To characterize aging as a factor responsible for structural changes the retinae of 47 Wistar-derived albino rats and 50 pigmented rats of the Norway and BDE (Han) strains between the ages of 1 and maximal 36 month were examined by light and electronmicroscopy and analysed for changes in cell densities. In all 3 rat strains there was an overall decline in nuclear densities of outer layer nuclei by 38 - 50% and inner layer nuclei by 27 - 33% between the ages of 1 and 27 months. Over the same age-range the ganglion cell loss was comparable to the decline in the inner nuclear layer. Neuronal cell death occurred at all ages and was more pronounced in albino rats. Moreover, in albino rats, cones were more resistant than rods to destruction by age and ambient light. Age-related ultrastructural changes in the retinal pigment epithelial cells (RPE) were in both pigmented strains: (1) a substantial accumulation of lipofuscin, (2) an apparent thickening of the basement membrane and (3) absent or greatly enlarged pleomorphic basal infoldings. In up to 27-month old BDE (Han) and 36-month old Norway rats besides mature stage IV-melanosomes also stage III-melanosomes can be observed. Characteristic of RPE-cells in old rats of these two strains were also compound granules and compound melanosomes. In peripheral RPE-cells of albino rats premelanosomes can be sporadically detected up to 31 months of age. Age-related changes in retinal vessels were found in the superficial and deep capillary network. The only finding was a 2-3 fold increase in thickness of the capillary basement membrane.
Department of Social Pharmacy, Institute of Pharmacology and Pharmacotherapy, Faculty of Pharmaceutical Sciences, University of Copenhagen, Universitetsparken 2, DK-2100, Copenhagen Ø, Denmark. firstname.lastname@example.org
To explore how ethnic minorities at risk of vitamin D deficiency are constructed in Danish policy documents (current as of April 2009), regarding vitamin D supplementation.
Ten policy documents were analysed through content analysis, focusing on definitions and explanations of ethnic minorities being at risk of vitamin D deficiency. This formed the basis for an analysis of constructions of ethnic minorities at risk which was undertaken using the Social Construction of Technology (SCOT) theory as an organising framework.
The analysis showed a high degree of interpretative flexibility regarding how ethnic minorities are constructed as a risk group for vitamin D deficiency. The ten documents analysed revealed eight different constructions of the ethnic minorities groups at risk. A low degree of interpretative flexibility was found regarding the importance of skin colour and skin covering. Major disagreements were found regarding the importance attributed to the Islamic religion, other traditions, immigration, gender and age, and use of an evolutionary explanation for the increased risk.
Ethnic minorities at risk of vitamin D deficiency are constructed very differently in Danish policies current as of April 2009. A more precise definition of ethnic minorities in policies and research may be helpful in seeking to identify which ethnic minorities are and are not at risk of vitamin D deficiency.
The last decade has witnessed important advances in our understanding of the genetics of pigmentation in European populations, but very little is known about the genes involved in skin pigmentation variation in East Asian populations. Here, we present the results of a study evaluating the association of 10 Single Nucleotide Polymorphisms (SNPs) located within 5 pigmentation candidate genes (OCA2, DCT, ADAM17, ADAMTS20, and TYRP1) with skin pigmentation measured quantitatively in a sample of individuals of East Asian ancestry living in Canada. We show that the non-synonymous polymorphism rs1800414 (His615Arg) located within the OCA2 gene is significantly associated with skin pigmentation in this sample. We replicated this result in an independent sample of Chinese individuals of Han ancestry. This polymorphism is characterized by a derived allele that is present at a high frequency in East Asian populations, but is absent in other population groups. In both samples, individuals with the derived G allele, which codes for the amino acid arginine, show lower melanin levels than those with the ancestral A allele, which codes for the amino acid histidine. An analysis of this non-synonymous polymorphism using several programs to predict potential functional effects provides additional support for the role of this SNP in skin pigmentation variation in East Asian populations. Our results are consistent with previous research indicating that evolution to lightly-pigmented skin occurred, at least in part, independently in Europe and East Asia.
Cites: Am J Phys Anthropol. 2000 May;112(1):17-2710766940
The majority of adolescents with skin of color in the United States and other westernized civilizations develop acne vulgaris. Indigenous populations of children and teenagers with skin of color may not develop acne when raised on a paleolithic diet, suggesting the Western diet is the rudiment of acne vulgaris. Differences exist in the presentation of and therapy for acne in teenagers with skin of color, largely due to the increased risk for hyperpigmentation, scarring, and keloid formation, as well as style- and skin care-related exacerbating factors. The primary goal of acne therapy in adolescents with skin of color is the prevention of long-term sequelae such as keloid formation. This article provides a brief overview of the treatment of acne vulgaris in adolescents with skin of color.
To describe the prevalence of sun exposure and protective behaviours during leisure time among Canadian adults 25 years of age or more.
A random-digit-dialling telephone household survey of 4023 people 15 years of age or more was completed; 3449 adults 25 years of age or more responded to questions about sun exposure and protective behaviours from June to August 1996.
Many of the adults (51%) reported getting 30 minutes to 2 hours of daily sun exposure, and 26% reported getting more than 2 hours. Half (50%) reported having one or more sunburns during the study period; 21% said they actively spent time suntanning. Less than half reported taking adequate protective actions. Women, light-complexioned and adults 65 years or more were more likely than men, medium- or dark-complexioned adults and adults in younger groups to protect themselves. Nearly two-thirds (63%) of the adults said they forgot to take protective actions, 47% felt it was inconvenient to do so, and 29% were not concerned about sun exposure.
Canadian adults, especially younger men, are exposed to significant amounts of sun during summer leisure time, but they do not always protect themselves adequately. Interventions should emphasize and facilitate convenient, effective sun protection strategies.
To describe the prevalence of sun exposure and protective behaviours among Canadian children 12 years of age or less, as reported by their parents.
A random-digit-dialling telephone household survey of 4023 people 15 years of age or more was completed in 1996; 1051 parents responded to questions about their children's sun-related behaviours from June to August 1996.
Most children (89%) had 30 minutes or more of daily sun exposure, and many of them (45%) had sunburns. The prevalence of sun protective actions ranged from 36% for avoiding the sun to 76% for using sunscreen. Parental reports on sun protection for children 5 years of age or less differed significantly from reports for children 6 to 12 years old.
High levels of sun exposure among Canadian children suggests the need for protection. Use of multiple methods of sun protection should be emphasized to parents, school personnel, recreation staff and child-care workers.
To describe the prevalence of sun exposure and protective behaviours during leisure time among Canadian youth 15 to 24 years of age.
A random-digit-dialling telephone household survey of 4023 people 15 years of age or more was completed in 1996; 574 youth responded to questions about their sun exposure and protective behaviours from June to August 1996.
Half of the youth (51%) reported 30 minutes to 2 hours of daily sun exposure, and 36% reported more than 2 hours. A large proportion (68%) reported sunburns. The prevalence of sun protective actions ranged from 38% for wearing a hat to 26% for both seeking shade and avoiding the sun between 11 am and 4 pm. There were sex differences in sun-related behaviours among youth.
The large proportion of Canadian youth who reported sun exposure and the small proportion who reported taking protective actions suggest the need for primary prevention. Interventions should address sex differences and focus on multiple methods of protection.