Norbert Lange | Université de Genève (original) (raw)

Papers by Norbert Lange

Photodiagnosis and photodynamic therapy, Jan 15, 2015

In dentistry, antibacterial photodynamic therapy (a-PDT) has shown promising results for inactiva... more In dentistry, antibacterial photodynamic therapy (a-PDT) has shown promising results for inactivating bacterial biofilms causing carious, endodontic and periodontal diseases. In the current study, we assessed the ability of eosin Y exposed to 3 irradiation protocols at inactivating E. faecalis biofilms, in vitro. E. faecalis biofilms formed on hydroxyapatite discs were incubated with eosin Y (10-80μM), then activated with blue light using different irradiation protocols. Biofilms exposed to continuous exposure were incubated for 40min before being light-activated for 960 s. For the intermittent exposure, biofilms were exposed 4 times to the light /photosensitizer combination (960 s total) without renewing the photosensitizer. For repeated a-PDT, the same light dose was delivered in a series of 4 irradiation periods separated by dark periods; fresh photosensitizer was added between each light irradiation. After treatment, bacteria were immediately labeled with LIVE/DEAD BacLight Bact...

Section des sciences pharmaceutiques Professeur Robert GURNY Laboratoire de pharmacie galénique D... more Section des sciences pharmaceutiques Professeur Robert GURNY Laboratoire de pharmacie galénique Docteur Norbert LANGE et de biopharmacie Je tiens à exprimer mes sincères remerciements au Professeur Robert Gurny, pour m'avoir accueilli dans son laboratoire de pharmacie galénique à l'Université de Genève, et de m'avoir permis de disposer de conditions de travail idéales. Je témoigne ma gratitude au membres du jury qui ont aimablement accepté de lire, évaluer et critiquer mon travail de thèse : Le docteur Marie-Ange d'Hallewin du Centre Alexis Vautrin à Nancy, le docteur Angelika Rueck de l'Institut des technologies laser médicales à

5-Aminolevulinic acid (5-ALA)-mediated photodynamic therapy has been proposed as an alternative, ... more 5-Aminolevulinic acid (5-ALA)-mediated photodynamic therapy has been proposed as an alternative, cervix-sparing treatment for cervical intraepithelial neoplasia (CIN). In this context, topical application of 5-ALA to the cervix is beneficial due to the small necessary dose and its minimal side effects. Therefore, lipophilic 5-ALA esters, such as hexylaminolevulinate (HAL), have led to improved local bioavailability and therapeutic efficacy. Hydrogels have shown to be more appropriate for the local delivery of these derivatives, but due to the limited long-term stability of such formulations at 258C, the development of an extemporaneously prepared hydrogel targeting CIN can be advantageous. Therefore, a poloxamer 407 thermosetting gel, which is liquid at room temperature and becomes a semi-solid when in contact with the female genital tract, has been evaluated in vitro and in vivo. Rheological evaluation has shown that a 17.0% poloxamer 407 hydrogel with a sol-gel transition at 24.8 AE 0.68C was the best formulation for easy application and optimal residence time. Furthermore, similarly to other hydrogels previously tested, such a formulation shows a more complete HAL release in vitro than conventional cream vehicles, and tends to increase porphyrin accumulation in nude mice skin. Finally, in vitro release profiles were correlated to the in vivo results.

Journal of Endodontics, 2014

Introduction: Pulp repair is less likely to occur when dentin or pulpal tissue remains infected a... more Introduction: Pulp repair is less likely to occur when dentin or pulpal tissue remains infected after caries excavation. Yet there are currently few options to kill residual bacteria without damaging resident cells. The current study has evaluated the effect of 3 blue light-activated chemicals on the viability of lactobacilli, odontoblast-like cells (MDPC-23), undifferentiated pulp cells (OD21), and human embryonic stem cells (hESC H1). Methods: Bacteria were incubated for 15 minutes with curcumin, eosin Y, or rose bengal and then irradiated with blue light (240 seconds). Bacteria were labeled with LIVE/ DEAD BacLight Bacterial Viability kit, and viability was assessed by fluorescence-activated cell sorting. Cytotoxicity assays were performed on MDPC-23 cells, OD21, and hESC H1 cells grown in 24-well plates and exposed to the same photosensitizer-light combination. After 24 hours, cellular response was measured by using the methyl-thiazol-diphenyl-tetrazolium assay. Results were statistically analyzed by using one-way analysis of variance and Tukey multiple comparison intervals (a = 0.05). Results: Bacterial viability was significantly reduced after exposure to different combinations of light and photosensitizers; mitochondrial activity of cultured cells remained unaffected when exposed to the same conditions, suggesting a good therapeutic index in vitro. Conclusions: Blue light-mediated disinfection is promising for the development of new treatment strategies designed to promote pulp repair after carious exposure. (J Endod 2014;-:1-5)

Pharmaceutical Research, 2004

In topical photodynamic therapy, 5-ALA and its esters are enzymatically converted in the endogeno... more In topical photodynamic therapy, 5-ALA and its esters are enzymatically converted in the endogenous photosensitizing compounds such as, for example, protoporphyrin IX (PpIX). In order to elucidate in more detail their enzymatic fate, we have determined in vitro the enzymatic degradation of methyl, butyl, hexyl, and octyl-5-ALA ester derivatives in skin homogenate. Furthermore, in vivo porphyrin accumulation was measured in healthy hairless mice skins. Hairless mouse skins were homogenized in isotonic phosphate buffer pH 7.4. 5-ALA esters were added, and aliquots were colleted for HPLC-fluorimetric determinations of remaining content of 5-ALA esters. Furthermore, oil-in-water emulsions containing esters were topically applied to mice skin for 6 h, and the amount of accumulated PpIX in the treated areas was determined by quantitative extraction and confocal fluorescence microscopy. The enzymatic degradation of esters follows pseudo first-order kinetics. The octyl ester had the largest rate constant for enzymatic degradation, followed by hexyl-, butyl-, and methyl-ALA. The long-chained 5-ALA esters, butyl-, hexyl-, and octyl ester, induced significantly more porphyrins than 5-ALA and 5-ALA methyl ester as shown by confocal microscopy and quantitative extraction studies. 5-ALA derivatives differ widely with respect to their enzymatic degradation. The presence of alkyl chains in 5-ALA esters significantly influences the in vitro enzymatic metabolism and the in vivo PpIX formation in healthy hairless mice skins.

Journal of Photochemistry and Photobiology B: Biology, 2008

Basal cell carcinoma (BCC) Photodynamic therapy (PDT) 5-aminolevulinic acid (ALA) 5-aminolevulini... more Basal cell carcinoma (BCC) Photodynamic therapy (PDT) 5-aminolevulinic acid (ALA) 5-aminolevulinic acid ester (ALA-ester) Protoporphyrin IX (PpIX) Fluorescence spectroscopy a b s t r a c t Photodynamic therapy (PDT) based on the use of photoactivable porphyrins, such as protoporphyrin IX (PpIX), induced by the topical application of amino-levulinic acid (ALA) or its derivatives, ALA methylester (m-ALA), is a treatment for superficial basal cell carcinoma (BCC), with complete response rates of over 80%. However, in the case of deep, nodular-ulcerative lesions, the complete response rates are lower, possibly related to a lower bioavailability of PpIX. Previous in vitro skin permeation studies demonstrated an increased penetration of amino-levulinic acid hexyl-ester (h-ALA) over ALA. In this study, we tested the validity of this approach in vivo on human BCCs. An emulsion containing 20% ALA (w/w) and preparations of h-ALA at different concentrations were applied topically to the normal skin of Caucasian volunteers to compare the PpIX fluorescence intensities with an optical fiber-based spectrofluorometer. In addition, the PpIX depth distribution and fluorescence intensity in 26 BCCs were investigated by fluorescence microscopy following topical application of 20% ALA and 1% h-ALA. We found that, for application times up to 24 h, h-ALA is identical to ALA as a PpIX precursor with respect to PpIX fluorescence intensity, depth of penetration, and distribution in basal cell carcinoma, but has the added advantage that much smaller h-ALA concentrations can be used (up to a factor 13). We observed a non-homogenous distribution in BCCs with both precursors, independent of the histological type and depth of invasion in the dermis.

Journal of Drug Targeting, 2009

Biodegradable polymeric nanoparticles (NP) are promising delivery systems for photosensitizers (P... more Biodegradable polymeric nanoparticles (NP) are promising delivery systems for photosensitizers (PS). A hydrophobic PS, the meso-tetra(p-hydroxyphenyl)porphyrin (m-THPP) was encapsulated into NP made of poly(D,L-lactide-co-glycolide) using an emulsification-diffusion method, and poly(vinyl alcohol) (PVAL) as stabilizing agent during the emulsification step. Three batches of NP with mean diameters of 117, 285, and 593 nm, respectively, were prepared. NP of 117 nm exhibited the highest rate of reactive oxygen species production and the fastest m-THPP release determined by the transfer of m-THPP to serum proteins in vitro. Similarly, the 117 nm batch exhibited the highest in vivo photodynamic activity, as established in the chick embryo chorioallantoic membrane model. Our data suggest that m-THPP release before illumination is an important step for in vivo photodynamic activity especially for large NP. The NP size and the amount of residual PVAL at the NP surface were shown to control both the PS release and activity.

Journal of Dermatological Science, 2009

Journal of Controlled Release, 2012

We have developed a thrombin-sensitive polymeric photosensitizer prodrug (T-PS) to selectively im... more We have developed a thrombin-sensitive polymeric photosensitizer prodrug (T-PS) to selectively image and eradicate inflammatory lesions in rheumatoid arthritis (RA). Thrombin is a serine protease up-regulated in synovial tissues of rheumatoid arthritis (RA) patients. T-PS consists of a polymeric backbone, to which multiple photosensitizer (PS) units are tethered via short thrombin-cleavable peptide linkers. Fluorescence emission and phototoxicity of the prodrug are efficiently quenched due to the interaction of neighboring photosensitizer units. The prodrug is passively delivered to the inflammation site via the enhanced permeability and retention (EPR) effect. Subsequent site-selective proteolytic cleavage of the peptide linkers restores its photoactivity by increasing the mutual distance between PS. Whole animal imaging in murine collagen-induced arthritis, an experimental model of RA revealed a dose-dependent fluorescence increase in arthritic paws after systemic prodrug injection. In addition, administration of T-PS resulted in much higher fluorescence selectivity for arthritic joints as compared to the free PS. Irradiation of the arthritic joints induced light dose dependent phototoxic effects such as apoptosis, vascular damage and local hemorrhage. Long-term observations showed complete regression of the latter. Irradiated non-arthritic tissues or non-irradiated arthritic tissues showed no histological effects after photodynamic therapy with T-PS. This illustrates that T-PS can localize inflammatory lesions with excellent selectivity and induce apoptosis and vascular shut down after irradiation.

Journal of Controlled Release, 2007

Fluorescence diagnosis following oral administration of 5-aminolevulinic acid (5-ALA) has shown t... more Fluorescence diagnosis following oral administration of 5-aminolevulinic acid (5-ALA) has shown to enable the sensitive visualization of intestinal metaplasia, dysplasia and early carcinoma in Barrett's esophagus. Once being established, this technique will be a potential alternative to today's standard diagnosis, i.e. four-quadrant random biopsies which are taken every 1-2 cm of the esophagus for histopathological analysis. In order to further improve this methodology, topical application of lipophilic 5-ALA esters to the esophagus could be advantageous in terms of fluorescence contrast and fluorescence intensity in the target tissue, adverse side effects, as well as application time. Therefore, the aim of this study was to develop a bioadhesive formulation loaded with hexylaminolevulinate (HAL) targeting the esophageal lining. In the present study, different mucoadhesive gels including poloxamer 407, cross-linked polyacrylic acid, hydroxypropylmethylcellulose, sodium carboxymethylcellulose and chitosan have been evaluated with respect to bioadhesion to the esophagus using an ex vivo rat model and a clinical study on healthy volunteers. In order to visualize the mucoadhesive properties of the formulations, a blue dye was incorporated as contrast agent. Chitosan has shown the best esophageal adhesion both in vitro and in vivo. Furthermore, using the in vitro release profiles from chitosan loaded with 40 mM of HAL, one can estimate that after a residence time of 10 min on the esophageal wall, the amount of HAL delivered to the epithelium will be sufficient to perform fluorescence diagnosis of Barrett's esophagus following swallowing of this formulation.

Expert Review of Clinical Immunology, 2011

Photodynamic therapy (PDT) is a rapidly developing cancer treatment that utilizes the combination... more Photodynamic therapy (PDT) is a rapidly developing cancer treatment that utilizes the combination of nontoxic dyes and harmless visible light to destroy tumors by generating reactive oxygen species. PDT produces tumor-cell destruction in the context of acute inflammation that acts as a 'danger signal' to the innate immune system. Activation of the innate immune system increases the priming of tumor-specific T lymphocytes that have the ability to recognize and destroy distant tumor cells and, in addition, lead to the development of an immune memory that can combat recurrence of the cancer at a later point in time. PDT may be also successfully combined with immunomodulating strategies that are capable of overcoming or bypassing the escape mechanisms employed by the progressing tumor to evade immune attack. This article will cover the role of the immune response in PDT anti-tumor effectiveness. It will highlight the milestones in the development of PDT-mediated anti-tumor immunity and emphasize the combination strategies that may improve this therapy.

Endoscopy, 2003

Barrett&amp;amp;amp;amp;amp;#39;s esophagus is strongly associated with adenocarcinoma. E... more Barrett&amp;amp;amp;amp;amp;#39;s esophagus is strongly associated with adenocarcinoma. Early malignant transformation of the Barrett&amp;amp;amp;amp;amp;#39;s mucosa is often not visible endoscopically and may remain undetected until the invasive adenocarcinoma stage. Endoscopic surveillance is currently carried out on random four-quadrant biopsies at 1-2 cm intervals. Endoscopic fluorescence detection of protoporphyrin IX induced by 5-aminolevulinic acid can identify premalignant lesions. This study evaluates endoscopic fluorescence detection in patients having Barrett&amp;amp;amp;amp;amp;#39;s esophagus and compares the results to those of standard endoscopy with random four-quadrant biopsies. The study included 30 examinations in 28 patients (22 men, 6 women; age range 37-78 years, mean age 60 years,), with five patients having known intraepithelial neoplasia. A dose of 20 mg/kg of 5-aminolevulinic acid was given orally 5 hours before examination. Random four-quadrant biopsies were performed 4-6 weeks before endoscopic fluorescence detection. Of the biopsies taken during the endoscopic fluorescence detection procedure, 28 % (23/81) were true positives. More than one-third of the false-positive results were due to inflammation. None of the 97 control biopsies taken on nonfluorescing areas during endoscopic fluorescence detection were dysplastic. Endoscopic fluorescence detection showed low-grade intraepithelial neoplasia in five patients which was not diagnosed with random four-quadrant biopsies, while random four-quadrant biopsies alone showed three low-grade intraepithelial neoplasias that were invisible during endoscopic fluorescence detection. All high-grade intraepithelial neoplasias or adenocarcinomas (2/2) were detected with both methods. Fluorescence detection achieved a similar performance when compared with four-quadrant random biopsy, but resulted in fewer biopsies (81 for endoscopic fluorescence detection vs 531 for random four-quadrant biopsies).

International Journal of Pharmaceutics, 2006

A photodynamic approach has been suggested to improve diagnosis and therapy of ovarian cancer. As... more A photodynamic approach has been suggested to improve diagnosis and therapy of ovarian cancer. As Hypericin (Hy), a natural photosensitizer (PS) extracted from Hypericum perforatum, has been shown to be efficient in vitro and in vivo for the detection or treatment of other cancers, Hy could also be a potent tool for the treatment and detection of ovarian cancer. Due to its hydrophobicity, systemic administration of Hy is problematic. Thus, polymeric nanoparticles (NPs) of polylactic acid (PLA) or polylactic-co-glycolic acid (PLGA) were used as a drug delivery system. Hy-loaded NPs were produced with the following characteristics: (i) size in the 200-300 nm range, (ii) negative zeta potential, (iii) low residual PVAL and (iv) drug loading from 0.03 to 0.15% (w/w). Their in vitro photoactivity was investigated on the NuTu-19 ovarian cancer cell model derived from Fischer 344 rats and compared to free drug. Hy-loaded PLA NPs exhibited a higher photoactivity than free drug. Increasing light dose or incubation time with cells induced an enhanced activity of Hy-loaded PLA NPs. Increased NP drug loading had a negative effect on their photoactivity on NuTu-19 cells: at the same Hy concentration, the higher was the drug loading, the lower was the phototoxic effect. The influence of NP drug loading on the Hy release from NPs was also investigated.