Knowledge Update

​Johannesburg, Sep 10 (IANS) Researchers have developed a new heart valve replacement device that does not require advanced cardiac surgical facilities or sophisticated cardiovascular imaging and offers hope for the thousands of patients suffering from rheumatic heart disease.

Rheumatic heart disease is caused by rheumatic fever, which results from a streptococcal infection. Patients develop fibrosis of the heart valves, leading to valvular heart disease, heart failure and death. 

"Over the past decade heart valve surgery has been revolutionised by transcatheter aortic valve implantation (TAVI), where heart valves are replaced or repaired via a catheter, obviating the need for open heart surgery or a heart-lung machine," said lead author Jacques Scherman, Cardiac Surgeon at the University of Cape Town, South Africa. 

The team developed a novel TAVI device which is "non-occlusive", meaning that there is no need to stop blood circulating to the body with rapid ventricular pacing -- quick heart beats. 

The device is also "self-locating" and does not require sophisticated cardiac imaging for positioning.

Testing the device in a sheep model, the team found that the device was easy to use and positioned the valve correctly, and the procedure could be performed without rapid ventricular pacing.

"We showed that this new non-occlusive, self-locating TAVI delivery system made it easy to perform transcatheter aortic valve replacement," Scherman said. 

"Using tactile feedback the device is stabilised in the correct position within the aortic root during the implantation. It also has a temporary backflow valve to prevent blood leaking backwards into the ventricle during the implantation of the new valve," Scherman explained.

All these factors together allowed for a slow, controlled implantation compared to the currently available balloon expandable devices. 

Further, this simplified approach to transcatheter aortic valve replacement could be done in hospitals without cardiac surgery at a fraction of the cost of conventional TAVI. 

It has the potential to save the lives of the large numbers of rheumatic heart disease patients in need of valve replacement, the researchers said.

The findings were presented at the SA Heart Congress 2016, in Cape Town recently.

​London, Sep 8 (IANS) An international team of researchers has found that a stellar system classified as a globular cluster for the 40-odd years since its detection actually has properties uncommon for a globular cluster that make it the ideal candidate for a living fossil from the early days of the Milky Way.

The cluster, known as Terzan 5 -- 19,000 light-years from Earth -- harbours stars of hugely different ages -- an age-gap of roughly seven billion years -- and bridges the gap in understanding between our galaxy's past and its present, the study said.

"Such galactic fossils allow astronomers to reconstruct an important piece of the history of our Milky Way," explained lead author of the study Francesco Ferraro from University of Bologna in Italy.

While the properties of Terzan 5 are uncommon for a globular cluster, they are very similar to the stellar population which can be found in the galactic bulge, the tightly packed central region of the Milky Way. 

These similarities could make Terzan 5 a fossilised relic of galaxy formation, representing one of the earliest building blocks of the Milky Way.

"Terzan 5 could represent an intriguing link between the local and the distant Universe, a surviving witness of the Galactic bulge assembly process," Ferraro said.

The team scoured data from the Advanced Camera for Surveys and the Wide Field Camera 3 on board Hubble, as well as from a suite of other ground-based telescopes. 

They found compelling evidence that there are two distinct kinds of stars in Terzan 5 which not only differ in the elements they contain, but have an age-gap of roughly seven billion years.

The ages of the two populations indicate that the star formation process in Terzan 5 was not continuous, but was dominated by two distinct bursts of star formation. 

"This requires the Terzan 5 ancestor to have large amounts of gas for a second generation of stars and to be quite massive. At least 100 million times the mass of the Sun," co-author of the study Davide Massari from National Institute for Astrophysics (INAF) , Italy.

Its unusual properties make Terzan 5 the ideal candidate for a living fossil from the early days of the Milky Way, said the study published in the Astrophysical Journal.

Somehow Terzan 5 has managed to survive being disrupted for billions of years, and has been preserved as a remnant of the distant past of the Milky Way.

The researchers believe that this discovery paves the way for a better and more complete understanding of galaxy assembly. 

New York, Sep 8 (IANS) Activities like playing video games or tennis may help enhance your memory, a study has found.

Attention-grabbing experiences release memory-enhancing chemicals in brain, helping to store memories that occur just before or soon after the experience, the study mentioned.

"Activation of the locus coeruleus (part of the brainstem) increases our memory of events that happen at the time of activation and may also increase the recall of those memories at a later time," said Robert Greene, Professor at the Peter O'Donnell Jr. Brain Institute at UT Southwestern Medical Center's Texas Institute for Brain Injury and Repair, at Dallas in Texas.

The study, published in the journal Nature explains at the molecular level why people tend to remember certain events in their lives with particular clarity as well as unrelated details surrounding those events.

The latest study established that dopamine in the brain can be naturally activated through behavioural actions and that these actions enhance memory retention.

The study tested 120 mice to establish a link between locus coeruleus (LC) neurons and neuronal circuits of the hippocampus -- the region of the brain responsible for recording memories -- that receive dopamine from the LC.

One part of the research involved putting the mice in an arena to search for food hidden in sand that changed location each day. 

The study found that the mice that were given a chance to explore an unfamiliar floor surface 30 minutes after being trained to remember the food location did better in remembering where to find the food the next day.

Researchers correlated this memory enhancement to a molecular process in the brain by injecting the mice with a genetically encoded light-sensitive activator called channelrhodopsin. 

This sensor allowed them to selectively activate dopamine-carrying neurons of the locus coeruleus that go to the hippocampus and to see first-hand which neurons were responsible for the memory enhancement.

They found that selectively activating the channelrhodopsin-labeled neurons with blue light (a technique called optogenetics) could substitute for the novelty experience as a memory enhancer in mice. 

They also found that this activation could cause a direct, long-lasting synaptic strengthening -- an enhancement of memory-relevant communication occurring at the junctions between neurons in the hippocampus. This process can mediate improvement of learning and memory.

"Some next steps include investigating how big an impact this finding can have on human learning, whether it can eventually lead to an understanding of how patients can develop failing memories, and how to better target effective therapies for these patients," Greene added.

New York, Sep 8 (IANS) Risk of death from sudden loss of heart function is significantly greater in patients with high thyroid hormone levels, according to a study.

"Our results indicate that thyroid hormone levels may be useful for assessing risk to prevent sudden cardiac death," said Layal Chaker, researcher at the Erasmus University Medical Center, at Rotterdam in the Netherland, in the study, published in the journal Circulation.

Although the link between abnormal levels of thyroid hormone and cardiovascular disease is well established, the hormone's relationship with sudden cardiac death is unclear.

Researchers analysed 10,318 patients with an average age of 65 and more than half were women for the study and linked the association of thyroid-stimulating hormone and free thyroxine thyroid hormone levels in blood samples with sudden cardiac deaths listed on medical records and death certificates.

They found that participants with free thyroxine hormone levels at the high end of the normal range were 2.5 times more likely to die of sudden cardiac death, compared to patients with levels at the lower end.

The ten-year risk of sudden cardiac death was four times greater among patients with higher free thyroxine levels compared to those with lower levels.

The increased risk persisted even after controlling for other risk factors such as high cholesterol and high blood pressure.

"The study suggests more caution is warranted in the treatment of thyroid hormone replacement. Replacement therapy is often aimed at the high normal range which carries a risk of over-treatment," Chaker added. 

​London, Sep 7 (IANS) Aimed at making the task of predicting renewable output easier for the industry, researchers have created an interactive web tool to estimate the quantum of energy that could be generated by wind or solar farms at any location.

The researchers have already used the tool, called Renewables.ninja, to estimate current Europe-wide solar and wind output.

"Renewables.ninja has already allowed us to answer important questions about the current and future renewable energy infrastructure across Europe and in the UK, and we hope others will use it to further examine the opportunities and challenges for renewables in the future," said Stefan Pfenninger from ETH Zurich in Switzerland.

To test the model, Pfenninger and Iain Staffell from College London used the tool to estimate the productivity of all wind farms planned or under construction in Europe for the next 20 years. 

Wind and solar energies have a strong dependence on weather conditions, and these can be difficult to integrate into national power systems that requires consistency. If there is excess power generated by all energy sources, then some supplies have to be turned off.

Currently, wind and solar power generators are the easiest to switch on and off, so they are often the first to go, meaning the power they generate can be wasted.

Renewables.ninja uses 30 years of observed and modelled weather data from organisations such as NASA to predict the wind speed likely to influence turbines and the sunlight likely to strike solar panels at any point on the Earth during the year, the researchers said in a paper published in the journal Energy.

These figures are combined with manufacturer's specifications for wind turbines and solar panels to give an estimate of the power output that could be generated by a farm placed at any location.

​Johannesburg, Sep 7 (IANS) Scientists, including researchers from India, have predicted the existence of a new boson that might aid in the understanding of dark matter in the universe.

Using data from a series of experiments that led to the discovery of Higgs boson at the European Organisation for Nuclear Research (CERN) in 2012, the team led by the High Energy Physics Group (HEP) of the University of Witwatersrand in Johannesburg established what they call "Madala boson".

The experiment was repeated in 2015 and 2016, after a two-and-half years' shut-down of the Large Hadron Collider (LHC) at CERN.

The data reported by the LHC experiments in 2016 have corroborated the features in the data that triggered the Madala hypothesis in the first place.

The Wits Madala project team consists of approximately 35 young South African and African students and researchers, along with theorists such as Professor Alan Cornell and Dr Mukesh Kumar.

Some of these scientists include Dr Deepak Kar and Dr Xifeng Ruan, two new academic staff in the group, who have years of expertise at the LHC.

"Based on a number of features and peculiarities of the data reported by the experiments at the LHC and collected up to the end of 2012, the Wits HEP group in collaboration with scientists in India and Sweden formulated the Madala hypothesis," says Professor Bruce Mellado, team leader of the HEP group at Wits, in a statement.

The hypothesis describes the existence of a new boson and field, similar to the Higgs boson.

Boson is a subatomic particle, such as a photon, which has zero or integral spin and follows the statistical description given by theoretical physicists Satyendra Nath Bose and Albert Einstein.

However, where the Higgs boson in the Standard Model of Physics only interacts with known matter, the Madala boson interacts with dark matter, which makes about 27 per cent of the universe.

The theory that underpins the understanding of fundamental interactions in nature in modern physics is referred to as the Standard Model of Physics.

With the discovery of the Higgs boson at the LHC in 2012, for which the Nobel Prize in Physics was awarded in 2013, the Standard Model of Physics is now complete.

However, this model is insufficient to describe a number of phenomena such as dark matter.

"With the Madala hypothesis predictions of striking signatures are made, that is being pursued by the young scientists of the Wits HEP group," the authors noted.

​New York, Sep 7 (IANS) As commercial speech recognition systems are derived largely from adult speech, Disney researchers have developed a new speech technology system that could make playing certain video games or interactions with robots more fun for kids.

The new technology sorts through the overlapping speech, social side talk and creative pronunciations of young children to help them better control a video game called Mole Madness that require kids to say say just two words - "jump" and "go".

The multi-keyword-spotting system, developed by Disney Research, could make it possible to design any number of speech-based game or entertainment applications for children, including interactions with robots, the study said.

"Speech recognition applications have become increasingly commonplace as the technology has matured, but understanding what kids say when they play remains difficult," said Jessica Hodgins, vice president at Disney Research - an international network of research labs in US.

"Kids don't necessarily pronounce words quite like adults and when they are playing together, as they like to do, they often engage in side banter, or exclamations of excitement, or simply talk over each other," Lehman said. 

In the cooperative Mole Madness - a two-player video game, kids needed to say just two words - "jump" and "go" while moving an animated mole through its environment, gathering rewards as they avoid obstacles. 

During game play, the players often say their commands simultaneously. In other cases, they make statements to each other, such as "Don't say 'go' yet," that can be misinterpreted by the system. 

"This technology can be reproduced with other vocabulary, allowing designers and developers to build novel children's applications that use limited speech as an input method," Lehman said.

The findings were presented at the Workshop on Child Computer Interaction in San Francisco.

​London, Sep 6 (IANS) Genetic factors are responsible for prompting individuals with attention deficit hyperactivity disorder (ADHD) to develop alcohol dependence as well as indulge in binge eating, finds a study.

Apart from children, nearly five per cent of the global adult population is also suffering from ADHD, the study said, adding that both alcohol dependence and binge eating are more common in adults with ADHD than in the general population. 

The research suggests that certain individuals inherit a susceptibility for both ADHD symptoms and dependency disorders or binge eating, thus these problems must be treated in parallel, said Andrea Johansson Capusan from Linkoping University in Sweden.

"When treating adults who come with dependency disorder or substance-abuse behaviour, it's important to remember that ADHD is very common in these patients. And conversely-it's important to treat ADHD early in order to prevent alcohol dependence and binge eating later in life," Capusan added.

For the study, the researchers examined more than 18,000 twin pairs aged between 20 and 46 years.

They compared identical twins, who share 100 per cent of their genes, with fraternal twins, whose genetic makeups are no more similar to each other than any pair of siblings. 

Twin pairs grow up in the same environment, but are affected by individual environmental factors, such as diseases and their circles of friends, the researchers said. 

For ADHD symptoms and alcohol dependence, 64 per cent of the overlap was explained by common genetic factors. 

The remaining variance was accounted for by environmental factors specific for each twin with no sex differences for the overlap. 

Similarly, 91 per cent of the association between ADHD symptoms and binge-eating behaviour was explained by common genetic factors. 

The study helped researchers to determine whether the correlation between different conditions can best be explained by a person's genetic background giving higher susceptibility to a condition, or whether environmental factors are significant. 

Since heredity plays such a large role, it is important that ADHD is treated at an early stage, and that measures are taken to prevent individuals developing these disorders later in life, the researchers concluded.​

New York, Sep 7 (IANS) While electric fans keep young adults cooler by increasing the evaporation of sweat, they may, surprisingly, have the opposite effect for those above the age of 60, suggests new research.

The heart rate and internal temperature of seniors exposed to 41.6 degree Celsius temperatures and increasing humidity levels climbed even higher when they tried to cool off with fans -- instead of falling as expected, according to study findings reported in the journal JAMA.

"Although differences were small, the cumulative effect could become clinically important during prolonged heat exposure, such as during extreme heat waves," said Craig Crandall, Professor of Internal Medicine at University of Texas Southwestern Medical Center in the US.

"We know that fans keep young adults cooler by increasing the evaporation of sweat," Crandall said. 

"We surmise that age-related impairments in sweating capacity make fans an ineffective means of cooling for the elderly during exceptionally hot days, and may, in fact, increase thermal and cardiac strain," Crandall noted.

Researchers studied the physiological responses of a small group of elderly patients in a high-heat, high-humidity environment. 

Participants between the ages of 60 and 80 were observed for approximately two hours in a room with the temperature set at a sweltering 41.6 degrees Celsius and a humidity level that was gradually increased from 30 per cent to 70 per cent. 

Not surprisingly, both heart rate and internal body temperature rose as the humidity level in the room rose. 

The eight individuals in the study were tested under those conditions without a fan and, on a separate occasion, with an electric fan. 

Unexpectedly, the participants' heart rates were 10 beats per minute higher and their internal temperatures marginally higher when a fan was part of the experimental environment. 

Although these findings suggest that fan use may be counterproductive for seniors during heat waves, the investigators propose that fan use may still be beneficial under less extreme environmental conditions, though this needs to be confirmed.

New York, July 31 (IANS) In their bid to design new bio-materials that promote tissue regeneration, scientists have identified how inflammation, when precisely controlled, is crucial for bone repair.

The findings showed that a new type of ceramic scaffold causes inflammatory cells to behave in a way that is more regenerative than scaffolds that are currently used clinically.

The reason can be attributed to macrophages -- swallowing white blood cells that digest foreign particles, the researchers said.

"We wanted to know why these scaffolds were successful and to understand the contributions of macrophages to that process," said Kara Spiller, Associate Professor Drexel University, in Pennsylvania, the US.

The findings showed that the new ceramic scaffolds caused macrophages to transform into an M2c phenotype, meaning they express genes associated with re-modelling.

This behaviour was not seen in the scaffolds that have been approved to be used in humans.

Further, the study also found that macrophages must be in direct contact with the scaffold in order to regenerate tissue.

"The macrophages degrade the scaffolds and shape them into something new," Spiller said.

Determining why certain scaffolds are successful in re-growing bone will ultimately help biomedical engineers design other types of scaffolds and new drug delivery strategies to promote healing in other areas of the body, the researchers concluded in the paper published in the Journal of the Royal Society Interface.​