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PubMed1998

Chronic exposure to ozone and nitric acid vapor results in increased levels of rat pulmonary putrescine.

In the past decade, there has been growing public concern for the human health effects of exposure to environmental pollutants. Ozone (O3) is one of the most reactive components of photochemical air pollution. Despite extensive investigations by many laboratories on the functional, biochemical, and cellular effects of O3 exposure in humans, animals, and in vitro systems, questions remain concerning the potential adverse effects to human health represented by chronic near-ambient exposure to this environmental pollutant. In the present investigation, the influence of inhalation of O3 and nitric acid (HNO3) vapor on polyamine levels was examined in rat lungs. Male F344/N rats were exposed nose-only to 0.15 ppm O3 and 50 microg/m3 HNO3 vapor alone and in combination for 4 hours/day. 3 days/week for a total of 40 weeks. At this time the animals were sacrificed and their lungs were examined for polyamine contents. Exposure to O3 and O3 plus HNO3 vapor caused a significant increase in the putrescine content of the lung compared to the air-exposed controls (P < 0.05). The concentrations of pulmonary spermidine and spermine were not significantly increased by exposure to either O3 or HNO3 vapor alone or in combination compared to the air-exposed controls. The role of polyamines in repair and anti-inflammatory processes has been discussed.

Air Pollutants↗
PubMed2001

Preliminary measurements of summer nitric acid and ammonia concentrations in the Lake Tahoe Basin air-shed: implications for dry deposition of atmospheric nitrogen.

Over the past 50 years, Lake Tahoe, an alpine lake located in the Sierra Nevada mountains on the border between California and Nevada, has seen a decline in water clarity. With significant urbanization within its borders and major urban areas 130 km upwind of the prevailing synoptic airflow, it is believed the Lake Tahoe Basin is receiving substantial nitrogen (N) input via atmospheric deposition during summer and fall. We present preliminary inferential flux estimates to both lake surface and forest canopy based on empirical measurements of ambient nitric acid (HNO3), ammonia (NH3), and ammonium nitrate (NH4NO3) concentrations, in an effort to identify the major contributors to and ranges of atmospheric dry N deposition to the Lake Tahoe Basin. Total flux from dry deposition ranges from 1.2 to 8.6 kg N ha-1 for the summer and fall dry season and is significantly higher than wet deposition, which ranges from 1.7 to 2.9 kg N ha-1 year-1. These preliminary results suggest that dry deposition of HNO3 is the major source of atmospheric N deposition for the Lake Tahoe Basin, and that overall N deposition is similar in magnitude to deposition reported for sites exposed to moderate N pollution in the southern California mountains.

Air Pollutants↗
PubMed1996

Chronic inhalation exposure to ozone and nitric acid elevates stress-inducible heat shock protein 70 in the rat lung.

The ability of urban oxidant and acid air pollutants to induce heat shock proteins (HSPs) in the mammalian lung is not known. Such proteins are known to be correlated with environmental stress and pathophysiological conditions. In this study, stress-inducible HSP 70 was assessed by slot-blotting in rat lungs (N=10 per group) following inhalation exposures for 4 h per day, 3 days per week for 40 weeks to the following pollutants: (a) purified air;(b) 0.15 ppm ozone (O3);(c)50 micrograms/m3 nitric acid (HNO3); or(d) a combination of both 0.15 ppm O3 and 50 micrograms/m3 HNO3. At 24 h following the last exposure, samples from the right apical lobe of the lung were obtained for either slot-blotting or gel electrophoretic separation, subsequent protein immunoblotting, and chemiluminescence detection of HSP 70 levels. Experiments demonstrate that stress-inducible HSP 70 was present constitutively in the control lungs and was separable from the constitutive form of HSP 70. Slot-blotting analysis demonstrate that the O3 and HNO3 exposures alone produced significant elevations of HSP70. Specifically, either O3 or HNO3 alone significantly elevated lung stress-inducible HSP 70 levels by 277% and 221% respectively, above control levels. The group exposed to combined O3 and HNO3 showed a 177% elevation in lung stress-inducible HSP 70 that was significantly greater that the group inhaling purified air, but this effect was less than the effects of either pollutant component alone. Moreover, all exposure groups were significantly different from one another. These results indicate that stress-inducible HSP 70 in the rat lung is highly elevated after chronic inhalation exposures to both O3 and HNO3 when administered either alone or in combination within the range of urban ambient concentrations.

Administration, Inhalation↗
PubMed1993

Bronchopulmonary actions of 1-(1,2,3,4-tetrahydro-1-naphthylenyl)-1H-imidazole, nitric acid salt (LY150310), a substituted imidazole, in the guinea pig.

1-(1,2,3,4-tetrahydro-1-naphthylenyl)-1H-imidazole, nitric acid salt (LY150310), was examined for bronchodilator activity in the guinea pig. In guinea pig tracheal preparations, LY150310 competitively antagonized the contractile effects of exogenous histamine and blocked the histamine-mediated component of contractions produced by ovalbumin challenge. LY150310 had little effect on the nonhistamine component of ovalbumin-induced contractions of lung parenchymal strips, but it enhanced the production of prostaglandin (PG) E2 and PGF2 alpha although it partially inhibited thromboxane B2 formation. In other studies, in which postmortem pulmonary gas trapping was used as an index of in vivo airway obstruction, i.v. LY150310 dose-dependently inhibited the bronchospasm produced by aerosols of the divalent cationic ionophore A23187, histamine, 5-hydroxytryptamine, leukotriene D4, methacholine, ovalbumin or platelet activating factor. LY150310 was equal to or more potent than aminophylline in all test systems. Also, orally administered LY150310 inhibited the airway obstruction produced by selected challenge aerosols. In ex vivo studies, LY150310 elevated PGE2 and tended to decrease thromboxane B2 in sodium arachidonate-stimulated whole blood. However, PGE2 and other cyclooxygenase products did not appear to account for in vivo bronchodilation, because combining LY150310 and piroxicam did not alter inhibition of A23187-induced airway obstruction. Our results demonstrate that LY150310 reduces airway obstruction caused by a variety of bronchoconstrictive agents, including A23187 and ovalbumin. Although this substituted imidazole appears to have activity as a histamine H1-receptor antagonist and can alter prostanoid concentrations in vitro and in vivo, its mode of bronchodilation is unclear.

Aerosols↗
PubMed2001

An analysis of excitatory amino acids, nitric oxide, and prostaglandin E2 in the cerebrospinal fluid of pregnant women: the effect on labor pain.

UNLABELLED: It is still unclear which neurotransmitters are involved in labor pain. We measured the concentrations of excitatory amino acids, nitric oxide, and prostaglandin E2 in the cerebrospinal fluid (CSF) of pregnant women, particularly in those with labor pain. The patients included in the study consisted of women who underwent cesarean delivery either with labor pain (Labor Pain group, n = 40) or without labor pain (Nonlabor Pain group, n = 58). All patients received spinal anesthesia (intrathecal injection of 10-12 mg of bupivacaine) for the operation, and 2 mL of CSF was collected before bupivacaine injection. Concentrations of aspartate and glutamate (0.50 +/- 0.06 microM and 0.79 +/- 0.10 microM, respectively) were significantly larger in the Labor Pain group than in the Nonlabor Pain group (0.35 +/- 0.03 microM and 0.54 +/- 0.04 microM, P < 0.05). There were no significant differences in the concentrations of nitric oxide and prostaglandin E2 between the groups. A positive correlation was found between CSF concentrations of excitatory amino acids and labor pain. IMPLICATIONS: The excitatory amino acids, aspartate and glutamate, play a role in labor pain. N-methyl-D-aspartate receptor antagonists may be useful for labor pain and postlabor uterine contraction pain relief.

Adult↗
PubMed2004

Evidence that nitric acid increases relative humidity in low-temperature cirrus clouds.

In situ measurements of the relative humidity with respect to ice (RHi) and of nitric acid (HNO3) were made in both natural and contrail cirrus clouds in the upper troposphere. At temperatures lower than 202 kelvin, RHi values show a sharp increase to average values of over 130% in both cloud types. These enhanced RHi values are attributed to the presence of a new class of HNO3-containing ice particles (Delta-ice). We propose that surface HNO3 molecules prevent the ice/vapor system from reaching equilibrium by a mechanism similar to that of freezing point depression by antifreeze proteins. Delta-ice represents a new link between global climate and natural and anthropogenic nitrogen oxide emissions. Including Delta-ice in climate models will alter simulated cirrus properties and the distribution of upper tropospheric water vapor.

Journal Article↗
PubMed2001

Kinetics of hydrazinium nitrate decomposition in nitric acid solutions under the effect of power ultrasound.

The effect of ultrasound (f = 20 kHz) on the decomposition of hydrazinium nitrate was investigated in a nitric acid medium. The kinetics of N2H5+ decomposition and initial HN3 formation increase in a linear manner with the HNO3 concentration (from 1 to 6 M) and with the ultrasonic intensity (from 0.5 to 3.1 W cm-2). Both rates were equal to that of HNO2 formation in the absence of N2H5+, indicating that the N2H5+ decomposition mechanism is the same as observed without ultrasound between HNO2 and N2H5+. The variation of the steady-state HN3 concentration with the HNO3 concentration and the ultrasonic intensity suggests the existence of a nonexplosive HN3 thermal decomposition mechanism in the cavitation bubble under the effect of ultrasound. It was also observed at ultrasonic intensities exceeding 3.5 W cm-2 that the decomposition of HN3 led to the accumulation of NH4+ in solution.

Journal Article↗
PubMed2004

Removal of metals from industrial sludge by extraction with different acids.

This study addresses the feasibility of removing Cu and Ni from sludges of printed circuit board (PCB) plants by acidic extraction. Citric acid, acetic acid, hydrochloric acid, nitric acid, and sulfuric acid at various concentrations were experimentally examined to determine preferred conditions for removing Cu and Ni. Experimental results indicate that the removal ratios of Cu were 57% (citric acid), 79% (acetic acid), 81% (hydrochloric acid), 91% (nitric acid), and 92% (sulfuric acid), and that of Ni was 74% (citric acid), 70% (acetic acid), 75% (hydrochloric acid), 92% (nitric acid), and 93% (sulfuric acid), using 1 N extractants. The removal ratios obtained using sulfuric acid or nitric acid at a particular concentration were in the order Pb> Ni> Cu> Zn. The kinetic extraction results revealed that the extraction of Cu and Ni by nitric acid and sulfuric acid exhibited a lagphase after 60min and the removal ratio was then around 90%. The kinetic results also revealed that the extraction rate constants of Cu and Ni increased with the concentration of the acid. The extraction rate constants of Cu and Ni followed the order sulfuric acid > nitric acid > acetic acid, and it also showed that Ni was more easily extracted than Cu from PCB sludge. The total percentages of Cu extracted by 1 N acetic acid, nitric acid, and sulfuric acid, determined in three replicate extractions were 78, 94, and 94%, and those of Ni were 89, 94, and 98%, respectively. The residue sludge, following three replicate extractions using 1 N acetic acid, nitric acid, and sulfuric acid, was further tested by toxicity characteristic leaching procedures (TCLP), and more than 15 mg/L of Cu was leached, exceeding the legal concentration in Taiwan. This observation reveals that the residue sludge following three replicate extractions by acids remained hazardous waste. Further treatment, such as solidification, must be performed before the sludge is disposed of.

Acids↗
PubMed1976

The effect of graded 60 degrees C 1N nitric acid extraction and of deoxyribonuclease digestion on nuclear staining by metachrome mordant dye metal salt mixtures.

We can divide metachrome mordant staining of nuclei after graded 60 degrees C 1 N nitric acid extraction into three groups. The Feulgen nucleal reaction and dilute cationic dye staining of nuclei are abolished in about 30 minutes. With one group of metachrome dyes nuclear staining is lost with acid exposures of one hour or less. In a second group nuclear staining is weakened by 30-60 minute extractions, but persists in recognizable grade for 4-6 hours. In the third group nuclear staining remains almost unimpaired for 4-6 hours. In the first group the nuclear staining seems clearly assignable to the nucleic acids and to DNA in particular. In the second group loss of part of the reactivity on short exposure indicates some participation of DNA in the control staining result, as well as participation of basic nucleoprotein. In the third group staining seems assignable largely to basic nucleoprotein. The five gallocyanin group dyes, all in group 1, all possess a dialkylamino group, probably functioning as an ammonium chloride.Hematoxylin, the flurone blacks and gallein all present an o-hydroxysemiquinone group which probably acts as a weak acid, in addition to the carboxyl group of gallein which gives the strongest staining of nuclei at the longest acid exposure. Deoxyribonuclease digestion (2 hours, 37 degrees C) separated sharply a class in which nuclear staining failed completely, a class in which nuclear staining was fully equal to that in the control preparations and an intermediate group in which slight, moderate, or severa impairment was present. Generally there was good agreement between the two methods of nucleic acid removal, despite the fixation difference. In each case, however, the extraction procedure was one worked out for the fixation on which it was used.

Alum Compounds↗
PubMed2006

Hydrogen-bonded complexes of nitrous and nitric acids with ethene Ab initio and DFT studies.

The complexes formed by ethene with nitric and nitrous (trans and cis) acids have been investigated by ab initio (SCF and MP2) and B3LYP calculations with 6-311++G(d,p) basis set. Full geometry optimisation has been performed for the complexes studied. The most stable structures of the complexes are established. Bearing in mind the corrected values of the dissociation energy the studied hydrogen-bonded complexes can be ordered as follows: C(2)H(4)...HONO(2)>C(2)H(4)...HONO-trans>C(2)H(4)...HONO-cis. In the complexes the acids act as proton donors forming the pi-type of hydrogen bond with ethene. The predicted changes in the vibrational characteristics (vibrational frequencies and infrared intensities) arising from the hydrogen bonding are in good agreement with the experimentally measured. The predicted frequency shift of the stretching OH vibration in the nitric acid is largest (-210 cm(-1)), followed by the shifts in the trans-HONO (-141 cm(-1)) and cis-HONO (-109 cm(-1)). The calculations predict an increase of the IR intensity of the stretching O-H vibration in the complexes from 6 to 10 times.

Ethylenes↗
PubMed2005

Formation of nitric acid in the gas-phase HO2 + NO reaction: effects of temperature and water vapor.

A high-pressure turbulent flow reactor coupled with a chemical ionization mass spectrometer was used to investigate the minor channel (1b) producing nitric acid, HNO3, in the HO2 + NO reaction for which only one channel (1a) is known so far: HO2 + NO --> OH + NO2 (1a), HO2 + NO --> HNO3 (1b). The reaction has been investigated in the temperature range 223-298 K at a pressure of 200 Torr of N2 carrier gas. The influence of water vapor has been studied at 298 K. The branching ratio, k1b/k1a, was found to increase from (0.18(+0.04/-0.06))% at 298 K to (0.87(+0.05/-0.08))% at 223 K, corresponding to k1b = (1.6 +/- 0.5) x 10(-14) and (10.4 +/- 1.7) x 10(-14) cm3 molecule(-1) s(-1), respectively at 298 and 223 K. The data could be fitted by the Arrhenius expression k1b = 6.4 x 10(-17) exp((1644 +/- 76)/T) cm3 molecule(-1) s(-1) at T = 223-298 K. The yield of HNO3 was found to increase in the presence of water vapor (by 90% at about 3 Torr of H2O). Implications of the obtained results for atmospheric radicals chemistry and chemical amplifiers used to measure peroxy radicals are discussed. The results show in particular that reaction 1b can be a significant loss process for the HO(x) (OH, HO2) radicals in the upper troposphere.

Journal Article↗
PubMed1998

Nitrate tolerance is specific for nitric acid esters and its recovery requires an intact protein synthesis.

Using cultured LLC-PK1 cells the present study investigates mechanisms leading to nitrate tolerance and its reversal. A 5-h pretreatment with glyceryl trinitrate (GTN, 0.01-100 microM) resulted in desensitization of the intracellular cyclic GMP response to a subsequent 10-min challenge with GTN (1 microM). The spontaneous donor of nitric oxide (NO) spermine NONOate, which releases NO independently of enzymatic catalysis, did not induce tolerance to its own cyclic GMP stimulatory effect and remained fully effective in GTN-tolerant cells. Tolerant cells regained sensitivity to GTN after a 30-h incubation in media. Recovery of the cyclic GMP response was blocked in the presence of cycloheximide (10 microM) suggesting that de novo protein synthesis is necessary for tolerance reversal. Our results demonstrate that nitrate tolerance is specific for nitric acid esters and possibly due to down-regulation of enzymes involved in bioactivation of, and NO generation from, organic nitrates.

Animals↗