The Evaluation of Meloxicam Nanocrystals by Oral Administration with Different Particle Sizes

Meloxicam (MLX) is a non-steroidal anti-inflammatory drug used to treat rheumatoid arthritis and osteoarthritis. However, its poor water solubility limits the dissolution process and influences absorption. In order to solve this problem and improve its bioavailability, we prepared it in nanocrystals with three different particle sizes to improve solubility and compare the differences between various particle sizes. The nanocrystal particle sizes were studied through dynamic light scattering (DLS) and laser scattering (LS). Transmission electron microscopy (TEM) was used to characterize the morphology of nanocrystals. The sizes of meloxicam-nanocrystals-A (MLX-NCs-A), meloxicam-nanocrystals-B (MLX-NCs-B), and meloxicam-nanocrystals-C (MLX-NCs-C) were 3.262 ± 0.016 μm, 460.2 ± 9.5 nm, and 204.9 ± 2.8 nm, respectively. Molecular simulation was used to explore the distribution and interaction energy of MLX molecules and stabilizer molecules in water. The results of differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD) proved that the crystalline state did not change in the preparation process. Transport studies of the Caco-2 cell model indicated that the cumulative degree of transport would increase as the particle size decreased. Additionally, plasma concentration–time curves showed that the AUC0–∞ of MLX-NCs-C were 3.58- and 2.92-fold greater than those of MLX-NCs-A and MLX-NCs-B, respectively. These results indicate that preparing MLX in nanocrystals can effectively improve the bioavailability, and the particle size of nanocrystals is an important factor in transmission and absorption.

Virtual reality as a new tool for transport data collection

Transport studies that adopt complex analyses present methodological challenges that lead to the use of innovative techniques to address the limitations of traditional methods. In the Latin American context, people consider security as a relevant variable in their daily lives. Thus, when people travel around the city and choose a mode of transport, secu-rity becomes an important factor and should therefore be included in transport studies. However, the definition of security in terms of transport in the Colombian context remains unclear. Therefore, we examined the security percep-tion effect on transport mode choice by addressing security as a latent variable consisting of three elements: environ-ment, subject and transport mode. We proposed the use of virtual reality (VR) to recreate travel routes and offer partic-ipants a scenario of choice closer to the natural conditions of a trip. The participants were provided routes in the form of immersive 3D videos recreating natural trip conditions to identify their choices and travel behaviour. Recordings were made of daily scenarios and existing urban environments portraying real and active modes of transport, giving respondents an almost-natural experience. The use of 360-degree immersive videos offers a multisensory experience allowing both the capture of socioeconomic and travel information and the collection of journey perception. The experiment evaluated two environments in Medellín, Colombia (secure (E1) and insecure (E2)) and studied the effects of lighting conditions (day (D) and night (N)). A total of four videos (E1D, E1N, E2D and E2N) depicting six transport modes in tandem were assessed by 92 participants from Medellín and Bogotá, Colombia. We found that environment-associated security perception varies depending on the time of the journey (day/night) and one’s familiarity with the environment. The research results position VR as a tool that offers high potential to support transport studies. We found that people’s movements, gestures and expressions while participating in the VR experiments resembled what was expected from journeys in reality. VR constitutes a relevant tool for transport studies, as it allows for an assessment of active transport mode perceptions. It prevents participants from being exposed to the risk associated with travel to specific places and carries out several routes in different transport modes even when participants cannot or have never undertaken journeys in the modes under assessment.

Overview of Drug Transporters in Human Placenta

The transport of drugs across the placenta is a point of great importance in pharmacotherapy during pregnancy. However, the knowledge of drug transport in pregnancy is mostly based on experimental clinical data, and the underlying biological mechanisms are not fully understood. In this review, we summarize the current knowledge of drug transporters in the human placenta. We only refer to human data since the placenta demonstrates great diversity among species. In addition, we describe the experimental models that have been used in human placental transport studies and discuss their availability. A better understanding of placental drug transporters will be beneficial for the health of pregnant women who need drug treatment and their fetuses.

Influence of Device Geometry on Transport Properties of Topological Insulator Microflakes

In the transport studies of topological insulators, microflakes exfoliated from bulk single crystals are often used because of the convenience in sample preparation and the accessibility to high carrier mobilities. Here, based on finite element analysis, we show that for the non-Hall-bar shaped topological insulator samples, the measured four-point resistances can be substantially modified by the sample geometry, bulk and surface resistivities, and magnetic field. Geometry correction factors must be introduced for accurately converting the four-point resistances to the longitudinal resistivity and Hall resistivity. The magnetic field dependence of inhomogeneous current density distribution can lead to pronounced positive magnetoresistance and nonlinear Hall effect that would not exist in the samples of ideal Hall bar geometry.

Intraluminal Behavior of Various Transporter Substrates in the Rat Gastrointestinal Tract

Purpose: The aim of this study was to evaluate the intraluminal behavior of various transporter substrates in different regions of the gastrointestinal (GI) tract. Methods: Drug solutions containing non-absorbable FITC-dextran 4000 (FD-4), were orally administered to rats. Residual water was sampled from the GI regions to measure the luminal drug concentration. Results: Cephalexin (CEX), a substrate of the proton-coupled oligopeptide transporter, was absorbed rapidly, and no drug was detected in the lower small intestine. Saquinavir (SQV) was primarily absorbed in the upper region. However, unlike CEX, SQV was detected even in the lower segment probably due to the efflux of SQV via P-glycoprotein (P-gp). The concentration of methotrexate (MTX) showed a similar pattern to that of non-absorbable FD-4. The low absorption of MTX was probably due to efflux via several efflux transporters, and the limited expression of proton-coupled folate transporter, an absorptive transporter for MTX, in the upper region. Conclusion: This study revealed that the luminal concentration pattern of each drug differed considerably depending on the site because of the different absorption properties and luminal volumes. Although further investigation using a specific transporter inhibitor or transporter-knockout animals are necessary to clarify the actual contribution of each transporter to the drug absorption, this information will be valuable in evaluating transporter-mediated drug absorption in in vitro transport studies for ensuring optimal drug concentrations.

Impurity transport studies at the HSX stellarator using active and passive CVI spectroscopy

The transport of carbon impurities has been studied in the helically symmetric stellarator experiment (HSX) using active and passive charge exchange recombination spectroscopy (CHERS). For the analysis of the CHERS signals, the STRAHL impurity transport code has been re-written in the python programming language and optimized for the application in stellarators. In addition, neutral densities both along the NBI line of sight as well as for the background plasma have been calculated using the FIDASIM code. By using the basinhopping algorithm to minimize the difference between experimental and predicted active and passive signals, significant levels of impurity diffusion are observed. Comparisons with neoclassical calculations from DKES/PENTA show that the inferred levels exceed the neoclassical transport by about a factor of four in the core and more than 100 times towards the plasma edge, thus indicating a high level of anomalous transport. This observation is in agreement with experimental heat diffusivites determined from a power balance analysis which exhibit strong anomalous transport as well.