Urinary nitrite

None of the exposures produced changes in clinical chemistry values (blood count, blood nitrate, blood urea nitrogen, serum enzymes, and serum electrolytes or urinalysis and nitrate and nitrite urinary excretion), spontaneous electrical activity of the cortex of the brain (detected by EEG), pulse rate and sinus rhythm, or pulmonary function. Visual and auditory acuity, exercise EKG, and time estimation tests did not differ from control values for any of the exposures. Only one of several cognitive tests was affected by exposure and the change occurred only in the four subjects exposed at 1.5 ppm. The test was taken during the time the subjects were experiencing severe headaches. 

Color, yellow character, hazy glucose (-) ketones (-) specific gravity 1.020 pH 5.0 (+) protein coarse granular casts, 5 to 10/low-powered field white blood cell (WBC) count, 5 to 10/high-powered field red blood cell (RBC) count, 2 to 5/high-powered field no bacteria nitrite (-) blood small osmolality 325 mOsm urinary sodium 77 mEq/L (77 mmol/L) creatinine 63 mg/dL (5569 pmol/L)... 

Free radicals are supposed to have a significant role in the progression of acute pancreatitis. The involvement of free radicals was firstly demonstrated in many animal models [355,356], Later on, it has been shown that the levels of superoxide and lipid peroxides increased in the blood from patients with acute pancreatitis [357], Rahman et al. [358] found enhanced urinary nitrite excretion in patients with severe acute pacreatitis. It was suggested that this fact is not simply a reflection of systemic inflammation but probably a consequence of the endotoxin-mediated upregulation of inducible NO synthase. 

Children with CD consuming oats have similar reduction in urinary nitrite/nitrate excretion as GFD children yet for some, nitrite/nitrate levels remain high, longterm follow-up needed... 

The first indication that NO is generated in cells came from studies of cultured macrophages, which showed that treatment with inflammatory mediators, such as bacterial endotoxin, resulted in the release of nitrate and nitrite, molecules that can form from the breakdown of NO. Similarly, injection of endotoxin in animals elevated urinary nitrite and nitrate. 

Acetaldehyde is oxidized to acetic acid by NAD+-dependent aldehyde dehydrogenases (ALDH) in liver and nasal mucosal preparations. Its administration to rats causes an increase in urinary excretion of sulfur metabolites and it is known to react with cysteine to produce a thiazolidine 4-carboxylic acid derivative that can be A -nitro-sated in vivo upon co-administration of nitrite (lARC, 1985). Many studies have been published subsequently, but these have been mainly in the context of ethanol metabolism. 

A urine dipstick indicates a urinary glucose of >25 mmol/L but is negative for nitrites and leucocyte esterase. 

The urinary tract is normally sterile and dipsticks or reagent test strips are used to detect bacteriuria (presence of bacteria in the urine) by testing for nitrites (all common UTI bacteria convert nitrate to nitrite) or leucocyte esterase (enzyme indicating the presence of white blood cells). 

Tolerance limits the clinical use of organic nitrite and nitrate esters it is associated with increased angiotensin II (ANGII)-dependent vascular production of superoxide radical from NAD(P)H oxidase and endothelial NOS (eNOS) (25,26). The superoxide radical generated by these enzymes reacts with NO derived from the NO-donor to form peroxynitrite, as indicated by the finding of increased urinary 3-nitrotyrosine in nitrate-tolerant patients (27). Importantly, nitrate tolerance is also associated with cross-tolerance to endothelium-derived NO (28), both by... 

Urine leukocyte esterase (Uv) v and nitrite Does this patient have. a urinary tract infection Positive LE, positive nitrite, or both Send urine to laboratory for microscopy, culture and sensitivity and treat if positive Appropriate use of antibiotics, decreased morbidity... 

Urine LE and nitrite Does this patient have a urinary tract infection Normal dipstick result Do not send urine to laboratory, look for alternative cause of symptoms Inappropriate antibiotic ti eatment avoided, unnecessary laboratory work avoided... 

The presence of leukocyte esterase is indicative of pyuria. The detection of nitrite is indicative of the presence of bacteria that degrade nitrate excreted in the urine. The combination of the two tests is valuable in patients with urinary tract infection. The absence of both constituents is a valuable test to rule out urinary tract infection, thereby reducing the number of samples sent to the laboratory for further tests. The nitrite test may be less helpful in young children in whom the urine remains in the bladder for less time, thereby limiting the time for nitrite production. 

Nitrite is formed by conversion from nitrate by urinary bacteria. The presence of nitrite may indicate that the patient has a urinary tract infection. 

Several biochemical tests have been developed for screening mine for the presence of bacteria. A common dipstick test detects the presence of nitrite in the urine, which is formed by bacteria that rednce nitrate normally present in the urine. False-positive tests are nncommon. False-negative tests are more common and freqnently are cansed by the presence of gram-positive organisms or P. aeruginosa that do not reduce nitrate. Other causes of false tests include low urinary pEf, frequent voiding, and dilute urine. 

The observation that the urinary metabolite of safrole, 3-piperidyl-l-(3, 4 -methylenedioxyphenyl)-l-propanone is mutagenic and is structurally somewhat reminiscent of certain Piper amides, has led to the suggestion that some of these compounds should, perhaps be considered as potential mutagens or carcinogens [141]. Whether or not this proves to be a problem warranting major concern, it is well to note that mono-N-substituted amides can react with nitrite under acidic conditions, with formation of potentially carcinogenic N-nitroso products [131]. 

As with blood, urine analysis is used in clinical studies, and the relative concentrations of various ionic species are of great importance in both disease diagnostic and drug metabolism studies. For example, IC is used to determine urine oxalate concentrations. Urinary oxalate levels are an important parameter in urolithiasis research (kidney stones). Other anions that can be determined in urine using IC include phosphate, sulfate, bromide, citrate, nitrate, nitrite, and thiosulfate. As with blood and serum samples, both ultrafiltration and centrifugation are often used as sample cleanup steps. 

Testing of urine for nitrite is important because it can be used to detect urinary tract infection. The basis of the spot test used in the Nitur-Test (Boehringer Mannheim) and in the Rapignost strip system (Hoechst AG) is the classical Griess test. 

The nitrite test of the Merck Co. detects as little as 10 pg H nitrite. It uses filter paper impregnated with an aqueous solution containing methanol, 1-2 g of a diazotizable amine, 0.1-0.5 g of a coupling component, and 2-8 g of solid organic acid per 100 ml. The paper is dried and cut into strips and is specific for nitrite independent of urinary pH. The test reveals significant bacteriuria when the bacterial count reaches 1 x lO ml of urine. 

Paradoxically, considraing the essential benefits of NO, its overproduction leads to septic shock. Uncontrolled release may also be the cause of brain damage afta- a stroke and disorders such as Alzheimer s and Huntington s diseases. The occurrence of high levels of nitrite ion, NO2 (the product of NO oxidation), in the joints of people with rheumatoid arthritis indicates overproduction of NO as a response to inflammation. Similar associations have been established for schizophrenia, urinary disorders, and multiple sclerosis. The rapidly evolving story of NO is an example of how little we still know about the functions of the body, but also how rapidly a discovery leads to the evolution of an entire field. 

---