Polycyclic aromatic hydrocarbon skin permeation efficiency in vitro is lower through human than pigskin and decreases with lipophilicity.

Polycyclic aromatic hydrocarbons (PAH) are persistent environmental pollutants, which occasionally appear as contaminants in consumer products. Upon dermal contact, transfer of PAH into the stratum corneum (s.c.) and migration through the skin may occur, resulting in this class of highly toxic compounds to become bioavailable. In this study, dermal penetration through human and porcine skin of 24 PAH, comprising broad molar mass (M: 152-302 g/mol) and octanol-water partition coefficient (logP: 3.9-7.3) ranges, was evaluated via Franz diffusion cell in vitro assays. More lipophilic and potentially more toxic PAH had decreased permeation rates through the rather lipophilic s.c. into the more hydrophilic viable (epi-)dermis. Furthermore, human skin was less permeable than pigskin, a commonly used surrogate in skin penetration studies. In particular, the s.c. of human skin retains a greater share of PAH, an effect that is more pronounced for smaller PAH. Additionally, we compared the skin permeation kinetics of different PAH in pigskin. While small PAH (M < 230 g/mol, logP < 6) permeate the skin quickly and are detected in the receptor fluid after 2 h, large PAH (M > 252 g/mol, logP ≥ 6) do not fully permeate the skin up to 48 h. This indicates that highly lipophilic PAH do not become bioavailable as readily as their smaller congeners when transferred to the skin surface. Our data suggest that pigskin could be used as a surrogate for worst case scenario estimates of dermal PAH permeation through human skin.

Use of the FallAkte Plus System as an IT Infrastructure for the North Rhine-Westphalian General Practice Research Network: Mixed Methods Usability Study.

BACKGROUND: Primary care research networks can generate important information in the setting where most patients are seen and treated. However, this requires a suitable IT infrastructure (ITI), which the North Rhine-Westphalian general practice research network is looking to implement. OBJECTIVE: This mixed methods research study aims to evaluate (study 1) requirements for an ITI and (study 2) the usability of an IT solution already available on the market, the FallAkte Plus (FA+) system for the North Rhine-Westphalian general practice research network, which comprises 8 primary care university institutes in Germany's largest state. METHODS: In study 1, a survey was conducted among researchers from the institutes to identify the requirements for a suitable ITI. The questionnaire consisted of standardized questions with open-ended responses. In study 2, a mixed method approach combining a think-aloud approach and a quantitative survey was used to evaluate the usability and acceptance of the FA+ system among 3 user groups: researchers, general practitioners, and practice assistants. Respondents were asked to assess the usability with the validated system usability scale and to test a short questionnaire on vaccination management through FA+. RESULTS: In study 1, five of 8 institutes participated in the requirements survey. A total of 32 user requirements related primarily to study management were identified, including data entry, data storage, and user access management. In study 2, a total of 36 participants (24 researchers and 12 general practitioners or practice assistants) were surveyed in the mixed methods study of an already existing IT solution. The tutorial video and handouts explaining how to use the FA+ system were well received. Researchers, unlike practice personnel, were concerned about data security and data protection regarding the system's emergency feature, which enables access to all patient data. The median overall system usability scale rating was 60 (IQR 33.0-85.0), whereby practice personnel (median 82, IQR 58.0-94.0) assigned higher ratings than researchers (median 44, IQR 14.0-61.5). Users appreciated the option to integrate data from practices and other health care facilities. However, they voted against the use of the FA+ system due to a lack of support for various study formats. CONCLUSIONS: Usability assessments vary markedly by professional group and role. In its current stage of development, the FA+ system does not fully meet the requirements for a suitable ITI. Improvements in the user interface, performance, interoperability, security, and advanced features are necessary to make it more effective and user-friendly. Collaborating with end users and incorporating their feedback are crucial for the successful development of any practice network research ITI.

Less efficient skin penetration of the metal allergen Pd2+ compared to Ni2+ and Co2+ from patch test preparations.

BACKGROUND: Contrary to Ni2+- and Co2+-induced allergic contact dermatitis (ACD), reactions against Pd2+ are rare. However, Pd2+ activates a larger T cell fraction in vitro, suggesting an inefficient skin penetration. OBJECTIVES: This study compares Ni2+, Co2+ and Pd2+ skin penetration from commonly used diagnostic patch test preparations (PTPs) and aqueous metal salt solutions. METHODS: Using Franz diffusion cell assays, we applied the metals in PTPs (5% NiSO4, 1% CoCl2, 2% PdCl2 and 3% Na2PdCl4) and in solution to pigskin for 48 h, thereby mirroring the time frame of a patch test. The different compartments were analysed individually by inductively coupled plasma mass spectrometry. RESULTS: Metal ions were mainly retained in the upper stratum corneum layers. After application of PTPs, concentrations in the viable skin were lower for Pd2+ (1 and 7 µM) compared to Ni2+ and Co2+ (54 and 17 µM). CONCLUSIONS: Ni2+ and Co2+ penetrated the skin more efficiently than Pd2+ and thus may sensitize and elicit ACD more easily. This was observed for ions applied in petrolatum and aqueous solutions. We hypothesize that the differently charged metal complexes are responsible for the varying skin penetration behaviours.

Migration of polycyclic aromatic hydrocarbons from a polymer surrogate through the stratum corneum layer of the skin.

In this study, we determined partition (Ksc/m) and diffusion (Dsc) coefficients of five different polycyclic aromatic hydrocarbons (PAH) migrating from squalane into and through the stratum corneum (s.c.) layer of the skin. Carcinogenic PAH have previously been detected in numerous polymer-based consumer products, especially those dyed with carbon black. Upon dermal contact with these products, PAH may penetrate into and through the viable layers of the skin by passing the s.c. and thus may become bioavailable. Squalane, a frequent ingredient in cosmetics, has also been used as a polymer surrogate matrix in previous studies. Ksc/m and Dsc are relevant parameters for risk assessment because they allow estimating the potential of a substance to become bioavailable upon dermal exposure. We developed an analytical method involving incubation of pigskin with naphthalene, anthracene, pyrene, benzo[a]pyrene and dibenzo[a,h]pyrene in Franz diffusion cell assays under quasi-infinite dose conditions. PAH were subsequently quantified within individual s.c. layers by gas chromatography coupled to tandem mass spectrometry. The resulting PAH depth profiles in the s.c. were fitted to a solution of Fick's second law of diffusion, yielding Ksc/m and Dsc. The decadic logarithm logKsc/m ranged from -0.43 to +0.69 and showed a trend to higher values for PAH with higher molecular masses. Dsc, on the other hand, was similar for the four higher molecular mass PAH but about 4.6-fold lower than for naphthalene. Moreover, our data suggests that the s.c./viable epidermis boundary layer represents the most relevant barrier for the skin penetration of higher molecular mass PAH. Finally, we empirically derived a mathematical description of the concentration depth profiles that better fits our data. We correlated the resulting parameters to substance specific constants such as the logarithmic octanol-water partition coefficient logP, Ksc/m and the removal rate at the s.c./viable epidermis boundary layer.

Continuous removal of single cell layers by tape stripping the stratum corneum - a histological study.

Studies on the penetration of toxicologically or pharmaceutically relevant substances through the skin and, more specifically, through the stratum corneum (s.c.) often rely on the well-established method of tape stripping. Tape stripping involves the removal of skin layers by means of adhesive tape, which is usually followed by quantification of dermally applied substances in these layers. However, the amount of s.c. removed by each individual tape strip is still a matter of scientific debate. While some studies imply that the amount of s.c. adhering to each tape strip decreases with increasing depth into the s.c., others observed a constant removal rate. All these studies rely on the quantification of the amount of s.c. captured on individual or pooled tape strips. Here, we present an approach whereby we measured the amount of s.c. remaining on excised porcine skin in the process of tape stripping. Staining and bloating of the s.c. allowed to measure its thickness and to count individual s.c. layers, respectively. Histologically, we show that the s.c. remaining on the skin decreased linearly as a function of strips taken. We found that each tape strip removes about 0.4 µm of s.c., which corresponds to approximately one cellular layer. With a high coefficient of determination (r2 > 0.95), we were able to linearly correlate the thickness of the remaining s.c., the number of remaining cell layers and the number of tape strips applied. Furthermore, we elaborate on possible reasons for the discrepancies reported in the scientific literature regarding the amount of s.c. removed by each tape strip.

Ion mobility and gas phase H/D exchange: revealing the importance of a single hydrogen bond for the chiral recognition of crown ether ammonium complexes.

Two new BINOL-based chiral crown ether/ammonium complexes are studied by travelling-wave ion-mobility spectrometry. Homo- and heterochiral crown ether/ammonium complexes differ in their collision cross sections, and these differences go along with changes in hydrogen bonding as revealed by gas phase H/D-exchange experiments. Applications for the determination of enantiomeric excess are discussed.