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Potassium channels play essential roles in the regulation of male fertility. However, potassium channels mediating K+ currents in human sperm (IKSper ) remain controversial. Besides SLO3, the SLO1 potassium channel is a potential candidate for human sperm KSper. This study intends to elucidate the function of SLO1 potassium channel during human sperm capacitation. Human sperm were treated with iberiotoxin (IbTX, a SLO1 specific inhibitor) and clofilium (SLO3 inhibitor) separately or simultaneously during in vitro capacitation. A computer-assisted sperm analyzer was used to assess sperm motility. The sperm acrosome reaction (AR) was analyzed using fluorescein isothiocyanate-conjugated Pisum sativum agglutinin staining. Sperm protein tyrosine phosphorylation was studied using western blotting. Intracellular Ca2+ , K+ , Cl- , and pH were analyzed using ion fluorescence probes. Independent inhibition with IbTX or clofilium decreased the sperm hyperactivation, AR, and protein tyrosine phosphorylation, and was accompanied by an increase in [K+ ]i , [Cl- ]i , and pHi , but a decrease in [Ca2+ ]i . Simultaneously inhibition with IbTX and clofilium lower sperm hyperactivation and AR more than independent inhibition. The increase in [K+ ]i , [Cl- ]i , and pHi , and the decrease in [Ca2+ ]i were more pronounced. This study suggested that the SLO1 potassium channel may have synergic roles with SLO3 during human sperm capacitation.
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Reação Acrossômica , Capacitação Espermática , Humanos , Masculino , Capacitação Espermática/fisiologia , Reação Acrossômica/fisiologia , Sêmen/metabolismo , Motilidade dos Espermatozoides , Espermatozoides/metabolismo , Canais de Potássio/metabolismo , HomeostaseRESUMO
The adsorption ability of hydrogen, hydroxide, and oxygenic intermediates plays a crucial role in electrochemical water splitting. Electron-deficient metal-active sites can prompt electrocatalytic activity by improving the adsorption ability of intermediates. However, it remains a significant challenge to synthesize highly abundant and stable electron-deficient metal-active site electrocatalysts. Herein, we present a general approach to synthesizing a hollow ternary metal fluoride (FeCoNiF2) nanoflake array as an efficient and robust bifunctional electrocatalyst for the hydrogen evolution reaction (HER) and urea oxidation reaction (UOR). We find that the F anion withdraws electrons from the metal centers, inducing an electron-deficient metal center catalyst. The rationally designed hollow nanoflake array exhibits the overpotential of 30 mV for HER and 130 mV for UOR at a current density of 10 mA cm-2 and superior stability without decay events over 150 h at a large current density of up to 100 mA cm-2. Remarkably, the assembled urea electrolyzer using a bifunctional hollow FeCoNiF2 nanoflake array catalyst requires cell voltages of only 1.352 and 1.703 V to afford current densities of 10 and 100 mA cm-2, respectively, which are 116 mV less compared with that required for overall water splitting.
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In October 2020, an avian paramyxovirus serotype 14 (APMV-14)-designated chicken/Fujian/2160/2020 (FJ2160) was isolated from tracheal and cloacal swab sample of chicken collected from live bird market in Fujian province in China during the active surveillance program. The complete genome of FJ2160 comprised 15,444 nucleotides (nt) complying with the paramyxovirus "rule of six" and encoded six non-overlapping structural proteins in the order of 3'-NP-P-M-F-HN-L-'5. The complete genome sequence analysis showed that FJ2160 had the highest identity (90.0%) with the APMV-14 isolated from Japan, while the nucleotide sequence identities of FJ2160 and other APMVs ranged from 42.4 to 51.1%. The F protein cleavage site was TREGR↓L, which resembled a lentogenic strain of APMV-1. Phylogenetic analysis revealed that the FJ2160 closest relative was APMV-14. The intracerebral pathogenicity index (ICPI) tests indicated that the virus was lentogenic. This is the first report of APMV-14 in China. These results provide evidence that APMV-14 could infect chickens and reveal the genetic characteristics and biological properties of the virus, which can help to better understand this new emerging APMV-14.
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Avulavirus , Galinhas , Animais , Sorogrupo , Genoma Viral/genética , Avulavirus/genética , Filogenia , ChinaRESUMO
BACKGROUND: The H5 subtype avian influenza virus (AIV) has caused huge economic losses to the poultry industry and is a threat to human health. A rapid and simple test is needed to confirm infection in suspected cases during disease outbreaks. METHODS: In this study, we developed a reverse transcription recombinase-aided amplification (RT-RAA) assay for the detection of H5 subtype AIV. Assays were performed at a single temperature (39 °C), and the results were obtained within 20 min. RESULTS: The assay showed no cross-detection with Newcastle disease virus or infectious bronchitis virus. The analytical sensitivity was 103 RNA copies/µL at a 95% confidence interval according to probit regression analysis, with 100% specificity. Compared with published reverse transcription quantitative real-time polymerase chain reaction assays, the κ value of the RT-RAA assay in 420 avian clinical samples was 0.983 (p < 0.001). The sensitivity for avian clinical sample detection was 97.26% (95% CI, 89.56-99.52%), and the specificity was 100% (95% CI, 98.64-100%). CONCLUSIONS: These results indicated that our RT-RAA assay may be a valuable tool for detecting H5 subtype AIV.
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Vírus da Influenza A , Influenza Aviária , Animais , Aves , Humanos , Vírus da Influenza A/genética , Vírus da Influenza A/metabolismo , Influenza Aviária/diagnóstico , Recombinases/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Transcrição Reversa , Sensibilidade e EspecificidadeRESUMO
Non-receptor tyrosine kinases (NRTKs) are implicated in various biological processes including cell proliferation, differentiation, survival, and apoptosis, as well as cell adhesion and movement. NRTKs are expressed in all mammals and in different cell types, with extraordinarily high expression in the testis. Their association with the plasma membrane and dynamic subcellular localization are crucial parameters in their activation and function. Many NRTKs are found in endosomal protein trafficking pathways, which suggests a novel mechanism to regulate the timely junction restructuring in the mammalian testis to facilitate spermiation and germ cell transport across the seminiferous epithelium.
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Epitélio Seminífero , Espermatogênese , Animais , Adesão Celular , Masculino , Células de Sertoli , Testículo , TirosinaRESUMO
A binder-free attachment method for TiO2 on a substrate has been sought to retain high active photocatalysis. Here, we report a binder-free covalent coating of phase-selectively disordered TiO2 on a hydroxylated silicon oxide (SiO2) substrate through rapid microwave treatment. We found that Ti-O-Si and Ti-O-Ti bonds were formed through a condensation reaction between the hydroxyl groups of the disordered TiO2 and Si substrate, and the disordered TiO2 nanoparticles themselves, respectively. This covalent coating approach can steadily hold the active photocatalytic materials on the substrates and provide long-term stability. The binder-free disordered TiO2 coating film can have a thickness (above 38 µm) with high surface integrity with a strong adhesion force (15.2 N) against the SiO2 substrate, which leads to the production of a rigid and stable TiO2 film. This microwave treated TiO2 coating film showed significant volatile organic compounds degradation abilities under visible light irradiation. The microwave coated selectively reduced TiO2 realized around 75% acetaldehyde degradation within 12 h and almost 90% toluene degradation after 9 h, also retains stable photodegradation performance during the cycling test. Thus, the microwave coating approach allowed the preparation of the binder-free TiO2 film as a scalable and cost-effective method to manufacture the TiO2 film that shows an excellent coating quality and strengthens the application as a photocatalyst under severe conditions.
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The depletion of fossil fuels has accelerated the search for clean, sustainable, scalable, and environmentally friendly alternative energy sources. Hydrogen is a potential energy carrier because of its advantageous properties, and the electrolysis of water is considered as an efficient method for its industrial production. However, the high-energy conversion efficiency of electrochemical water splitting requires cost-effective and highly active electrocatalysts. Therefore, researchers have aimed to develop high-performance electrode materials based on non-precious and abundant transition metals for conversion devices. Moreover, to further reduce the cost and complexity in real-world applications, bifunctional catalysts that can be simultaneously active on both the anodic (i.e., oxygen evolution reaction, OER) and cathodic (i.e., hydrogen evolution reaction, HER) sides are economically and technically desirable. This Minireview focuses on the recent progress in transition-metal-based materials as bifunctional electrocatalysts, including several promising strategies to promote electrocatalytic activities for overall water splitting in alkaline media, such as chemical doping, defect (vacancy) engineering, phase engineering, facet engineering, and structure engineering. Finally, the potential for further developments in rational electrode materials design is also discussed.
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OBJECTIVE: To analyze the changes of hemorheology, haemodynamics and immune function of patients during propofol intravenous anesthesia in the radical resection of colorectal carcinoma and its significance. METHODS: The study included 112 patients who underwent radical resection of colorectal carcinoma in our hospital between August 2016 and December 2017, and they were divided into an observation group (N=56) and a control group (N=56) using random number table. Patients in the observation group were given propofol intravenous anesthesia, while patients in the control group received inhalation anesthesia of sevoflurane. Hemorheological and haemodynamical indexes were compared and analyzed before anesthesia (T0), 90 min after induction (T1), 150 min after induction (T2) and 30 min after entering post-anesthesia care unit (T3), and the changes of immune function before and after surgery was also observed. RESULTS: The whole blood viscosity under high, medium and low shear rates of the observation group declined significantly compared to that of the control group at T1, T2 and T3 (P<0.05). The heart rate (HR) and systolic pressure (SPB) of the observation group significantly decreased at T2 compared to those at T1 (P<0.05), but recovered to the level observed at T0 at T3. The diastolic blood pressure (DBP) of the two groups at T1, T2 and T3 was not significantly different with that at T0 (P>0.05). The levels of CD45RA+ and CD45RO+ of both groups had a significant decrease at the end of the surgery compared to before anesthesia (P<0.05); the levels of the observation group recovered at the postoperative 72nd h, and the differences with the levels before anesthesia had no statistical significance (P>0.05); the level of CD45RA+ of the control group also recovered at the postoperative 72nd h, but the difference with the level before anesthesia had no statistical significance (P>0.05); the level of CD45RO+ of the control group had a significant decrease, and the difference with the level before anesthesia was statistically significant (P<0.05). The level of CD45RA+/CD45RO+ of the observation group at the end of surgery and the postoperative 72nd h was not significantly different with those before anesthesia (P>0.05). The level of CD45RA+/CD45RO+ of the control group at the postoperative 72nd h showed a significant increase compared to before anesthesia (P<0.05). CONCLUSION: Propofol intravenous anesthesia has a significant improvement effect on hemorheology before radical resection of colorectal carcinoma and has a small influence on haemodynamics. Moreover it is beneficial to the recovery of immune function. The therapy is worth promotion.
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PURPOSE: To investigate the effects of silibinin, a natural compound, on the proliferation and apoptosis of BGC-823 gastric cancer cell line and to figure out the relevant pathways. METHODS: BGC-823 gastric cancer cells were treated with silibinin at various concentrations (0,25,50,100,150 and 200µM). Zero µM was the control group and the other concentrations were defined as the experimental groups. The effects of silibinin on the proliferation of BGC-823 gastric cancer cells were explored through methylthiazolyldiphenyltetrazolium bromide (MTT). Silibinin's toxic effects were detected through determination of the concentration of lactic dehydrogenase (LDH). Flow cytometry was performed to explore the effects of silibinin on apoptosis of these cells. Western blotting was conducted to study the relevant pathways acting on the BGC-823 cells. RESULTS: MTT assay showed that with the increase in silibinin concentration and extension of exposure time, the inhibitory effect silibinin on cell proliferation was enhanced in an obvious time-dosage pattern. The results of LDH detection showed that the toxicity of silibinin to cells was enhanced in an obvious time-dosage pattern with the increase in drug concentration and extension of exposure time. Flow cytometry revealed that with the increase in drug concentration, gradual increase in the proportion of early and late of apoptotic cells took place, and the comparison between the experimental and the control group showed that the difference had statistical significance. Western blotting indicated that silibinin could upregulate the expression of mitochondrial apoptosis-associated proteins, and the difference in comparison with the control group had statistical significance. CONCLUSION: Silibinin can inhibit the proliferation of BGC- 823 gastric cancer cells, and such an inhibitory effect is time- and concentration-dependent. Additionally, silibinin can promote the apoptosis of BGC-823 gastric cancer cells, which may be realized through mitochondrial apoptosis.
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Antineoplásicos Fitogênicos/uso terapêutico , Caspase 3/metabolismo , Silibina/uso terapêutico , Neoplasias Gástricas/tratamento farmacológico , Antineoplásicos Fitogênicos/farmacologia , Apoptose , Linhagem Celular Tumoral , Feminino , Humanos , Masculino , Silibina/farmacologia , Neoplasias Gástricas/patologiaRESUMO
OBJECTIVE: We explored which internal genes of influenza virus that affect the titer of recombinant viruses and contribute to the high yield of Influenza A seed virus in ovo. METHODS: Six internal genes or mutant or polymerase complex of A/Puerto Rico/8/1934 (H1N1) (PR8) virus genes were replaced individually by corresponding gene of A/ chicken/ZJ/China/2013 ( H5N1) virus, and the hemagglutination titers of recombinant viruses were compared by HA assay. RESULTS: PB2 gene had the greatest influence, its replace failed to generate recombinant virus. When PB1, PA, or M gene was replaced, the titers of recombinant viruses dropped by 3.7, 3.4, 3.0 (log2), respectively. NS gene had little influence upon HA titer. When polymerase complex genes were replaced, virus titer dropped slightly to 7.6 log2, and it did not confer the same growth characteristics (8.4 log2) found when a complete polymerase complex was of PR8 origin. When amino acids of position 627 of PR8 PB2 gene were mutated to glutamic acid, virus titer rose from 8.4 log2 to 8.7 log2. CONCLUSION: The optimal gene combinations may facilitate replication through viral RNA and protein interaction with cellular components as well as interaction of viral RNA and protein or protein-protein interactions within the virus. These multi-factorial contributions resulted in selection of a high replication competent reassortant in embryonated chicken eggs in comparison to the respective low yield wild type viruses, and laid the foundation for high
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Vírus da Influenza A Subtipo H1N1/crescimento & desenvolvimento , Virus da Influenza A Subtipo H5N1/crescimento & desenvolvimento , Proteínas Virais/metabolismo , Animais , Embrião de Galinha , Galinhas , Humanos , Vírus da Influenza A Subtipo H1N1/genética , Vírus da Influenza A Subtipo H1N1/metabolismo , Virus da Influenza A Subtipo H5N1/genética , Virus da Influenza A Subtipo H5N1/metabolismo , Influenza Humana/virologia , Proteínas Virais/genéticaRESUMO
Bovine influenza virus was first identified in the USA in 2013, and the virus represents a potential novel type of influenza viruses. However, the distribution and evolution of the virus remain unknown. We conducted a pilot survey of bovine influenza virus in China, and identified three bovine influenza viruses which are highly homogenous to the ones identified in the USA, suggesting that the bovine influenza virus likely circulates widely and evolves slowly in the world.
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Doenças dos Bovinos/virologia , Infecções por Orthomyxoviridae/veterinária , Orthomyxoviridae/classificação , Orthomyxoviridae/isolamento & purificação , Animais , Bovinos , China , Análise por Conglomerados , Dados de Sequência Molecular , Orthomyxoviridae/genética , Infecções por Orthomyxoviridae/virologia , Filogenia , Análise de Sequência de DNA , Homologia de SequênciaRESUMO
Copper-based bimetallic heterojunction catalysts facilitate the deep electrochemical reduction of CO2 (eCO2RR) to produce high-value-added organic compounds, which hold significant promise. Understanding the influence of copper interactions with other metals on the adsorption strength of various intermediates is crucial as it directly impacts the reaction selectivity. In this review, an overview of the formation mechanism of various catalytic products in eCO2RR is provided and highlight the uniqueness of copper-based catalysts. By considering the different metals' adsorption tendencies toward various reaction intermediates, metals are classified, including copper, into four categories. The significance and advantages of constructing bimetallic heterojunction catalysts are then discussed and delve into the research findings and current development status of different types of copper-based bimetallic heterojunction catalysts. Finally, insights are offered into the design strategies for future high-performance electrocatalysts, aiming to contribute to the development of eCO2RR to multi-carbon fuels with high selectivity.
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Background: Sodium/glucose cotransporter-2 inhibitors (SGLT2i) are associated with cardiovascular benefits. The aim of this systematic review and meta-analysis is to summarize the influence of SGLT2i on the incidence of acute kidney injury (AKI), and to ascertain whether it is affected by confounding variables such as age, baseline renal function and concurrent use of renin-angiotensin-aldosterone system inhibitors (RAASi) or mineralocorticoid receptor antagonists (MRA). Methods: PubMed, Embase, and Cochrane Library databases were searched for randomized controlled trials comparing the influence of SGLT2i versus placebo/blank treatment on AKI in the adult population. A fixed-effect model was used if the heterogeneity was not significant; otherwise, a randomized-effect model was used. Results: Eighteen studies comprising 98,989 patients were included. Compared with placebo/blank treatment, treatment with SGLT2i significantly reduced the risk of AKI (risk ratio [RR]: 0.78, 95% confidence interval [CI]: 0.71 to 0.84, p < 0.001; I 2 = 0%). Subgroup analysis suggested consistent results in patients with diabetes, chronic kidney disease, and heart failure (for subgroup difference, p = 0.32). Finally, univariate meta-regression suggested that the influence of SGLT2i on the risk of AKI was not significantly modified by variables such as age (coefficient: 0.011, p = 0.39), baseline estimated glomerular filtration rate (coefficient: -0.0042, p = 0.13) or concomitant use of RAASi (coefficient: 0.0041, p = 0.49) or MRA (coefficient: -0.0020, p = 0.34). Conclusion: SGLT2i may be effective in reducing the risk of AKI, and the effect might not be modified by age, baseline renal function and concurrent use of RAASi or MRA.
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Dopant-induced electron redistribution on transition metal-based materials has long been considered an emerging new electrocatalyst that is expected to replace noble-metal-based electrocatalysts in natural seawater electrolysis; however, their practical applications remain extremely daunting due to their sluggish kinetics in natural seawater. In this work, we developed a facile strategy to synthesize the 3D sponge-like hierarchical structure of Ru-doped NiCoFeP nanosheet arrays derived from metal-organic frameworks with remarkable hydrogen evolution reaction (HER) performance in natural seawater. Based on experimental results and density functional theory calculations, Ru-doping-induced charge redistribution on the surface of metal active sites has been found, which can significantly enhance the HER activity. As a result, the 3D sponge-like hierarchical structure of Ru-NiCoFeP nanosheet arrays achieves low overpotentials of 52, 149, and 216 mV at 10, 100, and 500 mA cm-2 in freshwater alkaline, respectively. Notably, the electrocatalytic activity of the Ru-NiCoFeP electrocatalyst in simulated alkaline seawater and natural alkaline seawater is nearly the same as that in freshwater alkaline. This electrocatalyst exhibits superior catalytic properties with outstanding stability under a high current density of 85 mA cm-2 for more than 100 h in natural seawater, which outperforms state-of-the-art 20% Pt/C at high current density. Our work provides valuable guidelines for developing a low-cost and high-efficiency electrocatalyst for natural seawater splitting.
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Metal node engineering, which can optimize the electronic structure and modulate the composition of poor electrically conductive metal-organic frameworks, is of great interest for electrochemical natural seawater splitting. However, the mechanism underlying the influence of mixed-metal nodes on electrocatalytic activities is still ambiguous. Herein, a strategic design is comprehensively demonstrated in which mixed Ni and Co metal redox-active centers are uniformly distributed within NH2-Fe-MIL-101 to obtain a synergistic effect for the overall enhancement of electrocatalytic activities. Three-dimensional mixed metallic MOF nanosheet arrays, consisting of three different metal nodes, were in situ grown on Ni foam as a highly active and stable bifunctional catalyst for urea-assisted natural seawater splitting. A well-defined NH2-NiCoFe-MIL-101 reaches 1.5 A cm-2 at 360 mV for the oxygen evolution reaction (OER) and 0.6 A cm-2 at 295 mV for the hydrogen evolution reaction (HER) in freshwater, substantially higher than its bimetallic and monometallic counterparts. Moreover, the bifunctional NH2-NiCoFe-MIL-101 electrode exhibits eminent catalytic activity and stability in natural seawater-based electrolytes. Impressively, the two-electrode urea-assisted alkaline natural seawater electrolysis cell based on NH2-NiCoFe-MIL-101 needs only 1.56 mV to yield 100 mA cm-2, much lower than 1.78 V for alkaline natural seawater electrolysis cells and exhibits superior long-term stability at a current density of 80 mA cm-2 for 80 h.
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Dozens of human cases infected with H7N9 subtype avian influenza virus (AIV) have been confirmed in China since March, 2013. Distribution data of sexes, ages, professions and regions of the cases were analyzed in this report. The results showed that the elderly cases, especially the male elderly, were significantly more than expected, which is different from human cases of H5N1 avian influenza and human cases of the pandemic H1N1 influenza. The outbreak was rated as a Grade III (severe) outbreak, and it would evolve into a Grade IV (very severe) outbreak soon, using a method reported previously. The H7N9 AIV will probably circulate in humans, birds and pigs for years. Moreover, with the driving force of natural selection, the virus will probably evolve into highly pathogenic AIV in birds, and into a deadly pandemic influenza virus in humans. Therefore, the H7N9 outbreak has been assumed severe, and it is likely to become very or extremely severe in the future, highlighting the emergent need of forceful scientific measures to eliminate any infected animal flocks. We also described two possible mild scenarios of the future evolution of the outbreak.
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Single-atom catalysts (SACs) are regarded as promising non-noble-metal alternatives for the oxygen reduction reaction (ORR) in proton exchange membrane fuel cells due to their high atom utilization efficiency and excellent catalytic properties. However, the insufficient long-term stability issues of SACs under the working conditions seriously hinder their practical application. In this perspective, the recent progress of SACs with optimized ORR catalytic activity is first reviewed. Then, the possible degradation mechanisms of SACs in the ORR process and effective strategies for improving their ORR durability are summarized. Finally, some challenges and opportunities are proposed to develop stable single-atom-based ORR electrocatalysts in the future.
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RATIONALE: Meningeal melanocytoma is a rare benign pigmented tumor originat from leptomeningeal melanocytes. Here, we report the case of a female who presented with numbness and weakness of the limbs for approximately 6 months. PATIENT CONCERNS: We report the case of a 60-year-old Chinese female who presented with numbness and weakness of the limbs for approximately 6 months. computed tomography (CT) and magnetic resonance imaging (MRI) revealed a dumbbell-shaped tumor inside and outside the cervical (C) spinal canal. DIAGNOSES: The patient was using CT and MRI. Subsequently, the patient underwent surgery, and low-grade melanocytoma was diagnosed pathologically. INTERVENTIONS: Subsequently, the patient underwent a surgery, and the tumor was completely removed. OUTCOMES: The tumor did not recur after 6 months. CONCLUSION: This case suggested 2 "take-away" lessons: first, spinal meningeal melanocytomas may be dumbbell-shaped; and second, melanocytoma could appear as hyperintense, isointense, or hypointense on T2-weighted MRI.
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Melanoma , Neoplasias Meníngeas , Nevo Pigmentado , Neoplasias da Retina , Neoplasias Cutâneas , Adulto , Humanos , Feminino , Pessoa de Meia-Idade , Melanoma/diagnóstico por imagem , Melanoma/cirurgia , Hipestesia , Recidiva Local de Neoplasia/patologia , Melanócitos/patologia , Nevo Pigmentado/patologia , Neoplasias Meníngeas/diagnóstico por imagem , Neoplasias Meníngeas/cirurgia , Neoplasias da Retina/patologia , Imageamento por Ressonância Magnética , Neoplasias Cutâneas/patologiaRESUMO
Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) are two persistent organic pollutants harmful to human health. They induce negative effects on male reproduction by influencing male hormones, spermatogenesis, and sperm quality. However, their effects and mechanisms on human sperm capacitation and fertilization remain unclear. Here, human sperm were incubated with different concentrations of PFOS or PFOA with progesterone during capacitation. Both PFOS and PFOA inhibited human sperm hyperactivation, sperm acrosome reaction, and protein tyrosine phosphorylation levels. PFOS and PFOA decreased intracellular Ca2+ concentration in the presence of progesterone, and subsequently decreased cAMP level, and PKA activity. PFOS and PFOA increased reactive oxygen species production and sperm DNA fragmentation during the only 3 h capacitation incubation. Conclusively, PFOA and PFOS may inhibit human sperm capacitation via the Ca2+-mediated cAMP/PKA signaling pathway in the presence of progesterone, and induce sperm DNA damage through increased oxidative stress, which is not conducive to fertilization.
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Ácidos Alcanossulfônicos , Fluorocarbonos , Humanos , Masculino , Progesterona/farmacologia , Progesterona/metabolismo , Sêmen , Espermatozoides , Fluorocarbonos/toxicidade , Caprilatos/toxicidade , Transdução de Sinais , Dano ao DNA , Ácidos Alcanossulfônicos/toxicidadeRESUMO
Iron-nitrogen-carbon (FeNC) materials have emerged as a promising alternative to platinum-group metals for catalyzing the oxygen reduction reaction (ORR) in proton-exchange-membrane fuel cells. However, their low intrinsic activity and stability are major impediments. Herein, an FeN-C electrocatalyst with dense FeN4 sites on hierarchically porous carbons with highly curved surfaces (denoted as FeN4 -hcC) is reported. The FeN4 -hcC catalyst displays exceptional ORR activity in acidic media, with a high half-wave potential of 0.85 V (versus reversible hydrogen electrode) in 0.5 m H2 SO4 . When integrated into a membrane electrode assembly, the corresponding cathode displays a high maximum peak power density of 0.592 W cm-2 and demonstrates operating durability over 30 000 cycles under harsh H2 /air conditions, outperforming previously reported Fe-NC electrocatalysts. These experimental and theoretical studies suggest that the curved carbon support fine-tunes the local coordination environment, lowers the energies of the Fe d-band centers, and inhibits the adsorption of oxygenated species, which can enhance the ORR activity and stability. This work provides new insight into the carbon nanostructure-activity correlation for ORR catalysis. It also offers a new approach to designing advanced single-metal-site catalysts for energy-conversion applications.