1.The spectrum of elderly myopathies in an Asian population
Shereen Ng ; Kum-Thong Wong ; Khean-Jin Goh
Neurology Asia 2013;18(2):177-181
Myopathies, although presenting more commonly in the younger age group, can occur and contribute
signifi cantly to disability in the elderly. To describe the spectrum of elderly myopathies, we reviewed
52 elderly patients (> 65 years) from the University of Malaya Medical Centre muscle biopsy databank,
constituting 6.8% of 759 adult patients (> 18 years) who underwent muscle biopsy between 1992 and 2012.
Commonest were the infl ammatory myopathies (41/52, 78.8%), of which 43.9% had dermatomyositis;
23.9% polymyositis; 14.6% sporadic inclusion body myositis; 9.8% undifferentiated myositis and 2.4%
overlap myositis. Seven patients (13.4%) had genetic myopathy; 2 muscular dystrophy and 5 chronic
progressive external ophthalmoplegia, while 4 patients (7.7%) had drug-associated myopathy, 3 with
statins. Malignancies were seen in 9.8% of infl ammatory myopathies at diagnosis. Both acquired and
genetic myopathies are seen in elderly Malaysians of all ethnicities and should not be misdiagnosed
as some are potentially treatable and/or associated with malignancy.
2.A prevalence study of single nucleotide polymorphisms in the promoter of the apolipoprotein E gene in different ethnic groups in Malaysia
Raj Poovindran Anada ; Dharmendra Ganesan ; Nerimala Ramahsamay ; Kum Thong Wong
Neurology Asia 2012;17(4):341-346
Background and Objective: The promoter of the apolipoprotein E (APOE) gene is polymorphic at positions
-491A/T, -427C/T and -219G/T. These single nucleotide polymorphisms may alter transcriptional
activity and impact APOE expression due to differential binding of transcription factors. It has been
suggested that the -491 A, -427 C and -219 T alleles are associated with a high risk of developing
Alzheimer’s disease. This study aims to investigate the frequencies of APOE promoter polymorphisms
in three major ethnic groups (Malay, Chinese and Indian) in Malaysia. Method: DNA was extracted
from blood obtained from 290 healthy people (Malay: n= 92; Chinese: n= 105; and Indian: n= 93),
and the promoter region was amplifi ed using PCR and genotyped by direct sequencing. Result: The
Indian group has the lowest frequencies of - 491 A, - 427 C and - 219 T alleles (83.9%, 3.2% and
56.5%, respectively) compared to the Chinese group with the highest frequencies (97.1%, 11.9% and
67.1%, respectively). The frequencies in the Malay group were somewhere in between (94.6%, 8.2%
and 61.4%, respectively). Moreover, for the - 491 and - 427 positions, the frequencies of possible
genotypes viz., AA or AT or TT and CC or CT or TT, respectively, were statistically signifi cant (P <
0.05, Chi- Square Test) between the 3 ethnic groups.
Conclusion: Based on the frequency of APOE promoter polymorphisms alone, the ethnic Indian may
be predisposed to lower risks for AD than the Chinese or Malay.
3.Pathological findings in a mouse model of Japanese encephalitis infected via the footpad
Tzeh Long Fu ; Kien Chai Ong ; Kum Thong Wong
Neurology Asia 2015;20(3):349-354
We have developed and characterised a mouse model of Japanese encephalitis virus (JEV) infection via
footpad inoculation in order to better mimic viral transmission by mosquito bites. Two-week-old and
5-week-old mice consistently developed signs of infection such as ruffled fur, weight loss, hunchback
posture, tremors, mask-like facies and occasionally, hindlimb paralysis at 4 days post infection (dpi)
and 11-13 dpi, respectively. Most of the animals died within 24 to 48 hours following the onset of signs
of infection, with mortalities of 100% and 33.3% in 2-week-old and 5-week-old mice, respectively.
Mild meningitis and variable parenchymal inflammation with formation of microglial nodules, focal
necrosis and neuronophagia, and perivascular cuffing by inflammatory cells were observed in the
caudate nucleus, putamen, thalamus, cerebral cortex, brainstem, and spinal cord. Viral antigens/RNA
were demonstrated by immunohistochemisty and in situ hybridization, respectively, in most of these
areas as well as in the hippocampus and cerebellum, albeit more focally. The pathological findings in
this mouse model were generally similar to human Japanese encephalitis (JE) and other established JE
models but perhaps, compared to other JEV mouse models, it demonstrates lethal encephalitic infection
more consistently. We believe that our mouse model should be useful to study the pathogenesis of JE,
and for testing anti-viral drugs and vaccines
4.Pathological findings in a mouse model of Japanese encephalitis infected via the footpad
Tzeh Long Fu ; Kien Chai Ong ; Kum Thong Wong
Neurology Asia 2015;20(4):349-354
We have developed and characterised a mouse model of Japanese encephalitis virus (JEV) infection via
footpad inoculation in order to better mimic viral transmission by mosquito bites. Two-week-old and
5-week-old mice consistently developed signs of infection such as ruffled fur, weight loss, hunchback
posture, tremors, mask-like facies and occasionally, hindlimb paralysis at 4 days post infection (dpi)
and 11-13 dpi, respectively. Most of the animals died within 24 to 48 hours following the onset of signs
of infection, with mortalities of 100% and 33.3% in 2-week-old and 5-week-old mice, respectively.
Mild meningitis and variable parenchymal inflammation with formation of microglial nodules, focal
necrosis and neuronophagia, and perivascular cuffing by inflammatory cells were observed in the
caudate nucleus, putamen, thalamus, cerebral cortex, brainstem, and spinal cord. Viral antigens/RNA
were demonstrated by immunohistochemisty and in situ hybridization, respectively, in most of these
areas as well as in the hippocampus and cerebellum, albeit more focally. The pathological findings in
this mouse model were generally similar to human Japanese encephalitis (JE) and other established JE
models but perhaps, compared to other JEV mouse models, it demonstrates lethal encephalitic infection
more consistently. We believe that our mouse model should be useful to study the pathogenesis of JE,
and for testing anti-viral drugs and vaccines
Encephalitis, Japanese
;
Virus Diseases
5.Single mitochondrial DNA deletions in chronic progressive external ophthalmoplegia (CPEO) and Kearns-Sayre syndrome (KSS) patients from a multiethnic Asian population
Jia-Woei Chong ; Azlina Ahmad Annuar ; Kum-Thong Wong ; Meow-Keong Thong ; Khean-Jin Goh
Neurology Asia 2014;19(1):27-36
Mitochondrial DNA (mtDNA) deletions are a major cause of chronic progressive external ophthalmoplegia
(CPEO) and Kearns-Sayre syndrome (KSS). We analyzed single mtDNA deletions in 11 CPEO and
one KSS patients by means of Southern blot and long polymerase chain reaction (PCR) assays. The
deletion sizes ranged from 3.4 kb to 6.9 kb whereas the heteroplasmy level varied from 18.8% to
85.5%. Two unique deletions sized 4320 bp and 4717 bp were found. This study represents the first
genetic screen of mtDNA disorders in Malaysia, and it follows the data seen in other published reports
on CPEO and KSS genetic aetiology.
6.The frequency of common mitochondrial DNA mutations in a cohort of Malaysian patients with specifi c mitochondrial encephalomyopathy syndromes
Jia-Woei Chong ; Azlina Ahmad Annuar ; Kum-Thong Wong ; MeowKeong Thong ; Khean-Jin Goh
Neurology Asia 2011;16(4):321-327
A cohort of Malaysian patients with clinico-pathological diagnosis of three specifi c mitochondrial
encephalomyopathy syndromes comprising of mitochondrial encephalomyopathy, lactic acidosis
and stroke-like episodes (MELAS), myoclonus epilepsy with ragged-red fi bers (MERRF) and Leigh
syndrome were studied to determine the frequency of their common mitochondrial DNA mutations. The
‘hot-spot’ point mutations for MELAS, MERRF and Leigh syndrome were screened. In the absence
of common point mutations, screening of large-scale deletions as well as sequencing of tRNALeu and
tRNALys genes were performed. Of 22 patients studied, nine m.3243A>G mutations, four m.8344A>G
mutations, one m.8993T>G mutation and one deletion were identifi ed (65% detection rate). While the
m.3243A>G mutation was closely associated with MELAS, the m.8344A>G was more heterogenous,
being seen in one MERFF, two isolated mitochondrial myopathies and one Leigh syndrome patient.
Screening for m.8993T>G in Leigh syndrome has a low yield as unsurprisingly Leigh syndrome has
considerable genetic heterogeneity.
8.Aetiology of viral central nervous system infection, a Malaysian study
Yean Kong Yong ; Heng Thay Chong ; Kum Thong Wong ; Chong Tin Tan ; Shamala Devi
Neurology Asia 2008;13(1):65-71
Over 100 viruses are known to cause acute viral encephalitis in human. In order to diagnose a viral
central nervous system infection, various laboratory diagnosis methods have been used. In this study,
we examined 220 cerebrospinal fluid samples that were received at the Diagnostic Virology Laboratory
of University Malaya Medical Centre between year 2004 to 2006, by viral isolation, pathogen specific
antibody ELISA, polymerase chain reaction (PCR) and Real-Time PCR. Majority of the samples
were from patients <10 years old. Out of 220 samples, 3 were positive for viral isolation, 27 for
PCR (inclusive for the 3 positive for viral isolation) and 39 for pathogen specific ELISA. The total
positive detection rate of this study was 30%. Herpes virus was the most important aetiologic agent,
responsible for 58% of infection, followed by paramyxovirus (especially measles virus) in 26% of
infection, and 14% by enterovirus. Parvovirus and flavivirus were the other common viruses. Among
the herpes viruses, herpes simplex and cytomegalovirus were the most common.
9.Pathological findings in a mouse model for Coxsackievirus A16 infection
Yuan Teng Hooi ; Kien Chai Ong ; David Perera ; Kum Thong Wong
Neurology Asia 2015;20(3):343-347
Coxsackievirus A16 (CV-A16) is the leading cause of hand-foot-mouth disease (HFMD), which usually
presents as mild and self-limiting symptoms in young children. Rarely, CV-A16 has been reported
to cause severe and fatal neurological complications but little is known about these complications.
In the present study, 1-day and 7-day old mouse models of CV-A16 were developed using a clinical
strain via subcutaneous inoculation. All infected mice exhibited clinical signs of infection, including
reduced mobility, limb weakness and paralysis between 3 to 6 days post-infection. Pathologically,
the main organs involved were the central nervous system (CNS), skeletal muscles and brown fat. In
the CNS, viral antigens as demonstrated by immunohistochemistry, were localized mainly to neurons
in the brain stem and spinal cord, suggesting that CV-A16 is neurotropic although inflammation is
very mild. The skeletal muscles showed necrosis and myositis due to viral infection as evidenced by
the dense viral antigens. Focal viral antigens were also detected in the brown fat. These preliminary
pathological findings indicate that our mouse models can be further developed to be useful models
for pathogenesis studies, and vaccine and anti-viral drug evaluation.
10.Pathological findings in a mouse model for Coxsackievirus A16 infection
Yuan Teng Hooi ; Kien Chai Ong ; David Perera ; Kum Thong Wong
Neurology Asia 2015;20(4):343-347
Coxsackievirus A16 (CV-A16) is the leading cause of hand-foot-mouth disease (HFMD), which usually
presents as mild and self-limiting symptoms in young children. Rarely, CV-A16 has been reported
to cause severe and fatal neurological complications but little is known about these complications.
In the present study, 1-day and 7-day old mouse models of CV-A16 were developed using a clinical
strain via subcutaneous inoculation. All infected mice exhibited clinical signs of infection, including
reduced mobility, limb weakness and paralysis between 3 to 6 days post-infection. Pathologically,
the main organs involved were the central nervous system (CNS), skeletal muscles and brown fat. In
the CNS, viral antigens as demonstrated by immunohistochemistry, were localized mainly to neurons
in the brain stem and spinal cord, suggesting that CV-A16 is neurotropic although inflammation is
very mild. The skeletal muscles showed necrosis and myositis due to viral infection as evidenced by
the dense viral antigens. Focal viral antigens were also detected in the brown fat. These preliminary
pathological findings indicate that our mouse models can be further developed to be useful models
for pathogenesis studies, and vaccine and anti-viral drug evaluation.
Coxsackievirus Infections