Faculty Bibliography

BACKGROUND/UNASSIGNED:This study compares outcomes and complications of patients with Bado II Monteggia fracture-dislocations that required radial head fixation or replacement based upon approach to the radial head. METHODS/UNASSIGNED:A retrospective review was performed of 159 consecutive patients with proximal ulna fractures and a radial head dislocation or fracture (Monteggia Variant). Injuries were classified by Bado type. Forty-one patients with Bado II Monteggia injuries treated with either a radial head replacement or fixation with complete follow up were included. Demographics, injury information, surgical details, and follow up information including elbow range of motion (ROM) and complications were collected. A trans-osseous posterior (TOP) approach working through the ulna fracture to address the radial head first was used in 19 patients, while 22 patients had their radial head treated via a separate lateral (Kocher) interval after ulnar fixation. Ulnar plate fixation was performed for all patients. Comparisons were made using independent t-tests. RESULTS/UNASSIGNED:Forty-one Monteggia lesions treated through TOP (19, 46 %) or Kocher (22, 64 %) approaches underwent a radial head replacement (33, 80.5 %) or fracture repair (8, 19.5 %) with a mean final follow-up of 15.3 months. At all post-operative visits, groups displayed similar rates of functional elbow ROM. At latest follow-up rates of patient-reported pain, ultimate elbow ROM, time to radiographic healing were equivalent. No significant differences were observed in ulna non-union, joint malalignment, post-operative nerve injury, post-operative infection, heterotopic ossification, incidence of hardware failure, patient-reported pain, and rate of removal of symptomatic hardware. Sub-analysis of radial head replacement versus fixation revealed equivalent percentage of patients with full ROM at each post-operative time point. CONCLUSION/UNASSIGNED:For Bado II Monteggia fracture-dislocations, the surgical approach to the radial head-TOP versus Kocher-does not influence ultimate patient outcomes or complication rates. Radial head replacement and fixation provide comparable results. LEVEL OF EVIDENCE/UNASSIGNED:III.

Protein-protein interaction (PPI) networks are dynamically remodeled in disease, yet most systems biology approaches focus on changes in protein abundance, overlooking critical interaction-level dysfunction. Here, we present a robust, chemoproteomic method-dysfunctional Protein-Protein Interactome (dfPPI)-that enables high-throughput, systematic, disease-contextual mapping of PPI network dysfunctions in cells and primary human tissue. This method integrates chemical biology probes that selectively capture epichaperome-based interactome assemblies with label-free liquid chromatography-tandem mass spectrometry (LC-MS/MS) and network-based computational analysis, to uncover the rewiring of protein networks not apparent from transcriptomic or proteomic data alone. The dfPPI platform can be applied across disease states, species, and tissues to identify actionable nodes of dysfunction and enable high-resolution, systems-level insights into disease progression. In this protocol, we demonstrate step-by-step procedures for sample preparation, chemical probe treatment, affinity enrichment, label-free LC-MS/MS analysis, and bioinformatics workflows used to generate and interpret dfPPI datasets. This article aims to promote reproducibility and accessibility of this approach, supporting its adoption by the broader systems biology and translational research communities.

Histone modifications play a key role in regulating gene expression and cell fate during development and disease. Current methods for cell-type-specific genome-wide profiling of histone modifications require dissociation and isolation of cells and are not compatible with all tissue types. Here we adapt Targeted DamID (TaDa) to recognize specific histone marks, by fusing chromatin-binding proteins or single-chain antibodies to Dam, an Escherichia coli DNA adenine methylase. When combined with TaDa, this enables cell-type-specific chromatin profiling in intact tissues or organisms. We first profiled H3K4me3, H3K9ac, H3K27me3 and H4K20me1 in vivo in neural stem cells of the developing Drosophila brain. Next, we mapped cell-type-specific H3K4me3, H3K9ac and H4K20me1 distributions in the developing mouse brain. Finally, we injected RNA encoding DamID constructs into 1-cell stage Xenopus embryos to profile H3K4me3 distribution during gastrulation and neurulation. These results illustrate the versatility of TaDa to profile cell-type-specific histone marks throughout the genome in diverse model systems.

Fertility in women decreases with age, but the molecular basis for age-related, unexplained infertility remains elusive. Here, we reveal distinct transcriptome changes in oocytes and surrounding cumulus cells from women in their mid-thirties, as evidenced by notably increased transcription of ribosome genes. Additionally, meiosis genes and actin and cohesin components are downregulated in oocytes with age. Lysosomes and proteostasis are also disrupted in cumulus cells. Moreover, DNA hypomethylation and altered heterochromatin deposition at specific genomic loci are linked to increased transcription of ribosome genes. Rapamycin effectively reduces translation and promotes protein homeostasis in cumulus cells. Remarkably, short-term rapamycin allows patients who fail repeated in vitro fertilization cycles with embryo developmental arrest to achieve high-quality blastocysts that yield successful pregnancy and live birth. These data suggest a causal role for elevated transcription of ribosome genes in aging oocytes and cumulus cells and identify rapamycin as a promising treatment for age-related infertility. This study is registered at Chinese Clinical Trial Registry (ChiCTR2300069828).

BACKGROUND:Accumulated levels of mutant huntingtin protein (mHTT) and its fragments are considered contributors to the pathogenesis of Huntington's disease (HD). Stimulating autophagy may enhance clearance of mHTT and its aggregates which has been considered as a possible therapeutic strategy. However, the role and competence of the autophagy-lysosomal pathway (ALP) during HD progression in the human disease remains largely unknown. METHODS:Here, we used multiplex confocal and ultrastructural immunocytochemical analyses of ALP functional markers in relation to mHTT aggresome pathology in striatum and the less affected cortex or cerebellum of HD brains staged from Grade HD2 to HD4 by Vonsattel neuropathological criteria compared to controls. RESULTS:Immunolabeling revealed the localization of HTT/mHTT in ALP vesicular compartments labeled by autophagy-related adaptor proteins sequestosome 1 (p62/SQSTM1) and ubiquitin, and cathepsin D (CTSD) as well as HTT-positive inclusions. Although comparatively normal at HD2, neurons at later HD stages exhibited progressive enlargement and clustering of CTSD-immunoreactive autolysosomes/lysosomes and, ultrastructurally, autophagic vacuole/lipofuscin granules accumulated progressively, more prominently in striatum than cortex. These changes were accompanied by rises in levels of HTT/mHTT and p62/SQSTM1, particularly their fragments, in striatum but not in the cortex, and by increases of LAMP1 and LAMP2 RNA and LAMP1 protein. In addition, cargo-loaded autophagosomes and cathepsin-positive autolysosomes were readily observed, implying a lack of significant blockage in autophagosome formation and autophagosome-lysosome fusion. CONCLUSIONS:The findings collectively suggest that upregulated lysosomal biogenesis and preserved proteolysis maintain autophagic clearance in early-stage HD, but the observed progressive HTT build-up and AL accumulation at advanced disease stages may signify a failure in autophagy substrate clearance. These findings support the prospect that ALP stimulation applied at early disease stages, when clearance machinery is fully competent, could lead to therapeutic benefits in HD patients.

Expression of the IgE BCR is associated with increased B cell apoptosis, yet in persistent allergy, sustained production of IgE antibodies in the absence of allergen exposure suggests the existence of long-lived IgE plasma cells (PCs). Here we studied the development and localization of IgE PCs in mouse models of allergy. After immunization, IgE PCs underwent maturation in spleen and lymph nodes, acquiring a stable MHCII^loCD93⁺CD98^hiBCR^lo phenotype. Mature IgE PCs had a distinct transcriptional profile adapted to high protein synthesis, glycosylation, and survival and resisted BCR-crosslinking-induced apoptosis. Immunization induced a burst of short-lived IgE PC formation, followed by a reduced differentiation rate over time, compared with IgG1 PCs. Timestamping of PCs revealed long-lived IgE PCs that localize to the spleen, in addition to the bone marrow (BM). Thus, immune challenge can generate both short-lived and long-lived IgE PCs, with long-lived IgE PCs in spleen and BM contributing to allergy persistence.

Astrocytic Ca²⁺ activity regulates activity-dependent synaptic plasticity, but its role in learning-related synaptic changes in the living brain remains unclear. We found that motor training induced synaptic potentiation on apical dendrites of layer 5 pyramidal neurons, as well as astrocytic Ca²⁺ rises in the mouse motor cortex. Reducing astrocytic Ca²⁺ led to synaptic depotentiation during motor training and subsequent impairment in performance improvement. Notably, synaptic depotentiation occurred on a fraction of dendrites with repetitive dendritic Ca²⁺ activity. On those dendrites, dendritic spines that were active before dendritic Ca²⁺ activity underwent CaMKII-dependent size reduction. In addition, the activation of adenosine receptors prevented repetitive dendritic Ca²⁺ activity and synaptic depotentiation caused by the reduction of astrocytic Ca²⁺, suggesting the involvement of ATP released from astrocytes and adenosine signaling in the processes. Together, these findings reveal the function of astrocytic Ca²⁺ in preventing synaptic depotentiation by limiting repetitive dendritic activity during learning.

INTRODUCTION/BACKGROUND:The purpose of this study was to assess the effect of an acute traumatic meniscus tear that required repair in association with a tibial plateau fracture repair on outcomes. METHODS:Over a 17-year period, 843 patients presented with a tibial plateau fracture and were followed prospectively. 721 patients with Schatzker I-VI fractures were treated operatively via a standardized algorithm. 161 tibial plateau fractures (22.3 %) had an associated meniscus tear that underwent acute repair at the time of bony fixation. These patients were compared to operatively repaired tibial plateau fracture patients with no meniscus injury (NMR). Demographics were collected and outcomes including: radiographic healing, knee range of motion (ROM), and complication rates, were recorded. In addition, re-operation rates were compared and any reoperation for meniscus repair failure identified. All patients had a minimum of 1 year follow up. RESULTS:A total of 524 patients with a mean of 21.4 (range: 12-120) months follow up met inclusion criteria. Patients in the meniscus repair (MR) cohort had poorer knee extension (1.01 degrees, range: 0-30 degrees) compared to the NMR cohort (0.07 degrees, range: 0-10 degrees) (p < 0.001), in addition to poorer knee flexion (123 degrees, range: 0-145 degrees, p = 0.024). Additionally, MR patients reported higher pain scores (mean: 3 and range: 0-8, p = 0.005) at latest follow up. Finally, MR patients had higher rates of infection (8.1 % vs. 3.3 %, p = 0.025) and lateral collapse of the joint (p = 0.032). CONCLUSION/CONCLUSIONS:Patients who had a meniscus repair at the time of tibial plateau fracture repair were found to have poorer knee ROM, more patient reported pain at minimum 12 (mean 24) months post-operation. Additionally, these patients developed more post-operative complications than those patients who did not undergo a meniscus repair.