The main aims were to: optimise the method for extracting polyamine from food and blood products; study the effect of diet (after oral loading with orange juice – a food source rich in polyamines) on blood polyamine concentrations and urinary polyamine excretion; assess the concentrations of S100β protein, NSE, GFAP and polyamines in healthy control populations; study the time profile or kinetics of polyamines, NSE, S100β protein and GFAP after acute ischaemic stroke and their relationship with stroke severity and outcome using NIHSS, mRS and BI; and study the relationship between risk factor burden, aetiological mechanisms and clinical stroke sub-types and biomarker trends. Several steps were taken to improve the quality of the acid soluble extract from red blood cells.  This led to a highly reproducible and high quality extract for HPLC analysis.  Evidence gathered from the results confirmed the absorption of the content of orange juice but this did not reflect in changes in blood polyamine concentrations.  Spermidine and spermine show significant correlation with stroke severity and functional outcome comparable to S100β protein and better than NSE and GFAP. The number of participants involved in the study is the largest ever used for any clinical assessment of polyamines in stroke but still falls short for a thorough assessment of these markers.  Challenges posed by shortage of reagents for the HPLC run remained largely unresolved until recently. Limited follow-up in the stroke study restricted the evaluation of the polyamines to short term outcome measures.