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Where applicable, text in italics describes the underlying philosophy of the requirements in that section. These philosophic statements are not program requirements and are therefore not citable. Note: Review Committees may further specify only where indicated by "The Review Committee may/must further specify."

Trimethylamine N-oxide (TMAO) and urea are two important osmolytes with their main significance to the biophysical field being in how they uniquely interact with proteins. Urea is a strong protein destabilizing agent, whereas TMAO is known to counteract urea's deleterious effects. The exact mechanisms by which TMAO stabilizes and urea destabilizes folded proteins continue to be debated in the literature. Although recent evidence has suggested that urea binds directly to amino acid side chains to make protein folding less thermodynamically favored, it has also been suggested that urea acts indirectly to denature proteins by destabilizing the surrounding hydrogen bonding water networks. Here, we elucidate the molecular level mechanism of TMAO's unique ability to counteract urea's destabilizing nature by comparing Raman spectroscopic frequency shifts to the results of electronic structure calculations of microsolvated molecular clusters. Experimental and computational data suggest that the addition of TMAO into an aqueous solution of urea induces blue shifts in urea's H-N-H symmetric bending modes, which is evidence for direct interactions between the two cosolvents.

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Objectives: To identify a group of ballistic tibia fractures, report the outcomes of these fractures, and compare them with both closed and open tibia fractures sustained by blunt mechanisms. We hypothesized that ballistic tibia fractures and blunt open fractures would have similar outcomes. Design: Retrospective cohort study. Setting: A single Level-1 trauma center. Patients/Participants: Adult patients presenting with ballistic (44), blunt closed (179), or blunt open (179) tibia fractures. Intervention: Intramedullary stabilization of tibia fracture. Main Outcomes: Unplanned reoperation, soft tissue reconstruction, nonunion, compartment syndrome, and fracture-related infection. Results: Compared with the blunt closed group, the ballistic fracture group required more operations (P < 0.01), had a higher occurrence of soft tissue reconstruction (P < 0.01), and higher incidence of compartment syndrome (P = 0.02). Ballistic and blunt closed groups did not significantly differ in rates of unplanned reoperation (P = 0.67), nonunion (11.4% vs. 4.5%, P = 0.08), or deep infection (9.1% vs. 5.6%, P = 0.49). In comparison to the blunt open group, the ballistic group required a similar number of operations (P = 0.12), had similar rates of unplanned reoperation (P = 0.10), soft tissue reconstruction (P = 0.56), nonunion (11.4% vs. 17.9%, P = 0.49), and fracture-related infection (9.1% vs. 10.1%, P = 1.0) but a higher incidence of compartment syndrome (15.9% vs. 5.0%, P = 0.02). Conclusions: Ballistic tibia fractures require more surgeries and have higher rates of soft tissue reconstruction than blunt closed fractures and seem to have outcomes similar to lower severity open fractures. We found a significantly higher rate of compartment syndrome in ballistic tibia fractures than both open and closed blunt fractures. When treating ballistic tibia fractures, surgeons should maintain a high level of suspicion for the development of compartment syndrome and counsel patients that ballistic tibia fractures seem to behave like an intermediate category between closed and open fractures sustained through blunt mechanisms. Level of Evidence: Prognostic Level III. See Instructions for Authors for a complete description of levels of evidence.

Background Intra-articular injections have diagnostic and therapeutic roles in foot and ankle pathologies due to complex anatomy, small size, diverse bones, and joints with proximity in this region. Conventionally, these injections are carried out using anatomical landmark technique and/or fluoroscopic guidance. The small joint space and needle size make the injection challenging. Fluoroscopy is not readily available in the clinical setting; ultrasound-guidance for injections is therefore increasingly being used. We compared the accuracy of intra-articular talonavicular injections using the anatomical landmark technique versus the ultrasound-guided method. Purpose To determine whether ultrasound guidance yields superior results in intra-articular injections of the talonavicular joint compared to injections using palpatory method guided by anatomical landmarks. Material and Methods The feet of 10 cadaveric specimens were held in neutral position by an assistant while a fellowship-trained foot-ankle orthopedic surgeon injected 2 cc of radiopaque dye using anatomical landmarks and palpation method in five specimens and under ultrasound guidance in the remaining five. The needles were left in situ in all specimens and their placement was confirmed fluoroscopically. Results In all five specimens injected under ultrasound guidance, the needle was found to be in the joint, whereas all five injected by palpation only were out of the joint, with one in the naviculo-cuneiform joint, showing ultrasound guidance to significantly increase the accuracy of intra-articular injections in the talonavicular joint than palpatory method alone. Conclusion Ultrasound-guided injections not only confirm correct needle placement, but also delineate any tendon and/or joint pathology simultaneously.

Objectives:The Charlson Comorbidity Index score (CCI) records the presence of comorbidities with various weights for a total score to estimate mortality within 1 year of hospital admission. Our study sought to assess the association of CCI with mortality rates of patients undergoing surgical intervention. Study Design: Retrospective study. Methods: Retrospective study of patients with surgical spinal trauma at a large academic level I trauma tertiary center from 2015 to 2018. Information collected included age, sex, American Society of Anesthesiologists physical status, body mass index, Charlson comorbidities, injury severity score, the presence of spinal cord injury, and mortality. Mortality was measured at 30 days, 90 days, and 1 year. Descriptive and bivariate analyses were completed. The results were significant at P , 0.05. Results: The highest proportion of 1-year mortality was in the patients with cervical (11.3%) and thoracolumbar injuries (7.4%) (P = 0.002). Patients with low CCI had low 1-year mortality (1.7%). Patients with high CCI had high 1-year mortality (13.8%) (P , 0.001). A significant association existed between CCI and mortality at 30 days, 90 days, and 1 year (P , 0.001). Mortality was higher in patients with spinal cord injury (14/108; 13%) than in those without (11/232; 5%) (P = 0.021). No association existed between ISS and mortality (P = 0.26). Discussion: The CCI was associated with a higher proportion of deaths at 30 days, 90 days, and 1 year. This association may help predict this unfortunate complication and guide the surgical team in formulating treatment plans and counseling patients and families regarding mortality associated with these injuries and the risks of surgical intervention.A traumatic spinal injury is a broad term that encompasses a range of injuries such as vertebral body fractures, fracture dislocations, ligamentous disruptions, facet joint injuries, spinal cord injuries, and other

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