Health

Overpopulation can impair fertility. New study explains why

Lisa Marshall — Thu, 21 May 2026 12:18:27 +0000

Overpopulation can impair fertility. New study explains why Lisa Marshall Thu, 05/21/2026 - 06:18

Lisa Marshall

Scientists have reported it for decades: Overpopulation can impair reproduction.

Crowded chickens lay fewer eggs. Crowded mice have smaller broods. In humans, several studies have associated increased population density with reduced fertility.

External factors, such as resource scarcity and social influences, undoubtedly play a role. But researchers have long suspected that intrinsic, biological mechanisms may also be at play as an evolutionary tool to keep populations in check.

New �鶹��Ѱ��Boulder research, published this month in the journal Nature Communications, identifies one key mechanism.

It found that overcrowded animals secrete a chemical messenger that can damage eggs, impair embryos and cause genetic mutations in offspring for generations to come.

“It has been well documented that population density has a direct and negative impact on human and animal fertility, but the underlying mechanisms have been elusive,” said senior author Ding Xue, professor of molecular, cellular and developmental biology at �鶹��Ѱ��Boulder. “Our study provides novel insights into how overpopulation can cause various developmental defects, including reduced fertility and increased mortality.”

The study comes as the world population nears 8.3 billion—three times what it was in 1950. Meanwhile, the authors note, birth rates are on the decline. Worldwide, the fertility rate has gone from five births per woman in 1950 to 2.3 births in 2021. According to the World Health Organization, one in six people experience infertility (defined as the inability to achieve a pregnancy after 12 months of trying).

“Overpopulation and crowding stress have emerged as major challenges in contemporary societies, especially in urban cities, where two-thirds of the world population live,” said Xue. “Our study may provide important molecular insights into the underlying health problems that can come with it.”

What radiation and overcrowding have in common

Xue’s team stumbled upon the findings serendipitously while studying a phenomenon known as radiation induced bystander effect (RIBE).

RIBE occurs in cancer patients receiving radiation therapy, when untreated, healthy cells outside a radiated site are also affected and damaged, leading to side effects like hair loss, fatigue and reproductive issues. Due in part to concerns about RIBE, pregnant women are advised to avoid radiation exposure.

In a 2017 study, published in Nature, Xue discovered what drives this bystander effect in the C. elegans worm: Cells stressed by radiation release a protein called cysteine protease related 4 (CPR-4), which travels to other healthy cells around the body and damages their DNA.

Other species across the animal kingdom, including humans and mice, have a similar chemical messenger called Cathepsin B cysteine protease.

Years later, in a follow-up study, Xue’s team noticed that, even in the absence of radiation, if worms lived in extremely crowded conditions, they emitted the protein.

At the molecular level, Xue said, the crowded animals looked a lot like they had been exposed to radiation.

Mutations passed through generations

For the new study, the team compared worms living in various-sized colonies. They found the worms typically didn’t secrete CPR-4, but once their colony exceeded 3,000 individuals, they did. The more overcrowded they were, the more of the enzyme they secreted, and the enzyme damaged their DNA. Experiments in mice showed similar results.

On average, those living in crowded conditions had 87% more genetic mutations in germ cells (reproductive cells). The animals had significantly fewer offspring. Also, the surviving offspring often had visible defects.

Genome sequencing showed some of those genetic mutations were passed on through generations, suggesting that overcrowding may drive genome evolution.

When the researchers silenced the protein in animals, it prevented the adverse effects of crowding. This suggests the enzyme plays a critical role in reproductive problems.

More research is necessary to determine whether the findings have implications for humans and other animals.

Xue has already developed and patented a compound that can inhibit the Cathepsin B cysteine protease enzyme in animals and has a good safety profile.

He believes such inhibitors could someday be used in agriculture, for example, to increase egg or fish production. The findings could also inform new approaches to helping humans struggling to have a family.

Overcrowded animals produce an enzyme that damages DNA in eggs, potentially sabotaging reproduction, new research shows. The findings could inform new approaches for improving fertility in people and animals.

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A crowd of thousands crowds into a Muse concert in Paris. Photo: Creative Commons

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Thousands crowd into a Muse concert in Paris. Credit: Creative Commons

Diseases can spread between apartments via shared ventilation, study shows

Lisa Marshall — Tue, 12 May 2026 23:58:11 +0000

Diseases can spread between apartments via shared ventilation, study shows Lisa Marshall Tue, 05/12/2026 - 17:58

Lisa Marshall

In June 2020 COVID-19 swept through this seven-story building in Santander, Spain. A new study shows the virus spread through the ventilation system. Photo credits: David Higuera. Video courtesy: El Pais Newspaper.

Airborne diseases like measles, influenza and COVID-19 can easily spread between units in multifamily buildings via a type of bathroom ventilation system commonly used around the world, new research suggests.

The study, conducted inside an older high-rise in Spain early in the coronavirus pandemic, adds to a growing body of evidence that airborne viruses can spread between separated indoor spaces, transmitting disease without face-to-face contact.

“We tend to think that if we shut the door in our apartment, we are safe and can’t get infected. But our study shows that, depending on the ventilation system in place, that may not be the case,” said senior author Shelly Miller, professor emerita in the Department of Mechanical Engineering at �鶹��Ѱ��Boulder.

Published in the journal PLOS One on May 12, the research was a collaboration between �鶹��Ѱ��Boulder, the University of Valencia and the University of Cantabria in Spain, and Concordia University in Canada.

‘The ghost in the room’

The project got its start in Santander, Spain, in June of 2020, just as residents began to emerge from lockdown. Cases had dropped to zero, and people were still masking and social distancing, when residents of a seven-story building got a call from public health officials: Someone on the third floor had tested positive for the SARS CoV2-virus.

The building was locked down again. But soon 15 people across four vertically stacked apartments had contracted COVID-19.

Engineer David Higuera lived in the building with his wife and two small children. They had a hunch that the ventilation shafts connecting bathrooms were to blame.

“I knew that, if what my wife and I suspected was happening, it could have significant scientific implications for public health,” said Higuera, a co-author on the study.

Higuera contacted regional health authorities and the press, but he said he was initially met with “very little interest.”

So he partnered with Miller, a world expert in airborne particles, who was on sabbatical in Spain.

They worked with epidemiologists to genetically sequence samples from infected residents, confirming they likely got it from one another. Then they brought in specialized equipment, shipped from �鶹��Ѱ��Boulder, to measure airflow and air pressure in the building.

At one point, Higuera placed a plastic bag over the bathroom duct and filmed as it filled with air coming in from other units. In another experiment, the team remotely measured carbon dioxide levels throughout the day in a vacant apartment.

Carbon dioxide is emitted through human breath and wouldn’t be expected to exist at high levels in a vacant space. Yet the apartment was filled with it.

“It was like there was a ghost in the room,” said Higuera.

Team engineers developed a computer simulation to model how virus-laden particles, emitted from breath or flushed toilets, could flow throughout the building under different circumstances.

Ventilation ducts in the bathroom of the Santander building. Courtesy David Higuera.

As with many older buildings across Spain and around the world, the bathrooms weren’t designed to have windows or fans. Instead, they use the “stack effect” in which shared vertical ventilation shafts move air out through vents in the wall, exhausting it through the roof via natural convection.

The study found that shifts in weather could impact air pressure in the shaft, with hotter temperatures pushing air flow back through the vents. Switching on the kitchen exhaust hood could exacerbate the spread, sucking almost all the air from an adjacent bathroom into a nearby apartment within minutes.

“The most plausible transmission route for this outbreak was the bathroom vertical ventilation duct system,” the authors conclude.

Could it happen elsewhere?

The study is not the first to document disease spreading through ventilation systems.

In 2003, during an outbreak of severe acute respiratory syndrome (SARS) in a Hong Kong high-rise, virus-laden particles made their way into a shared ventilation system via a bathroom floor drain, infecting 321 and killing 42 people.

The Santander building was built in 1969, and that type of ventilation system was phased out in Spain in 1975 with new building codes. But roughly one-third of the country’s buildings were built before then.

This type of ventilation is uncommon in the United States today, but similar systems still exist worldwide in older buildings.

“While this is a special building design more common in Spain, it illustrates a broader concern—that even if you are far from the source, if your air is connected, you can still get sick,” said Miller. “This can happen in a multifamily apartment building through the ducts, in a hotel between the hallway and rooms off the hallway, in office buildings between offices or on a cruise ship.”

Notably, Higuera installed a fan in his own bathroom during the pandemic, with a flap that prevented airflow from coming in. No one in his family got sick.

The authors are now calling on officials in Spain to update building standards to assure that older buildings take similar steps to mitigate disease transmission risk. They say architects everywhere should do more to address indoor air quality when designing new buildings.

For individuals wanting to reduce airborne contaminants in their own work or living space, Miller recommends using a high-quality air purifier.

Alberto Garcia, a recent mechanical engineering doctoral graduate from �鶹��Ѱ��Boulder, contributed to this study.

A detailed analysis of airflow in a high-rise building found a COVID-19 outbreak likely spread via the bathroom ventilation system. The findings have implications for other airborne diseases and for older multifamily buildings around the world.

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Why older adults are turning to weed

Lisa Marshall — Thu, 07 May 2026 16:09:49 +0000

Why older adults are turning to weed Lisa Marshall Thu, 05/07/2026 - 10:09

Lisa Marshall

Older adults are increasingly turning to cannabis to avoid taking pharmaceuticals, or as a “last resort” for pain, sleep, mental health issues and other age-related problems. But they have real concerns about the drug’s potentially intoxicating effects, according to new �鶹��Ѱ��Boulder and University of Utah research.

The study was published May 1 in the journal JAMA Network Open.

“For the most part, we found that these folks aren’t really interested in getting high. They just want to feel better,” said senior author Angela Bryan, professor of psychology and neuroscience at �鶹��Ѱ��Boulder.

Adults age 60 and older constitute the fastest growing demographic of cannabis users in the U.S. Yet previous research shows they often have trouble getting evidence-based advice from their doctors. The authors hope their findings, and more to come later this year from their first-of-a-kind study of older cannabis users, can inform new tools to help people navigate their decisions.

“Older adults would love to be able to talk about this with their primary care providers, but, unfortunately, the typical response they get is either, ‘I don’t know anything about it’ or ‘I can’t make any recommendations,’” said Bryan. “These patients often end up going to a dispensary and talking to a well-meaning 22-year-old budtender who doesn’t have the training to advise a 75-year-old with knee problems.”

The graying weed consumer

Between 2006 and 2013, the prevalence of people over age 65 who used cannabis soared 250% as legalization swept the country. Prevalence has continued to climb since, with 19% of adults ages 50–64 and 6% over 65 now using cannabis.

To understand why, and to explore the unique risks and benefits this group faces, the research team recruited 169 Colorado adults (average age 71) who were not regular cannabis users yet but were interested in trying edibles.

The researchers interviewed each participant at length.

Later, using �鶹��Ѱ��Boulder’s mobile laboratory, aka Cannavan, the team visited the homes of participants after they had used cannabis and invited them into the van for tests of balance, heart rate, cognition and other measures. (Because cannabis remains illegal at the federal level, such tests cannot take place in a lab on campus.)

Professional research assistants Paige Xiaoying Phillips (left) and Gray MacDonald pose for a photo inside the mobile pharmacology lab, aka the Cannavan, at �鶹��Ѱ��Boulder.

They found that 57% of older adults sought help for sleep, 50% for pain and 25% for mental health issues. Most were interested in a combination product including THC and CBD. Less than 14% sought THC-dominant products.

Many expressed concern that THC (the main psychoactive ingredient in marijuana) would impair their cognition or motivation (CBD—cannabidiol—does not generally cause intoxication).

“Combination products were perceived to be a ‘Goldilocks’ option,” the authors report.

Some limited evidence suggests that adding CBD to THC can augment a product’s anti-inflammatory properties while reducing some of THC’s intoxicating effects and paranoia, but more research is necessary to know for sure, said Bryan.

Participants often found their way to cannabis after exhausting other options, due to concerns about medication side effects, or because they thought they were already taking too many pills. In the absence of guidance from healthcare providers, they relied on advertising or word-of-mouth claims.

�鶹��Ѱ��Boulder Professor Angela Bryan

“We would love to see more conversations happening about this in the healthcare system, where physicians can help guide things,” said first author Rebecca Delaney, an assistant professor of population health sciences at University of Utah Health whose team develops “decision aids” (like pamphlets, videos and interactive websites) to help patients navigate healthcare decisions.

Bryan envisions a day when an older person considering cannabis could plug their ailment, age, other medications they’re on and preferences into a web-based decision aid and get science-backed advice on whether cannabis might help and which kind (CBD, THC or a combination? Edible or flower?).

Since little research has been done on older cannabis users, that advice is hard to come by now.

“At the end of the day, we want to help people make informed decisions,” Bryan said.

Custom cannabis for the older set?

Bryan notes that cannabinoid receptors in the brain and body dwindle with age—which may impact dosing. Some preliminary research suggests older adults may also be more sensitive to certain side effects, such as stomach problems from edibles.

Those with other age-related health problems may need to be more mindful of the impaired balance, elevated heart rate and acute cognitive problems that, according to the team’s preliminary findings, can come with higher levels of THC.

“The worst thing that can happen to an older adult is falling and breaking a hip, so that’s something some people need to consider,” said Bryan.

Forthcoming papers from the study will report how well cannabis worked and its acute and longer-term impacts. For now, Bryan says their work provides valuable insight to the cannabis industry: Tailoring some products to the over-60 set could be a wise idea.

“I think the takeaway for industry would be that this is a demographic that currently is not being very well tailored to,” Bryan said.

People 60 and older constitute the fastest growing group of cannabis users in the U.S. A new study explores why, and what doctors and retailers can do to better serve them.

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6 things �鶹��Ѱ��Boulder research has taught us about cannabis

Lisa Marshall — Mon, 20 Apr 2026 18:14:03 +0000

6 things �鶹��Ѱ��Boulder research has taught us about cannabis Lisa Marshall Mon, 04/20/2026 - 12:14

Lisa Marshall

It’s Cannabis Awareness Month, and few universities have done as much as �鶹��Ѱ��Boulder to advance our scientific understanding of Cannabis sativa.

In 2017, researchers at the Center for Health & Neuroscience, Genes & Environment (CUChange) unveiled the nation’s first mobile laboratory, a.k.a. Cannavan, for studying the plant’s real-time impact on users.

Since cannabis remains illegal at the federal level, university researchers are not permitted to possess or provide commercially available cannabis products for research. The van—now a fleet of three Dodge/Mercedes sprinter vans—gets around that scientific obstacle, enabling research teams to drive to the off-campus home of study subjects who have already consumed their own cannabis products and invite them in for everything from blood and cognitive tests to roadside sobriety tests.

Professional research assistants Paige Xiaoying Phillips (left) and Gray MacDonald pose for a photo inside the mobile pharmacology lab, aka the Cannavan, at �鶹��Ѱ��Boulder.

This, and other research efforts across campus have contributed dozens of scientific studies to the field at a time when all but 10 states allow use of cannabis for medical purposes and half permit recreational use.

“As one of the first groups in the country to study real-world cannabis use with rigorous, ecologically valid methods, we’ve had the opportunity to lead work that helps bridge science and lived experience-so individuals, clinicians, and policymakers can make more informed, evidence-based decisions,” said associate professor Cinnamon Bidwell, who co-leads CUChange with Psychology Professor Angela Bryan.

Here’s a snapshot at what �鶹��Ѱ��research has revealed so far, and what scientists are working to learn.

Don’t always trust the labels

Nearly half of cannabis flower products are inaccurately labeled when it comes to potency, with most showing they contain more THC than they really do, according to a study published in the journal Scientific Reports. Meanwhile, labels on cannabis concentrates like oils and waxes tend to be accurate, with 96% shown to match what’s inside. Read more.

Weed can make workouts more fun but it does not enhance performance

A study of 42 runners, published in the journal Sports Medicine, shows THC and CBD products can increase positive mood and enjoyment during exercise, but THC can also increase heart rate and make exercise feel more effortful. Read more.

CBD can ease anxiety without the risks that can come with THC

The study of 300 people, published in the journal Cannabis and Cannabinoid Research, was the first randomized trial to examine how legal, commercially available cannabis impacts anxiety symptoms.

The study comes as one in five U.S. adults suffer from an anxiety disorder and prescriptions for anti-anxiety medications are on the rise. Read more.

Cannabis may ease ‘chemo brain’ and improve sleep among cancer patients

The study, published in the journal Exploration in Medicine, is among the first to assess how cannabis bought over the counter at dispensaries—rather than government-supplied or synthetic varieties—impacts cancer symptoms or chemotherapy side effects. It also sheds light on the wide variety of products cancer patients use now that marijuana is legal in most states. Read more.

Can taking CBD help people use less weed? A new study explores

An ongoing �鶹��Ѱ��Boulder study is exploring whether taking cannabidiol (CBD), a non-intoxicating ingredient in the Cannabis sativa plant, can help people with an unhealthy dependency smoke less weed or give it up entirely. Read more and watch a video.

A THC breathalyzer? It’s in the works

Fourteen years after Colorado and Washington became the first U.S. states to legalize recreational cannabis, police still lack a reliable method for detecting whether someone smoked a joint or ate a gummy recently and whether they are too impaired to drive.

Researchers at �鶹��Ѱ��Boulder hope to help solve that problem, using a laboratory on wheels and state-of-the-art chemistry to map the peaks and declines of a cannabis high in real time. Read more.

Since 2017, researchers at the Center for Health & Neuroscience, Genes & Environment (CUChange) have been using a mobile van, a.k.a. the Cannavan, to study the real-time impacts of cannabis. In recognition of Cannabis Awareness Month, here's a look at what they've learned.

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Mental, physical illnesses often go hand in hand. Genetic study helps explain why

Lisa Marshall — Wed, 08 Apr 2026 16:22:46 +0000

Mental, physical illnesses often go hand in hand. Genetic study helps explain why Lisa Marshall Wed, 04/08/2026 - 10:22

Lisa Marshall

For centuries, mental illness and physical disease have been viewed as two distinct categories, each with its own field of study, its own doctors, and its own menu of treatments.

New �鶹��Ѱ��Boulder research calls that age-old dichotomy into question, showing that the same chunks of DNA that underly psychiatric disorders like depression, PTSD and ADHD are associated with risk of a host of physical ailments, too.

The study of nearly two million people, published in the journal Nature Communications, sheds light on just how often, and why, psychiatric and physical diseases go hand in hand. It could ultimately pave the way for new therapies that address both, the authors said.

Andrew Grotzinger

“The surprising finding here is not that psychiatric disorders and medical disorders are linked, but rather, how much they are linked,” said senior author Andrew Grotzinger, assistant professor of psychology and neuroscience. “At the genetic level, we found that there is so much overlap they are really not two different classes of diseases at all.”

Diseases come in pairs

Grotzinger’s previous research has shown that people with one psychiatric disorder often have many (41% meet the criteria of four or more), likely due to shared genetic factors. Physical disorders also come in groups, with 38% of the global population having two or more chronic conditions.

Only recently have scientists begun to explore how often physical and psychiatric disorders coincide. One recent study, looking at medical records of Danish citizens, found that having a mental health disorder boosted risk of a physical disease by 37%, with some psychiatric disorders increasing risk of some physical disorders by nearly 400%. People with depression, studies show, are 1.5 times as likely as those without depression to develop heart disease.

“In the clinic, you rarely see someone with just one condition walk into a room,” said first author Jeremy Lawrence, a doctoral candidate in clinical psychology. “If we can better understand the cross-talk between these conditions, we can do a better job helping the whole patient.”

To determine just how common these physical-mental combinations are, Grotzinger and Lawrence analyzed genetic material and health information from 1.9 million people.

They looked at which chunks of DNA are associated with 73 physical outcomes across eight medical domains (neurological, respiratory, circulatory, digestive, endocrine/metabolic, genitourinary, musculoskeletal, and cancer). Then they did the same with 13 psychiatric disorders across five categories (compulsive, psychotic/thought, neurodevelopmental, internalizing, and substance abuse).

When comparing physical and mental disorders, the genetic risk factors overlapped 42% of the time.

“We found that, at the genetic level, the shared risk between psychiatric and non-psychiatric medical disease is pervasive and substantial,” said Lawrence.

Neurodevelopmental disorders, like ADHD, were most likely to be associated with physical illnesses. In the case of ADHD, it had more in common, genetically, with physical diseases than with other psychiatric diseases.

Major depression, PTSD and substance use disorders also had high levels of shared risk with physical illnesses. In contrast, compulsive disorders like obsessive compulsive disorder and Tourette syndrome, were seldom associated with physical illnesses and seemed to have a protective effect when it came to digestive disorders.

Some specific diseases tended to go together.

Jeremy Lawrence

For instance, schizophrenia tended to pair with gastrointestinal problems; bipolar disorder tended to pair with genitourinary disorders and sleep problems. Depression and anxiety tended to pair with cardiovascular disease.

The chicken or the egg?

Lawrence noted that having a mental illness, like depression, could lead to behaviors—like eating poorly or leading a sedentary lifestyle—that precipitate poor physical health. In other cases, like a cancer diagnosis, physical illness could boost risk of mental illnesses like depression. In some cases, a common chunk of DNA may independently boost risk of both a physical illness and a mental illness.

Lawrence imagines a day when therapies could be developed that hit both physical and mental health targets at once.

He pointed to GLP-1 agonists—originally developed for diabetes, then prescribed for weight loss, and now showing promise for use in substance abuse disorders—as an example of how drugs meant for physical disease are making their way into the mental health realm.

Genetics could also be used to predict which groupings of diseases across the mental and physical spectrums a person is susceptible to so they can intervene early.

For now, the research shows that addressing mental illness can go a long way in improving overall health, said Grotzinger. It could also help break down the silos between psychology and general medicine.

“You can ask someone to spit in a tube or put a blood pressure cuff on to diagnose physical illness, but in many ways, we don’t have that for psychiatric disorders, so some have viewed them as more esoteric and less tangible,” said Grotzinger. “Psychiatric disorders are just as real as any medical disease. Our findings help make that argument.”

An analysis of DNA from two million people shows that that the same genetic architecture that underlies things like depression, ADHD and substance abuse also boosts risk of a host of physical illnesses.

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A simple shot shows promise to reverse osteoarthritis within weeks

Lisa Marshall — Mon, 06 Apr 2026 14:19:06 +0000

A simple shot shows promise to reverse osteoarthritis within weeks Lisa Marshall Mon, 04/06/2026 - 08:19

Lisa Marshall

Stephanie Bryant, professor of chemical and biological engineering, in her lab at the BioFrontiers Institute on the �鶹��Ѱ��Boulder campus. Bryant and a multidisciplinary team have developed a suite of new therapies that prompt aging or damaged joints to repair themselves within weeks. Photos by Casey Cass/�鶹��Ѱ��Boulder.

A research team including scientists and engineers from �鶹��Ѱ��Boulder, �鶹��Ѱ��Anschutz and Colorado State University has developed a suite of new therapies that prompt aging or damaged joints to repair themselves within weeks, according to animal studies.

The new osteoarthritis treatments include a single, regenerative injection to a joint and a biomaterial repair kit that recruits the body’s own cells to patch holes in damaged cartilage.

To expedite the research, the federal Advanced Research Projects Agency for Health (ARPA-H) announced this week that the multidisciplinary team will advance to the next phase of the up to $33.5 million project. The project is under the ARPA-H Novel Innovations for Tissue Regeneration in Osteoarthritis (NITRO) program. NITRO is led by ARPA-H Program Manager Dr. Ross Uhrich.

“In two years, we were able to go from a moonshot idea to developing these therapies to demonstrating that they reverse osteoarthritis in animals,” said principal investigator Stephanie Bryant, professor of chemical and biological engineering at �鶹��Ѱ��Boulder. “Our goal is not just to treat pain and halt progression, but to end this disease.”

Stephanie Bryant works with Laurel Stefani, a biomedical engineering doctoral candidate from Richardson, Texas.

Osteoarthritis is the third most common disease in the U.S., impacting roughly one in six people over age 30 worldwide. It causes cartilage, the buffering tissue that keeps bones from grinding together, to decay. Over time, it can damage bone too, reshaping the joint and making movement excruciating.

Patients are generally limited to two options: Treat the pain or replace the joint. There is no cure. To move toward one, the Colorado team is taking two approaches.

The first centers around repurposing an existing drug already approved by the Food and Drug Administration and applying it to treat osteoarthritis. Bryant, a materials scientist, and her colleagues developed a patented particle delivery system that can be injected into the joint and provide intermittent bursts of the drug for months.

For those with significant lesions in cartilage or bone, the team also developed a cocktail of engineered proteins that can be injected arthroscopically and cured into place, where it recruits the body’s own progenitor cells to patch the gap.

When the team used the injection to treat animals with arthritic joints and injuries, the joints returned to a healthy state within four to eight weeks. When they patched holes in bone or cartilage, they saw “full regeneration and repair of the defect,” said Bryant. In human cells derived from patients undergoing joint replacements, the therapies had a clear regenerative effect.

NITRO was the inaugural program of ARPA-H, created to develop “minimally invasive therapeutics that fully regenerate damaged joints.” Two years ago, NITRO awarded the Colorado team up to $33.5 million, contingent on positive results, to pursue this goal.

With phase one successfully complete, the team is now advancing to phase two.

“It’s super exciting to be a part of the very first program of ARPA-H and to be one of the first teams to advance to the second phase,” said Bryant.

Dr. Evalina Burger, professor and chair of the Department of Orthopedics at �鶹��Ѱ��Anschutz, said she has seen osteoarthritis afflict everyone from grandparents who can’t comb their hair without shoulder pain to runners and hockey players who had to give up the sport they love due to knee or back pain.

“At the moment, the options for many patients are either a massive, expensive surgery or nothing. There’s not a lot in between,” said Burger, who has been following the team’s research with interest. “That’s why ARPA-H is so important.”

She and Bryant imagine a day when those in the earlier stages of the disease could access an affordable single-dose therapy to keep their joints healthy for years. Those with injured tissue could have it fixed in a single doctor’s visit with a quick recovery.

The team hopes to publish their animal findings in a peer reviewed journal later this year and has formed a company, Renovare Therapeutics Inc. to move toward commercialization.

If future studies go according to plan, Bryant anticipates clinical trials could be underway in as soon as 18 months.

“This could be a real game-changer for patients,” said Bryant.

A �鶹��Ѱ��Boulder-led team has developed a suite of new therapies aimed at reversing osteoarthritis in a single injection. With animal studies showing promise and funding from the Advanced Research Projects Agency for Health extended, the team could be ready for human trials by 2028.

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Can concussions cause fear of movement?

Megan M Rogers — Mon, 23 Mar 2026 17:42:11 +0000

Can concussions cause fear of movement? Megan M Rogers Mon, 03/23/2026 - 11:42

Colorado Arts and Sciences Magazine

�鶹��Ѱ��Boulder neuroscience student Alexander Wiegman's research finds that a history of concussions doesn't necessarily lead to later kinesiophobia.

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Python blood could hold the secret to healthy weight loss

Lisa Marshall — Thu, 19 Mar 2026 20:23:30 +0000

Python blood could hold the secret to healthy weight loss Lisa Marshall Thu, 03/19/2026 - 14:23

Lisa Marshall

A ball python. Photos by Patrick Campbell/�鶹��Ѱ��Boulder

�鶹��Ѱ��Boulder researchers have discovered an appetite-suppressing compound in python blood that helps the snakes consume enormous meals and go months without eating yet remain metabolically healthy.

The research, a collaboration with scientists at Stanford Medicine and Baylor universities, could inform new weight loss therapies that promote satiety without the nausea and muscle loss that can come with existing drugs.

Professor Leslie leinwand, left, and PhD candidate Skip Maas look on at Maas's pet pythons during their visit to the lab. In addition to keeping pet pythons, Maas studies python metabolism.

The findings were published in the journal Natural Metabolism on March 19.

“This is a perfect example of nature-inspired biology,” said senior author Leslie Leinwand, a distinguished professor of Molecular, Cellular and Developmental Biology who has been studying pythons in her lab for two decades. “You look at extraordinary animals that can do things that you and I and other mammals can’t do, and you try to harness that for therapeutic interventions.”

Metabolic superheroes

Pythons can grow as big as a telephone pole, swallow an antelope whole, and go months or even years without eating—all while maintaining a healthy heart and plenty of muscle mass. In the hours after they eat, Leinwand’s research has shown, their heart expands 25% and their metabolism speeds up 4,000-fold to help them digest their meal.

To get a better sense of what makes these superpowers possible, Leinwand teamed up with Jonathan Long, an associate professor of pathology at Stanford School of Medicine who studies metabolic byproducts in the blood, or metabolites, to learn how mammals take in and expend energy.

Long’s lab recently examined the blood of another curious creature—the racehorse—for insight on how the animals can endure those all-out sprints.

“If we truly want to understand metabolism, we need to go beyond looking at mice and people and look at the greatest metabolic extremes nature has to offer,” said Long.

For the new study, the team measured blood samples from ball pythons and Burmese pythons, fed once every 28 days, immediately after they ate a meal.

In all, they found 208 metabolites that increased significantly after the pythons ate. One molecule, called para-tyramine-O-sulfate (pTOS) soared 1,000-fold.

Further studies, done with Baylor University researchers, showed that when they gave high doses of pTOS to obese or lean mice, it acted on the hypothalamus, the appetite center of the brain, prompting weight loss without causing gastrointestinal problems, muscle loss or declines in energy.

The study found that pTOS, which is produced by the snake’s gut bacteria, is not present in mice naturally. It is present in human urine at low levels and does increase somewhat after a meal.

But because most research is done in mice or rats, pTOS has been overlooked.

“We’ve basically discovered an appetite suppressant that works in mice without some of the side-effects that GLP-1 drugs have,” said Leinwand, referring to drugs like Ozempic and Wegovy, which act on the hormone glucagon-like petide-1 (GLP-1).

Nature-inspired weight loss therapies

Leinwand noted that these new drugs were inspired by another reptile, the Gila monster. Gila monster venom contains a hormone similar to human GLP-1.

Those drugs are now used by millions, but studies show that as as many as half of people who use them stop taking them within a year.

“We believe there is still room for therapeutic growth in this market,” said Leinwand.

She, Long and her �鶹��Ѱ��Boulder colleagues have formed a start-up, Arkana Therapeutics, to work toward commercializing some of the lessons they are learning from pythons.

They imagine a day when chemically synthesized analogs of the rare metabolites found in pythons could be turned into therapies to help people.

Ball pythons. Credit: Patrick Campbell/�鶹��Ѱ��Boulder

Weight loss isn’t the only therapeutic goal they are eyeing.

Age-related muscle loss, or sarcopenia, impacts nearly everyone to some degree as they get older, and people who have health problems that make it hard for them to exercise are hit particularly hard. To date, there are no therapies to halt or reverse sarcopenia.

The snakes may offer insight into how to do that, too, Leinwand said.

In future research, the team hopes to explore how pTOS works in people and catalogue the function of the other metabolites that increase after pythons eat. Some metabolites the researchers identified in their study soar by 500% to 800%.

“We’re not stopping with just this one metabolite,” said Leinwand. “There’s a lot more to be learned.”

Scientists have discovered a novel metabolite in pythons that quells appetite without causing gastrointestinal side effects or muscle wasting. The findings could lead to new weight loss therapies with fewer side effects.

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Study probes 'new normal' for older adults post-COVID

Megan M Rogers — Wed, 18 Mar 2026 18:49:55 +0000

Study probes 'new normal' for older adults post-COVID Megan M Rogers Wed, 03/18/2026 - 12:49

Colorado Arts and Sciences Magazine

Researchers from �鶹��Ѱ��Boulder have found that the pandemic reshaped how people age 55 and older interact with their communities while highlighting the importance of "social infrastructure."

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�鶹��Ѱ��researchers study potential links between hearing loss and dementia

Megan M Rogers — Tue, 17 Mar 2026 16:45:55 +0000

�鶹��Ѱ��researchers study potential links between hearing loss and dementia Megan M Rogers Tue, 03/17/2026 - 10:45

Coloradan , Lisa Marshall

A �鶹��Ѱ��Boulder lab is exploring how age-related hearing loss rewires the brain—and whether hearing aids can undo the damage.

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