Faculty Bibliography

The ongoing transmission of influenza A viruses (IAV) for the past century continues to be a burden to humans. IAV binds terminal sialic acids (SA) of sugar molecules present within the upper respiratory tract (URT) in order to successfully infect hosts. The two most common SA structures that are important for IAV infection are those with α2,3- and α2,6-linkages. While mice were once considered to be an unsuitable system for studying IAV transmission due to their lack of α2,6-SA in the trachea, we have successfully demonstrated that IAV transmission in infant mice is remarkably efficient. This finding led us to re-evaluate the SA composition of the URT of mice using in situ immunofluorescence and examine its in vivo contribution to transmission for the first time. We demonstrate that mice express both α2,3- and α2,6-SA in the URT and that the difference in expression between infants and adults contributes to the variable transmission efficiencies observed. Furthermore, selectively blocking α2,3-SA or α2,6-SA within the URT of infant mice using lectins was necessary but insufficient at inhibiting transmission, and simultaneous blockade of both receptors was crucial in achieving the desired inhibitory effect. By employing a broadly acting neuraminidase to indiscriminately remove both SA moieties in vivo, we effectively suppressed viral shedding and halted the transmission of different strains of influenza viruses. These results emphasize the utility of the infant mouse model for studying IAV transmission and strongly indicate that broadly targeting host SA is an effective approach that inhibits IAV contagion.IMPORTANCEInfluenza virus transmission studies have historically focused on viral mutations that alter hemagglutinin binding to sialic acid (SA) receptors in vitro. However, SA binding preference does not fully account for the complexities of influenza A virus transmission in humans. Our previous findings reveal that viruses that are known to bind α2,6-SA in vitro have different transmission kinetics in vivo, suggesting that diverse SA interactions may occur during their life cycle. In this study, we examine the role of host SA on viral replication, shedding, and transmission in vivo. We highlight the critical role of SA presence during virus shedding, such that attachment to SA during virion egress is equally important as detachment from SA during virion release. These insights support the potential of broadly acting neuraminidases as therapeutic agents capable of restraining viral transmission in vivo. Our study unveils intricate virus-host interactions during shedding, highlighting the necessity to develop innovative strategies to effectively target transmission.

Clonal expansion refers to the proliferation and selection of advantageous "clones" that are better suited for survival in a Darwinian manner. In recent years, we have greatly enhanced our understanding of cell clonality in the cardiovascular context. However, our knowledge of the underlying mechanisms behind this clonal selection is still severely limited. There is a transpiring pattern of clonal expansion of smooth muscle cells and endothelial cells-and, in some cases, macrophages-in numerous cardiovascular diseases irrespective of their differing microenvironments. These findings indirectly suggest the possible existence of stem-like vascular cells which are primed to respond during disease. Subsequent clones may undergo further phenotypic changes to adopt either protective or detrimental roles. By investigating these clone-forming vascular cells, we may be able to harness this inherent clonal nature for future therapeutic intervention. This review comprehensively discusses what is currently known about clonal expansion across the cardiovascular field. Comparisons of the clonal nature of vascular cells in atherosclerosis (including clonal hematopoiesis of indeterminate potential), pulmonary hypertension, aneurysm, blood vessel injury, ischemia- and tumor-induced angiogenesis, and cerebral cavernous malformations are evaluated. Finally, we discuss the potential clinical implications of these findings and propose that proper understanding and specific targeting of these clonal cells may provide unique therapeutic options for the treatment of these cardiovascular conditions.

OBJECTIVES/OBJECTIVE:The authors report no conflict of interest.To determine if short-term immobilization with a rigid long arm plaster elbow splint after surgery of the arm, elbow, or forearm results in superior outcomes compared with a soft dressing with early motion. DESIGN/METHODS:Prospective Randomized Control Trial. SETTING/METHODS:Academic Medical Center. PATIENT SELECTION CRITERIA/UNASSIGNED:Patients undergoing operative treatment for a mid-diaphysis or distal humerus, elbow, or forearm fracture were consented and randomized according to the study protocol for postoperative application of a rigid elbow splint (10-14 days in a plaster Sugar Tong Splint for forearm fracture or a Long Arm plaster Splint for 10-14 for all others) or soft dressing and allowing immediate free range of elbow and wrist motion (range of motion [ROM]). OUTCOME MEASURES AND COMPARISONS/UNASSIGNED:Self-reported pain (visual analog score or VAS), Healthscale (0-100, 100 denoting excellent health), and physical function (EuroQol 5 Dimension or EQ-5D) surveyed on postoperative days 1-5 and 14 were compared between groups. Patient-reported pain score (0-10, 10 denoting highest satisfaction) at week 6, time to fracture union, ultimate disabilities of the arm, shoulder, and hand score, and elbow ROM were also collected for analysis. Incidence of complications were assessed. RESULTS:Hundred patients (38 men to 62 women with a mean age of 55.7 years) were included. Over the first 5 days and again at postop day 14, the splint cohort reported a higher "Healthscale" from 0 to 100 than the nonsplint group on all study days ( P = 0.041). There was no difference in reported pain between the 2 study groups over the same interval ( P = 0.161 and 0.338 for least and worst pain, respectively), and both groups reported similar rates of treatment satisfaction ( P = 0.30). Physical function ( P = 0.67) and rates of wound problems ( P = 0.27) were similar. Additionally, the mean time to fracture healing was similar for the splint and control groups (4.6 ± 2.8 vs. 4.0 ± 2.2 months, P = 0.34). Ultimate elbow ROM was similar between the study groups ( P = 0.48, P = 0.49, P = 0.61, and P = 0.51 for elbow extension, flexion, pronation, and supination, respectively). CONCLUSIONS:Free range of elbow motion without splinting produced similar results compared with elbow immobilization after surgical intervention for a fracture to the humerus, elbow, and forearm. There was no difference in patient-reported pain outcomes, wound problems, or elbow ROM. Immobilized patients reported slightly higher "healthscale" ratings than nonsplinted patients and, however, reported similar rates of satisfaction. Both treatment strategies are acceptable after upper extremity fracture surgery. LEVEL OF EVIDENCE/METHODS:Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Microsporidia are eukaryotic, obligate intracellular parasites that infect a wide range of hosts, leading to health and economic burdens worldwide. Microsporidia use an unusual invasion organelle called the polar tube (PT), which is ejected from a dormant spore at ultra-fast speeds, to infect host cells. The mechanics of PT ejection are impressive. Anncaliia algerae microsporidia spores (3-4 μm in size) shoot out a 100-nm-wide PT at a speed of 300 μm/s, creating a shear rate of 3000 s^-1. The infectious cargo, which contains two nuclei, is shot through this narrow tube for a distance of ∼60-140 μm (Jaroenlak et al, 2020) and into the host cell. Considering the large hydraulic resistance in an extremely thin tube and the low-Reynolds-number nature of the process, it is not known how microsporidia can achieve this ultrafast event. In this study, we use Serial Block-Face Scanning Electron Microscopy to capture 3-dimensional snapshots of A. algerae spores in different states of the PT ejection process. Grounded in these data, we propose a theoretical framework starting with a systematic exploration of possible topological connectivity amongst organelles, and assess the energy requirements of the resulting models. We perform PT firing experiments in media of varying viscosity, and use the results to rank our proposed hypotheses based on their predicted energy requirement. We also present a possible mechanism for cargo translocation, and quantitatively compare our predictions to experimental observations. Our study provides a comprehensive biophysical analysis of the energy dissipation of microsporidian infection process and demonstrates the extreme limits of cellular hydraulics.

OBJECTIVES/OBJECTIVE:The objective of this study was to ascertain outcome differences after fixation of unstable rotational ankle fractures allowed to weight-bear 2 weeks postoperatively compared with 6 weeks. DESIGN/METHODS:Prospective case-control study. SETTING/METHODS:Academic medical center; Level 1 trauma center. PATIENT SELECTION CRITERIA/UNASSIGNED:Patients with unstable ankle fractures (OTA/AO:44A-C) undergoing open reduction internal fixation (ORIF) were enrolled. Patients requiring trans-syndesmotic fixation were excluded. Two surgeons allowed weight-bearing at 2 weeks postoperatively (early weight-bearing [EWB] cohort). Two other surgeons instructed standard non-weight-bearing until 6 weeks postoperatively (non-weight-bearing cohort). OUTCOME MEASURES AND COMPARISONS/UNASSIGNED:The main outcome measures included the Olerud-Molander questionnaire, the SF-36 questionnaire, and visual analog scale at 6 weeks, 3 months, 6 months, and 12 months postoperatively and complications, return to work, range of ankle motion, and reoperations at 12 months were compared between the 2 cohorts. RESULTS:One hundred seven patients were included. The 2 cohorts did not differ in demographics or preinjury scores ( P > 0.05). Six weeks postoperatively, EWB patients had improved functional outcomes as measured by the Olerud-Molander and SF-36 questionnaires. Early weight-bearing patients also had better visual analog scale scores (standardized mean difference -0.98, 95% confidence interval [CI] -1.27 to -0.70, P < 0.05) and a greater proportion returning to full capacity work at 6 weeks (odds ratio = 3.42, 95% CI, 1.08-13.07, P < 0.05). One year postoperatively, EWB patients had improved pain measured by SF-36 (standardized mean difference 6.25, 95% CI, 5.59-6.92, P < 0.01) and visual analog scale scores (standardized mean difference -0.05, 95% CI, -0.32 to 0.23, P < 0.01). There were no differences in complications or reoperation at 12 months ( P > 0.05). CONCLUSIONS:EWB patients had improved early function, final pain scores, and earlier return to work, without an increased complication rate compared with those kept non-weight-bearing for 6 weeks. LEVEL OF EVIDENCE/METHODS:Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

β-Carotene oxygenase 1 (BCO1) catalyzes the cleavage of β-carotene to form vitamin A. Besides its role in vision, vitamin A regulates the expression of genes involved in lipid metabolism and immune cell differentiation. BCO1 activity is associated with the reduction of plasma cholesterol in humans and mice, while dietary β-carotene reduces hepatic lipid secretion and delays atherosclerosis progression in various experimental models. Here we show that β-carotene also accelerates atherosclerosis resolution in two independent murine models, independently of changes in body weight gain or plasma lipid profile. Experiments in Bco1^-/-