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Ultraviolet exposure scenarios: risks of erythema from recommendations on cutaneous vitamin D synthesis. - Adv Exp Med Biol. 2008 - SpringerLink - Book Chapter
Ultraviolet exposure scenarios: risks of erythema from recommendations on cutaneous vitamin D synthesis.
Webb AR, Engelsen O.
Adv Exp Med Biol. 2008;624:72-85.
PMID: 18348448
DOI: 10.1007/978-0-387-77574-6_6
Duration of vitamin D synthesis from weather model data for use in prospective epidemiological studies. - Int J Biometeorol. 2009 Sep - SpringerLink - Journal Article
Duration of vitamin D synthesis from weather model data for use in prospective epidemiological studies.
Edvardsen K, Engelsen O, Brustad M.
Int J Biometeorol. 2009 Sep;53(5):451-9. Epub 2009 May 15.
PMID: 19444487
DOI: 10.1007/s00484-009-0231-6
VitD-ez Easy Duration of Vitamin D Synthesis in Human Skin
Vitamin D production in human skin occurs only when UV radiation exceeds a threshold. From simulations of UV irradiances, the VitD-ez www page ( http://zardoz.nilu.no/~olaeng/fastrt/VitD-ez.html) computes the daily duration of dermal vitamin D production at midday when UV radiation exceeds the required threshold. The VitD-ez www page is a simplified version of the more complex VitD web page ( http://zardoz.nilu.no/~olaeng/fastrt/VitD.html). The simplified VitD-ez www page is convenient for users unfamiliar to radiative transfer modelling, because the model input is limited and more intuitive.
Daily duration of vitamin D synthesis in human skin with relation to latitude, total ozone, altitude, ground cover, aerosols and cloud thickness - Photochem Photobiol. 2005 Nov-Dec;81(6):1287-90.
Daily duration of vitamin D synthesis in human skin with relation to latitude, total ozone, altitude, ground cover, aerosols and cloud thickness.
Engelsen O, Brustad M, Aksnes L, Lund E.
Photochem Photobiol. 2005 Nov-Dec;81(6):1287-90.
PMID: 16354110
Vitamin D production in human skin occurs only when incident UV radiation exceeds a certain threshold. From simulations of UV irradiances worldwide and throughout the year, we have studied the dependency of the extent and duration of cutaneous vitamin D production in terms of latitude, time, total ozone, clouds, aerosols, surface reflectivity and altitude. For clear atmospheric conditions, no cutaneous vitamin D production occurs at 51 degrees latitude and higher during some periods of the year. At 70 degrees latitude, vitamin D synthesis can be absent for 5 months. Clouds, aerosols and thick ozone events reduce the duration of vitamin D synthesis considerably, and can suppress vitamin D synthesis completely even at the equator. A web page allowing the computation of the duration of cutaneous vitamin D production worldwide throughout the year, for various atmospheric and surface conditions, is available on the Internet at http://zardoz.nilu.no/~olaeng/fastrt/VitD.html and http://zardoz.nilu.no/~olaeng/fastrt/VitD-ez.html. The computational methodology is outlined here.
Daily duration of vitamin D synthesis in human skin with relation to latitude, total ozone, altitude, ground cover, aerosols and cloud thickness - NILU - Norsk institutt for luftforskning
"Daily duration of vitamin D synthesis in human skin with relation to latitude, total ozone, altitude, ground cover, aerosols and cloud thickness."
Vitamin D effective ultraviolet wavelengths due to scattering in shade - ScienceDirect - The Journal of Steroid Biochemistry and Molecular Biology
Vitamin D effective ultraviolet wavelengths due to scattering in shade.
Turnbull DJ, Parisi AV, Kimlin MG.
J Steroid Biochem Mol Biol. 2005 Sep;96(5):431-6. Epub 2005 Jul 6.
PMID: 16005208
In vivo threshold for cutaneous synthesis of vitamin D3. - [J Lab Clin Med. 1989] - PubMed Result
In vivo threshold for cutaneous synthesis of vitamin D3.
Matsuoka LY, Wortsman J, Haddad JG, Hollis BW.
J Lab Clin Med. 1989 Sep;114(3):301-5.
PMID: 2549141
Regulation of cutaneous previtamin D3 photosynthesis in man: skin pigment is not an essential regulator -- Holick et al. 211 (4482): 590 -- Science
Holick, M. F., MacLaughlin, J. A. & Doppelt, S. H. (1981)
Factors that influence the cutaneous photosynthesis of previtamin D3. Science 211:590-593
When human skin was exposed to simulated solar ultraviolet radiation, epidermal 7-dehydrocholesterol was converted to previtamin D3. During prolonged exposure to simulated solar ultraviolet radiation, the synthesis of previtamin D3 reached a plateau at about 10 to 15 percent of the original 7-dehydrocholesterol content, and previtamin D3 was photoisomerized to two biologically inert isomers, lumisterol3 and tachysterol3. Increases either in skin melanin concentration or in latitude necessitated increases in the exposure time to simulated solar ultraviolet radiation required to maximize the formation, but not the total content, of previtamin D3. In order of importance, the significant determinants limiting the cutaneous production of previtamin D3 are (i) photochemical regulation, (ii) pigmentation, and (iii) latitude.
Aging decreases the capacity of human skin to produce vitamin D3. - Journal of Clinical Investigation
Aging decreases the capacity of human skin to produce vitamin D3.
MacLaughlin J, Holick MF.
J Clin Invest. 1985 Oct;76(4):1536-8.
PMID: 2997282
doi:10.1172/JCI112134
An evaluation of surgically obtained skin (age range, 8-92 yr) revealed that there is an age-dependent decrease in the epidermal concentrations of provitamin D3 (7-dehydrocholesterol). To ascertain that aging indeed decreased the capacity of human skin to produce vitamin D3, some of the skin samples were exposed to ultraviolet radiation and the content of previtamin D3 was determined in the epidermis and dermis. The epidermis in the young and older subjects was the major site for the formation of previtamin D3, accounting for greater than 80% of the total previtamin D3 that was produced in the skin. A comparison of the amount of previtamin D3 produced in the skin from the 8- and 18-yr-old subjects with the amount produced in the skin from the 77- and 82-yr-old subjects revealed that aging can decrease by greater than twofold the capacity of the skin to produce previtamin D3. Recognition of this difference may be extremely important for the elderly, who infrequently expose a small area of skin to sunlight and who depend on this exposure for their vitamin D nutritional needs.
Vitamin D and skin physiology: a D-lightful story - JBMR Online - Journal of Bone and Mineral Research - 22(s2):V28 - Full Text
Vitamin D and skin physiology: a D-lightful story.
Holick MF, Chen TC, Lu Z, Sauter E.
J Bone Miner Res. 2007 Dec;22 Suppl 2:V28-33.
PMID: 18290718
doi: 10.1359/jbmr.07s211
Very few foods naturally contain vitamin D, and those that do have a very variable vitamin D content. Recently it was observed that wild caught salmon had between 75% and 90% more vitamin D(3) compared with farmed salmon. The associations regarding increased risk of common deadly cancers, autoimmune diseases, infectious diseases, and cardiovascular disease with living at higher latitudes and being prone to vitamin D deficiency should alert all health care professionals about the importance of vitamin D for overall health and well being.
Humans have depended on sunlight for their vitamin D requirement. The impact of season, time of day, and latitude on vitamin D synthesis is well documented.(2,3) We now report that altitude also has a dramatic influence on vitamin D3 production and that living at altitudes above 3500 m permits previtamin D3 production at a time when very little is produced at latitudes below 3400 m. It was surprising that, at 27° N in Agra (169 M), little previtamin D3 production was observed. However, there was significant air pollution that caused a haze over the city. It is likely the ozone and other UVB-absorbing pollutants in the air prevented the solar UVB photons from reaching the earth’s surface to produce previtamin D3.
Factors that Influence the Cutaneous Synthesis and Dietary Sources of Vitamin D
Factors that influence the cutaneous synthesis and dietary sources of vitamin D.
Chen TC, Chimeh F, Lu Z, Mathieu J, Person KS, Zhang A, Kohn N, Martinello S, Berkowitz R, Holick MF.
Arch Biochem Biophys. 2007 Apr 15;460(2):213-7. Epub 2007 Jan 8.
PMID: 17254541
doi: 10.1016/j.abb.2006.12.017
Vitamin D is rare in food. Among the vitamin D-rich food, oily fish are considered to be one of the best sources. Therefore, we analyzed the vitamin D content in several commonly consumed oily and non-oily fish. The data showed that farmed salmon had a mean content of vitamin D that was ~25% of the mean content found in wild caught salmon from Alaska, and that vitamin D2 was found in farmed salmon, but not in wild caught salmon. The results provide useful global guidelines for obtaining sufficient vitamin D3 by cutaneous synthesis and from dietary intake to prevent vitamin D deficiency and its health consequences.ensuing illness, especially, bone fractures in the elderly.
Sunlight Regulates the Cutaneous Production of Vitamin D3 by Causing Its Photodegradation -- WEBB et al. 68 (5): 882 -- Journal of Clinical Endocrinology & Metabolism
Sunlight regulates the cutaneous production of vitamin D3 by causing its photodegradation.
Webb AR, DeCosta BR, Holick MF.
J Clin Endocrinol Metab. 1989 May;68(5):882-7.
PMID: 2541158
doi:10.1210/jcem-68-5-882
Vitamin D3 proved to be exquisitely sensitive to sunlight, and once formed in the skin, exposure to sunlight resulted in its rapid photodegradation to a variety of photoproducts, including 5,6-transvitamin D3, suprasterol I, and suprasterol II.suprasterol I, and suprasterol II.
Influence of Season and Latitude on the Cutaneous Synthesis of Vitamin D3: Exposure to Winter Sunlight in Boston and Edmonton Will Not Promote Vitamin D3 Synthesis in Human Skin -- WEBB et al. 67 (2): 373 -- Journal of Clinical Endocrinology & Metabolism
nfluence of season and latitude on the cutaneous synthesis of vitamin D3: exposure to winter sunlight in Boston and Edmonton will not promote vitamin D3 synthesis in human skin.
Webb AR, Kline L, Holick MF.
J Clin Endocrinol Metab. 1988 Aug;67(2):373-8.
PMID: 2839537
doi:10.1210/jcem-67-2-373
These results quantify the dramatic influence of changes in solar UVB radiation on cutaneous vitamin D3 synthesis and indicate the latitudinal increase in the length of the "vitamin D winter" during which dietary supplementation of the vitamin may be advisable.
Aging decreases the capacity of human skin to produce vitamin D3. - J Clin Invest. 1985 Oct;76(4):1536-8.
Aging decreases the capacity of human skin to produce vitamin D3.
MacLaughlin J, Holick MF.
J Clin Invest. 1985 Oct;76(4):1536-8.
PMID: 2997282
White Europeans evolved only ‘5,500 years ago’ - Times Online
White Europeans could have evolved as recently as 5,500 years ago, according to research which suggests that the early humans who populated Britain and Scandinavia had dark skins for millenniums.
It was only when early humans gave up hunter-gathering and switched to farming about 5,500 years ago that white skin began to be favoured, say the researchers.
This is because farmed food was deficient in vitamin D, a vital nutrient. Humans can make this in their skin when exposed to sunlight, but dark skin is much less efficient at it.
Vitamin D (Cholecalciferol, Calcitriol)
Bioactive vitamin D or calcitriol is a steroid hormone that has long been known for its important role in regulating body levels of calcium and phosphorus, and in mineralization of bone. More recently, it has become clear that receptors for vitamin D are present in a wide variety of cells, and that this hormone has biologic effects which extend far beyond control of mineral metabolism.
The active form of vitamin D binds to intracellular receptors that then function as transcription factors to modulate gene expression. Like the receptors for other steroid hormones and thyroid hormones, the vitamin D receptor has hormone-binding and DNA-binding domains. The vitamin D receptor forms a complex with another intracellular receptor, the retinoid-X receptor, and that heterodimer is what binds to DNA. In most cases studied, the effect is to activate transcription, but situations are also known in which vitamin D suppresses transcription.
Each of the forms of vitamin D is hydrophobic, and is transported in blood bound to carrier proteins. The major carrier is called, appropriately, vitamin D-binding protein. The halflife of 25-hydroxycholecalciferol is several weeks, while that of 1,25-dihydroxycholecalciferol is only a few hours.
The vitamin D receptor binds several forms of cholecalciferol. Its affinity for 1,25-dihydroxycholecalciferol is roughly 1000 times that for 25-hydroxycholecalciferol, which explains their relative biological potencies
CYP17 blockade by abiraterone: further evidence for frequent continued hormone-dependence in castration-resistant prostate cancer - British Journal of Cancer - Abstract of article
CYP17 blockade by abiraterone: further evidence for frequent continued hormone-dependence in castration-resistant prostate cancer.
Ang JE, Olmos D, de Bono JS.
Br J Cancer. 2009 Mar 10;100(5):671-5. Epub 2009 Feb 17.
PMID: 19223900
doi:10.1038/sj.bjc.6604904
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