The relationship between classical item characteristics and item response time on computer-based testing

Purpose This study investigated the relationship between the item response time (iRT) and classic item analysis indicators obtained from computer-based test (CBT) results and deduce students’ problem-solving behavior using the relationship. Methods We retrospectively analyzed the results of the Comprehensive Basic Medical Sciences Examination conducted for 5 years by a CBT system in Dankook University College of Medicine. iRT is defined as the time spent to answer the question. The discrimination index and the difficulty level were used to analyze the items using classical test theory (CTT). The relationship of iRT and the CTT were investigated using a correlation analysis. An analysis of variance was performed to identify the difference between iRT and difficulty level. A regression analysis was conducted to examine the effect of the difficulty index and discrimination index on iRT. Results iRT increases with increasing difficulty index, and iRT tends to decrease with increasing discrimination index. The students’ effort is increased when they solve difficult items but reduced when they are confronted with items with a high discrimination. The students’ test effort represented by iRT was properly maintained when the items have a ‘desirable’ difficulty and a ‘good’ discrimination. Conclusion The results of our study show that an adequate degree of item difficulty and discrimination is required to increase students’ motivation. It might be inferred that with the combination of CTT and iRT, we can gain insights about the quality of the examination and test behaviors of the students, which can provide us with more powerful tools to improve them

Draft genome sequence of a caprolactam degrader bacterium: Pseudomonas taiwanensis strain SJ9

AbstractPseudomonas taiwanensis strain SJ9 is a caprolactam degrader, isolated from industrial wastewater in South Korea and considered to have the potential for caprolactam bioremediation. The genome of this strain is approximately 6.2 Mb (G+C content, 61.75%) with 6,010 protein-coding sequences (CDS), of which 46% are assigned to recognized functional genes. This draft genome of strain SJ9 will provide insights into the genetic basis of its caprolactam-degradation ability

Selective Delivery of a Therapeutic Gene for Treatment of Head and Neck Squamous Cell Carcinoma Using Human Neural Stem Cells

ObjectivesBased on studies of the extensive tropism of neural stem cells (NSCs) toward malignant brain tumor, we hypothesized that NSCs could also target head and neck squamous cell carcinoma (HNSCC) and could be used as a cellular therapeutic delivery system.MethodsTo apply this strategy to the treatment of HNSCC, we used a human NSC line expressing cytosine deaminase (HB1.F3-CD), an enzyme that converts 5-fluorocytosine (5-FC) into 5-fluorouracil (5-FU), an anticancer agent. HB1. F3-CD in combination with 5-FC were cocultured with the HNSCC (SNU-1041) to examine the cytotoxicity on target tumor cells in vitro. For in vivo studies, an HNSCC mouse model was created by subcutaneous implantation of human HNSCC cells into athymic nude mice. HB1.F3-CD cells were injected into mice using tumoral, peritumoral, or intravenous injections, followed by systemic 5-FC administration.ResultsIn vitro, the HB1.F3-CD cells significantly inhibited the growth of an HNSCC cell line in the presence of the 5-FC. Independent of the method of injection, the HB1.F3-CD cells migrated to the HNSCC tumor, causing a significant reduction in tumor volume. In comparison to 5-FU administration, HB1.F3-CD cell injection followed by 5-FC administration reduced systemic toxicity, but achieved the same level of therapeutic efficacy.ConclusionTransplantation of human NSCs that express the suicide enzyme cytosine deaminase combined with systemic administration of the prodrug 5-FC may be an effective regimen for the treatment of HNSCC

Quorum Sensing System Affects the Plant Growth Promotion Traits of Serratia fonticola GS2.

Quorum sensing (QS) enables bacteria to organize gene expression programs, thereby coordinating collective behaviors. It involves the production, release, and population-wide detection of extracellular signaling molecules. The cellular processes regulated by QS in bacteria are diverse and may be used in mutualistic coordination or in response to changing environmental conditions. Here, we focused on the influence of the QS-dependent genes of our model bacterial strain Serratia fonticola GS2 on potential plant growth promoting (PGP) activities including indole-3-acetic acid (IAA) production, 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity, and biofilm formation. Based on genomic and phenotypic experimental data we identified and investigated the function of QS genes in the genome of the model strain. Our gene deletion study confirmed the biological functionality of the QS auto-inducer (gloI) and receptor (gloR) on potential PGP activities of GS2. A transcriptomic approach was also undertaken to understand the role of QS genes in regulation of genes primarily involved in PGP activities (IAA, ACC deaminase activity, and biofilm formation). Both transcriptomic and phenotypic data revealed that the QS-deletion mutants had considerably less PGP activities, as compared to the wild type. In addition, in vivo plant experiments showed that plants treated with GS2 had significantly higher growth rates than plants treated with the QS-deletion mutants. Overall, our results showed how QS-dependent genes regulate the potential PGP activities of GS2. This information may be helpful in understanding the relationship between QS-dependent genes and the PGP activity of bacteria, which aid in the production of practical bio-fertilizers for plant growth promotion

Whole Genome Analysis of Lactobacillus plantarum Strains Isolated From Kimchi and Determination of Probiotic Properties to Treat Mucosal Infections by Candida albicans and Gardnerella vaginalis

Three Lactobacillus plantarum strains ATG-K2, ATG-K6, and ATG-K8 were isolated from Kimchi, a Korean traditional fermented food, and their probiotic potentials were examined. All three strains were free of antibiotic resistance, hemolysis, and biogenic amine production and therefore assumed to be safe, as supported by whole genome analyses. These strains demonstrated several basic probiotic functions including a wide range of antibacterial activity, bile salt hydrolase activity, hydrogen peroxide production, and heat resistance at 70°C for 60 s. Further studies of antimicrobial activities against Candida albicans and Gardnerella vaginalis revealed growth inhibitory effects from culture supernatants, coaggregation effects, and killing effects of the three probiotic strains, with better efficacy toward C. albicans. In vitro treatment of bacterial lysates of the probiotic strains to the RAW264.7 murine macrophage cell line resulted in innate immunity enhancement via IL-6 and TNF-α production without lipopolysaccharide (LPS) treatment and anti-inflammatory effects via significantly increased production of IL-10 when co-treated with LPS. However, the degree of probiotic effect was different for each strain as the highest TNF-α and the lowest IL-10 production by the RAW264.7 cell were observed in the K8 lysate treated group compared to the K2 and K6 lysate treated groups, which may be related to genomic differences such as chromosome size (K2: 3,034,884 bp, K6: 3,205,672 bp, K8: 3,221,272 bp), plasmid numbers (K2: 3, K6 and K8: 1), or total gene numbers (K2: 3,114, K6: 3,178, K8: 3,186). Although more correlative inspections to connect genomic information and biological functions are needed, genomic analyses of the three strains revealed distinct genomic compositions of each strain. Also, this finding suggests genome level analysis may be required to accurately identify microorganisms. Nevertheless, L. plantarum ATG-K2, ATG-K6, and ATG-K8 demonstrated their potential as probiotics for mucosal health improvement in both microbial and immunological contexts

Abnormalities of Otoacoustic Emissions in Myasthenia Gravis: Association With Serological and Electrophysiological Features

Objective: To investigate whether otoacoustic emissions (OAEs) are impaired in patients with myasthenia gravis (MG) and whether such dysfunction is associated with serological and electrophysiological features of MG.Methods: We tested 15 patients with MG (30 ears) and 10 healthy age- and sex-matched subjects (20 ears) for transiently evoked OAE (TEOAE) and distortion product OAE (DPOAE).Results: Compared with controls, MG patients revealed a significant reduction in the amplitude of TEOAEs (p < 0.05) and DPOAEs at higher frequencies between 2,026 and 4,053 Hz (p < 0.05). In the subgroup analysis, TEOAE and DPOAE amplitudes were significantly lower in the acetylcholine receptor (AChR) antibody-positive group (p < 0.05) as well as in the repetitive nerve stimulation (RNS)-positive (p < 0.05) group. In particular, the OAE alteration significantly correlated with anti-AChR antibody titers. No significant difference of the OAEs was found between thymomatous and non-thymomatous MG or between purely ocular and generalized MG.Conclusions: Our study confirms that OAEs reveal subclinical dysfunction of the cholinergic neurotransmission of cochlear outer hair cells and correlate well with electrophysiological and serological characteristics of MG patients. Our findings imply that the measurement of OAEs might increase the diagnostic accuracy and help to monitor the severity of MG