Faculty Bibliography

We sought to determine what effect the size of a displaced coronoid fracture fragment in Monteggia injuries has on clinical outcome. Sixty-seven patients presented to an academic medical center for operative fixation of a Monteggia fracture. Radiographs were assessed for length and height of the displaced coronoid fragment using measuring tools in our center's imaging archive system. Data were analyzed using binary logistic or linear regression, as appropriate, controlling for sex, age, and Charlson Comorbidity Index. Outcome measurements included radiographic healing, range of motion, postoperative complications, and reoperation. The cohort had a mean follow-up of 16.7 months. Mean coronoid fragment area was 362.4±155.9 mm². Elbow range of motion decreased by 3.8° of elbow flexion (P<.001), 3.3° of elbow extension (P<.001), and 3.8° of forearm supination (P=.007) for every 1-cm² increase in coronoid fragment area. Complications (P=.012) and reoperation (P=.036) were associated with increasing coronoid fragment area. Nonunion rate, nerve injury, and pronation range of motion were not correlated to increasing coronoid fracture fragment area (P=.777, P=.123, and P=.351, respectively). As displaced coronoid fragment size increases in Monteggia fracture patterns, elbow range of motion decreases linearly. Coronoid displacement was also associated with increased rates of postoperative complication and need for reoperation. [Orthopedics. 2024;47(1):15-21.].

Peptides that increase pro-reparative responses to injury and disease by modulating the functional organization of hyaluronan (HA) with its cell surface binding proteins (e.g., soluble receptor for hyaluronan-mediated motility [RHAMM] and integral membrane CD44) have potential therapeutic value. The binding of RHAMM to HA is an attractive target, since RHAMM is normally absent or expressed at low levels in homeostatic conditions, but its expression is significantly elevated in the extracellular matrix during tissue stress, response-to-injury, and in cancers and inflammation-based diseases. The HA-binding site in RHAMM contains two closely spaced sequences of clustered basic amino acids, in an alpha-helical conformation. In the present communication, we test whether an alpha-helical conformation is required for effective peptide binding to HA, and competitive disruption of HA-RHAMM interaction. The HA-binding RHAMM-competitive peptide P15-1, identified using the unbiased approach of phage display, was examined using circular dichroism spectroscopy and the conformation-predictive AI-based AlphaFold2 algorithm. Unlike the HA-binding site in RHAMM, peptide P15-1 was found to adopt irregular conformations in solution rather than alpha helices. Instead, our structural analysis suggests that the primary determinant of peptide-HA binding is associated with a specific clustering and spacing pattern of basic amino acids, allowing favorable electrostatic interaction with carboxylate groups on HA.

BACKGROUND/UNASSIGNED:Dying in a preferred place is important for a good death. Currently, no study has evaluated the extent to which the preferences for the place of death (PoD) are met among terminal cancer patients in China. This study examined the congruence between the preferred and actual PoD and its predictors among terminal cancer patients in China. METHODS/UNASSIGNED:Between 2015 and 2023, 845 terminal cancer patients from four tertiary hospitals in Wuhan, China, were enrolled and followed till death. Face-to-face surveys at baseline and telephone-based interviews in the last month of patients' lives were combined to learn patients' preferred PoD. Data on patients' actual PoD were collected from families within 1 month after patients' death. RESULTS/UNASSIGNED: = 0.011), patients were less likely to die in their preferred places. CONCLUSION/UNASSIGNED:The congruence between patients' preferred and actual PoD was fair. Advance care planning (ACP) needs to be popularized in China, and the quality of care in hospice facilities and nursing homes should be improved. The necessary policy support for hospice care should be made to respect cancer patients' end-of-life (EoL) care preferences in China.

Volume electron microscopy encompasses a set of electron microscopy techniques that can be used to examine the ultrastructure of biological tissues and cells in three dimensions. Two block face techniques, focused ion beam scanning electron microscopy (FIB-SEM) and serial block face scanning electron microscopy (SBF-SEM) have often been used to study biological tissue samples. More recently, these techniques have been adapted to in vitro tissue culture samples. Here we describe step-by-step protocols for two sample embedding methods for in vitro tissue culture cells intended to be studied using SBF-SEM. The first focuses on cell pellet embedding and the second on en face embedding. En face embedding can be combined with light microscopy, and this CLEM workflow can be used to identify specific biological events by light microscopy, which can then be imaged using SBF-SEM. We systematically outline the steps necessary to fix, stain, embed and image adherent tissue culture cell monolayers by SBF-SEM. In addition to sample preparation, we discuss optimization of parameters for data collection. We highlight the challenges and key steps of sample preparation, and the consideration of imaging variables.

There has been a paradigm shift towards fixing the posterior malleolus in trimalleolar ankle fractures. This study evaluated whether a surgeon's preference to intraoperatively flip or not flip patients from prone to supine for medial malleolar fixation following repair of fibular and posterior malleoli impacted surgical outcomes. A retrospective patient cohort treated at a large urban academic center and level 1 trauma center was reviewed to identify all operative trimalleolar ankle fractures initially positioned prone. One hundred and forty-seven patients with mean 12-month follow up were included and divided based on positioning for medial malleolar fixation, prone or supine (following closure, flip and re-prep and drape). Data was collected on patient demographics, injury mechanism, perioperative variables, and complication rates. Postoperative reduction films were reviewed by orthopedic traumatologists to grade the accuracy of anatomic fracture reduction. Overall, 74 (50.3%) had the medial malleolus fixed prone, while 73 (49.7%) were flipped and fixed supine. No differences in demographics, injury details, and fracture type existed between the groups. The supine group had a higher rate of initial external fixation (p=0.047), longer operative time in minutes (p<0.001), and a higher use of plate and screw constructs for medial malleolar fixation (p=0.019). There were no differences in clinical and radiographic outcomes and complication rates. This study demonstrated that intraoperative change in positioning for improved medial malleolar visualization in trimalleolar ankle fractures results in longer operative times but similar radiographic and clinical results. The decision of operative position should be based on surgeon comfort.

The gastrointestinal ecosystem has received the most attention when examining the contributions of the human microbiome to health and disease. This concentration of effort is logical due to the overwhelming abundance of microbes in the gut coupled with the relative ease of sampling compared with other organs. However, the intestines are intimately connected to multiple extraintestinal organs, providing an opportunity for homeostatic microbial colonisation and pathogenesis in organs traditionally thought to be sterile or only transiently harbouring microbiota. These habitats are challenging to sample, and their low microbial biomass among large amounts of host tissue can make study challenging. Nevertheless, recent findings have shown that many extraintestinal organs that are intimately linked to the gut harbour stable microbiomes, which are colonised from the gut in selective manners and have highlighted not just the influence of the bacteriome but that of the mycobiome and virome on oncogenesis and health.

Staphylococcus aureus (S. aureus) is a serious global pathogen that causes a diverse range of invasive diseases. S. aureus utilizes a family of pore-forming toxins, known as bi-component leukocidins, to evade the host immune response and promote infection. Among these is LukAB (leukocidin A/leukocidin B), a toxin that assembles into an octameric β-barrel pore in the target cell membrane, resulting in host cell death. The established cellular receptor for LukAB is CD11b of the Mac-1 complex. Here, we show that hydrogen voltage-gated channel 1 is also required for the cytotoxicity of all major LukAB variants. We demonstrate that while each receptor is sufficient to recruit LukAB to the plasma membrane, both receptors are required for maximal lytic activity. Why LukAB requires two receptors, and how each of these receptors contributes to pore-formation remains unknown. To begin to resolve this, we performed an alanine scanning mutagenesis screen to identify mutations that allow LukAB to maintain cytotoxicity without CD11b. We discovered 30 mutations primarily localized in the stem domains of LukA and LukB that enable LukAB to exhibit full cytotoxicity in the absence of CD11b. Using crosslinking, electron microscopy, and hydroxyl radical protein footprinting, we show these mutations increase the solvent accessibility of the stem domain, priming LukAB for oligomerization. Together, our data support a model in which CD11b binding unlatches the membrane penetrating stem domains of LukAB, and this change in flexibility promotes toxin oligomerization.

PURPOSE/OBJECTIVE:To determine the factors associated with discharge location in patients with hip fractures and whether home discharge was associated with a lower readmission and complication rate. METHODS:Hip fracture patients who presented to our academic medical center for operative management of a hip fracture were enrolled into an IRB-approved hip fracture database. Radiographs, demographics, and injury details were recorded at the time of presentation. Patients were grouped based upon discharge disposition: home (with or without home services), acute rehabilitation facility (ARF), or sub-acute rehabilitation facility (SAR). RESULTS:The cohorts differed in marital status, with a greater proportion of patients discharged to home being married (51.7% vs. 43.8% vs. 34.1%) (P < 0.05). Patients discharged to home were less likely to require an assistive device (P < 0.05). Patients discharged to home experienced fewer post-operative complications (P < 0.05) and had lower readmission rates (P < 0.05). Being married was associated with an increased likelihood of discharge to home (OR = 1.679, CI = 1.391-2.028, P < 0.001). Being enrolled in Medicare/Medicaid was associated with decreased odds of discharge to home (OR = 0.563, CI = 0.457-0.693, P < 0.001). Use of an assistive device was associated with decreased odds of discharge to home (OR = 0.398, CI = 0.326-0.468, P < 0.001). Increases in CCI (OR = 0.903, CI = 0.846-0.964, P = 0.002) and number of inpatient complications (OR = 0.708, CI = 0.532-0.943, P = 0.018) were associated with decreased odds of home discharge. CONCLUSION/CONCLUSIONS:Hip fracture patients discharged to home were healthier and more functional at baseline, and also less likely to have had a complicated hospital course. Those discharged to home also had lower rates of readmission and post-operative complications. LEVEL OF EVIDENCE/METHODS:III.

We present an in-depth analysis of selected CASP15 targets, focusing on their biological and functional significance. The authors of the structures identify and discuss key protein features and evaluate how effectively these aspects were captured in the submitted predictions. While the overall ability to predict three-dimensional protein structures continues to impress, reproducing uncommon features not previously observed in experimental structures is still a challenge. Furthermore, instances with conformational flexibility and large multimeric complexes highlight the need for novel scoring strategies to better emphasize biologically relevant structural regions. Looking ahead, closer integration of computational and experimental techniques will play a key role in determining the next challenges to be unraveled in the field of structural molecular biology.

OBJECTIVE:Rejection is common and pernicious following Vascularized Composite Allotransplantation (VCA). Current monitoring and diagnostic modalities include the clinical exam which is subjective and biopsy with dermatohistopathologic Banff grading, which is subjective and invasive. We reviewed literature exploring non- and minimally invasive modalities for diagnosing and monitoring rejection (NIMMs) in VCA. METHODS:PubMed, Cochrane, and Embase databases were queried, 3125 unique articles were reviewed, yielding 26 included studies exploring 17 distinct NIMMs. Broadly, NIMMs involved Imaging, Liquid Biomarkers, Epidermal Sampling, Clinical Grading Scales, and Introduction of Additional Donor Tissue. RESULTS:Serum biomarkers including MMP3 and donor-derived microparticles rose with rejection onset. Epidermal sampling non-invasively enabled measurement of cytokine & gene expression profiles implicated in rejection. Both hold promise for monitoring. Clinical grading scales were useful diagnostically as was reflection confocal microscopy. Introducing additional donor tissue showed promise for preemptively identifying rejection but requires additional allograft tissue burden for the recipient. CONCLUSION/CONCLUSIONS:NIMMs have the potential to dramatically improve monitoring and diagnosis in VCA. Many modalities show promise however, additional research is needed and a multimodal algorithmic approach should be explored.