Evaluation and optimization of a commercial enzyme linked immunosorbent assay for detection of Chlamydophila pneumoniae IgA antibodies

<p>Abstract</p> <p>Background</p> <p>Serologic diagnosis of <it>Chlamydophila pneumoniae </it>(Cpn) infection routinely involves assays for the presence of IgG and IgM antibodies to Cpn. Although IgA antibodies to Cpn have been found to be of interest in the diagnosis of chronic infections, their significance in serological diagnosis remains unclear. The microimmunofluorescence (MIF) test is the current method for the measurement of Cpn antibodies. While commercial enzyme linked immunosorbent assays (ELISA) have been developed, they have not been fully validated. We therefore evaluated and optimized a commercial ELISA kit, the SeroCP IgA test, for the detection of Cpn IgA antibodies.</p> <p>Methods</p> <p>Serum samples from 94 patients with anti-Cpn IgG titers ≥ 256 (study group) and from 100 healthy blood donors (control group) were tested for the presence of IgA antibodies to Cpn, using our in-house MIF test and the SeroCP IgA test. Two graph receiver operating characteristic (TG-ROC) curves were created to optimize the cut off given by the manufacturer.</p> <p>Results</p> <p>The MIF and SeroCP IgA tests detected Cpn IgA antibodies in 72% and 89%, respectively, of sera from the study group, and in 9% and 35%, respectively, of sera from the control group. Using the MIF test as the reference method and the cut-off value of the ELISA test specified by the manufacturer for seropositivity and negativity, the two tests correlated in 76% of the samples, with an agreement of Ƙ = 0.54. When we applied the optimized cut-off value using TG-ROC analysis, 1.65, we observed better concordance (86%) and agreement (0.72) between the MIF and SeroCP IgA tests.</p> <p>Conclusion</p> <p>Use of TG-ROC analysis may help standardize and optimize ELISAs, which are simpler, more objective and less time consuming than the MIF test. Standardization and optimization of commercial ELISA kits may result in better performance.</p

External validation of a prediction model for estimating fat mass in children and adolescents in 19 countries: individual participant data meta-analysis

Objective To evaluate the performance of a UK based prediction model for estimating fat-free mass (and indirectly fat mass) in children and adolescents in non-UK settings. Design Individual participant data meta-analysis. Setting 19 countries. Participants 5693 children and adolescents (49.7% boys) aged 4 to 15 years with complete data on the predictors included in the UK based model (weight, height, age, sex, and ethnicity) and on the independently assessed outcome measure (fat-free mass determined by deuterium dilution assessment). Main outcome measures The outcome of the UK based prediction model was natural log transformed fat-free mass (lnFFM). Predictive performance statistics of R2, calibration slope, calibration-in-the-large, and root mean square error were assessed in each of the 19 countries and then pooled through random effects meta-analysis. Calibration plots were also derived for each country, including flexible calibration curves. Results The model showed good predictive ability in non-UK populations of children and adolescents, providing R2 values of >75% in all countries and >90% in 11 of the 19 countries, and with good calibration (ie, agreement) of observed and predicted values. Root mean square error values (on fat-free mass scale) were <4 kg in 17 of the 19 settings. Pooled values (95% confidence intervals) of R2, calibration slope, and calibration-in-the-large were 88.7% (85.9% to 91.4%), 0.98 (0.97 to 1.00), and 0.01 (−0.02 to 0.04), respectively. Heterogeneity was evident in the R2 and calibration-in-the-large values across settings, but not in the calibration slope. Model performance did not vary markedly between boys and girls, age, ethnicity, and national income groups. To further improve the accuracy of the predictions, the model equation was recalibrated for the intercept in each setting so that country specific equations are available for future use. Conclusion The UK based prediction model, which is based on readily available measures, provides predictions of childhood fat-free mass, and hence fat mass, in a range of non-UK settings that explain a large proportion of the variability in observed fat-free mass, and exhibit good calibration performance, especially after recalibration of the intercept for each population. The model demonstrates good generalisability in both low-middle income and high income populations of healthy children and adolescents aged 4-15 years

Genome-wide scan for selection signatures reveals novel insights into the adaptive capacity in local North African cattle

Natural-driven selection is supposed to have left detectable signatures on the genome of North African cattle which are often characterized by the fixation of genetic variants associated with traits under selection pressure and/or an outstanding genetic differentiation with other populations at particular loci. Here, we investigate the population genetic structure and we provide a first outline of potential selection signatures in North African cattle using single nucleotide polymorphism genotyping data. After comparing our data to African, European and indicine cattle populations, we identified 36 genomic regions using three extended haplotype homozygosity statistics and 92 outlier markers based on Bayescan test. The 13 outlier windows detected by at least two approaches, harboured genes (e.g. GH1, ACE, ASIC3, HSPH1, MVD, BCL2, HIGD2A, CBFA2T3) that may be involved in physiological adaptations required to cope with environmental stressors that are typical of the North African area such as infectious diseases, extended drought periods, scarce food supply, oxygen scarcity in the mountainous areas and high-intensity solar radiation. Our data also point to candidate genes involved in transcriptional regulation suggesting that regulatory elements had also a prominent role in North African cattle response to environmental constraints. Our study yields novel insights into the unique adaptive capacity in these endangered populations emphasizing the need for the use of whole genome sequence data to gain a better understanding of the underlying molecular mechanisms

Field evaluatin of Mediterranean fruit fly mass trapping with Tripack as alternative to malathion bait-spraying in citrus orchards

The mass trapping technique based on the use of the female-targeted attractant lure Tri-pack® as an alternative to malathion bait-spraying (control treatment) was tested in two citrus orchards in the North of Tunisia against the Mediterranean fruit fly Ceratitis capitata during 2006 and 2007. Results of mass trapping trials in 2006 and 2007 indicated that adult males Medfly captures showed reductions respect to control of 37.62% and 40.2% respectively in mandarin orange variety (Citrus reticulata) orchard compared to 36.48% and 47.29% in Washington navel orange variety (Citrus sinensis) field. Fruit damage assessment showed significant differences between the mass trapping with Tripack® and malathion bait-spraying techniques in the reduction of the percentage of fruit punctures. The percentage of punctured fruit at harvest was significantly different between the treated and the control field in 2006 and in 2007 in the mandarin orange orchard. Nevertheless, in the Washington navel orange orchard, the percentage of punctured fruit at harvest was significantly different between the treated and the control field only in 2006. Thus, results obtained from this study showed that the mass trapping technique based on the use of the female-targeted lure Tri-pack® could be involved as an appropriate strategy for the control of the Medfly and is as effective as malathion bait spraying treatment without leaving pesticide residues on fruit.Se probó en dos huertos de cítricos, en el norte de Túnez en 2006 y 2007, la técnica del trampeo masivo utilizando el atrayente de hembras Tri-Pack® contra la mosca mediterránea de la fruta, Ceratitis capitata, como alternativa a los tratamientos cebo con malatión, que constituye la forma convencional de control utilizada por los agricultores y que se utilizó como tratamiento control. En 2006 y 2007, en los ensayos de trampeo masivo, las capturas de machos adultos del insecto se redujeron respecto el control, respectivamente, un 37,62% y un 40,2% en la variedad de mandarina (Citrus reticulata) en comparación con un 36,48% y un 47,29% en la variedad de naranja Washington navel (Citrus sinensis). Al evaluar los daños en los frutos se observaron diferencias significativas entre el trampeo masivo con Tripack ® y los tratamientos cebo con malatión con una reducción de las picaduras en los frutos El porcentaje de frutos con picaduras en el momento de la cosecha fue significativamente diferente en las parcelas control y tratada en el huerto de mandarina tanto en 2006 como en 2007. Sin embargo, en el huerto de naranja Washington navel, el porcentaje de frutos con picaduras recolectados fue significativamente diferente entre el tratado y el control sólo en 2006. Por tanto, los resultados obtenidos en este estudio muestran que la técnica de trampeo masivo utilizando el atrayente de hembras Tri-Pack® podría ser una estrategia adecuada para el control de la mosca mediterránea de la fruta y es tan efectiva como el tratamiento cebo con malatión, pero sin dejar residuos de plaguicidas en la fruta

[Antimicrobial susceptibility and frequency of occurrence of clinical blood isolates in Sfax-Tunisia (1993-1998)].

&lt;p&gt;Antimicrobial susceptibility and frequency of occurrence of clinical blood isolates in Sfax-Tunisia (1993-1998). The choice of antimicrobial therapy for the treatment of bacteremia is often empirical and based on the knowledge of susceptibility profiles of the most common bacteria causing such infections. This study determines the bacterial etiology of bacteremic episodes and antimicrobial susceptibility patterns recorded at a teaching hospital, from January 1993 to December 1998. We collected 2979 strains responsible for bacteremia. Gram negative bacteria were predominant (60%). The organisms recovered most frequently were Staphylococcus aureus (18.9%), Escherichia coli (14.7%), Klebsiella pneumoniae (14%) and Pseudomonas aeruginosa (7.6%). The incidence of resistance to methicillin were 17.4% for Staphylococcus aureus and 26.8% for coagulase negative Staphylococcus. No resistance to glycopeptides was observed among the enterococci and staphylococci studied. 27.7% of enterobacteriaceae were resistant to third generation cephalosporins. Imipenem was the most active agent against gram negative bacteria. To carry out a surveillance of bacteremic episodes occurring at every hospital, it is necessary to provide valuable information which should be the basis for effective empiric therapy.&lt;/p&gt;</p

Étude de l'érosion due au phénomène d'arc dans les contacts de relais des centraux electromécaniques - Corrélation érosion-durée d'arc. Influence de la vapeur d'eau atmosphérique sur la durée d'arc

Arcing in electrical contacts of telephone switching relays and subsequent erosion has been the subject of a great deal of work. Nevertheless the problem depends on many parameters (electrical circuits, environmental, mechanical, contact shapes...), of which the knowledge is incomplete. This is the case for the contacts used in Crossbar telephone exchanges. The aim of this work is to show that erosion and arc duration on break are correlated, and to apply the results of this correlation to calculate the erosion of two Ag/Cu (90/10) contact shapes operating in ambient atmosphere (80 % relative humidity) or in ambient dried atmosphere (15 % relative humidity).Le phénomène d'arc dans les contacts des relais téléphoniques et l'érosion qui en résulte, ont été l'objet d'un grand nombre de travaux. Néanmoins, le problème dépendant de plusieurs paramètres (circuits électriques, atmosphère environnante, paramètres mécaniques, formes de contacts...), les connaissances restent encore partielles. C'est le cas pour les contacts utilisés dans les centraux téléphoniques du type Crossbar. Le but de cette étude est de montrer que l'érosion et la durée d'arc à l'ouverture sont corrélées et d'appliquer les résultats de cette corrélation pour calculer l'érosion sur deux formes différentes de paires de contacts en AgCu (90/10), fonctionnant en atmosphère ambiante 80 % d'humidité relative ou en atmosphère ambiante desséchée (15 % d'humidité relative)

Critical behavior in Fe-doped manganites La0.67Ba0.22Sr0.11Mn1−x Fe x O3 (0 ≤ x ≤ 0.2)

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Experiment, mean field theory and Monte Carlo simulations of the magnetocaloric effect in La 0.67 Ba 0.22 Sr 0.11 MnO 3 compound

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