22nd Jul 2014, 12:24 AM #1291
Re: Health Bulletin
Learning to read continues beyond fourth grade, finds new study
One of the most popular theories among parents and teachers is that children stop learning to read and start reading to learn when they reach class four. But a new Dartmouth College study in the journal Developmental Science tested the theory by analyzing brain waves and found that fourth-graders do not experience a change in automatic word processing. Instead, some types of word processing become automatic before fourth grade, while others don't switch until after fifth.
Automatic word processing is the brain's ability to determine whether a group of symbols constitutes a word within milliseconds, without the brain's owner realizing the process is taking place.
The findings mean that teachers at all levels of elementary school must think of themselves as reading instructors, said the study's author Donna Coch, associate professor at Dartmouth.
"Until now, we lacked neurological evidence about the supposed fourth-grade shift," said Coch, also principal investigator for Dartmouth's Reading Brains Lab. "The theory developed from behavioral evidence, and as a result of it, some teachers in fifth and sixth grade have not thought of themselves as reading instructors. Now we can see from brain waves that students in those grades are still learning to process words automatically; their neurological reading system is not yet adult-like."
To test how automatic word processing develops, Coch placed electrode caps on the heads of third-, fourth-, and fifth-graders, as well as college students. She had her test subjects view a screen that displayed a mix of real English words (such as "bed"), pseudo-words (such as "bem"), strings of letters (such as "mbe"), and strings of meaningless symbols one at a time. The setup allowed her to see how the subjects' brains reacted to each kind of stimulus within milliseconds. In other words, she could watch their automatic word processing.
Next, Coch gave the participants a written test, in which they were asked to circle the real words in a list that also contained pseudo-words, strings of letters, and strings of meaningless symbols. This task was designed to test the participants' conscious word processing, a much slower procedure.
Interestingly, most of the 96 participants got a nearly perfect score on the written test, showing that their conscious brains knew the difference between words and non-words.
However, the electrode cap revealed that only the college students processed meaningless symbols differently than real words. The third-, fourth-, and fifth-graders' brains reacted to the meaningless symbols the same way they reacted to common English words.
"This tells us that, at least through the fifth grade, even children who read well are letting stimuli into the neural word processing system that more mature readers do not," Coch said. "Their brains are processing strings of meaningless symbols as if they were words, perhaps in case they turn out to be real letters. In contrast, by college, students have learned not to process strings of meaningless symbols as words, saving their brains precious time and energy."
The phenomenon is evidence that young readers do not fully develop automatic word processing skills until after fifth grade, which contradicts the fourth-grade reading shift theory.
The brain waves also showed that the third-, fourth-, and fifth-graders processed real words, pseudo-words, and letter strings similarly to college students, suggesting that some automatic word processing begins before the fourth grade, and even before the third grade, also contradicting the reading shift theory.
"There is value to the theory of the fourth grade shift in that it highlights how reading skills and abilities develop at different times," Coch said. "But the neural data suggest that teachers should not expect their fourth-graders, or even their fifth-graders, to be completely automatic, adult-like readers."
22nd Jul 2014, 03:46 PM #1292
Re: Health Bulletin
Larks' are unethical at night, 'owls' in morning, says study
Early risers are more likely to cheat and behave unethically in the night hours, scientists, including one of Indian-origin, have found. Researchers have found that early-rising "larks" and late-night "owls" had different levels of honesty depending on the time of day.
The study, by Sunita Sah, research fellow at Harvard University, and colleagues examined the behaviour of almost 200 people — with the subjects taking part in problem-solving tests and games without realising that it was their honesty that was being measured. The study examined the relationship between ethical decision making and people's "chronotype" — which is when individuals are most likely to want to be asleep or when they have more energy.
It found a significant link between people being more likely to be honest when it fitted in with their chronotype, 'BBC News' reported.
This meant that the early-rising "larks" were more ethical in the morning — and the "owls" were more likely to be honest at night.
Researchers found that the level of dishonesty was found to be heightened when people were outside of their preferred time of day. In morning, evening people are more unethical than morning people, the study found.
22nd Jul 2014, 04:10 PM #1293
Re: Health Bulletin
Tech to map life's imprint on DNA
Wonder how your environment is affecting your DNA? New technique can tell! Researchers have developed a powerful new single-cell technique to help investigate how the environment affects our development and the traits we inherit from our parents. The technique can be used to map all of the 'epigenetic marks' on the DNA within a single cell.
This single-cell approach will boost understanding of embryonic development, could enhance clinical applications like cancer therapy and fertility treatments, and has the potential to reduce the number of mice currently needed for this research.
'Epigenetic marks' are chemical tags or proteins that mark DNA and act as a kind of cellular memory. They do not change the DNA sequence but record a cell's experiences onto the DNA, which allows cells to remember an experience long after it has faded.
Placing these tags is part of normal development; they tell genes whether to be switched on or off and so can determine how the cell develops. Different sets of active genes make a skin cell different from a brain cell, for example. However, environmental cues such as diet can also alter where epigenetic tags are laid down on DNA and influence an organism's long-term health. "The ability to capture the full map of these epigenetic marks from individual cells will be critical for a full understanding of early embryonic development, cancer progression and aid the development of stem cell therapies," Dr Gavin Kelsey, from the
Babraham Institute, UK said. "Epigenetics research has mostly been reliant on using the mouse as a model organism to study early development.
"Our new single-cell method gives us an unprecedented ability to study epigenetic processes in human early embryonic development, which has been restricted by the very limited amount of tissue available for analysis," said Kelsey.
The research, published in journal Nature Methods, offers a new singlecell technique capable of analysing DNA methylation one of the key epigenetic marks — across the whole genome. The method treats the cellular DNA with a chemical called bisulphite. Treated DNA is then amplified and read on high — throughput sequencing machines to show up the location of methylation marks and the genes being affected.
22nd Jul 2014, 09:45 PM #1294
Re: Health Bulletin
Breakthrough in fight against AIDS, scientists 'delete' HIV from human cells
Scientists have for the first time ever "deleted" HIV from human cells, marking a major breakthrough in fight against AIDS.
Once HIV conquers a human cell, it stays there forever. The virus inserts its deadly genome permanently into the victims' DNA, forcing patients to be hooked on drugs for life.
But now, for the first time, researchers have found a way to eliminate latent HIV-1 virus from human cells — and this could be a cure for other latent infections.
Now, a team of Temple University School of Medicine researchers has designed a way to snip out the integrated HIV-1 genes for good.
"This is one important step on the path toward a permanent cure for AIDS," said Kamel Khalili, professor and chair of the department of Neuroscience at Temple.
Khalili led the work which marks the first successful attempt to eliminate latent HIV-1 virus from human cells.
"It's an exciting discovery, but it's not yet ready to go into the clinic. It's a proof of concept that we're moving in the right direction," added Khalili.
When deployed, a combination of a DNA-snipping enzyme called a nuclease and a targeting strand of RNA called a guide RNA (gRNA) hunt down the viral genome and excise the HIV-1 DNA.
From there, the cell's gene repair machinery takes over, soldering the loose ends of the genome back together — resulting in virus-free cells.
"Since HIV-1 is never cleared by the immune system, removal of the virus is required in order to cure the disease," said Khalili, whose research focuses on the neuropathogenesis of viral infections. The same technique could theoretically be used against a variety of viruses, he said.
The research shows that these molecular tools also hold promise as a therapeutic vaccine; cells armed with the nuclease-RNA combination proved impervious to HIV infection.
Worldwide, more than 33 million people have HIV.
Although highly active antiretroviral therapy (HAART) has controlled HIV-1 for infected people in the developed world over the last 15 years, the virus can rage again with any interruption in treatment.
Even when HIV-1 replication is well controlled with HAART, the lingering HIV-1 presence has health consequences.
"The low level replication of HIV-1 makes patients more likely to suffer from diseases usually associated with aging," Khalili said. These include cardiomyopathy — a weakening of the heart muscle — bone disease, kidney disease, and neurocognitive disorders. "These problems are often exacerbated by the toxic drugs that must be taken to control the virus," Khalili added.
Researchers based the two-part HIV-1 editor on a system that evolved as a bacterial defense mechanism to protect against infection, Khalili said.
Dr Khalili's lab engineered a 20-nucleotide strand of gRNA to target the HIV-1 DNA and paired it with Cas9. The gRNA targets the control region of the gene called the long terminal repeat (LTR). LTRs are present on both ends of the HIV-1 genome. By targeting both LTRs, the Cas9 nuclease can snip out the 9,709-nucleotides that comprise the HIV-1 genome.
To avoid any risk of the gRNA accidentally binding with any part of the patient's genome, the researchers selected nucleotide sequences that do not appear in any coding sequences of human DNA, thereby avoiding off-target effects and subsequent cellular DNA damage.
The editing process was successful in several cell types that can harbor HIV-1, including microglia and macrophages, as well as in T-lymphocytes.
"T-cells and monocytic cells are the main cell types infected by HIV-1, so they are the most important targets for this technology," Khalili said.
The HIV-1 eradication approach faces several significant challenges before the technique is ready for patients, Khalili said.
The researchers must devise a method to deliver the therapeutic agent to every single infected cell. Finally, because HIV-1 is prone to mutations, treatment may need to be individualized for each patient's unique viral sequences.
"We are working on a number of strategies so we can take the construct into preclinical studies," Khalili said. "We want to eradicate every single copy of HIV-1 from the patient. That will cure AIDS. I think this technology is the way we can do it".
23rd Jul 2014, 01:39 PM #1295
Re: Health Bulletin
Scientists discover new genes linked to schizophrenia
The biggest ever study of its kind has discovered more than 100 genes that play some kind of role in the development of schizophrenia, one of the most common psychiatric disorders.
As part of a multinational, collaborative effort, 300 scientists in 35 countries helped identify the locations in the human genome associated with the risk of developing the illness. The findings point to biological mechanisms and pathways that may underlie schizophrenia, and could lead to new approaches to treating the disorder, which has seen little innovation in drug development in more than 60 years.
Schizophrenia, which affects about one in every 100 people, is characterized by hallucinations, delusions and disordered thinking and often emerges in the teens and early 20s.
The discovery, scientists say, will provide vital new clues in understanding what causes the condition and will kick-start the search for new treatments.
"We've been able to detect genetic risk factors on a huge and unprecedented scale and shed new light on the biological cause of the condition," said research leader Michael O' Donovan of Cardiff University School of Medicine.
Examining 80,000 samples from schizophrenia patients and healthy volunteers worldwide, the study found 108 specific locations in the human genome linked to schizophrenia, 83 of which were entirely new. As the authors had expected, the study implicates genes expressed in brain tissue but it also found genes associated with the illness were particularly active in the immune system.
The research was published in the journal 'Nature'.
"These remarkable findings were only made possible through a global collaboration," said Professor Sir Mike Owen, director of Cardiff University's MRC Centre for Neuropsychiatric Genetics and Genomics. "Detecting biological risk factors on this scale shows that schizophrenia can be tackled by the same approaches that have already transformed outcomes for people with other diseases. We now believe they can also do so for schizophrenia which has, until now, been so poorly understood."
Owen said the key challenge now was to translate the new insights into new diagnostic tools and novel treatments for patients and "finally put an end to the 60-year-wait for new treatments for sufferers worldwide".
23rd Jul 2014, 01:47 PM #1296
Re: Health Bulletin
Doctors remove part of girl's brain to stop seizures
Can half a brain be better than a whole one? That proved to be the case for eight-year-old Samia Sultana from Bangladesh, who was suffering from a rare neurological disease which caused severe seizures and other complications.
Doctors at a city hospital gave her a fresh lease of life by performing a challenging surgery, in which they removed a portion of her brain and de-wired some portions that were causing seizures. The girl, who could barely talk or swallow food three months ago, is now able to talk, walk and lead a normal life.
Samia was leading a normal life till October 2013 when she started feeling that her right hand and right leg were moving on their own without her control. Doctors in a hospital in Bangladesh diagnosed her condition as rheumatic chorea. Soon, she started getting epileptic attacks. An MRI scan showed that the child had a swelling on her left brain which doctors assumed was a tumor.
Samia was brought to India and admitted in a hospital in Chennai in February, but her condition did not improve. Moreover, her epileptic attacks became more frequent, which affected her speech and mobility. In April, she developed a lung infection and had to be kept on a ventilator. In mid-April, when her condition worsened, she was brought to Fortis Malar Hospitals.
"We found that she was suffering from Rasmussen's encephalitis, a rare neurological disease. It is characterized by frequent and severe seizures, loss of motor skills and speech, paralysis on one side of the body, inflammation of the brain and dementia," said neurologist Dr Dinesh Nayak. He said the disease mimics symptoms of other problems like brain tumour and displegia, which makes it difficult to diagnose. "Her left side of the brain was damaged. In adults, this would cause irreversible damage to one's ability to learn, remember and speak languages, a function which is controlled by the left side of the brain. But since she was a child, her right side took over that function," he said.
When medication did not help, a complicated surgical procedure called hemispherectomy was performed. "In this, the damaged half of the brain is disconnected from the good half. It is reserved for extreme cases which cannot be treated by medication or other less invasive surgeries," said Dr Nayak. The procedure lasted for six hours. "The seizures stopped immediately after the surgery. The child was on ventilator for three weeks after surgery and now she is able to talk and walk," the doctor said.
24th Jul 2014, 03:05 PM #1297
Re: Health Bulletin
Effectiveness of paracetamol questioned by researchers
In a surprising finding, paracetamol, which has been the world's most recommended first-line pain killer for acute low-back pain, has been found to be no better than a dud.
Researchers will announce on Thursday in the world's leading medical journal The Lancet that paracetamol is no better than placebo at speeding recovery from acute episodes of lower back pain or improving pain levels, function, sleep or quality of life.
This is the first large randomised trial to compare the effectiveness of paracetamol with placebo for low-back pain and questions the universal endorsement of paracetamol as the first choice painkiller for low-back pain.
Lower back pain — a common phenomenon among Indians — has been found to be the leading cause of years lived with disability (YLD) globally.
The Global Disease Burden study showed that lower back pain caused 83.1 million YLDs across the globe in 2010.
National clinical guidelines universally recommend paracetamol as the first choice analgesic for acute low-back pain, despite the fact that no previous studies have provided robust evidence that it is effective in people with low-back pain.
The paracetamol for Low-Back Pain Study (PACE) randomly assigned 1652 individuals (average age 45 years) with acute low-back pain from 235 primary care centres in Sydney, to receive up to four weeks of paracetamol in regular doses (three times a day; equivalent to 3990 mg per day), paracetamol as needed (maximum 4000 mg per day), or placebo. All participants were followed-up for 3 months.
No differences in the number of days to recovery were found between the treatment groups—median time to recovery was 17 days in the regular paracetamol group, 17 days in the as needed paracetamol group, and 16 days in the placebo group. Paracetamol also had no effect on short-term pain levels, disability, function, sleep quality, or quality of life. The number of participants reporting adverse events was similar between the groups.
"Simple analgesics such as paracetamol might not be of primary importance in the management of acute lower back pain", said lead author Dr Christopher Williams from the George Institute for Global Health at the University of Sydney in Australia. "The results suggest we need to reconsider the universal recommendation to provide paracetamol as a first-line treatment for low-back pain, although understanding why paracetamol works for other pain states but not low-back pain would help direct future treatments".
He adds, "In view of the quick timeframe in which participants in our trial improved compared with other cohorts, it would be interesting to see whether advice and reassurance might be a more effective than pharmacological strategies for acute episodes of low-back pain".
25th Jul 2014, 01:24 PM #1298
Re: Health Bulletin
Apollo Hospitals launches Strand's clinical genomic tests
Apollo Hospitals has announced the launch of clinical genomic tests from the Strand Center for Genomics and Personalised Medicine across its hospital network which will help doctors diagnose disease precisely and identify optimal treatment.
These tests in oncology, cardiovascular, heritable eye diseases and rare genetic disorders shall be integrated into clinical practice by Apollo's subsidiary, Sapien Biosciences in partnership with Strand Life Sciences, it said in a statement yesterday.
"These tests will help doctors diagnose disease more precisely, identify the optimal treatment and monitor disease and treatment course for better outcomes," it said.
Genomic testing involves analysis of patient genomes genes and sequences of DNA/RNA. The analysis helps create better prognostic tools for improved disease screening and prevention strategies. The patient benefits from optimised clinical care, personalisation of treatment and monitoring of outcomes, it was noted.
25th Jul 2014, 01:45 PM #1299
Re: Health Bulletin
Secret of early puberty discovered
British scientists may have finally found an answer to the phenomenon of early puberty affecting modern day girls.
The University of Cambridge, in the largest study of its kind - involving more than 180,000 women and scientists from 166 institutions worldwide have found that the age at which girls reach sexual maturity is influenced by "imprinted" genes - a small sub-set of genes whose activity differs depending on which parent passes on that gene.
In a family, one parent may more profoundly affect puberty timing in their daughters than the other parent.
The researchers identified 123 genetic variations that were associated with the timing of when girls experienced their first menstrual cycle by analysing the DNA of 182,416 women of European descent from 57 studies.
Six of these variants were found to be clustered within imprinted regions of the genome.
Lead author Dr John Perry at the Medical Research Council (MRC) Epidemiology Unit, University of Cambridge says "Normally, our inherited physical characteristics reflect a roughly average combination of our parents' genomes, but imprinted genes place unequal weight on the influence of either the mother's or the father's genes. Our findings imply that in a family, one parent may more profoundly affect puberty timing in their daughters than the other parent".
Now, girls in India are reaching puberty, two years earlier. The age of attaining sexual maturity among a girl, when she changes physically, hormonally and sexually has dipped, especially in urban India, to 10 years from 12-13 earlier. Scientists now say that the age of 18 years clearly no longer signifies adulthood. The the earlier onset of puberty has increased the window of risk associated with adolescence.
The activity of imprinted genes differs depending on which parent the gene is inherited from - some genes are only active when inherited from the mother, others are only active when inherited from the father. Both types of imprinted genes were identified as determining puberty timing in girls, indicating a possible biological conflict between the parents over their child's rate of development. Further evidence for the parental imbalance in inheritance patterns was obtained by analyzing the association between these imprinted genes and timing of puberty in a study of over 35,000 women in Iceland, for whom detailed information on their family trees were available. This is the first time that it has been shown that imprinted genes can control rate of development after birth.
Dr Perry says "We knew that some imprinted genes control antenatal growth and development - but there is increasing interest in the possibility that imprinted genes may also control childhood maturation and later life outcomes, including disease risks."
Senior author and pediatrician Dr Ken Ong at the MRC Epidemiology Unit says "There is a remarkably wide diversity in puberty timing - some girls start at age 8 and others at 13. While lifestyle factors such as nutrition and physical activity do play a role, our findings reveal a wide and complex network of genetic factors. We are studying these factors to understand how early puberty in girls is linked to higher risks of developing diabetes, heart disease and breast cancer in later life - and to hopefully one day break this link."
Dr Anna Murray, a co-author from the University of Exeter Medical School, adds "We found that there are hundreds of genes involved in puberty timing, including 29 involved in the production and functioning of hormones, which has increased our knowledge of the biological processes that are involved, in both girls and boys."
26th Jul 2014, 08:59 AM #1300
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Re: Health BulletinNow, girls in India are reaching puberty, two years earlier. The age of attaining sexual maturity among a girl, when she changes physically, hormonally and sexually has dipped, especially in urban India, to 10 years from 12-13 earlier. Scientists now say that the age of 18 years clearly no longer signifies adulthood. The the earlier onset of puberty has increased the window of risk associated with adolescence.