Laser-induced fluorescence studies of the biodistribution of carotenoporphyrins in mice

Strategies for high-resolution imaging of epithelial ovarian cancer by laparoscopic nonlinear microscopy

Ovarian cancer remains the most frequently lethal of the gynecologic cancers owing to the late detection of this disease. Here, by using human specimens and three mouse models of ovarian cancer, we tested the feasibility of nonlinear imaging approaches, the multiphoton microscopy (MPM) and second harmonic generation (SHG) to serve as complementary tools for ovarian cancer diagnosis. We demonstrate that MPM/SHG of intrinsic tissue emissions allows visualization of unfixed, unsectioned, and unstained tissues at a resolution comparable to that of routinely processed histologic sections. In addition to permitting discrimination between normal and neoplastic tissues according to pathological criteria, the method facilitates morphometric assessment of specimens and detection of very early cellular changes in the ovarian surface epithelium. A red shift in cellular intrinsic fluorescence and collagen structural alterations have been identified as additional cancer-associated changes that are indiscernible by conventional pathologic techniques. Importantly, the feasibility of in vivo laparoscopic MPM/SHG is demonstrated by using a "stick" objective lens. Intravital detection of neoplastic lesions has been further facilitated by low-magnification identification of an indicator for cathepsin activity followed by MPM laparoscopic imaging. Taken together, these results demonstrate that MPM may be translatable to clinical settings as an endoscopic approach suitable for high-resolution optical biopsies as well as a pathology tool for rapid initial assessment of ovarian cancer samples.

Oxidative cleavage of plasmid bluescript by water-soluble Mn-porphyrins and artificial oxidants or molecular oxygen

A set of eight Mn(III)-porphyrins were used as catalysts in oxidative demolition of Plasmid Bluescript, to the nicked and linear forms, in the presence of different oxygen donors (NaOCl, H(2)O(2), AcOOH, t-BuOOH). The efficiency of the catalytic system is related to a combination of factors such as porphyrin structures, pH of the aqueous phase and nature of the primary oxidant. The highest catalytic activity was observed when ionic porphyrins were used as catalyst (the cationic being more active than the anionic) and NaOCl was used as primary oxidant at pH 9.5; in contrast, lipophilic catalysts proved to be completely unreactive towards the DNA, whichever oxidant used. The plasmid demolition was also achieved by irradiating the reaction mixture, containing Zinc porphyrins, with a white lamp; under these conditions, the highest efficiency was again observed with meso-tetra(1-methyl-4-pyridyl)porphyrin. However, preliminary experiments of photo activation applied on tumour cells (HCT 116) showed no dead cells with cationic porphyrin, while the amphiphilic Zn-tetra(4-hydroxyphenyl)porphyrin gave IC(50) values at 5 x 10(-2) microM concentration (37.1 ng/mL).

MS-2 fibrosarcoma characterization by laser induced autofluorescence

BACKGROUND AND OBJECTIVE

MS-2 fibrosarcoma implanted in BALB-CDF1 mice was investigated by frequency and time domain measurements of the autofluorescence (AF) radiation emitted upon excitation by a N(2) laser beam (337.1 nm).

STUDY DESIGN/MATERIALS AND METHODS

AF spectra were obtained by using a spectrograph, a multichannel plate and an optical multichannel analyzer for the steady state detection. Time-resolved spectra were performed by means of a monochromator, a photomultiplier, and a digital signal analyzer.

RESULTS

Spectral measurements show that the autofluorescence intensity of pathologic tissue is lower than that of healthy one in the 400- to 500- spectral region. In the same spectral range, we found the fluorescence decay to be the sum of a fast and a slow component. The lifetime of the fast component of tumoral tissue is significantly lower than that of healthy samples.

CONCLUSION

Frequency and time domain measurements used in combination show that MS2-fibrosarcoma is characterized by the probable presence of the free form of NADH.

Localisation and accumulation of a new carotenoporphyrin in two primary tumour models

We have investigated the tumour-localising properties and in vivo fluorescence kinetics of a hexamethoxylated carotenqporphyrin (CP6) in two primary tumour models: UV-B-induced early skin cancer in hairless mice and chemically induced mucosal dysplasia in the rat palate. CP6 fluorescence kinetics are investigated by measuring in vivo fluorescence spectra and images of the mouse skin and the rat palate at different time points after injection. For the tumour-localising properties, microscopic phase-contrast and fluorescence images are recorded. The in vivo fluorescence kinetics in the mouse skin show localization of CP6 in the tumours. However, fluorescence microscopy images show that CP6 localises in the dermis and structures that are not related to the malignant transformation of the mouse skin. The fluorescence kinetics in the rat palate show a significant correlation between the degree of malignancy and the CP6 fluorescence build-up time in the palate. The microscopic images show that CP6 fluorescence localises in the connective tissue and not in the dysplastic epithelium. In conclusion, CP6 does not localise preferentially in (pre-) cancerous tissue in the two primary tumour models studied here, in contrast to reports about localisation of carotenoporphyrins in transplanted tumours. However, the CP6 build-up time in rat palates correlates with the degree of malignancy and this might possibly be a useful parameter in tumour detection.