Biomedical subjects

Jose-Luiz Figueiredo

Publications and source records attributed to Jose-Luiz Figueiredo.

2 recordsLinked to original sources

PubMed2006

Near infrared thoracoscopy of tumoral protease activity for improved detection of peripheral lung cancer.

Improvement in tumor detection using "smart" probes in combination with microcatheter fluorescence thoracoscopy was evaluated in a mouse model. These imaging probes increase in fluorescence intensity after protease activation; cathepsin B is a major activator of the probes used in this study. Lewis lung carcinoma cells were orthotopically implanted in the subpleural lung parenchyma. Two activatable near infrared (NIR) probes with different excitation and emission wavelength were administered intravenously to determine whether wavelength would modulate target to background ratio (TBR). Mice were selectively intubated and thoracoscopy performed. A 0.8 mm outer diameter imaging catheter was used to record simultaneous white-light (anatomic) and NIR (protease expression) images. At both wavelength pairs evaluated (680/700 and 750/780 nm excitation/emission), the intrinsic luminosity differences between tumors and normal lung in uninjected animals was low (p > 0.3 and p = 0.4, respectively and TBR near 1). In mice receiving protease probes IV, tumors were significantly more fluorescent than adjacent lung (p < 0.0005 for 680/700 and p < 0.006 for 750/780) and TBR increased to approximately 9-fold. Confirmatory fluorescence microscopy and immunohistochemistry were similar and revealed that normal lung had very low levels when compared to tumors of cathepsin B and probe fluorescence. In conclusion, protease sensitive imaging probes selective for cathepsin B, imaged with NIR microcatheters, significantly increase the TBR, making small peripheral lung tumors more readily apparent. Such an approach may be a useful adjunct in staging or restaging patients with lung cancer to find minimal disease in the pleural and subpleural space.

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PubMed2006

Fluorescent nanoparticle uptake for brain tumor visualization.

Accurate delineation of tumor margins is vital to the successful surgical resection of brain tumors. We have previously developed a multimodal nanoparticle CLIO-Cy5.5, which is detectable by both magnetic resonance imaging and fluorescence, to assist in intraoperatively visualizing tumor boundaries. Here we examined the accuracy of tumor margin determination of orthotopic tumors implanted in hosts with differing immune responses to the tumor. Using a nonuser-based signal intensity method applied to fluorescent micrographs of 9L gliosarcoma green fluorescent protein (GFP) tumors, mean overestimations of 2 and 24 microm were obtained using Cy5.5 fluorescence, compared to the true tumor margin determined by GFP fluorescence, in nude mice and rats, respectively. To resolve which cells internalized the nanoparticle and to quantitate degree of uptake, tumors were disaggregated and cells were analyzed by flow cytometry and fluorescence microscopy. Nanoparticle uptake was seen in both CD11b+ cells (representing activated microglia and macrophages) and tumor cells in both animal models by both methods. CD11b+ cells were predominantly found at the tumor margin in both hosts, but were more pronounced at the margin in the rat model. Additional metastatic (CT26 colon) and primary (Gli36 glioma) brain tumor models likewise demonstrated that the nanoparticle was internalized both by tumor cells and by host cells. Together, these observations suggest that fluorescent nanoparticles provide an accurate method of tumor margin estimation based on a combination of tumor cell and host cell uptake for primary and metastatic tumors in animal model systems and offer potential for clinical translation.

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