Search Results (358)

Bisphenol A (BPA) is a common synthetic chemical compound classified as an endocrine disruptor. It affects multiple physiological systems in the body, including the female reproductive system, particularly granulosa cells (GCs) in the ovaries, where steroidogenesis occurs. This study investigated the impact of various BPA concentrations (environmentally relevant concentrations of 0.001 µM and 0.1 µM and toxicological concentration of 100 µM) and exposure times (24 and 72 h) on cell viability and counts and in vitro production of estradiol and progesterone in human GCs collected from waste follicular fluid of IVF patients. Gene expression analysis of 182 genes associated with steroidogenesis and apoptosis was performed in GCs using PCR arrays, followed by protein expression analysis by Western blot. Our results demonstrate that after longer BPA exposure (72 h), a higher concentration of BPA (100 µM) negatively affects the cellular viability and counts and significantly alters steroid hormone biosynthesis in vitro, leading to reduced concentrations of estradiol and progesterone in the culture medium. We found that all BPA concentrations altered the expression of different steroidogenesis- and apoptosis-related genes in GCs. At 0.001 μM, BPA exposure decreased the expression of TRIM25, UGT2B15, CASP3, and RPS6KA3 genes and increased the expression of NR6A1 and PPID genes. At 0.1 μM, BPA increased the expression of AR, HSD3B1, BID, IKBKG, and PPID genes while reducing the expression of TRIM25 and CASP3 genes. At the highest concentration of 100 μM, BPA upregulated the expression of AR, GPER30, BID, IKBKG, and PPID genes and downregulated the expression of FOXO1 and UGT2B15 genes. These results highlight BPA’s concentration-specific effects on steroidogenesis and apoptosis and show its potential to compromise GC function, with possible negative implications for female fertility and ovarian health, even at environmentally relevant concentrations. Full article

Introduction: Hemangioblastomas (HBs) are benign, highly vascular tumors that can be found intracranially or in the spinal region, representing around 2–15% of primary intramedullary tumors. They can occur sporadically or in association with Von Hipple–Lindau (VHL) disease. Despite recent of advancement of nonsurgical treatments, complete surgical resection remains the gold standard of care for the spinal HBs. Materials and Methods: We conducted an international multicenter retrospective analysis of adult patients surgically treated for spinal HBs in four European referral centers between January 2000 and September 2024, with a minimum post-operative follow-up duration of 6 months. Patients’ sex and age at surgical intervention, clinical presentation, and duration symptoms prior to clinical diagnosis were identified. The pre- and post-operative neurological status at 1 and 6 months and at the last visit was assessed using the modified McCormick score (MCS). The extent of surgical resection was divided into gross total resection (GTR) and subtotal resection (STR). Finally, post-operative complications were inspected as well, namely cerebrospinal fluid leaks, infections, hemorrhages and post-operative spinal stability. Results: A total of 35 patients were included in the cohort, with an age median of 52 years (34.5–60) and a slight male predominance (21/35, i.e., 60%). The median follow-up period was 37.5 months (12–75). More than half were located in the cervical region, making it the most common (54.3%). Syrinxes were observed in 23 cases (72%), and HBs were more commonly intramedullary (80%). GTR was achievable in around 88% of cases. Post-operative complications were observed in nine patients (25.7%). Nearly half of patients were discharged into rehabilitations centers (48.5%). Tumor recurrence was seen in 10.3% only. At the last follow-up, an excellent overall post-operative neurological status (positive ∆ McCormick) was observed in most of patients (88%) and was found to be associated with a relatively younger age group. Tumor location and presence of syrinxes did not show any statistical significance regarding clinical outcome. In patients having benefited from intra-operative monitoring, only D-wave changes showed statistical significance regarding post-operative outcome (p < 0.05). Conclusions: A large majority of patients operated for a spinal HB demonstrated favorable outcome after surgery, with unchanged or improved neurological status. Advanced age could have an impact on the post-operative neurological outcome. Other factors such as tumor size, location, and the presence of syrinx did not seem to significantly impact the neurological outcome. Finally, the surgery of these vascular lesions with no possibility of debulking or piece-meal removal and requiring “en bloc” resection is technically demanding and should be performed by experienced teams in spine and spinal cord surgery only. Full article

AZ31B magnesium alloy (wt.%: Al 2.94; Zn 0.87; Mn 0.57; Si 0.0112; Fe 0.0027; Cu 0.0008; Ni 0.0005; Mg remaining) has appropriate mechanical properties, good biodegradability and biocompatibility and can be used as a good orthopedic implant material. AZ31B magnesium alloy with a superhydrophobic surface exhibits excellent corrosion resistance and antibacterial adhesion performance, but superhydrophobic surfaces also hinder osteoblast adhesion and proliferation on the implants, resulting in unsatisfactory osteogenic properties. Therefore, it is necessary to achieve the wettability transition of the superhydrophobic surface at an early stage of implantation. In this work, superhydrophobic hydroxyapatite (HA)/calcium myristate (CaMS)/myristic acid (MA) composite coatings were prepared on AZ31B magnesium alloy using the hydrothermal and immersion methods. The composite coatings can spontaneously undergo the wettability transition from superhydrophobic to hydrophilic after complete exposure to simulated body fluid (SBF, a solution for modeling the composition and concentration of human plasma ions) for 9 h. The wettability transition mainly originated from the deposition and growth of the newly formed CaMS among the HA nanopillars during immersing, which deconstructed the micro-nano structure of the superhydrophobic coatings and directly exposed the HA to the water molecules, thereby significantly altering the wettability of the coatings. Benefiting from the superhydrophobic surface, the composite coating exhibited excellent antibacterial properties. After the wettability transition, the HA/CaMS/MA composite coating exhibited superior osteoblast adhesion performance. This work provides a strategy to enable a superhydrophobic coating to undergo spontaneous wettability transition in SBF, thereby endowing the coated magnesium alloy with a favorable osteogenic property. Full article

Background: Achieving pharmacokinetic/pharmacodynamic (PK/PD) targets is critical for improving treatment success, particularly in critically ill patients. This study investigates the role of inflammatory biomarkers and their influence on the PK/PD characteristics of polymyxin B (PMB) in patients with extensively drug-resistant Gram-negative (XDR-GN) bacterial nosocomial pneumonia. Methods: Serial blood and/or bronchoalveolar lavage fluid (BALF) samples were collected at specified time points and analyzed for PMB and/or inflammatory biomarkers, including IL-6 and IL-10. Clinical data were also recorded, and their correlations with PK parameters were further analyzed. Results: Among the 27 enrolled patients, 22 (81.5%) achieved treatment success. The pharmacokinetic parameters of PMB included a maximum plasma concentration (C_max) of 8.3 µg/mL, clearance (CL) of 1.55 L/h, volume of distribution (Vd) of 30.44 L, half-life (t_1/2) of 19.56 h, steady-state area under the plasma concentration–time curve from time 0 to 24 h (AUC_ss,0–24h) of 110.08 h·µg/mL, and a plasma protein-binding ratio of 85.53%. The AUC_ss,0–24h metric was identified as a robust predictor of clinical efficacy, with an optimal cutoff value of 77.27 h·µg/mL. Notably, 48.15% of patients achieved the target AUC_ss,0–24h range of 50–100 h·µg/mL, with 76.95% of these patients attaining treatment success. Another 48.15% of patients exceeded this target, and 92.31% of this subgroup achieved treatment success. PMB demonstrated limited pulmonary penetration, with an epithelial lining fluid (ELF)/plasma ratio of 15.69% [16.86, 18.15]. Furthermore, TNF-α and the IL-6/IL-10 ratio were significantly correlated with PMB PK parameters. Conclusions: Our and others’ studies suggest heterogeneity of PMB PK parameters in critically ill patients. The majority of critically ill patients achieved or surpassed the recommended PK/PD targets and attained treatment success through intravenous administration of PMB at a simplified fixed dose. However, PMB did not achieve satisfactory pulmonary concentrations, suggesting that its efficacy may involve alternative mechanisms. The modulation of inflammatory responses may play a pivotal role in the treatment of severe infections, highlighting the potential for biomarker-guided therapeutic strategies. Full article

Background: Metritis, a common postpartum uterine infection in bovines, poses substantial challenges in livestock management, including compromised fertility and economic losses. Poor uterine drug penetration and systemic side effects, necessitating innovative localised delivery systems and limiting current systemic antibiotic treatments. Aim: This study aimed to develop and evaluate the potential effect of the ofloxacin-loaded hydrogel as a localised drug delivery system to treat metritis in bovine. The focus was on achieving sustained drug release, enhanced antibacterial efficacy and reduced inflammation in the endometrium. Materials and Methods: The CS/PVA hydrogel was synthesised using a freeze–thaw method and further optimised for drug encapsulation efficiency (96.7 ± 2.1%), stability and biocompatibility. Physicochemical characterisation included swelling behaviour, mechanical properties and rheological analysis. In vitro drug release profiles in the simulated uterine fluid were assessed over 72 h and antibacterial activity was tested against common uterine pathogens such as Escherichia coli and S. aureus. In vivo studies were conducted on bovines diagnosed with endometritis to evaluate clinical recovery. Results: The SEM image of the ofloxacin-loaded CS/PVA hydrogel resulted in a smooth and porous structure demonstrating larger pore size than the blank. The rheological study suggested higher stability and elastic behaviour. Antibacterial assays on E. coli and S. aureus revealed significant inhibition zones, respectively, indicating potent efficacy. In vivo, evaluated on treated bovine, reduced bacterial loads were exhibited (2.86 × 10^5A CFU/mL → 6.37 × 10^2B CFU/mL), clinical improvement was marked and uterine inflammation was resolved. Conclusions: Ofloxacin-loaded hydrogels represent a promising localised treatment for bovine metritis, offering sustained antibacterial action and improved clinical outcomes. This approach addresses the limitations of systemic antibiotic therapies and provides a practical solution for enhanced veterinary care. Further studies are recommended to validate these findings in more extensive field trials and explore commercialisation potential. Full article

This paper investigates the linear stability of the liquid film of Oldroyd-B fluid on an oscillating plate. The time-dependent Orr–Sommerfeld boundary-value problem is formulated through the assumption of a normal modal solution and the introduction of the stream function, which is further transformed into the Floquet system. A long-wavelength expansion analysis is performed to derive the analytical solution of the Orr–Sommerfeld equation. The results indicate that long-wave instability occurs only within specific bandwidths related to the Ohnesorge number ($Oh$). Fixing the elasticity parameter ($El$) and increasing the relaxation-to-delay time ratio ($\tilde{\lambda }$) from 2 to 4 or fixing ($\tilde{\lambda }$) and increasing ($El$) from 0.001 to 0.01 decreases the number of unstable bandwidths while enhancing the intensity of unstable modes. Increasing the surface-tension-related parameter (${\zeta }^{\ast }$) from 0 to 100 suppresses the wave growth rate, stabilizing the system. Additionally, increasing ($\tilde{\lambda }$) from 2 to 4 reduces the maximum values of the coupling of viscoelastic, gravitational, and surface-tension forces, as well as the maximum value of the Floquet exponent, further stabilizing the system. These findings provide supplements to the theoretical research on the stability of viscoelastic fluids and also offer a scientific basis for engineering applications in multiple fields. Full article

Recent U.S. military conflicts have underscored the knowledge gap regarding the neurological changes associated with blast-induced traumatic brain injury (bTBI). In vitro models of TBIs have the advantage of following the neuronal response to biomechanical perturbations in real-time, which can be exceedingly difficult in animal models. Here, we sought to develop an in vitro approach with controlled blast biomechanics to study the direct effects of the primary shock wave at the neuronal level. A blast injury apparatus mimicking the human skull and cerebrospinal fluid was developed. Primary neuronal cells were cultured inside the apparatus and exposed to a 70 kPa peak blast overpressure using helium gas in a blast tube. Neuronal viability was measured 24 h after blast exposure. The transmission of the pressure wave through the skull is believed to be a factor in injury to the cells of the brain. Three thicknesses in the apparatus wall were studied to represent the range of thicknesses in a human skull. To study the transmission of the shock wave to the neurons, the incident pressure at the apparatus location, as well as internal apparatus pressure, were measured. Analysis of the internal pressure wave revealed that wave oscillation frequency, not amplitude, was a significant factor in cell viability after a bTBI. This finding is related to the viscoelastic properties of the brain and suggests that the transmission of the shock wave through the skull is an important variable in blast injury. Full article

The total installed geothermal power plant capacity at year-end 2023 was 16,335 MW, while the forecast for the installed capacity in 2025 is 19,331 MW. In Croatia, several medium-temperature geothermal resources (geothermal water) with temperatures from 90 to 200 °C exist, by means of which it is possible to produce electricity in binary plants, with the Organic Rankine Cycle (ORC) or with the Kalina cycle. In earlier studies, the authors presented the results of an energy-exergy analysis of geothermal sources at Velika Ciglena (170 °C), Lunjkovec-Kutnjak (140 °C), Babina Greda (125 °C), and Rečica (120 °C), aiming to determine which binary plant is more suitable for the environmental conditions in Croatia. The calculations indicate that the plant with ORC is thermodynamically superior to the one with the Kalina cycle for all geothermal sources. Taking into account the typical challenges faced by new technologies during their initial implementation, the authors recommend using the ORC plant for all medium-temperature geothermal sources. Literature on ORC applications mainly addresses working fluid selection, unit and plant optimization, and modifications to enhance thermodynamic efficiency or net power output. While many studies on working fluid selection exist, each geothermal source is unique due to its specific temperature and local cooling fluid (water or air). As a result, this paper presents the findings of an analysis on the influence of working fluids on the thermodynamic performance of an ORC system, focusing on the Lunjkovec-Kutnjak Geothermal Power Plant with a geothermal water temperature of 140 °C. As the working fluid, the next are analyzed: isopentane (C₅H₁₂), isobutene (C₄H₁₀), isohexane (C₆H₁₄), R114 (C₂Cl₂F₄), R141B (C₂H₃Cl₂F), and R142B (C₂H₃Cl₂F₂). In respect to cycle efficiency and net power, all working fluids are equally favorable, but R601a (isopentane) with low ALT, ODP, and GWP, favorable upper and lower pressure, is the most suitable fluid for ORC with a medium-temperature geothermal source. Full article

The hydrogen ions in superionic ice can move freely, playing the role of electrons in metals. Its electromagnetic behavior is the key to explaining the anomalous magnetic fields of Uranus and Neptune. Based on an ab initio evolutionary algorithm, we searched for the stable H₄O crystal structure under pressures of 500–5000 GPa and discovered a new layered-chain Pmn2₁-H₄O structure with H₃ ion clusters. Interestingly, H₃ ion clusters rotate above 900 K (with an instantaneous speed of 3000 m/s at 900 K), generating an instantaneous magnetic moment (~10⁻²⁶ A·m² ≈ 0.001 ${\mu }_{\mathrm{B}}$). Moreover, H ions diffuse in a direction perpendicular to the H-O atomic layer at 960–1000 K. This is because the hydrogen–oxygen covalent bonds within the hydrogen–oxygen plane hinder the diffusion behavior of H₃ ion clusters within the plane, resulting in the diffusion of H₃ ion clusters between the hydrogen–oxygen planes and the formation of a one-dimensional conductive superionic state. One-dimensional diffusion of ions may generate magnetic fields. We refer to these two types of magnetic moments as “thermally induced ion magnetic moments”. When the temperature exceeds 1000 K, H ions diffuse in three directions. When the temperature exceeds 6900 K, oxygen atoms diffuse and the system becomes fluid. These findings provide important references for people to re-recognize the physical and chemical properties of hydrogen and oxygen under high pressure, as well as the sources of abnormal magnetic fields in Uranus and Neptune. Full article

Background: Amylase activity is a critical biomarker for assessing the freshness of honey. Historically, bees have been considered the sole source of honey amylase. However, recent studies suggest that Bacillus subtilis may also contribute to amylase production in the honey sac of Apis mellifera. Methods: In this study, amylase levels were measured in samples of nectar, honey sac fluid, and honey. The identification of B. subtilis in nectar, honey sac, and honey was evaluated. An in vitro bacterial culture system and a feeding experiment were developed to simulate honey sac conditions. Results: Our results showed that B. subtilis was detected in all sample groups, with the highest concentration in honey sac samples. Amylase levels in honey sac and honey samples were significantly higher than those in nectar. In the simulation experiment, amylase activity was only observed in cultures containing both B. subtilis and sucrose/nectar; no activity was detected in cultures containing only H₂O or no B. subtilis. In the feeding experiment, bees fed sucrose or nectar showed higher amylase activity in their honey sacs than those fed water. Conclusions: Our data show that B. subtilis can produce amylase and offer potential for more standardized quality assessment of honey. Full article

Background: Exposure to sulfur mustard (SM; 2,2′-dichlorodiethyl sulfide) causes toxicity in the human body, particularly the lungs. The molecular mechanisms of SM-induced lung damage are elusive, and no effective treatments exist. This study explores the anti-inflammatory potential of cannabinoid receptor 2 (CB2R) activation in mitigating acute lung injury (ALI) and inflammation induced by 2-chloroethyl ethyl sulfide (CEES), a structural analog of SM. Methods: C57BL/6J mice were exposed to CEES via intratracheal administration to model ALI. CB2R activation was achieved through the intraperitoneal administration of HU308, a selective synthetic agonist. ALI and inflammation were evaluated at 48 h post-exposure to CEES. Bronchoalveolar lavage fluid (BALF) was collected to measure total cells, protein, and cytokines. Lung injury, inflammatory signaling in alveolar macrophages (AMs), and matrix metalloproteinase-9 (MMP-9) activity were assessed via histological analysis, immunoblotting, and gelatin zymography, respectively. Results: CEES exposure led to an increase in immune cell infiltration, pro-inflammatory cytokines (IL-6 and TNF-α), and pro-MMP9 levels in the BALF, which were significantly decreased by HU308 treatment. The activation of CB2R attenuated CEES-induced NF-κB activation and reduced pro-inflammatory M1 markers (iNOS, and Cox-2) but did not alter the increase in the M2 marker arginase-1. CB2R activation mitigated CEES-induced oxidative stress, as evidenced by lower levels of heme oxygenase-1 (HO-1) and reactive oxygen species (ROS) in mouse AMs. Additionally, 4-hydroxynonenal (4-HNE) levels were reduced in the lungs of HU308-treated mice but were elevated after CEES exposure. Conclusions: These findings suggest that CB2R activation alleviates CEES-induced ALI and inflammation in mice, supporting its potential as a therapeutic approach for vesicant-induced pulmonary injury. Full article

Determining hemicellulose (HM) degradation is crucial for evaluating the nutritional value of ruminant diets. Our previous study showed that oxalic acid (OA) regulates rumen fermentation. Building on this research, the present study examined the effects of OA supplementation in different hemicellulose diets on sheep rumen fermentation, microbial diversity, and metabolite production in vitro. Diets with low and high HM levels (10.3% and 17%, respectively) and supplemented with seven concentrations of OA (0, 2.5, 5, 10, 20, 40, 80 mg/kg DM) were evaluated. Tests were conducted under both low (HM10.3%) and high (HM17%) hemicellulose conditions; however, the addition of 10 mg/kg DM oxalic acid could have better effects under low hemicellulose (HM10.3%), with higher concentrations of acetic, propionic, and butyric acids, as well as total acids. A 2 × 2 factorial design was used to collect rumen fluid after 12 h of fermentation to analyze microbial populations and metabolites. OA supplementation at 10 mg/kg DM significantly increased the relative abundances of several bacterial genera, including Prevotella, Butyrivibrio, Ruminococcus, Sharpea, RFN20, Bulleidia, Olsenella, and Bifidobacterium (p < 0.05). A positive correlation was observed between Butyrivibrio and Sharpea and the production of isobutyric and isovaleric acids (p < 0.01), indicating that these bacteria play a role in volatile fatty acid (VFA) production. Furthermore, rumen metabolites involved in mineral absorption and lipid metabolism, including α-tocopherol, L-glutamic acid, and ginkgolide B, were upregulated. In summary, supplementation with oxalic acid in HM diets alters rumen fermentation, enhances nutrient digestibility, promotes microbial diversity, and influences metabolic pathways. Thus, OA supplementation should be tailored to specific dietary conditions for optimal effects. Full article

Arnica montana (AM), which belongs to the daisy family Asteraceae, has a longstanding traditional use in Europe and North America for pain and inflammation treatment. This study investigates the inhibitory effects of ‘Arnica montana extract hydrogel patch (AHP)’ on Carrageenan-induced paw edema and hot plate-induced pain models. AHP exhibited transdermal permeability without the occurrence of issues like crystal precipitation. This study employed two animal model assessments using AHP, in comparison with Arnicare Gel (AG), to evaluate anti-inflammatory and pain relief effects. AHP treatment for 2 days showed a decrease in paw edema thickness in mice as compared to vehicle or AG groups; Carrageenan-induced swelling increased maximally at 1 h with the AHP group demonstrating a higher reduction. Thus, the AHP group exhibited a lower ratio of right/left paw thickness and a superior reduction in swelling, supportive of its ability to diminish edema. A histological analysis showed that AHP treatment reduced inflammatory cell infiltration. Consistently, the mRNA levels of inflammatory markers (tnfa, il1b, and il6) were decreased to a greater extent than the AG group. Particularly, tnfa inhibition was better in the AHP group, and the levels of il1b and il6 transcripts showed ~80% and 40% lower. Likewise, AHP reduced pain scores in a hot plate-induced rat model, although AG failed to do so. Together, these results demonstrate that AHP has long-lasting inhibitory effects on fluid effusion and edema formation, the production of inflammatory mediators, and pain-sensation, supporting its anti-inflammatory and pain-relieving pharmacological effects. Full article

The transformation of hypoglycin A (HGA), hypoglycin B (HGB), and methylene cyclopropyl glycine (MCPrG) in ruminal fluid batch cultures was investigated, and the effect of these toxins on the batch culture microorganisms using microbial metabolites was measured. An experiment was conducted using ovine ruminal fluid batch cultures and the ANKOM RF Gas Production System over four runs, each with an incubation period of 48 h. The fermenters contained 200 mg of (i) a substrate mixture (80% cellulose, 20% starch; CSM), (ii) CSM and 1.5 mL of a solution of pure toxins (a mixture of 500 ng/mL HGA and MCPrG each; PCM), or (iii) CSM and 100 mg sycamore maple seeds (SMS). Each fermenter contained 30 mL of inoculum (ruminal fluid and buffer, 1:2 v/v). For control, autoclaved ruminal fluid was incubated with CSM, PCM, and SMS, respectively. Samples were taken from the liquid phase of the fermenters and analyzed using liquid chromatography–tandem mass spectrometry (LC/MS-MS) for sycamore maple toxins and metabolites. Microbial activity was assessed using gas production, short chain fatty acids, and NH₃ concentration. Additionally, pH and redox potentials were measured. In PCM, HGA and MCPrG concentrations rapidly decreased (p < 0.05), and were not measurable anymore after a 24 h incubation period. In SMS, the initial concentrations were 4.7 ± 1.4 µg/mL HGA, 19.9 ± 5.41 µg/mL HGB, and 1.2 ± 0.33 µg/mL MCPrG. In SMS, HGA increased in 24 h, coincidently to a decrease in HGB concentration (p < 0.05). We modeled a rapid conversion of HGB to HGA, accompanied by progressive HGA transformation. The concentration of MCPrG was constant until 4 h and decreased afterwards (p < 0.05). In SMS incubations, HGA and MCPrG concentrations of 5.6 ± 1.5 and 0.32 ± 0.090 µg/mL remained after 48 h, respectively. The HGB to HGA conversion and transformation of HGA and MCPrG also occurred in autoclaved ruminal fluid. Gas production and microbial metabolite concentrations were higher in SMS compared to CSM and PCM (p < 0.05), as the seeds were used as an additional substrate by the batch culture microorganisms. Full article

The northeastern Hunan district in the Jiangnan Orogen (South China) holds significant gold resources, whose genesis remains perplexing, especially in terms of the gold source and mineralization process. Yanzhupo (2.50 t @ 2.52 g/t) is a newly discovered gold deposit in the northeastern Hunan district and is characterized by multiple generations of pyrite. Its alteration/mineralization can be divided into three stages: (I) quartz-ankerite-pyrite; (II) quartz-ankerite-chlorite-pyrite-gold; (III) quartz-ankerite-calcite-pyrite. Petrographic observations and back-scattered electron (BSE) imaging revealed six generations of pyrite: Cu-Au rich bright rims (Py1a) and porous cores (Py1b) in Stage I, Py2a with homogenous textures, Py2b with oscillatory zoning and Py2c with homogenous textures in Stage II and Py3 with homogenous textures in Stage III. Galena Pb isotopes, similar to the Wangu deposit, and pyrite chemical compositions show that the ore-forming materials of Yanzhupo came from deep magma, and some metal elements may be extracted from deep basement by fluid-mineral interactions during the upward migration of hydrothermal-magmatic fluid. The positive correlation between Cu and Au in pyrite reflects the oxidized ore-forming fluids. The enrichment of Cu and Au in Py1a reflects the precipitation of pyrite under high temperature fluid, forming the primary enrichment of Au. Porous Py1b is characterized by lower trace elements than Py1a, sharp reaction front and rich chalcopyrite and galena inclusions, indicating Py1b formed via coupled dissolution-reprecipitation (CDR) reactions of Py1a. The CDR reactions promoted by the oxidizing fluid itself re-release Au into the fluid. From Py2a to Py2c, the contents of As, Sb and Pb first increased and then decreased, which may reflect the increase of fluid pH caused by sulfidation of the wall rocks and the impoverishment of ore-forming fluids caused by the precipitation of a large number of elements. The sulfidation of the wall rocks in Stage II destroyed the stability of the Au(HS)₂⁻ and Au (HS)S₃⁻ complexes and led to the deposition of native gold. The barren ore-forming fluids precipitated homogenous Py3 in a stable environment. Therefore, we think that the Yanzhupo gold deposit may have been associated with magmatic-hydrothermal activity, and the mineralization mechanism may be CDR reactions and sulfidation of the wall rocks. Full article