Elevated Nitrogen Research Articles

The fate of <sup>15</sup>N-nitrate in mesocosms from five European peatlands differing in long-term nitrogen deposition rate

Abstract. Elevated nitrogen (N) deposition changes the retention, transformation, and fluxes of N in ombrotrophic peatlands. To evaluate such effects we applied a 15N tracer (NH4 15NO3) at a rate of 2.3 g N m−2 yr−1 to mesocosms of five European peatlands with differing long-term N deposition rates for a period of 76 days of dry and 90 days of wet conditions. We determined background N content and moss length growth, and recovered the 15N tracer from the mosses, graminoids, shrubs, the peat, and dissolved N. Background N contents in Sphagnum mosses increased from 5.5 (Degerö Stormyr, deposition < 0.2 g N m−2 yr−1) up to 12.2 mg g−1 (Frölichshaier Sattelmoor, 4.7–6.0 g N m−2 yr−1). In peat from Degerö, nitrate and ammonium concentrations were below 3 mg L−1, whereas up to 30 (nitrate) and 11 mg L−1 (ammonium) was found in peat from Frölichshaier Sattelmoor. Sphagnum mosses (down to 5 cm below surface) generally intercepted large amounts of 15N (0.2–0.35 mg g−1) and retained the tracer most effectively relative to their biomass. Similar quantities of the 15N were recovered from the peat, followed by shrubs, graminoids, and the dissolved pool. At the most polluted sites we recovered more 15N from shrubs (up to 12.4 %) and from nitrate and ammonium (up to 0.7 %). However, no impact of N deposition on 15N retention by Sphagnum could be identified and their length growth was highest under high N background deposition. Our experiment suggests that the decline in N retention at levels above ca. 1.5 g m−2 yr−1, as expressed by elevated near-surface peat N content and increased dissolved N concentrations, is likely more modest than previously thought. This conclusion is related to the finding that Sphagnum species can apparently thrive at elevated long-term N deposition rates in European peatlands.

Abstract TP256: Mouse Model of Uremic Cerebral Microbleeds

Introduction: Cerebral microbleeds are more common in chronic kidney disease (CKD) and dialysis patients compared to the general population. Diminished kidney function alone appears to be a risk factor for microbleeds, independent of age and hypertension. Microbleed burden in CKD patients is associated with increased risk of future hemorrhagic stroke and with cognitive dysfunction. The mechanisms that drive uremic microbleed formation are unclear. Hypothesis: We hypothesized that CKD mice are predisposed to develop cerebral microhemorrhages (the pathologic substrate of microbleeds), and that a standardized inflammatory stimulus (lipopolysaccharide, LPS) will amplify microhemorrhage burden in CKD mice compared to non-CKD controls (CTL). We also hypothesized that uremia induces depletion of tight junction proteins, altering blood-brain barrier integrity and representing a potential mechanism of microbleed formation. Methods: Animal groups included CTL (n=3), CKD (n=3), CTL+LPS (n=5) and CKD+LPS (n=5). CKD induction in male C57BL/6 mice was achieved via nephrotoxic adenine diet x18 days. Two weeks following CKD induction, CKD and control mice were treated with LPS 1 mg/kg i.p. dosed at 0, 6 and 24 hours. Brains were harvested one week after LPS injections and 40-micron sections were stained using Prussian blue to identify microhemorrhages. Immunohistochemistry was performed for the blood-brain barrier tight junction protein claudin-5. Results: CKD mice had significantly elevated blood urea nitrogen, and tubulointerstitial fibrosis was present on kidney histology. Total number of microhemorrhages per brain was 2.3±1.5 (mean ± standard error of the mean) for CTL mice, 8.3±1.5 for CKD mice, 23.2±4.2 for CTL+LPS mice, and 27.6±6.2 for CKD+LPS mice (p<0.05 for CKD+LPS vs. CTL). Immunostaining showed decreased claudin-5 expression in CKD mice compared to CTL. Conclusions: We have generated a mouse model that will facilitate future mechanistic studies in the field of uremic microbleeds. Our initial findings suggest that CKD alters blood-brain barrier integrity and that inflammation amplifies development of microbleeds in CKD.

Relationship between Anti-Ds-DNA Antibodies and Abnormal Kidney Function Tests in Patients with Lupus Nephritis

The majority of patients with Lupus Nephritis (LN) usually have abnormal findings of kidney function tests. Severe glomerular damage may be observed in some patients and requires prompt therapeutic interventions. High titer levels of anti-ds-DNA antibodies may correlate to some extent with disease activity in lupus nephritis patients. The purpose of this study was to evaluate the relationship between anti-ds-DNA antibody titers and abnormal kidney function tests in patients with lupus nephritis. A total of seventy patients with lupus nephritis and fifty healthy controls were enrolled in this study. Blood samples were collected and labeled from study patients and controls for certain hematological, biochemical and immunological investigations. Anti-ds-DNA antibodies were tested by using IgG-ELISA test. It was shown that 74% of lupus nephritis patients showed positive results for anti-ds-DNA antibodies in their serum specimens (p-value <0.01). Sensitivity and specificity of the anti-ds-DNA antibody test for the diagnosis of lupus nephritis were 74 and 100%, respectively. Anaemia, hypoalbuminemia, fasting hyperglycemia and elevated blood urea nitrogen were significantly associated with lupus nephritis activity. Further studies are required to study genomic and unprecedented biomarkers associated with anti-ds-DNA antibodies in patients with lupus nephritis to develop our perception of this autoimmune disease.

The formation of a subsurface anticyclonic eddy in the Peru‐Chile Undercurrent and its impact on the near‐coastal salinity, oxygen, and nutrient distributions

AbstractThe formation of a subsurface anticyclonic eddy in the Peru‐Chile Undercurrent (PCUC) in January and February 2013 is investigated using a multiplatform four‐dimensional observational approach. Research vessel, multiple glider, and mooring‐based measurements were conducted in the Peruvian upwelling regime near 12°30'S. The data set consists of &gt;10,000 glider profiles and repeated vessel‐based hydrography and velocity transects. It allows a detailed description of the eddy formation and its impact on the near‐coastal salinity, oxygen, and nutrient distributions. In early January, a strong PCUC with maximum poleward velocities of ∼0.25 m/s at 100–200 m depth was observed. Starting on 20 January, a subsurface anticyclonic eddy developed in the PCUC downstream of a topographic bend, suggesting flow separation as the eddy formation mechanism. The eddy core waters exhibited oxygen concentration of &lt;1 μmol/kg, an elevated nitrogen deficit of ∼17 μmol/L, and potential vorticity close to zero, which seemed to originate from the bottom boundary layer of the continental slope. The eddy‐induced across‐shelf velocities resulted in an elevated exchange of water masses between the upper continental slope and the open ocean. Small‐scale salinity and oxygen structures were formed by along‐isopycnal stirring, and indications of eddy‐driven oxygen ventilation of the upper oxygen minimum zone were observed. It is concluded that mesoscale stirring of solutes and the offshore transport of eddy core properties could provide an important coastal open ocean exchange mechanism with potentially large implications for nutrient budgets and biogeochemical cycling in the oxygen minimum zone off Peru.

Microbial properties explain temporal variation in soil respiration in a grassland subjected to nitrogen addition.

The role of soil microbial variables in shaping the temporal variability of soil respiration has been well acknowledged but is poorly understood, particularly under elevated nitrogen (N) deposition conditions. We measured soil respiration along with soil microbial properties during the early, middle, and late growing seasons in temperate grassland plots that had been treated with N additions of 0, 2, 4, 8, 16, or 32 g N m−2 yr−1 for 10 years. Representing the averages over three observation periods, total (Rs) and heterotrophic (Rh) respiration were highest with 4 g N m−2 yr−1, but autotrophic respiration (Ra) was highest with 8 to 16 g N m−2 yr−1. Also, the responses of Rh and Ra were unsynchronized considering the periods separately. N addition had no significant impact on the temperature sensitivity (Q10) for Rs but inhibited the Q10 for Rh. Significant interactions between observation period and N level occurred in soil respiration components, and the temporal variations in soil respiration components were mostly associated with changes in microbial biomass carbon (MBC) and phospholipid fatty acids (PLFAs). Further observation on soil organic carbon and root biomass is needed to reveal the long-term effect of N deposition on soil C sequestration.

Spatial response of coastal marshes to increased atmospheric CO2

The elevation and extent of coastal marshes are dictated by the interplay between the rate of relative sea-level rise (RRSLR), surface accretion by inorganic sediment deposition, and organic soil production by plants. These accretion processes respond to changes in local and global forcings, such as sediment delivery to the coast, nutrient concentrations, and atmospheric CO2, but their relative importance for marsh resilience to increasing RRSLR remains unclear. In particular, marshes up-take atmospheric CO2 at high rates, thereby playing a major role in the global carbon cycle, but the morphologic expression of increasing atmospheric CO2 concentration, an imminent aspect of climate change, has not yet been isolated and quantified. Using the available observational literature and a spatially explicit ecomorphodynamic model, we explore marsh responses to increased atmospheric CO2, relative to changes in inorganic sediment availability and elevated nitrogen levels. We find that marsh vegetation response to foreseen elevated atmospheric CO2 is similar in magnitude to the response induced by a varying inorganic sediment concentration, and that it increases the threshold RRSLR initiating marsh submergence by up to 60% in the range of forcings explored. Furthermore, we find that marsh responses are inherently spatially dependent, and cannot be adequately captured through 0-dimensional representations of marsh dynamics. Our results imply that coastal marshes, and the major carbon sink they represent, are significantly more resilient to foreseen climatic changes than previously thought.

Abstract 12975: Cardiac I-123 Metaiodobenzylguanidine Imaging Predicts the Risk of Cardiac Death in Patients With Chronic Heart Failure, Irrespective of Blood Urea Nitrogen to Creatinine Ratio: A Long-Term Follow Up Study

Background: Cardiac I-123 metaiodobenzylguanidine (MIBG) imaging, which reflects cardiac sympathetic activity, provides prognostic information in patients with chronic heart failure (CHF). On the other hand, elevated blood urea nitrogen to creatinine ratio (BUN/Cr), a surrogate for renal neurohumoral activation, is associated with poor outcome in patients with heart failure. However, there is no information available on the prognostic value of cardiac MIBG imaging in patients with CHF, relating to BUN/Cr. Methods: We studied 109 CHF outpatients (NYHA class:2.1±0.6, ischemic origin:52%) with left ventricular ejection fraction &lt;40% (30±8%) in our prospective cohort study. At the enrollment, we measured serum level of BUN and Cr, and performed cardiac MIBG scintigraphy. Elevated BUN/Cr was defined as &gt;20. The cardiac MIBG washout rate (WR) was calculated from the chest anterior view images obtained at 20 and 200 min after isotope injection. Abnormal WR was defined as &gt;27%. Results: Forty patients had elevated BUN/Cr, and 55 patients had abnormal WR. During a follow up period of 7.5±4.2 yrs, 36 of 109 patients had cardiac death. At multivariate Cox analysis, WR was significantly independently associated with cardiac death in group with both elevated BUN/Cr (p=0.02) and normal BUN/Cr (p=0.004). Kaplan-Meier analysis showed that patients with abnormal WR had a higher risk of cardiac death than those with normal WR, in group with both elevated BUN/Cr (48%[11/23] vs 6%[1/17], p=0.02, adjusted hazard ratio 11.8[95%CI 1.5-92.2]) and normal BUN/Cr (55%[18/33] vs 17%[6/36], p=0.001, adjusted hazard ratio 4.6[95%CI 1.8-11.6]). Conclusion: The cardiac MIBG imaging could predict the risk of cardiac death in CHF, irrespective of BUN/Cr.

Long-term reactive nitrogen loading alters soil carbon and microbial community properties in a subalpine forest ecosystem

Elevated nitrogen (N) deposition due to increased fossil fuel combustion and agricultural practices has altered global carbon (C) cycling. Additions of reactive N to N-limited environments are typically accompanied by increases in plant biomass. Soil C dynamics, however, have shown a range of different responses to the addition of reactive N that seem to be ecosystem dependent. We evaluated the effect of N amendments on biogeochemical characteristics and microbial responses of subalpine forest organic soils in order to develop a mechanistic understanding of how soils are affected by N amendments in subalpine ecosystems. We measured a suite of responses across three years (2011–2013) during two seasons (spring and fall). Following 17 years of N amendments, fertilized soils were more acidic (control mean 5.09, fertilized mean 4.68), and had lower %C (control mean 33.7% C, fertilized mean 29.8% C) and microbial biomass C by 22% relative to control plots. Shifts in biogeochemical properties in fertilized plots were associated with an altered microbial community driven by reduced arbuscular mycorrhizal (control mean 3.2 mol%, fertilized mean 2.5 mol%) and saprotrophic fungal groups (control mean 17.0 mol%, fertilized mean 15.2 mol%), as well as a decrease in N degrading microbial enzyme activity. Our results suggest that decreases in soil C in subalpine forests were in part driven by increased microbial degradation of soil organic matter and reduced inputs to soil organic matter in the form of microbial biomass.

Exceedance of critical loads and of critical limits impacts tree nutrition across Europe

Abstract Key message Exceedance of critical limits in soil solution samples was more frequent in intensively monitored forest plots across Europe with critical loads for acidity and eutrophication exceeded compared to other plots from the same network. Elevated inorganic nitrogen concentrations in soil solution tended to be related to less favourable nutritional status. Context Forests have been exposed to elevated atmospheric deposition of acidifying and eutrophying sulphur and nitrogen compounds for decades. Critical loads have been identified, below which damage due to acidification and eutrophication are not expected to occur. Aims We explored the relationship between the exceedance of critical loads and inorganic nitrogen concentration, the base cation to aluminium ratio in soil solutions, as well as the nutritional status of trees. Methods We used recent data describing deposition, elemental concentrations in soil solution and foliage, as well as the level of damage to foliage recorded at forest plots of the ICP Forests intensive monitoring network across Europe. Results Critical loads for inorganic nitrogen deposition were exceeded on about a third to half of the forest plots. Elevated inorganic nitrogen concentrations in soil solution occurred more frequently among these plots. Indications of nutrient imbalances, such as low magnesium concentration in foliage or discolouration of needles and leaves, were seldom but appeared more frequently on plots where the critical limits for soil solution were exceeded. Conclusion The findings support the hypothesis that elevated nitrogen and sulphur deposition can lead to imbalances in tree nutrition.

Wastewater Nitrogen Contributions to Coastal Plain Watersheds, NC, USA

Nitrogen inputs to coastal watersheds have been linked to eutrophication. However, the role that domestic sources of wastewater play in contributing nitrogen to coastal watersheds is not well known in the southeastern USA. In a yearlong study (2011–2012), nitrogen concentrations were compared in watersheds served by septic systems and a centralized sewer system in the Coastal Plain of North Carolina. Surface and groundwater samples from septic systems and sewer watersheds were analyzed for total dissolved nitrogen (TDN), total nitrogen, and nitrogen and oxygen isotopes in nitrate. Groundwater beneath the drainfield and adjacent to streams had median concentrations of TDN at 5.9 and 4.4 mg/L, respectively. Additionally, median groundwater-transported loads of TDN to the stream from septic systems sites (0.6 kg-TDN/year) were significantly greater than sites in sewer watersheds (0.2 kg-TDN/year). Isotopic analyses revealed that effluent from septic systems was the primary source of nitrate in watersheds served by septic systems, while fertilizer and/or soil organic matter were dominant sources of nitrate in sewer watersheds. Nitrogen exported from septic systems contributed to elevated nitrogen concentrations in groundwater and streams throughout the watershed, whereas nitrogen exports from sewers were focused at a single point source and affected surface water concentrations. Based on watershed TDN exports from septic systems minus TDN exports from sewers watersheds, it was estimated that septic systems contributed 1.6 kg TDN/ha/year to watershed exports of TDN. Overall, septic systems and sewers contributed to elevated nitrogen loading and should be considered in nutrient-sensitive watershed management.

Consequences of long-term severe industrial pollution for aboveground carbon and nitrogen pools in northern taiga forests at local and regional scales

Boreal coniferous forests act as an important sink for atmospheric carbon dioxide. The overall tree carbon (C) sink in the forests of Europe has increased during the past decades, especially due to management and elevated nitrogen (N) deposition; however, industrial atmospheric pollution, primarily sulphur dioxide and heavy metals, still negatively affect forest biomass production at different spatial scales. We report local and regional changes in forest aboveground biomass, C and N concentrations in plant tissues, and C and N pools caused by long-term atmospheric emissions from a large point source, the nickel–copper smelter in Monchegorsk, in north-western Russia. An increase in pollution load (assessed as Cu concentration in forest litter) caused C to increase in foliage but C remained unchanged in wood, while N decreased in foliage and increased in wood, demonstrating strong effects of pollution on resource translocation between green and woody tissues. The aboveground C and N pools were primarily governed by plant biomass, which strongly decreased with an increase in pollution load. In our study sites (located 1.6–39.7km from the smelter) living aboveground plant biomass was 76 to 4888gm−2, and C and N pools ranged 35–2333gCm−2 and 0.5–35.1gNm−2, respectively. We estimate that the aboveground plant biomass is reduced due to chronic exposure to industrial air pollution over an area of about 107,200km2, and the total (aboveground and belowground) loss of phytomass C stock amounts to 4.24×1013gC. Our results emphasize the need to account for the overall impact of industrial polluters on ecosystem C and N pools when assessing the C and N dynamics in northern boreal forests because of the marked long-term negative effects of their emissions on structure and productivity of plant communities.

Preclinical efficacy of Dexmedetomidine on spinal cord injury provoked oxidative renal damage

Purpose: Oxidative renal injury is the mainstay in patients with spinal cord injury (SCI) and it may eventuate to chronic renal failure. In our study, we investigated the potential of α2-adrenoreceptor agonist Dexmedetomidine (Dex) in ameliorating SCI provoked oxidative renal assault. Methods: Complete SCI was generated by surgical transaction of the cord at the T10–12 level. Dex administration (50 mcg/kg, b.wt, intraperitoneally) was initiated 12 h after the surgery for 10 days. Then, blood was collected and kidneys were removed to evaluate the efficacy of Dex on post-SCI renal complications. Results: Dex treatment significantly attenuated elevated serum creatinine and blood urea nitrogen in SCI rats to normalcy. Further in SCI rats elevated level of MDA, protein carbonyl and myeloperoxidase (MPO) were observed and Dex treatment significantly attenuated these toxic manifestations to normalcy. Besides in SCI rats, the antioxidants (SOD, CAT, Gpx and GST and GSH) levels were significantly diminished and Dex treated rats significantly restored the antioxidants level in renal tissue to normalcy. Notably, in our study the protein expression of inflammatory cytokines (TNF-α and IL-6) and cleaved caspase-3 were upregulated in renal tissue of SCI rats. Fascinatingly, Dex treatment downregulated the protein expression of TNF-α, IL-6 and cleaved caspase-3 by anti-inflammatory, antiapoptotic mechanism. Furthermore, SCI rats displayed upregulated protein expression of kidney of SCI rats. Dex treatment diminished the renal apoptosis by downregulating the cleaved caspase-3 expression. Conclusion: Taken together, these results accentuate that Dex may be a beneficial clinical agent to combat post-SCI renal complications.

A test of metabolic and consumptive responses to local and global perturbations: enhanced resources stimulate herbivores to counter expansion of weedy species

The capacity of natural systems to resist environmental change underpins ecosystem stability, e.g. the persistence of kelp-dominated states which are sometimes displaced by subordinates or weedy species (i.e. algal turfs). Perturbation by resource enhancement at global (e.g. CO2 emissions) through local scales (e.g. nutrient pollution) increases the probability of turf domination, yet these same resources stimulate an increase in per capita consumption of turfs by herbivores. We test whether such resource perturbation can stimulate herbivores to absorb the additional productivity of turfs that cause kelp displacement. We tested the hypotheses that (1) elevated nitrogen (N) and carbon dioxide (CO2) not only stimulate an increase in consumptive rates, but also stimulate an increase in underlying metabolic rates of gastropod herbivores, so that (2) enhanced primary productivity is countered by herbivory. We reveal that elevated nitrogen and CO2 stimulated an elevation in rates of consumption in proportion to an increase in metabolic rate of grazers. Subsequently, grazers consumed proportionately greater cover of turfs to counter turf expansion. Resource enrichment, therefore, can stimulate metabolic and consumptive activity of herbivores to absorb the additional productivity of opportunistic species. Hence, the competitive potential of subordinates to displace community dominants may be checked by the very resources that otherwise drive instability.

Physiological Responses of Two Moss Species to the Combined Stress of Water Deficit and Elevated Nitrogen Deposition. I. Secondary Metabolism

Premise of research. It has been well documented that secondary metabolites in mosses can protect mosses from pathogen or herbivore attacks, but their functions in abiotic stress are poorly understood. Thus, we have investigated effects of water deficit and high nitrogen (N) on secondary metabolism in two moss species.Methodology. KNO3 or NH4Cl was supplied to Pogonatum cirratum subsp. fuscatum and Hypnum plumaeforme at rates of 20–60 kg N hm−2 for 1 yr, water was then withheld for 12 d, and finally a 10-d recovery treatment was applied. Indexes of oxidative stress (superoxide dismutase [SOD], malondialdehyde [MDA]) and secondary metabolism were determined after the water-withholding and recovery treatments, respectively.Pivotal results. Both ammonium and nitrate supply stimulated SOD activity and MDA accumulation as well as the synthesis of phenylpropanoids, triterpenes, and total alkaloids. Water-deficit stress induced oxidative stress in both moss species, and N application exacerbated the oxidative stress. Water deficit inhibited SOD and L-phenylalanine ammonia-lyase activities and changed their phenylpropanoid profiles (with interspecific differences). Triterpene accumulation was stimulated by water deficit in H. plumaeforme (but not in P. cirratum), while alkaloid accumulation was stimulated in both mosses. After the 10-d recovery period, the N treatments generally still had significant effects on SOD activity and secondary metabolite contents, and water deficit still had effects on contents of some phenolics and alkaloids. However, SOD activity in the water-deficit-treated P. cirratum samples was restored after recovery, indicating that it may play an important role in recovery from stress induced by water deficit.Conclusions. The secondary metabolism of both mosses is intimately linked to their antioxidant mechanisms. Phenylpropanoids, triterpenes, and alkaloids may mark moss responses to stress and therefore present a useful method for environmental monitoring in the mosses.

Responses of soil acid phosphatase and beta-glucosidase to nitrogen and phosphorus addition in two subtropical forests in southern China

Elevated nitrogen (N) deposition has dramatically altered soil phosphorus (P) and carbon (C) cycles in forests and altered extracellular enzyme activity. However, the effects of N addition and the interactive effects of combined N and P additions on soil enzyme (e.g. phosphatase and glucosidase) activity in different types of forests (young vs. old-growth) remain unclear. To better understand this, a long-term N–P fertilization experiment was initiated in January 2007 in two subtropical forests (an old-growth monsoon evergreen broadleaf forest (MEBF) and a young Masson pine forest (MPF)) in southern China. Four treatments were established, including control (no nutrient addition), N addition (150 kg Nha−1yr−1), P addition (150 kg Pha−1yr−1) and NP addition (150 kg Nha−1yr−1 plus 150 kg Pha−1yr−1). Soil physicochemical properties, acid phosphatase (APA-s) and β-glucosidase (BGA-s) activity per soil were measured in July 2012 and July 2013. Both APA-s and BGA-s were higher in MEBF than in MPF. N addition significantly stimulated APA-s in MEBF and BGA-s in MPF. P addition significantly suppressed APA-s in both forests and BGA-s in MEBF. Moreover, P addition decreased the stimulating effect of N addition on APA-s in MEBF and on BGA-s in MPF. Our results suggest that (1) N addition may exacerbate soil P limitation in old-growth forests and result in the deficiency of easily available C in young forests and (2) P addition may mitigate these negative effects of N addition in both forest types. Our findings suggest that P fertilization may be an effective practice to improve soil P availability in old-growth forests and soil C availability in young forests under N deposition condition.

Mineral elements of subtropical tree seedlings in response to elevated carbon dioxide and nitrogen addition.

Mineral elements in plants have been strongly affected by increased atmospheric carbon dioxide (CO2) concentrations and nitrogen (N) deposition due to human activities. However, such understanding is largely limited to N and phosphorus in grassland. Using open-top chambers, we examined the concentrations of potassium (K), calcium (Ca), magnesium (Mg), aluminum (Al), copper (Cu) and manganese (Mn) in the leaves and roots of the seedlings of five subtropical tree species in response to elevated CO2 (ca. 700 μmol CO2 mol-1) and N addition (100 kg N ha-1 yr-1) from 2005 to 2009. These mineral elements in the roots responded more strongly to elevated CO2 and N addition than those in the leaves. Elevated CO2 did not consistently decrease the concentrations of plant mineral elements, with increases in K, Al, Cu and Mn in some tree species. N addition decreased K and had no influence on Cu in the five tree species. Given the shifts in plant mineral elements, Schima superba and Castanopsis hystrix were less responsive to elevated CO2 and N addition alone, respectively. Our results indicate that plant stoichiometry would be altered by increasing CO2 and N deposition, and K would likely become a limiting nutrient under increasing N deposition in subtropics.

Copper nanoparticle (CuNP) nanochain arrays with a reduced toxicity response: a biophysical and biochemical outlook on Vigna radiata.

Copper deficiency or toxicity in agricultural soil circumscribes a plant's growth and physiology, hampering photochemical and biochemical networks within the system. So far, copper sulfate (CS) has been used widely despite its toxic effect. To get around this long-standing problem, copper nanoparticles (CuNPs) have been synthesized, characterized, and tested on mung bean plants along with commercially available salt CS, to observe morphological abnormalities enforced if any. CuNPs enhanced photosynthetic activity by modulating fluorescence emission, photophosphorylation, electron transport chain (ETC), and carbon assimilatory pathway under controlled laboratory conditions, as revealed from biochemical and biophysical studies on treated isolated mung bean chloroplast. CuNPs at the recommended dose worked better than CS in plants in terms of basic morphology, pigment contents, and antioxidative activities. CuNPs showed elevated nitrogen assimilation compared to CS. At higher doses CS was found to be toxic to the plant system, whereas CuNP did not impart any toxicity to the system including morphological and/or physiological alterations. This newly synthesized polymer-encapsulated CuNPs can be utilized as nutritional amendment to balance the nutritional disparity enforced by copper imbalance.

Abstract W MP78: Intravascular Volume Delpetion in Hypertensive ED Stroke Patients

Objective: The hypertensive response in acute stroke may mask patients who could be volume depleted. Our objective was to determine the incidence of stroke patients that are volume depleted despite hypertension. This is a pilot study using sonographic markers of volume status as compared to common clinical indicators of volume status. Methods: This was a prospective cohort study of suspected ischemic stroke patients with a NIHSS ≥ 4 and symptoms onset &lt; 24 hours. Exclusion criteria were pregnancy, age &lt; 18, or ICH. Trained investigators performed a sonographic assessment of volume status. An IVC collapsibility index (IVC-CI) &gt; 50% was used to define volume depletion. Investigators collected demographic and clinical information, and laboratory markers of dehydration (elevated blood urea nitrogen to creatinine ratio, hemoconcentration or high serum osmolality). A standardized questionnaire was given to treating clinicians who were blinded to the IVC-CI. They indicated their assessment of the patient's volume status. The analysis excluded subjects ultimately diagnosed with a stroke mimic. Analysis incorporated descriptive and regression statistics using SAS 9.3. The local IRB approved the study. Results: 23 subjects were enrolled, 4 had stroke mimics and were excluded from analysis. Mimics consisted of psychogenic disorders and myelopathy. The mean age was 64 years, 89% were Black, 68% female, and 95% had preexisting HTN. The mean NIHSS was 9.2, the mean time from symptom onset 309 minutes and the mean presenting SBP 170 ± 31 mmHg. 68% of subjects had a cortical infarct on MRI and the remaining had lacunar infarcts. The mean IVC-CI was 70 ± 21% and 84% (95% CI 68 - 100%) of subjects had IVC-CI &gt; 50%. Laboratory markers of dehydration were present in 5% of subjects. Treating physicians classified 29% as subjects as hypovolemic. There was no correlation between IVC-CI and SBP, NIHSS, infarct location or laboratory markers of dehydration (r = 0.04 - 0.29, p &gt; 0.23). Conclusions: This pilot study suggests that despite being hypertensive, the majority of ED stroke patients have US indications of volume depletion and may be able to tolerate volume expansion. Future studies may identify which patients have improvement in cerebral perfusion with volume expansion.

Phosphate addition enhanced soil inorganic nutrients to a large extent in three tropical forests.

Elevated nitrogen (N) deposition may constrain soil phosphorus (P) and base cation availability in tropical forests, for which limited evidence have yet been available. In this study, we reported responses of soil inorganic nutrients to full factorial N and P treatments in three tropical forests different in initial soil N status (N-saturated old-growth forest and two less-N-rich younger forests). Responses of microbial biomass, annual litterfall production and nutrient input were also monitored. Results showed that N treatments decreased soil inorganic nutrients (except N) in all three forests, but the underlying mechanisms varied depending on forests: through inhibition on litter decomposition in the old-growth forest and through Al3+ replacement of Ca2+ in the two younger forests. In contrast, besides great elevation in soil available P, P treatments induced 60%, 50%, 26% increases in sum of exchangeable (K++Ca2++Mg2+) in the old-growth and the two younger forests, respectively. These positive effects of P were closely related to P-stimulated microbial biomass and litter nutrient input, implying possible stimulation of nutrient return. Our results suggest that N deposition may result in decreases in soil inorganic nutrients (except N) and that P addition can enhance soil inorganic nutrients to support ecosystem processes in these tropical forests.

Predicting early mortality in resectable pancreatic adenocarcinoma: A cohort study.

414 Background: Overall survival after pancreatic cancer resection remains poor. A subgroup of patients die early (&lt;6 months) and understanding factors associated with early mortality may help identify high-risk patients. The Khorana Score, including baseline hemoglobin, leukocyte and platelet counts, and body mass index [Khorana et al, Blood, 2008], has been shown to be associated with early mortality in solid tumors [Ay et al; Kuderer et al]. We evaluated the role of this score and other prognostic variables in predicting early mortality following resection. Methods: We conducted a cohort study of consecutive patients who underwent surgical resection for pancreatic cancer from January 2006 through June 2013 and were followed at the Cleveland Clinic. Baseline (diagnosis +/- 30 days) parameters were used to define patients as high-risk (Score &gt;=3). Statistically significant univariable associations and a priori prognostic variables were tested in multivariable models; adjusted hazard ratios (HR) are presented. Results: The study population comprised 334 patients. Median age was 67 years; 50% were female; 86% were Caucasian. Pancreatic head was the primary site for 73%; 67% were T3 and 63% were N1 tumors. Median Khorana score was 2; 152 patients (47%) were high-risk. Adjunctive treatment included chemotherapy (70%) and radiation (40%). Post-operative (30-day) mortality was 0.9%. Six-month mortality for the entire cohort was 9.4%, with significantly higher rates for high-risk patients (13.4% vs. 5.6%, p=0.02). In univariable analyses, Khorana score, low hemoglobin, and elevated blood urea nitrogen (BUN) were associated with early mortality; T- and N-stage, as well as margin status (R0/R1), were not. In multivariable analyses (n=326), Khorana score (HR high-risk = 2.31, p=0.039) and elevated BUN (HR = 4.34, p&lt;0.001) were associated with early mortality. Conclusions: Patients at high risk for early mortality after resection of pancreatic adenocarcinoma can be identified using simple baseline patient-related clinical and laboratory parameters rather than tumor characteristics. Future studies could evaluate the benefit of pre-operative interventions targeting patients at high risk for early mortality.