1,348 research outputs found

    Chromosomally encoded gyrase inhibitor GyrI protects Escherichia coli against DNA-damaging agents

    Get PDF
    DNA gyrase, a type II topoisomerase, is the sole supercoiling activity in the cell and is essential for cell survival. There are two proteinaceous inhibitors of DNA gyrase that are plasmid-borne and ensure maintenance of the plasmids in bacterial populations. However, the physiological role of GyrI, an inhibitor of DNA gyrase encoded by the Escherichia coli genome, has been elusive. Previously, we have shown that GyrI imparts resistance against microcin B17 and CcdB. Here, we find that GyrI provided partial/limited protection against the quinolone class of gyrase inhibitors but had no effect on inhibitors that interfere with the ATPase activity of the enzyme. Moreover, GyrI negated the effect of alkylating agents, such as mitomycin C and N-methyl-N-nitro-N-nitrosoguanidine, that act independently of DNA gyrase. Hence, in vivo, GyrI appears to be involved in reducing DNA damage from many sources. In contrast, GyrI is not effective against lesions induced by ultraviolet radiation. Furthermore, the expression of GyrI does not significantly alter the topology of DNA. Thus, although isolated as an inhibitor of DNA gyrase, GyrI seems to have a broader role in vivo than previously envisaged

    Animation - a study and comparison of concepts and software issues

    Get PDF
    This paper examines animation from several different views – historical through the modern computer generated. It covers a short history of animation with a detailed look at some of the early examples with an emphasis on the techniques and tricks used in their creation. It also looks at how computers have changed the animation industry and expanded it into other occupations such as architectural modeling. A comparison between traditional and computer animation processes is noted as well as a look at software, its components, usability, and more. Types of and processes for rendering are also described and compared

    Kinetics in Individuals with Unilateral Transtibial Amputations Using Running-Specific Prostheses

    Get PDF
    Improvements in rehabilitation and prosthetic design are needed to help promote activities such as running that increase physical activity levels of individuals with lower extremity amputation (ILEA). However, effectively developing these improvements requires a detailed understanding of prosthetic and ILEA running biomechanics. Running-specific prostheses (RSPs) have been developed to improve running performance for ILEA runners, but altered running kinetics may still be necessary to accommodate for the loss of musculoskeletal function caused by lower extremity amputation. The few studies investigating ILEA running with RSPs focus on maximal performance, but our understanding of how ILEA using RSPs modulate kinetics to run at submaximal velocities remains limited. The purpose of this study was to characterize changes in kinetics and mechanical energy across a range of running velocities in ILEA wearing RSPs. This dissertation investigated six specific aims through six corresponding experiments that improve our knowledge of mechanical and anthropometric properties of RSPs and the kinetic profiles of ILEA running at submaximal velocities. Four common RSP designs were tested for mechanical and anthropometric properties. ILEA with unilateral transtibial amputations who wear RSPs and an able-bodied control group participated in the running experiments. Mechanical and anthropometric results indicated that RSP marker placement had little effect on joint kinetic estimations proximal to the prostheses, and trifilar pendulums can measure moments of inertia with <1% error. The running experiments provided the first 3D kinetic descriptions of ILEA running. The prosthetic limb typically generated lower peak kinetic parameters and 50% lower total mechanical work than the intact and control limbs, indicating a greater reliance on the intact limb. To counter the prosthetic limb deficiencies, ILEA increased stride frequencies compared to control subjects. Additionally, the prosthetic limb demonstrated prolonged periods of anterior ground reaction force to increase propulsive impulse and prolonged hip stance phase extension moments that generated increased hip concentric work. The data indicated that ILEA wearing RSPs run differently than able-bodied runners and use several adaptive mechanisms to run at the same velocity and to increase running velocity. These mechanisms are discussed and future directions of research are suggested

    GLIMEPIRIDE FAST DISINTEGRATING TABLETS: FORMULATION, EVALUATION AND IN-VIVO DISINTEGRATION AND DYNAMIC STUDIES

    Get PDF
    Objective: The main objective of the research was to formulate directly compressible fast disintegrating tablets of glimepiride by using different super disintegrants such as crospovidone, croscarmellose sodium, sodium starch glycolate and L-HPC in various concentrations.Methods: The prepared tablets were evaluated for various tablet properties like weight variation, thickness, hardness, friability, taste, drug content, in vitro and in vivo disintegration time, and in vitro drug release, in vivo dynamic studies. Other parameters such as wetting time, water absorption ratio, and drug-excipient compatibility were also evaluated.Results: The disintegration time of the optimized fast disintegrating tablet formulation was observed to be 12 s in vitro and 19.80 s in vivo. The correlation was observed between disintegration time and ‘R' for each of the four super disintegrants at the concentrations studied. Considering the ‘R' values and disintegration time, croscarmellose sodium was significantly superior compared to the other super disintegrants tested. Drug release was faster from formulations containing 25% croscarmellose sodium compared to the pure drug and without super disintegrant glimepiride tablet. FTIR studies did not indicate any excipient incompatibility, either during mixing or after compression. Optimized formulation exhibited good results in the decrease in blood glucose in rats when compared to the pure drug and marketed product.Conclusion: Form the results if this study it can be concluded that prepared optimized fast disintegrating tablets of glimepiride are the better option to treat diabetes.Keywords: Superdisintegrants, Fast disintegrating tablets, Disintegration time, Water absorption ratio, Wetting time, Dissolution, Dynamic studie

    Mid-Infrared laser spectroscopy detection and quantification of explosives in soils using multivariate analysis and artificial intelligence

    Get PDF
    A tunable quantum cascade laser (QCL) spectrometer was used to develop methods for detecting and quantifying high explosives (HE) in soil based on multivariate analysis (MVA) and artificial intelligence (AI). For quantification, mixes of 2,4-dinitrotoluene (DNT) of concentrations from 0% to 20% w/w with soil samples were investigated. Three types of soils, bentonite, synthetic soil, and natural soil, were used. A partial least squares (PLS) regression model was generated for predicting DNT concentrations. To increase the selectivity, the model was trained and evaluated using additional analytes as interferences, including other HEs such as pentaerythritol tetranitrate (PETN), trinitrotoluene (TNT), cyclotrimethylenetrinitramine (RDX), and non-explosives such as benzoic acid and ibuprofen. For the detection experiments, mixes of different explosives with soils were used to implement two AI strategies. In the first strategy, the spectra of the samples were compared with spectra of soils stored in a database to identify the most similar soils based on QCL spectroscopy. Next, a preprocessing based on classical least squares (Pre-CLS) was applied to the spectra of soils selected from the database. The parameter obtained based on the sum of the weights of Pre-CLS was used to generate a simple binary discrimination model for distinguishing between contaminated and uncontaminated soils, achieving an accuracy of 0.877. In the second AI strategy, the same parameter was added to a principal component matrix obtained from spectral data of samples and used to generate multi-classification models based on different machine learning algorithms. A random forest model worked best with 0.996 accuracy and allowing to distinguish between soils contaminated with DNT, TNT, or RDX and uncontaminated soils
    • …
    corecore