Levels Of NO3 Research Articles

A survey of nitrate and nitrite concentrations in conventional and organic-labeled raw vegetables at retail.

A national survey of the nitrate ( NO3(-)) and nitrite ( NO2(-)) concentrations in raw and highly consumed vegetables available at retail in the United States was conducted. A total of 194 samples of fresh broccoli, cabbage, celery, lettuce, and spinach categorized as conventional or organic by label were collected from 5 major cities in different geographic regions of the United States and analyzed to determine NO3(-) and NO2(-) concentrations. There were no differences in the mean NO2(-) values of conventional compared with organic vegetables taken from the 5 metropolitan areas. However, significant differences in mean pairwise comparisons between some conventional and organic vegetables for NO3(-) content were observed. The mean NO2(-) concentration of both conventional and organic vegetables ranged between 0.1 and 1.2 mg/kg of fresh weight (FW) with the exception of conventional spinach that contained 8.0 mg/kg FW. Mean NO3(-) contents of conventional broccoli, cabbage, celery, lettuce, and spinach were 394, 418, 1496, 851, and 2797 mg/kg FW, respectively, while their organic-labeled counterparts averaged 204, 552, 912, 844, and 1318 mg/kg FW. In most cases, organic vegetables were numerically lower in NO3(-) content than their conventional counterparts. Based on survey results, the finding that low NO3(-) levels were observed in some organic vegetables in different cities may warrant further study to determine if true differences exist, due to production practices, seasonal differences, and the magnitudes of those differences. Furthermore, the geographic differences in NO3(-) content of vegetables may flaw estimates of daily NO2(-) and NO3(-) exposure.

Predominant populations of indigenous soybean-nodulating Bradyrhizobium japonicum strains obtained from organic farming systems in Minnesota.

Bradyrhizobium from organic fields in Minnesota were isolated and genotyped to assess diversity of soybean-bradyrhizobia in organic farming systems that can be used to improve soybean productivity. Soil samples were collected from 25 organic fields in Minnesota during May to July 2012. Soybean (cv. Lambert) was used as a host to trap indigenous bradyrhizobia in each sample. Genetic diversity of Bradyrhizobium strains (n=733) was determined using the horizontal, fluorophore-enhanced, repetitive extragenic palindromic-PCR (HFERP) DNA fingerprinting technique and the soybean-bradyrhizobia were classified into 79 different genotypes. Of these, 15 dominant genotypes were found and were highly similar (>92% fingerprint similarity) to serotypes USDA 127 (40.4%), USDA 4 (31.8%) and USDA 123 (15.5%), which were the three main populations of soybean-bradyrhizobia in organic fields. Bradyrhizobium japonicum serogroup USDA 4 strains were found to make up a previously unrecognized, predominant rhizobial population in the organic farming soils examined. The relative abundance of strain USDA 4 was negatively correlated with that of USDA 127 and this relationship may be influenced by the levels of NO3 -N and other soil edaphic factors. The local community of bradyrhizobia can be affected by applying inoculant bacteria to organic fields. Based on these results, soybean production in organic farms may be improved by displacing strains similar to USDA 4 with those better at nitrogen fixation and competitive ability than indigenous strains.

Effects of seasonal change and seawater intrusion on water quality for drinking and irrigation purposes, in coastal aquifers of Dar es Salaam, Tanzania

Groundwater is the major source to meet domestic, industrial and agricultural needs in the city of Dar es Salaam, Tanzania. However, population growth, increasing urbanization, industrialization and tourism, and climatic changes have caused an intensive exploitation of groundwater resources leading the aquifers become more vulnerable to seawater intrusion. The aim of this study is to examine the variations of groundwater chemistry (as resulting from natural and anthropogenic inputs) depending on seasonal changes, in order to evaluate water quality for drinking and irrigation purposes. Physical and chemical data come from the analysis of groundwater samples, collected from 72 wells, used for the evaluation of water quality parameters, during a year of monitoring. Pattern diagrams, geochemical modeling techniques and Principal Component Analysis (PCA) have been used to identify the main factors influencing groundwater composition. Based on the hydrochemistry, the groundwater was classified into three types: (a) Na–Cl, (b) Ca–Cl, (c) mixed Ca–Na–HCO3–Cl (d) mixed Ca–Mg–Cl–SO4. The geochemical modeling results show that groundwater chemistry is mainly influenced by evaporation process, as it is suggested by the increase of Na and Cl ions concentrations. According to irrigation water quality assessment diagrams of USDA, most water samples from dry and rainy seasons, distributed in category C2–S1, C3–S1, C3–S2, C4–S2 highlighting medium to very high salinity hazard and low to medium sodium content class. PCA evidenced the role of seawater intrusion, evaporation process and anthropogenic pollution (i.e. high NO3 levels due to agricultural activities), as the major factors that influenced the water chemistry, and hence the water quality. Based on Pearson correlation matrix, the presence of high correlations (>0.8) among Na, Cl, Mg and SO4, in association with EC, were interpreted as the seawater intrusion effects. In this area groundwater quality is generally low, and often exceeds permissible limits of standard guideline values of WHO and FAO, referred to EC and chloride values. The high salinity and the groundwater level depletion create serious problems for current use of water supplies as well as future exploitation.

Variability of mineral nitrogen contents in soil as affected by meat and bone meal used as fertilizer

In recent years, a number of alternative sources of organic matter have been discovered, such as producis made of waste materials and recycled into composts or as meal of meat and bone. Meat and bone meal, a by-product of the meat industry, is rich in N and P and hence it can be a viable alternative to mineral fertilizers. This study determined the direct effect of different doses of meat and bone meal (MBM) used as fertilizer on the content of mineral N in soil. The effect of MBM fertilizer applied at rates of 1.0, 1.5, 2.0, and 2.5 t ha-1 was compared with no fertilization. The experiment was conducted in the years 2007-2009 at the research station in Balcyny, Poland. MBM was applied every year for 3 yr, with the following crop sequence: 2007 winter wheat (T. aestivum), 2008 winter rape (Brassica rapa L. subsp. oleifera (DC.) Metzg.), and 2009 spring wheat. Determination of mineral N (NO3--N and NH4+-N) were taken from the 0-30 cm layer, each year, during the full plant vegetation. The study found that changes in the mineral N content in soil depended on the dose of MBM and the crop species in a sequence. Each 0.5 t of MBM above 1.0 t ha-1 increased the mineral N content by an average of 4 mg. MBM applied every year at 2.0 and 2.5 t ha-1 produced a 2.33- and 2.56-fold increase in the mineral N content compared to unfertilized soil. The rate of release of NO3--N was found to be the highest at those sites in all the years of study, while that of NH4+-N was highest during the first 2 yr of study. The levels of NO3--N lay within the range of very low fertility. A strong correlation was found between NO3--N and NH4+-N content in soil and the N content in winter and spring wheat (Triticum aestivum L.) grain and in winter rapeseed (Brassica rapa L. subsp. oleifera (DC.) Metzg.) The NO3--N and NH4+-N compounds released from MBM were a good source of N for the plants.

Anthocyanins suppress the secretion of proinflammatory mediators and oxidative stress, and restore ion pump activities in demyelination

The aim of this study was to investigate the protective effect of anthocyanins (ANT) on oxidative and inflammatory parameters, as well as ion pump activities, in the pons of rats experimentally demyelinated with ethidium bromide (EB). Rats were divided in six groups: control, ANT 30 mg/kg, ANT 100 mg/kg, EB (0.1%), EB plus ANT 30 mg/kg and EB plus ANT 100 mg/kg. The EB cistern pons injection occurred on the first day. On day 7, there was a peak in the demyelination. During the 7 days, the animals were treated once per day with vehicle or ANT. It was observed that demyelination reduced Na+,K+-ATPase and Ca2+-ATPase activities and increased 4-hydroxynonenal, malondialdehyde, protein carbonyl and NO2plus NO3 levels. In addition, a depletion of glutathione reduced level/nonprotein thiol content and a decrease in superoxide dismutase activity were also seen. The dose of 100 mg/kg showed a better dose–response to the protective effects. The demyelination did not affect the neuronal viability but did increase the inflammatory infiltrate (myeloperoxidase activity) followed by an elevation in interleukin (IL)-1β, IL-6, tumor necrosis factor-α and interferon-γ levels. ANT promoted a reduction in cellular infiltration and proinflammatory mediators. Furthermore, ANT restored the levels of IL-10. Luxol fast blue staining confirmed the loss of myelin in the EB group and the protective effect of ANT 100 mg/kg. In conclusion, this study was the first to show that ANT are able to restore ion pump activities and protect cellular components against the inflammatory and oxidative damages induced by demyelination.

Benefit Agmatine Effects in Experimental Multiple Sclerosis. CNS Nitrosative and Oxidative Stress Suppression / Protektivni Efekti Agmatina U Eksperimentalnoj Multiploj Sklerozi. Supresija Nitrozativnog I Oksidativnog Stresa U CNS-U

Summary The aim of this study was to investigate the exogenous agmatine influence on nitrosative and oxidative stress parameters in acute phase of multiple sclerosis (MS) experimental model, experimental autoimmune encephalomyelitis (EAE). EAE was induced by subcutaneous injection of myelin basic protein (50 μg per animal). Sprague-Dawley rats were divided into five groups: I group - (CG), treated by PBS (i.p.), II group - (EAE), III group - (CFA), treated with Complete Freund’s adjuvant (0.2 ml subcutaneously), IV group - (EAE+AGM), treated by agmatine (75 mg/kg bw i.p.) upon EAE induction and V group - (AGM), received only agmatine in the same dose. The animals were treated every day during experiment - from day 0 to 15, and clinically scored every day. They were sacrificed on day 16 from MBP application. NO2+NO3, S-nitrosothiols (RSNO), malondyaldehide (MDA) and reduced glutathione (GSH) concentrations and superoxide dismutase (SOD) activity were determined in rat whole encephalitic mass (WEM) and cerebellum homogenates. Agmatine exerted strong protective effects on EAE clinical symptoms (p<0.05). In EAE brain homogenates, NO2+NO3, RSNO and MDA concentrations were increased compared to CG values. Agmatine treatment diminished NO2+NO3, RSNO and MDA levels in EAE animals (p<0.05). In EAE rats, GSH level and SOD activity were decreased compared to CG values, but agmatine treatment increased both parameters compared to EAE untreated animals (p<0.05). Immunohistochemical staining supported the clinical and biochemical findings in all groups. The CNS changes in EAE are successfully supressed by agmatine application, which could be the the new aspect of the neuroprotective effects of agmatine.

Water Quality Assessment and Nitrogen Pollution Sources Analysis of the West Lake, Hangzhou, China

Single factor water quality identification index (SFWQII) and Comprehensive water quality identification index (CWQII) were applied to the data of 6 parameters for water quality of West Lake at 10 different sites and 4 main inflows in the West Lake basin, generated during March 2012 to February 2013. This study evaluated and elucidated the temporal and spatial variation of each parameter on water quality and the main pollution factor of West Lake by SFQII. CWQII based on the SFQII was applied to evaluate the eutrophication level of West Lake and substantiated mesotrophic waters. Stable isotopes of nitrate were used to identify the nitrate sources of West Lake. The δ15NNO3 values in samples from the West Lake and inflows had a range of 2.6‰ to 12.0‰, while the δ15NNO3 values in Qiantang River was 5.3‰, in rainfall was 5.2‰ and in runoff was 3.6‰, respectively. Animal wastes, commercial fertilizer and domestic sewage were the main nitrate sources. The groundwater and denitrification might increase the levels of NO3- in West Lake.

Nitrate source identification in the Baltic Sea using its isotopic ratios in combination with a Bayesian isotope mixing model

Abstract. Nitrate (NO3−) is the major nutrient responsible for coastal eutrophication worldwide and its production is related to intensive food production and fossil-fuel combustion. In the Baltic Sea NO3− inputs have increased 4-fold over recent decades and now remain constantly high. NO3− source identification is therefore an important consideration in environmental management strategies. In this study focusing on the Baltic Sea, we used a method to estimate the proportional contributions of NO3− from atmospheric deposition, N2 fixation, and runoff from pristine soils as well as from agricultural land. Our approach combines data on the dual isotopes of NO3− (δ15N-NO3− and δ18O-NO3−) in winter surface waters with a Bayesian isotope mixing model (Stable Isotope Analysis in R, SIAR). Based on data gathered from 47 sampling locations over the entire Baltic Sea, the majority of the NO3− in the southern Baltic was shown to derive from runoff from agricultural land (33–100%), whereas in the northern Baltic, i.e. the Gulf of Bothnia, NO3− originates from nitrification in pristine soils (34–100%). Atmospheric deposition accounts for only a small percentage of NO3− levels in the Baltic Sea, except for contributions from northern rivers, where the levels of atmospheric NO3− are higher. An additional important source in the central Baltic Sea is N2 fixation by diazotrophs, which contributes 49–65% of the overall NO3− pool at this site. The results obtained with this method are in good agreement with source estimates based upon δ15N values in sediments and a three-dimensional ecosystem model, ERGOM. We suggest that this approach can be easily modified to determine NO3− sources in other marginal seas or larger near-coastal areas where NO3− is abundant in winter surface waters when fractionation processes are minor.

Levels of reactive nitrogen in surface and ground water samples obtained from different parts of Bangladesh

A total of 114 water samples collected from different parts of Bangladesh were analyzed for the level of reactive nitrogen species NO3 and NH3. Nitrate was determined in 20 surface water, 28 motorized deep tube well and 66 hand operated tube well samples. Ammonia was determined in 18 surface water, 14 deep tube well and 49 hand operated tube well samples. These sites were randomly selected. Nitrate levels were found to be generally low (below 3 mg/l) in 112 of the 114 samples tested, which is much below permissible level of 10 mg/l of drinking water in Bangladesh. Ammonia concentration was, however, found to be about 4 mg/l in majority of the samples tested which is higher than maximum permissible limit of 0.5 mg/l in drinking water. Possible reasons for low level of nitrate and relatively high level of ammonia in surface and ground water samples in Bangladesh is discussed DOI: http://dx.doi.org/10.3329/jbas.v38i1.20214 Journal of Bangladesh Academy of Sciences, Vol. 38, No. 1, 75-82, 2014

Signal interactions in the regulation of root nitrate uptake.

In most aerobic soils, nitrate (NO3(-)) is the main nitrogen source for plants and is often limiting for plant growth and development. To adapt to a changing environment, plants have developed complex regulatory mechanisms that involve short and long-range signalling pathways in response to both NO3(-) availability in the soil and other physiological processes like growth or nitrogen (N) and carbon (C) metabolisms. Over the past decade, transcriptomic approaches largely contributed to the identification of molecular elements involved in these regulatory mechanisms, especially at the level of root NO3(-)uptake. Most strikingly, the data obtained revealed the high level of interaction between N and both hormone and C signalling pathways, suggesting a strong dependence on growth, development, and C metabolism to adapt root NO3(-) uptake to both external NO3(-) availability and the N status of the plant. However, the signalling mechanisms involved in the cross-talk between N, C, and hormones for the regulation of root NO3(-) uptake remain largely obscure. The aim of this review is to discuss the recent advances concerning the regulatory pathways controlling NO3(-) uptake in response to N signalling, hormones, and C in the model plant Arabidopsis thaliana. Then, to further characterize the level of interaction between these signalling pathways we built on publicly available transcriptome data to determine how hormones and C treatments modify the gene network connecting root NO3(-) transporters and their regulators.

Nitric oxide donors rescue diabetic nephropathy through oxidative-stress-and nitrosative-stress-mediated Wnt signaling pathways.

Aims/IntroductionThe role of the renal nitric oxide (NO) system in the pathophysiology of diabetic nephropathy constitutes a very challenging and fertile field for future investigation. The purpose of the present study was to investigate whether NO donors can attenuate diabetic renal fibrosis and apoptosis through modulating oxidative-and nitrosative-stress, and Wnt signaling using in vivo diabetic models.Materials and MethodsDiabetic rat was induced by a single intraperitoneal injection of streptozotocin. Rats in each group were intraperitoneally given 2,2′-(hydroxynitrosohydrazino)bis-ethanamine (1 U/kg/day) and vehicle for 28 and 56 consecutive days. Expression of the oxidative-and nitrosative-stress, and Wnt signaling components were examined in kidneys from diabetic animals by quantitative reverse transcription polymerase chain reaction, western blot analysis and immunohistochemical staining.ResultsNO donor treatment significantly reduced the ratio of kidney weight to bodyweight and proteinuria. This treatment also significantly restored the suppressive effect of diabetes on urinary NO2 + NO3 levels. Immunohistochemistry showed that NO donor treatment significantly reduced transforming growth factor (TGF)-β1, fibronectin, cleaved caspase-3 and triphosphate-biotin nick end-labeling expression in the glomeruli of diabetic rats. We found that diabetes promoted 8-hydroxy-2′-deoxyguanosine, and peroxynitrite expression coincided with reduced endothelial NO synthase expression in glomeruli. Interestingly, NO donor treatment completely removed oxidative stress and nitrosative stress, and restored endothelial NO synthase expression in diabetic renal glomeruli. Immunohistomorphometry results showed that NO donor treatment significantly restored suppressed Wnt5a expression and β-catenin immunoreactivities in glomeruli. Based on laser-captured microdissection for quantitative reverse transcription polymerase chain reaction, diabetes significantly increased TGF-β1, and fibronectin expression coincided with depressed Wnt5a expression. NO donor treatment reduced TGF-β1, fibronectin activation, and the suppressing effect of diabetes on Wnt5a and β-catenin expression in renal glomeruli.ConclusionsNO donor treatment alleviates extracellular matrix accumulation and apoptosis in diabetic nephropathy in vivo by not only preventing the diabetes-mediated oxidative and nitrostative stress, but also restoring downregulation of endothelial NO synthase expression and Wnt/β-catenin signaling. These findings suggest that modulation of NO is a viable alternative strategy for rescuing diabetic renal injury.

Major – but rare – spring blooms in 2014 in San Francisco Bay Delta, California, a result of the long-term drought, increased residence time, and altered nutrient loads and forms

Rare spring blooms, >20μgl−1 chlorophyll a, were observed in the San Francisco Bay Delta during the drought year of 2014 in both the upper Sacramento River and in Suisun Bay. The upper Sacramento River bloom was dominated by chlorophytes, but biomass and photosynthetic efficiency (based on variable fluorescence, Fv/Fm) precipitously declined downstream when cells were exposed to sewage effluent and NH4+ levels>70μM-N. Further downriver, substantial rates of nitrification occurred, based on increasing levels of NO3− and NO2− in proportion to decreasing NH4+ concentrations, reducing NH4+ levels to <10μM-N. The other major tributary, the San Joaquin River, had extremely high nutrient levels (NO3−>400μM-N, PO43−>13μM-P, but NH4+~2μM-N), very low chlorophyll a levels (~3μgL−1) and low Fv/Fm values, but elevated bacterial production, suggesting presence of an algal inhibitor, possibly an herbicide. Both rivers converge above Suisun Bay, where elevated NO3− (>50μM-N), sufficient PO43− (>3μM-P), and reduced NH4+ levels (as low as 6μM-N), and reduced flow created conditions conducive to a spatially large and physiologically healthy (elevated Fv/Fm) diatom bloom dominated by the species Entomoneis sp. We conceptualize this bloom as a “window of opportunity” response by these diatoms to multiple factors promoted by the drought, including longer residence time for cell growth and biomass accumulation, and longer time for in-river nitrification to occur, reducing sewage-derived NH4+ to a level where diatoms could access NO3− for uptake and growth. We suggest that management practices that favor higher rates of flow may narrow the “window of opportunity” for phytoplankton growth, potentially leading to low productivity and food limitation for fish. Under high flow, a condition of “washout” may develop where both chlorophyll and unassimilated nutrients are transported out of the bay, and the phytoplankton that do develop are less favorable in terms of community composition for supporting the upper food web.

Full-dimensional diabatic potential energy surfaces including dissociation: The 2E″ state of NO3

A scheme to produce accurate full-dimensional coupled diabatic potential energy surfaces including dissociative regions and suitable for dynamical calculations is proposed. The scheme is successfully applied to model the two-sheeted surface of the (2)E″ state of the NO3 radical. An accurate potential energy surface for the NO₃⁻ anion ground state is developed as well. Both surfaces are based on high-level ab initio calculations. The model consists of a diabatic potential matrix, which is expanded to higher order in terms of symmetry polynomials of symmetry coordinates. The choice of coordinates is key for the accuracy of the obtained potential energy surfaces and is discussed in detail. A second central aspect is the generation of reference data to fit the expansion coefficients of the model for which a stochastic approach is proposed. A third ingredient is a new and simple scheme to handle problematic regions of the potential energy surfaces, resulting from the massive undersampling by the reference data unavoidable for high-dimensional problems. The final analytical diabatic surfaces are used to compute the lowest vibrational levels of NO₃⁻ and the photo-electron detachment spectrum of NO₃⁻ leading to the neutral radical in the (2)E″ state by full dimensional multi-surface wave-packet propagation for NO3 performed using the Multi-Configuration Time Dependent Hartree method. The achieved agreement of the simulations with available experimental data demonstrates the power of the proposed scheme and the high quality of the obtained potential energy surfaces.

Exhaled nitric oxide, nitrite/nitrate levels, allergy, rhinitis and asthma in the EGEA study.

Although interest in biomarkers in the nitrate-nitrite-NO pathway has recently increased, associations between nitrite (NO2(-)) and nitrate (NO3(-)), and asthma, allergic sensitisation and rhinitis remain unclear. The study aimed to evaluate the associations between NO2(-)/NO3(-) and exhaled fraction of nitric oxide (FeNO) levels with asthma, allergic sensitisation and rhinitis. Plasma and exhaled breath condensate (EBC) NO2(-)/NO3(-) and FeNO levels were measured in 523 adults of the French Epidemiological study on Genetics and Environment of Asthma. Allergic sensitisation was defined by a positive skin prick test for at least one aeroallergen. Subjects were classified as non-sensitised, sensitised and as having allergic rhinitis. Plasma NO2 (-)/NO3(-) level was unrelated to any disease phenotypes. EBC NO2(-)/NO3(-) level was unrelated to any asthma phenotypes. EBC NO2(-)/NO3(-) and FeNO levels were correlated in sensitised subjects only (r = 0.21 ± 0.10, p=0.01). EBC NO2(-)/NO3(-) and FeNO levels were higher in sensitised than in non-sensitised subjects (adjusted geometric mean (95% CI): 2.36 (1.96-2.84) versus 1.72 (1.38-2.14) μmol per mg proteins, p=0.008; and 18.3 (16.7-20.0) versus 14.8 (13.3-16.5) ppb, p=0.0006, respectively), with gradual relationships from sensitised subjects to those with allergic rhinitis (p<0.0001). Results suggest that EBC NO2(-)/NO3(-) and FeNO levels may be considered as biological markers of intensity of allergic sensitisation and rhinitis.

Effect of different nitrogen and irrigation treatments on yield and nitrate leaching of summer maize (Zea mays L.) under lysimeter conditions

We examined the effect of different irrigation and nitrogen (N) fertilizer levels on Zea mays L. (maize) on nitrate-nitrogen (NO3−-N) leaching under lysimeter conditions. To do so, we used large lysimeters (2.5m×2.5m×2.0m deep) at the Maize Technological Innovation Center (MTIC) of the northern China plain (NCP), which is located at Shandong Agriculture University (36°09′N, 117°09′E, 128m above sea level) in Taian, China. Our study carried out during 3 cropping seasons (2010–2012) where the crop rotation was corn, grown in the summer, followed by wheat in the winter. Nitrogen leaching mainly occurs during maize growth season in maize–wheat rotation system under natural condition. N management of winter wheat has no significant effect on total N of 0–200cm soil. So, this paper mainly aimed to investigate the summer maize N losses, to provide the data needed to develop best management practices to improve nitrogen use efficiency with the goal to better protect the ecological environment. Our experiment used two maize varieties (Zhongnong 99 [Z99] and Lainong 14 [L14]), two levels of irrigation (525 and 263mm) during the maize growth period, two fertilizer types (urea and manure), and two N fertilization levels (100 and 200kgNha−1), with two experimental replicates. We found that the maximum NO3−-N leaching of maize from the 200-cm soil layer was 77.22kgNha−1 for Z99 and 47.86kgNha−1 for L14 (200-kgNha−1 urea; 525mm irrigation). The minimum and maximum seasonal average NO3−-N concentrations at a depth of 200cm were 41 and 182mg l−1, respectively. Our findings suggest that it may be possible to reduce the amount of NO3−-N leaching from the root zone during the growing season by splitting the application of irrigation and fertilizer treatment according to maize growth stage requirements. With the appropriate combination of irrigation and fertilizer management, levels of NO3−-N leaching during agricultural practices may be minimized.

The correlation of serum levels of leptin, leptin receptor and NO x (NO2 − and NO3 −) in patients with obstructive sleep apnea syndrome

The aim of this study was to investigate the relations between nitric oxide (NO) and leptin levels in a cohort of untreated adult Obstructive sleep apnea syndrome (OSAS) patients. Between June 1, 2012, and January 1, 2013, we evaluated a total of 58 subjects including 36 OSAS patients and 22 healthy controls, both polysomnographically confirmed. Following the completion of polysomnographic evaluation, serum samples were taken at 08:00. Leptin, leptin receptor, NO2 (-) and NO3 (-) levels were analyzed by commercial ELISA kits. Data analysis was performed using the Statistical Package for the Social Sciences (SPSS) version 16.0 (SPSS Inc., Chicago, IL, USA). There was no statistically significant difference between the OSAS patients and control groups with relation to the demographic parameters and body mass index (p > 0.05). Significantly higher serum leptin and plasma NO levels were found in OSAS patients compared to the controls (p < 0.001). In this study, higher leptin levels which were positively correlated with NO levels in OSAS group may indicate a possible link with increased incidence of airway pathologies in these patients.

A 2011 drought event affecting distribution of nutrients and chlorophyll in the Zhujiang River estuary

During the summer of 2011, a severe drought event occurred throughout the Zhujiang (Pearl) River Basin of South China. This decreased runoff into the river, resulting in increased salinity and reduced suspended substance. To examine the effects of this extreme drought on the distribution of nutrients and chlorophyll, we compared two surveys from 2006 and 2011. Results show that dissolved inorganic nitrogen concentration did not change from 2006 to 2011, whereas the proportions of NO2− and NH4+ to DIN in 2011 increased. PO43− concentration was lower in 2011 than in 2006, whereas there was no difference in SiO32− concentration between these years. Correlation coefficients of salinity with levels of NO3−, NO2−, NH4+, PO43− and SiO32− in 2011 were all much higher than those in 2006, suggesting greater conservation of dissolved nutrients during the extreme drought event. Furthermore, calculated amounts of regenerated nitrate and phosphorus and their proportions to observed nutrients in 2011 were much lower than in 2006, indicating that nutrient regeneration decreased during the extreme drought period. Mean concentration of chlorophyll a (Chl-a) was considerably higher in 2011 than in 2006, and a harmful algal bloom of Cochlodinium geminatum was observed in the estuary, owing to water stagnancy and lower turbidity as a consequence of drought. Therefore, the extreme drought event in 2011 changed the composition ratio of nutrients, enhanced nutrient conservative behavior, and reduced nutrient regeneration. This affected some key ecological processes in the estuary.

Influence of the temporal and spatial variation of nitrate reductase, glutamine synthetase and soil composition in the N species content in lettuce (Lactuca sativa)

The variation of nitrate reductase (NR), glutamine synthetase (GS) and N content in lettuce was evaluated at 5 stages of lettuce growth. Soil physicochemical properties and its N content were also assessed to elucidate the soil-to-plant transfer of inorganic N and potential leaching to groundwater. A decrease of NR activity and an increase of NO3− and N-Kjeldahl content in lettuces were observed during plant growth, whereas GS activity and NH4+ increased during the first few weeks of lettuce growth and then decreased. Although the temporal variation was similar in lettuces grown in different soils, quantitative differences were observed, indicating that high NO3− content in soil caused a higher NO3− accumulation in lettuce despite the higher NR activity during the initial stage of plant growth. Higher levels of NO3− and NH4+ were correlated with higher levels of N-Kjeldahl in lettuce suggesting a positive effect of these N species in the biosynthesis of organic forms of N. Soil physicochemical properties influenced the mobility of inorganic N within the groundwater–soil–plant system. Sandy soils with low OM content allowed NO3− leaching, which was confirmed by higher NO3− levels in groundwater. Therefore, lettuces grown in those soils presented lower N content and the inputs of N to the environment were higher.

Changes in Plasma Levels of Vasoactive Factors in Patients Undergoing Abdominal Surgery

Background: To investigate the changes in plasma levels of endothelin (ET), nitric oxide (NO), prostacyclin (PGI2) and thromboxane A2 (TXA2) in patients undergoing abdominal operation. Materials and Methods: Thirty cases of abdominal surgery (14 males, 16 females; mean age 48 ± 11 years, ranging from 24 to 70) were prospectively recruited: Twenty-four cases of cholelithiasis and cholecystitis, 2 cases of peptic ulcer and 4 cases of portal vein hypertension. At five different time points (1-3 days after hospitalization (T1), at surgery beginning, after anesthesia (T2) and at the first (T3), third (T4) and fifth day (T5) after surgery), plasma levels of ET-1, NO2-, NO3-, 6-keto-PGF1α and thromboxane B2 (TXB2), the latter two being stable metabolites of PGI2 and TXA2 respectively, were measured. Results: ET-1 levels increased significantly after anesthesia and surgery (T1 = 69.2 ± 10.7 vs. T2 = 82.4 ± 14.7 vs. T3 = 96.6 ± 22.8 pg/ml, p 2 levels before surgery were significantly lower than that after (T2 = 67.5 ± 52.7 vs. T3 = 157.6 ± 21.8 pg/ml, p 1α were significantly higher than that after anesthesia and surgery (T1 = 180.5 ± 17.8 vs. T2 = 132.1 ± 32.6 vs. T3 = 110.9 ± 31.9 pg/ml, p 2) increased significantly after surgery, while vasodilatory factors (NO and PGI2) decreased significantly after operation. Imbalance in vasoactive factors encourages hypercoagulability and then may play a role in the pathobiology of post-surgery complications, such as deep venous thrombosis (DVT).

Cascading Effects of Climate Change on Forest Ecosystems: Biogeochemical Links Between Trees and Moose in the Northeast USA

The relationship between herbivores, plants and nutrient dynamics, has been investigated in many systems; however, how these relationships are influenced by changing climate has had much less attention. In the northeastern USA, both moose populations and winter climate have been changing. Moose, once extirpated from the region, have made a comeback; while locally, snow depth and duration of snow cover have declined. There is considerable uncertainty in how these changes will interact to influence forested systems. We used small experimental plots and transects along with snow removal (to elicit soil freezing and expose potential forage plants), mechanical browsing, and fecal additions (labeled with 15N) to examine ecosystem responses. We found that snow removal changed moose browsing behavior, with balsam fir more heavily browsed than sugar maple or Viburnum under low snow conditions. Soil freezing alone did not significantly alter N dynamics or selected plant responses, but there were significant interactions with moose activity. The combined effects of moose fecal additions, mechanical browsing, and soil freezing resulted in higher levels of NO3 − leaching under fir and maple, whereas Viburnum had essentially no response to these multiple factors. Our results suggest that declines in snow depth can initiate a cascade of ecosystem responses, beginning with exposure of plants to increased browsing that then triggers a series of responses that can lead to higher N losses, precipitated by decreased N demand in plants compromised by soil freezing damage. Balsam fir may be particularly susceptible to this cascade of multiple stresses.