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Biomedical subjects

L Petit

Publications and source records attributed to L Petit.

78 records · Page 5Linked to original sources

Ultraviolet light-enhanced visualization of cutaneous signs of carotene and vitamin A dietary deficiency.

Dietary deficiencies are multiple and some of them may induce specific changes in the skin biology and structure. Vitamin A deficiency is well identified as a cause of xerosis and follicular keratosis. Skin of the forehead and balding scalp was examined in 3 homeless alcoholic men who suffered from altered liver functions and denutrition including carotene and vitamin A deficiencies. The ultraviolet light-enhanced visualization (ULEV) method was used with a computer-assisted video camera equipped with an internal ultraviolet-emitting unit. Twenty healthy age- and phototype-matched men served as controls. Subclinical alterations of the stratum corneum and tiny follicular horny spikes at the skin surface were disclosed by ULEV. They were consistent with discrete flakiness on the forearms. By contrast, skin of the face and scalp showed follicular horny impactions corresponding to kerosis without any evidence for interfollicular xerosis. The skin condition was markedly improved after a 10-week dietary normalization. It is concluded that the ULEV method reveals some of the mildest and subclinical skin changes secondary to carotene and vitamin A deficiency. It could tentatively be used as a cheap and non-invasive aid in clinical screening programs among populations at risk.

Adult↗

[Signaling by melatonin receptors].

Melatonin is a hormone involved in various physiological processes such as the circadian cycle, hormone release and immune response. High-affinity melatonin receptors are classified in two pharmacologically distinct groups: Mel1 and Mel2. These receptors have first been localized in different organs and brain structures and some subtypes have since been cloned. Inhibition of adenylyl cyclase by Mel1 receptors is the best investigated signalling pathway but cannot be entirely responsible for the diversity of melatonin-induced phenomena. Phospholipase C, potassium ion channels and guanylyl cyclases have also been reported to be modulated by melatonin. This review updates present knowledge of the characterization and signalization of melatonin receptors.

Adenylyl Cyclase Inhibitors↗