Publications by authors named "John Layman"

Background: Popliteal artery injuries (PAIs) may have amputation rates as high as 20%. This study focuses on identifying risk factors associated with major amputations following PAIs in a large single-center cohort. Additionally, we assess the impact of repairing or ligating concomitant popliteal vein injuries.

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Novel tboc-protected ionenes with M(w) exceeding 30 kDa were prepared from the step-growth polymerization of tert-butyl bis[3-(dimethylamino)propyl]carbamate and 1,12-dibromododecane. The protected ionenes yielded pH-sensitive, protonatable ionenes with pK(a) approximately 6.6 for the conjugate acid of the protonated secondary amine.

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Establishing clear structure-property-transfection relationships is a critical step in the development of clinically relevant polymers for nonviral gene therapy. In this study, we determined the influence of poly(2-dimethylaminoethyl methacrylate) (PDMAEMA) molecular weight on cytotoxicity, DNA binding, and in vitro plasmid DNA delivery efficiency in human brain microvascular endothelial cells (HBMEC). Conventional free radical polymerization was used to synthesize PDMAEMA with weight-average molecular weights ranging from 43,000 to 915,000 g/mol.

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Nonwoven fibrous membranes were formed from electrospinning lecithin solutions in a single processing step. As the concentration of lecithin increased, the micellar morphology evolved from spherical to cylindrical, and at higher concentrations the cylindrical micelles overlapped and entangled in a fashion similar to polymers in semi-dilute or concentrated solutions. At concentrations above the onset of entanglements of the wormlike micelles, electrospun fibers were fabricated with diameters on the order of 1 to 5 micrometers.

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Solutions of poly(ethylene-co-vinyl alcohol) or EVOH, ranging in composition from 56 to 71 wt% vinyl alcohol, can be readily electrospun at room temperature from solutions in 70% 2-propanol/water (rubbing alcohol). The solutions are prepared at 80 degrees C and allowed to cool to room temperature. Interestingly, the solutions are not stable at room temperature and eventually the polymer precipitates after several hours.

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Electrospun fiber mats are explored as drug delivery vehicles using tetracycline hydrochloride as a model drug. The mats were made either from poly(lactic acid) (PLA), poly(ethylene-co-vinyl acetate) (PEVA), or from a 50:50 blend of the two. The fibers were electrospun from chloroform solutions containing a small amount of methanol to solubilize the drug.

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