Chromium isotopes in marine hydrothermal sediments

Hydrothermal chromium (Cr) cycling contributes to marine Cr inventories and their Cr isotopic composition, yet Cr isotope effects associated with this cycling remain poorly documented. Here we determine the distribution, isotopic composition, and diagenetic mobility of Cr in hydrothermal sediments from the distal flank of the South East Pacific Rise (SEPR, DSDP-site 598). We find that Cr is primarily associated with the metalliferous iron (oxyhydr) oxide and detrital components of the sediment (0.4–3.6 mg kg⁻¹), whereas Cr concentrations are much lower in the dominant carbonate phase (80% Cr from the sediment relative to Fe. We propose this loss is tied to oxidation of authigenic Cr(III) to Cr(VI) followed by diagenetic remobilization and efflux from the sediment pile. The bulk δ⁵³Cr composition of the SEPR sediments is isotopically light (−0.24 to −0.57 ± 0.05‰) and the authigenic δ⁵³Cr is as light as −1.2 ± 0.2‰, and we argue that this light Cr isotopic composition results from the partial reduction of oxic seawater-bearing Cr(VI) by reduced hydrothermal vent fluids enriched in Fe(II)aq. Diagenetic oxidation of the reactive Cr pool by Mn-oxides and loss of Cr(VI) from the sediment may further deplete the sediment in ⁵³Cr during diagenesis. The δ⁵³Cr composition of the detrital Cr fraction of the sediment (average δ⁵³Cr composition = −0.05 ± 0.04‰) falls within the igneous silicate earth (ISE) range, revealing that detrital Cr delivered to this region of the Pacific ocean is unfractionated, and has carried a relatively constant δ⁵³Cr composition over the last 5.7 million years. Together our results show that light δ⁵³Cr compositions in hydrothermal sediments are imparted through a combination of processes previously overlooked in the marine Cr biogeochemical cycle, and that the δ⁵³Cr composition of such sediments may provide a rich source of information on paleo-marine redox conditions

“Without a mother”: caregivers and community members’ views about the impacts of maternal mortality on families in KwaZulu-Natal, South Africa.

BACKGROUND: Maternal mortality in South Africa is high and a cause for concern especially because the bulk of deaths from maternal causes are preventable. One of the proposed reasons for persistently high maternal mortality is HIV which causes death both indirectly and directly. While there is some evidence for the impact of maternal death on children and families in South Africa, few studies have explored the impacts of maternal mortality on the well-being of the surviving infants, older children and family. This study provides qualitative insight into the consequences of maternal mortality for child and family well-being throughout the life-course. METHODS: This qualitative study was conducted in rural and peri-urban communities in Vulindlela, KwaZulu-Natal. The sample included 22 families directly affected by maternal mortality, 15 community stakeholders and 7 community focus group discussions. These provided unique and diverse perspectives about the causes, experiences and impacts of maternal mortality. RESULTS AND DISCUSSION: Children left behind were primarily cared for by female family members, even where a father was alive and involved. The financial burden for care and children’s basic needs were largely met through government grants (direct and indirectly targeted at children) and/or through an obligation for the father or his family to assist. The repercussions of losing a mother were felt more by older children for whom it was harder for caregivers to provide educational supervision and emotional or psychological support. Respondents expressed concerns about adolescent’s educational attainment, general behaviour and particularly girl’s sexual risk. CONCLUSION: These results illuminate the high costs to surviving children and their families of failing to reduce maternal mortality in South Africa. Ensuring social protection and community support is important for remaining children and families. Additional qualitative evidence is needed to explore differential effects for children by gender and to guide future research and inform policies and programs aimed at supporting maternal orphans and other vulnerable children throughout their development.Web of Scienc

Seasonal variations in the nitrogen isotopic composition of settling particles at station K2 in the western subarctic North Pacific

Intensive observations using hydrographical cruises and moored sediment trap deployments during 2010 and 2012 at station K2 in the North Pacific western subarctic gyre (WSG) revealed seasonal changes in δ15N of both suspended and settling particles. Suspended particles (SUS) were collected from depths between the surface and 200 m; settling particles by drifting traps (DST; 100-200 m) and moored traps (MST; 200 and 500 m). All particles showed higher δ15N values in winter and lower in summer, contrary to the expected by isotopic fractionation during phytoplankton nitrate consumption. We suggest that these observed isotopic patterns are due to ammonium consumption via light-controlled nitrification, which could induce variations in δ15N(SUS) of 0.4-3.1 ‰ in the euphotic zone (EZ). The δ15N(SUS) signature was reflected by δ15 N(DST) despite modifications during biogenic transformation from suspended particles in the EZ. δ15 N enrichment (average: 3.6 ‰) and the increase in C:N ratio (by 1.6) in settling particles suggests year-round contributions of metabolites from herbivorous zooplankton as well as TEPs produced by diatoms. Accordingly, seasonal δ15 N(DST) variations of 2.4-7.0 ‰ showed a significant correlation with primary productivity (PP) at K2. By applying the observed δ15 N(DST) vs. PP regression to δ15 N(MST) of 1.9-8.0 ‰, we constructed the first annual time-series of PP changes in the WSG. Moreover, the monthly export ratio at 500 m was calculated using both estimated PP and measured organic carbon fluxes. Results suggest a 1.6 to 1.8 times more efficient transport of photosynthetically-fixed carbon to the intermediate layers occurs in summer/autumn rather than winter/spring

The use of interim data and Data Monitoring Committee recommendations in randomized controlled trial reports: frequency, implications and potential sources of bias

Background: Interim analysis of accumulating trial data is important to protect participant safety during randomized controlled trials (RCTs). Data Monitoring Committees (DMCs) often undertake such analyses, but their widening role may lead to extended use of interim analysis or recommendations that could potentially bias trial results.Methods: Systematic search of eight major publications: Annals of Internal Medicine, BMJ, Circulation, CID, JAMA, JCO, Lancet and NEJM, including all randomised controlled trials ( RCTs) between June 2000 and May 2005 to identify RCTs that reported use of interim analysis, with or without DMC involvement. Recommendations made by the DMC or based on interim analysis were identified and potential sources of bias assessed. Independent double data extraction was performed on all included trials.Results: We identified 1772 RCTs, of which 470 (27%; 470/1772) reported the use of a DMC and a further 116 (7%; 116/1772) trials reported some form of interim analysis without explicit mention of a DMC. There were 28 trials ( 24 with a formal DMC), randomizing a total of 79396 participants, identified as recommending changes to the trial that may have lead to biased results. In most of these, some form of sample size re-estimation was recommended with four trials also reporting changes to trial endpoints. The review relied on information reported in the primary publications and methods papers relating to the trials, higher rates of use may have occurred but not been reported.Conclusion: The reported use of interim analysis and DMCs in clinical trials has been increasing in recent years. It is reassuring that in most cases recommendations were made in the interest of participant safety. However, in practice, recommendations that may lead to potentially biased trial results are being made

Intracranial injection of dengue virus induces interferon stimulated genes and CD8(+) T cell infiltration by sphingosine kinase 1 independent pathways

We have previously reported that the absence of sphingosine kinase 1 (SK1) affects both dengue virus (DENV) infection and innate immune responses in vitro. Here we aimed to define SK1-dependancy of DENV-induced disease and the associated innate responses in vivo. The lack of a reliable mouse model with a fully competent interferon response for DENV infection is a challenge, and here we use an experimental model of DENV infection in the brain of immunocompetent mice. Intracranial injection of DENV-2 into C57BL/6 mice induced body weight loss and neurological symptoms which was associated with a high level of DENV RNA in the brain. Body weight loss and DENV RNA level tended to be greater in SK1-/- compared with wildtype (WT) mice. Brain infection with DENV-2 is associated with the induction of interferon-β (IFN-β) and IFN-stimulated gene (ISG) expression including viperin, Ifi27l2a, IRF7, and CXCL10 without any significant differences between WT and SK1-/- mice. The SK2 and sphingosine-1-phosphate (S1P) levels in the brain were unchanged by DENV infection or the lack of SK1. Histological analysis demonstrated the presence of a cellular infiltrate in DENV-infected brain with a significant increase in mRNA for CD8 but not CD4 suggesting this infiltrate is likely CD8+ but not CD4+ T-lymphocytes. This increase in T-cell infiltration was not affected by the lack of SK1. Overall, DENV-infection in the brain induces IFN and T-cell responses but does not influence the SK/S1P axis. In contrast to our observations in vitro, SK1 has no major influence on these responses following DENV-infection in the mouse brain.Wisam H. Al-Shujairi, Jennifer N. Clarke, Lorena T. Davies, Mohammed Alsharifi, Stuart M. Pitson, Jillian M. Car

Clinical Outcome of Veterans with Acute Coronary Syndrome Who Had Been Exposed to Agent Orange

2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), one of the components of Agent Orange, has been reported to be a deadly poison despite its presence at extremely small doses. TCDD is reported to cause various kinds of cancers and other harmful effects on humans. However, a correlation between exposure to TCDD and acute coronary syndrome (ACS) is not yet proven. Thus, we examined the correlation between exposure to TCDD and ACS through an analysis of coronary angiograms from veterans of the Vietnam War. Two hundred fifty-one consecutive men undergoing coronary angiograms owing to ACS between April 2004 and May 2009 at Gwangju Veterans Hospital were analyzed. Included subjects were between 50 and 70 years of age. The patients were divided into two groups: 121 patients who had been exposed to TCDD (Group I) and 130 patients who had not been exposed to TCDD (Group II). Clinical and coronary angiographic findings were evaluated. Baseline clinical characteristics, inflammatory markers, and echocardiographic parameters were not significantly different between the two groups. The incidence of hypertension (71.1% vs. 60.0%, p=0.039) and hyperlipidemia (27.3% vs. 16.9%, p=0.038) was higher in Group I than in Group II. Total occlusion, stent length, stent use, and coronary lesion characteristics were not significantly different between the two groups. The rate of major adverse cardiovascular events (MACE) had no relationship with exposure to TCDD. Exposure to TCDD might not affect severity or the rate of MACE in persons with ACS

Silica burial enhanced by iron limitation in oceanic upwelling margins

In large swaths of the ocean, primary production by diatoms may be limited by the availability of silica, which in turn limits the biological uptake of carbon dioxide. The burial of biogenic silica in the form of opal is the main sink of marine silicon. Opal burial occurs in equal parts in iron-limited open-ocean provinces and upwelling margins, especially the eastern Pacific upwelling zone. However, it is unclear why opal burial is so efficient in this margin. Here we measure fluxes of biogenic material, concentrations of diatom-bound iron and silicon isotope ratios using sediment traps and a sediment core from the Gulf of California upwelling margin. In the sediment trap material, we find that periods of intense upwelling are associated with transient iron limitation that results in a high export of silica relative to organic carbon. A similar correlation between enhanced silica burial and iron limitation is evident in the sediment core, which spans the past 26,000 years. A global compilation also indicates that hotspots of silicon burial in the ocean are all characterized by high silica to organic carbon export ratios, a diagnostic trait for diatoms growing under iron stress. We therefore propose that prevailing conditions of silica limitation in the ocean are largely caused by iron deficiency imposing an indirect constraint on oceanic carbon uptake

Contemporary epidemiology of hospitalised heart failure with reduced versus preserved ejection fraction in England: a retrospective, cohort study of whole-population electronic health records.

BACKGROUND: Heart failure is common, complex, and often associated with coexisting chronic medical conditions and a high mortality. We aimed to assess the epidemiology of people admitted to hospital with heart failure with reduced ejection fraction (HFrEF) and heart failure with preserved ejection fraction (HFpEF), including the period covering the COVID-19 pandemic, which was previously not well characterised. METHODS: In this retrospective, cohort study, we used whole-population electronic health records with 57 million individuals in England to identify patients hospitalised with heart failure as the primary diagnosis in any consultant episode of an in-patient admission to a National Health Service (NHS) hospital. We excluded individuals with less than 1 year of medical history records in primary or secondary care; admissions to NHS hospitals for which less than 10% of heart failure cases were linkable to the National Heart Failure Audit (NHFA); individuals younger than 18 years at the time of the heart failure hospitalisation; and patients who died in hospital during the index heart failure admission. For patients with new onset heart failure, we assessed incidence rates of 30-day and 1-year all-cause and cause-specific (cardiovascular, non-cardiovascular, and heart failure-related) emergency rehospitalisation and mortality after discharge, and dispensed guideline-recommended medical therapy (GRMT). Follow-up occurred from the index admission to the earliest occurrence of the event of interest, death, or end of data coverage. We estimated adjusted hazard ratios (HRs) to compare HFrEF with HFpEF. We computed population-attributable fractions to quantify the percentage of outcomes attributable to coexisting chronic medical conditions. FINDINGS: Among 233 320 patients identified who survived the index heart failure admission across 335 NHS hospitals between Jan 1, 2019, and Dec 31, 2022, 101 320 (43·4%) had HFrEF, 71 910 (30·8%) had HFpEF, and 60 090 (25·8%) had an unknown classification. In patients with new onset heart failure, there were reductions in all-cause 30-day (-5·2% [95% CI -7·7 to -2·6] in 2019-22) and 1-year rehospitalisation rates (-3·9% [-6·6 to -1·2]). Declining 30-day rehospitalisation rates affected patients with HFpEF (-4·8% [-9·2 to -0·2]) and HFrEF (-6·2% [-10·5 to -1·6]), although 1-year rates were not statistically significant for patients with HFpEF (-2·2% [-6·6 to 2·3] vs -5·7% [-10·6 to -0·5] for HFrEF). There were no temporal trends in incidence rates of 30-day or 1-year mortality after discharge. The rates of all-cause (HR 1·20 [1·18-1·22]) and cause-specific rehospitalisation were uniformly higher in those with HFpEF than those with HFrEF. Patients with HFpEF also had higher rates of 1-year all-cause mortality after discharge (HR 1·07 [1·05-1·09]), driven by excess risk of non-cardiovascular death (HR 1·25 [1·21-1·29]). Rates of rehospitalisation and mortality were highest in patients with coexisting chronic kidney disease, chronic obstructive pulmonary disease, dementia, and liver disease. Chronic kidney disease contributed to 6·5% (5·6-7·4) of rehospitalisations within 1 year for HFrEF and 5·0% (4·1-5·9) of rehospitalisations for HFpEF, double that of any other coexisting condition. There was swift implementation of newer GRMT, but markedly lower dispensing of these medications in patients with coexisting chronic kidney disease. INTERPRETATION: Rates of rehospitalisation in patients with heart failure in England have decreased during 2019-22. Further population health improvements could be reached through enhanced implementation of GRMT, particularly in patients with coexisting chronic kidney disease, who, despite being at high risk, remain undertreated. FUNDING: Wellcome Trust, Health Data Research UK, British Heart Foundation Data Science Centre

Core outcome measurement instruments for use in clinical and research settings for adults with post-COVID-19 condition: an international Delphi consensus study

Post-COVID-19 condition (also known as long COVID) is a new, complex, and poorly understood disorder. A core outcome set (COS) for post-COVID-19 condition in adults has been developed and agreement is now required on the most appropriate measurement instruments for these core outcomes. We conducted an international consensus study involving multidisciplinary experts and people with lived experience of long COVID. The study comprised a literature review to identify measurement instruments for the core outcomes, a three-round online modified Delphi process, and an online consensus meeting to generate a core outcome measurement set (COMS). 594 individuals from 58 countries participated. The number of potential instruments for the 12 core outcomes was reduced from 319 to 19. Consensus was reached for inclusion of the modified Medical Research Council Dyspnoea Scale for respiratory outcomes. Measures for two relevant outcomes from a previously published COS for acute COVID-19 were also included: time until death, for survival, and the Recovery Scale for COVID-19, for recovery. Instruments were suggested for consideration for the remaining nine core outcomes: fatigue or exhaustion, pain, post-exertion symptoms, work or occupational and study changes, and cardiovascular, nervous system, cognitive, mental health, and physical outcomes; however, consensus was not achieved for instruments for these outcomes. The recommended COMS and instruments for consideration provide a foundation for the evaluation of post-COVID-19 condition in adults, which should help to optimise clinical care and accelerate research worldwide. Further assessment of this COMS is warranted as new data emerge on existing and novel measurement instruments