Influence de l'âge, du sexe, de la race sur l'embouche des Zébus nourris avec des sous-produits rizicoles dans le Nord Cameroun

Dans le cadre du projet Elegoua, Nord Cameroun, une étude a été faite pour analyser l'influence de l'âge, du sexe et de la race sur les résultats d'embouche de 1938 zébus. Le sexe et l'âge jouent un rôle essentiel sur les performances obtenues. Les mâles entiers et les animaux compris entre 4 et 7 ans obtiennent les meilleurs résultats. Les tests effectués entre les différentes races et croisements laissent apparaître peu de différences entre races pures. Seule la race Zébu Arabe et ses croisements obtiennent des performances significativement supérieures. L'embouche d'animaux de race M'Bororo d'un âge supérieur à 5 ans donne également de bons résultats. (Résumé d'auteur

Effects of boundary roughness on a Q-factor of whispering-gallery-mode lasing microdisk cavities

We perform numerical studies of the effect of sidewall imperfections on the resonant state broadening of the optical microdisk cavities for lasing applications. We demonstrate that even small edge roughness causes a drastic degradation of high-Q whispering gallery (WG) mode resonances reducing their Q-values by many orders of magnitude. At the same time, low-Q WG resonances are rather insensitive to the surface roughness. The results of numerical simulation obtained using the scattering matrix technique, are analyzed and explained in terms of wave reflection at a curved dielectric interface combined with the examination of Poincare surface of sections in the classical ray picture.Comment: 4 pages, 3 figure

Eleven years of malaria surveillance in a Sudanese village highlights unexpected variation in individual disease susceptibility and outbreak severity

An analysis is presented of continuous data collected over 11 years based on 1 902 600 person/days of observation on the malaria experience of the people of Daraweesh, a village in eastern Sudan. Malaria transmission is hypo-endemic: the acquisition of clinical immunity with age is not as obvious as in more holo-endemic areas and malaria remained a problem in all age groups throughout the study. However, this population, who are of Fulani origin, showed a distinctly variable level of disease susceptibility. Thirty-two percent of the village never reported malaria symptoms or required malaria treatment while others experienced up to 8 clinical episodes over the 11 years of observation. Malaria incidence was clearly influenced by drought but much less obviously by rainfall. To what extent outbreak patterns are explicable in terms of anopheline factors, and to human immune factors, remains an interesting question for malaria modelling in this, and in other low transmission zones, such as the burgeoning urban areas of modern Africa

Developing a service user informed intervention to improve participation and ability to perform daily activities in primary Sjögren’s syndrome: a mixed-methods study protocol

Introduction: A significant proportion of patients with primary Sjögren’s syndrome (PSS) is functionally impaired and experience difficulties participating in various aspects of everyday life. There is currently no evidence of efficacy for non-pharmacological interventions aimed specifically at supporting the patients with PSS to improve their participation and ability to perform daily activities. This paper describes a research protocol for a mixed-methods study to develop an intervention to improve these outcomes. The protocol follows the Medical Research Council framework for complex interventions. Methods and analysis: We will use group concept mapping with the patients, adults who live with them and healthcare professionals to identify factors which prevent people with PSS from participating in daily life and performing daily activities. The factors will be prioritised by participants for importance and feasibility and will inform an intervention to be delivered within a National Health Service (NHS) setting. Evidence-based intervention techniques will be identified for the prioritised factors and combined into a deliverable intervention package. Key stakeholders will comment on the intervention content and mode of delivery through focus groups, and the data will be used to refine the intervention. The acceptability and feasibility of the refined intervention will be evaluated in a future study. Ethics and dissemination: The study has been approved by an NHS Research Ethics Committee, REC Reference: 13/NI/0190. The findings of this study will be disseminated in peer-reviewed journals and through presentation at national and international conferences. Trial registration number: UKCRN Study ID: 15939

Chronic Plasmodium falciparum infections in an area of low intensity malaria transmission in the Sudan

Chronic Plasmodium falciparum malaria infections in a Sudanese village, in an area of seasonal and unstable malaria transmission, were monitored and genetically characterized to study the influence of persistent infection on the immunology and epidemiology of low endemicity malaria. During the October-December malaria season of 1996, 51 individuals out of a population of 420 had confirmed and treated P. falciparum malaria in the village of Daraweesh in eastern Sudan. In a cross-sectional survey carried out in December 1996, an additional 6 individuals were found to harbour a microscopically negative but polymerase chain reaction (PCR)-positive P. falciparum infection. On 1 January 1997, a cohort of 43 individuals aged from 9 to 53, recruited from this group of recently malaria-infected individuals agreed to donate fortnightly blood samples for the next 9 months, the first 6 of which constitute the long Sudanese dry season when transmission falls to undetectable levels. Each blood sample was tested for the presence of persistent malaria infection by microscopy and PCR. Parasite-positive samples were genotyped using PCR assays that detect allelic polymorphism at the MSP-1, MSP-2 and GLURP marker gene loci. Of 43 individuals 16 were found to maintain chronic P. falciparum infections which were continuously genetically characterized

Plasmodium falciparum Erythrocyte Membrane Protein 1 Diversity in Seven Genomes – Divide and Conquer

The var gene encoded hyper-variable Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) family mediates cytoadhesion of infected erythrocytes to human endothelium. Antibodies blocking cytoadhesion are important mediators of malaria immunity acquired by endemic populations. The development of a PfEMP1 based vaccine mimicking natural acquired immunity depends on a thorough understanding of the evolved PfEMP1 diversity, balancing antigenic variation against conserved receptor binding affinities. This study redefines and reclassifies the domains of PfEMP1 from seven genomes. Analysis of domains in 399 different PfEMP1 sequences allowed identification of several novel domain classes, and a high degree of PfEMP1 domain compositional order, including conserved domain cassettes not always associated with the established group A-E division of PfEMP1. A novel iterative homology block (HB) detection method was applied, allowing identification of 628 conserved minimal PfEMP1 building blocks, describing on average 83% of a PfEMP1 sequence. Using the HBs, similarities between domain classes were determined, and Duffy binding-like (DBL) domain subclasses were found in many cases to be hybrids of major domain classes. Related to this, a recombination hotspot was uncovered between DBL subdomains S2 and S3. The VarDom server is introduced, from which information on domain classes and homology blocks can be retrieved, and new sequences can be classified. Several conserved sequence elements were found, including: (1) residues conserved in all DBL domains predicted to interact and hold together the three DBL subdomains, (2) potential integrin binding sites in DBLα domains, (3) an acylation motif conserved in group A var genes suggesting N-terminal N-myristoylation, (4) PfEMP1 inter-domain regions proposed to be elastic disordered structures, and (5) several conserved predicted phosphorylation sites. Ideally, this comprehensive categorization of PfEMP1 will provide a platform for future studies on var/PfEMP1 expression and function

Suppression of Pdx-1 perturbs proinsulin processing, insulin secretion and GLP-1 signalling in INS-1 cells

Aims/hypothesis: Mutations in genes encoding HNF-4α, HNF-1α and IPF-1/Pdx-1 are associated with, respectively, MODY subtypes-1, -3 and -4. Impaired glucose-stimulated insulin secretion is the common primary defect of these monogenic forms of diabetes. A regulatory circuit between these three transcription factors has also been suggested. We aimed to explore how Pdx-1 regulates beta cell function and gene expression patterns. Methods: We studied two previously established INS-1 stable cell lines permitting inducible expression of, respectively, Pdx-1 and its dominant-negative mutant. We used HPLC for insulin processing, adenovirally encoded aequorin for cytosolic [Ca2+], and transient transfection of human growth hormone or patch-clamp capacitance recordings to monitor exocytosis. Results: Induction of DN-Pdx-1 resulted in defective glucose-stimulated and K+-depolarisation-induced insulin secretion in INS-1 cells, while overexpression of Pdx-1 had no effect. We found that DN-Pdx-1 caused down-regulation of fibroblast growth factor receptor 1 (FGFR1), and consequently prohormone convertases (PC-1/3 and -2). As a result, DN-Pdx-1 severely impaired proinsulin processing. In addition, induction of Pdx-1 suppressed the expression of glucagon-like peptide 1 receptor (GLP-1R), which resulted in marked reduction of both basal and GLP-1 agonist exendin-4-stimulated cellular cAMP levels. Induction of DN-Pdx-1 did not affect glucokinase activity, glycolysis, mitochondrial metabolism or ATP generation. The K+-induced cytosolic [Ca2+] rise and Ca2+-evoked exocytosis (membrane capacitance) were not abrogated. Conclusions/interpretation: The severely impaired proinsulin processing combined with decreased GLP-1R expression and cellular cAMP content, rather than metabolic defects or altered exocytosis, may contribute to the beta cell dysfunction induced by Pdx-1 deficienc

Seasonal variation in agglutination of Plasmodium falciparum-infected erythrocytes

Abstract. Agglutination and rosette formation are in vitro characteristics of Plasmodium falciparum–infected erythrocytes, which have been associated with host protective immune responses and also with parasite virulence. The present study was carried out in an area of seasonal and unstable malaria transmission in eastern Sudan. Plasma samples were obtained before, during, and after the transmission season from a volunteer cohort of 64 individuals seven years of age and older. These plasmas were assayed for their ability to agglutinate cultured parasitized eryth-rocytes originally obtained from acute malaria infection samples taken from five of the cohort members. Our data show that the capacity of donor plasma samples to agglutinate parasitized cells depended largely on the time of sampling relative to the transmission season, at least within this epidemiologic setting. Thus, although less than half of the pretransmission season samples could agglutinate any of the five lines of cultured parasites, all post-transmission season samples could agglutinate at least one of the parasite lines, with 74 % agglutinating two or more lines. This increase in the agglutination capacity of individual plasma samples after the transmission season occurred essentially regardless of whether an individual had experienced a clinical malaria attack during the transmission season. The study thus confirms the acquisition of agglutinating antibodies following episodes of clinical malaria, but also dem-onstrates that such acquisition can take place in the absence of disease, presumably as a consequence of subclinica

Hypothyroidism in rats decreases peripheral glucose utilisation, a defect partially corrected by central leptin infusion

Aims/hypothesis: The aims of this work were to determine the effect of hypothyroidism on insulin-stimulated glucose turnover and to unravel the potential mechanisms involved in such an effect. Methods: Hypothyroidism was induced by administration of propylthiouracil, with partial T4 substitution. Euglycaemic-hyperinsulinaemic clamps, associated with the labelled 2-deoxy-d-glucose technique for measuring tissue-specific glucose utilisation, were used. To assess a possible involvement of leptin in the modulation of glucose metabolism by hypothyroidism, leptin was infused intracerebroventricularly for 6 days. A group of leptin-infused rats was treated with rT3 to determine a potential role of T3 in mediating the leptin effects. Results: Compared with euthyroid rats, hypothyroid animals exhibited decreased overall glucose turnover and decreased glucose utilisation indices in skeletal muscle and adipose tissue. Leptinaemia in hypothyroid rats was lower while resistin mRNA expression in adipose tissue was higher than in euthyroid animals. Intracerebroventricular leptin infusion in hypothyroid rats partially restored overall, muscle and adipose tissue insulin-stimulated glucose utilisation and improved the reduced glycaemic response observed during insulin tolerance tests. The leptin effects were due neither to the observed increase in plasma T3 levels nor to changes in the high adipose tissue resistin expression of hypothyroid rats. The administration of leptin to hypothyroid animals was accompanied by increased expression of muscle and adipose tissue carnitine palmitoyl transferases, decreased plasma NEFA levels and reduced muscle triglyceride content. Conclusions/interpretation: Hypothyroidism is characterised by decreased insulin responsiveness, partly mediated by an exaggerated glucose-fatty acid cycle that is partly alleviated by intracerebroventricular leptin administratio