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A strategy for the synthesis of well defined poly(ethylene glycol)-block-poly(methyl methacrylate) diblock copolymers containing trityl ether acid cleavable junctions is demonstrated. This approach is achieved by using a combination of poly(ethylene glycol) macroinitiator containing a trityl ether end group, which is susceptible to acid cleavage, and atom transfer radical polymerization technique. The trityl ether linkage between blocks can be readily cleaved in solution or in solid phase under very mild acid condition, which has been confirmed by 1H NMR. These diblock copolymers have been used to successfully fabricate nanoporous thin films by acid cleavage of trityl ether junction followed by complete removal of poly(ethylene glycol) block. The fabricated nanoporous thin films may have a wide range of application such as Recessed Nanodisk-array electrode (RNE) or as a template to fabricate nanoelectrode array for senor applications.

Amyloidosis, a systemic disease characterized by the deposition of misfolded protein, is difficult to rapidly diagnose due to its wide range of symptoms. The present study reported on a case of primary amyloidosis (AL) with involvement of the gastrointestinal tract, mesentery and omentum in a 66-year-old male presenting with recurrent diarrhoea and abdominal distension. Oesophagogastroduodenoscopy and enteroscopy revealed multiple gastric ulcers and multiple protuberant lesions in the colon. Laparotomy indicated multiple nodules in the mesentery of the small intestine. Contrast-enhanced CT revealed dilation of the small bowel with pneumatosis intestinalis and positive Congo red staining of gastric mucosa and mesentery biopsy specimens confirmed amyloid deposition. Therefore, the patient was diagnosed with AL. In this case, the clinical manifestation of mesentery amyloidosis was multiple nodules and extensive peritoneal adhesions, which, to the best of our knowledge, has not been reported by any previous study.

Background Circular RNAs (circRNAs) are critical regulators of many diseases, including esophageal squamous cell carcinoma (ESCC). A recent study has shown that circLPAR3 is highly expressed in ESCC, but its role and mechanism in ESCC are still unclear. Methods The expression levels of circLPAR3, microRNA-375 (miR-375), miR-433, and high-mobility group box 1 (HMGB1) were measured by quantitative real-time polymerase chain reaction (qRT-PCR). The circular characteristic and localization of circLPAR3 were identified by Ribonuclease R (RNase R) and nuclear-cytoplasmic separation assay. Also, cell proliferation was detected by cell counting kit-8 (CCK-8) and colony formation assays. Cell migration and invasion were tested by transwell assay. Moreover, Western blot (WB) analysis was used to test the levels of proliferation and metastasis-related protein, as well as the HMGB1 protein. Besides, mice xenograft models were constructed to assess the effect of circLPAR3 on ESCC tumor growth in vivo. In addition, dual-luciferase reporter and RNA pull-down assays were used to identify the mechanism of circLPAR3. Results CircLPAR3 was upregulated in ESCC tissues and cells, and its high expression was related to the poor prognosis of ESCC patients. CircLPAR3 was a stable cyclic transcript, mainly located in the cytoplasm, and its knockdown hindered the proliferation, migration and invasion of ESCC cells and inhibited ESCC tumor growth in vivo. MiR-375/miR-433 could be sponged by circLPAR3, and their inhibitors could reverse the suppression effect of silenced circLPAR3 on ESCC progression. HMGB1 could be targeted by miR-375/miR-433, and its overexpression also could invert the inhibition effect of circLPAR3 knockdown on ESCC progression. Conclusion CircLPAR3 might play an oncogenic role in ESCC through sponging miR-375/miR-433 to promote HMGB1 expression, which might provide a theoretical basis for circLPAR3 to become a biomarker for ESCC therapy.

Autophagy plays an important role in tumor development because of its capacity to maintain energy homeostasis by recycling damaged intracellular proteins and organelles, and increased autophagy levels are reported to mediate drug resistance in many cancers. However, whether high autophagy levels negatively impact tumor cell growth is unknown. Herein, we found that cisplatin (ddp)-resistant cells were more sensitive to glutamine (Gln) deprivation than ddp-sensitive cells, and they showed significant G1 arrest and increased apoptosis rates under Gln-deficient conditions. Furthermore, ddp-resistant cells had a higher level of autophagy, which mediated ddp resistance. Further analysis indicated that Gln deficiency could trigger apoptosis by enhancing activation of the autophagy signaling pathway AMPK/ULK1 in ddp-resistant cells due to their high basal autophagy level. Interestingly, ddp-resistant cells were more sensitive to rapamycin, and rapamycin could efficiently suppress the growth of ddp-resistant cells in vivo. Taken together, our study demonstrated that ddp-resistant cells became vulnerable to Gln deprivation because of their increased level of autophagy, and for the first time, we showed that suppressing the growth of ddp-resistant cells via enhancing autophagy induction was possible with rapamycin treatment.

A direct, non-enzymatic procedure for the synthesis of thiol-functionalized polylactones was developed and optimized by using 2-mercaptoethanol, the simplest unprotected thiol-containing initiator for cationic ring-opening polymerization, catalyzed by HCl and methanesulfonic acid in dichloromethane solutions. Thiol-functionalized polylactones with a molecular weight of up to approximately 5000 Da were obtained in a controlled manner. It was observed that acid can play the dual role of activator and initiator, and for the first time, it was shown that abundant HCl and/or ambient temperature lead to the formation of undesired α-carboxy-ω-chloro-functionalized polylactones that form in parallel with the targeted thiol-functionalized ones. A plausible pathway towards the formation of chlorinated products is proposed based on an active-chain-end mechanism, and the procedure was optimized to eliminate its contribution to the polymerization process, thus allowing for the activated-monomer mechanism to prevail. Molecular weight characterization was performed using 1 H NMR and size-exclusion chromatography. The results indicate that the polymers obtained under optimized conditions possess high SH functionality and moderate polydispersity, and that ring-opening polymerization proceeded in a controlled fashion. The proposed method allows for the preparation of metal free materials readily suitable for biomedical and/or electronic applications.

PurposeTo improve the speed and precise of online monitoring and diagnosis for satellite using satellite telemetry data.Design/methodology/approach – In monitoring system, a fuzzy range which gives the probability of alarm for telemetry channels using fuzzy reasoning is outlined. A failure confidence factor is presented to modify the traditional real‐time diagnosis algorithm based on multisignal model to describe the relative failure possibility for suspected components. According to the modified real‐time diagnosis algorithm based on multisignal model, it rapidly generates the states for all the components of the system such as good, bad, suspected and unknown. Then the failure probability for suspected components is obtained by Mamdani fuzzy reasoning algorithm.Findings – The experimental results reveal that the diagnosis system can not only improve diagnosis of speed but also can improve the diagnostic precision by giving failure probability for suspected fault components which may be potential failure components.Research limitations/implications – It requires the clear fault dependency relationship between components and tests.Practical implications – A very useful method for researchers and engineers who are engaged in satellite online monitoring and diagnosis.Originality/value – This paper presents a new method combining multisignal model and fuzzy theory to give the failure probability for suspected components which improves the speed and precision for fault diagnosis.

Novel hydrophilic and thermosensitive poly(N,N-diethylacrylamide-co-2-hydroxyethyl methacrylate) resins were prepared by inverse suspension polymerization with N,N′-methylenebis(acrylamide) as a crosslinker. The effects of chemical composition and degree of crosslinking on the polymerization were investigated. The polymer resins were characterized by elemental analysis, infrared spectroscopy, differential scanning calorimetry, and scanning electron microscopy. The thermosensitivity of the crosslinked resins was demonstrated by their lower critical swelling temperatures. The swelling and deswelling volume of the beads in water varied depending on the molar fraction of the N,N-diethylacrylamide. These beads swelled extensively in a variety of common solvents. They had high loadings of functional hydroxyl groups and were used as supports in the solid-phase synthesis of an oligopeptide. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1681–1690, 2003

By free radical polymerization, we have prepared a series of water-soluble, thermosensitive copolymers based on N-isopropylacrylamide and (meth)acrylamide derivatives of cholic acid, one of the bile acids. The copolymers contained 1–7 mol-% of the (meth)acrylamide derivatives of cholic acid. The chemical composition in the copolymers was studied by NMR spectroscopy and was found to be close to the original composition of the comonomers in the feed prior to polymerization. The lower critical solution temperatures (LCST) of the polymer solutions were measured by means of differential scanning calorimetry and turbidimetry. The resulting copolymers exhibit systematic changes in their LCSTs as a function of their chemical composition, as the incorporation of hydrophobic comonomers leads to a lower LCST.

N-Demethylvancomycin, which has been clinically used in China, is one member of vancomycin group (glycopeptide) antibiotics. It differs from vancomycin only in that methyl group on the amino group of the N-terminal residue of vancomycin has been replaced by H. By reductive alkylation of N-demethylvancomycin, we synthesized N-alkyl and N,N'-dialkyl N-demethylvancomycins, which closely correlated with vancomycin in structure. The association constants of the complexes of N-demethylvancomycin and its analogues with di-N-Ac-L-Lys-D-Ala-D-Ala and the antibiotic activity against Staphylococcus aureus of the glycopeptides were determined. Results showed that N-demethylvancomycin has higher affinity for bacterial cell wall analogue di-N-Ac-L-Lys-D-Ala-D-Ala and more potent antibiotic activity against Staphylococcus aureus than vancomycin. Both N-alkylation and N,N'-dialkylation of N-demethylvancomycin reduced the affinity and antibiotic activity. The longer the alkyl groups, the less potent antibiotic activities and lower affinities have the glycopeptides. The antibiotic activities against Staphylococcus aureus of N-demethylvancomycin and its analogues roughly parallel their affinities for di-N-Ac-L-Lys-D-Ala-D-Ala.

ABA and/or ABC type triblock copolymers were synthesized by living anionic and controlled radical polymerization in which poly(methyl methacrylate) was used as central block. The structural composition of these block copolymers were determined by 1 H NMR. The block length/molecular weight and microstructure of these polymers were measured by SEC. The microstructure of resultant central alkyl methacrylate block can be tailored from highly syndiotactic to highly isotactic structure by varying the solvent and/or initiator. The thermal and rheological properties of center poly(methyl methacrylate) block and poly(styrene- b - methyl methacrylate- b - styrene) tri block copolymers were studied in detail. Introduction Block copolymers are unique materials whose characteristics may be a hybrid of the individual homopolymers. The properties of the block copolymer, such as thermal behavior, dielectric properties, and solubility, can be controlled through its composition. For example, block copolymer architecture, microstructure and sequential distribution based on poly alkyl acrylates are important parameters that impact the solubility in different solvents [1]. Synthesis of ABA type triblock copolymer can be achieved by three routes: (1) sequential monomer addition, (2) synthesis of AB diblock followed by linking reaction, and (3) successive polymerization of monomers starting from a difunctional macroinitiator. Block copolymerization of dienes and styrene can be initiated from either dienyl or styrenyl anionic species. ABA type triblock copolymers based on dienes and styrene can be synthesized in a controlled manner following above three routes. In the recent years, special attention has been focused on the synthesis of ABA triblock copolymers where the center block is based on poly alkyl methacrylate particularly in the area of polymer blends [2, 3]. Among various combinations, poly(styrene- methyl methacrylate) block copolymers are commonly used as model system, as these polymers are readily accessible, poly(styrene) and poly(methyl methacrylate) have nearly the same glass transition temperature and their physical properties are well-documented in literatures [4, 5]. Poly(styrene

Well-defined cleavable poly(styrene-block-ethylene oxide) polymers were prepared by living anioinc polymerization, using cumyl potassium as the initiator. These polymers contained an acid cleavable moiety, such as diphenyl methyl or anthracenyl methyl ether linkage, between polystyrene and poly ethylene oxide block. Atomic force microscopy (AFM) studies on the thin films illustrate the formation of nanoporous architecture due to acid cleavage of the polyethylene oxide fraction.