Loss of smell and taste validated as COVID-19 symptoms in patients with high recovery rate

Loss of smell and taste has been anecdotally linked to COVID-19 infections. In a study published April 12, 2020 in the journal International Forum of Allergy & Rhinology, researchers at UC San Diego Health report the first empirical findings that strongly associate sensory loss with COVID-19, the respiratory disease caused by the novel coronavirus.

"Based on our study, if you have smell and taste loss, you are more than 10 times more likely to have COVID-19 infection than other causes of infection. The most common first sign of a COVID-19 infection remains fever, but fatigue and loss of smell and taste follow as other very common initial symptoms," said Carol Yan, MD, an otolaryngologist and head and neck surgeon at UC San Diego Health. "We know COVID-19 is an extremely contagious virus. This study supports the need to be aware of smell and taste loss as early signs of COVID-19."

Yan and colleagues surveyed 1,480 patients with flu-like symptoms and concerns regarding potential COVID-19 infection who underwent testing at UC San Diego Health from March 3 through March 29, 2020. Within that total, 102 patients tested positive for the virus and 1,378 tested negative. The study included responses from 59 COVID-19-positive patients and 203 COVID-19-negative patients.

Yan said the study demonstrated the high prevalence and unique presentation of certain sensory impairments in patients positive with COVID-19. Of those who reported loss of smell and taste, the loss was typically profound, not mild. But encouragingly, the rate of recovery of smell and taste was high and occurred usually within two to four weeks of infection.

"Our study not only showed that the high incidence of smell and taste is specific to COVID-19 infection, but we fortunately also found that for the majority of people sensory recovery was generally rapid," said Yan. "Among the Covid-19 patients with smell loss, more than 70 percent had reported improvement of smell at the time of survey and of those who hadn't reported improvement, many had only been diagnosed recently."

Sensory return typically matched the timing of disease recovery. Interestingly, the researchers found that persons who reported experiencing a sore throat more often tested negative for COVID-19.

In an effort to decrease risk of virus transmission, UC San Diego Health now includes loss of smell and taste as a screening requirement for visitors and staff, as well as a marker for testing patients who may be positive for the virus.

Other known symptoms of COVID-19 include fever, fatigue, cough and difficulty breathing. Respondents in Yan's study were most often persons with milder forms of COVID-19 infection who did not require hospitalization or intubation. The findings, she said, underline the importance of identifying early or subtle symptoms of COVID-19 infection in people who may be at risk of transmitting the disease as they recuperate within the community.

"It is our hope that with these findings other institutions will follow suit and not only list smell and taste loss as a symptom of COVID-19, but use it as a screening measure for the virus across the world," Yan said.

Co-authors include: Farhoud Faraji, Divya P. Prajapti, Christine E. Boone and Adam S. DeConde, all at UC San Diego.

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Story Source:

Materials provided by University of California - San Diego. Original written by Jeanna Vazquez. Note: Content may be edited for style and length.

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Journal Reference:

1. Carol H. Yan, Farhoud Faraji, Divya P. Prajapati, Christine E. Boone, Adam S DeConde. Association of chemosensory dysfunction and Covid-19 in patients presenting with influenza-like symptoms. International Forum of Allergy & Rhinology, 2020; DOI: 10.1002/alr.22579

Normal resting heart rate appears to vary widely from person to person

Monitoring heart rate (stock image).

A person's normal resting heart rate is fairly consistent over time, but may vary from others' by up to 70 beats per minute, according to analysis of the largest dataset of daily resting heart rate ever collected. Giorgio Quer of the Scripps Research Translational Institute in La Jolla, California, and colleagues present these findings in the open-access journal PLOS ONE on February 5, 2020 as part of an upcoming PLOS Collection on Digital Health Technology.

A routine visit to the doctor usually involves a measurement of resting heart rate, but such measurements are rarely actionable unless they deviate significantly from a "normal" range established by population-level studies. However, wearables that track heart rate now provide the opportunity to continuously monitor heart rate over time, and identify normal resting heart rates at the individual level.

In the largest study of its kind to date, Quer and colleagues retrospectively analyzed de-identified heart rate data from wearables worn for a median of 320 days by 92,457 people from across the U.S. Nearly 33 million days' worth of heart rate data were collected in total. The researchers used the data to examine variations in resting heart rate for individuals over time, as well as between individuals with different characteristics.

The analysis showed that one person's mean daily resting heart rate may differ by up to 70 beats per minute from another person's normal rate. Taken together, age, sex, body mass index (BMI), and average daily sleep duration accounted for less than 10 percent of the observed variation between individuals.

The authors observed also a small seasonal trend in the resting heart rate, with slightly higher values observed in January and slightly lower values in July. The researchers also found that some individuals may occasionally experience brief periods when their resting heart rate differs by 10 or more beats per minute from their normal range.

These findings suggest the potential value of further research to investigate whether tracking a person's daily resting heart rate could enable earlier detection of clinically important changes.

The authors add: "Day-to-day changes in resting heart rate could be the first true, individualized digital vital sign, which is only now possible to measure thanks to wearable sensor technologies. We analyzed the extent of inter- and intra-individual changes in resting heart rate over a prolonged period of time, showing distinct patterns of variation according to age and sex, time of the year, average sleep duration and body mass index. These variations in resting heart rate may allow for the identification of early unexpected changes in an individuals' health."

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Materials provided by PLOS. Note: Content may be edited for style and length.

Is the Universe Expanding at an Accelerated Rate?

A new study challenges the cosmological model and suggests that the universe is not expanding at an accelerated rate.

The standard model of cosmology assumes that the universe is isotropic with no preferred direction and no preferred frame of reference; that is, we are not special and our position in the universe is not from a privileged vantage point. Within this framework, observational data led us to the conclusion that 70% of the universe is expanding at an accelerated rate, and this accelerating force is due to an unknown form of energy known as ‘dark energy’. This so-called ‘dark energy’ is now thought to be due to quantum fluctuations of the vacuum energy.

However, a new study by a team of European scientists explored these ideas further. They wanted to see what would happen when they measure the deceleration parameter – the measurement of cosmic acceleration – from our own ‘special’ frame of reference.

The expansion of the universe is measured in terms of the Hubble constant, which is currently measured by two different methods. One method looks at the early universe through the observation of the Cosmic Microwave Background (CMB) and the other method looks at the local universe through the light emitted by galaxies, Cepheid variables and/or Type 1a supernovae. It was the latter method that led to the conclusion that the universe was expanding at an accelerating rate, resulting in astrophysicists Adam Reiss, Brian Paul Schmidt and Saul Perlmutter receiving the 2011 Nobel Prize in Physics.

However, in each case, the measurements are taken in the framework of the cosmological model which assumes that the universe is isotropic and homogeneous. This assumption is contradicted by the inhomogeneous distribution of galaxies and the lack of correlations on large angular scales, with the only confirmation coming from studies of the early universe through observed temperature fluctuations in the CMB radiation. It has therefore been suggested that this isotropic and homogeneous universe only exists at the larger scales, although this has yet to be confirmed.

The team therefore decided to see what happens when they remove this assumption from their analysis and measure the expansion in our own ‘heliocentric’ frame of reference.

“In the absence of any evidence of convergence to the CMB rest frame, this assumption is unjustified since it is very possible that the observed bulk flow stretches out to much larger scales.”
– Jacques Colin, Roya Mohayaee, Mohammed Rameez and Subir Sarkar

Utilising the latest extended sample size of supernovae data from the Joint Lightcurve Analysis catalogue, they were able to extract the redshifts for 740 Type 1a supernovae. To convert from a heliocentric frame of reference to a CMB frame of reference, the observed redshifts are generally corrected for ‘peculiar’ velocities – that is, velocities relative to a standard frame of rest. Therefore, to obtain the redshifts in our local frame of reference – the heliocentric frame – these corrections had to be undone.

Intriguingly, their results showed that the acceleration is a relatively local effect with a significant dipole component directed along the direction we are moving with respect to the CMB. This dipole component, in alignment with the CMB dipole moment, rejects the assumption of isotropy. It could therefore be that the cosmic acceleration inferred from supernovae observations is not due to dark energy and instead due to us being tilted observers located in a bulk flow.

RSF in perspective

Everything in the universe – including the universe itself – is in a continuous dance of expansion, contraction and rotation. This is true from the smallest system, to fundamental particles, to stars and galaxies, and right up to the universe itself. Depending on our perspective, the different systems will appear as coherent systems within systems or as areas of apparent randomness. So, although the universe is expanding, it could appear to be accelerating or decelerating depending on the scale of the observation and the vantage point of the observer.

First recording of a blue whale's heart rate

Blue whale

Encased in a neon orange plastic shell, a collection of electronic sensors bobbed along the surface of the Monterey Bay, waiting to be retrieved by Stanford University researchers. A lunchbox-sized speck in the vast waters, it held cargo of outsized importance: the first-ever recording of a blue whale's heart rate.

This device was fresh off a daylong ride on Earth's largest species -- a blue whale. Four suction cups had secured the sensor-packed tag near the whale's left flipper, where it recorded the animal's heart rate through electrodes embedded in the center of two of the suction feet. The details of this tag's journey and the heart rate it delivered were published Nov. 25 in Proceedings of the National Academy of Sciences.

"We had no idea that this would work and we were skeptical even when we saw the initial data. With a very keen eye, Paul Ponganis -- our collaborator from the Scripps Institution of Oceanography -- found the first heart beats in the data," said Jeremy Goldbogen, assistant professor of biology in the School of Humanities Sciences at Stanford and lead author of the paper. "There were a lot of high fives and victory laps around the lab."

Analysis of the data suggests that a blue whale's heart is already working at its limit, which may explain why blue whales have never evolved to be bigger. The data also suggest that some unusual features of the whale's heart might help it perform at these extremes. Studies like this add to our fundamental knowledge of biology and can also inform conservation efforts.

"Animals that are operating at physiological extremes can help us understand biological limits to size," said Goldbogen. "They may also be particularly susceptible to changes in their environment that could affect their food supply. Therefore, these studies may have important implications for the conservation and management of endangered species like blue whales."

Penguins to whales

A decade ago, Goldbogen and Ponganis measured the heart rates of diving emperor penguins in Antarctica's McMurdo Sound. For years after, they wondered whether a similar task could be accomplished with whales.

"I honestly thought it was a long shot because we had to get so many things right: finding a blue whale, getting the tag in just the right location on the whale, good contact with the whale's skin and, of course, making sure the tag is working and recording data," said Goldbogen.

The tag performed well on smaller, captive whales, but getting it near a wild blue whale's heart is a different task. For one thing, wild whales aren't trained to flip belly-up. For another, blue whales have accordion-like skin on their underside that expands during feeding, and one such gulp could pop the tag right off.

"We had to put these tags out without really knowing whether or not they were going to work," recalled David Cade, a recent graduate of the Goldbogen Lab who is a co-author of the paper and who placed the tag on the whale. "The only way to do it was to try it. So we did our best."

Cade stuck the tag on his first attempt and, over time, it slid into a position near the flipper where it could pick up the heart's signals. The data it captured showed striking extremes.

When the whale dove, its heart rate slowed, reaching an average minimum of about four to eight beats per minute -- with a low of two beats per minute. At the bottom of a foraging dive, where the whale lunged and consumed prey, the heart rate increased about 2.5 times the minimum, then slowly decreased again. Once the whale got its fill and began to surface, the heart rate increased. The highest heart rate -- 25 to 37 beats per minutes -- occurred at the surface, where the whale was breathing and restoring its oxygen levels.

An elastic heart

This data was intriguing because the whale's highest heart rate almost outpaced predictions while the lowest heart rate was about 30 to 50 percent lower than predicted. The researchers think that the surprisingly low heart rate may be explained by a stretchy aortic arch -- part of the heart that moves blood out to the body -- which, in the blue whale, slowly contracts to maintain some additional blood flow in between beats. Meanwhile, the impressively high rates may depend on subtleties in the heart's movement and shape that prevent the pressure waves of each beat from disrupting blood flow.

Looking at the big picture, the researchers think the whale's heart is performing near its limits. This may help explain why no animal has ever been larger than a blue whale -- because the energy needs of a larger body would outpace what the heart can sustain.

Now, the researchers are hard at work adding more capabilities to the tag, including an accelerometer, which could help them better understand how different activities affect heart rate. They also want to try their tag on other members of the rorqual whale group, such as fin whales, humpbacks and minke whales.

"A lot of what we do involves new technology and a lot of it relies on new ideas, new methods and new approaches," said Cade. "We're always looking to push the boundaries of how we can learn about these animals."

Additional Stanford co-authors include graduate students Max Czapanskiy, James Fahlbusch, William Gough and Shirel Kahane-Rapport and postdoctoral fellow Matt Savoca. Ponganis is senior author of the paper and additional co-authors are from Cascadia Research Collective; the University of California, Santa Cruz; and Scripps Institution of Oceanography. Goldbogen is also a member of Stanford Bio-X.

This research was funded by the Office of Naval Research, a Terman Fellowship from Stanford University and the John B. McKee Fund at Scripps Institution of Oceanography.

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Materials provided by Stanford University. Original written by Taylor Kubota. Note: Content may be edited for style and length.