Browsing by Author "Ramesh, R."

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    Detection of micrometastasis in LYMPH nodes using reverse transcription polymerase chain reaction (RT-PCR) for Cytokeratin 20 (CK-20): are we under staging rectal cancer
    (The College of Surgeons of Sri Lanka and SAARC Surgical Care Society, 2003) Wijesuriya, S.R.E.; Kuruppuarachchi, K.O.R.; Deen, K.I.; Weerasinghe, A.; Ramesh, R.; Hewavisenthi, J.
    INTRODUCTION: Postoperative adjuvant chemotherapy in rectal cancer is determined by the presence of metastases in lymph nodes. Detection of LYMPH node metastases is routinely performed by light microscopy. Conventional histology may not detect all metastases especially following neoadjuvant therapy (NAT). CK-20 is a cytokeratin known to be specific to colonic epithelium which may help detection of rectal cancer metastases in lymph nodes. OBJECTIVE: To detect micro metastases in lymph nodes in patients with rectal cancer. staged node negative by routine histology. METHODS: Mesenteric lymph nodes from patients who have undergone NAT for rectal cancer were harvested during surgery. Nodes were bisected and one half sent for Haernatoxylin and eosin (H&E) staining and evaluated by a single pathologist, while the other half was examined for CK 20 by RT-PCR. The technique was validated by testing lymph nodes with known metastases and nodes from patients without cancer. 21 lymph nodes from 6 patients (median age 46 years, range 25-55) which were negative for tumour deposits by H&E stain were assessed for micro metastases. RESULTS: All 2 l nodes which were histologically negative for metastases were positive for micro metastases (positive predictive value l 00%) whilst 2 nodes with known metastases were positive for CK-20, 3 nodes from non-cancer patients were negative for CK-20. CONCLUSION: Detection of CK-20 is accurate in identification of micro metastases of rectal cancer to lymph nodes. Assessment of nodes by H&E histology risks under staging lymph node micro metastases in rectal cancer.
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    Phenotypic and genotypic characterization of antibiotic resistance of Listeria monocytogenes isolated from raw milk samples collected from Polonnaruwa, Sri Lanka
    (Emirates Journal of Food and Agriculture, 2022) Harshani, H.B.C.; Ramesh, R.; Halmillawewa, A.P.; Wijendra, W.A.S.
    Listeria monocytogenes is a food-borne pathogen that can cause severe invasive infection called ‘listerosis’ in humans. Development of antibiotic resistance is a major setback in the management of conditions caused by Listeria in both human and veterinary medicine. In this study, antibiotic resistance of fifty L. monocytogenes strains isolated from raw milk samples collected from farms in Polonnaruwa district, Sri Lanka was determined for four commonly used antibiotics; penicillin, ampicillin, streptomycin and tetracycline. The strains were also tested for the presence of selected antibiotic resistant genes (penA, ampC, strA, strB, tetA and tetB). L monocytogenes isolates showed resistance to ampicillin (60%), penicillin (40%) streptomycin (16%) and tetracycline (8%) in diffusion assays. Phenotypic multidrug resistance was exhibited by twenty isolates. The tetracycline resistant gene (tetA) was detected in seven isolates, while tetB was not detected in any. Presence of streptomycin resistant genes (strA or strB) was confirmed in seven isolates. Ampicillin (ampC) and penicillin (penA) resistant genes were not detected in any of the tested isolates. Except from the samples collected from Sungavila area, isolates from other sampling areas showed resistance to at least one of the antibiotics tested, suggesting that raw milk samples are prone to be contaminated with L. monocytogenes strains with different antibiotic resistant profiles. Therefore, necessary hygienic precautions are recommended to avoid any potential public health threats and to safeguard the health of raw milk consumers.