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- Numata, Keiji, et al.
(författare)
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Branched poly(lactide) synthesized by enzymatic polymerization : effects of molecular branches and stereochernistry on enzymatic degradation and alkaline hydrolysis
- 2007
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Ingår i: Biomacromolecules. - : American Chemical Society (ACS). - 1525-7797 .- 1526-4602. ; 8:10, s. 3115-3125
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Tidskriftsartikel (refereegranskat)abstract
- In this article the effects of the number of molecular branches (chain ends) and the stereochemistry of poly(lactide)s (PLAs) on the enzymatic degradation and alkaline hydrolysis are studied. Various linear and branched PLAs were synthesized using lipase PS (Pseudomonas fluorescens)-catalyzed ring-opening polymerization (ROP) of lactide monomers having different stereochemistries (L-lactide, D-lactide, and D,L-lactide). Five different alcohols were used as initiators for the ROP, and the monomer-to-initiator molar feed ratio was varied from 10 to 100 and 1000 for each branch in the polymer architecture. The properties of branched PLAs that would affect the enzymatic and alkaline degradations, i.e., the glass transition temperature, the melting temperature, the melting enthalpy, and the advancing contact angle, were determined. The PLA films were degraded using proteinase K or 1.0 M NaOH solution, and the weight loss and changes in the number average molecular weight (M-n) of the polymer were studied during 12 h of degradation. The results suggest that an increase in the number of molecular branches of branched PLAs enhances its enzymatic degradability and alkali hydrolyzability. Moreover, the change in M-n of the branched poly(L-lactide) (PLLA) by alkaline hydrolysis indicated that the decrease in M-n was in the first place dependent on the number of molecular branches and thereafter on the length of the molecular branch of branched PLA. The branched PLLA, poly(D-lactide) (PDLA), and poly(D,L-lactide) (PDLLA) differed in weight loss and change in M-n of the PLA segment during the enzymatic degradation. It is suggested that the branched PDLLA was degraded preferentially by proteinase K.
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| 2. |
- Pawlaczyk, K, et al.
(författare)
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Vascular endothelial growth factor in dialysate in relation to intensity of peritoneal inflammation
- 2008
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Ingår i: The International journal of artificial organs. - : SAGE Publications. - 0391-3988 .- 1724-6040. ; 31:6, s. 535-544
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Tidskriftsartikel (refereegranskat)abstract
- Peritoneal inflammation may induce changes in peritoneal microvessels, including neoangiogenesis/vasculogenesis, leading to increased peritoneal solute transport rate (PSTR) and loss of ultrafiltration capacity. We hypothesized that an inflammatory reaction in the peritoneal cavity during peritonitis induces increased synthesis of vascular endothelial growth factor (VEGF). We therefore studied the relationship between peritoneal inflammation markers, VEGF, and transport of fluid and solutes in rats during acute peritoneal inflammation induced by lipopolysaccharide (LPS) added to standard glucose-based dialysis solution. Methods Under ether anesthesia, male Wistar rats were injected intraperitoneally with 30 mL Dianeal 3.86% without (Control; n=6) or with LPS (μg/mL): 0.001 (LPS 0.001; n=6), 0.01 (LPS 0.01; n=7), 0.1 (LPS 0.1; n=7), 1.0 (LPS 1.0; n=8). After 8 hours, dialysate volume (IPV), peritoneal solute transport rate (PSTR) and dialysate cell count (DCC) were measured and effluent samples were collected. Results LPS i.p. resulted in increased PSTR and decreased IPV (p<0.005). DCC (cells/μL) and the neutrophil/macrophage ratio were higher for all LPS concentrations compared to the control group. After 8 hours, LPS-exposed rats had significantly higher dialysate levels of all investigated cytokines (TNF-α, MCP-1 and IL-10) than the control group. Addition of LPS resulted in increased dialysate VEGF concentrations (pg/mL) (LPS 0.001, 28.2±5.9; LPS 0.01, 38.9±11.6; LPS 0.1, 43.0±5.9; LPS 1.0, 46.6±11.3; Control, 14.5±9.8; p<0.0005 for all LPS vs. Control). Conclusions The infusion of Dianeal 3.86% with different doses of LPS induced a strong acute intraperitoneal inflammatory reaction with increased DCC and cytokine levels, resulting in increased peritoneal solute transport and decreased IPV LPS induced a dose-dependent parallel increase of the intraperitoneal concentrations of MCP-1, IL-10 and TNF-α, as well as of VEGF. These results suggest that intraperitoneal VEGF synthesis is induced in response to inflammation, and that this may be an important component in the process leading to peritoneal transport alterations.
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