13 research outputs found
Application of UV-radiation and UV-responsive nanocapsules for skin antisepsis
Angesichts der weltweiten Belastung des Gesundheitswesens durch postoperative Wundinfektionen (SSI) und der steigenden PrĂ€valenz multiresistenter Bakterien, war das Ziel dieser Dissertation die Umsetzung zweier neuartiger und innovativer AnsĂ€tze fĂŒr eine verbesserte Hautantisepsis. Haarfollikel stellen ein dicht kolonisiertes Erregerreservoir dar. Bei langwierigen chirurgischen Eingriffen kann es daher zu einer Rekolonisierung der HautoberflĂ€che aus diesem Reservoir, und der Verschleppung potenzieller Krankheitserreger in das Operationsgebiet, kommen. Es ist bekannt, dass SSI in 90% aller FĂ€lle durch endogene Keime verursacht werden. Daraus ergeben sich zwei mögliche AnsĂ€tze fĂŒr eine verbesserte Hautantisepsis: die Dekontamination tiefer Bereiche der Haarfollikel und die wiederholte intraoperative Dekontamination der Haut. Der erste Teil dieser Dissertation zielte auf die Anwendung eines pharmazeutisch basierten Ansatzes zur verbesserten Hautantisepsis ab. Basierend auf dem so genannten Ratscheneffekt dringen Nanopartikel in Haarfollikel ein, wenn Ă€uĂere KrĂ€fte auf sie einwirken. So ist bekannt, dass mit Nano-Delivery-Systemen eine deutlich tiefere follikulĂ€re Penetration von Therapeutika erreicht werden kann als mit der Anwendung von freien Wirkstofflösungen. Eine gezielte Eradikation könnte also durch eine kontrollierte Freisetzung von Antiseptika in den tieferen Segmenten der Haarfollikel erfolgen, wĂ€hrend diese Segmente fĂŒr nicht partikulĂ€re Substanzen unzugĂ€nglich sind. FĂŒr eine gezielte und schnelle Freisetzung des in den Nanokapseln (NCs) enthaltenen Antiseptikums wurde Ultraviolett A (UVA) Licht verwendet, da es die dermalen Hautbereiche erreichen kann. Dieser Ansatz wurde mit UVA Licht emittierenden Dioden (LED) sowie biokompatiblen photoresponsiven NCs verfolgt. Die erste von zwei Studien konzentrierte sich auf Prinzipexperimente zum Nachweis der Möglichkeit einer follikulĂ€ren Penetration und intrafollikulĂ€ren UV-getriggerten Wirkstofffreisetzung unter Verwendung von biokompatiblen Polyurethan (PU)-NCs. Anhand eines ex vivo Schweinehautmodells wurde ein UVA-abhĂ€ngiger Abbau der NCs bei einer mittleren follikulĂ€ren Eindringtiefe von etwa 500 ”m festgestellt, wobei der Modellwirkstoff Sulforhodamin 101 (SR101) in kryohistologischen Schnitten mit konfokaler Laser-Scanning-Mikroskopie (CLSM) verfolgt wurde. In einem weiteren Ansatz wurden HydroxyethylstĂ€rke (HES)-NCs verwendet, die auf der gleichen Technologie basierten. Mit diesen konnte eine vergleichbare follikulĂ€re Eindringtiefe erreicht werden. In einem abschlieĂenden Experiment, bei dem HES-NCs mit eingekapseltem Ethanol verwendet wurden, konnte hinsichtlich der Dekolonisierung kein signifikanter Unterschied zu einer partikelfreien Kontrolle (80% Ethanol) auf der ex vivo Schweineohrhaut festgestellt werden, was zeigt, dass die Wahl der NanotrĂ€germaterialien immer mit dem Anwendungsbereich und der KompatibilitĂ€t mit der kontinuierlichen Phase abgestimmt werden sollte.
ErgĂ€nzend dazu stellt Fern-UVC-Licht (UVC unter einer WellenlĂ€nge von 240 nm) den zweiten Ansatz zur Dekontamination der HautoberflĂ€che dar, da es sich sehr leicht sequentiell anwenden lĂ€sst und somit rekolonisierte FlĂ€chen schnell desinfizieren kann um SSI zu verhindern. Fern-UVC-Strahlung hat aufgrund ihrer hohen Energie den Vorteil, dass sie resistenzfrei Pathogene durch die sofortige Erzeugung von DNA-LĂ€sionen inaktiviert. Im Gegensatz zur UVC-Strahlung von 254 nm, die meist zur Desinfektion von Wasser und OberflĂ€chen eingesetzt wird, wird sie in der obersten, nicht nukleierten Schicht der Haut, dem Stratum corneum, stark absorbiert. Daher ist die Penetration von Fern-UVC-Photonen in die Lebendepidermis nur begrenzt möglich. Im Rahmen dieser Arbeit wurde eine neuartige LED, die Fern-UVC-Licht mit einer Peak-WellenlĂ€nge von 233 nm emittiert, an verschiedenen Hautmodellen hinsichtlich der Bildung von DNA-SchĂ€den und freien Radikalen umfassend auf ihre HautvertrĂ€glichkeit geprĂŒft. Dabei wurden zuvor von den Projektpartnern der UniversitĂ€tsmedizin Greifswald ermittelte mikrobiozide Dosen eingesetzt. Bei einer Anwendungsdosis von 40 bis 60 mJ/cm2 konnte eine vollstĂ€ndige Eradikation von Methicillin-resistenten Staphylococcus aureus (MRSA) auf Agarplatten und KeimtrĂ€gern beobachtet werden. Die Bestrahlung mit mikrobiozidem 233 nm Fern-UVC fĂŒhrte zu geringeren DNA-SchĂ€den in intakter ex vivo Humanhaut im Vergleich zu 10% einer minimalen Erythemdosis (MED) UVB-Strahlung. DarĂŒber hinaus war die Bildung freier Radikale in rekonstruierten humanen Epidermismodellen geringer als bei sichtbarer und nahinfraroter (VISâNIR) Bestrahlung, die einem 20-minĂŒtigen Aufenthalt in der Mittagssonne entspricht. Um der Frage nachzugehen, ob 233 nm Fern-UVC-Strahlung auch wĂ€hrend chirurgischer Eingriffe an Wunden angewandt werden kann, wurde in der Folgestudie ein ex vivo Wundmodell zur Risikobeurteilung von 233 nm Fern-UVC-Strahlung untersucht. Hier wurde nach Bestrahlung mit 233 nm Fern-UVC eine Zunahme und Verlagerung von DNA-LĂ€sionen in tiefere Bereiche der wunden Haut beobachtet. Interessanterweise fĂŒhrte das Auftragen von kĂŒnstlichem Wundexsudat auf die exponierte Lebendepidermis vor der Bestrahlung zur Nachahmung der photoprotektiven Funktion eines intakten Stratum corneum. DarĂŒber hinaus wurde festgestellt, dass in der Wunde eine gewisse Menge an freien Radikalen gebildet wird, was die Wundheilung unterstĂŒtzen könnte. Um den Einfluss der Melaninkonzentration zu ermitteln, wurde menschliche Haut verschiedener Hauttypen ex vivo mit 222 nm und 233 far-UVC-Licht sowie mit breitbandigem UVB-Licht bestrahlt. In dieser Studie zeigte sich, dass die Bildung von DNA-LĂ€sionen bei dunklen Hauttypen nach Bestrahlung mit 233 nm geringer war als bei hellen Hauttypen. Die Bestrahlung bei 222 nm verursachte jedoch aufgrund ihrer begrenzten Eindringtiefe keine hauttypabhĂ€ngigen Unterschiede. Im Gegensatz dazu verursachte UVB eine starke Divergenz zwischen hellen und dunklen Hauttypen bei der Anwendung von 10% einer MED. Die Melaninkonzentration unterscheidet sich zwischen hellen und dunklen Hauttypen in der oberen Epidermis weniger als in den tiefen Schichten der Epidermis. Dies fĂŒhrt, basierend auf der maximalen Eindringtiefe der jeweiligen WellenlĂ€nge, zu hauttypabhĂ€ngigen Abweichungen in der VertrĂ€glichkeit der Strahlung.
Zusammenfassend lĂ€sst sich sagen, dass der in dieser Dissertation untersuchte nanopartikelbasierte Ansatz zur Hautdekolonisierung durch den Fern-UVC-Licht-basierten Ansatz sinnvoll ergĂ€nzt wird und beide AnsĂ€tze Potenzial fĂŒr eine prĂ€operative sowie intraoperative Hautantiseptik besitzen. Dennoch mĂŒssen fĂŒr eine endgĂŒltige Umsetzung noch deutliche Optimierungen auf pharmazeutischer Seite gesucht werden. Der Einsatz von Fern-UVC-LEDs zur Dekontaminierung der HautoberflĂ€che wurde in der vorliegenden Arbeit erstmals umfassend behandelt. Auch hier mĂŒssen fĂŒr die endgĂŒltige Umsetzung weitere Studien zur Risikobewertung durchgefĂŒhrt werden
Follicular Delivery of Caffeine from a Shampoo for Hair Retention
A key factor in the prevention of hair loss is the provision of optimal conditions on the scalp. In this regard, reduction of oxidative stress on the scalp is one critical requirement to support the hair follicles to function optimally. Recently, a novel shampoo formulation technology containing anti-oxidants such as piroctone olamine has been demonstrated to improve hair retention based on micellar degradation and coacervation effects. Caffeine has also been shown to exhibit anti-oxidant activity including the ability to inhibit lipid peroxidation. As with piroctone olamine, it is expected that follicular delivery of caffeine will enhance its anti-oxidant activity in a region that will be beneficial for hair retention. In this study, two shampoo formulations as well as a control formulation were applied to the calf area of n = 9 male participants. The technique of differential tape stripping was applied to obtain the caffeine penetrated to the stratum corneum and to the hair follicles. Isotope-dilution liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was performed to demonstrate caffeine follicular delivery from the shampoo formulas. The results showed that the percentage of caffeine recovered in the hair follicles was 8â9% of the caffeine absorbed into the skin and matched an existing caffeine-based shampoo. In conclusion, a novel shampoo formulation technology has been developed that effectively delivers beneficial anti-oxidants to improve hair retention. This new shampoo is expected to be especially useful in the goal of retaining hair during aging
Riociguat treatment in patients with chronic thromboembolic pulmonary hypertension: Final safety data from the EXPERT registry
Objective: The soluble guanylate cyclase stimulator riociguat is approved for the treatment of adult patients with pulmonary arterial hypertension (PAH) and inoperable or persistent/recurrent chronic thromboembolic pulmonary hypertension (CTEPH) following Phase
Penetration Depth of Propylene Glycol, Sodium Fluorescein and Nile Red into the Skin Using Non-Invasive Two-Photon Excited FLIM
The stratum corneum (SC) forms a strong barrier against topical drug delivery. Therefore, understanding the penetration depth and pathways into the SC is important for the efficiency of drug delivery and cosmetic safety. In this study, TPT-FLIM (two-photon tomography combined with fluorescence lifetime imaging) was applied as a non-invasive optical method for the visualization of skin structure and components to study penetration depths of exemplary substances, like hydrophilic propylene glycol (PG), sodium fluorescein (NaFl) and lipophilic Nile red (NR) into porcine ear skin ex vivo. Non-fluorescent PG was detected indirectly based on the pH-dependent increase in the fluorescence lifetime of SC components. The pH similarity between PG and viable epidermis limited the detection of PG. NaFl reached the viable epidermis, which was also proved by laser scanning microscopy. Tape stripping and confocal Raman micro-spectroscopy were performed additionally to study NaFl, which revealed penetration depths of ≈5 and ≈8 μm, respectively. Lastly, NR did not permeate the SC. We concluded that the amplitude-weighted mean fluorescence lifetime is the most appropriate FLIM parameter to build up penetration profiles. This work is anticipated to provide a non-invasive TPT-FLIM method for studying the penetration of topically applied drugs and cosmetics into the skin
Follicular Delivery of Caffeine from a Shampoo for Hair Retention
A key factor in the prevention of hair loss is the provision of optimal conditions on the scalp. In this regard, reduction of oxidative stress on the scalp is one critical requirement to support the hair follicles to function optimally. Recently, a novel shampoo formulation technology containing anti-oxidants such as piroctone olamine has been demonstrated to improve hair retention based on micellar degradation and coacervation effects. Caffeine has also been shown to exhibit anti-oxidant activity including the ability to inhibit lipid peroxidation. As with piroctone olamine, it is expected that follicular delivery of caffeine will enhance its anti-oxidant activity in a region that will be beneficial for hair retention. In this study, two shampoo formulations as well as a control formulation were applied to the calf area of n = 9 male participants. The technique of differential tape stripping was applied to obtain the caffeine penetrated to the stratum corneum and to the hair follicles. Isotope-dilution liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was performed to demonstrate caffeine follicular delivery from the shampoo formulas. The results showed that the percentage of caffeine recovered in the hair follicles was 8â9% of the caffeine absorbed into the skin and matched an existing caffeine-based shampoo. In conclusion, a novel shampoo formulation technology has been developed that effectively delivers beneficial anti-oxidants to improve hair retention. This new shampoo is expected to be especially useful in the goal of retaining hair during aging
Microdialysis on Ex Vivo Porcine Ear Skin Can Validly Study Dermal Penetration including the Fraction of Transfollicular PenetrationâDemonstrated on Caffeine Nanocrystals
Common ex vivo methods for penetration investigations often fail to monitor transfollicular penetration appropriately. In the present investigation, the validity of dermal microdialysis on the ex vivo porcine ear skin to investigate penetration kinetics, including transfollicular penetration, was studied. In setup A, a caffeine nanocrystal formulation was compared to a non-particular caffeine gel formulation. In setup B, two caffeine nanocrystal formulations of different sizes (200 nm, 700 nm) were compared to each other. Microdialysis samples were collected for 46 h. After sampling, the skin layers were separated, homogenized, and caffeine was quantified in all samples. In setup A the area under the curve (AUC) after crystal gel formulation application was 12 times higher than after non-particular formulation application. Setup B showed an increased AUC of 42% in the microdialysis data when the 700 nm caffeine crystals were applied compared to the 200 nm crystals. The microdialysis data was supported by the separation, homogenization and extraction data. Microdialysis performed on ex vivo porcine ear skin is a novel experimental setup. It is of high interest for further investigations since it is able to also capture the impact of follicular and transfollicular penetration kinetics as no other ex vivo setup can
Significance of melanin distribution in the epidermis for the protective effect against UV light
Abstract Melanin, the most abundant skin chromophore, is produced by melanocytes and is one of the key components responsible for mediating the skinâs response to ultraviolet radiation (UVR). Because of its antioxidant, radical scavenging, and broadband UV absorbing properties, melanin reduces the penetration of UVR into the nuclei of keratinocytes. Despite its long-established photoprotective role, there is evidence that melanin may also induce oxidative DNA damage in keratinocytes after UV exposure and therefore be involved in the development of melanoma. The present work aimed at evaluating the dependence of UV-induced DNA damage on melanin content and distribution, using reconstructed human epidermis (RHE) models. Tanned and light RHE were irradiated with a 233Â nm UV-C LED source at 60Â mJ/cm2 and a UV lamp at 3Â mJ/cm2. Higher UV-mediated free radicals and DNA damage were detected in tanned RHE with significantly higher melanin content than in light RHE. The melanin distribution in the individual models can explain the lack of photoprotection. Fluorescence lifetime-based analysis and FontanaâMasson staining revealed a non-homogeneous distribution and absence of perinuclear melanin in the tanned RHE compared to the in vivo situation in humans. Extracellularly dispersed epidermal melanin interferes with photoprotection of the keratinocytes
Advanced Skin Antisepsis: Application of UVA-Cleavable Hydroxyethyl Starch Nanocapsules for Improved Eradication of Hair Follicle-Associated Microorganisms
Hair follicles constitute important drug delivery targets for skin antisepsis since they contain â25% of the skin microbiome. Nanoparticles are known to penetrate deeply into hair follicles. By massaging the skin, the follicular penetration process is enhanced based on a ratchet effect. Subsequently, an intrafollicular drug release can be initiated by various trigger mechanisms. Here, we present novel ultraviolet A (UVA)-responsive nanocapsules (NCs) with a size between 400 and 600 nm containing hydroxyethyl starch (HES) functionalized by an o-nitrobenzyl linker. A phase transfer into phosphate-buffered saline (PBS) and ethanol was carried out, during which an aggregation of the particles was observed by means of dynamic light scattering (DLS). The highest stabilization for the target medium ethanol as well as UVA-dependent release of ethanol from the HES-NCs was achieved by adding 0.1% betaine monohydrate. Furthermore, sufficient cytocompatibility of the HES-NCs was demonstrated. On ex vivo porcine ear skin, a strong UVA-induced release of the model drug sulforhodamine 101 (SR101) could be demonstrated after application of the NCs in cyclohexane using laser scanning microscopy. In a final experiment, a microbial reduction comparable to that of an ethanol control was demonstrated on ex vivo porcine ear skin using a novel UVA-LED lamp for triggering the release of ethanol from HES-NCs. Our study provides first indications that an advanced skin antisepsis based on the eradication of intrafollicular microorganisms could be achieved by the topical application of UVA-responsive NCs
Inflammatory Bowel Diseases in Children and Young Adults with Celiac Disease. A Multigroup Matched Comparison
Riociguat treatment in patients with chronic thromboembolic pulmonary hypertension: Final safety data from the EXPERT registry
Objective: The soluble guanylate cyclase stimulator riociguat is approved for the treatment of adult patients with pulmonary arterial hypertension (PAH) and inoperable or persistent/recurrent chronic thromboembolic pulmonary hypertension (CTEPH) following Phase 3 randomized trials. The EXPosurE Registry RiociguaT in patients with pulmonary hypertension (EXPERT) study was designed to monitor the long-term safety of riociguat in clinical practice. Methods: EXPERT was an international, multicenter, prospective, uncontrolled, non-interventional cohort study of patients treated with riociguat. Patients were followed for at least 1 year and up to 4 years from enrollment or until 30 days after stopping riociguat treatment. Primary safety outcomes were adverse events (AEs) and serious adverse events (SAEs) coded using Medical Dictionary for Regulatory Activities preferred terms and System Organ Classes version 21.0, collected during routine clinic visits and collated via case report forms. Results: In total, 956 patients with CTEPH were included in the analysis. The most common AEs in these patients were peripheral edema/edema (11.7%), dizziness (7.5%), right ventricular (RV)/cardiac failure (7.7%), and pneumonia (5.0%). The most common SAEs were RV/cardiac failure (7.4%), pneumonia (4.1%), dyspnea (3.6%), and syncope (2.5%). Exposure-adjusted rates of hemoptysis/pulmonary hemorrhage and hypotension were low and comparable to those in the long-term extension study of riociguat (Chronic Thromboembolic Pulmonary Hypertension Soluble Guanylate Cyclase-Stimulator Trial [CHEST-2]). Conclusion: Data from EXPERT show that in patients with CTEPH, the safety of riociguat in routine practice was consistent with the known safety profile of the drug, and no new safety concerns were identified