Molecular Mechanisms of AMPA Receptor Trafficking in the Nervous System.

Synaptic plasticity enhances or reduces connections between neurons, affecting learning and memory. Postsynaptic AMPARs mediate greater than 90% of the rapid excitatory synaptic transmission in glutamatergic neurons. The number and subunit composition of AMPARs are fundamental to synaptic plasticity and the formation of entire neural networks. Accordingly, the insertion and functionalization of AMPARs at the postsynaptic membrane have become a core issue related to neural circuit formation and information processing in the central nervous system. In this review, we summarize current knowledge regarding the related mechanisms of AMPAR expression and trafficking. The proteins related to AMPAR trafficking are discussed in detail, including vesicle-related proteins, cytoskeletal proteins, synaptic proteins, and protein kinases. Furthermore, significant emphasis was placed on the pivotal role of the actin cytoskeleton, which spans throughout the entire transport process in AMPAR transport, indicating that the actin cytoskeleton may serve as a fundamental basis for AMPAR trafficking. Additionally, we summarize the proteases involved in AMPAR post-translational modifications. Moreover, we provide an overview of AMPAR transport and localization to the postsynaptic membrane. Understanding the assembly, trafficking, and dynamic synaptic expression mechanisms of AMPAR may provide valuable insights into the cognitive decline associated with neurodegenerative diseases.

Mucosal loss as a critical factor in esophageal stricture formation after mucosal resection: a pilot experiment in a porcine model.

BACKGROUND AND AIM: Esophageal stricture is a major complication of large areas endoscopic submucosal dissection (ESD). Until now, the critical mechanism of esophageal stricture remains unclear. We examined the role of mucosal loss versus submucosal damage in esophageal stricture formation after mucosal resection using a porcine model. MATERIALS AND METHODS: Twelve swine were randomly divided into two groups, each of 6. In each group, two 5-cm-long submucosal tunnels were made to involve 1/3rd of the widths of the anterior and posterior esophageal circumference. The entire mucosal roofs of both tunnels were resected in group A. In group B, the tunnel roof mucosa was incised longitudinally along the length of the tunnel, but without excision of any mucosa. Stricture formation was evaluated by endoscopy after 1, 2, and 4 weeks, respectively. Anatomical and histological examinations were performed after euthanasia. RESULTS: Healing observed on endoscopy in both groups after 1 week. Group A (mucosa resected) developed mild-to-severe esophageal stricture, dysphagia, and weight loss. In contrast, no esophageal stricture was evident in group B (mucosa incisions without resection) after 2 and 4 weeks, respectively. Macroscopic examination showed severe esophageal stricture and shortening of esophagus in only group A. Inflammation and fibrous hyperplasia of the submucosal layer was observed on histological examination in both groups. CONCLUSION: The extent of loss of esophageal mucosa appears to be a critical factor for esophageal stricture. Inflammation followed by fibrosis may contribute to alteration in compliance of the esophagus but is not the main mechanism of postresection stricture.

Transparent thermoplastic polyurethane air filters for efficient electrostatic capture of particulate matter pollutants.

Particulate matter (PM) air pollution has been established as a significant threat to public health and a destructive factor to the climate and eco-systems. In order to eliminate the effects of PM air pollution, various air filtering strategies based on electrospun nanofibers have recently been developed. However, to date, almost none of the existing nanofibers based air filters can meet the requirements of high-performance air PM filtering, including high PM removal efficiency, low resistance to airflow, and long service life, etc. For the first time, we report a fabrication process using the electrospinning method for air filters based on thermoplastic polyurethane (TPU) nanofibers. The average diameters of TPU nanofibers are tunable from 0.14 ± 0.06 µm to 0.82 ± 0.22 µm by changing the TPU concentrations in polymeric solutions. The optimized TPU nanofibers based air filters demonstrate the attractive attributes of high PM2.5 removal efficiency up to 98.92%, good optical transparency of ∼60%, low pressure drop of ∼10 Pa, high quality factor of 0.45 Pa-1, and long service life under the flow rate of 200 ml min-1, which is ground-breaking compared with the existing nanofibers based air filters. These TPU nanofibers based air filters, with the excellent filtration performance and light transmittance, will shed light on the future research of nanofibers for various filtration applications and greatly benefit the public health by reducing the effects of PM air pollution.

[Study on interaction between heme-iron of myoglobin and metal ions by visible spectroscopy (I)].

Myoglobin (Mb) made up of a multipeptides train and a heme prosthetic group is a kind of protein taking charge of O2 stock and distribution in mammal cells, especially in muscle cells. The heme-iron plays a key role in O2 transfer and transport. In the present paper, the direct interaction between heme-iron of myoglobin and additional metal ions [Cu (II), Zn (II) and Co( II)] was studied by UV-Vis spectra. It was found that heme-iron of myoglobin directly interacted with additional Cu(II), Zn(II) and Co(II), these metal ions could drag iron ion out from heme prosthetic group of myoglobin, and subsequently myoglobin became myoglobin derivatives lacking iron ion. At the same time, the effect of the additional metal ions concentration on the direction interaction was studied. It was shown that the direct interaction increased gradually with the amount of external metal ions added. When the ratio of Mb and metal ions is 1 : 10, the interaction intension between the three metal ions and Mb is Co(II), Zn(II) and Cu(II) in turn. For the first time, the authors confirmed that the direct interaction has occurred between heme-iron of myoglobin and additional metal ions, and saw about how the metal ions intension affects the direct interaction.