Optical matter: crystallization and binding in intense optical fields.

Properly fashioned electromagnetic fields coupled to microscopic dielectric objects can be used to create arrays of extended crystalline and noncrystalline structures. Organization can be achieved in two ways: In the first, dielectric matter is transported in direct response to the externally applied standing wave optical fields. In the second, the external optical fields induce interactions between dielectric objects that can also result in the creation of complex structures. In either case, these new ordered structures, whose existence depends on the presence of both light and polarizable matter, are referred to as optical matter.

[Cases of imported cholera in France, summer 2005. A. Tarantola for the incident management teams]. / Cas de choléra d'importation en France, été 2005. A. Tarantola pour les groupes de gestion des incidents.

Cholera is a bacterial infection, which causes digestive symptoms and massive diarrhoea. It may lead to dehydration and death if appropriate medical management is not rapidly initiated. Most cases of infection by choleric vibrio, however, remain symptom-free or may mimic common gastroenteritis. A review of two cases of imported cholera in France in the summer of 2005 and the community- and hospital-based investigation, which they triggered, enabled the incident management teams to assess risks of transmission. There were no secondary cases among 58 hospital contacts and 15 family contacts of the cases. Clinicians will find a discussion of possible clinical presentations and the risk of secondary transmission, in the context of progressing epidemics in countries, which have maintained close ties with France.

Comparison of various methods and reagents for species identification of Staphylococcus aureus positive or negative for the mecA gene.

The reliability of various methods for species identification of Staphylococcus aureus was evaluated. A total of 135 coagulase-positive (SA) or -negative (SS) staphylococcal isolates were tested, including methicillin-resistant (MR) and -susceptible (MS) strains. When the nuc gene which encodes the S. aureus thermonuclease (TNase) was amplified in a multiplex PCR simultaneously with the mecA gene which encodes for the MR-associated penicillin-binding protein 2a of staphylococci, the nuc amplification showed full agreement with the results of the coagulase test. TNase detected by an enzymatic method or as protein in a sandwich ELISA identified S. aureus with nearly the same precision as the PCR. The Staphylase, Monostaph and Staphaurex agglutination kits were all reliable for identification of MSSA, but not for MRSA. Most of the negative MRSA strains were identified by the Pastorex agglutination kit, in which reagents for fibrinogen receptor and protein A detection have been supplemented with antibodies for capsular polysaccharides of the serotypes 5 and 8. These results show that detection of the nuc gene or its TNase product is highly reliable for identification of both MRSA and MSSA strains, while various widely used agglutination kits do not show the same reliability for identification of MRSA strains.

Genetic analysis of the cap5 locus of Staphylococcus aureus.

Staphylococcus aureus expresses at least eight distinct serotypes of capsular polysaccharide (CP). Gene clusters involved in the expression of serotypes 1, 5 and 8 have been cloned and sequenced. In this report we describe the isolation and analysis of serotype 5 capsular polysaccharide-defective mutants. A naturally occurring cap mutation in the laboratory strains 8325-4 and RN4220 was mapped to the cap5E gene by genetic complementation. The cap5H-K genes were shown to be responsible for CP5 serotype specificity by transduction and complementation.

Nonlinear identification of NMR spin systems by adaptive filtering.

In this paper, we present two new methods for identifying NMR spin systems. These methods are based on nonlinear adaptive filtering. The spin system is assumed to be time-invariant with memory. The first method uses a truncated discrete Volterra series to describe the nonlinear relationship between excitation (input) and system response (output). First-, second-, and third-order kernels of this series are estimated employing the least mean square (LMS) algorithm. Three parallel filters can then model the NMR spin system so that its output is no more than simple sum of three convolution products between combinations of the input signal and filters coefficients. It is also shown that the contribution of the Volterra second-order term to the total system response is neglected compared with the contributions of the first- and the third-order terms. In the second identification method, the output signal is related to the input signal through a recursive nonlinear difference equation with constant coefficients. The LMS algorithm is used again to estimate the equation coefficients. The two methods are validated with a simulated NMR system model based on Bloch equations. The results and the performances of these methods are analyzed and compared. It is shown that our methods permit a simple identification of NMR spin systems. The field of applications of this study is promising in the optimization of NMR signal detection, especially in the cases of low signal-to-noise ratios where optimum signal filtering and analysis must be performed.

Structure of the type 5 capsular polysaccharide of Staphylococcus aureus.

The Staphylococcus aureus type 5 capsular polysaccharide is composed of 2-acetamido-2-deoxy-L-fucose (1 part), 2-acetamido-2-deoxy-D-fucose (1 part), and 2-acetamido-2-deoxy-D-mannuronic acid (1 part). On the basis of methylation analysis, optical rotation, high-field one- and two-dimensional 1H- and 13C-n.m.r. experiments, and selective cleavage with 70% aqueous hydrogen fluoride, the polysaccharide was found to be a partially O-acetylated (50%) polymer of the repeating trisaccharide unit, [----4)-3-O-Ac-beta-D-ManpNAcA-(1----4)-a-L-FucpNAc-(1----3) -beta-D-FucpNAc-(1----]n.

Adsorption-desorption and leaching of phenylurea herbicides on soils.

Adsorption-desorption equilibria of phenylurea herbicides (chlortoluron, isoproturon, metobromuron, chloroxuron, difenoxuron) were determined in two different soils. Organic carbon content of the soils ranged from 1.1-5.6% and the clay fraction from 25-30%. Spiked aqueous suspensions of soils were centrifuged and urea derivative concentrations in the aqueous phase were determined using a HPLC-UV system. Adsorption isotherms conformed to the Freundlich equation. Freundlich K(f) values indicated that organic carbon was the main factor affecting urea sorption in the studied soils. The R(f)values calculated from the soil column displacement closely correlated with the adsorption K(f) values. Results indicated that chloroxuron and difenoxuron were sorbed to a larger extent than the other three ureas on the two soils; as expected their mobilities through soil columns were very limited. The similarity between the molecular structures of chloroxuron and difenoxuron enables us to assume the phenoxy group to be the main structural feature in the adsorption phenomenon. The relationships between sorption, leaching and some characteristics of urea molecules such as water solubility and octanol-water partition coefficient were also examined.

[The current status of research on a cholera vaccine]. / Etat actuel des recherches sur le vaccin anticholérique.

Cholera remains today a major health problem in most developing countries. The long-term control of cholera depends on the improvement of hygiene but this is a distant goal for many countries. The availability of an effective cholera vaccine is thus important for the prevention of cholera in such countries. More than a century after the first attempt to vaccinate against cholera by Ferran in Spain, there is still no truly effective cholera vaccine. A bacterial fraction vaccine, referred to as CH1 +2 was prepared by Professor A. Dodin. A field trial of this vaccine was carried out in Zaire in 1983. Significant protection was observed but this vaccine was not evaluated in additional trials. Two other oral cholera vaccines, developed in Sweden and in the USA, were widely experimented on human beings: a combination of cholera toxin B-subunit and inactivated bacterial cells, and a live attenuated vaccine containing the genetically manipulated Vibrio cholerae O1 strain CVD 103-HgR. Despite their efficiency as evaluated in field trials (inactivated vaccine) or on volunteers (live vaccine), these vaccines have drawbacks that may limit their usefulness as practical vaccines. Protection induced by the inactivated vaccine was transient in young children, lasting only approximately for six months. One of the safety concerns associated with live vaccines is a possible reversion to virulence. Efforts should be continued to find a better cholera vaccine. A new vaccine development program based upon the hypothesis that immunoglobulin G directed to the O-specific polysaccharide of Vibrio cholerae O1 could confer protective immunity to cholera. This program may lead to the development of a cholera conjugate vaccine to elicit protection in infants.

[In vitro sensitivity of Vibrio cholerae serotype 0:139 to an intestinal antiseptic tiliquinol-tilbroquinol combination]. / Sensibilité in vitro de Vibrio cholerae du sérotype O:139 à un antiseptique intestinal l'association tiliquinol-tilbroquinol.

O:139 is a new serotype of Vibrio cholerae that is not agglutinated by an O:1 antiserum but causes epidemics of cholera. Strains of O:139 serotype are resistant to O/129 compound and many antibiotics but are sensitive to tetracyclines and tiliquinol-tilbroquinol (Intétrix). The clinical management of the patients infected with serotype O:139 is identical to that of usual choleric patients. However, the immunological difference with O:1 serotype must lead to reconsider both the diagnosis and the vaccinating strategies of cholera.

[Simplified vibriocidal antibody titer performed on a drop of blood]. / Titrage simplifié des anticorps vibriocides à partir d'une goutte de sang.

We report a simplified technique for vibriocidal antibody test in underprivileged people in tropical area. The test is performed on a drop of blood sampled on a disc of blotting paper. It avoid taking of large quantities of blood in timid underfed people who are often solicited. Its reading is rapid and easy by the naked eye owing to staining viable germs violet by the neotetrazolium succinate. Tested in mice and humans, the simplified method gave data well correlated to those obtained with the standard test on serum for vibriocidal titres higher than (or equal to) 1/40.

[Resistance of Vibrio cholerae 0:1 to the 0/129 compound and multiresistance to antibiotics]. / Résistance de Vibrio cholerae O:1 au composé O/129 et multirésistance aux antibiotiques.

The authors present a study of the in vitro susceptibility to O/129 compound and usual antibiotics of 29 strains of V. cholerae O:1 biotype El Tor isolated during epidemics in miscellaneous countries over the world from 1982 to 1991. Several identical isolates from the same epidemic are represented by one strain. Susceptibility testing by diffusion method and MICs by agar dilution method are used. The data show that the resistance to O/129 compound is often associated with the resistance to usual antibiotics such as trimethoprim, sulphonamides, chloramphenicol, ampicillin and tetracycline. This resistance to the vibrostatic compound leads to a double problem of diagnosis and therapy. The nitrofuranes derivatives and tiliquinol-tilbroquinol association, an intestinal antiseptic, are the most active antimicrobial agents as well on the strains O/129 sensitive as on the strains O/129 resistant.

[Value of vibriocidal antibody research in endemic areas of Vibrio cholerae 0:1]. / Intérêt de la recherche des anticorps vibriocides en zones d'endémie à Vibrio cholerae O:1.

We made vibriocidal antibody titration in the serum of some populations in Algeria and in Mali either during or between cholera epidemics. The seropositivity rate was 43.3% in healthy contacts in Alger in 1990 during an epidemic of cholera. For 12/16 healthy contacts examined two times in a 25-day interval, the seropositivity rate increased during the epidemic and the mean of antibody titres rose 8.88 folds. In Constantine, 53% of 195 blood donors had significant titres of vibriocidal antibodies in 1992, 6 years after an epidemic of cholera. The seropositivity rate in population seemed decreasing during this year. In Bamako, 46% of selected patients had significant vibriocidal antibody titres 8 years after the last epidemic of cholera in Mali. Seven of 10 children born after the epidemic had vibriocidal antibodies. These data confirm the persistence of vibriocidal antibodies in population during many years. The importance of the seropositivity rate in healthy contacts and in children born during a non epidemic period shows that asymptomatic infection is frequent and that Vibrio cholerae O:1 may be circulating in population between epidemics. As part of surveillance of cholera outbreaks in endemic areas, it might be of interest to study on a regular basis the vibriocidal antibody seropositivity rate in populations.

[Isolation of Vibrio strains in French coastal waters and infection with Vibrio cholerae non-O1/non-O139]. / Isolement de vibrions dans les eaux côtières françaises et infection à Vibrio cholerae non-O1/non-O139.

OBJECTIVE: Although the incidence in France of V. cholerae non-O1/non-O139 infection in man has increased since 1996, it remains low (7 cases in 1999). After the death in 1994 of an immunodepressed patient presenting a skin lesion showing superinfection by a strain of non-O1/non-O139 V. cholerae following exposure to seawater, we examined 22 samples of sea-water collected from 20 French coastal areas (Mediterranean coast). METHODS: The sea-water samples were filtered and enriched with alkaline peptone water (APW), and the strains of Vibrio were isolated on TCBS, SS and BCP media and identified using the API 20 E system (bioMérieux, France). RESULTS: We isolated 6 strains belonging to 3 species of Vibrio: 2 V. cholerae (non-O1/non-O139), 3 V. parahaemolyticus and 1 V. alginolyticus. One of the V. cholerae strains was isolated from sea-water sampled at the coastal town in which the patient had been staying. The seawater strains exhibited high sensitivity (MIC determined by agar dilution) to the following antibiotics: aminoglycosides, tetracyclines, azithromycin, cotrimoxazole, rifampicin and fluoroquinolones. The beta-lactams were very active against strains of V. cholerae isolated from seawater, while the strain isolated from this patient presented a new carbenicillinase (CARB-6) recently described. CONCLUSION: The presence of Vibrio in seawater along the French coast-line constitutes a risk for immunocompromised patients, and the severity of Vibrio infections warrants improved monitoring both of these organisms and of the marine environment. In addition, awareness on the part of doctors would allow patients at risk to be warned against these dangers.

[Vibrio vulnificus septicemia transmitted through a wound caused by a crustacea]. / Septicémie à Vibrio vulnificus secondaire à une blessure par écrevisse.

INTRODUCTION: Vibrio vulnificus proliferates during the summer in salt water where it infects the crustaceans. Expression of its pathogenicity depends on the underlying condition and mode of contamination. OBSERVATION: A 65 year-old man presented with a Vibrio vulnificus septicaemia of cutaneous origin, transmitted when he cut himself with a crawfish. The severity of the infection was enhanced by severe immuno-depression and haemochromatosis. The infection regressed with appropriate antibiotherapy. COMMENTS: Severe V. vulnificus infections are rare. Depending on the underlying condition and mode of contamination, one can distinguish between benign gastro-enteritis, local occasionally devastating infections and usually fatal septicaemia. CONCLUSION: Even the most severe forms of V. vulnificus infections may be cured with early and well adapted anti-infectious treatment.

[Cholera in a Paris resident with no history of travel. A case report]. / Choléra autochtone à Paris. Une observation.

BACKGROUND: Cases of imported cholera are frequently observed, but cholera almost never occurs in subjects who have never travelled to an endemic area. In the last 30 years, 4 cases have been reported. We report an indigenous case diagnosed in Paris in September 1996. CASE REPORT: The patient was hospitalized for severe dehydration and acute renal failure. Cultures of a fecal specimen grew Vibrio cholerae O1 Ogawa serotype. An epidemiological study was conducted to identify the vehicle and mode of contamination and suggested that this case was associated with the consumption of fresh sorrel imported from West Africa. No other cases were identified in contacts of the patient. DISCUSSION: Asymptomatic carriage of V. cholerae is rare. However, air travel has allowed people to arrive in non-endemic areas during the incubation period. The agent may also be transported in contaminated foods. Cholera should be suspected in all adults presenting acute watery diarrhea with severe dehydration. History taking should also look for risk exposure and these patients should be systematically asked about possible exposures.

[Cholera update and vaccination problems]. / Actualité du choléra et problématique vaccinale.

Cholera remains an important public health problem. The long-term control of cholera depends on good personal hygiene, uncontaminated water supply and appropriate sewage disposal. However, the improvement of hygiene is distant goal for many countries. Thus the availability of an effective cholera vaccine is important for the prevention of cholera in these countries. Research on new cholera vaccines has mainly focused on oral formulations that stimulate the mucosal secretory immune system. Two oral cholera vaccines were experimented on large scale in human. The first vaccine, containing inactivated bacterial cells and B-subunit of cholera toxin, has been tested in Bangladesh from 1985 to 1989. This vaccine, according to WHO, may prove useful in the stable phase of refugee/displaced person crises, especially when given preventively. The second vaccine is a live attenuated vaccine containing the genetically manipulated Vibrio cholerae O1 strain CVD 103-HgR. Despite its efficacy in adult volunteers, results of a large-scale field trial carried-out in Indonesia for 4 years have shown a surprisingly low protection. Moreover, one of the safety concerns associated with live cholera vaccine is a possible horizontal gene transfer and recombination event leading to reversion to virulence. A new vaccine development program for cholera is based upon the hypothesis that immunoglobulins G directed to the O-specific polysaccharide of Vibrio cholerae O1 could confer protective immunity to cholera by inactivating the inoculum on intestinal mucosal surface. This program may lead to the development of cholera conjugate vaccines to elicit protection in infants.

Respiratory activity is essential for post-exponential-phase production of type 5 capsular polysaccharide by Staphylococcus aureus.

Capsule formation is believed to have a significant role in bacterial virulence. To examine the possible involvement of capsular polysaccharide (CP) from Staphylococcus aureus in the pathological mechanisms associated with staphylococcal infections, we investigated the influence of respiratory activity on type 5 CP production by S. aureus grown in the presence of various concentrations of dissolved oxygen or nitrate. The effects of several metabolic inhibitors (arsenite, cyanide, azide, trimethylamine N-oxide, 2-heptyl-4-hydroxyquinoline N-oxide, and 2,4-dinitrophenol) were also tested. The metabolism of the bacteria was estimated by measuring their reductive capacity and by monitoring the pH and concentrations of fermentation products. Type 5 CP was always produced by S. aureus during the exponential phase of growth under all culture conditions tested. In contrast, post-exponential-phase CP production appeared to be strictly dependent on the respiratory activity. Since post-exponential-phase CP production contributes at least two-thirds of the total CP obtained, the influence of S. aureus respiration on CP production might be of some importance in the process of infection.

Immunoprotective activity of capsular polysaccharide in Klebsiella pneumoniae ribosomal preparations does not involve ribonucleic acid.

Two peaks were obtained by cesium chloride density gradient ultracentrifugation of Klebsiella pneumoniae ribosomal preparations. Peak I contained capsular polysaccharide, lipopolysaccharide, protein, and less than 0.5% ribonucleic acid. Peak II consisted mainly of ribonucleic acid, with low amounts of protein and capsular polysaccharide. Expressed as capsular polysaccharide content, the 50% protective dose of peak I and of nonfractionated ribosomal preparations was nearly constant (2.6 and 1.2 ng, respectively). Since peak I contained less than 0.5% ribonucleic acid, these results provide evidence that ribosomal ribonucleic acid is not required for protection of mice by K. pneumoniae capsular polysaccharide which contaminates ribosomal preparations.