Ethylene Vinyl Alcohol Copolymer Nanofibrous Cation Exchange Chromatographic Membranes with a Gradient Porous Structure for Lysozyme Separation.

Lysozyme, a common antimicrobial agent, is widely used in the food, biopharmaceutical, chemical, and medicine fields. Rapid and effective isolation of lysozymes is an everlasting topic. In this work, ethylene vinyl alcohol (EVOH) copolymer nanofibrous membranes with a gradient porous structure used for lysozyme adsorption were prepared through layer-by-layer nanofiber wet-laying and a cost-efficient ultraviolet (UV)-assisted graft-modification method, where benzophenone was used as an initiator and 2-acrylamide-2-methylpropanesulfonic acid as a modifying monomer. As indicated in the Fourier Transform Infrared (FTIR) and X-ray photoelectric energy spectrometer (XPS) investigation, sulfonic acid groups were introduced on the surface of the modified nanofibrous membrane, which possessed the ability to adsorb lysozyme. Compared with membranes with homogenous porous structures, membranes with a gradient porous structure present higher static (335 mg/g) and dynamic adsorption capacities (216.3 mg/g). Meanwhile, the adsorption capacity remained high after five cycles of the adsorption-desorption process. The results can be attributed to the gradient porous structure rather than the highest porosity and specific surface area. This suggests that the membrane with comprehensive separation performance can be designed from the view of the transmembrane porous structure, which is of significance for the development of next-generation advanced chromatographic membranes.

Evolution of Surgical Management of Pineal Region Tumors in the Pediatric Population: A 17-Year Experience at a Single Institution.

INTRODUCTION: Pineal region tumors have historically been challenging to treat. Advances in surgical techniques have led to significant changes in care and outcomes for these patients, and this is well demonstrated by our single institution's experience over a 17-year-period in which the evolution of diagnosis, treatment, and outcomes of pineal tumors in pediatric patients will be outlined. METHODS: We retrospectively collected data on all pediatric patients with pineal region lesions treated with surgery at Children's National Hospital (CNH) from 2005 to 2021. Variables analyzed included presenting symptoms, presence of hydrocephalus, diagnostic and surgical approach, pathology, and adverse events, among others. IRB approval was obtained (IRB: STUDY00000009), and consent was waived due to minimal risk to patients included. RESULTS: A total of 43 pediatric patients with pineal region tumors were treated during a 17-year period. Most tumors in our series were germinomas (n = 13, 29.5%) followed by pineoblastomas (n = 10, 22.7%). Twenty seven of the 43 patients (62.8%) in our series received a biopsy to establish diagnosis, and 44.4% went on to have surgery for resection. The most common open approach was posterior interhemispheric (PIH, transcallosal) - used for 59.3% of the patients. Gross total resection was achieved in 50%; recurrence occurred in 20.9% and mortality in 11% over a median follow-up of 47 months. Endoscopic third ventriculostomy (ETV) was employed to treat hydrocephalus in 26 of the 38 patients (68.4%) and was significantly more likely to be performed from 2011 to 2021. Most (73%) of the patients who received an ETV also underwent a concurrent endoscopic biopsy. No difference was found in recurrence rate or mortality in patients who underwent resection compared to those who did not, but complications were more frequent with resection. There was disagreement between frozen and final pathology in 18.4% of biopsies. CONCLUSION: This series describes the evolution of surgical approaches and outcomes over a 17-year-period at a single institution. Complication rates were higher with open resection, reinforcing the safety of pursuing endoscopic biopsy as an initial approach. The most significant changes occurred in the preferential use of ETVs over ventriculoperitoneal shunts. Though there has been a significant evolution in our understanding of and treatment for these tumors, in our series, the outcomes for these patients have not significantly changed over that time.

Chronic, Multi-Site Recordings Supported by Two Low-Cost, Stationary Probe Designs Optimized to Capture Either Single Unit or Local Field Potential Activity in Behaving Rats.

Rodent models of cognitive behavior have greatly contributed to our understanding of human neuropsychiatric disorders. However, to elucidate the neurobiological underpinnings of such disorders or impairments, animal models are more useful when paired with methods for measuring brain function in awake, behaving animals. Standard tools used for systems-neuroscience level investigations are not optimized for large-scale and high-throughput behavioral battery testing due to various factors including cost, time, poor longevity, and selective targeting limited to measuring only a few brain regions at a time. Here we describe two different "user-friendly" methods for building extracellular electrophysiological probes that can be used to measure either single units or local field potentials in rats performing cognitive tasks. Both probe designs leverage several readily available, yet affordable, commercial products to facilitate ease of production and offer maximum flexibility in terms of brain-target locations that can be scalable (32-64 channels) based on experimental needs. Our approach allows neural activity to be recorded simultaneously with behavior and compared between micro (single unit) and more macro (local field potentials) levels of brain activity in order to gain a better understanding of how local brain regions and their connected networks support cognitive functions in rats. We believe our novel probe designs make collecting electrophysiology data easier and will begin to fill the gap in knowledge between basic and clinical research.

Electrophysiological Correlates of Rodent Default-Mode Network Suppression Revealed by Large-Scale Local Field Potential Recordings.

The default-mode network (DMN) in humans consists of a set of brain regions that, as measured with functional magnetic resonance imaging (fMRI), show both intrinsic correlations with each other and suppression during externally oriented tasks. Resting-state fMRI studies have previously identified similar patterns of intrinsic correlations in overlapping brain regions in rodents (A29C/posterior cingulate cortex, parietal cortex, and medial temporal lobe structures). However, due to challenges with performing rodent behavior in an MRI machine, it is still unclear whether activity in rodent DMN regions are suppressed during externally oriented visual tasks. Using distributed local field potential measurements in rats, we have discovered that activity in DMN brain regions noted above show task-related suppression during an externally oriented visual task at alpha and low beta-frequencies. Interestingly, this suppression (particularly in posterior cingulate cortex) was linked with improved performance on the task. Using electroencephalography recordings from a similar task in humans, we identified a similar suppression of activity in posterior cingulate cortex at alpha/low beta-frequencies. Thus, we have identified a common electrophysiological marker of DMN suppression in both rodents and humans. This observation paves the way for future studies using rodents to probe circuit-level functioning of DMN function. SIGNIFICANCE: Here we show that alpha/beta frequency oscillations in rats show key features of DMN activity, including intrinsic correlations between DMN brain regions, task-related suppression, and interference with attention/decision-making. We found similar task-related suppression at alpha/low beta-frequencies of DMN activity in humans.