Physiological role of reactive oxygen species as promoters of natural defenses.

It has been 60 yr since the discovery of reactive oxygen species (ROS) in biology and the beginning of the scientific community's attempt to understand the impact of the unpaired electron of ROS molecules in biological pathways, which was eventually noted to be toxic. Several studies have shown that the presence of ROS is essential in triggering or acting as a secondary factor for numerous pathologies, including metabolic and genetic diseases; however, it was demonstrated that chronic treatment with antioxidants failed to show efficacy and positive effects in the prevention of diseases or health complications that result from oxidative stress. On the contrary, such treatment has been shown to sometimes even worsen the disease. Because of the permanent presence of ROS in organisms, elaborate mechanisms to adapt with these reactive molecules and to use them without necessarily blocking or preventing their actions have been studied. There is now a large body of evidence that shows that living organisms have conformed to the presence of ROS and, in retrospect, have adapted to the bioactive molecules that are generated by ROS on proteins, lipids, and DNA. In addition, ROS have undergone a shift from being molecules that invoked oxidative damage in regulating signaling pathways that impinged on normal physiological and redox responses. Working in this direction, this review unlocks a new conception about the involvement of cellular oxidants in the maintenance of redox homeostasis in redox regulation of normal physiological functions, and an explanation for its essential role in numerous pathophysiological states is noted.-Roy, J., Galano, J.-M., Durand, T., Le Guennec, J.-Y., Lee, J. C.-Y. Physiological role of reactive oxygen species as promoters of natural defenses.

Cardioprotective effects of omega 3 fatty acids: origin of the variability.

Since 40 years, it is known that omega-3 poly-unsaturated fatty acids (ω3 PUFAs) have cardioprotective effects. These include antiarrhythmic effects, improvements of autonomic function, endothelial function, platelet anti-aggregation and inflammatory properties, lowering blood pressure, plaque stabilization and reduced atherosclerosis. However, recently, conflicting results regarding the health benefits of ω3 PUFAs from seafood or ω3 PUFAs supplements have emerged. The aim of this review is to examine recent literature regarding health aspects of ω3 PUFAs intake from fish or supplements, and to discuss different arguments/reasons supporting these conflicting findings.

Non-enzymatic cyclic oxygenated metabolites of adrenic, docosahexaenoic, eicosapentaenoic and α-linolenic acids; bioactivities and potential use as biomarkers.

Cyclic oxygenated metabolites are formed in vivo through non-enzymatic free radical reaction of n-6 and n-3 polyunsaturated fatty acids (PUFAs) such as arachidonic (ARA C20:4 n-6), adrenic (AdA 22:4 n-6), α-linolenic (ALA 18:3 n-3), eicosapentaenoic (EPA 20:5 n-3) and docosahexaenoic (DHA 22:6 n-3) acids. These cyclic compounds are known as isoprostanes, neuroprostanes, dihomo-isoprostanes and phytoprostanes. Evidence has emerged for their use as biomarkers of oxidative stress and, more recently, the n-3PUFA-derived compounds have been shown to mediate bioactivities as secondary messengers. Accordingly, this review will focus on the cyclic oxygenated metabolites generated from AdA, ALA, EPA and DHA. This article is part of a Special Issue entitled "Oxygenated metabolism of PUFA: analysis and biological relevance".

Ranolazine inhibits NaV1.5-mediated breast cancer cell invasiveness and lung colonization.

BACKGROUND: Na(V)1.5 voltage-gated sodium channels are abnormally expressed in breast tumours and their expression level is associated with metastatic occurrence and patients' death. In breast cancer cells, Na(V)1.5 activity promotes the proteolytic degradation of the extracellular matrix and enhances cell invasiveness. FINDINGS: In this study, we showed that the extinction of Na(V)1.5 expression in human breast cancer cells almost completely abrogated lung colonisation in immunodepressed mice (NMRI nude). Furthermore, we demonstrated that ranolazine (50 µM) inhibited Na(V)1.5 currents in breast cancer cells and reduced Na(V)1.5-related cancer cell invasiveness in vitro. In vivo, the injection of ranolazine (50 mg/kg/day) significantly reduced lung colonisation by Na(V)1.5-expressing human breast cancer cells. CONCLUSIONS: Taken together, our results demonstrate the importance of Na(V)1.5 in the metastatic colonisation of organs by breast cancer cells and indicate that small molecules interfering with Na(V) activity, such as ranolazine, may represent powerful pharmacological tools to inhibit metastatic development and improve cancer treatments.

In silico modelling of stroke volume, cardiac output and systemic vascular resistance in cardiovascular safety pharmacology studies by telemetry.

The principle of proportionality of the systolic area of the central aortic pressure to stroke volume (SV) has been long known. The aim of the present work was to evaluate an in silico solution derived from this principle for modelling SV (iSV model) in cardiovascular safety pharmacology studies by telemetry. Blood pressure was measured in the abdominal aorta in accordance with standard practice. Central aortic pressure was modelled from the abdominal aortic pressure waveform using the N-point moving average (NPMA) method for beat-to-beat estimation of SV. First, the iSV was compared to the SV measured by ultrasonic flowmetry in the ascending aorta (uSV) after various pharmacological challenges in beagle dogs anaesthetised with etomidate/fentanyl. The iSV showed minimal bias (0.2 mL i.e. 2%) and excellent agreement with uSV. Then, previous telemetry studies including reference vasoactive and inotropic compounds were retrospectively reanalysed to model drug effects on stroke volume (iSV), cardiac output (iCO) and systemic vascular resistance (iSVR). Among them, the examples of nicardipine and isoprenaline highlight risks of erroneous or biased estimation of drug effects from the abdominal aortic pressure due to pulse pressure amplification. Furthermore, the examples of verapamil, quinidine and moxifloxacin show that iSV, iCO and iSVR are earlier biomarkers than blood pressure itself for predicting drug effect on blood pressure. This in silico modelling approach included in vivo telemetry safety pharmacology studies can be considered as a New Approach Methodology (NAM) that provides valuable additional information and contribute to improving non-clinical translational research to the clinic.

Activation of hTREK-1 by polyunsaturated fatty acids involves direct interaction.

TREK-1 is a mechanosensitive channel activated by polyunsaturated fatty acids (PUFAs). Its activation is supposed to be linked to changes in membrane tension following PUFAs insertion. Here, we compared the effect of 11 fatty acids and ML402 on TREK-1 channel activation using the whole cell and the inside-out configurations of the patch-clamp technique. Firstly, TREK-1 activation by PUFAs is variable and related to the variable constitutive activity of TREK-1. We observed no correlation between TREK-1 activation and acyl chain length or number of double bonds suggesting that the bilayer-couple hypothesis cannot explain by itself the activation of TREK-1 by PUFAs. The membrane fluidity measurement is not modified by PUFAs at 10 µM. The spectral shift analysis in TREK-1-enriched microsomes indicates a KD,TREK1 at 44 µM of C22:6 n-3. PUFAs display the same activation and reversible kinetics than the direct activator ML402 and activate TREK-1 in both whole-cell and inside-out configurations of patch-clamp suggesting that the binding site of PUFAs is accessible from both sides of the membrane, as for ML402. Finally, we proposed a two steps mechanism: first, insertion into the membrane, with no fluidity or curvature modifications at 10 µM, and then interaction with TREK-1 channel to open it.

From MS/MS library implementation to molecular networks: Exploring oxylipin diversity with NEO-MSMS.

Oxylipins, small polar molecules derived from the peroxidation of polyunsaturated fatty acids (PUFAs), serve as biomarkers for many diseases and play crucial roles in human physiology and inflammation. Despite their significance, many non-enzymatic oxygenated metabolites of PUFAs (NEO-PUFAs) remain poorly reported, resulting in a lack of public datasets of experimental data and limiting their dereplication in further studies. To overcome this limitation, we constructed a high-resolution tandem mass spectrometry (MS/MS) dataset comprising pure NEO-PUFAs (both commercial and self-synthesized) and in vitro free radical-induced oxidation of diverse PUFAs. By employing molecular networking techniques with this dataset and the existent ones in public repositories, we successfully mapped a wide range of NEO-PUFAs, expanding the strategies for annotating oxylipins, and NEO-PUFAs and offering a novel workflow for profiling these molecules in biological samples.

Isoprostanes and neuroprostanes: total synthesis, biological activity and biomarkers of oxidative stress in humans.

Isoprostanes (IsoPs) and neuroprostanes (NeuroPs) are formed in vivo by a free radical non-enzymatic mechanism involving peroxidation of arachidonic acid (AA, C20:4 n-6) and docosahexaenoic acid (DHA, C22:6 n-3) respectively. This review summarises our research in the total synthesis of these lipid metabolites, as well as their biological activities and their utility as biomarkers of oxidative stress in humans.

Genotyping and antimicrobial resistance of Staphylococcus aureus isolates from diseased turkeys.

Staphylococcus aureus is a highly versatile pathogen in a large number of domestic animals, including avian species. To gain deeper insight into the epidemiology and diversity of S. aureus associated with articular disease in domestic turkeys, isolates were collected from infected foot joints of turkeys in Brittany (France). A total of 34 isolates were recovered and characterized by means of antimicrobial resistance, staphylococcal protein A typing, macrorestriction pulsed-field gel electrophoresis and micro-array analysis. Thirty isolates were identified as clonal complex (CC) 398 and methicillin-susceptible S. aureus (MSSA), one was identified as a methicillin-resistant S. aureus (MRSA) CC398 isolate, and the remaining were also MSSA and belonged to CC5, CC101, and CC121. Eleven different antimicrobial resistance patterns were detected, with most isolates resistant to penicillin and tetracycline. Based on all typing methods used, the 34 isolates could be divided into 22 different strains. Results on selected isolates, genotyped using microarrays, indicated a high homogeneity among pathogenic MSSA isolates from turkeys. Moreover, all isolates, except the unique MRSA isolate, carried specific φAvß prophage avian-niche-specific genes, demonstrating the versatility of S. aureus to adapt to the specific ecological poultry niche.

Comparative Genome Analysis of Enterococcus cecorum Reveals Intercontinental Spread of a Lineage of Clinical Poultry Isolates.

Enterococcus cecorum is an emerging pathogen responsible for osteomyelitis, spondylitis, and femoral head necrosis causing animal suffering and mortality and requiring antimicrobial use in poultry. Paradoxically, E. cecorum is a common inhabitant of the intestinal microbiota of adult chickens. Despite evidence suggesting the existence of clones with pathogenic potential, the genetic and phenotypic relatedness of disease-associated isolates remains little investigated. Here, we sequenced and analyzed the genomes and characterized the phenotypes of more than 100 isolates, the majority of which were collected over the last 10 years from 16 French broiler farms. Comparative genomics, genome-wide association studies, and the measured susceptibility to serum, biofilm-forming capacity, and adhesion to chicken type II collagen were used to identify features associated with clinical isolates. We found that none of the tested phenotypes could discriminate the origin of the isolates or the phylogenetic group. Instead, we found that most clinical isolates are grouped phylogenetically, and our analyses selected six genes that discriminate 94% of isolates associated with disease from those that are not. Analysis of the resistome and the mobilome revealed that multidrug-resistant clones of E. cecorum cluster into a few clades and that integrative conjugative elements and genomic islands are the main carriers of antimicrobial resistance. This comprehensive genomic analysis shows that disease-associated clones of E. cecorum belong mainly to one phylogenetic clade. IMPORTANCE Enterococcus cecorum is an important pathogen of poultry worldwide. It causes a number of locomotor disorders and septicemia, particularly in fast-growing broilers. Animal suffering, antimicrobial use, and associated economic losses require a better understanding of disease-associated E. cecorum isolates. To address this need, we performed whole-genome sequencing and analysis of a large collection of isolates responsible for outbreaks in France. By providing the first data set on the genetic diversity and resistome of E. cecorum strains circulating in France, we pinpoint an epidemic lineage that is probably also circulating elsewhere that should be targeted preferentially by preventive strategies in order to reduce the burden of E. cecorum-related diseases.

Contribution of haemodynamic side effects and associated autonomic reflexes to ventricular arrhythmias triggering by torsadogenic hERG blocking drugs.

BACKGROUND AND PURPOSE: HERG blocking drugs known for their propensity to trigger Torsades de Pointes (TdP) were reported to induce a sympatho-vagal coactivation and to enhance High Frequency heart rate (HFHR) and QT oscillations (HFQT) in telemetric data. The present work aimed to characterize the underlying mechanism(s) leading to these autonomic changes. EXPERIMENTAL APPROACH: Effects of 15 torsadogenic hERG blocking drugs (astemizole, chlorpromazine, cisapride, droperidol, ibutilide, dofetilide, haloperidol, moxifloxacin, pimozide, quinidine, risperidone, sotalol, sertindole, terfenadine, and thioridazine) were assessed by telemetry in beagle dogs. Haemodynamic effects on diastolic and systolic arterial pressure were analysed from the first doses causing QTc prolongation and/or HFQT oscillations enhancement. Autonomic control changes were analysed using the high frequency autonomic modulation (HFAM) model. KEY RESULTS: Except for moxifloxacin and quinidine, all torsadogenic hERG blockers induced parasympathetic activation or sympatho-vagal coactivation combined with enhancement of HFQT oscillations. These autonomic effects result from reflex compensatory mechanisms in response to mild haemodynamic side effects. These haemodynamic mechanisms were characterized by transient HR acceleration during HF oscillations. A phenomenon of concealed QT prolongation was unmasked for several torsadogenic hERG blockers under ß-adrenoceptor blockade with atenolol. Resulting enhancement of HFQT oscillations was shown to contribute directly to triggering dofetilide-induced ventricular arrhythmias. CONCLUSION AND IMPLICATIONS: This work supports for the first time a contribution of haemodynamic side properties to ventricular arrhythmias triggered by torsadogenic hERG blocking drugs. These haemodynamic side effects may constitute a second component of their arrhythmic profile, acting as a trigger alongside their intrinsic arrhythmogenic electrophysiological properties.

TREK-1 in the heart: Potential physiological and pathophysiological roles.

The TREK-1 channel belongs to the TREK subfamily of two-pore domains channels that are activated by stretch and polyunsaturated fatty acids and inactivated by Protein Kinase A phosphorylation. The activation of this potassium channel must induce a hyperpolarization of the resting membrane potential and a shortening of the action potential duration in neurons and cardiac cells, two phenomena being beneficial for these tissues in pathological situations like ischemia-reperfusion. Surprisingly, the physiological role of TREK-1 in cardiac function has never been thoroughly investigated, very likely because of the lack of a specific inhibitor. However, possible roles have been unraveled in pathological situations such as atrial fibrillation worsened by heart failure, right ventricular outflow tract tachycardia or pulmonary arterial hypertension. The inhomogeneous distribution of TREK-1 channel within the heart reinforces the idea that this stretch-activated potassium channel might play a role in cardiac areas where the mechanical constraints are important and need a particular protection afforded by TREK-1. Consequently, the main purpose of this mini review is to discuss the possible role played by TREK -1 in physiological and pathophysiological conditions and its potential role in mechano-electrical feedback. Improved understanding of the role of TREK-1 in the heart may help the development of promising treatments for challenging cardiac diseases.

The Effect of Hypothermia and Osmotic Shock on the Electrocardiogram of Adult Zebrafish.

The use of zebrafish to explore cardiac physiology has been widely adopted within the scientific community. Whether this animal model can be used to determine drug cardiac toxicity via electrocardiogram (ECG) analysis is still an ongoing question. Several reports indicate that the recording configuration severely affects the ECG waveforms and its derived-parameters, emphasizing the need for improved characterization. To address this problem, we recorded ECGs from adult zebrafish hearts in three different configurations (unexposed heart, exposed heart, and extracted heart) to identify the most reliable method to explore ECG recordings at baseline and in response to commonly used clinical therapies. We found that the exposed heart configuration provided the most reliable and reproducible ECG recordings of waveforms and intervals. We were unable to determine T wave morphology in unexposed hearts. In extracted hearts, ECG intervals were lengthened and P waves were unstable. However, in the exposed heart configuration, we were able to reliably record ECGs and subsequently establish the QT-RR relationship (Holzgrefe correction) in response to changes in heart rate.

L-Type Cav1.3 Calcium Channels Are Required for Beta-Adrenergic Triggered Automaticity in Dormant Mouse Sinoatrial Pacemaker Cells.

BACKGROUND: Sinoatrial node cells (SANC) automaticity is generated by functional association between the activity of plasmalemmal ion channels and local diastolic intracellular Ca2+ release (LCR) from ryanodine receptors. Strikingly, most isolated SANC exhibit a "dormant" state, whereas only a fraction shows regular firing as observed in intact SAN. Recent studies showed that ß-adrenergic stimulation can initiate spontaneous firing in dormant SANC, though this mechanism is not entirely understood. METHODS: To investigate the role of L-type Cav1.3 Ca2+ channels in the adrenergic regulation of automaticity in dormant SANC, we used a knock-in mouse strain in which the sensitivity of L-type Cav1.2 α1 subunits to dihydropyridines (DHPs) was inactivated (Cav1.2DHP-/-), enabling the selective pharmacological inhibition of Cav1.3 by DHPs. RESULTS: In dormant SANC, ß-adrenergic stimulation with isoproterenol (ISO) induced spontaneous action potentials (AP) and Ca2+ transients, which were completely arrested with concomitant perfusion of the DHP nifedipine. In spontaneously firing SANC at baseline, Cav1.3 inhibition completely reversed the effect of ß-adrenergic stimulation on AP and the frequency of Ca2+ transients. Confocal calcium imaging of SANC showed that the ß-adrenergic-induced synchronization of LCRs is regulated by the activity of Cav1.3 channels. CONCLUSIONS: Our study shows a novel role of Cav1.3 channels in initiating and maintaining automaticity in dormant SANC upon ß-adrenergic stimulation.

Toxic Effects of Fumonisins, Deoxynivalenol and Zearalenone Alone and in Combination in Ducks Fed the Maximum EUTolerated Level.

Toxic effects among fumonisins B (FB), deoxynivalenol (DON) and zearalenone (ZEN) administered alone and combined were investigated in 84-day-old ducks during force-feeding. 75 male ducks, divided into five groups of 15 animals, received daily during the meal a capsule containing the desired among of toxin. Treated animals received dietary levels of toxins equivalent to 20 mg FB1+FB2/kg (FB), 5 mg DON/kg (DON), 0.5 mg ZEN/kg (ZEN) and 20, 5 and 0.5 mg/kg of FB, DON and ZEN (FBDONZEN), respectively. Control birds received capsules with no toxin. After 12 days, a decrease in body weight gain accompanied by an increase in the feed conversion ratio was observed in ducks exposed to FBDONZEN, whereas there was no effect on performances in ducks exposed to FB, DON and ZEN separately. No difference among groups was observed in relative organ weight, biochemistry, histopathology and several variables used to measure oxidative damage and testicular function. A sphinganine to sphingosine ratio of 0.32, 1.19 and 1.04, was measured in liver in controls and in ducks exposed to FB and FBDONZEN, respectively. Concentrations of FB1 in liver were 13.34 and 15.4 ng/g in ducks exposed to FB and FBDONZEN, respectively. Together ZEN and its metabolites were measured after enzymatic hydrolysis of the conjugated forms. Mean concentrations of α-zearalenol in liver were 0.82 and 0.54 ng/g in ducks exposed to ZEN and FBDONZEN, respectively. ß-zearalenol was 2.3-fold less abundant than α-zearalenol, whereas ZEN was only found in trace amounts. In conclusion, this study suggests that decreased performance may occur in ducks exposed to a combination of FB, DON and ZEN, but does not reveal any other interaction between mycotoxins in any of the other variables measured.

New role of TRPM4 channel in the cardiac excitation-contraction coupling in response to physiological and pathological hypertrophy in mouse.

The transient receptor potential Melastatin 4 (TRPM4) channel is a calcium-activated non-selective cation channel expressed widely. In the heart, using a knock-out mouse model, the TRPM4 channel has been shown to be involved in multiple processes, including ß-adrenergic regulation, cardiac conduction, action potential duration and hypertrophic adaptations. This channel was recently shown to be involved in stress-induced cardiac arrhythmias in a mouse model overexpressing TRPM4 in ventricular cardiomyocytes. However, the link between TRPM4 channel expression in ventricular cardiomyocytes, the hypertrophic response to stress and/or cellular arrhythmias has yet to be elucidated. In this present study, we induced pathological hypertrophy in response to myocardial infarction using a mouse model of Trpm4 gene invalidation, and demonstrate that TRPM4 is essential for survival. We also demonstrate that the TRPM4 is required to activate both the Akt and Calcineurin pathways. Finally, using two hypertrophy models, either a physiological response to endurance training or a pathological response to myocardial infarction, we show that TRPM4 plays a role in regulating transient calcium amplitudes and leads to the development of cellular arrhythmias potentially in cooperation with the Sodium-calcium exchange (NCX). Here, we report two functions of the TRPM4 channel: first its role in adaptive hypertrophy, and second its association with NCX could mediate transient calcium amplitudes which trigger cellular arrhythmias.

Non-anti-mitotic concentrations of taxol reduce breast cancer cell invasiveness.

Taxol is widely used in breast cancer chemotherapy. Its effects are primarily attributed to its anti-mitotic activity. Microtubule perturbators also exert antimetastatic activities which cannot be explained solely by the inhibition of proliferation. Voltage-dependent sodium channels (Na(V)) are abnormally expressed in the highly metastatic breast cancer cell line MDA-MB-231 and not in MDA-MB-468 cell line. Inhibiting Na(V) activity with tetrodotoxin is responsible for an approximately 0.4-fold reduction of MDA-MB-231 cell invasiveness. In this study, we focused on the effect of a single, 2-h application of 10 nM taxol on the two cell lines MDA-MB-231 and MDA-MB-468. At this concentration, taxol had no effect on proliferation after 7 days and on migration in any cell line. However it led to a 40% reduction of transwell invasion of MDA-MB-231 cells. There was no additive effect when taxol and tetrodotoxin were simultaneously applied. Na(V) activity, as assessed by patch-clamp, indicates that it was changed by taxol pre-treatment. We conclude that taxol can exert anti-tumoral activities, in cells expressing Na(V), at low doses that have no effect on cell proliferation. This effect might be due to a modulation of signalling pathways involving sodium channels.

Monitoring PRRSV-1 in suckling piglets in an endemic herd using reverse transcriptase quantitative real time polymerase chain reaction: comparison of the rate of detection in serum and oral fluid samples and evaluation of pooling.

BACKGROUND: Defining shedding and exposure status for PRRSV is essential in herd stabilisation protocols and weaning-age pigs is a key subpopulation. Oral fluid (OF) sampling is a welfare-friendly and cost saving promising alternative to blood sampling. The first objective of our study was to compare the rate of detection of PRRSV-1 in individual serum sample, individual OF sample, litter-based OF sample, collected the day before weaning. The second objective was to evaluate the interest of pooling samples. RESULTS: The study was performed on a 210-sows, PRRSV-1 exposed, with confirmed shedding, non-vaccinated against PRRSV, herd. 80 litters were sampled and 26 were viropositive and therefore included. The rate of detection of PRRSV-1 with RT-qrtPCR in blood samples, iOF and cOF was 67, 23 and 77%, respectively. The Ct values from RT-qrtPCR on collective OF were statistically lower if the serum of the piglet of the litter was positive. The lower the Cycle threshold (Ct) value of RT-qrtPCR on collective OF, the higher the probability that the serum sampled in the same litter was positive. Ability to detect PRRSV RNA after pooling was 67% for sera and 58% for cOF. CONCLUSIONS: The rate of detection of PRRSV-1 was about the same in cOF and blood samples. Virus sequencing, if required, should be performed on individual serum samples. The smaller the Ct of a cOF sample from a litter, the greater the likelihood that the serum sample from a piglet of that litter is positive.A cost-effective and representative sampling protocol to monitor sow herds stabilisation of a sow batch could be: to collect both cOF and one serum sample per litter; to perform firstly RT-qrtPCR on pooled cOF; in case of negative results to consider the batch negative; in case of positive results in a unvaccinated herd or a killed vaccine vaccinated one to consider the batch positive; in case of positive result in a herd vaccinated with a modified live vaccine serum samples of litters with positive cOF should be tested for sequencing (selecting the litters with the lowest Ct for cOF).

Toxicity of Fumonisins, Deoxynivalenol, and Zearalenone Alone and in Combination in Turkeys Fed with the Maximum European Union-Tolerated Level.

Surveys of mycotoxins worldwide have shown that deoxynivalenol (DON), fumonisins (FB), and zearalenone (ZON) are the most abundant Fusarium mycotoxins (FUS) in European poultry feed, in both the level and the frequency of contamination. Previous studies reported that a combination of FUS at concentrations that individually are not toxic may negatively affect animals. However, although toxic thresholds and regulatory guidelines exist for FUS, none account for the risk of multiple contamination, which is the most frequent. The aim of this study was to compare DON, FB, and ZON toxicity, alone and in combination, in male turkey poults. Ground cultured toxigenic Fusarium strains were incorporated in corn-soybean-based feed in five experimental diets: control diet, containing no mycotoxins, DON diet (5 mg DON/kg), FB diet (20 mg FB1 + FB2/ kg), ZON diet (0.5 mg ZON/kg), and DONFBZON diet (5, 20, and 0.5 mg/kg of DON, FB1 + FB2, and ZON, respectively). Seventy male Grade Maker turkeys were reared in individual cages on mycotoxin-free diets from 0 to 55 days of age. On the 55th day, the turkeys were weighed and divided into five groups each comprising 14 birds. Each group was fed one of the five experimental diets for a period of 14 days. On the 70th day of age, feed was withheld for 8 hr, at which time a blood sample was collected, and then all the turkeys were killed, autopsied, and different tissues sampled. The weight of the different organs, analyses of performance, biochemistry, histopathology, oxidative damage, and testis toxicity revealed no significant effects attributable to FUS. Measurement of sphingolipids in the liver revealed an increase in the sphinganine to sphingosine ratio in turkeys fed diets containing FB, but had no apparent consequences in terms of toxicity. Finally, only slight differences were found in some variables and the results of this study showed no interactions between DON, FB, and ZON. Taken together, results thus suggest that the maximum tolerated levels established for individual contamination by DON, FB, and ZON can also be considered safe in turkeys fed with combinations of these FUS for a period of 14 days.

Toxicidad de fumonisinas, deoxinivalenol y zearalenona solos y en combinación en pavos alimentados con el nivel máximo tolerado por la Unión Europea. Investigaciones sobre micotoxinas en todo el mundo han demostrado que el deoxinivalenol (DON), las fumonisinas (FB) y la zearalenona (ZON) son las micotoxinas de Fusarium (FUS) más abundantes en la alimentación avícola europea, tanto en el nivel como en la frecuencia de la contaminación. Estudios anteriores informaron que una combinación de micotoxinas de Fusarium a concentraciones que individualmente no son tóxicas puede afectar negativamente a los animales. Sin embargo, aunque existen umbrales tóxicos y pautas regulatorias para las micotoxinas de Fusarium, ninguno tiene en cuenta el riesgo de contaminación múltiple, que es lo más frecuente. El objetivo de este estudio fue comparar la toxicidad deoxinivalenol, fumonisinas, y zearalenona, solas o en combinación en pavos machos. Cepas toxigénicas de Fusarium cultivadas en suelos fueron incorporadas en alimentos a base de maíz y soya en cinco dietas experimentales: dieta de control, que no contiene micotoxinas, dieta DON (5 mg DON/kg), dieta FB (20 mg FB1+FB2/kg), dieta ZON (0.5 mg de ZON/kg) y dieta DONFBZON (5, 20 y 0.5 mg/kg de deoxinivalenol, fumonisinas 1 y 2 y zearalenona, respectivamente). Setenta pavos machos Grado Maker fueron criados en jaulas individuales con dietas libres de micotoxinas de 0 a 55 días de edad. En el día 55, los pavos se pesaron y se distribuyeron en cinco grupos, cada uno con 14 aves. Cada grupo fue alimentado con una de las cinco dietas experimentales durante un período de 14 días. En el día 70 de edad, el alimento se retuvo durante 8 horas, momento en el que se recolectó una muestra de sangre, y luego se sacrificaron todos los pavos, se les realizó la necropsia y se tomaron muestras de diferentes tejidos. El peso de los diferentes órganos, los análisis de rendimiento, la bioquímica, la histopatología, el daño oxidativo y la toxicidad en testículos no revelaron efectos significativos atribuibles a micotoxinas de Fusarium. La medición de esfingolípidos en el hígado reveló un aumento en la relación de esfinganina con relación a la esfingosina en pavos alimentados con dietas que contenían fumonisinas, pero no tuvo consecuencias aparentes en términos de toxicidad. Finalmente, solo se encontraron ligeras diferencias en algunas variables y los resultados de este estudio no mostraron interacciones entre deoxinivalenol, fumonisinas y zearalenona. Tomados en conjunto, los resultados sugieren que los niveles máximos tolerados establecidos para la contaminación individual por deoxinivalenol, fumonisinas y zearalenona también pueden considerarse seguros en pavos alimentados con combinaciones de estas micotoxinas de Fusarium durante un período de 14 días.

Characterization of cell membrane response to ultrasound activated microbubbles.

Contrast agents for ultrasound imaging, composed of tiny gas microbubbles, have become a reality in clinical routine. They are extensively used in radiology for detection and characterization of various tumors and in cardiology for left ventricular opacification. Recent experimental studies showed that ultrasound waves in combination with contrast agent microbubbles increase transiently cell membrane permeability in a process known as sonoporation. This effect is thought to allow foreign molecules to enter the cell. In that context, we explored the cell membrane's responses to microbubbles' oscillations as the mechanism is not completely understood. Breast cancer cell line in combination with contrast microbubbles were used. Ultrasound was applied using a transducer of 1 MHz center frequency transmitting a 10-cycle burst of different acoustic pressures repeated every 100 mus. Patch-clamp technique in whole cell configuration was used to explore transmembrane ion exchange through the variations in membrane potential. To characterize the activated ion channels, the variations of the intracellular calcium (Ca(2+)) concentration were explored using a fluorescent marker. The results revealed that ultrasound stimulation induces a rapid hyperpolarization of cell membrane potential when the microbubble is in direct contact with the cell, but the potential returned to its initial value when ultrasound stimulation stopped. The change in cell membrane potential indicates the activation of specific ion channels and depends on the quality of microbubble adhesion to the cell membrane. Microbubbles were shown to induce a mechanical stretch activating BKca channels. Simultaneous Ca(2+) measurements indicate a slow and progressive Ca(2+) increase that is likely a consequence of BKca channels opening not a cause. These results demonstrate that microbubbles' oscillations under ultrasound activation entail modulation of cellular function and signaling by t- riggering the modulation of ionic transports through the cell membrane. Cells response to the mechanical stretch caused by gentle microbubble oscillations is characterized by the opening of BKca stretch channels and a Ca(2+) flux, which might potentially trigger other cellular responses responsible for membrane sonopermeabilization.