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The tumour suppressor gene TP53 is mutated in more than 50 % of human tumours, making it one of the most important cancer genes. We have investigated the role of TP53 in cytochrome P450 (CYP)-mediated metabolic activation of three polycyclic aromatic hydrocarbons (PAHs) in a panel of isogenic colorectal HCT116 cells with differing TP53 status. Cells that were TP53(+/+), TP53(+/− ), TP53(−/−), TP53(R248W/+) or TP53(R248W/−) were treated with benzo[ a]pyrene (BaP), dibenz[ a,h]anthracene and dibenzo[ a,l]pyrene, and the formation of DNA adducts was measured by P-postlabelling analysis. Each PAH formed significantly higher DNA adduct levels in TP53(+/+) cells than in the other cell lines. There were also significantly lower levels of PAH metabolites in the culture media of these other cell lines. Bypass of the need for metabolic activation by treating cells with the corresponding reactive PAH-diol-epoxide metabolites resulted in similar adduct levels in all cell lines, which confirms that the influence of p53 is on the metabolism of the parent PAHs. Western blotting showed that CYP1A1 protein expression was induced to much greater extent in TP53(+/+) cells than in the other cell lines. CYP1A1 is inducible via the aryl hydrocarbon receptor (AHR), but we did not find that expression of AHR was dependent on p53; rather, we found that BaP-induced CYP1A1 expression was regulated through p53 binding to a p53 response element in the CYP1A1 promoter region, thereby enhancing its transcription. This study demonstrates a new pathway for CYP1A1 induction by environmental PAHs and reveals an emerging role for p53 in xenobiotic metabolism. [ABSTRACT FROM AUTHOR]

Saturation diving is performed under extreme environmental conditions. The divers are confined to a limited space for several weeks under high environmental pressure and elevated oxygen partial pressure. At present, divers are protected against chemical exposure by standard exposure limits only adjusted for the increased exposure length, i.e. from 8 to 24 hours a day and from 5 to 7 days a week. The objective of the present study was to indicate a procedure for derivation of occupational exposure limits for saturation diving, termed hyperbaric exposure limits (HEL). Using benzene as an example, a procedure is described that includes identification of the latest key documents, extensive literature search with defined exclusion criteria for the literature retrieved. Hematotoxicity and leukemia were defined as the critical effects, and exposure limits based upon concentration and cumulative exposure data and corresponding risks of leukemia were calculated. Possible interactions of high pressure, elevated pO2, and continuous exposure have been assessed, and incorporated in a final suggestion of a HEL for benzene. The procedure should be applicable for other relevant chemicals in the divers' breathing atmosphere. It is emphasized that the lack of interactions from pressure and oxygen indicated for benzene may be completely different for other chemicals. [ABSTRACT FROM AUTHOR]

Objective. Fomepizole is the antidote of choice in toxic alcohol poisonings. Potential side effects from frequent use of fomepizole were studied in a patient admitted 154 times with ethylene glycol (EG) poisoning. The intra-individual correlation between the serum-ethylene glycol (serum-EG) and the osmolal gap (OG) EG-kinetics, and other laboratory parameters were also studied. Methods. Combined pro- and retrospective collection of material from three different hospitals, and results from autopsy. Results. A 26-year-old female with a dissociative disorder was admitted with EG poisoning a total of 154 times. Her admission data revealed a median pH of 7.31 (range 6.87--7.49), pCO2: 4.2 kPa (1.2--6.7) (32 mmHg [9--50]), HCO--3: 15 mmol/L (4--26) (15 mEq/L [4--26]), base deficit (BD): 10 mmol/L (−− 4 to 27) (10 mEq/L [--4 to 27]), serum-creatinine 65 μμmol/L (40--133) (0.74 mg/dL [0.45--1.51]), OG 81 mOsm/kgH2O (25--132), and serum-EG 44 mmol/L (4--112) (250 mg/dL [25--700]). She was treated with fomepizole 99 times, ethanol 60 times (with a combination of both six times), and dialysis 73 times. The correlation between serum-EG and OG was good (r2 == 0.76). She was finally found dead outside hospital with an EG blood concentration of 81 mmol/L (506 mg/dL). An autopsy revealed calcium oxalate crystals in the kidneys, slight liver steatosis, and slight edema of the lungs. Discussion. The frequent use of fomepizole in this young patient was not associated with any detectable side effects; neither on clinical examination and lab screening, nor on the later autopsy. Regarding the sequelae from the repetitive EG-poisoning episodes, her kidney function seemed to normalize after each overdose. She was treated with buffer and antidote without hemodialysis 81 times without complications, supporting the safety of this approach in selected cases. [ABSTRACT FROM AUTHOR]

We have examined DNA restriction fragment length polymorphisms (RFLP) of the Ha- ras-1 gene in DNA from 118 lung cancer patients and 123 unaffected controls. When DNA samples were digested with MspI/ HpaII restriction endonucleases. Southern blot analysis demonstrated 4 common, 4 intermediate and 7 different rare alleles in the combined population after hybridization to the pGDa1 probe. Six of the rare alleles were unique for the lung cancer group and 1 rare allele for the control group. The frequency of rare alleles in lung cancer patients (10/236) was significantly different ( P<0.01) from the control group (1/246). The lung cancer group also had a significantly lower frequency of the common 2.57 kb fragment than the controls ( P<0.02). The results thus indicate that Ha- ras genotyping may be of value in lung cancer risk assessment. [ABSTRACT FROM AUTHOR]