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71.
Background
Leucine-rich repeats are one of the more common modules found in proteins. The leucine-rich repeat consensus motif is LxxLxLxxNxLxxLxxLxxLxx- where the first 11–12 residues are highly conserved and the remainder of the repeat can vary in size Leucine-rich repeat proteins have been subdivided into seven subfamilies, none of which include members of the epidermal growth factor receptor or insulin receptor families despite the similarity between the 3D structure of the L domains of the type I insulin-like growth factor receptor and some leucine-rich repeat proteins. 相似文献72.
David M Markusic Niek P van Til Johan K Hiralall PJ Oude Ronald Elferink Jurgen Seppen 《BMC biotechnology》2009,9(1):85
Background
Lentiviral vectors are well suited for gene therapy because they can mediate long-term expression in both dividing and nondividing cells. However, lentiviral vectors seem less suitable for liver gene therapy because systemically administered lentiviral vectors are preferentially sequestered by liver macrophages. This results in a reduction of available virus and might also increase the immune response to the vector and vector products. 相似文献73.
Bayesian analysis of factorial experiments by mixture modelling 总被引:3,自引:0,他引:3
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75.
Primary antibody-forming cells and secondary B cells are generated from separate precursor cell subpopulations 总被引:22,自引:0,他引:22
Two precursor cell subpopulations have been isolated from the spleen cells of nonimmune mice. The major B cell subpopulation binds high levels of the J11D monoclonal antibody and, upon T cell-dependent antigenic stimulation, gives rise to primary antibody-forming cell clones but not secondary B cells. A minority of the 10%-14% of Ia+ precursors that bind low levels of J11D (J11Dlo) also generate antibody-forming cell clones after primary stimulation. However, over 70% of J11Dlo precursors yield no primary antibody-forming cell clones but instead give rise to secondarily responsive B cells. The existence of a distinct precursor cell subpopulation that is responsible for the generation of B cell memory is further evidenced by the distribution of variable region clonotypes among J11Dlo primary precursors, which resembles the clonotype patterns of secondary B cells, and by the accumulation of somatic mutations in their clonal progeny. 相似文献
76.
Sarfraz A Tunio Neil J Oldfield Dlawer AA Ala'Aldeen Karl G Wooldridge David PJ Turner 《BMC microbiology》2010,10(1):280
Background
Glyceraldehyde 3-phosphate dehydrogenases (GAPDHs) are cytoplasmic glycolytic enzymes, which although lacking identifiable secretion signals, have also been found localized to the surface of several bacteria (and some eukaryotic organisms); where in some cases they have been shown to contribute to the colonization and invasion of host tissues. Neisseria meningitidis is an obligate human nasopharyngeal commensal which can cause life-threatening infections including septicaemia and meningitis. N. meningitidis has two genes, gapA-1 and gapA-2, encoding GAPDH enzymes. GapA-1 has previously been shown to be up-regulated on bacterial contact with host epithelial cells and is accessible to antibodies on the surface of capsule-permeabilized meningococcal cells. The aims of this study were: 1) to determine whether GapA-1 was expressed across different strains of N. meningitidis; 2) to determine whether GapA-1 surface accessibility to antibodies was dependant on the presence of capsule; 3) to determine whether GapA-1 can influence the interaction of meningococci and host cells, particularly in the key stages of adhesion and invasion. 相似文献77.
Andreas Skouras Thomas Lang Michael Vobach Dirk Danischewski Werner Wosniok Jörn Peter Scharsack Dieter Steinhagen 《Helgoland Marine Research》2003,57(3-4):181-189
The marine flatfish dab (Limanda limanda), which lives in direct contact with contaminated sediments, is frequently used as a sentinel species in international monitoring
programmes on the biological effects of contaminants. In this study, immune responses were recorded as indicators of sublethal
chronic effects of contaminants, in addition to measurement of the induction of mono-oxygenase ethoxyresorufin O-deethylase
(EROD) in liver cells, the inhibition of acetylcholin esterase (AChE) in muscle and a quantification of grossly visible diseases
and parasites. In total, 336 dab were analysed from five sampling areas in the North Sea, including the German Bight, the
Dogger Bank, the Firth of Forth, and two locations close to oil and gas platforms (Ekofisk and Danfield). When considering
plasma lysozyme levels, pinocytosis and respiratory burst activity of head kidney leucocytes, a clear gradient could be observed
with decreased levels in individuals collected from the Firth of Forth and locations near the oil or gas platforms compared
with dab from the Dogger Bank or the German Bight. Individuals with induced EROD activity displayed reduced lysozyme and respiratory
burst activities. Lysozyme levels were also reduced in dab with lymphocystis or with nematodes. The data obtained indicate
that the assessment of innate immune parameters in a monitoring programme provides supplementary information about immunomodulatory
effects associated with the exposure of fish to contaminants. In particular, concentrations of plasma lysozyme, which can
be analysed in an easy and inexpensive assay, are considered to be an appropriate parameter for use in a battery of other
bioindicators.
Communicated by H. von Westernhagen and A. Diamant 相似文献
78.
V. Schmidt S. Zander W. Körting K. Broeg H. von Westernhagen H. Dizer P. D. Hansen A. Skouras D. Steinhagen 《Helgoland Marine Research》2003,57(3-4):262-271
In the frame of an integrated biological effect monitoring programme, the parasite community of flounder (Platichthys flesus) was investigated at different locations in the German Bight from 1995 to 2000. In order to assess the impact of environmental contamination caused by anthropogenic activities on the parasite community, selected parasitological parameters that displayed significant differences between the sampling sites were subjected to correlation analyses with site-specific contamination and individual pollution loads of their fish hosts. In addition, correlation analyses were conducted with the responses of selected genetic, biochemical, histopathological, physiological and immunological parameters of fish, used as potential biomarkers. In total, 802 flounder were analysed for these parameters. Information on the chemical background at the sampling sites was derived from sediment samples and from 120 samples of blue mussel (Mytilus edulis) tissue, collected at each of the sampling sites. Based on chemical data available from the sediment and blue mussel samples, a pollution gradient could be established between the sampling sites for individual contaminants. The relative abundance of Acanthochondria cornuta, Cucullanus heterochrous and Zoogonoides viviparus, and the community measures species richness and number of heteroxenous species decreased with increasing concentrations of individual heavy metals or hydrocarbons in sediment and blue mussel samples. Most of the parasitological parameters significantly reflected the established site-specific contamination gradient, when data were pooled over all sampling campaigns. Significant correlations were also found with the contamination level of individual flounder. The parasitological parameters included the parasite species Lepeophtheirus pectoralis and Lernaeocera branchialis, which were not correlated to site-specific contamination. Several biomarkers were significantly correlated to the abundance of parasitic copepods A. cornuta, Lernaeocera branchialis and Lepeophtheirus pectoralis and to parasite community parameters. The results showed that the abundance of several metazoan parasite species, species richness and parasite diversity were reduced in contaminated habitats, and that differences between sites were not only related to natural factors, such as salinity, but also to pollution-induced stress. Thus, it can be concluded that the parasite community of fish responds to the level of pollution at a specific site as well as to residues of xenobiotics in individual fish. These findings give indications that the parasite community of fish is a valuable parameter for the assessment of ecological consequences of chemical contamination in aquatic habitats. 相似文献
79.
For an implementation of innate immune responses of flounder (Platichthys flesus) in an integrated biological effect monitoring concept, leucocytes were isolated from peripheral blood, head kidney and spleen,
and analysed for their capacity to mount a respiratory burst response upon phorbol ester stimulation. Responding cells were
identified by reduced nitro-blue-tetrazolium salt deposits and by dihydro-rhodamine fluorescence in light microscope and flow
cytometric analysis. Responding cells were found in head kidney derived cell suspensions rather than in peripheral blood or
spleen. Parallel cytometric and microscopic analysis indicated that responding cells had a granulocyte or monocyte morphology,
were alpha-naphtyl-esterase or myeloperoxidase positive and in flow cytometry exhibited a characteristic forward and side
scatter (FSC/SSC) pattern. These cells represented 30–40% of head kidney derived cell suspensions and only 4–5 % of peripheral
blood and spleen. In order to reduce sampling effort in field studies, leucocyte cell suspensions derived from flounder head
kidney could be used in respiratory burst assays without further enrichment protocols. This paper combines, for the first
time, conventional and cytometric analysis of phagocytes derived from flounder peripheral blood and head kidney.
Communicated by H. v. Westernhagen, A. Diamant 相似文献
80.