Micropore Closure Rates following Microneedle Application at Various Anatomical Sites in Healthy Human Subjects

<b><i>Introduction:</i></b> The continuous availability of open micropores is crucial for a successful microneedle (MN) drug delivery strategy. However, micropore lifetime depends on intrinsic skin functional and anatomical characteristics, which vary significantly at different anatomical sites. <b><i>Objective:</i></b> This pilot study explored if differences exist in micropore closure timeframes at 3 anatomical sites – upper arm, volar forearm, and abdomen. <b><i>Methods:</i></b> Healthy subjects (<i>n</i> = 35) self-identifying as Asian (<i>n</i> = 9), Bi-/multiracial (<i>n</i> = 2), Black (<i>n</i> = 9), Latino (<i>n</i> = 6), and White (<i>n</i> = 9) completed the study. The upper arm, volar forearm, and abdomen were treated with MNs; skin impedance and transepidermal water loss (TEWL) were measured at baseline and post-MN to confirm micropore formation. Impedance was measured for 3 days to evaluate micropore lifetime. Measurements of L*, which quantifies the skin lightness/darkness, were made using a tristimulus colorimeter. Micropore lifetime was determined by comparing baseline and post-MN impedance measurements, and micropore closure half-life was predicted using mathematical modeling. <b><i>Results:</i></b> Post-MN increase in TEWL and decrease in impedance were significant (<i>p</i> &#x3c; 0.05), confirming successful micropore formation at all anatomical sites. When data were analyzed according to subject self-identified racial/ethnic groups, the mean micropore closure time at the abdomen (63.09 ± 13.13 h) was longer than the upper arm (60.34 ± 14.69 h) and volar forearm (58.29 ± 16.76 h). The predicted micropore closure half-life at anatomical sites was the abdomen (25.86 ± 14.96 h) ≈ upper arm (23.69 ± 13.67 h) &#x3e; volar forearm (20.2 ± 11.99 h). Differences were not statistically significant between groups. Objective categorization by L* showed that the darker skin may be associated with longer micropore closure time at the abdomen site. <b><i>Conclusions:</i></b> Our results suggest that anatomical site of application may not be a source of significant variability in micropore closure time. These findings may help reduce the number of physiological parameters that need to be explicitly considered when developing drug products to support MN-assisted drug delivery strategies.

Atypical Signs of Compartment Syndrome Caused by Pressure Injury in Forearm

Acute compartment syndrome (ACS) is a serious complication which is usually associated with fractures. Herein, we report a case of a patient with volar forearm compartment syndrome associated with closed muscle rupture without fracture of which the only external signs were superficial contact burns and pain. A 21-year-old man presented to our emergency department with painful swelling in the right forearm after being caught in a machine. Although he presented with pain, no open wound or fracture was seen. The patient was presumed to have a contusion and discharged. He presented with worsening pain the next day, when typical clinical features of ACS were observed and emergency fasciotomy was performed. Intraoperatively, ruptured flexor muscles were noted. Delayed presentation of forearm compartment syndrome accompanied by closed muscle rupture without fracture is extremely rare. Diagnosis is not easy because severe pain could be the only clue and can mask the signs of compartment syndrome, at risk of being missed.

Effects of Exercise on the Skin Epithelial Barrier of Young Elite Athletes-Swimming Comparatively to Non-Water Sports Training Session

The benefits of swimming have been extensively assessed. However, swimming pools contain chlorine and other irritating chemicals that may induce contact dermatitis. To evaluate the effect of a swimming training session on transepidermal water loss (TWEL) in swimmers compared to football players, elite swimmers and football players were invited to participate (58 athletes) in the study, where TEWL was measured before, immediately after, and 30 min after a 2 h training session. The probe was held on the dorsum of the hand, volar forearm, and on the antecubital flexure for 1 min. The volar forearm, antecubital flexure, and hand dorsum showed a significant increase in TEWL in swimmers in both measurements after training compared to baseline (p < 0.001). In football players, an increase in TEWL was observed on the hands’ dorsum between baseline and after training measurements. The variations on TEWL levels before and immediately after the training session were higher among swimmers on the volar forearm (p = 0.002) and antecubital flexure (p = 0.019). Our findings support the effect of the training environment—swimming pool versus outdoor sports—on the skin barrier function, with an increase of transepidermal water loss immediately after exercise. Exposure to a swimming pool environment in a 2 h training session may lead to changes in skin barrier function.

Epimysial Transposition Flap: A Novel Technique for Coverage of Exposed Tendon after Tissue Transfer

Background The radial forearm flap (RFF) is a versatile flap that can be used for soft-tissue coverage or as a source of vascularized bone during reconstruction. A problem that can arise after RFF harvest is tendon exposure in the donor site, which may lead to tendon injury and restriction of the hand and wrist’s range of motion. Many different methods for providing adequate tendon coverage in the donor site after RFF harvest have been reported. We present a novel technique for coverage of exposed tendon in the volar forearm with an epimysial transposition flap and a split-thickness skin graft (STSG). Methods Retrospective review of two cases: one salvage case with exposed tendon after harvesting an RFF and another with exposed volar forearm tendon after traumatic injuries. Variables of interest were post-operative STSG integration and hand/wrist range of motion. Results Both cases demonstrated 100% graft take at 5-week follow-up. No decrease in hand/wrist range of motion in the patient that could undergo testing. Conclusion We introduce two cases for coverage of exposed flexor tendon in the volar forearm with an epimysial transposition flap. This can be used as a salvage operation for coverage of exposed tendon or as an acute method of tendon coverage prior to skin grafting. In both cases, the skin graft had excellent incorporation.

Study of the Human Stickiness Perception of Wet Fabric on the Volar Forearm via Two Contact Modes: Friction and Adhesion-Separation

Wet fabric clinging to human skin may cause stickiness perception and facilitate wearing discomfort. This study aims to investigate the stickiness perception of wet fabrics via two contact modes (friction and adhesion-separation) as well as the influences of fabric properties and contact features on stickiness perception. A set of dynamic contact devices was developed to drive the samples to move horizontally or vertically on volar forearms. According to the magnitude estimation approach, 12 subjects were asked to assess the stickiness perceptions caused by 64 types of contact stimuli. The results showed that the water absorption capacity had a significant and negative correlation with stickiness perception under the two contact modes. However, the surface roughness was neither related to stickiness perception under the friction mode nor to stickiness perception under the adhesion-separation mode. There was an interaction between contact pressure and sliding velocity. The sliding velocity at medium or high pressure had a significant effect on stickiness perception, but the separating velocity had no significant effect. Stickiness perception under the friction mode is higher than that under the adhesion-separation mode in most cases. Consequently, the friction mode was considered the main contact mode that evokes stickiness perception.

Retinol Has a Skin Dehydrating Effect That Can Be Improved by a Mixture of Water-Soluble Polysaccharides

It is common that retinoids used in skincare can cause skin dryness, irritation and redness which is a complaint for the use of these molecules in skincare formulations. Objective: to investigate the influence of a mixture of polysaccharides to improve retinol-based formulations in a 12-day inner volar forearm study. Methods: in total, 22 inner volar forearms were treated over a 12-day topical application of a Placebo formulation containing 0.5% retinol verses a formulation containing 0.5% retinol and 3.0% of a complex of polysaccharides. Application occurred 2X/day in the morning and evening. Skin testing included barrier disruption, erythema, and skin hydration. After a 3-day regression of treatment, skin hydration was measured again. Results: the 0.5% retinol Placebo formulation showed a significant impact on skin dehydration compared to untreated control or polysaccharide-treated areas. The formulation containing retinol and 3.0% of the polysaccharides, maintained skin hydration levels comparable to the untreated control. Neither formulation had a statistically significant impact on skin erythema or barrier disruption. After the 3-day regression, the polysaccharide mixture continued to demonstrate significant moisturization benefits superior to the untreated and active-treated sites. Conclusions: a mixture of polysaccharides was able to mitigate the short-term skin drying effects of retinol and continued to moisturize the skin after a 3-Day regression.

543 Acute Carpal Tunnel Syndrome from a Solar Panel Electrical Injury: A Case Report and Literature Review

Introduction The utilization of solar panels for residential and industrial purposes is increasing. Electrical injury from solar panels has not been well defined. Most of the literature on electrical burns is predominately from alternating current (AC) injuries instead of direct current (DC) as seen in solar panels. The implication of solar panel electrical injury in the pathogenesis of acute carpal tunnel syndrome has yet to be reported. Methods A retrospective chart review of a patient presenting to our burn unit following a solar panel electrical injury was performed. Results The patient was a 46 year old otherwise healthy male who presented after 5–10 seconds of high voltage (~7500V) direct current injury to his right forearm. The patient had deep partial thickness burns to his right hypothenar eminence and a full thickness defect with exposed muscle on his right volar forearm. On admission he had complete function, but within hours developed an inability to move his hand. He was taken for exploration on hospital day 2 because of mildly elevated compartment pressures, pain, and paresthesia. The hypothenar injury was noted to have converted to full thickness injury and a distal right volar forearm fasciotomy and carpal tunnel release was performed. On hospital day 3, the patient’s pain and neurologic examination improved. At 3 month follow-up, the patient had some restored function of his hand, but reduced grip strength, and mild persistent pain and paresthesia in the volar wrist and hand. Conclusions Solar panel injuries are expected to rise. The use of high voltage direct current energy has the potential to cause serious harm and appropriate awareness can lead to thorough management and better outcomes of burn victims. With electrical injuries to the hand, providers should have a low threshold for carpal tunnel syndrome, whose symptoms may be complicated by concomitant compartment syndrome of the hand and/or forearm. Lastly, as with most burn injuries a multidisciplinary approach should be established with focus on long term care. Applicability of Research to Practice We suspect that this new etiology of electrical burn is on the rise as we see more solar panels being utilized. Physician should be familiar with potential complications in this complex patient population.