Biomedical Engineering News

Last month, cardiac researchers at the University of Cincinnati discovered a unique gene associated with heart disease and diabetes. This gene, the HDAC9, was shown to prevent the effects of obesity (e.g. high blood sugar, cholesterol, and fatty liver disease) when deleted from mice being fed high fat diets.

The HDAC9 gene codes for the enzyme Histone Deacetylase 9, which belongs to a class of enzymes responsible for controlling DNA expression. Removing this enzyme from the cellular atmosphere affects the gene expression profile of the cell in a way that, according to Dr. Chatterjee, “prevent[s] mice from developing obesity-related diseases during chronic high-fat feeding.”

Typically, an increase in caloric intake is supposed to decrease the expression of HDAC9 gene, which is supposed to prime fat cells for efficient storage of fat content. However, chronic over-feeding leads to an increase in the expression of HDAC9 in fat cells, leading to a host of obesity-related symptoms and diseases (such as high blood sugar, high blood pressure, fatty liver disease, and heart disease).

With the above knowledge, however, scientists can now look to create drugs that target and decrease the expression of HDAC9, so that like the mice in Dr. Chatterjee’s study, obesity-related symptoms and diseases can be mitigated in humans who may be suffering from such conditions.

Differential equations, or equations involving the rate of change of variable(s), are useful in modelling many natural phenomena. Population growth, for example, can be modeled quite simply using differential equations given that we accept the following premises:

• The rate of change of a population is proportional to the current population (since more people mean more kids (gross)).
• All populations eventually hit a maximum (a point where they can no longer grow (since the environment can only carry so many people)).

If we accept these two premises, then population growth can be modeled as shown in the interactive plot below (move the sliders around to see how the plot changes) where:

• p represents the initial population (expressed as a percent of the maximum population).
• r represents the intrinsic growth rate of the population (i.e. how much this population wants to have kids).

• The y-axes represents the population (as a percent of the maximum population).
• The x-axes represents time.

To understand how this model was developed, let us express our two assumptions about population growth (given at the top of this article) mathematically:

• The rate of change of a population () is proportional to the current population (): (meaning is proportional to by , the intrinsic growth rate).
• All populations eventually hit a maximum (a point where they can no longer grow): so when since means the population has reached it’s max.

Putting these two assumptions together, we get: which is a differential equation known as the logistic equation. When we plug into the logistic equation we get or that the population no longer changes (since we hit the max of ).

The logistic equation can be interpreted as saying that the rate at which a population changes is proportional to an intrinsic growth rate, the current population, and how far the current population is form the maximum population (since the further we are from the maximum population, the less the environment/resources constrain us in terms of population growth).

The solution to the logistic equation (which involves solving for and getting rid of (and also a lot of calculus)) is what has been plotted in the interactive plot above.

Although in the real world there are many other factors at play, the above model is nonetheless insightful and serves as the basis for more complex population models. For more information, click here.

Aerobic exercise, or walking in specific, may be the single most beneficial thing you can do to improve your health. In fact, you don’t even have to spend much time walking or exercising, just 30 minutes a day will do. According to Dr. Mike Evans, the health benefits of walking or mildly intense aerobic exercise are numerous, and can lead to drastic improvements in many health parameters:

The trick is to actually commit to 30 mins of walking or aerobic exercise per day. Many people looking to improve their health start out strong but lose motivation afterwards. As Google Trends data (below) clearly indicates, the search term “exercise” reaches a peak in early January after which it slowly falls off. This is presumably due to New Year’s resolutions to lose weight, which most people initially adhere to but later get side-tracked from.

Thus, to reap the health benefits of walking or aerobic exercise, committing 30 minutes a day (consistently and over the long haul) is key.

For those seeking an easy, healthy, flavorful snack to supplement their daily diet, popcorn should be on the list.

Researchers at the University of Scranton in Pennsylvania have determined that popcorn actually contains higher levels (up to 300 mg per serving) of the antioxidant polyphenol than comparable fresh fruits and vegetables. Polyphenols assist in removing harmful free oxygen radicals from the cellular environment. Free oxygen radicals are highly reactive compounds that can cause cellular death and increase the risk of cancer. They also cause signs of aging such as wrinkles. By following a diet high in antioxidants, the body can better regulate free radical levels within the cells.

Additionally, popcorn (considered an unprocessed whole grain) contains high levels of dietary fiber important for gastrointestinal health. The hull of the popped kernel was determined to be of the highest nutritional value.

It should be noted, however, that all the health benefits of popcorn are derived from the corn itself, and not from any additional flavorings like butter or salt. Ideally, a popcorn snack should consist of air popped corn with no oils or salt. If this is too flavorless, try popping your own corn in oil. Home made oil popped corn contains about half the fat as microwave popcorn bags, and is cheaper. Properly prepared, popcorn can be one of the healthiest snack foods available.

The thirst response doesn’t engage until the body has lost 1-2% of its total water volume. Mild dehydration, however, can potentially set in before the thirst response (at a loss of around 1.5% of total water volume). Hence the timeless advice: drink before you’re thirsty.

But does dehydration really impact behavior? Researchers at the University of Connecticut Human Performance Lab decided to pursue the question. They assigned a set of tasks to a group of students who were well hydrated, and then assigned the same tasks to the same students while dehydrated. The tasks were designed to test the participants cognitive skills, including memory, reaction time, concentration, and reasoning.

The women in the study showed little cognitive difference when dehydrated, though they did complain of headache, fatigue and lack of concentration. The male participants, on the other hand, experienced fewer physical symptoms, but experienced difficulty in memory and concentration based tasks. It is unclear why this difference exists, but the dehydration response is considered a survival mechanism designed to protect people from dangerous levels of dehydration.

Staying well hydrated is the key to elevated energy levels and productivity. Experts agree you should consume two liters of water per day to prevent the symptoms of dehydration. Starting your morning with a large glass of water is a good way to get a jump-start on the day, and keeping a water bottle can help with hydration throughout the rest of the day.

Researchers at the University of California Irvine have compiled the world’s first “metabolome” or full liver metabolite profile in their study on how the body’s circadian rhythm affects different signaling proteins and physiological factors. Director of the UC Irvine Center for Epigenetics & Metabolism Paolo Sassone-Corsi describes the findings as a sort of symphony conducted by the main circadian gene: CLOCK.

“Metabolites and signaling proteins – like the horns and strings in an orchestra – need to be perfectly coordinated, and we’ve found that CLOCK provides that direction.”

Production of the basic amino acids, carbohydrates, and lipids and other biological health processes have been shown to be greatly controlled by the body’s internal clock. According to their article published in this week’s early edition of the Proceedings of the National Academy of Sciences, over 600 liver-borne metabolites were identified, 60% of which were shown to be dependent on circadian cycles.

The massive array of interdependent relationships illuminated by the findings may lead to new ways of understanding nutrition, metabolic diseases, aging, and perhaps even the ways medicine is formulated and administered. To put the metabolome to use, the researchers have founded CircadiOmics, a web-based database that profiles the metabolites, and their genetic and network interactions.

“Within CircadiOmics, we were able to integrate this circadian metabolite data with multiple other sources to generate the first comprehensive map of the liver metabolome and its circadian oscillations and develop regulatory hypotheses that have been confirmed in the laboratory,” said director of UCI’s Institute for Genomics & Bioinformatics, Pierre Baldi. “CircadiOmics is being expanded with metabolic data about other tissues and conditions and will be invaluable to further our understanding of the interplay between metabolism and circadian rhythms in healthy and diseased states.”