A surgical approach in the management of mucormycosis in a trauma patient.

Mucormycosis as a consequence of trauma is a devastating complication; these infections are challenging to control, with a fatality rate approaching 96% in immunocompromised patients. We present a case where a proactive approach was successfully employed to treat mucormycosis following complex polytrauma. Aggressive repeated surgical debridement, in combination with appropriate antifungal therapy, proved successful in this instance. In our opinion, mucormycosis in trauma mandates an aggressive surgical approach. This prevents ascending dissemination of mucormycosis and certainly reduces the risk of patient mortality as a direct result. Anti-fungal therapy should be used secondarily as an adjunct together with surgical debridement, or as an alternative when surgical intervention is not feasible.

An efficient process for production of N-acetylneuraminic acid using N-acetylneuraminic acid aldolase.

N-acetyl-D-neuraminic acid (Neu5Ac) aldolase (EC 4.1.3.3) has bee reported for synthesis of Neu5Ac,1-5 but there are no reports of processes which do not have significant drawbacks for large-scale operation. Here, Neu5Ac aldolase from an overexpressing recombinant strain of Escherichia coli has been used to develop an immobilized enzyme process for production of Neu5Ac. The enzyme was immobilized onto Eupergit-C and could be reused many times in the reaction. Base-catalyzed epimerization of N-acetyl-D-glucosamine (GlcNAc) yielded GlcNAc/N-acetyl-D-mannosamine (ManNAc) mixtures (c 4:1) which could be used directly in the aldolase reaction; however, inhibition of the enzyme by GlcNAc limited the concentration of ManNAc which could be used in the reaction by this approach. This necessitated the addition of a large molar excess of pyruvate (five- to seven-fold) to drive the equilibrium over to Neu5Ac; nevertheless, a method has been developed to remove the excess pyruvate effectively by complexation with bisulfite, thus allowing Neu5Ac to be recovered by absorption onto an anion-exchange resin. In a second approach, a method has been developed to enrich GlcNAc/ManNAc mixtures for ManNAc. ManNAc can be used at high concentrations in the reaction, thus obviating the need to use a large molar excess of pyruvate. Neu5Ac can be isolated from such reaction mixtures by a simple crystallization. This work shows the importance of integrated process solutions for the effective scale-up of biotransformation reactions.

The squalestatins, novel inhibitors of squalene synthase produced by a species of Phoma. V. Minor metabolites.

The isolation and structure determination of 3H and 13C NMR and MS of 24 novel squalestatins from cultures of Phoma sp. C2932 is described.

Enzymatic production of optically pure (2'R-cis)-2'-deoxy-3'-thiacytidine (3TC, lamivudine): a potent anti-HIV agent.

Although equipotent in terms of antiviral activity, the two enantiomers of 2'-deoxy-3'-thiacytidine (BCH 189) differ markedly in their cytotoxicity. (2'R-cis)-2'-deoxy-3'-thiacytidine (3TC) is substantially less toxic than its optical antipode, and is undergoing development for the therapy of HIV infection. Cytidine deaminase from Escherichia coli is shown here to deaminate 2'-deoxy-3'-thiacytidine enantioselectively to leave 3TC essentially optically pure. This reaction has been used to develop a process for production of 3TC in multikilogram amounts. The production of cytidine deaminase was enhanced by strain improvement, fermentation development, and finally by cloning and overexpression of the gene. The enzyme was immobilized on Eupergit-C, which allowed it to be reused many times. The biotransformation conditions were optimized so that the best use could be made of the catalyst. A robust scaleable product isolation process was developed to yield the crystalline product. Overall, yields through the resolution process of 76% were obtained. All aspects of this process are capable of substantial further scaleup with only minor modifications.