Search

TRAAK and TREK2 are two-pore domain K(+) (K2P) channels and modulated by diverse factors including temperature, membrane stretching, and lipids, such as phosphatidic acid. In addition, copper and zinc, both of which are essential for life, are known to regulate TREK2 and a number of other ion channels. However, the role of ions in the association of lipids with integral membrane proteins is poorly understood. Here, we discover cupric ions selectively modulate the binding of phosphatidylserine (PS) to TRAAK but not TREK2. Other divalent cations (Ca(2+), Mg(2+), and Zn(2+)) bind both channels but have no impact on binding PS and other lipids. Additionally, TRAAK binds more avidly to Cu(2+) and Zn(2+) than TREK2. In the presence of Cu(2+), TRAAK binds similarly to PS with different acyl chains, indicating a crucial role of the serine headgroup in coordinating Cu(2+). High-resolution native mass spectrometry (MS) enables the determination of equilibrium binding constants for distinct Cu(2+)-bound stoichiometries and uncovered the highest coupling factor corresponds to a 1:1 PS-to-Cu(2+) ratio. Interestingly, the next three highest coupling factors had a ~1.5:1 PS-to-Cu(2+) ratio. Our findings bring forth the role of cupric ions as an essential cofactor in selective TRAAK-PS interactions.

Integral membrane proteins are embedded in the biological membrane, where they carry out numerous biological processes. Although lipids present in the membrane are crucial for membrane protein function, it remains difficult to characterize many lipid binding events to membrane proteins, such as those that form the annular belt. Here, we use native mass spectrometry along with the charge-reducing properties of trimethylamine

The cost-effectiveness and reliability of waste collection services in informal settlements can be difficult to optimize given the geospatial and temporal variability of latrine use. Daily servicing to avoid overflow events is inefficient, but dynamic scheduling of latrine servicing could reduce costs by providing just-in-time servicing for latrines. This study used cellular-connected motion sensors and machine learning to dynamically predict when daily latrine servicing could be skipped with a low risk of overflow. Sensors monitored daily latrine activity, and enumerators collected solid and liquid waste weight data. Given the complex relationship between latrine use and the need for servicing, an ensemble machine learning algorithm (Super Learner) was used to estimate waste weights and predict overflow events to facilitate dynamic scheduling. Accuracy of waste weight predictions based on sensor and historical weight data was adequate for estimating latrine fill levels (mean error of 20% and 22% for solid and liquid wastes), but there was greater accuracy in predicting overflow events (area under the receiver operating characteristic curve of 0.90). Although our simulations indicate that dynamic scheduling could substantially reduce costs for lower use latrines, we found that cost reduction was more modest for higher use latrines and that there was a significant gap between the simulated and implemented results.

Increasing frequency and severity of drought is driving increased use of groundwater resources in arid regions of Northern Kenya, where approximately 2.5 million people depend on groundwater for personal use, livestock, and limited irrigation. As part of a broader effort to provide more sustainable water, sanitation, and hygiene services in the region, we have collected data related to site functionality and use for approximately 120 motorized boreholes across five counties. Using a multilevel model to account for geospatial and temporal clustering, we found that borehole sites, which counties had identified as strategic assets during drought, ran on average about 1.31 h less per day compared to non-strategic borehole sites. As this finding was contrary to our hypothesis that strategic boreholes would exhibit greater use on average compared to non-strategic boreholes, we consider possible explanations for this discrepancy. We also use a coupled human and natural systems framework to explore how policies and program activities in a complex system depend on consistent and reliable feedback mechanisms. Funding was provided by the United States Agency for International Development. The views expressed in this article do not necessarily reflect the views of the United States Agency for International Development or the United States Government.

Access to oral health care continues to be a problem in the United States. Research has called for innovative approaches to improve access to oral health care and reduce oral health care disparities. Successful alternate approaches have been reported. In 1998 the Kansas Legislature passed a proposal to enhance access to care and manpower needs by allowing dental assistants to provide supragingival scaling, a service traditionally assigned to dental hygienists. In 2000, Mitchell et al. investigated the perceptions of Kansas dental hygienists and scaling dental assistants in relation to House Bill 2724 (HB 2724), which allows dental assistants to perform coronal scaling. The intent of the study was to collect baseline data in relation to HB 2724. The purpose of the present study was to follow up on the impact of HB 2724 six years after legislation. Both groups report satisfaction with their professions: scaling dental assistants believe the delivery of care in Kansas has changed, and areas of Kansas previously noted as dental health professional shortage areas are now served by either a registered dental hygienist or scaling dental assistant.