Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0268596 (EMA)
 2,520 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To characterize the motilin receptors present in the chicken, the effects of chicken motilin (Phe-Val-Pro-Phe-Phe-Thr-Gln-Ser-Asp-Ile-Gln-Lys-Met-Gln-Glu-Lys-Glu-Arg -Asn-Lys-Gly-Gln), Leu13 porcine motilin, canine motilin and three erythromycin derivatives (EMA, EM523, GM611) on the contractility of the chicken gastrointestinal (GI) smooth muscles were investigated in vitro and compared with those in the rabbit duodenum. In the proventriculus longitudinal and circular muscle layers, chicken motilin (3 nM-1 microM) caused an atropine- and a tetrodotoxin-sensitive contraction (EC50 = 39-49 nM), and potentiated the EFS-induced contraction without affecting the responsiveness of acetylcholine. EM523 and GM611 (3-100 microM) contracted the proventriculus longitudinal muscle, and the maximum amplitudes of contraction were about 60% of that induced by chicken motilin. Chicken motilin (0.1 nM-100 nM) also caused contraction of the ileum (EC50 = 7 nM) through direct action on the smooth muscle cells. On the other hand, erythromycin derivatives showed only a weak contractile efficacy (about 20% of the maximum response of chicken motilin) even at high concentrations (10-100 microM). The rank order of potency in the ileum was chicken motilin > canine motilin > or = Leu13 porcine motilin > > GM611 > or = EM523 > or = EMA. GM109 slightly inhibited the ideal contractions induced by Leu13 porcine motilin at 100 microM (pA2 = 3.86). In the rabbit duodenum, chicken motilin was a full agonist with the same intrinsic activity as Leu13 porcine motilin, canine motilin and the erythromycin derivatives. However, the rank order of potency (Leu13 porcine motilin > or = canine motilin > chicken motilin > GM611 > or = EM523 > EMA) was different from that in the chicken ileum. In conclusion, chicken motilin causes an excitatory response in the chicken GI tract through activation of neural (proventriculus) and smooth muscle motilin receptors (ileum). The motilin receptor present in the ileum is different from that demonstrated in the rabbit intestine, because of a different rank order of motilin peptides in producing the contraction, low contracting activity of erythromycin derivatives and low antagonistic efficacy of GM109. Different pharmacological characteristics of the mechanical response induced by motilin peptides and erythromycin derivatives between the proventriculus and the ileum are discussed.
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PMID:Functional characterization of neural and smooth muscle motilin receptors in the chicken proventriculus and ileum. 941 90

A general and facile strategy was developed to prepare biocompatible peptide side-chain polymeric materials via reversible addition-fragmentation chain transfer (RAFT) polymerization. Three new dipeptide based monomers, Boc-Phe-Phe-oxyethyl methacrylate (Boc-FF-EMA), Boc-Ile-Phe-oxyethyl methacrylate (Boc-IF-EMA) and Boc-Val-Phe-oxyethyl methacrylate (Boc-VF-EMA), were synthesized and subsequently polymerized by RAFT process to afford well-defined peptide side-chain polymers, P(Boc-dipep-EMA), with controlled molecular weight, narrow polydispersity and precise chain end functionality. Further, a monomethoxy poly(ethylene glycol) (mPEG) based macro-chain transfer agent was employed for RAFT polymerization of these monomers to prepare well defined amphiphilic block copolymers, mPEG-b-P(Boc-dipep-EMA). Subsequent deprotection of side-chain Boc groups produced pH responsive homo- and block copolymers with primary amine moieties at the side chains. The cationic surface charge of various polymeric architectures was studied using dynamic light scattering (DLS) measurements. Atomic force microscopy (AFM) was employed to investigate the self-assembly of block copolymers. The in vitro biocompatibility to HeLa cells was investigated with these polymers to confirm their minimum cytotoxicity. These polymers have great potential for the pH-sensitive delivery of small interfering RNA (siRNA) owing to their interesting phase transition behaviour and biocompatibility.
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PMID:Controlled synthesis of pH responsive cationic polymers containing side-chain peptide moieties via RAFT polymerization and their self-assembly. 3226 59