Remission of paroxysmal atrial fibrillation with iron reduction in haemophilia A.

SUMMARY: Two male first cousins with mild haemophilia A had baseline factor VIII levels of 12-15% and experienced bleeding requiring coagulation factor infusion therapy with trauma and surgical procedures. Both the patients with haemophilia A also had electrocardiographically documented symptomatic paroxysmal atrial fibrillation (PAF) for several years that had become resistant to pharmacological suppression. Radiofrequency ablation was considered in both the cases but deferred considering refusal of consent by the patients to undergo the procedure. Remission of arrhythmias has been reported in patients with iron-overload syndromes. Body iron stores assessed by serum ferritin levels were elevated in both men but neither had the C282Y or H63D genes for haemochromatosis. Calibrated reduction of iron stores by serial phlebotomy, avoiding iron deficiency, was followed by remission of symptomatic PAF in both cases. Iron reduction may be an effective treatment for arrhythmias apart from the classic iron-overload syndromes and deserves further study particularly in patients with bleeding disorders who might be at risk for arrhythmias and other diseases of ageing.

Presence of insulin binding sites on viral particles.

Using a standard radio-receptor assay, we have demonstrated that [125I]insulin can bind specifically to each of two types of purified enveloped viruses, influenza A virus and Rous sarcoma virus. A non-enveloped icosahedral virus (echovirus 11) and herpes simplex virus type 2, which acquires its envelope from the nuclear membrane of the cell, did not possess insulin receptor activity. Displacement of specifically bound radiolabelled insulin from the viral surface was achieved by addition of an excess of unlabelled insulin but not by addition of another unrelated protein, cytochrome C. We conclude that certain types of enveloped viruses may acquire insulin binding sites from the plasma membrane of their host cell.