19672 research outputs found
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Evaluation of Ge-doped silica fibre TLDs forin vivodosimetry during intraoperative radiotherapy
No full textGe-doped silica fibre (GDSF) thermoluminescence dosimeters (TLD) are non-hygroscopic spatially high-resolution radiation sensors with demonstrated potential for radiotherapy dosimetry applications. The INTRABEAM® system with spherical applicators, one of a number of recent electronic brachytherapy sources designed for intraoperative radiotherapy (IORT), presents a representative challenging dosimetry situation, with a low keV photon beam and a desired rapid dose-rate fall-off close-up to the applicator surface. In this study, using the INTRABEAM® system, investigations were made into the potential application of GDSF TLDs for in vivo IORT dosimetry. The GDSFs were calibrated over the respective dose- and depth-range 1 to 20 Gy and 3 to 45 mm from the x-ray probe. The effect of different sizes of spherical applicator on TL response of the fibres was also investigated. The results show the GDSF TLDs to be applicable for IORT dose assessment, with the important incorporated correction for beam quality effects using different spherical applicator sizes. The total uncertainty in use of this type of GDSF for dosimetry has been found to range between 9.5% to 12.4%. Subsequent in vivo measurement of skin dose for three breast patients undergoing IORT were performed, the measured doses being below the tolerance level for acute radiation toxicity. © 2019 Institute of Physics and Engineering in Medicine
Amino acid signatures of HLA Class-I and II molecules are strongly associated with SLE susceptibility and autoantibody production in Eastern Asians
No full textHuman leukocyte antigen (HLA) is a key genetic factor conferring risk of systemic lupus erythematosus (SLE), but precise independent localization of HLA effects is extremely challenging. As a result, the contribution of specific HLA alleles and amino-acid residues to the overall risk of SLE and to risk of specific autoantibodies are far from completely understood. Here, we dissected (a) overall SLE association signals across HLA, (b) HLA-peptide interaction, and (c) residue-autoantibody association. Classical alleles, SNPs, and amino-acid residues of eight HLA genes were imputed across 4,915 SLE cases and 13,513 controls from Eastern Asia. We performed association followed by conditional analysis across HLA, assessing both overall SLE risk and risk of autoantibody production. DR15 alleles HLADRB1*15:01 (P = 1.4x10-27, odds ratio (OR) = 1.57) and HLA-DQB1*06:02 (P = 7.4x10-23, OR = 1.55) formed the most significant haplotype (OR = 2.33). Conditioned protein-residue signals were stronger than allele signals and mapped predominantly to HLA-DRB1 residue 13 (P = 2.2x10-75) and its proxy position 11 (P = 1.1x10-67), followed by HLA-DRB1-37 (P = 4.5x10-24). After conditioning on HLA-DRB1, novel associations at HLA-A-70 (P = 1.4x10-8), HLA-DPB1-35 (P = 9.0x10-16), HLA-DQB1-37 (P = 2.7x10-14), and HLA-B-9 (P = 6.5x10-15) emerged. Together, these seven residues increased the proportion of explained heritability due to HLA to 2.6%. Risk residues for both overall disease and hallmark autoantibodies (i.e., nRNP: DRB1-11, P = 2.0x10-14; DRB1-13, P = 2.9x10-13; DRB1-30, P = 3.9x10-14) localized to the peptide-binding groove of HLA-DRB1. Enrichment for specific amino-acid characteristics in the peptide-binding groove correlated with overall SLE risk and with autoantibody presence. Risk residues were in primarily negatively charged side-chains, in contrast with rheumatoid arthritis. We identified novel SLE signals in HLA Class I loci (HLA-A, HLA-B), and localized primary Class II signals to five residues in HLA-DRB1, HLA-DPB1, and HLADQB1. These findings provide insights about the mechanisms by which the risk residues interact with each other to produce autoantibodies and are involved in SLE pathophysiology. © 2019 Molineros 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
Reference ranges for d-dimer levels in malaysian women in the three trimesters of pregnancy
No full textIntroduction: Plasma D-dimer levels rise progressively during pregnancy, so one cannot apply normal reference ranges, or the usual cut-off value (500ng/mL), for the exclusion of venous thromboembolism (VTE), in pregnant women. This study was carried out in pregnant Malaysian women in order to build applicable reference ranges for D-dimer. Materials and Methods: A cross-sectional study was conducted to measure D-dimer in healthy pregnant women, and a non-pregnant control group, using the quantitative HaemosIL D-dimer HS500 assay. Reference ranges were derived using CLSI ‘Robust’ methods, and differences between group medians were tested using the Kruskal-Wallis and Mann-Whitney U tests. Results: Plasma D-dimer levels were measured in 92 pregnant women (distributed across the three trimesters)and 31 control women. The medians (and reference ranges) in ng/mL were: Control 265 (<799); first trimester 481 (<1070); second trimester 1073 (357–1748); 3rd trimester 1533 (771–2410). There were significant differences between the D-dimer levels of each group and each of the other groups (P<0.001). Conclusions: Reference ranges for D-dimer in pregnant Malaysian women have been establised by this study. Whether these ranges can be used to determine cut-off levels for the exclusion of VTE at different stages of pregnancy is doubtful, as the levels rise continuously through pregnancy, and some very high outlying values occur in apparently normal near-term pregnancy. © 2019, Malaysian Society of Pathologists. All rights reserved
Improving knowledge of doctors and paramedics through effective bone procurement workshop: A cognitive approach
No full textBackground: Procurement of bone allograft must be performed by trained personnel. Improper handling and lack of knowledge during bone procurement will lead to contamination hence jeopardizing quality of the procured bones and expose bone recipients to risks of infection in post-operative phase. Bone procurement workshop is the fundamental training programme to enhance skill among personnel who has been or will be involved in bone procurement. This study evaluated the effectiveness of the workshop contents including teaching materials by assessing the knowledge on bone procurement among the participants before and after the workshop. Methods: Bone procurement workshop was held for 2 days for doctors and paramedics. The knowledge on bone procurement was evaluated in pre- and post-assessments by answering self administration questionnaire before and after the workshop, respectively. Results: A total of 50 participants comprised of doctors and paramedics attended the workshop however only 15 (55.6%) doctors and 12 (44.4%) paramedics completed the assessments. Overall, the mean total score for the post-assessment (61.4%) was significantly higher (p < 0.05) than that of the pre-assessment score (32.2%). The mean values of correct responses for the post-assessment was significantly higher (p < 0.05) than that of the pre-assessment in all five topics given during the workshop. The correct responses for the pre- and the post- assessments in the respective group of the doctors and paramedics were also statistically significant (p < 0.05). In the pre-assessment, the doctors had the highest score in Surgical Approach & Reconstruction (50%) while the paramedics had the highest score in Donor Screening & Selection Criteria (33.3%). In the post-assessment, the doctors had the highest score in Donor Screening & Selection Criteria (70%) while the paramedics in Packaging & Transportation (65.8%). Conclusions: The assessment managed to show that the workshop contents and teaching materials were effective in improving the cognitive knowledge of the personnel who would get involved in bone procurement under the National Donation Programme. © 2019 The Author(s)
Recoverability of Fe3O4/TiO2 nanocatalyst in methyl orange degradation
No full textIron oxide/titania (Fe3O4/TiO2) magnetic nanocatalysts approximately 30 nm in size were synthesized by co-precipitation method. The structure and morphology of the prepared nanocatalyst were characterized by Field Emission Scanning Electron Microscope coupled with Energy Dispersive X-ray spectroscopy (FESEM-EDX), Transmission Electron Microscope (TEM), Fourier Transform Infrared Spectroscopy (FT-IR), X-ray Diffraction (XRD), Raman Spectroscopy, UV Diffuse Reflectance Spectroscopy (UV-DRS), Vibrating Sample Magnetometer (VSM), and Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) analyses. The prepared nanocatalyst showed good photocatalytic activity for the degradation of methyl orange (MO) dye solution. The Fe3O4/TiO2 (P25) showed better photocatalytic ability compared to that of Fe3O4/TiO2 (UV100) for MO dye degradation (10 ppm) under UV irradiation (λ = 254 nm). The experimental results revealed that 90.3% of MO dye was degraded with Fe3O4/TiO2 (P25) nanocatalyst, as compared to Fe3O4/TiO2 (UV100) nanocatalyst with only 51.6% after 1 h irradiation. The synthesized magnetic nanocatalysts are stable up to 5 cycles due to their strong recoverability towards an external magnet. Interestingly, the nanocatalyst was reasonably stable after being left undisturbed for 12 months. © 2019 IOP Publishing Ltd
Rheological behaviour of thermotropic and lyotropic liquid crystalline phases of Guerbet branched chain glycolipids
No full textGlycolipids, being low toxicity, biodegradable and showing surface activity, are a candidate for an alternative surfactant known as biosurfactant. In this study, two Guerbet branched chain glycolipids namely 2-hexyl-decyl-β-D-glucoside (β-Glc-C10C6) and 2-hexyl-decyl-β-D-maltoside (β-Mal-C10C6) were prepared and their mesomorphic behaviours in dry and hydrated conditions were characterized and compared using rheology. These glycolipids possessed the same number of carbons in their alkyl chain but differed in headgroup size. β-Glc-C10C6 exhibited inverse hexagonal phase (H2) in thermotropic but formed inverse bicontinuous cubic phase (V2) of space group Ia3d and Pn3m upon contact with water at different concentration ranges. The self-assembly of β-Mal-C10C6 was dominated by the lamellar phase (Lα) in both conditions. A shear viscosity test indicated that all mesophases formed by these Guerbet glycolipids exhibited shear thinning behaviour. Oscillation measurements were obtained within the linear viscoelastic regime. In general, the viscoelastic studies on the thermotropic H2 (β-Glc-C10C6) and Lα (β-Mal-C10C6) phases showed that the storage modulus (G′) and loss modulus (G″) increased with the frequency, indicating the typical viscoelastic response for non-Newtonian fluid at the selected temperatures. The lyotropic inverse bicontinuous cubic of β-Glc-C10C6 containing different water concentrations showed the dominance of G’ over G” at the range of frequencies and temperatures tested. A similar finding was observed for the lyotropic Lα phase of β-Mal-C10C6 but with a lower magnitude of structural strength. © 2019 Elsevier B.V
Ventilation blocks: Design feature in Malaysia public schools
No full textHot and humid climate conditions have always been a challenge to building designers in tropical countries. Mouldy façade can emerge within a few days due to heavy rain and a room can easily become hot and musty. These are among the major issues caused by improper ventilation. To overcome these problems, ventilation block, an ingenious building element that has a long history, is widely used in tropical countries. It provides comfort through cross ventilation, permitting daylight and offering protection from heavy rainfall and, giving aesthetic value. This paper is part of the main research on the findings of passive design elements in Malaysia schools buildings. The main purpose of this paper is to investigate, identify and discuss on the types, the design features and the characteristics of the ventilation blocks found on the existing primary school buildings in Kuala Lumpur territory, Malaysia. A total of 85 from a list of 201 schools were visited and observation was made. The schools were selected and categorised according to the years they were founded and based on the findings of their architectural design influences. It was found that there were at least 10 different ventilation block designs among the schools sampled in the present study which were built between the 1950s and 1960s. This element can be found in various locations of the buildings. Nevertheless, the purpose of such element was clearly to provide good ventilation and comfort to the occupants. Combining architecture and cross ventilation as a design feature has led to the implication of using ventilation block may not only solve the problems identified but also add value to the building and a present a convincing strategy towards sustainable design approach. © 2019, University of Malaya. All rights reserved
Synthesis and evaluation of the structural, optical, and antibacterial properties of copper oxide nanoparticles
No full textThe nanostructured material, due to their outstanding applications in various fields of science and technology; metal and metal oxide nano are exclusively explored in the progress of nanosized materials. The transition metal oxides including CuO is are used for magnetic storage devices, solar energy applications, sensors, as a catalyst in reactions, as electrode materials in supercapacitors and to tune the semiconducting properties of materials. The current work focuses on the synthesis of CuO nanoparticles (NPs) by combustion technique for various annealing (100°C and 300°C) using ascorbic acid as a capping agent. The XRD pattern confirms that the CuO NPs exhibit the monoclinic structure. The optical properties are investigated using UV–Vis absorption spectra. Further, the refractive index, optical dielectric constant and bulk modulus were investigated using the specific empirical model as a function of temperature. The FTIR spectrum shows that the band in the range 450–500 cm−1 confirms the formation of CuO NPs. The SEM images revealed that the spherical surface morphology of the CuO NPs. The Elemental analysis and the particle size were confirmed by elemental dispersive X-ray analysis (EDX) and particle size analyzer. Moreover, the antibacterial activity of CuO nanoparticles was investigated using E. coli, S. typhi, M. luteus, P. fluorescent, S. flexneri, and V. cholera bacteria. © 2019, Springer-Verlag GmbH Germany, part of Springer Nature
Muscle Size and Strength Benefits of Functional Electrical Stimulation-Evoked Cycling Dosage in Spinal Cord Injury: A Narrative Review
No full textLoss of sensory motor function is one of the main causes of physical and activity limitations among individual with spinal cord injury (SCI). SCI may lead to muscle paralysis, weakness and disused muscle atrophy. Evidences have shown electrical stimulation and strengthening exercise might improve lower limb muscle strength and size among individual with SCI. Functional electrical stimulation (FES) evoked cycling is one of the methods that can elicit leg muscle contractions in order to produce a cycling motion and promote the integrity of the involved muscles. Therefore, this review is to synthesize the scientific literature regarding the effects of multiple dosages of FES-evoked lower limb cycling on muscle properties. A systematic literature search from 1946 to 2016 was performed. From over 1,139 articles retrieved from the database, about 31 potentially relevant articles were retained for possible inclusion. However, only 10 articles out of 31 articles fulfilled the inclusion criteria. Although the available evidence is compelling, there is insufficient quantity and quality evidence to draw conclusions regarding the specific parameter of FES-CE that may optimally increase muscle strength, mass, and circumference. However, it can be safely concluded that an effective training session would spend for 45-60 min, 3 times a week for at least 4 weeks to see changes in muscle size and strength. © 2019 Penerbit Universiti Kebangsaan Malaysia. All rights reserved
Biophysical and computational approaches to unravel the molecular interaction mechanism of bromodeoxyuridine, a proliferative marker with human serum albumin
No full textAbstract: The interaction of a nucleoside analogue bromodeoxyuridine (BrdU) with human serum albumin (HSA) was studied to investigate the binding phenomenon and analyse the protein conformation upon BrdU binding. Multiple spectroscopic techniques, viz. intrinsic and 3-D fluorescence, UV–Vis absorption, and circular dichroism (CD) spectroscopy along with molecular docking were used. Decrease in the Stern–Volmer constant (Ksv) as well as the association constant (Ka) with increase in temperature suggested BrdU–HSA complex formation. Intermediate binding affinity between BrdU and HSA was evident from the Ka values (2.49–3.97 × 104 mol–1 dm3), while BrdU–HSA complex formation was driven by hydrophobic and van der Waals interactions along with hydrogen bonds, as revealed by thermodynamic data (ΔS = + 28.48 J mol−1 K−1; ΔH = − 17.16 kJ mol−1). Minor changes occur in both secondary and tertiary structures as well as in the fluorophores’ microenvironment of HSA, as recognized from the CD spectral results in the far-UV and the near-UV regions and 3-D fluorescence spectra, respectively. Use of site markers (warfarin and indomethacin for site I; diazepam for site II) as well as docking results suggested BrdU binding to both site I (more preferred) and site II, located in subdomains IIA and IIIA, respectively, of HSA. Graphic abstract: [Figure not available: see fulltext.]. © 2019, Springer-Verlag GmbH Austria, part of Springer Nature