A natural lipopeptide of surfactin for oral delivery of insulin

Abstract

Surfactin, a natural lipopeptide produced by Bacillus, is gaining attention for potentially biomedical and pharmaceutical applications. Here, surfactin was assayed for oral delivery of insulin (INS) by its ability to bind to and promote protein to penetrate through the cell membrane. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, surfactin was found to form co-precipitates with INS to protect it from acidic and enzymatic attack in the gastrointestinal tract. Further analysis by non-reductive electrophoresis showed surfactin could bind to INS forming heteropolymers. Analysis with circular dichroism, we found this binding significantly influenced the INS structure with decreased rigid α-helix and β-turn, but with increased flexible β-sheet and random coil. The change with more flexible structure was favorable for INS to penetrate through the cell membrane. Fluorescence spectra analysis also showed surfactin could lead Phe and Tyr in the inner of INS exposed outside, further promoting INS permeabilization by improving the hydrophobic-lipophilic interactions between INS and cell membrane. As a result, the effective permeability (Peff) of INS plus surfactin was 4.3 times of that of INS alone. In vivo assay showed oral INS with surfactin displayed excellent hypoglycemic effects with a relative bioavailability of 12.48% and 5.97% in diabetic mice and non-diabetic dogs, respectively. Summary, surfactin is potential for oral delivery of INS by its role as an effective protease inhibitor and permeability enhancer.     

Fertility regulating agents from traditional Chinese medicines

Chinese scientists have capitalized on the rich flora and the ethnomedical experience in China, in their pursuit of fertility regulating agents from natural products. Discoveries range from anti-implantation agents to abortifacient and pregnancy-terminating compounds, as well as a male contraceptive. Chemistry and bioactivity of these compounds and materials are reviewed in this paper, with the hope that further research and collaboration will take place to help solve the problem of population explosion.     

四瓣技术在改良结膜囊泪囊鼻腔吻合术中的应用

目的:探讨四瓣技术在改良结膜囊泪囊鼻腔吻合术中应用的安全性及有效性。方法:回顾性临床研究。选取2017-09/2020-06在我院就诊的泪道疾病患者28例28眼作为研究对象,均行结膜囊泪囊鼻腔吻合术。术后随访6～12mo,观察患者手术效果、满意度及术后并发症情况。结果:本组患者术后荧光素钠染料排泄试验阳性率为96%(27/28),手术成功率为96%(27/28),其中治愈率为68%(19/28),好转率为28%(8/28),无效率为4%(1/28),患者总体满意度为93%(26/28)。术后并发症包括眼部异物感(28眼)、球结膜充血(11眼)、鼻腔结膜囊渗血(8眼)及泪道引流管脱出(1眼)。结论:四瓣技术用于改良结膜囊泪囊鼻腔吻合术手术成功率高,并发症少,安全有效。     

Catalytic N-methyl amidation of carboxylic acids under cooperative conditions

Amide is a fundamental group that is present in molecular structures of all domains of organic chemistry and the construction of this motif with high atom economy is the focus of the current research. Specifically, N-methyl amides are valuable building blocks in natural products and pharmaceutical science. Due to the volatile nature of methyl amine, the generation of N-methyl amides using simple acids with high atom economy is rare. Herein, we disclose an atom economic protocol to prepare this valuable motif under DABCO/Fe₃O₄ cooperative catalysis. This protocol is operationally simple and compatible with a range of aliphatic and (hetero)aromatic acids with very good yields (60–99%). Moreover, the Fe₃O₄ can be easily recovered and high efficiency is maintained for up to ten cycles.

The generation of N-methyl amides using simple acids with high atom economy is rare owning to the volatile nature of methyl amine. Herein, an atom economic protocol was disclosed to prepare this valuable motif under DABCO/Fe₃O₄ cooperative catalysis.

Amide is a fundamental group that is present in molecular structures of all domains of organic chemistry.¹ It is widely distributed in natural products, synthetic drugs and functional polymers, and is also the key chemical connection in proteins.² It has been shown that amide bond formation alone accounts for 65% of all preliminary screening reactions in the pharmaceutical industry.³ This means the generation of amide bonds with high atom efficiency is of high practical importance. And not surprisingly, ‘amide formation avoiding poor atom economy reagents’ was voted as the top challenge for organic chemistry by the ACS Green Chemistry Institute in 2007.³From synthetic point of view, the ideal way to produce amide bonds would be the direct coupling of readily available carboxylic acids and amines, but this process is thermodynamically unfavourable due to the formation of the corresponding carboxylate-ammonium salt,⁴ therefore, stoichiometric amount of coupling reagents, such as DCC, DIC, EDCI, HATU, HBTU, HCTU, SOCl₂, BOP, acid chloride etc, are generally required to sidestep thermal conditions for amide bond formation.⁵ These reagents are highly successful, but the process generally suffers from poor atom economy and side products removal issue especially in the large-scale applications.⁵ To overcome these drawbacks, “nonclassical” amide bonds formation routes were investigated.⁶ In these processes, the catalyst takes the role of a coupling reagent in generating an active ester suitable for amidation in a waste-free manner. However, these processes have not been applied in the preparation of N-methyl amides, probably because the methyl amine was delivered in its hydrochloride salt, alcoholic or aqueous form due to its volatile nature.On a different note, N-methyl amides are extensively presented in numerous natural products and pharmaceutical molecules, as shown in Fig. 1,⁷ and the methylation of amides is a promising way to improve the pharmacological property of molecules.⁸ However, the synthesis of N-methyl amides compounds relies heavily on non-catalytic approaches.^5,9 Catalytic approaches were also investigated by Hisaeda,¹⁰ Kundu,¹¹ Li,¹² Guo,¹³ Yu,¹⁴ Maruoka,¹⁵ Wang,¹⁶ Chen,¹⁷ Lamaty¹⁸ and their co-workers starting from nitriles, primiary amides, aldoximes, aldehydes, lignin, carbamoylsilane and alcohols. Until recently, Thakur,¹⁹ Marce,²⁰ Sadeghzadeh²¹ and their co-workers developed elegant N-methyl amidation approach starting from carboxylic acids under nano-MgO, diatomite Earth@IL/ZrCl₄ and Mg(NO₃)₂·6H₂O catalysis respectively, while limitations like poor substrate scope or sophisticated tailored catalyst still persist. Mindful of all the above issues, developing an N-methyl amidation process of simple carboxylic acids, which is still of great challenge in synthesis, and establishing a broad (hetero)aryl scope with high atom economy from commercial available reagents and catalysts were critical considerations in this study. Moreover, the significance of N-methyl amides combined with our interests in the development of green synthetic approaches motivated us to explore the direct coupling of the carboxylic acids and isothiocyanates. To the best of our knowledge, this is the first successful work using isothiocyanatomethane to prepare N-methyl amides.Open in a separate windowFig. 1Marketed drugs bearing N-methyl amide group.Our initial investigation begins with phenylacetic acid and isothiocyanatomethane as model substrate for condition optimization. Using acetonitrile as solvent, only trace amount of product was detected under catalyst free or p-toluenesulfonic acid (PTSA) catalysis conditions (

Analysis of circRNA‐mRNA expression profiles and functional enrichment in diabetes mellitus based on high throughput sequencing

To study the pathogenesis of diabetes mellitus (DM) and identify new biomarkers, high‐throughput RNA sequencing provides a technical means to explore the regulatory network of MD gene expression. To better elucidate the genetic basis of DM, we analysed the circRNA and mRNA expression profiles in serum samples from diabetic patients. The circRNAs and mRNAs with abnormal expression in the DM group and non‐diabetic group (NDM) were classified by RNA sequencing and differential expression analysis. The circRNA‐miRNA‐mRNA regulatory network reveals the mechanism by which competitive endogenous RNAs (ceRNAs) regulate gene expression. The biological functions and interactions of circRNA and mRNA were analysed by gene ontology (GO) enrichment and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis. Differential expression analysis showed that 441 circRNAs (366 up‐regulated, 75 down‐regulated) and 683 mRNAs (354 up‐regulated, 329 down‐regulated) were significantly differentially expressed in the DM group compared with the NDM group. Screening of the differential genes at the nodes of the interaction network showed that a single circRNA could interact with multiple miRNAs and then jointly regulate more mRNAs. In addition, the expressions of circRNA CNOT6 and AXIN1 as well as mRNA STAT3, MYD88, and B2M were associated with the progression of diabetes. Enrichment pathway analysis indicated that differentially expressed circRNA and mRNA may participate in Nod‐like receptor signalling pathway, insulin signalling pathway, sphinolipid metabolism pathway, and ribosome pathway, and play a role in the pathogenesis of diabetes. This study provides a theoretical basis for elucidating the molecular mechanism of DM occurrence and development at circRNA and mRNA levels.     

Rituximab for the treatment of refractory anti-glomerular basement membrane disease

BackgroundAnti-glomerular basement membrane (anti-GBM) disease is a rare but severe autoantibody-mediated immune disorder. The typical clinical presentation includes rapidly progressive glomerulonephritis and often concurrent pulmonary hemorrhage. The present study is aimed to investigate the therapeutic effects of rituximab either used alone or with other immunosuppressants.MethodsEight patients diagnosed with anti-GBM disease and treated with rituximab from 2014 to 2020 were retrospectively reviewed.ResultsEight patients included 5 males and 3 females with a median age of 58.5 years. They all presented severe kidney injuries and 1 patient had lung hemorrhage. At diagnosis, the median of serum creatinine was 246 µmol/L (ranging from 91 to 850 µmol/L), with 3 patients requiring dialysis. All of them received corticosteroids and plasmapheresis. Rituximab was given as either standard four weekly doses or one pulse ranging from 100 to 600 mg. After a median follow-up of 34.5 months, kidney function was partially recovered or stabilized in 5/8 (62.5%) patients, free of dialysis. Anti-GBM antibodies remained undetected in all patients during follow-up. No severe adverse effect associated with rituximab was observed.ConclusionRituximab may be an alternative therapy in the treatment of patient with severe or refractory anti-GBM disease.     

肌激动器在安氏Ⅱ类错(牙合)治疗中的应用

目的 肌激动器矫正器在安氏Ⅱ类错[牙合]患者治疗中的应用特点。方法 20名10～11岁的以下凳后缩为主的安氏Ⅱ类错[牙合]患者应用肌激动器进行矫治。男9名,女11名。每位患者治疗前拍摄头颅侧位、曲面断层及手腕骨X线片。对肌激动器治疗前后及固定矫活器治疗后的头颅侧位X光片进行18个项目的测量,并对治疗前后测量结果进行配对t检验。结果SNA、ANB、OJ、U1／SN、UL-ELine、LL-ELine等在治疗后减小,差异有显著性;SNB、Li／MP、U1／PP、U6／PP、L1／MP、L6／MP、鼻唇角及额唇角增大,差异有显著性。下颌升支、下颌体以及下颌综合长度均有增长,差异有显著性。下领平面角在正畸治疗后无显著变化。结论 肌激动器在生长发育期的Ⅱ类患者的治疗中可以减小覆盖、覆皓、改善[牙合]关系并有效的改善患者下颌后缩的面型。对于存在拥挤的Ⅱ类患者,肌激动器度二期治疗时的拔牙治疗也可以达到良好的治疗效果。     

热环境对机体功能影响的机制及防护研究进展

热环境增加高温作业人员发生热损伤的风险,充分认识热环境对高温作业人员机体的影响和危害,对提高高温作业人员防暑意识、减少作业时的职业性热损伤具有重要意义.笔者主要从热环境的定义、热环境对人体主要功能系统影响的机制、热应激的影响因素及防护研究进展进行综述,为高温作业人员对热致疾病的认识及防护提供参考.     

多节段布鲁菌性脊柱炎与脊柱结核MRI特征分析

目的 探讨多节段布鲁菌性脊柱炎(BS)及脊柱结核(ST)在MRI中的不同影像特点,从而提高早期诊断及鉴别诊断水平.方法 回顾性分析33例由临床或病理确诊为多节段BS患者、30例多节段ST患者,根据两者MRI表现,分析其发生部位、椎体形态、周围组织情况及伴随征象.结果 多节段BS患者的椎体形态、椎间盘受累、后凸畸形、死骨...     

Microstructure and Electrochemical Behavior of a 3D-Printed Ti-6Al-4V Alloy

3D printing (or more formally called additive manufacturing) has the potential to revolutionize the way objects are manufactured, ranging from critical applications such as aerospace components to medical devices, making the materials stronger, lighter and more durable than those manufactured via conventional methods. While the mechanical properties of Ti-6Al-4V parts manufactured with two major 3D printing techniques: selective laser melting (SLM) and electron beam melting (EBM), have been reported, it is unknown if the corrosion resistance of the 3D-printed parts is comparable to that of the alloy made with isothermal forging (ISF). The aim of this study was to identify the corrosion resistance and mechanisms of Ti-6Al-4V alloy manufactured by SLM, EBM and ISF via electrochemical corrosion tests in 3.5% NaCl solution, focusing on the effect of microstructures. It was observed that the equiaxed α + β microstructure in the ISF-manufactured Ti-6Al-4V alloy had a superior corrosion resistance to the acicular martensitic α′ + β and lamellar α + β microstructures of the 3D-printed samples via SLM and EBM, respectively. This was mainly due to the fact that (1) a higher amount of β phase was present in the ISF-manufactured sample, and (2) the fraction of phase interfaces was lower in the equiaxed α + β microstructure than in the acicular α′ + β and lamellar α + β microstructures, leading to fewer microgalvanic cells. The lower corrosion resistance of SLM-manufactured sample was also related to the higher strain energy and lower electrochemical potential induced by the presence of martensitic twins, resulting in faster anodic dissolution and higher corrosion rate.