Six plant species were screened to determine potential suitability for phytoremediation of nitroglycerin (NG), a component in smokeless powders (SP). Seeds of Zea mays (corn), Triticum aestivum (wheat), Medicago sativa (alfalfa), Poa pratensis (Kentucky bluegrass), Trifolium pratense (red clover), and Phaseolus vulgaris (common bean) were sown into greenhouse mesocosms containing commercially prepared soil spiked with 0, 1, and 5% SP (w/w). Soil samples were collected 7, 60, and 90 days after seeding, extracted with ethanol, and analyzed for NG using a gas chromatograph with an electron capture detector. Plant growth observations were recorded using a simple scoring metric at 7, 14, 30, and 60 days after seeding. Soil nitrate and ammonium, potential by-products of NG decomposition, were quantified 90 days after seeding. NG disappearance in plant treatments was markedly, although not significantly (p > 0.05), higher than control at 1% SP, with legumes being the most successful treatment. Nitrate concentrations were significantly (p < 0.05) higher in legume than grass treatments. Soil ammonium was not correlated to any plant or SP treatment. Plant uptake of NG was minimal, suggesting a soil microbial effect in NG disappearance. More extensive screening studies are needed to determine which plants are the most successful remediators of NG. / Department of Natural Resources and Environmental Management

The primary functions of the cardiovascular system are to transport the required nutrients to sustain the metabolic activity of tissues and to remove the metabolic waste products from tissue. Therefore, a steady supply of oxygen for the cells is crucial. Vascular endothelium synthesizes both relaxing and contracting factors to regulate the local tissue blood flow. Nitric oxide (NO) is one of the major endothelium-derived relaxing factor. It is synthesized by endothelial nitric oxide synthase (eNOS), which interacts with soluble guanylyl cyclase in smooth muscle to produce cyclic guanosine monophosphate (cGMP) resulting in vascular relaxation. Nitroglycerin (GTN) is an organic nitrate used for the management of angina pectoris, hypertension and congestive heart failure, it is converted to NO or closely related moleculesin the vasculature resulting in vasodilatation. It has been demonstrated that chronic administration of GTN leads to nitrate tolerance, which is associated with increased arginase activity and reactive oxidative species (ROS)production. Supplement of L-arginine appears to reduce nitrate tolerance, however, the bioavailability of L-arginine is limited. It has been reported that L-citrulline supplement in human results in elevated plasma level of L-arginine. This study was designed to investigate the effect of long-term GTN treatment on the expressions and activities of arginase I, arginase II and eNOS, and on the production of cGMP inhuman umbilical vein endothelial cells (HUVECs).Moreover, the effect of L-citrulline on nitrate tolerance due to GTN treatment was examined. HUVECs were treated with GTN (10 µM), thrombin, L-arginine, L-citrulline and L-norvaline, alone or in combinations, for 1 hour (short-term treatment) or 24 hours(long-term treatment) followed by 30 minutes stimulation by GTN (100 µM).Western immunoblotting was used to measure the protein expression levelsof eNOS, arginase I and arginase II. Enzyme immunoassay and colorimetric assay were performed to determine the cGMP level and the arginase activities, respectively. Our results suggested that the amount of cGMP release in response to acute (30 minutes) GTN stimulation (100 µM)was reduced in HUVECs that were pre-treated with24 hour GTN(10 µM), and this is associated with an increased arginase activity. L-arginine,L-citrullineor L-norvaline alone was not able to prevent this reduction in cGMP release (nitrate tolerance), although L-arginine and L-norvaline, but not L-citrulline, prevented the increase in arginase activity. The combination of L-arginine or L-citrulline with L-norvaline is effective to protect HUVECs against nitrate tolerance. On the other hand, thrombin (a stimulator of eNOS, 1 U/ml) pre-treatment for 24 hours also reduced cGMP production toacute GTN stimulation. Similar to long-term GTN-induced nitrate tolerance, long-term thrombin-induced nitrate tolerance was not prevented by concomitant presence of L-arginine, L-citrulline or L-norvaline. Long-term thrombinpre-treatment also increased arginase activity and this effect was inhibited by L-arginine, L-citrulline and L-norvaline. The increased arginase activity by long-term GTN or thrombin pre-treatment was not associated with increased arginase protein expression. In conclusion, the present data suggested that prolonged pre-exposure to exogenous GTN or endogenous increase NO by thrombin induced nitrate tolerance in HUVECs, and this is unlikely the consequence of the increased arginase activity. In addition, neither L-arginine nor L-citrulline were effective in protecting HUVECs against nitrate tolerance, and only the combination of L-citrulline and L-norvaline or L-arginine and L-norvaline were effective. / published_or_final_version / Pharmacology and Pharmacy / Master / Master of Medical Sciences

Organic nitrates have been effective treatment for ischemic heart disease for over 100 years. However, there is limitation in their clinical utility since prolonged use of these drugs results in rapid development of nitrate tolerance, which is associated with increased arginase activity and production of reactive oxygen species. Quercetin, a flavonol abundantly found in fruits and vegetables, has been shown to reduce nitrate tolerance in vitro. The objective of this study is to investigate the potential effect of quercetin and three other flavonols (namely, kaempferol, myricetin and rutin) on the development of nitrate tolerance and the activity of arginase in endothelial cells. Human umbilical vein endothelial cells (HUVECs) were incubated with or without nitroglycerin (GTN) and/or flavonols followed by an acute stimulation with GTN. Level of cyclic guanosine monophosphate (cGMP) released into the cell medium was measured by an enzyme immunoassay. Activity of arginase in cell lysate was measured by a quantitative colorimetric arginase determination assay. Prior treatment with GTN at 〖10〗^(-5)M for either one or 24 hours did not affect the level of cGMP released from HUVECs induced by subsequent stimulation with GTN. On the other hand, arginase activity was significantly decreased in HUVECs pre-treated with GTN at 〖10〗^(-5)M alone for 24 hours and the decrease was not affected by the concomitant presence of the flavonols during the incubation period. However, the data obtained in HUVECs pre-treated with GTN for 24 hours is questionable due to the lack of a corresponding control (i.e. cells incubating with medium for 24 hours) for proper comparison. Pre-treatment for one hour with myricetin (〖10〗^(-5) M) and rutin (〖10〗^(-5) M), alone but not in combination with GTN (〖10〗^(-5) M), appears to increase the release of cGMP to subsequent stimulation by GTN (〖10〗^(-5) M). Rutin pre-treatment for one hour also seems to decrease the activity of arginase in HUVECs. However, these effects of myricetin and rutin were significant only when compared to the control group (without pre-treatment with GTN) but not when comparison was made to the vehicle-treated group, while there is no significant difference between the control and the vehicle group in both the cGMP release and arginase activity. As such, these potential effects of myricetin and rutin are inconclusive. The inability to induce nitrate tolerance in the present experimental condition does not allow further investigation on the potential effect of flavonols on nitrate tolerance. In addition, there are limitations in the present study [namely, lack of corresponding control for the 24 hour incubation groups and small sample size (n = 2-3)]. Therefore, the findings need to be interpreted with cautions; improvements of the present experimental design and increasing the number of experiments are needed in order to obtain more conclusive findings. Future experiments should also be performed in other vascular cells in addition to endothelial cells, as flavonols may exert their beneficial effect in an endothelium-independent manner. / published_or_final_version / Pharmacology and Pharmacy / Master / Master of Medical Sciences

Universiẗat, Diss., 1991--Freiburg (Breisgau).

No description available.

No description available.

No description available.

No description available.

Thesis (doctoral)--Christian-Albrechts-Universität zu Kiel, 1998.

Nitroglycerin (NG) is a toxic explosive commonly found in soil and contaminated groundwater at old manufacturing plants and military ranges. When NG enters an aquifer, it behaves as a dense non-aqueous phase liquid (DNAPL). Nitroglycerin is an impact sensitive explosive and therefore excavating the area to remove or treat the contaminant can be dangerous. In situ bioremediation and natural attenuation of NG have been proposed as remediation alternatives and it is therefore necessary to understand the degradation mechanisms of NG in contaminated soil and groundwater and investigate the potential for using bioremediation at contaminated sites. Many bacteria have been isolated for the ability to transform NG as a source of nitrogen, but no isolates have used NG as a sole source of carbon, nitrogen, and energy. We isolated Arthrobacter JBH1 from NG contaminated soil by selective enrichment with NG as the sole growth substrate. The degradation pathway involves a sequential denitration to 1,2-dinitroglycerin (DNG) and 1-mononitroglycerin (MNG) with simultaneous release of nitrite. Flavoproteins of the Old Yellow Enzyme (OYE) family capable of removing the first and second nitro groups from NG have been studied in the past and we identified an OYE homolog in JBH1 capable of selectively producing the 1 MNG intermediate. To our knowledge, there is no previous report on enzymes capable transforming MNG. Here we show evidence that a glycerol kinase homolog in JBH1 is capable of transforming 1 MNG into 1-nitro-3-phosphoglycerol, which could be later introduced into a widespread pathway, where the last nitro group is removed. Overall, NG is converted to CO2 and biomass and some of the nitrite released during denitration is incorporated into biomass as well. As a result, NG can be now considered a growth substrate, which changes the potential to bioremediate NG contaminated sites. The magnitude of the effect of biodegradation processes in the fate of NG in porous systems was unknown, and we have been able to quantify these effects, determine degradation rates, and have evidence that bioaugmentation with Arthrobacter sp. strain JBH1 could result in complete mineralization in contaminated soil and sediments contaminated with NG, without the addition of other carbon sources. Site specific conditions have the potential to affect NG degradation rates in situ. Experiments were conducted to investigate NG degradation at various pH values and NG concentrations, and the effects of common co-contaminants on NG degradation rates. Arthrobacter JBH1 was capable of growing on NG at pH values as low as 5.1 and NG concentrations as high as 1.2 mM. The presence of explosive co-contaminants at the site such as trinitrotoluene and 2,4-dinitrotoluene lowered NG degradation rates, and could potentially result in NG recalcitrance. Collectively, these results provide the basis for NG bioremediation and natural attenuation at sites contaminated with NG without the addition of other sources of carbon. Nonetheless, careful attention should be paid to site-specific conditions that can affect degradation rates.