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Luigi Lazzeri Maria Grazia Cascone Simone Quiriconi Letterio Morabito Paolo Giusti 《Polymer International》2005,54(1):101-107
Biodegradable hollow microfibres containing particles loaded with specific active agents can be potentially employed to produce a special kind of substrate for tissue engineering, able to function as a scaffold and at the same time to act as a drug‐releasing system. Biodegradable hollow microfibres based on poly(lactic acid) were produced by a dry–wet spinning procedure. Drug‐loaded microparticles were prepared by a simple oil‐in‐water emulsion and entrapped inside the fibres. The morphology of both fibres and particles was investigated by scanning electron microscopy. The mechanical and thermal properties of the fibres were investigated by tensile tests and differential scanning calorimetry. In vitro tests were performed to evaluate the release of the drug from the fibres loaded with the particles Copyright © 2004 Society of Chemical Industry 相似文献
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The three-dimensional solution structure of des-[Phe(B25)] human insulin has been determined by nuclear magnetic resonance spectroscopy and restrained molecular dynamics calculations. Thirty-five structures were calculated by distance geometry from 581 nuclear Overhauser enhancement-derived distance constraints, ten phi torsional angle restraints, the restraints from 16 helical hydrogen bonds, and three disulfide bridges. The distance geometry structures were optimized using simulated annealing and restrained energy minimization. The average root-mean-square (r.m.s.) deviation for the best 20 refined structures is 1.07 angstroms for the backbone and 1.92 angstroms for all atoms if the less well-defined N and C-terminal residues are excluded. The helical regions are more well defined, with r.m.s. deviations of 0.64 angstroms for the backbone and 1.51 angstroms for all atoms. It is found that the des-[Phe(B25)] insulin is a monomer under the applied conditions (4.6 to 4.7 mM, pH 3.0, 310 K), that the overall secondary and tertiary structures of the monomers in the 2Zn crystal hexamer of native insulin are preserved, and that the conformation-averaged NMR solution structure is close to the structure of molecule 1 in the hexamer. The structure reveals that the lost ability of des-[Phe(B25)] insulin to self-associate is caused by a conformational change of the C-terminal region of the B-chain, which results in an intra-molecular hydrophobic interaction between Pro(B28) and the hydrophobic region Leu(B11)-Leu(B15) of the B-chain alpha-helix. This interaction interferes with the inter-molecular hydrophobic interactions responsible for the dimerization of native insulin, depriving the mutant of the ability to dimerize. Further, the structure displays a series of features that may explain the high potency of the mutant on the basis of the current model for the insulin-receptor interaction. These features are: a change in conformation of the C-terminal region of the B-chain, the absence of strong hydrogen bonds between this region and the rest of the molecule, and a relatively easy accessibility to the Val(A3) residue. 相似文献
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This study investigated the developmental changes in the mechanical properties of the respiratory system in growing horses. Pulmonary mechanics and lung volumes were serially measured in anesthetized foals during the first year of life. Quasi-static pressure-volume curves were generated, and functional residual capacity (FRC) was measured using a closed nitrogen equilibration technique. At birth, chest wall compliance normalized to body weight was substantially less than that reported in other less precocious newborn species, while lung compliance normalized to body weight was similar to values reported for other species. Characteristics of the transition from the neonatal to adult respiratory system in the foal included a decrease in the ratios of chest wall to lung compliance (Cw/CL) and the unstressed volume of the chest wall to TLC, and a constant FRC/TLC throughout most of the study period. The somatic growth of the foal and its respiratory system were uneven processes, with increases in lung volume lagging increases in overall body size. 相似文献
26.
EH Eddes AM Masclee HG Gooszen M Fr?lich CB Lamers 《Canadian Metallurgical Quarterly》1997,174(4):387-392
Two mobilizable cloning vectors, designated pABW1 and pAWB2, were constructed basing on the E. coli vector pBGS18 and oriT originating from RK2. In pABW2 the kanamycin resistance gene was replaced by a novel tetracycline resistance cassette derived from Tn1721. Both vectors, specific for E. coli, allow to perform the cloning steps in E. coli and then to efficiently transfer the constructs by conjugation to the host of choice. A vector which cannot propagate in the given host can be applied for identification of the host specific plasmid replicator regions. With the use of pABW2 we defined the minimal replicator region of pTAV202-a mini-derivative of the large pTAV1 plasmid of P. versutus. We also proved that RepC' encoded on this fragment is the principal initiator replication protein and that oriV is located along its coding sequence. 相似文献
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E Ashihara AM Vannucchi G Migliaccio AR Migliaccio 《Canadian Metallurgical Quarterly》1997,171(3):343-356
The Word Accentuation Test assesses the accentuation of 30 infrequent Spanish words written without the accentuation mark and is an easy-to-use tool for estimating premorbid intelligence of Spanish-speaking people. Its intraobserver (0.97) and interobserver (0.93) reliabilities and its correlation with the Wechsler Adult Intelligence Scale (.837) and Raven's Progressive Matrices (.655) are high, offering a good prediction of general intelligence. It is resistant to mental deterioration; 20 demented and 40 controls matched by sex, age, and education obtained similar scores. The discrepancies between current and predicted scores in Raven's scale can diagnose mild-moderate dementia with 0.79 accuracy (sensitivity, 0.78; specificity, 0.82). 相似文献
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OM Elashry G Giusti RB Nadler EM McDougall RV Clayman 《Canadian Metallurgical Quarterly》1997,158(2):363-369
The choline-containing phosphoglycolipid, MfGL-II, is the major polar lipid of Mycoplasma fermentans PG18. Anti-MfGL-II antisera raised in rabbits using the purified MfGL-II as an immunogen were employed in immunogold electron microscopic and immunofluorescence studies showing that MfGL-II is uniformly distributed and exposed on the cell surface of M. fermentans cells. The specificity of the antibodies was determined by immunostaining of lipid extracts separated by thin layer chromatography. The antibodies recognize lipids specific to M. fermentans but did not cross-react with lipid extracts of M. penetrans, M. capricolum, M. gallisepticum or Acholeplasma laidlawii. As phosphocholine almost completely abolished antibody interaction with MfGL-II in an ELISA assay it is suggested that the anti-MfGL-II repertoire is composed primarily of anti-phosphocholine antibodies. The anti-MfGL-II antisera inhibit the attachment of M. fermentans to Molt-3 lymphocytes suggesting that MfGL-II plays a major role in M. fermentans-host cell interaction. 相似文献
30.
The data of nine children with post-traumatic intramural haematoma of the duodenum treated in Aghia Sophia Children's Hospital of Athens from 1967 to 1980 were retrospectively analysed. Diagnosis was preoperative in all but two children, in whom diagnosis was made during laparotomy. All but one were managed by operative intervention which consisted of simple evacuation of the haematoma and closure of the serosal incision in two out of eight children. Six out of eight children operated on were followed up for 15 years, during which they were free of symptoms. Hypotonic duodenography performed in the above patients was negative for deformity or stricture of the duodenum. 相似文献