Mechano-Regulation Of Meniscus Development And Maturation

The meniscus is an integral load bearing fibrous tissue of the knee joint that derives its mechanical function from the unique geometry and precise organization and composition of its extracellular matrix (ECM). While the importance of the highly specialized ECM is well appreciated in the mature meniscus, how this structural complexity is achieved during development remains poorly understood, and in particular, what interplay exists between the cells that build the matrix and their rapidly evolving microenvironment is unclear. To address these knowledge gaps, we begin by establishing a detailed timeline of the concurrent spatiotemporal changes that occur at both the cellular and matrix level during murine meniscus maturation, through use of Col1-YFP, Col2-CFP, Col10-mCherry fluorescent reporter mice, as well as histological analysis, and region specific high-throughput qPCR. We report that distinct cellular and matrix features defining specific meniscus tissue zones are present at birth, and that regional specialization continues during postnatal growth and maturation, possibly due to onset of load bearing use. Importantly, we define a framework for investigating the reciprocal feedback between cells and their evolving microenvironment—thus laying the foundation for future mechanistic work. Informed by the finding that key structural features of the meniscus matrix are established at birth, the remainder of this thesis addresses how this nascent organization is established. By analyzing key timepoints in knee joint development, we show that the genesis of ordered meniscus matrix is downstream of early cellular patterning characterized by marked fibrillation of the actin cytoskeleton. This suggests that cells and subcellular structures act as a physical template that directs alignment of the deposited fibrous matrix. Through the use of muscular dysgenesis (mdg) and splotch-delayed (Spd) mouse mutants that lack skeletal muscle contraction and joint motion, we further show that this critical cellular re-arrangement prior to meniscus formation does not fully occur without muscle contraction and leads to tissue dissociation—demonstrating that extrinsic forces play an instructive role in the tissue’s formation. Finally, we probe the impact of embryonic cell-mediated physical cues (adhesion, cytoskeletal arrangement) on subsequent meniscus assembly by generating targeted deletion of non-muscle myosin isoforms NM-IIA and NM-IIB (Myh dKO) in meniscus precursor cells during knee development. We demonstrate that cells of Myh dKO animals have defective cellular connectivity and so assemble a disorganized fibrillar matrix at birth, but these deficiencies in matrix alignment are somewhat corrected with postnatal maturation. Together, this work establishes that both cell-generated and extrinsic physical cues are imperative in the establishment of the initial meniscus structure that is built upon and further refined during postnatal growth

Prediction of Bioequivalence and Food Effect Using Flux- and Solubility-Based Methods

In this work, two different approaches have been developed to predict the food effect and the bioequivalence of marketed itraconazole (ITRA) formulations. Kinetic solubility and simultaneous dissolution–permeation tests of three (ITRA) formulations (Sporanox capsules and solution and SUBA-ITRA capsules) were carried out in simulated fasted and fed states. Fraction of dose absorbed ratios estimating food effect and bioequivalence were calculated based on these results and were compared to the in vivo study results published by Medicines Agencies. The comparison demonstrated that kinetic solubility and flux values could be used as input parameters for biopharmaceutics modeling and simulations to estimate food effect and bioequivalence. Both prediction methods were able to determine a slightly negative food effect in the case of the Sporanox solution and also a pronounced positive food effect for the Sporanox capsule. Superior bioavailability was predicted when the Sporanox solution was compared to the Sporanox capsule (in agreement with in vivo data)

Kinetochore genes are coordinately up-regulated in human tumors as part of a FoxM1-related cell division program

The key player in directing proper chromosome segregation is the macromolecular kinetochore complex, which mediates DNA–microtubule interactions. Previous studies testing individual kinetochore genes documented examples of their overexpression in tumors relative to normal tissue, leading to proposals that up-regulation of specific kinetochore genes may promote tumor progression. However, kinetochore components do not function in isolation, and previous studies did not comprehensively compare the expression behavior of kinetochore components. Here we analyze the expression behavior of the full range of human kinetochore components in diverse published expression compendia, including normal tissues and tumor samples. Our results demonstrate that kinetochore genes are rarely overexpressed individually. Instead, we find that core kinetochore genes are coordinately regulated with other cell division genes under virtually all conditions. This expression pattern is strongly correlated with the expression of the forkhead transcription factor FoxM1, which binds to the majority of cell division promoters. These observations suggest that kinetochore gene up-regulation in cancer reflects a general activation of the cell division program and that altered expression of individual kinetochore genes is unlikely to play a causal role in tumorigenesis.Leukemia & Lymphoma Society of America (Scholar Award)National Institute of General Medical Sciences (U.S.) (Grant GM088313)American Cancer Society (Research Scholar Grant 121776)National Science Foundation (U.S.). Graduate Research Fellowshi

A Formal Language to Convey Linguistic Information. A Study in Practical Logic

The author discusses problems of treating formal languages to present linguistic data in machine translation systems or linguistic interfaces for man-computer communication.L'auteur discute de problèmes relatifs à la création de langages formels pour représenter les données linguistiques dans des systèmes de traduction automatique ou dans des interfaces linguistiques pour la communication homme-machine

Investigation and mathematical description of the real driving force of passive transport of drug molecules from supersaturated solutions

The aim of this study was to investigate the impact of formulation excipients and solubilizing additives on dissolution, supersaturation, and membrane transport of an active pharmaceutical ingredient (API). When a poorly water-soluble API is formulated to enhance its dissolution, additives, such as surfactants, polymers, and cyclodextrins, have an effect not only on dissolution profile but also on the measured physicochemical properties (solubility, pKa, permeability) of the drug while the excipient is present, therefore also affecting the driving force of membrane transport. Meloxicam, a nonsteroidal anti-inflammatory drug, was chosen as a poorly water-soluble model drug and formulated in order to enhance its dissolution using solvent-based electrospinning. Three polyvinylpyrrolidone (PVP) derivatives (K30, K90, and VA 64), Soluplus, and (2-hydroxypropyl)-β-cyclodextrin were used to create five different amorphous solid dispersions of meloxicam. Through experimental design, the various formulation additives that could influence the characteristics of dissolution and permeation through artificial membrane were observed by carrying out a simultaneous dissolution-permeation study with a side-by-side diffusion cell, μFLUX. Although the dissolution profiles of the formulations were found to be very similar, in the case of Soluplus containing formulation the flux was superior, showing that the driving force of membrane transport cannot be simplified to the concentration gradient. Supersaturation gradient, the difference in degree of supersaturation (defined as the ratio of dissolved amount of the drug to its thermodynamic solubility) between the donor and acceptor side, was found to be the driving force of membrane transport. It was mathematically derived from Fick's first law, and experimentally proved to be universal on several meloxicam containing ASDs and DMSO stock solution. © 2016 American Chemical Society