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InBrief

best medicine

اندازه فونت:

azadeh arshadi

A shot for all seasons

A better understanding of the immune response to influenza is driving progress towards vaccines that protect against both seasonal and pandemic flu strains.

Flu shots can be hard to sell to the public. Even a run-of-the-mill influenza infection can be debilitating to otherwise

healthy people, and lethal to those who are elderly or frail, so vaccinations are important. The problem is that flu vaccines deliver

inconsistent performance.

“In a good season, we’re up to 60% effectiveness, but in bad, mismatched years it can be as low as 10% or 20%,” says Barney Graham, deputy director of the Vaccine Research Center at the US National Institute of Allergy and Infectious Diseases (NIAID) in Bethesda, Maryland. Current flu vaccines provide protection only against the strains they have been matched to, so a ‘universal’ flu vaccine that provides broader protection against most influenza viruses has been a long-standing dream.

The 2009 swine-flu pandemic, which caught the public-health community off guard and claimed the lives of as many as half-a-million people worldwide, gave the issue new urgency.

“The 2009 pandemic made it obvious and clear that we didn’t have good enough solutions for influenza vaccines,” says Graham.

“We knew the virus, but we weren’t able to make enough vaccine quickly enough.

More-effective manufacturing is one solution but a single inoculation that protects against both seasonal and emerging strains would have much greater impact.

Fortunately, the timing of the pandemic coincided with great progress in the development of technologies for investigating the human response to influenza. “Around 2008 or 2009, people started finding a few broadly neutralizing

antibodies against the influenza virus,”

says Ian Wilson, a structural biologist specializing in vaccine development at Scripps Research Institute in La Jolla, California. “Once people

started looking, many more were discovered.” Now, around 100 years after the ‘Spanish flu’ pandemic of 1918 that killed about 50 million people, multiple universal-vaccine programmes are demonstrating promise in both preclinical and clinical testing. But it remains to be seen whether any will ultimately deliver the broad protection that clinicians seek.

 

 A sticking point for rapid flu tests?

 R apid molecular tests for influenza are as quick as older on-the-spot tests and much more accurate. But that might not be enough to drive widespread adoption.

It begins like many other tests at the doctor’s surgery: a quick swipe inside the nostrilswith what looks like a giant cotton bud,

which is then plunged into medium designed to keep the sample fresh. But it is what happens next that makes the Xpert Xpress molecular influenza test different. A technician places the sample into the machine, which then makes copies of any genetic information it contains. Fluorescence detectors scan for the presence of specific genes. In less than half an hour, the doctor knows with near certainty which influenza virus — if any — is present in the patient’srespiratory tract.

 

The developer of the Xpert Xpress, Cepheid based in Sunnyvale, California, thinks that rapid molecular tests like this will transform flu diagnosis. And other pharmaceutical companies such as Abbott, based in Chicago, Illinois,and Roche of Basel, Switzerland, have created similar diagnostic tools. Since these tests were launched in the United States several years ago, medical providers have raved about their speed and accuracy, which they say makes treatment decisions easy and reduces the burden of disease. But a few problems, including high costs and the risk of sample contamination, make it

hard to predict whether these tests will become the standard diagnostic tool.

 

 INCONSISTENT RESULTS

 

Influenza cuts a seasonal swath of destruction around the world, leading to more than 200,000 hospitalizations and 30,000 deaths each year in the United States alone.

 The virus is highly contagious but treatable, so it is important to identify it as quickly and as accurately as possible. Today, many people who visit a clinic with flu symptoms receive a rapid influenza diagnostic test (RIDT). Unlike molecular tests, such as the Xpert Xpress, RIDTs contain an antibody that sticks to an antigen protein on the flu virus, typically changing colour to show a positive result.

 

The main advantage of RIDTs is their speed — they produce a result in less than 30 minutes.

But they sometimes deliver poor results. “You need a lot of flu to be there, and if there’s not enough, you’ll get a negative result,” says Neil Anderson, who studies infectious diseases at the Washington University School of Medicine in St Louis, Missouri. Children tend to shed a lot of virus particles, he adds, but some adults do not produce enough to give a positive test result even if they have severe symptoms.

 

False-negative results are therefore a big problem. In one clinical study1 involving 600 people, 77% of those with influenza initially received an incorrect negative result from a RIDT. Newer RIDTs have been developed to address such accuracy issues but several researchers say that even these are still not sensitive enough to be reliable. Another type of quick influenza test known as an immunofluorescence assay has similar reliability problems Rapid molecular tests, however, use a different approach. Rather than relying on finding sufficient quantities of antigen, they instead copy long stretches of viral genetic code contained in the sample. Flu viruses have RNA so the tests first immerse the sample in lab-made nucleotides, creating a matching strand of DNA. Multiple rounds of heating and cooling then create many more strands of DNA. This process, called amplification, makes it easy to detect even small quantities of virus. Abbott’s rapid molecular test, called ID Now, amplifies the DNA at a constant temperature.

 

Bad medicine?

 

R ushing drugs to market was supposed to help people in need, but it may be doing more harm than good.

WEEKS before their due date, some women find themselves stunned, peering through glass at their baby,a tiny body covered in sensors and tubes, striving to stay in the world.

Premature birth can be terrifying. Although survival rates for babies born before 37 weeks of pregnancy have steadily improved, they are still significantly worse than those of babies born later, and the likelihood of longer-term health complications is higher.

So any medication that could reduce that risk would be gratefully received – and has been. In 2011, a drug called Makena was approved by the US Food and Drug Administration (FDA) on the basis of a small trial showing that it helped prevent preterm birth. Later, larger studies found that it did not. One hospital even reprted higher rates of gestational diabetes aming women given the drung. Then last month a large trial found that maken was no better than placebo, an FDA committee recommended withdrawing it from the market. The FDA has yet to decide.

It isn’t just Makena. At drug approvals agencies around the world, more and more medications are being rushed to market after limited testing.

 

Making electricity out of dirty gold

 

M ore than 50,000 tons of garbage is produced on daily basis in the country.

According to officials announcement Only 25% of this huge volume of waste is processed! And 75 % of the rest transmitted to one of  the hundreds of waste landfills to be buried or kept in jungles and beaches, because of the lack of waste management in the country. But in the developed countries the garbage is used as a source of energy.

Dr. Hossein Ghanawati, Industrial Microbiologist and Faculty Member of Agricultural Biotechnology Research Institute, interviewed with Daneshmand and described the necessities and difficulties of construction and generating electricity from waste.

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