Description: The eastern tropical North Atlantic (ETNA) is characterized by a highly productive coastal upwelling system and a moderate oxygen minimum zone with lowest open ocean oxygen (O2) concentrations of around 40 μmol kg−1. Only recently, the discovery of re-occurring mesoscale eddies with sometimes close to anoxic O2 concentrations (〈1 μmol kg−1) and located just below the mixed layer challenged our understanding of O2 distribution and biogeochemical processes in this area. Here, we present the first metagenomic dataset from a deoxygenated anticyclonic modewater eddy in the open waters of the ETNA. In the eddy, we observed a significantly lower bacterial diversity compared to surrounding waters, along with a significant community shift. We detected enhanced primary productivity in the surface layer of the eddy indicated by elevated chlorophyll concentrations and increased carbon uptake rates up to three times as high as in surrounding waters. Carbon uptake below the euphotic zone correlated to the presence of a specific high-light ecotype of Prochlorococcus, which is usually underrepresented in the ETNA. Our combined data indicate that high primary production in the eddy fuels export production and the presence of a specific microbial community responsible for enhanced respiration at shallow depths, below the mixed layer base. Progressively decreasing O2 concentrations in the eddy were found to promote transcription of the key gene for denitrification, nirS, in the O2-depleted core waters. This process is usually absent from the open ETNA waters. In the light of future ocean deoxygenation our results show exemplarily that even distinct events of anoxia have the potential to alter microbial community structures and with that critically impact primary productivity and biogeochemical processes of oceanic water bodies.

Description: Dengue virus has emerged as a global health threat to over one-third of humankind. As a positive-strand RNA virus, dengue virus relies on the host cell metabolism for its translation, replication, and egress. Therefore, a better understanding of the host cell metabolic pathways required for dengue virus infection offers the opportunity to develop new approaches for therapeutic intervention. In a recently described screen of known drugs and bioactive molecules, we observed that methotrexate and floxuridine inhibited dengue virus infections at low micromolar concentrations. Here, we demonstrate that all serotypes of dengue virus, as well as West Nile virus, are highly sensitive to both methotrexate and floxuridine, whereas other RNA viruses (Sindbis virus and vesicular stomatitis virus) are not. Interestingly, flavivirus replication was restored by folinic acid, a thymidine precursor, in the presence of methotrexate and by thymidine in the presence of floxuridine, suggesting an unexpected role for thymidine in flavivirus replication. Since thymidine is not incorporated into RNA genomes, it is likely that increased thymidine production is indirectly involved in flavivirus replication. A possible mechanism is suggested by the finding that p53 inhibition restored dengue virus replication in the presence of floxuridine, consistent with thymidine-less stress triggering p53-mediated antiflavivirus effects in infected cells. Our data reveal thymidine synthesis pathways as new and unexpected therapeutic targets for antiflaviviral drug development.

Description: Objective To examine the relation between the type of stress ulcer prophylaxis administered and the risk of postoperative pneumonia in patients undergoing coronary artery bypass grafting.Design...

Description: ABSTRACT Climate information provided by global or regional climate models (RCMs) are often too coarse and prone to substantial biases for local assessments or use in impact models. Hence, statistical downscaling becomes necessary. For the Swiss National Climate Change Initiative (CH2011), a delta-change approach was used to provide daily climate scenarios at the local scale. Here, we analyse a Richardson-type weather generator (WG) as an alternative method to downscale daily precipitation, minimum and maximum temperature. The WG is calibrated for 26 Swiss stations and the reference period is 1980–2009. It is perturbed with change factors derived from RCMs (ENSEMBLES) to represent the climate of 2070–2099 assuming the SRES A1B emission scenario. The WG can be run in multi-site mode, making it especially attractive for impact-modellers that rely on a realistic spatial structure in downscaled time-series. The results from the WG are benchmarked against the original delta-change approach that applies mean additive or multiplicative adjustments to the observations. According to both downscaling methods, the results reveal mean temperature increases and a precipitation decrease in summer, consistent with earlier studies. For the summer drying, the WG indicates primarily a decrease in wet-day frequency and correspondingly an increase in mean dry spell length of between 18 and 40% at low-elevation stations. By definition, these potential changes cannot be represented by a delta-change approach. In winter, both methods project a shortening of the frost period (−30 to −60 days) and a decrease of snow days (−20 to −100%). The WG demonstrates though, that almost present-day conditions in snow-days could still occur in the future. As expected, both methods have difficulties in representing extremes. If users focus on changes in temporal sequences and need a large number of future realizations, it is recommended to use data from a WG instead of a delta-change approach.

Description: Hypertensive disorders occur in approximately 6% to 8% of all pregnancies and are a significant source of maternal and fetal morbidity. Little is known about the range of agents routinely used in practice. We used Medicaid claims from 2000 to 2007 to identify completed pregnancies. We included women who were Medicaid beneficiaries from at least 3 months prior to last menstrual period to 1 month postdelivery, and were successfully linked to infant records. Maternal exposure to antihypertensive medications was derived from Medicaid pharmacy claim files, and duration of exposure was assigned based on the days’ supply dispensed. We identified 1 106 757 Medicaid patients in our cohort, of whom 48 453 (4.4%) were exposed to antihypertensive medications during pregnancy. The prevalence of antihypertensive use increased from 3.5% to 4.9% during the study period. Antihypertensive medication users were older than nonusers, more likely to be white or black, and more likely to have comorbid diabetes mellitus and renal disease. Overall, 1.9% of pregnant women were exposed during the first trimester, 1.7% during the second trimester, and 3.2% during the third trimester. The range of antihypertensive medications to which patients were exposed was highly heterogeneous and frequently included agents other than methyldopa or labetalol. Angiotensin-converting enzyme inhibitor exposure, which is contraindicated in late pregnancy, occurred in 928 (4.9%) antihypertensive medication users in the second trimester and 383 (1.1%) in the third trimester. Antihypertensive use during pregnancy is relatively common and increasing. The wide range of agents used during pregnancy includes medications considered contraindicated during pregnancy.

Description: We read with great interest the letter to the editor by Guiu and Cercueil 1 referring to our study on invasive and non-invasive methods in quantifying liver fat content. 2 The authors commented on the MRI T2*-bias associated with presence of iron in the liver. They contend that multi-echo (ME) rather than dual-echo (DE) sequences are superior, and indicate the potential confounding effect of a relatively high flip angle and T1 bias associated with the sequences used in our study. Furthermore, they emphasise the need for international guidelines regarding sequences used by MRI for the quantification of liver fat content. Indeed, our study is compromised by the limitations of fat quantification using a standard DE sequence in comparison with the newly proposed ME-MRI with correction for T2*-bias. 3 We were aware of these limitations as the availability of these sequences is vendor-dependent and they were not...

Description: BACKGROUND Self-reported information has been used as an easy and quick method to estimate the prevalence of systemic hypertension in populations. However, verification of whether self-reports of the disease are consistent with clinical diagnosis is essential for proper use of this information. This study aimed to verify the validity and concordance between self-reported and clinical diagnosis of hypertension in the elderly population of a city in northeastern Brazil. METHODS This was a cross-sectional and population-based study. The prevalence of diagnosed and self-reported hypertension and the validity and concordance between self-reported and clinical diagnosis and their distribution according to demographic and socioeconomic variables were assessed. The validity of self-reported hypertension was determined by sensitivity, specificity, and positive and negative predictive value. RESULTS Overall, 795 elderly patients were evaluated (69.1% women). There was a high prevalence of hypertension among the elderly (diagnosed: 75.1%, 95% confidence interval (CI) = 71.1%–77.9%; self-reported: 59.7%, 95% CI = 56.3%–63.1%). For self-reported hypertension, sensitivity was substantial (77.1%), specificity was excellent (93.4%), positive predictive value was excellent (97.3%), and negative predictive value was moderate (57.2%). There was a moderate concordance between self-reported and clinical diagnosis of hypertension (kappa = 0.59; P 〈 0.001). CONCLUSIONS Reasonable validity and moderate concordance of self-reported information on hypertension was observed, which reinforces the idea that this information can be used as strategy for detecting the disease prevalence in this population. However, because of nonachievement of excellence in the validity and reliability of the measured blood pressure, this information should be carefully considered for the strategic planning of health services.

Description: Purpose: To measure B 1 field distribution in different liver segments with and without dual transmission and to quantify the contrast-to-noise ratio (CNR) between normal liver tissue and segmental venous vessels on standard clinical 3.0-T liver magnetic resonance (MR) images. Materials and Methods: This prospective study was approved by the local ethics committee. All subjects gave written informed consent. Six patients with liver lesions and nine healthy volunteers were included. Average hepatic B 1 field values in all Couinaud liver segments were assessed by using actual flip-angle imaging (first and second repetition times msec/echo time msec: 72, 192/2.2; transmission angle: 60°) for both single and dual transmission in a 3.0-T MR imaging unit that allowed both transmission modes. Additionally, two-dimensional T1-weighted gradient-echo (repetition time msec/echo time msec, 180/2.3; transmission angle, 55°) and T2-weighted single-shot fast spin-echo images (1501/80) were acquired. Average CNR between liver parenchyma and segmental veins were measured in each segment. Two-sided paired Student t tests were used for statistical evaluation. Two blinded radiologists independently identified lesions in images from acquisitions in both transmission modes. Results: Mean flip angles achieved with conventional single transmission were 44%–53% of the nominal value in segments II–IV and 67% and 63% of the nominal value in segments VI and VII, respectively, and were less than 77% in all segments. Mean actual flip angles measured for dual transmission were between 82% and 100% of the nominal value in all segments. T1-weighted single-transmission images exhibited areas of low B 1 field strength with reduced image contrast. T2-weighted single-transmission images displayed significantly reduced signal intensity but nearly unchanged contrast weighting in these areas. On T1-weighted dual-transmission images, the two readers detected 22 and 14 additional lesions that they did not identify on the single-transmission images. On the dual-transmission T2-weighted images, they detected 11 and five additional lesions, respectively. Conclusion: Dual transmission can generate a B 1 field with significantly improved homogeneity over all liver segments at a field strength of 3.0 T. © RSNA, 2012 Supplemental material: http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.12112715/-/DC1

Description: A group of 400–500 m long, bedding-parallel calcite veins are exposed in the central La Popa Basin of northeastern Mexico. These veins provide a unique opportunity to determine the kilometer-scale fluid–rock system associated with bedding-parallel vein formation, and to test for sampling bias in studies that often use one or two samples to constrain the characteristics of regional-scale paleohydrogeological systems. We use fluid inclusion microthermometry in conjunction with measurements of δ 13 C, δ 18 O, and 87 Sr/ 86 Sr ratios to constrain the vein-forming fluid temperatures, compositions and sources, and compare these values along and between the veins to establish the homogeneity of the vein-forming fluids and fluid–rock system. The δ 13 C values of the veins are close to those of the host rock, and average – 3.96‰ (PDB). The δ 18 O values of the veins are typically 1‰ lower than those of the host rocks, and average – 9.54‰ (PDB). Fluid inclusion homogenization temperatures average 137°C and inclusion salinities are all 〈6 wt% NaCl equivalent. The 87 Sr/ 86 Sr ratios of the veins average 0.70731 and are substantially lower than the values expected for the host rock. Calculated fluid δ 18 O values range from 4 to 10‰ (SMOW). The isotopic and microthermometric data indicate the veins most likely formed at depths of 3–4 km when meteoric water mixed with upward migrating, warm basinal brines. Vein microstructures and field characteristics indicate they formed from multiple slip events that most likely were associated with transport of individual fluid pulses that migrated along bedding planes. The large-scale homogeneity of vein geochemistry is remarkable and demonstrates that only one or two samples would be sufficient to accurately characterize the kilometer-scale paleohydrogeological system for these veins. We conducted petrographic, isotopic, and fluid inclusion analyses on a set of bed-parallel veins that can be traced for over 400 m. The results indicate that the vein-forming fluids were homogeneous and derived from downward-percolating meteoric water and upward-flowing, low salinity, basinal brine. The paleohydrological system that formed the veins was uniform at scales of hundreds of meters to kilometers.

Description: Purpose: To compare lumbar muscle fat-signal fractions derived from three-dimensional dual gradient-echo magnetic resonance (MR) imaging and multiple gradient-echo MR imaging with fractions from single-voxel MR spectroscopy in patients with low back pain. Materials and Methods: This prospective study had institutional review board approval, and written informed consent was obtained from all study participants. Fifty-six patients (32 women; mean age, 52 years ± 15 [standard deviation]; age range, 20–79 years) with low back pain underwent standard 1.5-T MR imaging, which was supplemented by dual-echo MR imaging, multi-echo MR imaging, and MR spectroscopy to quantify fatty degeneration of bilateral lumbar multifidus muscles in a region of interest at the intervertebral level of L4 through L5. Fat-signal fractions were determined from signal intensities on fat- and water-only images from both imaging data sets (dual-echo and multi-echo fat-signal fractions without T2* correction) or directly obtained, with additional T2* correction, from multi-echo MR imaging. The results were compared with MR spectroscopic fractions. The Student t test and Bland-Altman plots were used to quantify agreement between fat-signal fractions derived from imaging and from spectroscopy. Results: In total, 102 spectroscopic measurements were obtained bilaterally (46 of 56) or unilaterally (10 of 56). Mean spectroscopic fat-signal fraction was 19.6 ± 11.4 (range, 5.4–63.5). Correlation between spectroscopic and all imaging-based fat-signal fractions was statistically significant ( R 2 = 0.87–0.92; all P 〈 .001). Mean dual-echo fat-signal fractions not corrected for T2* and multi-echo fat-signal fractions corrected for T2* significantly differed from spectroscopic fractions (both P 〈 .01), but mean multi-echo fractions not corrected for T2* did not ( P = .11). There was a small measurement bias of 0.5% (95% limits of agreement: –6.0%, 7.2%) compared with spectroscopic fractions. Conclusion: Large-volume image-based (dual-echo and multi-echo MR imaging) and spectroscopic fat-signal fractions agree well, thus allowing fast and accurate quantification of muscle fat content in patients with low back pain. © RSNA, 2012