PubMed Health⌕ Search

Biomedical subjects

C Louis

Publications and source records attributed to C Louis.

At least 19 recordsLinked to original sources
PubMed2006

Evolution of Mesobuthus gibbosus (Brullé, 1832) (Scorpiones: Buthidae) in the northeastern Mediterranean region.

Sequence data derived from two mitochondrial markers, 16S rRNA and COI genes, were used to infer the evolutionary history of 47 insular and mainland populations covering most of the distributional range of the northeastern Mediterranean scorpion species Mesobuthus gibbosus. Based on the estimated divergence times of Mesobuthus lineages, the temporal frame of the genus differentiation in the northeastern Mediterranean region is placed in middle Miocene (15 million years ago). The biogeographic affinities of M. gibbosus populations point towards a mainly vicariant pattern of differentiation of the species which is consistent with the geological events that transformed the Aegean region during the period from 12 to 5 million years ago. M. gibbosus is an old northeastern Mediterranean species that has retained valuable bits of genetic information, reflecting some of the oldest vicariant events that have occurred in the area. Most importantly, the history witnessed by M. gibbosus has not been obscured by more recent palaeoevents of the region. Therefore, the case of M. gibbosus is in favour of a taxon-oriented 'perception' of the natural history of a given area.

Animals↗
PubMed2005

Simulations of the mean chord length of a multi-element TEPC irradiated by monoenergetic neutrons.

In recent years IRSN has developed tissue-equivalent proportional counters (TEPCs) for neutron monitoring. A detector with a multi-element geometry was studied for personal dosimetry purposes. The determination of the personal dose equivalent using a multi-element TEPC requires to calculate the mean chord length of the charged particles in the counter gas. This paper presents the results of the simulations using the MCNPX code and explains the influence of the gas parameters on the mean chord length and the consequences on the dose equivalent response.

Body Burden↗
PubMed2005

An Anopheles gambiae salivary gland promoter analysis in Drosophila melanogaster and Anopheles stephensi.

Regulatory regions driving gene expression in specific target organs of the African malaria vector Anopheles gambiae are of critical relevance for studies on Plasmodium-Anopheles interactions as well as to devise strategies for blocking malaria parasite development in the mosquito. In order to identify an appropriate salivary gland promoter we analysed the transactivation properties of genomic fragments located just upstream of the An. gambiae female salivary gland-specific genes AgApy and D7r4. An 800 bp fragment from the AgApy gene directed specific expression of the LacZ reporter gene in the salivary glands of transgenic Anopheles stephensi. However, expression levels were lower than expected and the transgene was expressed in the proximal-rather than in the distal-lateral lobes of female glands. Surprisingly, a promoter fragment from the D7r4 gene conferred strong tissue-specific expression in Drosophila melanogaster but only low transcription levels in transgenic An. stephensi. These results imply a certain conservation of gland-specific control elements between the fruit fly and the mosquito suggesting that an increased degree of complexity, probably connected to the evolution of haematophagy, underlies the regulation of tissue-specific expression in mosquito female salivary glands.

Animals↗
PubMed2005

Gene expression in insecticide resistant and susceptible Anopheles gambiae strains constitutively or after insecticide exposure.

A microarray containing approximately 20 000 expressed sequence tags (ESTs; 11 760 unique EST clusters) from the malaria vector, Anopheles gambiae, was used to monitor differences in global gene expression in two insecticide resistant and one susceptible strains. Statistical analysis identified 77 ESTs that were differentially transcribed among the three strains. These include the cytochrome P450 CYP314A1, over-transcribed in the DDT resistant ZAN/U strain, and many genes that belong to families not usually associated with insecticide resistance, such as peptidases, sodium/calcium exchangers and genes implicated in lipid and carbohydrate metabolism. Short-term (6 and 10 h) effects of exposure of the pyrethroid resistant RSP strain to permethrin were also detected. Several genes belonging to enzyme families already implicated in insecticide or xenobiotic detoxification were induced, including the carboxylesterase COEAE2F gene and members of the UDP-glucuronosyl transferase and nitrilase families.

Animals↗
PubMed2005

The annexin gene family in the malaria mosquito Anopheles gambiae.

Annexins belong to a class of proteins that are known to bind to, and hold together structures such as membranes. Interestingly, Anopheles gambiae (and Drosophila melanogaster) annexins bind Plasmodium ookinetes in vitro. In the malaria mosquito three genes in two cytogenetic loci on chromosome arm 2R encode annexin homologues; their expression, monitored by quantitative real-time PCR during mosquito development, as well as in various tissues, revealed little fluctuation in patterns of expression during all life stages. A different mode of transcription was observed for the three genes in the midgut in relation to the uptake of a blood meal. Immunohistochemical staining of midguts and ovaries with polyclonal anti-annexin sera reveals that the Anopheles polypeptides are present in the epithelial cells of both tissues and associated with the plasma membrane.

Amino Acid Sequence↗
PubMed2005

AnoBase: a genetic and biological database of anophelines.

AnoBase (http://www.anobase.org) is an integrated, relational database of basic biological and genetic data on anopheline species, with a particular emphasis on Anopheles gambiae. It has been designed as an information source and research support tool for the broad vector biology community. Although AnoBase is not a primary genomic database that develops and provides tools to access the genome of the malaria mosquito, it nevertheless contains several sections that offer data of genomic interest such as in situ hybridization images, an integrated gene tool and direct online access to AnoXcel, the proteomic database of An. gambiae. Moreover, AnoBase also contains information on non-gambiae mosquito species and a novel section on studies related to insecticide resistance.

Animals↗
PubMed2004

Synthesis and properties of europium-based phosphors on the nanometer scale: Eu2O3, Gd2O3:Eu, and Y2O3:Eu.

Nanocrystals of oxides containing europium as the main constituent or as a doping element in RE2O3 ( RE=Y, Gd) have been prepared by direct oxide precipitation in high-boiling polyalcohol solutions and characterized by high-resolution TEM, absorption spectroscopy, and luminescence spectroscopy. The samples obtained consisted of concentrated and colloidally stable suspensions of luminescent oxide nanoparticles with an average grain diameter in the range 2-5 nm. The nanoparticles were found to be highly crystalline despite their ultrasmall size and the low temperature of 180 degrees C applied during the synthesis. Upon UV excitation, the red luminescence relative to the 5D0-->7Fn transition within the cubic form of RE2O3 exhibits some important differences from that usually found in bulk materials.

Journal Article↗
PubMed2004

SSR181507, a putative atypical antipsychotic with dopamine D2 antagonist and 5-HT1A agonist activities: improvement of social interaction deficits induced by phencyclidine in rats.

Social behaviour is frequently impaired in schizophrenic patients, and current antipsychotics appear poorly effective in alleviating this deficit. SSR181507 is a selective dopamine D2 receptor antagonist and 5-HT1A receptor agonist [Neuropsychopharmacology 28 (2003) 2064] with an atypical antipsychotic profile and additional antidepressant/anxiolytic activities [Neuropsychopharmacology 28 (2003) 1889]. Here, we sought to assess the efficacy of SSR181507, and of reference antipsychotics and antidepressant/anxiolytics, to counteract phencyclidine (PCP)-induced social interaction deficit in rats. Pairs of unfamiliar rats were placed for 10 min each day into a dimly lit arena, during four consecutive days. On the test day (5th day), each pair was placed into the arena 30 min after i.p. treatment with PCP (or vehicle) and a challenge compound or vehicle (same for both rats, i.p. or s.c.). The time spent in social interaction was scored during 10 min. PCP (1 mg/kg) decreased social interaction time by about 35%. This effect was fully antagonized by pre-treatment with SSR181507 (1 mg/kg). In contrast, neither haloperidol (0.05 and 0.1 mg/kg) nor clozapine (0.3 and 1 mg/kg) antagonized this PCP-induced deficit. The selective 5-HT1A receptor agonist 8-OH-DPAT (0.025 and 0.05 mg/kg s.c.), but not the anxiolytic diazepam (0.75 and 1.5 mg/kg), also improved social interaction impairment in PCP-treated rats: this would indicate that the 5-HT1A receptor agonist properties of SSR181507 are responsible for the reversal of PCP-induced social deficit. These data suggest that, in addition to its atypical antipsychotic profile and antidepressant/anxiolytic activities, SSR181507 has a potential therapeutic activity in another key feature of schizophrenia poorly controlled by current antipsychotics, namely deterioration in social functioning.

Animals↗
PubMed2004

AnoXcel: an Anopheles gambiae protein database.

The proteome of the mosquito Anopheles gambiae was organized on a hyperlinked spreadsheet format containing one protein per row and several pieces of information in each column. The information for each protein ranges from the presence or absence of signal peptide indicative of secretion, presence of transmembrane domains, similarities to several databases, chromosomal location, and relatedness to other An. gambiae proteins, etc. Hosted by AnoBase (http://www.anobase.org/), the whole spreadsheet or segments of it can be downloaded or searched from http://www.anobase.org/AnoBase/Genes/Ano-Xcel by the scientist dealing with the annotation of proteome subsets such as those deriving from transcriptomes, nucleotide microarrays or high throughput mass spectrometry data.

Animals↗
PubMed2004

An insulin-like growth factor 2-derived self-antigen inducing a regulatory cytokine profile after presentation to peripheral blood mononuclear cells from DQ8+ type 1 diabetic adolescents: preliminary design of a thymus-based tolerogenic self-vaccination.

This work aims to evaluate the potential use of insulin-like growth factor 2 (IGF-2) as the dominant thymic self-antigen precursor of the insulin family in designing a tolerogenic approach to type 1 diabetes (T1D) prevention. This evaluation was primarily based on cytokine profile driven by MHC presentation of insulin and IGF-2-derived antigens to PBMC cultures derived from 16 T1D DQ8(+) adolescents. Insulin B9-23, one dominant beta-cell autoantigen, and the homologous sequence B11-25 of IGF-2 display the same affinity and fully compete for binding to DQ8, a MHC-II allele conferring major genetic susceptibility to type 1 diabetes (T1D). However, compared to insulin B9-23, presentation of IGF-2 B11-25 elicits a suppressive/regulatory cytokine profile with a higher number of IL-10-secreting cells (P < 0.05), a much higher ratio of IL-10/IFN-gamma (P < 0.01), as well as a lower number of IL-4-secreting cells (P < 0.05). Thus, with regard to T1D prevention, administration of IGF-2-derived self-antigen(s) seems to be an efficient approach that combines both antagonism for binding to a major susceptibility MHC-II allele, as well as downstream promotion of an antigen-driven tolerogenic response.

Adolescent↗
PubMed2002

[Surgical treatment of acute pancreatitic with infected necrosis by necrosectomy-pancreatostomy].

UNLABELLED: Technical modalities of surgical treatment of infected pancreatic necrosis remains controversial. The aim of this retrospective study was to assess the results of necrosectomy associated by pancreatostomy using active drainage according Mikulicz, which is currently an unusual technique. PATIENTS AND METHODS: From 1985 to 1997, 18 consecutive patients (median age = 63; range = 35-88 years) were operated on through laparotomy for infected necrosis and treated by necrosectomy combined with Mikulicz drainage. Fourteen patients were referred from another center, including 9 who had previous surgery. Necrosectomy was performed after a median delay of 22 days (1-45) after onset of pancreatitis, in all patients because of severe sepsis (including 12 patients with persisting shock) and presence at CT scan of necrotic collections containing gas bubbles (n = 15) and/or infection proven by percutaneous aspiration (n = 3). RESULTS: After the first procedure, patients underwent between 2 and 25 (median: 5) additional necrosectomies through the pancreatostomy tract. Thirteen surgical complications were observed in 8 patients: digestive fistula (n = 7), intraabdominal bleeding (n = 3), gastrointestinal haemorrhage (n = 1), colic stenosis with colectasy (n = 1). Five patients, all referred from another center, died (28%) between the 47th and the 140th day from multiorgan failure (n = 4) or gastrointestinal haemorrhage (n = 1). The median hospital stay was 109 days (26-265) including 51 in intensive care unit (1-134). The 13 surviving patients were followed during an average of 2 years (4 months-7 years). All developed an incisional hernia of the pancreatostomy tract, which was surgically treated in 6 cases. CONCLUSIONS: Necrosectomy-pancreatostomy is an appropriate treatment of acute pancreatitis with infected necrosis, despite the usual need of additional but easy necrosectomies, and the frequent occurrence of incisional hernia. Results observed in patients referred to our center suggest that earlier diagnosis of necrosis infection using percutaneous aspiration could improve the prognosis.

Adult↗
PubMed2002

[Kidney cancer in horseshoe kidney. A case report of an unexpected diagnosis].

The authors report a case of renal cell carcinoma in a horseshoe kidney and discuss diagnostic and therapeutical aspects arising from this combination. Renal carcinoid tumors and nephroblastoma seems to be more frequent in this malformation. Diagnosis of horseshoe kidney may be difficult and angiography examination is very useful to confirm renal anomaly, tumor situation, and to plan the surgical approach because vascularization vary case to case. Heminephrectomy adapted to neoplasic localisation remains the essential treatment.

Angiography↗
PubMed2002

A cluster of four D7-related genes is expressed in the salivary glands of the African malaria vector Anopheles gambiae.

Four genes expressed in the Anopheles gambiae adult female salivary glands and similar in sequence to the Aedes aegypti D7 gene were identified. The genes, called D7-related (D7r), are included in a single cluster encompassing approximately six kilobases on chromosome arm 3R. The deduced proteins contain secretory signals and they are probably injected by the mosquito into the host with the saliva during blood feeding. The region of similarity to D7 encompasses the carboxy-terminal part of the Ae. aegypti protein and the different An. gambiae D7r show a degree of similarity to each other, varying from 53% to 73%. The weak but significant similarity to members of a wide family of insect proteins, including odourant- and pheromone-binding proteins, raises the possibility that the D7r-encoded proteins may bind and/or carry small hydrophobic ligands.

Aedes↗
PubMed2001

Anopheles gambiae laminin interacts with the P25 surface protein of Plasmodium berghei ookinetes.

Laminin is a major constituent of the basal lamina surrounding the midgut of the malaria vectors that has been implicated in the development of the Plasmodium oocyst. In this report we describe the cloning of the Anopheles gambiae gene encoding the laminin gamma 1 polypeptide and follow its expression during mosquito development. To further investigate the putative role of laminin in the transmission of the malaria parasite we studied the potential binding of the P25 surface protein of Plasmodium berghei using a yeast two-hybrid system. Heterodimer formation was observed and does not require any additional protein factors since purified fusion proteins can also bind each other in vitro. Laminin gamma 1 also interacts with the paralogue of P25, namely P28, albeit more weakly, possibly explaining why the two parasite proteins can substitute for each other in deletion mutants. This represents the first direct evidence for molecular interactions between a surface protein of the Plasmodium parasite with an Anopheles protein; the strong interplay between laminin gamma 1 and P25 suggests that this pair of proteins may function as a receptor/ligand complex regulating parasite development in the mosquito vector.

Amino Acid Sequence↗
PubMed2001

Developmental variation in epidermal growth factor receptor size and localization in the malaria mosquito, Anopheles gambiae.

The AGER gene encoding the epidermal growth factor receptor (EGFR) of the malaria mosquito Anopheles gambiae was cloned and sequenced. It represents a canonical member of this family of tyrosine kinase proteins exhibiting many similarities to orthologues from other species, both on the level of genomic organization and protein structure. The mRNA can be detected throughout development. Western analysis with an antibody raised against the extracellular domain of the mosquito protein suggests developmental variation in protein size and location that may be involved in the function of EGFR in the mosquito.

Animals↗
PubMed2001

Molecular characterization of ribosomal DNA polymorphisms discriminating among chromosomal forms of Anopheles gambiae s.s.

The sequence of a 2.3 kb long DNA segment derived from the 5'-most end of the ribosomal intergenic spacer was determined in three chromosomal forms of Anopheles gambiae s.s. The analysis revealed that the sequence of the Mopti form differed from that of the Bamako and Savanna forms by a total of ten nucleotide substitutions. Using these sequence variations we set up a diagnostic polymerase chain reaction (PCR) assay to distinguish mosquitoes belonging to the three chromosomal forms, facilitating studies on the distribution and the ecology of these incipient taxa. The assay also allows to distinguish whether a given specimen could represent a heterozygote between Mopti and Savanna or Bamako.

Animals↗
PubMed2001

Beta-integrin of Anopheles gambiae: mRNA cloning and analysis of structure and expression.

We have isolated an mRNA encoding a beta integrin subunit of the malaria mosquito Anopheles gambiae. Our analysis predicts a protein that is very similar to betaPS, the fruitfly orthologue. The gene is expressed during all developmental stages and it is found in all body parts, including the midgut. Finally, the expression of the gene does not seem to be modulated during blood meals, except for a substantial increase 48 h posthaematophagy, when digestion is nearly complete.

Amino Acid Sequence↗