The Update is a monthly digest of all that is interesting, exciting and new in the world of medicine and medical science, presented in a curated and convenient package.
1.Measles Wipes Out Immune System's Memory, Study Finds
Measles affects more than 7 million people a year and causes more than 100,000 deaths. Photograph: Cynthia Goldsmith/Centers for Disease Control/PA
Measles causes long-term damage to the immune system, leaving children who have had it vulnerable to other infections long after the initial illness has passed, research has revealed.
Two studies (1)(2) of unvaccinated children in an Orthodox Protestant community in the Netherlands found that measles wipes out the immune system’s memory of previous illnesses, returning it to a more baby-like state, and also leaves the body less equipped to fight off new infections.
Measles eliminated between 11% and 73% of children’s protective antibodies, the research found.
Globally, measles affects more than 7 million people each year and causes more than 100,000 deaths. Reduced vaccination rates have led to a nearly 300% increase in measles infections since 2018.
Previously, scientists had inferred a longer-term impact on the immune system because deaths from other infections were seen to go up after a measles outbreak, and because the virus directly attacks the immune system. The latest work for the first time uncovers the extent of the damage.
2.New Gene-Editing Tool Could Fix Genetic Defects—with Fewer Unwanted Effects
The gene-editing method CRISPR has transformed biology, but remains difficult to implement in practice due in part to the fact that it causes double-stranded breaks which can cause unintended effects.
Making such double-stranded breaks in DNA can result in unwanted genetic material being inserted or deleted, which can have consequences including activating genes that cause cancer.
In 2016 a team of Harvard University and MIT researchers developed another method, called base editing, which allows scientists to make precise edits to single DNA letters without relying on double-stranded breaks.
This technique, however, can only be used to fix four out of the 12 types of “point” genetic mutations, which include insertions, deletions and combinations of the two.
Now the team developed a new gene-editing tool that avoids these double-stranded breaks and can correct all 12 types of point mutations.
The researchers used their new technique, dubbed “prime editing,” in lab-grown human cells to correct the genetic defects that cause sickle cell disease and Tay-Sachs disease, they report in a study published Monday in Nature.
They say their method is more efficient than traditional CRISPR (except for in certain cell types) and has fewer off-target effects.
In principle, it could correct about 89 percent of known human genetic defects that cause diseases, although it is still a very new technique and requires much more study before it can be used to treat humans.
3.FDA Recalls Ranitidine Over Potential Cancer Causing Contaminant
There has been a global recall of products, including a suspension on the distribution of Zantac, produced by Swiss drug manufacturer Novartis. Drew Angerer / Getty Images
Ranitidine, generically known as Zantac, belongs to a class of drugs known as Histamine-2 blockers commonly used to treat and relieve heartburn.
In September 2019, the FDA announced that preliminary tests found low levels of N-nitrosodimethylamine (NDMA), an impurity that is considered a possible carcinogen, especially upon exposure to high doses over a long period of time.
The FDA ― which noted that NDMA can be found in “water and foods, including meats, dairy products and vegetables” ― said that “although NDMA may cause harm in large amounts, the levels in ranitidine from preliminary tests barely exceed amounts you might expect to find in common foods.”
Since then, the agency has stated in October 2019 that instead of just a little NDMA with a very low risk, new “early, limited testing” has found unacceptable levels of NDMA in ranitidine samples.
The FDA has said it is working with international regulators and with the industry to determine the source of the impurity, and since then, major distributors of the drug such as Novartis/Sandoz and Apotex have recalled products. Ranitidine distributed by other companies still remains on store shelves.
In the United Arab Emirates, The Ministry of Health and Prevention (MoHAP) has issued a circular to all health facilities and practitioners, informing them about the precautionary suspension of the registration, importation and distribution of all medicines containing ranitidine, while asking patients to continue with their current medication until replacement is found.
The ministry said it will not permanently withdraw affected medicines until the acceptable ratio of NDMA, is established by the international health authorities.
The testing of NMDA levels in ranitidine was initiated after reports in July 2018 stated that Valsartan, a common drug used to treat high blood pressure, was also tainted with NMDA.