Comment

Comment by Dr. Krishna Kumari Challa on February 28, 2023 at 11:29am

Researchers discover the mechanism by which tumor cells become resistant to chemotherapy in colorectal cancer

 Platinum-based chemotherapy, which is used to treat advanced colorectal cancer, accumulates in the healthy cells surrounding the cancer cells and, as a result, can reduce tumor sensitivity to treatment. This is demonstrated by a study published in the journal Nature Communications.

 A large number of cancer patients are treated with platinum-based therapy. However, many tumors are capable of developing resistance to treatment. In this study, the researchers examined tumor samples from patients and pre-clinical models of colorectal cancer to better understand the resistance to platinum-based therapy. They observed that platinum accumulates prominently in the healthy cells that surround the cancer cells, particularly in fibroblasts, the cells that contribute to tissue formation. Furthermore, this accumulation persists for more than two years after treatment has been completed. This discovery was made using techniques developed in geology and applied to biological samples.

The effect of platinum on fibroblasts
The researchers were able to demonstrate how the accumulation of platinum in the fibroblasts induced the activation of certain genes associated with a poor response to chemotherapy and tumor progression. Among them, the TGF-β protein redirected these fibroblasts to support cancer cells aggressiveness and resistance to treatment. 

There are currently no predictive biomarkers of benefit from chemotherapy in colorectal cancer. The analysis of about thirty patients before and after chemotherapy presented in this study reveals that periostin levels are an indicator of TGF-β activity in fibroblasts and serve as a robust marker of response to chemotherapy. Indeed, treatment benefit was significantly reduced in patients with elevated periostin levels before and/or after chemotherapy. Accordingly, chemotherapy was found to be less effective in tumors with high levels of periostin in pre-clinical colorectal cancer models.

The researchers are now working on developing a novel approach to improve the efficacy of chemotherapy in colorectal cancer.

This study is an important step toward understanding why chemotherapy does not work the same way in all cancer patients, and how to prevent or reverse resistance. This work is also essential in demonstrating that cancer treatment must take into account not only the cancer cells but also the healthy cells in the tumor. The next critical step will be to develop pharmacological strategies that act on the cancer cell and modulate the microenvironment in favor of tumor elimination.

 Jenniffer Linares et al, Long-term platinum-based drug accumulation in cancer-associated fibroblasts promotes colorectal cancer progression and resistance to therapy, Nature Communications (2023). DOI: 10.1038/s41467-023-36334-1

Comment by Dr. Krishna Kumari Challa on February 28, 2023 at 8:54am

Tiny environmental plastic particles in mom's food reach unborn children

Nanoscale plastic particles like those that permeate most food and water pass from pregnant rats to their unborn children and may impair fetal development, according to a  study that suggests the same process happens in humans.

Erosion chips microscopic particles off the billions of tons of plastics that are exposed to the elements in the environment. These particles mix with the food we eat and the air we breathe. A typical person ingests a credit card's worth of them every week.

Previous studies in pregnant laboratory animals have found adding these plastics to food impairs their offspring in numerous ways, but those studies didn't determine whether mothers passed the plastics to their children in utero.

The study provided specially marked nanoscale plastics to five pregnant rats. Subsequent imaging found that these nanoplastic particles permeated not only their placentas but also the livers, kidneys, hearts, lungs and brains of their offspring.

These findings demonstrate that ingested nanoscale polystyrene plastics can breach the intestinal barrier of pregnant mammals, the maternal-fetal barrier of the placenta and all fetal tissues. Future studies will investigate how different types of plastics cross cell barriers, how plastic particle size affects the process and how plastics harm fetal  development, the researchers said.

 Chelsea M. Cary et al, Ingested Polystyrene Nanospheres Translocate to Placenta and Fetal Tissues in Pregnant Rats: Potential Health Implications, Nanomaterials (2023). DOI: 10.3390/nano13040720

Comment by Dr. Krishna Kumari Challa on February 28, 2023 at 8:48am

Study finds common artificial sweetener linked to higher rates of heart attack and stroke

New research showed that erythritol, a popular artificial sweetener, is associated with an increased risk of heart attack and stroke. Findings were published today in Nature Medicine.

Researchers studied more than 4,000 people in the U.S. and Europe and found those with higher blood erythritol levels were at elevated risk of experiencing a major adverse cardiac event such as heart attack, stroke or death. They also examined the effects of adding erythritol to either whole blood or isolated platelets, which are cell fragments that clump together to stop bleeding and contribute to blood clots. Results revealed that erythritol made platelets easier to activate and form a clot. Pre-clinical studies confirmed ingestion of erythritol heightened clot formation.

Artificial sweeteners, such as erythritol, are common replacements for table sugar in low-calorie, low-carbohydrate and "keto" products. Sugar-free products containing erythritol are often recommended for people who have obesity, diabetes or metabolic syndrome and are looking for options to help manage their sugar or calorie intake. People with these conditions also are at higher risk for adverse cardiovascular events like heart attack and stroke.

Erythritol is about 70% as sweet as sugar and is produced through fermenting corn. After ingestion, erythritol is poorly metabolized by the body. Instead, it goes into the bloodstream and leaves the body mainly through urine. The human body creates low amounts of erythritol naturally, so any additional consumption can accumulate.

Measuring artificial sweeteners is difficult and labeling requirements are minimal and often do not list individual compounds. Erythritol is "Generally Recognized As Safe (GRAS)" by the FDA, which means there is no requirement for long-term safety studies.

The authors note the importance of follow-up studies to confirm their findings in the general population. The study had several limitations, including that clinical observation studies demonstrate association and not causation.

This study shows that when participants consumed an artificially sweetened beverage with an amount of erythritol found in many processed foods, markedly elevated levels in the blood are observed for days—levels well above those observed to enhance clotting risks. It is important that further safety studies are conducted to examine the long-term effects of artificial sweeteners in general, and erythritol specifically, on risks for heart attack and stroke, particularly in people at higher risk for cardiovascular disease.

 Stanley Hazen, The artificial sweetener erythritol and cardiovascular event risk, Nature Medicine (2023). DOI: 10.1038/s41591-023-02223-9. www.nature.com/articles/s41591-023-02223-9

Comment by Dr. Krishna Kumari Challa on February 28, 2023 at 8:41am

Tissue engineering: Developing bioinspired multi-functional tendon-mimetic hydrogels

Materials scientists work to develop advanced biological materials for medical devices and tissue engineering platforms to emulate natural biological tissue architectures via materials engineering. However, the natural tissue architecture has a variety of characteristics that are difficult to synthetically replicate. The architecture of tendons relies on the load-bearing capacities of the musculoskeletal system to provide biophysical cues that translate into cellular behaviors via interfacial interactions. In the past decade, researchers had devoted extensive research efforts to engineer tendon-mimetic materials with high structural anisotropy.

In a new report now published in Science Advances,  a research team in physics, mechanical engineering, electrical and electronic engineering reported the development of multifunctional tendon-mimetic hydrogels by assembling aramid nanofiber composites. 

The anisotropic composite hydrogels (ACH) contained stiff nanofibers and soft polyvinyl alcohol moieties to mimic biological interactions that typically occur between collagen fibers and proteoglycans  in tendons. The team was bioinspired by natural tendons to develop hydrogels with a high elastic modulus, strength and fracture toughness.

The researchers biofunctionalized these material surfaces with bioactive molecules to present biophysical cues to impart behavioral similarities to those of cell attachment. Additionally, the soft bioelectronic components integrated on the hydrogels facilitated a variety of physiological benefits. Based on the outstanding functionality of the tendon-mimetics, the team envisioned broader applications of the materials in advanced tissue engineering to form implantable prosthetics for human-machine interactions.

Mingze Sun et al, Multifunctional tendon-mimetic hydrogels, Science Advances (2023). DOI: 10.1126/sciadv.ade6973

Jeong-Yun Sun et al, Highly stretchable and tough hydrogels, Nature (2012). DOI: 10.1038/nature11409

Comment by Dr. Krishna Kumari Challa on February 26, 2023 at 10:13am

Even to this day, however, it's still unclear how so many animals achieve these incredible feats of navigation.

In the 1970s, scientists suggested that this magnetic-compass sense could involve radical pairs, molecules with unpaired outer shell electrons that form a pair of entangled electrons whose spins are altered by the Earth's magnetic field.

Twenty-two years later, that study's lead author co-authored a new paper proposing a specific molecule in which the radical pairs could be formed.

This molecule – a receptor in the retina of migrating birds called a cryptochrome – can sense light and magnetism, and it seems to work through quantum entanglement.

In basic terms, when a cryptochrome absorbs light, the energy triggers one of its electrons, pushing it to occupy one of two spinning states, each of which is differently influenced by Earth's geomagnetic field.

Cryptochromes have been a leading explanation for how animals sense magnetic fields for two decades, but now researchers at the Universities of Manchester and Leicester have identified another candidate.

Manipulating the genes of fruit flies, the team found that a molecule called Flavin Adenine Dinucleotide (FAD), which usually forms a radical pair with cryptochromes, is actually a magnetoreceptor in and of itself.

This basic molecule is found at differing levels in all cells, and the higher the concentration, the more likely it is to impart magnetic sensitivity, even when cryptochromes are lacking.

In fruit flies, for instance, when FAD is stimulated by light, it generates a radical pair of electrons that are responsive to magnetic fields.

However, when cryptochromes are present alongside FADs, a cell's sensitivity to magnetic fields increases. The findings suggest that cryptochromes are not as essential as we thought for magnetoreception.

That shows cells can, at least in a laboratory, sense magnetic fields through other ways."

The discovery could help explain why human cells show sensitivity to magnetic fields in the lab. The form of cryptochrome present in the cells of our species' retina has proved capable of magnetoreception at a molecular level when expressed in fruit flies.

However, this doesn't mean humans utilize that function, nor is there evidence that cryptochrome guides our cells to line up along magnetic fields in the lab.

Even though human cells show sensitivity to Earth's magnetic field, we don't have a conscious sense of that force. Maybe that's because we don't have any cryptochromes assisting.

This study may ultimately allow us to better appreciate the effects that magnetic field exposure might potentially have on humans.

https://www.nature.com/articles/s41586-023-05735-z

Part 2

**

Comment by Dr. Krishna Kumari Challa on February 26, 2023 at 10:10am

All Living Cells Could Have The Molecular Machinery For a 'Sixth Sense'

Every animal on Earth may house the molecular machinery to sense magnetic fields, even those organisms that don't navigate or migrate using this mysterious 'sixth sense'.

Scientists working on fruit flies have now identified a ubiquitous molecule in all living cells that can respond to magnetic sensitivity if it is present in high enough amounts or if other molecules assist it.

The new findings suggest that magnetoreception could be much more common in the animal kingdom than we ever knew. If researchers are right, it might be an astonishingly ancient trait shared by virtually all living things, albeit with differing strengths.

That doesn't mean all animals or plants can actively sense and follow magnetic fields, but it does suggest that all living cells might, including ours.

How we sense the external world, from vision, hearing through to touch, taste, and smell, are well understood.

But by contrast, which animals can sense and how they respond to a magnetic field remains unknown. This study has made significant advances in understanding how animals sense and respond to external magnetic fields - a very active and disputed field.

Magnetoreception might sound like magic to us, but plenty of fish, amphibians, reptiles, birds, and other mammals in the wild can sense the tug of Earth's magnetic field and use it to navigate space.

Because this force is essentially invisible to our species, it took a remarkably long time for scientists to notice it.

Only in the 1960s did scientists show that bacteria can sense magnetic fields and orient themselves in relation to those fields; in the 1970s, we found that some birds and fish follow Earth's magnetic field when migrating.

Part 1

Comment by Dr. Krishna Kumari Challa on February 26, 2023 at 8:18am

Combining forces to advance ocean science

Comment by Dr. Krishna Kumari Challa on February 25, 2023 at 12:59pm

How scientists hauling logs on their heads may have solved a Chaco Canyon mystery!

Why did researchers carry a log weighing more than 130 pounds for 15 miles? Their feat of endurance could reveal new information about how ancient peoples hauled more than 200,000 heavy timbers to a site in the modern-day Southwest called Chaco Canyon.

In a new study, several researchers reenacted a small part of a trek that people in the Southwest United States may have made more than 1,000 years ago.

They described their experiment Feb. 22 in the Journal of Archaeological Science: Reports.

This is also done by sherpas in Nepal.

The researchers  they were hoping to solve an archaeological mystery that has perplexed researchers for decades: How did ancient peoples transport more than 200,000 heavy construction timbers over 60 miles to a famous site in the Southwest called Chaco Canyon?

The team's findings show that the key to this testament to human labor may have been simple devices called tumplines. These straps, which sherpas, or native mountain peoples of Nepal, still widely use today, loop over the top of the head. They help porters to support weight using the bones of their neck and spine rather than their muscles. Archaeological evidence suggests that ancient peoples in the Southwest employed tumplines woven from yucca plants to transport everyday items like food and water.

Tumplines allow one to carry heavier weights over larger distances without getting fatigued.

Chaco Canyon sits near the border between New Mexico and Colorado. Thousands of people, the ancestors of today's Diné, or Navajo, and Pueblo peoples, may have lived there from around A.D. 850 to 1200. They built "Great Houses," which were as much as four stories tall and contained hundreds of rooms.

But how this society got its construction supplies has been a long-standing mystery. Human porters would have needed to carry 16-foot-long wooden beams to Chaco Canyon by foot—following a network of ancient roads to sites like the Chuska Mountains to the west.

The team's findings open up a new understanding of the day-to-day lives of the people who shaped the Southwest more than a thousand years ago.

the team's results show that supplying Chaco Canyon with goods may not have been as back-breaking an undertaking as archaeologists once assumed.

As these guys showed, you don't have to be super trained to carry a log.

ames A. Wilson et al, Were timbers transported to Chaco using tumplines? A feasibility study, Journal of Archaeological Science: Reports (2023). DOI: 10.1016/j.jasrep.2023.103876

Comment by Dr. Krishna Kumari Challa on February 25, 2023 at 12:19pm

How birds got their wings

Modern birds capable of flight all have a specialized wing structure called the propatagium without which they could not fly. The evolutionary origin of this structure has remained a mystery, but new research suggests it evolved in nonavian dinosaurs. The finding comes from statistical analyses of arm joints preserved in fossils and helps fill some gaps in knowledge about the origin of bird flight.

Comment by Dr. Krishna Kumari Challa on February 25, 2023 at 11:17am

Young adult mice with brain injury were injected with a substance which permanently labeled astrocytes in red and knocked out the function of a gene called p53—known to have a vital role in suppressing many different cancers. A control group was treated the same way, but the p53 gene was left intact. A second group of mice was subjected to p53 inactivation in the absence of injury.

Normally astrocytes are highly branched—they take their name from stars—but what we found was that without p53 and only after an injury the astrocytes had retracted their branches and become more rounded. They weren't quite stem cell-like, but something had changed. So scientists let the mice age, then looked at the cells again and saw that they had completely reverted to a stem-like state with markers of early glioma cells that could divide.

This suggested that mutations in certain genes synergized with brain inflammation, which is induced by acute injury and then increases over time during the natural process of aging to make astrocytes more likely to initiate a cancer. Indeed, this process of change to stem-cell like behavior accelerated when they injected mice with a solution known to cause inflammation.

The team then looked for evidence to support their hypothesis in human populations. They consulted electronic medical records of more than 20,000 people who had been diagnosed with head injuries, comparing the rate of brain cancer with a control group, matched for age, sex and socioeconomic status.

They found that patients who experienced a head injury were nearly four times more likely to develop a brain cancer later in life, than those who had no head injury. It is important to keep in mind that the risk of developing a brain cancer is overall low, estimated at less than 1% over a lifetime, so even after an injury the risk remains modest.

We know that normal tissues carry many mutations which seem to just sit there and not have any major effects. These new  findings suggest that if on top of those mutations, an injury occurs, it creates a synergistic effect.

In a young brain, basal inflammation is low so the mutations seem to be kept in check even after a serious brain injury. However, upon aging, the mouse work suggests that inflammation increases throughout the brain but more intensely at the site of the earlier injury. This may reach a certain threshold after which the mutation now begins to manifest itself.

Simona Parrinello, Injury primes mutation bearing astrocytes for dedifferentiation in later life, Current Biology (2023). DOI: 10.1016/j.cub.2023.02.013. www.cell.com/current-biology/f … 0960-9822(23)00152-5

Part 2

• ‹ Previous
• 1
• …
• 182
• 183
• 184
• 185
• 186
• …
• 847
• Next ›
• Page