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  • ["No one has ever become poor by giving,"Anne Frank.]

  • In 1881, doctor William Halsted rushed to help his sister Minnie, who was hemorrhaging after childbirth.

  • He quickly inserted a needle into his arm, withdrew his own blood, and transferred it to her.

  • After a few uncertain minutes, she began to recover.

  • Halsted didn't know how lucky they'd gotten.

  • His transfusion only worked because he and his sister happened to have the same blood typesomething that isn't guaranteed, even among close relatives.

  • Blood types hadn't been discovered by Halsted's time, though people had been experimenting with transfusions for centuriesmostly unsuccessfully.

  • In 1667, a French physician named Jean-Baptiste Denis became the first to try the technique on a human.

  • Denis transfused sheep's blood into Antoine Mauroy, a man likely suffering from psychosis, in the hopes that it would reduce his symptoms.

  • Afterward, Mauroy was in good spirits.

  • But after a second transfusion, he developed a fever, severe pain in his lower back, intense burning in his arm, and he urinated a thick, black liquid.

  • Though nobody knew it at the time, these were the signs of a dangerous immune response unfolding inside his body.

  • This immune response starts with the production of proteins called antibodies, which distinguish the body's own cells from intruders.

  • They do so by recognizing the foreign proteins, or antigens, embedded in an intruder's cell membrane.

  • Antibodies latch onto the antigens, signaling other immune cells to attack and destroy the foreign cells.

  • The destroyed cells are flushed from the body in urine.

  • In extreme cases, the massive breakdown of cells causes clots in the bloodstream that disrupt the flow of blood to vital organs, overload the kidneys, and cause organ failure.

  • Fortunately, Denis's patient survived the transfusion.

  • But, after other cross-species transfusions proved fatal, the procedure was outlawed across Europe, falling out of favor for several centuries.

  • It wasn't until 1901 that Austrian physician Karl Landsteiner discovered the blood types, the crucial step in the success of human to human blood transfusions.

  • He noticed that when different types were mixed together, they formed clots.

  • This happens when antibodies latch on to cells with foreign antigens, causing blood cells to clump together.

  • But if the donor cells are the same blood type as the recipient's cells, the donor cells won't be flagged for destruction, and won't form clumps.

  • By 1907, doctors were mixing together small amounts of blood before transfusing it.

  • If there were no clumps, the types were a match.

  • This enabled them to save thousands of lives, laying the foundation for modern transfusions.

  • Up to this point, all transfusions had occurred in real time, directly between two individuals.

  • That's because blood begins to clot almost immediately after coming into contact with air—a defense mechanism to prevent excessive blood loss after injury.

  • In 1914, researchers discovered that the chemical sodium citrate stopped blood coagulating by removing the calcium necessary for clot formation.

  • Citrated blood could be stored for later usethe first step in making large scale blood transfusions possible.

  • In 1916, a pair of American scientists found an even more effective anticoagulant called heparin, which works by deactivating enzymes that enable clotting.

  • We still use heparin today.

  • At the same time, American and British researchers developed portable machines that could transport donor blood onto the battlefields of World War I.

  • Combined with the newly-discovered heparin, medics safely stored and preserved liters of blood, wheeling it directly onto the battlefield to transfuse wounded soldiers.

  • After the war, this crude portable box would become the inspiration for the modern-day blood bank, a fixture of hospitals around the world.

  • Did you know that horseshoe crab blood plays an essential role in the medical industry?

  • Find out why we're so dependent on this ancient creature with this video, or continue understanding your circulatory system by learning more about blood types.

["No one has ever become poor by giving,"Anne Frank.]

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C1 US TED-Ed blood denis transfusion donor discovered

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    Mackenzie posted on 2020/05/15
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