metabolism Archives - Iran News Daily

Studies Say Timing of Meals Affects Body Rhythms, Metabolism

reporter 1222 — Sat, 01 Aug 2020 07:35:45 +0000

TEHRAN (Iran News) – A new research shows the way that cells in the body interact with each other during their own 24-hour clock and how it plays a critical role in the health of a person’s metabolism.

It’s widely reported that shift workers suffer from high rates of obesity and diabetes when their internal clocks do not coordinate with each other, as well as due to irregular eating times. However, little is known about the interaction between internal clocks and eating schedules, and specifically, the impact on overall health, MedicaXpress reported.

Now, in a new study published in Science, a team of researchers led by Mitchell Lazar, MD, Ph.D., the Willard, and Rhoda Ware, Professor in Diabetes and Metabolic Diseases and director of Penn’s Institute for Diabetes, Obesity, and Metabolism, sheds new light on the question.

“The internal clocks in the brain synchronize clocks in peripheral tissues, and misalignment of this system is associated with metabolic dysfunction,” said Lazar, the senior author of the study. “But how the environment and genetic factors control the clocks in peripheral tissue and whether communication exists between clocks in different cell types are largely unknown.”

Lazar’s team, led by postdoctoral fellow Dongyin Guan, Ph.D., established a new mouse model that can specifically disrupt the internal clock in hepatocytes, the major cell type in the liver, which is the body’s metabolic hub. As a result of this disruption, researchers observed an accumulation of triglycerides in the blood that increase the risk of heart disease, diabetes, and stroke. These results indicate the importance of the internal clocks in peripheral tissue of the liver in maintaining metabolic homeostasis.

Surprisingly, the metabolism of other cell types in the liver was also reprogrammed when the internal clock of hepatocytes was disrupted.

“Our discovery of clock communication between different cell types is very exciting as it suggests a previously unappreciated way that the body’s rhythms are coordinated,” said Guan.

Although day/night cycles influence behavioral rhythms, such as sleeping, emerging evidence suggests that food consumption is an important factor in synchronizing peripheral clocks. Recent research showed time-restricted eating can benefit metabolism, and many dieters try intermittent fasting to lose weight. The Lazar team observed that both food timing and the integrity of the internal clock in the liver altered rhythms of metabolism. Specifically, they showed that nearly half of rhythmic genes are regulated by both the internal clock and when the mice ate their food.

Lazar is hopeful that a better understanding of how food affects the body’s internal rhythms could lead to an optimized diet schedule, which could be an important preventive approach for shift workers as well as a potential therapeutic strategy for patients with metabolic disorders such as obesity and diabetes.

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Body temperature of 21st century man

reporter 1222 — Mon, 13 Jan 2020 10:30:21 +0000

A recent analysis of temperature trends suggested that the average human body temperature has dropped since the 19th century due to physiological changes. The authors of the new study also highlighted the potential causes of these alterations.

Most of us only take our temperatures when we are worried that we have a fever, as a result of an infection or a cold, for example, Iran News quotes what medicalnewstoday.com reported.

But body temperature can indicate and be influenced by many other factors; lifestyle habits, age, and ambient temperature can all influence how our body disperses heat.

Body temperature is also a marker of metabolic health. Specifically, the authors of the new study explained, human body temperature indicates the metabolic rate, which some have linked with longevity and body size.

So what is our normal body temperature? In 1851, a German physician called Carl Reinhold August Wunderlich surveyed 25,000 people in one city and established that 37°C is the standard temperature of the human body.

However, recent analyses and surveys suggest that the average body temperature is now lower.

For instance, a study of more than 35,000 people in the United Kingdom and nearly 250,000 temperature measurements found that 36.6°C is the average oral temperature. Could this discrepancy be a result of changes in measurement tools? Or, do the new findings reflect higher life expectancy and better overall health?

Myroslava Protsiv, then at Stanford University’s Division of Infectious Diseases and Geographic Medicine, in California, and colleagues set out to investigate.

The team hypothesized that “the differences observed in temperature between the 19th century and today are real and that the change over time provides important physiologic clues to alterations in human health and longevity since the Industrial Revolution.”

To test their hypothesis, the researchers analyzed information from three datasets:

The first included data from 1862–1930 obtained from Union Army veterans of the Civil War.

The second dataset was from the United States National Health and Nutrition Examination Survey I, which took place from 1971–1975.

The third dataset was from the Stanford Translational Research Integrated Database Environment, which contains data from people who received healthcare through Stanford between 2007 and 2017.

Overall, the scientists had access to 677,423 temperature measurements, which they integrated, forming a model of change over time.

Some of the researchers’ findings include:

● The body temperature of men today is, on average, 0.59°C lower than that of men born in the early 19th century.

● Similarly, women’s body temperature dropped by 0.32°C from the 1890s to today.

● Overall, the analysis found a 0.03°C decrease in average temperature with every decade.

To check whether the decreases stemmed from advances in thermometer technology, Protsiv and the team looked at changes within datasets, assuming that doctors in each historical period were generally using the same types of thermometers.

The results of the analysis within datasets reflected the changes in the combined data. “Our temperature’s not what people think it is,” said Dr. Julie Parsonnet, a professor of medicine, health research, and policy, and the senior author of the study.

However, because gender, time of day, and age can each change our body temperature, the researchers do not advise updating the standard for all US adults.

What has caused our temperature to drop?

So why has the average body temperature changed? “Physiologically, we’re just different from what we were in the past,” Parsonnet said.

“The environment that we’re living in has changed, including the temperature in our homes, our contact with microorganisms, and the food that we have access to.”

“All these things mean that, although we think of human beings as if we’re monomorphic and have been the same for all of human evolution, we’re not the same. We’re actually changing physiologically.”

Furthermore, Parsonnet believes, the average metabolic rate, which indicates how much energy our bodies use, has declined over time. This decrease could result from a decrease in inflammation.

“Inflammation produces all sorts of proteins and cytokines that rev up your metabolism and raise your temperature,” she said.

Finally, air conditioning and heating have resulted in a more consistent ambient temperature, making it unnecessary to expend energy to maintain the same body temperature.

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Hormone from Fat Boosts Metabolism in Both Exercise & Cold

reporter 1222 — Thu, 03 May 2018 07:55:17 +0000

Researchers have uncovered a new kind of clue to an individual’s variable response to exercise — a hormone whose levels in the bloodstream rise sharply in exercise as well as in cold.

Sad but true, we don’t all respond equally to exercise. Researchers at Joslin Diabetes Center have uncovered a new kind of clue to this variable response — a hormone whose levels in the bloodstream rise sharply in exercise as well as in cold.

The finding came from the first comprehensive study of fat-controlling hormones (known as lipokines) in exercise. “This is a whole new area in research on exercise metabolism, and we seem to have found another mechanism by which exercise can have beneficial effects,” says Laurie Goodyear, Ph.D., Head of Joslin’s Section on Integrative Physiology and Metabolism and senior author on a report on the work published in Cell Metabolism.

Experiments in both humans and mice have shown that levels of one lipokine, with the unwieldy name of 12,13-diHOME, climb significantly in exercise, unlike the levels of other lipokines analyzed.

The study followed up on research published last year in joint work with the lab of Joslin’s Yu-Hua Tseng, Ph.D. This collaboration explored the release of lipokines from brown fat, which can burn energy in people or other mammals exposed to cold. In both humans and mice, the researchers demonstrated that the 12,13-diHome molecule was released from brown fat during cold exposure and offered beneficial metabolic effects.

“We found it very striking that when we then analyzed lipokines in exercise, the same lipokine that increased with cold also increased with exercise,” says Goodyear, an Associate Professor in Medicine at Harvard Medical School.

The Joslin researchers began by measuring levels of lipokines before exercise, immediately after exercise and three hours after exercise in the blood of 27 healthy male volunteers of various ages. When measured immediately after exercise, “12,13-diHOME really stood out quite dramatically,” says Goodyear. The scientists followed up by studying another set of volunteers, 12 healthy young people (split evenly between women and men) without regular exercise routines. Again, levels of the lipokine generally climbed substantially during exercise. Additionally, the scientists found that, in general, the more fit people were, the greater their resting levels of 12,13-diHOME.

The team next studied lipokines in exercising mice and saw similar results. “When mice do a single bout of exercise, we see an increase in 12,13-diHOME,” Goodyear says. “We also saw an increase after exercise training.”

Next, the investigators looked at molecular clues to the source of the lipokine and discovered that brown fat was a likely suspect. This was confirmed when the scientists removed most brown fat from mice and found that 12,13-diHOME levels in exercise dropped sharply. “It seems to be the first example of a hormone released from brown fat that might regulate some of the metabolic effects of exercise,” Goodyear notes.

Researchers around the world look for ways to increase energy expenditure, and thus reduce obesity, by boosting brown fact activity. “Most of our data suggests that exercise doesn’t ramp up the energy expenditure of brown fat, but here, exercise is clearly having an effect on brown fat,” she says.

Further work in both mice and mice muscle cells that were given 12,13-diHOME revealed that the lipokine acts as a signal to boost the use of fatty acids as fuels, Goodyear adds.

She and her colleagues are broadening and deepening their research on the role of the lipokine, and other lipokines that decrease during exercise, in larger human cohorts as well as in further animal studies. “The more knowledge we have about exercise and how it works, the better we can understand how to combat metabolic disease,” she says.

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