A single mutation in Zika virus results in microcephaly, says research
According to a research published on Thursday, Oct. 28 in the journal Science by the American Association for the Advancement of Science, a genetic mutation, probably occurring in 2013, gave the Zika virus the ability to cause severe fetal microcephaly. The findings clarify how the virus evolved from a relatively harmless disease to a pathogen of global concern.
The Zika virus first appeared in 1947 when it was found in monkeys from the Zika Forest in Uganda. However, it was only in 1954 that the first cases in humans were reported in Nigeria. Brazil has notified the first cases of Zika virus in 2015, in Rio Grande do Norte and Bahia.
Since 2016, the Zika virus epidemics on the American continent have been declared a public health emergency by the World Health Organization ), and scientists were unable to determine how the virus, which caused mild infections, triggered serious neurological syndromes.
For study analysis, researcher Ling Yuan and his team at the Beijing Academy of Sciences compared virus strains of Zika present in the South American epidemics in 2015 and 2016 and the ancestor strains of the virus circulating in Cambodia in 2010. They detected a critical mutation that conferred on it the ability to cause microcephaly due to fetal infection in mice. The mutation in the gene was called "S139N", the number refers to the position (139) of a structural protein of the virus, called PrM. The transformation occurred by replacing the serine amino acid present in the genetic code of the virus with the amino acid arginine at a specific point on the prM structural protein on the outer membrane of the virus. In cell culture tests, scientists that this mutation made the virus more lethal to the precursor cells of human neurons in culture compared to the ancestral form. As the Zika virus accumulated numerous changes in its genome between 2010 and 2016, the scientists decided to construct and test seven different mutant viruses. Of all the variants, the one that had the S139N mutation caused a considerably more severe microcephaly and increased the lethality for the embryos of rats.
According to the results, the S139N mutation probably arose around 2013, coinciding with that of the first reports of cases of microcephaly and Guillain-Barré syndrome linked to Zika infection.
Low-energy diet may improve sleep disorders
A total of 63 men - aged 30 to 65 years - who suffered from moderate to severe obstructive sleep apnea were analyzed. Participants had a body mass index between 30 and 40. Among these patients, 58 completed a low-energy diet for nine weeks and then started a weight maintenance program with nutrition and exercise counseling during one year.
Stress can disrupt the treatment of infertility
Although many fertility clinics already adopt stress management programs - yoga, cognitive therapy and biofeedback - the role of stress in infertility continues to be a topic for debate. Some experts in the field believe that infertility undoubtedly causes stress, but stress does not cause infertility.