Intracellular pH plays a key role in physiology, and its measurement in living specimens remains a crucial task in biology. Fluorescent protein-based pH sensors have gained widespread use, but there is limited spectral diversity for multicolor detection, and it remains a challenge to measure absolute pH values. Here we demonstrate that mCherryTYG is an excellent fluorescence lifetime pH sensor that significantly expands the modalities available for pH quantification in live cells. We first report the 1.09 Å X-ray crystal structure of mCherryTYG, exhibiting a fully matured chromophore. We next determine that it has an extraordinarily large dynamic range with a 2 nanosecond lifetime change from pH 5.5 to pH 9.0. Critically, we find that the sensor maintains a pKa of 6.8 independent of environment, whether as the purified protein in solution or expressed in live cells. Furthermore, the lifetime measurements are ro-bustly independent of total fluorescence intensity and scatter. We demonstrate that mCherryTYG is a highly effective sensor using time resolved fluorescence spectroscopy on live-cell suspensions, which has been previously overlooked as an easily accessible approach for quantifying intracellular pH. As a red fluorescent *

Injuries associated with firearms are a significant health burden. However, there is no comprehensive study of firearm spinal injuries over a large population. It was the purpose of this study to analyze the demographics of spinal firearm injuries across the entire United States for all ages using a national database. Methods A retrospective review of prospectively collected data using the Inter-University Consortium for Political and Social Research Firearm Injury Surveillance Study 1993-2015 (ICPSR 37276) was performed. The demographic variables of patients with spinal injuries due to firearms were analyzed with statistical analyses accounting for the weighted, stratified nature of the data, using SUDAAN 11.0.01™ software (RTI International, Research Triangle Park, North Carolina, 2013). A p-value of < 0.05 was considered statistically significant. Results For the years 1993 through 2015, there were an estimated 2,667,896 emergency department (ED) visits for injuries due to firearms; 10,296 of these injuries (0.4%) involved the spine. The vast majority (98.2%) were due to powder firearm gunshot wounds. Those with a spine injury were more likely to have been injured in an assault (83.7% vs. 60.2%), involved a handgun (83.5% vs. 60.2%), were male (90.8% vs. 86.4%), were admitted to the hospital (86.8% vs. 30.9%), and were seen in urban hospitals (86.7 vs. 64.6%). The average age was 28 years with very few on those < 14 years of age. Illicit drug involvement was over four times as frequent in those with a spine injury (34.7% vs. 8.0%). The cervical spine was involved in 30%, thoracic in 32%, lumbar in 32%, and sacrum in 6%. A fracture occurred in 91.8% and neurologic injury in 33%. Injuries to the thoracic spine had the highest percentage of neurologic involvement (50.4%). There was an annual percentage decrease for patients with and without spine involvement in the 1990s, followed by increases through 2015. The average percentage increase for patients with a spine injury was 10.3% per year from 1997 onwards (p < 10-6), significantly greater than the 1.5% for those without spinal involvement (p = 0.0001) from 1999 onwards. Conclusions This nationwide study of spinal injuries associated with firearms covering all ages can be used as baseline data for future firearm studies. A reduction in the incidence of such injuries can be guided by our findings but may be difficult due to sociopolitical barriers (e.g. socioeconomic status of the injured patients, differences in political opinion regarding gun control in the US, and geospatial patterns of firearm injury).