San Sebastián University

• Median nerve variants within the carpal tunnel have a pooled prevalence of 12%. • Bifid median nerve is the most frequently reported morphological variant. • No consistent association was found between anatomical variants and carpal tunnel syndrome. • Coexisting vascular or muscular anomalies may influence surgical complexity. • Preoperative imaging may aid anatomical identification, although clinical benefit remains uncertain. Anatomical variants of the median nerve (MN) within the carpal tunnel are clinically relevant due to their potential impact on the development, diagnosis, and surgical management of carpal tunnel syndrome (CTS). Reported prevalence estimates vary considerably across populations and study designs. To systematically review the literature and estimate the pooled prevalence of morphological variants of the median nerve within the carpal tunnel, and to assess their laterality, geographic distribution, and reported clinical implications. A systematic review and meta-analysis were conducted in accordance with PRISMA 2020 guidelines. MEDLINE, Scopus, Web of Science, CINAHL, and LILACS were searched from inception to November 2024. Google Scholar was used for supplementary screening of gray literature. Observational studies reporting the prevalence of MN variants identified through imaging, surgical exploration, or anatomical dissection were included. Methodological quality was assessed using the Anatomical Quality Assessment (AQUA) tool. Pooled prevalence estimates were calculated using a random-effects model (DerSimonian–Laird) with Freeman–Tukey double arcsine transformation. Sixty-three studies met eligibility criteria for qualitative synthesis, and 19 studies (n = 9,045 subjects) were included in the primary meta-analysis. The pooled prevalence of MN variants within the carpal tunnel was 12% (95% CI: 9–15%), with substantial heterogeneity (I² = 87%). Subgroup analysis showed similar prevalence in imaging-based studies (12%, 95% CI: 9–15%; I² = 87.8%). No clear laterality predominance was observed (right: 46%, 95% CI: 40–52%; I² = 0.0%; left: 53%, 95% CI: 48–59%; I² = 0.0%), whereas bilateral presentation demonstrated greater variability (21%, 95% CI: 6–36%; I² = 90.6%). Geographic subgroup analysis showed pooled prevalence estimates of 22% in Asia (95% CI: 13–31%; I² = 92.6%), 20% in Europe (95% CI: 14–27%; I² = 79.2%), and 18% in America (95% CI: 16–20%; I² = 19.4%). Morphological variants of the median nerve within the carpal tunnel are relatively common anatomical findings. Current evidence does not support their role as independent risk factors for CTS; however, their coexistence with vascular or muscular anomalies may influence local anatomical relationships and surgical complexity. Preoperative imaging may facilitate anatomical identification and surgical planning, although its impact on clinical outcomes and intraoperative complications remains uncertain and requires further prospective investigation.

Propolis is a chemically complex natural product with recognized antioxidant potential, but its compositional heterogeneity and poor aqueous solubility complicate formulation and interpretation of in vitro release behavior. In this study, a nanostructured lipid carrier (NLC) based on Gelucire® 44/14 was developed as a physicochemical platform to modulate the accessibility of a selected Chilean ethanolic propolis extract. Propolis extracts from different origins were first screened using complementary antioxidant assays (DPPH, ABTS, ORAC, FRAP), leading to the selection of the Peñaflor extract, which exhibited the highest phenolic content (~41 mg GAE/g) and antioxidant capacity. The selected extract was incorporated into NLCs with encapsulation efficiencies above 90%, a narrow size distribution (~200 nm), and high stability over 90 days. Under simple aqueous conditions, propolis release remained limited (<15% over 6 h), consistent with diffusion- and partition-controlled transport. In simulated gastrointestinal media containing bile components, pronounced pH- and composition-dependent effects were observed. While fed-state intestinal conditions induced extensive morphological remodeling without increasing the analytically accessible fraction (<3% at 4 h), fasted-state intestinal media promoted a higher accessible fraction (~14% within 1 h) without complete carrier disruption, as confirmed by transmission electron microscopy. Preliminary cytocompatibility studies in HepG2 cells showed acceptable viability at 10-40 µg/mL and concentration-dependent effects at higher doses. Overall, this work demonstrates that bile components modulate propolis accessibility through dynamic partitioning and colloidal reorganization rather than simple carrier breakdown, providing a physicochemical framework for future digestion and absorption studies.

The rapid digital transformation of education systems has profoundly changed teachers' working conditions, intensified administrative demands, and highlighted territorial and organizational inequalities. In this context, understanding how these dynamics influence teacher engagement is essential for promoting healthy educational organizations. This study examined the factor structure of the UWES-17 and analyzed the relationship between engagement levels and sociodemographic variables in a sample of 314 elementary school teachers from four regions of Chile. Descriptive analyses, exploratory factor analysis with polychoric correlations and unweighted least squares, and confirmatory factor analysis using robust ULS and the Hull method were performed. The results showed a robust two-factor structure-Inspired Vitality and Challenging Commitment-with excellent fit indices. Freeman-Halton exact tests showed that Inspired Vitality was significantly associated with age, gender, region, location, administrative dependency, and professional experience, while Challenging Commitment was associated with gender, region, context, and professional experience. These findings indicate that teacher engagement is influenced by both structural inequalities and individual trajectories. The results underscore the need to strengthen organizational resources, regulate digital intensification, and reduce territorial gaps to promote teacher well-being.

Oral health literacy (OHL) influences older adults' capacity to obtain, process and apply oral health information for self-care and decision-making. Evidence on OHL in community-dwelling older adults in Chile remains scarce. This study explored the factors shaping OHL among Chilean community-dwelling older adults. A qualitative exploratory study was conducted using the Grounded Theory approach. Older adults (≥ 65 years) were purposively sampled from three municipalities in Santiago, Chile, representing different levels of social vulnerability. Thirteen in-depth, face-to-face, semi-structured interviews were conducted. The interviews were audio-recorded, transcribed verbatim and analysed iteratively using constant comparison and open, axial and selective coding, categorising the answers to identify emerging topics until reaching saturation. Data triangulation included interviews, field observations and document reviews. Findings emerged into two overarching dimensions shaping OHL across the life course: upstream and downstream factors. Upstream factors included contextual factors, provider-related factors and system-related factors. Downstream factors encompassed individual and behavioural aspects that influenced access to dental care and attention. OHL in older adults is shaped by cumulative life-course experiences across structural, social and individual domains. Addressing OHL requires integrated public policies, professional training in patient-centred communication and community-based strategies targeting social determinants to promote equitable oral health in older age.

The data that support the findings of this study are available from the corresponding author upon reasonable request.