Fish eyes may hold key to blindness cure: study

March 11, 2017

Washington, Mar 11: Scientists, including one of Indian-origin, have identified a chemical signal in the zebrafish brain that helps it regenerate retina, a finding that may help cure blindness in humans.

fisheye

The discovery raises the possibility that human retinas can be induced to regenerate, naturally repairing damage caused by degenerative retinal diseases and injury, including age-related macular degeneration and retinitis pigmentosa, researchers said.

"The prevailing belief has been that the regeneration process in fish retinas is triggered by secreted growth factors, but our results indicate that the neurotransmitter GABA might initiate the process instead," said James Patton, Professor at Vanderbilt University in the US.

"All the regeneration models assume that a retina must be seriously damaged before regeneration takes place, but our studies indicate that GABA can induce this process even in undamaged retinas," said Patton.

It turns out that the structure of the retinas of fish and mammals are basically the same.

Although the retina is very thin - less than 0.5 millimetres thick - it contains three layers of nerve cells: photoreceptors that detect the light, horizontal cells that integrate the signals from the photoreceptors and ganglion cells that receive the visual information and route it to the brain.

In addition, the retina contains a special type of adult stem cell, called Muller glia, that span all three layers and provide mechanical support and electrical insulation. In fish retinas, they also play a key role in regeneration.

When regeneration is triggered, the Muller glia dedifferentiate, begin proliferating, and then differentiate into replacements for the damaged nerve cells. Muller glia are also present in mammalian retinas, but do not regenerate.

Graduate student Mahesh Rao got the idea that GABA - normally a fast-acting neurotransmitter best known for its role of calming nervous activity by inhibiting nerve transmission in the brain - might be the trigger for retinal regeneration.

He was inspired by the results of a study in the mouse hippocampus which found that GABA was controlling stem cell activity.

Working with Patton and assistant professor Dominic Didiano, Rao designed a series of experiments with zebrafish which determined that high concentrations of GABA in the retina keep the Miller glia quiescent and that they begin dedifferentiating and proliferating when GABA concentrations drop.

They tested their hypothesis in two ways: By blinding zebrafish and injecting them with drugs that stimulate GABA production and by injecting normal zebrafish with an enzyme that lowers the GABA levels in their eyes.

Comments

Add new comment

  • Coastaldigest.com reserves the right to delete or block any comments.
  • Coastaldigset.com is not responsible for its readers’ comments.
  • Comments that are abusive, incendiary or irrelevant are strictly prohibited.
  • Please use a genuine email ID and provide your name to avoid reject.
Agencies
February 10,2020

Washington D.C, Feb 10: Children's vulnerability towards depression, anxiety, impulsive behaviour, and poor cognitive performance could be determined by considering the hours of sleep they manage to get.

Sleep states are active processes that support the reorganisation of brain circuitry. This makes sleep especially important for children, whose brains are developing and reorganising rapidly.

In a study by researchers from the University of Warwick -- recently published in the journal Molecular Psychiatry -- cases of 11,000 children aged between 9 and 11 years from the Adolescent Brain Cognitive Development dataset were analyzed to find out the relationship between sleep duration and brain structure.

The study was carried out by researchers Professor Jianfeng Feng, Professor Edmund Rolls, Dr. Wei Cheng and colleagues from the University of Warwick's Department of Computer Science and Fudan University.

Measures of depression, anxiety, impulsive behaviour and poor cognitive performance in the children were associated with shorter sleep duration. Moreover, the depressive problems were associated with short sleep duration one year later.

The reduced brain volume of areas such as orbitofrontal cortex, prefrontal, and temporal cortex, precuneus, and supramarginal gyrus was found to be associated with the shorter sleep duration.

Professor Jianfeng Feng, from the University of Warwick's Department of Computer Science, comments: "The recommended amount of sleep for children 6 to 12 years of age is 9-12 hours. However, sleep disturbances are common among children and adolescents around the world due to the increasing demand on their time from school, increased screen time use, and sports and social activities."

A previous study showed that about 60 per cent of adolescents in the United States receive less than eight hours of sleep on school nights.

Professor Jianfeng Feng further added: "Our findings showed that the total score for behavior problems in children with less than 7 hours sleep was 53 per cent higher on average and the cognitive total score was 7.8 per cent lower on average than for children with 9-11 hours of sleep. It highlights the importance of enough sleep in both cognition and mental health in children."

Professor Edmund Rolls from the University of Warwick's Department of Computer Science also commented: "These are important associations that have been identified between sleep duration in children, brain structure, and cognitive and mental health measures, but further research is needed to discover the underlying reasons for these relationships."

Comments

Add new comment

  • Coastaldigest.com reserves the right to delete or block any comments.
  • Coastaldigset.com is not responsible for its readers’ comments.
  • Comments that are abusive, incendiary or irrelevant are strictly prohibited.
  • Please use a genuine email ID and provide your name to avoid reject.
Agencies
June 4,2020

The World Health Organisation on Wednesday said that anti-malarial drug hydroxychloroquine (HCQ) will return to the solidarity trial for the potential treatment of coronavirus disease.

At a press conference in the WHO headquarters in Geneva, Director General Tedros Adhanom Ghebreyesus said: "On the basis of the available mortality data, the members of the committee recommended that there are no reasons to modify the trial protocol. The Executive Group received this recommendation and endorsed continuation of all arms of the solidarity trial, including hydroxychloroquine."

The world health body had temporarily suspended the usage of HCQ from the solidarity trial for coronavirus treatment on May 25 soon after a study published in one of the most reliable medical journals, which had suggested that the drug could cause more fatalities among COVID-19 patients.

However, the WHO chief said that the decision was taken as a precaution while the safety data was reviewed.

Ghebreyesus also said that the Data Safety and Monitoring Committee will continue to closely monitor the safety of all therapeutics being tested in the solidarity trial.

"So far, more than 3,500 patients have been recruited in 35 countries. WHO is committed to accelerating the development of effective therapeutics, vaccines and diagnostics as part of our commitment to serving the world with science, solutions and solidarity," he said.

Soon after HCQ was suspended from the trial, the Indian government had said that the antimalarial drug has been known for its benefits for a long time and its usage will be continued on the frontline workers, including police and healthcare professionals, as prophylaxis. The government had also said that studies were being conducted and the drug would be included in the clinical trial also for the treatment of coronavirus disease.

US President Donald Trump also had strongly advocated the use of HCQ and called it a "game-changer". He went to the extent of saying that he had taken the medicine.

Launched by WHO and partners, solidarity trial is an international clinical trial to find an effective treatment for COVID-19, including drugs to slow the progression of the disease or improve survival. The trial, which enrols patients from different countries, "will compare four treatment options against standard of care to assess their relative effectiveness against COVID-19", said WHO. 

Comments

Add new comment

  • Coastaldigest.com reserves the right to delete or block any comments.
  • Coastaldigset.com is not responsible for its readers’ comments.
  • Comments that are abusive, incendiary or irrelevant are strictly prohibited.
  • Please use a genuine email ID and provide your name to avoid reject.
Agencies
February 11,2020

Using smartphone for long hours every day may do you more harm than you can probably think of. Researchers have found that spending a lot of time with the device and on social media may lead to mental distress and suicidality among adolescents.

The findings, published in the journal CMAJ (Canadian Medical Association Journal) contains guidance for physicians, parents and teachers on how to help teenagers manage smartphone and social media use for a healthy balance between sleep, academic work, social activity, interpersonal relationships and online activity.

"Physicians, teachers and families need to work together with youth to decrease possible harmful effects of smartphones and social media on their relationships, sense of self, sleep, academic performance, and emotional well-being," said lead author of the study Elia Abi-Jaoude from Toronto Western Hospital in Canada.

This review of evidence, led by the Hospital for Sick Children (SickKids), focuses on smartphone use and does not consider online gaming.

"For adolescents today, who have not known a world without social media, digital interactions are the norm, and the potential benefits of online access to productive mental health information -- including media literacy, creativity, self-expression, sense of belonging and civic engagement -- as well as low barriers to resources such as crisis lines and Internet-based talking therapies cannot be discounted," the authors wrote.

The researchers recommend that doctors should ask teenagers to reduce social media use rather than eradicate it completely and encourage parents to be part of the conversations.

Parents should discuss appropriate smartphone use with teenagers to determine together how to reduce risks and set boundaries.

A recent poll from the US indicates that 54 per cent of teenagers think they spend too much time on their smartphones and about half said they were cutting back on usage.

"Encouragingly, youth are increasingly recognising the negative impact of social media on their lives and starting to take steps to mitigate it," the authors wrote.

Comments

Add new comment

  • Coastaldigest.com reserves the right to delete or block any comments.
  • Coastaldigset.com is not responsible for its readers’ comments.
  • Comments that are abusive, incendiary or irrelevant are strictly prohibited.
  • Please use a genuine email ID and provide your name to avoid reject.