19 research outputs found
First insights into the impacts of benthic cyanobacterial mats on fish herbivory functions on a nearshore coral reef
Interspecific protection against oxidative stress:Green algae protect harmful cyanobacteria against hydrogen peroxide
Glycemic control and long-acting insulin analog utilization in patients with type 2 diabetes
Introduction: The objective was to compare glycemic control, insulin utilization, and body weight in patients with type 2 diabetes (T2D) initiated on insulin detemir (IDet) or insulin glargine (IGlar) in a real-life setting in the Netherlands. Methods: Insulin-naïve patients with T2D, starting treatment with IDet or IGlar between January 1, 2004 and June 30, 2008, were selected from the PHARMO data network. Glycemic control (hemoglobin A1c [HbA1c]), target rates (HbA1c <7%), daily insulin dose, and weight gain were analyzed comparing IDet and IGlar for patients with available HbA1c levels both at baseline and at 1-year follow-up. Analysis of all eligible patients (AEP) and a subgroup of patients without treatment changes (WOTC) in the follow-up period were adjusted for patient characteristics, propensity scores, and baseline HbA1c. Results: A total of 127 IDet users and 292 IGlar users were included in the WOTC analyses. The mean HbA1c dropped from 8.4%-8.6% at baseline to 7.4% after 1 year. Patients at HbA1c goal increased from 9% at baseline to 32% for IDet and 11% to 35% for IGlar, which was not significantly different (OR 0.75, 95% CI 0.46, 1.24). Weight gain (n=90) was less among IDet users (+0.4kg) than among IGlar users (+1.1kg), albeit not significant. The AEP analysis (252 IDet
Preparation of polymer nanocomposite materials by 'Living' radical polymerization using the raft process
Combatting cyanobacteria with hydrogen peroxide:A laboratory study on the consequences for phytoplankton community and diversity
Resilience of microbial communities after hydrogen peroxide treatment of a eutrophic lake to suppress harmful cyanobacterial blooms
Applying low concentrations of hydrogen peroxide (H(2)O(2)) to lakes is an emerging method to mitigate harmful cyanobacterial blooms. While cyanobacteria are very sensitive to H(2)O(2), little is known about the impacts of these H(2)O(2) treatments on other members of the microbial community. In this study, we investigated changes in microbial community composition during two lake treatments with low H(2)O(2) concentrations (target: 2.5 mg L(−1)) and in two series of controlled lake incubations. The results show that the H(2)O(2) treatments effectively suppressed the dominant cyanobacteria Aphanizomenon klebahnii, Dolichospermum sp. and, to a lesser extent, Planktothrix agardhii. Microbial community analysis revealed that several Proteobacteria (e.g., Alteromonadales, Pseudomonadales, Rhodobacterales) profited from the treatments, whereas some bacterial taxa declined (e.g., Verrucomicrobia). In particular, the taxa known to be resistant to oxidative stress (e.g., Rheinheimera) strongly increased in relative abundance during the first 24 h after H(2)O(2) addition, but subsequently declined again. Alpha and beta diversity showed a temporary decline but recovered within a few days, demonstrating resilience of the microbial community. The predicted functionality of the microbial community revealed a temporary increase of anti-ROS defenses and glycoside hydrolases but otherwise remained stable throughout the treatments. We conclude that the use of low concentrations of H(2)O(2) to suppress cyanobacterial blooms provides a short-term pulse disturbance but is not detrimental to lake microbial communities and their ecosystem functioning
Interspecific protection against oxidative stress: Green algae protect harmful cyanobacteria against hydrogen peroxide
Oceanographic studies have shown that heterotrophic bacteria can protect marine cyanobacteria against oxidative stress caused by hydrogen peroxide (H2O2). Could a similar interspecific protection play a role in freshwater ecosystems? In a series of laboratory experiments and two lake treatments, we demonstrate that freshwater cyanobacteria are sensitive to H2O2 but can be protected by less-sensitive species such as green algae. Our laboratory results show that green algae degrade H2O2 much faster than cyanobacteria. Consequently, the cyanobacterium Microcystis was able to survive at higher H2O2 concentrations in mixtures with the green alga Chlorella than in monoculture. Interestingly, even the lysate of destructed Chlorella was capable to protect Microcystis, indicating a two-component H2O2 degradation system in which Chlorella provided antioxidant enzymes and Microcystis the reductants. The level of interspecific protection provided to Microcystis depended on the density of Chlorella. These findings have implications for the mitigation of toxic cyanobacterial blooms, which threaten the water quality of many eutrophic lakes and reservoirs worldwide. In several lakes, H2O2 has been successfully applied to suppress cyanobacterial blooms. Our results demonstrate that high densities of green algae can interfere with these lake treatments, as they may rapidly degrade the added H2O2 and thereby protect the bloom-forming cyanobacteria
Interaction of styrene with DODAB bilayer vesicles. influence on vesicle morphology and bilayer properties
The solubilization of styrene in large unilamellar DODAB vesicles is investigated at a styrene to DODAB molar ratio of 2:1. The combination of various vesicle characterization methods allows a simultaneous look at vesicle morphology (cryo-TEM, DLS) and molecular interactions (micro-DSC, various fluorescence techniques) and gives a complete picture of the DODAB vesicles before and after the addition of styrene. Cryo-TEM and DLS results reveal that the addition of styrene does not break up the DODAB vesicles as an entity, but the peculiar angular DODAB vesicle morphology becomes smoother and the geometries tend to be more curved. The change in morphology is explained by an enhanced bilayer fluidity and the drastic depression of the phase transition temperature as determined from calorimetry and fluorescence experiments. Moreover, micro-DSC scans and fluorescence experiments with two different pyrene probes suggest a nonhomogeneous distribution and partial demixing of solute and bilayer for temperatures below ~27 C. Above this temperature, the solute appears uniformly distributed and facilitates molecular motion in the amphiphile aggregate. The diffusion coefficient for the lateral diffusion of an amphiphilic probe is then increased by a factor of 2 compared to the pure DODAB vesicles. The observed solubilization phenomena are rationalized by interactions of the solute with both the hydrocarbon part and the polar headgroup region of the bilayer