Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0035412 (rhabdomyosarcoma)
 6,156 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Interstitial photodynamic therapy (IPDT) using Photofrin II (PII) as photosensitizer has been studied in the rat rhabdomyosarcoma R-1, growing on the thigh or flank of WAG-Rij rats. A light dose-response relationship has been established, for 10 mg PII/kg i.v. and irradiation 24 hr later, with local tumor control as the end point for single IPDT treatments using four cylindrical diffusors simultaneously. A light energy fluence of 150-200 Joule/cm2 (wavelength 625 nm), measured in vivo at the tumor periphery, was required for tumor control. Comparison of tumor response at 5 and 2.5 mg PII/kg with the complete dose response relationship at 10 mg PII/kg suggests drug-light dose reciprocity and indicates that in our tumor model treatment failures are not likely to be caused by variations in (tumor) tissue photosensitizer level, but rather by insufficient light dose or inadequate light dose distribution. Increasing the interval between PII administration and irradiation from 24 hr to 48 hr had no great effect on tumor response to IPDT in this study. Inspection of the original tumor site 100 days after tumor control revealed obvious loss of thigh muscle tissue. Also, recurrent tumors showed a reduced growth rate. Therefore, the relationship between tumor (re)growth and PDT-induced normal tissue damage was studied and the existence of a tumor bed effect was confirmed. The present study indicates that tumor control after a single IPDT treatment is feasible, but that PDT induced damage to a margin of the adjacent normal tissue is probably required.
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PMID:Tumor and normal tissue response to interstitial photodynamic therapy of the rat R-1 rhabdomyosarcoma. 153 69

Photodynamic therapy (PDT) involves the activation of photosensitizing drugs by light of appropriate wavelength. The photosensitive agent Hematoporphyrin Derivative (HPD) appears to be preferentially retained in malignant tumors; irradiation of HPD-containing tissue by light of appropriate wavelength (625 nm) and dose leads to (tumor) tissue destruction. The aim of this study is to achieve maximum tumor control probability with minimum normal tissue photosensitivity. In previous work from our laboratory it has been demonstrated that PDT has its fundamental effects on the tumor and normal tissue microcirculation. As it is well established that hyperthermia (HT) has its major effects in less well vascularized areas of the tumor, the combined modality of HT and PDT might prove to be advantageous. Moreover, suppression of sublethal damage repair by HT has been observed. To overcome the problem of poor light penetration into tissues and the high rate of recurrences following PDT with external irradiation, the combined effects of interstitial PDT with interstitial hyperthermia in a new line of animal experiments were studied in our laboratory. An experimental murine tumor (Rhabdomyosarcoma, type R-1) was transplanted in WAG/Rij rats and, after reaching an average diameter of 2 cm, the active component of HPD, that is Photofrin II, was injected intravenously in different dose schedules (5 mg/kg, 10 mg/kg). After 24 or 48 hrs the tumors were implanted with four flexible catheters, through which either light or heat could be applied. Light was obtained from an Argon-Dye laser system tuned to a wavelength of 625 nm at a dose rate of 75-100 mW per fiber to a dose level of 900 Joule from four linear light applicators. Heat (44 degrees C/30') was delivered by four 27 MHz radiofrequency antennas. Dose response relationships for PDT alone, HT alone and PDT combined with HT were established with cure as endpoint. This study showed that these two modalities, in the proper sequence and spacing, result in an augmented cytotoxicity on the tumor cells in vivo. With the combined modality treatment a cure rate of 41% (90 days) was obtained. As the implantation of flexible catheters is a well-known technique in radiation therapy practice, the potentiating effects of interstitial HT combined with interstitial PDT in solid tumors is very promising and clinical studies are warranted.
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PMID:Interaction of interstitial photodynamic therapy and interstitial hyperthermia in a rat rhabdomyosarcoma--a pilot study. 296 16

This paper deals with the interaction of interstitial hyperthermia (HT) and interstitial photodynamic therapy (PDT). Its main focus, however, is on a newly developed heating system; phantom studies as well as temperature-response data obtained from the in vivo experiments are presented. Heat was delivered by thin, flexible wire antennas operating at a frequency of 27 MHz. Measurements in muscle-equivalent phantom with infrared thermography were performed. Uniform heating over the inserted length of the antenna was obtained and impedance matching appears possible by simple variable air coils, thereby minimizing the reflected power to less than 20%. Light was obtained from an Argon-Dye laser system tuned to a wavelength of 625 nm at a dose rate of 75-100 mW per fiber to a total incident dose of 900 J from four linear light applicators. An experimental murine tumor (Rhabdomyosarcoma, type R-1) was transplanted in WAG/Rij rats and, after reaching an average diameter of 2 cm, the active component of haematoporphyrin derivative (HPD), Photofrin II, was injected intravenously. The tumors were subsequently implanted with four flexible catheters, through which either light or heat could be applied. Dose-response relationships for PDT alone, HT alone and PDT followed by HT were established with cure as endpoint. The animal experiments showed that with the use of low-frequency wires a good localized heat distribution in the tumors can be obtained. Moreover, this study showed that PDT and HT, in the proper sequence and only when optimal temperatures are reached, result in an augmented cytotoxicity on the tumor cells in vivo; i.e. a cure rate of 41% was obtained.
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PMID:Interstitial hyperthermia using 27 MHz wire antennas and interstitial photodynamic therapy in a rat rhabdomyosarcoma: phantom and animal studies. 335 20