Displaying publications 1 - 20 of 29 in total

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  1. Samuel S, Vadivelu J, Parasakthi N
    PMID: 9322293
    Amongst 107 diarrheal cases studied a bacterial agent was isolated from 71 (66%) cases of which 60 (85%) were due to a single agent and the remaining 11 (15%) were of mixed infections. Enterotoxigenic Escherichia coli (ETEC) was isolated from 65 cases. Other pathogens isolated included Salmonella spp, Shigella spp and rotavirus. There was a higher isolation rate of ETEC from females and rotavirus from males. The infection rate was found to higher for the 0-2 year age group as compared to the 3-5 year age group. Amongst the ETEC isolated the STa 2 toxotype was the predominant type.
  2. Wang B, Ngoi S, Wang J, Chong SS, Lee CG
    Mol. Pharmacol., 2006 Jul;70(1):267-76.
    PMID: 16608921
    The MDR1 multidrug transporter represents one of the better characterized drug transporters that play an important role in protecting the body against xenobiotic insults. Single nucleotide polymorphisms (SNPs) and SNP haplotypes within this gene have been variously associated with differences in MDR1 expression/function, drug response as well as disease susceptibility. Nonetheless, the effect of polymorphisms at the MDR1 promoter region on its promoter activity remains less characterized. Through the examination of approximately 1.5 kilobases of MDR1 promoter region from five populations, including the Chinese, Malays, Indians, European Americans, and African Americans, we identified eight low-frequency SNPs, of which only two were polymorphic in at least four of the five populations examined. The other SNPs are mainly population-specific, the majority of which occur only in the African-American population. Recapitulation of the various combinations of SNP haplotypes in vitro in promoter-reporter assays revealed a few notable trends. The African and European American-specific haplotypes tended to result in enhanced MDR1 promoter activity only in the human embryonic kidney (HEK) 293 cell line. Haplotype GCTAACC, which occurs at variable frequencies in all the populations examined, with Asians having much lower frequencies (<2%) compared with the European Americans/African Americans (>4%), affected MDR1 promoter activity differently in different cell lines. Compared with the commonest haplotype, GCTA-ACC haplotype resulted in a significant decrease in MDR1 promoter activity in HeLa cells (P < 0.05) but a significant increase in the same promoter activity in HEK293 cells (P < 0.05). These results suggest that the MDR1 promoter region is largely invariant but that different haplotypes have differential effects on the MDR1 promoter activity in different cell lines.
  3. Colangelo LA, Carroll AJ, Perak AM, Gidding SS, Lima JAC, Lloyd-Jones DM
    Psychosom Med, 2024 01 09;86(2):60-71.
    PMID: 38193784 DOI: 10.1097/PSY.0000000000001277
    OBJECTIVE: Depression is a risk factor for coronary heart disease and left ventricular hypertrophy (LVH) is a potent predictor of coronary heart disease events. Whether depression is associated with LVH has received limited investigation. This study assessed cross-sectional and 20-year longitudinal associations of depressive symptoms with LVH outcomes after accounting for important known confounders.

    METHODS: From 5115 participants enrolled in 1985-1986 in the Coronary Artery Risk Development in Young Adults Study, 2533 had serial measures of depressive symptoms and subsequent echocardiography to measure normal LV geometry, concentric remodeling, and LVH. The primary exposure variable was trajectories of the Center for Epidemiologic Studies Depression (CES-D) scale score from 1990-1991 to 2010-2011. Multivariable polytomous logistic regression was used to assess associations of trajectories with a composite LV geometry outcome created using echocardiogram data measured in 2010-2011 and 2015-2016. Sex-specific conflicting results led to exploratory models that examined potential importance of testosterone and sex hormone-binding globulin.

    RESULTS: Overall CES-D and Somatic subscale trajectories had significant associations with LVH for female participants only. Odds ratios for the subthreshold (mean CES-D ≈ 14) and stable (mean CES-D ≈ 19) groups were 1.49 (95% confidence interval = 1.05-2.13) and 1.88 (95% confidence interval = 1.16-3.04), respectively. For female participants, sex hormone-binding globulin was inversely associated with LVH, and for male participants, bioavailable testosterone was positively associated with concentric geometry.

    CONCLUSIONS: Findings from cross-sectional and longitudinal regression models for female participants, but not male ones, and particularly for Somatic subscale trajectories suggested a plausible link among depression, androgens, and LVH. The role of androgens to the depression-LVH relation requires additional investigation in future studies.

  4. Samuel S, Ahmad RE, Ramasamy TS, Manan F, Kamarul T
    Injury, 2018 Apr;49(4):775-783.
    PMID: 29503013 DOI: 10.1016/j.injury.2018.02.020
    BACKGROUND: It has been previously suggested that the use of regenerative promoters, which include bone marrow-derived mesenchymal stem cells (MSCs) or natural growth factors supplement such as platelet-rich concentrate (PRC) could promote cartilage regeneration. However, the notion that the concurrent use of both promoters may provide a synergistic effect that improves the repair outcome of focal cartilage injury has not been previously demonstrated. This study was thus conducted to determine whether the concomitant use of PRC could further enhance the reparative potential of MSCs encapsulated in alginate transplanted into focal cartilage injury in rabbits.

    METHODS: Artifically created full thickness cartilage defects were made on the weight-bearing region of medial femoral condyles in bilateral knees of New Zealand White rabbits (N = 30). After one month, the right knee was treated with either i) PRC (n = 10), ii) MSCs (n = 10), or, iii) a combination of PRC and MSCs (PRC + MSC) (n = 10), all encapsulated in alginate. The left knee remained untreated (control). Rabbits were sacrificed at 3 and 6 months after treatment. Cartilage tissue regeneration was accessed using ICRS morphologic scoring, histologic grading by O'Driscoll scoring, immunohistochemical staining and quantitative analysis of glycosaminoglycans (GAG) per total protein content.

    RESULTS: At 3 months, transplantation using PRC alone was equally effective as MSCs in inducing the repair of cartilage defects. However, PRC + MSC resulted in significantly higher ICRS and O'Driscoll scores (p 

  5. Tang K, Ngoi SM, Gwee PC, Chua JM, Lee EJ, Chong SS, et al.
    Pharmacogenetics, 2002 Aug;12(6):437-50.
    PMID: 12172212
    The MDR1 multidrug transporter plays a key role in determining drug bioavailability, and differences in drug response exist amongst different ethnic groups. Numerous studies have identified an association between the MDR1 single nucleotide polymorphism (SNP) exon 26 3435C>T and differences in MDR1 function. We performed a haplotype analysis of the MDR1 gene in three major ethnic groups (Chinese, Malays and Indians) by examining 10 intragenic SNPs. Four were polymorphic in all three ethnic groups: one occurring in the non-coding region and three occurring in coding exons. All three coding SNPs (exon 12 1236C>T, exon 21 2677G>T/A and exon 26 3435C>T) were present in high frequency in each ethnic group, and the derived haplotype profiles exhibited distinct differences between the groups. Fewer haplotypes were observed in the Malays (n = 6) compared to the Chinese (n = 10) and Indians (n = 9). Three major haplotypes (> 10% frequency) were observed in the Malays and Chinese; of these, two were observed in the Indians. Strong linkage disequilibrium (LD) was detected between the three SNPs in all three ethnic groups. The strongest LD was present in the Chinese, followed by Indians and Malays, with the corresponding LD blocks estimated to be approximately 80 kb, 60 kb and 40 kb, respectively. These data strongly support the hypothesis that strong LD between the neutral SNP exon 26 3435C>T and a nearby unobserved causal SNP underlies the observed associations between the neutral SNP and MDR1 functional differences. Furthermore, strong LD between exon 26 3435T and different unobserved causal SNPs in different study populations may provide a plausible explanation for conflicting reports associating the same exon 26 3435T allele with different MDR1 functional changes.
  6. Aravind SR, Ismail SB, Balamurugan R, Gupta JB, Wadhwa T, Loh SM, et al.
    Curr Med Res Opin, 2012 Aug;28(8):1289-96.
    PMID: 22738801 DOI: 10.1185/03007995.2012.707119
    To compare the incidence of symptomatic hypoglycemia between sitagliptin and sulfonylurea in Muslim patients with type 2 diabetes who fasted during Ramadan.
  7. Perak AM, Khan SS, Colangelo LA, Gidding SS, Armstrong AC, Lewis CE, et al.
    J Am Soc Echocardiogr, 2021 04;34(4):388-400.
    PMID: 33212181 DOI: 10.1016/j.echo.2020.11.002
    BACKGROUND: Little is known about the timing of preclinical heart failure (HF) development, particularly among blacks. The primary aims of this study were to delineate age-related left ventricular (LV) structure and function evolution in a biracial cohort and to test the hypothesis that young-adult LV parameters within normative ranges would be associated with incident stage B-defining LV abnormalities over 25 years, independent of cumulative risk factor burden.

    METHODS: Data from the Coronary Artery Risk Development in Young Adults study were analyzed. Participants (n = 2,833) had a mean baseline age of 30.1 years; 45% were black, and 56% were women. Generalized estimating equation logistic regression was used to estimate age-related probabilities of stage B LV abnormalities (remodeling, hypertrophy, or dysfunction) and logistic regression to examine risk factor-adjusted associations between baseline LV parameters and incident abnormalities. Cox regression was used to assess whether baseline LV parameters associated with incident stage B LV abnormalities were also associated with incident clinical (stage C/D) HF events over >25 years' follow-up.

    RESULTS: Probabilities of stage B LV abnormalities at ages 25 and 60 years were 10.5% (95% CI, 9.4%-11.8%) and 45.0% (95% CI, 42.0%-48.1%), with significant race-sex disparities (e.g., at age 60, black men 52.7% [95% CI, 44.9%-60.3%], black women 59.4% [95% CI, 53.6%-65.0%], white men 39.1% [95% CI, 33.4%-45.0%], and white women 39.1% [95% CI, 33.9%-44.6%]). Over 25 years, baseline LV end-systolic dimension indexed to height was associated with incident systolic dysfunction (adjusted odds ratio per 1 SD higher, 2.56; 95% CI, 1.87-3.52), eccentric hypertrophy (1.34; 95% CI, 1.02-1.75), concentric hypertrophy (0.69; 95% CI, 0.51-0.91), and concentric remodeling (0.68; 95% CI, 0.58-0.79); baseline LV mass indexed to height2.7 was associated with incident eccentric hypertrophy (1.70; 95% CI, 1.25-2.32]), concentric hypertrophy (1.63; 95% CI, 1.19-2.24), and diastolic dysfunction (1.24; 95% CI, 1.01-1.52). Among the entire cohort with baseline echocardiographic data available (n = 4,097; 72 HF events), LV end-systolic dimension indexed to height and LV mass indexed to height2.7 were significantly associated with incident clinical HF (adjusted hazard ratios per 1 SD higher, 1.56 [95% CI, 1.26-1.93] and 1.42 [95% CI, 1.14-1.75], respectively).

    CONCLUSIONS: Stage B LV abnormalities and related racial disparities were present in young adulthood, increased with age, and were associated with baseline variation in indexed LV end-systolic dimension and mass. Baseline indexed LV end-systolic dimension and mass were also associated with incident clinical HF. Efforts to prevent the LV abnormalities underlying clinical HF should start from a young age.

  8. Marlier ME, Liu T, Yu K, Buonocore JJ, Koplitz SN, DeFries RS, et al.
    Geohealth, 2019 Jul;3(7):178-189.
    PMID: 32159040 DOI: 10.1029/2019GH000191
    Emissions of particulate matter from fires associated with land management practices in Indonesia contribute to regional air pollution and mortality. We assess the public health benefits in Indonesia, Malaysia, and Singapore from policies to reduce fires by integrating information on fire emissions, atmospheric transport patterns, and population exposure to fine particulate matter (PM2.5). We use adjoint sensitivities to relate fire emissions to PM2.5 for a range of meteorological conditions and find that a Business-As-Usual scenario of land use change leads, on average, to 36,000 excess deaths per year into the foreseeable future (the next several decades) across the region. These deaths are largely preventable with fire reduction strategies, such as blocking fires in peatlands, industrial concessions, or protected areas, which reduce the health burden by 66, 45, and 14%, respectively. The effectiveness of these different strategies in mitigating human health impacts depends on the location of fires relative to the population distribution. For example, protecting peatlands through eliminating all fires on such lands would prevent on average 24,000 excess deaths per year into the foreseeable future across the region because, in addition to storing large amounts of fuel, many peatlands are located directly upwind of densely populated areas. We also demonstrate how this framework can be used to prioritize restoration locations for the Indonesian Peatland Restoration Agency based on their ability to reduce pollution exposure and health burden. This scientific framework is publicly available through an online decision support tool that allows stakeholders to readily determine the public health benefits of different land management strategies.
  9. Karunanithi P, Murali MR, Samuel S, Raghavendran HRB, Abbas AA, Kamarul T
    Carbohydr Polym, 2016 08 20;147:294-303.
    PMID: 27178935 DOI: 10.1016/j.carbpol.2016.03.102
    Presence of sulfated polysaccharides like heparan sulphate has often been implicated in the regulation of chondrogenesis. However, recently there has been a plethora of interest in the use of non-animal extracted analogs of heparan sulphate. Here we remodeled alginate (1.5%) by incorporating fucoidan (0.5%), a natural sulphated polysaccharide extracted from seaweeds to form a composite hydrogel (Al-Fu), capable of enhancing chondrogenesis of human mesenchymal stromal cells (hMSCs). We confirmed the efficiency of fucoidan incorporation by FTIR and EDX analysis. Further, its ability to support hMSC attachment and chondrogenic differentiation was confirmed by SEM, biochemical glycosaminoglycan quantification, real-time quantitative PCR and immunocytochemical analyses of chondrogenic markers Sox-9, Collagen II, Aggrecan and COMP. Effect of Al-Fu hydrogel on hMSC hypertrophy was also confirmed by the downregulation of hypertrophic genes Collagen X and Runx2. This composite scaffold can hence be used as a cartilage biomimetic biomaterial to drive hMSC chondrogenesis and for other cartilage repair based therapies.
  10. Pourshahrestani S, Zeimaran E, Adib Kadri N, Gargiulo N, Samuel S, Naveen SV, et al.
    J Mater Chem B, 2016 Jan 07;4(1):71-86.
    PMID: 32262810 DOI: 10.1039/c5tb02062j
    Haemorrhage remains the leading cause of potentially survivable death in both military and civilian populations. Although a large variety of hemostatic agents have been developed, many of them have an inadequate capacity to induce hemostasis and are not effective in killing bacteria. In recent years, mesoporous bioactive glasses (MBGs) were found to be effective in inducing hemostasis. However, the materials may not be considered as ideal hemostats since they do not offer antimicrobial activity. The gallium ion (Ga+3) not only exhibits antibacterial properties but also accelerates the blood coagulation cascade. The aim of this study was to develop MBGs containing various concentrations of Ga2O3 (1, 2 & 3 mol%) via the evaporation-induced self-assembly (EISA) process and investigate whether the addition of Ga3+ would induce both hemostatic and antibacterial effects. The results indicated that the incorporation of lower Ga2O3 content (1 mol%) into the MBG system improved structural properties including the specific surface area, mesopore size and pore volume as well as the release of silicon and calcium ions. The bioactive glass was found to stimulate blood coagulation, platelet adhesion and thrombus generation and exerted an antibacterial effect against both Escherichia coli and Staphylococcus aureus. Likewise, Ga-doped MBGs showed excellent cytocompatibility even after 3 days, with the 1% Ga2O3-containing MBG attaining the best biocompatibility that render them safe hemostatic agents for stopping bleeding. This study demonstrated that the lowest Ga2O3-substituted MBG can be a potent candidate for controlling haemorrhage and wound infection.
  11. Samuel S, Ahmad RE, Ramasamy TS, Karunanithi P, Naveen SV, Kamarul T
    Platelets, 2019;30(1):66-74.
    PMID: 29090639 DOI: 10.1080/09537104.2017.1371287
    Platelet-rich concentrate (PRC), used in conjunction with other chondroinductive growth factors, have been shown to induce chondrogenesis of human mesenchymal stromal cells (hMSC) in pellet culture. However, pellet culture systems promote cell hypertrophy and the presence of other chondroinductive growth factors in the culture media used in previous studies obscures accurate determination of the effect of platelet itself in inducing chondrogenic differentiation. Hence, this study aimed to investigate the effect of PRC alone in enhancing the chondrogenic differentiation potential of human mesenchymal stromal cells (hMSC) encapsulated in three-dimensional alginate constructs. Cells encapsulated in alginate were cultured in serum-free medium supplemented with only 15% PRC. Scanning electron microscopy was used to determine the cell morphology. Chondrogenic molecular signature of hMSCs was determined by quantitative real-time PCR and verified at protein levels via immunohistochemistry and enzyme-linked immunosorbent assay. Results showed that the cells cultured in the presence of PRC for 24 days maintained a chondrocytic phenotype and demonstrated minimal upregulation of cartilaginous extracellular matrix (ECM) marker genes (SOX9, TNC, COL2, ACAN, COMP) and reduced expression of chondrocyte hypertrophy genes (Col X, Runx2) compared to the standard chondrogenic medium (p 
  12. Aravind SR, Al Tayeb K, Ismail SB, Shehadeh N, Kaddaha G, Liu R, et al.
    Curr Med Res Opin, 2011 Jun;27(6):1237-42.
    PMID: 21506631 DOI: 10.1185/03007995.2011.578245
    To determine the incidence of hypoglycaemia during Ramadan in Muslim subjects with type 2 diabetes treated with a sulphonylurea.
  13. Shankar RR, Zeitler P, Deeb A, Jalaludin MY, Garcia R, Newfield RS, et al.
    Pediatr Diabetes, 2022 Mar;23(2):173-182.
    PMID: 34779087 DOI: 10.1111/pedi.13279
    OBJECTIVE: To assess the efficacy and safety of DPP-4 inhibition with sitagliptin in youth with type 2 diabetes (T2D).

    STUDY DESIGN: This was a 54-week, double-blind, randomized, controlled clinical trial evaluating the safety and efficacy of DPP-4 inhibition with sitagliptin 100 mg once daily as initial oral therapy in youth with T2D. The 190 participants, aged 10-17 years, had HbA1c 6.5%-10% (7.0%-10% if on insulin). All were negative for pancreatic autoantibodies and overweight/obese at screening or diagnosis. The trial was placebo controlled for the first 20 weeks, after which metformin replaced placebo. The primary efficacy endpoint was change from baseline in HbA1c at Week 20.

    RESULTS: Treatment groups were well balanced at baseline (mean ± SD HbA1c = 7.5% ± 1.0, BMI percentile = 97.1% ± 6.8, age = 14.0 years ± 2.0 [57.4% <15], 60.5% female). At Week 20, least squares mean changes from baseline in HbA1c were -0.01% (sitagliptin) and 0.18% (placebo); between-group difference (95% CI) = -0.19% (-0.68, 0.30), p = 0.448. At Week 54, the changes in HbA1c were 0.45% (sitagliptin) and -0.11 (placebo/metformin). There were no notable between-group differences in the adverse event profiles through Week 54.

    CONCLUSIONS: DPP-4 inhibition with sitagliptin did not provide significant improvement in glycemic control. In this study, sitagliptin was generally well tolerated with a safety profile similar to that reported in adults. (ClinicalTrials.gov: NCT01485614; EudraCT: 2011-002528-42).

  14. Jalaludin MY, Deeb A, Zeitler P, Garcia R, Newfield RS, Samoilova Y, et al.
    Pediatr Diabetes, 2022 Mar;23(2):183-193.
    PMID: 34779103 DOI: 10.1111/pedi.13282
    OBJECTIVE: To assess the efficacy and safety of sitagliptin in youth with type 2 diabetes (T2D) inadequately controlled with metformin ± insulin.

    STUDY DESIGN: Data were pooled from two 54-week, double-blind, randomized, placebo-controlled studies of sitagliptin 100 mg daily or placebo added onto treatment of 10- to 17-year-old youth with T2D and inadequate glycemic control on metformin ± insulin. Participants (N = 220 randomized and treated) had HbA1c 6.5%-10% (7.0%-10% if on insulin), were overweight/obese at screening or diagnosis and negative for pancreatic autoantibodies. The primary endpoint was change from baseline in HbA1c at Week 20.

    RESULTS: Treatment groups were well balanced at baseline (mean HbA1c = 8.0%, BMI = 30.9 kg/m2 , age = 14.4 years [44.5% <15], 65.9% female). The dose of background metformin was >1500 mg/day for 71.8% of participants; 15.0% of participants were on insulin therapy. At Week 20, LS mean changes from baseline (95% CI) in HbA1c for sitagliptin/metformin and placebo/metformin were -0.58% (-0.94, -0.22) and -0.09% (-0.43, 0.26), respectively; difference = -0.49% (-0.90, -0.09), p = 0.018; at Week 54 the LS mean (95% CI) changes were 0.35% (-0.48, 1.19) and 0.73% (-0.08, 1.54), respectively. No meaningful differences between the adverse event profiles of the treatment groups emerged through Week 54.

    CONCLUSIONS: These results do not suggest that addition of sitagliptin to metformin provides durable improvement in glycemic control in youth with T2D. In this study, sitagliptin was generally well tolerated with a safety profile similar to that reported in adults. (ClinicalTrials.gov: NCT01472367, NCT01760447; EudraCT: 2011-002529-23/2014-003583-20, 2012-004035-23).

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