Hidradenitis Suppurativa.

Hidradenitis suppurativa (HS) is a chronic disease characterized by recurrent painful abscesses and chronic sinus tracts in intertriginous areas. In the United States, HS disproportionally affects adults of African-American heritage. Depending on the severity of disease, the consequences of HS can be far-reaching, significantly affecting mental health and quality of life. In recent years, concerted research efforts have been made to better understand the pathophysiology of the disease as well as identify emerging new treatment targets. Herein, we discuss the clinical presentation, diagnostic criteria, and treatment approach of HS with a focus on skin of color.

Hyaluronic acid, HAS1, and HAS2 are significantly upregulated during muscle hypertrophy.

Hyaluronic acid (HA) is a component of the extracellular matrix (ECM) in most vertebrate tissues and is thought to play a significant role during development, wound healing, and regeneration. In vitro studies have shown that HA enhances muscle progenitor cell recruitment and inhibits premature myotube fusion, implicating a role for this glycosaminoglycan in functional repair. However, the spatiotemporal distribution of HA during muscle growth and repair was unknown. We hypothesized that inducing hypertrophy via synergist ablation would increase the expression of HA and the HA synthases (HAS1-HAS3). We found that HA and HAS1-HAS3 were significantly upregulated within the plantaris muscle in response to Achilles tenectomy. HA concentration significantly increased 2.8-fold after 2 days but decreased towards levels comparable to age-matched controls by 14 days. Using immunohistochemistry, we found the colocalization of HAS1-HAS3 with macrophages, blood vessel epithelia, and fibroblasts varied in response to time and/or tenectomy. At the level of gene expression, only HAS1 and HAS2 significantly increased with respect to both time and tenectomy. The profiles of additional genes that influence ECM composition during muscle repair, tenascin-C, type I collagen, the HA-degrading hyaluronidases (Hyal) and matrix metalloproteinases (MMP) were also investigated. Hyal1 and Hyal2 were highly expressed in skeletal muscle but did not change after tenectomy; however, indicators of hypertrophy, MMP-2 and MMP-14, were significantly upregulated from 2 to 14 days. These results indicate that HA levels dynamically change in response to a hypertrophic stimulus and various cells may participate in this mechanism of skeletal muscle adaptation.

Benzalkonium Chloride: An Irritant and Sensitizer.

BACKGROUND: Benzalkonium chloride (BAK) is a known irritant, and potentially cross-reacting quaternary ammonium compounds are commonly used as preservatives in personal care products. OBJECTIVE: The aim of the study was to review positive reactions to BAK in 615 patients patch tested for suspected allergic contact dermatitis. METHODS: A retrospective chart review was performed in 615 patients patch tested from June 2015 to October 2016. All patients were tested to a Modified American Contact Dermatitis Society core series of 70 allergens including BAK (0.1% aqueous). Initial readings were performed at 48 hours with final readings performed between 72 and 168 hours. Results were graded as + (weak: papules and erythema), ++ (strong: papules and edema or vesicles), or +++ (extreme: coalescing vesicles, spreading or bullous reactions). RESULTS: A total of 141 men (23%) and 475 women (77%) were tested (mean age, 49 years). Four hundred thirty-two (70%) were atopic. Of 615 patients, 198 (32%) tested positive to BAK, and 64 (10%) had ++ or +++ reactions at their final reading. On average, BAK-positive patients were using at least 1 product containing BAK or possible cross-reactors. CONCLUSIONS: Widespread exposure to irritants in dermatitis patients can predispose to sensitization. Products containing BAK or potential cross-reactors should be used carefully in patients with compromised skin barriers.