Note: Efficient diode laser line narrowing using dual, feed-forward + feed-back laser frequency control.

We have achieved distributed feedback laser diode line narrowing by simultaneously acting on the diode current via a feed-back loop and on an external electrooptic phase modulator in feed-forward actuator. This configuration turns out to be very efficient in reaching large bandwidth in the phase correction: up to 15 MHz with commercial laser control units. About 98% of the laser power undergoes narrowing. The full width at half maximum of the narrowed optical spectrum is of less than 4 kHz. This configuration appears to be very convenient as the delay in the feed-forward control electronics is easily compensated for by a 20 m optical fiber roll.

Optical amplification of Pr3+ -doped ZBLA channel waveguides for visible Laser emission.

We report on the first observation of optical signal amplification in the visible range into praseodymium doped ZBLA glass channel waveguides obtained by ion exchange. Up to 30% signal amplification was obtained at 639 nm. This result shows the potential of rare earth doped fluoride glasses in the form of channel waveguides for integrated solid state visible laser sources.

In-vacuum Faraday isolation remote tuning.

In-vacuum Faraday isolators (FIs) are used in gravitational wave interferometers to prevent the disturbance caused by light reflected back to the input port from the interferometer itself. The efficiency of the optical isolation is becoming more critical with the increase of laser input power. An in-vacuum FI, used in a gravitational wave experiment (Virgo), has a 20 mm clear aperture and is illuminated by an almost 20 W incoming beam, having a diameter of about 5 mm. When going in vacuum at 10(-6) mbar, a degradation of the isolation exceeding 10 dB was observed. A remotely controlled system using a motorized lambda=2 waveplate inserted between the first polarizer and the Faraday rotator has proven its capability to restore the optical isolation to a value close to the one set up in air.

Ultraviolet-absorbing compounds in milk are related to forage polyphenols.

The aim of this work was to characterize UV-absorbing compounds (UAC) in milk in relation to diet. In winter, 4 groups of cows each received a different diet: concentrate rich containing 35% cocksfoot hay (CCH), maize silage (MS), rye grass silage (RS), or rye grass hay (RH). In summer, 2 additional diets were given: mountain grassland hay (GH) and mountain grassland pasture (GP). Polyphenols were analyzed by HPLC and Folin reaction on forages and UAC were extracted from milks and analyzed by HPLC. In forages, the number of polyphenols was lowest in MS (57) and greatest in GP (85). Twenty-four peaks were identified, accounting for 28 to 47% peak area at 280 nm. Caffeoyl compounds and flavonoid glycosides were mainly found in RH, GH, and GP. Hydrolyzed compounds such as hydroxycinnamic acids and aglycones were found in MS and RS. Estimated amounts of polyphenols were lowest for MS (3.7 g/kg), roughly similar for CH, RS, and RH (about 15 g/kg), and greatest for GH and GP (21.6 and 35.3 g/kg, respectively). About 230 different peaks were separated in milks. Milks from RH and GP contained the lowest (87) and the greatest (127) numbers of peaks, respectively. Only 10 peaks were identified, accounting for 21 to 54% of the total spectra area. In addition to the major compound hippuric acid, phenylacetic acid, benzoic acid, 4-hydroxybenzoic acid benzaldehyde, catechol, and small amounts of ferulic acid were found in varying amounts depending on the diet. Flavonoids such as quercetin, luteolin, and apigenin were also present. Hippuric acid was clearly related to the presence of caffeoylquinic compounds in forages. Other identified UAC may originate essentially from forage simple polyphenols or from cell wall aromatics. Some of the several unknown compounds may also originate from the transformation of other nutrients. Estimated amounts of UAC were widely variable within each animal group. They were surprisingly high in CCH and roughly similar in all milks from preserved forages (about 3.6 mg/L), with generally greater values for GH milks, whereas the greatest amount was found in GP milks (13.3 mg/L). Hierarchical clustering clearly discriminated the 6 diets, showing that there were major differences in GP milks. Some UAC were specific to one or a group of diets. Ultraviolet-absorbing compounds are therefore a potential tool to distinguish between milks according to diet. In addition, they may have a bioactive effect on milk component conservation or on human health.

Characterization of the yeast ecosystem in grape must and wine using real-time PCR.

The complex microbial ecosystem of grape must and wine harbours a wide diversity of yeast species. Specific oligonucleotide primers for real-time quantitative PCR(QPCR) were designed to analyse several important non-Saccharomyces yeasts (Issatchenkia orientalis, Metschnikowia pulcherrima, Torulaspora delbrueckii, Candida zemplinina and Hanseniaspora spp.) and Saccharomyces spp. in fresh wine must, during fermentation and in the finished wine. The specificity of all primer couples for their target yeast species were validated and the QPCR methods developed were compared with a classic approach of colony identification by RFLP-ITS-PCR on cultured samples. Once the methods had been developed and validated, they were used to study these non-Saccharomyces yeasts in wine samples and to monitor their dynamics throughout the fermentation process. This study confirms the usefulness and the relevance of QPCR for studying non-Saccharomyces yeasts in the complex yeast ecosystem of grape must and wine.

Brettanomyces bruxellensis evolution and volatile phenols production in red wines during storage in bottles.

AIMS: The presence of Brettanomyces bruxellensis is an important issue during winemaking because of its volatile phenols production capacities. The aim of this study is to provide information on the ability of residual B. bruxellensis populations to multiply and spoil finished wines during storage in bottles. METHODS AND RESULTS: Several finished wines were studied. Brettanomyces bruxellensis populations were monitored during two and a half months, and volatile phenols as well as chemical parameters regularly determined. Variable growth and volatile phenols synthesis capacities were evidenced, in particularly when cells are in a noncultivable state. In addition, the volatile phenol production was clearly shown to be a two-step procedure that could strongly be correlated to the physiological state of the yeast population. CONCLUSIONS: This study underlines the importance of minimizing B. bruxellensis populations at the end of wine ageing to reduce volatile phenols production risk once the wine in bottle. Moreover, the physiological state of the yeast seems to have an important impact on ethyl-phenols production, hence demonstrating the importance of taking into account this parameter when analysing wine spoilage risks. SIGNIFICANCE AND IMPACT OF THE STUDY: Little data exist about the survival of B. bruxellensis once the wine in bottle. This study provides information on the alteration risks encountered during wine storage in bottle and reveals the importance of carrying on further studies to increase the knowledge on B. bruxellensis physiology.

In-vacuum optical isolation changes by heating in a Faraday isolator.

We describe a model evaluating changes in the optical isolation of a Faraday isolator when passing from air to vacuum in terms of different thermal effects in the crystal. The changes are particularly significant in the crystal thermal lensing (refraction index and thermal expansion) and in its Verdet constant and can be ascribed to the less efficient convection cooling of the magneto-optic crystal of the Faraday isolator. An isolation decrease by a factor of 10 is experimentally observed in a Faraday isolator that is used in a gravitational wave experiment (Virgo) with a 10 W input laser when going from air to vacuum. A finite element model simulation reproduces with a great accuracy the experimental data measured on Virgo and on a test bench. A first set of measurements of the thermal lensing has been used to characterize the losses of the crystal, which depend on the sample. The isolation factor measured on Virgo confirms the simulation model and the absorption losses of 0.0016 +/- 0.0002/cm for the TGG magneto-optic crystal used in the Faraday isolator.

Influence of grass-based diets on milk fatty acid composition and milk lipolytic system in Tarentaise and Montbeliarde cow breeds.

Two experiments were conducted to evaluate the effects of nature of forage on fatty acid composition and lipolytic system in cow milk to increase the nutritional quality of dairy products. Each experiment was divided into a 4-wk preexperimental and 6- or 8-wk experimental period. During the 2 preexperimental periods, 56 midlactating Montbéliarde or Tarentaise cows received a diet based on corn silage. Subsequently, in Experiment 1,40 cows were allocated into 5 groups (4 Montbéliarde and 4 Tarentaise cows per group) and assigned to dietary treatments: corn silage (87% of dry matter intake), grass silage (86%), ryegrass hay (90%), mountain natural grassland hay (87%), or a diet rich in concentrate (CONC, 65/35% concentrate/hay). In Experiment 2, 16 cows divided into 2 groups were fed during 3 or 6 wk mountain natural pasture (100%) or mountain natural grassland hay (87%). Principal component analysis was applied to describe the relationships among dairy performances, milk fatty acids (FA), and lipolytic system. The milk 18:0, cis-9-18:1, trans-11-18:1, and cis-9, trans-11-18:2 percentages were closely associated with 3-wk mountain natural pasture diet, whereas short- and medium-chain (mostly saturated) FA were associated with the CONC diet. Tarentaise milk fat contained a lower proportion (-3 to 4 g/100 g) of 16:0 and higher proportions of stearic acid and fewer markedly polyunsaturated FA than Montbéliarde milk fat. Milk lipolysis was lowest for CONC and corn silage groups. Milk from Tarentaise cows presented lower initial free FA and postmilking lipolysis. Diets given to cows, especially young grass, modified the milk content of FA with a putative nutritional effect on human health.

[Family caregivers and hereditary muscular disorders: association between burden, quality of life and mental health]. / Les aidants familiaux des personnes myopathes: liaisons entre charge de soins, qualité de vie et santé mentale.

OBJECTIVE: The analysis of caregiver difficulties seems important to define the life of the patient. The aim of the study was to evaluate the burden of perceived care, health-related quality of life, and mental health of family caregivers who care for patients with hereditary neuromuscular disease. MATERIALS AND METHOD: Fifty-nine family caregivers were investigated in the course of multidisciplinary consultations in Reims, France, between April 2002 and February 2005. Burden of perceived care, mental functioning and mental health were measured by answers to an burden interview instrument (Zarit Burden Inventory, ZBI), a health-related quality of life questionnaire (the SF-36 and General Health Questionnaire-12 items [GHQ-12]), and an instrument quantifying anxiety and depression (Hospital Anxiety and Depression scale [HAD]). The domain scores of the SF-36 were compared with those of the general population. Non-parametric correlations between scores were calculated. RESULTS: Thirty-five parents, 20 spouses, a sister, a grandmother and two friends cared for patients with hereditary myopathy. The average age of caregivers was 50+/-11 years; 81% were women. Ten percent of the caregivers had above-normal scores on the HAD scale, One-third perceived a significant reduction in health-related quality of life, and more half expressed a moderate or important burden according to their answers on the ZBI. Depression occurred in a great proportion of the caregivers, and they showed reduced health-related quality of life as compared with the general population. CONCLUSION: Taking into account these results, it appears useful to set up a specific support for family caregivers of patients with hereditary myopathy.

Influence of carbon source and surface hydrophobicity on the aggregation of the yeast Kluyveromyces bulgaricus.

Aggregation of the yeast Kluyveromyces bulgaricus is mediated by the galactose-specific lectin KbCWL1. This lectin contains hydrophobic amino acids and its activity is calcium dependent. A specific fluorescent probe, 1-anilinonaphthalene-8-sulfonic acid in the free acid form (ANS; Sigma Chemical Co., St. Louis, Missouri), was used to study the hydrophobic areas on the cellular surface of K. bulgaricus. Changes in surface hydrophobicity during the growth and aggregation of yeast cells were studied. Surface hydrophobicity increased during growth and depended on the amount of yeast cells in the culture medium. During growth, the size of the hydrophobic areas on the cell surface was measured using ANS and was found to increase with the percentage of flocculating yeasts. Our results strongly suggest that the hydrophobic areas of the cell walls of yeast cells are involved in the aggregation of K. bulgaricus.

[Increase in C-reactive protein plasma levels during diabetes in infants and young adults]. / Augmentation de la concentration plasmatique de la protéine C-réactive dans le diabète de l'enfant et de l'adulte jeune.

OBJECTIVE: To investigate whether high sensitivity C-reactive protein (hs CRP) levels are elevated in young type 1 diabetic patients and to determine the relationships with age, degree of metabolic control determined by glycated hemoglobin (HbA1c), blood lipids, and subclinical complications. METHODS: High sensitivity CRP was determined in young type 1 diabetic patients and in healthy controls. Blood lipids and HbA1c were also determined. The patients were divided into 2 groups. In group A, patients were free from subclinical complications (retinopathy, nephropathy and neuropathy) and in group B, patients had at least one subclinical complication. RESULTS: The hs CRP concentrations were significantly higher in the 126 diabetic patients (55 girls and 71 boys) than in the 52 controls (2.6+/-4mg/L vs 0.7+/-0.7mg/L; p<0.001). This difference persisted when comparing the normal subjects with the 81 patients of group A (2.0+/-3.1mg/L; p<0.01) and the 45 patients of group B (3.6+/-5.1mg/L; p<0.001). The hs CRP concentrations were significantly correlated with total cholesterol, total cholesterol/HDL-cholesterol ratio, and LDL cholesterol for the 2 groups of patients. In the patients of group A, significant correlations were observed between hs CRP and age or duration of diabetes. No correlation was observed between hs CRP levels and glycaemia, HbA1c and HDL-cholesterol in the two groups of patients. CONCLUSION: Levels of hs CRP were 3-fold greater in diabetic patients without complications than in controls and 5-fold greater in diabetic patients with subclinical complications. High sensitive CRP therefore appears to be an interesting indicator of the risk for developing complications.

Study on agglutinating factors from flocculent Saccharomyces cerevisiae strains.

The lectin-like theory suggest that yeast flocculation is mediated by an aggregating lectinic factor. In this study we isolated an agglutinating factor, which corresponds to lectin, from whole cells by treating the flocculent wild-type Saccharomyces cerevisiae NCYC 625 strain and its weakly flocculent mutant [rho degrees ] with EDTA and two non-ionic surfactants (Hecameg and HTAC). The dialysed crude extracts obtained in this way agglutinated erythrocytes and this hemagglutination was specifically inhibited by mannose and mannose derivatives. However, SDS-PAGE profiles showed that the three reagents had different effects on the yeast cells. The non-ionic surfactants appeared to be the most efficient, as their extracts possessed the highest specific agglutinating activity. The products released by the wild-type strain presented a higher specific agglutinating activity than those released by the [rho degrees ] mutant. Purification of the agglutinating factor from extracts of both strains by affinity chromatography revealed two active bands of relative mass of 26 and 47 kDa on SDS-PAGE. Mass spectrometry analysis by MALDI-TOF, identified a 26 kDa band as the triose phosphate isomerase (TPI) whereas a 47 kDa band was identical to enolase. Edman degradation showed that the N-terminal sequences of these proteins were similar to TPI and enolase, respectively. The difference in the flocculation behaviour of the two strains is due to changes in the protein composition of the cell wall and in the protein structure involved in cell-cell recognition.

Sterol and fatty acid composition of Candida lusitaniae clinical isolates.

The sterol and fatty acid compositions of four amphotericin B-resistant and of two amphotericin B-susceptible Candida lusitaniae clinical isolates were determined. A flow cytofluorometric susceptibility test (FCST) with a membrane potential-sensitive cationic dye was used as a complement to the conventional method for selecting the isolates. Compared to susceptible isolates, resistant ones showed a greatly reduced ergosterol content and changes in sterol composition, consistent with a defect in Delta8-->7 isomerase. Within each group, no correlation between the sterol or fatty acid pattern or composition and both the degree of in vitro susceptibility and FCST MIC was found.

The role of glucose in the Kluyveromyces bulgaricus flocculation phenomenon: transduction by cAMP-dependent protein kinase pathway?

Yeast flocculation appears to be dependent on several culture conditions such as nitrogen or carbon sources. In 0.2% glucose medium Kluyveromyces bulgaricus flocculation intensity is weak (10% at maximum) by comparison with flocculation in 2% glucose medium (85% maximum). Addition of glucose to K. bulgaricus in exponential growth phase in 0.2% glucose medium produced a rapid increase of the flocculation percentage during the 30 min following the addition of glucose. cAMP and 2,4-dinitrophenol showed similar effects while cAMP-dependent protein kinase (PKA) inhibitors exhibited an antagonist effect. Moreover, the induction of flocculation did not seem to imply translation of new proteins: cycloheximide had no effect, although growth was inhibited. The induction of flocculation mainly implies ATP hydrolysis for activation or secretion of galactose-specific receptors as demonstrated by treatment with NaN(3). We propose a hypothesis that involves a PKA transduction signal leading to flocculation.

Solid-phase microextraction of volatile components from natural grassland plants.

The volatile components from nine plants growing on natural grasslands in Auvergne, central France, selected for the broad qualitative and quantitative diversity of their terpenoid fractions, were analyzed by high-resolution gas-phase chromatography and mass spectrometry (HRGC-MS) after static headspace solid-phase microextraction (SHS-SPME). SHS-SPME allowed all the plant material to be analyzed under the same conditions despite its wide-ranging composition. This is not always possible with other extraction methods. Using an apolar poly(dimethylsiloxane) (PDMS) phase, numerous terpenoid hydrocarbons, together with alcohols, cyclic ethers, and esters, were extracted. Its ease of use and the high resolution of the chromatographic profiles obtained make SHS-SPME well suited to the rapid characterization of the main components of the volatile fraction of plants. Of the nine plants studied, four (Meum athamanticum, Pimpinella saxifraga, Achillea millefolium, and Thymus pulegioides) exhaled more than 60 different volatile components. Certain terpenes present in large amounts in these plants might help link dairy products to grazing pasture, thus improving food traceability.

Effect of genetic potential and level of feeding on milk protein composition.

Two groups of 15 multiparous cows in mid-lactation were used in a Latin square design experiment with 4-week experimental periods. The genetic milk protein concentration level was high in the first group and low in the second. Each group of cows was given in a random order three feeding levels that covered 85, 100 and 115% of energy requirements and 90, 110 and 125% of nitrogen requirements, respeetively. In both groups, increasing level of feeding induced a significant increase in milk yield (+ 2.4 kg/d between lowest and highest levels) and in protein concentration (+ 1.7 g/kg). The proportion of paracasein in total proteins was not altered by either genetics or nutrition. The proportion of casein in total proteins was slightly increased by 0.5 percentage points (P < 0.05) with the intermediate level of feeding. Plasmin and plasminogen activities were not significantly modified by the genetic milk concentration level. Plasmin activity significantly increased with nutrient supplementation, but only in animals of low genetic potential (+ 21% between low and high levels, P < 0.01). Casein composition was not significantly altered by the genetics or level of nutrition. Over the whole range of individual measurements taken (n = 90), the relationships between casein or paracasein and total protein concentrations were linear and very narrow (R2 = 0.92 and 0.95, respectively). The proportion of casein or paracasein in total proteins significantly decreased as plasmin activity increased.

Isolation and biochemical characterization of cell wall tight protein complex involved in self-flocculation of Kluyveromyces bulgaricus.

Flocculation of yeasts is a cell-cell aggregation phenomenon which is driven by interactions between cell wall lectins and cell wall heteropolysaccharides. In Sabouraud medium, Kluyveromyces bulgaricus was highly flocculent. Incubation of flocculent K. bulgaricus cells with EDTA or Hecameg led to extracts showing hemagglutinating and flocculating properties. Purification of the extracts by native PAGE gave two bands which allowed flocculation of deflocculated K. bulgaricus. Both bands with specific reflocculating activity were composed of five subunits, of which only three possessed weak reflocculating activity upon deflocculated yeast. The mixture of these three proteins allow the recovery of initial specific reflocculating activity of the complex. These three proteins, denoted p28, p36 and p48, presented, in their first 15 amino acids, homologies with glycolysis enzymes, i.e., 3-phosphoglycerate mutase, glyceraldehyde-3-phosphate dehydrogenase and enolase, respectively. However, no such enzymatic activity could be detected in the crude extract issued from treatment with EDTA and Hecameg of flocculent yeast cells. When yeasts had grown in glucose poor medium, flocculation was drastically affected. The EDTA and Hecameg crude extracts showed weak reflocculating activity. After PAGE, the protein complexes did not appear in the EDTA extract, but they did appear in the Hecameg crude extract. These results suggest that: (i) self-flocculation of K. bulgaricus depends on the expression of different floc-forming protein complex, (ii) these proteins are galactose specific lectins showing homologies in their primary structure with glycolysis enzymes.

An individual modelling tool for consecutive clinical mastitis during the same lactation in dairy cows: a method based on a survival model.

The high number of clinical mastitis recurring within the same lactation in dairy cows constitutes one of the factors of overdispersion in standard Poisson models. Our method, based on biological parameters, i.e., recurrence hazard in relation to udder exogenous infection (Rex) or recurrence hazard and rate in relation to endogenous infection (Ren), produced a model capable of integrating a possible change of state in the udder after clinical mastitis. This model was based on a study of the time intervals between successive clinical episodes, both types of risk being considered in the form of a distribution mixture in the survival model. The modelling tool allowed to determine the factors that specifically act on either one of the potential risks and estimated the distribution of the number of clinical mastitis per lactation, as well as the distribution of when mastitis occurs. Estimation results obtained by this method in an experimental herd were compared with those from more classical models with or without random individual effects. The distribution of the number of mastitis per lactation estimated by our method was well-fitted to the data and the method identified variation factors which were relatively standard in this type of study: lactation number, lactation stage and calving month. Prediction results obtained in another experimental herd with more recent data without parameter re-estimation demonstrated the adequacy of the model in fitting observed data. This modelling method based on biological parameters in a mixture of survival distributions was interesting to model clinical mastitis recurring within the same lactation. However in the future it will also be important to integrate the possible relationship between successive lactations and to apply this model to other types of farming systems.

Permeability of yeast cell envelope to fluorescent galactosylated telomers derived from THAM.

The work reported herein deals with the study of cellular recognition and permeability phenomena in yeasts. Various galactosylated organic telomers derived from trishydroxymethyl-aminomethane (THAM) and bearing fluorescent moieties were synthesized in order to measure their ability to cross the yeast cell envelope. Grafting fluorescent probes on the organic telomer backbone allowed us to study their specific behaviors toward the yeasts by fluorescence microscopy. Yeasts belonging to the genera Kluyveromyces and Saccharomyces were used for this study. With Saccharomyces yeast cells bearing mannose-specific lectins or lectin-like proteins, on their outer surface, all the galactosylated or nongalactosylated organic telomers passed through the cell envelope and invaded the cytoplasm. With Kluyveromyces yeast cells bearing galactose-specific lectins, the galactosylated organic telomers were blocked at the outer surface while the nongalactosylated derivatives crossed the cell envelope. Moreover, preincubation of Kluyveromyces yeasts with galactose or methylgalactose inhibited the cell surface anchorage of the organic telomers and allowed their penetration into the cytoplasm. When assays were performed on spheroplasts of both Kluyveromyces and Saccharomyces yeasts, no fixation on the surface could be observed, and all the derivatives went through the membrane and invaded the cytoplasm.