Risk Factors Associated with Postoperative Obesity in Childhood-Onset Craniopharyngioma Patients: A Case-Control Study.

OBJECTIVE: Identifying risk factors associated with obesity after craniopharyngioma (CP) resection is pivotal for the prediction and prevention of postoperative obesity. Although multiple elegant studies have investigated this issue, studies focusing on Asian pediatric patients are missing. Herein, we retrospectively analyzed the risk factors associated with obesity after childhood-onset CP surgery in our center, aiming to provide insights into approaches reducing the occurrence of postoperative obesity. METHODS: The clinical data of 53 children with CP who met the inclusion criteria from July 2011 to August 2020 in our center were collected for retrospective analysis. Univariate and multivariate logistic retrospective analyses were used to identify independent risk factors contributing to postoperative obesity. A review of the available literature reporting the risk factors associated with obesity after CP surgery over the past two decades was performed for comparison. RESULTS: The median age at diagnosis of this cohort was 11.0 years, with a median follow-up of 44.0 months (range = 8-119 months). Eighteen (34.0%) experienced obesity at the last follow-up. Multivariate logistic regression analysis showed preoperative body mass index standard deviation score (odds ratio [OR], 1.71; 95% confidence interval [CI]: 1.01-2.90; P = 0.046), preoperative hypothalamic involvement (OR, 29.38; 95% CI: 1.76-490.66; P = 0.019), and age at diagnosis (OR, 0.76; 95% CI: 0.61-0.95; P = 0.016) were independent risk factors for obesity after childhood-onset CP resection. CONCLUSIONS: Our results combined with previous literature support preoperative body mass index standard deviation score, preoperative hypothalamic involvement, and age at diagnosis are the independent risk factors associated with obesity after childhood-onset CP resection.

Exploring the pathological relationships between adamantinomatous craniopharyngioma and contiguous structures with tumor origin.

PURPOSE: Identifying relationships between craniopharyngiomas (CPs) and contiguous structures, and tumor origin are crucial for treatments. This study attempted to explore the relationships and tumor origin. METHODS: CPs that underwent endoscopic surgeries were enrolled. The interfacial specimens of CPs attaching the hypothalamus, pituitary stalk (PS), pituitary grand (PG), optic chiasma (OC) and brain tissue (BT) were pathologically examined. Boundaries between CPs and these structures were observed during operations. Expression of ß-catenin and stem cell markers were analyzed to explore the tumor origin. Outcomes of patients were assessed. RESULTS: A total of 34 CPs were categorized into two groups based on the locations of finger-like protrusions (FP). Group A comprised 18 CPs with FP only present in the specimens attaching to hypothalamus. The surface of these CPs was fused with hypothalamus under endoscopic videos. However, the specimens attaching to the PS, PG, OC, and BT showed no FP. Clear boundaries was observed between these CPs and these structures. Group B comprised 16 CPs with FP only present in the specimens attaching to PS. The tumor surface was fused with PS. Specimens attaching to the hypothalamus, PG, OC and BT showed no FP. Clear boundary was observed among these CPs with these structures. These results implied CPs only invaded a certain part of hypothalamic-pituitary axis. ß-catenin and stem cells markers mainly distributed in the FP tissues of both groups. Patients in group B achieved better outcomes than group A. CONCLUSIONS: CPs only invade the hypothalamic-pituitary axis with FP and the FP would be the tumor origin.

In Situ Observation of Current Generation in ZnO Nanowire Based Nanogenerators Using a CAFM Integrated into an SEM.

In this work, we monitor in situ the movement of ZnO piezoelectric nanowires by using a conductive atomic force microscope integrated into a scanning electron microscope. This setup allows seeing the bending of the nanowires and simultaneously measuring the currents generated. We conclude that the currents generated not only come from piezoelectric effect, but also from contact potential and triboelectric effect. These contributions have been ignored in all previous reports in this field, meaning that the power conversion efficiency of these devices may have been systematically overestimated. Our study helps to clarify the working mechanism of piezoelectric nanogenerators based on ZnO nanowires.

Dielectric Breakdown in Chemical Vapor Deposited Hexagonal Boron Nitride.

Insulating films are essential in multiple electronic devices because they can provide essential functionalities, such as capacitance effects and electrical fields. Two-dimensional (2D) layered materials have superb electronic, physical, chemical, thermal, and optical properties, and they can be effectively used to provide additional performances, such as flexibility and transparency. 2D layered insulators are called to be essential in future electronic devices, but their reliability, degradation kinetics, and dielectric breakdown (BD) process are still not understood. In this work, the dielectric breakdown process of multilayer hexagonal boron nitride (h-BN) is analyzed on the nanoscale and on the device level, and the experimental results are studied via theoretical models. It is found that under electrical stress, local charge accumulation and charge trapping/detrapping are the onset mechanisms for dielectric BD formation. By means of conductive atomic force microscopy, the BD event was triggered at several locations on the surface of different dielectrics (SiO2, HfO2, Al2O3, multilayer h-BN, and monolayer h-BN); BD-induced hillocks rapidly appeared on the surface of all of them when the BD was reached, except in monolayer h-BN. The high thermal conductivity of h-BN combined with the one-atom-thick nature are genuine factors contributing to heat dissipation at the BD spot, which avoids self-accelerated and thermally driven catastrophic BD. These results point to monolayer h-BN as a sublime dielectric in terms of reliability, which may have important implications in future digital electronic devices.

Note: Fabrication of a fast-response and user-friendly environmental chamber for atomic force microscopes.

The atomic force microscope is one of the most widespread tools in science, but many suppliers do not provide a competitive solution to make experiments in controlled atmospheres. Here, we provide a solution to this problem by fabricating a fast-response and user-friendly environmental chamber. We corroborate the correct functioning of the chamber by studying the formation of local anodic oxidation on a silicon sample (biased under opposite polarities), an effect that can be suppressed by measuring in a dry nitrogen atmosphere. The usefulness of this chamber goes beyond the example here presented, and it could be used in many other fields of science, including physics, mechanics, microelectronics, nanotechnology, medicine, and biology.