※ 引述《wizardfizban (瘋法師)》之銘言：
: 1.媒體來源:
: Heho健康
: 2.記者署名:
: 林 以璿
: 3.完整新聞標題:
: COVID 19／康復者復陽、惡化原因找到了？研究：新冠病毒可藏匿於大腦
: 4.完整新聞內文:
: 新冠康復者的後續問題引人關注，不只是這些人可能會出現無法恢復的副作用，甚至在全
: 球範圍內都有案例復發的問題。近日研究指出，新冠病毒在動物實驗中可以藏匿於大腦，
: 成為復發的線索之一。
: 大腦是人類的中央處理器，而COVID-19可引起人類神經系統疾病。近日，《Viruses》發
: 表了研究，發現新冠鼻內感染的小鼠會引起嚴重的神經系統疾病。
: 鼻腔通往大腦的路徑比嘴巴更直接，且嗅覺和味覺的改變是COVID-19的症狀之一。因此，
: 研究人員在小鼠鼻腔內接種病毒細胞和PBS，感染的小鼠在第4天開始體重明顯減輕，並伴
: 有嗜睡、動作緩慢、共濟失調、呼吸困難等併發症，第6天小鼠全部死亡。
: 隨後研究人員展開分析，發現，在小鼠肺部和鼻腔的病毒量於第3天達到峰值，在第5天和
: 第6天逐漸下降，而大腦中的病毒在第3天才被檢測到，於第5天達到較高巔峰，且腦中的
: 最高病毒滴度比肺中的最高滴度高約1000倍，表明新冠在腦中具有很高的複製潛力。
: 在小鼠感染病毒的第6天，研究人員從大腦包括皮質、小腦和海馬迴的部位檢測到了與細
: 胞相關的病毒抗原，小鼠的神經元縮小並出現退化現象，血管周圍出血，白血球浸潤增強
: 。這一發現恰好解釋了為何某些COVID-19患者的肺功能已經得到改善，但卻有可能迅速復
: 發並死亡。
: 由於大腦中不存在免疫反應，因此變成了病毒最喜歡藏身之地。儘管COVID-19康復患者似
: 乎已經逃離魔掌，但依舊可能面臨包括自身免疫性疾病、帕金森氏病、多發性硬化症和一
: 般性認知能力下降等健康問題。
: 參考資料：Neuroinvasion and Encephalitis Following Intranasal Inoculation of
: SARS-CoV-2 in K18-hACE2 Mice
: 文/林以璿 圖/林以璿
: 5.完整新聞連結 (或短網址):
: https://heho.com.tw/archives/159394
: 6.備註:
: 所以會躲在腦部的意思。
https://reurl.cc/E2nxd0
這似乎是美國衛生研究院NIH某位研究員的BLOG
資訊還蠻新的
Taking a Closer Look at COVID-19’s Effects on the Brain
Posted on January 14th, 2021 by Dr. Francis Collins
While primarily a respiratory disease, COVID-19 can also lead to neurological
problems. The first of these symptoms might be the loss of smell and taste,
while some people also may later battle headaches, debilitating fatigue, and
trouble thinking clearly, sometimes referred to as “brain fog.” All of
these symptoms have researchers wondering how exactly the coronavirus that
causes COVID-19, SARS-CoV-2, affects the human brain.
In search of clues, researchers at NIH’s National Institute of Neurological
Disorders and Stroke (NINDS) have now conducted the first in-depth
examinations of human brain tissue samples from people who died after
contracting COVID-19. Their findings, published in the New England Journal of
Medicine, suggest that COVID-19’s many neurological symptoms are likely
explained by the body’s widespread inflammatory response to infection and
associated blood vessel injury—not by infection of the brain tissue itself
[1].
The NIH team, led by Avindra Nath, used a high-powered magnetic resonance
imaging (MRI) scanner (up to 10 times as sensitive as a typical MRI) to
examine postmortem brain tissue from 19 patients. They ranged in age from 5
to 73, and some had preexisting conditions, such as diabetes, obesity, and
cardiovascular disease.
The team focused on the brain’s olfactory bulb that controls our ability to
smell and the brainstem, which regulates breathing and heart rate. Based on
earlier evidence, both areas are thought to be highly susceptible to COVID-19.
Indeed, the MRI images revealed in both regions an unusual number of bright
spots, a sign of inflammation. They also showed dark spots, which indicate
bleeding. A closer look at the bright spots showed that tiny blood vessels in
those areas were thinner than normal and, in some cases, leaked blood
proteins into the brain. This leakage appeared to trigger an immune reaction
that included T cells from the blood and the brain’s scavenging microglia.
The dark spots showed a different pattern, with leaky vessels and clots but
no evidence of an immune reaction.
While those findings are certainly interesting, perhaps equally noteworthy is
what Nath and colleagues didn’t see in those samples. They could find no
evidence in the brain tissue samples that SARS-CoV-2 had invaded the brain
tissue. In fact, several methods to detect genetic material or proteins from
the virus all turned up empty.
The findings are especially intriguing because there has been some suggestion
based on studies in mice that SARS-CoV-2 might cross the blood-brain barrier
and invade the brain. Indeed, a recent report by NIH-funded researchers in
Nature Neuroscience showed that the viral spike protein, when injected into
mice, readily entered the brain along with many other organs [2].
Another recent report in the Journal of Experimental Medicine, which used
mouse and human brain tissue, suggests that SARS-CoV-2 may indeed directly
infect the central nervous system, including the brain [3]. In autopsies of
three people who died from complications of COVID-19, the NIH-supported
researchers detected signs of SARS-CoV-2 in neurons in the brain’s cerebral
cortex. This work was done using the microscopy-based technique of
immunohistochemistry, which uses antibodies to bind to a target, in this
case, the virus’s spike protein. Also last month, in a study published in
the journal Neurobiology of Disease, another NIH-supported team demonstrated
in a series of experiments in cell culture that the SARS-CoV-2 spike protein
could cross a 3D model of the blood-brain barrier and infect the endothelial
cells that line blood vessels in the brain [4].
Clearly, more research is needed, and Nath and colleagues continue to explore
how COVID-19 affects the brain and triggers the neurological symptoms often
seen in people with COVID-19. As we learn more about the many ways COVID-19
wreaks havoc on the body, understanding the neurological symptoms will be
critical in helping people, including the so-called Long Haulers bounce back
from this terrible viral infection.
簡單說
1.COVID確實會對病患帶來神經系統症狀 brain fog
2.神經系統症狀原因比較傾向炎症反應導致而非腦組織被感染，即神經元感染受損導致
3.透過MRI發現大腦嗅球與腦幹有發炎與出血跡象，但在腦組織中
檢測不到病毒的核酸與蛋白質
4.有小鼠研究發現病毒刺突蛋白穿過血腦屏障
5.NIH研究員在屍檢研究中，用顯微鏡在大腦皮質神經元中觀察到COVID的體徵
這是用抗體結合刺突蛋白的化驗技術
6.NIH的細胞培養實驗中，發現刺突蛋白可穿透血腦屏障併感染大腦血管中的內皮細胞
心得
病毒可能穿透血腦屏障併感染大腦血管上的細胞甚至是神經元
不過究竟大腦神經元是否會被病毒感染受直接影響
即是否為神經系統症狀 brain fog 的原因之一則還需要更進一步的研究