Maximal cliques structure for cocomparability graphs and applications

Il s'agit d'une recherche sur les relations entre les graphes d'intervalles et les graphes de cocomparabilitéA cocomparability graph is a graph whose complement admits a transitive orientation. An interval graph is the intersection graph of a family of intervals on the real line. In this paper we investigate the relationships between interval and cocomparabil-ity graphs. This study is motivated by recent results [5, 13] that show that for some problems, the algorithm used on interval graphs can also be used with small modifications on cocomparability graphs. Many of these algorithms are based on graph searches that preserve cocomparability orderings. First we propose a characterization of cocomparability graphs via a lattice structure on the set of their maximal cliques. Using this characterization we can prove that every maximal interval subgraph of a cocomparability graph G is also a maximal chordal subgraph of G. Although the size of this lattice of maximal cliques can be exponential in the size of the graph, it can be used as a framework to design and prove algorithms on cocomparability graphs. In particular we show that a new graph search, namely Local Maximal Neighborhood Search (LocalMNS) leads to an O(n + mlogn) time algorithm to find a maximal interval subgraph of a cocomparability graph. Similarly we propose a linear time algorithm to compute all simplicial vertices in a cocomparability graph. In both cases we improve on the current state of knowledge

European Lung Cancer Working Party. Clinical Practice Guidelines. Small Cell Lung Cancer: V. Extensive disease

The present guidelines on the management of extensive disease small cell lung cancer (SCLC) were formulated by the ELCWP in October 2007. They are designed to answer the following nine questions: 1) What is the definition of extensive disease? 2)What are the active drugs? 3) What is the best induction regimen? 4) Is there a role for maintenance chemotherapy? 5) Is there a role for dose-intensive chemotherapy? 6) Is there a role for the use of haemopoietic growth factors and stem cells support? 7) Is there a role for alternating or sequential chemotherapy? 8) Is there a role for biological treatments? 9) Is there a place for second-line chemotherapy

Remyelination after chronic spinal cord injury is associated with proliferation of endogenous adult progenitor cells after systemic administration of guanosine

Axonal demyelination is a consistent pathological sequel to chronic brain and spinal cord injuries and disorders that slows or disrupts impulse conduction, causing further functional loss. Since oligodendroglial progenitors are present in the demyelinated areas, failure of remyelination may be due to lack of sufficient proliferation and differentiation of oligodendroglial progenitors. Guanosine stimulates proliferation and differentiation of many types of cells in vitro and exerts neuroprotective effects in the central nervous system (CNS). Five weeks after chronic traumatic spinal cord injury (SCI), when there is no ongoing recovery of function, intraperitoneal administration of guanosine daily for 2 weeks enhanced functional improvement correlated with the increase in myelination in the injured cord. Emphasis was placed on analysis of oligodendrocytes and NG2-positive (NG2+) cells, an endogenous cell population that may be involved in oligodendrocyte replacement. There was an increase in cell proliferation (measured by bromodeoxyuridine staining) that was attributable to an intensification in progenitor cells (NG2+ cells) associated with an increase in mature oligodendrocytes (determined by Rip+ staining). The numbers of astroglia increased at all test times after administration of guanosine whereas microglia only increased in the later stages (14 days). Injected guanosine and its breakdown product guanine accumulated in the spinal cords; there was more guanine than guanosine detected. We conclude that functional improvement and remyelination after systemic administration of guanosine is due to the effect of guanosine/guanine on the proliferation of adult progenitor cells and their maturation into myelin-forming cells. This raises the possibility that administration of guanosine may be useful in the treatment of spinal cord injury or demyelinating diseases such as multiple sclerosis where quiescent oligodendroglial progenitors exist in demyelinated plaques

Guanosine reduces apoptosis and inflammation associated with restoration of function in rats with acute spinal cord injury

Spinal cord injury results in progressive waves of secondary injuries, cascades of noxious pathological mechanisms that substantially exacerbate the primary injury and the resultant permanent functional deficits. Secondary injuries are associated with inflammation, excessive cytokine release, and cell apoptosis. The purine nucleoside guanosine has significant trophic effects and is neuroprotective, antiapoptotic in vitro, and stimulates nerve regeneration. Therefore, we determined whether systemic administration of guanosine could protect rats from some of the secondary effects of spinal cord injury, thereby reducing neurological deficits. Systemic administration of guanosine (8 mg/kg per day, i.p.) for 14 consecutive days, starting 4 h after moderate spinal cord injury in rats, significantly improved not only motor and sensory functions, but also recovery of bladder function. These improvements were associated with reduction in the inflammatory response to injury, reduction of apoptotic cell death, increased sparing of axons, and preservation of myelin. Our data indicate that the therapeutic action of guanosine probably results from reducing inflammation resulting in the protection of axons, oligodendrocytes, and neurons and from inhibiting apoptotic cell death. These data raise the intriguing possibility that guanosine may also be able to reduce secondary pathological events and thus improve functional outcome after traumatic spinal cord injury in humans

A new LBFS-based algorithm for cocomparability graph recognition

International audienc

Étude de la co-adsorption de tensioactifs sur charbon actif dans l’eau

L’adsorption statique de quantité micromolaire de bromure de benzyldodécyldiméthylammonium (BBDDA) sur du charbon actif en poudre a été étudiée dans l’eau distillée seule, puis en présence de sels minéraux NaCl et CaCl2 et de composés organiques : le naphtol-2, le nonylphénoxyheptaéthoxyéthanol (NP8) et le dodécylétherpentaéthoxyéthanol (DE6). Les trois premiers composés ne modifient pas la capacité ultime d’adsorption du BBDDA (Γ∞ = 0,59 mmol.g–1), déterminée à partir des isothermes de Langmuir. Par contre, la co-adsorption en présence de NP8 ou de DE6 diminue fortement cette capacité ultime. L’utilisation d’un modèle montre que l’adsorption se ferait sur des sites spécifiques avec une inhibition due à la présence de l’autre composé. La détermination du potentiel zêta des suspensions de charbon a été faite sur le charbon seul (ζ = -22 mV), puis sur des suspensions de charbon contenant de 10–4 à 10–2M NaCl (ζ = -13 mV) ou 10–2M CaCl2 (ζ = -9 mV). La présence du tensioactif cationique dans tous les cas augmente la valeur du potentiel zêta vers des valeurs plus positives (-2 mV). La réduction de ce potentiel permet d’avoir une estimation de l’épaisseur de la « couche diffuse » de Debye-Hückel

The General Practitioner and Children of Separated Parents in Belgium: A Qualitative Study and its Implications

Background: Many children are experiencing their parents’ separation and General practitioners (GPs) oftenhave the responsibility to medically follow these young patients.Objectives: The goals were to identify the main difficulties GPs are confronted with when following childrenof separated (or divorced) parents and to find ways to improve the quality of these children’s continuous medicalmonitoring.Methods: Eight focus groups of GPs were organized in 2004 in the French-speaking Community of Belgium.Each meeting focused on couples separated for less than three years, with children aged 0 to 15. The debates wereanalysed with the QSR N5 software. Data saturation was obtained after four focus groups.Results: The viewpoint of GPs is: 1. Divorce affects the working conditions of GPs. 2. Conflicts between theparents cause difficulties for the GP, particularly the fact of being « exploited » by the parents. 3. All GPs do nothave the same attitude towards conflicts between the parents; only some of them will try to « manage » the conflictsto improve the child’s situation. 4. Especially in the case of conflicts, parental separation brings a risk for the child:psychological disorders, physical health problems. 5. The professional attitudes of GPs can have a positive influenceon the child’s development, including direct child-centred communication with the child. 6. Some actions, such asproducing sickness certificates or official reports of neglect, can aggravate these children’s situation, especially inthe case of conflicts between the parents.Discussion: Parental separation could be an independent risk factor for the child’s health by inducing somedifficulties of tracking in primary care medicine. If this is confirmed, in case of a family breakdown, the GP shouldadapt the practice of prevention and care, recognizing young patients as most at risk. In order to confirm the possibleimpact of family status, cohort studies must be conducted either transverse observational targeting unselectedpaediatric populations of different ages, or even better in prospective research. Given the high prevalence of parentalseparation in Belgium, the influence of these situations should be measured in terms of public health.info:eu-repo/semantics/publishe

On the power of graph searching for cocomparability graphs

International audienceIn this paper we study how graph searching on a cocomparability graph G can be used to pro- duce cocomp orderings, (i.e., orderings that are linear extensions of some transitive orientation of G) that yield simple algorithms for various intractable problems in general. Such techniques have been used to find a simple certifying algorithm for the minimum path cover problem. In particular we present a characterization of the searches that preserve cocomp orderings when used as a “+ sweep”. This allows us to present a toolbox of different graph searches and a framework to solve various problems on cocomparability graphs. We illustrate these techniques by describing a very simple certifying algorithm for the maximum independent set problem as well as a simple permutation graph recognition algorithm.Keywords: Cocomparability graphs, comparability graphs, partial orders, linear extensions, graph algorithms, classical graph searches, lexicographic depth first search (LDFS), minimum path cover problem, recognition of permutation graphs

Cloning of a xylanase gene from Streptomyces sp. EC3

info:eu-repo/semantics/publishe