Medicaid funding for addiction treatment hasn’t curbed overdose deaths

OHSU research suggest Medicaid waivers may be necessary but insufficient to tackle the national opioid epidemic

Oregon Health & Science University

For generations, the federal government has largely refrained from paying for mental health and substance use treatment in large residential facilities.

That changed in 2015 when, in response to increasing overdose deaths nationwide from illicit drugs, the federal government allowed states to waive a longstanding prohibition against using federal Medicaid funding for services in so-called institutions of mental diseases. In turn, states were required to improve their addiction care with an emphasis on increasing treatment with medications.

Yet a new study by researchers at Oregon Health & Science University finds no overall benefit in terms of increased treatment or decrease in nonfatal overdoses among the 17 states that received those waivers between 2017 and 2019, compared with 18 that did not. Medicaid is a joint federal-state health insurance program that covers about 90 million Americans, although not every state extends Medicaid coverage to all low-income adults.

The study published today in this month’s edition of the journal Health Affairs.

“The waivers have been important to update Medicaid’s program to treat opioid use disorder, however they alone do not appear to have meaningfully improved the situation in terms of uptake of medication to treat opioid use disorders or in reducing overdoses,” said lead author Stephan Lindner, Ph.D., associate professor in the OHSU Center for Health Systems Effectiveness and a faculty member of the OHSU-Portland State University School of Public Health.

Lindner noted that the null result highlights the fact that the waivers may be necessary but are clearly insufficient to bring the nation’s overdose epidemic under control.

“These waivers started about 10 years ago,” he said. “Back then, about 50,000 people died of drug overdoses per year. Fast forward 10 years, and more than 100,000 people die of drug overdoses in the United States per year.

“We have made some progress in addressing the opioid crisis, but we need more substantial action at the federal level to make sure all people with opioid use disorder get the treatment they need.”

Waivers aren’t enough, but Lindner pointed to several initiatives backed by research and law that could better address the nation’s illicit drug overdose crisis:

• Treatment across the full spectrum of care. A federal law sponsored by former U.S. Rep. Greg Walden, R-Hood River, in 2018 already requires states to cover the three FDA-approved medications to treat opioid use disorder (methadone, buprenorphine and naltrexone), however Lindner said enforcement may have been lax.
• Improve access to methadone. Research, including a series of evidence reviews conducted at OHSU, recommends easing access to methadone, which has historically been dispensed only in specialized clinics. A recent study by OHSU physician Honora Englander, M.D., found that 87% of people with opioid use disorder in France received access to methadone compared with less than 20% in the United States.
• Step up distribution of life-saving naloxone. OHSU recently hosted a series of events promoting the widespread distribution of naloxone to reverse overdoses, especially to young people.
• Increase access to buprenorphine. Previous research by Lindner found that access to buprenorphine varied widely between U.S. states. Stigma remains a hurdle in medical settings, including pharmacies.

In addition to Lindner, co-authors included Kyle Hart, M.S., Brynna Manibusan, M.S., and Kirbee Johnston, M.P.H., of the OHSU Center for Health Systems Effectiveness; Dennis McCarty, Ph.D., professor emeritus of public health and preventive medicine in the OHSU School of Medicine and the OHSU-PSU School of Public Health; and K. John McConnell, Ph.D., director of the OHSU Center for Health Systems Effectiveness and a faculty member of the OHSU-PSU School of Public Health.

This research was supported by the National Institute on Drug Abuse of the National Institutes of Health, grant number R01DA052388. The content is solely the responsibility of the authors and does not necessarily represent the official views of the NIH.

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Journal

Health Affairs

DOI

10.1377/hlthaff.2024.00461 

Method of Research

Data/statistical analysis

Subject of Research

People

Article Title

Effects Of Medicaid Waivers On Use Of Medications For Opioid Use Disorder And Nonfatal Overdoses In 17 States

Article Publication Date

4-Nov-2024

 

People are more agile than they think

Ruhr-University Bochum

 

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A wrist can be bent much further than we imagine.

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Credit: RUB, Kramer

People can bend their wrist further than they think. This is what researchers from Ruhr University Bochum, Germany, and the Université catholique de Louvain, Belgium, have discovered. They asked 84 people to estimate how far they could move their hand in different directions. The participants systematically underestimated the mobility of their wrist. “The brain obviously doesn't have an accurate image of the body movement limits,” sums up Bochum neuroscientist Dr. Artur Pilacinski. He describes the results together with Antoine Vandenberghe, Gabriella Andrietta and Professor Gilles Vannuscorps in the journal “Communications Psychology” from November 1, 2024.

People have a distorted body schema

“Previous studies by other groups have already shown that people have a distorted body schema,” explains Pilacinski. “For example, they systematically underestimate the weight or size of their hands. We were interested in whether there is a similar bias for body movements.”

The researchers examined wrist movements in four different directions. Some of the participants were asked to mentally visualize the various hand movements. They indicated on an angular ruler how far they expected to be able to move. The other participants were shown various positions on the angular ruler and had to decide for each of them whether or not they could reach it by bending their wrist. Finally, the actual wrist mobility was measured in the four directions: Participants had to bend their hand inwards and outwards towards their forearm and tilt their wrist towards their thumb or little finger.

Systematically underestimated

For three of these four hand movements, there was a significant difference between the assumed and actual mobility. The participants underestimated their mobility by an average of at least ten degrees. The only exception was the movement towards the thumb. “Presumably because the wrist is the least flexible in this direction and the difference between assumed and actual mobility was too small to be measurable with our method,” explains Artur Pilacinski.

As the study reveals, people are unaware of the true limits of their mobility. “We can only speculate about the reasons,” says Pilacinski. “The most likely explanation is that this bias protects us from injury because it prevents us from overshooting. This way, we may have to make small corrections during our movements, but that protects our muscles, tendons and ligaments.”

The researchers expect a potential benefit of this finding for sports or rehabilitation, where people are deliberately pushed to the limits of their mobility. Knowing that the presumed limit is not the real limit could help to better imagine our movement limits and ultimately achieve better mobility.

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Journal

Communications Psychology

DOI

10.1038/s44271-024-00153-x 

Article Title

Humans Underestimate the Movement Range of Their Own Hands

Article Publication Date

1-Nov-2024

Virginia Tech researchers find menthol restrictions may drive smokers to healthier alternatives

Fralin Biomedical Research Institute at VTC scientists find smokers may shift to nicotine replacement options with the right mix of products and pricing.

 News Release 4-Nov-2024
Virginia Tech

 

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Roberta Freitas-Lemos, assistant professor at the Fralin Biomedical Research Institute at VTC, was part of a team that analyzed preferences for menthol-flavored cigarettes and e-cigarettes and the effect of filter ventilation options on purchase decisions. The research was published in the October issue of Drug and Alcohol Dependence.

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Credit: Clayton Metz/Virginia Tech

Nationwide, fewer people smoke than did a decade ago, but the proportion who smoke menthol-flavored cigarettes is on the rise.

More than 9 million adults, or about 32 percent of all smokers, use menthol cigarettes, according to the Centers for Disease Control and Prevention. In Virginia, the proportion stands higher, at 38 percent.

A team of researchers including Roberta Freitas-Lemos, assistant professor at Virginia Tech’s Fralin Biomedical Research Institute at VTC, found that if menthol products were unavailable, smokers found replacement therapies such as nicotine gum and lozenges were practical alternatives, potentially improving health outcomes for people who use menthol cigarettes.

The findings come from a study that examined what products adult smokers purchased in an experimental marketplace that adjusted prices and availability of tobacco and nicotine products.

“We were trying to understand how different flavor policies interact, the role of cigarette filter ventilation, and how different types of smokers would respond to those policies,” said Freitas-Lemos, who is with both the institute’s Center for Health Behaviors Research and Cancer Research Center in Roanoke. “We wanted to understand the effect of restrictions on purchases.”

The study, which published in the October issue of Drug and Alcohol Dependence, analyzed preferences for menthol-flavored cigarettes and e-cigarettes and the effect of filter ventilation options on purchase decisions.

What they did

Researchers analyzed data from 172 people who exclusively smoke cigarettes — 76 of whom smoke menthol and 96 non-menthol cigarettes — and 91 people who use multiple tobacco products. Participants were older than 21, smoked at least 10 cigarettes daily, and had smoked a minimum of 100 cigarettes in their lifetime.

The volunteers were asked to complete trial purchases in the Experimental Tobacco Marketplace, a tool addiction recovery research expert Warren Bickel created to study the effects of tax and regulatory policies on health behaviors. Bickel, who died in September, was a professor at the Fralin Biomedical Research Institute, director of its Addiction Recovery Research Center and Center for Health Behaviors Research, and one of the study’s principal investigators.

In the marketplace, participants used an account in an online platform to purchase tobacco and nicotine products, including replacement therapies. Options were tailored to each participant’s preferred flavors and nicotine concentrations, and they were given an account balance designed to reflect their personal budget constraints.

Research participants shopped for products under different market conditions — with varying prices and restricted or unrestricted cigarette or e-cigarette flavors.

What they found

When menthol cigarettes were not available, smokers who preferred menthol cigarettes were less willing to purchase any type of cigarettes and more willing to purchase products such as nicotine gum and other replacement therapies.

In addition, cigarette smokers who prefer menthol products were less likely to substitute e-cigarettes when menthol flavored e-cigarettes were also restricted.

For individuals in the study who use multiple tobacco products, restricting flavors had no impact on their purchases.

The study also found higher demand for cigarettes among smokers who preferred high-ventilation cigarettes — cigarettes with filter holes for airflow.

Why it matters

Menthol, a compound found in plants such as peppermint, is added to tobacco products to make them more appealing. In addition, menthol enhances nicotine’s effects and can make them more addictive.

Tobacco product design features, including flavors and cigarette filter ventilation, are subject to regulation by the Food and Drug Administration, which is why the study examined the effects of cigarette and e-cigarette flavors on demand and substitution by preferred cigarette flavor and ventilation.

An area that requires more investigation, Freitas-Lemos said, is the relationship between cigarette filter ventilation and smoking behavior, which could be connected to smokers’ perception of their cigarettes.

“Cigarettes with ventilation are milder and people think they are less harmful, but it is a false perception,” said Freitas-Lemos, who also holds an appointment as an assistant professor of psychology in the College of Science. One study showed higher rates of lung adenocarcinoma among people who smoke ventilated cigarettes. 

“It could be that people who smoke ventilated cigarettes are more responsive to one ban than another,” said Freitas-Lemos, who noted that more research is needed to better understand how perception and ventilation influence behavior.

“I think the most important conclusion from this study is that we can improve health outcomes by emphasizing policies that reduce sales of flavored products and increase accessibility of nicotine replacement therapies,” Freitas-Lemos said.

 

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Journal

Drug and Alcohol Dependence

DOI

10.1016/j.drugalcdep.2024.112422 

Method of Research

Experimental study

Subject of Research

People

Article Title

Restrictions of cigarette and e-cigarette flavor and filter ventilation on demand and substitution in the Experimental Tobacco Marketplace

COI Statement

Although the following activities/relationships do not create a conflict of interest pertaining to this manuscript, in the interest of full disclosure, Dr. Bickel would like to report the following: W. K. Bickel is a principal of HealthSim, LLC; BEAM Diagnostics, Inc.; and Red 5 Group, LLC. In addition, he serves on the scientific advisory board for Ria Health; and serves as a consultant for Lumanity and AlphaSights. Dr. Tegge works on a project supported by Indivior, Inc. The other authors report no conflict of interest.

Midwakh pipe smoking posing ‘significant’ health problems in UAE, scientists find

University of Sharjah

A traditional type of tobacco smoking locally known as midwakh is causing severe health problems and nicotine dependency among users in the United Arab Emirates (UAE), scientists from the University of Sharjah reported in a recent study.

The research’s findings are based on a quasi-experimental before-and-after study of 103 young male midwakh smokers in the UAE.

Midawkh is a traditional smoking practice involving a smoking pipe of Arabian origin and a mixture of tobacco from Iran. It is prevalent in Arabian Peninsula which includes the UAE, Oman, Qatar, Bahrain, Kuwait, and Saudi Arabia.

The Iranian element is represented in an imported sifted loose tobacco mixture locally known as dokha or dizziness that contains bark herbs and aromatic leaves.

“Midwakh smoking is deeply ingrained in UAE tradition but poses significant adverse health outcomes and nicotine dependency,” the scientists write.

Compared to shisha pipe smoking, another Middle Eastern traditional smoking practice, which has migrated to many western countries, the midwakh is more intense and even stronger.

Prof. Basema Saddik, the study’s lead author, said while global smoking rates were declining, the Middle East faced unique challenges. “Population growth and a younger demographic in the Middle East are leading to sustained high numbers of smokers despite global declines in smoking prevalence.

“This is particularly critical for the UAE, where vaping, shisha, midwakh and other alternative tobacco products are becoming increasingly popular among youth, potentially leading to significant health issues later.”

Although the results of the study are confined to data collected in the UAE, Prof. Saddik said the findings were bound to reverberate in countries where midwakh is common among smoking populations. 

“While the scope of this study is regional, its implications are significant and timely, especially as we continue to address nicotine dependence trends in this population.”

The research’s data collection included surveys featuring the Hooked-on Nicotine checklist (HONC), clinical measurements, and pre/post-smoking saliva samples. The scientists note, “Midwakh smoking adversely affects clinical measurements, with early start correlating with higher nicotine dependency, worsened by using multiple tobacco products.”

Prof. Saddik, who is director of Sharjah University’s Center of Excellence for Public Health, said the study’s findings showed that midwakh users “often develop early signs of nicotine dependence and reported various clinical issues, including elevated carbon monoxide and cotinine levels, which are indicators of harmful tobacco exposure.”

The authors’ preliminary findings pointed to severe health risks related to midwakh smoking particularly the young generation in the UAE. The study reported that “33% of midwakh smokers were under 21 years, 68% had below undergrad education, and household incomes over 15,000 AED (approx. $4000) monthly.  Smoking initiation was as early as 10 years.

“Smoking habits revealed 37% exclusive midwakh, 54% midwakh with e-cigarettes, 21% with shisha, and 34% with cigarettes. Post-smoking clinical measurements showed significant increases in blood pressure, heart, pulse and respiratory rates, and carbon monoxide levels.”

Prof. Saddik attributed the widespread use of midwakh in Arabia and specifically in the UAE to smokers mistakenly believing that the herbs and aromatic leaves in the tobacco – which lure many users – make it safer or less harmful than other cigarettes, leading to higher rates of initiation and dependence.

Research shows that a midwakh session, in terms of nicotine intake, can be the equivalent of smoking up to ten cigarettes, and in fact with much higher nicotine and tar levels. The diseases associated with midwakh smoking are no different from those caused by cigarette smoking including coronary artery disease, lung cancer and chronic obstructive pulmonary disease.

Prof. Saddik went on, “Clinical assessments also revealed negative health indicators, including elevated carbon monoxide levels which suggest that without intervention, a large portion of the UAE’s youth could face severe long-term health consequences.”

“Addressing these issues now with targeted prevention programs and regulations on alternative tobacco products is essential to change these projected outcomes.”

Prof. Saddik describes the findings of the study as “a wake-up call” for policy makers in the UAE and other countries with midwakh smokers to implement “strong smoking cessation policies and public education initiatives, particularly aimed at youth.

“The significance of our midwakh study lies in the immediate clinical impacts observed among users, with findings showing high nicotine dependency and harmful respiratory indicators.”

Prof. Saddik said the research had practical implications for health policy makers. The findings, she said, served as “a warning and a guide to protect future generations” in countries like the UAE “where alternative tobacco products are gaining popularity among youth.

“While alternative products like midwakh are often perceived as less addictive, our research reveals high nicotine levels and significant dependency among young users, ultimately impacting their health and future quality of life.”

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Journal

European Journal of Public Health

DOI

10.1093/eurpub/ckae144.397 

Method of Research

Survey

Subject of Research

People

Article Title

Tradition to Concern: Health Risks and Nicotine Dependence of Midwakh Use in Young Males in the UAE

Article Publication Date

3-Nov-2024

 

New study reveals blood sugar control is a key factor in slowing brain aging, highlighting the benefits of the Mediterranean diet

Ben-Gurion University of the Negev

BEER-SHEVA, Israel, November 4, 2024 – Age-related brain atrophy, the gradual loss of neurons and shrinkage of brain tissue, is a natural part of aging, which can lead to cognitive decline and other neurological issues. While so far aging cannot be prevented, recent research from an 18-month dietary intervention offers hope that lifestyle and dietary changes can slow brain aging. A new international study, led by Ben-Gurion University of the Negev as part of the DIRECT PLUS Brain MRI trial, has brought to light how blood sugar control can significantly impact brain health.

Brain age, as evaluated by MRI measurements of the hippocampus and lateral ventricles, reflects the biological aging of the brain, which can differ from a person's chronological age. Chronological age is the number of years lived, while brain age indicates the brain's actual health. Typically, as we age, the hippocampus shrinks and the lateral ventricles expand, serving as markers of brain aging. Some individuals have a brain age younger or older than their chronological age. A younger brain age suggests better cognitive health, while an older brain age may indicate accelerated aging and increased risk of cognitive decline.

The study, which was published recently in The American Journal of Clinical Nutrition 2024 https://www.sciencedirect.com/science/article/abs/pii/S0002916524007457 , was conducted by an international team of brain and nutrition experts, including researchers from Ben-Gurion University, Harvard University, Leipzig University, and more. The research was primarily carried out by Ph.D. student Dafna Pachter and overseen by Prof. Iris Shai, along with several international collaborators.

A previous study published two years ago (American Journal of Clinical Nutrition 2022 https://pubmed.ncbi.nlm.nih.gov/35021194/), reported that Mediterranean (MED) and green-MED diets significantly attenuated age-related brain atrophy by ∼50% within 18 months.

In the current study, the researchers aimed to understand the mechanism by which the slowing of brain atrophy occurs.

The study found that a decline in HbA1c, and key markers of long-term blood sugar levels, are associated with significant positive changes in specific brain regions commonly affected by age-related atrophy. Brain MRI results showed that lower HbA1c levels corresponded to greater deviations in the thalamus, caudate nucleus, and cerebellum – areas crucial for cognitive function, motor control, and sensory processing. The study suggests that improved blood sugar control could be one of the most important factors in slowing down age-related brain changes.

The Green Mediterranean Diet Shows Promise

Earlier research has highlighted the benefits of the Green Mediterranean (Green-Med) diet, including better blood sugar control. The Green-Med diet is rich in polyphenols from plant-based sources like Mankai (a high-protein aquatic plant) and green tea, while being low in red and processed meats. The current study further strengthens this connection by suggesting that the Green-Med diet may not only support metabolic health but also exert protective effects on brain structure and function.

DIRECT PLUS Trial – One of the Largest Brain MRI intervention Studies in the World

The DIRECT PLUS trial, one of the longest and largest brain MRI studies conducted to date, involved approximately 300 participants who were divided into three dietary groups. Whole-brain MRI measurements were taken before and after the 18-month trial to track changes in brain health. The researchers used Hippocampal Occupancy (HOC), as a proxy for brain age which predicts future risk of dementia. HOC typically decreases with age. Interestingly, some participants exhibited a brain age either younger or older than their chronological age.

Using NeuroQuant, an FDA-authorized fully automated tool, the research team quantified and segmented the brain MRI-derived data. The study aimed to examine whether improved glycemic control and specific dietary components could slow down brain aging. The results indicated that participants who managed to improve their blood sugar levels and achieve normal glucose status experienced a more pronounced attenuation of brain aging. Notably, those who consumed higher amounts of green tea and Mankai duckweed shakes demonstrated the most significant improvements in both blood sugar levels and brain health.

Glycemic Control and Polyphenols: The Key to a Younger Brain Age?

The study’s lead researcher, Prof. Iris Shai, from Ben-Gurion University, an adjunct professor at Harvard University, and an Honorary Professor at Leipzig University, explains, “Maintaining low blood sugar levels, even within the normal range, shows promise for preserving a younger brain, especially when combined with a healthy diet and regular physical activity. Specifically, polyphenols found in plant-based foods may cross the blood-brain barrier and help reduce brain inflammation, which is crucial for memory”.

Dafna Pachter, a Ph.D. student and the first author of the paper, adds, "This trial offers a safe approach to potentially slow down our brain aging—by adopting the components of a green-Mediterranean diet."

A Pathway to Reducing Age-Related Cognitive Decline

This study is one of the first large-scale trials to directly link dietary changes, particularly those associated with the Green-Med diet, to improved glycemic control and slower brain aging. While further research is needed to fully understand the mechanisms at play, these results suggest a potential avenue for reducing the risk of age-related cognitive decline through relatively simple dietary adjustments.

The DIRECT PLUS trial was funded by grants from the German Research Foundation (DFG), Israel Ministry of Health, Israel Ministry of Science and Technology, and the California Walnuts Commission. None of the funding providers were involved in any stage of the design, conduct, or analysis of the study, nor did they have access to the study results before publication.

The researchers: Dafna Pachter, Alon Kaplan, Gal Tsaban, Hila Zelicha, Anat Yaskolka Meir, Ehud Rinott, Gidon Levakov, Moti Salti, Yoram Yovell, Sebastian Huhn, Frauke Beyer, Veronica Witte, Peter Kovacs, Martin von Bergen, Uta Ceglarek, Matthias Blüher, Michael Stumvoll, Frank B. Hu, Meir J. Stampfer, Alon Friedman, Ilan Shelef, Galia Avidan, and Iris Shai.

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Journal

American Journal of Clinical Nutrition

DOI

10.1016/j.ajcnut.2024.09.013 

Method of Research

Randomized controlled/clinical trial

Subject of Research

People

Article Title

Glycemic control contributes to the neuroprotective effects of Mediterranean and green-Mediterranean diets on brain age: the DIRECT PLUS brain-magnetic resonance imaging randomized controlled trial

 

Deaf male mosquitoes don’t mate

Knocking out a single gene rendered the insects deaf and males uninterested in mating

University of California - Santa Barbara

 

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If a male mosquito can’t hear a female. It’s as though she doesn’t exist.

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Credit: Matt Perko

Mosquitoes are much more blunt. Mating occurs for a few seconds in midair. And all it takes to woo a male is the sound of a female’s wingbeats. Imagine researchers’ surprise when a single change completely killed the mosquitoes’ libidos.

 

Now a study out of UC Santa Barbara reveals that this is really all there is to it. Researchers in Professor Craig Montell’s lab created deaf mosquitoes and found that the males had absolutely no interest in mating. “You could leave them together with the females for days, and they will not mate,” Montell said.

 

The dramatic change was simple to produce. “The absence of a single gene, trpVa, produced this profound effect on mosquito mating behavior,” explained co-lead author Dhananjay Thakur, a postdoctoral scholar in the Department of Molecular, Cellular, and Developmental Biology.

 

The results, published in the Proceedings of the National Academy of Sciences could have major implications for how we manage disease transmission by better controlling the populations of mosquito vectors, such as Aedes aegypti, that infect hundreds of millions of people every year with viruses that cause diseases.

 

Frisky skeeters

 

“On summer evenings, we often see swarms of mosquitoes gathered by the water or under streetlights. These gatherings are essentially mass mating events,” said co-lead author Yijin Wang, a former postdoc at UCSB. Although mosquitoes possess an extraordinary ability to reproduce, scientists still have a limited understanding of the molecular and neurological mechanisms at work.

 

Courtship for Aedes aegypti usually progresses like this: Females flap their wings at around 500 Hz. When males hear this, they take off, buzzing at about 800 Hz. The males also rapidly modulate this frequency when the ladies are around. Then there’s a quick midair rendezvous, and the paramours go their separate ways. Males are always scouting out new potential partners, but a female that’s successfully mated generally won’t do so again.

 

Montell and co-lead authors Yijin Wang, Thakur and Emma Duge suspected that hearing played a role in this behavior, so they investigated the insect’s auditory neurons. These lie at the base of the antennae in a structure called the Johnston’s organ. The antennae are magnificent multi-sensory apparatuses, chock-full of olfactory, mechanosensory and even thermal infrared sensilla, as Montell’s lab recently discovered. In the current study, the team focused on a particular sensory channel called TRPVa — and the corresponding gene, trpVa — which is the mosquito analogue of a channel required for hearing in fruit flies.

 

The team used CRISPR-Cas9 to knock out the gene that codes for TRPVa in Aedes aegypti mosquitoes. The resulting animals showed no reaction to sound. In fact, they found that sound elicited no electrical activity from neurons in the Johnston’s organ. The insects were truly deaf.

 

And when the authors placed deaf males in chambers with females … nothing happened. “If they can’t hear the female wingbeat, they’re not interested,” Montell said. Their hearing counterparts, on the other hand, wasted no time in getting busy: mating many times in the course of a few minutes.

 

A romantic soundtrack

 

Hearing is not only necessary for males to mate, it seems to be sufficient to rouse their desires. When the authors played the sound of female wingbeats to normal males, the males typically responded with abdominal thrusts. They were primed and ready for action. Deaf males barely twitched.

 

Females, however, were a different story. Deaf females still had some lust left in them. “The impact on the female is minimal, but the impact on the male is absolute,” Montell said. The team plans to study these differences in future work.

 

“I think the reason why our major finding is so shocking is because, in most organisms, mating behavior is dependent on a combination of several sensory cues,” said Duge, one of Montell’s doctoral students. “The fact that taking away a single sense can completely abolish mating is fascinating.”

 

And the authors believe that their results — the role of sound in mating and the function TRPVa plays in hearing — generalize to other species of mosquito.

 

Looking inside

 

A mosquito’s physiology reveals just how important hearing is to these insects. Male mosquitoes have the most auditory neurons of any known insect, Montell explained. Females have half as many. That’s still a lot, but hearing is much more crucial for males.

 

To identify which neurons express the trpVa gene, the authors added a gene coding for green fluorescent protein into the mosquito genome. They did this in a way such that the fluorescent protein was expressed indirectly under the control of the trpVa promoter. A promoter is a DNA sequence usually located at the start of a gene where enzymes bind to initiate transcription, in this case triggering the production of those green fluorescent proteins. Now the mutant mosquitoes would produce green fluorescent protein in all the places that normally would produce TRPVa. So the same mosquitoes provided test subjects for the experiment and a bright green map of TRPVa expression for the analysis.

 

Unsurprisingly, the team found that trpVa is expressed in the Johnston’s organ. And they could clearly follow the paths of auditory neurons from there into the brain, as well as see differences in these paths between male and female mosquitoes.

 

Hijacking mosquito courtship

 

Pathogens spread by the mosquito Aedes aegypti infect some 400 million people a year, of which about 100 million develop diseases like dengue, zika and yellow fever. This means that understanding its behavior and lifecycle can provide us tools and insights in disease prevention.

 

One potential method to control insect vectors is the sterile insect technique (SIT), which works by releasing a large number of sterile males to mate with females. In certain insects, like mosquitoes, successful mating prevents females from seeking other partners. And, if the female mates with a sterile male, she doesn’t actually produce offspring. In theory, this can suppress the population.

 

The technique works marvelously for certain agricultural pests like the California medfly. “The fact that you haven’t heard of this pest is a testament to how successful SIT is, because 30 years ago it was all over the news,” Montell said.

 

But the success of SIT in Aedes aegypti is limited by the competitiveness of the sterile males; they have to get to the females first for the ploy to work. Currently, the technique doesn’t cause enough suppression in mosquito populations for them to drop below the critical threshold and send the population plummeting. Given the central role of hearing in mosquito courtship, trpVa might provide a target for increasing the effectiveness of SIT. Montell’s lab is working on several ways to make sterile males that can outcompete their natural counterparts. Hopefully, the trick will be as straightforward as these unfussy lovers.

 

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Note to editors: Craig Montell is available at cmontell@ucsb.edu. Dhananjay Thakur is available at dhananjay.p.thakur@gmail.com. Emma Duge is available at emmaduge@ucsb.edu. Downloadable images can be found at https://news.ucsb.edu/2024/021664/deaf-male-mosquitoes-dont-mate.

 

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Journal

Proceedings of the National Academy of Sciences

 

Seal whiskers inspire engineer’s offshore turbine sensor design

University of Texas at Dallas

 

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Dr. Yaqing Jin, assistant professor of mechanical engineering at The University of Texas at Dallas, was recently named an Early-Career Research Fellow of the Gulf Research Program of the National Academies of Sciences, Engineering, and Medicine.

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Credit: The University of Texas at Dallas

In the dark ocean depths, seals hunt prey with their highly sensitive whiskers, which detect vibrations.

And it is the design of those hairs that inspired a University of Texas at Dallas researcher to develop a sensor to monitor turbulence in the deep ocean.

“The geometry of seal whiskers is not circular; the whisker’s shape is twisted cylinders,” said Dr. Yaqing Jin, assistant professor of mechanical engineering in the Erik Jonsson School of Engineering and Computer Science.

Jin was recently named an Early-Career Fellow of the Gulf Research Program of the National Academies of Sciences, Engineering, and Medicine for his research on offshore wind turbine safety. He is one of five fellows joining the Offshore Energy Safety Track, where their work will focus on contributing to the understanding, management and reduction of systemic risk in offshore energy activities.

“Those twisted cylinder shapes allow seals to sense changes in the ocean environment. The same shapes can help us design sensors in the lab to detect changes in water flow that could warn offshore wind turbine operators about dangerous conditions,” he said.

In his Fluids, Turbulence Control & Renewable Energy Lab, Jin and his research team test whisker-inspired designs in a 6-foot-long clear rectangular water channel. A pump moves water into the tube at different velocities to simulate the ocean environment. Jin and two UT Dallas co-authors published a 2023 study in the journal Physical Review Fluids analyzing how 3D-printed seal whiskers responded when a target changed speed or direction. The research was also featured in Physics magazine.

Sensors sensitive to vibration have advantages over the traditional underwater sensing technology using sound waves, which can disturb marine life, Jin said.

Technology to monitor harsh conditions in the deep ocean is critical for the expansion of offshore wind energy. Most wind energy is generated currently by turbines on land. Offshore wind is considered the next opportunity for growth. Harsh storms in the deep ocean, however, can be dangerous for offshore turbines, which are attached to the ocean floor with cables and have “floating” platforms that are not fixed to the sea floor.

A sensor that provides warnings about hazardous conditions in the deep sea could save lives by giving technicians time to reach safety, Jin said. The engineer also is developing sensors to protect the parts of offshore turbines above water, including the tower and blades, from wind damage.

Jin’s lab includes a sand blowing system with adjustable particle volume fractions and sand ejection speed. The setup allows researchers to study how sand blowing in the air affects turbine or rotorcraft blades. Earlier this year, Jin received a $360,000 Early Career Program Award from the U.S. Army Combat Capabilities Development Command Army Research Laboratory for a project to test the impact of sand on rotating blades.

“With wind turbines, you don’t want the blades to bend,” he said. “If winds are too strong, the tower could break down. The risks for offshore turbines are even greater.”

Jin said he joined UT Dallas in 2019 because of the University’s growing wind research programs through the Wind Energy Center, also called UTD Wind. Since then, he said he has seen an increase in students who want to prepare for careers in the wind energy industry.

“Clean energy has become one of the big topics around the world,” Jin said. “One of the biggest potential sources of clean energy comes from wind energy. In the future, there will be more focus on offshore wind production because it can generate more energy than turbines on land.”

 

About the Fellowship

The Early-Career Research Fellow program supports emerging scientific leaders as they take on untested research ideas, pursue unique collaborations, and build a network of colleagues who share their interest in advancing the safety of the offshore energy system and improving the well-being of coastal communities and ecosystems.