Total Nitrite Concentrations Research Articles

Improvement of oxidative stress and immunity by melatonin: An age dependent study in golden hamster

Reactive oxygen species (ROS) have been proposed to play an important role in balancing the pro- and antioxidant homeostasis during aging. Melatonin has been suggested as an effective free radical scavenger that might have a role during the process of aging. We observed, that melatonin administration (25μg/100g body weight for 30days) significantly augments the activity of anti-oxidative enzymes like superoxide dismutase (SOD), catalase and glutathione peroxidase (GPx) in the plasma, spleen and bone marrow (BM) of young (6weeks), adult (30weeks) and old aged (2.5years) male golden hamster, Mesocricetus auratus. A sharp decline in generation of ROS was observed in peripheral blood mononuclear cells (PBMC) and splenocytes upon melatonin administration in different age group of hamsters. Reduction in the level of thiobarbituric acid-reactive substances (TBARS) and total nitrite and nitrate concentration as metabolites and indicators of nitric oxide (NO) in plasma, spleen and BM were observed along with night time (22:00h) melatonin concentration in different age group of hamsters after administration of melatonin and compared to the control group (treated with 0.9% saline). General immune parameters like proliferation of splenocytes, PBMC and colony forming ability of GM-CFU were observed following melatonin treatment in different age group, although it was low only in aged hamsters compared to the young and adult. Our data indicates that the age related increase of oxidative load and simultaneously augments the general immunity in aged hamsters.

SEXUAL ABSTINENCE AND IMMOBILISATION STRESS DECREASED NITRATE + NITRITE CONCENTRATION AND INCREASED NECROTIC OF PENILE CORPUS CAVERNOSUM SMOOTH MUSCLE AND ENDOTHELIAL CELLS OF ADULT MALE MICE

Sexual intercourse in adult people is not only related to reproduction,recreation and better relation but also for maintaining good health. Regular andfrequent sexual intercourse has protective role for cardiovascular disease, malignancyand often related with longevity. On the contrary less frequent sexual intercourse isoften correlated to early death and reproductive organ disorders. One main factorwhich involve in any process related to sexual intercourse is nitric oxide. Thisresearch aims to know the declination of total nitrate and nitrite concentration as themain oxidation product of nitric oxide and necrosis of the endothelial and smoothmuscles of corpus cavernosum after three month sexual intercourse abstinence andstress immobilization.By randomized pretest-posttest control group design, the research wasconducted in adult male mice (Mus musculus) which were divided into four groups.each consisted of seven mice. One group as a control and the other three wereexposed to sexual abstinence, immobilization stress and the combination of sexualabstinence and immobilization stress in three months period. The investigation wascarried out to the penile total nitrate and nitrite concentration and the histologicalchanges of the middle part of the penile shaft. To know the degree of lesion then thecalculation of the histologic features was done in five view fields of every preparat.The result was compared to control group.In this research, the mean of total nitrate and nitrite decline and the lowest wasfound in the combine intervention groups with significance level p < 0,005. Thecorpus cavernosum in the intervention groups showed multifocal necrosis onendothelial and smooth muscle cells of corpus cavernosum with picnotic nuclei,irregular form and dark colour. Some muscle cells are lysis. These features werefound in three among seven samples in sexual abstinence group, two among sevensamples in immobilization stress group and in all samples of combined interventiongroup.Conclusions can be drawn from this research are that the sexual abstinence,immobilization stress and the combine interventions decline the nitrate and nitriteconcentrations and induce endothelial and smooth muscle cells necrosis of the copuscavernosum.

Improved blood pressure, nitric oxide and asymmetric dimethylarginine are independent after bariatric surgery

Obesity is associated with hypertension, but the exact mechanism is not fully understood. Bariatric surgery significantly decreases weight and blood pressure (BP). Low plasma nitric oxide (NO) and raised asymmetric dimethylarginine (ADMA), an endogenous inhibitor of NO, concentrations are associated with both obesity and hypertension. Correlations between the changes in these parameters were studied after bariatric surgery. Weight, BP, plasma ADMA and NO were measured in 29 obese patients (24 female, 5 male) before and six weeks after bariatric surgery. Patients were 39.2 ± 1.2 (mean ± SEM) years old and weighed 126 ± 3 kg. Six weeks after the surgery, patients had lost 10 ± 0.7 kg (P < 0.0001) and mean arterial pressure (MAP) decreased by 11 ± 1.0 mmHg (P < 0.0001). The plasma ADMA concentration decreased by 24 ± 2% from 5 ± 0.4 to 4.0 ± 0.3 μmol/L (P < 0.0001). The plasma total nitrite concentration increased by 15 ± 1% from 51.4 ± 2.6 to 60 ± 3 μmol/L (P < 0.0001). The correlation between the decrease of ADMA and increase of NO subsequent to weight loss was significant (P < 0.0001). However, MAP was not correlated to the changes in ADMA or NO. After bariatric surgery, beneficial changes in BP, NO and ADMA occur, but our findings suggest that these BP changes are independent of changes in the NO-ADMA axis. Other causes for the changes in BP should therefore be considered.

Effect of pH, substrate and free nitrous acid concentrations on ammonium oxidation rate

Respirometric techniques have been used to determine the effect of pH, free nitrous acid (FNA) and substrate concentration on the activity of the ammonium oxidizing bacteria (AOB) present in an activated sludge reactor. With this aim, bacterial activity has been measured at different pH values (ranging from 6.2 to 9.7), total ammonium nitrogen concentrations (ranging from 0.1 to 10mgTANL−1) and total nitrite concentrations (ranging from 3 to 43mgNO2–NL−1). According to the results obtained, the most appropriate kinetic expression for the growth of AOB in activated sludge reactors has been established. Substrate half saturation constant and FNA and pH inhibition constants have been obtained by adjusting model predictions to experimental results. Different kinetic parameter values and different Monod terms should be used to model the growth of AOB in activated sludge processes and SHARON reactors due to the different AOB species that predominate in both systems.

Effects of feed loading on nitrogen balances and fish performance in replicated recirculating aquaculture systems

This study investigated the effects of applying four fixed feed loadings to three replicated recirculating aquaculture systems (RAS) on water quality changes, nitrogenous balances and growth performance of rainbow trout (Oncorhynchus mykiss).Feed loadings ranged from 1.6 to 6.3kgfeed/m3 make-up water, with a constant make-up water renewal of 4.7% of total water volume per day in all twelve RAS. Fish densities ranged from 14 to 92kg/m3 during the prolonged trial of 10weeks. Selected water quality parameters were measured during two intensive sampling campaigns, evaluating biofilter nitrification performance and diurnal patterns of total ammonia nitrogen (TAN) and nitrite concentrations. No fish mortality occurred during the study. Feed conversion ratios varied between 0.91±0.04 and 0.95±0.02, and were unaffected by feeding load. Mean nitrate-nitrogen levels ranged from 54±7 to 196±10mg/L at steady state, and the concentration of nitrogenous compounds and organic matter were all positively correlated to feed loading.The TAN loading to the RAS from the specific feed type was assessed in a separate mass-balance study and used as input in a descriptive mathematical model (AQUASIM® software) developed to simulate processes affecting N mass-balances in the RAS. Nitrification kinetic rate constants were applied to the biofilter, and fractions of nitrifiers in suspended solids in the water phase were estimated based on existing information from waste water treatment processes. Two model scenarios successfully simulated the measured TAN concentration in the experimental RAS. The first model scenario applied a first-order area-based nitrification rate (k1a) constant of 0.2m/d, estimating a fraction of active nitrifiers (fN) in the water phase of 4% of the total suspended solids. The second model scenario used a k1a of 0.1, estimating a fN of 8% with similar predictability as in the first scenario. Overall, this study provided new information on fish performance and resulting water quality during steady state RAS operation. Furthermore, the study demonstrated that kinetic modeling can be applied to simulate measured TAN concentrations in experimental RAS.

THE SUSTAINABLE DEVELOPMENT ASSESSMENT OF DRINKING WATER SUPPLY SYSTEM / GERIAMOJO VANDENS TIEKIMO SISTEMOS DARNAUS VYSTYMO VERTINIMAS

Drinking water distribution system takes a significant place in sustainable urban development. In order to solve some environmental issues it is necessary to improve the maintenance of the environmental impact of chemical compounds which can come in contact with water. The aim of the research is to complete the analysis of the sustainable development of drinking water pipelines in Lithuania as well as to structure the chemical content of pipelines for further increase of supplied water quality and simplification of maintenance. Analytical and descriptive methods were used in the research process. The investigation included 150 samples that were obtained in different water stagnation times in lab-scaled pipelines. During the research the following indicators were set: total iron, manganese, ammonium ions, nitrate and nitrite concentrations, turbidity and chemical oxygen demand (CODCr). To ensure sustainability of drinking water distribution system in the end of this research the appliance of a certain model of actions was considered. This model says that material of potable water network must be chosen depending on water chemical indicators, water reaction with pipeline material and scale formation causes. Consequently, to reduce a negative effect of chemical processes on the drinking water supply measures of sustainable ecological development have to be taken. Santrauka Geriamojo vandens tiekimo sistema yra labai svarbus darnios miesto plėtros objektas. Siekiant išspręsti tam tikras aplinkosaugos problemas, būtina padidinti cheminių junginių, kurie gali kontaktuoti su vandeniu, kontrolę, taip užtikrinant tinkamą poveikio aplinkai priežiūrą. Šio mokslinio tyrimo tikslas – atlikti geriamojo vandens vamzdyno Lietuvoje analizę darnaus vystymosi aspektu, struktūrizuoti cheminę vamzdynų sudėtį, siekiant pagerinti tiekiamo vandens kokybę ir supaprastinti tolesnę vandentiekio vamzdynų priežiūrą. Mokslinio darbo metu buvo taikomi analitiniai ir eksperimentiniai tyrimo metodai. Buvo ištirta 150 mėginių, paimtų iš laboratorijoje sukonstruoto vamzdyno. Mėginiai tirti atsižvelgiant į vandens išbuvimo vamzdyne trukmę. Tyrimo metu buvo nustatomi šie cheminiai indikatoriai: bendroji geležis, mangano koncentracija, amonio jonų kiekis, nitritų ir nitratų koncentracijos, drumstumas ir cheminis deguonies suvartojimas (ChDSCr). Siekiant užtikrinti geriamojo vandens tiekimo sistemos tvarumą, tyrimo pabaigoje buvo pasiūlytas tam tikras veiksmų modelis. Jis rodo, kad vandentiekio vamzdynų medžiaga turi būti parinkta pagal tiekiamo vandens cheminius indikatorius, vandens sąveikos su vamzdyno medžiaga ir nuosėdų formavimosi priežastis. Todėl būtina imtis darnaus vystymo priemonių, mažinant neigiamą cheminių procesų įtaką tiekiamo vandens kokybei.

The effect of interferon γ on endothelial cell nitric oxide production and apoptosis

Background:Nitric oxide (NO) is an important molecule in maintaining endothelial survival and normal function. It is a unique mediator, which may promote or suppress both inflammation and apoptosis. Endothelial cell (EC) injury, dysfunction, and death in response to cytokines, especially interferon gamma (IFN-γ), represent the critical event for the initiation of several inflammatory diseases.Objective(s):EC injury or death result in endothelial dysfunction that precedes the development of atherosclerosis and its subsequent vascular events. We examine the effect of different concentrations of IFN-γ on human umbilical vein ECs (HUVECs) NO production and apoptosis.Materials and Methods:HUVECs were cultured at 37°C for 24 h in the absence (control) or presence of 10, 100, and 1000 μg IFN-γ, respectively. The apoptotic cells were determined as annexin V-positive propidium iodide (PI)-negative cells by flow cytometry. Total nitrite concentration was measured in cell cultures supernatant by Griess method.Results:A comparison of the effect of IFN-γ on EC NO production with untreated cells showed that pretreatment of HUVEC with IFN-γ failed to have a significant effect on NO production by these cells at 10 and 100 U/mL, whereas it led to a significant decreased NO production at 1000 U/mL (P < 0.05). The cells stimulated with IFN-γ showed significantly higher apoptotic cells (PI negative and annexin V-positive cells) after 24 h, compared with cells with no stimulations (P < 0.05).Conclusion:IFN-γ has detrimental effects on ECs in high doses. This might be due to inducible NO synthase activation.

Nitrous stress and soluble differentiation molecules in exacerbation of chronic obstructive pulmonary disease

Summary. The aim of this study was to investigate nitrite blood levels (NO2 –) and the total nitrite and nitrate concentration (Σ NO2 – / NO3 –) in the exhaled breath condensate (EBC) and to evaluate interrelationships between NO metabolites and serum sCD50, sCD54, sHLA-I, sCD95 soluble differentiation molecules in patients with exacerbation of chronic obstructive pulmonary disease (COPD). We examined 110 patients with exacerbation of COPD stages I–III and 28 healthy non-smokers. Exacerbation of COPD stages II and III was found to be related to a significant increase in NO2 level in the blood and (Σ NO2 – / NO3 –) in EBC, increased concentrations of sCD50, sCD54, sHLA-I molecules and decreased concentration of sCD95 molecules. Statistically significant strong relationships were found between nitrous stress parameters and serum concentrations of soluble differentiation molecules in exacerbation of COPD. These data could indicate a role of soluble sCD50, sCD54, sHLA-I, sCD95 molecules and nitrous stress in the pathogenesis of COPD progression. These biomarkers could be used as predictors of poor prognosis of early-stage COPD and as diagnostic criteria of exacerbation of COPD stages II–III.

Changes in nitric oxide metabolism in co-morbidity of chronic obstructive pulmonary disease and chronic cerebral ischemia

Summary. The study was aimed at investigation of nitric oxide (NO) metabolism including total and separate concentrations of stable NO metabolites (nitrate anions and nitrite anions) and 3-nitrotirosine concentration in stable chronic obstructive pulmonary disease (COPD) and in COPD with concomitant chronic cerebral ischemia (CCI). The study involved 55 patients aged 51 to 67 years divided into 2 groups: 28 patients with COPD II–III stage (the 1st group) and 27 patients with COPD II–III stage and concomitant CCI II–III stage (the 2nd group). The control group included 25 healthy non-smoking volunteers. A significant increase in nitrate anion concentration and in the total nitrite and nitrate concentration was found in the blood of patients of both groups compared to the controls. A statistically significant inverse relationship was found between the blood nitrite anion concentration and FEV1 (r = –0.77; p &lt; 0.05) in COPD patients. These results demonstrate that changes in NO metabolism related to nitrous stress could emerge even in stable COPD. In co-existing COPD and CCI, changes in these biomarkers could be also related to functional particularities of nitrite reductase apart from the nitrous stress.

Effect of pH and nitrite concentration on nitrite oxidation rate

The effect of pH and nitrite concentration on the activity of the nitrite oxidizing bacteria (NOB) in an activated sludge reactor has been determined by means of laboratory batch experiments based on respirometric techniques. The bacterial activity was measured at different pH and at different total nitrite concentrations (TNO2). The experimental results showed that the nitrite oxidation rate (NOR) depends on the TNO2 concentration independently of the free nitrous acid (FNA) concentration, so FNA cannot be considered as the real substrate for NOB. NOB were strongly affected by low pH values (no activity was detected at pH 6.5) but no inhibition was observed at high pH values (activity was nearly the same for the pH range 7.5–9.95). A kinetic expression for nitrite oxidation process including switch functions to model the effect of TNO2 concentration and pH inhibition is proposed. Substrate half saturation constant and pH inhibition constants have been obtained.

Nitric oxide metabolites status in calves with acute and chronic diarrhea

Neonatal diarrhea in calves causes intestinal inflammation that can lead to an increase in the concentration of some inflammatory mediators like nitric oxide in serum. In the presence of some molecules in biological fluids, nitric oxide sustains a series of reactions and produces nitrate and nitrite. Consequently, this paper has been done to determine if the serum levels of nitrite and nitrate can be a precise yardstick to evaluate the health condition of calves. Sixty calves in three groups (20 heads healthy as control group, 20 heads with chronic diarrhea, and 20 heads with acute diarrhea) were considered, and blood samples were collected to determine the concentration of nitrite and nitrate in serum by reducing by cadmium and evaluation of photo-absorbance by spectrophotometer. Results showed that in calves with acute diarrhea, the total concentration of nitrite and nitrate and the concentration of nitrate were significantly more than healthy calves and the calves with chronic diarrhea (P < 0.001). In addition, a negative and significant correlation (r = −0.788, P value = 0.0353) was observed between nitrite and nitrate concentration of healthy calves.

The Effect of Magnesium Sulfate on Bleeding Time and Nitric Oxide Production in Preeclamsia

Preeclampsia is a disease regarding with altered vascular reactivity leading to hypertension of the mother and metabolic alterations in the fetus. This study aimed to assess nitric oxide and bleeding time following administration of magnesium sulfate to preeclamtic patients compared to normotensive pregnant women. A total of 112 subjects (56 preeclamtic patients and 56 normotensive pregnant controls) were enrolled in this case-control study. Cases and controls were matched for age, BMI, gestational age, parity and gravidity. Total concentration of nitrite and nitrate (NOx) was measured before and during magnesium sulfate (MgSO4) treatment using a modified Griess-based method. Systolic and diastolic blood pressures were significantly decreased during MgSO4 treatment in preeclamtic patients (p < 0.0001). NOx levels were significantly increased in preeclamtic women after MgSO4 administration (33.7 +/- 18.5 vs. 50.2 +/- 21.6, p < 0.0001) but it was not seen in normotensive parturients (52.4 +/- 28.9 vs. 57.3 +/- 21.7, p = 0.362). The bleeding time was scarcely increased following magnesium sulfate treatment in preeclamptic patients compared to normotensive pregnant women but it was not significant (p = 0.18). In addition, there was only a significantly reverse correlation between NOx levels and systolic or diastolic blood pressure in preeclamtic parturients after MgSO4 treatment (r = -0384; p = 0.003 and r = -0.29; p = 0.03, respectively). This study demonstrates that administrating MgSO4 to preeclamtic patients induced significant changes in NOx production which had a major role in modulating vasculature changes in preeclamsia.

Electroacupuncture Zusanli (ST36) on Release of Nitric Oxide in the Gracile Nucleus and Improvement of Sensory Neuropathies in Zucker Diabetic Fatty Rats

The purpose of these studies was to examine the effects of electroacupuncture (EA) Zusanli (ST36) on release of nitric oxide (NO) in the gracile nucleus (GN) and determine if functional neuropathic changes were modified by EA ST36-induced NO in the nucleus in Zucker diabetic fatty (ZDF) rats. The foot withdrawal responses to mechanical, thermal and cold stimuli were measured before and after EA stimulation. A microdialysis probe was implanted in the GN and dialysate samples were collected 20 min before, during and after EA ST36. Total nitrate and nitrite (NOx −) concentrations in the samples were quantified by using chemiluminescence. The baseline dialysate NOx − concentrations in the GN were decreased in ZDF rats compared to lean control (LC) rats (P < .05). In ZDF rats, dialysate NOx − releases in the GN were markedly increased during EA ST36, whereas in LC rats, the releases were moderately enhanced at 20–40 min after EA ST36. The withdrawal latencies to mechanical, cold and thermal stimuli were significantly improved 20 min after EA ST36 both in LC and ZDF rats, but not altered by non-acupoint stimulation. The withdrawal latencies to EA ST36 were further potentiated by 3-morpholinyl-sydnoneimine and inhibited by NG-Propyl-l-arginine infused into the GN in ZDF rats (P < .05). These results show that EA ST36 increases NO release in the GN, and NO in the nucleus modifies withdrawal latencies to mechanical, cold, and thermal nociception stimuli. Data suggest that EA ST36 induces NO release in the GN, which contributes to improvement of sensory neuropathies in rats.

Peroxisome Proliferator-Activated Receptor-γ (PPAR-γ) Activation Confers Functional Neuroprotection in Global Ischemia

The neuroprotective effect of rosiglitazone, a peroxisome proliferator-activated receptor γ (PPARγ) agonist, has been investigated using both in vivo and in vitro models of global ischemia in CD1 mice. Behavioral tests were carried out prior to and at various times (up to 14days) subsequent to bilateral common carotid artery occlusion followed by reperfusion. Mice at each time point were euthanized under anesthesia and the brain was removed, serially sliced and stained with 1% triphenyltetrazolium (TTC) to quantify infarct size. Administration of rosiglitazone (5 or 10mg/kg, i.p.) 10min prior to occlusion significantly reduced the postsurgical mortality rate (10-11 vs. 36%, P<0.05). The higher dose of rosiglitazone (10mg/kg) also significantly reduced the mean area of brain infarct at 1, 3, 7 and 14days post-ischemia, reduced post-occlusion deficits in limb grasping and forelimb placing at various time points, and reduced total nitrite concentration in serum and brain homogenate at day 7 post-occlusion. To model global ischemia in vitro, coronal brain slices were incubated in oxygenated artificial cerebrospinal fluid (ACSF) in the presence of either glutamate (1mM) or hydrogen peroxide (H(2)O(2)) (5μM) for 30min. Both H(2)O(2) and glutamate caused significant tissue damage, and co-incubation with rosiglitazone (5μM) significantly reduced H(2)O(2)-induced damage but did not significantly reduce glutamate-induced brain damage in this model. Our observations provide further evidence for a neuroprotective effect of rosiglitazone in rodent models of ischemia.

Time Course Changes of Oxidative Stress Markers in a Rat Experimental Glaucoma Model

To evaluate the relationship between oxidative stress markers and increased intraocular pressure in experimental glaucoma. In vivo chemiluminescence (CL), total antioxidant capacity (TRAP), nitrite concentration (NC), and lipid peroxidation markers (TBARS) were evaluated. Wistar rats (n=18 for each time point) underwent operation, and two episcleral veins were cauterized. Decreases of 22%, 35%, and 27% at 7, 15, and 30 days and an increase of 22% at 60 days in CL were observed in glaucomatous eyes. In optic nerve, TBARS values were 6.9+/-0.5 nmol/mg protein (7 days), 9.4+/-0.4 nmol/mg protein (15 days), 18.0+/-1.2 nmol/mg protein (30 days), and 43.1+/-5.3 nmol/mg protein (60 days) (control, 6.2+/-0.4 nmol/mg protein; P<0.001). NC was 37.0+/-1.8 microM (7 days), 31.4+/-1.2 microM (15 days), 39.6+/-1.3 microM (30 days), and 40.0+/-1.3 microM (60 days) (control, 21.1+/-1.7 microM; P<0.001). In glaucomatous vitreous humor, TRAP decreased by 42% at 15 days and 78% at 60 days (control, 414+/-29 microM; P<0.001). In glaucomatous aqueous humor, TRAP values were 75+/-7 microM (7 days), 54+/-4 microM (15 days), 25+/-4 microM (30 days), and 50+/-3 microM (60 days) (control, 90+/-10 microM; P<0.001). Reactive species were increased in glaucoma, as evidenced by the increases in CL, TBARS, and NC. The decrease in the antioxidant levels may be a consequence of an increase in oxidative processes.

Effect of urate on nitric oxide microcirculatory response in the rat tail to body heating.

The objective of this study was to determine if nitric oxide (NO)-mediated cutaneous vasodilation depends on urate concentrations. Capillary blood cell velocities (BCV) in the tail capillary vessels of anesthetized, heat-stressed Sprague-Dawley rats were measured by the videomicroscopy method, and the femoral mean arterial pressure (MAP) was recorded on a Grass polygraph. The effects of urate or urate and NO production on the above parameters were determined by using specific inhibitors of these compounds, for example, allopurinol (All) or All or N-nitro-L-arginine (NNA), respectively. Urate concentrations were determined by an enzymatic, colorimetric method, and total nitrite levels were measured fluorometrically. During heat stress, All or All and NNA significantly decreased plasma urate or urate and total nitrite concentrations, respectively, and the response of vascular conductance (estimated as a ratio of BCV to MAP). Urate administration, after All and NNA pretreatment, restored plasma urate and total nitrite concentrations and increased BCV/MAP. Urate at physiological concentration helps to maintain vascular conductance of cutaneous capillaries in the rat tail during body heating. The effect of urate on vascular conductance may be mediated by NO.

Operational Boundaries for Nitrite Accumulation in Nitrification Based on Minimum/Maximum Substrate Concentrations That Include Effects of Oxygen Limitation, pH, and Free Ammonia and Free Nitrous Acid Inhibition

Recent studies on shortcut biological nitrogen removal (SBNR), which use the concept of denitrification from nitrite, have reported the key factors affecting nitrite build-up, such as dissolved oxygen (DO) limitation, pH, and free ammonia (FA) and free nitrous acid (FNA) inhibition. This study extends the concept of the traditional minimum substrate concentration (S(min)) to explain the simultaneous effect of those factors. Thus, we introduce the minimum DO concentration (DO(min)) and the maximum substrate concentration (S(max)) that are needed to support a steady-state biological system. We define all three values as the MSC values. The model provides a method to identify good combinations of pH, DO, and total ammonium nitrogen (TAN) to support shortcut nitritation. We use MSC curves to show that the effect of DO-alone and the effect of DO plus direct pH inhibition cannot give strong enough selection against nitrite oxidizing bacteria to work in a practical setting. However, adding the FA and FNA effects gives a strong selection effect that is accentuated near pH 8. Thus, a generalized conclusion is that having pH approximately 8 is favorable in many situations. We defined a specific operational boundary to achieve shortcut nitritation coupled to anaerobic ammonium oxidation (ANAMMOX), in which the effluent concentrations of total nitrite and total ammonium should be approximately equal. Experimental results for alkaline and acidic nitrite-accumulating systems match the trends from the MSC approach. In particular, acidic systems had to maintain higher total ammonium, total nitrite, and DO concentrations. The MSC values are a practical tool to define the operational boundaries for selecting ammonium-oxidizing bacteria while suppressing nitrite-oxidizing bacteria.

Seasonality in expression and distribution of nitric oxide synthase isoforms in the testis of the catfish, Clarias batrachus: Role of nitric oxide in testosterone production

Nitric oxide (NO) is a well-recognized versatile signaling molecule. It is produced by catalytic action of nitric oxide synthase (NOS) on L-arginine in a variety of animal tissues. Existence of different isoforms of NOS has been shown in mammalian testis, but report on their presence in the testis of ectothermic vertebrates is non-existent. This study demonstrates the differential expressions of two isoforms of nitric oxide synthase (neuronal-nNOS and inducible-iNOS) like molecules in different cell types in the testis of seasonally breeding catfish, Clarias batrachus through immunohistochemistry. Positive immunoprecipitation of nNOS and iNOS like molecules were detected in germ cells as well as interstitial cells only in the recrudescing and fully mature fish. The immunoreactions differed in intensity and varied with changing reproductive status. Treatment of adult male fish with NO donor, sodium nitroprusside, and a NOS inhibitor, N-nitro-L-arginine methyl ester (L-NAME) increased and decreased the total nitrate and nitrite concentration in the testis, respectively. Sodium nitroprusside and L-NAME also induced simultaneous decline and rise in the testicular testosterone level, respectively. These findings, thus, suggest that NOS isoforms are expressed variedly in different cell types in the testis of reproductively active fish. This investigation also suggests that NO inhibits testosterone production in the testis.

Electrochemical oxidation process for water condensates recycling in a shuttle orbiter

A pilot plant has been built for the regeneration of humidity condensates during shuttle missions. The plant is an automated experimental apparatus which includes an electrochemical cell, two reservoirs and a control system to maintain the temperature within a chosen range, so that the ionic exchange membranes are not damaged. The electrodes used to determine catalytic efficiency were: platinised titanium with ruthenium oxide and Sb and Sn coatings deposited on a Ti substrate, prepared with two different techniques, spray/brush coating and electro-deposition. The Ti/SnO2–Sb2O5 coating was characterized through the following techniques: X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersion spectroscopy (EDS) and linear and cyclic voltammetry (CV). Among the different contaminant dissolved in the contaminant solution, urea was chosen to carry out the electrochemical tests. Several regenerative treatment runs were performed with the solution simulating the shuttle condensate water to determine the evolution, during the tests, of the total organic carbon (TOC) concentration, the nitrate and nitrite concentrations, the ammonia concentration, the pH and the conductivity. These runs were carried out at different current intensities to understand the influence of the anodic current on the organic decomposition rates, in particular of the urea in presence of an amount of sodium chloride. The contaminant removal efficiencies in the electro-oxidation test appeared to be depressed for both electrodes at high current density, whereas the inversion of the electrode polarity seemed to offer a further advantage. The best result reached in the direct electro-oxidation was the 24 ppm as TOC with Ti/SnO2–Sb2O5 at 0.2 A. This value is far from the limit concentration (0.5 ppm), which is the standard level for drinking water in space appliances. During the tests, a decrease in the pH was observed, due to the formation of refractory substances such as organic acids.

Reproductive responses and nitric oxide activity in Japanese quail, Coturnix coturnix japonica, are altered by specific phase relationships of neural (serotonergic and dopaminergic) oscillations and pineal function

The present study investigates the effects of temporal synergism of 5-hydroxytryptophan (5-HTP) and l-dihydroxyphenylalanine ( l-DOPA) and pineal function (pinealectomy and melatonin administration) on gonadal response and nitric oxide (NO) activity in Japanese quail. Three-week-old male quails were divided into 9 groups, as follows: (I) control (treated with normal saline); (II) 8-h and (III) 12-h (receiving l-DOPA after the administration of 5-HTP [5 mg/100 g body weight] at the interval of 8 and 12 h, respectively, over a period of 13 days); (IV) SO (sham operated); (V) Px (pinealectomized); (VI) Veh (vehicle treated control); (VII) Mel (melatonin 25 μg/100 g body weight for 45 days); (VIII) 12-h + Veh; and (IX) 12-h + Mel (same as in (III) but further treated with the vehicle or melatonin, respectively, for 32 days). Body weight and cloacal gland volume were recorded weekly, whereas spermatogenesis, plasma testosterone concentration, and total nitrite and nitrate concentration in plasma, hypothalamus, and testes were measured at the termination of the study. Results indicate that compared to the controls, 8-h, Mel, and 12-h + Mel treatments suppressed whereas 12-h and Px stimulated the reproductive system. Further, a significant increase in plasma testosterone, total nitrite, and nitrate in the 12-h and Px groups and a decrease in these concentrations in 8-h, Mel and 12-h + Mel quail were observed. It is evident that 5-HTP and l-DOPA given at the interval of 8 h, as well as melatonin, are potent inhibitors of gonadal development, and the gonado stimulatory effect of the 12-h temporal relationship of the neurotransmitter precursors is masked by the inhibitory effect of melatonin. It is concluded that modulation of the daily phase relationship of neural oscillations and pineal function alters gonadal function and NO activity. Further, NO exhibits a parallel relationship with gonadal function in Japanese quail; this relationship appears to be mediated through NO activity, suggesting a causal relationship, although the mechanism between the 2 systems remains a topic of discussion.