Sunday, December 20, 2015

Historic Climate Change Deal Signed

At a historic meeting in Paris this month, 195 nations have finally agreed on a deal to try to curb worldwide emissions of greenhouse gases in an effort to slow the rate of climate change. Although the specifics of the deal are not entirely spelled out, a core requirement of the deal is that every country must do something, and that their goals must be clearly spelled out and made public. The deal is at least recognition for the need to make progress. The countries will reconvene every five years to review their individual and collective progress and to update their plans.

Not everyone is entirely happy with the deal, of course. Poor countries want money to help them cope with the costs, and even some leeway (in terms of greenhouse gas creation) to catch up economically with rich countries, which they say have caused most of the global warming so far. And many people in the U.S. still question the science of climate change and/or the need for action, because any action taken will almost certainly have a high economic cost.

The winners will be innovators in new technologies such as solar and wind power, battery and energy storage technology, electric cars, energy efficiencies in the home and industry, and so on. Losers are likely to be the coal industry, and to a lesser extent oil and gas. But any shifts in fortunes are likely to take place over decades, not months or years.

Expect to hear more about what the U.S. pledges to do, and to experience the effects, in the coming years.

Thursday, December 17, 2015

Gut Bacteria Can Alter Energy Efficiency

Why do some people seem to stay thin no matter what they eat, whereas others struggle with obesity despite trying to limit their caloric intake? One factor is genetics; you're stuck with the genes and hence (at least in general terms), the same body type and energy metabolism that you inherited from your parents. Another factor, it seems, is the bacteria in your gut.

A key experiment showing the role of gut bacteria in nutrient absorption was published several years ago (see this blog, Sept. 11, 2013). The authors of the study wondered why twins sometimes were discordant for obesity (showed different tendencies toward obesity), and they suspected that gut bacteria were involved. To find out, they took samples of the gut bacteria from twins discordant for obesity, and gave those samples to mice. Lo and behold, the mice that received bacteria from an obese twin gained more weight than mice given bacteria from the non-obese twin.

Experiments published recently in Cell take the gut bacteria affect energy efficiency hypothesis one step further. In these experiments, researchers exposed mice to either a normal temperature environment (22 degrees Centigrade) or a cold environment (6 degrees C). Both groups were fed exactly the same number of calories per day. As expected, the mice in the cold environment initially lost weight as they burned fat to stay warm. But then something interesting happened; they began to gain weight again. When researchers examined the feces of both groups, they found that the cold mice had become 50% more efficient at absorbing nutrients from their food. Further examination revealed that the cold mice lacked a particular strain of gut bacteria. When mice in a normal temperature environment were given those bacteria, they gained weight.

Bottom line; it's possible that your ability to gain or lose weight may be influenced by gut bacteria. Although I pooh-poohed the idea back in 2013, there may just be the possibility that in the future, modifying your gut biome might actually become an effective dieting tool. We'll see; more research is needed.

Sunday, December 13, 2015

Increased Mortality Among Middle-Aged Whites

Mortality rates for most age- and racial-groups have declined over the past several decades. But among middle-aged whites, the mortality rate has actually increased. No other rich country has shown such a trend. Among poorly-educated white non-Hispanic Americans between the ages of 45 and 54, for example, mortality rate increased more than 10% between 1999 and 2013.

The culprit, it appears, is not one or more of the chronic diseases usually associated with more developed countries, such as obesity, diabetes, heart disease, stroke, and cancer. The main causes are suicides, and deaths due to drugs and alcohol, according to research published in the Proceedings of the National Academy of Sciences. These are generally signs of stress in a population, not consequences of affluence.

Although the mortality rate for middle-aged whites is the only mortality rate that is rising at the moment, it's still 40% lower than that for blacks. So perhaps we shouldn't make too much of this recent finding, except that it may tell us that in the future we'll have to focus on mental health and the sense of well-being for all racial groups, if we are to make any additional progress on mortality rates.

Wednesday, December 9, 2015

Survival Rates After a Cardiac Arrest

If you're going to experience a cardiac arrest (complete cessation of a heartbeat), it's best to do it in Seattle.

Cardiopulmonary resuscitation (CPR) always seems to work on the medical TV shows. But in truth, the chances of recovering from a cardiac arrest aren't all that good. Outside a hospital the average survival rate of patients eventually treated by an emergency medical service (EMS) is less than 10%; even in a hospital it's only about 20%. Survival rates vary considerably depending on where the patient undergoes a cardiac arrest. In Detroit the survival rate is only 3%; in Seattle it's 20%, according to an article in the New York Times.

The four components of CPR are chest compression, ventilation (breathing for the patient), defibrillation (shocking the heart to get it started again), and epinephrine. The first two can be done by amateurs (passers-by) and can be fairly effective as a stopgap measure if done right. The latter two require EMS staff. And the key to improved survival seems to be better education of amateurs and training and monitoring of EMS staff. Seattle, for example, has a long history of an emphasis on CPR awareness and education of amateurs, combined with continual training and monitoring of the success of EMS staff.

Keys to good CPR are that it should be done vigorously and for longer than most people think. If you ever are in a position to try to save a patient while waiting for the EMS, don't stop chest compressions for longer than 10 seconds at a time while searching for a pulse, and don't give up too soon. Cardiac compression can be tiring for the resuscitator, but an hour of compression rather than just 15 minutes can sometimes save a patient.

If you're not trained in CPR yet, you might consider taking a basic CPR training class. The Red Cross and the American Heart Association offer them on a regular basis.

Wednesday, December 2, 2015

An HIV-Preventing Drug Exists, But Isn't Being Used

Back in 2012, the FDA approved the first drug for the prevention of HIV infection in otherwise healthy persons who might be at risk for infection due to exposure to an infected partner. The drug, called Truvada, prevents HIV infections 92% of the time, meaning that it could sharply reduce the number of new HIV infections if it were widely used. That turns out to be a big "if", for hardly anyone seems to be using the drug.

The drug's manufacturer, Gilead Sciences, Inc., has made a lot of money ($1.8 billion in 2014) from the use of the drug to treat HIV-infected patients. But it has made no effort to market Truvada for use in healthy persons solely for the purpose of preventing HIV infection. The company says that it just isn't profitable to market the drug for HIV prevention. And as a result of a lack of marketing, many physicians and nurses are simply unaware that the drug has been approved and is available for HIV prevention. According to the Centers for Disease Control and Prevention (CDC), one in three primary care doctors and nurses have never even heard of the potential use of Truvada for what is called preexposure prophylaxis (PrEP).

Lesson learned: government health officials will have to take the greater role in educating primary care physicians and nurses about Truvada for PrEP. Health officials in New York are already doing so according to the CDC, and as a result the number of NY medicaid beneficiaries receiving PrEP more than quadrupled between 2014 and 2015.