Epidemiological study of pap genes among diarrheagenic or septicemic Escherichia coli strains producing CS31A and F17 adhesins and characterization of Pap(31A) fimbriae

The association of the pap operon with the CS31A and F17 adhesins was studied with 255 Escherichia coli strains isolated from calves, lambs, or humans with diarrhea. The three classes of PapG adhesin with different receptor binding preferences were also screened. The pap operon was associated with 50 and 36% of human strains that produced CS31A and ovine strains that produced F17, respectively. Among the bovine isolates, the pap operon was detected in 61% of the CS31A-positive isolates and 72% of the strains that produce both CS31A and F17. The class II adhesin gene was present in bovine (20%) and ovine (71%) isolates. Both class II and III adhesins were genetically associated with 36% of the human strains. The highest prevalence of the pap operon was observed among E. coli strains that produce additional adhesins involved in the binding of bacteria to intestinal cells. Among the bovine isolates, the reference strain for CS31A and F17c was found to be positive for the pap operon. Phenotypic and genotypic characterizations were undertaken. Pap(31A) appeared as fine and flexible fimbriae surrounding the bacteria but did not mediate adhesion to calf intestinal villi. Pap(31A) production was optimal with bacteria cultured on minimal growth media and repressed by addition of exogenous leucine. The deduced amino acid sequence of the PapA(31A) structural subunit showed 57 to 97% identity with the different P-related structural subunits produced by E. coli strains isolated from pigs with septicemia or humans with urinary tract infections. None of the three papG allelic variants was detected, but a homologous papG gene was present in the chromosome of strain 31A.     

Interleukin 17 modulates the immune response to vaccinia virus infection

Interleukin 17 (IL-17) is a newly identified cytokine that has a homolog in herpesvirus saimiri. We inserted murine IL-17 into vaccinia virus to study the role of IL-17 in viral infection. Vaccinia virus expressing IL-17 (vv-IL17) and its parental control virus (vv-pRB) grew to similar titers in vitro; however, vv-IL17 was more virulent in mice with a threefold lower LD(50) than for vv-pRB, and mean time to death of 2.8 days versus 4.5 days. Mice infected with vv-IL17 had higher titers of virus in the ovaries (P < 0.02) and showed a decrease in NK cell cytotoxicity (P < 0.02) on day 3 after infection. No significant difference was found in CTL activity. In addition, a significant decrease in IgG2a (P < 0.01) and increases in IgG1, IgG3, and IgA (P < 0.03) vaccinia virus-specific antibody titers were observed in mice infected with vv-IL17 versus vv-pRB, suggesting a Th-2-like response to infection. These data indicate that IL-17 modulates the immune response during virus infection.     

Protection from insulin-dependent diabetes mellitus is linked to a peptide transporter gene

HLA class II association with insulin-dependent diabetes mellitus (IDDM) is well established but is still difficult to map to a particular locus. Polymorphism of the genes coding for transporter associated with antigen processing (TAP1 and TAP2), and located in the HLA class II region, was studied in 167 IDDM patients (116 adult-onset and 51 childhood-onset patients) and 98 normal controls using oligotyping after genomic amplification. A dominant protective effect was observed for theTAP2*0201 allele [relative risk (RR)=0.3, corrected probability (pc) < 0.001]. Conversely, susceptibility to IDDM was associated with apparent homozygosity for the TAP2*0101 allele (RR=3.4, pc < 0.001). Protection was independent from but additive to the protection conferred by the DRB1*02 DQB1*0602 haplotype (RR=0.06, pc<0.05), and antagonistic to the DRB1*03 DQB1*0201 and DRB1*04 DQB 1*0302 haplotypes predisposing effect (RR=1.1, not significant), arguing in favor of an absence of linkage disequilibrium between TAP2 and HLA class II genes. This was assessed by x² analysis. TAP1 allelic distribution was not different among diabetics and controls. A significant association was observed between the presence of TAP2*0101 and that of islet cell antibodies (p < 0.05). These data suggest that the TAP2 gene, which encodes protein required for delivery of antigen peptides to class I molecules in the endoplasmic reticulum, could modulate the autoimmune response leading to β cell destruction. From a practical point of view, they make the combined screening of HLA class II and TAP2 loci a highly valuable tool in IDDM prediction.     

Pharmacokinetics of tiaprofenic acid in children after a single oral dose

Summary. Twelve healthy children in three age groups anaesthetized for minor surgery were given a single oral dose of tiaprofenic acid (3 mg · kg^–1) (TA). Seven blood samples and zero to 8 and 8 to 24 h urines were collected. TA concentrations in plasma and urine were measured by HPLC.No significant difference was found between the age groups in the kinetic parameters of TA and no correlation was found between these parameters and age; t_max=2.12h, C_max=8.78mg · l^–1, AUC_{(08 h)} 33.9mg · h · l^–1, AUC=39.3 mg · h · l^–1, t_1/2=2.35 h, V_z=0.319 l · kg^–1, CL=0.094 l · h^–1 · kg^–1. Renal clearance was 14 ml · h^–1. kg^–1. 33% of the TA dose was recovered in the 24 h urine, 48% of which was conjugated, whereas in adults, TA is only found in urine as conjugates.The apparent plasma clearance was significantly higher (56%) than in 12 healthy adults given 1.5 mg · kg^–1 TA. Volume of distribution and t_1/2 did not significantly differ between children and adults. Since no relationship has been established between plasma TA and either efficacy or toxicity, a different dose regimen cannot be recommended in 3–11 year-old children from that in adults.     

On the dynamical basis of the classification of normal galaxies

Some realistic galaxy models have been found to support discrete unstable spiral modes. Here, through the study of the relevant physical mechanisms and an extensive numerical investigation of the properties of the dominant modes in a wide class of galactic equilibria, we show how spiral structures are excited with different morphological features, depending on the properties of the equilibrium model. We identify the basic dynamical parameters and mechanisms and compare the resulting morphology of spiral modes with the actual classification of galaxies. The present study suggests a dynamical basis for the transition among various types and subclasses of normal and barred spiral galaxies.     

Liver tumours in children: diagnostic and therapeutic approach in the Tropics

Liver tumours in children are rare and their prognosis are poor. Through a cross and retrospective study, we examined the epidemiological, clinical and therapeutic aspects on a number of patients in our hospital to try and improve the management of cases. This study involved 66 children admitted to the pediatric oncology unit of University Hospital of Treichville in Abidjan between 1991 and 2007. The average age of children was 7.2 years and the sex ratio of 1.4. 42 children lived in the countryside and 52 children were from disadvantaged areas. 63.2% of children were not vaccinated against hepatitis B. The abdominal mass was the primary sign of discovery and these tumours were dominated in both their primitive and secondary forms by the Burkitt's lymphoma.     

Rhodium effects on Pt anode materials in a direct alkaline ethanol fuel cell

The development of efficient catalysts for ethanol oxidation in alkaline medium requires a synthetic approach that may prevent the surfactant molecules from being adsorbed at the catalytic sites and decreasing the electrochemical performance of the final direct ethanol fuel cell. Toward this goal, the recently reported surfactant-less Bromide Anion Exchange (BAE) method, appears as a promising route to conveniently aim at preparing PtRh alloys dispersed on carbon substrates. The catalysts prepared herein by the BAE method were characterized physicochemically to obtain structural information on the PtRh/C nanomaterials, their morphology (size and shape), and their chemical and surface composition. Electrochemical behavior and properties of these electrodes were then investigated in a half-cell before the implementation of a direct ethanol fuel cell (DEFC) in a home-made anion exchange membrane Teflon cell. The analysis of the electrolytic solution in the anodic compartment by chromatography revealed that acetate was the major reaction product and the carbonate amount increased with the Rh content in the bimetallic composition. With 2.8–3.6 nm particle sizes, the Pt₅₀Rh₅₀/C catalyst exhibited the highest activity towards the ethanol electrooxidation.

The development of efficient catalysts for ethanol oxidation in alkaline medium requires an approach that avoids surfactant molecules from being adsorbed at active sites and decreasing the electrochemical performance of the direct ethanol fuel cell.     

Cellular signaling by an agonist-activated receptor/Gs alpha fusion protein.

The consequences of agonist-dependent activation of guanine nucleotide-binding protein (G protein)-coupled receptors vary from cell to cell, depending on a complex network of regulations between components of the signaling cascade. Specific interactions between receptors, G proteins, and effectors are difficult to analyze in intact cells. Engineering of receptor-transducer fusion proteins might be an effective strategy to target cellular effectors more efficiently and specifically. As a model, we evaluated the ability of a fusion protein of beta 2-adrenergic receptor bound to the alpha subunit of adenylyl cyclase-stimulatory G protein (Gs alpha) to restore the defective activation of adenylyl cyclase in S49 cyc- cells that lack endogenous Gs alpha. The coupling between the two partners of the fusion protein was functional, and the agonist-dependent activation of the effector was more potent and more productive in transfected than in wild-type S49 cells. The covalent link between receptor and Gs alpha could thus convey an advantage over freely interacting components. Such receptor-G alpha fusion proteins may help to elucidate the complex interactions between members of signaling pathways and may also constitute a useful tool for studying the effects of single effector activation.