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Background: Tendinopathies are common in middle-aged women. While estrogen regulates tendon remodeling, the influence of systemic hormone replacement therapy (HRT) on the risk of tendon degeneration remains unclear. Hypothesis/Purpose: The purpose of this study was to investigate the association between systemic HRT use and tendon injuries/repair in perimenopausal women. It was hypothesized that systemic HRT would be associated with an increased incidence of tendon injuries and repair. Study Design: Cohort study; Level of evidence, 4. Methods: Using the TriNetX Research Network, we identified female patients aged ≥45 years diagnosed with major tendon abnormalities, including rotator cuff tears, bicipital tendinitis, lateral or medial epicondylitis, Achilles tendinopathy, patellar tendinitis, or quadriceps strain, from January 2004 to July 2025. HRT exposure was defined as systemic estrogen and/or progestin use within 1 year before a diagnosis. Patients with contraindications to HRT were excluded. After 1:1 propensity score matching, 2 groups of 63,836 patients each were generated. Primary outcomes included diagnosis rates of specific tendon conditions; secondary outcomes were lifetime rates of corresponding tendon repair procedures. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. The independent t test and chi-square test were used for analysis. Results: HRT users had significantly higher rates of several tendon abnormalities compared to matched controls, including rotator cuff tears (39.2% vs 37.9%, respectively; P < .001), bicipital tendinitis (13.3% vs 11.0%, respectively; P < .001), lateral epicondylitis (27.8% vs 22.7%, respectively; P < .001), and medial epicondylitis (6.8% vs 5.3%, respectively; P < .001). Achilles tendinopathy had similar rates between the 2 groups (14.6% vs 14.5%, respectively; P = .387). Surgical repair was more common in the HRT group, including biceps tendon repair/tenodesis (3.9% vs 3.3%, respectively; OR, 1.16 [95% CI, 1.10-1.23]; P < .001), rotator cuff repair (6.6% vs 6.2%, respectively; OR, 1.06 [95% CI, 1.01-1.11]; P = .013), and Achilles tendon repair (0.7% vs 0.6%, respectively; OR, 1.23 [95% CI, 1.06-1.41]; P = .005). Conclusion: Our study showed that systemic HRT use in women aged ≥45 years was associated with an increased risk of tendon injuries and a greater likelihood of surgical repair, although the absolute risk differences were modest. These findings underscore the need for awareness of the possible musculoskeletal effects of hormone therapy and highlight an underexplored area in women's orthopaedic health.

Abstract Background Markerless tumor tracking (MTT) using single‐energy (SE) kilovoltage (kV) imaging has been proposed as a technique for lung tumor motion management. However, bony structures can obscure the tumor and make tracking challenging. Dual‐energy (DE) subtraction imaging can suppress the bone and therefore enhance tumor visibility, potentially improving tracking accuracy. Purpose To develop a machine learning model that predicts the reliability of MTT for SE and DE imaging using phantom and patient data. Methods Images were collected at high and low energy (120/60 kV) using fast‐kV switching on dynamic thorax phantom with 5–15 diameter targets and 20 lung cancer patients, including one patient with two tumor locations. DE images were then generated off‐line using weighted logarithmic subtraction. Separately, a template‐based tracking algorithm was used to track the tumor on both phantom and patient images. For phantom data, the ground truth (GT) was defined by the cos 4 waveform programmed into the motion controller. Since the GT was unknown for patient data, it was estimated using a Kalman filter and further refined using visual inspection. The tracking success rate (TSR) was subsequently calculated. Based on TSR, patients were stratified into three tracking groups: good, moderate, and poor. A logistic regression (LR) model was implemented with tracking features, including match score, peak to side‐peak ratio (PSR), x ‐ and y ‐velocity. To address the distribution differences between phantom and patient data, a domain indicator and interaction features were also incorporated. The model was trained on phantom and 17 patient data using leave‐one‐out cross‐validation, and its performance was evaluated on three held‐out patients, one from each tracking group. Separate LR models were developed for each imaging modality, resulting in SE‐LR and DE‐LR models. For each held‐out patient, the confusion matrix, sensitivity, and specificity were reported. Results For both SE‐LR and DE‐LR models, PSR has the largest coefficient value, indicating that it is the most influential factor when determining the reliability of tracking. At a specificity of 95%, the DE‐LR model achieved significantly higher sensitivity than the SE‐LR model (0.908 vs. 0.731, p < 0.01 for phantom data and 0.657 vs. 0.589, p < 0.01 for patient data). In the three held‐out patients, the DE‐LR model outperformed the SE‐LR model across all metrics. The largest gains were found in the patient with good tracking quality. Conclusions The proposed LR models successfully predicted the reliability of SE‐ and DE‐MTT. Across phantom and patient datasets, the DE‐LR model consistently demonstrated improved performance compared with the SE‐LR model, suggesting that DE imaging may be beneficial for MTT applications.

Abstract Background Sulfhemoglobinemia is a rare but potentially life-threatening dyshemoglobinemia resulting from the irreversible incorporation of sulfur into the heme moiety, producing hemoglobin species incapable of oxygen transport. Its clinical presentation often mimics methemoglobinemia, with cyanosis and oxygen saturation (SpO2) readings discordant from arterial partial pressure of oxygen (PaO2). Phenazopyridine, an over-the-counter urinary analgesic, has been implicated as a rare cause, in 3 previously documented cases. Prompt recognition is essential to avoid inappropriate therapy, particularly methylene blue, which can precipitate hemolysis in patients with glucose-6-phosphate dehydrogenase (G6PD) deficiency. Case Presentation A 71-year-old man with Parkinson’s disease, Crohn’s disease, and chronic anemia presented with unexplained cyanosis and SpO2 readings in the 70-80% range, despite a normal PaO2 of 180 mmHg and absence of respiratory symptoms. He had self-initiated phenazopyridine for dysuria three days prior. CT angiography of the chest and echocardiography with bubble study were unremarkable. Attempts to quantify methemoglobin and carboxyhemoglobin were unsuccessful due to analyzer errors. Laboratory evaluation revealed acute anemia (hemoglobin 5.7 g/dL), indirect hyperbilirubinemia, and low haptoglobin consistent with hemolysis. He was managed supportively with high-flow oxygen, and transfusion of two packed red blood cell units. Although initial G6PD levels were normal, testing during hemolysis can yield false negatives. Given this and the risk of methylene blue-induced oxidative stress, conservative management with ascorbic acid was chosen. The patient’s SpO2 improved gradually, and he was discharged on hospital day three. Send-out tests later confirmed sulfhemoglobinemia (1.1%), elevated cytochrome b5 reductase activity, and normal methemoglobin. Discussion This case underscores the diagnostic and therapeutic challenge of differentiating sulfhemoglobinemia from methemoglobinemia. Both disorders produce functional hypoxia with SpO2-PaO2 dissociation, but sulfhemoglobin cannot revert to hemoglobin and requires erythrocyte turnover for resolution. While methylene blue is the standard therapy for methemoglobinemia, it is ineffective for sulfhemoglobinemia and contraindicated in G6PD deficiency. In our patient, supportive care and transfusion facilitated recovery. Using the Naranjo Adverse Drug Reaction Probability Scale, the causality score was 7, indicating a highly probable relationship between phenazopyridine exposure and sulfhemoglobinemia. A high index of suspicion for G6PD deficiency as well as dyshemoglobinemia with a multidisciplinary collaboration are essential for diagnosis and management of unexplained cyanosis. This abstract is funded by: None

Abstract Rationale The United States has the highest per capita incarceration rate of any developed democracy. As the incarcerated population ages, medically complex and frail patients are increasingly hospitalized in the community, often arriving without decisional capacity and with limited family involvement. This is the first analysis of state laws and policies governing decision-making for incapacitated incarcerated patients. Methods Two team members independently conducted Westlaw and Internet searches for statutes, regulations and department of corrections (DOC) policies from 50 states and the District of Columbia, identifying language about medical decision-making for incapacitated incarcerated patients. These parallel searches were merged into a single database and reviewed by the analytic team, who created a codebook of inductively and deductively derived themes, guided by principles of grounded theory. The codebook was then systematically applied to the database by 2 independent coders; all data were double-coded. Disputes were resolved by consensus with the entire analytic team, in consultation with a legal scholar. Results Thirty-four of 51 jurisdictions have language addressing decision-making for incapacitated incarcerated patients. Data collected include the definition and determination of incapacity, language affirming incarcerated persons’ right to autonomy in medical decision-making, approaches to decision-making for patients with and without surrogate decision-makers, and whether treatment over patient/surrogate objection is authorized. Assertions about the importance of advance care planning (n = 25) are often undercut by procedural hurdles (n = 20), such as complex witnessing requirements for advance directive completion. Many jurisdictions (n = 26) allow family or friends to serve as legally recognized decision-makers. Thirteen jurisdictions exclude an incarcerated person from serving as decision-maker for another incarcerated person. Fourteen jurisdictions have provisions allowing for treatment over the objection of a patient or their surrogate. While approaches to unrepresented patients differ widely (Figure), 5 jurisdictions grant narrow decisional authority to treating physicians and 4 jurisdictions authorize correctional employees to make medical decisions. Conclusion A heterogeneous assortment of laws, policies and regulations govern the care of incapacitated incarcerated patients, with wide variation observed from jurisdiction to jurisdiction. One-third of jurisdictions lack policies or language regarding decision-making processes for incapacitated incarcerated patients. Even more troubling, 14 jurisdictions allow treatment over a patient or surrogate’s objection and 4 jurisdictions delegate authority over decisions for unrepresented patients to correctional employees, such as the prison medical director or the warden. These findings raise serious concerns about autonomy, beneficence and justice. National reform is needed to align correctional policies with established ethical standards for surrogate decision-making. This abstract is funded by: National Institute on Aging

Abstract Introduction The COVID-19 pandemic exposed underrecognized structural deficiencies in pandemic preparedness across the US, particularly impacting marginalized and medically vulnerable populations. State leaders who were developing policies to allocate critical care resources, often called crisis standards of care (CSC), confronted challenges such as whether and how to incorporate age and chronic conditions into triage protocols, how to contend with imperfect illness acuity scores such as the sequential organ failure assessment (SOFA), and whether essential worker status or area deprivation index (ADI) ought to confer an advantage during triage. To our knowledge, this is the first analysis to highlight CSC writers’ approach to ethical challenges, including from states whose policies provoked corrective action from the Office of Civil Rights (OCR). This study explores how state leaders navigated ethical controversies underlying states’ CSC policies, including whether those controversies were satisfactorily resolved. Methods Between February-September 2022 we conducted semi-structured interviews of public health leaders tasked with developing their states’ (CSC) policies. Interviews were transcribed verbatim and a codebook was developed iteratively, using inductively and deductively derived themes based on principles of grounded theory. The codebook was systematically applied to transcripts; disputes were resolved by consensus discussion among analytic team members. Results Leaders from 34 states were interviewed. Participants described how their states’ CSC policy writing committees considered the role of age in triage, some proposing age as a tiebreaker, or considering age only if coupled with measures of frailty or chronic illness, with others proposing age as an “exclusion criterion.” Many leaders acknowledged a controversial approach to disability in early versions of their policies, some describing how they responded to civil rights complaints. Participants described debates over whether pandemic triage decisions should advantage patients from underserved populations or affirmatively consider essential worker status or pregnancy. While most leaders regretted that early iterations of their policies stood to exacerbate health disparities, others described a less conciliatory response to civil rights complaints. In particular, triage exclusion criteria, whereby certain patients would be excluded outright from certain resources, provoked intense debate. Conclusion We describe ethical controversies that stymied CSC policy writing committees during the COVID-19 pandemic. Leaders described spirited debate around how age, disability, and justice ought to factor into triage; few described satisfactory resolution to those debates. Improved community engagement and adherence to civil rights protections in CSC are imperative to protect marginalized populations as we prepare for future calamites, whether global or local. This abstract is funded by: R03 AG73987; K76 AG88403

Key Points In an observational cohort of mostly non-Hispanic White women, pregnancy was not associated with later-life accelerated kidney function decline. Pregnancy occurring during the HALT Progression of Polycystic Kidney Disease (HALT-PKD) trial was not associated with kidney disease progression relative to women who did not become pregnant. Prior evidence indicates that adverse pregnancy outcomes may be involved in autosomal dominant polycystic kidney disease progression; pregnant women should be closely monitored. Background Data are conflicting regarding whether pregnancy influences disease progression in women with autosomal dominant polycystic kidney disease (ADPKD). This study examined whether pregnancy or number of pregnancies was associated with kidney disease progression in women with ADPKD. Methods Women with early- (study A) and late-stage (study B) ADPKD from the HALT Progression of Polycystic Kidney Disease (HALT-PKD) trial were included to examine the association between self-reported number of pregnancies (categorical predictor: no pregnancy versus 1–2 pregnancies and ≥3 pregnancies), annual slope of eGFR, annual percent change in total kidney volume (%ΔTKV), and a composite outcome (kidney failure, 50% decline in eGFR, or death) using multivariable linear regression and Cox proportional hazard models. In addition, women who became pregnant, had full-term pregnancies, and available data during study participation ( n =13) were propensity matched (1:4) to women who were not pregnant during study participation, and a mixed model was applied to determine the association of pregnancy with eGFR slope and %ΔTKV. Results Across all analyses, 455 women with a median age of 45 (interquartile range, 38–50) years and eGFR of 69±25 ml/min per 1.73 m 2 at baseline were included. One hundred ninety-nine women had 1–2 pregnancies, and 165 women had ≥3 pregnancies. There was no association of 1–2 pregnancies or ≥3 pregnancies (versus no pregnancies) with eGFR slope ( β -estimate [95% confidence interval (CI)]; 1–2 pregnancies: 0.22 [−0.44 to 0.89]; ≥3 pregnancies: −0.46 [−1.16 to 0.25]), %ΔTKV ( β -estimate [95% CI]; 1–2 pregnancies: 0.92 [−0.34 to 2.17]; ≥3 pregnancies: 0.69 [−0.67 to 2.04]), or time to composite outcome (hazard ratio [95% CI]; 1–2 pregnancies: 1.04 [0.56 to 1.93]; ≥3 pregnancies: 1.48 [0.78 to 2.77]) in adjusted models. Moreover, there was no difference in annual eGFR slope ( β -estimate: −0.14 [95% CI, −2.72 to 2.44]) and %ΔTKV ( β -estimate: 0.04 [95% CI, −3.74 to 3.82]) in women who became pregnant matched to women who did not became pregnant during their participation in the study. Conclusions Pregnancy was not associated with ADPKD progression among women with early- and late-stage ADPKD enrolled in the HALT-PKD trial.

Obesity is a complex metabolic disease that is the leading risk factor for cardiovascular disease. In obesity, adipose arteries exhibit robust endothelial dysfunction (ED). A major hallmark of ED is loss in flow induced vasodilation (FIV). Kir2.1 is an inwardly rectifying K+ channel that contributes to FIV through the downstream production of nitric oxide, a potent vasodilator. Work from our group demonstrated that in addition to loss in FIV, endothelial cells (ECs) isolated from obese mice exhibited blunted Kir2.1 currents. Plasma long chain fatty acids (LCFAs) are well established to be elevated in obesity and have been separately shown to inhibit Kir2.1 channels. CD36 is the major fatty acid translocase responsible for the uptake of LCFAs and we therefore aimed to determine if CD36 was contributing to this loss in Kir2.1 function. We previously showed that global CD36 ablation restores endothelium-dependent dilations to flow. These findings prompted us to explore the role of EC CD36 in negatively regulating Kir2.1 function. We performed patch clamp electrophysiology experiments on freshly isolated ECs from the Tie2eCreCD36fl/fl model and determined that EC CD36 ablation restores Kir2.1 currents in obesity. To further explore the established relationship between Kir2.1 and FIV, we performed ex vivo pressure myography experiments to evaluate endothelial dependent dilations to flow. EC CD36 ablation restored responses to flow in arteries from obese mice, an effect that could be blunted by inhibiting Kir2.1 suggesting that CD36 ablation in endothelium rescues the Kir2.1 contribution to FIV. To determine if obesity alters the expression of endothelial CD36, arteries from mice and humans undergoing bariatric surgery were isolated and en face preparations were stained to locate the EC layer and assess CD36 expression. Confocal imaging of en face arteries coupled with flow cytometry on isolated endothelial cells revealed that obesity did not alter the expression of CD36 in endothelium of mesenteric arteries relative to controls in WT mice or humans. As expression did not change, we next probed functionality of CD36 in obese vs. control in mice and humans. Arteries were exposed to a fluorescent fatty acid, BODIPY C-16, at various time points followed by en face preparations and confocal microscopy. As expected, obese vessels exhibited elevated amounts of fatty acid uptake (FAU) at all time points relative to control in mice and humans, suggesting an increase in CD36. To further confirm this change in function, we repeated FAU experiments in the Tie2eCreCD36fl/fl model and found that EC CD36 ablation attenuated FAU in obese vessels compared to both their lean and genotype controls. Taken together, this work suggests that an increase in CD36 function drives impairment of Kir2.1. This work establishes a CD36/Kir2.1 axis worthy of further exploration including understanding how CD36 and LCFAs are impairing Kir2.1 upstream. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.