Search

Objective: Recognizing that the interrelationships between chronic conditions that complicate rheumatoid arthritis (RA) are poorly understood, we aimed to identify patterns of multimorbidity and to define their prevalence in RA through machine learning. Methods: We constructed RA and age‐ and sex‐matched (1:1) non‐RA cohorts within a large commercial insurance database (MarketScan) and the Veterans Health Administration (VHA). Chronic conditions (n = 44) were identified from diagnosis codes from outpatient and inpatient encounters. Exploratory factor analysis was performed separately in both databases, stratified by RA diagnosis and sex, to identify multimorbidity patterns. The association of RA with different multimorbidity patterns was determined using conditional logistic regression. Results: We studied 226,850 patients in MarketScan (76% female) and 120,780 patients in the VHA (89% male). The primary multimorbidity patterns identified were characterized by the presence of cardiopulmonary, cardiometabolic, and mental health and chronic pain disorders. Multimorbidity patterns were similar between RA and non‐RA patients, female and male patients, and patients in MarketScan and the VHA. RA patients had higher odds of each multimorbidity pattern (odds ratios [ORs] 1.17–2.96), with mental health and chronic pain disorders being the multimorbidity pattern most strongly associated with RA (ORs 2.07–2.96). Conclusion: Cardiopulmonary, cardiometabolic, and mental health and chronic pain disorders represent predominant multimorbidity patterns, each of which is overrepresented in RA. The identification of multimorbidity patterns occurring more frequently in RA is an important first step in progressing toward a holistic approach to RA management and warrants assessment of their clinical and predictive utility. [ABSTRACT FROM AUTHOR]

Background: Most COVID‐19‐associated mucormycosis (CAM) cases are reported from India and neighbouring countries. Anecdotally cases from Europe have been presented. Objective: To estimate the disease burden and describe the clinical presentation of CAM in Germany. Methods: We identified cases through German mycology networks and scientific societies, and collected anonymised clinical information via FungiScope®. Results: We identified 13 CAM cases from six tertiary referral hospitals diagnosed between March 2020 and June 2021. Twelve patients had severe or critical COVID‐19, eleven were mechanically ventilated for a median of 8 days (range 1‐27 days) before diagnosis of CAM. Eleven patients received systemic corticosteroids. Additional underlying medical conditions were reported for all but one patient, five were immunocompromised because of malignancy or organ transplantation, three were diabetic. Eleven patients developed pneumonia. Mortality was 53.8% with a median time from diagnosis of mucormycosis to death of 9 days (range 0–214 days) despite treatment with liposomal amphotericin B and/or isavuconazole in 10 of 13 cases. CAM prevalence amongst hospitalised COVID‐19 patients overall (0.67% and 0.58% in two centres) and those admitted to the intensive care unit (ICU) (1.47%, 1.78% and 0.15% in three centres) was significantly higher compared to non‐COVID‐19 patients (P <.001 for respective comparisons). Conclusion: COVID‐19‐associated mucormycosis is rare in Germany, mostly reported in patients with comorbidities and impaired immune system and severe COVID‐19 treated in the ICU with high mortality compared to mainly rhino‐orbito‐cerebral CAM in patients with mild COVID‐19 in India. Risk for CAM is higher in hospitalised COVID‐19 patients than in other patients. [ABSTRACT FROM AUTHOR]

End-stage renal disease is associated with chronic stress that in turn may result in endocrine changes, affect cognitive, and physical capacities and increase the risk for cardiovascular events. The objective of this study was to evaluate and characterize possible stress parameters and compare cognitive function in those patients. Physiological and biochemical stress parameters as well as cognitive function were assessed in 17 hemodialysis and 18 renal transplant patients and both groups were compared. Serum cortisol and interleukin-6 levels were elevated in both groups but showed no significant difference. Cholesterol and low-density lipoprotein levels were significantly higher in patients following renal transplantation. While heart rate variability was comparable in both groups, most cognitive tests showed better results in renal transplant patients. We showed that: (1) cognitive function may improve following renal transplantation; (2) standard biochemical stress parameters are not useful to discriminate stress in patients with chronic kidney disease; and (3) heart rate variability is unaltered in this setting. [ABSTRACT FROM AUTHOR]

Aims: There is a widespread perception among clinicians and pathologists that the histomorphological assessment of minor salivary gland (MinSG) tumours is more difficult and hampered by more misdiagnoses than that of major salivary gland tumours. This is based on a vague, subjective clinical impression, lacking scientific proof. The aim of the present study was to identify and statistically verify potential reasons that could explain this difference. Methods and results: We identified 14 putative clinical, pathological and combined clinicopathological reasons that, altogether, could explain the phenomenon of the perceived greater diagnostic difficulty associated with MinSG tumours. We performed a comprehensive literature search and a statistical comparison of data from a large personal consultation series (biased for difficult cases) with cumulated data from straightforward, unselected (non‐consultation) series from the literature. By performing this comparison, we identified, with statistical significance, a comprehensive series of reasons, as well as of consequences, of the greater difficulty in diagnosing MinSG tumours. Conclusions: Among the 14 criteria, high frequencies of initial incisional biopsies and of a low‐grade category in malignant tumours emerged as the two most important reasons for enhanced diagnostic difficulty. Very rare entities, unusual locations, shortcomings in clinicopathological communication, and pecularities of the special anatomical location of the hard palate, such as tumour necrosis, mucosal ulceration, pseudoinvasion, and the peculiar phenomenon of 'tumoral–mucosal fusion', contribute to further diagnostic difficulties. The awareness of these shortcomings and pitfalls enables us to provide a series of recommendations for clinicians and pathologists that might aid in assessment and reduce the rate of misdiagnosis of MinSG tumours. [ABSTRACT FROM AUTHOR]

We report on the use of a 2nd‐generation Hoveyda–Grubbs‐type catalyst immobilized inside mesoporous silica for the application in selective macro(mono)cyclization (MMC) of an α,ω‐diene under spatially confined and continuous‐flow conditions. Reactions carried out with different flow rates allow for variations in residence time; conversion and MMC selectivity can be determined for well‐defined reaction times. Analysis of the reaction mixtures obtained for different reaction times and temperatures in a single flow experiment by NMR and MALDI‐TOF‐MS allows to address confinement effects and to determine olefin metathesis pathways. These investigations revealed that ring‐chain equilibria are quickly established but substantially affected by residence time and flow, allowing for the determination of conditions under which MMC selectivity reaches a maximum. In contrast to reactions carried out in solution, in which oligomers up to the hexamer were observed, MMC under confinement predominantly proceeds via ring‐closing metathesis of the monomer and backbiting from the dimer and trimer, but not from higher oligomers as their formation is suppressed. This leads to the observed high MMC selectivity, reaching 60 % at a 25 mM substrate concentration. [ABSTRACT FROM AUTHOR]

The tides in the Kitikmeot Sea, in the southern Canadian Arctic Archipelago, are found to be heavily influenced by seasonal sea‐ice formation and blocking in a strait. Data from a moored current profiler in Dease Strait exhibit strong tidal damping during wintertime seasonal sea‐ice cover, with 50%–60% reduction in tidal elevation and 65% reduction in tidal velocities. We used a 3D unstratified barotropic numerical tidal model of the region to show that the observed wintertime tidal damping likely requires both high sea‐ice friction and a partial sea‐ice blockage in Victoria Strait (VS), the eastern gateway of the Kitikmeot Sea, where tidal‐induced ridging causes thick, rough ice to accumulate over its shallow sill. Our analysis of the model shows different dynamics for the M2 and K1 tides. Both tidal constituents are dominated by the Atlantic tides entering through VS. Overall, ∼90% of the M2 tidal energy entering VS does not reach Dease Strait because, in addition to dissipation in VS (∼25%), it is significantly diverted into adjoining bays and around an amphidrome in eastern Queen Maud Gulf (∼65%). In contrast, the smaller K1 tide is less diverted into the subsidiary channels, after ∼20% dissipation in VS and only ∼25% in adjoining bays, it propagates far into the region and is amplified due to resonance in Dease Strait and Coronation Gulf, resulting in larger tidal height than the M2 tide in Coronation Gulf. Plain Language Summary: In the Canadian Arctic Archipelago tides influence the nutrient distribution, heat flux, and sea‐ice dynamics amid other processes. While most tidal models of the Arctic do not include the seasonal growth and melt of sea ice, we show that tides in the Kitikmeot Sea are greatly impacted by this. Tidal elevation and velocities from a moored current profiler in Dease Strait are damped 50%–65% during wintertime seasonal sea‐ice cover. In Victoria Strait (VS), the eastern gateway of the Kitikmeot Sea, thick, rough ice accumulates over the shallow sill. We use numerical models to show that our observed tidal damping in Dease Strait requires both large sea‐ice friction and a partial sea‐ice blockage in VS. Key Points: Tidal height and currents are damped >50% in winter, likely due to high sea‐ice friction and tidal‐induced sea‐ice blockages upstreamUpon entering the Kitikmeot Sea, the dominant Atlantic‐origin tides dissipate, resulting in relatively low tidal energyThe K1 tidal height is larger than the M2 tidal height in the western Kitikmeot Sea due to tidal resonance [ABSTRACT FROM AUTHOR]

We present the δ18O isotope composition of 16 multi‐year ice (MYI) and eight first‐year ice (FYI) cores collected during spring from the Lincoln Sea, a region within the Last Ice Area, which is expected to retain MYI longest into the future. Isotopic signatures were used to quantify the contribution of snow to sea ice mass. These estimates yield a higher total snow contribution in MYI (10 ± 5%) than to FYI (4 ± 2%). Converted to Snow Depth Equivalent (SDE), MYI had five times larger SDE (0.79 ± 0.38 m) than FYI (0.16 ± 0.11 m). The difference is explained by the contribution of refrozen surface and under‐ice melt ponds as well as superimposed/interposed ice for MYI resulting from higher accumulation of snow over multiple, longer accumulation seasons compared to FYI. Given the impending replacement of MYI by FYI, the large difference in absolute snow contributions between MYI and FYI highlights the potential implications in terms of the redistribution of precipitation‐derived (meteoric) freshwater throughout the Arctic Ocean. Furthermore, we observed high relative snow contributions to ice mass in the surface of one‐third of older FYI cores, which we attributed to flooding and formation of snow‐ice. Our results support the premise that flooding events on FYI may be more prevalent throughout the Arctic Ocean than previously assumed. Plain Language Summary: Snow is important for the Arctic energy balance, ongoing climate change, and the disappearance of the sea ice. Snow acts like a blanket on the ice keeping the sea ice warmer in the winter by preventing heat loss into the cold atmosphere above. While in summer, snow can also insulate the ice from warm air temperatures delaying the start of ice melt. Snow can also be incorporated into the ice and contribute to the Arctic sea ice mass balance. How much of the Arctic ice is made up of refrozen snow is largely unknown. Our results indicate that the older, multi‐year ice has a larger snow contribution to ice mass than younger first‐year ice. This difference arises as the older ice accumulates more snow‐melt water into its mass each melt season, which means that when the older ice melts it releases freshwater, accumulated over several years, far away from where it picked it up. The younger Arctic sea ice releases snow it has accumulated already in the first summer closer to the snow fall location. As a result of the disappearing older sea ice, the distance snow‐melt water is transported across the Arctic will likely decrease. Key Points: Multi‐year ice (MYI) had five times larger snow depth equivalent contributions to ice mass compared to first‐year ice (FYI)Reductions in MYI will impact the redistribution of precipitation‐derived freshwater throughout the Arctic OceanFlooding on FYI may be more prevalent in the Arctic Ocean than previously assumed [ABSTRACT FROM AUTHOR]

Using airborne measurements, we provide a first direct glimpse of the sea ice thickness distribution in the western Ross Sea, Antarctica, where the distinguishing sea ice process is the regular occurrence of the Ross Sea, McMurdo Sound, and Terra Nova Bay polynyas. Two flights in November 2017 over a length of 800 km reveal a heavily deformed ice regime with a mean thickness of 2.0 ± 1.6 m. Supported by satellite image analysis, we identify regional variability in ice thickness based on formation history. Sea ice thickness gradients are highest within 100 and 200 km of the Terra Nova Bay and McMurdo Sound polynyas, respectively, where the mean thickness of the thickest 10% of ice is 7.6 m. Overall, about 80% of the ice is heavily deformed, concentrated in ridges with thicknesses of 3.0–11.8 m. This is evidence that sea ice is much thicker than in the central Ross Sea. Plain Language Summary: Antarctic sea ice is a stabilizing factor for global climate but has an unknown mass trend as thickness is particularly hard to measure. The western Ross Sea is an important region of sea ice formation; here, persistent off‐shore winds form so called coastal polynyas enabling continued freezing by pushing new ice out into the pack ice zone. Using a specialized instrument on a fixed wing aircraft, we measured in this region a mean sea ice thickness of 2 m over a distance of 800 km, which is much thicker than measured in the central Ross Sea. Making use of high‐resolution satellite images and aerial photos, we found that narrow deformational ridges grow up to 16 m in thickness and more rapidly than level ice. Such deformed ice holds up to 80% of the ice mass, which is quite easily overlooked by satellite sensors. Our observations hold a link between wind driven ice dynamics and the ice mass exported from the western Ross Sea, which with this new thickness data could be higher than previously thought. Providing this information, we establish a basis for change detection and the evaluation of computer simulations of Antarctic sea ice in a changing climate. Key Points: Airborne measurements of sea ice thickness in the Western Ross Sea reveal strongly deformed ice with a mean of 2.0 and a maximum of 15.6 mTime series of satellite images show evolution and deformation history of polynya‐derived pack ice along a total survey length of 800 kmSea ice thickness gradients are highest within 100–200 km of polynyas, where the mean thickness of the thickest 10% of ice is 7.6 m [ABSTRACT FROM AUTHOR]

During the 2018 Multidisciplinary Arctic Program‐Last Ice in the Lincoln Sea, we sampled 45 multiyear ice (MYI) and 34 first‐year ice (FYI) cores, combined with snow depth, ice thickness, and transmittance surveys from adjacent level FYI and undeformed MYI. FYI sites show a decoupling between bottom‐ice chlorophyll a (chl a) and snow depth; however, MYI showed a significant correlation between ice‐algal chl a biomass and snow depth. Topographic control of the snow cover resulted in greater spatiotemporal variability of the snow over the level FYI, and consequently transmittance, compared to MYI with an undulating surface. The coupled patterns of snow depth, transmittance, and chl a indicate that MYI provides an environment with more stable light conditions for ice algal growth. The importance of sea ice surface topography for ice algal habitat underpins the potential ecological changes associated with projected increased ice dynamics and deformation. Plain Language Summary: This study presents first results from the 2018 Multidisciplinary Arctic Program‐Last Ice, the most intensive ecologically focused research project ever conducted within the so‐called "Last Ice Area." This region is of key importance because it is the only place in the Arctic expected to retain summer sea ice by the year 2050. Continued changes to the sea ice environment will have ecological consequences because sea ice is an important habitat for many animals from microscopic ice algae, the base of the food chain, to seals and polar bears. Since the older ice is being replaced by younger ice, we compared older ice to younger ice in order to provide a glimpse into the future. We found that the older ice has a more stable light environment for ice algae due to snow depth patterns associated with surface topography. This can mean that as the older ice is replaced by newer ice, the availability of ice algae as a food source may become more unpredictable. The importance of surface topography for ice algae indicates that the projected acceleration in sea ice drift and increased ridging due to thinner ice will likely have an impact on key sea ice habitat properties. Key Points: Spatiotemporal changes in snow cover and transmittance were observed for FYI but remained stable for MYI due to differences in topographyThe spatial distribution of bottom‐ice chl a biomass was coupled to snow depth and transmittance in MYI but decoupled in FYIA projected shift to a more dynamic and deformed sea ice cover is likely to be a key driver of ice‐algal habitat variability in the future [ABSTRACT FROM AUTHOR]

We combine Eulerian ice draft observations from moored ice‐profiling sonars with buoy‐ and satellite‐derived ice drift data to obtain Lagrangian observations of changes in the thickness distribution of sea ice circulating the Beaufort Sea. We examine repeat measurements of ice draft by identifying events where buoys or pseudobuoys made repeat overpasses within 30 km of ice‐profiling sonar‐equipped Beaufort Gyre Exploration Project moorings. Comparison of ice draft distributions from each overpass indicates that summertime melt rates are related to drift track, with more melt occurring in the southern Beaufort Sea than to the north. Additionally, we find that ice surviving summer in the Beaufort Sea since 2007 is similar in thickness to surrounding first‐year sea ice by the end of the following winter. These findings are supported by continuous ice thickness data from ice mass balance buoys. By examining "plumes" of pseudobuoys originating at each mooring location, we identify anomalous northward transport of ice in the southern Beaufort Sea in 2007 that likely contributed to the record‐breaking reduction in sea ice extent that year. We also find that repeat overpasses have been much rarer since 2007, due to reduced summertime sea ice extent in the Beaufort Gyre and possible changes in ice drift patterns. These changes contribute to diminished replenishment of multiyear sea ice volume in the Arctic. Plain Language Summary: Using ice motion data from buoys and satellites, we track sea ice as it circulates in the Beaufort Gyre and measure changes in its thickness as it passes over moored upward looking sonars. Our results show that ice drifting through the southern Beaufort Sea in summer experiences significant thinning and that multiyear ice surviving the summer does not grow much thicker than first‐year ice even after multiple winters. We also find that the northward retreat of the summertime ice edge in Beaufort Sea is leading to a reduced likelihood of ice recirculating and growing older and thicker in the Beaufort Gyre. Together, these changes make any recovery of the Arctic ice pack increasingly unlikely. Key Points: Sea ice in the Beaufort Gyre is tracked as it drifts over upward looking sonars to derive Lagrangian changes in its thickness distributionSea ice traversing the Beaufort Sea south of ~75°N experiences significantly greater melt since 2007 than ice to the northBy the end of winter, perennial ice surviving summer in the Beaufort Gyre is similar in thickness to first‐year ice grown in just one season [ABSTRACT FROM AUTHOR]

The optimization of complex chemical reaction systems is often a troublesome and time‐consuming process. The application of modern technologies, including automated reactors and analytics, opens the avenue for generating large data sets on chemical reaction processes in a short period of time. In this work, an automated flow reactor is used to present detailed kinetics and mechanistic studies about an amine‐catalyzed Knoevenagel−Michael domino reaction to yield tetrahydrochromene derivatives. High‐performance monoliths as catalyst supports and online coupled HPLC analysis allow for time‐efficient data generation. We show that the two‐step multicomponent domino reaction does not follow the kinetics of consecutive reaction steps proceeding independently from each other. Instead, the starting materials of both individual reactions compete for the active sites on the heterogeneous catalyst, which lowers the rate constants of both steps. This knowledge was used to implement a more efficient experimental setup which increased the turnover numbers of the catalyst, without adjusting common reaction parameters like temperature, reaction time, and concentrations. [ABSTRACT FROM AUTHOR]

To better understand recent changes of Arctic sea ice thickness and extent, it is important to distinguish between the contributions of winter growth and summer melt to the sea ice mass balance. In this study we present a Lagrangian approach to quantify summer sea ice melt in which multiyear ice (MYI) floes that were surveyed by airborne electromagnetic thickness sounding within Nares Strait during summer were backtracked, using satellite imagery, to a region in close proximity (3–20 km) to spring ice thickness surveys carried out in the Lincoln Sea. Typical modal total MYI thicknesses, including ~0.4‐m snow, ranged between 3.9 and 4.7 m in the Lincoln Sea during April. Ice‐only modal thicknesses were between 2.2 and 3.0 m in Nares Strait during August. Total thinning including snow and ice was 1.3 ± 0.1 m including 0.4 ± 0.09 m of snow melt and 0.9 ± 0.2 m of ice melt. This translates to a seasonal net heat input of 305 ± 69 MJ/m2 (262 ± 60 MJ/m2 for ice only) and seasonal net heat flux of 57 ± 13 W/m2 (45 ± 10 W/m2 for ice only), which is unlikely to be explained by solar radiation fluxes alone. Furthermore, our approach provides an improvement on traditional ice mass balance buoy estimates because it integrates melt over larger spatial scales, where melt can be highly variable due to differential melt experienced between melt ponds, bare ice, hummocks, and ridges. Plain Language Summary: Some of the oldest and thickest sea ice remains in a small region between Canada, Greenland and the North Pole, the so‐called "Last Ice Area", and will retain this ice longest into the future. Thus, continued monitoring of this unique sea ice habitat is crucial in order to document ongoing changes in the physical environment and to better predict the fate of many animals that depend on sea ice for survival (e.g., polar bears and seals). In this study, we compared sea ice thickness measurements from spring and summer to provide a better understanding of how the ice changes from season to season. Ice thickness changes provide important information on the Arctic Ocean's energy budget, a good indicator of the health of the Arctic Ocean. Our measurements are particularly important because they are the first of their kind over old, thick ice during summer in this unique region. We showed that 0.9 m of old sea ice melted from spring to summer. Although this is comparable to previous studies of old ice, it is important to continue these measurements in order document the expected ongoing changes to the sea ice environment and monitor the health of the Arctic Ocean. Key Points: MYI surveyed in the Lincoln Sea during spring had modal thicknesses of 3.9‐4.7 m, which thinned to 2.2‐3.0 m in summer in Nares StraitBacktracking individual floes with satellite images was used to reconstruct positions of the same ice fields surveyed in spring and summerEstimated sea ice melt was 0.9 +/‐ 0.2 m, slightly higher than observations by ice mass balance buoys for the same region [ABSTRACT FROM AUTHOR]

Abstract: Spring melt pond fraction (fp) has been shown to influence September sea ice extent and, with a growing need to improve melt pond physics in climate and forecast models, observations at large spatial scales are needed. We present a novel technique for estimating fp on sea ice at high spatial resolution from the Sentinel‐1 satellite during the winter period leading up to spring melt. A strong correlation (r = −0.85) is found between winter radar backscatter and fp from first‐year and multiyear sea ice data collected in the Canadian Arctic Archipelago (CAA) in 2015. Observations made in the CAA in 2016 are used to validate a fp retrieval algorithm, and a fp prediction for the CAA in 2017 is made. The method is effective using the horizontal transmit and receive polarization channel only and shows promise for providing seasonal, pan‐Arctic, fp maps for improved understanding of melt pond distributions and forecast model skill. [ABSTRACT FROM AUTHOR]

River system measurement and mapping using UAVs is both lean and agile, with the added advantage of increased safety for the surveying crew. A common parameter of fluvial geomorphological studies is the flow velocity, which is a major driver of sediment behavior. Advances in fluid mechanics now include metrics describing the presence and interaction of coherent structures within a flow field and along its boundaries. These metrics have proven to be useful in studying the complex turbulent flows but require time-resolved flow field data, which is normally unavailable in geomorphological studies. Contactless UAV-based velocity measurement provides a new source of velocity field data for measurements of extreme hydrological events at a safe distance, and could allow for measurements of inaccessible areas. Recent works have successfully applied large-scale particle image velocimetry (LSPIV) using UAVs in rivers, focusing predominantly on surficial flow estimation by tracking intensity differences between georeferenced images. The objective of this work is to introduce a methodology for UAV based real-time particle tracking in rivers (RAPTOR) in a case study along a short test reach of the Brigach River in the German Black Forest. This methodology allows for large-scale particle tracking velocimetry (LSPTV) using a combination of floating, infrared light-emitting particles and a programmable embedded color vision sensor in order to simultaneously detect and track the positions of objects. The main advantage of this approach is its ability to rapidly collect and process the position data, which can be done in real time. The disadvantages are that the method requires the use of specialized light-emitting particles, which in some cases cannot be retrieved from the investigation area, and that the method returns velocity data in unscaled units of px/s. This work introduces the RAPTOR system with its hardware, data processing workflow, and provides an example of unscaled velocity field estimation using the proposed method. First experiences with the method show that the tracking rate of 50 Hz allows for position estimation with sub-pixel accuracy, even considering UAV self-motion. A comparison of the unscaled tracks after Savitzky-Golay filtering shows that although the time-averaged velocities remain virtually the same, the filter reduces the standard deviation by more than 40% and the maxima by 20%. Copyright © 2017 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

There is mounting evidence that multiyear ice ( MYI) is a unique component of the Arctic Ocean and may play a more important ecological role than previously assumed. This study improves our understanding of the potential of MYI as a suitable habitat for sea ice algae on a pan-Arctic scale. We sampled sea ice cores from MYI and first-year sea ice ( FYI) within the Lincoln Sea during four consecutive spring seasons. This included four MYI hummocks with a mean chl a biomass of 2.0 mg/m2, a value significantly higher than FYI and MYI refrozen ponds. Our results support the hypothesis that MYI hummocks can host substantial ice-algal biomass and represent a reliable ice-algal habitat due to the (quasi-) permanent low-snow surface of these features. We identified an ice-algal habitat threshold value for calculated light transmittance of 0.014%. Ice classes and coverage of suitable ice-algal habitat were determined from snow and ice surveys. These ice classes and associated coverage of suitable habitat were applied to pan-Arctic CryoSat-2 snow and ice thickness data products. This habitat classification accounted for the variability of the snow and ice properties and showed an areal coverage of suitable ice-algal habitat within the MYI-covered region of 0.54 million km2 (8.5% of total ice area). This is 27 times greater than the areal coverage of 0.02 million km2 (0.3% of total ice area) determined using the conventional block-model classification, which assigns single-parameter values to each grid cell and does not account for subgrid cell variability. This emphasizes the importance of accounting for variable snow and ice conditions in all sea ice studies. Furthermore, our results indicate the loss of MYI will also mean the loss of reliable ice-algal habitat during spring when food is sparse and many organisms depend on ice-algae. [ABSTRACT FROM AUTHOR]

State-of-the-art Arctic Ocean mean sea surface (MSS) models and global geoid models (GGMs) are used to support sea ice freeboard estimation from satellite altimeters, as well as in oceanographic studies such as mapping sea level anomalies and mean dynamic ocean topography. However, errors in a given model in the high-frequency domain, primarily due to unresolved gravity features, can result in errors in the estimated along-track freeboard. These errors are exacerbated in areas with a sparse lead distribution in consolidated ice pack conditions. Additionally model errors can impact ocean geostrophic currents, derived from satellite altimeter data, while remaining biases in these models may impact longer-term, multisensor oceanographic time series of sea level change in the Arctic. This study focuses on an assessment of five state-of-the-art Arctic MSS models (UCL13/04 and DTU15/13/10) and a commonly used GGM (EGM2008). We describe errors due to unresolved gravity features, intersatellite biases, and remaining satellite orbit errors, and their impact on the derivation of sea ice freeboard. The latest MSS models, incorporating CryoSat-2 sea surface height measurements, show improved definition of gravity features, such as the Gakkel Ridge. The standard deviation between models ranges 0.03-0.25 m. The impact of remaining MSS/GGM errors on freeboard retrieval can reach several decimeters in parts of the Arctic. While the maximum observed freeboard difference found in the central Arctic was 0.59 m (UCL13 MSS minus EGM2008 GGM), the standard deviation in freeboard differences is 0.03-0.06 m. [ABSTRACT FROM AUTHOR]

In April 2017, we collected unique, extensive in situ data of sea ice and snow thickness. At 10 sampling sites, located under a CryoSat-2 overpass, between Ellesmere Island and 87.1°N mean and modal total ice thicknesses ranged between 2 to 3.4 m and 1.8 to 2.9 m, respectively. Coincident snow thicknesses ranged between 0.3 to 0.47 m (mean) and 0.1 to 0.5 m (mode). The profile spanned the complete multiyear ice zone in the Lincoln Sea, into the first-year ice zone farther north. Complementary snow thickness measurements near the North Pole showed a mean thickness of 0.31 m. Compared with scarce measurements from other years, multiyear ice was up to 0.75 m thinner than in 2004, but not significantly different from 2011 and 2014. We found excellent agreement with a commonly used snow climatology and with published long-term ice thinning rates. There was reasonable agreement with CryoSat-2 thickness retrievals. [ABSTRACT FROM AUTHOR]

Snow thickness on sea ice is a largely undersampled parameter yet of importance for the sea ice mass balance and for satellite-based sea ice thickness estimates and thus our general understanding of global ice volume change. Traditional direct thickness measurements with meter sticks can provide accurate but only spot information, referred to as 'needles' due to their pinpoint focus and information, while airborne and satellite remote sensing snow products, referred to as 'the haystack,' have large uncertainties due to their scale. We demonstrate the remarkable accuracy and applicability of ground-penetrating radar (GPR) snow thickness measurements by comparing them with in situ meter stick data from two field campaigns to Antarctica in late winter/early spring. The efficiency and millimeter-to-centimeter accuracy of GPR enables practitioners to acquire extensive, semiregional data with the potential to upscale needles to the haystack and to potentially calibrate satellite remote sensing products that we confirm to derive roughly 30% of the in situ thickness. We find the radar wave propagation velocity in snow to be rather constant (± 6%), encouraging regional snow thickness surveys. Snow thinner than 10 cm is under the detection limit with the off-the-shelf GPR setup utilized in our study. [ABSTRACT FROM AUTHOR]

Objective To examine the possibility that CXCL16 recruits endothelial cells (ECs) to developing neovasculature in rheumatoid arthritis (RA) synovium. Methods We utilized the RA synovial tissue SCID mouse chimera system to examine human microvascular EC (HMVEC) and human endothelial progenitor cell (EPC) recruitment into engrafted human synovium that was injected intragraft with CXCL16-immunodepleted RA synovial fluid (SF). CXCR6-deficient and wild-type (WT) C57BL/6 mice were primed to develop K/BxN serum-induced arthritis and evaluated for angiogenesis. HMVECs and EPCs from human cord blood were also examined for CXCR6 expression, by immunofluorescence and assessment of CXCL16 signaling activity. Results CXCR6 was prominently expressed on human EPCs and HMVECs, and its expression on HMVECs could be up-regulated by interleukin-1β. SCID mice injected with CXCL16-depleted RA SF exhibited a significant reduction in EPC recruitment. In experiments using the K/BxN serum-induced inflammatory arthritis model, CXCR6−/− mice showed profound reductions in hemoglobin levels, which correlated with reductions in monocyte and T cell recruitment to arthritic joint tissue compared to that observed in WT mice. Additionally, HMVECs and EPCs responded to CXCL16 stimulation, but exhibited unique signal transduction pathways and homing properties. Conclusion These results indicate that CXCL16 and its receptor CXCR6 may be a central ligand/receptor pair that is closely associated with EPC recruitment and blood vessel formation in the RA joint. [ABSTRACT FROM AUTHOR]

Objective Hyperkalaemia is a common feature in hospitalized patients and often attributed to drugs antagonizing the renin-angiotensin-aldosterone system ( RAAS) and/or acute kidney injury ( AKI), despite significantly preserved glomerular filtration rate ( GFR). The objective of this study was to determine the prevalence and role of renal tubular acidosis type IV ( RTA IV) in the development of significant hyperkalaemia. Design A single-centre retrospective study. Patients Patients admitted to a University Hospital over 12 months. Measurements Patients with a potassium value > 6·0 m m were identified. Clinical and laboratory data were revisited, and patients with a normal anion gap metabolic acidosis were evaluated for the existence of RTA IV. Results A total of 57 patients having significant hyperkalaemia (>6·0 m m) were identified. Twelve patients had end-stage renal disease, while 21 patients had solely AKI or progressive chronic renal failure. RTA IV was present in 24 patients (42%), of whom 71% had pre-existing renal insufficiency because of diabetic nephropathy or tubulointerstitial nephritis. All hyperkalaemic patients with urinary/serum electrolytes suggestive of RTA IV had evidence of AKI, but creatinine levels were significantly lower ( P < 0·05), while the number of drugs antagonizing the RAAS was comparable. Conclusion We demonstrated that RTA IV (i) is very common in patients with hyperkalaemia; (ii) should always be suspected in hyperkalaemic patients with only moderately impaired GFR; and (iii) may result in significant hyperkalaemia in the presence of both AKI and drugs antagonizing the RAAS. [ABSTRACT FROM AUTHOR]

The article considers whether soluble blood group antigens, Lewisy-6 and H, have roles in monocyte recruitment in rheumatoid arthritis. According to the author, the glucose analog of H, H-2g, has the ability to induce human monocyte migration in vitro. They reveal that H-2g increased mononuclear cell homing in vivo into an RA synovial tissue-SCID mouse chimera model. They conclude that the glucose analog may be a novel mediator of monocyte recruitment in inflammatory diseases.

The article presents a study which aimed to use a gene therapy approach to examine the role of interleukin-13 (IL-13) in angiogenesis in vivo, using a rat adjuvant-induced arthritis model of rheumatoid arthritis (RA). In the study, ankle joints of female rats were injected preventatively with an adenovirus vector containing human IL-13 (AxCAIL-13), a control vector with no insert (AxCANI) or phosphate buffered saline (PBS). Results of the study showed AxCAIL-13-treated joint homogenates had lower hemoglobin levels, suggesting reduced joint vascularity.

The article focuses on a study which investigated the hypothesis that endothelial progenitor cells (EPCs) selectively home to inflamed joint tissue and may perpetuate synovial neovascularization. The neovascularization and EPC accumulation in mouse ankle synovium was measured using a collagen-induced arthritis (CIA) model. It was found that cells bearing EPC markers were significantly increased in peripheral blood and accumulated in inflamed synovial pannus, in mice with CIA.

Aims In contrast to cyclosporin, only limited information exists on the interaction potential between the immunosuppressive agent tacrolimus and HMG-CoA reduc-tase inhibitors, which are metabolized via the cytochrome P450 system. The aim of this study was to investigate the pharmacokinetics, and adverse effects of cerivastatin combined with tacrolimus in renal transplant patients. Methods Ten patients with stable kidney graft functions and LDL-cholesterol serum concentrations >110 mg dl[SUP-1] were included in the study. After an observation period of 3 months, cerivastatin (0.2 mg daily) was administered for an additional 3 months. Tacrolimus steady-state pharmacokinetics and cerivastatin single- and multiple-dose pharmacokinetics were determined. Lipid concentrations, routine laboratory parameters and adverse events were obtained and analysed throughout the study period of 6 months. Results Blood tacrolimus trough concentrations were not affected by cerivastatin (mean± SD 8.6± 2.1 ng ml[SUP-1] before, and 8.7± 2.4 ng ml[SUP-1] at day 90 of cerivastatin dosing, with a 95% confidence interval on the difference = 0.97, 1.08). The mean area under the blood concentration-time curve to 24 h (AUC[SUB(0,24 h])) for cerivastatin was 14.5± 2.53μg l[SUP-1]h[SUP-1] at day 1 after starting treatment and 19.02± 3.55mg l[SUP-1] h[SUP-1] (3 months later), resulting in a 35% higher (AUC[SUP(0,24 h)]) compared with the)first dose. Total cholesterol, LDL-cholesterol and triglyceride concentrations were significantly lowered by cerivastatin whereas no significant effect of cerivastatin on serum creatininkinase concentrations was observed and no adverse effects were documented. Conclusions Tacrolimus increased the AUC[SUB(0, 24 h)] of cerivastatin by a mean of 35% in renal transplant patients. Cerivastatin had no detectable effect on the pharmaco-kinetics of tacrolimus. [ABSTRACT FROM AUTHOR]

Following ectodomain shedding, Notch-1 undergoes presenilin (PS)-dependent constitutive intramembranous endoproteolysis at site-3. This cleavage is similar to the PS-dependent γ-secretase cleavage of the β-amyloid precursor protein (βAPP). However, topological differences in cleavage resulting in amyloid β-peptide (Aβ) or the Notch-1 intracellular domain (NICD) indicated independent mechanisms of proteolytic cleavage. We now demonstrate the secretion of an N-terminal Notch-1 Aβ-like fragment (Nβ). Analysis of Nβ by MALDI-TOF MS revealed that Nβ is cleaved at a novel site (site-4, S4) near the middle of the transmembrane domain. Like the corresponding cleavage of βAPP at position 40 and 42 of the Aβ domain, S4 cleavage is PS dependent. The precision of this cleavage is affected by familial Alzheimer's disease-associated PS1 mutations similar to the pathological endoproteolysis of βAPP. Considering these similarities between intramembranous processing of Notch and βAPP, we conclude that these proteins are cleaved by a common mechanism utilizing the same protease, i.e. PS/γ-secretase. [ABSTRACT FROM AUTHOR]

Examines molecular evidences for stages of tuberculosis in ancient bone samples in Hungary. Use of osseous tissue specimens; Amplification of the IS6110 sequence; Importance of polymerase chain reaction for recognizing DNA segments of different mycobacterial species; Significance of DNA primers with 65-kDa antigen gene.