The hair eclipse phenomenon: sharpening the focus on the hair cycle chronobiology.

in International Journal of Cosmetic Science (2003), 25(6), 295-9

Chronobiology governing the hair cycle is a fascinating and complex process. Both the hair growth cycle and the hair shaft growth are coordinated and depend on the interplay of different biological ... [more ▼]

Chronobiology governing the hair cycle is a fascinating and complex process. Both the hair growth cycle and the hair shaft growth are coordinated and depend on the interplay of different biological signals and various exogenous stimuli. A latency period may occur between hair shedding (teloptosis, exogen phase) and the early emergence of the next anagen VI stage. This lag time referred to on the hair eclipse phenomenon likely depends on the influence of a series of distinct synchronizers, and does not represent per se a peculiar hair cycle phase. It is the result of some dysregulations of the hair cycling, involving early teloptosis, delayed anagen I initiation or stunted hair growth at any stage between the anagen I and anagen V phases. As such, the hair eclipse phenomenon may be an erratic process occurring in physiopathological conditions affecting hair follicles singly or in focal to generalized patterns. It may be more frequent when it follows synchronized teloptosis occurring in telogen effluvium (newborn alopecia, post-partum alopecia, seasonal alopecia and alopecia areata). It may also be prominent when microinflammation is abutted on the permanent portion of the hair follicle as in dandruff, seborrhoeic dermatitis, androgenic alopecia and photoageing baldness. Local synchronizers such as growth factors and other mediators may eventually be lacking or involved in the hair eclipse phenomenon. Their identification and characterization might drive new corrective or preventive applications. [less ▲]

Pharma clinics. Le médicament du mois. L'imiquimod (Aldara): un immunomodulateur pour la peau.

in Revue Médicale de Liège (2002), 57(2), 116-8

Imiquimod is the first drug of a new therapeutic class encompassing cutaneous immune response modifiers. This molecule induces the synthesis and release of macrophage-related cytokines. It boosts some ... [more ▼]

Imiquimod is the first drug of a new therapeutic class encompassing cutaneous immune response modifiers. This molecule induces the synthesis and release of macrophage-related cytokines. It boosts some local immune responses. These properties are used to treat cutaneous viral condylomas. Other prospective therapeutic goals are presently scrutinized. [less ▲]

Analytic Quantification of Phototype-Related Regional Skin Complexion

in Skin Research & Technology : Official Journal of International Society for Bioengineering & the Skin (ISBS) [and] International Society for Digital Imaging of Skin (ISDIS) [and] International Society For... (2001), 7(3), 168-71

BACKGROUND/AIMS: Narrow-band spectrophotometry that yields melanin (M) and erythema (E) indexes is a convenient method for assessing skin colour. The objective of the study was to assess the phenotype ... [more ▼]

BACKGROUND/AIMS: Narrow-band spectrophotometry that yields melanin (M) and erythema (E) indexes is a convenient method for assessing skin colour. The objective of the study was to assess the phenotype-associated body site differences in skin complexion. METHOD: The Mexameter MX16 was used to record the skin colour in 137 subjects. Evaluations were made on the inner arm, volar forearm, dorsal forearm and forehead. RESULTS: The inner arm and volar forearm had similar values for each of the colorimetric values. The dorsal forearm exhibited the highest M values, and the forehead had the highest E values. Significant positive linear correlations were found between M values from the distinct body sites. The E values showed a correlation only between the inner arm and the volar forearm. CONCLUSION: Regional skin colour differences are obvious. Sun-exposed skin does not react in the same way on the forearm and forehead. Regional variations in M can be predicted from the innate M value. In contrast, the regional variability in E is highly variable among subjects. [less ▲]