In animal experiments brief cerebral ischaemia protects against the injurious effects of prolonged subsequent ischaemia, a phenomenon known as ischaemic preconditioning. Now researchers in Oregon (

) have used RNA microarray analysis on mouse brains to show that preconditioning alters gene activity. Injurious ischaemia (middle cerebral artery occlusion for 60 mins) induced upregulation of gene expression whereas with preconditioning (occlusion for 15 mins) followed by injurious ischaemia there was downregulation of gene activity. The downregulated genes were important for glucose metabolism, protein turnover, cell-cycle regulation, and ion-channel abundance. Genes involved in hypocoagulation were upregulated. The changes are similar to those involved in hibernation. It is hoped that such research might lead to therapeutic neuroprotection.

After infectious mononucleosis the risk of Hodgkin’s lymphoma is increased but it is not known whether the association is causal. Data from Denmark and Sweden (

) suggest that it probably is. The study included 38555 people who had had infectious mononucleosis and 24 614 who had not. Forty-six subjects developed post-infectious-mononucleosis Hodgkin’s disease and 16 of 29 tumours from these subjects tested positive for Epstein-Barr virus (EBV). The risk of EBV-positive Hodgkin’s lymphoma was increased fourfold after infectious mononucleosis. There was no increase in EBV-negative Hodgkin’s lymphoma. Average time lapse from infectious …