The question is addressed as to whether cells which are subject to high-energy dissipation rates in agitated bioreactors show an apoptotic response. Murine hybridoma cells in batch culture were agitated in bench-scale (1-L) bioreactors without gas sparging. At an energy dissipation rate of 1.5 W m(-3) there was no apparent damage. At 320 W m(-3) cell viability declined, and increasing proportions of the dead cells displayed the morphological features of apoptosis, but necrosis also remained as a significant mechanism of death. When cells were subjected to the intensive energy dissipation rate of 1870 W m(-3) in a bioreactor without gas headspace, the cell number dropped by 50% within 2 h and a subpopulation of smaller-sized cells emerged. This excluded trypan blue but showed some apoptotic characteristics such as reduced and condensed DNA content and low F-actin content. The incidence of apoptotic activity was further demonstrated by the appearance of numerous apoptotic bodies. Analysis of the cell cycles of both small and normal size populations indicated that greater proportions of S and G2 cells had become apoptotic and there was evidence of preferential survival of G1 cells. It is suggested that two mechanisms of cell death are apparent in hydrodynamically stressful situations, but their relative expression depends on the energy dissipation rate.

Three patients presenting for elective aortic surgery were studied before operation and for up to 3 days after operation with ambulatory electrocardiographic monitoring and nocturnal pulse oximetry. Supplementary oxygen was administered for the first 2 days after operation and withdrawn on the 3rd morning after operation. Heart rate remained increased for the first 3 days after operation. Two patients developed episodes of myocardial ischaemia during the first 48 h after operation while their arterial oxygen saturation remained greater than 90%. On the third day, and during the third night after operation, both the severity and duration of myocardial ischaemia increased markedly, associated with arterial hypoxaemia. A temporal relationship between decreases in oxygen saturation and fluctuations in ST segment level were observed in the three patients.

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Background: The purpose of this study was to examine quantitatively the effect of compression stockings on venous haemodynamics at the level of the ankle. Methods: To obtain quantifiable results, a computer-controlled photoplethysmographic system was used to measure the displacement of local blood volume induced by exercise (exercise displacement volume, EDV) and by tilting the subject (tilt displacement volume, TDV). The test was repeated after application of class I compression stockings 20–30 mmHg). The ratio EDV/TDV is considered to represent the efficiency of the veno-muscular pump. Three groups of subjects were studied: a control group ( n = 8), patients with telangiectases ( n = 10) and a group with large varices ( n = 11). Results: The application of external compression had a quantifiable and beneficial effect on venous haemodynamics and was most significantly documented by an increase in veno-muscular efficiency (EDV/TDV) from 28% to 44% in the varicose vein patients. Statistically significant increases of EDV/TDV could also be identified in the telangiectatic patients and normal subjects. EDV also showed an increase with compression stockings; however, statistical significance was only reached in the varicose vein group. Conclusion: External compression (class 1 compression stockings) significantly improved venous haemodynamic indices, especially in patients with varicose veins. Quantitative photoplethysmography used in this study permits a fast, non-invasive and quantifiable evaluation of venous haemodynamics of the lower extremities.

Endothelial cell seeding is a technique that has developed over the past 15 years in response to the need for a high performance synthetic vascular graft. This review details our present knowledge of seeding and examines the various problems that have hampered its introduction into clinical practice.

In a retrospective study of critical ischaemia of the lower limb, sympathectomy appeared to be of value in the majority of patients. We therefore assessed sympathectomy by measuring skin blood flow before and after the procedure using laser Doppler flowmetry (LDF) and transcutaneous oxygen tension (TCpO2) techniques. Twenty patients underwent chemical sympathectomy and there was one surgical procedure. Measurements were performed before and 1 week after sympathectomy below the knee and on the forefoot. Symptomatic improvement occurred in 20 of 21 patients. This study demonstrates that skin blood flow in the leg and foot is improved by sympathectomy and confirms objectively our clinical impression.