85 research outputs found

    The \u3ci\u3eDrosophila\u3c/i\u3e T-box Transcription Factor Midline Functions Within the Notch-Delta Signaling Pathway To Specify Sensory Organ Precursor Cell Fates and Regulates Cell Survival Within the Eye Imaginal Disc

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    We report that the T-box transcription factor Midline (Mid), an evolutionary conserved homolog of the vertebrate Tbx20 protein, functions within the Notch-Delta signaling pathway essential for specifying the fates of sensory organ precursor (SOP) cells. These findings complement an established history of research showing that Mid regulates the cell-fate specification of diverse cell types within the developing heart, epidermis and central nervous system. Tbx20 has been detected in unique neuronal and epithelial cells of embryonic eye tissues in both mice and humans. However, the mechanisms by which either Mid or Tbx20 function to regulate cell-fate specification or other critical aspects of eye development including cell survival have not yet been elucidated. We have also gathered preliminary evidence suggesting that Mid may play an indirect, but vital role in selecting SOP cells within the third-instar larval eye disc by regulating the expression of the proneural gene atonal. During subsequent pupal stages, Mid specifies SOP cell fates as a member of the Notch-Delta signaling hierarchy and is essential for maintaining cell viability by inhibiting apoptotic pathways. We present several new hypotheses that seek to understand the role of Mid in regulating developmental processes downstream of the Notch receptor that are critical for specifying unique cell fates, patterning the adult eye and maintaining cellular homeostasis during eye disc morphogenesis. Β© 2013 Elsevier Ireland Ltd

    Structural dynamics of RbmA governs plasticity of Vibrio cholerae biofilms

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    Biofilm formation is critical for the infection cycle of Vibrio cholerae. Vibrio exopolysaccharides (VPS) and the matrix proteins RbmA, Bap1 and RbmC are required for the development of biofilm architecture. We demonstrate that RbmA binds VPS directly and uses a binary structural switch within its first fibronectin type III (FnIII-1) domain to control RbmA structural dynamics and the formation of VPS-dependent higher-order structures. The structural switch in FnIII-1 regulates interactions in trans with the FnIII-2 domain, leading to open (monomeric) or closed (dimeric) interfaces. The ability of RbmA to switch between open and closed states is important for V. cholerae biofilm formation, as RbmA variants with switches that are locked in either of the two states lead to biofilms with altered architecture and structural integrity

    Swimming like algae: biomimetic soft artificial cilia

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    Cilia are used effectively in a wide variety of biological systems from fluid transport to thrust generation. Here, we present the design and implemen- tation of artificial cilia, based on a biomimetic planar actuator using soft- smart materials. This actuator is modelled on the cilia movement of the alga Volvox, and represents the cilium as a piecewise constant-curvature robotic actuator that enables the subsequent direct translation of natural articulation into a multi-segment ionic polymer metal composite actuator. It is demonstrated how the combination of optimal segmentation pattern and biologically derived per-segment driving signals reproduce natural cili- ary motion. The amenability of the artificial cilia to scaling is also demonstrated through the comparison of the Reynolds number achieved with that of natural cilia

    Establishing a clinical phenotype for cachexia in end stage kidney disease - study protocol.

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    BACKGROUND: Surveys using traditional measures of nutritional status indicate that muscle wasting is common among persons with end-stage kidney disease (ESKD). Up to 75% of adults undergoing maintenance dialysis show some evidence of muscle wasting. ESKD is associated with an increase in inflammatory cytokines and can result in cachexia, with the loss of muscle and fat stores. At present, only limited data are available on the classification of wasting experienced by persons with ESKD. Individuals with ESKD often exhibit symptoms of anorexia, loss of lean muscle mass and altered energy expenditure. These symptoms are consistent with the syndrome of cachexia observed in other chronic diseases, such as cancer, heart failure, and acquired immune deficiency syndrome. While definitions of cachexia have been developed for some diseases, such as cardiac failure and cancer, no specific cachexia definition has been established for chronic kidney disease. The importance of developing a definition of cachexia in a population with ESKD is underscored by the negative impact that symptoms of cachexia have on quality of life and the association of cachexia with a substantially increased risk of premature mortality. The aim of this study is to determine the clinical phenotype of cachexia specific to individuals with ESKD. METHODS: A longitudinal study which will recruit adult patientsΒ with ESKD receiving haemodialysis attending a Regional Nephrology Unit within the United Kingdom. Patients will be followed 2 monthly over 12Β months and measurements of weight; lean muscle mass (bioelectrical impedance, mid upper arm muscle circumference and tricep skin fold thickness); muscle strength (hand held dynamometer), fatigue, anorexia and quality of life collected. We will determine if they experience (and to what degree) the known characteristics associated with cachexia. DISCUSSION: Cachexia is a debilitating condition associated with an extremely poor outcome. Definitions of cachexia in chronic illnesses are required to reflect specific nuances associated with each disease. These discrete cachexia definitions help with the precision of research and the subsequent clinical interventions to improve outcomes for patients suffering from cachexia. The absence of a definition for cachexia in an ESKD population makes it particularly difficult to study the incidence of cachexia or potential treatments, as there are no standardised inclusion criteria for patients with ESKD who have cachexia. Outcomes from this study will provide much needed data to inform development and testing of potential treatment modalities, aimed at enhancing current clinical practice, policy and education

    High dietary diversity is associated with obesity in Sri Lankan adults: An evaluation of three dietary scores.

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    Background: Dietary diversity is recognized as a key element of a high quality diet. However, diets that offer a greater variety of energy-dense foods could increase food intake and body weight. The aim of this study was to explore association of diet diversity with obesity in Sri Lankan adults. Methods: Six hundred adults aged > 18 years were randomly selected by using multi-stage stratified sample. Dietary intake assessment was undertaken by a 24 hour dietary recall. Three dietary scores, Dietary Diversity Score (DDS), Dietary Diversity Score with Portions (DDSP) and Food Variety Score (FVS) were calculated. Body mass index (BMI) β‰₯ 25 kg.mβˆ’2 is defined as obese and Asian waist circumference cut-offs were used diagnosed abdominal obesity. Results: Mean of DDS for men and women were 6.23 and 6.50 (p=0.06), while DDSP was 3.26 and 3.17 respectively (p=0.24). FVS values were significantly different between men and women 9.55 and 10.24 (p=0.002). Dietary diversity among Sri Lankan adults was significantly associated with gender, residency, ethnicity, education level but not with diabetes status. As dietary scores increased, the percentage consumption was increased in most of food groups except starches. Obese and abdominal obese adults had the highest DDS compared to non-obese groups (p<0.05). With increased dietary diversity the level of BMI, waist circumference and energy consumption was significantly increased in this population. Conclusion: Our data suggests that dietary diversity is positively associated with several socio-demographic characteristics and obesity among Sri Lankan adults. Although high dietary diversity is widely recommended, public health messages should emphasize to improve dietary diversity in selective food items

    Early Detection of Ovarian Cancer using the Risk of Ovarian Cancer Algorithm with Frequent CA125 Testing in Women at Increased Familial Risk – Combined Results from Two Screening Trials

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    Purpose: Women at familial/genetic ovarian cancer risk often undergo screening despite unproven efficacy. Research suggests each woman has her own CA125 baseline; significant increases above this level may identify cancers earlier than standard 6- to 12-monthly CA125 > 35 U/mL. Experimental Design: Data from prospective Cancer Genetics Network and Gynecologic Oncology Group trials, which screened 3,692 women (13,080 woman-screening years) with a strong breast/ovarian cancer family history or BRCA1/2 mutations, were combined to assess a novel screening strategy. Specifically, serum CA125 q3 months, evaluated using a risk of ovarian cancer algorithm (ROCA), detected significant increases above each subject's baseline, which triggered transvaginal ultrasound. Specificity and positive predictive value (PPV) were compared with levels derived from general population screening (specificity 90%, PPV 10%), and stage-at-detection was compared with historical high-risk controls. Results: Specificity for ultrasound referral was 92% versus 90% ( P = 0.0001), and PPV was 4.6% versus 10% ( P > 0.10). Eighteen of 19 malignant ovarian neoplasms [prevalent = 4, incident = 6, risk-reducing salpingo-oophorectomy (RRSO) = 9] were detected via screening or RRSO. Among incident cases (which best reflect long-term screening performance), three of six invasive cancers were early-stage (I/II; 50% vs. 10% historical BRCA1 controls; P = 0.016). Six of nine RRSO-related cases were stage I. ROCA flagged three of six (50%) incident cases before CA125 exceeded 35 U/mL. Eight of nine patients with stages 0/I/II ovarian cancer were alive at last follow-up (median 6 years). Conclusions: For screened women at familial/genetic ovarian cancer risk, ROCA q3 months had better early-stage sensitivity at high specificity, and low yet possibly acceptable PPV compared with CA125 > 35 U/mL q6/q12 months, warranting further larger cohort evaluation. Clin Cancer Res; 23(14); 3628-37. Β©2017 AACR

    Systematic Evaluation of Candidate Blood Markers for Detecting Ovarian Cancer

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    Epithelial ovarian cancer is a significant cause of mortality both in the United States and worldwide, due largely to the high proportion of cases that present at a late stage, when survival is extremely poor. Early detection of epithelial ovarian cancer, and of the serous subtype in particular, is a promising strategy for saving lives. The low prevalence of ovarian cancer makes the development of an adequately sensitive and specific test based on blood markers very challenging. We evaluated the performance of a set of candidate blood markers and combinations of these markers in detecting serous ovarian cancer.We selected 14 candidate blood markers of serous ovarian cancer for which assays were available to measure their levels in serum or plasma, based on our analysis of global gene expression data and on literature searches. We evaluated the performance of these candidate markers individually and in combination by measuring them in overlapping sets of serum (or plasma) samples from women with clinically detectable ovarian cancer and women without ovarian cancer. Based on sensitivity at high specificity, we determined that 4 of the 14 candidate markers--MUC16, WFDC2, MSLN and MMP7--warrant further evaluation in precious serum specimens collected months to years prior to clinical diagnosis to assess their utility in early detection. We also reported differences in the performance of these candidate blood markers across histological types of epithelial ovarian cancer.By systematically analyzing the performance of candidate blood markers of ovarian cancer in distinguishing women with clinically apparent ovarian cancer from women without ovarian cancer, we identified a set of serum markers with adequate performance to warrant testing for their ability to identify ovarian cancer months to years prior to clinical diagnosis. We argued for the importance of sensitivity at high specificity and of magnitude of difference in marker levels between cases and controls as performance metrics and demonstrated the importance of stratifying analyses by histological type of ovarian cancer. Also, we discussed the limitations of studies (like this one) that use samples obtained from symptomatic women to assess potential utility in detection of disease months to years prior to clinical detection

    Repertoire of microRNAs in Epithelial Ovarian Cancer as Determined by Next Generation Sequencing of Small RNA cDNA Libraries

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    MicroRNAs (miRNAs) are small regulatory RNAs that are implicated in cancer pathogenesis and have recently shown promise as blood-based biomarkers for cancer detection. Epithelial ovarian cancer is a deadly disease for which improved outcomes could be achieved by successful early detection and enhanced understanding of molecular pathogenesis that leads to improved therapies. A critical step toward these goals is to establish a comprehensive view of miRNAs expressed in epithelial ovarian cancer tissues as well as in normal ovarian surface epithelial cells.We used massively parallel pyrosequencing (i.e., "454 sequencing") to discover and characterize novel and known miRNAs expressed in primary cultures of normal human ovarian surface epithelium (HOSE) and in tissue from three of the most common histotypes of ovarian cancer. Deep sequencing of small RNA cDNA libraries derived from normal HOSE and ovarian cancer samples yielded a total of 738,710 high-quality sequence reads, generating comprehensive digital profiles of miRNA expression. Expression profiles for 498 previously annotated miRNAs were delineated and we discovered six novel miRNAs and 39 candidate miRNAs. A set of 124 miRNAs was differentially expressed in normal versus cancer samples and 38 miRNAs were differentially expressed across histologic subtypes of ovarian cancer. Taqman qRT-PCR performed on a subset of miRNAs confirmed results of the sequencing-based study.This report expands the body of miRNAs known to be expressed in epithelial ovarian cancer and provides a useful resource for future studies of the role of miRNAs in the pathogenesis and early detection of ovarian cancer

    Recent Acceleration of Plastid Sequence and Structural Evolution Coincides with Extreme Mitochondrial Divergence in the Angiosperm Genus Silene

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    The angiosperm genus Silene exhibits some of the most extreme and rapid divergence ever identified in mitochondrial genome architecture and nucleotide substitution rates. These patterns have been considered mitochondrial specific based on the absence of correlated changes in the small number of available nuclear and plastid gene sequences. To better assess the relationship between mitochondrial and plastid evolution, we sequenced the plastid genomes from four Silene species with fully sequenced mitochondrial genomes. We found that two species with fast-evolving mitochondrial genomes, S. noctiflora and S. conica, also exhibit accelerated rates of sequence and structural evolution in their plastid genomes. The nature of these changes, however, is markedly different from those in the mitochondrial genome. For example, in contrast to the mitochondrial pattern, which appears to be genome wide and mutationally driven, the plastid substitution rate accelerations are restricted to a subset of genes and preferentially affect nonsynonymous sites, indicating that altered selection pressures are acting on specific plastid-encoded functions in these species. Indeed, some plastid genes in S. noctiflora and S. conica show strong evidence of positive selection. In contrast, two species with more slowly evolving mitochondrial genomes, S. latifolia and S. vulgaris, have correspondingly low rates of nucleotide substitution in plastid genes as well as a plastid genome structure that has remained essentially unchanged since the origin of angiosperms. These results raise the possibility that common evolutionary forces could be shaping the extreme but distinct patterns of divergence in both organelle genomes within this genus
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