During an experiment in the North Atlantic in June 1998, water samples were collected approximately 400 km south of Iceland inside and outside of a bloom of the coccolithophorid Emiliania huxleyi. In ...vitro dimethylsulphoniopropionate (DMSP) lyase activity (DLA) was quantified using gas chromatography and found to vary from 0.1 to 142.3 nM dimethyl sulphide (DMS) h super(-1). Inside the bloom area the majority of DLA (>74%) occurred in particles >10 mu m, indicating that E. huxleyi (5 to 7 mu m diameter) made only a minor contribution to total DLA. In surface waters, phototrophic dinoflagellates (>10 mu m) made up a high proportion of the total phytoplankton biomass ( approximately 27%) towards the end of the coccolithophorid bloom and may have been the source of most of the DLA. This was also indicated by a significant correlation (p < 0.02) between DLA and the concentration of peridinin, a pigment used as a chemotaxonomic marker for dinophytes. The data presented here are the first field measurements of DLA in a coccolithophorid bloom and suggest that even a relatively low concentration of photosynthetic dinoflagellates larger than 10 mu m (during our study 18 to 105 cells ml super(-1)) may contribute significantly to DMS production. Although dinoflagellates are recognised as an important source of particulate DMSP, recognition of their significance for DMS production in the field has previously been limited to a few observations in highly concentrated coastal and shelf blooms. Very little information exists on DLA in dinophytes and further investigations are warranted in order to improve our understanding of the biogeochemical and ecophysiological significance of DMSP lyases in this group of phytoplankton.
“Infochemicals” (information-conveying chemicals) dominate much of the underwater communication in biological systems. They influence the movement and behavior of organisms, the ecological ...interactions between and across populations, and the trophic structure of marine food webs. However, relative to their terrestrial equivalents, the wider ecological and economic importance of marine infochemicals remains understudied and a concerted, cross-disciplinary effort is needed to reveal the full potential of marine chemical ecology. We highlight current challenges with specific examples and suggest how research on the chemical ecology of marine organisms could provide opportunities for implementing new management solutions for future “blue growth” (the sustainable use of ocean resources) and maintaining healthy marine ecosystems.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NMLJ, NUK, OILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
We compare dissolved dimethyl sulphide (DMS) measurements made by our independent laboratories during a mesocosm study of marine phytoplankton under different CO2 regimes in a Norwegian fjord. Sample ...preparation and analyses were conducted using headspace solid-phase microextraction (SPME) with gas chromatography-mass spectrometry (Max-Planck Institute for Chemistry, MPIC), and purge-and-trap extraction (P&T) with gas chromatography and flame photometric detection (University of East Anglia, UEA). The two analytical systems were calibrated independently. During the evolution of the bloom (22 days) DMS concentrations ranged from 1–35 nM and 90 pairs of data were available for comparison. We found a small systematic difference between the two methods, with UEA measuring on average 8% more DMS than MPIC. Overall, there was good correlation between the datasets (r2=0.997, P=0.01), with higher correlation for concentrations greater than 5 nM (r2=0.998, P=0.01) and increased scatter at lower concentrations (r2=0.833, P=0.01). We discuss potential reasons for the differences between the measurements and address the treatment of natural samples for DMS analysis. We recommend SPME be considered for wider use and encourage full analytical comparisons in the low concentration range.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
The production of dimethyl sulfide (DMS) is poorly quantified in tropical reef environments but forms an essential process that couples marine and terrestrial sulfur cycles and affects climate. Here ...we quantified net aqueous DMS production and the concentration of its cellular precursor dimethylsulfoniopropionate (DMSP) in the sea anemone Aiptasia sp., a model organism to study coral-related processes. Bleached anemones did not show net DMS production whereas symbiotic anemones produced DMS concentrations (mean ± standard error) of 160.7 ± 44.22 nmol g−1 dry weight (DW) after 48 h incubation. Symbiotic and bleached individuals showed DMSP concentrations of 32.7 ± 6.00 and 0.6 ± 0.19 µmol g−1 DW, respectively. We applied these findings to a Monte Carlo simulation to demonstrate that net aqueous DMS production accounts for only 20 % of gross aqueous DMS production. Monte Carlo-based estimations of sea-to-air fluxes of gaseous DMS showed that reefs may release 0.1 to 26.3 µmol DMS m−2 coral surface area (CSA) d−1 into the atmosphere with 40 % probability for rates between 0.5 and 1.5 µmol m−2 CSA d−1. These predictions were in agreement with directly quantified fluxes in previous studies. Conversion to a flux normalised to sea surface area (SSA) (range 0.1 to 17.4, with the highest probability for 0.3 to 1.0 µmol DMS m−2 SSA d−1) suggests that coral reefs emit gaseous DMS at lower rates than the average global oceanic DMS flux of 4.6 µmol m−2 SSA d−1 (19.6 Tg sulfur per year). The large difference between simulated gross and quantified net aqueous DMS production in corals suggests that the current and future potential for its production in tropical reefs is critically governed by DMS consumption processes. Hence, more research is required to assess the sensitivity of DMS-consumption pathways to ongoing environmental change in order to address the impact of predicted degradation of coral reefs on DMS production in tropical coastal ecosystems and its impact on future atmospheric DMS concentrations and climate.
Hyperon production in the threshold region was studied in the reaction pp→K+Λp using the time-of-flight spectrometer COSY-TOF. Exclusive data, covering the full phase-space, were taken at three ...different beam momenta pbeam=2.59, 2.68 and 2.85 GeV/c (corresponding to excess energies of ɛ=85, 115 and 171 MeV). Total cross-sections were deduced to be 7.4±0.5 μb, 8.6±0.6 μb and 16.5±0.4 μb, respectively. Differential observables including Dalitz plots were obtained. From the investigation of the Dalitz plot at pbeam=2.85 GeV/c a dominant contribution of the N∗(1650)-resonance to the reaction mechanism was found. In addition the pΛ-final-state interaction turned out to have a significant influence on the Dalitz plot distribution even 171 MeV above threshold.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Objective:
To review the efficacy and safety of peramivir, an unapproved neuraminidase inhibitor recently granted an Emergency Use Authorization (EUA) by the Food and Drug Administration (FDA) for ...the treatment of 2009 H1N1 influenza in select patients.
Data Sources:
Literature was accessed via MEDLINE (1950–April 2010) using the search terms peramivir, BCX-1812, RWJ 270201, influenza H1N1, swine influenza, and neuraminidase inhibitors. The manufacturer of peramivir, BioCryst Pharmaceuticals, was contacted for unpublished data and information presented at recent scientific meetings. Information was obtained from the Centers for Disease Control and Prevention (CDC) and FDA Web sites. The mandatory requirements for the EUA for peramivir were also consulted.
Study Selection and Data Extraction:
Available English-language literature was reviewed and selected based on relevance, as was information from the CDC, FDA, and the drug manufacturer.
Data Synthesis:
The 2009 H1N1 influenza pandemic has necessitated the selective use of intravenous peramivir, an unapproved neuraminidase inhibitor. Intravenous peramivir has been studied in 4 clinical trials, 2 of which compared the drug to oseltamivir. Dose adjustments are required in pediatric patients and in those with impaired renal function. Clinicians wishing to use peramivir must request authorization from the CDC to confirm patient characteristics warranting its use and to verify the prescriber's understanding of dosing considerations and unapproved status.
Conclusions:
Peramivir has shown efficacy for the treatment of 2009 H1N1 influenza; however, it has yet to receive FDA approval. Peramivir is used in hospitalized adult and pediatric patients with suspected or laboratory-confirmed 2009 H1N1 influenza meeting specific criteria, including those unable to receive inhaled or oral neuraminidase inhibitors, those who have not responded to other neuraminidase inhibitors, or when drug delivery by a route other than intravenous is not feasible.
Full text
Available for:
NUK, OILJ, SAZU, UKNU, UL, UM, UPUK
Preeclampsia increases the risk for future chronic kidney disease (CKD). Among those diagnosed with CKD, it is unclear whether a prior history of preeclampsia, or other complications in pregnancy, ...negatively impact kidney disease progression. In this longitudinal analysis, we assessed kidney disease progression among women with glomerular disease with and without a history of a complicated pregnancy.
Adult women enrolled in the Cure Glomerulonephropathy study (CureGN) were classified based on a history of a complicated pregnancy (defined by presence of worsening kidney function, proteinuria, or blood pressure; or a diagnosis of preeclampsia, eclampsia, or hemolysis, elevated liver enzymes, and low platelets HELLP syndrome), pregnancy without these complications, or no pregnancy history at CureGN enrollment. Linear mixed models were used to assess estimated glomerular filtration rate (eGFR) trajectories and urine protein-to-creatinine ratios (UPCRs) from enrollment.
Over a median follow-up period of 36 months, the adjusted decline in eGFR was greater in women with a history of a complicated pregnancy compared to those with uncomplicated or no pregnancies (−1.96 −2.67, −1.26 vs. −0.80 −1.19, −0.42 and −0.64 −1.17, −0.11 ml/min per 1.73 m2 per year, P = 0.007). Proteinuria did not differ significantly over time. Among those with a complicated pregnancy history, eGFR slope did not differ by timing of first complicated pregnancy relative to glomerular disease diagnosis.
A history of complicated pregnancy was associated with greater eGFR decline in the years following glomerulonephropathy (GN) diagnosis. A detailed obstetric history may inform counseling regarding disease progression in women with glomerular disease. Continued research is necessary to better understand pathophysiologic mechanisms by which complicated pregnancies contribute to glomerular disease progression.
Display omitted
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Diabetes is the most common cause of end-stage renal disease in industrialized countries. This article describes the structural changes in early diabetic nephropathy and the relationship with renal ...functional parameters, blood pressure, and albumin excretion. The detrimental influence of sustained hyperglycemia and/or glycemic fluctuations on renal structural change has been well documented. Tight glycemic control is paramount to preventing the development, and even the regression, of renal lesions. As much of the renal injury from diabetes occurs in clinical silence before symptoms or laboratory findings of renal injury are evident, finding early markers of risk is imperative so that nephropathy can be prevented. Currently, the only clinical surrogate marker of diabetic renal injury available is microalbuminuria. However, given the reports of regression of microalbuminuria back to normoalbuminuria, the reliability of this tool as an indicator of risk has been questioned. The need for alternative, noninvasive surrogate markers is described in this report.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The contact angle of a droplet impinging upon a hot surface undergoes changes as the drop spreads and recoils. The motion of the liquid and the effect of evaporation from the edges of the drop affect ...the contact angle. The changes in the contact angle during spreading affect the spreading characteristics of the droplet upon impact. However, the models available in literature for the maximum spreading ratio (maximum spread diameter divided by the initial droplet diameter) do not include this effect. In addition, the actual area of contact of a droplet is needed in the heat transfer studies. The present work reports an experimental study conducted to characterize the contact angle variation as a function of the heater surface finish, heater material, and heater surface temperature prior to impact. It is seen that the dynamic advancing contact angle extends beyond the equilibrium advancing and receding contact angles during the motion of the interface. Since the droplet spreading is influenced by the dynamic advancing contact angle, it is proposed to use the dynamic contact angle measurements in the available models for maximum spreading ratio. The experimental results obtained on the maximum spreading diameter indicate the validity of this approach.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
PDF
