Striped Denmark (Denmark rerio), zebrafish. Credit: Blue.
Some trials are not possible on humans. This is why researchers are so popular with experimental organisms. One of the common, unresponsive "volunteers" we owe a lot to is Denmark's striped water fish. Scientists at Duke University also experiment with fish, in English literature described as zebra fish. The reason is their ability to regenerate damaged body tissue. It has long been thought that regeneration occurs by dividing heart muscle cells – those found in the immediate vicinity of the site of injury.
Duke University is a private university in Durham, North Carolina. In the "Expert Related Factories" studies, he and the Massachusetts Institute of Technology are seventh among the highest educational and research institutions in the United States. Image is the University Chapel.
At Duke University, however, they found that many undefined stellate cells arrived at the site of the wound and packed into a suitable area (regenerative mouth, blastema). Then it is transformed into heart muscle cells and the heart is elegantly regenerated. Apparently, a key signal to regenerate stem cells is sent by the membrane cells surrounding the heart (epicardium). After 14 days, the wounds with fibroblast growth factor contribution are targeted. From a future practical point of view, it is important to conclude from these experiments that this ability to regenerate was a common ancestor of all vertebrates, only some of the offspring lost it.
A series of images reveals how epithelial cells begin to shed their unwanted colleague due to destruction due to too much "chemistry." Within ten minutes it was over. Credit: John Rawls Lab, Duke University.
Denmark is not just a promising model for treating heart attacks. A few days ago, a team of molecular geneticists described in the Proceedings of the American Academy of Sciences the discovery of a remarkable defense mechanism that pulls us from toxic disasters. Such as, for example, pharmacologically induced enteropathy. Translated into human language: when it comes to poisoning too many drugs with harmful side effects.
For decades, it has been thought that if toxins enter the intestine, they will destroy the mucous membranes, and their cells will leak and go away with the yeast. It is described as delamination and as something that must be prevented to maintain our health. The reality of delamination is different. It is true that in some poisonings, mucosal cells begin to peel as a race, but as has been shown now, this applies only to "selected" intestinal cells and labeled with a certain protein. It is not a toxic substance, but surface protein somehow ensures that some of the cells become unpopular in the collective and it expels them from their ranks. This holds true for the "burger" cells that have sucked the ruthless into their intestines more than healthy. If these cells were left alive where they were and the cousins would not release them, the toxic substance would flood and poison the entire body.
There may be some furiantism and altruism in the calibration of cells with a specific protein. Maybe the cells themselves voluntarily decide to take on the role of savior and purposely fill themselves with as much harm as possible to calm the whole thing at the expense of suicide. Whatever the case, it is important that this type of apoptosis works not only in fish but also in our country.
The cross section of the intestine shows a relationship between epithelial cells (stained in green) and absorption cells (intended to be destroyed) expressing the protein (stained in red). Credit: John Rawls Lab, Duke University.
Sinful pushing of intestinal cells is not what we had it for. It does not hurt and does not need to be prevented. The opposite is true, it is a complex defense tool that can remove us, not "from all evil" but from a few toxins. An example is the calm substance Glaphenin. The use of this preparation has been very popular in Europe for three decades. But now it is withdrawn due to kidney and liver damage. Indeed, many of us are indebted to the mechanism of delamination that we have undergone in the treatment. with this non-steroidal anti-inflammatory drug.
How does it work?
The intestinal lining consists of a single layer of tightly bound rod cells. It is so thin that nutrient penetration is as easy as possible. A large intestine, like inflammation, ceases to be an executive organ and wastes food. In order for the thin layer of mucosal cells to withstand any attack, the cells are firmly held together and secured to the ground by solid anchor proteins. When one becomes a "poisonous cup," her healthier colleagues push her and somehow force her to anchor – her binding proteins are released and tightened. The convict starts pushing her neighbors out of her community when she pushes her out of her community, giving her a death sentence in an out-of-pocket waste.
What makes this device interesting?
For example, it is a solution in situations where side effects of drugs (as in the case of Glafenin) stop the so-called outflow pumps. It works so well that they remove pollutants from the cells. Getting into the secrets of effluent pumps is a good thing. It may be useful in cases where it is desirable to intentionally reduce their performance. For example, in situations where chemotherapy is applied, from which we have to do a brief trial with cancer. The problem is that only perverted cells can often increase the performance of their outflow pumps and thus withstand even such poisonous cocktails that healthy cells cannot pump out of the body. Scientists acknowledge that they still do not know which of the intestinal mucosa cells are leaving, and in which direction it is going. However, their knowledge can be useful for better understanding poisoning, fighting allergies and possibly cancer.
Scott T. Espenschied, et al .: Epithelial delamination is protective during pharmacy-induced enteropathy, PNAS first published August 7, 2019 https://doi.org/10.1073/pnas.1902596116