Category: Lab Tests and Imaging

Categories : COVID Lab Tests and ImagingTags :

COVID Variants May Increase False Negative Results, FDA Warns

On By ModernMedia

The UK variant of the SARS-CoV-2 virus, known as B.1.1.7 could affect the accuracy of certain molecular COVID tests, causing increased false negative results, the US Food and Drug Administration (FDA) has warned.

A false negative from the UK variant could happen if the variant’s mutation happened to be in a part of the virus’ genome that was assessed by that test. However, genetic tests that target multiple parts of the virus genome are less likely to be affected by the new variants, the FDA advises.

Although the possibility of false negative results are to be expected from almost all tests, the effect of the COVID variants could impact the ability to properly monitor the disease, as well as complicating diagnosis.  

The FDA issued an alert on Friday, saying that they monitor tests which have received an Emergency Use Authorisation (EUA). They highlight three tests as being affected, with potentially less sensitivity to the mutations:

  • Accula SARS-Cov-2 Test, from Mesa Biotech
  • TaqPath COVID-19 Combo Kit, from Thermo Fisher Scientific)
  • Linea COVID-19 Assay Kit, from Applied DNA Sciences

However, the warning for Accula test was a result of “an abundance of caution”, and the latter two assess multiple genetic targets, so they are not likely to be impacted. The FDA issued recommendations for the users of these devices.The FDA’s warning was prompted by computer simulations showing reduced efficacy in certain tests for the virus variant.

In their press release, the FDA did not specifically mention whether any tests may be affected by mutations in the South African virus variant.

Source: MedPage Today

Categories : Cancer Lab Tests and ImagingTags :

New Multi-cancer Blood Test Offered by NHS

On By ModernMedia

A new blood test developed by the California-based Grail company tests for DNA methylation, and is supposedly able to screen for over 50 cancer types this way.

The NHS is to offer the test to 165 000 people from the middle of next year, with 140 000 screened through their medical records and the remaining 25 000 through referrals from suspected symptoms. It is hoped that widespread screening and early detection will drastically improve cancer survival rates, consequently easing pressure on healthcare services.

Lawrence Young, a professor of molecular oncology, at Warwick University, said the Galleri test was one of several novel blood tests being developed to spot cancer early on. “A publication from the Circulating Cell-free Genome Atlas consortium examining the Galleri test in 6 689 participants has generated very encouraging results in more than 50 different cancers at different stages of development.”

However, there was disagreement from some cancer experts regarding Galleri’s  potential effectiveness. Paul Pharoah, a professor of cancer epidemiology, at Cambridge University, said that it was premature for the NHS to embrace an unproven test. He said, “The Galleri blood test is a test that might be able to detect cancer in the blood in individuals with early cancer, though the evidence that it does this effectively is weak,” Pharoah said. According to him, only a single published paper on the tests was available, wherein they detected a mere 25% of early-stage cancers and under half of late-stage cases.

Source: The Guardian

Categories : Lab Tests and ImagingTags :

New Minimally Invasive Way to Sample Interstitial Fluid

On By ModernMedia

A new method to extract dermal interstitial fluid (ISF) for analysis has been reported. ISF contains a large number of biomarkers which can be used for diagnosis.

The minimally invasive process uses an array of almost invisibly small needles, approximately one quarter of a millimetre long. These were pressed to the skin and suction applied. Care needed to be taken so that the needles did not poke into microcapillaries in the skin and thus contaminate the sample with blood. 

Blood is often used for testing, comprising some 6% of the human body’s fluids, but some 10 000 compounds are found in ISF and 12% of the chemicals are not found in the blood. With the technique, the researchers were also able to measure the effects of glucose and caffeine, which are dynamically active. Traditional methods used to extract are quite invasive; using a needle to withdraw ISF from a vacuum-induced blister, or surgically inserting tubes underneath the skin.

Although the procedure is still time consuming, taking some 20 minutes per patient, it compares to the ~40 minutes required to form a vacuum blister in some ISF sampling protocols. The small needle injuries healed within a day, and there was minimal irritation.

This form of testing could have many applications, such as skin toxicological studies and monitoring glucose levels.

The journal article has been published in Science Translational Medicine.

Source: News-Medical.Net

Categories : Lab Tests and ImagingTags :

Simple New Method to Improve Time Release of Drugs

On By ModernMedia

Researchers have developed a new method to measure the release of drugs over time, using a simple method.

OxyContin, containing the opiate oxycodone, was intended to offer 12-hour pain relief. Instead, in some patients it dissolved much more quickly, causing them to take it more frequently and ultimately become addicted. But assessing how a drug dissolves in the body is surprisingly tricky. Drug dissolution has to be measured under laboratory conditions that come as close as possible to mimicking what happens in the body.

Corresponding author William Grover, associate professor of bioengineering at the Marlan and Rosemary Bourns College of Engineering explains: “We directly measured dissolution profiles of single drug granules, which are the little spheres you see when you open up a capsule. We accomplished this using a vibrating tube sensor, which is just a piece of glass tubing bent in the shape of a tuning fork.”

Many factors influence the way a drug is dissolved in the body, such as the chemical composition and pH of the fluid, the patient’s sex and their metabolism. Meals taken also have a strong impact: taking a fatty meal increases the amount of oxycodone released from OxyContin by 25%.

Pharmaceutical companies simulate these conditions in test vessels to build a profile of how the drug works over time, but this has its drawbacks. The position of tablets in the vessels can affect dissolution rates; equipment can become clogged; the process is very time-consuming and they only provide brief snapshots over time.

The new approach takes a radically different approach, measuring the mass of a drug granule as it dissolves. This is accomplished by changes in the resonant frequency, which can be measured over time instead of being sampled.

Using the technique on three proton-pump inhibitors, the researchers found considerable variations between name-brand and generic formulations of the drugs, affecting the rate at which the drugs are absorbed by patients.

“Our technique is much cheaper and easier to perform than conventional methods, and that enables pharmaceutical companies to do more tests in a wider variety of conditions,” said Grover. “We can also easily see differences in dissolution between individual particles in a drug. That should help pharmaceutical companies improve and monitor the consistency of their manufacturing processes.”

Source: Medical Xpress