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Biomedical subjects

D R Doiron

Publications and source records attributed to D R Doiron.

At least 37 records · Page 2Linked to original sources
PubMed1984

Fluorescing cells in sputum after parenteral HpD.

Cells exfoliated into sputum were examined for fluorescence after the intravenous injection of HpD. Malignant and non-malignant cells were seen to fluoresce up to 9 days post injection of HpD. Not all exfoliated squamous cell cancer cells or non-malignant cells fluoresced. Implications are discussed relative to imaging diagnostic fluorescence bronchoscopy and photoradiation therapy of obstructing endobronchial cancers and bronchial carcinoma in situ.

Bronchial Neoplasms↗
PubMed1984

Phototoxicity of brain tissue in hematoporphyrin derivative treated mice.

Photoradiation therapy conditions which have been used to treat subcutaneous and breast tumors are lethal when applied to the head of mice. Treatment of control mice with laser light at 631 nm over an energy density range of 0-90j/cm2 had no measurable effect but mice photosensitized with 5 mg HPD/kg 72 hrs prior to laser treatment showed a threshold for brain damage at 56j/cm2, above which the mice developed cerebral edema and died. Laser treatment caused the same rate and magnitude of temperature rise in both control and HPD-photosensitized mice. Moreover, studies using mice whose brain temperature was kept below 37 degrees C during laser treatment showed a greater phototoxicity than mice without temperature regulation. Therefore, temperature rise in cerebral tissue was not associated with phototoxicity in the brain. In contrast the oxygen consumption rate in a brain cell suspension from an HPD-treated mouse was only 54% of that from a control mouse following treatment with laser light. This observation, when taken with supporting data from other investigations, suggests that one mechanism for the phototoxic response in brain tissue is oxygen deprivation resulting from mitochondrial damage.

Animals↗
PubMed1984

HpD photodynamic therapy for obstructing lung cancer.

Twenty-two patients with endobronchial cancer of the lungs have been treated with photoradiation therapy (PRT) employing a set protocol of 3.0 mg/kg hematoporphyrin derivative (HpD) administered intravenously 72 hours prior to red light (630 nm) illumination via a bronchoscope. Twenty patients showed a complete response. Of these, nineteen had large obstructing endobronchial tumors; one had a small mucosal lesion. Only one patient with an obstructing tumor showed a partial response. The one showing no response had an endobronchial mass that consisted of fibrous tissue, not tumor, as shown on three separate bronchoscopic biopsies.

Adult↗
PubMed1984

Imaging fluorescence bronchoscopy for localizing early bronchial cancer and carcinoma in situ.

A system of imaging fluorescence bronchoscopy instrumentation and methods has been devised that has succeeded in localizing very small (1 X 2 mm) areas of bronchial mucosal cancer, in individuals with radiologically occult lung cancer (positive sputum cytology for malignant cells and a negative chest X-ray). These areas were located solely by their fluorescence, and were visibly normal on white-light examination. The detection of lung cancer in individuals with radiologically occult lung cancer depends upon adequate methods of sputum collection and processing. Proving that fluorescing areas show "true positive" fluorescence depends upon accurate brush and forceps biopsies, providing adequate cytological and biopsy material. The entire system of the diagnosis and localization of early or pre-invasive lung cancer (while still confined to a bronchus) rests on skilled cytopathology methods and interpretation, not only skilled fluorescence bronchoscopic examination and adequate instrumentation.

Aged↗
PubMed1984

Photophysics of and instrumentation for porphyrin detection and activation.

In conclusion, when considering the photophysics of porphyrin detection and activation, it must be remembered that both processes are photon absorption initiated. As such, the absorption spectrum of the porphyrin, the wavelength or spectrum of the activating light, the rate of its delivery, its mode of delivery and the optical characteristics of the tissue must all be considered. When considering instrumentation, the spectral output or spectral sensitivity of the instrumentation must be considered. It is hoped that this review will provide basic knowledge to the new and established investigators in this area and thereby help to accelerate the field.

Biophysical Phenomena↗
PubMed1983

Hematoporphyrin derivative photoradiation therapy for the treatment of intraocular tumors: examination of acute normal ocular tissue toxicity.

Preclinical studies designed to define potential side effects resulting from the use of hematoporphyrin derivative (HPD) photoradiation therapy (PRT) as a modality for treating intraocular tumors have been performed. Pigmented rabbits were used to evaluate acute normal ocular tissue toxicity following single HPD PRT treatments in which the light was directed through the pupil and onto a 1-sq cm area of the retina. The treatment procedure consisted of the i.v. administration of HPD (1 to 10 mg/kg) followed 48 hr later by a 15-min exposure of localized red light [635 +/- 5 nm; 40 to 400 milliwatts/sq cm] generated by a free running rhodamine B dye laser pumped by a 5-watt argon laser. Toxicity to normal retinal tissue was documented using fundus photography, fluorescein angiography, and histological examination. The results of this study demonstrated that ocular damage in the form of retinal edema, detachment, and necrosis could be induced by clinically relevant doses of HPD PRT. The area of retinal damage was limited to the treatment field in all but the highest doses of HPD PRT. The histological results were in agreement with the visual observations in that abrupt and demarcated transition areas between injured and normal-appearing retina were observed. Care will have to be used in the delivery of light to the treatment field if HPD PRT is to be utilized for treatment of intraocular tumors.

Animals↗
PubMed1982

Fluorescence bronchoscopy in the localization of bronchogenic carcinoma.

Fluorescence bronchoscopy using hematoporphyrin derivative as a tumor marker has been developed for localization of early bronchogenic carcinoma. Recent clinical results have been obtained with a krypton laser and a fused quartz fiber illumination system, which is clearly superior to the mercury vapor lamp system used previously. Fifteen patients have been examined, two with the laser. The potential of the technique is demonstrated by a case study of a patient with positive sputum cytology and a negative chest radiograph. The small early invasive tumor could be detected only with difficulty by subtle mucosal changes under white light bronchoscopy. Positive fluorescence was observed in the suspicious area. Malignancy was confirmed by biopsy and histologic examination upon subsequent lobectomy.

Aged↗
PubMed1980

Tumor regression of human retinoblastoma in the nude mouse following photoradiation therapy: a preliminary report.

Retinoblastoma is the most common malignant intraocular neoplasm of childhood. Enucleation of both eyes is necessary in some advanced cases where radiotherpy and other modalities of treatment have failed. We present in this paper our initial observation that photoradiation therapy (the combination of the photosensitizing drug, hematoporphyrin derivative, and red light) produces marked tumor cytotoxicity in human retinoblastoma heterotransplanted into the anterior chamber of the nude mouse eye.

Animals↗
PubMed1979

Fluorescence bronchoscopy for detection of lung cancer.

A system using the fluorescence bronchoscope has been designed for localization of small, early bronchogenic carcinoma by the fluorescence of previously injected hematoporphyrin derivative. The system included a 200W mercury vapor lamp and primary filter, flexible fiberoptic bronchoscope with special violet-transmitting light conductor, secondary filter, and image intensifier tube. Tests indicated the system could detect a tumor only 100 micron thick at the expected concentration of hematoporphyrin derivative: 1 microgram/gm at 48 to 96 hours following intravenous injection at a dosage of 2.5 mg/kg. Examination of resected specimens (six of lung, one of esophagus) showed positive fluorescence in all cases, with fluorescence visible beyond the region visible under conventional white light examination. Fluorescence bronchoscopy has been performed on four patients thus far. Positive fluorescence was observed in all three cases where the tumor had been known to occur. Positive fluorescence was also observed in the patient with sputum positive for lung cancer, but negative x-ray film findings. However, additional examinations are required to demonstrate the smallest lesion that can be detected in vivo.

Bronchoscopes↗
PubMed1977

A feasibility study of the use of fluorescence bronchoscopy for localization of small lung tumours.

The possible use of fluorescence bronchoscopy for localization of bronchogenic tumours at the carcinoma in situ stage has been investigated. The target lesion is 80 micrometer thick with a mass of 250 microgram, containing 250 pg of haematoporphyrin derivative. The injected haematoporphyrin-derivative is preferentially taken up or retained by a malignant tumour, and can be detected in small amounts by its red flourescence under illumination by violet light. Previous clincial trials were successful in detecting tumours, but the instrumentation was only marginally adequate, the fluorescent compound was not standardized and no measurements or calculation of sensitivity were made. In this work, a fibreoptic bronchoscope system with a 200 W mercury vapour lamp, special violet-transmitting light conductor, sharp cut-off blue and red filters and three-stage image intensifier tube was designed and assembled. Measurements in vitro indicate the design objectives were met, and test on tumours are in progress.

Animals↗
PubMedDate not supplied

Laser fluorescence bronchoscope for localization of occult lung tumors.

A system for imaging occult bronchogenic carcinoma by the fluorescence of previously-injected, tumor-specific compound hematoporphyrin-derivative has been assembled and successfully used to locate a tumor 1 mm thick. The violet excitation source is a krypton ion laser coupled to fused quartz fiber light conductor. An electrostatic image intensifier attached to a standard flexible fiberoptic bronchoscope provides a bright image even at relatively low irradiance. A red secondary filter rejects most reflected background and autofluorescence. Sensitivity and contrast capability of the system should permit detection of a tumor less than 0.1 mm thick.

Bronchoscopes↗