Impact of protists on a hydrocarbon-degrading bacterial community from deep-sea Gulf of Mexico sediments: A microcosm study

In spite of significant advancements towards understanding the dynamics of petroleum hydrocarbon degrading microbial consortia, the impacts (direct or indirect via grazing activities) of bacterivorous protists remain largely unknown. Microcosm experiments were used to examine whether protistan grazing affects the petroleum hydrocarbon degradation capacity of a deep-sea sediment microbial community from an active Gulf of Mexico cold seep. Differences in n-alkane content between native sediment microcosms and those treated with inhibitors of eukaryotes were assessed by comprehensive two-dimensional gas chromatography following 30-90 day incubations and analysis of shifts in microbial community composition using small subunit ribosomal RNA gene clone libraries. More biodegradation was observed in microcosms supplemented with eukaryotic inhibitors. SSU rRNA gene clone libraries from oil-amended treatments revealed an increase in the number of proteobacterial clones (particularly γ-proteobacteria) after spiking sediments with diesel oil. Bacterial community composition shifted, and degradation rates increased, in treatments where protists were inhibited, suggesting protists affect the hydrocarbon degrading capacity of microbial communities in sediments collected at this Gulf of Mexico site

Home dialysis: conclusions from a Kidney Disease: Improving Global Outcomes (KDIGO) controversies conference

Home dialysis modalities (home hemodialysis [HD] and peritoneal dialysis [PD]) are associated with greater patient autonomy and treatment satisfaction compared with in-center modalities, yet the level of home-dialysis use worldwide is low. Reasons for limited utilization are context-dependent, informed by local resources, dialysis costs, access to healthcare, health system policies, provider bias or preferences, cultural beliefs, individual lifestyle concerns, potential care-partner time, and financial burdens. In May 2021, KDIGO (Kidney Disease: Improving Global Outcomes) convened a controversies conference on home dialysis, focusing on how modality choice and distribution are determined and strategies to expand home-dialysis use. Participants recognized that expanding use of home dialysis within a given health system requires alignment of policy, fiscal resources, organizational structure, provider incentives, and accountability. Clinical outcomes across all dialysis modalities are largely similar, but for specific clinical measures, one modality may have advantages over another. Therefore, choice among available modalities is preference-sensitive, with consideration of quality of life, life goals, clinical characteristics, family or care-partner support, and living environment. Ideally, individuals, their care-partners, and their healthcare teams will employ shared decision-making in assessing initial and subsequent kidney failure treatment options. To meet this goal, iterative, high-quality education and support for healthcare professionals, patients, and care-partners are priorities. Everyone who faces dialysis should have access to home therapy. Facilitating universal access to home dialysis and expanding utilization requires alignment of policy considerations and resources at the dialysis-center level, with clear leadership from informed and motivated clinical teams

A ground water flow model for the A/M Area of the SRS

In 1984 and 1985, a quasi three-dimensional groundwater flow model was developed for the A/M Area (Savannah River Laboratory Complex) of the Savannah River Site to assist in the design of a groundwater recovery well network to remediate groundwater contaminated with chlorinated hydrocarbon solvents. In 1986, the existing groundwater flow model was used to evaluate the effectiveness of groundwater remediation systems. Since the original model was developed, additional monitoring wells have been installed, the understanding of the hydrogeologic system has improved and the horizontal and vertical extent of the contamination in the groundwater systems has been better defined. The objective of this study is to update and improve the existing A/M Area groundwater flow model by incorporating recent hydrologic information. The new model is calibrated to 1989--1990 groundwater levels and surface water flows. The model area is approximately 31 square miles and encompasses a manufacturing and processing area designated the A/M Area, a previous waste effluent disposal basin and overflow to a natural depression (Lost Lake), and several surface water features. The simulations are run on 80386-based personal computer using the public-domain groundwater flow code MODFLOW. This calibrated coarse-grid model is a base model. Specific areas of interest can be further discritized to provide more detailed and accurate water level elevations for use in particle tracking and capture analysis. The particle tracking and capture analysis are used to evaluate the groundwater contamination capture and removal capacity of proposed recovery wells