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1.
Nora Goosen Harold P. A. Horsman René G. M. Huinen Arjan de Groot Pieter van de Putte 《Antonie van Leeuwenhoek》1989,56(1):85-91
From a gene bank of theAcinetobacter calcoaceticus genome a plasmid was isolated that complements four different classes of PQQ- mutants. Subclones of this plasmid revealed that the four corresponding PQQ genes are located on a fragment of 5 kilobases. The nucleotide sequence of this 5 kb fragment was determined and by means of Tn5 insertion mutants the reading frames of the PQQ genes could be identified. Three of the PQQ genes code for proteins of Mr 29700 (gene I), Mr 10800 (gene II) and Mr 43600 (gene III) respectively. In the DNA region where gene IV was mapped however the largest possible reading frame encodes for a polypeptide of only 24 amino acids. A possible role for this small polypeptide will be discussed. Finally we show that expression of the four PQQ genes inAcinetobacter lwoffi andEscherichia coli lead to the synthesis of the coenzyme in these organisms. 相似文献
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The use of 13C-n.m.r. spectroscopy to monitor alginate biosynthesis in mucoid Pseudomonas aeruginosa. 总被引:3,自引:0,他引:3 下载免费PDF全文
The biosynthesis of alginate by a mucoid strain of Pseudomonas aeruginosa, isolated from a cystic-fibrosis patient, was monitored by using 13C-n.m.r. spectroscopy of bacterial cultures incubated with 1-13C- or 2-13C-enriched fructose. When 1-13C- or 2-13C-enriched fructose was used as the precursor of alginate, enrichment with 13C in the constituent uronic acid monomers of the polysaccharide could only be detected in C-1 or C-2 respectively, indicating that alginate is synthesized in Ps. aeruginosa directly from fructose, with the hexose molecule being retained intact; this rules out the involvement of C3 intermediates, which occurs when glucose is the alginate precursor. The absence of detectable poly-L-gluluronate block sequences from the alginate of Ps. aeruginosa was confirmed, and it was shown that there is no modification of the arrangement of the constituent uronic acids between polymerization to form alginate and the appearance of the mature alginate in the extracellular medium. The 13C-n.m.r. data also provided independent evidence for acetylation on D-mannuronate residues and for the ratio of D-mannuronate to L-guluronate residues in newly synthesized alginate, which had previously been determined only for material secreted from bacteria into the extracellular medium. 相似文献
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Johannes W. S. A. Osterloh Arjan C. Videler Gina M. P. Rossi Sebastiaan P. J. van Alphen 《Tijdschrift voor gerontologie en geriatrie》2018,49(5):210-212
Behavioural counselling by nurses can enhance quality of life in elderly with a personality disorder. Although nurses have a crucial role in day-to-day treatment, there is a lack of evidence-based approaches. Based on the cognitive therapy, the treatment protocol Cognitive Model for Behavioural Interventions (CoMBI) provides an alternative nursing approach for personality disorders. 相似文献
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Mahban Irandoust Julian Alvarez Zarate Isabelle Hubeek Ellen M. van Beek Karin Schornagel Aart J. F. Broekhuizen Mercan Akyuz Arjan A. van de Loosdrecht Ruud Delwel Peter J. Valk Edwin Sonneveld Pamela Kearns Ursula Creutzig Dirk Reinhardt Eveline S. J. M. de Bont Eva A. Coenen Marry M. van den Heuvel-Eibrink C. Michel Zwaan Gertjan J. L. Kaspers Jacqueline Cloos Timo K. van den Berg 《PloS one》2013,8(1)
Background
Recent studies show the importance of interactions between CD47 expressed on acute myeloid leukemia (AML) cells and the inhibitory immunoreceptor, signal regulatory protein-alpha (SIRPα) on macrophages. Although AML cells express SIRPα, its function has not been investigated in these cells. In this study we aimed to determine the role of the SIRPα in acute myeloid leukemia.Design and Methods
We analyzed the expression of SIRPα, both on mRNA and protein level in AML patients and we further investigated whether the expression of SIRPα on two low SIRPα expressing AML cell lines could be upregulated upon differentiation of the cells. We determined the effect of chimeric SIRPα expression on tumor cell growth and programmed cell death by its triggering with an agonistic antibody in these cells. Moreover, we examined the efficacy of agonistic antibody in combination with established antileukemic drugs.Results
By microarray analysis of an extensive cohort of primary AML samples, we demonstrated that SIRPα is differentially expressed in AML subgroups and its expression level is dependent on differentiation stage, with high levels in FAB M4/M5 AML and low levels in FAB M0–M3. Interestingly, AML patients with high SIRPα expression had a poor prognosis. Our results also showed that SIRPα is upregulated upon differentiation of NB4 and Kasumi cells. In addition, triggering of SIRPα with an agonistic antibody in the cells stably expressing chimeric SIRPα, led to inhibition of growth and induction of programmed cell death. Finally, the SIRPα-derived signaling synergized with the activity of established antileukemic drugs.Conclusions
Our data indicate that triggering of SIRPα has antileukemic effect and may function as a potential therapeutic target in AML. 相似文献9.
Jens H. W. Pahl S. Eriaty N. Ruslan Kitty M. C. Kwappenberg Monique M. van Ostaijen-ten Dam Maarten J. D. van Tol Arjan C. Lankester Marco W. Schilham 《Cancer immunology, immunotherapy : CII》2013,62(7):1235-1247
Osteosarcoma and Ewing’s sarcoma tumor cells are susceptible to IL15-induced or antibody-mediated cytolytic activity of NK cells in short-term cytotoxicity assays. When encountering the tumor environment in vivo, NK cells may be in contact with tumor cells for a prolonged time period. We explored whether a prolonged interaction with sarcoma cells can modulate the activation and cytotoxic activity of NK cells. The 40 h coculture of NK cells with sarcoma cells reversibly interfered with the IL15-induced expression of NKG2D, DNAM-1 and NKp30 and inhibited the cytolytic activity of NK cells. The inhibitory effects on receptor expression required physical contact between NK cells and sarcoma cells and were independent of TGF-β. Five days pre-incubation of NK cells with IL15 prevented the down-regulation of NKG2D and cytolytic activity in subsequent cocultures with sarcoma cells. NK cell FcγRIIIa/CD16 receptor expression and antibody-mediated cytotoxicity were not affected after the coculture. Inhibition of NK cell cytotoxicity was directly linked to the down-regulation of the respective NK cell-activating receptors. Our data demonstrate that the inhibitory effects of sarcoma cells on the cytolytic activity of NK cells do not affect the antibody-dependent cytotoxicity and can be prevented by pre-activation of NK cells with IL15. Thus, the combination of cytokine-activated NK cells and monoclonal antibody therapy may be required to improve tumor targeting and NK cell functionality in the tumor environment. 相似文献
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BACKGROUND: Circulating tumor cells (CTCs) in patients with carcinomas are extremely rare. In metastatic breast cancer, the presence of >or=5 CTCs in 7.5 ml of blood has been associated with short survival. As this threshold has clinical implications, it is important to recognize the limitations associated with the detection and enumeration of CTCs. METHODS: Statistical analyses were performed on data generated from a multi-center clinical trial that utilized the CellSearchtrade mark System to isolate and enumerate CTCs in 7.5 ml blood samples. The statistical issues associated with each step of the process, from blood collection to final image analysis and CTC enumeration, were determined and implemented into a model. RESULTS: A model describing the statistics of the different process steps that are needed for the isolation and detection of CTCs was developed. The model uses the Poisson distribution for blood collection and empirically determined distributions for the isolation and identification of CTCs. The variability between readers was identified as one of the main sources of errors responsible for the current threshold level of five CTCs. CONCLUSIONS: Elimination of the errors made in the identification of tumor cells isolated from 7.5 ml of blood could potentially reduce the CTC threshold for the identification of patients with a poor prognosis from the current value of five CTCs to one CTC per 7.5 ml of blood. 相似文献