Build-up and decline of organic matter during PeECE III

Increasing atmospheric carbon dioxide (CO2) concentrations due to anthropogenic fossil fuel combustion are currently changing the ocean's chemistry. Increasing oceanic [CO2] and consequently decreasing seawater pH have the potential to significantly impact marine life. Here we describe and analyze the build-up and decline of a natural phytoplankton bloom initiated during the 2005 mesocosm Pelagic Ecosystem CO2 Enrichment study (PeECE III). The draw-down of inorganic nutrients in the upper surface layer of the mesocosms was reflected by a concomitant increase of organic matter until day t11, the peak of the bloom. From then on, biomass standing stocks steadily decreased as more and more particulate organic matter was lost into the deeper layer of the mesocosms. We show that organic carbon export to the deeper layer was significantly enhanced at elevated CO2. This phenomenon might have impacted organic matter remineralization leading to decreased oxygen concentrations in the deeper layer of the high CO2 mesocosms as indicated by deep water ammonium concentrations. This would have important implications for our understanding of pelagic ecosystem functioning and future carbon cycling

High export of dissolved silica from the Greenland Ice Sheet

Silica is an essential element for marine life and plays a key role in the biogeochemistry of the ocean. Glacial activity stimulates rock weathering, generating dissolved silica that is exported to coastal areas along with meltwater. The magnitude of the dissolved silica export from large glacial areas such as the Greenland Ice Sheet is presently poorly quantified and not accounted for in global budgets. Here we present data from two fjord systems adjacent to the Greenland Ice Sheet which reveal a large export of dissolved silica by glacial meltwater relative to other macronutrients. Upscaled to the entire Greenland Ice Sheet, the export of dissolved silica equals 22 ± 10 Gmol Si yr−1. When the silicate-rich meltwater mixes with upwelled deep water, either inside or outside Greenland's fjords, primary production takes place at increased silicate to nitrate ratios. This likely stimulates the growth of diatoms relative to other phytoplankton groups

Blood volume measurement with indocyanine green pulse spectrophotometry: dose and site of dye administration

(1) To determine the optimal administration site and dose of indocyanine green (ICG) for blood volume measurement using pulse spectrophotometry, (2) to assess the variation in repeated blood volume measurements for patients after subarachnoid hemorrhage and (3) to evaluate the safety and efficacy of this technique in patients who were treated for an intracranial aneurysm. Four repeated measurements of blood volume (BV) were performed in random order of bolus dose (10 mg or 25 mg ICG) and venous administration site (peripheral or central) in eight patients admitted for treatment of an intracranial aneurysm. Another five patients with subarachnoid hemorrhage underwent three repeated BV measurements with 25 mg ICG at the same administration site to assess the coefficient of variation. The mean +/- SD in BV was 4.38 +/- 0.88 l (n = 25) and 4.69 +/- 1.11 l (n = 26) for 10 mg and 25 mg ICG, respectively. The mean +/- SD in BV was 4.59 +/- 1.15 l (n = 26) and 4.48 +/- 0.86 l (n = 25) for central and peripheral administration, respectively. No significant difference was found. The coefficient of variance of BV measurement with 25 mg of ICG was 7.5% (95% CI: 3-12%). There is no significant difference between intravenous administration of either 10 or 25 mg ICG, and this can be injected through either a peripheral or central venous catheter. The 7.5% coefficient of variation in BV measurements determines the detectable differences using ICG pulse spectrophotometr

The Relationship between Phytoplankton Distribution and Water Column Characteristics in North West European Shelf Sea Waters

Phytoplankton underpin the marine food web in shelf seas, with some species having properties that are harmful to human health and coastal aquaculture. Pressures such as climate change and anthropogenic nutrient input are hypothesized to influence phytoplankton community composition and distribution. Yet the primary environmental drivers in shelf seas are poorly understood. To begin to address this in North Western European waters, the phytoplankton community composition was assessed in light of measured physical and chemical drivers during the “Ellett Line” cruise of autumn 2001 across the Scottish Continental shelf and into adjacent open Atlantic waters. Spatial variability existed in both phytoplankton and environmental conditions, with clear differences not only between on and off shelf stations but also between different on shelf locations. Temperature/salinity plots demonstrated different water masses existed in the region. In turn, principal component analysis (PCA), of the measured environmental conditions (temperature, salinity, water density and inorganic nutrient concentrations) clearly discriminated between shelf and oceanic stations on the basis of DIN∶DSi ratio that was correlated with both salinity and temperature. Discrimination between shelf stations was also related to this ratio, but also the concentration of DIN and DSi. The phytoplankton community was diatom dominated, with multidimensional scaling (MDS) demonstrating spatial variability in its composition. Redundancy analysis (RDA) was used to investigate the link between environment and the phytoplankton community. This demonstrated a significant relationship between community composition and water mass as indexed by salinity (whole community), and both salinity and DIN∶DSi (diatoms alone). Diatoms of the Pseudo-nitzschia seriata group occurred at densities potentially harmful to shellfish aquaculture, with the potential for toxicity being elevated by the likelihood of DSi limitation of growth at most stations and depths

Altered Immune Responses in Rhesus Macaques Co-Infected with SIV and Plasmodium cynomolgi: An Animal Model for Coincident AIDS and Relapsing Malaria

BACKGROUND:Dual epidemics of the malaria parasite Plasmodium and HIV-1 in sub-Saharan Africa and Asia present a significant risk for co-infection in these overlapping endemic regions. Recent studies of HIV/Plasmodium falciparum co-infection have reported significant interactions of these pathogens, including more rapid CD4+ T cell loss, increased viral load, increased immunosuppression, and increased episodes of clinical malaria. Here, we describe a novel rhesus macaque model for co-infection that supports and expands upon findings in human co-infection studies and can be used to identify interactions between these two pathogens. METHODOLOGY/PRINCIPAL FINDINGS:Five rhesus macaques were infected with P. cynomolgi and, following three parasite relapses, with SIV. Compared to macaques infected with SIV alone, co-infected animals had, as a group, decreased survival time and more rapid declines in markers for SIV progression, including peripheral CD4+ T cells and CD4+/CD8+ T cell ratios. The naïve CD4+ T cell pool of the co-infected animals was depleted more rapidly than animals infected with SIV alone. The co-infected animals also failed to generate proliferative responses to parasitemia by CD4+ and CD8+ T cells as well as B cells while also having a less robust anti-parasite and altered anti-SIV antibody response. CONCLUSIONS/SIGNIFICANCE:These data suggest that infection with both SIV and Plasmodium enhances SIV-induced disease progression and impairs the anti-Plasmodium immune response. These data support findings in HIV/Plasmodium co-infection studies. This animal model can be used to further define impacts of lentivirus and Plasmodium co-infection and guide public health and therapeutic interventions

Will ocean acidification affect marine microbes?

Author Posting. © The Author(s), 2010. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in The ISME Journal 5 (2011): 1-7, doi:10.1038/ismej.2010.79.The pH of the surface ocean is changing as a result of increases in atmospheric carbon dioxide (CO2) and there are concerns about potential impacts of lower pH and associated alterations in seawater carbonate chemistry on the biogeochemical processes in the ocean. However, it is important to place these changes within the context of pH in the present day ocean, which is not constant; it varies systematically with season, depth and along productivity gradients. Yet this natural variability in pH has rarely been considered in assessments of the effect of ocean acidification on marine microbes. Surface pH can change as a consequence of microbial utilisation and production of carbon dioxide, and to a lesser extent other microbiallymediated processes such as nitrification. Useful comparisons can be made with microbes in other aquatic environments that readily accommodate very large and rapid pH change. For example, in many freshwater lakes, pH changes that are orders of magnitude greater than those projected for the 22nd century oceans can occur over periods of hours. Marine and freshwater assemblages have always experienced variable pH conditions. Therefore, an appropriate null hypothesis may be, until evidence is obtained to the contrary, that major biogeochemical processes in the oceans other than calcification will not be fundamentally different under future higher CO2 / lower pH conditions.Funding from the Gordon and Betty Moore Foundation, and logistical support from the Plymouth Marine Laboratory and the Center for Microbial Oceanography: Research and Education (National Science Foundation grant EF-0424599) are gratefully acknowledged

Cost-effectiveness of external cephalic version for term breech presentation

<p>Abstract</p> <p>Background</p> <p>External cephalic version (ECV) is recommended by the American College of Obstetricians and Gynecologists to convert a breech fetus to vertex position and reduce the need for cesarean delivery. The goal of this study was to determine the incremental cost-effectiveness ratio, from society's perspective, of ECV compared to scheduled cesarean for term breech presentation.</p> <p>Methods</p> <p>A computer-based decision model (TreeAge Pro 2008, Tree Age Software, Inc.) was developed for a hypothetical base case parturient presenting with a term singleton breech fetus with no contraindications for vaginal delivery. The model incorporated actual hospital costs (e.g., $8,023 for cesarean and$5,581 for vaginal delivery), utilities to quantify health-related quality of life, and probabilities based on analysis of published literature of successful ECV trial, spontaneous reversion, mode of delivery, and need for unanticipated emergency cesarean delivery. The primary endpoint was the incremental cost-effectiveness ratio in dollars per quality-adjusted year of life gained. A threshold of $50,000 per quality-adjusted life-years (QALY) was used to determine cost-effectiveness.</p> <p>Results</p> <p>The incremental cost-effectiveness of ECV, assuming a baseline 58$7,900/QALY. If the estimated probability of successful ECV is less than 32%, then ECV costs more to society and has poorer QALYs for the patient. However, as the probability of successful ECV was between 32% and 63%, ECV cost more than cesarean delivery but with greater associated QALY such that the cost-effectiveness ratio was less than $50,000/QALY. If the probability of successful ECV was greater than 63%, the computer modeling indicated that a trial of ECV is less costly and with better QALYs than a scheduled cesarean. The cost-effectiveness of a trial of ECV is most sensitive to its probability of success, and not to the probabilities of a cesarean after ECV, spontaneous reversion to breech, successful second ECV trial, or adverse outcome from emergency cesarean.</p> <p>Conclusions</p> <p>From society's perspective, ECV trial is cost-effective when compared to a scheduled cesarean for breech presentation provided the probability of successful ECV is > 32%. Improved algorithms are needed to more precisely estimate the likelihood that a patient will have a successful ECV.</p

Branched Chain Fatty Acids Reduce the Incidence of Necrotizing Enterocolitis and Alter Gastrointestinal Microbial Ecology in a Neonatal Rat Model

Branched chain fatty acids (BCFA) are found in the normal term human newborn's gut, deposited as major components of vernix caseosa ingested during late fetal life. We tested the hypothesis that premature infants' lack of exposure to gastrointestinal (GI) BCFA is associated with their microbiota and risk for necrotizing enterocolitis (NEC) using a neonatal rat model.Pups were collected one day before scheduled birth. The pups were exposed to asphyxia and cold stress to induce NEC. Pups were assigned to one of three experimental treatments. DF (dam-fed); Control, hand-fed rat milk substitute; BCFA, hand-fed rat milk substitute with 20%w/w BCFA. Total fat was equivalent (11%wt) for both the Control and BCFA groups. Cecal microbiota were characterized by 16S rRNA gene pyrosequencing, and intestinal injury, ileal cytokine and mucin gene expression, interleukin-10 (IL-10) peptide immunohistochemistry, and BCFA uptake in ileum phospholipids, serum and liver were assessed.NEC incidence was reduced by over 50% in the BCFA group compared to the Control group as assessed in ileal tissue; microbiota differed among all groups. BCFA-fed pups harbored greater levels of BCFA-associated Bacillus subtilis and Pseudomonas aeruginosa compared to Controls. Bacillus subtilis levels were five-fold greater in healthy pups compared to pups with NEC. BCFA were selectively incorporated into ileal phospholipids, serum and liver tissue. IL-10 expression increased three-fold in the BCFA group versus Controls and no other inflammatory or mucosal mRNA markers changed.At constant dietary fat level, BCFA reduce NEC incidence and alter microbiota composition. BCFA are also incorporated into pup ileum where they are associated with enhanced IL-10 and may exert other specific effects

Identification of surface proteins in Enterococcus faecalis V583

<p>Abstract</p> <p>Background</p> <p>Surface proteins are a key to a deeper understanding of the behaviour of Gram-positive bacteria interacting with the human gastro-intestinal tract. Such proteins contribute to cell wall synthesis and maintenance and are important for interactions between the bacterial cell and the human host. Since they are exposed and may play roles in pathogenicity, surface proteins are interesting targets for drug design.</p> <p>Results</p> <p>Using methods based on proteolytic "shaving" of bacterial cells and subsequent mass spectrometry-based protein identification, we have identified surface-located proteins in <it>Enterococcus faecalis </it>V583. In total 69 unique proteins were identified, few of which have been identified and characterized previously. 33 of these proteins are predicted to be cytoplasmic, whereas the other 36 are predicted to have surface locations (31) or to be secreted (5). Lipid-anchored proteins were the most dominant among the identified surface proteins. The seemingly most abundant surface proteins included a membrane protein with a potentially shedded extracellular sulfatase domain that could act on the sulfate groups in mucin and a lipid-anchored fumarate reductase that could contribute to generation of reactive oxygen species.</p> <p>Conclusions</p> <p>The present proteome analysis gives an experimental impression of the protein landscape on the cell surface of the pathogenic bacterium <it>E. faecalis</it>. The 36 identified secreted (5) and surface (31) proteins included several proteins involved in cell wall synthesis, pheromone-regulated processes, and transport of solutes, as well as proteins with unknown function. These proteins stand out as interesting targets for further investigation of the interaction between <it>E. faecalis </it>and its environment.</p