Iron Biogeochemistry in the High Latitude North Atlantic Ocean

Iron (Fe) is an essential micronutrient for marine microbial organisms, and low supply controls productivity in large parts of the world’s ocean. The high latitude North Atlantic is seasonally Fe limited, but Fe distributions and source strengths are poorly constrained. Surface ocean dissolved Fe (DFe) concentrations were low in the study region (<0.1 nM) in summer 2010, with significant perturbations during spring 2010 in the Iceland Basin as a result of an eruption of the Eyjafjallajökull volcano (up to 2.5 nM DFe near Iceland) with biogeochemical consequences. Deep water concentrations in the vicinity of the Reykjanes Ridge system were influenced by pronounced sediment resuspension, with indications for additional inputs by hydrothermal vents, with subsequent lateral transport of Fe and manganese plumes of up to 250–300 km. Particulate Fe formed the dominant pool, as evidenced by 4–17 fold higher total dissolvable Fe compared with DFe concentrations, and a dynamic exchange between the fractions appeared to buffer deep water DFe. Here we show that Fe supply associated with deep winter mixing (up to 103 nmol m−2 d−1) was at least ca. 4–10 times higher than atmospheric deposition, diffusive fluxes at the base of the summer mixed layer, and horizontal surface ocean fluxes

Stability of dissolved and soluble Fe(II) in shelf sediment pore waters and release to an oxic water column

Shelf sediments underlying temperate and oxic waters of the Celtic Sea (NW European Shelf) were found to have shallow oxygen penetrations depths from late spring to late summer (2.2–5.8 mm below seafloor) with the shallowest during/after the spring-bloom (mid-April to mid-May) when the organic carbon content was highest. Sediment porewater dissolved iron (dFe, 85%) consisted of Fe(II) and gradually increased from 0.4 to 15 μM at the sediment surface to ~100–170 µM at about 6 cm depth. During the late spring this Fe(II) was found to be mainly present as soluble Fe(II) (>85% sFe, 7 h. Iron(II) oxidation experiments in core top and bottom waters also showed removal from solution but at rates up to 5-times slower than predicted from theoretical reaction kinetics. These data imply the presence of ligands capable of complexing Fe(II) and supressing oxidation. The lower oxidation rate allows more time for the diffusion of Fe(II) from the sediments into the overlying water column. Modelling indicates significant diffusive fluxes of Fe(II) (on the order of 23–31 µmol m−2 day−1) are possible during late spring when oxygen penetration depths are shallow, and pore water Fe(II) concentrations are highest. In the water column this stabilised Fe(II) will gradually be oxidised and become part of the dFe(III) pool. Thus oxic continental shelves can supply dFe to the water column, which is enhanced during a small period of the year after phytoplankton bloom events when organic matter is transferred to the seafloor. This input is based on conservative assumptions for solute exchange (diffusion-reaction), whereas (bio)physical advection and resuspension events are likely to accelerate these solute exchanges in shelf-seas

Early identification of risk factors for refractory secondary hyperparathyroidism in patients with long-term renal replacement therapy

Background. Secondary hyperparathyroidism can complicate renal replacement therapy (RRT) in patients with end-stage renal disease. Current medical therapies often result in hypercalcaemia and fail to correct hyperparathyroidism, but might be more effective at an early stage of disease. The aim of this study was to identify prognostic factors at the start and during the first year of RRT for refractory secondary hyperparathyroidism needing parathyroidectomy (PTx) during long-term follow-up. Methods. A total of 202 consecutive patients starting RRT between August 1988 and August 1996 at our centre with at least 1 year of follow-up were included. Biochemical and treatment data at the start and during the first year of RRT were collected. Univariate and multivariate analyses were used to identify risk factors for PTx during follow-up. Results. Thirty-three patients (16%) needed PTx after 52 +/- 23 months of RRT. Need for PTx was not different between patients undergoing haemodialysis and peritoneal dialysis, but was associated with parameters reflecting calcium and phosphate control at start and after 1 year of RRT. In a Cox multivariate model, serum parathyroid hormone [relative risk (RR): 1.02 per pmol/l; P <0.001], phosphate (RR: 1.107 per 0.1 mmol/l; P = 0.002) and alkaline phosphatase (RR: 1.004 per U/l; P = 0.049) after 1 year of RRT were independently associated with increased risk for PTx. Conclusions. Failure of control of calcium-phosphate metabolism at the start of and early during RRT is strongly associated with PTx during long-term follow-up. Given the high prevalence of insufficient phosphate control, patients may benefit from aggressive correction of serum phosphate in the pre-dialysis and early dialysis period

T1 Substaging of Nonmuscle Invasive Bladder Cancer is Associated with bacillus Calmette-Guérin Failure and Improves Patient Stratification at Diagnosis

PURPOSE: Currently, markers are lacking that can identify patients with high risk nonmuscle invasive bladder cancer who will fail bacillus Calmette-Guérin treatment. Therefore, we evaluated the prognostic value of T1 substaging in patients with primary high risk nonmuscle invasive bladder cancer. MATERIALS AND METHODS: Patients with primary high risk nonmuscle invasive bladder cancer who received ≥5 bacillus Calmette-Guérin induction instillations were included. All tumors were centrally reviewed, which included T1 substaging (microinvasion vs extensive invasion of the lamina propria). T1 patients were stratified into high risk or highest risk subgroups according to major urology guidelines. Primary end point was bacillus Calmette-Guérin failure, defined as development of a high grade recurrence. Secondary end points were high grade recurrence-free survival, defined as time from primary diagnosis to biopsy-proven high grade recurrence and progression-free survival. Time-to-event analyses were used to predict survival. RESULTS: A total of 264 patients with high risk nonmuscle invasive bladder cancer had tumor invasion of the lamina propria, of which 73% were classified as extensive invasion and 27% as microinvasion. Median followup was 68 months (IQR 43-98) and bacillus Calmette-Guérin failure was more common among patients with extensive vs microinvasive tumors (41% vs 21%, p=0.002). The 3-year high grade recurrence-free survival (defined as bacillus Calmette-Guerin failure) for patients with extensive vs microinvasive tumors was 64% vs 83% (p=0.004). In multivariate analysis, T1 substaging was an independent predictor of high grade recurrence-free survival (HR 3.2, p=0.005) and progression-free survival (HR 3.0, p=0.009). Patients with highest risk/microinvasive disease have an improved progression-free survival as compared to highest risk/T1e disease (p.adj=0.038). CONCLUSIONS: T1 substaging provides important prognostic information on patients with primary high risk nonmuscle invasive bladder cancer treated with bacillus Calmette-Guérin. The risk of bacillus Calmette-Guérin failure is higher in extensive vs microinvasive tumors. Substaging of T1 high risk nonmuscle invasive bladder cancer has the potential to guide treatment decisions on bacillus Calmette-Guérin vs alternative strategies at diagnosis

Integrated criteria document radon

De engelse versie heeft rapportnummer 710401021Abstract niet beschikbaarThe document contains a critical risk-evaluation of Radon to humans and the environment. Radon is an inert gas of which the main risk is induction of lung cancer. Considering the nature of its effects and its presence only the by-products of Rn-222 are important for man in the indoor environment. In the indoor environment the average Rn-222 concentration is about 10 times higher than in the outdoor air. The average exposure to Radon in the Netherlands results in an estimated risk of 60 cases of fatal lung cancer per million people per year, of which 80% as a result of Rn-222 and 20% as a result of Rn-200. This risk is partly present by nature (the emission is determined by the soil for about 95%) and is therefore not always controlable. Without taking measures the risk will increase as a result of building new houses. By taking measures in all houses that will be built in future (increased ventilation of crawl space, sealing the ground floor) an annual decrease of the average individual risk of o.6% seems attainable. The spread of the exposure level is large and restriction of the individual risks can only be reached by organizing the problems.DGM/SSedee AGJ/Brederode LE va

Expression of tumour necrosis factor-related apoptosis-inducing ligand death receptors in sporadic and hereditary colorectal tumours:Potential targets for apoptosis induction

Tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) and antibodies against TRAIL receptors death receptor 4 (DR4) and death receptor 5 (DR5) are under investigation for cancer therapy. To study the potential application of these agents, the expression of DR4 and DR5 were studied immunohistochemically in colorectal adenomas and carcinomas from patients with sporadic disease (n = 74 and 56, respectively), familial adenomatous polyposis (FAP, n = 41 and 4, respectively) and hereditary non-polyposis colorectal cancer (HNPCC, n = 50 and 21, respectively). BAX, which is frequently mutated in tumours with high-frequency microsatellite instability (MSI-H) may play a role in sensitivity to TRAIL. Therefore, MSI-H carcinomas (n = 42, of which 27 sporadic and 15 HNPCC) were analysed for apoptotic activity, assessed by M30 immunoreactivity, and BAX mutations. Most adenomas from all three patient groups expressed DR4 and DR5. Most carcinomas expressed DR4, except for six cases, all with mucinous histology. All carcinomas, including mucinous carcinomas, showed DR5 expression. BAX mutations were found in 6/ 42 MSI-H cancers with similar apoptotic indices and expression of DR4, DR5 and TRAIL in BAX mutant and wild-type cases. Since most sporadic and hereditary colorectal neoplasms express DR4 and DR5, targeting of these receptors may be a potential prevention or treatment strategy. (c) 2005 Elsevier Ltd. All rights reserved

Determination of TP53 mutation is more relevant than microsatellite instability status for the prediction of disease-free survival in adjuvant-treated stage III colon cancer patients

Purpose Microsatellite instability (MSI), TP53 mutation, and KRAS mutation status have been reported as prognostic factors in colon cancer. Most studies, however, have included heterogeneous groups of patients with respect to cancer stage. We determined the prognostic relevance of high-frequency MSI (MSI-H), TP53 mutations, and KRAS mutations in a well-defined group of patients with stage III colon cancer (N = 391), randomly assigned for adjuvant treatment with fluorouracil-based chemotherapy. Methods Three hundred ninety-one tumor specimens were available. MSI was determined in 273 specimens, and mutation analyses of TP53 and KRAS were performed in 220 and 205 specimens, respectively. Results In a univariate analysis, MSI-H (44 of 273; 16%) was associated with a longer disease-free (DFS,- P =.038), but in a multivariate model adjusting for nodal involvement, histology, invasion, and grade of tumor, the association of MSI status with DFS did no longer reach statistical significance, though the risk estimate for microsatellite stability versus MSI-H tumors did not change much. Mutant TP53, found in 116 (53%) of 220 tumors, was associated with a shorter DFS, both in univariate (P =.009) and multivariate analyses (P =.018), whereas KRAS mutations (58 of 205; 28%) did not show any prognostic significance. Conclusion Both mutant TP53 and MSI-H seem to be prognostic indicators for disease-free survival, but only TP53 retains statistical significance after adjusting for clinical heterogeneity. Thus, in adjuvantly treated patients with stage III colon cancer, presence or absence of a TP53 mutation should be considered as a better predictor for DFS than MSI status

Characterization of hepatitis C virus (HCV) envelope diversification from acute to chronic infection within a sexually transmitted HCV cluster by using single-molecule, real-time sequencing

In contrast to other available next-generation sequencing platforms, PacBio single-molecule, real-time (SMRT) sequencing has the advantage of generating long reads albeit with a relatively higher error rate in unprocessed data. Using this platform, we longitudinally sampled and sequenced the hepatitis C virus (HCV) envelope genome region (1,680 nucleotides [nt]) from individuals belonging to a cluster of sexually transmitted cases. All five subjects were coinfected with HIV-1 and a closely related strain of HCV genotype 4d. In total, 50 samples were analyzed by using SMRT sequencing. By using 7 passes of circular consensus sequencing, the error rate was reduced to 0.37%, and the median number of sequences was 612 per sample. A further reduction of insertions was achieved by alignment against a sample-specific reference sequence. However, in vitro recombination during PCR amplification could not be excluded. Phylogenetic analysis supported close relationships among HCV sequences from the four male subjects and subsequent transmission from one subject to his female partner. Transmission was characterized by a strong genetic bottleneck. Viral genetic diversity was low during acute infection and increased upon progression to chronicity but subsequently fluctuated during chronic infection, caused by the alternate detection of distinct coexisting lineages. SMRT sequencing combines long reads with sufficient depth for many phylogenetic analyses and can therefore provide insights into within-host HCV evolutionary dynamics without the need for haplotype reconstruction using statistical algorithms

Iron Limitation Modulates Ocean Acidification Effects on Southern Ocean Phytoplankton Communities

The potential interactive effects of iron (Fe) limitation and Ocean Acidification in the Southern Ocean (SO) are largely unknown. Here we present results of a long-term incubation experiment investigating the combined effects of CO2 and Fe availability on natural phytoplankton assemblages from the Weddell Sea, Antarctica. Active Chl a fluorescence measurements revealed that we successfully cultured phytoplankton under both Fe-depleted and Fe-enriched conditions. Fe treatments had significant effects on photosynthetic efficiency (Fv/Fm; 0.3 for Fe-depleted and 0.5 for Fe-enriched conditions), non-photochemical quenching (NPQ), and relative electron transport rates (rETR). pCO2 treatments significantly affected NPQ and rETR, but had no effect on Fv/Fm. Under Fe limitation, increased pCO2 had no influence on C fixation whereas under Fe enrichment, primary production increased with increasing pCO2 levels. These CO2-dependent changes in productivity under Fe-enriched conditions were accompanied by a pronounced taxonomic shift from weakly to heavily silicified diatoms (i.e. from Pseudo-nitzschia sp. to Fragilariopsis sp.). Under Fe-depleted conditions, this functional shift was absent and thinly silicified species dominated all pCO2 treatments (Pseudo-nitzschia sp. and Synedropsis sp. for low and high pCO2, respectively). Our results suggest that Ocean Acidification could increase primary productivity and the abundance of heavily silicified, fast sinking diatoms in Fe-enriched areas, both potentially leading to a stimulation of the biological pump. Over much of the SO, however, Fe limitation could restrict this possible CO2 fertilization effect