Displaying publications 21 - 40 of 179 in total

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  1. Cheah PL, Looi LM, Teoh KH, Mun KS, Nazarina AR
    Asian Pac J Cancer Prev, 2012;13(2):469-72.
    PMID: 22524808
    The present study was conducted to assess utility of p16(INK4a) immunopositivity as a surrogate marker for genomic integration of high-risk human papillomavirus infection (hrHPV). A total of 29 formalin-fixed, paraffin-embedded cervical low-grade squamous intraepithelial lesions (LSILs), 27 high-grade squamous intraepithelial lesions (HSILs) and 53 invasive squamous cell carcinomas (SCCs), histologically-diagnosed between 1st January 2006 to 31st December 2008 at the University of Malaya Medical Centre were stained for p16(INK4a) (CINtec Histology Kit (REF 9511, mtm laboratories AG, Heidelberg, Germany). Immunopositvity was defined as diffuse staining of the squamous cell cytoplasm and or nucleus (involving > 75% of the intraepithelial lesions or SCCs). Staining of basal and parabasal layers of intraepithelial lesions was pre-requisite. One (3.4%) LSIL, 24 (88.9%) HSIL and 46 (86.8%) SCC were p16(INK4a) immunopositive. All normal squamous epithelium did not express p16(INK4). p16(INK4a) expression was significantly lower (p<0.05) in LSIL compared with HSIL and SCC with no difference in expression between HSIL and SCC.The increased p16(INK4a) immunopositivity in HSIL and SCC appears in line with the integrated existence of the hrHPV and may provide more insightful information on risk of malignant transformation of cervical squamous intraepithelial lesions than mere hrHPV detection.
  2. Looi LM, Cheah PL, Ng MH, Yip CH, Mun KS, Rahman NA
    Asian Pac J Cancer Prev, 2010;11(3):713-6.
    PMID: 21039041
    A study was initiated to explore possible differences in handling telomere attrition in the most common lignant and benign tumours of the breast in Malaysian women. Infiltrating ductal carcinoma (IDC) and fibroadenoma (FA) represented the malignant and benign prototypes respectively. 29 IDC, 28 FA and 22 benign non-lesional control (BNL) breast tissue samples were analysed for telomerase activation using a Telomerase PCR ELISA kit (Boehringer Mannheim). In addition, 23 IDC, 12 FA and 14 BNL were subjected to telomere length determination with a TeloTAGGG Telomere Length Assay Kit (Roche Diagnostic GmbH, Germany), following digestion of genomic DNA by frequently cutting restriction enzymes RsaI and HinfI. Mean telomerase activity in IDC (A450nm=0.3338), but not FA (A450nm=0.0003) was significantly raised (p<0.05) compared with BNL (A450nm=0.0031). Similarly IDC (1.2 kb), but not FA (2.2 kb), showed significant telomere shortening (p<0.05) relative to BNL (2.9 kb). The findings imply that telomere attrition and telomerase activation differ between malignant and benign tumours of the breast and may be important for targeted therapy.
  3. Lee DS, Yoon SY, Looi LM, Kang P, Kang IN, Sivanandan K, et al.
    Breast Cancer Res, 2012;14(2):R66.
    PMID: 22507745
    Germline TP53 mutations cause an increased risk to early-onset breast cancer in Li-Fraumeni syndrome (LFS) families and the majority of carriers identified through breast cancer cohorts have LFS or Li-Fraumeni-like (LFL) features. However, in Asia and in many low resource settings, it is challenging to obtain accurate family history and we, therefore, sought to determine whether the presence of early-onset breast cancer is an appropriate selection criteria for germline TP53 testing.
  4. Looi LM
    Cancer, 1983 Nov 15;52(10):1833-6.
    PMID: 6627203
    Congo-red screening demonstrated intratumor deposits of amyloid in 35 of 53 unselected cases of basal cell carcinoma. Male subjects had a higher amyloid positivity rate than female subjects. The amyloid deposits were permanganate-resistant and located in the stroma between clumps of tumor cells, as well as abutting the advancing front of the neoplasm. Solar elastosis was often observed in the overlying and adjacent subepidermis. The relationship between amyloid positivity and the different histological subtypes of basal cell carcinoma, tumor ulceration, and density of the lymphoplasmacytic stromal infiltrate were also studied. The possibility that amyloid originates from the tumor cells and is a result of tumor apoptosis (degeneration) is discussed.
  5. Cheah PL, Looi LM, Lin HP, Yap SF
    Cancer, 1990 Jan 1;65(1):174-6.
    PMID: 2152851
    In the 7-year period between 1980 and 1987, six cases of childhood primary hepatocellular carcinoma (PHC) were confirmed histologically in our institution. Hepatitis B surface antigen (HBsAg) seropositivity was confirmed in five of the cases, and tissue HBsAg was shown in four of these using the Shikata's orcein stain. An associated maternal HBsAg seropositivity was shown in two of the seropositive children. The youngest seropositive patient who developed PHC was 7 years old. The mother of this patient was also seropositive. These observations support a causal relation between childhood Hepatitis B virus infection and PHC. The importance of vertical or perinatal transmission of HBV in the causation of childhood PHC and the prophylactic role of childhood vaccination is emphasized. Attention is also drawn to the relative short malignant transformation time seen in some of these patients.
  6. Sumithran E, Looi LM
    Cancer, 1985 Sep 1;56(5):1124-7.
    PMID: 2990666
    In West Malaysia, hepatocellular carcinoma (HCC) is common in the Chinese and in the members of the Senoi aboriginal tribe, two racial groups with diametrically opposite life-styles. Certain fundamental differences exist between the liver tumors in the two races. In the Senoi, the tumor occurs in a younger age group and there is a greater male preponderance than in the Chinese. There is also a very close relationship between hepatitis B virus infection, chronic active hepatitis, cirrhosis, liver cell dysplasia, and HCC in the Senoi and the tumors generally present as multiple nodules studding both lobes of the liver. In the Chinese, although a relationship between hepatitis B virus infection, HCC, and cirrhosis exists, this association is not as strong as in the Senoi and the tumors are generally large and solitary. The data suggest that, although the hepatitis B virus is probably an important oncogenic agent in both racial groups, there may be a difference in the pathogenesis of HCC in the two races.
  7. Tan MS, Cheah PL, Chin AV, Looi LM, Chang SW
    Comput Biol Med, 2021 12;139:104947.
    PMID: 34678481 DOI: 10.1016/j.compbiomed.2021.104947
    Alzheimer's Disease (AD) is a neurodegenerative disease that affects cognition and is the most common cause of dementia in the elderly. As the number of elderly individuals increases globally, the incidence and prevalence of AD are expected to increase. At present, AD is diagnosed clinically, according to accepted criteria. The essential elements in the diagnosis of AD include a patients history, a physical examination and neuropsychological testing, in addition to appropriate investigations such as neuroimaging. The omics-based approach is an emerging field of study that may not only aid in the diagnosis of AD but also facilitate the exploration of factors that influence the development of the disease. Omics techniques, including genomics, transcriptomics, proteomics and metabolomics, may reveal the pathways that lead to neuronal death and identify biomolecular markers associated with AD. This will further facilitate an understanding of AD neuropathology. In this review, omics-based approaches that were implemented in studies on AD were assessed from a bioinformatics perspective. Current state-of-the-art statistical and machine learning approaches used in the single omics analysis of AD were compared based on correlations of variants, differential expression, functional analysis and network analysis. This was followed by a review of the approaches used in the integration and analysis of multi-omics of AD. The strengths and limitations of multi-omics analysis methods were explored and the issues and challenges associated with omics studies of AD were highlighted. Lastly, future studies in this area of research were justified.
  8. Cheah PL, Looi LM, Lee GE, Teoh KH, Mun KS, Nazarina AR
    Diagn Pathol, 2011;6:56.
    PMID: 21699710 DOI: 10.1186/1746-1596-6-56
    Endocervicosis in the urinary bladder is a rare benign condition. We present a case in a 37-year-old woman with classical clinical and pathological features of endocervicosis. The unusual observation of endocervical-like mucinous epithelium in continuity with the urothelium in addition to fully developed endocervicosis prompted immunohistochemical profiling of the case using antibodies to cytokeratins (AE1/AE3, CK19, CK7, CK5/6, CK20), HBME-1, estrogen receptor (ER) and progesterone receptor (PR) to assess the relationship of the surface mucinous and endocervicosis glandular epithelia. The surface mucinous epithelium, urothelium and endocervicosis glands were immunopositive for AE1/AE3, CK7 and CK19 while CK20 was only expressed by few urothelial umbrella cells. The surface mucinous epithelium was CK5/6 and HBME-1 immunonegative but showed presence of ER and PR. This was in contrast to the urothelium's expression of CK5/6 but not ER and PR. In comparison, endocervicosis glands expressed HBME-1, unlike the surface mucinous epithelium. The endocervicosis epithelium also demonstrated the expected presence of ER and PR and CK5/6 immunonegativity. The slightly differing immunohistochemical phenotypes of the surface mucinous and morphologically similar endocervicosis glandular epithelium is interesting and requires further clarification to its actual nature. The patient has remained well and without evidence of disease 18-months following transurethral resection of the lesion.
  9. Ahmad Fauzi MF, Wan Ahmad WSHM, Jamaluddin MF, Lee JTH, Khor SY, Looi LM, et al.
    Diagnostics (Basel), 2022 Dec 08;12(12).
    PMID: 36553102 DOI: 10.3390/diagnostics12123093
    Hormone receptor status is determined primarily to identify breast cancer patients who may benefit from hormonal therapy. The current clinical practice for the testing using either Allred score or H-score is still based on laborious manual counting and estimation of the amount and intensity of positively stained cancer cells in immunohistochemistry (IHC)-stained slides. This work integrates cell detection and classification workflow for breast carcinoma estrogen receptor (ER)-IHC-stained images and presents an automated evaluation system. The system first detects all cells within the specific regions and classifies them into negatively, weakly, moderately, and strongly stained, followed by Allred scoring for ER status evaluation. The generated Allred score relies heavily on accurate cell detection and classification and is compared against pathologists' manual estimation. Experiments on 40 whole-slide images show 82.5% agreement on hormonal treatment recommendation, which we believe could be further improved with an advanced learning model and enhancement to address the cases with 0% ER status. This promising system can automate the exhaustive exercise to provide fast and reliable assistance to pathologists and medical personnel. The system has the potential to improve the overall standards of prognostic reporting for cancer patients, benefiting pathologists, patients, and also the public at large.
  10. Tan HL, Ahmad TS, Sankara Kumar C, Khirusman Adnan Y, Looi LM, Gunasagaran J
    EFORT Open Rev, 2024 Feb 01;9(2):129-137.
    PMID: 38306799 DOI: 10.1530/EOR-23-0151
    Superficial acral fibromyxoma, also known as digital fibromyxoma, is a slow-growing, benign, solitary soft tissue tumor. First described in 2001 by Fetsch et al., it is a condition that often occurs in middle-aged individuals. However, it has also been reported across a wide range of ages, ranging from 4 to 86 years, with males more commonly reported. The condition often presents as solitary soft tissue swelling over the periungual or subungual. We present the management experience of the rare presentation of this rare tumor and a detailed review of the past literature on this condition. Detailed management of the condition has been described, along with the outcome after 2 years of follow-up and treatment experience. Our detailed analysis shows that 2 years is the shortest duration of follow-up to rule out recurrence. Hence, most of the cases reported earlier had given the false sense of the recurrence rate of the tumor, which could lead to undertreatment of the condition. The purpose of this article is to allow the readers to understand better the tumor's characteristics with bone involvement and the tumor's diagnostic strategies and treatment options.
  11. Shahrizal TA, Prepageran N, Rahmat O, Mun KS, Looi LM
    Ear Nose Throat J, 2009 Feb;88(2):786-9.
    PMID: 19224479
    Extramedullary plasmacytoma is a rare plasma cell proliferative disorder with a predilection for the head and neck region. Occasionally, it presents as a solitary lesion in the nasal cavity. We report a case of an isolated lesion in the middle turbinate of the right nasal cavity. The lesion was completely excised via an endoscopic approach. We also review the pathology and management of plasmacytomas in general.
  12. Doustjalali SR, Yusof R, Yip CH, Looi LM, Pillay B, Hashim OH
    Electrophoresis, 2004 Jul;25(14):2392-401.
    PMID: 15274022
    We have analyzed unfractionated sera of newly diagnosed patients (n=10) with breast carcinoma (BC), prior to treatment, and patients (n=5) with fibrocystic disease of the breast (FDB) by two-dimensional gel electrophoresis (2-DE) and silver staining. The patients' 2-DE serum protein profiles obtained were then subjected to image analysis and compared to similar data generated from sera of normal healthy female controls (n=10) of the same range of age. The relative expression of alpha1-antichymotrypsin (ACT), clusterin, and complement factor B was significantly higher in all BC patients as compared to normal controls. However, the expression of alpha1-antitrypsin (AAT) in BC patients was apparently lower than that of the controls. Similar differential expression of ACT was detected in the FDB patients. The aberrant expression of the serum acute-phase proteins of patients with BC and FDB was confirmed by competitive enzyme-linked immunosorbent assay (ELISA). Similar altered proteins expression was also observed from immunohistochemical studies of malignant (n=5) and benign (n=5) breast lesions of the respective patients performed using antisera to the aberrantly expressed proteins. However, the malignant breast lesions were instead positively stained for AAT. The differential expression of the serum proteins was apparently abrogated when a six-month follow-up study was performed on nine of the BC patients subsequent to treatment.
  13. Bhoo-Pathy N, Yip CH, Hartman M, Saxena N, Taib NA, Ho GF, et al.
    Eur J Cancer, 2012 May;48(7):982-9.
    PMID: 22366561 DOI: 10.1016/j.ejca.2012.01.034
    Adjuvant! Online is a free web-based tool which predicts 10-year breast cancer outcomes and the efficacy of adjuvant therapy in patients with breast cancer. As its prognostic performance has only been validated in high income Caucasian populations, we validated the model in a middle income Asian setting.
  14. Lau TP, Lian LH, Cheah PL, Looi LM, Roslani AC, Goh KL, et al.
    Eur J Cancer Prev, 2017 11;26(6):506-510.
    PMID: 28059856 DOI: 10.1097/CEJ.0000000000000336
    X-ray repair cross-complementing group 1 (XRCC1) is one of the key components in the base excision repair pathway that repairs erroneous DNA lesions and removes nonbulky base adducts for the maintenance of genome integrity. Studies have revealed that differences in individual DNA repair capacity can impact the interindividual variation in cancer susceptibility, tumour aggressiveness and treatment response. The relationship between XRCC1 and sporadic colorectal cancer (CRC) susceptibility, which is hitherto inconclusive, has been explored in many association studies of different populations. In view of the conflicting findings generated, we aimed to investigate the association between XRCC1 and genetic predisposition to CRC among Malaysians. The present case-control association study was conducted on 130 CRC patients and 212 age-matched healthy controls. The genotyping of XRCC1 Arg194Trp, Arg280His and Arg399Gln single nucleotide polymorphisms was performed with allele-specific real-time PCR approach. This was followed by basic statistical analysis on the single nucleotide polymorphisms and haplotype data obtained. No significant difference in the allele and genotype frequencies was observed between CRC patients and healthy controls (P>0.05). There was also no association observed between XRCC1 haplotypes and CRC (P>0.05). In conclusion, a positive association between XRCC1 gene polymorphisms and CRC risk was not established in our Malaysian population.
  15. Cheah PL, Looi LM, Tan PE, Bosco J, Kuperan P
    Hematol Oncol, 1992 Nov-Dec;10(6):331-7.
    PMID: 1296933
    Cytophagic histiocytic panniculitis (CHP) is a recently recognized entity that frequently poses a perplexing diagnostic problem. Although the classical case presents with a relapsing fever, subcutaneous nodules, pancytopenia and liver dysfunction, most patients have in addition a multitude of other manifestations which confuse the clinical picture. Notwithstanding the variable clinical course, the disease frequently terminates in fatal hemorrhage. Diagnosis is based on histological features. A lobular panniculitis with an infiltrate of cytologically benign cytophagocytic histiocytes in skin nodules is the sine qua non of CHP. Hence, a deep skin biopsy which includes subcutaneous fat is mandatory to establish the diagnosis. Published information regarding this newly described entity remains scarce and we report two cases of CHP, one occurring in a 30-year-old Kadazan man and another in a 17-year-old Chinese woman seen at the University Hospital, Kuala Lumpur. The latter case presented with exudative ascites, an unusual feature, possibly due to intra-abdominal panniculitis. In addition, we record the development of cirrhosis in the same patient.
  16. Cheah PL, Looi LM, Chan LL
    Histopathology, 1996 Jan;28(1):49-54.
    PMID: 8838120
    Wilms' tumour (nephroblastoma) has been associated with chromosomal abnormalities at the 11p13, 11p15 and 16q regions. A study into the possibility of mutations occurring within p53, the ubiquitous adult tumour suppressor gene, in Wilms' tumour was carried out. Thirty-eight cases were studied. Of these 36 were categorised into the favourable histology group and two into the unfavourable histology group based on the National Wilms' Tumour Study criteria. Archival formalin-fixed, paraffin-embedded tissue sections from each case were stained with a polyclonal (AB565:Chemicon) and a monoclonal (DO7:Dako) antibody raised against p53 protein using a peroxidase-labelled streptavidin biotin kit (Dako). 'Cure' (disease-free survival of 60 months or longer) was documented in 39% of cases with favourable histology tumours. Eleven percent in this group succumbed to the disease. Both cases with unfavourable histology died. Four out of 36 (11%) tumours with favourable histology demonstrated weak to moderate staining with both AB565 and DO7 in more than 75% of tumour cells. In contrast, p53 protein expression in unfavourable histology tumours was significantly increased compared with the favourable histology group (P = 0.021) with both cases demonstrating immunopositivity in > 75% of tumour cells when stained with AB565 and DO7. The intensity of staining ranged from moderate to strong in both cases. It appears from this preliminary study that the immunohistochemical expression of p53 protein in Wilms' tumour, presumably a result of mutation in the p53 tumour suppressor gene, correlates with histological classification, histological categorisation being one of the useful features in the prognostic assessment of Wilms' tumours.
  17. Cheah PL, Looi LM, Lin HP
    Histopathology, 1992 Oct;21(4):365-9.
    PMID: 1328018
    Eight cases of clear cell sarcoma of kidney were seen in the Department of Pathology, University Hospital, Kuala Lumpur, Malaysia over the 16-year period from 1973 to 1989. Five of the patients were males. Six patients were Malay, one Chinese and one Indian. The patients' ages ranged from 8 months to 3 years. Clear cell sarcoma was the original diagnosis in two patients while six were diagnosed as blastemal-predominant Wilms' tumours at presentation. Metastases developed in five patients. Metastatic sites included the thoracic vertebra, skull, orbit, humerus, radius, ulna, shoulder, lung and liver. The prolonged survival, of 9 years and 9 months, seen in one patient despite omission of Adriamycin (doxorubicin) from the chemotherapeutic protocol is highlighted. We also emphasise the histological factors which are of help in differentiating clear cell sarcoma from Wilms' tumour.
  18. Peh SC, Looi LM, Pallesen G
    Histopathology, 1997 Mar;30(3):227-33.
    PMID: 9088951
    The Epstein-Barr virus (EBV) has been implicated as a contributing factor in the development of Hodgkin's disease. Western cases of Hodgkin's disease have shown the presence of EBV in Hodgkin and Reed-Sternberg cells in approximately 50%. We studied a total of 100 consecutive cases of Hodgkin's disease from Malaysia, with the aim to elucidate its association with EBV in a multi-ethnic Asian population. Of 34 patients (34%) less than 15 years of age (childhood), 25 had classical Hodgkin's disease (eight nodular sclerosis, 16 mixed cellularity, one lymphocyte depleted) and nine had lymphocyte predominance Hodgkin's disease. Of the 66 from patients aged 15 years and above, 33 had nodular sclerosis, 24 mixed cellularity, two lymphocyte depleted, one unclassifiable and six lymphocyte predominance Hodgkin's disease. The ethnic distribution of classical Hodgkin's disease was: Malay 23, Chinese 32 and Indian 30 (Malay:Chinese:Indian = 1:1.4:1.3), and the ethnic distribution in the 15 cases of lymphocyte predominance Hodgkin's disease was: Malay four, Chinese 10 and Indian one. Taking into account the ethnic distribution of the general population and of hospital admissions, there appears to be a significant predilection of classical Hodgkin's disease cases in ethnic Indian compared to non-Indian patients (chi-squared test, 0.025 > P > 0.01). Eighty-one cases were tested for the presence of EBV by in situ hybridization for EBV encoded RNA, and 57 cases by immunostaining for EBV latent membrane protein 1. In the younger age group, all except one of the 15 cases (nine mixed cellularity, six nodular sclerosis) showed the presence of EBV (93%). In the older age group, EBV was detected (52%) in the following proportion: 6/27 nodular sclerosis, 19/22 mixed cellularity, 1/2 lymphocyte depleted, 1/1 unclassifiable. None of the 14 cases of lymphocyte predominance Hodgkin's disease showed the presence of EBV in the Hodgkin and Reed-Sternberg cells. The findings suggest a strong association of EBV with Hodgkin's disease in Malaysians (41/67, 61%), in particular childhood cases (93%). In adults, the association with EBV is significantly higher in the mixed cellularity subtype (86%) compared with the nodular sclerosis subtype (22%).
  19. Looi LM
    Histopathology, 1981 Nov;5(6):615-22.
    PMID: 7319480
    Nineteen out of 121 consecutive cardiac biopsies from 107 patients were found to contain amyloid deposits on routine Congo red screening. Seventeen were left atrial appendages removed during mitral valvotomy for chronic rheumatic mitral valve disease while the remaining two were right atrial appendages excised during surgical repair of atrial septal defects. The distribution of amyloid deposits within the atria and their tinctorial characteristics are described. The high prevalence of atrial amyloidosis observed could not be attributed to generalized or senile amyloidosis. The possibility that this is a distinctive localized form of amyloidosis secondary to chronic heart disease is discussed.
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