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Pigs can breathe through their butts. Can humans?

关闭桃红色猪卷曲尾巴和背面
(图片信用:Shutterstock)

老鼠,大鼠和猪都分享了一个秘密超级大国:他们都可以使用他们的肠子来呼吸,通过抽氧来发现这种动物的屁股,科学家发现了这一点。

你问为什么跑这样的实验?研究团队希望找到机械通风的潜在替代品,一种医疗机器,机器将空气推入患者lungs通过风向管。呼吸机提供oxygen到肺部并帮助从血液中取出二氧化碳,但机器并不总是可用。

例如,在Covid-19大流行,医院面临严重短缺的呼吸机,纽约时报报道。虽然医生也可以使用一个名为的技术澳门金沙网络娱乐场体外膜氧合(ECMO),其中血液被泵出身体并用机器重新氧化,该过程具有固有的风险,例如出血和血栓;而且它通常比呼吸机不可用,根据梅奥诊所的说法

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为了寻找另一种解决方案,研究作者利用了像海参和淡水鱼一样的水生动动物和淡水鱼(Misgumus anguillicandatus), which use theirintestines呼吸。目前尚不清楚人类和其他哺乳动物是否具有相似的能力,尽管一些科学家试图回答这个问题20世纪50年代and20世纪60年代

“我们最初看着一只小鼠模型系统,看看我们是否可以在Anusly内提供氧气,”东京医疗和牙科大学教授高级作者Takanori博士和干细胞和有机体中心的董事辛辛那提儿童医院医疗中心的研究与医学。

"Every time we performed experiments, we were quite surprised," Takebe told Live Science.

没有肠道通气,miceplaced in a low-oxygen environment survived for only about 11 minutes; with ventilation into their anuses, 75% survived for 50 minutes, thanks to an infusion of oxygen that reached their hearts. The team then tried using oxygenated liquid, rather than gas, in mice, rats andpigs,他们发现了同样有前途的结果。根据他们的研究结果14在期刊上发布的研究结果,仍然需要做更多的工作,以了解这些方法是否在人类中是安全有效的。Med

"The pandemic has highlighted the need to expand options for ventilation and oxygenation in critical illness, and this niche will persist even as the pandemic subsides," as there will be times when mechanical ventilation is unavailable or inadequate on its own, Dr. Caleb Kelly, a clinical fellow and physician-scientist at Yale School of Medicine,在研究的评论中写道。If, after further evaluation, intestinal ventilation eventually becomes common practice in intensive care units, this new study "will be marked by historians as a key scientific contribution," he wrote.

Before starting their experiments in rodents, the team got very familiar with loach guts. The fish take in oxygen mostly through their gills, but occasionally, when exposed to low-oxygen conditions, loaches instead use a portion of their intestines for gas exchange, Takebe said. In fact, in response to the lack of oxygen, the structure of gut tissues near the anus changes such that the density of nearby blood vessels increases and secretion of fluids related to digestion decreases.

These subtle changes allow loaches to "suck up the oxygen more efficiently," Takebe said. In addition, the outermost lining of the loach gut — the epithelium — is very thin, meaning oxygen can easily permeate the tissue to reach the blood vessels beneath, he added. To simulate this structure in their mouse models, the team thinned out the gut epithelium of the rodents using chemicals and various mechanical procedures.

然后将小鼠放置在极低氧气条件下,并用管子将氧气泵送到动物的屁股并进入其大肠。

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与其肠上皮没有稀释的小鼠相比,实验中薄膜上皮的小鼠在显着更长的时间内幸存下来 - 与大约18分钟相比,大多数均存活50分钟。再次,mice没有给任何氧气只幸存下来约11分钟。除了幸存的更长时间外,含有稀疏的肠衬的小组表现出迹象,即它们不再饥饿氧气;他们停止喘着粗气或显示心脏骤停的迹象,并在主要的氧气压力血管改善。

Although this initial experiment suggested that oxygen could pass through the intestine and into循环据说,稀疏肠道上皮可能在人类患者中可能是不可行的。

Particularly in critically ill patients, "I think additional damage to the gut would be really dangerous, for the treatment perspective," Takebe said. But "over the course of the experiments, we realized that even the intact gut has some, not really efficient, but some capacity to exchange the gas," he noted, meaning there may be a way to introduce oxygen through the gut without first thinning out the tissues.

So in another experiment, rather than using oxygen gas, the team tried perfluorodecalin (PFD), a liquid fluorocarbon that can be infused with a large amount of oxygen. The liquid is already used in people, such as for use in the lungs of infants with severe respiratory distress, the authors noted in their report.

关闭老鼠的尾巴和后肢

(图片信用:Shutterstock)

液体还可作为表面活性剂 - 降低表面张力的物质;由于表面活性剂介绍肺的气囊并有助于提高器官中的气体交换,因此PFD可以满足肠道中的类似目的。

Much like in the oxygen-gas experiments, the oxygenated PFD rescued mice from the effects of being placed in a low-oxygen chamber, enabling the rodents to meander about their cage more than mice not given the treatment. After just one injection of 0.03 ounces (1 milliliter) of the liquid, the rodents' improvements persisted for about 60 minutes.

"We are not quite sure why this improvement is persisting much longer than the original expectations," Takebe noted, as the authors expected the effects to wear off in just a couple minutes. "But the observation is really reproducible and very robust."

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然后,该团队搬到了呼吸衰竭的猪模型,在那里他们将猪在呼吸机上放置猪,只提供低水平的氧气,然后用长管注入PDF进入猪后侧。与未给出PFD治疗的猪相比,猪在血液的氧饱和度方面提供了PFD,颜色和温暖恢复到皮肤上。13.5盎司(400毫升)输注持续这些改善约18至19分钟,并且该团队发现它们可以向猪提供额外的剂量而不会产生明显的副作用。

The team also tested the safety of repeat dosing in rats and found that, while their oxygen levels rose, the animals showed no notable side effects, markers of organ damage or stray PFD lingering in their cells.

在这种在动物模型中取得了成功之后,他的团队希望在明年的某个时候开始在人类的临床试验。他说,他们可能会首先在健康志愿者中测试方法的安全性,并开始制定剂量水平是合理的。然而,为了使从动物跳到人类患者,该团队将需要解决一些关键问题。

例如,治疗可能潜在刺激迷走神经 - 一种连接肠道和脑的长神经 - 所以审判组织者可能会在副作用时享受,如血压下降或晕倒。而且,与身体中的其他器官相比,下肠含有相对较少的氧气。他说,肠道内肠道的细菌和病毒的群落适应了这些低氧条件,突然输注氧气可能会破坏这些微生物。

“逆转这种所谓的”生理缺氧“的后果是未知的,”凯莉在评论中注意到,回顾了招草的情绪。他写的,在人类中,重要的是确定可以安全地施入肠道中的含氧液体,而不会导致肠道环境的意外变化。

此外,该研究中的动物模型并不完全反映呼吸衰竭期间患者经历的危重患者的经历,这种病症通常与感染,炎症和低血流,凯利指出。因此,在啮齿动物和猪不相关的患者中可能存在额外的因素需要考虑。此外,根据给定的患者的病情,他们可能需要更高或更低剂量的PFD - 所有这些细节都需要在未来的试验中仔细评估。

Originally published on Live Science.