Perspective of dental medicine students learning in remote biochemistry laboratories during COVID-19.

Students at the Monastir Faculty of Dental Medicine were required to remain inside during the COVID-19 pandemic for their own safety and in accordance with official directives. It is evident that learners' perceptions are a recognized indicator of the efficiency of any teaching approach. Therefore, we focused on students' input on the validity of online biochemistry laboratories to assure their preferences with the finest teaching approaches. The study included 116 undergraduate dental students from the Faculty of Dental Medicine of Monastir. The survey has 40 questions. This investigation covered (i) information technology tool accessibility, (ii) course presentation, interactions in a virtual classroom, teachers' availability, and (iii) preferred learning styles. The percentages were then determined for each item and assessed. Our results showed that almost students were equipped with computers, smartphones and tablets but have encountered some connectivity issues. Moreover, participants find courses well presented, approved class interactions, and were satisfied with teachers' availability. Nevertheless, students were not already prepared for entirely online learning. Despite, the overall positive perception among students toward remote education during the COVID-19 outbreak; they preferred considering shared learning between face-to-face and online once the pandemic is over.

Can we achieve ESC 2019 guidelines LDL-cholesterol target in Tunisia?

INTRODUCTION: Dyslipidemias are a major cardiovascular risk factor. The control of LDLc level is one of the major targets in patients admitted for an acute coronary syndrome (ACS). AIM: To study the lipid profile after ACS and to assess the degree of applicability of the European guidelines in Tunisia. METHODS: This was a prospective, multicentric, non-randomized study involving consecutive patients admitted for ACS between October 2019 and March 2020; for whom a lipid assessment was carried out on admission and checked after four to six weeks under high dose of statin. RESULTS: One hundred patients were included. The mean age of our population was 58.7 years and the sex ratio was 5.7. Obesity was present in 15%, Diabetes in 35%, hypertension in 34% and smoking in 61% of cases. Our patients presented with ST segment elevation myocardial infraction in 51%. The mean total plasma LDLc level was 1.04±0.26g/L. A reduction in LDLc levels of more than 50% was noted in 33% of patients. A value less than 0.55g/L of LDLc was noted in 46% of patients. The therapeutic target (LDLc.

Current and new imaging techniques in risk stratification of asymptomatic severe aortic stenosis.

Aortic stenosis (AS) is one of the most common valvular diseases in clinical practice. The prevalence of calcified AS with moderate or severe stenosis exceeds 2% after 75 years. The optimal timing of intervention for asymptomatic severe AS is uncertain and controversial. Identification of high-risk patients is based on echocardiographic parameters (left ventricular dysfunction, AS severity and progression), hemodynamic response to exercise, pulmonary hypertension, and elevated brain natriuretic peptides. However, early surgical aortic valve replacement (AVR), when compared to the watchful waiting approach, was associated with survival advantage. Moreover, new insights into pathophysiology of AS and advances in imaging modalities were helpful in the management of asymptomatic AS. In this report, we detail the potential role of echocardiography to guide timing of surgery and we discussed the use of early risk features based on recent imaging modalities.

Risk stratification for sudden cardiac death in patients with heart failure : Emerging role of imaging parameters.

BACKGROUND: Heart failure with reduced ejection fraction is a common condition that has a poor prognosis. Accurate selection of patients with ischemic heart disease and idiopathic dilated cardiomyopathy, who are at risk of sudden cardiac death (SCD), remains a challenge. In these cases, current indications for implantable cardioverter-defibrillators (ICD) rely almost entirely on left ventricular ejection fraction. However, this parameter is insufficient. Recently, noninvasive imaging has provided insight into the mechanism underlying SCD using myocardial deformation on echocardiography and magnetic resonance imaging. The aim of this review article was to underline the emerging role of these novel parameters in identifying high-risk patients. METHODS: A literature search was carried out for reports published with the following terms: "sudden cardiac death," "heart failure," "noninvasive imaging," "echocardiography," "deformation," "magnetic resonance imaging," and "ventricular arrhythmia." The search was restricted to reports published in English. RESULTS: The findings of this analysis suggest that cardiac magnetic resonance imaging and strain assessment by echocardiography, particularly longitudinal strain, can be promising techniques for cardiovascular risk stratification in patients with heart failure. CONCLUSION: In future, risk stratification of arrhythmia and patient selection for ICD placement may rely on a multiparametric approach using combinations of imaging modalities in addition to left ventricular ejection fraction.

ImpaCt of aspirin regimen on THrombin generation in diabEtic patients with acute coronary syndrome: CARTHaGE-ACS trial.

BACKGROUND: Diabetes is associated with a high rate of events after acute coronary syndrome. It was recently reported that once-daily aspirin might not provide stable biological efficacy in patients with diabetes. AIMS: We sought to compare the biological efficacy of aspirin given once a day versus aspirin divided twice per day in a population of diabetic patients with non-ST elevation acute coronary syndrome (NSTE-ACS) as assessed by the thrombin generation test. METHODS: We performed an open-label single-blind randomized study including 59 consecutive diabetic patients admitted for NSTE-ACS. Patients were randomly treated with aspirin 100 mg once a day (GA100; n = 20), aspirin 160 mg once a day (GA160; n = 19) or aspirin 100 mg twice a day (G2A100; n = 20). The primary endpoint was endogenous thrombin potential (ETP) at discharge and after 6 months. RESULTS: The mean age of our patients was 61.5 ± 9 years, and 73% were male. The baseline characteristics were comparable between the three groups. In the GA100 group, there was no significant effect on ETP variation at 6 months (1150.46 ± 504.84 vs. 1087.63 ± 454.18; p = 0.794). An increase in aspirin dose with a second daily administration of 100 mg was associated with a significant reduction in ETP at 6 months (1004.87 ± 196.2 vs. 1233.63 ± 333.5; p = 0.003). A nonsignificant decrease in ETP was seen in the GA160 group (from 1173.8 ± 388.07 to 1053.64 ± 269.93 at 6 months, p = 0.117). CONCLUSION: Only the twice-daily aspirin regimen led to better control of hypercoagulability in NSTE-ACS diabetic patients. However, no thrombin generation normalization was reported.

A giant calcified aneurysm of the basal inferior wall: a rare phenomenon.

Left ventricular aneurysms (LVA) are mainly a late consequence of transmural myocardial infarction. Approximately 80% of LVA are located in the anterior and/or apical walls, most commonly associated with left anterior descending artery occlusion but any region may be engaged. Basal inferior wall aneurysms are rare and constitute nearly 3% of all LVA. A calcified LVA is seldom observed in modern clinical practice. And a calcified basal inferior LVA is an even rarer coincidence. We report a case of an 82-year-old women with life threatening arrhythmia revealing a giant calcified aneurysm of the basal inferior wall, medically treated with good outcomes. The exact incidence of left ventricular aneurysms (LVA) following myocardial infarctions is hard to precise but it is clearly decreasing. Eighty percent (80%) of LVA are located in the anterior or apical walls, but any region may be engaged. Basal inferior wall aneurysms constitute 3% of all LVA. Echocardiography is the first diagnostic tool and there is still no clear guidelines on how to treat LVAs. Surgery is preferred but medical treatment may help improve the quality of life.

Coronary PCI revascularization novel treatment of bundle branch reentrant ventricular tachycardia.

Bundle branch reentrant ventricular tachycardia (VT) is a form of macroreentrant tachycardia. Although infrequent in occurrence, this arrhythmia presents with serious clinical manifestations and has potential for cure by catheter ablation. We report a case of bundle branch reentrant VT with ischemic source. Revascularization of culprit coronary artery was another means to treat VT. .

Protective effects of kefir against deltamethrin-induced hepatotoxicity in rats.

Deltamethrine (DLM) is a synthetic pyrethroid with broad spectrum activities against acaricides and insects. Widely used for agricultural and veterinary purposes, its human and animal exposure occurs by ingestion of contaminated water and food and leads to serious health problems. Kefir is fermented milk with numerous health favors counting restorative properties of bacterial flora, immune system stimulation, cholesterol reduction, as well as anti-mutagenic and anti-tumor properties. The present study was undertaken to examine the hepatoprotective and antioxidant potential of kefir against DLM toxicity in male Wistar albino rats. DLM-treated animals revealed a significant increase in serum biochemical parameters as well as hepatic protein and lipid oxidations but caused an inhibition in antioxidant enzymes. Additionally, we have observed an increase in hepatocyte DNA damages. This toxic effect was confirmed by histological study. Kefir administration normalized the elevated serum levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), total bilirubin (T bilirubin), and cholesterol. It also reduced DLM-induced protein carbonyl (PC) and malondialdehyde (MDA) formations. Furthermore, Kefir treatment restored catalase (CAT) and superoxide dismutase (SOD) activities. The co-treatment as well as the pre-treatment by kefir showed an improvement of oxidative status as well as suppressed inflammation and DNA damages. However, the pre-treatment seems to be the most efficient. Therefore, it could be concluded that kefir is a natural product able to protect against the hepatotoxic effects of DLM by its free radical-scavenging and potent antioxidant activity.

Protective effects of kefir against zearalenone toxicity mediated by oxidative stress in cultured HCT-116 cells.

Kefir is a fermented milk with numerous health favors counting restorative properties of bacterial flora, reduction of the symptoms of lactose intolerance, immune system stimulation, cholesterol reduction, as well as anti-mutagenic and anti-tumor properties. Zearalenone (ZEN) is a mycotoxin produced by some Fusarium species. ZEN often occurs as a contaminant in cereal grains and animal feeds. Human exposure occurs by ingestion of mycotoxin-contaminated products and can cause serious health problems. This study aimed to assess the preventive effect of kefir against ZEN toxicity in cultured HCT-116 colorectal carcinoma cells; by the evaluation of cell viability, oxidative stress status and the initiation of apoptotic cell death pathway. Our results demonstrated that ZEN inhibits cell proliferation which was accompanied by an increase in the generation of free radicals as measured by fluorescent 2,7-dichlorofluorescein (DCF) and Malondialdehyde (MDA). As an adaptive response to this redox status, we showed an induction of heat shock protein expression (Hsp 70) and an activation of antioxidant enzymes; catalase and Superoxide Dismutase (SOD). Moreover, a loss of mitochondrial membrane potential (Δѱm) was observed. The co-treatment as well as the pre-treatment by kefir showed a reduction of ZEN induced damages for all tested markers. However, the pre-treatment seems to be the most efficient, it prevented almost all ZEN hazards. Consequently, oxidative damage appears to be a key determinant of ZEN induced toxicity in cultured HCT-116 cells. In conclusion, we showed that kefir may better exert its virtue on preventive mode rather than on curative one. By this way, kefir as a beverage with highly antioxidant properties could be relevant particularly with the emergent demand for natural products which may counteract the detrimental effects of oxidative stress and therefore prevent multiple human diseases.

Acute triflumuron exposure induces oxidative stress responses in liver and kidney of Balb/C mice.

Triflumuron (TFM) is one of the most widely used insecticides over the world. It is a benzoylphenyl urea that belongs to the class of insect growth regulators. This insecticide acts by inhibiting insect's chitin synthesis and by consequences, making insect more susceptible to pathogens and malformations. TFM effects have been reported in mammalians and crops. However, studies that reveal its toxicity mechanisms are limited. In this line, the current study aimed to determine the implication of oxidative stress in the toxicity induced by TFM and particularly in the perturbation of biochemical parameters in male Balb/C mice. Male Balb/C mice were divided into three groups receiving TFM at doses of 250, 350, and 500 mg/kg bw respectively. The occurrence of oxidative stress in both kidney and liver tissues was monitored by measuring of oxidative stress markers. TFM caused an increase as protein carbonyls generation, malondialdehyde induction (MDA) and catalase (CAT), superoxide dismutase (SOD), glutathion peroxidase (Gpx), as well as glutathion S transferase (GST) activities. In the same conditions, we have evaluated the effect of TFM treatment on biochemical parameters. In response to the three TFM doses, we showed significant dose dependent inductions in all tested oxidative stress markers. However, TFM caused an increase in the liver enzyme activities as aspartate transaminase (AST), alanine transaminase (ALT), alkaline phosphatase (ALP), g-glutamyltranspeptidase (GTT), and total bilirubin (BILT) in a dose-dependent manner. Equally, renal markers as urea, uric acid, albumin, and creatinine were increased in the same manner. We can conclude that oxidative damage seems to be a key determinant of TFM-induced toxicity in both liver and kidney of male Balb/C mice. Moreover, the oxidative stress is more pronounced in the liver than in the kidney. Thus, TFM may be considered as a hepatotoxic insecticide.

[Diagnostic accuracy, limits and practical implications of Multidetector Computed Tomography Coronarography. About 105 cases]. / Performances, limites et implications pratiques du coroscanner. A propos de 105 cas.

BACKGROUND: Non-invasive examination of coronary artery disease is an attractive and rapidly evolving possibility. In certain clinical situations ,multi-detector computed tomography coronarography (MDCT) is currently considered as a promising technique alternative to conventional coronary angiography (CCA). PURPOSE: We suggest from our personal study and from a review of the literature, to analyze diagnostic accuracy of MDCT , its limits and to deduct, its practical implications and its indications. METHODS: 105 patients underwent 64-slice MDCT . Coronary angiography was performed every time when the MDCT was pathologic. In two cases the MDCT was realized in complement of inconclusive coronary angiography .Study of coronary arteries was based on "per -segment" and "per- patients" analyse Results : The mean age was 63,3 years., sex ratio was 0 ,7. Hypertension was noted in 63% of cases 29 ,9 % of patients had mellitus diabetes.The initial clinical presentation was unusual chest pain in 46 patients, exercise chest pain in 40 cases. the MDCT was done for the detection of silent ischemia In 5 cases, for screening of CAD in patients with dilated cardiomyopathy in 5 cases , before cardiac surgery in 3 case and before non cardiac surgery in 2 cases. MDCT was normal in 30 patients ( 28% ) so coronary angiography was avoided in 60% of patients with unusual chest pain, and in 50% of patients with dilated cardiomyopathy and in also in 50% of patients selected for cardiac or non cardiac surgery. In per-segment study the sensitivity, specificity, positive and negative predictive value of the MDCT in detecting coronary stenosis were respectively 89 %,98% , 91% and 97% versus, 98%,89%,94%, 95% the per-patient evaluation .The MDCT was inclusive in10 patients because .of calcifications in 8 cases and because uncontrolled unchecked heart rate in 40 cases Conclusion : our results for negative predictive value of MDCT are similar to reports from the literature. This suggests that in this clinical setting , MDCT may replace coronary in patients with low probability of coronary artery diseases, its is also useful for assessment of cardiomyopathy and before cardiac or non cardiac surgery.

Cytotoxicity effects of amiodarone on cultured cells.

Amiodarone is a potent anti-arrhythmic drug used for the treatment of cardiac arrhythmias. Although, the effects of amiodarone are well characterized on post-ischemic heart and cardiomyocytes, its toxicity on extra-cardiac tissues is still poorly understood. To this aim, we have monitored the cytotoxicity effects of this drug on three cultured cell lines including hepatocytes (HepG2), epithelial cells (EAhy 926) and renal cells (Vero). We have investigated the effects of amiodarone on (i) cell viabilities, (ii) heat shock protein expressions (Hsp 70) as a parameter of protective and adaptive response and (iii) oxidative damage.Our results clearly showed that amiodarone inhibits cell proliferation, induces an over-expression of Hsp 70 and generates significant amount of reactive oxygen species as measured by lipid peroxidation occurrence. However, toxicity of amiodarone was significantly higher in renal and epithelial cells than in hepatocytes. Vitamin E supplement restores the major part of cell mortalities induced by amiodarone showing that oxidative damage is the predominant toxic effect of the drug.Except its toxicity for the cardiac system, our findings demonstrated that amiodarone can target other tissues. Therefore, kidneys present a high sensibility to this drug which may limit its use with subjects suffering from renal disorders.

Hsp70 expression as biomarkers of oxidative stress: mycotoxins' exploration.

The environment represents a key contributor to human health and disease. Exposure to many substances such as pollutants, toxins and chemicals, has detrimental effects on health and are considered to contribute substantially to most diseases of major public health significance. Environmental diseases as mycotoxicosis are those in general aroused or exacerbated by exposure to environmental stressors as mycotoxins. These hazardous compounds are secondary metabolites produced by fungi and occurred simultaneously in food, feed and raw materials. The present investigation was conducted to assess if (i) Hsp70 induction, a parameter of protective and adaptive response, is a systematic biomarker to mycotoxin intoxications and (ii) all mycotoxins undergo oxidative stress in there toxic signalling pathways, as the omnipresent process playing a role in the initiation or progression of numerous disorders. Overall, observations to date evoke that Hsp70 can act as biomarkers of oxidative injury instead they are not systematic to mycotoxin exposure.

Cytotoxic effects exerted by polyarylsulfone dialyser membranes depend on different sterilization processes.

Polyarylsulfone group is one of the most important polymeric materials used in the biomedical field, due to its excellent properties, such as good thermal, chemical, and mechanical stability. There are three important polyarylsulfone polymers, all of which have excellent electrical properties: polysulfone (PSu), polyarylsulfone (PAS) and polyarylethersulfone (PAES). All these polymers have excellent creep, radiation and high temperature resistance. In this study, we aimed to determine the effect of three sterilization processes (steam, ethylene oxide and gamma rays) on cytotoxicity of polyarylsulfone dialysis membranes. Ten long-term dialysis patients and ten age-matched healthy controls were enrolled in our study. We analysed (1) serum effect on cultured endothelial cell viability using MTT assay and (2) lipid peroxidation assessed by serum malondialdehyde (MDA) formation at the beginning (T0), the middle (T2) and the end (T4) of haemodialysis (HD) session. Our results clearly showed that steam-sterilized membranes improve endothelial cell viability when compared to ethylene oxide or gamma rays-sterilized ones. Moreover, there is a increased generation of MDA in patients sera during HD session. The serum MDA concentration was about 3, 6 and 10 times higher, respectively, for steam, ethylene oxide and gamma rays sterilization procedures when compared to the MDA amount in healthy subject sera. We concluded that using steam instead of ethylene oxide or gamma rays for sterilization may improve the biocompatibility of polyarylsulfone membranes.

Echocardiographic assessment of left ventricular dyssynchrony and correlation with QRS width in chronic heart failure.

BACKGROUND: Echocardiographic parameters of mechanical dyssynchrony may improve patients selection for cardiac resynchronisation therapy in chronic heart failure. AIM: This study aimed to define the prevalence of inter, intra and atrio-ventricular dyssynchrony in heart failure patients with different QRS duration and to evaluate inter and intra-observer variability in collecting different echocardiographic dyssynchony parameters. METHODS: Twenty patients with chronic heart failure of any origin, NYHA functional class II-III with LVEF < 40%, were evaluated by complete echocardiographic examination including tissue Doppler imaging (DTI) and Tissue Tracking. RESULTS: Three patients had an atrio-ventricular dyssynchrony with a mean left ventricular filling time to cardiac cycle of 33 +/- 5%. Six patients had an interventricular mechanical delay (IVMD) > or = 40 milliseconds, all of them had a QRS duration > or = 120 milliseconds. Overall, no statistically significant correlation was found between IVMD and QRS duration (r = 0.35, p = 0.4). The mean septal to posterior wall-motion delay (SPWMD) was 83 +/- 64 ms. 7 patients had SPWMD > or = 130 ms. The baseline QRS duration did not correlate with SPWMD (p = 0.7). The mean LV dyssynchrony determined by deltaS-peak was 74 +/- 42 ms. Seven patients had LV dyssynchrony. Linear regression did not demonstrate a relation between QRS width and intraventricular dyssynchrony (p = 0.34). There was no concordance between intra-ventricular spatial or longitudinal dyssynchrony determined by DTI method and by Tissue Tracking (p = 0.3 and 0.6 respectively). The intraobserver reproducibility of LVFT/RR, IVMD and deltaS-peak (ICC = 0.99, 0.98 and 0.99, respectively), as well as the interobserver reproducibility (ICC: 0.96, 0.94 and 0.92, respectively), were very high. However, we observed a high variability for SPWMD measure (ICC = 0.27, p = 0.31). CONCLUSION: Mechanical dyssynchrony did not correlate with QRS duration, despite the poor variability in collecting different echocardiographic parameters.

Cytotoxicity and genotoxicity induced by aflatoxin B1, ochratoxin A, and their combination in cultured Vero cells.

Aflatoxin B1 (AFB1) and ochratoxin A (OTA) are important food-borne mycotoxins that have been implicated in human health. In this study, independent and combinative toxicities of AFB1 and OTA were tested in cultured monkey kidney Vero cells. The experiments reported here were conducted to evaluate the effect of these toxins on cell viability followed by the determination of cell death pathways, using the quantification of DNA fragmentation and the expression of p53 and bcl-2 protein levels. Our results showed that AFB1 and OTA caused a marked decrease of cell viability in a dose-dependent manner. Under the same conditions, these mycotoxins increased fragmented DNA levels. In addition, p53 was activated in response to DNA damage and the expression of the antiapoptotic factor bcl-2 decreased significantly. According to these data, AFB1 and OTA seemed to be involved in an apoptotic process. Moreover, combined AFB1 and OTA induced all the toxicities observed with the mycotoxins separately. Therefore, this combination was classified as an additive response of the two mycotoxins.

Sequential events of apoptosis induced by zearalenone in cultured hepatocarcinoma cells.

Zearalenone (ZEA) is a fungal metabolite that can contaminate feed and foodstuffs and can cause serious health problems for animals as well as for humans. The present investigation was conducted to determine the chronological succession of the main events that characterise ZEA-induced toxicity in human hepatocarcinoma cells. To this aim, we have monitored the effects of ZEA on (1) cell viability, (2) heat-shock protein expression, (3) oxidative damage, (4) DNA fragmentation, (5) the cell cycle and (6) the cell-death-signalling pathway. Our results demonstrated that ZEA reduced cell viability in a time- and dose-dependent manner. When we exposed HepG2 cells to 100 µM ZEA (80% of cells are viable) for different treatment times (2, 4, 8, 24, 30, 48 and 60 h), we demonstrated an induction of Hsp70 protein, an increase in reactive oxygen species (ROS) generation, DNA fragmentation and cell-cycle arrest. These events begin after only 2 h of mycotoxin exposure and are earlier than those implicated in the execution of apoptosis. However, significant apoptotic cell death was observed after at least 30 h of ZEA exposure as a consequence of increased Bax expression, decreased Bcl-2 expression and mitochondrial membrane potential (Δψm)-released cytochrome c and activated caspase-3 and caspase-9.

[Determination of mitral valve area in patients with mitral stenosis by the flow-convergence method: clinical application]. / Evaluation de la surface mitrale par la méthode de la zone de convergence dans le rétrécissement mitral: application clinique.

BACKGROUND: Classic echocardiographic methods to estimate mitral valve area (MVA) in the mitral stenosis (MS) has several limitations. Recently, the proximal isovelocity surface area (PISA) method has been shown to be accurate for calculating MVA. AIMS: This study sought to 1) compare the accuracy of the PISA method to planimetry and Doppler pressure half-time (PHT) methods for echocardiographic estimation of MVA and 2) to evaluate the effect of atrial fibrillation (AF) and significant mitral regurgitation (MR) on the accuracy of the PISA method. METHODS: In 35 patients with rheumatic mitral stenosis, the mitral valve areas were determined by two-dimensional echocardiographic planimetry, pressure half-time and proximal flow convergence region. 19 patients had atrial fibrillation and 15 had associated mitral insufficiency > or = 2. RESULTS: The correlaton between PISA and planimetry areas was significant (r=0.83, p<.001). The intraclass correlation coefficient was of 0.85 but with a large confidence interval (IC 95% [0,68-0,9]) explaining the significant underestimation of MVA by PISA method: 1,42 +/- 0,47 cm2 versus 1,56 +/- 0,41 cm2 respectively, (p<.001). There was no signicant difference between PISA and PHT areas : 1,42 +/- 0,47 cm2 versus 1,43 +/- 0,46 cm2. Underestimation of MVA par PISA method didn't have real clinical implication: the sensibility of diagnosing severe MS (MVA < or = 1.5 cm2) was 90% vith a negative predictive value of 83%. The correlation was good in patients with AF (r=0,84, p<.001) and with significant MR (r=0,83, p<.001). CONCLUSION: The PISA method may be considered as reliable alternative method for estimation of the MVA in MS. Its accuracy is good in AF and associated MR.

Pathway of deoxynivalenol-induced apoptosis in human colon carcinoma cells.

The mycotoxin, deoxynivalenol (DON), is generally detected in cereal grains and grain-based food products worldwide. Therefore, DON has numerous toxicological effects on animals and humans. The present investigation was conducted to determine the molecular aspects of DON toxicity on human colon carcinoma cells (HT 29). To this aim, we have monitored the effects of DON on (i) cell viability, (ii) Heat shock protein expressions as a parameter of protective and adaptive response, (iii) oxidative damage and (iv) cell death signalling pathway. Our results clearly showed that DON treatment inhibits cell proliferation, did not induce Hsp 70 protein expression and reactive oxygen species generation. We have also demonstrated that this toxin induced a DNA fragmentation followed by p53 and caspase-3 activations. Finally, our findings suggested that oxidative damage is not the major contributor to DON toxicity. This mycotoxin induces direct DNA lesions and could be considered by this fact as a genotoxic agent inducing cell death via an apoptotic process.

Toxicities induced in cultured human hepatocarcinoma cells exposed to ochratoxin A: oxidative stress and apoptosis status.

Ochratoxin A (OTA) is a mycotoxin currently detected in stored animal and human food supplies as well as in human sera worldwide. OTA has diverse toxicological effects; however, the most prominent one is the nephrotoxicity. The present investigation was conducted to determine the molecular aspects of OTA toxicity in cultured human hepatocellular carcinoma cells. With this aim, we have monitored the effects of OTA on (i) cell viability, (ii) heat shock protein expressions as a parameter of protective and adaptive response, (iii) oxidative damage, and (iv) cell death signaling pathway. Our results clearly showed that OTA treatment inhibits cell proliferation, downregulates Hsp 70 and Hsp 27 protein and mRNA levels, and did not induce a significant reactive oxygen species generation. We have also demonstrated a decrease in mitochondrial membrane potential, a cytochrome c release, and an activation of caspase 9 and caspase 3 in response to OTA exposure. Moreover, OTA activates p53 expression, while some of its transcriptional target genes (Bax, Bak, PUMA, and p21) were found to downregulate. According to these data, we concluded that OTA may exert an inhibitory action on the transcriptional process. Besides, oxidative damage is not a major contributor to OTA toxicity. This mycotoxin induces a mitochondrial and caspase-dependent apoptotic cell death, which seems to be mediated by p53 transcriptional independent activities.