A gene variant (变体) that causes the “alcohol flush (脸红)” reaction increases the risk of heart disease by causing inflammation of blood vessels (脉管), especially in drinkers. Around 8 percent of the world’s populations has a gene variant called ALDH2*2 that impairs the body’s ability to break down alcohol and causes unpleasant symptoms such as flushing soon after people drink. Now, researchers have shown why this change also raises the risk of heart disease.

“We are trying to understand why ALDH2*2 is associated with a higher risk of coronary arte (冠状动脉) disease at a cellular (细胞的) level,” says Hongchao Guo at Stanford University in California.

The ALDH2*2 gene encodes one version of the enzyme (酵素) alcohol dehydrogenase (脱氢酶), which breaks down the toxic acetaldehydes (乙醛) produced when alcohol is metabolized (代谢), and also mops up other harmful substances known as free radicals.

The gene variant also impairs the growth of new blood vessels. “That means that when there is a heart attack, when there is a need of blood vessel growth, carriers have less ability to generate new blood vessels,” says Guo.

The team found that an existing diabetes (糖尿病) drug called empagliflozin may reduce these harmful effects in people with ALDH2*2 who drink a lot of alcohol. But for Wu, the take-home message is clear. “If you’re missing this enzyme, try not to drink,” he says. “If you drink consistently, you are at much higher risk of heart disease, hypertension, diabetes and cancer.”

Given its many negative consequences, there has been debate about why this change spread and became common, today being found in more than a third of people of cast Asian origin.

“My only explanation is that if you are missing this enzyme, you tend to drink less and there’s therefore less chance of you becoming alcoholic,” says Wu.

The unique ocean animals were discovered by a team of scientists led by Dr. Christine Dudgeon from Australia’s University of Queensland during a 12 year global conservation study.

The newly-found sharks have evolved (进化) to survive in low oxygen environments, enabling them to hunt during low tides. The researchers believe their ability to use their fins (鳍) to walk affords the sharks a remarkable edge over the smaller animals they try to hunt. “While they are super hunters in their shallow habitat, the tiny sharks present no threat to people,” says Dudgeon. “At less than a meter long on average, they’re incredibly cute little animals that do not look like sharks at all,” she adds.

A DNA analysis of skin samples from the live fish suggests that walking sharks broke away from their original population and became a distinct species about nine million years ago. Though that may appear to be a long time ago, it is relatively recent given that sharks have been around for more than 400 million years. In fact, Dudgeon and her team believe walking sharks are the youngest kind of sharks on Earth!

The researchers say that the sharks’ small numbers and small habitat make them extremely vulnerable (易受伤害) to natural disasters and overfishing. They are currently on the Nature Red List, which lists species at risk. Dudgeon and her team believe sensible conservation management plans are urgently needed to protect the walking sharks and other endangered animals from further threats.

An infectious disease is a disease that is caused by the invasion of a host by pathogens（病原体）whose activities harm the host’s tissues and can be spread to other individuals.

Microorganisms（微生物）capable of causing disease are called pathogens. A true pathogen is an infectious agent that causes disease in any possible host. The terms “infection” and “disease” are quite different. In order to cause disease, pathogens must be able to enter the host body, stick to specific host cells, invade and multiply and do damage to host tissues.

Pathogens may be spread through either direct or indirect contact. Direct contact occurs when an individual is infected by contact with the infection source. It also includes taking in the infectious droplets released by sneezing or coughing. Indirect contact occurs when a pathogen can survive the environment outside its host for a long period of time. So lifeless objects that are polluted by direct contact with the infection source may be the indirect contact for easily infected group.

Public health measures typically involve killing the pathogen from its source or from its route of spread. Those measures include ensuring a safe water supply, effectively treating waste water, and initiating animal control and vaccination（疫苗）programs, etc. Personally, the first line of defense is to keep pathogen at bay by following good personal hygiene（卫生）habits. Prevent infection before it begins and avoid spreading it to others with some easy measures, such as washing hands, getting vaccinated and so on.

Man never stops fighting against all kinds of infectious diseases. But in the past two decades at least a dozen “new” disease have been identified, and traditional diseases that appeared to be “on their way out” are re-emerging. Globally, infectious diseases remain the leading cause of death. Clearly, the ballet has not been won. Nevertheless, it is increasingly difficult for most of us to deny the claims of science. We are continually presented with great amounts of relevant scientific and medical knowledge, which encourages us to take more responsibility for our own health.