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
February 4,2020

Boston, Feb 4: Practising yoga may increase levels of a messenger molecule involved in regulating brain activity, and completing one yoga class per week may maintain elevated levels of this chemical, according to a study which may lead to better ways of mitigating depressive symptoms.

The study, published in the Journal of Alternative and Complementary Medicine, assessed a group of 30 clinically depressed patients who were randomly divided into two groups.

According to the researchers, including those from Boston University in the US, both groups engaged in coherent breathing, and Iyengar yoga -- a form of hatha yoga, developed by B. K. S. Iyengar, emphasising on detail, precision, and alignment in the performance of yoga postures.

The only difference between the groups, the scientists said, was the number of 90 minute yoga sessions, and home sessions in which each group participated.

Over three months, they said, the high-dose group (HDG) was assigned three sessions per week, while the low-intensity group (LIG) engaged in two sessions per week.

The participants underwent magnetic resonance imaging (MRI) scans of their brain before the first and after the last yoga session, and also completed a clinical depression scale to monitor their symptoms, the study noted.

Results of the study revealed that both groups had improvement in depressive symptoms after three months.

Their MRI analysis showed that levels of the brain messenger molecule GABA were elevated after three months of yoga, as compared to the levels before starting yoga.

According to the study, this increase was found for approximately four days after the last yoga session, but the rise was no longer observed after about eight days.

"The study suggests that the associated increase in GABA levels after a yoga session are 'time-limited' similar to that of pharmacologic treatments such that completing one session of yoga per week may maintain elevated levels of GABA," explained study co-author Chris Streeter from Boston University.

Providing evidence-based data may help in getting more individuals to try yoga as a strategy for improving their health and well-being, the scientists said.

"A unique strength of this study is that pairing the yoga intervention with brain imaging provides important neurobiological insight as to the 'how' yoga may help to alleviate depression and anxiety," said study co-author Marisa Silveri from Harvard University.

In this study, we found that an important neurochemical, GABA, which is related to mood, anxiety, and sleep, is significantly increased in association with a yoga intervention," Silveri said.

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Dr G K Sudhakar Reddy
August 4,2020

Being overweight or obese is now recognised as a serious cause of ill health and disability. There is a significant positive association between orthopaedic disorders and the level of obesity causing pain, deformity and difficulty in walking.

Excess body weight accumulation increases pressure on joints, particularly the hips, knees and ankles.

Here are a few type of  arthritis:

Osteoarthritis

It is a condition of damage/ wear and tear of the joint lining or cartilage. Obesity triggers this by loading excessive weight on the weight bearing joints like the knee and the hip. 

Knee Osteoarthritis

This is the most common arthritis especially in the Indian subcontinent.

While walking, an individual exerts 3 to 6 times pressure that of the body weight on the weight-bearing knee joint, which means in an obese with excess body weight, larger forces are exerted, which lead to higher risk of deterioration of cartilage.

In addition, there are excessive fat tissues that produce hormones and other factors that affect the joint cartilage metabolism and cause inflammation of the joints giving rise to joint pathology.  Leptin is one of the hormones causing knee osteoarthritis. 

Hip osteoarthritis

The force exerted across the hip is 3 times that of body weight. Hip osteoarthritis is caused by factors such as joint injury, increasing age and being overweight.    

Hand osteoarthritis

The observation that obese individual has a higher risk in having hand osteoarthritis has led to a hypothesis that the metabolic effect produced by fat tissue is the underlying factor. 

Osteoporosis

It is a progressive bone condition of decrease in bone mass and density (Bone Mineral Density or BMD) which can lead to an increased risk of fracture. Recent research suggests that obesity may accelerate bone loss. It is the amount of muscle mass which is seen in an active person, which accounts for bone strengthening effects and not due to the fat seen in a heavy person.

Low back pain

Low back pain from degenerative disc disease of the lumbar spine is one of the most disabling conditions in the community and overweight and obesity have the strongest association with seeking care for low back pain.

Managing Hip and Knee Osteoarthritis

Life style changes

If one is overweight, try to lose weight by doing more physical activity and eating a healthier diet. Regular exercise keeps you active and mobile and builds up muscle, thereby strengthening the joints and can improve symptoms. 

Pain Killers

Painkillers help with pain and stiffness for short term. They don’t affect the arthritis itself and won’t repair the damage to your joint. Creams and gels can be applied directly onto painful joints.

Nutritional Supplements

Glucosamine and chondroitin are nutritional supplements. Animal studies have found that glucosamine can both delay the breakdown of and repair damaged cartilage. However, there is insufficient evidence to support the use of glucosamine in humans and one can expect only a mild-to-moderate reduction in pain

Joint injections

If pain from osteoarthritis is severe joint steroid injections are injected into the joints that can reduces swelling and pain. The injections can start working within a day or so and may improve pain for several weeks or months. 

Hyaluronic acid injections, which help to lubricate your knee joint also give short term relief. In early stages. Stem cell treatment or cartilage regeneration procedures are being tried in young people with small defects, however it is still experimental and lacks long term evidence.

Surgery

May be recommended if you have severe pain or mobility problems.

Arthroscopy

If one has frequent painful locking/stiffening episodes especially in the knee joint, an operation to wash out loose fragments of bone and other tissue as joint can be performed by a minimally invasive key hole procedure called Arthroscopy.

Arthrodesis

If hip or knee replacement is not suitable, especially in young people who do heavy manual work, one can consider an operation known as an arthrodesis, which fuses your joint in a permanent position. This means that your joint will be stronger and much less painful, although you will no longer be able to move it.

Osteotomy

In young, active people in whom a knee joint replacement would fail due to excessive use one can consider an operation called an osteotomy. This involves adding or removing a small section of bone either above or below your knee joint.  This helps realign your knee so your weight is no longer focused on the damaged part of your knee. An osteotomy can relieve your symptoms of osteoarthritis, although you may still need knee replacement surgery eventually as you grow old

Joint replacement surgery

Joint replacement therapy is most commonly carried out to replace hip and knee joints. It involves replacing a damaged, worn or diseased joint with an artificial joint made of special plastics and metal.

For most people, a replacement hip or knee will last for at least 20 years, especially if it is cared for properly and not put under too much strain.

Dr G K Sudhakar Reddy is a Sr Consultant Orthopaedic Surgeon at Citizens Speciality Hospitals, Hyderabad

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Agencies
June 27,2020

After admitting that the world may have a COVID-19 vaccine within one year or even a few months earlier, the World Health Organisation (WHO) on Friday said that UK-based AstraZeneca is leading the vaccine race while US-based pharmaceutical major Moderna is not far behind.

WHO Chief Scientist Soumya Swaminathan stated that the AstraZeneca's coronavirus vaccine candidate is the most advanced vaccine currently in terms of development.

"I think AstraZeneca certainly has a more global scope at the moment in terms of where they are doing and planning their vaccine trials," she told the media.

AstraZeneca's Covid-19 vaccine candidate developed by researchers from the Oxford University will likely provide protection against the disease for one year, the British drug maker's CEO told Belgian radio station Bel RTL this month.

The Oxford University last month announced the start of a Phase II/III UK trial of the vaccine, named AZD1222 (formerly known as ChAdOx1 nCoV-19), in about 10,000 adult volunteers. Other late-stage trials are due to begin in a number of countries.

Last week, Swaminathan had said that nearly 2 billion doses of the COVID-19 vaccine would be ready by the end of next year.

Addressing the media from Geneva, she said that "at the moment, we do not have a proven vaccine but if we are lucky, there will be one or two successful candidates before the end of this year" and 2 billion doses by the end of next year.

Scientists predict that the world may have a COVID-19 vaccine within one year or even a few months earlier, said the Director-General of the World Health Organization even as he underlined the importance of global cooperation to develop, manufacture and distribute the vaccines.

However, making the vaccine available and distributing it to all will be a challenge and will require political will, WHO chief Tedros Adhanom Ghebreyesus said on Thursday during a meeting with the European Parliament's Committee for Environment, Public Health and Food Safety.

One option would be to give the vaccine only to those who are most vulnerable to the virus.

There are currently over 100 COVID-19 vaccine candidates in various stages of development.

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