The structure of NAD+ consuming protein Acinetobacter baumannii TIR domain shows unique kinetics and conformations.

Toll-like and interleukin-1/18 receptor/resistance (TIR) domain-containing proteins function as important signaling and immune regulatory molecules. TIR domain-containing proteins identified in eukaryotic and prokaryotic species also exhibit NAD+ hydrolase activity in select bacteria, plants, and mammalian cells. We report the crystal structure of the Acinetobacter baumannii TIR domain protein (AbTir-TIR) with confirmed NAD+ hydrolysis and map the conformational effects of its interaction with NAD+ using hydrogen-deuterium exchange-mass spectrometry. NAD+ results in mild decreases in deuterium uptake at the dimeric interface. In addition, AbTir-TIR exhibits EX1 kinetics indicative of large cooperative conformational changes, which are slowed down upon substrate binding. Additionally, we have developed label-free imaging using the minimally invasive spectroscopic method 2-photon excitation with fluorescence lifetime imaging, which shows differences in bacteria expressing native and mutant NAD+ hydrolase-inactivated AbTir-TIRE208A protein. Our observations are consistent with substrate-induced conformational changes reported in other TIR model systems with NAD+ hydrolase activity. These studies provide further insight into bacterial TIR protein mechanisms and their varying roles in biology.

Toward safe hospital discharge: a transitions in care curriculum for medical students.

BACKGROUND: Medical errors often occur when patients move between care settings. Physicians generally receive little formal education on improving patient care transitions. OBJECTIVE: To develop a sustainable and effective Transition in Care Curriculum (TICC). Specific goals were to increase student confidence in and knowledge of skills necessary during care transitions at the time of hospital discharge, and to quantify the frequency of student-identified medication discrepancies during a post-discharge home visit. DESIGN: TICC was delivered to 136 3rd-year medical students during their required inpatient medicine clerkship at six urban Denver hospitals. TICC consists of small and large group interactive sessions and self-directed learning exercises to provide foundational knowledge of care transitions. Experiential learning occurs through direct patient care at the time of discharge and during a follow-up home, hospice, or skilled nursing visit. Students completed a pre-post confidence measure, short answer and multiple choice questions, a post-clerkship satisfaction survey, and a standardized medication discrepancy tool. MAIN RESULTS: Overall combined confidence in transitional care skills improved following the TICC from an average score of 2.7 (SD 0.9) to 4.0 (SD 0.8) (p < 0.01) on a 5-point confidence scale. They scored an average of 77% on the written discharge plan portion of the final exam. Students rated the usefulness of TICC at a mean of 3.1 (SD 0.7), above the combined mean of 2.7 for project work in all required clerkships. Students identified medication discrepancies during 43% of post-discharge visits (58 of 136). The most common reasons for discrepancies were patient lack of understanding of instructions and intentional non-adherence to medication plan. CONCLUSION: TICC represents a feasible and effective program to teach evidence-based transitional care.