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12 results on '"Teoh G"'

1. Development of resorbable nanocomposite polymers for paediatric airway tissue engineering

Author

Teoh, G. Z., Cousins, B. G., Birchall, M. A., Seifalian, A. M., and Song, W.

Subjects
610.28
Abstract

Advances in stem cell technology, tissue engineering and material sciences have inspired the development of resorbable, nanocomposite polymers for airway tissue engineering. At present, tracheal resection with primary repair is the Gold Standard of care for those with airway disorders; however, the maximum resectable length of the trachea is restricted to 30% of the total length in children. Replacement of longer sections thus requires the development of a safe, functional tracheal prosthesis as there are currently few clinically available options and attempts to provide autologous grafts for human application have been disappointing for a host of different reasons, including lack of integration and poor mechanical strength. Three new ethylene-diethylene glycol based nanocomposite polymers were synthesized and characterized from material and biological perspectives. Material characterization studies included polymer viscosity, tensile strength, suture retention and thromboelastography, in addition to an examination of the degradation profiles. Laminated bilayer polymeric scaffolds were then seeded with human tracheobronchial epithelial cells (HBECs) and bone marrow derived mesenchymal stem cells (bmMSCs) for an in vitro assessment of cytocompatibility before proceeding to in vivo studies examining scaffold integration and vascularization as well as whole construct behavior following orthotropic implantation. In vitro and in vivo results were positive, with key findings including good cell attachment and proliferation, formation of vasculature and a suitable in vivo degradation profile. Overall, a promising material candidate for use in airway tissue engineering has been developed. However, further optimization and standardization of the small diameter tracheal constructs manufactured using POSS-enhanced ethylene-diethylene glycol based polymers is required prior to embarking on pre-clinical and clinical trials exploring the use of the scaffolds for treatment of tracheal anomalies and pathologies in clinics.

Published
2016

5. Combatting Malaysia's Dengue Outbreaks with Auto-Dissemination Mosquito Traps: A Hybrid Stochastic-Deterministic SIR Model

Author

Jonathan Wells, David Greenhalgh, Yanfeng Liang, Itamar Megiddo, Wasi Ahmad Nazni, Teoh Guat-Ney, and Han Lim Lee

Subjects
dengue, auto-dissemination mosquito trap, mosquito home system, aedes mosquitoes, malaysia, sir model, ordinary differential equations, stochastic, deterministic, vector-borne, Biology (General), QH301-705.5, Mathematics, QA1-939
Abstract

Classical mosquito control methods (e.g. chemical fogging) struggle to sustain long-term reductions in mosquito populations to combat vector-borne diseases like dengue. The Mosquito Home System (MHS) is an auto-dissemination mosquito trap, that kills mosquito larvae before they hatch into adult mosquitoes. A novel hybrid stochastic-deterministic model is presented, that successfully predicts the effect of deploying MHSs within high-rise flats in Selangor, Malaysia. Stochastic SIR (Susceptible-Infected-Recovered) equations (flats) are paired with an existing deterministic SIR model (wider Kuala Lumpur population). Model predictions provide excellent agreement with data from a 44 week MHS trial within the flats. The stochastic model is validated as a powerful tool for predicting short- and long-term impacts of deploying this style of trap within similar environments. Significant, sustainable reductions in mosquito populations are predicted when the MHS is active: with a mean of 9 (95% Uncertainty Range (UR): 1; 30) during the 44 week trial period, compared to 35 (95% UR: 1; 234) dengue cases with no MHSs. Long-term predictions for endemic equilibrium show MHSs significantly narrow the mosquito population distribution and reduce dengue prevalence: from a mean of 5 (95% UR: 0; 52) (no MHS), to 1 (95% UR: 0; 8) dengue cases annually (with MHS).

Published
2023
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6. Tracking Dengue Virus Intra-host Genetic Diversity during Human-to-Mosquito Transmission

Author

Sim, S, Aw, PP, Wilm, A, Teoh, G, Hue, KD, Nguyen, NM, Nagarajan, N, Simmons, Cameron, Hibberd, ML, Pimenta, PF, and Pimenta, P

Subjects
Adult, Male, lcsh:Arctic medicine. Tropical medicine, lcsh:RC955-962, viruses, Population, Aedes aegypti, Dengue virus, Viral Nonstructural Proteins, medicine.disease_cause, Polymorphism, Single Nucleotide, Salivary Glands, Dengue fever, Dengue, Young Adult, Aedes, medicine, Animals, Humans, Selection, Genetic, education, Genetics, Genetic diversity, education.field_of_study, biology, lcsh:Public aspects of medicine, Public Health, Environmental and Occupational Health, Genetic Variation, High-Throughput Nucleotide Sequencing, lcsh:RA1-1270, Dengue Virus, biology.organism_classification, medicine.disease, 3. Good health, Gastrointestinal Tract, Infectious Diseases, Viral evolution, RNA, Viral, Female, Horizontal transmission, Research Article
Abstract

Dengue virus (DENV) infection of an individual human or mosquito host produces a dynamic population of closely-related sequences. This intra-host genetic diversity is thought to offer an advantage for arboviruses to adapt as they cycle between two very different host species, but it remains poorly characterized. To track changes in viral intra-host genetic diversity during horizontal transmission, we infected Aedes aegypti mosquitoes by allowing them to feed on DENV2-infected patients. We then performed whole-genome deep-sequencing of human- and matched mosquito-derived DENV samples on the Illumina platform and used a sensitive variant-caller to detect single nucleotide variants (SNVs) within each sample. >90% of SNVs were lost upon transition from human to mosquito, as well as from mosquito abdomen to salivary glands. Levels of viral diversity were maintained, however, by the regeneration of new SNVs at each stage of transmission. We further show that SNVs maintained across transmission stages were transmitted as a unit of two at maximum, suggesting the presence of numerous variant genomes carrying only one or two SNVs each. We also present evidence for differences in selection pressures between human and mosquito hosts, particularly on the structural and NS1 genes. This analysis provides insights into how population drops during transmission shape RNA virus genetic diversity, has direct implications for virus evolution, and illustrates the value of high-coverage, whole-genome next-generation sequencing for understanding viral intra-host genetic diversity., Author Summary Dengue virus (DENV) is transmitted between humans through the bite of infected female Aedes aegypti mosquitoes. Virus populations experience significant drops in size and are subject to differing selection pressures as they cycle between human and mosquito hosts. Subsequent changes in viral intra-host genetic diversity may have consequences for the adaptability and fitness of the virus population as a whole but are poorly understood. To study the impact of human-to-mosquito transmission on DENV populations, we allowed mosquitoes to feed directly on patients with acute dengue infections, then deep-sequenced DENV populations from patient plasma samples and from the abdomens and salivary glands of corresponding mosquitoes. These matched samples allowed us to estimate the size of the population drop that occurs during establishment of infection in the mosquito, track changes in viral intra-host variant repertoires at different stages in transmission, and investigate the possibility of host-specific immune selection pressures acting on the virus population. These novel insights improve our understanding of DENV population dynamics during horizontal transmission.

Published
2015

7. Tracking Dengue Virus Intra-host Genetic Diversity during Human-to-Mosquito Transmission

Author

Pimenta, PF, Sim, S, Aw, PPK, Wilm, A, Teoh, G, Kien, DTH, Nguyet, MN, Nagarajan, N, Simmons, CP, Hibberd, ML, Pimenta, PF, Sim, S, Aw, PPK, Wilm, A, Teoh, G, Kien, DTH, Nguyet, MN, Nagarajan, N, Simmons, CP, and Hibberd, ML

Abstract

Dengue virus (DENV) infection of an individual human or mosquito host produces a dynamic population of closely-related sequences. This intra-host genetic diversity is thought to offer an advantage for arboviruses to adapt as they cycle between two very different host species, but it remains poorly characterized. To track changes in viral intra-host genetic diversity during horizontal transmission, we infected Aedes aegypti mosquitoes by allowing them to feed on DENV2-infected patients. We then performed whole-genome deep-sequencing of human- and matched mosquito-derived DENV samples on the Illumina platform and used a sensitive variant-caller to detect single nucleotide variants (SNVs) within each sample. >90% of SNVs were lost upon transition from human to mosquito, as well as from mosquito abdomen to salivary glands. Levels of viral diversity were maintained, however, by the regeneration of new SNVs at each stage of transmission. We further show that SNVs maintained across transmission stages were transmitted as a unit of two at maximum, suggesting the presence of numerous variant genomes carrying only one or two SNVs each. We also present evidence for differences in selection pressures between human and mosquito hosts, particularly on the structural and NS1 genes. This analysis provides insights into how population drops during transmission shape RNA virus genetic diversity, has direct implications for virus evolution, and illustrates the value of high-coverage, whole-genome next-generation sequencing for understanding viral intra-host genetic diversity.

Published
2015

9. Wide area spray of bacterial larvicide, Bacillus thuringiensis israelensis strain AM65-52, integrated in the national vector control program impacts dengue transmission in an urban township in Sibu district, Sarawak, Malaysia.

Author

Rezal Bohari, Chong Jin Hin, Asmad Matusop, Muhamad Rais Abdullah, Teoh Guat Ney, Seleena Benjamin, and Lee Han Lim

Subjects
Medicine, Science
Abstract

Several sites, Z-7L, Z-5 and Z-14, in Sibu district, Sarawak, Malaysia, experienced intense dengue transmission in 2014 that continued into 2015. A pilot study with Bacillus thuringiensis israelensis (Bti) to control Aedes aegypti (L.) and Ae. albopictus (Skuse) was evaluated in Z-7L, a densely populated site of 12 ha. Bti treatments were conducted weekly from epidemiology week (EW) 24/2015 for 4 weeks, followed by fortnight treatments for 2 months, in addition to the routine control activities. Bti was directly introduced into potable containers and the outdoor artificial and natural containers were treated via a wide area spray application method using a backpack mister. Aedes indices significantly reduced during the treatment and post treatment phases, compared to the control site, Z-5 (p

Published
2020
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12. Role of nanotechnology in development of artificial organs.

Author

Teoh GZ, Klanrit P, Kasimatis M, and Seifalian AM

Subjects
Forecasting, Humans, Nanostructures, Nanotechnology trends, Skin, Artificial, Surface Properties, Artificial Organs, Nanotechnology methods, Tissue Engineering methods
Abstract

Improvements in our understanding of the interactions between implants and cells have directed attention towards nanoscale technologies. To date, nanotechnology has played a helping hand in the development of synthetic artificial organs and regenerative medicine. This includes the production of smart nanocomposite materials; fluorescent nanoparticles like Quantum Dots (QD) and magnetic nano particles (MNP) for stem cell tracking; and carbon nanotubes (CNT) and graphene for enhancement of material properties. The scope of this paper includes the role of nanoparticles in the development of nanomaterials; the chemical surface modifications possible to improve implant function and an overview of the performance of nano-engineered organs thus far. This includes implants developed for aesthetic purposes like nasal and auricular scaffolds, plastic and reconstructive surgical constructs (i.e. dermal grafts), hollow organs for cardiothoracic applications; and last but not least, orthopedic implants. The five-year outlook for nano-enhanced artificial organs is also discussed, highlighting the key research and development areas, available funds and the hurdles we face in accomplishing progression from prototypes on the laboratory bench to off-the-shelf products for the consumer market. Ultimately, this review aims to delineate the advantages of incorporating nanotechnology, as an individual entity or as a part of a construct for the development of tissue engineering scaffolds and/or artificial organs, and unravel the mechanisms of tissue cell-biomaterial interactions at the nanoscale, allowing for better progress in the development and optimization of unique nanoscale surface features for a wide range of applications.

Published
2015

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