Molecular crowding facilitates bundling of IMPDH polymers and cytoophidium formation.

The cytoophidium is a unique type of membraneless compartment comprising of filamentous protein polymers. Inosine monophosphate dehydrogenase (IMPDH) catalyzes the rate-limiting step of de novo GTP biosynthesis and plays critical roles in active cell metabolism. However, the molecular regulation of cytoophidium formation is poorly understood. Here we show that human IMPDH2 polymers bundle up to form cytoophidium-like aggregates in vitro when macromolecular crowders are present. The self-association of IMPDH polymers is suggested to rely on electrostatic interactions. In cells, the increase of molecular crowding with hyperosmotic medium induces cytoophidia, while the decrease of that by the inhibition of RNA synthesis perturbs cytoophidium assembly. In addition to IMPDH, CTPS and PRPS cytoophidium could be also induced by hyperosmolality, suggesting a universal phenomenon of cytoophidium-forming proteins. Finally, our results indicate that the cytoophidium can prolong the half-life of IMPDH, which is proposed to be one of conserved functions of this subcellular compartment.

Migratory pharyngeal foreign bodies and related complications: Analysis of 20 cases.

PURPOSE: To explore the diagnostic approach and therapeutic method of migratory pharyngeal foreign bodies and related complications, to improve the understanding of such disease and to reduce misdiagnosis and missed diagnosis. MATERIAL AND METHODS: A retrospective study was performed by collecting patients who were treated because of the related complications caused by migratory pharyngeal foreign bodies from 2012 to 2020. RESULTS: A total of 20 patients were admitted to hospital due to the related complications. 14 cases showed cervical mass; 3 cases showed abscess of the mouth floor; 1 cases showed retropharyngeal abscess; 1 cases showed laryngeal granuloma; 1 cases showed mass of tongue. All patients received imaging examination of B-ultrasonography or computed tomography (CT). 19 patients were treated by surgery, and 1 patient was taken conservative treatment. All foreign bodies was successfully removed. As for the type of foreign bodies, there have 15 cases of fishbone, 2 cases of crabshell, 2 cases of shrimp shell, 1 cases of duck bone. CONCLUSIONS: Migrating foreign bodies and related complications are rare in clinic, much attention should be paid to avoid missed diagnosis or misdiagnosis.

A universal biocompatible coating for enhanced lubrication and bacterial inhibition.

Antibacterial coatings that inhibit bacterial adhesion are essential for many implanted medical devices. A variety of antibacterial strategies, such as repelling or killing bacteria, have been developed, but not yet been completely successful. Here, we develop a universal biocompatible coating for enhanced lubrication and bacterial inhibition. The coating is designed based on mussel-inspired surface-attachable dopamine bases and consists of lubricating zwitterionic polymers poly(2-methacryloxyethyl phosphorylcholine) (MPC) and a bacterial membrane destroying anti-bacteria molecule poly(3-hydroxybutyric acid) (PHB). The coating boasts strong adhesion to surfaces of various materials (such as polydimethylsiloxane (PDMS)/ceramic/316L stainless steel (316L SS); it is biocompatible, and cell/platelet/bacteria repelling, significantly inhibiting bacterial growth. We envision that our strategy represents a universal strategy for surface functionalization of a variety of biomedical devices and implants.

A New Antimicrobial Agent: Poly (3-hydroxybutyric acid) Oligomer.

In this work, it is first reported that the poly (3-hydroxybutyric acid) (PHB) oligomer with a few degrees of polymerization possesses effective antibacterial and antifungal properties. Two preparation methods for the PHB oligomer are described, namely, one-step ring-opening polymerization of ß-butyrolactone and extraction from the fermented PHB polymer. An appropriate amount of the synthesized PHB oligomer shows no physiological toxicity to the skin and major organs of mice. Topological application of the synthesized PHB oligomer imparts antimicrobial ability to non-antibacterial fabrics with washing resistance. The synthesized PHB oligomer offers effective sterilization and promotes wound healing in infected nude mice. Most importantly, the PHB oligomer is also reactive to drug-resistant bacteria. These results suggest that the PHB oligomer is not only a great candidate for antimicrobial modification but also a promising one for biomedical applications. Finally, the antimicrobial mechanisms of the PHB oligomer are revealed, and these include disruption of biofilm and the bacterial wall/membrane, leakage of the intracellular content, inhibition of protein activity, and change in the transmembrane potential.

Membrane gas diffusion measurements with MRI.

Gas transport across polymeric membranes is fundamental to many filtering and separation technologies. To elucidate transport mechanisms, and understand the behaviors of membrane materials, accurate measurement of transport properties is required. We report a new magnetic resonance imaging (MRI) methodology to measure membrane gas phase diffusion coefficients. The MRI challenges of low spin density and short gas phase relaxation times, especially for hydrogen gas, have been successfully overcome with a modified one-dimensional, single-point ramped imaging with T(1) enhancement, measurement. We have measured the diffusion coefficients of both hydrogen gas and sulfur-hexafluoride in a model polymeric membrane of potential interest as a gas separator in metal hydride batteries. The experimental apparatus is a modified one-dimensional diaphragm cell which permits measurement of the diffusion coefficient in experimental times of less than 1 min. The H(2) gas diffusion coefficient in the membrane was 0.54 +/- 0.01 mm(2)/s, while that of sulfur-hexafluoride was 0.14 +/- 0.01 mm(2)/s, at ambient conditions.

Magnetic resonance imaging of water content across the Nafion membrane in an operational PEM fuel cell.

Water management is critical to optimize the operation of polymer electrolyte membrane fuel cells. At present, numerical models are employed to guide water management in such fuel cells. Accurate measurements of water content variation in polymer electrolyte membrane fuel cells are required to validate these models and to optimize fuel cell behavior. We report a direct water content measurement across the Nafion membrane in an operational polymer electrolyte membrane fuel cell, employing double half k-space spin echo single point imaging techniques. The MRI measurements with T2 mapping were undertaken with a parallel plate resonator to avoid the effects of RF screening. The parallel plate resonator employs the electrodes inherent to the fuel cell to create a resonant circuit at RF frequencies for MR excitation and detection, while still operating as a conventional fuel cell at DC. Three stages of fuel cell operation were investigated: activation, operation and dehydration. Each profile was acquired in 6 min, with 6 microm nominal resolution and a SNR of better than 15.

Spatial and temporal mapping of water content across Nafion membranes under wetting and drying conditions.

Water transport and water management are fundamental to polymer electrolyte membrane fuel cell operation. Accurate measurements of water content within and across the Nafion layer are required to elucidate water transport behavior and validate existing numerical models. We report here a direct measurement of water content profiles across a Nafion layer under wetting and drying conditions, using a novel magnetic resonance imaging methodology developed for this purpose. This method, multi-echo double half k-space spin echo single point imaging, based on a pure phase encode spin echo, is designed for high resolution 1D depth imaging of thin film samples. The method generates high resolution (<8 microm) depth images with an SNR greater than 20, in an image acquisition time of less than 2 min. The high temporal resolution permits water content measurements in the transient states of wetting and drying, in addition to the steady state.