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21.
Durrant JR Klug DR Kwa SL van Grondelle R Porter G Dekker JP 《Proceedings of the National Academy of Sciences of the United States of America》1995,92(11):4798-4802
We consider a model of the photosystem II (PS II) reaction center in which its spectral properties result from weak (approximately 100 cm-1) excitonic interactions between the majority of reaction center chlorins. Such a model is consistent with a structure similar to that of the reaction center of purple bacteria but with a reduced coupling of the chlorophyll special pair. We find that this model is consistent with many experimental studies of PS II. The similarity in magnitude of the exciton coupling and energetic disorder in PS II results in the exciton states being structurally highly heterogeneous. This model suggests that P680, the primary electron donor of PS II, should not be considered a dimer but a multimer of several weakly coupled pigments, including the pheophytin electron acceptor. We thus conclude that even if the reaction center of PS II is structurally similar to that of purple bacteria, its spectroscopy and primary photochemistry may be very different. 相似文献
22.
Translocation of the ETO gene on human chromosome 8 with the AML1 gene on chromosome 21 (AML1-ETO) is a recurrent cytogenetic abnormality associated with approximately 12% of acute myelogenous leukemia (AML) cases. To understand the contribution of the t(8;21) to AML, we transduced purified hematopoietic stem cells (HSC) with a retroviral vector that coexpressed AML1-ETO or just the AML1 portion (AML1d) of the translocation along with a green fluorescent protein reporter gene. Animals reconstituted with AML1-ETO-expressing cells exhibited many of the hematopoietic developmental abnormalities seen in the bone marrow of human patients with the t(8;21), although the animals did not develop acute leukemia. We noted a gradual increase in primitive myeloblasts that accounted for approximately 10% of bone marrow by 10 months posttransplant. Consistent with this observation was a 50-fold increase in myeloid colony-forming cells in vitro. In addition, accumulation of late stage metamyelocytes was observed in bone marrow along with an increase in immature eosinophil myelocytes that showed abnormal basophilic granulation. There was also a gradual increase in both the frequency and absolute number of AML1-ETO-expressing HSC so that by 10 months posttransplant, there were 29-fold greater HSC numbers than in transplant-matched control mice. These phenotypes were not observed in animals reconstituted with cells expressing only the DNA-binding domain of AML1, suggesting that the ETO domain is necessary to establish the developmental abnormalities associated with AML1-ETO expression in HSC. 相似文献
23.
24.
Klug Tejs Ehlers Greve Thomas Andersen Camilla Hahn Pernille Danstrup Christian Petersen Niels Krintel Ninn-Pedersen Mirjana Mikkelsen Sophie Pauli Søren Fuglsang Simon Døssing Helle Christensen Anne-Louise Rusan Maria Kjeldsen Anette 《European journal of clinical microbiology & infectious diseases》2021,40(7):1461-1470
European Journal of Clinical Microbiology & Infectious Diseases - We aimed to describe the microbiology of parapharyngeal abscess (PPA) and point out the likely pathogens using the following... 相似文献
25.
Dawn Peck Amy White Gisele Pino April Studinski Meghan Strenk Randi Gadea Jennifer Gannon Bryce Heese Esperanza Font-Montgomery Tracy Klug Jennifer Burton George Hoganson Devin Oglesbee Dimitar Gavrilov Dietrich Matern Kimiyo Raymond Piero Rinaldo Silvia Tortorelli 《Molecular genetics and metabolism》2021
26.
Heun Jin Lee Eric L. Peterson Rob Phillips William S. Klug Paul A. Wiggins 《Proceedings of the National Academy of Sciences of the United States of America》2008,105(49):19253-19257
Recent advances have enabled 3-dimensional reconstructions of biological structures in vivo, ranging in size and complexity from single proteins to multicellular structures. In particular, tomography and confocal microscopy have been exploited to capture detailed 3-dimensional conformations of membranes in cellular processes ranging from viral budding and organelle maintenance to phagocytosis. Despite the wealth of membrane structures available, there is as yet no generic, quantitative method for their interpretation. We propose that by modeling these observed biomembrane shapes as fluid lipid bilayers in mechanical equilibrium, the externally applied forces as well as the pressure, tension, and spontaneous curvature can be computed directly from the shape alone. To illustrate the potential power of this technique, we apply an axial force with optical tweezers to vesicles and explicitly demonstrate that the applied force is equal to the force computed from the membrane conformation. 相似文献
27.
T. E. Klug J.-J. Henriksen M. Rusan K. Fuursted K. A. Krogfelt T. Ovesen C. Struve 《European journal of clinical microbiology & infectious diseases》2014,33(10):1733-1739
A polymicrobial mixture of aerobic and anaerobic bacteria is commonly recovered from peritonsillar abscess (PTA) aspirates. Previous studies have suggested a role for Fusobacterium necrophorum (FN) in the development of PTA. The purpose of the current study was to explore whether anti-FN antibodies were produced in patients with PTA. We developed a novel immunofluorescence-based method to measure anti-FN antibody levels in acute and convalescent sera from 15 patients with PTA and 47 patients with chronic tonsillar conditions (controls) undergoing acute or elective tonsillectomy, respectively. Bacterial cultures were performed on tonsillar cores and surfaces, pus aspirates, and blood. An increase in anti-FN antibody levels (of at least doubling of the previous level) was observed in 8 of 11 (73 %) PTA patients with FN-positive pus aspirate cultures (FN-positive patients). In contrast, the four FN-negative PTA patients did not have an increase in anti-FN antibody levels (p?=?0.026). The change in anti-FN antibody levels in FN-positive PTA patients was also significantly greater than that for FN-positive electively tonsillectomized patients (p?=?0.0014) and all electively tonsillectomized patients (p?0.001). Our results validate FN as a significant and prevalent pathogen in PTA. This finding has implications for the diagnostic work-up of PTA and may also have implications for the treatment of acute tonsillitis. 相似文献
28.
Wills TA Klug JR Silberman Y Baucum AJ Weitlauf C Colbran RJ Delpire E Winder DG 《Proceedings of the National Academy of Sciences of the United States of America》2012,109(5):E278-E287
The bed nucleus of the stria terminalis (BNST) is a critical region for alcohol/drug-induced negative affect and stress-induced reinstatement. NMDA receptor (NMDAR)-dependent plasticity, such as long-term potentiation (LTP), has been postulated to play key roles in alcohol and drug addiction; yet, to date, little is understood regarding the mechanisms underlying LTP of the BNST, or its regulation by ethanol. Acute and chronic exposure to ethanol modulates glutamate transmission via actions on NMDARs. Despite intense investigation, tests of subunit specificity of ethanol actions on NMDARs using pharmacological approaches have produced mixed results. Thus, we use a conditional GluN2B KO mouse line to assess both basal and ethanol-dependent function of this subunit at glutamate synapses in the BNST. Deletion of GluN2B eliminated LTP, as well as actions of ethanol on NMDAR function. Further, we show that chronic ethanol exposure enhances LTP formation in the BNST. Using KO-validated pharmacological approaches with Ro25-6981 and memantine, we provide evidence suggesting that chronic ethanol exposure enhances LTP in the BNST via paradoxical extrasynaptic NMDAR involvement. These findings demonstrate that GluN2B is a key point of regulation for ethanol's actions and suggest a unique role of extrasynaptic GluN2B-containing receptors in facilitating LTP. 相似文献
29.
The t(8;21) RUNX1-ETO translocation is one of the most frequent cytogenetic abnormalities in acute myeloid leukemia (AML). In RUNX1-ETO(+) patient samples, differing classes of activating c-KIT receptor tyrosine kinase mutations have been observed. The most common (12%-48%) involves mutations, such as D816V, which occur in the tyrosine kinase domain, whereas another involves mutations within exon 8 in a region mediating receptor dimerization (2%-13% of cases). To test whether distinct subtypes of activating c-KIT mutations differ in their leukemogenic potential in association with RUNX1-ETO, we used a retroviral transduction/transplantation model to coexpress RUNX1-ETO with either c-Kit(D814V) or c-Kit(T417IΔ418-419) in murine hematopoietic stem/progenitor cells used to reconstitute lethally irradiated mice. Analysis of reconstituted animals showed that RUNX1-ETO;c-Kit(D814V) coexpression resulted in 3 nonoverlapping phenotypes. In 45% of animals, a transplantable AML of relatively short latency and frequent granulocytic sarcoma was noted. Other mice exhibited a rapidly fatal myeloproliferative phenotype (35%) or a lethal, short-latency pre-B-cell leukemia (20%). In contrast, RUNX1-ETO;c-Kit(T417IΔ418-419) coexpression promoted exclusively AML in a fraction (51%) of reconstituted mice. These observations indicate that c-Kit(D814V) promotes a more varied and aggressive leukemic phenotype than c-Kit(T417IΔ418-419), which may be the result of differing potencies of the activating c-Kit alleles. 相似文献
30.
Parents’ and Adolescents’ Preferences for Intensified or Reduced Treatment in Randomized Lymphoblastic Leukemia Trials
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