Digitally enhanced image of human heart. Wellcome Images.
Caf-fiends in a can
If your heart beats faster at the thought of quaffing a cold can of energy drink (think Red Bull, Monster, Rockstar and their ilk), there may be something wrong with you more worrisome than your sense of taste.
Almost nobody drinks these hugely popular concoctions for their sublime flavor. They are consumed almost entirely for the much touted neurological jolt derived from an overabundance of stimulating caffeine (as much as three times more than in a comparable serving of coffee or soda) and ingredients like B vitamins, the amino acid taurine, guarana, a South American plant with a higher caffeine concentration than coffee, ginseng and ginkgo biloba.
Judging from sales - $12.5 billion in 2012 in the U.S. alone – these commercial energy drinks deliver their promised punch – and worse.
A report presented this week at the Radiological Society of North America found that energy drinks appear to adversely alter heart function. Specifically, they can cause rapid heart rate, palpitations, a blood pressure spike and, possibly, seizures or death.
If that’s not enough of an eye-opener, consider this statistic from the Substance Abuse and Mental Health Services Administration: Each year almost 21,000 energy drink consumers find themselves in hospital emergency rooms being treated for unwanted side effects of the beverages.
So next time you need something to snap you awake, try water – eight icy cold ounces dashed to the face generally does the trick.
Human goblet cell. Image courtesy of the University of Edinburgh, Wellcome Images
Raise a glass to the goblet cell
In a paper published last week in Virology Journal, Pascal Gagneux and colleagues at UC San Diego School of Medicine describe how influenza A viruses snip through the protective mucus net to both infect respiratory cells – and then later cut their way out infect other cells.
Mucus is usually deemed a disgusting annoyance, but really it’s not. (Sorry, couldn’t resist.) It is oil in the human engine, lubricating the passages of the mouth, nose, sinuses, throat, lungs and gastrointestinal tract, preventing underlying epithelial tissues from drying out. It’s also a sort of sticky flypaper, trapping unwanted substances like bacteria and dust before they can too deeply penetrate the fairly pristine and sterile inner body.
Each day, a healthy person churns out about 4 to 6 cups of mucus. Most of it trickles down your throat unnoticed. The little factories that make mucus are called goblet cells. It’s an apt moniker because goblet cells are little more than vessels filled to the brim with globules of mucin. That’s a globule cell in the image above; the mucin globules colored blue.
Mucins are glycosylated proteins, but you can think of them more simply as dehydrated bits of mucus packed inside a globule cell. Once released into the water-rich environment of your airways, however, they expand rapidly, absorbing water to reach full, gooey size within 20 milliseconds. That’s one-thousandth of a second. That’s fast. A single flap of a hummingbird’s wing takes 5 to 80 milliseconds.
The rapid release allows goblet cells to respond almost instantly to many different stimuli, from inhaled microbes to a mouthful of eye-watering wasabi.
Tongue bacteria. Image courtesy of Steve Gschmeissner
That’s a mouthful
This week, Rob Stein at NPR concluded his series on the human microbiome with a look at research investigating how our multitudinous intestinal bacteria may influence brain development and function. Turns out that old notion about “gut feelings” might have a biological basis.
These days, microbiome research is on everybody’s tongue, and thus the inspiration for today’s image: a colorized scanning electron micrograph of bacteria residing on a human tongue.
It should be no surprise that the human mouth is home to hundreds of microbial species. After all, it’s warm, moist and frequently open for business. It doesn’t start that way. A newborn has no bacteria in its oral cavity, but that soon changes – and changes even more as the mouth develops. Gums, cheeks and emerging teeth all provide distinct environmental niches for different bacterial species.
Some of these species are beneficial, aiding in digestion, for example. Many others are offer no direct benefit, but are helpful in occupying space that might otherwise be taken up by nastier bugs, such as those that cause tooth decay, periodontal diseases and worse. Poor oral hygiene has been linked to poor health elsewhere, including a higher risk of heart attack and cardiovascular disease.
Like fingerprints, everyone’s tongue is different. It’s the same with the assemblages of bacteria that call our mouths home. A recent microbial survey identified almost 400 different species in the mouths of 100 participants representing four different ethnic affiliations. Only 2 percent of the bacterial species were present in all of the individuals, albeit in different concentrations according to ethnicity. Eight percent were detected in 90 percent of the group. But most interestingly, said the researchers, each ethnic group – non-Hispanic blacks, whites, Chinese and Latinos – was identifiable by its own “signature” of shared microbes.
Hans von Gersdorff was one of Germany’s most noted surgeons during the late 15th and early 16th centuries, though little is known about the personal life or background of the man. He is best remembered for his illustrated Feldbuch der Wundartzney or Fieldbook of Surgery.
Based largely upon the writings of famed medieval surgeon Guy de Chauliac, Gersdorff’s tome was widely used as a basic surgical text for many years, most notably for its advice on limb amputation, which Gersdorff was reputed to be much experienced, with at least 200 procedures.
Feldbuch contained numerous woodcut images of surgical procedures, such as trephining and bone setting, anatomical schematics and diseases or medical conditions, such as leprosy. The woodcuts were done by Johann Ulrich Wechtlin.
Many of the images created by Gersdorff and Wechtlin were quite technical, if not always complete or precisely accurate. The image above, known as “Wound Man,” is likely intended to be more evocative in nature – a quick guide to injuries that military surgeons might see on a battlefield.
Gersdorff died in 1529 at the age of 74, presumably the consequence of old age and not from one of the mortal afflictions above.
Yesterday’s announcement of a $100 million gift from businessman and philanthropist T. Denny Sanford to create the Sanford Stem Cell Clinical Center at UC San Diego marks a major step in the journey to deliver the therapeutic potential of stem cells to actual patients-in-need.
It’s a long road, of course, with plenty of hills and valleys ahead, but as the process goes forward, a look back at some of the UC San Diego stem cell research fueling that effort.
- Scanning electron micrograph (false color) of a human induced pluripotent stem cell-derived neuron. Thomas Deerinck/UC San Diego
- A human neuron derived from stem cells in the brain of a mouse. Alysson Muotri/UC San Diego
- Stem cell-derived human neurons (red and green) in the spinal cord of a rat. Martin Marsala/UC San Diego
- Two neurospheres (clusters of brain cells) derived from human induced pluripotent stem cells send neuronal processes (green) to connect to each other. The red indicate the nuclei of cells. Alysson Muotri/UCSD
- Neurons derived from induced pluripotent stem cells of patients with Alzheimer’s disease. Larry Goldstein/UC San Diego
Speaking of rats (OK, we weren’t but now that the subject’s been mentioned), we present the above laser scanning confocal micrograph of an en face section of epithelium of a rat’s tongue, produced by Tom Deerinck at the National Center for Microscopy and Imaging Research at UC San Diego.
The image slightly penetrates the superficial epithelium of the tongue and uses a variety of stains to highlight distinct structures. Most notable is the cross-hatched mesh of striated muscle fibers, whose actin (a contractile protein) glows fluorescently red. Cell DNA is stained blue. Cell membranes are highlighted in green.
Rats, of course, have long had a voice in medical research. They are among science’s most cherished model organisms, employed by researchers everywhere to study everything from autism to spinal cord injuries to the warming effects of eating durian while taking the painkiller paracetamol, otherwise known as acetaminophen, the active ingredient in Tylenol.
Some rat models are the product of targeted genetic engineering, but mostly they are useful for just being appallingly similar to human beings, biologically speaking. Or as in the case of the naked mole rat, utterly unlike us. The naked mole rat is a favorite in cancer research because, oddly enough, it is cancer-resistant. In decades of study, not a single incident of cancer has been detected in a naked mole rat, which makes it a fitting model for finding new ways to fight the disease.
Don’t yawn. Gotcha!
All vertebrates yawn spontaneously.
It’s not clear why, exactly, we all yawn. The scientific-sounding explanation that yawning allows us to suck in extra, rejuvenating amounts of oxygen is a myth. There’s no evidence that yawning affects levels of oxygen in the bloodstream, blood pressure or heart rate.
Contagious yawning is something else altogether, but equally mysterious. It happens when you see someone else yawning. It can happen if you just imagine someone else yawning.
Contagious yawning is believed to be an ancient act of social bonding employed by myriad species to signal their open-mouthed, involuntary empathy with others. Persons with autism, for example, are less likely to catch a yawn than others, though it’s not clear whether it’s a lack of empathy or merely inattention to facial cues.
Contagious yawning isn’t restricted to the same species. While it’s tough to induce a fish to yawn (apparently some do), it’s possible to make a dog yawn – or a chimpanzee.
A new study reports that chimps yawn after watching humans yawn, but it’s selective. Elainie Madsen, an evolutionary psychologist at Lund University in Sweden, explains in this video that young chimpanzees unfamiliar with a yawning human don’t necessarily gape in response, but older chimps that have spent time with the yawner are quite likely to yawn in harmony.
Contagious yawning comes naturally, but not immediately. It’s a learned behavior for both chimps and humans, not really catching on until the yawnee is three or four years old.
(Question: How many times did you yawn reading this story? On average, a normal, healthy adult yawns seven to nine times each day; each yawn lasting about six seconds.)
Chinese red-headed centipede
A drug idea with legs
Frankly, it’s a safe guess that any critter whose Latin name is Scolopendra subspinipes mutilans is going to be pretty scary (mutilans!). And, by all outward appearances, the Chinese red-headed centipede qualifies. It averages eight inches in length and packs a venomous bite.
In this case, though, you might want to reconsider outward appearances. According to ancient Chinese medical traditions, the centipede possesses distinctive healing properties. Apply one to a rash or wound and it’s supposed to heal faster.
Or not. The case for using centipedes as living Band-Aids is fairly anecdotal.
On the other hand, the bite of the bug might actually prove empirically healthful. Or more accurately, the venom contained in that bite.
In a new study, researchers in Australia and China say the centipede’s venom contains a pain-killing molecule potentially as effective as morphine. Specifically, the molecule targets a nerve channel called Nav1.7. “People without a functioning Nav1.7 channel cannot feel pain,” said Glenn King at the University of Queensland, “so it’s likely molecules that can block this channel will be powerful painkillers.”
(The centipedes presumably evolved the molecule to block similar nerve channels in insects, allowing them to kill and eat them more efficiently.)
More research and development is required, of course, to convert these basic findings into a usable drug, but the idea has been tried before. There are already a number of pain relievers on the market based upon animal venom, with more in the works, among them painkillers based upon the venoms of snakes, scorpions and, um, snails.
It should be noted that while cone snails are neither scary-sounding nor scary-looking, they are terrors of the sea. They are carnivorous and predatory and use a venomous harpoon to capture faster-moving fish. The venom of larger species is powerful enough to kill a human.
Conversely, Chinese red-headed centipedes tend to be non-aggressive and reportedly make fine pets, though you probably shouldn’t let them bite you.
Set to signal
The image above depicts a false-colored cross-section view of a synapse – the junction where signals pass from a neuron to another cell. The green-colored synaptic bouton (button) is a knoblike swelling at the end of a neuronal axon. It’s the megaphone, so to speak, through which a neuron talks to the rest of the world.
In this image, the bouton is surrounded by an insulating glial cell (speckled purple) that bumps up against a muscle fiber, the recipient of neuronal signals.
The thin, dark purple gap between the bouton and fiber is the synaptic cleft. Signal molecules are released by the bouton into this space and taken up by receptors on the receiving cell. Inside the bouton itself are mitochondria (dark blue circles), the power plants of cells, and vesicles (smaller, green circles) filled with yellow neurotransmitters.
The green vesicles take on particular celebratory note this week. The Nobel Prize for medicine or physiology was awarded yesterday to a trio of researchers – James E. Rothman, Randy W. Schekman and Thomas C. Sudhof – for their ground-breaking discoveries about the nature and functions of vesicles.
In citing their work, the Nobel Prize committee explained that the newly minted laureates had solved the mystery of how cells organize their transport system.
“Each cell is a factory that produces and exports molecules,” wrote the committee in their announcement. “For instance, insulin is manufactured and released into the blood and chemical signals called neurotransmitters are sent from one nerve cell to another. These molecules are transported around the cell in small packages called vesicles. The three Nobel Laureates have discovered the molecular principles that govern how this cargo is delivered to the right place at the right time in the cell.”
You can read the full Nobel Prize release here.
A labor of larva
“If I could train maggots to resect brain tumors, I would.”
It’s not often you read such a quote, this one coming from J. Marc Simard, MD, a neurosurgeon at the University of Maryland School of Medicine. Simard is commenting in an NPR story about employing a robotic version of flesh-eating larvae to crawl deep inside the brains of cancer patients to zap hard-to-reach tumors. He and colleagues already have a developed a half-inch-wide prototype. It vaguely resembles a multi-jointed, plastic pinkie finger.
It remains to be seen, of course, whether Simard’s robotic maggot – or something similar – will ever successfully worm its way into reality. In the meantime, let’s pause to celebrate the real, squishy thing, which has been approved for medical use since 2004.
The image above is that of the working end of a blue bottle fly maggot. Although its Latin name – Calliphora vomitoria – aptly captures our natural disgust with its preferred diet of decomposing matter (decaying meat, garbage, feces), the maggots’ utterly non-discriminating sense of taste and voracious appetite makes them ideal for cleaning out dead and dying tissue in flesh wounds.
Another study out of Germany reported that maggot secretions complement aspects of the host’s immune system response, spurring the healing process while modulating damaging inflammation.
Maggot therapy isn’t new. Humans have been using larvae for thousands of years to promote healing. Nature has been doing so much longer – and for more reasons.
But it’s good to occasionally offer a squeamish nod of thanks to the rice-sized critters, now officially considered to be a prescription-only medical device by the FDA. Until there is a robotic equivalent, they’re all we’ve got.