Stroke risk highest among Native Hawaiian, Pacific Islander people

American Academy of Neurology

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MINNEAPOLIS — A new study found that Native Hawaiian or Pacific Islander people had the highest rate of stroke among people from other race and ethnic groups, with a rate more than three times higher than that of white people. The study is published on August 27, 2025, in Neurology®, the medical journal of the American Academy of Neurology.

“Multiple studies have shown racial and ethnic disparities in the rate of stroke in the United States, but there is little information on the rate among Native Hawaiian or Pacific Islander people, especially among those living in the contiguous US mainland,” said study author Fadar O. Otite, MD, MS, of the State University of New York Upstate Medical University in Syracuse and a member of the American Academy of Neurology. “Since Native Hawaiian or Pacific Islander people are among the fastest growing populations in the US and have one of the highest rates of death from cardiovascular disease, we wanted to focus on the risk among this group.”

Researchers examined databases from Florida, Georgia, Maryland and New York for cases of ischemic stroke during a period of up to six years. Ischemic stroke, the most common type of stroke, is when blood flow is blocked to part of the brain.

The stroke cases were combined with Census data from each state on the number of white, Black, Hispanic, Asian, and Native Hawaiian or Pacific Islander people to determine the rate of stroke.

There were 799,150 cases of stroke during the study. After adjusting for age and sex, researchers found the stroke rate for Native Hawaiian or Pacific Islander people was 591 cases for 100,000 people, compared to 292 cases for Black people, 180 cases for white people, 145 cases for Hispanic people and 108 cases for Asian people.

After researchers adjusted further for year of hospitalization to account for advances in stroke care, they found that the stroke rate was 3.3 times higher among Native Hawaiian or Pacific Islander people than among white people, almost four times higher than among Hispanic people and more than five times higher than among Asian people. Native Hawaiian or Pacific Islander people had a lower rate of stroke than Black people in Florida, but a higher rate in Georgia, Maryland and New York.   

“More research is needed into the reasons for this disparity so that it can be tackled appropriately,” Otite said. “These findings also lend support to the need for parsing out information on race and ethnicity in health care databases, where Asian people and Native Hawaiian or Pacific Islander people are usually combined into one large group.”

A limitation of the study was that only strokes where the person was taken to the hospital were captured, so the total number of cases would be higher if people who never went to the hospital were included.

Discover more about stroke at BrainandLife.org, from the American Academy of Neurology. This resource also offers a magazine, podcast, and books that connect patients, caregivers and anyone interested in brain health with the most trusted information, straight from the world’s leading experts in brain health. Follow Brain & Life® on Facebook, X, and Instagram.

The American Academy of Neurology is the leading voice in brain health. As the world’s largest association of neurologists and neuroscience professionals with more than 40,000 members, the AAN provides access to the latest news, science and research affecting neurology for patients, caregivers, physicians and professionals alike. The AAN’s mission is to enhance member career fulfillment and promote brain health for all. A neurologist is a doctor who specializes in the diagnosis, care and treatment of brain, spinal cord and nervous system diseases such as Alzheimer's disease, stroke, concussion, epilepsy, Parkinson's disease, multiple sclerosis, headache and migraine.

Explore the latest in neurological disease and brain health, from the minds at the AAN at AAN.com or find us on Facebook, X, Instagram, LinkedIn, and YouTube.

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Journal

Neurology

 

Ancient DNA reveals farming spread through migration, locals slow to adopt it

Penn State

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Matthew Williams, academic affiliate assistant professor of biology at Penn State (left), and Christian Huber, assistant professor of biology at Penn State, are part of a team that used sophisticated computer simulations, ancient DNA, and archaeological evidence to measure the forces that drove farming’s expansion.  

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Credit: Michelle Bixby / Penn State

UNIVERSITY PARK, Pa. — Roughly 10,000 years ago, humans started shifting from being nomadic hunter-gatherers to building large agricultural settlements, marking one of the greatest transformations in human history. This transition, known as the Neolithic Revolution, began in the Fertile Crescent of the Middle East and led to the spread of farming throughout Europe. For decades, researchers have debated what drove this change. Did farming spread mainly because farmers themselves moved into new lands, or because hunter-gatherers adopted farming practices?

New interdisciplinary research by scientists at Penn State provides the clearest answer to date. Using mathematical models, computer simulations, and ancient DNA analysis, the team was able to measure how migration and cultural adoption each contributed to the expansion of farming. Their findings, published this week (Aug. 25) in Nature Communications, show that migration of farming groups was the dominant factor, while cultural adoption by hunter-gatherers only played a minimal role.

“Archaeology and genetics offer complementary windows onto this transition,” explained Christian Huber, assistant professor of biology at Penn State and senior author on the paper. “For example, artifacts and isotopes in ancient bones can reveal whether a person relied on domesticated plants or animals, reflecting the adoption of new farming practices. At the same time, DNA preserved in those bones can show where people’s ancestors came from, providing evidence of migration, or the movement of farming populations into new regions.”

Using sophisticated computer simulations, ancient DNA and archaeological evidence, Huber’s team was able to measure the forces that drove farming’s expansion — and how influential each force was.

“This has been a long-standing question — and disentangling the roles of migration and cultural adoption has been a goal of archaeologists and anthropologists for decades,” said Troy LaPolice, doctoral student at Penn State and lead author of the study. “What we found was surprising: when cultures spread through migration, it is not guaranteed local ancestry patterns will change, but the spread of farming managed to leave a strong and lasting impact on European ancestry.”

By building models that simulate population movement, growth and cultural learning, and fitting them to the known rate of farming expansion and ancestry data from 618 European Neolithic individuals derived from ancient DNA, the team was able to quantify the contributions of both migration and cultural adoption.

“It's really interesting to be able to understand a time period before any written or oral history,” LaPolice said. “This intense interdisciplinary project allowed us to undertake a new kind of historical reconstruction.”

The team found that the adoption of new ideas and practices did not significantly accelerate the spread of agriculture. Hunter-gatherers appear to have largely continued to forage even as farming expanded and gradually displaced their way of life. The contribution of cultural transmission to farming’s spread, known as the “cultural effect,” was minimal, estimated at only about 0.5%.

“The assimilation rate, the rate at which hunter-gatherers were grafted into farming communities, was actually very low — only about one in 1,000 farmers converted a hunter-gatherer to farming each year,” Huber said. “As a result, cultural transmission had almost no effect on how quickly farming spread. Still, even at this low rate, it left a lasting mark on the DNA of Europeans today and introduced useful genetic traits into the growing farming communities.”

The researchers also found that mating was largely restricted to within cultural groups, meaning farmers predominantly mated with other farmers and hunter-gatherers with other hunter-gatherers. Any “between-group mating” was remarkably rare, estimated at less than 3%, according to their models. This aligns with evidence from other ancient DNA studies showing minimal gene flow even where foragers and farmers co-existed for centuries, explained Matthew Williams, academic affiliate assistant professor of biology and co-author on the paper.

Williams and Huber have also published two recent papers where they tested commonly used methods for studying ancestry in ancient people. Their work shows how these tools can shed light on human movement through history, but also points out where they can be misleading if used without care. One paper was published in Genome Biology and the other in Genetics.

“This research highlights the power of combining genetic data with archaeological models to uncover the complex behavioral mechanisms of our past,” Williams said. “Looking forward, I see this paving the way for a re-evaluation of other major prehistoric cultural shifts.”

The U.S. National Institutes of Health funded the research.

At Penn State, researchers are solving real problems that impact the health, safety and quality of life of people across the commonwealth, the nation and around the world. 

For decades, federal support for research has fueled innovation that makes our country safer, our industries more competitive and our economy stronger. Recent federal funding cuts threaten this progress. 

Learn more about the implications of federal funding cuts to our future at Research or Regress.  

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Journal

Nature Communications

DOI

10.1038/s41467-025-63172-0 

Method of Research

Computational simulation/modeling

Subject of Research

People

Article Title

Modeling the European Neolithic expansion suggests predominant within-group mating and limited cultural transmission

Article Publication Date

25-Aug-2025

 

Researchers turn mouse scalp transparent to image brain development

Stanford University

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Left: 3D reconstruction of two-photon excited YFP-H fluorescence in the live mouse cortex before treatment with ampyrone. Only YFP signals in the scalp can be seen due to the scattering of the scalp. Right: 3D reconstruction of two-photon excited YFP-H fluorescence of the same region after achieving scalp transparency with ampyrone. | The Hong Lab

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Credit: The Hong Lab

During childhood and adolescence, our brain goes through a lot of changes. But studying those changes in juvenile mice is challenging because scientists don’t have a way to repeatedly image the same animal’s neural pathways as they grow.

Now, by simply rubbing a solution into a juvenile mouse’s scalp, researchers at Stanford can make the skin transparent to all visible light, allowing them to image the developing connections in a living mouse’s brain. And because the technique is reversible and non-invasive, the researchers can return to the same animal over days and weeks. The work, published Aug. 26 in PNAS, creates new opportunities for research on the developing brain that could improve our understanding of neurodevelopmental disorders and lead to new interventions.

“This opens a literal window to peek into the brain’s development,” said Guosong Hong, an assistant professor of materials science and engineering and senior author on the paper. “Not only can we image the structures of these neurons, but we can also image the neural activity over time in an animal model. In the future, this approach could enable us to look at how these circuits form during the development of an animal.”

Harnessing fundamental laws for new discoveries

Normally, light scatters when it hits skin. Light scattering occurs whenever light waves encounter interfaces between materials with different optical properties. So, under the skin, it also scatters as it encounters lipids, proteins, and molecules inside tissue. Like trying to see through sunlit fog, light scattering causes similar challenges when they attempt to peek inside or through tissues.

“From a physics perspective, we’re basically a bag of water with biomaterials,” said Mark Brongersma, the Stephen Harris Professor and professor of materials science and engineering and co-author on the paper. “And the mismatch in their optical properties is why we can’t see through the skin or scalp.”

The key to making skin transparent is by making the water and biomaterials more similar in their optical properties. This can be accomplished by raising the refractive index of the water – how much it bends light – to match the refractive index of the rest of the biomaterials in the body. The researchers found that by mixing a compound called ampyrone into water and rubbing it on the skin of a mouse, they could raise the refractive index of the water in the mouse’s skin, turning it transparent. And because ampyrone almost exclusively absorbs ultraviolet light, the inside of the mouse can be seen with the whole visible spectrum.

“The fact that such fundamental optics laws can be applied and work in a biological system is just amazing to me,” Brongersma said. “It wasn’t clear whether the physics and the chemistry and the biology would all line up to make this happen.”

The work builds on the team’s groundbreaking discovery of a compound that turns skin transparent to red light, allowing them to view a mouse’s internal organs without making an incision. Now, because ampyrone permits the whole visible spectrum of light, the team can see the colors of green and yellow fluorescent proteins that are commonly used to mark neural activity. Young mice have very thin skulls, so this fluorescence can be seen until the mouse is about four weeks old (the equivalent of a human teenager or early adult). The researchers were able to repeatedly image the neurons of sedated juvenile mice and see how neural activity changed in awake mice responding to a puff of air on their whiskers.

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Journal

Proceedings of the National Academy of Sciences

DOI

10.1073/pnas.2504264122 

Article Title

Color-neutral and reversible tissue transparency enables longitudinal deep-tissue imaging in live mice

Article Publication Date

26-Aug-2025

Wheat that makes its own fertilizer

Bacterial work-around aims to reduce pollution, lower costs for farmers

University of California - Davis

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Scientists at the University of California, Davis, have developed wheat plants that stimulate the production of their own fertilizer, opening the path toward less air and water pollution worldwide and lower costs for farmers.

The technology was pioneered by a team led by Eduardo Blumwald, a distinguished professor in the Department of Plant Sciences. The team used the gene-editing tool CRIPSR to get wheat plants to produce more of one of their own naturally occurring chemicals. When the plant releases the excess chemical into the soil, the chemical helps certain bacteria in the soil convert nitrogen from the air into a form the nearby plants can use to grow. That conversion process is called nitrogen fixation.

The study was published online in Plant Biotechnology Journal. 

In developing countries, the breakthrough could be a boon for food security.

“In Africa, people don't use fertilizers because they don’t have money, and farms are small, not larger than six to eight acres,” Blumwald said. “Imagine, you are planting crops that stimulate bacteria in the soil to create the fertilizer that the crops need, naturally. Wow! That’s a big difference!”

The breakthrough in wheat builds on the team’s earlier work in rice. Research also is underway to extend this technology to other cereals. 

Worldwide, wheat is the No. 2 cereal crop by yield and takes the biggest share of nitrogen fertilizer, using about 18% of the total. Globally, more than 800 million tons of fertilizer were produced in 2020 alone, according to figures from the United Nations Food and Agriculture Organization.

But plants take up only about 30 to 50% of the nitrogen in fertilizer. Much of what they don’t use flows into waterways, which can create “dead zones” that lack oxygen, suffocating fish and other aquatic life. Some excess nitrogen in the soil produces nitrous oxide, a potent climate-warming gas. 

The work-around: Protect the fixer

Nitrogen-fixing bacteria produce an enzyme called nitrogenase, the “fixer” in nitrogen fixation. Nitrogenase is only located in the bacteria, and it can only work in environments with very little oxygen. 

Legumes such as beans and peas have root structures, called nodules, that provide a cozy, low-oxygen home for nitrogen-fixing bacteria to live. 

Unlike legumes, wheat and most other plants don’t have root nodules. This is why farmers use nitrogen-containing fertilizer.

“For decades, scientists have been trying to develop cereal crops that produce active root nodules, or trying to colonize cereals with nitrogen-fixing bacteria, without much success. We used a different approach,” Blumwald said. “We said the location of the nitrogen-fixing bacteria is not important, so long as the fixed nitrogen can reach the plant, and the plant can use it.”

To find a work-around, the team first looked at 2,800 chemicals the plants produce naturally. They found 20 that, among other jobs useful to the plant, also stimulate bacteria to produce biofilms. Biofilms are a sticky layer that surround the bacteria and create a low-oxygen environment, allowing nitrogenase to work. The scientists determined how the plant makes those chemicals and which genes control that process. 

Then, the team used the gene-editing tool CRISPR to modify wheat plants to produce more of one of those chemicals, a flavone called apigenin. The wheat, now with more apigenin than it needs, releases the excess through its roots into the soil. In experiments they conducted, apigenin from the wheat stimulated bacteria in the soil to create the protective biofilms, allowing nitrogenase to fix nitrogen and the wheat plants to assimilate it.

The wheat also showed a higher yield than control plants when grown in a very low concentration of nitrogen fertilizer.

Farmers could save billions

Farmers in the United States spent nearly $36 billion on fertilizers in 2023, according to U.S. Department of Agriculture estimates. Blumwald calculates that nearly 500 million acres in the U.S. are planted with cereals.

“Imagine, if you could save 10% of the amount of fertilizer being used on that land,” he pondered. “I’m calculating conservatively: That should be a savings of more than a billion dollars every year.”

Other authors include Hiromi Tajima, Akhilesh Yadav, Javier Hidalgo Castellanos, Dawei Yan, Benjamin P. Brookbank and Eiji Nambara. 

A patent application has been filed by the University of California and is pending. Bayer Crop Science and the UC Davis Will Lester Endowment have supported the research.

Read about the earlier work of the Blumwald team to develop rice that can stimulate its own nitrogen fertilizer here.

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Journal

Plant Biotechnology

DOI

10.1111/pbi.70289 

Method of Research

Experimental study

Subject of Research

Cells

Article Title

Increased Apigenin in DNA-Edited Hexaploid Wheat Promoted Soil Bacterial Nitrogen Fixation and Improved Grain Yield Under Limiting Nitrogen Fertiliser

Article Publication Date

6-Aug-2025

COI State

 

Certain communities of pond plants may increase greenhouse gases

Cornell University

ITHACA, N.Y. - The composition of aquatic plant communities in shallow freshwater bodies, including floating plants, submerged plants and phytoplankton, can have important effects on greenhouse gas production, transport and emissions, according to a new study by Cornell University researchers.

 

The findings could lead to aquatic plant management strategies that help mitigate the release of gases such as methane (CH4), carbon dioxide (CO2) and nitrous oxide (N2O). About half of all the CH4 emissions on the planet originate from aquatic sources, with wetlands, ponds and shallow lakes accounting for most of it. CH4 is a powerful greenhouse gas that is roughly 28 times more potent over 100 years than CO2.

 

Meredith Theus, a doctoral student and the lead author of the study, set up a summer field experiment from late spring to early fall at the Cornell Experimental Ponds Facility. Within each of three ponds, she set up three corrals (mesocosms) to establish the following three treatments: submerged plants (whose roots are in sediment); submerged and floating plants (such as duckweed that float freely on the surface); and phytoplankton (tiny plants like algae that float in the water column). She then collected water column chemistry measurements, including dissolved greenhouse gas concentrations, every two weeks. She sampled greenhouse gas fluxes (gases emitting from the water into the atmosphere) for methane, carbon dioxide and nitrous oxide using a portable greenhouse gas analyzer.

 

The experiments revealed that the treatment with submerged plants and floating plants had the highest water column concentrations of CO2 and CH4, and the lowest N2O concentrations, but those results weren’t reflected in the fluxes, which showed no differences between the three treatments.

 

“You’d think surface water concentrations would be similar to fluxes because if you had more of something in the water, you’d have more of that thing coming out, but we didn’t see that,” said co-author Meredith Holgerson, associate professor in the Department of Ecology and Evolutionary Biology.

 

One reason for this result, she said, could be that floating plants like duckweed, while individually small, can collectively blanket the water and block gases from escaping into the atmosphere.

 

“Some of our previous research has found the highest concentrations of CH4 in ponds that are completely covered with duckweed, because the duckweed acts like a lid,” Holgerson said.

 

One caveat: Data wasn’t collected every day, so flux measurements may not have captured gases escaping when a big wind pushed duckweed to one side of the pond.

 

Also, the system is complicated, as tiny duckweed roots have been shown to house bacteria called methanotrophs, which consume CH4 and break it down. The study takes an important step toward informing future research that might explain the discrepancies between greenhouse gas concentrations and fluxes.

 

For additional information, read this Cornell Chronicle story.

 

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Journal

Aquatic Botany

 

Genetic key to why immune responses differ between men and women

University of York

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A new study has uncovered a key difference between the immune system of males and females - and it comes down to a single gene.

It is known that biological sex affects the function of the immune system, with women often being more severely affected by autoimmune conditions or allergic diseases.

Scientists from the University of York have now identified the gene Malat1 as a critical player in regulating immune responses in female immune cells, but not in males. 

The team studied T cells, a pillar of our immune system, in the lab and animal models of inflammation. The study focused on a type of immune cells called Th2 cells, which protect the body from parasitic infections, such as schistosomiasis, but also promote severe allergies, such as severe asthma. 

Professor Dimitris Lagos, from the University of York and Hull York Medical School, said: “Malat1 appears to be part of the bigger picture of what makes female T cells different. It is a gene that produces an RNA but not a protein. It is fascinating that even though it is present in both female and male T cells, it seems to be working differently in female cells.”

Over 240 million people are affected by asthma worldwide, a quarter of whom exhibit severe disease, with over 60% of severe adult patients being female. Similarly, over 200 million people are affected by schistosomiasis, a disease caused by helminth parasites, with over 100 million adolescent girls and 138 million pregnant women living in endemic areas.

The team discovered that, in female mice, Th2 cells did not develop appropriately during lung inflammation when the gene Malat1 was missing. However, this defect was not seen in male mice.

Professor Lagos said: “We see a drop in immune cell function in females when this gene is absent. Its loss disrupts how immune cells develop - particularly their ability to produce important molecules involved in inflammatory responses called cytokines.

“This contributes to a rapidly developing body of knowledge that tries to explain why men and women sometimes respond differently to the same infection, allergen, inflammation trigger, or immune therapy. It demonstrates that a one-size-fits-all treatment approach may not always be effective.”

“Understanding the biology of female immune cells could lead to more effective treatments, tailored to biological sex, for diseases of the immune system, including infections affecting millions of people in some of the poorest communities in the world and common conditions such as severe asthma.”

The next stage of the work is to examine these results in human immune cells and explore how Malat1 works to fine-tune immune responses, leading to development of more effective treatments.

The study is published in The Journal of Immunology.

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Journal

Immunology