Predicting drug penetration across the blood-brain barrier: comparison of micellar liquid chromatography and immobilized artificial membrane liquid chromatography

Several in vitro methods have been investigated for mimicking drug penetration across the blood-brain barrier (BBB) into the central nervous system (CNS). Both micellar liquid chromatography (MLC) and immobilized artificial membrane (IAM) liquid chromatography were tested in this contribution in order to construct models for BBB transfer prediction. MLC measurements were performed on a C18-column with sodium dodecyl sulfate (SDS), polyoxyethylene (23) lauryl ether (Brij35) or sodium deoxycholate (SDC) as surfactants in the micellar mobile phase. IAM liquid chromatography measurements were performed with a Dulbecco’s phosphate-buffered saline (DPBS) and a certain percentage of methanol as organic modifier in the mobile phase. This study aimed to obtain a high correlation between in vivo and predicted log BB values (= concentration of the drug molecule in the brain to concentration in the blood)

Comparison of green enhanced fluidity reversed phase liquid chromatography with HPLC

The growing interest in high throughput assays is the result of the increasing numbers and complexity of samples being produced by modern combinatorial synthetic procedures. The low viscosities and high diffusivities of enhanced fluid mixtures allow highly efficient separations to be achieved with analysis time gain as compared to High-performance liquid chromatography (HPLC). In this study, possibilities and limitations of HPLC mobile phases ethanol/water, acetonitrile/water, and methanol/water at higher proportion aqueous content and acetone/ acetonitrile as non-aqueous mobile phases were evaluated to compare liquid chromatography with green enhanced fluidity liquid chromatography (EFLC) separations by adding different concentrations of carbon dioxide as ternary mobile phase. The techniques were evaluated via van Deemter plots on reversed phase columns. EFLC allows reduce analysis time reduction and to obtain improved column efficiencies by effectively increasing the permeability of the system and by ensuing faster diffusion kinetics and further better selectivity. Similarly the impact on retention and separation in reversed phase using C18 and Naphtylethyl (Pi NAP) stationary phases were explored. A mixture of 16 priority PAH pollutants were used to investigate these effects. Next to interesting changes in selectivity improvements in analysis time and shifting Van Deemter curves could be measured in this way demonstrating the potential of this new green variant of HPLC

The cosmic evolution of dust-corrected metallicity in the neutral gas

Interpreting abundances of Damped Ly-$\alpha$ Absorbers (DLAs) from absorption-line spectroscopy has typically been a challenge because of the presence of dust. Nevertheless, because DLAs trace distant gas-rich galaxies regardless of their luminosity, they provide an attractive way of measuring the evolution of the metallicity of the neutral gas with cosmic time. This has been done extensively so far, but typically not taking proper dust corrections into account. The aims of this paper are to: i) provide a simplified way of calculating dust corrections, based on a single observed [$X$/Fe], ii) assess the importance of dust corrections for DLA metallicities and their evolution, and iii) investigate the cosmic evolution of iron for a large DLA sample. We have derived dust corrections based on the observed [Zn/Fe], [Si/Fe], or [S/Fe], and confirmed their robustness. We present dust-corrected metallicities in a scale of [Fe/H]$_{\rm tot}$ for 236 DLAs over a broad range of $z$, and assess the extent of dust corrections for different metals at different metallicities. Dust corrections in DLAs are important even for Zn (typically of 0.1-0.2, and up to $0.5$~dex), which is often neglected. Finally, we study the evolution of the dust-corrected metallicity with $z$. The DLA metallicities decrease with redshift, by a factor of 50-100 from today to $\sim12.6$ billion years ago ($z=5$). When including dust corrections, the average DLA metallicities are 0.4--0.5~dex higher than without corrections. The upper envelope of the relation between metallicity and $z$ reaches solar metallicity at $z\lesssim0.5$, although some systems can have solar metallicity already out to $z\sim3$.Comment: Forthcoming in A&A. 16 pages, 5 figures, 3 table

Thermoresponsive poly(N-vinylcaprolactam) as stationary phase for aqueous and green liquid chromatography

Poly(N-vinylcaprolactam) (PVCL) connected to aminopropyl silica is a new stationary phase for temperature responsive liquid chromatography (TR-LC). PVCL shows a transition from hydrophilic to hydrophobic interaction between 30 and 40 degrees C. The synthesis is described in detail. The temperature responsive characteristic of the phase is illustrated with a mixture of steroids using pure water as mobile phase. An increase in retention is observed when raising the temperature. H-u plots at different temperatures were constructed. Below the lower critical solution temperature (LCST), no optimal velocity could be measured because of substantial resistance to mass transfer. Above the LCST, u (opt) was ca. 0.3 mm s(-1) with reduced plate heights from 4 at 45 degrees C to 3 at 65 degrees C. The temperature responsive nature of the polymer is lost in green chromatography with ethanol as modifier in concentrations above 5%

Development of Boys and Young Men of Color: Implications of Developmental Science for My Brother's Keeper Initiative

This report describes the My Brother's Keeper Initiative. The report summarizes ideas gleaned from developmental science that may be useful in efforts to reach five of the six initiative's goals: school readiness; third-grade literacy; high school and college graduation; and reduction of violence. The authors discuss features of the initiative designed to promote more positive outcomes and highlight the contributions that developmental science may make to each. Policy recommendations are provided and a discussion about how developmental science may contribute to national dialogue and policy formation