Word: melanin
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...birds are not the only things to suffer. Says Dr. Douglas Puppin, chairman of the dermatology department at the Federal University of Espirito Santo: "Ninety percent of the people I examine from that area have skin cancer or precancerous lesions." The reason: the light-skinned Pomeranians have far less melanin, a protective pigment, than most other, darker-skinned Brazilians. With the trees gone, says Puppin, "children are constantly in the sun. We try to warn them, but you can't expect kids to walk around in hats and long sleeves in the midday heat...
...dopa is the starting material for the synthesis of melanin, a pigment commonly found in skin cells affected by melanoma, a form of skin cancer. In the brain cells affected by neuroblastoma, another form of cancer, L-dopa serves as a starting material for the manufacture of norepinephrine, a chemical signal in the nervous system...
...manganese-poisoned miners had suffered chemical changes. He tried a chemical treatment. "It proved to be wrong," says the ebullient and totally unabashed Cotzias. Working on the analogous symptoms in parkinsonism at Brookhaven, he tried another drug treatment. This involved efforts to raise the brain's content of melanin, the pigment in suntanned skin. "Wrong again!" declares Cotzias, with the energy of a small volcano. "The patient's skin got darker, but the tremor got worse...
Reverse Selection. There remains the question of why the Mongols and related peoples are "yellow." Biochemist Loomis explains this on the basis of additional keratin (horny material) in the outer skin layers-though dermatologists deny this and say that the Mongol's sun screen is melanin, like the Negro's, but in smaller amounts. Loomis surmises that the yellow races may have developed their coloration after having gone through the white-race depigmentation phase. If migration away from the equator produces lighter skins, says Loomis, reverse migration could have the opposite effect. In the mere...
...hand throughout life. Babies of all races are lighter than adults, presumably reflecting nature's provision for early vitamin D needs. And people of all races have pale, unpigmented palms and soles. Since these parts have extra keratin and are not exposed to ultraviolet, they need no melanin protection against excess vitamin D synthesis...