Hong Anh Nguyen Lam - Academia.edu (original) (raw)

Papers by Hong Anh Nguyen Lam

Infection and Immunity, 1998

The ability of a serotype M1 strain of Streptococcus pyogenes to efficiently invade A549 human lu... more The ability of a serotype M1 strain of Streptococcus pyogenes to efficiently invade A549 human lung epithelial cells was previously shown to be dependent on bacterial exposure to human or bovine serum proteins or synthetic peptides containing the sequence RGD. In this study, stimulation by invasion agonists was determined to be dependent on expression of the streptococcal cell surface protein, M1. Fetal bovine serum (FBS), fibronectin (Fn), the extracellular matrix protein laminin (Lm), and RGD-containing peptides were tested for their abilities to promote epithelial cell invasion and adherence by isogenic M1 + and M1 − strains of S. pyogenes . In the absence of an agonist, invasion and adherence were comparable for the two bacterial strains. FBS, Fn, and Lm stimulated invasion of the M1 + strain as much as 70-fold but failed to significantly affect invasion by the M1 − mutant. Adherence of the wild-type strain was stimulated by these same agonists. Epithelial cell adherence by the ...

British Journal of Pharmacology, 2017

BACKGROUND AND PURPOSE PI3K-dependent activation of Rho kinase (ROCK) is necessary for agonist-in... more BACKGROUND AND PURPOSE PI3K-dependent activation of Rho kinase (ROCK) is necessary for agonist-induced human airway smooth muscle cell (HASMC) contraction, and inhibition of PI3K promotes bronchodilation of human small airways. The mechanisms driving agonist-mediated PI3K/ROCK axis activation, however, remain unclear. Given that G 12 family proteins activate ROCK pathways in other cell types, their role in M 3 muscarinic acetylcholine receptor-stimulated PI3K/ROCK activation and contraction was examined. EXPERIMENTAL APPROACH Gα 12 coupling was evaluated using co-immunoprecipitation and serum response element (SRE)-luciferase reporter assays. siRNA and pharmacological approaches, as well as overexpression of a regulator of G-protein signaling (RGS) proteins were applied in HASMCs. Phosphorylation levels of Akt, myosin phosphatase targeting subunit-1 (MYPT1), and myosin light chain-20 (MLC) were measured. Contraction and shortening were evaluated using magnetic twisting cytometry (MTC) and micro-pattern deformation, respectively. Human precision-cut lung slices (hPCLS) were utilized to evaluate bronchoconstriction. KEY RESULTS Knockdown of M 3 receptors or Gα 12 attenuated activation of Akt, MYPT1, and MLC phosphorylation. Gα 12 coimmunoprecipitated with M 3 receptors, and p115RhoGEF-RGS overexpression inhibited carbachol-mediated induction of SREluciferase reporter. p115RhoGEF-RGS overexpression inhibited carbachol-induced activation of Akt, HASMC contraction, and shortening. Moreover, inhibition of RhoA blunted activation of PI3K. Lastly, RhoA inhibitors induced dilation of hPCLS. CONCLUSIONS AND IMPLICATIONS Gα 12 plays a crucial role in HASMC contraction via RhoA-dependent activation of the PI3K/ROCK axis. Inhibition of RhoA activation induces bronchodilation in hPCLS, and targeting Gα 12 signaling may elucidate novel therapeutic targets in asthma. These findings provide alternative approaches to the clinical management of airway obstruction in asthma.

American Journal of Physiology-Lung Cellular and Molecular Physiology, 2017

Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality. Cigaret... more Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality. Cigarette smoke (CS) drives disease development and progression. The epithelial barrier is damaged by CS with increased monolayer permeability. However, the molecular changes that cause this barrier disruption and the interaction between adhesion proteins and the cytoskeleton are not well defined. We hypothesized that CS alters monolayer integrity by increasing cell contractility and decreasing cell adhesion in epithelia. Normal human airway epithelial cells and primary COPD epithelial cells were exposed to air or CS, and changes measured in protein levels. We measured the cortical tension of individual cells and the stiffness of cells in a monolayer. We confirmed that the changes in acute and subacute in vitro smoke exposure reflect protein changes seen in cell monolayers and tissue sections from COPD patients. Epithelial cells exposed to repetitive CS and those derived from COPD patients have...

Nature communications, Jul 26, 2017

A defining hallmark of primary and metastatic cancers is the migration and invasion of malignant ... more A defining hallmark of primary and metastatic cancers is the migration and invasion of malignant cells. These invasive properties involve altered dynamics of the cytoskeleton and one of its major structural components β-actin. Here we identify AIM1 (absent in melanoma 1) as an actin-binding protein that suppresses pro-invasive properties in benign prostate epithelium. Depletion of AIM1 in prostate epithelial cells increases cytoskeletal remodeling, intracellular traction forces, cell migration and invasion, and anchorage-independent growth. In addition, decreased AIM1 expression results in increased metastatic dissemination in vivo. AIM1 strongly associates with the actin cytoskeleton in prostate epithelial cells in normal tissues, but not in prostate cancers. In addition to a mislocalization of AIM1 from the actin cytoskeleton in invasive cancers, advanced prostate cancers often harbor AIM1 deletion and reduced expression. These findings implicate AIM1 as a key suppressor of invasi...

In this paper, the development and implementation of a direct-coupled building emulator for a bui... more In this paper, the development and implementation of a direct-coupled building emulator for a building energy management and control system (EMCS) is presented. The building emulator consists of a microcomputer and a computer model of an air-conditioning system implemented in a modular dynamic simulation software package for direct-coupling to an EMCS, without using analog-to-digital and digital-to-analog converters. The building emulator can be used to simulate in real time the behavior of the air-conditioning system under a given operating environment and subject to a given usage pattern. Software modules for data communication, graphical display, dynamic data exchange, and synchronization of simulation outputs with real time have been developed to achieve direct digital data transfer between the building emulator and a commercial EMCS. Based on the tests conducted, the validity of the building emulator has been established and the proportional-plus-integral control function of the EMCS assessed.link_to_subscribed_fulltex

The Royal Society of Chemistry eBooks, 2011

... 56. P. Aebischer and J. Ridet, Trends Neurosci., 2001, 24, 533. 57. EF Espejo, RJ Montoro, JA... more ... 56. P. Aebischer and J. Ridet, Trends Neurosci., 2001, 24, 533. 57. EF Espejo, RJ Montoro, JA Armengol and J. Lopez-Barneo, Neuron, 1998, 20, 197. 58. MR Luquin, RJ Montoro, J. Guillen, L. Saldise, R. Insausti, J. Del Rıo and J. Lopez-Barneo, Neuron, 1999, 22, 743. 59. ...

Advances in Meteorology, 2015

This work investigates the physical characteristics of raindrop size distribution (DSD) in an equ... more This work investigates the physical characteristics of raindrop size distribution (DSD) in an equatorial heavy rain region based on three years of disdrometer observations carried out at Universiti Teknologi Malaysia’s (UTM’s) campus in Kuala Lumpur, Malaysia. The natural characteristics of DSD are deduced, and the statistical results are found to be in accordance with the findings obtained from others disdrometer measurements. Moreover, the parameters of the Gamma distribution and the normalized Gamma model are also derived by means of method of moment (MoM) and maximum likelihood estimation (MLE). Their performances are subsequently validated using the rain rate estimation accuracy: the normalized Gamma model with the MLE-generated shape parameterµwas found to provide better accuracy in terms of long-term rainfall rate statistics, which reflects the peculiarities of the local climatology in this heavy rain region. These results not only offer a better understanding of the microphy...

International Journal of Electronics, 2015

This contribution presents a stochastic model useful for the generation of a long-term tropospher... more This contribution presents a stochastic model useful for the generation of a long-term tropospheric rain attenuation time series for Earth space or a terrestrial radio link in tropical and equatorial heavy rain regions based on the well-known Cox-Ingersoll-Ross model previously employed in research in the fields of finance and economics. This model assumes typical gamma distribution for rain attenuation in heavy rain climatic regions and utilises the temporal dynamic of precipitation collected in equatorial Johor, Malaysia. Different formations of survival probability are also discussed. Furthermore, the correlation between these probabilities and the Markov process is determined, and information on the variance and autocorrelation function of rain events with respect to the particular characteristics of precipitation in this area is presented. The proposed technique proved to preserve the peculiarities of precipitation for an equatorial region and reproduce fairly good statistics of the rain attenuation correlation function that could help to improve the prediction of dynamic characteristics of rain fade events.

2014 IEEE Asia-Pacific Conference on Applied Electromagnetics (APACE), 2014

This work evaluates the spatial features of the synthetic rain cell profile based on two years of... more This work evaluates the spatial features of the synthetic rain cell profile based on two years of real rain cells database extracted from weather radar observation located in Kluang, Johor, Malaysia. Single rain cells modeled by an analytical exponential and Gaussian profile are evaluated and investigated based on certain features of real rain cells such as maximum rain rate and root mean square rain rate inside a single rain cell. Preliminary results indicate the Gaussian profile with a shape factor k of 1 best represents real single-peaked rain structures in this particularly heavy rain area. However, the validity of results rely highly on the resolution limitation of the database used in this work, where the commercial operating meteorological radar consists of coarse quantization resolution of rain-rate, which might misinterpret the real rain cell profile at a lower rain rate. Nevertheless, this work still provides radio engineers with useful information for the design of wireless communication systems in this particular area (heavy rain region).

2014 International Symposium on Antennas and Propagation Conference Proceedings, 2014

Satellite communication systems operating at frequencies above 10 GHz are often subject to deep f... more Satellite communication systems operating at frequencies above 10 GHz are often subject to deep fades due to rain attenuation. One of the cost-effective countermeasures that can be used to counteract severe rain attenuation is time diversity. In this paper, performance of time diversity is investigated based on a one-year, Ku-band propagation measurement campaign carried out in heavy rain region. The results found show that the diversity gain increases as a function of time delay. The performance of time diversity is compared with prediction obtained by applying the Stratiform Convective-Synthetic Storm Technique (SC-SST) and a good agreement with measured statistics has been found.

2014 International Symposium on Antennas and Propagation Conference Proceedings, 2014

Advanced satellite communication or modern wireless systems operate at high frequencies will suff... more Advanced satellite communication or modern wireless systems operate at high frequencies will suffer from deep signal fades caused by rain particularly in equatorial region. Meteorological radar operates by MET department is one of the valuable resources to provide the peculiarities of the local precipitation information oriented to the analysis of radio propagation impairments. In this paper, the processing methodology and the interpretation procedure of operational weather radar data are presented from the perspective of such application. The applicability of the processed meteorological radar data is preliminary assessed against Stratiform Convective-Synthetic Storm Technique (SC-SST) in terms of first order rain attenuation statistics. The radar data simulated statistic is found to agree well with the one obtained through SC-SST. This procedure can be useful as a reference methodology for the employment of operational meteorological radar particularly focus on the propagation applications.

2014 XXXIth URSI General Assembly and Scientific Symposium (URSI GASS), 2014

This study is aimed to investigate the relationship between ground wind direction and the seasona... more This study is aimed to investigate the relationship between ground wind direction and the seasonal variation of rain attenuation based on one year of weather station data recorded in Universiti Teknologi Malaysia (UTM), Johor, Malaysia. Preliminary analysis of wind direction based on monsoon seasonal and their impact on rain field advection are carried out to clarify the characteristics of rain attenuation in monsoon season. It is found that rain attenuation is not only affected by the monsoon seasonal variation but it also depends on rain field advection which can be preliminary identified from the wind direction. Such information is useful for the system operators to apply appropriate site diversity techniques during heavy rain events to reduce the system outage in this particular equatorial region.

IEEE Sensors Journal, 2015

ABSTRACT

Nature Protocols, 2014

In the version of this article initially published, the sequence of primer VH3a-sense in Table 1 ... more In the version of this article initially published, the sequence of primer VH3a-sense in Table 1 incorrectly indicated a 'C' at position 12 instead of a 'G'. The error has been corrected in the HTML and PDF versions of the article.

Nature Protocols, 2014

In this protocol we describe the incorporation of bio-orthogonal amino acids as a versatile metho... more In this protocol we describe the incorporation of bio-orthogonal amino acids as a versatile method for visualizing and identifying de novo-synthesized proteins in the roundworm Caenorhabditis elegans. this protocol contains directions on implementing three complementary types of analysis: 'click chemistry' followed by western blotting, click chemistry followed by immunofluorescence, and isobaric tags for relative and absolute quantification (itraQ) quantitative mass spectrometry. the detailed instructions provided herein enable researchers to investigate the de novo proteome, an analysis that is complicated by the fact that protein molecules are chemically identical to each other, regardless of the timing of their synthesis. our protocol circumvents this limitation by identifying de novo-synthesized proteins via the incorporation of the chemically modifiable azidohomoalanine instead of the natural amino acid methionine in the nascent protein, followed by facilitating the visualization of the resulting labeled proteins in situ. It will therefore be an ideal tool for studying de novo protein synthesis in physiological and pathological processes including learning and memory. the protocol requires 10 d for worm growth, liquid culture and synchronization; 1-2 d for bio-orthogonal labeling; and, with regard to analysis, 3-4 d for western blotting, 5-6 d for immunofluorescence or ~3 weeks for mass spectrometry.

Vaccine, 2004

Group A streptococci (S. pyogenes) are responsible for pharyngitis, impetigo and several more ser... more Group A streptococci (S. pyogenes) are responsible for pharyngitis, impetigo and several more serious diseases. Emergence of toxic shock, and necrotizing fasciitis, associated with this pathogen over the past 10 years, has generated interest in development of a vaccine, which would prevent infections and potential serious complications. The highly conserved C5a peptidase that is expressed on the surface of group A streptococcus and other streptococcal species, associated with human infections, is a prime vaccine candidate. Here, we report construction of an inactive form of the peptidase and test its potential to induce protection in mice from intranasal challenge with either serotype M1 and M49 strains of streptococci. Mice were immunized by subcutaneous administration of recombinant proteins, mixed with Alum and monophosphoryl lipid A (MPL) adjuvants. Control mice were vaccinated with tetanus toxoid in the same adjuvants. Preparations of SCPA protein were highly immunogenic in mice. Antibody directed against protein from either group A (SCPAw) or group B (SCPBw) streptococci neutralized activity associated with both enzymes. Streptococci were cleared from the oral-nasal mucosa of mice immunized with vaccine protein more rapidly than those immunized with tetanus toxoid. Moreover, immunization with either protein enhanced clearance of group A streptococci from the lung. These results suggest that parenteral vaccination with SCPBw protein will provide protection against infection by either group A or B streptococci.

Toxicology in Vitro, 1989

The metabolism of the aromatic amine 1,3-diaminobenzcne (MPD) was studied/n vitro by use of the p... more The metabolism of the aromatic amine 1,3-diaminobenzcne (MPD) was studied/n vitro by use of the perfused rat liver, primary rat hepatocyte cultures and hepatic rat microsomes. The metabohtes formed were compared with urinary metabolites excreted by the rat /n vivo. Metabolites of p4C]MPD excreted by the perfused liver were found to be identical with urinary excreted metabolites/n vivo, thro~ of which were found to correlate with the N-acety!ated derivatives N,N'-diacetyl-l,3-diaminobenzene, N,N'-diacetyl-2,4-diaminophenol and N-acetyl-l,3-diaminobenzene. Also, the primary hgpatoc:yte cultures formed the metabolites found in the urine. However, several other metabolites, including some glucuronic acid conjugates, could be detected in the culture medium. In contrast to the peffused liver and the primary hepatocyte cultures, a reconstituted microsomal system was unable to form any of the metabolites formed by the other in vitro models and /n vivo. The results show that in addition to the metabolites that can be detected in the urine in vivo, several other derivatives, including glucuronic acid conjugates of MPD, are formed by the rat liver. The results suggest that primary rat hepatocyte cultures are the preferred model system in metabolic studies /n vitro and will constitute useful supplements to metabolic studies performed in the rat in vivo. 168 MATERIALS AND METHODS Chemicals 1,3-Diamino[14C]benzene (sp.act. 85.4/~Ci/mmol) was synthesized at Ris~, National Laboratory (Denmark). Waymouth medium 752/1, foetal calf serum and streptomycin-gentamycin were from GIBCO Europe Ltd, Paisley, UK and Amberlite XAD-2 resin was from BDH Chemicals Ltd, Poole, Dorset, UK. All enzymes, hormones and vitamins were purchased from Sigma Chemical Co., St Louis, MO, USA. Methanol and acetone (HPLC-grade) were from Rathburn Chemicals (UK). The liquid scintillation cocktail used was Opti-Fluor (Packard Instrument Co., Inc., Downers Grove, IL, USA). Animals Male Wistar rats (SPF) weighing approximately 250g were obtained from M~llegaard Breeding Centre (Denmark). The animals were kept individually in stainless-steel cages with free access to acidified water (citric acid, pH 3.5) and a pelleted diet (Chow 101,

Infection and Immunity, 1998

The ability of a serotype M1 strain of Streptococcus pyogenes to efficiently invade A549 human lu... more The ability of a serotype M1 strain of Streptococcus pyogenes to efficiently invade A549 human lung epithelial cells was previously shown to be dependent on bacterial exposure to human or bovine serum proteins or synthetic peptides containing the sequence RGD. In this study, stimulation by invasion agonists was determined to be dependent on expression of the streptococcal cell surface protein, M1. Fetal bovine serum (FBS), fibronectin (Fn), the extracellular matrix protein laminin (Lm), and RGD-containing peptides were tested for their abilities to promote epithelial cell invasion and adherence by isogenic M1 + and M1 − strains of S. pyogenes . In the absence of an agonist, invasion and adherence were comparable for the two bacterial strains. FBS, Fn, and Lm stimulated invasion of the M1 + strain as much as 70-fold but failed to significantly affect invasion by the M1 − mutant. Adherence of the wild-type strain was stimulated by these same agonists. Epithelial cell adherence by the ...

British Journal of Pharmacology, 2017

BACKGROUND AND PURPOSE PI3K-dependent activation of Rho kinase (ROCK) is necessary for agonist-in... more BACKGROUND AND PURPOSE PI3K-dependent activation of Rho kinase (ROCK) is necessary for agonist-induced human airway smooth muscle cell (HASMC) contraction, and inhibition of PI3K promotes bronchodilation of human small airways. The mechanisms driving agonist-mediated PI3K/ROCK axis activation, however, remain unclear. Given that G 12 family proteins activate ROCK pathways in other cell types, their role in M 3 muscarinic acetylcholine receptor-stimulated PI3K/ROCK activation and contraction was examined. EXPERIMENTAL APPROACH Gα 12 coupling was evaluated using co-immunoprecipitation and serum response element (SRE)-luciferase reporter assays. siRNA and pharmacological approaches, as well as overexpression of a regulator of G-protein signaling (RGS) proteins were applied in HASMCs. Phosphorylation levels of Akt, myosin phosphatase targeting subunit-1 (MYPT1), and myosin light chain-20 (MLC) were measured. Contraction and shortening were evaluated using magnetic twisting cytometry (MTC) and micro-pattern deformation, respectively. Human precision-cut lung slices (hPCLS) were utilized to evaluate bronchoconstriction. KEY RESULTS Knockdown of M 3 receptors or Gα 12 attenuated activation of Akt, MYPT1, and MLC phosphorylation. Gα 12 coimmunoprecipitated with M 3 receptors, and p115RhoGEF-RGS overexpression inhibited carbachol-mediated induction of SREluciferase reporter. p115RhoGEF-RGS overexpression inhibited carbachol-induced activation of Akt, HASMC contraction, and shortening. Moreover, inhibition of RhoA blunted activation of PI3K. Lastly, RhoA inhibitors induced dilation of hPCLS. CONCLUSIONS AND IMPLICATIONS Gα 12 plays a crucial role in HASMC contraction via RhoA-dependent activation of the PI3K/ROCK axis. Inhibition of RhoA activation induces bronchodilation in hPCLS, and targeting Gα 12 signaling may elucidate novel therapeutic targets in asthma. These findings provide alternative approaches to the clinical management of airway obstruction in asthma.

American Journal of Physiology-Lung Cellular and Molecular Physiology, 2017

Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality. Cigaret... more Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality. Cigarette smoke (CS) drives disease development and progression. The epithelial barrier is damaged by CS with increased monolayer permeability. However, the molecular changes that cause this barrier disruption and the interaction between adhesion proteins and the cytoskeleton are not well defined. We hypothesized that CS alters monolayer integrity by increasing cell contractility and decreasing cell adhesion in epithelia. Normal human airway epithelial cells and primary COPD epithelial cells were exposed to air or CS, and changes measured in protein levels. We measured the cortical tension of individual cells and the stiffness of cells in a monolayer. We confirmed that the changes in acute and subacute in vitro smoke exposure reflect protein changes seen in cell monolayers and tissue sections from COPD patients. Epithelial cells exposed to repetitive CS and those derived from COPD patients have...

Nature communications, Jul 26, 2017

A defining hallmark of primary and metastatic cancers is the migration and invasion of malignant ... more A defining hallmark of primary and metastatic cancers is the migration and invasion of malignant cells. These invasive properties involve altered dynamics of the cytoskeleton and one of its major structural components β-actin. Here we identify AIM1 (absent in melanoma 1) as an actin-binding protein that suppresses pro-invasive properties in benign prostate epithelium. Depletion of AIM1 in prostate epithelial cells increases cytoskeletal remodeling, intracellular traction forces, cell migration and invasion, and anchorage-independent growth. In addition, decreased AIM1 expression results in increased metastatic dissemination in vivo. AIM1 strongly associates with the actin cytoskeleton in prostate epithelial cells in normal tissues, but not in prostate cancers. In addition to a mislocalization of AIM1 from the actin cytoskeleton in invasive cancers, advanced prostate cancers often harbor AIM1 deletion and reduced expression. These findings implicate AIM1 as a key suppressor of invasi...

In this paper, the development and implementation of a direct-coupled building emulator for a bui... more In this paper, the development and implementation of a direct-coupled building emulator for a building energy management and control system (EMCS) is presented. The building emulator consists of a microcomputer and a computer model of an air-conditioning system implemented in a modular dynamic simulation software package for direct-coupling to an EMCS, without using analog-to-digital and digital-to-analog converters. The building emulator can be used to simulate in real time the behavior of the air-conditioning system under a given operating environment and subject to a given usage pattern. Software modules for data communication, graphical display, dynamic data exchange, and synchronization of simulation outputs with real time have been developed to achieve direct digital data transfer between the building emulator and a commercial EMCS. Based on the tests conducted, the validity of the building emulator has been established and the proportional-plus-integral control function of the EMCS assessed.link_to_subscribed_fulltex

The Royal Society of Chemistry eBooks, 2011

... 56. P. Aebischer and J. Ridet, Trends Neurosci., 2001, 24, 533. 57. EF Espejo, RJ Montoro, JA... more ... 56. P. Aebischer and J. Ridet, Trends Neurosci., 2001, 24, 533. 57. EF Espejo, RJ Montoro, JA Armengol and J. Lopez-Barneo, Neuron, 1998, 20, 197. 58. MR Luquin, RJ Montoro, J. Guillen, L. Saldise, R. Insausti, J. Del Rıo and J. Lopez-Barneo, Neuron, 1999, 22, 743. 59. ...

Advances in Meteorology, 2015

This work investigates the physical characteristics of raindrop size distribution (DSD) in an equ... more This work investigates the physical characteristics of raindrop size distribution (DSD) in an equatorial heavy rain region based on three years of disdrometer observations carried out at Universiti Teknologi Malaysia’s (UTM’s) campus in Kuala Lumpur, Malaysia. The natural characteristics of DSD are deduced, and the statistical results are found to be in accordance with the findings obtained from others disdrometer measurements. Moreover, the parameters of the Gamma distribution and the normalized Gamma model are also derived by means of method of moment (MoM) and maximum likelihood estimation (MLE). Their performances are subsequently validated using the rain rate estimation accuracy: the normalized Gamma model with the MLE-generated shape parameterµwas found to provide better accuracy in terms of long-term rainfall rate statistics, which reflects the peculiarities of the local climatology in this heavy rain region. These results not only offer a better understanding of the microphy...

International Journal of Electronics, 2015

This contribution presents a stochastic model useful for the generation of a long-term tropospher... more This contribution presents a stochastic model useful for the generation of a long-term tropospheric rain attenuation time series for Earth space or a terrestrial radio link in tropical and equatorial heavy rain regions based on the well-known Cox-Ingersoll-Ross model previously employed in research in the fields of finance and economics. This model assumes typical gamma distribution for rain attenuation in heavy rain climatic regions and utilises the temporal dynamic of precipitation collected in equatorial Johor, Malaysia. Different formations of survival probability are also discussed. Furthermore, the correlation between these probabilities and the Markov process is determined, and information on the variance and autocorrelation function of rain events with respect to the particular characteristics of precipitation in this area is presented. The proposed technique proved to preserve the peculiarities of precipitation for an equatorial region and reproduce fairly good statistics of the rain attenuation correlation function that could help to improve the prediction of dynamic characteristics of rain fade events.

2014 IEEE Asia-Pacific Conference on Applied Electromagnetics (APACE), 2014

This work evaluates the spatial features of the synthetic rain cell profile based on two years of... more This work evaluates the spatial features of the synthetic rain cell profile based on two years of real rain cells database extracted from weather radar observation located in Kluang, Johor, Malaysia. Single rain cells modeled by an analytical exponential and Gaussian profile are evaluated and investigated based on certain features of real rain cells such as maximum rain rate and root mean square rain rate inside a single rain cell. Preliminary results indicate the Gaussian profile with a shape factor k of 1 best represents real single-peaked rain structures in this particularly heavy rain area. However, the validity of results rely highly on the resolution limitation of the database used in this work, where the commercial operating meteorological radar consists of coarse quantization resolution of rain-rate, which might misinterpret the real rain cell profile at a lower rain rate. Nevertheless, this work still provides radio engineers with useful information for the design of wireless communication systems in this particular area (heavy rain region).

2014 International Symposium on Antennas and Propagation Conference Proceedings, 2014

Satellite communication systems operating at frequencies above 10 GHz are often subject to deep f... more Satellite communication systems operating at frequencies above 10 GHz are often subject to deep fades due to rain attenuation. One of the cost-effective countermeasures that can be used to counteract severe rain attenuation is time diversity. In this paper, performance of time diversity is investigated based on a one-year, Ku-band propagation measurement campaign carried out in heavy rain region. The results found show that the diversity gain increases as a function of time delay. The performance of time diversity is compared with prediction obtained by applying the Stratiform Convective-Synthetic Storm Technique (SC-SST) and a good agreement with measured statistics has been found.

2014 International Symposium on Antennas and Propagation Conference Proceedings, 2014

Advanced satellite communication or modern wireless systems operate at high frequencies will suff... more Advanced satellite communication or modern wireless systems operate at high frequencies will suffer from deep signal fades caused by rain particularly in equatorial region. Meteorological radar operates by MET department is one of the valuable resources to provide the peculiarities of the local precipitation information oriented to the analysis of radio propagation impairments. In this paper, the processing methodology and the interpretation procedure of operational weather radar data are presented from the perspective of such application. The applicability of the processed meteorological radar data is preliminary assessed against Stratiform Convective-Synthetic Storm Technique (SC-SST) in terms of first order rain attenuation statistics. The radar data simulated statistic is found to agree well with the one obtained through SC-SST. This procedure can be useful as a reference methodology for the employment of operational meteorological radar particularly focus on the propagation applications.

2014 XXXIth URSI General Assembly and Scientific Symposium (URSI GASS), 2014

This study is aimed to investigate the relationship between ground wind direction and the seasona... more This study is aimed to investigate the relationship between ground wind direction and the seasonal variation of rain attenuation based on one year of weather station data recorded in Universiti Teknologi Malaysia (UTM), Johor, Malaysia. Preliminary analysis of wind direction based on monsoon seasonal and their impact on rain field advection are carried out to clarify the characteristics of rain attenuation in monsoon season. It is found that rain attenuation is not only affected by the monsoon seasonal variation but it also depends on rain field advection which can be preliminary identified from the wind direction. Such information is useful for the system operators to apply appropriate site diversity techniques during heavy rain events to reduce the system outage in this particular equatorial region.

IEEE Sensors Journal, 2015

ABSTRACT

Nature Protocols, 2014

In the version of this article initially published, the sequence of primer VH3a-sense in Table 1 ... more In the version of this article initially published, the sequence of primer VH3a-sense in Table 1 incorrectly indicated a 'C' at position 12 instead of a 'G'. The error has been corrected in the HTML and PDF versions of the article.

Nature Protocols, 2014

In this protocol we describe the incorporation of bio-orthogonal amino acids as a versatile metho... more In this protocol we describe the incorporation of bio-orthogonal amino acids as a versatile method for visualizing and identifying de novo-synthesized proteins in the roundworm Caenorhabditis elegans. this protocol contains directions on implementing three complementary types of analysis: 'click chemistry' followed by western blotting, click chemistry followed by immunofluorescence, and isobaric tags for relative and absolute quantification (itraQ) quantitative mass spectrometry. the detailed instructions provided herein enable researchers to investigate the de novo proteome, an analysis that is complicated by the fact that protein molecules are chemically identical to each other, regardless of the timing of their synthesis. our protocol circumvents this limitation by identifying de novo-synthesized proteins via the incorporation of the chemically modifiable azidohomoalanine instead of the natural amino acid methionine in the nascent protein, followed by facilitating the visualization of the resulting labeled proteins in situ. It will therefore be an ideal tool for studying de novo protein synthesis in physiological and pathological processes including learning and memory. the protocol requires 10 d for worm growth, liquid culture and synchronization; 1-2 d for bio-orthogonal labeling; and, with regard to analysis, 3-4 d for western blotting, 5-6 d for immunofluorescence or ~3 weeks for mass spectrometry.

Vaccine, 2004

Group A streptococci (S. pyogenes) are responsible for pharyngitis, impetigo and several more ser... more Group A streptococci (S. pyogenes) are responsible for pharyngitis, impetigo and several more serious diseases. Emergence of toxic shock, and necrotizing fasciitis, associated with this pathogen over the past 10 years, has generated interest in development of a vaccine, which would prevent infections and potential serious complications. The highly conserved C5a peptidase that is expressed on the surface of group A streptococcus and other streptococcal species, associated with human infections, is a prime vaccine candidate. Here, we report construction of an inactive form of the peptidase and test its potential to induce protection in mice from intranasal challenge with either serotype M1 and M49 strains of streptococci. Mice were immunized by subcutaneous administration of recombinant proteins, mixed with Alum and monophosphoryl lipid A (MPL) adjuvants. Control mice were vaccinated with tetanus toxoid in the same adjuvants. Preparations of SCPA protein were highly immunogenic in mice. Antibody directed against protein from either group A (SCPAw) or group B (SCPBw) streptococci neutralized activity associated with both enzymes. Streptococci were cleared from the oral-nasal mucosa of mice immunized with vaccine protein more rapidly than those immunized with tetanus toxoid. Moreover, immunization with either protein enhanced clearance of group A streptococci from the lung. These results suggest that parenteral vaccination with SCPBw protein will provide protection against infection by either group A or B streptococci.

Toxicology in Vitro, 1989

The metabolism of the aromatic amine 1,3-diaminobenzcne (MPD) was studied/n vitro by use of the p... more The metabolism of the aromatic amine 1,3-diaminobenzcne (MPD) was studied/n vitro by use of the perfused rat liver, primary rat hepatocyte cultures and hepatic rat microsomes. The metabohtes formed were compared with urinary metabolites excreted by the rat /n vivo. Metabolites of p4C]MPD excreted by the perfused liver were found to be identical with urinary excreted metabolites/n vivo, thro~ of which were found to correlate with the N-acety!ated derivatives N,N'-diacetyl-l,3-diaminobenzene, N,N'-diacetyl-2,4-diaminophenol and N-acetyl-l,3-diaminobenzene. Also, the primary hgpatoc:yte cultures formed the metabolites found in the urine. However, several other metabolites, including some glucuronic acid conjugates, could be detected in the culture medium. In contrast to the peffused liver and the primary hepatocyte cultures, a reconstituted microsomal system was unable to form any of the metabolites formed by the other in vitro models and /n vivo. The results show that in addition to the metabolites that can be detected in the urine in vivo, several other derivatives, including glucuronic acid conjugates of MPD, are formed by the rat liver. The results suggest that primary rat hepatocyte cultures are the preferred model system in metabolic studies /n vitro and will constitute useful supplements to metabolic studies performed in the rat in vivo. 168 MATERIALS AND METHODS Chemicals 1,3-Diamino[14C]benzene (sp.act. 85.4/~Ci/mmol) was synthesized at Ris~, National Laboratory (Denmark). Waymouth medium 752/1, foetal calf serum and streptomycin-gentamycin were from GIBCO Europe Ltd, Paisley, UK and Amberlite XAD-2 resin was from BDH Chemicals Ltd, Poole, Dorset, UK. All enzymes, hormones and vitamins were purchased from Sigma Chemical Co., St Louis, MO, USA. Methanol and acetone (HPLC-grade) were from Rathburn Chemicals (UK). The liquid scintillation cocktail used was Opti-Fluor (Packard Instrument Co., Inc., Downers Grove, IL, USA). Animals Male Wistar rats (SPF) weighing approximately 250g were obtained from M~llegaard Breeding Centre (Denmark). The animals were kept individually in stainless-steel cages with free access to acidified water (citric acid, pH 3.5) and a pelleted diet (Chow 101,