Deep partial thickness burn wounds present big challenges due to the long healing time, large size and irregular shape, pain and reinjury at wound dressing changes, as well as scarring. The clinically effective therapy to alleviate pain at wound dressing changes, and the scar left on the skin after the healing of wound is still unavailable. To combat this, we develop a nanocomposite self-healing hydrogel that can be injected into irregular and deep burn wound beds and subsequently rapidly self-heal to reform into an integrated piece of hydrogel that thoroughly fills the wound area and protects the wound site from external environment, finally being painlessly removed by on-demand dissolving using amino acid solution at wound dressing changes, which accelerates deep partial thickness burn wound healing and prevents scarring. The hydrogel is made out of naturally occurring polymers, namely, water-soluble carboxymethyl chitosan (CMC) and rigid rod-like dialdehyde-modified cellulose nanocrystal (DACNC). They are cross-linked by dynamic Schiff-base linkages between amines from CMC and aldehydes from DACNC. The large aspect ratio and specific surface area of DACNC raise massive active junctions within the hydrogel, which can be readily broken and reformed, allowing hydrogel to rapidly self-heal. Moreover, DACNC serves as nanoreinforcing fillers to improve the hydrogel strength, which also restricts the “soft” CMC chains’ motion when soaked in aqueous system, endowing high fluid uptake capacity (350%) to hydrogel while maintaining integrity. Cytotoxicity assay and three-dimensional cell culture demonstrate excellent biocompatibility of the hydrogel and capacity as extracellular matrix to support cell growth. This work opens a novel pathway to fabricate on-demand dissolvable self-healing hydrogels to speed deep partial thickness burn wound healing and eliminate pain at wound dressing changes and prevent scar formation.

The cerebral cortex must have access to an eye position signal, as humans can report passive changes in eye position in total darkness, and visual responses in many cortical areas are modulated by eye position. The source of this signal is unknown. Here we demonstrate a representation of eye position in monkey primary somatosensory cortex, in the representation of the trigeminal nerve, near cells with a tactile representation of the contralateral brow. The neurons have eye position signals that increase monotonically with increasing orbital eccentricity from near the center of gaze, with directionally selectivity tuned in a Gaussian manner. All directions of eye position are represented in a single hemisphere. The signal is proprioceptive, because it can be obliterated by anesthetizing the contralateral orbit. It is not related to foveal or peripheral visual stimulation, and it represents the position of the eye in the head and not the angle of gaze in space.

Metabolic endotoxemia originating from dysbiotic gut microbiota has been identified as a primary mediator for triggering the chronic low-grade inflammation (CLGI) responsible for the development of obesity. Capsaicin (CAP) is the major pungent bioactivator in chili peppers and has potent anti-obesity functions, yet the mechanisms linking this effect to gut microbiota remain obscure. Here we show that mice fed a high-fat diet (HFD) supplemented with CAP exhibit lower levels of metabolic endotoxemia and CLGI associated with lower body weight gain. High-resolution responses of the microbiota were examined by 16S rRNA sequencing, short-chain fatty acid (SCFA) measurements, and phylogenetic reconstruction of unobserved states (PICRUSt) analysis. The results showed, among others, that dietary CAP induced increased levels of butyrate-producing Ruminococcaceae and Lachnospiraceae, while it caused lower levels of members of the lipopolysaccharide (LPS)-producing family S24_7. Predicted function analysis (PICRUSt) showed depletion of genes involved in bacterial LPS synthesis in response to CAP. We further identified that inhibition of cannabinoid receptor type 1 (CB1) by CAP also contributes to prevention of HFD-induced gut barrier dysfunction. Importantly, fecal microbiota transplantation experiments conducted in germfree mice demonstrated that dietary CAP-induced protection against HFD-induced obesity is transferrable. Moreover, microbiota depletion by a cocktail of antibiotics was sufficient to block the CAP-induced protective phenotype against obesity, further suggesting the role of microbiota in this context. Together, our findings uncover an interaction between dietary CAP and gut microbiota as a novel mechanism for the anti-obesity effect of CAP acting through prevention of microbial dysbiosis, gut barrier dysfunction, and chronic low-grade inflammation.

Purpose: Recently, novel CdTe photon counting x-ray detectors ͑PCXDs͒ with energy discrimination capabilities have been developed. When such detectors are operated under a high x-ray flux, however, coincident pulses distort the recorded energy spectrum. These distortions are called pulse pileup effects. It is essential to compensate for these effects on the recorded energy spectrum in order to take full advantage of spectral information PCXDs provide. Such compensation can be achieved by incorporating a pileup model into the image reconstruction process for computed tomography, that is, as a part of the forward imaging process, and iteratively estimating either the imaged object or the line integrals using, e.g., a maximum likelihood approach. The aim of this study was to develop a new analytical pulse pileup model for both peak and tail pileup effects for nonparalyzable detectors. Methods: The model takes into account the following factors: The bipolar shape of the pulse, the distribution function of time intervals between random events, and the input probability density function of photon energies. The authors used Monte Carlo simulations to evaluate the model. Results: The recorded spectra estimated by the model were in an excellent agreement with those obtained by Monte Carlo simulations for various levels of pulse pileup effects. The coefficients of variation ͑i.e., the root mean square difference divided by the mean of measurements͒ were 5.3%-10.0% for deadtime losses of 1%-50% with a polychromatic incident x-ray spectrum. Conclusions:The proposed pulse pileup model can predict recorded spectrum with relatively good accuracy.

Purpose:Recently, photon counting x-ray detectors ͑PCXDs͒ with energy discrimination capabilities have been developed for potential use in clinical computed tomography ͑CT͒ scanners. These PCXDs have great potential to improve the quality of CT images due to the absence of electronic noise and weights applied to the counts and the additional spectral information. With high count rates encountered in clinical CT, however, coincident photons are recorded as one event with a higher or lower energy due to the finite speed of the PCXD. This phenomenon is called a "pulse pileup event" and results in both a loss of counts ͑called "deadtime losses"͒ and distortion of the recorded energy spectrum. Even though the performance of PCXDs is being improved, it is essential to develop algorithmic methods based on accurate models of the properties of detectors to compensate for these effects. To date, only one PCXD ͑model DXMCT-1, DxRay, Inc., Northridge, CA͒ has been used for clinical CT studies. The aim of that study was to evaluate the agreement between data measured by DXMCT-1 and those predicted by analytical models for the energy response, the deadtime losses, and the distorted recorded spectrum caused by pulse pileup effects. Methods: An energy calibration was performed using 99m Tc ͑140 keV͒, 57 Co ͑122 keV͒, and an x-ray beam obtained with four x-ray tube voltages ͑35, 50, 65, and 80 kVp͒. The DXMCT-1 was placed 150 mm from the x-ray focal spot; the count rates and the spectra were recorded at various tube current values from 10 to 500 A for a tube voltage of 80 kVp. Using these measurements, for each pulse height comparator we estimated three parameters describing the photon energy-pulse height curve, the detector deadtime , a coefficient k that relates the x-ray tube current I to an incident count rate a by a = k ϫ I, and the incident spectrum. The mean pulse shape of all comparators was acquired in a separate study and was used in the model to estimate the distorted recorded spectrum. The agreement between data measured by the DXMCT-1 and those predicted by the models was quantified by the coefficient of variation ͑COV͒, i.e., the root mean square difference divided by the mean of the measurement. Results: Photon energy versus pulse height curves calculated with an analytical model and those measured using the DXMCT-1 were in agreement within 0.2% in terms of the COV. The COV between the output count rates measured and those predicted by analytical models was 2.5% for deadtime losses of up to 60%. The COVs between spectra measured and those predicted by the detector model were within 3.7%-7.2% with deadtime losses of 19%-46%. Conclusions: It has been demonstrated that the performance of the DXMCT-1 agreed exceptionally well with the analytical models regarding the energy response, the count rate, and the recorded spectrum with pulse pileup effects. These models will be useful in developing methods to compensate for these effects in PCXD-based clinical CT systems.