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31.
Photosystem I (PSI) complex of Anabaena variabilis ATCC 29413 consists of at least 11 subunits, 9 of which are resolved by high resolution gel electrophoresis. N-terminal amino acid sequences of the four subunits with molecular masses of 6.8, 5.2, 4.8 and 3.5 kDa were determined. Based on the sequence homology, the 3.5 kDa subunit was revealed to correspond to PSI-I (the gene product of psaI), which had so far been detected only in higher plant PSI complexes. The 6.8 kDa protein and 4.8 kDa protein were identified as gene products of psaK and psaJ, respectively. The 5.2 kDa protein was homologous to a 4.8 kDa subunit of PSI of the thermophilic cyanobacterium Synechococcus vulcanus, suggesting that this protein is a component of PSI in cyanobacteria. 相似文献
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Julie K. Nyhus Chris C. Wolford Chad R. Friece Bud M. Nelson James W. Sampsel Emilio Barbera-Guillem 《Cancer immunology, immunotherapy : CII》2001,50(7):361-372
Tumors secreting glycoproteins that act as tumor-associated antigens have been described as highly invasive and metastatic. In this study, the consequences of the humoral immune response (HIR) against these antigens were investigated. Using an in vitro model of tumor cell invasion, results indicated that the invasiveness of tumor cells secreting antigenic secreted/shed tumor glycoproteins (STGP) increases in the presence of specific anti-STGP IgG, polymorphonuclear cells and monocytes. This in vitro model showed that the coincidental presence in the matrix of both STGP and specific anti-STGP IgG increases the local release of IL-1beta, IL-6 and vascular endothelial growth factor (VEGF) by stromal cells, but not by tumor cells. Using an in vivo model, the experiments show that immune-competent mice develop an anti-tumor HIR with anti-STGP IgG production. In this model, tumor growth was increased in parallel with the serum concentration of specific anti-STGP IgG. In athymic nude (nu/nu)-beige mice the same trend was observed, suggesting a T-cell-independent tumor-promoting effect induced by anti-STGP IgG. Tumor histology showed intense infiltration of IgG-positive plasma cells and lymphocytes. A severe combined immunodeficient-beige mouse-based in vivo model of tumors, experimentally infiltrated with monoclonal IgG plasmocytoma cells, showed that only specific anti-STGP-IgG-secreting cells could exacerbate tumor invasion, angiogenesis and metastasis. These results suggest that tumors shedding/secreting antigenic STGP can induce a host IgG immune response that can promote invasion and metastasis by inducing tumor infiltrating stromal cells to release proinflammatory cytokines and VEGF. 相似文献
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Inès J Goossens-Beumer Jan Oosting Wim E Corver Marjolein JFW Janssen Bart Janssen Wilbert van Workum Eliane CM Zeestraten Cornelis JH van de Velde Hans Morreau Peter JK Kuppen Tom van Wezel 《BMC genomics》2015,16(1)
Background
In rectal cancer, total mesorectal excision surgery combined with preoperative (chemo)radiotherapy reduces local recurrence rates but does not improve overall patient survival, a result that may be due to the harmful side effects and/or co-morbidity of preoperative treatment. New biomarkers are needed to facilitate identification of rectal cancer patients at high risk for local recurrent disease. This would allow for preoperative (chemo)radiotherapy to be restricted to high-risk patients, thereby reducing overtreatment and allowing personalized treatment protocols. We analyzed genome-wide DNA copy number (CN) and allelic alterations in 112 tumors from preoperatively untreated rectal cancer patients. Sixty-six patients with local and/or distant recurrent disease were compared to matched controls without recurrence. Results were validated in a second cohort of tumors from 95 matched rectal cancer patients. Additionally, we performed a meta-analysis that included 42 studies reporting on CN alterations in colorectal cancer and compared results to our own data.Results
The genomic profiles in our study were comparable to other rectal cancer studies. Results of the meta-analysis supported the hypothesis that colon cancer and rectal cancer may be distinct disease entities. In our discovery patient study cohort, allelic retention of chromosome 7 was significantly associated with local recurrent disease. Data from the validation cohort were supportive, albeit not statistically significant, of this finding.Conclusions
We showed that retention of heterozygosity on chromosome 7 may be associated with local recurrence in rectal cancer. Further research is warranted to elucidate the mechanisms and effect of retention of chromosome 7 on the development of local recurrent disease in rectal cancer.Electronic supplementary material
The online version of this article (doi:10.1186/s12864-015-1550-0) contains supplementary material, which is available to authorized users. 相似文献36.
Studies of the hyaluronan (HA) tetrasaccharides are important for
understanding hydrogen-bonding in the HA polymer, as they are probably the
smallest oligomers in which characteristics of the constituent
monosaccharides and the polymer are simultaneously exhibited. Here we
present extensive molecular dynamics simulations of the two
tetrasaccharides of HA in dilute aqueous solution. These simulations have
confirmed the existence of intramolecular hydrogen-bonds between the
neighboring sugar residues of HA in solution, as proposed by Scott (1989).
However, our simulations predict that these intramolecular hydrogen-bonds
are not static as previously proposed, but are in constant dynamic exchange
on the sub-nanosecond time-scale. This process results in discrete internal
motion of the HA tetrasaccharides where they rapidly move between low
energy conformations. Specific interactions between water and
intramolecular hydrogen-bonds involving the hydroxymethyl group were found
to result in differing conformations and dynamics for the two alternative
tetrasaccharides of HA. This new observation suggests that this residue may
play a key role in the entropy and stability of HA in solution, allowing it
to stay soluble up to high concentration. The vicinal coupling constants3 J
NHCH of the acetamido groups have been calculated from our aqueous
simulations of HA. We found that high values of 3J NHCH approximately 8 Hz,
as experimentally measured for HA, are consistent with mixtures of both
trans and cis conformations, and thus3 J NHCH cannot be used to imply a
purely trans conformation of the acetamido. The rapid exchange of
intramolecular hydrogen-bonds indicates that although the structure is at
any moment stabilized by these hydrogen-bonds, no one hydrogen-bond exists
for an extended period of time. This could explain why NMR often fails to
provide evidence for intramolecular hydrogen-bonds in HA and other aqueous
carbohydrate structures.
相似文献
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O Holian R Kumar L M Nyhus 《Biochemical and biophysical research communications》1989,160(3):1110-1116
Purified rat pancreas protein kinase C (PKC) is activated by unsaturated free fatty acids (oleic and arachidonic). The ethyl esters of these fatty acids are ineffective as enzyme activators. However, when the ethyl esters are added in combination with a free fatty acid, there is significant enhancement of enzyme activation. Nearly optimal PKC activation was obtained when non-activating ethyl oleate or ethyl arachidonate was added to sub-optimally activating concentrations of oleic or arachidonic acids. In addition to the ethyl esters, 1-monooleylglycerol also had a potentiating effect on PKC activation by oleic acid. However, the degree of activation observed in the presence of a free fatty acid and an acyl ester of the fatty acid quantitatively never surpassed that produced by sn-1,2-dioleylglycerol. Our findings indicate that significant PKC activation can be achieved by presenting the enzyme with an environment which we believe approximates the structural characteristics of the endogenous activator, sn-1,2-diacylglycerol. 相似文献
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Randomly obtained, constitutive plasma membrane ferric reductase/ferrous uptake mutants of Cryptococcus neoformans were mapped to four distinct loci by meiotic analysis. One of those loci, FRR1 , was previously found homologous to MRS3 and MRS4 of Saccharomyces cerevisiae , which determine proteins involved in mitochondrial transport of iron. We were able to complement, clone, sequence and thereby identify two of the three remaining constitutive uptake loci. FRR3 was found to be homologous to ISU1 and ISU2 of S. cerevisiae, which form mitochondrial iron–sulfur complexes; FRR4 was found to be homologous to YFH1, the yeast frataxin homologue, which also participates in iron–sulfur cluster biogenesis. Because of the constitutive iron uptake seen in these mutants, mitochondria appear to have a central role in the cellular iron economy; moreover, as judged by our mutational statistics, the genetic machinery for mitochondrial iron accumulation may be more complex than that of the cytoplasm. 相似文献
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