Cysteamine oxidation was shown to be catalysed by nanomolar concentrations of myeloperoxidase in a peroxidase-oxidase reaction, i.e. an O2-consuming oxidation of a compound catalysed by peroxidase without H2O2 addition. When auto-oxidation of the thiol was prevented by the metal-ion chelator diethylenetriaminepenta-acetic acid, native, but not heat-inactivated, myeloperoxidase induced changes in the u.v.-light-absorption spectrum of cysteamine. These changes were consistent with disulphide (cystamine) formation. Concomitantly, O2 was consumed and superoxide radical anion formation could be detected by Nitro Blue Tetrazolium reduction. Both superoxide dismutase and catalase inhibited the reaction, whereas the hydroxyl-radical scavengers mannitol and ethanol did not. O2 consumption increased with increasing pH (between pH 6.0 and 8.0), and 50% inhibition was exhibited by about 3 mM-NaCl at pH 7.0 and by about 100 mM-NaCl at pH 8.0. Cysteamine was about 5 times as active (in terms of increased O2 consumption at pH 7.5) as the previously reported peroxidase-oxidase substrates NADPH, dihydroxyfumaric acid and indol-3-ylacetic acid. A possible reaction pathway for the myeloperoxidase-oxidase oxidation of cysteamine is discussed. These results indicate that cysteamine is a very useful substrate for studies on myeloperoxidase-oxidase activity.

Isolated neutrophils from healthy donors were used for the isolation of four highly purified forms of myeloperoxidase as determined by spectral (A430/A280 ratio 0.80-0.87) and enzyme-activity measurements. Although the myeloperoxidases exhibited different elution profiles on cation-exchange chromatography, gel filtration indicated similar relative molecular masses. When these forms were assayed for peroxidase and peroxidase-oxidase activities with several substrates, they all exhibited virtually the same specific activities. These results suggest that possible functional differences between the enzymes may be related to differences in their sites of action rather than to differences in enzyme activity. Myeloperoxidase from a patient with chronic myeloid leukaemia also revealed a similar heterogeneity on cation-exchange chromatography. However, this myeloperoxidase contained in addition one form with a lower and one form with a higher relative molecular mass, as indicated by gel-filtration chromatography.

A preparation containing an iron-poly (sorbitol-gluconic acid) complex for parenteral treatment of iron deficiency anaemia is described. The physical and chemical properties of the iron complex have been studied by using electrophoresis and gel permeation chromatography. A rapid absorption from the injection site after intramuscular administration to rabbits takes place, 70 per cent of the iron being absorbed after 2 4 4 8 hours. Thereafter, the absorption rate is slower, and 32 days after the injection 94 per cent has been absorbed from the injection site. In rabbits the maximum level of iron in serum is reached after 12-24 hours; in dogs after 1-3 hours. Disappearance from the serum takes place slowly. The complex is exclusively absorbed via the lymphatic route. Nine to ten per cent of the given dose is excreted by the kidney within 72 hours in rats and 24 hours in rabbits after intramuscular administration. On administration of the preparation to rats, made anaemic by phlebotomy, a rapid increase of haemoglobin values is observed as well as a very high utilization of the retained amount of the given dose.

A new iron preparation for intramuscular use is described. It contains a complex of iron, sorbitol and citric acid. Its properties in comparison with several other complexes, particularly iron-dextran, have been studied. The preparation is stable in serum, is hypertonic, does not produce haemolysis, and affects coagulation only at very high concentrations, such as are reached only in vitro. Absorption from muscle takes place very rapidly; two-thirds of the iron is removed within 3 hr, and there is a very rapid increase in the serum-iron concentration. In experimental animals, the maximum level is reached after about 20 min and in man after about 2 hr. Disappearance from the serum takes place rapidly. The preparation contains a small amount of a fraction which reacts with transferrin and is dialysable. In man, about 30% of the total dose of iron is excreted through the kidneys during the first 24 hr after injection, the greater part of the excretion taking place during the first few hours.

An iron carbohydrate complex, iron‐poly (sorbitol‐gluconic acid), Ferastral®, was labelled with 59Fe, and its distribution in rats was studied. The animals were intramuscularly treated with a dose of 10 mg of iron/kg. Three groups of animals were used: group A: non‐anaemic and group B: anaemic rats, both kept on iron‐deficient diet, and group C: non‐anaemic rats kept on iron‐supplemented diet. Urinary and faecal excretion, distribution in the body and incorporation in blood of the 59Fe was followed up to 28 days. The total excretion after that time was 15%. There was a rapid initial phase followed by a slower continuous one. After 28 days group A had 25, group B 13 and group C 40% of the given dose remaining at the site of injection. The corresponding values in liver after 28 days were 7, 4 and 17% of the given dose, respectively. In blood a continuous increase was observed. At 28 days after administration 26, 43 and 17% of the given dose had been incorporated in the red blood corpuscles of the respective groups. These results show that the iron complex is absorbed from the site of injection and is utilized for haemoglobin synthesis. They also show that the disposition of the complex is influenced by the iron content of the diet.