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Daily rhythms of light/darkness, activity/rest and feeding/fasting are important in human physiology and their disruption (for example by frequent changes between day and night shifts) increases the risk of disease. Many of the diseases found to be associated with such disrupted circadian lifestyles, including cancer, cardiovascular diseases, metabolic disorders and neurological diseases, depend on pathological de-regulation of angiogenesis, suggesting that disrupting the circadian clock will impair the physiological regulation of angiogenesis leading to development and progression of these diseases. Today there is little known regarding circadian regulation of pathological angiogenesis but there is some evidence that supports both direct and indirect regulation of angiogenic factors by the cellular circadian clock machinery, as well as by circulating circadian factors, important for coordinating circadian rhythms in the organism. Through highlighting recent advances both in pre-clinical and clinical research on various diseases including cancer, cardiovascular disorders and obesity, we will here present an overview of the available knowledge on the importance of circadian regulation of angiogenesis and discuss how the circadian clock may provide alternative targets for pro- or anti-angiogenic therapy in the future.

Colombia has one of the richest floras of any country on earth. It has a large topographic range and varied climatic regimes, and is rich in endemic species (GENTRY, 1983). Many areas of the country have been poorly collected; nevertheless, SCHULTES (1951) estimates that 50.000 species of phanerogams grow in Colombia. PRANCE (1977) cites the lower figure of 45.000, and other workers have speculated that the diversity is even lower (GENTRY, 1978). Because the study of the flora of Colombia is not yet complete it is impossible to give an accurate figure for the number of plant species occurring in the country. It is certain, however, that Colombia is tremendously rich floristically, including in its flora perhaps as much as 50% of all the flowering plant species in the Neotropics (PRANCE, 1977).