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Archives of Toxicology (v.79, #12)
Intravenous exposure to di(2-ethylhexyl)phthalate (DEHP): metabolites of DEHP in urine after a voluntary platelet donation by Holger M. Koch; Hermann M. Bolt; Ralf Preuss; Reinhold Eckstein; Volker Weisbach; Jürgen Angerer (pp. 689-693).
In this study we investigated human metabolism and excretion of DEHP after intravenous exposure. For this purpose we determined the five major DEHP metabolites in urine samples of a volunteer before and after a platelet donation (dual-needle technique). Plateletpheresis procedures are known to cause a significant DEHP exposure. We observed a sharp increase in urinary DEHP metabolite concentrations after the procedure. Maximum concentrations of 5OH-MEHP, 5oxo-MEHP, 5cx-MEPP and MEHP observed 4 h after the procedure were 822, 729, 577 and 388 μg/l respectively. 2cx-MMHP was excreted at highest concentrations after 8 h (201 μg/l). Due to longer elimination half-times, 5cx-MEPP and 2cx-MMHP were the major metabolites excreted in urine 24 h after the exposure. The 24-h-cumulative excretion of 363 μg 5cx-MEPP, 353 μg 5OH-MEHP, 309 μg 5oxo-MEHP, 178 μg MEHP and 133 μg 2cx-MMHP indicates an absolute exposure of our volunteer of about 2.6 mg DEHP. Related to the body weight this equals a dose of 31.6 μg/kg body weight/day. This indicates that current risk or preventive limit values for DEHP such as the RfD of the US EPA (20 μg/kg/day) and the TDI of the European Union (20–48 μg/kg/day) can be exceeded on the day of the plateletpheresis. The amount of the dose excreted in urine, distribution of the metabolites in urine and all other elimination characteristics after intravenous DEHP exposure are comparable to oral exposure. There are no indications that toxicokinetic behaviour and the toxicity of DEHP are fundamentally different after the two routes of exposure. Therefore, toxicological endpoints observed for DEHP after oral application should also be considered relevant for medical procedures causing intravenous DEHP exposure, like apheresis procedures. Especially women in their reproductive age need to be protected from DEHP exposures exceeding the above mentioned preventive limit values.
Keywords: Metabolism; Human; Intravenous; Exposure; Apheresis; Plateletpheresis; Di(2-ethylhexyl)phthalate (DEHP); Mono(2-ethyl-5-hydroxyhexyl)phthalate (5OH-MEHP); Mono(2-ethyl-5-oxo-hexyl)phthalate (5oxo-MEHP); Mono(2-ethyl-5-carboxypropyl)phthalate (5cx-MEPP); Mono[2-(carboxymethyl)hexyl]phthalate (2cx-MMHP); Mono(2-ethylhexyl)phthalate (MEHP)
Intravenous exposure to di(2-ethylhexyl)phthalate (DEHP): metabolites of DEHP in urine after a voluntary platelet donation by Holger M. Koch; Hermann M. Bolt; Ralf Preuss; Reinhold Eckstein; Volker Weisbach; Jürgen Angerer (pp. 689-693).
In this study we investigated human metabolism and excretion of DEHP after intravenous exposure. For this purpose we determined the five major DEHP metabolites in urine samples of a volunteer before and after a platelet donation (dual-needle technique). Plateletpheresis procedures are known to cause a significant DEHP exposure. We observed a sharp increase in urinary DEHP metabolite concentrations after the procedure. Maximum concentrations of 5OH-MEHP, 5oxo-MEHP, 5cx-MEPP and MEHP observed 4 h after the procedure were 822, 729, 577 and 388 μg/l respectively. 2cx-MMHP was excreted at highest concentrations after 8 h (201 μg/l). Due to longer elimination half-times, 5cx-MEPP and 2cx-MMHP were the major metabolites excreted in urine 24 h after the exposure. The 24-h-cumulative excretion of 363 μg 5cx-MEPP, 353 μg 5OH-MEHP, 309 μg 5oxo-MEHP, 178 μg MEHP and 133 μg 2cx-MMHP indicates an absolute exposure of our volunteer of about 2.6 mg DEHP. Related to the body weight this equals a dose of 31.6 μg/kg body weight/day. This indicates that current risk or preventive limit values for DEHP such as the RfD of the US EPA (20 μg/kg/day) and the TDI of the European Union (20–48 μg/kg/day) can be exceeded on the day of the plateletpheresis. The amount of the dose excreted in urine, distribution of the metabolites in urine and all other elimination characteristics after intravenous DEHP exposure are comparable to oral exposure. There are no indications that toxicokinetic behaviour and the toxicity of DEHP are fundamentally different after the two routes of exposure. Therefore, toxicological endpoints observed for DEHP after oral application should also be considered relevant for medical procedures causing intravenous DEHP exposure, like apheresis procedures. Especially women in their reproductive age need to be protected from DEHP exposures exceeding the above mentioned preventive limit values.
Keywords: Metabolism; Human; Intravenous; Exposure; Apheresis; Plateletpheresis; Di(2-ethylhexyl)phthalate (DEHP); Mono(2-ethyl-5-hydroxyhexyl)phthalate (5OH-MEHP); Mono(2-ethyl-5-oxo-hexyl)phthalate (5oxo-MEHP); Mono(2-ethyl-5-carboxypropyl)phthalate (5cx-MEPP); Mono[2-(carboxymethyl)hexyl]phthalate (2cx-MMHP); Mono(2-ethylhexyl)phthalate (MEHP)
Gaseous nitrogen oxide repressed benzo[a]pyrene-induced human lung fibroblast cell apoptosis via inhibiting JNK1 signals by Jing-Hsien Chen; Fen-Pi Chou; Hui-Hsuan Lin; Chau-Jong Wang (pp. 694-704).
Benzo[a]pyrene (B[a]P) is present in environmental pollution and cigarette smoke. B[a]P has been shown to induce apoptosis in hepatoma cells, human B cells, human ectocervical cells, macrophages, and rat lungs. Nitrogen oxides (NOx) are the other important indoor and outdoor air pollutants. Many studies have indicated that NO gas causes lung tissue damage both by its oxidative properties and free radicals. In our previous study we demonstrated that NO gas induced proliferation of human lung fibroblast MRC-5 cells. In this study we showed that NO gas inhibits B[a]P-induced MRC-5 cells apoptosis by cell cycle analysis. Western blot data revealed that NO gas increased the expressions of anti-apoptosis proteins (Bcl-2 and Mcl-1) and decreased the expression of apoptosis proteins (Bax, t-Bid, cytochrome c, FasL, and caspases) after B[a]P treatment. We further clarified that B[a]P-induced MRC-5 cell apoptosis via JNK1/FasL and JNK1/p53 signals. In conclusion, NO gas inhibited B[a]P-induced MRC-5 cells apoptosis via inhibition of JNK1 apoptosis pathway and induction of Bcl-2 and Mcl-1 anti-apoptosis pathway.
Keywords: Benzo[a]pyrene (B[a]P); Gaseous nitrogen oxide; JNK1; Anti-apoptosis
Gaseous nitrogen oxide repressed benzo[a]pyrene-induced human lung fibroblast cell apoptosis via inhibiting JNK1 signals by Jing-Hsien Chen; Fen-Pi Chou; Hui-Hsuan Lin; Chau-Jong Wang (pp. 694-704).
Benzo[a]pyrene (B[a]P) is present in environmental pollution and cigarette smoke. B[a]P has been shown to induce apoptosis in hepatoma cells, human B cells, human ectocervical cells, macrophages, and rat lungs. Nitrogen oxides (NOx) are the other important indoor and outdoor air pollutants. Many studies have indicated that NO gas causes lung tissue damage both by its oxidative properties and free radicals. In our previous study we demonstrated that NO gas induced proliferation of human lung fibroblast MRC-5 cells. In this study we showed that NO gas inhibits B[a]P-induced MRC-5 cells apoptosis by cell cycle analysis. Western blot data revealed that NO gas increased the expressions of anti-apoptosis proteins (Bcl-2 and Mcl-1) and decreased the expression of apoptosis proteins (Bax, t-Bid, cytochrome c, FasL, and caspases) after B[a]P treatment. We further clarified that B[a]P-induced MRC-5 cell apoptosis via JNK1/FasL and JNK1/p53 signals. In conclusion, NO gas inhibited B[a]P-induced MRC-5 cells apoptosis via inhibition of JNK1 apoptosis pathway and induction of Bcl-2 and Mcl-1 anti-apoptosis pathway.
Keywords: Benzo[a]pyrene (B[a]P); Gaseous nitrogen oxide; JNK1; Anti-apoptosis
2,4,6-Trinitrotoluene inhibits endothelial nitric oxide synthase activity and elevates blood pressure in rats by Yang Sun; Motoyuki Iemitsu; Nobutake Shimojo; Takashi Miyauchi; Masahiro Amamiya; Daigo Sumi; Toshio Hayashi; Guifan Sun; Nobuhiro Shimojo; Yoshito Kumagai (pp. 705-710).
2,4,6-Trinitrotoluene (TNT), which is widely used in explosives, is an important occupational and environmental pollutant. Human exposure to TNT has been reported to be associated with cardiovascular dysfunction, but the mechanism is not well understood. In this study, we examine the endothelial nitric oxide synthase (eNOS) activity and blood pressure value following TNT exposure. With a crude enzyme preparation, we found that TNT inhibited the enzyme activity of eNOS in a concentration-dependent manner (IC50 value=49.4 μM). With an intraperitoneal administration of TNT (10 and 30 mg/kg) to rats, systolic blood pressure was significantly elevated 1 h after TNT exposure (1.2- and 1.3-fold of that of the control, respectively). Under the conditions, however, experiments with the inducible NOS inhibitor aminoguanidine revealed that an adaptive response against hypertension caused by TNT occurs. These results suggest that TNT is an environmental chemical that acts as an uncoupler of constitutive NOS isozymes, resulting in decreased nitric oxide formation associated with hypertension in rats.
Keywords: 2,4,6-Trinitrotoluene; Nitric oxide; Endothelial nitric oxide synthase; Blood pressure
2,4,6-Trinitrotoluene inhibits endothelial nitric oxide synthase activity and elevates blood pressure in rats by Yang Sun; Motoyuki Iemitsu; Nobutake Shimojo; Takashi Miyauchi; Masahiro Amamiya; Daigo Sumi; Toshio Hayashi; Guifan Sun; Nobuhiro Shimojo; Yoshito Kumagai (pp. 705-710).
2,4,6-Trinitrotoluene (TNT), which is widely used in explosives, is an important occupational and environmental pollutant. Human exposure to TNT has been reported to be associated with cardiovascular dysfunction, but the mechanism is not well understood. In this study, we examine the endothelial nitric oxide synthase (eNOS) activity and blood pressure value following TNT exposure. With a crude enzyme preparation, we found that TNT inhibited the enzyme activity of eNOS in a concentration-dependent manner (IC50 value=49.4 μM). With an intraperitoneal administration of TNT (10 and 30 mg/kg) to rats, systolic blood pressure was significantly elevated 1 h after TNT exposure (1.2- and 1.3-fold of that of the control, respectively). Under the conditions, however, experiments with the inducible NOS inhibitor aminoguanidine revealed that an adaptive response against hypertension caused by TNT occurs. These results suggest that TNT is an environmental chemical that acts as an uncoupler of constitutive NOS isozymes, resulting in decreased nitric oxide formation associated with hypertension in rats.
Keywords: 2,4,6-Trinitrotoluene; Nitric oxide; Endothelial nitric oxide synthase; Blood pressure
Effects of interleukins 2 and 12 on the levels of granzyme B and perforin and their mRNAs in tributyltin-exposed human natural killer cells by LeeShawn D. Thomas; Hemangini Shah; Arthur D. Bankhurst; Margaret M. Whalen (pp. 711-720).
Natural killer (NK) cells are a subset of lymphocytes that are capable of killing tumor cells, virally infected cells and antibody coated cells. Tributyltin (TBT) is a toxic chemical used for various industrial purposes such as: slime control in paper mills, disinfection of circulating industrial cooling waters, anti-fouling agents, and the preservation of wood. TBT can be found in edible items such as fish. A previous study showed that a 1 h exposure of NK cells to TBT caused persistent inhibition of NK-cell ability to destroy tumor cells in the 24 and 48 h periods following exposure and that this loss of function could be significantly prevented and/or reversed if the NK-stimulatory interleukins (IL) 2 or 12 were present during the 24 and 48 h periods. We had also shown that TBT exposure was able to significantly decrease the protein and mRNA levels of the cytotoxic proteins, granzyme B and perforin, and the phosphorylation of cAMP-response-element-binding protein (CREB) under these conditions. In this study we address the effects of IL-2 and IL-12 on the TBT-induced decreases in NK-cell levels of the cytotoxic proteins, their mRNAs, and CREB phosphorylation. IL-2 appeared to prevent/reverse TBT-induced declines in perforin protein levels and the mRNA for perforin seen in the 24 h period following a 1 h exposure to 300 nM TBT. However, the TBT-induced decreases in the levels of perforin and perforin mRNA seen in the 48 h period following a 1 h exposure to TBT were not statistically significantly prevented/reversed by IL-2. Additionally, the TBT-induced decreases in granzyme B, granzyme B mRNA, and CREB phosphorylation were not statistically significantly reversed by either IL-2 or IL-12 after 24 or 48 h.
Keywords: Butyltins; Granzyme B; Perforin; IL-2; IL-12
Effects of interleukins 2 and 12 on the levels of granzyme B and perforin and their mRNAs in tributyltin-exposed human natural killer cells by LeeShawn D. Thomas; Hemangini Shah; Arthur D. Bankhurst; Margaret M. Whalen (pp. 711-720).
Natural killer (NK) cells are a subset of lymphocytes that are capable of killing tumor cells, virally infected cells and antibody coated cells. Tributyltin (TBT) is a toxic chemical used for various industrial purposes such as: slime control in paper mills, disinfection of circulating industrial cooling waters, anti-fouling agents, and the preservation of wood. TBT can be found in edible items such as fish. A previous study showed that a 1 h exposure of NK cells to TBT caused persistent inhibition of NK-cell ability to destroy tumor cells in the 24 and 48 h periods following exposure and that this loss of function could be significantly prevented and/or reversed if the NK-stimulatory interleukins (IL) 2 or 12 were present during the 24 and 48 h periods. We had also shown that TBT exposure was able to significantly decrease the protein and mRNA levels of the cytotoxic proteins, granzyme B and perforin, and the phosphorylation of cAMP-response-element-binding protein (CREB) under these conditions. In this study we address the effects of IL-2 and IL-12 on the TBT-induced decreases in NK-cell levels of the cytotoxic proteins, their mRNAs, and CREB phosphorylation. IL-2 appeared to prevent/reverse TBT-induced declines in perforin protein levels and the mRNA for perforin seen in the 24 h period following a 1 h exposure to 300 nM TBT. However, the TBT-induced decreases in the levels of perforin and perforin mRNA seen in the 48 h period following a 1 h exposure to TBT were not statistically significantly prevented/reversed by IL-2. Additionally, the TBT-induced decreases in granzyme B, granzyme B mRNA, and CREB phosphorylation were not statistically significantly reversed by either IL-2 or IL-12 after 24 or 48 h.
Keywords: Butyltins; Granzyme B; Perforin; IL-2; IL-12
The local lymph node assay being too sensitive? by Vohr Hans-Werner; Ahr Hans Jürgen (pp. 721-728).
The local lymph node assay (LLNA) and modifications thereof were recently recognized by the OECD as stand-alone methods for the detection of skin-sensitizing potential. However, although the validity of the LLNA was acknowledged by the ICCVAM, attention was drawn to one major problem, i.e., the possibility of false positive results caused by non-specific cell activation as a result of inflammatory processes in the skin (irritation). This is based on the fact that inflammatory processes in the skin may lead to non-specific activation of dendritic cells, cell migration and non-specific proliferation of lymph node cells. Measuring cell proliferation by radioactive or non-radioactive methods, without taking the irritating properties of test items into account, leads thus to false positive reactions. In this paper, we have compared both endpoints: (1) cell proliferation alone and (2) cell proliferation in combination with inflammatory (irritating) processes. It turned out that a considerable number of tests were “false positive” to the definition mentioned above. By excluding such false positive results the LLNA seems not to be more sensitive than relevant guinea pig assays. These various methods and results are described here.
Keywords: LLNA; IMDS; Guinea pig assay; Irritation; Sensitization
The local lymph node assay being too sensitive? by Vohr Hans-Werner; Ahr Hans Jürgen (pp. 721-728).
The local lymph node assay (LLNA) and modifications thereof were recently recognized by the OECD as stand-alone methods for the detection of skin-sensitizing potential. However, although the validity of the LLNA was acknowledged by the ICCVAM, attention was drawn to one major problem, i.e., the possibility of false positive results caused by non-specific cell activation as a result of inflammatory processes in the skin (irritation). This is based on the fact that inflammatory processes in the skin may lead to non-specific activation of dendritic cells, cell migration and non-specific proliferation of lymph node cells. Measuring cell proliferation by radioactive or non-radioactive methods, without taking the irritating properties of test items into account, leads thus to false positive reactions. In this paper, we have compared both endpoints: (1) cell proliferation alone and (2) cell proliferation in combination with inflammatory (irritating) processes. It turned out that a considerable number of tests were “false positive” to the definition mentioned above. By excluding such false positive results the LLNA seems not to be more sensitive than relevant guinea pig assays. These various methods and results are described here.
Keywords: LLNA; IMDS; Guinea pig assay; Irritation; Sensitization
Molecular mechanism on the testicular toxicity of 1,3-dinitrobenzene in Sprague-Dawley rats: preliminary study by Masako Muguruma; Masaki Yamazaki; Miwa Okamura; Mitsuyoshi Moto; Yoko Kashida; Kunitoshi Mitsumori (pp. 729-736).
The present study was conducted to elucidate the possible molecular mechanism of germinal cell apoptosis induced by Sertoli cell damage after 1,3-dinitrobenzene (1,3-DNB), a testicular toxicant, was administered to laboratory male rats. In this study, male Sprague-Dawley rats were administered with a single oral dose of 1,3-DNB (25 mg/kg body weight). Histopathological examinations and TUNEL methods revealed a marked increase in the number of apoptotic pachytene spermatocytes in seminiferous tubules showing stages VII–VIII and IX–XI of the spermatogenic cycle at 24 h after 1,3-DNB treatment. In immunohistochemical analysis, the cytoplasm and nuclei of pachytene spermatocytes were sometimes stained with antibodies to Bax and cleaved caspase-3 at 24 h after treatment. RT-PCR analysis for apoptosis-related gene expression showed that the expression of Bax,Bcl-2, Bcl-xL, and Bcl-xs genes, which are implicated in mitochondrial pathway, was significantly upregulated in the testes of the treated rats. These results suggest that the mitochondrial pathway is mainly involved in the testicular germinal cell apoptosis in rats induced by 1,3-DNB.
Keywords: 1,3-dinitrobenzene; Testicular toxicity; Germ cell apoptosis; Rat
Molecular mechanism on the testicular toxicity of 1,3-dinitrobenzene in Sprague-Dawley rats: preliminary study by Masako Muguruma; Masaki Yamazaki; Miwa Okamura; Mitsuyoshi Moto; Yoko Kashida; Kunitoshi Mitsumori (pp. 729-736).
The present study was conducted to elucidate the possible molecular mechanism of germinal cell apoptosis induced by Sertoli cell damage after 1,3-dinitrobenzene (1,3-DNB), a testicular toxicant, was administered to laboratory male rats. In this study, male Sprague-Dawley rats were administered with a single oral dose of 1,3-DNB (25 mg/kg body weight). Histopathological examinations and TUNEL methods revealed a marked increase in the number of apoptotic pachytene spermatocytes in seminiferous tubules showing stages VII–VIII and IX–XI of the spermatogenic cycle at 24 h after 1,3-DNB treatment. In immunohistochemical analysis, the cytoplasm and nuclei of pachytene spermatocytes were sometimes stained with antibodies to Bax and cleaved caspase-3 at 24 h after treatment. RT-PCR analysis for apoptosis-related gene expression showed that the expression of Bax,Bcl-2, Bcl-xL, and Bcl-xs genes, which are implicated in mitochondrial pathway, was significantly upregulated in the testes of the treated rats. These results suggest that the mitochondrial pathway is mainly involved in the testicular germinal cell apoptosis in rats induced by 1,3-DNB.
Keywords: 1,3-dinitrobenzene; Testicular toxicity; Germ cell apoptosis; Rat