Displaying publications 61 - 68 of 68 in total

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  1. Magalingam KB, Somanath SD, Radhakrishnan AK
    Exp Neurobiol, 2023 Jun 30;32(3):119-132.
    PMID: 37403221 DOI: 10.5607/en22035
    A cell-based model of Parkinson's disease (PD) is a well-established in vitro experimental prototype to investigate the disease mechanism and therapeutic approach for a potential anti-PD drug. The SH-SY5Y human neuroblastoma cells and 6-OHDA combo is one of the many neurotoxininduced neuronal cell models employed in numerous neuroscience-related research for discovering neuroprotective drug compounds. Emerging studies have reported a significant correlation between PD and epigenetic alterations, particularly DNA methylation. However, the DNA methylation changes of PD-related CpG sites on the 6-OHDA-induced toxicity on human neuronal cells have not yet been reported. We performed a genome-wide association study (GWAS) using Infinium Epic beadchip array surveying 850000 CpG sites in differentiated human neuroblastoma cells exposed to 6-OHDA. We identified 236 differentially methylated probes (DMPs) or 163 differentially methylated regions (DMRs) in 6-OHDA treated differentiated neuroblastoma cells than the untreated reference group with p<0.01, Δbeta cut-off of 0.1. Among 236 DMPs, hypermethylated DMPs are 110 (47%), whereas 126 (53%) are hypomethylated. Our bioinformatic analysis revealed 3 DMRs that are significantly hypermethylated and associated with neurological disorders, namely AKT1, ITPR1 and GNG7. This preliminary study demonstrates the methylation status of PD-related CpGs in the 6-OHDA-induced toxicity in the differentiated neuroblastoma cells model.
  2. Md S, Abdullah ST, Alhakamy NA, Bani-Jaber A, Radhakrishnan AK, Karim S, et al.
    Gels, 2021 Nov 30;7(4).
    PMID: 34940303 DOI: 10.3390/gels7040243
    This study aimed to develop gastro-retentive sustained-release ambroxol (ABX) nanosuspensions utilizing ambroxol-kappa-carrageenan (ABX-CRGK) complexation formulations. The complex was characterized by differential scanning calorimetry, powder x-ray diffractometer, and scanning electron microscopy. The prepared co-precipitate complex was used for the development of the sustained-release formulation to overcome the high metabolic and poor solubility problems associated with ABX. Furthermore, the co-precipitate complex was formulated as a suspension in an aqueous floating gel-forming vehicle of sodium alginate with chitosan, which might be beneficial for targeting the stomach as a good absorption site for ABX. The suspension exhibited rapid floating gel behaviour for more than 8 h, thus confirming the gastro-retentive effects. Particle size analysis revealed that the optimum nanosuspension (ABX-NS) had a mean particle size of 332.3 nm. Afterward, the ABX released by the nanoparticles would be distributed to the pulmonary tissue as previously described. Based on extensive pulmonary distribution, the developed nanosuspension-released ABX nanoparticles showed significant cytotoxic enhancement compared to free ABX in A549 lung cancer cells. However, a significant loss of mitochondrial membrane potential (MMP) also occurred. The level of caspase-3 was the highest in the ABX-NS-released particle-treated samples, with a value of 416.6 ± 9.11 pg/mL. Meanwhile, the levels of nuclear factor kappa beta, interleukins 6 and 1 beta, and tumour necrosis alpha (NF-kB, IL-6, IL-1β, and TNF-α, respectively) were lower for ABX-NS compared to free ABX (p < 0.05). In caspase-3, Bax, and p53, levels significantly increased in the presence of ABX-NS compared to free ABX. Overall, ABX-NS produced an enhancement of the anticancer effects of ABX on the A549 cells, and the developed sustained-release gel was successful in providing a gastro-retentive effect.
  3. Munisamy S, Radhakrishnan AK, Ramdas P, Samuel PJ, Singh VA
    Curr Oncol, 2022 Aug 05;29(8):5585-5603.
    PMID: 36005179 DOI: 10.3390/curroncol29080441
    The main role of the host immune system is to identify and eliminate cancer cells, which is a complex process, but it is not a fail-safe mechanism. Many sarcoma patients succumb to this disease despite treatments rendered. The aim of this pilot study was to compare the levels of CD4+ T-cells, T-regulatory (Treg) cells, and cytokines such as tumor necrosis factor-alpha (TNF-α), interferon-gamma (IFN-γ), interleukin-17A (IL-17A), and transforming growth factor-beta-1 (TGF-β1) in peripheral blood leukocytes of sarcoma patients and healthy controls. For gene expression studies, total ribonucleic acid (RNA) was extracted from peripheral blood leukocytes and genes that were differentially regulated in peripheral blood leukocytes of sarcoma patients compared with healthy controls were determined using a commercial T-helper cell differentiation quantitative polymerase chain reaction (qPCR) array. Flow cytometer analysis was performed on blood samples from 26 sarcoma patients and 10 healthy controls to identify the levels of CD4+ T-cells and T-reg cells. The level of cytokines in plasma and culture supernatant were quantified using commercial enzyme-linked immunosorbent assay (ELISA) kits. A marked reduction in the percentage of CD4+ T-cells (p = 0.037) and levels of TNF-α (p = 0.004) and IFN-γ (0.010) was observed in sarcoma patients. Gene expression analysis showed five genes (homeobox A10 (HOXA10), GATA binding protein 3 (GATA3), prostaglandin D2 receptor 2 (PTGDR2), thymocyte selection associated high mobility group box (TOX), and C-C motif chemokine receptor 3 (CCR3)) were dysregulated (p < 0.05) in sarcoma patients. This study suggests that T-helper-1 immune responses are reduced in sarcoma patients.
  4. Kanathasan JS, Palanisamy UD, Radhakrishnan AK, Chakravarthi S, Thong TB, Swamy V
    Nanomedicine (Lond), 2022 Sep;17(21):1511-1528.
    PMID: 36382634 DOI: 10.2217/nnm-2022-0017
    Background: Porous silicon (pSi) nanoparticles (NPs) functionalized with suitable targeting ligands are now established cancer bioimaging agents and drug-delivery platforms. With growing interest in peptides as tumor-targeting ligands, much work has focused on the use of various peptides in combination with pSi NPs for cancer theranostics. Here, the authors investigated the targeting potential of pSi NPs functionalized with two types of peptide, a linear 10-mer peptide and its branched (Y-shaped) equivalent, that respond to legumain activity in tumor cells. Results: In vitro experiments established that the linear peptide-pSi NP conjugate had better aqueous stability under tumor conditions and higher binding efficiency (p  0.05) of linear peptide-conjugated pSi NPs in the tumor site within 4 h compared with nonconjugated pSi NPs. These results suggest that the linear peptide-pSi NP formulation is a nontoxic, stable and efficient fluorescence bioimaging agent and potential drug-delivery platform.
  5. Loganathan R, Subramaniam KM, Radhakrishnan AK, Choo YM, Teng KT
    Nutr Rev, 2017 Feb 01;75(2):98-113.
    PMID: 28158744 DOI: 10.1093/nutrit/nuw054
    The fruit of the oil palm tree (Elaeis guineesis) is the source of antioxidant-rich red palm oil. Red palm oil is a rich source of phytonutrients such as tocotrienols, tocopherols, carotenoids, phytosterols, squalene, and coenzyme Q10, all of which exhibit nutritional properties and oxidative stability. Mutagenic, nutritional, and toxicological studies have shown that red palm oil contains highly bioavailable β-carotene and vitamin A and is reasonably stable to heat without any adverse effects. This review provides a comprehensive overview of the nutritional properties of red palm oil. The possible antiatherogenic, antihemorrhagic, antihypertensive, anticancer, and anti-infective properties of red palm oil are examined. Moreover, evidence supporting the potential effectiveness of red palm oil to overcome vitamin A deficiency in children and pregnant women, to improve ocular complications of vitamin A deficiency, to protect against ischemic heart disease, to promote normal reproduction in males and females, to aid in the management of diabetes, to ameliorate the adverse effects of chemotherapy, and to aid in managing hypobaric conditions is presented.
  6. Thambiah SC, Wong TH, Das Gupta E, Radhakrishnan AK, Gun SC, Chembalingam G, et al.
    Malays J Pathol, 2018 Dec;40(3):287-294.
    PMID: 30580359
    INTRODUCTION: Low 25-hydroxyvitamin D [25(OH)D] levels have not been consistently associated with bone mineral density (BMD). It has been suggested that calculation of the free/bioavailable 25(OH)D may correlate better with BMD. We examined this hypothesis in a cohort of Malaysian women.

    MATERIALS AND METHODS: A cross-sectional study of 77 patients with rheumatoid arthritis (RA) and 29 controls was performed. Serum 25(OH)D was measured using the Roche Cobas E170 immunoassay. Serum vitamin D binding protein (VDBP) was measured using a monoclonal enzyme-linked immunosorbent assay (ELISA). Free/bioavailable 25(OH)D were calculated using both the modified Vermuelen and Bikle formulae.

    RESULTS: Since there were no significant differences between RA patients and controls for VDBP and 25(OH)D, the dataset was analysed as a whole. Calculated free 25(OH)D by Vermeulen was strongly correlated with Bikle (r = 1.00, p < 0.001). A significant positive correlation was noted between measured total 25(OH)D with free/bioavailable 25(OH)D (r = 0.607, r = 0.637, respectively, p < 0.001). Median free/bioavailable 25(OH)D values were significantly higher in Chinese compared with Malays and Indians, consistent with their median total 25(OH)D. Similar to total 25(OH)D, the free/bioavailable 25(OH)D did not correlate with BMD.

    CONCLUSION: In this first study of a multiethnic female Malaysian population, free/bioavailable 25(OH)D were found to reflect total 25(OH)D, and was not superior to total 25(OH)D in its correlation with BMD. Should they need to be calculated, the Bikle formula is easier to use but only calculates free 25(OH)D. The Vermuelen formula calculates both free/bioavailable 25(OH)D but is more complex to use.
  7. Wong TH, Das Gupta E, Radhakrishnan AK, Gun SC, Chembalingam G, Yeap SS
    MyJurnal
    Rheumatoid arthritis (RA) is a chronic inflammatory condition that can be associated with abnormal bone turnover and hence osteoporosis. Osteocalcin (OC) levels are increased in conditions with high bone turnover, including high RA disease activity. Thus, OC levels could possibly be used as a marker to assess bone health and disease activity in RA patients. As there have been no previous studies looking at serum OC levels in Malaysian RA patients, this study was performed to examine possible correlations between OC, bone mineral density (BMD) and disease activity in this population. A cross-sectional study of 75 female RA patients and 29 healthy controls was performed. Serum OC was measured using a Quantikine® ELISA kit. Dualenergy x-ray absorptiometry (DXA) was used to assess BMD. Serum OC levels were not significantly different between RA patients (median 14.44 ng/mL, interquartile range [IQR 12.99]) compared to healthy controls (median 11.04 ng/mL IQR 12.29) (p=0.198). Serum OC increased with age (Spearman’s rho r=0.230, p=0.047). There was no significant correlation between serum OC and body mass index (BMI), menopause status, BMD, DAS28, swollen or tender joint counts. Overall, there were 11 (14.7%) patients with osteoporosis and 27 (36.0%) with osteopenia. Menopause status was significantly associated with BMD at all sites (lumbar spine p=0.002, femoral neck p=0.004, total hip p=0.002). Serum OC were similar in RA patients compared to healthy controls. In RA patients, serum OC did not correlate with RA disease activity or BMD. Menopause status remains an important influence on BMD. Thus, measuring serum OC levels in Malaysian RA patients was not useful in identifying those at risk of low BMD.
    Study site: Rheumatology clinic, Hospital Tuanku Jaafar, Seremban, Negeri Sembilan, and Klinik Pakar Puchong, Kuala Lumpur, Malaysia
  8. Wong TH, Das Gupta E, Radhakrishnan AK, Gun SC, Chembalingam G, Yeap SS
    Int J Rheum Dis, 2018 May;21(5):992-1000.
    PMID: 28217867 DOI: 10.1111/1756-185X.13048
    AIM: Vitamin D3 [25(OH)D] has been shown to be important in bone health and can influence rheumatoid arthritis (RA) disease activity. Vitamin D-binding protein (VDBP) levels vary with race and may modulate 'bioavailable' levels of 25(OH)D. The aim of this study was to explore the relationships between 25(OH)D, VDBP and clinical factors on bone mineral density (BMD) in a group of multi-ethnic Malaysian RA patients and healthy controls.

    METHODS: A cross-sectional study of 77 female RA patients and 29 controls was performed. Serum 25(OH)D was measured using the Elecsys® Vitamin D total assay. Serum VDBP was measured using a Quantikine® enzyme-linked immunosorbent assay kit. BMD was assessed using dual-energy X-ray absorptiometry (DXA).

    RESULTS: Overall, mean 25(OH)D levels were 42.66 ± 21.75 nmol/L with no significant difference between RA patients and controls. 25(OH)D levels were significantly higher in Chinese, compared to Malay/Indian subjects. In RA patients, menopausal status and body mass index (BMI) were significantly associated with BMD but not 25(OH)D or RA Disease Activity Score of 28 joints (DAS28). There was no significant correlation between 25(OH)D and DAS28, even after correction for menopausal status and BMI. VDBP levels were not significantly different between the races and did not significantly correlate with BMD, 25(OH)D overall, or DAS28 in RA patients.

    CONCLUSIONS: In Malaysian RA patients, menopausal status and BMI were more important influences on BMD than 25(OH)D or RA disease activity. The utility of measuring VDBP levels in this population remains uncertain.
    Study site: Rheumatology clinic, Hospital Tuanku Jaafar, Seremban, Negeri Semblance; Klinik Pakar Puchong, Puchong, Kuala Lumpur, Malaysia
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