Photodynamic Therapy (PDT) is an emerging and promising therapeutic modality for treatment of a wide variety of malignant and nononcologic tumors, as well as in the treatment of infected skin ulcers. This study evaluated the effectiveness of the PDT to treat a chronic skin wound that had been already subjected to several clinical and surgical type treatments in a dog. The animal with an infected chronic skin wound with 8 cm diameter in the left leg received an injection of an aqueous solution of 1% methylene blue (MB) with 2% lidocaine into the lesion. After MB injection the wound was irradiated using a LED (LED-VET MMOptics(r)) with a wavelength between 600 and 700 nm, 2 cm diameter circular light beam, of 150 mW of power, light dose of 50 J/cm2. After 3 and 6 weeks PDT was repeated and the wound was re-evaluated. Complete healing was achieved 10 weeks after the first procedure.
Biomedical applications of near-infrared Raman spectroscopy have increased their importance at the last ten
years. This technique can determinate the molecular composition of materials, allowing a sensible and fast
biological diagnosis. It has showed to be a promising tool for health diagnosis due to its high sensibility.
Colorectal cancer (CRC) is one of the most common malignant tumors in humans beings. In the last decades
many experimental models have been developed in animals based in the use of chemical composites to
induce the formation and development of these tumors, many of them present similar characteristics to those
of natural occurrence aiming to the attainment of information on genesis, evolution, as well as diagnosis and
more efficient therapies for treating these neoplasias. Amongst the most used chemical composites is the 1,2-
dimetilhydrazine (DMH) because its morphological and histological similarity to those tumors. This study aims
to compare in vivo normal colon tissue and tumoral colon tissue, induced by DMH, in rats by near-infrared
Raman spectroscopy to permit the use in the near future for an efficient diagnosis in real time besides being
useful as an auxiliary method for several therapies, including the photodynamic therapy.
A six-year old Holstein cow with an eye cancer (ocular squamous cell carcinoma) involving the third eyelid and
conjunctiva was submitted to photodynamic therapy using intratumoral 20% aminolevulinic acid (5-ALA - Aldrich
Chemical Company, Milwaukee, USA) and a light emitting diode (LED - VET LED - MMOptics(R)) with wavelength
between 600 and 700 nm, 2 cm diameter circular light beam, power of 150 mW, light dose of 50 J/cm2 as a source of
irradiation. Fifteen days after the experimental procedure we observed about 50% tumor reduction and complete
remission after 3 months. Relapse was not observed up to 12 months after the treatment. Although the study only
includes one animal not allowing definite conclusions, it indicates that PDT represents a safe and technically feasible
approach in the treatment of eye cancer in cattle.
Photodynamic therapy (PDT) has been widely studied in the last decades and it is becoming a promising tool in the treatment of tumors of many kinds. PDT is based on photoactivation of a sensitized drug that is restrained in the tumor cells, producing highly reactive species that can destroy tumoral cells with minimum collateral effect. This study aimed to evaluate the effect of the PDT in induced neoplasias of the colon by 1,2-dimetilhidrazine in rats, using as photosensitizing drug the chloroaluminum phthalocyanine incorporated to the liposomes and to compare the methods of irradiation using continuous or fractionated energy in PDT. Ten Wistar rats were distributed randomly in 3 groups (G1, G2 and C), anaesthetized and submitted to PDT with of fractionated (G1) or continuum (G2) irradiation energy using as a source of excitement an InGaAl laser. After 3 hours of the laser irradiation, 2 animals of the G1 group, 2 animals of the G2 group and 1 animal of C group were sacrificed and samples of tumoral tissue were collected for histological analysis; the same procedure was carried through 24 hours after irradiation. There were no significant differences between the extensions of the induced areas of necrosis for PDT in the groups under fractionated or continuous irradiation for the parameters used in this study. New studies must be carried through, using different parameters and intervals of laser irradiation, aiming to maximize the effect of the PDT for the treatment of colon tumors.
The Transmissible Venereal Tumor (TVT) is a very common neoplasic disease in a free-roaming dogs which affects the extern genital and presenting resistance to conventional drugs that promote high toxicity. Photodynamic Therapy (PDT) is based in tumor cells irradiation after absorption of photosensitizer substance. At present, the protoporphirin IX (PP IX) has been explored in PDT due to be endogen, then it does not present toxicity effect. This substance can be obtained by exogenous way through aminolevulinic acid (5-ALA) administration in patient. The aim of this work was establish the optimal conditions for PDD (Phodynamic Diagnosis) to irradiate the tumor after ALA administration through fluorescence spectroscopy to improve the results with PDT. In this research was studied the 5-ALA 20% absorption in TVT of vaginal and penial mucous of a female and a male dog, respectivaly. This drug was administrated topically and after 30 minutes the fluorescence spectra were collected in intervals of 15 minutes during 120 minutes. The results showed that the maximum peak of PP IX in the tumor was between 60 and 105 minutes after the ALA application. In conclusion, the optimum effect will be achieved irradiating the tumor tissue into this period.
Comparative studies were carried out on the Al- phthalocyanine and Zn-phthalocyanine uptake in iliac artery wall of rabbit, through transadventitial fluorescence measurements. Two 3.5 Kg Norfolk make rabbit were used. The iliac artery was dissected, isolated and clamped at two points, 1.5 cm apart. The experiment comprised three steps, collecting fluorescence spectra at several point inside and outside of the clamped region of the artery. The excitation source was a 488 nm Argon Laser. Firstly, it was measured the pre and post clamping transadventitial fluorescence without the photosensitizer. After that, 50 (mu) L of AlPc or ZnPc solutions in Cremiphor EL, 2.5 (mu) M, were injected locally into the artery clamped region of each rabbit and fluorescence spectra were collected at t equals 0 and 15 min. Finally, elapsed 30 min. Temporal evolution of the drug uptake by the artery wall was studied analyzing the intensities of the fluorescence peaks at 682 and 678 nm for AlPc and ZnPc, respectively. It was found that AlPc is more absorbed and remains for a longer time in the iliac artery wall than the ZnPc.
A growing number of studies have demonstrated that autofluorescence and induced fluorescence spectroscopy can be used to distinguish normal and abnormal tissues in vivo. Through photochemical accumulation in atherosclerotic lesions it is possible to obtain induced fluorescence, this accumulation has been demonstrated in many researches. The aim of this study was to diagnose, by aluminum phthalocyanine transadventitial fluorescence, atherosclerotic plaques in artery wall of rabbits. Five male Norfolk rabbits were submitted to a high level cholesterol diet for 9 weeks. When the blood cholesterol level reached around 1000 mg/dl three of these animals were injected intravenously 50(M/50(l of aluminum phthalocyanine (AlPc). After 24 hours these animals were submitted to a surgery to expose the iliac artery. The transadventitial fluorescence spectra were acquired in several points over the artery. Characteristic peaks of the collagen, the porphyrin and the induced by AlPc were observed.
The aim of this work was to verify the Al-Phthalocyanine (AlPc) absorption in iliac artery wall of a rabbit, through transadventitial fluorescence measurement. Two Norfolk male rabbits, weighing 3.5 kg were used. The iliac artery was dissected and isolated. The artery was then clamped in two points with simple ligatures spaced 1.5 cm. The experiment was made in three phases, with acquisition of several fluorescence spectra in different points of the iliac artery. Firstly was measured the pre and post clamping transadventitial fluorescence without the presence of the photosensitizer. On the second phase, the AlPc, 2.5 (mu) M in 50 (mu) L solution, was injected locally into the clamped region and fluorescence spectra were collected in t=0 minutes and t=15 minutes. Finally, 30 minutes from the beginning of the experiment the clamping was removed, the blood flow restarted into the artery, and the fluorescence spectra was collected in t=5 minutes and t=10 minutes. The excitation was made using an Argon Laser (Stabilite 2017-Spectra Physics), operating in 488nm with 7mW optical power measured at the distal fiber tip. A unique peak, centered in 682nm, identifies the AlPc presence on the analyzed tissue.
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