Displaying publications 81 - 100 of 533 in total

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  1. Abdullah J, Ahmad M, Heng LY, Karuppiah N, Sidek H
    Talanta, 2006 Oct 15;70(3):527-32.
    PMID: 18970803 DOI: 10.1016/j.talanta.2005.12.061
    The development of an optical biosensor based on immobilization of 3-methyl-2-benzothiazolinone hydrazone (MBTH) in hybrid nafion/sol-gel silicate film and tyrosinase in chitosan film for the detection of phenolic compounds has been described. Tyrosinase was immobilized in chitosan film deposited on the hybrid nafion/sol-gel silicate film containing MBTH. The enzymatic oxidation product of phenolic compounds were stabilized through formation of adduct with MBTH to produce a maroon color adduct. The color intensity of adduct was found to increase proportionally with the increase of the substrate concentrations after 5min exposure. The linearity of the biosensor towards phenol, catechol and m-cresol were in the respective concentration range of 0.5-7.0, 0.5-10.0 and 1.0-13.0mg/L with detection limit of 0.18, 0.23 and 0.43mg/L, respectively. The biosensor shows a good stability for at least 3 months.
  2. Wong FC, Ahmad M, Heng LY, Peng LB
    Talanta, 2006 Jun 15;69(4):888-93.
    PMID: 18970653 DOI: 10.1016/j.talanta.2005.11.034
    An optical biosensor consisting of a chromoionophore (ETH5294) (CM) doped sol-gel film interfaced with another sol-gel film immobilized with acetylcholinesterase (AChE) was employed to detect the insecticide dichlorvos. The main advantage of this optical biosensor is the use of a sol-gel layer with immobilized CM that possesses lipophilic property. The highly lipophilic nature of the CM and its compatibility with the sol-gel matrix has prevented leaching, which is frequently a problem in optical sensor construction based on pH indicator dyes. The immobilization of the indicator and enzyme was simple and need no chemical modification. The CM layer is pH sensitive and detects the pH changes of the acetylcholine chloride (AChCl) substrate when hydrolyzed by AChE layer deposited above. In the absence of the AChE layer, the pH response of the CM layer is linear from pH 6 to 8 (R(2)=0.98, n=3) and it showed no leaching of the lipophilic chromoionophore. When the AChE layer is deposited on top, the optical biosensor responds to AChCl with a linear dynamic range of 40-90mM AChCl (R(2)=0.984, n=6). The response time of the biosensor is 12min. Based on the optimum incubation time of 15min, a linear calibration curve of dichlorvos against the percentage inhibition of AChE was obtained from 0.5 to 7mg/L of dichlorvos (17-85% inhibition, R(2)=0.991, n=9). The detection limit for dichlorvos was 0.5mg/L. The results of the analysis of 1.7-6.0mg/L of dichlorvos using this optical biosensor agreed well with a gas chromatography-mass spectrometry detection method.
  3. Salmiati, Ujang Z, Salim MR, Md Din MF, Ahmad MA
    Water Sci Technol, 2007;56(8):179-85.
    PMID: 17978446
    This study aimed to produce polyhydroxyalkanoates (PHAs) from organic wastes by mixed bacterial cultures using anaerobic-aerobic fermentation systems. Palm oil mill effluent (POME) was used as an organic source, which was cultivated in a two-step-process of acidogenesis and acid polymerization. POME was operated in a continuous flow anaerobic reactor to access volatile fatty acids (VFAs) for PHAs production. During fermentation, VFA concentration was produced in the range of 5 to 8 g/L and the COD concentration reduced up to 80% from 65 g/L. The VFA from anaerobic fermentation was then utilised for PHA production using a mixed culture in availability of aerobic bioreactor. Production of PHAs was recorded high when using a high volume of substrates because of the higher VFA concentration. Even though the maximum PHA content was observed at only 40% of the cell dried weight (CDW), their production and performance are significant in mixed microbial culture.
  4. Abdullah J, Ahmad M, Heng LY, Karuppiah N, Sidek H
    Anal Bioanal Chem, 2006 Nov;386(5):1285-92.
    PMID: 17031625
    The stacked-film immobilization of 3-methyl-2-benzothiazolinone hydrazone (MBTH) in hybrid nafion/sol-gel silicate film and horseradish peroxidase (HRP) in chitosan, performed in order to allow the determination of phenolic compounds, was investigated via an optical method. The stacked films were deposited onto a microscope glass slide by a spin-coating technique. The quinone or free radical product formed by the enzymatic reactions of phenolic compounds interacts with MBTH to form azo-dye products, which can be measured spectrophotometrically at a wavelength of 500 nm. The color intensity of the product was found to increase in proportion to the phenolic concentration after 5 min of exposure. The response of the biosensor was linear over concentration ranges of 0.025-0.500, 0.010-0.070 and 0.050-0.300 mM for guaiacol, resorcinol and o-cresol, respectively, and gave detection limits of 0.010, 0.005 and 0.012 mM. The sensor exhibited good sensitivity and stability for at least two months.
  5. Bean LS, Heng LY, Yamin BM, Ahmad M
    Bioelectrochemistry, 2005 Feb;65(2):157-62.
    PMID: 15713567
    A single-step fabrication of a glucose biosensor with simultaneous immobilization of both ferrocene mediator and glucose oxidase in a photocurable methacrylic film consisting of poly(methyl methacrylate-co-2-hydroxylethyl methacrylate) was reported. The entrapped ferrocene showed reversible redox behaviour in the photocured film and no significant leaching of both entrapped ferrocene and enzyme glucose oxidase was observed because of the low water absorption properties of the co-polymer films. From electrochemical studies, ferrocene entrapped in the co-polymer film demonstrated slow diffusion properties. A linear glucose response range of 2-11 mM was obtained at low applied potential of +0.25 V. The glucose biosensor fabricated by this photocuring method yielded sensor reproducibility and repeatability with relative standard deviation of <10% and long-term stability of up to 14 days. The main advantage of the use of photocurable procedure is that biosensor membrane fabrication can be performed in a single step without any lengthy chemical immobilization of enzyme.
  6. Basri M, Samsudin S, Ahmad MB, Razak CN, Salleh AB
    Appl Biochem Biotechnol, 1999 Sep;81(3):205-17.
    PMID: 15304777
    Lipase from Candida rugosa was immobilized by entrapment on poly(N-vinyl- 2-pyrrolidone-co-2-hydroxyethyl methacrylate) (poly[VP-co-HEMA]) hydrogel, and divinylbenzene was the crosslinking agent. The immobilized enzymes were used in the esterification reaction of oleic acid and butanol in hexane. The activities of the immobilized enzymes and the leaching ability of the enzyme from the support with respect to the different compositions of the hydrogels were investigated. The thermal, solvent, and storage stability of the immobilized lipases was also determined. Increasing the percentage of composition of VP from 0 to 90, which corresponds to the increase in the hydrophilicity of the hydrogels, increased the activity of the immobilized enzyme. Lipase immobilized on VP(%):HEMA(%) 90:10 exhibited the highest activity. Lipase immobilized on VP(%):HEMA(%) 50:50 showed the highest thermal, solvent, storage, and operational stability compared to lipase immobilized on other compositions of hydrogels as well as the native lipase.
  7. Chong HL, Chia PS, Ahmad MN
    Bioresour Technol, 2013 Feb;130:181-6.
    PMID: 23306127 DOI: 10.1016/j.biortech.2012.11.136
    Oil palm shell, a waste from palm oil industry, was cleaned and utilized as adsorbent. Its particle size distribution gave the uniformity coefficient of approximately two indicating that it can be used as filter bed media for continuous operation without resting. Its measured pH(pzc) of 4.1 is below the common pH of constructed wetland water body suggesting positive adsorption for heavy metal. The effect of various parameters on its adsorption was studied via batch experiments. The adsorption of Cu(II) and Pb(II) ions by oil palm shell showed a slightly better fit with the Freundlich compared to Langmuir. Its monolayer adsorption capacities were found to be 1.756 and 3.390mg/g for Cu(II) and Pb(II), respectively. High correlation coefficient of over 0.99 given by the pseudo-second-order model suggests that the rate limiting factor may be chemisorption. These findings suggest its potential application as constructed wetland media for the removal of heavy metal.
  8. Ahmad M, Asghar A, Abdul Raman AA, Wan Daud WM
    PLoS One, 2015;10(10):e0141348.
    PMID: 26517827 DOI: 10.1371/journal.pone.0141348
    Fenton oxidation, an advanced oxidation process, is an efficient method for the treatment of recalcitrant wastewaters. Unfortunately, it utilizes H2O2 and iron-based homogeneous catalysts, which lead to the formation of high volumes of sludge and secondary pollutants. To overcome these problems, an alternate option is the usage of heterogeneous catalyst. In this study, a heterogeneous catalyst was developed to provide an alternative solution for homogeneous Fenton oxidation. Iron Zeolite Socony Mobile-5 (Fe-ZSM-5) was synthesized using a new two-step process. Next, the catalyst was characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, fourier transform infrared spectroscopy, and Brunauer-Emmett-Teller analysis and tested against a model wastewater containing the azo dye Acid Blue 113. Results showed that the loading of iron particles reduced the surface area of the catalyst from 293.59 to 243.93 m2/g; meanwhile, the average particle size of the loaded material was 12.29 nm. Furthermore, efficiency of the developed catalyst was evaluated by performing heterogeneous Fenton oxidation. Taguchi method was coupled with principal component analysis in order to assess and optimize mineralization efficiency. Experimental results showed that under optimized conditions, over 99.7% degradation and 77% mineralization was obtained, with a 90% reduction in the consumption of the developed catalyst. Furthermore, the developed catalyst was stable and reusable, with less than 2% leaching observed under optimized conditions. Thus, the present study proved that newly developed catalyst has enhanced the oxidation process and reduced the chemicals consumption.
  9. Widyawati T, Yusoff NA, Asmawi MZ, Ahmad M
    Nutrients, 2015 Sep;7(9):7764-80.
    PMID: 26389944 DOI: 10.3390/nu7095365
    Syzygium polyanthum (S. polyanthum), a plant belonging to Myrtaceae, is widely used in Indonesian and Malaysian cuisines. Diabetic patients in Indonesia also commonly use it as a traditional medicine. Hence, this study was conducted to investigate the antihyperglycemic effect of the methanol extract (ME) of S. polyanthum leaf and its possible mechanisms of action. To test for hypoglycemic activity, ME was administered orally to normal male Sprague Dawley rats after a 12-h fast. To further test for antihyperglycemic activity, the same treatment was administered to glucose-loaded (intraperitoneal glucose tolerance test, IPGTT) and streptozotocin (STZ)-induced diabetic rats, respectively. Hypoglycemic test in normal rats did not show significant reduction in blood glucose levels (BGLs) by the extract. Furthermore, IPGTT conducted on glucose-loaded normal rats also did not show significant reduction of BGLs. However, repeated administration of metformin and three doses of ME (250, 500 and 1000 mg/kg) for six days caused significant reduction of fasting BGLs in STZ-induced diabetic rats. The possible mechanisms of action of S. polyanthum antihyperglycemic activity were assessed by measurement of intestinal glucose absorption and glucose uptake by isolated rat abdominal muscle. It was found that the extract not only inhibited glucose absorption from the intestine but also significantly increased glucose uptake in muscle tissue. A preliminary phytochemical qualitative analysis of ME indicated the presence of tannins, glycosides, flavonoids, alkaloids and saponins. Additionally, Gas Chromatography-Mass Spectrometry (GC-MS) analysis detected squalene. In conclusion, S. polyanthum methanol leaf extract exerts its antihyperglycemic effect possibly by inhibiting glucose absorption from the intestine and promoting glucose uptake by the muscles.
  10. Ibrahim RW, Ahmad MZ, Al-Janaby HF
    Springerplus, 2016;5:375.
    PMID: 27066382 DOI: 10.1186/s40064-016-1996-9
    Recently, the generalized hypergeometric function is extended by utilizing the Beta function. Based on this type of function, we introduce a new operator in the open unit disk. The present article investigates some subordination and superordination results for certain normalized analytic functions in the open unit disk, which are acted upon by the generalized Noor integral operator. Some of outcomes improve and generalize previously known outcomes.
  11. Ibrahim RW, Ahmad MZ, Al-Janaby HF
    Saudi J Biol Sci, 2016 Jan;23(1):S45-9.
    PMID: 26858564 DOI: 10.1016/j.sjbs.2015.09.012
    A mutation is ultimately essential for adaptive evolution in all populations. It arises all the time, but is mostly fixed by enzymes. Further, most do consider that the evolution mechanism is by a natural assortment of variations in organisms in line for random variations in their DNA, and the suggestions for this are overwhelming. The altering of the construction of a gene, causing a different form that may be communicated to succeeding generations, produced by the modification of single base units in DNA, or the deletion, insertion, or rearrangement of larger units of chromosomes or genes. This altering is called a mutation. In this paper, a mathematical model is introduced to this reality. The model describes the time and space for the evolution. The tool is based on a complex domain for the space. We show that the evolution is distributed with the hypergeometric function. The Boundedness of the evolution is imposed by utilizing the Koebe function.
  12. Fong Yen W, Basri M, Ahmad M, Ismail M
    ScientificWorldJournal, 2015;2015:495271.
    PMID: 25853145 DOI: 10.1155/2015/495271
    Galantamine hydrobromide is formulated in tablets and capsules prescribed through oral delivery for the treatment of Alzheimer's disease. However, oral delivery of drugs can cause severe side effects such as nausea, vomiting, and gastrointestinal disturbance. Transdermal delivery of galantamine hydrobromide could avoid these unwanted side effects. In this work, galantamine hydrobromide was formulated in gel drug reservoir which was then fabricated in the transdermal patch. The in vitro drug release studies revealed that the drug release from the donor chamber to receptor chamber of Franz diffusion cell was affected by the amount of polymer, amount of neutralizer, amount of drug, types of permeation enhancer, and amount of permeation enhancer. Visual observations of the gels showed that all formulated gels are translucent, homogeneous, smooth, and stable. These gels have pH in the suitable range for skin. The gel also showed high drug content uniformity. Hence, this formulation can be further used in the preparation of transdermal patch drug delivery system.
  13. Ahmad M, Pitt Ford TR, Crum LA, Wilson RF
    Oral Surg. Oral Med. Oral Pathol., 1990 Sep;70(3):328-32.
    PMID: 2216361
    The physical mechanisms of ultrasound, namely cavitation and acoustic streaming, generated by the Enac-Osada ultrasonic unit were investigated for effectiveness in disrupting Streptococcus mitis. In addition, the bactericidal effect of ultrasound in the presence of 2.5% sodium hypochlorite was examined. Bacterial suspensions were irradiated directly with ultrasound in simulated root canals, and the viability of bacteria was examined after growth on a blood agar medium under anaerobic conditions at 37 degrees C for 5 days. The results indicated that ultrasound per se failed to disrupt bacteria but resulted in increases in the viable counts; the former was considered to be because of the lack of cavitation and the latter because of the dispersal effects of acoustic streaming. The 2.5% sodium hypochlorite solution demonstrated powerful bactericidal activity.
  14. Saad B, Kanapathy K, Ahmad MN, Hussin AH, Ismail Z
    Talanta, 1991 Dec;38(12):1399-402.
    PMID: 18965315
    Three main types of PVC solvent polymeric membrane ion-selective electrodes for chloroquine are described. They are based on three ion-pairing agents namely dipicrylamine (DPA), tetraphenylborate (TPB) or tetrakis(4-chlorophenyl)borate (TCPB) with either dioctylphenyl phosphonate (DOPP) or trioctyl phosphate (TOP) solvent mediator. All electrodes exhibit Nernstian responses, fast dynamic response times and a wide useful pH range. The best all-round electrode is based on TPB and TOP plasticizing solvent mediators with a limit of detection of 7.1 x 10(-6)M and was utilized for the assay of chloroquine in tablets. Direct potentiometric determinations with either the analyte addition method or the normal calibration method gave results comparable to the official method.
  15. Butt SZ, Ahmad M, Saeed H, Saleem Z, Javaid Z
    J Infect Public Health, 2019 06 10;12(6):854-860.
    PMID: 31196776 DOI: 10.1016/j.jiph.2019.05.015
    BACKGROUND: Guidelines assisted appropriate use of prophylactic antibiotics can lower the prevalence of surgical site infections (SSIs). The present study was conducted to evaluate the impact and cost-benefit value of pharmacist's educational intervention for antibiotic use in post-surgical prophylaxis.

    METHODS: A prospective quasi experimental study was conducted by enrolling 450 patients from tertiary care hospital of Lahore, Pakistan, 225 patients in each, control and intervention, arm using non-random convenient sampling. The study parameters included antibiotic indication, choice, dose, frequency, duration and associated costs. This study is registered with Chinese Clinical Trial Registry # ChiCTR-OON-17013246.

    RESULTS AND CONCLUSION: After educational intervention, in post-intervention arm, total compliance in terms of correct antibiotic choice, dose, frequency and duration increased from 1.3% to 12.4%. The rate of inappropriate antibiotic choice did not change significantly. After intervention only metronidazole utilization decreased (16%) significantly (p=0.011). Significant reductions were observed in mean duration of antibiotic prophylaxis (17%, p=0.003), average number of prescribed antibiotics (9.1%, p=0.014) and average antibiotic cost (25.7%, p=0.03), with reduction in mean hospitalization cost (p=0.003) and length of stay (p=0.023). Educational intervention was significantly associated (OR; 2.4, p=0.005) with appropriate antibiotic prophylaxis. The benefit of pharmacist intervention, mean antibiotic cost savings to mean cost of pharmacist time, was 4.8:1. Thus, the educational intervention resulted in significant reductions in the duration and average number of antibiotic use having considerable effect on therapy and hospitalization cost.

  16. Yam MF, Tan CS, Ahmad M, Shibao R
    Eur J Pharmacol, 2016 Oct 15;789:27-36.
    PMID: 27370961 DOI: 10.1016/j.ejphar.2016.06.047
    Previous studies demonstrated that eupatorin content in Orthosiphon stamineus fractions correlated with their vasorelaxation activity. Even with previous studies, there is still very little information on the vasorelaxation effect of eupatorin, and not many scientific studies had been carried out. Therefore, the present study was designed to investigate the vasorelaxation activity and mechanism of action of eupatorin. The vasorelaxation activity and the underlying mechanisms of eupatorin was evaluated on thoracic aortic rings isolated from Sprague Dawley rats. Eupatorin caused the relaxation of aortic rings pre-contracted with phenylephrine with and without endothelium (pD2=6.66±0.13, EMAX=99.72±6.39%; pD2=6.10±0.22, EMAX=65.78±8.01%), and also the relaxation of endothelium-intact aortic rings pre-contracted with potassium chloride (pD2=6.20±0.30, EMAX=71.89±12.25%). In the presence of Nω-nitro-l-arginine methyl ester (pD2<4.60, EMAX=24.91±6.39%), methylene blue (pD2=6.05±0.38, EMAX=66.79±9.69%), ODQ (pD25.84±0.32, EMAX=60.47±9.6%), indomethacin (pD2=6.27±0.21, EMAX=76.03±9.45%), tetraethylammonium (pD2=6.09±0.35, EMAX=69.35±11.31%), 4-aminopyridine (pD2=6.34±0.12, EMAX=76±6.1%), barium chloride (pD2=6.47±0.14, EMAX=79.61±10.02%), atropine (pD2=6.36±0.29, EMAX=86.47±12.95%) and propranolol (pD2=6.49±0.26, EMAX=83.2±12.01%), relaxation stimulated by eupatorin was significantly reduced. Eupatorin was also found to be active in reducing Ca(2+) release from sarcoplasmic reticulum and in blocking calcium channels. The present study demonstrates the vasorelaxation effect of eupatorin involving NO/sGC/cGMP and indomethacin pathways, calcium and potassium channels, and muscarinic and beta-adrenergic receptors.
  17. Sha'ari N, Manaf ZA, Ahmad M, Rahman FN
    Pediatr Int, 2017 Apr;59(4):408-415.
    PMID: 27805287 DOI: 10.1111/ped.13196
    BACKGROUND: Children with attention deficit-hyperactivity disorder (ADHD) may be at risk of nutrient deficiency due to the inability to sit through meals. This comparative cross-sectional study was therefore carried out to determine the nutritional status and feeding problems of ADHD children aged 4-12 years.

    METHODS: Sociodemographic data, anthropometric measurements and 3 day dietary intake record were collected from 54 ADHD children and 54 typical development (TD) children. The Behavioral Pediatrics Feeding Assessment Scale was used to assess feeding problems.

    RESULTS: Mean subject age was 8.6 ± 2.1 years. On anthropometric assessment, 11.1% of the ADHD children had wasting, while 1.9% had severe wasting. In contrast, none of the TD children had wasting. Approximately 5.6% of the ADHD children had stunting, as compared with 3.7% of the TD children, while none of the TD children had severe stunting compared with 3.7% of the ADHD children. More than half of the ADHD children had mid-upper arm circumference (MUAC) below the 5th percentile, indicating undernutrition, compared with only 35.2% of TD children. More than one-third of the ADHD children had feeding problems compared with 9.3% of TD children. There was a significant negative relationship between the ADHD children's feeding problems and bodyweight (r = -0338, P = 0.012), body mass index (r = -0322, P = 0.017) and MUAC (r = -0384, P = 0.004).

    CONCLUSION: Almost half of the ADHD children had suboptimal nutrition compared with 11.1% of the TD children. It is imperative to screen ADHD children for nutritional status and feeding problems to prevent negative health impacts later on.

  18. Anuar R, Mohd-Hisyamudin HP, Ahmad MH, Zulkiflee O
    Malays Orthop J, 2015 Nov;9(3):40-43.
    PMID: 28611908 MyJurnal DOI: 10.5704/MOJ.1511.006
    Delayed presentation of Developmental Dysplasia of Hip (DDH) comes with challenges in treatment as well as high surgical cost. Therefore the objective of this study is to quantify the economic impact of management of late presentation of DDH during a last 3-year period. We conducted a retrospective study with analysis of DDH cases managed between years 2012 to 2014. Early and late presentations of DDH were identified and cost management for both was estimated. Out of twenty-four DDH cases, thirteen cases fulfilled the inclusion criteria. All were female with majority of them presenting with unilateral DDH predominantly of the left hip. Most patients presented after age of six months and the principal complaint was abnormal or limping gait. The grand total cost for managing DDH during the three years period was USD 12,385.51, with 86% of the amount having been used to manage late presentation of DDH that was mostly contributed by the cost of surgery. We concluded that delayed presentation of DDH contributes heavily to high national expenditure. Early detection of DDH cases with systematic neonatal screening may help to minimize the incidence of the late presenting DDH and subsequently reduce the economic burden to the government.
  19. Nikmat AW, Ahmad M, Ng LO, Razali S
    ASEAN Journal of Psychiatry, 2008;9(2):65-72.
    MyJurnal
    Objective: To investigate the prevalence of parental stress and psychological wellbeing among parents with autistic children and their associations with dimensions of support system.
    Methods: This is a preliminary cross sectional study which randomly selected parents with clinically diagnosed autistic children. Those parents who attended psycho-education session on management of autistic children at Health Psychology Unit were randomly selected to enroll in the study. Psychological wellbeing, parental stress and dimensions of support system were assessed by using the General Health Questionnaire (GHQ-28), the Parenting Stress Index (PSI) and the Provision Social Relation (PSR), respectively.
    Results: Of 52 parents with autistic children (34 female and 18 male), about 90.4% of parents had significant parenting stress, and 53.8% of parents showed clinical disturbance in psychological wellbeing. Gender (t=1.67, p=0.02) and occupation (F=4.78, p=0.01) showed statistically significant association with psychological wellbeing. No association found between other socio-demographic factors, parental stress and psychological wellbeing with dimensions of support system among parents with autistic children.
    Conclusion: Parents with autistic children have high prevalence of stress and psychological disturbances. Interactions of various factors need to be acknowledged and considered in order to reduce the burden of parents with autistic children.
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