Displaying publications 141 - 160 of 288 in total

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  1. Fulltext Melioidosis in Pahang, Malaysia
    How SH, Ng KH, Jamalludin AR, Shah A, Rathor Y
    Med J Malaysia, 2005 Dec;60(5):606-13.
    PMID: 16515112
    We conducted a retrospective review of 135 patients with melioidosis in Pahang from January 2000 to June 2003. Patients were mostly male (78.5%) and Malay (83%) with a median age of 51 years. Seventy four percent of patients were diabetic. Common presentations were pneumonia (40.7%), septicaemic without obvious source of infection (19.3%) and multiple organ involvement (15.6%). Only 32.7% were given appropriate antibiotics empirically. The overall mortality was 54% with most deaths (65%) occurring within 48 hours of admission. Patients with pneumonia, multiple organ involvement and septicaemic of unknown source had higher mortality as compared to patients with subcutaneous, musculoskeletal or single internal organ involvement without pneumonia (p < 0.001). The relapse rate was 19.2%.
  2. Computed and conventional chest radiography: a comparison of image quality and radiation dose
    Ramli K, Abdullah BJ, Ng KH, Mahmud R, Hussain AF
    Australas Radiol, 2005 Dec;49(6):460-6.
    PMID: 16351609
    The aim of this study was to compare the image quality and entrance skin dose (ESD) for film-screen and computed chest radiography. Analysis of the image quality and dose on chest radiography was carried out on a conventional X-ray unit using film-screen, storage phosphor plates and selenium drum direct chest radiography. For each receptor, ESD was measured in 60 patients using thermoluminescent dosemeters. Images were printed on 35 x 43 cm films. Image quality was assessed subjectively by evaluation of anatomic features and estimation of the image quality, following the guidelines established by the protocols of the Commission of the European Communities. There was no statistically significant difference noted between the computed and conventional images (Wilcoxon rank sum test, P > 0.05). Imaging of the mediastinum and peripheral lung structures were better visualized with the storage phosphor and selenium drum technique than with the film-screen combination. The patients' mean ESD for chest radiography using the storage phosphor, film-screen combination and selenium drum was 0.20, 0.20 and 0.25 mGy, respectively, with no statistically significant difference with P > 0.05 (chi(2) tests).
  3. An indicator device for monitoring of room illuminance level in the radiological image viewing environment
    Azlan CA, Ng KH, Anandan S, Nizam MS
    Australas Phys Eng Sci Med, 2006 Sep;29(3):278-80.
    PMID: 17058591
    Illuminance level in the softcopy image viewing room is a very important factor to optimize productivity in radiological diagnosis. In today's radiological environment, the illuminance measurements are normally done during the quality control procedure and performed annually. Although the room is equipped with dimmer switches, radiologists are not able to decide the level of illuminance according to the standards. The aim of this study is to develop a simple real-time illuminance detector system to assist the radiologists in deciding an adequate illuminance level during radiological image viewing. The system indicates illuminance in a very simple visual form by using light emitting diodes. By employing the device in the viewing room, illuminance level can be monitored and adjusted effectively.
  4. Fulltext Quality assurance in mammography: College of Radiology Survey in Malaysia
    Ho EL, Ng KH, Wong JH, Wang HB
    Med J Malaysia, 2006 Jun;61(2):204-8.
    PMID: 16898312
    Malaysia's mammography QA practice was surveyed based on the Malaysian Ministry of Health and the American College of Radiology (ACR) requirements. Data on mammography unit, processor, image receptor, exposure factors, mean glandular dose (MGD), sensitometry, image quality and viewbox luminance were obtained. Mean developer temperature and cycle time were 34.1 +/- 1.8degreesC and 107.7 +/- 33.2 seconds. Mean base+fog level, speed index and contrast index were 0.20+/-0.01, 1.20+/-0.01 and 1.33+/-0.26 respectively. Eighty-six percent of the fifty centres passed the image quality test while 12.5% complied with ACR recommended viewbox luminance. Average MGD was 1.0+/-0.4 mGy. Malaysia is on the right track for QA but with room for total quality improvement.
  5. A proposed hierarchical fuzzy inference system for the diagnosis of arthritic diseases
    Lim CK, Yew KM, Ng KH, Abdullah BJ
    Australas Phys Eng Sci Med, 2002 Sep;25(3):144-50.
    PMID: 12416592 DOI: 10.1007/BF03178776
    Development of computer-based medical inference systems is always confronted with some difficulties. In this paper, difficulties of designing an inference system for the diagnosis of arthritic diseases are described, including variations of disease manifestations under various situations and conditions. Furthermore, the need for a huge knowledge base would result in low efficiency of the inference system. We proposed a hierarchical model of the fuzzy inference system as a possible solution. With such a model, the diagnostic process is divided into two levels. The first level of the diagnosis reduces the scope of diagnosis to be processed by the second level. This will reduce the amount of input and mapping for the whole diagnostic process. Fuzzy relational theory is the core of this system and it is used in both levels to improve the accuracy.
  6. Discriminant analysis of normal and malignant breast tissue based upon INAA investigation of elemental concentration
    Ng KH, Ong SH, Bradley DA, Looi LM
    Appl Radiat Isot, 1997 Jan;48(1):105-9.
    PMID: 9022216
    Discriminant analysis of six trace element concentrations measured by instrumental neutron activation analysis (INAA) in 26 paired-samples of malignant and histologically normal human breast tissues shows the technique to be a potentially valuable clinical tool for making malignant-normal classification. Nonparametric discriminant analysis is performed for the data obtained. Linear and quadratic discriminant analyses are also carried out for comparison. For this data set a formal analysis shows that the elements which may be useful in distinguishing between malignant and normal tissues are Ca, Rb and Br, providing correct classification for 24 out of 26 normal samples and 22 out of 26 malignant samples.
  7. Development and evaluation of a computer expert system for the management of fetal distress
    Wong KK, Ng KH, Nah SH, Yusof K, Rajeswari K
    Asia Oceania J Obstet Gynaecol, 1994 Mar;20(1):19-23.
    PMID: 8172522
    The general lack of specialist obstetricians in a developing country such as Malaysia prompted us to develop a computer expert system for the management of fetal distress in rural hospitals. It was based on accepted production rules and implemented on a microcomputer. The clinical prototype was evaluated by 8 specialist obstetricians and 21 non-specialist doctors involved in obstetric care. The initial impression was that this type of expert system may help in diagnosis, decision-making and teaching.
  8. Immunolabelling of prolactin at ultrastructural level using the protein A-gold technique on Epon-embedded tissue
    Ng KH, Tan KL, Gan SK, Looi LM
    Malays J Pathol, 1992 Jun;14(1):29-33.
    PMID: 1469915
    The use of the colloidal-gold technique in electron microscopy immunocytochemistry has provided important information on the in situ localisation of intracellular antigens. We have developed a post-embedding technique for prolactin localisation on resin-embedded human pituitary tissue sections by the use of the protein-A gold conjugate. Human pituitary tissue obtained at autopsy was processed for electron microscopical study without post-osmication and then embedded in Epon. The indirect immunoperoxidase method was used for light microscopical targetting of lactotroph cells for subsequent electron microscopical antigen localisation. Ultra-thin sections were labelled with human anti-human prolactin followed by protein-A gold conjugate. Specific labelling was observed over secretory granules with a density of 15-30 particles per granule, as determined by the Quantimet 570 image analysis system. This technique provides a means of studying the pathophysiology of hormonal secretion at ultrastructural level and can be a useful tool in diagnostic and research investigations.
  9. Fulltext Laparoscopic sterilization with fallope rings - a Malaysian experience
    Abdul Rahman A, Sinnathuray TA, Sivanesaratnam V, Ng KH
    Med J Malaysia, 1981 Jun;36(2):92-9.
    PMID: 6211595
    The early Malaysian experience of laparoscopic sterilisation with the Fallope tubal rings, as undertaken at the Obstetrical and Gynaecological Unit of the University Hospital, University of Malaya in Kuala Lumpur, Malaysia is reported in a study of 291 consecutive females that had had the procedure undertaken during the one year period, May 1975 to April 1976. Of the 291 cases, 247 women were sterilised in the "interval" period, 43 after "menstrual regulation" procedure and one after a spontaneous abortion. General anaesthesia was used in all except one case. The salient socio-demographic, contraceptive and reproductive characteristics of study cases are presented and discussed. The technical problems, the early complications and morbidity encountered in this study are presented and discussed in the light of other similar studies, and in relation to sterilisation by laparoscopic tubal electrocoagulation. The overall impression is that laparoscopic sterilisation with the Fallope tubal rings is preferred to that by tubal electrocoagulation, in view of the possible inadvertent serious electrical burns of other structures during the use of the latter procedure.
  10. Squamous cell carcinoma of the oral mucosa in Malaysia--any change?
    Ng KH, Siar CH, Ramanathan K, Murugasu P, Chelvanayagam PI
    Southeast Asian J. Trop. Med. Public Health, 1985 Dec;16(4):602-6.
    PMID: 3835704
    The prevalence rate of 749 cases of oral squamous cell carcinomas (SCC) recorded between 1978-1984 was studied. Results showed that the Indians formed the dominant group (63.8%) followed by the Malays (19.6%) and Chinese (16.6%). The peak incidences were generally located between the sixth and eighth decades. Only in the Chinese group a male preponderance was noted. In the Indians, the buccal mucosa was the most prevalent site; in the Malays and Chinese males, the gingiva and alveolus; and the Chinese female, the tongue. In all three groups, the well-differentiated SCC was the commonest type and the poorly differentiated least common.
  11. Osteosarcoma presenting as an aggressive nodular mass in the region of the mandible
    Ong ST, Shim CK, Ng KH, Siar CH
    J Oral Sci, 2004 Mar;46(1):55-9.
    PMID: 15141725
    Osteosarcomas are highly malignant neoplasms of bone that are challenging to diagnose. These neoplasms often show atypical behavior. In the initial phase they may present as nondescript bony swellings with an indolent growth rate, only to become overtly aggressive and malignant towards the later phase of the disease. Similarly, the histological growth pattern of this neoplasm can be quite diverse, presenting with areas that mimic benign myofibroblastic tumors, giant cell granulomatous conditions and partial encapsulation. The final diagnosis of an osteosarcoma is often reached after thorough sampling and examination of multiple biopsy specimens. All these clinical features and histological diagnostic difficulties were encountered in a case of osteosarcoma affecting the right mandible of a 62-year-old Chinese woman described here. The diagnostic lessons accrued from this case are discussed.
  12. Osteoma of the condyle as the cause of limited-mouth opening: a case report
    Siar CH, Jalil AA, Ram S, Ng KH
    J Oral Sci, 2004 Mar;46(1):51-3.
    PMID: 15141724
    Osteoma is a benign tumour consisting of mature bone tissue. It is an uncommon lesion that occurs mainly in the bones of the craniofacial complex. Only a few cases involving the condylar process have been reported. An osteoma of the left condyle causing limited mouth-opening in a 32-year-old Malaysian Chinese female is reported here to alert the practitioner to consider this lesion as a diagnostic possibility in instances of trismus or limited-mouth opening.
  13. Atypical peripheral ameloblastoma of the palate
    Siar CH, Ng KH, Ngui CH, Chuah CH
    J Laryngol Otol, 1990 Mar;104(3):252-4.
    PMID: 2341785
    Clinical, radiological and histological characteristics of the peripheral ameloblastoma are briefly outlined. A case found occurring in the palate and presenting with atypical histological features is reported. The differential diagnosis of this lesion, its treatment and histogenesis are discussed.
  14. A comparative study of radiation doses between phantom and patients via CT angiography of the intra-/extra-cranial, pulmonary, and abdominal/pelvic arteries
    Karim MKA, Sabarudin A, Muhammad NA, Ng KH
    Radiol Phys Technol, 2019 Dec;12(4):374-381.
    PMID: 31468370 DOI: 10.1007/s12194-019-00532-8
    This study aimed to evaluate effective dose and size-specific dose estimate (SSDE) of computed tomography angiography (CTA) examination using an anthropomorphic phantom. We included three CTA examination protocols to evaluate the intra- and extra-cranial arteries, pulmonary artery (CTPA), and abdominal vessels. Patient SSDEs were measured retrospectively to estimate patient dose, relative to the bodyweight of the patient and volume CT dose index (CTDIvol). Our findings revealed that the highest dose was absorbed by the left lobe of the thyroid gland during intra-/extra-cranial CTA and CTPA, that is, 14.11 ± 0.24 mGy and 16.20 ± 3.95 mGy, respectively. However, the highest absorbed dose in abdominal/pelvic CTA was the gonads (8.98 ± 0.30 mGy), while other radiosensitive organs in intra- and extra-cranial CTA, CTPA, and abdominal/pelvic CTA did not demonstrate significant differences between organs/structures with p value 0.88, 0.11, and 0.54, respectively. The estimated effective dose in intra-/extra-cranial CTA was lower in patients (0.80 ± 0.60 mSv) than in the phantom (0.83 mSv), but it was the opposite for CTPA, with the effective dose being higher in patients (7.54 ± 3.09 mSv) than in the phantom (6.68 mSv). Similar to the effective dose, only CTPA SSDEs were significantly higher in men than in women (19.74 ± 4.79 mGy versus 7.9 mGy). Effective dose and SSDE are clinically relevant parameters that can help estimate a more accurate patient dose based on a patient's size.
  15. Fulltext A review on the accuracy of bladder cancer detection methods
    Zhu CZ, Ting HN, Ng KH, Ong TA
    J Cancer, 2019;10(17):4038-4044.
    PMID: 31417648 DOI: 10.7150/jca.28989
    Background and purpose: Bladder cancer is the most common malignant tumour in the urinary system, with a high incidence and recurrence rate. While the incidence of bladder cancer has been rising in recent years, the prevalence of bladder carcinoma is showing an increasing tendency in the younger age group. There are several methods to detect bladder cancer, but different methods have varying degrees of accuracy which intrinsically depends on the method's sensitivity and specificity. Our aim was to comprehensively summarize the current detection methods for bladder cancer based on the available literature, and at the same time, to find the best combination of different effective methods which can produce a high degree of accuracy in detecting the presence of cancerous cells in the bladder. Materials and Methods: We used key word retrieval method for searching related references in English that had been indexed in PubMed and Medline. Results and Discussion: This paper discussed the different detection methods and their sensitivities/specificities as well as the advantages and disadvantages. We summarized the best identified cancer cell detection methods with higher sensitivity/specificity. Conclusion: The results of this review can positively help to identify accurate methods for detecting bladder cancer and highlight areas to be further improved for future research work.
  16. Elimination of energy-consuming mechanical stirring: Development of auto-suspending ZnO-based photocatalyst for organic wastewater treatment
    Ng KH, Chen K, Cheng CK, Vo DN
    J Hazard Mater, 2021 05 05;409:124532.
    PMID: 33221078 DOI: 10.1016/j.jhazmat.2020.124532
    Powdered-photocatalysis of organic wastewater is widely investigated, unfortunately not industrially implemented due to its high energy requirement. Interestingly, such issue may be alleviated via the elimination of mechanical stirring required. Core-shell ZnO-based photocatalysts were developed herein, subsequently demonstrated efficient photocatalytic activities in the absence of mechanical stirring. Results show that the developed SiO2-cored ZnO photocatalyst are highly crystalline, while significantly smaller than coreless, pure ZnO due to the multi-point crystallization prompted. Additionally, it is also inherited with considerable buoyancy ability from SiO2-core in the absence of mechanical stirring, concurrently rendered with UV-active properties due to its ZnO-shell. Experimentally, 55% of particles of ZnO_0.0025 (0.0025 mol of ZnO-deposition) were found stably suspended for 60 min in liquid substrate, as opposed to the instant-settling of pure ZnO particles. In term of photocatalytic activity, ZnO_0.01 manifested the best methylene blue (MB) degradation with 150 mL/min of O2-bubbling. 67.63% of MB was degraded with photocatalyst loading of 0.2 g/L after 120 min UV-irradiation, simultaneously recorded the highest pseudo-first order reaction constant of 9.636 × 10-3 min-1. As summary, the auto-suspending photocatalysis conceptualized in current study offers a high possibility in reducing energy requirement for photo-treatment of wastewater, hence advocating its industrialization potential in near future.
  17. Fulltext The use of radiochromic EBT2 film for the quality assurance and dosimetric verification of 3D conformal radiotherapy using Microtek ScanMaker 9800XL flatbed scanner
    Sim GS, Wong JH, Ng KH
    J Appl Clin Med Phys, 2013 Jul 08;14(4):4182.
    PMID: 23835383 DOI: 10.1120/jacmp.v14i4.4182
    Radiochromic and radiographic films are widely used for radiation dosimetry due to the advantage of high spatial resolution and two-dimensional dose measurement. Different types of scanners, including various models of flatbed scanners, have been used as part of the dosimetry readout procedure. This paper focuses on the characterization of the EBT2 film response in combination with a Microtek ScanMaker 9800XL scanner and the subsequent use in the dosimetric verification of a 3D conformal radiotherapy treatment. The film reproducibility and scanner uniformity of the Microtek ScanMaker 9800XL was studied. A three-field 3D conformal radiotherapy treatment was planned on an anthropomorphic phantom and EBT2 film measurements were carried out to verify the treatment. The interfilm reproducibility was found to be 0.25%. Over a period of three months, the films darkened by 1%. The scanner reproducibility was ± 2% and a nonuniformity was ±1.9% along the direction perpendicular to the scan direction. EBT2 measurements showed an underdose of 6.2% at high-dose region compared to TPS predicted dose. This may be due to the inability of the treatment planning system to predict the correct dose distribution in the presence of tissue inhomogeneities and the uncertainty of the scanner reproducibility and uniformity. The use of EBT2 film in conjunction with the axial CT image of the anthropomorphic phantom allows the evaluation of the anatomical location of dose discrepancies between the EBT2 measured dose distribution and TPS predicted dose distribution.
  18. Fulltext Modelling knowledge, health beliefs, and health-promoting behaviours related to cardiovascular disease prevention among Malaysian university students
    Lim BC, Kueh YC, Arifin WN, Ng KH
    PLoS One, 2021;16(4):e0250627.
    PMID: 33909664 DOI: 10.1371/journal.pone.0250627
    BACKGROUND: Healthy lifestyle habits formed during young adulthood may have a sustaining impact on health across later life. The current study aimed to test the theoretical model of factors (selected demographic variables, knowledge of heart disease, health belief related to cardiovascular disease (CVD), self-efficacy, cues to action, and screening intention) influencing health-promoting behaviours among Malaysian university students.

    METHODS: In a cross-sectional survey, the undergraduate students in Universiti Sains Malaysia were invited to complete the self-administered questionnaires. Participants were selected using a purposive sampling method. The proposed hypothesised model was analysed using a structural equation modelling with Mplus 7.3 program. A total of 788 (70.7% female) undergraduate students with a mean age of 20.2 (SD = 1.02) participated in the study. The primary outcome of knowledge, health beliefs, and health-promoting behaviours related to CVD were measured by questionnaires namely: Knowledge of Heart Disease, Health Beliefs Related to CVD, and Health Promoting Lifestyle Profiles-II.

    RESULTS: The final hypothetical structural model showed a good fit to the data based on several fit indices: with comparative fit index (CFI) at .921, standardised root mean square residual (SRMR) at .037, and root mean square error of approximation (RMSEA) at .044 (90% CI: .032, .054). The final structural model supported 13 significant path estimates. These variables explained 12% of the total variance in health-promoting behaviours. Through perceived benefits, total knowledge had an indirect effect on health-promoting behaviours.

    CONCLUSION: The results suggest that perceived barriers, perceived benefits, family history of CVD, and screening intention enable young adults to engage in health-promoting behaviours.

  19. Fulltext Validation of Health Promoting Lifestyle Profile. II: A confirmatory study with a Malaysian undergraduate students sample
    Lim BC, Kueh YC, Arifin WN, Ng KH
    Education in Medicine Journal, 2016;8(2):65-77.
    MyJurnal
    Objective: To determine the factor structure of the Health Promoting Behaviours (HPB) component of Health Promoting Lifestyle Profile-II among undergraduate students in Universiti Sains Malaysia (USM) by confirmatory factor analysis (CFA).
    Methods: A cross sectional study was conducted among undergraduate students. The data was collected in the USM campus using a proportionate cluster sampling method. The HPB questionnaire was handed to students in the lecture hall and collected immediately when the lecture finished. CFA was conducted using robust maximum likelihood estimation due to violation of multivariate normality assumption. A three-factor model was tested for measurement model validity and construct validity.
    Results: A total of 788 students participated in the study. CFA of a 21-item, three-factor model yielded an adequate goodness-of-fit values. The measurement model also showed a good convergent and discriminant validity after model re-specification.
    Conclusion: The health promoting behaviours scale was proven to have a valid measurement model and reliable constructs. It was deemed suitable for use to measure the health promoting behaviours components of a healthy lifestyle among Malaysian undergraduate students. It was recommended to further conduct cross-validation studies in other Malaysian public universities to provide additional empirical evidence to support its use.
  20. Optimization of photocatalytic degradation of palm oil mill effluent in UV/ZnO system based on response surface methodology
    Ng KH, Cheng YW, Khan MR, Cheng CK
    J Environ Manage, 2016 Dec 15;184(Pt 3):487-493.
    PMID: 27784576 DOI: 10.1016/j.jenvman.2016.10.034
    This paper reports on the optimization of palm oil mill effluent (POME) degradation in a UV-activated-ZnO system based on central composite design (CCD) in response surface methodology (RSM). Three potential factors, viz. O2 flowrate (A), ZnO loading (B) and initial concentration of POME (C) were evaluated for the significance analysis using a 2(3) full factorial design before the optimization process. It is found that all the three main factors were significant, with contributions of 58.27% (A), 15.96% (B) and 13.85% (C), respectively, to the POME degradation. In addition, the interactions between the factors AB, AC and BC also have contributed 4.02%, 3.12% and 1.01% to the POME degradation. Subsequently, all the three factors were subjected to statistical central composite design (CCD) analysis. Quadratic models were developed and rigorously checked. A 3D-response surface was subsequently generated. Two successive validation experiments were carried out and the degradation achieved were 55.25 and 55.33%, contrasted with 52.45% for predicted degradation value.
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