Posts Tagged ‘germ theory’
“It is not the germs we need worry about. It is our inner terrain.”*…
Background becomes foreground: Jean-Laurent Casanova on how we might better think about infectious diseases…
In 1955, René Dubos famously expressed his “second thoughts on the germ theory”, attributing infectious diseases to various “changing circumstances” that weaken the host by unknown mechanisms. He rightly stressed that only a small minority of individuals infected by almost any microbe develop clinical disease. Intriguingly, though, he did not mention the abundant and elegant findings reported from 1905 onward that unambiguously pointed to host genetic determinants of infection outcome in plants and animals, including human inborn errors of immunity. Diverse findings over the next 50 y[ears] corroborated and extended these earlier genetic and immunological observations that René Dubos had neglected. Meanwhile, the sequential advent of immunosuppression- and HIV–driven immunodeficiencies unexpectedly provided a mechanistic basis for his own views. Collectively, these two lines of evidence support a host theory of infectious diseases, with inherited and acquired immunodeficiencies as the key determinants of severe infection outcome, relegating the germ to an environmental trigger that reveals an underlying and preexisting cause of disease and death…
The full essay: “From second thoughts on the germ theory to a full-blown host theory,” from @PNASNews.
Pair with: “The World Is Toxic. Welcome to the Metabolic Era,” from @k_pendergrast in @WIRED.
* Louis Pasteur (who was clearly already having second thoughts)
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As we contemplate the clinical, we might sending healing birthday greetings to Charles Mayo; he was born on this date in 1865. A medical doctor (surgeon) and philanthropist, he co-founded the Mayo Clinic and it’s supporting/governing body, the Mayo Foundation. Within Mayo’s lifetime, it registered one million patients. As of today, Mayo Clinic has ranked number one in the United States for seven consecutive years in U.S. News & World Report‘s Best Hospitals Honor Roll, maintaining a position at or near the top for more than 35 years.
“Look deep into nature, and then you will understand everything better”*…
Philip Ball unpacks the geometric rules that define eyes, honeycombs, and soap bubbles…
How do bees do it? The honeycombs in which they store their amber nectar are marvels of precision engineering, an array of prism-shaped cells with a perfectly hexagonal cross-section. The wax walls are made with a very precise thickness, the cells are gently tilted from the horizontal to prevent the viscous honey from running out, and the entire comb is aligned with the Earth’s magnetic field. Yet this structure is made without any blueprint or foresight, by many bees working simultaneously and somehow coordinating their efforts to avoid mismatched cells.
The ancient Greek philosopher Pappus of Alexandria thought that the bees must be endowed with “a certain geometrical forethought.” And who could have given them this wisdom, but God? According to William Kirby in 1852, bees are “Heaven-instructed mathematicians.” Charles Darwin wasn’t so sure, and he conducted experiments to establish whether bees are able to build perfect honeycombs using nothing but evolved and inherited instincts, as his theory of evolution would imply.
Why hexagons, though? It’s a simple matter of geometry. If you want to pack together cells that are identical in shape and size so that they fill all of a flat plane, only three regular shapes (with all sides and angles identical) will work: equilateral triangles, squares, and hexagons. Of these, hexagonal cells require the least total length of wall, compared with triangles or squares of the same area. So it makes sense that bees would choose hexagons, since making wax costs them energy, and they will want to use up as little as possible—just as builders might want to save on the cost of bricks. This was understood in the 18th century, and Darwin declared that the hexagonal honeycomb is “absolutely perfect in economizing labor and wax.”
Darwin thought that natural selection had endowed bees with instincts for making these wax chambers, which had the advantage of requiring less energy and time than those with other shapes. But even though bees do seem to possess specialized abilities to measure angles and wall thickness, not everyone agrees about how much they have to rely on them. That’s because making hexagonal arrays of cells is something that nature does anyway…
More at: “Why Nature Prefers Hexagons,” from @philipcball in @NautilusMag.
* Albert Einstein
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As we study structure, we might spare a thought for Agostino Bassi; he died on this date in 1856. An entomologist, he discovered that the muscardine disease of silkworms was caused by a very small parasitic organism, a fungus that would be named eventually Beauveria bassiana in his honor. The insight led him to argue that not only animal (insect), but also human diseases are caused by other living microorganisms (e.g., measles, syphilis, and the plague)– meaning that he preceded Louis Pasteur in the discovery that microorganisms can be the cause of disease (the germ theory of disease).
“Can’t have dirty garbage!”*…
Rebecca Alter, with a paean to an unexpected TikTok delight…
At some point earlier this year, my For You Page changed for the better. Between cute boys making sandwiches, Brian Jordan Alvarez videos, and American Girl Doll memes, I started getting the occasional video from @nycsanitation. I don’t think I’ve ever watched through a full video on TikTok from any government department, local or federal, but @nycsanitation has clawed its way through algorithms and attention spans to be that rarest of finds: an official organization or company account that’s actually good. The Department comes across in its TikToks as a bunch of genuine, hardworking salt-of-the-earth folks. I mean that literally; @nycsanitation TikTok reminds us that they’re the ones in charge of salting the streets in winter…
Read on for wondrous examples featuring googly-eyed snowplow trucks and earnest charm: “The Department of Sanitation Has an Oddly Excellent TikTok,” from @ralter in @Curbed.
* Spongebob
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As we keep it clean, we might might recall that it was on this date in 1865 that Joseph Lister, a student of Pasteur’s germ theory, performed the first successful antiseptic surgery (using carbolic acid to disinfect a compound fracture suffered by an 11-year-old boy). After four days, he discovered that no infection had developed, and after a total of six weeks he was amazed to discover that the boy’s bones had fused back together, without suppuration. He subsequently published his results in The Lancet in a series of six articles, running from March through July 1867.
Lister developed his approach to extend to Lister instructing surgeons under his responsibility to wear clean gloves and wash their hands before and after operations with five per cent carbolic acid solutions. Instruments were also washed in the same solution, and assistants sprayed the solution in the operating room.
At first, his suggestions were criticized: germ theory was in its infancy and his techniques were deemed too taxing. But his results– sharp reduction in post-op infection and death– ultimately carried the day. Indeed, he so revolutionized his field that he is known as “father of modern surgery.”
“I lit a thin green candle to make you jealous of me, but the room just filled up with mosquitoes”*…
It turns out that, if you’re looking for them, the words “mosquitoes,” “fever,” “ague,” and “death” are repeated to the point of nausea throughout human history. (And before: … when the asteroid hit, dinosaurs were already in decline from mosquito-borne diseases.) Malaria laid waste to prehistoric Africa to such a degree that people evolved sickle-shaped red blood cells to survive it. The disease killed the ancient Greeks and Romans—as well as the peoples who tried to conquer them—by the hundreds of thousands, playing a major role in the outcomes of their wars. Hippocrates associated malaria’s late-summer surge with the Dog Star, calling the sickly time the “dog days of summer.” In 94 B.C., the Chinese historian Sima Qian wrote, “In the area south of the Yangtze the land is low and the climate humid; adult males die young.” In the third century, malaria epidemics helped drive people to a small, much persecuted faith that emphasized healing and care of the sick, propelling Christianity into a world-altering religion…
In total… mosquitoes have killed more people than any other single cause—fifty-two billion of us, nearly half of all humans who have ever lived. [They are] “our apex predator,” “the destroyer of worlds,” and “the ultimate agent of historical change.”…
They slaughtered our ancestors and derailed our history– and they’re not finished with us yet: “How Mosquitoes Changed Everything.”
* Leonard Cohen
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As we nestle under our nets, we might spare a thought for Girolamo Fracastoro; he died on this date in 1553. A physician, poet, and scholar of mathematics, geography, and astronomy, he he proposed (in 1546) that epidemic diseases are caused by transferable tiny particles or “spores” that could transmit infection by direct or indirect contact or even without contact over long distances; he called these infectious agents fomes, from the Latin, meaning tinder. His theory was influential for three centuries, until it was sufficiently refined and extended to become modern germ theory, which superseded Fracastoro’s model.
Girolamo Fracastoro, by Titian c. 1528
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