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Importance Tau positron emission tomography (PET) allows in vivo detection of neurofibrillary tangles, a core neuropathologic feature of Alzheimer disease (AD). Objective To provide estimates of the frequency of tau PET positivity and its associated risk of clinical outcomes. Design, Setting, and Participants Longitudinal study using data pooled from 21 cohorts, comprising a convenience sample of 6514 participants from 13 countries, collected between January 2013 and June 2024. Cognitively unimpaired individuals and patients with a clinical diagnosis of mild cognitive impairment (MCI), AD dementia, or other neurodegenerative disorders were included. Exposures Tau PET with flortaucipir F 18, amyloid-β (Aβ) PET, and clinical examinations. Tau PET scans were visually rated as positive according to a US Food and Drug Administration– and European Medicines Agency–approved method, designed to indicate the presence of advanced neurofibrillary tangle pathology (Braak stages V-VI). Main Outcomes and Measures Frequency of tau PET positivity and absolute risk of clinical progression (eg, progression to MCI or dementia). Results Among the 6514 participants (mean age, 69.5 years; 50.5% female), median follow-up time ranged from 1.5 to 4.0 years. Of 3487 cognitively unimpaired participants, 349 (9.8%) were tau PET positive; the estimated frequency of tau PET positivity was less than 1% in those aged younger than 50 years, and increased from 3% (95% CI, 2%-4%) at 60 years to 19% (95% CI, 16%-24%) at 90 years. Tau PET positivity frequency estimates increased across MCI and AD dementia clinical diagnoses (43% [95% CI, 41%-46%] and 79% [95% CI, 77%-82%] at 75 years, respectively). Most tau PET–positive individuals (92%) were also Aβ PET positive. Cognitively unimpaired participants who were positive for both Aβ PET and tau PET had a higher absolute risk of progression to MCI or dementia over the following 5 years (57% [95% CI, 45%-71%]) compared with both Aβ PET–positive/tau PET–negative (17% [95% CI, 13%-22%]) and Aβ PET–negative/tau PET–negative (6% [95% CI, 5%-8%]) individuals. Among participants with MCI at the time of the tau PET scan, an Aβ PET–positive/tau PET–positive profile was associated with a 5-year absolute risk of progression to dementia of 70% (95% CI, 59%-81%). Conclusions and Relevance In a large convenience sample, a positive tau PET scan occurred at a nonnegligible rate among cognitively unimpaired individuals, and the combination of Aβ PET positivity and tau PET positivity was associated with a high risk of clinical progression in both preclinical and symptomatic stages of AD. These findings underscore the potential of tau PET as a biomarker for staging AD pathology.

Abstract This review explores the pivotal role of preanalytical variables in bringing liquid biopsy approaches into the clinic for brain tumors. Preanalytical variables encompass a range of critical issues, from blood sample collection and handling to the impact of tumor heterogeneity and patient-specific factors. These variables introduce challenges such as false positives, false negatives, and variability in the analysis of tumor signals, which can hinder the diagnostic and prognostic utility of liquid biopsies. Understanding the nuances of preanalytical variables is essential for the successful implementation of liquid biopsy in clinical settings. This paper delves into strategies aimed at mitigating the influence of preanalytical variables by emphasizing the importance of standardized sample collection protocols, optimized sample processing and storage, quality control measures, and the integration of multiple liquid biopsy modalities.

Objective To compare the efficacy of abatacept to placebo for the treatment of relapsing, nonsevere granulomatosis with polyangiitis (GPA). Methods In this multicenter trial, eligible patients with relapsing, nonsevere GPA were randomized to receive abatacept 125 mg subcutaneously once a week or placebo, both together with prednisone 30 mg/day (or equivalent), tapered and discontinued at week 12. Patients already taking methotrexate, azathioprine, mycophenolate, or leflunomide continued this medication at a stable dose. Patients achieving remission remained on their randomized assignment until relapse, early termination, or the common close date 12 months after enrollment of the last patient. Those who had a nonsevere relapse, had nonsevere worsening, or were not in remission by month 6 had the option to receive open‐label abatacept. The primary end point was the rate of treatment failure, defined as relapse, disease worsening, or failure to achieve a Birmingham Vasculitis Activity Score for Wegener's Granulomatosis (BVAS/WG) of 0 or 1 by six months. Results Sixty‐five patients were randomized; 34 received abatacept and 31 received placebo. No statistical difference in the treatment failure rate was found between those who received abatacept and those who received placebo ( P = 0.853). Treatment with abatacept did not demonstrate any statistical difference from placebo in key secondary end points, including time to full remission (BVAS/WG = 0), duration of glucocorticoid‐free remission, relapse severity, prevention of damage, and patient‐reported quality‐of‐life outcomes. There was no difference in the frequency or severity of adverse events between treatment arms, including infection. Conclusion In patients with relapsing, nonsevere GPA, abatacept did not reduce the risk of relapse, severe worsening, or failure to achieve remission.

ABSTRACTObjectivesTo achieve consensus among expert laser surgeons on standards for the prevention and management of adverse events from fully ablative laser resurfacing of the face.Materials and MethodsDelphi study with two rounds of ratings and revisions until consensus was achieved. The draft set of statements was developed by a steering committee based on expert clinical experience. This was followed by two rounds of rating and revisions completed by an expert panel, then a virtual consensus meeting. In both rounds, respondents rated the draft statements on a 9‐point Likert scale (1 = strongly disagree; 9 = strongly agree) and optionally provided comments. The consensus meeting was supplemented by the results of a systematic review of the literature (from 2000 to 2023).ResultsTwo rounds of Delphi survey were completed by 34 participants across four countries. Represented specialties were dermatology, facial plastic surgery, plastic surgery, and oculoplastic surgery. The initial 105 statements from round 1 expanded to 112 in round 2, with 96 statements achieving consensus. These included possible adverse events (11 statements); absolute and relative contraindications to treatment (5 statements); preoperative care and antimicrobial prophylaxis precautions (16 statements); intraoperative precautions (17 statements); postoperative care (21 statements); monitoring for and management of infection (16 statements); management of pigmentation changes (6 statements); and management of scarring and incipient scarring (4 statements).ConclusionAn international consensus statement was developed for the prevention and management of complications associated with fully ablative laser resurfacing of the face. While expert practices vary, key factors for optimizing outcomes include careful patient selection, counseling, and meticulous pre‐ and postoperative care. Further research will improve our understanding of this treatment technique.

Background Given the low haemorrhagic risk of intracranial low-grade dural arteriovenous fistulas (dAVFs), the benefits of routine intervention remain controversial. This study compares patient outcomes treated with stereotactic radiosurgery (SRS) versus conservative management. Method Multicentre retrospective analysis of the Consortium for Dural Arteriovenous Fistula Outcomes Research and the International Radiosurgery Research Foundation data. Inclusion criteria were (1) intracranial low-grade dAVF diagnosed by catheter-based angiography, (2) no prior dAVF-related haemorrhage and (3) management with upfront SRS (intervention group) or conservative management (observation group). The primary outcome was symptomatic improvement. Secondary outcomes included dAVF obliteration, up-conversion, haemorrhage, improvement and favourable modified Rankin Scale (mRS) at follow-up. Results 304 patients with a mean age of 56 years (SD 13.5) and a follow-up of 46.7 months (SD 45.5) were included. 135 (44.4%) were managed conservatively and 169 (55.6%) had upfront SRS. Compared with the observation group, symptomatic and mRS Score improvement (≥1-point decrease in baseline score) was more likely in the intervention group (95.1% vs 58.5%; OR=13.75 (5.61–33.69) and 37.0% vs 24.0%; OR=1.85 (1.09–3.15), respectively). These findings remained significant after multiple imputation and propensity score matching. Remaining outcomes were similar between groups. The all-cause mortality rate was 5.4% (n=16), unrelated to the dAVF or treatment. Five (3.0%) SRS-related complications were reported and resolved during the follow-up period. Conclusions SRS was associated with increased symptomatic and mRS Score improvement for low-grade dAVFs compared with conservative management. SRS had a low complication risk and did not appear to alter dAVF obliteration or haemorrhage. Future prospective trials on SRS as a first-line intervention for symptomatic low-grade dAVFs should be considered.

Cancer cachexia is a multifactorial syndrome involving muscle and fat wasting, inflammation, and metabolic dysfunction. Across cancer subtypes, pancreatic cancer has one of the highest cachexia incidence rates at ∼80%. Given the advanced age of most pancreatic cancer patients, we sought to query cancer-associated muscle wasting using an age-matched murine model. We found that histamine and histamine decarboxylase (HDC) activity were specifically elevated in the muscles of aged tumor-bearing mice. We further found that (1) wasting stimuli induced histamine production and enhanced HDC activity; (2) exogenous histamine was sufficient to induce atrophy-associated gene expression; (3) inhibition of HDC activity by α-fluoromethylhistidine (FMH) protected against atrophy; (4) treatment of tumor-bearing mice with FMH rescued muscle wasting; and (5) a calcineurin inhibitor was able to rescue histamine-associated increases in calcium/atrogene signaling. In summary, we present a novel metabolic pathway that has significant implications for the treatment of cachectic cancer patients.