In vitro triggering of somatic mutation in human naive B cells

During T cell-dependent immune response, germinal center B cells accumulate somatic mutations in their Ig V(D)J genes and give rise to affinity-selected B cells. We tested several culture conditions for triggering somatic mutation in human tonsillar naive slgD+CD23+ cells after cross-linking their membrane Igs. CD40 activation, in the presence of exogenous cytokines (IL-2, IL-4, and IL-10), induced proliferation and isotype switch without somatic mutation. In contrast, after coculture with anti-CD3-activated cloned T cells, somatic mutation accumulated in a fraction of naive B cells. Mutations included shared as well as independent events in clonally related sequences, allowing reconstitution of genealogic trees generated in vitro. Naive tonsillar B cells sorted for slgD expression can be induced to mutate their Ig V(H) gene upon coculture with activated T cells, thereby providing a model to study somatic hypermutation in vitro.     

Evaluating the reaction of actual compositions of concrete with respect to alkali-aggregate reactions preliminary testing at 110°C and 150°C

Different curing methods at 110°C and 150°C were tested on concrete prisms of various compositions in order to develop a rapid expansion test to evaluate the risl of AAR in actual concrete compositions. While no significant expansion occurred at 110°C (in water or water vapour), we obtained expansion values in the range 0–0.35% for concrete prisms cured at 150°C in water or in alkaline solution during 3–5 weeks. For both curing methods at 150°C, the highest expansion values are obtained for potentially reactive aggregates and high alkali levels in the concrete, whereas the lowest expansions correspond to the concrete mixes containing only non-reactive aggregates or having a total alkali content of less than 2.5 kg m⁻³. However, alkaline treatment accounts better for the effectiveness of mineral admixtures and, in general, for the reactivity of the concrete compositions, than curing in water. From the correlations obtained with data at 38°C or 60°C and 100% RH after 12 and 4 months, respectively, alkaline curing for 3 weeks at 150°C shows a reasonable potential for predicting accurately the influence of the total alkali content, nature of the aggregates, water/cement ratio and effectiveness of mineral admixtures on concrete expansion.

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Resume La réactivité potentielle des granulats vis à vis des alcalins du béton a fait l'objet de travaux nombreux portant sur des méthodes cccélérées de dépistage des granulats. Cependant, les essais visant à évaleur le risque associé à une composition réelle de béton sont appelés également à connaitre un développement rapide. Des travaux précurseurs ont été menés au Canada, au Royaume Uni, au Japon et en France. Nos travaux ont porté sur des méthodes d'expansion sur prismes de béton 7×7×28 cm de compositions variées. 12 ciments Portland, 19 sables, 20 graviers, ainsi que 11 ajouts pouzzolaniques et divers adjuvants ont été utilisés pour ces combinaisons. Les éprouvettes ont été soumises à des traitements tels que bain de vapeur à 110°C ou 150°C, immersion dans l'eau à 110°C ou 150°C, ou immersion en solution alcaline à 150°C, et cela pendant des durées allant jusqu'à 8 semaines. Parallèlement, des mesures d'expansion après conservation de prismes dans des conditions conventionnelles (38°C et 60°C en milieu saturé d'humidité) étaient réalisées. Les gonflements obtenus après plusieurs semaines de conservation à 110°C se sont révélés faibles quelle que soit la réactivité supposée des compositions de béton (présence de granulats réactifs, niveau élevé d'alcalins dans le béton). Les traitements à 150°C, que ce soit dans l'eau ou en solution alcaline, conduisent à des expansions de 0,00 à 0,35% en trois semaines. Les valeurs mesurées sont liées à la réactivité (ou la non réactivité) suspectée des bétons étudiés: présence de granulats très réactifs (respectivement non réactifs), teneur élevée (respectivement faible) en alcalins totaux dans le béton. Par contre, s'agissant de certains bétons, notamment à ajouts siliceux, le traitement dans l'eau à 150°C ne produit pas les résultats escomptés. En conséquence, les résultats d'expansion provoquée par ont été corrélés aux mesures de gonflement après conservation à 38°C pendant un an et plus d'une part, et à 60°C pendant 4 mois d'autre part. Les corrélations sont jugées satisfaisantes pour la plus grande partie des compositions testées, à, l'exception de certaines formules contenant des fumées de silice ou de la silice micronisée. Toutefois, la méthode proposée rend bien compte de l'influence vis à vis du gonflement de la teneur en alcalins totaux du béton, de la présence de granulats pouvant présenter un effet de pessimum, et des proportions des constituants tels que eau et ciment.

     

Texture segmentation using pyramidal Gabor functions and self-organising feature maps

This paper presents texture segmentation realised with image treatment methods and an artificial neural network model. Gabor oriented filters are used to extract frequential texture features and Self-Organising Feature Maps are used to group and interpolate these features. In order to decrease the number of filters, we use a pyramidal multiresolution method of image representation. We intend to build an architecture inspired by the early stages of the visual cortex, while making local frequential analysis of the images, which must be able to segment different textured images.     

Reactive energy measurement using frequency controlled analog-to-pulse-rate converter

Contents This paper analyzes a problem of phase shifting and deseribes a novel method for electronic reactive energy measurement. The proposed measurement structure, composed of an integrator as a phase shifting circuit and a frequency controlled analog-to-pulse-rate converter, provides for the measurement completely in accordance with IEC definition of reactive energy, which is performed with simple but high performance metering device.

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Die Blindverbrauchsmessung anhand eines netzsynchronisierten Analog-Frequenz-Wandlers

Übersicht In diesem Artikel wird das Problem der Phasenverschiebung analysiert und eine neue Meßmethode für elektronische Blindverbrauschsmessung aufgezeigt. Die vorgeschlagene Strucktur, bestehend aus einem Integrator als Phasenschieber und netzkontrolliertem Analog-Frequenz-Wandler, ermöglicht die Verwirklichung eines einfachen aber präzisen Elektrizitätszählers zur Messung der Blindenergie, dessen Arbeitsprinzip mit den IEC Empfehlungen vollkommen übereinstimmt.

     

Estimates by computer simulation of genetic distances from comparisons of RNAse A mismatch cleavage patterns

The RNAse A mismatch cleavage method was used to analyze genomic variability in RNA and DNA systems. However, there is no method which relates the digestion patterns observed to the extent of genetic variation. Here we report computer simulations which provide a simple estimator of genetic distances from the comparison of RNAse A digestion patterns. The results show that the number of non-shared fragments is proportional to the number of mutations between each pair of sequences compared. This prediction is supported by the comparison of the RNAse A mismatch patterns and the nucleotide sequences of a set of influenza A (H3N2) hemagglutinin genes. The procedure allows a quantitative and reliable use of the RNAse A mismatch cleavage method.     

Cross-sectional study of the isokinetic muscle trunk strength among school children

Our surveys have shown lifetime prevalence of L.BP. over 30% among schoolchildren. The purpose of this study was to evaluate the relationship between back and isokinetic trunk strength, anthropometric parameters, and sports activities. One hundred and seventeen healthy children aged 10-16 years were included. All these volunteers had semi-structured interview, anthropometric and dynamic strength measurements. Lifetime prevalence of back pain was 44.5% and point prevalence was 13%. In this cross-sectional study, anthropometric and strength profiles were significantly related to age and gender. Non specific low back pain was not correlated to trunk muscle strength and/or sports activities.     

Role of specific instances in controlling a dynamic system.

This article examines the claim that the learning of a dynamic control task is mediated by a lookup table consisting of previously successful trials on the task. Consistent with the predictions of a lookup table, in 2 experiments participants tended to give the same response to situations in which they had previously been successful rather than unsuccessful. Further, in both experiments, participants' knowledge did not generalize to new dissimilar situations, unless the dynamic control task was governed by a highly salient rule. A version of G. Logan's (1988) instance theory, which assumes that participants store each successful response as a separate instance linking the situation to the response, was able to quantitatively match a range of measures of participants' performance with 1 free parameter, except in the case in which the control task was governed by a salient rule. In a complementary way, an alternative rule-based model could only match participants' performance when the control task was governed by a highly salient rule. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A mouse mutant strain highly resistant to methyl beta-carboline-3-carboxylate-induced seizures

It is believed that DOPA-negative melanocytes in the outer root sheath of the human hair follicle are activated, become identifiable by DOPA staining, and migrate into the epidermis during the repigmenting phase of vitiligo. These cells are difficult to identify, however, and otherwise have not been characterized. These cells are readily identified by immunofluorescence, immunohistochemistry, and immunoelectronmicroscopy using the antibodies NKI/beteb and A4F11, which recognize premelanosome-related antigens. The majority of the outer root sheath melanocytes were found in the mid to the upper portion of the hair follicle. Double staining revealed that these cells were distinct from HLA-DR-bearing dendritic cells. Further immunohistochemical investigation using alpha-PEP-7, alpha-PEP-1, or TMH-1 and alpha-PEP-8 antibodies revealed that outer root sheath melanocytes cannot be identified by antibodies to tyrosinase, TRP-1, or TRP-2, respectively. These cells also did not react with HMB45 antibody, which recognizes a melanosome-associated cytoplasmic antigen. We believe that the inactive outer root sheath melanocytes contain some of the early structural proteins but not any of the enzymatic proteins necessary for melanogenesis. Therefore, activation is the process whereby outer root sheath melanocytes acquire all of the structural and enzymatic proteins necessary for melanogenesis.     

Utility of Albicans ID plate for rapid identification of Candida albicans in clinical samples. Rapid identification of Candida albicans

A clinical study was carried out in an attempt to assess the efficacy of a newly designed electric toothbrush compared to a conventional manual toothbrush using the American Dental Association's protocol for evaluating toothbrushes. An Oral-B 35 manual toothbrush, which served as the control, was compared to the Plaq & White125 electric toothbrush. Examinations were performed by two calibrated examiners at baseline, day 15 and day 30. Examinations included the gingival index, plaque index and bleeding index. Mean indices were calculated and compared between the two brushes using the repeated measures multiple analysis of variance. No statistically significant differences between the mean indices on the three examination days were observed following the use of the manual or the electric toothbrushes. The results of this study demonstrate that the electric toothbrush was numerically more effective than the manual toothbrush in reducing supragingival plaque levels, either before or after brushing, at each examination date compared to baseline plaque values. However, this difference was not statistically significant. This and other findings concluded that the Plaq & White toothbrush is comparable to the control ADA-accepted toothbrush.