The polycyclic merochlorin A and B are complex halogenated meroterpenoid natural products with significant antibacterial activities that are produced by the marine bacterium Streptomyces sp. strain CNH-189. Here we employ heterologously produced enzymes and chemical synthesis to fully reconstitute the merochlorin biosynthesis in vitro. The interplay of a dedicated type III polyketide synthase, a prenyl diphosphate synthase, and an aromatic prenyltransferase allow formation of a highly unusual aromatic polyketide-terpene hybrid intermediate that features an unprecedented branched sesquiterpene moiety. As supported by in vivo experiments, this precursor is furthermore chlorinated and cyclized to merochlorin A and isomeric merochlorin B by a single vanadium-dependent haloperoxidase, thus completing the remarkably efficient pathway.
Summary: The most commonly used approach for a greater occipital nerve decompression is through a vertical midline incision, with multiple authors reporting favorable long-term outcomes. A transverse approach to the occipital nerves has been described, yet it does not include the use of fat flaps to insulate the decompressed nerves. In this study, we describe the use of a single transverse incision with modified “W” fat flaps to decompress both the greater and lesser occipital nerves. This allows for wider exposure of the nerves without the need for an additional incision to access the lesser occipital nerve. The described technique provides increased reach and versatility of the fat flap, allowing for coverage over a longer course of the nerve and further cephalad, close to the bony skull base. In addition, the fat flaps cover the greater occipital nerve closer to its native position, as opposed to bringing the nerve into a subcutaneous position. This, theoretically, keeps the nerve in a more protected deep position and technically makes it easier to avoid any tendency for kinking the nerves while wrapping them with the fat flap. Our experience has demonstrated that this modified technique is not only safe but also efficacious in affecting a statistically significant reduction (70% improvement, P = 0.004) in migraine headache index and HIT-6 scores. This study provides further evidence that nerve decompression for headache following the principles described by Guyuron is an efficacious and reproducible procedure and that a proper nerve decompression is effective in reducing headache.
The polycyclic merochlorin A and B are complex halogenated meroterpenoid natural products with significant antibacterial activities that are produced by the marine bacterium Streptomyces sp. strain CNH-189. Here we employ heterologously produced enzymes and chemical synthesis to fully reconstitute the merochlorin biosynthesis in vitro. The interplay of a dedicated type III polyketide synthase, a prenyl diphosphate synthase, and an aromatic prenyltransferase allow formation of a highly unusual aromatic polyketide-terpene hybrid intermediate that features an
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