MyMedR

Fulltext Electronic Characterization of Au/DNA/ITO Metal-Semiconductor-Metal Diode and Its Application as a Radiation Sensor

Al-Ta'ii HM, Periasamy V, Amin YM

PLoS One, 2016;11(1):e0145423.

PMID: 26799703 DOI: 10.1371/journal.pone.0145423

Deoxyribonucleic acid or DNA molecules expressed as double-stranded (DSS) negatively charged polymer plays a significant role in electronic states of metal/silicon semiconductor structures. Electrical parameters of an Au/DNA/ITO device prepared using self-assembly method was studied by using current-voltage (I-V) characteristic measurements under alpha bombardment at room temperature. The results were analyzed using conventional thermionic emission model, Cheung and Cheung's method and Norde's technique to estimate the barrier height, ideality factor, series resistance and Richardson constant of the Au/DNA/ITO structure. Besides demonstrating a strongly rectifying (diode) characteristic, it was also observed that orderly fluctuations occur in various electrical parameters of the Schottky structure. Increasing alpha radiation effectively influences the series resistance, while the barrier height, ideality factor and interface state density parameters respond linearly. Barrier height determined from I-V measurements were calculated at 0.7284 eV for non-radiated, increasing to about 0.7883 eV in 0.036 Gy showing an increase for all doses. We also demonstrate the hypersensitivity phenomena effect by studying the relationship between the series resistance for the three methods, the ideality factor and low-dose radiation. Based on the results, sensitive alpha particle detectors can be realized using Au/DNA/ITO Schottky junction sensor.

Fulltext Electronic Properties of DNA-Based Schottky Barrier Diodes in Response to Alpha Particles

Al-Ta'ii HM, Periasamy V, Amin YM

Sensors (Basel), 2015;15(5):11836-53.

PMID: 26007733 DOI: 10.3390/s150511836

Detection of nuclear radiation such as alpha particles has become an important field of research in recent history due to nuclear threats and accidents. In this context; deoxyribonucleic acid (DNA) acting as an organic semiconducting material could be utilized in a metal/semiconductor Schottky junction for detecting alpha particles. In this work we demonstrate for the first time the effect of alpha irradiation on an Al/DNA/p-Si/Al Schottky diode by investigating its current-voltage characteristics. The diodes were exposed for different periods (0-20 min) of irradiation. Various diode parameters such as ideality factor, barrier height, series resistance, Richardson constant and saturation current were then determined using conventional, Cheung and Cheung's and Norde methods. Generally, ideality factor or n values were observed to be greater than unity, which indicates the influence of some other current transport mechanism besides thermionic processes. Results indicated ideality factor variation between 9.97 and 9.57 for irradiation times between the ranges 0 to 20 min. Increase in the series resistance with increase in irradiation time was also observed when calculated using conventional and Cheung and Cheung's methods. These responses demonstrate that changes in the electrical characteristics of the metal-semiconductor-metal diode could be further utilized as sensing elements to detect alpha particles.

Nucleotide sequence and phylogenetic analysis of a segment of a highly virulent strain of infectious bursal disease virus

Chong LK, Omar AR, Yusoff K, Hair-Bejo M, Aini I

Acta Virol., 2001;45(4):217-26.

PMID: 11885928

The complete nucleotide sequences encoding precursor polyprotein (VP2-VP3-VP4) and VP5 of a highly virulent (hv) infectious bursal disease virus (IBDV), UPM97/61 was determined. Comparison of the deduced amino acid sequences with the published ones revealed 8 common amino acid substitutions, which were found only in the hv IBDV including the UPM97/61 strain. Three of the amino acid substitutions (222 Ala, 256 Ile and 294 Ile) were used as a marker for determining hv IBDV strains. The other five substitutions (685 Asn, 715 Ser, 751 Asp, 990 Val and 1005 Ala) were also conserved in hv IBDV strains isolated in various countries. UPM97/61 strain demonstrated also 8 unique amino acid substitutions of which 3 were in VP2, 4 in VP3 and 1 in VP4. There was 1 unique amino acid substitution in VP5 at position 19 (Asp-->Gly) not found in other strains. However, all the strains have a conserved 49 Arg. The amino acid sequence of UPM97/61 strain differed by 1.09% from the Japanese (OKYM) and Hong Kong (HK46) strains, and by 1.48% from the Israeli (IBDVKS) and European (UK661) strains. Hence, UPM97/61 is more closely related to the hv strains from Asia. However, phylogenetic analysis indicated that the origin of UPM97/61 might be the same as that of other hv strains isolated from other parts of the world.

Fulltext Markers of ventricular tachyarrythmias in patients with acromegaly

Mohamed AL, Yusoff K, Muttalif AR, Khalid BAk

Med J Malaysia, 1999 Sep;54(3):338-45.

PMID: 11045060

Sudden cardiac death is a known complication of acromegaly. Little is known of the exact mechanism leading to sudden cardiac death in these patients. Ventricular tachyarrhythmias may be an important cause. If this is so, clinical markers of ventricular tachyarrhythmias may be more common in this group of patients. The presence of these markers allow better risk stratification among acromegalic patients.

Heterogeneity of the CYP2D6 gene among Malays in Malaysia

Teh LK, Ismail R, Yusoff R, Hussein A, Isa MN, Rahman AR

J Clin Pharm Ther, 2001 Jun;26(3):205-11.

PMID: 11422605

Although Malays shared an origin with Chinese, their evolution saw substantial divergences. Phenotyping studies suggested that they differed in CYP2D6 polymorphism, with higher PM prevalence but lesser right-shift for debrisoquine MRs.

Chimeric Newcastle disease virus nucleocapsid with parts of viral hemagglutinin-neuraminidase and fusion proteins

Rabu A, Tan WS, Kho CL, Omar AR, Yusoff K

Acta Virol., 2002;46(4):211-7.

PMID: 12693857

The nucleocapsid (NP) protein of Newcastle disease virus (NDV) self-assembled in Escherichia coli as ring-like and herringbone-like particles. Several chimeric NP proteins were constructed in which the antigenic regions of the hemagglutinin-neuraminidase (HN) and fusion (F) proteins of NDV, myc epitope, and six histidines (a hexa-His tag) were linked to the C-terminus of the NP monomer. These chimeric proteins were expressed efficiently in soluble form in E. coli as detected by Western blot analysis. Electron microscopy of the purified products revealed that they self-assembled into ring-like particles. These chimeric particles exhibited antigenicity of the myc epitope, suggesting that the foreign sequences were exposed on the surface of the particles. Chickens inoculated with the chimeric particles mounted an immune response against NDV, suggesting the possibility of use of the ring-like particle as a carrier of immunogens in subunit vaccines and immunological reagents.

Characterisation and molecular cloning of an erythromycin resistance plasmid of Lactococcus lactis isolated from chicken cecum

Raha AR, Ross E, Yusoff K, Manap MY, Ideris A

J. Biochem. Mol. Biol. Biophys., 2002 Feb;6(1):7-11.

PMID: 12186776

An erythromycin resistance plasmid, pAJ01 was isolated from Loctococcus lactis isolate C5 that was isolated from a healthy two-week-old chicken cecum. A 4 kb plasmid was transformed into plasmidless L. lactis MG1363 before a restriction endonuclease map was constructed. It was then fused with pUC19 to form pAJ02, which can replicate in Escherichia coli XLI-Blue as well as L. lactis MG1363. The plasmid was stably maintained in Lactococcus for more than 100 generations.

Nucleotide sequence of the haemagglutinin-neuraminidase (HN) gene of a Malaysian heat resistant viscerotropic-velogenic Newcastle disease virus (NDV) strain AF2240

Tan WS, Lau CH, Ng BK, Ibrahim AL, Yusoff K

DNA Seq., 1995;6(1):47-50.

PMID: 8746461

The nucleotide sequence of the haemagglutinin-neuraminidase (HN) gene of Newcastle disease virus (NDV) viscerotropic-velogenic strain AF2240 was determined by direct RNA sequencing and by sequencing RT-PCR products. It encodes a single open reading frame of 581 amino acids with a calculated Mr of 63.8 kDa. The predicted sequence contains five asparagine glycosylation sites. Comparison of the AF2240 HN protein sequence with 13 other previously published sequences showed 88% homology. This HN protein is unique because it lacked the Arg 403 residue which is present in all of the other strains and cannot be grouped under the proposed three size classes of HN proteins in NDV.

Detection of Newcastle disease virus using a SYBR Green I real time polymerase chain reaction

Tan SW, Omar AR, Aini I, Yusoff K, Tan WS

Acta Virol., 2004;48(1):23-8.

PMID: 15230471

A two-step SYBR Green I real time polymerase chain reaction (PCR, real time PCR) for the detection of Newcastle disease virus (NDV) was developed. A melting curve analysis was performed to distinguish specific from non-specific products and primer dimers. Regardless of different virus pathotypes the melting temperature (Tm) ranged from 86 degrees C to 87 degrees C. The sensitivity of the real time PCR was compared with the reverse transcription (RT)-nested PCR enzyme-linked immunosorbent assay (ELISA, RT-nested PCR ELISA). Whereas the detection limit of the real time PCR was 10 pg DNA, the RT-nested PCR ELISA and conventional PCR could only detect up to 1 ng and 10 ng DNA, respectively. Thus the real time PCR offers a sensitive, rapid and convenient method for screening large number of NDV specimens.

Fulltext Measurement of intima-media thickness of common carotid arteries using ultrasound in patients with familial and non-familial hypercholesterolaemia and correlation of intima-media thickness to obesity

Nafikudin M, Nawawi H, Muid S, Annuar R, Yusoff K, Khalid BAK

Med J Malaysia, 2003 Dec;58(5):647-52.

PMID: 15190648

Ultrasonographic measurements of the intima-media thickness (IMT) of common carotid arteries (CCA) were taken in 50 patients with familial hypercholesterolaemia (FH) and 57 patients with non-familial hypercholesterolemia (NFH). The lipid profile, body mass index (BMI) and waist-hip ratio (WHR) of each patient were recorded. In FH patients, the IMT was significantly higher in overweight and elevated WHR subgroups compared to the normal with significant correlations between BMI and WHR to the IMT. In NFH patients, the IMT was significantly higher in the elevated WHR compared to the normal subgroup but the correlations between either BMI or WHR to IMT were insignificant. These suggest that the environmentally modified anthropometric indices may have an effect on atherosclerosis in genetically determined hypercholesterolaemia in FH patients.

Regions on nucleocapsid protein of Newcastle disease virus that interact with its phosphoprotein

Kho CL, Tan WS, Tey BT, Yusoff K

Arch Virol, 2004 May;149(5):997-1005.

PMID: 15098113 DOI: 10.1007/s00705-003-0273-8

The nucleocapsid (NP) and phospho-(P) proteins of paramyxoviruses are involved in transcription and replication of the viral genome. An in vitro protein binding assay was used to investigate the regions on NP protein that interact with the P protein of Newcastle disease virus (NDV). Truncated NP mutants were first immobilised on a solid phase and then interacted with radio-labelled [(35)S]-P protein synthesised in rabbit reticulocyte. The interaction affinity was quantitated by measuring the radioactivity that was retained on the solid phase. Using this approach, a highly interactive region was identified to be resided at the first 25 amino acids of NP N-terminus. The interaction between these two proteins remained strong even with the removal of 114 amino acids from the C-terminal end of NP. However, it is possible that the 49 amino acids at the C-terminal end might have another contact region for P protein, which is not as critical as the N-terminal end. The interaction regions mapped in this study are significantly different from the other two paramyxoviruses: Sendai and measles viruses in which the C-termini of their NP proteins play an important role in binding to the P.

Cell surface display system for Lactococcus lactis: a novel development for oral vaccine

Raha AR, Varma NR, Yusoff K, Ross E, Foo HL

Appl Microbiol Biotechnol, 2005 Jul;68(1):75-81.

PMID: 15635459

The food-grade Lactococcus lactis is a potential vector to be used as a live vehicle for the delivery of heterologous proteins for vaccine and pharmaceutical purposes. We constructed a plasmid vector pSVac that harbors a 255-bp single-repeat sequence of the cell wall-binding protein region of the AcmA protein. The recombinant plasmid was transformed into Escherichia coli and expression of the gene fragment was driven by the T7 promoter of the plasmid. SDS-PAGE showed the presence of the putative AcmA' fragment and this was confirmed by Western blot analysis. The protein was isolated and purified using a His-tag affinity column. When mixed with a culture of L. lactis MG1363, ELISA and immunofluorescence assays showed that the cell wall-binding fragment was anchored onto the outer surface of the bacteria. This indicated that the AcmA' repeat unit retained the active site for binding onto the cell wall surface of the L. lactis cells. Stability assays showed that the fusion proteins (AcmA/A1, AcmA/A3) were stably docked onto the surface for at least 5 days. The AcmA' fragment was also shown to be able to strongly bind onto the cell surface of naturally occurring lactococcal strains and Lactobacillus and, with less strength, the cell surface of Bacillus sphericus. The new system designed for cell surface display of recombinant proteins on L. lactis was evaluated for the expression and display of A1 and A3 regions of the VP1 protein of enterovirus 71 (EV71). The A1 and A3 regions of the VP1 protein of EV71 were cloned upstream to the cell wall-binding domains of AcmA protein and successfully expressed as AcmA/A1 and AcmA/A3. Whole-cell ELISA showed the successful display of VP1 protein epitopes of EV71 on the surface of L. lactis. The success of the anchoring system developed in this study for docking the A1 and A3 epitopes of VP1 onto the surface of L. lactis cells opens up the possibilities of peptide and protein display for not only Lactococcus but also for other gram-positive bacteria. This novel way of displaying epitopes on the cell surface of L. lactis and other related organisms should be very useful in the delivery of vaccines and other useful proteins.

Prevalence of optimal cardiovascular screening activities and associated factors among apparently healthy school teachers in Kota Bharu, Kelantan

Noraza RA, Norhayati NM, Rosediani M, Harmy YM

J Taibah Univ Med Sci, 2018 Apr;13(2):188-194.

PMID: 31435322 DOI: 10.1016/j.jtumed.2017.10.005

Objectives: This study aimed to determine the prevalence of optimal cardiovascular disease (CVD) screening activities and the associated factors among apparently healthy school teachers.

Methods: A cross-sectional analytical observational study was conducted among 380 secondary school teachers in Kelantan, Malaysia. A self-administered questionnaire addressing sociodemographic data and factors influencing CVD screening activities was administered. Descriptive analysis, simple and multiple logistic regression analyses were performed.

Results: A total of 348 teachers responded to the questionnaire, with a response rate of 91.6%. The prevalence of optimal CVD screening activities was 29.3% (95% CI: 24.52, 34.08). Age, knowledge of CVD screening, family history of CVD and availability of health facilities were significantly linked to CVD screening.

Conclusion: The prevalence of optimal screening activities was low. A great majority of the factors contributing to optimal screening were modifiable. Health care providers should widely implement global health-oriented rather than disease-orientated assessment in their daily practice.

Genetic characterization of Perna viridis L. in peninsular Malaysia using microsatellite markers

Ong CC, Yusoff K, Yap CK, Tan SG

J Genet, 2009 Aug;88(2):153-63.

PMID: 19700853

A total of 19 polymorphic microsatellite loci were used to analyse levels of genetic variation for 10 populations of Perna viridis L. collected from all over peninsular Malaysia. The populations involved in this study included Pulau Aman in Penang, Tanjung Rhu in Kedah, Bagan Tiang in Perak, Pulau Ketam in Selangor, Muar, Parit Jawa, Pantai Lido and Kampung Pasir Puteh in Johore, and Kuala Pontian and Nenasi in Pahang state. The number of alleles per locus ranged from two to seven, with an average of 3.1. Heterozygote deficiencies were observed across all the 10 populations. Characterization of the populations revealed that local populations of P. viridis in peninsular Malaysia were genetically similar enough to be used as a biomonitoring agent for heavy metal contamination in the Straits of Malacca. Cluster analysis grouped the P. viridis populations according to their geographical distributions with the exception of Parit Jawa. The analysis also revealed that P. viridis from the northern parts of peninsular Malaysia were found to be the most distant populations among the populations of mussels investigated and P. viridis from the eastern part of peninsular Malaysia were closer to the central and southern populations than to the northern populations.

Sequence of the haemagglutinin-neuraminidase gene of the Newcastle disease virus oral vaccine strain V4(UPM)

Yusoff K, Tan WS, Lau CH, Ng BK, Ibrahim AL

Avian Pathol, 1996 Dec;25(4):837-44.

PMID: 18645902

The nucleotide sequence of the haemagglutinin-neuraminidase (HN) glycoprotein gene of Newcastle disease virus (NDV) variant strain V4(UPM) was determined by direct genomic RNA sequencing and confirmed by cycle sequencing. The gene comprises 1996 nucleotides encoding a 615 amino acid protein of size 67.4 kDa. The nucleotide and amino acid sequences of this strain were compared with those of the parent strain V4(QUE). There are 16 nucleotide substitutions on V4(UPM), eight of which are silent mutations and another eliminated a potential Asn-linked glycosylation site in V4(UPM). In addition, an Arg (403) residue was shown to be absent in the variant strain. This deletion is thought to be significant because of its location in a highly conserved region of the HN protein.

Expression of a thermostable xylanase gene from Bacillus coagulans ST-6 in Lactococcus lactis

Raha AR, Chang LY, Sipat A, Yusoff K, Haryanti T

Lett Appl Microbiol, 2006 Mar;42(3):210-4.

PMID: 16478506

The aim of the study is to evaluate whether xylanase can be used as a potential reporter gene for cloning and expression studies in Lactococcus.

Fulltext Surface display of respiratory syncytial virus glycoproteins in Lactococcus lactis NZ9000

Lim SH, Jahanshiri F, Rahim RA, Sekawi Z, Yusoff K

Lett Appl Microbiol, 2010 Dec;51(6):658-64.

PMID: 20973806 DOI: 10.1111/j.1472-765X.2010.02950.x

A system for displaying heterologous respiratory syncytial virus (RSV) glycoproteins on the surface of Lactococcus lactis NZ9000 was developed.

The genetic structure of Oreochromis spp. (Tilapia) populations in Malaysia as revealed by microsatellite DNA analysis

Bhassu S, Yusoff K, Panandam JM, Embong WK, Oyyan S, Tan SG

Biochem Genet, 2004 Aug;42(7-8):217-29.

PMID: 15487586

The genetic make-up of five populations of Oreochromis spp. was examined by microsatellite analysis. Eleven polymorphic microsatellite loci showed significant departures from the Hardy-Weinberg equilibrium. The mean heterozygosity ranged from 0.6280 to 0.7040 for each population. The genetic distance values showed a clear separation between O. niloticus and O. mossambicus. The differentiation of the O. niloticus populations was then tested with various genetic measures, which are based on both the Infinite Allele and the Stepwise Mutation models. All these measures grouped the populations similarly.

Identification and characterization of Malaysian river catfish, Mystus nemurus (C&V): RAPD and AFLP analysis

Chong LK, Tan SG, Yusoff K, Siraj SS

Biochem Genet, 2000 Apr;38(3-4):63-76.

PMID: 11100266

This work represents the first application of the amplified fragment length polymorphism (AFLP) technique and the random amplified polymorphic DNA (RAPD) technique in the study of genetic variation within and among five geographical populations of M. nemurus. Four AFLP primer combinations and nine RAPD primers detected a total of 158 and 42 polymorphic markers, respectively. The results of AFLP and RAPD analysis provide similar conclusions as far as the population clustering analysis is concerned. The Sarawak population, which is located on Borneo Island, clustered by itself and was thus isolated from the rest of the populations located in Peninsular Malaysia. Both marker systems revealed high genetic variability within the Universiti Putra Malaysia (UPM) and Sarawak populations. Three subgroups each from the Kedah, Perak, and Sarawak populations were detected by AFLP but not by RAPD. Unique AFLP fingerprints were also observed in some unusual genotypes sampled in Sarawak. This indicates that AFLP may be a more efficient marker system than RAPD for identifying genotypes within populations.

Cardiogenic shock with complete heart block secondary to dengue myocarditis requiring temporary pacing

Mohd Ramdzan MY, Mohd Khalid KF, Che Mood M

Cardiol Young, 2021 Aug 02.

PMID: 34334145 DOI: 10.1017/S1047951121003152

This case illustrates acute myocarditis with complete heart block in a 13-year-old teenager as a rare complication of acute dengue illness. He required urgent temporary pacing with inotropic support and antifailure medications. Complete heart block in dengue myocarditis is an acute but reversible condition. A similar presentation in a dengue-endemic country or with a history of travelling to tropical countries warrants a suspicion of dengue infection.

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