Angiogenesis is a key component of the repair mechanisms triggered by tissue injury. Vascular endothelial growth factor (VEGF) is an important mediator of angiogenesis, as it acts directly and specifically on endothelial cells. VEGF produced locally in regenerating tissue may spill over into the systemic circulation, and measuring levels of circulating VEGF may allow monitoring of angiogenesis. To determine whether circulating VEGF is increased after severe injury, we measured concentrations of VEGF in serial serum samples of 23 mechanical burn patients, 55 patients with multiple trauma and 56 healthy normal controls, using a newly established ELISA assay. In burn patients, serum VEGF was increased on day 1 (369.4 +/- 88.0 pg/ml) and on day 3 (452.0 +/- 65.3 pg/ml), reached highest levels on day 14 (1809.5 +/- 239.7 pg/ml) and was still elevated on day 21 post-burn (1339.8 +/- 208.7 pg/ml) (mean +/- SEM, p < 0.01), when compared with healthy controls (82.2 +/- 10.8 pg/ml (mean +/- SEM)). Likewise, in trauma patients, serum VEGF showed a trend towards elevated values on the day of admission (186.9 +/- 43.9 pg/ml) and on day 3 after injury (193.2 +/- 62.1 pg/ml). Thereafter, serum VEGF increased further (day 7,507.0 +/- 114.7 pg/ml), peaked on day 14 (742.4 +/- 151.8 pg/ml) and was still elevated on day 21 after injury (693.1 +/- 218.6 pg/ml (mean +/- SEM, p < 0.01)). No significant correlation was observed between peak serum VEGF and initial severity of mechanical (Injury Severity Score) or burn injury (percentage of body surface burned). However, in both burn and trauma patients, the subgroup of patients with uncomplicated healing showed significantly higher increases of serum VEGF than the subgroup who developed severe complications during the post-traumatic course, such as sepsis, adult respiratory distress syndrome or multiple organ failure (p < 0.05). Thus, markedly enhanced levels of serum VEGF are present one to three weeks after trauma or burn injury. Further, occurrence of severe complications during the post-traumatic period is associated with lesser increases of serum VEGF.

SUMMARY One gram N-benzoyl-L-tyrosyl PABA was orally administered to 24 controls, 15 patients with chronic exocrine pancreatic disease, 13 patients after an attack of acute pancreatitis, two patients with gluten-sensitive enteropathy, and 10 patients with biliary tract disease, peptic ulcer, or other pathology of the gastrointestinal tract. In the presence of chymotrypsin, PABA is split from the peptide and excreted in the urine. The amount of PABA excreted serves as a parameter of exocrine pancreatic function. In 51 patients, exocrine pancreatic secretion was also assessed by the Lundh test. In the control group a mean of 59-6 12-2% (mean ± 2 SD) of the peptide-PABA was excreted over a period of six hours. PABA excretion in exocrine pancreatic deficiency was significantly less (p < 0.001) than in controls. (Fig. 1). In the small bowel, in the presence of chymotrypsin, the peptide is split resulting in the liberation of PABA, which is rapidly absorbed from the gut, undergoes conjugation in the liver, and is excreted in the urine. The amount of PABA recovered in the urine during a certain time is used as an index of exocrine pancreatic function. The test has been used for the assessment of exocrine pancreatic deficiency in protein deficient patas monkeys

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The oxidation of tetrahydropterins and 7,8-dihydropterins by ferric iron has been examined by both polarographic and spectral techniques. Quinonoid dihydropterin, an intermediate in the oxidation of the tetrahydropterins, is formed rapidly, as is ferrous iron. The quinonoid dihydropterin then rearranges to 7,8-dihydropterin. The rate of oxidation of 7,8-dihydropterins is much slower than that of tetrahydropterins. The reduction potential of the reversible quinonoid dihydropterin – tetrahydropterin couple has been measured and shown to be consistent with the known chemistry of these compounds. Kinetic measurements and structural studies have been used to formulate a mechanism for the oxidation of tetrahydropterins to quinonoid dihydropterins. This mechanism involves abstraction of an electron from position 5, followed by rapid loss of two protons and the other electron.

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