Targeting ribosome biogenesis reinforces ERK-dependent senescence in pancreatic cancer.

Pancreatic adenocarcinomas (PDAC) often possess mutations in K-Ras that stimulate the ERK pathway. Aberrantly high ERK activation triggers oncogene-induced senescence, which halts tumor progression. Here we report that low-grade pancreatic intraepithelial neoplasia displays very high levels of phospho-ERK consistent with a senescence response. However, advanced lesions that have circumvented the senescence barrier exhibit lower phospho-ERK levels. Restoring ERK hyperactivation in PDAC using activated RAF leads to ERK-dependent growth arrest with senescence biomarkers. ERK-dependent senescence in PDAC was characterized by a nucleolar stress response including a selective depletion of nucleolar phosphoproteins and intranucleolar foci containing RNA polymerase I designated as senescence-associated nucleolar foci (SANF). Accordingly, combining ribosome biogenesis inhibitors with ERK hyperactivation reinforced the senescence response in PDAC cells. Notably, comparable mechanisms were observed upon treatment with the platinum-based chemotherapy regimen FOLFIRINOX, currently a first-line treatment option for PDAC. We thus suggest that drugs targeting ribosome biogenesis can improve the senescence anticancer response in pancreatic cancer.

Design, synthesis, and characterization of novel aminoalcohol quinolines with strong in vitro antimalarial activity.

Malaria is the fifth most lethal parasitic infections in the world. Herein, five new series of aminoalcohol quinolines including fifty-two compounds were designed, synthesized and evaluated in vitro against Pf3D7 and PfW2 strains. Among them, fourteen displayed IC50 values below or near of 50.0 nM whatever the strain with selectivity index often superior to 100.17b was found as a promising antimalarial candidate with IC50 values of 14.9 nM and 11.0 nM against respectively Pf3D7 and PfW2 and a selectivity index higher than 770 whatever the cell line is. Further experiments were achieved to confirm the safety and to establish the preliminary ADMET profile of compound 17b before the in vivo study performed on a mouse model of P. berghei ANKA infection. The overall data of this study allowed to establish new structure-activity relationships and the development of novel agents with improved pharmacokinetic properties.

Loss of brain inter-frequency hubs in Alzheimer's disease.

Alzheimer's disease (AD) causes alterations of brain network structure and function. The latter consists of connectivity changes between oscillatory processes at different frequency channels. We proposed a multi-layer network approach to analyze multiple-frequency brain networks inferred from magnetoencephalographic recordings during resting-states in AD subjects and age-matched controls. Main results showed that brain networks tend to facilitate information propagation across different frequencies, as measured by the multi-participation coefficient (MPC). However, regional connectivity in AD subjects was abnormally distributed across frequency bands as compared to controls, causing significant decreases of MPC. This effect was mainly localized in association areas and in the cingulate cortex, which acted, in the healthy group, as a true inter-frequency hub. MPC values significantly correlated with memory impairment of AD subjects, as measured by the total recall score. Most predictive regions belonged to components of the default-mode network that are typically affected by atrophy, metabolism disruption and amyloid-ß deposition. We evaluated the diagnostic power of the MPC and we showed that it led to increased classification accuracy (78.39%) and sensitivity (91.11%). These findings shed new light on the brain functional alterations underlying AD and provide analytical tools for identifying multi-frequency neural mechanisms of brain diseases.

[Schooling and care of mild intellectual disability children]. / Parcours scolaire et prise en charge médico-éducative des enfants avec déficience intellectuelle légère.

Studies on mild intellectual disability (MID) are scarce. The aim of this study was to describe the educational and medical care trajectories and their determinants in children with MID. The study population concerned children born in 1997 and resident in a French county (Isère) in 2008. MID was defined as an overall IQ score between 50 and 69. For the present study, this definition was adjusted by integrating the IQ confidence intervals so that the risk of IQ measurement relativity and possible score discrepancy could be taken into account. Of the 267 children included, 180 (67%) were identified through an institute that decides upon special education and allowances (MDPH) and 87 (33%) through the educational system. The parents of 181 children (68%) accepted to answer a telephone questionnaire, describing their child's educational and medical history. Children with MID frequently presented clinical signs and comorbidities. Educational trajectories were quite varied: a majority of the children (52.9%) were oriented toward sections with adapted general and professional education (SEGPA) after finishing primary school, a minority (41.3%) were oriented towards specialized schools, such as medical-educational institutions, and a small proportion of children (5.8%) stayed in ordinary school. Children followed the SEGPA orientation more frequently when a relative written language disorder was present, and autism-spectrum disorders or other clinical signs were absent. Concerning follow-up care and rehabilitation, children mostly took part in speech therapy (76.2%) and psychotherapy (55.8%). The French law dating from 2005, ensuring equal opportunity for people with disabilities, has borne fruit in the diversification of educational trajectories.

[Place and role of safety pharmacology in drug development]. / Place et rôle de la pharmacologie de sécurité dans le développement des médicaments.

SUMMARY: Safety pharmacology is a key regulatory step for drug development and approval. Prior to phase I, the effects of a drug candidate should be evaluated and characterized on vital functions (cardiovascular, respiratory and central nervous system) according to good laboratory practice standards. For cardiovascular evaluation, effects on blood pressure and electrocardiogram should be explored with a particular emphasis on ventricular repolarization prolongation, a major risk factor for life-threatening arrhythmias, like "torsades de pointe". Global behaviour, motor activity, reflexes and body temperature should be evaluated in animals. A dedicated study is necessary for respiratory function evaluation. All of these studies should be conducted after single administration of the compound administered by the anticipated clinical route. Dependence potential and abuse liability should be characterized for innovative drugs and/or drugs acting on the central nervous system. Evidence for adverse effects at discovery stage with high throughput systems is becoming a key step of decision-making process for pharmaceutical industry. Therefore, determination of the safety margin, risk/benefit ratio analysis and investigation of adverse effects are major decisional elements for providing safety reassurance to patients. Safety of patients will also be improved through modelling methodologies allowing a safer transposition of experimental pharmacology results to clinical pharmacology.

Modeling thermal influence on animal growth and sex determination in reptiles: being closer to the target gives new views.

Many species of oviparous reptiles, including crocodilians, a majority of turtles, some lizards and the 2 closely related species of Sphenodon have been shown to display temperature-dependent sex determination (TSD). Whereas it has been demonstrated very early that TSD also occurs in natural conditions, the relationship between a time series of changing temperatures and sex ratio remains a challenging problem for reptiles. We describe how a physiological model of embryo growth, gonadal development and aromatase activity can produce outputs that mimic well TSD. We provide an enhancement of a previously published model taking into account direct effect of temperature on aromatase activity. The comparison between the original model and the new one suggests that aromatase expression is controlled by a repressor factor expressed at masculinizing temperatures rather than its enhancement at feminizing temperatures.

Evolution of habitat-dependent sex allocation in plants: superficially similar to, but intrinsically different from animals.

Because pollen disperses and ovules do not, a basic difference in dispersal abilities of male and female gametes exists in plants. With an analytical model, we show that the combination of such sex-biased dispersal of gametes and variation of habitat quality results in two opposite selective forces acting on the evolution of sex allocation in plants: (i) a plant should overproduce pollen in good patches and overproduce ovules in poor patches in order to equilibrate secondary sex ratios of gametes after pollen dispersal; (ii) a plant should overproduce ovules in good patches and overproduce pollen in poor patches in order to increase the likelihood that its progeny establishes in good patches. Our theoretical results indicate that the evolution of habitat-dependent sex allocation should be favoured in plants, in a direction that depends on the relative dispersal ability of pollen and seeds. We also show that superficially similar predictions obtained for habitat-dependent evolutionarily stable sex allocation in animals actually result from a completely different balance between the two underlying evolutionary forces.

Synthesis and preliminary behavioural evaluation in mice of new 3-aryl-3-pyrrol-1-ylpropanamides, analogues of FGIN-1-27 and FGIN-1-43.

The 2-aryl-3-indoleacetamides FGIN-1-27 and FGIN-1-43 have already been characterized in-vitro as potent and specific ligands for the mitochondrial DBI receptor. This affinity was associated with psychotropic properties in several rodent behavioural tasks (in particular anxiolytic action) via enhancement of GABA transmission through neurosteroid production. The synthesis of new 3-aryl-3-pyrrol-1-ylpropanamides 1a-i, analogues of FGIN-1-27 and FGIN-1-43, is described in four steps starting from the corresponding arylaldehydes. Preliminary evaluation of these compounds in behavioural studies (spontaneous locomotor activity and anxiolytic activity) in mice was also undertaken.

Synthesis of cone, partial-cone, and 1,3-alternate 25, 27-Bis

The preparation of 25,27-bis[1-(2-ethyl)hexyl]- and 25, 27-bis[1-(2-tert-butoxy)ethyl]calix[4]arene-crown-6 combining one polyether crown-6 and one alkylchain O-attached on each side of a calix[4]arene in the cone, partial-cone, and 1,3-alternate conformations are reported. The control over 25, 27-bisalkylcalix[4]arene-crown-6 conformation via varying specific reaction conditions was studied. The series of calix[4]arenes have been prepared by two routes, which differ in the order in which the alkyl or polyether groups were introduced. Moreover, methods have been developed to selectively prepare the cone and partial-cone conformers by using an appropriate base in the alkylation reactions. The conformations of these new derivatives have been probed by (1)H NMR analysis and X-ray crystallography. The (1)H and (13)C NMR spectra of 25,27-bis[1-(2-ethyl)hexyl]calix[4]arene-crown-6, 1, 3-alternate 1, cone 2, and partial-cone 3 are also discussed.

New aromatase inhibitors. Synthesis and biological activity of aryl-substituted pyrrolizine and indolizine derivatives.

We report herein the design and the synthesis of some aryl-substituted pyrrolizine and indolizine derivatives, on the basis of a hypothetical pharmacophore structure designed to fit the catalytic site of the human cytochrome P450 aromatase. The in vitro biological evaluation of these compounds allowed us to point out two new potent non-steroidal aromatase inhibitors, MR 20494 and MR 20492, with IC50 values in the range of 0.1 microM.

Maternal inheritance of chloroplasts in the horsetail Equisetum variegatum (Schleich.).

Reliable data concerning the transmission of chloroplasts in the Pteridophyta are needed both for phylogenies based on chloroplast DNA (cpDNA) sequences and in order to study the evolution of this trait in conjunction with the evolution of the life cycle and the sexual reproduction of land plants. For the first time, this paper describes organelle transmission in the division Sphenophyta, represented by the extant genus Equisetum. By following the fate of polymorphic cpDNA during three intraspecific reciprocal crosses we found no trace of paternal transmission in Equisetum variegatum. The seemingly strict maternal transmission of cpDNA in this species suggests that uniparental chloroplast inheritance preceded the evolution of heterospory in the seed-plant lineage.

Synthesis of new 2-(aminomethyl)-4-phenylpyrrolo[1,2-a]-quinoxalines and their preliminary in-vivo central dopamine antagonist activity evaluation in mice.

In the search for antipsychotic agents that are not associated with extrapyramidal side effects, efforts have been focused on finding selective D4-receptor antagonists and investigating their pharmacology. Our laboratory has developed a synthesis program for new pyrroloquinoxalines with therapeutic potential. We have described the synthesis of some new pyrroloquinoxalines with substituted arylpiperazino or aryltetrahydropyrido chain at position 3 of the quinoxaline ring (2-(4-phenylpiperazin-1-ylmethyl)-4-phenylpyrrolo[1,2-a]quinoxalinium oxalate (3a), 2-[4-(2-methoxyphenyl)piperazin-1-ylmethyl]-4-phenylpyrrolo[1,2-a]quinoxalinium oxalate (3b), 2-[4-(3-trifluoromethylphenyl)piperazin-1-ylmethyl]-4-phenylpyrrolo[1,2-a]quinoxalinium oxalate (3c), 2-[4-(4-chlorophenyl)piperazin-1-ylmethyl]-4-phenylpyrrolo[1,2-a]quinoxalinium oxalate (3d), 2-(4-pyridin-2-ylpiperazin-1-ylmethyl)-4-phenylpyrrolo[1,2-a]quinoxalinium oxalate (3e), and 2-(4-phenyl1,2,3,6-tetrahydropyridin-1-ylmethyl)-4-phenylpyrrolo[1,2-a]quinoxalinium oxalate (3f)). A preliminary pharmacological study of these products was conducted using climbing behaviour induced by apomorphine (2.5 mg kg(-1), s.c.) in mice. The derivatives were administered intraperitoneally 30 min before apomorphine. Haloperidol, chlorpromazine and clozapine were used as references. Among this series, 3b, 3c and 3f revealed a central dopamine antagonist activity. The most active derivative was 3b, which exhibited a profile relatively close to clozapine.

Drugs that prolong QT interval as an unwanted effect: assessing their likelihood of inducing hazardous cardiac dysrhythmias.

Medicinal products that, as an unwanted effect, prolong the QT interval of the electrocardiogram (ECG) can trigger episodes of polymorphic ventricular dysrhythmias, called torsades de pointes, which occasionally culminate in sudden death. The accurate measurement of QT interval requires the adoption of appropriate criteria of recording, measurement and data processing. Traditionally, QT interval is standardised to a reference heart rate of 60 beats/min by using the Bazett algorithm. However, this correction method can bias observed QT intervals in either direction. The ECG reflects cardiac electrical currents generated by ions (Na+, K+ and Ca2+) entering and leaving the cytosol mainly via transmembrane channels. Na+ and Ca2+ carry inward depolarising currents (INa, ICa) whereas K+ carries outward repolarising currents (Ito, IKr, IKS and IK1). Sometimes, a prolonged QT interval is a desired drug effect but, more commonly it is not, and reflects abnormalities in cardiac repolarisation heralding torsades de pointes. Furthermore, the potential torsadogenic activity of drugs is favoured by concurrent cardiac risk factors (old age, female gender, bradycardia, electrolyte imbalances, cardiac diseases etc.) which reduce cardiac repolarisation reserve. The evaluation of the cardiac safety of drug candidates can be started by determining their potency as IKr blockers in cloned Human Ether-a-go-go Related Gene (HERG) channels expressed in mammalian cells. Compounds passing successfully this test (desirable cardiac safety index > 30, calculated as ratio of IC50 against IKr over ED50 determined in an efficacy test) should be further investigated in other relevant human cardiac ion currents, in in vitro animal heart preparations and finally in in vivo pharmacodynamic models. The decision as to whether the potential benefit of a new drug outweighs the cardiac risk inherent in its therapeutic use should be made in the light of the condition that it is expected to treat and with reference to alternative drug therapies. If a drug represents a unique therapeutic advance, non-clinical and clinical signals of unsatisfactory cardiac safety may not constitute sufficient grounds to abandon its development. However, if the drug offers only marginal benefits over existing therapies, decisions concerning its possible development should be taken by corporate policy makers.

Preclinical in vitro cardiac electrophysiology: a method of predicting arrhythmogenic potential of antihistamines in humans?

The cardiac action potential results from a dynamic balance between inward depolarising Na+ and Ca2+ currents and outward K+ repolarising currents. During a cardiac cycle, the resultant of repolarisation phase from all ventricular cells is represented by the QT interval of the surface ECG. Congenital long QT syndrome (LQTS) is characterised by polymorphic ventricular tachycardia sometimes with twisting QRS morphology (torsade de pointes) which, although usually self-limiting, can result in sudden cardiac death. Acquired LQTS can be induced by a variety of drugs, including some nonsedative histamine H1 receptor antagonists (astemizole, terfenadine). The Committee for Proprietary Medicinal Products of the European Union has recently proposed studying the action potential in in vitro heart preparations as a preclinical test for predicting the propensity of noncardiovascular drugs to induce malignant QT prolongation in humans. The effects of several histamine H1 receptor antagonists on the electrically evoked action potential have been evaluated in rabbit Purkinje fibres. In this preparation, astemizole (0.3 to 10 micromol/L) prolongs the duration of the action potential measured at the level where repolarisation is 90% complete (APD90). This effect is dependent on drug concentration, incubation time, pacing frequency and K+ or Mg2+ concentration. Astemizole also markedly depresses the rate of rise of the action potential (Vmax). Terfenadine showed qualitatively similar, but quantitatively smaller, effects in this model. The histamine H1 receptor antagonists cetirizine, ebastine, carebastine, loratadine and fexofenadine do not significantly affect APD90 at 1 micromol/L, but cetirizine and carebastine prolong it slightly at 10 micromol/L. In conclusion, in rabbit Purkinje fibres, astemizole and terfenadine produce adverse electrophysiological effects at concentrations which may be achieved in the human myocardium in certain clinical situations. APD90 lengthening induced by carebastine and cetirizine is minor and occurs at concentrations that are very unlikely to be encountered clinically, since these drugs, in contrast to astemizole and terfenadine, do not accumulate in the myocardium. Direct extrapolation of preclinical results to humans requires great caution, since malignant QT prolongations by terfenadine and astemizole are extremely rare clinical events. However, since prolongation of the QT interval often precedes the development of torsade de pointes, any significant delay in cardiac repolarisation produced by noncardiovascular drugs in preclinical, and particularly in clinical, studies should, in general, be considered to indicate a potential cardiac risk in humans. Its significance should subsequently be evaluated in appropriate studies in patients with conditions known to predispose to arrhythmias.

MR 20492 and MR 20494: two indolizinone derivatives that strongly inhibit human aromatase.

In this study, we describe the synthesis of a new family of indolizinone derivatives designed to fit an extrahydrophobic pocket within the active site of aromatase and to strongly inhibit human aromatase. This could help improve the specificity of the inhibitors. Equine aromatase, very well characterized biochemically, is used as a comparative model. Indeed, in a previous comparison between both human and equine aromatases, we described the importance of the interaction between the inhibitor and this pocket for the indane derivative MR 20814. MR 20492 and MR 20494 are more potent inhibitors of human aromatase (Ki/Km: 1.0+/-0.3 and 0.5+/-0.3, respectively). The Ki/Km for MR 20494 is slightly higher than that obtained for fadrozole (0.1+/-0.0) and Ki/Km for both indolizinone derivatives are lower than those obtained for 4-hydroxyandrostenedione (1.9+/-0.8) and MR 20814 (8.1+/-.7). These new compounds are not enzyme inactivators. Moreover, as indicated by the higher Ki/Km values obtained with equine enzyme (9.0+/-0.6 and 6.1+/-1.6 for MR 20492 and MR 20494, respectively), both human and equine aromatase active sites appear to be structurally different. Difference absorption spectra study (350-500 nm) revealed that MR20492 and MR20494 were characterized by a combination of type-I and -II spectra with both enzymes. This result could be due to the isomerization of the molecule in polar solvent (Z and E forms). The evaluation of these new molecules, as well as 4-hydroxyandrostenedione and fadrozole, on aromatase activity in transfected 293 cell cultures evidenced a strong inhibition (IC50: 0.20+/-0.03 microM, 0.20+/-0.02 microM and 0.50+/-0.40 microM for MR 20494, fadrozole and 4-OHA, respectively) except for MR 20492 (3.9+/-0.9 microM) and MR 20814 (10.5+/-0.6 microM). These results proved that these molecules formed part of a promising family of potent inhibitors and that they penetrate 293 cells, without evidencing any cytotoxicity in Hela cells with MTT assay. This is thus encouraging for the development of new drugs for the treatment of estrogen-dependent cancers, these molecules also constitute new tools for understanding the aromatase active site.

Synthesis and evaluation of the CNS activity of new 4-alkoxyphenylimidazolidin-2-ones.

Various 4-alkoxyphenylimidazolidin-2-ones were prepared from benzaldehydes via a Curtius rearrangement and were evaluated for their anticonvulsant activities.