Publications by authors named "Yee-Siew Choong"

Article Synopsis
  • Ancylostoma species are parasitic worms that use proteins to manipulate their host's immune system, aiding their survival and potentially making dogs ill with hookworm infections.
  • A specific protein from these worms, called Ancylostoma-secreted protein 5 (ASP5), is crucial for how they interact with their host, making it a good target for treatments.
  • The researchers used a method called antibody phage display to create a monoclonal antibody against ASP5, which was shown to have good binding properties, indicating it could be useful for diagnosing hookworm infections in dogs.
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The rising levels of type 2 diabetes mellitus (T2DM) and the poor medical effects of the commercially available antidiabetic drugs necessitate the development of potent analogs to treat this multifactorial metabolic disorder. It has been demonstrated that targeting two or more biochemical targets associated with the onset and progression of diabetes along with oxidative stress and/or cancer could be a significant strategy for treating complications related to this metabolic disorder. The 3,5-dibromo-4,6-dimethoxychalcones (-) and the corresponding flavone derivatives (-) were synthesized and characterized using spectroscopic (NMR, HR-MS and FT-IR) techniques.

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Article Synopsis
  • Monoclonal antibodies produced using phage display can sometimes have low affinity, making them less useful for applications.
  • To improve their effectiveness, a process called affinity maturation is used, which mimics the natural selection process that occurs in the immune system.
  • This review will explore different strategies for affinity maturation, focusing on various laboratory techniques, including random mutagenesis, site-directed mutagenesis, and gene synthesis.
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Elevated interleukin 8 (IL-8) expression has been linked to unfavorable outcomes in a range of inflammatory conditions, such as rheumatoid arthritis, psoriasis, and cancer. The human monoclonal antibody (HuMab) 10F8 and the hybridoma 35B11-B bind to an epitope on human IL-8, respectively. 10F8 inhibited interaction between IL-8 and neutrophils in eczema and pustulosis palmoplantaris patients while 35B11-B decreased size lesion in rat model.

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Since the advent of hybridoma technology in the year 1975, it took a decade to witness the first approved monoclonal antibody Orthoclone OKT39 (muromonab-CD3) in the year 1986. Since then, continuous strides have been made to engineer antibodies for specific desired effects. The engineering efforts were not confined to only the variable domains of the antibody but also included the fragment crystallizable (Fc) region that influences the immune response and serum half-life.

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Article Synopsis
  • * Antibody phage display is a key technique for isolating human monoclonal antibodies, utilizing bacteriophage to present antibody fragments linked to their genes.
  • * This method enables a selection process that enriches specific binders and allows for further engineering, making it essential for developing and modifying antibodies.
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  • * The proposed method involves fusing a peptide sequence (PEPITEM) with a protein from Mycobacterium tuberculosis (Mtb) α-crystalline (AC) to facilitate the panning of antibodies.
  • * By using this fusion approach along with subtractive selection in the panning process, unique monoclonal antibodies with high specificity against the PEPITEM peptide target were successfully identified.
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  • - Ebola virus causes severe and often fatal hemorrhagic fever, leading to urgent needs for effective diagnosis and treatment, with two monoclonal antibodies approved by the USFDA for EVD.
  • - Research focuses on targeting the Ebola virus protein VP35, which could enhance treatment efforts and has been studied using three isolated mAb clones that bind to it in vitro, demonstrating their potential to inhibit VP35 function.
  • - Structural modeling was performed to analyze how these antibodies interact with VP35, providing insights that could aid in designing new monoclonal antibodies using computational methods in future therapeutic developments.
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The ambident electrophilic character of the 5-bromo-2-hydroxychalcones and the binucleophilic nature of 2-aminothiophenol were exploited to construct the 2-aryl-4-(4-bromo-2-hydroxyphenyl)benzo[1,5]thiazepines. The structures and conformation of these 2-aryl-4-(4-bromo-2-hydroxyphenyl)benzo[1,5]thiazepines were established with the use of spectroscopic techniques complemented with a single crystal X-ray diffraction method. Both H-NMR and IR spectroscopic techniques confirmed participation of the hydroxyl group in the intramolecular hydrogen-bonding interaction with a nitrogen atom.

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The increasing incidence reports of antibiotic resistance highlights the need for alternative approaches to deal with bacterial infections. This brought about the idea of utilizing monoclonal antibodies as an alternative antibacterial treatment. Majority of the studies are focused on developing antibodies to bacterial surface antigens, with little emphasis on antibodies that inhibit the growth mechanisms of a bacteria host.

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The 2-amino-5-(3/4-fluorostyryl)acetophenones were prepared and reacted with benzaldehyde derivatives to afford the corresponding 5-styryl-2-aminochalcone hybrids. The geometry of the styryl and α,β-unsaturated carbonyl arms, and the presence of NHO intramolecular hydrogen bond were validated using H-NMR and X-ray data. The 2-amino-5-styrylacetophenones and their 5-styryl-2-aminochalcone derivatives were screened in vitro for their capability to inhibit α-glucosidase and/or α-amylase activities.

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The 2-aryl-2,3-dihydrobenzodiazaborinin-4(1H)-ones (azaborininone) were synthesized as analogues of the 2-arylquinazoline-4-ones and screened through enzymatic assay in vitro for inhibitory effect against α-glucosidase and α-amylase activities. These azaborininones exhibited moderate to good inhibitory effect against these enzymes compared to acarbose used as a reference standard. The results are supported by the enzyme-ligand interactions through kinetics (in vitro) and molecular docking (in silico) studies.

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The murine double minute 2 (MDM2) protein is a major negative regulator of the tumour suppressor protein p53. Under normal conditions, MDM2 constantly binds to p53 transactivation domain and/or ubiquinates p53 via its role as E3 ubiquitin ligase to promote p53 degradation as well as nuclear export to maintain p53 levels in cells. Meanwhile, amplification of MDM2 and appearance of MDM2 spliced variants occur in many tumours and normal tissues making it a prognostic indicator for human cancers.

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Purpose: Diabetes mellitus is a common condition in the clinically obese. Bariatric surgery is one of the ways to put type 2 diabetes in remission. Recent findings propose the appetite-regulator peptide tyrosine tyrosine (PYY) as a therapeutic option for patients with type 2 diabetes.

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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.

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Antibodies have different chemical properties capable of targeting a diverse nature of antigens. Traditionally, immune antibody libraries are perceived to be disease-specific with a skewed repertoire. The complexity during the generation of a combinatorial antibody library allows for a skewed but diverse repertoire to be generated.

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Leptospirosis is a potentially fatal zoonosis that is caused by spirochete Leptospira. The signs and symptoms of leptospirosis are usually varied, allowing it to be mistaken for other causes of acute febrile syndromes. Thus, early diagnosis and identification of a specific agent in clinical samples is crucial for effective treatment.

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Lipids, glycolipids and lipopeptides derived from (Mtb) are presented to T cells by monomorphic molecules known as CD1. This is the case of the Mtb-specific sulfoglycolipid AcSGL, which is presented by CD1b molecules and is recognized by T cells found in tuberculosis (TB) patients and in individuals with latent infections. Our group, using filamentous phage display technology, obtained two specific ligands against the CD1b-AcSGL complex: (i) a single chain T cell receptor (scTCR) from a human T cell clone recognizing the CD1b-AcSGL complex; and (ii) a light chain domain antibody (dAbκ11).

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Pulmonary tuberculosis, caused by Mycobacterium tuberculosis, is one of the most persistent diseases leading to death in humans. As one of the key targets during the latent/dormant stage of M. tuberculosis, isocitrate lyase (ICL) has been a subject of interest for new tuberculosis therapeutics.

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Nucleic acids have special ability to organize themselves into various non-canonical structures, including a four-stranded DNA structure termed G-quadruplex (G4) that has been utilized for diagnostic and therapeutic applications. Herein, we report the ability of G4 to distinguish dengue virus (DENV) based on its serotypes (DENV-1, DENV-2, DENV-3 and DENV-4) using a split G4-hemin DNAzyme configuration. In this system, two separate G-rich oligonucleotides are brought together upon target DNA strand hybridization to form a three-way junction architecture, allowing the formation of a G4 structure.

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A series of furocoumarin-stilbene hybrids has been synthesized and evaluated in vitro for inhibitory effect against acetylcholinesterase (AChE), butyrylcholinestarase (BChE), β-secretase, cyclooxygenase-2 (COX-2), and lipoxygenase-5 (LOX-5) activities including free radical-scavenging properties. Among these hybrids, 8-(3,5-dimethoxyphenyl)-4-(3,5-dimethoxystyryl)furochromen-2-one 4h exhibited significant anticholinesterase activity and inhibitory effect against β-secretase, COX-2 and LOX-5 activities. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and an in vitro cell-based antioxidant activity assay involving lipopolysaccharide induced reactive oxygen species production revealed that 4h has capability of scavenging free radicals.

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The binding of IgG Fc with FcRn enables the long circulating half-life of IgG, where the Fc-FcRn complex interacts in a pH-dependent manner. This complex shows stronger interaction at pH ≤ 6.5 and weaker interaction at pH ≥ 7.

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The 5-acetyl-2-aryl-6-hydroxybenzo[]furans - have been evaluated through in vitro enzymatic assay against targets which are linked to type 2 diabetes (T2D), namely, α-glucosidase, protein tyrosine phosphatase 1B (PTP1B) and β-secretase. These compounds have also been evaluated for antioxidant activity using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free-radical scavenging method. The most active compounds against α-glucosidase and/or PTP1B, namely, 4-fluorophenyl , 4-methoxyphenyl and 3,5-dimethoxyphenyl substituted derivatives were also evaluated for potential anti-inflammatory properties against cyclooxygenase-2 activity.

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