Wednesday, February 22, 2017

First Vaping, Now "Dripping"

A study by researchers at Yale University reveals that about a quarter of all Connecticut teenagers who have tried vaping have circumvented e-cigarettes' design to deliver a stronger and more potent nicotine experience.  It's called "dripping"; instead of allowing the e-cigarette's wick to deliver a controlled amount of liquid to the cigarette's coils, the coil is exposed so that nicotine liquid can be dripped directly onto the hot coils, producing a much heavier nicotine vapor cloud.

Regulators aren't sure how to respond to this recent trend.  Although e-cigarettes certainly aren't as harmful as cigarettes, their long-term harm (if any) is still not known simply because they haven't been around long enough.  The concept of e-cigarettes has been around since the 1930s, but the first commercially successful product wasn't created until 2003.  For a complete timeline of the development and regulation of e-cigarettes, see this file.  I can't confirm or deny the accuracy of the timeline, but the file was compiled by a group called Consumer Advocates for Smoke-Free Alternatives Association, so please be aware of possible bias.

Wednesday, February 15, 2017

Gaining Ground on Clostridium difficile Infections

One of the most dangerous of all gut bacteria is a bacterium called Clostridium difficile.  C. difficile can cause diarrhea so severe that it can lead to death, especially in older patients in hospitals and nursing homes, in whom it is most common.  To make matters worse, it is difficult to treat because it is resistant to most antibiotics.  Although it is present in most people, its population is normally kept in check by the presence of other "good" bacteria, which tend to out-compete it.  But when nearly all of a person's gut bacteria are wiped out, for example when the person is given antibiotics, C. difficile can reproduce explosively, overwhelming the body's defenses.

Although C. difficile was first identified over 80 years ago, it wasn't until this century, when a strain of C. difficile developed resistance to most antibiotics, that the bacterium became a serious clinical problem.  In a 2015 study published in the New England Journal of Medicine, the Centers for Disease Control and Prevention (CDC) reported that in 2011, C. difficile infections caused about 15,000 deaths directly and contributed indirectly to another 14,000 deaths.

But now health officials are seeing signs that C. difficile infections may be on the decline.  One of the key factors may be our more enlightened use of antibiotics; i.e., only when truly needed.  By reducing the indiscriminate use of antibiotics, especially in hospitals and nursing homes, there have been fewer opportunities for C. difficile to gain a foothold.  But there are other signs of hope, too.  Several vaccines are in the works, and Merck has a new (and expensive) drug called Zinplava that is at partially effective at reducing recurrent infections.  Even fecal transplants (to reintroduce competing bacteria; see this blog, Feb. 23, 2014) seem to help, though these are still just in the experimental stage.

Progress is being made, though sometimes it seems slow.  All we can do is keep trying.

Saturday, February 11, 2017

Improving the Odds of Successful In Vitro Fertilization

During a normal monthly reproductive cycle, the endometrial lining of the uterus undergoes a series of changes that make it receptive to the possible arrival and successful implantation of an early-stage embryo.  Endometrial receptivity only lasts about 12 hours; under natural conditions it coincides with the time that the early-stage embryo would be expected to arrive at the uterus, if in fact an egg was fertilized that month.  It all just happens naturally, without any thought on our part.

For infertile couples who opt for in vitro fertilization (IVF) in an attempt to become pregnant, timing can be critical.  If the embryo is introduced into the uterus at a time when the uterus is not receptive, the whole process can end in failure.  An IVF procedure can cost tens of thousands of dollars, and its not unheard of for couples to try multiple times without success and without knowing why.  One possible reason for multiple failures is that the embryo may not have been introduced into the uterus at precisely the right time.  The 12-hour window of maximum receptivity can occur on different days of the cycle in different women, and in the past there was no way to determine it.

But now there's a test to determine the precise moment of maximum endometrial receptivity.  It's called the endometrial receptivity array (ERA) test.  The test works by analyzing the genetic expression of several hundred of the genes known to be involved in the buildup of the endometrium in preparation for implantation.  The period of maximum expression of these genes coincides with the best time for embryo implantation.  The test has dramatically improved the odds of a pregnancy for couples who had previously experienced multiple IVF failures.

Tuesday, February 7, 2017

An Experimental Alzheimer's Drug Fails in a Clinical Trial

A potentially promising drug for the prevention of Alzheimer's disease has failed in a key clinical trial, according to Eli Lilly, the drug's developer. In a study involving more than 2,000 patients with early signs of dementia, the drug, known as solanezumab, failed to prevent the advancement of the cognitive impairment that accompanies dementia and that leads ultimately to Alzheimer's disease.

The results were disappointing, but not all that surprising. So far, no drug has been able to prevent the progression of dementia once it has started. Researchers are reluctantly coming to the conclusion that by the time dementia first becomes apparent, it is already too late to affect the future course of Alzheimer's disease.

Whether solanezumab could prevent the development of dementia if it were given before the first signs of dementia is not known. Sadly, it may never be known. That's because it would be prohibitively expensive to conduct a drug study involving tens of thousands of seemingly normal people, in the hope of observing an effect on the few people among them that will ultimately develop dementia.

So we're at an impasse at the moment. There are several drugs on the market that can reduce (at least temporarily) the symptoms of the dementia associated with Alzheimer's disease, but there are no drugs that can prevent the slow progression of the disease. There aren't even any on the horizon, apparently. Don't expect progress any time soon.

Friday, February 3, 2017

Many Primate Species Face Extinction

Our closest living relatives in the animal kingdom, the primates, are in trouble. According to a comprehensive review of primate populations around the world by some 31 scientists from 11 countries, nearly 60% of all primate species are in danger of extinction, and many of the others are in decline. That includes every species of apes and nearly all species of lemurs. The one primate species that still appears to be doing extremely well is humans.

The causes are multiple and predictable. Reduction in habitat due to an expanding human population, changes in primate's habitat due to logging, agriculture, and mining, predation (hunting) by humans, and even climate change are all thought to be contributing factors.

Unfortunately, there aren't any easy solutions on the horizon. Unless action is taken soon, it becomes increasingly likely that some of our primate relatives will disappear from planet Earth, if not within the next few decades, most certainly within the next few centuries. And that would be sad.

Friday, January 27, 2017

New Guidelines for the Prevention of Peanut Allergy

An expert panel of scientists meeting under the sponsorship of the National Institute of Allergy and Infectious Diseases has issued new guidelines for the prevention of peanut allergies in young children. The guidelines draw on findings published last year (see this blog, Mar. 9, 2015) which showed that adding peanut proteins to the diet of young children at risk for developing allergies significantly reduced the chances of those children developing peanut allergies by age five. The new guidelines are that infants can be fed peanut-containing foods at any age; as early as they begin taking solid food, in fact.

Some parents are skeptical, and a few are even angry. That's because the previous guidelines were to withhold peanuts from young children in the hope that sensitivity to peanuts could be avoided. According to these parents, this reversal of the guidelines is just more evidence that scientists (and their recommendations) shouldn't be trusted.

But the reality is that we try to make rational choices based on whatever information we have at the time. So when new and better information becomes available (such as the data published last year), we should look carefully at it and change our view, if warranted. In a nutshell (no pun intended) that is what has happened with the peanut recommendations.

Tuesday, January 24, 2017

2016 was the Hottest Year on Record

2016 was the hottest year on record and the third consecutive year of record temperatures, according to climate scientists.   Furthermore, the rate of temperature change seems to be accelerating.

Nearly all climate models conclude that the most likely cause of global warming is rising levels of atmospheric CO2 levels brought about by the burning of fossil fuels.  And yet, so far not much has been done about it.  The problem (and perhaps the reason that climate deniers continue to deny that global warming is even happening) is that curbing future increases in CO2 will not be easy or cheap as long as we continue to depend on fossil fuels for most of our energy needs.

And so Earth will probably continue to warm up.  Sigh.