Where there is life, there is death. Death is a mysterious and taboo topic that fascinates us all the time, but we all have different views, which are mainly related to one’s cultural and religious background. According to Catholic tradition, people pay homage to the dead on November 2. In France and other European countries, it is customary for people to lay flowers at cemeteries, and they sometimes light a candle at home in memory of a loved one. In Guatemala and other Latin American countries, festivals honoring the dead are lively, with street bands even playing as people make their way to cemeteries.
People interpret the concept of “death” based on the relationship between life and death. Larousse’s Dictionary defines death as “the loss of signs of life of a living organism (organ, individual, tissue, cell) and termination of life.” In other words, the end of life is death. “We can certainly think of the end of life as death, but how do we define life?” asks Neuroscientist Benjamin Roo of the Sorbonne University. Do you have to be conscious to be alive? Or is there brain activity? Have a heart? To define death is essentially to define life, but we end up in an ideological dead end. That is why it is necessary to have a legal definition of death.”
| | “death” of the concept of change
The idea that death meant the loss of vital signs — the heart stopping and breathing — persisted until the early 1950s. In 1952, Bjorn Ibsen, a Danish doctor, took a big step forward in medicine when he invented the ventilator, paving the way for the intensive care unit. His invention also changed the way people think about death, and disputes over the definition of death have persisted ever since. In 1959, French doctors Maurice Gurung and Pierre Morale came up with the concept of a “deep coma,” or brain death. In 1968, an AD hoc committee of Harvard Medical School further explained the concept. Since then, brain death has replaced cardiac arrest as the new standard of individual death.
Many countries have adopted this standard. In 1968, France legalized brain death. In 2012, the World Health Organization defined death as “a permanent loss of consciousness and the loss of all function of the brain stem.” Brain death has long been contested in Japan, where traditional wisdom holds that death is only when the heart stops beating. It wasn’t until 1997 that Japan officially recognized brain death as the end of life, and Japanese attitudes began to change, but the Japanese medical community, influenced by Shinto, still opposes organ transplants.
| | declared dead process of law
The French public health law has a detail on how to define a dead strict regulation: a person shows no sign of the heart beating and breathing for a long time, and the medical appraisement, completely unconscious, complete loss of motor function, no brain stem reflex (for example the pupil) did not respond to light, can be defined as death. Steven Laureys, a neuroscientist at the University of Liege in Belgium, leads a team of researchers who study comas. “When a patient dies,” he wrote in his book “The Great Brain,” “there are two things that happen. One is when the heart and lungs irreversibly stop working, which most people eventually do, and the other is when the brain stops working.”
“The next step for a person without a heartbeat or breathing is to make sure they have any residual feeling. They do things like press on the sternum or nail bed to see if they feel pain. Doctors also determine whether the person still has brainstem reflexes, either by stimulating the cornea with a drop of saline or shining a bright light on the retina. It only takes a few minutes to double check.” After a person’s brain stops working, it is necessary to determine whether it is irreversible. There are two detection methods: one is to do two eeg observations, 30 minutes at a time, 4 hours between, the waveform of both results are flat, indicating irreversible; Another kind is to do cerebral angiography, if the result is cerebral circulation stops, namely the interruption of cerebral blood supply, the explanation is irreversible. A death certificate is signed after a doctor has thus confirmed brain death.
Death is not strictly an “off button” because there are remnants of vital signs, such as hair, skin and nails, that continue to grow for hours after death. Regis Aubrey, a researcher at the Sanson Regional Hospital Centre, said: “We can safely say that people do not die all at once. Each organ stops working at different times.” After a person has no heartbeat, brain activity will continue for more than ten minutes.
Jans Delaire, a neuroscientist at The Charite Medical School in Berlin, delved into this process and published his findings in the March 2018 annals of Neurology. He placed electrodes inside subjects’ skulls and tracked their electrical activity. “We recorded the final moments of the lives of nine patients with the consent of their families,” Delair explained. They tend to have major diseases like brain tumors, and when they go into cardiac arrest, their body automatically goes into energy saving mode due to lack of oxygen.” Nerve cells can survive for a while on the oxygen they have left in the body, during which time they remain intact. After two to five minutes, however, the oxygen runs out and the nerve cells stop releasing nerve impulses and start releasing potassium ions and glutamate, a harmful biochemical reaction that triggers a wave of widespread depolarization that leads to death.
Domino | | death
In a matter of minutes, a wave of depolarization can ripple through the brain, but can we stop the disaster? “Depolarization is reversible if you can solve the oxygen supply problem quickly, but after a certain point, it becomes irreversible.” Delair explains. James ferrer, a biologist at the Stanford university school of medicine in August 2018 in the journal science, published an article puts forward a stroke (cell receives a signal, begin the process of self-destruction) of diffusion and wave are similar, he also compared the process to “the death of dominoes” and “wave” of the pitch.
People tend to release signals before they die, mainly to ease the pain of their own death.
Another team set their sights on caenorhabditis elegans, which is only a millimeter long. “My idea was to go back to the very basics of life and look closely at what actually happens before death,” explains Biologist Alexander Benedetto of Lancaster University, who was part of the team. With funding from the Wellcome Trust, the team successfully completed a project and published it in Cell Letters in August 2018, with Benedetto as co-author.
Benedetto used ultraviolet light and a microscope to observe the death of the nematodes, a process clearly shown in waves of blue fluorescence. “Blue fluorescence irreversibly diffuses from the foregut to the rectum at a rate of 40 microns per second,” he wrote. The biochemical reaction is overwhelming, and death spreads rapidly from one cell to its neighbors in the form of calcification.” During the experiment, the researchers exposed the nematodes to a chemical that killed them in 15 to 20 minutes, videotaped changes in fluorescence and the activity of muscle and nerve cells.
Wave | | delaying death
Benedetto and other researchers are now investigating the hypothesis that the blue death wave could be delayed by finding the corresponding gene in the nervous system and inactivating it. Benedetto said: “We want to buy more minutes for the transplant and give a glimmer of hope to patients waiting for healthy organs.” The exact time of death is still a mystery, and it’s a mystery of great significance, especially for religions, because death has a unique meaning in every religion.
A 2016 study by a team led by Peter Noble of the University of Washington found that the vast majority of genes die when an organism dies, with the exception of a dozen genes in zebrafish and two dozen in mice that remain active for up to 48 hours after an individual dies. The team obtained this information by measuring the amount of messenger RNA. So-called messenger RNA is an intermediary that copies the genetic information in DNA and guides protein synthesis. Next, they will try to track messenger RNA in humans and, if successful, hope to apply the results to organ donation. In addition, MRNA can also help people know the time of death, which can provide no small help for forensic reconstruction of the scene of death.
Researchers at Yale University studied nerve cell activity in the hours after the death of more than 30 pigs. Writing in the journal Nature, they said: “The decay of nerve cells after cessation of blood circulation is a relatively long process, not instantaneous.” But they repeatedly stressed: “There was no sign of any electrical activity in the brain, suggesting they had no sensation and no sensation.” In addition, the ecg waveform is flat, which is also proof of no consciousness. But Pierre Ledow, head of the Sensation and memory team at the Pasteur Institute, said: “Yes, this study is far from proving that we can bring back dead brains, but it does call into question the morality of organ donation.”
All of this is the process of dying, but it’s also worth studying the near-death period that precedes death. Michel Soussan, head of hospice care at The Putier Salbetriere Hospital, said: “There are signals that people give at the end of their lives to ease the pain of dying.” Doctors have also found that when people are dying, they sometimes reminisce about birthdays or weddings and then die peacefully. Marie Fermonweiler, head of palliative care at the Medical Teaching and Medical Centre in Liege, said: “In the final moments of life, patients with severe illnesses are often very calm. It’s as if they’ve been helped by nature and suddenly know how to let go and find peace.” Aubrey concluded: “The final moments of life are often relatively peaceful, as the dying person is able to mobilize his or her emotional and spiritual strength to pass away peacefully.”
