Effect of argon implantation on solid-state dewetting: control of size and surface density of silicon nanocrystals.

Thermally induced solid-state dewetting of ultra-thin films on insulators is a process of prime interest, since it is capable of easily forming nanocrystals. If no particular treatment is performed to the film prior to the solid-state dewetting, it is already known that the size, the shape and the density of nanocrystals is governed by the initial film thickness. In this paper, we report a novel approach to control the size and the surface density of silicon nanocrystals based on an argon-implantation preliminary surface treatment. Using 7.5 nm thin layers of silicon, we show that increasing the implantation dose tends to form smaller silicon nanocrystals with diameter and height lower than 50 nm and 30 nm, respectively. Concomitantly, the surface density is increased by a factor greater than 20, going from 5 µm-2 to values over 100 µm-2.

Inappropriate prescribing in elderly people with diabetes admitted to hospital.

AIMS: To assess inappropriate prescribing in older people with diabetes mellitus during the month prior to a hospitalization, using tools on potentially inappropriate medicines (PIMs) and potential prescribing omissions (PPOs) and comparing inappropriate prescribing in patients with without diabetes. METHODS: In an observational, prospective multicentric study, we assessed inappropriate prescribing in 672 patients aged 75 years and older during hospital admission. The Beers, Screening Tool of Older Person's Prescriptions (STOPP) and Screening Tool to Alert Doctors to Right Treatment (START) criteria and Assessing Care of Vulnerable Elders (ACOVE-3) medicine quality indicators were used. We analysed demographic and clinical factors associated with inappropriate prescribing. RESULTS: Of 672 patients, 249 (mean age 82.4 years, 62.9% female) had a diagnosis of diabetes mellitus. The mean number of prescribing drugs per patient with diabetes was 12.6 (4.5) vs. 9.4 (4.3) in patients without diabetes (P < 0.001). Of those patients with diabetes, 74.2% used 10 or more medications; 54.5% of patients with diabetes had at least one Beers-listed PIM, 68.1% had at least one STOPP-listed PIM, 64.6% had at least one START-listed PPO and 62.8% had at least one ACOVE-3-listed PPO. Except for the Beers criteria, these prevalences were significantly higher in patients with diabetes than in those without. After excluding diabetes-related items from these tools, only STOPP-listed PIMs remained significantly higher among patients with diabetes (P = 0.04). CONCLUSIONS: Polypharmacy is common among older patients with diabetes mellitus. Inappropriate prescribing is higher in older patients with diabetes, even when diabetes-related treatment is excluded from the inappropriate prescribing evaluation.

Identification of ethyl 2-hydroxy-4-methylpentanoate in red wines, a compound involved in blackberry aroma.

The aroma profile of Bordeaux red wines is known to be marked by blackberry and blackcurrant flavours; this study focused on the fresh blackberry aroma in Bordeaux red wines, using sensory gas chromatography-olfactometry (GC-O) and two-dimensional gas chromatography analysis (GC-GC-MS). A previous HPLC fractionation of red wine extracts on a C18 column produced four fractions with blackberry aromas that were then analysed by GC-O, GC-GC-MS and GC-MS. From these fractions, 10 esters, corresponding to red- or black-berry fruit descriptors, were characterised by GC-MS. Ethyl 2-hydroxy-4-methylpentanoate (ethyl leucate, EL) was identified for the first time in red and white table wines as a compound directly associated with a "fresh blackberry" aroma. Its perception thresholds were 900 and 300µg/l, respectively, in dearomatized red wine and model wine solution (alcohol 12%, pH 3.5), and the average concentration in the various wines was ∼400µg/l. Sensory omission tests highlighted the importance of this compound and identified a perceptive interaction with ethyl butanoate.

Towards Q-PCR of pathogenic bacteria with improved electrochemical double-tagged genosensing detection.

A very sensitive assay for the rapid detection of pathogenic bacteria based on electrochemical genosensing has been designed. The assay was performed by the PCR specific amplification of the eaeA gene, related with the pathogenic activity of Escherichia coli O157:H7. The efficiency and selectivity of the selected primers were firstly studied by using standard Quantitative PCR (Q-PCR) based on TaqMan fluorescent strategy. The bacteria amplicon was detected by using two different electrochemical genosensing strategies, a highly selective biosensor based on a bulk-modified avidin biocomposite (Av-GEB) and a highly sensitive magneto sensor (m-GEC). The electrochemical detection was achieved in both cases by the enzyme marker HRP. The assay showed to be very sensitive, being able to detect 4.5 ng microl(-1) and 0.45 ng microl(-1) of the original bacterial genome after only 10 cycles of PCR amplification, when the first and the second strategies were used, respectively. Moreover, the electrochemical strategies for the detection of the amplicon showed to be more sensitive compared with Q-PCR strategies based on fluorescent labels such as TaqMan probes.

In situ DNA amplification with magnetic primers for the electrochemical detection of food pathogens.

A sensitive and selective genomagnetic assay for the electrochemical detection of food pathogens based on in situ DNA amplification with magnetic primers has been designed. The performance of the genomagnetic assay was firstly demonstrated for a DNA synthetic target by its double-hybridization with both a digoxigenin probe and a biotinylated capture probe, and further binding to streptavidin-modified magnetic beads. The DNA sandwiched target bound on the magnetic beads is then separated by using a magneto electrode based on graphite-epoxy composite. The electrochemical detection is finally achieved by an enzyme marker, anti-digoxigenin horseradish peroxidase (HRP). The novel strategy was used for the rapid and sensitive detection of polymerase chain reaction (PCR) amplified samples. Promising resultants were also achieved for the DNA amplification directly performed on magnetic beads by using a novel magnetic primer, i.e., the up PCR primer bound to magnetic beads. Moreover, the magneto DNA biosensing assay was able to detect changes at single nucleotide polymorphism (SNP) level, when stringent hybridization conditions were used. The reliability of the assay was tested for Salmonella spp., the most important pathogen affecting food safety.

Synthesis and biological activity of novel acridinylidene and benzylidene thiazolidinediones.

A novel set of acridinylidene thiazolidinediones and benzylidene thiazolidinediones was synthesized by nucleophilic addition of cyanoacrylates. Some of these compounds were evaluated for their glucose lowering capability and their effects on the triglyceride level in alloxan diabetic mice.

Synthesis and schistosomicidal activity of new substituted thioxo-imidazolidine compounds.

Synthesis and physico-chemical properties of 3-benzyl-5-(4-fluoro-benzylidene)-1-methyl-2-thioxo-imidazolidin-4-ones, 5-benzylidene-3-(4-nitro-benzyl)-2-thioxo-imidazolidin-4-ones and 4-acridin-9-ylmethylene-1-benzyl-5-thioxo-imidazolidin-2-ones compounds are described. These thioxo-imidazolidine derivatives were prepared by alkylation and condensation with 4-fluoro-benzaldehyde or nucleophilic Michael addition with cyanoacrylates. The schistosomicidal activity of 3-benzyl-5-(4-fluoro-benzylidene)-1-methyl-2-thioxo-imidazolidin-4-one compounds was evaluated.

LexA-binding sequences in Gram-positive and cyanobacteria are closely related.

The lexA gene of the cyanobacterium Anabaena sp. strain PCC7120 has been cloned by PCR amplification with primers designed after TBLASTN analysis of its genome sequence using the Escherichia coli LexA sequence as a probe. After over-expression in E. coli and subsequent purification, footprinting experiments demonstrated that the Anabaena LexA protein binds to the sequence TAGTACTAATGTTCTA, which is found upstream of its own coding gene. Directed mutagenesis and sequence comparison of promoters of other Anabaena genes, as well as those of several cyanobacteria, allowed us to define the motif RGTACNNNDGTWCB as the LexA box in this bacterial phylum. Substitution of a single nucleotide in this motif present in the Anabena lexA promoter is sufficient to enable it to bind the Bacillus subtilis LexA protein. These data indicate that Cyanobacteria and Gram-positive bacteria are phylogenetically closely related.

Effect of structure on antibiotic action of new 9-(ethylthio)acridines.

Six new 9-(ethylthio)acridine derivatives were examined for antibacterial and antifungal activities with 10 bacterial and 8 yeast strains. The only active compounds were 2- and 3-amino derivatives. The observed MICs (mg/L) for 2-amino-9-(ethylthio)acridine (possessing the highest biological activity) were 12 (P. mirabilis), 30 (B. subtillis), 60 (C. freundii), 90 (E. coli), 128 (E. vulneris) and 500 (S. marcescens and S. aureus). Both amino derivatives have also lowest half-wave potential (E1/2) and field Swain-Lupton constants (describing oxidoreduction behavior) what supports the importance of acridine ion formation in the mechanism of antimicrobial action.

New pyridoquinoline derivatives as potential inhibitors of the fluoroquinolone efflux pump in resistant Enterobacter aerogenes strains.

Enterobacter aerogenes, one of the most frequently isolated nosocomial pathogens in France, is exhibiting increasing multidrug resistance mechanisms associated with a change in membrane permeability. For drugs of the quinolone family, mutations in the target and active efflux play a prominent role in the resistance. We report here the effect of several pyridoquinoline derivatives that restore a noticeable fluoroquinolone accumulation to resistant strains that overexpress the MarA activator. Studies of the energy-dependent quinolone efflux indicate that the most efficient derivatives tested probably inhibit the resistance process by acting as substrate competitors on the pump extruding intracellular norfloxacin.

Studies on the antimutagenesis of Phyllanthus orbicularis: mechanisms involved against aromatic amines.

Phyllanthus orbicularis is a medicinal plant, endemic to Cuba, whose aqueous extract has proven antiviral properties. This plant extract is being studied for treatment of viral diseases in animals and humans. Antimutagenic activities of this plant aqueous extract have been investigated as an additional and possible valuable property. Antimutagenesis was assayed against the mutagenic activity of m-phenylenediamine (m-PDA), 2-aminofluorene (2-AF), 1-aminopyrene (1-AP), 2-aminoanthracene (2-AA) and 9-aminophenantrene (9-AP) in Salmonella typhimurium (S. typhimurium) YG1024, in different co-treatment approaches. This plant extract produced a significant decrease of the mutagenesis mediated by these aromatic amines (AA) in the following order: m-PDA>2-AA>2-AF>9-AP>1-AP. Interactions with S9 enzymes and transformation of promutagenic amines and their mutagenic metabolites by chemical reactions to non-mutagenic compounds are proposed as possible mechanisms of antimutagenesis. Mutagenesis mediated by m-PDA was almost completely abolished when S9 mixture was co-incubated with the plant extract during 40 min, previous to the addition of the m-PDA and bacterial cells to the assay. Similar results were found with 2-AA and 1-AP, but the reduction of the mutation rate was not so dramatic. In contrast, the most significant antimutagenic effect against 2-AF and 9-AP was seen when these chemicals were co-incubated with the plant extract, before addition of the S9 mixture and bacterial cells to the assay. Therefore, inhibition or competition for S9 enzymes seems to be the main antimutagenic mechanism of this plant extract against m-PDA, 2-AA and 1-AP, whilst a chemical modification of 2-AF and 9-AP into non-promutagenic derivatives is likely to be the main mechanism of antimutagenesis against both compounds.

Alkyl and aryl substituted corroles. 2. Synthesis and characterization of linked "face-to-face" biscorroles. X-ray structure of (BCA)Co(2)(py)(3), where BCA represents a biscorrole with an anthracenyl bridge.

The synthesis, spectroscopic properties, and electrochemistry of (BCA)Co(2) and (BCB)Co(2) are described where BCA and BCB represent biscorroles linked by an anthracenyl (A) or a biphenylenyl (B) bridge. The pyridine and CO binding properties of (BCA)Co(2) and (BCB)Co(2) are also presented, and one of the compounds in its pyridine-ligated form, (BCA)Co(2)(py)(3), is structurally characterized. The data on the biscorroles are compared on one hand to the monocorrole having the same substitution pattern and on the other hand to bisporphyrins having two Co(II) ions and the same anthracenyl or biphenylenyl linkers in order to better understand the interaction which occurs between the two corrole macrocycles. A parallel study on five different Co(III) phenyl-substituted corroles showed that bis-pyridine and mono-CO adducts are readily formed from the complexes in CH(2)Cl(2). This present paper examines how the ligand binding properties and electrochemistry of these Co(III) corroles are modified by the anthracenyl or biphenylenyl bridge which links the two macrocycles in a face to face orientation. An X-ray crystal structure was obtained for the tris-pyridine adduct of the anthracenyl bridged derivative, (BCA)Co(2)(py)(3), and gives the following results: C(127)H(99)Co(2)N(11).2CHCl(3), M = 2135.90, triclinic, space group P&onemacr;, a = 13.2555(5) A, b = 18.6406(8) A, c = 22.2140(9) A, alpha = 94.186(9) degrees, beta = 102.273(9) degrees, gamma = 94.205(9) degrees, V = 5326.8(4) A(3), 9293 independent reflections collected, R(F) = 0.066.

Expression of the Pasteurella multocida ompH gene is negatively regulated by the Fur protein.

The fur gene of Pasteurella multocida has been cloned by complementation of an Escherichia coli fur mutant. The P. multocida fur gene, which encodes a predicted protein of 147 amino acids, displaying the highest identity (89%) with the same protein of Haemophilus influenzae, is negatively regulated by its own product. By construction of a P. multocida fur mutant, it has been demonstrated that the ompH gene, encoding a major structural protein of the outer membrane, presenting high antigenicity power, is negatively regulated by iron and glucose. Furthermore, wild-type and fur-defective cells of P. multocida show the same level of virulence.

Origin and significance of the production of carbon dioxide during the ozonization of 13C-labeled D-glucose at different pH values.

[1-(13)C], [2-(13)C] and [6-(13)C] D-glucose were, respectively, ozonized in a semi-batch reactor in acidic and basic conditions. The composition of the gas phase was evaluated by on-line mass spectrometry measurements. The quantitative and isotopic analyses of the carbon dioxide formed during ozonization are presented and discussed. The data, correlated with previous literature results, clearly show that at pH 2.5 the production of carbon dioxide from C-6 and C-1 carbon atoms is nearly equivalent. Conversely, at higher pH values, CO(2) is released with a greater selectivity from the reducing end. The importance of the decarboxylation reaction in the formation of by-products with fewer than six carbon atoms is also demonstrated.

Analysis of pyridoquinoline derivatives by liquid chromatography/atmospheric pressure chemical ionization mass spectrometry.

A method using liquid chromatography/atmospheric pressure chemical ionization mass spectrometry (LC/APCI-MS) has been developed for the characterization and determination of pyridoquinoline derivatives 4,6-bis(dimethylaminoethylamino)-2,8,10-trimethylpyrido[3,2-g]quinoline, 4,6-bis(dimethylaminoethoxy)-2,8,10-trimethylpyrido[3,2-g]quinoline and 4,6-bis[(dimethylaminoethyl)thio]-2,8,10-trimethylpyrido[3,2-g] quinoline, all with potential antitumor properties. LC separation was performed on a conventional C18 column using a binary mobile phase composed of acetonitrile and 50 mM aqueous ammonium formate at pH 3. The APCI mass spectra obtained showed that proton addition giving [M + H]+ was the common mode of ionization to the amino- and thiopyridoquinolines, whereas the alkoxypyridoquinoline was identified by the main formation of the [M - (C2H3)N(CH3)2 + H]+, followed by the [M + H]+ ion. The LC separation conditions and MS detection parameters were optimized for the determination. The analytical method was also applied to the determination of these pyridoquinoline derivatives in fetal calf serum using liquid-liquid extraction with dichloromethane. Acceptable recovery values were obtained, ranging between 45 and 98%.

Virulence of Pasteurella multocida recA mutants.

In order to determine the role of the RecA protein in the virulence of Pasteurella multocida, a recA mutant was constructed and used in studies of virulence and competition in relation to wild-type strain. To achieve this, firstly, the recA gene was isolated and sequenced, showing an Escherichia coli-like SOS box and encoding a protein of 354 amino acids which has the closest identity with the Haemophilus influenzae RecA protein. Further, the recA mutant was constructed, by inactivating this gene by single recombination of a suicide plasmid containing an internal region of the P. multocida recA gene, and shown to be more sensitive to UV radiation than the parental strain. The P. multocida mutant was slightly attenuated in virulence, as indicated by the LD(50), the time of death of infected animals, and a failure to compete with the wild-type strain in mixed infections. Compared to the parent strain, the mutant had a similar growth rate but a longer lag phase. These data suggest that the diminished virulence of the recA mutant as well as its failure in competition were more a consequence of the long lag phase rather than a direct effect of the inactivation of the recA gene on genes involved in virulence.

Role of botrytized grape micro-organisms in SO2 binding phenomena.

AIMS: The purpose of this work was to study the involvement of micro-organisms, which develop together with Botrytis cinerea on grapes, in the SO2 binding power of musts. METHODS AND RESULTS: Yeasts and bacteria were involved. Most bacteria were acetic acid bacteria, mainly of the Gluconobacter genus. Unlike oxidative yeasts, Gluconobacter produce gluconic acid (in balance with delta-gluconolactone) from glucose, 5-oxofructose from fructose and dihydroxyacetone from glycerol. Production of carbonyl compounds from other sugars and polyols was not detected or was very weak. CONCLUSION: Acetic acid bacteria are responsible for the increases in SO2 binding power of musts from botrytized grapes by oxidizing the three main sugars of these grapes. SIGNIFICANCE AND IMPACT OF THE STUDY: Up to 80% of the SO2 binds with products of Gluconobacter which easily grow on 'botrytized' grapes. Depending on climatic conditions, some vintages are particularly difficult to stabilize.