Preliminary investigations on an enzyme immobilized optical biosensor for arsenite detection

Arsenite is an inorganic form of arsenic that poses hazardous effect to human. It is a common environmental heavy metal contaminant ubiquitously found in water and groundwater. In this study, an optical biosensor for arsenite determination was developed by immobilization of crude arsenite oxidase (Aio) extracted from recombinant E. coli, in chitosan solution coated on triacetyl-cellulose membrane employing DCPIP as colour indicator. The arsenite oxidase (Aio) was successfully expressed and extracted from recombinant E. coli strain BL21 (DE3). The protein concentration and specific activity of the crude arsenite oxidase were determined. Expression of Aio was confirmed by SDS-PAGE. The crude Aio was also successfully immobilized in chitosan and coated on triacetyl cellulose membrane. The response time and dynamic range of the optical biosensor were optimized. The response time of the developed biosensor was 15 minutes. The amount of DCPIP reduced (ΔA) was inversely proportional to the arsenite concentration. Standard calibration curve for arsenite detection was achieved within the range of arsenite concentration from 25 μM to 200 μM. The maximum detection limit was determined to be 250 μM arsenite

Targeted rescue of cancer-associated IDH1 mutant activity using an engineered synthetic antibody

We have utilized a high-diversity phage display library to engineer antibody fragments (Fabs) that can modulate the activity of the enzyme isocitrate dehydrogenase 1 (IDH1). We show that a conformation-specific Fab can reactivate an IDH1 mutant associated with brain tumors. The results show that this strategy is a first step towards developing "activator drugs" for a large number of genetic disorders where mutations have disrupted protein function

Draft genome sequence of arsenic- resistant Microbacterium sp. strain SZ1 isolated from arsenic-bearing gold ores

Microbacterium sp. strain SZ1 isolated from gold ores of a Malaysia gold mine was found to be highly resistant to arsenic. Here, we report the draft genome sequence of SZ1, which may provide further insights into understanding its arsenic resistance mechanism. In this draft genome, a complete set of ars operons and two additional scattered ars genes were encoded

Cotrimoxazole-induced SIADH — a unique challenge during treatment of pulmonary nocardiosis

A 62 year old male non-smoker diagnosed with pulmonary nocardiosis was initiated on Cotrimoxazole therapy at a dose of 20 mg/kg per day in three divided doses. He developed hyponatremia (serum sodium 105 mEq/L) on day 3 of therapy. The potential causes of hyponatremia were evaluated. After ruling out other causes, the cause was suspected to be Cotrimoxazole-induced syndrome of inappropriate anti-diuretic hormone secretion (SIADH). We subsequently re-initiated therapy with Cotrimoxazole and the hyponatremia (serum sodium 110 mEq/L) recurred. Upon discontinuation of therapy, serum sodium levels returned to normal. The patient was started on Amoxycillin-Clavulanic Acid as an alternative therapy for pulmonary nocardiosis which resulted in resolution of the hyponatremia. Cotrimoxazole-induced SIADH is a rare occurrence. This case is representative of a patient with Cotrimoxazole-induced SIADH and the causal relationship was confirmed once resumption of therapy with the offending medi-cation resulted in hyponatremia. Clinicians should be aware of this rare adverse effect of Cotrimoxazole and should monitor serum electrolytes during therapy, especially in the elderly and in those receiving high doses

Identification of a Novel Cysteine-stack Arrangement in Parallel β-helix Proteins using Computational and Knowledge-based Approach

Abstract Parallel β-helices, a subclass of β-sheet proteins, represent the folding of a polypeptide chain into an elongated topologically simpler fold than globular β-sheets. However, the amino acid sequence rules that specify β-sheet structure in protein remain unelucidated. In this study, a combination of knowledge-based and computational analysis using the novel cysteine staple pattern found in pectin methylesterase A to predict the right-handed parallel β-helix structural motif in primary amino acid sequences is presented. The novel staple pattern was used to find further pectin lyase-like protein families displaying this pattern, and to produce high confidence 3D models for all detectable members of this superfamily. To achieve these goals, candidate sequences were retrieved from GenPept and SUPERFAMILY databases. Possible pectin lyase-like proteins were detected with two different fold recognition algorithms, and stringent criteria were designed to minimise false positive predictions. The filtered datasets were clustered, resulting into two main categories; Category A included all sequences with homologues in the PDB and Category B comprised all sequences with unknown homologues. Four families have been identified as new family, where prior to this study, the proteins in this new family had not been identified nor classified as pectin lyase-like proteins. Multiple sequence alignments were generated from each family in both categories, and were carefully inspected to finally produce highly accurate alignments to be used as input for large-scale automatic modeling. There were 298 high quality 3D models of pectin lyase-like proteins produced, which may be used to provide a valuable resource for biological research in this area. Models inspection has revealed numerous instances of possible cysteine stacks in the β-helix cores, where asparagine ladders are common as well as the existence of disulphide bridges

StereoTactic radiotherapy for wet Age-Related macular degeneration (STAR):Study protocol for a randomized controlled clinical trial

BACKGROUND: The standard of care for neovascular age-related macular degeneration (nAMD) involves ongoing intravitreal injections of anti-angiogenic drugs targeting vascular endothelial growth factor (VEGF). The most commonly used anti-VEGF drugs are ranibizumab, bevacizumab and aflibercept. The main objective of the STAR trial is to determine if stereotactic radiotherapy can reduce the number of anti-VEGF injections that patients with nAMD require. METHODS/DESIGN: STAR is a multicentre, double-masked, randomised, sham-controlled clinical trial. It evaluates a new device (manufactured by Oraya, Newark, CA, USA) designed to deliver stereotactic radiotherapy (SRT) to nAMD lesions. The trial enrols participants with chronic, active nAMD. Participants receive a single SRT treatment (16 Gy or sham) with a concomitant baseline intravitreal injection of 0.5 mg ranibizumab. Thereafter, they attend every month for 24 months, and ranibizumab is administered at the visit if retreatment criteria are met. The primary outcome is the number of pro re nata ranibizumab injections during the first 24 months. Secondary outcomes include visual acuity, lesion morphology, quality of life and safety. Additional visits occur at 36 and 48 months to inspect for radiation retinopathy. The target sample size of 411 participants (randomised 2:1 in favour of radiation) is designed to detect a reduction of 2.5 injections against ranibizumab monotherapy, at 90% power, and a significance level (alpha) of 0.025 (one-sided two-sample t test). This gives 97% power to detect non-inferiority of visual acuity at a five-letter margin. The primary analyses will be by intention to treat. DISCUSSION: The safety and efficacy outcomes will help determine the role of SRT in the management of chronic, active nAMD. TRIAL REGISTRATION: International Standard Randomised Controlled Trial Number: ISRCTN12884465. Registered on 28 November 2014. ClinicalTrials.gov: NCT02243878. Registered on 17 September 2014

Characterization of bionanocellulose producing bacteria isolated from tapioca wastewater

This study was conducted to explore the potential of isolating bionanocellulose (BNC) producing bacteria from tapioca wastewater. A total of ten bacteria were successfully isolated and only one isolate named BPNC 3 produced white gelatinous materials in Hestrin and Schramm (HS) medium believed to be the BNC. According to 16S rRNA analysis, bacterium BPNC 3 was identified as Asaia sp. The BNC produced by Asaia sp. BPNC3 was characterized via Fourier transformed-infrared spectroscopy (FTIR) and Field-emission scanning electron microscope (FESEM). The FTIR spectrum showed the presence of two signature peaks at 3276.69 cm-1 and 2923.99 cm-1 indicative of nanocellulosic material. The FESEM micrograph showed characteristics of network fibrils typically present in nanocellulose structure

Rotary Ultrasonic Assisted Machining Of Mould And Die Material

The high strength properties of hardened steel AISI D2 material (~51 HRc) have created problems to the conventional machining process; poor machined surface, high cutting force, extreme machining temperature and rapid tool wear. In order to solve the discrepancies in machining the material, this paper proposed a hybrid machining process technique that combined a high frequency ultrasonic vibration (~20 kHz) with the rotating end mill. An in-house ultrasonic tool holder that fitted the CNC machine spindle was developed to perform the ultrasonic assisted machining process. A set of experimental work was conducted to evaluate the improvement of the ultrasonic vibration in the cutting process. The evaluation included the effects of machining parameter namely cutting speed, feed rate, depth of cut, ultrasonic frequency and vibration amplitude in improving the surface roughness value for machining hardened AISI D2 material. The analytical results demonstrated that the presence of the ultrasonic vibration was able to improve the machined surface roughness in that up to 80% reduction in Ra value was observed as compared to the conventional machining process within the same cutting conditions

Statistical Analysis On The Effect Of Machining Conditions Towards Surface Finish During Edge Trimming Of Carbon Fiber Reinforced Plastics (CFRP)

The main aim of this work was to investigate the effect of machining conditions namely cutting speed (Vc) and feed per tooth (fz) towards the surface finish during the edge trimming process on a specific CFRP material. The range of cutting speed (Vc) applied was 50m/min (low), 100 m/min (middle) and 150 m/min (high) whilst for the feed per tooth (fz); 0.05 mm (low), 0.10 mm (middle) and 0.15 mm (high). The CFRP panel is measured 3.25 mm in thickness and has 28 plies in total. Router or burr tool made of uncoated tungsten carbide with a diameter of 6.35 mm is used to perform the edge trimming process. The Taguchi technique has been adopted to plan the overall experimental process. Surface roughness measurement was taken using Mitutoyo Surftest SJ-410 and optical microscope Nikon MM-800 is utilized to further observe the quality of the trimmed surfaces. From the ANOVA analysis, both factors namely cutting speed, Vc and feed per tooth, fz indicated a significant result towards the surface finish of the trimmed surfaces. The result is supported by the observation via optical microscopy which clearly exhibits uncut fibers, fiber pull-out and matrix degradation conditions. Detailed results are elaborated and discussed further in this paper

Merging cloned alloy models with colorful refactorings

Likewise to code, clone-and-own is a common way to create variants of a model, to explore the impact of different features while exploring the design of a software system. Previously, we have introduced Colorful Alloy, an extension of the popular Alloy language and toolkit to support feature-oriented design, where model elements can be annotated with feature expressions and further highlighted with different colors to ease understanding. In this paper we propose a catalog of refactorings for Colorful Alloy models, and show how they can be used to iteratively merge cloned Alloy models into a single feature-annotated colorful model, where the commonalities and differences between the different clones are easily perceived, and more efficient aggregated analyses can be performed.This work is financed by the ERDF — European Regional Development Fund through the Operational Programme for Competitiveness and Internationalisation – COMPETE 2020 Programme and by National Funds through the Portuguese funding agency, FCT – Fundação para a Ciência e a Tecnologia within project PTDC/CCI-INF/29583/2017 – POCI-01-0145-FEDER-029583