27 research outputs found
A gas density drop in the inner 6 AU of the transition disk around the Herbig Ae star HD 139614
A. Carmona was partly supported by the Spanish Grant AYA 2011-26202. A. Carmona, A. Kospal and Zs. Regaly were partly supported by the Momentum grant of the MTA CSFK Lendulet Disk Research Group of the Hungarian Academy of Sciences. A. Carmona and C. Pinte acknowledge funding from the European Commission’s 7th Framework Program (ECFP7) (contract PERG06-GA-2009-256513) and from Agence Nationale pour la Recherche (ANR) of France under contract ANR-2010-JCJC-0504-01. A. Carmona acknowledges financial support by the European Southern Observatory visitors program. The research leading to these results has received funding from the EC-FP7 under grant agreement no 284405. C. Eiroa is partly supported by the Spanish Grant AYA 2014-55840-P L. A. Cieza was supported by CONICYT-FONDECYT grant number 1140109 and the Millennium Science Initiative (Chilean Ministry of Economy), through grant Nucleus RC130007.Context. Quantifying the gas surface density inside the dust cavities and gaps of transition disks is important to establish their origin. Aims. We seek to constrain the surface density of warm gas in the inner disk of HD 139614, an accreting 9 Myr Herbig Ae star with a (pre-)transition disk exhibiting a dust gap from 2.30.1 to 5.60.3 AU. Methods. We observed HD 139614 with ESO/VLT CRIRES and obtained high-resolution (R~90 000) spectra of CO isotopologues ro-vibrational emission at 4.7 μm. We derive constraints on the disk’s structure by modeling the CO isotopologue line profiles, the spectroastrometric signal, and the rotational diagrams using grids of flat Keplerian disk models. Results. We detected v = 1 → 0 12CO, 2→1 12CO, 1→0 13CO, 1→0 C18O, and 1→0 C17O ro-vibrational lines. Lines are consistent with disk emission and thermal excitation. 12CO v = 1→ 0 lines have an average width of 14 km s-1, Tgas of 450 K and an emitting region from 1 to 15 AU. 13CO and C18O lines are on average 70 and 100 K colder, 1 and 4 km s-1 narrower than 12CO v = 1→ 0, and are dominated by emission at R ≥ 6 AU. The 12CO = 1 → 0 composite line profile indicates that if there is a gap devoid of gas it must have a width narrower than 2 AU. We find that a drop in the gas surface density (δgas) at R = 5 — 6 AU is required to be able to reproduce the line profiles and rotational diagrams of the three CO isotopologues simultaneously. Models without a gas density drop generate 13CO and C18O emission lines that are too broad and warm. The value of gas can range from 10-2 to 10-4 depending on the gas-to-dust ratio of the outer disk. We find that the gas surface density profile at 1 2 AU) gas gap suggest the presence of an embedded < 2 MJ planet at around 4 AU.PostprintPeer reviewe
A Mouse Model of Acrodermatitis Enteropathica: Loss of Intestine Zinc Transporter ZIP4 (Slc39a4) Disrupts the Stem Cell Niche and Intestine Integrity
Loss-of-function of the zinc transporter ZIP4 in the mouse intestine mimics the lethal human disease acrodermatitis enteropathica. This is a rare disease in humans that is not well understood. Our studies demonstrate the paramount importance of ZIP4 in the intestine in this disease and reveal that a root cause of lethality is disruption of the intestine stem cell niche and impaired function of the small intestine. This, in turn, leads to dramatic weight loss and death unless treated with exogenous zinc
Spatial patterns of white matter hyperintensities associated with Alzheimer's disease risk factors in a cognitively healthy middle-aged cohort
Background
White matter hyperintensities (WMH) of presumed vascular origin have been associated with an increased risk of Alzheimer’s disease (AD). This study aims to describe the patterns of WMH associated with dementia risk estimates and individual risk factors in a cohort of middle-aged/late middle-aged individuals (mean 58 (interquartile range 51–64) years old).
Methods
Magnetic resonance imaging and AD risk factors were collected from 575 cognitively unimpaired participants. WMH load was automatically calculated in each brain lobe and in four equidistant layers from the ventricular surface to the cortical interface. Global volumes and regional patterns of WMH load were analyzed as a function of the Cardiovascular Risk Factors, Aging and Incidence of Dementia (CAIDE) dementia risk score, as well as family history of AD and Apolipoprotein E (APOE) genotype. Additional analyses were performed after correcting for the effect of age and hypertension.
Results
The studied cohort showed very low WMH burden (median 1.94 cm3) and 20-year dementia risk estimates (median 1.47 %). Even so, higher CAIDE scores were significantly associated with increased global WMH load. The main drivers of this association were age and hypertension, with hypercholesterolemia and body mass index also displaying a minor, albeit significant, influence. Regionally, CAIDE scores were positively associated with WMH in anterior areas, mostly in the frontal lobe. Age and hypertension showed significant association with WMH in almost all regions analyzed. The APOE-ε2 allele showed a protective effect over global WMH with a pattern that comprised juxtacortical temporo-occipital and fronto-parietal deep white matter regions. Participants with maternal family history of AD had higher WMH load than those without, especially in temporal and occipital lobes.
Conclusions
WMH load is associated with AD risk factors even in cognitively unimpaired subjects with very low WMH burden and dementia risk estimates. Our results suggest that tight control of modifiable risk factors in middle-age/late middle-age could have a significant impact on late-life dementia
White matter hyperintensities mediate gray matter volume and processing speed relationship in cognitively unimpaired participants
White matter hyperintensities (WMH) have been extensively associated with cognitive impairment and reductions in gray matter volume (GMv) independently. This study explored whether WMH lesion volume mediates the relationship between cerebral patterns of GMv and cognition in 521 (mean age 57.7 years) cognitively unimpaired middle‐aged individuals. Episodic memory (EM) was measured with the Memory Binding Test and executive functions (EF) using five WAIS‐IV subtests. WMH were automatically determined from T2 and FLAIR sequences and characterized using diffusion‐weighted imaging (DWI) parameters. WMH volume was entered as a mediator in a voxel‐wise mediation analysis relating GMv and cognitive performance (with both EM and EF composites and the individual tests independently). The mediation model was corrected by age, sex, education, number of Apolipoprotein E (APOE)‐ε4 alleles and total intracranial volume. We found that even at very low levels of WMH burden in the cohort (median volume of 3.2 mL), higher WMH lesion volume was significantly associated with a widespread pattern of lower GMv in temporal, frontal, and cerebellar areas. WMH mediated the relationship between GMv and EF, mainly driven by processing speed, but not EM. DWI parameters in these lesions were compatible with incipient demyelination and axonal loss. These findings lead to the reflection on the relevance of the control of cardiovascular risk factors in middle‐aged individuals as a valuable preventive strategy to reduce or delay cognitive decline
Long-term impact of diabetes in patients with ST-segment elevation myocardial infarction: Insights from the EXAMINATION randomized trial
Background: Long-term outcomes of diabetic patients suffering from ST-segment elevation myocardial infarction (STEMI) and treated with second-generation drug-eluting stent have been scarcely evaluated. The aim of this posthoc subanalysis of the EXAMINATION trial was to compare 5-year outcomes according to the presence of diabetes mellitus. Methods: From a total of 1,497 patients included in the trial, 258 were diabetics (n = 137, received everolimus-eluting stent (EES) and n = 121 bare-metal stent (BMS); whereas 1,239 were nondiabetics (n = 613 treated with EES and n = 626 with BMS). Patient-oriented combined endpoint (POCE) defined as all-cause death, any MI or any revascularization, and other clinical parameters were collected up to 5-years. All results were adjusted for various potential confounders. Results: At 5-years, patients with diabetes showed similar rates of POCE between diabetics treated with EES and those treated with BMS (32.8% vs. 32.2%; p = 0.88). However, rates of TLR were significantly lower in the EES group (4.4% vs. 9.9%; HR 0.52 (0.29–0.94); P = 0.03). In non-diabetics, the use of EES was associated with a significant improvement in all-clinical parameters except for MI rate: POCE: [10.0% vs. 12.6%; HR 0.78(0.62–0.98); P = 0.038], all cause death: [7.0% vs. 12.1%; HR 0.62(0.42–0.90); P = 0.014], and [TLR: 4.2 vs. 6.7; HR 0.60 (0.37–0.98); P = 0.04]. Overall, diabetics showed higher rate of POCE at 5-years (32.6% vs. 21.5% in nondiabetics HR1.45[1.03–2.04];p = 0.03) driven by increased rates of MI and the need for revascularization that occurred in coronary segments remote from target lesions [2.7% vs. 1.1%; HR: 2.27 (1.12–5.23); P = 0.02 and 14% vs. 6.2%; HR: 2.11 (1.38–3.22); P = 0.001, respectively]. Conclusions: Diabetics had worse clinical outcomes than nondiabetics after STEMI mainly due to atherosclerosis progression. At 5-years, the treatment with EES did not reduce the rate of POCE in diabetics but reduced the need for revascularization compared with BMS
Evidence for allosteric regulation of pH-sensitive System A (SNAT2) and System N (SNAT5) amino acid transporter activity involving a conserved histidine residue
System A and N amino acid transporters are key effectors of movement of amino acids across the plasma membrane of mammalian cells. These Na(+)-dependent transporters of the SLC38 gene family are highly sensitive to changes in pH within the physiological range, with transport markedly depressed at pH 7.0. We have investigated the possible role of histidine residues in the transporter proteins in determining this pH-sensitivity. The histidine-modifying agent DEPC (diethyl pyrocarbonate) markedly reduces the pH-sensitivity of SNAT2 and SNAT5 transporters (representative isoforms of System A and N respectively, overexpressed in Xenopus oocytes) in a concentration-dependent manner but does not completely inactivate transport activity. These effects of DEPC were reversed by hydroxylamine and partially blocked in the presence of excess amino acid substrate. DEPC treatment also blocked a reduction in apparent affinity for Na(+) (K(0.5)(Na(+))) of the SNAT2 transporter at low external pH. Mutation of the highly conserved C-terminal histidine residue to alanine in either SNAT2 (H504A) or SNAT5 (H471A) produced a transport phenotype exhibiting reduced, DEPC-resistant pH-sensitivity with no change in K(0.5)(Na(+)) at low external pH. We suggest that the pH-sensitivity of these structurally related transporters results at least partly from a common allosteric mechanism influencing Na(+) binding, which involves an H(+)-modifier site associated with C-terminal histidine residues
Zinc ions have a potential to attenuate both Ni ion uptake and Ni ion-induced inflammation
Hypermanganesemia due to mutations in SLC39A14: further insights into Mn deposition in the central nervous system
Abstract Background The SLC39A14, SLC30A10 and SLC39A8 are considered to be key genes involved in manganese (Mn) homeostasis in humans. Mn levels in plasma and urine are useful tools for early recognition of these disorders. We aimed to explore further biomarkers of Mn deposition in the central nervous system in two siblings presenting with acute dystonia and hypermanganesemia due to mutations in SLC39A14. These biomarkers may help clinicians to establish faster and accurate diagnosis and to monitor disease progression after chelation therapy is administered. Results A customized gene panel for movement disorders revealed a novel missense variant (c.311G > T; p.Ser104Ile) in SLC39A14 gene in two siblings presenting at the age of 10 months with acute dystonia and motor regression. Mn concentrations were analyzed using inductively coupled mass spectrometry in plasma and cerebrospinal fluid, disclosing elevated Mn levels in the index case compared to control patients. Surprisingly, Mn values were 3-fold higher in CSF than in plasma. We quantified the pallidal index, defined as the ratio between the signal intensity in the globus pallidus and the subcortical frontal white matter in axial T1-weighted MRI, and found significantly higher values in the SLC39A14 patient than in controls. These values increased over a period of 10 years, suggesting the relentless pallidal accumulation of Mn. Following genetic confirmation, a trial with the Mn chelator Na2CaEDTA led to a reduction in plasma Mn, zinc and selenium levels. However, parents reported worsening of cervical dystonia, irritability and sleep difficulties and chelation therapy was discontinued. Conclusions Our study expands the very few descriptions of patients with SLC39A14 mutations. We report for the first time the elevation of Mn in CSF of SLC39A14 mutated patients, supporting the hypothesis that brain is an important organ of Mn deposition in SLC39A14-related disease. The pallidal index is an indirect and non-invasive method that can be used to rate disease progression on follow-up MRIs. Finally, we propose that patients with inherited defects of manganese transport should be initially treated with low doses of Na2CaEDTA followed by gradual dose escalation, together with a close monitoring of blood trace elements in order to avoid side effects
Artículo especial Guía ESC 2015 sobre el diagnóstico y tratamiento de las enfermedades del pericardio: Grupo de Trabajo de la Sociedad Europea de Cardiología (ESC) para el diagnóstico y tratamiento de las enfermedades del pericardio
[No abstract available