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Enzymatic synthesis of farnesyl laurate in organic solvent: initial water activity, kinetics mechanism, optimization of continuous operation using packed bed reactor and mass transfer studies

Rahman NK, Kamaruddin AH, Uzir MH

Bioprocess Biosyst Eng, 2011 Aug;34(6):687-99.
PMID: 21327986 DOI: 10.1007/s00449-011-0518-y

The influence of water activity and water content was investigated with farnesyl laurate synthesis catalyzed by Lipozyme RM IM. Lipozyme RM IM activity depended strongly on initial water activity value. The best results were achieved for a reaction medium with an initial water activity of 0.11 since it gives the best conversion value of 96.80%. The rate constants obtained in the kinetics study using Ping-Pong-Bi-Bi and Ordered-Bi-Bi mechanisms with dead-end complex inhibition of lauric acid were compared. The corresponding parameters were found to obey the Ordered-Bi-Bi mechanism with dead-end complex inhibition of lauric acid. Kinetic parameters were calculated based on this model as follows: V (max) = 5.80 mmol l(-1) min(-1) g enzyme(-1), K (m,A) = 0.70 mmol l(-1) g enzyme(-1), K (m,B) = 115.48 mmol l(-1) g enzyme(-1), K (i) = 11.25 mmol l(-1) g enzyme(-1). The optimum conditions for the esterification of farnesol with lauric acid in a continuous packed bed reactor were found as the following: 18.18 cm packed bed height and 0.9 ml/min substrate flow rate. The optimum molar conversion of lauric acid to farnesyl laurate was 98.07 ± 0.82%. The effect of mass transfer in the packed bed reactor has also been studied using two models for cases of reaction limited and mass transfer limited. A very good agreement between the mass transfer limited model and the experimental data obtained indicating that the esterification in a packed bed reactor was mass transfer limited.
Studies of reaction parameters on synthesis of Citronellyl laurate ester via immobilized Candida rugosa lipase in organic media

Serri NA, Kamaruddin AH, Long WS

Bioprocess Biosyst Eng, 2006 Oct;29(4):253-60.
PMID: 16868763

Immobilized Candida rugosa lipase was used for the synthesis of citronellyl laurate from citronellol and lauric acid. Screening of different types of support (Amberlite MB-1 and Celite) for immobilization of lipase and solvent (n-hexane, n-heptane, and iso-octane) and optimization of reaction conditions, such as catalyst loading, effect of substrates molar ratio and temperature, have been studied. The maximum enzyme activity was obtained at 310 K. The immobilized C. rugosa lipase onto Amberlite MB-1 support was found to be the best support with a conversion of 89% of citronellyl laurate ester in iso-octane compared to Celite 545. Deactivation of C. rugosa lipase at 313, 318 and 323 K were observed. Ordered bi bi mechanism with dead end complex of lauric acid was found to fit the initial rate data and the kinetic parameters were obtained by non-linear regression analysis.
Dynamic kinetic resolution: alternative approach in optimizing S-ibuprofen production

Fazlena H, Kamaruddin AH, Zulkali MM

Bioprocess Biosyst Eng, 2006 Mar;28(4):227-33.
PMID: 16215728

A lipase catalysed enantioselective hydrolysis process under in situ racemization of the remaining (R)-ibuprofen ester substrate with sodium hydroxide as the catalyst was developed for the production of S-ibuprofen from (R,S)-ibuprofen ester in isooctane. Detailed investigations on parameters study indicated that 0.5 M NaOH, addition of 20% (v/v) co-solvent (dimethyl sulphoxide), operating temperature of 45 degrees C, and 40 mmol/L substrate gave 86% conversion and 99.4% optical purity of S-ibuprofen in dynamic kinetic resolution. Meanwhile, in common enzymatic kinetic resolution process, only 42% conversion of the racemate and 93% enantiomeric excess of the product was obtained which are of lower values as compared to dynamic kinetic resolution. The S-ibuprofen produced during each process was evaluated and approximately 50% increment in concentration of S-acid product was produced when dynamic kinetic resolution was applied into the process.
Kinetics study of palm oil hydrolysis using immobilized lipase Candida rugosa in packed bed reactor

Min CS, Bhatia S, Kamaruddin AH

Artif Cells Blood Substit Immobil Biotechnol, 1999 Sep-Nov;27(5-6):417-21.
PMID: 10595442

Continuous hydrolysis of palm oil triglyceride in organic solvent using immobilized Candida rugosa on the Amberlite MB-1 as a source of immobilized lipase was studied in packed bed reactor. The enzymatic kinetics of hydrolysis reaction was studied by changing the substrate concentration, reaction temperature and residence time(tau) in the reactor. At 55 degrees C, the optimum water concentration was found to be 15 % weight per volume of solution (%w/v). The Michaelis-Menten kinetic model was used to obtain the reaction parameters, Km(app) and V max(app). The activation energies were found to be quite low indicating that the lipase-catalyzed process is controlled by diffusion of substrates. The Michaelis-Menten kinetic model was found to be suitable at low water concentration 10-15 %w/v of solution. At higher water concentration, substrate inhibition model was used for data analysis. Reactor operation was found to play an important role in the palm oil hydrolysis kinetic.
Modeling and simulation of an enzymatic reactor for hydrolysis of palm oil

Bhatia S, Naidu AD, Kamaruddin AH

Artif Cells Blood Substit Immobil Biotechnol, 1999 Sep-Nov;27(5-6):435-40.
PMID: 10595445

Hydrolysis of palm oil has become an important process in Oleochemical industries. Therefore, an investigation was carried out for hydrolysis of palm oil to fatty acid and glycerol using immobilized lipase in packed bed reactor. The conversion vs. residence time data were used in Michaelis-Menten rate equation to evaluate the kinetic parameters. A mathematical model for the rate of palm oil hydrolysis was proposed incorporating role of external mass transfer and pore diffusion. The model was simulated for steady-state isothermal operation of immobilized lipase packed bed reactor. The experimental data were compared with the simulated results. External mass transfer was found to affect the rate of palm oil hydrolysis at higher residence time.
Fulltext Effect of petroleum derivatives and solvents on colour perception

Sharanjeet-Kaur, Mursyid A, Kamaruddin A, Ariffin A

Clin Exp Optom, 2004 Jul;87(4-5):339-43.
PMID: 15312037 DOI: 10.1111/j.1444-0938.2004.tb05064.x

BACKGROUND: Occupational exposure to various neurotoxic chemicals has been shown to be associated with colour vision impairment. It seems that this can occur at low exposure levels, sometimes well below the recommended occupational threshold limits. This study was undertaken to determine the effect of exposure to petroleum derivatives (polyethylene, polystyrene) and solvents (perchloroethylene) on colour perception.
METHODS: Colour vision was assessed using the Ishihara plates, the D-15 test and the Farnsworth Munsell 100 Hue test. Two factories using petroleum derivatives and three dry cleaning premises were chosen at random. A total of 93 apparently healthy employees were recruited from the five workplaces. Two age-matched control groups comprising 56 people, who were support staff of the university with no exposure to petroleum, solvents or their derivatives, were also recruited.
RESULTS: All subjects passed the Ishihara test, showing that none had a congenital red-green defect. Some of the exposed employees failed the D-15 and had abnormally high FM100 Hue scores. All control subjects passed all the colour vision tests. The D-15 test showed that 28 per cent (26 of 93) of exposed employees had a colour vision defect whereas the FM 100 Hue test found that 63 per cent (59 of 93) had a colour vision defect. Most defects were of the blue-yellow type (22.6 per cent) when using the D-15 test. However, with the FM 100 Hue test, most defects were of the non-polar type with no specific axis (50.5 per cent). Mean total error scores calculated from the FM100 Hue test for exposed employees were statistically significantly higher than those of the control subjects.
CONCLUSION: Employees directly exposed to petroleum derivatives and solvents have a higher risk of acquiring colour vision defects compared to subjects who are not.
Study sites: Factories; the control subjects were tested at the Optometry Clinic in Universiti Kebangsaan Malaysia, Kuala Lumpur, Malaysia.
Assessing the Performance of a Real-Time Total Adenylate (ATP+ADP+AMP) Detection Assay for Surface Hygiene Monitoring in Food Manufacturing Plants and Commercial Kitchens

Ching CL, Kamaruddin A, Rajangan CS

J Food Prot, 2021 Jun 01;84(6):973-983.
PMID: 33232455 DOI: 10.4315/JFP-20-294

ABSTRACT: Environmental hygiene monitoring in the food processing environment has become important in current food safety programs to ensure safe food production. However, conventional monitoring of surface hygiene based on visual inspection and microbial counts is slow, tedious, and thus unable to support the current risk-based management system. Therefore, this study was conducted to assess the performance of a real-time total adenylate assay that detected ATP+ADP+AMP (A3) for food contact surface hygiene in 13 food processing plants and two commercial kitchens in Malaysia. The A3 value was compared with the microbial count (aerobic plate count [APC]) on food contact surfaces. Receiver-operating characteristic (ROC) analysis was performed to assess the reliability of the data and to determine the optimal threshold value for hygiene indication of food contact surfaces. Overall, the A3 value demonstrated a weak positive relationship with APC. However, the A3 value significantly correlated with APC for food processing environments associated with raw meat and raw food ingredients such as fruit that harbor a high microbial load. ROC analysis suggested an optimal threshold for the A3 value of 500 relative light units to balance the sensitivity and specificity at 0.728 and 0.719, respectively. The A3 assay as a hygiene indicator for food contact surfaces had an efficiency of 72.1%, indicating its reliability as a general hygiene indicator.
Optimization studies on acid hydrolysis of oil palm empty fruit bunch fiber for production of xylose

Rahman SH, Choudhury JP, Ahmad AL, Kamaruddin AH

Bioresour Technol, 2007 Feb;98(3):554-9.
PMID: 16647852

Oil palm empty fruit bunch fiber is a lignocellulosic waste from palm oil mills. It is a potential source of xylose which can be used as a raw material for production of xylitol, a high value product. The increasing interest on use of lignocellulosic waste for bioconversion to fuels and chemicals is justifiable as these materials are low cost, renewable and widespread sources of sugars. The objective of the present study was to determine the effect of H(2)SO(4) concentration, reaction temperature and reaction time for production of xylose. Batch reactions were carried out under various reaction temperature, reaction time and acid concentrations and Response Surface Methodology (RSM) was followed to optimize the hydrolysis process in order to obtain high xylose yield. The optimum reaction temperature, reaction time and acid concentration found were 119 degrees C, 60 min and 2%, respectively. Under these conditions xylose yield and selectivity were found to be 91.27% and 17.97 g/g, respectively.
Modelling on the effect of diffusive and convective substrate transport for biofilm

Khabibor Rahman N, Bakar MZ, Hekarl Uzir M, Harun Kamaruddin A

Math Biosci, 2009 Apr;218(2):130-7.
PMID: 19563738 DOI: 10.1016/j.mbs.2009.01.007

A one-dimensional biofilm model was developed based on the basic principle of conservation of mass. Three simple, generic processes were combined in the model which includes microbial growth, diffusive and convective mass transport. The final model could generate a quantitative description of the relationship between the microbial growth and the consumption of substrate (oxygen) within the fixed biofilm thickness. Mass transfer resistance contributes large influence on the substrates and microbial concentration across the biofilm thickness due to the effect of biofilm structure.
Antinociceptive and antiinflammatory activities of the aqueous extract of Trigonopleura malayana resin in experimental animal models

Sulaiman MR, Zakaria ZA, Kamaruddin A, Meng TF, Ali DI, Moin S

Methods Find Exp Clin Pharmacol, 2008 Nov;30(9):691-6.
PMID: 19229377 DOI: 10.1358/mf.2008.30.9.1305824

Trigonopleura malayana L. (Euphorbiaceae) resin, locally known as Gambir Sarawak, has been used traditionally to alleviate pain associated with insect bites, muscle ache, toothache and minor injuries. The present study was carried out using various animal models to determine the antinociceptive and antiinflammatory activities of the T. malayana resin aqueous extract. Antinociceptive activity was measured using the abdominal constriction, hot plate and formalin tests, while antiinflammatory activity was measured using the carrageenan-induced paw edema test. The extract, obtained after 24 h of soaking the dried resin in distilled water, was prepared in doses of 0.3, 3 and 10 mg/kg and administered subcutaneously 30 min prior to the assays. The mechanism of action was also determined by prechallenging with naloxone (10 mg/kg), a nonselective opioid antagonist. The extract was found to exhibit significant (P < 0.05) and dose-dependent antinociceptive and antiinflammatory activities; naloxone failed to inhibit the former activity. In conclusion, the aqueous extract of T. malayana resin possesses nonopioid antinociceptive and antiinflammatory activities, thus supporting previous claims regarding its traditional use by the Malays to treat various ailments, particularly those related to pain.
Investigation of the links between heterocyst and biohydrogen production by diazotrophic cyanobacterium A. variabilis ATCC 29413

Salleh SF, Kamaruddin A, Uzir MH, Karim KA, Mohamed AR

Arch Microbiol, 2016 Mar;198(2):101-13.
PMID: 26521065 DOI: 10.1007/s00203-015-1164-6

This work investigates the effect of heterocyst toward biohydrogen production by A. variabilis. The heterocyst frequency was artificially promoted by adding an amino acid analog, in this case DL-7-azatryptophan into the growth medium. The frequency of heterocyst differentiation was found to be proportional to the concentration of azatryptophan (0-25 µM) in the medium. Conversely, the growth and nitrogenase activity were gradually suppressed. In addition, there was also a distinct shortening of the cells filaments and detachment of heterocyst from the vegetative cells. Analysis on the hydrogen production performance revealed that both the frequency and distribution of heterocyst in the filaments affected the rate of hydrogen production. The highest hydrogen production rate and yield (41 µmol H2 mg chl a(-1) h(-1) and 97 mL H2 mg chl a(-1), respectively) were achieved by cells previously grown in 15 µM of azatryptophan with 14.5 % of heterocyst frequency. The existence of more isolated heterocyst has been shown to cause a relative loss in nitrogenase activity thus lowering the hydrogen production rate.
Kinetic modeling of hydrogen production rate by photoautotrophic cyanobacterium A. variabilis ATCC 29413 as a function of both CO2 concentration and oxygen production rate

Salleh SF, Kamaruddin A, Uzir MH, Mohamed AR, Shamsuddin AH

Prep Biochem Biotechnol, 2017 Feb 07;47(2):111-115.
PMID: 27143318 DOI: 10.1080/10826068.2016.1181085

Hydrogen production by cyanobacteria could be one of the promising energy resources in the future. However, there is very limited information regarding the kinetic modeling of hydrogen production by cyanobacteria available in the literature. To provide an in-depth understanding of the biological system involved during the process, the Haldane's noncompetitive inhibition equation has been modified to determine the specific hydrogen production rate (HPR) as a function of both dissolved CO2 concentration (CTOT) and oxygen production rate (OPR). The highest HPR of 15 [Formula: see text] was found at xCO2 of 5% vol/vol and the rate consequently decreased when the CTOT and OPR were 0.015 k mol m(-3) and 0.55 mL h(-1), respectively. The model provided a fairly good estimation of the HPR with respect to the experimental data collected.
Alignment efficiency and esthetic performance of 4 coated nickel-titanium archwires in orthodontic patients over 8 weeks: A multicenter randomized clinical trial

Ulhaq A, Esmail Z, Kamaruddin A, Meadows S, Daus J, Vitale M, et al.

Am J Orthod Dentofacial Orthop, 2017 Dec;152(6):744-752.
PMID: 29173854 DOI: 10.1016/j.ajodo.2017.07.014

INTRODUCTION: The objective of this 4-arm parallel study was to evaluate the alignment efficiency and esthetic performance of 4 coated nickel-titanium archwires over an 8-week period.
METHODS: Patients in the permanent dentition requiring maxillary and mandibular fixed orthodontic treatment with a preadjusted edgewise appliance were eligible for inclusion. Patients attending 4 hospital departments (United Kingdom and Italy) were randomly allocated to 1 of 4 treatment interventions: (1) BioCosmetic (Forestadent, Pforzheim, Germany), 0.017 in; (2) Titanol (Forestadent), 0.016 in; (3) TP Aesthetic (TP Orthodontics, La Porte, Ind), 0.014 in; and (4) Tooth Tone (Ortho Organizers, Calsbad, Calif) 0.016 in. Block randomization with block sizes of 4 and 8 was used to ensure an allocation ratio of 1:1:1:1. The primary outcome was alignment efficiency determined by the reduction in Little's irregularity index (mm). Secondary outcomes were color change using the Commission Internationale de L'Eclairage L*a*b* system and percentage of coating loss. Blinding was only applicable to outcome assessment of alignment efficiency. Regression models with Sidak's multiple comparison of means were used to analyze the data.
RESULTS: One hundred fifty patients (300 dental arches) were allocated to the treatment interventions, including 61 male and 89 female subjects with a mean age of 16.60 years. The average duration of follow-up was 63.65 days. Baseline characteristics for the archwire groups were similar. One patient was lost to follow-up. Five percent (n = 15) of the archwires fractured: BioCosmetic, 5.3% (n = 4); Titanol, 6.8% (n = 5); TP Aesthetic, 5.3% (n = 4); and Tooth Tone, 2.7% (n = 2). We analyzed 283 dental arches for alignment efficiency. There was no statistically significant difference for mean reduction in irregularity between the archwire groups (P = 0.627): BioCosmetic (n = 71), 3.86 mm (95% CI, 3.31-4.41); Titanol (n = 69), 4.51 mm (95% CI, 4.00-5.02); TP Aesthetic (n = 71), 4.13 mm (95% CI, 3.49-4.78); and Tooth Tone (n = 72), 4.21 mm (95% CI, 3.89-4.46). There was a statistically significant difference between archwire groups for color change (P = 0.001) and percentage of coating loss (P = 0.001), with BioCosmetic performing best in both parameters.
CONCLUSIONS: There was no difference between the archwires for alignment efficiency. BioCosmetic performed statistically significantly better than did the other groups for both color change and coating loss.
REGISTRATION: This trial was registered with the East Midlands NHS Research Ethics Committee (12/EM/0190).
PROTOCOL: The protocol was not published before trial commencement.
Fulltext Nurses' Perception and Satisfaction Toward Electronic Medical Record System

Ramoo V, Kamaruddin A, Wan Nawawi WNF, Che CC, Kavitha R

Florence Nightingale J Nurs, 2023 Feb;31(1):2-10.
PMID: 36751711 DOI: 10.5152/FNJN.2022.22061

AIM: This study aims to assess the perception and satisfaction of nurses toward the electronic medical record system in a teaching hospital.
METHOD: A cross-sectional study was conducted among 350 nurses in a teaching hospital via a self-administered questionnaire between May to October 2019. Descriptive analysis, independent t-test, analysis of variance, and hierarchical multiple regression were used to analyze the data using Statistical Package for Social Sciences software version 25. In addition, a The Strengthening the Reporting of Observational Studies in Epidemiology (STROBE) was used as guide in reporting the results of this study.
RESULTS: Almost all the nurses (98%, n = 343) had a positive perception toward the electronic medical record system, though their perceptions significantly differ across work units, computer or laptop ownership, and daily time spent on the system (all p < .05). Nurses who had received training reported better satisfaction with the system.
CONCLUSION: Among the issues highlighted by the participants that warrant attention were system development and connectivity. This study, therefore, emphasizes the involvement of nursing personnel in system development to ensure an appropriate approach for nursing care delivery.
An evaluation of digital intervention for perinatal depression and anxiety: A systematic review

Arifin SRM, Kamaruddin A, Muhammad NA, Nurumal MS, Mohadis HM, Hussain NHN, et al.

AIMS Public Health, 2024;11(2):499-525.
PMID: 39027400 DOI: 10.3934/publichealth.2024025

Digital intervention has been shown to be helpful in improving perinatal mental health. However, the design characteristics of such interventions have not been systematically reviewed. Considering that a lack of support-especially from a partner-is one of the major contributing factors to perinatal depression and anxiety, it is crucial to determine whether digital interventions have included partner participation. In this review, we systematically examined the design characteristics of digital interventions related to perinatal depression and anxiety and aimed to determine whether partner participation was incorporated as part of the interventions. Based on the PRISMA 2020 guidelines, five databases (PubMed, EBSCO, Cochrane, ProQuest, and Scopus) were searched. Narrative results of design characteristics were developed to provide a framework for the design and evaluation of the studies. A total of 12 intervention studies from China, Sweden, Australia, New Zealand, Singapore, Norway, and the United Kingdom were included. Across all studies, internet cognitive behavioral therapy and mindfulness therapy were overwhelmingly utilized as the major intervention approaches. While all studies reported reduced depressive symptoms after the intervention, only four studies reported subsequent decreased levels of both depressive and anxiety symptoms. Only one study included partner support in the intervention. Cognitive behavioral therapy and mindfulness therapy, two of the most common intervention approaches, were found to be effective in alleviating perinatal depression and anxiety. Partner participation should be prioritized in designing digital interventions to ensure comprehensive and easily accessible social support for persons in need.

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