Tag Archives: acid

Elephant skin.

Collagen networks and hyaluronic acid literally keep you in shape, new study reports

Our tissues have to handle stress and deformation every day. New research is looking into how it copes so well.

Elephant skin.

Image via Pixabay.

We tend to take our bodies for granted but even the most mundane of actions — walking around, breathing — exerts mechanical stress and subsequent deformation of it. And yet, day after day, our tissues take the brunt of it with grace and even heal themselves without any conscious effort on our part.

Curious to see how it pulls off such a feat, researchers from the Wageningen University & Research (WUR) and the AMOLF Institute found that two components in soft tissue, collagen and hyaluronic acid, work together to underpin how tissues respond to mechanical stress.

Feeling stressed

Pull on your earlobe and it will be soft and flexible. Keep pulling, increase the force you apply, and it will become progressively stiffer. It’s not just your earlobes — skin, muscles, the cartilage in your joints and ribs behave the same way.

They’re designed to work like that. While soft, such tissues are easily traversed by cells — but they also need to provide mechanical protection to underlying structures, meaning it has to be tough too, and hard to break. Finally, it’s vital that such tissue is able to transition between the two states.

Needless to say, that’s quite a list of demands. But, our soft tissues rise to the challenge through the use of collagen, hyaluronic acid, and the interactions between the two, a new study reports. The findings not only help us better understand how our bodies function, but may also point the way towards new, synthetic polymers that mimic these impressive properties.

It’s the particular way in which collagen proteins order themselves in soft tissues that give them their resilience. They arrange in a structure known as a sparse network (meaning the proteins don’t form the maximum possible number of bonds between each other). Previous research has gauged the physical resilience of this sparse network in in-vitro conditions: collagen networks were extracted from samples of animal skin and reformed inside a rheometer, an instrument which measures the response of a material during deformation. Such efforts, the team explains, only capture part of the image, however.

“Real tissues are far more complex: they are composed of different molecules that have different sizes and interact with each other in still unknown ways,” says Simone Dussi, postdoc in the WUR Physical Chemistry and one of the study’s corresponding authors. “Because of this complexity, real tissues are way more adaptive than the networks studied so far, made of only collagen.”

“[The presence of hyaluronic acid] significantly changed the mechanical response of the composite networks and we were eager to understand why.”

The team reports that, unlike collagen, hyaluronic acid — a polymer made of much smaller and more flexible molecules — is electromagnetically charged. Because of this, electrostatic interactions generate stress between its individual blocks which accumulates as the tissue is subjected to deformation. According to the team, this buildup of stress basically opposes the deformation.

Networks with a larger amount of hyaluronic acid are “already stiffer at small deformation[s]”, explains co-author Justin Tauber. They also become stiffer in response to larger deformation than networks poor in the acid, the adds.

“We managed to construct a theoretical model and performed computer simulations that matched the experimental results. The key ingredients were identified: In addition to the network structure and the bending rigidity of the collagen fibres, the elasticity and the internal stress generated by the hyaluronic acid are crucial,” Tauber explains.

“The model allows us to make a step further in understanding how real tissues exploit the balance of all these effects. In addition, our findings can be translated into material science to create novel synthetic polymeric materials with more tunable properties.”

The paper “Stress management in composite biopolymer networks” has been published in the journal Nature.

Although they appear identical, baking powder and baking soda are slightly different. Credit: Eat By Date.

What’s the difference between baking soda and baking powder: science to the rescue

Although they appear identical, baking powder and baking soda are slightly different. Credit: Eat By Date.

Although they appear identical, baking powder and baking soda are slightly different. Credit: Eat By Date.

Baking soda and baking powder look and sound the same. To make matters even more confusing, they’re often used in the same recipes. However, knowing what sets these two popular ingredients apart could mean the difference between the perfect baked goods or a smooshed fiasco.

What’s baking soda

Baking soda is, essentially, ground up rock — which means it can last indefinitely (if properly stored). More specifically, baking soda is the colloquial term for sodium bicarbonate, a base that reacts quite energetically when encountering an acid such as buttermilk, yogurt, or vinegar (our brains register acid substances as ‘sour’). Mixing baking soda with an acid will produce carbon dioxide — because in this kitchen this reaction usually takes place in a liquid, it also produces bubbles. This property is what makes the substance so useful for bakers. Mix some baking soda into the proper dough, and it will generate carbon dioxide. As the mixture stiffens and the gas escapes, enlarged air pockets are left behind, making the end product fluffy and soft.

Due to this behavior, you’ll often see baking soda mentioned in recipes which include many acidic ingredients like molasses, maple syrup, lemon juice, and pumpkin. In such cases, baking soda works as a leavener, helping the dough rise.

When added to a mixture, baking soda will raise the pH, slowing down protein coagulation — the process that leads to the stiffening of a food as it cooks or bakes. This helps the bake good spread before it sets, helping the food bake more evenly.

Baking soda is also an excellent cleaning agent.  It’s a super-effective (but gentle) abrasive and is a great natural deodorizer, so it’s helpful in all sorts of cleaning emergencies, from unclogging drains to deodorizing the carpet.

Someone who sure loves baking soda…

What’s baking powder

Sometimes, you don’t want the rising to take place all at once, which is where baking powder comes in. Baking powder is a mix made from baking soda (sodium bicarbonate) and two acids for it to interact with and produce CO2 gas at different stages of the baking process. This is “double acting” baking powder; single-acting baking powder contains only one acid, which reacts fully when you combine it with another liquid.

One of the acids in baking powder is monocalcium phosphate, which unlike most acids — like, say, vinegar — doesn’t immediately react with the sodium bicarbonate while it’s dry. It’s only when the sodium bicarbonate is wet, such as when it’s stirred into a wet dough, that the two ingredients begin to react, releasing CO2 bubbles and causing chemical leavening.

Baking powder usually contains a second acid, typically sodium acid pyrophosphate or sodium aluminum sulfate (soda alum), which extends the chemical leavening process. Neither of the two acids will react with the base until the sodium bicarbonate is both wet and hot — in other words, not until you put the dough in the oven. This way, the batter can rise for a longer period of time, leading to a fluffier cake or muffin. Without the two special kinds of acids, baking powder’s heavy lifting powers in the oven would be gone — and we’d all end up with some pathetic, saggy bake goods.

Since baking powder is only one-fourth baking soda, it is also just one-fourth as powerful as baking soda. The upside, when using baking powder, it that it isn’t necessary to add an acid. Instead, baking powder starts to work when any liquid is added.

Both baking powder and baking soda need to be stored in a cool and dry place. The extra moisture in the air can start the reaction between the acids and base. And like baking soda, it is important to bake the mixture right away, or else the mixture will collapse.

So, there you have it: baking soda is made out of a single ingredient, while baking powder is a mix of baking soda and at least one acid. But which of the two should you use in the kitchen? That’s simple: when baking a recipe which already contains an acid as one of the ingredients, use baking soda. If there are no acids in your recipe, use baking powder instead.

Happy baking!

LSD gets stuck in your brain — literally. This could help us develop better (health) drugs

A new study sheds some light on what drug-takers have known or years: acid trips last a long time.

LSD literally gets stuck in your brain. Image credits: ssoosay.

Hallucinogenic drugs usually last a few hours. The effects vary depending on several factors, but on all accounts, LSD (most commonly known as acid, among many other names) lasts for a very long time — up to 12 hours. This is truly unique, no other hallucinogenic drug comes even close to that. Researchers have known and studied this in the 60s and 70s but couldn’t find the reason why it happens and since then, laws and regulations have become stricter and it’s much more difficult to conduct such studies. But interest in hallucinogenic drugs hasn’t declined, and a new study found the mechanism behind acid’s surprising resilience. After it’s ingested, the drug travels into brain receptors where it gets literally stuck in a side pocket.

Researchers first suspected something strange was up when they tested LSD’s half life. They learned that LSD stays in the blood for about an hour. Why, then, are the drug’s effects so long lasting? Even after it couldn’t be detected in a person’s bloodstream, the drug’s was still strong and kicking. To figure out this mystery, scientists used crystallography imaging to see how the molecules are arranged in LSD. They zoomed in on this molecular geometry, and then fitted it inside a serotoning receptor. These receptors are located thorughout the body and brain, and when LSD attaches to them, you get the hallucinogenic effects the drug is famous for. The team then showed that when LSD attaches itself to a side pocket of these serotonin receptors, it does so at an angle that basically doesn’t allow it to get out afterwards. The receptor’s protein folds over the LSD molecule, trapping it even more.

Bryan Roth, one of the study’s authors and a pharmacology professor at the University of North Carolina at Chapel Hill, said that the effect is unique to LSD, and opens up interesting gateways to drug administration. The really cool thing about this study is that it not only helps us understand how acid trips you for so long, it could actually have major implications for conditions such as schizophrenia and depression. Basically, we could learn from LSD and engineer drug molecules to be more like it, so that they too get trapped by the serotonin receptors and have stronger effects. Furthermore, it could be that the same thing happens for other receptors as well (though this hasn’t been researched yet), potentiall opening even more doors for drug administration.

This also seems to confirm what many drug-takers have been saying for a long time– that even very low doses (which shouldn’t, in theory, do anything) of LSD provide a tangible effect. This so-called microdosing is particularly interesting for doctors and has been researched extensively, because it implies that you need fewer molecules to get the job done, thus limiting side effects and reducing the quantity of required drug. This is still a work in progress, but Roth is confident.

He also says that they will start work on developing drugs based on this newly acquired knowledge, firstly focusing on schizophrenia. Hopefully, he added, they will have tangible results within a year or two.

Journal Reference: Daniel Wack et al — Crystal Structure of an LSD-Bound Human Serotonin Receptor. DOI: http://dx.doi.org/10.1016/j.cell.2016.12.033

The Permian extinction – caused by “lemon juice” acidic rain ?

  • The Permian extinction was the biggest extinction ever, killing 96% of all marine species and 70% of terrestrial vertebrates
  • Possible causes include: impact, loss of oxygen and volcanic eruptions
  • Researchers tested the validity of the last hypothesis, finding it likely

The biggest extinction – ever

Artistic representation of the Permian plants, affected by acidic rain. Via MIT.

Artistic representation of the Permian plants, affected by acidic rain. Via MIT.

MIT Researchers believe that rain as acidic as undiluted lemon juice may have contributed to massive extinction that took place at the end of the Permian, 252 million years ago. These acidic rains may have played a part in killing off plants and organisms around the world during what is regarded as the most severe extinction the world has ever gone through.

It was so severe that it killed 96% of all marine species and 70% of terrestrial vertebrate species – and it took life about 10 million years to recover from it!

Pin-pointing the exact cause (or causes) of the Permian–Triassic extinction event is a difficult undertaking because it took place so long ago that most of the evidence was destroyed, eroded or buried away. There’s a major scientific debate, centering on several potential causes:

– an asteroid impact, similar to what wiped off the dinosaurs at the end of the Mesozoic
– a gradual, global loss of oxygen in the oceans
– a host of environmental changes caused by massive volcanic eruptions in today’s Siberia.

Now, researchers at MIT have simulated the final possibility. They created a climate model for a Permian world in which massive eruptions took place, ejecting volcanic gases (including sulfur) into the atmosphere. They found that if this were the case, then sulfur emissions were significant enough to create widespread acid rain throughout the Northern Hemisphere, with pH levels reaching 2 — as acidic as undiluted lemon juice. These acidic rains alone would have been enough to maim virtually all living plants, halting their growth and development, ultimately leading to the massive extinction.

“Imagine you’re a plant that’s growing happily in the latest Permian,” says Benjamin Black, a postdoc in MIT’s Department of Earth, Atmospheric and Planetary Sciences. “It’s been getting hotter and hotter, but perhaps your species has had time to adjust to that. But then quite suddenly, over the course of a few months, the rain begins to sizzle with sulfuric acid. It would be quite a shock if you were that plant.”

Volcanoes in Siberia

The world at the time of the Permian extinction. Highlighted are the biggest igneous provinces - notice Siberia.

The world at the time of the Permian extinction. Highlighted are the biggest igneous provinces – notice Siberia. Source

It’s hard to wrap your mind around such a dramatic event as this one, and in a way, it’s hard to believe that it was just a single cause – it seems pretty likely that at least a couple of separate, unfortunate elements converged towards this extinction. Geologists analyzing the rocks in Siberia found evidence of immense volcanism that came in short bursts beginning near the end of the Permian period and continuing for another million years. The volume of the magma was several million cubic kilometers, enough to put a thick cover over all the United States. But even so, were these eruptions enough on their own?

The group simulated 27 scenarios, each approximating the release of gases from a plausible volcanic episode, including a wide range of gases in their simulations, based on estimates from chemical analyses and thermal modeling. They then modeled the interaction between these gases and the atmosphere, ultimately, how they were absorbed and then came down as low pH rain.

They found that with repeated bursts of volcanic activity, the acidic rains had a dramatic effect on land plants, probably going way past the point they could handle.

“Plants and animals wouldn’t have much time to adapt to these changes in the pH of rain,” Black says. “I think it certainly contributed to the environmental stress which was making it difficult for plants and animals to survive. At a certain point you have to ask, ‘How much can a plant take?’”

Now, Black hopes paleontologists and geochemists will consider his own results and compare them with their own observations of the Permian extinction, in order to paint a more accurate picture.

“It’s not just one thing that was unpleasant,” Black says. “It’s this whole host of really nasty atmospheric and environmental effects. These results really made me feel sorry for end-Permian organisms.”

Lifeless prions are capable of evolution

prionsup35Researchers from the Scripps Research Institute have determined for the first time that prions, which are just bits of infectious protein without any DNA or RNA that can cause fatal degenerative diseases are capable of Darwinian evolution.

This study shows that prions do develop significant large numbers of mutations at a protein level as a response to external influences, and through natural selection, they can eventually lead to mutations such as drug resistance.

“On the face of it, you have exactly the same process of mutation and adaptive change in prions as you see in viruses,” said Charles Weissmann, M.D., Ph.D., the head of Scripps Florida’s Department of Infectology, who led the study. “This means that this pattern of Darwinian evolution appears to be universally active. In viruses, mutation is linked to changes in nucleic acid sequence that leads to resistance. Now, this adaptability has moved one level down — to prions and protein folding — and it’s clear that you do not need nucleic acid for the process of evolution.”

This also started another discussion, well actually restarted it, that of the quasi-species. First launched 30 years ago, this idea basically suggest a complex, self-perpetuating population of diverse and related entities that act as a whole.

“The proof of the quasi-species concept is a discovery we made over 30 years ago,” he said. “We found that an RNA virus population, which was thought to have only one sequence, was constantly creating mutations and eliminating the unfavorable ones. In these quasi-populations, much like we have now found in prions, you begin with a single particle, but it becomes very heterogeneous as it grows into a larger population.”

“It’s amusing that something we did 30 years has come back to us,” he said. “But we know that mutation and natural selection occur in living organisms and now we know that they also occur in a non-living organism. I suppose anything that can’t do that wouldn’t stand much of a chance of survival.”