The chemical controlling life and death in hair follicles

 A single chemical is key to controlling when hair follicle cells divide, and when they die. This discovery could not only treat baldness, but ultimately speed wound healing because follicles are a source of stem cells.

Most cells in the human body have a specific form and function determined during embryonic development that does not change. For example, a blood cell cannot turn into a nerve cell, or vice versa. Stem cells, however, are like the blank tiles in a game of Scrabble; they can turn into other types of cells.

Their adaptability makes them useful for repairing damaged tissue or organs.

"In science fiction when characters heal quickly from injuries, the idea is that stem cells allowed it," said UC Riverside mathematical biologist and study co-author Qixuan Wang.

"In real life, our new research gets us closer to understanding stem cell behavior, so that we can control it and promote wound healing," Wang said. This research is detailed in a recent Biophysical Journal article.

The liver and stomach regenerate themselves in response to wounds. However, Wang's team studied hair follicles because they're the only organ in humans that regenerates automatically and periodically, even without injury.

The researchers determined how a type of protein, TGF-beta, controls the process by which cells in hair follicles, including stem cells, divide and form new cells, or orchestrate their own death -- eventually leading to the death of the whole hair follicle.

"TGF-beta has two opposite roles. It helps activate some hair follicle cells to produce new life, and later, it helps orchestrate apoptosis, the process of cell death," Wang said.

As with many chemicals, it is the amount that makes the difference. If the cell produces a certain quantity of TGF-beta, it activates cell division. Too much of it causes apoptosis.

No one is entirely sure why follicles kill themselves. Some hypotheses suggest it is an inherited trait from animals shedding fur to survive hot summer temperatures or trying to camouflage.

"Even when a hair follicle kills itself, it never kills its stem cell reservoir. When the surviving stem cells receive the signal to regenerate, they divide, make new cell and develop into a new follicle," Wang said.

If scientists can determine more precisely the way TGF-beta activates cell division, and how the chemical communicates with other important genes, it might be possible to activate follicle stem cells and stimulate hair growth.

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Study finds why many IVF embryos fail to develop

 In humans, a fertilized egg is no guarantee of reproductive success. Most embryos stop developing and perish within days of fertilization, usually because they have an abnormal number of chromosomes. Now, researchers at Columbia University Vagelos College of Physicians and Surgeons have found that most of these mistakes are due to spontaneous errors in DNA replication in the earliest phase of cell division.

The findings provide new insights into the basic biology of human reproduction and in the long term could lead to improvements in the success rate of in vitro fertilization (IVF). The study was published online July 19 in the journal Cell.

Challenging task for early embryos

Approximately 24 hours after a human egg is fertilized, the process of cell division begins. During cell division, the entire genome -- 46 chromosomes containing more than 3 billion base pairs of DNA -- must be faithfully duplicated. The duplicate sets of chromosomes must then be separated so that each daughter cell receives a complete set.

In many human embryos created for IVF, something goes wrong and some cells within the embryo have too few or too many chromosomes.

"Duplicating the genome is a challenging task for the early embryo," says study leader Dieter Egli, PhD, the Maimonides Assistant Professor of Developmental Cell Biology (in pediatrics) at Columbia University Vagelos College of Physicians and Surgeons.

Researchers have long theorized that errors occur during the final phase of cell division, when the duplicate sets of chromosomes separate into two identical daughter cells. Most of these failures were attributed to issues with the microtubule spindle, the apparatus that pulls the two sets of chromosomes apart.

But Egli's studies found that chromosomal abnormalities stem from errors that occur much earlier in the process of cell division when the genome's DNA is duplicated. If the DNA is not copied precisely, his studies found, the spindle malfunctions and places the wrong number of chromosomes into each daughter cell. When DNA duplication is abnormal, the spindle does not function normally. "This has largely been overlooked in previous studies -- because why would the embryo allow the integrity of the genome to be compromised when this is such a critical requirement for normal development?" Egli says.

Though the studies were conducted with embryos created in a petri dish -- including from individuals undergoing IVF and egg donors who were not seeking fertility treatment -- the same problems may contribute to the failure of embryos created in natural human reproduction.

Clues to source of DNA errors

The source of DNA copying errors in embryos appears to spring from obstacles within the DNA's double helix. Though the precise reason for these obstacles is not yet known, they cause duplication of the DNA to pause, or even stop, which results in DNA breakage and an abnormal number of chromosomes.

Spontaneous DNA errors can occur as early as the first cycle of cell division in human embryos, the researchers found, as well as in subsequent cell divisions. If too many cells in the early embryo are affected by chromosomal abnormalities, the embryo cannot develop further.

IVF

Most human embryos created for IVF stop developing within days after fertilization. This inefficiency of human development is an obstacle to successful fertility treatments.

"Many women undergoing fertility treatment require multiple IVF cycles in order to get pregnant, and some never get pregnant at all. Not only is this enormously expensive, it's emotionally taxing," says Jenna Turocy, MD, a fertility specialist at Columbia University Fertility Center and a co-author of the study.

The researchers are planning additional studies looking at DNA damage during replication in the hope of understanding normal and disease-causing variations in the human germ line. In the long term, these studies may lead to methods to reduce the risk of genetic abnormalities and embryo attrition for patients undergoing IVF.

Source: ScienceDaily

During sleep the brain's reaction to sound remains strong

 A new discovery from Tel Aviv University may provide a key to a great scientific enigma: How does the awake brain transform sensory input into a conscious experience? The groundbreaking study relied on data collected from electrodes implanted, for medical purposes, deep in the human brain. The information was utilized to examine differences between the response of the cerebral cortex to sounds in sleep vs. wakefulness, at a resolution of single neurons.

The researchers were surprised to discover that the brain's response to sound remains powerful during sleep in all parameters but one: the level of alpha-beta waves associated with attention to the auditory input and related expectations. This means that during sleep, the brain analyzes the auditory input but is unable to focus on the sound or identify it, and therefore no conscious awareness ensues.

The study was led by Dr. Hanna Hayat and with major contribution from Dr. Amit Marmelshtein, at the lab of Prof. Yuval Nir from the School of Medicine, the Sagol School of Neuroscience, and the Department of Biomedical Engineering, and co-supervised by Prof. Itzhak Fried from the UCLA Medical Center. Other participants included: Dr. Aaron Krom and Dr. Yaniv Sela from Prof. Nir's group, and Dr. Ido Strauss and Dr. Firas Fahoum from the Tel Aviv Sourasky Medical Center (Ichilov). The paper was published in the journal Nature Neuroscience.

Prof. Nir: "This study is unique in that it builds upon rare data from electrodes implanted deep inside the human brain, enabling high-resolution monitoring, down to the level of individual neurons, of the brain's electrical activity. For understandable reasons, electrodes cannot be implanted in the brain of living humans just for the sake of scientific research. But in this study, we were able to utilize a special medical procedure in which electrodes were implanted in the brains of epilepsy patients, monitoring activity in different parts of their brain for purposes of diagnosis and treatment. The patients volunteered to help examine the brain's response to auditory stimulation in wakefulness vs. sleep."

The researchers placed speakers emitting various sounds at the patients' bedside and compared data from the implanted electrodes -- neural activity and electrical waves in different areas of the brain -- during wakefulness vs. various stages of sleep. Altogether, the team collected data from over 700 neurons, about 50 neurons in each patient, over the course of 8 years.

Dr. Hayat: "After sounds are received in the ear, the signals are relayed from one station to the next within the brain. Until recently it was believed that during sleep these signals decay rapidly once they reach the cerebral cortex. But looking at the data from the electrodes, we were surprised to discover that the brain's response during sleep was much stronger and richer than we had expected. Moreover, this powerful response spread to many regions of the cerebral cortex. The strength of brain response during sleep was similar to the response observed during wakefulness, in all but one specific feature, where a dramatic difference was recorded: the level of activity of alpha-beta waves."

The researchers explain that alpha-beta waves (10-30Hz) are linked to processes of attention and expectation that are controlled by feedback from higher regions in the brain. As signals travel 'bottom-up' from the sensory organs to higher regions, a 'top-down' motion also occurs: the higher regions, relying on prior information that had accumulated in the brain, act as a guide, sending down signals to instruct the sensory regions as to which input to focus on, which should be ignored, etc. Thus, for example, when a certain sound is received in the ear, the higher regions can tell whether it is new or familiar, and whether it deserves attention or not. This kind of brain activity is manifested in the suppression of alpha-beta waves, and indeed, previous studies have shown a high level of these waves in states of rest and anesthesia. According to the current study, the strength of alpha-beta waves is the main difference between the brain's response to auditory inputs in states of wakefulness vs. sleep.

Prof Nir summarizes: "Our findings have wide implications beyond this specific experiment. First, they provide an important key to an ancient, fascinating enigma: What is the secret of consciousness? What is the 'X-factor', the brain activity that is unique to consciousness, allowing us to be aware of things happening around us when we are awake, and disappearing when we sleep? In this study we discovered a new lead, and in future research we intend to further explore the mechanisms responsible for this difference.

Source: ScienceDaily

Major step forward in fabricating an artificial heart, fit for a human

 Heart disease -- the leading cause of death in the U.S. -- is so deadly in part because the heart, unlike other organs, cannot repair itself after injury. That is why tissue engineering, ultimately including the wholesale fabrication of an entire human heart for transplant, is so important for the future of cardiac medicine.

To build a human heart from the ground up, researchers need to replicate the unique structures that make up the heart. This includes recreating helical geometries, which create a twisting motion as the heart beats. It's been long theorized that this twisting motion is critical for pumping blood at high volumes, but proving that has been difficult, in part because creating hearts with different geometries and alignments has been challenging.

Now, bioengineers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have developed the first biohybrid model of human ventricles with helically aligned beating cardiac cells, and have shown that muscle alignment does, in fact, dramatically increases how much blood the ventricle can pump with each contraction.

This advancement was made possible using a new method of additive textile manufacturing, Focused Rotary Jet Spinning (FRJS), which enabled the high-throughput fabrication of helically aligned fibers with diameters ranging from several micrometers to hundreds of nanometers. Developed at SEAS by Kit Parker's Disease Biophysics Group, FRJS fibers direct cell alignment, allowing for the formation of controlled tissue engineered structures.

The research is published in Science.

"This work is a major step forward for organ biofabrication and brings us closer to our ultimate goal of building a human heart for transplant," said Parker, the Tarr Family Professor of Bioengineering and Applied Physics at SEAS and senior author of the paper.

This work has its roots in a centuries old mystery. In 1669, English physician Richard Lower -- a man who counted John Locke among his colleagues and King Charles II among his patients -- first noted the spiral-like arrangement of heart muscles in his seminal work Tractatus de Corde.

Over the next three centuries, physicians and scientists have built a more comprehensive understanding of the heart's structure but the purpose of those spiraling muscles has remained frustratingly hard to study.

In 1969, Edward Sallin, former chair of the Department of Biomathematics at the University of Alabama Birmingham Medical School, argued that the heart's helical alignment is critical to achieving large ejection fractions -- the percentage of how much blood the ventricle pumps with each contraction.

"Our goal was to build a model where we could test Sallin's hypothesis and study the relative importance of the heart's helical structure," said John Zimmerman, a postdoctoral fellow at SEAS and co-first author of the paper.

To test Sallin's theory, the SEAS researchers used the FRJS system to control the alignment of spun fibers on which they could grow cardiac cells.

The first step of FRJS works like a cotton candy machine -- a liquid polymer solution is loaded into a reservoir and pushed out through a tiny opening by centrifugal force as the device spins. As the solution leaves the reservoir, the solvent evaporates, and the polymers solidify to form fibers. Then, a focused airstream controls the orientation of the fiber as they are deposited on a collector. The team found that by angling and rotating the collector, the fibers in the stream would align and twist around the collector as it spun, mimicking the helical structure of heart muscles.

The alignment of the fibers can be tuned by changing the angle of the collector.

"The human heart actually has multiple layers of helically aligned muscles with different angles of alignment," said Huibin Chang, a postdoctoral fellow at SEAS and co-first author of the paper. "With FRJS, we can recreate those complex structures in a really precise way, forming single and even four chambered ventricle structures."

Source: ScienceDaily

Finding the right memory strategy

 What's the best way to improve your memory as you age? Turns out, it depends, a new study suggests. But your fourth-grade math teacher may have been onto something with that phrase to help you remember how to work out a complicated problem: Please Excuse My Dear Aunt Sally.

A new study led by researchers from the University of Michigan and Penn State College of Medicine compared two approaches for people with an early form of memory loss.

The two are mnemonic strategy training, which aims to connect what someone is trying to remember to something else like a word, phrase or song (such as the Dear Aunt Sally mnemonic), and spaced retrieval training, which gradually increases the amount of time between tests of remembering something.

People with mild cognitive impairment, which can but does not always lead to a later Alzheimer's disease diagnosis, were better able to remember information when using one of these cognitive training approaches. However, the data, and brain scans that revealed which areas of the brain were more active, showed each activity works differently.

"Our research shows that we can help people with mild cognitive impairment improve the amount of information they learn and remember; however, different cognitive training approaches engage the brain in distinct ways," said lead and corresponding author Benjamin Hampstead, Ph.D. Hampstead is a professor of psychiatry at Michigan Medicine and the VA Ann Arbor Healthcare System. He directs the Research Program on Cognition and Neuromodulation Based Interventions and leads the Clinical Core and co-leads the Neuroimaging Core at the federally funded Michigan Alzheimer's Disease Research Center.

"Mnemonic strategy training increased activity in brain areas often affected by Alzheimer's disease, which likely explains why this training approach helped participants remember more information and for longer," Hampstead said "In contrast, those completing rehearsal-based training showed reduced brain activity, which suggests they were processing the information more efficiently."

Hampstead and his team worked with Krish Sathian, MBBS, Ph.D., professor and chair of Penn State's Department of Neurology and director of Penn State Neuroscience Institute. Sathian noted that cognitive training approaches are likely to become increasingly important in synergy with the new pharmacological treatments on the horizon for those with neurodegenerative disorders.

Source: ScienceDaily

A third COVID-19 booster

 Twenty different COVID-19 variants were effectively identified and neutralised after a third booster, according to the new study for which the University of Surrey provided the crucial antigenic map of variants of concern.

While the study's results suggested that immunity decreases 20 weeks after vaccination, a third booster (of the Pfizer-BioNTech vaccine, in the case of this study) helped the immune system to identify and neutralise the 20 different variants.

The antigenic map allowed the team to identify and measure how each variant impacted the immune system.

Dr Daniel Horton, co-author of the study and Reader in Veterinary Virology at the University of Surrey, said:

"The emergence of this disease and its disruptive and deadly impact on our day-to-day lives demonstrates how crucial it is for the scientific community to work together to identify and characterise infectious diseases quickly.

"The University of Surrey's contribution to this study through the mapping of the various variants is itself part of a landmark €90 million collaborative effort to tackle zoonotic diseases in Europe, reflecting our focus on understanding the inextricable links between the health of animals, humans and, indeed, the planet we all share."

The Pirbright Institute led this collaborative study with scientists from the University of Surrey, Imperial College in London and the UK Health Security Agency (UKHSA) to understand the immune response of individuals aged 70-89 who had received the Pfizer-BioNTech vaccine.

This vaccine works by triggering the immune system to create Y-shaped proteins, known as antibodies, that can stick to the spike proteins which are found on the surface of the coronavirus. If a person is infected with SARS-CoV-2, the antibodies bind the spike proteins preventing the virus from attaching to and entering the human cell, therefore helping to protect from severe disease. Antibodies also act as a beacon to alert the immune system to help fight the infection.

Dr Dalan Bailey, Head of the Viral Glycoproteins group at Pirbright, said:

"Understanding how the levels of neutralising antibodies relate to a well-defined immune response will be an important step in understanding how the immune system responds to SARS-CoV-2 and could also help in the management of Covid-19.

"This information could help us to understand whether the risk of breakthrough infections, hospitalisation and death is increased by waning immunity or new variants. Research comparing immune responses to different SARS-CoV-2 variants and understanding the role of different mutations is vital in the management of the Covid-19 pandemic and in predicting the outcome of new variants."

Source: ScienceDaily

No evidence that depression is caused by low serotonin levels

 After decades of study, there remains no clear evidence that serotonin levels or serotonin activity are responsible for depression, according to a major review of prior research led by UCL scientists.

The new umbrella review -- an overview of existing meta-analyses and systematic reviews -- published in Molecular Psychiatry, suggests that depression is not likely caused by a chemical imbalance, and calls into question what antidepressants do. Most antidepressants are selective serotonin reuptake inhibitors (SSRIs), which were originally said to work by correcting abnormally low serotonin levels. There is no other accepted pharmacological mechanism by which antidepressants affect the symptoms of depression.

Lead author Professor Joanna Moncrieff, a Professor of Psychiatry at UCL and a consultant psychiatrist at North East London NHS Foundation Trust (NELFT), said: "It is always difficult to prove a negative, but I think we can safely say that after a vast amount of research conducted over several decades, there is no convincing evidence that depression is caused by serotonin abnormalities, particularly by lower levels or reduced activity of serotonin.

"The popularity of the 'chemical imbalance' theory of depression has coincided with a huge increase in the use of antidepressants. Prescriptions for antidepressants have risen dramatically since the 1990s, with one in six adults in England and 2% of teenagers now being prescribed an antidepressant in a given year.

"Many people take antidepressants because they have been led to believe their depression has a biochemical cause, but this new research suggests this belief is not grounded in evidence."

The umbrella review aimed to capture all relevant studies that have been published in the most important fields of research on serotonin and depression. The studies included in the review involved tens of thousands of participants.

Research that compared levels of serotonin and its breakdown products in the blood or brain fluids did not find a difference between people diagnosed with depression and healthy control (comparison) participants.

Research on serotonin receptors and the serotonin transporter, the protein targeted by most antidepressants, found weak and inconsistent evidence suggestive of higher levels of serotonin activity in people with depression. However, the researchers say the findings are likely explained by the use of antidepressants among people diagnosed with depression, since such effects were not reliably ruled out.

The authors also looked at studies where serotonin levels were artificially lowered in hundreds of people by depriving their diets of the amino acid required to make serotonin. These studies have been cited as demonstrating that a serotonin deficiency is linked to depression. A meta-analysis conducted in 2007 and a sample of recent studies found that lowering serotonin in this way did not produce depression in hundreds of healthy volunteers, however. There was very weak evidence in a small subgroup of people with a family history of depression, but this only involved 75 participants, and more recent evidence was inconclusive.

Very large studies involving tens of thousands of patients looked at gene variation, including the gene for the serotonin transporter. They found no difference in these genes between people with depression and healthy controls. These studies also looked at the effects of stressful life events and found that these exerted a strong effect on people's risk of becoming depressed -- the more stressful life events a person had experienced, the more likely they were to be depressed. A famous early study found a relationship between stressful events, the type of serotonin transporter gene a person had and the chance of depression. But larger, more comprehensive studies suggest this was a false finding.

These findings together led the authors to conclude that there is "no support for the hypothesis that depression is caused by lowered serotonin activity or concentrations."

The researchers say their findings are important as studies show that as many as 85-90% of the public believes that depression is caused by low serotonin or a chemical imbalance. A growing number of scientists and professional bodies are recognising the chemical imbalance framing as an over-simplification. There is also evidence that believing that low mood is caused by a chemical imbalance leads people to have a pessimistic outlook on the likelihood of recovery, and the possibility of managing moods without medical help. This is important because most people will meet criteria for anxiety or depression at some point in their lives.

The authors also found evidence from a large meta-analysis that people who used antidepressants had lower levels of serotonin in their blood. They concluded that some evidence was consistent with the possibility that long-term antidepressant use reduces serotonin concentrations. The researchers say this may imply that the increase in serotonin that some antidepressants produce in the short term could lead to compensatory changes in the brain that produce the opposite effect in the long term.

While the study did not review the efficacy of antidepressants, the authors encourage further research and advice into treatments that might focus instead on managing stressful or traumatic events in people's lives, such as with psychotherapy, alongside other practices such as exercise or mindfulness, or addressing underlying contributors such as poverty, stress and loneliness.

Source: ScienceDaily

Researchers argue that the long human lifespan

 According to long-standing canon in evolutionary biology, natural selection is cruelly selfish, favoring traits that help promote reproductive success. This usually means that the so-called "force" of selection is well equipped to remove harmful mutations that appear during early life and throughout the reproductive years. However, by the age fertility ceases, the story goes that selection becomes blind to what happens to our bodies. After the age of menopause, our cells are more vulnerable to harmful mutations. In the vast majority of animals, this usually means that death follows shortly after fertility ends.

Which puts humans (and some species of whale) in a unique club: animals that continue to live long after their reproductive lives end. How is it that we can live decades in selection's shadow?

"From the perspective of natural selection, long post-menopausal life is a puzzle," said UC Santa Barbara anthropology professor Michael Gurven. In most animals, including chimpanzees -- our closest primate brethren -- this link between fertility and longevity is very pronounced, where survival drops in sync with the ability to reproduce. Meanwhile in humans, women can live for decades after their ability to have children ends. "We don't just gain a few extra years -- we have a true post-reproductive life stage," Gurven said.

In a paper published in the Proceedings of the National Academy of Sciences, senior author Gurven, with former UCSB postdoctoral fellow and population ecologist Raziel Davison, challenge the longstanding view that the force of natural selection in humans must decline to zero once reproduction is complete.

They assert that a long post-reproductive lifespan is not just due to recent advancements in health and medicine. "The potential for long life is part of who we are as humans, an evolved feature of the life course," Gurven said.

The secret to our success? Our grandparents.

"Ideas about the potential value of older adults have been floating around for awhile," Gurven said. "Our paper formalizes those ideas, and asks what the force of selection might be once you take into account the contributions of older adults."

For example, one of the leading ideas for human longevity is called the Grandmother Hypothesis -- the idea that, through their efforts, maternal grandmothers can increase their fitness by helping improve the survival of their grandchildren, thereby enabling their daughters to have more children. Such fitness effects help ensure that the grandmother's DNA is passed down.

"And so that's not reproduction, but it's sort of an indirect reproduction. The ability to pool resources, and not just rely on your own efforts, is a game changer for highly social animals like humans," Davison said.

In their paper, the researchers take the kernel of that idea -- intergenerational transfers, or resource sharing between old and young -- and show that it, too, has played a fundamental role in the force of selection at different ages. Food sharing in non-industrial societies is perhaps the most obvious example.

"It takes up to two decades from birth before people produce more food than they're consuming," said Gurven, who has studied the economy and demography of the Tsimané and other indigenous groups of South America. A lot of food has to be procured and shared to get kids to the point where they can fend for themselves and be productive group members. Adults fill most of this need with their ability to obtain more food than they need for themselves, a provisioning strategy that has sustained pre-industrial societies for ages and also carries over into industrialized societies.

"In our model, the large surplus that adults produce helps improve the survival and fertility of close kin, and of other group members who reliably share their food, too," Davison said. "Viewed through the lens of food production and its effects, it turns out that the indirect fitness value of adults is also highest among reproductive-aged adults. But using demographic and economic data from multiple hunter-gatherers and horticulturalists, we find that the surplus provided by older adults also generates positive selection for their survival. We calculate all this extra fitness in late adulthood to be worth up to a few extra kids!"

Source: ScienceDaily

What causes difficulty breathing?

 The symptoms of many conditions include difficulty breathing, which can be mild or severe.

A person who is having difficulty breathing feels short of breath, has trouble inhaling or exhaling, or feels as though they cannot get enough oxygen.

Very often, people experience trouble breathing after exercising or when they feel anxious. In some cases, breathing difficulties can signal a medical condition, so it is essential to work out the cause.

In this article, we look at the possible reasons why people might experience difficulty breathing. We also cover the diagnosis, treatment, and prevention of this symptom.

Colds or flu

People with a common cold or the flu may have difficulty breathing. These illnesses cause the following symptoms, which can make breathing more difficult:

• stuffy nose
• a sore throat
• inflamed airways
• sinusitis
• excess mucus in the airways

When a cold, flu, or chest infection is the cause of breathing difficulties, the symptoms should clear up when the illness resolves. Learn how to ease the symptoms of a cold here.

Anxiety

Anxiety can cause physical symptoms, including shortness of breath or breathing difficulties. A person’s breath is likely to return to normal once their anxiety eases.

Other symptoms of anxiety include:

• feeling nervous or on edge
• raised heart rate
• a sense of doom
• fatigue
• difficulty concentrating
• digestive problems

People may sometimes experience extreme anxiety or panic attacks that resemble a heart attack. Other symptoms of a panic attack can include:

• a raised or pounding heartbeat
• a feeling of choking
• sweating
• chest pain
• numbness or tingling
• chills or heat sensations

Learn about the differences between a panic attack and a heart attack here.

Asthma

Asthma is a chronic disease that causes the airways leading to the lungs to become inflamed.

As with other chronic conditions, a person’s asthma will flare from time to time, usually as a result of exposure to a trigger. Triggers can vary between people but could include exercise, smoke, or particular allergens.

Common asthma symptoms include:

• wheezing
• chronic coughing
• tightness in the chest
• difficulty sleeping due to coughing or wheezing

Choking

Choking occurs when an object becomes lodged in a person’s throat. The object could be a larger piece of food, a toy, or another nonedible item that a child may typically put in their mouth.

Choking can be life-threatening if the object remains in the person’s mouth. However, if the removal of the object is rapid, a person will be able to resume normal breathing relatively quickly.

Common symptoms of choking include:

• gagging following the initial inhalation of the object
• coughing
• wheezing
• a panicked look and frantic gesturing toward the throat

If the object entirely blocks the throat, the person will be unable to breathe, which is a medical emergency.

Signs that the object is preventing breathing include:

• passing out
• lips turning blue
• lack of breathing
• inability to speak

Breathing difficulty after eating

Several health conditions could potentially cause a person to have trouble breathing after eating.

For example, according to the COPD Foundation, shortness of breath after eating a more substantial meal is common for people with chronic obstructive pulmonary disease (COPD) because the food can push against the diaphragm and make it difficult to breathe in deeply.

Acid reflux may also cause shortness of breath. It can have this effect because stomach acid works its way up the esophagus and irritates the lining, which may cause inspiratory breathing problems. Acid reflux may also cause a chronic cough.

Learn more about shortness of breath after eating here.

Lack of exercise or obesity

A person who has obesity or does not exercise regularly may experience periods during which they have difficulty breathing.

Short periods of exertion can cause a person to feel out of breath.

If weight or a lack of exercise is the cause of breathing difficulty, starting an exercise regimen and following a healthful diet can significantly contribute to reducing or eliminating the problem.

COPD

COPD is a term that describes several lung disorders, including chronic asthma, emphysema, and chronic bronchitis. COPD symptoms may worsen at night due to changes in the way that a person breathes while sleeping.

COPD can cause a range of symptoms, such as:

• shortness of breath
• chest pain
• coughing
• fatigue, as a result of reduced oxygen in the blood

Emphysema

According to the American Lung Association, emphysema is one of the diseases under the COPD umbrella.

Emphysema thins and destroys the alveoli, or air sacs, in the lungs. The inhalation of cigarette smoke is a leading cause of this condition.

The primary symptoms of emphysema include:

• coughing
• increased phlegm
• shortness of breath during activities

Anaphylaxis

Anaphylaxis is a severe allergic reaction. It is a life-threatening condition that requires immediate medical attention. Anaphylaxis progresses quickly, but it has some early warning signs and symptoms.

These may include:

• hives
• tightness in the throat
• trouble breathing
• a hoarse voice
• vomiting
• abdominal pain
• cardiac arrest
• dizziness
• rapid heartbeat
• nausea
• low blood pressure
• a sense of doom

Pregnancy

As pregnancy progresses, the fetus becomes bigger and can start to push on surrounding organs and muscles. These include the diaphragm, which is a muscle directly below the lungs that helps a person take deep breaths.

If the uterus pushes against the diaphragm, this can make it more difficult for the person to take deep breaths.

In addition to the expanding uterus, people may experience difficulty breathing during pregnancy due to progesterone, a hormone that the body produces in larger quantities during pregnancy. Progesterone can make someone feel as though they cannot take a deep breath.

If other symptoms arise, pregnancy is unlikely to be the cause of breathing issues, and it is best to see a doctor to determine the cause.

Heart attack

According to the American Heart AssociationTrusted Source, difficulty breathing is one of the common warning signs of a heart attack. Therefore, anyone experiencing this symptom should pay attention to any other symptoms that occur.

If a person experiences the following symptoms, they should get medical attention immediately:

• chest discomfort
• trouble breathing
• discomfort in the back, jaw, neck, stomach, or one or both arms
• lightheadedness
• cold sweats
• nausea.

Source - Medical News Today

Low and normal blood oxygen levels: What to know

Blood oxygen level is the amount of oxygen circulating in the blood. Red blood cells carry most of the oxygen, collecting it from the lungs and delivering it to all parts of the body.

The body closely monitors blood oxygen levels to keep them within a specific range so that there is enough oxygen for the needs of every cell.

A person’s blood oxygen level is an indicator of how well the body distributes oxygen from the lungs to the cells, and it can be important for people’s health.

Normal and low blood oxygen levels

A healthy blood oxygen level varies between 75 and 100 millimeters of mercury (mm Hg).

When arterial blood gas (ABG) test results reveal an oxygen level below 60 mm HgTrusted Source, the medical community considers it low. In some cases, people with these results may require oxygen supplementation.

A blood oxygen level that is too low compared with the average level of a healthy person can be a sign of a condition known as hypoxemia. This develops when the body has difficulty delivering oxygen to all of its cells, tissues, and organs.

Oxygen saturation

Oxygen saturation refers to the percentage of oxygen in a person’s blood. Medical professionals often use a device called a pulse oximeter for either a quick test or continuous monitoring. The device can attach to the person’s fingertip.

A healthy oxygen saturation level ranges between 95% and 100%Trusted Source. If a person’s levels drop below this range, they may experience symptoms associated with a lack of oxygen, such as trouble breathing and confusion.

How is blood oxygen level measured?

An ABG test is the most effective way to monitor blood oxygen levels. This test involves taking a blood sample from an artery, usually in the wrist. This procedure is very accurate, but it can be a little painful.

Doctors carry out ABG tests in a hospital. However, people can also test themselves at home using a small device known as a pulse oximeter.

A pulse oximeter is a small clip that often attaches to a finger, although it will also work on an ear or a toe. It measures blood oxygen indirectly by light absorption through a person’s pulse.

Although the pulse oximeter test is easier, quicker, and less painful than the ABG test, it is not as accurate. Several factors can interfere with the results, includingTrusted Source:

• dirty fingers
• bright lights
• darker skin tones
• nail polish
• poor circulation to the extremities

Learn how to choose the best pulse oximeter to purchase.

Symptoms of low blood oxygen levels

Low blood oxygen levels can result in abnormal circulation and causeTrusted Source the following symptoms:

• shortness of breath
• headaches
• restlessness
• dizziness
• rapid breathing
• chest pain
• confusion
• high blood pressure
• lack of coordination
• visual disorders
• sense of euphoria
• rapid heartbeat

Learn more about the symptoms of poor circulation.

Causes of low blood oxygen

The medical term for low blood oxygen is hypoxemia. It may happen due to:

• insufficient oxygen in the air
• inability of the lungs to inhale and send oxygen to all cells and tissues
• inability of the bloodstream to circulate to the lungs, collect oxygen, and transport it around the body

Conditions that can lead to hypoxemia

Several medical conditions and situations can contributeTrusted Source to the above factors, including:

• asthma
• heart diseases, including congenital heart disease
• high altitude
• anemia
• COVID-19Trusted Source
• chronic obstructive pulmonary disease (COPD)
• interstitial lung disease
• emphysema
• acute respiratory distress syndrome (ARDS)
• pneumonia
• obstruction of an artery in the lung
• pulmonary fibrosis, or scarring and damage to the lungs
• presence of air or gas in the chest that makes the lungs collapse
• excess fluid in the lungs
• sleep apnea, which involves breathing interruptions during sleep
• certain medications, including some narcotics and pain relievers

When to contact a doctor

People should contact a doctor if they:

• experience severe and sudden shortness of breath
• experience shortness of breath when at rest
• have severe shortness of breath that worsens during exercise or physical activity
• wake suddenly with shortness of breath or a feeling of choking
• are at high altitude and experience severe shortness of breath with a cough, rapid heartbeat, and fluid retention

Treatment

The treatment options for low blood oxygen levels include supplemental oxygen. Doctors can administer oxygen therapy in an office, or they can prescribe or recommend the use of home oxygen therapy (HOT).

A range of devices is available for delivering and monitoring HOT, but some require a prescription.

People can make lifestyle adjustments to reduce the symptoms of low oxygen levels, as well as improve their general health and quality of life. Changes that will likely be beneficial include:

• quitting smoking
• avoiding secondhand smoke
• eating a nutritious diet containing plenty of fruits, whole grains, lean protein, and vegetables
• exercising regularly

Outlook

Many conditions can cause low blood oxygen levels. Treating the underlying condition responsible will generally improve blood oxygen levels.

People living with chronic lung diseases, such as COPD, and those who catch COVID-19 may need regular blood oxygen monitoring.

A person with low blood oxygen can also make lifestyle changes, such as adjusting their dietary and exercise habits. In conjunction with oxygen therapy, these changes could help a person raise their oxygen saturation levels.

Summary

A person’s blood oxygen level refers to the amount of oxygen circulating in their blood. A person can measure their blood oxygen levels using a pulse oximeter. On a pulse oximeter, doctors consider levels under 95% to be low.

Several conditions can cause low blood oxygen levels, including asthma, anemia, and COVID-19.

The treatment will often involve addressing the underlying cause, but doctors may sometimes also recommend oxygen therapy or lifestyle modifications.

Source - Medical News Today