Brain repair after stroke with injectable treatment

New injectable treatment helps the immune system to promote Brain repair 

An injectable biomaterial helped stroke-damaged brains recruit immune cells, regrow blood vessels, and restore movement in mice. Duke researchers developed an injectable scaffold which helped stroke-damaged brains grow new blood vessels, support nerve regrowth and recover movement in mice. The treatment appears to work partly by recruiting the body’s own immune cells, including neutrophils which may switch from damaging to helpful under the right conditions. Millions of people experience ischemic strokes each year. These strokes occur when a blood clot blocks blood flow to part of the brain. Biomedical engineers at Duke University have created an injectable biomaterial which may help the brain recover from damage left behind by an ischemic stroke. In experiments with mice, the material transformed the cavity created by lost brain tissue into a more favorable environment for healing. The treatment recruited the body's own immune cells, encouraged the formation of new blood vessels, supported changes in neural tissue, and improved motor function in the animals. The findings were published in Cell Biomaterials. Emergency treatments such as clot-dissolving drugs and procedures which physically remove the clot can restore circulation and help save brain tissue that is still viable. However, once brain tissue has died, restoring blood flow cannot replace what has already been lost. Severe strokes can destroy substantial amounts of tissue, leaving a cavity where healthy brain tissue once existed. After doctors remove the clot, recovery depends largely on rehabilitation. Rehabilitation can help surviving brain circuits adapt, but it does not directly rebuild the damaged region.

Delivered more than 24 hours after a stroke in mice, the biomaterial promoted vascular repair, neural remodeling and improved motor performance two-photon imaging at day 27 using Ly6G-green fluorescent protein (GFP) reporter mice to visualize neutrophils. IL-4/C1q-EV + MAPS implants exhibited dense vascularization and focal accumulation of GFP+ cells within scaffold pores. Injectable biomaterial that helps transform the cavity left behind after a stroke caused by a blood clot into an environment more supportive of repair. "Once brain tissue has been lost, restoring blood flow is no longer enough," said Tatiana Segura, the Robert Plonsey Distinguished Professor of Biomedical Engineering at Duke. "Our goal is to engineer the injured space so that immune, vascular and neural repair processes can begin to work together." Every year, millions of people experience strokes caused by blood clots, called ischemic strokes. Immediate treatments, including clot-dissolving drugs and mechanical removal of the clot, can restore blood flow and preserve threatened brain tissue. But these treatments cannot replace tissue that has already been lost. Large strokes can result in substantial tissue loss and leave behind a cavity at the site of the injury. After the clot is removed, recovery relies largely on rehabilitation, which helps surviving brain circuits adapt but does not directly repair the damaged area.

Segura and her team sought to create an environment inside the stroke cavity which could support several types of repair at once. They used MAPS, or microporous annealed particle scaffolds. These scaffolds consist of individual hydrogel microparticles that assemble into a porous structure. The open spaces provide cells with a framework they can enter and use while rebuilding neural tissue. Building on earlier successes with the biomaterial, the researchers wanted to determine whether they could also use the body's immune system to guide and strengthen the repair process. To pull in helpful immune cells, the team turned to astrocytes, star-shaped cells that support normal brain function and respond rapidly to injury. Astrocytes communicate with other cells in part by releasing extracellular vesicles, or EVs, which are nanoscale packages that carry proteins, lipids and genetic material. Once brain tissue has been lost, restoring blood flow is no longer enough. Main goal is to engineer the injured space so that immune, vascular and neural repair processes can begin to work together. The researchers collected EVs from lab-grown astrocytes and experimented with adding various signaling molecules to attract immune cells and promote vascular repair and functional improvement. Rather than simply injecting the EVs, the team used a chemical reaction to anchor them to the surfaces of the hydrogel microparticles. This kept the signals localized within the scaffold, where incoming cells could encounter them.

“We are not simply placing a material into the brain,” Segura said. “We are engineering a local environment that can coordinate several parts of the repair response.” One signaling combination stood out. IL-4 and C1q were particularly effective at drawing potentially helpful immune cells into the injured region. Those cells included macrophages as well as a surprisingly persistent population of neutrophils. Neutrophils are often linked to inflammation and tissue damage during the early stages of a stroke. The new results suggest their role may be more complicated. At a later point after injury, and when surrounded by the right signals and material environment, neutrophils may instead help support tissue repair. Researchers tested their importance by reducing the neutrophil-rich immune-cell population. When they did so, blood vessel formation declined substantially and the scaffold underwent less remodeling. The result indicated that these immune cells were playing an important role in the healing response. "This result changes how we think about neutrophils after stroke," said Shangjing Xin, lead scientist of the study and a postdoctoral fellow in the Segura Laboratory. "Their role appears to depend on when they arrive, where they are located, and the signals they receive from their surroundings. Our study demonstrates a potential engineering strategy to recruit and retain these cells at the right time."

One combination of signaling molecules, IL-4 and C1q, proved best at attracting helpful immune cells into the damaged region, including macrophages and an unexpectedly persistent population of neutrophils. Neutrophils are commonly associated with inflammation and tissue damage during the early stages of stroke. But the study suggests that, at a later stage and within the right material environment, these cells can also contribute to repair. When the researchers depleted the neutrophil-rich immune-cell population, blood vessel growth and scaffold remodeling were markedly reduced. This finding showed that the cells were important contributors to the repair response. “This result changes how we think about neutrophils after stroke,” said Shangjing Xin, lead scientists of the study and a postdoctoral fellow in the Segura Laboratory. “Their role appears to depend on when they arrive, where they are located and the signals they receive from their surroundings. Our study demonstrates a potential engineering strategy to recruit and retain these cells at the right time.” The immune response was accompanied by the formation of blood vessels throughout the treated cavity. The researchers also observed increased axonal fibers, which are key structures in brain cells, within and around the damaged region. Mice receiving the optimized scaffold also performed better on a grid-walking test which measures errors in forelimb placement. By eight weeks, their performance was statistically indistinguishable from that of healthy control mice, and the improvement was sustained throughout the study.

Importantly, EVs delivered without the MAP scaffold did not produce comparable vascular repair. This result showed that the biomaterial was not simply carrying a therapeutic cargo. Its porous structure and ability to localize the EV signals were essential to the response. While these findings are a step in the right direction, the findings remain preclinical. The evolving treatment was tested in mouse models by directly injecting it into the damaged site. Additional studies will be required to evaluate its safety, determine how the different immune-cell populations contribute to recovery, and test the approach in larger and more clinically representative stroke models. The current study used EVs collected from primary rat astrocytes. As a next step, the Segura laboratory is exploring EVs produced by human induced pluripotent stem cell-derived astrocytes. This approach could provide a more scalable and clinically relevant source of EVs while allowing the researchers to better control the signals they carry. The researchers also tested whether the extracellular vesicles could produce similar effects without the biomaterial scaffold. They could not.

Despite the promising results, the approach remains preclinical. So far, researchers have tested the treatment in mouse models by injecting the material directly into the damaged area of the brain. Further research will be necessary to assess safety, understand precisely how different immune-cell populations influence recovery, and determine whether the treatment works in larger models that more closely resemble human stroke. The researchers also currently obtain the EVs from primary rat astrocytes. “You do not restore an ecosystem simply by containing the initial damage,” Segura said. “You have to create the conditions that allow life to return. That is how we think about the stroke cavity. The material is not intended to reproduce the brain itself, but to create an environment where the body’s own cells can enter, communicate and participate in rebuilding vascularized tissue.”

Safer, cheaper vision correction

 Vision correction without lasers or surgery, An alternative to LASIK 

Millions of Americans have altered vision, ranging from blurriness to blindness. But not everyone wants to wear prescription glasses or contact lenses. Accordingly, hundreds of thousands of people undergo corrective eye surgery each year, including LASIK, a laser-assisted surgery which reshapes the cornea and corrects vision. The procedure can result in negative side effects, prompting researchers to take the laser out of LASIK by remodeling the cornea, rather than cutting it, in initial animal tissue tests. Researchers are developing a futuristic alternative to LASIK which reshapes the eye without lasers or incisions. Using mild electrical pulses and platinum contact lenses, they temporarily soften the cornea so it can be molded into a new shape. Early tests on rabbit eyes successfully corrected nearsightedness in about a minute while preserving the eye’s structure.

Hundreds of thousands of people undergo corrective laser-based eye surgeries each year, but researchers are hoping to change that thanks to a corneal reshaping technique currently in development. Human corneas are dome-shaped, clear structures that sit at the front of the eye, bending light from surroundings and focusing it onto the retina, where it’s sent to the brain and interpreted as an image. But if the cornea is misshapen, it doesn’t focus light properly, resulting in a blurry image. With LASIK, specialized lasers reshape the cornea by removing precise sections of the tissue. This common procedure is considered safe, but it has some limitations and risks, and cutting the cornea compromises the structural integrity of the eye. Millions around the world live with blurry vision, nearsightedness or more severe sight problems. While glasses and contact lenses help many people, millions have turned to corrective procedures such as LASIK to sharpen their eyesight. But scientists are now exploring a very different approach which could someday reshape the eye without lasers, cutting or invasive surgery.

Researchers from Occidental College and the University of California, Irvine have been developing an experimental technique called electromechanical reshaping (EMR). Instead of carving away tissue like LASIK, the method temporarily softens the cornea so it can be gently molded into a new shape. Early tests in rabbit eyes suggest the technology may one day provide a cheaper, less invasive alternative to traditional laser eye surgery. The idea behind EMR emerged unexpectedly during earlier experiments involving cartilage and other collagen-rich tissues. "The whole effect was discovered by accident," explains Brian Wong, a professor and surgeon at the University of California, Irvine. "I was looking at living tissues as moldable materials and discovered this whole process of chemical modification." Collagen-rich tissues throughout the body, including the cornea, maintain their shape through networks of charged molecules which hold the structure together. Because these tissues contain large amounts of water, scientists found that applying a mild electric current can temporarily alter the tissue's acidity level, or pH. As the pH shifts, the molecular bonds holding the tissue rigid begin to loosen. This briefly makes the tissue flexible enough to reshape. Once the pH returns to normal, the tissue stiffens again and locks into its new form. Researchers had previously tested EMR on rabbit ear cartilage, pig skin and scar tissue. The cornea became one of the most promising targets because even small changes in its curvature can dramatically improve vision.

In the body, the shapes of many collagen-containing tissues, including corneas, are held in place by attractions of oppositely charged components. These tissues contain a lot of water, so applying an electric potential to them lowers the tissue’s pH, making it more acidic. The cornea is the clear, dome-shaped surface at the front of the eye. It bends incoming light and helps focus images onto the retina. When the cornea is too steep, too flat or unevenly shaped, vision becomes blurry. LASIK corrects those problems by using lasers to remove tiny amounts of corneal tissue and permanently reshape the eye. Although the procedure is widely used and generally considered safe, it can sometimes lead to complications including dry eyes, glare, halos and weakened corneal structure. Michael Hill, a chemistry professor at Occidental College, says the basic concept behind LASIK still comes down to tissue removal. "LASIK is just a fancy way of doing traditional surgery. It's still carving tissue -- it's just carving with a laser." This limitation inspired researchers to search for a way to reshape the cornea without making incisions at all.

In this work, the team constructed specialized, platinum “contact lenses” which provided a template for the corrected shape of the cornea, then placed each over a rabbit eyeball in a saline solution meant to mimic natural tears. The platinum lens acted as an electrode to generate a precise pH change when the researchers applied a small electric potential to the lens. After about a minute, the cornea’s curvature conformed to the shape of the lens, about the same amount of time LASIK takes, but with fewer steps, less expensive equipment and no incisions. The team tested the procedure on 12 rabbit eyeballs. Ten were treated to simulate correction for myopia, also known as nearsightedness. In those eyes, the corneas successfully achieved the intended focusing power which would correspond to improved vision. Importantly, the cells within the tissue remained alive because the researchers carefully controlled the pH changes during treatment.

The researchers also reported another intriguing possibility. In separate experiments, the same technique appeared capable of reversing some forms of chemical cloudiness in the cornea. Today, severe corneal clouding often requires a full corneal transplant. Scientists say EMR could potentially avoid some of the major drawbacks associated with LASIK and related procedures such as PRK. Because the method does not remove corneal tissue, it may preserve more of the eye's natural structural strength. The electromechanical reshaping technique successfully flattened rabbit cornea from its original shape to a corrected one. In all the “myopic” eyeballs, the treatment dialed in the targeted focusing power of the eye, which would correspond to improved vision. The cells in the eyeball survived the treatment, because the researchers carefully controlled the pH gradient. Additionally, in other experiments, the team demonstrated that their technique might be able to reverse some chemical-caused cloudiness to the cornea, a condition that is currently only treatable through a complete corneal transplant. Laboratory imaging studies using optical coherence tomography (OCT), confocal microscopy and second-harmonic generation microscopy also suggested that the cornea's collagen structure remained largely intact after treatment. Researchers reported no major loss of transparency or obvious tissue damage in the early experiments.

More recent reports and engineering updates have continued to refine the technology. Scientists are now developing advanced electrode contact lenses capable of monitoring corneal shape, hydration and transparency during treatment. Researchers have also explored whether EMR could eventually be adapted for conditions beyond nearsightedness, including farsightedness, astigmatism and certain reconstructive procedures involving cartilage-rich tissues. Some scientists believe the approach could ultimately become far less expensive than laser-based surgery because it may not require large, complex laser systems. Despite the excitement surrounding the technology, researchers caution that EMR remains highly experimental. This research was funded by the National Eye Institute of the National Institutes of Health and the John Stauffer Charitable Trust. Though this initial work is promising, the researchers emphasize that it is in its very early stages. Next up is the long march through animal studies that are detailed and precise including tests on a living rabbit rather than just its eyeball. They also plan to determine the types of vision correction possible with EMR, such as near- and far-sightedness and astigmatism. Though the next steps are planned, uncertainties in the team’s scientific funding have put them on hold. 

"There's a long road between what we've done and the clinic," concludes Hill. "But, if we get there, this technique is widely applicable, vastly cheaper and potentially even reversible." Researchers are also continuing to study how precisely the procedure can correct different types of vision problems and whether long-term side effects might emerge after treatment. For now, LASIK remains the standard option for surgical vision correction. But EMR has opened the door to a future where fixing blurry vision may no longer require lasers, cutting, or permanent tissue removal. The American Chemical Society (ACS) is a nonprofit organization founded in 1876. ACS is committed to improving all lives through the transforming power of chemistry. Its mission is to advance scientific knowledge, empower a global community and champion scientific integrity, and its vision is a world built on science. The Society is a global leader in promoting excellence in science education and providing access to chemistry-related information and research through its multiple research solutions. As a leader in scientific information solutions, its CAS division partners with global innovators to accelerate breakthroughs by curating, connecting and analyzing the world’s scientific knowledge. 

The Great Pacific Garbage Patch

 The largest accumulation of ocean plastic in the world, Great Pacific Garbage Patch 

The Great Pacific Garbage Patch is the largest accumulation of ocean plastic in the world and is located between Hawaii and California. Scientists of The Ocean Cleanup have conducted the most extensive analysis ever of this area. Every minute, more than 3,300* kilograms of plastic enter the ocean. It is the largest of the five offshore plastic accumulation zones in the world’s oceans and located halfway between Hawaii and California in the Pacific Ocean. When we picture the open Pacific, it is supposed to be only blue water. Marine researchers, however, are now seeing something very different: places like the Great Pacific Garbage Patch where plastic waste has built a kind of artificial shoreline far from any land. In the North Pacific Subtropical Gyre, the huge rotating current system between California and Hawaii, floating objects tend to get trapped instead of drifting away. That’s where you find what people commonly call the Great Pacific Garbage Patch, a region which now holds tens of thousands of tons of plastic pieces sturdy enough to move around the ocean for years at a time. It is estimated that 1.15 to 2.41 million tonnes of plastic are entering the ocean each year from rivers. More than half of this plastic is less dense than the water, meaning that it will not sink once it encounters the sea. The stronger, more buoyant plastics show resiliency in the marine environment, allowing them to be transported over extended distances. They persist at the sea surface as they make their way offshore, transported by converging currents and finally accumulating in the patch. Once these plastics enter the gyre, they are unlikely to leave the area until they degrade into smaller microplastics under the effects of sun, waves and marine life. As more and more plastics are discarded into the environment, microplastic concentration in the Great Pacific Garbage Patch  will only continue to increase.

For a long time, biologists treated coastal waters and the open ocean as two separate neighborhoods. Coastal species were expected to stay on rocks, piers and shorelines, while pelagic species were the ones that belonged offshore. People knew that a storm could knock a log or a raft of seaweed loose and carry coastal organisms away from land, but the usual assumption was that those passengers would eventually die because conditions in the open ocean are too harsh. A big clue that this view was incomplete came after the Great East Japan Tsunami. The huge waves ripped loose docks, boats and many plastic objects and sent them drifting into the Pacific. For years afterward, pieces of that debris landed on beaches in North America and Hawaii. When scientists checked those objects, they found that many Japanese coastal species had stayed alive on them for at least six years as they crossed the ocean. This led to a new question: were these coastal species only passing through the open ocean, or were they beginning to form more permanent communities there? The GPGP covers an estimated surface area of 1.6 million square km's, an area twice the size of Texas or three times the size of France. Due to seasonal and interannual variabilities of winds and currents, the GPGP’s location and shape are constantly changing. Only floating objects which are predominantly influenced by currents and less by winds were likely to remain within the patch. By simulating concentration levels in the North Pacific, the researchers were able to follow the location of the patch, demonstrating significant seasonal and interannual variations. On average the patch orbits around 32°N and 145°W. However, the team observed seasonal shifts from west to east and substantial variations in latitude (North to South) depending on the year.

To explore, scientists joined research cruises to the eastern side of the gyre. Standing on deck, crew members watched the sea surface and picked out plastic items at least 6 inches (15 cm's) long. In the end they brought on board 105 pieces of floating plastic, including bottles, buoys, crates, nets, ropes and buckets, along with a “wildcard” group of especially life‑covered objects. Every item was labeled, photographed and tagged with its position before being set aside for careful study back in the lab. Back in the laboratory, taxonomists went through each piece of plastic and looked for invertebrates, animals without backbones. They found a wide variety of creatures, such as barnacles, crabs, amphipods, bryozoans, hydroids and sea anemones. Altogether they identified 46 different kinds of invertebrates from six major animal groups. Of those 46, 37 were coastal species and 9 were pelagic, which means roughly 80% of the diversity on the debris came from coastal organisms. At the time of sampling, there were more than 1.8 trillion pieces of plastic in the patch that weigh an estimated 100,000 tonnes. These figures are 4-16 times more than previous calculations. This weight is also equivalent to more than 740 Boeing 777s. The center of the GPGP has the highest density and the further boundaries are the least dense. A plastic count that is equivalent to 250 pieces of debris for every human in the world. Using a similar approach as they did when figuring the mass, the team chose to employ conservative estimations of the plastic count. While 1.8 trillion is a mid-range value for the total count, their calculations estimated that it may be range from 1.1 to up to 3.6 trillion pieces. Using data from multiple reconnaissance missions, a mass concentration model was produced to visualize the plastic distribution in the patch. The mass concentration model shows that the center concentration levels contain the highest density, reaching 100s of kg/km² while decreasing down to 10 kg/km² in the outermost region.

Interestingly, pelagic communities were strongly linked to the type of plastic object, while coastal communities were more tied to when the debris was collected during the cruises. The researchers then compared these gyre communities with earlier work on debris from the 2011 tsunami. Many of the coastal species found on plastics in the gyre had also been seen on Japanese tsunami debris. However, the groups that were most diverse were not exactly the same, and some coastal groups, such as mollusks, were much less common in the gyre. Overall, the gyre debris supported fewer species than the tsunami debris, and the researchers’ analyses suggested that there are probably still coastal species living on plastics in the gyre which scientists have not yet recorded. Results of these expeditions proved that the buoyant plastic mass is distributed within the top few meters of the ocean. Factors such as wind speed, sea state and plastic buoyancy will influence vertical mixing. However, buoyant plastic will eventually float back to the surface in calmer seas. Larger pieces were observed to resurface much more rapidly than smaller pieces. Characteristics of the debris in the Great Pacific Garbage Patch, such as plastic type and age, prove that plastic has the capacity to persist in this region. Plastic in the patch has also been measured since the 1970’s and the calculations from subsequent years show that microplastic mass concentration is increasing exponentially, proving that the input of plastic in the patch is greater than the output. Unless sources are mitigated, this number will continue to rise.

One of the biggest questions was whether coastal organisms were just temporary passengers on the plastic or whether they could live out their whole life cycles there. The team looked for evidence of reproduction and growth. They searched for brooding females, as they carrying eggs or young, in several crustacean groups such as amphipods and crabs, and they did find them. They also saw reproductive structures on hydroids. The scientists also measured individual animals and noted the range of sizes on each piece of debris. On some species of sea anemones and amphipods they saw tiny juveniles, medium‑sized individuals and full‑grown adults all living together on the same plastic surface. The pattern suggests that new generations were growing up on these rafts instead of all arriving at the same time from the coast. When the team checked the plastic, almost every piece they had picked up was carrying life, mostly invertebrates. Invertebrates were present on 98% of the objects. Pelagic species showed up on more than 94% of the pieces, and coastal species on a bit over 70%. Many items hosted both coastal and pelagic species at the same time, so these very different organisms were sharing the same floating “islands” in the middle of the ocean. On average, each plastic item carried about four to five kinds of organisms, and coastal species were slightly more common than pelagic ones. Nets and ropes tended to have especially dense communities, probably because their many strands and small spaces offered plenty of places to hang on and hide. The vast majority of plastics retrieved were made of rigid or hard polyethylene (PE) or polypropylene (PP), or derelict fishing gear. Ranging in size from small fragments to larger objects and meter-sized fishing nets. When accounting for the total mass, 92% of the debris found in the patch consists of objects larger than 0.5 cm, and three-quarters of the total mass is made of macro- and mega plastic. However, in terms of object count, 94% of the total is represented by microplastics. Once the plastics were collected, classified the plastic into:

Hard plastic, plastic sheet or film

Plastic lines, ropes, and fishing nets

Pre-production plastics (cylinders, spheres or disks)

Fragments made of foamed materials

These plastic types were then screened for clues on age and origin. This was performed by examining each object for dates, languages, trademarks, symbols or ‘made in’ statements.

Because the plastics have been shown to persist in this region, they will likely break down into smaller plastics while floating in the GPGP. This deterioration into microplastics is usually the result of sun exposure, waves, marine life and temperature changes. Microplastics have been discovered floating within the water surface layers, but also in the water column or as far down as the ocean floor. Once they become this small, microplastics are very difficult to remove and are often mistaken for food by marine animals. To understand why some species handle this lifestyle better than others, the researchers looked at traits which might be useful on a plastic raft. They noted whether adults stayed fixed in place (sessile) or could move around, and they recorded how each species fed, for example, by filtering particles from the water, grazing on surfaces, hunting prey or using more than one of these methods. Many of the coastal species living on the plastic were able to reproduce asexually, essentially cloning themselves. Their larvae also did not need to spend much time drifting freely in the water. Young animals could grow right on the same surface as the adults. This kind of life cycle fits well with a small, isolated raft of plastic that slowly circles within the gyre. Taken together, these results point to the rise of a “neopelagic” community in the open ocean, where “neo” means new and “pelagic” refers to life in the open sea. This neopelagic community includes both the usual pelagic rafters and coastal species which can now survive far from land because plastic items act as durable homes.

In the past, one big reason coastal species stayed near shore was the lack of long‑lasting, floating hard surfaces in the open ocean. Human‑made plastics have changed that by adding countless new floating “islands” for coastal life in waters that used to be almost entirely pelagic. Plastic pollution is, therefore, not only an eyesore or a trash problem; it also shifts where marine life can live and allows coastal organisms to survive, reproduce and spread across huge distances. This discovery may reshape marine ecosystems and species ranges around the world. The finding confirms that stopping plastic inflow from land and river will not be enough to stop the GPGP to grow, we need to work with policy makers to find a binding agreement on the use of plastic in the industry. Not only does plastic pollution in the Great Pacific Garbage Patch pose risks for the safety and health of marine animals, but there are health and economic implications for humans as well. Studies have shown that about 900 species have encountered marine debris, and 92% of these interactions are with plastic. 17% of the species affected by plastic are on the IUCN (International Union for Conservation of Nature) Red List of Threatened Species.

A peer-reviewed study assessed the environmental impact of removing plastic from the Great Pacific Garbage Patch. The findings from this collaborative research between our in-house experts and independent scientists highlighted that the benefits of cleaning the GPGP outweighed potential environmental costs, including greenhouse gas emissions and ecosystem disruptions from carrying out the cleanup. The study states that the findings show that marine life is more vulnerable to plastic pollution than to our offshore cleanup efforts. Not only is the size and count of the plastic in the GPGP important to calculate, but the way in which the plastic interacts in the water helps the team learn more about the buoyancy and depths of the plastic. It is commonly known that harmful PBT (Persistent Bio-accumulative Toxic) chemicals are found in ocean plastics, so researchers at The Ocean Cleanup tested plastic samples from the expeditions for their chemical levels. Their results helped them to realize what chemicals are present in the patch and what that means for animals feeding there. Plastics ranging from various type and size were analyzed by placing them in mixtures which would allow the various chemicals to be identified. A process known as Chromatography. They found through various tests that 84% of the plastics in the GPGP contain at least one type of PBT chemical. More research will be required in order to discover if this also applies to the other garbage patches around the world.

Importance of Human Eyebrows

 Reasons for having Eyebrows

Most people think far more about how their eyebrows look than what they do. Despite all of our plucking, waxing, shaping, or re-drawing them into place, our eyebrows are specifically designed for function rather than form. Your eyebrows serve an essential function when it comes to eye and vision health: they are one of your eyes’ first means of protection. From rigid brow ridges to expressive arches, your eyebrows tell a story of how human faces evolved to signal emotion, identity and social intent. We tend to forget that our eyebrows are even there. They sit above the eyes, doing their work without much fanfare, until, of course, they’re gone. Shave them off, and your face becomes strangely unfamiliar, if not totally unplaceable. This disturbance tells us that our eyebrows are doing far more work for us than we consciously note. For a long time, the standard explanation for their existence was straightforward. Eyebrows help keep sweat and debris out of the eyes. But in evolutionary biology, explanations that feel obvious often turn out to be incomplete. And when researchers began to look more closely at eyebrows, a richer picture emerged.

One way to think of your eyebrows is that they are nature’s sweatband. Have you ever had sweat drip into your eyes? The acid in sweat burns the eyes and causes irritation. If you’re sweating enough, without a means to wipe it away, steady drops of sweat cause you to blink rapidly and may also cause blurred or obstructed vision. Since sweat runs from your scalp and down your forehead, like mini rivers or streams, it also carries dirt, bacteria and other particulates along with it. The curved eyebrow arch is no coincidence, either. The curve wicks the moisture off the skin and around the arch, helping it drain along the sides of your face. Without eyebrows, all of this would run right into your eyes. Fortunately, your eyebrows serve as a “sweatband,” helping to block the flow of sweat and lift it off of your face where it can evaporate before it gets to your eyes. In addition, this action of wicking and lifting up of sweat also serves as a cooling function! Combine fossil evidence, facial anatomy and experimental psychology, and it becomes clear that our eyebrows do so much more than simply protect our eyes. To understand eyebrows, we need to start with a broader shift in human evolution, during which the face itself underwent a full transformation. Early hominins (think Homo heidelbergensis or Neanderthals) had faces that looked very different from ours. Their most striking feature was a pronounced, continuous brow ridge: a thick bar of bone sitting above the eyes. This structure likely already provided substantial protection, helping shield the eyes from debris and mechanical stress. In that sense, the basic “protective” role often attributed to eyebrows was, to a large extent, already accounted for by the brow bone.

The most compelling answer for the purpose of the eyebrows comes from a 2018 study, which reframes the human face as a tool for social communication. The reduction of the brow ridge reflects a transition in how early humans interacted. Earlier hominins’ prominent brow ridges may have served as a signal of dominance or aggression, albeit a relatively static cue. But modern humans, by contrast, rely heavily on dynamic signals and eyebrows are central to that system. Consider how much information a slight eyebrow movement can convey:

A furrow signals concern or confusion

A long raise signals shock

An asymmetrical lift signals skepticism

A quick raise signals recognition or greeting

These are fast and low-effort signals, and they travel well across distance and lighting conditions. Importantly, they’re also difficult to fake convincingly, which makes them useful in maintaining trust within social groups. Modern humans took a different path. In an early study, researchers document a coordinated set of changes in Homo sapiens, namely:

The retraction of the midface (the area around the nose and cheeks)

The reduction of the brow ridge

Beyond largely altering our appearance, these changes also fundamentally reshaped the functional landscape of the face. With the heavy brow ridge reduced, the soft tissue above the eyes gained a wider range of visible motion. Eyebrows could lift, knit and arch in ways that were previously constrained.

In addition to protecting your eyes from sweat, the eyebrows also serve as a filter. They catch particulate matter from dropping into your eyes or further down onto your face. Many of these particulates are very small and almost invisible to the naked eye, making it hard to believe that eyebrows are as necessary as they are. However, without your eyebrows filtering these particles away from your eyes, you’d be far more susceptible to eye allergies and infections. To be clear, eyebrows still offer moderate protection. Their shape and hair direction help channel sweat away from the eyes and catch small particles. But compared to the robust shielding once provided by a protruding brow ridge, this role appears secondary. It’s more of a retained benefit than the primary evolutionary driver. Notably, eyebrows are part of a much broader pattern of changes; they weren’t the product of an isolated tweak. Study emphasizes that increased eyebrow mobility accompanied broader facial reconfiguration. As the mid face retracted, the upper face became more open, visible, and dynamic. These changes include:

The emergence of the chin, a uniquely human feature, which may contribute to facial structure and possibly social signaling, though its function remains debated. 

The whitening of the sclera (the whites of the eyes), which makes gaze direction unusually easy to track compared to other primates.

And the eyebrows, now freed from the constraints of a heavy brow ridge, which became highly mobile and visually prominent.

These features form a coordinated system: a face that can be interpreted. But that kind of coordinated change usually signals a shift in function. Hence, the question then becomes: What new role requires a more expressive upper face? Today, most of us wear sunglasses to protect our eyes from harmful UV rays. However, sunglasses have only been around for about four hundred years. Prior to that, humans relied on hats, the shade, their hands and their eyebrows to help shield the eyes from direct sunlight.

Earlier study situates this within a broader evolutionary trend toward increased cooperation and social tolerance. That is, as human groups grew larger and more interdependent, the ability to communicate subtle emotional states became more valuable. Faces that could signal emotions, rather than just dominance, would have had an advantage. Our eyebrows are part of a redesigned interface, in which we switched from having imposing faces to readable faces. The eyebrows are an essential part of human biology. Yes, they still perform a basic protective role. Their shape and position help divert sweat and debris away from the eyes. That function likely has deep evolutionary roots. As the human face became more open and readable, the ability to quickly and accurately recognize others’ faces took on new importance. Facial recognition became essential to social infrastructure. In a 2003 study, researchers wanted to uncover the role that eyebrows play and produced a result that still surprises people. Researchers took photographs of familiar faces and digitally altered them by removing either the eyes or the eyebrows in Adobe Photoshop. Participants were then asked to identify the faces. Intuition would lead you to believe that removing the eyes would be more disruptive. After all, eyes are often described as the most informative part of the face. But the results showed the opposite: removing the eyebrows caused a larger drop in recognition performance than removing the eyes.

The explanation lies in the kind of information different features provide. Eyes are rich in detail, in that they move, blink and shift direction. However, that same variability can also make them less reliable as stable identity markers. Eyebrows, on the other hand, offer more consistent, high-contrast shape information. Their thickness, curvature, spacing and symmetry become almost like a structural signature. You may have heard that the majority of communication occurs non-verbally through body language. This is why when you can ask your child, “How are you,” their “Fine,” may actually communicate the opposite based on tone, facial expression, and body posture. Eyebrows are a key player in facial expression. You can look at cartoon graphics of eyes and eyebrows, without any other features, and accurately determine emotions like anger, confusion, sleepiness, happiness or fear. The eyebrows’ angle, arch, and movement are important non-verbal communicators. Our human brains are naturally wired to read, assess and translate what eyes and eyebrows express without us having to think about it. And, while neural-divergent children and adults may not inherently understand, working with images of eye/eyebrow expressions helps them learn to read the feelings of those closest to them. Not only are eyebrows essential to human communication, but they also help us to recognize one another. A social study used manipulated photos by eliminating the eyes or the eyebrows, evaluating which features were the most recognizable. It turned out study participants could recognize an average of 60% of the individuals when the eyebrows were there (without eyes), but only 40% were recognizable when the eyebrows were gone, and only the eyes remained. That was not what they’d predicted, and it demonstrates how much eyebrows affect facial recognition between humans. 

Eyebrows allow us to:

Signal emotion quickly and precisely

Navigate social interactions with nuance

Recognize one another with surprising accuracy

There are even suggestions that eyebrows contribute to perceived attractiveness, supported by work on facial aesthetics and sexual dimorphism. Subtle differences in shape and thickness can significantly influence how faces are judged. This is further supported by the amount of effort some of us invest in them, often without fully articulating why. Across cultures, people shape, pluck, thread and enhance their eyebrows. Cosmetic procedures aim to refine their position and movement. These practices reflect an intuitive understanding that our eyebrows matter. In fact, they matter enough that when they disappear, the face feels wrong. Evolutionarily speaking, that’s a big clue, as features that carry little importance tend to fade into variability or disappear altogether. Yet eyebrows have done the opposite: they have become more defined, more mobile and more functionally integrated into how we communicate and perceive. They also play a key role in defining the geometry of the upper face. The distance between the eyes and the brows, the angle of the arch, the balance between left and right, all of these contribute to what researchers call configural processing: the brain’s ability to recognize faces based on spatial relationships between features. When you remove the eyebrows, that geometry completely collapses. The face becomes harder to “parse,” even though the eyes themselves remain. The findings suggest that your eyebrows are what anchor your face.

Like every feature of the human body (including the eyes and vision health), eyebrows come in a wide range of shapes, colors, and textures. There are a few things they have in common. For example, most eyebrows follow the natural shape of your brow bone, and eyebrow hairs are usually coarser than those on your arms or legs. And, while most are the same general hue as the hair on a person’s head, they may grow lighter with sun exposure or as a person ages, and the brows turn grey. However, genetics are the most responsible for whether you have two distinct eyebrows or a single connected brow (referred to as a “unibrow”), as well as your eyebrows’ thickness/thinness, color, fine/coarseness, or the individual hairs’ lengths. However, other factors affect your eyebrows and their function such as:

Consistent plucking/waxing of the eyebrows can permanently destroy hair follicles, which changes your brows’ shape and thickness).

Some people’s eyebrows get much thinner or seem to almost disappear as they age, while others (particularly men) grow thicker, bushier and longer.

Some autoimmune diseases, like alopecia, madarosis, or other health conditions, can reduce or eliminate eyebrows due to hair thinning or loss.

How you can (or can’t) move your eyebrows is also genetic. Some people can raise one eyebrow at a time, while others can’t do it no matter how hard they practice.

Any injury to the tissue on or around the brow line can cause permanent changes. This is common for people with scarring on or around their eyebrows or those with (or had) eyebrow piercings, depending on how the injuries affect the brows’ hair follicles.

Reasons for most people being right handed

More than 90% Of humans are Right-Handed in nature : Why?

Roughly 90% of humans are right-handed and this is one of the traits which separates us from most other primates who don’t really show any overall preference for left or right handedness. The answer stretches back millions of years and involves fossils, language and genetics we still can’t fully decode.  It’s believed that handedness played an important role in human evolution, with a recent study on the earliest evidence of right-handedness in the fossil record shedding light on when and why this trait arose. Interestingly, the clues were found not in our ancient hands, but in our ancient teeth. We have long known that the human brain is composed of two roughly similar halves. The left hemisphere controls language and motor abilities, whereas the right hemisphere is responsible for visual-spatial attention. Think of how many times a day you use your hands to perform mundane tasks, like picking up a pen, opening a jar or grabbing your phone from across the table. Somewhere in the half-second before you act, your brain makes a choice, and for roughly 90% of people reading this, it chooses the right hand. This bias is so consistent, so stubbornly universal across every culture and continent we’ve ever studied, that it demands an explanation.

The story of human handedness stretches back millions of years and weaves together evolutionary pressure, brain architecture, embryonic biology and a healthy dose of genetic complexity we haven’t fully untangled. It is less well known that brain lateralisation, or the dominance of some cognitive processes in one side of the brain, is a distinctive feature of humans, and one associated with improved cognitive ability. The technical term for preferring one hand over the other is manual lateralization, and it is not uniquely human. Many vertebrates, and even some invertebrates, show individual hand or limb preferences. What sets humans apart is a population-level bias. Across virtually every human society ever studied, roughly 90% of people are right-handed. In other species, individual preferences exist, but the population splits roughly 50/50. Evidently, something happened in our lineage, something significant enough to tip the whole species to one side. The fossil record offers our earliest glimpses of when this tipping began. The makers of Oldowan stone tools, the oldest known toolkit, dating back 2.6 million years, were predominantly right-handed. This is a remarkable finding because it means that before Homo sapiens existed, before Homo erectus had fully flourished, hominins were already showing the same bias we carry today.

Could handedness have played a role in brain lateralisation? Ancient stone tools made and used by our earliest ancestors reveal some clues. The evidence for Neanderthals is even more evocative: scratch marks on the front teeth of Neanderthal fossils, left by stone tools being used while an object was gripped in the mouth, consistently run left-to-right, exactly the angle produced by a right-handed individual. Such striations have been found even on the teeth of children aged six to eight years old, which tells us that handedness wasn’t a late-developing adult trait but something which emerged early in development, and likely had a strong biological basis. Tracking this deeper, a large-scale comparative study of primate brain evolution found that the neurological groundwork for human-style lateralization was being built across tens of millions of years. The researchers identified critical shifts in the fronto-cerebellar system which occurred around 30 million years ago in ape ancestors, and further reorganization in the Homo-Pan lineage around 10 million years ago. By the time our genus emerged, the brain had already been quietly restructuring itself for asymmetry.

The earliest stone tools date to 3.3 million years ago and were found in modern day Kenya, Africa. Early stone tool making would have required a high level of dexterity. We know from experiments that have replicated tool-making processes that the brain’s left hemisphere, which is responsible for planning and execution, is active during this process. If natural selection had strongly disfavored left-handedness, it would have been eliminated long ago, but it hasn’t been. Left-handers make up roughly 10% of every human population ever studied, and cave paintings and skeletal evidence confirm this proportion has remained stable for millennia. The most compelling evolutionary explanation is frequency-dependent selection: being left-handed confers an advantage in competitive face-to-face interactions (e.g., combat, wrestling, certain sports etc.) precisely because most opponents have trained against right-handers. The minority is maintained because it is rare enough to be surprising. Knowing that right-handedness is ancient and universal still leaves the harder question unanswered: Why right? Why not left? Why not an even split? Researchers have proposed different non-exclusive hypotheses, and the honest answer is that all of them probably carry some weight.

In humans, language is overwhelmingly housed in the left hemisphere of the brain, which controls the right side of the body. The emergence of speech and gesture as intertwined systems may have deepened the link between left-hemisphere dominance and right-hand preference. As language became central to human survival, the left hemisphere became the brain’s chief executive, and the right hand followed. 

This is probably the most intuitive hypothesis that Precision manipulation (e.g., knapping flint, shaping bone, hafting spear points, etc.) is asymmetric work. The dominant hand does the fine-grained work; the other hand stabilizes. Natural selection would have favored any individual whose neural wiring made that division of labor faster and more reliable, and over millions of years, the right hand won out. 

 We are a deeply imitative species. A parent demonstrating how to tie a knot or shape a pot is far easier to follow when learner and teacher share the same dominant hand. In a population already biased toward right-handedness, the social benefits of conforming to the majority would reinforce the bias across generations.

The idea that complex, sequentially organized behaviors (e.g., cooking a meal, building a shelter, performing a ritual, etc.) require a kind of neural project management. There’s reason to believe that the left hemisphere is better equipped for this kind of hierarchically structured planning, which would again drag skilled motor control toward the right hand.

None of these hypotheses is sufficient alone. Together, they sketch a portrait of handedness as the convergent product of biomechanics, neurolinguistics, cognitive architecture and social learning, a trait that was useful in many different ways simultaneously. Then there are the truly ambidextrous, and here, a crucial distinction is often blurred in popular writing. Mixed-handedness, or cross-dominance, means using different hands for different tasks. It is relatively common, affecting perhaps a quarter of the population, depending on how you measure. True ambidexterity, equal skill and speed with both hands across all tasks, is extraordinarily rare, estimated at around 0.1% of the population. Neuroimaging typically shows weaker hemispheric dominance, compensated by a thicker corpus callosum (the band of nerve fibers connecting the two hemispheres). When neither hemisphere fully claims motor leadership, the brain builds a wider communication channel between them. This reduced lateralization also extends to language, meaning ambidextrous individuals tend to be less strongly lateralized for speech as well. This is not, as popular mythology sometimes suggests, an uncomplicated advantage. Studies of mixed-handed children have found higher rates of language and academic difficulties, and elevated rates of attention-related problems by adolescence. Weak lateralization doesn’t cause these outcomes, but it still reflects that typical brain asymmetry is, in most cases, a feature rather than a bug. A lopsided brain is an efficient brain.

At the same time, humans are overwhelmingly right-handed when it comes to tool making compared to other species. This is most likely because the left and right hemispheres control motor action on the opposite sides of the body. While this relationship is not straightforward, it would appear that, in most cases, handedness and brain lateralisation go hand in hand (pun intended). So why use teeth to investigate handedness? The answer lies in the scarcity of matching left and right arm bones in the fossil record, particularly those belonging to our earliest ancestors. Without matching left and right sets, it is impossible to examine differences in size and shape to determine which hand an individual favoured when completing manual tasks. Teeth, on the other hand, tend to survive relatively well in the fossil record and can preserve scratches, or “striations”, which establish handedness. In an earlier study, researchers noted striations on the front side of teeth belonging to European Neanderthals. They hypothesised that these marks were made when material was held in one hand and gripped between the front teeth and worked by the other hand with a stone tool, with the stone tool occasionally striking these teeth. These actions were replicated during experiments in which participants wore mouthguards. The results indicated that right-slanting striations are made on teeth when material is pulled with the left hand and struck with the right hand. Right-slanting striations are therefore a good indicator of right handedness.

The subject of the new study, an ancient upper jawbone, provides the oldest evidence for right-handedness known in our genus Homo. The jawbone belonged to one of our earliest human ancestors, Homo habilis (literally, the “handy man”), who roamed Tanzania in Africa around 1.8 million years ago. The jaw was identified at Olduvai Gorge in the Serengeti Plain, which has yielded some of the earliest archaeological traces around us. Your dominant hand is the product of an evolutionary story. It’s written into your genome across dozens of loci, shaped by the hemisphere that also gives you language, and reinforced by every right-handed teacher who ever showed you something. It is, in the most literal sense, your most ancient inheritance. The study noted a number of striations on the front side of the teeth. They used high-powered microscopes and digital cameras to investigate these striations, particularly patterning in their direction. Interestingly, nearly half of all striations were right-slanting. Right-slanting striations were particularly dominant on four of the front teeth (left and right central incisors, right second incisor and right canine). This led to argue that most marks were made with the individual’s right hand. It also suggested that the four front teeth with many right-slanting striations were the focus of most processing activities. The Homo habilis jaw is important as it provides the oldest evidence for right-handedness in the fossil record. But it is also significant as it suggests that a major level of brain organisation had occurred in humans by at least 1.8 million years ago. This brain development enabled us to master crucial early skills such as stone tool making and potentially also paved the way for language development. Right-handedness therefore means a lot more to us than simply a preference for using the right hand.

Reasons for variable venom in snakes

 Some snakes have simpler venom instead of Potent one  

By comparing records of venom potency and quantity for over 100 venomous snake species, researchers have discovered that the potency of a snake's venom depends on what it eats. Contrary to long-held beliefs, new research reveals rattlesnakes are not solely developing more complex venoms. In isolated habitats with limited prey diversity, these snakes have evolved simplified venom compositions, focusing on highly effective toxins. This ecological efficiency, rather than a deficit, demonstrates the remarkable adaptability of rattlesnake venom to local environments. Scientists had long believed that venomous snakes had, over the years, been developing more and more complex venoms to ensure that they immobilized as many types of prey as possible. The more complex venom, therefore, was seen as the ultimate weapon. However, new research has shown that there was a twist to the evolution of the venom of the rattlesnake. The snakes are not only making it more complex but are also making it less complex.

Snakes are infamous for possessing potent venoms, a fact that makes them deadly predators and also strikes fear into humans and other animals alike. However, some species, such as cobras, boomslangs and rattlesnakes have far more venom than they apparently need, in a single reserve of venom, they have the potential to kill thousands of their prey animals and several adult humans. The Guardian also reported that the venom profile of these island rattlesnakes is a very close match to the prey species that are most dominant in their ecosystems. Despite the above simplification, the rattlesnake still has a vast genetic arsenal that enables it to vary the venom profile whenever the need arises. Studies conducted by the National Science Foundation have pointed out that the rattlesnake has a vast array of genes that code for the production of venom toxins. As prey animals gain resistance to various toxins, the snake adapts by changing the chemical makeup of its venom. But when the number of prey animals is limited, natural selection focuses on maximizing the potency of a smaller number of highly effective toxins, rather than the range of different ones.

But not all venomous snakes are so dangerous. For example, the marbled sea snake has only a tiny amount of very weak venom, making it effectively harmless to any relatively large animals such as humans. Why venoms vary so much in their ability to kill or incapacitate potential prey animals has long puzzled scientists, with several competing hypotheses suggested as explanations. Recent research has also shown that rattlesnakes have evolved optimized venom compositions that have fewer types of toxins, especially in remote habitats where there is limited diversity of prey. Rather than having a rich chemical arsenal, the snakes have focused on developing toxins that are most effective against the few species of prey that they encounter regularly. This is no longer considered an evolutionary deficit but rather a case of ecological efficiency. The study tackled this puzzle by comparing records of venom potency and quantity for over 100 venomous snake species, ranging from rattlesnakes, cobras and the tree dwelling boomslangs of Africa to sea snakes and burrowing asps. The team found strong evidence that venoms have evolved to be more potent against animals that are closely related to the species that the snake commonly eats. These results make sense from an evolutionary viewpoint as we expect that evolution will have shaped venoms to be more efficient at killing the prey animals they are most often the target of the venom. You won't find many mice in the sea so we wouldn't expect a sea snake to evolve venom that is more effective at killing mice than fish. Evidence for this phenomenon is particularly evident in populations of rattlesnakes that live on remote islands. According to an earlier study done by researchers at the University of South Florida, populations of rattlesnakes that live on uninhabited islands in the Gulf of California have venoms that contain significantly fewer families of toxins than those living on the mainland. This is due to a lack of prey diversity.

The research also showed that the amount of venom a snake has depends on both its size and the environment it lives in. Like all substances venom is dosage-dependent. Even alcohol, coffee and water can be toxic at high enough volumes so we needed to consider how much venom different species of snake produce and store in their venom glands. We found that big terrestrial species have the most venom, while smaller tree dwelling or aquatic species had the least. This difference may be due to how often a snake encounters its prey in these different environments, with terrestrial species requiring a larger reserve of venom to take advantage of the rarer opportunities to feed. Another fascinating find is that the reduced venom profiles are found in various lineages of snakes who have evolved independently. A study conducted in 2021 revealed that the proteins in snake venom have evolved convergently, implying that various species of snakes can have similar venom profiles despite being distantly related. Did you have any idea that the interaction between venom and prey resistance is another factor which greatly influences the composition of venoms? Yes, the interaction between rattlesnakes and California ground squirrels was investigated. Evidence of coadaptation between the predator and the prey was established.

Together, these studies show that the flexibility of rattlesnake venom is far greater than anyone ever imagined. In fact, it turns out that the venom has adapted to the local environment, not to the level of complexity. In some environments, the best venom is the one that is least complex. The results of the study also have potential to aid in our understanding when it comes to human snakebites. Snakebites are a major health concern worldwide, with 2.7 million cases each year. Understanding how venom evolves may help us better identify the risks to humans from different snake groups, and also potentially from other venomous animals such as spiders, scorpions, centipedes and jellyfish. The approach used in the study may also help researchers predict the potency of venoms in species that have yet to be tested, and even pinpoint potentially useful healthcare-related applications. The next step is to see how well this model may predict the potency of venoms in groups that have yet to have their venoms tested. By using ecological and evolutionary data for available species we may be able to use our approach as a tool to identify other species which may have properties in their venoms which are useful for biomedical purposes around the world.