In Vitro Pharmacodynamic Profile of Loranthus ferrugineus: Evidence for Noncompetitive Antagonism of Norepinephrine-induced Vascular Contraction

Omar Z. Ameer,Ibrahim M. Salman,Hafsa S. Najim,Ghassan Z. Abdullah,Muthanna F. Abdulkarim,Mun Fei Yam,Amirin Sadikun,Mohamed Z. Asmawi 사단법인약침학회 2010 Journal of Acupuncture & Meridian Studies Vol.3 No.4

The mode by which Loranthus ferrugineus methanol extract antagonizes and/or modulates norepinephrine-induced vasoconstriction was investigated in rat aortic rings. The vascular effects of three different concentrations of this extract were challenged against cumulative additions of norepinephrine. Phentolamine,a nonselective α-adrenoceptor antagonist, verapamil, an L-type calcium channel blocker, and papaverine, a phosphodiesterase inhibitor, were used in three different concentrations as positive controls. Log concentration-response curves and double-reciprocal plots were constructed for the extract and each vasorelaxant. To characterize antagonism reversibility, the norepinephrine maximum contractile effect was examined before extract addition to the aortic ring chamber and after its removal. Phentolamine shifted the norepinephrine log concentration-response curve to the right with no significant depression in the maximum response. Similar to verapamil and papaverine, the extract produced a rightward shift in norepinephrine log concentration-response curve and a significant drop in maximum response. The double-reciprocal plots showed comparable y-intercept values for all phentolamine concentrations, a characteristic of competitive antagonism. In contrast, different y-intercept values on double-reciprocal plots were obtained for each concentration of extract, verapamil, and papaverine, typical of noncompetitive antagonism. The norepinephrine maximum contractile response was approximately similar before the addition of extract and after its removal. The data collectively showed that L. ferrugineus methanol extract exerted its vascular effect by reversible noncompetitive antagonism of norepinephrine-induced vasoconstriction. These findings add to the understanding of the cardiovascular mechanisms by which L. ferrugineus, a plant traditionally used for the management of hypertension, elicits its action.

Hybrid Electrically Conductive Adhesive (HECA) Properties as a Function of Hybrid Filler Ratio With Increasing Total Filler Loading

Z. Adnan,S. H. S. M. Fadzullah,G. Omar,Z. Mustafa,M. B. Ramli,N. Razali,A. A. Kamarolzaman 대한금속·재료학회 2021 ELECTRONIC MATERIALS LETTERS Vol.17 No.4

This paper presents a study on Hybrid Electrically Conductive Adhesive (HECA) properties as an in-depth analysis regardinghybrid fi ller ratio at low fi ller range. It is well established that the hybridization approach exhibits excellent functionalproperties of HECA. Still, the highest potential ability of the proposed HECA concerning relative amounts of involvingfi llers is the least being discovered. In this work, silver micro-fl ake (AgMF) and multiwalled carbon nanotube (MWCNT)conductive fi llers were incorporated from 3 to 15 wt.%, while AgMF: MWCNT fi ller ratio is varied between 0.006 up to 0.2to choose the best combination. Here, a planetary centrifugal mixer with diff erent mixing time and sequence were consideredto identify the most eff ective mixing method. The functional properties of HECA were characterized in terms of a four-pointprobe electrical test and a lap shear test via tensile mode. The morphological study suggests that a shorter centrifugal mixingperiod allows an adequate dispersion of the micro-nano fi llers in the HECA system and revealed superior interfacial bondingbetween the fi llers at the optimum ratio. Interestingly, electrical resistivity at critical concentration showed an optimumratio by incorporating only 2.5% AgMF in the hybrid fi llers to yield a 42.62% reduction. However, the signifi cant eff ects ofhybridization are observed until the percolation threshold of HECA at 9 wt% only, followed by a 38.5% reduction beyondthis limit. Moreover, the lap shear strength is most reliable at a total fi ller of 6 wt%, an indication of an excellent fi ller-binderload distribution.

Orthosiphon stamineus: Traditional Uses, Phytochemistry, Pharmacology, and Toxicology

Omar Z. Ameer,Ibrahim M. Salman,Mohammad Zaini Asmawi,Zaid O. Ibraheem,Mun Fei Yam 한국식품영양과학회 2012 Journal of medicinal food Vol.15 No.8

Orthosiphon stamineus Benth. (Lambiaceae) is an important plant in traditional folk medicine. This review is a comprehensive summary of the currently available chemical, pharmacological, and toxicological investigations as well as the traditional and therapeutic uses of this plant. Different in vitro and in vivo models have been addressed along with a survey of all phytochemicals identified in this plant, including flavonoids, terpenoids, and essential oils. Previous studies revealed that O. stamineus possesses several pharmacological activities, which are attributed to its phytochemical content. It was found that O. stamineus exhibits diuretic, hypouricemic, renal protective, antioxidant, anti-inflammatory, hepatoprotective, gastroprotective, antihypertensive, antidiabetic, antihyperlipidemic, antimicrobial, and anorexic activities. In conclusion, O. stamineus has wide traditional and pharmacological uses in various pathophysiological conditions. Therefore, it is an attractive subject for further experimental and clinical investigations.

Loranthus ferrugineus: a Mistletoe from Traditional Uses to Laboratory Bench

Omar Z. Ameer,Ibrahim M. Salman,Ko Jin Quek,Mohd. Z. Asmawi 대한약침학회 2015 Journal of pharmacopuncture Vol.18 No.1

Objectives: Loranthus ferrugineus (L. ferrugineus) from Loranthaceae, a mistletoe, is a medicinal herb used for a variety of human ailments. Traditionally, decoctions of this parasitic shrub have been mainly used to treat high blood pressure (BP) and gastrointestinal complaints; usage which is supported by experimental based pharmacological investigations. Nonetheless, there is still limited data available evaluating this plant’s traditions, and few studies have been scientifically translated toward evidence based phytomedicine. We therefore provide a concise review of the currently available L. ferrugineus literature and discuss potential directions for future areas of investigation. Methods: We surveyed available literature covering ethnopharmacological usage of L. ferrugineus and discussed relevant findings, including important future directions and shortcomings for the medicinal values of this parasitic shrub. Results: Evidence based pharmacological approaches significantly covered the medicinal application of L. ferrugineus for hypertension and gastrointestinal complaint management, with a particular focus on the active hydrophilic extract of this herb. Conclusion: Understanding the sites of action of this plant and its beneficial effects will provide justification for its use in old traditional treatments, and potentially lead to the development of therapies. Other medicinal applicative areas of this parasitic shrub, such as wound healing, gerontological effects, and antiviral and anticancer activities, are yet to be researched.

Loranthus ferrugineus: a Mistletoe from Traditional Uses to Laboratory Bench

Ameer, Omar Z.,Salman, Ibrahim M.,Quek, Ko Jin,Asmawi, Mohd. Z. KOREAN PHARMACOPUNCTURE INSTITUTE 2015 Journal of pharmacopuncture Vol.18 No.1

Objectives: Loranthus ferrugineus (L. ferrugineus) from Loranthaceae, a mistletoe, is a medicinal herb used for a variety of human ailments. Traditionally, decoctions of this parasitic shrub have been mainly used to treat high blood pressure (BP) and gastrointestinal complaints; usage which is supported by experimental based pharmacological investigations. Nonetheless, there is still limited data available evaluating this plant's traditions, and few studies have been scientifically translated toward evidence based phytomedicine. We therefore provide a concise review of the currently available L. ferrugineus literature and discuss potential directions for future areas of investigation. Methods: We surveyed available literature covering ethnopharmacological usage of L. ferrugineus and discussed relevant findings, including important future directions and shortcomings for the medicinal values of this parasitic shrub. Results: Evidence based pharmacological approaches significantly covered the medicinal application of L. ferrugineus for hypertension and gastrointestinal complaint management, with a particular focus on the active hydrophilic extract of this herb. Conclusion: Understanding the sites of action of this plant and its beneficial effects will provide justification for its use in old traditional treatments, and potentially lead to the development of therapies. Other medicinal applicative areas of this parasitic shrub, such as wound healing, gerontological effects, and antiviral and anticancer activities, are yet to be researched.

Endocrine disrupting compounds (EDCs) in environmental matrices: Review of analytical strategies for pharmaceuticals, estrogenic hormones, and alkylphenol compounds

Omar, T.F.T.,Ahmad, A.,Aris, A.Z.,Yusoff, F.M. Elsevier Scientific Pub. Co 2016 Trends in analytical chemistry Vol.85 No.3

Endocrine disrupting compounds (EDCs) have been widely reported as potential carcinogenic threats to the human population. The release of EDCs to environmental compartments, such as water, sediment, and biota, has been monitored extensively. Considering the typically low levels of EDC concentrations found in environmental samples and the complexity of biota matrices, the main challenge is with the extraction and cleanup of samples, as well as with finding a sensitive enough instrumentation system for analyte detection. This paper presents a review of recent trends in the analysis of EDCs in environmental matrices. The focus of this review is three classes of environmentally important EDCs; namely, pharmaceuticals, estrogenic hormones, and alkylphenol compounds. Discussions about state-of-the-art instrumentation and sample preparation techniques, as well as a review of sample storage and preservation, are highlighted. Overall, the use of LC-MS-MS as an instrumentation technique has increased over the past 15 years.

Strength of Thixoformed A319 Alloy at Elevated Temperature

A. M. Aziz,M. Z. Omar,Z. Sajuri 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.7

When alloys are exposed to elevated temperatures they experience a decrement in their mechanical properties that leadsto material failure. However, the use of thixoforming, an alternative metal processing method, could enhance mechanicalproperties by minimising the defects that exist in as-received alloys. Therefore, this study aimed to determine the tensilestrength of thixoformed A319 under elevated temperatures by taking into account its intended use in vehicle cylinder headcomponents. Thixoformed A319 was compared with as-received alloy manufactured by permanent mould casting. Thecooling slope method was used to prepare the feedstock for thixoforming. The feedstock was reheated by induction heatinguntil it reached 574 °C and was then formed in a mould. Afterwards, the as-received and thixoformed samples underwentT6 heat treatment. The resulting samples were characterised by using optical microscopy, scanning electron microscopyequipped with energy dispersive X-ray, X-ray difraction analysis and a tensile test. Elevated temperature tensile tests wereperformed at 250 °C, in line with the temperature condition experienced by cylinder head components during operation. The ultimate tensile strength of the thixoformed samples was 30% higher than that of the as-received samples under elevatedtemperatures. Also, the analyses of the fracture surfaces showed that porosity, intermetallic compounds and impurities wereamongst the failure factors for both alloys.

Validation of competing structural models of inter-relationships in the teaching–learning ecosystem for two Malaysian STEM courses

P. Davidson,S. Roslan,Z. Omar,M. Chong Abdullah,S. Y. Looi,T. T. X. Neik,B. Yong 서울대학교 교육연구소 2019 Asia Pacific Education Review Vol.20 No.1

This study reported the results of Structural Equation Modelling (SEM) analyses on 13 competing structural models on the inter-relationships among academic achievement and student- and course-related attributes. The samples were Malaysian preuniversity students enrolled in two STEM courses (biology, n=326; mathematics, n=339; biology only, n=92; mathematics only, n=105; biology and mathematics, n=234). For both courses, interdisciplinary cross-validation was observed for four models which hypothesized that current academic achievement could be predicted (1) directly by prior academic achievement (high school grades) and student approaches to learning (SAL), and (2) directly and/or indirectly by personality, intrinsic motivation and course experience (CE). For at least one course, all constructs (except intrinsic motivation, clear goals and standards, openness and conscientiousness) significantly and directly predicted current academic achievement. The strongest predictor of current academic achievement was prior (high school) academic achievement, with the largest effect sizes, followed by SAL. Current academic achievement was significantly and positively predicted by all CE constructs (except clear goals and standards) for only mathematics, with moderate and large effect sizes. Only one personality construct (neuroticism) significantly and moderately predicted current academic achievement (biology). SAL partially mediated relationships between current academic achievement with workload appropriateness, assessment for understanding and neuroticism for at least one course. Generally, the strongest predictors of SAL were assessment for understanding, workload appropriateness and intrinsic motivation. Multigroup invariance analysis revealed differences in five hypothesized paths, attributable almost entirely to significant paths found in mathematics but not biology (prior [high school] to current academic achievement, conscientiousness to surface approach to learning, intrinsic motivation to deep and surface approaches to learning). Therefore, this study is the first to report course-nuanced differences in the presence of reduced interpersonal differences. The implications of this study is that, besides the importance of prior high academic achievement which might not be within educators’ control, factors in the teaching–learning ecosystem within educators’ control which influence current academic achievement are strongly mediated by SAL, which is itself influenced most by assessment, workload and intrinsic motivation.

Design of artificial neural network using particle swarm optimisation for automotive spring durability

Y. S. Kong,S. ABDULLAH,D. Schramm,M. Z. Omar,S. M. Haris 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.11

This paper presents the optimisation of spring fatigue life based on an artificial neural network (ANN) architecture and particle swarm optimisation algorithm (PSO) using ISO 2631 vertical vibration as input. The road-induced vibration of a ground vehicle caused the spring to fail due to fatigue and human discomfort. Hence, there is a need to model the relationship between these two parameters for spring design assistance. Vibration and force signals were extracted from a quarter car model simulation for fatigue life and ISO 2631 vertical vibration estimations. PSO was applied to the datasets for ANN weights and biases adjustments while the mean squared error (MSE) was set as the objective function. For validation purposes, a set of independent datasets was applied to the ANN. The residuals were analysed using Lilliefors normality and error histogram. For prediction accuracy, the predicted fatigue lives were analysed using scatter band approach and compared with traditional trained ANN. The results have shown that most of the PSO-based ANN predicted fatigue lives were in the acceptable region and the root mean square error (RMSE) value of 0.6391 life cycles in natural logarithm was obtained. The PSO-based ANN has shown improved performance compared to the conventional ANN approach in predicting fatigue life.

Investigating the Physiological Responses of Farm Tractor Operators during Ronnie Baugh Tractor (Oggun II) Operation in a Controlled Static Environment

Mark Gerard S. Cruz,Stephanie Caridad DR. Landicho,John Kenneth P. Punongbayan,Diana Marie R. De Silva,Haerold Dean Z. Layaoen,Josefa Angelie D. Revilla,Omar F. Zubiab 대한산업공학회 2024 Industrial Engineeering & Management Systems Vol.23 No.2

Rural areas in the Philippines rely on agriculture as one of the main sources of employment. The use of the traditional 4-wheel tractor is expensive; hence Ronnie Baugh Tractor (RBT) aims to address this concern. RBT is an opensystem tractor with lighter and more economical features than the traditional tractor. Being newly introduced, safety evaluations are vital to ensure its suitability for short- and long-term usage. This study determines reference values of vibration and physiological responses during static RBT operation. Fourteen experienced tractor operators were recruited and instructed to perform thirteen tasks common in tractor operation. Muscle activities and vibrations were measured and recorded. Subjective discomfort and comfort ratings were assessed. RBT vibration on various locations exceeded the safe values because the engine only had metal support without dampeners. Forearm muscle activation was significantly higher than the upper arm and leg during the performance of most tasks. Leg muscle also exhibited mild to moderate exertion in some tasks. Left upper limb had a significantly higher activation than the right side. Overall, the observed muscle reactions were associated with the general design and with the level of RBT vibration across various parts. Finally, recommendations including design improvements were suggested.