Displaying publications 241 - 260 of 616 in total

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  1. Wi NT, Loo CK, Chockalingam L
    Int J Neural Syst, 2012 Dec;22(6):1250029.
    PMID: 23186278 DOI: 10.1142/S0129065712500293
    A small change in image will cause a dramatic change in signals. Visual system is required to be able to ignore these changes, yet specific enough to perform recognition. This work intends to provide biological-backed insights into 2D translation and scaling invariance and 3D pose-invariance without imposing strain on memory and with biological justification. The model can be divided into lower and higher visual stages. Lower visual stage models the visual pathway from retina to the striate cortex (V1), whereas the modeling of higher visual stage is mainly based on current psychophysical evidences.
    Matched MeSH terms: Computer Simulation/statistics & numerical data*
  2. Govindaraju K, Viswanathan GN, Badruddin IA, Kamangar S, Salman Ahmed NJ, Al-Rashed AA
    Comput Methods Biomech Biomed Engin, 2016 Nov;19(14):1541-9.
    PMID: 27052093 DOI: 10.1080/10255842.2016.1170119
    This study aims to investigate the influence of artery wall curvature on the anatomical assessment of stenosis severity and to identify a region of misinterpretation in the assessment of per cent area stenosis (AS) for functionally significant stenosis using fractional flow reserve (FFR) as standard. Five artery models of different per cent AS severity (70, 75, 80, 85 and 90%) were considered. For each per cent AS severity, the angle of curvature of the arterial wall varied from straight to an increasingly curved model (0°, 30°, 60°, 90° and 120°). Computational fluid dynamics was performed under transient physiologic hyperemic flow conditions to investigate the influence of artery wall curvature on the pressure drop and the FFR. The findings in this study may be useful in in vitro anatomical assessment of functionally significant stenosis. The FFR decreased with increasing stenosis severity for a given curvature of the artery wall. Moreover, a significant decrease in FFR was found between straight and curved models discussed for a given severity condition. These findings indicate that the curvature effect was included in the FFR assessment in contrast to minimum lumen area (MLA) or per cent AS assessment. The MLA or per cent AS assessment may lead to underestimation of stenosis severity. From this numerical study, an uncertainty region could be evaluated using the clinical FFR cutoff value of 0.8. This value was observed at 81.98 and 79.10% AS for arteries with curvature angles of 0° and 120° respectively. In conclusion, the curvature of the artery should not be neglected in in vitro anatomical assessment.
    Matched MeSH terms: Computer Simulation*
  3. Gavai AK, Supandi F, Hettling H, Murrell P, Leunissen JA, van Beek JH
    PLoS One, 2015;10(3):e0119016.
    PMID: 25806817 DOI: 10.1371/journal.pone.0119016
    Predicting the distribution of metabolic fluxes in biochemical networks is of major interest in systems biology. Several databases provide metabolic reconstructions for different organisms. Software to analyze flux distributions exists, among others for the proprietary MATLAB environment. Given the large user community for the R computing environment, a simple implementation of flux analysis in R appears desirable and will facilitate easy interaction with computational tools to handle gene expression data. We extended the R software package BiGGR, an implementation of metabolic flux analysis in R. BiGGR makes use of public metabolic reconstruction databases, and contains the BiGG database and the reconstruction of human metabolism Recon2 as Systems Biology Markup Language (SBML) objects. Models can be assembled by querying the databases for pathways, genes or reactions of interest. Fluxes can then be estimated by maximization or minimization of an objective function using linear inverse modeling algorithms. Furthermore, BiGGR provides functionality to quantify the uncertainty in flux estimates by sampling the constrained multidimensional flux space. As a result, ensembles of possible flux configurations are constructed that agree with measured data within precision limits. BiGGR also features automatic visualization of selected parts of metabolic networks using hypergraphs, with hyperedge widths proportional to estimated flux values. BiGGR supports import and export of models encoded in SBML and is therefore interoperable with different modeling and analysis tools. As an application example, we calculated the flux distribution in healthy human brain using a model of central carbon metabolism. We introduce a new algorithm termed Least-squares with equalities and inequalities Flux Balance Analysis (Lsei-FBA) to predict flux changes from gene expression changes, for instance during disease. Our estimates of brain metabolic flux pattern with Lsei-FBA for Alzheimer's disease agree with independent measurements of cerebral metabolism in patients. This second version of BiGGR is available from Bioconductor.
    Matched MeSH terms: Computer Simulation*
  4. Sim SF, Ling TY, Lau S, Jaafar MZ
    Environ Monit Assess, 2015 Apr;187(4):181.
    PMID: 25773897 DOI: 10.1007/s10661-015-4416-7
    A computer-aided multivariate water quality index is developed based on partial least squares (PLS) regression. The index is termed as the partial least squares water quality index (PLS-WQI). Briefly, a training set was computationally generated based on the guideline of National Water Quality Standards for Malaysia (NWQS) to predict the water quality. The index is benchmarked with the well-established index developed by the Department of Environment, Malaysia (DOE-WQI). The PLS-WQI is a continuous variable with the value closer to I indicating good water quality and closer to V indicating poor water quality. Unlike other conventional indexing methods, the algorithm calculates the index in a multivariate manner. The algorithm allows rapid processing of a large dataset without tedious calculation; it can be an efficient tool for spatial and temporal routine monitoring of water quality. Although the algorithm is designed based on the guideline of NWQS, it can be easily adapted to accommodate other guidelines. The algorithm was evaluated and demonstrated on the simulated and real datasets. Results indicate that the algorithm is robust and reliable. Based on six parameters, the overall ratings derived are inversely correlated to DOE-WQI. When the number of parameter is increased, the overall ratings appear to provide better insights into the water quality.
    Matched MeSH terms: Computer Simulation*
  5. Conroy-Beam D, Buss DM, Asao K, Sorokowska A, Sorokowski P, Aavik T, et al.
    Sci Rep, 2019 11 15;9(1):16885.
    PMID: 31729413 DOI: 10.1038/s41598-019-52748-8
    Humans express a wide array of ideal mate preferences. Around the world, people desire romantic partners who are intelligent, healthy, kind, physically attractive, wealthy, and more. In order for these ideal preferences to guide the choice of actual romantic partners, human mating psychology must possess a means to integrate information across these many preference dimensions into summaries of the overall mate value of their potential mates. Here we explore the computational design of this mate preference integration process using a large sample of n = 14,487 people from 45 countries around the world. We combine this large cross-cultural sample with agent-based models to compare eight hypothesized models of human mating markets. Across cultures, people higher in mate value appear to experience greater power of choice on the mating market in that they set higher ideal standards, better fulfill their preferences in choice, and pair with higher mate value partners. Furthermore, we find that this cross-culturally universal pattern of mate choice is most consistent with a Euclidean model of mate preference integration.
    Matched MeSH terms: Computer Simulation*
  6. Arfan M, Siddiqui SZ, Abbasi MA, Rehman A, Shah SAA, Ashraf M, et al.
    Pak J Pharm Sci, 2018 Nov;31(6 (Supplementary):2697-2708.
    PMID: 30587482
    The research was aimed to unravel the enzymatic potential of sequentially transformed new triazoles by chemically converting 4-methoxybenzoic acid via Fischer's esterification to 4-methoxybenzoate which underwent hydrazinolysis and the corresponding hydrazide (1) was cyclized with phenyl isothiocyanate (2) via 2-(4-methoxybenzoyl)-N-phenylhydrazinecarbothioamide (3); an intermediate to 5-(4-methoxyphenyl)-4-phenyl-4H-1,2,4-triazol-3-thiol (4). The electrophiles; alkyl halides 5(a-g) were further reacted with nucleophilic S-atom to attain a series of S-alkylated 5-(4-methoxyphenyl)-4-phenyl-4H-1,2,4-triazole-3-thiols 6(a-g). Characterization of synthesized compounds was accomplished by contemporary spectral techniques such as FT-IR, 1H-NMR, 13C-NMR and EI-MS. Excellent cholinesterase inhibitory potential was portrayed by 3-(n-heptylthio)-5-(4-methoxyphenyl)-4-phenyl-4H-1,2,4-triazole; 6g against AChE (IC50; 38.35±0.62μM) and BChE (IC50; 147.75±0.67μM) enzymes. Eserine (IC50; 0.04±0.01μM) was used as reference standard. Anti-proliferative activity results ascertained that derivative encompassing long straight chain substituted at S-atom of the moiety was the most potent with 4.96 % cell viability (6g) at 25μM and with 2.41% cell viability at 50μMamong library of synthesized derivatives. In silico analysis also substantiated the bioactivity statistics.
    Matched MeSH terms: Computer Simulation*
  7. Virk NA, Rehman A, Abbasi MA, Siddiqui SZ, Ashraf A, Lateef M, et al.
    Pak J Pharm Sci, 2018 Nov;31(6 (Supplementary):2645-2654.
    PMID: 30587474
    Microwave and conventional techniques were employed to synthesize a novel array of compounds 7a-g with 1,2,4-triazole and piperidine rings having great biological importance. The microwave assisted method has a better operational scope with respect to time and yield comparative to the conventional method. 1H-NMR, 13C-NMR and IR techniques were employed to justify the structure of synthesized compounds. The antioxidant, butyrylcholinesterase inhibition and urease inhibition potential of every synthesized compound was evaluated. Every member of the synthesized series was found potent against mentioned activities. Compound 7g was the most active anti-urease agent having IC50 (μM) value 16.5±0.09 even better than the thiourea with an IC50(μM) value of 24.3±0.24. The better urease inhibition potential of 7g was also elaborated and explained by docking and bovine serum albumin (BSA) binding studies.
    Matched MeSH terms: Computer Simulation*
  8. Sim EU, Talwar SP
    BMC Mol Cell Biol, 2019 08 15;20(1):34.
    PMID: 31416416 DOI: 10.1186/s12860-019-0219-y
    BACKGROUND: Association of Epstein-Barr virus (EBV) encoded latent gene products with host ribosomal proteins (RPs) has not been fully explored, despite their involvement in the aetiology of several human cancers. To gain an insight into their plausible interactions, we employed a computational approach that encompasses structural alignment, gene ontology analysis, pathway analysis, and molecular docking.

    RESULTS: In this study, the alignment analysis based on structural similarity allows the prediction of 48 potential interactions between 27 human RPs and the EBV proteins EBNA1, LMP1, LMP2A, and LMP2B. Gene ontology analysis of the putative protein-protein interactions (PPIs) reveals their probable involvement in RNA binding, ribosome biogenesis, metabolic and biosynthetic processes, and gene regulation. Pathway analysis shows their possible participation in viral infection strategies (viral translation), as well as oncogenesis (Wnt and EGFR signalling pathways). Finally, our molecular docking assay predicts the functional interactions of EBNA1 with four RPs individually: EBNA1-eS10, EBNA1-eS25, EBNA1-uL10 and EBNA1-uL11.

    CONCLUSION: These interactions have never been revealed previously via either experimental or in silico approach. We envisage that the calculated interactions between the ribosomal and EBV proteins herein would provide a hypothetical model for future experimental studies on the functional relationship between ribosomal proteins and EBV infection.

    Matched MeSH terms: Computer Simulation*
  9. Soong JX, Chan SK, Lim TS, Choong YS
    J Comput Aided Mol Des, 2019 03;33(3):375-385.
    PMID: 30689080 DOI: 10.1007/s10822-019-00186-z
    Mycobacterium tuberculosis (Mtb) 16.3 kDa heat shock protein 16.3 (HSP16.3) is a latency-associated antigen that can be targeted for latent tuberculosis (TB) diagnostic and therapeutic development. We have previously developed human VH domain antibodies (dAbs; clone E3 and F1) specific against HSP16.3. In this work, we applied computational methods to optimise and design the antibodies in order to improve the binding affinity with HSP16.3. The VH domain antibodies were first docked to the dimer form of HSP16.3 and further sampled using molecular dynamics simulation. The calculated binding free energy of the HSP16.3-dAb complexes showed non-polar interactions were responsible for the antigen-antibody association. Per-residue free energy decomposition and computational alanine scanning have identified one hotspot residue for E3 (Y391) and 4 hotspot residues for F1 (M394, Y396, R397 and M398). These hotspot residues were then mutated and evaluated by binding free energy calculations. Phage ELISA assay was carried out on the potential mutants (E3Y391W, F1M394E, F1R397N and F1M398Y). The experimental assay showed improved binding affinities of E3Y391W and F1M394E against HSP16.3 compared with the wild type E3 and F1. This case study has thus showed in silico methods are able to assist in optimisation or improvement of antibody-antigen binding.
    Matched MeSH terms: Computer Simulation*
  10. Calero R, Mirabal M, Bouza J, Guzmán MV, Carrillo H, López Y, et al.
    BMC Immunol, 2013;14 Suppl 1:S9.
    PMID: 23458073 DOI: 10.1186/1471-2172-14-S1-S9
    TB, caused by Mycobacterium tuberculosis (MTB), is one of the major global infectious diseases. For the pandemic control, early diagnosis with sensitive and specific methods is fundamental. With the advent of bioinformatics' tools, the identification of several proteins involved in the pathogenesis of TB (TB) has been possible. In the present work, the MTB genome was explored to look for molecules with possible antigenic properties for their evaluation as part of new generation diagnostic kits based on the release of cytokines. Seven proteins from the MTB proteome and some of their combinations suited the computational test and the results suggested their potential use for the diagnosis of infection in the following population groups: Cuba, Mexico, Malaysia and sub-Saharan Africa. Our predictions were performed using public bioinformatics tools plus three computer programs, developed by our group, to facilitate information retrieval and processing.
    Matched MeSH terms: Computer Simulation*
  11. Al-Thiabat MG, Saqallah FG, Gazzali AM, Mohtar N, Yap BK, Choong YS, et al.
    Molecules, 2021 Feb 18;26(4).
    PMID: 33670773 DOI: 10.3390/molecules26041079
    Folate receptor alpha (FRα) is known as a biological marker for many cancers due to its overexpression in cancerous epithelial tissue. The folic acid (FA) binding affinity to the FRα active site provides a basis for designing more specific targets for FRα. Heterocyclic rings have been shown to interact with many receptors and are important to the metabolism and biological processes within the body. Nineteen FA analogs with substitution with various heterocyclic rings were designed to have higher affinity toward FRα. Molecular docking was used to study the binding affinity of designed analogs compared to FA, methotrexate (MTX), and pemetrexed (PTX). Out of 19 FA analogs, analogs with a tetrazole ring (FOL03) and benzothiophene ring (FOL08) showed the most negative binding energy and were able to interact with ASP81 and SER174 through hydrogen bonds and hydrophobic interactions with amino acids of the active site. Hence, 100 ns molecular dynamics (MD) simulations were carried out for FOL03, FOL08 compared to FA, MTX, and PTX. The root mean square deviation (RMSD) and root mean square fluctuation (RMSF) of FOL03 and FOL08 showed an apparent convergence similar to that of FA, and both of them entered the binding pocket (active site) from the pteridine part, while the glutamic part was stuck at the FRα pocket entrance during the MD simulations. Molecular mechanics Poisson-Boltzmann surface accessible (MM-PBSA) and H-bond analysis revealed that FOL03 and FOL08 created more negative free binding and electrostatic energy compared to FA and PTX, and both formed stronger H-bond interactions with ASP81 than FA with excellent H-bond profiles that led them to become bound tightly in the pocket. In addition, pocket volume calculations showed that the volumes of active site for FOL03 and FOL08 inside the FRα pocket were smaller than the FA-FRα system, indicating strong interactions between the protein active site residues with these new FA analogs compared to FA during the MD simulations.
    Matched MeSH terms: Computer Simulation*
  12. Wan Hassan WN, Othman SA, Chan CS, Ahmad R, Ali SN, Abd Rohim A
    Am J Orthod Dentofacial Orthop, 2016 Nov;150(5):886-895.
    PMID: 27871715 DOI: 10.1016/j.ajodo.2016.04.021
    INTRODUCTION: In this study we aimed to compare measurements on plaster models using a digital caliper, and on 3-dimensional (3D) digital models, produced using a structured-light scanner, using 3D software.

    METHODS: Fifty digital models were scanned from the same plaster models. Arch and tooth size measurements were made by 2 operators, twice. Calibration was done on 10 sets of models and checked using the Pearson correlation coefficient. Data were analyzed by error variances, repeatability coefficient, repeated-measures analysis of variance, and Bland-Altman plots.

    RESULTS: Error variances ranged between 0.001 and 0.044 mm for the digital caliper method, and between 0.002 and 0.054 mm for the 3D software method. Repeated-measures analysis of variance showed small but statistically significant differences (P <0.05) between the repeated measurements in the arch and buccolingual planes (0.011 and 0.008 mm, respectively). There were no statistically significant differences between methods and between operators. Bland-Altman plots showed that the mean biases were close to zero, and the 95% limits of agreement were within ±0.50 mm. Repeatability coefficients for all measurements were similar.

    CONCLUSIONS: Measurements made on models scanned by the 3D structured-light scanner were in good agreement with those made on conventional plaster models and were, therefore, clinically acceptable.

    Matched MeSH terms: Computer Simulation*
  13. Ahamad NA, Kamangar S, Badruddin IA
    Biomed Mater Eng, 2018;29(3):319-332.
    PMID: 29578467 DOI: 10.3233/BME-181734
    The current study investigates the curvature effect due to various angles of curvature on the blood flow in human artery. The stenosis is considered to have three sizes 70%, 80% and 90% blockage before the curve section of artery. Numerical study of four different angle of curvature was considered to understand the flow behavior of artery having various curvatures, on the hemodynamics factors that includes drop in arterial pressure, flow velocity as well as wall shear stress. It was found that, the augmentation of the flow resistance due to the curvature increases in presence of stenosis. It was also noted that the wall shear is higher at the outer wall as compared to the inside wall in four models considered. Results showed that both the curvature of artery and size of the stenosis have significant impact. These two factors should be considered by cardiologist to assess the complexity of stenosis.
    Matched MeSH terms: Computer Simulation*
  14. Moradi F, Ung NM, Khandaker MU, Mahdiraji GA, Saad M, Abdul Malik R, et al.
    Phys Med Biol, 2017 Jul 28;62(16):6550-6566.
    PMID: 28708603 DOI: 10.1088/1361-6560/aa7fe6
    The relatively new treatment modality electronic intraoperative radiotherapy (IORT) is gaining popularity, irradiation being obtained within a surgically produced cavity being delivered via a low-energy x-ray source and spherical applicators, primarily for early stage breast cancer. Due to the spatially dramatic dose-rate fall off with radial distance from the source and effects related to changes in the beam quality of the low keV photon spectra, dosimetric account of the Intrabeam system is rather complex. Skin dose monitoring in IORT is important due to the high dose prescription per treatment fraction. In this study, modeling of the x-ray source and related applicators were performed using the Monte Carlo N-Particle transport code. The dosimetric characteristics of the model were validated against measured data obtained using an ionization chamber and EBT3 film as dosimeters. By using a simulated breast phantom, absorbed doses to the skin for different combinations of applicator size (1.5-5 cm) and treatment depth (0.5-3 cm) were calculated. Simulation results showed overdosing of the skin (>30% of prescribed dose) at a treatment depth of 0.5 cm using applicator sizes larger than 1.5 cm. Skin doses were significantly increased with applicator size, insofar as delivering 12 Gy (60% of the prescribed dose) to skin for the largest sized applicator (5 cm diameter) and treatment depth of 0.5 cm. It is concluded that the recommended 0.5-1 cm distance between the skin and applicator surface does not guarantee skin safety and skin dose is generally more significant in cases with the larger applicators.

    HIGHLIGHTS: • Intrabeam x-ray source and spherical applicators were simulated and skin dose was calculated. • Skin dose for constant skin to applicator distance strongly depends on applicator size. • Use of larger applicators generally results in higher skin dose. • The recommended 0.5-1 cm skin to applicator distance does not guarantee skin safety.

    Matched MeSH terms: Computer Simulation*
  15. Wahab AHA, Saad APM, Syahrom A, Kadir MRA
    Comput Methods Biomech Biomed Engin, 2020 Apr;23(5):182-190.
    PMID: 31910663 DOI: 10.1080/10255842.2019.1709828
    Glenoid perforation is not the intended consequence of the surgery and must be avoided. The analysis on biomechanical aspect of glenoid vault perforation remains unknown. The purpose of this study is to determine the impact of glenoid perforation towards stress distribution and micromotion at the interfaces. Eight glenoid implant models had been constructed with various size, number and type of fixation. A load of 750 N was applied to centre, superior-anterior and superior-posterior area. Implant perforation had minimal impact on stress distribution and micromotion at the interfaces. However, cement survival rate for implant without perforation was the highest with a difference of up to 37% compared to other perforated models. Besides that, implant fixation and high stresses at the implant had more of an impact on implant instability than implant perforation. As a conclusion, glenoid perforation did not influence the stress distribution and micromotion, but, it reduced cement survival rate and increase the stress critical volume.
    Matched MeSH terms: Computer Simulation*
  16. Cheong JKK, Yap S, Ooi ET, Ooi EH
    Comput Methods Programs Biomed, 2019 Jul;176:17-32.
    PMID: 31200904 DOI: 10.1016/j.cmpb.2019.04.028
    BACKGROUND AND OBJECTIVES: Recently, there have been calls for RFA to be implemented in the bipolar mode for cancer treatment due to the benefits it offers over the monopolar mode. These include the ability to prevent skin burns at the grounding pad and to avoid tumour track seeding. The usage of bipolar RFA in clinical practice remains uncommon however, as not many research studies have been carried out on bipolar RFA. As such, there is still uncertainty in understanding the effects of the different RF probe configurations on the treatment outcome of RFA. This paper demonstrates that the electrode lengths have a strong influence on the mechanics of bipolar RFA. The information obtained here may lead to further optimization of the system for subsequent uses in the hospitals.

    METHODS: A 2D model in the axisymmetric coordinates was developed to simulate the electro-thermophysiological responses of the tissue during a single probe bipolar RFA. Two different probe configurations were considered, namely the configuration where the active electrode is longer than the ground and the configuration where the ground electrode is longer than the active. The mathematical model was first verified with an existing experimental study found in the literature.

    RESULTS: Results from the simulations showed that heating is confined only to the region around the shorter electrode, regardless of whether the shorter electrode is the active or the ground. Consequently, thermal coagulation also occurs in the region surrounding the shorter electrode. This opened up the possibility for a better customized treatment through the development of RF probes with adjustable electrode lengths.

    CONCLUSIONS: The electrode length was found to play a significant role on the outcome of single probe bipolar RFA. In particular, the length of the shorter electrode becomes the limiting factor that influences the mechanics of single probe bipolar RFA. Results from this study can be used to further develop and optimize bipolar RFA as an effective and reliable cancer treatment technique.

    Matched MeSH terms: Computer Simulation*
  17. Saleem H, Sarfraz M, Khan KM, Anwar MA, Zengin G, Ahmad I, et al.
    Drug Dev Ind Pharm, 2020 May;46(5):861-868.
    PMID: 32352878 DOI: 10.1080/03639045.2020.1762199
    The biological, chemical, and in silico properties of methanol and dichloromethane (DCM) extracts of Alhagi maurorum roots with respect to the antioxidant, enzyme inhibition, and phytochemical composition were evaluated. Total bioactive contents were determined spectrophotometrically, and the individual secondary metabolites composition was assessed via ultra-high-performance liquid chromatography mass spectrometry (UHPLC-MS) analysis. Antioxidant capacities were evaluated using a panoply of assays (2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) free radical scavenging, ferric reducing antioxidant power (FRAP), cupric reducing antioxidant power (CUPRAC), phosphomolybdenum total antioxidant capacity (TAC), and metal chelating activity (MCA)). The enzyme inhibition potential was studied against acetylcholinesterase (AChE), butyrylcholinesterase (BChE), α-amylase, α-glucosidase, tyrosinase, urease and lipoxygenase (LOX) enzymes. The methanol extract was found to contain higher total phenolic (105.91 mg GAE/g extract) and flavonoid (2.27 mg RE/g extract) contents which can be correlated to its more substantial antioxidant potential as well as AChE, BChE, tyrosinase and α-glucosidase inhibition. However, the DCM extract was the most effective against α-amylase (1.86 mmol ACAE/g extract) enzyme inhibition. The UHPLC-MS analysis of methanol extract identified the tentative presence of a total of 18 secondary metabolites, including flavonoids, saponins, phenolic and terpenoid derivatives. Three compounds named emmotin A, luteolin 5,3'-dimethyl ether, and preferrugone were further investigated for their in silico molecular docking studies against the tested enzymes. The selected compounds were found to have higher binding interaction with AChE followed by BChE, α-glucosidase, α-amylase, and tyrosinase. The results of the present study have demonstrated A. mauroram to be considered as a lead source of natural antioxidant and enzyme inhibitor compounds.
    Matched MeSH terms: Computer Simulation*
  18. Abas ZA, Ramli MR, Desa MI, Saleh N, Hanafiah AN, Aziz N, et al.
    Health Care Manag Sci, 2018 Dec;21(4):573-586.
    PMID: 28822005 DOI: 10.1007/s10729-017-9413-7
    The paper aims to provide an insight into the significance of having a simulation model to forecast the supply of registered nurses for health workforce planning policy using System Dynamics. A model is highly in demand to predict the workforce demand for nurses in the future, which it supports for complete development of a needs-based nurse workforce projection using Malaysia as a case study. The supply model consists of three sub-models to forecast the number of registered nurses for the next 15 years: training model, population model and Full Time Equivalent (FTE) model. In fact, the training model is for predicting the number of newly registered nurses after training is completed. Furthermore, the population model is for indicating the number of registered nurses in the nation and the FTE model is useful for counting the number of registered nurses with direct patient care. Each model is described in detail with the logical connection and mathematical governing equation for accurate forecasting. The supply model is validated using error analysis approach in terms of the root mean square percent error and the Theil inequality statistics, which is mportant for evaluating the simulation results. Moreover, the output of simulation results provides a useful insight for policy makers as a what-if analysis is conducted. Some recommendations are proposed in order to deal with the nursing deficit. It must be noted that the results from the simulation model will be used for the next stage of the Needs-Based Nurse Workforce projection project. The impact of this study is that it provides the ability for greater planning and policy making with better predictions.
    Matched MeSH terms: Computer Simulation*
  19. Adamu A, Wahab RA, Shamsir MS, Aliyu F, Huyop F
    Comput Biol Chem, 2017 Oct;70:125-132.
    PMID: 28873365 DOI: 10.1016/j.compbiolchem.2017.08.007
    The l-2-haloacid dehalogenases (EC 3.8.1.2) specifically cleave carbon-halogen bonds in the L-isomers of halogenated organic acids. These enzymes have potential applications for the bioremediation and synthesis of various industrial products. One such enzyme is DehL, the l-2-haloacid dehalogenase from Rhizobium sp. RC1, which converts the L-isomers of 2-halocarboxylic acids into the corresponding D-hydroxycarboxylic acids. However, its catalytic mechanism has not been delineated, and to enhance its efficiency and utility for environmental and industrial applications, knowledge of its catalytic mechanism, which includes identification of its catalytic residues, is required. Using ab initio fragment molecular orbital calculations, molecular mechanics Poisson-Boltzmann surface area calculations, and classical molecular dynamic simulation of a three-dimensional model of DehL-l-2-chloropropionic acid complex, we predicted the catalytic residues of DehL and propose its catalytic mechanism. We found that when Asp13, Thr17, Met48, Arg51, and His184 were individually replaced with an alanine in silico, a significant decrease in the free energy of binding for the DehL-l-2-chloropropionic acid model complex was seen, indicating the involvement of these residues in catalysis and/or structural integrity of the active site. Furthermore, strong inter-fragment interaction energies calculated for Asp13 and L-2-chloropropionic acid, and for a water molecule and His184, and maintenance of the distances between atoms in the aforementioned pairs during the molecular dynamics run suggest that Asp13 acts as the nucleophile and His184 activates the water involved in DehL catalysis. The results of this study should be important for the rational design of a DehL mutant with improved catalytic efficiency.
    Matched MeSH terms: Computer Simulation*
  20. Kueh R, Rahman NA, Merican AF
    J Mol Model, 2003 Apr;9(2):88-98.
    PMID: 12707802
    The arginine repressor (ArgR) of Escherichia coli binds to six L-arginine molecules that act as its co-repressor in order to bind to DNA. The binding of L-arginine molecules as well as its structural analogues is compared by means of computational docking. A grid-based energy evaluation method combined with a Monte Carlo simulated annealing process was used in the automated docking. For all ligands, the docking procedure proposed more than one binding site in the C-terminal domain of ArgR (ArgRc). Interaction patterns of ArgRc with L-arginine were also observed for L-canavanine and L-citrulline. L-lysine and L-homoarginine, on the other hand, were shown to bind poorly at the binding site. Figure A general overview of the sites found from docking the various ligands into ArgRc ( grey ribbons). Red coloured sticks: residues in binding site H that was selected for docking
    Matched MeSH terms: Computer Simulation*
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