Dipole tensor-based atomic-resolution structure determination of a nanocrystalline protein by solid-state NMR

Magic-angle spinning (MAS) solid-state NMR (SSNMR) techniques have emerged in recent years for solving complete structures of uniformly labeled proteins lacking macroscopic order. Strategies used thus far have relied primarily on semiquantitative distance restraints, analogous to the nuclear Overhauser effect (NOE) routinely used in solution NMR. Here, we present a complementary approach for using relative orientations of molecular fragments, determined from dipolar line shapes. Whereas SSNMR distance restraints typically have an uncertainty of approximately 1 A, the tensor-based experiments report on relative vector (pseudobond) angles with precision of a few degrees. By using 3D techniques of this type, vector angle (VEAN) restraints were determined for the majority of the 56-residue B1 immunoglobulin binding domain of protein G [protein GB1 (a total of 47 HN-HN, 49 HN-HC, and 12 HA-HB restraints)]. By using distance restraints alone in the structure calculations, the overall backbone root-mean-square deviation (bbRMSD) was 1.01 +/- 0.13 A (1.52 +/- 0.12 A for all heavy atoms), which improved to 0.49 +/- 0.05 A (1.19 +/- 0.07 A) on the addition of empirical chemical shift [torsion angle likelihood obtained from shift and sequence similarity (TALOS)] restraints. VEAN restraints further improved the ensemble to 0.31 +/- 0.06 A bbRMSD (1.06 +/- 0.07 A); relative to the structure with distances alone, most of the improvement remained (bbRMSD 0.64 +/- 0.09 A; 1.29 +/- 0.07 A) when TALOS restraints were removed before refinement. These results represent significant progress toward atomic-resolution protein structure determination by SSNMR, capabilities that can be applied to a large range of membrane proteins and fibrils, which are often not amenable to solution NMR or x-ray crystallography.     

Utilizing an Ingestible Biosensor to Assess Real-Time Medication Adherence

Medication adherence monitoring has relied largely on indirect measures of pill ingestion including patient self-report, pharmacy refills, electronically triggered pill bottles, and pill counts. Our objective is to describe an ingestible biosensor system comprising a radio-frequency identification (RFID)-tagged gelatin capsule. Once the capsule dissolves in the stomach, the RFID tag activates to transmit a unique signal to a relay device which transmits a time-stamped message to a cloud-based server that functions as a direct measure of medication adherence. We describe a constellation of mobile technologies that provide real-time direct measures of medication adherence. Optimizing connectivity, relay design, and interactivity with users are important in obtaining maximal acceptability. Potential concerns including gut retention of metallic components of the ingestible biosensor and drug dissolution within a gelatin capsule should be considered. An ingestible biosensor incorporated into a medication management system has the potential to improve medication compliance with real-time monitoring of ingestion and prompt early behavioral intervention. Integration of ingestible biosensors for multiple disease states may provide toxicologists with salient data early in the care of poisoned patients in the future. Further research on device design and interventions to improve adherence is needed and will shape the evolving world of medication adherence.     

Navigating systems ideas for health practice: Towards a common learning device

Systems thinking and reference to complexity science have gained currency in health sector practice and research. The extent to which such ideas might represent a mere passing fad or might more usefully be mobilized to tackle wicked problems in health systems is a concern underpinning this paper. Developing the usefulness of the systems idea requires appreciating how systems ideas are used essentially as constructs conceptually bounded by practitioners. Systems are used for purposes of understanding and engaging the reality of health issues, with the intent of transforming the reality into one that is more manageable, equitable, and sustainable. We examine some manifestations of the systems idea in health practice and the traditions of systems practice that variously make use of them. This provides a platform for proposing a systems thinking in (health) practice heuristic: a learning device supporting how different tools and methods can address “wicked problems” in health praxis. The device is built on the use of “conversation” as a metaphor to help practitioners use systems ideas in tandem with existing disciplinary and professional skills and methods. We consider how the application of the heuristic requires, and helps to develop, human characteristics of humility, empathy, and recognition of fallibility.     

Choice of resuscitative fluids and mortality in emergency department patients with sepsis

Objective

Balanced resuscitative fluids (BF) have been associated with decreased incidence of hyperchloremic metabolic acidosis in sepsis. We hypothesized that higher proportions of BF during resuscitation would thus be associated with improved mortality in Emergency Department (ED) patients with sepsis.

Three-Snip Punctoplasty Outcome Rates and Follow-Up Treatments

Purpose: To demonstrate the success rate of three-snip punctoplasty (TSP) for the treatment of punctual stenosis and to evaluate the need for additional treatment after TSP.

Methods: A retrospective chart review was conducted of all patients undergoing TSP by a single surgeon at Bascom Palmer Eye Institute from January 1, 2006 to January 1, 2010. Outcome measures include the persistence of symptomatic epiphora, the need for additional surgical interventions, and postoperative time required until complete resolution of symptoms achieved.

Results: Primary TSP resulted in an 86% success rate with resolution of symptomatic epiphora without further surgical intervention. Seven eyes (14%) required secondary TSP with or without stent placement. All 6 eyes with TSP with stent placement achieved functional success within an average of 6.8 months (stdev 6.83) from the first TSP. The one eye that was not stented during secondary TSP required a tertiary TSP with stenting and achieved functional success within the 1 month of the final procedure.

Conclusion: Primary TSP showed an 86% success rate with the resolution of tearing by an average of 1.2 months post-operatively. Membrane formation or scarring over the surgical site required an additional TSP with stenting in 14% of patients. All 50 eyes eventually achieved functional success. TSP alone as a primary procedure is a safe, relatively simple, and effective treatment of epiphora caused by punctual stenosis. Stenting should be explored as an adjunct to this procedure if primary TSP alone does not produce resolution of symptoms.     

Development of toxicity values and exposure estimates for tetrabromobisphenol A: application in a margin of exposure assessment

Tetrabromobisphenol A (TBBPA) is used in a diverse array of products to improve fire safety. The National Toxicology Program (NTP) recently completed a 2‐year bioassay for TBBPA. The objective of the present study was to develop a cancer‐based and a non‐cancer based toxicity value and to compare such to appropriate estimates of human exposure. Data from the NTP 2‐year and 13‐week studies were selected to develop candidate toxicity values. Benchmark dose modeling and subsequent evaluation of candidate values resulted in selection of an oral reference dose (RfD) of 0.6 mg kg^?1 day^?1 based on uterine hyperplasia in rats and an oral cancer slope factor (OSF) of 0.00315 per mg kg^?1 day^?1 based on an increased incidence of uterine tumors in rats. Lifetime average daily dose (LADD) estimates ranged from 2.2 E^?7 to 3.9 E^?6 mg kg^?1 day^?1 based on age‐adjusted exposures to TBBPA via breast milk consumption, dietary intake, soil/dust ingestion and drinking water ingestion in infants, young children, older children and adults. Average daily dose (ADD) estimates ranged from 3.2 E ^?7 to 8.4 E^?5 mg kg^?1 day^?1. Resulting margin of exposure (MOE) values were > 800 000 for non‐cancer endpoints and > 32 000 000 for cancer‐based endpoints. These data collectively indicate a low level of health concern associated with exposures to TBBPA based on current data. It is anticipated that the exposure estimates, along with the toxicity values described within, should be informative for understanding human health hazards associated with TBBPA. Copyright © 2015. The Authors. Journal of Applied Toxicology Published by John Wiley & Sons Ltd.