IL-10-driven immunoglobulin production by B lymphocytes from IgA-deficient individuals correlates to infection proneness

In search for a possible explanation of the phenotypic heterogeneity in IgA deficiency, we studied the function of B cells from IgA-deficient (IgAd) individuals. Two groups of IgAd individuals, one frequently infected and one clinically apparently healthy, as well as normal controls, were studied. Peripheral blood mononuclear cells (PBMC) and B cells from IgAd individuals and controls were cultured with Staphylococcus aureus Cowan I strain and with anti-CD40 MoAb presented on the CD32-transfected fibroblast cell line in the presence of IL-10. In this experimental system PBMC and B cells from the infection-prone IgAd individuals produced only minute amounts of IgA. In contrast, PBMC and B cells from healthy IgAd subjects secreted significantly more IgA1 and IgA2 in comparison with infection-prone IgAd patients (P < 0.05). These data suggest that the abnormalities of B cell differentiation in IgAd could be of heterogeneous origin. Thus, whereas in healthy IgAd subjects IgA production may be efficiently up-regulated in vitro by addition of IL-10 to CD40-activated B cell culture, the corresponding B cell differentiation does not occur in infection-prone IgAd patients. These observations provide a conceptual framework for phenotypic heterogeneity in IgAd subjects.     

Comparison of two highly automated DNA extraction systems for quantifying Epstein-Barr virus in whole blood

BACKGROUND: Optimal automated molecular methods are needed to monitor Epstein-Barr virus (EBV) infections in transplant recipients. OBJECTIVES: To compare the extraction of EBV DNA from whole blood using the COBAS Ampliprep and the MagNA Pure instruments (Roche) for quantifying EBV DNA by real-time PCR. STUDY DESIGN: EBV DNA content was determined on clinical samples extracted by both systems. RESULTS: The detection limit was 2.16log(10)copies/mL using the COBAS Ampliprep extraction system. Specificity was 100% and we saw no cross-contamination. Extraction was linear from 2.60 to 5.60log(10)copies/mL. The intra-assay variation was 1.91% for 3.60, 2% for 4.60 and 4.51% for 5.60log(10)copies/mL; inter-assay variation was 4.88%. Sixty-six samples were tested: 26 were positive and 28 were negative by both methods. One sample was MagNA Pure positive/COBAS Ampliprep negative (virus load 3.15log(10)copies/mL) and 10 samples were MagNA Pure negative/COBAS Ampliprep positive (virus loads from 1.59 to 3.51log(10)copies/mL) (P<0.0001). Both methods gave similar quantitative results (average difference 0.07log(10)copies/mL) which were well correlated (r=0.73, P<0.001). CONCLUSIONS: The COBAS Ampliprep extraction system is comparable to the MagNA Pure and offers a high reliability for extracting EBV DNA from whole blood.     

Characterization of MgNd2 alloy for potential applications in bioresorbable implantable devices

The aim of this study is to investigate and demonstrate the mechanical and corrosive characteristics of the neodymium-containing magnesium alloy MgNd2 (Nd2), which can be used as a resorbable implant material, especially in the field of stenting applications. To determine the mechanical characteristics of Nd2, tensile and compression tests were initially carried out in the hot extruded state. Here a unique elongation ratio (～30%) of the alloy could be observed. Subsequent T5 and T6 heat treatments were arranged to reveal their effect on the alloy's strengths and elongation values. The general degradation behaviour of Nd2 in a 0.9% NaCl solution was investigated by means of polarization curves and hydrogen evolution. In addition to this, by using various in vivo parameters, a corrosion environment was established to determine the alloy's degradation in vitro. Here, the mass loss per day in (MgF(2) and Bioglass)-coated and uncoated states and the corresponding maximum forces resulting from subsequent three-point bending tests revealed slow and steady corrosion behaviour. The cell viability and proliferation tests carried out on L-929 and MSC-P5 cells also showed good results. The mechanical and corrosive characteristics determined, as well as the in vitro test results obtained within the scope of this study, led to the development and successful in vivo testing of an MgF(2)-coated Nd2 mucosa stent which was introduced as an appropriate resorbable application.     

Membrane permeability, a pivotal function involved in antibiotic resistance and virulence in Enterobacter aerogenes clinical isolates

Imipenem-susceptible E. aerogenes isolates exhibiting extended spectrum β-lactamases, target mutations and a basal efflux expression, were identified in five patients. After imipenem treatment, imipenem-intermediate susceptible (IMI-I) or resistant (IMI-R) isolates emerged in these patients. Alteration in porin synthesis and increase in efflux expression were observed in the IMI-I isolates whereas complete loss of the porins, LPS alteration and efflux overexpression were observed in the IMI-R isolates. Bacterial virulence of the strains was investigated by the Caenorhabditis elegans model. The IMI-R isolates were shown to be significantly less virulent than the IMI-susceptible or IMI-I isolates. The pleiotropic membrane alteration and its associated fitness burden exhibited by E. aerogenes isolates influence their antibiotic resistance and their virulence behaviour. These findings highlight the balance between the low permeability-related resistance and virulence and their relationships with the treatment of resistant pathogens.     

Detection of anti-HLA antibodies by solid-phase assay in kidney transplantation: friend or foe?

Pre-formed and de novo anti-human leukocyte antigen (HLA) antibodies induce antibody-mediated rejection and are also involved in mechanisms leading to chronic graft nephropathy. The detection of anti-HLA antibodies by solid-phase assay (SPA) has revolutionized the management of immunized patients before and after kidney transplantation. Characterized by high sensitivity and specificity, the clinical relevance of anti-HLA antibodies by SPA has to be clarified. The presence of donor-specific antibody at the epitope level, their titer, and the use of different crossmatch technologies could help to determine which of the anti-HLA antibodies are friends and which are foes in kidney transplantation. In this review, we summarize the current state of the art on this debated topic, and give clinical guidelines for the management of antibody detection pre- and post-transplantation, based on these evidences and our own clinical expertise.     

Effects of nitrous oxide on dopamine release in the rat nucleus accumbens and expectation of reward

Recently we have shown that nitrous oxide (N2O) was able to block the expression of morphine-induced conditioned place preference (CPP) in mice. Because dopamine (DA) has also been associated with the positive place conditioning we hypothesize that exposure to N2O would be significantly associated with a modification of extracellular level of DA. Unbiased place conditioning method was used for mice and rats. Levels of DA, in the nucleus accumbens (Nac), in awake and freely moving rats during positive place conditioning after morphine chronic treatment has been measured by microdialysis. Expression of morphine-induced CPP was totally abolished in mice and rats exposed to N2O. Results of animals placed in the morphine-paired compartment showed a 75% increase in the extracellular levels of DA, which was blocked by exposure of animals to N2O. In conclusion we showed the capacity of N2O to block the expression of morphine-induced CPP in mice and in rats. Then we demonstrated an increase of DA extracellular level in the Nac when animals were placed in the morphine-paired compartment and these increase of DA level was blocked by N2O.     

The use in routine of mass spectrometry in a hospital microbiology laboratory

Objectives

Matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) has recently been introduced in diagnostic microbiology laboratories for the identification of microorganisms. The mass fingerprint obtained by analyzing the ribosomal proteins and proteins associated with membranes is compared to spectra and superspectra of database. Microbiological Laboratory of Mulhouse acquired this system 1 year ago.

Method

The MALDI-TOF MS analyses of all strains were performed on Axima^® (Shimadzu), data analysis with Saramis^® software (Anagnostec) and integration with SirWeb^® software (I2A society).

Results

Rapidly, laboratory technicians and biologists are able to turn the system after a few days of training. The data prospectively gathered in the present study demonstrated that MALDI-TOF mass spectrometry identification is an efficient method included fastidious bacteria. Exactly 98.8 % of 10,000 isolates were identified in genus and species levels. Use of identification techniques was seldom necessary for a few clinical relevant isolates. The database is in constant evolution. The superspectra contain characteristic signals of genus, species allowing reliable microorganism identifications with high confidence.

Conclusion

In conclusion, our results show that MALDI-TOF MS is a fast and reliable technique for identification of most bacterial strains routinely isolated in a clinical microbiology. Identification and susceptibility testing with a single cell colony are more often possible. The simple tests, such as Gram staining and oxidase and catalase tests are usually performed in our laboratory.     

Macrophage migration inhibitory factor gene influences the risk of developing tuberculosis in northwestern Colombian population

Macrophage migration inhibitory factor (MIF) is a pleiotropic cytokine that regulates innate and adaptative immunity responses against pathogens. The MIF gene, at 22q11.2, is polymorphic. Functional promoter variants in the MIF gene influence susceptibility to inflammatory diseases in Caucasians and Africans. An association study was carried out to examine the influence of MIF-173 single nucleotide polymorphism and the MIF-794 microsatellite on the susceptibility to develop human tuberculosis (TB) in a well-defined Latin-American population. To this purpose, 230 northwestern Colombian patients with pulmonary TB, negative for human immunodeficiency virus infection, and 235 matched healthy individuals stratified by the tuberculin skin test were examined. Multivariate analysis showed that MIF-173C allele was associated with disease (odds ratio = 1.64, 95% confidence interval 1.07-2.52) in a dominant pattern. No allele in the MIF-794 CATT microsatellite was associated with risk of TB. These results indicate that MIF gene influences the risk of developing TB in the studied population.     

Factors and consequences of conversion in laparoscopic sigmoidectomy for diverticular disease

BACKGROUND: The disadvantages of laparoscopic elective sigmoidectomy for diverticular disease include the risk of conversion to open operation and longer operative time. The aim of this study was to analyse the causes and consequences of conversion in 168 consecutive patients who underwent a laparoscopically assisted colectomy between January 1994 and June 2001. METHODS: Data were collected prospectively to analyse the causes and consequences of conversion to open surgery in terms of postoperative morbidity and patient recovery. RESULTS: Postoperative mortality, morbidity, conversion and reoperation rates were zero, 21.4 per cent (n = 36), 14.3 per cent (n = 24) and 3.0 per cent (n = 5) respectively. The reasons for conversion were presence of intraperitoneal adhesions and/or inflammatory pseudotumour (n = 21), an intraoperative diagnosis of sigmoid cancer (n = 1), hypercapnia (n = 1) and abdominal bleeding (n = 1). Three preoperative factors were associated with a significant higher risk of conversion: surgical expertise, the presence of sigmoid stenosis or fistula, and the severity of diverticulitis on pathological examination. Morbidity was no different between laparoscopic sigmoidectomy (30 of 144; 20.8 per cent) and converted procedures (six of 24; 25.0 per cent). Open conversion was associated with a longer operative time and significantly delayed patient recovery and hospital discharge. CONCLUSION: Surgical experience and severe diverticular disease are predictive factors for conversion in laparoscopic elective sigmoidectomy. Even if necessary, conversion does not increase the morbidity rate.     

Self expanding metallic stent in the management of malignant colonic obstruction

INTRODUCTION: Fifteen to thirty percent of colonic cancers are diagnosed at acute colic obstruction stage. In this situation surgery is associated with a high morbi-mortality. The self-expandable metallic stents (SEM) have two objectives: (a) resolution of the obstructive to allow secondary planified radical surgical procedure; (b) palliative in the event of advanced disease. PATIENTS AND METHODS: From May 2001 to December 2002, 11 patients, mean age 75 +/- 8 years, presenting with acute colic obstruction were initially treated by SEM placed by endoscopy. Four patients were classified score ASA 4. Ten patients had a colonic cancer, and a patient presented a peritoneal carcinomatosis from an ovarian carcinoma. Overall five patients had a carcinomatosis. Stenosis, mean length 4 +/- 3 cm, were located on the left colon. In five patients the SEM was proposed as a palliative treatment. RESULTS: Successfully placement of SEM was obtained in 10 (91%) patient without perforation. Three complications (bleeding, reobstruction, migration) were observed. Clinical success (colonic decompression within 96 h without endoscopic or surgical reintervention) was observed in nine out of ten (90%) patients. Six patients had a SEM with curative attempt allowing (i) colonic resection (9 +/- 2 days) without stomy (one postoperative death) in five patients; (ii) a colo-colic derivation for diffuse carcinomatosis discovered peroperatively. A diverting colostomy was carried out in two of the four patients (j6, j30) (reobstruction, migration) for whom the SEM had been proposed as palliative treatment. CONCLUSIONS: This study confirms that SEM and surgery are not competitive but complementary techniques. When the SEM is placed with curative attempt, it allows resolution of the obstructive syndrome and secondary planified radical surgical procedure under better conditions. The results observed in the palliative SEM group suggested to reconsider this indication.