Biosynthesis of iron-sulphur clusters is a complex and highly conserved process.

Iron-sulphur ([Fe-S]) clusters are simple inorganic prosthetic groups that are contained in a variety of proteins having functions related to electron transfer, gene regulation, environmental sensing and substrate activation. In spite of their simple structures, biological [Fe-S] clusters are not formed spontaneously. Rather, a consortium of highly conserved proteins is required for both the formation of [Fe-S] clusters and their insertion into various protein partners. Among the [Fe-S] cluster biosynthetic proteins are included a pyridoxal phosphate-dependent enzyme (NifS) that is involved in the activation of sulphur from l-cysteine, and a molecular scaffold protein (NifU) upon which [Fe-S] cluster precursors are formed. The formation or transfer of [Fe-S] clusters appears to require an electron-transfer step. Another complexity is that molecular chaperones homologous to DnaJ and DnaK are involved in some aspect of the maturation of [Fe-S]-cluster-containing proteins. It appears that the basic biochemical features of [Fe-S] cluster formation are strongly conserved in Nature, since organisms from all three life Kingdoms contain the same consortium of homologous proteins required for [Fe-S] cluster formation that were discovered in the eubacteria.

Pump-regulated lumbar subarachnoid drainage.

OBJECTIVE: The diversion of cerebrospinal fluid (CSF) has been widely used in the prevention and treatment of CSF fistulae. A common method is the use of a lumbar drainage system. Although it is effective, several serious complications can develop, which can be avoided by regulating the flow of CSF with a standard intravenous infusion pump. TECHNIQUE: We present a simple, inexpensive, and accurate method of flow-controlled lumbar subarachnoid drainage that minimizes patient discomfort and the unpredictability of a gravity-dependent system. This system uses a standard lumbar drain connected to an intravenous infusion pump to provide drainage of CSF in a constant and predictable manner. RESULTS: A total of 42 patients from two institutions were treated with this method. CSF fistulae occurred secondary to trauma in 9 patients, after spinal surgery in 11 patients, after transsphenoidal surgery in 10 patients, and after cranial base surgery in 12 patients. Resolution of the fistula was attained in 36 of 42 patients. There were no deaths, no cases of deep venous thrombosis, and no incidence of meningitis. One patient developed tension pneumocephalus, and two patients developed headache with nausea and vomiting. All patients were ambulatory, and only three patients required narcotic analgesia for headaches. CONCLUSION: Pump-regulated lumbar subarachnoid drainage is safe and effective in the treatment of CSF fistulae, as reported elsewhere in the literature. The advantage of this method is that the drainage of CSF can be carefully controlled and titrated in a predictable fashion. Because the system is independent of gravity to produce drainage of CSF, patients are not confined to bed and serious complications of overdrainage can be avoided.