Toxicological analysis of aerosols derived from three electronic nicotine delivery systems using normal human bronchial epithelial cells.

Electronic nicotine delivery systems (ENDS) are a rapidly growing global market advertised as a safer alternative to combustible cigarettes. However, comprehensive investigations of END aerosol physicochemical and toxicological properties have not been fully explored across brands to assess relative safety. In this study, we evaluated aerosols collected from three ENDS - Juul Fruit Medley (5% nicotine), Logic Power (2.4% nicotine), and Mistic (1.8% nicotine). ENDS aerosols were generated using standard machine puffing regimen and collected with a novel fluoropolymer condensation trap. Triple quadrupole-inductively coupled plasma-mass determined the presence of heavy metals in collected aerosols. The toxicological effects of ENDS aerosols on normal human bronchial epithelial cells (NHBE) were investigated using cellular viability, reactive oxygen species, oxidative stress assays, along with DNA damage assessments using the CometChip©. Results indicated the total metal concentrations within collected ENDS aerosols were higher for Mistic and Logic compared to Juul. Logic Power aerosols elicited higher reactive oxygen species levels than Mistic and Juul in NHBE after 24-h exposure. Similar dose-dependent reductions of cellular viability and total glutathione were found for each exposure. However, Logic and Juul aerosols caused greater single stranded DNA damage compared to Mistic. Our study indicates that regardless of brand, ENDS aerosols are toxic to upper airway epithelial cells and may pose a potential respiratory hazard to occasional and frequent users.

Analysis of toxic metals in commercial moist snuff and Alaskan iqmik.

The extent to which smokeless tobacco endangers human health is an ongoing subject of debate. Studies have shown that smokeless tobacco products contain high levels of biologically available nicotine and tobacco-specific nitrosamines. Toxic metals in smokeless tobacco products have been less extensively studied. In this study, concentrations of arsenic, barium, beryllium, cadmium, chromium, cobalt, lead, and nickel were measured in snuff products and iqmik tobacco, a product popular among some Alaska Natives. The average arsenic, cadmium, lead, and nickel concentrations in 17 commercially available brands were 0.23 +/- 0.06 microg/g, 1.40 +/- 0.31 microg/g, 0.45 +/- 0.13 microg/g and 2.28 +/- 0.36 microg/g, respectively. In 17 iqmik tobacco samples, the average arsenic, cadmium, lead, and nickel concentrations were 0.19 +/- 0.06 microg/g, 1.41 +/- 0.56 microg/g, 0.55 +/- 0.19 microg/g, and 2.32 +/- 1.63 microg/g, respectively. Using artificial saliva, the extractable levels of beryllium and lead were relatively low and consistent, whereas barium extracted from tobacco samples ranged from 2 to 21%. The group 1 and 2B carcinogens cadmium, cobalt, and nickel were more efficiently extracted by artificial saliva (30-65% of the cobalt, 20-46% of the nickel, and 21-47% of the cadmium).

Cadmium, lead, and thallium in smoke particulate from counterfeit cigarettes compared to authentic US brands.

Smoking remains the leading cause of preventable disease in the United States. Exposure to tobacco smoke leads to cancer, heart and lung disease, and addiction. The origin of the tobacco and cigarette manufacturing practices of counterfeit cigarettes are unknown. Because toxic metals are incorporated into the tobacco lamina during cultivation, the ambient metal content of the soil could produce significant differences in metal levels in both the tobacco and smoke of counterfeit cigarettes. We compared mainstream smoke cadmium, thallium, and lead deliveries from counterfeit and authentic brands. Mainstream smoke levels of all three metals were far greater for counterfeit than the authentic brands, in some cases by an order of magnitude. Significant differences still existed even after normalizing mainstream smoke metal levels with nicotine delivery; the counterfeits typically delivered much higher levels of all three analytes. Our findings, based on 21 different counterfeit samples, suggest that counterfeit cigarettes potentially result in a markedly greater exposure to toxic heavy metals than authentic brands, even after correcting for differences in nicotine intake. In view of the unknown health risks associated with inhaling higher levels of toxic metals, it is prudent to minimize exposure to toxic substances whenever possible.

Cadmium, lead, and thallium in mainstream tobacco smoke particulate.

The deliveries of cadmium, thallium, and lead in mainstream smoke particulate from cigarettes with different smoke delivery designs were determined by inductively coupled plasma-mass spectrometry in order to investigate their impact on the delivery of these known toxic compounds. Analyses showed that the levels of all three metals in smoke particulate were associated with their tar delivery category. After normalizing the metal concentrations to tar, there were no longer any statistically significant delivery differences between full-flavor, light or ultra-light cigarettes. When the concentrations were normalized to nicotine, the mean levels from the three delivery groups were much smaller than before normalization. But unlike the case using tar to normalize, in some of the cases, there were still some statistically significant differences in the nicotine-normalized results. These findings suggest that if smokers compensate for differences in nicotine intake, they receive exposures to toxic heavy metals from ultra-light, light and full-flavor cigarettes that are more similar than results would suggest from using the Federal Trade Commission method alone.

X-ray crystallographic identification of a protein-binding site for both all-trans- and 9-cis-retinoic acid.

The elucidation of how a protein-binding site might specifically recognize both the all-trans and 9-cis isomers of retinoic acid is of particular interest because of the recently discovered binding specificities of the nuclear receptors for retinoic acid. Two families of nuclear receptors for retinoic acid have been described, which are designated RAR (for retinoic acid receptor) and RXR (for retinoid-X receptor). The RXR family of receptors is specific for 9-cis-retinoic acid, whereas the RAR-type receptor is activated by either 9-cis- or all-trans-retinoic acid. During the x-ray structure determination of a secreted epididymal retinoic acid-binding protein, with and without retinoic acid, we observed an electron density for the bound all-trans-retinoic acid that indicates the protein-bound all-trans form of the vitamin/hormone adopts a horseshoe-like conformation that resembles the structure of the 9-cis isomer of the ligand. We detail here the experiments that indicate the electron density is indeed due to all-trans-retinoic acid and that protein can also bind the 9-cis isomer. This observation and the fact that the same protein also binds the synthetic retinoid (E)-4-[2-(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthalenyl)-1- propenyl]-benzoic acid (TTNPB), a retinoic acid analog that activates RAR but does not activate RXR, suggest that the mechanism by which this protein recognizes both 9-cis- and all-trans-retinoic acids may be analogous to the mechanism used by RAR. Three crystallographic structures of retinol-binding proteins have been described. In each of these structures the retinol binds with the isoprene tail fully extended. This report represents an x-ray crystallographic description of a protein-bound retinoid conformer that adopts a nonextended conformation, and we believe this observation is relevant to the ligand specificities described for the retinoic acid receptors.

Endogenous retinoids in rat epididymal tissue and rat and human spermatozoa.

Recent work has demonstrated high levels of retinoid binding proteins in rat epididymis, and a lumenal retinoic acid binding protein has been purified. These findings suggested that vitamin A may be involved in spermatozoal maturation in the epididymis. We further addressed this question by quantifying retinol, retinyl esters, and retinoic acid isomers from perfused epididymal tissue, from rat testicular and epididymal spermatozoa, and from human ejaculate sperm. HPLC showed vitamin A levels to be higher in caput than in corpus or cauda tissue. Retinoic acid and 9-cis-retinoic acid were found to be graded from lowest levels in caput to highest in cauda. Spermatozoa from caput epididymidis and enriched testicular spermatozoa were found to have higher levels of vitamin A than did spermatozoa from corpus or cauda epididymidis. Spermatozoal retinyl esters had acyl substituents similar to those seen in whole epididymis, and diminished in quantity in sperm from distal segments. Human ejaculate sperm were found to retain high levels of retinyl palmitate and stearate. Retinol and retinoic acid were only marginally detectable in human sperm. Retention of retinoids in mature spermatozoa suggests roles for vitamin A in spermatozoal reproductive physiology beyond the epididymal stage.

Monomer sequence determination of carbohydrates using fast-atom bombardment mass spectrometry of periodate-oxidized acetate ester derivatives.

A derivatization method, adapted from that of Angel et al. (ref. 10), for sequencing sugar residues in partially degraded poly- and oligo-saccharides using positive-ion f.a.b.-m.s. is described. Derivative selection provides sequence information by directing fragmentation exclusively to both sides of glycosidic oxygen atoms and, in the case of opened rings, between glycosidic carbon and ring oxygen atoms. Polysaccharides or oligosaccharides are subjected to sequential periodate oxidation, borodeuteride reduction, and acetylation. The derivatized polysaccharides are then subjected to partial degradation, acetylation, and high-performance liquid chromatography (h.p.l.c.) purification. F.a.b.-m.s. data obtained on model compounds, using 3-nitrobenzyl alcohol as matrix for f.a.b.-m.s., demonstrated direction of fragmentation to both sides of the glycosidic oxygen atom in unoxidized residues, and to both sides of the acetal oxygen atoms in oxidized residues. Oligosaccharide linkage and sequence may thus be determined by observing fragmentation from both the reducing and non-reducing ends of the molecule. Two Salmonella lipopolysaccharides, derivatized by this procedure, were partially hydrolyzed and then acetylated. Analysis of the h.p.l.c.-purified oligosaccharide derivatives by f.a.b.-m.s. demonstrated the applicability of the technique for sequencing nmol quantities of branched structures.