Search Results (8,541)

Background/Objectives: Environmental stressors, including spaceflight and altered gravity, can negatively affect the symbiotic relationship between the gut microbiome and host health. Dietary prebiotics, which alter components of the gut microbiome, show promise as an effective way to mitigate the negative impacts of stressor exposure. It remains unknown, however, if the stress-protective effects of consuming dietary prebiotics will extend to chronic altered-gravity exposure. Methods: Forty female C57BL/6 mice consumed either a control diet or a prebiotic diet containing galactooligosaccharides (GOS) and polydextrose (PDX) for 4 weeks, after which half of the mice were exposed to 3 times the gravitational force of Earth (3g) for an additional 4 weeks. Fecal microbiome samples were collected weekly for 8 weeks, sequenced, and analyzed using 16S rRNA gene sequencing. Terminal physiological endpoints, including immune and red blood cell characteristics, were collected at the end of the study. Results: The results demonstrate that dietary prebiotic consumption altered the gut microbial community structure through changes to β-diversity and multiple genera across time. In addition, consuming dietary prebiotics reduced the neutrophil-to-lymphocyte ratio (NLR) and increased red blood cell distribution width (RDW-CV). Importantly, the prebiotic diet prevented the impacts of altered-gravity on β-diversity and the bloom of problematic genera, such as Clostridium_sensu_stricto_1 and Turicibacter. Furthermore, several prebiotic diet-induced genera-level changes were significantly associated with several host physiological changes induced by 3g exposure. Conclusions: These data demonstrate that the stress-protective potential of consuming dietary prebiotics extends to environmental stressors such as altered gravity, and, potentially, spaceflight. Full article

This research investigates topic-based sentiment classification in Greek educational-related data using transformer-based language models. A comparative evaluation is conducted on GreekBERT, XLM-r-Greek, mBERT, and Palobert using three original sentiment-annotated datasets representing parents of students with functional diversity, school directors, and teachers, each capturing diverse educational perspectives. The analysis examines both overall sentiment performance and topic-specific evaluations across four thematic classes: (i) Material and Technical Conditions, (ii) Educational Dimension, (iii) Psychological/Emotional Dimension, and (iv) Learning Difficulties and Emergency Remote Teaching. Results indicate that GreekBERT consistently outperforms other models, achieving the highest overall F1 score (0.91), particularly excelling in negative sentiment detection (F1 = 0.95) and showing robust performance for positive sentiment classification. The Psychological/Emotional Dimension emerged as the most reliably classified category, with GreekBERT and mBERT demonstrating notably high accuracy and F1 scores. Conversely, Learning Difficulties and Emergency Remote Teaching presented significant classification challenges, especially for Palobert. This study contributes significantly to the field of sentiment analysis with Greek-language data by introducing original annotated datasets, pioneering the application of topic-based sentiment analysis within the Greek educational context, and offering a comparative evaluation of transformer models. Additionally, it highlights the superior performance of Greek-pretrained models in capturing emotional detail, and provides empirical evidence of the negative emotional responses toward Emergency Remote Teaching. Full article

Background/Objectives: The liver, the body’s primary detoxifying organ, is often affected by various inflammatory diseases, including hepatitis, cirrhosis, and non-alcoholic fatty liver disease (NAFLD), many of which can be exacerbated by secondary infections such as spontaneous bacterial peritonitis, bacteremia, and sepsis—particularly in patients with advanced liver dysfunction. The global rise in these conditions underscores the need for effective interventions. Natural products have attracted attention for their potential to support liver health, particularly through synergistic combinations of plant extracts. Epavin, a dietary supplement from Erbenobili S.r.l., formulated with plant extracts like Taraxacum officinale (L.), Silybum marianum (L.) Gaertn., and Cynara scolymus (L.), known for their liver-supporting properties, has been proposed as adjuvant for liver functions. The aim of this work was to evaluate of Epavin’s antioxidant, anti-inflammatory, and protective effects against heavy metal-induced toxicity. In addition, the antibacterial effect of Epavin against a panel of bacterial strains responsible for infections associated with liver injuries has been evaluated. Methods: The protection against oxidative stress induced by H₂O₂ was evaluated in HepG2 and BALB/3T3 cells using the dichlorofluorescein diacetate (DCFH-DA) assay. Its anti-inflammatory activity was investigated by measuring the reduction in nitric oxide (NO) production in LPS-stimulated RAW 264.7 macrophages using the Griess assay. Additionally, the cytoprotecting of Epavin against heavy metal-induced toxicity and oxidative stress were evaluated in HepG2 cells using the [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide] (MTT) and DCFH-DA assays. The antibacterial activity of Epavin was assessed by determining the minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) against Gram-positive (Enterococcus faecalis ATCC 29212, and BS, Staphylococcus aureus 25923, 29213, 43300, and BS) and Gram-negative (Escherichia coli 25922, and BS, Klebsiella pneumoniae 13883, 70063, and BS) bacterial strains using the microdilution method in broth, following the Clinical and Laboratory Standards Institute’s (CLSI) guidelines. Results: Epavin effectively reduced oxidative stress in HepG2 and BALB/3T3 cells and decreased NO production in LPS-stimulated RAW 264.7 macrophages. Moreover, Epavin demonstrated a protective effect against heavy metal-induced toxicity and oxidative damage in HepG2 cells. Finally, it exhibited significant antibacterial activity against both Gram-positive and Gram-negative bacterial strains, with MIC values ranging from 1.5 to 6.0 mg/mL. Conclusions: The interesting results obtained suggest that Epavin may serve as a valuable natural adjuvant for liver health by enhancing detoxification processes, reducing inflammation, and exerting antibacterial effects that could be beneficial in the context of liver-associated infections. Full article

As a type of distinctive pit on Mars, skylights are entrances to subsurface lava caves. They are very important for studying volcanic activity and potential preserved water ice, and are also considered as potential sites for human extraterrestrial bases in the future. Most skylights are manually identified, which has low efficiency and is highly subjective. Although deep learning methods have recently been used to identify skylights, they face challenges of few effective samples and low identification accuracy. In this article, 151 positive samples and 920 negative samples based on the MRO-HiRISE image data was used to create an initial skylight dataset, which contained few positive samples. To augment the initial dataset, StyleGAN2-ADA was selected to synthesize some positive samples and generated an augmented dataset with 896 samples. On the basis of the augmented skylight dataset, we proposed YOLOv9-Skylight for skylight identification by incorporating Inner-EIoU loss and DySample to enhance localization accuracy and feature extracting ability. Compared with YOLOv9, the P, R, and the F1 of YOLOv9-Skylight were improved by about 9.1%, 2.8%, and 5.6%, respectively. Compared with other mainstream models such as YOLOv5, YOLOv10, Faster R-CNN, Mask R-CNN, and DETR, YOLOv9-Skylight achieved the highest accuracy (F1 = 92.5%), which shows a strong performance in skylight identification. Full article

In dogs with intervertebral disc extrusion (IVDE), the Glasgow Composite Measure Pain Scale—Short Form (GCMPS) and the Sharp and Wheeler Grading Scale (SWGS) are routinely used in the evaluation of pain (GCMPS) and neurological function (SWGS). Additionally, quantitative sensory tests (QSTs) are increasingly being incorporated into veterinary clinical practice for pain characterisation. The aim was to investigate a possible relationship between the GCMPS, the SWGS, and mechanical thresholds (MTs) in 31 client-owned dogs with thoracolumbar IVDEs. Dogs were always assessed in the same order, starting with pain rating using the GCMPS, followed by classifying neurological severity using the SWGS, before determining MTs using a handheld pressure algometer. Dogs were evaluated over a five-day testing period (before surgery and on days one, two, three, and ten after surgery). The GCMPS and the SWGS data remained consistent across all days of testing. No statistically significant correlation or difference was observed between the scores. MTs showed a significant negative correlation with the GCMPS (r = −0.311; p < 0.001) and a positive one with the SWGS (r = 0.282; p = 0.002). The GCMPS and MTs showed a slight divergence in their progression. MTs might be more sensitive than GCMPS in reflecting clinical improvement and should be considered for clinical practice. Full article

Background/Objectives: Prostate cancer (PCa) remains a major global health issue, associated with significant mortality and morbidity. Despite advances in diagnosis and treatment, predicting biochemical recurrence (BCR) after radical prostatectomy remains challenging, highlighting the need for reliable biomarkers to guide prognosis and therapy. The study aimed to evaluate the prognostic significance of the PTEN and ERG biomarkers in predicting BCR and tumor progression in PCa patients who underwent radical prostatectomy. Methods: This study consisted of a cohort of 91 patients with localized PCa who underwent radical prostatectomy between 2016 and 2022. From this cohort, 77 patients were selected for final analysis. Tissue microarrays (TMAs) were constructed from paraffin blocks, and immunohistochemical (IHC) staining for PTEN and ERG was performed using specific antibodies on the Ventana BenchMark ULTRA system (Roche Diagnostics, Indianapolis, IN, USA). Stained sections were evaluated and correlated with clinical and pathological data. Results: PTEN expression showed a significant negative correlation with BCR (r = −0.301, p = 0.014), indicating that reduced PTEN expression is associated with increased recurrence risk. PTEN was not significantly linked to PSA levels, tumor stage, or lymph node involvement. ERG expression correlated positively with advanced pathological tumor stage (r = 0.315, p = 0.005) but was not associated with BCR or other clinical parameters. Conclusions: PTEN appears to be a valuable prognostic marker for recurrence in PCa, while ERG may indicate tumor progression. These findings support the potential integration of PTEN and ERG into clinical practice to enhance risk stratification and personalized treatment, warranting further validation in larger patient cohorts. Full article

This study investigated the effects of reduced nitrogen combined with an organic fertilizer on maize yield, soil microbial communities, and enzyme activities to optimize fertilization strategies. A field experiment on cinnamon soil in Yuncheng, Shanxi, was conducted and included six treatments: no fertilizer (CK), conventional N (NC0, 180 kg N/ha), sole organic fertilizer (CN0, 3000 kg/ha), and reduced-N + organic fertilizer (CN1: 90 kg N/ha + 3000 kg/ha; CN2: 135 kg N/ha + 3000 kg/ha; and CN3: 180 kg N/ha + 3000 kg/ha). We analyzed yield components, soil nutrients, urease and invertase activities, and bacterial community structure (16S rRNA sequencing). The key results are as follows: CN1 achieved the highest yield (9764.87 kg/ha), which was 46.8% higher than CK. CN2 maintained comparable yields while delivering higher enzyme activities and microbial abundance, positioning this strategy as suitable for soil remediation. Co-application enriched two beneficial phyla, Proteobacteria and Planctomycetota (19% in CN2), with Proteobacteria positively correlating with urease activity and alkali-hydrolyzable N (p < 0.05), while Verrucomicrobiota negatively correlated with urease activity. In conclusion, 25–50% N reduction with an organic fertilizer (3000 kg/ha) synergistically enhances yield, soil enzymes, and beneficial microbiota, supporting sustainable high-yield agriculture with improved soil fertility. Full article

Background: Anhedonia, defined as the diminished capacity to experience pleasure, represents a core negative symptom in first-episode psychosis (FEP) with profound implications for functional outcomes and long-term prognosis. Despite its clinical significance, comprehensive understanding of anhedonia prevalence, underlying mechanisms, and optimal intervention strategies in early psychosis remains limited. Objectives: To systematically examine the prevalence and characteristics of anhedonia in FEP patients, explore neurobiological mechanisms, identify clinical correlates and predictive factors, and evaluate intervention efficacy. Methods: Following PRISMA 2020 guidelines, we conducted comprehensive searches across PubMed, Embase, PsycINFO, and Web of Science databases from January 1990 to June 2025. Studies examining anhedonia and negative symptoms in FEP patients (≤24 months from onset) using validated assessment instruments were included. Quality assessment was performed using appropriate tools for study design. Results: Twenty-one studies comprising 3847 FEP patients met inclusion criteria. Anhedonia prevalence ranged from 30% at 10-year follow-up to 53% during acute phases, demonstrating persistent motivational deficits across illness trajectory. Factor analytic studies consistently supported five-factor negative symptom models with anhedonia as a discrete dimension. Neuroimaging investigations revealed consistent alterations in reward processing circuits, including ventral striatum hypofunction and altered network connectivity patterns. Social anhedonia demonstrated stronger associations with functional outcomes compared to other domains. Epigenetic mechanisms involving oxytocin receptor methylation showed gender-specific associations with anhedonia severity. Conventional antipsychotic treatments showed limited efficacy for anhedonia improvement, while targeted psychosocial interventions demonstrated preliminary promise. Conclusions: Anhedonia showed high prevalence (30–53%) across FEP populations with substantial clinical burden (13-fold increased odds vs. general population). Meta-analysis revealed large effect sizes for anhedonia severity in FEP vs. controls (d = 0.83) and strong negative correlations with functional outcomes (r =·−0.82). Neuroimaging demonstrated consistent ventral striatum dysfunction and altered network connectivity. Social anhedonia emerged as the strongest predictor of functional outcomes, with independent suicide risk associations. Conventional antipsychotics showed limited efficacy, while behavioral activation approaches demonstrated preliminary promise. These findings support anhedonia as a distinct treatment target requiring specialized assessment and intervention protocols in early psychosis care. Full article

Background and Objectives: A thorough comprehension of the essential molecules and related processes underlying the carcinogenesis, proliferation, and recurrence of acute myeloid leukemia (AML) is crucial. This study aimed to investigate the expression levels, diagnostic and prognostic significance and biological roles of Bcl-2-associated athanogene 4 (BAG4) in AML carcinogenesis. Materials and Methods: Gene expression profiles were analyzed using publicly available datasets, particularly GSE9476 and TCGA, using tools such as GEO2R, GEPIA2, UALCAN and TIMER2.0. The immune infiltration correlation was examined using the GSCA platform, while the function of BAG4 at the single-cell level was analyzed via CancerSEA. Protein–protein and gene–gene interaction networks were constructed using STRING and GeneMANIA, and enrichment analyses were performed using GO, KEGG and DAVID. Expression validation was performed using RT-qPCR in HL-60 (AML) and HaCaT (normal) cells, and ROC curve analysis evaluated the diagnostic accuracy. Results: BAG4 was significantly overexpressed in AML tissues and cell lines compared with healthy controls. High BAG4 expression was associated with poor overall survival and strong diagnostic power (AUC = 0.944). BAG4 was positively associated with immune cell infiltration and negatively associated with CD4+/CD8+ T and NK cells. At the single-cell level, BAG4 was associated with proliferation, invasion, and DNA repair functions. Functional network analysis showed that BAG4 interacted with apoptosis and necroptosis-related genes such as BCL2, BAG3 and TNFRSF1A and was enriched in pathways such as NF-κB, TNF signaling and apoptosis. Conclusions: BAG4 is overexpressed in AML and is associated with adverse clinical outcomes and immune modulation. It may play an important role in leukemogenesis by affecting apoptotic resistance and immune evasion. BAG4 has potential as a diagnostic biomarker and treatment target in AML, but further in vivo and clinical validation is needed. Full article

Background/Objectives: Swine influenza A virus (swIAV), a prevalent respiratory pathogen in porcine populations, poses substantial economic losses to global livestock industries and represents a potential threat to public health security. Neuraminidase (NA) has been proposed as an important component for universal influenza vaccine development. NA has potential advantages as a vaccine antigen in providing cross-protection, with specific antibodies that have a broad binding capacity for heterologous viruses. In this study, we evaluated the immunogenicity and protective efficacy of a tetrameric recombinant NA subunit vaccine in a swine model. Methods: We constructed and expressed structurally stable soluble tetrameric recombinant NA (rNA) and prepared subunit vaccines by mixing with ISA 201 VG adjuvant. The protective efficacy of rNA-ISA 201 VG was compared to that of a commercial whole inactivated virus vaccine. Pigs received a prime-boost immunization (14-day interval) followed by homologous viral challenge 14 days post-boost. Results: Both rNA-ISA 201 VG and commercial vaccine stimulated robust humoral responses. Notably, the commercial vaccine group exhibited high viral-binding antibody titers but very weak NA-specific antibodies, whereas rNA-ISA 201 VG immunization elicited high NA-specific antibody titers alongside substantial viral-binding antibodies. Post-challenge, both immunization with rNA-ISA 201 VG and the commercial vaccine were effective in inhibiting viral replication, reducing viral load in porcine respiratory tissues, and effectively mitigating virus-induced histopathological damage, as compared to the PBS negative control. Conclusions: These findings found that the anti-NA immune response generated by rNA-ISA 201 VG vaccination provided protection comparable to that of a commercial inactivated vaccine that primarily induces an anti-HA response. Given that the data are derived from one pig per group, there is a requisite to increase the sample size for more in-depth validation. This work establishes a novel strategy for developing next-generation SIV subunit vaccines leveraging NA as a key immunogen. Full article

Background: The most common female endocrinopathy is polycystic ovary syndrome (PCOS), affecting 10–20% of women of reproductive age. It is associated with a wide range of hormonal and biochemical abnormalities and long-term metabolic and cardiovascular risks. It is characterized by infertility due to chronic anovulation, hyperandrogenism, polycystic ovarian morphology, and is often associated with insulin resistance (IR) and obesity. Hyperinsulinemia further increases androgen production and reduces sex hormone-binding globulin (SHBG) levels, thereby aggravating symptoms. In addition, vitamin D deficiency is often present in PCOS patients, and increasing evidence suggests that it may also be associated with insulin resistance and hyperandrogenism. Objective: This study aimed to evaluate the relationships between insulin resistance, vitamin D deficiency, body mass index (BMI), and androgen levels in women with PCOS. Method: A cross-sectional study was conducted in which data from 195 women diagnosed with PCOS and not yet receiving therapy at a gynecologic endocrinology unit of a university-based tertiary clinical center, between 2019 and 2024, were analyzed. The parameters recorded were age, body mass index (BMI), 25(OH) vitamin D levels, androgen hormone levels (testosterone, androstenedione), glucose-insulin responses during a 3-point oral glucose tolerance test (OGTT). Statistical analyses, including linear regression, Pearson, and Spearman correlation tests were used to assess associations between variables. Results: The mean age of the patients was 24.8 years (18–42), and the mean BMI was 30.6 kg/m² (17–51). Vitamin D deficiency was observed in 84.1% of patients, hyperandrogenism in 45.8%, and insulin resistance in 44.5%. A significant inverse correlation was found between BMI and vitamin D levels (r = −0.31, p =< 0.01) indicating that higher BMI is associated with lower vitamin D status. Similarly, BMI also showed a significant negative correlation with SHBG levels (r = –0.45, p < 0.01), suggesting that increasing body weight is linked to reduced SHBG concentrations. In addition, BMI was significantly positively correlated with 2 h insulin levels (r = 0.43, p =< 0.01) and with testosterone levels (r = 0.21, p = 0.01). These findings suggest that increased adiposity intensifies insulin resistance and is linked to both vitamin D deficiency and elevated androgen levels. Moreover, the combination of hyperinsulinemia and low vitamin D further disrupts hormonal balance by promoting ovarian androgen production and decreasing SHBG levels, thereby increasing the bioavailability of testosterone. A significant inverse correlation was found between vitamin D levels and 2 h insulin levels (r = −0.28, p =< 0.01), indicating that lower vitamin D status is associated with increased insulin resistance. Furthermore, 2 h insulin levels showed a significant positive correlation with testosterone levels (r = 0.32, p =< 0.01), suggesting that greater insulin resistance is linked to higher androgen production. Additionally, vitamin D levels were inversely correlated with testosterone (r = −0.18, p = 0.02), demonstrating that a lower vitamin D status may further contribute to the hyperandrogenic environment. Vitamin D levels also showed a significant positive correlation with SHBG concentrations (r = 0.29, p < 0.01), indicating that a higher vitamin D status may be associated with increased SHBG levels. In contrast, 2 h insulin levels were inversely correlated with SHBG (r = −0.43, p < 0.01), reflecting the suppressive effect of hyperinsulinemia on SHBG production. Conclusions: Insulin resistance, BMI, and vitamin D deficiency are closely related to each other and to the severity of PCOS, which is confirmed by the correlations with androgen levels. The revealed relationships draw attention to the special importance of vitamin D supplementation and the correction of carbohydrate metabolism in alleviating the symptoms of the disease and reducing long-term health risks. Full article

Background and Objectives: Nicotine is the most well-studied toxic substance in cigarette smoke and e-cigarette vape. However, smoke and vape are composed of other components that have a negative impact on health. The objective of this study is to investigate whether nicotine has a distinctive impact on molecular mechanisms in stem cells. Methods: The cellular impact of nicotine on the regenerative capacity of human dental pulp stem cells (DPSCs) and the microRNA (miRNA) profile was examined. Bioinformatic analysis was performed to identify miRNA-regulated cellular pathways associated with nicotine exposure. These pathways were then compared to those induced by cigarette smoke condensate (CSC). Results: Prolonged exposure to nicotine significantly impaired the regeneration of DPSCs and changed the expression of miRNAs. Nicotine upregulated the expression of hsa-miR-7977, hsa-miR-3178, and hsa-miR-10400-5p compared to vehicle control. Interestingly, nicotine did not change the expression of hsa-miR-29b-3p, hsa-miR-199b-5p, hsa-miR-26b-5p, or hsa-miR-26a-5p compared to the control. However, the expressions of these miRNAs were significantly altered when compared to CSC treatment. Further analysis revealed that nicotine was distinctively associated with certain miRNA-targeted pathways including apoptosis, ErbB, MAPK signaling, PI3K-Akt, TGF-b signaling, and Wnt signaling. Conclusions: Our work provides evidence on the distinctive miRNA signature induced by nicotine. The information will be important for identifying the unique molecular pathways downstream of nicotine from smoking and vaping in different individuals, providing a new direction for personalized disease prevention, prognosis, and treatment. Full article

Background and Objectives: Orthodontic treatment aims to enhance dental aesthetics and function, yet many patients report dissatisfaction. This study was designed with the following objectives: To assess overall patient satisfaction during active orthodontic treatment; to identify key psychosocial and clinical predictors of satisfaction, including self-confidence, social experiences, and cost perception; to evaluate the impact of orthodontist–patient communication on satisfaction and perceived treatment outcomes; to explore the relationship between aesthetic improvement and willingness to undergo treatment again. Materials and Methods: A cross-sectional survey was conducted using structured questionnaires to assess satisfaction, pain perception, treatment expectations, and communication quality. Statistical analyses, including correlations and regression models, were used to identify predictors of satisfaction. The study included 450 orthodontic patients from the north-eastern region of Romania, undergoing active treatment at the time of data collection. Results: The strongest predictor of satisfaction was improved self-confidence and smile aesthetics (r = 0.62). Effective communication with orthodontists significantly increased satisfaction (r = 0.58, p = 0.002), while perceived high costs had a negative impact (r = −0.41). Pain and discomfort were common, with 90% of patients experiencing treatment-related pain, leading to reduced compliance. Social embarrassment due to braces also contributed to dissatisfaction (r = −0.47). Conclusions: Patient satisfaction with orthodontic treatment is primarily influenced by aesthetic improvements and effective communication. While enhanced smile perception boosts confidence, financial concerns and social discomfort may negatively affect the overall experience. Improving accessibility to treatment and providing comprehensive patient support are essential for optimizing patient satisfaction. Full article

Aquaculture is a key food production sector responsible for meeting the nutritional needs of a rapidly growing global population. However, the emergence of disease outbreaks has become a major challenge for the aquaculture industry, resulting in significant economic losses. The use of costly and toxic antibiotics for treatment has a negative impact on the aquatic environment. Consequently, there has been a growing interest in probiotics as a non-antibiotic approach to manage disease outbreaks and improve fish performance. The use of the yeast Saccharomyces cerevisiae (SC) has shown remarkable benefits in aquaculture. In February 2025, a systematic search was conducted based on the Web of Science (WoS) database for the period 2015–2025 to identify relevant studies investigating the beneficial effects of SC in aquaculture. After searching on WoS, 466 documents were found and analyzed using R-bibliometric package for comprehensive analysis to identify research gap, trends, and distribution of global literature that focuses on SC in aquaculture. The most relevant and recent articles were reviewed, summarized and discussed. The yeast SC have shown a wide range of benefits, including improved growth performance, feed efficiency, enhanced diversity of the gut microbiome and immune response. The implementation of SC is becoming a recent trend and its efficacy in aquatic environments has been thoroughly investigated. This review aims to provide a valuable insight into SC as one of the most important aquaculture probiotics. It also emphasizes the need for further research to fully understand its benefits and the way it works. Full article

Objectives: This study aimed to investigate both the linear and non-linear associations between serum 25-hydroxyvitamin D [25(OH)D] levels and serum uric acid concentrations in Korean adults, with a particular focus on the vitamin D-insufficient range (<30 ng/mL), and to explore the potential metabolic implications of this relationship. Methods: Using data from the Korea National Health and Nutrition Examination Survey (KNHANES), we analyzed 10,864 adults aged 19 years and older. Serum vitamin D levels were categorized into quartiles (Q1–Q4), and their relationships with uric acid concentrations were examined using Pearson correlation, analysis of variance (ANOVA), and restricted cubic spline regression. Multivariate models were adjusted for potential confounders including age, sex, body mass index (BMI), kidney function, chronic disease status, and macronutrient intake. Results: In unadjusted analysis, a statistically significant but weak negative correlation was observed between serum 25(OH)D and uric acid levels (Pearson’s r = −0.092, p < 0.001). However, in multivariate regression adjusting for confounders, a weak positive association emerged. Restricted cubic spline analysis revealed significant positive associations in the lower quartiles (Q1–Q3), with the strongest association in Q3 (β = 0.769, 95% CI: 0.34–1.19, p < 0.001). No significant association was observed in the highest quartile (Q4). Conclusions: Serum vitamin D and uric acid concentrations show a non-linear relationship, with a significant positive association within the vitamin D-insufficient range (<30 ng/mL). These findings provide new insights into the potential metabolic role of vitamin D and highlight the need for longitudinal and interventional studies to clarify causality and clinical significance. Full article