Rapid Zika Test Is Introduced by Researchers

A paper-based rapid test for the Zika virus was introduced on Friday by a consortium of research groups.
The core of the test kit is a piece of paper covered with yellow dots that turn purple in the presence of Zika virus RNA. Although the test is relatively fast and simple, it requires preliminary heating to amplify a sample’s RNA, which can be done in most laboratories.
The test, which gives results in two to three hours, “is much faster and cheaper than the P.C.R. tests used now,” said James J. Collins, a bioengineer at the Massachusetts Institute of Technology who is one of the test designers.
It should cost less than $1 per test, said Keith Pardee, a University of Toronto biochemist and another test designer.
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Dr. Collins took a cell’s normal reproductive “machinery” — including proteins, nucleic acids and ribosomes — and freeze-dried it on paper. Thework was described in the journal Cell.
The color change can be read by the eye or by an extra-sensitive scanner that may eventually be able to measure viral loads in the blood sample.
The test has worked on Zika-infected monkey blood, which was used because human samples were hard to obtain in time. Now, Dr. Collins said, “we’re talking with groups in Colombia and Brazil about testing it in the field.”
The collaboration also included scientists from Harvard’s Wyss Institute, the Broad Institute, Cornell, Arizona State and Boston University.

Ask Well: Taking a Daily Aspirin

Adults ages 50 to 69 who are at high risk for heart attack or stroke should take a daily low-dose aspirin to prevent both heart attacks and strokes as well colorectal cancer. That’s the latest advice from the United States Preventive Services Task Force, an influential expert panel that published a final recommendation last month in Annals of Internal Medicine.

It was the first time a major medical organization took this “new approach” of endorsing the broad use of aspirin to prevent cancer, “which makes a great deal of sense,” said Eric Jacobs, a researcher at the American Cancer Society. The recommended dose is a low-dose or “baby” aspirin, typically sold in doses of 81 milligrams.

Low-dose aspirin has long been recommended for some people who have had a heart attack or some forms of stroke, and for certain people at high risk for heart disease. Several of the factors that put one at risk for heart disease — such as obesity and being physically inactive — also play a role in colon cancer.

Some experts think aspirin is too risky for people who have never suffered a heart attack, since aspirin increases the risks of potentially dangerous internal bleeding.

But the task force’s review of the evidence concluded that people in their 50s and 60s who have at least a 10 percent chance of having a heart attack or stroke over the next 10 years could benefit from a daily low-dose aspirin. Those in their 60s are at greater risk for bleeds, which increase with age, so doctors should weigh risks and benefits in individual patients. There is no recommendation for aspirin use for people under 50 or for those 70 and older.

If you’ve ever had a gastrointestinal bleed or ulcer, you probably should not take aspirin. Blood thinners, nonsteroidal anti-inflammatory drugs, omega-3 supplements and uncontrolled high blood pressure also increase your risk of bleeding, and the risk of a bleed is higher for men than for women. Daily aspirin therapy should continue for at least 10 years.

Aspirin may also lower the risk of other types of cancer, including esophageal and stomach cancers, as well as cancers of the breast, prostate and lung, though the level of evidence for these “is too weak to draw strong conclusions” Dr. Jacobs said.

To Keep Obesity at Bay, Exercise May Trump Diet

Young rats prone to obesity are much less likely to fulfill that unhappy destiny if they run during adolescence than if they do not, according to a provocative new animal study of exercise and weight. They also were metabolically healthier, and had different gut microbes, than rats that keep the weight off by cutting back on food, the study found. The experiment was done in rodents, not people, but it does raise interesting questions about just what role exercise may play in keeping obesity at bay.

For some time, many scientists, dieting gurus and I have been pointing out that exercise by itself tends to be ineffective for weight loss. Study after study has found that if overweight people start working out but do not also reduce their caloric intake, they shed little if any poundage and may gain weight.

The problem, most scientists agree, is that exercise increases appetite, especially in people who are overweight, and also can cause compensatory inactivity, meaning that people move less over all on days when they exercise. Consequently, they wind up burning fewer daily calories, while also eating more. You do the math.

But those discouraging studies involved weight loss. There has been much less examination of whether exercise might help to prevent weight gain in the first place and, if it does, how it compares to calorie restriction for that purpose.

So for the new study, which was published last week in Medicine & Science in Sports & Exercise, researchers at the University of Missouri in Columbia and other schools first gathered rats from a strain that has an inborn tendency to become obese, starting in adolescence. (Adolescence is also when many young people begin to add weight.)

These rats were young enough, though, that they were not yet overweight.

After weighing them, the researchers divided the animals into three groups.

One group was allowed to eat as much kibble as they wished and to remain sedentary in their cages. These were the controls.

Another group, the exercise group, also was able to eat at will, but these animals were provided with running wheels in their cages. Rats like to run, and the animals willingly hopped on the wheels, exercising every day.

The final group, the dieting group, was put on a calorie-restricted meal plan. Their daily kibble helpings were about 20 percent smaller than the amount that the runners ate, a portion size designed to keep them at about the same weight as the runners, so that extreme differences in body size would not affect the final results.

After 11 weeks, all of the animals were moved to specialized cages that could measure their metabolisms and how much they moved around. They then returned to their assigned cages for several more weeks, by which time they were effectively middle-aged.

At that point, the control animals were obese, their physiques larded with fat.

The runners and the lower-calorie groups, however, although they also had gained ounces, had put on far less weight than the controls. None were obese.

Both exercise and portion control, in other words, had effectively protected the animals against their fated fatness.

But beneath the skin, the runners and the dieters looked very unalike. By almost all measures, the runners were metabolically healthier, with better insulin sensitivity and lower levels of bad cholesterol than the dieters. They also burned more fat each day for fuel, according to their metabolic readings, and had more cellular markers related to metabolic activity within their brown fat than the dieting group. Brown fat, unlike the white variety, can be quite metabolically active, helping the body to burn additional calories.

Interestingly, the runners also had developed different gut microbes than the dieters, even though they ate the same food. The runners had greater percentages of some bacteria and smaller populations of others than the dieters or the control group; these particular proportions of gut bugs have been associated in a few previous studies with long-term leanness in both animals and people.

Perhaps most striking, “the runners showed no signs of compensatory eating or compensatory inactivity,” said Victoria Vieira-Potter, an assistant professor of nutrition and exercise physiology at the University of Missouri who oversaw the study. They didn’t scarf down more food than the control group, despite running several miles every day and, according to the specialized cages, actually moved around more when not exercising than either of the other groups of rats.

In essence, the runners, while weighing the same as the dieters at the end of the study, seemed better set up to avoid weight gain in the future.

Of course, these were rats, which do not share our human biology or our tangled psychological relationships with food and body fat.

This study also involved young, normal-weight rodents and cannot tell us whether exercise or dieting alone or in combination would aid or hinder weight loss in people (or animals) who already are overweight, Dr. Vieira-Potter said. Metabolisms change once a body contains large amounts of fat, and it becomes increasingly difficult to permanently drop those extra pounds.

So better to avoid weight gain in the first place, if possible. And in that context, she said, “restricting calories can be effective,” but exercise is likely to be more potent in the long term and, of course, as common sense would tell us, doing both—watching what you eat and exercising—is best of all.