Metabolism and Toxicity of Trichloroethylene and Tetrachloroethylene in Cytochrome P450 2E1 Knockout and Humanized Transgenic Mice.

Trichloroethylene (TCE) and tetrachloroethylene (PCE) are structurally similar olefins that can cause liver and kidney toxicity. Adverse effects of these chemicals are associated with metabolism to oxidative and glutathione conjugation moieties. It is thought that CYP2E1 is crucial to the oxidative metabolism of TCE and PCE, and may also play a role in formation of nephrotoxic metabolites; however, inter-species and inter-individual differences in contribution of CYP2E1 to metabolism and toxicity are not well understood. Therefore, the role of CYP2E1 in metabolism and toxic effects of TCE and PCE was investigated using male and female wild-type [129S1/SvlmJ], Cyp2e1(-/-), and humanized Cyp2e1 [hCYP2E1] mice. To fill in existing gaps in our knowledge, we conducted a toxicokinetic study of TCE (600 mg/kg, single dose, i.g.) and a subacute study of PCE (500 mg/kg/day, 5 days, i.g.) in 3 strains. Liver and kidney tissues were subject to profiling of oxidative and glutathione conjugation metabolites of TCE and PCE, as well as toxicity endpoints. The amounts of trichloroacetic acid formed in the liver was hCYP2E1≈ 129S1/SvlmJ > Cyp2e1(-/-) for both TCE and PCE; levels in males were about 2-fold higher than in females. Interestingly, 2- to 3-fold higher levels of conjugation metabolites were observed in TCE-treated Cyp2e1(-/-) mice. PCE induced lipid accumulation only in liver of 129S1/SvlmJ mice. In the kidney, PCE exposure resulted in acute proximal tubule injury in both sexes in all strains (hCYP2E1 ≈ 129S1/SvlmJ > Cyp2e1(-/-)). In conclusion, our results demonstrate that CYP2E1 is an important, but not exclusive actor in the oxidative metabolism and toxicity of TCE and PCE.

Nonalcoholic Fatty Liver Disease Is a Susceptibility Factor for Perchloroethylene-Induced Liver Effects in Mice.

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent pathological liver condition in developed countries. NAFLD results in severe alterations in liver function, including xenobiotic metabolism. Perchloroethylene (PERC) is a ubiquitous environmental pollutant, a known hepatotoxicant in rodents, and a probable human carcinogen. It is known that PERC disposition and metabolism are affected by NAFLD in mice; here, we examined how NAFLD changes PERC-associated liver effects. Male C57Bl6/J mice were fed a low-fat diet (LFD), high-fat diet (HFD), or methionine/folate/choline-deficient diet (MCD) to model a healthy liver, or mild and severe forms of NAFLD, respectively. After 8 weeks on diets, mice were orally administered PERC (300 mg/kg/day) or vehicle (5% aqueous Alkamuls-EL620) for 5 days. PERC-induced liver effects were exacerbated in both NAFLD groups. PERC exposure was associated with up-regulation of genes involved in xenobiotic, lipid, and glutathione metabolism, and down-regulation of the complement and coagulation cascades, regardless of the diet. Interestingly, HFD-fed mice, not MCD-fed mice, were generally more sensitive to PERC-induced liver effects. This was indicated by histopathology and transcriptional responses, where induction of genes associated with cell cycle and inflammation were prominent. Liver effects positively correlated with diet-specific differences in liver concentrations of PERC. We conclude that NAFLD alters the toxicodynamics of PERC and that NAFLD is a susceptibility factor that should be considered in future risk management decisions for PERC and other chlorinated solvents.

The Contribution of Peroxisome Proliferator-Activated Receptor Alpha to the Relationship Between Toxicokinetics and Toxicodynamics of Trichloroethylene.

Exposure to the ubiquitous environmental contaminant trichloroethylene (TCE) is associated with cancer and non-cancer toxicity in both humans and rodents. Peroxisome proliferator-activated receptor-alpha (PPARα) is thought to be playing a role in liver toxicity in rodents through activation of the receptor by the TCE metabolite trichloroacetic acid (TCA). However, most studies using genetically altered mice have not assessed the potential for PPARα to alter TCE toxicokinetics, which may lead to differences in TCA internal doses and hence confound inferences as to the role of PPARα in TCE toxicity. To address this gap, male and female wild type (129S1/SvImJ), Pparα-null, and humanized PPARα (hPPARα) mice were exposed intragastrically to 400 mg/kg TCE in single-dose (2, 5 and 12 h) and repeat-dose (5 days/week, 4 weeks) studies. Interestingly, following either a single- or repeat-dose exposure to TCE, levels of TCA in liver and kidney were lower in Pparα-null and hPPARα mice as compared with those in wild type mice. Levels of trichloroethanol (TCOH) were similar in all strains. TCE-exposed male mice consistently had higher levels of TCA and TCOH in all tissues compared with females. Additionally, in both single- and repeat-dose studies, a similar degree of induction of PPARα-responsive genes was observed in liver and kidney of hPPARα and wild type mice, despite the difference in hepatic and renal TCA levels. Additional sex- and strain-dependent effects were observed in the liver, including hepatocyte proliferation and oxidative stress, which were not dependent on TCA or TCOH levels. These data demonstrate that PPARα status affects the levels of the putative PPARα agonist TCA following TCE exposure. Therefore, interpretations of studies using Pparα-null and hPPARα mice need to consider the potential contribution of genotype-dependent toxicokinetics to observed differences in toxicity, rather than attributing such differences only to receptor-mediated toxicodynamic effects.

[Pulmonary alveolar proteinosis noted in a patient with thymoma].

A 74-year-old woman had general fatigue and mild fever in August 2004. Her chest X-ray showed slight ground glass opacities in the upper and middle lung fields of both lungs. Though she was prescribed antibacterial drugs, the abnormal shadows on chest X-ray did not improve. The chest CT showed ground glass opacities and reticular shadows with thickened alveolar septa (crazy-paving appearance) in both lungs, and a clearly defined mass in the anterior mediastinum. She underwent thymo-thymectomy with wedge resection of the upper lobe of the left lung. Anterior mediastinum tumor was pathologically diagnosed as thymoma. Lung biopsy demonstrated alveoli filled with SP-A positive granular materials, and we diagnosed pulmonary alveolar proteinosis. About 1 month after operation, the shadows on chest CT showed improvement. We think there might be some relationship between thymoma and pulmonary alveolar proteinosis.

Expression and transcriptional activity of alternative splice variants of Mitf exon 6.

Microphthalmia-associated transcription factor (Mitf) is a tissue-specific transcription factor. At least nine distinct mouse isoform mRNAs are encoded by alternative splicing of the first exon of Mitf (Mitf-A, -B, -C, -D, -E, -H, -J, -M, and -mc), while exons 2-9 of all Mitf isoforms examined to date are identical. In addition, alternative splice variants of exon 6a encoding 6 amino acid proximal to the basic region of the protein are known in Mitf-A, -H, and -M. In this study, we identified alternative splice variants of exon 6a in other Mitf isoforms (Mitf-E, -J, and -mc) in melanocytes, mast cells, macrophages, and heart. We also compared the transcriptional activity of Mitf variants containing exon 6a to that of Mitf variants that did not contain exon 6a. PCR-RFLP analysis revealed that expression of Mitf with exon 6a was comparable with that of Mitf without exon 6a, irrespective of the specificity of the first exon, or cell type, although Mitf isoforms with different first exons were expressed in a cell type-dependent manner. Luciferase-based reporter assays revealed that transcription of Tyrosinase, which is known Mitf-regulated gene, was elicited more efficiently by expression of Mitf isoforms containing exon 6a, compared to isoforms that did not contain exon 6a. However, when transcription of Tyrp-1, Mmcp-6, and PAI-1 was examined, no significant differences were detected between Mitf isoforms with exon 6a and those without exon 6a, except for Tyrp-1 transcription by Mitf-D/E isoform. These results reveal a diverse pattern of gene expression and different transcriptional activities of Mitf isoforms, suggesting discrete regulation of gene transcription in specific tissues by Mitf.

[15 cases of pulmonary Mycobacterium scrofulaceum infection].

OBJECTIVES: We described clinical features of pulmonary Mycobacterium scofulaceum disease. MATERIALS AND METHODS: We described 15 cases of pulmonary Mycobacterium scrofulaceum infection admitted to National Hospital Organization Omuta National Hospital from 1989 to 2003 and reviewed the clinical feature, the findings of chest radiograph, and clinical course. RESULTS: Sex ratio was 8 male cases and 7 female cases, and the average age was 65.9 years old. Smoking history was found in 8 patients and occupational history of the dust inhalation was found in 7 patients with pulmonary M. scrofulaceum infection. There were 11 cases of tuberculosis-like form and 4 cases of nodular-bronchiectasis form according to the NTM Research society classification based on the findings of chest radiography. Improvement of the findings of chest radiography was seen in 4 patients by therapy, while no change or aggravation in 11 patients. Five patients died and among them, 3 died due to aggravation of pulmonary M. scrofulaceum infection. DISCUSSION: Cases showing tuberculosis-like form were dominant, and most of them showed extensive lesions when they were diagnosed, and these facts were considered to be major factors of difficulty in the treatment of this infection. The facts that 7 cases had occupational exposure to the dust, obstructive pulmonary disease in 3 cases, and 6 cases showed sputum culture positive for other nontuberculous mycobacteriosis, suggest that local resistance of lung might be attenuated, and this could be one of factors of onset and development of this infection. Only 4 cases showed improvement, while 5 cases died (primary disease death in 3 cases) and it was thought that the prognosis of the disease was in general poor.

Synthetic studies of tedanolide, a marine macrolide displaying potent antitumor activity. Stereoselective synthesis of the C13-C23 segment.

[structure: see text] A highly stereoselective synthesis of the C13-C23 segment of tedanolide (1), an 18-membered macrolide isolated from the Caribbean sponge Tedania ignis, displaying significant cytotoxicity against KB and PS tumor cell lines, is described which involves two stereoselective epoxidations of regioisomeric trisubstituted double bonds and a stereospecific S(N)2' methylation reaction of a trans-gamma,delta-epoxy-cis-alpha,beta-unsaturated ester as the key steps.

[A case of cervical and mediastinal lymph nodes tuberculosis, tuberculous pleurisy, spinal caries and cold abscess in the anterior chest wall].

A 61-year-old woman with schizophrenia that had been treated in a psychiatric hospital was admitted to our hospital because of subileus and back pain. Though subileus was improved, she had a sudden attack of fever 7 days later and developed right pleural effusion, a cold abscess in the anterior chest wall and swelling of a thumb-sized right cervical lymph node which broke through the skin. We made a diagnosis of cervical and mediastinal lymph nodes tuberculosis, tuberculous pleurisy, spinal caries and cold abscess in the anterior chest wall due to the biopsy findings of the specimen taken from the cervical lymph node, examination of pleural effusion, chest CT, bacteriological examination of the cold abscess and spinal MRI. We started chemotherapy with the antituberculous drugs (HRSZ) and symptoms except back pain improved. She complained of paresis of the both lower extremities, which completely paralyzed 8 months later in spite of continued chemotherapy. Thereafter her paralysis was gradually improved and she was able to walk by herself after 12 months chemotherapy.