Gianfranco Canti

Fluorescence molecular tomography (FMT) is quite demanding in terms of acquisition/computational times due to the huge amount of data. Different research groups have proposed compression approaches regarding both illumination (wide field structured light instead of raster point scanning) and detection (compression of the acquired images). The authors have previously proposed a fast FMT reconstruction method based on the combination of a multiple-view approach with a full compression scheme. This method had been successfully tested on a cylindrical phantom and is being generalized in this paper to samples of arbitrary shape. The devised procedure and algorithms have been tested on an ex-vivo mouse.

The 14;18 chromosome translocation, characteristic of most human follicular B-cell lymphomas, juxtaposes the bcl-2 gene with the IgH locus, creating a bcl-2/IgH hybrid gene. By mechanisms that are still under investigation, this event increases the cellular levels of the bcl-2 mRNA and thereby induces an overproduction of the antiapoptotic BCL-2 protein which is likely responsible for neoplastic transformation. In an effort to identify potential upregulators of bcl-2 activity in t(14;18) cells, we found, by strand-specific RT-PCR, a bcl-2 antisense transcript that is present in the t(14;18) DOHH2 and SU-DHL-4 but not in the t(14;18)-negative Raji and Jurkat lymphoid cell lines, and thus appears to be dependent on the bcl-2/IgH fusion. This antisense transcript is a hybrid bc1-2/IgH RNA, that originates in the IgH locus, encompasses the t(14;18) fusion site and spans at least the complete 3' UTR region of the bcl-2 mRNA. To achieve some insight into its biological function, we treated the t(14;18) DOHH2 cell line with oligonucleotides (ODNs) by specifically targeting the bc1-2/IgH antisense strand. These ODNs lowered bcl-2 gene expression, inhibited neoplastic cell growth by inducing apoptosis. We would like to propose the hypothesis that the bc1-2/IgH antisense transcript may contribute, by an unknown mechanism, to upregulation of bcl-2 gene expression in t(14;18) cells. The possibility has been considered that the hybrid antisense transcript mask AU-rich motifs present in the 3' UTR of the bcl-2 mRNA characterized in other genes as mRNA destabilizing elements.

Most human follicular B-cell lymphomas are associated with t(14;18) chromosome translocation that joins the bcl-2 gene with the IgH locus. This hybrid gene causes upregulation of BCL-2 protein expression, endowing cells with survival advantage. Although early BCL-2 overexpression is definitely responsible for immortalization/transformation, its exact role in the overt transformation as well as in the maintenance of the tumor phenotype is not known. The capacity of oligodeoxynucleotides (ODN) to modulate gene expression specifically has been exploited to downregulate the overexpression of BCL-2 protein in the SU-DHL-4 human follicular B-cell lymphoma line by the use of sense ODN or antisense ODN or antisense ODN designed to encompass the unique nucleotide sequence in the fusion region of the hybrid transcript. The specific downregulation of the bcl-2 transcript and of the relevant BCL-2 protein in the treated cells activated programed cell death and inhibited growing cells. The antitumor activity was restricted to the DHL-4 cell line carrying the specific nucleotide sequence at the bcl-2/IgH joining region. Thus, DHL-4 lymphoma cells derived from the acute phase of human follicular B-cell lymphoma, although endowed with additional activated oncogenes, were growth inhibited by bcl-2 downregulation with additional activated oncogenes, were growth inhibited by bcl-2 downregulation in a genetically restricted fashion. The biological activity was exerted exclusively by ODNs synthesized in the sense orientation. The sense ODNs have been proposed to anneal the hybrid bcl-2/IgH antisense RNA as identified in this study.

The action spectrum of disulfonated aluminum phthalocyanine (AIS2-Pc) as a photosensitizer for photodynamic therapy (PDT) was evaluated in vivo from 640 to 710 nm on two murine tumors with different biological properties. Mice bearing MS-2 fibrosarcoma and mice bearing the pigmented tumor B16 melanoma were injected with 5 mg/kg of AIS2Pc and irradiated with a light dose of 50 mW for 10 min for the MS-2 fibrosarcoma and of 100 mW for 10 min for the B16 melanoma. The action spectrum for both tumors presents a red shift with respect to the absorption spectrum of AIS2Pc in saline. The effectiveness is limited for short wavelengths (less than or equal to 655 nm for MS-2 and less than or equal to 660 for B16), whereas it increases at longer wavelengths and reaches its maximum at a peak (672 nm). For wavelengths beyond 672 nm the photodynamic activity remains up to 710 nm despite the significant decrease in absorption. The results obtained for both murine tumors seem therefore to indicate that an appreciable modification of the absorption spectrum takes place when AIS2Pc is incorporated into tissues following systematic administration.

High peak-power nanosecond laser pulses generated by excimer-pumped dye lasers are utilized to induce the formation of cytotoxic photoproducts of Hematoporphyrin Derivative. A better therapeutic response of a murine fibrosarcoma is found as compared to that of cw irradiation.

An intensified CCD video camera has been used to measure the spatial distribution of the fluorescence decay time in tumor-bearing mice sensitized with hematoporphyrin derivative. Mice were injected with five doses of sensitizer, ranging from 0.1 to 10 mg/kg body weight. For any drug dose the decay time of the exogenous fluorescence in the tumor is always significantly longer than in normal tissues. The image created by associating a gray-shade scale to the decay time matrix of each mouse permits a reliable and precise detection of the neoplasia.