* Department of Environmental Sciences and Engineering, School of Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7400;
National Exposure Research Laboratory, U.S. Environmental Protection Agency, MD-44, Research Triangle Park, North Carolina 27711; and
Department of Biostatistics, School of Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-7400
Received November 15, 2001; accepted April 5, 2002
![]() |
ABSTRACT |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Key Words: naphthalene-1,2-oxide; 1,2-naphthoquinone; 1,4-naphthoquinone; tumorigenicity; rat; hemoglobin; albumin.
![]() |
INTRODUCTION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
The acute effects of human exposure to naphthalene include hemolytic anemia (Santhanakrishnan et al., 1973) and cataracts (van Heyningen and Pirie, 1967
). Rodents are less susceptible to naphthalenes hemolytic effects (Shopp et al., 1984
), but cataracts have been seen in rats exposed to naphthalene (van Heyningen, 1979
). Moreover, rodents are susceptible to respiratory toxicity of naphthalene, including nasal adenomas in rats (NTP, 2000
), necrosis of pulmonary bronchiolar epithelial cells in mice (Plopper et al., 1992
), and pulmonary alveolar/bronchiolar adenomas in female mice (Abdo et al., 1992
).
The species-specific toxicity of naphthalene has been attributed to differences in the site and rate of metabolism (OBrien et al., 1985), however, the ultimate toxic metabolites have not been conclusively identified. Naphthalene is initially metabolized to naphthalene-1,2-oxide (NPO) by P450 NADP(H)-dependent oxidation. Subsequent transformation of NPO yields 1-naphthol, 1,2-dihydro-1,2-dihydroxy-naphthalene, 1,2-naphthoquinone (1,2-NPQ), 1,4-naphthoquinone (1,4-NPQ), and various sulfate, glucuronide, and glutathione conjugates (NTP, 2000
). Although NPO has been implicated as the principal toxic metabolite in mouse lung Clara cells (Chichester et al., 1994) and rat lung (Sweeney et al., 1995
), 1,2-NPQ is also a major metabolite bound to cysteine residues in mouse lung Clara cells in vitro (Zheng et al., 1997
). In humans, 1,2-NPQ and 1,4-NPQ caused sister chromatid exchanges in lymphocytes and cytotoxicity to mononuclear leukocytes in vitro, but NPO did not demonstrate cytotoxic or genotoxic effects (Wilson et al., 1996
).
It is difficult to directly measure reactive electrophilic metabolites such as NPO, 1,2-NPQ and 1,4-NPQ in vivo, so we sought assays for protein adducts of these compounds. Our laboratory has previously investigated the use of cysteinyl adducts of hemoglobin (Hb) and albumin (Alb) to assess levels of the analogous benzene metabolites, i.e., benzene oxide (BO; Lindstrom et al., 1998, 1999
; Yeowell-OConnell et al., 1996
Yeowell-OConnell et al., 1998
), 1,2-benzoquinone (1,2-BQ), and 1,4-benzoquinone (1,4-BQ; Waidyanatha et al., 1998
). We extended these methods to measure cysteinyl adducts formed from reactions of NPO, 1,2-NPQ, and 1,4-NPQ with Hb and Alb (Fig. 1
; Waidyanatha et al., in press
). Using this assay, we demonstrated that these Hb and Alb adducts of NPO, 1,2-NPQ, and 1,4-NPQ increased with dose following a single administration of 0800 mg naphthalene per kg body weight in F344 rats (Waidyanatha et al., in press
).
|
![]() |
MATERIALS AND METHODS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Caution: TFAA reacts violently with water and should only be used to derivatize proteins that are completely dry.
Animals and blood collection.
Forty-five male F344 rats (175200 g) were obtained from Charles River Breeding Laboratories (Raleigh, NC) and were housed in polycarbonate cages on a 12-h light/dark cycle for 2 weeks before use. Food and water were provided ad libitum. Corn oil only (vehicle control) was administered by gavage to 3 rats. The remaining 42 rats were divided into 2 groups of 21 animals, and a single po dose of either 400 or 800 mg naphthalene per kg body weight was administered (in corn oil) to each animal by gavage. The 400 mg/kg dose was chosen to allow comparison with the experiments conducted at the same dose by Cho et al., 1994. The 800 mg/kg dose was chosen to be 2-fold higher, but still well below the po LD50 (12.8 g/kg) of naphthalene in the rat (Papciak and Mallory, 1990). Three animals from each group were sacrificed at 1, 2, 7, 14, 21, 28, and 42 days following dosing. Rats were anesthetized with methoxyflurane and blood was removed by direct cardiac puncture into a heparinized syringe. Approximately 79 ml of blood were collected from each animal. Blood was stored on ice immediately, and plasma and red cell fractions were separated within 2 h.
Isolation and purification of Hb and Alb.
Blood samples were centrifuged at 800 x g for 15 min and the plasma layer was removed by pipet. The red blood cell layer was washed 3 times with an equal volume of 0.9% saline. The buffy coat was removed by pipet and an equal volume of deionized water was added to the red blood cells. Samples were frozen at -20°C to lyse cells prior to isolation of Hb.
Hb and Alb were isolated according to the procedure in Rappaport et al. (Rappaport et al., 1993) with modifications. Briefly, Hb was obtained from thawed, lysed red cells by centrifuging at 30,000 x g at 4°C for 40 min to remove the membranes. The supernatant was dialyzed (Spectra-Pore 1, 6000-8000 MWCO) against 4 x 3.5 l of deionized water at 4°C over 24 h (rather than by Sephadex chromatography). Globin was precipitated by dropwise addition of the dialysate to cold acidified acetone (0.1% hydrochloric acid by volume). The precipitate was washed with ice-cold acetone and dried to constant weight under vacuum at 37°C.
To isolate Alb, an equal volume of saturated aqueous ammonium sulfate was added to thawed pure plasma by dropwise addition. This mixture was centrifuged at 800 x g to remove immunoglobulins. The supernatant was dialyzed (Spectra-Pore 1, 12,000 MWCO) against 4 x 3.5 l of deionized water at 4°C over 24 h. The Alb solution was lyophilized to constant weight.
Measurement of NPO, 1,2-NPQ, and 1,4-NPQ adducts with Hb and Alb.
Cysteinyl adducts of NPO, 1,2-NPQ, and 1,4-NPQ with Hb and Alb were assayed with the method of Waidyanatha et al. (in press). Briefly, 100 µl of a 50 mg/ml solution of Hb or 50 µl of a 50 mg/ml solution of Alb were added to 5 µg of deuterium-labeled protein bound internal standard ([2H5]1,2-NPQ, [2H5]1,4-NPQ, [2H6]NPO-Alb). Samples were then dried in a vacuum oven at 80°C for several h. To the dried proteins, 750 µl of TFAA and 20 µl of methanesulfonic acid were added and the proteins were incubated at 100°C for 40 min to produce 1,2-NPQ-S-TFA, 1,4-NPQ-S-TFA, and 2 structural isomers of NPO-S-TFA (NPO1-S-TFA and NPO2-S-TFA; see Fig. 1). The samples were then cooled to room temperature and excess TFAA was removed under a stream of nitrogen. To each sample, 1 ml of hexane was added, followed by 1 ml of 0.1 M Tris buffer (pH 7.5). The mixture was vortexed for 30 s and then centrifuged. The hexane layer was removed and washed twice with 1 ml of deionized water. Samples were then concentrated to 200 µl and transferred to vials for GC-MS analysis. Standard curves for NPO and NPQ adducts were prepared by adding various amounts of a NPO1-NAC, NPO2-NAC, 1,2-NPQ-NAC, and 1,4-NPQ-NAC to 2.5 mg portions of untreated human Alb (Sigma) or 5 mg portions of untreated human Hb (Sigma) and then performing the assay as described above for the experimental samples.
GC/NICI-MS analysis.
All GC-MS analyses were conducted in negative-ion chemical ionization (NICI) mode using a Hewlett-Packard 5890 series II plus gas chromatograph equipped with a Hewlett-Packard 5989B MS engine. A DB-5 capillary column (60 m, 0.25-mm i.d, 0.25-µm phase thickness; J & W Scientific, Inc.) was used; 2-µl samples were injected in the splitless mode with a He carrier gas flow of 1.5 ml/min. Methane (source pressure of 2 Torr) was used as the chemical ionization reagent gas.
Analysis of NPO1-S-TFA and NPO2-S-TFA.
The injection port and source temperatures were 250 and 100°C, respectively. The oven temperature was held for 2 min at 75°C, then increased at 4°C/min to 160°C where it was held for 15 min, then increased at 50°C/min to 260°C where it was held for 15 min. The molecular ions of NPO1-S-TFA and NPO2-S-TFA (m/z 256) and [2H6]NPO1-S-TFA and [2H6]NPO2-S-TFA (m/z 263) were monitored using the selected ion monitoring mode as described in Waidyanatha et al. (in press).
Analysis of 1,2-NPQ-S-TFA and 1,4-NPQ-S-TFA.
The injection port and source temperatures were 250 and 150°C, respectively. For 1,2-NPQ-Alb, 1,4-NPQ-Alb and 1,4-NPQ-Hb, the oven temperature was held for 2 min at 75°C, then increased at 6°C/min to 150°C where it was held for 28 min, then increased at 50°C/min to 260°C where it was held for 15 min. For 1,2-NPQ-Hb, the oven temperature was held for 2 min at 75°C, then increased at 6°C/min to 145°C where it was held for 35 min, then increased at 50°C/min to 260°C where it was held for 10 min. The molecular ions of 1,2-NPQ-S-TFA and 1,4-NPQ-S-TFA (m/z 383) and [2H5]1,2-NPQ-S-TFA and [2H5]1,4-NPQ-S-TFA (m/z 388) were monitored using the selected ion monitoring mode.
Statistical analysis.
All statistical analyses were conducted using SAS Statistical Software (Cary, NC). Data obtained prior to peak adduct levels were excluded from linear and nonlinear regression analyses. After peak adduct levels have been obtained, it can be assumed that adduct formation does not significantly contribute to changes in adduct concentration and that the rate of change of adduct concentration is a function of adduct removal only. Standard errors were estimated for all parameters.
Estimation of rates of adduct elimination and adduct instability.
Rates of elimination and instability of Alb and Hb adducts were estimated as described in Troester et al. (2000, 2001), respectively. We define A(t) = [RY]/[Y] as the amount of adduct RY (nmol) per g of protein (i.e., NPO1-Y, NPO2-Y, 1,2-NPQ-Y, or 1,4-NPQ-Y for Y = Hb or Alb) at some time t (d) after administration of naphthalene. Because the turnover rates of Alb and Hb follow different kinetics, they were modeled differently as described below.
Alb adducts.
Following a single dose of naphthalene, Alb adducts are eliminated by first-order kinetics according to the following expression:
![]() | ((1)) |
![]() | ((2)) |
![]() | ((3)) |
Independent estimates of k' were obtained for each Alb adduct in rats following administration of either 400 or 800 mg naphthalene per kg body weight. To determine whether k' differed between the 2 dose groups, a 95% confidence interval for the difference between the two estimates of k' was calculated using the multiple regression model:
![]() | ((4)) |
![]() | ((5)) |
![]() | ((6)) |
Hb adducts.
Following a single dose of naphthalene, the elimination of Hb adducts can be described by mixed zero- and first-order kinetics according to:
![]() | ((7)) |
![]() | ((8)) |
Iterations were conducted 4 times for NPO1-Hb adducts and 5 times for NPO2-Hb (with t recalculated using Equation 8
after each iteration); the last two iterations in each case yielded identical estimates and confidence intervals for A0 and k.
The value of ter was specified a priori using strain-specific estimates of ter for the F344 rat (Derelanko, 1987). The estimate of ter for F344 rats is associated with some uncertainty, so nonlinear regression using the approach above was conducted using the point estimate of ter (66 days) for the strain, as well as both the upper and lower 95% confidence interval values for ter (62 days and 70 days, respectively).
In these experiments, the concentration of Hb adducts was followed for 6 weeks following administration. As young animals increase in size, their blood volume increases proportionally and can dilute Hb adducts (Osterman-Golkar et al., 1999). In our study, animals increased in body weight from 261 g (SE = 2.9 g, n = 6) at dosing to 301 g (SE = 3.7 g, n = 6) 42 days after dosing. Thus, for regression of Hb adducts via Equation 7
, the body-weight (b.w.) adjusted adduct level [A(t)adj in nmol/g] was calculated according to the following relationship (Troester et al., 2001
):
![]() | ((9)) |
![]() |
RESULTS |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
|
|
|
|
|
|
|
|
![]() |
DISCUSSION |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
The first-order rate constants (k') for adduct turnover indicate that NPO-Alb is more stable than NPQ-Alb. This is consistent with results from a similar stability study involving cysteinyl Hb and Alb adducts of BO and 1,4-BQ (only the mono-S-substituted adduct was measured), where BO-Alb was more stable than 1,4-BQ-Alb (Troester et al., 2000). In that study, we speculated that glutathione or other protein sulfhydryls react with the mono-S-substituted 1,4-BQ-Alb to form a multi-S-substituted adduct, accounting for the apparent instability. (Previous studies have shown that chemical oxidation of hydroquinone [HQ] in the presence of glutathione results in multi-S-substituted conjugates [Eckert et al., 1990
, Lau et al., 1988
], and multi-S-substituted conjugates of HQ have been identified as in vivo metabolites of HQ [Hill et al., 1993
].)
However, if reactivity of the quinones were solely responsible for the instability of quinone-protein adducts, we would expect NPQ adducts to be more stable than the corresponding BQ adducts. That is, Michael addition occurs at the ß position of an , ß-unsaturated ketone due to a partial positive charge at that position, which diminishes as the number of aromatic rings increases because of delocalization of electron density. The oxidation potentials of NPQs are also expected to be decreased relative to BQs, due to greater delocalization of the unpaired electron in the ortho-semiquinone radical associated with the larger ring system (McCoull et al., 1999
). Previous studies have shown that the rate of nucleophilic addition is slower with the ortho-quinone of benzo[a]pyrene than with 1,2-NPQ (Murty and Penning, 1992
). To the contrary, we observed a turnover rate for 1,2-NPQ-Alb (Table 2
) more than twice that of 1,4-BQ-Alb (half-life of 2.5 days [Troester et al., 2000
]), and the elimination of 1,4-NPQ-Alb (Fig. 3
) appears to be even faster. At present, very little is understood about how structural characteristics of bound metabolites influence the stability of protein adducts.
The NPO-Alb adducts also appeared to be less stable than BO-Alb adducts (' = 0.225 d-1,
1/2 = 3.1 d [Troester et al., 2000
]). NPO-Alb adducts were turned over with first-order rate constants that ranged from 0.30 to 0.38 d-1 (Table 1
). Assuming that the BO-Alb represents a stable adduct, then
Alb = 0.23 d-1 in the particular F344 rats used in our studies, from which we estimate 0.07
0.15 d-1 for NPO-Alb (Equation 3
). Interestingly, this range of
for NPO-Alb is not consistent with values predicted for NPO-Hb (Table 4
), which indicated no evidence of instability in vivo. This is not the first study to demonstrate a lack of agreement between the stability of Hb and Alb adducts (e.g. ortho-toluidine [DeBord et al., 1992
], benzo[a]pyrenediolepoxide [Viau et al., 1993
], and naphthalene [Cho et al., 1994
]), although these previous studies did not characterize metabolite- and amino acid-specific adducts.
To our knowledge, the dose-dependence of protein adduct stability has not been tested previously. In this study, the dose of naphthalene did not appear to have a significant effect on the stability of naphthalene-derived Alb adducts. Statistical comparisons of the rate constants obtained for NPO-Alb, 1,2-NPQ-Alb, and 1,4-NPQ-Alb at 2 different doses (400 mg/kg and 800 mg/kg) demonstrated no significant difference in adduct stability.
NPO1-Hb adducts were only slightly unstable and NPO2-Hb adducts were stable following administration of 400 mg/kg naphthalene. However, the stability of NPO-Hb could not be investigated following an 800 mg/kg dose of naphthalene due to high variability in adduct concentration among animals at each time point. We suspect that the variability that is apparent in Hb adduct concentration, but not Alb adduct concentration, is a result of the greater toxicity of naphthalene on the hematopoeitic (site of Hb production) system relative to the hepatic system (site of Alb production). Hematopoietic effects are common following administration of a wide variety of chemicals due to the involvement of several organs (including bone marrow, thymus, lymph nodes, spleen, liver, stomach, intestines, and kidney among others) in the production of red blood cells. Toxicity to any of these organs could alter the concentration of Hb or the lifetime of the red blood cell (ter), thereby increasing variability in adduct levels. In fact, naphthalene has been shown to cause hemolytic anemia in humans, though rodents may be less susceptible to these effects (NTP, 2000). Therefore, in spite of our inability to document instability of NPO-Hb following an 800 mg/kg dose, we suspect that these adducts will not be useful indicators of exposure at doses of naphthalene that induce acute toxicity.
It was once believed that only stable Hb and Alb adducts were useful for exposure assessment. More recently, relationships between unstable adducts and blood concentrations of electrophiles have been thoroughly described and equations have been published that require estimates of k to calculate the mean daily blood concentration of electrophile (Granath et al., 1992, Troester et al., 2001
). These equations account for differences in kAlb and ter between species, but the validity of these equations ultimately depends upon the assumption that k is similar across species. Direct estimates of k in humans are seldom available. In spite of the instability observed for some of the naphthalene-derived adducts, these adducts are still more persistent than the reactive electrophiles from which they are formed and are useful in estimating the systemic doses of these metabolites.
![]() |
ACKNOWLEDGMENTS |
---|
![]() |
NOTES |
---|
The research described in this document was supported in part by the U.S. Environmental Protection Agency. It has been subjected to Agency review and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.
![]() |
REFERENCES |
---|
![]() ![]() ![]() ![]() ![]() ![]() ![]() |
---|
Chichester, C. H., Philpot, R. M., Weir, A. J., Buckpitt, A. R., and Plopper, C. G. (1991). Characterization of the cytochrome P-450 monooxygenase system in nonciliated bronchiolar epithelial (Clara) cells isolated from mouse lung. Am. J. Respir. Cell Mol. Biol. 4, 179186.[ISI][Medline]
Cho, M., Jedrychoswki, R., Hammock, B., and Buckpitt, A. (1994). Reactive naphthalene metabolite binding to hemoglobin and albumin.Fundam. Appl. Toxicol. 22, 2633.[ISI][Medline]
Clark, C., Henderson, T., Royer, R., Brooks, A., McClellan, R., Marshall, W., and Naman, T. (1982). Mutagenicity of diesel exhaust particulate extracts: Influence of fuel composition in two diesel engines. Fundam. Appl. Toxicol. 2, 3843.[Medline]
Davidian, M., and Gilitinan, D. M. (1995). Nonlinear regression models for individual data. In Nonlinear Models for Repeated Measurement Data (D. M. Gilitinan, Ed.), pp. 1762. CRC Press, Boca Raton, FL.
DeBord, D. G., Swearengin, T. F., Cheever, K. L., Booth-Jones, A. D., and Wissinger, L. A. (1992). Binding characteristics of ortho-toluidine to rat hemoglobin and albumin. Arch. Toxicol. 66, 231236.[ISI][Medline]
Derelanko, M. J. (1987). Determination of erythrocyte life span in F-344, Wistar, and Sprague-Dawley Rats using a modification of the [3H]diisopropylfluorophosphate ([3H]DFP) method. Fundam. Appl. Toxicol. 9, 271276.[ISI][Medline]
Eckert, K. G., Eyer, P., Sonnenbichler, J., and Zetl, I. (1990). Activation and detoxification of aminophenols. III. Synthesis and structural elucidation of various glutathione addition products to 1,4-benzoquinone. Xenobiotica 20, 351361.[ISI][Medline]
Granath, F., Ehrenberg, L., and Törnqvist, M. (1992). Degree of alkylation of macromolecules in vivo from variable exposure. Mutat. Res. 284, 297306.[ISI][Medline]
Hill, B. A., Kleiner, H. E., Ryan, E. A., Dulik, D. M., Monks, T. J., and Lau, S. S. (1993). Identification of multi-S-substituted conjugates of hydroquinone by HPLC-coulometric electrode array analysis and mass spectroscopy. Chem. Res. Toxicol. 6, 459469.[ISI][Medline]
Lau, S. S., Hill, B. A., Highet, R. J., and Monks, T. J. (1988). Sequential oxidation and glutathione addition to 1,4-benzoquinone: Correlation of toxicity with increased glutathione substitution. Mol. Pharmacol. 34, 829836.[Abstract]
Lindstrom, A. B., Yeowell-OConnell, K., Waidyanatha, S., McDonald, T. A., Golding, B. T., and Rappaport, S. M. (1998). Formation of hemoglobin and albumin adducts of benzene oxide in mouse, rat, and human blood. Chem. Res. Toxicol. 11, 302310.[ISI][Medline]
Lindstrom, A. B., Yeowell-OConnell, K., Waidyanatha, S., McDonald, T. A., and Rappaport, S. M. (1999). Investigation of benzene oxide in bone marrow and other tissues of F344 rats following metabolism of benzene in vitro and in vivo. Chem. Biol. Interact. 122, 4158.[ISI][Medline]
McCoull, K. D., Rindgen, D., Blair, I. A., and Penning, T. M. (1999). Synthesis and characterization of polycyclic aromatic hydrocarbon o-quinone depurinating N7-guanine adducts. Chem. Res. Toxicol. 12, 237246.[ISI][Medline]
McDougal, J. N., Pollard, D. L., Weisman, W., Garrett, C. M., and Miller, T. E. (2000). Assessment of skin absorption and penetration of JP-8 jet fuel and its components. Toxicol. Sci. 55, 247255.
Murty, V. S., and Penning, T. M. (1992). Polycyclic aromatic hydrocarbon (PAH) ortho-quinone conjugate chemistry: Kinetics of thiol addition to PAH ortho-quinones and structures of thioether adducts of naphthalene-1,2-dione. Chem. Biol. Interact. 84, 169188.[ISI][Medline]
NTP (2000). NTP Technical Report on the Toxicology and Carcinogenesis Studies of Naphthalene in F344/N Rats (Inhalation Studies). National Toxicology Program. NIH Publication No. 014434.
OBrien, K. A., Smith, L. L., and Cohen, G. M. (1985). Differences in naphthalene-induced toxicity in the mouse and rat. Chem. Biol. Interact. 55, 109122.[ISI][Medline]
Osterman-Golkar, S., Perez, H. L., Csanady, G. A., Kessler, W., and Filser, J. G. (1999). Methods for monitoring of propylene oxide exposure in Fischer 344 rats. Toxicology 134, 18.[ISI][Medline]
Papciak R. J., and Mallory, V. T. (1990). Acute toxicological evaluation of naphthalene. J. Am. Coll. Toxicol. B Acute Toxic. Data 1, 1719.
Plopper, C. G., Suverkropp, C., Morin, D., Nishio, S., and Buckpitt, A. (1992). Relationship of cytochrome P-450 activity to Clara cell cytotoxicity. I. Histopathologic comparison of the respiratory tract of mice, rats and hamsters after parenteral administration of naphthalene. J. Pharmacol. Exp. Ther. 261, 353363.
Rappaport, S. M., Ting, D., Jin, Z., Yeowell-OConnell, K., Waidyanatha, S., and McDonald, T. (1993). Application of Raney nickel to measure adducts of styrene oxide with hemoglobin and albumin. Chem. Res. Toxicol. 6, 238244.
Sabbioni, G., Skipper, P. L., Buchi, G., and Tannenbaum, S. R. (1987). Isolation and characterization of the major serum albumin adduct formed by aflatoxin B1 in vivo in rats. Carcinogenesis 8, 819824.
Santhanakrishnan, B. R., Ranganathan, G., and Raju, V. B. (1973). Naphthalene induced haemolytic anaemia with haemoglobinuria.Indian J. Pediatr. 40, 195197.
Schmeltz, I., Tosk, J., and Hoffmann, D. (1976). Formation and determination of naphthalenes in cigarette smoke. Anal. Chem. 48, 645650.
Shopp, G. M., White, K. L., Jr., Holsapple, M. P., Barnes, D. W., Duke, S. S., Anderson, A. C., Condie, L. W., Jr., Hayes, J. R., and Borzelleca, J. F. (1984). Naphthalene toxicity in CD-1 mice: General toxicology and immunotoxicology. Fundam. Appl. Toxicol. 4, 406419.
Sweeney, L. M., Shuler, M. L., Babish, J. G., and Ghanem, A. (1995). A cell culture analogue of rodent physiology: Application to naphthalene toxicology. Toxicol. in Vitro 9, 307316.
Troester, M. A., Kupper, L. L., and Rappaport, S. M. (2001). Comparison of non-linear and linear models for estimating haemoglobin adduct stability. Biomarkers 6, 251261.
Troester, M. A., Lindstrom, A. B., Kupper, L. L., Waidyanatha, S., and Rappaport, S. M. (2000). Stability of hemoglobin and albumin adducts of benzene oxide and 1,4- benzoquinone after administration of benzene to F344 rats. Toxicol. Sci. 54, 8894.
van Heyningen, R. (1979). Naphthalene cataract in rats and rabbits: A resume. Exp. Eye Res. 28, 435439.
van Heyningen, R., and Pirie, A. (1967). The metabolism of naphthalene and its toxic effects on the eye. Biochem. J. 102, 842852.
Viau, C., Mercier, M., and Blondin, O. (1993). Measurement of hemoglobin and albumin adducts of benzo[a]pyrenediolepoxide and their rate of elimination in the female Sprague-Dawley rat. Arch. Toxicol. 67, 468472.
Waidyanatha, S., Troester, M. A., Lindstrom, A. B., and Rappaport, S. M. (in press). Measurement of hemoglobin and albumin adducts of naphthalene-1,2-oxide, 1,2-naphthoquinone, and 1,4-naphthoquinone after administration of naphthalene to F344 rats. Chem. Biol. Interact.
Waidyanatha, S., Lin, P. H., and Rappaport, S. (1996). Characterization of chlorinated adducts of hemoglobin and albumin following administration of pentachlorophenol to rats. Chem. Res. Toxicol. 9, 647653.
Waidyanatha, S., Yeowell-OConnell, K., and Rappaport, S. M. (1998) A new assay for albumin and hemoglobin adducts of 1,2- and 1,4-benzoquinones. Chem. Biol. Interact. 115, 117139.
Wilson, A. S., Davis, C. D., Williams, D. P., Buckpitt, A. R., Pirmohamed, M., and Park, B. K. (1996). Characterisation of the toxic metabolite(s) of naphthalene. Toxicology 114, 233242.
Yeowell-OConnell, K., McDonald, T. A., and Rappaport, S. M. (1996). Analysis of hemoglobin adducts of benzene oxide by gas chromatography-mass spectrometry. Anal. Biochem. 237, 4955.
Yeowell-OConnell, K., Rothman, N., Smith, M. T., Hayes, R. B., Li, G., Waidyanatha, S., Dosemeci, M., Zhang, L., Yin, S., Titenko-Holland, N., and Rappaport, S. M. (1998). Hemoglobin and albumin adducts of benzene oxide among workers exposed to high levels of benzene. Carcinogenesis 19, 15651571.
Zheng, J., Cho, M., Jones, A. D., and Hammock, B. D. (1997). Evidence of quinone metabolites of naphthalene covalently bound to sulfur nucleophiles of proteins of murine Clara cells after exposure to naphthalene. Chem. Res. Toxicol. 10, 10081014.