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.
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.
3-diphenylguanidine, carba mix, case report, diphenyl thiourea, occupational allergic contact dermatitis, rubber accelerator, surgical sponge Less well-recognized sources of rubber accelerators, including surgical scrub sponges, are important exposures to consider in surgical personnel experiencing occupationally induced hand and/or forearm dermatitis. ISAAC ET AL. 149 CASE REPORT A 30-year-old man presented with 8 years of bilateral hand dermatitis that started during medical school and continued into his surgical residency. At work, he frequently applied hand sanitizer, scrubbed his arms and hands before cases, and wore nitrile gloves. His hand dermatitis was previously treated with topical corticosteroids. His symptoms improved during extended periods outside the hospital.His hand and forearm dermatitis was well controlled during our initial evaluation, as he had been performing a research elective rather than clinical work. He was tested with our baseline, cosmetics, fragrance, rubber and bakery series (Chemotechnique Diagnostics, Vellinge, Sweden). The following occupational products were also tested: hand sanitizer, three surgical scrub sponges, two nitrile gloves, and 5% dilutions of two hand soaps and three surgical scrub solutions.Allergens were occluded under Finn Chambers (SmartPractice, Phoenix, Arizona), fixed with 3M Micropore tape, and removed after 2 days.On day (D) 3, the patient showed reactions to 1,3-diphenylguanidine (DPG) (+++), carba mix (++), diphenyl thiourea (+), shellac (++), 2-bromo-2-nitropropane-1,3-diol (Bronopol) (+), propolis (+), cobalt chloride (+), Disperse Blue 153 (+), dimethyl dihydroxyethyleneurea (+), dimethylol dihydroxyethyleneurea (+), geraniol (+), Mentha piperita oil (+), linalool (+), and Juniperus oxycedrus extract (+). He also had positive reactions to one hand soap (+) and one glove (+), and a +++ reaction to the BD E-Z 116 surgical scrub sponge (Figure 1). We diagnosed him with occupationally induced hand dermatitis secondary to fragrances in hand soaps and suspected rubber accelerators in his nitrile gloves and surgical scrub sponge. Although his exposure to the sponge was not as long in duration as his exposure to the gloves, the scrubbing procedure involves friction and contact with water for several minutes; therefore, the combined effects of rubber additives in the sponge and gloves, friction, and humidity all probably contributed to his symptoms. DISCUSSION Sensitization to rubber accelerators among healthcare workers (HCWs) is common. The estimated prevalence of rubber allergy inHCWs is up to 22%, as compared with 12% in the general US population. 1 Operating room personnel and atopic individuals are at higher risk of sensitization. 1,2 In a study of 425 HCWs, 17 of 22 patients with occupational contact allergy to gloves showed reactivity to rubber additives, most commonly DPG. 3 Hand dermatitis associated with non-natural rubber latex gloves is well established. 2,3 However, additional exposures, such as surgical scrub sponges, should also be considered i...
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