Several recent studies show that the lungs infected with Pseudomonas aeruginosa are often co-colonised by oral bacteria including black-pigmenting anaerobic (BPA) Porphyromonas species. The BPAs have an absolute haem requirement and their presence in the infected lung indicates that sufficient haem, a virulence up-regulator in BPAs, must be present to support growth. Haemoglobin from micro-blee...

BACKGROUND Lidocaine is commonly used for topical anaesthesia during fibreoptic bronchoscopy (FOB) and it can cause methaemoglobinemia. The present study was undertaken to evaluate the severity of post-bronchoscopy methaemoglobinemia while using lidocaine as a topical anaesthetic agent. METHODS We prospectively studied consecutive adult patients who underwent diagnostic FOB in our institution...

Superoxide ions (O2-) oxidized oxyhaemoglobin to methaemoglobin and reduced methaemoglobin to oxyhaemoglobin. The reactions of superoxide and H2O2 with oxyhaemoglobin or methaemoglobin and their inhibition by superoxide dismutase or catalase were used to detect the formation of superoxide or H2O2 on autoxidation of oxyhaemoglobin. The rate of autoxidation was decreased at about 35% in the prese...

Catalase and methaemoglobin have very similar haem groups, which are both ferric, yet catalase decomposes hydrogen peroxide to water and oxygen very efficiently, while methaemoglobin does not. Structural studies have attributed this behaviour to their different distal environments. Here we present Fe L(2,3)-edge X-ray absorption spectra of these proteins in physiological solutions, which reveal...

Superoxide radical ions (O2-) produced by the radiolytic reduction of oxygenated formate solutions and by the xanthine oxidase-catalysed oxidation of xanthine were shown to oxidize the haem groups in oxyhaemoglobin and reduce those in methaemoglobin as in reactions (1) and (2): (see articles) Reaction (1) is suppressed by reaction (8) when [O2-]exceeds 10 muM, but consumes all the O2- generated...

Intraoperative cyanosis is most commonly caused by hypoxaemia. The anaesthetist is required to perform a rapid series of diagnostic manoeuvres and take remedial action. Occasionally methaemoglobin, sulfhaemoglobin, or haemoglobin M, undetected preoperatively, is the cause of the cyanosis. We report a case of methaemoglobinaemia secondary to dapsone ingestion that was diagnosed intraoperatively....

We found a small but significant increase in methaemoglobin concentration in 1-6 year old children after routine administration of 5 g of prilocainelignocaine cream before surgery. Although the peak methaemoglobin concentration observed was well within safe limits, the finding of an increased concentration 24 hours after administration suggests that cumulative effects may occur in children rece...

1. Menadione was found to react with both the haem groups and the beta-93 thiol groups of haemoglobin. 2. It oxidized the haem groups of oxyhaemoglobin, giving mainly methaemoglobin and a smaller amount of haemichrome. The reaction rate was decrease in the presence of catalase and markedly accelerated in the presence of superoxide dismutase. It is proposed that the overall reaction involves the...