Ecologists have found a close relationship between the concentrations of nitrate (NO3-) and dissolved organic carbon (DOC) in ecosystems. However, it is difficult to determine the NO3- fate exactly because of the low coefficient in the constructed relationship. In the present paper, a negative power-function equation (r(2) = 0.87) was developed by using 411 NO3- data points and DOC:NO3- ratios ...

This work was supported by grants from the Fund for Scientific Research-Flanders (Belgium), the Research-fund of Ghent University and the Belgian Federation against Cancer, non profit organisation. F. S. is a Ph.D. student and K. V. B. is a post-doc., both supported by the Research-fund of Ghent University. V. D. C. and A. S. F. are research assistants of the Fund for Scientific Research-Flanders.

The role played by river networks in regional and global carbon (C) budgets is receiving increasing attention. Despite the potential of radiocarbon measurements (ΔC) to elucidate sources and cycling of different riverine C pools, there remain large regions for which no data are available and no comprehensive attempts to synthesize the available information and examine global patterns in the C c...

Over two hundred samples were collected in tropical headwater forested catchments in the lowland Amazon basin near Juruena, Mato Grosso Brazil. These were analyzed for fluorescence characteristics and DOC concentrations, and represented a range of terrestrial hydrologic flowpaths and firstorder streams during baseflow and stormflow conditions. The fluorescence index (FI) of McKnight et al. (200...

Brain metabolites and arterial acid-base measurements were made one hr after bilateral carotid artery occlusion in 2 different models of hypertensive rats. Animals used included renovascular hypertensive rats (RHR) with an altered renin-angiotensin system and desoxycorticosterone hypertensive rats (DHR) with low plasma renin activity (PRA). The mean value for supratentorial lactate of 7.41 mM/k...

The possible role of catecholamines in two forms of experimental hypertension in rats was investigated further. Inbred, spontaneously hypertensive (SH) Wistar rats had unchanged endogenous levels of norepinephrine (NE) in the three tissues studied, and a significantly (P<0.05) decreased rate of NE synthesis (C-tyrosine technique) in heart and brainstem but not in gut, in comparison to normotens...

Repeated administration of large doses of isoproterenol to rats produced myocardial enlargement and a fall in blood pressure. A defect in storage of norepinephrine (NE) was manifested by a decrease in endogenous NE, unimpaired uptake of H-NE, and an accelerated rate of loss of accumulated H-NE. This accelerated loss of H-NE was characterized by a more rapid disappearance of H-NE from the granul...

Inoculation of the CAM of the 10-day chick embryo with endotoxin preparations derived from the meningococcus and other Gram-negative microorganisms has been shown to result in multiple hemorrhages and death of the embryo within a few hours. Evidence has been presented to indicate that this lethal effect is specific for the general class of endotoxins derived from Gram-negative bacteria. Suscept...

Rabbits weighing from 2000 to 2500g were divided into the following groups: Group Ncontrol animals. Group D-animals with blood pressure elevated in metacorticoid hypertension elicited by the administration of desoxycorticosterone acetate and sodium chloride. Group Eanimals with blood pressure elevated by repeated doses of Ephedrinum basicum solutio oleosa (100mg/kg) every 2nd day during 2 weeks...