Mohamad Haris - Academia.edu (original) (raw)

Papers by Mohamad Haris

Nature Medicine, 2012

Glutamate, a major neurotransmitter in the brain, shows a pHand concentration-dependent chemical ... more Glutamate, a major neurotransmitter in the brain, shows a pHand concentration-dependent chemical exchange saturation transfer effect (GluCEST) between its amine group and bulk water, with potential for in vivo imaging by nuclear magnetic resonance. GluCEST asymmetry is observed ~3 p.p.m. downfield from bulk water. Middle cerebral artery occlusion in the rat brain resulted in an ~100% elevation of GluCEST in the ipsilateral side compared with the contralateral side, predominantly owing to pH changes. In a rat brain tumor model with blood-brain barrier disruption, intravenous glutamate injection resulted in a clear elevation of GluCEST and a similar increase in the proton magnetic resonance spectroscopy signal of glutamate. GluCEST maps from healthy human brain were also obtained. These results demonstrate the feasibility of using GluCEST for mapping relative changes in glutamate concentration, as well as pH, in vivo. Contributions from other brain metabolites to the GluCEST effect are also discussed. Glutamate and γ-aminobutyric acid (GABA) are the major excitatory and inhibitory neurotransmitters, respectively, in the brain and are likely involved in nearly all signal processing functions of the central nervous system (CNS) and altered in many CNS diseases 1-4. Magnetic resonance imaging (MRI) is a noninvasive imaging technique that provides exquisite structural detail, but current MRI methods are not capable of imaging the distribution of neurotransmitters in brain (Supplementary Note). Proton magnetic resonance spectroscopy (1 H MRS) can detect several neurotransmitter signature groups using a variety of techniques 5-10. However, 1 H MRS techniques require long acquisition times and have poor spatial resolution. Here we describe a new MRI technique for imaging glutamate (R.R., K.C., M.H., A.S., F.K. and H.H., unpublished data) based on its chemical exchange saturation transfer (CEST) effect 11-15. GluCEST provides markedly higher spatial and temporal resolution compared with 1 H MRS. The CEST effect from amide and hydroxyl protons from different amino acids, proteins and other molecules 12,16,17 have previously been exploited to measure pH in vivo 18,19 , glycogen in the liver 20 , glycosaminoglycans in cartilage 21 , gene expression in vivo 22 and myo-inositol in brain 23 , but no prior studies have used the CEST effect of amine protons to image glutamate in vivo. Here the pH and concentration dependence of GluCEST is first demonstrated in vitro at 37 °C. Second, the feasibility of measuring GluCEST in vivo from rat brain with and without focal ischemia is shown. Third, changes in GluCEST and glutamate 1 H MRS in response to exogenous injection of glutamate in a rat brain tumor model are compared. Finally, the feasibility of mapping the glutamate signal from healthy human brain in vivo is demonstrated at 7 Tesla (7T), an ultrahigh-field whole-body imaging scanner. The potential contributions to GluCEST from other brain metabolites, as well as the advantages and shortcomings of this approach, are also discussed.

Leave of absence is time allowed away from work which requested by an employee to cover unusual c... more Leave of absence is time allowed away from work which requested by an employee to cover unusual circumstances occurring in their life. Rapid development in technology enables things to be accessible through smartphone. Leave Recommender Mobile Application is designed to help recommending and handling the process in applying leave in a much more effective and efficient way. This system help to plan the employee leave by giving recommendation on the suitable date for applying leave. Besides, the systems can also handle leave application and reject or approve leave application. This system will be using Android as its platform. Mobile application development life cycles are adapted in this project in order to achieve the objectives. This project will give recommendation based on the rules by using rule based recommender system. Eight rules are used in this project and the rules are gathered from the interview with the expert in UiTM Jasin.

Scientific Reports

Malaysia is a country with an intermediate endemicity for hepatitis B. As the country moves towar... more Malaysia is a country with an intermediate endemicity for hepatitis B. As the country moves toward hepatitis B and C elimination, population-based estimates are necessary to understand the burden of hepatitis B and C for evidence-based policy-making. Hence, this study aims to estimate the prevalence of hepatitis B and C in Malaysia. A total of 1458 participants were randomly selected from The Malaysian Cohort (TMC) aged 35 to 70 years between 2006 and 2012. All blood samples were tested for hepatitis B and C markers including hepatitis B surface antigen (HBsAg), anti-hepatitis B core antibody (anti-HBc), antibodies against hepatitis C virus (anti-HCV). Those reactive for hepatitis C were further tested for HCV RNA genotyping. The sociodemographic characteristics and comorbidities were used to evaluate their associated risk factors. Descriptive analysis and multivariable analysis were done using Stata 14. From the samples tested, 4% were positive for HBsAg (95% CI 2.7–4.7), 20% were ...

Nature Medicine, 2012

Glutamate, a major neurotransmitter in the brain, shows a pHand concentration-dependent chemical ... more Glutamate, a major neurotransmitter in the brain, shows a pHand concentration-dependent chemical exchange saturation transfer effect (GluCEST) between its amine group and bulk water, with potential for in vivo imaging by nuclear magnetic resonance. GluCEST asymmetry is observed ~3 p.p.m. downfield from bulk water. Middle cerebral artery occlusion in the rat brain resulted in an ~100% elevation of GluCEST in the ipsilateral side compared with the contralateral side, predominantly owing to pH changes. In a rat brain tumor model with blood-brain barrier disruption, intravenous glutamate injection resulted in a clear elevation of GluCEST and a similar increase in the proton magnetic resonance spectroscopy signal of glutamate. GluCEST maps from healthy human brain were also obtained. These results demonstrate the feasibility of using GluCEST for mapping relative changes in glutamate concentration, as well as pH, in vivo. Contributions from other brain metabolites to the GluCEST effect are also discussed. Glutamate and γ-aminobutyric acid (GABA) are the major excitatory and inhibitory neurotransmitters, respectively, in the brain and are likely involved in nearly all signal processing functions of the central nervous system (CNS) and altered in many CNS diseases 1-4. Magnetic resonance imaging (MRI) is a noninvasive imaging technique that provides exquisite structural detail, but current MRI methods are not capable of imaging the distribution of neurotransmitters in brain (Supplementary Note). Proton magnetic resonance spectroscopy (1 H MRS) can detect several neurotransmitter signature groups using a variety of techniques 5-10. However, 1 H MRS techniques require long acquisition times and have poor spatial resolution. Here we describe a new MRI technique for imaging glutamate (R.R., K.C., M.H., A.S., F.K. and H.H., unpublished data) based on its chemical exchange saturation transfer (CEST) effect 11-15. GluCEST provides markedly higher spatial and temporal resolution compared with 1 H MRS. The CEST effect from amide and hydroxyl protons from different amino acids, proteins and other molecules 12,16,17 have previously been exploited to measure pH in vivo 18,19 , glycogen in the liver 20 , glycosaminoglycans in cartilage 21 , gene expression in vivo 22 and myo-inositol in brain 23 , but no prior studies have used the CEST effect of amine protons to image glutamate in vivo. Here the pH and concentration dependence of GluCEST is first demonstrated in vitro at 37 °C. Second, the feasibility of measuring GluCEST in vivo from rat brain with and without focal ischemia is shown. Third, changes in GluCEST and glutamate 1 H MRS in response to exogenous injection of glutamate in a rat brain tumor model are compared. Finally, the feasibility of mapping the glutamate signal from healthy human brain in vivo is demonstrated at 7 Tesla (7T), an ultrahigh-field whole-body imaging scanner. The potential contributions to GluCEST from other brain metabolites, as well as the advantages and shortcomings of this approach, are also discussed.

Leave of absence is time allowed away from work which requested by an employee to cover unusual c... more Leave of absence is time allowed away from work which requested by an employee to cover unusual circumstances occurring in their life. Rapid development in technology enables things to be accessible through smartphone. Leave Recommender Mobile Application is designed to help recommending and handling the process in applying leave in a much more effective and efficient way. This system help to plan the employee leave by giving recommendation on the suitable date for applying leave. Besides, the systems can also handle leave application and reject or approve leave application. This system will be using Android as its platform. Mobile application development life cycles are adapted in this project in order to achieve the objectives. This project will give recommendation based on the rules by using rule based recommender system. Eight rules are used in this project and the rules are gathered from the interview with the expert in UiTM Jasin.

Scientific Reports

Malaysia is a country with an intermediate endemicity for hepatitis B. As the country moves towar... more Malaysia is a country with an intermediate endemicity for hepatitis B. As the country moves toward hepatitis B and C elimination, population-based estimates are necessary to understand the burden of hepatitis B and C for evidence-based policy-making. Hence, this study aims to estimate the prevalence of hepatitis B and C in Malaysia. A total of 1458 participants were randomly selected from The Malaysian Cohort (TMC) aged 35 to 70 years between 2006 and 2012. All blood samples were tested for hepatitis B and C markers including hepatitis B surface antigen (HBsAg), anti-hepatitis B core antibody (anti-HBc), antibodies against hepatitis C virus (anti-HCV). Those reactive for hepatitis C were further tested for HCV RNA genotyping. The sociodemographic characteristics and comorbidities were used to evaluate their associated risk factors. Descriptive analysis and multivariable analysis were done using Stata 14. From the samples tested, 4% were positive for HBsAg (95% CI 2.7–4.7), 20% were ...