金紫昭驴友阿凡提:意想不到的人类精子“杀手”

意想不到的人类精子“杀手”
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常来说，男人每一次心跳平均会产生约1,000个精子。
然而，生活方式的选择、环境因素以及一些偶然事件都能对精子产生破坏：青少年时期遭遇的腹股沟损伤、吸烟、酗酒、剧烈的骑车运动、甚至是直接在膝盖上使用笔记本电脑。
不孕不育的定义是经过一年未采取任何避孕措施的性生活之后仍然无法怀孕。在美国，有六分之一的育龄夫妇受到不孕不育的困扰。纽约长老会医院/威尔康奈尔医学中心(New York Presbyterian/Weill Cornell Medical Center)的生育专家罗森瓦克斯(Zev Rosenwaks)和戈尔茨坦(Marc Goldstein)说，其中四成情况下，问题出在男方，还有四成情况是女方的问题，另外20%则是男女双方都有问题。这两位专家合著有2010年出版的《我们终于有孩子了！》(A Baby at Last!)一书。
戈尔茨坦说，既然不孕症的症结有至少一半情况都在男性身上，那么当夫妻双方在试图弄清楚他们为什么无法怀孕时就应该从简单的精子问题开始着手。
他说，大约70%的男性不育症都是可以治愈的，而在25%左右的情况下，要是能更加清楚地意识到那些有损精子品质的生活方式，这些情况原本是可以避免的。
Getty Images
笔记本放在膝盖上时其所散发的热量会对精子产生影响。
——睾丸素的问题。吸烟、酗酒、吸食大麻、使用可卡因和鸦片类止痛药都会降低产生精子所需要的睾丸素水平，或是减少它们的数量并影响其品质。一些用于治疗高血压、心脏病、胃酸、痛风、肠道炎症、前列腺肥大和脱发的常见处方药也会产生同样的影响。
很多情况下其实是存在替代性药物的，它们不会对患者的生育能力造成损害。
另外，过多的睾丸素反而会降低人体内的睾丸素水平。许多健美运动员都知道，服用睾丸素和其他合成代谢类固醇能够使肌肉强健，但却会使睾丸收缩并停止造精，因为大脑认为体内已有大量的睾丸素，因而停止在体内产生足够多的睾丸素。多数情况下，男性在停止服用这类药品后的几个月之内精子的产生就会恢复正常。
遭受大剂量辐射也会使男性永久丧失生育能力。戈尔茨坦说，无论身体的哪个部位接受X光照射时，男性都应该要求用铅罩护住他们的睾丸。
——保持凉爽。打算“造人”的男性应避免洗澡时水温过高，并且不要穿过紧的裤子，因为睾丸的温度哪怕只是升高几度，精子的产生就会受到影响甚至是停止。纽约州立大学石溪分校(Stony Brook University)的研究表明，将笔记本电脑置于膝盖上将使阴囊内的温度在一小时中升高五华氏度。尽管多数由温度升高引起的问题都只是暂时性的，但研究人员依然强烈建议男性将笔记本电脑放到桌上使用。
不过石溪分校此前进行的一项研究让人们了解到以往的一大认识误区。通过对97名身穿平角或是三角内裤的男子的阴囊温度进行比较，研究人员发现二者之间几乎没有差异。
——外伤。不管是哪一年龄段的男性都应小心谨慎，避免让睾丸遭受外伤，这样可以保护脆弱的导管不会因外伤而断裂，这些导管不仅负责运送精子，还保护它们不受人体免疫系统的侵害，否则免疫系统会将它们视为入侵者而加以攻击。一旦暴露在外，精子便会促成抗精子抗体的形成，这种抗体不仅限制了精子的游动能力，还会阻碍卵子受精。
华盛顿大学(University of Washington)男性生殖医学专家阿莫瑞(John Amory)说，这就是为什么在运动过程中穿上裆部护具是如此重要了，它不仅仅是为了避免疼痛。
——性传播疾病。衣原体、淋病以及其他性传播疾病会通过炎症及疤痕组织阻塞上面提到的这些导管，这些疾病在美国很普遍，35岁的人群中有一半都受到了影响。男性要是遇到小便时有灼烧感或是阴茎有液体流出这样的症状应尽快就医，以便将今后的危害程度降到最低。专家们说，那些有多名性伙伴的人应该使用安全套，并每年接受一次性病检查。
——节食和锻炼。肥胖可以从很多方面影响到男性的生育能力：降低性欲、减少精子数量以及扰乱荷尔蒙平衡。这在某种程度上是因为脂肪组织能够产生雌激素，而这会降低睾丸素的水平。研究表明，保持健康的体重和有节制的饮食能够大大增加怀上健康宝宝的概率。
不过，运动过量可能会破坏男性的生育能力。每周跑步距离超过100英里的男性，其精子数量较少，睾丸素水平也较低。
戈尔茨坦还建议有“造人”计划的男性自行车手每一次只骑行30英里——主要是限制他们穿着紧身短裤的时间。他建议不要用又硬又窄的自行车车座，而要用宽一点的车座。他说，你得让坐骨来承受更多的身体重量。
——环境因素。某些农药、重金属和工业用剂也会减少精子的产量。虽然现在有关双酚A——一种类似雌激素的化合物，某些水瓶和其他塑胶制品中被发现含有此物——的影响人们还了解得不多，但有的生殖专家已让病人远离它们。
与此类似的是，虽然电磁波对人类精子的影响还没有得到深入研究，但戈尔茨坦建议，作为一种预防措施，男性最好还是不要把手机放在他们的前口袋里。
评论内容
2011.07.09 22:07:56
男人，真脆弱
- 巫师
2011.07.09 15:18:31
没房没车，精子有何用武之地
- 无题
2011.07.09 10:08:37
多谢了
- 340660313
2011.07.08 21:18:35
生命在于运动！ 劳动繁衍人类！
- leerq
2011.07.08 12:41:39
2011。07。08 11:20:21
爱护你的球。我们只有两个球。
- goldcannon。com
------------------------
你们真悲剧。。。。
- WSJ20100318
2011.07.08 12:15:44
难得发布一些实用性文章，赞。
- awkk2008
2011.07.08 11:50:21
受益很大，准备下半年开始造人
- marco_hsu
2011.07.08 11:39:06
某些农药、重金属和工业用剂也会减少精子的产量 看到最后傻眼了，其他几条都可避免，这个在天朝……
- ..
2011.07.08 11:20:21
爱护你的球。我们只有两个球。
- goldcannon.com
2011.07.08 10:09:20
好
- 胡育明
2011.07.08 10:05:14
再过一个世纪，人类要想繁殖只有用人工受孕了
- david370203
2011.07.08 09:48:41
很深刻
Surprising Causes Of Male Infertility
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On average, the typical man makes about 1,000 sperm every heartbeat.
Yet a number of lifestyle choices, environmental factors and chance events can sabotage the sperm: an adolescent groin injury, cigarette smoking, heavy drinking, intense cycling and even using a laptop directly on the lap.
Infertility, defined as the inability to conceive after one year of unprotected sex, affects one in six couples of childbearing age in the U.S. In 40% of cases, the problem is with the man; in 40% it's with the woman, and in 20%, something is amiss with both, say Zev Rosenwaks and Marc Goldstein, fertility experts at New York Presbyterian/Weill Cornell Medical Center and co-authors of the 2010 book, 'A Baby at Last!'
Since men contribute to infertility at least half the time, says Dr. Goldstein, couples investigating why they can't conceive should start with a simple sperm count.
About 70% of male infertility is treatable, he says, and in about 25% of cases, it could have been avoided with greater awareness of the lifestyle choices that can harm sperm.
-- Testosterone trouble. Smoking cigarettes, heavy alcohol drinking and using marijuana, cocaine and opioid painkillers can all lower the level of testosterone needed to make sperm or otherwise cut their quantity and quality. So can some commonly prescribed medications for high blood pressure, heart disease, stomach acid, gout, inflammatory bowel disease, enlarged prostates and baldness.
In many cases, alternative drugs exist that don't hamper fertility.
Even extra testosterone can lower a man's testosterone. As many body-builders know, taking testosterone and other anabolic steroids can build muscles but shrink testicles and halt sperm production because the brain thinks the body has plenty and stops making enough of its own. In most cases, normal sperm production resumes within a few months once men stop using the substances.
Exposure to large amounts of radiation can also make men permanently sterile. When getting an X-ray of any part of the body, men should always request a lead shield for their testicles, says Dr. Goldstein.
-- Keeping cool. Men trying to conceive should avoid hot baths, hot tubs and tight pants, since heating the testicles by even a few degrees can hamper or stop sperm production. Studies at Stony Brook University in New York have shown that resting a laptop on the lap can raise temperatures in the scrotum as much as 5 degrees Fahrenheit in an hour. Although most heat problems are temporary, researchers still urge men to use desks or tables instead.
An earlier Stony Brook study debunked one widely held belief, however. In comparing the scrotal temperatures of 97 men wearing either boxers or briefs, researchers found there was little difference.
-- Trauma. Men of all ages should take care to avoid trauma to the testes, in part to avoid rupturing the delicate ducts that carry sperm and keep them shielded from the body's immune system, which would otherwise attack them as foreign invaders. Once exposed, sperm trigger the formation of antisperm antibodies which hamper their ability to swim and fertilize an egg.
'That's why wearing a cup for playing sports is so important,' says John Amory, a specialist in male reproductive medicine at the University of Washington. 'It's not just to prevent pain.'
-- Sexually transmitted diseases. Chlamydia, gonorrhea and other STDs can block those same ducts with inflammation and scar tissue, and they are rampant in the U.S., affecting up to half the population by age 35. Men with symptoms such as burning on urination or discharge from the penis should see a doctor as soon as possible to minimize long-term damage. Those with multiple sex partners should use condoms and be checked yearly for STDs, experts say.
-- Diet and exercise. Obesity can thwart a man's fertility in many ways: lowering libido, reducing sperm counts and disrupting hormone balance. This is in part because fat tissue produces estrogen, which lowers testosterone. Maintaining a healthy weight and diet can significantly increase a man's chance of conceiving a healthy baby, studies show.
Strenuous exercise may hurt fertility, though. Men who run more than 100 miles a week have lower sperm counts and testosterone levels.
Dr. Goldstein also advises male cyclists trying to conceive to ride for only 30 miles at a time -- mainly to limit their time wearing tight bicycle shorts. And he recommends using a seat with a wide back rather than a hard, narrow one. 'You want more of your weight on your sit bones,' he says.
-- Environmental factors. Some pesticides, heavy metals and industrial agents also reduce sperm production. Less is known about the effects of bisphenol A (BPA), an estrogen-like compound found in some water bottles and other plastics, but some fertility experts tell their patients to avoid them.
Similarly, while the effects of electromagnetic waves on human sperm are not well studied, Dr. Goldstein advises men to not to carry their cellphones in their front pockets as a precaution.
Melinda Beck