The thermophilic cellulase Cel5a from Fervidobacterium nodosum (FnCel5a) was conjugated with neutral, cationic, and anionic polymers of increasing molecular weights. The enzymatic activity toward an anionic soluble cellulose derivative, thermal stability, and functional chemical stability of these bioconjugates were investigated. The results suggest that increasing polymer chain length for polymers compatible with the substrate enhances the positive impact of polymer conjugation on enzymatic activity. Activity enhancements of nearly 100% were observed for bioconjugates with N,N-dimethyl acrylamide (DMAm) and N,Ndimethyl acrylamide−2-(N,N-dimethylamino)ethyl methacrylate (DMAm/DMAEMA) due to proposed polymer−substrate compatibility enabled by potential noncovalent interactions. Double conjugation of two functionally distinct polymers to wild-type and mutated FnCel5a using two conjugation methods was achieved. These doubly conjugated bioconjugates exhibited similar thermal stability to the unmodified wild-type enzyme, although enzymatic activity initially gained from conjugation was lost, suggesting that chain length may be a better tool for bioconjugate activity modulation than double conjugation.

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Hirschsprung disease (HD) is an obstructive colonic process usually diagnosed in the neonatal period. A small subset of cases are diagnosed late, present with severe constipation without enterocolitis and have low rectosigmoid disease. A transanal-only pull-through is a well-described approach but in the newborn period risks a situation whereby the transition zone is higher than the sigmoid. We present our experience with the unique patient population of older HD patients in whom the transition zone was reliably reachable via a single-stage transanal approach, performed in prone position. Patients between 2 and 6 years of age with a rectal or sigmoid transition zone and minimal proximal colonic dilation can undergo a primary transanal pull-through surgical approach.

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