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Fulltext Neonatal tetanus: a study of five cases in Sandakan, Sabah

Lum SH, Chew MF

Med J Malaysia, 2009 Mar;64(1):80-2.
PMID: 19852330 MyJurnal

This study aims to study the demographics, clinical presentation, treatment and outcome of neonatal tetanus patients managed at Hospital Duchess of Kent from January 1st 2006 to December 31st 2006. Five neonates were studied. All presented with fever, poor sucking and limb stiffness, with a history of unsterile delivery and uncertain maternal tetanus immunity status. All were nursed in a minimal-stimuli environment and were given IV penicillin G, IM tetanus immunoglobulin and sedatives to control spasms. Nutrition and chest physiotherapy were rendered. Three patients required artificial ventilation. Duration of treatment ranged from 25 to 44 days. All survived. Inadequate maternal immunization, unsterile delivery and inappropriate umbilical cord care are major contributing factors of neonatal tetanus in our study. Supportive measures are the mainstay of treatment in our setting with very limited resources.
Fulltext CD133 marks for colorectal adenocarcinoma

Chew MF, Teoh KH, Cheah PL

Malays J Pathol, 2012 Jun;34(1):25-8.
PMID: 22870594 MyJurnal

CD133, a marker which has been advocated to mark colorectal carcinoma "stem or tumour initiating cells" is amongst the frequently studied markers in colorectal cancer. A study was conducted at the Department of Pathology, University of Malaya Medical Centre to determine the expression of CD133 in 56 archived, formalin-fixed, paraffin-embedded colorectal adenocarcinoma in comparison with adjacent benign colorectal epithelium by immunohistochemical staining for CD133 expression. CD133 immunopositivity was determined as staining at the glandular luminal surface or in the intraluminal debris. Expression was semiquantitated for (1) proportion of CD133 immunopositivity in the malignant or adjacent benign colorectal epithelium and (2) intensity of staining. The final score of CD133 immunopositivity was arbitrarily taken as proportion of CD133 immunopositivity multiplied by intensity of staining in both the malignant and adjacent benign colorectal epithelium. CD133 expression was observed in significantly increased frequency in 49 (87.5%) colorectal adenocarcinoma compared with 15 (26.8%) of the adjacent benign colorectal epithelium (p<0.05). In terms of immunopositivity score (proportion of CD133 immunopositivity multiplied by intensity of staining), colorectal adenocarcinoma had a mean arbitrary score of 8.5 which was significantly higher than the mean immunopositivity score of 0.5 of the adjacent benign colorectal epithelium (p<0.05). In addition, the maximum immunopositivity score for the adjacent benign colorectal epithelium was 4, while 38 (67.9%) of colorectal adenocarcinoma had scores >4. This study shows that CD133 is able to mark colorectal adenocarcinoma but it is still unclear at this juncture whether CD133 is indeed a marker for colorectal adenocarcinoma "stem cells".
Fulltext Peptides as Therapeutic Agents for Dengue Virus

Chew MF, Poh KS, Poh CL

Int J Med Sci, 2017;14(13):1342-1359.
PMID: 29200948 DOI: 10.7150/ijms.21875

Dengue is an important global threat caused by dengue virus (DENV) that records an estimated 390 million infections annually. Despite the availability of CYD-TDV as a commercial vaccine, its long-term efficacy against all four dengue virus serotypes remains unsatisfactory. There is therefore an urgent need for the development of antiviral drugs for the treatment of dengue. Peptide was once a neglected choice of medical treatment but it has lately regained interest from the pharmaceutical industry following pioneering advancements in technology. In this review, the design of peptide drugs, antiviral activities and mechanisms of peptides and peptidomimetics (modified peptides) action against dengue virus are discussed. The development of peptides as inhibitors for viral entry, replication and translation is also described, with a focus on the three main targets, namely, the host cell receptors, viral structural proteins and viral non-structural proteins. The antiviral peptides designed based on these approaches may lead to the discovery of novel anti-DENV therapeutics that can treat dengue patients.
Anti-dengue virus serotype 2 activity and mode of action of a novel peptide

Chew MF, Tham HW, Rajik M, Sharifah SH

J Appl Microbiol, 2015 Oct;119(4):1170-80.
PMID: 26248692 DOI: 10.1111/jam.12921

To identify a novel antiviral peptide against dengue virus serotype 2 (DENV-2) by screening a phage display peptide library and to evaluate its in vitro antiviral activity and mode of action.
Fulltext Viral Determinants and Vector Competence of Zika Virus Transmission

Tham HW, Balasubramaniam V, Ooi MK, Chew MF

Front Microbiol, 2018;9:1040.
PMID: 29875751 DOI: 10.3389/fmicb.2018.01040

Zika virus (ZIKV) has emerged as a new global health threat. Since its first discovery in Zika forest in Uganda, this virus has been isolated from several mosquito species, including Aedes aegypti and Aedes albopictus. The geographical distribution of these mosquito species across tropical and subtropical regions has led to several outbreaks, including the recent pandemic in Brazil, followed by the Pacific islands and other areas of North and South America. This has gained attention of the scientific community to elucidate the epidemiology and transmission of ZIKV. Despite its strong attention on clinical aspects for healthcare professionals, the relationships between ZIKV and its principal vectors, A. aegypti and A. albopictus, have not gained substantial interest in the scientific research community. As such, this review aims to summarize the current knowledge on ZIKV tropism and some important mechanisms which may be employed by the virus for effective strategies on viral survival in mosquitoes. In addition, this review identifies the areas of research that should be placed attention to, for which to be exploited for novel mosquito control strategies.
Fulltext Protein-protein interactions between A. aegypti midgut and dengue virus 2: two-hybrid screens using the midgut cDNA library

Tham HW, Balasubramaniam VR, Chew MF, Ahmad H, Hassan SS

J Infect Dev Ctries, 2015 Dec 30;9(12):1338-49.
PMID: 26719940 DOI: 10.3855/jidc.6422

INTRODUCTION: Dengue virus (DENV) is principally transmitted by the Aedes aegypti mosquito. To date, mosquito population control remains the key strategy for reducing the continuing spread of DENV. The focus on the development of new vector control strategies through an understanding of the mosquito-virus relationship is essential, especially targeting the midgut, which is the first mosquito organ exposed to DENV infection.
METHODOLOGY: A cDNA library derived from female adult A. aegypti mosquito midgut cells was established using the switching mechanism at the 5' end of the RNA transcript (SMART), in combination with a highly potent recombination machinery of Saccharomyces cerevisiae. Gal4-based yeast two-hybrid (Y2H) assays were performed against DENV-2 proteins (E, prM, M, and NS1). Mammalian two-hybrid (M2H) and double immunofluorescence assays (IFA) were conducted to validate the authenticity of the three selected interactions.
RESULTS: The cDNA library was of good quality based on its transformation efficiency, cell density, titer, and the percentage of insert size. A total of 36 midgut proteins interacting with DENV-2 proteins were identified, some involved in nucleic acid transcription, oxidoreductase activity, peptidase activity, and ion binding. Positive outcomes were obtained from the three selected interactions validated using M2H and double IFA assays.
CONCLUSIONS: The identified proteins have different biological activities that may aid in the virus replication pathway. Therefore, the midgut cDNA library is a valuable tool for identifying DENV-2 interacting proteins. The positive outcomes of the three selected proteins validated supported the quality of the cDNA library and the robustness of the Y2H mechanisms.
Characteristics of skin cancers among adult patients in an urban Malaysian population

Han WH, Yong SS, Tan LL, Toh YF, Chew MF, Pailoor J, et al.

Australas J Dermatol, 2019 Nov;60(4):e327-e329.
PMID: 31222718 DOI: 10.1111/ajd.13106

There has been a rising incidence of skin cancers among Asians in recent years. We present a retrospective analysis of 106 skin cancers and analysed the demography, clinical subtypes of skin cancers and surgical techniques used for skin cancer treatment. In our population, skin cancers were most frequently basal cell carcinomas and diagnosed among ethnic Chinese patients.
Stability and antiviral activity of SP40 peptide in human serum

Zarif F, Anasir MI, Koh JX, Chew MF, Poh CL

Virus Res, 2021 Oct 02;303:198456.
PMID: 34314773 DOI: 10.1016/j.virusres.2021.198456

Enterovirus A71 (EV-A71) is one of the main causative agents of hand, foot and mouth disease (HFMD). SP40 peptide was previously identified to inhibit EV-A71 strains from genotypes A, B and C. However, the stability and antiviral activity of SP40 peptide in human serum are yet to be established. To address this, we evaluated the stability and anti-EV-A71 activity of SP40 peptide after incubation in 25 % human serum. Reverse-phase high-performance liquid chromatography (RP-HPLC) and liquid chromatography-mass spectrometry (LC/MS) were utilized to evaluate serum stability and cleavage patterns of SP40 peptide after incubation in human serum. Cell protection assay was used to evaluate the anti-EV-A71 activity of SP40 peptide after incubation in human serum and to identify the minimal active sequence of SP40 peptide that retained antiviral activity. The results showed that the SP40 peptide was stable in human serum with 56 % of the full-length SP40 peptide being detected after 48 h incubation in human serum. The SP40 peptide was mainly cleaved by exopeptidases and no endoprotease recognition sites were identified within the SP40 peptide. Cell protection assays revealed that the SP40 peptide retained substantial activity after 24 and 48 h incubation in human serum. Furthermore, the data revealed that three amino acids at the N-terminus and one amino acid at the C-terminus of the SP40 peptide were dispensable for its antiviral activity. Importantly, the four truncated peptides displayed better potency than the full-length SP40 peptide. Overall, this study provided insights into the stability and activity of SP40 peptide in human serum and will facilitate the development of SP40 peptide as an anti-EV-A71 agent.
Fulltext Geraniin extracted from the rind of Nephelium lappaceum binds to dengue virus type-2 envelope protein and inhibits early stage of virus replication

Abdul Ahmad SA, Palanisamy UD, Tejo BA, Chew MF, Tham HW, Syed Hassan S

Virol J, 2017 11 21;14(1):229.
PMID: 29162124 DOI: 10.1186/s12985-017-0895-1

BACKGROUND: The rapid rise and spread in dengue cases, together with the unavailability of safe vaccines and effective antiviral drugs, warrant the need to discover and develop novel anti-dengue treatments. In this study the antiviral activity of geraniin, extracted from the rind of Nephelium lappaceum, against dengue virus type-2 (DENV-2) was investigated.
METHODS: Geraniin was prepared from Nephelium lappaceum rind by reverse phase C-18 column chromatography. Cytotoxicity of geraniin towards Vero cells was evaluated using MTT assay while IC50 value was determined by plaque reduction assay. The mode-of-action of geraniin was characterized using the virucidal, attachment, penetration and the time-of-addition assays'. Docking experiments with geraniin molecule and the DENV envelope (E) protein was also performed. Finally, recombinant E Domain III (rE-DIII) protein was produced to physiologically test the binding of geraniin to DENV-2 E-DIII protein, through ELISA competitive binding assay.
RESULTS: Cytotoxicity assay confirmed that geraniin was not toxic to Vero cells, even at the highest concentration tested. The compound exhibited DENV-2 plaque formation inhibition, with an IC50 of 1.75 μM. We further revealed that geraniin reduced viral infectivity and inhibited DENV-2 from attaching to the cells but had little effect on its penetration. Geraniin was observed to be most effective when added at the early stage of DENV-2 infection. Docking experiments showed that geraniin binds to DENV E protein, specifically at the DIII region, while the ELISA competitive binding assay confirmed geraniin's interaction with rE-DIII with high affinity.
CONCLUSIONS: Geraniin from the rind of Nephelium lappaceum has antiviral activity against DENV-2. It is postulated that the compound inhibits viral attachment by binding to the E-DIII protein and interferes with the initial cell-virus interaction. Our results demonstrate that geraniin has the potential to be developed into an effective antiviral treatment, particularly for early phase dengue viral infection.
Cyclooxygenase-2 (COX2) expression in adenocarcinoma surpasses that of squamous cell carcinoma in the uterine cervix

Marutha Muthu AK, Cheah PL, Koh CC, Chew MF, Toh YF, Looi LM

Malays J Pathol, 2017 Dec;39(3):251-255.
PMID: 29279587 MyJurnal

Over the years, adenocarcinoma (ADC), which has a worse prognosis than squamous cell carcinoma (SCC) of the cervix, has shown an increasing trend. Cyclooxygenase-2 (COX2) expression which has been associated with worse prognosis in several solid cancers was studied for its association with SCC and ADC of the cervix. 35 histologically re-confirmed SCC and 35 ADC were immunohistochemically stained for COX2 using a mouse monoclonal antibody to COX2 (1:100; Dako: Clone CX-294) on a Ventana Benchmark XT. The histoscore was computed as intensity of staining, semi-quantitated on a scale of 0-3 with 0 = negative, 1 = weak, 2 = moderate and 3 = strong staining intensity; multiplied by percentage of immunopositivity on a scale of 0-4 with 0 = <1%, 1 = 1-25%, 2 = 26-50%, 3 = 51-75% and 4 = ≥75% of immunopositive tumour cells. Histoscore 1-3/12 was considered as low and ≥4/12 as high COX2 expression. SCC affected Chinese more than Malays, while Malays had more ADC (p = 0.032). Mean age at presentation of SCC (57.5 years) was about a decade later than ADC at 47.9 years (p = 0.002). 30/35 (85.7%) of SCC and 34/35 (97.1%) of ADC expressed COX2. Histoscores of ADC (median = 4.0, IQR = 3.0-6.0) was significantly higher (p = 0.014) than those of SCC (median = 3.0, IQR = 2.0-3.0). High histoscores (≥4/12) were more frequent in ADC (55.9%) compared with SCC (26.7%) (p = 0.018), implicating COX2, either directly or indirectly, as a possible player in influencing the poorer outcome of ADC compared with SCC.
Fulltext Metastatic pulmonary calcification mimicking pulmonary tuberculosis: A case report

Loh TC, Pang YK, Liam CK, Chew MF, Tan JL

Respirol Case Rep, 2022 Oct;10(10):e01030.
PMID: 36090023 DOI: 10.1002/rcr2.1030

Metastatic pulmonary calcification (MPC) is characterized by deposition of calcium in the normal lung parenchyma secondary to elevation of serum calcium. Most patients are asymptomatic and routine chest radiograph is not sensitive to make the diagnosis. Further imaging is needed such as computed tomography (CT) which typically shows small centrilobular nodules in the upper lobes. We report a case of a 30-year-old woman with end stage kidney disease who was diagnosed with pulmonary tuberculosis which was then revised to metastatic pulmonary calcification. The CT thorax feature for this patient was atypical for metastatic pulmonary calcification where it demonstrated tree-in-bud nodules suggestive of infection. The final diagnosis was made based on bronchoalveolar lavage which was culture-negative for Mycobacterium and transbronchial lung biopsy demonstrating calcium deposition in the interstitium.
Cutaneous manifestations of patients with Human Immunodeficiency Virus (HIV) Infection: A retrospective review of a tertiary referral centre with clinicopathological correlation

Han WH, Yong JY, Yong SS, Faheem NAA, Toh YF, Chew MF, et al.

Australas J Dermatol, 2021 Aug;62(3):286-291.
PMID: 33729571 DOI: 10.1111/ajd.13580

INTRODUCTION: The majority of patients with Human Immunodeficiency Virus (HIV) will have cutaneous manifestation during their disease course. We report the spectrum of cutaneous manifestations and clinicopathological concordance in the diagnosis of skin diseases in patients with HIV.
METHODS: A retrospective review of all cutaneous manifestations of HIV-infected patients with skin biopsy-proven histopathological confirmation, treated in the University of Malaya Medical Centre, from 2016 till 2018, was performed. Clinical characteristics and histopathological correlation of these patients were reviewed.
RESULTS: A total of 38 cases were included where the median age was 40.5 (interquartile range (IQR) 13.3). The median duration of HIV diagnosis to the development of skin disease was 3 years (IQR 7.8). Majority of our patients were male (89.5%, n = 34), and the commonest mode of transmission is men who have sex with men (36.8%, n = 14). Most patients (92.1%, n = 35) had Acquired Immunodeficiency Syndrome when they presented with skin diseases, predominantly non-infectious types (51.4%, n = 19). Commonest skin diseases include eczema (n = 7) and pruritic papular eruption of HIV (n = 6). Papules and plaques were the commonest morphology for both infectious and non-infectious skin diseases. Duration of HIV diagnosis (P = 0.018) and non-compliance to Highly Active Antiretroviral Therapy (HAART) (P = 0.014) were significantly associated with the development of non-infectious skin diseases. Overall, clinicopathological concordance was 84.2% in our centre.
CONCLUSION: A wide spectrum of cutaneous diseases can occur in HIV patients depending on the degree of immunosuppression. skin biopsy along with appropriate stains, and microbiological cultures are important in helping clinicians clinch the right diagnosis.

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