評論
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So they kind of scratched their heads
他們有些不解
This is one of those studies that evolved
這時研究就要改進了
You do something. You see how it works and you wonder why it didn't and so you do something different and soforth
做實驗，看如何工作，不行就要嘗試其它辦法
So they scratched their heads and then they realize that fetal calf serum in which they were incubating their macrophages is low in the vitamin D metabolites
他們很不解，然后意識到自己在胎牛血清中培育巨噬細胞，這里維生素D代謝物很低
Not much 25D, certainly not much 1,25D
沒有很多25D，也沒很多1,25D
So thinking in the old model that 1,25 was what was important
老模型中 1,25D非常重要
They added 1,25D to the system
他們于是加入1,25D
It got in there to bind with the vitamin D receptor and lo and behold, it worked as what it was supposed to
1,25D同維生素D受體結合，這時，結果就對了
Cathelicidin messenger RNA was expressed and the defense in protein was made and you know all worked just fine
抗菌肽信使RNA得以表達，形成蛋白質防御，一切都很順利
Notice that Cyp24 gene also gets expressed
注意到，這里還表達了Cyp24基因
That's the 24-hydroxylase
這是24-羥化酶
That's the enzyme that chews up 1,25D
是破壞1,25D的酶
So it's no longer active
讓它不再有活性
So it acts just once, rifle shot and then it's done
只活動一次，用完了就完了
but then these guys asked once again and said what is the cell doing expressing the one alpha hydroxylase?
之后他們還問，細胞干什么表達1α-羥化酶
It must have been looking for 25D
必然是在找25D
So they said well, let's add 25D to the system instead of 1,25 and lo and behold, that work perfectly
于是他們加入25D而不是1,25D，結果非常完美
The 1,25D was synthesized into the system and the whole system played itself out
1,25D得以合成，整個系統運作良好
It's absolutely beautiful experiment
非常漂亮的實驗
And in fact, they could do this with circulating levels of 25D
實際上，用循環水平的25D就行了
They're physiological whereas the 1,25 they had to add to the system was higher than you would achieve physiologically
他們加入到系統的1,25D顯然比生理上得到的要高
So clearly, this is how the system was designed to be operating
顯然，這就是系統的工作方式
