Pneumonia due to Bordetella bronchiseptica in a cystic fibrosis patient: 16S rRNA sequencing for diagnosis confirmation

Bordetella bronchiseptica was identified as an unusual etiologic agent of pulmonary recurrent exacerbations and pneumonia in a cystic fibrosis (CF) patient by utilizing a 16S rRNA molecular kit in our hospital's clinical laboratory. This method appears to be a useful approach for identifying new emerging CF pathogens when discrepancies exist between phenotypical tests.     

Evidence for a glycerol pathway through aquaporin 1 (CHIP28) channels

Permeabilities to glycerol and small non-electrolytes of three Aquaporin 1 CHIP (AQP1) water channels were measured in AQP1 cRNA-injected Xenopus laevis oocytes and in human AQP1 channels reconstituted in proteoliposomes. By an osmotic swelling assay, significant increases of ethylene glycol, glycerol and 1,3-propanediol apparent permeability coefficients (P_solutes) were found in oocytes expressing human, rat and frog AQP1. p-Chloromercuribenzene sulphonate (PCMBS) and CuSO₄ inhibited, by 95% and 58% respectively, apparent glycerol permeability (P _gly) in oocytes expressing human AQP1. pCMBS inhibition was reversed by -mercaptoethanol and CuSO₄ inhibition was partly reversed by the Cu²⁺-binding peptide Gly-Gly-His. Tritiated glycerol uptakes confirmed the augmented P _gly value of AQP1 cRNA-injected oocytes. In contrast, no increases of urea, meso-erythritol, D- or L-threitol, xylitol and mannitol uptakes were detected. Stopped-flow light scattering experiments performed with human AQP1 proteoliposomes also revealed a much greater increase of P _gly than did those with protein-free liposomes; the initial rate of proteoliposomes also swelling was inhibited by 96.2% with HgCl₂ and by 72.5% with CuSO₄. In AQP1 cRNA-injected oocytes and in proteoliposomes, the value of the glycerol reflection coefficient was 0.74–0.80, indicating that water and glycerol share the same pathway. All these results provide strong evidence that water and certain small solutes permeate the AQP1 channels expressed at the surface of X. laevis oocytes or reconstituted in proteoliposomes. The urea exclusion suggests that the selectivity of the AQP1 channels not only depends on the size of the solutes but probably also on their flexibility and their ability to form H-bonds.     

Model of bicarbonate secretion by resting frog stomach fundus mucosa I. Transepithelial measurements

In the present in vitro experiments on gastric fundus mucosa of Rana esculenta we try to define the mechanism of alkaline secretion that is observed in summer frogs in the resting stomach (blockage of HCl secretion by ranitidine, 10^–5 mol/l). The transepithelial voltage and the rate of alkalinization (ASR) of an unbuffered gastric lumen perfusate was measured as a function of serosal (and mucosal) fluid composition. ASR was high (0.88±S.E. 0.09 Eq·cm^–2·h^–1, n=11) during serosal bath perfusion with HCO₃ ^–-Ringer solution, decreased slightly to 0.50±0.07 Eq·cm^–2·h^–1 (n=6) in HCO₃ ^–-free HEPES-buffered Ringer solution of the same pH, and decreased to approximately 20% when carbonic anhydrase was inhibited by acetazolamide. While replacement of mucosal or serosal Cl^– did not — within 1 h — significantly alter ASR, replacement of serosal Na⁺ in the presence or absence of HCO₃ ^– strongly reduced ASR, and a similar reduction was observed after serosal application of the anion transport inhibitor DIDS (4,4-diisomiocyanatostilbene-2,2-disulphonate, 2·10^–4 mol/l), the metabolic poison rotenone (10^–5 mol/l), the uncoupler dinitrophenol (10^–4 mol/l), and the Na⁺ pump inhibitor ouabain (10^–4 mol/l), while serosal amiloride (10^–4 mol/l) had no effect. These data can be accounted for by a model of alkaline secretion that consists of basolateral HCO₃ ^– uptake from the serosal fluid into the cell via a DIDS-inhibitable Na⁺(HCO₃ ^–)_n-cotransporter and HCO₃ ^– secretion from the cell to the gastric lumen via an anionic conductance pathway. Microelectrode experiments on oxyntopeptic cells reported in the subsequent paper suggest that these cells may also be involved in the resting state alkaline secretion.     

Hepatitis C virus (HCV) genotypes in the Caribbean island of Martinique: evidence for a large radiation of HCV-2 and for a recent introduction from Europe of HCV-4

Molecular epidemiological studies of hepatitis C virus (HCV) in the Caribbean may help to specify the origin and spread of HCV infection. Indeed, the Caribbean population is intermixed from European and African origins and geographically close to the American continent. We characterized HCV genotypes in the Caribbean island of Martinique. HCV genotypes were analyzed by sequencing or reverse hybridization in the 5' noncoding region (5'NC) in 250 HCV-monoinfected and 85 HCV-human immunodeficiency virus (HIV)-coinfected patients. In addition, sequencing in the nonstructural 5B (NS5B) gene was required to determine the subtype or to perform phylogenetic analysis in selected samples. Genotypes 1 to 6 were found, respectively, in 84.4, 6.8, 5.2, 2.8, 0.4, and 0.4% of 250 HCV-monoinfected patients and in 71.7, 7.1, 15.3, 5.9, 0, and 0% of 85 HCV-HIV-coinfected patients. HCV-1b was found in 66.4% of the HCV-monoinfected patients and was associated with blood transfusion, whereas HCV-1a was detected in 41.2% of the HCV-HIV-coinfected patients and was associated with intravenous drug use (IVDU). The HCV-3 strains belonged to subtype 3a and were linked to IVDU. Phylogenetic analyses were focused on HCV-2 and HCV-4, which are common in Africa. Two opposite patterns were evidenced. NS5B sequences from 19 HCV-2 isolates were affiliated with many different subtypes described either in Europe or in West Africa, suggesting an ancient radiation. In contrast, seven of the nine HCV-4 NS5B sequences ranged within HCV-4a and HCV-4d clusters spreading in continental France by the IVDU route. Epidemiological data demonstrate the recent introduction of HCV-4a and -4d subtypes into the Caribbean.     

Evaluation of the association of nine Helicobacter pylori virulence factors with strains involved in low-grade gastric mucosa-associated lymphoid tissue lymphoma

Helicobacter pylori has been associated with the development of two malignant diseases: gastric adenocarcinoma and gastric mucosa-associated lymphoid tissue (MALT) lymphoma. Although the cag pathogenicity island, especially the cagA gene, has been linked with adenocarcinoma, few data concerning H. pylori pathogenic factors involved in low-grade gastric MALT lymphoma are available. The goal of this study was to analyze the prevalence of and correlation between genes coding for seven H. pylori virulence factors (cagA, cagE, vacA, iceA, babA, hopQ, and oipA) and two novel adhesins (sabA and hopZ) by comparing a collection of 43 H. pylori strains isolated from patients with low-grade gastric MALT lymphoma to 39 strains isolated from age-matched patients with gastritis only. Our results show that taken individually, none of the nine genes tested can be considered associated with MALT strains and allow us to conclude that MALT pathogenesis is not linked with more proinflammatory H. pylori strains. We demonstrated that in patients infected with strains harboring the iceA1 allele, sabA functional status, and hopZ "off" status, the odds of developing a MALT lymphoma were 10 times higher. However, the low prevalence of such strains (10 of 43 MALT strains) renders this triple association a low-sensitivity marker for MALT strains. Our data confirmed that H. pylori virulence factors are correlated with one another. If the involvement of H. pylori in MALT lymphoma is well established, the pathomechanism by which gastric lymphoma occurs remains to be identified.     

Lipopolysaccharide contamination of beta-lactoglobulin affects the immune response against intraperitoneally and orally administered antigen

BACKGROUND: Microbial components in the environment are potent activators of the immune system with capacity to shift the active immune response towards priming of Th1 and/or Th2 cells. Lipopolysaccharide (LPS), a cell-wall component of Gram-negative bacteria, is extensively present in food products like cow's milk. It is not well established, however, how this presence of LPS affects oral tolerance induction. METHODS: We studied the effect of LPS contamination in a commercial preparation of the cow milk protein beta-lactoglobulin (beta-LG) on antigen-specific immune responses. IgG1/IgG2a production upon intraperitoneal immunization without adjuvant was measured, and oral tolerance induction against beta-LG after administration of either an aqueous solution or water-in-oil (w/o) emulsion of beta-LG was evaluated. RESULTS: LPS contamination of beta-LG provoked a beta-LG-specific IgG2a response, as well as an enhanced beta-LG-specific IgG1 response upon intraperitoneal immunization. Oral tolerance induction to beta-LG was induced by aqueous solutions of beta-LG with and without LPS administration. Conversely, oral administration of w/o-emulsified beta-LG prevented oral tolerance to beta-LG only when the beta-LG was contaminated with LPS. CONCLUSIONS: LPS contamination of an aqueous protein solution does not affect oral tolerance induction, whereas LPS present in emulsion prevents oral tolerance induction towards the food protein.     

Detection of circulating Aspergillus fumigatus galactomannan: value and limits of the Platelia test for diagnosing invasive aspergillosis

The effectiveness of galactomannan detection with the Platelia test was evaluated in a prospective study of 3,327 sera from 807 patients. The specificity was 99.6% (748 of 751 cases). For the groups of patients with proven and probable invasive aspergillosis, the sensitivity was 50.0% (17 of 34 cases). The disappointing sensitivity associated with the presence of rare false-positive cases underlines the limits of this test.     

Electrophysiological investigation of microdissected gastric glands of bullfrog II. Basolateral membrane properties in the presence of histamine

Following the technical approach described in the preceding publication we have investigated if, and how, stimulation of gastric HCl secretion affects the basolateral ion transport properties of oxyntopeptic cells of Rana catesbeiana stomach. To this end microdissected gastric glands were punctured with conventional or H⁺-sensitive glass microelectrodes and the effects of changing bath ion concentrations on the cell membrane potential (V _b) and cell pH (pH_i) were determined. Except for a transient alkalinization, histamine (0.5 mmol/l) did not significantly affect V _b or pH_i. The latter averaged 7.18±0.03 (mean±SEM, n=5) under resting conditions (0.1 mmol/l cimetidine) and 7.21±0.07 (n=5) in the presence of histamine. In addition, neither the initial velocity nor the final steady-state value of the cell alkalinization following a 101 reduction of bath Cl^– concentration changed in the presence of histamine, and the same holds true for the cell acidification following a 101 reduction of bath HCO₃ ^– concentration. These observations indicate that the basolateral Cl^–/HCO₃ ^– exchanger was not stimulated by histamine, and that no other base transporters were activated. By contrast, the V _b response to elevation of bath K ⁺ concentration decreased, and so did the initial depolarizing V _b response to bath Cl^– substitution, while the secondary hyperpolarizing response increased. The latter observations are compatible with the notion that stimulation by histamine reduced a pH-insensitive part of the basolateral K⁺ conductance and reduced also the basolateral Cl^– conductance.     

The common functional C(-159)T polymorphism within the promoter region of the lipopolysaccharide receptor CD14 is not associated with sepsis development or mortality

Sepsis is characterised by a systemic inflammatory response to bacterial products during infection, which interestingly both in humans and animal models is gender associated with a higher susceptibility of males than females. The CD14 receptor is involved in activation of cells by lipopolysaccharides released from Gram-negative bacteria and, as recently shown, also by products of Gram-positive bacteria (e.g., peptidoglycans and lipoteichoic acid). The functional relevance of a C(-159)T CD14 polymorphism recently has been shown based on correlation of the T allele to higher plasma levels of soluble CD14, and higher membrane expression on monocytes. We, therefore, now analysed this CD14 polymorphism in 204 patients with severe sepsis and 247 controls. No significant difference of allele frequencies was observed between sepsis patients and controls neither for males nor females. Mortality also was not associated with the polymorphism studied. This may suggest that other mechanisms for lipopolysaccharide recognition, such as the recently described Toll-like receptors are important for inflammatory cell activation in sepsis.