Category Archives: Physiology

Physiology

Cerebral and systemic physiological effects of wearing face masks in young adults – pnas.org

Abstract

The COVID-19 pandemic led to widespread mandates requiring the wearing of face masks, which led to debates on their benefits and possible adverse effects. To that end, the physiological effects at the systemic and at the brain level are of interest. We have investigated the effect of commonly available face masks (FFP2 and surgical) on cerebral hemodynamics and oxygenation, particularly microvascular cerebral blood flow (CBF) and blood/tissue oxygen saturation (StO2), measured by transcranial hybrid near-infrared spectroscopies and on systemic physiology in 13 healthy adults (ages: 23 to 33 y). The results indicate small but significant changes in cerebral hemodynamics while wearing a mask. However, these changes are comparable to those of daily life activities. This platform and the protocol provides the basis for large or targeted studies of the effects of mask wearing in different populations and while performing critical tasks.

Many governments have mandated the wearing of face masks in response to the coronavirus disease 2019 (COVID-19) pandemic in order to mitigate the acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission. The effectiveness of this measure is currently being evaluated (1). This has led to ongoing discussions about possible adverse effects of mask wearing (e.g., dizziness, headaches, fainting), especially within the elderly, during long-term continuous mask usage and during physical activity. Chan et al. (2) reported that the arterial oxygenation (SpO2) did not change in elderly subjects after 1 h, while Law et al. (3) reported a significant effect on baseline cerebral hemodynamics and end-tidal carbon dioxide pressure (EtCO2) using functional MRI (fMRI) on middle-aged adults. No task-induced hemodynamic changes were found in this study. The bulk of these concerns arise due to potential hypercapnic effects of carbon dioxide rebreathing, which has not yet been evaluated in a thorough manner. Also, the brain function was evaluated only at the level of a surrogate of oxygen consumption. Noninvasive functional near-infrared spectroscopy (fNIRS) and functional diffuse correlation spectroscopy (fDCS) use near-infrared light to measure microvascular cerebral hemodynamics without the constraints of the fMRI scanners. When combined together, they allow us to relate cerebral blood/tissue oxygen saturation and blood flow to the cerebral oxygen metabolism. Their main disadvantage is the potential signal contamination due to the extracerebral tissues and the limited penetration depth. Nevertheless, the advantage of studying mask effects on brain function in realistic settings merits their uses for a thorough study to look at the physiology in a holistic manner.

To this end, we have investigated the effect of mask wearing (FFP2 [European Union standard, similar to N95 in North America and KN95 in China] versus surgical) on cerebral hemodynamics, blood/tissue oxygenation, and oxygen metabolism as well as the systemic physiology with a multimodal platform of custom near-infrared spectroscopies and commercial physiological monitors in healthy young adults.

Thirteen volunteers (median age: 27.0 y [23 to 33 y], six females) took part in the study. Fig. 1 summarizes the findings. Small but significant changes in cerebral blood flow (CBF) and cerebral blood oxygen saturation (StO2) were detected for both mask types: 1) CBF increased by 6.5% (95% CI: 2.6, 10.5%) for the FFP2 mask and 6.2% (95% CI: 2.4, 9.9%) for the surgical mask; 2) StO2 increased by 0.9% (95% CI: 0.2, 1.7%) for the FFP2 mask and also 0.9% (95% CI: 0.1, 1.6%) for the surgical mask; 3) total hemoglobin concentration (tHb) increased significantly only for the FFP2 mask by 0.9 M (95% CI: 0.3, 1.5 M). Changes in oxygen extraction fraction (OEF) and cerebral metabolism (CMRO2) (defined in SI Appendix) were not statistically significant: 1) OEF decreased by 1.7% (85% CI: 4.1, 0.8) for the FFP2 mask and by 2.4% (95% CI: 4.7, 0.0) for the surgical mask; 2) CMRO2 increased by 4.5% (95% CI: 1.3, 10.4%) for the FFP2 mask and by 3.6% (95% CI: 1.7, 9.0%) for the surgical mask. None of these changes were statistically significantly different between the two mask types.

(Left) Changes in the different parameters are shown for FFP2 masks (red) and surgical masks (blue). denotes a difference and r is a ratio. The arrow indicates a significant change (P < 0.05) whose direction is an increase or a decrease. Additionally, for cerebral hemodynamics, we have reported (green) changes during typical tasks such as basic cognitive, visual, or motor tasks (4, 8) for comparison. (Right) Time series of the population mean of all parameters are shown for both mask types (same color code). Time 0 is the time when the mask was placed and the shaded area indicates the time taken for placing the mask, which was excluded from the analysis. Data to the Right of the 3-min mark (magenta) were used for analysis to allow the physiology to stabilize after placing the mask. The data were normalized to 300 s prior to the mask placement.

EtCO2 showed a significant change but was discarded since the probe was affected by the air trapped within the mask. Transcutaneous carbon dioxide partial pressure (TcCO2) and SpO2 did not significantly change due to wearing a mask, while mean arterial pressure (MAP) and heart rate (HR) increased significantly for the surgical mask by 4.1 mmHg (95% CI: 0.5, 7.6 mmHg) and 2.0 beats/min (95% CI: 1.0, 3.1 beats/min), respectively. Respiratory rate (RR) decreased significantly for the FFP2 mask by 3.2 breaths/min (95% CI: 5.4, 1.1 breaths/min). A significant difference in HR between mask types of 1.2 beats/min (95% CI: 0.0, 2.4 beats/min) was detected.

Our findings show that wearing a face mask leads to statistically significant changes in the cerebral hemodynamics and oxygenation (CBF and StO2) in healthy young subjects at rest, even for this first relatively short period of mask usage. However, the changes observed are minimal and are comparable to those typically observed during daily life (4). Within the limitations of the study, we cannot claim any concerns for mask use during daily life activities for healthy, young individuals. In order to draw a stronger conclusion, the duration of mask wearing could have been longer (harder to disentangle its effects from other physiological variables such as fatigue), the study population should be more heterogeneous representing the society in general, and the sample sizes can be increased. Another limitation is the fact that the order of the masks was fixed, therefore one should be critical about the results regarding differences in the mask types and additional differences may be revealed in the future. The noticeable differences in variance of the time traces are related to the intersubject variability, which may be related to the fit of the mask, mask types, and the individuals physiology.

Furthermore, we did not observe significant changes in TcCO2 and SpO2. The increase in MAP and HR for the surgical mask may have been caused by the discomfort of probes, placement of masks, and the order of studies. Here, we did not account for these stressors as potential confounding effects, since they are also part of daily life. This observation is further strengthened since TcCO2 did not change, i.e., the hypothesized hypercapnic effect was not observed. We stress that in the literature mainly EtCO2 is utilized as a surrogate of blood carbon dioxide levels, which, however, is influenced by the trapped carbon dioxide under the mask with standard equipment (5). TcCO2 provides insights as a better surrogate for the partial pressure of carbon dioxide.

Overall, our study provides a holistic view of understanding the potential effects of mask wearing in healthy, young adults by a thorough characterization of both the systemic physiology, the presumed driving biomarker of carbon dioxide rebreathing effect, and cerebral hemodynamics. The large intersubject variability while wearing a mask suggests that individuals may have differing responses and the platform/protocol that we introduce here could be utilized on elderly subjects or those with preexisting respiratory or cerebrovascular problems. These populations may behave differently. Finally, the potential effect of mask wearing on individuals performing critical tasks needs to be studied with future investigations. Investigations of these effects are important for policy making in order to maintain quality of life for individuals and for minimizing risks in persons carrying out critical tasks.

The study protocol was approved by the ethical committee of Hospital Clinic Barcelona and all participants signed informed consent. Young healthy adults (range for inclusion: 20 to 35 y of age) were recruited. Participants sat in a chair and read a scientific text during the experiments. The experimental paradigm involved two 10-min periods: 1) without wearing a mask and 2) with a mask. A commonly used three-layer surgical mask and a FFP2 mask (RM101 FFP2 NR, Zhejiang Yinghua Technology Co. Ltd.) were tested. Cerebral blood flow, oxygenation, and oxygen metabolism were measured bilaterally over the prefrontal cortex using transcranial diffuse correlation spectroscopy (DCS) and time-resolved near-infrared spectroscopy (TR-NIRS) (6). Changes in CBF, StO2, and tHb were determined. MAP, HR, SpO2, RR, EtCO2, and TcCO2 were monitored. Signal processing was performed with Matlab (R2019a, MathWorks) and statistical analysis (R, v4.0.3) was applied to determine whether mask wearing was leading to a significant change in the signals. Raw DCS and TR-NIRS data were fitted using the analytical solution. Artifacts were manually removed, the data were smoothed (30-s window), and the changes were averaged over both hemispheres since no difference between them was detected (P >> 0.5, paired Wilcoxon test). For further details see SI Appendix.

This work was funded by la Fundaci La Marat de TV3 (201709.31, 201724.31); Fundaci CELLEX Barcelona; Agencia Estatal de Investigacin (PHOTOMETABO, PID2019-106481RB-C31, PRE2018-085082); the Severo Ochoa (CEX2019-000910-S); laCaixa (LlumMedBcn); Instituci Centres de Recerca de Catalunya (CERCA), Agncia de Gesti d'Ajuts Universitaris i de Recerca (AGAUR)-Generalitat (2017SGR1380); RIS3CAT (CECH, 001-P-001682); LASERLAB-EUROPE V and EU Horizon 2020 (BitMap 675332, VASCOVID 101016087, LUCA 688303, TinyBrains 101017113).

Author contributions: J.B.F., L.K.F., F.S., R.D.-M., M.M., and T.D. designed research; J.B.F. and L.K.F. performed research; J.B.F. and L.K.F. analyzed data; J.B.F., F.S., and T.D. wrote the paper; J.B.F., L.K.F., F.S., R.D.-M., M.M., and T.D. interpreted data; F.S., M.M., and T.D. provided supervision; and R.D.-M. and T.D. provided administrative, technical, and material support.

Competing interest statement: T.D. and J.B.F. are inventors on relevant patents. Institut de Cincies Fotniques (ICFO) has equity ownership in the spin-off company HemoPhotonics S.L. Potential financial conflicts of interest and objectivity of research have been monitored by ICFOs Knowledge and Technology Transfer Department.

This article contains supporting information online at https://www.pnas.org/lookup/suppl/doi:10.1073/pnas.2109111118/-/DCSupplemental.

Link:
Cerebral and systemic physiological effects of wearing face masks in young adults - pnas.org

Physiology

2 US scientists win Nobel Prize in medicine for showing how we react to heat, touch – Fox17

Two American scientists have won the Nobel Prize in physiology or medicine for their discovery of receptors for temperature and touch.

The Nobel Assembly at Karolinska Institutet announced Monday morning that its awarding the honor to David Julius and Ardem Patapoutian.

Peter Barreras/Peter Barreras/Invision/AP

The Nobel Prize organization says Julius and Patapoutian solved how nerve impulses are initiated so that temperate and pressure can be perceived.

Julius utilized capsaicin, a pungent compound from chili peppers that induces a burning sensation, to identify a sensor in the nerve endings of the skin that responds to heat, according to the organization.

And Patapoutian reportedly used pressure-sensitive cells to discover a novel class of sensors that respond to mechanical stimuli in the skin and internal organs.

These discoveries launched research activities that officials say led to a rapid increase in our understanding of how the human nervous system senses heat, cold, and mechanical stimuli.

The laureates identified critical missing links in our understanding of the complex interplay between our senses and the environment, said the organization.

Julius, 65, is a physiologist who works as a professor at the University of California, San Francisco, while Patapoutian is a molecular biologist and neuroscientist at Scripps Research in La Jolla, California.

See original here:
2 US scientists win Nobel Prize in medicine for showing how we react to heat, touch - Fox17

Physiology

2021 Nobel Prize in Physiology or Medicine goes to two researchers for their discovery of receptors for temperature and touch – Chemical &…

2021 Nobel Prize in Physiology or Medicine goes to two researchers for their discovery of receptors for temperature and touch  Chemical & Engineering News

Go here to read the rest:
2021 Nobel Prize in Physiology or Medicine goes to two researchers for their discovery of receptors for temperature and touch - Chemical &...

Physiology

Why are males still the default subjects in medical research? – The Conversation AU

Women and girls account for 50% of the population, yet most health and physiology research is conducted in males.

This is especially true for fundamental research (which builds knowledge but doesnt have an application yet) and pre-clinical (animal) research. These types of research often only focus on male humans, animals and even cells.

In our discipline of exercise physiology, 6% of research studies include female-only participant groups.

So why do so many scientists seem oblivious to the existence of half of the worlds population?

Read more: Equal but not the same: a male bias reigns in medical research

Firstly, its important to understand key terminology in society and research. As referred to throughout this article, male and female are categories of sex, defined by a set of biological attributes associated with physical and physiological characteristics.

In comparison, men, women and non-binary people are categories of gender: a societal construct that encompasses behaviours, power relationships, roles and identities.

Here we discuss research on specific sexes, but further consideration of gender-diverse groups, such as transgender people, also remains a gap in science.

The main reasoning is that females are a more complicated model organism than males.

The physiological changes associated with the menstrual cycle add a whole lot of complexities when it comes to understanding how the body may respond to an external stimulus, such as taking a drug or performing a specific type of exercise.

Read more: From energy levels to metabolism: understanding your menstrual cycle can be key to achieving exercise goals

Some females use contraception, and those who do use different types. This adds to the variability between them.

Females also undergo menopause around the age of 50, another physiological change that fundamentally impacts the way the body functions and adapts.

Even when research with females is performed properly, the findings may not apply to all females. This includes whether a female individual is cisgender or gender nonconforming.

Altogether, this makes female research more time-consuming and expensive and research is nearly always limited by time and money.

Yes, because males and females are physiologically different.

This does not only involve visually obvious differences (the so-called primary sex characteristics, such as body shape or genitals), but also a whole range of hidden differences in hormones and genetics.

Theres also emerging evidence from our research team that sex differences impact epigenetics: how your behaviours and environment affect the expression of your genes.

Conducting health and physiology research in males exclusively disregards these differences. So our knowledge of the human body, which is mostly inferred from what is observed in males, may not always hold true for females.

Some diseases, such as cardiovascular (heart) disease, present differently in males and females.

Read more: Women who have heart attacks receive poorer care than men

Males and females may also metabolise drugs in a different way, meaning they may need different quantities or formulations. These drugs can have sex-specific side effects.

This may have major consequences in the way we treat diseases or the preferred drugs we use in the clinic.

Take COVID-19, for example. The severity and death rates of COVID-19 are higher in males than females. Sex differences in immunity and hormonal pathways may explain this, therefore researchers are advocating for sex-specific research to aid viral treatment.

No matter the cost or added complexity, research should be for everyone and apply to everyone. International medical research bodies are now starting to acknowledge this.

A March 2021 statement from the Endocrine Society, the international body for doctors and researchers who study hormones and treat associated problems, recognises:

Before mechanisms behind sex differences in physiology and disease can be elucidated, a fundamental understanding of sex differences that exist at baseline, is needed.

The National Institutes of Health (NIH), the largest medical research board in the United States, recently called for researchers to account for sex as a biological variable.

Unless a strong case can be made to study only one sex, studying both sexes is now a requirement to receive NIH research funding.

The Australian equivalent, the National Health and Medical Research Council (NHMRC), indirectly recommends the collection and analysis of sex-specific data in animals and humans.

However the inclusion of both sexes is not yet a requirement to receive funding in Australia.

Because sex matters, we created a freely available infographic based on our research that aims at making female health and physiology research easier to design.

It presents as a simple flow through diagram that researchers can use before starting their project and prompts them to consider questions such as:

is the phenomenon I am investigating influenced by female hormones?

should all females in my cohort use the same contraception?

on which day of the menstrual cycle should I test my participants for the most reliable result?

Depending on the answers, our infographic proposes strategies (that can be practical such as who to recruit and when or statistical) to design research that takes into account the complexity of the female body.

Its easy to follow and accessible to all. And, while initially designed for exercise physiology research, it can be applied to any type of female health and physiology research.

Read more: Medicine's gender revolution: how women stopped being treated as 'small men'

Based on our infographics, we designed a female-only, four-year research project to map the process of muscle ageing in females. Females live longer than males but, paradoxically, are more susceptible to some of the consequences of ageing. Despite lots of ageing research in males, we still know very little about the female-specific characteristics at play.

So yes, the future is female so is our research. And we hope to inspire health and physiology researchers all over the world to do the same.

Read more here:
Why are males still the default subjects in medical research? - The Conversation AU

Physiology

Department of Physiology and Biophysics Seminar – umc.edu

Main Content

When: Wednesday, September 01, 2021, from 12:00 p.m. to 1:00 p.m.Location: WebEx

Contact Info: Courtney Graham at chortongraham@umc.edu or 601-984-1820Related Link: Click here to view event flyer

Dr. Jennifer Sones, Associate Professor of Theriogenology in the Department of Physiology/ School of Medicine, will give the virtual Department of Physiology and Biophysics Seminar, Metabolic Basis of Disease in BPH/5 Mice, at noon on Wednesday, Sept. 1, online via WebEx.

Originally posted here:
Department of Physiology and Biophysics Seminar - umc.edu

Physiology

Awards and Honors Across Weill Cornell Medicine August 27, 2021 – Weill Cornell Medicine Newsroom

Dr. Dolores Lamb, who was recruited as assistant professor of molecular biology in urology, has been elected Eastern Regional Administrative Secretary at the American Association of Bioanalysts (AAB) as a member of the AAB Membership Review Committee. Dr. Lambs term began in June 2021.

Dr. Christopher Mason, co-director of theWorldQuant Initiative for Quantitative Predictionand a professor of physiology and biophysics, has been selected to serve on the National Academy of Sciences (NAS) Committee to develop the next 10 years of NASA and space medicine priorities.

Continue reading here:
Awards and Honors Across Weill Cornell Medicine August 27, 2021 - Weill Cornell Medicine Newsroom

Physiology

New imaging, machine-learning methods speed effort to reduce crops’ need for water – University of Illinois News

CHAMPAIGN, Ill. Scientists have developed and deployed a series of new imaging and machine-learning tools to discover attributes that contribute to water-use efficiency in crop plants during photosynthesis and to reveal the genetic basis of variation in those traits.

The findings are described in a series of four research papers led by University of Illinois Urbana-Champaign graduate students Jiayang (Kevin) Xie and Parthiban Prakash, and postdoctoral researchers John Ferguson, Samuel Fernandes and Charles Pignon.

The goal is to breed or engineer crops that are better at conserving water without sacrificing yield, said Andrew Leakey, a professor of plant biology and of crop sciences at the University of Illinois Urbana-Champaign, who directed the research.

Drought stress limits agricultural production more than anything else, Leakey said. And scientists are working to find ways to minimize water loss from plant leaves without decreasing the amount of carbon dioxide the leaves take in.

Plants breathe in carbon dioxide through tiny pores in their leaves called stomata. That carbon dioxide drives photosynthesis and contributes to plant growth. But the stomata also allow moisture to escape in the form of water vapor.

A new approach to analyzing the epidermis layer of plant leaves revealed that the size and shape of the stomata (lighter green pores) in corn leaves strongly influence the crops water-use efficiency.

Micrograph by Jiayang (Kevin) Xie

Edit embedded media in the Files Tab and re-insert as needed.

The amount of water vapor and carbon dioxide exchanged between the leaf and atmosphere depends on the number of stomata, their size and how quickly they open or close in response to environmental signals, Leakey said. If rainfall is low or the air is too hot and dry, there can be insufficient water to meet demand, leading to reduced photosynthesis, productivity and survival.

To better understand this process in plants like corn, sorghum and grasses of the genus Setaria, the team analyzed how the stomata on their leaves influenced plants water-use efficiency.

We investigated the number, size and speed of closing movements of stomata in these closely related species, Leakey said. This is very challenging because the traditional methods for measuring these traits are very slow and laborious.

For example, determining stomatal density previously involved manually counting the pores under a microscope. The slowness of this method means scientists are unable to analyze large datasets, Leakey said.

There are a lot of features of the leaf epidermis that normally dont get measured because it takes too much time, he said. Or, if they get measured, its in really small experiments. And you cant discover the genetic basis for a trait with a really small experiment.

To speed the work, Xie took a machine-learning tool originally developed to help self-driving cars navigate complex environments and converted it into an application that could quickly identify, count and measure thousands of cells and cell features in each leaf sample.

Jiayang (Kevin) Xie converted a machine-learning tool originally designed to help self-driving cars navigate complex environments into an application that can quickly analyze features on the surface of plant leaves.

Photo by L. Brian Stauffer

Edit embedded media in the Files Tab and re-insert as needed.

To do this manually, it would take you several weeks of labor just to count the stomata on a seasons worth of leaf samples, Leakey said. And it would take you months more to manually measure the sizes of the stomata or the sizes of any of the other cells.

The team used sophisticated statistical approaches to identify regions of the genome and lists of genes that likely control variation in the patterning of stomata on the leaf surface. They also used thermal cameras in field and laboratory experiments to quickly assess the temperature of leaves as a proxy for how much water loss was cooling the leaves.

This revealed key links between changes in microscopic anatomy and the physiological or functional performance of the plants, Leakey said.

By comparing leaf characteristics with the plants water-use efficiency in field experiments, the researchers found that the size and shape of the stomata in corn appeared to be more important than had previously been recognized, Leakey said.

Along with the identification of genes that likely contribute to those features, the discovery will inform future efforts to breed or genetically engineer crop plants that use water more efficiently, the researchers said.

The new approach provides an unprecedented view of the structure and function of the outermost layer of plant leaves, Xie said.

There are so many things we dont know about the characteristics of the epidermis, and this machine-learning algorithm is giving us a much more comprehensive picture, he said. We can extract a lot more potential data on traits from the images weve taken. This is something people could not have done before.

Leakey is an affiliate of the Carl R. Woese Institute for Genomic Biology at the U. of I. He and his colleagues report their findings in a study published in The Journal of Experimental Botany and in three papers in the journal Plant Physiology (see below).

The National Science Foundation Plant Genome Research Program, the Advanced Research Projects Agency-Energy, the Department of Energy Biosystems Design Program, the Foundation for Food and Agriculture Research Graduate Student Fellows Program, The Agriculture and Food Research Initiative from the U.S. Department of Agriculture National Institute of Food and Agriculture, and the U. of I. Center for Digital Agriculture supported this research.

Read more here:
New imaging, machine-learning methods speed effort to reduce crops' need for water - University of Illinois News

Physiology

Neurological manifestations of COVID-19 in patients: from path physiology to therapy – DocWire News

This article was originally published here

Neurol Sci. 2021 Aug 21. doi: 10.1007/s10072-021-05505-7. Online ahead of print.

ABSTRACT

Coronavirus is a family of ARN positive single-stranded belonging to the family of Coronaviridae. There are several families of coronavirus that transmit more or less serious diseases. However, the so-called coronavirus-19 (SARS-CoV2) is the one that is currently causing most of the problems; in fact, biological dysfunctions that this virus causes provoke damage in various organs, from the lung to the heart, the kidney, the circulatory system, and even the brain. The neurological manifestations caused by viral infection, as well as the hypercoagulopathy and systemic inflammation, have been reported in several studies. In this review, we update the neurological mechanisms by which coronavirus-19 causes neurological manifestation in patients such as encephalomyelitis, Guillain-Barr syndrome, lacunars infarcts, neuropsychiatry disorders such as anxiety and depression, and vascular alterations. This review explains (a) the possible pathways by which coronavirus-19 can induce the different neurological manifestations, (b) the strategies used by the virus to cross the barrier system, (c) how the immune system responds to the infection, and (d) the treatment than can be administered to the COVID-19 patients.

PMID:34417704 | DOI:10.1007/s10072-021-05505-7

Read more from the original source:
Neurological manifestations of COVID-19 in patients: from path physiology to therapy - DocWire News