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Abstracts

Abstracts

Antioxidants (Sunburn)

Antioxidants

Natural compounds, anti-oxidants in particular, may be used in photoprotection. Two of the best known anti-oxidants are vitamins C and E, both of which have been shown to be somewhat effective in different models of photodamage.

Report that (in swine skin) vitamin C is capable of additive protection against acute UVB damage (sunburn cell formation) when combined with a UVB sunscreen.

A combination of both vitamins E and C provided very good protection from a UVB insult, the bulk of the protection attributable to vitamin E.

However, vitamin C is significantly better than vitamin E at protecting against a UVA-mediated phototoxic insult in this animal model, while the combination is only slightly more effective than vitamin C alone.

When vitamin C or a combination of vitamin C and E is formulated with a commercial UVA sunscreen (oxybenzone), an apparently greater than additive protection is noted against the phototoxic damage.

Darr D et al., Effectiveness of antioxidants (vitamin C and E) with and without sunscreens as topical photoprotectants. Acta Derm Venereol, 76(4):264-8 1996 Jul.

Beta-carotene

Beta-carotene

Evaluated the efficacy of 10 weeks of moderate dose (30 mg/d) "beta-carotene" (BC) on plasma and "skin" beta-carotene levels during 12 days of time and intensity controlled sunlight exposure at sea level (30 degrees latitude, Red Sea, Eilath, Israel).

After 12 days of controlled sun exposure (total UV dose of about 10.000J/cm2), plasma beta-carotene decreased in the placebo and beta-carotene group (not significant).

In addition cutaneous beta-carotene decreased significantly in both groups. Plasma alpha-"tocopherol" decreased significantly during exposure time in both groups. In the supplemented group, however, the decrease of a-tocopherol was significantly greater than in the placebo group.

Sunlight influences the b-carotene and alpha-tocopherol content of "blood" and tissues.

Biesalski-HK et al: Effects of controlled exposure of sunlight on plasma and skin levels of beta-carotene. Free-Radic-Res. 1996 Mar; 24(3): 215-24.

Children (New Zealand)

Children (New Zealand)

Examined the extent of sun exposure, sun protection and experience of sunburn among young New Zealand children on summer weekends.

Over 90% of the children were reported to be outside on the preceding Saturday and/or Sunday; 7% of those outside experienced some degree of sunburn. The worst burning was on the face, head, neck or ears. On either day about half the children were wearing sunscreen and 60% were wearing a hat.

Parental use of sun protection was the strongest predictor of sun protection among the children.

Many children in the community are still at high risk of sunburn. Efforts to promote sun protection as a family responsibility may reduce burning among the young.

McGee R et al., Sunburn and sun protection among young children. J Paediatr Child Health, 33(3):234-7 1997 Jun.

Melanoma (1)

Melanoma (1)

Reviewed the current epidemiologic and experimental evidence regarding the effect of sunburns on cutaneous malignant melanoma and the possible effectiveness of sunscreens in preventing those effects.

There is growing agreement that sunlight exposure, particularly the ultraviolet wavelengths in solar radiation, contributes to the etiology of cutaneous malignant melanoma, there are insufficient data on whether the use of sunscreens may be useful in preventing melanoma.

The exact role of sunlight in the pathogenesis of melanoma still remains undefined.

Donawho C & Wolf P: Sunburn, sunscreen, and melanoma. Curr Opin Oncol, 8(2):159-66 1996 Mar.

Melanoma (2)

Melanoma (2)

Analysed the relationship between the anatomic site of cutaneous melanoma, sun exposure, and phenotype women (# 355) with histologically confirmed superficial-spreading melanoma and in 935 control subjects.

The most frequent site for superficial-spreading melanoma was the leg. However, when major sun-related and phenotype risk factors were examined by site, risk ratios were lowest for melanomas that occurred on the leg. A history of frequent sunburns during elementary or high school, increased number of self-assessed large nevi, and blond hair were more strongly associated with melanoma sites other than the leg.

"Tumors" on the trunk were more likely than tumors at other sites to be associated with histological evidence of a preexisting nevus.

Associations between melanoma phenotypic factors may differ by anatomic site.

Cress RD et al: Cutaneous melanoma in women: anatomic distribution in relation to sun exposure and phenotype. Cancer Epidemiol Biomarkers Prev (ISSN 1055-9965) Vol. 4 no. 8 pp. 831-6.

Nevi

Nevi

The associations of sun exposure, sunburn, skin color, and other constitutional characteristics with the density of nevi (2 mm or more in diameter) were assessed in a study of 410 secondary school children ages 14-15 years in Tasmania, Australia.

Skin color was estimated by using a chromameter that measures across the visible light spectrum (400-700 nm). Skin color and lifetime history of sunburn were significant predictors of nevus density on the arms and legs of girls and boys and on the shoulders and backs of boys.

The increase in nevus density appeared to occur at lower levels of lifetime sunburn in children with light or medium skin than it did in children with darker skin. Darker-skinned children with a history of many sunburns ( > or = 11 lifetime sunburns) had a similar number of nevi compared with their lighter-skinned peers.

Dwyer T et al: Sunburn associated with increased number of nevi in darker as well as lighter skinned adolescents of northern European descent. Cancer Epidemiol Biomarkers Prev (ISSN 1055-9965) Vol. 4 no. 8 pp. 825-30.

Silymarin

Silymarin

Nonmelanoma skin cancer is the most common cancer. Therefore, it is important to identify agents that can offer protection against this cancer.

Evaluated the protective effects of silymarin, a flavonoid compound isolated from the milk thistle plant, against UVB radiation-induced nonmelanoma skin cancer in mice and delineated the mechanism(s) of its action.

Silymarin was applied topically at a dose of 9 mg per application before UVB exposure, and evaluated relative to: tumor incidence (% of mice with tumors), tumor multiplicity (number of tumors per mouse), and average tumor volume.

In UVB-induced tumor initiation, silymarin treatment reduced tumor incidence from 40% to 20%, tumor multiplicity by 67%, and tumor volume per mouse by 66%.

In UVB-induced tumor promotion, silymarin treatment reduced tumor incidence from 100% to 60%, tumor multiplicity by 78%, and tumor volume per mouse by 90%.

The effect of silymarin was much more profound in the protocol with UVB-induced complete carcinogenesis, where tumor incidence was reduced from 100% to 25%, tumor multiplicity by 92%, and tumor volume per mouse by 97%. In short-term experiments, silymarin application resulted in statistically significant inhibition in UVB-caused sunburn and apoptotic cell formation, skin edema, depletion of catalase activity, and induction of COX and ODC activities and ODC mRNA expression.

Silymarin can provide substantial protection against different stages of UVB-induced carcinogenesis, possibly via its strong antioxidant properties.

Katiyar SK et al., Protective effects of silymarin against photocarcinogenesis in a mouse skin model. J Natl Cancer Inst, 89(8):556-66 1997 Apr 16.

Skin Cancer - Australia

Skin Cancer - Australia

Described changes in skin protection attitudes and outdoor behaviors of adults in Queensland, Australia.

However, recent sunburn experience remained unchanged.

A similar study in Victoria, Australia, observed changes in skin protection attitudes, behaviors, and recent sunburn.

Speculated on possible explanations for the lack of improvement in recent sunburn experience despite the improvement in skin protection attitudes, and behaviors, and suggest that part of the explanation may be environmental differences.

Baade PD et al., Changes in skin protection behaviors, attitudes, and sunburn: in a population with the highest incidence of skin cancer in the world. Cancer Detect Prev, 20(6):566-75 1996.

Summer Sun Exposure - Illinois Teens

Summer Sun Exposure - Illinois teens

Extensive print, radio, and television coverage about the dangers of sun exposure and benefits of sun protection occurred over the past decade.

Teens knew that too much sun was harmful as it caused skin cancer and sunburn. Sunburn was mentioned more often by those with skin types that burned easily and tanned poorly, was better known to girls than to boys, and was recognized more by those with higher socioeconomic status but was not associated with age.
Teenage boys were more likely to obtain occupational sun exposure, and girls sunbathed.

Indoor tanning use was more prevalent among older girls and those with skin types I and II.

Sunscreen use was associated with water recreational activities (swimming, water sports, and going to the beach) by girls slightly more than by boys. Hat-wearing was more common among boys than among girls.

Teen knowledge did not prevent burning. This is particularly troublesome because severe sunburns in youth are associated with an increased risk of melanoma.

Robinson JK et al., Summer sun exposure: knowledge, attitudes, and behaviors of Midwest adolescents. Prev Med, 26(3):364-72 1997 May-Jun.

Sun Sensitivity

Sunburn

Beta-carotene, a quencher of excited species such as singlet oxygen and free radicals, has been reported to protect against cutaneous photodamage, including sunburn acutely and photocarcinogenesis chronically.

Examined the effect of beta-carotene supplementation on the human sunburn response and specifically on the induction of sunburn cells at the time of peak reaction intensity (24 h) after a single solar simulated light exposure 3 times the individually determined minimal "erythema" dose (MED). Administered orally either as a single 120 mg dose to dietarily restricted subjects or for 23 d as a daily 90 mg supplement to subjects on standard diets, beta-carotene increased plasma and skin levels of beta-carotene compared to both pretreatment levels and placebo-treated controls, but provided no clinically or histologically detectable protection against a 3 MED sunburn reaction.

Data suggest that oral beta-carotene supplementation is unlikely to modify the severity of cutaneous photodamage in normal individuals to a clinically meaningful degree.

Garmyn-M: Effect of beta-carotene supplementation on the human sunburn reaction. Exp-Dermatol. 1995 Apr; 4(2): 104-11.

UV Irradiation

UV Irradiation

Examined the effects of ingestion of a single large dose of beta-carotene (120 mg) and UV light exposure on the concentrations of beta-carotene and lycopene in plasma and skin of healthy women.
Ingestion of beta-carotene increased plasma b-carotene concentration by 127%.

A single exposure of a small area of one volar forearm to a dose of solar-simulated light (three times the individually determined minimal erythema dose) resulted in 31 to 46% reductions in skin lycopene concentration compared with an adjacent non-exposed area.

A single 120-mg dose of beta-carotene increases plasma and skin beta-carotene concentrations and has no effect on plasma and skin lycopene concentrations.

When skin is subjected to UV light "stress", more skin lycopene is destroyed compared with beta-carotene, suggesting a role of lycopene in mitigating "oxidative" damage in tissues.

Ribaya-Mercado-JD et al., Skin lycopene is destroyed preferentially over beta-carotene during UV irradiation in humans. J Nutr. 1995, Jul; 125(7): 1854-9.

Vitamin D Status

Vitamin D Status

In the present study the diet and the "nutritional" status of "pregnant" Pakistani immigrant women have been compared with a group of Norwegian women.

The "serum" levels of 25-hydroxyvitamin D3 were significantly lower in the Pakistanis compared with the Norwegians (median 19 nmol/l vs 55 nmol/l) and 83% of the Pakistani women had 25-hydroxyvitamin D3 levels below the reference value (< 30 nmol/l).

Among the Pakistanis a correlation was found between the dietary intake of "margarine", the main source of "vitamin D" in the diet, and the concentration of 25-hydroxyvitamin D3 in serum.

In general, the Pakistanis avoided any direct sunshine exposure, and no relation between outdoor activity and serum level of 25-hydroxyvitamin D3 was found.

Pakistani women living in Oslo are at great risk of developing vitamin D deficiency during "pregnancy" because of: avoidance of sun exposure, a low dietary intake of vitamin D, and no or little use of supplementation.

Henriksen-C et al: Diet and vitamin D status among pregnant Pakistani women in Oslo. Eur-J-Clin-Nutr. 1995 Mar; 49(3): 211-8.

Vitamin E (Sunburn)

Vitamin E

Solar-induced cutaneous damage is mediated partly via oxidative pathways. Some evidence exists for a photoprotective role of "antioxidants".

Healthy human subjects supplemented their usual diet daily with either 400 IU of oral "vitamin E" (alpha-tocopherol acetate) or placebo over a 6-month "period".

Vitamin E levels in plasma increased only modestly and in skin biopsy specimens were unchanged following 1 month and 6 months of supplementation.

No clinical or histologic difference in the response to UVB could be detected between the placebo and vitamin E-supplemented groups. Supplementation did not provide meaningful photoprotection.

Werninghaus-K et al: Evaluation of the photoprotective effect of oral vitamin E supplementation. Arch-Dermatol. 1994 Oct; 130(10): 1257-61.

Zinc (Sunburn)

Zinc

For many years, zinc salts have been used both topically and orally to treat minor burns and abrasions as well as to enhance wound repair in man and animals.

Described the protective effects of zinc against UV-induced genotoxicity in vitro and against sunburn cell formation in mouse skin in vivo.

Inclusion of zinc at 5 micrograms/mL in the medium significantly reduced the frequency of micronuclei and of micronucleated cells. In hairless mice, topical application of zinc chloride for 5 consecutive days, or a single application 2 h prior to UV exposure, reduced the number of sunburn cells in the epidermis as did application of zinc 1 h after exposure.

Application 2 h after irradiation also tended to have a protective effect, although there was a large variation between animals.

An influx of zinc can protect epidermal cells against some of the more delayed effects of UV-induced damage.

Record IR et al., Protection by zinc against UVA- and UVB-induced cellular and genomic damage in vivo and in vitro. Biol Trace Elem Res, 53(1-3):19-25 1996.

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