Blue-Gray Discoloration Associated With Ezogabine

Additional Contributions: Talmon Arad and Smadar Zaidman, PhD, Irving and Cherna Moskowitz Center for Nano and Bio-Nano Imaging, Weizmann Institute of Science, conducted the electron microscopy studies. Ana Tovar, MD, Institute of Pathology, Beilinson Hospital, assisted with electron microscopy data analysis. There was no financial compensation for these contributions. REFERENCES 1. Stafstrom CE, Grippon S, Kirkpatrick P. Ezogabine (retigabine). Nat Rev Drug Discov. 2011;10(10): 729-730. 2. Amabile CM, Vasudevan A. Ezogabine: a novel antiepileptic for adjunctive treatment of partial-onset seizures. Pharmacotherapy. 2013;33 (2):187-194. 3. Ciliberto MA, Weisenberg JL, Wong M. Clinical utility, safety, and tolerability of ezogabine (retigabine) in the treatment of epilepsy. Drug Healthc Patient Saf. 2012;4:81-86. 4. Ming ME, Bhawan J, Stefanato CM, McCalmont TH, Cohen LM. Imipramine-induced

Case Report/Case Series Research

hyperpigmentation: four cases and a review of the literature. J Am Acad Dermatol. 1999;40(2, pt 1): 159-166.

11. Köstler E, Porst H, Wollina U. Cutaneous manifestations of metabolic diseases: uncommon presentations. Clin Dermatol. 2005;23(5):457-464.

5. Smith RW, Leppard B, Barnett NL, Millward-Sadler GH, McCrae F, Cawley MI. Chrysiasis revisited: a clinical and pathological study. Br J Dermatol. 1995;133(5):671-678.

12. Bolognia JL, Jorizzo JL, Schaffer JV. Dermatology. 3rd ed. Oxford, England: WB Saunders; 2012.

6. Massi D, Santucci M. Human generalized argyria: a submicroscopic and X-ray spectroscopic study. Ultrastruct Pathol. 1998;22(1):47-53. 7. Wadhera A, Fung M. Systemic argyria associated with ingestion of colloidal silver. Dermatol Online J. 2005;11(1):12. 8. Zachary CB, Slater DN, Holt DW, Storey GC, MacDonald DM. The pathogenesis of amiodarone-induced pigmentation and photosensitivity. Br J Dermatol. 1984;110(4):451-456. 9. Hendrix JD Jr, Greer KE. Cutaneous hyperpigmentation caused by systemic drugs. Int J Dermatol. 1992;31(7):458-466. 10. Dereure O. Drug-induced skin pigmentation: epidemiology, diagnosis and treatment. Am J Clin Dermatol. 2001;2(4):253-262.

13. Lerner EA, Sober AJ. Chemical and pharmacologic agents that cause hyperpigmentation or hypopigmentation of the skin. Dermatol Clin. 1988;6(2):327-337. 14. US Food and Drug Administration. FDA Drug Safety Communication: anti-seizure drug Potiga (ezogabine) linked to retinal abnormalities and blue skin discoloration. April 26, 2013. http://www.fda.gov/Drugs/DrugSafety /ucm349538.htm. Accessed May 7, 2013. 15. US Food and Drug Administration. FDA Drug Safety Communication: FDA approves label changes for anti-seizure drug Potiga (ezogabine) describing risk of retinal abnormalities, potential vision loss, and skin discoloration. October 10, 2013. http://www.fda.gov/Drugs/DrugSafety /ucm372774.htm. Accessed May 14, 2014.

NOTABLE NOTES

Saving Their Skins How Animals Protect From the Sun Sowmya Varada, BS; Dana Alessa, MD

A distinctive evolutionary change experienced by our ancestors as they branched away from their fellow apes was the loss of body hair. While this may have had certain benefits, our species has also suffered drawbacks; for one, without thick fur or hair to scatter sunlight, our skin is more susceptible to burning in the sun. Indeed, sunburns have been observed in other relatively hairless members of the animal kingdom, including whales, dolphins, fish, elephants, and rhinoceroses. But just as humans have evolved physiologic and behavioral adaptations to protect from the sun, other creatures too have developed their own. Whales have hairless, streamlined bodies and frequently travel to the sea surface for air, making them particularly vulnerable to UV-induced skin damage. The sperm whale, which spends up to 6 hours at a time at the surface, is known to activate genotoxic stress pathways in response to persistent UV exposure.1 While the fin whale possesses constitutively high levels of melanin, the blue whale modulates its skin melanin throughout the year, becoming darker when UV levels are highest from February to May.1 This adaptive pigmentation has also been observed in hammerhead sharks and some fish. Equatorial Africa, which receives abundant daily sunlight year round, is home to the world’s 3 largest pachyderms: the elephant, rhinoceros, and hippopotamus, for whom learned behaviors are essential for sun protection. The African elephant uses its prehensile trunk to throw dust onto its back, the rhinoceros wallows in and coats itself with mud, and the hippopotamus submerges itself in water.2 The hippopotamus also possesses a curious adaptation found in no other animal—it manufactures its own sunscreen. The hippopotamus’s “blood sweat” is a thick, reddish fluid that is neither blood nor true sweat, as the animal’s skin contains no sebaceous glands. It is secreted by subdermal glands through

jamadermatology.com

large skin pores and contains 2 pigments, hipposudoric acid and norhipposudoric acid, whose polymerization gives the fluid a reddish orange color and whose absorption of UV light makes this substance a highly effective sunscreen.3 Some animals are well covered with fur but may need to protect other body parts from the sun. A giraffe’s long tongue, frequently outstretched to forage the treetops for leaves, is colored blackish purple from the circumvallate papillae to the tip, believed to protect it from sunburn.2 The meerkat’s eyes are surrounded by dark bands to reduce sun glare, and the nictitating membrane covering a polar bear’s eye filters bright sunlight reflected by the snow. Increasing UV exposure from a depleted ozone layer will certainly exert a selective pressure on animals to evolve more sophisticated skin defenses. Studying these creatures may provide greater insight into skin physiology and how our own species will adapt to a changing solar environment. Author Affiliations: Jefferson Medical College, Philadelphia, Pennsylvania (Varada); Tufts Medical Center, Boston, Massachusetts (Alessa). Corresponding Author: Sowmya Varada, BS, Jefferson Medical College, 53 Loomis St, Bedford, MA 01730 ([email protected]). 1. Martinez-Levasseur LM, Gendron D, Knell RJ, O’Toole EA, Singh M, Acevedo-Whitehouse K. Acute sun damage and photoprotective responses in whales. Proc Biol Sci. 2011;278(1711):1581-1586. 2. Gambino M. Ask an expert: do animals get sunburned? Smithsonian Magazine. 2011. http://www.smithsonianmag.com/science-nature/ask-an-expert-do-animals -get-sunburned-28218217/?no-ist. Accessed November 12, 2013. 3. Saikawa Y, Hashimoto K, Nakata M, et al. Pigment chemistry: the red sweat of the hippopotamus. Nature. 2004;429(6990):363.

JAMA Dermatology September 2014 Volume 150, Number 9

Copyright 2014 American Medical Association. All rights reserved.

Downloaded From: http://archderm.jamanetwork.com/ by a University of Georgia User on 05/29/2015

989

Saving their skins: how animals protect from the sun.

Saving their skins: how animals protect from the sun. - PDF Download Free
44KB Sizes 3 Downloads 8 Views