Comparative study on the cytotoxic effects of benzalkonium chloride on the Wong-Kilbourne derivative of Chang conjunctival and IOBA-NHC cell lines.

PURPOSE: The Wong-Kilbourne derivative of Chang conjunctiva-derived cell line has been widely used for toxicological and functional in vitro studies on the ocular surface. The common reserve to this cell line is the reported contamination with HeLa cells. Thus, the IOBA-NHC spontaneously immortalized conjunctival epithelial cell line has been recently developed and did not show other cell type contamination. Our purpose was to determine whether both cell lines would be equally suitable for in vitro toxicological studies. Therefore, we compared in these two cell types the toxic effects of the preservative, benzalkonium chloride (BAC); its toxicity has been often reported on conjunctival in vivo and in vitro models. METHODS: The necrotic, apoptotic, and oxidative effects of BAC were evaluated on Chang and IOBA-NHC cell lines using microplate cytofluorometry tests (neutral red, 2,7- dichlorofluorescein diacetate dye [H(2)DCF-DA], hydroethidine, and Yopro-1), flow cytometry (Annexin V/7-AAD and DNA content tests), and standard immunofluorescence stainings. Cells were exposed to five concentrations of BAC (10(-2)%, 5.10(-3)%, 10(-3)%, 10(-4)%, and 10(-5)%) for two incubation times: 15 min of treatment and 15 min of treatment followed by 24 h of cell recovery in complete medium. RESULTS: All parameters of toxicity increased in a BAC dose-dependent manner on both cell lines. CONCLUSIONS: The comparison of BAC toxicity on both cell lines supported the use of IOBA-NHC and Chang cells for toxicological in vitro studies. Drawbacks of both cell lines have to be known and considered in studies performed on these cell lines.

Reduction of quaternary ammonium-induced ocular surface toxicity by emulsions: an in vivo study in rabbits.

PURPOSE: To evaluate and compare the toxicological profiles of two quaternary ammonium compounds (QAC), benzalkonium chloride (BAK), and cetalkonium chloride (CKC), in standard solution or cationic emulsion formulations in rabbit eyes using newly developed in vivo and ex vivo experimental approaches. METHODS: Seventy eyes of 35 adult male New Zealand albino rabbits were used in this study. They were randomly divided into five groups: 50 microl of phosphate-buffered saline (PBS), PBS containing 0.02% BAK or 0.002% CKC (BAK Sol and CKC Sol, respectively), and emulsion containing 0.02% BAK or 0.002% CKC (BAK Em and CKC Em, respectively) were applied to rabbit eyes 15 times at 5-min intervals. The ocular surface changes induced by these eye drops were investigated using slit-lamp examination, flow cytometry (FCM), impression cytology (IC) on conjunctiva, and corneal in vivo confocal microscopy (IVCM). Standard immunohistology in cryosections was also examined for cluster of differentiation (CD) 45+ infiltrating and terminal deoxynucleotidyl transferase-mediated dUTP-nick end labeling (TUNEL)+ apoptotic cells. RESULTS: Clinical observations and IVCM showed that the highest toxicity was induced by BAK Sol, characterized by damaged corneal epithelium and a high level of inflammatory infiltration. BAK Em and CKC Sol presented moderate effects, and CKC Em showed the lowest toxicity with results similar to those of PBS. Conjunctival imprints analyzed by FCM showed a higher expression of RLA-DR and TNFR1 markers in BAK Sol-instilled eyes than in all other groups, especially at 4 h. Immunohistology was correlated with in vivo and ex vivo findings and confirmed this toxicity profile. A high level of infiltration of CD45+ inflammatory cells and TUNEL+ apoptotic cells was observed in limbus and conjunctiva, especially in QAC solution-receiving eyes compared to QAC emulsion-instilled eyes. CONCLUSIONS: The acute administration of 15 instillations at 5 min intervals was a rapid and efficient model to assess quaternary ammonium toxicity profiles. This model showed the highest toxicity, induced by the BAK solution, and the lowest level of toxicity, induced by the CKC emulsion. These in vivo and ex vivo experimental approaches demonstrated that ocular surface toxicity was reduced by using an emulsion instead of a traditional solution and that a CKC emulsion was safe for future ocular administration.

Cytoprotective effect against UV-induced DNA damage and oxidative stress: role of new biological UV filter.

The majority of chemical solar filters are cytotoxic, particularly on sensitive ocular cells (corneal and conjunctival cells). Consequently, a non-cytotoxic UV filter would be interesting in dermatology, but more especially in ophthalmology. In fact, light damage to the eye can be avoided thanks to a very efficient ocular antioxidant system; indeed, the chromophores absorb light and dissipate its energy. After middle age, a decrease in the production of antioxidants and antioxidative enzymes appears with accumulation of endogenous molecules that are phototoxic. UV radiations can induce reactive oxygen species formation, leading to various ocular diseases. Because most UV filters are cytotoxic for the eye, we investigated the anti-UV properties of Calophyllum inophyllum oil in order to propose it as a potential vehicle, free of toxicity, with a natural UV filter action in ophthalmic formulation. Calophyllum inophyllum oil, even at low concentration (1/10,000, v/v), exhibited significant UV absorption properties (maximum at 300nm) and was associated with an important sun protection factor (18-22). Oil concentrations up to 1% were not cytotoxic on human conjunctival epithelial cells, and Calophyllum inophyllum oil appeared to act as a cytoprotective agent against oxidative stress and DNA damage (85% of the DNA damage induced by UV radiations were inhibited with 1% Calophyllum oil) and did not induce in vivo ocular irritation (Draize test on New Zealand rabbits). Calophyllum inophyllum oil thus exhibited antioxidant and cytoprotective properties, and therefore might serve, for the first time, as a natural UV filter in ophthalmic preparations.

Modulated expression of cell surface molecules and in vivo outgrowth of modified melanoma cells.

Modulation of cell surface molecules involved in immune recognition and cellular interactions (class I major histocompatibility complex or MHC-I, B7.1 or CD80, integrin alpha4 or CD49d, tetraspanins CD9, CD81) was examined in modified B16 melanoma cells displaying either inhibited IGF-I expression or transfected OVA encoding gene. It was shown that inhibiting IGF-I expression or inserting OVA encoding gene did not lead to modification relevant to the presence of MHC-I or B7.1. However downregulation of tetraspanin CD9 was observed in modified IGF-I but not in OVA encoding gene inserted melanoma cells. Expression of tetraspanin CD81 and integrin alpha4/CD49d remained unchanged. Inoculated into syngeneic recipients, the modified melanoma cells exhibited significant delayed outgrowth with a reduction in the percentage of lethal tumors observed essentially in hosts injected with inhibited IGF-I expression cells.

Risk factors for NIDDM in white population. Paris prospective study.

Risk factors for non-insulin-dependent diabetes mellitus (NIDDM) were assessed in a population of 5042 middle-aged white men, initially nondiabetic, who were followed 3 yr. The subjects were participants in the Paris Prospective Study I. Sixty-three subjects developed diabetes during the follow-up. Plasma glucose concentration in the years before the occurrence of the disease was a major risk factor. Subjects with normal glucose tolerance but elevated fasting plasma glucose exhibited a similar risk of developing NIDDM as did subjects classified as having impaired glucose tolerance on the basis of 2-h postload glucose. In a multiple logistic regression, a high fasting plasma insulin concentration and a low 2-h plasma insulin concentration after a glucose load in association with a high body mass index were independent predictors of conversion to NIDDM from impaired glucose tolerance. Previously, this result had been found only in Nauruans, Pima Indians, and Japanese. This demonstrates for the first time in a white population that a high fasting and low 2-h insulin concentration is predictive of conversion to NIDDM from impaired glucose tolerance.

[Postoperative endophthalmitis: 2000-2002 results in the XV-XX National Ophthalmologic Hospital]. / Infections nosocomiales endoculaires au CHNO des XV-XX de 2000 à 2002.

PURPOSE: Prevention of nosocomial infection is a priority for the Infection Control Committee (ICC). Following their recommendations, the XV-XX National Ophthalmologic Hospital's ICC conducted a survey on cases of infection and we report these results for the 2000-2002 period. METHODS: During the 2000-2002 period, 21,384 programmed intraocular surgeries were done. Every day, a hygiene coordinator was informed of each bacterial or fungal laboratory test on intraocular samples and for all patients who were hospitalized for endophthalmitis. After data analysis with a referent ICC physician, resulting infection was declared postoperative nosocomial endophthalmitis. For these patients, prophylactic antibiotic use, the surgery report, and bacterial laboratory test results were reviewed. RESULTS: The overall 3-year incidence of suspected postoperative endophthalmitis after intraocular surgery was 2.0 per 1000 (42 cases). Confirmed microbiological growth was demonstrated in 19 cases (45%). For cataract surgery, the incidence was 1.0 per 1000 for acute-onset culture-proven postoperative endophthalmitis, 0.1 per 1000 for delayed culture-proven postoperative endophthalmitis, 2.1 per 1000 for acute-onset suspected postoperative endophthalmitis and 0.5 per 1000 for delayed suspected postoperative endophthalmitis. Gram-positive cocci were isolated in 77%. Twenty-one patients received systemic prophylactic antibiotics. Bacterial growth was positive in five of these 21 cases. For two cases, organisms were resistant to the prophylactic antibiotics used. CONCLUSION: Monitoring postoperative nosocomial infection is mandatory to detect incidence variation and evaluate infection control management. Prophylactic antibiotic efficacy remains to be evaluated.

High density lipoprotein cholesterol and alcohol consumption in a French male population.

The mean high density lipoprotein cholesterol (HDL-C) level in a sample of 640 apparently healthy male employees of a branch of the Paris civil service, aged 22-56, appears high (between 56.5 and 61.8 mg/dl depending on age groups). A positive relationship between HDL-C and alcohol intake is observed only after age 30, but is revealed in all age groups when the triglyceride level is taken into account. Differences in drinking habits by age may explain this. The moderate effect of alcohol intake on HDL-C is not sufficient to account for the high mean levels observed.

Mitochondrial activity and glutathione injury in apoptosis induced by unpreserved and preserved beta-blockers on Chang conjunctival cells.

PURPOSE: Quaternary ammonium ions have been demonstrated to induce apoptosis correlated with superoxide anion production in vitro. The purpose of this study was to further investigate the mechanisms of benzalkonium chloride (BAC), unpreserved and preserved beta-blocker eye-drops-induced programmed cell death, with special attention to the roles of mitochondrial transmembrane potential and intracellular reduced glutathione. METHODS: Chang conjunctival cells were incubated with different concentrations of unpreserved or preserved timolol (0.1%, 0.25%, and 0.4%), or carteolol (1% and 2%), or BAC (0.0001% to 0.01%) for 15 minutes, or for 15 minutes with a 24-hour recovery period in normal medium. Cellular viability (neutral red test), mitochondrial activity (rhodamine 123 test), intracellular reduced glutathione (monochlorobimane test), DNA condensation (Hoechst 33342 test), and reactive oxygen species (ROS) production (dichlorofluorescein diacetate and hydroethidine tests) were evaluated using microplate cold-light cytofluorometry. RESULTS: A significant, concentration-dependent decrease in cellular viability was found with preserved beta-blockers and with BAC alone, whereas unpreserved preparations did not show any toxicity. Only preserved beta-blockers induced chromatin condensation associated with an alteration of mitochondrial activity and a decrease of glutathione, suggesting an apoptotic phenomenon. BAC increased glutathione after 15 minutes, whereas a decrease was observed after a recovery period. ROS production was found with preserved formulations at significantly higher levels than those observed with unpreserved drugs. CONCLUSIONS: This in vitro study demonstrates that oxidative stress, evidenced by enhanced ROS production and mitochondrial injury rather than by cellular glutathione depletion, is a mechanism involved in apoptosis induced by preservative-containing eye-drops.

Quaternary ammoniums and other preservatives' contribution in oxidative stress and apoptosis on Chang conjunctival cells.

PURPOSE: To investigate some of the toxicity mechanisms of 10 preservatives currently used in ophthalmic solutions in vitro. METHODS: A continuous human conjunctival cell line was treated with different concentrations of various preservatives for 15 minutes and for 15 minutes followed by 24 hours of cell recovery: three benzalkonium chlorides (BACs) with different hydrocarbon chain length, benzododecinium bromide (BOB), cetrimide (Cet), phenylmercuric nitrate (PM), thimerosal (thi), methyl parahydroxybenzoate (MPHB), chlorobutanol (clb), and EDTA. An inhibition study was then conducted using a 1-hour vitamin E pretreatment followed by a 15-minute BAC treatment. Membrane integrity was assessed using a neutral red test and chromatin condensation with a Hoechst 33342 test. Reactive oxygen species were measured using dichlorofluorescein diacetate test for H2O2 production and hydroethidine test for O2.- production. These tests were performed using microplate cold light cytofluorometry. Cell size and DNA content were also analyzed using flow cytometry. Confocal microscopy was used to explore morphologic changes. RESULTS: A significant decrease of membrane integrity with chromatin condensation was observed with all the quaternary ammoniums tested at concentrations of 0.005% and higher. The effect was amplified after 24 hours of cell recovery. The other preservatives tested did not decrease membrane integrity. H2O2 production was observed with all the preservatives, whereas O2.- production was significantly higher with the quaternary ammoniums at 0.005% and 0.01%, compared with the other preservatives. Flow cytometry results confirmed the cytotoxicity observed with cold light cytofluorometry. CONCLUSIONS: The quaternary ammoniums tested (BAC, BOB, and Cet) were the most cytotoxic preservatives in the current model. An apoptotic mechanism appeared to be present at low concentrations of quaternary ammoniums, whereas a necrotic process appeared at higher concentrations. Superoxide anions may play an important role in tissue damage induced by preservatives in ocular surface disorders.

Fas- and interferon gamma-induced apoptosis in Chang conjunctival cells: further investigations.

PURPOSE: Previously interferon (IFN)gamma-induced apoptosis and expression of inflammation-related proteins in a human conjunctival cell line were demonstrated. The aim of this study was to further investigate the mechanisms of IFNgamma-, Fas-, and cycloheximide (CHX)-induced programmed cell death, with special attention to the role of transcriptional factors NF-kappaB and STAT1. METHODS: In a human conjunctival cell line (Chang conjunctival cells) apoptosis was induced with 500 ng/ml anti-Fas antibody (anti-Fas ab) alone (24 or 48 hours) or, as previously reported, with 300 U/ml of human recombinant IFNgamma alone (48 hours). To study the role of IFNgamma on Fas-induced apoptosis, cells were treated first with IFNgamma at 30 U/ml during 24 hours (nontoxic dose), and then anti-Fas ab was applied for 24 hours. Moreover, to study the influence of CHX on Fas- and IFNgamma-induced apoptosis, cells were treated for 24 hours with 300 U/ml IFNgamma together with a nontoxic concentration (1 microg/ml) of CHX, or with 500 ng/ml anti-Fas ab together with 1 microg/ml CHX (24 hours). After treatment, cell viability (neutral red assay), mitochondrial membrane potential (rhodamine 123 assay), chromatin condensation (Hoechst 33342 assay), and the index Hoechst/neutral red were studied by cold light microplate cytometry. The apoptotic process was sought for by contrast phase microscopy and DAPI staining and was confirmed by immunoblotting of PARP. Activation of caspase-3 (CPP32) and caspase-8 were investigated by Western blot analysis. NF-kappaB and STAT DNA-binding activities were studied by electrophoretic mobility shift assays (EMSA). RESULTS: After 24 and 48 hours of treatment with anti-Fas ab alone, 15% to 20% and 30%, respectively, of apoptotic cells were observed. When anti-Fas sera were applied after IFNgamma pretreatment or together with CHX, 50% to 80% of cells demonstrated morphologic characteristics of programmed cell death. Apoptosis was confirmed by a cleavage of PARP and CPP32, by caspase-8 activation, and by an index Hoechst/neutral red greater than one. All these modifications were preceded by a decrease in mitochondrial membrane potential. EMSA revealed that NF-kappaB was activated after IFNgamma and anti-Fas ab treatments and inhibited after CHX treatment. STAT1 was strongly activated after IFNgamma treatment and only in a minor degree after anti-Fas ab treatment. STAT1-binding activity persisted after CHX treatment. CONCLUSIONS: The relative resistance of Chang cells toward Fas-induced apoptosis could be related to the activation of NF-kappaB. IFNgamma-induced programmed cell death preferentially involves the activation of STAT1 that counterbalances NF-kappaB antiapoptotic effects. In fact, Fas-induced apoptosis was potentiated by IFNgamma or CHX treatments. These results suggest that NF-kappaB activation could maintain cell viability as well as participate in IFNgamma-induced inflammatory modifications, whereas STAT1 activation could provide, in this model, a proapoptotic signal.

The high risk of death by alcohol related diseases in subjects diagnosed as diabetic and impaired glucose tolerant: the Paris Prospective Study after 15 years of follow-up.

The 15 year mortality rates and causes of death are reported for the Paris Prospective Study cohort of 7180 working men, aged between 44 and 55 years who attended the first follow-up examination. All subjects were classified as normoglycaemic, impaired glucose tolerant or diabetic according to the WHO criteria, following an oral glucose tolerance test. The relative risks of death in comparison to the normoglycaemic group were 1.6 for impaired glucose tolerant and 2.3 for diabetic subjects; for death due to coronary heart disease: 1.7 and 2.3 respectively; for death due to alcohol and cirrhosis: 7.0 and 13.3 respectively. It appears that in this cohort a proportion of subjects screened as diabetic have impaired liver function and disturbed carbohydrate metabolism, due to excessive alcohol consumption. Alcohol should be investigated as a possible risk factor for diabetes, particularly in epidemiological studies where diabetes is diagnosed by the oral glucose tolerance test and the population has a high consumption of alcohol.

Varicose veins: a risk factor for atherosclerotic disease in middle-aged men?

The prevalence of varicose veins was higher among lower social subjects and was positively associated with a body-mass index, cigarette consumption and diastolic blood pressure. A detailed dietary survey in a subsample of the population showed a significantly higher total calory intake in men with varicose veins but no difference in the distribution of the various nutrients. During follow up for subsequent atherosclerotic disease (average 6.6 yrs), men with varicose veins were at a significantly higher risk for intermittent claudication and, at least in the lower social class, for hard coronary heart disease. No association was found with angina pectoris incidence.

High free fatty acid concentration: an independent risk factor for hypertension in the Paris Prospective Study.

BACKGROUND: An inconsistent relationship has been reported between insulin and hypertension incidence. Free fatty acids are related to insulin-resistance and may have a direct effect on hypertension. We examined the effect of free fatty acids on hypertension incidence, taking into account other abnormalities of the insulin-resistance syndrome. METHODS: In all, 2968 non-hypertensive and non-diabetic Caucasian men were followed for 3 years. Hypertension incidence was defined as systolic blood pressure (SBP) > or =160 mmHg or diastolic blood pressure (DBP) > or =95 mmHg or drug treatment for hypertension. RESULTS: Free fatty acid elevation was a highly significant risk factor for hypertension when controlled for age, family history of hypertension, alcohol consumption, body mass index, iliac circumference and weight change. Further controlling for SBP, heart rate and fasting insulin and glucose did not decrease its predictive power (hazard rate ratio [RR] = 1.58, 95% confidence interval [CI]: 1.30-1.91 comparing the 90th to the 10th percentiles at fasting; RR = 1.54, 95% CI: 1.33-1.79 at 2 h). In a forward stepwise model controlled for age, family history of hypertension, alcohol consumption and SBP, the selected variables explaining the occurrence of hypertension were, in order, weight change, 2-h free fatty acids, iliac circumference and fasting free fatty acids, whereas body mass index, heart rate, insulin, glucose and other lipids did not enter into the model. CONCLUSIONS: Free fatty acids elevation, when controlled for all known risk factors and other abnormalities of the insulin-resistance syndrome, is a risk factor for hypertension. These results highlight the possible benefits of treatment using free fatty acid oxidation inhibitors.

The Paris Cardiovascular Risk Factor Prevention Trial. Effects of two years of intervention in a population of young men.

The Paris Cardiovascular Risk Factor Prevention Trial was designed to determine whether individualised intervention could induce a reduction in the coronary risk factor levels in young men. Three thousand three hundred and thirty-six men aged 25 to 35, working in the 160 sections of a large Parisian administration, were examined. The section were randomly allocated to a control and an intervention group. Advice concerning diet, cigarette smoking, and physical activity was provided repeatedly to the subjects in the intervention group. Two years after the first intervention, the first 1292 subjects who entered the study, whether from the intervention or the control group, were recalled; 86% of the intervention group and 84% of the control group responded. The changes in weight, blood pressure, and cigarette smoking in the intervention group, corrected for changes in the control group, were respectively -0.4 kg (p = 0.06), -1.4 mm Hg (p less than 0.05), and -1.2 cigarettes (p less than 0.01). There was no difference between the two groups in serum cholesterol change. Most of these results concerning young men are in agreement with recently reported results of community intervention programmes in middle-aged men.

Evidence of prooxidant and antioxidant action of melatonin on human liver cell line HepG2.

The aim of this study was to evaluate melatonin cytotoxicity by measuring its effects on various cellular targets. Cell viability, intracellular reduced glutathione (GSH) level, and reactive oxygen species (ROS) production were assessed in the human liver cell line (HepG2), after incubation with increasing melatonin concentrations (0.1-10,000 microM). The incubation times tested were 24, 72, and 96 h for cell viability and intracellular GSH level, and 15 and 45 minutes for ROS production. Cellular target evaluations were possible in living cells by means of a new microplate cytofluorimeter. This technology was suitable for the assessment of cell viability, GSH level, and ROS overproduction with, respectively, neutral red, monochlorobimane (mBCl), and 2',7'-dichlorofluorescin diacetate (DCFH-DA) fluorescent probes. At the lowest melatonin concentrations (0.1-10 microM) and for a relatively short incubation time (24 h), the antioxidant effect of melatonin was revealed by an increased intracellular GSH level, associated to cell viability improvement. In contrast, after longer incubation (96 h), cell viability significantly decreased with these lowest melatonin concentrations (0.1-10 microM). Moreover, high melatonin concentrations (1,000-10,000 microM) induced GSH depletion. This oxidative stress is associated with ROS overproduction from 10 microM after only 15 minutes of incubation. This dual effect is strong evidence that, in vitro, melatonin can be both antioxidant and prooxidant on the human liver cell line, depending on the concentration and incubation time.

Effect of age and photoperiodic conditions on metabolism and oxidative stress related markers at different circadian stages in rat liver and kidney.

It has been shown that some cytochrome P450-dependent enzyme activities could present daily fluctuations, particularly CYP3A isoenzymes which are enhanced during the dark period. The aim of this study was to investigate whether age and photoperiodic conditions at different circadian stages could influence these fluctuations. Young mature (10 weeks) and old (22 months) Wistar rats were initially exposed to light-dark cycles 12:12 during 4 weeks, and secondly 18:6 for either one week or six weeks. Erythromycin N-demethylase (CYP3A-dependent), 7-ethoxycoumarin O-deethylase (CYP1A-dependent) and aniline 4-hydroxylase (CYP2E-dependent) activities were determined in liver and kidney microsomes at different hours after darkness onset (HADO). In addition, liver and kidney GSH, GSHPx, ATP, TBARS were determined. During the LD 12:12 cycle, while no significant modification was observed in CYP1A- and 2E-dependent enzyme activities as functions of HADO, erythromycin N-demethylase activity (CYP3A-dependent) showed a significant increase during the second third of the dark period in both young and old rats. After switching to a LD 18:6 cycle, this variation was still observed during second third of the dark period, to a lesser but still significant degree, with no difference between one week and six weeks exposure to the new photoperiod. It can be noted that the old rats showed a significantly lower level of erythromycin N-demethylase activity than the young rats, in parallel to a decrease in GSH, GSHPx and ATP, and an increase in TBARS. These results confirm the lower resistance of old animals to oxidative stress. The observed variations in metabolism parameters underline the need for study designs in pharmaco-toxicology taking into account the possible risks induced by circadian changes, especially in aged subjects.

Phalloidin hepatotoxicity in rats in vivo. Effect of a sympatholytic agent: propranolol.

Phalloidin, one of the main toxins of Amanita phalloides, induced hepatotoxicity in female Wistar rats at 0.9 mg/kg dose i.p. Biliary secretion was selectively inhibited after 3h, but was restored after 24 h. Phalloidin also induced a cytolytic lesion, but not a fatty liver, as in alpha-amanitin intoxication. Propranolol pretreatment (30 min prior to phalloidin injection) did not afford protection against hepatotoxicity, but increased alkaline phosphatase, 5'-nucleotidase and aminotransferase activities.

Enzyme induction with high doses of rifampicin in Wistar rats.

Hepatic microsomal enzyme activities were determined in female Wistar rats after 1 and 8 days of oral administration of high doses of rifampicin (RFP) (400 mg/kg/day). After 8 days, the level of cytochrome P-450 doubled and the activities of NADPH-cytochrome c reductase and benzphetamine N-demethylase were significantly increased. The observed changes in enzymic activities are consistent with the possibility that RFP induces a special form of cytochrome P-450, responsible for the metabolism of the antibiotic (demethylation and reduction of rifampicin quinone). Considering the role of the endoplasmic reticulum in lipid metabolism, the inducing activity of RFP might also contribute to the observed accumulation of lipids in the liver.

Tacrine-induced Reactive Oxygen Species in a Human Liver Cell Line: The Role of Anethole Dithiolethione as a Scavenger.

The mechanisms leading to tacrine (THA) hepatotoxic effects are not yet fully understood. Reactive oxygen species (ROS) overproduction and intracellular reduced glutathione (GSH) depletion are common mechanisms involved in drug toxicity. The aim of this study was to investigate, on the human liver cell line HepG2, whether THA at human blood concentrations induces ROS production stimulation and/or GSH depletion. A possible effect of a free radical scavenger, anethole dithiolethione (ADT), was also assessed. ROS production was measured with a fluorogen probe 2',7'-dichlorofluorescin diacetate (DCFH-DA). Reduced GSH and cell viability were measured with, respectively, monochlorobimane (mBCl) and neutral red probes. Assays were performed directly on living adherent cells in 96-well microplates, and sensitive fluorescent detection used microplate cytofluorimetry with cold light fluorimetry technology. The results showed that THA induced a concentration-dependent increase in ROS production and a decrease in GSH. Furthermore, for THA concentrations between 10 and 100 mum, ADT protected cells from ROS production stimulation and GSH depletion induced by THA. In conclusion, our in vitro study demonstrates that oxidative stress, evidenced by enhanced ROS production and GSH depletion, is a mechanism involved in THA cytotoxicity. Moreover, ADT is effective in preventing THA-induced injury.

Effects of a new cephalosporin, cefpirome (HR 810), on ATPase activities of rabbit renal proximal tubule suspensions: Comparison with cephaloridine and cefotaxime.

The effect of cefpirome (HR 810), a new cephalosporin, on ATPase activities of rabbit renal proximal tubules has been measured and compared with that of cephaloridine and cefotaxime. Only cephaloridine, the nephrotoxicity of which is well established in the rabbit, produced after 60 min treatment a dose-dependent decrease in Na(+)/K(+)- and Mg(2+)-ATPase activities. Cefotaxime and cefpirome, which have a low nephrotoxic potential in the rabbit, did not exert any effect on ATPase activities.