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Fish eyes may hold key to blindness cure: study

[email protected] (Agencies)
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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Agencies
June 19,2020

While coughing, fever and difficulty in breathing are common symptoms of COVID-19, a new case study has found that pink eye is also a reason to be tested for the disease.

The study, published in the Canadian Journal of Ophthalmology, determined that conjunctivitis and keratoconjunctivitis can also be primary symptoms of COVID-19.

The researchers noted that in March, a 29-year-old woman arrived at the Royal Alexandra Hospital's Eye Institute of Alberta with a severe case of conjunctivitis and minimal respiratory symptoms.

After the patient had undergone several days of treatment with little improvement -- and after it had been determined that the woman had recently returned home from Asia -- a resident ordered a COVID-19 test.

The test came back positive, according to the researchers.

"What is interesting in this case, and perhaps very different to how it had been recognised at that specific time, was that the main presentation of the illness was not a respiratory symptom. It was the eye," said Carlos Solarte, an assistant professor at the University of Alberta in Canada.

"There was no fever and no cough, so we weren't led to suspect COVID-19 at the beginning. We didn't know it could present primarily with the eye and not with the lungs," Solarte said.

Academic studies at the outset of the pandemic identified conjunctivitis as a secondary symptoms in about 10 to 15 per cent of COVID-19 cases, he said.

Since then, scientists have gained greater knowledge of how the virus can transmit through and affect the body's mucous membrane system, of which the conjunctiva -- the clear, thin membrane that covers the front surface of the eye -- is an extension.

While the finding provides important new health information for the public, it also makes eye exams more complicated for ophthalmologists and staff, the researchers noted.

"The patient in this case eventually recovered well without any issues. But several of the residents and staff who were in close contact with the patient had to be under quarantine," said Solarte.

"Fortunately, none who were involved in her care also tested positive," he said.

Patients coming into an eye clinic with conjunctivitis and keratoconjunctivitis are now treated as potential cases of COVID-19 and extra precautions are taken by staff, according to the researchers.

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Agencies
April 28,2020

As the world grapples with the impact of the novel coronavirus, daily interaction with the outside world --- public and retail spaces, restaurants, educational institutions, and even with each other has been and will continue to be reoriented prioritising personal hygiene and public health.

The sensibilities are building towards and leading to major changes in how the country's food service industry is expected to operate.

Based on a recent consumer survey by restaurant tech platform, Dineout, Indian diners are now ranking safety assurances and premier hygiene as top factors when it comes to choosing a restaurant to dine in.

The survey by Dineout conducted across 20 cities revealed that in a post-COVID-19 era, 81 per cent diners will prefer digital menus at restaurants, while 77 per cent of people will continue to want to dine out.

The survey found that 23 per cent people would prefer continuing with delivery/takeaway and online payment becomes the most preferred option with 60 per cent votes.
 
Diner's response to Contactless Dining:

 

Over 96 per cent demand better waitlist management
 
81 per cent consumers would rather scan a QR on their phone to place an order instead of handling physical menus or tablet-based digital menus.
 
After a dining experience, 60 per cent prefer seamless wallet-based digital payments over cash/cards 85 per cent would choose a digital valet over waiting in possibly contaminated public spaces and 84 per cent would prefer offering digital feedback over physical feedback collection.

 

What do people want to eat?
 
The report also revealed that most of India has been craving Pizza since the lockdown, except in Chennai, Hyderabad and Kolkata where their popular and indigenous Biryani recipes reign supreme. 
 
Which restaurants are diners waiting to go to?
 
77 per cent respondents claimed that they are waiting to dine out with friends and family once the lockdown is lifted.
 
Big Chill, Barbeque Nation and Social emerged as favourites in Delhi, while Mumbaikars picked Global Fusion, Poptates and Asia Kitchen. Bangaloreans miss going to pubs like Toit, Vapour and Barbeque Nation.
 
Aminia, Arsalan and Momo I Am emerge as the top picks in Kolkata.
 
Contrary to popular belief, Delhitties picked vegetarian over non-vegetarian food.
 
Bangaloreans and Lucknowis would rather have their drinks over food.
 
Besides the new parameters for restaurant selection, the factors deciding consumer delight have also seen a major overhaul as hygiene takes precedence. Consumers would prefer that the total number of reservations in a certain period be limited with the option to pre-select the seating, ample amounts of sanitisers at tables along with UV sanitised utensils whenever possible.
 
Hygiene ratings with detailed hygiene information, regular hygiene checks & usage of mask and disposable gloves by waiters are likely to be the new standard, with diners expecting service personnel to sanitise tables & chairs after every use.
 
Dineout recently unveiled the �contactless dining suite' to help restaurants survive and thrive in a post-COVID-19 world. The brand will also provide PPE Safety Kits to Restaurants to help ensure hygiene measures and is facilitating COVID free certification for restaurants through a licensed lab to ensure all microbiological tests are in place before restaurants restart post the lockdown.

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Agencies
August 2,2020

Washington, Aug 2: Children under the age of five have between 10 to 100 times greater levels of genetic material of the coronavirus in their noses compared to older children and adults, a study in JAMA Pediatrics said Thursday.

Its authors wrote this meant that young children might be important drivers of Covid-19 transmission within communities -- a suggestion at odds with the current prevailing narrative.

The paper comes as the administration of US President Donald Trump is pushing hard for schools and daycare to reopen in order to kickstart the economy.

Between March 23 and April 27, researchers carried out nasal swab tests on 145 Chicago patients with mild to moderate illness within one week of symptom onset.

The patients were divided into three groups: 46 children younger than five-years-old, 51 children aged five to 17 years, and 48 adults aged 18 to 65 years.

The team, led by Dr Taylor Heald-Sargent of the Ann & Robert H. Lurie Children's Hospital, observed, "a 10-fold to 100-fold greater amount of SARS-CoV-2 in the upper respiratory tract of young children."

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The authors added that a recent lab study had demonstrated that the more viral genetic material was present, the more infectious virus could be grown.

It has also previously been shown that children with high viral loads of the respiratory syncytial virus (RSV) are more likely to spread the disease.

"Thus, young children can potentially be important drivers of SARS-CoV-2 spread in the general population," the authors wrote.

"Behavioral habits of young children and close quarters in school and daycare settings raise concern for SARS-CoV-2 amplification in this population as public health restrictions are eased," they concluded.

The new findings are at odds with the current view among health authorities that young children -- who, it has been well established, are far less likely to fall seriously ill from the virus -- don't spread it much to others either.

However, there has been fairly little research on the topic so far.

One recent study in South Korea found children aged 10 to 19 transmitted Covid-19 within households as much as adults, but children under nine transmitted the virus at lower rates.

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