Global Temperatures Continue to Rise

The last two years have been the hottest two years ever recorded, according to scientists at the National Aeronautic and Space Administration (NASA). The hottest year was 2016, followed closely by 2017. In fact, the five hottest years ever recorded going all the way back to 1880 (when it first became possible to measure global temperatures with any accuracy) have all been since 2010.

Climate deniers are beginning to look a bit foolish, don't you think? But they can still argue that we don't really know what is causing global temperatures to rise (translation; there's insufficient evidence that global warming is being caused by human activities), and to use that argument as an excuse for not doing anything about it.

They win that argument at their own peril, in my view. By the time we all agree on what is causing global warming and what should be done to mitigate it, it may be too late - the climate will be changed for perhaps hundreds of years, if not permanently. Humans will have to adapt to very different climate conditions than exist today. Lucky me, I won't live long enough to see it.

Development of Antibiotic Resistance in the Natural Environment

A report from the United Nations Environmental Program offers a useful summary of how the presence of low concentrations of antibiotics in the environment can lead to bacterial antibiotic resistance.

According to the report, antibiotics make it into the natural ecosystem in three ways; 1) via improper disposal of unused prescriptions of antibiotics, 2) through the inadequate treatment of wastewater, and 3) in agricultural waste as a result of the heavy use of antibiotics in farm animals. The report suggests that these low concentrations of antibiotics contribute to antibiotic resistance. In other words, it's not just the over-prescribing of antibiotics for humans that leads to antibiotic resistance; it's also a slow, ongoing process as a result of current environmental contamination. In addition, we know very little about how certain other substances in the environment, such as heavy metals, further contribute to antibiotic resistance.

If the report is correct, we may need to pay more attention to sewage and wastewater treatment, as well as working toward curbing the over-prescribing of antibiotics for farm animals, as well as for humans.

The report contains a handy visual flow chart (p. 15) that teachers might use to explain this subject to students.

You and Your Microbiome

Two recent findings on different subjects highlight the importance of the community of bacteria in our gut, called our microbiome.

First up is an article detailing the effects of exercise on our microbiomes. Researchers at the University of Illinois Urbana-Champaign showed that a few weeks of moderate exercise by people who were not exercising previously alters the number and types of bacteria found in their guts. And although the types of bacteria were not the same in everyone, in general there were increases in the types of bacteria that reduce inflammation, fight insulin resistance, and enhance metabolism. The changes were not permanent, however; the bacterial community reverted back to the original state when the subjects quit exercising. The authors speculate that some of the benefits of exercise may be due to the effects of exercise on our biomes. A New York Times article discusses this topic in some depth.

On an entirely different subject, scientists may have discovered at least part of the explanation for why dietary fiber is good for you. It turns out that although we humans can't digest dietary fiber, some of the bacteria in our gut can. It's their major food supply! More dietary fiber means more bacteria, some of which reward us by supplying us with certain nutrients that we can use. In addition, bacteria signal the cells lining the gut to produce more mucus. A thick mucus coat on the inner surface of the gut is important; it protects the gut cells from damage and prevents the immune system from overreacting to the presence of so many bacteria. A more detailed explanation of this subject can be found here, for those who are interested.

Life Expectancy in the U.S. Continues to Decline

Life expectancy in the U.S. has fallen for the second year in a row, according to the CDC. 

Back in 2015 the World Health Organization (WHO) ranked the U.S. 31st out of 183 countries in terms of life expectancy; right between Cuba and Costa Rica.  And then things began to go downhill.  In 2015, life expectancy in the U.S. fell for the first time in a long time (see this blog, Dec. 9, 2016), and now the CDC reports that it has fallen again in 2016, the latest year for which there are complete data.

Although we can argue about whether or not two years in a row is the beginning of a long-term trend, surely this is not a good sign.  Developed and developing countries generally report increases in longevity nearly every year, reflecting better health care, more stringent safety standards, better environmental conditions, fewer wars, and so on.  That's what the U.S. did, at least until two years ago.

Among the top ten causes of death each year, three stand out as largely responsible for increased death rates over the past two years, according to a CNN report: unintentional injuries, Alzheimer's disease, and suicides.  Unintentional injuries include accidental drug overdose deaths, of which there were 63,000 in 2016!  The "war on drugs" isn't working, it seems.

Does a Frozen Embryo Have an Expiration Date?

How long can a frozen embryo be stored before it is implanted into its potential mother? Does a frozen embryo have an effective "use by" date, like most foods?

Recent evidence suggests that frozen embryos could be stored almost indefinitely, it seems. Case in point: a 25-year old woman recently gave birth to a child after receiving an embryo that was conceived and frozen 25 years ago. In other words, the embryo was conceived and frozen in the same year that its birth mother was born!

There are no official databases of when embryos are frozen and subsequently used, and so there's no way of knowing if this is a record of some sort. The couple chose the embryo after reviewing its biological parents' profiles, because they were interested in a child that would look somewhat like themselves. Only later were they made aware of the embryo's age. The embryo came from a faith-based fertility clinic that focuses on saving, not destroying, embryos.

Reproductive scientists are not surprised that embryos remain viable after long-term storage, although there have been no scientific studies carried out to find that out. The available evidence suggests that embryos are at the greatest risk of damage by the thawing procedure, and not by the length of frozen storage.

Redefining High Blood Pressure is a Two-Edged Sword

Two months ago I highlighted the new American Heart Association guidelines for defining high blood pressure. I was a bit skeptical, as you may have noticed (see this blog Nov. 14, 2017).

A recent opinion piece by Aaron Carroll, a professor of pediatrics at Indiana University School of Medicine, does a better job than I of pointing out that while keeping blood pressure under control is important, the new guidelines could easily lead to over-treatment of patients who might not actually need treatment. That's because the new guidelines are based on a study of people who were at high risk of cardiovascular disease, either by virtue of their age or because they had another underlying cardiovascular or kidney condition. So technically, the new guidelines may not apply to people whose only symptom is high blood pressure. But will patients and their doctors be aware of that? In addition, some people whose blood pressures are usually normal have slightly elevated blood pressures when they are under the stress of being in a doctor's office - its called "white-coat hypertension".

Thank you, professor Carroll, for your thoughts on this issue.