Displaying publications 321 - 340 of 673 in total

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  1. Al-Wabli RI, El-Emam AA, Alroqi OS, Chidan Kumar CS, Fun HK
    Acta Crystallogr E Crystallogr Commun, 2015 Feb 1;71(Pt 2):o115-6.
    PMID: 25878859 DOI: 10.1107/S2056989015000596
    The title compound, C18H20ClN3S, is a functionalized triazoline-3-thione derivative. The benzene ring is almost perpendic-ular to the planar 1,2,4-triazole ring [maximum deviation = 0.007 (1) Å] with a dihedral angle of 89.61 (5)° between them and there is an adamantane substituent at the 3-position of the triazole-thione ring. In the crystal, N-H⋯S hydrogen-bonding inter-actions link the mol-ecules into chains extending along the c-axis direction. The crystal packing is further stabilized by weak C-H⋯π inter-actions that link adjacent chains into a two-dimensional structure in the bc plane. The crystal studied was an inversion twin with a 0.50 (3):0.50 (3) domain ratio.
  2. Bagabas AA, Alhoshan SB, Ghabbour HA, Chidan Kumar CS, Fun HK
    Acta Crystallogr E Crystallogr Commun, 2015 Jan 1;71(Pt 1):o62-3.
    PMID: 25705511 DOI: 10.1107/S2056989014027297
    In the title salt, C6H11NH3 (+)·SCN(-), the cyclo-hexyl-ammonium ring adopts a slightly distorted chair conformation. The ammonium group occupies an equatorial position to minimize 1,3 and 1,5 diaxial inter-actions. In the crystal, the components are linked by N-H⋯N and N-H⋯S hydrogen-bonding inter-actions, resulting in a three-dimensional network.
  3. Ghalib RM, Chidan Kumar CS, Hashim R, Sulaiman O, Fun HK
    Acta Crystallogr E Crystallogr Commun, 2015 Jan 1;71(Pt 1):o6-7.
    PMID: 25705509 DOI: 10.1107/S2056989014025997
    In the title iso-quinoline-1,3,4-trione derivative, C18H9NO5, the five-membered ring of the indane fragment adopts an envelope conformation with the nitro-gen-substituted C atom being the flap. The planes of the indane benzene ring and the iso-quinoline-1,3,4-trione ring make a dihedral angle of 82.06 (6)°. In the crystal, mol-ecules are linked into chains extending along the bc plane via C-H⋯O hydrogen-bonding inter-actions, enclosing R 2 (2)(8) and R 2 (2)(10) loops. The chains are further connected by π-π stacking inter-ations, with centroid-to-centroid distances of 3.9050 (7) Å, forming layers parallel to the b axis.
  4. Alzoman NZ, El-Emam AA, Ghabbour HA, Chidan Kumar CS, Fun HK
    Acta Crystallogr Sect E Struct Rep Online, 2014 Dec 01;70(Pt 12):o1231-2.
    PMID: 25553016 DOI: 10.1107/S1600536814023861
    In the title mol-ecule, C18H19BrN2O, the benzene ring is inclined to the oxa-diazole ring by 10.44 (8)°. In the crystal, C-H⋯π inter-actions link the mol-ecules in a head-to-tail fashion, forming chains extending along the c-axis direction. The chains are further connected by π-π stacking inter-actions, with centroid-centroid distances of 3.6385 (7) Å, forming layers parallel to the bc plane.
  5. El-Emam AA, Al-Abdullah ES, Al-Tuwaijri HM, Chidan Kumar CS, Fun HK
    Acta Crystallogr Sect E Struct Rep Online, 2013 Nov 23;69(Pt 12):o1815.
    PMID: 24454244 DOI: 10.1107/S1600536813031516
    In the title compound, C20H26N2S, the N-containing six-membered ring adopts a boat conformation and the dihedral angle between the thio-carbamide group and the benzene ring is 49.67 (9)°. An intra-molecular C-H⋯S hydrogen bond generates an S(6) ring motif. The N-H group is sterically hindered and there are no significant inter-molecular inter-actions beyond van der Waals contacts.
  6. Al-Abdullah ES, Al-Tuwaijri HM, El-Emam AA, Chidan Kumar CS, Fun HK
    Acta Crystallogr Sect E Struct Rep Online, 2013 Nov 23;69(Pt 12):o1813-4.
    PMID: 24454243 DOI: 10.1107/S1600536813031127
    In the title compound, C26H37N5S, the piperazine ring adopts a chair conformation with the exocyclic N-C bonds in pseudo-equatorial orientations. The piperazine ring (all atoms) subtends dihedral angles of 79.47 (9) and 73.07 (9)° with the triazole and benzene rings, respectively, resulting in an approximate U-shape for the mol-ecule. No significant inter-molecular inter-actions are observed in the crystal.
  7. Fun HK, Chantrapromma S, Ruanwas P, Kobkeatthawin T, Chidan Kumar CS
    Acta Crystallogr Sect E Struct Rep Online, 2014 Jan 1;70(Pt 1):o89-90.
    PMID: 24527018 DOI: 10.1107/S1600536813033989
    The mol-ecule of the title hydrazine derivative, C15H14N4O6, is essentially planar, the dihedral angle between the substituted benzene rings being 2.25 (9)°. The eth-oxy and hy-droxy groups are almost coplanar with their bound benzene ring [r.m.s. deviation = 0.0153 (2) Å for the ten non-H atoms]. Intra-molecular N-H⋯O and O-H⋯Oeth-oxy hydrogen bonds generate S(6) and S(5) ring motifs, respectively. In the crystal, mol-ecules are linked by O-H⋯Onitro hydrogen bonds into chains propagating in [010]. Weak aromatic π-π inter-actions, with centroid-centroid distances of 3.8192 (19) and 4.0491 (19) Å, are also observed.
  8. El-Emam AA, Al-Tuwaijri HM, Al-Abdullah ES, Chidan Kumar CS, Fun HK
    Acta Crystallogr Sect E Struct Rep Online, 2014 Jan 01;70(Pt 1):o25-6.
    PMID: 24526973 DOI: 10.1107/S1600536813032789
    In the title compound, C26H37N5OS, the piperazine ring adopts a chair conformation. The triazole ring forms dihedral angles of 67.85 (9) and 59.41 (9)° with the piperazine and benzene rings, respectively, resulting in an approximate V-shaped conformation for the mol-ecule. An intra-molecular C-H⋯O hydrogen bond generates an S(6) ring motif. The crystal structure features C-H⋯π inter-actions, producing a two-dimensional supramolecular architecture.
  9. Chidan Kumar CS, Fun HK, Tursun M, Ooi CW, Chandraju S, Quah CK, et al.
    Spectrochim Acta A Mol Biomol Spectrosc, 2014 Apr 24;124:595-602.
    PMID: 24509537 DOI: 10.1016/j.saa.2014.01.063
    2-(4-Chlorophenyl)-2-oxoethyl 2-chlorobenzoate has been synthesized, its structural and vibrational properties have been reported using FT-IR and single-crystal X-ray diffraction (XRD) studies. The conformational analysis, optimized geometric parameters, normal mode frequencies and corresponding vibrational assignments of the synthesized compound (C15H10Cl2O3) have been examined by means of Becke-3-Lee-Yang-Parr (B3LYP) density functional theory (DFT) method together with 6-31++G(d,p) basis set. Furthermore, reliable conformational investigation and vibrational assignments have been made by the potential energy surface (PES) and potential energy distribution (PED) analyses, respectively. Calculations are performed with two possible conformations. The title compound crystallizes in orthorhombic space group Pbca with the unit cell dimensions a=12.312(5) Å, b=8.103(3) Å, c=27.565(11) Å, V=2750.0(19) Å(3). B3LYP method provides satisfactory evidence for the prediction of vibrational wavenumbers and structural parameters.
  10. Kumar CS, Loh WS, Ooi CW, Quah CK, Fun HK
    Molecules, 2013 Oct 15;18(10):12707-24.
    PMID: 24132195 DOI: 10.3390/molecules181012707
    Chalcone derivatives have attracted increasing attention due to their numerous pharmacological activities. Changes in their structures have displayed high degree of diversity that has proven to result in a broad spectrum of biological activities. The present study highlights the synthesis of some halogen substituted chalcones 3(a-i) containing the 5-chlorothiophene moiety, their X-ray crystal structures and the evaluation of possible biological activities such as antibacterial, antifungal and reducing power abilities. The results indicate the tested compounds show a varied range of inhibition values against all the tested microbial strains. Compound 3c with a p-fluoro substituent on the phenyl ring exhibits elevated antimicrobial activity, whereas the compounds 3e and 3f displayed the least antimicrobial activities. The compounds 3d, 3e, 3f and 3i showed good ferric and cupric reducing abilities, and the compounds 3b and 3c showed the weakest reducing power in the series.
  11. Kumar CS, Loh WS, Ooi CW, Quah CK, Fun HK
    Molecules, 2013 Sep 26;18(10):11996-2011.
    PMID: 24077177 DOI: 10.3390/molecules181011996
    A series of six novel heterocyclic chalcone analogues 4(a-f) has been synthesized by condensing 2-acetyl-5-chlorothiophene with benzaldehyde derivatives in methanol at room temperature using a catalytic amount of sodium hydroxide. The newly synthesized compounds are characterized by IR, mass spectra, elemental analysis and melting point. Subsequently; the structures of these compounds were determined using single crystal X-ray diffraction. All the synthesized compounds were screened for their antioxidant potential by employing various in vitro models such as DPPH free radical scavenging assay, ABTS radical scavenging assay, ferric reducing antioxidant power and cupric ion reducing antioxidant capacity. Results reflect the structural impact on the antioxidant ability of the compounds. The IC₀ values illustrate the mild to good antioxidant activities of the reported compounds. Among them, 4f with a p-methoxy substituent was found to be more potent as antioxidant agent.
  12. Fun HK, Chidan Kumar CS, Patrao P, Khader AM, Kalluraya B
    Acta Crystallogr Sect E Struct Rep Online, 2013 Apr 1;69(Pt 4):o491-2.
    PMID: 23634043 DOI: 10.1107/S1600536813005837
    The asymmetric unit of the title compound, C26H18N6O4S, contains two independent mol-ecules (A and B). The dihedral angles between the oxadiazole ring and naphthalene ring system are 42.59 (14) and 6.88 (14) Å in mol-ecules A and B, respectively. The dihedral angles between the pyridine and benzene rings in A and B are 65.53 (13 )and 87.67 (13) Å, respectively. In the crystal, mol-ecules A and B are linked through a pair of N-H⋯N hydrogen bonds involving one -NH2 group H atom and second pair of N-H⋯N hydrogen bonds involving the other -NH2 group H atom, forming an -ABAB- ribbon along [100] containing R 2 (2)(8) and R 2 (2)(12) ring motifs. These ribbons are further connected by weak C-H⋯N, C-H⋯O and C-H⋯π inter-actions, resulting in a three-dimensional network. The crystal studied was a non-merohedral twin with refined components 0.906 (1):0.094 (1).
  13. Chew LL, Chong VC, Wong RCS, Lehette P, Ng CC, Loh KH
    Mar Pollut Bull, 2015 Dec 15;101(1):69-84.
    PMID: 26581817 DOI: 10.1016/j.marpolbul.2015.11.022
    Zooplankton samples collected before (1985-86) and after (2013-14) the establishment of Kapar power station (KPS) were examined to test the hypothesis that increased sea surface temperature (SST) and other water quality changes have altered the zooplankton community structure. Elevated SST and reduced pH were detected between before and after impact pairs, with the greatest impact at the station closest to KPS. Present PAHs and heavy metal concentrations are unlikely causal factors. Water parameter changes did not affect diversity but community structure of the zooplankton. Tolerant small crustaceans, salps and larvaceans likely benefited from elevated temperature, reduced pH and shift to a more significant microbial loop exacerbated by eutrophication, while large crustaceans were more vulnerable to such changes. It is predicted that any further rise in SST will remove more large-bodied crustacean zooplankton, the preferred food for fish larvae and other meroplankton, with grave consequences to fishery production.
  14. Koh MT, Liu CS, Chiu CH, Boonsawat W, Watanaveeradej V, Abdullah N, et al.
    Epidemiol Infect, 2016 Apr;144(6):1192-200.
    PMID: 26468043 DOI: 10.1017/S0950268815002393
    Surveillance data on the burden of pertussis in Asian adults are limited. This cross-sectional study evaluated the prevalence of serologically confirmed pertussis in adults with prolonged cough in Malaysia, Taiwan and Thailand. Adults (⩾19 years) with cough lasting for ⩾14 days without other known underlying cause were enrolled from outpatient clinics of seven public and/or private hospitals. Single blood samples for anti-pertussis toxin antibodies (anti-PT IgG) were analysed and economic impact and health-related quality of life (EQ-5D) questionnaires assessed. Sixteen (5·13%) of the 312 chronically coughing adults had serological evidence of pertussis infection within the previous 12 months (anti-PT IgG titre ⩾62·5 IU/ml). Three of them were teachers. Longer duration of cough, paroxysms (75% seroconfirmed, 48% non-seroconfirmed) and breathlessness/chest pain (63% seroconfirmed, 36% non-seroconfirmed) were associated with pertussis (P < 0·04). Of the seroconfirmed patients, the median total direct medical cost per pertussis episode in public hospitals (including physician consultations and/or emergency room visits) was US$13 in Malaysia, US$83 in Taiwan (n = 1) and US$26 in Thailand. The overall median EQ-5D index score of cases was 0·72 (range 0·42-1·00). Pertussis should be considered in the aetiology of adults with a prolonged or paroxysmal cough, and vaccination programmes considered.
    Study site in Malaysia: Klinik Kesihatan Seremban, Negeri Sembilan; Primary Care Clinic, University Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia
  15. Lim AC, Chong VC, Chew WX, Muniandy SV, Wong CS, Ong ZC
    J Acoust Soc Am, 2015 Jul;138(1):404-12.
    PMID: 26233039 DOI: 10.1121/1.4923153
    Acoustic signals of the tiger-tail seahorse (Hippocampus comes) during feeding were studied using wavelet transform analysis. The seahorse "click" appears to be a compounded sound, comprising three acoustic components that likely come from two sound producing mechanisms. The click sound begins with a low-frequency precursor signal, followed by a sudden high-frequency spike that decays quickly, and a final, low-frequency sinusoidal component. The first two components can, respectively, be traced to the sliding movement and forceful knock between the supraorbital bone and coronet bone of the cranium, while the third one (purr) although appearing to be initiated here is produced elsewhere. The seahorse also produces a growling sound when under duress. Growling is accompanied by the highest recorded vibration at the cheek indicating another sound producing mechanism here. The purr has the same low frequency as the growl; both are likely produced by the same structural mechanism. However, growl and purr are triggered and produced under different conditions, suggesting that such "vocalization" may have significance in communication between seahorses.
  16. Puthiaparampil T, Rahman MM, Shazrina AR, Nariman S, Lukas S, Chai CS, et al.
    Med J Malaysia, 2022 Nov;77(6):724-729.
    PMID: 36448391
    INTRODUCTION: Our faculty used one long case (LC) and three short cases for the clinical component of the final professional examinations. During the COVID-19 pandemic, the LC had to be replaced with scenario-based clinical examination (SBCE) due to the impracticability of using recently hospitalised patients. While keeping the short case component as usual, the LC had to be replaced with SBCE in 2020 for the first time at a short notice. To evaluate the positive and negative aspects of SBCE and LC to determine the feasibility of replacing LC with SBCE in future examinations.

    MATERIALS AND METHODS: We compared the LC scores of three previous years with those of the SBCE and studied the feedback of the three stakeholders: students, examiners, and simulated patients (SPs), regarding their experience with SBCE and the suitability of SBCE as an alternative for LC in future examinations.

    RESULTS: The SBCE scores were higher than those of the LC. Most of the examiners and students were not in favour of SBCE replacing LC, as such. The SPs were more positive about the proposition. The comments of the three stakeholders brought out the plus and minus points of LC and SBCE, which prompted our proposals to make SBCE more practical for future examinations.

    CONCLUSION: Having analysed the feedback of the stakeholders, and the positive and negative aspects of LC and SBCE, it was evident that SBCE needed improvements. We have proposed eight modifications to SBCE to make it a viable alternative for LC.

  17. Ngu NH, Chai CS, Chan SK, Kho SS, Yong MC, Tie ST
    Med J Malaysia, 2022 Nov;77(6):650-654.
    PMID: 36448380
    INTRODUCTION: Corticosteroids, particularly methylprednisolone, are part of the treatment for severe COVID-19 with acute respiratory distress syndrome (ARDS). In this study, we aimed to compare the mortalities of patients treated with higher versus lower doses of methylprednisolone. Secondary outcomes included oxygenation, need for mechanical ventilation, length of stay in intensive care unit (ICU), secondary infection, improvement of PaO2/FiO2 (PF) ratio, and inflammatory response as expressed by C-reactive protein (CRP).

    MATERIALS AND METHODS: A retrospective cohort study conducted at Sarawak General Hospital from 1st June to 30th September 2021. Patients who received intravenous methylprednisolone for severe COVID-19 in the ICU were identified and divided into two groups: higher dose (cumulative dose more than 10 mg per kg) and lower dose (cumulative dose less than 10 mg per kg).

    RESULTS: Out of a total of 165 patients, 40 (24.2%) patients received higher dose methylprednisolone. There was no significant difference in socio-demographic characteristics (age, gender, body mass index), COVID-19 vaccination status, laboratory parameters (lymphocyte count, CRP, lactate dehydrogenase, D-dimer), or usage of immunomodulator therapy between the groups. Overall mortality was 23.6%. Mortality in the higher dose group was twice as high compared to lower dose group (37.5% versus 19.2%) (OR 3.79, 95% CI 1.24-11.59, p<0.05). In addition, the higher dose cohort developed more secondary infections (87.5%) and had longer stays in ICU (median 11 days, IQR 8- 15). No significant difference was found between both cohorts in terms of CRP reduction, improvement of PF ratio, or the need for mechanical ventilation post methylprednisolone.

    CONCLUSION: In this study, the use of higher dose methylprednisolone in COVID-19 with ARDS was not associated with better clinical outcomes. A lower dose of methylprednisolone might be sufficient in treating severe COVID-19 with ARDS.

  18. Sankar A, Kandasamy D, Jones S, Radhakrishan A, Janaki CS, Sheriff D, et al.
    J Pharm Bioallied Sci, 2024 Apr;16(Suppl 2):S1824-S1828.
    PMID: 38882815 DOI: 10.4103/jpbs.jpbs_9_24
    BACKGROUND: Neurodegenerative diseases induce amnesia, and effective treatment is still elusive. Aims and Objectives: The present study highlights the ameliorating effects of Manasa Mitra Vatakam (MMV) using behavioral parameters on scopolamine-induced memory loss in female Wistar rats.

    MATERIALS AND METHODS: MMV was compared with DPZ as a standard in the present study to determine the behavioral parameters through elevated plus maze (Hebb William maze/rectangular maze)and locomotor activity in scopolamine-induced memory loss in female Wistar rats.

    RESULTS AND DISCUSSION: The results of the study illustrate the effectiveness of MMV in reversing memory dysfunction and memory-enhancing effects.

    CONCLUSION: The study paves the way for exploring research in CNS disorders and its potential application in drug-induced neurotoxicity.

  19. Khor CS, Lee HY, Abd-Majid MA, Khoo HY, Khoo JJ, AbuBakar S
    Trop Biomed, 2024 Jun 01;41(2):224-229.
    PMID: 39154278 DOI: 10.47665/tb.41.2.015
    Serological evidence has shown the presence of several mosquito-borne arbovirus infections among the inhabitants of the forest fringe areas of the tropics. Among these infections, Japanese encephalitis, dengue fever, chikungunya fever and Zika fever could be targeted for vaccination to overcome severe infection and limit the disease transmission. Seroprevalence data among this high-risk population are needed to provide an estimate of the potential cost-effectiveness of any vaccine programme targeting these infections. The present study was conducted at six indigenous people (Orang Asli) villages and FELDA (Federal Land Development Authority) settlements located at the forest fringes of Malaysia. All participants consented and provided blood samples and demographic data for the study. The blood samples were tested for the presence of antibodies against CHIKV, DENV, JEV and ZIKV individually using ELISA. Results obtained were also analysed to determine the predictors for CHIKV, DENV, JEV and ZIKV seropositivity. Among the 585 samples tested, 33.0% (N=193), 41.7% (N=244), 10.3% (N=60) and 21.0% (N=123) were positive for CHIKV IgG, DENV IgG, JEV IgG and ZIKV IgG, respectively. Approximately one-third (N=220, 37.6%) of the participants were tested negative for IgG antibodies against all four arboviruses. Age of participants and type of settlement were found to be a significant predictor for CHIKV, DENV, JEV and ZIKV seropositivity. Level of education was a significant predictor for CHIKV, DENV and ZIKV seropositivity. Gender, however, was not found to be a significant predictor for infection with any of these viruses. These findings reaffirmed the significant presence of infection involving these major arboviruses among the group of people living within the forest fringe areas of Peninsular Malaysia. Hence, any future consideration of vaccination for these infections must take into consideration the marginalized and underserved communities living at the forest fringe areas of the tropics where these infections are present.
  20. Muhammad M, Loong SK, Khor CS, Mohd-Azami SNI, Kafle A, Useh U, et al.
    Trop Biomed, 2024 Mar 01;41(1):78-83.
    PMID: 38852137 DOI: 10.47665/tb.41.1.010
    The present study aimed at exploring whether sunlight exposure might account for the relative difference in COVID-19-related morbidity and mortality between tropical and non-tropical countries. A retrospective observational study was designed and data from the World Health Organization weekly COVID-19 epidemiological update was compiled. We examined the total number of confirmed COVID-19 cases per 100 000 population, as well as the total number of COVID-19-related mortalities per 100 000 population. Solar variables data were obtained from the Global Solar Atlas website (https://globalsolaratlas.info/). These data were analyzed to determine the association of sunlight exposure to COVID-19-related morbidity and mortality in tropical and non-tropical countries. Results revealed a statistically significant decrease in the number of confirmed COVID-19 cases per 100 000 population (P<0.001), as well as the number of COVID-19-related mortalities per 100 000 population (P<0.001) between tropical and non-tropical countries. Analyses of sunlight exposure data found that specific photovoltaic power output, global horizontal irradiation, diffuse horizontal irradiation and global tilted irradiation at optimum angle were significantly inversely correlated to COVID-19-related morbidity and mortality. This suggests that stronger sunlight exposure potentially leads to lower COVID-19-related morbidity and mortality. Findings from this study suggest that the relatively low COVID-19-related morbidity and mortality in tropical countries were possibly due to better sunlight exposure that translates into adequate vitamin D status.
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