One-step sensing of foodborne pathogenic bacteria using a 3D paper-based device.

Managing food contamination from bacteria has been an ongoing issue in the public health and industrial fields. Enzymatic substrates possessing optical properties, e.g. fluorescence or color manifestation, are widely exploited in pathogenic/non-pathogenic bacteria culture methods. Recently, various chromogenic substrates have been utilized in the development of point-of-care diagnostic tools. Herein, four types of chromogenic substrates were exploited to develop paper-based sensors for major foodborne pathogens. We designed a compact sized three-dimensional paper device with a simple user interface. By inserting functional layers in the middle of multilayers, pre-lysis and pH regulation steps were excluded and the analysis time was subsequently reduced, while only one sample droplet was needed for the whole analysis process. After the enzymatic reactions had proceeded, target-specific colors appeared. When it was combined with enrichment, 101 cfu mL-1 of pathogens were successfully detected in 4-8 hours, while those in milk samples were readily sensed in 12 hours. The proposed bacteria sensor exhibited great advantages of low cost, portability and simple operation, while showing a respectable limit-of-detection as low as 101 cfu mL-1 and below. Significantly, we emphasize that it takes fewer steps than existing methods and provides a reduced analysis time owing to the layer functionalization.

Comparison of immunogenicity and reactogenicity of split versus subunit influenza vaccine in Korean children aged 6-35 months.

BACKGROUND: Studies comparing the immunogenicity and reactogenicity of trivalent inactivated subunit (SU) and split (SPL) vaccines in children in Asia are limited. In 2008, we assessed the safety and immunogenicity of SU and SPL influenza vaccines in Korean children aged 6-35 months. METHODS: We studied 2 non-randomized cohorts of children who received either SU or SPL vaccine in an open-label non-stratified controlled trial at 6 hospitals in Korea. We measured antibody titers with a hemagglutination-inhibition assay at baseline and 30 days after the first or second flu shot. The primary goal was the determination of vaccine immunogenicity according to the European Union Committee of Human Medicinal Products licensing criteria. RESULTS: Out of a total of 106 participants aged 6-35 months, 47 received the SPL vaccine and 59 the SU vaccine. After vaccination, 41 (87.2%), 40 (85.1%), and 33 (70.2%) of the 47 subjects in the SPL group had titers ≥ 1:40 against H1N1, H3N2, and B, respectively. In the SU group, 42 (71.2%), 34 (57.6%), and 22 (37.3%) of 59 subjects had titers ≥ 1:40 against H1N1, H3N2, and B, respectively. The post-vaccination geometric mean titers of H1N1, H3N2, and B (SPL vs SU) were 119.1, 99.8, and 61.4 vs 75.4, 51.2, and 24.1, respectively. There were no serious vaccine-related adverse events. There were no differences between the SPL and SU vaccines with respect to adverse events. CONCLUSIONS: The immunogenicity of the SPL vaccine appears to be better than that of the SU vaccine in children aged 6-35 months in Korea.

Genome-wide analysis of low-dose irradiated male Drosophila melanogaster with extended longevity.

Ionizing radiation generates oxidative stress, which is thought to be a major cause of aging. Although living organisms are constantly exposed to low levels of radiation, most studies examining the effect of radiation have focused on accelerated aging and diminished life span that result from high-dose radiation. On the other hand, several studies have suggested that low-dose radiation enhances the longevity of Drosophila melanogaster. Therefore, investigation of the biological effects of low-dose radiation could contribute to a more comprehensive understanding of the aging process. In this study, microarray and quantitative real time-PCR were used to measure genome-wide changes in transcript levels in low-dose irradiated fruit flies that showed enhanced longevity. In response to radiation, approximately 13% of the genome exhibited changes in gene expression, and a number of aging-related genes were significantly regulated. These data were compared with quantitative trait loci affecting life-span to identify candidate genes involved in enhanced longevity induced by low-dose radiation. This genome-wide survey revealed novel information about changes in transcript levels in low-dose irradiated flies and identified 39 new candidate genes for molecular markers of extended longevity induced by ionizing radiation. In addition, this study also suggests a mechanism by which low-dose radiation extends longevity.

Chronic low-dose γ-irradiation of Drosophila melanogaster larvae induces gene expression changes and enhances locomotive behavior.

Although radiation effects have been extensively studied, the biological effects of low-dose radiation (LDR) are controversial. This study investigates LDR-induced alterations in locomotive behavior and gene expression profiles of Drosophila melanogaster. We measured locomotive behavior using larval pupation height and the rapid iterative negative geotaxis (RING) assay after exposure to 0.1 Gy γ-radiation (dose rate of 16.7 mGy/h). We also observed chronic LDR effects on development (pupation and eclosion rates) and longevity (life span). To identify chronic LDR effects on gene expression, we performed whole-genome expression analysis using gene-expression microarrays, and confirmed the results using quantitative real-time PCR. The pupation height of the LDR-treated group at the first larval instar was significantly higher (∼2-fold increase in PHI value, P < 0.05). The locomotive behavior of LDR-treated male flies (∼3 - 5 weeks of age) was significantly increased by 7.7%, 29% and 138%, respectively (P < 0.01), but pupation and eclosion rates and life spans were not significantly altered. Genome-wide expression analysis identified 344 genes that were differentially expressed in irradiated larvae compared with in control larvae. We identified several genes belonging to larval behavior functional groups such as locomotion (1.1%), oxidation reduction (8.0%), and genes involved in conventional functional groups modulated by irradiation such as defense response (4.9%), and sensory and perception (2.5%). Four candidate genes were confirmed as differentially expressed genes in irradiated larvae using qRT-PCR (>2-fold change). These data suggest that LDR stimulates locomotion-related genes, and these genes can be used as potential markers for LDR.

Low-dose radiation induces Drosophila innate immunity through Toll pathway activation.

Numerous studies report that exposing certain organisms to low-dose radiation induces beneficial effects on lifespan, tumorigenesis, and immunity. By analyzing survival after bacterial infection and antimicrobial peptide gene expression in irradiated flies, we demonstrate that low-dose irradiation of Drosophila enhances innate immunity. Low-dose irradiation of flies significantly increased resistance against gram-positive and gram-negative bacterial infections, as well as expression of several antimicrobial peptide genes. Additionally, low-dose irradiation also resulted in a specific increase in expression of key proteins of the Toll signaling pathway and phosphorylated forms of p38 and JNK. These results indicate that innate immunity is activated after low-dose irradiation through Toll signaling pathway in Drosophila.