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Recent Advancement in Disposable Electrode Modified with Nanomaterials for Electrochemical Heavy Metal Sensors

Mohamad Nor N, Ramli NH, Poobalan H, Qi Tan K, Abdul Razak K

Crit Rev Anal Chem, 2023;53(2):253-288.
PMID: 34565248 DOI: 10.1080/10408347.2021.1950521

Heavy metal pollution has gained global attention due to its high toxicity and non-biodegradability, even at a low level of exposure. Therefore, the development of a disposable electrode that is sensitive, simple, portable, rapid, and cost-effective as the sensor platform in electrochemical heavy metal detection is vital. Disposable electrodes have been modified with nanomaterials so that excellent electrochemical properties can be obtained. This review highlights the recent progress in the development of numerous types of disposable electrodes modified with nanomaterials for electrochemical heavy metal detection. The disposable electrodes made from carbon-based, glass-based, and paper-based electrodes are reviewed. In particular, the analytical performance, fabrication technique, and integration design of disposable electrodes modified with metal (such as gold, tin and bismuth), carbon (such as carbon nanotube and graphene), and metal oxide (such as iron oxide and zinc oxide) nanomaterials are summarized. In addition, the role of the nanomaterials in improving the electrochemical performance of the modified disposable electrodes is discussed. Finally, the current challenges and future prospect of the disposable electrode modified with nanomaterials are summarized.
A pilot project on hospital-based universal newborn hearing screening: lessons learned

Mukari SZ, Tan KY, Abdullah A

Int J Pediatr Otorhinolaryngol, 2006 May;70(5):843-51.
PMID: 16246430

This paper reports the performance of a newly implemented hospital-based universal newborn hearing screening programme and the challenges to the effective implementation.
Fulltext The effect of cellulose on crystal formation in the kidneys of guinea pigs fed diet rich in calcium and sodium

Syedhussain S, Tan K, Abu Bakar M

Malays J Nutr, 1996 Mar;2(1):79-86.
PMID: 22692100

Our earlier report showed that diet rich in calcium and sodium fed to guinea pigs can be urolithogenic. In this study, we investigated the effect of adding 3% or 15% cellulose as a source of fiber into similar diet to asses the formation of kidney calculus. From the result, animals fed diet with 3% cellulose showed a relatively high concentration of urinary oxalate, urate and large number of crystals in the kidneys. When the cellulose level was raised to 15%, the concentrations of urinary calcium, urate and the number of crystals formed in the kidneys were lowered. We therefore, conclude that high fiber diet may be beneficial in reducing the incidence of kidney stones of calcium origin.
Multiplex sequencing of SARS-Cov-2 genome directly from clinical samples using the Ion Personal Genome Machine (PGM)

Tan KK, Tiong V, Tan JY, Wong JE, Teoh BT, Abd-Jamil J, et al.

Trop Biomed, 2021 Sep 01;38(3):283-288.
PMID: 34362871 DOI: 10.47665/tb.38.3.069

Various methods have been developed for rapid and high throughput full genome sequencing of SARS-CoV-2. Here, we described a protocol for targeted multiplex full genome sequencing of SARS-CoV-2 genomic RNA directly extracted from human nasopharyngeal swabs using the Ion Personal Genome Machine (PGM). This protocol involves concomitant amplification of 237 gene fragments encompassing the SARS-CoV-2 genome to increase the abundance and yield of viral specific sequencing reads. Five complete and one near-complete genome sequences of SARS-CoV-2 were generated with a single Ion PGM sequencing run. The sequence coverage analysis revealed two amplicons (positions 13 751-13 965 and 23 941-24 106), which consistently gave low sequencing read coverage in all isolates except 4Apr20-64- Hu. We analyzed the potential primer binding sites within these low covered regions and noted that the 4Apr20-64-Hu possess C at positions 13 730 and 23 929, whereas the other isolates possess T at these positions. The genome nucleotide variations observed suggest that the naturally occurring variations present in the actively circulating SARS-CoV-2 strains affected the performance of the target enrichment panel of the Ion AmpliSeq™ SARS CoV 2 Research Panel. The possible impact of other genome nucleotide variations warrants further investigation, and an improved version of the Ion AmpliSeq™ SARS CoV 2 Research Panel, hence, should be considered.
Autochthonous spread of DENV-3 genotype III in Malaysia mitigated by pre-existing homotypic and heterotypic immunity

Tan KK, Nellis S, Zulkifle NI, Sulaiman S, AbuBakar S

Epidemiol Infect, 2018 10;146(13):1635-1641.
PMID: 29860959 DOI: 10.1017/S0950268818001425

Dengue virus type 3 genotype III (DENV-3/III) is widely distributed in most dengue-endemic regions. It emerged in Malaysia in 2008 and autochthonously spread in the midst of endemic DENV-3/I circulation. The spread, however, was limited and the virus did not cause any major outbreak. Spatiotemporal distribution study of DENV-3 over the period between 2005 and 2011 revealed that dengue cases involving DENV-3/III occurred mostly in areas without pre-existing circulating DENV-3. Neutralisation assays performed using sera of patients with the respective infection showed that the DENV-3/III viruses can be effectively neutralised by sera of patients with DENV-3 infection (50% foci reduction neutralisation titres (FRNT50) > 1300). Sera of patients with DENV-1 infection (FRNT50 ⩾ 190), but not sera of patients with DENV-2 infection (FRNT50 ⩽ 50), were also able to neutralise the virus. These findings highlight the possibility that the pre-existing homotypic DENV-3 and the cross-reacting heterotypic DENV-1 antibody responses could play a role in mitigating a major outbreak involving DENV-3/III in the Klang Valley, Malaysia.
Evaluation of commercial serological assays in Malaysia for detection of anti-Zika virus antibodies

Khoo HY, Lee HY, Khor CS, Tan KK, AbuBakar S

Trop Biomed, 2021 Dec 01;38(4):613-621.
PMID: 35001928 DOI: 10.47665/tb.38.4.105

The recommended test guidelines for Zika virus (ZIKV) include using both molecular and serological tools. While the molecular tools are useful for detecting acute infection, the serological tools are useful for the detection of previous infections. Nevertheless, detection of ZIKV-specific antibodies remains a challenge due to the high cross-reactivity between ZIKV and other flaviviruses such as dengue virus (DENV) and Japanese encephalitis virus (JEV). The objective of this study is to evaluate the commercially available enzyme-linked immunosorbent assay (ELISA) for the detection of ZIKV IgG. In this study, we evaluated 6 commercially available anti-ZIKV IgG ELISA kits. Pre-characterized serum panels consisting of 70 sera were selected for the evaluation. The diagnostic accuracy of each ELISA kits was determined and compared to the gold standard, Foci Reduction Neutralization Test (FRNT). The present study established that the performance of the NS1-based anti-ZIKV IgG ELISA kit was superior to that which uses of the E protein as antigen. Overall, commercial ZIKV IgG ELISA showed varying test performances, with some achieving moderate to high test sensitivities and specificities. When compared against the FRNT, the test sensitivities ranged from 7.1% to 78.6%, whereas, the test specificities ranged from 40.0% to 100%. Limitation to the study includes the cross reactivity between flavivirus and specificity of the kit in addressing the cross reactivity.
Detection in Malaysia of a Borrelia sp. From Haemaphysalis hystricis (Ixodida: Ixodidae)

Khoo JJ, Lim FS, Tan KK, Chen FS, Phoon WH, Khor CS, et al.

J Med Entomol, 2017 09 01;54(5):1444-1448.
PMID: 28874019 DOI: 10.1093/jme/tjx131

Spirochetes from the Borrelia genus are known to cause diseases in humans, namely Lyme disease and relapsing fever. These organisms are commonly transmitted to humans by arthropod vectors including ticks, mite, and lice. Here, we report the molecular detection of a Borrelia sp. from a Haemaphysalis hystricis Supino tick collected from wildlife in an Orang Asli settlement in Selangor, Malaysia. Phylogenetic analyses of partial 16s rRNA and flaB gene sequences revealed that the Borrelia sp. is closely related to the relapsing fever group borreliae, Borrelia lonestari, Borrelia miyamotoi, and Borrelia theileri, as well as a number of uncharacterized Borrelia sp. from ticks in Portugal and Japan. To our knowledge, this is the first report of a Borrelia sp. detected in H. hystricis, and in Malaysia. The zoonotic potential of this Borrelia sp. merits further investigation.
Development of a TaqMan minor groove binding probe-based quantitative reverse transcription polymerase chain reaction for the detection and quantification of Zika virus

Chin KL, Teoh BT, Sam SS, Loong SK, Tan KK, Azizan NS, et al.

Trop Biomed, 2022 Dec 01;39(4):518-523.
PMID: 36602210 DOI: 10.47665/tb.39.4.005

Zika virus (ZIKV) infection has emerged as a global health concern following epidemic outbreaks of severe neurological disorders reported in Pacific and Americas since 2016. Therefore, a rapid, sensitive and specific diagnostic test for ZIKV infection is critical for the appropriate patient management and the control of disease spread. A TaqMan minor groove binding (MGB) probe-based quantitative reverse transcription-polymerase chain reaction (qRT-PCR) assay was developed based on the conserved sequence regions of 463 ZIKV NS2B genes. The designed ZIKV qRT-PCR assay was evaluated for its detection limit, strain coverage and cross-reactivity. We further assessed the clinical applicability of qRT-PCR assay for ZIKV RNA detection using a total 18 simulated clinical specimens. The detection limit of the qRT-PCR assay was 11.276 ZIKV RNA copies at the 95% probability level (probit analysis, p<= 0.05). Both Asian and African ZIKV strains were detected by the qRT-PCR assay without cross-reacting with DENV-1, DENV-2, DENV-3, DENV-4, CHIKV, JEV, LGTV, GETV and SINV. The qRT-PCR assay demonstrated a perfect agreement (k = 1.000, P < 0.001) with the reference assay; the sensitivity and specificity of the qRT-PCR assay were 100% (95% CI= 79.6-100) and 100% (95% CI= 43.9-100) respectively. The qRT-PCR assay developed in this study is a useful diagnostic tool for the broad coverage detection and quantification of both the Asian and African ZIKV strains.
Fulltext Seroprevalence of anti-Toxoplasma gondii IgG antibody in patients with schizophrenia

Emelia O, Amal RN, Ruzanna ZZ, Shahida H, Azzubair Z, Tan KS, et al.

Trop Biomed, 2012 Mar;29(1):151-9.
PMID: 22543615 MyJurnal

Schizophrenia is a pervasive neuropsychiatric disease of unknown cause. Previous studies have reported that toxoplasmosis may be a possible cause of schizophrenia. To ascertain possible relationship between Toxoplasma gondii and schizophrenia, a cross sectional study, employing an enzyme-linked immunosorbent assay (ELISA) was performed to study the seroprevalence of anti-T. gondii IgG antibody in schizophrenic patients. Furthermore, demographic data analysis from schizophrenic patients were analysed to associate toxoplasmosis with schizophrenia. A total of 288 serum samples from schizophrenic patients (n=144) and psychiatrically healthy volunteers (n=144) were recruited in this study. Interestingly, a significant result in the serointensity rate of anti-T. gondii IgG antibody (> 60 IU/mL) in schizophrenic patients (61.1%) was demonstrated as compared to psychiatrically healthy volunteers (40.8%) (X² = 4.236, p < 0.050). However, there was no significant difference between the seropositivity rate of anti-T. gondii IgG antibody between the two groups. Analysis from demographic data revealed that the seropositivity rate of anti-T. gondii IgG antibody in schizophrenic patients was significantly associated with age group of more than 40 years old (p=0.007) and between ethnic (p=0.046). Nevertheless, no significant association between seropositivity rate of anti-T. gondii IgG antibody with gender (p=0.897), duration of illness (p=0.344) and family history of schizophrenia (p=0.282) in these patients. Thus, this finding is essential as a preliminary data in Malaysia to establish the association between T. gondii and schizophrenia.
Diastolic dysfunction grading, echocardiographic and electrocardiogram findings in 50 patients with apical hypertrophic cardiomyopathy

Aslannif R, Suraya K, Koh HB, Tey YS, Tan KL, Tham CH, et al.

Med J Malaysia, 2019 12;74(6):521-526.
PMID: 31929479

INTRODUCTION: Apical Hypertrophic Cardiomyopathy (Apical HCM) is an uncommon variant of hypertrophic cardiomyopathy, but it is relatively more common in Asian countries. This is a retrospective, non-randomised, single centre study of patients with Apical HCM focusing on their diastolic dysfunction grading, echocardiographic parameters and electrocardiograms (ECG).
METHODS: All Apical HCM patients coming for clinic visits at the Institut Jantung Negara from September 2017 to September 2018 were included. We assessed their echocardiography images, grade their diastolic function and reviewed their ECG on presentation.
RESULTS: Fifty patient were included, 82% (n=41) were males and 18% (n=9) females. The diastolic function grading of 37 (74%) patients were able to be determined using the updated 2016 American Society of Echocardiography (ASE) diastolic guidelines. Fifty percent (n=25) had the typical ace-ofspades shape left ventricle (LV) appearance in diastole and 12% (n=6) had apical pouch. All patients had T inversion in the anterior leads of their ECG, and only 52% (n=26) fulfilled the ECG left ventricular hypertrophy (LVH) criteria. Majority of our patients presented with symptoms of chest pain (52%, n=26) and dyspnoea (42%, n=21).
CONCLUSION: The updated 2016 ASE guideline makes it easier to evaluate LV diastolic function in most patients with Apical HCM. It also helps in elucidating the aetiology of dyspnoea, based on left atrial pressure. Clinicians should have a high index of suspicion for Apical HCM when faced with deep T inversion on ECG, in addition to a thick LV apex with an aceof- spades appearance during diastole.
Index of suspicion with appropriate timing of CT scan helps prevent missed diagnosis in urologic trauma

Sabrina B, Tan KL, Johann FK, Andre D

Med J Malaysia, 2018 08;73(4):255-256.
PMID: 30121691 MyJurnal

Ureteric and bladder injuries are uncommon, difficult to diagnose and rarely occur in isolation. Diagnosis is often delayed or missed at presentation. Therefore, high clinical suspicion and appropriate timing of computed tomography (CT) are of paramount importance. We report two cases (ureteropelvic junction avulsion and ruptured dome of bladder) whereby the presentations were subtle and would have been missed if not for high clinical suspicion. This article discusses the problems associated with these urologic injuries, as well as how to develop a high index of suspicion based on the pattern of anatomical disruption, mechanism of injury, physiological abnormality and comorbidity.
Fulltext Prevention is better than cure

Andrew Tan KK

Med J Malaysia, 2014 Feb;69(1):1.
PMID: 24814619

No abstract available.
Snake bite in Kelantanese children: a five year experience

Tan KK, Choo KE, Ariffin WA

Toxicon, 1990;28(2):225-30.
PMID: 2339437

The records associated with 83 children from 16 months to 12 years of age who were admitted with snake bite to Kota Bharu General Hospital and University Hospital, Universiti Sains Malaysia over a 5 year period were reviewed. Elapid bites were more common than viper bites while sea-snake bites were not recorded. Symptoms were relatively mild, the common clinical features being pain and local swelling. Antivenom therapy was required in 11 children. Only three of the 11 children developed minor adverse reactions to antivenom. Four of the 83 required ventilatory support for respiratory failure and two children died.
Fulltext Effect of edaravone in diabetes mellitus-induced nephropathy in rats

Varatharajan R, Lim LX, Tan K, Tay CS, Teoh YL, Akhtar SS, et al.

Korean J. Physiol. Pharmacol., 2016 Jul;20(4):333-40.
PMID: 27382349 DOI: 10.4196/kjpp.2016.20.4.333

Edaravone, a synthetic-free radical scavenger, has been reported to reduce ischemia-reperfusion-induced renal injury by improving tubular cell function, and lowering serum creatinine and renal vascular resistance. The present study investigated the effect of edaravone in diabetes mellitus-induced nephropathy in rats. A single administration of streptozotocin (STZ, 55 mg/kg, i.p.) was employed to induce diabetes mellitus in rats. The STZ-administered diabetic rats were allowed for 10 weeks to develop nephropathy. Mean body weight, lipid alteration, renal functional and histopathology were analysed. Diabetic rats developed nephropathy as evidenced by a significant increase in serum creatinine and urea, and marked renal histopathological abnormalities like glomerulosclerosis and tubular cell degeneration. The kidney weight to body weight ratio was increased. Moreover, diabetic rats showed lipid alteration as evidenced by a signifi cant increase in serum triglycerides and decrease in serum high-density lipoproteins. Edaravone (10 mg/kg, i.p., last 4-weeks) treatment markedly prevented the development of nephropathy in diabetic rats by reducing serum creatinine and urea and preventing renal structural abnormalities. In addition, its treatment, without significantly altering the elevated glucose level in diabetic rats, prevented diabetes mellitus-induced lipid alteration by reducing serum triglycerides and increasing serum high-density lipoproteins. Interestingly, the renoprotective effect of edaravone was comparable to that of lisinopril (5 mg/kg, p.o, 4 weeks, standard drug). Edaravone prevented renal structural and functional abnormalities and lipid alteration associated with experimental diabetes mellitus. Edaravone has a potential to prevent nephropathy without showing an anti-diabetic action, implicating its direct renoprotection in diabetic rats.
A South East Asian perspective of neuropsychiatric startle syndromes of latah

Lim TT, Tan K, Eow GB, Bhidayasiri R

Parkinsonism Relat Disord, 2022 Jan 26.
PMID: 35120841 DOI: 10.1016/j.parkreldis.2022.01.013

Latah is a culture-specific syndrome characterized by exaggerated startle response, echolalia, palilalia, echopraxia, coprolalia, forced obedience and involuntary vocalization in response to startle. Latah is stimulus-induced and is associated with behavior and psychiatric features. The aim of this review is to provide a comprehensive description on latah from a regional perspective based on previous literature and clinical experiences and highlight the clinical characteristics of latah from a movement disorders perspective. The pathophysiology of latah is complex and poorly understood although psychological stressors have been implicated. In view of the distressing psychosocial impact of latah, this neuropsychiatric startle syndrome warrants further studies to understand the pathophysiology and identify the appropriate treatments.
Physician counselling practices and decision-making for extremely preterm infants in the Pacific Rim

Martinez AM, Partridge JC, Yu V, Wee Tan K, Yeung CY, Lu JH, et al.

J Paediatr Child Health, 2005 Apr;41(4):209-14.
PMID: 15813876

This study was undertaken to evaluate physician counselling practices and resuscitation decisions for extremely preterm infants in countries of the Pacific Rim. We sought to determine the degree to which physician beliefs, parents' opinion and medical resources influence decision-making for infants at the margin of viability.
Fulltext Mumps encephalomyelitis

Tan KK, Manickam WD, Cardosa MJ

Singapore Med J, 1992 Oct;33(5):525-6.
PMID: 1455285

A 7-year-old Indian girl developed complete paralysis of her lower limbs and acute urinary retention 10 days after suffering from mumps. Encephalomyelitis due to mumps was not suspected initially since it is a rare complication of mumps, although relatively well-documented. However, the preceding history of parotitis and the presence of mumps-specific IgM in both blood and cerebrospinal fluid led to the diagnosis. The initially severe acute neurological deficits resolved completely three months after onset of her illness. Serological investigations were helpful in diagnosing neurological complications of mumps in this case, and especially where there is no preceding parotitis.
Keywords: Mumps, encephalomyelitis, infection, Pulau Pinang, general hospital, Malaysia
Influence of bariatric surgery on weight reduction and control of chronic disease among obese patients in Malaysia

Tan KC, Chang CT, Cheah WK, Vinayak CR, Chan HK

Med J Malaysia, 2019 Jun;74(3):215-218.
PMID: 31256176

INTRODUCTION: This study was designed to determine the influence of bariatric surgery on changes in the body mass index (BMI), and the control of diabetes, hypertension and dyslipidaemia among obese patients in Malaysia.
MATERIALS AND METHODS: This was a retrospective cohort study undertaken at a public tertiary care centre in the state of Perak, Malaysia. Information of obese patients who underwent bariatric surgery was obtained from their medical records. The changes in the BMI, HbA1C, systolic and diastolic blood pressure (SBP and DBP), and lipid levels between three months before and after the surgery were assessed.
RESULTS: The patients (n=106) were mostly Malay (66.0%), had at least one comorbidity (61.3%), and had a mean age of 40.38±11.75 years. Following surgery, the BMI of the patients was found to reduce by 9.78±5.82kg/m2. For the patients who had diabetes (n=24) and hypertension (n=47), their mean HbA1C, SBP and DBP were also shown to reduce significantly by 2.02±2.13%, 17.19±16.97mmHg, and 11.45±12.63mmHg, respectively. Meanwhile, the mean total cholesterol, triglyceride and low-density lipoprotein levels of those who had dyslipidaemia (n=21) were, respectively, lowered by 0.91±1.18mmol/L, 0.69±1.11mmol/L and 0.47±0.52mmol/L.
CONCLUSION: The findings suggest that in addition to weight reduction, bariatric surgery is helpful in improving the diabetes, hypertension and dyslipidaemia control among obese patients. However, a large-scale trial with a control group is required to verify our findings.
Fulltext Effects of culinary treatments on the lipid nutritional quality of fish and shellfish

Tan K, Huang L, Tan K, Lim L, Peng Y, Cheong KL

Food Chem X, 2023 Oct 30;19:100856.
PMID: 37780264 DOI: 10.1016/j.fochx.2023.100856

Coronary heart disease (CHD) is one of the leading causes of death worldwide. Seafood, especially fish and shellfish, is a healthy food that reduces the risk of CHD. In many regions, seafood is consumed cooked to eliminate potentially pathogenic microorganisms. Although there have been many reports of culinary preparations causing changes in the fatty acid profile of fish and shellfish, this information has not been well organized, and most of it is not associated to CHD. Therefore, this study was conducted to study the effect of culinary treatments of seafood on lipid nutritional quality in relation to promotion/prevention of CHD. In this study, fatty acid profiles of fish and shellfish prepared with different culinary preparations were obtained from published literature. Lipid nutritional quality indices related to promoting/preventing CHD were calculated and analyzed to reveal the effects of culinary treatment on the lipid nutritional quality of fish and shellfish in promoting/preventing of CHD. The information in this article is very useful and can fill the knowledge gap of the effects of culinary preparation on the lipid nutritional quality of fish and shellfish. Such information is very useful for guiding consumers to choose better ways to cook fish and shellfish to reduce the risk of CHD.
The impact of climate change on Omega-3 long-chain polyunsaturated fatty acids in bivalves

Tan K, Ransangan J, Tan K, Cheong KL

Crit Rev Food Sci Nutr, 2023 Aug 09.
PMID: 37555502 DOI: 10.1080/10408398.2023.2242943

Omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA) have many health benefits to human. Increasing evidence have shown that climate change reduces the availability of plankton n-3 LC-PUFA to primary consumers which potentially reduces the availability of n-3 LC-PUFA to human. Since marine bivalves are an important source of n-3 LC-PUFA for human beings, and bivalve aquaculture completely depends on phytoplankton in ambient water as food, it is important to understand the impact of climate change on the lipid nutritional quality of bivalves. In this study, fatty acid profile of different bivalves (mussels, oysters, clams, scallops and cockles) from different regions (tropical, subtropical and temperate) and time (before 1990, 1991-1995, 1996-2000, 2001-2005, 2006-2010, 2011-2015, 2016-2020) were extracted from published literature to calculate various lipid nutritional quality indicators. The results of this study revealed that the effects of global warming and declines in aragonite saturation state on the lipid content and lipid indices of bivalves are highly dependent on the geographical region and bivalves. In general, global warming has the largest negative impact on the lipid content and indices of temperate bivalves, including decreasing the PUFA/SFA, EPA + DHA and n-3/n-6. However, global warming has a much smaller negative impact on lipid content and lipid indices in other regions. The declines of aragonite saturation state in seawater promotes the accumulation of lipid content in tropical and subtropical bivalves, but it compromised the PUFA/SFA, EPA + DHA and n-3/n-6 of bivalves in all regions. The findings of this study not only fill the knowledge gap of the impact of climate change on the lipid nutritional quality of bivalves, but also provide guidance for the establishment of bivalve aquaculture and fisheries management plans to mitigate the impact of climate change.

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