MyMedR

Displaying all 7 publications

Abstract:

Sort:

Polyunsaturated fatty acid levels in red cell membranes of unmedicated schizophrenic patients

Peet M, Shah S, Selvam K, Ramchand CN

World J Biol Psychiatry, 2004 Apr;5(2):92-9.
PMID: 15179668

There are several reports of reduced levels of polyunsaturated fatty acids (PUFA), particularly arachidonic acid (AA) and docosahexaenoic acid (DHA), in membrane phospholipid from various tissues including red blood cells (RBC) taken from schizophrenic patients. However, reports have not been entirely consistent and most studies have been confounded by the potential effects of environmental factors including antipsychotic medication and diet. We measured PUFA levels in RBC from two separate groups of unmedicated patients and control subjects from India and Malaysia, populations which have substantial differences in diet. We found no significant difference in levels of AA between patients and control subjects in either population. Levels of adrenic acid were significantly reduced, and levels of DHA significantly increased in both clinical populations. However, diet-related differences in DHA between the populations from India and Malaysia were much greater than differences between schizophrenic patients and controls. It is concluded that reduced RBC membrane levels of AA and DHA are not pathognomic of schizophrenia but that variations in cell membrane fatty acid levels are an epiphenomenon which may reflect underlying abnormalities of phospholipid and fatty acid metabolism and their interaction with environmental factors including medication and diet.
Fulltext BipD of Burkholderia pseudomallei: Structure, Functions, and Detection Methods

Selvam K, Khalid MF, Mustaffa KMF, Harun A, Aziah I

Microorganisms, 2021 Mar 30;9(4).
PMID: 33808203 DOI: 10.3390/microorganisms9040711

Melioidosis is a severe disease caused by Burkholderia pseudomallei (B. pseudomallei), a Gram-negative environmental bacterium. It is endemic in Southeast Asia and Northern Australia, but it is underreported in many other countries. The principal routes of entry for B. pseudomallei are skin penetration, inhalation, and ingestion. It mainly affects immunocompromised populations, especially patients with type 2 diabetes mellitus. The laboratory diagnosis of melioidosis is challenging due to its non-specific clinical manifestations, which mimic other severe infections. The culture method is considered an imperfect gold standard for the diagnosis of melioidosis due to its low sensitivity. Antibody detection has low sensitivity and specificity due to the high seropositivity among healthy people in endemic regions. Antigen detection using various proteins has been tested for the rapid determination of B. pseudomallei; however, it presents certain limitations in terms of its sensitivity and specificity. Therefore, this review aims to frame the present knowledge of a potential target known as the Burkholderia invasion protein D (BipD), including future directions for its detection using an aptamer-based sensor (aptasensor).
Fulltext RT-LAMP CRISPR-Cas12/13-Based SARS-CoV-2 Detection Methods

Selvam K, Najib MA, Khalid MF, Mohamad S, Palaz F, Ozsoz M, et al.

Diagnostics (Basel), 2021 Sep 08;11(9).
PMID: 34573987 DOI: 10.3390/diagnostics11091646

Coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), has attracted public attention. The gold standard for diagnosing COVID-19 is reverse transcription-quantitative polymerase chain reaction (RT-qPCR). However, RT-qPCR can only be performed in centralized laboratories due to the requirement for advanced laboratory equipment and qualified workers. In the last decade, clustered regularly interspaced short palindromic repeats (CRISPR) technology has shown considerable promise in the development of rapid, highly sensitive, and specific molecular diagnostic methods that do not require complicated instrumentation. During the current COVID-19 pandemic, there has been growing interest in using CRISPR-based diagnostic techniques to develop rapid and accurate assays for detecting SARS-CoV-2. In this work, we review and summarize reverse-transcription loop-mediated isothermal amplification (RT-LAMP) CRISPR-based diagnostic techniques for detecting SARS-CoV-2.
Fulltext Burden and Risk Factors of Melioidosis in Southeast Asia: A Scoping Review

Selvam K, Ganapathy T, Najib MA, Khalid MF, Abdullah NA, Harun A, et al.

Int J Environ Res Public Health, 2022 Nov 22;19(23).
PMID: 36497549 DOI: 10.3390/ijerph192315475

This scoping review aims to provide a comprehensive overview of human melioidosis in Southeast Asia as well as to highlight knowledge gaps in the prevalence and risk factors of this life-threatening disease using available evidence-based data for better diagnosis and treatment. Preferred Reporting Items for Systematic Review and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR) was used as the guideline for this review. The literature search was conducted on 23 March 2022 through two electronic databases (PubMed and Scopus) using lists of keywords referring to the Medical Subject Headings (MeSH) thesaurus. A total of 38 articles related to human melioidosis were included from 645 screened articles. These studies were carried out between 1986 and 2019 in six Southeast Asian countries: Thailand, Cambodia, Malaysia, Myanmar, Singapore, and Vietnam. Melioidosis has been reported with a high disease prevalence among high-risk populations. Studies in Thailand (48.0%) and Cambodia (74.4%) revealed disease prevalence in patients with septic arthritis and children with suppurative parotitis, respectively. Other studies in Thailand (63.5%) and Malaysia (54.4% and 65.7%) showed a high seroprevalence of melioidosis among Tsunami survivors and military personnel, respectively. Additionally, this review documented soil and water exposure, diabetes mellitus, chronic renal failure, thalassemia, and children under the age of 15 as the main risk factors for melioidosis. Human melioidosis is currently under-reported in Southeast Asia and its true prevalence is unknown.
Isolation and characterization of ssDNA aptamers against BipD antigen of Burkholderia pseudomallei

Selvam K, Najib MA, Khalid MF, Yunus MH, Wahab HA, Harun A, et al.

Anal Biochem, 2024 Aug 28;695:115655.
PMID: 39214325 DOI: 10.1016/j.ab.2024.115655

BACKGROUND: Melioidosis is difficult to diagnose due to its wide range of clinical symptoms. The culture method is time-consuming and less sensitive, emphasizing the importance of rapid and accurate diagnostic tests for melioidosis. Burkholderia invasion protein D (BipD) of Burkholderia pseudomallei is a potential diagnostic biomarker. This study aimed to isolate and characterize single-stranded DNA aptamers that specifically target BipD.
METHODS: The recombinant BipD protein was produced, followed by isolation of BipD-specific aptamers using Systematic Evolution of Ligands by EXponential enrichment. The binding affinity and specificity of the selected aptamers were evaluated using Enzyme-Linked Oligonucleotide Assay.
RESULTS: The fifth SELEX cycle showed a notable enrichment of recombinant BipD protein-specific aptamers. Sequencing analysis identified two clusters with a total of seventeen distinct aptamers. AptBipD1, AptBipD13, and AptBipD50 were chosen based on their frequency. Among them, AptBipD1 exhibited the highest binding affinity with a Kd value of 1.0 μM for the recombinant BipD protein. Furthermore, AptBipD1 showed significant specificity for B. pseudomallei compared to other tested bacteria.
CONCLUSION: AptBipD1 is a promising candidate for further development of reliable, affordable, and efficient point-of-care diagnostic tests for melioidosis.
Fulltext Performance of Immunodiagnostic Tests for Typhoid Fever: A Systematic Review and Meta-Analysis

Najib MA, Mustaffa KMF, Ong EBB, Selvam K, Khalid MF, Awang MS, et al.

Pathogens, 2021 Sep 13;10(9).
PMID: 34578216 DOI: 10.3390/pathogens10091184

Typhoid fever, also known as typhoid, is a life-threatening bacterial infection that remains a global health concern. The infection is associated with a significant morbidity and mortality rate, resulting in an urgent need for specific and rapid detection tests to aid prevention and management of the disease. The present review aims to assess the specificity and sensitivity of the available literature on the immunodiagnostics of typhoid fever. A literature search was conducted using three databases (PubMed, ProQuest and Scopus) and manual searches through the references of identified full texts to retrieve relevant literature published between 1 January 2011 and 31 December 2020. Of the 577 studies identified in our search, 12 were included in further analysis. Lipopolysaccharides (LPS) and hemolysin E (HlyE) were the most frequently studied antigens. The specimens examined in these studies included serum and saliva. Using blood culture as the gold standard, anti-LPS IgA gave the highest sensitivity of 96% (95% CI: 93-99) and specificity of 96% (95% CI: 93-99) for distinguishing between typhoid cases and healthy controls, whereas the combination of anti-LPS and anti-flagellin total IgGAM gave the highest sensitivity of 93% (95% CI: 86-99) and specificity of 95% (95% CI: 89-100) for distinguishing typhoid cases and other febrile infections. A comparably high sensitivity of 92% (95% CI: 86-98) and specificity of 89% (95% CI: 78-100) were shown in testing based on detection of the combination of anti-LPS (IgA and IgM) and anti-HlyE IgG as well as a slightly lower sensitivity of 91% (95% CI: 74-100) in the case of anti-50kDa IgA. Anti-50kDa IgM had the lowest sensitivity of 36% (95% CI: 6-65) against both healthy and febrile controls. The development of a rapid diagnostic test targeting antibodies against lipopolysaccharides combined with flagellin appeared to be a suitable approach for the rapid detection test of typhoid fever. Saliva is added benefit for rapid typhoid diagnosis since it is less invasive. As a result, further studies could be done to develop additional approaches for adopting such samples.
Fulltext Isolation and characterization of DNA aptamers against the HlyE antigen of Salmonella Typhi

Ahmad Najib M, Winter A, Mustaffa KMF, Ong EBB, Selvam K, Khalid MF, et al.

Sci Rep, 2024 Nov 18;14(1):28416.
PMID: 39557915 DOI: 10.1038/s41598-024-78685-9

Aptamers have emerged as prominent ligands in clinical diagnostics because they provide various advantages over antibodies, such as quicker generation time, reduced manufacturing costs, minimal batch-to-batch variability, greater modifiability, and improved thermal stability. In the present study, we isolated and characterized DNA aptamers that can specifically bind to the hemolysin E (HlyE) antigen of Salmonella Typhi for future development of typhoid diagnostic tests. The DNA aptamers against Salmonella Typhi HlyE were isolated using systematic evolution of ligands by exponential enrichment (SELEX), and their binding affinity and specificity were assessed utilizing enzyme-linked oligonucleotide assay (ELONA). A total of 11 distinct aptamers were identified, and the binding affinities and species selectivities of the three most probable aptamers were determined. Kd values were obtained in the nanomolar range, with the highest affinity of 83.6 nM determined for AptHlyE97. In addition, AptHlyE11, AptHlyE45 and AptHlyE97 clearly distinguished S. Typhi HlyE from other tested bacteria, such as Salmonella Paratyphi A, Salmonella Paratyphi B, Shigella flexneri, Klebsiella pneumonia and Escherichia coli, therefore displaying desirable specificity. These novel aptamers could be used as diagnostic ligands for the future development of inexpensive and effective point-of-care tests for typhoid surveillance, especially in developing countries of the tropics and subtropics.