Enzyme Linked Immunosorbent Assay (ELISA) is a standard assay that has been used widely to validate the presence of analyte in the solution. With the advancement of ELISA, different strategies have shown and became a suitable immunoassay for a wide range of analytes. Herein, we attempted to provide additional evidence with ELISA, to show its suitability for multi-analyte detection. To demonstrate, three clinically relevant targets have been chosen, which include 16kDa protein from Mycobacterium tuberculosis, human blood clotting Factor IXa and a tumour marker Squamous Cell Carcinoma antigen. Indeed, we adapted the routine steps from the conventional ELISA to validate the occurrence of analytes both in homogeneous and heterogeneous solutions. With the homogeneous and heterogeneous solutions, we could attain the sensitivity of 2, 8 and 1nM for the targets 16kDa protein, FIXa and SSC antigen, respectively. Further, the specific multi-analyte validations were evidenced with the similar sensitivities in the presence of human serum. ELISA assay in this study has proven its applicability for the genuine multiple target validation in the heterogeneous solution, can be followed for other target validations.
Squamous cell carcinoma-related antigen (SCC-Ag), first described by Kato and Torigoe in 1977, has been cited by various workers as a serological marker for some epithelial neoplasms. The most well-studied is its association with carcinoma of the uterine cervix. In January 1989, we embarked on a prospective, multivariate study at the University Hospital, Kuala Lumpur to assess the usefulness of serologically assaying SCC-Ag (using the Abbott RIA diagnostic kit) in our patients with carcinoma of the uterine cervix. We were also interested to ascertain whether SCC-Ag is a 'general' marker for all histological types of cervical carcinoma or specific for squamous carcinoma. From the time of commencement to June 1990, 35 newly-diagnosed and histologically-proven cases were entered into the study. Of these, 4 were keratinising squamous carcinoma, 18 large cell non-keratinising carcinoma, 3 adenosquamous carcinoma, 7 adenocarcinoma and 3 carcinoma-in-situ. Our preliminary results show that all keratinising squamous carcinoma and 1/3 each of large cell non-keratinising carcinoma, adenosquamous carcinoma and carcinoma-in-situ had positive pre-therapy serum SCC-Ag levels (i.e greater than 2 ng/ml, 2 ng/ml being an arbitrarily selected 'cut-off' value). In contrast, no adenocarcinoma was serologically positive. In addition, keratinising squamous carcinoma had the highest mean pre-therapy serum SCC-Ag level. The results imply that serum SCC-Ag is related to the (1) presence of squamous and not glandular differentiation and (2) degree of squamous differentiation.
A method is described for the electrochemical determination of squamous cell carcinoma (SCC) antigen, and by testing the effect of 30 nm gold nanoparticles (GNPs). Three comparative studies were performed in the presence and absence of GNPs, and with agglomerated GNPs. The divalent ion Ca(II) was used to induce a strong agglomeration of GNPs, as confirmed by colorimetry and voltammetry. Herein, colorimetry was used to test the best amount of salt needed to aggregate the GNPs. Despite, voltammetry was used to determine the status of biomolecules on the sensor. The topography of the surface of ZnO-coated interdigitated electrodes was analyzed by using 3D-nano profilometry, scanning electron microscopy, atomic force microscopy and high-power microscopy. The interaction between SCC antigen and antibody trigger vibrations on the sensor and cause dipole moment, which was measured using a picoammeter with a linear sweep from 0 to 2 V at 0.01 V step voltage. The sensitivity level was 10 fM by 3σ calculation for the dispersed GNP-conjugated antigen. This indicates a 100-fold enhancement compared to the condition without GNP conjugation. However, the sensitivity level for agglomerated GNPs conjugated antibody was not significant with 100 fM sensitivity. Specificity was tested for other proteins in serum, namely blood clotting factor IX, C-reactive protein, and serum albumin. The SCC antigen was quantified in spiked serum and gave recoveries that ranged between 80 and 90%. Graphical abstractSchematic representation of SCC (squamous cell carcinoma) antigen determination using divalent ion induced agglomerated GNPs. Sensitivity increment depends on the occurrence of more SCC antigen and antibody binding event via GNPs integration. Notably, lower detection limit was achieved at femto molar with proper orientation of biological molecules.
To assess the diagnostic utility of glypican-3 (GPC-3) in comparison to Hep Par 1 in the diagnosis of liver tumours, a cross-sectional study involving 66 resected liver tumours were tested for the protein expression of these markers by immunohistochemistry using monoclonal antibodies. Of the 66 cases, 26 (39.4%) were hepatocellular carcinoma (HCC), 4 (6.1%) were intrahepatic cholangiocarcinoma and 36 (54.5%) were metastatic tumours. Hep Par 1 and GPC-3 expressions in HCC were 24/26 (92.3%) and 19/26 (73.1%) respectively. In contrast, of non-HCC cases, only 2/40 cases (5.0%) expressed Hep Par 1, including a metastatic colorectal adenocarcinoma and a metastatic gastric adenocarcinoma. GPC-3 was expressed in 3/40 cases (7.5%), i.e. a metastatic adenocarcinoma of unknown origin, a metastatic gastric adenocarcinoma and an intrahepatic cholangiocarcinoma. The sensitivity and specificity for Hep Par 1 were 92.3% and 95% respectively while that of GPC-3 was 73.1% and 92.5% respectively. GPC-3 is a useful marker in the diagnosis of HCC. However it is not superior to Hep Par 1 in its sensitivity and specificity. We recommend that it is utilized together with Hep Par 1 as a panel in the diagnosis of HCC.
Cutaneous metastasis of hepatocellular carcinoma (HCC) is very rare, accounting for less than 0.8% of all known cutaneous metastases and occurring in 2.7-3.4% of HCCs. With less than 50 such cases reported worldwide, most of which were diagnosed histologically on excised lesions, it can only be expected that diagnosis made on cytological features alone would be challenging. We report a case of cutaneous metastasis of HCC diagnosed based on cytological features and confirmed by Hep Par 1 immunopositivity of the cell block material. An 81-year-old man, who was known to have unresectable HCC, presented with a 1-month history of painless, left nasal alae mass. The mass measured 1.5 cm in diameter, and was multilobulated with a central necrosis. Fine needle aspiration of the mass was done. Smears were cellular, comprising of malignant cells in loose clusters and aggregates as well as singly dispersed. The malignant cells displayed moderate nuclear pleomorphism, occasional prominent nucleoli, and intranuclear pseudoinclusion. Cell block material demonstrated the trabeculae pattern of the malignant cells and Hep Par 1 immunopositivity. The final diagnosis of a metastatic cutaneous HCC was made. In conclusion, cutaneous HCC metastasis is rare and should be considered in the differential diagnosis in patients with a history of HCC presenting with suspicious skin lesion. In the right clinical setting, a confident diagnosis can be made in such cases by using the fine needle aspiration technique aided with immunopositivity for Hep Par 1 antibody of the aspirated material.