Brain's on-off thirst switch identified

January 27, 2015

Brains on-off

Washington, Jan 27: Scientists have identified neurons that trigger our sense of thirst and those that turn it off.

For years, researchers have suspected that thirst is regulated by neurons in the subfornical organ (SFO), in the hypothalamus. But it has been difficult to pinpoint exactly which neurons are involved.

“When researchers used electrical current to stimulate different parts of the SFO of mice, they got confusing results,” said lead author Yuki Oka, a postdoctoral research scientist in the laboratory of Charles S Zuker, a Howard Hughes Medical Institute Investigator at Columbia University Medical Center (CUMC).

The CUMC team hypothesised that there are at least two types of neurons in the SFO, including ones that drive thirst and others that suppress it.

“Those electrostimulation experiments were probably activating both types of neurons at once, so they were bound to get conflicting results,” said Oka.

To test their hypothesis, Oka and Zuker turned to optogenetics, a more precise technique for controlling brain activity. With optogenetics, researchers can control specific sets of neurons in the brain after inserting light-activated molecules into them.

Shining light onto these molecules turns on the neurons without affecting other types of neurons nearby.

These “mind-control” experiments revealed two types of neurons in the SFO that control thirst: CAMKII neurons, which turn thirst on, and VGAT neurons, which turn it off.

When the researchers turned on CAMK11 neurons, mice immediately began to seek water and to drink intensively.

This behaviour was as strong in well-hydrated mice as in dehydrated ones. Once the neurons were shut off – by turning off the light – the mice immediately stopped drinking.

The researchers also found that light-stimulation of the CAMKII neurons did not induce feeding behaviour. In addition, light-induced thirst was specific for water and did not increase the animals’ consumption of other fluids, including glycerol and honey.

Similar experiments with VGAT neurons showed that these neurons act to turn off thirst. When the researchers turned on these neurons with light, dehydrated mice immediately stopped drinking, even if they were drinking water.

“Together, these findings show that the SFO is a dedicated brain system for thirst,” said Oka.

“The SFO is one of few neurological structures that is not blocked by the blood-brain barrier – it’s completely exposed to the general circulation,” said Oka.

“This raises the possibility that it may be possible to develop drugs for conditions related to thirst,” Oka added.

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Agencies
May 2,2020

Clinician-scientists have found that Irish patients admitted to hospital with severe coronavirus (COVID-19) infection are experiencing abnormal blood clotting that contributes to death in some patients.

The research team from the Royal College of Surgeons in Ireland found that abnormal blood clotting occurs in Irish patients with severe COVID-19 infection, causing micro-clots within the lungs.

According to the study, they also found that Irish patients with higher levels of blood clotting activity had a significantly worse prognosis and were more likely to require ICU admission.

"Our novel findings demonstrate that COVID-19 is associated with a unique type of blood clotting disorder that is primarily focussed within the lungs and which undoubtedly contributes to the high levels of mortality being seen in patients with COVID-19," said Professor James O'Donnell from St James's Hospital in Ireland.

In addition to pneumonia affecting the small air sacs within the lungs, the research team has also hundreds of small blood clots throughout the lungs.

This scenario is not seen with other types of lung infection and explains why blood oxygen levels fall dramatically in severe COVID-19 infection, the study, published in the British Journal of Haematology said.

"Understanding how these micro-clots are being formed within the lung is critical so that we can develop more effective treatments for our patients, particularly those in high-risk groups," O'Donnell said.

"Further studies will be required to investigate whether different blood-thinning treatments may have a role in selected high-risk patients in order to reduce the risk of clot formation," Professor O'Donnell added.

According to the study, emerging evidence also shows that the abnormal blood-clotting problem in COVID-19 results in a significantly increased risk of heart attacks and strokes.

As of Friday morning, the cases increased to 20,612 cases in Ireland, with 1,232 deaths so far, according to the Johns Hopkins University.

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Agencies
February 24,2020

Singapore, Feb 24: Last week Singapore's Ministry of Trade and Industry revised their 2020 GDP growth projections downwards to -0.5 to 1.5 per cent, confirming fears of economic fallout from the coronavirus COVID-19. Just three days earlier, while visiting Changi Airport, the Prime Minister told the media that the country is bracing for a significant hit on the economy and the possibility of a recession.

In the budget announcement on February 18, various measures to help affected companies were announced.

This included a jobs support scheme to help companies retain workers that will see the government offset 8 per cent of wages up to SGD3,600(USD2,600) per worker, per month, for a three-month period. Companies will also get a 25 per cent rebate on their taxes for the year capped at SGD15,000 (USD10,800) per company.

There will be additional support for sectors directly affected by the virus outbreak such as tourism, aviation and retail. Qualifying companies will be given property tax rebates and can apply for temporary bridging loans to ease cash flow. Rebates will be offered on aircraft landing and parking charges as well as rental rebates for shops and cargo agents at Changi Airport.

Overall, the economic package will cost Singapore some USD 4.6 billion, well in excess of the USD 500 million some analysts had predicted. The resulting spending plan including the virus economic package will see a budget deficit of SGD 10.9 billion or 2.1 per cent of GDP, the highest since the Asian financial crisis of 1997.

It is hoped that with financial support, companies in Singapore will not only be able to ride through the current rough patch but be able to position themselves better to take off once the economic crisis brought upon by the contagion is over.

Which then are the Singapore companies that can potentially ride out the current storm and emerge stronger?

Aviation and hospitality firms are among those most impacted by the virus outbreak and Singapore Airlines (SIA) comes to mind. SIA is a well-run company but has seen its share price fall about 5.2 percent since the beginning of the year. In the short term, revenue and profits will no doubt be affected but it will recover in the long run.

Hospitality sector companies like Ascott Residence whose main sponsor is Capitaland, Southeast Asia's largest landlord, and CDL Hospitality, have seen 1.5 and 5.5 percent (respectively) shaved off their share prices since the start of the year.

In reporting financial results for the quarter which ended in December on February 14, Alibaba CEO Daniel Zhang said that due to the virus, they are seeing large changes in buying patterns. With widespread home confinement, there is a growing demand for delivery services including online food and grocery delivery, as well as office apps and streaming entertainment.

Similarly, in Singapore, with more people staying and working from home, the three main food delivery services, Grab Food, Foodpanda and Deliveroo, are doing roaring business. All three are privately held.

In late January, as the scale of the outbreak became more apparent, investors began pouring money into health-product firms in Asia that they think will benefit from the virus outbreak.

Bloomberg reported that when Chinese pharmaceutical companies like Da An Gene Co, Xilong Scientific and Shanghai Kehua Bio-Engineering said they have developed kits for detecting the virus, their stocks soared to hit the 10 per cent daily limit. Firms manufacturing protection gear and air-cleaning equipment climbed more than 10 per cent in Japan, while Malaysian rubber gloves producers climbed at least 5 per cent.

Naturally, many would view that pharmaceutical companies that have the technology and expertise to develop drugs to treat patients with the virus or are able to develop a vaccine, would stand to benefit from the coronavirus outbreak.

Firms like and Johnson & Johnson, Pfizer, MSD, GlaxoSmithKline (GSK) and Sanofi are the pharmaceutical behemoths that dominate the global vaccine market.

However, industry experts speaking to the BBC warned that a pot of gold is not necessarily waiting for any company that successfully develops a vaccine. Although the global vaccine market is expected to grow to USD60 billion this year, it is costly and time-consuming to develop and pass it through for use by the general public.

It is also unclear if Indian pharmaceutical firms will be able to benefit from the demand for medicines that can treat or prevent the virus.

India is the world's largest manufacturer of generic drugs and it supplies 20 percent of the world's drugs by volume. However, it sources 70 percent of its raw material from China. If supplies are disrupted beyond a month to a month and a half, they may see a slow-down in production. According to a CNN report, the companies that are most impacted by material shortages are GSK India, Pfizer (PFE) and Cipla. Other companies like Aurobindo Pharma, Cadila Healthcare and Sun Pharma are said to be carefully monitoring the situation.

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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."

15 countries with the highest number of cases, deaths due to the Covid-19 pandemic

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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