Urticaria Multiforme: An Uncommon Hypersensitivity Rash in Children.

The differential diagnosis of rashes in children is challenging. Pediatric rashes indicate a broad spectrum of clinical conditions and include those that are benign and self-limiting to those that may indicate a serious multisystem inflammatory response. It is essential that emergency nurse practitioners have the knowledge and skill set to accurately identify the spectrum of rashes in the pediatric population to arrive at the correct diagnosis for patient management and avoid costly and unnecessary diagnostic testing. The purpose of this article is to describe a case report of a young child with urticaria multiforme, a commonly misdiagnosed clinical condition, including the distinctive clinical features, differential diagnosis, and most current treatment recommendations. Other clinical conditions that present with skin lesions resembling urticaria multiforme conditions have also been discussed.

Electropneumotactile Stimulation: Multimodal Haptic Actuators Enabled by a Stretchable Conductive Polymer on Inflatable Pockets.

This paper describes a type of haptic device that delivers two modes of stimulation simultaneously and at the same locations on the skin. The two modes of stimulation are mechanical (delivered pneumatically by inflatable air pockets embedded within a silicone elastomer) and electrical (delivered by a conductive polymer). The key enabling aspect of this work is the use of a highly plasticized conductive polymer based on poly(3,4-ethylenedioxythiphene) (PEDOT) blended with elastomeric polyurethane (PU). To fabricate the "electropneumotactile" device, the polymeric electrodes are overlaid directly on top of the elastomeric pneumatic actuator pockets. Co-placement of the pneumatic actuators and the electrotactile electrodes is enabled by the stretchability of the PEDOT:OTs/PU blend, allowing the electrotactiles to conform to underlying pneumatic pockets under deformation. The blend of PEDOT and PU has a Young's modulus of ~150 MPa with little degradation in conductivity following repeated inflation of the air pockets. The ability to perceive simultaneous delivery of two sensations to the same location on the skin are supported by experiments using human subjects. These results show that participants can successfully detect the location of pneumatic stimulation and whether electrotactile stimulation is delivered (yes/no) at a rate significantly above chance (mean accuracy = 94%).

Virtual Texture Generated using Elastomeric Conductive Block Copolymer in Wireless Multimodal Haptic Glove.

Haptic devices are in general more adept at mimicking the bulk properties of materials than they are at mimicking the surface properties. This paper describes a haptic glove capable of producing sensations reminiscent of three types of near-surface properties: hardness, temperature, and roughness. To accomplish this mixed mode of stimulation, three types of haptic actuators were combined: vibrotactile motors, thermoelectric devices, and electrotactile electrodes made from a stretchable conductive polymer synthesized in our laboratory. This polymer consisted of a stretchable polyanion which served as a scaffold for the polymerization of poly(3,4-ethylenedioxythiophene) (PEDOT). The scaffold was synthesized using controlled radical polymerization to afford material of low dispersity, relatively high conductivity (0.1 S cm-1), and low impedance relative to metals. The glove was equipped with flex sensors to make it possible to control a robotic hand and a hand in virtual reality (VR). In psychophysical experiments, human participants were able to discern combinations of electrotactile, vibrotactile, and thermal stimulation in VR. Participants trained to associate these sensations with roughness, hardness, and temperature had an overall accuracy of 98%, while untrained participants had an accuracy of 85%. Sensations could similarly be conveyed using a robotic hand equipped with sensors for pressure and temperature.

Organic Haptics: Intersection of Materials Chemistry and Tactile Perception.

The goal of the field of haptics is to create technologies that manipulate the sense of touch. In virtual and augmented reality, haptic devices are for touch what loudspeakers and RGB displays are for hearing and vision. Haptic systems that utilize micromotors or other miniaturized mechanical devices (e.g., for vibration and pneumatic actuation) produce interesting effects, but are quite far from reproducing the feeling of real materials. They are especially deficient in recapitulating surface properties: fine texture, friction, viscoelasticity, tack, and softness. The central argument of this Progress Report is that to reproduce the feel of everyday objects requires chemistry: molecular control over the properties of materials and ultimately design of materials which can change these properties in real time. Stimuli-responsive organic materials, such as polymers and composites, are a class of materials which can change their oxidation state, conductivity, shape, and rheological properties, and thus might be useful in future haptic technologies. Moreover, the use of such materials in research on tactile perception could help elucidate the limits of human tactile sensitivity. The work described represents the beginnings of this new area of inquiry, in which the defining approach is the marriage of materials science and psychology.

Healable Thermoplastic for Kinesthetic Feedback in Wearable Haptic Devices.

The word "haptics" refers to technologies designed to stimulate the tactile and kinesthetic senses. Kinesthesia-the sense of motion-is triggered by imposing forces upon the joints, tendons, and muscles to recreate the geometry and stiffness of objects, as may be useful in physical therapy or virtual reality. Here, we introduce a form of kinesthetic feedback by manipulating the mechanical properties of spandex impregnated with a thermoplastic polymer. Heating or cooling this textile-thermoplastic composite just above or below its glass transition temperature (T g) dramatically changes its mechanical properties (corresponding to a decrease in storage modulus from 36 MPa to 0.55 MPa). In the form of a glove, the composite can also be healed after inadvertent overextension in its stiffened state by heating it above its T g. When fitted with thermoelectric devices for active heating and cooling, the flexible or stiffened state of a glove can be perceived by human subjects. As an example of a human-machine interface, the glove is used to control a robotic finger. When the robotic finger makes contact with a wall, a signal is sent to thermoelectric devices in the glove to cool (stiffen the finger) and thus provide kinesthetic feedback to the user.

Role of indentation depth and contact area on human perception of softness for haptic interfaces.

In engineering, the "softness" of an object, as measured by an indenter, manifests as two measurable parameters: (i) indentation depth and (ii) contact area. For humans, softness is not well defined, although it is believed that perception depends on the same two parameters. Decoupling their relative contributions, however, has not been straightforward because most bulk-"off-the-shelf"-materials exhibit the same ratio between the indentation depth and contact area. Here, we decoupled indentation depth and contact area by fabricating elastomeric slabs with precise thicknesses and microstructured surfaces. Human subject experiments using two-alternative forced-choice and magnitude estimation tests showed that the indentation depth and contact area contributed independently to perceived softness. We found an explicit relationship between the perceived softness of an object and its geometric properties. Using this approach, it is possible to design objects for human interaction with a desired level of perceived softness.

Ionotactile Stimulation: Nonvolatile Ionic Gels for Human-Machine Interfaces.

We report the application of a nonvolatile ionic gel as a soft, conductive interface for electrotactile stimulation. Materials characterization reveals that, compared to a conventional ionic hydrogel, a glycerol-containing ionic gel does not dry out in air, has better adhesion to skin, and exhibits a similar impedance spectrum in the range of physiological frequencies. Moreover, psychophysical experiments reveal that the nonvolatile gel also exhibits a wider window of comfortable electrotactile stimulation. Finally, a simple pixelated device is fabricated to demonstrate spatial resolution of the haptic signal.

Measurement of Cohesion and Adhesion of Semiconducting Polymers by Scratch Testing: Effect of Side-Chain Length and Degree of Polymerization.

Most advantages of organic electronic materials are enabled by mechanical deformability, as flexible (and stretchable) devices made from these materials must be able to withstand roll-to-roll printing and survive mechanical insults from the external environment. Cohesion and adhesion are two properties that dictate the mechanical reliability of a flexible organic electronic device. In this paper, progressive-load scratch tests are used for the first time to correlate the cohesive and adhesive behavior of poly(3-alkylthiophenes) (P3ATs) with respect to two molecular parameters: length of the alkyl side chain and molecular weight. In contrast to metrological techniques based on buckling or pull testing of pseudofreestanding films, scratch tests reveal information about both the cohesive and adhesive properties of thin polymeric films from a single procedure. Our data show a decrease in cohesion and adhesion, that is, a decrease in overall mechanical robustness, with increasing length of the side chain. This behavior is likely due to increases in free volume and concomitant decreases in the glass transition temperature. In contrast, we observe increases in both the cohesion and adhesion with increasing molecular weight. This behavior is attributed to an increased density of entanglements with high molecular weight, which manifests as increased extensibility. These observations are consistent with the results of molecular dynamics simulations. Interestingly, the normal (applied) forces associated with cohesive and adhesive failure are directly proportional to the average degree of polymerization, as opposed to simply the molecular weight, as the length of the alkyl side chain increases the molecular weight without increasing the degree of polymerization.

Nanoparticle biointerfacing by platelet membrane cloaking.

Development of functional nanoparticles can be encumbered by unanticipated material properties and biological events, which can affect nanoparticle effectiveness in complex, physiologically relevant systems. Despite the advances in bottom-up nanoengineering and surface chemistry, reductionist functionalization approaches remain inadequate in replicating the complex interfaces present in nature and cannot avoid exposure of foreign materials. Here we report on the preparation of polymeric nanoparticles enclosed in the plasma membrane of human platelets, which are a unique population of cellular fragments that adhere to a variety of disease-relevant substrates. The resulting nanoparticles possess a right-side-out unilamellar membrane coating functionalized with immunomodulatory and adhesion antigens associated with platelets. Compared to uncoated particles, the platelet membrane-cloaked nanoparticles have reduced cellular uptake by macrophage-like cells and lack particle-induced complement activation in autologous human plasma. The cloaked nanoparticles also display platelet-mimicking properties such as selective adhesion to damaged human and rodent vasculatures as well as enhanced binding to platelet-adhering pathogens. In an experimental rat model of coronary restenosis and a mouse model of systemic bacterial infection, docetaxel and vancomycin, respectively, show enhanced therapeutic efficacy when delivered by the platelet-mimetic nanoparticles. The multifaceted biointerfacing enabled by the platelet membrane cloaking method provides a new approach in developing functional nanoparticles for disease-targeted delivery.

Interfacial interactions between natural RBC membranes and synthetic polymeric nanoparticles.

The unique structural features and stealth properties of a recently developed red blood cell membrane-cloaked nanoparticle (RBC-NP) platform raise curiosity over the interfacial interactions between natural cellular membranes and polymeric nanoparticle substrates. Herein, several interfacial aspects of the RBC-NPs are examined, including completeness of membrane coverage, membrane sidedness upon coating, and the effects of polymeric particles' surface charge and surface curvature on the membrane cloaking process. The study shows that RBC membranes completely cover negatively charged polymeric nanoparticles in a right-side-out manner and enhance the particles' colloidal stability. The membrane cloaking process is applicable to particle substrates with a diameter ranging from 65 to 340 nm. Additionally, the study reveals that both surface glycans on RBC membranes and the substrate properties play a significant role in driving and directing the membrane-particle assembly. These findings further the understanding of the dynamics between cellular membranes and nanoscale substrates and provide valuable information toward future development and characterization of cellular membrane-cloaked nanodevices.

Lipid-insertion enables targeting functionalization of erythrocyte membrane-cloaked nanoparticles.

RBC membrane-cloaked polymeric nanoparticles represent an emerging nanocarrier platform with extended circulation in vivo. A lipid-insertion method is employed to functionalize these nanoparticles without the need for direct chemical conjugation. Insertion of both folate and the nucleolin-targeting aptamer AS1411 shows receptor-specific targeting against model cancer cell lines.

'Marker-of-self' functionalization of nanoscale particles through a top-down cellular membrane coating approach.

We investigate the 'marker-of-self' functionalization of nanoparticles through coating of natural RBC membranes. The membrane translocation approach is shown to be highly efficient and bestows nanoparticles with correctly oriented and functional immunomodulatory proteins such as CD47 at equivalent density to natural RBCs.

Erythrocyte membrane-cloaked polymeric nanoparticles for controlled drug loading and release.

AIM: Polymeric nanoparticles (NPs) cloaked by red blood cell membrane (RBCm) confer the combined advantage of both long circulation lifetime and controlled drug release. The authors carried out studies to gain a better understanding of the drug loading, drug-release kinetics and cell-based efficacy of RBCm-cloaked NPs. MATERIALS & METHODS: Two strategies for loading doxorubicin into the RBCm-cloaked NPs were compared: physical encapsulation and chemical conjugation. In vitro efficacy was examined using the acute myeloid leukemia cell line, Kasumi-1. RESULTS: It was found that the chemical conjugation strategy resulted in a more sustained drug release profile, and that the RBCm cloak provided a barrier, retarding the outward diffusion of encapsulated drug molecules. It was also demonstrated that RBCm-cloaked NPs exhibit higher toxicity in comparison with free doxorubicin. CONCLUSION: These results indicate that the RBCm-cloaked NPs hold great promise to become a valuable drug-delivery platform for the treatment of various diseases such as blood cancers.

Alignment of cricoid cartilage and esophagus and its potential influence on the effectiveness of Sellick maneuver in children.

OBJECTIVE: The effectiveness of cricoid pressure in preventing aspiration of gastric contents during rapid sequence intubation may be limited if the esophagus is laterally displaced from the trachea at the level of the cricoid cartilage. Esophageal lateral displacement has been reported to occur in 50% to 90% of adults. Children 8 years and older assume the anatomic airway characteristics of adults, and therefore, we hypothesized that esophageal displacement would be significantly more common in older versus younger children. The purposes of this study were to determine the alignment of the trachea to the esophagus at the level of the cricoid cartilage on cervical spine or neck computed tomographic (CT) scans and to compare the frequency and quantity of esophageal displacement between children younger than 8 years and children 8 years and older. METHODS: This is a retrospective cross-sectional study of children (aged 0-17 years) who had cervical spine/neck CT scans performed at a 110-bed urban children's hospital. Two pediatric radiologists blinded to the patients' clinical symptoms and signs and final diagnosis independently determined the alignment of the airway at the level of the cricoid cartilage with the esophagus from cervical spine/neck CT scans. Lateral displacement of the esophagus from the airway was determined by measuring the distance from the ipsilateral outer wall edges of the esophagus and trachea. RESULTS: There were 172 cervical spine/neck CT scans reviewed. Of 87 children younger than 8 years, 27 were excluded, and of 85 children 8 to 17 years, 25 were excluded. The remaining 120 patients were eligible for the study, 60 patients were younger than 8 years and 60 patients were aged 8 to 17 years. For children younger than 8 years, their mean age was 3.58 years. There were 34 (57%) males. The most common indication for CT scan of the cervical spine/neck was motor vehicle crash 26 (46%). For children aged 8 to 17 years, their mean age was 13.3 years. There were 30 (50%) males. The most common indication for CT scan of the cervical spine/neck was motor vehicle crash 34 (57%). Alignment of the airway with the esophagus showed esophageal displacement in 36 (30%) of the patients with displacement in 27 (45%) of the younger children compared with 9 (15%) of the older children. The rate of displacement was significantly greater in the younger children (difference in rates was 30% and 95% confidence interval was 14%-46%). All displacements were to the left. The mean distance of esophageal displacement was significantly greater in the older children (2.42 vs 1.81 mm). The difference in the means was 0.61 mm, and the 95% confidence interval was 1.2 to 0.02 mm. CONCLUSIONS: This is the first pediatric study on the rate and degree of esophageal displacement from the airway at the level of the cricoid cartilage. Lateral displacement of the esophagus occurred at a significantly greater rate in the younger (45%) compared with the older (15%) children, which was directly opposite of our hypothesis. Of the 36 children (30%) with esophageal displacement, all had displacement to the left of the cricoid cartilage.

Communicating bronchopulmonary foregut malformation: a case report.

CBPFM is a rare finding associated with GERD in infancy. To our knowledge this case represents the twenty-fifth reported case in a child and the one-hundred and thirty first reported case in the literature overall. This case serves to remind the practitioner that children with symptoms of GER may not be just one of the endless number of happy spitters.