505 research outputs found
Solution Structure of LC4 Transmembrane Segment of CCR5
CC-chemokine receptor 5 (CCR5) is a specific co-receptor allowing the entry of human immunodeficiency virus type 1 (HIV-1). The LC4 region in CCR5 is required for HIV-1 entry into the cells. In this study, the solution structure of LC4 in SDS micelles was elucidated by using standard 1H two-dimensional NMR spectroscopy, circular dichroism, and fluorescdence quenching. The LC4 structure adopts two helical structures, whereas the C-terminal part remains unstructured. The positions in which LC4 binds to the HIV-1 inhibitory peptide LC5 were determined by docking calculations in addition to NMR data. The poses showed the importance of the hydrophobic interface of the assembled structures. The solution structure of LC4 elucidated in the present work provides a structural basis for further studies on the HIV-1 inhibitory function of the LC4 region
The prognostic value of the hypoxia markers CA IX and GLUT 1 and the cytokines VEGF and IL 6 in head and neck squamous cell carcinoma treated by radiotherapy ± chemotherapy
BACKGROUND: Several parameters of the tumor microenvironment, such as hypoxia, inflammation and angiogenesis, play a critical role in tumor aggressiveness and treatment response. A major question remains if these markers can be used to stratify patients to certain treatment protocols. The purpose of this study was to investigate the inter-relationship and the prognostic significance of several biological and clinicopathological parameters in patients with head and neck squamous cell carcinoma (HNSCC) treated by radiotherapy ± chemotherapy. METHODS: We used two subgroups of a retrospective series for which CT-determined tumoral perfusion correlated with local control. In the first subgroup (n = 67), immunohistochemistry for carbonic anhydrase IX (CA IX) and glucose transporter-1 (GLUT-1) was performed on the pretreatment tumor biopsy. In the second subgroup (n = 34), enzyme linked immunosorbent assay (ELISA) was used to determine pretreatment levels of the cytokines vascular endothelial growth factor (VEGF) and interleukin-6 (IL-6) in serum. Correlation was investigated between tumoral perfusion and each of these biological markers, as well as between the markers mutually. The prognostic value of these microenvironmental parameters was also evaluated. RESULTS: For CA IX and GLUT-1, the combined assessment of patients with both markers expressed above the median showed an independent correlation with local control (p = 0.02) and disease-free survival (p = 0.04) with a trend for regional control (p = 0.06). In the second subgroup, IL-6 pretreatment serum level above the median was the only independent predictor of local control (p = 0.009), disease-free survival (p = 0.02) and overall survival (p = 0.005). CONCLUSION: To our knowledge, we are the first to report a link in HNSCC between IL-6 pretreatment serum levels and radioresistance in vivo. This link is supported by the strong prognostic association of pretreatment IL-6 with local control, known to be the most important parameter to judge radiotherapy responses. Furthermore, the combined assessment of CA IX and GLUT-1 correlated independently with prognosis. This is a valuable indication that a combined approach is important in the investigation of prognostic markers
Sperm is epigenetically programmed to regulate gene transcription in embryos.
For a long time, it has been assumed that the only role of sperm at fertilization is to introduce the male genome into the egg. Recently, ideas have emerged that the epigenetic state of the sperm nucleus could influence transcription in the embryo. However, conflicting reports have challenged the existence of epigenetic marks on sperm genes, and there are no functional tests supporting the role of sperm epigenetic marking on embryonic gene expression. Here, we show that sperm is epigenetically programmed to regulate embryonic gene expression. By comparing the development of sperm- and spermatid-derived frog embryos, we show that the programming of sperm for successful development relates to its ability to regulate transcription of a set of developmentally important genes. During spermatid maturation into sperm, these genes lose H3K4me2/3 and retain H3K27me3 marks. Experimental removal of these epigenetic marks at fertilization de-regulates gene expression in the resulting embryos in a paternal chromatin-dependent manner. This demonstrates that epigenetic instructions delivered by the sperm at fertilization are required for correct regulation of gene expression in the future embryos. The epigenetic mechanisms of developmental programming revealed here are likely to relate to the mechanisms involved in transgenerational transmission of acquired traits. Understanding how parental experience can influence development of the progeny has broad potential for improving human health.We thank: T. Jenuwein and N. Shukeir for anti-H3K27me3 antibody; A. Bannister, J.
Ahringer and E. Miska for comments on the manuscript; Gurdon group members for reading
the manuscript; The International Xenopus laevis Genome Project Consortium (the Harland,
Rokhsar, Taira labs and others) for providing unpublished genome and gene annotation
information. M.T. is supported by WT089613 and by MR/K011022/1. V.G. and P.Z. are
funded by AICR 10-0908. A.S. is supported by MR/K011022/1. K.M. is a Research Fellow
at Wolfson College and is supported by the Herchel Smith Postdoctoral Fellowship. E.M.M.
is supported by National Institutes of Health, National Science Foundation, Cancer
Prevention Research Institute of Texas, and the Welch Foundation (F1515). J.J. and J.B.G.
are supported by WT101050/Z/13/Z. S.E. acknowledges Boehringer Ingelheim Fond
fellowship. A.H.F.M.P. is supported by the Swiss National Science Foundation
(31003A_125386) and the Novartis Research Foundation. All members of the Gurdon
Institute acknowledge the core support provided by CRUK C6946/A14492 and WT092096.This is the final version of the article. It first appeared from Cold Spring Harbor Laboratory Press via https://doi.org/10.1101/gr.201541.11
Plasma fibrinogen and risk of vascular recurrence after ischaemic stroke:An individual participant and summary-level data meta-analysis of 11 prospective studies
INTRODUCTION: Inflammation is an emerging target for secondary prevention after stroke and randomised trials of anti-inflammatory therapies are ongoing. Fibrinogen, a putative pro-inflammatory marker, is associated with first stroke, but its association with major adverse cardiovascular events (MACE) after stroke is unclear.MATERIALS AND METHODS: We did a systematic review investigating the association between fibrinogen and post-stroke vascular recurrence. Authors were invited to provide individual-participant data (IPD) and where available we did within-study multivariable analyses with adjustment for cardiovascular risk factors and medications. Adjusted summary-level data was extracted from published reports from studies that did not provide IPD. We pooled risk ratios (RR) by random-effects meta-analysis by comparing supra-median with sub-median fibrinogen levels and performed pre-specified subgroup analysis according to timing of phlebotomy after the index event.RESULTS: Eleven studies were included (14,002 patients, 42,800 follow-up years), of which seven provided IPD. Fibrinogen was associated with recurrent MACE on unadjusted (RR 1.35, 95% CI 1.17-1.57, supra-median vs sub-median) and adjusted models (RR 1.21, 95% CI 1.06-1.38). Fibrinogen was associated with recurrent stroke on univariate analysis (RR 1.19, 95% CI 1.03-1.39), but not after adjustment (RR 1.11, 95% CI 0.94-1.31). The association with recurrent MACE was consistently observed in patients with post-acute (⩾14 days) fibrinogen measures (RR 1.29, 95% CI 1.16-1.45), but not in those with early phlebotomy (<14 days) (RR 0.98, 95% CI 0.82-1.18) ( P interaction = 0.01). Similar associations were observed for recurrent stroke. DISCUSSION AND CONCLUSION: Fibrinogen was independently associated with recurrence after stroke, but the association was modified by timing of phlebotomy. Fibrinogen measurements might be useful to identify patients who are more likely to derive benefit from anti-inflammatory therapies after stroke.</p
Stellar Encounters with the Beta Pictoris Planetesimal System
We use data from the Hipparcos Catalog and the Barbier-Brossat & Figon (2000)
catalog of stellar radial velocities to test the hypothesis that the Beta Pic
planetesimal disk was disrupted by a close stellar encounter. We trace the
space motions of 21,497 stars and discover 18 that have passed within 5 pc of
Beta Pic in the past 1 Myr. Beta Pic's closest encounter is with the K2III star
HIP 27628 (0.6 pc), but dynamically the most important encounter is with the
F7V star HIP 23693 (0.9 pc). We calculate the velocity and eccentricity changes
induced by the 18 perturbations and conclude that they are dynamically
significant if planetesimals exist in a Beta Pic Oort cloud. We provide a
first-order estimate for the evolutionary state of a Beta Pic Oort cloud and
conclude that the primary role of these stellar perturbations would be to help
build a comet cloud rather than destroy a pre-existing structure. The stellar
sample is 20% complete and motivates future work to identify less common close
interactions that would significantly modify the observed circumstellar disk.
For future radial velocity study we identify six stars in the Hipparcos Catalog
that may have approached Beta Pic to within 0.1 pc and therefore remain as
candidate disk perturbers.Comment: 23 pages, 5 figures, Accepted for publication in Ap
Subcellular Localization of Hexokinases I and II Directs the Metabolic Fate of Glucose
The first step in glucose metabolism is conversion of glucose to glucose 6-phosphate (G-6-P) by hexokinases (HKs), a family with 4 isoforms. The two most common isoforms, HKI and HKII, have overlapping tissue expression, but different subcellular distributions, with HKI associated mainly with mitochondria and HKII associated with both mitochondrial and cytoplasmic compartments. Here we tested the hypothesis that these different subcellular distributions are associated with different metabolic roles, with mitochondrially-bound HK's channeling G-6-P towards glycolysis (catabolic use), and cytoplasmic HKII regulating glycogen formation (anabolic use).To study subcellular translocation of HKs in living cells, we expressed HKI and HKII linked to YFP in CHO cells. We concomitantly recorded the effects on glucose handling using the FRET based intracellular glucose biosensor, FLIPglu-600 mM, and glycogen formation using a glycogen-associated protein, PTG, tagged with GFP. Our results demonstrate that HKI remains strongly bound to mitochondria, whereas HKII translocates between mitochondria and the cytosol in response to glucose, G-6-P and Akt, but not ATP. Metabolic measurements suggest that HKI exclusively promotes glycolysis, whereas HKII has a more complex role, promoting glycolysis when bound to mitochondria and glycogen synthesis when located in the cytosol. Glycogen breakdown upon glucose removal leads to HKII inhibition and dissociation from mitochondria, probably mediated by increases in glycogen-derived G-6-P.These findings show that the catabolic versus anabolic fate of glucose is dynamically regulated by extracellular glucose via signaling molecules such as intracellular glucose, G-6-P and Akt through regulation and subcellular translocation of HKII. In contrast, HKI, which activity and regulation is much less sensitive to these factors, is mainly committed to glycolysis. This may be an important mechanism by which HK's allow cells to adapt to changing metabolic conditions to maintain energy balance and avoid injury
An axiomatization of the ratio/difference representation
If >=r and >=d are two quaternary relations on an arbitrary set A, a ratio/difference representation for >=r and >=d is defined to be a function f that represents >=r as an ordering of numerical ratios and >=d as an ordering of numerical differences. Krantz, Luce, Suppes and Tversky (1971, Foundations of Measurement. New York, Academic Press) proposed an axiomatization of the ratio/difference representation, but their axiomatization contains an error. After describing a counterexample to their axiomatization, Theorem 1 of the present article shows that it actually implies a weaker result: if >=r and >=d are two quaternary retations satisfying the axiomatization proposed by Krantz et al. (1971), and if >=r' and >=d' are the relations that are inverse to >=r and >=d, respectively, then either there exists a ratio/difference representation for >=r and >=d, or there exists a ratio/difference representation for >=r' and >=d', but not both. Theorem 2 identifies a new condition which, when added to the axioms of Krantz et al. (1971), yields the existence of a ratio/difference representation for relations >=r and >=d.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25051/1/0000479.pd
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