Skin and cutaneous melanocytic lesion simulation in biomedical optics with multilayered phantoms.

The complex inner layered structure of skin influences the photon diffusion inside the cutaneous tissues and determines the reflectance spectra formation. Phantoms are very useful tools to understand the biophysical meaning of parameters involved in light propagation through the skin. To simulate the skin reflectance spectrum, we realized a multilayered skin-like phantom and a multilayered skin phantom with a melanoma-like phantom embedded inside. Materials used were Al(2)O(3) particles, melanin of sepia officinalis and a calibrator for haematology systems dispersed in transparent silicon. Components were optically characterized with indirect techniques. Reflectance phantom spectra were compared with average values of in vivo spectra acquired on a sample of 573 voluntary subjects and 132 pigmented lesions. The phantoms' reflectance spectra agreed with those measured in vivo, mimicking the optical behaviour of the human skin. Further, the phantoms were optically stable and easily manageable, and represented a valid resource in spectra formation comprehension, in diagnostic laser applications and simulation model implementation, such as the Monte Carlo code for non-homogeneous media.

A paradoxical acute effect of levodopa in de novo parkinsonian patients: worsening of some bradykinetic components.

Reports of alterations of reaction times (RTs) in Parkinson's disease are often discordant, particularly when the aim of the research is investigation of the relationship between levodopa (LD) administration and RTs. Slowing of simple RT in a group of de novo parkinsonian patients 30-90 min after administration of LD (Madopar 250) was recently reported. This temporary phenomenon was attributed to a sedative effect of LD. Our present study aimed to repeat these investigations using Multiple Delayed Reaction Verbochronometry (MDRV). We conclude that such a slowing is not a temporary phenomenon but may represent the increased time necessary for the subject to adequately perform the reaction tasks.