Re: UV blood irradiation mechanism - long, & hard science

[Guest guest]

Hi, ,

>You say UV can't stay in the cells because it's light. That makes some

>sense. It must be changing to another form of energy, right, because it's

>not passing all the way through us (I'm assuming we have UV shadows, which

>I

>think is true)? Visible light, for example, makes things warmer. Other

>materials flouresce (spelling?) when exposed to flourescent light. How does

>that work? Perhaps something similar is going on here. In your knowledge,

>when the proteins are changed, etc., is the same amount of UV

>leaving/passing through the cell as went in? It can't be--because it's

>doing

>some work there. I was flipping through the book this afternoon and noticed

>that at one point it explicitly said estrogen absorbs UV. What does that

>mean that some parts of us absorb more UV than others? You're suggesting

>that " absorption " equals chemical alteration, right?

Yes, some parts absorb more UV than others. Chemicals with an aromatic ring

absorb much more than anything else. That includes DNA, RNA, tryptophan in

proteins (to a lesser extent phenylalanine and tyrosine also), estrogens,

and heme (in hemoglobin) as the most common ones. But since every cell is

loaded with DNA, RNA and proteins, all cells will absorb UV.

When a UV photon is absorbed, it transfers its energy intot he chemical

bonds of whatever molecule absorbed it. That makes that chemical more

reactive. A few things can spit most of the photon's energy back out as

another photon (shorter wavelength, so lower energy) - that is fluorescence.

If there is a big time lag, that is phoshorescence also.

In most cases, though, the energy is trapped in the molecule that absorbed

the photon. This energy can dissipate, as heat, if nothing else happens.

(Same as for absorbtion of visible light.) But more often, the extra energy

makes the molecule so reactive that it reacts with something else that is

handy.

For a DNA base, this is usually another DNA base along the same DNA strand -

that gives T-T dimers, which is the kind of damage that can be repaired by a

specific enzyme (missing in people with xeroderma pigmentosus - they need to

stay out of UV, so no sunlight.) It can also cross-link the two strands,

which requires a cut-and-patch kind of repair, that can lead to mutations.

If the damage is not repaired, the result is usually cell death.

RNA bases can also form these kinds of cross-links and dimers, but since the

RNA is turned over, that damage isusually cleaned up before it can damage

the rest of the cell.

Proteins will sometimes cross-link, and sometimes make a chemical reaction

that breaks the side chain of the protein. Since proteins, also are turning

over, mostly this damage is cleaned up.

The only problem comes from cells that get so much UV that they can't repair

all of the damage - those cells die. If the UV is external, you get a

sunburn from it.

Again, the damage to WBCs from blood irradiation should be at a level that

is not lethal to these cells, but does cause enough damage to induce the

cells to make more repair enzymes.

A few viruses have a genetic mechanism that causes them to go from latent

(inactive) to active when the infected host cell is irradiated with UV. Many

viruses do the same thing when they sense DNA damage such as can result from

UV. So the blood irradiation may be causing virally-infected cells to become

'lytic' - they produce more virus and break open to dump the virus out. If

this free virus induces an antibody or macrophage response, then this

process can cause an immune reaction to kick in and actively fight the

infection, whereas before the virus would be at such low levels in the

blood that it would not cause an immune reaction.

You can see that this is a complicated system. I don't believe that anyone

has a real handle on what all is going on, what is induced in terms of

repair or immune reaction, etc. So I don't believe the people (including

most mainstream doctors and scientists) who say automatically that it can't

have an effect. But I won't do it on myself until there is some more in the

way of clinical studies.

jerry

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