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  • 2020-2023  (2)
  • 2000-2004  (1)
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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Science Ltd
    British journal of dermatology 148 (2003), S. 0 
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Summary Background The cosmetic use of bleaching products is considered a common practice in dark-skinned women from sub-Saharan Africa. However, there are few studies on this subject. Objectives To increase the knowledge about the dermatological consequences of this practice in Dakar, the capital of Senegal. Methods A representative sample of 368 adult women presenting at our dermatological centre was selected. Each woman was questioned about her cosmetic use of bleaching products. Next, the following data were recorded in 425 women who used bleaching products: names and types of products used; modalities of the skin bleaching practice; skin diseases motivating the dermatological visit, with recording of their clinical features; and results of a full skin examination. The active substances of the bleaching products were determined mainly by reading the indications on their packages; with products of unknown composition, a pharmacological analysis of samples was done. A statistical analysis was performed. Results Of the 368 women questioned, 194 (52·7%) were current users of bleaching products. Concerning the 425 users enrolled, products were applied on the whole body in 92% of users, with a median duration of use of 4 years. The active principles used included hydroquinone (used by 89% of users), glucocorticoids (70%), mercury iodide (10%) and caustic agents (17%); 13% of users used products of unknown composition. In the samples that were analysed, hydroquinone was found at concentrations of between 4% and 8·7%. Concerning steroids, superpotent (class 1) glucocorticoids predominated. The main skin complaints in bleaching products users included dermatophyte infections (n = 105) and scabies (n = 69), both often unusually extensive and severe; acne (n = 42), often severe; eczema (n = 41); irritant dermatitis (n = 14); and dyschromia (n = 26, including 14 cases of exogenous ochronosis). The skin examination noted features apparently disregarded by users: striae (noticed in 39% of users), and macular hyperchromia involving the face, mainly the periocular area (33%). The statistical analysis showed that glucocorticoid use was associated with the presence and severity of infectious skin diseases, and of acne. Conclusions More than half of the adult women presenting at our dermatology centre were using bleaching products. Most skin diseases observed in bleaching products users appeared to be induced, aggravated or modified by this practice. Superpotent topical glucocorticoids appeared to be the main agents responsible for the observed complications. The cosmetic use of bleaching products therefore has a major impact on our current dermatological practice.
    Type of Medium: Electronic Resource
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  • 2
    Publication Date: 2022-02-16
    Description: One of the most fundamental questions in ecology is how many species inhabit the Earth. However, due to massive logistical and financial challenges and taxonomic difficulties connected to the species concept definition, the global numbers of species, including those of important and well-studied life forms such as trees, still remain largely unknown. Here, based on global ground-sourced data, we estimate the total tree species richness at global, continental, and biome levels. Our results indicate that there are ∼73,000 tree species globally, among which ∼9,000 tree species are yet to be discovered. Roughly 40% of undiscovered tree species are in South America. Moreover, almost one-third of all tree species to be discovered may be rare, with very low populations and limited spatial distribution (likely in remote tropical lowlands and mountains). These findings highlight the vulnerability of global forest biodiversity to anthropogenic changes in land use and climate, which disproportionately threaten rare species and thus, global tree richness.
    Language: English
    Type: info:eu-repo/semantics/article
    Format: application/pdf
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  • 3
    Publication Date: 2022-11-18
    Description: The latitudinal diversity gradient (LDG) is one of the most recognized global patterns of species richness exhibited across a wide range of taxa. Numerous hypotheses have been proposed in the past two centuries to explain LDG, but rigorous tests of the drivers of LDGs have been limited by a lack of high-quality global species richness data. Here we produce a high-resolution (0.025° × 0.025°) map of local tree species richness using a global forest inventory database with individual tree information and local biophysical characteristics from ~1.3 million sample plots. We then quantify drivers of local tree species richness patterns across latitudes. Generally, annual mean temperature was a dominant predictor of tree species richness, which is most consistent with the metabolic theory of biodiversity (MTB). However, MTB underestimated LDG in the tropics, where high species richness was also moderated by topographic, soil and anthropogenic factors operating at local scales. Given that local landscape variables operate synergistically with bioclimatic factors in shaping the global LDG pattern, we suggest that MTB be extended to account for co-limitation by subordinate drivers.
    Type: info:eu-repo/semantics/article
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