Control and regulation of mitochondrial and cellular respiration by oxygen is discussed with three aims: (1) A review of intracellular oxygen levels and gradients, particularly in heart, emphasizes the dominance of extracellular oxygen gradients. Intracellular oxygen pressure, pO2, is low, typically one to two orders of magnitude below incubation conditions used routinely for the study of respiratory control in isolated mitochondria. The pO2 range of respiratory control by oxygen overlaps with cellular oxygen profiles, indicating the significance of pO2 in actual metabolic regulation. (2) A methodologically detailed discussion of high-resolution respirometry is necessary for the controversial topic of respiratory control by oxygen, since the risk of methodological artefact is closely connected with far-reaching theoretical implications. Instrumental and analytical errors may mask effects of energetic state and partially explain the divergent views on the regulatory role of intracellular pO2. Oxygen pressure for half-maximum respiration, p50, in isolated mitochondria at state 4 was 0.025 kPa (0.2 Torr; 0.3 microM O2), whereas p50 in endothelial cells was 0.06-0.08 kPa (0.5 Torr). (3) A model derived from the thermodynamics of irreversible processes was developed which quantitatively accounts for near-hyperbolic flux/pO2 relations in isolated mitochondria. The apparent p50 is a function of redox potential and protonmotive force. The protonmotive force collapses after uncoupling and consequently causes a decrease in p50. Whereas it is becoming accepted that flux control is shared by several enzymes, insufficient attention is paid to the notion of complementary kinetic and thermodynamic flux control mechanisms.

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T-cells and monocytes are the first cells infiltrating the arterial intima during the early stages of atherogenesis. Recently our laboratory has provided evidence that T-cells isolated from atherosclerotic intima reacts against heat shock protein 60 (Hsp60). Transmigration of activated T-cells into the intima is mediated by adhesion molecules (ICAM-1; VCAM-1; ELAM-1) expressed on activated endothelial cells. Here we studied the potential of cytokines (TNF-alpha, IFN-gamma, IL-1). Escherichia coli lipopolysaccharide (LPS), native and oxidized low-density lipoprotein (LDL; oxLDL) and high temperature to induce adhesion molecules as well as Hsp60 and Hsp70 expression in human endothelial cells (EC). On Northern blots, a strong signal for ICAM-1, VCAM-1 and ELAM-1 was detected after 4 h, which thereafter declined, but did not reach the basal level of untreated control cells. Heat shock induced the expression of Hsp60 and Hsp70 but not of adhesion molecules. EC were cultivated in serum-free medium, which led to the expression of adhesion molecule transcripts. Addition of LDL or oxLDL to these ECs did not alter the expression of these transcripts. The production of adhesion molecule proteins was analysed by flow cytometry. In human venous endothelial cells (HVEC) and human arterial endothelial cells (HAEC) ICAM-1 and VCAM-1 production was permanently highly induced, whereas the high level of ELAM-1 production at 4 h disappeared after 24 h. Furthermore, only HAEC, but not HVEC, produced ICAM-1, VCAM-1 and ELAM-1 after stress by moderately and highly oxLDL. LDL and oxLDL did not induce the production of Hsp60 and Hsp70. The present study demonstrates the co-expression of Hsp60 and adhesion molecules in arterial and venous EC in response to cytokine and LPS exposure, and that oxLDL is an efficient inducer of adhesion molecules in arterial EC and not in venous EC. These features provide the prerequisites for a cellular immune reaction against Hsp60 expressed by stressed EC in the initial stages of atherosclerosis.

First-passage mass cultures of 16 million endothelial cells-required for the confluent lining of a 70 cm long 6 mm graft-were reached 25.1 +/- 11.2 days after vein excision. Growth failure occurred in 27.3%. After 32 months, the actuarial patency was 84.7% for endothelialized grafts and 55.4% for control grafts (p < 0.041 by Breslow test; p < 0.068 by Mantel-Cox test). The ankle-brachial index was continually diverging, reaching significantly lower values in the control group at 24 months (0.98 +/- 0.14 in the endothelialized group versus 0.70 +/- 0.12 in the control; p < 0.0023). The uptake of indium 111-labeled platelets--measured at 9 days, 3 months, 6 months, and 12 months--was significantly lower in the endothelialized group during the entire observation period.

Defunctioning loop ileostomy should be fashioned in rectal cancer patients with anastomoses below 6 cm, particularly in male patients, even if reconstruction was done with a J-pouch.