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.

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News Network
March 5,2020

Bergen, Mar 5: Divorce of parents may impact the academics of children negatively, suggests a new study.

According to the study, parental divorce is associated with a lower grade point average (GPA) among adolescents, with a stronger association seen in teens with more educated mothers.

The study was published in the journal PLOS ONE.

Children and adolescents with divorced or separated parents are known to do less well in school than adolescents with nondivorced parents and to be less well-adjusted, on average, across a spectrum of physical and mental health outcomes.

In the new study, researchers used data from the youth@hordaland study, a population-based survey of adolescents aged 16-19 conducted in the spring of 2012 in Hordaland County, Norway.

19,439 adolescents were invited to participate and 10,257 agreed; of those, 9,166 are included in the current study.

Overall, adolescents with divorced parents had a 0.3 point lower GPA (standard error 0.022, p<0.01) than their peers.

Controlling for parental education reduced the effect by 0.06 points to 0.240 (SE 0.021, p<0.01). This heterogeneity was predominantly driven by maternal education levels, the researchers found.

After controlling for paternal education and income measures, divorce was associated with a 0.120 point decrease in GPA among adolescents whose mothers had a secondary school education level; a 0.175 point decrease when mothers had a Bachelor's level education; and a 0.209 point decrease when mothers had a Master's or PhD level education (all estimates relative to adolescents with a mother who had a basic level of education, such as ISCED 0-2).

Due to the cross-sectional structure of the study, researchers could not investigate specific changes between pre- and post-divorce family life, and future studies are needed to investigate potential mechanisms (such as reduced parental monitoring or school-involvement) which might drive this finding.

Nonetheless, this study provides new evidence that the negative association between divorce and teens' GPA is especially strong in families with more educated mothers.

"Among Norwegian adolescents, parental divorce was hardly associated with GPA among youth whose parents have low educational qualifications. In contrast, among adolescents with educated or highly educated mothers, divorce was significantly associated with lower GPA," said the authors.

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Agencies
June 24,2020

New Delhi, Jun 24: Expanding the testing criterion for coronavirus, the Indian Council of Medical Research has said it should be made widely available to all symptomatic individuals across the country.

"Since test, track and treat' is the only way to prevent spread of infection and save lives, it is imperative that testing should be made widely available to all symptomatic individuals in every part of the country and contact tracing mechanisms for containment of infection are further strengthened," it said in an advisory on 'Newer Additional Strategies for COVID-19 Testing' on Tuesday.

In its revised testing strategy for COVID-19 issued on May 18, the Indian Council of Medical Research (ICMR) had advised testing for all symptomatic Influenza-like illness (ILI) among returnees and migrants within seven days of illness.

All hospitalised patients who develop ILI symptoms, symptomatic individuals living within hotspots or containment zones and healthcare and frontline workers involved in containment and mitigation of coronavirus were also advised testing.

The apex health research body has also advised authorities to enable all government and private hospitals, offices and public sector units to perform antibody-based COVID-19 testing for surveillance to help allay fears and anxiety of healthcare workers and office employees.

The earlier advisories on rapid antibody testing advisories had focused on areas reporting clusters (containment zones), large migration gatherings/evacuees centers and testing of symptomatic ILI individuals at facility level.

Besides, the ICMR on Tuesday also recommended deployment of rapid antigen detection tests for COVID-19 in combination with RT-PCR tests in all containment zones, all central and state government medical colleges and government hospitals, all private hospitals approved by the National Accreditation Board for Hospitals and Healthcare (NABH), all NABL-accredited and ICMR approved private labs, for COVID-19 testing.

All hospitals, laboratories and state governments intending to perform the point-of-care antigen tests need to register with ICMR to obtain the login credentials for data entry.

"ICMR advises all state governments, public and private institutions concerned to take required steps to scale up testing for COVID-19 by deploying combination of various tests as advised," the advisory added.

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Agencies
June 12,2020

Global poverty could rise to over one billion people due to the COVID-19 pandemic and more than half of the 395 million additional extreme poor would be located in South Asia, which would be the hardest-hit region in the world, according to a new report.

Researchers from King's College London and Australian National University published the new paper with the United Nations University World Institute for Development Economics Research (UNU-WIDER) said that poverty is likely to increase dramatically in middle-income developing countries and there could be a significant change in the distribution of global poverty.

The location of global poverty could shift back towards developing countries in South Asia and East Asia, the report said.

The paper, 'Precarity and the Pandemic: COVID-19 and Poverty Incidence, Intensity and Severity in Developing Countries,' finds that extreme poverty could rise to over one billion people globally as a result of the crisis.

The cost of the crisis in lost income could reach USD 500 million per day for the world's poorest people, and the intensity and severity of poverty are likely to be exacerbated dramatically.

The report said that based on the USD 1.90 a day poverty line and a 20 per cent contraction, more than half of the 395 million additional extreme poor would be located in South Asia, which would become the hardest hit region in the world mainly driven by the weight of populous India followed by sub-Saharan Africa which would comprise 30 per cent, or 119 million, of the additional poor.

The report added that as the value of the poverty line increases, a larger share of the additional poor will be concentrated in regions where the corresponding poverty line is more relevant given the average income level.

For instance, the regional distribution of the world's poor changes drastically when looking at the USD 5.50 a day poverty line the median poverty line among upper-middle-income countries.

At this level, almost 41 per cent of the additional half a billion poor under a 20 per cent contraction scenario would live in East Asia and the Pacific, chiefly China; a fourth would still reside in South Asia; and a combined 18 per cent would live in the Middle East and North Africa (MENA) and in Latin America and the Caribbean (LAC), whose individual shares are close to that recorded for sub-Saharan Africa.

India plays a significant role in driving the potential increases in global extreme poverty documented previously, comprising almost half the estimated additional poor regardless of the contraction scenario, the report said.

Nonetheless, there are other populous, low and lower-middle- income countries in South Asia, sub-Saharan Africa, and East Asia and the Pacific accounting for a sizeable share of the estimates: Nigeria, Ethiopia, Bangladesh, and Indonesia come next, in that order, concentrating a total of 18 19 per cent of the new poor, whereas the Democratic Republic of Congo, Tanzania, Pakistan, Kenya, Uganda, and the Philippines could jointly add 11 12 per cent.

Taken together, these figures imply that three quarters of the additional extreme poor globally could be living in just ten populous countries.

The report added that this high concentration of the additional extreme poor is staggering , although not necessarily unexpected given the size of each country's population.

On one hand, data shows that three of these ten countries (Ethiopia, India, and Nigeria) were among the top ten by number of extreme poor people in 1990 and remained within the ranks of that group until 2018.

Despite this crude fact, two of these countries have managed to achieve a sustained reduction in their incidence of poverty since the early 1990s, namely Ethiopia and India, reaching their lowest poverty headcount ratio ever recorded at about 22 and 13 per cent, respectively. Nonetheless, the potential contraction in per capita income/consumption imposed by the pandemic's economic effects could erase some of this progress.

The researchers are now calling for urgent global leadership from the G7, G20, and the multilateral system, and propose a three-point plan to address the impact of the COVID-19 on global poverty quickly.

Professor of International Development at King's College London and a Senior Non-Resident Research Fellow at UNU-WIDER Andy Sumner said the COVID-19 crisis could take extreme poverty back over one billion people because millions of people live just above poverty.

Millions of people live in a precarious position one shock away from poverty. And the current crisis could be that shock that pushes them into poverty.

Professor Kunal Sen, Director of UNU-WIDER said the new estimates about the level of poverty in the world and the cost of the COVID-19 pandemic to the world's poor are sobering.

We cannot stand by and see the hard work and effort of so many be eradicated. We will know what the real impact is in time, but the necessary action to ensure we achieve the Sustainable Development Goals by 2030 needs to be planned now, Sen said.

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