John Tulip | Xplore Research, University of Alberta (original) (raw)

Papers by John Tulip

Applied Physics Letters, 1975

A high-pressure glow discharge in flowing gases is described. The cathode surface and the dischar... more A high-pressure glow discharge in flowing gases is described. The cathode surface and the discharge glow are isolated by a mica sheet with a matrix of holes drilled into it. The cathode is differentially pumped to a pressure of approximately 1 Torr. This electrode structure has produced a discharge power density of 15 W/cm3 when the gas residence time is 3 ms.

A summary of the development of a database for a geographic information system. The commonly desc... more A summary of the development of a database for a geographic information system. The commonly described disadvantages of the relational model (fixed length fields and an excess of tables) were overcome in a variety of ways, allowing the retention of the advantages of the model. The Binary Data Model (BDM) was used to define the system specifications. A software tool was developed to convert the BDM specification into tables in a relational model and into an object oriented interface to the relational database. A small, dedicated development team followed a strict development cycle, resulting in all major milestones being met. One of the main themes in this paper is the handling of complex (spatial) data that does not obviously suit the relational model.

Journal of Applied Physics, 1980

Backscattering cross sections for depolarization are derived for the active remote sensing of a t... more Backscattering cross sections for depolarization are derived for the active remote sensing of a two-layer random medium. It is shown that the depolarization effects arise as a second-order term in albedo under the Born approximation. The results of the backscattering cross sections are illustrated as functions of frequency and incident angles and used to match experimental data collected from a vegetation field.

Lasers, Sources, and Related Photonic Devices, 2012

Abstract We demonstrate our progress in developing an application of mid-IR External Cavity Quant... more Abstract We demonstrate our progress in developing an application of mid-IR External Cavity Quantum Cascade Laser (EC-QCL) for concentration measurements of benzene, toluene, ethylbenzene and o-and p-xylene (BTEX) in a simulation chamber.

Lasers in Surgery and Medicine, 1996

Although laser angioplasty has been demonstrated to be effective for the treatment of long, compl... more Although laser angioplasty has been demonstrated to be effective for the treatment of long, complex coronary arterial atherosclerotic stenoses, there is an associated risk of acute arterial spasm, dissection, and perforation as well as a significant restenosis rate. It has been postulated that the use of lasers emitting at wavelengths designed for radiation absorption by water would decrease local tissue trauma. We have examined the use of a Nd:YAG laser designed to emit at 1.44 microns, an absorption peak for water, and compared the results of laser ablation at 1.06 microns, 1.32 microns, and 1.44 microns wavelengths. Nd:YAG laser angioplasty was performed in the abdominal aorta of White Leghorn roosters. Acute and chronic vascular trauma was assessed by contrast angiography and histological analysis. There was a significant decrease in early mortality with 1.44 microns laser ablation. This decreased mortality after 1.44 microns ablation was associated with a decrease in vascular spasm, perforation, and thermal damage. Atherosclerotic plaque development at follow up was decreased with 1.44 microns ablation but this was not significant. 1.44 microns laser ablation decreases early vascular trauma and mortality and may decrease subsequent atherosclerotic plaque development.

Lasers in Surgery and Medicine, 1999

Transplant vasculopathy is a leading cause of late cardiac graft loss. We have examined laser-ind... more Transplant vasculopathy is a leading cause of late cardiac graft loss. We have examined laser-induced fluorescence (LIF) spectroscopy as an optical diagnostic tool for detection of intimal plaque development and inflammatory cellular invasion in a rat model of aortic allograft transplant. Infrarenal aortic segments were transplanted from Lewis to Sprague Dawley rats. A range of vasculopathy development was produced by treatment with a viral anti-inflammatory protein. LIF spectra were recorded from the intima of aortic implants at 28 days. Fluorescence intensity was analyzed for correlation with vasculopathy development. Significant differences in LIF intensity at 400-450 nm (P &amp;amp;amp;lt; or = 0.05 by ANOVA) were detected. LIF emission was correlated with plaque growth (R2 = 0.980), vessel narrowing (R2 = 0.964), and cellular invasion (R2 = 0.971) by regression analysis. LIF optical analysis provides a nontraumatic diagnostic approach for detection of atherosclerosis prior to cardiac transplant or during development of vasculopathy after transplant.

Lasers in Surgery and Medicine, 1991

Laser-induced fluorescence has been developed as a guidance system for laser angioplasty. Laser a... more Laser-induced fluorescence has been developed as a guidance system for laser angioplasty. Laser ablation has been used for resection of arrhythmogenic ventricular scar. We have investigated the use of laser-induced fluorescence for the detection of fibrotic and ischemic changes in endocardium and myocardium. Fluorescence emission spectra from human necropsy specimens were correlated with histologic examination. Normalized fluorescence intensity detected from both the endocardia1 and the myocardial surfaces of the fibrotic ventricular specimens was significantly higher than that of corresponding normal specimens at 440 to 475 nm. Fibrotic endocardium could be identified by a fluorescence emission intensity ratio less than 1.5 for wavelength ratio 375/450nm. Acutely infarcted endocardium was recognizable by a ratio of 1.5 to 2.0. The specificity and sensitivity of detection of scarred endocardium was 70 and loo%, respectively.

The Journal of Urology, 2003

Purpose: Photodynamic therapy after intravenous injection of Photofrin (QLT Phototherapeutics, Va... more Purpose: Photodynamic therapy after intravenous injection of Photofrin (QLT Phototherapeutics, Vancouver, British Columbia, Canada) results in a contracted bladder and skin photosensitivity, which limits its clinical application. In an attempt to overcome these limitations photodynamic therapy after intravesical instillation of Photofrin or 5-aminolevulinic acid (ALA) in an orthotopic rat bladder tumor model was explored and compared with intravenous Photofrin for photodynamic therapy efficacy and phototoxicity.

The Journal of Urology, 2007

We determined the feasibility of complete treatment of the canine prostate and long-term effectiv... more We determined the feasibility of complete treatment of the canine prostate and long-term effectiveness of interstitial photodynamic therapy using the intra-arterial photosensitizer QLT0074 (benzoporphyrin derivative 1,3-diene C,D-diethylene glycol ester A ring) (QLT, Vancouver, British Columbia, Canada) administration and pulsed light delivery. Materials and Methods: The prostate gland of 11 dogs were infused with QLT0074 via the prostatovesical arteries (2 mg drug per artery bilaterally) under fluoroscopic guidance. Immediately following infusion the prostate was surgically exposed and 7 optical fibers with 1.5 cm cylindrical diffusers in after loading sheaths were inserted into the prostate through a template. Light was delivered sequentially to the optic fibers via a computer driven switch system. One dog was sacrificed 6 days after photodynamic therapy to assess acute tissue effects. The other 10 dogs were monitored for clinical tolerance and urinary function, and sacrificed at between 3 and 11 months. Prostate specimens were examined microscopically to evaluate long-term tissue reactions. Results: Comprehensive destruction of the prostate was noted in the acute dog. Except for urinary retention and mild hematuria no other perioperative complications were observed in the chronic dogs. Urodynamic examination did not reveal deleterious bladder and urethral function. Average prostate volume decreased 71% at 3 months and 56% after 6 months (p ϭ 0.007 and 0.014, respectively). Microscopic evaluation revealed prostate glandular epithelial atrophy, stromal fibrosis and mononuclear cell infiltration. Conclusions: Interstitial photodynamic therapy using intra-arterial QLT0074 and pulsed light delivery is safe and feasible for comprehensive destruction of the canine prostate. Clinical trials are required to confirm it for managing prostate diseases.

Journal of Neurosurgery, 1989

A wavelength-shifted Nd:YAG laser, tuned to coincide with the infrared absorption peak of water a... more A wavelength-shifted Nd:YAG laser, tuned to coincide with the infrared absorption peak of water at 1.44 microns, was used to make lesions in normal rabbit brain. A total of 48 lesions were made with power up to 20 W, with energy up to 40 joules, and with two different spot sizes. These lesions were compared to lesions made with 1.06

Journal of Neuro-Oncology, 1985

Brain and glioma tissue levels of tritiated hematoporphyrin derivative (3H-HPD) were measured in ... more Brain and glioma tissue levels of tritiated hematoporphyrin derivative (3H-HPD) were measured in normal and 9L intracerebral glioma-bearing rats at 24 hours following administration of 3H-HPD 2-20 mg/kg and at 24-120 hours after 3H-HPD 10 mg/kg. Levels of 3H-HPD in blood, liver, spleen and muscle were also measured. Tissue levels of 3H-HPD increased progressively as the dose was increased. In animals given 10 mg/kg, gradual decreases in tissue levels occurred between 24 and 72 hours but thereafter remained stable. The 3H-HPD level in gliomas was consistently 2-3 X greater than in brain tissue, despite changes in dosage and time interval. High levels of activity were measured in normal brain tissue at all dosage levels, and subsequent clearance of the 3H-HPD from brain, glioma, and other tissues was slow; at 120 hours after administration of 10 mg/kg, approximately 50% of the 24 hour level was still present. These results indicate that although a dose- and time-independent preferential uptake of hematoporphyrin derivative occurs in intracerebral gliomas, persistent high levels may be present in the surrounding brain. The disadvantages of using hematoporphyrin derivative rather than its individual components in studies of HPD uptake and photosensitization in the brain are discussed.

Journal of Labelled Compounds and Radiopharmaceuticals, 1995

ABSTRACT

Journal of Endodontics, 1984

... Garnet Laser Irradiation Analisis con SEM de la Pared Dentinaria del Conducto Luego de la Irr... more ... Garnet Laser Irradiation Analisis con SEM de la Pared Dentinaria del Conducto Luego de la Irradiacion con Laser Nd-YAG Douglas N. Dederich ... At a series of evenly spaced locations along the canal wall, the concavity was flattened by an inverted cone bur to form small circular ...

Free Radical Biology and Medicine, 1996

Clinical Cancer Research, 2007

Purpose: The study aims to compare the standard/continuous light delivery with fractionated light... more Purpose: The study aims to compare the standard/continuous light delivery with fractionated light delivery for interstitial photodynamic therapy (PDT) of prostate cancer. Experimental Design: Dunning R3327 prostate tumor models were established in male syngeneic rats. When tumors reached f3,000 mm 3 , animals were randomized to various treatment groups. Three hours after QLT0074 injection, tumors were illuminated by 690-nm light delivered by a computer-controlled switch, which sequentially directed light to one of the seven optical fibers in cycles. For comparison, tumors were treated with continuous illumination.Tumors treated with light-only served as control. Dynamic contrast-enhanced magnetic resonance imaging was used to monitor tumor perfusion changes before and after PDT. Results: Tumor response (animal survival) to PDT with fractionated light delivery was PDT dose dependent in both tumor models. Rats bearing anaplastic tumor treated by fractionated light (PDT dose: 1.5 mg/kg QLT0074, 900 J light) had a median survival of 51days with 25% tumor cures compared with that of 26 days with no tumor cure by continuous illumination (P = 0.015) and 14 days by light-only (P = 0.0001). Rats bearing well-differentiated tumor treated by fractionated light had a median survival of 82 days compared with 65 days by continuous illumination (P = 0.001) and 37 days by light-only. PDT with fractionated light generated a perfusion reduction of 80% compared with 52% for continuous illumination in well-differentiated tumors. Conclusions: Fractionated light delivery is more effective than continuous light delivery in PDT of prostate cancer (solid tumors). These results warrant further investigation in clinical trials.

CardioVascular and Interventional Radiology, 2008

Interstitial photodynamic therapy (PDT) selectively destroys tissue targeted with a photosensitiz... more Interstitial photodynamic therapy (PDT) selectively destroys tissue targeted with a photosensitizer and then exposed to light of a specific wavelength. We report a novel delivery method--intra-arterial drug delivery for PDT of the prostate--in a canine model. To evaluate drug distribution, the prostatovesical artery was selectively cannulated and photosensitizers alone or in conjunction with 99m-technetium-labeled macro-aggregated albumin ((99m)Tc-MAA) were injected via a 3 Fr microcatheter in 8 animals. One dog was followed for 3 months to determine tolerance and toxicity. The remaining animals were euthanized and imaged with whole-body single photon emission CT and gamma counting for radioactivity distribution. Photosensitizer distribution was further analyzed by fluorescence confocal microscopy and tissue chemical extraction. To evaluate PDT, the photosensitizer QLT0074 was infused in 3 animals followed by interstitial illumination with 690 nm laser light. Intra-arterial infusion selectively delivered drugs to the prostate, with both radioactivity and photosensitizer levels significantly higher (up to 18 times) than in the surrounding organs (i.e., rectum). With unilateral injection of (99m)Tc-MAA, only the injected half of the prostate showed activity whereas bilateral administration resulted in drug delivery to the entire prostate. PDT resulted in comprehensive damage to the prostate without severe complications or systemic toxicity. Injection of radiolabeled MAA into the prostatovesical artery results in distribution within the prostate with negligible amounts reaching the adjacent organs. PDT also demonstrates selective damage to the prostate, which warrants clinical application in targeted prostate therapies.

Cancer Chemotherapy and Pharmacology, 1996

Hypocrellin compounds were selected as potential photosensitizers for photodynamic therapy (PDT) ... more Hypocrellin compounds were selected as potential photosensitizers for photodynamic therapy (PDT) owing to their high quantum yields of singlet oxygen (O ), and facility for site-directed chemical modification to enhance phototoxicity, pharmacokinetics, solubility, and light absorption in the red spectral region, among other properties. Parent hypocrellins A and B share an absorption peak at 658 nm. These molecules may therefore be considered useful progenitors of derivatives which absorb more strongly in the red, considering that the ideal sensitizer should absorb in the 650-800 nm range, beyond the absorption range of hemoglobin and melanin, and where light penetration in tissues is maximized through reduced scattering. A series of pure, monomeric hypocrellin derivatives was tested for properties of dark cytotoxicity and photosensitizing potential by clonogenic assay in monolayer cultures of EMT6/Ed murine tumor cells. Their respective toxicities are reported on a molar basis. The in vitro screening assay has, to date, resulted in the selection of four hypocrellin derivatives for further development as photosensitizers for PDT. Cellular uptake for photosensitizing doses of selected compounds was determined by fluorimetry. Dose escalation studies in rodents indicate that potentially photosensitizing doses promote no demonstrable systemic toxicity.

Canadian Journal of Microbiology, 1986

The ability of a carbon dioxide laser to sterilize the root canal of human teeth has been investi... more The ability of a carbon dioxide laser to sterilize the root canal of human teeth has been investigated. Three oral bacteria, Streptococcus sanguis, Streptococcus mutans, and Actinomyces viscosus, and three other bacteria, Bacillus cereus, Staphylococcus aureus, and Pseudomonas aeruginosa were used as experimental organisms. Exposure of cells on glass slides to laser radiation showed there was little difference in the exposure required to kill these six organisms. Complete recovery of bacteria from the root canal was initially a problem and was only achieved when bacterial manipulations and removal were carried out in rapid succession, within 5 min of inoculation. However, the geometry of the instrumented canal and the laser alignment were major factors in achieving consistent cell death of oral bacteria in the root canals. Using sets of 10 teeth, four repeated exposures of 10 W for 1 s was found to sterilize 4 or more of the teeth.

Atherosclerosis, 1996

Recurrence of atherosclerotic plaque growth after interventional therapy, restenosis, is a signif... more Recurrence of atherosclerotic plaque growth after interventional therapy, restenosis, is a significant clinical problem occurring in 20%-50% of cases. We have developed a new avian model for the investigation of restenosis after arterial injury in cholesterol fed White Leghorn roosters. Atherosclerotic plaque growth 1-30 weeks after angioplasty balloon mediated endothelial injury in the abdominal aorta was studied in 37 roosters. Roosters were maintained on either normal poultry diet or high cholesterol diet. Twelve cholesterol fed roosters were also fed a hormone supplemented diet in order to modify plaque morphology. The procedural success rate was high. Angiographic stenoses (mean 36% with maximum of 74%) were detectable in cholesterol fed roosters after balloon angioplasty with associated histological evidence of plaque growth (P &amp;lt; 0.017). Cholesterol feeding enhanced fatty plaque growth; hormone manipulation increased calcific and ulcerated plaque but with high associated morbidity. Three interventional devices were subsequently examined in 32 roosters (16 laser angioplasty, 7 atherectomy, and 9 stent implant). Plaque development was again assessed by contrast angiography and histological analysis. We conclude that balloon mediated arterial injury in cholesterol fed roosters produces early proliferative and late, complex atherosclerotic lesions providing an inexpensive model for plaque development after intimal injury.

Applied Physics B, 2008

A method for range-resolved gas sensing using path-integrated optical systems is presented. The m... more A method for range-resolved gas sensing using path-integrated optical systems is presented. The method involves dividing an absorption path into several measurement segments and extracting the gas concentration in each segment from two path-integrated measurements. We implemented the method with tunable lasers (a 1389-nm VCSEL and a 10.9-μm pulsed quantum cascade laser) and a group of retro reflectors (RRs) distributed