Development and validation of a sensitive ultra-high-performance liquid chromatography-tandem mass spectrometry method for quantitative analysis of bambermycin in livestock and aquatic products: Implications for food safety control and regulatory enforcement

A sensitive and accurate analytical method was developed and validated to detect bambermycin, a commonly used antibiotic in animal feed and livestock. The presence of bambermycin residues in food products can pose health risks to consumers, emphasizing the need for a sensitive and accurate analytical method. A reversed-phase analytical column was utilized with a mobile phase comprising 0.005 mol/L ammonium acetate in 5% acetonitrile (A) and 0.005 mol/L ammonium acetate in 95% acetonitrile (B) to achieve effective chromatographic separation. Quantitative determination of bambermycin in various samples, including beef, pork, chicken, milk, eggs, flatfish, eel, and shrimp, was performed using ultra-high-performance liquid chromatography-tandem mass spectrometry. Sample extraction involved a mixture of methanol and a 25% ammonium hydroxide solution, followed by low-temperature purification and phospholipid removal utilizing a Phree cartridge. The method exhibited a satisfactory recovery rate ranging from 69% to 100%. Validation results demonstrated the reliability, robustness, and accuracy of the method, exhibiting good linearity, precision, and recovery. This validated method can be applied for routine analysis of bambermycin residues, assisting in the development of effective monitoring and control measures to ensure the safety of livestock and aquatic products.     

Infection Microenvironment-Sensitive Photothermal Nanotherapeutic Platform to Inhibit Methicillin-Resistant Staphylococcus aureus Infection

Methicillin-resistant Staphylococcus aureus (MRSA) can induce multiple inflammations. The biofilm formed by MRSA is resistant to a variety of antibiotics and is extremely difficult to cure, which seriously threatens human health. Herein, a nanoparticle encapsulating berberine with polypyrrole core and pH-sensitive shell to provide chemo-photothermal dual therapy for MRSA infection is reported. By integrating photothermal agent polypyrrole, berberine, acid-degradable crosslinker, and acid-induced charge reversal polymer, the nanoparticle exhibited highly efficient MRSA infection treatment. In normal uninfected areas and bloodstream, nanoparticles showed negatively charged, demonstrating high biocompatibility and excellent hemocompatibility. However, once arriving at the MRSA infection site, the nanoparticle can penetrate and accumulate in the biofilm within 2 h. Simultaneously, berberine can be released into biofilm rapidly. Under the combined effect of photothermal response and berberine inhibition, 88.7% of the biofilm is removed at 1000 µg mL⁻¹. Moreover, the nanoparticles have an excellent inhibitory effect on biofilm formation, the biofilm inhibition capacity can reach up to 90.3%. Taken together, this pH-tunable nanoparticle can be employed as a new generation treatment strategy to fight against the fast-growing MRSA infection.     

不同微波膨胀烟梗的化学感官特性研究

研究不同来源包括产地、部位、年份、品种的烟梗原料经相同的微波膨胀工艺处理后的常规化学成分、致香成分、主流烟气(主要包括抽吸口数、焦油、烟碱及一氧化碳释放量)及感官特性差异,指导微波膨胀梗丝在产品中的配伍应用,为建立不同来源微波膨胀梗原料的品质特征评价体系及微波膨胀梗丝的工业应用提供依据。结果表明:不同产地来源的微波膨胀梗丝常规化学成分、致香成分、主流烟气存在差异。不同年份的微波膨胀梗丝间感官质量无明显差异,不同产地、品种、部位来源的微波膨胀梗丝总体感官质量存在差异。     

Fast Photoresponse and Long Lifetime UV Photodetectors and Field Emitters Based on ZnO/Ultrananocrystalline Diamond Films

We have designed photodetectors and UV field emitters based on a combination of ZnO nanowires/nanorods (ZNRs) and bilayer diamond films in a metal–semiconductor–metal (MSM) structure. The ZNRs were fabricated on different diamond films and systematic investigations showed an ultra‐high photoconductive response from ZNRs prepared on ultrananocrystalline diamond (UNCD) operating at a lower voltage of 2 V. We found that the ZNRs/UNCD photodetector (PD) has improved field emission properties and a reduced turn‐on field of 2.9 V μm^?1 with the highest electron field emission (EFE) by simply illuminating the sample with ultraviolet (UV) light. The photoresponse (I_photo/I_dark) behavior of the ZNRs/UNCD PD exhibits a much higher photoresponse (912) than bare ZNRs (229), ZNRs/nanocrystalline diamond (NCD; 518), and ZNRs/microcrystalline diamond (MCD; 325) under illumination at λ=365 nm. A photodetector with UNCD films offers superior stability and a longer lifetime compared with carbon materials and bare ZNRs. The lifetime stability of the ZNRs/UNCD‐based device is about 410 min, which is markedly superior to devices that use bare ZNRs (92 min). The ZNRs/UNCD PD possesses excellent photoresponse properties with improved lifetime and stability; in addition, ZNRs/UNCD‐based UV emitters have great potential for applications such as cathodes in flat‐panel displays and microplasma display devices.     

Fe(NO3)3·9H2O-catalyzed aerobic oxidation of sulfi des to sulfoxides under mild conditions with the aid of trifl uoroethanol

Selective oxidation of sulfides to sulfoxides was successfully performed by employing readily available Fe(NO3)3·9H2O as the active catalyst with oxygen as the oxidant in 2,2,2-trifluoroethanol (TFE) without the formation of sulfones. Nitrate anion could play a crucial role in promoting the reaction due to the oxidation capacity under acidic media. High yields of sulfoxides were exclusively obtained from the corresponding sulfides. Furthermore, both aromatic and aliphatic sulfides gave moderate to high yields of sulfoxides with this protocol.     

Analyses of the TCR repertoire of MHC class II-restricted innate CD4+ T cells

Analysis of the T-cell receptor (TCR) repertoire of innate CD4⁺ T cells selected by major histocompatibility complex (MHC) class II-dependent thymocyte–thymocyte (T-T) interaction (T-T CD4⁺ T cells) is essential for predicting the characteristics of the antigens that bind to these T cells and for distinguishing T-T CD4⁺ T cells from other types of innate T cells. Using the TCR^mini Tg mouse model, we show that the repertoire of TCRα chains in T-T CD4⁺ T cells was extremely diverse, in contrast to the repertoires previously described for other types of innate T cells. The TCRα chain sequences significantly overlapped between T-T CD4⁺ T cells and conventional CD4⁺ T cells in the thymus and spleen. However, the diversity of the TCRα repertoire of T-T CD4⁺ T cells seemed to be restricted compared with that of conventional CD4⁺ T cells. Interestingly, the frequency of the parental OT-II TCRα chains was significantly reduced in the process of T-T interaction. This diverse and shifted repertoire in T-T CD4⁺ T cells has biological relevance in terms of defense against diverse pathogens and a possible regulatory role during peripheral T-T interaction.     

Fetal hematopoietic stem cells express MFG-E8 during mouse embryogenesis

The milk fat globule-EGF-factor 8 protein (MFG-E8) has been identified in various tissues, where it has an important role in intercellular interactions, cellular migration, and neovascularization. Previous studies showed that MFG-E8 is expressed in different cell types under normal and pathophysiological conditions, but its expression in hematopoietic stem cells (HSCs) during hematopoiesis has not been reported. In the present study, we investigated MFG-E8 expression in multiple hematopoietic tissues at different stages of mouse embryogenesis. Using immunohistochemistry, we showed that MFG-E8 was specifically expressed in CD34⁺ HSCs at all hematopoietic sites, including the yolk sac, aorta-gonad-mesonephros region, placenta and fetal liver, during embryogenesis. Fluorescence-activated cell sorting and polymerase chain reaction analyses demonstrated that CD34⁺ cells, purified from the fetal liver, expressed additional HSC markers, c-Kit and Sca-1, and that these CD34⁺ cells, but not CD34⁻ cells, highly expressed MFG-E8. We also found that MFG-E8 was not expressed in HSCs in adult mouse bone marrow, and that its expression was confined to F4/80⁺ macrophages. Together, this study demonstrates, for the first time, that MFG-8 is expressed in fetal HSC populations, and that MFG-E8 may have a role in embryonic hematopoiesis.     

Clinicopathological values of NBS1 and DNA damage response genes in epithelial ovarian cancers

Epithelial ovarian cancers (EOCs) are highly lethal gynecological malignancies with a high recurrence rate. Therefore, developing prognostic markers for recurrence after chemotherapy is crucial for the treatment of ovarian cancers. As ovarian cancers frequently respond to DNA-damaging agents, we assessed the clinicopathological significance of key double-strand DNA break (DSB) repair genes, including BRCA1, BRCA2, BARD1, ATM, RAD51 and NBS1 in EOC cell lines and paraffin-embedded tissue sections from 140 EOC patients treated with cytoreductive surgery, followed by platinum-based chemotherapy. These samples were analyzed for the clinicopathological impact of DSB genes by western blot analysis, immunohistochemistry and quantitative real-time PCR. Of the DSB repair genes, BRCA1, ATM and NBS1, which are involved in the homologous recombination-mediated repair pathway, were related to aggressive parameters in EOC. When survival analysis was performed, NBS1 expression exhibited an association with EOC recurrence. Specifically, increased NBS1 expression was found in 107 out of 140 cases (76.0%) and correlated with advanced stage (P=0.001), high grade (P=0.001) and serous histology (P=0.008). The median recurrence-free survival in patients with positive and negative expression of NBS1 was 30 and 78 months, respectively (P=0.0068). In multivariate analysis, NBS1 was an independent prognostic factor for the recurrence of EOC. Together, these results suggest that NBS1 is a marker of poor prognosis for the recurrence of EOC and is associated with aggressive clinicopathological parameters.