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Biomedical subjects

M Panjehpour

Publications and source records attributed to M Panjehpour.

30 records · Page 2Linked to original sources
PubMed1993

Cytokine modulation of endothelial cell sensitivity to photodynamic therapy.

The purpose of this study was to determine if recombinant angiogenic cytokines modulate the sensitivity of endothelial cells to the toxic effects of chloroaluminum sulphonated phthalocyanine (AlSPc) photodynamic therapy (PDT). Bovine pulmonary artery endothelial cells in 24-well tissue culture plates were pretreated for 24 hr with AlSPc and either acidic fibroblast growth factor (FGF), platelet-derived growth factor (PDGF), tumor necrosis factor-alpha (TNF), interleukin-1-alpha (IL-1), or transforming growth factor-beta (TGF) followed by argon-pumped dye laser. Endothelial cell damage was monitored with 51chromium release. FGF, TGF, and, to a lesser extent, IL-1, enhanced the PDT-mediated damage to endothelial cells, whereas PDGF and TNF did not significantly modulate toxicity. The enhanced endothelial cell damage was seemingly not related to rate of cell proliferation or amount of photoactive drug uptake by the EC. These results suggest that presence of tumor secreted cytokines may enhance PDT-mediated toxicity of tumor associated endothelial cells.

Aluminum↗
PubMed1992

Centering balloon to improve esophageal photodynamic therapy.

A cylindrical balloon was developed to improve delivery of circumferential light for photodynamic therapy (PDT) of esophageal carcinoma. The balloon consisted of a 36-mm-long clear cylindrical membrane and a central tube to hold a cylindrical diffuser in the center of the lumen. Three isotropic probes were placed on the outside of the balloon to allow measurement of delivered light dose to the esophageal mucosa. The balloon was tested in the normal esophagus of 8 dogs that were injected with 4.0 mg/kg of PHOTOFRINR. Endoscopy was performed 48 hours following the injection, and under endoscopic observation the balloon assembly was passed, fixed in place, and inflated. A 1-cm cylindrical diffuser was passed into the central tube and 150, 300, and 600 Joules/cm of 630 nm laser light was delivered at 25 cm, 15 cm, and 5 cm proximal to the gastroesophageal junction. One control dog was illuminated using the cylindrical diffuser alone at doses of 300 and 600 Joules/cm of diffuser. Complete circumferential tissue response was obtained when the balloon was used. Relatively uniform light intensities were measured around the lumen. In contrast, noncircumferential and unpredictable PDT responses were generated when the cylindrical diffuser was used without the balloon.

Animals↗
PubMed1991

Nd:YAG laser-induced hyperthermia treatment of spontaneously occurring veterinary head and neck tumors.

Conventional hyperthermia treatment of superficial tumors in the oral cavity is troublesome due to difficulty in accessing the lesion. A new hyperthermia technique employing near-infrared radiation delivered through a flexible silica optical fiber is described. The system consisted of an Nd:YAG laser for tissue heating, a He-Ne laser for aiming beam, a computer-controlled optical shutter, an interstitial thermometer, computer, and a printer. A 3-m-long 600-microns silica fiber delivered laser energy to the tumor via surface illumination. Using the aiming beam, the spot size was adjusted to include 5 mm of surrounding normal tissue. A thermocouple implanted in the tumor base provided temperature feedback to maintain desired hyperthermic temperature within the lesion. Three spontaneously occurring canine (two squamous cell carcinomas on the gum, one pigmented melanoma on the hard palate) and one feline tumor (squamous cell carcinoma on the nose) have been treated with Nd:YAG laser hyperthermia. Hyperthermia was delivered at 43.5 degrees C for 1 h. All animals received standard radiation treatment prior to hyperthermia. Nd:YAG laser hyperthermia allowed effective and efficient delivery of heat to veterinary nasal and oral lesions otherwise not treatable with conventional heating techniques.

Aluminum Silicates↗
PubMed1991

Nd:YAG laser hyperthermia treatment of rat mammary adenocarcinoma in conjunction with surface cooling.

Electromagnetic radiation ranging from radiofrequency to microwave has classically been used to induce hyperthermia for treatment of cancer. This paper presents a new technique using near infrared radiation from an Nd:YAG laser in conjunction with surface cooling to induce hyperthermia in a rat tumor model. A CW Nd:YAG laser hyperthermia system was used to induce hyperthermic temperatures in chemically (DMBA) induced rat mammary adenocarcinomas. The laser was interfaced to a computer and a thermometry unit that provided feedback to control the tumor temperature between 43.2-43.5 degrees C. A thermocouple was placed at the base of the tumor and its temperature was used to control laser exposure. All tumors were 10 to 20 mm in diameter. Surface cooling methods investigated included forced air flow from a fan, forced oxygen flow plus an IV drip, and forced moist oxygen flow from a nebulizer. Twelve rat mammary adenocarcinomas have been treated with Nd:YAG laser hyperthermia. In 4 treatments, no surface cooling was employed. In one treatment the surface was cooled using oxygen flow plus IV drip. In 7 treatments the skin was cooled using the nebulizer technique. The nebulization provided the most effective and reproducible surface cooling. Nd:YAG laser hyperthermia delivered in conjunction with nebulizer surface cooling produced efficient heating of rat mammary adenocarcinomas. A mean temperature of 42.1 degrees C was obtained at the base of the tumors while the mean surface temperature was 37.0 degrees C.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1990

Nd:YAG laser-induced interstitial hyperthermia using a long frosted contact probe.

The heating potential of a closed loop interstitial hyperthermia system employing 1,064 nm laser light in conjunction with a long frosted contact probe was investigated in hind limb muscle of anesthetized dogs. The laser system was an Nd:YAG surgical laser modified with a single channel thermometry unit, a computer, a printer, and a computer-controlled laser exposure shutter. The long frosted laser probe was implanted into the muscle, and 3.12-5.00 Watts of laser power was delivered interstitially. Temperature distribution was measured in three dimensions around the frosted probe. The temperature distributions generated by this technique were satisfactory for producing desired hyperthermia temperatures in an approximately 3.5 cm3 cylindrical tissue volume. A multiple laser delivery system is needed to induce interstitial hyperthermia in large tumors. A significant potential for the long frosted contact probe may be its use in combining interstitial hyperthermia and interstitial photodynamic therapy. Using this technique, both modalities may be delivered while employing the same treatment setup.

Animals↗
PubMed1988

Blood flow values.

Explore the source record for details and available documents.

Blood Flow Velocity↗
PubMed1985

Canine normal and tumor tissue estimated blood flow during fractionated hyperthermia.

Time-temperature relationships are of critical importance in hyperthermia effects on tumors. Knowledge of temperature distributions within tumors is necessary to achieve maximal tumor response, and because blood flow is the major determinant of heat dissipation within tissue, knowledge of blood flow parameters is equally important. A mathematical model has been developed which estimates a parameter that may be related to regional tissue blood flow and is readily adaptable to clinical observations. Eight canine mast cell tumors were heated with interstitial radiofrequency (100 mHz) hyperthermia to a temperature range of 44 degrees C, +/- 0.5 degrees C, for 40 minutes. Estimated blood flow increased over the 40-minute treatment interval from 81 ml/min/100 gm of tissue at 10 minutes post-initiation of treatment to a maximum of 101.2 ml/min/100 gm of tissue at 30 minutes post-initiation of treatment. Over a 9-day period, during which both tumor and normal tissues were treated four times, values increased within the volume of interest. Maximum estimated blood flow within normal tissue increased from 115.7 ml/min/100 gm of tissue after 10 minutes of heating to a maximum of 121.7 ml/min/100 gm of tissue at 40 minutes. In contrast to normal tissue, eight canine mast cell sarcomas showed little change in estimated blood flow during 40 minutes of treatment. However, tumor tissue appears to undergo compensatory changes over the 9-day treatment interval with increases occurring in blood flow over that time period. These data underscore the importance of knowing blood flow characteristics within tumor and normal tissue.

Animals↗
PubMedDate not supplied

Photodynamic therapy in Barrett's esophagus: reduction of specialized mucosa, ablation of dysplasia, and treatment of superficial esophageal cancer.

Twelve patients with Barrett's esophagus and dysplasia were treated with photodynamic therapy. Five patients also had early, superficial esophageal cancers and five had esophageal polyps. Light was delivered via a standard diffuser or a centering esophageal balloon. Patients were maintained on omeprazole and followed for 6-54 months. In patients with Barrett's esophagus, photodynamic therapy ablated dysplastic mucosa and malignant mucosa in patients with superficial cancer. Healing and partial replacement of Barrett's mucosa with normal squamous epithelium occurred in all patients and complete replacement with squamous epithelium was found in three patients. Side effects included photosensitivity and mild-moderate chest pain and dysphagia for 5-7 days. In four patients with extensive circumferential mucosal ablation in the mid or proximal esophagus, healing was associated with esophageal strictures which were treated successfully by esophageal dilation. Strictures were not found in the distal esophagus. Photodynamic therapy combined with long-term acid inhibition provides effective endoscopic therapy of Barrett's mucosal dysplasia and superficial (Tis-T1) esophageal cancer. The windowed centering balloon improves delivery of photodynamic therapy to diffusely abnormal esophageal mucosa.

Adenocarcinoma↗
PubMedDate not supplied

A centering balloon for photodynamic therapy of esophageal cancer tested in a canine model.

Delivery of uniform circumferential light is desirable during photodynamic therapy of early or advanced esophageal cancer in human beings. Studies were performed in the canine esophagus to investigate whether use of a centering balloon would improve circumferential illumination of esophageal mucosa for photodynamic therapy of esophageal cancer. When the centering balloon was used, photodynamic therapy produced uniform and circumferential injury. With the cylindrical diffuser used in human studies, non-uniform and focal esophageal injury occurred. Placement of isotropic probes on the balloon wall allowed measurement and verification of relatively uniform light doses delivered to esophageal mucosa during balloon photodynamic therapy. The centering balloon has a potential role in improving light dosimetry during esophageal photodynamic therapy.

Animals↗
PubMedDate not supplied

The relationship of temperature profiles to frequency during interstitial hyperthermia.

Regional hyperthermia is currently being investigated as a potential adjuvant to radiation therapy treatment of malignant disease. Since tumor response is directly related to treatment temperature, thermal distributions within tumors and surrounding normal tissue must be predictable under various conditions. Normal canine muscle was heated to approximately 42 degrees C with radiofrequency current fields over the frequency range of 500 kHz to 300 MHz. With two rows of four interstitially implanted needles acting as electrodes, thermal profiles show that temperature increases occurred between the driving and ground plane electrodes. Temperature increases throughout the tissue were generally greatest at the center of the volume treated; however, the temperature profiles within the tissue were dependent upon selection of generator frequency. Temperature measurements with thermocouples placed within an RF field are difficult at frequencies over 500 kHz. At 500 kHz, induced RF current flow in microthermocouples is low enough to provide sensitive temperature measurement during periods of heating. This observation is significant because it allows treatment temperatures to be measured during the period of heating and subsequent control of heat deposition within the treated volume.

Animals↗