Tuesday, July 28, 2015

An Inhalable Vaccine Against Ebola?

A recent research study published in the Journal of Clinical Investigation offers hope that a vaccine against the Ebola virus (and perhaps other infectious diseases) can be delivered as an aerosol spray rather than injected. In the study, monkeys were given either an aerosolized vaccine against Ebola via the respiratory tract; the same vaccine in injected liquid form; or no vaccine at all. Four weeks later, all of the monkeys were deliberately exposed to the Ebola virus to see what would happen. The non-vaccinated monkeys died, whereas all of the treated monkeys survived.

At the end of the experiment the vaccinated animals were euthanized and blood and tissue samples were taken for analysis. Antibody titers against the Ebola virus were high in all of the vaccinated animals regardless of route of vaccine delivery, and there were no signs of the Ebola virus. But in addition, the animals that had received the aerosolized vaccine had developed an especially vigorous immune cell response in the lungs. This latter finding is important, because the Ebola virus may infect some of its victims via droplets of aerosolized fluids that enter the lungs. The finding of an enhanced immune cell response in the lungs suggests that an aerosolized vaccine might offer an extra level of protection against Ebola.

But perhaps the biggest advantage of an aerosolized vaccine is that it could be delivered without the assistance of medical personnel. This would be a huge advantage in places such as West Africa (where the recent outbreak of Ebola occurred) because medical personnel are scarce in that region.

An aerosolized vaccine against Ebola has never been tried in humans. Clinical trials in humans will be needed before such a vaccine would become widely available.

Tuesday, July 21, 2015

Replacing a Heart Valve Without Major Surgery

Replacing a failing aortic heart valve is actually pretty routine. However, the normal procedure requires cracking the chest, stopping the heart, and cutting into the heart to get to the damaged valve. Because of the traumatic nature of the surgery itself, full recovery is more likely if the patient is relatively young and healthy except for the needed valve. As a result, the surgery is not recommended for patients over about 80 years of age.

Now those older patients have a viable option. Federal regulators recently approved a new technique called TAVR (transcatheter aortic valve replacement) for replacing aortic heart valves in patients who are deemed at high risk from open-heart surgery. In TAVR, surgeons attach a folded-up artificial valve to a catheter, insert it into a main artery and thread it up to the heart, and then open it like an umbrella. The catheter lodges in place, pushing the old damaged valve out of the way. The procedure can be done in minutes with the patient awake and only lightly sedated. Recovery time is minimal.

The TAVR technique is likely to be a lifesaver for the estimated 100,000 patients who are too old or sick for open-heart surgery. One patient it has helped is former Secretary of State Henry Kissinger, age 92. Right now TAVR is only recommended for older and sicker patients because there are only 5 years of data on how long the new valves will last. But if you're 80 and need an aortic valve replacement just to get through the next year, do you really care whether the valve lasts 20-30 years?

Some surgeons think that TAVR will eventually replace open-heart surgery as the method of choice for younger patients as well. That will depend on how long valves replaced by the TAVR procedure last. It matters to someone who is closer to age 50 than 80.

Saturday, July 18, 2015

Producing Omega-3 Oils in GM Plants

Aside from tasting good, oily fish such as salmon are good for you because they contain special types of fish oils - called omega-3 oils - that are known to reduce the risk of heart disease by reducing the risk of atherosclerosis. However, salmon do not actually make the oils. Omega-3 oils are made by single-celled algae, which are eaten by small herbivorous fish, which are in turn eaten by small carnivorous fish and so on up the food chain. Eventually the omega-3 oils end up in the salmon.

The demand for wild-caught salmon is leading to a depletion of salmon stocks worldwide. An alternative choice food choice would be farmed salmon, raised in enclosed bays or in pens in the oceans. Increased consumption of farmed salmon could reduce the demand for wild-caught salmon and thus prevent wild salmon from being overfished. Unfortunately, farmed salmon contain lesser quantities of omega-3 oils unless they are fed a steady diet of small fish such as wild-caught anchovies. That leads to a problem; feeding farmed fish wild-caught fish to boost their omega-3 content may just lead to overfishing of those other smaller species. And from the fish farmer's point of view, feeding farmed salmon a diet of wild-caught fish is expensive.

A solution may be on the horizon, but not everyone is going to like it because it involves genetic engineering and the creation of genetically modified organisms (GMOs). A team of scientists in England has managed to genetically modify an oil-producing plant related to rape (the plant that produces canola oil) so that it produces high yields of omega-3 oils. The new GM plant contains genes from several other plant species, including a moss and an alga. It produces enough omega-3 oils that farmed salmon could be raised on a diet of GM fish chow.

So here's the dilemma; do we want to raise farmed salmon on GM chow, producing a healthy food alternative to wild salmon and reducing the fishing pressure on wild salmon populations? Or do we want to continue to shun GMOs and deplete the world's oceans of fish?

Sometimes our choices are not all that easy.

Monday, July 13, 2015

The FDA Bans Trans Fats

Last month the U.S. Food and Drug Administration (FDA) issued a ruling that will effectively ban artificial trans fats from processed foods. The agency estimates that the move will reduce the incidence of coronary heart disease and reduce the number of heart attacks per year.

Artificial trans fats are created when vegetable oils are partially hydrogenated to create a butter-like solid. They became popular in the 1940s and '50s because they improve the texture, taste, and shelf life of processed foods and because they are cheaper than butter. However, we now know that trans fats contribute to the risk for coronary artery disease, just as the saturated fats in butter and animal fat do. The use of trans fats for deep-frying was banned some time ago, and most processed food products have already phased trans fats out. The current ruling will end the use of trans fats altogether in three years. The three-year phase-out period is to give processed foods manufacturers time to reformulate their recipes and modify their manufacturing processes accordingly.

There are small amounts of natural trans fats in beef, lamb, and full-fat dairy products such as butter and cream, but there's not much the FDA can do about that. The FDA ban only applies to trans fats added to processed foods, where the solution is to simply not use them as ingredients.

Wednesday, July 8, 2015

California Passes Strict Child Vaccination Law

It's been a hard-fought and closely watched battle in California. But in the end, proponents of mandatory childhood vaccinations chalked up a victory over opponents of vaccinations. Last week Governor Jerry Brown signed SB 277, a bill that eliminates personal and religious beliefs as valid reasons for not having one's child vaccinated in order to attend school. Unvaccinated children can still be home-schooled of course, and the law still allows for medical exemptions for those few children who have a verifiable medical excuse for not being able to be vaccinated. But for all others, vaccinations will now be required to attend public schools.

As it moved through the legislative process, SB 277 was modified a bit from its original form in order to make it palatable to more legislators and ensure its passage. In the final approved version, children who were not vaccinated in kindergarten will not have to be vaccinated until the 7th grade, and 10th-graders who are not currently vaccinated will never need to be vaccinated. In other words, the full effect of the new law will be phased in over several years.

California joins just two other states (West Virginia and Mississippi) that currently do not allow exemptions from childhood vaccinations for either religious or personal beliefs. Currently, 47 states allow exemptions because of religious beliefs, and 20 states allow exemptions for personal, moral, or other reasons. However, a number of states are planning to make changes to their current laws. To view the situation in your state and to find out what legislative changes might be planned or in process, visit the page on that topic on the website of the National Conference of State Legislatures.

Thursday, July 2, 2015

A Libido Pill for Women?

Move over, Viagra and Cialis. Women are about to get a sexual satisfaction pill of their own. The only thing is, does it work?

Flibanserin is not a hormone-type drug; it is a neuromodulator that alters certain neurotransmitter pathways in the brain. Specifically, it is a 5-hydroxytryptamine receptor agonist/antagonist. The FDA twice rejected the manufacturer's application for approval, but now seems poised to approve it to treat two little known disorders in women; hypoactive sexual desire disorder (HSDD) and female sexual interest/arousal disorder (FSIAD).

Supposedly, Flibanserin affects a woman's sense of pleasure during sex, but a close reading of the FDA report on effectiveness is not very encouraging. In the study, half of the women received Flibanserin and the other half received a placebo. Women receiving Flibanserin reported just 0.5 to 1 more "satisfying sexual events" per month than the placebo group, from a baseline of 2-3 per month. Will that be enough for women to want to use this pill?

If Flibanserin is approved, the marketing campaign will probably focus on convincing women and their doctors that HSDD and FSIAD are far more prevalent than we think. At least, that has been the pattern with Viagra and Cialis for the treatment of erectile dysfunction (ED) in men. The latest pitch I heard is that half of all men over 40 suffer from some symptoms of ED. That sounds like a stretch....

You can read the entire 136-page FDA briefing document on Flibanserin here.

Wednesday, June 24, 2015

Neanderthals Interbred with Modern Humans

What happened to the Neanderthals, that now-extinct group of stocky, big-boned ancient humans who lived in Europe and Asia until about 30,000 years ago? Were they wiped out by conflict with modern humans who arrived later in Europe or by some other unfavorable environmental condition? Did they interbreed with modern humans, ultimately "disappearing" as a distinct group because their genes were incorporated into a much larger gene pool of modern humans?

Several years ago I reported (this blog May 12, 2010) that Neanderthals shared a number of genetic variations with modern Europeans that they did not share with modern Africans. These findings at least suggested, but did not prove, that interbreeding occurred when Neanderthals met modern humans.

More recently, DNA analysis reveals that up to 3% of the DNA of modern Eurasians is similar to the DNA of the Neanderthals. And according to a paper published this week in Nature, DNA analysis of a bone of a modern human who lived in present-day Romania around 40,000 years ago revealed that 6-9% of his genes were from Neanderthals. In other words, he may have had a great, great-grandparent who was a Neanderthal.

Of course, this does not prove that interbreeding was the cause of the disappearance of the Neanderthals. Interbreeding can occur between groups in conflict, as the behavior of modern-day humans clearly shows. But at least it indicates that interbreeding did occur, at least occasionally.