerves, the choroid plexus, ependymal cells and pia mater and arachnoid of meninges generally strongly expressed
all three annexins investigated. The characteristic expression in different tissues and the intracellular distribution indicates
that the three annexins investigated are involved in aspects of differentiation and/or physiological functions specific to
these tissues.
Accepted: 15 January 1998 相似文献
964.
Species Diversity of and Toxin Production by Gibberella fujikuroi Species Complex Strains Isolated from Native Prairie Grasses in Kansas 下载免费PDF全文
John F. Leslie Kurt A. Zeller Antonio Logrieco Giuseppina Mulè Antonio Moretti Alberto Ritieni 《Applied microbiology》2004,70(4):2254-2262
Fusarium species from agricultural crops have been well studied with respect to toxin production and genetic diversity, while similar studies of communities from nonagricultural plants are much more limited. We examined 72 Fusarium isolates from a native North American tallgrass prairie and found that Gibberella intermedia (Fusarium proliferatum), Gibberella moniliformis (Fusarium verticillioides), and Gibberella konza (Fusarium konzum) dominated. Gibberella thapsina (Fusarium thapsinum) and Gibberella subglutinans (Fusarium subglutinans) also were recovered, as were seven isolates that could not be assigned to any previously described species on the basis of either morphological or molecular characters. In general, isolates from the prairie grasses produced the same toxins in quantities similar to those produced by isolates of the same species recovered from agricultural hosts. The G. konza isolates produce little or no fumonisins (up to 120 μg/g by one strain), and variable but generally low to moderate amounts of beauvericin (4 to 320 μg/g) and fusaproliferin (50 to 540 μg/g). Toxicity to Artemia salina larvae within most species was correlated with the concentration of either beauvericin or fusaproliferin produced. Organic isolates from some cultures of G. moniliformis were highly toxic towards A. salina even though they produced little, if any, beauvericin or fusaproliferin. Thus, additional potentially toxigenic compounds may be synthesized by G. moniliformis strains isolated from prairie grasses. The Fusarium community from these grasses appears to contain some species not found in surrounding agricultural communities, including some that probably are undescribed, and could be capable of serving as a reservoir for strains of potential agricultural importance. 相似文献
965.
Murat Budakoglu Halil Kurt Muhittin Karaman Mert Kumru Mustafa Kumral 《Geomicrobiology journal》2014,31(6):454-460
Archaeal diversity in Lake Ac?göl, a closed-basin, alkaline, hypersaline lake located at the northern edge of western Tourides in southwest Anatolia, was investigated using culture-independent methods. Microbial mat samples were collected from six different points. Archaeal 16S rRNA gene libraries were generated using domain specific oligonucleotide primers, and 16S rRNA gene sequences of clone libraries were analyzed phylogenetically. Denaturing gradient gel electrophoresis of 16S rRNA genes showed a variance in diversity with spatial differences. Archaeal diversity of Ac?göl is dominated by the members of family Halobacteriaceae which requires both high salt concentration and high pH for growth. Sequence analysis of archaeal 16s rRNA genes indicates the presence of the phylotypes affiliated with the genera Halorubrum, Halosimplex, Halorhabdus, Haloterrigena and Natronococcus in the analyzed samples. 相似文献
966.
Hohensinner PJ Kaun C Rychli K Ben-Tal Cohen E Kastl SP Demyanets S Pfaffenberger S Speidl WS Rega G Ullrich R Maurer G Huber K Wojta J 《FEBS letters》2006,580(14):3532-3538
The chemokine MCP-1 is thought to play a key role - among many other pathophysiological processes - in myocardial infarction. MCP-1 is not only a key attractant for monocytes and macrophages and as such responsible for inflammation but might also be directly involved in the modulation of repair processes in the heart. We show that cultured human cardiac cells express MCP-1 and that its expression is upregulated by inflammatory cytokines and downregulated by hypoxia. We hypothesize that inflammation but not hypoxia is the main trigger for monocyte recruitment in the human heart. 相似文献
967.
DNA-wrapped nanotubes of both multiwalled and single-walled carbon nanotubes were obtained by a solid-state mechanochemical reaction. Scanning electron microscopic images show that the nanotubes were cut into shorter lengths and were fully covered with DNA, which was further confirmed by fluorescence microscopy. This resulted in a high aqueous solubility of the products with a stability of >6 months. The results show that nanotubes were cut also with uniform distribution where >90% of the multiwalled products were 500 nm to 3 microm and 80% of the single-walled products were 250 nm to 1 microm in length, respectively. UV-vis spectra and gel electrophorosis show that the DNA in the product is intact. This facile technique for obtaining supramolecularly masked, water-soluble carbon nanotubes by a solid-state reaction has a great potential for both biological and nonbiological applications of nanotubes. 相似文献
968.
Flemming Skov 《植被学杂志》1997,8(4):573-578
Abstract. Patterns of species richness in a managed forest were related to ecological factors at two spatial scales. Local variables within a plot (5 m × 5 m) included 13 soil classes and nine stand classes. Neighbourhood variables were defined within a 25 m radius from the focal plot and were measured using a Neighbourhood Diversity Index (NDI - total diversity of different stand classes) and nine Neighbourhood Scores (NS - relative dominance of a given stand class). 224 species were registered in the survey of which 138 were true forest species. Local parameters (stand and soil class) were weak predictors of total and forest species richness. High total and forest species richness were significantly related to high values of NDI (i.e. heterogeneous neighbourhoods). Regression trees showed that total species richness was best predicted by the amount of roadside habitat in the neighbourhood and NDI. Forest species richness was positively related to NDI and negatively related to the amount of coniferous stands in the neighbourhood. 相似文献
969.
Scar assessment tools: implications for current research 总被引:12,自引:0,他引:12
van Zuijlen PP Angeles AP Kreis RW Bos KE Middelkoop E 《Plastic and reconstructive surgery》2002,109(3):1108-1122
Scarring is considered a major medical problem that leads to cosmetic and functional sequelae. Scar tissue is clinically distinguished from normal skin by an aberrant color, rough surface texture, increased thickness (hypertrophy), occurrence of contraction, and firmness. Marked histologic differences are the change in dermal architecture and the presence of cells such as the myofibroblast. Many assessment tools are available for analysis of pathologic conditions of the skin; however, there is no general agreement as to the most appropriate tools for evaluation of scar tissue. This review critically discusses currently available objective measurement tools, subjective assessment tools, and potential devices that may be available in the future for scar assessment. 相似文献
970.
Autoregulation of the dnaA gene of Escherichia coli K12 总被引:31,自引:0,他引:31
Tove Atlung Erik S. Clausen Flemming G. Hansen 《Molecular & general genetics : MGG》1985,200(3):442-450