Glowing Mouse Heads and How Our Brains Get Washed

Herewith, edited excerpts from a Washington Post article of special interest to people with brains:

The lymph network carries immune cells throughout the body and removes waste and toxins. It was accepted wisdom for more than 300 years that the network didn’t extend into the brain. 

Three years ago, scientists trying to develop a more precise map of the lymphatic system used genetically-modified mice whose lymphatic vessels glowed when illuminated by a particular wavelength of light. The mice had been given a gene from a species of glowing jellyfish.

Seeing that the mouse’s heads glowed, the researchers realized that the lymphatic vessels extended into the brain after all. This was surprising, to say the least: In the 21st century, major findings involving basic human anatomy are rare. “These days, you don’t make discoveries like this”, one of the scientists said.

Since the lymph network also extends into human brains, this discovery has major implications for a wide variety of brain diseases, including Alzheimer’s, multiple sclerosis, stroke and traumatic brain injury.

Researchers have identified two networks: the vessels that lead into and surround the brain, and those within the brain itself. The latter is called the “glymphatic” system for the glia, the kind of neuron that makes up the lymphatic vessels in the brain. The glymphatic vessels carry cerebrospinal fluid and immune cells into the brain and remove cellular trash from it.

There is evidence that when the systems malfunction, the brain can become clogged with toxins and suffused with inflammatory immune cells. Over decades, this process may play a key role in Alzheimer’s disease, Huntington’s disease, Parkinson’s disease and other degenerative illnesses. 

“This is a revolutionary finding,” one researcher says. “This system plays a huge role in the health of the brain.” She describes the glymphatic system as like a dishwasher for the brain. “The brain is very active and so it produces a lot of junk that needs to be cleaned out.”

In hindsight, the system should have been noticed long ago. When the skull and head are dissected, the vessels are visible to the naked eye. But no one bothered to really look.

The vessels have also been implicated in autoimmune disease, such as multiple sclerosis. Researchers knew that the immune system has limited access to the brain. But at the same time, the immune system kept tabs on the brain’s status; no one knew exactly how. Some researchers theorize that the glymphatic system could be the conduit. In diseases like multiple sclerosis — where the body’s immune system attacks certain brain cells — the communication may go awry.

Recently, Harvard University researchers reported that glymphatic flow is significantly decreased in the period just before a migraine. The intense pain in these headaches is caused largely by inflamed nerves in the tissue that surrounds the brain. The authors of the study theorize that faulty clearance of molecular waste from the brain could trigger inflammation in these pain fibers.

One key to glymphatic performance seems to be sleep. At least in mice, the system processes twice as much fluid during sleep as it does during wakefulness. It’s possible that sleep dysfunction may contribute to Alzheimer’s and perhaps other brain illnesses: “You only clean your brain when you’re sleeping. This is probably an important reason that we sleep. You need time off from consciousness to do the housekeeping”.

It also appears that sleep position is crucial. In an upright position — someone who is sitting or standing — waste is removed much less efficiently. Sleeping on your stomach is also not very effective; sleeping on your back is somewhat better, while lying on your side appears to produce the best results. The reason for these differences might be related to the mechanical engineering of the lymphatic vessels and valves; the healthiest approach may be to move periodically while you sleep.

Sleep is probably not the only way to improve glymphatic flow. Omega-3 fatty acids and deep breathing may also improve glymphatic functioning. 

Not being a scientist, I can’t evaluate these studies, but it makes sense that brains produce a lot of junk that needs to be cleaned out. (And you didn’t think the President would come up in this post.)

Your Doctors Might Kill You But Going to the Dentist Will Be a Breeze

Two pieces of medical news caught my eye this past week.

First, according to the New York Times, physicians at the highly-respected University of Pittsburgh Medical Center are going to start putting selected patients to death. Not through improper care, but on purpose.

The idea is that patients who come into the emergency room on the brink of death because of a life-threatening injury will occasionally have all of their blood replaced with freezing salt water. That means their hearts will stop beating and their brains will stop working. They’ll be dead.

This will be done in order to give surgeons more time to do their job. Instead of having a few minutes to address the gunshot wound or other injury, they may have up to an hour to operate before the patient suffers brain damage. The medical staff will then resuscitate the patient by replacing the cold salt water with nice warm blood.

This procedure has been successfully used on animals like pigs and dogs, but never before on a person. The hospital is planning to perform Emergency Preservation and Resuscitation (EPR) about once a month for a couple of years before reaching a decision on its effectiveness.

One might think that killing your patient is a clear violation of the medical maxim: “first, do no harm” (primum non nocere). But since the patients in question will already be in cardiac arrest, and very likely to die anyway, and since the kind of death they’ll suffer is expected to be temporary and should give them a much better chance of surviving their injury, it isn’t clear that the doctors will be harming anyone, at least in the usual sense.

Perhaps a more troubling issue is that patients being subjected to this kind of procedure won’t be in a position to give their consent. They’ll already be unconscious. So the medical center has publicized this new procedure in and around Pittsburgh and given prospective patients the opportunity to opt out if they choose. But the default setting in case you’re ever shot or stabbed in western Pennsylvania and end up in the UPMC emergency room will be to receive EPR (and possibly meet your maker), if you are a suitable candidate.

The other news that caught my eye is that researchers in England claim to have come up with a new treatment for tooth decay. The procedure is called Electrically Accelerated and Enhanced Remineralisation (EAER). Dentists will use a very small electrical current to accelerate “the natural movement of calcium and phosphate minerals into the damaged tooth”. In effect, your tooth will heal itself with some encouragement from your dentist. The procedure wouldn’t require an anesthetic, drilling or a filling (and dentists would become more popular people).

It isn’t clear from the article in the Guardian how long it will take to fix a cavity this way. In an ideal world, your cavities could be repaired through EAER at the same time your gunshot wound was repaired through EPR. But that probably won’t be possible for a few years yet.

Bacteria Are Our Friends, Except When They’re Not

It’s good to remind ourselves occasionally that we human beings are little worlds of a sort. Each of our bodies is composed of trillions of cells (about 40 trillion, based on a recent estimate), each going about their individual business, and many more microorganisms, mainly bacteria, each going about their business too.

I’m not sure why it’s good to remind ourselves of this fact, but it seems like something worth keeping in mind. It might, for example, help us not be so fearful of bacteria. They’re not necessarily bad for us. For one thing, they help us with digestion. More surprisingly, some scientists believe that, before people began frequent applications of soap and shampoo, one kind of bacteria (Nitrosomonas eutropha) flourished on people’s skin, acting as a “built-in cleanser, deodorant, anti-inflammatory and immune booster by feeding on the ammonia in our sweat and converting it into nitrite and nitric oxide”.

That’s the theory behind an article in the New York Times by a woman who went one month without using soap or shampoo. Aside from her greasy hair, she didn’t notice any ill effects. Nobody complained about her odor. In fact, after encouraging the growth of N. eutropha on her body for a month, her skin was in better shape than when she started the experiment. The scientists involved hope that bacteria might one day be used to treat various skin conditions, like eczema and acne, and even help certain wounds heal more quickly.

That’s the good news. The bad news (which is much worse than the other news is good), is that medical authorities are calling attention yet again to the spread of dangerous antibiotic-resistant bacteria. The Guardian reports that a group of senior British scientists expressed concern last week that we face “the prospect of people dying from routine infections because effective antibiotics no longer exist”. One scientist said:

In the near future it is possible that a scratch from a rose thorn could become septic. Without effective antibiotics, septicaemia could easily set in and result in death. It is a terrible prospect, but a very real one. We are facing a return to the state of affairs that existed before antibiotics were discovered.

Any kind of surgery and treatments that affect the immune system could all become life-threatening. As a stop-gap measure, the scientists recommend that hospitals go back to having old-fashioned rooms with widely-separated beds and windows that can be opened to allow in fresh air. 


Unfortunately for us communities of cells and bacteria, the drug companies aren’t developing new antibiotics, because there is little profit to be made off drugs that people only take for a short period of time. Chalk another one up for capitalism and the free market. 

As dangerous bacteria continue to evolve, it becomes increasingly likely that epidemics will sweep the world before new antibiotics or other treatments will be available, unless there is increased government support for the needed research. The alternative is to wait for the problem to get so bad that it becomes profitable to fix it. 

Taking these developments into account, it’s safe to assume that one day many of us will be dead from bacterial diseases we don’t know how to fight. But our skin will be in the best shape ever.

Medical News To Be Thankful For

Some filibuster-reform in the Senate and the Pope expressing himself on the subject of global capitalism aren’t the only events in the news to be thankful for. For example, an editorial and an accompanying story in The New Scientist call attention to a promising development in the treatment of cancer:

Cancer is a many-headed hydra: it rapidly out-evolves treatments that target specific features of cancer cells. Even superficially identical tumours contain many different mutations, making therapy for one type useless against others.

Armed with this information, researchers are focusing on approaches that stimulate patients’ own immune systems to attack their tumour. Unlike drugs, immune systems can evolve as the cancer does, staying one step ahead of new mutations. This is how treatments based on a type of white blood cell called T-cells are curing some cancers, rather than just slowing their advance.

This new therapy involves immune cells taken from the patient and then genetically-engineered to attack the patient’s cancer cells. The modified T-cells leave healthy cells alone. Earlier this year, one patient’s “incurable” leukemia disappeared in eight days.

I have no idea whether this treatment will eventually lead to a cure for cancer (and one that is available to lots of patients), but using genetic engineering to help the body’s own immune system attack cancer sounds like an important step in the right direction.

From the New Scientist article: