High fat diet may cause changes in the brain: study

October 24, 2016

Washington, Oct 24: In a recent study, scientists have discovered a new mechanism that regulates obesity. The study shows that this new mechanism can potentially be targeted to treat obesity.

highfatSenior author of the study Makoto Fukuda said, "It's well known that the brain is involved in the development of obesity, but how a high-fat diet changes the brain so it triggers the accumulation of body fat is still unclear."

The team studied the mouse Rap1 gene, which is expressed in a variety of tissues, including the brain where it is involved in functions such as memory and learning. Little was known, however, of the role brain Rap1 plays in energy balance.

To explore the role Rap1 plays in a mouse model, the scientists selectively deleted the Rap1 gene in a group of neurons in the hypothalamus, a region of the brain that is involved in regulating whole-body metabolism.

The scientists had two groups of mice. In one group, the mice were genetically engineered to lack the Rap1 gene, while the control group had a functional Rap 1 gene. Then, the scientists fed the mice in both groups a high-fat diet in which 60 percent of the calories came from fat.

As expected, the control mice with a working Rap1 gene gained weight, but, in comparison, the mice that lacked Rap 1 had markedly reduced body weight and less body fat. Interestingly, when both groups of mice were fed a normal diet, both showed similar weights and body fat.

The scientists then looked closer at why the mice lacking the Rap1 gene had not gained weight despite eating a high-fat diet.

"We observed that the mice lacking Rap1 were not more physically active. However, they ate less and burned more body fat than mice with Rap1," said Fukuda.

Adding, "These observations were associated with the hypothalamus producing more of a hormone that reduces appetite, called POMC, and less of hormones that stimulate appetite, called NPY and AgRP." These mice also had lower levels of blood glucose and insulin than controls.

The scientists also were interested in studying whether leptin changed in mice lacking Rap1.

Leptin, the 'satiety hormone' produced by fatty tissue, helps regulate body weight by inhibiting appetite. Obese people, however, do not respond to leptin's signals of satiety, and the blood levels of leptin are higher than those in non-obese people. Leptin resistance is a hallmark of human obesity.

Mice that lacked Rap1 and ate a high-fat diet, on the other hand, did not develop leptin resistance; they were able to respond to leptin and this was reflected in the hormone's lower blood levels.

The team also tested the effect of inhibiting Rap1 with drugs instead of deleting the gene on mice on a high-fat diet. The scientists inhibited RAP1 action with inhibitor ESI-05.

"When we administered ESI-05 to obese mice, we restored their sensitivity to leptin to a level similar to that in mice eating a normal diet. The mice ate less and lost weight," he said.

The scientists have shown a new mechanism by which the brain can affect the development of obesity triggered by consuming a high-fat diet.

Consuming a high-fat diet results in changes in the brain that increase Rap1 activity, which in turn leads to a decreased sensitivity to leptin, and this sets the body on a path to obesity.

"This new mechanism involving Rap1 in the brain may represent a potential therapeutic target for treating human obesity in the future," said Fukuda.

The study appeared in Cell Reports today.

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Agencies
July 7,2020

The World Health Organization (WHO) is reviewing a report that suggested its advice on the novel coronavirus needs updating after some scientists told the New York Times there was evidence the virus could be spread by tiny particles in the air.

The WHO says the Covid-19 disease spreads primarily through small droplets, which are expelled from the nose and mouth when an infected person breaths them out in coughs, sneezes, speech or laughter and quickly sink to the ground.

In an open letter to the Geneva-based agency, 239 scientists in 32 countries outlined the evidence they say shows that smaller exhaled particles can infect people who inhale them, the newspaper said on Saturday.

Because those smaller particles can linger in the air longer, the scientists - who plan to publish their findings in a scientific journal this week - are urging WHO to update its guidance, the Times said.

"We are aware of the article and are reviewing its contents with our technical experts," WHO spokesman Tarik Jasarevic said in an email reply on Monday to a Reuters request for comment.

The extent to which the coronavirus can be spread by the so-called airborne or aerosol route - as opposed to by larger droplets in coughs and sneezes - remains disputed.

Any change in the WHO's assessment of the risk of transmission could affect its current advice on keeping one-metre physical distancing. Governments, which also rely on the agency for guidance policy, may also have to adjust public health measures aimed at curbing the spread of the virus.

"Especially in the last couple of months, we have been stating several times that we consider airborne transmission as possible but certainly not supported by solid or even clear evidence," Benedetta Allegranzi, the WHO's technical lead for infection prevention and control, was quoted as saying in the New York Times.

WHO guidance to health workers, dated June 29, says that SARS-CoV-2, the virus that causes Covid-19, is primarily transmitted between people through respiratory droplets and on surfaces.

But airborne transmission via smaller particles is possible in some circumstances, such as when performing intubation and aerosol-generating procedures, it says.

Medical workers performing such procedures should wear heavy-duty N95 respiratory masks and other protective equipment in an adequately ventilated room, the WHO says.

Officials at South Korea's Centers for Disease Control said on Monday they were continuing to discuss various issues about Covid-19, including the possible airborne transmission. They said more investigations and evidence were needed.

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Agencies
April 21,2020

The Lockdown is not a cure but a critical strategy to prevent the geographical spread of COVID-19.

While pandemics at this level involves actual life threatening situations for individual's or significant others in one's immediate circle, it envisages a marked disruption in routine life. Even after the pandemic has been contained and will come to pass; it's aftermath will leave a trailblazer which demands planning and implementation of a post pandemic reconstruction of society with potentially traumatic experiences varying in intensity, multiplicity and duration.

Degree of Trauma

It would do well for each one of us to realise that the pandemic is "potentially traumatic", since not everyone will experience COVID -19 as a traumatic event in their lives. Yet, there will be those who may develop post pandemic stress reactions, depression and related dysfunction and pathological reactions while still other exhibit healthy reactions to the same set of circumstances.

"Psychological reactions to the pandemic can be distilled into four distinct prototypical patterns, namely, Resilience, Recovery, Chronic and Delayed patterns which may vary in intensity, multiplicity, and duration. Resilient individual have an ability to bounce back from adversity and experience modest or little disruption in normal functioning and are able to maintain a relatively stable, healthy levels of psychological functioning even after enduring the pandemic. Recovery pattern is characterised by relatively rapid reduction in symptoms and return to normal functioning whereas chronic pattern is characterised by symptoms and dysfunction of a long duration," says Pune-based military psychologist Lt Col Dr Samir Rawat.

Challenges at the Individual and Community Levels

From a psychological perspective, post pandemic reconstruction would entail catering to the problems, concerns and needs of those adversely impacted by the COVID -19 with stress symptoms typically characterised by individual's experiencing an overwhelming trauma of the pandemic (for example, recurring nightmares/ breaking into a cold sweat, flashback of stressful events, increasing irritability, low frustration tolerance or emotional numbing).

It could also manifest in depressive symptoms which may result in lack of interest or diminished pleasure in activities and things which you earlier liked to do, feelings of worthlessness or even survivor guilt in case of a loss of a loved one due to COVID-19, fleeting thoughts of death and suicidal ideation. Physical symptoms, on the other hand could be a decrease in appetite, weight and sleep problems, inability to focus and lack of concentration.

Undoubtedly, the pandemic will cause a financial loss of varying magnitude to many, especially the marginalised and economically disadvantaged strata of daily wage earners; it will also lead to loss of jobs (already beginning to show), homelessness, occupational difficulties and new challenges in interpersonal relations at work and on the home front, besides physical health problems and psychological barriers with new norms of accepted social behaviour (social distancing, handshakes, an obsession for cleanliness to name a few).

Emotional battles

Many factors may influence whether individuals come out stronger and more resilient or surrender to the pandemic. Emotion Regulation is one such long term critical factor that can play an important role in contributing to varying degrees of adaptation with negative or positive outcomes. While we know that primary emotions are fear, anger, disgust, joy, anticipation, acceptance, sadness and surprise, other basic emotions include wonder, love, desire, joy, hatred, sadness, attachment, disgust, rage and even expectancy .

To be able to regulate these emotions and avoid negativity , especially on social media platforms is likely to increase efforts in emotion regulation which involves initiating, increasing or maintaining an emotional response.

This means by regulating or on the other hand by stopping, decreasing or avoiding an emotional response, that is, by down-regulating, depending on the individual's objectives and goals or his /her ability to regulate emotions in the valued and given direction.

"One of the best ways to regulate emotions is through cognitive restructuring wherein we change the way we think; after all it is not the event but the interpretation of the event which is perceived as stressful and finding meaning promotes resilience and reduces risk and vulnerability to stress," advises Dr Rawat.

Adding, "Clearly, we need to have a psychological plan to prevent, mitigate and minimise negative outcomes by post pandemic reconstruction of society at an individual and community level all over the country; this has to be integrated by all leaders across verticals in diverse domains."

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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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