ABSTRACT
This paper presents the synthesis and characterization of a polyisobutylene (PIB)-based nanostructured carbon-reinforced thermoplastic elastomer. This thermoplastic elastomer is based on a self-assembling block copolymer having a branched PIB core carrying -OH functional groups at each branch point, flanked by blocks of poly(isobutylene-co-para-methylstyrene). The block copolymer has thermolabile physical crosslinks and can be processed as a plastic, yet retains its rubbery properties at room temperature. The carbon-reinforced thermoplastic elastomer had more than twice the tensile strength of the neat polymer, exceeding the strength of medical grade silicone rubber, while remaining significantly softer. The carbon-reinforced thermoplastic elastomer displayed a high T(g) of 126 degrees C, rendering the material steam-sterilizable. The carbon also acted as a free radical trap, increasing the onset temperature of thermal decomposition in the neat polymer from 256.6 degrees C to 327.7 degrees C. The carbon-reinforced thermoplastic elastomer had the lowest water contact angle at 82 degrees and surface nano-topography. After 180 days of implantation into rabbit soft tissues, the carbon-reinforced thermoplastic elastomer had the thinnest tissue capsule around the microdumbbell specimens, with no eosinophiles present. The material also showed excellent integration into bones.
Subject(s)
Carbon/pharmacology , Elastomers/pharmacology , Nanostructures/chemistry , Plastics/pharmacology , Polyenes/pharmacology , Polymers/pharmacology , Temperature , Animals , Bone and Bones/cytology , Bone and Bones/drug effects , Cell Death/drug effects , Hydrolysis/drug effects , Implants, Experimental , Magnetic Resonance Spectroscopy , Materials Testing , Mechanical Phenomena/drug effects , Microscopy, Atomic Force , Muscles/cytology , Muscles/drug effects , Prosthesis Implantation , Rabbits , Stress, Mechanical , Surface Properties/drug effects , Thermogravimetry , Water/chemistryABSTRACT
Despite more than 20 yr of use, relative differences in health-related quality of life (HRQOL) between hemodialysis (HD) and peritoneal dialysis (PD) are not clearly known. The objective of this study was to compare self-reported HRQOL and overall health status for HD and PD patients at the initiation of dialysis therapy and 1 yr later. A prospective cohort of incident ESRD patients was enrolled between October 1995 and June 1998 at 81 outpatient dialysis units in 19 states and included 698 HD and 230 PD patients who completed a baseline CHOICE Health Experience Questionnaire. The main outcome measured was change in qualify-of-life scores from start of dialysis to 1 yr on dialysis and overall health status. Of 928 patients who completed the baseline questionnaire, 585 also completed the 12-mo questionnaire; 101 had died, 55 had received a kidney transplant, and 88 had moved to a new dialysis clinic. PD patients were slightly younger, were more likely to be white, were well-educated, were employed, were married, had less comorbidity, and had higher hematocrit. Unadjusted baseline scores showed better HRQOL for PD patients in both generic and ESRD domains (bodily pain, travel, diet restrictions, and dialysis access [P < 0.05]). At 1 yr, SF-36 scores improved, whereas some ESRD domains improved and others deteriorated. HD patients had greater improvements in two SF-36 domains (physical functioning and general health perception) than PD patients, but results were mixed for ESRD domains (PD is better for finances, HD is better for sleep and overall quality of life). HD and PD patients did not differ in change in overall health status. HD and PD are associated with similar HRQOL outcomes at 1 yr. Generic HRQOL in two domains improved more for HD patients. However, for ESRD-specific HRQOL, results were not consistent; some domains were better for PD patients whereas others were better for HD patients. In advising patients about modality choices, trade-offs should be discussed and individual preferences for specific aspects of HRQOL should be elicited.
