Search Results (1,618)

To investigate the molecular characteristics of H3N2 canine influenza viruses circulating in Jiangsu, China, we isolated a H3N2 strain (A/Canine/Nanjing/CnNj01-2025) from a dog presenting with respiratory signs at the Veterinary Teaching Hospital of Nanjing Agricultural University. All eight gene segments were sequenced and compared with those of two human H3N2 strains and five avian H3N2 strains. Antigenicity and receptor-binding properties were also assessed. Phylogenetic analysis revealed that the canine isolate descended from the avian lineage and formed an independent evolutionary clade, while the human strains were more distantly related to the avian lineage. Glycosylation analysis of the HA protein revealed that the canine strain carried seven N-glycosylation sites, including a unique site at residue 97/81 (HA/H3 numbering), which serves as a molecular signature of the canine strain. Several amino-acid substitutions were identified in major antigenic sites, including D97/81N, A176/160T, N204/188D, V212/196I, and W237/222L. Analysis of internal genes showed that the canine strain harbored PB2 292T and 590S mammalian adaptation mutations, which are also present in human strains. Hemagglutination inhibition (HI) assays of the canine strain indicated moderate serologic cross-reactivity with a human H3N2 antiserum (16-fold reduction), whereas avian strains showed no cross-reactivity. Receptor-binding assays demonstrated that the virus retained predominant α-2,3 sialic acid binding, comparable to that of avian influenza viruses, and gained a modest affinity for human-type α-2,6 sialic acid receptors. Therefore, the canine H3N2 virus has undergone significant antigenic drift, developed partial serological cross-reactivity with human strains, and acquired detectable but limited binding affinity for human-type receptors. Overall, our findings suggest that the current canine H3N2 influenza virus exhibits distinct genetic and antigenic variations from human and avian strains. Continuous molecular and serological surveillance of canine influenza viruses is therefore warranted to monitor their evolutionary trends and assess the potential for cross-species transmission. Full article

This study examines LEED certification strategies for Existing Buildings 4.1 (LEED-EB v4.1)-certified office projects in major US cities and their relationship with local green building policies. LEED-EB v4.1 is the latest program with an appropriate sample size to conduct significance tests and draw robust statistical inferences. LEED-EB v4.1 features six performance indicators: “transportation”, “water”, “energy”, “waste”, “indoor environmental quality (IEQ)”, and “overall LEED”. The purpose of this study was to evaluate LEED-EB v4.1 gold-certified office projects in San Francisco (SF), New York City (NYC), and Washington, D.C. (DC). Exact Wilcoxon–Mann–Whitney and Cliff’s δ tests were used to compare the same LEED variables between two cities. Pearson’s or Spearman’s correlation tests were used to assess the strength/direction between two LEED variables, and a simple linear regression (SLR) model was applied to predict the overall LEED variable. It was found that SF outperforms NYC in “IEQ” (δ = 0.53 and p = 0.009) and outperforms both NYC and DC in “overall LEED” (δ = 0.66 and p = 0.001; δ = 0.59 and p = 0.001). “Energy” and “waste” were positively and significantly correlated with “overall LEED” in NYC (r = 0.61 and p = 0.001; r = 0.40 and p = 0.044, respectively) and DC (r = 0.83 and p < 0.001; r = 0.65 and p = 0.009, respectively). The SLR results showed that one-point increases in “energy” and “waste” scores resulted in an increase in NYC’s overall LEED scores by approximately 0.78 and 1.72 points, respectively, and one-point increases in “energy” and “waste” scores resulted in an increase in DC’s overall LEED score by approximately 0.96 and 1.97 points, respectively. It is hypothesized that the difference in the “IEQ” of LEED-EB-certified office buildings between SF and NYC may be due to differences in these cities’ green building policies. According to the “overall LEED” indicator, office buildings in SF are more sustainable than those in NYC and DC. “Energy” and “waste” showed a stronger positive relationship with “overall LEED” in NYC and DC than the other indicators. However, the correlation analysis for SF presented in the Limitations Section is speculative due to the small sample size (n = 11). Full article

Tricalcium phosphate (TCP) bioceramics, available as α- and β-polymorphs, are frequently employed in the production of three-dimensionally (3D) printed bone scaffolds. Although hydrothermal immersion processing (HP) and sintering (S) are commonly adopted as post-printing techniques for bioceramics, a comprehensive comparative analysis of their effects on the osteogenic performance of α- and β-polymorphs in vivo remains inadequately investigated. In this study, α-TCP and β-TCP scaffolds were fabricated via direct ink writing and subjected to hydrothermal immersion processing (α-TCP/HP) and sintering (β-TCP/S) prior to implantation in n = 12 skeletally mature sheep (n = 1 scaffold per group per animal), and the outcome variables were evaluated at 3 and 12 weeks postoperatively (n = 6 sheep per time point). The quantitative results showed no significant differences in bone deposition or scaffold resorption at 3 weeks postoperatively (p = 0.618 and p = 0.898, respectively). However, at 12 weeks, there was a significant increase in osteogenesis and scaffold resorption in the β-TCP/S cohort relative to the α-TCP/HP counterparts (p < 0.001 and p = 0.004, respectively). β-TCP scaffolds subjected to post-print sintering exhibited superior osteoconductive and resorptive profiles compared to hydrothermal immersion-processed α-TCP scaffolds over the 12-week healing period. Full article

The increasing impact of global warming is predominantly driven by the extensive use of fossil fuels, which release significant amounts of greenhouse gases into the atmosphere. This has led to a critical need for alternative, sustainable energy sources that can mitigate environmental impacts. Photovoltaic technology has emerged as a promising solution by harnessing renewable energy from the sun, providing a clean and inexhaustible power source. Perovskite solar cells (PSCs) are a class of hybrid organic–inorganic solar cells that have recently attracted significant scientific attention due to their low cost, relatively high efficiency, low–temperature processing routes, and longer carrier lifetimes. These characteristics make them a viable alternative to traditional fossil fuels, reducing the carbon footprint and contributing to the fight against global warming. In this study, the SCAPS–1D numerical simulator was used in the computational analysis of a PSC device with the configuration FTO/ETL/BaZr(S_0.6Se_0.4)₃/HTL/Ir. Different hole transport layer (HTL) and electron transport layer (ETL) material were proposed and tested. The HTL materials included copper (I) oxide (Cu₂O), 2,2′,7,7′–Tetrakis(N,N–di–p–methoxyphenylamine)9,9′–spirobifluorene (spiro–OMETAD), and poly(3–hexylthiophene) (P₃HT), while the ETLs included cadmium suphide (CdS), zinc oxide (ZnO), and [6,6]–phenyl–C₆₁–butyric acid methyl ester (PCBM). Finally, BaZr(S_0.6Se_0.4)₃ was proposed as an absorber, and a fluorine–doped tin oxide glass substrate (FTO) was proposed as an anode. The metal back contact used was iridium. Photovoltaic parameters such as short circuit density (I_sc), open circuit voltage (V_oc), fill factor (FF), and power conversion efficiency (PCE) were used to evaluate the performance of the device. The initial simulated primary device with the configuration FTO/CdS/BaZr(S_0.6Se_0.4)₃/spiro–OMETAD/Ir gave a PCE of 5.75%. Upon testing different HTL materials, the best HTL was found to be Cu₂O, and the PCE improved to 9.91%. Thereafter, different ETLs were also inserted and tested, and the best ETL was established to be ZnO, with a PCE of 10.10%. Ultimately an optimized device with a configuration of FTO/ZnO/BaZr(S_0.6Se_0.4)₃/Cu₂O/Ir was achieved. The other photovoltaic parameters for the optimized device were as follows: FF = 31.93%, J_sc = 14.51 mA cm⁻², and V_oc = 2.18 V. The results of this study will promote the use of environmentally benign BaZr(S_0.6Se_0.4)₃–based absorber materials in PSCs for improved performance and commercialization. Full article

This numerical study investigates steady separated flow past a grooved circular cylinder within the Reynolds number range $7.5\le R{e}_D\le 30$, comprising variations in groove depth ($h$) and spacing ($\beta$). The groove width ($w$) is kept constant, while h/w varies across four levels ($0.5\le h/w\le 2$) and $\beta$ across five angles ($10°\le \beta \le 45°$). The results exhibit strong agreement with unbounded flow data, confirming blockage independence across the examined regime. Detailed analysis shows that $\beta$ has a stronger influence than $h/w$ on surface-pressure-dependent variables ($C_{p,0}$, $C_{p,b}$, $C_D$, ${\theta }_{sep}$) and wake-defining parameters ($L_w$, $W_w$, $\xi$, $\eta$), underscoring the dominant role of $\beta$ in rectilinear groove aerodynamics. In this regard, a critical spacing of $\beta =20°$ is observed, beyond which the sensitivity of the parameters toward the cylinder configuration decreases. Thus, significant flow control and drag reduction are attained for $R{e}_D=7.5$ at the lowest spacing $\beta =10°$, regardless of the groove’s $h/w$. Among these, the streamwise-oriented variables, $C_{p,0}$, $C_D$, $L_w$, $\xi$, and $u_{min}$, exhibit monotonic trend with respect to $\beta$ and are modeled using power-law relations. The models for $C_{p,0}$ and $C_D$ exhibit significant accuracy with $R^2\approx 0.999$ across all $\beta$ values considered, while it is 0.89–0.98 for $L_w$, $\xi$, and $u_{min}$, depending on $R{e}_D$. Transverse-oriented parameters ($W_w \mathrm{a}\mathrm{n}\mathrm{d} \eta$) vary non-monotonically. In addition, it is found that the streamwise locations of maximum wake width ($x_{w,max}$) and minimum velocity ($x_{u,min}$) are unaffected by the grooved cylinder configuration. Full article

N₂-fixing bacteria have great potential to be used as biofertilizer in agriculture to promote plant growth via nitrogen fixation. In this study, a novel species Fontibacillus forbon sp. nov., with strain BL-9^T as the type strain, was isolated from the rhizosphere of Fraxinus chinensis. Strain BL-9^T was able to fix nitrogen and grow on nitrogen-free medium. Phylogenetic analysis of 16S rRNA gene revealed that strain BL-9^T was most closely related to Fontibacillus phaseoli BAPVE7B (98.03%), followed by Fontibacillus solani A4STR04 (96.72%), Fontibacillus panacisegetis (96.6%), Paenibacillus vini (96.6%), and Paenibacillus segetis DB13260 (96.57%). The phylogenomic tree supported that strain BL-9^T was most closely related to F. phaseoli BAPVE7B. The digital DNA-DNA hybridization (dDDH) and average nucleotide identity (ANI) between strain BL-9^T and its closely related type strain, F. phaseoli BAPVE7B, were 42.5% and 90.94%, respectively, which were below the values (70% for dDDH and 95% for ANI) for species discrimination. The DNA G+C content of strain BL-9^T was 49.7%. The genome of strain BL-9^T had a nif (nitrogen fixation) gene cluster containing 10 genes (nifB nifH nifD nifK nifE nifN nifX orf1 hesA nifV). The predominant fatty acid was anteiso-C15:0, the major menaquinone was MK-7, and the major polar lipid was diphosphatidylglycerol. Strain BL-9^T and its closely related species of Fontibacillus had some common and distinguished physiological characteristics. Based on genomic, phylogenetic, chemotaxonomic, and phenotypic features, strain BL-9^T represents a novel species of the genus Fontibacillus. The name proposed for this species is Fontibacillus forbon sp. nov., with the type strain BL-9^T. Full article

Objectives: This study aims to investigate the potential relationship between low-level lead exposure and serum gamma-glutamyl transferase (GGT) concentrations, which may serve as a biomarker of oxidative stress in U.S. adolescents. Methods: We used NHANES data from 1999 to 2000 to 2017–2018. Analyses were limited to adolescents aged 12–19 years with blood lead levels (BLLs) below 5 µg/dL (n = 11,978). BLLs were categorized into either two groups based on the median BLL (i.e., <0.70 µg/dL and ≥0.70 µg/dL) or four quartiles (i.e., quartile 1: <0.46 µg/dL; quartile 2: 0.46–<0.70 µg/dL; quartile 3: 0.70–<1.00 µg/dL; and quartile 4: ≥1.00 µg/dL). Multivariable linear regression analysis was conducted to assess the association between BLLs and serum GGT concentrations among U.S. adolescents aged 12–19 years. Results: Adolescents with BLLs ≥ 0.70 µg/dL showed significantly higher serum GGT concentrations compared to those with BLLs < 0.70 µg/dL (geometric means: 13.94 vs. 12.80 U/L; p < 0.001). The multivariable linear regression analysis indicated that, after adjusting for potential confounding factors, natural log-transformed serum GGT concentrations were higher among adolescents in BLL quartile 4 compared to those in BLL quartile 1 (β-coefficient = 0.0607; 95% CI: 0.0306, 0.0908). However, no significant associations were observed between BLLs and serum GGT concentrations among adolescents in BLL quartiles 2 and 3 when compared to quartile 1. Conclusions: In the present study, we observed that higher BLLs were associated with higher serum GGT concentrations in U.S. adolescents aged 12–19 years. Further research is needed to substantiate the positive relationship between BLLs and serum GGT and explore the mechanisms underlying their interaction with oxidative stress in adolescents. Full article

Background/Objectives: Shift-working healthcare professionals are exposed to high psychophysiological demands associated with occupational stress, anxiety, and depressive symptoms. Salivary chromogranin A (sCgA) and secretory immunoglobulin A (sIgA) are non-invasive biomarkers reflecting sympathetic nervous system activation and mucosal immune function, respectively, and are increasingly used to assess biological stress responses. This study examined changes in these biomarkers and their associations with anxiety and depression. Methods: This cross-sectional comparative observational study was conducted among healthcare professionals working 12-h shifts (n = 95) and non-shift-working controls (n = 95) and included a within-shift pre-post assessment, with saliva samples collected before and after the work shift. Salivary biomarkers were determined using ELISA methods. Anxiety and depression were assessed using the State–Trait Anxiety Inventory and the Zung Self-Rating Depression Scale. Data were analyzed with t-tests, correlation, and multiple linear regression. Statistical analyses included between- and within-group comparisons, correlation analyses, and multiple linear regression models to examine independent associations between salivary biomarkers and psychological outcomes. Results: After a 12-h shift, healthcare professionals showed increased sCgA (3.82 ± 0.95 vs. 4.68 ± 1.02 ng/mL; p < 0.001) and decreased sIgA (165.3 ± 32.4 vs. 142.6 ± 29.8 mg/dL; p < 0.001). Psychological scores were higher in healthcare professionals than in controls (p < 0.001). Salivary sCgA correlated positively with anxiety and depression (r = 0.41 to 0.45), while sIgA correlated negatively (r = −0.29 to −0.36). Regression analysis confirmed occupational group (healthcare professionals vs. controls) as the strongest predictor, with independent contributions of sCgA and sIgA to psychological scores. Conclusions: A 12-h work shift in healthcare professionals leads to increased salivary chromogranin A, indicating sympathetic activation, and decreased secretory IgA, reflecting reduced mucosal immune activity. The combined assessment of sCgA and sIgA provides a sensitive and non-invasive approach for monitoring occupational stress and identifying early risks of anxiety and depressive symptoms among shift-working healthcare professionals. Full article

Suckler beef cows and their calves are commonly separated when calves are between four and ten months old. This is earlier than would happen naturally and causes stress in dams and calves and reduces feed intake and immunocompetence, and thus introduces calf performance and health problems. To address these concerns, weaning by separation was gradually phased out on a single extensive suckler beef farm comprising nine separate breeding herds based on chalk downland in southern England. Over seven consecutive years, the farm’s breeding herds were converted to natural weaning, one to two herds per year. This meant yearling calves stayed with their dams until weaned off naturally and beyond the subsequent calving season. To examine the effects of yearlings being left with their dams, retrospective data were collected on the subsequent calves’ survival to one year old (‘raising success’). The dams had their previous calf either still present as a yearling (YP) when the new calf arrived or had had their previous calf removed at eight months old, so it was absent (YA). Data were retrospectively analysed on 1822 calves born to 663 dams in total over the seven years. Raising success overall was 96% for YP calves and 95% for YA. Chi-squared analysis of only one calf per cow (N = 663; YP = 382, YA = 281) confirmed that raising success was not negatively associated with yearling presence. A separate analysis compared farm data on serum total protein levels of 81 YP and 12 YA 1–10-day-old calves as measures of colostrum antibody uptake. Mann–Whitney U testing showed an insignificant trend towards higher antibody uptake in YA calves (p < 0.1). However, over 86% of calves in both groups had ‘excellent’ total protein values according to a standard classification used for dairy calves (>6.2 g/dL). The findings show for the first time and under conditions studied here that beef calves can be left with their dams without a negative effect on the survival of the subsequent calf. Concerns of sibling rivalry disturbing the bonding process and leading to competition for colostrum and milk were not confirmed. In conclusion, allowing cows to wean their calves naturally could potentially be a viable management option for similar beef suckler herds, including those used in habitat/soil restoration projects. Full article

The durability of concrete in immersed tunnels is critically influenced by the coupled effects of stress, seepage, and chemical erosion, particularly in inland water environments. However, the spatio-temporal evolution of mechanical property degradation under such multi-field coupling remains insufficiently quantified. Unlike previous studies focused on “load-ion” or “hydraulic pressure-ion” dual coupling, this work introduces a complete stress–seepage–chemical tri-coupling that incorporates the critical seepage effect, representing a fundamental expansion of the experimental scope to better simulate real-world conditions. This study investigates the degradation mechanisms of concrete in the Shunde Lungui Road inland immersed tunnel subjected to such coupled erosion. A novel aspect of our approach is the application of the micro-indentation technique to quantitatively characterize the spatio-temporal evolution of the local elastic modulus at an unprecedented spatial resolution (0.5 mm intervals), a dimension of analysis not achievable by conventional macro-scale testing. Key findings reveal that the mechanical properties of concrete exhibit an initial enhancement followed by deterioration. This behavior is attributed to the filling of pores by reaction products (gypsum, ettringite, and Friedel’s salt) in the short term, which subsequently induces microcracking as the volume of products exceeds the pore capacity. Furthermore, increasing hydro-mechanical loading significantly accelerates the erosion process. When the load increases from 1.596 kN to 3.718 kN, the influence range of elastic modulus variation expands by 9.2% (from 5.186 mm to 5.661 mm). To quantitatively describe this acceleration effect, a novel load-acceleration erosion coefficient is proposed. The erosion rate increases from 0.0688 mm/d to 0.0778 mm/d, yielding acceleration coefficients between 1.100 and 1.165, quantifying a 10–16.5% acceleration effect beyond what is typically captured in dual-coupling models. These quantitative results provide critical parameters for employing laboratory accelerated tests to evaluate the ionic erosion durability of concrete structures under various loading conditions, thereby contributing to more accurate service life predictions for engineering structures. Full article

Background: Sedentary behavior is prevalent among female college students and may negatively affect motor competence—a key component of physical literacy and lifelong health. However, limited research has compared motor proficiency across distinct physical activity patterns in this population. This study aimed to examine differences in motor proficiency between sedentary and regularly active female college students. Methods: A cross-sectional study was conducted with 292 female undergraduates (aged 18–21 years). Participants were retrospectively classified into a sedentary behavior group (SBG; n = 124) and a regular exercise group (REG; n = 168) according to the International Physical Activity Questionnaire–Short Form (IPAQ-SF). Motor proficiency was evaluated using the Bruininks–Oseretsky Test of Motor Proficiency, Second Edition (BOT-2). Group differences were analyzed using multivariate analysis of variance (MANOVA) and independent-samples t-tests. Results: The REG demonstrated significantly higher scores in manual coordination, body coordination, and strength and agility (all p < 0.01), whereas no significant difference was observed in fine motor control. The REG also exhibited a higher total BOT-2 score (p < 0.01; Cohen’s d = 0.56). Conclusions: Regular physical activity was associated with higher motor proficiency among female college students. As this study used a cross-sectional design, causal relationships cannot be inferred. Nonetheless, these findings highlight the potential importance of promoting active lifestyles in higher education to enhance motor competence and contribute to long-term public health. Full article

Aging and institutionalization, associated with functional and psychological decline, justify studying how physical performance is linked to mental health in older adults. Objectives: To analyze the relationship between physical performance and anxiety, depression, sleep quality, and perceived stress in institutionalized older adults. Methods: Multicenter, observational, cross-sectional study in eight nursing homes (N = 105; ≥65 years, M = 80.78 SD ± 7.91). Instruments: SPPB, HADS, PSQI, PSS-10. Descriptives and exploratory bivariate tests. Primary analysis: single multivariable linear regression with SPPB as outcome and HADS-A, HADS-D, PSQI, PSS-10 entered simultaneously, adjusted for age and sex. Robustness: GLM with robust SEs, influence sensitivity excluding Cook’s D > 4/n or leverage > 2 p/n, and a proportional-odds model for SPPB. All statistical tests were two-sided, with α set at 0.05. Results: Mean SPPB was 6.94 ± 3.17; 77.1% of participants showed poor physical performance. Bivariate: All mental health constructs showed significant associations with physical performance. Multivariable model: adjusted R² = 0.198; F (6,98) = 5.28, p < 0.001. Depression B = −0.230 (95% CI −0.398 to −0.061), p = 0.008; sleep quality (higher = worse) B = −0.187 (95% CI −0.351 to −0.024), p = 0.025; age B = −0.087 (95% CI −0.158 to −0.017), p = 0.016. Anxiety showed a positive adjusted association B = +0.224 (95% CI 0.038 to 0.410), p = 0.019 (consistent with suppression); perceived stress B = −0.062, p = 0.275; sex B = −0.144, p = 0.812. Robust SEs left inferences unchanged. Influence sensitivity (n = 97) preserved directions with the PSQI association attenuating to non-significance. Ordinal results were directionally consistent. Conclusions: After adjusting for age and sex, depression and sleep quality independently relate to physical function, while age is inversely associated; anxiety and perceived stress show no independent effects. Full article

Treating wastewater with a low carbon-to-nitrogen (C/N) ratio remains a major challenge for conventional biological processes because insufficient organic carbon limits heterotrophic denitrification. To address this issue, microalgae-based photobioreactors offer a sustainable alternative that couples nutrient removal with biomass valorization. This study systematically evaluated the effects of four key operational parameters—initial inoculum density, aeration rate, light intensity, and photoperiod—on nutrient removal, biomass productivity, and metabolite accumulation of Auxenochlorella pyrenoidosa (A. pyrenoidosa) treating synthetic low C/N wastewater. Optimal operating conditions were identified as an initial OD₆₈₀ of 0.1, aeration rate of 2 L air min⁻¹, light intensity of 112 μmol m⁻² s⁻¹, and a 16L:8D photoperiod. Under these conditions, the photobioreactor achieved 86.35% total nitrogen and 98.43% total phosphorus removal within 11 days while producing biomass rich in proteins, polysaccharides, and lipids. Metagenomic analysis revealed a metabolic transition from denitrification-driven pathways during early operation to assimilation-dominated nitrogen metabolism under optimized conditions, emphasizing the synergistic interactions within algal–bacterial consortia. These findings demonstrate that optimized A. pyrenoidosa-based photobioreactors can effectively recover nutrients and produce valuable biomass, offering a viable and sustainable solution for the treatment of low C/N wastewater. Full article

A combination of stomach contents analysis (SCA) and nitrogen (δ¹⁵N) and carbon (δ¹³C) stable isotope analysis (SIA) was used to assess the trophic structure of nine fish species (two belonging to the family Mullidae, Mullus barbatus and Mullus surmuletus, and seven belonging to the family Sparidae, Diplodus sargus, Diplodus vulgaris, Pagellus acarne, Pagellus erythrinus, Pagrus auriga, Pagrus pagrus, and Sparus aurata) with high commercial value in the Bay of Cádiz, Southern Spain. A total of 91 different food items were identified in the stomachs, mainly belonging to four animal phyla (Arthropoda, Mollusca, Annelida, and Echinodermata). Crustaceans (primarily decapods and amphipods) were the most common prey consumed by the species of Mullus, Pagrus, and Pagellus, whereas macroalgae, polychaetes, and molluscs were dominant in D. sargus, D. vulgaris, and S. aurata stomachs, respectively. Diet composition and isotopic signature differed among fish species, indicating food partitioning among coexisting species. Some discrepancies appeared when comparing fish trophic level using SCA versus SIA, since SCA provides information on recently consumed items, while SIA generates data about source utilization over a period of several months. Integration of both approaches offers a more comprehensive understanding of feeding strategies. Dietary studies shed light on the trophic ecology of commercial fish species, being the baseline for future ecological modelling and long-term management of marine resources. Full article

Background/aim: Vitamin D (VitD) has been implicated in neuroprotection, yet its role in Parkinson’s disease (PD) remains unclear. This systematic review and meta-analysis aimed to evaluate the association between VitD status, supplementation, and vitamin D receptor (VDR) gene polymorphisms with PD risk and outcomes. Methodology: Following PRISMA guidelines, we searched PubMed, Scopus, and Google Scholar through August 2025 for observational studies, clinical trials, and genetic association studies. Primary outcomes included serum VitD levels in PD versus healthy controls (HCs), prevalence of VitD insufficiency/deficiency, and effects of VitD supplementation on motor symptoms. Secondary outcomes assessed associations between VDR polymorphisms and PD susceptibility. Data were synthesized using random- and fixed-effects models, with heterogeneity and publication bias evaluated. PROSPERO (CRD420251133875). Results: Sixty-three studies (n ≈ 10,700 participants) met inclusion criteria. PD patients exhibited significantly lower VitD levels (SMD = −0.46; 95% CI: −0.51 to −0.41) and higher odds of insufficiency (OR = 1.52) and deficiency (OR = 2.20) compared to HC. Cohort data suggested sufficient VitD may reduce PD risk (HR = 0.83). Supplementation yielded modest, non-significant improvements in motor outcomes. Among 20 genetic studies, FokI (rs2228570) was most consistently associated with PD, while other VDR SNPs showed variable or null associations. Conclusions: VitD deficiency is common in PD and may influence disease risk and motor function. Current evidence indicates limited benefit of supplementation for motor outcomes, and genetic associations remain inconsistent. Full article