Sex-dependent effects in the aged melanoma tumor microenvironment influence invasion and resistance to targeted therapy.

There is documented sex disparity in cutaneous melanoma incidence and mortality, increasing disproportionately with age and in the male sex. However, the underlying mechanisms remain unclear. While biological sex differences and inherent immune response variability have been assessed in tumor cells, the role of the tumor-surrounding microenvironment, contextually in aging, has been overlooked. Here, we show that skin fibroblasts undergo age-mediated, sex-dependent changes in their proliferation, senescence, ROS levels, and stress response. We find that aged male fibroblasts selectively drive an invasive, therapy-resistant phenotype in melanoma cells and promote metastasis in aged male mice by increasing AXL expression. Intrinsic aging in male fibroblasts mediated by EZH2 decline increases BMP2 secretion, which in turn drives the slower-cycling, highly invasive, and therapy-resistant melanoma cell phenotype, characteristic of the aged male TME. Inhibition of BMP2 activity blocks the emergence of invasive phenotypes and sensitizes melanoma cells to BRAF/MEK inhibition.

PEBP1 Wardens Ferroptosis by Enabling Lipoxygenase Generation of Lipid Death Signals.

Ferroptosis is a form of programmed cell death that is pathogenic to several acute and chronic diseases and executed via oxygenation of polyunsaturated phosphatidylethanolamines (PE) by 15-lipoxygenases (15-LO) that normally use free polyunsaturated fatty acids as substrates. Mechanisms of the altered 15-LO substrate specificity are enigmatic. We sought a common ferroptosis regulator for 15LO. We discovered that PEBP1, a scaffold protein inhibitor of protein kinase cascades, complexes with two 15LO isoforms, 15LO1 and 15LO2, and changes their substrate competence to generate hydroperoxy-PE. Inadequate reduction of hydroperoxy-PE due to insufficiency or dysfunction of a selenoperoxidase, GPX4, leads to ferroptosis. We demonstrated the importance of PEBP1-dependent regulatory mechanisms of ferroptotic death in airway epithelial cells in asthma, kidney epithelial cells in renal failure, and cortical and hippocampal neurons in brain trauma. As master regulators of ferroptotic cell death with profound implications for human disease, PEBP1/15LO complexes represent a new target for drug discovery.

Natural neural projection dynamics underlying social behavior.

Social interaction is a complex behavior essential for many species and is impaired in major neuropsychiatric disorders. Pharmacological studies have implicated certain neurotransmitter systems in social behavior, but circuit-level understanding of endogenous neural activity during social interaction is lacking. We therefore developed and applied a new methodology, termed fiber photometry, to optically record natural neural activity in genetically and connectivity-defined projections to elucidate the real-time role of specified pathways in mammalian behavior. Fiber photometry revealed that activity dynamics of a ventral tegmental area (VTA)-to-nucleus accumbens (NAc) projection could encode and predict key features of social, but not novel object, interaction. Consistent with this observation, optogenetic control of cells specifically contributing to this projection was sufficient to modulate social behavior, which was mediated by type 1 dopamine receptor signaling downstream in the NAc. Direct observation of deep projection-specific activity in this way captures a fundamental and previously inaccessible dimension of mammalian circuit dynamics.

Homogeneous Oligomers of Pro-apoptotic BAX Reveal Structural Determinants of Mitochondrial Membrane Permeabilization.

BAX is a pro-apoptotic protein that transforms from a cytosolic monomer into a toxic oligomer that permeabilizes the mitochondrial outer membrane. How BAX monomers assemble into a higher-order conformation, and the structural determinants essential to membrane permeabilization, remain a mechanistic mystery. A key hurdle has been the inability to generate a homogeneous BAX oligomer (BAXO) for analysis. Here, we report the production and characterization of a full-length BAXO that recapitulates physiologic BAX activation. Multidisciplinary studies revealed striking conformational consequences of oligomerization and insight into the macromolecular structure of oligomeric BAX. Importantly, BAXO enabled the assignment of specific roles to particular residues and α helices that mediate individual steps of the BAX activation pathway, including unexpected functionalities of BAX α6 and α9 in driving membrane disruption. Our results provide the first glimpse of a full-length and functional BAXO, revealing structural requirements for the elusive execution phase of mitochondrial apoptosis.

α-Synuclein strain propagation is independent of cellular prion protein expression in a transgenic synucleinopathy mouse model.

The cellular prion protein, PrPC, has been postulated to function as a receptor for α-synuclein, potentially facilitating cell-to-cell spreading and/or toxicity of α-synuclein aggregates in neurodegenerative disorders such as Parkinson's disease. Previously, we generated the "Salt (S)" and "No Salt (NS)" strains of α-synuclein aggregates that cause distinct pathological phenotypes in M83 transgenic mice overexpressing A53T-mutant human α-synuclein. To test the hypothesis that PrPC facilitates the propagation of α-synuclein aggregates, we produced M83 mice that either express or do not express PrPC. Following intracerebral inoculation with the S or NS strain, the absence of PrPC in M83 mice did not prevent disease development and had minimal influence on α-synuclein strain-specified attributes such as the extent of cerebral α-synuclein deposition, selective targeting of specific brain regions and cell types, the morphology of induced α-synuclein deposits, and the structural fingerprints of protease-resistant α-synuclein aggregates. Likewise, there were no appreciable differences in disease manifestation between PrPC-expressing and PrPC-lacking M83 mice following intraperitoneal inoculation of the S strain. Interestingly, intraperitoneal inoculation with the NS strain resulted in two distinct disease phenotypes, indicative of α-synuclein strain evolution, but this was also independent of PrPC expression. Overall, these results suggest that PrPC plays at most a minor role in the propagation, neuroinvasion, and evolution of α-synuclein strains in mice that express A53T-mutant human α-synuclein. Thus, other putative receptors or cell-to-cell propagation mechanisms may have a larger effect on the spread of α-synuclein aggregates during disease.

The molecular determinants of a universal prion acceptor.

In prion diseases, the species barrier limits the transmission of prions from one species to another. However, cross-species prion transmission is remarkably efficient in bank voles, and this phenomenon is mediated by the bank vole prion protein (BVPrP). The molecular determinants of BVPrP's ability to function as a universal prion acceptor remain incompletely defined. Building on our finding that cultured cells expressing BVPrP can replicate both mouse and hamster prion strains, we systematically identified key residues in BVPrP that permit cross-species prion replication. We found that residues N155 and N170 of BVPrP, which are absent in mouse PrP but present in hamster PrP, are critical for cross-species prion replication. Additionally, BVPrP residues V112, I139, and M205, which are absent in hamster PrP but present in mouse PrP, are also required to enable replication of both mouse and hamster prions. Unexpectedly, we found that residues E227 and S230 near the C-terminus of BVPrP severely restrict prion accumulation following cross-species prion challenge, suggesting that they may have evolved to counteract the inherent propensity of BVPrP to misfold. PrP variants with an enhanced ability to replicate both mouse and hamster prions displayed accelerated spontaneous aggregation kinetics in vitro. These findings suggest that BVPrP's unusual properties are governed by a key set of amino acids and that the enhanced misfolding propensity of BVPrP may enable cross-species prion replication.

Anti-prion drugs do not improve survival in novel knock-in models of inherited prion disease.

Prion diseases uniquely manifest in three distinct forms: inherited, sporadic, and infectious. Wild-type prions are responsible for the sporadic and infectious versions, while mutant prions cause inherited variants like fatal familial insomnia (FFI) and familial Creutzfeldt-Jakob disease (fCJD). Although some drugs can prolong prion incubation times up to four-fold in rodent models of infectious prion diseases, no effective treatments for FFI and fCJD have been found. In this study, we evaluated the efficacy of various anti-prion drugs on newly-developed knock-in mouse models for FFI and fCJD. These models express bank vole prion protein (PrP) with the pathogenic D178N and E200K mutations. We applied various drug regimens known to be highly effective against wild-type prions in vivo as well as a brain-penetrant compound that inhibits mutant PrPSc propagation in vitro. None of the regimens tested (Anle138b, IND24, Anle138b + IND24, cellulose ether, and PSCMA) significantly extended disease-free survival or prevented mutant PrPSc accumulation in either knock-in mouse model, despite their ability to induce strain adaptation of mutant prions. Our results show that anti-prion drugs originally developed to treat infectious prion diseases do not necessarily work for inherited prion diseases, and that the recombinant sPMCA is not a reliable platform for identifying compounds that target mutant prions. This work underscores the need to develop therapies and validate screening assays specifically for mutant prions, as well as anti-prion strategies that are not strain-dependent.

Helminth infection driven gastrointestinal hypermotility is independent of eosinophils and mediated by alterations in smooth muscle instead of enteric neurons.

Intestinal helminth infection triggers a type 2 immune response that promotes a 'weep-and sweep' response characterised by increased mucus secretion and intestinal hypermotility, which function to dislodge the worm from its intestinal habitat. Recent studies have discovered that several other pathogens cause intestinal dysmotility through major alterations to the immune and enteric nervous systems (ENS), and their interactions, within the gastrointestinal tract. However, the involvement of these systems has not been investigated for helminth infections. Eosinophils represent a key cell type recruited by the type 2 immune response and alter intestinal motility under steady-state conditions. Our study aimed to investigate whether altered intestinal motility driven by the murine hookworm, Nippostrongylus brasiliensis, infection involves eosinophils and how the ENS and smooth muscles of the gut are impacted. Eosinophil deficiency did not influence helminth-induced intestinal hypermotility and hypermotility did not involve gross structural or functional changes to the ENS. Hypermotility was instead associated with a dramatic increase in smooth muscle thickness and contractility, an observation that extended to another rodent nematode, Heligmosomoides polygyrus. In summary our data indicate that, in contrast to other pathogens, helminth-induced intestinal hypermotility is driven by largely by myogenic, rather than neurogenic, alterations with such changes occurring independently of eosinophils. (<300 words).

Ethical frameworks should be applied to computational modelling of infectious disease interventions.

This perspective is part of an international effort to improve epidemiological models with the goal of reducing the unintended consequences of infectious disease interventions. The scenarios in which models are applied often involve difficult trade-offs that are well recognised in public health ethics. Unless these trade-offs are explicitly accounted for, models risk overlooking contested ethical choices and values, leading to an increased risk of unintended consequences. We argue that such risks could be reduced if modellers were more aware of ethical frameworks and had the capacity to explicitly account for the relevant values in their models. We propose that public health ethics can provide a conceptual foundation for developing this capacity. After reviewing relevant concepts in public health and clinical ethics, we discuss examples from the COVID-19 pandemic to illustrate the current separation between public health ethics and infectious disease modelling. We conclude by describing practical steps to build the capacity for ethically aware modelling. Developing this capacity constitutes a critical step towards ethical practice in computational modelling of public health interventions, which will require collaboration with experts on public health ethics, decision support, behavioural interventions, and social determinants of health, as well as direct consultation with communities and policy makers.

The importance of prion research.

Over the past four decades, prion diseases have received considerable research attention owing to their potential to be transmitted within and across species as well as their consequences for human and animal health. The unprecedented nature of prions has led to the discovery of a paradigm of templated protein misfolding that underlies a diverse range of both disease-related and normal biological processes. Indeed, the "prion-like" misfolding and propagation of protein aggregates is now recognized as a common underlying disease mechanism in human neurodegenerative disorders such as Alzheimer's and Parkinson's disease, and the prion principle has led to the development of novel diagnostic and therapeutic strategies for these illnesses. Despite these advances, research into the fundamental biology of prion diseases has declined, likely due to their rarity and the absence of an acute human health crisis. Given the past translational influence, continued research on the etiology, pathogenesis, and transmission of prion disease should remain a priority. In this review, we highlight several important "unsolved mysteries" in the prion disease research field and how solving them may be crucial for the development of effective therapeutics, preventing future outbreaks of prion disease, and understanding the pathobiology of more common human neurodegenerative disorders.

Real-world treatment outcomes of systemic treatments for moderate-to-severe atopic dermatitis in children aged less than 12 years: 2-year results from PEDISTAD.

BACKGROUND: The arrival of biologics and small-molecule therapies (e.g. Janus kinase inhibitors) changed atopic dermatitis (AD) treatment, but older systemic treatments continue to be prescribed. OBJECTIVE: To provide real-world effectiveness, safety, and adherence data for dupilumab, cyclosporine, and methotrexate. METHODS: PEDISTAD (NCT03687359) is a real-world, prospective, observational, 10-year study of children (<12 years) with inadequately controlled moderate-to-severe AD. We report 2-year interim results. RESULTS: Median treatment durations were 8.1, 13.0, and 10.7 months for dupilumab (n = 144), methotrexate (n = 114), and cyclosporine (n = 121), respectively. Dupilumab had numerically greater within-group improvements than methotrexate and cyclosporine in Eczema Area and Severity Index (-12.4* vs -5.7* and -3.3); body surface area affected (-19.9%* vs -11.8%* and -8.8%*); itching (nighttime: -2.1* vs -0.4 and +0.1; daytime: -1.5* vs +0.1 and +0.2; ≥6 years); itching/scratching (-3.6* vs -1.4* and -0.2; <6 years); and Patient-Oriented Eczema Measure (-7.0* vs -4.7* and -1.5) (*P < .05 within-group improvements from baseline). Dupilumab had less discontinuations (8.3% vs 28.9% and 43.0%) and adverse event(s) (18.1% vs 29.8% and 31.4%). LIMITATIONS: No randomization, placebo, or specified dosages. CONCLUSION: Dupilumab was associated with numerically greater outcomes and higher adherence than cyclosporine or methotrexate.

Do community changes persist after irruptive population dynamics? A case study from an invasive species boom and bust.

Irruptive or boom-and-bust population dynamics, also known as 'outbreaks', are an important phenomenon that has been noted in biological invasions at least since Charles Elton's classic book was published in 1958. Community-level consequences of irruptive dynamics are poorly documented and invasive species provide excellent systems for their study. African Jewelfish (Rubricatochromis letourneuxi, "jewelfish") are omnivores that demonstrate opportunistic carnivory, first reported in Florida in the 1960s and in Everglades National Park (ENP) in 2000. Twelve years after invasion in ENP, jewelfish underwent a 25-fold increase in density in one year. By 2016, jewelfish represented 25-50% of fish biomass. Using a 43-year fish community dataset at two sites (1978-2021), and a 25-year dataset of fish and invertebrate communities from the same drainage (1996-2021), with additional spatial coverage, we quantified differences in fish and invertebrate communities during different phases of invasion. During jewelfish boom, abundant, native cyprinodontiform fishes decreased in density and drove changes in community structure as measured by similarity of relativized abundance. Density of two species declined by > 70%, while four declined by 50-62%. Following the jewelfish bust, some species recovered to pre-boom densities while others did not. Diversity of recovery times produced altered community structure that lagged for at least four years after the jewelfish population declined. Community structure is an index of ecological functions such as resilience, productivity, and species interaction webs; therefore, these results demonstrate that irruptive population dynamics can alter ecological functions of ecosystems mediated by community structure for years following that population's decline.

Arctic soil patterns analogous to fluid instabilities.

Slow-moving arctic soils commonly organize into striking large-scale spatial patterns called solifluction terraces and lobes. Although these features impact hillslope stability, carbon storage and release, and landscape response to climate change, no mechanistic explanation exists for their formation. Everyday fluids-such as paint dripping down walls-produce markedly similar fingering patterns resulting from competition between viscous and cohesive forces. Here we use a scaling analysis to show that soil cohesion and hydrostatic effects can lead to similar large-scale patterns in arctic soils. A large dataset of high-resolution solifluction lobe spacing and morphology across Norway supports theoretical predictions and indicates a newly observed climatic control on solifluction dynamics and patterns. Our findings provide a quantitative explanation of a common pattern on Earth and other planets, illuminating the importance of cohesive forces in landscape dynamics. These patterns operate at length and time scales previously unrecognized, with implications toward understanding fluid-solid dynamics in particulate systems with complex rheology.

Pediatric dermatofibromas: Truncal predominance in younger children.

Pediatric dermatofibromas are considered rare in young children and have not been well characterized, often misdiagnosed clinically. We performed a retrospective case series of children younger than 18 years with histopathologically diagnosed dermatofibromas at our institutions and evaluated age at onset and diagnosis, sex, lesion location, and size, associated symptoms, change over time, and pre-biopsy diagnosis. Overall, dermatofibromas were most common on the back and chest (20/53; 38%), followed by the legs (15/53; 28%) and arms (12/53; 23%) with the most common pre-biopsy diagnosis of "cyst" (23/53; 43%), followed by dermatofibroma (16/53; 30%), and pilomatricoma (12/53; 23%). Our study reinforces previous findings of truncal predominance of pediatric dermatofibromas, different from adults.

Large age shifts in HIV-1 incidence patterns in KwaZulu-Natal, South Africa.

Recent declines in adult HIV-1 incidence have followed the large-scale expansion of antiretroviral therapy and primary HIV prevention across high-burden communities of sub-Saharan Africa. Mathematical modeling suggests that HIV risk will decline disproportionately in younger adult age-groups as interventions scale, concentrating new HIV infections in those >age 25 over time. Yet, no empirical data exist to support these projections. We conducted a population-based cohort study over a 16-y period (2004 to 2019), spanning the early scale-up of antiretroviral therapy and voluntary medical male circumcision, to estimate changes in the age distribution of HIV incidence in a hyperepidemic region of KwaZulu-Natal, South Africa, where adult HIV incidence has recently declined. Median age of HIV seroconversion increased by 5.5 y in men and 3.0 y in women, and the age of peak HIV incidence increased by 5.0 y in men and 2.0 y in women. Incidence declined disproportionately among young men (64% in men 15 to 19, 68% in men 20 to 24, and 46% in men 25 to 29) and young women (44% in women 15 to 19, 24% in women 20 to 24) comparing periods pre- versus post-universal test and treat. Incidence was stable (<20% change) in women aged 30 to 39 and men aged 30 to 34. Age shifts in incidence occurred after 2012 and were observed earlier in men than in women. These results provide direct epidemiological evidence of the changing demographics of HIV risk in sub-Saharan Africa in the era of large-scale treatment and prevention. More attention is needed to address lagging incidence decline among older individuals.

Phase separation in the outer membrane of Escherichia coli.

Gram-negative bacteria are surrounded by a protective outer membrane (OM) with phospholipids in its inner leaflet and lipopolysaccharides (LPS) in its outer leaflet. The OM is also populated with many ß-barrel outer-membrane proteins (OMPs), some of which have been shown to cluster into supramolecular assemblies. However, it remains unknown how abundant OMPs are organized across the entire bacterial surface and how this relates to the lipids in the membrane. Here, we reveal how the OM is organized from molecular to cellular length scales, using atomic force microscopy to visualize the OM of live bacteria, including engineered Escherichia coli strains and complemented by specific labeling of abundant OMPs. We find that a predominant OMP in the E. coli OM, the porin OmpF, forms a near-static network across the surface, which is interspersed with barren patches of LPS that grow and merge with other patches during cell elongation. Embedded within the porin network is OmpA, which forms noncovalent interactions to the underlying cell wall. When the OM is destabilized by mislocalization of phospholipids to the outer leaflet, a new phase appears, correlating with bacterial sensitivity to harsh environments. We conclude that the OM is a mosaic of phase-separated LPS-rich and OMP-rich regions, the maintenance of which is essential to the integrity of the membrane and hence to the lifestyle of a gram-negative bacterium.

Staged Hip Arthroscopy with Labral Repair, Femoroplasty, and Capsular Plication Followed by Periacetabular Osteotomy for Hip Dysplasia Results in Improved Outcomes and 100% Survivorship at Minimum 2-Year Follow-Up.

PURPOSE: To assess patient-reported outcomes (PROs), clinically significant outcomes (CSOs), and survivorship following staged hip arthroscopy with labral repair, femoroplasty, and capsular plication followed by periacetabular osteotomy (PAO) for the management of femoroacetabular impingement syndrome (FAIS) and hip dysplasia (lateral center edge angle ≤25°). METHODS: A prospectively maintained database was queried to retrospectively identify patients who underwent staged primary hip arthroscopy and PAO between 1/2018-10/2021 and had a minimum 2-year follow-up. PROs collected included, Hip Outcome Score Activities of Daily Living/Sports Subscale (HOS-ADL/SS), international Hip Outcome Tool-12 item questionnaire (iHOT-12), and Visual Analog Scale for Pain (VAS Pain). CSO achievement for minimal clinical important difference (MCID) and patient acceptable symptom state (PASS) were determined through cohort specific thresholds. Rates of reoperation, including, revision hip arthroscopy and conversion to total hip arthroplasty (THA) were evaluated to determine short-term survivorship. RESULTS: Thirty-nine hips met criteria for inclusion, of which 35 hips had minimum 2-year follow up (89.7% compliance). Mean age was 25±9.1 years and 91.7% of patients were female. Respective pre- and postoperative radiographic outcomes were: Alpha angle 59.8±5.9 to 39.7±2.6°, Tönnis angle 14.6±5.6° to -1.0±2.9°, lateral center-edge angle 16.6±5.5° to 36.6±4.6°, and anterior center-edge angle 15.6±9.1° to 36.1±3.8°, with statistically significant differences pre- to postoperatively for all (P<0.001). Patients demonstrated significant improvement in all PROs pre- to postoperatively (P ≤0.004). MCID and PASS achievement rates for any PRO were 93.9% and 78.8%, respectively. There were no revision hip surgeries or conversion to THA at a mean 2.7±1.0-year follow-up. Four patients (11.1%) underwent hardware removal. One patient (2.8%) experienced a postoperative infection treated with incision and drainage. CONCLUSIONS: Staged hip arthroscopy and PAO for the management of hip dysplasia demonstrated improvement in PROs, high CSO achievement rates, and 100% survivorship at minimum 2-year follow-up.

A Comparison of Tenosynovial and Transverse Carpal Ligament Biopsy for Amyloid Detection in Open Carpal Tunnel Release.

PURPOSE: Our purpose was to compare differences in the incidence of amyloid deposition in tenosynovium (TS) versus transverse carpal ligament (TCL) biopsies obtained during open carpal tunnel release. We hypothesized that the incidence of amyloid would be similar between TCL and TS when obtaining both specimens from the same patient. METHODS: All primary, elective open carpal tunnel release cases that underwent biopsy for amyloid between January 2022 and September 2023 were reviewed. Tenosynovial and TCL specimens were independently evaluated by a pathologist to assess for amyloid. Demographic data were collected, and incidence of amyloid deposition was compared between the two samples. Agreement statistics, sensitivity, and specificity were calculated for TCL, using TS as the reference standard. RESULTS: A total of 196 cases met either Tier 1 (n=180) or Tier 2 (n=16) biopsy criteria. Forty-eight cases were excluded for missed biopsies or laboratory processing errors, leaving 148 cases available for analysis. Amyloid deposition was present in 31 out of 148 (21%) TS specimens and 33 out of 148 (22%) TCL specimens. Overall, the results of the TS biopsy agreed with TCL biopsy in 138 out of 148 cases (93%). In the 10 cases for which the results of the TCL and TS biopsy differed, six cases had (+) TCL and (-) TS, and four cases had amyloid deposition in TS without evidence of deposition in the TCL. Sensitivity and specificity values for the TCL specimen were 87% and 95%, respectively. Positive and negative predictive values were 82% and 97%, respectively. CONCLUSIONS: For cases of open carpal tunnel release undergoing biopsy, amyloid deposition was noted in 21% of TS specimens and 22% of TCL specimens. Results of TS and TCL biopsies obtained from the same patient agreed in 93% of cases. Single-source biopsy for amyloid represents a reasonable diagnostic approach. Future cost analyses should be performed to determine whether the addition of two biopsy sources to improve diagnostic accuracy is justified. TYPE OF STUDY/LEVEL OF EVIDENCE: Prognostic II.

Sensitivity, Specificity, and Reliability of the CTS-6 for Carpal Tunnel Syndrome Administered by Medical Assistants.

PURPOSE: The CTS-6 can be used clinically to diagnose carpal tunnel syndrome (CTS) and has demonstrated high levels of interrater reliability when administered by nonexpert clinicians. Our purpose was to assess sensitivity (Sn), specificity (Sp), and interrater reliability of the CTS-6 when administered by medical assistants (MAs). METHODS: A series of patients presenting to an academic, upper-extremity surgery clinic were screened using CTS-6 between May and June of 2023. The CTS-6 was first administered by one of seven MAs and then by one of four fellowship-trained upper-extremity surgeons. In addition to recording baseline demographics, the results of each of the six history and examination components of the CTS-6 were recorded, as was the cumulative CTS-6 score (0-26). Surgeons were blinded to the scores obtained by the MAs. Interrater reliability (Cohen's kappa) was determined between the groups with respect to the diagnosis of CTS and the individual CTS-6 items. Sensitivity/specificity was calculated for the MA-administered CTS-6, using the score obtained by the surgeon as the reference standard. A CTS-6 score >12 was considered diagnostic of CTS. RESULTS: Two hundred eighteen patients were included, and 26% had a diagnosis of CTS. The MA group demonstrated a Sn/Sp of 84%/91% for the diagnosis of CTS. Interrater reliability was substantial (Cohen's kappa: 0.72, 95% confidence interval: 0.62-0.83) for MAs compared with hand surgeons for the diagnosis of CTS. For individual CTS-6 components, agreement was lowest for the assessment of two-point discrimination (fair) and highest for the assessment of subjective numbness (near perfect). CONCLUSIONS: The CTS-6 demonstrates substantial reliability and high Sn/Sp when administrated by MAs in an upper-extremity clinic. These data may be used to inform the development of CTS screening programs and future investigations in the primary care setting. TYPE OF STUDY/LEVEL OF EVIDENCE: Diagnostic II.

A Comparison of Amyloid Deposition in Endoscopic and Open Carpal Tunnel Release.

PURPOSE: Previous investigations assessing the incidence of amyloidosis detected with biopsy during carpal tunnel release (CTR) have focused on open CTR (OCTR). Prior authors have suggested that biopsy may be more technically challenging during endoscopic carpal tunnel release (ECTR). Our purpose was to compare differences in the incidence of amyloid deposition detected during ECTR versus OCTR. METHODS: We reviewed all primary ECTR and OCTR during which a biopsy for amyloid was obtained between February 2022 and June 2023. All procedures were performed by five upper-extremity surgeons from a single institution. Congo red staining was used to determine the presence of amyloid deposition in either the transverse carpal ligament (TCL) or tenosynovium. All positive cases underwent subtype analysis and protein identification through liquid chromatography-tandem mass spectrometry. Baseline demographics were recorded for each case, and the incidence of positive biopsy was compared between ECTR and OCTR cases. RESULTS: A total of 282 cases were included for analysis (143 ECTR and 139 OCTR). The mean age was 67 years, and 45% of cases were women. Baseline demographics were similar except for a significantly higher incidence of diabetes in OCTR cases (13% vs 33%). Overall, 13% of CTR cases had a positive biopsy. There was a statistically significant difference in the incidence of amyloid deposition detected during biopsy in ECTR cases (3.5%) compared with OCTR cases (23%). CONCLUSIONS: Biopsy performed during ECTR may result in a lower incidence of amyloid detection. Future basic science investigation may be necessary to determine histologic differences between tenosynovium proximal and distal to the leading edge of the TCL. When surgeons plan a biopsy during surgical release of the carpal tunnel, an open approach may be advantageous. TYPE OF STUDY/LEVEL OF EVIDENCE: Prognostic II.