Displaying publications 21 - 40 of 98 in total

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  1. Mun KS, Cheah PL, Baharudin NB, Looi LM
    Malays J Pathol, 2006 Dec;28(2):73-7.
    PMID: 18376794 MyJurnal
    Hepatocellular carcinoma (HCC) is among the ten most common cancers in Malaysian males. As cellular proliferation is an important feature of malignant transformation, we studied the proliferation pattern of normal and benign perineoplastic liver versus hepatocellular carcinoma in an attempt to further understand the tumour transformation process. 39 HCC (21 with accompanying and 18 without cirrhosis) histologically diagnosed at the Department of Pathology, University of Malaya Medical Centre between January 1992 and December 2003 were immunohistochemically studied using a monoclonal antibody to PCNA (Clone PC10: Dako). 20 livers from cases who had succumbed to traumatic injuries served as normal liver controls (NL). PCNA labeling index (PCNA-LI) was determined by counting the number of immunopositive cells in 1000 contiguous HCC, benign cirrhotic perineoplastic liver (BLC), benign perineoplastic non-cirrhotic (BLNC) and NL cells and conversion to a percentage. The PCNA-LI was also expressed as Ojanguren et al's grades. PCNA was expressed in 10% NL, 38.9% BLNC, 76.2% BLC and 71.8% HCC with BLNC, BLC and HCC showing significantly increased (p < 0.05) number of cases which expressed PCNA compared with NL. The number of BLC which expressed PCNA was also significantly increased compared with BLNC. PCNA-LI ranged from 0-2.0% (mean = 0.2%) in NL, 0-2.0% (mean = 0.3%) in BLNC, 0-3.6% (mean = 0.7%) in BLC and 0-53.8% (mean = 7.6%) in HCC with PCNA-LI significantly increased (p < 0.05) only in HCC compared with BLC, BLNC and NL. Accordingly, all NL, BLC and BLNC showed minimal (<5% cells being immunopositive) immunoreactivity on Ojanguren et al's grading system and only HCC demonstrated immunoreactivity which ranged up to grade 3 (75% of cells). From this study, there appears to be a generally increasing trend of proliferative activity from NL to BLNC to BLC and HCC. Nonetheless, BLNC and BLC, like NL, retained low PCNA-LI and only HCC had a significantly increased PCNA-LI compared with the benign categories. This is probably related to the malignant nature of HCC and may reflect the uncontrolled proliferation of the neoplastic hepatocytes.
  2. Mohd Nor Ihsan NS, Abdul Sani SF, Looi LM, Cheah PL, Chiew SF, Pathmanathan D, et al.
    Prog Biophys Mol Biol, 2023 Sep;182:59-74.
    PMID: 37307955 DOI: 10.1016/j.pbiomolbio.2023.06.002
    Amyloidosis is a deleterious condition caused by abnormal amyloid fibril build-up in living tissues. To date, 42 proteins that are linked to amyloid fibrils have been discovered. Amyloid fibril structure variation can affect the severity, progression rate, or clinical symptoms of amyloidosis. Since amyloid fibril build-up is the primary pathological basis for various neurodegenerative illnesses, characterization of these deadly proteins, particularly utilising optical techniques have been a focus. Spectroscopy techniques provide significant non-invasive platforms for the investigation of the structure and conformation of amyloid fibrils, offering a wide spectrum of analyses ranging from nanometric to micrometric size scales. Even though this area of study has been intensively explored, there still remain aspects of amyloid fibrillization that are not fully known, a matter hindering progress in treating and curing amyloidosis. This review aims to provide recent updates and comprehensive information on optical techniques for metabolic and proteomic characterization of β-pleated amyloid fibrils found in human tissue with thorough literature analysis of publications. Raman spectroscopy and SAXS are well established experimental methods for study of structural properties of biomaterials. With suitable models, they offer extended information for valid proteomic analysis under physiologically relevant conditions. This review points to evidence that despite limitations, these techniques are able to provide for the necessary output and proteomics indication in order to extrapolate the aetiology of amyloid fibrils for reliable diagnostic purposes. Our metabolic database may also contribute to elucidating the nature and function of the amyloid proteome in development and clearance of amyloid diseases.
  3. Mohd Nor Ihsan NS, Abdul Sani SF, Looi LM, Pathmanathan D, Cheah PL, Chiew SF, et al.
    PMID: 38113556 DOI: 10.1016/j.saa.2023.123743
    Trace and minor elements play crucial roles in a variety of biological processes, including amyloid fibrils formation. Mechanisms include activation or inhibition of enzymatic reactions, competition between elements and metal proteins for binding positions, also changes to the permeability of cellular membranes. These may influence carcinogenic processes, with trace and minor element concentrations in normal and amyloid tissues potentially aiding in cancer diagnosis and etiology. With the analytical capability of the spectroscopic technique X-ray fluorescence (XRF), this can be used to detect and quantify the presence of elements in amyloid characterization, two of the trace elements known to be associated with amyloid fibrils. In present work, involving samples from a total of 22 subjects, samples of normal and amyloid-containing tissues of heart, kidney, thyroid, and other tissue organs were obtained, analyzed via energy-dispersive X-ray fluorescence (EDXRF). The elemental distribution of potassium (K), calcium (Ca), arsenic (As), and iron (Fe) was examined in both normal and amyloidogenic tissues using perpetual thin slices. In amyloidogenic tissues the levels of K, Ca, and Fe were found to be less than in corresponding normal tissues. Moreover, the presence of As was only observed in amyloidogenic samples; in a few cases in which there was an absence of As, amyloid samples were found to contain Fe. Analysis of arsenic in amyloid plaques has previously been difficult, often producing contradictory results. Using the present EDXRF facility we could distinguish between amyloidogenic and normal samples, with potential correlations in respect of the presence or concentration of specific elements.
  4. 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.
  5. Malik A, Cheah PL, Hilmi IN, Chan SP, Goh KL
    J Dig Dis, 2007 Feb;8(1):58-64.
    PMID: 17261137
    Nonalcoholic fatty liver disease (NAFLD) is increasing rapidly in the Asia-Pacific region. There has been a paucity of studies from the region. The aims of this study were to define the demographic, anthropometric, metabolic and histological characteristics of patients with NAFLD in our local population and to determine independent predictors of severe liver fibrosis.
  6. Mahadeva S, Mahfudz AS, Vijayanathan A, Goh KL, Kulenthran A, Cheah PL
    J Dig Dis, 2013 Nov;14(11):604-10.
    PMID: 23859493 DOI: 10.1111/1751-2980.12088
    To determine the accuracy of transient elastography (TE) and factors associated with discordance between TE and liver histology in patients with non-alcoholic fatty liver disease (NAFLD).
  7. 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.
  8. Looi LM, Cheah PL
    Malays J Pathol, 2009 Jun;31(1):11-6.
    PMID: 19694308 MyJurnal
    Western-style medicine was introduced to Malaya by the Portuguese, Dutch and British between the 1500s and 1800s. Although the earliest pathology laboratories were developed within hospitals towards the end of the 19th Century, histopathology emerged much later than the biochemistry and bacteriology services. The University Departments of Pathology were the pioneers of the renal histopathology diagnostic services. The Department of Pathology, University of Malaya (UM) received its first renal biopsy on 19 May 1968. Hospital Universiti Kebangsaan Malaysia (HUKM) and Hospital Universiti Sains Malaysia (HUSM) started their services in 1979 and 1987 respectively. It is notable that the early services in these University centres caterred for both the university hospitals and the Ministry of Health (MOH) until the mid-1990s when MOH began to develop its own services, pivoted on renal pathologists trained through Fellowship programmes. Currently, key centres in the MOH are Kuala Lumpur Hospital, Sultanah Aminah Hospital Johor Bahru and Malacca Hospital. With the inclusion of renal biopsy interpretation in the Master of Pathology programmes, basic renal histopathology services became widely available throughout the country from 2000. This subsequently filtered out to the private sector as more histopathologists embraced private practice. There is now active continuing professional development in renal histopathology through clinicopathological dicussions, seminars and workshops. Renal research on amyloid nephropathy, minimal change disease, IgA nephropathy, fibrillary glomerulonephritis, lupus nephritis and microwave technology have provided an insight into the patterns of renal pathology and changing criteria for biopsy. More recently, there has been increasing involvement of renal teams in clinical trials, particularly for lupus nephritis and renal transplant modulation.
  9. Looi LM, Cheah PL, Zhao W, Ng MH, Yip CH
    Malays J Pathol, 2006 Dec;28(2):83-6.
    PMID: 18376796 MyJurnal
    Metastasising ability connotes one of the most important life-threatening properties of malignant neoplasms. Recent studies indicate that CD44 proteins, multifunctional cell adhesion molecules which contribute to "homing" of lymphocytes to lymph nodes as well as cell-cell and cell-matrix interactions, are potential markers of tumour progression. However, whether CD44 expression by human tumours contribute to increased metastatic risk remains controversial. In an attempt to clarify its role in breast cancer, we have investigated the correlation between CD44 expression by breast carcinoma and the presence of axillary lymph node metastases. CD44 expression was detected using a standard immunoperoxidase method on formalin-fixed, paraffin-embedded, primary infiltrating ductal breast carcinoma tissues taken from 60 female patients who underwent mastectomy with axillary node clearance. Tumours were graded according to the modified Bloom and Richardson criteria. 62% of patients had histologically-proven lymph node metastasis. 40% of primary cancers exhibited cytoplasmic membrane immunopositivity for CD44. 46% of primary tumours which have metastasied to axillary lymph nodes were CD44 positive whereas 30% of tumours which have not metastasised expressed CD44. CD44 positivity was expressed by 20% of grade 1, 31% grade 2 and 58% grade 3 tumours. Our results suggest that CD44 may have a role in the progression of breast cancer and emphasise the need to investigate its interaction with other mechanisms of cancer advancement.
  10. Looi LM, Ng MH, Cheah PL
    Malays J Pathol, 2007 Jun;29(1):33-5.
    PMID: 19105326 MyJurnal
    The unique ability of tumour cells to proliferate indefinitely is crucial to neoplastic progression as it allows these cells to express the aggressive properties of cancer without the censure of physiological ageing. This is in contrast to normal somatic cells which are subject to a "mitotic clock," a phenomenon that has been linked to telomeric shortening after each round of cell replication, so that eventually the loss of genetic material reaches a critical stage and the cells undergo senescence and cell death. A study was conducted to investigate the role of telomerase, an RNA-containing enzyme that restores the telomere length, in the neoplastic cell immortalization and progression process. Fresh human tissue samples taken from excision specimens received by the Department of Pathology, University of Malaya Medical Centre, were investigated for telomerase activity using a commercial Telomerase PCR-ELISA kit (Boehringer Mannheim). Specimens comprised 33 breast lesions (10 infiltrating breast adenocarcinoma, 13 fibroadenoma and 10 non-neoplastic breast tissue), 27 colonic lesions (17 colonic adenocarcinoma and 10 non-neoplastic colonic mucosa) and 42 cervical lesions (20 cervical carcinoma and 22 non-neoplastic cervical tissues). Telomerase activity was found in 6 (60%) of 10 breast carcinomas, 6 (46%) of 13 fibroadenomas, none of the 10 nonneoplastic breast samples, 3 (17.6%) of 17 colon carcinomas and none of the 10 non-neoplastic colonic mucosal samples, 12 (60%) of 20 cervical carcinoma and 3 (13.6%) of 22 non-neoplastic cervical samples. 5/10 (50%) Stage I, 4/7 (57%) Stage II, 2/2 (100%) Stage III and 1/1 (100%) Stage IV cervical carcinomas showed telomerase activity. These findings support a contributory role for telomerase in tumourigenesis with activation occurring from neoplastic transformation and increasing with tumour progression.
  11. Looi LM, Cheah PL
    Malays J Pathol, 1998 Jun;20(1):19-23.
    PMID: 10879259
    Eighty-six infiltrating ductal carcinoma of breast were studied by the standard avidin-biotin complex immunoperoxidase method on formalin-fixed, paraffin-embedded tissue sections, for oestrogen receptor (ER) protein and c-erbB-2 oncoprotein expression. They were categorized according to the modified Bloom and Richardson criteria into three histological grades. 21% tumours were ER positive while 44% were c-erbB-2 positive. Of ER positive tumours, 33.3% were c-erbB-2 positive whereas the c-erbB-2 positivity rate was much higher (47.1%) in ER negative tumours. Only 16% of c-erbB-2 positive tumours were ER positive while 25% of c-erbB-2 negative tumours were ER positive. This negative relationship between ER and c-erbB-2 expression was statistically significant (Mc Nemar's test, p < 0.005). The ER positivity rate did not vary significantly with histological grade. However, c-erbB-2 overexpression was significantly more prevalent in grade III tumours compared with grade I and II tumours (Chi-square test, p < 0.005). Since the c-erbB-2 oncogene has extensive structural homology to the epidermal growth factor receptor (EGFR) gene, we expect that c-erbB-2 oncoprotein would share functional similarities with EGFR leading to both loss of oestrogen receptor and poor prognosis in breast cancer. Its overexpression can be expected to relate to more aggressive tumour proliferation and may explain its correlation with high histological grade, a known indicator of aggressive cancer behaviour. As there is no indication that ER protein activity contributes to advancement in histological grade, it would appear that cellular dedifferentiation precedes ER loss during malignant transformation. It has been mooted that ER positive breast cancers which also show c-erbB-2 oncoprotein overexpression have a poorer response to hormonal therapy. The use of this parameter in the routine assessment of breast cancer patients may identify subsets of patients for more aggressive therapy.
  12. Looi LM, Cheah PL
    Hum Pathol, 1997 Jul;28(7):847-9.
    PMID: 9224755
    A retrospective study was conducted to investigate whether there was a correlation between the histological pattern of renal amyloidosis, the chemical type of amyloid protein involved and the clinical presentation. Eighteen consecutive cases of systemic amyloidosis that had renal biopsies processed and examined histopathologically at the Department of Pathology, Faculty of Medicine, University of Malaya, Kuala Lumpur were reviewed. The age range of patients was 25 to 64 yrs (mean, 46 yrs). The male:female ratio was 2.6:1. Three patients were Malay, 9 Chinese, 3 Indian, 1 Indonesian, 1 Iban, and 1 Bisaya. According to the predominant site of amyloid deposition, 14 cases showed a glomerular pattern and 4 a vascular pattern. 8 cases were designated as 2 anti-human amyloid-A (AA) amyloidosis on the basis of permanganate-sensitivity and immunoreactivity of deposits with anti-human AA protein antibody. Ten cases contained deposits that were permanganate-resistant and nonimmunoreactive for AA protein and were designated as AL in type. The histomorphologic pattern of renal amyloidosis did not provide a reliable means of differentiating AA from AL amyloidosis. The glomerular pattern tended to present with renal manifestations such as nephrotic syndrome and chronic renal failure, whereas the vascular pattern tended to present with nonrenal manifestations such as diarrhoea. These findings may have a bearing on the pathophysiology of amyloidosis and provide clues to appropriate management.
  13. Looi LM, Yap SF, Cheah PL
    Ann Acad Med Singap, 1997 Nov;26(6):750-3.
    PMID: 9522973
    Fresh frozen neoplastic tissues from 70 infiltrating ductal breast carcinomas were analysed for cytosolic oestrogen receptor (ER) protein content using a solid phase enzyme immunoassay (EIA) method based on a "sandwich" principle (Abbott ER-EIA monoclonal). Formalin-fixed, paraffin-embedded sections from the same carcinomas were examined for nuclear immunoreactivity against a monoclonal antibody for ER protein (Dako) using the standard avidin-biotin complex immunoperoxidase (IP) method after microwave antigen retrieval. The degree of ER positivity by IP was also scored according to a visual estimation of the percentage of cells expressing immunopositivity and the intensity of staining. Twenty-eight (40%) of the carcinomas were ER-positive by EIA and 34 (48.6%) were positive by IP. Twenty-five (35.7%) were ER-positive and 33 (47.1%) were ER-negative by both methods. Nine (12.9%) were ER-negative by EIA but were positive by IP, this discrepancy being ascribed to sampling inadequacy for EIA. However, 3 (4.3%) tumours were ER-positive by EIA and negative by IP. This discrepancy may be variously due to inadequate antigen retrieval, faulty technique and the possibility that the two methods do not measure identical ER proteins. IP appears to have an advantage over EIA in that it has a higher pick-up rate, does not require fresh tissue and can be applied to archival material. However, to reduce false negative estimations, it may be necessary to run IP staining using more than one ER antibody. Standardisation of the IP method for ER is desirable before this method is to be widely adopted in Malaysian laboratories. Quantitation of ER positivity by IP scoring correlated poorly with actual cytosolic levels. Caution should be exercised in attaching patient management value to visual IP scoring.
  14. Looi LM, Cheah PL, Yap SF
    Malays J Pathol, 1997 Jun;19(1):35-9.
    PMID: 10879240
    One hundred and twelve infiltrating ductal carcinoma of breast were studied by the standard avidinbiotin complex immunoperoxidase method on formalin-fixed, paraffin-embedded tissue sections, using a monoclonal antibody to c-erbB-2 oncoprotein. The same tumours were assessed and scored according to the Bloom and Richardson criteria into three histological grades. The distribution of tumours according to grade were: 8 Grade I, 34 Grade II and 70 Grade III. Forty-three (38.4%) tumours showed positive membrane staining for c-erbB-2 oncoprotein. These comprised 7 Grade II and 36 Grade III tumours with c-erbB-2 immunopositivity rates of 20.6% and 51.4% respectively. The oncoprotein was not expressed by Grade I tumours. This study shows a good correlation between c-erbB-2 expression and histological grade, a known prognostic indicator of invasive breast carcinoma. Because the c-erbB-2 oncogene has extensive structural homology to the epidermal growth factor receptor gene, its overexpression can be expected to result in more aggressive tumour behaviour. While it may be regarded as another indicator of poor prognosis breast cancers, its value in the selection of carcinomas less responsive to hormonal therapy and those more suitable for immunotherapy than chemotherapy has been mooted but remains to be clarified.
  15. Looi LM, Cheah PL
    Malays J Pathol, 1992 Dec;14(2):69-76.
    PMID: 1304627
    In situ hybridisation (ISH) is based on the complementary pairing of labelled DNA or RNA probes with normal or abnormal nucleic acid sequences in intact chromosomes, cells or tissue sections. Compared with other molecular biology techniques applicable to anatomical pathology, ISH enjoys better rapport with histopathologists because of its similarity to immunohistochemistry. It has the unique advantage over other molecular biology techniques--largely based on probe hybridisation with nucleic acid extracted from homogenised tissue samples--of allowing localisation and visualisation of target nucleic acid sequences within morphologically identifiable cells or cellular structures. Probes for ISH may bear radioactive or non-radioactive labels. Isotopic probes (3H, 32P, 35S, 125I) are generally more sensitive than non-isotopic ones but are less stable, require longer processing times and stringent disposal methods. Numerous non-isotopic labels have been used; of these biotin and digoxigenin are the reporters of choice. Optimised non-isotopic systems of equivalent sensitivity to those which use radioactive-labelled probes have been described. In ISH, finding the optimal balance between good morphological preservation of cells and strong hybridisation signals is crucial. Tissue fixation and retention of cytoskeletal structures, unfortunately, impede diffusion of probes into tissues. ISH sensitivity is also influenced by inherent properties of the probe and hybridisation conditions. Although ISH is largely a research tool, it is already making strong inroads into diagnostic histopathology. It has been applied for the detection of various infective agents particularly CMV, HPV, HIV, JC virus, B19 parvovirus, HSV-1, EBV, HBV, hepatitis delta virus, Chlamydia trachomatis, salmonella and mycoplasma in tissue sections.(ABSTRACT TRUNCATED AT 250 WORDS)
  16. Looi LM, Azura WW, Cheah PL, Ng MH
    Pathology, 2001 Aug;33(3):283-6.
    PMID: 11523925
    This investigation was carried out to gain insight into the prevalence of pS2 expression in invasive ductal breast carcinoma in the Malaysian population and its correlation with oestrogen receptor (ER) protein expression and tumour aggressiveness. Seventy consecutive infiltrating ductal breast carcinomas treated with mastectomy and axillary lymph node clearance were investigated, using the standard avidin-biotin complex immunoperoxidase method with microwave antigen retrieval and commercial monoclonal antibodies (Dako), for expression of pS2 and human ER. This was correlated against histological grade (modified Bloom and Richardson) and the presence of axillary lymph node metastasis of these carcinomas. Four (5.7%) were grade 1, 40 (57.1%) grade 2 and 26 (37.1%) grade 3 tumours. A total of 45 (64%) showed histological evidence of axillary lymph node metastasis. Forty (57%) were ER-positive, while 31 (44%) were pS2-positive. There was a statistically significant correlation between pS2 and ER expressions (chi2-test with Yates correction: P<0.005). There was no correlation between pS2 expression and histological grade (P>0.1) and the presence of lymph node metastasis (P>0.1). Our findings support the views that pS2 may be a co-marker of endocrine responsiveness in invasive breast cancer and that it does not influence breast cancer biology in terms of potential for metastatic spread.
  17. Looi LM, Cheah PL, Lin HP
    Pathology, 1992 Jan;24(1):34-6.
    PMID: 1374551
    Clear cell sarcoma of kidney (CCSK) is a rare but distinct tumor of childhood frequently confused with Wilms' tumor (nephroblastoma). It has a characteristic histology, a marked predilection for metastasis to bone, and an aggressive clinical course with a high relapse rate in spite of surgical excision, chemotherapy and radiotherapy. We report the first histologically proven CCSK in a Malaysian patient. This was an 8-mth-old Malay boy who was clinically diagnosed to have stage I Wilms' tumor. Despite treatment, he developed multiple metastases 10 mths after initial presentation and died soon after. Emphasis is placed on recognizing this entity in view of (1) its naturally aggressive behaviour and (2) the prospect of improving prognosis with currently recommended intensified chemotherapeutic regimes. Its immunohistochemical profile of vimentin-positivity and negativity for epithelial membrane antigen, cytokeratin and Factor-8 related antigen is more in favour of a mesenchymal or glomerular origin than a tubular or vascular origin.
  18. Looi LM, Cheah PL
    Pathology, 1993 Apr;25(2):106-9.
    PMID: 8396229
    This study explores immunohistochemical characteristics that may be of diagnostic value in differentiating clear cell sarcoma of the kidney (CCSK) from Wilms' tumor (WT) and may provide some insight into the histogenesis of CCSK. Formalin-fixed, paraffin-embedded sections of 8 CCSK and 9 WT were stained, using the standard avidin-biotin peroxidase complex method, for vimentin (VIM), Factor-8 related antigen (F8A), epithelial membrane antigen (EMA), desmin (DES), S-100 protein and Mac 387. CCSK cells consistently exhibited moderate to strong diffuse cytoplasmic positivity for VIM and were negative for F8A, EMA, DES, S-100 and Mac 387. In contrast, only patchy groups of stromal cells and primitive glomeruloid structures in WT exhibited VIM-positivity. Blastemal cells were VIM-negative. Stromal cells with rhabdomyomatous differentiation exhibited cytoplasmic positivity for DES. Epithelial cells of maturing tubular structures showed EMA-positivity whereas immature tubular structures were EMA-negative. Neither blastemal, stromal nor epithelial elements in WT were positive for F8A, S-100 or Mac 387. Podocytes and mesangial cells of glomeruli in 3 mid-trimester human abortuses (controls) exhibited moderate to strong VIM-positivity. The importance of differentiating CCSK from WT has been repeatedly emphasized because of its poorer prognosis and the necessity of adding Adriamycin to the chemotherapeutic regime. The consistent VIM-positivity of CCSK cells can be a useful feature in differentiating it from "blastemal-predominant" WT, with which it is often confused. Although vimentin expression by CCSK cells is consistent with a mesenchymal character, the possibility of a histogenetic link with glomerular podocytes or mesangial cells should also be considered.
  19. Looi LM, Zubaidah Z, Cheah PL, Cheong SK, Gudum HR, Iekhsan O, et al.
    Malays J Pathol, 2004 Jun;26(1):13-27.
    PMID: 16190103
    Cancer is a major morbidity and mortality concern in Malaysia. Based on National Cancer Registry data, the Malaysian population is estimated to bear a cancer burden of about 40,000 new cases per year, and a cumulative lifetime risk of about 1:4. Cancer research in Malaysia has to consider needs relevant to our population, and resources constraints. Hence, funding bodies prioritise cancers of high prevalence, unique to our community and posing specific clinical problems. Cancer diagnosis is crucial to cancer management. While cancer diagnosis research largely aims at improvements in diagnostic information towards more appropriate therapy, it also impacts upon policy development and other areas of cancer management. The scope of cancer diagnosis upon which this paper is based, and their possible impact on other R&D areas, has been broadly categorized into: (1) identification of aetiological agents and their linkages to the development of precancer and cancer (impact on policy development, cancer prevention and treatment), (2) cancer biology and pathogenesis (impact on cancer prevention, treatment strategies and product development), (3) improvements in accuracy, sensitivity and specificity in cancer detection, monitoring and classification (impact on technology development) and (4) prognostic and predictive parameters (impact on treatment strategies). This paper is based on data collected by the Working Group on Cancer Diagnosis Research for the First National Conference on Cancer Research Coordination in April 2004. Data was collated from the databases of Institutions/Universities where the authors are employed, the Ministry of Science, Technology and Innovation (MOSTI) and targeted survey feedback from key cancer researchers. Under the 7th Malaysia Plan, 76 cancer projects were funded through the Intensified Research in Priority Areas (IRPA) scheme of MOSTI, amounting to almost RM15 million of grant money. 47(61.8%) of these projects were substantially in cancer diagnosis, accounting for 65.6% (RM 9.7 million) of cancer project funds. The 8th Malaysia Plan saw a change in research strategy. The IRPA agency fielded several top-down projects which encouraged a multicentre and multidisciplinary approach. This resulted in larger funding per project i.e. RM32 million for 49 projects. There was also a surge of interest in drug development and natural products. Because of this shift in direction, cancer diagnosis projects constituted only 51% of IRPA-funded cancer projects. Nonetheless funding for cancer diagnosis research has exceeded that of the 7th Malaysia Plan, being RM12.5 million by March 2004. The majority of such research is carried out at the Universities, engaging a large number of young scientists and postgraduate students (51 MSc and 21 PhD). A lot of research findings presented at scientific meetings have not yet been published and there is a glaring shortage of patents and commercialization of research findings (such as creation of test kits). Because diagnosis is very much a part of clinical practice, many researchers felt satisfied and confident that their work will be translated into practice and will significantly improve diagnostic services in Malaysia. National guidelines and consensus development on at least three malignancies i.e. breast cancer, oral cancer and lymphoma, have substantial basis in local R&D work. Problems encountered in research included (1) insufficient funding to realize research objectives, (2) lack of local expertise (most research assistants are inexperienced BSc graduates with no or minimal research experience), (3) inadequate technical support from vendors during equipment failure, (4) inexperienced Institutional development units to assist in product development, (5) lack of venture capital for commercialization of findings, and (6) inadequate incentives to undertake research. Researchers pointed out that plans to promote research should include the establishment of (1) regional and national cancer tissue banks, (2) a National Cancer Research Institute, (3) a dedicated cancer research fund, (4) a registry of cancer researchers, (5) national research coordinators, (6) improved coverage by the National Cancer Registry, (7) more international collaboration, (8) a better career structure for researchers, (9) improved Institutional support for product realization, and (10) better recognition for cancer researchers.
  20. 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.
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