The impact of saltwater intrusion on mercury cycling in coastal plain wetlands

Coastal wetlands are considered hotspots and the primary source of mercury (Hg) to adjacent waters. Because of the global sea level rise and hurricanes low-lying coastal areas are experiencing saltwater intrusion causing alteration in Hg biogeochemistry. However, limited studies have focused on saltwater effects on Hg in coastal wetlands. To explore potential salinity impact on Hg levels and bioaccumulation in food web, we collected water, sediment, and invertebrate samples for multiple times over two years along with in situ water quality measurements in the natural forest-marsh salinity gradient. Sampling sites consist of a freshwater wetland (FW; salinity < 0.5 ppt), partially degraded wetland (PDW; salinity < 5 ppt), and saltmarsh (SM; salinity < 18 ppt) and are located near Winyah Bay (South Carolina) and Albemarle - Pamlico Sound (North Carolina). We found that while elevated salinities ultimately reduced overall mercury levels by reducing dissolved organic carbon levels, dissolved oxygen and sulfate/chloride ratio are important determinants for methylmercury (MeHg) production in water column after the hurricanes in coastal wetlands of North Carolina. Similarly, mean sediment mercury levels were decreasing in the order of FW, PDW, and SM with increasing salinities in South Carolina. However, mean biota mercury levels did not show difference in FW and PDW but significantly lower in SM. Overall, we found a strong empirical evidence that salinity controls MeHg levels in sediment and its bioaccumulation in food web in coastal wetlands. My results suggest that increasing salinity levels can significantly reduce mercury levels in sediment and attenuate its accumulation in biota in coastal plain wetlands

The enigma of in vivo oxidative stress assessment: isoprostanes as an emerging target

Oxidative stress is believed to be one of the major factors behind several acute and chronic diseases, and may also be associated with ageing. Excess formation of free radicals in miscellaneous body environment may originate from endogenous response to cell injury, but also from exposure to a number of exogenous toxins. When the antioxidant defence system is overwhelmed, this leads to cell damage. However, the measurement of free radicals or their endproducts is tricky, since these compounds are reactive and short lived, and have diverse characteristics. Specific evidence for the involvement of free radicals in pathological situations has been difficult to obtain, partly owing to shortcomings in earlier described methods for the measurement of oxidative stress. Isoprostanes, which are prostaglandin-like bioactive compounds synthesized in vivo from oxidation of arachidonic acid, independently of cyclooxygenases, are involved in many human diseases, and their measurement therefore offers a way to assess oxidative stress. Elevated levels of F2-isoprostanes have also been seen in the normal human pregnancy, but their physiological role has not yet been defined. Large amounts of bioactive F2-isoprostanes are excreted in the urine in normal basal situations, with a wide interindividual variation. Their exact role in the regulation of normal physiological functions, however, needs to be explored further. Current understanding suggests that measurement of F2-isoprostanes in body fluids provides a reliable analytical tool to study oxidative stress-related diseases and experimental inflammatory conditions, and also in the evaluation of various dietary antioxidants, as well as drugs with radical-scavenging properties. However, assessment of isoprostanes in plasma or urine does not necessarily reflect any specific tissue damage, nor does it provide information on the oxidation of lipids other than arachidonic acid

Reduction of the infarcted area with the use of simplified coronary sinus retroperfusion during experimental coronary artery occlusion

This study examined if the use of simplified coronary sinus retroperfusion would lead to any reduction in the infarcted area associated with improved right and left ventricular function. Twelve mongrel dogs were entered in this study. Following anesthesia, a fast response thermistor was placed on the pulmonary artery via the jugular vein and aorta via the left ventricular apex. The left anterior descending artery (LAD) was separated from the vein, A retrograde cardioplegia catheter was inserted into the coronary sinus. Following these procedures, LAD was occluded for a period of 3.5 h. After 30 min ischemia, the aorta-coronary sinus connection was established. The animals were divided into two equal groups. One group was not treated and was considered the control group (six animals). In the remaining group (six animals), retroperfusion was used and was considered the retroperfusion group. At the end of the study, the left ventricular ejection fraction was 65+/-15% in the retroperfusion group and 48+/-5% in the control group (P < 0.05). The left ventricular stroke work index was 0.44+/-0.04 (g m/kg) in the retroperfusion group and 0.31+/-0.05 (g m/kg) in the control group (P < 0.05). Cardiac output was 1650+/-75 ml/min in the retroperfusion group and 1250+/-125 ml/min in the control group. The ratio of the infarct size to the area at risk was 49+/-5% in the control group and 7+/-3% in the retroperfusion group. In light of these studies, we conclude that simplified coronary sinus retroperfusion appears to be an effective method that must be taken into consideration. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved

Effect of resveratrol on nitrate tolerance in isolated human internal mammary artery

The present Study aims to examine whether resveratrol, a natural antioxidant present in red wine, restores the tolerance to nitroglycerin (GTN) on isolated human internal mammary artery (IMA), using an in vitro model of nitrate tolerance. IMA rings were obtained from 53 male patients undergoing coronary bypass operation. Nitrate tolerance was induced by incubating the artery ring with 100 mu M GTN for 90 minutes. Concentration-response curves to GTN (10(-9) to 10(-4) M) were obtained on IMA rings precontracted with noradrenaline. A low concentration (5 mu M) Of lucigenin was used as a tool to measure superoxide production in IMA segments. GTN produced concentration-dependent relaxation in isolated human IMA rings. Preexposure of artery rings to GTN reduced the relaxations to GTN [E-max values: 105 +/- 2%, and 76 +/- 3%, n = 10 to 12, P < 0.05; EC50 values (-log M): 6.72 +/- 0.05 and 4.95 +/- 0.06, P < 0.05, respectively]. Relaxation to sodium nitroprusside remained unchanged. Diminished relaxation to GTN is partially restored after removing endothelium or L-G-nitro-L-arginine (L-NOARG, 10-4 M) or superoxide dismutase (20 and 200 U/mL) or catalase (200 U/mL) pretreatments. Pretreatments with resveratrol (1, 10, and 20 mu M) for 20 minutes relatively improved the reduced relaxation to GTN in tolerant IMA rings. Coadministration of L-NOARG with resveratrol did not abolish the beneficial effect of resveratrol on nitrate tolerance. The inhibitory effect of resveratrol on GTN-induced tolerance was not abolished in arterial rings without endothelium. Exposure to GTN increased superoxide production in IMA segments with endothelium. Endothelium denudation, L-NOARG, or Superoxide dismutase pretreatments markedly inhibited the increased Superoxide production in tolerant arteries. Resveratrol (1 and 10 mu M) almost completely abolished basal or NAD(P)H-stimulated superoxide production in tolerant and nontolerant arteries. Vascular tolerance to GTN, in in vitro tolerant human IMA rings, can be induced by endothelial superoxide anions. Resveratrol partially restored the reduced relaxation to GTN by inhibiting NAD(P)-derived superoxide production in endothelium

The effect of CYP1A1 and GSTP1 isozymes on the occurrence of aortic aneurysms.

BACKGROUND: Aortic aneurysms are vascular diseases that are associated with high mortality and morbidity. Cytochrome P450 CYP1A1 and glutathione S-transferase (GSTP1) isozymes were searched and compared with the patients who had experienced aortic surgery due to aortic aneurysm and atherosclerotic patients without aneurysm to find the relation of the oxidative stress with the aneurysms. MATERIALS AND METHODS: Study group consisted of the patients with the diagnosis of aortic aneurysm (group I, n: 12) and control group who were operated for coronary bypass surgery: preoperatively drug users (group II, n: 21) and nonusers (group III, n: 15). Paraffin sections (4 μm thick) of aortic biopsy materials were stained with hematoxylin and eosine, CYP1A1 and GSTP1 immunohistochemical markers. The specimens were evaluated using light microscopy at 40- to 400-fold magnification. RESULTS: The expressions of CYP1A1 and GSTP1 isozymes were found statistically significantly higher in the patients who have an aortic aneurysm than both the control groups (p 0.05). CONCLUSIONS: In this pioneering study, CYP1A1 and GSTP1 isozymes are related with the aneurysms. The strategy that prevents the oxidative stress for the patients who had aortic aneurysms could be a valuable choice of searching to effect the aneurysmal progression

Aneurysms

Background Aortic aneurysms are vascular diseases that are associated with high mortality and morbidity. Cytochrome P450 CYP1A1 and glutathione S-transferase (GSTP1) isozymes were searched and compared with the patients who had experienced aortic surgery due to aortic aneurysm and atherosclerotic patients without aneurysm to find the relation of the oxidative stress with the aneurysms.Materials and Methods Study group consisted of the patients with the diagnosis of aortic aneurysm (group I, n: 12) and control group who were operated for coronary bypass surgery: preoperatively drug users (group II, n: 21) and nonusers (group Ill, n: 15). Paraffin sections (4 pm thick) of aortic biopsy materials were stained with hematoxylin and eosine, CYP1A1 and GSTP1 immunohistochemical markers. The specimens were evaluated using light microscopy at 40- to 400-fold magnification.Results The expressions of CYP1A1 and GSTP1 isozymes were found statistically significantly higher in the patients who have an aortic aneurysm than both the control groups (p 0.05).Conclusions In this pioneering study, CYP1A1 and GSTP1 isozymes are related with the aneurysms. The strategy that prevents the oxidative stress for the patients who had aortic aneurysms could be a valuable choice of searching to effect the aneurysmal progression

Cardiac valve replacement with mechanical prostheses in patients aged 65 years and over

Background and aim of the study: Recent data regarding the performance of mechanical prostheses in patients aged greater than or equal to65 years are scant. Hence, the outcome of mechanical prosthesis implantation in this age group has been retrospectively evaluated