42 research outputs found

    A study on stability analysis of atrial repolarization variability using ARX model in sinus rhythm and atrial tachycardia ECGs

    Get PDF
    © 2016 Elsevier Ireland Ltd Background The interaction between the PTa and PP interval dynamics from the surface ECG is seldom explained. Mathematical modeling of these intervals is of interest in finding the relationship between the heart rate and repolarization variability. Objective The goal of this paper is to assess the bounded input bounded output (BIBO) stability in PTa interval (PTaI) dynamics using autoregressive exogenous (ARX) model and to investigate the reason for causing instability in the atrial repolarization process. Methods Twenty-five male subjects in normal sinus rhythm (NSR) and ten male subjects experiencing atrial tachycardia (AT) were included in this study. Five minute long, modified limb lead (MLL) ECGs were recorded with an EDAN SE-1010 PC ECG system. The number of minute ECGs with unstable segments (N us ) and the frequency of premature activation (PA) (i.e. atrial activation) were counted for each ECG recording and compared between AT and NSR subjects. Results The instability in PTaI dynamics was quantified by measuring the numbers of unstable segments in ECG data for each subject. The unstable segments in the PTaI dynamics were associated with the frequency of PA. The presence of PA is not the only factor causing the instability in PTaI dynamics in NSR subjects, and it is found that the cause of instability is mainly due to the heart rate variability (HRV). C onclusion The ARX model showed better prediction of PTa interval dynamics in both groups. The frequency of PA is significantly higher in AT patients than NSR subjects. A more complex model is needed to better identify and characterize healthy heart dynamics

    X-Ray Crystal Structure Analysis of Selected Benzimidazole Derivatives

    Get PDF
    This chapter describes the X-ray crystal structure analysis of selected benzimidazole derivatives, viz. BIP: 2-(1H-benzimidazol-2-yl)phenol, MBMPBI: 1-(4-methylbenzyl)-2-(4-methylphenyl)-1H-benzimidazole, DPBI: 1,2-diphenyl-1H-benzimidazole, PBIP: 2-(1-phenyl-1H-benzimidazol-2-yl)phenol, FPPBI: 2-(4-fluorophenyl)-1-phenyl-1H-benzimidazole and NPBIBHS: 2-(naphthalen-1-yl)-1-phenyl-1H-benzimidazole benzene hemisolvate. The BIP molecule is planar, and in the crystal, it is arranged in parallel planes, stabilised by π-π interactions and the hydrogen bonds. In MBMPBI, benzimidazole cores of the two independent (A and B) molecules are planar. Two C▬H…N hydrogen bonds link B molecules only, forming centrosymmetric dimers with R22(8) ring motifs. In the DPBI molecule, the benzimidazole core is planar: one hydrogen-bond interaction (C▬H…N) and C▬H…π (three) interaction leading to the three-dimensional arrangement. In the PBIP molecule, the benzimidazole is nearly planar. The hydrogen bonds and a π-π stacking interaction are present in the crystal. In the FPPBI molecule, the benzimidazole unit is almost planar. The C▬H…F hydrogen bonds and weak C▬H…π interactions lead to a three-dimensional architecture in the crystal. In NPBIBHS, the naphthalene fragment lies out of the plane about the benzimidazole core unit. The C▬H…N hydrogen bonds and C▬H…π interactions lead to a three-dimensional architecture in the crystal

    Engineering principles and process designs for phosphorus recovery as struvite: A comprehensive review

    Get PDF
    The rising population relies heavily on expensive phosphate (P) fertilizers for its agricultural productivity that qualms the national food security. Globally, there is a growing concern for the profound reliance on finite phosphorite reservoirs for commercial phosphate fertilizers’ qualitative and quantitative production. On the contrary, uncontrolled discharging of nutrient-rich wastewaters into natural streams, affecting the aquatic ecosystem. These critical situations have caused a scientific threat that has forced the researchers to explore other opportunities for the conservation of nutrient resources, recovery, and recycling. This review examines the nutrient recovery paradigms for struvite production by curtailing the nutrient gap between wastewater treatment and agricultural productivity. It comprehends the fundamental chemistry, thermodynamics, and factors influencing the struvite production process with its detailed mechanisms. Further, it deliberates the possible struvite engineering strategies, including process designs to enhance P recovery at the lab, pilot, and commercial scale. Also, it emphasizes the applications of nutrient-loaded struvite as a slow-release fertilizer and the challenges associated with economic feasibility and scaling up of the process in recent decades

    Structure and mapping of spontaneous mutational sites of PyrR from Mycobacterium tuberculosis

    No full text
    The emergence of resistant Mycobacterium tuberculosis (Mtb) infection and the dearth of drugs against tuberculosis have made it imperative to identify and validate novel targets and classes of drugs for treatment. The pyrimidine operon regulatory protein (PyrR), a regulator of de novo pyrimidine synthesis, is an essential enzyme and a probable 5-fluorouracil (5-FU) target in Mtb, with mutations in PyrR attributable to 5-FU resistance. Here we report, for the first time, the co-crystal structure of the PyrR-5-FU complex along with mapping of spontaneous mutational sites of PyrR. A cluster of mutations in the presence of the drug usually indicates a plausible region of drug-target interaction. Notably, we observed that three of the mutated PyrR residues lie in close proximity to the 5-FU binding site, including the amino acid Val178, which is involved in water mediated hydrogen bonding contact with 5-FU. Computational modeling of the PyrR-5'-phosphoribosyl-α-1'-pyrophosphate (PRPP) complex revealed the location of several other mutations at the PRPP binding site of PyrR, indicating their probable role in resistance. Indeed, 5-FU-resistant strains harboring these mutations exhibited decreased susceptibility to 5-FU. Considering that pyrimidine analogs are predominantly regarded to inhibit PyrR, the present studies will be beneficial for the screening of appropriate inhibitors of PyrR and help provide insight into future TB drug design and development

    Crystallization of uracil phosphoribosyltransferase (MtUPRT) from Mycobacterium tuberculosis

    No full text
    Exploring new drug targets in parallel to designing strategies for rational use of existing drugs would greatly aid the Tuberculosis (TB) drug development program. The key enzymes involved in the essential metabolic and regulatory pathways are usually sought for in the pursuit of potential drug targets. Likewise, uracil phosphoribosyltransferase (UPRT) is a key enzyme in the synthesis uridine 5’-monophosphate (UMP), the precursor of the pyrimidine nucleotides. It has been recently shown to be the probable target of 5-fluorouracil in Mycobacterium tuberculosis (Mtb). Here we report the purification, characterization and crystallization of the full length UPRT from Mtb (MtUPRT) encoded by the gene upp (Rv3309c). The MtUPRT was overexpressed in BL21 (DE3) E.coli expression system followed by three step chromatographic purification procedures. The purified MtUPRT was concentrated to 8mg/ml; single crystals were obtained using the sitting drop vapour diffusion method. The crystals were diffracted to 3.0 Å resolution and belonged to the space group P32 with unit cell parameters a = b = 118.09, c = 77.88 Å and four monomers in the asymmetric unit. Understanding the three dimensional structure of this essential enzyme will greatly help in screening of appropriate inhibitors of MtUPRT and thus assist in TB drug development
    corecore