PubMed · 3930918
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J Heller, K J Himmelstein. 1985. Poly(ortho ester) biodegradable polymer systems.. https://doi.org/10.1016/s0076-6879(85)12033-1
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Selective activation of the ketose unit in the isomeric glycosylfructoses, palatinose, leucrose, maltulose, turanose and lactulose, with pyridinium poly(hydrogen fluoride) resulted in the almost quantitative formation of glycosylated difructose dianhydrides. The reaction preferentially involves a reactive fructofuranosyl oxocarbenium ion and is subject to stereoelectronic control. The relative amounts of isomeric spirodioxanyl oligosaccharides obtained within a series was shown to depend on the reaction conditions, especially on the hydrogen fluoride-pyridine ratio. Using suitable concentrations of hydrogen fluoride in pyridine, the reaction was easily directed to the formation of the kinetic difuranosyl or thermodynamic pyranosyl derivatives. More rigorous conditions resulted in the specific hydrolysis of one glycosidic bond in the tetrasaccharides derived from palatinose, leucrose and turanose, to yield spirodioxanyl trisaccharides.
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We compared the morphologic characteristics of muscle fiber necrosis and subsequent regeneration after injury induced by intramuscular injections of bupivacaine hydrochloride (BPVC) and a variety of solutions at acid and alkaline pH (acetic anhydride, citric acid buffer, and sodium carbonate buffer). After BPVC injection the necrotic muscle fibers were rapidly invaded by phagocytic cells, followed by active regeneration and very little fibrous scar formation. The regenerating muscle fibers increased rapidly in size and attained complete fiber type differentiation and regained their initial fiber diameter within 1 month. Both alkaline and acid solutions induced muscle fiber necrosis followed by regeneration. Fiber necrosis induced by alkaline buffers and acetic anhydride solutions above pH 5.0 produced changes quite similar to that induced by BPVC. However, injection with 0.1 M acetic anhydride at pH below 4.0 resulted in coagulative necrosis of the injured muscle with very little phagocytic infiltration with poor regenerative activity and dense fibrous tissue scarring. Thus, pH 4.0 appears to be the critical pH determining the type of muscle injury and subsequent poor phagocytic and regenerative activities. This model of acidic acetic anhydride injury may lead to the identification of factors which interfere with regeneration and cause fibrous tissue scarring in human muscular dystrophy.