Skin type differences in solar-simulated radiation-induced oxidative stress.

BACKGROUND: Human skin protects the body from external damage, pathogens and oxidative stress factors such as ultraviolet (UV) radiation. Excessive exposure to UV radiation can lead to increased production of free radicals and hence to skin damage such as inflammation, premature skin ageing and skin cancer. Besides UV, the visible and near infrared (NIR) regions are also a source of radical production. Half of all free radicals are induced by the visible + NIR region of the solar spectrum in people with skin types I-III, but data on the effects in people with skin types IV-VI are missing. OBJECTIVES: This in vivo pilot study addressed the distribution of radical production in skin types IV and V during irradiation in the UV, visible and NIR spectral regions, comparing the first results with those of skin type II. METHODS: The measurements were performed in vivo using L-band electron paramagnetic resonance spectroscopy and the spin probe PCA. RESULTS: In skin types IV-V most radicals were induced in the visible + NIR region, followed by the NIR and UV regions of the sun spectrum. Significantly (P ≤ 0·05) more radicals were induced in skin types IV-V than in type II during NIR irradiation, whereas skin types IV-V exhibited significantly less UV-induced radicals (P ≤ 0·01) than skin type II. CONCLUSIONS: All spectral regions (UV, visible and NIR) cause free radical formation in skin types II and IV-V. After 4 min of solar-simulated exposure (UV-NIR), the radical formation in skin types IV-V is 60% of that in skin type II. Therefore people with darker skin types also need solar protection.

Composition and use of puppy milk replacers in German Shepherd puppies in the Netherlands.

Enostosis or eosinophilic panosteitis is a common disease in young growing large-breed dogs, such as the German Shepherd, and the risk of developing the disease by 3-4 months of age is increased by a high calcium intake. The aim of the study was to investigate whether German Shepherd puppies raised on milk replacers receive more calcium and/or vitamin D than their requirements in the pre-weaning period and thus are at increased risk of developing skeletal diseases. To this end, we surveyed German Shepherd breeders in the Netherlands about the use of puppy milk replacers (PMR). The metabolizable energy, calcium, phosphorus and vitamin D content of the eight most used PMR were compared with that of bitch milk, as reported in the literature. The protein and fat content of most PMR were somewhat lower (range 24.4-33.2 g per 100 g on dmb and 18.3-37.5 g per 100 g on dmb respectively) compared with bitch milk (31.9 and 40.2 g on dmb respectively). The vitamin D content of one of the PMR samples was sevenfold the level recommended by the NRC (Nutrient Requirements of Dogs and Cats, National Academy Press, 2006) and threefold the average level of bitch milk. The clinical relevance of this high amount is questionable, as bitch milk contains mainly 25-hydroxy-vitamin D [3843 µg (96.1 IU) per 100 g on dmb] and only limited amounts of vitamin D [524 µg (13.3 IU) per 100 g on dmb], as was determined in this study. Dutch German Shepherd breeders tended to overfeed their puppies. We calculated that misguided use of PMR can increase the risk of excessive calcium, phosphorus and possibly vitamin D intake during a vulnerable period, potentially giving rise to bone and cartilage problems later in life.