This study demonstrates that the production of reactive oxidizing species (e.g., hydroxyl radical (•OH)) during the photolysis of nitrite (NO2(-)) or nitrate (NO3(-)) leads to the oxidative conversion of arsenite (As(III)) to arsenate (As(V)). While the direct UV photolytic oxidation of As(III) was absent, nitrite (20 or 200 μM) addition markedly accelerated the oxidation of As(III) under UV irradiation (λ > 295 nm), which implies a role of NO2(-) as a photosensitizer for As(III) oxidation. Nitrate-mediated photooxidation of As(III) revealed an initial lag phase during which NO3(-) is converted into NO2(-). UV-Photosensitized oxidation of As(III) was kinetically enhanced under acidic pH condition where nitrous acid (HNO2) with a high quantum yield for •OH production is a predominant form of nitrite. On the other hand, alkaline pH that favors the photoinduced transformation of NO3(-) to NO2(-) significantly facilitated the catalytic reduction/oxidation cycling, which enabled the complete oxidation of As(III) at the condition of [As(III)]/[NO2(-)] ≫ 1 and markedly accelerated NO3(-)-sensitized oxidation of As(III). The presence of O2 and N2O as electron scavengers enhanced the photochemical dissociation of NO2(-) via intermolecular electron transfer, initiating the oxidative As(III) conversion route probably involving NO2• and superoxide radical anion (O2•(-)) as alternative oxidants. The outdoor experiment demonstrated the capability of NO2(-) for the photosensitized production of oxidizing species and the subsequent oxidation of As(III) into As(V) under solar irradiation.

IMPORTANCE Palmoplantar pustulosis (PPP) has been reported to be accompanied by systemic conditions. However, the risks of comorbidities in patients with PPP have rarely been evaluated. OBJECTIVE To assess the risks of comorbidities in patients with PPP compared with patients with psoriasis vulgaris or pompholyx.

<b><i>Background:</i></b> The inflammatory lesions of acne leave scars which greatly affect patients’ quality of life. Treatment options targeting both acne and acne scars are still lacking. <b><i>Objectives:</i></b> To evaluate the clinical efficacy of epidermal growth factor ointment (EGFO) on acne and acne scars. <b><i>Methods:</i></b> The study design was 12-week, prospective, split-face, single-blinded. The 36 patients with mild to moderate acne vulgaris applied EGFO on one side of the face and the vehicle ointment on the other side twice daily. The patients were assessed every 4 weeks by acne lesion and scar counts, investigator’s global assessment for acne (IGA) and scar (SGA), and the ECCA scar grading scale. Biopsies were performed before and after treatment. <b><i>Results:</i></b> Acne and acne scars were significantly improved on EGFO-treated sides, while control sides were not. Acne lesion and scar counts were significantly reduced after 4 weeks, while IGA, SGA, and ECCA grade significantly decreased after 8 weeks. Immunohistochemistry showed decreased expression of keratin 16, NF-κB p65, IL-1α, and IL-8, and increased expression of TGF-β₁, elastin, and collagen type 1, 3 after treatment. <b><i>Conclusions:</i></b> EGFO can be a treatment option targeting acne and acne scars.

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