The reaction of human methaemoglobin and horse metmyoglobin with t-butyl hydroperoxide (t-BuOOH) was investigated with the ESR spin-trapping technique. With the spin trap 5,5-dimethyl-1-pyrroline N-oxide (DMPO) the formation of peroxyl, alkoxyl and methyl radicals derived from t-BuOOH could be detected. The relative contributions of these radicals were determined at various DMPO concentrations ...

Whereas the addition of four moles of zinc acetate to one of normal human haemoglobin at pH 7.4 results in a clear solution, addition to unstable haemoglobin results in precipitate formation. Within certain limits no false-positive results are obtained with methaemoglobin, and with fetal haemoglobin. With excess zinc, normal haemoglobin also precipitates, but this process is reversible and can ...

An epidemiological investigation was undertaken in India to assess the prevalence of methaemoglobinaemia in areas with high nitrate concentration in drinking-water and the possible association with an adaptation of cytochrome-b5 reductase. Five areas were selected, with average nitrate ion concentrations in drinking-water of 26, 45, 95, 222 and 459 mg/l. These areas were visited and house sched...

The generation of methaemoglobin is a rare but potential life-threatening side effect in the use of the local anaesthetic prilocaine. It is currently only possible to ensure the diagnosis by means of blood tests. Rapid noninvasive diagnosis is desirable, especially for risk patients. Using a pig model, we induced methaemoglobinemia via application of dimethyl aminophenol and prilocaine (setup I...

Cyclosporine A-treated transplant recipients develop pronounced cardiovascular disease and have increased oxidative stress and altered antioxidant capacity in erythrocytes and plasma. These experiments investigated the time-course of cyclosporine A-induced changes to redox balance in plasma and erythrocytes. Rats were randomly assigned to either a control or cyclosporine A-treated group. Treatm...

In the preceding paper, Keilin & Wang (1946) have described the preparation and properties of the haemoglobin obtained from the tracheal cells of the larva of Gastrophilus (the bot fly). Samples from three of their preparations in the form ofmethaemoglobin were used for measurements of osmotic pressure. The amount of material available was small and the results recorded must be regarded as prov...

Haemoglobin (Hb)-M Hyde Park, also known as Hb-M Akita is a rare type of hereditary Hb M due to autosomal dominant mutation of CAC>TAC on codon 92 of β globin gene resulting in the replacement of histidine by tyrosine on β globin chain. This variant Hb has a tendency to form methaemoglobin (metHb). The iron ion in metHb is oxidized to ferric (Fe3+) which is unable to carry oxygen and the patien...

AIM To assess the safety and efficacy of EMLA cream (eutectic mixture of local anaesthetics) used to induce surface anaesthesia for venepuncture in healthy preterm infants. METHODS Nineteen infants, median gestational age 31 weeks (range 26-33 weeks) were assessed in a randomised, double blind, placebo controlled, cross-over trial. Changes in physiological variables (heart rate, blood pressur...

Cyanosis is a physical finding that can occur at any age but presents a great challenge as the causes are multiple and varied. When patients present with cyanosis and dyspnoea that are unrelated to cardiopulmonary causes, methaemoglobinaemia should be considered as a possible diagnosis although rare. Methaemoglobinaemia can be asymptomatic even when methaemoglobin (metHb) levels are as high as ...