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BackgroundATP binding is essential for the bioactivity of several growth factors including nerve growth factor, fibroblast growth factor-2 and brain-derived neurotrophic factor. Vascular endothelial growth factor isoform 165 (VEGF-A165) induces the proliferation of human umbilical vein endothelial cells, however a dependence on ATP-binding is currently unknown. The aim of the present study was to determine if ATP binding is essential for the bioactivity of VEGF-A165.ResultsWe found evidence that ATP binding toVEGF-A165 induced a conformational change in the secondary structure of the growth factor. This binding appears to be significant at the biological level, as we found evidence that nanomolar levels of ATP (4-8 nm) are required for the VEGF-A165-induced proliferation of human umbilical vein endothelial cells. At these levels, purinergic signaling by ATP via P2 receptors can be excluded. Addition of alkaline phosphate to cell culture lowered the ATP concentration in the cell culture medium to 1.8 nM and inhibited cell proliferation.ConclusionsWe propose that proliferation of endothelial cells is induced by a VEGF-A165-ATP complex, rather than VEGF-A165 alone.

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The simplified oscillation method was adapted to register nasal resistance because complicated and difficult procedures limited other known rhinomanometric tests. An initial study of thirty-nine subjects compared the elTect of different-sized masks, revealing that the smaller the face mask, the smaller the capacitance and the higher the effective resistance. After an initial measurement, a second study group of twenty healthy and twenty pollinosis patients aged from 4 to 40 years underwent nasal provocation with grass pollen extract. Both study groups showed that despite high resistance, reactances were minor. This occurs because the nose acts as an aperture and an aperture has minimal reactances. With increasing concentrations of pollen extract, the nasal resistance of poltinosis subjects increased steadily, whereas the controls showed no change. Passive anterior rhinomanometry was measured for comparison and results contrasted sharply with the oscillation method: prior to provocation, initial values of control and pollinosis groups were already significantly different; after provocation, there was a statistically significant rise in resistance amongst the control as well as the pollinosis subjects. Further, the oscillation method for measuring nasal resistance proved to be simple, effective, and suitable for children.Correspondence; Dr B. Huber. Universitats-Kinderklinik, Adenauer Allee 119. 5300 Bonn 1. West Germany.O009-9O90/8i/07GO-0385$02.OO © '981 Blackwell Scientific Publications 385[1) /oF ig. 2. Oscillation method theory and its equivalent electrical circuit. Zo. Reference impedance; K, oscillating flow produced by a piston pump: P. alternating pressure; Z*, respiratory tract impedance. For derivation of formulae see Eranetzki et al. (1979). Fig. 3. Phase diagram. The respiratory impedance Z, expressed by its resistance R^ (mbar/l/see) and by its phase angle 0 can be read from the curved co-ordinates. Phase angle