[1] In this paper we present results of a global gravity field recovery using half a year of CHAMP data. We use the energy integral of the motion of a satellite to transform satellite velocities into values of gravitational potential. The feasibility of this approach has already been demonstrated by several groups, using CHAMP reduced-dynamic orbits. We show, that the potential recovered from this kind of orbits depends on the a priori gravity field used for orbit determination. Thus, it cannot be excluded that errors present in the prior field propagate into the new CHAMP gravity model. It is the intention of this paper to avoid this dependency through the use of kinematic orbits, which are free from prior information. The derived potential model, TUM-1S, is validated by comparison to ground data and by satellite orbit residuals. It is shown to be comparable in quality to other state-of-the-art gravity field models.

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The wet weight of the stomach, small intestine, caecum, and colon were significantly reduced (p<0O001) in intravenously fed rats compared with orally fed controls. Human epidermal growth factor (urogastrone) reversed this atrophy. Detailed analysis of the small intestine showed a similar effect on intestinal crypt cell population, mitoses per crypt, and protein content. Brush border y glutamyltransferase and a glucosidase activities were reduced by up to 50% throughout the small intestine of the animals fed intravenously. The specific activities (mU/mg protein) were unchanged, as a concomitant decrease in the tissue weight and protein content also occurred. Intestinal brush border enzyme activities in the rats treated with urogastrone-epidermal growth factor were restored to those seen in the orally fed rats except for a glucosidase activity in the proximal gut. In addition, the specific activity of y glutamyltransferase was highly significantly increased (p<001) in all regions of the small intestine. Thus, although urogastrone administration prevents the decrease in brush border enzyme activity seen after the removal of luminal nutrition, the response seems to differ depending on the intestinal location, with the specific activities of some enzymes being higher than those seen in orally fed rats. Urogastrone-epidermal growth factor can thus significantly increase the functional ability of the intestine in addition to its trophic effects. While many aspects of the molecular biology of epidermal growth factor are now well understood,' its role in vivo is still uncertain. It stimulates the proliferation and maturation of the neonatal intestine,2A the functional maturity of the preweaning intestine,' and the maturation of brush border enzymes in the neonate.67 Recent studies have also shown human epidermal growth factor, or urogastrone, to be a potent stimulator of intestinal epithelial cell proliferation in adult animals" and in humans."' This proliferative effect is dependent on the induction of polyamine synthesis." The effect of epidermal growth factor on intestinal function, however, remains unclear. The aim of this study was to (i) investigate the effects of urogastrone-epidermal growth factor on the activity of two intestinal brush border enzymes in adult rats and (ii) to determine whether the changes in enzyme activities were related to variations in proliferative activity. Methods EXPERIMENTAL PLANThree groups of 12 rats (male, 230-240 g Wistar strain) (Olac, Blackthorn, Oxon) were used. The first group was fed on a standard pelleted diet (Labshure PRD), the second on an intravenous diet which was intended to be isocaloric,89 and the third was given the intravenous diet and urogastrone-epidermal growth factor (60 tg/ratI day). The rats were maintained on the appropriate diet for eight days. The urogastrone was recombinant urogastrone and had the same amino acid sequence and biological activity as natural epidermal growth factor. 12 INTRAVENOUS NUTRITIONRats were anaesthetised with intramuscular fen...

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