Tag Archives: smell

Evidence that babies react to taste, smell in the womb; Carrot for “laughter-face” response, kale for “cry-face” response: Study

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A study led by Durham University’s Fetal and Neonatal Research Lab, UK, took 4D ultrasound scans of 100 pregnant women to see how their unborn babies responded after being exposed to flavours from foods eaten by their mothers.

Researchers looked at how the fetuses reacted to either carrot or kale flavours just a short time after the flavours had been ingested by the mothers.

Fetuses exposed to carrot showed more “laughter-face” responses while those exposed to kale showed more “cry-face” responses.

Their findings could further our understanding of the development of human taste and smell receptors.

The researchers also believe that what pregnant women eat might influence babies’ taste preferences after birth and potentially have implications for establishing healthy eating habits.

The study is published in the journal Psychological Science.

pregnant lady

pregnant lady/Commons.wikimedia.org

Humans experience flavour through a combination of taste and smell. In fetuses it is thought that this might happen through inhaling and swallowing the amniotic fluid in the womb.

Lead researcher Beyza Ustun, a postgraduate researcher in the Fetal and Neonatal Research Lab, Department of Psychology, Durham University, said: “A number of studies have suggested that babies can taste and smell in the womb, but they are based on post-birth outcomes while our study is the first to see these reactions prior to birth.

“As a result, we think that this repeated exposure to flavours before birth could help to establish food preferences post-birth, which could be important when thinking about messaging around healthy eating and the potential for avoiding ‘food-fussiness’ when weaning.

“It was really amazing to see unborn babies’ reaction to kale or carrot flavours during the scans and share those moments with their parents.”

The research team, which also included scientists from Aston University, Birmingham, UK, and the National Centre for Scientific Research-University of Burgundy, France, scanned the mothers, aged 18 to 40, at both 32 weeks and 36 weeks of pregnancy to see fetal facial reactions to the kale and carrot flavours.

Mothers were given a single capsule containing approximately 400mg of carrot or 400mg kale powder around 20 minutes before each scan. They were asked not to consume any food or flavoured drinks one hour before their scans.

A 4D scan image of a fetus showing a neutral face/CREDIT: FETAP (Fetal Taste Preferences) Study, Fetal and Neonatal Research Lab, Durham University.

The mothers also did not eat or drink anything containing carrot or kale on the day of their scans to control for factors that could affect fetal reactions.

Facial reactions seen in both flavour groups, compared with fetuses in a control group who were not exposed to either flavour, showed that exposure to just a small amount of carrot or kale flavour was enough to stimulate a reaction.

Co-author Professor Nadja Reissland, head of the Fetal and Neonatal Research Lab, Department of Psychology, Durham University, supervised Beyza Ustun’s research. She said: “Previous research conducted in my lab has suggested that 4D ultrasound scans are a way of monitoring fetal reactions to understand how they respond to maternal health behaviours such as smoking, and their mental health including stress, depression, and anxiety.

“This latest study could have important implications for understanding the earliest evidence for fetal abilities to sense and discriminate different flavours and smells from the foods ingested by their mothers.”

Co-author Professor Benoist Schaal, of the National Centre for Scientific Research-University of Burgundy, France, said: “Looking at fetuses’ facial reactions we can assume that a range of chemical stimuli pass through maternal diet into the fetal environment.

“This could have important implications for our understanding of the development of our taste and smell receptors, and related perception and memory.”

The researchers say their findings might also help with information given to mothers about the importance of taste and healthy diets during pregnancy.

They have now begun a follow-up study with the same babies post-birth to see if the influence of flavours they experienced in the womb affects their acceptance of different foods.

Research co-author Professor Jackie Blissett, of Aston University, said: “It could be argued that repeated prenatal flavour exposures may lead to preferences for those flavours experienced postnatally. In other words, exposing the fetus to less ‘liked’ flavours, such as kale, might mean they get used to those flavours in utero.

“The next step is to examine whether fetuses show less ‘negative’ responses to these flavours over time, resulting in greater acceptance of those flavours when babies first taste them outside of the womb.”

Related: http://dx.doi.org/10.1177/09567976221105460

 

Scent, sweat from human skin attract disease-spreading mosquitoes

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Mosquitoes that spread Zika, dengue and yellow fever are guided toward their victims by a scent from human skin. The exact composition of that scent has not been identified until now.

A UC Riverside-led team discovered that the combination of carbon dioxide plus two chemicals, 2-ketoglutaric and lactic acids, elicits a scent that causes a mosquito to locate and land on its victim. This chemical cocktail also encourages probing, the use of piercing mouthparts to find blood.

This chemical mixture appears to specifically attract female Aedes aegypti mosquitoes, vectors of Zika as well as chikungunya, dengue, and yellow fever viruses. This mosquito originated in Africa, but has spread to tropical and subtropical regions worldwide, including the U.S.

Mosquitoes use a variety of cues to locate their victims, including carbon dioxide, sight, temperature, and humidity. However, Cardé’s recent research shows skin odors are even more important for pinpointing a biting site.

Aedes aegyptii mosquito biting a person./CREDIT CDC

“We demonstrated that mosquitoes land on visually indistinct targets imbued with these two odors, and these targets aren’t associated with heat or moisture,” Cardé said. “That leaves skin odor as the key guiding factor.”

Given the significance of odor in helping mosquitoes successfully feed on humans, Cardé wanted to discover the exact chemicals that make our scent so potent for the insects. Part of the equation, lactic acid, was identified as one chemical element in the odor cocktail as long ago as 1968.

Since then, several studies have identified that carbon dioxide combined with ammonia, and other chemicals produced by humans also attract these mosquitoes. However, Cardé, who has studied mosquitoes for 26 years, felt these other chemicals were not strong attractants.

Methods that chemists typically use to identify these chemicals would not have worked for 2-ketoglutaric acid, Cardé said. Gas chromatography, which separates chemicals by their molecular weight and polarity, would have missed this acid.

“I think that these chemicals may not have been found before because of the complexity of the human odor profile and the minute amounts of these compounds present in sweat,” said chemist Jan Bello, formerly of UCR and now with insect pest control company Provivi.

Searching for mosquito attractors, Cardé turned to Bello, who extracted compounds from the sweat in his own feet. He filled his socks with glass beads and walked around with the beads in his socks for four hours per odor collection.

Credit: MINDY TAKAMIYA/KYOTO UNIVERSITY ICEMS

“Wearing the beads felt almost like a massage, like squeezing stress balls full of sand, but with your feet,” said Bello. ‘The most frustrating part of doing it for a long time is that they would get stuck in between your toes, so it would be uncomfortable after a while.”

The inconvenience was worth the investment. Bello isolated chemicals from the sweat deposited on the sock beads and observed the mosquitoes’ response to those chemicals. In this way, the most active combination emerged.

Future studies are planned to determine whether the same compound is effective for any other mosquitoes, and why there is such variation in how individuals are apt to be bitten. “Some are more attractive than others to these mosquitoes, but no one’s yet established why this is so,” Cardé said.

Though this discovery may not lead to insights for the development of new repellants, the research team is hopeful their discovery can be used to attract, trap, and potentially kill disease-spreading mosquitoes.

Nasal irrigation twice a day reduces COVID-related illness, death

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Starting twice daily flushing of the mucus-lined nasal cavity with a mild saline solution soon after testing positive for COVID-19 can significantly reduce hospitalization and death, investigators report.

They say the technique that can be used at home by mixing a half teaspoon each of salt and baking soda in a cup of boiled or distilled water then putting it into a sinus rinse bottle is a safe, effective and inexpensive way to reduce the risk of severe illness and death from coronavirus infection that could have a vital public health impact.

“What we say in the emergency room and surgery is the solution to pollution is dilution,” says Dr. Amy Baxter, emergency medicine physician at the Medical College of Georgia at Augusta University

“By giving extra hydration to your sinuses, it makes them function better.

If you have a contaminant, the more you flush it out, the better you are able to get rid of dirt, viruses and anything else,” says Baxter.

“We found an 8.5-fold reduction in hospitalizations and no fatalities compared to our controls,” says senior author Dr. Richard Schwartz, chair of the MCG Department of Emergency Medicine. “Both of those are pretty significant endpoints.”

Drs. Richard Schwartz and Amy Baxter/Photo:Medical College of Georgia

The study appears to be the largest, prospective clinical trial of its kind and the older, high-risk population they studied — many of whom had preexisting conditions like obesity and hypertension — may benefit most from the easy, inexpensive practice, the investigators say.

They found that less than 1.3% of the 79 study subjects age 55 and older who enrolled within 24-hours of testing positive for COVID-19 between Sept. 24 and Dec. 21, 2020, experienced hospitalization. No one died.

Among the participants, who were treated at MCG and the AU Health System and followed for 28 days, one participant was admitted to the hospital and another went to the emergency room but was not admitted.

Schwartz says Baxter brought him the idea early in the pandemic and he liked that it was inexpensive, easy to use and could potentially impact millions at a time where, like other health care facilities, the Emergency Department of the AU Health System was starting to see a lot of SARS-CoV-2-positive patients.

They knew that the more virus that was present in your body, the worse the impact, Baxter says. “One of our thoughts was: If we can rinse out some of the virus within 24 hours of them testing positive, then maybe we can lower the severity of that whole trajectory,” she says, including reducing the likelihood the virus could get into the lungs, where it was doing permanent, often lethal damage to many.

Covid/commons.wikimedia.org

Additionally, the now-infamous spiky SARS-CoV-2 is known to attach to the ACE2 receptor, which is pervasive throughout the body and in abundance in locations like the nasal cavity, mouth and lungs. Drugs that interfere with the virus’ ability to attach to ACE2 have been pursued, and Baxter says the nasal irrigation with saline helps decrease the usual robust attachment. Saline appears to inhibit the virus’ ability to essentially make two cuts in itself, called furin cleavage, so it can better fit into an ACE2 receptor once it spots one.

Participants self-administered nasal irrigation using either povidone-iodine, that brown antiseptic that gets painted on your body before surgery, or sodium bicarbonate, or baking soda, which is often used as a cleanser, mixed with water that had the same salt concentration normally found in the body.

But their experience indicates the saline solution alone sufficed. “It’s really just the rinsing and the quantity that matter,” Baxter says.

The investigators also wanted to know any impact on symptom severity, like chills and loss of taste and smell. Twenty-three of the 29 participants who consistently irrigated twice daily had zero or one symptom at the end of two weeks compared to 14 of the 33 who were less diligent.

Those who completed nasal irrigation twice daily reported quicker resolution of symptoms regardless of which of two common antiseptics they were adding to the saline water.

Others have shown the nasal irrigation, also called lavage, can also be effective in reducing duration and severity of infection by a family of viruses that include the coronaviruses, which are also known to cause the common cold, as well as the influenza viruses, the investigators write. “SARS-CoV-2 infection was another perfect situation for it,” Baxter says.

In fact, nasal irrigation is something that has been done for millennia in Southeast Asia, and Baxter had noted lower death rates from COVID-19 in countries like Laos, Vietnam and Thailand. “Those were places that I knew from having been there where they use nasal irrigation as a normal part of hygiene just like brushing their teeth,” she says. A 2019 pre-COVID study provided evidence that regular nasal irrigation in Thailand can improve nasal congestion, decrease postnasal drip, improve sinus pain or headache, improve taste and smell and improve sleep quality.

Saline water

Schwartz said the simplicity and safety of the treatment had him recommending nasal irrigation to positive patients early on and the published results make him even more confident in recommending nasal irrigation to essentially anyone who tests positive.

“Many of the people who have been using this now for months have told me their seasonal allergies have gone away, that it really makes a huge difference in any of the things that go through the nose that are annoying.”

A study released in September 2020 indicated that gargling with a saline-based solution can reduce viral load in COVID-19, and another released in 2021 suggested that saline works multiple ways to reduce cold symptoms related to infection with other coronaviruses and might work as well as a first-line intervention for COVID-19.

Despite the two nostrils, the nasal sinus is just one cavity, so the water is pushed into one side and comes out the other, Baxter notes.

Now using machine learning, find out odors and fragrances

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Tokyo Institute of Technology researchers have invented a new method that predicts smell based on  the odor impression instead of predicting the smell from molecular features.

As the sense of smell is one of the basic senses of animal species, it is critical to finding food, realizing attraction, and sensing danger. Humans detect smells, or odorants, with olfactory receptors expressed in olfactory nerve cells.

These olfactory impressions of odorants on nerve cells are associated with their molecular features and physicochemical properties. This makes it possible to tailor odors to create an intended odor impression. Current methods only predict olfactory impressions from the physicochemical features of odorants. But, that method cannot predict the sensing data, which is indispensable for creating smells.

To tackle this issue, scientists from Tokyo Institute of Technology (Tokyo Tech) have employed the innovative strategy of solving the inverse problem. Instead of predicting the smell from molecular data, this method predicts molecular features based on the odor impression.

Using standard mass spectrum data and machine learning (ML) models, the Tokyo Tech team has found a new method. “We used a machine-learning-based odor predictive model that we had previously developed to obtain the odor impression. Then we predicted the mass spectrum from odor impression inversely based on the previously developed forward model,” explains Professor Takamichi Nakamoto, the leader of the research effort by Tokyo Tech. The findings have been published in PLoS One.

Aroma/Photo:en.wikipedia.org

This simple method allows for the quick preparation of the predicted spectra of odor mixtures and can also predict the required mixing ratio, an important part of the recipe for new odor preparation.

“For example, we show which molecules give the mass spectrum of apple flavor with enhanced ‘fruit’ and ‘sweet’ impressions. Our analysis method shows that combinations of either 59 or 60 molecules give the same mass spectrum as the one obtained from the specified odor impression. With this information, and the correct mixing ratio needed for a certain impression, we could theoretically prepare the desired scent,” highlights Prof. Nakamoto.

This novel method can provide highly accurate predictions of the physicochemical properties of odor mixtures, as well as the mixing ratios required to prepare them, thereby opening the door to endless tailor-made fragrances, said the team.

It looks like the future of odor mixtures smells good!