No abstract

The design and characterization of optical phantoms which have the same absorption and scattering characteristics as biological tissues in a broad spectral window (between 400 and 650 nm) are presented. These low-cost phantoms use agarose dissolved in water as the transparent matrix. The latter is loaded with various amounts of silicon dioxide, Intralipid, ink, blood, azide, penicillin, bovine serum, and fluorochromes. The silicon dioxide and Intralipid particles are responsible for the light scattering whereas the ink and blood are the absorbers. The penicillin and the azide are used to ensure the conservation of such phantoms when stored at 4 degrees C. The serum and fluorochromes, such as Coumarin 30, produce an autofluorescence similar to human tissues. Various fluorochromes or photosensitizers can be added to these phantoms to simulate a cancer photodetection procedure. The absorption and fluorescence spectroscopy of the porphyrin-type fluorescent markers used clinically for such photodetection procedures is similar in these phantoms and in live tissues. The mechanical properties of these gelatinous phantoms are also of interest as they can easily be moulded and reshaped with a conventional cutter, so that complex structures and shapes, with different optical properties, can be designed. The optical properties of these phantoms were determined between 400 and 650 nm by measuring their effective attenuation coefficient (mu eff) and total reflectance (Rd). The microscopic absorption and reduced scattering coefficients (mu a, mu s') were deduced from mu eff and Rd using a Monte Carlo simulation.

To evaluate and parametrize transport models for the vadose (partially water-unsaturated) zone, information about the spatial distributions of solutes is needed. We describe a technique for the simultaneous imaging of several fluorescent tracers in structured field soils. With this technique, we obtain information on local mixing under field conditions. Local dispersion is a decisive process that discriminates different flow regimes. The imaging device consists of a high-power xenon lamp and a sensitive charge coupled device (CCD) camera. The three fluorescent dyes Brilliant sulfaflavine (BF), Sulforhodamine B (SB), and Oxazine 170 (OX) were chosen as solute tracers for their spectroscopic properties and different sorption coefficients. We conducted a field experiment using these tracers and took images of their distribution in a vertical soil profile. The fluorescence images (1242 by 1152 pixels) were corrected for nonuniform lighting, changing surface roughness, and varying optical properties of the soil profile. The resulting two-dimensional relative concentration distributions were similar for BF and SB. The reason might be the fast transport regime, which prevents the establishment of sorption equilibria. According to its higher sorption coefficient, OX was more strongly retarded. In this paper, we show that the fluorescence imaging technique is a powerful tool for the in-situ investigation of transport processes of fluorescent solute tracers in soil profiles. Due to the high spatial resolution of the tracer concentration maps and the ability to detect the flow field characteristics of differently reactive tracers simultaneously under field conditions, this technique provides valuable experimental data for the test and development of theoretical models for heterogeneous solute transport in soils.

Based on previous experiments in nude mice, showing that fluoresceinated monoclonal antibodies against carinoembryonic antigen localized specifically in human carcinoma xenografts and could be detected by laser-induced fluorescence, we performed a feaibilit study to determine whether this immunopho method could be applied in the clinic. Six patients, with known primary colorectal carcinoma, received an i.v. injection of 4.5 or 9 mg of mousehuman chimeric anti-carcinoembryonic antigen monoclonal antibody coupled with 0.10-0.28 mg offluorescein (molar ratio 1/10 to 1/14). The monoclonal antibody was also labeled with 0.2-0.4 mCi of 12-I (1 Ci = 37 GBq). Photodetection of the tumor was done ex vivo on surgically resected tissues for the six patients and in vivo by fluorescence rectosigmoidoscopy for the sixth patient. Upon laser irradiation, ciearly detectable heterogeneous green fluorescence from the dye-antibody conjugate was visually observed on all six tumors; almost no such fluorescence was detectable on normal mucosa. The yellowish tissue autofluorescence, which was emitted from both tumor and normal mucosa, could be subtracted by real-time image processing. Radioactivity measurements confirmed the specificity of tumor localization by the conjugate; tissue concentrations of up to 0.059% Injected dose per g of tumor and 10 times les (0.006%) per g of normal mucosa were found. The overall results demonstrate the feasibility of tumor immunophotodiagnosis at the clinical level.chlorins, have been coupled to monoclonal antibodies (mAbs), but these conjugates were studied primarily in vitro (6)(7)(8), and the few experimental immunophototherapy studies did not yield highly significant results (9). The obvious advantage of using mAbs as vectors for tumor localization of dyes is the ability of a mAb to bind specifically to an antigen that is more abundant in tumor than in normal tissue. Furthermore, this technique allows selection of the dye on the basis of its photophysical and spectral properties, independently of its weak tumor-localizing properties.We chose human-mouse chimeric mAb directed against carcinoembryonic antigen (CEA) (10) because anti-CEA antibodies have given the best experimental and clinical results for colorectal carcinoma localization (11, 12) and chimeric mAbs were less immunogenic in patients than their murine counterpart (13). We selected fluorescein as the dye, primarily for its favorable photophysical properties, as shown in the innumerable in vitro applications of mAb-fluorescein conjugates and secondly because it can be injected in large doses into patients without side effects (14).We have previously shown that anti-CEA mAb-fluorescein conjugates injected i.v. in nude mice bearing human colon carcinoma xenografts allow clear immunophotodetection of these tumors (15). The purpose of the present pilot clinical trial was to determine whether such type of tumor immunophotodiagnosis is feasible in patients.Despite major progress in understanding the process of malignant transformation ...