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D Lison

Publications and source records attributed to D Lison.

At least 55 records · Page 3Linked to original sources
PubMed1998

Evaluation of the in vitro direct and indirect genotoxic effects of cobalt compounds using the alkaline comet assay. Influence of interdonor and interexperimental variability.

The mechanisms of cobalt-induced pulmonary interstitial fibrosis and cancer are incompletely understood. DNA damage, either induced by genotoxic (direct or via oxygen radicals) or co-genotoxic (e.g. inhibition of DNA repair) processes may play an important role in the initiation of cancer. The alkaline comet assay provides a sensitive tool to investigate these two processes. Cobalt metal, a mixture of cobalt with tungsten carbide and cobalt chloride, were compared for their DNA-damaging capacity. Concentrations from 0 to 6.0 microg Co-equivalent/ml were tested. All three compounds were able to induce DNA damage in isolated human lymphocytes from three donors, in a dose- and time-dependent way. A relatively large interexperimental and interdonor variability in response was observed. This was ascribed to technical parameters and unidentified individual factors. This confirms the importance of repeating experiments using the same and different donors. The DNA-damaging potential of the cobalt-tungsten carbide mixture was higher than that of cobalt metal and cobalt chloride, which had comparable responses. No significant increase of DNA migration was observed when the DNA of cells treated with cobalt metal, cobalt-tungsten carbide or tungsten carbide were incubated with the oxidative lesion-specific enzyme formamidopyrimidine DNA glycosylase. This suggests that during the short treatment period no substantial oxidative damage to DNA was produced. Cobalt metal was able to inhibit the repair of methylmethanesulphonate-induced DNA damage. This was concluded from simultaneous exposure to cobalt and methyl methanesulphonate, post-incubation and post-treatment with 1.2 microg/ml cobalt of methyl methanesulphonate-treated cells.

Adult↗
PubMed1998

Upregulation of urokinase in alveolar macrophages and lung tissue in response to silica particles.

Impaired fibrinolytic activity and persistent fibrin deposits in lung tissue have been associated with lung fibrotic disorders. The present study examined the sources of plaminogen activator (PA) changes induced by a single intratracheal administration of silica particles (5 mg) in the mouse lung. We found in both control and silica-treated animals that amiloride almost totally abolished PA activity in bronchoalveolar lavage (BAL) fluid (BALF), indicating that initial upregulation (from day 1) as well as sustained PA activity (up to day 30) observed in response to silica is related to changes in urokinase-type PA (uPA). The upregulation of BALF uPA activity was associated with a marked and persistent increase in uPA mRNA levels in lung tissue. Changes in uPA expression were also reflected in the BAL cell fraction. A maximal and constant increase in cell uPA activity was associated with the early response to silica, whereas significant but lower upregulation was still noted at the fibrotic stage. From days 3 to 30, a progressive increase in uPA mRNA levels was noted in BAL inflammatory cells elicited by silica. Because the number of BAL neutrophils was strongly correlated with BALF and BAL cell-associated uPA activity, their involvement in uPA upregulation was addressed by inducing neutropenia with cyclophosphamide (200 mg/kg ip) before administration of the silica. Neutrophilic depletion did not, however, reduce, and even increased, the BAL cell-associated uPA activity. At the BALF level, neutropenia did not change PA activity in silica-treated mice, pointing to alveolar macrophages as the principal source of uPA in response to silica. Immunohistochemical stainings identified alveolar macrophages and pneumocytes as uPA-expressing cells in silica-treated animals (day 30). Intense and heterogenous staining was observed in silicotic nodules. These findings indicate that urokinase produced by alveolar macrophages is operative not only at the alveolitis stage but also later in the fibrotic process, produced by silica particles, supporting the role of uPA in fibrogenesis.

Amiloride↗
PubMed1998

Role of interleukin-10 in the lung response to silica in mice.

There is evidence that, following exposure to crystalline silica, the release of several proinflammatory cytokines contributes to the induction of unbalanced inflammatory reaction leading to lung fibrosis. We have examined the potential contribution of interleukin-10 (IL-10), an anti-inflammatory cytokine, in the development of silicosis. In a mouse model of inflammatory lung reaction induced by intratracheal instillation of silica (0.5 mg and 5 mg DQ12/mouse), the levels of IL-10 protein (determined by ELISA) both in cells obtained after bronchoalveolar lavage (BAL) and in lung tissue homogenates were significantly increased when compared with controls. After in vitro lipopolysaccharide (LPS) stimulation (1 microg/ml), BAL cells obtained from silica-treated animals produced significantly more IL-10 protein and mRNA than cells obtained from control animals. To examine the role of IL-10 in the lung reaction induced by silica, IL-10-deficient animals were instilled with 5 mg of silica. Twenty-four hours after treatment, the amplitude of the inflammatory response (lactate dehydrogenase [LDH], protein and number of inflammatory cells in BAL) was significantly greater in IL-10-deficient animals than in the wild type. In contrast, the fibrotic response, evaluated by measuring lung hydroxyproline content and by histopathologic analysis 30 days after silica, was significantly less important in IL-10-deficient than in wild-type mice. Together, these data suggest that increased IL-10 synthesis induced by silica can limit the amplitude of the inflammatory reaction, but also contributes to amplify the lung fibrotic response.

Animals↗
PubMed1998

Expression of plasminogen activator inhibitors type-1 and type-2 in the mouse lung after administration of crystalline silica.

Altered expression of plasminogen activator inhibitors (PAIs) is of potential relevance to the process of lung fibrosis. To clarify the involvement of PAIs in interstitial lung diseases, we examined whether alterations in PAI-1 and PAI-2 were induced in response to a single intratracheal administration of a fibrosing dose of crystalline silica in mice (5 mg x animal(-1)). The time course of changes in PAI activity and PAI-1 protein were characterized in bronchoalveolar lavage fluid (BALF) and changes in PAI-1 and PAI-2 messenger ribonucleic acid (mRNAs) were monitored by reverse transcriptase polymerase chain reaction (RT-PCR) in BALF cells and lung tissue up to the fibrotic stage of the disease. Substantial levels of PAI activity were found in BALF of control animals, whereas no PAI-1 protein was detected. In response to silica treatment, we observed an acute increase of PAI activity and PAI-1 protein levels in BALF (day 1), associated with an induction of PAI-1 and PAI-2 mRNA levels in lung tissue. In alveolar macrophages, silica treatment induced a persistent upregulation of PAI-2 mRNA only. One month after silica treatment, PAI activity was undetectable in BALF while substantial PAI activity was still present in controls. At the same time point, sustained upregulation of PAI-1 and PAI- 2 mRNAs was, however, noted in lung tissue of animals treated with silica. These findings support the possible implication of PAIs in the remodelling process induced by silica in the lung.

Animals↗
PubMed1997

Epidemic of liver disease caused by hydrochlorofluorocarbons used as ozone-sparing substitutes of chlorofluorocarbons.

BACKGROUND: Hydrochlorofluorocarbons (HCFCs) are used increasingly in industry as substitutes for ozone-depleting chlorofluorocarbons (CFCs). Limited studies in animals indicate potential hepatotoxicity of some of these compounds. We investigated an epidemic of liver disease in nine industrial workers who had had repeated accidental exposure to a mixture of 1,1-dichloro-2,2,2-trifluoroethane (HCFC 123) and 1-chloro-1,2,2,2-tetrafluoroethane (HCFC 124). All nine exposed workers were affected to various degrees. Both compounds are metabolised in the same way as 1-bromo-1-chloro-2,2,2-trifluoroethane (halothane) to form reactive trifluoroacetyl halide intermediates, which have been implicated in the hepatotoxicity of halothane. We aimed to test whether HCFCs 123 and 124 can result in serious liver disease. METHODS: For one severely affected worker liver biopsy and immunohistochemical stainings for the presence of trifluoroacetyl protein adducts were done. The serum of six affected workers and five controls was tested for autoantibodies that react with human liver cytochrome-P450 2E1 (P450 2E1) and P58 protein disulphide isomerase isoform (P58). FINDINGS: The liver biopsy sample showed hepatocellular necrosis which was prominent in perivenular zone three and extended focally from portal tracts to portal tracts and centrilobular areas (bridging necrosis). Trifluoroacetyl-adducted proteins were detected in surviving hepatocytes. Autoantibodies against P450 2E1 or P58, previously associated with halothane hepatitis, were detected in the serum of five affected workers. INTERPRETATION: Repeated exposure of human beings to HCFCs 123 and 124 can result in serious liver injury in a large proportion of the exposed population. Although the exact mechanism of hepatotoxicity of these agents is not known, the results suggest that trifluoroacetyl-altered liver proteins are involved. In view of the potentially widespread use of these compounds, there is an urgent need to develop safer alternatives.

Biomarkers↗
PubMed1997

Comparative evaluation of the in vitro micronucleus test and the alkaline single cell gel electrophoresis assay for the detection of DNA damaging agents: genotoxic effects of cobalt powder, tungsten carbide and cobalt-tungsten carbide.

Although it is well known that micronuclei may arise from either DNA breakage leading to acentric chromosome fragments or from chromosome/chromatid lagging in anaphase, the ratio between the amount of DNA breakage induced and the frequency of micronuclei expressed in the following interphase is unclear. With the development of the alkaline single cell gel electrophoresis assay, which measures single strand and/or double strand breaks in a cell by cell approach, it is new possible to address this question at the cellular level. We therefore compared the genotoxic potential of pure cobalt powder (Co) and a cobalt-containing alloy, cobalt-tungsten carbide (WC-Co), involved in specific lung disorders, in parallel with the alkaline single cell gel electrophoresis (SCGE) assay (comet assay) and the cytokinesis-blocked micronucleus (MN) test, both carried out in vitro on isolated human leukocytes. The comet assay indicated that the WC-Co mixture produced a higher level of DNA damage than Co alone; WC alone was not able to induce a dose-dependent DNA breakage effect as was seen for Co and WC-Co. Results from the MN test confirmed these observations. It was clear that the clastogenic property of Co-containing dust is significantly enhanced when the Co metal is mixed with WC and suggested that their physicochemical characteristics may act as one of the important parameters responsible for the increased incidence of lung cancers observed in the population of hard metal workers. In agreement with data obtained in the same laboratory on liposoluble chemicals (PCBs and chlorinated aliphatic hydrocarbons) and from the literature, the results indicate that both the comet assay and the micronucleus test were able to detect differences in the genotoxic potential of the compounds studied. Although the micronucleus test seemed to be less sensitive to assess a synergistic DNA damaging potential of the mixture involved, it detects chromosomal aberrations (chromosome/genome mutations) and not just repairable DNA breakage or alkali-labile sites. Combination of the comet assay and the in vitro MN test might therefore be recommended for genotoxins to understand the mechanisms underlying mutagenicity and to assess the lowest efficient dose.

Adult↗
PubMed1997

Reduction of the ex vivo production of tumor necrosis factor alpha by alveolar phagocytes after administration of coal fly ash and copper smelter dust.

We investigated the effect of intratracheally instilled coal fly ash (FA) and copper smelter dust (CU) on the lung integrity and on the ex vivo release of tumor necrosis factor alpha (TNF-alpha) by alveolar phagocytes. Groups of female NMRI mice received a single intratracheal administration of different particles normalized for the arsenic content (20 micrograms/kg body weight, i.e., 600 ng arsenic/mouse) and the particle load (100 mg/kg body weight, i.e., 3 mg/mouse). Mice received tungsten carbide (WC) alone (100 mg/kg), FA alone (100 mg/kg, i.e., 20 micrograms arsenic/kg), CU mixed with WC (CU, 13.6 mg/kg, i.e., 20 micrograms arsenic/kg; WC, 86.4 mg/kg) and Ca3(AsO4)2 mixed with WC (20 micrograms arsenic/kg; WC, 100 mg/kg). Animals were sacrificed at 1, 6, or 30 d posttreatment and analyzed by bronchoalveolar lavage for total protein (TP) content, inflammatory cell number and type, and TNF-alpha production. Additional mice were studied to evaluate particle retention by measuring total arsenic retention in the lung at appropriate times. Instillation of WC induced a mild and transient (d 1) inflammatory reaction characterized by an increase of TP and an influx of polymorphonuclear leukocytes in the alveolar compartment. Compared to WC, Ca3(AsO4)2 produced a significant increase of TP content in BALF. CU particles caused a severe but transient inflammatory reaction, while a persisting alveolitis (30 d) was observed after treatment with FA. Compared to control saline, a marked inhibition of TNF-alpha release was observed in response to LPS in all groups at d 1. Cytokine production was upregulated in WC- and Ca3(AsO4)1-treated animals after 6 and 30 d, respectively. However, a 90% inhibition of TNF-alpha production was still observed at d 30 after administration of CU and FA. Although arsenic was cleared from the lung tissue 6 d after Ca3(AsO4)2 administration, a significant fraction persisted (10-15% of the arsenic administered) in the lung of CU- and FA-treated mice at d 30. We hypothetize that suppression of TNF-alpha production is dependent upon the slow elimination of the particles and their metal content from the lung.

Animals↗
PubMed1997

Reversibility of microproteinuria in cadmium workers with incipient tubular dysfunction after reduction of exposure.

The study aimed at assessing the evolution of cadmium (Cd)-induced renal tubular dysfunction in Cd workers according to the severity of the microproteinuria observed at the time the exposure was substantially decreased. Male workers employed in the Cd production industry for whom formerly high exposure had markedly decreased by 1984 and for whom standardized medical data were available during two observation periods (1980-1984 and 1990-1992) were eligible for the study. A total of 32 Cd workers fulfilling this profile were divided into two groups on the basis of historical records of urinary Cd concentration (Cd-U) covering the period until 1984. The workers with Cd-U values of > 10 micrograms Cd/g creatinine were subdivided further on the basis of the urinary concentration of beta 2-microglobulin (beta 2 MG-U) measured during the first observation period (1980-1984). In each group, the tubular microproteinuria as reflected by beta 2 MG-U and the concentration of retinol-binding protein in urine as well as the internal Cd dose as reflected by the concentration of Cd in blood and urine were compared between the first and second (1990-1992) observation periods. Increased microproteinuria was often diagnosed in cases with Cd-U values of > 10 micrograms Cd/g creatinine. The evolution of tubular renal function has been found to depend on the extent of the body burden of Cd (as reflected by Cd-U) and the severity of the initial microproteinuria at the time high Cd exposure was reduced or ceased. When reduction of Cd exposure took place while beta 2 MG-U did not exceed the upper reference limit of 300 micrograms/g creatinine, the risk of developing tubular dysfunction at a later stage was likely to be low, even in cases with historical Cd-U values occasionally > 10 but always < 20 micrograms Cd/g creatinine. When the microproteinuria was mild (beta 2 MG-U > 300 and < or = 1,500 micrograms/g creatinine) at the time exposure was reduced, and the historical Cd-U values had never exceeded 20 micrograms Cd/g creatinine, there was indication of a reversible tubulotoxic effect of Cd. When severe microproteinuria (beta 2 MG-U > 1,500 micrograms/g creatinine) was diagnosed in combination with historical Cd-U values exceeding 20 micrograms Cd/g creatinine, Cd-induced tubular dysfunction was progressive in spite of reduction or cessation of Cd exposure.

Analysis of Variance↗
PubMed1997

Influence of the route of administration and the chemical form (MnCl2, MnO2) on the absorption and cerebral distribution of manganese in rats.

The absorption and cerebral distribution of manganese (Mn) have been studied with respect to the route of administration and the chemical form of the Mn compound. Different groups of adult male rats received either MnCl2, 4H2O or MnO2 once a week for 4 weeks at a dose of 24.3 mg Mn/kg body wt. (b.w.) by oral gavage (g.) or 1.22 mg Mn/kg b.w. by intraperitoneal injection (i.p.) or intratracheal instillation (i.t.). Control rats were treated with 0.9% saline. Four days after the last administration the rats were killed and the concentration of Mn measured in blood, hepatic and cerebral tissues (cortex, cerebellum, and striatum). The liver Mn concentration was not affected by the treatments whatever the chemical form or the route of administration of the Mn compound. Administration of MnCl2 by g., i.p., and i.t. routes produced equivalent steady-state blood Mn concentrations (about 1000 ng Mn/100 ml), representing increases of 68, 59, and 68% compared with controls, respectively. Mn concentrations were significantly increased in the cortex but to a lesser extent (g., 22%; i.p., 36%; i.t., 48%) and were higher in the cerebellum after i.p. and i.t. administrations than after oral gavage. Rats treated i.t. with MnCl2 showed an elective increase of the striatal Mn concentration (205%). In contrast, MnO2 given orally did not significantly increase blood and cerebral tissue Mn concentrations; the low bioavailability is most likely due to the lack of intestinal resorption. Administration of MnO2 i.p. and i.t., however, led to significant increases of Mn concentrations in blood and cerebral tissues. These increments were not significantly different from those measured after MnCl2 administration, except for striatal Mn after i.t. which was markedly less (48%) after MnO2 administration. A comparison of the blood Mn kinetics immediately after g. and i.t. treatment with MnCl2 or MnO2 indicated that the higher elevation of blood Mn concentration (> 2000 ng Mn/100 ml) after i.t. administration of MnCl2 could account for the elective uptake of Mn in the striatum observed in repeated dosing experiments. It is concluded that the modulation of Mn distribution in brain regions according to the route of administration and the chemical form of the Mn compound may be explained on the basis of different blood Mn kinetics and regional anatomic specificities of the striatal region.

Animals↗
PubMed1997

Effect of sulphur mustard on the expression of urokinase in cultured 3T3 fibroblasts.

The expression of plasminogen activator (PA), a serine proteinase involved in the degradation of extracellular matrix proteins, has been investigated in 3T3 fibroblasts after in vitro exposure to sulphur mustard (SM). Expression of the cell-associated enzyme has been assessed with a synthetic substrate assay and at the mRNA level. Twenty-four hours after 100 microM SM, cell viability (monitored by MTT assay) was not significantly affected, but protein synthesis (tritiated leucine incorporation) was reduced to < 20% of the control value. PA activity was significantly increased compared to control cells with a 20-fold increase after 24 h. This up-regulation was independent of the cell density, occurred maximally between days 1 and 4 and persisted for at least 6 days after exposure. Lower concentrations of SM (< or = 10 microM) did not significantly affect PA activity. Northern blotting experiments revealed an increased expression of urokinase (u-PA) transcripts in cells treated with 100 microM SM, with a peak at 10 h after exposure. Conditioned culture medium from cell cultures treated with 100 microM SM did not affect the expression of PA activity in naive or SM-treated cultures. Thiodiglycol (100 microM), the main metabolite of SM, did not influence the expression of PA in the same system. Different compounds were tested for modulation of the PA upregulation after SM exposure. Nicotinamide (5 mM), vitamin D3 (10(-10)M), extracellular calcium (2 mM) or EGTA (5 mM) had no effect. Ryanodine (10 microM) amplified the PA up-regulation by a factor of 2 and vanadate (500 microM) reduced it by approximately 50%. Dexamethasone (1 microM) added directly after SM treatment almost completely prevented the induction of PA at both the protein and mRNA levels. Overall these results demonstrate an up-regulation of urokinase in 3T3 fibroblasts after treatment with SM, which is possibly mediated by intracellular calcium mobilization. Further studies are needed to identify the significance of this proteolytic response in the pathogenesis of blistering and/or DNA repair mechanisms.

3T3 Cells↗
PubMed1997

Influence of particle surface area on the toxicity of insoluble manganese dioxide dusts.

The objective of this study was to examine the influence of specific surface area on the biological activity of insoluble manganese dioxide (MnO2) particles. The biological responses to various MnO2 dusts with different specific surface area (0.16, 0.5, 17 and 62 m2/g) were compared in vitro and in vivo. A mouse peritoneal macrophage model was used to evaluate the in vitro cytotoxic potential of the particles via lactate dehydrogenase (LDH) release. In vivo, the lung inflammatory response was assessed by analysis of bronchoalveolar lavage after intratracheal instillation in mice (LDH activity, protein concentration and cellular recruitment). In both systems, the results show that the amplitude of the response is dependent on the total surface area which is in contact with the biological system, indicating that surface chemistry phenomena are involved in the biological reactivity. Freshly ground particles with a specific surface area of 5 m2/g were also examined in vitro. These particles exhibited an enhanced cytotoxic activity, which was almost equivalent to that of 62 m2/g particles, indicating that undefined reactive sites produced at the particle surface by mechanical cleavage may also contribute to the toxicity of insoluble particles. We conclude that, when conducting studies to elucidate the effect of particles on the lung, it is important for insoluble particles such as manganese dioxide to consider the administered dose in terms of surface area (e.g. m2/kg) rather than in gravimetric terms (e.g. mg/kg).

Animals↗
PubMed1997

Biological monitoring of workers exposed to low levels of 2-butoxyethanol.

OBJECTIVES: (1) To assess the value of urinary butoxyacetic acid (BAA) measurement for the monitoring of workers exposed to low concentration of 2-butoxyethanol (BE); (2) to evaluate the in vivo effect of low occupational BE exposure on the erythrocyte lineage; and (3) to test the possible influence of genetic polymorphism for cytochrome P450 2E1 (CYP 2E1) on urinary BAA excretion rate. METHODS: Thirty-one male workers exposed to BE in a beverage package production plant were examined according to their external (BE) and internal (BAA) solvent exposure. The effect of this exposure on erythrocyte lineage [red blood cell numeration (RBC), hemoglobin (Hb), hematocrit (Htc), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), haptoglobin (Hp), reticulocyte numeration (Ret) and osmotic resistance (OR)], hepatic [aspartate aminotransferase (GOT), alanine aminotransferase (GPT)] and renal [plasmatic creatinine, urinary retinol binding protein (RBP)] parameters was also investigated. DNA purified from whole blood was used for CYP 2E1 genotyping. RESULTS: Average airborne concentration of BE was 2.91 mg/m3 (0.59 ppm) with a standard deviation of 1.30 mg/m3 (0.27 ppm). There was a relatively good correlation between external and internal exposure estimated by measuring BAA in post-shift urine samples (average 10.4 mg/g creatinine; r = 0.55; P = 0.0012). Compared with a matched control group (n = 21) exposed workers had a statistically significant decrease (3.3%; P = 0.03) in Hct while MCHC was increased (2.1%; P = 0.02). No significant difference was observed either in other erythroid parameters or in hepatic and renal biomarkers. One exposed individual exhibited a mutant allele with increased cytochrome P450 oxidative activity which coincided with a very low urinary BAA excretion. CONCLUSIONS: Single determination of BAA in post-shift urine samples can be used to assess exposure to low levels of BE. A slight but significant effect on erythroid parameters suggesting membrane damage was observed in exposed workers. The influence of the genetic polymorphism for CYP 2E1 deserves further investigation for the interpretation of urinary BAA measurements.

Adult↗
PubMed1997

In vitro genotoxic effects of hard metal particles assessed by alkaline single cell gel and elution assays.

Hard metals (WC-Co) are made of a mixture of cobalt metal (Co, 5-10%) and tungsten carbide particles (WC, >80%). Excessive inhalation of WC-Co is associated with the occurrence of different lung diseases including an excess of lung cancers. The elective toxicity of hard metal is based on a physico-chemical interaction between cobalt metal and tungsten carbide particles to produce activated oxygen species. The aim of the present study was to assess the genotoxic activity of hard metal particles as compared with Co and WC alone. In human peripheral lymphocytes incubated with Co or WC-Co, a dose- and time-dependent increased production of DNA single strand breaks (ssb) was evidenced by alkaline single cell gel electrophoresis (SCGE) and modified alkaline elution (AE) assays. Addition of 1 M formate, a hydroxyl radical scavenger, had a protective effect against the production of ssb by both WC-Co or Co alone. On the basis of an equivalent cobalt-content, WC-Co produced significantly more ssb than Co. WC alone did not produce DNA ssb detectable by the AE assay, but results obtained with the SCGE assay may suggest that it either allows some uncoiling of the chromatin loops or induces the formation of slowly migrating fragments. Overall, this in vitro study is the first demonstration of the clastogenic property of cobalt metal-containing dusts. The results are consistent with the implication of an increased production of hydroxyl radicals when Co is mixed with WC particles. The SCGE results also suggest that WC may modify the structure of the chromatin, leading to an increased DNA sensitivity to clastogenic effects. Both mechanisms are not mutually exclusive and may concurrently contribute to the greater clastogenic activity of WC-Co dust. This property of WC-Co particles may account for the excess of lung cancers observed in hard metal workers.

Cobalt↗
PubMed1996

Exogenous catalase may potentiate oxidant-mediated lung injury in the female Sprague-Dawley rat.

Enhancement of lung antioxidant capacity has been proposed in the therapy of acute lung injuries involving local accumulation of reactive oxygen species (ROS). We have studied in the female Sprague-Dawley rat the effect of intratracheal administration of catalase (CAT) on the acute lung response induced by different ROS generating systems. The lung response was assessed at several time intervals (60-360 min) by monitoring in bronchoalveolar fluid (BALF) the activity of lactate dehydrogenase and the levels of total protein, albumin, and glucose. While CAT (50,000 IU/rat) significantly reduced the biochemical changes induced by hydrogen peroxide produced by a glucose/glucose oxidase system, it markedly exacerbated the lesions induced by phorbol myristate acetate (PMA). Several observations indicate that a particular chemical species formed during the catalase inactivation process is responsible for this effect. Parallel to the development of the lung damage, we noted a rapid reduction of CAT activity (80%) in the BALF of animals treated with PMA and CAT. In vitro an inhibition of CAT activity was observed in the presence of a superoxide anion generating system, and this inhibition was prevented by superoxide dismutase (SOD). A dose of 10,000 IU superoxide dismutase did not prevent the development of the lung lesions induced by PMA plus CAT. Administered alone or in association with PMA, CAT inactivated by heat or 3-aminotriazole also caused severe lung damage. In conclusion, the present study indicates that exogenous catalase may not always protect against the inflammatory reaction resulting from an oxidative stress. In the presence of superoxide anions, catalase may aggravate the lesions, and this possibility should be kept in mind when considering an antioxidant therapy.

Albumins↗
PubMed1996

Evaluation of three methods for the detection of DNA single-strand breaks in human lymphocytes: alkaline elution, nick translation, and single-cell gel electrophoresis.

The aim of this study is to assess the ability of three methods, alkaline elution (AE), nick translation (NT), and single-cell gel electrophoresis (SCGE), to detect DNA single-strand breaks (ssb) in human peripheral blood lymphocytes (HPBL) exposed in vitro to three genotoxic agents; gamma-rays, ethyl methanesulfonate (EMS) and benzo[a]pyrene diol epoxide (BPDE). The ultimate objective is to select the most feasible, sensitive, and reproducible method for the monitoring of populations exposed to genotoxic agents. AE and NT do not seem suitable assays. AE is able to detect DNA lesions induced by the three compounds, but only at relatively high doses (2 Gy, 5 mM EMS and 20 microM BPDE). With NT, DNA alterations induced by gamma-rays are not detected and ssb are only evidenced after exposure to EMS (80 mM), which already alters the viability of the lymphocytes. Nick translation is able to detect ssb induced by 10 microM BPDE. Compared to the other assays, the sensitivity of the SCGE assay is significantly higher since statistically significant changes were detected after incubation with 0.5 mM EMS and 1.25 microM BDPE. SCGE is a relatively simple method, not time-consuming and applicable to a large number of samples per working day. In conclusion, on the basis of the results of this in vitro comparison, SCGE seems a promising method for the monitoring of populations exposed to genotoxic chemicals.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗