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  • Recently I made a video about what the world looks like in the ultraviolet

  • Some things look the same but generally it's hazier

  • sometimes light and dark are flipped

  • skin looks blotchier and fake teeth stand out

  • Whoa!

  • Smile for me

  • Oh my goodness

  • Are my teeth black?

  • Do you have a fake tooth baby?

  • --Yes --Which one?

  • but the idea for this video started a long time ago with a question I had which is,

  • How does non ionizing radiation like ultraviolet light

  • like ultraviolet light damage skin and lead to cancer?

  • I do like to tell people that if you want to see how good your skin could look,

  • look at your butt

  • because that's an area that doesn't get sun

  • and even old people have perfect butts

  • it's how your skin would age without the sun

  • when I thought about what UV light must be doing to our cells and our DNA,

  • I imagined it would be getting in there and breaking all these bonds and that would be the problem

  • but in fact it's kinda the opposite

  • UV actually facilitates the formation of covalent bonds in our DNA that shouldn't be there.

  • It comes in and it kind of creates these unauthorized bonds between the bases

  • called pyrimidine dimers

  • instead of having them bonded across it bonds the one next to each other

  • if that makes sense. -- Oh. -- Yeah.

  • so what happens is two thymines, which are side be side,

  • can actually get covalently bonded together

  • and that creates a lesion on the DNA you can think of it like a little bump

  • that makes the DNA hard to read and work with

  • That's not enough in itself to cause skin cancer. If that were the case we would just be covered in skin cancers

  • then the next step is that we have to repair it

  • and in the repair,

  • that's when you form mutations that could eventually lead to cancer through a bunch of different pathways

  • and there's actually people who have specific

  • genetic issues that they can't repair these issues and they are covered in skin cancer

  • UV has other effects on the body like

  • suppresses the immune system so, as Haley says, it's a "double whammy"

  • There's also kind of a double whammy because UV not only induces these unauthorized bonds

  • it actually tamps down our natural immune system

  • so one of the best ways we fight cancer is through our immune system

  • we have constantly need surveillance through our skin

  • so not only is sunlight creating these problems,

  • It's actually reducing our ability to fix them.

  • So unfair

  • UV light also causes us to visibly age. It's called photo-aging

  • I should clear up a misconception here that I had which was, I thought glass blocks all ultra-violet light.

  • so I thought if you're inside a car, for example, you really don't need to put on sunscreen because,

  • you're not being exposed to UV light

  • The car does not block UVA. It's glass

  • It does block most UVB

  • but you're still susceptible to those sunspots and those wrinkles through the glass

  • and a lot of my patients if you look and you compare their hands,

  • the left is is more wrinkled or has more sunspots on it because they're driving.

  • So they're sticking that hand... --Sticking that hand out their truckers. Absolutely you can see it the worst

  • And there's a really famous picture of someone whose left side of their face

  • is significantly more, as we'll call photo-aged, or old-looking, than the other side of their face.

  • So that's mostly UVA and UVA, as I said, it's a longer wavelength, penetrates a little bit deeper.

  • so wrinkles mostly come from destruction of our collagen and elastin

  • which is natural fibers that hold up the scaffolding of our skin

  • so with age the cells that secrete collagen

  • they're called fibroblasts they stop producing as much

  • and what the Sun does is it breaks down the existing collagen and elastin we have

  • so fibroblasts really like to be stretched, they like to be pulled and collagen does that, that collagen matrix

  • so the Sun damages the collagen fibers leading to less stretch on fibroblasts

  • and less production of collagen

  • which means that you look a little more saggy

  • I know it's very depressing so sun protection helps the degradation of those collagen and elastin fibers

  • You know there are a lot of creams on the market that claim to be anti-aging

  • but the one that really works

  • is sunscreen

  • preventing ultraviolet light from hitting your skin is the best thing you can do

  • to avoid skin cancer and to avoid photo aging

  • So yeah. It's good advice. Use sunscreen.

  • hey I'm on set for Jurassic world fallen

  • Kingdom and I'm here filming sci-fi test

  • lab where we try to recreate some

  • dinosaur parts out of machinery and test

  • them out so if you want to see that then

  • click here

Recently I made a video about what the world looks like in the ultraviolet


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B1 中級

紫外線がガンや老化の原因になる方法 (How UV Causes Cancer and Aging)

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    林宜悉 に公開 2021 年 01 月 14 日