Glucose Metabolism in Cancer and Ischemia: Possible Therapeutic Consequences of the Warburg Effect.

The Warburg effect states that the main source of energy for cancer cells is not aerobic respiration, but glycolysis-even in normoxia. The shift from one to the other is governed by mutually counteracting enzymes: pyruvate dehydrogenase and pyruvate dehydrogenase kinase (PDK). Anaerobic metabolism of cancer cells promotes cell proliferation, local tissue immunosuppression, resistance to hypoxic conditions, and metastatic processes. By switching glucose back to oxidative metabolism, these effects might be reversed. This can be achieved using PDK inhibitors, such as dichloroacetate. Patients suffering from ischemic conditions might benefit from this effect. On the other hand, the ß-blockers (adrenergic ß-antagonists) often used in these patients appear to improve cancer-specific survival, and nonselective ß-blockers have been shown to promote glucose oxidation. Might there be a link?

Red blood cell transfusion and skeletal muscle tissue oxygenation in anaemic haematologic outpatients.

BACKGROUND: Stored red blood cells (RBCs) accumulate biochemical and biophysical changes, known as storage lesion. The aim of this study was to re-challenge current data that anaemia in chronically anaemic haematology patients is not associated with low skeletal muscle tissue oxygen (StO2), and that RBC storage age does not influence the tissue response after ischaemic provocation, using near-infrared spectroscopy. PATIENTS AND METHODS: Twenty-four chronic anaemic haematology patients were included. Thenar skeletal muscle StO2 was measured at rest (basal StO2), with vascular occlusion testing (upslope StO2, maximum StO2) before and after transfusion. RESULTS: Basal StO2 was low (53% ± 7%). Average RBC storage time was 10.5 ± 3.9 days. Effects of RBC transfusions were as follows: basal StO2 and upslope StO2 did not change significantly; maximum StO2 increased compared to baseline (64 ± 14% vs. 59 ± 10%, p = 0.049). Change of basal StO2, upslope StO2 and maximum StO2 was negatively related to age of RBCs. The decrease of maximum StO2 was predicted (sensitivity 70%, specificity 100%), after receiving RBCs ≥ 10days old. DISCUSSION: Resting skeletal muscle StO2 in chronic anaemic patients is low. RBC storage time affects skeletal muscle StO2 in the resting period and after ischaemic provocation.