Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: ozone layer

Sortuj według:

Ogranicz wyniki do:

Ecological replacements of ozone-depleting substances

100%

Wachowski L., Kirszensztejn P., Foltynowicz Z.

Polish Journal of Environmental Studies

2001

tom 10

nr 6

Abstract: Halogenated aliphatic hydrocarbons have appeared in the natural environment in steadily increasing amounts over several decades as a consequence of their growing use, chiefly as refrigerant, foam blowing agent and solvent, prompted by their unique properties and low cost. It is recognised that anthropogenic emissions of the above compounds, which are referred to as ozone-depleting substances (ODS's), are partly responsible for depletion of the stratospheric ozone layer and the so-called greenhouse effect. The photo decomposition of halogenomethanes in the stratosphere produces significant amounts of chlorine atoms, leading to the decay of atmospheric ozone, which allows increased levels of biologically damaging UV radiation to reach the Earth's surface. The discovery of the above phenomenon has initiated efforts towards the withdrawal of ODS. Nowadays, it is accepted that fully halogenated chlorofluorocarbons (CFC's) are the main source of the chlorine that is eroding Earth's protecting ozone, and their role is of great Global concern. In spite of the fact production CFCs has been banned since 01.01.1995 and their use prohibited since 01.01.1996, the depletion of stratospheric ozone will continue because large amounts of these class compounds are still in use. Therefore, the recovery and subsequent destruction of the CFCs still in use is a logical next step, in particular the conversion of the CFC's into useful products is a challenging task. At present CFCs are being replaced by hydrochlorofluorocarbons (HCFC's) and in perspective by hydrofluorocarbons (HFC's), before better replacements are found. The environmental impact of CFC replacements is considered in terms of their ozone depletion potential (ODP), global warming potential (GWP) and ability to form noxious degradation products.

Chemopreventive effects of Calluna vulgaris and Vitis vinifera extracts on UVB-induced skin damage in SKH-1 hairless mice

58%

Filip A., Clichici S., Daicoviciu D., Catoi C., Bolfa P., Postescu I. D., Gal A., Baldea I., Gherman C., Muresan A.

Journal of Physiology and Pharmacology

2011

tom 62

nr 3

Solar ultraviolet radiation (UV) is a major cause of non-melanoma skin cancer in humans. Photochemoprevention with natural products represents a simple but very effective strategy in the management of cutaneous neoplasia. The study investigated the protective activity of Calluna vulgaris (Cv) and red grape seeds (Vitis vinifera L, Burgund Mare variety) (BM) extracts in vivo on UVB-induced deleterious effects in SKH-1 mice skin. Forty SKH-1 mice were randomly divided into 4 groups (n=10): control, UVB irradiated, Cv + UVB irradiated, BM+UVB irradiated. Both extracts were applied topically on the skin in a dose of 4 mg/40 µl/cm2 before UVB exposure - single dose. The effects were evaluated in skin 24 hours after irradiation through the presence of cyclobutane pyrimidine dimers (CPDs) and sunburn cells, tumor necrosis factor-alpha (TNF-), interleukin (IL)-6 levels. The antioxidant activity of BM extract was higher than those of Cv extract as determined using stable free radical DPPH assay and ABTS test. One single dose of UVB generated formation of CPDs (p<0.0001) and sunburn cells (p<0.0002) and increased the cytokine levels in skin (p<0.0001). Twenty hours following irradiation BM extract inhibited UVB-induced sunburn cells (p<0.02) and CPDs formation (p<0.0001). Pretreatment with Cv and BM extracts resulted in significantly reduced levels of IL-6 and TNF- compared with UVB alone (p<0.0001). Our results suggest that BM extracts might be a potential candidate in preventing the damages induced by UV in skin.

Ograniczanie wyników

1 Journal of Physiology and Pharmacology

1 Polish Journal of Environmental Studies

1 Baldea I.

1 Bolfa P.

1 Catoi C.

1 Clichici S.

1 Daicoviciu D.

1 Filip A.

1 Foltynowicz Z.

1 Gal A.

1 Gherman C.

1 Kirszensztejn P.

1 Muresan A.

1 Postescu I. D.

1 Wachowski L.

1 2011

1 2001

Wyniki wyszukiwania

Ecological replacements of ozone-depleting substances

Chemopreventive effects of Calluna vulgaris and Vitis vinifera extracts on UVB-induced skin damage in SKH-1 hairless mice