MyMedR

Nosocomial infections are a major public health concern worldwide. Early and accurate identification of nosocomial pathogens which are often multidrug resistant is crucial for prompt treatment. Hence, an alternative real-time polymerase chain reaction coupled with high resolution melting-curve analysis (HRMA) was developed for identification of five nosocomial bacteria. This assay targets species-specific regions of each nosocomial bacteria and produced five distinct melt curves with each representing a particular bacterial species. The melting curves were characterized by peaks of 78.8 ± 0.2 °C for Acinetobacter baumannii, 82.7 ± 0.2 °C for Escherichia coli, 86.3 ± 0.3 °C for Klebsiella pneumoniae, 88.8 ± 0.2 °C for Pseudomonas aeruginosa and 74.6 ± 02 °C for methicillin-resistant Staphylococcus aureus. The assay was able to specifically detect the five bacterial species with an overall detection limit of 2 × 10(-2) ng/μL. In conclusion, the HRM assay developed is a simple and rapid method for identification of the selected nosocomial pathogens.

Fulltext Postpartum dietary intakes and food taboos among chinese women attending maternal and child health clinics and Maternity Hospital, Kuala Lumpur

Poh BK, Wong YP, Abdul Karim N

Malays J Nutr, 2005;11(1):1-21-.

MyJurnal

Traditionally, Chinese women adhere to special dietary practices during the month following childbirth. This paper discusses the dietary practices and food taboos practised by Chinese women in Kuala Lumpur. A total of 134 Chinese mothers of children below one year were recruited from three Maternal and Child Health Clinics and Maternity Hospital, Kuala Lumpur. Questionnaires and in-depth interviews were used to obtain information on socioeconomic background, dietary practices, food taboos and cooking methods during the confinement period. Food intake was assessed by multiple 24-hour dietary recall among 34 mothers during their confinement month (zuo yuezi). Body weight and height were measured, and body mass index calculated. Majority of the respondents had secondary school education (77.6%), household income between RM1001 and RM3000 (64%), and were homemakers (48.5%). The women were aged 18-39 years, and 68% were of normal weight. Most women (82%) practised 30 days of confinement, during which they adhered to special dietary practices. The diet was directed at attaining yin-yang (cold-hot) balance, whereby â€œhotâ€ foods were most commonly used and â€œcoldâ€ foods were avoided. Ginger, rice wine and sesame seed oil, considered â€œhotâ€ foods, were used in large amounts in the cooking. Rice, chicken and pork were also consumed in large amounts. Most vegetables and fruits were considered â€œcoldâ€ and were prohibited during confinement. Most mothers drank specially-prepared teas boiled from Chinese herbs. Mean energy intake was 19% below RNI, while mean protein intake was 93% above RNI (NCCFN, 2005). Mean intakes of thiamin, riboflavin and niacin were above 75% of RNI, while vitamins A and C were at half of RNI or less. Mean iron and calcium intakes were at 222% and 67% of RNI, respectively. It is concluded that most Chinese women in Kuala Lumpur do conform to special dietary practices during zuo yuezi.

Study site: three Maternal and Child Health Clinics and Maternity Hospital, Kuala Lumpur

Extranodal NK/T cell lymphoma, nasal type: a rare diagnosis with common nasal presentation

Mohd Ramli SS, Husain S, Wong YP

BMJ Case Rep, 2021 Jun 22;14(6).

PMID: 34158320 DOI: 10.1136/bcr-2020-236436

A 39-year-old man presented with bilateral nasal obstruction for 4 months and associated with hyposmia and foul-smelling nasal discharge. Nasal endoscopy showed irregular mucosa of the nasal cavity with easily bleeding. Nasal biopsy reported as extranodal Natural Killer/T cell lymphoma, nasal type. In-situ hybridisation for Epstein-Barr encoding region was positive. He was treated with six cycles of gemcitabine, oxaliplatin and L-asparaginase and peripheral blood stem cell transplant. After the treatment, he was asymptomatic until 9 months where he had splenic abscess and undergone splenectomy. He was asymptomatic of the disease for 2 years.

Cervical angiomyofibroblastoma: a case report and review of literature

Wong YP, Tan GC, Ng PF

J Obstet Gynaecol, 2017 Jul;37(5):681-682.

PMID: 28604180 DOI: 10.1080/01443615.2017.1281236

Xanthomatous meningioma: A metaplastic or degenerative phenomenon?

Wong YP, Tan GC, Kumar R

Neuropathology, 2018 Dec;38(6):619-623.

PMID: 30187570 DOI: 10.1111/neup.12511

Xanthomatous changes can be observed in various conditions including primary xanthomatosis that is linked to an underlying hypercholesterolemia and more commonly associated with secondary xanthomatous degenerative processes in neoplasm and chronic inflammation. Meningioma with extensive xanthomatous change is exceedingly rare. The presence of cholesterol clefts within this peculiar meningioma subtype has not been described. Herein, we report an unusual case of xanthomatous meningioma in an 83-year-old normolipidemic woman, who presented to us with worsening lower limb weakness and global aphasia. There was increasing evidence to suggest that the presence of xanthomatous changes in long-standing meningioma is merely a sequela of cellular degeneration rather than true metaplastic change as previously hypothesized. Hence, the diagnosis of "xanthomatous meningioma" in the metaplastic category should be revisited and considered as a distinct histological subtype. The possible histogenesis of such intriguing phenomenon is discussed with a review of the literature.

Occult primary breast carcinoma presented as an axillary mass: A Diagnostic Challenge

Wong YP, Tan GC, Muhammad R, Rajadurai P

Malays J Pathol, 2020 Apr;42(1):151-155.

PMID: 32342946

INTRODUCTION: Occult primary breast carcinoma (OBC) manifesting as axillary nodal metastasis without an identifiable breast primary is exceptionally rare. It continues to pose a diagnostic challenge to pathologists. Here, we report a case of OBC with emphasis on the usefulness of immunohistochemistry to determine the primary site of tumour.

CASE REPORT: A 58-year-old female presented with a 3-cm painless right axillary mass. Extensive radiological investigations that include mammography, ultrasonography of the breasts and positron emission tomography (PET) scan failed to conclude the primary site of the tumour. Histological examination of the lymph node revealed loosely cohesive sheets of poorly differentiated malignant cells, without discernible glandular or squamous differentiation. Immunohistochemically, the malignant cells exhibited diffuse immunoreactivity toward pan-cytokeratin and CK7, while leukocyte common antigen, S100 and CK20 were negative. A second panel of immunomarkers was carried out. The malignant cells expressed breast-specific markers (GATA-3, GCDFP-15 and mammaglobin), and were negative for ER, PR and TTF-1 immunohistochemistry. A diagnosis of OBC was rendered.

DISCUSSION: Breast primary must always be considered in the differential diagnosis in patients with sole presentation of axillary lymphadenopathy. The breast-specific immunomarkers play a pivotal role in the diagnosis of ER, PR-negative occult breast cancer.

Construction of a doxycycline inducible lentivirus that expresses stem cell-specific miR-302 cluster

Tan GC, Wong YP, Cui W, Dibb N

Malays J Pathol, 2020 Apr;42(1):91-97.

PMID: 32342936

INTRODUCTION: The polycistronic miR-302 cluster encodes five miRNA genes that have an important role in the regulation of embryonic stem cell function. Studies showed that the miR-302 cluster can reprogram both mouse and human fibroblasts to induced pluripotent stem cells (iPSCs) with high efficiency. The aim of this study was to generate an inducible lentivirus that expresses miR-302 cluster in order to further investigate somatic cell reprogramming by these miRNAs.

MATERIALS AND METHODS: The miR-302 cluster was amplified by polymerase chain reaction technique from human genomic DNA and was ligated into pTRIPz, an inducible lentiviral vector.

RESULTS: MRC5 fibroblasts and HEK293 (human embryonic kidney) cells were infected with pTRIPz-302 cluster lentivirus and the family of 302 miRNAs were strongly expressed in HEK293 cells but lowly expressed in MRC5 fibroblasts. When cultured in hESC conditions, MRC5 cells expressed only low levels of DNMT3B, Nanog, Oct4 and Lin28 and failed to show stem cell induction. The red fluorescent expression seen in the majority of MRC5 cells, indicated that the rate of infection by lentivirus was efficient.

DISCUSSION: The efficiency of reprogramming may be improved perhaps by either using a different cell type or a high expression vector with a different type of promoter.

CD3-positive plasmablastic lymphoma reported in two cases: A potential diagnostic caveat

Wong YP, Masir N, Chew MX

Indian J Pathol Microbiol, 2021 8 4;64(3):579-583.

PMID: 34341278 DOI: 10.4103/IJPM.IJPM_616_20

Plasmablastic lymphoma (PBL) is a rare aggressive subtype of mature large B cell lymphoma involving almost exclusively the extranodal regions particularly the oral cavity, frequently described in immunocompromised patients. PBL is characterized histologically by diffuse proliferation of large neoplastic cells resembling B immunoblasts or plasmablasts. The diagnosis of PBL can be difficult due to its ambiguous histopathological features mimicking most large cell lymphomas and lacking a distinctive immunophenotypic pattern. They typically lack expression of CD20 and CD79a but may express plasma cell marker, CD138. Aberrant immunoexpression of CD3, a T-cell marker in PBL in the absence of other B-cell markers is exceptionally rare, may potentially lead to incorrect interpretation. Herein, we report a case series of CD3-positive PBL of oral cavity in two individuals, which were initially misdiagnosed as high-grade T-cell lymphomas including extranodal NK/T-cell lymphoma, nasal type. Useful distinguishing clinical settings, histomorphological features, immunohistochemistry and molecular expression profiles of PBL are discussed.

Fulltext SARS-CoV-2 Transplacental Transmission: A Rare Occurrence? An Overview of the Protective Role of the Placenta

Wong YP, Tan GC, Khong TY

Int J Mol Sci, 2023 Feb 25;24(5).

PMID: 36901979 DOI: 10.3390/ijms24054550

The outbreak of the coronavirus disease 2019 (COVID-19) pandemic, caused by novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has resulted in a global public health crisis, causing substantial concern especially to the pregnant population. Pregnant women infected with SARS-CoV-2 are at greater risk of devastating pregnancy complications such as premature delivery and stillbirth. Irrespective of the emerging reported cases of neonatal COVID-19, reassuringly, confirmatory evidence of vertical transmission is still lacking. The protective role of the placenta in limiting in utero spread of virus to the developing fetus is intriguing. The short- and long-term impact of maternal COVID-19 infection in the newborn remains an unresolved question. In this review, we explore the recent evidence of SARS-CoV-2 vertical transmission, cell-entry pathways, placental responses towards SARS-CoV-2 infection, and its potential effects on the offspring. We further discuss how the placenta serves as a defensive front against SARS-CoV-2 by exerting various cellular and molecular defense pathways. A better understanding of the placental barrier, immune defense, and modulation strategies involved in restricting transplacental transmission may provide valuable insights for future development of antiviral and immunomodulatory therapies to improve pregnancy outcomes.

Distribution of cord inflammation in cases with clinical suspicion of chorioamnionitis

Wong YP, Tan GC, Khong TY

Malays J Pathol, 2024 Apr;46(1):41-49.

PMID: 38682843

INTRODUCTION: Identification of acute funisitis, a sign of foetal inflammatory response (FIR), is crucial as their presence is associated with ominous neonatal outcomes. Recommendation on which part of umbilical cord should be sampled to facilitate optimal identification of acute funisitis is limited.

METHODS: This is a retrospective cross-sectional study over a seven-month duration recruiting all patients with clinical suspicion of chorioamnionitis and/or maternal intrapartum pyrexia. The distribution and the degree of cord inflammation were assessed. The cases were also evaluated for maternal inflammatory response (MIR) and chorionic vasculitis (CV).

RESULTS: Of the 191 placentas, 88 (46.1%) had some degree of cord inflammation. Forty-nine (55.7%) had a differential in cord inflammation, with distal cord section (n = 38) demonstrating significant greater inflammation than that of proximal cord section (n = 11) (p<0.001). There were 20 cases with phlebitis only and 8 cases demonstrated arteritis only in either proximal or distal cord sections. Increasing magnitude of cord inflammation was significantly associated with increasing severity of MIR and the rate of CV (p<0.001). CV was observed in 25 (24.3%) cases showing absence of cord inflammation, while 12 (13.6%) cases with cord FIR demonstrated no CV.

DISCUSSION: Inflammatory reaction can occur variably throughout the length of the umbilical cord and chorionic plate vessels, with greater inflammation seen in the distal cord section. We affirm the current Amsterdam recommendation of submitting at least two cross sections of the cord representing proximal and distal sites and two sections from placental parenchyma to facilitate the identification of FIR.

Diagnostic potential of rhinovirus C using reverse-transcription loop-mediated isothermal amplification (RT-LAMP)

Wong YP, Tee KK, Chee HY

Int Microbiol, 2024 Dec 02.

PMID: 39623085 DOI: 10.1007/s10123-024-00621-8

Rhinoviruses (RVs), particularly RV-C, frequently cause acute respiratory infections and asthma exacerbations. However, there is a lack of routine detection methods. Thus, this study aims to develop a rapid molecular and differential diagnostic detection method for RV-C using the reverse transcription (RT) loop-mediated isothermal amplification (LAMP) approach. The RT-LAMP assay targeting the 5'UTR region of RV-C genome was optimized by varying the reaction temperature, magnesium sulphate, betaine concentrations, and reaction time. Compared with conventional RT-PCR with a sensitivity of 106 copies of RNA, RT-LAMP demonstrated a significant increase in efficiency and sensitivity with a quantifiable viral load of at least 101 copies of RNA by gel electrophoresis and colour change, and 104 copies of RNA for end-point detection with a turbidimeter for 40 min. The assay is also specific without amplifying RV-A16 and RV-B72 genomic RNA. In the proof-of-concept assay using 30 clinical respiratory samples with known etiological agents, it detected all RV-C isolates, of which its accuracy was confirmed by sequencing. The newly developed RT-LAMP assay demonstrated good analytical sensitivity and specificity toward RV-C. The assay provides an alternative for improved RV-C diagnosis.

The value of umbilical cord insertion site sampling in detecting maternal and/or fetal inflammatory response

Wong YP, Tan GC, Khong TY

APMIS, 2025 Jan;133(1):e13496.

PMID: 39509086 DOI: 10.1111/apm.13496

The 2016 Amsterdam Placental Workshop Group Consensus Statement recommends sampling a block of the placenta close to the umbilical cord insertion site (UCIB) for histopathological evaluation. This piece of placenta at the umbilical cord insertion is presumed to give a better yield of inflammation (if present). We aimed to investigate the utility of the UCIB in the detection of maternal and/or fetal inflammatory responses (MIR and/or FIR), in comparison with the other sections of the placental parenchyma. This is a retrospective cross-sectional study including all placentas with histologic chorioamnionitis. The histopathological slides of placentas were reviewed as per Amsterdam consensus guidelines. Diagnostic performance of UCIB in identifying MIR and/or FIR, relative to the other placental sections, was assessed. UCIB revealed diagnostic sensitivity, specificity, and diagnostic accuracy of 79.2% (95% CI: 74.2-83.6%), 100.0% (95% CI: 95.6-100.0%), and 83.6% (95% CI: 79.5-87.2%), respectively, in the detection of FIR, while showing a low sensitivity of 52.6% (95% CI: 47.5-57.6%) in detecting MIR. In 59 (24.6%) cases, FIR was not seen in the corresponding placental parenchymal sections but was detected in the UCIBs. This study is the first study to confirm that a section from the UCIB is essential for the detection of FIR, which affirms the Amsterdam consensus sampling recommendations.

Fulltext Can we confidently diagnose pilomatricoma with fine needle aspiration cytology?

Wong YP, Masir N, Sharifah NA

Malays J Med Sci, 2015 Jan-Feb;22(1):84-8.

PMID: 25892955 MyJurnal

Pilomatricomas can be confidently diagnosed cytologically due to their characteristic cytomorphological features. However, these lesions are rarely encountered by cytopathologists and thus pose a diagnostic dilemma to even experienced individuals, especially when the lesions are focally sampled. We describe two cases of histologically confirmed pilomatricoma. The first case is of a 13-year-old boy with posterior cervical 'lymphadenopathy', and the second one is of a 12-year-old girl with a lower cheek swelling. Both aspirates comprised predominantly atypical basal-like cells, with prominent nucleoli. 'Ghost cells' were readily identified by cell block in case two, but cell block in case one yielded no diagnostic material. In case two, pilomatricoma was accurately diagnosed pre-operatively. A cytological suspicion of a neoplastic process was raised in case one. Despite being diagnostically challenging, pilomatricoma can be diagnosed with careful observation of two unique cytological features of the lesions: (1) pathognomonic 'ghost cells' and (2) irregular, saw-toothed, loosely cohesive basaloid cells, with prominent nucleoli. The role of thorough sampling of the lesion, with multiple passes of various sites, cannot be overemphasized.

Mismanagement of cat bite wound: lessons to learn

Muthupalaniappen L, Siti Aishah MA, Wong YP, Jamil A

Clin Ter, 2013 May-Jun;164(3):225-7.

PMID: 23868624 DOI: 10.7417/CT.2013.1553

Animal inflicted wounds, left untreated may result in chronic bacterial or fungal infection. Clinical features of these infections may overlap leading to a delay in diagnosis and treatment. We report a case of chronic non-healing cat bite wound treated with several antibiotics without improvement. Later patient developed the classical "sporotrichoid spread" and a presumptive diagnosis of sporotrichosis was made. Laboratory investigation for fungal culture and skin biopsy failed to identify the underlying pathogen. A trial of oral antifungal agent resulted in complete recovery of the lesions implicating fungus as the causative pathogen. Physicians should have a high index of suspicion for fungal infections when managing animal inflicted wounds.

Solid-state fermentation of palm kernel cake with Aspergillus flavus in laterally aerated moving bed bioreactor

Wong YP, Saw HY, Janaun J, Krishnaiah K, Prabhakar A

Appl Biochem Biotechnol, 2011 May;164(2):170-82.

PMID: 21080102 DOI: 10.1007/s12010-010-9124-8

Solid-state fermentation (SSF) was employed to enhance the nutritive values of palm kernel cake (PKC) for poultry feeding. Aspergillus flavus was isolated from local PKC and utilized to increase the mannose content of PKC via the degradation of β-mannan in PKC; evaluation was done for batch SSF in Erlenmeyer flasks and in a novel laterally aerated moving bed (LAMB) bioreactor. The optimum condition for batch SSF in flasks was 110% initial moisture content, initial pH 6.0, 30 °C, 855 μm particle size, and 120 h of fermentation, yielding 90.91 mg mannose g⁻¹ dry PKC (5.9-fold increase). Batch SSF in the LAMB at the optimum condition yielded 79.61 mg mannose g⁻¹ dry PKC (5.5-fold increase) within just 96 h due to better heat and mass transfer when humidified air flowed radially across the PKC bed. In spite of a compromise of 12% reduction in mannose content when compared with the flasks, the LAMB facilitated good heat and mass transfer, and improved the mannose content of PKC in a shorter fermentation period. These attributes are useful for batch production of fermented PKC feed in an industrial scale.

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