Be a good landlord.

Antibiotic-resistant superbugs are scary, but they are not the only negative, long-term consequence of our overuse of antibiotics. Dr. Martin Blaser of the Department of Medicine at NYU recently wrote commentary for Nature regarding the liberal use of antibiotics and its destructive impact on beneficial bacteria. Our gastrointestinal tracts provide habitat for a community of microorganisms that aid in digestion, produce vitamin K, and guard against harmful invaders. From an ecological perspective, these are mutualisms – relationships in which both organisms, the human and the bacterium, derive a benefit. This relationship should be protected. Instead, we cause irreparable damage the community of helpful bacteria with repeated courses of antibiotics. A therapeutic dose of amoxicillin may clear-up an ear infection, but not without collateral damage to these beneficial microbiota. Many people experience an upset stomach during a course of antibiotics. This is an indication that our helpful bacteria have been eliminated, but the results may go far beyond a tummy ache.

I spent some time in the Blaser Lab this summer where scientists and students were hard at work researching Helicobacter pylori. As Dr. Blaser explains in his essay, H. pylori was the dominant microbe in the stomachs of most people in the twentieth century. By the turn of the twenty-first century, however, fewer than 6% of children in the United States, Germany and Sweden were carrying the organism. H. pylori may have a bad rap for its connection to ulcers and stomach cancer, but its eradication has several surprising effects. For instance, people without the bacterium are more likely to develop asthma, hay fever, and skin allergies. Moreover, H. pylori helps regulate ghrelin and leptin, hormones that control appetite and metabolism, which may have implications in obesity. A dose of amoxicillin administered to treat a respiratory infection will also eliminate H. pylori in 20 – 50% of cases.

Farmers have noticed that repeated low doses of antibiotics cause animals to gain weight with less food. The Blaser lab has discovered that comparable sub-therapeutic doses cause changes in body fat and tissue composition in mice. Large doses, like those used to treat childhood infections, have similar results. Dr. Blaser goes on to emphasize the importance of age. The physiological changes that are triggered by antibiotic usage early in life are the hardest to reverse, yet the average child in the United States receives 10 – 20 courses of antibiotics before age 18.

To read more about threats to your friendly bacterial tenants and what we should do to protect them, read Dr. Blaser’s expert opinion in his essay for Nature.

A hurricane to Tip the scale.

Tonight New York City is bracing for Hurricane Irene, and while the storm will undoubtedly deliver aggressive winds and major flooding, the level of panic is a little excessive for a fading Category 1 hurricane. Don’t get me wrong, people should take all necessary precautions, and those New Yorkers in Zone A should certainly obey evacuation orders. As Governor Christy says “Get the hell off the beach,” you’ve maximized your tan. I just think that come Monday, people may feel a little bit silly for clearing out the grocery stores of every last crumb of bread and drop of milk.

Although the memory of Hurricane Katrina is still fresh (even more so for fans of Treme), New York City on Monday morning will still resemble New York City, not a post-Katrina New Orleans. Let’s get some perspective. Hurricanes, or tropical cyclones as they are known worldwide, are characterized by a region of extreme low pressure at the center that is surrounded by thunderstorms, causing powerful winds and heavy rain. The lower the pressure and the stronger the winds, the more intense the storm. The Saffir-Simpson Hurricane Scale only categorizes storms by wind speed, although central pressure is also a good indicator of hurricane strength.

Right now, Irene is hanging out about 100 miles south of Ocean City, Maryland. The average sustained wind speed is 80 mph, which makes it a Category 1 storm, and the pressure at the eye of the storm is 951 millibar. When the winds slow to 73 mph, it will become a tropical storm. When Hurricane Katrina hit New Orleans on August 29, 2005, it was a Category 3 storm with sustained winds of 125 mph and pressure of 920 millibar.

Katrina was the costliest tropical cyclone ever, with damage exceeding $100 billion. It also was one of the deadliest, claiming 1836 lives. But let’s talk about another storm. The most intense tropical cyclone ever was Typhoon Tip in 1979. Tip was positioned in the north western Pacific Ocean, and it made landfall on Guam and southern Japan. Although it didn’t claim as many lives as Katrina, the statistics are staggering. The highest sustained winds were 190 mph for one minute and 160 mph for ten minutes. The pressure at the eye of the storm reached an unheard of 870 millibar. It was also the largest storm ever, extending 1380 miles across, which is half the area of the continental United States. Typhoon Tip had such extreme winds, that it ranks as a hypothetical Category 6 on the Saffir-Simpson Scale. This means that the storm’s potential damage is beyond catastrophic.

Hurricane Irene may damage some roofs and fell trees, but we will emerge relatively unscathed. In comparison, read the description of a Category 5 hurricane below:

"People, livestock, and pets are at very high risk of injury or death from flying or falling debris, even if indoors in mobile homes or framed homes. Almost complete destruction of all mobile homes will occur, regardless of age or construction. A high percentage of frame homes will be destroyed, with total roof failure and wall collapse. Extensive damage to roof covers, windows, and doors will occur. Large amounts of windborne debris will be lofted into the air. Windborne debris damage will occur to nearly all unprotected windows and many protected windows. Significant damage to wood roof commercial buildings will occur due to loss of roof sheathing. Complete collapse of many older metal buildings can occur. Most unreinforced masonry walls will fail which can lead to the collapse of the buildings. A high percentage of industrial buildings and low-rise apartment buildings will be destroyed. Nearly all windows will be blown out of high-rise buildings resulting in falling glass, which will pose a threat for days to weeks after the storm. Nearly all commercial signage, fences, and canopies will be destroyed. Nearly all trees will be snapped or uprooted and power poles downed. Fallen trees and power poles will isolate residential areas. Power outages will last for weeks to possibly months. Long-term water shortages will increase human suffering. Most of the area will be uninhabitable for weeks or months." From the National Weather Service.

The above photograph is pretty much the reason for this whole post. Courtesy of KeystoneUSA-Zuma/Rex Features.

Too much of a good thing.

Like all living organisms, plants depend on nitrogen as an essential nutrient for growth. In natural ecosystems plants are supplied with nitrogen by microorganisms in the soil that decompose organic matter and break down large, complex organic nitrogen molecules into the smaller, usable forms nitrate and ammonium. Other microbes assist plants with their nitrogen need by fixing atmospheric nitrogen into mineral nitrogen, or by helping plants reach distant soil nitrogen when it is in short supply.

The nitrogen cycle reliably churns along, supporting plant life and all dependent organisms, as long as all of the elements are in place. In agricultural systems, the most important part of the equation is removed when the crops are harvested. Without that plant matter returning to the ground to decompose, soils quickly become nitrogen deficient, and agricultural yield drops. To combat this, farmers must restore the lost nitrogen, and they do so with the addition of nitrogen fertilizers. Unfortunately, fertilizers are often applied in excess as farmers try to maximize yield. Far more nitrogen is added to the system than can be utilized by crops, and the excess finds its way into the atmosphere and bodies of water where it wreaks havoc. A single molecule of nitrous oxide contributes to global climate change with 296 times the global warming potential as a molecule of carbon dioxide. When nitrogen fertilizers reach the water, they promote the growth of algae, leading to massive blooms that choke off marine and aquatic life.

An essay by Allen Good and Perrin Beatty published in this month’s PLoS Biology draws attention to the imbalance of nitrogen fertilizer usage in different regions of the world. For instance, China uses far more nitrogen than is needed for optimal yields, yet their fertilizer use continues to rise. In contrast the countries of sub-Sahara Africa don’t use enough nitrogen and as a result, they have nutrient-poor soils and low yields. When faced with poor water quality due to nitrogen surplus, the European Union established and implemented best nutrient management practices in 1987, resulting in a 56% usage decrease in twenty years.

How was this achieved? Scientists conducted long term studies to determine the optimal amount of nitrogen fertilizer for each crop species in various regions of the world. Ordinarily farmers would apply fertilizers willy nilly with little consideration for the specifics of the plant species, application method, and fertilization rate. The results of these experiments proved that even in well-balanced systems, farmers can reduce the application of nitrogen fertilizer with no loss in yield.

Good and Beatty used this idea and took it a step further by quantifying the potential economic and environmental savings to be gained if fertilizer usage is reduced. First they determined the economic cost associated with the environmental damage of excess fertilizer use. Then they used fertilizer use and price projections to calculate the cost savings if nitrogen use is reduced to match the regional recommendations. All of the countries that were analyzed, which account for 74% of global fertilizer use, required either no change in nitrogen use or a reduction from 5 to 20%. Based on their analysis, Good and Beatty found that directed nutrient management strategies could achieve a total savings of $19.8 billion a year by 2020 and $56 billion a year by 2030. These values are shocking, not only because of the amount of money that is wasted through careless use of fertilizers, but also the magnitude of environmental damage that is incurred year after year. To learn more about the study, and to see Good and Beatty’s recommendations, you can find their essay at PLoS Biology.

Universal flu care.

Designing the annual flu vaccine is not unlike playing the stock market. Each year the World Health Organization (WHO) creates a portfolio of three strains of flu, each representing a different influenza virus. This portfolio is the trivalent inactive vaccine, the official name for your annual flu shot. The strains that are selected are predicted to be the predominant source of flu infection in the upcoming season. Inactive forms of the viruses are combined into one shot, which gives your immune system a preview of what it can expect to fight in the upcoming months. Your body produces antibodies to those strains in advance so that it is ready to attack when flu season begins.

Year after year the scientists at WHO have much success in predicting the most harmful strains of flu; however, their selection process is by no means infallible. While the scientists have plenty of data to draw upon, the decision is, at best, an educated guess. There is no way to know for sure which strains present the greatest risk, and those strains that don’t make it into the vaccine can still infect you and make you sick. Moreover, foresight is greatly limited by the speed with which the viruses evolve. Flu viruses mutate so rapidly that vaccines lose their effectiveness every year. Even after your body builds a supply of antibodies to a particular flu strain, it will be unable to recognize the same strain the following year.

A virus is a very simple entity consisting of a piece of DNA contained within a protein case. Antibodies can only recognize one specific site on the protein case, which they attach to, signaling white blood cells to attack. Usually the antibodies that develop in response to the annual flu vaccine target a highly variable site on the head of the protein case, meaning that a different antibody is needed for each strain of the virus every year. During the 2009 H1N1 pandemic, however, vaccinated patients produced a different kind of antibody. These bound to a region of the protein that is conserved among all Influenza A subtypes, including seasonal flu, avian flu, and swine flu. Additionally, the high degree of conservation among flu viruses suggests that this site on the protein may not mutate from year to year.

Of course the antibody itself cannot be a vaccine, but it will inform the design of a future universal flu vaccine. Now knowing the best region to target, scientists will be able to develop a vaccine that triggers your immune system to produce the antibodies to latch onto the same, conserved site, regardless of the year or strain. Such a vaccine will eliminate the annual guesswork and protect against unexpected strains. You can learn more about this stunning development in immunology as it was published in Science as well as additional reports in Nature News.