A portable and integrated instrument for cell manipulation by dielectrophoresis.

The physical manipulation of biological cells is a key point in the development of miniaturized systems for point-of-care analyses. Dielectrophoresis (DEP) has been reported by several laboratories as a promising method in biomedical research for label-free cell manipulation without physical contact, by exploiting the dielectric properties of cells suspended in a microfluidic sample, under the action of high-gradient electric fields. In view of a more extended use of DEP phenomena in lab-on-chip devices for point-of-care settings, we have developed a portable instrument, integrating on the same device the microfluidic biochip for cell manipulation and all the laboratory functions (i.e., DEP electric signal generation, microscopic observation of the biological sample under test and image acquisition) that are normally obtained by combining different nonportable standard laboratory instruments. The nonuniform electric field for cell manipulation on the biochip is generated by microelectrodes, patterned on the silicon substrate of microfluidic channels, using standard microfabrication techniques. Numerical modeling was performed to simulate the electric field distribution, quantify the DEP force, and optimize the geometry of the microelectrodes. The developed instrument includes an electronic board, which allows the control of the electric signal applied to electrodes necessary for DEP, and a miniaturized optical microscope system that allows visual inspection and eventually cell counting, as well as image and video recording. The system also includes the control software. The portable and integrated platform described in this work therefore represents a complete and innovative solution of applied research, suitable for many biological applications.

Large size, villous content and distal location are associated with severe dysplasia in colorectal adenomas.

UNLABELLED: Adenomatous polyps are precursor lesions for colorectal carcinoma. The risk of cancer development has been associated with age and size, amount of villous component and high-grade dysplasia of adenomas. The subject-related and adenoma-related risk factors for severely dysplastic lesions were further investigated. PATIENTS AND METHODS: The study was performed in 474 men and 339 women undergoing endoscopic removal at index colonoscopy of 1217 polyps. RESULTS: The male gender, cases aged over 55 and cases examined for rectal bleeding, showed an increased risk of colorectal polyps (odds ratios, OR = 1.95, 5.1 and 2.99, respectively). Adenomas synchronous with hyperplastic polyps of larger diameter (>10 mm) showed an increased risk of severe dysplasia (OR = 6.94). Severe dysplasia occurred more significantly in younger subjects harbouring villous growths (OR = 4.28, p < 0.03) and in larger adenomas (OR = 3.91, p < 0.001). The risk for severe dysplasia in relation to gender, age, multiplicity and location was higher in adenomas of larger diameter and with villous content. Multivariate analysis showed that distal site (p < 0.02), large size (p < 0.001) and villous content (p < 0.001) were the independent risk factors for severe dysplasia. CONCLUSION: Large size, villous content and distal location are associated with severe dysplasia in colorectal adenomas. The risk for severe dysplasia does not appear to be correlated with age.