Displaying publications 21 - 40 of 87 in total

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  1. Expressed sequence tag-simple sequence repeats isolated from Shorea leprosula and their transferability to 36 species within the Dipterocarpaceae
    Ng KK, Lee SL, Tsumura Y, Ueno S, Ng CH, Lee CT
    Mol Ecol Resour, 2009 Jan;9(1):393-8.
    PMID: 21564660 DOI: 10.1111/j.1755-0998.2008.02238.x
    Simple sequence repeats (SSRs) derived from expressed sequence tags (ESTs) are valuable markers because they represent transcribed regions and often transferable to related taxa. Here, we report the development and characterization of EST-SSRs from Shorea leprosula. Fifty-four sequences containing SSRs were identified in 2003 unigenes assembled from 3159 ESTs. Twenty-four EST-SSRs were developed, of which four gave multiple amplifications, five were found to be monomorphic and 15 showed polymorphism, with allele numbers ranging from two to 17 in a single Pasoh Forest Reserve population of 24 individuals. The observed and expected heterozygosities ranged from 0.05 to 0.91 and from 0.16 to 0.93, respectively. Cross-species transferability of the 15 loci to 36 species within Dipterocarpaceae revealed between four and 14 loci that gave positive amplification and 10 loci were found to be transferable to more than 15 species.
  2. Synthesis, characterization, DNA-binding study and anticancer properties of ternary metal(II) complexes of edda and an intercalating ligand
    Ng CH, Kong KC, Von ST, Balraj P, Jensen P, Thirthagiri E, et al.
    Dalton Trans, 2008 Jan 28.
    PMID: 18185860 DOI: 10.1039/b709269e
    A series of ternary metal(ii) complexes {M(phen)(edda); 1a (Cu), 1b (Co), 1c (Zn), 1d (Ni); H(2)edda = N,N(')-ethylenediaminediacetic acid} of N,N'-ethylene-bridged diglycine and 1,10-phenanthroline were synthesized and characterized by elemental analysis, FTIR, UV-visible spectroscopy and magnetic susceptibility measurement. The interaction of these complexes with DNA was investigated using CD and EPR spectroscopy. MTT assay results of 1a-1c , screened on MCF-7 cancer cell lines, show that synergy between the metal and ligands results in significant enhancement of their antiproliferative properties. Preliminary results from apoptosis and cell cycle analyses with flow cytometry are reported. seems to be able to induce cell cycle arrest at G(0)/G(1). The crystal structure of 1a is also included.
  3. New crown-shaped polyoxovanadium(V) cluster cation with a mu(6)-sulfato anion and zwitterionic mu-(beta-alanine): crystal structure of [V(6)O(12)(OH)(3)(O(2)CCH(2)CH(2)NH(3))(3)(SO(4))][Na][SO(4)].13H(2)O
    Ng CH, Lim CW, Teoh SG, Fun HK, Usman A, Ng SW
    Inorg Chem, 2002 Jan 14;41(1):2-3.
    PMID: 11782136
    Treatment of vanadium(V) oxide with an ethanol-concentrated sulfuric acid mixture, followed by the addition of an equimolar amount of beta-alanine and sodium hydroxide, and finally raising the pH to 3.9 with sodium carbonate solution, under continuous heating in a water bath and in the presence of air, leads to the polyionic sodium cyclo-[mu(6)-(sulfato-O,O',O'')tris[mu-(beta-alanine-O,O')-mu-oxo]tris(mu-hydroxo-mu-oxo)hexa[oxovanadium(V)]] sulfate tridecahydrate which crystallizes in the monoclinic P2(1)/n space group [a = 9.5192(4), b = 20.1185(9), c = 22.6174(9) A, beta = 97.011(1) degrees; Z = 4]. The crown-shaped polyoxovanadium(V) cluster cation, with carboxylate-bridging amino acid ligands, has an Anderson structure with two unique capping sulfato ligands. Its structural analysis, together with IR, UV-vis, and preliminary data on its solution properties, is presented.
  4. Fulltext The APEC Digital Hub-WONCA Collaborative Framework on Integration of Mental Health into Primary Care in the Asia Pacific
    Dowrick C, Kassai R, Lam CLK, Lam RW, Manning G, Murphy J, et al.
    J Multidiscip Healthc, 2020;13:1693-1704.
    PMID: 33268991 DOI: 10.2147/JMDH.S271070
    Mental ill health affects individual well-being and national economic prosperity and makes up a substantial portion of the burden of disease globally, especially in the Asia-Pacific region. Integrating mental health into primary care is widely considered a key strategy to improve access to mental health care. Integration, however, is a complex process that needs to be addressed at multiple levels. A collaboration between the Asia-Pacific Economic Cooperation (APEC) Digital Hub for Mental Health and the World Organization of Family Doctors (WONCA) is described in this paper, which outlines a framework and next steps to improve the mental health of communities in APEC economies. This paper notes gaps related to the integration of mental health into primary care across the region and identifies enablers and current best practices from several APEC economies. The potential of digital technology to benefit primary mental health care for populations in the APEC region, including delivery of training programs for healthcare staff and access to resources for patients, is described. Finally, key next steps are proposed to promote enhanced integration into primary care and improve mental health care throughout the APEC region.
  5. Genetic Diversity and Demographic History of an Upper Hill Dipterocarp (Shorea platyclados): Implications for Conservation
    Ng CH, Lee SL, Tnah LH, Ng KKS, Lee CT, Diway B, et al.
    J Hered, 2019 12 17;110(7):844-856.
    PMID: 31554011 DOI: 10.1093/jhered/esz052
    Southeast Asian rainforests at upper hill elevations are increasingly vulnerable to degradation because most lowland forest areas have been converted to different land uses. As such, understanding the genetics of upper hill species is becoming more crucial for their future management and conservation. Shorea platyclados is an important, widespread upper hill dipterocarp in Malaysia. To elucidate the genetic structure of S. platyclados and ultimately provide guidelines for a conservation strategy for this species, we carried out a comprehensive study of the genetic diversity and demographic history of S. platyclados. Twenty-seven populations of S. platyclados across its range in Malaysia were genotyped at 15 polymorphic microsatellite loci and sequenced at seven noncoding chloroplast DNA (cpDNA) regions. A total of 303 alleles were derived from the microsatellite loci, and 29 haplotypes were identified based on 2892 bp of concatenated cpDNA sequences. The populations showed moderately high genetic diversity (mean HE = 0.680 for microsatellite gene diversity and HT = 0.650 for total haplotype diversity) and low genetic differentiation (FST = 0.060). Bayesian clustering divided the studied populations into two groups corresponding to western and eastern Malaysia. Bottleneck analysis did not detect any recent bottleneck events. Extended Bayesian skyline analyses showed a model of constant size for the past population history of this species. Based on our findings, priority areas for in situ and ex situ conservation and a minimum population size are recommended for the sustainable utilization of S. platyclados.
  6. A geographical traceability system for Merbau (Intsia palembanica Miq.), an important timber species from peninsular Malaysia
    Ng CH, Ng KKS, Lee SL, Tnah LH, Lee CT, Zakaria NF
    Forensic Sci Int Genet, 2020 01;44:102188.
    PMID: 31648150 DOI: 10.1016/j.fsigen.2019.102188
    To inform product users about the origin of timber, the implementation of a traceability system is necessary for the forestry industry. In this study, we developed a comprehensive genetic database for the important tropical timber species Merbau, Intsia palembanica, to trace its geographic origin within peninsular Malaysia. A total of 1373 individual trees representing 39 geographically distinct populations of I. palembanica were sampled throughout peninsular Malaysia. We analyzed the samples using a combination of four chloroplast DNA (cpDNA) markers and 14 short tandem repeat (STR) markers to establish both cpDNA haplotype and STR allele frequency databases. A haplotype map was generated through cpDNA sequencing for population identification, resulting in six unique haplotypes based on 10 informative intraspecifically variable sites. Subsequently, an STR allele frequency database was developed from 14 STRs allowing individual identification. Bayesian cluster analysis divided the individuals into two genetic clusters corresponding to the northern and southern regions of peninsular Malaysia. Tests of conservativeness showed that the databases were conservative after the adjustment of the θ values to 0.2000 and 0.2900 for the northern (f = 0.0163) and southern (f = 0.0285) regions, respectively. Using self-assignment tests, we observed that individuals were correctly assigned to populations at rates of 40.54-94.12% and to the identified regions at rates of 79.80-80.62%. Both the cpDNA and STR markers appear to be useful for tracking Merbau timber originating from peninsular Malaysia. The use of these forensic tools in addition to the existing paper-based timber tracking system will help to verify the legality of the origin of I. palembanica and to combat illegal logging issues associated with the species.
  7. Mating system and seed variation of Acacia hybrid (A. mangium x A. auriculiformis)
    Ng CH, Lee SL, Ng KK, Muhammad N, Ratnam W
    J Genet, 2009 Apr;88(1):25-31.
    PMID: 19417541
    The mating system and seed variation of Acacia hybrid (A. mangium x A. auriculiformis) were studied using allozymes and random amplified polymorphic DNA (RAPD) markers, respectively. Multi-locus outcrossing rate estimations indicated that the hybrid was predominantly outcrossed (mean+/- s.e. t(m) = 0.86+/-0.01). Seed variation was investigated using 35 polymorphic RAPD fragments. An analysis of molecular variance (AMOVA) revealed the highest genetic variation among seeds within a pod (66%-70%), followed by among pods within inflorescence (29%-37%), and the least variation among inflorescences within tree (1%). In addition, two to four RAPD profiles could be detected among seeds within pod. Therefore, the results suggest that a maximum of four seeds per pod could be sampled for the establishment of a mapping population for further studies.
  8. Enantiomeric pair of copper(II) polypyridyl-alanine complexes: Effect of chirality on their interaction with biomolecules
    Ng CH, Chan CW, Lai JW, Ooi IH, Chong KV, Maah MJ, et al.
    J Inorg Biochem, 2016 07;160:1-11.
    PMID: 27105312 DOI: 10.1016/j.jinorgbio.2016.04.003
    Like chiral organic drugs, the chemical and biological properties of metal complexes can be dependent on chirality. Two pairs of [Cu(phen)(ala)(H2O)]X·xH2O (phen=1.10-phenanthroline: X=NO3(-); ala: l-alanine (l-ala), 1 and d-alanine (d-ala) 2; and (X=Cl(-); ala: l-ala, 3 and d-ala, 4) complex salts (x=number of lattice water molecules) have been synthesized and characterized. The crystal structure of 3 has been determined. The same pair of enantiomeric species, viz. [Cu(phen)(l-ala)(H2O)](+) and [Cu(phen)(d-ala)(H2O)](+), have been identified to be present in the aqueous solutions of both 1 and 3, and in those of both 2 and 4 respectively. Both 3 and 4 bind more strongly to ds(AT)6 than ds(CG)6. There is no or insignificant effect of the chirality of 3 and 4 on the production of hydroxyl radicals, binding to deoxyribonucleic acid from calf thymus (CT-DNA), ds(CG)6, G-quadruplex and 17-base pair duplex, and inhibition of both topoisomerase I and proteasome. Among the three proteasome proteolytic sites, the trypsin-like site is inhibited most strongly by these complexes. However, the chirality of 3 and 4 does affect the number of restriction enzymes inhibited, and their binding constants towards ds(AT)6 and serum albumin.
  9. DNA molecular recognition and cellular selectivity of anticancer metal(II) complexes of ethylenediaminediacetate and phenanthroline: multiple targets
    Von ST, Seng HL, Lee HB, Ng SW, Kitamura Y, Chikira M, et al.
    J Biol Inorg Chem, 2012 Jan;17(1):57-69.
    PMID: 21833656 DOI: 10.1007/s00775-011-0829-0
    By inhibiting only two or three of 12 restriction enzymes, the series of [M(phen)(edda)] complexes [M(II) is Cu, Co, Zn; phen is 1,10-phenanthroline; edda is N,N'-ethylenediaminediacetate] exhibit DNA binding specificity. The Cu(II) and Zn(II) complexes could differentiate the palindromic sequences 5'-CATATG-3' and 5'-GTATAC-3', whereas the Co(II) analogue could not. This and other differences in their biological properties may arise from distinct differences in their octahedral structures. The complexes could inhibit topoisomerase I, stabilize or destabilize G-quadruplex, and lower the mitochondrial membrane potential of MCF7 breast cells. The pronounced stabilization of G-quadruplex by the Zn(II) complex may account for the additional ability of only the Zn(II) complex to induce cell cycle arrest in S phase. On the basis of the known action of anticancer compounds against the above-mentioned individual targets, we suggest the mode of action of the present complexes could involve multiple targets. Cytotoxicity studies with MCF10A and cisplatin-resistant MCF7 suggest that these complexes exhibit selectivity towards breast cancer cells over normal ones.
  10. Mechanisms of action of Panax notoginseng ethanolic extract for its vasodilatory effects and partial characterization of vasoactive compounds
    Loh YC, Tan CS, Ch'ng YS, Ng CH, Yeap ZQ, Yam MF
    Hypertens Res, 2019 02;42(2):182-194.
    PMID: 30464217 DOI: 10.1038/s41440-018-0139-9
    Panax notoginseng is the most valuable medicinal plant and has been used clinically for more than two thousand years to treat various diseases, including hypertension. Previous studies claimed that different isolated compounds from P. notoginseng are involved in different pathways for vasodilation. It is strongly believed that these vasodilating compounds might act synergistically in contributing vasodilatory effects via holistic signaling pathways. The present study aims to evaluate the vasodilatory effect and mechanism of action employed by the crude extract of P. notoginseng. The fingerprint of P. notoginseng was developed using tri-step FTIR and HPTLC. The contents of Rg1 and Rb1 in the active extract (PN95) were further quantified via HPTLC. The vasodilatory effect of PN95 was evaluated using an in vitro aortic ring model. The results showed that PN95 contains a high amount of Rg1 and Rb1, 25.9 and 13.6%, respectively. The vasodilatory effect of PN95 was elicited via the NO/sGC/cGMP and β2-adrenergic receptors pathways. Furthermore, PN95 could manage vascular tone by regulating action potentials via potassium and both VOCC and IP3R pathways. The results obtained fulfilled the expected outcome where the PN95 employed more signaling pathways than any of the single active compounds; hence, the holistic therapeutic effect could be achieved and would more easily translate to applications for the treatment of human diseases.
  11. Barrier protective effects of 2,4,6-trihydroxy-3-geranyl acetophenone on lipopolysaccharides-stimulated inflammatory responses in human umbilical vein endothelial cells
    Chong YJ, Musa NF, Ng CH, Shaari K, Israf DA, Tham CL
    J Ethnopharmacol, 2016 Nov 04;192:248-255.
    PMID: 27404229 DOI: 10.1016/j.jep.2016.07.032
    PHARMOCOLOGICAL RELEVANCE: 2,4,6-trihydroxy-3-geranyl acetophenone (tHGA), is a phloroglucinol compound found naturally in Melicope ptelefolia. Melicope ptelefolia has been used traditionally for centuries as natural remedy for wound infections and inflammatory diseases.

    AIM OF THE STUDY: Endothelial barrier dysfunction is a pathological hallmark of many diseases and can be caused by lipopolysaccharides (LPS) stimulation. Therefore, this study aims to investigate the possible barrier protective effects of tHGA upon LPS-stimulated inflammatory responses in human umbilical vein endothelial cells (HUVECs).

    MATERIALS AND METHODS: HUVECs were pretreated with tHGA prior to LPS stimulation, where inflammatory parameters including permeability, monocyte adhesion and migration, and release of pro-inflammatory mediators were examined. Additionally, the effect of tHGA on F-actin rearrangement and adhesion protein expression of LPS-stimulated HUVECs was evaluated.

    RESULTS: It was found that pretreatment with tHGA inhibited monocyte adhesion and transendothelial migration, reduced endothelial hyperpermeability and secretion of prostaglandin E2 (PGE2). Additionally, tHGA inhibited cytoskeletal rearrangement and adhesion protein expression on LPS-stimulated HUVECs.

    CONCLUSION: As the regulation of endothelial barrier dysfunction can be one of the therapeutic strategies to improve the outcome of inflammation, tHGA may be able to preserve vascular barrier integrity of endothelial cells following LPS-stimulated dysfunction, thereby endorsing its potential usefulness in vascular inflammatory diseases.

  12. Fulltext Geographic origin and individual assignment of Shorea platyclados (Dipterocarpaceae) for forensic identification
    Ng CH, Lee SL, Tnah LH, Ng KKS, Lee CT, Diway B, et al.
    PLoS One, 2017;12(4):e0176158.
    PMID: 28430826 DOI: 10.1371/journal.pone.0176158
    The development of timber tracking methods based on genetic markers can provide scientific evidence to verify the origin of timber products and fulfill the growing requirement for sustainable forestry practices. In this study, the origin of an important Dark Red Meranti wood, Shorea platyclados, was studied by using the combination of seven chloroplast DNA and 15 short tandem repeats (STRs) markers. A total of 27 natural populations of S. platyclados were sampled throughout Malaysia to establish population level and individual level identification databases. A haplotype map was generated from chloroplast DNA sequencing for population identification, resulting in 29 multilocus haplotypes, based on 39 informative intraspecific variable sites. Subsequently, a DNA profiling database was developed from 15 STRs allowing for individual identification in Malaysia. Cluster analysis divided the 27 populations into two genetic clusters, corresponding to the region of Eastern and Western Malaysia. The conservativeness tests showed that the Malaysia database is conservative after removal of bias from population subdivision and sampling effects. Independent self-assignment tests correctly assigned individuals to the database in an overall 60.60-94.95% of cases for identified populations, and in 98.99-99.23% of cases for identified regions. Both the chloroplast DNA database and the STRs appear to be useful for tracking timber originating in Malaysia. Hence, this DNA-based method could serve as an effective addition tool to the existing forensic timber identification system for ensuring the sustainably management of this species into the future.
  13. Rapid authentication and identification of different types of A. roxburghii by Tri-step FT-IR spectroscopy
    Chen Y, Huang J, Yeap ZQ, Zhang X, Wu S, Ng CH, et al.
    Spectrochim Acta A Mol Biomol Spectrosc, 2018 Jun 15;199:271-282.
    PMID: 29626818 DOI: 10.1016/j.saa.2018.03.061
    Anoectochilus roxburghii (Wall.) Lindl. (Orchidaceae) is a precious traditional Chinese medicinal herb and has been perennially used to treat various illness. However, there were unethical sellers who adulterated wild A. roxburghii with tissue cultured and cultivated ones. Therefore, there is an urgent need for an effective authentication method to differentiate between these different types of A. roxburghii. In this research, the infrared spectroscopic tri-step identification approach including Fourier transform infrared spectroscopy (FT-IR), Second derivative infrared spectra (SD-IR) and two-dimensional correlation infrared spectra (2D-IR) was used to develop a simple and rapid method to discriminate between wild, cultivated and tissue cultivated A. roxburghii plant. Through this study, all three types of A. roxburghii plant were successfully identified and discriminated through the infrared spectroscopic tri-step identification method. Besides that, all the samples of wild, cultivated and tissue cultivated A. roxburghii plant were analysed with the Soft Independent Modelling of Class Analogy (SIMCA) pattern recognition technique to test and verify the experimental results. The results showed that the three types of A. roxburghii can be discriminated clearly as the recognition rate was 100% for all three types and the rejection rate was more than 60%. 70% of the validated samples were also identified correctly by the SIMCA model. The SIMCA model was also validated by comparing 70 standard herbs to the model. As a result, it was demonstrated that the macroscopic IR fingerprint method and the classification analysis could discriminate not only between the A. roxburghi samples and the standard herbs, it could also distinguish between the three different types of A. roxburghi plant in a direct, rapid and holistic manner.
  14. Fulltext Hits-to-Lead Optimization of the Natural Compound 2,4,6-Trihydroxy-3-geranyl-acetophenone (tHGA) as a Potent LOX Inhibitor: Synthesis, Structure-Activity Relationship (SAR) Study, and Computational Assignment
    Ng CH, Rullah K, Abas F, Lam KW, Ismail IS, Jamaludin F, et al.
    Molecules, 2018 Sep 30;23(10).
    PMID: 30274341 DOI: 10.3390/molecules23102509
    A new series of 2,4,6-trihydroxy-3-geranyl-acetophenone (tHGA) analogues were synthesized and evaluated for their lipoxygenase (LOX) inhibitory activity. Prenylated analogues 4a⁻g (half maximal inhibitory concentration (IC50) values ranging from 35 μ M to 95 μ M) did not exhibit better inhibitory activity than tHGA (3a) (IC50 value: 23.6 μ M) due to the reduction in hydrophobic interaction when the alkyl chain length was reduced. One geranylated analogue, 3d, with an IC50 value of 15.3 μ M, exhibited better LOX inhibitory activity when compared to tHGA (3a), which was in agreement with our previous findings. Kinetics study showed that the most active analogue (3e) and tHGA (3a) acted as competitive inhibitors. The combination of in silico approaches of molecular docking and molecular dynamic simulation revealed that the lipophilic nature of these analogues further enhanced the LOX inhibitory activity. Based on absorption, distribution, metabolism, excretion, and toxicity (ADMET) and toxicity prediction by komputer assisted technology (TOPKAT) analyses, all geranylated analogues (3a⁻g) showed no hepatotoxicity effect and were biodegradable, which indicated that they could be potentially safe drugs for treating inflammation.
  15. Fulltext Estimating the utility value of hypoglycaemia according to severity and frequency using the visual analogue scale (VAS) and time trade-off (TTO) survey
    Shafie AA, Ng CH, Thanimalai S, Haron N, Manocha AB
    J Diabetes Metab Disord, 2018 Dec;17(2):269-275.
    PMID: 30918862 DOI: 10.1007/s40200-018-0369-z
    Objectives: The primary objective of this study was to estimate the health utility values for hypoglycaemia events according to their severity and frequency. The secondary objective was to compare the health utilities between those with Type 2 Diabetes Mellitus and the general population.

    Method: The health utilities of hypoglycaemia event were measured using Visual Analogue Scale (VAS) and Time Trade-Off (TTO) methods among conveniently sampled consenting adults (>18 years and literate in either English or Malay language), which were then divided into two groups: those in the general population (GP) and those with Type 2 Diabetes Mellitus (T2DM). Each respondent was required to value 13 different health states, including frequencies of daytime hypoglycaemia and nocturnal hypoglycaemia, each depending on its severity (non-severe or severe).

    Results: 256 respondents from the GP and 99 respondents with T2DM completed the survey. The T2DM group gave higher VAS-values compared to the GP group. The highest mean VAS-utility value for non-severe nocturnal hypoglycaemia occurring once monthly was 0.543 (SD 0.161), and for severe daytime hypoglycaemia occurring once quarterly was 0.293 (SD 0.162) which was the lowest utility value compared to other health states. However, non-severe nocturnal hypoglycaemia occurring once quarterly was 0.537 (SD 0.284) and has the highest TTO-utility value. Severe nocturnal hypoglycaemia occurring once quarterly has the lowest utility value which was -0.104 (SD 0.380). Daytime hypoglycaemia has lower utility value compared to nocturnal hypoglycaemia. Severe hypoglycaemia has a greater disutility compared with the non-severe hypoglycaemia in both studied groups.

    Conclusion: The findings show that as a health utility, hypoglycaemia has a substantial impact on utility with severe hypoglycaemia having a greater negative impact compared to non-severe events across the board. This highlights the importance of preventing development of severe hypoglycaemia in patients with Type 2 Diabetes Mellitus at any time of the day.

  16. Overview of Signaling Mechanism Pathways Employed by BPAid in Vasodilatory Activity
    Loh YC, Tan CS, Ch'ng YS, Ahmad M, Ng CH, Yam MF
    J Med Food, 2017 Dec;20(12):1201-1213.
    PMID: 28953423 DOI: 10.1089/jmf.2017.3958
    Hypertension, one of the famous "silent killers" that can attack people at any age, is a current hot topic among scientists due to multiple syndromic behavior and concomitant diseases. The new scientific-based Traditional Chinese Medicine (TCM) formulation approach was used in a previous study by combining five TCM herbs, including Gastrodia elata Bl., Uncaria rhynchophylla (Miq.) Miq. ex Havil., Pueraria thomsonii Benth., Panax notoginseng (Burk.) F.H. Chen, and Alisma orientalis (Sam.) Juzep in optimized ratio (named BPAid). The objective of the present study was to evaluate the mechanism pathways employed by BPAid for vasodilatory effect with the use of an in vitro isolated aortic rings assay. Interestingly, all the mechanisms investigated were involved in the BPAid's vasodilation activity in which the majority contributed through the nitric oxide/soluble guanylyl cyclase/cyclic guanosine monophosphate (NO/sGC/cGMP) pathways, followed by prostacyclin (PGI2), β2-adrenergic, and M3-receptors pathways. Furthermore, the BPAid appeared to manage vascular tone by regulating action potential through potassium and both voltage-operated calcium channel and inositol triphosphate receptor (IP3R) pathways. The results obtained has confirmed the expected outcome that the benefits of TCM herbs in BPAid can meet the criteria of counteracting multiple signaling mechanism pathways involved in the etiology of hypertension. In addition to this study, the fingerprints and chemical properties of BPAid was identified by using tri-step Fourier transform infrared spectroscopy and compared with its derivatives. The results obtained suggested that the majority of the vasodilatory effects exerted by BPAid were attributed to the presence of saponins and aromatic ring-containing vasoactive compounds.
  17. Anti-hypertensive and vasodilatory effects of amended Banxia Baizhu Tianma Tang
    Tan CS, Loh YC, Ng CH, Ch'ng YS, Asmawi MZ, Ahmad M, et al.
    Biomed Pharmacother, 2018 Jan;97:985-994.
    PMID: 29136777 DOI: 10.1016/j.biopha.2017.11.021
    Although Banxia Baizhu Tianma Tang (BBT) has been long administered for hypertensive treatment in Traditional Chinese Medicine (TCM), the ratio of the herbal components that makes up the formulation has not been optimized with respect to the anti-hypertensive effect that it inherently possesses. A newly amended BBT (ABBT) formulation was developed using the evidence-based approach of orthogonal stimulus-response compatibility model. The ABBT showed enhanced therapeutic effect while maintaining its traditional theoretical approach rooted in TCM. This study was designed to investigate the possible mechanism of actions involved in the vasodilatory activity of ABBT-50 by evaluating its vasodilative effect on isolated Sprague Dawley rats in the presence of absence of various antagonists. When pre-contracted with phenylephrine, relaxation was observed in endothelium intact (EC50=0.027±0.003mg/ml, Rmax=109.8±2.12%) and denuded aortic rings (EC50=0.409±0.073mg/ml, Rmax=63.15±1.78%), as well as in endothelium intact aortic rings pre-contracted with potassium chloride (EC50=32.7±12.16mg/ml, Rmax=34.02±3.82%). Significant decrease in the vasodilative effect of ABBT-50 was observed in the presence of Nω-nitro-l-arginine methyl ester (EC50=0.12±0.021mg/ml, Rmax=75.33±3.28%), 1H-[1,2,4] Oxadiazolo[4,3-a]quinoxalin-1-one (EC50=0.463±0.18mg/ml, Rmax=54.48±2.02%), methylene blue (EC50=0.19±0.037mg/ml, Rmax=83.69±3.19%), indomethacin (EC50=0.313±0.046mg/ml, Rmax=71.33±4.12%), atropine (EC50=0.146±0.013mg/ml, Rmax=77.2±3.41%), and 4-aminopyridine (EC50=0.045±0.008mg/ml, Rmax=95.55±2.36%). ABBT-50 was also suppressing Ca2+ release from sarcoplasmic reticulum and inhibiting calcium channels. Vasodilatory effects of ABBT-50 are mediated through NO/sGC/cGMP cascade and PGI2, followed by muscarinic pathways and calcium channels.
  18. Fulltext Tunable Open Circuit Voltage by Engineering Inorganic Cesium Lead Bromide/Iodide Perovskite Solar Cells
    Ng CH, Ripolles TS, Hamada K, Teo SH, Lim HN, Bisquert J, et al.
    Sci Rep, 2018 02 06;8(1):2482.
    PMID: 29410450 DOI: 10.1038/s41598-018-20228-0
    Perovskite solar cells based on series of inorganic cesium lead bromide and iodide mixture, CsPbBr3-xI x , where x varies between 0, 0.1, 0.2, and 0.3 molar ratio were synthesized by two step-sequential deposition at ambient condition to design the variations of wide band gap light absorbers. A device with high overall photoconversion efficiency of 3.98 % was obtained when small amount of iodide (CsPbBr2.9I0.1) was used as the perovskite and spiro-OMeTAD as the hole transport material (HTM). We investigated the origin of variation in open circuit voltage, Voc which was shown to be mainly dependent on two factors, which are the band gap of the perovskite and the work function of the HTM. An increment in Voc was observed for the device with larger perovskite band gap, while keeping the electron and hole extraction contacts the same. Besides, the usage of bilayer P3HT/MoO3 with deeper HOMO level as HTM instead of spiro-OMeTAD, thus increased the Voc from 1.16 V to 1.3 V for CsPbBr3 solar cell, although the photocurrent is lowered due to charge extraction issues. The stability studies confirmed that the addition of small amount of iodide into the CsPbBr3 is necessarily to stabilize the cell performance over time.
  19. Fulltext Overview of the Microenvironment of Vasculature in Vascular Tone Regulation
    Loh YC, Tan CS, Ch'ng YS, Yeap ZQ, Ng CH, Yam MF
    Int J Mol Sci, 2018 Jan 02;19(1).
    PMID: 29301280 DOI: 10.3390/ijms19010120
    Hypertension is asymptomatic and a well-known "silent killer", which can cause various concomitant diseases in human population after years of adherence. Although there are varieties of synthetic antihypertensive drugs available in current market, their relatively low efficacies and major application in only single drug therapy, as well as the undesired chronic adverse effects associated, has drawn the attention of worldwide scientists. According to the trend of antihypertensive drug evolution, the antihypertensive drugs used as primary treatment often change from time-to-time with the purpose of achieving the targeted blood pressure range. One of the major concerns that need to be accounted for here is that the signaling mechanism pathways involved in the vasculature during the vascular tone regulation should be clearly understood during the pharmacological research of antihypertensive drugs, either in vitro or in vivo. There are plenty of articles that discussed the signaling mechanism pathways mediated in vascular tone in isolated fragments instead of a whole comprehensive image. Therefore, the present review aims to summarize previous published vasculature-related studies and provide an overall depiction of each pathway including endothelium-derived relaxing factors, G-protein-coupled, enzyme-linked, and channel-linked receptors that occurred in the microenvironment of vasculature with a full schematic diagram on the ways their signals interact. Furthermore, the crucial vasodilative receptors that should be included in the mechanisms of actions study on vasodilatory effects of test compounds were suggested in the present review as well.
  20. Anti-allergic activity of 2,4,6-trihydroxy-3-geranylacetophenone (tHGA) via attenuation of IgE-mediated mast cell activation and inhibition of passive systemic anaphylaxis
    Tan JW, Israf DA, Harith HH, Md Hashim NF, Ng CH, Shaari K, et al.
    Toxicol Appl Pharmacol, 2017 03 15;319:47-58.
    PMID: 28167223 DOI: 10.1016/j.taap.2017.02.002
    tHGA, a geranyl acetophenone compound originally isolated from a local shrub called Melicope ptelefolia, has been previously reported to prevent ovalbumin-induced allergic airway inflammation in a murine model of allergic asthma by targeting cysteinyl leukotriene synthesis. Mast cells are immune effector cells involved in the pathogenesis of allergic diseases including asthma by releasing cysteinyl leukotrienes. The anti-asthmatic properties of tHGA could be attributed to its inhibitory effect on mast cell degranulation. As mast cell degranulation is an important event in allergic responses, this study aimed to investigate the anti-allergic effects of tHGA in cellular and animal models of IgE-mediated mast cell degranulation. For in vitro model of IgE-mediated mast cell degranulation, DNP-IgE-sensitized RBL-2H3 cells were pre-treated with tHGA before challenged with DNP-BSA to induce degranulation. For IgE-mediated passive systemic anaphylaxis, Sprague Dawley rats were sensitized by intraperitoneal injection of DNP-IgE before challenged with DNP-BSA. Both in vitro and in vivo models showed that tHGA significantly inhibited the release of preformed mediators (β-hexosaminidase and histamine) as well as de novo mediators (interleukin-4, tumour necrosis factor-α, prostaglandin D2 and leukotriene C4). Pre-treatment of tHGA also prevented IgE-challenged RBL-2H3 cells and peritoneal mast cells from undergoing morphological changes associated with mast cell degranulation. These findings indicate that tHGA possesses potent anti-allergic activity via attenuation of IgE-mediated mast cell degranulation and inhibition of IgE-mediated passive systemic anaphylaxis. Thus, tHGA may have the potential to be developed as a mast cell stabilizer for the treatment of allergic diseases in the future.
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