How an aglossic speaker produces an alveolar-like percept without a functional tongue tip.

It has been previously observed [McMicken, Salles, Berg, Vento-Wilson, Rogers, Toutios, and Narayanan. (2017). J. Commun. Disorders, Deaf Stud. Hear. Aids 5(2), 1-6] using real-time magnetic resonance imaging that a speaker with severe congenital tongue hypoplasia (aglossia) had developed a compensatory articulatory strategy where she, in the absence of a functional tongue tip, produced a plosive consonant perceptually similar to /d/ using a bilabial constriction. The present paper provides an updated account of this strategy. It is suggested that the previously observed compensatory bilabial closing that occurs during this speaker's /d/ production is consistent with vocal tract shaping resulting from hyoid raising created with mylohyoid action, which may also be involved in typical /d/ production. Simulating this strategy in a dynamic articulatory synthesis experiment leads to the generation of /d/-like formant transitions.

Membrane mediated motor kinetics in microtubule gliding assays.

Motor-based transport mechanisms are critical for a wide range of eukaryotic cell functions, including the transport of vesicle cargos over long distances. Our understanding of the factors that control and regulate motors when bound to a lipid substrate is however incomplete. We used microtubule gliding assays on a lipid bilayer substrate to investigate the role of membrane diffusion in kinesin-1 on/off binding kinetics and thereby transport velocity. Fluorescence imaging experiments demonstrate motor clustering on single microtubules due to membrane diffusion in the absence of ATP, followed by rapid ATP-induced dissociation during gliding. Our experimental data combined with analytical modeling show that the on/off binding kinetics of the motors are impacted by diffusion and, as a consequence, both the effective binding and unbinding rates for motors are much lower than the expected bare rates. Our results suggest that motor diffusion in the membrane can play a significant role in transport by impacting motor kinetics and can therefore function as a regulator of intracellular transport dynamics.

Evaluation of Weight Thresholds for Pediatric Patients to Use Adult Dosage of Therapeutic Monoclonal Antibodies.

With increasing interest in enrolling adolescent patients in adult trials, a question often arises: when can pediatric patients use adult dosages? For currently approved therapeutic monoclonal antibodies (mAbs) with equivalent adult and pediatric indications, body weight thresholds for pediatric patients to receive adult doses vary from 30 to 75 kg. Our objective is to determine if a consistent weight threshold can be recommended for therapeutic mAbs with wide therapeutic windows. Simulations were run to predict exposure using a population pharmacokinetic model describing the typical PK characteristics of a mAb with linear elimination. Simulated steady-state areas under the concentration-time curves (AUCss ) were compared between pediatric and adult populations. Exponent values of 0.50, 0.75, and 1.0 for the allometric relationship of weight on clearance were also evaluated. Following administration of the same fixed adult dosage in pediatric subjects above a given threshold, median AUCss in the pediatric subjects increased with decreasing weight thresholds. Pediatrics with a minimum weight of 40 kg had median AUCss within 20% to 30% above adult median AUCss when the reference adult population had a median weight ≤80 kg. Higher relative pediatric exposures were seen in lower-weight pediatric subjects when the weight exponent on clearance was >0.75. Simulations suggested that a weight threshold of 40 kg could generally be considered for pediatric subjects to receive the adult dosage for therapeutic mAbs with linear pharmacokinetics. Weight threshold selection should be based on considerations of therapeutic index of the drug product, weight distribution of the reference adult population, and magnitude of weight effect on pharmacokinetic parameters.

Size Distributions and Yields of Giant Vesicles Assembled on Cellulose Papers and Cotton Fabric.

Lamellar phospholipid stacks on cellulose paper vesiculate to form cell-like giant unilamellar vesicles (GUVs) in aqueous solutions. The sizes and yields of the GUVs that result and their relationship to the properties of the cellulose fibers are unknown. Here, we report the characteristics of GUVs produced on four different cellulose substrates, three disordered porous media consisting of randomly entangled cellulose fibers (high-purity cellulose filter papers of different effective porosities), and an ordered network of weaved cellulose fibers (cotton fabric). Large numbers of GUVs formed on all four substrates. This result demonstrates for the first time that GUVs form on cotton fabric. Despite differences in the effective porosities and the configuration of the cellulose fibers, all four substrates yielded populations of GUVs with similar distribution of diameters. The distribution of diameters of the GUVs had a single well-defined peak and a right tail. Ninety-eight percent of the GUVs had diameters less than the average diameter of the cellulose fibers (∼20 micrometers). Cotton fabric produced the highest yield of GUVs with the lowest sample-to-sample variation. Moreover, cotton fabric is reusable. Fabric used sequentially produced similar crops of GUVs at each cycle. At the end of the sequence, there was no apparent change in the cellulose fibers. Cellulose fibers thus promote the vesiculation of lamellar phospholipid stacks in aqueous solutions.

Cellulose Abetted Assembly and Temporally Decoupled Loading of Cargo into Vesicles Synthesized from Functionally Diverse Lamellar Phase Forming Amphiphiles.

Self-assembled micrometer-scale vesicles composed of lamellar phase forming amphiphiles are useful as chemical microreactors, as minimal artificial cells, as protocell mimics for studies of the origins of life, and as vehicles for the targeted delivery of drugs. Given their varied uses, discovery of a universal mechanism that is simple, rapid, and that produces vesicles from a large variety of amphiphiles with different chemical and physical properties at high yield is extremely desirable. Here we show that cellulose, in the form of cellulose paper, facilitates the assembly of membranous vesicles 5-20 µm in diameter from scientifically and technologically important amphiphiles of diverse chemical structures and functionality such as fatty acids (fatty acid vesicles), amphiphilic diblock copolymers, and amphiphilic triblock copolymers (polymersomes). Assembly of vesicles occurred within 90 min of placing the amphiphile-coated cellulose paper into aqueous solutions. Varying thermal and chemical conditions, however, are required for the high-yield assembly of vesicles from the different amphiphiles. The vesicles, when attached to cellulose fibers, have membranes that remain unsealed. This topological characteristic of the vesicles grown on paper allowed the scalable separation of the process of growth from the process of loading cargo (temporally decoupled growth and loading). We demonstrate a temporally decoupled process to rapidly produce large quantities of protein-loaded polymersomes on the benchtop by using high temperatures to accelerate the growth of the polymersomes and subsequently milder temperatures during diffusive loading of the protein cargo.

Novel Application of Cellulose Paper As a Platform for the Macromolecular Self-Assembly of Biomimetic Giant Liposomes.

We report a facile and scalable method to fabricate biomimetic giant liposomes by using a cellulose paper-based materials platform. Termed PAPYRUS for Paper-Abetted liPid hYdRation in aqUeous Solutions, the method is general and can produce liposomes in various aqueous media and at elevated temperatures. Encapsulation of macromolecules and production of liposomes with membranes of complex compositions is straightforward. The ease of manipulation of paper makes practical massive parallelization and scale-up of the fabrication of giant liposomes, demonstrating for the first time the surprising usefulness of paper as a platform for macromolecular self-assembly.