17 results on '"De Silva K"'
Search Results
2. Validation and calibration of a novel GEM biosensor for specific detection of Cd2+, Zn2+, and Pb2+
- Author
-
Herath, H. M. L. P. B., de Silva, W. R. M., Dassanayake, R. S., Gunawardene, Y. I. N. S., Jayasingha, J. R. P., Gayashan, M. K., Afonso, L. O. B., and de Silva, K. M. N.
- Published
- 2023
- Full Text
- View/download PDF
3. Validation and calibration of a novel GEM biosensor for specific detection of Cd2+, Zn2+, and Pb2+.
- Author
-
Herath, H. M. L. P. B., de Silva, W. R. M., Dassanayake, R. S., Gunawardene, Y. I. N. S., Jayasingha, J. R. P., Gayashan, M. K., Afonso, L. O. B., and de Silva, K. M. N.
- Subjects
BIOSENSORS ,HEAVY metals ,GREEN fluorescent protein ,GENE regulatory networks ,ESCHERICHIA coli ,REPORTER genes ,LOGIC circuits - Abstract
Background: In this study, we designed a novel genetic circuit sensitive to Cd
2+ , Zn2+ and Pb2+ by mimicking the CadA/CadR operon system mediated heavy metal homeostasis mechanism of Pseudomonas aeruginosa. The regular DNA motifs on natural operon were reconfigured and coupled with the enhanced Green Fluorescent Protein (eGFP) reporter to develop a novel basic NOT type logic gate CadA/CadR-eGFP to respond metal ions mentioned above. A Genetically Engineered Microbial (GEM)-based biosensor (E.coli-BL21:pJET1.2-CadA/CadR-eGFP) was developed by cloning the chemically synthesised CadA/CadR-eGFP gene circuit into pJET1.2-plasmid and transforming into Escherichia coli (E. coli)-BL21 bacterial cells. Results: The GEM-based biosensor cells indicated the reporter gene expression in the presence of Cd2+ , Zn2+ and Pb2+ either singly or in combination. Further, the same biosensor cells calibrated for fluorescent intensity against heavy metal concentration generated linear graphs for Cd2+ , Zn2+ and Pb2+ with the R2 values of 0.9809, 0.9761 and 0.9758, respectively as compared to non-specific metals, Fe3+ (0.0373), AsO4 3− (0.3825) and Ni2+ (0.8498) making our biosensor suitable for the detection of low concentration of the former metal ions in the range of 1–6 ppb. Furthermore, the GEM based biosensor cells were growing naturally within the concentration range of heavy metals, at 37 °C and optimum pH = 7.0 in the medium, resembling the characteristics of wildtype E.coli. Conclusion: Finally, the novel GEM based biosensor cells developed in this study can be applied for detection of targeted heavy metals in low concentration ranges (1–6 ppb) at normal bacterial physiological conditions. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
4. Use of nanotechnology for infectious disease diagnostics: application in drug resistant tuberculosis
- Author
-
Karunaratne, Roshanthi Eranga, Wijenayaka, Lahiru A., Wijesundera, Sandya Sulochana, De Silva, K. M. Nalin, Adikaram, Chamila Priyangani, and Perera, Jennifer
- Published
- 2019
- Full Text
- View/download PDF
5. Case definition terminology for paratuberculosis (Johne’s disease).
- Author
-
Whittington, R. J., Begg, D. J., de Silva, K., Purdie, A. C., Dhand, N. K., and Plain, K. M.
- Abstract
Paratuberculosis (Johne’s disease) is an economically significant condition caused by Mycobacterium avium subsp. paratuberculosis. However, difficulties in diagnosis and classification of individual animals with the condition have hampered research and impeded efforts to halt its progressive spread in the global livestock industry. Descriptive terms applied to individual animals and herds such as exposed, infected, diseased, clinical, sub-clinical, infectious and resistant need to be defined so that they can be incorporated consistently into well-understood and reproducible case definitions. These allow for consistent classification of individuals in a population for the purposes of analysis based on accurate counts. The outputs might include the incidence of cases, frequency distributions of the number of cases by age class or more sophisticated analyses involving statistical comparisons of immune responses in vaccine development studies, or gene frequencies or expression data from cases and controls in genomic investigations. It is necessary to have agreed definitions in order to be able to make valid comparisons and meta-analyses of experiments conducted over time by a given researcher, in different laboratories, by different researchers, and in different countries. In this paper, terms are applied systematically in an hierarchical flow chart to enable classification of individual animals. We propose descriptive terms for different stages in the pathogenesis of paratuberculosis to enable their use in different types of studies and to enable an independent assessment of the extent to which accepted definitions for stages of disease have been applied consistently in any given study. This will assist in the general interpretation of data between studies, and will facilitate future meta-analyses. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
6. Variation in susceptibility of different breeds of sheep to Mycobacterium avium subspecies paratuberculosis following experimental inoculation.
- Author
-
Begg, D. J., Purdie, A. C., de Silva, K., Dhand, N. K., Plain, K. M., and Whittington, R. J.
- Abstract
Exposure to Mycobacterium avium subspecies paratuberculosis (MAP) does not always lead to Johne's disease. Understanding differences in disease susceptibility of individual animals is a key aspect to controlling mycobacterial diseases. This study was designed to examine the susceptibility or resistance of various breeds of sheep to MAP infection. Merino, Suffolk first cross Merino, Border Leicester, and Poll Dorset sheep were orally inoculated with MAP and monitored for 14 months. Clinical disease occurred more frequently in the Merino (42%) and Suffolk first cross Merino (36%) compared to the Border Leicester (12%) and Poll Dorset (11%) breeds. Infection risk, as determined by culture of gut and associated lymphoid tissues, ranged from 75% for the Suffolk first cross Merino to 47% for the Poll Dorset sheep. Significant differences were identified in the site in the intestines of the most severe histopathological lesions and the immune responses to infection between the breeds. However, there was no difference in faecal MAP shedding by clinical cases between breeds. All breeds tested were susceptible to MAP infection, as determined by infection and clinical disease development, although there were differences in the proportions of diseased animals between the breeds. Poll Dorset and Border Leicester sheep were more resilient to MAP infection but there was evidence that more animals could have developed disease if given more time. These findings provide evidence of potential differential disease susceptibility between breeds, further our understanding of disease pathogenesis and risks of disease spread, and may have an influence on control programs for paratuberculosis. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
7. Types of the cerebral arterial circle (circle of Willis) in a Sri Lankan Population.
- Author
-
De Silva, K. Ranil D., Silva, Rukmal, Amaratunga, Dhammika, Gunasekera, W. S. L., and Jayesekera, Rohan W.
- Subjects
- *
ISCHEMIA , *CEREBROVASCULAR disease , *ARTERIES , *BLOOD circulation disorders - Abstract
Background: The variations of the circle of Willis (CW) are clinically important as patients with effective collateral circulations have a lower risk of transient ischemic attack and stroke than those with ineffective collaterals. The aim of the present cadaveric study was to investigate the anatomical variations of the CW and to compare the frequency of prevalence of the different variations with previous autopsy studies as variations in the anatomy of the CW as a whole have not been studied in the Indian subcontinent. Methods: The external diameter of all the arteries forming the CW in 225 normal Sri Lankan adult cadaver brains was measured using a calibrated grid to determine the prevalence in the variation in CW. Chisquared tests and a correspondence analysis were performed to compare the relative frequencies of prevalence of anatomical variations in the CW across 6 studies of diverse ethnic populations. Results: We report 15 types of variations of CW out of 22 types previously described and one additional type: hypoplastic precommunicating part of the anterior cerebral arteries (A1) and contralateral posterior communicating arteries (PcoA) 5(2%). Statistically significant differences (p < 0.0001) were found between most of the studies except for the Moroccan study. An especially notable difference was observed in the following 4 configurations: 1) hypoplastic precommunicating part of the posterior cerebral arteries (P1), and contralateral A1, 2) hypoplastic PcoA and contralateral P1, 3) hypoplastic PcoA, anterior communicating artery (AcoA) and contralateral P1, 4) bilateral hypoplastic P1s and AcoA in a Caucasian dominant study by Fisher versus the rest of the studies. Conclusion: The present study reveals that there are significant variations in the CW among intra and inter ethnic groups (Caucasian, African and Asian: Iran and Sri Lanka dominant populations), and warrants further studies keeping the methods of measurements, data assessment, and the definitions of hypoplasia the same. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
8. Validation and calibration of a novel GEM biosensor for specific detection of Cd2+, Zn2+, and Pb2+.
- Author
-
Herath, H. M. L. P. B., de Silva, W. R. M., Dassanayake, R. S., Gunawardene, Y. I. N. S., Jayasingha, J. R. P., Gayashan, M. K., Afonso, L. O. B., and de Silva, K. M. N.
- Subjects
- *
BIOSENSORS , *HEAVY metals , *GREEN fluorescent protein , *GENE regulatory networks , *ESCHERICHIA coli , *REPORTER genes , *LOGIC circuits - Abstract
Background: In this study, we designed a novel genetic circuit sensitive to Cd2+, Zn2+ and Pb2+ by mimicking the CadA/CadR operon system mediated heavy metal homeostasis mechanism of Pseudomonas aeruginosa. The regular DNA motifs on natural operon were reconfigured and coupled with the enhanced Green Fluorescent Protein (eGFP) reporter to develop a novel basic NOT type logic gate CadA/CadR-eGFP to respond metal ions mentioned above. A Genetically Engineered Microbial (GEM)-based biosensor (E.coli-BL21:pJET1.2-CadA/CadR-eGFP) was developed by cloning the chemically synthesised CadA/CadR-eGFP gene circuit into pJET1.2-plasmid and transforming into Escherichia coli (E. coli)-BL21 bacterial cells. Results: The GEM-based biosensor cells indicated the reporter gene expression in the presence of Cd2+, Zn2+ and Pb2+ either singly or in combination. Further, the same biosensor cells calibrated for fluorescent intensity against heavy metal concentration generated linear graphs for Cd2+, Zn2+ and Pb2+ with the R2 values of 0.9809, 0.9761 and 0.9758, respectively as compared to non-specific metals, Fe3+ (0.0373), AsO43− (0.3825) and Ni2+ (0.8498) making our biosensor suitable for the detection of low concentration of the former metal ions in the range of 1–6 ppb. Furthermore, the GEM based biosensor cells were growing naturally within the concentration range of heavy metals, at 37 °C and optimum pH = 7.0 in the medium, resembling the characteristics of wildtype E.coli. Conclusion: Finally, the novel GEM based biosensor cells developed in this study can be applied for detection of targeted heavy metals in low concentration ranges (1–6 ppb) at normal bacterial physiological conditions. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
9. Determining dengue infection risk in the Colombo district of Sri Lanka by inferencing the genetic parameters of Aedes mosquitoes.
- Author
-
Chathurangika P, Premadasa LS, Perera SSN, and De Silva K
- Subjects
- Animals, Sri Lanka epidemiology, Humans, Rain, Aedes virology, Aedes genetics, Dengue transmission, Dengue virology, Dengue epidemiology, Mosquito Vectors virology, Mosquito Vectors genetics, Dengue Virus genetics
- Abstract
Background: For decades, dengue has posed a significant threat as a viral infectious disease, affecting numerous human lives globally, particularly in tropical regions, yet no cure has been discovered. The genetic trait of vector competence in Aedes mosquitoes, which facilitates dengue transmission, is difficult to measure and highly sensitive to environmental changes., Methods: In this study we attempt, for the first time in a non-laboratory setting, to quantify the vector competence of Aedes mosquitoes assuming its homogeneity across both species; aegypti and albopictus and across the four Dengue serotypes. Estimating vector competence in relation to varying rainfall patterns was focused in this study to showcase the changes in this vector trait with respect to environmental variables. We quantify it using an existing mathematical model originally developed for malaria in a Bayesian inferencing setup. We conducted this study in the Colombo district of Sri Lanka where the highest number of human populations are threatened with dengue. Colombo district experiences continuous favorable temperature and humidity levels throughout the year creating ideal conditions for Aedes mosquitoes to thrive and transmit the Dengue disease. Therefore we only used the highly variable and seasonal rainfall as the primary environmental variable as it significantly influences the number of breeding sites and thereby impacting the population dynamics of Aedes., Results: Our research successfully deduced vector competence values for the four identified seasons based on Monsoon rainfalls experienced in Colombo within a year. We used dengue data from 2009 - 2022 to infer the estimates. These estimated values have been corroborated through experimental studies documented in the literature, thereby validating the malaria model to estimate vector competence for dengue disease., Conclusion: Our research findings conclude that environmental conditions can amplify vector competence within specific seasons, categorized by their environmental attributes. Additionally, the deduced vector competence offers compelling evidence that it impacts disease transmission, irrespective of geographical location, climate, or environmental factors., (© 2024. The Author(s).)
- Published
- 2024
- Full Text
- View/download PDF
10. Benchmarking for healthy food stores: protocol for a randomised controlled trial with remote Aboriginal and Torres Strait Islander communities in Australia to enhance adoption of health-enabling store policy and practice.
- Author
-
Brimblecombe J, Ferguson M, McMahon E, Fredericks B, Turner N, Pollard C, Maple-Brown L, Batstone J, McCarthy L, Miles E, De Silva K, Barnes A, Chatfield M, Hill A, Christian M, van Burgel E, Fairweather M, Murison A, Lukose D, Gaikwad S, Lewis M, Clancy R, Santos C, Uhlmann K, Funston S, Baddeley L, Tsekouras S, Ananthapavan J, Sacks G, and Lee A
- Subjects
- Humans, Australia, Australian Aboriginal and Torres Strait Islander Peoples, Commerce, Rural Population, Randomized Controlled Trials as Topic, Benchmarking, Diet, Healthy, Food Supply standards
- Abstract
Background: Aboriginal and Torres Strait Islander communities in remote Australia have initiated bold policies for health-enabling stores. Benchmarking, a data-driven and facilitated 'audit and feedback' with action planning process, provides a potential strategy to strengthen and scale health-enabling best-practice adoption by remote community store directors/owners. We aim to co-design a benchmarking model with five partner organisations and test its effectiveness with Aboriginal and Torres Strait Islander community stores in remote Australia., Methods: Study design is a pragmatic randomised controlled trial with consenting eligible stores (located in very remote Northern Territory (NT) of Australia, primary grocery store for an Aboriginal community, and serviced by a Nutrition Practitioner with a study partner organisation). The Benchmarking model is informed by research evidence, purpose-built best-practice audit and feedback tools, and co-designed with partner organisation and community representatives. The intervention comprises two full benchmarking cycles (one per year, 2022/23 and 2023/24) of assessment, feedback, action planning and action implementation. Assessment of stores includes i adoption status of 21 evidence-and industry-informed health-enabling policies for remote stores, ii implementation of health-enabling best-practice using a purpose-built Store Scout App, iii price of a standardised healthy diet using the Aboriginal and Torres Strait Islander Healthy Diets ASAP protocol; and, iv healthiness of food purchasing using sales data indicators. Partner organisations feedback reports and co-design action plans with stores. Control stores receive assessments and continue with usual retail practice. All stores provide weekly electronic sales data to assess the primary outcome, change in free sugars (g) to energy (MJ) from all food and drinks purchased, baseline (July-December 2021) vs July-December 2023., Discussion: We hypothesise that the benchmarking intervention can improve the adoption of health-enabling store policy and practice and reduce sales of unhealthy foods and drinks in remote community stores of Australia. This innovative research with remote Aboriginal and Torres Strait Islander communities can inform effective implementation strategies for healthy food retail more broadly., Trial Registration: ACTRN12622000596707, Protocol version 1., (© 2024. The Author(s).)
- Published
- 2024
- Full Text
- View/download PDF
11. Implementation of a food retail intervention to reduce purchase of unhealthy food and beverages in remote Australia: mixed-method evaluation using the consolidated framework for implementation research.
- Author
-
Brimblecombe J, Miles B, Chappell E, De Silva K, Ferguson M, Mah C, Miles E, Gunther A, Wycherley T, Peeters A, Minaker L, and McMahon E
- Subjects
- Humans, Australia, Marketing, Food Preferences, Food, Beverages
- Abstract
Background: Adoption of health-enabling food retail interventions in food retail will require effective implementation strategies. To inform this, we applied an implementation framework to a novel real-world food retail intervention, the Healthy Stores 2020 strategy, to identify factors salient to intervention implementation from the perspective of the food retailer., Methods: A convergent mixed-method design was used and data were interpreted using the Consolidated Framework for Implementation Research (CFIR). The study was conducted alongside a randomised controlled trial in partnership with the Arnhem Land Progress Aboriginal Corporation (ALPA). Adherence data were collected for the 20 consenting Healthy Stores 2020 study stores (ten intervention /ten control) in 19 communities in remote Northern Australia using photographic material and an adherence checklist. Retailer implementation experience data were collected through interviews with the primary Store Manager for each of the ten intervention stores at baseline, mid- and end-strategy. Deductive thematic analysis of interview data was conducted and informed by the CFIR. Intervention adherence scores derived for each store assisted interview data interpretation., Results: Healthy Stores 2020 strategy was, for the most part, adhered to. Analysis of the 30 interviews revealed that implementation climate of the ALPA organisation, its readiness for implementation including a strong sense of social purpose, and the networks and communication between the Store Managers and other parts of ALPA, were CFIR inner and outer domains most frequently referred to as positive to strategy implementation. Store Managers were a 'make-or-break' touchstone of implementation success. The co-designed intervention and strategy characteristics and its perceived cost-benefit, combined with the inner and outer setting factors, galvanised the individual characteristics of Store Managers (e.g., optimism, adaptability and retail competency) to champion implementation. Where there was less perceived cost-benefit, Store Managers seemed less enthusiastic for the strategy., Conclusions: Factors critical to implementation (a strong sense of social purpose; structures and processes within and external to the food retail organisation and their alignment with intervention characteristics (low complexity, cost advantage); and Store Manager characteristics) can inform the design of implementation strategies for the adoption of this health-enabling food retail initiative in the remote setting. This research can help inform a shift in research focus to identify, develop and test implementation strategies for the wide adoption of health-enabling food retail initiatives into practice., Trial Registration: Australian New Zealand Clinical Trials Registry ACTRN 12,618,001,588,280., (© 2023. The Author(s).)
- Published
- 2023
- Full Text
- View/download PDF
12. Colonization with selected antibiotic resistant bacteria among a cohort of Sri Lankan university students.
- Author
-
Munasinghe T, Vidanapathirana G, Kuthubdeen S, Ekanayake A, Angulmaduwa S, De Silva K, Subhasinghe S, Kalupahana R, Liyanapathirana V, and Ip M
- Subjects
- Adult, Bacteria drug effects, Bacterial Infections drug therapy, Carbapenem-Resistant Enterobacteriaceae isolation & purification, Carbapenems therapeutic use, Cohort Studies, Escherichia coli genetics, Escherichia coli isolation & purification, Escherichia coli Infections microbiology, Female, Humans, Klebsiella isolation & purification, Klebsiella Infections microbiology, Male, Methicillin-Resistant Staphylococcus aureus genetics, Methicillin-Resistant Staphylococcus aureus isolation & purification, Microbial Sensitivity Tests, Sri Lanka, Staphylococcal Infections microbiology, Students, Young Adult, beta-Lactamases genetics, Anti-Bacterial Agents therapeutic use, Bacterial Infections epidemiology, Bacterial Infections microbiology, Drug Resistance, Bacterial, Universities
- Abstract
Background: Antibiotic Resistance is an imminent global public health threat. Antibiotic resistance emerged in healthcare settings and has now moved on to the community settings. This study was conducted to identify the rates of asymptomatic colonization with selected antibiotic resistant organisms, (Methicillin Resistant Staphylococcus aureus (MRSA), Extended Spectrum Beta Lactamase (ESBL) producing Escherichia coli and Klebsiella spp and carbapenem resistant E.coli and Klebsiella spp) - among a group of university students in Sri Lanka. Identification of genetic determinants of MRSA and ESBL was an additional objective of the study., Methods: A self - collected nasal swab and a peri-rectal swab collected after passing stools were obtained. Routine microbiological methods were used for the isolation S.aureus from the nasal swab and E.coli and Klebsiella species from the peri-rectal swab. Antibiotic sensitivity testing was performed as recommended by clinical and laboratory standard institute (CLSI). Three (3) genes that are responsible for ESBL production; bla
CTX-M , blaSHV , and blaTEM were tested using previously described primers and PCR procedures. Identification of MecA and PVL genes attributed to MRSA was also done with PCR., Results: A total of 322 participants between 21 and 28 years were recruited representing 5 different faculties of study. Seventy one (22.0%) were colonized with S.aureus and 14 among them with MRSA, making the MRSA colonization rate of 4.3%. Forty five (15%) of the participants were colonized with an ESBL producing E.coli or Klebsiella spp. No one was colonized with carbapenem resistant E.coli or Klebsiella species. Of the 45 ESBL producers the commonest genetic determinant identified was blaCTX-M (n = 36), while 16 isolates had blaTEM and 7 had blaSHV. Similarly, of the 14 isolates identified as MRSA, 3 (21.4%) were found to be PVL positive while 11 (78.6%) were MecA positive., Conclusions: A high rate of colonization with ESBL producing E.coli and Klebsiella species was noted in our study group.- Published
- 2021
- Full Text
- View/download PDF
13. Pattern of nucleotide variants of TP53 and their correlation with the expression of p53 and its downstream proteins in a Sri Lankan cohort of breast and colorectal cancer patients.
- Author
-
Manoharan V, Karunanayake EH, Tennekoon KH, De Silva S, Imthikab AIA, De Silva K, Angunawela P, Vishwakula S, and Lunec J
- Subjects
- Adult, Aged, Alleles, Amino Acid Sequence, Biomarkers, Tumor, Case-Control Studies, Databases, Factual, Female, Gene Expression, Genotype, Humans, Immunohistochemistry, Male, Middle Aged, Public Health Surveillance, Sri Lanka epidemiology, Structure-Activity Relationship, Tumor Suppressor Protein p53 chemistry, Breast Neoplasms epidemiology, Breast Neoplasms genetics, Colorectal Neoplasms epidemiology, Colorectal Neoplasms genetics, Gene Expression Regulation, Neoplastic, Genetic Variation, Tumor Suppressor Protein p53 genetics
- Abstract
Background: Breast cancer (BC) is known to be the most common malignancy in females whereas colorectal cancer (CRC) incidence also higher in both genders in Sri Lanka. TP53 is an important tumour suppressor gene and its somatic mutations are reported in approximately 27% of BC and 43% of CRC cases. Analysis of TP53 gene variants not only provides clues for the aetiology of the tumour formation, but also has an impact on treatment efficacy. The current study was conducted to investigate the pattern of TP53 variants in patients with BC and CRC from Sri Lanka., Methods: 30 patients with BC, 21 patients with CRC and an equal number of healthy controls were screened for mutational status of TP53 by polymerase chain reaction (PCR) followed by direct sequencing. In addition, a subset of these samples were analysed for the protein expression of p53 and comparison made with the mutational status of TP53. We also analysed the protein expression of p21 and MDM2 as potential indicators of p53 functional status and compared it with the protein expression of p53. Additionally, hotspot codons of the KRAS, BRAF and PIK3CA genes were also analysed in a subset of CRC patients., Results: Twenty seven sequence variants, including several novel variants in the TP53 gene were found. Nine BC and seven CRC tumour samples carried pathogenic TP53 variants. Pathogenic point missense variants were associated with strong and diffuse positive staining for p53 by immunohistochemistry (IHC), whereas, wild type TP53 showed complete absence of positive IHC staining or rare positive cells, regardless of the type of cancer. There was no direct correlation between p21 or MDM2 expression and p53 expression in either BCs or CRCs. Four of the CRC patients had pathogenic hotspot variants in KRAS; three of them were on codon 12 and one was on codon 61., Conclusion: The prevalence of pathogenic somatic TP53 variants was 31 and 33.33% in the studied BC and CRC cohorts respectively. All of them were located in exons 5-8 and the pathogenic missense variants were associated with strong immuno-positive staining for p53.
- Published
- 2020
- Full Text
- View/download PDF
14. The humoral immune response is essential for successful vaccine protection against paratuberculosis in sheep.
- Author
-
Pooley HB, Begg DJ, Plain KM, Whittington RJ, Purdie AC, and de Silva K
- Subjects
- Animals, Antibodies, Bacterial blood, Bacterial Vaccines administration & dosage, Immunity, Humoral, Immunoglobulin G blood, Male, Mycobacterium avium subsp. paratuberculosis immunology, Paratuberculosis prevention & control, Sheep, Sheep Diseases microbiology, Sheep, Domestic, Vaccination veterinary, Bacterial Vaccines immunology, Paratuberculosis immunology, Sheep Diseases immunology
- Abstract
Background: The role played by the humoral immune response in animals vaccinated against a mycobacterial disease such as paratuberculosis, is not well understood. Sheep vaccinated against Mycobacterium avium subsp. paratuberculosis (MAP) can still become infected and in some cases succumb to clinical disease. The strength and location of the humoral immune response following vaccination could contribute to the ability of sheep to clear MAP infection. We examined the peripheral antibody response along with the localised humoral response at the site of paratuberculosis infection, the ileum, to better understand how this contributes to MAP infection of sheep following vaccination and exposure., Results: Through assessing MAP specific serum IgG1 and IgG levels we show that the timing and strength of the humoral immune response directly relates to prevention of infection following vaccination. Vaccinated sheep that subsequently became infected had significantly reduced levels of MAP specific serum IgG1 early after vaccination. In contrast, vaccinated sheep that did not subsequently become infected had significantly elevated MAP specific serum IgG1 following vaccination. Furthermore, at 12 months post MAP exposure, vaccinated and subsequently uninfected sheep had downregulated expression of genes related to the humoral response in contrast to vaccinated infected sheep where expression levels were upregulated., Conclusions: The timing and strength of the humoral immune response following vaccination against paratuberculosis in sheep directly relates to subsequent infection status. An initial strong IgG1 response following vaccination was crucial to prevent infection. Additionally, vaccinated uninfected sheep were able to modulate that response following apparent MAP clearance, unlike vaccinated infected animals where there was apparent dysregulation of the humoral response, which is associated with progression to clinical disease.
- Published
- 2019
- Full Text
- View/download PDF
15. Fabrication of 6-gingerol, doxorubicin and alginate hydroxyapatite into a bio-compatible formulation: enhanced anti-proliferative effect on breast and liver cancer cells.
- Author
-
Manatunga DC, de Silva RM, de Silva KMN, Wijeratne DT, Malavige GN, and Williams G
- Abstract
Ample attention has been devoted to the construction of anti-cancer drug delivery systems with increased stability, and controlled and targeted delivery, minimizing toxic effects. In this study we have designed a magnetically attractive hydroxyapatite (m-HAP) based alginate polymer bound nanocarrier to perform targeted, controlled and pH sensitive drug release of 6-gingerol, doxorubicin, and their combination, preferably at low pH environments (pH 5.3). They have exhibited higher encapsulation efficiency which is in the range of 97.4-98.9% for both 6-gingerol and doxorubicin molecules whereas the co-loading has accounted for a value of 81.87 ± 0.32%. Cell proliferation assays, fluorescence imaging and flow cytometric analysis, demonstrated the remarkable time and dose responsive anti-proliferative effect of drug loaded nanoparticles on MCF-7 cells and HEpG2 cells compared with their neat counter parts. Also, these systems have exhibited significantly reduced toxic effects on non-targeted, non-cancerous cells in contrast to the excellent ability to selectively kill cancerous cells. This study has suggested that this HAP based system is a versatile carrier capable of loading various drug molecules, ultimately producing a profound anti-proliferative effect.
- Published
- 2018
- Full Text
- View/download PDF
16. Synthesis of multifunctional activated carbon nanocomposite comprising biocompatible flake nano hydroxyapatite and natural turmeric extract for the removal of bacteria and lead ions from aqueous solution.
- Author
-
Jayaweera HDAC, Siriwardane I, de Silva KMN, and de Silva RM
- Abstract
Clean water, which is free from pathogens and toxic chemicals, is vital to human health. The blue planet is encountering remarkable challenges in meeting the ever-increasing demands of clean water. The intention of this research study was to develop a water filter material that is capable of removing bacterial contaminants and heavy metals from fresh water using cost effective and easily fabricated biocompatible filter material. For this purpose, granular activated carbon (GAC) was coated with both hydroxyapatite (HAP) nanoflakes and turmeric extract (TE) (HAP/TE/GAC) which had been extracted from natural turmeric powder. In addition, GAC was coated only with HAP nanoflakes to synthesize HAP coated GAC (HAP/GAC) composite. Prepared HAP/GAC and HAP/TE/GAC were characterized using Fourier-transform infrared spectroscopy, X-ray diffractometry, scanning electron microscopy and UV-visible spectrophotometry. Antibacterial effect of the prepared nanocomposites, HAP/GAC and HAP/TE/GAC was compared with neat GAC using Gram-negative bacteria Escherichia coli. Results showed that antibacterial studies of the synthesized nanocomposites exhibit effective antibacterial activity against E. coli compared with neat GAC alone. However, the composite HAP/TE/GAC revealed better activity than HAP/GAC. Heavy metal adsorption ability of the synthesized composites was carried out using Pb
2+ ions at room temperature at different time intervals and different pH levels. The equilibrium adsorption data were assessed via Langmuir and Freundlich adsorption isotherm models for neat GAC, HAP/GAC and HAP/TE/GAC at pH 6. The equilibrium adsorption data for GAC, HAP/GAC and HAP/TE/GAC were well fitted with both Freundlich and Langmuir isotherm models in the given Pb2+ concentrations. The HAP/TE/GAC composite is capable of maintaining the natural function of GAC in addition to removal of bacterial contaminants and heavy metals, which can be used as a point-of-use water filter material.- Published
- 2018
- Full Text
- View/download PDF
17. Evaluation of the limitations and methods to improve rapid phage-based detection of viable Mycobacterium avium subsp. paratuberculosis in the blood of experimentally infected cattle.
- Author
-
Swift BM, Huxley JN, Plain KM, Begg DJ, de Silva K, Purdie AC, Whittington RJ, and Rees CE
- Subjects
- Animals, Bacteriophages, Cattle, Cattle Diseases blood, Enzyme-Linked Immunosorbent Assay veterinary, Magnetics, Male, Paratuberculosis blood, Bacteriological Techniques methods, Bacteriological Techniques veterinary, Cattle Diseases microbiology, Mycobacterium avium subsp. paratuberculosis isolation & purification, Paratuberculosis microbiology
- Abstract
Background: Disseminated infection and bacteraemia is an underreported and under-researched aspect of Johne's disease. This is mainly due to the time it takes for Mycobacterium avium subsp. paratuberculosis (MAP) to grow and lack of sensitivity of culture. Viable MAP cells can be detected in the blood of cattle suffering from Johne's disease within 48 h using peptide-mediated magnetic separation (PMMS) followed by bacteriophage amplification. The aim of this study was to demonstrate the first detection of MAP in the blood of experimentally exposed cattle using the PMMS-bacteriophage assay and to compare these results with the immune response of the animal based on serum ELISA and shedding of MAP by faecal culture., Results: Using the PMMS-phage assay, seven out of the 19 (37 %) MAP-exposed animals that were tested were positive for viable MAP cells although very low numbers of MAP were detected. Two of these animals were positive by faecal culture and one was positive by serum ELISA. There was no correlation between PMMS-phage assay results and the faecal and serum ELISA results. None of the control animals (10) were positive for MAP using any of the four detection methods. Investigations carried out into the efficiency of the assay; found that the PMMS step was the limiting factor reducing the sensitivity of the phage assay. A modified method using the phage assay directly on isolated peripheral blood mononuclear cells (without PMMS) was found to be superior to the PMMS isolation step., Conclusions: This proof of concept study has shown that viable MAP cells are present in the blood of MAP-exposed cattle prior to the onset of clinical signs. Although only one time point was tested, the ability to detect viable MAP in the blood of subclinically infected animals by the rapid phage-based method has the potential to increase the understanding of the pathogenesis of Johne's disease progression by warranting further research on the presence of MAP in blood.
- Published
- 2016
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.