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Nail pigmentation
Published in Robert Baran, Dimitris Rigopoulos, Chander Grover, Eckart Haneke, Nail Therapies, 2021
Robert Baran, Dimitris Rigopoulos
Periungual hyperpigmentation in newborns is a physiological melanic pigmentation observed during the early months of life. In addition, several types of acro pigmentation have been described in pediatric nail disorders (Baran, Hadj-Rabia, and Silverman 2017). In adults one has to rule out Hutchinson’s sign (Figure 17.1) from nonmelanoma Hutchinson’s sign.
Chromonychia
Published in Archana Singal, Shekhar Neema, Piyush Kumar, Nail Disorders, 2019
Michela Starace, Aurora Alessandrini, Bianca Maria Piraccini
A melanic pigmentation is a brown-black longitudinal band within the nail plate, while exogenous pigmentation includes different substances that adhere to the nail plate and does not usually have a longitudinal appearance, such as a subungual hematoma or Pseudomonas infection.
J.B.S. Haldane (1892–1964)
Published in Krishna Dronamraju, A Century of Geneticists, 2018
Haldane also considered analysis of the nearly complete replacement of light-colored moths, B. betularia, by a semidominant dark mutant form, which in the end became completely dominant, presumably by direct selection of modifiers. In a paper published in the Proceedings of the Royal Society of London in 1956, Haldane wrote: “Dr. Kettlewell’s proof that the dark form carbonaria of B. betularia has replaced the type, at least in part as the result of selection by bird predators, gives me the right to bring my calculation (Haldane 1924) on this matter up to date.” Haldane’s analysis of Kettlewell’s data led to new and unexpected conclusions: selection against the melanic form was generally much less intense than was found by Kettlewell, there may have been immigration of the lighter form from unpolluted areas into polluted areas, and selection has slowed down (selective advantage) due to some special reason. One such possibility is due to what geneticists call “balanced polymorphism,” which involves the existence of two kinds of melanic forms. Although they differ in their underlying genetic basis, they are indistinguishable externally.
Pharmacogenetics and drug metabolism: historical perspective and appraisal
Published in Xenobiotica, 2020
Robert L. Smith, Stephen C. Mitchell
The work of Archibald Edward Garrod (1857–1936) helped to fuse a liason between the emerging sciences of genetics, chemical pathology and biochemistry (physiological chemistry). His interest in alkaptonuria, helped cement the understanding that inefficiencies in enzyme pathways could lead to clinical conditions. This seminal work rested upon the ability to see a darkening of the urine caused by the oxidation of homogentisic acid (melanic acid), an intermediate in the breakdown of tyrosine and phenylalanine that accumulates owing to underactivity of homogentisic dioxygenase (Garrod, 1902). This outward clinical sign of darkening urine had been observed centuries ago (Scribonius, 1584) as mentioned by Garrod himself. His findings on alkaptonuria together with albinism, cystinuria and pentosuria (sometimes known as Garrod’s tetrad) were given in a series of four lectures, the Croonian lectures, in 1908 (Garrod, 1908) later published in book form (Garrod, 1909) (Figure 1). The revised second edition of his book included the other hereditary ailments of congenital steatorrhea and congenital porphyrinuria (Garrod, 1923).
Effects of device variables to radiofrequency (RF) applications
Published in Journal of Cosmetic and Laser Therapy, 2019
Metin Gorgu, Ali Gökkaya, Furkan Erol Karabekmez, Oktay Aytar, Jehat Kızılkan, Ertuğrul Karanfil, Hesna Müzeyyen Astarcı
After RF treatments, histologic changes like homogenization of the stratum corneum, partial detachment of the stratum corneum, follicular dilatation, arrangement of melanic pigment in irregular clusters, irregular areas of epidermal hyperplasia, expansion of the papillary dermis, the congestion and dilation of dermal blood vessels, edema, and increased dermal thickness were expected in biopsies (23). However, in our study, we did not observe remarkable changes in biopsies. We did not take biopsy samples from ex vivo material. In Nicoletti’s study, the changes in collagen with dermal heat increase were shown ex vivo (13). In our study, there were only in-vivo biopsies, that are taken immediately after RF application and in these biopsies we could not show the collagen changes. Most of the histologic changes are not expected to appear acutely after RF.