Antibacterial Activity of combinatorial treatments composed of transition-metal/antibiotics against Mycobacterium tuberculosis.

Notwithstanding evidence that tuberculosis (TB) is declining, one of the greatest concerns to public health is the emergence and spread of multi-drug resistant strains of Mycobacterium tuberculosis (MDR-TB). MDR-TB are defined as strains which are resistant to at least isoniazid (INH) and rifampicin, the two most potent TB drugs, and their increasing incidence is a serious concern. Recently, notable efforts have been spent on research to pursue novel treatments against MDR-TB, especially on synergistic drug combinations as they have the potential to improve TB treatment. Our research group has previously reported promising synergistic antimicrobial effects between transition-metal compounds and antibiotics in Gram-negative and Gram-positive bacteria. In this work, we evaluated antimycobacterial activity of transition-metals/antibiotics combinatorial treatments against first-line drug resistant strains of Mycobacterium tuberculosis. Our data showed that INH/AgNO3 combinatorial treatment had an additive effect (bactericidal activity) in an isoniazid-resistant clinical strain of Mycobacterium tuberculosis. Moreover, in vitro evaluation of cytotoxicity induced by both, the individual tratments of AgNO3 and INH and the combinatorial treatment of INH/AgNO3 in murine RAW 264.7 macrophages and human A549 lung cells; showed no toxic effects. Together, this data suggests that the INH/AgNO3 combinatorial treatment could be used in the development of new strategies to treat resistant strains of Mycobacterium tuberculosis.

Regulation of eIF4F Translation Initiation Complex by the Peptidyl Prolyl Isomerase FKBP7 in Taxane-resistant Prostate Cancer.

PURPOSE: Targeted therapies that use the signaling pathways involved in prostate cancer are required to overcome chemoresistance and improve treatment outcomes for men. Molecular chaperones play a key role in the regulation of protein homeostasis and are potential targets for overcoming chemoresistance.Experimental Design: We established 4 chemoresistant prostate cancer cell lines and used image-based high-content siRNA functional screening, based on gene-expression signature, to explore mechanisms of chemoresistance and identify new potential targets with potential roles in taxane resistance. The functional role of a new target was assessed by in vitro and in vivo silencing, and mass spectrometry analysis was used to identify its downstream effectors. RESULTS: We identified FKBP7, a prolyl-peptidyl isomerase overexpressed in docetaxel-resistant and in cabazitaxel-resistant prostate cancer cells. This is the first study to characterize the function of human FKBP7 and explore its role in cancer. We discovered that FKBP7 was upregulated in human prostate cancers and its expression correlated with the recurrence observed in patients receiving docetaxel. FKBP7 silencing showed that FKBP7 is required to maintain the growth of chemoresistant cell lines and chemoresistant tumors in mice. Mass spectrometry analysis revealed that FKBP7 interacts with eIF4G, a component of the eIF4F translation initiation complex, to mediate the survival of chemoresistant cells. Using small-molecule inhibitors of eIF4A, the RNA helicase component of eIF4F, we were able to kill docetaxel- and cabazitaxel-resistant cells. CONCLUSIONS: Targeting FKBP7 or the eIF4G-containing eIF4F translation initiation complex could be novel therapeutic strategies to eradicate taxane-resistant prostate cancer cells.

Computer-aided diagnosis system: a Bayesian hybrid classification method.

A novel method to classify multi-class biomedical objects is presented. The method is based on a hybrid approach which combines pairwise comparison, Bayesian regression and the k-nearest neighbor technique. It can be applied in a fully automatic way or in a relevance feedback framework. In the latter case, the information obtained from both an expert and the automatic classification is iteratively used to improve the results until a certain accuracy level is achieved, then, the learning process is finished and new classifications can be automatically performed. The method has been applied in two biomedical contexts by following the same cross-validation schemes as in the original studies. The first one refers to cancer diagnosis, leading to an accuracy of 77.35% versus 66.37%, originally obtained. The second one considers the diagnosis of pathologies of the vertebral column. The original method achieves accuracies ranging from 76.5% to 96.7%, and from 82.3% to 97.1% in two different cross-validation schemes. Even with no supervision, the proposed method reaches 96.71% and 97.32% in these two cases. By using a supervised framework the achieved accuracy is 97.74%. Furthermore, all abnormal cases were correctly classified.

Evaluation of 13 selected medicinal plants from Burkina Faso for their antiplasmodial properties.

AIM OF THE STUDY: The aim of this study was to evaluate the antiplasmodial properties of 13 plants used against malaria in traditional medicine in Burkina Faso. MATERIALS AND METHODS: In vitro antiplasmodial activity of dichloromethane, methanol and aqueous crude extracts obtained from vegetal samples collected in Burkina Faso was first evaluated on the Plasmodium falciparum 3D7 chloroquine-sensitive strain using a colorimetric method. RESULTS: Thirteen extracts obtained from 8 different species were found to exhibit antiplasmodial activity (IC(50)<50 microg/ml). Five species demonstrated a moderate activity (15 microg/ml

A molecular dynamics study of an archaeal tetraether lipid membrane: comparison with a dipalmitoylphosphatidylcholine lipid bilayer.

Molecular dynamics simulations of an archaeal membrane made up of bipolar tetraether lipids and a dipalmitoylphosphatidylcholine (DPPC) lipid membrane were performed and compared for the first time. The simulated archaeal membrane consists of a pure monolayer of asymmetrical lipids, analogous to the main polar lipid [MPL; Swain, M., Brisson, J.-R., Sprott, G.D., Cooper, F.P., and Patel, G.B., (1997) Identification of beta-L-Gulose as the Sugar Moiety of the Main Polar Lipid of Thermoplasma acidophilum, Biochim. Biophys. Acta 1345, 56-64] found in T. acidophilum, an extremophile archaeal organism. This simulated membrane lipid contains two cyclopentane rings located on one of the two aliphatic chains of the lipid. The archaeal membrane is simulated at 62degreesC, slightly above the optimal growth temperature of T. acidophilum. We compared the organization of this tetraether lipid monolayer with a DPPC bilayer simulated at 50degreesC, both of them being modeled in a partially hydrated state. Our results assess the singularity of the tetraether lipid organization, in particular the influence of the spanning structure on the molecular ordering within the archaeal membrane.

Homocysteine and methylmalonic acid concentrations in cerebrospinal fluid: relation with age and Alzheimer's disease.

BACKGROUND: Homocysteine may be involved in the pathogenesis of late onset Alzheimer's disease. It is implicated in the metabolism of several important pathways in the brain. Methylmalonic acid (MMA) is related to the metabolism of branched chained amino acids and fatty acids. OBJECTIVES: To compare cerebrospinal fluid (CSF) total homocysteine and MMA in elderly subjects, patients with Alzheimer's disease, and younger healthy controls. SUBJECTS: CSF samples were obtained from 33 patients under 20 years of age; 28 patients aged 21 to 60 years; 22 normal elderly subjects aged over 60; and 38 Alzheimer patients aged over 60. RESULTS: CSF total homocysteine increased with age (mean (SD): 57 (35) nmol/l in the youngest group v 123 (89) nmol/l in the elderly group (p<0.001)). There was no difference between the elderly group and Alzheimer patients (115 (62) nmol/l). CSF MMA did not differ in the elderly group and the Alzheimer group (38 (13) v 35 (14) ng/ml). In the youngest group, it was significantly higher (60 (15) ng/ml). CONCLUSIONS: CSF total homocysteine is not increased in Alzheimer's disease compared with age matched controls. CSF total homocysteine was correlated with age. The decrease in CSF MMA levels with age eliminates a lack of vitamin B-12 at neuronal level.

Diagnosing immediate reactions to cephalosporins.

BACKGROUND: After penicillins, cephalosporins are the betalactams that most often induce IgE-mediated reactions. The development of diagnostic tests has been delayed, however, because the cephalosporin allergenic determinants have not been properly identified. OBJECTIVE: To evaluate the usefulness of skin tests, serum specific IgE assays, and challenges in diagnosing immediate reactions to cephalosporins and to clarify the pathogenic mechanism of such reactions. METHODS: We studied 76 adults with immediate reactions to cephalosporins, mainly ceftriaxone, cefotaxime, and ceftazidime. Skin tests and serum specific IgE assays were performed for culprit cephalosporins and cefaclor, as well as for penicillin, amoxicillin, and ampicillin. Some subjects with negative results underwent challenges and re-evaluations. Responses to cephalosporins other than the culprit ones were also studied. RESULTS: In the first allergologic work-up, an IgE-mediated hypersensitivity to penicillins and/or cephalosporins was diagnosed in 63 (82.9%) of the 76 patients on the basis of skin-test and/or specific IgE assay positivity. Of the 13 negative patients, eight accepted challenges and underwent re-evaluations. Considering both first- and second-evaluation results, the skin-test-positivity rate increased from 76.3% to 85.5% and that of sepharose-radioimmunoassay positivity from 67.1% to 74.3%. Overall, an IgE-mediated hypersensitivity was diagnosed in 70 patients (in seven after retesting). On the basis of skin-test and CAP-FEIA results, we classified our 76 patients into five groups: group A (three patients), positive only to penicillin reagents; B (17), positive to both cephalosporin and penicillin reagents; C (24), positive to more than one cephalosporin; D (21), positive only to the responsible cephalosporin; E (11) negative to skin tests and CAP-FEIA, including five sepharose-radioimmunoassay positive. CONCLUSIONS: Most immediate reactions to cephalosporins appear to be IgE-mediated. Cephalosporin skin testing and sepharose-radioimmunoassay are useful tools for evaluating these reactions. Cephalosporin IgE-mediated hypersensitivity may be a transient condition; therefore, allergologic exams should be repeated in patients with negative initial allergologic work-ups, including challenges.

Molecular dynamics study of the n-hexane-water interface: towards a better understanding of the liquid-liquid interfacial broadening.

By molecular dynamics simulations, we have studied the hydrophilic-hydrophobic interface between water and n-hexane liquid phases. For all temperatures studied our computed interfacial tension agrees very well with the experimental value. However, the interfacial width calculated from capillary wave theory systematically overestimates the width obtained from fitting either the total density or composition profile. We rationalize the applicability of capillary wave theory for our system by reconsidering the usual value taken for the correlation length. This is motivated by the presence of order at the interface. Possible implications for recent experimental studies on the structure of model alkane-water interfaces are discussed, including the significance of the intrinsic width parameter.

[Food allergy: effect of proteins-lipids and proteins-polysaccharides interactions]. / Allergénicité alimentaire: importance des interactions protéines-lipides et protéines-polysaccharides.

The most widely used ingredients in food formulation are proteins, lipids and polysaccharides. Proteins-lipids and proteins-polysaccharides interactions play a key role in the structure, stability, sensorial and nutritional properties of formulated foods. The objective of the present study is to highlight the importance of proteins-lipids and proteins-polysaccharides interactions, on the immuno-reactivity of allergenic proteins. Two models have been studied, on the one hand refined and not refined oils (soya and sunflower) and soya lecithin, on the other hand mixtures based on peanut proteins and polysaccharides (arabic gum, pectin, xylan). STUDY OF OILS: We have extracted proteins, using a PBS buffer, from refined and not refined oils from soya, sunflower and from soya lecithin, determined protein concentrations and identified allergenic proteins using SDS-PAGE electrophoresis and immuno-blotting. Phospholipids are determined by atomic absorption spectrometry. The protein determination and SDS-PAGE show the presence of a higher amount of proteins in not refined oils and lecithin as compared to refined oils. An important amount of proteins associated to phospholipids are eliminated by degumming on the form of lecithin. On the other hand, residual proteins from refined oils are accompanied by phospholipids. Immuno-blots reveal the presence of a 56 kDa allergen in oils issued from soya seeds and soya lecithin, and the presence of a 67 kDa allergen in oils issued from sunflower seeds. We conclude that the presence or elimination of proteins, especially allergens from oils is linked to amphiphilic association to phospholipids. STUDY OF PEANUT PROTEINS-POLYSACCHARIDES MIXTURES: We have digested in vitro proteins in a dialysis bag using a multi-enzymatic method and characterized proteins and peptides using SDS-PAGE electrophoresis and immuno-blotting. Our results confirm that peanut proteins alone are digested by proteases and that a number of large peptides still have epitopes recognized by anti-peanut proteins antibodies. Our results also show that the presence of polysaccharides changes the peptidic profile after digestion and that, depending on the polysaccharide type, smaller or larger peptides can be obtained in the dialysis bag. Smaller peptides are obtained using pectin whereas larger peptides are obtained using arabic gum and xylan. In the latter case, an increasing amount of peptides reacts to antibodies. Our first observations clearly show the need to better understand modifications of proteins allergenicity induced by the presence of other ingredients such as polysaccharides and lipids, in relation to technological treatments.

Molecular dynamics simulation of surfactin molecules at the water-hexane interface.

The dynamics of surfactin, a lipopeptide surfactant from Bacillus subtilis, has been studied by molecular dynamics at different interfacial concentrations in a water-hexane medium reproducing a hydrophilic/hydrophobic biphasic system. The shapes and orientations of surfactin molecules, as hydrogen bonds and Ramachandran angles, have been recorded to investigate the environment effect on the molecular structure. We demonstrate that the peptidic backbone can exhibit a large flexibility and that conformational motions and structural fluctuations depend strongly on the interfacial concentration. Moreover, we have measured the surface activity of this biosurfactant by computing the interfacial tension and lateral and rotational diffusion coefficients.

[One carbon metabolism and trisomy 21: analysis of the genetic polymorphism]. / Métabolisme des substrats monocarbonés et trisomie 21: analyse de l'impact des polymorphismes génétiques.

Trisomy 21 is the most common chromosome abnormality characterized by the presence of three copies of chromosome 21 in the genome. The clinical disorder attributed to trisomy 21 is Down syndrome. Patients with Down syndrome are heterogeneous in their phenotypic expression. Due to the location of the cystathionine b-synthase gene on chromosome 21, and its involvement in one carbon metabolism, homocysteine levels have been found to be decreased in children with Down syndrome. The study of the regulation of one carbon metabolism in Down syndrome becomes important in light of possible normalization of the metabolic imbalance and the detection of increased sensitivity to therapeutic interventions. Thus, the importance of evaluating single nucleotide polymorphisms in genes involved in one carbon metabolism need to be addressed in individuals with trisomy 21. This review offers an analysis of the impact of these polymorphisms in Down syndrome and their possible implications for phenotypic heterogeneity.

Allergenicity of some isoforms of white sesame proteins.

BACKGROUND: Allergy to sesame seeds is often associated with particularly severe reactions, with a high risk of anaphylaxis. The increase in reports of allergic reactions to sesame is probably due to the growing use of sesame seeds or sesame oil in food. OBJECTIVE: To determine the molecular weights of the proteins in three variety of sesame seeds and to study the isoelectric points and the allergenicity of white sesame proteins. METHODS: Extracts of white, brown and black sesame seeds were prepared. The white sesame extract, mostly used in bakery, was run on SDS-PAGE and two dimensional electrophoresis. Six sera from patients sensitized or symptomatic to sesame seed were used for Western blotting. RESULTS: The protein patterns of the white, brown and black sesame extracts showed major quantitative differences. The white extract had the higher protein concentration and contained 15 proteins of 12-79 kDa, some of them having several acidic isoelectric points. The lowest isoelectric point was 4.9 and the highest was 6.4, giving 35 isoforms. Ten of the 15 proteins (12-57.5 kDa) were recognized by specific IgE. The 12-13 kDa and 22-33 kDa proteins could correspond to the main allergens. CONCLUSION: White sesame seeds contain at least 10 allergenic proteins with acidic isoelectric points. In accordance with previous results, two of them seem to contain the major allergens.

Obesity is associated with decreasing levels of the circulating soluble leptin receptor in humans.

OBJECTIVE: Leptin plays a major role in the regulation of body weight. It circulates in both free and bound form. One of the leptin receptor isoforms exists in a circulating soluble form that can bind leptin. In the present study, we measured the soluble leptin receptor (SLR) levels in lean and obese humans. We investigated the relationship between plasma SLR levels, plasma leptin levels and the degree of obesity. We also examined whether SLR concentrations could be modulated by fat mass loss induced by a 3 month weight-reducing diet. SUBJECTS: A total of 112 obese (age 18-50 y; body mass index (BMI) 30-44 kg/m2; 23 men and 89 women), 38 overweight (age 19-48 y; BMI 25-29 kg/m2; 10 men and 28 women) and 63 lean (age 18-50 y; BMI 17-24 kg/m2; 16 men and 47 women) humans. MEASUREMENTS: A direct double monoclonal sandwich enzyme-linked immunosorbent assay (ELISA) was used for the quantitative measurement of the soluble human leptin receptor. Leptin was measured by radioimmunoassay (RIA). Body composition was assessed by biphotonic absorptiometry DEXA (dual energy X-ray absorptiometry). RESULTS: We observed that the SLR is present in human plasma (range 10-100 ng/ml). SLR levels were lower in obese and overweight than lean subjects (28.7+/-8.8, 40.2+/-14.9, 51.2+/-12.5 ng/ml, respectively) and were inversely correlated to leptin and percentage of body fat (r=-0.74 and r=-0.76; respectively; P<0.0001). The ratio of circulating leptin to SLR was strongly related to the percentage of body fat (r=0.91; P<0.0001). Interestingly a gender difference was observed in SLR levels, which were higher in obese and overweight men than in obese and overweight women. In obese subjects after a 3 month low-calorie diet, SLR levels increased in proportion to the decrease in fat mass. In the gel filtration profile, SLR coeluted exactly with the bound leptin fractions. CONCLUSION: Obesity, in humans is associated with decreasing levels of the circulating soluble leptin receptor (SLR). The relationship of SLR with the degree of adiposity suggests that high SLR levels may enhance leptin action in lean subjects more than in obese subjects.

[Allergenicity of oils]. / Allergénicité des huiles.

Cases of allergy to the oils of groundnut, sunflower, soya and sesame have been described in the literature. In parallel, other authors have affirmed that these oils are not allergenic. The objective of this article is to make the point on this question, to cite the procedures to which the seeds are submitted to extract the oil, to remember that the oils are not composed only of triglycerides and to describe the results of our work. Allergy of oils is a subject that is constantly submitted to controversy and the bibliography does not cease to give contradictory examples. This may be explained by the variations in extraction procedures used by the manufactures, as well as by the conditions of extraction of the proteins in the laboratory.

Detection of moderate hyperhomocysteinemia: comparison of the Abbott fluorescence polarization immunoassay with the Bio-Rad and SBD-F high-performance liquid chromatographic assays.

The importance of accurate methods for homocysteine measurement has been emphasized. We compared the results obtained with the most commonly used high-performance liquid chromatography (HPLC) assay, and two recently commercially available methods: another HPLC and a fluorescence polarization immunoassay, in plasmas from normo- or hyperhomocysteinemic patients. A significant agreement between the different methods in classifying the results as hyper or normal-homocysteinemia was observed. However, a significant difference between the results was found. Standardization is urgently necessary to improve the concordance of homocysteine determination.

The cholesterol-lowering property of soybeans fed to rats is related to the fasting duration.

Numerous factors affect plasma cholesterol and, therefore, represent potential interferences with the specific effects of diet on lipid metabolism. After casein intake, serum cholesterol levels depend on many experimental conditions in rats, such as the type of casein, the presence or absence of cholesterol in the diet, the age and strain of rat, the diet composition, the nutritional status. The effect of fasting duration on selected parameters was studied in adult male Wistar rats fed a 20% casein and 1% cholesterol-based diet. No changes were observed in total serum, lipoproteins-B and HDL cholesterol and in triglyceride values after an 8 h-fast compared to non-fasted animals. A significant decrease was induced in total and lipoproteins-B cholesterol with a 12 h-fast. A prolonged fast resulted in a significant decrease in these parameters and in triglycerides and in HDL-cholesterol levels. Fasted animals fed heated soybean meal instead of casein did not display a marked decrease in serum lipids. It appeared that the fasting effect was more marked in animals fed casein than in animals fed soybeans. These results showed the importance of experimental conditions such as nutritional status of animals when blood samples are taken in studies of the hypocholesterolemic effect of soy protein compared to casein.

Antiparkinsonian agent piribedil displays antagonist properties at native, rat, and cloned, human alpha(2)-adrenoceptors: cellular and functional characterization.

Compared with cloned, human (h)D(2) receptors (pK(i) = 6.9), the antiparkinsonian agent piribedil showed comparable affinity for halpha(2A)- (7.1) and halpha(2C)- (7.2) adrenoceptors (ARs), whereas its affinity for halpha(2B)-ARs was less marked (6.5). At halpha(2A)- and halpha(2C)-ARs, piribedil antagonized induction of [(35)S]guanosine-5'-O-(3-thio)triphosphate (GTPgammaS) binding by norepinephrine (NE) with pK(b) values of 6.5 and 6.9, respectively. Furthermore, Schild analysis of the actions of piribedil at halpha(2A)-ARs indicated competitive antagonism, yielding a pA(2) of 6.5. At a porcine alpha(2A)-AR-Gi1alpha-Cys351C (wild-type) fusion protein, piribedil competitively abolished (pA(2) = 6.5) GTPase activity induced by epinephrine. However, at a alpha(2A)-AR-Gi1alpha-Cys351I (mutant) fusion protein of amplified sensitivity, although still acting as a competitive antagonist (pA(2) = 6.2) of epinephrine, piribedil itself manifested weak partial agonist properties. Similarly, piribedil weakly induced mitogen-activated protein kinase phosphorylation via wild-type halpha(2A)-ARs, although attenuating its phosphorylation by NE. As demonstrated by functional [(35)S]GTPgammaS autoradiography in rats, piribedil antagonized activation by NE of alpha(2)-ARs in cortex, amygdala, and septum. Antagonist properties were also expressed in a dose-dependent enhancement of the firing rate of adrenergic neurons in locus ceruleus (0.125-4.0 mg/kg i.v.). Furthermore, piribedil (2.5-4.0 mg/kg s.c.) accelerated hippocampal NE synthesis, elevated dialysis levels of NE in hippocampus and frontal cortex, and blocked hypnotic-sedative properties of the alpha(2)-AR agonist xylazine. Finally, piribedil showed only modest affinity for rat alpha(1)-ARs (5.9) and weakly antagonized NE-induced activation of phospholipase C via halpha(1A)-ARs (pK(b) = 5.6). In conclusion, piribedil displays essentially antagonist properties at cloned, human and cerebral, rat alpha(2)-ARs. Blockade of alpha(2)-ARs may, thus, contribute to its clinical antiparkinsonian profile.