Some electron-transfer reactions involving carbodi-imide-modified cytochrome c

Intrathecal or intraventricular antimicrobial therapy for post-neurosurgical Gram-negative bacillary meningitis or ventriculitis: a systematic review and meta-analysis

PURPOSE

Extensively-drug-resistant Gram-negative bacteria (XDR GNB)-related post-neurosurgical infection is closely related to mortality, which represents a major challenge for neurosurgeons. There is an urgent need to review and evaluate methods to reduce mortality.

METHODS

Both international and Chinese databases were searched independently from their inception to 15 June 2023. A meta-analysis was conducted using RevMan 5.4 to compare the efficacy and safety of intravenous (IV) treatment in combination with intrathecal or intraventricular (ITH/IVT) treatment with IV treatment alone for post-neurosurgical meningitis or ventriculitis due to GNB. Mortality, microbiological clearance and adverse events were considered as primary outcomes.

RESULTS

In total, 18 eligible studies involving 602 patients were included in the meta-analysis. The IV + ITH/IVT group was associated with significantly lower mortality (especially in the XDR GNB subgroup) and acceptable safety. In terms of microbiological clearance, a significant decrease was shown in the XDR GNB subgroup. Significant benefits were shown in laboratory parameters and clinical symptoms after patients were treated with ITH/IVT.

CONCLUSION

Additional ITH/IVT treatment may promote XDR GNB clearance and reduce mortality. In addition, ITH/IVT administration can improve clinical symptoms and cerebrospinal fluid indicators of patients with post-neurosurgical infections. Significantly, ITH/IVT treatment does not increase the incidence of adverse events at the recommended dose.

Some reactions of carbon monoxide and oxygen with carbodi-imide-modified cytochrome c

The reactivity of carbodi-imide-modified tuna and horse heart cytochromes c with the ferrous ion ligands CO and O2 has been studied. Both modified cytochromes bind one molecule of CO. Stopped-flow and flash-photolysis experiments indicate the presence of three kinetic processes in the reaction of the cytochromes with CO. The second-order rate constants associated with all three kinetic process are pH-independent being 2.8 x 10(5) M-1.s-1, 3.8 x 10(4) M-1.s-1 and 4 x 10(3) M-1.s-1 under all conditions studied. The concentration-dependence of the contributions made by each of the processes to the overall absorbance change indicates that the fast and slow kinetic phases are associated with two forms of the cytochromes which are in equilibrium, whereas the intermediate phase arises from a separate cytochrome species. The quantum yield for the photodissociation of CO from the ferrous cytochromes is unusually low. Both modified cytochromes are capable of binding and reducing O2. In the presence of excess reductant, the modified cytochromes can catalytically reduce large molar excesses of O2. In the absence of excess reducing agent, the oxy complex initially formed undergoes a pH-dependent intramolecular electron-transfer process with half-life approx. 10 min. EDC [1-ethyl-3-(3-dimethylaminopropyl)carbodi-imide]-promoted internal cross-linking is proposed to account for differences between the EDC-modified proteins and carboxymethylated cytochrome c.