Fluoroquinolone Resistance in <i>Salmonella</i>: Mechanisms, Fitness, and Virulence

Fluoroquinolones are highly effective broad-spectrum antibiotics usually used for the treatment of human and animal infections, including salmonellosis. Fluoroquinolones act against Salmonella by inhibiting their DNA replication. However, several zoonotic serotypes of Salmonella have developed resistance or are less susceptible to fluoroquinolones. Salmonella presents its resistance by substituting amino acids within the topoisomerase subunits, overexpression of multidrug efflux pumps, or decreasing the expression of outer membrane porins. The resistance level is further increased with the plasmid-mediated quinolone resistance genes which could horizontally transfer the resistance from strain to strain. The development of resistance in Salmonella shows that it is a multifactorial process and the acquisition of fluoroquinolone resistance might have significant influences on the bacterial fitness and virulence. Due to the high level resistance against fluoroquinolones that has been observed in Salmonella, care needs to be taken to avoid misuse and overuse of this important class of antibiotics to minimize the occurrence and dissemination of resistance

Fluoroquinolone Resistance in <i>Salmonella</i>: Mechanisms, Fitness, and Virulence

viii+52hlm;15,5x23,5c

A Bibliometric Approach to Characterizing Technology Readiness Levels Using Machine Learning

Presented at the AIAA SCITECH 2023 Forum in National Harbor, Maryland.As cislunar space becomes more accessible to national space agencies and commercial entities, there is a constant need to improve the way in which space missions are planned, and development progress is tracked. A technologies stage of development, which is related to mission budget and schedule, is typically quantified using technology readiness levels (TRL). The process of determining TRL is often long and laborious, and requires the use of subject matter experts. As a part of the Georgia Institute of Technology Cislunar Architecture Initiative, this work serves to develop the early stages of an environmental scanning approach to maturity assessment that allows for the automatic determination of a technologies TRL using machine learning ordinal regression techniques with bibliometric factors. The bibliometric factors considered were: scientific publications, National Science Foundation awards, patents, and NASA Spinoff articles. Annual data on these factors was collected for 31 technologies between 1995-2015 using public APIs, and S-curves fit to the data to estimate each technologies point in the development cycle. The final model performed with an R² of 0.817, 0.812, and 0.567 on the training, validation, and test data, respectively. Additionally, a better performing model to classify a technologies technology life cycle phase was created and drawbacks to this approach discussed

Regulation of neural progenitor cell state by ephrin-B

Maintaining a balance between self-renewal and differentiation in neural progenitor cells during development is important to ensure that correct numbers of neural cells are generated. We report that the ephrin-B–PDZ-RGS3 signaling pathway functions to regulate this balance in the developing mammalian cerebral cortex. During cortical neurogenesis, expression of ephrin-B1 and PDZ-RGS3 is specifically seen in progenitor cells and is turned off at the onset of neuronal differentiation. Persistent expression of ephrin-B1 and PDZ-RGS3 prevents differentiation of neural progenitor cells. Blocking RGS-mediated ephrin-B1 signaling in progenitor cells through RNA interference or expression of dominant-negative mutants results in differentiation. Genetic knockout of ephrin-B1 causes early cell cycle exit and leads to a concomitant loss of neural progenitor cells. Our results indicate that ephrin-B function is critical for the maintenance of the neural progenitor cell state and that this role of ephrin-B is mediated by PDZ-RGS3, likely via interacting with the noncanonical G protein signaling pathway, which is essential in neural progenitor asymmetrical cell division

Identification of novel and conserved microRNAs involved in fruit development and ripening in Fragaria vesca

MicroRNAs (miRNAs) are class of noncoding RNAs that regulate gene expression at the post-transcriptional level, either by endonucleolytic cleavage or by translational inhibition. Strawberry is a popular worldwide fresh fruit and is believed to benefit human health. However, the function of miRNAs during this fruit development and ripening remains unknown and miRNAs for specific for these processes are expected to be discovered. In the study, we identified 218 conserved miRNAs and 87 novel miRNAs in Fragaria vesca. Expression profiling of miRNAs during fruit development and ripening was performed, and the expression of targets of the miRNAs was validated by qRT-PCR (quantitative reverse transcription polymerase chain reaction). This study provided data for further research on molecular mechanisms involved in fruit development and ripening

Discovery and identification of potential biomarkers of papillary thyroid carcinoma

<p>Abstract</p> <p>Background</p> <p>Thyroid carcinoma is the most common endocrine malignancy and a common cancer among the malignancies of head and neck. Noninvasive and convenient biomarkers for diagnosis of papillary thyroid carcinoma (PTC) as early as possible remain an urgent need. The aim of this study was to discover and identify potential protein biomarkers for PTC specifically.</p> <p>Methods</p> <p>Two hundred and twenty four (224) serum samples with 108 PTC and 116 controls were randomly divided into a training set and a blind testing set. Serum proteomic profiles were analyzed using SELDI-TOF-MS. Candidate biomarkers were purified by HPLC, identified by LC-MS/MS and validated using ProteinChip immunoassays.</p> <p>Results</p> <p>A total of 3 peaks (<it>m/z </it>with 9190, 6631 and 8697 Da) were screened out by support vector machine (SVM) to construct the classification model with high discriminatory power in the training set. The sensitivity and specificity of the model were 95.15% and 93.97% respectively in the blind testing set. The candidate biomarker with <it>m/z </it>of 9190 Da was found to be up-regulated in PTC patients, and was identified as haptoglobin alpha-1 chain. Another two candidate biomarkers (6631, 8697 Da) were found down-regulated in PTC and identified as apolipoprotein C-I and apolipoprotein C-III, respectively. In addition, the level of haptoglobin alpha-1 chain (9190 Da) progressively increased with the clinical stage I, II, III and IV, and the expression of apolipoprotein C-I and apolipoprotein C-III (6631, 8697 Da) gradually decreased in higher stages.</p> <p>Conclusion</p> <p>We have identified a set of biomarkers that could discriminate PTC from non-cancer controls. An efficient strategy, including SELDI-TOF-MS analysis, HPLC purification, MALDI-TOF-MS trace and LC-MS/MS identification, has been proved successful.</p

E-beam nano-patterning for the ordered growth of GaN/InGaN nanorods

E-beam lithography was used to pattern a titanium mask on a GaN substrate with ordered arrays of nanoholes. This patterned mask served as a template for the subsequent ordered growth of GaN/InGaN nanorods by plasma-assisted molecular beam epitaxy. The mask patterning process was optimized for several holes configurations. The smallest holes were 30 nm in diameter with a pitch (center-to-center distance) of 100 nm only. High quality masks of several geometries were obtained that could be used to grow ordered GaN/InGaN nanorods with full selectivity (growth localized inside the nanoholes only) over areas of hundreds of microns. Although some parasitic InGaN growth occurred between the nanorods during the In incorporation, transmission electron microscopy and photoluminescence measurements demonstrated that these ordered nanorods exhibit high crystal quality and reproducible optical properties

The effect of metal-rich growth conditions on the microstructure of ScxGa1-xN films grown using molecular beam epitaxy

Epitaxial ScxGa1-xN films with 0 ≤ x ≤ 0.50 were grown using molecular beam epitaxy under metal-rich conditions. The ScxGa1-xN growth rate increased with increasing Sc flux despite the use of metal-rich growth conditions, which is attributed to the catalytic decomposition of N2 induced by the presence of Sc. Microstructural analysis showed that phase-pure wurtzite ScxGa1-xN was achieved up to x = 0.26, which is significantly higher than that previously reported for nitrogen-rich conditions, indicating that the use of metal-rich conditions can help to stabilise wurtzite phase ScxGa1-xN

The fibrinogen-to-albumin ratio is associated with intracranial atherosclerosis plaque enhancement on contrast-enhanced high-resolution magnetic resonance imaging

BackgroundContrast-enhanced high-resolution magnetic resonance imaging (CE-HR-MRI) is a useful imaging modality to assess vulnerable plaques in intracranial atherosclerotic stenosis (ICAS) patients. We studied the relationship between the fibrinogen-to-albumin ratio (FAR) and plaque enhancement in patients with ICAS.MethodsWe retrospectively enrolled consecutive ICAS patients who had undergone CE-HR-MRI. The degree of plaque enhancement on CE-HR-MRI was evaluated both qualitatively and quantitatively. Enrolled patients were classified into no enhancement, mild enhancement, and obvious enhancement groups. An independent association of the FAR with plaque enhancement was identified by multivariate logistic regression and receiver operating characteristic (ROC) curve analyses.ResultsOf the 69 enrolled patients, 40 (58%) were classified into the no/mild enhancement group, and 29 (42%) into the obvious enhancement group. The obvious enhancement group had a significantly higher FAR than the no/mild enhancement group (7.36 vs. 6.05, p = 0.001). After adjusting for potential confounders, the FAR was still significantly independently associated with obvious plaque enhancement in multiple regression analysis (odds ratio: 1.399, 95% confidence interval [CI]: 1.080–1.813; p = 0.011). ROC curve analysis revealed that FAR &gt;6.37 predicted obvious plaque enhancement with 75.86% sensitivity and 67.50% specificity (area under the ROC curve = 0.726, 95% CI: 0.606–0.827, p &lt; 0.001).ConclusionThe FAR can serve as an independent predictor of the degree of plaque enhancement on CE-HR-MRI in patients with ICAS. Also, as an inflammatory marker, the FAR has potential as a serological biomarker of intracranial atherosclerotic plaque vulnerability