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Hong J, Porter DW, Sreenivasan R, McIntyre PC, Bent SF. ALD resist formed by vapor-deposited self-assembled monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2007; 23:1160-5. [PMID: 17241027 DOI: 10.1021/la0606401] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
A new process of applying molecular resists to block HfO2 and Pt atomic layer deposition has been investigated. Monolayer films are formed from octadecyltrichlorosilane (ODTS) or tridecafluoro-1,1,2,2-tetrahydrooctyltrichlorosilane (FOTS) and water vapor on native silicon oxide surfaces and from 1-octadecene on hydrogen-passivated silicon surfaces through a low-pressure chemical vapor deposition process. X-ray photoelectron spectroscopy data indicates that surfaces blocked by these monolayer resists can prevent atomic layer deposition of both HfO2 and Pt successfully. Time-dependent studies show that the ODTS monolayers continue to improve in blocking ability for as long as 48 h of formation time, and infrared spectroscopy measurements confirm an evolution of packing order over these time scales.
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Fields AT, Porter DW, Callery PS, Harvey EB, Loberg MD. Synthesis and radiolabeling of technetium radiopharmaceuticals based on N-substituted iminodiacetic acid: Effect of radio-labeling conditions on radiochemical purity. J Labelled Comp Radiopharm 2006. [DOI: 10.1002/jlcr.2580150145] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Huffman LJ, Beighley CM, Frazer DG, McKinney WG, Porter DW. Increased susceptibility of the lungs of hyperthyroid rats to oxidant injury: specificity of effects. Toxicology 2006; 225:119-27. [PMID: 16797819 DOI: 10.1016/j.tox.2006.05.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2005] [Revised: 04/28/2006] [Accepted: 05/13/2006] [Indexed: 01/28/2023]
Abstract
Results from previous studies indicate that hyperthyroidism increases the risk of ozone-induced lung toxicity. This observation raised the possibility that pulmonary damage from other oxidant substances might be greater in a hyperthyroid state. To address this hypothesis, pulmonary responses to crystalline silica, a particulate with oxidant properties, were evaluated in normal or hyperthyroid adult male rats. To induce a hyperthyroid condition, time-release pellets containing thyroxine were implanted subcutaneously; control rats received placebo pellets. After 7 days, the animals were exposed to saline or silica (0.1mg/100g BW or 1.0mg/100g BW) by intratracheal instillation. Following silica treatment, there was a dose-related increase in bronchoalveolar lavage (BAL) albumin levels and neutrophil numbers. However, the effects of silica were similar in both normal and hyperthyroid rats. These findings were confirmed and contrasted with those regarding ozone (1ppm, 4h inhalation) in a subsequent experiment. The results indicated that, although exposure to either ozone or silica resulted in increases in BAL albumin levels and neutrophil numbers, only responses to ozone were enhanced in hyperthyroid rats. These findings suggest that specificity exists in regards to the modulation of oxidant-induced lung damage and inflammation by thyroid hormones.
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Filler MA, Keung AJ, Porter DW, Bent SF. Formation of Surface-Bound Acyl Groups by Reaction of Acyl Halides on Ge(100)−2×1. J Phys Chem B 2006; 110:4115-24. [PMID: 16509705 DOI: 10.1021/jp055685+] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have investigated the reaction of a series of acyl halides, including acetyl chloride, acetyl bromide, acetyl-d3 chloride, benzoyl chloride, and pivaloyl chloride, on Ge(100)-2x1 with multiple internal reflection infrared (MIR-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT). Infrared spectra following saturation exposures of acetyl chloride and acetyl bromide to Ge(100)-2x1 at 310 K are nearly identical, both exhibiting strong nu(C=O) stretching peaks near 1685 cm-1 and no vibrational modes in the nu(Ge-H) region. These data provide strong evidence for the presence of a surface-bound acetyl group on Ge(100)-2x1, which results from a C-X dissociation reaction (where X=Cl, Br). For acetyl chloride, DFT calculations predict that the barrier to C-Cl dissociation is only 1 kcal/mol above a chlorine-bound precursor state and is considerably smaller than barriers leading to the [2+2] C=O cycloaddition and alpha-CH dissociation products. In addition to the C-X dissociation product, both infrared and photoelectron results point to the presence of a second structure for acetyl halides where the oxygen of the surface-bound acetyl group donates charge to a nearby surface atom. This interaction is not observed for benzoyl chloride and pivaloyl chloride.
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Huffman LJ, Beighley CM, Frazer DG, McKinney WG, Porter DW. Increased susceptibility of hyperthyroid rats to ozone: early events and mechanisms. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2006; 69:465-79. [PMID: 16574622 DOI: 10.1080/15287390500247017] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Previous studies demonstrated that ozone-induced lung damage and inflammation are much greater in hyperthyroid rats, compared to normal rats, at 18 h postexposure. The purpose of the present investigation was to study early events and mechanisms underlying the increased sensitivity to ozone in a hyperthyroid state. Specifically, the degree of lung epithelial cell barrier disruption, the antioxidant status of the extracellular lining fluid, and the release of inflammatory mediators were examined. To induce a hyperthyroid state, mature male Sprague-Dawley rats were implanted with time-release pellets containing thyroxine; control rats received placebo pellets. After 7 d, the animals were exposed to air or ozone (2 ppm, 3 h). Immediately following the end of the exposure, bronchoalveolar lavage (BAL) fluid and cells were harvested. BAL fluid albumin levels and total antioxidant status were examined. In addition, levels of prostaglandin E2 (PGE2), macrophage inflammatory protein (MIP)-2, MCP-1, and tumor necrosis factor (TNF)-alpha were determined in BAL fluid and in media samples following ex vivo culture of BAL cells harvested after in vivo inhalation exposures. The results of this study are consistent with the following hypotheses: (1) A marked increase in the permeability of the alveolar-capillary barrier is an early event following ozone exposure in a hyperthyroid state; however this does not appear to be due to overall changes in BAL fluid antioxidant potential. (2) Early increases in MIP-2, but not PGE2, are involved in the enhanced lung response to ozone in a hyperthyroid state. (3) Inflammatory mediator production (i.e., PGE2, MIP-2, MCP-1, and TNF-alpha) by alveolar macrophages plays a minimal role in the initial responses to ozone in a hyperthyroid state.
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Courtney SM, Hay PA, Buck RT, Colville CS, Porter DW, Scopes DIC, Pollard FC, Page MJ, Bennett JM, Hircock ML, McKenzie EA, Stubberfield CR, Turner PR. 2,3-Dihydro-1,3-dioxo-1H-isoindole-5-carboxylic acid derivatives: a novel class of small molecule heparanase inhibitors. Bioorg Med Chem Lett 2005; 14:3269-73. [PMID: 15149688 DOI: 10.1016/j.bmcl.2004.03.086] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2004] [Revised: 03/26/2004] [Accepted: 03/29/2004] [Indexed: 11/29/2022]
Abstract
A novel class of 2,3-dihydro-1,3-dioxo-1H-isoindole-5-carboxylic acids are described as inhibitors of the endo-beta-glucuronidase heparanase. Several of the compounds, for example, 2-[4-propylamino-5-[5-(4-chloro)phenyl-benzoxazol-2-yl]phenyl]-2,3-dihydro-1,3-dioxo-1H-isoindole-5-carboxylic acid (9c), display potent heparanase inhibitory activity (IC(50) 200-500 nM) and have high selectivity (>100-fold) over human beta-glucuronidase. They also show anti-angiogenic effects. Such compounds should serve as useful biological tools and may provide a basis for the design of novel therapeutic agents.
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Porter DW, Gupte GL, Brown RM, Spray C, English MW, deVille DeGoyet J, McKiernan PJ. Histiocytic sarcoma with interdigitating dendritic cell differentiation. J Pediatr Hematol Oncol 2004; 26:827-30. [PMID: 15591905] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 03/05/2023]
Abstract
The authors describe a rare tumor with overlapping features of true histiocytic sarcoma and interdigitating dendritic cell sarcoma occurring in infancy. A 3-month-old boy presented with hepatosplenomegaly and abdominal distention. He presented a diagnostic challenge at initial presentation despite extensive investigations. On follow-up at age 16 months he had progressive splenomegaly, thrombocytopenia, and worsening coagulopathy. A diagnosis of histiocytic sarcoma with interdigitating dendritic cell differentiation was established after an open biopsy of liver and spleen. A repeat liver biopsy coupled with splenic biopsy is recommended in young children with unexplained hepatosplenomegaly and thrombocytopenia.
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Orchard MG, Neuss JC, Galley CMS, Carr A, Porter DW, Smith P, Scopes DIC, Haydon D, Vousden K, Stubberfield CR, Young K, Page M. Rhodanine-3-acetic acid derivatives as inhibitors of fungal protein mannosyl transferase 1 (PMT1). Bioorg Med Chem Lett 2004; 14:3975-8. [PMID: 15225710 DOI: 10.1016/j.bmcl.2004.05.050] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2004] [Revised: 05/17/2004] [Accepted: 05/21/2004] [Indexed: 11/24/2022]
Abstract
The first inhibitors of fungal protein: mannosyl transferase 1 (PMT1) are described. They are based upon rhodanine-3-acetic acid and several compounds have been identified, for example, 5-[[3-(1-phenylethoxy)-4-(2-phenylethoxy)phenyl]methylene]-4-oxo-2-thioxo-3-thiazolidineacetic acid (5a), which inhibit Candida albicans PMT1 with IC(50)s in the range 0.2-0.5 microM. Members of the series are effective in inducing changes in morphology of C. albicans in vitro that have previously been associated with loss of the transferase activity. These compounds could serve as useful tools for studying the effects of protein O-mannosylation and its relevance in the search for novel antifungal agents.
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Hermet JPR, McGrath MJ, O'Brien P, Porter DW, Gilday J. Concise asymmetric synthesis of (−)-sparteine. Chem Commun (Camb) 2004:1830-1. [PMID: 15306905 DOI: 10.1039/b406632d] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A six-step asymmetric synthesis of natural (-)-sparteine from ethyl 7-iodohept-2-enoate is reported, involving a connective Michael addition of an amino ester-derived enolate to an alpha,beta-unsaturated amino ester.
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Huffman LJ, Prugh DJ, Millecchia L, Schuller KC, Cantrell S, Porter DW. Nitric oxide production by rat bronchoalveolar macrophages or polymorphonuclear leukocytes following intratracheal instillation of lipopolysaccharide or silica. J Biosci 2003; 28:29-37. [PMID: 12682422 DOI: 10.1007/bf02970129] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
Exposure of the lung to lipopolysaccharide (LPS) or silica results in an activation of alveolar macrophages (AMs), recruitment of polymorphonuclear leukocytes (PMNs) into bronchoalveolar spaces, and the production of free radicals. Nitric oxide (NO) is one of the free radicals generated by bronchoalveolar lavage (BAL) cell populations following either LPS or silica exposure. The purpose of the present study was to assess the relative contributions of AMs and PMNs to the amounts of NO produced by BAL cells following intratracheal (IT) instillation of either LPS or silica. Male Sprague Dawley rats (265-340 g body wt.) were given LPS (10 mg/100 g body wt.) or silica (5 mg/100 g body wt.). BAL cells were harvested 18-24 h post-IT and enriched for AMs or PMNs using density gradient centrifugation. Media levels of nitrate and nitrite (NOx; the stable decomposition products of NO) were then measured 18 h after ex vivo culture of these cells. Following IT exposure to either LPS or silica, BAL cell populations were approximately 20% AMs and approximately 80% PMNs. After density gradient centrifugation of BAL cells from LPS- or silica-treated rats, cell fractions were obtained which were relatively enriched for AMs (approximately 60%) or PMNs (approximately 90%). The amounts of NOx produced by the AM-enriched fractions from LPS- or silica-treated rats were approximately 2-4-fold greater than that produced by the PMN-enriched fractions. Estimations of the relative contribution of AMs or PMNs to the NOx produced indicated that: (i) following LPS treatment, 75%-89% of the NOx was derived from AMs and 11%-25% from PMNs; and (ii) following silica treatment, 76%-100% of the NOx was derived from AMs and 0-24% from PMNs. Immunohistochemistry for inducible NO synthase on lung tissue sections supported these findings. We conclude that AMs are the major source of the NO produced by BAL cells during acute pulmonary inflammatory responses to LPS or silica.
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Hermet JPR, Porter DW, Dearden MJ, Harrison JR, Koplin T, O'Brien P, Parmene J, Tyurin V, Whitwood AC, Gilday J, Smith NM. Synthesis of sparteine-like chiral diamines and evaluation in the enantioselective lithiation–substitution of N-(tert-butoxycarbonyl)pyrrolidine. Org Biomol Chem 2003; 1:3977-88. [PMID: 14664387 DOI: 10.1039/b308410h] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Three chiral diamines were synthesised and evaluated as sparteine surrogates in the lithiation-substitution of N-(tert-butoxycarbonyl)pyrrolidine. The synthesis and attempted resolution of sparteine-like diamines [(1S*,2R*,8R*)-10-methyl-6,10-diazatricyclo[6.3.1.0(2,6)]dodecane and (1S*,2R*,9R*)-11-methyl-7,11-diazatricyclo[7.3.1.0(2,7)]tridecane] (via inclusion complex formation) are reported. Unfortunately, it was only possible to resolve the diazatricyclo[7.3.1.0(2,7)]tridecane compound. An alternative route to (1R,2S,9S)-11-methyl-7,11-diazatricyclo[7.3.1.0(2,7)]tridecane starting from the natural product, (-)-cytisine, is described. This simple three-step route furnished gram-quantities of a (+)-sparteine surrogate. X-Ray crystallography of an intermediate in the route, (1R,5S,12S)-3-methoxycarbonyldecahydro-1,5-methanopyrido[1,2-a][1,5]diazocin-8-one, enabled the stereochemistry of all of the tricyclic diamines described in this paper to be unequivocally established. Two other diamines, starting from (S)-proline and resolved 2-piperidine ethanol, were prepared using standard methods. These diamines lacked the bispidine framework of (-)-sparteine and were found to impart vastly inferior enantioselectivity. It was concluded that, for the asymmetric lithiation substitution of N-Boc pyrrolidine, a rigid bispidine framework and only three of the four rings of (-)-sparteine are needed for high enantioselectivity. Furthermore, it is shown that diamine (1R,2S,9S)-11-methyl-7,11-diazatricyclo[7.3.1.0(2,7)]tridecane is the first successful (+)-sparteine surrogate.
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Hubbs AF, Battelli LA, Goldsmith WT, Porter DW, Frazer D, Friend S, Schwegler-Berry D, Mercer RR, Reynolds JS, Grote A, Castranova V, Kullman G, Fedan JS, Dowdy J, Jones WG. Necrosis of nasal and airway epithelium in rats inhaling vapors of artificial butter flavoring. Toxicol Appl Pharmacol 2002; 185:128-35. [PMID: 12490137 DOI: 10.1006/taap.2002.9525] [Citation(s) in RCA: 91] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
As the result of a high prevalence of fixed airways obstruction in workers at a microwave popcorn manufacturing plant, we examined the hypothesis that vapors of butter flavoring used in the manufacture of microwave popcorn and other foods can produce airway injury in rats. Rats were exposed to vapors liberated from heated butter flavoring. Rats were exposed for 6 h by inhalation and were necropsied 1 day after exposure. The exposure was found by GC-MS analysis to be a complex mixture of various organic gases with the major peaks consisting of diacetyl (2,3-butanedione), acetic acid, acetoin (3-hydroxy-2-butanone), butyric acid, acetoin dimers, 2-nonanone, and delta-alkyl lactones. Diacetyl was used as a marker of exposure concentration. In the lung, butter flavoring vapors containing 285-371 ppm diacetyl caused multifocal, necrotizing bronchitis, which was most consistently present in the mainstem bronchus. Alveoli were unaffected. Butter flavoring vapors containing 203-371 ppm diacetyl caused necrosuppurative rhinitis, which affected all four levels of the nose. Within the posterior two nasal levels (T3 and T4), necrosis and inflammation was principally localized to the nasopharyngeal duct. Control rats were unaffected. Therefore, concentrations of butter flavoring vapors that can occur during the manufacture of foods are associated with epithelial injury in the nasal passages and pulmonary airways of rats.
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Young SH, Robinson VA, Barger M, Porter DW, Frazer DG, Castranova V. Acute inflammation and recovery in rats after intratracheal instillation of a 1-->3-beta-glucan (zymosan A). JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2001; 64:311-325. [PMID: 11693490 DOI: 10.1080/152873901316981303] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Although endotoxin is a known potent stimulant of inflammatory responses, the magnitude of pulmonary response following exposure to various organic dusts does not always correlate with endotoxin content of the dusts alone. Other components, such as 1-->3-beta-glucans, derived from the inner cell wall of yeasts and fungi, have been implicated in organic dust toxic syndrome. However, animal studies report conflicting results concerning the inflammatory potency of 1-->3-beta-glucan. In this experiment, the pulmonary reaction of rats to 1-->3-beta-glucan (zymosan A) exposure was assessed. Male Sprague-Dawley rats were exposed via intratracheal instillation (IT) to zymosan A (dose range 0-5 mg/kg body weight). Rats were sacrificed 1-7 d postexposure and the following pulmonary responses were monitored: (1) breathing frequency, (2) differential cell counts of hronchoalveolar lavage (BAL) cells, (3) chemiluminescence (CL) as a measure of alveolar macrophage activation, (4) nitric oxide production by alveolar macrophages, (5) albumin levels, and (6) lactate dehydrogenase (LDH) activity in the first acellular lavage fluid. Upon challenge with zymosan A, rats exhibited a dose-dependent pulmonary response at 1 d post IT that was significantly higher than the control level at a dose of 1-2.5 mg/kg body weight for each of these pulmonary parameters. Post-IT enhancement of breathing frequencies and polymorphonuclear leukocytes (PMN) obtained by BAL both correlated very well with zymosan A concentration (r = .95 and .99, respectively). Elevation of albumin levels and LDH activity of the acellular BAL fluid also correlated (r = .80) with the dose of zymosan. The recovery from a single intratracheal administration of zymosan A (2.5 mg/kg body weight) was monitored over 7 d. PMN and CL showed significant recovery from d 1 level by 3 d postexposure. Breathing frequencies and nitric oxide production showed significant recovery from d 1 level by 4 d postexposure. A good correlation (r2= .8) between recovery of PMN in BAL, CL, or nitric oxide production and the days postexposure was observed.
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Kuempel ED, Tran CL, Bailer AJ, Porter DW, Hubbs AF, Castranova V. Biological and statistical approaches to predicting human lung cancer risk from silica. J Environ Pathol Toxicol Oncol 2001; 20 Suppl 1:15-32. [PMID: 11570671] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023] Open
Abstract
Chronic inflammation is a key step in the pathogenesis of particle-elicited fibrosis and lung cancer in rats, and possibly in humans. In this study, we compute the excess risk estimates for lung cancer in humans with occupational exposure to crystalline silica, using both rat and human data, and using both a threshold approach and linear models. From a toxicokinetic/dynamic model fit to lung burden and pulmonary response data from a subchronic inhalation study in rats, we estimated the minimum critical quartz lung burden (Mcrit) associated with reduced pulmonary clearance and increased neutrophilic inflammation. A chronic study in rats was also used to predict the human excess risk of lung cancer at various quartz burdens, including mean Mcrit (0.39 mg/g lung). We used a human kinetic lung model to link the equivalent lung burdens to external exposures in humans. We then computed the excess risk of lung cancer at these external exposures, using data of workers exposed to respirable crystalline silica and using Poisson regression and lifetable analyses. Finally, we compared the lung cancer excess risks estimated from male rat and human data. We found that the rat-based linear model estimates were approximately three times higher than those based on human data (e.g., 2.8% in rats vs. 0.9-1% in humans, at mean Mcrit lung burden or associated mean working lifetime exposure of 0.036 mg/m3). Accounting for variability and uncertainty resulted in 100-1000 times lower estimates of human critical lung burden and airborne exposure. This study illustrates that assumptions about the relevant biological mechanism, animal model, and statistical approach can all influence the magnitude of lung cancer risk estimates in humans exposed to crystalline silica.
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Porter DW, Ramsey D, Hubbs AF, Battelli L, Ma J, Barger M, Landsittel D, Robinson VA, McLaurin J, Khan A, Jones W, Teass A, Castranova V. Time course of pulmonary response of rats to inhalation of crystalline silica: histological results and biochemical indices of damage, lipidosis, and fibrosis. J Environ Pathol Toxicol Oncol 2001; 20 Suppl 1:1-14. [PMID: 11570667] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023] Open
Abstract
Previous studies have determined that alpha-quartz (crystalline silica) can cause pulmonary inflammation, damage, and fibrosis. However, the temporal relationship between silica inhalation and pulmonary inflammation, damage, and fibrosis has not been fully examined. To address this gap in our knowledge of silica-induced pulmonary fibrosis, a chronic inhalation study using rats was designed. Specifically, rats were exposed to a silica aerosol (15 mg/m3 silica, 6 h/d, 5 d/wk, 116 d), and measurements of pulmonary inflammation, damage, and fibrosis were monitored throughout the study. We report (1) data demonstrating that the silica aerosol generation and exposure system produced a consistent silica aerosol of respirable size particles; (2) the time course of silica deposition in the lung; (3) calculations that demonstrate that the rats were not in pulmonary overload; (4) histopathological data demonstrating time-dependent enhancement of silica-induced alveolitis, epithelial hypertrophy and hyperplasia, alveolar lipoproteinosis, and pulmonary fibrosis in the absence of overload; and (5) biochemical data documenting the development of lipidosis, lung damage, and fibrosis.
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Hubbs AF, Minhas NS, Jones W, Greskevitch M, Battelli LA, Porter DW, Goldsmith WT, Frazer D, Landsittel DP, Ma JY, Barger M, Hill K, Schwegler-Berry D, Robinson VA, Castranova V. Comparative pulmonary toxicity of 6 abrasive blasting agents. Toxicol Sci 2001; 61:135-43. [PMID: 11294984 DOI: 10.1093/toxsci/61.1.135] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Inhalation of silica dust is associated with pulmonary fibrosis. Therefore, substitute abrasive materials have been suggested for use in abrasive blasting operations. To date, toxicological evaluation of most substitute abrasives has been incomplete. Therefore, the objective of this study was to compare the pulmonary toxicity of a set of substitute abrasives (garnet, staurolite, coal slag, specular hematite, and treated sand) to that of blasting sand. Rats were exposed to blasting sand or an abrasive substitute by intratracheal instillation and pulmonary responses to exposure were monitored 4 weeks postexposure. Pulmonary damage was monitored as lactate dehydrogenase (LDH) in the acellular lavage fluid. Pulmonary inflammation was evaluated from the yield of polymorphonuclear leukocytes (PMN) obtained by bronchoalveolar lavage. The activity of alveolar macrophages was determined by measuring zymosan-stimulated chemiluminescence. Blasting sand caused lung damage and showed histologic evidence for inflammation and fibrosis. Garnet, staurolite, and treated sand exhibited toxicity and inflammation that were similar to blasting sand, while coal slag caused greater pulmonary damage and inflammation than blasting sand. In contrast, specular hematite did not significantly elevate LDH or PMN levels and did not stimulate macrophage activity 4 weeks postexposure.
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Harrison JR, O′Brien P, Porter DW, Smith NM. Evaluation of a sparteine-like diamine for asymmetric synthesis. Chem Commun (Camb) 2001. [DOI: 10.1039/b103220h] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Burkhart J, Jones W, Porter DW, Washko RM, Eschenbacher WL, Castellan RM. Hazardous occupational exposure and lung disease among nylon flock workers. Am J Ind Med 1999; Suppl 1:145-6. [PMID: 10519816 DOI: 10.1002/(sici)1097-0274(199909)36:1+<145::aid-ajim51>3.0.co;2-f] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Baskin SI, Porter DW, Rockwood GA, Romano JA, Patel HC, Kiser RC, Cook CM, Ternay AL. In vitro and in vivo comparison of sulfur donors as antidotes to acute cyanide intoxication. J Appl Toxicol 1999. [PMID: 10362268 DOI: 10.1002/(sici)1099-1263(199905/06)19:] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Antidotes for cyanide (CN) intoxication include the use of sulfane sulfur donors (SSDs), such as thiosulfate, which increase the conversion of CN to thiocyanate by the enzyme rhodanese. To develop pretreatments that might be useful against CN, SSDs with greater lipophilicity than thiosulfate were synthesized and assessed. The ability of SSDs to protect mice against 2LD50 of sodium cyanide (NaCN) administered either 15 or 60 min following administration of an SSD was assessed. To study the mechanism of action of the SSD, the candidate compounds were examined in vitro for their effect on rhodanese and 3-mercaptopyruvate sulfurtransferase (MST) activity under increasing SSD concentrations. Tests were conducted on nine candidate SSDs: ICD1021 (3-hydroxypyridin-2-yl N-[(N-methyl-3-aminopropyl)]-2-aminoethyl disulfide dihydrochloride), ICD1022, (3-hydroxypyridin-2-yl N-[(N-methyl-3-aminopropyl)]-2-aminoethyl disulfide trihydrochloride), ICD1584 (diethyl tetrasulfide), ICD1585 (diallyl tetrasulfide), ICD1587 (diisopropyl tetrasulfide); ICD1738 (N-(3-aminopropyl)-2-aminoethyl 2-oxopropyl disulfide dihydrochloride), ICD1816 (3,3'-tetrathiobis-N-acctyl-L-alanine), ICD2214 (2-aminoethyl 4-methoxyphenyl disulfide hydrochloride) and ICD2467 (bis(4-methoxyphenyl) disulfide). These tests demonstrated that altering the chemical substituent of the longer chain sulfide modified the ability of the candidate SSD to protect against CN toxicity. At least two of the SSDs at selected doses provided 100% protection against 2LD50 of NaCN, normally an LD99. All compounds were evaluated using locomotor activity as a measure of potential adverse behavioral effects. Positive hypoactivity relationships were found with several disulfides but none was found with ICD1584, a tetrasulfide. Separate studies suggest that the chemical reaction of potassium cyanide (KCN) and cystine forms the toxic metabolite 2-iminothiazolidine-4-carboxylic acid. An alternative detoxification pathway, one not primarily involving the sulfur transferases. may be important in pretreatment for CN intoxication. Although studies to elucidate the precise mechanisms are needed. it is clear that these newly synthesized compounds provide a new rationale for anti-CN drugs, with fewer side-effects than the methemoglobin formers.
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Porter DW, Castranova V, Robinson VA, Hubbs AF, Mercer RR, Scabilloni J, Goldsmith T, Schwegler-Berry D, Battelli L, Washko R, Burkhart J, Piacitelli C, Whitmer M, Jones W. Acute inflammatory reaction in rats after intratracheal instillation of material collected from a nylon flocking plant. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 1999; 57:25-45. [PMID: 10321900 DOI: 10.1080/009841099157845] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/19/2023]
Abstract
Several cases of interstitial lung disease have been diagnosed among workers at a nylon flock plant, but the etiologic agent for the disease outbreak was unknown. The results of a medical survey and industrial hygiene study indicated that the dust present in the plant may be responsible. Thus, airborne dust collected at the plant was examined for its inflammatory potential in rat lungs. The endpoints measured were: (1) breathing rates, (2) differential cell counts of bronchoalveolar lavage cells, (3) alveolar macrophage (AM) chemiluminescence, (4) albumin concentration and matrix metalloprotease activities in the acellular fluid from the initial bronchoalveolar lavage, and (5) pulmonary histopathology. In the first study, rats received a single dose of the airborne dust sample (10 mg/kg body weight) by intratracheal (IT) instillation. At 1 d post-IT, all inflammatory endpoints were significantly increased versus controls, but by 29 d post-IT they did not differ significantly from controls. Histopathology demonstrated mild to moderate, multifocal, suppurative pneumonia, usually centered around bronchioles, at 1 d post-IT. At 29 d post-IT, pulmonary inflammation was minimal to mild and characterized by alveolar histocytosis usually restricted to the immediate area of retained bire-fringent fibers. In subsequent experiments, airborne dust was extracted with water and the dust (washed airborne dust) and water extract (soluble fraction) were separated by centrifugation for further study. Nylon tow dust was prepared in the laboratory by milling uncut nylon strands (called tow) that had not been treated with the finish or dyes that are commonly used in the flock plants. Rats were administered a single dose of a dust sample (10 mg/kg body weight) or the soluble fraction (1.3 ml/kg body weight) by IT administration and the same endpoints were measured at 1 d post-IT. The dust samples caused significant increases in all of the inflammatory endpoints; however, the soluble fraction was much less active. Histological analysis of the lungs 1 d post-IT confirmed lung inflammation was occurring and tended to center around bronchioles. The results suggest that: (1) nylon flocking generates particles of respirable size that can interact with AM in the lung and can be detected in the lung 29 d after exposure, (2) the dust samples examined cause an inflammatory response, (3) water-extractable agent(s) from airborne dust contribute only minimally to the inflammatory response, and (4) the acute inflammatory response to these dusts is substantial when compared to other pathologic occupational dusts previously examined in our laboratory.
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Baskin SI, Porter DW, Rockwood GA, Romano JA, Patel HC, Kiser RC, Cook CM, Ternay AL. In vitro and in vivo comparison of sulfur donors as antidotes to acute cyanide intoxication. J Appl Toxicol 1999; 19:173-83. [PMID: 10362268 DOI: 10.1002/(sici)1099-1263(199905/06)19:3<173::aid-jat556>3.0.co;2-2] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Antidotes for cyanide (CN) intoxication include the use of sulfane sulfur donors (SSDs), such as thiosulfate, which increase the conversion of CN to thiocyanate by the enzyme rhodanese. To develop pretreatments that might be useful against CN, SSDs with greater lipophilicity than thiosulfate were synthesized and assessed. The ability of SSDs to protect mice against 2LD50 of sodium cyanide (NaCN) administered either 15 or 60 min following administration of an SSD was assessed. To study the mechanism of action of the SSD, the candidate compounds were examined in vitro for their effect on rhodanese and 3-mercaptopyruvate sulfurtransferase (MST) activity under increasing SSD concentrations. Tests were conducted on nine candidate SSDs: ICD1021 (3-hydroxypyridin-2-yl N-[(N-methyl-3-aminopropyl)]-2-aminoethyl disulfide dihydrochloride), ICD1022, (3-hydroxypyridin-2-yl N-[(N-methyl-3-aminopropyl)]-2-aminoethyl disulfide trihydrochloride), ICD1584 (diethyl tetrasulfide), ICD1585 (diallyl tetrasulfide), ICD1587 (diisopropyl tetrasulfide); ICD1738 (N-(3-aminopropyl)-2-aminoethyl 2-oxopropyl disulfide dihydrochloride), ICD1816 (3,3'-tetrathiobis-N-acctyl-L-alanine), ICD2214 (2-aminoethyl 4-methoxyphenyl disulfide hydrochloride) and ICD2467 (bis(4-methoxyphenyl) disulfide). These tests demonstrated that altering the chemical substituent of the longer chain sulfide modified the ability of the candidate SSD to protect against CN toxicity. At least two of the SSDs at selected doses provided 100% protection against 2LD50 of NaCN, normally an LD99. All compounds were evaluated using locomotor activity as a measure of potential adverse behavioral effects. Positive hypoactivity relationships were found with several disulfides but none was found with ICD1584, a tetrasulfide. Separate studies suggest that the chemical reaction of potassium cyanide (KCN) and cystine forms the toxic metabolite 2-iminothiazolidine-4-carboxylic acid. An alternative detoxification pathway, one not primarily involving the sulfur transferases. may be important in pretreatment for CN intoxication. Although studies to elucidate the precise mechanisms are needed. it is clear that these newly synthesized compounds provide a new rationale for anti-CN drugs, with fewer side-effects than the methemoglobin formers.
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Harrison JR, O’Brien P, Porter DW, Smith NM. Studies towards the preparation of sparteine-like diamines for asymmetric synthesis †. ACTA ACUST UNITED AC 1999. [DOI: 10.1039/a906969k] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Shi X, Flynn DC, Porter DW, Leonard SS, Vallyathan V, Castranova V. Efficacy of taurine based compounds as hydroxyl radical scavengers in silica induced peroxidation. ANNALS OF CLINICAL AND LABORATORY SCIENCE 1997; 27:365-74. [PMID: 9303176] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
While it is widely believed that taurine may play an important role in protecting cells against toxic injury by functioning as an antioxidant, there is a lack of evidence to support this hypothesis. In this study, electron spin resonance (ESR) was used to investigate the reaction of taurine and hypotaurine with hydroxyl radicals (.OH). The Fenton reaction (Fe(II) + H2O2-->Fe(III) + .OH + OH-) and the Cr(V)-mediated Fenton-like reaction (Cr(V) + H2O2-->Cr(VI) + .OH + OH-) were used as sources of .OH radicals. The results show that hypotaurine but not taurine effectively scavenges .OH radicals with a reaction rate constant of k = 1.6 x 10(10) M-1s-1. That is comparable with other efficient .OH radical scavengers. The effect of taurine and hypotaurine on silica-induced lipid peroxidation was evaluated using linoleic acid as a model lipid. Hypotaurine, but not taurine, caused a significant inhibition of silica-induced lipid peroxidation. The results show that hypotaurine is an excellent antioxidant and appears to have the potential for being a therapeutic agent against silica-induced lung injury.
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Porter DW, Yakushiji H, Nakabeppu Y, Sekiguchi M, Fivash MJ, Kasprzak KS. Sensitivity of Escherichia coli (MutT) and human (MTH1) 8-oxo-dGTPases to in vitro inhibition by the carcinogenic metals, nickel(II), copper(II), cobalt(II) and cadmium(II). Carcinogenesis 1997; 18:1785-91. [PMID: 9328176 DOI: 10.1093/carcin/18.9.1785] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The toxicity of Ni(II), Co(II) and Cu(II) in animals, and that of Cd(II) in cultured cells, has been associated with generation of the promutagenic lesion 8-oxo-7,8-dihydroguanine (8-oxoguanine) in DNA, among other effects. One possible source of this base may be 8-oxo-7,8-dihydro-2'-deoxyguanosine-5'-triphosphate (8-oxo-dGTP), a product of oxidative damage to the nucleotide pool, from which it is incorporated into DNA. To promote such incorporation, the metals would have to inhibit specific cellular 8-oxo-dGTPases that eliminate 8-oxo-dGTP from the nucleotide pool. The present study was designed to test such inhibition in vitro on 8-oxo-dGTPases from two different species, the human MTH1 protein and Escherichia coli MutT protein. In the presence of Mg(II), the natural activator of 8-oxo-dGTPases, all four metals were found to inhibit both enzymes. For MTH1, the IC50 values (+/- SE; n = 3-4) were 17 +/- 2 microM for Cu(II), 30 +/- 8 microM for Cd(II), 376 +/- 71 microM for Co(II) and 801 +/- 97 microM for Ni(II). For MutT, they were 60 +/- 6 microM for Cd(II), 102 +/- 8 microM for Cu(II), 1461 +/- 96 microM for Ni(II) and 8788 +/- 1003 microM for Co(II). Thus, Cu(II) and Cd(II) emerged as much stronger inhibitors than Ni(II) and Co(II), and MTH1 appeared to be generally more sensitive to metal inhibition than MutT. Interestingly, in the absence of Mg(II), the activity of the enzymes could be restored by Co(II) to 73% of that with Mg(II) alone for MutT, and 34% for MTH1, the other metals being much less or non-effective. The difference in sensitivity to metal inhibition between the two enzymes may reflect the differences in the amino acid ligands, especially the cysteine ligand, outside their evolutionarily conserved Mg(II)-binding active sites, which might indicate predominantly non-competitive or uncompetitive mechanism of the inhibition. The overall results suggest that inhibition of 8-oxo-dGTPases may be involved in the mechanisms of induction of the 8-oxoguanine lesion in DNA by the metal ions studied, especially the non-redox-active Cd(II) cation.
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Porter DW, Nelson VC, Fivash MJ, Kasprzak KS. Mechanistic studies of the inhibition of MutT dGTPase by the carcinogenic metal Ni(II). Chem Res Toxicol 1996; 9:1375-81. [PMID: 8951243 DOI: 10.1021/tx9600816] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Promutagenic 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxo-dG) levels are increased in DNA of animals exposed to carcinogenic metals, such as Ni(II). Besides being generated directly in genomic DNA, 8-oxo-dG may be incorporated there from 8-oxo-7,8-dihydro-2'-deoxyguanosine 5'-triphosphate (8-oxo-dGTP), a product of oxidative damage to the nucleotide pool. The Escherichia coli dGTPase MutT, and analogous dGTPases in rats and humans, have been suggested as a defense against such incorporation because they hydrolyze 8-oxo-dGTP to 8-oxo-7,8-dihydro-2'-deoxyguanosine 5'-monophosphate (8-oxo-dGMP). MutT and its mammalian counterparts are Mg(II)-dependent enzymes. Ni(II), in turn, is known to interact antagonistically with Mg(II) in biological systems. Thus, we hypothesized that Ni(II) might inhibit the activity of MutT. As an initial examination of this hypothesis, we conducted enzyme kinetic studies of MutT to determine the effect of Ni(II) on MutT activity and the mechanisms involved. As found, Ni(II) inhibited MutT in a concentration-dependent manner when either dGTP or 8-oxo-dGTP was the nucleotide substrate. Ni(II) was determined to be an uncompetitive inhibitor of MutT with respect to Mg(II) when dGTP was the substrate, with apparent Ki of 1.2 mM Ni(II), and a noncompetitive inhibitor with respect to Mg(II) when 8-oxo-dGTP was the substrate, with apparent Ki of 0.9 mM Ni(II). Hence, the two metal cations did not compete with each other for binding at the MutT active site. This makes it difficult to predict Ni(II) effects on 8-oxo-dGTPases of other species. However, based upon the amino acid sequences of human and rat MutT-like dGTPases, their capacity for Ni(II) binding should be greater than that of MutT. Whether this could lead to stronger inhibition of those enzymes by Ni(II), or not, remains to be investigated.
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