A large, open source dataset of stroke anatomical brain images and manual lesion segmentations.

Stroke is the leading cause of adult disability worldwide, with up to two-thirds of individuals experiencing long-term disabilities. Large-scale neuroimaging studies have shown promise in identifying robust biomarkers (e.g., measures of brain structure) of long-term stroke recovery following rehabilitation. However, analyzing large rehabilitation-related datasets is problematic due to barriers in accurate stroke lesion segmentation. Manually-traced lesions are currently the gold standard for lesion segmentation on T1-weighted MRIs, but are labor intensive and require anatomical expertise. While algorithms have been developed to automate this process, the results often lack accuracy. Newer algorithms that employ machine-learning techniques are promising, yet these require large training datasets to optimize performance. Here we present ATLAS (Anatomical Tracings of Lesions After Stroke), an open-source dataset of 304 T1-weighted MRIs with manually segmented lesions and metadata. This large, diverse dataset can be used to train and test lesion segmentation algorithms and provides a standardized dataset for comparing the performance of different segmentation methods. We hope ATLAS release 1.1 will be a useful resource to assess and improve the accuracy of current lesion segmentation methods.

In vitro and in vivo percutaneous absorption of retinol from cosmetic formulations: significance of the skin reservoir and prediction of systemic absorption.

The percutaneous absorption of retinol (Vitamin A) from cosmetic formulations was studied to predict systemic absorption and to understand the significance of the skin reservoir in in vitro absorption studies. Viable skin from fuzzy rat or human subjects was assembled in flow-through diffusion cells for in vitro absorption studies. In vivo absorption studies using fuzzy rats were performed in glass metabolism cages for collection of urine, feces, and body content. Retinol (0.3%) formulations (hydroalcoholic gel and oil-in-water emulsion) containing (3)H-retinol were applied and absorption was measured at 24 or 72 h. All percentages reported are % of applied dose. In vitro studies using human skin and the gel and emulsion vehicles found 0.3 and 1.3% retinol, respectively, in receptor fluid at 24 h. Levels of absorption in the receptor fluid increased over 72 h with the gel and emulsion vehicles. Using the gel vehicle, in vitro rat skin studies found 23% in skin and 6% in receptor fluid at 24 h, while 72-h studies found 18% in skin and 13% in receptor fluid. Thus, significant amounts of retinol remained in rat skin at 24 h and decreased over 72 h, with proportional increases in receptor fluid. In vivo rat studies with the gel found 4% systemic absorption of retinol after 24 h and systemic absorption did not increase at 72 h. Retinol remaining in rat skin after in vivo application was 18% and 13% of the applied dermal dose after 24 and 72 h, respectively. Similar observations were made with the oil-in water emulsion vehicle in the rat. Retinol formed a reservoir in rat skin both in vivo and in vitro. Little additional retinol was bioavailable after 24 h. Comparison of these in vitro and in vivo results for absorption through rat skin indicates that the 24-h in vitro receptor fluid value accurately estimated 24-h in vivo systemic absorption. Therefore, the best single estimate of retinol systemic absorption from in vitro human skin studies is the 24-h receptor fluid value. However, the receptor fluid value from the 72-h extended study may be used in a worst-case exposure estimate. In conclusion, in vivo skin absorption studies can be useful in determining whether to include material in the in vitro skin reservoir as absorbable material in estimates of systemic absorption.

Absorption of lawsone through human skin.

Lawsone (2-hydroxy-1,4-naphthoquinone) is the principal color ingredient in henna, a color additive approved with limitations for coloring hair by the Food and Drug Administration (FDA) under 21 CFR 73.2190. In 2002, the scientific committee on cosmetics and non-food products (SCCNFP), now known as the scientific committee for consumer products (SCCP), evaluated the safety of lawsone as a coloring agent in hair dye products of the European Union (EU). The SCCNFP concluded that lawsone was mutagenic and not suitable for use as a hair coloring agent. As a result, studies were conducted to measure the extent of lawsone absorption through human skin. Lawsone skin absorption was determined from two hair coloring products and two shampoo products, all containing henna. [(14)C]-Lawsone (sp. act. 22.9 mCi/mmol) was added to each commercial product and the products were applied to dermatomed, nonviable human skin mounted in flow-through diffusion cells perfused with a physiological buffer (HEPES-buffered Hanks' balanced salt solution, pH 7.4). Products remained on the skin for 5 minutes (shampoos) and 1 hour (hair color paste). For the henna hair paste products, 0.3 and 1.3% of the applied dose was absorbed into the receptor fluid in 24 hours while 2.2 and 4.0% remained in the skin. For both henna shampoo products, 0.3% of the applied dose was absorbed into the receptor fluid at 24 hours while 3.6 and 6.8% remained in the skin. For all products, most of the lawsone applied was washed from the surface of the skin (83-102%) at the end of the exposure period. Extended absorption studies were conducted for 72 hours to determine if skin levels of lawsone in the 24 hour studies might eventually be percutaneously absorbed. These studies determined that the majority of the lawsone remained in the skin with only a small but significant increase (for three out of four products) in receptor fluid values. Therefore, it appears that receptor fluid values would give a good estimate of lawsone absorption for an exposure estimate and that skin levels of lawsone need not be included.