Polyneuropathy from inhalation of N2O cartridges through a whipped-cream dispenser.

A generalized toxic polyneuropathy was identified in a 23-year-old woman after excessive intentional inhalation of compressed N2O delivery from cartridges through a whipped-cream dispenser. The chronology of the patient's N2O abuse correlated clearly with two episodes of recurrent polyneuropathy. The toxic effects were limited to the nervous system, primarily involving the peripheral nerves, although some signs suggested a possible effect on the cerebellum or its connections. The findings on sural nerve biopsy were nonspecific, characterized principally by axonal degeneration. Gas chromatographic analysis of the N2O cartridges dispensed through the whipped-cream canister revealed an exposure to N2O and 26 other compounds. Three of these, trichloroethylene, toluene, and phenol, are known neurotoxins.

Synthesis of anthraquinonyl glucosaminosides and studies on the influence of aglycone hydroxyl substitution on superoxide generation, DNA binding, and antimicrobial properties.

A series of anthraquinonyl glucosaminosides (10a-e) were synthesized by Koenigs-Knorr glycosidation of the corresponding aglycones (11a-e) with bromo sugar 12 followed by saponification. These glycosides were intended to serve as models to study the role played by the hydroxyl substituents on the aglycone portion of the antitumor anthracycline antibiotics. Superoxide generation as measured in rat heart sarcosomes was found to increase with the addition of successive hydroxyl groups to the anthraquinone nucleus. The 1,8-dihydroxy pattern was determined to generate significantly less superoxide than the 1,4-dihydroxy pattern. Hydroxyl substitution was also observed to stabilize the complex formed between the anthraquinones and DNA and was required for antibacterial activity against a number of Gram-positive organisms.

Potent mutagenic impurities in a commercial sample of 3-nitro-9-fluorenone.

A commercial sample of 3-nitro-9-fluorenone was a potent mutagen in the Ames Salmonella assay, producing 1000 TA98 net revertants per plate at 0.76 microgram/plate without the presence of liver homogenates (-S9). After purification by high-pressure liquid chromatography (HPLC), 3-nitro-9-fluorenone was found to be at least 6 times less active than the parent sample. The commercial sample was fractionated by HPLC and the mutagenic impurity peaks collected and subjected to high-resolution mass spectrometry (HRMS). The mass spectra of 2 potent mutagenic fractions showed the principal molecular species to be a dinitrofluorenone and an acetamidomononitrofluorenone. Samples of synthetic 2,7-dinitro-9-fluorenone and 2-acetamido-3-nitro-9-fluorenone had mutagenic activities, HPLC retention times, and mass spectra characteristics similar to the mutagenic impurity fractions collected from the commercial sample.

Biophysical and electrophysiological studies of hexanedione neurotoxicity.

This study examined the significance of nerve microviscosity changes which occur in 2,5-hexanedione (2,5-HD) neurotoxicity. To establish a correlation between microviscosity changes and neuronal damage, a standard axonal neuropathy (nerve section) was employed. Electrophysiological studies of the sciatic-tibial nerve of rats were carried out to detect the onset of nerve damage. Also, because 2,5-HD may affect membranes in general, with nerve membranes being the most sensitive, red blood cell ghost membranes were prepared from 2,5-HD treated animals and tested for viscosity changes. Results of these studies suggest that 2,5-HD and nerve section have similar effects on myelin microviscosity.

Manganese neurotoxicity: effects of varying oxygen tension and EDTA on dopamine auto-oxidation.

Manganese (Mn) is an essential trace element which, in excess, induces a chronic parkinsonian disease in animals and humans. Previous work indicated that Mn was more potent than other transition metal ions at stimulating dopamine (DA) auto-oxidation. We incubated Mn and DA at 37 degrees C and observed optical density changes at 480 nm, which is proportional to aminochrome formation. pO2 was held at O(N2), 160(O2), or 720 mm Hg(95%O2). Air without Mn produced approximately the same oxidation rate as Mn under N2; air plus Mn (33 uM) yielded a rate 5-fold greater than either air or Mn alone. Under elevated pO2, Mn (10 uM) produced approximately twice the rate seen with air. Addition of the chelating agent (EDTA, 1 mM) produced an 80% decrease in Mn-stimulated DA auto-oxidation. Results are consistent with a role for activated oxygen metabolites in DA depletion seen in chronic Mn intoxication.

Manganese catalyzed auto-oxidation of dopamine to 6-hydroxydopamine in vitro.

Manganese (Mn) is an essential trace element which, upon excessive exposure, produces a neurological syndrome similar to chronic Parkinson's disease in animals and humans. Previous work demonstrated that Mn was more potent than other transition metals in stimulating dopamine (DA) auto-oxidation. In these experiments, DA was incubated under physiological conditions in the presence and absence of Mn for up to 60 min. 6-Hydroxydopamine (6-OHDA) was produced in the presence of Mn, while the incubation mixture without Mn showed no DA oxidation. 6-Hydroxydopamine is a neurotoxicant which exerts its effects by destroying DA nerve terminals in the CNS. Therefore, this work suggests that the Mn catalyzed increase in DA auto-oxidation could be linked mechanistically to the appearance of Mn-induced neurotoxic effects.

An electrophysiological study of 2-hexanone and 2,5-hexanedione neurotoxicity in rats.

n-Hexane and its metabolites are neurotoxic to animals and man. Studies have revealed a progressive neuropathy which affects the distal regions of motor and sensory peripheral nerves. This paper describes efforts to determine whether 2-hexanone or 2,5-hexanedione is more neurotoxic than 2-hexanone and that it first affects the distal axon. Concentrations of 20 mM produced no effects after 3 weeks but 40 mM increased distal latency after 2 weeks.

Superoxide generation by 1-nitropyrene in rat lung microsomes.

1-Nitropyrene (1-NP) is a potent mutagen which has been found in diesel exhaust particulates and photocopy toners. 1-NP is known to undergo reduction and oxidation by mammalian enzymes. Research into the biological activity of 1-NP has concentrated on its possible mutagenic and carcinogenic properties. Because other nitro compounds, such as nitrofurantion, are reduced to a nitro anion radical which can react with molecular oxygen to produce superoxide, it was of interest to determine if 1-NP produced superoxide. This study used acetylated cytochrome c/superoxide dismutase as a detection system in a lung microsomal system. Results show that 1-NP catalyzes the formation of superoxide, that the reaction obeys Michaelis-Menten kinetics and that this reaction is saturable. The significance of this study is that 1-NP may have toxic effects which are related to oxidant stress.

Activity of nitro-polynuclear aromatic hydrocarbons in the sister chromatid exchange assay with and without metabolic activation.

Nitro-polynuclear aromatic hydrocarbons are found in diesel particulates. These compounds are potent mutagens in the Ames test. To determine whether nitro-polynuclear aromatic hydrocarbons are active in a mammalian cell assay, 1-nitropyrene, 1,8-dinitropyrene, 2-nitrofluorene, and 4-nitrobiphenyl were incubated with cultures of Chinese hamster ovary cells. The frequency of sister chromatid exchange (SCE) was measured in the presence and absence of rat liver S-9 mix. The addition of S-9 mix resulted in a large increase in the SCEs induced by all four compounds.

Effects of PEG-coupled interleukin-2 on rat lung lavage parameters.

The recombinant lymphokine interleukin-2 (IL-2) has activity in renal cell carcinoma, melanoma, and other cancers. A side effect of IL-2 use is a "capillary leak phenomenon" which is purported to be related to endothelial effects of IL-2 itself or to cells activated by IL-2. We studied IL-2 effects on rat lung lavage parameters to determine whether endothelial damage occurred. The specific endpoints were 125I-albumin extravasation, lavage protein, and lavage angiotensin-converting enzyme (ACE) activity. To ensure sensitivity of these endpoints, we used the known endothelial toxicant thiourea, which increases lung lavage protein and lavage ACE. We found that both PEG IL-2 and thiourea increased the amount of protein and 125-I flux into the lavage. However, although thiourea increased lavage ACE, PEG IL-2 did not. These results suggest that PEG IL-2 can increase protein and iodine flux across the endothelium without causing cell injury.

Behavioral effects of chronic manganese administration in rats: locomotor activity studies.

Manganese (Mn) is an industrially important metal which, when given in excess, produces lesions in the basal ganglia of rats and humans. Humans poisoned with Mn often exhibit an initial hyperactivity ("manganese madness") followed by a parkinsonian-like syndrome. The present studies examined the effects of chronic Mn exposure on locomotor activity in rats maintained on 0.0 or 1.0 mg Mn(Cl)2 X 4H2O/ml drinking water. No differences in mean body weights were observed from 0-65 weeks of treatment. Locomotor activity was tested in 15 min sessions at weekly intervals (Weeks 1-13), then at 4 or 14 week intervals thereafter. Mn treatment produced a significant increase in activity on weeks 5-7 before returning to control values at 8 weeks. Habituation measured within a test session was not affected at any time. At 14 and, to a lesser extent, 29 weeks, Mn animals were found to be more responsive to the effects of 1.25 mg/kg d-amphetamine (d-A) than controls. This increased responsiveness was gone at Weeks 41 and 65. Consistent with clinical reports, these results suggest that Mn may produce a transient increase in dopaminergic function, as measured by both spontaneous and d-A-stimulated locomotor activity.

DNA binding, cardiac superoxide production and cytotoxicity of daunomycin analogs.

Pyridoanthraquinones are potent antibacterial agents especially against gram-positive organisms. We tested two major biologic actions of these compounds: DNA intercalation and superoxide (O2-) production in sarcosomes. Using the bathochromic and hypochromic shifts induced by intercalation, followed by Scatchard analysis, we calculated dissociation constants and the number of binding sites per base pair for several analogues. We compared O2- production using cytochrome c reduction. Unsubstituted compounds do not bind to DNA or change its melting temperature (Tm). Placing a morpholino or piperidyl group at C-5 enhances the binding to DNA. The tetracyclic compounds were equipotent at producing O2- and were 20-fold more active than daunomycin. These compounds were unusual in their solid tumor cytotoxicity.

Identification of 2-nitrofluorene in diesel exhaust particulates.

Diesel exhaust particulates contain mutagens which are direct-acting in the Ames test. A dichloromethane extract of these particulates was separated by liquid chromatography and analyzed by high resolution gas chromatography/high resolution mass spectrometry (HRGC/HRMS). 2-Nitrofluorene, a known carcinogen and direct mutagen, was positively identified by comaxima of ion fragments and retention time on the gas chromatograph.

Surface-tension measurements of pulmonary lavage from ozone-exposed rats.

Ozone, an important component of photochemical air pollution, has been shown to cause morphological and functional changes in the lung after acute, high-level exposure in controlled animal studies. Previous exposures of rats to 0.8 ppm ozone for 18 h showed trends toward decreased lung volumes, as well as modifications in phospholipid composition of lung lavage fluid. These results suggested that exposure to ozone may have diminished the ability of surfactant to reduce surface tension. The purpose of this pilot study was to determine if changes in the surface tension of lavaged pulmonary surfactant occur with ozone exposure. The lavage fluid from rats exposed to ozone at 0.8 ppm for 18 h had a 360% increase in protein and a 30% increase in lipid phosphorus content. Lung lavage samples from ozone-exposed rats were more potent in reducing surface tension as measured on a Wilhelmy plate balance. This difference was evident whether determined with half the total lavage or with equivalent microgram amounts of lipid phosphorus. It is concluded that at this dose and duration of ozone exposure, contrary to our hypothesis, surface-tension-lowering ability of surfactant increases and therefore does not appear to be a contributory factor in the previously observed changes in pulmonary function.