The picture of lung lesions in patients with severe COVID-19 is similar to the manifestation of altitude sickness, so treatment should not correct respiratory failure, but oxygen deficiency, noted Cameron Kyle-Siddel, an intensive care unit doctor in New York. He is quoted by the publication of the Siberian Branch of the Russian Academy of Sciences “First-hand Science”.
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In most patients with coronavirus infection, the level of hemoglobin, a protein that carries oxygen and provides gas exchange in the lungs, drops in the blood, the publication says. At the same time, the level of heme, the non-protein part of hemoglobin, consisting of a complex of porphyrin with iron, a protein of ferritin that binds free iron ions, and biochemical markers of inflammation increase in the blood. According to scientists, this means that the body is actively destroying hemoglobin, causing an inflammatory process.
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A computer model created by Chinese scientists shows that hemoglobin can be attacked not by the virus particles themselves, but by the viral proteins. Some of them bind porphyrin, while others displace iron from the heme, interacting with protein beta chains of hemoglobin. Lung cells respond to changes in gas exchange by increasing inflammation, and the effect is “frosted glass”, which is noticeable on computer tomograms of the lungs of patients, the publication says.
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If this hypothesis is confirmed, the therapeutic effect for patients with antimalarial drugs will become clear. It has already been proven that chloroquine, which kills malaria pathogens living in red blood cells, can prevent the attack of coronavirus proteins on heme. And the antiviral drug favipiravir can not only prevent the virus from entering the cell, but also inhibit the binding of viral proteins to porphyrin, the publication writes.
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Coronavirus resistance in infants under one year of age can be explained by the fact that fetal hemoglobin predominates in their blood, which does not contain beta chains and is probably invulnerable to viral proteins. Hemoglobin without beta chains is also synthesized in patients with thalassemia, a genetic disease common in the “malaria” regions of Africa – in these countries a low incidence of COVID-19 is noted, writes “Science first-hand.”
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Possible scenario for the development of COVID-19
“It all starts with the penetration of coronavirus into cells that carry a“ black mark ”- special surface receptor proteins. Among these cells, there are immune cells that begin to produce antibodies that cause the destruction of red blood cells containing hemoglobin, which is attacked by viral proteins. All this leads to oxygen starvation and impaired gas exchange in the lungs, ”the report said.
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In parallel, inflammation develops in the lung tissue. In severe cases, it, growing like an avalanche, turns into a “cytokine storm” – a systemic reaction that occurs as a result of hyperactivation of the immune system. This leads to the destruction of lung tissue, disturbances in the work of the cardiovascular system, liver, kidneys and even the brain, scientists write.
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Ventilation inefficiency
Doctors note a high, up to 80% mortality rate of patients connected to mechanical ventilation apparatuses, which, especially with prolonged use, can damage lung tissue both due to insufficient moisture in the air mixture and due to the supply of excess air, which leads to tearing or stretching of tissues and accumulation of fluid in the lungs. Since pulmonary disorders in severe patients are similar to the result of altitude sickness, “mechanical ventilation can be used only in a certain mode, or even replaced with the supply of oxygen-enriched air through a breathing mask,” the publication says.
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Scientists admit that antihistamines, corticosteroids, drugs for suppressing an excessive immune response (immunosuppressants), as well as blood transfusion, which helps to compensate for oxygen starvation of tissues, can help avoid serious complications.
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Three types of coronavirus SARS-CoV-2
Now scientists have identified three main variants of the new coronavirus – A, B and C, the publication says. Type B is characteristic of East Asia, primarily for mainland China, and scientists consider type C to be the main one for Europe. The strains circulating in Russia have not yet been recognized.
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“It is possible that all these strains are immunologically or ecologically adapted to the local population and environmental conditions, but how these genetic differences affect the clinical manifestations and the pathophysiological mechanism of the disease is still unknown,” the publication says. “It is also not yet known how this genetic variation affects the clinical manifestations and the pathophysiological mechanism of the disease.”
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There is little hope for the vaccine
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The high mutation rate of the virus does not allow hope for an early vaccine, the newspaper writes. It emphasizes that now there is no exact data regarding the formation of immunity to this disease and the possibility of re-infection. Novosibirsk virologist Sergei Netesov, quoted by First-hand Science, admits a small chance that there is an antigenic cross between the two “usual” for us coronaviruses that cause SARS and SARS-CoV-2, and nonspecific immunity that has already been developed can play a positive role, allowing, if not to prevent infection, at least to alleviate the course of the disease.