Modified 5-Item Frailty Index: A Useful Tool for Assessing the Impact of Frailty on Postoperative Morbidity and Mortality Following Surgical Fixation of Thoracolumbar Fractures.

OBJECTIVES: The modified 5-item frailty index (mFI-5) is a comorbidity-based risk stratification tool to predict adverse events following various neurologic surgeries. This study aims to quantify the association between increased mFI-5 and postoperative complications and mortality following surgical fixation of traumatic thoracolumbar fractures. METHODS: The 2011-2021 American College of Surgeons - National Surgical Quality Improvement Program (ACS-NSQIP) dataset was used to identify patients undergoing fusion surgeries for thoracolumbar spine fractures. The mFI-5 score was calculated based on the presence of 5 major comorbidities: congestive heart failure within 30 days before surgery, insulin-dependent or noninsulin-dependent diabetes mellitus, chronic obstructive pulmonary disease, partially dependent or totally dependent functional health status at the time of surgery, and hypertension requiring medication. Multivariate analysis assessed the independent impact of increasing mFI-5 scores on postoperative 30-day morbidity and mortality while controlling for baseline clinical characteristics. RESULTS: A total of 66,904 patients were included in our analysis (54.2% female, mean age 62.27 ± 12.93 years). On univariate analysis, higher mFI-5 score was significantly associated with increased risks of superficial surgical site infection, deep surgical site infection, wound dehiscence, unplanned reoperation, pneumonia, unplanned intubation, postoperative ventilator use, progressive renal insufficiency, acute renal failure, urinary tract infection, stroke, myocardial infarction, cardiac arrest, pulmonary embolism, deep vein thrombosis, bleeding requiring transfusion, sepsis, septic shock, and longer hospital length of stay (LOS). On multivariate logistic regression, increasing mFI-5 score versus a mFI-5 score of zero was associated with higher odds of overall complications (mFI-5 ≥2: odds ratio [OR] 1.38 CI: 1.24-1.54, P < 0.001; mFI-5 = 1: OR 1.18 CI: 1.11-1.24, P < 0.001) and 30-day mortality (mFI-5 ≥2: OR 2.33 CI: 1.60-3.38, P < 0.001). CONCLUSION: This study demonstrates that frailty, when measured using the mFI-5, independently predicts postoperative complications, hospital LOS, and 30-day mortality after surgical repair of thoracolumbar fractures. These findings are important for risk stratification in patients undergoing thoracolumbar fusion surgery and for standardization in reporting outcomes after those procedures.

Effect of ambient temperature on respiratory tract cells exposed to SARS-CoV-2 viral mimicking nanospheres-An experimental study.

The novel coronavirus caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has reached more than 160 countries and has been declared a pandemic. SARS-CoV-2 infects host cells by binding to the angiotensin-converting enzyme 2 (ACE-2) surface receptor via the spike (S) receptor-binding protein (RBD) on the virus envelope. Global data on a similar infectious disease spread by SARS-CoV-1 in 2002 indicated improved stability of the virus at lower temperatures facilitating its high transmission in the community during colder months (December-February). Seasonal viral transmissions are strongly modulated by temperatures, which can impact viral trafficking into host cells; however, an experimental study of temperature-dependent activity of SARS-CoV-2 is still lacking. We mimicked SARS-CoV-2 with polymer beads coated with the SARS-CoV-2 S protein to study the effect of seasonal temperatures on the binding of virus-mimicking nanospheres to lung epithelia. The presence of the S protein RBD on nanosphere surfaces led to binding by Calu-3 airway epithelial cells via the ACE-2 receptor. Calu-3 and control fibroblast cells with S-RBD-coated nanospheres were incubated at 33 and 37 °C to mimic temperature fluctuations in the host respiratory tract, and we found no temperature dependence in contrast to nonspecific binding of bovine serum ablumin-coated nanospheres. Moreover, the ambient temperature changes from 4 to 40 °C had no effect on S-RBD-ACE-2 ligand-receptor binding and minimal effect on the S-RBD protein structure (up to 40 °C), though protein denaturing occurred at 51 °C. Our results suggest that ambient temperatures from 4 to 40 °C have little effect on the SARS-CoV-2-ACE-2 interaction in agreement with the infection data currently reported.

Probing fibrin's molecular response to shear and tensile deformation with coherent Raman microscopy.

Blood clots are essential biomaterials that prevent blood loss and provide a temporary scaffold for tissue repair. In their function, these materials must be capable of resisting mechanical forces from hemodynamic shear and contractile tension without rupture. Fibrin networks, the primary load-bearing element in blood clots, have unique nonlinear mechanical properties resulting from fibrin's hierarchical structure. This structure provides multiscale load bearing from fiber deformation to protein unfolding. Here, we study the fiber and molecular scale response of fibrin under shear and tensile loads in situ using a combination of fluorescence and vibrational (molecular) microscopy. Imaging protein fiber orientation and molecular vibrations, we find that fiber alignment and molecular unfolding in fibrin appear at much larger strains under shear compared to uniaxial tension. Alignment levels reached at 150% shear strain were reached already at 60% tensile strain, and molecular unfolding of fibrin was only detected at shear strains above 300%, whereas fibrin unfolding began already at 20% tensile strain. Moreover, shear deformation caused progressive changes in vibrational modes consistent with increased protofibril and fiber packing that were already present even at very low tensile deformation. Together with a bioinformatic analysis of the primary fibrinogen structure, we propose a scheme for the molecular response of fibrin from low to high deformation, which may relate to the teleological origin of fibrin's resistance to shear and tensile forces.