Massive Phytoplankton Blooms Under Arctic Sea Ice Arrigo, Kevin R.; Perovich, Donald K.; Pickart, Robert S. ...
Science (American Association for the Advancement of Science),
06/2012, Letnik:
336, Številka:
6087
Journal Article
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Phytoplankton blooms over Arctic Ocean continental shelves are thought to be restricted to waters free of sea ice. Here, we document a massive phytoplankton bloom beneath fully consolidated pack ice ...far from the ice edge in the Chukchi Sea, where light transmission has increased in recent decades because of thinning ice cover and proliferation of melt ponds. The bloom was characterized by high diatom biomass and rates of growth and primary production. Evidence suggests that under-ice phytoplankton blooms may be more widespread over nutrient-rich Arctic continental shelves and that satellite-based estimates of annual primary production in these waters may be underestimated by up to 10-fold.
Ocean colour is recognised as an Essential Climate Variable (ECV) by the Global Climate Observing System (GCOS); and spectrally-resolved water-leaving radiances (or remote-sensing reflectances) in ...the visible domain, and chlorophyll-a concentration are identified as required ECV products. Time series of the products at the global scale and at high spatial resolution, derived from ocean-colour data, are key to studying the dynamics of phytoplankton at seasonal and inter-annual scales; their role in marine biogeochemistry; the global carbon cycle; the modulation of how phytoplankton distribute solar-induced heat in the upper layers of the ocean; and the response of the marine ecosystem to climate variability and change. However, generating a long time series of these products from ocean-colour data is not a trivial task: algorithms that are best suited for climate studies have to be selected from a number that are available for atmospheric correction of the satellite signal and for retrieval of chlorophyll-a concentration; since satellites have a finite life span, data from multiple sensors have to be merged to create a single time series, and any uncorrected inter-sensor biases could introduce artefacts in the series, e.g., different sensors monitor radiances at different wavebands such that producing a consistent time series of reflectances is not straightforward. Another requirement is that the products have to be validated against in situ observations. Furthermore, the uncertainties in the products have to be quantified, ideally on a pixel-by-pixel basis, to facilitate applications and interpretations that are consistent with the quality of the data. This paper outlines an approach that was adopted for generating an ocean-colour time series for climate studies, using data from the MERIS (MEdium spectral Resolution Imaging Spectrometer) sensor of the European Space Agency; the SeaWiFS (Sea-viewing Wide-Field-of-view Sensor) and MODIS-Aqua (Moderate-resolution Imaging Spectroradiometer-Aqua) sensors from the National Aeronautics and Space Administration (USA); and VIIRS (Visible and Infrared Imaging Radiometer Suite) from the National Oceanic and Atmospheric Administration (USA). The time series now covers the period from late 1997 to end of 2018. To ensure that the products meet, as well as possible, the requirements of the user community, marine-ecosystem modellers, and remote-sensing scientists were consulted at the outset on their immediate and longer-term requirements as well as on their expectations of ocean-colour data for use in climate research. Taking the user requirements into account, a series of objective criteria were established, against which available algorithms for processing ocean-colour data were evaluated and ranked. The algorithms that performed best with respect to the climate user requirements were selected to process data from the satellite sensors. Remote-sensing reflectance data from MODIS-Aqua, MERIS, and VIIRS were band-shifted to match the wavebands of SeaWiFS. Overlapping data were used to correct for mean biases between sensors at every pixel. The remote-sensing reflectance data derived from the sensors were merged, and the selected in-water algorithm was applied to the merged data to generate maps of chlorophyll concentration, inherent optical properties at SeaWiFS wavelengths, and the diffuse attenuation coefficient at 490 nm. The merged products were validated against in situ observations. The uncertainties established on the basis of comparisons with in situ data were combined with an optical classification of the remote-sensing reflectance data using a fuzzy-logic approach, and were used to generate uncertainties (root mean square difference and bias) for each product at each pixel.
The BNT162b2 mRNA (Pfizer–BioNTech) and ChAdOx1 nCoV-19 (Oxford–AstraZeneca) COVID-19 vaccines have shown high efficacy against disease in phase 3 clinical trials and are now being used in national ...vaccination programmes in the UK and several other countries. Studying the real-world effects of these vaccines is an urgent requirement. The aim of our study was to investigate the association between the mass roll-out of the first doses of these COVID-19 vaccines and hospital admissions for COVID-19.
We did a prospective cohort study using the Early Pandemic Evaluation and Enhanced Surveillance of COVID-19—EAVE II—database comprising linked vaccination, primary care, real-time reverse transcription-PCR testing, and hospital admission patient records for 5·4 million people in Scotland (about 99% of the population) registered at 940 general practices. Individuals who had previously tested positive were excluded from the analysis. A time-dependent Cox model and Poisson regression models with inverse propensity weights were fitted to estimate effectiveness against COVID-19 hospital admission (defined as 1–adjusted rate ratio) following the first dose of vaccine.
Between Dec 8, 2020, and Feb 22, 2021, a total of 1 331 993 people were vaccinated over the study period. The mean age of those vaccinated was 65·0 years (SD 16·2). The first dose of the BNT162b2 mRNA vaccine was associated with a vaccine effect of 91% (95% CI 85–94) for reduced COVID-19 hospital admission at 28–34 days post-vaccination. Vaccine effect at the same time interval for the ChAdOx1 vaccine was 88% (95% CI 75–94). Results of combined vaccine effects against hospital admission due to COVID-19 were similar when restricting the analysis to those aged 80 years and older (83%, 95% CI 72–89 at 28–34 days post-vaccination).
Mass roll-out of the first doses of the BNT162b2 mRNA and ChAdOx1 vaccines was associated with substantial reductions in the risk of hospital admission due to COVID-19 in Scotland. There remains the possibility that some of the observed effects might have been due to residual confounding.
UK Research and Innovation (Medical Research Council), Research and Innovation Industrial Strategy Challenge Fund, Health Data Research UK.
Mucosal-associated invariant T (MAIT) cells are abundant in humans and recognize bacterial ligands. Here, we demonstrate that MAIT cells are also activated during human viral infections in vivo. MAIT ...cells activation was observed during infection with dengue virus, hepatitis C virus and influenza virus. This activation-driving cytokine release and Granzyme B upregulation-is TCR-independent but dependent on IL-18 in synergy with IL-12, IL-15 and/or interferon-α/β. IL-18 levels and MAIT cell activation correlate with disease severity in acute dengue infection. Furthermore, HCV treatment with interferon-α leads to specific MAIT cell activation in vivo in parallel with an enhanced therapeutic response. Moreover, TCR-independent activation of MAIT cells leads to a reduction of HCV replication in vitro mediated by IFN-γ. Together these data demonstrate MAIT cells are activated following viral infections, and suggest a potential role in both host defence and immunopathology.
The antiepidermal growth factor receptor monoclonal antibody cetuximab has improved survival in patients with metastatic, chemotherapy-refractory, wild-type K-RAS colorectal cancer. The addition of ...brivanib, a tyrosine kinase inhibitor targeting vascular endothelial growth factor receptor and fibroblast growth factor receptor, to cetuximab has shown encouraging early clinical activity.
Patients with metastatic colorectal cancer previously treated with combination chemotherapy were randomly assigned 1:1 to receive cetuximab 400 mg/m(2) intravenous loading dose followed by weekly maintenance of 250 mg/m(2) plus either brivanib 800 mg orally daily (arm A) or placebo (arm B). The primary end point was overall survival (OS).
A total of 750 patients were randomly assigned (376 in arm A and 374 in arm B). Median OS in the intent-to-treat population was 8.8 months in arm A and 8.1 months in arm B (hazard ratio HR, 0.88; 95% CI, 0.74 to 1.03; P = .12). Median progression-free survival (PFS) was 5.0 months in arm A and 3.4 months in arm B (HR, 0.72; 95% CI, 0.62 to 0.84; P < .001). Partial responses observed (13.6% v 7.2%; P = .004) were higher in arm A. Incidence of any grade ≥ 3 adverse events was 78% in arm A and 53% in arm B. Fewer patients received ≥ 90% dose-intensity of both cetuximab (57% v 83%) and brivanib/placebo (48% v 87%) in arm A versus arm B, respectively.
Despite positive effects on PFS and objective response, cetuximab plus brivanib increased toxicity and did not significantly improve OS in patients with metastatic, chemotherapy-refractory, wild-type K-RAS colorectal cancer.
Catastrophic costs incurred by tuberculosis (TB) patients have received considerable attention, however little is known about costs and pathways to care after a negative TB evaluation.
We conducted a ...cross-sectional study of 70 patients with a negative TB evaluation at four community health centres in rural and peri-urban Uganda. Patients were traced 9 months post-evaluation using contact information from TB registers. We collected information on healthcare visits and implemented locally-validated costing questionnaires to assess the financial impact of their symptoms post-evaluation.
Of 70 participants, 57 (81%) were traced and 53 completed the survey. 31/53 (58%) surveyed participants returned to healthcare facilities post-evaluation, making a median of 2 visits each (interquartile range IQR 1-3). 11.3% (95%CI 4.3-23.0%) of surveyed patients and 16.1% (95%CI 5.5-33.7%) of those returning to healthcare facilities incurred catastrophic costs (i.e., spent >20% annual household income). Indirect costs related to lost work represented 80% (IQR 32-100%) of total participant costs.
Patients with TB symptoms who experience financial catastrophe after negative TB evaluation may represent a larger absolute number of patients than those suffering from costs due to TB. They may not be captured by existing definitions of non-TB catastrophic health expenditure.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Because HIV viral suppression is essential for optimal outcomes and prevention efforts, understanding trends and predictors is imperative to inform public health policy.
To evaluate viral suppression ...trends in people living with HIV (PLWH), including the relationship of associated factors, such as demographic characteristics and integrase strand transfer inhibitor (ISTI) use.
Longitudinal observational cohort study.
8 HIV clinics across the United States.
PLWH receiving clinical care.
To understand trends in viral suppression (≤400 copies/mL), annual viral suppression rates from 1997 to 2015 were determined. Analyses were repeated with tests limited to 1 random test per person per year and using inverse probability of censoring weights to address loss to follow-up. Joint longitudinal and survival models and linear mixed models of PLWH receiving antiretroviral therapy (ART) were used to examine associations between viral suppression or continuous viral load (VL) levels and demographic factors, substance use, adherence, and ISTI use.
Viral suppression increased from 32% in 1997 to 86% in 2015 on the basis of all tests among 31 930 PLWH. In adjusted analyses, being older (odds ratio OR, 0.76 per decade 95% CI, 0.74 to 0.78) and using an ISTI-based regimen (OR, 0.54 CI, 0.51 to 0.57) were associated with lower odds of having a detectable VL, and black race was associated with higher odds (OR, 1.68 CI, 1.57 to 1.80) (P < 0.001 for each). Similar patterns were seen with continuous VL levels; when analyses were limited to 2010 to 2015; and with adjustment for adherence, substance use, or depression.
Results are limited to PLWH receiving clinical care.
HIV viral suppression rates have improved dramatically across the United States, which is likely partially attributable to improved ART, including ISTI-based regimens. However, disparities among younger and black PLWH merit attention.
National Institutes of Health.
Climate change challenges organisms to adapt or move to track changes in environments in space and time. We used two measures of thermal shifts from analyses of global temperatures over the past 50 ...years to describe the pace of climate change that species should track: the velocity of climate change (geographic shifts of isotherms over time) and the shift in seasonal timing of temperatures. Both measures are higher in the ocean than on land at some latitudes, despite slower ocean warming. These indices give a complex mosaic of predicted range shifts and phenology changes that deviate from simple poleward migration and earlier springs or later falls. They also emphasize potential conservation concerns, because areas of high marine biodiversity often have greater velocities of climate change and seasonal shifts.
Although the success of HIV treatment programs depends on retention and viral suppression, routine program monitoring of these outcomes may be incomplete. We used data from the national electronic ...medical record (EMR) system in Zambia to enumerate a large and regionally representative cohort of patients on treatment. We traced a random sample with unknown outcomes (lost to follow-up) to document true care status and HIV RNA levels.
On 31 July 2015, we selected facilities from 4 provinces in 12 joint strata defined by facility type and province with probability proportional to size. In each facility, we enumerated adults with at least 1 clinical encounter after treatment initiation in the previous 24 months. From this cohort, we identified lost-to-follow-up patients (defined as 90 or more days late for their last appointment), selected a random sample, and intensively reviewed their records and traced them via phone calls and in-person visits in the community. In 1 of 4 provinces, we also collected dried blood spots (DBSs) for plasma HIV RNA testing. We used inverse probability weights to incorporate sampling outcomes into Aalen-Johansen and Cox proportional hazards regression to estimate retention and viremia. We used a bias analysis approach to correct for the known inaccuracy of plasma HIV RNA levels obtained from DBSs. From a total of 64 facilities with 165,464 adults on ART, we selected 32 facilities with 104,966 patients, of whom 17,602 (17%) were lost to follow-up: Those lost to follow-up had median age 36 years, 60% were female (N = 11,241), they had median enrollment CD4 count of 220 cells/μl, and 38% had WHO stage 1 clinical disease (N = 10,690). We traced 2,892 (16%) and found updated outcomes for 2,163 (75%): 412 (19%) had died, 836 (39%) were alive and in care at their original clinic, 457 (21%) had transferred to a new clinic, 255 (12%) were alive and out of care, and 203 (9%) were alive but we were unable to determine care status. Estimates using data from the EMR only suggested that 42.7% (95% CI 38.0%-47.1%) of new ART starters and 72.3% (95% CI 71.8%-73.0%) of all ART users were retained at 2 years. After incorporating updated data through tracing, we found that 77.3% (95% CI 70.5%-84.0%) of new initiates and 91.2% (95% CI 90.5%-91.8%) of all ART users were retained (at original clinic or transferred), indicating that routine program data underestimated retention in care markedly. In Lusaka Province, HIV RNA levels greater than or equal to 1,000 copies/ml were present in 18.1% (95% CI 14.0%-22.3%) of patients in care, 71.3% (95% CI 58.2%-84.4%) of lost patients, and 24.7% (95% CI 21.0%-29.3%). The main study limitations were imperfect response rates and the use of self-reported care status.
In this region of Zambia, routine program data underestimated retention, and the point prevalence of unsuppressed HIV RNA was high when lost patients were accounted for. Viremia was prevalent among patients who unofficially transferred: Sustained engagement remains a challenge among HIV patients in Zambia, and targeted sampling is an effective strategy to identify such gaps in the care cascade and monitor programmatic progress.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Background.
We investigated whether a brief geriatric assessment (GA) would identify important patient deficits that could affect treatment tolerance and care outcomes within a sample of older cancer ...patients rated as functionally normal (80%–100%) on the Karnofsky performance status (KPS) scale.
Methods.
Cancer patients aged ≥65 years were assessed using a brief GA that included both professionally and patient‐scored KPS and measures of comorbidity, polypharmacy, cognition, function, nutrition, and psychosocial status. Data were analyzed using descriptive statistics and multivariable logistic regression.
Results.
The sample included 984 patients: mean age was 73 years (range: 65–99 years), 74% were female, and 89% were white. GA was conducted before (23%), during (41%), or after (36%) treatment. Overall, 54% had a breast cancer diagnosis (n = 528), and 46% (n = 456) had cancers at other sites. Moreover, 81% of participants (n = 796) had both professionally and self‐rated KPS ≥80, defined as functionally normal, and those patients are the focus of analysis. In this subsample, 550 (69%) had at least 1 GA‐identified deficit, 222 (28%) had 1 deficit, 140 (18%) had 2 deficits, and 188 (24%) had ≥3 deficits. Specifically, 43% reported taking ≥9 medications daily, 28% had decreased social activity, 25% had ≥4 comorbidities, 23% had ≥1 impairment in instrumental activities of daily living, 18% had a Timed Up and Go time ≥14 seconds, 18% had ≥5% unintentional weight loss, and 12% had a Mental Health Index score ≤76.
Conclusion.
Within this sample of older cancer patients who were rated as functionally normal by KPS, GA identified important deficits that could affect treatment tolerance and outcomes.
This study shows that a brief, mostly patient‐administered geriatric assessment (GA) can identify deficits that could affect treatment tolerance and outcomes in older cancer patients assessed as functionally normal by Karnofsky performance status. A brief GA should be incorporated into routine oncology practice for timely identification of patient deficits that may be remediable before or during treatment.
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