Discovery of bacteria in humans: Sept. 17, 1683
Antonie van Leeuwenhoek, a Dutch merchant who has taught himself how to build a microscope, sends a letter to the Royal Society of London detailing the strange things he has found living inside his mouth. Van Leeuwenhoek explains how, after scraping plaque from his teeth and putting it under his microscope, he was able to see, “with great wonder,” many microscopic organisms that he called “animalcules.”
He writes that they were “very prettily a-moving” and that “the biggest sort had a very strong and swift motion, and shot through the water (spittle) like a pike does through water.” The second sort, he says, “oft-times spun round like a top. . . and these were far more in number."
Leeuwenhoek also describes what he had discovered in the plaque of two old men who had never brushed their teeth in their lives. He observed “an unbelievably great company of living animalcules, a-swimming more nimbly than any I had ever seen up to this time. The biggest sort. . . bent their body into curves in going forwards. . . Moreover, the other animalcules were in such enormous numbers, that all the water. . . seemed to be alive.”
Leeuwenhoek’s letter is the first record of bacteria seen living inside the human body.
It’s not the first time that Leeuwenhoek has shared his discoveries with the Royal Society. Ten years earlier, he had first sent the organization a letter detailing his observations of what mold, lice and even bee stings looked like under a microscope. But in 1676, Leeuwenhoek had described something that the members of the Royal Society didn’t believe was possible—he insisted that he had discovered microscopic living things inside pond scum scraped from a lake near his home. They remained dubious until Leeuwenhoek convinced them to see for themselves. And they found that he had been right—there were countless one-cell organisms moving around in the water.
The scientists no longer doubted Leeuwenhoek’s findings–not in 1677 when he became the first person to observe spermatozoa swimming in human sperm, nor in 1682, when he described the nucleus inside the red blood cells of fish, and certainly not the following year when he shared his story about the strange tiny creatures he found inside his mouth.
Roughly 100 years later, in 1877, the Royal Society established the Leeuwenhoek Medal, awarded each decade to the person judged to have made the most significant contributions to the field of microbiology. One of the first winners was Louis Pasteur, who not only demonstrated that fermentation was caused by the growth of bacteria, but also discovered that a process that became known as “pasteurization” could kill bacteria.
It wasn’t until 1876—200 years after Leeuwenhoek first saw bacteria “very prettily a-moving” under his microscope—that a German doctor named Robert Koch proved that those little organisms can cause disease.
More slices of history
"Electronic skin" could dramatically improve breast cancer detection
Scientists at the University of Nebraska-Lincoln are working on developing “electronic skin,” which they say could be used to detect hard-to-find lumps of potentially cancerous breast tissue.
The electronic device is made from nanoparticles and polymers and work by creating images of features within breast tissue. The researchers tested the device by placing lump-like objects within a piece of silicone, to which they then applied the electronic skin device.
The researchers found that the electronic skin was able to identify lumps as small as five mm and as deep within the silicone as 20 mm. Such measurements would be difficult to detect in conventional breast cancer screening methods, including mammography and clinical breast exams (CBE), the researchers said.
The study’s findings, published in ACS Applied Materials & Interfaces, suggest that the electronic device may not only be used to help detect breast cancer, but may also be helpful in looking for early signs of melanoma and other cancers.
Standing at work can reduce back pain
Standing for 30 minutes at a time may help alleviate back pain for people who typically for long periods of time at work, according to a new study.
Scientists at the Baker IDI Heart and Diabetes Institute in Melbourne, Australia recruited 17 middle-aged men and six women, who were randomly assigned to two groups. One group was asked to sit while working for eight hours, while the other group was asked to alternate between sitting and standing every 30 minutes for the same amount of time. The workers did this for five days, after which they switched roles for five more days.
At the end of each work week, the participants were asked to fill out a questionnaire about their fatigue levels, aches and pains and productivity.
The researchers found that the workers who alternated sitting and standing experienced about 15 percent less fatigue than did those who only sat while working. The sit-stand group also experienced 32 percent less lower back pain and 14 percent less pain in their ankles and feet. Both groups reported having about the same productivity levels.
The study’s findings, published in Occupational and Environmental Medicine, adds evidence that supports the benefits of reducing sedentary behavior, researchers said. Experts suggest office workers get more standing time by walking over to talk to colleagues instead of emailing, taking stairs instead of elevators or considering getting a standing desk.
Alcohol and pot have different consequences
Results from a recently-conducted survey show that U.S. teens perceive alcohol and marijuana as having different consequences.
The survey was conducted on high school seniors between 2007 and 2011 and included questions about history of alcohol and marijuana use and whether either substance resulted in any of 15 consequences, including compromised relationships, emotional instability and unsafe driving.
The results showed that the teens who had used alcohol—about 97 percent of those involved in the study—reported more regrettable behavior, more unsafe driving, compromised relationships with peers and less emotional stability. The teens who had used marijuana—about 60 percent of those involved in the study—reported compromised relationships with authority figures, worse school performance and having less energy.
The survey also found that about 25 percent of teens who had used alcohol said that it led to behaviors which they later regretted, compared to six percent of teens who had used marijuana.
The study suggests that teenagers may perceive marijuana as less dangerous, but researchers concluded that both substances are unhealthy and that parents should try to educate kids and keep them away from both.
Higher suicide rate linked to sunny days
It may seem counterintuitive but sunlight exposure may play a role in suicide rates, according to new a new study.
Previous research has found links between higher suicide rates and certain seasons—typically spring and winter—but the new study suggests that light may affect those rates in any given season.
In the study, scientists in Austria examined data on the amount of daily sunshine and nearly 70,000 suicides in Austria—in which there are four distinct seasons—between the years 1970 and 2010.
The researchers found a link between higher suicide rates and more hours of daily sunshine on the day of the suicide as well as more sunshine on up to 10 days prior, which seemed to facilitate suicide. The link between sunshine and suicide rate seemed to remain consistent for both “violent” suicide methods—such as hanging and shooting—and nonviolent methods, such as poisoning and was found to be stronger among men.
The results of the study, published in the journal JAMA Psychiatry, explain that the link between suicide rates and sunshine may exist because light interacts with chemicals in the brain, which can affect mood, impulsiveness and aggression.
The study’s findings are not significant enough to conclude that sunlight triggers higher suicide rates, but researchers said that future studies may point to whether the link holds true.