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BACKGROUND & PURPOSE: It is well established that end-stage renal disease (ESRD) is associated with increased cardiovascular morbidity and mortality both in the adult and pediatric population. Although the underlying molecular mechanisms are poorly understood, compromised nitric oxide (NO) bioactivity has been suggested as a contributing factor. With this in mind, we investigated the effects of hemodialysis on NO homeostasis and bioactivity in blood. METHODS & RESULTS: Plasma and dialysate samples were obtained before and after hemodialysis sessions from adults (n = 33) and pediatric patients (n = 10) with ESRD on chronic renal replacement therapy, and from critically ill adults with acute kidney injury (n = 12) at their first sustained low-efficiency dialysis session. Levels of nitrate, nitrite, cyclic guanosine monophosphate (cGMP) and amino acids relevant for NO homeostasis were analyzed. We consistently found that nitrate and cGMP levels in plasma were significantly reduced after hemodialysis, whereas post-dialysis nitrite and amino acids coupled to NO synthase activity (i.e., arginine and citrulline) were only significantly reduced in adults with ESRD. The amount of excreted nitrate and nitrite during dialysis were similar to daily endogenous levels that would be expected from endothelial NO synthase activity. CONCLUSIONS: Our results show that hemodialysis significantly reduces circulating levels of nitrate and cGMP, indicating that this medical procedure may impair NO synthesis and potentially NO signaling pathways.

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Long-term effects of COD/N ratios on the nitrogen removal performance and bacterial community of an anammox reactor were evaluated by adding a synthetic medium (with glucose) and real anaerobic effluent to a SBR. At a COD/N ratio of 2.8 (COD, 390mg·L(-1)) ammonium removal efficiency was 66%, while nitrite removal remained high (99%). However, at a COD/N ratio of 5.0 (COD, 300mg·L(-1)), ammonium and nitrite removal efficiencies were high (84% and 99%, respectively). High COD, nitrite, and ammonium removal efficiencies (80%, 90% and 95%, respectively) were obtained on adding anaerobically pre-treated municipal wastewater (with nitrite) to the reactor. DGGE revealed that the addition of anaerobic effluent changed the bacterial community structure and selected for DNA sequences related to Brocadia sinica and Chloroflexi. Adding glucose and anaerobic effluent increased denitrifiers concentration threefold. Thus, the possibility of using the anammox process to remove nitrogen from anaerobically pre-treated municipal wastewater was demonstrated.

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Purpose: Standardization of a simple and low cost technique of exhaled breath condensate (EBC) collection to measure nitrite. Methods: Two devices were mounted in polystyrene boxes filled either with crushed ice/salt crystals or dry ice/crushed ice. Blood samples were stored at -70º C for posterior nitrite dosages by chemiluminescence and the Griess reaction. Results: a) The use of crushed ice/dry ice or salt revealed sufficient EBC room air collection, but was not efficient for patients under ventilation support; b) the method using crushed ice/salt collected greater EBC volumes, but the nitrite concentrations were not proportional to the volume collected; c) The EBC nitrite values were higher in the surgical group using both methods; d) In the surgical group the nasal clip use diminished the EBC nitrite concentrations in both methods. Conclusions: The exhaled breath condensate (EBC) methodology collection was efficient on room air breathing. Either cooling methods provided successful EBC collections showing that it is possible to diminish costs, and, amongst the two used methods, the one using crushed ice/salt crystals revealed better efficiency compared to the dry ice method.(AU)

Objetivo: Padronizar técnica simples e barata de coleta do condensado do ar exalado pulmonar (CEP) para medir nitrito. Métodos: Dois dispositivos foram montados em caixas de isopor e preenchidos com gelo picado/sal grosso ou gelo picado/gelo seco. Amostras de sangue foram armazenadas a -70º C para dosagem de nitrito por quimiluminescência e pela reação de Griess. Resultados: a) a utilização de gelo picado/gelo seco ou sal foi eficiente para a coleta em respiração espontânea, mas ineficiente durante ventilação mecânica; b) o método gelo picado/sal coletou volumes maiores, sem aumento proporcional do nitrito; c) os valores do nitrito foram mais elevados no grupo cirúrgico utilizando os dois métodos; d) no grupo cirúrgico com clipe nasal ocorreu diminuição do nitrito em ambos os métodos. Conclusões: A metodologia do condensado do ar exalado pulmonar (CEP) foi eficiente na coleta respirando em ar ambiente. Os dois métodos de congelamento foram eficientes mostrando que é possível diminuir os custos, e, entre os dois métodos utilizados, o uso de gelo picado/sal mostrou melhor eficiência quanto ao volume da coleta do CEP em comparação com o uso de gelo seco.(AU)

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A polyurethane packed-bed-biofilm sequential batch reactor was fed with synthetic substrate simulating the composition of UASB reactor effluents. Two distinct ammonia nitrogen concentrations (125 and 250 mg l(-1)) were supplied during two sequential long-term experiments of 160 days each (320 total). Cycles of 24h under intermittent aeration for periods of 1h were applied, and ethanol was added as a carbon source at the beginning of each anoxic period. Nitrite was the main oxidized nitrogen compound which accumulated only during the aerated phases of the batch cycle. A consistent decrease of nitrite concentration started always immediately after the interruption of oxygen supply and addition of the electron donor. Removal to below detection limits of all nitrogen soluble forms was always observed at the end of the 24h cycles for both initial concentrations. Polyurethane packed-bed matrices and ethanol amendments conferred high process stability. Microbial investigation by cloning suggested that nitrification was carried out by Nitrosomonas-like species whereas denitrification was mediated by unclassified species commonly observed in denitrifying environments. The packed-bed batch bioreactor favored the simultaneous colonization of distinct microbial groups within the immobilized microbial biomass. The biofilm was capable of actively oxidizing ammonium and denitrification at high ratios in intermittent intervals within 24h cycles.

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