Effective stiffening of DNA due to nematic ordering causes DNA molecules packed in phage capsids to preferentially form torus knots.

Observation that DNA molecules in bacteriophage capsids preferentially form torus type of knots provided a sensitive gauge to evaluate various models of DNA arrangement in phage heads. Only models resulting in a preponderance of torus knots could be considered as close to reality. Recent studies revealed that experimentally observed enrichment of torus knots can be qualitatively reproduced in numerical simulations that include a potential inducing nematic arrangement of tightly packed DNA molecules within phage capsids. Here, we investigate what aspects of the nematic arrangement are crucial for inducing formation of torus knots. Our results indicate that the effective stiffening of DNA by the nematic arrangement not only promotes knotting in general but is also the decisive factor in promoting formation of DNA torus knots in phage capsids.

Prenatal diagnosis of facial clefts : evaluation of a specialised counseling

Résumé: Questions étudiées / principes: Le diagnostic prénatal des fentes faciales et palatines a soulevé maintes questions concernant la meilleure manière d'informer les parents et d'offrir une aide appropriée durant les semaines de grossesse restant, afin de faire de la naissance une expérience positive. Le conseil prénatal diffère selon la personne qui en est responsable et ses connaissances concernant les aspects pratiques des soins ainsi que l'impact de cette malformation sur la qualité de vie de l'enfant. Le but de cette étude est d'évaluer nos techniques actuelles et de les modifier de façon appropriée. Méthodes: 29 couples ayant bénéficié d'un diagnostic prénatal ont été priés de répondre rétrospectivement à un questionnaire. L'histoire obstétrique personnelle ainsi que l'histoire familiale, le déroulement des évènements, la qualité de l'information fournie et leurs impressions à la naissance ont été considérées. Résultats: Les parents utilisent de multiples sources d'information: l'obstétricien, le conseil du chirurgien pédiatrique au sein de I « équipe fente », les groupes de soutien de parents et Internet. 93% des parents se sont sentis bien préparés à la naissance de leur enfant, autant psychologiquement que concernant les aspects pratiques des soins. 54% ont été soulagés de voir leur enfant moins affecté qu'ils ne l'imaginaient. Finalement, 96% considèrent que le diagnostic prénatal est un bénéfice. Conclusion: Une information de base devrait être apportée rapidement après l'ultrason confirmant le diagnostic, suivie de discussions techniques progressivement plus détaillées durant le temps de grossesse restant. Summary: Questions under study / principles: Prenatal diagnosis of cleft lip and palate has raised many questions concerning the best way to inform the parents and offer appropriate support during the remaining pregnancy to help prepare a positive birth experience. Prenatal counseling differs according to whose is responsible and that person's knowledge of practical aspects of care and the impact of the malformation on the child's quality of life. The aim of the study was to evaluate our current techniques and modify them when appropriate. Methods: 29 couples having experienced prenatal diagnosis were asked to respond retrospectively to a questionnaire. Personal obstetric and family history, timing and quality of information provided and their impressions at birth were considered. Results: The parents used several sources of information: the obstetrician, the counsel by the cleft team surgeon, the parents support groups and Internet. 93% of the parents felt well prepared for the birth of their child psychologically and concerning practical aspects of care. 54% felt relieved that their child was less affected than imagined. 96% considered prenatal diagnosis a benefit. Conclusion: Basic information should be provided soon after ultrasound confirmation, followed by progressively more detailed technical discussions over the remaining pregnancy.

Ultrastructure of the membrane attack complex of complement: detection of the tetramolecular C9-polymerizing complex C5b-8.

The ultrastructure of the membrane attack complex (MAC) of complement had been described as representing a hollow cylinder of defined dimensions that is composed of the proteins C5b, C6, C7, C8, and C9. After the characteristic cylindrical structure was identified as polymerized C9 [poly(C9)], the question arose as to the ultrastructural identity and topology of the C9-polymerizing complex C5b-8. An electron microscopic analysis of isolated MAC revealed an asymmetry of individual complexes with respect to their length. Whereas the length of one boundary (+/- SEM) was always 16 +/- 1 nm, the length of the other varied between 16 and 32 nm. In contrast, poly(C9), formed spontaneously from isolated C9, had a uniform tubule length (+/- SEM) of 16 +/- 1 nm. On examination of MAC-phospholipid vesicle complexes, an elongated structure was detected that was closely associated with the poly(C9) tubule and that extended 16-18 nm beyond the torus of the tubule and 28-30 nm above the membrane surface. The width of this structure varied depending on its two-dimensional projection in the electron microscope. By using biotinyl C5b-6 in the formation of the MAC and avidin-coated colloidal gold particles for the ultrastructural analysis, this heretofore unrecognized subunit of the MAC could be identified as the tetramolecular C5b-8 complex. Identification also was achieved by using anti-C5 Fab-coated colloidal gold particles. A similar elongated structure of 25 nm length (above the surface of the membrane) was observed on single C5b-8-vesicle complexes. It is concluded that the C5b-8 complex, which catalyzes poly(C9) formation, constitutes a structure of discrete morphology that remains as such identifiable in the fully assembled MAC, in which it is closely associated with the poly(C9) tubule.

Geometry and physics of catenanes applied to the study of DNA replication.

The concept of ideal geometric configurations was recently applied to the classification and characterization of various knots. Different knots in their ideal form (i.e., the one requiring the shortest length of a constant-diameter tube to form a given knot) were shown to have an overall compactness proportional to the time-averaged compactness of thermally agitated knotted polymers forming corresponding knots. This was useful for predicting the relative speed of electrophoretic migration of different DNA knots. Here we characterize the ideal geometric configurations of catenanes (called links by mathematicians), i.e., closed curves in space that are topologically linked to each other. We demonstrate that the ideal configurations of different catenanes show interrelations very similar to those observed in the ideal configurations of knots. By analyzing literature data on electrophoretic separations of the torus-type of DNA catenanes with increasing complexity, we observed that their electrophoretic migration is roughly proportional to the overall compactness of ideal representations of the corresponding catenanes. This correlation does not apply, however, to electrophoretic migration of certain replication intermediates, believed up to now to represent the simplest torus-type catenanes. We propose, therefore, that freshly replicated circular DNA molecules, in addition to forming regular catenanes, may also form hemicatenanes.

Influence of the primary cleft palate closure on the future need for orthognathic surgery in unilateral cleft lip and palate patients

RESUME : Introduction : L'objectif de cette étude est de déterminer l'influence de la dissection du palais lors de la chirurgie primaire et le type de chirurgie orthognathique requise chez les patients porteurs d'une séquelle de fente labio-maxillo-palatine unilatérale complète Méthode : Cette revue porte sur 58 enfants nés avec une fente labio-maxillo-palatine complète unilatérale et traités entre 1994 et 2008 à Page approprié pour une chirurgie orthognathique. C'est une étude rétrospective longitudinale mixte. Les patients avec des syndromes ou anomalies associées ont été exclus. Tous les patients ont été traités parle même orthodontiste et par la même équipe chirurgicale. Les enfants sont divisés en deux groupes; le premier comprend les patients avec une chirurgie primaire du palais conventionnelle, avec un décollement extensif de la fibro-muqueuse palatine. Le deuxième groupe comprend les patients opérés selon le protocole de Malek. Le palais mou est fermé a |'âge de trois mois, le palais dur à |'âge de six mois, avec un décollement minimal de la tibro-muqueuse palatine. Les radiographies du crâne de profil ainsi que les données chirurgicales ont été comparées. Résultats: La nécessité d'une chirurgie orthognathique est plus élevée dans le premier groupe par rapport au deuxième (60% versus 47,8%). Concernant le type de chirurgie orthognathique réalisé, des ostéotomies Lefort I en deux ou trois pièces ou des ostéotomies bi-maxillaires ont aussi été plus fréquentes dans le premier groupe Conclusion : La chirurgie primaire du palais selon le protocole de Malek améliore le pronostic des patients avec une fente labio-maxillo-palatine. Avec un décollement minimal de la fibro-muqueuse palatine, le nombre d'interventions de chirurgie orthognathique a été diminué. Lorsque ces opérations étaient néanmoins indiquées, elles étaient simplifiées.

Chicken BAFF--a highly conserved cytokine that mediates B cell survival.

Members of the tumor necrosis factor (TNF) family play key roles in the regulation of inflammation, immune responses and tissue homeostasis. Here we describe the identification of the chicken homologue of mammalian B cell activating factor of the TNF family (BAFF/BLyS). By searching a chicken EST database we identified two overlapping cDNA clones that code for the entire open reading frame of chicken BAFF (chBAFF), which contains a predicted transmembrane domain and a putative furin protease cleavage site like its mammalian counterparts. The amino acid identity between soluble chicken and human BAFF is 76%, considerably higher than for most other known cytokines. The chBAFF gene is most strongly expressed in the bursa of Fabricius. Soluble recombinant chBAFF produced by human 293T cells interacted with the mammalian cell-surface receptors TACI, BCMA and BAFF-R. It bound to chicken B cells, but not to other lymphocytes, and it promoted the survival of splenic chicken B cells in culture. Furthermore, bacterially expressed chBAFF induced the selective expansion of B cells in the spleen and cecal tonsils when administered to young chicks. Our results suggest that like its mammalian counterpart, chBAFF plays an important role in survival and/or proliferation of chicken B cells.

Spatial analysis of erythrocyte membrane fluctuations by digital holographic microscopy.

Red blood cell (RBC) membrane fluctuations provide important insights into cell states. We present a spatial analysis of red blood cell membrane fluctuations by using digital holographic microscopy (DHM). This interferometric and dye-free technique, possessing nanometric axial and microsecond temporal sensitivities enables to measure cell membrane fluctuations (CMF) on the whole cell surface. DHM acquisition is combined with a model which allows extracting the membrane fluctuation amplitude, while taking into account cell membrane topology. Uneven distribution of CMF amplitudes over the RBC surface is observed, showing maximal values in a ring corresponding to the highest points on the RBC torus as well as in some scattered areas in the inner region of the RBC. CMF amplitudes of 35.9+/-8.9 nm and 4.7+/-0.5 nm (averaged over the cell surface) were determined for normal and ethanol-fixed RBCs, respectively.

A recombinant rubella virus E1 glycoprotein as a rubella vaccine candidate.

A recombinant rubella virus E1 (rE1) glycoprotein was produced and some of its chemical and immunological features were characterized. Two animal models were then used to establish that the rE1 glycoprotein and rubella virus particles shared antigenic and immunogenic properties. In the first one, sera from rE1 glycoprotein-immunized BALB/c mice neutralized in vitro rubella virus infection. In the second model, severe combined immune deficient (SCID) mice implanted with tonsil fragments from rubella immune donors and immunized with rE1 glycoprotein produced human anti-rubella virus antibodies. Altogether, these results showed that immunization with rE1 glycoprotein elicited neutralizing anti-rubella virus antibodies. This study thus indicated that the rE1 glycoprotein could constitute a non-replicating rubella vaccine.

BAFF binds to the tumor necrosis factor receptor-like molecule B cell maturation antigen and is important for maintaining the peripheral B cell population.

The tumor necrosis factor (TNF) family member B cell activating factor (BAFF) binds B cells and enhances B cell receptor-triggered proliferation. We find that B cell maturation antigen (BCMA), a predicted member of the TNF receptor family expressed primarily in mature B cells, is a receptor for BAFF. Although BCMA was previously localized to the Golgi apparatus, BCMA was found to be expressed on the surface of transfected cells and tonsillar B cells. A soluble form of BCMA, which inhibited the binding of BAFF to a B cell line, induced a dramatic decrease in the number of peripheral B cells when administered in vivo. Moreover, culturing splenic cells in the presence of BAFF increased survival of a percentage of the B cells. These results are consistent with a role for BAFF in maintaining homeostasis of the B cell population.