Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Discovery of novel 4-hydroxyquinolines as indoleamine 2, 3-dioxygenase 1 inhibitors by virtual screening

Objective To discover novel indoleamine 2, 3-dioxygenase 1 (IDO1) inhibitors with new scaffold structures by screening ZINC and Chembridge databases using pharmacophore modeling and molecular docking. Methods We performed virtual screening of the ZINC database by molecular docking targeting the enzymatic active site of IDO1. The compounds with high scores were selected for enzyme activity test to find the new leads; A pharmacophore model was constructed based on 3 established IDO1 inhibitors that had been tested in clinical trials for virtual screening of the analogues of the lead compounds. The compounds matching the pharmacophore model were selected for inhibitory activity test, and the molecular dynamics was simulated to explore the binding mode of the compounds to IDO1. Results With molecular docking, we identified 11 lead compounds from more than 2 million virtual compounds and measured their enzyme activity. Among them, ZINC91657208 with a skeleton of 4-hydroxyquinoline was found to effectively inhibit the enzyme activity of IDO1 with an IC50 value of 77.15 μmol/L. Thirty-one analogues were obtained by substructure retrieval with 4-hydroxyquinoline skeleton. Ten compounds were selected by pharmacophore virtual screening and their inhibitory effect on the enzyme activity of IDO1 was tested. Three of the 10 compounds showed obvious inhibitory activities, and among them Chembridge29374490 had the lowest IC50 of 37.78 μmol/L, whose root mean square deviations (RMSD) of the skeleton were 1Å and 2.4Å after equilibrium by molecular dynamics simulation. Conclusion We identified new 4-hydroxyquinoline IDO1 inhibitors from ZINC and Chembridge databases

Progress in the Application of Biomimetic Mineralization for Tooth Repair

The tooth, including enamel and dentin, is a prominent biomineral that is produced by the biomineralization of living organisms. Although the mechanical performance of the tooth is outstanding, caries easily develop in a complex oral environment. The analysis of the chemical composition and the relationship between the mechanical properties and the structure is of great importance in solving caries. In this review, the multilevel structure and mechanical properties of enamel and dentin are briefly introduced, along with caries formation and the limitations of clinical dental restoration. Furthermore, the progress of the application of a wide range of biomimetic strategies for tooth remineralization is highlighted, including the use of calcium phosphate ionic clusters to construct the mineralization front, ensuring the oriented epitaxial growth of enamel crystals and replicating the complex structure of the enamel. Moreover, compared with the current clinical treatment, in which the resin composite and glass ionomer cement are the main repair materials and the high incidence of secondary caries leads to imperfect restorations, the remineralization tactics could achieve excellent repair effectiveness in reconstructing the complicated structure, restoring mechanical strength and gaining permanent repair. A basic understanding of enamel and dentin, their potential for restoration, and hopeful prospects for tooth repair that can be applied in the clinical setting, not just in the laboratory, is provided by this review

Binding interactions of epididymal protease inhibitor and semenogelin-1: a homology modeling, docking and molecular dynamics simulation study

Epididymal protease inhibitor (EPPIN) that is located on the sperm surface and specific to the male reproductive system is a non-hormonal contraceptive target, since the binding of EPPIN with the seminal plasma protein semenogelin-1 (SEMG1) causes a loss of sperm function. Here, we investigated the binding interactions between EPPIN and SEMG1 by homology modeling, docking and molecular dynamics simulation. Since no crystal structure was reported for EPPIN, its 3D structure was constructed by homology modeling and refined by dynamics simulation, illustrating the C-terminus domain of EPPIN could bind with its N-terminus domain through the residues 30–32 and 113–116. The binding interaction of SEMG110-8 peptide and EPPIN was investigated by Z-DOCK and dynamics simulation. After evaluating the models according to the calculated binding free energies, we demonstrated that C-terminus domain of EPPIN was important for the binding of SEMG1 via residues Tyr107, Gly112, Asn116, Gln118 and Asn122, while residue Arg32 in N-terminus domain also had contribution for their binding interaction. Additionally, the binding pocket of EPPIN was defined according to these key residues and verified by molecular docking with reported inhibitor EP055, suggesting that the pocket formed by Arg32, Asn114, Asn116, Phe117 and Asn122 could be important for the design of new ligands. This study might be helpful for the understanding of biological function of EPPIN and would encourage the discovery of non-hormonal contraceptive leads/drugs in the future

Research on Decorative and Integrated Thermal Insulation Board for External Wall

With the acceleration of globalization, industrialization and informatization, the consumption of energy resources is increasing, and the building energy consumption accounts for about 30%, so the building energy conservation has become an important part of energy conservation and emission reduction. At the same time of economic development, we should reduce building energy consumption and do a good job in building energy conservation [1], and put forward the following ways: the improvement of building’s own heat preservation and insulation performance; the improvement of energy utilization system efficiency such as electricity and heating; the development and utilization of new energy; and the proper management of energy utilization equipment system. Among them, the most effective way is to improve the thermal insulation performance of the building itself. The thermal insulation of enclosure and the air tightness of doors and windows are two important parts of thermal insulation. According to the relevant data [2], the heat loss of enclosure structure accounts for 40-50% of the building energy consumption, and the heat loss of wall structure accounts for about 70%. Therefore, the improvement of the thermal insulation requirements of the wall structure plays a huge role in building energy conservation In this paper, the experimental research on the exterior wall thermal insulation board of decoration and heat preservation integration is carried out. The influence of fly ash content, asbestos fiber content, composite active activator, waterproof agent and other additives on the physical properties of fiber-reinforced fly ash / cement board is discussed. The optimal content of various factors is determined and its mechanism is analyzed. The optimum proportion of fiber reinforced fly ash / cement board was determined by orthogonal test

Locomotion of miniature soft robots

Miniature soft robots are mobile devices, which are made of smart materials that can be actuated by external stimuli to realize their desired functionalities. Here, the key advancements and challenges of the locomotion producible by miniature soft robots in micro- to centimeter length scales are highlighted. It is highly desirable to endow these small machines with dexterous locomotive gaits as it enables them to easily access highly confined and enclosed spaces via a noninvasive manner. If miniature soft robots are able to capitalize this unique ability, they will have the potential to transform a vast range of applications, including but not limited to, minimally invasive medical treatments, lab-on-chip applications, and search-and-rescue missions. The gaits of miniature soft robots are categorized into terrestrial, aquatic, and aerial locomotion. Except for the centimeter-scale robots that can perform aerial locomotion, the discussions in this report are centered around soft robots that are in the micro- to millimeter length scales. Under each category of locomotion, prospective methods and strategies that can improve their gait performances are also discussed. This report provides critical analyses and discussions that can inspire future strategies to make miniature soft robots significantly more agile.National Research Foundation (NRF)Submitted/Accepted versionG.Z.L. was funded by the start-up grant awarded by Nanyang Technological University. P.S.L. was funded by the National Research Foundation Investigatorship Award, NRF-NRFI2016-05, awarded by the National Research Foundation, Prime Minister’s Office, Singapore

The Protective Effect of Theaflavins on the Kidney of Mice with Type II Diabetes Mellitus

Diabetic nephropathy, primarily caused by advanced glycation end products (AGEs), is a serious complication resulting from type 2 diabetes mellitus (T2DM). Reportedly, theaflavins (TFs) can improve diabetic nephropathy; however, the underlying molecular mechanism is not fully clear. In this study, T2DM mice were treated with different concentrations of TFs by gavage for 10 weeks to investigate the effect of TFs on diabetic nephropathy and their potential molecular mechanism of action. Biochemical and pathological analysis showed that the TFs effectively improved blood glucose, insulin resistance, kidney function, and other symptoms in diabetic mice. The mechanism studies indicated that TFs inhibited the formation of AGEs, thereby inhibiting the activation of the MAPK/NF-κB signaling pathway. Therefore, our study suggested that TFs improved diabetic nephropathy by inhibiting the formation of AGEs

Treatment of insulinomas by laparoscopic radiofrequency ablation: case reports and literature review

Despite its rarity, insulinoma is the most common type of pancreatic endocrine neoplasm, with an occurrence of 1 to 5 per million per year in the population. Surgical resection or enucleation is the first line of curative treatment choice for insulinoma. Eight patients with symptomatic insulinomas treated by radiofrequency ablation have been described since 2009. In the past two years, we treated two patients with symptomatic insulinomas (one in the pancreatic tail and the other in the pancreatic neck) successfully using laparoscopic radiofrequency ablation. Both patients achieved complete elimination without any significant complications. Our study suggests laparoscopic radiofrequency ablation could be developed as a safe and effective alternative treatment to surgery for the patients with insulinomas who refuse or are not eligible for surgery

The mTOR/p70S6K/ RPS6/4E-BP1 signaling pathway was involved in T2A-induced inhibition of HIF-1α.

<p>(A) The MDA-MB-231 cells were treated without or with various concentrations of T2A for 24 hours under normoxic and hypoxic conditions. Whole cell extracts were prepared from cells and subjected to Western blot assay using antibodies against phospho-mTOR (p-mTOR), mTOR, p70S6 Kinase(p70S6K), p-p70S6K (Thr421/Ser424), p-p70S6K(Thr389), S6 Ribosomal Protein (RPS6), p-RPS6(Ser235/236), p-RPS6(Ser240/244), 4E-BP1, and p-4E-BP1(Thr37/46). (B) Cells were pretreated with rapamycin (20 nM) for 2 hours, followed by T2A treatment (20 μM) under normoxic or hypoxic conditions as described above. Whole cell extracts were analyzed by Western blot using antibodies as indicated. (C) VEGF in the supernatant was evaluated using ELISA. Error bars represent means ± SD (n = 3). Values of cells treated with T2A and rapamycin were significantly reduced compared to values obtained from cells treated with T2A alone based on Student’s t-test; **<i>P</i> <0.01.</p