Dipstick Test for Rapid Diagnosis of Shigella dysenteriae 1 in Bacterial Cultures and Its Potential Use on Stool Samples

International audienceBACKGROUND: We describe a test for rapid detection of S. dysenteriae 1 in bacterial cultures and in stools, at the bedside of patients. METHODOLOGY/PRINCIPAL FINDINGS: The test is based on the detection of S. dysenteriae 1 lipopolysaccharide (LPS) using serotype 1-specific monoclonal antibodies coupled to gold particles and displayed on a one-step immunochromatographic dipstick. A concentration as low as 15 ng/ml of LPS was detected in distilled water and in reconstituted stools in 10 minutes. In distilled water and in reconstituted stools, an unequivocal positive reaction was obtained with 1.6×10⁶ CFU/ml and 4.9×10⁶ CFU/ml of S. dysenteriae 1, respectively. Optimal conditions to read the test have been determined to limit the risk of ambiguous results due to appearance of a faint yellow test band in some negative samples. The specificity was 100% when tested with a battery of Shigella and unrelated strains in culture. When tested on 328 clinical samples in India, Vietnam, Senegal and France by laboratory technicians and in Democratic Republic of Congo by a field technician, the specificity (312/316) was 98.7% (95% CI:96.6-99.6%) and the sensitivity (11/12) was 91.7% (95% CI:59.8-99.6%). Stool cultures and the immunochromatographic test showed concordant results in 98.4 % of cases (323/328) in comparative studies. Positive and negative predictive values were 73.3% (95% CI:44.8-91.1%) and 99.7% (95% CI:98-100%). CONCLUSION: The initial findings presented here for a simple dipstick-based test to diagnose S. dysenteriae 1 demonstrates its promising potential to become a powerful tool for case management and epidemiological surveys

Analysis of the putative role of CR1 in Alzheimer’s disease: Genetic association, expression and function

Chronic activation of the complement system and induced inflammation are associated with neuropathology in Alzheimer's disease (AD). Recent large genome wide association studies (GWAS) have identified single nucleotide polymorphisms (SNPs) in the C3b/C4b receptor (CR1 or CD35) that are associated with late onset AD. Here, anti-CR1 antibodies (Abs) directed against different epitopes of the receptor, were used to localize CR1 in brain, and relative binding affinities of the CR1 ligands, C1q and C3b, were assessed by ELISA. Most Abs tested stained red blood cells in blood vessels but showed no staining in brain parenchyma. However, two monoclonal anti-CR1 Abs labeled astrocytes in all of the cases tested, and this reactivity was preabsorbed by purified recombinant human CR1. Human brain-derived astrocyte cultures were also reactive with both mAbs. The amount of astrocyte staining varied among the samples, but no consistent difference was conferred by diagnosis or the GWAS-identified SNPs rs4844609 or rs6656401. Plasma levels of soluble CR1 did not correlate with diagnosis but a slight increase was observed with rs4844609 and rs6656401 SNP. There was also a modest but statistically significant increase in relative binding activity of C1q to CR1 with the rs4844609 SNP compared to CR1 without the SNP, and of C3b to CR1 in the CR1 genotypes containing the rs6656401 SNP (also associated with the larger isoform of CR1) regardless of clinical diagnosis. These results suggest that it is unlikely that astrocyte CR1 expression levels or C1q or C3b binding activity are the cause of the GWAS identified association of CR1 variants with AD. Further careful functional studies are needed to determine if the variant-dictated number of CR1 expressed on red blood cells contributes to the role of this receptor in the progression of AD, or if another mechanism is involved

Cross-Cultural Validation of the Inventory of School Motivation (ISM) in the Asian Setting: Hong Kong and the Philippines

Students’ achievement goals in school have received increasing research attention because they have been shown to be important in predicting important outcomes. As such, there has been a growing interest in measuring and comparing them across different cultural groups. However, these comparisons cannot be made until validity evidence has been attained to support the use of an instrument in the new cultural setting. In this study, we investigated the cross-cultural applicability of the Inventory of School Motivation (ISM, McInerney et al. American Educational Research Journal 34:207-236, 1997) in the Hong Kong Chinese and Philippine contexts using both within-network and between-network approaches to construct validation. The ISM measures four types of achievement goals: mastery, performance, social, and extrinsic goals. 1,406 high school students from Hong Kong (n = 697) and the Philippines (n = 709) participated. Results of the within-network test showed that the ISM had good internal consistency reliability and the confirmatory factor analysis provided support for the hypothesized four-factor model. Multigroup confirmatory factor analyses supported invariance of factor loadings across the two samples. The between-network test also indicated that these achievement goals correlated systematically with different aspects of students’ self-concepts. These findings support the applicability of the ISM among Hong Kong Chinese and Filipino students

Swallowing: Is It a Carotid Massage Equivalent Causing Syncope in Patients With Neck Masses?

Syncope associated with the act of swallowing (deglutition syncope) and syncope associated with head and neck cancers have been documented independently. We present a case of syncope precipitated by a combination of both these mechanisms. It is important to recognize the coexistence of different hemodynamically significant mechanisms leading to syncope. A 66-year-old male recently diagnosed with head and neck cancer presented with syncope associated with eating. Diagnosis was complicated because of multiple factors in this patient, which individually could have led to syncope. The patient was on beta-blocker therapy, had a neck mass, and the episodes were associated with swallowing. Our hypothesis is that all these etiologies together led to the events but not in their typical mechanisms and raises the possibility that swallowing can be considered a carotid massage equivalent in patients with neck masses not physically extending to the carotid sinus

Blended learning as a tool for work-life oriented master courses

Masters degree programmes in Finnish Universities of Applied Sciences focus strongly on students’ real life work experience and incorporate this in the approach to teaching and learning. Students on these programmes have a higher education degree and at least three years’ work experience. Typical course assignments are real development tasks for the students’ own employer and classes harness students’ diverse experience to enhance the knowledge-base of the course. These courses are proving very popular, but management in practice of such courses (particularly with increasing numbers) is proving problematic. This paper reports findings from a pilot study in which a blended learning approach was used for the delivery of such a course. In this case “blended” refers not just to the mixture of online and face-to-face learning opportunities, but to the mixing of teacher-led instruction with co-creation of knowledge by course participants. Data collected from the study indicate a high degree of satisfaction from both students and staff and point to the particular appropriateness of the technologies used for this interpretation of blended learning. Lack of technology skills is identified as a potential issue requiring further consideration