MyMedR

Fulltext Streptococcus Constellatus Spondylodiscitis in a Teenager: A Case Report

Lim SW, Lim HY, Kannaiah T, Zuki Z

Malays Orthop J, 2017 Nov;11(3):50-52.

PMID: 29326768 MyJurnal DOI: 10.5704/MOJ.1711.004

Streptococcus constellatus is an extremely rare cause of pyogenic spondylodiscitis. Literature search yielded only one case report in an elderly 72 years old man with spontaneous T10-T11 S. constellatus spondylodiscitis. It is virtually unheard of in young teenage. We report the case of a 14 years old male teenager who presented with worsening low back pain for one year with no neurological deficit. Imaging studies were consistent with features of L4-L5 spondylodiscitis. CT guided biopsy grew a pure culture of streptococcus constellatus sensitive to penicillin and erythromycin. He showed full recovery with six weeks of intravenous antibiotics. Due to the insidious onset, this case highlight the importance of high clinical suspicion and early diagnosis, with image guided biopsy followed by treatment with appropriate intravenous antibiotics to enable full recovery without further neurological deterioration.

Fulltext Ventilatory function in Malay office workers in Malaysia

Che' Man AB, Lim HH

Singapore Med J, 1983 Jun;24(3):135-9.

PMID: 6635675

A study was carried out to determine ventilatory capacity (Forced Expiratory Volume or FEV1 and Forced Vital Capacity or FVC) in apparently normal Malay office workers in Malaysia. The subjects, 78 males and 113 females, were interviewed using a standardized questionnaire to exclude those with symptoms or past history of cardiopulmonary disease. Measurements of age, height, weight, FEV, and FVC were made on each subject; the FEV, and FVC were measured using Vitalograph spirometers. The mean FEV, and FVC for males were 3.35 litres and 3.76 Iitres, respectively. For females, the mean FEV, and FVC were 3.46 and 2.72 Iitres, respectively. Height was positively correlated with FEV, and FVC (p

Horseradish peroxidase-labeled silver/reduced graphene oxide thin film-modified screen-printed electrode for detection of carcinoembryonic antigen

Lee SX, Lim HN, Ibrahim I, Jamil A, Pandikumar A, Huang NM

Biosens Bioelectron, 2017 Mar 15;89(Pt 1):673-680.

PMID: 26718548 DOI: 10.1016/j.bios.2015.12.030

In this study, a disposable and simple electrochemical immunosensor was fabricated for the detection of carcinoembryonic antigen. In this method, silver nanoparticles (AgNPs) were mixed with reduced graphene oxide (rGO) to modify the surface of screen-printed carbon electrode (SPE). Initially, AgNPs-rGO modified-SPEs were fabricated by using simple electrochemical deposition method. Then the carcinoembryonic antigen (CEA) was immobilized between the primary antibody and horseradish peroxidase (HRP)-conjugated secondary antibody onto AgNPs-rGO modified-SPEs to fabricate a sandwich-type electrochemical immunosensor. The proposed method could detect the CEA with a linear range of 0.05-0.50µgmL-1 and a detection limit down to 0.035µgmL-1 as compared to its non-sandwich counterpart, which yielded a linear range of 0.05-0.40µgmL-1, with a detection limit of 0.042µgmL-1. The immunosensor showed good performance in the detection of carcinoembryonic antigen, exhibiting a simple, rapid and low-cost. The immunosensor showed a higher sensitivity than an enzymeless sensor.

Utilization of reduced graphene oxide/cadmium sulfide-modified carbon cloth for visible-light-prompt photoelectrochemical sensor for copper (II) ions

Foo CY, Lim HN, Pandikumar A, Huang NM, Ng YH

J Hazard Mater, 2016 Mar 5;304:400-8.

PMID: 26595899 DOI: 10.1016/j.jhazmat.2015.11.004

A newly developed CdS/rGO/CC electrode was prepared based on a flexible carbon cloth (CC) substrate with cadmium sulfide (CdS) nanoparticles and reduced graphene oxide (rGO). The CdS was synthesized using an aerosol-assisted chemical vapor deposition (AACVD) method, and the graphene oxide was thermally reduced on the modified electrode surface. The existence of rGO in the CdS-modified electrode increased the photocurrent intensity of the CdS/rGO/CC-modified electrode by three orders of magnitude, compared to that of the CdS/ITO electrode and two orders of magnitude higher than the CdS/CC electrode. A new visible-light-prompt photoelectrochemical sensor was developed based on the competitive binding reaction of Cu(2+) and CdS on the electrode surface. The results showed that the effect of the Cu(2+) on the photocurrent response was concentration-dependent over the linear ranges of 0.1-1.0 μM and 1.0-40.0 μM with a detection limit of 0.05 μM. The results of a selectivity test showed that this modified electrode has a high response toward Cu(2+) compared to other heavy metal ions. The proposed CdS/rGO/CC electrode provided a significantly high potential current compared to other reported values, and could be a practical tool for the fast, sensitive, and selective determination of Cu(2+).

Fabrication of graphene/gold-modified screen-printed electrode for detection of carcinoembryonic antigen

Chan KF, Lim HN, Shams N, Jayabal S, Pandikumar A, Huang NM

Mater Sci Eng C Mater Biol Appl, 2016 Jan 1;58:666-74.

PMID: 26478358 DOI: 10.1016/j.msec.2015.09.010

Immunosensors based on gold nanoparticles and reduced graphene oxide (AuNPs/rGO)-modified screen-printed electrodes (SPEs) were successfully synthesized using an electrochemical deposition method. The modified SPEs were characterized using a field emission scanning electron microscope (FESEM) and Raman spectroscopy to analyze the morphology and composition of AuNPs and rGO. Both the FESEM and Raman spectroscopy revealed that the AuNPs were successfully anchored on the thin film of rGO deposited on the surface of the SPEs. Characterization with a ferri-ferrocyanide couple [Fe(CN)6(3-/4-)] showed that the electron transfer kinetic between the analyte and electrode was enhanced after the modification with the AuNPs/rGO composite on the electrode surface, in addition to increasing the effective surface area of the electrode. The modified SPE was immobilized with a sandwich type immunosensor to mimic the ELISA (enzyme-linked immunosorbent assay) immunoassay. The modified SPE that was fortified with the sandwich type immunosensor exhibited double electrochemical responses in the detection of carcinoembryonic antigen (CEA), with linear ranges of 0.5-50 ng/mL and 250-2000 ng/mL and limits of detection of 0.28 ng/mL and 181.5 ng/mL, respectively.

Report of a freshwater hydrobiid snail from Pahang, Malaysia: a possible host for schistosomes infecting man

Greer GJ, Lim HK, Ow-Yang CK

Southeast Asian J. Trop. Med. Public Health, 1980 Mar;11(1):146-7.

PMID: 7403949

Blood cadmium levels in Malaysian pregnant women

Lim HH, Ong CN, Domala Z, Phoon WO

Southeast Asian J. Trop. Med. Public Health, 1983 Sep;14(3):394-8.

PMID: 6658508

Blood cadmium levels in Malaysian pregnant women were determined. There was no significant urban-rural difference in mean blood cadmium levels.

Blood lead levels in Malaysian urban and rural pregnant women

Lim HH, Ong CN, Domala Z, Phoon WO, Khoo HE

Public Health, 1985 Jan;99(1):23-9.

PMID: 3991872

Discovery of a site of transmission and hosts of a Schistosoma japonicum-like schistosome in Peninsular Malaysia

Greer GJ, Ow-Yang CK, Singh KI, Lim HK

Trans R Soc Trop Med Hyg, 1980;74(3):425.

PMID: 7434446

Preliminary report on new cercariae from Bellamya and Pila snails in Peninsular Malaysia

Lim HK, Colley FC, Ow-Yang CK

Southeast Asian J. Trop. Med. Public Health, 1974 Sep;5(3):458-9.

PMID: 4432110

Fulltext Author Correction: Electrochemical Performance of Supercapacitor with Stacked Copper Foils Coated with Graphene Nanoplatelets

Chiam SL, Lim HN, Hafiz SM, Pandikumar A, Huang NM

Sci Rep, 2018 Jul 12;8(1):10830.

PMID: 29997395 DOI: 10.1038/s41598-018-28897-7

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

Ultrasonic synthesis of CeO2@organic dye nanohybrid: Environmentally benign rabid electrochemical sensing platform for carcinogenic pollutant in water samples

Gowthaman NSK, Ngee Lim H, Balakumar V, Shankar S

Ultrason Sonochem, 2020 Mar;61:104828.

PMID: 31670250 DOI: 10.1016/j.ultsonch.2019.104828

A novel organic-inorganic nile-blue - CeO2 (CeO2/NB) nanohybrid has been synthesized by environmentally benign ultrasonic irradiation method for the selective determination of the environmental pollutant, carcinogenic hydrazine (HZ) in environmental water samples. Hydrophobic dyes have generally been as redox mediators in electrochemical sensors fabrication due to strong electron transfer capacity and they would allow the oxidation and reduction of the analytes at lower potentials. The CeO2 nanoparticles were initially synthesized by the ultrasonic irradiation of Ce(NO3)2, NH4OH and ethylene glycol mixture for 6 h using probe sonicator (20 kHz, 100 W) followed by calcination. The organic-dye NB was then added and ultrasonicated further 30 min for the formation of CeO2/NB nanohybrid material. Various spectroscopic and microscopic tools such as UV-vis and FT-IR spectroscopy, XRD, SEM and high-solution TEM and surface analysis tool Brunauer-Emmett-Teller (BET) confirm the formation of the nanohybrid. HR-TEM images showed the well-covered CeO2 on NB molecules and the average size of the nanohybrid is ~35 nm. For the fabrication of environmental pollutant electrochemical sensor, the prepared CeO2/NB nanohybrid was drop-casted on the electrode surface and utilized for the determination of HZ. The nanohybrid modified electrode exhibits higher electrocatalytic activity by showing enhanced oxidation current and less positive potential shift towards HZ oxidation than the bare and individual CeO2 and NB modified electrodes. The fabricated sensor with excellent reproducibility, repeatability, long-term storage stability and cyclic stability exhibited the sensational sensitivity (484.86 µA mM-1 cm-2) and specificity in the presence of 50-fold possible interfering agents with the lowest limit of detection of 57 nM (S/N = 3) against HZ. Utilization of the present sensor in environmental samples with excellent recovery proves it practicability in the determination of HZ in real-time application.

Fulltext Electrochemical Performance of Supercapacitor with Stacked Copper Foils Coated with Graphene Nanoplatelets

Chiam SL, Lim HN, Hafiz SM, Pandikumar A, Huang NM

Sci Rep, 2018 02 15;8(1):3093.

PMID: 29449631 DOI: 10.1038/s41598-018-21572-x

The energy density of conventional supercapacitors is in the range of 6-10 Wh kg-1, which has restricted them from many applications that require devices with long durations. Herein, we report a method for enhancing the energy density of a device through the parallel stacking of five copper foils coated on each side with graphene nanoplatelets. Microporous papers immersed in 2 M aqueous sodium sulphate were used as separators. With a low contact resistance of 0.05 Ω, the supercapacitor yielded an optimum specific energy density and a specific power density of 24.64 Wh kg-1 and 402 W kg-1 at 0.8 V, respectively. The working potential was increased to 2.4 V when three of the supercapacitors were connected in series, forming a tandem device. Its potential for real applications was manifested by the ability to light up a light-emitting diode for 40 s after charging for 60 s.

Multiple regression analysis in modeling of columnar ozone in Peninsular Malaysia

Tan KC, Lim HS, Mat Jafri MZ

Environ Sci Pollut Res Int, 2014 Jun;21(12):7567-77.

PMID: 24599658 DOI: 10.1007/s11356-014-2697-y

This study aimed to predict monthly columnar ozone (O3) in Peninsular Malaysia by using data on the concentration of environmental pollutants. Data (2003-2008) on five atmospheric pollutant gases (CO2, O3, CH4, NO2, and H2O vapor) retrieved from the satellite Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) were employed to develop a model that predicts columnar ozone through multiple linear regression. In the entire period, the pollutants were highly correlated (R = 0.811 for the southwest monsoon, R = 0.803 for the northeast monsoon) with predicted columnar ozone. The results of the validation of columnar ozone with column ozone from SCIAMACHY showed a high correlation coefficient (R = 0.752-0.802), indicating the model's accuracy and efficiency. Statistical analysis was utilized to determine the effects of each atmospheric pollutant on columnar ozone. A model that can retrieve columnar ozone in Peninsular Malaysia was developed to provide air quality information. These results are encouraging and accurate and can be used in early warning of the population to comply with air quality standards.

A review of zeolitic imidazolate frameworks (ZIFs) as electrochemical sensors for important small biomolecules in human body fluids

Feng Z, Lim HN, Ibrahim I, Gowthaman NSK

J Mater Chem B, 2023 Oct 06;11(38):9099-9127.

PMID: 37650588 DOI: 10.1039/d3tb01221b

Small biomolecules play a critical role in the fundamental processes that sustain life and are essential for the proper functioning of the human body. The detection of small biomolecules has garnered significant interest in various fields, including disease diagnosis and medicine. Electrochemical techniques are commonly employed in the detection of critical biomolecules through the principle of redox reactions. It is also a very convenient, cheap, simple, fast, and accurate measurement method in analytical chemistry. Zeolitic imidazolate frameworks (ZIFs) are a unique type of metal-organic framework (MOF) composed of porous crystals with extended three-dimensional structures. These frameworks are made up of metal ions and imidazolate linkers, which form a highly porous and stable structure. In addition to their many advantages in other applications, ZIFs have emerged as promising candidates for electrochemical sensors. Their large surface area, pore diameter, and stability make them ideal for use in sensing applications, particularly in the detection of small molecules and ions. This review summarizes the critical role of small biomolecules in the human body, the standard features of electrochemical analysis, and the utilization of various types of ZIF materials (including carbon composites, metal-based composites, ZIF polymer materials, and ZIF-derived materials) for the detection of important small biomolecules in human body fluids. Lastly, we provide an overview of the current status, challenges, and future outlook for research on ZIF materials.

Fulltext Fabrication and characterization of graphene hydrogel via hydrothermal approach as a scaffold for preliminary study of cell growth

Lim HN, Huang NM, Lim SS, Harrison I, Chia CH

Int J Nanomedicine, 2011;6:1817-23.

PMID: 21931479 DOI: 10.2147/IJN.S23392

BACKGROUND: Three-dimensional assembly of graphene hydrogel is rapidly attracting the interest of researchers because of its wide range of applications in energy storage, electronics, electrochemistry, and waste water treatment. Information on the use of graphene hydrogel for biological purposes is lacking, so we conducted a preliminary study to determine the suitability of graphene hydrogel as a substrate for cell growth, which could potentially be used as building blocks for biomolecules and tissue engineering applications.

METHODS: A three-dimensional structure of graphene hydrogel was prepared via a simple hydrothermal method using two-dimensional large-area graphene oxide nanosheets as a precursor.

RESULTS: The concentration and lateral size of the graphene oxide nanosheets influenced the structure of the hydrogel. With larger-area graphene oxide nanosheets, the graphene hydrogel could be formed at a lower concentration. X-ray diffraction patterns revealed that the oxide functional groups on the graphene oxide nanosheets were reduced after hydrothermal treatment. The three-dimensional graphene hydrogel matrix was used as a scaffold for proliferation of a MG63 cell line.

CONCLUSION: Guided filopodia protrusions of MG63 on the hydrogel were observed on the third day of cell culture, demonstrating compatibility of the graphene hydrogel structure for bioapplications.

Fulltext Application of polypyrrole multi-walled carbon nanotube composite layer for detection of mercury, lead and iron ions using surface plasmon resonance technique

Sadrolhosseini AR, Noor AS, Bahrami A, Lim HN, Talib ZA, Mahdi MA

PLoS One, 2014;9(4):e93962.

PMID: 24733263 DOI: 10.1371/journal.pone.0093962

Polypyrrole multi-walled carbon nanotube composite layers were used to modify the gold layer to measure heavy metal ions using the surface plasmon resonance technique. The new sensor was fabricated to detect trace amounts of mercury (Hg), lead (Pb), and iron (Fe) ions. In the present research, the sensitivity of a polypyrrole multi-walled carbon nanotube composite layer and a polypyrrole layer were compared. The application of polypyrrole multi-walled carbon nanotubes enhanced the sensitivity and accuracy of the sensor for detecting ions in an aqueous solution due to the binding of mercury, lead, and iron ions to the sensing layer. The Hg ion bonded to the sensing layer more strongly than did the Pb and Fe ions. The limitation of the sensor was calculated to be about 0.1 ppm, which produced an angle shift in the region of 0.3° to 0.6°.

Fulltext Simple room-temperature preparation of high-yield large-area graphene oxide

Huang NM, Lim HN, Chia CH, Yarmo MA, Muhamad MR

Int J Nanomedicine, 2011;6:3443-8.

PMID: 22267928 DOI: 10.2147/IJN.S26812

Graphene has attracted much attention from researchers due to its interesting mechanical, electrochemical, and electronic properties. It has many potential applications such as polymer filler, sensor, energy conversion, and energy storage devices. Graphene-based nanocomposites are under an intense spotlight amongst researchers. A large amount of graphene is required for preparation of such samples. Lately, graphene-based materials have been the target for fundamental life science investigations. Despite graphene being a much sought-after raw material, the drawbacks in the preparation of graphene are that it is a challenge amongst researchers to produce this material in a scalable quantity and that there is a concern about its safety. Thus, a simple and efficient method for the preparation of graphene oxide (GO) is greatly desired to address these problems. In this work, one-pot chemical oxidation of graphite was carried out at room temperature for the preparation of large-area GO with ~100% conversion. This high-conversion preparation of large-area GO was achieved using a simplified Hummer's method from large graphite flakes (an average flake size of 500 μm). It was found that a high degree of oxidation of graphite could be realized by stirring graphite in a mixture of acids and potassium permanganate, resulting in GO with large lateral dimension and area, which could reach up to 120 μm and ~8000 μm(2), respectively. The simplified Hummer's method provides a facile approach for the preparation of large-area GO.

Fulltext Asbestosis in Malaysia: report on first two cases

Lim HH, Rampal KG, Joginder S, Abu Bakar CM, Chan KH, Vivek TN

Med J Malaysia, 1999 Sep;54(3):364-7.

PMID: 11045065

The first two cases of asbestosis in Malaysia are reported. Both had considerable occupational exposure to asbestos dust in the past, with a long latency period exceeding 30 years. One case presented with distinctive clinical and radiological features, while the other case was only confirmed by histological diagnosis. The usefulness of modern investigation techniques such as CT scan in the diagnosis of asbestosis is also illustrated.

Fulltext Respiratory conditions in Malaysian asbestos cement workers

Lim HH, Rampal KG, Joginder S, Abu Bakar CM, Chan KH, Vivek TN

Med J Malaysia, 2002 Sep;57(3):340-7.

PMID: 12440274 MyJurnal

A cross-sectional study was conducted to determine the prevalence and type of respiratory conditions including asbestos-related diseases among Malaysian asbestos cement workers. The study population consisted of 1164 workers who had undergone medical surveillance from 1995 to 1997, including full history, physical examination, chest radiography and spirometry. More than half the male workers were smokers or ex-smokers, with smokers having more respiratory symptoms and signs, and reduced FEV1 compared with non smokers. The five most common respiratory conditions diagnosed were bronchial asthma, chronic bronchitis, pulmonary tuberculosis, upper respiratory tract infections and allergic rhinitis. On follow-up, there were also two cases of asbestosis and one case of bronchial carcinoma. The asbestosis cases were probably related to heavy occupational exposure to asbestos fibres in the past, before governmental regulations were gazetted in 1986. Further follow-up is essential for continued monitoring of the health status of asbestos workers.

Displaying publications 21 - 40 of 59 in total