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Find video protocols related to scientific articles indexed in Pubmed.
Elevated TAK1 augments tumor growth and metastatic capacities of ovarian cancer cells through activation of NF-?B signaling.
Oncotarget
PUBLISHED: 10-04-2014
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Transforming growth factor (TGF)-?-activating kinase 1 (TAK1) is a serine/threonine kinase which is frequently associated with human cancer progression. However, its functional role in tumorigenesis is still controversial. Here, we report that TAK1 enhances the oncogenic capacity of ovarian cancer cells through the activation of NF-?B signaling. We found that TAK1 is frequently upregulated and significantly associated with high-grade and metastatic ovarian cancers. Mechanistic studies showed that Ser412 phosphorylation is required for TAK1 in activating NF-?B signaling and promotes aggressiveness of ovarian cancer cells. Conversely, suppression of TAK1 activity by point mutation at Ser412, RNAi mediated gene knockdown or TAK1 specific inhibitor ((5Z) -7-Oxozeaenol) remarkably impairs tumor growth and metastasis in ovarian cancer in vitro and in vivo. Our study underscores the importance of targeting TAK1 as a promising therapeutic approach to counteract the ovarian cancer progression.
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Mitochondrial dynamics and inheritance during cell division, development and disease.
Nat. Rev. Mol. Cell Biol.
PUBLISHED: 09-17-2014
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During cell division, it is critical to properly partition functional sets of organelles to each daughter cell. The partitioning of mitochondria shares some common features with that of other organelles, particularly in the use of interactions with cytoskeletal elements to facilitate delivery to the daughter cells. However, mitochondria have unique features - including their own genome and a maternal mode of germline transmission - that place additional demands on this process. Consequently, mechanisms have evolved to regulate mitochondrial segregation during cell division, oogenesis, fertilization and tissue development, as well as to ensure the integrity of these organelles and their DNA, including fusion-fission dynamics, organelle transport, mitophagy and genetic selection of functional genomes. Defects in these processes can lead to cell and tissue pathologies.
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The Impact of Massachusetts Health Care Reform on Access, Quality, and Costs of Care for the Already-Insured.
Health Serv Res
PUBLISHED: 09-16-2014
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To assess the impact of Massachusetts Health Reform (MHR) on access, quality, and costs of outpatient care for the already-insured.
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Syntactic and discourse skills in Chinese adolescent readers with dyslexia: a profiling study.
Ann Dyslexia
PUBLISHED: 06-24-2014
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This study aims to investigate the relation of syntactic and discourse skills to morphological skills, rapid naming, and working memory in Chinese adolescent readers with dyslexia and to examine their cognitive-linguistic profiles. Fifty-two dyslexic readers (mean age, 13;42) from grade 7 to 9 in Hong Kong high schools were compared with 52 typically developing readers of the same chronological age (mean age, 13;30) in the measures of word reading, 1-min word reading, reading comprehension, morpheme discrimination, morpheme production, morphosyntactic knowledge, sentence order knowledge, digit rapid naming, letter rapid naming, backward digit span, and non-word repetition. Results showed that dyslexic readers performed significantly worse than their peers on all the cognitive-linguistic tasks. Analyses of individual performance also revealed that over half of the dyslexic readers exhibited deficits in syntactic and discourse skills. Moreover, syntactic skills, morphological skills, and rapid naming best distinguished dyslexic from non-dyslexic readers. Findings underscore the significance of syntactic and discourse skills for understanding reading impairment in Chinese adolescent readers.
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The Concept of Human Dignity in the Ethics of Genetic Research.
Bioethics
PUBLISHED: 06-10-2014
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Despite criticism that dignity is a vague and slippery concept, a number of international guidelines on bioethics have cautioned against research that is contrary to human dignity, with reference specifically to genetic technology. What is the connection between genetic research and human dignity? In this article, I investigate the concept of human dignity in its various historical forms, and examine its status as a moral concept. Unlike Kant's ideal concept of human dignity, the empirical or relational concept takes human dignity as something that is affected by one's circumstances and what others do. I argue that the dignity objection to some forms of genetic research rests on a view of human nature that gives humans a special status in nature - one that is threatened by the potential of genetic research to reduce individuals to their genetic endowment. I distinguish two main philosophical accounts of human nature. One of these, the Aristotelian view, is compatible with the use of genetic technology to help humans realize their inherent potential to a fuller extent.
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Degradation of the deubiquitinating enzyme USP33 is mediated by p97 and the ubiquitin ligase HERC2.
J. Biol. Chem.
PUBLISHED: 05-22-2014
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Because the deubiquitinating enzyme USP33 is involved in several important cellular processes (?-adrenergic receptor recycling, centrosome amplification, RalB signaling, and cancer cell migration), its levels must be carefully regulated. Using quantitative mass spectrometry, we found that the intracellular level of USP33 is highly sensitive to the activity of p97. Knockdown or chemical inhibition of p97 causes robust accumulation of USP33 due to inhibition of its degradation. The p97 adaptor complex involved in this function is the Ufd1-Npl4 heterodimer. Furthermore, we identified HERC2, a HECT domain-containing E3 ligase, as being responsible for polyubiquitination of USP33. Inhibition of p97 causes accumulation of polyubiquitinated USP33, suggesting that p97 is required for postubiquitination processing. Thus, our study has identified several key molecules that control USP33 degradation within the ubiquitin-proteasome system.
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Adjunctive procedures to neck rejuvenation.
Facial Plast Surg Clin North Am
PUBLISHED: 04-22-2014
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Rejuvenation of the neck often requires more than just a neck lift. Various steps and procedures exist to enhance the surgical technique or overall result. Fibrin sealants can be used to improve the recovery process and obviate the need for drain placement. Chin augmentation can be a critical part of creating a more refined neckline. Submandibular gland excision has been put forth as helpful to the overall aesthetic result. A low and anteriorly positioned hyoid bone creates an unattractive neckline that is difficult to treat. This article focuses on techniques beyond lifting and resurfacing that may enhance neck rejuvenation.
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Prognostic significance of novel ¹?F-FDG PET/CT defined tumour variables in patients with oesophageal cancer.
Eur J Radiol
PUBLISHED: 03-27-2014
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(18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET) combined with computed tomography (PET/CT) is now established as a routine staging investigation of oesophageal cancer (OC). The aim of the study was to determine the prognostic significance of PET/CT defined tumour variables including maximum standardised uptake value (SUVmax), tumour length (TL), metastatic length of disease (MLoD), metabolic tumour volume (MTV), total lesion glycolysis (TLG) and total local nodal metastasis count (PET/CT LNMC).
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Epigenetic silencing of microRNA-199b-5p is associated with acquired chemoresistance via activation of JAG1-Notch1 signaling in ovarian cancer.
Oncotarget
PUBLISHED: 03-25-2014
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Epithelial ovarian cancer is a highly lethal and aggressive gynecological malignancy. The high mortality rate is due in part to the fact that many advanced cancer patients become refractory to current chemotherapeutic agents, leading to tumor recurrence and death. However, the underlying mechanisms leading to chemoresistance remain obscure. Here, we report that the loss of miR-199b-5p due to progressive epigenetic silencing leads to the activation of the JAG1-mediated Notch1 signaling cascade, thereby leading to the development of acquired chemoresistance in ovarian cancer. Using miRCURY LNA™ microRNA array and Q-PCR analyses of two pairs of cisplatin-sensitive and -resistant ovarian cancer cell lines, we identified miR-199b-5p as significantly down-regulated in cisplatin-resistant ovarian cancer cells and confirmed that miR-199b-5p is clinically associated with advanced and poor survival ovarian cancers. Interestingly, the loss of miR-199b-5p could be restored by 5-Aza-dC-mediated demethylation, and methylated specific PCR (MS-PCR), bisulfite-sequencing and pyrosequencing revealed that the promoter region of miR-199b-5p was hypermethylated. Computational and mechanistic analyses identified JAG1 as a primary target of miR-199b-5p. Notably, the reduced expression of miR-199b-5p was found to be inversely correlated with the increased expression of JAG1 using an ovarian cancer tissue array. Enforced expression of miR-199b-5p sensitized ovarian cancer cells to cisplatin-induced cytotoxicity both in vitro and in vivo. Conversely, re-expression of miR-199b-5p and siRNA-mediated JAG1 knockdown or treatment with Notch specific inhibitor ?-secretase (GSI) attenuated JAG1-Notch1 signaling activity, thereby enhancing cisplatin-mediated cell cytotoxicity. Taken together, our study suggests that the epigenetic silencing of miR-199b-5p during tumor progression is significantly associated with acquired chemoresistance in ovarian cancer through the activation of JAG1-Notch1 signaling.
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Reduced expression of AMPK-?1 during tumor progression enhances the oncogenic capacity of advanced ovarian cancer.
Mol. Cancer
PUBLISHED: 02-21-2014
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AMP-activated protein kinase (AMPK) is a key energy sensor that is involved in regulating cell metabolism. Our previous study revealed that the subunits of the heterotimeric AMPK enzyme are diversely expressed during ovarian cancer progression. However, the impact of the variable expression of these AMPK subunits in ovarian cancer oncogenesis remains obscure. Here, we provide evidence to show that reduced expression of the AMPK-?1 subunit during tumor progression is associated with the increased oncogenic capacity of advanced ovarian cancer cells. Immunohistochemical analysis revealed that AMPK-?1 levels were reduced in advanced-stage (P = 0.008), high-grade (P = 0.013) and metastatic ovarian cancers (P = 0.008). Intriguingly, down-regulation of AMPK-?1 was progressively reduced from tumor stages 1 to 3 of ovarian cancer. Functionally, enforced expression of AMPK-?1 inhibited ovarian-cancer-cell proliferation, anchorage-independent cell growth, cell migration and invasion. Conversely, depletion of AMPK-?1 by siRNA enhanced the oncogenic capacities of ovarian cancer cells, suggesting that the loss of AMPK-?1 favors the aggressiveness of ovarian cancer. Mechanistically, enforced expression of AMPK-?1 increased AMPK activity, which, in turn, induced cell-cycle arrest via inhibition of AKT/ERK signaling activity as well as impaired cell migration/invasion through the suppression of JNK signaling in ovarian cancer cells. Taken together, these findings suggest that the reduced expression of AMPK-?1 confers lower AMPK activity, which enhances the oncogenic capacity of advanced-stage ovarian cancer.
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Physical function and quality of life in frail and/or elderly patients with metastatic colorectal cancer treated with capecitabine and bevacizumab: An exploratory analysis.
J Geriatr Oncol
PUBLISHED: 02-17-2014
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Optimal treatment strategies in frail and/or elderly patients with metastatic colorectal cancer have not been well defined. Using data from a prospective, phase II study of elderly patients with metastatic colorectal cancer treated with bevacizumab and capecitabine, we explored the differences in functional measure and quality of life (QoL) between patients with ECOG performance status (PS) 1 and 2.
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Improving outcomes by combining septoplasty with primary external dacryocystorhinostomy.
Am J Otolaryngol
PUBLISHED: 02-03-2014
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External dacryocystorhinostomy (EXT-DCR) is the gold standard in the treatment of acquired nasolacrimal duct obstruction. Intranasal pathology can compromise the success of primary and revision external dacryocystorhinostomy EXT-DCR procedures. Nasal septal deviations resulting in unfavorable anatomy are an identified cause of DCR failures. In this study, we examine the causes of failure in our patient population and propose that concomitant treatment of septal deviations at the time of primary EXT-DCR can decrease the rate of revision surgery.
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Endoscopic endonasal transplanum transtuberculum resection of a large solid choroid plexus papilloma of the third ventricle.
J Clin Neurosci
PUBLISHED: 02-01-2014
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Choroid plexus papilloma (CPP) is a highly vascular solid or mixed solid-cystic tumor. Previously described resection techniques for the more common solid CPP in the third ventricle have all been through the transcranial route. The authors review the literature and describe a patient who, to their knowledge, is the first successful resection of a large, completely solid CPP of the third ventricle through an entirely endoscopic, extended transphenoidal approach. Using modern neuroendoscopic methods and closure techniques, a gross total resection was accomplished and a successful closure without postoperative cerebrospinal fluid leak was achieved despite the presence of preoperative hydrocephalus. For appropriately selected lesions, an extended endonasal skull base resection can be performed successfully for vascular tumors despite the presence of preoperative hydrocephalus.
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Proteolytic cleavage of Opa1 stimulates mitochondrial inner membrane fusion and couples fusion to oxidative phosphorylation.
Cell Metab.
PUBLISHED: 01-27-2014
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Mitochondrial fusion is essential for maintenance of mitochondrial function. The mitofusin GTPases control mitochondrial outer membrane fusion, whereas the dynamin-related GTPase Opa1 mediates inner membrane fusion. We show that mitochondrial inner membrane fusion is tuned by the level of oxidative phosphorylation (OXPHOS), whereas outer membrane fusion is insensitive. Consequently, cells from patients with pathogenic mtDNA mutations show a selective defect in mitochondrial inner membrane fusion. In elucidating the molecular mechanism of OXPHOS-stimulated fusion, we uncover that real-time proteolytic processing of Opa1 stimulates mitochondrial inner membrane fusion. OXPHOS-stimulated mitochondrial fusion operates through Yme1L, which cleaves Opa1 more efficiently under high OXPHOS conditions. Engineered cleavage of Opa1 is sufficient to mediate inner membrane fusion, regardless of respiratory state. Proteolytic cleavage therefore stimulates the membrane fusion activity of Opa1, and this feature is exploited to dynamically couple mitochondrial fusion to cellular metabolism.
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Physician surveillance of influenza: collaboration between primary care and public health.
Can Fam Physician
PUBLISHED: 01-24-2014
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Influenza-like illness (ILI) is a global and national concern. The surveillance of ILI requires collaborative efforts from many diverse settings, including primary care clinics.
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Distinct structural features of TFAM drive mitochondrial DNA packaging versus transcriptional activation.
Nat Commun
PUBLISHED: 01-18-2014
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TFAM (transcription factor A, mitochondrial) is a DNA-binding protein that activates transcription at the two major promoters of mitochondrial DNA (mtDNA)--the light strand promoter (LSP) and the heavy strand promoter 1 (HSP1). Equally important, it coats and packages the mitochondrial genome. TFAM has been shown to impose a U-turn on LSP DNA; however, whether this distortion is relevant at other sites is unknown. Here we present crystal structures of TFAM bound to HSP1 and to nonspecific DNA. In both, TFAM similarly distorts the DNA into a U-turn. Yet, TFAM binds to HSP1 in the opposite orientation from LSP explaining why transcription from LSP requires DNA bending, whereas transcription at HSP1 does not. Moreover, the crystal structures reveal dimerization of DNA-bound TFAM. This dimerization is dispensable for DNA bending and transcriptional activation but is important in DNA compaction. We propose that TFAM dimerization enhances mitochondrial DNA compaction by promoting looping of the DNA.
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What are the early indicators of persistent word reading difficulties among Chinese readers in elementary grades?
Dyslexia
PUBLISHED: 01-09-2014
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To identify the indicators of persistent reading difficulties among Chinese readers in early elementary grades, the performance of three groups of Chinese children with different reading trajectories ('persistent poor word readers', 'improved poor word readers' and 'skilled word readers') in reading-related measures was analysed in a 3-year longitudinal study. The three groups were classified according to their performance in a standardized Chinese word reading test in Grade 1 and Grade 4. Results of analysis of variance and logistic regression on the reading-related measures revealed that rapid naming and syntactic skills were important indicators of early word reading difficulty. Syntactic skills and morphological awareness were possible markers of persistent reading problems. Chinese persistent poor readers did not differ significantly from skilled readers on the measures of phonological skills.
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The mitochondrial fission receptor MiD51 requires ADP as a cofactor.
Structure
PUBLISHED: 01-02-2014
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Mitochondrial fission requires recruitment of dynamin-related protein 1 (Drp1) to the mitochondrial surface and activation of its GTP-dependent scission function. The Drp1 receptors MiD49 and MiD51 recruit Drp1 to facilitate mitochondrial fission, but their mechanism of action is poorly understood. Using X-ray crystallography, we demonstrate that MiD51 contains a nucleotidyl transferase domain that binds ADP with high affinity. MiD51 recruits Drp1 via a surface loop that functions independently of ADP binding. However, in the absence of nucleotide binding, the recruited Drp1 cannot be activated for fission. Purified MiD51 strongly inhibits Drp1 assembly and GTP hydrolysis in the absence of ADP. Addition of ADP relieves this inhibition and promotes Drp1 assembly into spirals with enhanced GTP hydrolysis. Our results reveal ADP as an essential cofactor for MiD51 during mitochondrial fission.
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Cardiac safety results from a phase II, open-label, multicenter, pilot study of two docetaxel-based regimens plus bevacizumab for the adjuvant treatment of subjects with node-positive or high-risk node-negative breast cancer.
Springerplus
PUBLISHED: 01-01-2014
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Adding antiangiogenic therapy to standard chemotherapy has improved response rates and progression-free survival in metastatic breast cancer (BC) patients. This phase II study evaluated cardiac safety of bevacizumab with/without trastuzumab with two docetaxel-based regimens in early BC.
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Targeting estrogen receptor subtypes (ER? and ER?) with selective ER modulators in ovarian cancer.
J. Endocrinol.
PUBLISHED: 01-01-2014
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Ovarian cancer cells express both estrogen receptor ? (ER?) and ER?, and hormonal therapy is an attractive treatment option because of its relatively few side effects. However, estrogen was previously shown to have opposite effects in tumors expressing ER? compared with ER?, indicating that the two receptor subtypes may have opposing effects. This may explain the modest response to nonselective estrogen inhibition in clinical practice. In this study, we aimed to investigate the effect of selectively targeting each ER subtype on ovarian cancer growth. Ovarian cancer cell lines SKOV3 and OV2008, expressing both ER subtypes, were treated with highly selective ER modulators. Sodium 3'-(1-(phenylaminocarbonyl)-3,4-tetrazolium)-bis(4-methoxy-6-nitro) benzene sulfonic acid hydrate (XTT) assay revealed that treatment with 1,3-bis(4-hydroxyphenyl)-4-methyl-5-[4-(2-piperidinylethoxy)phenol]-1H-pyrazole dihydrochloride (MPP) (ER? antagonist) or 2,3-bis(4-hydroxy-phenyl)-propionitrile (DPN) (ER? agonist) significantly suppressed cell growth in both cell lines. In contrast, 4,4',4?-(4-propyl-[1H]-pyrazole-1,3,5-triyl) trisphenol (PPT) (ER? agonist) or 4-[2-phenyl-5,7-bis(trifluoromethyl)pyrazolo[1,5-a]-pyrimidin-3-yl]phenol (PHTPP) (ER? antagonist) significantly enhanced cell growth. These results were confirmed on a xenograft model where SKOV3 cells were injected s.c. into ovariectomized mice. We observed that the average size of xenografts in both the DPN-treated group and the MPP-treated group was significantly smaller than that for the vehicle-treated group. In addition, we found that phospho-AKT expressions in SKOV3 cells were reduced by 80% after treatment with MPP and DPN, indicating that the AKT pathway was involved. The combined treatment with MPP and DPN had a synergistic effect in suppressing ovarian cancer cell growth. Our findings indicate that targeting ER subtypes may enhance the response to hormonal treatment in women with ovarian cancer.
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Stimulus familiarity modulates functional connectivity of the perirhinal cortex and anterior hippocampus during visual discrimination of faces and objects.
Front Hum Neurosci
PUBLISHED: 01-01-2014
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Recent research suggests that the medial temporal lobe (MTL) is involved in perception as well as in declarative memory. Amnesic patients with focal MTL lesions and semantic dementia patients showed perceptual deficits when discriminating faces and objects. Interestingly, these two patient groups showed different profiles of impairment for familiar and unfamiliar stimuli. For MTL amnesics, the use of familiar relative to unfamiliar stimuli improved discrimination performance. By contrast, patients with semantic dementia-a neurodegenerative condition associated with anterolateral temporal lobe damage-showed no such facilitation from familiar stimuli. Given that the two patient groups had highly overlapping patterns of damage to the perirhinal cortex, hippocampus, and temporal pole, the neuroanatomical substrates underlying their performance discrepancy were unclear. Here, we addressed this question with a multivariate reanalysis of the data presented by Barense et al. (2011), using functional connectivity to examine how stimulus familiarity affected the broader networks with which the perirhinal cortex, hippocampus, and temporal poles interact. In this study, healthy participants were scanned while they performed an odd-one-out perceptual task involving familiar and novel faces or objects. Seed-based analyses revealed that functional connectivity of the right perirhinal cortex and right anterior hippocampus was modulated by the degree of stimulus familiarity. For familiar relative to unfamiliar faces and objects, both right perirhinal cortex and right anterior hippocampus showed enhanced functional correlations with anterior/lateral temporal cortex, temporal pole, and medial/lateral parietal cortex. These findings suggest that in order to benefit from stimulus familiarity, it is necessary to engage not only the perirhinal cortex and hippocampus, but also a network of regions known to represent semantic information.
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Evidence for site-specific occupancy of the mitochondrial genome by nuclear transcription factors.
PLoS ONE
PUBLISHED: 01-01-2014
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Mitochondria contain their own circular genome, with mitochondria-specific transcription and replication systems and corresponding regulatory proteins. All of these proteins are encoded in the nuclear genome and are post-translationally imported into mitochondria. In addition, several nuclear transcription factors have been reported to act in mitochondria, but there has been no comprehensive mapping of their occupancy patterns and it is not clear how many other factors may also be found in mitochondria. Here we address these questions by using ChIP-seq data from the ENCODE, mouseENCODE and modENCODE consortia for 151 human, 31 mouse and 35 C. elegans factors. We identified 8 human and 3 mouse transcription factors with strong localized enrichment over the mitochondrial genome that was usually associated with the corresponding recognition sequence motif. Notably, these sites of occupancy are often the sites with highest ChIP-seq signal intensity within both the nuclear and mitochondrial genomes and are thus best explained as true binding events to mitochondrial DNA, which exist in high copy number in each cell. We corroborated these findings by immunocytochemical staining evidence for mitochondrial localization. However, we were unable to find clear evidence for mitochondrial binding in ENCODE and other publicly available ChIP-seq data for most factors previously reported to localize there. As the first global analysis of nuclear transcription factors binding in mitochondria, this work opens the door to future studies that probe the functional significance of the phenomenon.
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SIRT3 deacetylates and activates OPA1 to regulate mitochondrial dynamics during stress.
Mol. Cell. Biol.
PUBLISHED: 12-16-2013
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Mitochondrial morphology is regulated by the balance between two counteracting mitochondrial processes of fusion and fission. There is significant evidence suggesting a stringent association between morphology and bioenergetics of mitochondria. Morphological alterations in mitochondria are linked to several pathological disorders including cardiovascular diseases. Consequences of stress-induced acetylation of mitochondrial proteins on the organelle morphology remain largely unexplored. Here we report that OPA1, a mitochondrial fusion protein was hyper-acetylated in hearts under pathologic stress, and this post-translational modification reduced GTPase activity of the protein. The mitochondrial deacetylase SIRT3 was capable of deacetylating OPA1 and elevating its GTPase activity. The mass spectrometry and mutagenesis analyses indicated that in SIRT3-deficient cells OPA1 was acetylated at lysine 926 and 931 residues. Over expression of deacetylation-mimetic version of OPA1 recovered mitochondrial functions of OPA1 null cells, thus demonstrating functional significance of K926/931 acetylation in regulating OPA1 activity. Moreover, SIRT3-dependent activation of OPA1 contributed to preservation of mitochondrial networking and protection of cardiomyocytes from doxorubicin-mediated cell death. In summary, these data indicated that SIRT3 not only promotes mitochondrial function by regulating activity of metabolic enzymes as previously reported, but also by regulating mitochondrial dynamics by targeting OPA1.
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Recent trends in thyroid surgery in Wales.
Surgeon
PUBLISHED: 10-17-2013
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Our objective was to analyse trends in thyroid surgery in Wales over a recent 12-year period.
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Modeling the relationships between cognitive-linguistic skills and writing in Chinese among elementary grades students.
Read Writ
PUBLISHED: 07-16-2013
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The present study is a four-year longitudinal study examining the important predictors of writing of 340 Chinese children in elementary grades. Childrens transcription skills (handwriting skills and spelling), and syntactic skills in grade 1 were significant predictors of text writing in grade 1-4 while ideation in grade 1 only contributed to text writing in grade 2. Stroke order knowledge was shown as an important handwriting skill in Chinese reflecting the characteristics of the Chinese orthography. A model of Chinese writing in early elementary grades was proposed. In the model, orthographic knowledge, morphological awareness and handwriting skills are proposed to contribute to spelling which is correlated with text writing. Handwriting skills, ideation, and syntactic skills were found to contribute to text writing. Path analysis results suggest that the longitudinal relationship between spelling and text writing is bidirectional.
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Activation of AMPK inhibits cervical cancer cell growth through AKT/FOXO3a/FOXM1 signaling cascade.
BMC Cancer
PUBLISHED: 04-08-2013
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Although advanced-stage cervical cancer can benefit from current treatments, approximately 30% patients may fail after definitive treatment eventually. Therefore, exploring alternative molecular therapeutic approaches is imperatively needed for this disease. We have recently shown that activation of AMP-activated protein kinase (AMPK), a metabolic sensor, hampers cervical cancer cell growth through blocking the Wnt/?-catenin signaling activity. Here, we report that activated AMPK (p-AMPK) also inhibits cervical cancer cell growth by counteracting FOXM1 function.
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The histone demethylase Jmjd3 sequentially associates with the transcription factors Tbx3 and Eomes to drive endoderm differentiation.
EMBO J.
PUBLISHED: 03-13-2013
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Stem cell differentiation depends on transcriptional activation driven by lineage-specific regulators as well as changes in chromatin organization. However, the coordination of these events is poorly understood. Here, we show that T-box proteins team up with chromatin modifying enzymes to drive the expression of the key lineage regulator, Eomes during endodermal differentiation of embryonic stem (ES) cells. The Eomes locus is maintained in a transcriptionally poised configuration in ES cells. During early differentiation steps, the ES cell factor Tbx3 associates with the histone demethylase Jmjd3 at the enhancer element of the Eomes locus to allow enhancer-promoter interactions. This spatial reorganization of the chromatin primes the cells to respond to Activin signalling, which promotes the binding of Jmjd3 and Eomes to its own bivalent promoter region to further stimulate Eomes expression in a positive feedback loop. In addition, Eomes activates a transcriptional network of core regulators of endodermal differentiation. Our results demonstrate that Jmjd3 sequentially associates with two T-box factors, Tbx3 and Eomes to drive stem cell differentiation towards the definitive endoderm lineage.
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Insurance expansion in Massachusetts did not reduce access among previously insured Medicare patients.
Health Aff (Millwood)
PUBLISHED: 03-06-2013
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Critics of Massachusettss health reform, a model for the Affordable Care Act, have argued that insurance expansion probably had a negative spillover effect leading to worse outcomes among already insured patients, such as vulnerable Medicare patients. Using Medicare data from 2004 to 2009, we examined trends in preventable hospitalizations for conditions such as uncontrolled hypertension and diabetes--markers of access to effective primary care--in Massachusetts compared to control states. We found that after Massachusettss health reform, preventable hospitalization rates for Medicare patients actually decreased more in Massachusetts than in control states (a reduction of 101 admissions per 100,000 patients per quarter compared to a reduction of 83 admissions). Therefore, we found no evidence that Massachusettss insurance expansion had a deleterious spillover effect on preventable hospitalizations among the previously insured. Our findings should offer some reassurance that it is possible to expand access to uninsured Americans without negatively affecting important clinical outcomes for those who are already insured.
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Contributions of syntactic awareness to reading in Chinese-speaking adolescent readers with and without dyslexia.
Dyslexia
PUBLISHED: 01-23-2013
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This study investigated the relative contribution of syntactic awareness to Chinese reading among Chinese-speaking adolescent readers with and without dyslexia. A total of 78 junior high school students in Hong Kong, 26 dyslexic adolescent readers, 26 average adolescent readers of the same age (chronological age control group) and 26 younger readers matched with the same reading level (reading-level group) participated and were administered measures of IQ, syntactic awareness, morphological awareness, vocabulary knowledge, working memory, word reading, and reading comprehension. Results showed that dyslexic readers scored significantly lower than chronological age but similarly to reading level control groups in most measures, especially in the areas of syntactic skills. Analyses of individual data also revealed that over half of the dyslexic readers exhibited certain aspects of deficits in syntactic skills. In regression analyses, syntactic skills were the strongest predictors of ability in word reading and reading comprehension measures. This study highlights the uniquely important correlates of syntactic skills in Chinese reading acquisition and impairment.
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FOXM1b, which is present at elevated levels in cancer cells, has a greater transforming potential than FOXM1c.
Front Oncol
PUBLISHED: 01-11-2013
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The forkhead box (FOX) M1 transcription factor is required to maintain the proliferation of cancer cells. Two transcriptionally active isoforms of FOXM1, FOXM1b and FOXM1c, have been identified, but their functional differences remain unclear. FOXM1c is distinguished from FOXM1b by an extra exon (exon Va) that contains an ERK1/2 target sequence. Based on a literature search and quantitative PCR analysis, we concluded that FOXM1b is the predominant isoform that is overexpressed in cancers. The further characterization of FOXM1b and FOXM1c revealed two interesting differences. First, FOXM1b exhibited a higher transforming ability than FOXM1c in a soft agar assay. Second, the transactivating activity of FOXM1c, but not that of FOXM1b, was sensitive to activation by RAF/MEK/MAPK signaling. Importantly, the MEK1 activation of FOXM1c was associated with proteolytic processing to generate short forms that might represent constitutively active forms missing the N-terminal inhibitory domain; in contrast, the proteolytic processing of FOXM1b did not require MEK1 activation. Our findings suggest that FOXM1b is functionally more active. These results provide novel insights into the regulation of FOXM1 activity and its role in tumorigenesis.
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AMPK activators suppress cervical cancer cell growth through inhibition of DVL3 mediated Wnt/?-catenin signaling activity.
PLoS ONE
PUBLISHED: 01-02-2013
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Recent evidence has suggested that AMPK activators may be applied as therapeutic drugs in suppressing cancer cell growth. However, the molecular mechanism of their suppressive function in cancer cells is still unclear. Here we show that AMPK activators impair cervical cancer cell growth through the reduction of DVL3, a positive regulator in Wnt/?-catenin signaling and an oncogenic player in cervical cancer tumorigenesis. By western blot and immunohistochemical analyses, we demonstrated that DVL3 was frequently upregulated and significantly associated with elevated ?-catenin (P = 0.009) and CyclinD1 (P = 0.009) expressions in cervical cancer. Enforced expression of DVL3 elevated ?-catenin and augmented cervical cancer cell growth, verifying that DVL3-mediated Wnt/?-catenin activation is involved in cervical cancer oncogenesis. On the other aspect, we noted that the cervical cancer cell growth was remarkably suppressed by AMPK activators and such cell growth inhibition was in concomitant with the reduction of DVL3 protein level in dose- and time-dependent manners. Besides, impaired mTOR signaling activity also reduced DVL3 expression. In contrast, co-treatment with Compound C (AMPK inhibitor) could significantly abrogate metformin induced DVL3 reduction. In addition, co-treatment with AM114 or MG132 (proteosomal inhibitors) could partially restore DVL3 expression under the treatment of metformin. Further in vivo ubiquitination assay revealed that metformin could reduce DVL3 by ubiquitin/proteasomal degradation. To our knowledge, this is the first report showing the probable molecular mechanisms of that the AMPK activators suppress cervical cancer cell growth by impairing DVL3 protein synthesis via AMPK/mTOR signaling and/or partially promoting the proteasomal degradation of DVL3.
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Fis1, Mff, MiD49, and MiD51 mediate Drp1 recruitment in mitochondrial fission.
Mol. Biol. Cell
PUBLISHED: 01-02-2013
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Several mitochondrial outer membrane proteins-mitochondrial fission protein 1 (Fis1), mitochondrial fission factor (Mff), mitochondrial dynamics proteins of 49 and 51 kDa (MiD49 and MiD51, respectively)-have been proposed to promote mitochondrial fission by recruiting the GTPase dynamin-related protein 1 (Drp1), but fundamental issues remain concerning their function. A recent study supported such a role for Mff but not for Fis1. In addition, it is unclear whether MiD49 and MiD51 activate or inhibit fission, because their overexpression causes extensive mitochondrial elongation. It is also unknown whether these proteins can act in the absence of one another to mediate fission. Using Fis1-null, Mff-null, and Fis1/Mff-null cells, we show that both Fis1 and Mff have roles in mitochondrial fission. Moreover, immunofluorescence analysis of Drp1 suggests that Fis1 and Mff are important for the number and size of Drp1 puncta on mitochondria. Finally, we find that either MiD49 or MiD51 can mediate Drp1 recruitment and mitochondrial fission in the absence of Fis1 and Mff. These results demonstrate that multiple receptors can recruit Drp1 to mediate mitochondrial fission.
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Genome-wide analysis reveals coating of the mitochondrial genome by TFAM.
PLoS ONE
PUBLISHED: 01-01-2013
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Mitochondria contain a 16.6 kb circular genome encoding 13 proteins as well as mitochondrial tRNAs and rRNAs. Copies of the genome are organized into nucleoids containing both DNA and proteins, including the machinery required for mtDNA replication and transcription. The transcription factor TFAM is critical for initiation of transcription and replication of the genome, and is also thought to perform a packaging function. Although specific binding sites required for initiation of transcription have been identified in the D-loop, little is known about the characteristics of TFAM binding in its nonspecific packaging state. In addition, it is unclear whether TFAM also plays a role in the regulation of nuclear gene expression. Here we investigate these questions by using ChIP-seq to directly localize TFAM binding to DNA in human cells. Our results demonstrate that TFAM uniformly coats the whole mitochondrial genome, with no evidence of robust TFAM binding to the nuclear genome. Our study represents the first high-resolution assessment of TFAM binding on a genome-wide scale in human cells.
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How action influences object perception.
Front Psychol
PUBLISHED: 01-01-2013
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Although object perception is typically associated with the parvocellular (P) pathway, a form of fast "gist" object perception may be due to activity in the magnocellular (M) pathway (Kveraga et al., 2007). Because the M-pathway is typically associated with action, we hypothesized that manipulations of action would influence speeded object perception. In three experiments, participants indicated whether the objects shown in low and high spatial frequency (HSF) images were larger or smaller than a prototypical shoebox. In Experiment 1, participants used a proximal (hands on monitor) or distal (hands on keyboard) hand posture in separate blocks. In Experiment 2, only the proximal hand posture was used, but the hands were either action oriented with palms in (palms toward the stimuli) or non-action oriented with palms out (palms away from the stimuli). In Experiment 3, we used the palms-in proximal hand posture but manipulated the type of visual stimuli such that they were either action oriented (easily grasped) or non-action oriented (not easily grasped). In all three experiments, the advantage in identifying the low spatial frequency (LSF) images was greater when action was primed (proximal hands, palms-in, graspable). Together, these experiments show that the M-pathway is involved in rapid "gist" object perception, and this type of object perception is influenced by action.
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Carotid body tumours.
Br J Hosp Med (Lond)
PUBLISHED: 11-02-2011
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Carotid body tumours are a rare class of paraganglionoma arising from the upper neck, but should be considered in the differential diagnosis of neck lumps. A wrong diagnosis of cervical lymphadenopathy followed by excision biopsy may have serious consequences. The only way to minimize such risk is to be aware of their existence.
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Shared electronic vascular risk decision support in primary care: Computerization of Medical Practices for the Enhancement of Therapeutic Effectiveness (COMPETE III) randomized trial.
Arch. Intern. Med.
PUBLISHED: 10-26-2011
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Computerized decision support systems (CDSSs) linked with electronic medical records (EMRs) are promoted as an effective means of improving patient care. However, very few high-quality studies are set in routine, community-based clinical care, and no consistent evidence of an effect on patient outcomes has been found.
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Defining the nature of human pluripotent stem cell progeny.
Cell Res.
PUBLISHED: 08-16-2011
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While it is clear that human pluripotent stem cells (hPSCs) can differentiate to generate a panoply of various cell types, it is unknown how closely in vitro development mirrors that which occurs in vivo. To determine whether human embryonic stem cells (hESCs) and human-induced pluripotent stem cells (hiPSCs) make equivalent progeny, and whether either makes cells that are analogous to tissue-derived cells, we performed comprehensive transcriptome profiling of purified PSC derivatives and their tissue-derived counterparts. Expression profiling demonstrated that hESCs and hiPSCs make nearly identical progeny for the neural, hepatic, and mesenchymal lineages, and an absence of re-expression from exogenous reprogramming factors in hiPSC progeny. However, when compared to a tissue-derived counterpart, the progeny of both hESCs and hiPSCs maintained expression of a subset of genes normally associated with early mammalian development, regardless of the type of cell generated. While pluripotent genes (OCT4, SOX2, REX1, and NANOG) appeared to be silenced immediately upon differentiation from hPSCs, genes normally unique to early embryos (LIN28A, LIN28B, DPPA4, and others) were not fully silenced in hPSC derivatives. These data and evidence from expression patterns in early human fetal tissue (3-16 weeks of development) suggest that the differentiated progeny of hPSCs are reflective of very early human development (< 6 weeks). These findings provide support for the idea that hPSCs can serve as useful in vitro models of early human development, but also raise important issues for disease modeling and the clinical application of hPSC derivatives.
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Education in long-term care for family medicine residents: description of an integrated program.
Can Fam Physician
PUBLISHED: 08-16-2011
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Family medicine residents require more exposure to all aspects of care of the elderly in the community, including care in long-term care (LTC) homes.
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Aberrant activation of ERK/FOXM1 signaling cascade triggers the cell migration/invasion in ovarian cancer cells.
PLoS ONE
PUBLISHED: 07-26-2011
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Forkhead box M1 (FOXM1) is a proliferation-associated transcription factor essential for cell cycle progression. Numerous studies have documented that FOXM1 has multiple functions in tumorigenesis and its elevated levels are frequently associated with cancer progression. Here, we characterized the role of ERK/FOXM1 signaling in mediating the metastatic potential of ovarian cancer cells. Immunohistochemical (IHC), immunoblotting and semi-quantitative RT-PCR analyses found that both phospho-ERK and FOXM1 were frequently upregulated in ovarian cancers. Intriguingly, the overexpressed phospho-ERK (p<0.001) and FOXM1 (p<0.001) were significantly correlated to high-grade ovarian tumors with aggressive behavior such as metastasized lymph node (5 out of 6). Moreover, the expressions of phospho-ERK and FOXM1 had significantly positive correlation (p<0.001). Functionally, ectopic expression of FOXM1B remarkably enhanced cell migration/invasion, while FOXM1C not only increased cell proliferation but also promoted cell migration/invasion. Conversely, inhibition of FOXM1 expression by either thiostrepton or U0126 could significantly impair FOXM1 mediated oncogenic capacities. However, the down-regulation of FOXM1 by either thiostrepton or U0126 required the presence of p53 in ovarian cancer cells. Collectively, our data suggest that over-expression of FOXM1 might stem from the constitutively active ERK which confers the metastatic capabilities to ovarian cancer cells. The impairment of metastatic potential of cancer cells by FOXM1 inhibitors underscores its therapeutic value in advanced ovarian tumors.
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Parkin uses the UPS to ship off dysfunctional mitochondria.
Autophagy
PUBLISHED: 07-01-2011
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Parkin is a ubiquitin E3 ligase that is implicated in familial Parkinson disease (PD). Previous studies have established its role in mitophagy, a pathway whereby dysfunctional mitochondria are targeted for autophagic degradation. We recently reported that a major function of Parkin in dysfunctional mitochondria is to activate the ubiquitin-proteasome system (UPS) for proteolysis of multiple outer membrane proteins, and that such activation of the UPS is a critical step in Parkin-mediated mitophagy. Here, we discuss the possible roles of the UPS in mitophagy and the pathogenesis of PD.
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The mitochondrial transcription and packaging factor Tfam imposes a U-turn on mitochondrial DNA.
Nat. Struct. Mol. Biol.
PUBLISHED: 06-20-2011
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Tfam (transcription factor A, mitochondrial), a DNA-binding protein with tandem high-mobility group (HMG)-box domains, has a central role in the expression, maintenance and organization of the mitochondrial genome. It activates transcription from mitochondrial promoters and organizes the mitochondrial genome into nucleoids. Using X-ray crystallography, we show that human Tfam forces promoter DNA to undergo a U-turn, reversing the direction of the DNA helix. Each HMG-box domain wedges into the DNA minor groove to generate two kinks on one face of the DNA. On the opposite face, a positively charged ?-helix serves as a platform to facilitate DNA bending. The structural principles underlying DNA bending converge with those of the unrelated HU family proteins, which have analogous architectural roles in organizing bacterial nucleoids. The functional importance of this extreme DNA bending is promoter specific and seems to be related to the orientation of Tfam on the promoters.
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Functional human artificial chromosomes are generated and stably maintained in human embryonic stem cells.
Hum. Mol. Genet.
PUBLISHED: 05-18-2011
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We present a novel and efficient non-integrating gene expression system in human embryonic stem cells (hESc) utilizing human artificial chromosomes (HAC), which behave as autonomous endogenous host chromosomes and segregate correctly during cell division. HAC are important vectors for investigating the organization and structure of the kinetochore, and gene complementation. HAC have so far been obtained in immortalized or tumour-derived cell lines, but never in stem cells, thus limiting their potential therapeutic application. In this work, we modified the herpes simplex virus type 1 amplicon system for efficient transfer of HAC DNA into two hESc. The deriving stable clones generated green fluorescent protein gene-expressing HAC at high frequency, which were stably maintained without selection for 3 months. Importantly, no integration of the HAC DNA was observed in the hESc lines, compared with the fibrosarcoma-derived control cells, where the exogenous DNA frequently integrated in the host genome. The hESc retained pluripotency, differentiation and teratoma formation capabilities. This is the first report of successfully generating gene expressing de novo HAC in hESc, and is a significant step towards the genetic manipulation of stem cells and potential therapeutic applications.
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A very unusual presentation of metastatic colon cancer.
ISRN Oncol
PUBLISHED: 03-20-2011
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This case highlights two very rare complications of metastatic colorectal carcinoma. It describes a 59 year old female with both cutaneous and endometrial metastases from colorectal carcinoma. While both of these presentations are very unusual, they highlight the need to be vigilant about the detection of metastatic complications during follow up.
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piRNAs meet mitochondria.
Dev. Cell
PUBLISHED: 03-15-2011
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zuc/MitoPLD encodes a conserved enzyme that localizes to mitochondria and hydrolyzes the mitochondria-specific lipid cardiolipin. Surprisingly, zuc/MitoPLD activity is required for Piwi-interacting RNA (piRNA)-mediated silencing of transposable elements in fly and mouse germlines, suggesting that signaling from mitochondria influences the piRNA pathway.
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Zic2 synergistically enhances Hedgehog signalling through nuclear retention of Gli1 in cervical cancer cells.
J. Pathol.
PUBLISHED: 03-11-2011
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Aberrant activation of Hedgehog (Hh) signalling has been implicated in the pathogenesis of human cancers. However, the cognate molecular mechanisms contributing to this disregulated pathway are incompletely understood. In this study, we showed that Zic2 was frequently over-expressed and associated with high-grade cervical cancer (p = 0.032), high levels of Gli1 (p < 0.001) and CyclinD1 (p < 0.001) by immunohistochemical and quantitative RT-PCR analyses. Further biochemical studies using luciferase reporter, co-immunoprecipitation, subcellular fractionation and immunofluorescence analyses demonstrated that Zic2 can physically interact with Gli1 and retain it in the nucleus, which in turn increases Gli-mediated transcriptional activity. Gain- and loss-of-function analyses of Zic2 showed that Zic2 could increase Hh signalling activity, cell proliferation and anchorage-independent growth ability in cervical cancer cells. Conversely, deletion of the zinc finger domain at C-terminus of Zic2 significantly abrogated its interaction with Gli1, the retention of Gli1 in the nucleus, effects on Hh signalling activity and oncogenic properties in cervical cancer cells. Our findings suggest that Zic2 is a positive modulator increasing Gli1 transcriptional and oncogenic activity by retaining Gli1 in the nucleus of cervical cancer cells.
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Exploring platelet chemokine antimicrobial activity: nuclear magnetic resonance backbone dynamics of NAP-2 and TC-1.
Antimicrob. Agents Chemother.
PUBLISHED: 02-14-2011
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The platelet chemokines neutrophil-activating peptide-2 (NAP-2) and thrombocidin-1 (TC-1) differ by only two amino acids at their carboxy-terminal ends. Nevertheless, they display a significant difference in their direct antimicrobial activities, with the longer NAP-2 being inactive and TC-1 being active. In an attempt to rationalize this difference in activity, we studied the structure and the dynamics of both proteins by nuclear magnetic resonance (NMR) spectroscopy. Using 15N isotope-labeled protein, we confirmed that the two monomeric proteins essentially have the same overall structure in aqueous solution. However, NMR relaxation measurements provided evidence that the negatively charged carboxy-terminal residues of NAP-2 experience a restricted motion, whereas the carboxy-terminal end of TC-1 moves in an unrestricted manner. The same behavior was also seen in molecular dynamic simulations of both proteins. Detailed analysis of the protein motions through model-free analysis, as well as a determination of their overall correlation times, provided evidence for the existence of a monomer-dimer equilibrium in solution, which seemed to be more prevalent for TC-1. This finding was supported by diffusion NMR experiments. Dimerization generates a larger cationic surface area that would increase the antimicrobial activities of these chemokines. Moreover, these data also show that the negatively charged carboxy-terminal end of NAP-2 (which is absent in TC-1) folds back over part of the positively charged helical region of the protein and, in doing so, interferes with the direct antimicrobial activity.
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Broad activation of the ubiquitin-proteasome system by Parkin is critical for mitophagy.
Hum. Mol. Genet.
PUBLISHED: 02-04-2011
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Parkin, an E3 ubiquitin ligase implicated in Parkinsons disease, promotes degradation of dysfunctional mitochondria by autophagy. Using proteomic and cellular approaches, we show that upon translocation to mitochondria, Parkin activates the ubiquitin-proteasome system (UPS) for widespread degradation of outer membrane proteins. This is evidenced by an increase in K48-linked polyubiquitin on mitochondria, recruitment of the 26S proteasome and rapid degradation of multiple outer membrane proteins. The degradation of proteins by the UPS occurs independently of the autophagy pathway, and inhibition of the 26S proteasome completely abrogates Parkin-mediated mitophagy in HeLa, SH-SY5Y and mouse cells. Although the mitofusins Mfn1 and Mfn2 are rapid degradation targets of Parkin, we find that degradation of additional targets is essential for mitophagy. These results indicate that remodeling of the mitochondrial outer membrane proteome is important for mitophagy, and reveal a causal link between the UPS and autophagy, the major pathways for degradation of intracellular substrates.
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A mathematical model for antimalarial drug resistance.
Math Med Biol
PUBLISHED: 09-30-2010
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We formulate and analyze a mathematical model for malaria with treatment and the well-known three levels of resistance in humans. The model incorporates both sensitive and resistant strains of the parasites. Analytical results reveal that the model exhibits the phenomenon of backward bifurcation (co-existence of a stable disease-free equilibrium with a stable endemic equilibrium), an epidemiological situation where although necessary, having the basic reproduction number less than unity, it is not sufficient for disease elimination. Through quantitative analysis, we show the effects of varying treatment levels in a high transmission area with different levels of resistance. Increasing treatment has limited benefits in a population with resistant strains, especially in high transmission settings. Thus, in a cost-benefit analysis, the rate of treatment and percentage to be treated become difficult questions to address.
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Game-based versus traditional case-based learning: comparing effectiveness in stroke continuing medical education.
Can Fam Physician
PUBLISHED: 09-16-2010
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To evaluate family physicians enjoyment of and knowledge gained from game-based learning, compared with traditional case-based learning, in a continuing medical education (CME) event on stroke prevention and management.
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A phase II trial of docetaxel with bevacizumab as first-line therapy for HER2-negative metastatic breast cancer (TORI B01).
Clin. Breast Cancer
PUBLISHED: 08-14-2010
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Addition of the antiangiogenic agent bevacizumab to paclitaxel significantly improves response rates and progression-free survival for metastatic breast cancer (MBC). To assess the activity of docetaxel plus bevacizumab, a multicenter phase II trial was conducted.
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Current understanding of fatty acid biosynthesis and the acyl carrier protein.
Biochem. J.
PUBLISHED: 07-29-2010
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FA (fatty acid) synthesis represents a central, conserved process by which acyl chains are produced for utilization in a number of end-products such as biological membranes. Central to FA synthesis, the ACP (acyl carrier protein) represents the cofactor protein that covalently binds all fatty acyl intermediates via a phosphopantetheine linker during the synthesis process. FASs (FA synthases) can be divided into two classes, type I and II, which are primarily present in eukaryotes and bacteria/plants respectively. They are characterized by being composed of either large multifunctional polypeptides in the case of type I or consisting of discretely expressed mono-functional proteins in the type II system. Owing to this difference in architecture, the FAS system has been thought to be a good target for the discovery of novel antibacterial agents, as exemplified by the antituberculosis drug isoniazid. There have been considerable advances in this field in recent years, including the first high-resolution structural insights into the type I mega-synthases and their dynamic behaviour. Furthermore, the structural and dynamic properties of an increasing number of acyl-ACPs have been described, leading to an improved comprehension of this central carrier protein. In the present review we discuss the state of the understanding of FA synthesis with a focus on ACP. In particular, developments made over the past few years are highlighted.
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Physiological functions of mitochondrial fusion.
Ann. N. Y. Acad. Sci.
PUBLISHED: 07-24-2010
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In recent years, the dynamic nature of mitochondria has been discovered to be critical for their function. Here we discuss the molecular basis of mitochondrial fusion, its protective role in neurodegeneration, and its importance in cellular function. The mitofusins Mfn1 and Mfn2, GTPases localized to the outer membrane, mediate outer-membrane fusion. OPA1, a GTPase associated with the inner membrane, mediates subsequent inner-membrane fusion. Mutations in Mfn2 or OPA1 cause neurodegenerative diseases. Mouse models with defects in mitochondrial fusion genes have provided important avenues for understanding how fusion maintains mitochondrial physiology and neuronal function. Mitochondrial fusion enables content mixing within a mitochondrial population, thereby preventing permanent loss of essential components. Cells with reduced mitochondrial fusion, as a consequence, show a subpopulation of mitochondria that lack mtDNA nucleoids. Such mtDNA defects lead to respiration-deficient mitochondria, and their accumulation in neurons leads to impaired outgrowth of cellular processes and ultimately neurodegeneration.
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NMR solution structure and biophysical characterization of Vibrio harveyi acyl carrier protein A75H: effects of divalent metal ions.
J. Biol. Chem.
PUBLISHED: 07-21-2010
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Bacterial acyl carrier protein (ACP) is a highly anionic, 9 kDa protein that functions as a cofactor protein in fatty acid biosynthesis. Escherichia coli ACP is folded at neutral pH and in the absence of divalent cations, while Vibrio harveyi ACP, which is very similar at 86% sequence identity, is unfolded under the same conditions. V. harveyi ACP adopts a folded conformation upon the addition of divalent cations such as Ca(2+) and Mg(2+) and a mutant, A75H, was previously identified that restores the folded conformation at pH 7 in the absence of divalent cations. In this study we sought to understand the unique folding behavior of V. harveyi ACP using NMR spectroscopy and biophysical methods. The NMR solution structure of V. harveyi ACP A75H displays the canonical ACP structure with four helices surrounding a hydrophobic core, with a narrow pocket closed off from the solvent to house the acyl chain. His-75, which is charged at neutral pH, participates in a stacking interaction with Tyr-71 in the far C-terminal end of helix IV. pH titrations and the electrostatic profile of ACP suggest that V. harveyi ACP is destabilized by anionic charge repulsion around helix II that can be partially neutralized by His-75 and is further reduced by divalent cation binding. This is supported by differential scanning calorimetry data which indicate that calcium binding further increases the melting temperature of V. harveyi ACP A75H by ?20 °C. Divalent cation binding does not alter ACP dynamics on the ps-ns timescale as determined by (15)N NMR relaxation experiments, however, it clearly stabilizes the protein fold as observed by hydrogen-deuterium exchange studies. Finally, we demonstrate that the E. coli ACP H75A mutant is similarly unfolded as wild-type V. harveyi ACP, further stressing the importance of this particular residue for proper protein folding.
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Laparoscopic drainage of retroperitoneal abscess secondary to pyogenic sacroiliitis.
Ann R Coll Surg Engl
PUBLISHED: 05-27-2010
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Retroperitoneal abscesses are rare complications of pyogenic sacroiliitis. Diagnosis is often delayed due to the initial non-specific symptoms and signs and also a low awareness of the clinical presentation and diagnostic procedures among clinicians. We describe a case of an 18-year-old man who was diagnosed with septic arthritis of his left sacro-iliac joint which was complicated by a retroperitoneal abscess. After discussion with the radiologist and orthopaedic surgeons, the abscess was successfully drained via minimally invasive surgery transperitoneally.
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Differential functions of growth factor receptor-bound protein 7 (GRB7) and its variant GRB7v in ovarian carcinogenesis.
Clin. Cancer Res.
PUBLISHED: 04-13-2010
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Aberrant overexpression of growth factor receptor-bound protein 7 (GRB7) and its variant GRB7v has been found in numerous human cancers. The goal of this study was to characterize the functions of GRB7 and GRB7v in the ovarian carcinogenesis and to investigate the differential roles of GRB7 and GRB7v in the modulation of signaling pathways.
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Cognitive skills and literacy performance of Chinese adolescents with and without dyslexia.
Read Writ
PUBLISHED: 04-02-2010
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The present study sought to identify cognitive abilities that might distinguish Hong Kong Chinese adolescents with dyslexia and to assess how these abilities were associated with Chinese word reading, word dictation, and reading comprehension. The cognitive skills of interest were morphological awareness, visual-orthographic knowledge, rapid naming, and verbal working memory. A total of 90 junior secondary school students, 30 dyslexic, 30 chronological age controls, and 30 reading level controls was tested on a range of cognitive and literacy tasks. Dyslexic students were less competent than the control students in all cognitive and literacy measures. The regression analyses also showed that verbal working memory, rapid naming, morphological awareness, and visual-orthographic knowledge were significantly associated with literacy performance. Findings underscore the importance of these cognitive skills for Chinese literacy acquisition. Overall, this study highlights the persistent difficulties of Chinese dyslexic adolescents who seem to have multiple causes for reading and spelling difficulties.
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Contribution of discourse and morphosyntax skills to reading comprehension in Chinese dyslexic and typically developing children.
Ann Dyslexia
PUBLISHED: 03-01-2010
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This study aimed at identifying important skills for reading comprehension in Chinese dyslexic children and their typically developing counterparts matched on age (CA controls) or reading level (RL controls). The children were assessed on Chinese reading comprehension, cognitive, and reading-related skills. Results showed that the dyslexic children performed significantly less well than the CA controls but similarly to RL controls in most measures. Results of multiple regression analyses showed that word-level reading-related skills like oral vocabulary and word semantics were found to be strong predictors of reading comprehension among typically developing junior graders and dyslexic readers of senior grades, whereas morphosyntax, a text-level skill, was most predictive for typically developing senior graders. It was concluded that discourse and morphosyntax skills are particularly important for reading comprehension in the non-inflectional and topic-prominent Chinese system.
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Molecular dynamics simulations of beta-ketoacyl-, beta-hydroxyacyl-, and trans-2-enoyl-acyl carrier proteins of Escherichia coli.
Biochemistry
PUBLISHED: 02-26-2010
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Acyl carrier protein (ACP) is the central player in fatty acid (FA) biosynthesis. It covalently binds all FA intermediates and presents them to the enzymes needed for elongation. Bacterial ACP must interact with a large number of proteins, which raises the question of how different acyl-ACPs are recognized and distinguished from each other. We performed molecular dynamics (MD) simulations of the FA synthase intermediates beta-ketoacyl-, beta-hydroxyacyl, and trans-2-enoyl-ACP spanning from 4 to 18 carbon groups in length. These forms of acyl-ACP have largely yet to be characterized experimentally, and our simulations provide a first insight into these structures. The simulations were conducted with the acyl chain directed into the solvent, as well as in a solvent-protected conformation inside the hydrophobic pocket of Escherichia coli ACP. Spontaneous migration from the solvent-exposed state into the hydrophobic binding pocket of ACP was seen in each of the intermediate classes studied, but not in all the individual simulations. This confirms that the intermediates can enter and utilize the same hydrophobic pockets as saturated acyl chains. In addition, a recurring, novel association of the acyl chains with loop I of ACP was observed that may be occupied transiently before entry into the hydrophobic pocket. The MD simulations of the acyl chains in a solvent-shielded state reveal that the polar functional group in the beta position of the beta-ketoacyl and beta-hydroxyacyl chains anchors these moieties at the cavity entrance, while the chains without a polar group in the beta position lack this additional anchoring atom. This leads to a binding mode in which the beta-ketoacyl and beta-hydroxyacyl chains are positioned further from the bottom of the pocket compared to the saturated and enoyl chains, particularly in short chain (
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OPA1 disease alleles causing dominant optic atrophy have defects in cardiolipin-stimulated GTP hydrolysis and membrane tubulation.
Hum. Mol. Genet.
PUBLISHED: 02-25-2010
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The dynamin-related GTPase OPA1 is mutated in autosomal dominant optic atrophy (DOA) (Kjer type), an inherited neuropathy of the retinal ganglion cells. OPA1 is essential for the fusion of the inner mitochondrial membranes, but its mechanism of action remains poorly understood. Here we show that OPA1 has a low basal rate of GTP hydrolysis that is dramatically enhanced by association with liposomes containing negative phospholipids such as cardiolipin. Lipid association triggers assembly of OPA1 into higher order oligomers. In addition, we find that OPA1 can promote the protrusion of lipid tubules from the surface of cardiolipin-containing liposomes. In such lipid protrusions, OPA1 assemblies are observed on the outside of the lipid tubule surface, a protein-membrane topology similar to that of classical dynamins. The membrane tubulation activity of OPA1 is suppressed by GTPgammaS. OPA1 disease alleles associated with DOA display selective defects in several activities, including cardiolipin association, GTP hydrolysis and membrane tubulation. These findings indicate that interaction of OPA1 with membranes can stimulate higher order assembly, enhance GTP hydrolysis and lead to membrane deformation into tubules.
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Mitochondrial fusion is required for mtDNA stability in skeletal muscle and tolerance of mtDNA mutations.
Cell
PUBLISHED: 02-09-2010
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Mitochondria are highly mobile and dynamic organelles that continually fuse and divide. These processes allow mitochondria to exchange contents, including mitochondrial DNA (mtDNA). Here we examine the functions of mitochondrial fusion in differentiated skeletal muscle through conditional deletion of the mitofusins Mfn1 and Mfn2, mitochondrial GTPases essential for fusion. Loss of the mitofusins causes severe mitochondrial dysfunction, compensatory mitochondrial proliferation, and muscle atrophy. Mutant mice have severe mtDNA depletion in muscle that precedes physiological abnormalities. Moreover, the mitochondrial genomes of the mutant muscle rapidly accumulate point mutations and deletions. In a related experiment, we find that disruption of mitochondrial fusion strongly increases mitochondrial dysfunction and lethality in a mouse model with high levels of mtDNA mutations. With its dual function in safeguarding mtDNA integrity and preserving mtDNA function in the face of mutations, mitochondrial fusion is likely to be a protective factor in human disorders associated with mtDNA mutations.
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Rate of inducible ventricular arrhythmia in adults with congenital heart disease.
Am. J. Cardiol.
PUBLISHED: 01-25-2010
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Patients with adult congenital heart disease are at increased risk of ventricular arrhythmia (VA) and sudden cardiac death, although no clear predictors have been found. Ventricular programmed stimulation has been shown to predict clinical ventricular tachycardia and sudden death events, but the role of screening electrophysiology studies (S-EPSs) in this population remains poorly defined. Therefore, we sought to determine the prevalence of inducible VA and to evaluate the clinical predictors in a heterogeneous group of patients with adult congenital heart disease (> or =18 years old) undergoing S-EPSs at preoperative or interventional cardiac catheterization. Studies for the primary evaluation of clinical VA were excluded. The demographic, clinical, and diagnostic findings were compared between the patients with positive and negative findings. From 2005 to 2009, 80 patients (mean age 30 +/- 9 years) underwent S-EPSs, and 23 had inducible VA. The diagnoses for those with studies positive for VA included tetralogy of Fallot (n = 12), d-transposition of the great arteries (n = 6), pulmonary stenosis (n = 2), double outlet right ventricle (n = 1), double inlet left ventricle (n = 1), and Ebsteins anomaly (n = 1). Men were significantly more likely to have a S-EPS positive for VA (p = 0.015). Increasing QRS duration, decreasing peak oxygen uptake (percentage of predicted), and ventricular fibrosis with cardiovascular magnetic resonance imaging were significantly associated with studies positive for VA (p <0.05). Combined fibrosis and a peak oxygen uptake <80% of predicted had 100% sensitivity for positive VA findings. In conclusion, almost 30% of those with adult congenital heart disease undergoing S-EPSs had inducible VA. A prolonged QRS duration, diminished exercise capacity, and the presence of ventricular fibrosis were significantly associated with findings positive for VA and might improve patient selection for screening evaluations.
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Urinary incontinence should be added to the manifestation in women with Marfan syndrome.
Int Urogynecol J
PUBLISHED: 01-12-2010
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We aimed to compare the incidence of urinary incontinence in women with Marfan syndrome and controls, hypothesizing that connective tissue abnormality could contribute to urinary incontinence.
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An in silico approach to the analysis of acute wound healing.
Wound Repair Regen
PUBLISHED: 12-11-2009
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The complex interactions that characterize acute wound healing have stymied the development of effective therapeutic modalities. The use of computational models holds the promise to improve our basic approach to understanding the process. By modifying an existing ordinary differential equation model of systemic inflammation to simulate local wound healing, we expect to improve the understanding of the underlying complexities of wound healing and thus allow for the development of novel, targeted therapeutic strategies. The modifications in this local acute wound healing model include: evolution from a systemic model to a local model, the incorporation of fibroblast activity, and the effects of tissue oxygenation. Using these modifications we are able to simulate impaired wound healing in hypoxic wounds with varying levels of contamination. Possible therapeutic targets, such as fibroblast death rate and rate of fibroblast recruitment, have been identified by computational analysis. This model is a step toward constructing an integrative systems biology model of human wound healing.
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Tissue doppler changes in pediatric complete heart block patients who are chronically paced.
Congenit Heart Dis
PUBLISHED: 11-21-2009
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Pediatric patients with complete heart block (CHB) often require pacemaker therapy. Adult studies have shown chronic right ventricular pacemaker therapy may be associated with decreased echocardiographic parameters and increased brain natriuretic peptide (BNP) values. The goal of this study was to determine if there are echocardiographic or BNP changes in a pediatric population that is chronically paced.
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Mitochondrial dynamics--fusion, fission, movement, and mitophagy--in neurodegenerative diseases.
Hum. Mol. Genet.
PUBLISHED: 10-08-2009
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Neurons are metabolically active cells with high energy demands at locations distant from the cell body. As a result, these cells are particularly dependent on mitochondrial function, as reflected by the observation that diseases of mitochondrial dysfunction often have a neurodegenerative component. Recent discoveries have highlighted that neurons are reliant particularly on the dynamic properties of mitochondria. Mitochondria are dynamic organelles by several criteria. They engage in repeated cycles of fusion and fission, which serve to intermix the lipids and contents of a population of mitochondria. In addition, mitochondria are actively recruited to subcellular sites, such as the axonal and dendritic processes of neurons. Finally, the quality of a mitochondrial population is maintained through mitophagy, a form of autophagy in which defective mitochondria are selectively degraded. We review the general features of mitochondrial dynamics, incorporating recent findings on mitochondrial fusion, fission, transport and mitophagy. Defects in these key features are associated with neurodegenerative disease. Charcot-Marie-Tooth type 2A, a peripheral neuropathy, and dominant optic atrophy, an inherited optic neuropathy, result from a primary deficiency of mitochondrial fusion. Moreover, several major neurodegenerative diseases--including Parkinsons, Alzheimers and Huntingtons disease--involve disruption of mitochondrial dynamics. Remarkably, in several disease models, the manipulation of mitochondrial fusion or fission can partially rescue disease phenotypes. We review how mitochondrial dynamics is altered in these neurodegenerative diseases and discuss the reciprocal interactions between mitochondrial fusion, fission, transport and mitophagy.
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Improving safety and eliminating redundant tests: cutting costs in U.S. hospitals.
Health Aff (Millwood)
PUBLISHED: 09-10-2009
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High costs and unsafe care are major challenges for U.S. hospitals. Two sources of raised costs and unsafe care are adverse events in hospitals and tests ordered by several different physicians. After reviewing rates of these two occurrences in U.S. hospitals and simulating their costs, we estimated that in 2004 alone, eliminating readily preventable adverse events would have resulted in direct savings of more than $16.6 billion (5.5 percent of total inpatient costs). Eliminating redundant tests would have saved an additional $8 billion (2.7 percent). Addressing these situations could generate major savings to the system while improving patient care.
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Structure-function studies of chemokine-derived carboxy-terminal antimicrobial peptides.
Biochim. Biophys. Acta
PUBLISHED: 08-20-2009
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Recent reports which show that several chemokines can act as direct microbicidal agents have drawn renewed attention to these chemotactic signalling proteins. Here we present a structure-function analysis of peptides derived from the human chemokines macrophage inflammatory protein-3alpha (MIP-3alpha/CCL20), interleukin-8 (IL-8), neutrophil activating protein-2 (NAP-2) and thrombocidin-1 (TC-1). These peptides encompass the C-terminal alpha-helices of these chemokines, which have been suggested to be important for the direct antimicrobial activities. Far-UV CD spectroscopy showed that the peptides are unstructured in aqueous solution and that a membrane mimetic solvent is required to induce a helical secondary structure. A co-solvent mixture was used to determine solution structures of the peptides by two-dimensional (1)H-NMR spectroscopy. The highly cationic peptide, MIP-3alpha(51-70), had the most pronounced antimicrobial activity and displayed an amphipathic structure. A shorter version of this peptide, MIP-3alpha(59-70), remained antimicrobial but its structure and mechanism of action were unlike that of the former peptide. The NAP-2 and TC-1 proteins differ in their sequences only by the deletion of two C-terminal residues in TC-1, but intact TC-1 is a very potent antimicrobial while NAP-2 is inactive. The corresponding C-terminal peptides, NAP-2(50-70) and TC-1(50-68), had very limited and no bactericidal activity, respectively. This suggests that other regions of TC-1 contribute to its bactericidal activity. Altogether, this work provides a rational structural basis for the biological activities of these peptides and proteins and highlights the importance of experimental characterization of peptide fragments as distinct entities because their activities and structural properties may differ substantially from their parent proteins.
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The assessment of prognosis of surgically resected oesophageal cancer is dependent on the number of lymph nodes examined pathologically.
Histopathology
PUBLISHED: 07-21-2009
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The prognosis in surgically resected oesophageal carcinoma (OC) is dependent on the number of regional lymph nodes (LN) involved, but no guidance exists on how many LNs should be examined histopathologically to give a reliable pN status. The aim of this study was to determine whether the number of LNs examined after OC resection has a significant effect on the assessment of prognosis.
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In vitro bioactivity and biocompatibility of dicalcium silicate cements for endodontic use.
J Endod
PUBLISHED: 06-10-2009
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The purpose of this study was to examine the in vitro bioactivity and biocompatibility of sol-gel-derived dicalcium silicate cements.
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What is Visualize?

JoVE Visualize is a tool created to match the last 5 years of PubMed publications to methods in JoVE's video library.

How does it work?

We use abstracts found on PubMed and match them to JoVE videos to create a list of 10 to 30 related methods videos.

Video X seems to be unrelated to Abstract Y...

In developing our video relationships, we compare around 5 million PubMed articles to our library of over 4,500 methods videos. In some cases the language used in the PubMed abstracts makes matching that content to a JoVE video difficult. In other cases, there happens not to be any content in our video library that is relevant to the topic of a given abstract. In these cases, our algorithms are trying their best to display videos with relevant content, which can sometimes result in matched videos with only a slight relation.