Arkady Mandel

Photodynamic inactivation of Staphylococcus aureus and methicillin-resistant Staphylococcus aureus with Ru(II)-based type I/type II photosensitizers

BACKGROUND The introduction of new disinfection and sterilization methods, such as antimicrobial photodynamic therapy, is urgently needed for the healthcare industry, in particular to address the pervasive problem of antibiotic resistance. This study evaluated the efficacy and the mechanisms of photodynamic antimicrobial chemotherapy (PACT), also known as photodynamic inactivation (PDI) of microorganisms, induced by novel Ru(II)-based photosensitizers against Staphylococcus aureus and methicillin-resistant S. aureus strains. METHODS The photodynamic antibacterial effects of a new class of Ru(II)-based photosensitizers (TLD1411 and TLD1433) were evaluated against a strain of S. aureus (ATCC 25923) and a methicillin-resistant strain of S. aureus (MRSA, ATCC 33592). Bacterial samples were dosed with a range of photosensitizer concentrations (0.3-12 μM) and exposed to 530 nm light (90J cm(-2)) in normoxic conditions (ambient atmosphere) and in hypoxic conditions (0.5% O2). RESULTS Both photosensitizers exerted photodynamic inactivation (PDI) of the microorganisms in normoxia, and this activity was observed in the nanomolar regime. TLD1411 and TLD1433 maintained this PDI potency under hypoxic conditions, with TLD1433 becoming even more active in the low-oxygen environment. CONCLUSION The observation of activity in hypoxia suggests that there exists an oxygen-independent, Type I photoprocess for this new class of compounds in addition to the typical Type II pathway mediated by singlet oxygen. The intrinsic positive charge of the Ru(II) metal combined with the oxygen independent activity demonstrated by this class of photosensitizers presents a new strategy for eradicating both gram-positive and gram-negative bacteria regardless of oxygenation level.

Novel Osmium-based Coordination Complexes as Photosensitizers for Panchromatic Photodynamic Therapy

Cancer remains a major global malaise requiring the advent of new, efficient and low‐cost treatments. Photodynamic therapy, which combines a photosensitizer and photons to produce cytotoxic reactive oxygen species, has been established as an effective cancer treatment but has yet to become mainstream. One of the main limitations has been the paucity of photosensitizers that are effective over a wide range of wavelengths, can exert their cytotoxic effects in hypoxia, are easily synthesized and produce few if any side effects. To address these shortfalls, three new osmium‐based photosensitizers (TLD1822, TLD1824 and TLD1829) were synthesized and their photophysical and photobiological attributes determined. These photosensitizers are panchromatic (i.e. black absorbers), activatable from 200 to 900 nm and have strong resistance to photobleaching. In vitro studies show photodynamic therapy efficacy with both red and near‐infrared light in normoxic and hypoxic conditions, which translated to good in vivo efficacy of TLD1829 in a subcutaneous murine colon cancer model.

Laser therapy applications for osteoarthritis and chronic joint pain – A randomized placebo-controlled clinical trial

Abstract Objective: A randomized placebo-controlled clinical trial to evaluate an adjunctive treatment modality for pain associated with knee disorders was conducted utilizing a therapeutic laser system (low energy, non-surgical). Subjects and methods: The therapeutic laser system utilized a dual wavelength, multiple diode laser cluster probe with five super-pulsed 905 nm near-infrared (NIR) laser diodes, each emitting at 40 mW average power and four continuous wave 660 nm visible (VIS) red laser diodes, each emitting at 25 mW. It was used as an adjunctive modality providing 12 treatments, three times a week to a homogeneous patient population (n=126), in combination with standardized chiropractic techniques, to evaluate effectiveness on subjects presenting with osteoarthritis and knee pain. The primary endpoint was measured by the visual analog scale (VAS) to assess pain levels on a scale of 0–10. The success criteria for an individual patient in this study were identified as an improvement of 30% or more in the VAS from baseline to 12th treatment and/or an improvement of 20% or more in the VAS from baseline to 30-day follow-up evaluation. Results: The data obtained in the study demonstrated that the present therapeutic laser system provided significant pain relief and osteoarthritic improvements in all primary evaluation criteria, with a statistical and clinical significance of p<0.01 in VAS from baseline to the 30-day follow-up. Zusammenfassung Zielsetzung: Durchführung einer randomisierten, plazebokontrollierten klinischen Studie zur Evaluation einer begleitenden Schmerzbehandlung bei Knieerkrankungen mit einem nicht-chirurgischen therapeutischen Low-Power-Lasersystem. Patienten und Methode: Zur begleitenden Schmerztherapie kam ein therapeutisches Lasersystem mit dualer Wellenlänge (660 nm/905 nm) zum Einsatz, welches über ein Handstück mit Diodenclustern bestehend aus 5 supergepulsten 905 nm nahinfraroten Laserdioden mit jeweils 40 mW mittlerer Leistung und 4 im sichtbaren Bereich kontinuierlich abstrahlenden 660 nm Laserdioden mit jeweils 25 mW Leistung verfügt. In die Studie eingeschlossen wurden 126 Patienten mit Osteoarthritis und Knieschmerzen, die die Schmerztherapie (12 Behandlungen pro Patient, 3x wöchentliche Anwendung) begleitend zu standardisierten chiropraktischen Techniken erhielten. Primärer Endpunkt der Studie war der subjektive Schmerzlevel, der anhand der visuellen Analogskala (visual analog scale, VAS; von 1 bis 10) gemessen wurde. Als Erfolgskriterien wurden bestimmt entweder eine 30%-ige Verbesserung der VAS-Werte nach der 12. Behandlung oder eine 20%-ige Verbesserung der VAS-Werte innerhalb der Follow-up-Periode von 30 Tagen jeweils im Vergleich zu den Anfangswerten zu Beginn der Behandlung. Ergebnisse: Die Studiendaten haben gezeigt, dass mit dem verwendeten therapeutischen Lasersystem eine Schmerzlinderung sowie eine Verbesserung der arthrotischen Beschwerden mit einer statistischen Signifikanz von p<0.01 erzielt werden konnte (Reduzierung der VAS-Werte vom Beginn der Therapie bis 30 Tage nach Behandlung).

Kynetic resazurin assay (KRA) for bacterial quantification of foodborne pathogens

Fast detection of bacterial concentrations is important for the food industry and for healthcare. Early detection of infections and appropriate treatment is essential since, the delay of treatments for bacterial infections tends to be associated with higher mortality rates. In the food industry and in healthcare, standard procedures require the count of colony-forming units in order to quantify bacterial concentrations, however, this method is time consuming and reports require three days to be completed. An alternative is metabolic-colorimetric assays which provide time efficient in vitro bacterial concentrations. A colorimetric assay based on Resazurin was developed as a time kinetic assay (KRA) suitable for bacterial concentration measurements. An optimization was performed by finding excitation and emission wavelengths for fluorescent acquisition. A comparison of two non-related bacteria, foodborne pathogens Escherichia coli and Listeria monocytogenes, was performed in 96 well plates. A metabolic and clonogenic dependence was established for fluorescent kinetic signals.

Targeting non-small cell lung cancer by novel TLD-1433-mediated photodynamic therapy (Conference Presentation)

Background: The majority of cancers upregulate their transferrin receptor (Tf-R) to satisfy their higher Fe3+ requirements for proliferation. TLD-1433 can bind to transferrin to form Rutherrin, which is a promising photosensitizer with stable chemical structure and higher tissue selectivity. Methods: To investigate the effect of Rutherrin®-mediated photodynamic treatment (PDT), we used non-small lung cancer cell lines H2170, A549, and H460. Subcutaneous tumors were treated with Rutherrin-mediated PDT, 4hrs post intravenous administration. The treatment parameters10 mg/kg Rutherrin and 600 Jcm-2 808 nm radiation. In an orthotopic A549 tumor model, the presence of tumor after inoculation in lungs was confirmed by microCT. Tissue samples were collected for Inductively Coupled Mass Spectrometry to quantify the Rutherrin concentrations via a Ru isotope in tumor and normal lung tissue. Results: Evaluation of TfR expression by flow cytometric and western blotting showed that almost all cancer cells express TfR. In in-vitro cytotoxicity assay, all cancer cell lines showed high cell kill by PDT at 100nM Rutherrin concentrations. In the subcutaneous tumor model, PDT after Rutherrin injection significantly inhibited the tumor growth and histopathology showed extensive necrosis at 24 hrs, which was confirmed with lowered Ki67 staining. In an orthotopic model, the lung lobe with tumor retained more Rutherrin than the contralateral lung, showing specific tumor uptake. Conclusion: These results support the hypothesis that safe and efficient Rutherrin-mediated PDT is feasible due to improved photosensitizer localization to lung tumors tissue. Selective irradiation of the cancer lesions by strategic placement of the light source remains a requirement.

Correlation of intracellular oxygen and cell metabolism by simultaneous PLIM of phosphorescent TLD1433 and FLIM of NAD(P)H

During photodynamic therapy (PDT), disruption of cell respiration and metabolic changes could be one of the first events. Photophysical characteristics of the photosensitizer (PS) and its specific redox potential define consumption of molecular oxygen followed by generation of reactive oxygen species. The potential PS TLD1433 is based on transition metal Ru(II) and possess an oxygen-dependent luminescence. This enables the study of oxygen consumption by PS-phosphorescence lifetime imaging (PLIM) and simultaneously changes the cellular metabolic state by nicotinamide adenine dinucleotide (NAD(P)H)-fluorescence lifetime imaging (FLIM). Within this study, localization and cellular function of TLD1433 is investigated in bladder carcinoma cells using time-resolved and confocal laser scanning microscopy. Simultaneous FLIM/PLIM of NAD(P)H and TLD1433 during PDT correlated oxygen consumption, redox state and cellular energy metabolism. Our investigations aimed to provide a personalized protocol in theranostic PDT procedures and demonstrate the potential use of TLD1433 PDT also under hypoxic conditions, which are otherwise difficult to treat.

Role of iNOS gene expression in the anti-inflammatory and tissue protective mechanisms of continuous wave at 630-905nm and 905nm superpulsed laser therapy

Up regulation of iNOS gene expression is playing a role in the initiation of the anti-inflammatory and tissue protective mechanisms related to nitric oxide (NO) for continuous wave red and infrared as well as 905nm superpulsed laser therapy (SPLT). The iNOS expression before and after laser therapy was evaluated in a zymosan-induced acute arthritis model, in knee joints of young (<15 weeks), middle aged (>15 weeks and < 35 weeks) and old (> 35 weeks) FVB/N-Tg (iNOS-luc) mice by bioluminescence imaging.