MyMedR

Quaternized wood as sorbent for reactive dyes

Low KS, Lee CK, Tan BF

Appl Biochem Biotechnol, 2000 Jun;87(3):233-45.

Various species of local wood modified with N-(3-chloro-2-hydroxypropyl)-trimethylammonium chloride showed sorption enhancement for hydrolyzed Reactive Blue 2 (HRB) compared to the untreated samples. The enthalpy of sorption of HRB on Simpoh (Dillenia suffruticosa) was found to be endothermic. Maximum sorption capacity calculated from the Langmuir isotherm was 250.0 mg/g. Under continuous flow conditions HRB could be successfully removed. Dye removal was a function of bed depth and flow rate. However, the bed depth service time model of Bohart and Adams was not applicable in the HRB-quaternized wood system. The modified wood was applied to a sample of industrial textile effluent, and it was found to be able to remove the color successfully under batch conditions.

Hexane-extracted spent bleaching earth as a sorbent for copper in aqueous solution

Low KS, Lee CK, Lee TS

Bull Environ Contam Toxicol, 1996 Mar;56(3):405-12.

PMID: 8825962

Removal of chromium (III) from aqueous solution using chrome sludge

Low KS, Lee CK, Ow-Wee ST

Bull Environ Contam Toxicol, 1995 Aug;55(2):270-5.

PMID: 7579934

Chromium(III) sorption enhancement through NTA--modification of biological materials

Low KS, Lee CK, Lee PL

Bull Environ Contam Toxicol, 1997 Mar;58(3):380-6.

PMID: 9008046

Copper vapour laser ID labelling on metal dentures and restorations

Ling BC, Nambiar P, Low KS, Lee CK

J Forensic Odontostomatol, 2003 Jun;21(1):17-22.

PMID: 12793127

Denture marking is accepted as a means of identifying dentures and persons in geriatric institutions, or post-mortem during war, crimes, civil unrest, natural and mass disasters. Labelling on the acrylic resin component of the denture can easily be damaged or destroyed by fire but on cobalt-chromium components it would be more resistant. A copper vapour laser (CVL) can be used to label the cobalt-chromium components of dentures and metal restorations easily, and legibly, and miniaturised for the incorporation of more personal particulars necessary for the identification of the deceased person. The CVL beam is focussed by its optics and delivered to the material surface by the two-axis scanner mounted with mirrors. A personal computer controls the movement of the scanner and the firing of the CVL. The high peak power of the pulsed CVL is focussed to very high energy density producing plasma ablation of the alloy surface. Very fine markings of a few microns width can be produced enabling the storage of detailed information of the deceased person on a metal surface for the purpose of rapid identification.

The kinetics of bioaccumulation of zinc, copper, lead and cadmium by oysters (Crassostrea iredalei and C. belcheri) under tropical field conditions

Lim PE, Lee CK, Din Z

Sci Total Environ, 1998 May 14;216(1-2):147-57.

PMID: 9618930

A study on the kinetics of accumulation and depuration of Zn, Cu, Pb and Cd by the oysters (Crassostrea iredalei and Crassostrea belcheri) cultured at two locations in the Merbok Estuary, Malaysia was conducted. A first-order kinetic model was employed to fit the experimental data in order to estimate the rate constants for uptake and elimination processes and to predict the bioconcentration factors (BCF). Among the four metals studied, only the Zn accumulation process could not be modelled using first-order kinetics. The elimination rate constants estimated from depuration data for C. iredalei are found to be much greater than those from accumulation data. The results suggest that the values of kinetic parameters and BCFs derived under conditions of both aqueous and dietary exposure are probably more site- than species-specific.

Fulltext Bullous pemphigoid in an elderly patient with myelodysplastic syndrome and refractory anemia coupled with excess of blast

Lee YY, Bee PC, Lee CK, Naiker M, Ismail R

Ann Dermatol, 2011 Dec;23(Suppl 3):S390-2.

PMID: 22346286 DOI: 10.5021/ad.2011.23.S3.S390

Bullous pemphigoid (BP) has a recognized association with solid organ tumors, but is relatively rare in hematological malignancies. We report a 67-year-old male who developed BP after being diagnosed with myelodysplastic syndrome and refractory anemia with excess of blast (RAEB). Skin biopsy elucidated sub-epidermal bulla using direct immunofluorescence, revealing linear C3 and IgG deposits along the basement membrane. His BP was recalcitrant to the conventional treatment and only responded to a combination of high dose oral prednisolone and azathioprine. The relative refractory nature of his condition and concurrent RAEB supports a paraneoplastic nature.

Comparison of noninvasive screening tools for hepatic fibrosis, association with methotrexate cumulative dose, and risk factors in psoriasis patients

Lee JHM, Loo CH, Tan WC, Lee CK, Jamil A, Khor YH

Dermatol Ther, 2022 Jan;35(1):e15203.

PMID: 34779102 DOI: 10.1111/dth.15203

Methotrexate (MTX) is a first-line systemic psoriasis therapy with risk of liver fibrosis. Noninvasive tools for liver fibrosis screening are Fibroscan®, Fibrosis-4 (FIB-4) index, and aspartate aminotransferase-to-platelet ratio (APRI) index. To compare Fibroscan®, FIB-4, and APRI in detecting fibrosis, determine association of fibrosis with MTX cumulative dose, and explore risk factors for fibrosis. A case-control study involving psoriasis patients aged ≥18 years with MTX cumulative dose ≥1 g, with age and sex-matched MTX naïve psoriasis patients was performed. Noninvasive tools were used to assess liver fibrosis. Sixty-one patients on MTX and 54 controls participated. Fibroscan® detected fibrosis in 22 (36.1%) patients on MTX compared to 11 (19.6%) controls (p = 0.05). FIB-4 predicted fibrosis in 13 (21.3%) patients on MTX and in 10 (17.9%) controls (p = 0.64) while APRI diagnosed 7 (11.5%) versus 7 (12.5%), p = 0.65. No significant correlation between Fibroscan® assessed liver stiffness and MTX cumulative dose (p = 0.47). Independent risk factors for liver fibrosis were MTX use with raised alanine aminotransferase (OR = 68.56, 95% CI 8.26; 568.86, p

Fulltext Ultra Long Construct Minimally Invasive Spinal Stabilization Using Percutaneous Pedicle Screws in the Treatment of Symptomatic Multicentric Spinal Metastasis

Lee CK, Chan CY, Kwan MK

Asian Spine J, 2015 Dec;9(6):962-5.

PMID: 26713131 DOI: 10.4184/asj.2015.9.6.962

Managing multiple level spinal metastases is challenging. We report the case of a 58-year-old female with advanced lung cancer who presented with multiple pathological fractures of the thoracic spine (T5, T6, T7, and T8 vertebrae). She was treated with palliative radiotherapy. Her resting pain improved, but the instability pain persisted. One month later, she had a trivial fall leading to a pathological fracture of the L2 vertebra with cauda equine syndrome. The patient was treated surgically with minimally invasive decompression of the L2 and with percutaneous instrumented stabilization using an ultra-long construct from T3 to L5 (15 spinal levels), spanning the previously radiated zone and the decompression site. Postoperatively, she had significant improvements in pain and neurology. There were no surgical complications. Ultra long construct minimally invasive spinal stabilization is the ideal approach for symptomatic multicentric spinal metastasis with poor prognostic scores. Using this technique, the goals of spinal stabilization and direct neural decompression can be achieved with minimal morbidity.

Fingerprint verification prediction model in hand dermatitis

Lee CK, Chang CC, Johor A, Othman P, Baba R

Int J Dermatol, 2015 Jul;54(7):765-70.

PMID: 25427962 DOI: 10.1111/ijd.12451

Hand dermatitis associated fingerprint changes is a significant problem and affects fingerprint verification processes. This study was done to develop a clinically useful prediction model for fingerprint verification in patients with hand dermatitis.

Fingerprint changes and verification failure among patients with hand dermatitis

Lee CK, Chang CC, Johar A, Puwira O, Roshidah B

JAMA Dermatol, 2013 Mar;149(3):295-9.

PMID: 23682364

To determine the prevalence of fingerprint verification failure and to define and quantify the fingerprint changes associated with fingerprint verification failure.

Fulltext Influenza A (H1N1) 2009 pandemic virus: learning from the first wave, preparing for the second

Lee CK

Med J Malaysia, 2010 Mar;65(1):1-2.

PMID: 21265237

In a short period of two months, the novel influenza A/H1N1 virus has circumnavigated the entire planet leaving behind in its wake approximately 3000 reported deaths worldwide. Fortunately, in many areas around the world, September 2009 brought a lull in the number of new H1N1 infections. This brought welcomed relief in many countries that had earlier experienced high respiratory disease activity in their communities. However, based on previous influenza pandemics, this reprieve may well be short-lived. As the Northern hemisphere approaches its winter months, many experts are now predicting a second wave of influenza A/H1N1 infections. This prediction maybe well placed as all 3 influenza pandemics in the last century reported second or even subsequent waves of new infections, all of which appeared to be more severe than the primary event (ref). The timing of these second waves have varied from 6 months to 3 years and invariably seemed to be linked to the winter months. It is unclear precisely what changes caused the increased severity seen during the second waves; one possibility is the progressive adaptation of the novel influenza virus to its new human host . Molecular analysis, for example, suggests that the 1918 Spanish influenza virus that emerged during the second wave had undergone changes in the hemagglutinin binding site that increased the binding specificity for human receptors. This is thought to have increased the replicative capacity and hence, the pathogenicity of the virus. It is also evident that as the H1N1 2009 pandemic virus continues to spread, opportunities for adaptation that increases virulence will also increase. Nonetheless, the changes needed for such adaptation and for increased virulence are unpredictable and by no means inevitable

Fulltext Production and Optimization of Cellulase Enzyme Using Aspergillus niger USM AI 1 and Comparison with Trichoderma reesei via Solid State Fermentation System

Lee CK, Darah I, Ibrahim CO

Biotechnol Res Int, 2011;2011:658493.

PMID: 21350665 DOI: 10.4061/2011/658493

Novel design solid state bioreactor, FERMSOSTAT, had been evaluated in cellulase production studies using local isolate Aspergillus niger USM AI 1 grown on sugarcane bagasse and palm kernel cake at 1 : 1 (w/w) ratio. Under optimised SSF conditions of 0.5 kg substrate; 70% (w/w) moisture content; 30°C; aeration at 4 L/h · g fermented substrate for 5 min and mixing at 0.5 rpm for 5 min, about 3.4 U/g of Filter paper activity (FPase) was obtained. At the same time, comparative studies of the enzymes production under the same SSF conditions indicated that FPase produced by A. niger USM AI 1 was about 35.3% higher compared to Trichoderma reesei. This shows that the performance of this newly designed SSF bioreactor is acceptable and potentially used as prototype for larger-scale bioreactor design.

Fulltext Changing approaches in HIV testing

Lee CK

Med J Malaysia, 2007 Mar;62(1):1-2.

PMID: 17682559 MyJurnal

In 1985, when HIV testing first became available, the main goal of such testing was to ensure blood safety. Hemophiliacs and other patients who were transfusion-dependent were the initial patients that needed to be protected as they were exposed to iatrogenic risk. It dawned very quickly to health authorities even then that alternative testing sites had to be quickly established to deter persons from using blood bank facilities for HIV testing purposes. At that time, professional opinion was divided regarding the value of HIV testing and whether HIV testing should be encouraged because no consensus existed regarding whether a positive test predicted transmission to sex partners or from mother to infant. No effective treatment existed then and stigma and discrimination faced by those who were found positive was rampant in many parts of the world. Counseling was designed, in part, to ensure that persons tested were aware of the implications of a positive result and in part, to address the person’s risk behavior to reduce transmission to others.

Enzymatic deinking of laser printed office waste papers: some governing parameters on deinking efficiency

Lee CK, Darah I, Ibrahim CO

Bioresour Technol, 2007 May;98(8):1684-9.

PMID: 17137782

The protocol for the enzymatic deinking of laser printed waste papers on a laboratory scale using cellulase (C) and hemicellulase (H) of Aspergillus niger (Amano) was developed as an effective method for paper recycling. A maximum deinking efficiency of almost 73% by the enzyme combination of C:H was obtained using the deinking conditions of pulping consistency of 1.0% (w/v) with the pulping time of 1.0min, temperature of 50 degrees C, pH=3.5, agitation rate of 60rpm, pulp concentration of 4% (w/v), concentration of each enzyme of 2.5U/g air dried pulp and the enzyme ratio of 1:1. The deinking efficiency was further enhanced to 95% using the optimized flotation system consisting of pH=6.0, Tween 80 of concentration 0.5% (w/w), working air flow rate of 10.0L/min and temperature of 45 degrees C. The deinked papers were found to exhibit properties comparable to the commercial papers suggesting the effectiveness of the enzymatic process developed.

Fulltext Antimicrobial gauze as a dressing reduces pin site infection: a randomized controlled trial

Lee CK, Chua YP, Saw A

Clin Orthop Relat Res, 2012 Feb;470(2):610-5.

PMID: 21842299 DOI: 10.1007/s11999-011-1990-z

Pin site infection is a common problem in external fixation. Plain gauze wetted with normal saline is commonly used for a pin site dressing owing to the simplicity and low cost. Evidence to support adding an antimicrobial agent in the dressing material is lacking.

Is C1 lateral mass screw placement safe for the Chinese, Indians, and Malays? An analysis of 180 computed tomography scans

Lee CK, Tan TS, Chan C, Kwan MK

J Orthop Surg (Hong Kong), 2017 01;25(1):2309499017692683.

PMID: 28211302 DOI: 10.1177/2309499017692683

INTRODUCTION: C1 lateral mass (C1LM) screw is a common procedure in spine surgery. However, related studies are lacking in Asia. We aim to determine the safety of C1LM screw for the Chinese, Indians, and Malays.

METHODS: Three-dimensional computed tomographies of 180 subjects (60 from each ethnic) were analyzed. The length and angulations of C1LM screw and the location of internal carotid artery (ICA) in relation to C1LM were assessed and classified according to the classification by Murakami et al. The incidence of ponticulus posticus (PP) was determined and the differences among the population of these three ethnics were recorded.

RESULTS: The average base length was 8.5 ± 1.4 mm. The lengths within the lateral mass were between 14.7 ± 1.6 mm and 21.7 ± 2.3 mm. The prevalence of PP was 8.3%. 55.3% (199) of ICA were located in zone 0, 38.3% (138) in zone 1-1, 6.4% (23) in zone 1-2, and none in zone 1-3 and zone 2. The average angulation from the entry point to the ICA was 8.5° ± 6.4° laterally. The mean distance of ICA from C1 anterior cortex was 3.7 ± 1.7 mm (range: 0.6∼11.3). There was no difference in distribution of ICA in zone 1 among the three population (Chinese-47%, Indians-61%, and Malays-53%; p > 0.05).

CONCLUSIONS: No ICA is located medial to the entry point of C1LM screw. If bicortical purchase of C1LM screw is needed, screw protrusion of less than 3 mm or medially angulated is safe for ICA. The incidence of PP is 8.3% with higher prevalence among the Indian population.

Fulltext Surgical Morphometry of C1 and C2 Vertebrae: A Three-Dimensional Computed Tomography Analysis of 180 Chinese, Indian, and Malay Patients

Lee CK, Tan TS, Chan CYW, Kwan MK

Asian Spine J, 2017 Apr;11(2):181-189.

PMID: 28443161 DOI: 10.4184/asj.2017.11.2.181

STUDY DESIGN: Clinical imaging study.

PURPOSE: To study the surgical morphometry of C1 and C2 vertebrae in Chinese, Indian, and Malay patients.

OVERVIEW OF LITERATURE: C1 lateral mass and C2 pedicle screw fixation is gaining popularity. However, there is a lack of C1-C2 morphometric data for the Asian population.

METHODS: Computed tomography analysis of 180 subjects (60 subjects each belonging to Chinese, Indian, and Malay populations) using simulation software was performed. Length and angulations of C1 lateral mass (C1LM) and C2 pedicle (C2P) screws were assessed.

RESULTS: The predicted C1LM screw length was between 23.2 and 30.2 mm. The safe zone of trajectories was within 11.0°±7.7° laterally to 29.1°±6.2° medially in the axial plane and 37.0°±10.2° caudally to 20.9°±7.8° cephalically in the sagittal plane. The shortest and longest predicted C2P screw lengths were 22.1±2.8 mm and 28.5±3.2 mm, respectively. The safe trajectories were from 25.1° to 39.3° medially in the axial plane and 32.3° to 45.9° cephalically in the sagittal plane.

CONCLUSIONS: C1LM screw length was 23-30 mm with the axial safe zone from 11° laterally to 29° medially and sagittal safe zone at 21° cephalically. C2P screw length was 22-28 mm with axial safe zone from 26° to 40° medially and sagittal safe zone from 32° to 46° cephalically. These data serve as an important reference for Chinese, Indian, and Malay populations during C1-C2 instrumentation.

Accuracy of cannulated pedicle screw versus conventional pedicle screw for extra-pedicular screw placement in dysplastic pedicles without cancellous channel in adolescent idiopathic scoliosis: a computerized tomography (CT) analysis

Lee CK, Chan CYW, Gani SMA, Kwan MK

Eur Spine J, 2017 11;26(11):2951-2960.

PMID: 28819799 DOI: 10.1007/s00586-017-5266-5

PURPOSE: This study aimed at studying the accuracy and safety of extra-pedicular screw insertion for dysplastic pedicles in AIS comparing cannulated screw system versus conventional screw system.

METHODS: 104 AIS patients with 1524 pedicle screws were evaluated using CT scan. 302 screws were inserted in dysplastic pedicles using fluoroscopic guidance technique. 155 screws were inserted using a cannulated system (Group 1), whereas 147 screws were inserted using standard screws (Group 2). The pedicle perforations were assessed using a classification by Rao et al.; G0: no violation; G1: <2 mm perforation; G2: 2-4 mm perforation; and G3: >4 mm perforation). For anterior perforations, the pedicle perforations were assessed using a modified grading system (Grade 0: no violation, Grade 1: less than 4 mm perforation; Grade 2: 4 mm to 6 mm perforation; and Grade 3: more than 6 mm perforation).

RESULTS: The perforation rate in Group 1 was 4.5% and in Group 2 was 15.6% (p = 0.001). Most of the perforations were anterior perforations (53.3%). The anterior perforation rate in Group 1 was 1.9% compared to 8.8% in Group 2 (p = 0.009). Group 1 has a medial perforation rate of 1.3% compared to Group 2, 6.1% (p = 0.031). The rate of critical pedicle perforation in Group 1 was 2.6% and in Group 2 was 6.8% (p = 0.102). In Group 1, there were no critical medial perforation but there was one G2 lateral perforation, one G2 superior perforation and two G3 anterior perforations. In Group 2, there were three G2 medial perforations, one G2 lateral perforation, one G2 anterior perforation and five G3 anterior perforations.

CONCLUSION: Usage of cannulated screw system significantly increases the accuracy of pedicle screw insertion in dysplastic pedicles in AIS.

Fulltext Femoral head diameter in the Malaysian population

Lee CK, Kwan MK, Merican AM, Ng WM, Saw LB, Teh KK, et al.

Singapore Med J, 2014 Aug;55(8):436-8.

PMID: 25189306

INTRODUCTION: Hip arthroplasty is commonly performed worldwide. The objective of this study was to determine the diameter of the femoral head in the Malaysian population in relation to gender and race (i.e. among Malay, Chinese and Indian patients).

METHODS: This was a retrospective cross-sectional study performed between January 1995 and December 2006, evaluating the femoral head diameters of all patients aged 50 years and above who underwent hemiarthroplasty at two major hospitals in Malaysia.

RESULTS: A total of 945 femoral heads (663 women, 282 men) were evaluated. The mean age of the patients in our cohort was 75.2 ± 9.4 (range 50-101) years. The mean femoral head diameter (with intact articular cartilage) was 44.9 ± 3.2 (range 38-54) mm. In our study, men had a significantly larger mean femoral head diameter than women (47.7 ± 2.8 mm vs. 43.7 ± 2.4 mm; p < 0.05). Patients of Chinese ethnicity were also found to have significantly larger femoral head diameters, when compared among the three races studied (p < 0.05).

CONCLUSION: Malaysians have a mean femoral head diameter of 44.9 ± 3.2 mm. Among our patients, Chinese patients had a significantly larger femoral head size than Malay and Indian patients. We also found that, in our cohort, men had significantly larger femoral head diameters than women.

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