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衰老之谜 – 译学馆
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衰老之谜

Why do our bodies age? - Monica Menesini

1997年 一名叫雅娜•卡尔芒的法国老太太
In 1997, a French woman named Jeanne Calment
在她122岁164天的那天去世了
passed away after 122 years and 164 days on this Earth,
创造了历史上人类所知的活得最久的记录
making her the oldest known person in history.
她的高寿令人震惊
Her age was so astounding
一名百万富翁甚至出价一百万来寻找可以打破她记录的人
that a millionaire pledged $1 million to anyone who could break her record.
但事实上 能活到这么久或者更久
But in reality, living to this age or beyond
是一项几乎没有人
is a feat that very few, maybe even no humans,
可能完成的壮举
are likely to accomplish.
人类的身体不是为极限衰老而准备的
Human bodies just aren’t built for extreme aging.
我们的极限设定在90岁左右
Our capacity is set at about 90 years.
但衰老到底意味着什么
But what does aging really mean
而我们的机体又是如何与它对抗存活的呢
and how does it counteract the body’s efforts to stay alive?
直观上我们知道它对年龄意味着什么
We know intuitively what it means to age.
对有些人而言 意味着长大
For some, it means growing up,
但对另一些人而言 意味着衰老
while for others, it’s growing old.
但想找到衰老的严格科学定义比较困难
Yet finding a strict scientific definition of aging is a challenge.
我们可以说的是衰老发生在固有的进程
What we can say is that aging occurs when intrinsic processes
以及和外界环境的交互造成了
and interactions with the environment, like sunlight,
身体的分子和细胞的结构和功能
and toxins in the air, water, and our diets,
发生改变时 这些交互包括了阳光
cause changes in the structure
空气 水和我们饮食中的毒素
and function of the body’s molecules and cells.
这些变化反过来又造成了它们的下降
Those changes in turn drive their decline,
随之而来的就是整个机体的衰败
and subsequently, the failure of the whole organism.
人们对衰老的确切机制知之甚少
The exact mechanisms of aging are poorly understood.
但近来 科学家已经确定了九个生理特征
But recently, scientists have identified nine physiological traits,
这些特征包括了从基因变化
ranging from genetic changes
到细胞再生能力的改变
to alterations in a cell’s regenerative ability
而它们都发挥了核心作用
that play a central role.
首先 随着时光的流逝 我们的机体
Firstly, as the years pass, our bodies accumulate genetic damage
以DNA损伤的形式积累了基因损害
in the form of DNA lesions.
它们自然而然地发生在机体DNA复制的时候
These occur naturally when the body’s DNA replicates,
也发生在非分裂细胞中
but also in non-dividing cells.
一种叫线粒体的细胞器特别容易受到这种损伤
Organelles called mitochondria are especially prone to this damage.
线粒体产生三磷酸腺苷
Mitochondria produce adenosine triphosphate,
或者叫ATP
or ATP,
也就是所有细胞进程的主要能量来源
the main energy source for all cellular processes,
此外线粒体能调节很多不同的细胞活动
plus mitochondria regulate many different cell activities
在细胞程序性死亡中起着重要作用【注:细胞程序性死亡是由基因决定的主动有序的死亡方式】
and play an important role in programmed cell death.
如果线粒体功能下降
If mitochondrial function declines,
接着细胞 然后整个器官也会相继恶化
then cells and, later on, whole organs, deteriorate, too.
众所周知 其它变化发生在基因表达模式中
Other changes are known to occur in the expression patterns of genes,
也叫做表观遗传改变
also known as epigenetic alterations,
它们影响了人体的组织和细胞
that affect the body’s tissues and cells.
只新生儿体中有着低水平作用的基因沉默或表达
Genes silenced or expressed only at low levels in newborns
却会在老年人体中有着突出作用
become prominent in older people,
导致退化性疾病的形成
leading to the development of degenerative diseases,
比如阿兹海默症 这些也会加速衰老
like Alzheimer’s, which accelerate aging.
即使我们能够避免所有这些有害的基因改变
Even if we could avoid all these harmful genetic alterations,
甚至连我们自己的细胞都不能拯救我们
not even our own cells could save us.
事实是 细胞的再生
The fact remains that cellular regeneration,
也就是生命之源
the very stuff of life,
也会随着年龄的增长而下降
declines as we age.
我们细胞内的DNA在染色体上
The DNA in our cells is packaged within chromosomes,
每一个都在末端有两个保护区域叫做染色体终端
each of which has two protective regions at the extremities called telomeres.
细胞每复制一次染色体终端就变短一点
Those shorten every time cells replicate.
当染色体终端变得很短时
When telomeres become too short,
细胞停止分裂然后死亡
cells stop replicating and die,
也降低人体更新自身的能力
slowing the body’s ability to renew itself.
随着年龄的增长 细胞也衰老得越来越快
With age, cells increasingly grow senescent, too,
这一进程会在危险时中止细胞周期
a process that halts the cell cycle in times of risk,
比如癌细胞增殖的时候
like when cancer cells are proliferating.
但随着我们年龄增长 这种响应也越频繁地起作用
But the response also kicks in more as we age,
比如中止细胞成长和停止复制的能力
halting cell growth and cutting short their ability to replicate.
衰老还包括干细胞的衰老 它们存在于诸多组织中
Aging also involves stem cells that reside in many tissues
有着无限制补充其它细胞的分化能力
and have the property of dividing without limits to replenish other cells.
随着我们变老 干细胞数量逐渐减少
As we get older, stem cells decrease in number
也逐渐失去再生的潜能
and tend to lose their regenerative potential,
这些会影响我们器官原始功能的组织更新和维护
affecting tissue renewal and maintenance of our organs original functions.
其他变化也围绕着细胞能否正常工作
Other changes revolve around cells’ ability to function properly.
随着衰老的进行 它们不再能够实现蛋白质质量控制
As they age, they stop being able to do quality control on proteins,
造成破坏物和潜在毒素的不断积累
causing the accumulation of damaged and potentially toxic nutrients,
导致过度地新陈代谢 而这些对它们是致命的
leading to excessive metabolic activity that could be fatal for them.
细胞间交流也会放缓
Intercellular communication also slows,
最终毁坏身体的机能
ultimately undermining the body’s functional ability.
关于衰老还有很多的未解之谜
There’s a lot we don’t yet understand about aging.
最后 是否像我们所知的一样 长寿会与饮食
Ultimately, does longer life as we know it come down to diet,
锻炼
exercise,
药物
medicine,
或其它东西相关吗
or something else?
类似于细胞修复纳米机器人
Will future technologies, like cell-repairing nanobots,
或者基因治疗
or gene therapy,
这样的未来科技能延长我们的寿命吗
artificially extend our years?
而我们又是否想要比现在活得更久呢
And do we want to live longer than we already do?
以122岁作为灵感起源
Starting with 122 years as inspiration,
很难说我们的好奇心将止步于何方
there’s no telling where our curiosity might take us.

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