A mathematical evaluation of dose-dependent PpIX fluorescence kinetics in vivo

Sonophoresis enhances the skin penetration of 5-aminolevulinic acid: A promising pretreatment for photodynamic therapy

5-aminolevulinic acid (5-ALA) has a poor penetrance of the skin with topical application, which reduces the efficacy of photodynamic therapy (PDT). Sonophoresis involves the use of sound waves or ultrasonic energy to enhance the topical or transdermal delivery of drugs. The purpose of this study was to investigate the effects of sonophoresis on the penetration of 5-ALA into the skin. We calculated in vitro transdermal accumulation of ALA, and the fluorescence images were collected for analysis. The cumulative amount of 5-ALA that penetrated the skin with sonophoresis increased over time and was significantly larger than that without sonophoresis (p < 0.01). With 5% 5-ALA and sonophoresis, the distinct localization of 5-ALA-PpIX in sebaceous glands started to appear 30 min after 5-ALA application, which is much earlier than with 5% 5-ALA only. For all incubation times, fluorescence intensities distributing in sebaceous glands were significantly higher in sonophoresis treated than non-sonophoresis treated skin (p < 0.05). Sonophoresis could be a technique of choice for enhancing the production of 5-ALA-induced PpIX and improving the efficacy of 5-ALA-based PDT, which may decrease the treatment time, lower the cost of therapy and enhance the clinical improvement, allowing many more patients to be treated.

3D finite compartment modeling of formation and healing of bruises may identify methods for age determination of bruises

Simulating the spatial and temporal behavior of bruises may identify methods that allow accurate age determination of bruises to assess child abuse. We developed a numerical 3D model to simulate the spatial kinetics of hemoglobin and bilirubin during the formation and healing of bruises. Using this model, we studied how skin thickness, bruise diameter and diffusivities affect the formation and healing of circular symmetric bruises and compared a simulated bruise with a natural inhomogeneous bruise. Healing is faster for smaller bruises in thinner and less dense skin. The simulated and natural bruises showed similar spatial and temporal dynamics. The different spatio-temporal dynamics of hemoglobin and bilirubin allows age determination of model bruises. Combining our model predictions with individual natural bruises may allow optimizing our model parameters. It may particularly identify methods for more accurate age determination than currently possible to aid the assessment of child abuse.