GEMOLOGY

Groundbreaking study shows defects spreading through diamond faster than the speed of sound

Defects can make a material stronger or make it fail catastrophically; Knowing how fast they travel can help researchers understand things like earthquake ruptures, structural failures and precision manufacturing

Peer-Reviewed Publication

DOE/SLAC NATIONAL ACCELERATOR LABORATORY

 

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ILLUSTRATION OF AN INTENSE LASER PULSE HITTING A DIAMOND CRYSTAL FROM TOP RIGHT, DRIVING ELASTIC AND PLASTIC WAVES (CURVED LINES) THROUGH THE MATERIAL. THE LASER PULSE CREATES LINEAR DEFECTS, KNOWN AS DISLOCATIONS, AT THE POINTS WHERE IT HITS THE CRYSTAL. THEY PROPAGATE THROUGH THE MATERIAL FASTER THAN THE TRANSVERSE SPEED OF SOUND, LEAVING STACKING FACULTS – THE LINES FANNING OUT FROM THE IMPACT SITE – BEHIND. 

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CREDIT: GREG STEWART/SLAC NATIONAL ACCELERATOR LABORATORY

Settling a half century of debate, researchers have discovered that tiny linear defects can propagate through a material faster than sound waves do. 

These linear defects, or dislocations, are what give metals their strength and workability, but they can also make materials fail catastrophically ­– which is what happens every time you pop the pull tab on a can of soda. 

The fact that they can travel so fast gives scientists a new appreciation of the unusual types of damage they might do to a broad range of materials in extreme conditions ­­­­– from rock ripped apart by an earthquake rupture to aircraft shielding materials deformed by extreme stress, said Leora Dresselhaus-Marais, a professor at the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University who co-led the study with Professor Norimasa Ozaki at Osaka University. 

“Until now, no one has been able to directly measure how fast these dislocations spread through materials,” she said. Her team used X-ray radiography – similar to medical X-rays that reveal the inside of the body – to clock the speed of the propagating dislocations through diamond, yielding lessons that should apply to other materials, too. They described the results today in Science. 

Chasing the speed of sound 

Scientists have been debating whether dislocations can travel through materials faster than sound does for nearly 60 years. A number of studies concluded that they could not. But some computer models indicated that yes, they could – provided that they started out moving at faster-than-sound speed.

Getting them instantaneously up to this speed would require a tremendous shock. For one thing, sound travels a lot faster through solid materials than it does through air or water, depending on the nature and temperature of the material, among other factors. While the speed of sound through air is generally given as 761 mph, it’s 3,355 mph through water and an incredible 40,000 mph in diamond, the hardest material of all.

Complicating things even more, there are two types of sound waves in solids. Longitudinal waves are like the ones in air. But because solids put up some resistance to the passage of sound, they also host slower-moving waves known as transverse sound waves.

Knowing whether ultrafast dislocations can break either of these sound barriers is important from both the fundamental science and practical points of view. When dislocations move faster than sound speed, they behave quite differently and result in unexpected failures that have thus far only been modeled. Without measurements, no one knows how much damage those ultrafast dislocations can do. 

“If a structural material fails more catastrophically than anyone expected because of its high rate of failure, that’s not so good,” said Kento Katagiri, a postdoctoral scholar in the research group and first author of the paper. “If it’s a fault rupturing through rock during an earthquake, for instance, it could cause more damage to everything. We need to learn more about this type of catastrophic failure.” 

The results of this study, Dresselhaus-Marais added, “could suggest that what we thought we knew about the fastest possible materials failure was wrong.”

The pop-top effect 

To get the first direct images of how fast dislocations can travel, Dresselhaus-Marais and her colleagues performed experiments at the SACLA X-ray free-electron laser in Japan. They did the experiments on tiny crystals of synthetic diamond. 

Diamond offers a unique platform to study how crystalline materials fail, Katagiri said. For one thing, its deformation mechanism is simpler than those observed in metals, making it easier to interpret these challenging ultrafast X-ray imaging experiments. 

“To understand the damage mechanisms, we need to identify features in our images that are unambiguously dislocations, and not other types of defects,” he said. 

When two dislocations meet, they attract or repel each other and generate even more dislocations. Pop open a can of soda made from an aluminum alloy, and the many dislocations that are already in the lid – created when it was shaped into its final form – interact and spawn new dislocations by the trillions, which cascade into absolute critical failure as the top of the can flexes and the pop top snaps open. Those interactions and how they behave govern all the mechanical properties of materials we observe. 

“In diamond, there are only four types of dislocation, while iron, for instance, has 144 different possible types of dislocations,” Dresselhaus-Marais said.

Diamond may be much harder than metal, the researchers said. But much like a soda can, it will still bend by forming billions of dislocations if it’s shocked hard enough.  

Making X-ray images of shock waves 

At SACLA, the team used intense laser light to generate shock waves in diamond crystals. Then they essentially took a series of ultrafast X-ray images of the dislocations forming and spreading on a timescale of billionths of a second. Only X-ray free-electron lasers can provide X-ray pulses short enough and bright enough to capture this process. 

The initial shock wave split into two types of waves that continued to travel through the crystal. The first wave, called an elastic wave, temporarily deformed the crystal; its atoms bounced back into their original positions right away, like a rubber band that’s been stretched and released. The second wave, known as a plastic wave, permanently deformed the crystal by creating small errors in the repeating patterns of atoms that make up the crystal structure.

These tiny shifts, or dislocations, create “stacking faults” where adjacent layers of the crystal shift with respect to each other so they don’t line up the way they should. The stacking faults propagate outward from where the laser hit the diamond, and there is a moving dislocation at the leading tip of each stacking fault. 

With X-rays, the researchers discovered that the dislocations spread through diamond faster than the speed of the slower type of sound waves, the transverse waves ­– a phenomenon that had never been seen in any material before.

Now, Katagiri said, the team plans to go back to an X-ray free-electron facility, such as SACLA or SLAC’s Linac Coherent Light Source, LCLS, to see if dislocations can travel faster than the higher, longitudinal speed of sound in diamond, which will require even more powerful laser shocks. If and when they break that sound barrier, he said, they will be considered truly supersonic. 

Leora Dresselhaus-Marais is an investigator with the Stanford Institute for Materials and Sciences (SIMES) at SLAC and the Stanford PULSE Institute. Researchers from Osaka University, the Japan Synchrotron Radiation Research Institute, RIKEN SPring-8 Center and Nagoya University in Japan; DOE’s Lawrence Livermore National Laboratory; Culham Science Center in the UK; and École Polytechnique in France also contributed to this research. Major funding came from the U.S. Air Force Office of Scientific Research.

Citation: Kento Katagiri et al., Science, 6 October 2023 (10.1126/science.adh5563)

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How researchers got first direct images of defects spreading through material faster than the speed of sound 

DOE/SLAC NATIONAL ACCELERATOR LABORATORY

To get the first direct images of how fast dislocations can travel, researchers used an intense laser beam to drive shock waves through diamond crystals. Then they used an X-ray laser beam to make a series of X-ray images of the dislocations forming and spreading on a timescale of billionths of a second. The images, similar to medical X-rays that reveal the inside of the body, were recorded on a detector. 

CREDIT

K. Katagiri/Stanford University

How propagating dislocations leave stacking faults in a material 

DOE/SLAC NATIONAL ACCELERATOR LABORATORY

A shock wave traveling through a material can create defects known as dislocations – tiny shifts in the material’s crystal that propagate through it, leaving what are known as stacking faults behind. At left, the regular arrangement of the material’s atoms is undisturbed. At right, dislocations have traveled from left to right through the material, creating a stacking fault (purple) where adjacent layers of the crystal don’t line up quite the way they should.

CREDIT

Greg Stewart/SLAC National Accelerator Laboratory

This X-ray radiographic image ­– similar to a medical X-ray, but taken at ultrafast speed with an X-ray laser ­– shows shock waves traveling through a diamond crystal. The initial wave is elastic. The plastic wave follows, creating defects in the material called dislocations that propagate through the material faster than the speed of sound. The arrow shows the path and direction of one dislocation, which has left a linear defect called a stacking fault in its wake. The dislocation itself is seen at the tip of the arrow. Other stacking faults can be seen fanning out from the site of the laser shock. 

CREDIT

K. Katagiri/Stanford University

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JOURNAL

Science

DOI

10.1126/science.adh5563 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Transonic dislocation propagation in diamond

ARTICLE PUBLICATION DATE

5-Oct-2023

 

How to protect self-esteem when a career goal dies

Study shows the importance of how people view failures

Peer-Reviewed Publication

OHIO STATE UNIVERSITY

Many people fail at achieving their early career dreams. But a new study suggests that those failures don’t have to harm your self-esteem if you think about them in the right way.

Researchers found that people who viewed career goal failures as a steppingstone to new opportunities never lost self-esteem, no matter how many times they failed. But those who thought their failures left them worse off showed a drop-off in how they felt about themselves.

“It’s not how many times you have had to give up. It is how you felt about the failures, and whether you thought they led to something better for you,” said Patrick Carroll, lead author of the study and associate professor of psychology at The Ohio State University’s Lima campus.

Carroll conducted the research with Joshua McComis, a former student at Ohio State. The study was published recently in the Journal of Adult Development.

Many young people start off with ideas of what they want to be in the future, and those ideas of “possible selves” can be influenced by friends, family and teachers, among others, Carroll said.

For example, a young woman might embrace becoming a doctor in response to encouragement from a faculty adviser who says she is qualified to succeed in medicine.

But she could later abandon that dream because others felt she was not qualified, and decide to pursue psychology.

“It could be that she thinks this is a step down for her, and that she failed. That would harm her self-esteem,” he said.

“But she could also view psychology as more appropriate for her and a better fit, in which case her self-esteem would not suffer, despite the failure to become a doctor.”

The researchers conducted two studies.

In one study, 59 undergraduate students completed two surveys, one at the beginning of a semester and another at the end.  In the first survey, the students were asked, “How many times have you given up on a career goal?” No time frame was given.

They were then asked to rate the extent to which they regretted giving up on past career goals to pursue their present goal on a scale of 1 (definitely not) to 9 (definitely).

Participants completed a measure of their self-esteem that asked them to rate how much they agreed with statements like “I feel like I have a number of good qualities.”

All students rated their self-esteem again three months later at the end of the semester.

Results showed that students reported giving up on career goals between one and five times.

Overall, the study found that the more times students reported giving up on career goals, the more their self-esteem dropped over the semester. But when regret was factored in, those who showed low regret on changing career goals averaged little change in self-esteem, while those who had high regret did suffer from lowered self-esteem.

The second study involved 64 undergraduate students.  The study setup was similar, except the participants were also asked to rate the extent to which past revisions to their career goals ultimately led to a better career path.

“We found that when people felt their career goal failures led to something better, that takes away that hit to self-esteem,” Carroll said.

The findings suggest that people should approach failure in a way that can help them in the long run.

Although this is beyond the scope of this study, Carroll said there are techniques people can use to help make failure a way to learn and grow. For example, benefit finding is a way to find the good in a bad situation.

“We’re all going to have failures, some more than others.  But it is how you interpret those failures that matters in the long run in terms of how you feel about yourself,” he said.

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JOURNAL

Journal of Adult Development

DOI

10.1007/s10804-023-09461-8 

METHOD OF RESEARCH

Experimental study

SUBJECT OF RESEARCH

People

ARTICLE TITLE

The Consequences of Quality and Quantity of Downward Revisions in Possible Selves on Revisions in Core Selves

 

Grape consumption benefits eye health in human study of older adults

Grape intake improved macular pigment accumulation and downregulated harmful biomarkers

Peer-Reviewed Publication

CALIFORNIA TABLE GRAPE COMMISSION

In a recent randomized, controlled human study, consuming grapes for 16 weeks improved key markers of eye health in older adults.  The study, published in the scientific journal Food & Function looked at the impact of regular consumption of grapes on macular pigment accumulation and other biomarkers of eye health.[1]  This is the first human study on this subject, and the results reinforce earlier, preliminary studies where consuming grapes was found to protect retinal structure and function.[2]  

Science has shown that an aging population has a higher risk of eye disease and vision problems.  Key risk factors for eye disease include 1) oxidative stress and 2) high levels of ocular advanced glycation end products (AGEs).  AGEs may contribute to many eye diseases by damaging the vascular components of the retina, impairing cellular function, and causing oxidative stress.  Dietary antioxidants can decrease oxidative stress and inhibit the formation of AGEs, with possible beneficial effects on the retina, such as an improvement in Macular Pigment Optical Density (MPOD).  Grapes are a natural source of antioxidants and other polyphenols.

In this new study, 34 human subjects consumed either grapes (equivalent to 1 ½ cups of grapes per day) or a placebo for 16 weeks.  The grape eaters showed a significant increase in MPOD, plasma antioxidant capacity, and total phenolic content compared to those on placebo.  Those who didn’t consume grapes saw a significant increase in harmful AGEs, as measured in the skin.

“Our study is the first to show that grape consumption beneficially impacts eye health in humans which is very exciting, especially with a growing aging population,” said Dr. Jung Eun Kim.  “Grapes are an easy, accessible fruit that studies have shown can have a beneficial impact in normal amounts of just 1 ½ cups per day.” 

 

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[1] Hu, W., Zheng, R., Feng, Y., Tan, D., Chung-Tsing, G.C., Su, X., and Kim, J.E. (2023). Impacts of regular consumption of grapes on macular pigment accumulation in Singapore older adults: a randomized, controlled trial. Food Funct. 14, 8321-8330. Doi: 10.1039/d3fo02105j

[2] Patel, A.K., Davis, A., Rodriguez, M.E., Agron, S., Hackam, A.S. (2016). Protective effects of a grape-supplemented diet in a mouse model of retinal degeneration. Nutrition, 32, 384-390. Doi: 10.1016/j.nut.2015.09.017

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JOURNAL

Food & Function

DOI

10.1039/d3fo02105j 

METHOD OF RESEARCH

Randomized controlled/clinical trial

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Impacts of regular consumption of grapes on macular pigment accumulation in Singapore older adults: a randomized, controlled trial

 

Don’t feel appreciated by your partner? Relationship interventions can help

Peer-Reviewed Publication

UNIVERSITY OF ILLINOIS COLLEGE OF AGRICULTURAL, CONSUMER AND ENVIRONMENTAL SCIENCES

 

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ALLEN BARTON, UNIVERSITY OF ILLINOIS RESEARCHER, FOUND THAT FEELING APPRECIATED BY YOUR PARTNER IS IMPORTANT, AND GRATITUDE CAN BE INCREASED WITH RELATIONSHIP INTERVENTION PROGRAMS.

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CREDIT: FRED ZWICKY

When we’re married or in a long-term romantic relationship, we may eventually come to take each other for granted and forget to show appreciation. A new study from the University of Illinois Urbana-Champaign finds that it doesn’t have to stay this way.

The study examined why perceived gratitude from a spouse or romantic partner changes over time, and whether it can be improved through relationship intervention programs.

“Gratitude almost seems to be a secret sauce to relationships, and an important piece to the puzzle of romantic relationships that hasn’t gotten much attention in research studies until recently. And in couple relationships, it’s not just about being appreciative for your partner but also about feeling appreciated by your partner. Gratitude for couples is very interpersonal and something that is exchanged between partners,” said Allen Barton, assistant professor in the Department of Human Development and Family Studies, part of the  College of Agricultural, Consumer and Environmental Sciences (ACES) at U. of I. and an Illinois Extension specialist. Barton is lead author on the paper.

The study analyzed data from a randomized controlled trial with 615 low-income, help-seeking couples who signed up for an online relationship intervention program. Both partners had to participate in order to qualify for the study.

Couples assigned to the treatment group in the study participated in one of two online relationship education interventions, OurRelationship and ePREP, both of which provide couples with principles and practices to better communicate, understand conflict, and address problems in their relationship. Each program ran for 6 weeks and included online lessons and activities, as well as periodic meetings with a relationship coach.

A control group was assigned to a waitlist and did not receive intervention until after the study was completed. The researchers collected data through surveys before program participation began and at two-, four-, and six-month follow-ups.

Barton and his colleagues first looked at factors that predicted lower levels of perceived gratitude among the control group. They found that individuals who felt less appreciated by their partner were more likely to be female, married, and have children. Older age was also associated with a decline in perceived gratitude over time.

“These findings make sense. When we first meet somebody, we’re very mindful to show our appreciation. Over time, this tends to get lost, and people may not realize that neither partner feels as appreciated as they would like to be. From other research we have done, we know that ensuring partners feel acknowledged and valued will go a long way in promoting the quality of their relationship,” Barton stated.

The researchers also found that, for those assigned to the control group, perceived gratitude remained at the same level throughout the duration of the study despite improvements  in communication, satisfaction, and other relationship variables. Thus, while other aspects of the relationship may be more likely to fluctuate or increase, gratitude is not something that seems to improve by itself over time, Barton said.  

But can it get better with some outside assistance?

To answer that question, the authors examined whether perceived gratitude increased by participating in either of the two online relationship interventions.

Results indicated couples in the intervention group did, in fact, report improvement in partner gratitude relative to individuals in the control group. 

“We found that levels of perceived gratitude improved as a result of participating in these online relationship interventions, which have been shown to improve overall couple relationship quality across several dimensions. The effect on gratitude was not as large as program effects on some of the other aspects, which isn’t surprising because the program wasn’t focusing on gratitude, but there was still a measurable effect,” Baron explained.

Some relationship programs have been directed solely towards improving gratitude, but those have shown mixed results, Barton noted. When people express gratitude because they’ve been asked to do so as part of a program, it may come across as insincere and be less effective.

“Gratitude is a unique construct that seems to be lower in more established relationships, but it can be improved through efficacious relationship intervention programming. It has been an overlooked dimension that makes for healthy, supportive relationships. Our findings indicate we should develop programming that aims to improve levels of perceived gratitude, but it shouldn’t be the sole focus; it should be one component of the intervention,” he said.

Barton’s advice to couples is to be mindful of the power of saying “thank you.”

“If you’re married or in a romantic relationship, as simple as it may seem, make sure to regularly give specific, sincere compliments to your spouse or romantic partner. I also encourage couples to ask each other if there are areas where one person doesn’t feel appreciated and then work to remedy that,” he said.

“It takes a lot of work to make a family happen, and that work becomes all the more challenging when your efforts aren't acknowledged. So just ensuring there’s a regular rhythm in a relationship where both partners are expressing appreciation and both partners feel valued is important.”

The study focused on low-income couples, who were at or below 200% of the federal poverty line for a family.

“Financial strain can be a stressor for couples, and lower-income individuals tend to have higher relationship instability,” Barton noted. “Decades of social science research indicate that having strong marriages and couple relationships matters for individuals, for children, and for communities. A lot of factors influencing couple relationships are difficult to change but this–feeling appreciated by your partner–is one important factor that, as we show in this study, can be changed by effective interventions.”

Couples seeking help with their relationship can participate in the Strong Couples Project that is currently disseminating the ePREP program tested in this study. This project, offered through Illinois Extension and directed by Barton, is available free of charge to qualifying participants nationwide.

Editor's notes:

The paper, “Trajectories of perceived gratitude and change following relationship interventions: A randomized controlled trial with lower-income, help-seeking couples,” is published in Behavior Therapy [DOI: 10.1016/j.beth.2023.07.014]. Authors include Allen W. Barton, Qiujie Gong, Shayna Guttman, and Brian D. Doss.

This research was supported by Grant 90FM0063 from the U.S. Department of Health and Human Services Administration for Children and Families (ACF) awarded to Brian Doss.

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JOURNAL

Behavior Therapy

DOI

10.1016/j.beth.2023.07.014 

METHOD OF RESEARCH

Randomized controlled/clinical trial

SUBJECT OF RESEARCH

People

ARTICLE TITLE

Trajectories of perceived gratitude and change following relationship interventions: A randomized controlled trial with lower-income, help-seeking couples

 

New study at the Alzheimer’s Center at Temple casts light on protein that could help defeat Alzheimer’s disease and increase productive lifespan

Peer-Reviewed Publication

TEMPLE UNIVERSITY HEALTH SYSTEM

Alzheimer’s disease is the most common type of dementia, a disorder of progressively worsening memory and other thinking abilities. It rose up in the ranks of leading causes of death over the past several decades. It can also limit the duration of a working career, create uncertainty in the financial planning for retirement and rob patients of enjoyment and happiness in the final years. An effective treatment against this disease could give back to the patient the decision when to retire and improve quality of life in advanced age.  

Now, scientists at the Alzheimer’s Center at Temple at the Lewis Katz School of Medicine at Temple University are on the trail of a promising new therapeutic target – ABCA7, a protein known to protect from Alzheimer’s disease. The study, published online in the journal Cells, uncovers new information about the relationship between ABCA7, cholesterol, and inflammation in human brain cells.

The importance of ABCA7 in the development of Alzheimer’s disease first emerged in genome-wide association studies, which are large investigations of the human genome that involve thousands of participants. “But genome studies only point to a protein and do not tell us anything about how it functions or how it affects a disease,” said Joel Wiener, an investigator with the Alzheimer’s Center at Temple and first author on the new report. “Our goal is to reveal ABCA7’s functions and to use what we learn about its role in pathology to turn it into an effective therapy against Alzheimer’s disease.” 

Previous work led by Nicholas Lyssenko, Ph.D., an investigator at the Alzheimer’s Center at Temple and corresponding author on the new study, suggested that individuals between ages 63 and 78 who have low ABCA7 protein levels in the brain are at a greater risk of developing Alzheimer’s disease. This finding corroborated the conclusions of earlier genome studies and further indicated that the protein protects the human brain.

In the new study, Dr. Lyssenko’s team addressed how cholesterol metabolism and inflammation may manipulate ABCA7 levels in human brain cells and thus affect Alzheimer’s disease pathogenesis. In one set of experiments, the researchers depleted cholesterol in different neural cell lines, such as microglia, astrocytes and neurons, and then treated the cells with rosuvastatin, a medication that suppresses cholesterol synthesis. To determine the effect of inflammation on ABCA7, the team carried out another set of experiments in which the same cell lines were treated with one of three major proinflammatory cytokines: IL-1β, IL-6, or TNFα. Cytokines are small molecules that can trigger inflammation following their secretion from certain types of immune cells. 

The researchers found that ABCA7 levels dropped by about 40 percent in microglia cell lines and about 20 percent in an astrocyte cell line after the cells were depleted of more than half their usual amount of cholesterol. Meanwhile, no changes were observed in ABCA7 levels in a neuronal cell line following cholesterol loss. In addition, IL-1β and TNFα suppressed ABCA7 expression only in microglial cells. The third cytokine, IL-6, had no impact on ABCA7 in microglia, and none of the three cytokines induced changes in ABCA7 levels in either astrocytes or neurons.

These observations advance understanding of how ABCA7 is regulated in the brain. “Our findings suggest that cholesterol loss downregulates ABCA7 in many cells in the human brain. Previous work in mice showed that cholesterol loss upregulates ABCA7,” said Mr. Wiener. “In addition, other investigators found that inflammation suppresses ABCA7 in astrocytes, and we show now that this can also happen in microglia. Overall, cholesterol depletion and inflammation may reduce ABCA7 levels in the brain and cause the onset of Alzheimer’s disease.”

The Temple team is taking multiple approaches to studying ABCA7, using not only human cells but also carrying out experiments in animal models and in postmortem human brain tissue. “The greatest challenge now is to figure out how to measure ABCA7 levels in the brain of living humans,” Dr. Lyssenko added. “If we achieve this, we could verify whether inflammation suppresses ABCA7 in the human body. Effective testing for ABCA7 levels in the brain will also identify individuals who are at greater risk for Alzheimer’s disease and spur the development of new ABCA7-based therapies.”  

Other researchers who contributed to the study include Sindy Desire, Viktor Garliyev, Nicholas Lyssenko III, and Domenico Praticò, Alzheimer's Center at Temple, Department of Neural Sciences, Lewis Katz School of Medicine.

The research was supported by funding from the National Institute on Aging at the National Institutes of Health (NIH) and from the Pennsylvania Department of Health, Commonwealth Universal Research Enhancement Program.

About the Lewis Katz School of Medicine

Founded in 1901, the Lewis Katz School of Medicine at Temple University attracts students and faculty committed to advancing individual and population health through culturally competent patient care, research, education, and service. The School confers the MD degree; MS and PhD degrees in Biomedical Science; the MA in Urban Bioethics; the MS in Physician Assistant studies; a certificate in Narrative Medicine; a non-degree post-baccalaureate program; several dual degree programs with other Temple University schools; continuing medical education programs; and in partnership with Temple University Hospital, 40 residency and fellowship programs for physicians. The School also manages a robust portfolio of publicly and privately funded transdisciplinary studies aimed at advancing the prevention, diagnosis, and treatment of disease -- with specialized research centers focused on heart disease, cancer, substance use disorder, metabolic disease, and other regional and national health priorities. To learn more about the Lewis Katz School of Medicine, please visit: medicine.temple.edu.

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JOURNAL

Cells

DOI

10.3390/cells12172143 

ARTICLE TITLE

Down-Regulation of ABCA7 in Human Microglia, Astrocyte and THP-1 Cell Lines by Cholesterol Depletion, IL-1β and TNFα, or PMA

 

Evidence on increased rates of diabetes unclear in trans people, but evidence on higher rates of cardiovascular disease clear

Testosterone therapy thought to be partly behind the increased risk in trans men

Reports and Proceedings

DIABETOLOGIA

The latest data on the metabolic problems faced by trans people are presented at a session at this year’s Annual Meeting of the European Association for the Study of Diabetes (Hamburg 2-6 October). While evidence on increased or decreased rates of diabetes among trans men and women remains unclear, the evidence that they face higher rates of cardiovascular disease continues to mount. The talk is by Dr Dorte Glintborg, Department of Endocrinology, Odense University Hospital, Denmark.

“While increased rates of cardiovascular disease might normally go hand-in-hand with increased rates of diabetes, for trans men (assigned female at birth AFAB), use of testosterone usually increases lean body mass and this could be protecting against an increased risk of diabetes,” explains Dr Glintborg.

“For transwomen (assigned male at birth, AMAB), hormone treatments such as oestrogen will increase fat mass and lower lean body mass, and increased oestrogen is usually associated with increased risk of autoimmune disease and inflammation. Some studies found a higher risk of type 2 diabetes in transgender women, but this could not be confirmed by others.”

She adds: “Several other factors apart from body fat/leanness and muscle mass could affect risk of vascular and metabolic diseases in transgender populations and we still need more long-term data. Indeed, it has been discussed that mental support as part of transgender care could relieve minority stress and could be protective against development of cardiovascular disease. Lifestyle changes during hormone treatment and especially higher physical activity in transgender men could protect against T2D.”

However, Dr Glintborg explains the field is still rapidly evolving and “we lack large study cohorts”.

Dr Glintborg will discuss various studies on the elevated cardiovascular risk faced by the transgender population, including one by herself and colleagues, published in The European Journal of Endocrinology, which showed that, compared with cis-gender individuals, transgender men and women were at increased risk of cardiovascular disease. The main outcome measure was cardiovascular diagnosis (any CVD) including medicine prescriptions for CVD during 2000–2018.

The authors used Danish health registers to determine cardiovascular outcomes (ICD-10 codes) and medicine prescriptions regarding CVD medicine. The Danish transgender cohort (N= 2671) included persons with International Classification of Diseases-10 diagnosis code of ‘gender identity disorder’ (1583), which implied contact to a Danish centre of gender identity and persons who had had a legal sex change (n = 1088), which implied that they had contacted the legal system and changed their gender. In total, the transgender study cohort included 1270 persons who were assigned female at birth (AFAB, transgender men) and 1401 were assigned male at birth (AMAB, transgender women).

The control population (N= 26 710) were matched to the transgender population by age (n = 5 controls of same and n = 5 controls of other birth sex) of the respective transgender case. The cohort was young - median age at study inclusion was 22 years for AFAB and 26 years for AMAB. By definition younger people generally have much lower rates of CV disease, but in this study hypertension (high blood pressure) and dyslipidaemia (abnormal blood fats) were the most common problems and could usually be treated a visit to the person’s general practitioner and receiving a prescription.

The mean follow-up time was 4.5 years for AFAB and 5.7 years for AMAB. The increased risk of any CVD was significantly higher in both transgender men and women as compared with control men or women. Transgender males (AFAB) had a 2.2 times increased risk of CVD compared with control men and a 63% increased risk compared with control women.  Transgender females (AMAB) had a 93% increased risk of any CVD versus control men, and a 73% increased risk compared with control women. 

Analysis of the use of gender-affirming hormone treatment (GAHT) suggested around a third of the increased risk for CVD outcomes in transgender males could be attributed to GAHT – previous research has also associated the use of hormones such as testosterone with increased cardiovascular risk. Yet in transgender females, use of GAHT (oestrogen in combination with testosterone blocker), could not explain increased CVD risk.

The authors highlight that this register-based data study did not allow them to investigate the influence of BMI, family history of CVD, minority stress and lifestyle factors (diet, smoking, exercise) on study outcomes. From this study, they concluded: “Cardiovascular and metabolic outcomes were more prevalent in transgender persons compared to controls. Gender-affirming hormone therapy exposure could contribute to the elevated cardiovascular risk in transgender men, assigned female at birth. Future studies will be able to bring further knowledge regarding mechanisms for higher cardiovascular risk in transgender men and women.”

Dr Glintborg adds: “We need no determine more about the mechanisms for adverse metabolic outcomes – are they mediated by changes in body composition or other mechanisms such as stress and lifestyle changes? For example, in many countries you need to lose weight (in Denmark to a body mass index of below 27) to become eligible for gender affirming surgery and you have to stop smoking. This could be protective against adverse outcomes.”

“A more detailed evaluation of fat, muscle, and liver function and could all be very valuable regarding mechanisms for changes in metabolic function. And randomised controlled trials regarding different treatment regiments would help massively in increasing our understanding of metabolic changes.”

And another important element affecting transgender care is the huge increase in demand for services in most European / Western countries. The resulting delay in patients receiving their first and subsequent appointments is leading to more trans women self-medicating with cyproterone acetate to supress the side effects of hormone (testosterone) therapy. Cyproterone acetate is a synthetic progestin and some studies found higher risk of hypertension in transwomen using the drug. “We need to investigate if use of cyproterone acetate in Europe is a risk factor for CVD in transgender women,” explains Dr Glintborg.

In fact, many different medication regimens are used throughout the transition journeys of trans men and trans women, and Dr Glintborg would like to see as many combinations as possible investigated for their effects on the health of transgender people.

Dr Glintborg will also discuss the idea that “the benefits of GAHT on mental health could outbalance negative effects on cardiovascular markers caused by being part of this minority group – or so-called ‘minority stress’. Like all patients with metabolic issues, doctors should discuss with their transgender patients the important of physical activity, avoiding weight gain, and stopping or avoiding starting smoking”.
 

 

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ARTICLE PUBLICATION DATE

5-Oct-2023

 

Natural GM crops: grasses take evolutionary shortcut by borrowing genes from their neighbours

Peer-Reviewed Publication

UNIVERSITY OF SHEFFIELD

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• New study shows grasses are taking an evolutionary shortcut by continually borrowing genes from their neighbours to grow bigger, stronger and taller
• The research, led by the University of Sheffield, is the first to show how frequently grasses exchange genes in the wild
• The naturally occurring process observed in grasses, including in some of the crops we eat, may mirror methods used to make genetically modified crops
• Understanding the rate is important to know the potential impact it can have on a plant’s evolution and how it can drive adaption to the environment

Grass may transfer genes from their neighbours in the same way genetically modified crops are made, a new study has revealed. 

Research, led by the University of Sheffield, is the first to show the frequency at which grasses incorporate DNA from other species into their genomes through a process known as lateral gene transfer.

The stolen genetic secrets give them an evolutionary advantage by allowing them to grow faster, bigger or stronger and adapt to new environments quicker. 

Understanding the rate is important to know the potential impact it can have on a plant’s evolution and how it adapts to the environment. 

Grasses are the most ecologically and economically important group of plants, covering 30% of the earth's terrestrial surface and producing a majority of our food.  

The Sheffield team sequenced multiple genomes of a species of tropical grass and determined at different time points in its evolution how many genes were acquired - giving a rate of accumulation. 

It is now thought these transfers are likely to occur in the same way that some genetically modified crops are made. 

These findings, published in the journal New Phytologist could inform future work to harness the process to improve crop productivity and make more resilient crops, and have implications on how we view and use controversial GM crops.

Dr. Luke Dunning, Research Fellow from the University of Sheffield’s School of Biosciences, and senior author of the research, said: “There are many methods to make GM crops, some which require substantial human intervention and some that don’t. Some of these methods that require minimal human intervention could occur naturally and facilitate the transfers we have observed in wild grasses.

“These methods work by contaminating the reproductive process with DNA from a third individual. Our current working hypothesis, and something we plan to test in the near future, is that these same methods are responsible for the gene transfers we document in wild grasses.

“This means, in the near future, controversial genetic modification could be perceived as more of a natural process.

“Currently, these ‘natural’ reproductive contamination methods are not as efficient in producing GM plants as those that are used routinely, but by further understanding how lateral gene transfer occurs in the wild we may be able to increase the success of this process.”

Since Darwin, much of our understanding of evolution has been based on the assumption that genetic information is passed from parents to offspring - the rule of common descent for plant and animal evolution. 

The team's next steps will be to verify their hypothesis by recreating known examples of lateral gene transfer, to investigate whether this ongoing process contributes to the differences we observe between crop varieties.

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JOURNAL

New Phytologist

METHOD OF RESEARCH

Observational study

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

Lateral gene transfer generates accessory genes that accumulate at different rates within a grass lineage

ARTICLE PUBLICATION DATE

5-Oct-2023