Controlled Synthesis and Characterization of Poly[ethylene‐block‐(L,L‐lactide)]s by Combining Catalytic Ethylene Oligomerization with “Coordination‐Insertion” Ring‐Opening Polymerization

Model poly[ethylene‐block‐(L ,L ‐lactide)] (PE‐block‐PLA) block copolymers were successfully synthesized by combining metallocene catalyzed ethylene oligomerization with ring‐opening polymerization (ROP) of L ,L ‐lactide (LA). Hydroxy‐terminated polyethylene (PE‐OH) macroinitiator was prepared by means of ethylene oligomerization on rac‐dimethyl‐silylen‐bis(2‐methyl‐benz[e]indenyl)‐zirconium(IV)‐dichloride/methylaluminoxane (rac‐MBI/MAO) in presence of diethyl zinc as a chain transfer agent, and subsequent in situ oxidation with synthetic air. Poly[ethylene‐block‐(L ,L ‐lactide)] block copolymers were obtained via ring‐opening polymerization of LA initiated by PE‐OH in toluene at 100 °C mediated by tin octoate. The formation of block copolymers was confirmed by ¹H NMR spectroscopy, fractionation experiments, thermal behavior, and morphological characterization using AFM and light microscopy techniques.

     

重组免疫毒素IL3-PE38KDEL真核表达载体的构建

目的:构建大肠杆菌·毕赤酵母表达载体Ppic9k-IL3-Linker-PE38KDEL.方法:用PCR的方法扩增所需要的目的片段IL3及PE38KDEL,再通过酶切和连接的方法定向克隆到载体Ppic9k-Linker中,得到融合基因Ppic9k-IL3-Linker-PE38KDEL.重组载体经酶切,菌落PCR鉴定,DNA序列分析插入片段完全正确.结果:经限制性内切酶酶切鉴定,菌落PCR及DNA序列分析表明重组表达载体Ppic9k-IL3-Lin-ker-PE38KDEL构建成功.结论:成功地构建融合基因IL3-PE38KDEL的毕赤酵母表达载体,为后续的蛋白质的表达、纯化及功能研究奠定基础.     

Catheter-Based Therapies for Massive Pulmonary Embolism

Massive pulmonary embolism carries a high mortality rate as a result of right ventricular failure. In addition to anticoagulation, systemic thrombolysis is the standard first line of therapy for patients with life-threatening massive pulmonary embolism. Surgical embolectomy is often considered in patients with contraindications to receiving systemic thrombolysis or when thrombolysis has failed. Surgical embolectomy is not without inherent risk and limitations.Although there is a paucity of large clinical trials, available data suggests catheter-based treatment of massive pulmonary embolism restores hemodynamic stability and thus is an alternative to surgical therapy.     

Synthesis and Characterization of Hyperbranched Polyethylenes Made with Nickel‐α‐Diimine Catalysts

The polymerization of ethylene in the presence of 1,4‐bis(2,6‐diisopropylphenyl)acenaphthenediiminenickel(II) dichloride ( 1 ) and methylaluminoxane (MAO) gives hyperbranched polyethylene (HBPE) in appropriate reaction conditions. The system 1 /MAO is active in solvents like toluene or hexane at temperatures as high as 80 °C and ethylene pressures ranging from 1 to 15 atm. The polyethylenes obtained show high molecular weights (up to 467 kg · mol^?1) and more than 218 branches per 1 000 backbone carbon atoms, qualifying these materials as hyperbranched. Dynamic‐mechanical thermal analysis (DMTA) of these materials shows high β‐transitions, directly related to the branch content of these polyethylenes.

DMTA analysis of polyethylenes obtained with 1 /MAO at 0, 30, and 50 °C (corresponding to entries 1, 2 and 3).     

Cutis laxa,exocrine pancreatic insufficiency and altered cellular metabolomics as additional symptoms in a new patient with ATP6AP1-CDG

Congenital disorders of glycosylation (CDG) are genetic defects in the glycoconjugate biosynthesis. > 100 types of CDG are known, most of them cause multi-organ diseases. Here we describe a boy whose leading symptoms comprise cutis laxa, pancreatic insufficiency and hepatosplenomegaly. Whole exome sequencing identified the novel hemizygous mutation c.542 T > G (p.L181R) in the X-linked ATP6AP1, an accessory protein of the mammalian vacuolar H⁺-ATPase, which led to a general N-glycosylation deficiency. Studies of serum N-glycans revealed reduction of complex sialylated and appearance of truncated diantennary structures. Proliferation of the patient's fibroblasts was significantly reduced and doubling time prolonged. Additionally, there were alterations in the fibroblasts' amino acid levels and the acylcarnitine composition. Especially, short-chain species were reduced, whereas several medium- to long-chain acylcarnitines (C14-OH to C18) were elevated. Investigation of the main lipid classes revealed that total cholesterol was significantly enriched in the patient's fibroblasts at the expense of phophatidylcholine and phosphatidylethanolamine. Within the minor lipid species, hexosylceramide was reduced, while its immediate precursor ceramide was increased. Since catalase activity and ACOX3 expression in peroxisomes were reduced, we assume an ATP6AP1-dependent impact on the β-oxidation of fatty acids. These results help to understand the complex clinical characteristics of this new patient.     

Human mast cells present antigen to autologous CD4+ T cells

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The effects of systemic treatment with aminobisphosphonates and statins on circulating Vγ9Vδ2-T cells in patients with advanced cancer

Aminobisphosphonates (NBP) are used for treatment of metastatic bone disease. Frequently, patients undergoing NBP-treatment experience side-effects, known as acute phase response (APR), resulting from cytokine production by Vγ9Vδ2-T cells. As opposed to NBP, statins reduce intracellular phosphoantigen levels and prevent NBP-induced Vγ9Vδ2-T cell activation in vitro. We conducted a pilot study in patients with (bone-)metastasized malignancies receiving NBP-treatment and evaluated the phenotype and function of circulating Vγ9Vδ2-T cells in vivo and the effects of statins on Vγ9Vδ2-T cell responses and the associated APR. We observed reduced expression of perforin, granzyme B and HLA-DR on Vγ9Vδ2-T cells in patients treated with NBP and statins. However, statins could not prevent NBP-induced changes in circulating Vγ9Vδ2-T cell numbers or production of IFNγ and TNFα. Consistent with this, simvastatin could not prevent the occurrence of APR upon NBP-infusion. These observations call for the exploration of alternative strategies to prevent collateral APR upon NBP treatment.     

Slow isomerization step in the interaction between mouse dopamine transporter and dopamine re-uptake inhibitor N-(3-iodoprop-2E-enyl)-2beta-carbo-[3H]methoxy-3beta-(4'-methylphenyl)nortropane

The kinetics of the association and dissociation of the tritium-labeled selective and potent dopamine transporter inhibitor N-(3-iodoprop-2E-enyl)-2β-carbo-[³H]methoxy-3β-(4′-methylphenyl)nortropane ([³H]PE2I) with the transporter of mouse striatal membranes was studied. The analysis revealed that the specific binding of [³H]PE2I occurs within a homogeneous population of binding sites in these membranes. The relatively slow binding process was characterized by the pseudo-first-order rate constant k_obs. The plot of these rate constants versus free radioligand concentration was hyperbolic, demonstrating that at least two kinetically distinguishable steps can be identified in the interaction of dopamine transporter with this inhibitor. The fast and reversible binding step, characterized by dissociation constant K_A = 51 ± 23 nM, is followed by a slow but also reversible isomerization step of the complex, characterized by the isomerization rate constant k_i = (7 ± 2)10⁻² s⁻¹ and by the rate constant k_−i = (3.9 ± 0.5)10⁻³ s⁻¹ for the reverse process. This isomerization step increases the apparent affinity of the ligand and probably consists of a conformational transition of the transporter protein, induced by the inhibitor molecule.     

假单胞菌外毒素体外靶向抗肝细胞癌的实验研究

目的：构建携铜绿假单胞菌外毒素PE38基因及甲胎蛋白（AFP）启动子的重组载体,并研究其在体外对AFP阳性肝细胞癌（hepatocellularcarcinoma,HCC）的靶向杀伤作用。方法：构建重组免疫毒素表达质粒pAFP-PE38,通过转染细胞观察其作用,RT-PCR法测定PE38 mRNA表达,CCK-8法检测细胞毒性。结果：各组细胞转染质粒pAFP-PE38后仅AFP阳性的HepG2细胞表达PE38 mRNA,且形态发生改变,生长显著受抑（P〈0.01）,48 h和72 h抑制率分别为27.2%、58.3%,而AFP阴性的PC-3和HeLa细胞未受明显影响。结论：PE38基因真核表达载体可实现HCC基因治疗的靶向性和高效性,有望成为肝细胞癌靶向基因治疗的有力工具。