程序变波长-高效液相色谱法同时测定果蔬中9种防腐剂

建立了柑橘、黄瓜、白菜、西红柿四种果蔬中9种防腐剂（对羟基苯甲酸甲酯、对羟基苯甲酸乙酯、对羟基苯甲酸丙酯、对羟基苯甲酸丁酯、对羟基苯甲酸异丙酯、对羟基苯甲酸异丁酯、乙萘酚、乙氧基喹、4-苯基苯酚）的程序变波长-高效液相色谱同时测定方法。样品采用乙醚提取,液-液萃取净化,以甲醇-水为流动相进行梯度洗脱,经Agilent Eclipse XDB-C18色谱柱（150mm×4.6mm,3.5μm）分离,程序化变波长检测,外标法定量。结果表明,9种防腐剂在0.5¹00.0mg/L范围内线性关系良好（r≥0.9991）;在50、200、500μg/kg三个添加水平下平均回收率为70.7%¹19.5%,相对标准偏差（RSD）为0.9%⁹.9%。该方法简便快速、准确可靠,适用于果蔬中多种防腐剂残留的同时测定。      

超高压处理对牛初乳中IgG活性的影响

牛初乳中富含营养物质和多种活性成分,尤其是IgG的含量特别高。以产犊后48h内的牛初乳为原料,研究不同的超高压处理条件对牛初乳中IgG活性的影响,采用ELISA方法检测经过超高压处理后样品中IgG的活性。结果显示,在压力500MPa、温度35℃、时间20min条件下处理牛初乳,其IgG活性提高率达到最大。      

典型物体表面温度的测量及初步计算

热特性模拟广泛应用于电力、消防、工业、医疗、安防等国民经济及军事部门,而验证是模拟软件优化发展过程中重要的一个环节;对于热特性模拟软件来说,一般通过实验验证对软件进行验证。为了有效快速地进行验证,将地面物体简单处理为CUBI及立方体模型。放置于各实验模型物体表面特征位置（面中心、中线）的热电偶可获得物体的实测温度数据,模拟软件所需的某些输入参数可以通过风速仪等相关仪器获得。通过对实验及计算数据的比较验证了该模拟软件的精确度基本符合要求,并且还发现了在模拟软件中应该注意的一些问题。     

牛干巴中降胆固醇、降亚硝酸盐乳酸菌的分离筛选及其发酵性能

以传统发酵牛干巴作为乳酸菌筛选源,分离出18株乳酸菌,通过OPA法测定降胆固醇能力,盐酸萘乙二胺比色法测定降解亚硝酸盐能力,菌株NR7对胆固醇的清除率是22.61%,培养12 h和24 h亚硝酸盐分别降解了34.177μg/m L和95.82μg/m L,在p H3.0的环境中活菌率达99.50%,对0.3%的胆盐耐受性强。因此,选择NR7作为目的菌株,进一步研究其生产适应性,能够在发酵4 h后使p H迅速降低,能够在15⁴0℃环境条件下生长,能够耐受8%的Na Cl和200 mg/kg的Na NO₂,且真空冷冻干燥后活菌率93.62%,4℃条件下保藏30 d后活菌率可达89.99%。16S rRNA分子生物学鉴定,菌株NR7为植物乳杆菌。      

白藜芦醇对小鼠脾淋巴细胞免疫调节活性的影响

研究了白藜芦醇（Res）对小鼠脾淋巴细胞免疫调节活性的影响。无菌分离小鼠脾,制备淋巴细胞,并用含10%胎牛血清的RPMI 1640培养,在培养液中分别加入刀豆蛋白A（Con A）、脂多糖（LPS）以及5、10、20、40μg/m L不同浓度的Res,经过不同时间培养后,采用MTT法检测淋巴细胞的增殖,ELISA法检测淋巴细胞分泌IL-4和IL-12的水平,流式细胞仪检测淋巴细胞的细胞周期和细胞膜表面标志。结果表明:Res能够促进小鼠脾淋巴细胞增殖,能与Con A协同促进小鼠脾淋巴细胞增殖,不能与LPS协同促进小鼠脾淋巴细胞增殖;能增强IL-4和IL-12的分泌;能提高小鼠脾淋巴细胞CD4+/CD8+的比值;能提高脾淋巴细胞周期中细胞进入S期细胞的百分率。综上,Res能增强小鼠脾淋巴细胞的免疫调节活性。      

不同干燥方法对酸枣叶中核苷类、氨基酸类及黄酮类成分的影响

为研究不同干燥方法对酸枣叶干燥过程中内在质量的影响,采用UPLC-TQ MS法和HPLC法分别建立酸枣叶中20种核苷类和23种氨基酸类,以及黄酮类成分芦丁的分析方法,并探索不同干燥方法对酸枣叶中上述组分组成及含量的影响。研究结果表明本研究所建立的分析方法简便、准确可靠;所有样品均富含核苷类、游离氨基酸类及黄酮类成分芦丁,其中核苷类成分以磷酸化产物如胞苷-5’-单磷酸、腺苷-5’-单磷酸、鸟苷-5’-单磷酸含量相对较高,游离氨基酸类成分以脯氨酸、酪氨酸、γ-氨基丁酸含量相对较高;且所有干燥加工后样品其上述成分含量均总体高于新鲜样品。依据各样品中所测定成分的含量,采用TOPSIS分析法,对不同干燥方法干燥样品的内在质量进行了综合评价,结果显示以自然晒干样品和40℃热风干燥样品品质较优,而新鲜样品及70℃热风干燥样品品质较差。以上研究结果为酸枣叶产地干燥加工过程适宜干燥工艺的确定提供了数据支撑,也为叶类药材的干燥加工提供了借鉴。      

极大平面图的结构与着色理论(3)纯树着色与唯一4-色极大平面图猜想

一个极大平面图若是从K4出发,不断地在三角面上嵌入3度顶点得到的,则称此极大平面图为递归极大平面图。唯一4-色极大平面图猜想是指：一个平面图是唯一4-可着色的当且仅当它是递归极大平面图。此猜想已有43年历史,是图着色理论中继四色猜想之后另一个著名的未解猜想。为此,该文相继深入研究了哑铃极大平面图与递归极大平面图的结构与特性,结合该系列文章(2)的扩缩运算,给出了证明唯一4-色极大平面图猜想的一种思路。     

Emerging Potential Mechanism and Therapeutic Target of Ferroptosis in PDAC: A Promising Future

Pancreatic cancer (PC) is a devastating malignant tumor of gastrointestinal (GI) tumors characterized by late diagnosis, low treatment success and poor prognosis. The most common pathological type of PC is pancreatic ductal adenocarcinoma (PDAC), which accounts for approximately 95% of PC. PDAC is primarily driven by the Kirsten rat sarcoma virus (KRAS) oncogene. Ferroptosis was originally described as ras-dependent cell death but is now defined as a regulated cell death caused by iron accumulation and lipid peroxidation. Recent studies have revealed that ferroptosis plays an important role in the development and therapeutic response of tumors, especially PDAC. As the non-apoptotic cell death, ferroptosis may minimize the emergence of drug resistance for clinical trials of PDAC. This article reviews what has been learned in recent years about the mechanisms of ferroptosis in PDAC, introduces the association between ferroptosis and the KRAS target, and summarizes several potential strategies that are capable of triggering ferroptosis to suppress PDAC progression.     

Breast Cancer Vaccine Containing a Novel Toll-like Receptor 7 Agonist and an Aluminum Adjuvant Exerts Antitumor Effects

Mucin 1 (MUC1) has received increasing attention due to its high expression in breast cancer, in which MUC1 acts as a cancer antigen. Our group has been committed to the development of small-molecule TLR7 (Toll-like receptor 7) agonists, which have been widely investigated in the field of tumor immunotherapy. In the present study, we constructed a novel tumor vaccine (SZU251 + MUC1 + Al) containing MUC1 and two types of adjuvants: a TLR7 agonist (SZU251) and an aluminum adjuvant (Al). Immunostimulatory responses were first verified in vitro, where the vaccine promoted the release of cytokines and the expression of costimulatory molecules in mouse BMDCs (bone marrow dendritic cells) and spleen lymphocytes. Then, we demonstrated that SZU251 + MUC1 + Al was effective and safe against a tumor expressing the MUC1 antigen in both prophylactic and therapeutic schedules in vivo. The immune responses in vivo were attributed to the increase in specific humoral and cellular immunity, including antibody titers, CD4⁺, CD8⁺ and activated CD8⁺ T cells. Therefore, our vaccine candidate may have beneficial effects in the prevention and treatment of breast cancer patients.