Mechanisms of depolymerization and activation of a polysialic acid and its tetramer by hydrogen peroxide.

Naturally occurring polysialic acid (PSA), appropriately functionalized, has been widely used in different biological products. The present paper describes an original approach which enables to both activate and depolymerize the PSA, by reacting with hydrogen peroxide. In order to understand the mechanisms, we investigate the course of H2O2 reactions with the native PSA and with a simpler model, the tetrasialic acid (4SA). Three recurrent reactions were observed. First, we detected a very fast and irreversible decarbonylation at the reducing end of the polysaccharide. Then, the hydroxyl radicals (generated via the Fenton reaction) were responsible for the depolymerization of glycosidic linkages by substitution reactions. Finally, the oxidation of hydroxyl groups led to the formation of carbonyl groups and the carbohydrate's activation.

Oxidation of sialic acid using hydrogen peroxide as a new method to tune the reducing activity.

Functionalized sialic acids are useful intermediates to prepare a wide range of biological products. As they often occur at a non-reducing terminal of oligosaccharides, the most used technique to activate them is by periodate-mediated oxidation of their glycerol side chain. Here, we describe an alternative, non toxic, and environmentally-friendly method to activate the sialic acid residues by hydrogen peroxide oxidation. Four oxidative systems involving H2O2, EDTA, iron chloride, and UV light were studied and the products obtained were analyzed by LC-MS and NMR, before and after a derivatization reaction. At first, we observed, for each system, an irreversible decarbonylation reaction at the reducing end. Then, the decarbonylated sialic acid (DSA) was oxidized and fragmented into a mix of carbonyls and carboxyl acids, more or less fast according to the experimental conditions. Analysis of the reaction indicated an apparent radical mechanism and heterolytic alpha-hydroxy-hydroperoxide cleavages. The modest reducing activity was mainly explained as a consequence of over-oxidation reactions.

A 3D-QSAR CoMSIA study on 3-azolylmethylindoles as anti-leishmanial agents.

A three-dimensional quantitative structure-activity relationship (3D-QSAR) study using Comparative Molecular Similarity Indices Analysis (CoMSIA) was conducted on a series of 3-azolylmethylindoles as anti-leishmanial agents. Evaluation of 24 compounds synthesized in our laboratory served to establish the model. A random search was performed on the library of compounds, and molecules of the training set were aligned on common elements of template molecule 13, one of the most active compounds. The best predictions were obtained from multifit procedure with a CoMSIA model combining steric, electrostatic, hydrophobic and hydrogen bond acceptor fields (q2 = 0.594, r2 = 0.897). The model was validated using an external test set of 7 compounds giving a satisfactory predictive r2 value of 0.649. Information obtained from CoMSIA contour maps could be used for further design of more promising inhibitors.

Qualitative analysis of the relation between DNA microarray data and behavioral models of regulation networks.

We introduce a mathematical framework that allows to test the compatibility between differential data and knowledge on genetic and metabolic interactions. Within this framework, a behavioral model is represented by a labeled oriented interaction graph; its predictions can be compared to experimental data. The comparison is qualitative and relies on a system of linear qualitative equations derived from the interaction graph. We show how to partially solve the qualitative system, how to identify incompatibilities between the model and the data, and how to detect competitions in the biological processes that are modeled. This approach can be used for the analysis of transcriptomic, metabolic or proteomic data.

Potential application of plant lipid transfer proteins for drug delivery.

Ligand-binding proteins show an increasing interest as drug carriers and delivery systems [Wolf FA, Brett GM. Pharmacol Rev, 1000;52:207-36]. The wide binding properties of plant non-specific lipid transfer proteins such as LTP1 also offer many unexplored possibilities for such a task. In the present paper, by using intrinsic tyrosine LTP1 fluorescence, we survey, for the first time, the binding of wheat LTP1 with various ligands having cosmetic or pharmaceutical applications. LTP1 was found to bind skin lipids such as sphingosine, sphingomyelin, and cerebroside with an affinity of about one micromolar, low enough to allow a slow release of these molecules. Ether phospholipids and an azole derivative BD56 having antitumoral and/or antileishmania properties were also shown to bind LTP1 with similar affinity. Finally, amphotericin B, which is widely used as an antifungal drug, was shown to form a complex with LTP1, although no affinity could be determined. This binding study is a prerequisite for further work aimed at developing applications in LTP-mediated transport and controlled release of low molecular weight drugs.

[Psychiatric manifestations of a new variant of Creutzfeldt-Jakob disease. Apropos of a case]. / Manifestations psychiatriques du nouveau variant de la maladie de Creutzfeldt-Jakob. A propos d'un cas.

UNLABELLED: The new variant of Creutzfeldt-Jakob disease (nvCJD) was first described in the UK in 1996 (16). The nvCJD differs from sporadic, genetic and iatrogenic CJD. Creutzfeldt-Jakob disease is closely associated with an abnormal isoform PrPSc of a cell-surface glycoprotein, prion protein (14). Molecular analysis suggests that nvCJD is caused by the same prion strain as bovine spongiform encephalopathy (BSE) (4, 10). To the end of September 2000, there have been 82 cases of nvCJD in the UK. We report the second French case of nvCJD to our knowledge (5, 13). CASE REPORT: This 36 year old woman was referred by a local general practitioner with a 6 month history of psychiatric symptoms of major depressive disorder. According to her family, the patient had suffered from personality change for several months before the onset of depression including apathy, emotional lability, infantile affect. There was no history of health problems. As she was admitted to the psychiatric department of our hospital in Paris suburbs, she presented a major depressive disorder. There were no specific psychiatric features allowing distinction from common depressive disorders, except a marked emotional lability. The patient's condition progressed rapidly within the following days. She presented memory impairment and disorientation. Drug treatments, clomipramine (125 mg/day) and venlafaxine (200 mg/day), were used with no benefit. She presented subsequently transient delusions and auditory hallucinations, fleeting for some hours. The predominant delusional themes were somatic type and pregnancy. The delusions were concomitant with delusions of the onset of cognitive impairment. The patient tested negative for the P 14.3.3 protein in the CSF. Computed tomography scan of the brain did not show any relevant abnormality. The electroencephalogram showed non specific slow wave activity. The neurological symptoms developed 7 months after the onset of depressive symptoms including ataxia, myoclonus, excessive daytime drowsiness, headache. After the onset of neurological symptoms, the illness progressed rapidly over the next 2 months with cognitive impairment, particularly memory impairment, myoclonus, ataxia, incontinence of urine and progressive immobility leading to dependency. CSF tests were negative. She was referred to a neurology department where the diagnosis was confirmed by brain biopsy (detailed elsewhere). The patient died in a state of akinetic mutism. DISCUSSION: The clinical features of our patient were consistent with previous descriptions of nvCJD, mainly those of the National CJD Surveillance Unit studies (17): early psychiatric symptoms, prolonged duration of illness (median: 14 months), earlier age at death, compared with sporadic CJD. Psychiatric symptoms occur in the clinical course in about a third of cases of sporadic CJD (3). In contrast, of the 35 cases that have died of nvCJD identified in the study by Will et al. (17), 34 suffered from early and prominent psychiatric symptoms, mainly depression and anxiety. In most of the patients, the first symptoms were psychiatric. Drug treatment was used in most cases, some patients had a transient improvement (18). The patient without psychiatric symptoms reported by the NCJDSU (17) was emotionally labile. Infantile affect and emotional lability, found in our patient, are frequently reported in other studies (1, 18). Schizophreniform disorders have been described during the clinical course, with auditory and visual hallucinations and paranoid delusions (17, 18). The insomnia and excessive daytime drowsiness our patient presented have been described in similar cases (18). Investigations are important to rule out alternative diagnoses. EEG records do not show periodic triphasic complexes as in sporadic CJD. The P 14.3.3 protein in the CSF is positive in half the cases of nvCJD (17). First neurological symptoms developed 6 months after the onset of psychiatric symptoms including ataxia, myoclonus and persistent painful sensory symptoms (17, 18). In most of the cases, MRI brain scans show bilateral pulvinar high signal (17), found subsequently in our patient and detailed elsewhere (13). The terminal stages are progressive cognitive impairment, helplessness and akinetic mutism. CONCLUSION: The first symptoms of this patient were purely psychiatric and difficult to distinguish from common psychiatric disorders. Clinical surveillance of human prion disease is crucial in France, as in UK. The link with BSE has dramatically highlighted the need for neurological and neuropsychological precise investigations.

Is substance abuse in schizophrenia related to impulsivity, sensation seeking, or anhedonia?

OBJECTIVE: The authors compared impulsivity, sensation seeking, and anhedonia in a group of schizophrenic patients with and without lifetime substance abuse or dependence. METHOD: Patients (N=100) with schizophrenia or schizoaffective disorder (per DSM-III-R criteria) were assessed with the Composite International Diagnostic Interview's section on psychoactive substance use disorder, the Positive and Negative Syndrome Scale, the Barratt Impulsivity Scale, the Zuckerman Seeking Sensation Scale, and the Chapman Physical Anhedonia Scale. RESULTS: The mean scores for impulsivity and sensation seeking were higher in the group with substance abuse (N=41) than in the group without substance abuse (N=59). No significant difference between groups was found regarding physical anhedonia. CONCLUSIONS: As in the general population, high levels of impulsivity and sensation seeking are associated with substance abuse in patients with schizophrenia.

[Synthesis and biological evaluation of indole derivatives acting as anti-inflammatory or antitumoral drugs]. / Dérivés indoliques à activités anti-inflammatoire ou antitumorale.

Two axes of research have been explored, one about promising non-acidic non-steroidal anti-inflammatory derivatives, with indolin-2-one as structural core and another one about aromatase inhibitors, characterized by azolylmethyl or alpha-azolylbenzyl chain on indole nucleus. Knoevenagel reaction led to indolin-2-ones substituted by either 2,6-di-tert-butylphenol chain or 1, 4-dihydropyridine chain, revealing antioxydant or anti-inflammatory activities. Aromatase is a logical target in the treatment of hormono-dependent breast cancer in postmenopausal women. Among non steroidal inhibitors of this enzyme, diverse compounds with anilino or azaheterocyclic moiety are currently used or undergoing clinical trials. Our pharmacomodulation in azolylmethylindole or alpha-azolylbenzylindole series led to compounds with high level aromatase inhibitory activity. Work to determine their selectivity by measuring their inhibitory effect on P450 17alpha enzyme was also carried out. A first molecular modeling approach with Discover software was performed to evaluate interactions between our molecules and the catalytic site of P450cam.

New selective nonsteroidal aromatase inhibitors: synthesis and inhibitory activity of 2,3 or 5-(alpha-azolylbenzyl)-1H-indoles.

Six azolyl substituted indoles were synthesized and tested for their activity to inhibit two P450 enzymes: P450 arom and P450 17a. It was observed that the introduction of alpha-imidazolylbenzyl chain at carbon 3 or 5 on indole nucleus led to very active molecules. Compounds 22, 23 and especially 33 demonstrate very high potential against P450 arom. Under our assay conditions of high substrate concentration the IC50 are 0.057, 0.0785 and 0.041 microM, respectively. These compounds are moderate inhibitors against P450 17alpha.

Synthesis and in vitro evaluation of 3-(1-azolylmethyl)-1H-indoles and 3-(1-azolyl-1-phenylmethyl)-1H-indoles as inhibitors of P450 arom.

In the challenge to develop potent inhibitors of aromatase for reducing the levels of estrogens, we found that azolyl-substituted indoles inhibit aromatase activity, 3-(1-Azolylmethyl)-1H-indoles 9-15 and 3-(1-azolyl-1-phenylmethyl)-1H-indoles 22-25 were prepared, and tested on their ability to inhibit P450 arom. Analysis of the inhibitory effect exerted by several derivatives (11, 12, 22, and 23) on microsomal aromatase in vitro activity indicates that azolyl-substituted indoles containing an imidazole moiety are more potent inhibitors than triazole derivatives. In the first series, the introduction of the N-benzyl moiety has been found to enhance the inhibitory profile of these 3-(1-azolylmethyl)-1H-indole derivatives. The corresponding 4-fluoro derivative 12 displays the highest inhibitory activity (IC50 = 0.0718 microM) of all investigated compounds; thus, 12 is 258 times as potent as aminoglutethimide (AG). The presence of a chloro grouping in para position of the phenyl ring in compounds 22 and 24 exerts a positive effect only in the triazol-l-yl sub-series: compound 25 is 4-fold more potent than 24.

[Urination disorders in multiple sclerosis: value of urodynamic assessment]. / Les troubles urinaires dans la sclérose en plaques: intérêt du bilan urodynamique.

Urinary troubles are common in patients with multiple sclerosis. The management of these troubles requires an accurate analysis. Urodynamic assessment was preformed in 117 patients with urinary symptoms positively diagnosed as suffering from multiple sclerosis. Urinary symptoms are not always correlated to urodynamic patterns. We have studied the correlation between urinary symptoms and urodynamic findings. Urodynamic results are similar to most of previous series: detrusor hyperreflexia is the most frequent abnormality, detrusor sphincter dyssynergia is diagnosed in 50% of the patients. There is some correlations with symptoms, but there are insufficient for an accurate diagnosis. Postvoid residue for urinary tracts infectious diseases, and sphincter incompetence for urinary incontinence are the main risk factors.