Indermeet Kohli

The impact of oral Polypodium leucotomos extract on ultraviolet B response: A human clinical study

Background There is a rationale for adding systemic photoprotective agents to the current photoprotection regimen. Objective This study was designed to objectively evaluate the molecular and photobiologic effects of oral administration of Polypodium leucotomos extract (PLE). Methods In all, 22 subjects with Fitzpatrick skin phototype I to III were enrolled. On day 1, subjects were irradiated with visible light, ultraviolet (UV) A1, and UVB (using 308‐nm excimer laser). Evaluation was done immediately and 24 hours after irradiation. On days 3 and 4, irradiation and evaluation process was repeated after ingestion of PLE. Results Clinical assessments and colorimetry data showed a decrease in UVB‐induced changes in 17 of 22 subjects post‐PLE administration; histology findings demonstrated such a decrease in all 22 subjects. Limitations Only 2 doses of PLE were given. Furthermore, subjects with skin phototypes I to III only were studied. Conclusion The results suggest that PLE can potentially be used as an adjunctive agent to lessen the negative photobiologic effects of UVB. Abbreviations used: COX‐2: cyclooxygenase‐2; IGA: Investigator Global Assessment; MED: minimal erythema dose; PLE: Polypodium leucotomos extract; UV: ultraviolet.

Three‐dimensional imaging of vitiligo

Keywords: body Surface Area (BSA); imaging; Measurement error; three dimensional; vitiligo

Synergistic Effects of Long Wavelength Ultraviolet A1 and Visible Light on Pigmentation and Erythema

Visible light (VL) induces multiple cutaneous effects. Sunscreen testing protocols recommended by regulatory bodies throughout the world require the use of solar simulators with spectral output in the ultraviolet (UV) domain only. However, sunlight contains VL and infrared radiation also.

Clinical and Biological Relevance of Visible and Infrared Radiation

Visible and infrared radiation spectra have numerous biological and clinical effects on the skin. Visible spectrum radiation can induce transient erythema and persistent pigmentation and can also induce free radical production along with DNA damage. Visible light also plays a role in the pathogenesis of solar urticarial, chronic actinic dermatitis, and porphyrias and is used in the treatment of hyperbilirubinemia and acne vulgaris. Infrared radiation is capable of inducing erythema, thermal pain, and photoaging in addition to cytotoxicity, DNA damage, and oxidative stress. Infrared radiation can also cause erythema ab igne and plays a role in the treatment of acne vulgaris. Lasers in the visible and infrared spectrum have been widely used in the treatment of a variety of dermatologic conditions such as vascular and pigmented lesions and keloids. Photoprotection from visible and infrared radiation and diagnostic imaging using visible and infrared radiation are important topics that have recently been explored.

The potential role of antioxidants in mitigating skin hyperpigmentation resulting from ultraviolet and visible light-induced oxidative stress

Oxidative stress is an integral element that influences a variety of biochemical reactions throughout the body and is known to play a notable role in melanogenesis. Exogenous triggers of oxidative stress, such as ultraviolet radiation (UVR) and visible light (VL), lead to pigment formation through somewhat different pathways, but both share a common endpoint—the potential to generate cosmetically undesirable hyperpigmentation. Though organic and inorganic sunscreens are available to protect against the UVR portion of the electromagnetic spectrum, coverage is lacking to protect against the VL spectrum. In this manuscript, we review the phases of tanning, pathways of melanogenesis triggered by UVR and VL, and the associated impact of oxidative stress. We also discuss the known intrinsic mechanisms and paracrine regulation of melanocytes that influence their response to UVR. Understanding these mechanisms and their role in UVR‐induced hyperpigmentation should potentially lead to identification of useful targets that can be coupled with antioxidant therapy to alleviate this effect.

Automated Melasma Area and Severity Index scoring

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