https://www.thelancet.com/pdfs/journals/lancet/PIIS0140-6736(00)04046-0.pdf

Inflammation and cancer: back to Virchow?

Bcl-2 functions in an antioxidant pathway to prevent apoptosis

A review of reported tissue optical properties summarizes the wavelength-dependent behavior of scattering and absorption. Formulae are presented for generating the optical properties of a generic tissue with variable amounts of absorbing chromophores (blood, water, melanin, fat, yellow pigments) and a variable balance between small-scale scatterers and large-scale scatterers in the ultrastructures of cells and tissues.

/pdf/optical-properties-of-biological-tissues-a-review-2bu6kxou63.pdf

Optical properties of biological tissues: a review.

Rook's textbook of dermatology , Rook's textbook of dermatology , کتابخانه مرکزی دانشگاه علوم پزشکی ایران

Rook's Textbook of Dermatology

Medical genetics was revolutionized during the 1980s by the application of genetic mapping to locate the genes responsible for simple Mendelian diseases. Most diseases and traits, however, do not follow simple inheritance patterns. Geneticists have thus begun taking up the even greater challenge of the genetic dissection of complex traits. Four major approaches have been developed: linkage analysis, allele-sharing methods, association studies, and polygenic analysis of experimental crosses. This article synthesizes the current state of the genetic dissection of complex traits—describing the methods, limitations, and recent applications to biological problems.

Genetic Dissection of Complex Traits

PART I: THE PHYSIOLOGY OF THE PIGMENTARY SYSTEM SECTION 1: HISTORICAL & COMPARATIVE PERSPECTIVES OF THE PIGMENT SYSTEM SECTION 2: THE MORPHOLOGY, DISTRIBUTION & BIOLOGY OF THE PIGMENT CELL SECTION 3: THE MOLECULAR BIOLOGY OF THE PIGMENT CELL SECTION 4: CHEMISTRY & PHYSICS OF MELANIN AND ENZYMOLOGY OF MELANIN SYNTHESIS PART II: THE PATHOPHYSIOLOGY OF THE PIGMENTARY SYSTEM SECTION 5: AN OVERVIEW OF HUMAN SKIN COLOR AND ITS DISORDERS SECTION 6: DISORDERS OF HYPOPIGMENTATION AND DEPIGMENTATION SECTION 7: DISORDERS OF HYPERPIGMENTATION SECTION 8: TREATMENT OF PIGMENTARY DISORDERS

The pigmentary system : physiology and pathophysiology

alpha-Melanocyte stimulating hormone (alpha-MSH) and ACTH increase the proliferation and melanogenesis of cultured human melanocytes. To further analyze how melanotropins produce these biological effects, we investigated the regulation of the melanocortin receptor MC1R expression by alpha-MSH and ACTH using Northern blot analysis and determine the relative affinity of the receptor for the structurally similar peptides alpha-MSH, ACTH, beta-MSH, and gamma-MSH. We also determined the relative potencies of these hormones to stimulate cAMP formation, tyrosinase activity, and melanocyte proliferation. The order of affinity and potency of the noted melanotropins in these assays were alpha-MSH = ACTH > beta-MSH > gamma-MSH. Because the binding affinity of each of these melanotropins for the MC1R correlated with its ability to stimulate human melanocyte proliferation and melanogenesis, we conclude that these effects are mediated specifically by binding to and activation of the MC1R. gamma-MSH stimulated cAMP formation without affecting proliferation or melanogenesis. However, we found that relative to alpha-MSH, the effect of gamma-MSH on cAMP formation was transient. Our results suggest that alpha-MSH, ACTH, and possibly beta-MSH, but not gamma-MSH, are capable of a physiological role in regulating human pigmentation, and that melanocytes in human skin are a specific target for these hormones.

/pdf/binding-of-melanotropic-hormones-to-the-melanocortin-1urfdedv90.pdf

Binding of melanotropic hormones to the melanocortin receptor MC1R on human melanocytes stimulates proliferation and melanogenesis

We have identified and studied twenty-seven patients with melanoma who also had vitiligo. Four patients had vitiligo before the diagnosis of melanoma, and twenty-three developed depigmentation after the diagnosis of malignancy. We also have reviewed published reports about twenty-four other patients with melanoma who developed vitiligo. The clinical course of the melanoma in the fifty-one patients was remarkably similar. Thirty-seven had a melanoma arising at a site which tends to carry a poor prognosis, for example, on the trunk, under the nail, or on the mucous membranes. Forty-nine patients had metastases in regional lymph nodes or at distal sites. Thirty-three patients survived 5 years, and twenty-five survived 10 years. These data suggest that the appearance of vitiligo in patients with metastatic melanoma portends a longer survival than expected. The patients with vitiligo are not necessarily cured and eventually may succumb to metastatic disease. We were unable to determine whether the vitiligo caused retardation of tumor growth or whether the melanoma caused vitiligo.

Vitiligo in patients with metastatic melanoma: a good prognostic sign.

The total mass of pigment cells in the adult human is estimated to be about 1.5 grams (1). This mass of pigment cells is substantially larger than the pineal gland which weighs only 100 mg. Despite its small size, the pineal gland is responsible for adjusting the body's intrinsic cycles to daily and seasonal environmental variables such as sunlight, temperature and food availability (2). The pituitary gland, the reputed conductor of the endocrine orchestra, weighs about 500 mg. In contrast to these two glands, pigment cells are dispersed throughout many organs, for example the skin, eyes, ears. meninges and other tissues. Because they are scattered throughout the body, they are considered of little biological importance. There is a tendency for dermatologists to ignore the concept of a pigment system, and to think only of isolated pigment cells. It has been stated that a patient can live essentially a \"normal\" life with nonfunctioning melanocytes (oculocutaneous albinism) or without any cutaneous melanocytes at all (piebaldism or total vitiligo). This idea probably is incorrect because pigment and pigment cells are involved in many important activities of the skin and other organs.

The pigmentary system: new interpretations of old data.

We studied the effects of prolonged ingestion of melatonin, 1 g per day, on skin color and the serum levels of pituitary hormones in 5 human subjects with hyperpigmented skin. Melatonin lightened hyperpigmented skin of one patient with untreated adrenogenital syndrome, but had no effect on three patients' skin with idiopathic hyperpigmentation and one patient with treated Addison's disease. Melatonin appeared to depress the level of luteinizing hormone (LH) in serum and may have inhibited in some patients the release of growth hormone from the pituitary gland after stimulation by stress or L-dopa. The subjects all noted increased drowsiness but through studies on the eyes, liver, kidneys, and bone marrow revealed no other evidence of toxicity.

James J. Nordlund

Papers

The pigmentary system : physiology and pathophysiology

Binding of melanotropic hormones to the melanocortin receptor MC1R on human melanocytes stimulates proliferation and melanogenesis

Vitiligo in patients with metastatic melanoma: a good prognostic sign.

The pigmentary system: new interpretations of old data.

The effects of oral melatonin on skin color and on the release of pituitary hormones.