Knowledge of air‐water gas transfer velocities and water residence times is necessary to study the fate of mangrove derived carbon exported into surrounding estuaries and ultimately to determine carbon balances in mangrove ecosystems. For the first time, the 3He/SF6 dual tracer technique, which has been proven to be a powerful tool to determine gas transfer velocities in the ocean, is applied to Shark River, an estuary situated in the largest contiguous mangrove forest in North America. The mean gas transfer velocity was 3.3 ± 0.2 cm h−1 during the experiment, with a water residence time of 16.5 ± 2.0 days. We propose a gas exchange parameterization that takes into account the major sources of turbulence in the estuary (i.e., bottom generated shear and wind stress).

In Egypt, teas prepared from the fruits of Ammi visnaga L. (syn. “Khella”) are traditionally used by patients with urolithiasis. The aim of this study was to evaluate whether oral administration of an aqueous extract prepared from the fruits of Ammi visnaga as well as two major constituents khellin and visnagin could prevent crystal deposition in stone-forming rats. Hyperoxaluria was induced in male Sprague-Dawley rats by giving 0.75% ethylene glycol (EG) and 1% ammonium chloride (NH4Cl) via the drinking water. The Khella extract (KE; 125, 250 or 500 mg/kg) was orally administered for 14 days. The histopathological examination of the kidneys revealed that KE significantly reduced the incidence of calcium oxalate (CaOx) crystal deposition. In addition, KE significantly increased urinary excretion of citrate along with a decrease of oxalate excretion. Comparable to the extract, khellin and visnagin significantly reduced the incidence of calcium oxalate deposition in the kidneys. However, both compounds did not affect urinary citrate or oxalate excretion indicating a mechanism of action that differs from that of the extract. For KE, a reasonably good correlation was observed between the incidence of crystal deposition, the increase in citrate excretion and urine pH suggesting a mechanisms that may interfere with citrate reabsorption. In conclusion, our data suggest that KE and its compounds, khellin and visnagin, may be beneficial in the management of kidney stone disease caused by hyperoxaluria but that it is likely that different mechanism of action are involved in mediating these effects.

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Valeriana officinalis L. is a popular herbal treatment for mild sleep disorders. Clinical and non-clinical studies found contradictory results for valerian extracts and single constituents regarding the influence on sleep parameters. It was the aim of this study to investigate the sedative effects of a valerian root extract. Therefore, locomotor activity and core body temperature were recorded in male mice using radiotelemetry. A 70 % ethanolic extract prepared from the roots of V. officinalis (s. l.) and some of its single constituents, valerenic acid, linarin, and apigenin, were tested for effects on locomotion and body temperature over 180 minutes after oral administration. The extract was tested in a dose range of 250-1000 mg/kg, and only a dose of 1000 mg/kg valerian extract showed a mild short-term sedative effect with reduced locomotor activity between 66-78 min minutes after administration. Paradoxically, an increased activity was observed after 150 minutes after gavage. A dose of 1 mg/kg valerenic acid produced an intermittent stimulation of activity. However, a mild short-term sedative effect was found for linarin at 12 mg/kg and apigenin at 1.5 mg/kg. Considering the cumulative locomotor activity over the observation period of 180 min, it is concluded that neither the extract nor one of the compounds had considerable sedative effects. More precisely, the observed short-term changes in activity pattern indicate that valerian extract as well as the flavonoids linarin and apigenin are rather effective to reduce sleep latency than to act as a sleep-maintaining agent.

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