2,589 research outputs found
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Coenzyme Q10 deficiencies: pathways in yeast and humans.
Coenzyme Q (ubiquinone or CoQ) is an essential lipid that plays a role in mitochondrial respiratory electron transport and serves as an important antioxidant. In human and yeast cells, CoQ synthesis derives from aromatic ring precursors and the isoprene biosynthetic pathway. Saccharomyces cerevisiae coq mutants provide a powerful model for our understanding of CoQ biosynthesis. This review focusses on the biosynthesis of CoQ in yeast and the relevance of this model to CoQ biosynthesis in human cells. The COQ1-COQ11 yeast genes are required for efficient biosynthesis of yeast CoQ. Expression of human homologs of yeast COQ1-COQ10 genes restore CoQ biosynthesis in the corresponding yeast coq mutants, indicating profound functional conservation. Thus, yeast provides a simple yet effective model to investigate and define the function and possible pathology of human COQ (yeast or human gene involved in CoQ biosynthesis) gene polymorphisms and mutations. Biosynthesis of CoQ in yeast and human cells depends on high molecular mass multisubunit complexes consisting of several of the COQ gene products, as well as CoQ itself and CoQ intermediates. The CoQ synthome in yeast or Complex Q in human cells, is essential for de novo biosynthesis of CoQ. Although some human CoQ deficiencies respond to dietary supplementation with CoQ, in general the uptake and assimilation of this very hydrophobic lipid is inefficient. Simple natural products may serve as alternate ring precursors in CoQ biosynthesis in both yeast and human cells, and these compounds may act to enhance biosynthesis of CoQ or may bypass certain deficient steps in the CoQ biosynthetic pathway
Parents\u27 perception of stroller use in young children: A qualitative study
Background: Despite their wide usage, it has recently been suggested that stroller use may reduce physical activity levels of young children. However, there have been no studies on stroller use as it relates to physical activity outcomes. The objectives of this study were to understand the context of stroller use for young children and parents\u27 perceptions of the relationship between stroller use and their children\u27s physical activity. Methods: Parents of children 1 to 5 years of age were recruited through two sites of TARGet Kids!, a primary-care, practice-based research network in Toronto, Canada. Fourteen semi-structured interviews were conducted. Interviews were audio recorded and transcribed verbatim and two independent reviewers conducted thematic analysis. A number of strategies were employed to ensure the trustworthiness of the data. Results: Parents discussed reasons for stroller use (i.e., transportation; storage; leisure; supervision/confinement; parent physical activity; and sleep), factors that influence the decision to use a stroller (i.e., caregiver choice; convenience, timing, distance; family lifestyle; and child preference), and perceived impact of stroller use on physical activity (i.e., most parents did not recognize a connection between stroller use and physical activity). Conclusion: This study provides a context for researchers and policy makers to consider when developing stroller related physical activity guidelines for young children
Treatments for hyperemesis gravidarum and nausea and vomiting in pregnancy:A systematic review and economic assessment
Background: Nausea and vomiting in pregnancy (NVP) affects up to 85% of all women during pregnancy, but for the majority self-management suffices. For the remainder, symptoms are more severe and the most severe form of NVP – hyperemesis gravidarum (HG) – affects 0.3–1.0% of pregnant women. There is no widely accepted point at which NVP becomes HG. Objectives: This study aimed to determine the relative clinical effectiveness and cost-effectiveness of treatments for NVP and HG. Data sources: MEDLINE, EMBASE, Cumulative Index to Nursing and Allied Health Literature, Cochrane Central Register of Controlled Trials, PsycINFO, Commonwealth Agricultural Bureaux (CAB) Abstracts, Latin American and Caribbean Health Sciences Literature, Allied and Complementary Medicine Database, British Nursing Index, Science Citation Index, Social Sciences Citation Index, Scopus, Conference Proceedings Index, NHS Economic Evaluation Database, Health Economic Evaluations Database, China National Knowledge Infrastructure, Cochrane Database of Systematic Reviews and Database of Abstracts of Reviews of Effects were searched from inception to September 2014. References from studies and literature reviews identified were also examined. Obstetric Medicine was hand-searched, as were websites of relevant organisations. Costs came from NHS sources. Review methods: A systematic review of randomised and non-randomised controlled trials (RCTs) for effectiveness, and population-based case series for adverse events and fetal outcomes. Treatments: vitamins B6 and B12, ginger, acupressure/acupuncture, hypnotherapy, antiemetics, dopamine antagonists, 5-hydroxytryptamine receptor antagonists, intravenous (i.v.) fluids, corticosteroids, enteral and parenteral feeding or other novel treatment. Two reviewers extracted data and quality assessed studies. Results were narratively synthesised; planned meta-analysis was not possible due to heterogeneity and incomplete reporting. A simple economic evaluation considered the implied values of treatments. Results: Seventy-three studies (75 reports) met the inclusion criteria. For RCTs, 33 and 11 studies had a low and high risk of bias respectively. For the remainder (n = 20) it was unclear. The non-randomised studies (n = 9) were low quality. There were 33 separate comparators. The most common were acupressure versus placebo (n = 12); steroid versus usual treatment (n = 7); ginger versus placebo (n = 6); ginger versus vitamin B6 (n = 6); and vitamin B6 versus placebo (n = 4). There was evidence that ginger, antihistamines, metoclopramide (mild disease) and vitamin B6 (mild to severe disease) are better than placebo. Diclectin® [Duchesnay Inc.; doxylamine succinate (10 mg) plus pyridoxine hydrochloride (10 mg) slow release tablet] is more effective than placebo and ondansetron is more effective at reducing nausea than pyridoxine plus doxylamine. Diclectin before symptoms of NVP begin for women at high risk of severe NVP recurrence reduces risk of moderate/severe NVP compared with taking Diclectin once symptoms begin. Promethazine is as, and ondansetron is more, effective than metoclopramide for severe NVP/HG. I.v. fluids help correct dehydration and improve symptoms. Dextrose saline may be more effective at reducing nausea than normal saline. Transdermal clonidine patches may be effective for severe HG. Enteral feeding is effective but extreme method treatment for very severe symptoms. Day case management for moderate/severe symptoms is feasible, acceptable and as effective as inpatient care. For all other interventions and comparisons, evidence is unclear. The economic analysis was limited by lack of effectiveness data, but comparison of costs between treatments highlights the implications of different choices. Limitations: The main limitations were the quantity and quality of the data available. Conclusion: There was evidence of some improvement in symptoms for some treatments, but these data may not be transferable across disease severities. Methodologically sound and larger trials of the main therapies considered within the UK NHS are needed. Study registration: This study is registered as PROSPERO CRD42013006642. Funding: The National Institute for Health Research Health Technology Assessment programme
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Aging is associated with positive responding to neutral information but reduced recovery from negative information
Studies on aging and emotion suggest an increase in reported positive affect, a processing bias of positive over negative information, as well as increasingly adaptive regulation in response to negative events with advancing age. These findings imply that older individuals evaluate information differently, resulting in lowered reactivity to, and/or faster recovery from, negative information, while maintaining more positive responding to positive information. We examined this hypothesis in an ongoing study on Midlife in the US (MIDUS II) where emotional reactivity and recovery were assessed in a large number of respondents (N = 159) from a wide age range (36–84 years). We recorded eye-blink startle magnitudes and corrugator activity during and after the presentation of positive, neutral and negative pictures. The most robust age effect was found in response to neutral stimuli, where increasing age is associated with a decreased corrugator and eyeblink startle response to neutral stimuli. These data suggest that an age-related positivity effect does not essentially alter the response to emotion-laden information, but is reflected in a more positive interpretation of affectively ambiguous information. Furthermore, older women showed reduced corrugator recovery from negative pictures relative to the younger women and men, suggesting that an age-related prioritization of well-being is not necessarily reflected in adaptive regulation of negative affect
Systematic Bias in Helioseismic Measurements of Meridional Circulation Arising from Nonlocal Averaging Kernels
Meridional circulation in the solar convection zone plays a profound role in
regulating the interior dynamics of the Sun and its magnetism. While it is well
accepted that meridional flows move from the equator towards the poles at the
Sun's surface, helioseismic observations have yet to provide a definitive
answer for the depth at which those flows return to the equator, or the number
of circulation cells in depth. In this work, we investigate whether the
discrepancies regarding the nature of the return flow are intrinsic to how
helioseismic observations are made. We examine the seismic signature of
possible meridional flow profiles by convolving time-distance averaging kernels
with the mean flows obtained from 3-D hydrodynamic simulations of the solar
convection zone. At mid and high latitudes, we find that weak flow structures
in the deeper regions of the convection zone can be strongly obscured by signal
from the much stronger surface flows. This contamination is the result of
extended side lobes in the averaging kernels and generates a spurious
equatorward signal of 2--3 m s at those latitudes, and at depth. At low latitudes, however, the flows in the simulations
tend to be stronger and multiple cells across the shell depth can produce a
sufficiently strong seismic signal to survive the convolution process. The
signal associated with the deep equatorward return flow in the Sun is expected
to be weak and in the same sense as the contamination from the surface. Hence,
the return flow needs to exceed -- in magnitude
for reported detections to be considered significant.Comment: Submitted to AAS Journal
Genes and lipids that impact uptake and assimilation of exogenous coenzyme Q in Saccharomyces cerevisiae.
Coenzyme Q (CoQ) is an essential player in the respiratory electron transport chain and is the only lipid-soluble antioxidant synthesized endogenously in mammalian and yeast cells. In humans, genetic mutations, pathologies, certain medical treatments, and aging, result in CoQ deficiencies, which are linked to mitochondrial, cardiovascular, and neurodegenerative diseases. The only strategy available for these patients is CoQ supplementation. CoQ supplements benefit a small subset of patients, but the poor solubility of CoQ greatly limits treatment efficacy. Consequently, the efficient delivery of CoQ to the mitochondria and restoration of respiratory function remains a major challenge. A better understanding of CoQ uptake and mitochondrial delivery is crucial to make this molecule a more efficient and effective therapeutic tool. In this study, we investigated the mechanism of CoQ uptake and distribution using the yeast Saccharomyces cerevisiae as a model organism. The addition of exogenous CoQ was tested for the ability to restore growth on non-fermentable medium in several strains that lack CoQ synthesis (coq mutants). Surprisingly, we discovered that the presence of CoQ biosynthetic intermediates impairs assimilation of CoQ into a functional respiratory chain in yeast cells. Moreover, a screen of 40 gene deletions considered to be candidates to prevent exogenous CoQ from rescuing growth of the CoQ-less coq2Δ mutant, identified six novel genes (CDC10, RTS1, RVS161, RVS167, VPS1, and NAT3) as necessary for efficient trafficking of CoQ to mitochondria. The proteins encoded by these genes represent essential steps in the pathways responsible for transport of exogenously supplied CoQ to its functional sites in the cell, and definitively associate CoQ distribution with endocytosis and intracellular vesicular trafficking pathways conserved from yeast to human cells
Predicting Chandra CCD Degradation with the Chandra Radiation Model
Not long after launch of the Chandra X-Ray Observatory, it was discovered that the Advanced CCD Imaging Spectrometer (ACIS) detector was rapidly degrading due to radiation. Analysis by Chandra personnel showed that this degradation was due to 10w energy protons (100 - 200 keV) that scattered down the optical path onto the focal plane. In response to this unexpected problem, the Chandra Team developed a radiation-protection program that has been used to manage the radiation damage to the CCDs. This program consists of multiple approaches - scheduled sating of the ACIS detector from the radiation environment during passage through radiation belts, real-time monitoring of space weather conditions, on-board monitoring of radiation environment levels, and the creation of a radiation environment model for use in computing proton flux and fluence at energies that damage the ACIS detector. This radiation mitigation program has been very successful. The initial precipitous increase in the CCDs' charge transfer inefficiency (CTI) resulting from proton damage has been slowed dramatically, with the front-illuminated CCDS having an increase in CTI of only 2.3% per year, allowing the ASIS detector's expected lifetime to exceed requirements. This paper concentrates on one aspect of the Chandra radiation mitigation program, the creation of the Chandra Radiation Model (CRM). Because of Chandra's highly elliptical orbit, the spacecraft spends most of its time outside of the trapped radiation belts that present the severest risks to the ACIS detector. However, there is still a proton flux environment that must be accounted for in all parts of Chandra's orbit. At the time of Chandra's launch there was no engineering model of the radiation environment that could be used in the outer regions of the spacecraft's orbit, so the CRM was developed to provide the flux environment of 100 - 200 keV protons in the outer magnetosphere, magnetosheath, and solar wind regions of geospace. This presentation describes CRM, its role in Chandra operations, and its prediction of the ACIS CTI increase
Treatments for Hyperemesis Gravidarum and Nausea and Vomiting in Pregnancy
Importance Nausea and vomiting affects approximately 85% of pregnant women. The most severe form, hyperemesis gravidarum, affects up to 3% of women and can have significant adverse physical and psychological sequelae.Objective To summarize current evidence on effective treatments for nausea and vomiting in pregnancy and hyperemesis gravidarum.Evidence Review Databases were searched to June 8, 2016. Relevant websites and bibliographies were also searched. Titles and abstracts were assessed independently by 2 reviewers. Results were narratively synthesized; planned meta-analysis was not possible because of heterogeneity and incomplete reporting of findings.Findings Seventy-eight studies (n = 8930 participants) were included: 67 randomized clinical trials (RCTs) and 11 nonrandomized studies. Evidence from 35 RCTs at low risk of bias indicated that ginger, vitamin B6, antihistamines, metoclopramide (for mild symptoms), pyridoxine-doxylamine, and ondansetron (for moderate symptoms) were associated with improved symptoms compared with placebo. One RCT (n = 86) reported greater improvements in moderate symptoms following psychotherapy (change in Rhodes score [range, 0 {no symptoms} to 40 {worst possible symptoms}], 18.76 [SD, 5.48] to 7.06 [SD, 5.79] for intervention vs 19.18 [SD, 5.63] to 12.81 [SD, 6.88] for comparator [P < .001]). For moderate-severe symptoms, 1 RCT (n = 60) suggested that pyridoxine-doxylamine combination taken preemptively reduced risk of recurrence of moderate-severe symptoms compared with treatment once symptoms begin (15.4% vs 39.1% [P < .04]). One RCT (n = 83) found that ondansetron was associated with lower nausea scores on day 4 than metoclopramide (mean visual analog scale [VAS] score, 4.1 [SD, 2.9] for ondansetron vs 5.7 [SD, 2.3] for metoclopramide [P = .023]) but not episodes of emesis (5.0 [SD, 3.1] vs 3.3 [SD, 3], respectively [P = .013]). Although there was no difference in trend in nausea scores over the 14-day study period, trend in vomiting scores was better in the ondansetron group (P = .042). One RCT (n = 159) found no difference between metoclopramide and promethazine after 24 hours (episodes of vomiting, 1 [IQR, 0-5] for metoclopramide vs 2 [IQR, 0-3] for promethazine [P = .81], VAS [0-10 scale] for nausea, 2 [IQR, 1-5] vs 2 [IQR, 1-4], respectively [P = .99]). Three RCTs compared corticosteroids with placebo or promethazine or metoclopramide in women with severe symptoms. Improvements were seen in all corticosteroid groups, but only a significant difference between corticosteroids vs metoclopramide was reported (emesis reduction, 40.9% vs 16.5% at day 2; 71.6% vs 51.2% at day 3; 95.8% vs 76.6% at day 7 [n = 40, P < .001]). For other interventions, evidence was limited.Conclusions and Relevance For mild symptoms of nausea and emesis of pregnancy, ginger, pyridoxine, antihistamines, and metoclopramide were associated with greater benefit than placebo. For moderate symptoms, pyridoxine-doxylamine, promethazine, and metoclopramide were associated with greater benefit than placebo. Ondansetron was associated with improvement for a range of symptom severity. Corticosteroids may be associated with benefit in severe cases. Overall the quality of evidence was low
Optical Monitoring of the Broad-Line Radio Galaxy 3C390.3
We have undertaken a new ground-based monitoring campaign on the BLRG 3C390.3
to improve the measurement of the size of the BLR and to estimate the black
hole mass. Optical spectra and g-band images were observed in 2005 using the
2.4m telescope at MDM Observatory. Integrated emission-line flux variations
were measured for Ha, Hb, Hg, and for HeII4686, as well as g-band fluxes and
the optical AGN continuum at 5100A. The g-band fluxes and the AGN continuum
vary simultaneously within the uncertainties, tau=(0.2+-1.1)days. We find that
the emission-line variations are delayed with respect to the variable g-band
continuum by tau(Ha)=56.3(+2.4-6.6)days, tau(Hb)=44.3(+3.0_-3.3)days,
tau(Hg)=58.1(+4.3-6.1)days, and tau(HeII4686)=22.3(+6.5-3.8)days. The blue and
red peak in the double peaked line profiles, as well as the blue and red outer
profile wings, vary simultaneously within +-3 days. This provides strong
support for gravitationally bound orbital motion of the dominant part of the
line emitting gas. Combining the time delay of Ha and Hb and the separation of
the blue and red peak in the broad double-peaked profiles in their rms spectra,
we determine Mbh_vir=1.77(+0.29-0.31)x10^8Msol and using sigma_line of the rms
spectra Mbh_vir=2.60(+0.23-0.31)x10^8Msol for the central black hole of
3C390.3, respectively. Using the inclination angle of the line emitting region
the mass of the black hole amounts to Mbh=0.86(+0.19-0.18)x10^9 Msol
(peak-separation) and Mbh=1.26(+0.21-0.16)x10^9 Msol (sigma_line),
respectively. This result is consistent with the black hole masses indicated by
simple accretion disk models to describe the observed double-peaked profiles,
derived from the stellar dynamics of 3C390.3, and with the AGN
radius-luminosity relation. Thus, 3C390.3 as a radio-loud AGN with a low
Eddington ratio, Ledd/Lbol=0.02, follows the same AGN radius-luminosity
relation as radio-quiet AGN.Comment: accepted, scheduled for September 20, 2012, ApJ 75
The York Gospels: a 1000-year biological palimpsest.
Medieval manuscripts, carefully curated and conserved, represent not only an irreplaceable documentary record but also a remarkable reservoir of biological information. Palaeographic and codicological investigation can often locate and date these documents with remarkable precision. The York Gospels (York Minster Ms. Add. 1) is one such codex, one of only a small collection of pre-conquest Gospel books to have survived the Reformation. By extending the non-invasive triboelectric (eraser-based) sampling technique eZooMS, to include the analysis of DNA, we report a cost-effective and simple-to-use biomolecular sampling technique for parchment. We apply this combined methodology to document for the first time a rich palimpsest of biological information contained within the York Gospels, which has accumulated over the 1000-year lifespan of this cherished object that remains an active participant in the life of York Minster. These biological data provide insights into the decisions made in the selection of materials, the construction of the codex and the use history of the object
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