Tag Archives: hormone

New, wearable cortisol sensor can help warn us of incoming burnout or depression

It’s no secret that life can get rough. Those who have to contend with that for too long can start feeling overwhelmed — burned out by the stress. Now, a team of researchers proposes a new approach through which we can quantify how much stress someone is under, and for how long. They hope that the new wearable device can help prevent burnout, and let us know when someone is most in need of support or a good old fashioned break from the stress.

Image via Pixabay.

The new device was designed by a team of engineers at Ecole Polytechnique Fédérale de Lausanne (EPFL) Nanoelectronic Devices Laboratory (Nanolab) and Xsensio, a Swiss-based biotech company. It takes the shape of a wearable sensor that measures the levels of stress hormone cortisol in a person’s sweat. This figure can then be used to gauge the levels of cortisol in the blood.

The sensor is placed directly on the skin and provides continuous readings of this hormone’s levels in their sweat.

Skin-deep stress

“Cortisol can be secreted on impulse — you feel fine and suddenly something happens that puts you under stress, and your body starts producing more of the hormone,” says Adrian Ionescu, head of Nanolab.

“But in people who suffer from stress-related diseases, this circadian rhythm is completely thrown off. If the body makes too much or not enough cortisol, that can seriously damage an individual’s health, potentially leading to obesity, cardiovascular disease, depression or burnout.”

Cortisol is synthesized from cholesterol in our body’s adrenal glands — these sit right on top of your kidneys. How much of it is secreted is in turn controlled by the pituitary gland in our brains through the use of the adrenocorticotropic hormone (ACTH).

It’s easy to read “stress hormone” and immediately assume cortisol is a bad guy, but that’s simply not true. As we’ve seen previously, stress is a completely natural and deeply useful response; the issue with it today is that we’re feeling much more stress than we would in our natural environment. In other words, stress isn’t the issue — too much stress, is.

In our day-to-day, cortisol has some very important functions, including keeping our metabolism, blood sugar, and blood pressure in check. It’s also deeply involved in other cardiovascular functions and the workings of the immune system. In a stressful situation, be it something life-threatening or a simple annoyance, cortisol is flooded into the body to make us ready for our ‘fight or flight’. This mostly means prepping up our brain, muscles, and heart for intense activity and possible injury.

Still, cortisol levels in the blood ebb and flow naturally throughout the day, following our circadian rhythm, to keep us functional or asleep as needed. It generally peaks between 6 am and 8 am to rouse us from sleep and then decreases gradually.

Since cortisol is such a good marker for how stressed we feel and how stressed our body actually is, it’s often used as a gold standard to gauge stress. To do that however you need a blood sample, and those aren’t something you can take just anywhere throughout your day.

That’s why the team designed a wearable sensor to measure how much cortisol an individual excretes through their skin. It contains a transistor and a graphene electrode, which the authors explain has very high sensitivity and can detect even low levels of the hormone. Aptamers, short fragments of single-stranded DNA or RNA that can bind to specific compounds, are tied to this graphene electrode, allowing it to interact with the cortisol molecule. Since the aptamers used naturally contain a negative charge, they will be electrostatically attracted to the cortisol molecule and release a charge as they bind together.

The more such molecules are present, the stronger the overall charge becomes. This allows for an accurate and direct measurement of its levels in sweat. The authors explain that this is the first device intended to continuously monitor cortisol levels throughout the circadian cycle (i.e. throughout the day).

“That’s the key advantage and innovative feature of our device. Because it can be worn, scientists can collect quantitative, objective data on certain stress-related diseases. And they can do so in a non-invasive, precise and instantaneous manner over the full range of cortisol concentrations in human sweat,” adds Ionescu.

They tested the device in the lab and found it reliable and efficient; the next step is to now make it available for healthcare workers or researchers. They’ve set up a bridge project with Prof. Nelly Pitteloud, chief of endocrinology, diabetes, and metabolism at the Lausanne University Hospital (CHUV), where the device will be tested for continuous use in a real-life hospital setting. They intend to run the test using healthy individuals as well as patients with Cushing’s syndrome (who produce too much cortisol), Addison’s disease (too little cortisol), and stress-related obesity.

As far as the psychological ramifications of stress, the team explains that they are still “assessed based only on patients’ perceptions and states of mind, which are often subjective”. A system such as this patch can help us determine quite reliably how much cortisol is running through their system, which can be used to gauge those at risk of depression or burnout. If nothing else, it will help them support their claims with cold-hard figures.

The paper “Extended gate field-effect-transistor for sensing cortisol stress hormone” has been published in the journal Communications Materials.


The hunger hormone is involved in episodic memory in rats, new research finds

Ghrelin, the hormone that induces hunger, also seems to play a role in memory control.


Image credits Christine Sponchia.

If you’re sitting in a restaurant keenly anticipating a delicious meal that will be served shortly, chances are you’ll feel hungry. That sensation is created by ghrelin, a hormone secreted in the stomach as you anticipate food. Ghrelin has been linked with the mediation of hunger signals between our gut and our brain, but new research at the Society for the Study of Ingestive Behavior suggests that the molecule might also play an important part in memory control.

Food for memory

“We recently discovered that in addition to influencing the amount of food consumed during a meal, the vagus nerve also influences memory function,” said Dr. Scott Kanoski, senior author of the study.

After its secreted, ghrelin binds to specialized receptors on the vagus nerve, which transmits signals between the gut and the brain. The team’s hypothesis was that ghrelin might also help the vagus nerve support memory formation.

Using a method called RNA interference, the team artificially reduced the amount of ghrelin receptor in the vagus nerve for a group of lab rats. The animals were then put through a series of memory tasks. The rats with reduced ghrelin signaling in the vagus nerve showed impaired performance in an episodic memory test compared to the control group. Episodic memory is the type of memory involved in remembering what, when, and where something occurred. For the rats, the test required remembering a specific object in a specific location.

A second part of the study looked at whether ghrelin signaling in the vagal nerve influences feeding behavior. They report that mice whose vagus nerve can’t receive signals from ghrelin ate more frequently than unaltered mice but consumed less food at each meal. The team says this might come down to deficits in episodic memory associated with impaired ghrelin signaling rather than feelings of hunger.

“Deciding to eat or not to eat is influenced by the memory of the previous meal,” says Dr. Elizabeth Davis, lead author on the study. “Ghrelin signaling to the vagus nerve may be a shared molecular link between remembering a past meal and the hunger signals that are generated in anticipation of the next meal.”

The team plans to expand their research to see if they can improve memory capacity in humans by manipulating ghrelin signaling between the gut and the brain.

The findings, “Vagal afferent ghrelin signaling promotes episodic memory and influences meal patterns in rats” have been presented at the 2019 Annual Meeting of the Society for the Study of Ingestive Behavior in Utrecht, Netherlands, in July.

A lung-healing protein could be the reason why men recover from flu faster than women

In the United States, during the 1957 H2N2 pandemic, the number of deaths was higher among females than males. During the first and second wave of the 2009 H1N1 pandemic, a significant portion of patients hospitalized with severe 2009 H1N1 disease was comprised of young adult women. Data from the 2009 H1N1 pandemic, as well as from 2005, which was a bad year for seasonal influenza in Japan, reveal significant differences in morbidity rates between males and females. In 2010, the WHO published a report concluding that the outcome of pandemic influenza, as well as avian (bird flu) H5N1, is generally worse for young adult females.

pregnant woman

Credit: Public Domain

Pregnancy is an obvious female-specific risk factor associated with worse outcomes from seasonal and pandemic influenza infection, and likely contributes to the overall higher mortality in women compared to men. However, it does not appear to explain all of the differences between the sexes. Some researchers have postulated that the slower recovery by women from flu was linked to their greater levels of lung inflammation during flu infections. What else could be the reason?

According to a new study of mice and human cells, increased amounts of a lung-healing protein called amphiregulin (AREG) could be the reason why men recover from influenza more quickly than women. AREG, an Epidermal Growth Factor (EGF)-like molecule, has been shown to play a critical role in wound and tissue healing following infection or injury.

Vermillion, MS et al. Biology of Sex Differences 2018. 9:24

Scientists at Johns Hopkins Bloomberg School of Public Health, whose findings were published in the journal Biology of Sex Differences, infected live mice and human cells derived from male humans with a non-lethal dose of H1N1 — an Influenza A strain that caused over 18,500 laboratory-confirmed deaths worldwide in 2009 and 2010. Male and female mice had the same virus levels and cleared the virus in about the same amount of time.

Nevertheless, female mice had greater loss of body mass and more lung inflammation during the early phase of infection and were slower to return to normal lung function. Male mice genetically engineered to lack AREG had the same flu results as females. In a study of flu infections of mice and human lung epithelial cells in vitro, the investigators found significant increases in the production of AREG only when the cells were from males.

“The novel finding here is that females also have slower tissue-repair during recovery, due to relatively low production of amphiregulin,” study author Dr. Sabra Klein, an associate professor at Hopkins, said in a press release.

Scientists found that AREG, which has been known to promote the growth of epithelial cells in the skin, lung, and other surfaces in the body during wound healing, was the key factor, including during recovery from lung infections. Male mice produced significantly more AREG than females during the recovery phase of their infections.

It is not clear which factors drive the increased rise in AREG production in males during flu infection. Earlier in 2016, Professor Klein and colleagues showed that the sex hormone progesterone stimulates AREG production in female mice. They theorized that males evolved with greater wound-healing ability because they participated in more battles for territories, mates, and resources. The researchers initially thought the production of AREG increased in males during influenza infection because of testosterone. However, they found that the sex hormone, independently of AREG, does help protect male mice, which fared worse in flu infections without it.

Professor Klein’s group is now investigating the mechanisms of testosterone’s protective effect, as well as the factors that control AREG production during flu infection – a better understanding of these mechanisms could lead to new flu treatments that boost AREG production, particularly in women.

Eating out linked with hormonal disruptions, researchers say

A new study has discovered that eating out may increase exposure to harmful chemicals that are used to increase plastic’s flexibility and durability. Scientists believe that these chemical substances may cause hormonal imbalances.

Via Pixabay/StockSnap

Researchers have measured the blood levels of phthalates — binding agents frequently used in food packaging, adhesives, personal hygiene products, even flooring — and discovered that people who had eaten out in the previous day had 35% higher levels of phthalates than the participants who ate at home.

Recent studies associate phthalates with asthma, breast cancer, type 2 diabetes and fertility issues. Fortunately, the US has banned some of these nasty substances from children’s products.

According to the study, foods like burgers and sandwiches were at the top of the list when it came to high phthalate levels, but only if bought at a fast-food outlet, restaurant or cafe.

The research team observed that teenagers were the most affected age-group: teens who frequently consumed fast-food while out with their friends had 55% higher levels of the chemicals than young people who ate home-made food.

“This study suggests food prepared at home is less likely to contain high levels of phthalates, chemicals linked to fertility problems, pregnancy complications and other health issues. Our findings suggest that dining out may be an important, and previously under-recognised, source of exposure to phthalates for the US population,” said Researcher Dr Ami Zota, from George Washington University in Washington DC.

Researchers analyzed data from the US National Health and Nutrition Examination Survey (NHANES). A number of 10,253 participants provided information regarding what they ate and where their food came from over the past 24 hours. Next, scientists measured the phthalate levels found in each participant’s urine.

Participants reported that 61% of them ate out the previous day. Researchers demonstrated a significant association between phthalate exposure and dining out for all age groups, but concluded that young people showed the strongest one.

“Pregnant women, children and teens are more vulnerable to the toxic effects of hormone-disrupting chemicals, so it’s important to find ways to limit their exposures,” said lead author Dr Julia Varshavsky, from the University of California at Berkeley. “Future studies should investigate the most effective interventions to remove phthalates from the food supply,” she concluded.

The paper was published in the journal Environment International.

The story behind human growth hormone

Along the centuries, numerous explorers and scientists have searched for the fabled fountain of youth. Nowadays, most people don’t believe in magic fountains, but they’re striving for eternal youth through other ways — plastic surgeries, special diets, or hormones. Motivated by the “anti-aging” movement, people are placing their faith into all sorts of alleged cures, but does the science back things up?

Image credits: “Caveman Chuck” Coker

Hormones and short kids

As the Smithsonian eloquently puts it, genetically modified bacteria, brain-eating diseases, and short kids are all part of the history of human growth hormones (HGH) in the US. HGH is a peptide hormone that stimulates growth, cell reproduction, and cell regeneration in humans and other animals. It’s a tiny protein secreted by the pituitary gland, a pea-sized organ located near your brain, and sent to the bloodstream where it serves the functions mentioned above. Scientists have known about this hormone since the 1920s, but it wasn’t really used until the 1960s — mostly because acquiring it was so hard. The only source was humans, and gathering it from cadavers didn’t really seem like an attractive proposition.

However, conservatively, it started being administered to small children who weren’t growing properly and this went on for quite a while — until a grizzly discovery was made: one of the cadavers used for harvesting had been invested with Creutzfeldt-Jakob disease (CJD). CJD is similar in effects to mad cow disease or accelerated Alzheimer’s and quickly decays the brain. It can also lie dormant for decades. When researchers harvested the HGH, they also unknowingly harvested the virus and spread it. Some 26 people were killed and the life of everyone who was treated with HGH was turned upside down because the disease could manifest itself at any given time. It took a few years until researchers were able to develop another source of HGH, by using bacteria.

But people were extremely reluctant to use the hormone as the CJD panic was still fresh. Now, after about half a century, that care seems to have faded away and people are again looking into HGH.

Doping and aging

The pituitary gland sends out the hormone in short bursts, especially after exercise, trauma, and sleep. Generally, there’s more hormone secreted during the night than during the day. Research has also shown that production rises during childhood, peaks during puberty, and declines from middle age onward. It’s still used as a drug for children who suffer from an HGH deficiency (as well as some adults who suffer from this). Adults who are GH deficient get larger muscles, more energy, and improved exercise capacity from replacement therapy. They also experience increased stamina, protection from fractures, and a reduced risk of heart disease. But there’s a price to pay: Up to 30% of patients experience side effects that include fluid retention, joint and muscle pain, carpal tunnel syndrome, and high blood sugar levels.

HGH can be injected. Image credits: Psychonaught.

If you’ve ever done or followed sports, you probably see where this is going. Something that gives you bigger muscles and more energy, but is also risky? That’s doping. Indeed, HGH has been banned by the International Olympic Committee, Major League Baseball, the National Football League, and the World Anti-Doping Agency — among others. That hasn’t stopped it from tainting many sports… but there’s a strange kicker.

A team of researchers from California conducted a detailed review of 44 high-quality studies of growth hormone in athletes and found that while HGH does lead to an increase in muscle mass, that increase doesn’t really translate into better results. It gets even better: subjects who were given HGH were more likely to experience fatigue and retain fluid than those who were given the placebo. So while some still vouch for HGH as an (illegal) way of boosting sportive performance, that’s still a matter of debate.

Because HGH has been linked to protein production, the burning of fat, and sugar blood levels, some people thought “Hey, why not inject this and trick my body into thinking it’s young?” Indeed, “Every man desires to live long,” wrote Jonathan Swift, “but no man would be old.” According to Harvard, one estimate reported 20,000 to 30,000 Americans used GH as “anti-aging” therapy in 2004 alone; according to another, 100,000 people received GH without a valid prescription in 2002. This happens despite the fact that the FDA has not approved the use of GH for anti-aging, body building, or athletic enhancement. There is still an ongoing debate about the potential benefits of GHG in combating aging, but that’s questionable at best. Furthermore, a team of researchers which reviewed 31 high-quality studies that were completed after 1989 reports that while subjects gained an average of 4.6 pounds of lean body mass and shed a similar amount of body fat, they also reported side effects including fluid retention, joint pain, breast enlargement, and carpal tunnel syndrome. So again, there were positive responses, but for a price.

All in all, there is no universal cure, no fountain of youth. The best thing you can do is ensure a healthy lifestyle for yourself. Eat a balanced diet, work out, don’t stress too much. The basic things really do go a long way. If you do decide to go for something else, be sure you’re informed about what you’re doing.

How oxytocin and THC stimulate social interactions

A new study from the University of California looks at the link between the bonding hormone oxytocin and the effect of marijuana in social contexts that improve interpersonal bonding. Their findings offer insight into how the hormone could make social interactions more fulfilling and satisfying by enhancing our natural cannabinoid receptors.

The study, titled ”Endocannabinoid signaling mediates oxytocin-driven social reward” has been published in the journal PNAS.

The hormone Oxytocin.
Image via wikimedia

Oxytocin signals the brain to synthesize anandamide, dubbed the “bliss molecule,” as part of the reward mechanism in the brain — anandamide activates brain receptors that trigger feelings of happiness and motivation. It’s a naturally occurring molecule in the human body, but there’s another substance that links up with these receptors (the endocannabidoid system) with similar results: marijuana‘s THC.

Known as “the body’s own cannabinoid system,” the ECS is involved in a variety of physiological processes including appetite, pain-sensation, mood, memory, and mediates the psihoactive effects of cannabis in the brain. Previous studies have shown that the ECS has a part to play in the regulation of inter-neuron signalling in the nucleus accumbens, the region of the brain that oxytocin acts upon to reward social activities.

When the researchers stimulated the neurons responsible for anandamide production but blocked the effects of the molecule, they found that the effects of oxytocin on this area of the brain were also inhibited — suggesting that anandamide is the vector by which oxytocin strengthens social behavior in the brain.

To test this hypothesis, they administered drugs that prevent anandamide deterioration in mice, that showed increased enjoyment in social activities, spending much more time with other mice than the animals that were treated with a placebo. The team speculates that THC might also have a similar effect on the brain, promoting social interactions and heightening our enjoyment of such activities.

This is the first study to display the effect of oxytocin and marijuana-like neurotransmitters on humans  social interactions. The findings could help scientists delve into the functional mechanisms of oxytocin and allow them to better understand social-impairing conditions such as autism, and even help them develop new treatments to tackle the symptoms of autism.


Finger Length Ratios Indicate Sexual Orientation


In a meta-analysis study (a study that combines the results of many studies whose hypotheses are similar), researchers from the University of Ontario, Penn State, and the Centre for Addiction and Mental Health found that the second to fourth finger length ratio (2D:4D) serves as an indicator of sexual orientation.

“…lesbians had a smaller, more masculine 2D:4D than did heterosexual women, whereas gay and heterosexual men did not differ significantly in 2D:4D. The right-hand 2D:4D difference between lesbian and heterosexual women was estimated to be small to medium in size.This difference was robust,” the authors write.

But why might this ostensibly menial measurement correlate with such a multifarious and prominent aspect of the human psyche? And further, at the expense of coming off myopic, if this is true, why might have no one ever noticed this effect before? After all, who’s heard of the happily heterosexual female carpenter who after accidentally shortening either her second or fourth digit in a skill-saw accident suddenly turned lesbian? Or vice versa if she were one already.

In answering these questions, we’ve to remember that, “correlation is not causation.”– thus, while these findings certainly reveal a relationship between second and fourth finger length ratio and sexual orientation, they cannot, by definition, remark on the nature of the relationship. Take a breath: You can relax around Skill-saws again.

As to why these correlations exist, the researchers have penned androgen – steroids implemented in the regulation of male characteristics – as the culprit:

…our results support the hypothesis that prenatal androgen exposure affects sexual orientation in women. These results corroborate other evidence that androgen affects sexual orientation orientation, such as sexual attraction to males in persons with CAIS and sexual attraction to females in women with CAIS [Complete Androgen Insensitivity Syndrome] and prenatally normal males whose gender was reassigned near birth.

Other interesting findings of the study were: sampling location had an effect, where gay men had a lower ratio in Europe and a higher one in North America when compared to Heterosexual controls in both hands, but this effect was only observed in women in the left hand; and higher proportions of white homosexual subjects tended to have more masculine second to fourth finger length ratios.

If only one thing is to be contemplated and taken from this study, it should not be the results, but rather the means by which these results where obtained. Which is to say, quite blatantly, one should understand the nature of the mathematical processes that are utilized in compiling and analyzing such data. In this case we are reminded that, one, correlation is not causation: though two phenomena may be behave identically, so as to give the impression that one is causing the other, this is not necessarily the case; and two, in many instances when a correlation is observed there is often a third factor that is responsible for the observed other two, e.g., prenatal androgen having an effect on both 2D:4D and sexual orientation; and  lastly, while meta-analysis studies can be powerful, if the protocol by which a study is either included or omitted is compromised, so that a few studies that shouldn’t have been included are included or vice versa, the results may become eschewed. This is especially worrisome since the lead authors are relying on both their protocol and the research skills of many other researchers to obtain valid data.

Or more simply: finger length ratios don’t “cause” shifts in sexual orientation, but still, please be careful when handling your skill-saw.