Protoporphyrin IX

About: Protoporphyrin IX is a research topic. Over the lifetime, 2250 publications have been published within this topic receiving 65544 citations. The topic is also known as: PpIX.

Fluorescence spectroscopy combined with 5-aminolevulinic acid induced protoporphyrin IX fluorescence in detecting oral premalignancy

Abstract: BACKGROUND Early detection of premalignant/malignant lesions in the oral cavity can certainly improve the patient's prognosis. This study presents fluorescence imaging with the topical application of 5-aminolevulinic as a way to improve detection of various oral tissue pathologies. This procedure depends mainly on comparing the intensity of red and green fluorescence emitted from tissues during examination. MATERIALS AND METHODS Seventy-one patients who presented with clinically suspicious oral leukoplakia were recruited for this study. Each of the patients was required to have 5-aminolevulinic acid in the form of mouth rinse prior to fluorescence imaging. Following this a surgical biopsy was acquired from the exact examination site. The results of the fluorescence spectroscopy have been compared with histopathology. RESULTS A Student's t-test was applied to test the viability of the ratio between red and green fluorescence. The red-to-green ratio was found to increase significantly when the lesion was identified as dysplastic or carcinoma in situ. By applying a threshold line to discriminate between normal and dysplastic lesions; a sensitivity of 83-90% and specificity of 79-89% were obtained. CONCLUSION Fluorescence spectroscopy combined with 5-aminolevulinic acid-induced protoporphyrin IX was found as a valuable tool in the diagnosis of oral premalignancy. This technique offers the potential to be advantageous over other non-optical techniques in terms of providing real-time diagnosis, in situ monitoring, cost effectiveness and more tolerated by patient compared to surgical biopsy.

Monitoring In Situ Dosimetry and Protoporphyrin IX Fluorescence Photobleaching in the Normal Rat Esophagus During 5-Aminolevulinic Acid Photodynamic Therapy {

Abstract: Experimental therapies for Barrett's esophagus, such as 5-aminolevulinic acid (ALA)–based photodynamic therapy (PDT), aim to ablate the premalignant Barrett's epithelium. However, the reproducibility of the effects should be improved to optimize treatment. Accurate irradiation with light of a proper wavelength (633 nm), fluence and fluence rate has shown to be critical for successful ALA-PDT. Here, we have used in situ light dosimetry to adjust the fluence rate measured within the esophagus for individual animals and monitored protoporphyrin IX (PpIX) fluorescence photobleaching simultaneously. Rats were administered 200 mg kg–1 ALA (n = 14) or served as control (n = 7). Animals were irradiated with an in situ measured fluence rate of 75 mW cm–2 and a fluence of 54 J cm–2. However, this more accurate method of light dosimetry did not decrease the variation in tissue response. Large differences were also observed in the dynamics of PpIX fluorescence photobleaching in animals that received the same...

Formation of a Porphyrin Monolayer Film by Axial Ligation of Protoporphyrin IX Zinc to an Amino-Terminated Silanized Glass Surface

Abstract: A porphyrin covalently appended monolayer film on a glass substrate prepared by axial coordination reaction of protoporphyrin IX zinc (ZnPP) and a self-assembled monolayer of (3-aminopropyl)trimeth...

Pharmacology of protoporphyrin IX in nude mice after application of ALA and ALA esters.

Abstract: Aminolevulinic acid (ALA), ALA methylester (ALA-Me) and ALA hexylester (ALA-Hex) were topically applied for 5 and 20 hr, respectively, on normal skin of mice. The distribution of protoporphyrin IX (PpIX) induced in 7 different tissues by these drugs was determined either by spectrofluorometric measurements with an optical fibre probe or by chemical extraction of PpIX from the tissues. The results from these 2 types of measurements were compared. Both methods showed that ALA and the esters induced similar amounts of PpIX at the skin spot where they were applied and that the esters produced much less PpIX at remote skin spots (i.e., spots outside the location where the drugs were applied) than ALA did, notably after 20 hr application. After 20 hr of drug application ALA produced much more PpIX in liver, intestine and lungs than the esters did. In contrast with the direct fluorescence measurements, the extraction method showed detectable amounts of PpIX in liver, intestine and lung after application of the esters, notably of ALA-Me. The discrepancy is probably related to the fact that the pigmented tissues absorb light and, therefore, the direct fluorescence readings are misleading. Notably in the liver, which contains high concentration of light-absorbing pigments, very weak direct fluorescence was seen. In no case there was any accumulation of PpIX in muscle tissue nor in brain. The esters seem to penetrate less into the circulation than ALA, and PpIX formed by them in the skin is faster cleared than PpIX formed from ALA. This is also true after oral and i.p. administration of the drugs. © 2002 Wiley-Liss, Inc.