Immunity in the elderly: the role of the thymus

Adjustments to lifestyle including social and medical changes have led to human populations having increased longevity in many countries, producing shifts in the population demographics. Approximately half of the increase in the world's population by 2050 may be accounted for by the prolonged survival of those over the age of 60. It is possible to age in relatively good health, but this is rare and for the majority of individuals, growing old is associated with functional impairment, an increased risk of developing a degenerative condition, an increased susceptibility to disease and an increased risk of death. The ageing human population is one of the most urgent challenges facing us today. Changes in the immune system are considered to have a critical role in the decline seen with age, since many infectious diseases may no longer kill an individual, but may contribute to more subtle overall changes. So the impact of infections in older individuals should not be measured only in terms of direct mortality rates, but also by their contribution to the 'indirect' mortality rate and to changes in the quality of life. Taking a pragmatic approach, we need to understand the drivers for immune decline if we are to consider intervening therapeutically in this process. One of the central drivers to this process is age-linked atrophy of the thymus and reversal of this process may have a considerable role in reversing immune decline.

Transcutaneous oxygen tension monitoring after successful revascularization in diabetic patients with ischaemic foot ulcers

OBJECTIVE

To monitor transcutaneous oxygen tension (TcPO2) after percutaneous transluminal angioplasty (PTA) in diabetic patients with ischaemic foot ulcers.

RESEARCH DESIGN AND METHODS

Twenty-three diabetic patients with ischaemic foot ulcers who underwent successful revascularization by PTA (SR group) were retrospectively selected. Twenty diabetic patients who underwent unsuccessful revascularization (UR group) were also included. Transcutaneous oxygen tension was measured at the dorsum of the foot before and 1 (+/- 1), 7 (+/- 1), 14 (+/- 1), 21 (+/- 1) and 28 (+/- 1) days after the surgical procedure.

RESULTS

After PTA, TcPO2 progressively improved in the SR group, reaching its peak 4 weeks after angioplasty. A concomitant decrease of cutaneous carbon dioxide tension (TcPCO2) was also observed immediately after PTA which reached the lowest levels 3 weeks later. In the UR group, TcPO2 showed a slight improvement immediately after PTA but remained stable throughout the observation, while TcPCO2 levels did not change. Finally, the percentage of SR patients with a TcPO2 > or = 30 mmHg was 38.5% 1 week after PTA, while it increased to 75% 3 weeks later.

CONCLUSION

Transcutaneous oxygen tension monitoring showed that after successful revascularization it takes 3-4 weeks for cutaneous oxygenation to improve and reach the optimal levels for wound healing. Transcutaneous carbon dioxide tension monitoring may be more useful to identify the negative outcome of a revascularization procedure. Our findings suggest that, when the surgical approach can be delayed, the best timing to perform a more aggressive debridement or minor amputations is 3-4 weeks after successful revascularization.