Mathematical model of the firefly luciferase complementation assay reveals a non-linear relationship between the detected luminescence and the affinity of the protein pair being analyzed

© 2016 Dale et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. The firefly luciferase complementation assay is widely used as a bioluminescent reporter technology to detect protein-protein interactions in vitro, in cellulo, and in vivo. Upon the interaction of a protein pair, complemented firefly luciferase emits light through the adenylation and oxidation of its substrate, luciferin. Although it has been suggested that kinetics of light production in the firefly luciferase complementation assay is different from that in full length luciferase, the mechanism behind this is still not understood. To quantitatively understand the different kinetics and how changes in affinity of a protein pair affect the light emission in the assay, a mathematical model of the in vitro firefly luciferase complementation assay was constructed. Analysis of the model finds that the change in kinetics is caused by rapid dissociation of the protein pair, low adenylation rate of luciferin, and increased affinity of adenylated luciferin to the enzyme. The model suggests that the affinity of the protein pair has an exponential relationship with the light detected in the assay. This relationship causes the change of affinity in a protein pair to be underestimated. This study underlines the importance of understanding the molecular mechanism of the firefly luciferase complementation assay in order to analyze protein pair affinities quantitatively

Crystallographic orientation control of pure chromium via laser powder bed fusion and improved high temperature oxidation resistance

This is the first comprehensive study on the development of a cubic crystallographic texture in pure chromium (Cr) manufactured using laser powder bed fusion (LPBF) with different laser energy densities to alter its microstructure and high-temperature oxidation behavior. An increase in the laser energy density led to the formation of a strong crystallographic texture, which was preferentially oriented in the (100) plane, and there were microstructural improvements in the pure Cr. The grain size of the (100)-oriented Cr was larger than that of the randomly oriented Cr. In addition, the high-angle grain boundary and coincident site lattice (CSL) boundary characteristics were altered. The (100)-oriented Cr exhibited a decrease in the oxide thickness that was due to the decrease in the grain boundary density with a larger grain size and an increase in the CSL boundary ratio. In contrast, the Cr with a random texture showed higher oxidation kinetics and spallation of the oxide layer. The oxidation kinetics of the pure Cr manufactured using LPBF obeyed the parabolic rate law. However, the crystal orientation affected the oxidation of the Cr as the (100)-oriented pure Cr displayed a lower parabolic rate constant, indicating that the (100)-oriented Cr was oxidation-resistant. This is the first report to demonstrate the cubic crystallographic texture formation and the improvement of high-temperature oxidation resistance in Cr manufactured using LPBF.Gokcekaya O., Hayashi N., Ishimoto T., et al. Crystallographic orientation control of pure chromium via laser powder bed fusion and improved high temperature oxidation resistance. Additive Manufacturing, 36, 101624. https://doi.org/10.1016/j.addma.2020.101624

SIRT1 negatively regulates the expression of Prl2C3,a senescence-associated protein

SIRT1 is a mammalian homologue of yeast longevity protein Sir2. SIRT1 deacetylates transcription factors, cofactors, and histones in an NAD+-dependent manner, and promotes cell survival, anti-oxidative function, and DNA repair. Although some studies have indicated that SIRT1 is involved in longevity, the function of SIRT1 for preventing aging and senescence is still unclear. In mouse embryonic fibroblasts (MEFs), we found that SIRT1 expression decreased by aging and IRT1 reciprocally regulated the expression level of Prl2C3, one of the prolactin-like peptides. In young MEFs, purified Prl2C3 inhibited the growth and increased the number of senescence-associated β galactosidase-positive cells with enlarged and flattened shapes. Moreover, immunostaining of human skin sections showed the expression of Prl2C3 in the basal cells of the epidermis. These results indicate that SIRT1 negatively regulates a senescence-associated protein rl2C3

Convolutional neural network-based automatic liver delineation on contrast-enhanced and non-contrast-enhanced CT images for radiotherapy planning

AimThis study evaluated a convolutional neural network (CNN) for automatically delineating the liver on contrast-enhanced or non-contrast-enhanced CT, making comparisons with a commercial automated technique (MIM Maestro®).BackgroundIntensity-modulated radiation therapy requires careful labor-intensive planning involving delineation of the target and organs on CT or MR images to ensure delivery of the effective dose to the target while avoiding organs at risk.Materials and MethodsContrast-enhanced planning CT images from 101 pancreatic cancer cases and accompanying mask images showing manually-delineated liver contours were used to train the CNN to segment the liver. The trained CNN then performed liver segmentation on a further 20 contrast-enhanced and 15 non-contrastenhanced CT image sets, producing three-dimensional mask images of the liver.ResultsFor both contrast-enhanced and non-contrast-enhanced images, the mean Dice similarity coefficients between CNN segmentations and ground-truth manual segmentations were significantly higher than those between ground-truth and MIM Maestro software (p

Study on Fishery Household Management Improvement based on Interactive Information System

This paper presents a introduction of the developed system by that fisherman share various information. This system is characterized by the application of data mining methods and the introduction of IC tags. We compute the predict price formula by data mining of product value. The predict price of each port market can help a fishing boat to select a port for landing. And a part of this information is provided for market brokers. A fisherman and market brokers can perform their activity efficiently using this system. And we research the influence to which adding products information to marine products gives a consumer using IC tag. This IC tag has boilable, multi-access, and rewritable function. We wrote several information in IC tag, such as catching day, catching point, catching boat and so on, and researched an effect of adding information to consumers by the questionnaire. In this paper, we introduce the method of this investigation, and a part of result. In addition, we select the offshore trawl net fishery in Tajima, Hyogo Prefecture as a model area.Keywords: Distribution Efficiency, IC Tag, Demand and Supply, Taijima, Fisheries Economics, Interactive Informatio

Subsequent chemotherapy with paclitaxel plus cetuximab-based chemotherapy following immune checkpoint inhibitor in recurrent or metastatic squamous cell carcinoma of the head and neck

BackgroundImmune checkpoint inhibitors (ICIs) are essential in treating recurrent/metastatic squamous cell carcinoma of the head and neck (R/M SCCHN). However, the overall response rate (ORR) is limited to 10-20%, and subsequent chemotherapy is critical to maximizing the subjects’ prognosis.MethodsWe retrospectively reviewed 59 patients with R/M SCCHN treated with paclitaxel+cetuximab (PE)-based chemotherapy (PCE, paclitaxel+carboplatin+cetuximab; or PTX+Cmab, paclitaxel+cetuximab) following disease progression after either pembrolizumab or nivolumab monotherapy.ResultsOf 59 patients, 15 were treated with pembrolizumab, with an ORR of 13.3%, and the remaining 44 with nivolumab, with an ORR of 11.4%. All patients in the pembrolizumab cohort had platinum-sensitive disease. Following ICI treatment, 19 patients were treated with PCE and the remaining 40 with PTX+Cmab. PE-based chemotherapy induced favorable and prompt tumor shrinkage even in cases where ICI was not effective, with a median change in the summed dimensions of target lesions of -43.4%, resulting in an ORR of 62.7%. Median time to response was 1.8 months. The patients in the pembrolizumab cohort appeared to have a numerically higher response rate than those receiving nivolumab (80.0% vs. 56.8%). For the 59 patients, progression-free survival and overall survival, calculated from the initiation of PE-based chemotherapy, were 4.6 months and 17.1 months, respectively. Grade ≥3 adverse events occurred in 40.7%, and no treatment-related death was observed.ConclusionPE-based chemotherapy following ICI is encouraging for its robust antitumor efficacy in R/M SCCHN