Posted: 24 November 2011
PARIS: The word's first artificial windpipe transplant has been such a success that a second operation has been carried out and a third is being planned, The Lancet reported on Thursday.
Andemariam Teklesenbet Beyene, a 36-year-old Eritrean, is doing well after undergoing the ground-breaking operation in Stockholm in June, it said.
Beyene, a post-graduate geology student currently living in Reykjavik, Iceland, had his trachea removed because of cancer.
It was replaced in a 12-hour operation on June 9 with a synthetic "scaffold" covered with his own stem cells, or precursor cells of windpipe tissue.
"The patient has been doing great for the last four months and has been able to live a normal life," the British journal quoted Tomas Gudbjartsson, a professor at Landspitali University Hospital and University of Iceland in Reykjavik, as saying.
"For the last two months he has been able to focus on his studies and the plan is that he will defend his thesis at the end of this year."
The operation, led by Professor Paolo Macchiarini of Stockholm's Karolinska University Hospital, entailed using 3-D imaging to scan Beyene and then building a glass model of the afflicted section of his windpipe.
The glass was used to shape the artificial scaffold, which was then seeded with stem cells.
Macchiarini has just carried out his second transplant, on a 30-year-old man from Maryland, United States, who also had cancer of the trachea. The scaffold was made from nanofibres and thus "represents a further advance," the Journal quoted Macchiarini as saying.
His team is now hoping to treat a 13-month-old South Korean infant with the same technique.
"We will continue to improve the regenerative medicine approaches for transplanting the windpipe and extend it to the lungs, heart, and oesophagus," said Macchiarini.
It marks a step forward in regenerative medicine, as the organ is tailor-made to the patient, he said.
In addition, artificial organs do not require the long waiting time that usually happens in human donation.
As the stem cells come from the patient himself, this reduces risk of attack by the immune system, which is the case for donated organs whose rejection has to be combatted by taking powerful immunosuppressive drugs.
-AFP/pn
Taken from ChannelNewsAsia.com; source article is below:
First artificial windpipe graft a success
A long-term study, now this is something!
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Posted: 23 November 2011
PARIS: Statins safely reduce the risk of cardiovascular illness even years after treatment is stopped, according to a probe into the popular cholesterol-busters published on Wednesday.
Statins work by blocking a liver enzyme that makes fatty molecules which line arterial walls and boost the danger of heart disease and strokes.
With worldwide annual sales of more than 20 billion dollars, the drugs have been dubbed "the aspirin of the 21st century" because of their benefit and wide use.
But lingering questions persist about their long-term safety for the heart, liver and cancer risk.
Researchers at the Heart Protection Study Collaborative Group in Oxford looked at 20,536 patients at risk of cardiovascular disease who were randomly allocated 40mg daily of simvastatins or a dummy look-alike over more than five years.
During this period, those who took the statins saw a reduction in "bad" LDL cholesterol and a 23-per cent reduction in episodes of vascular ill-health compared to the placebo group.
The monitoring of the volunteers continued for a further six years after the trial ended.
The benefits persisted throughout this monitoring period among those volunteers who stopped taking the statins, the investigators found.
In addition, there was no emergence of any health hazard among those who had taken, or were continuing to take, the drugs.
A large number of cancers (nearly 3,500) developed during this follow-up period, but there was no difference in cancer incidence between the statin and placebo groups.
"The persistence of benefit we observed among participants originally allocated simvastatin during the subsequent six-year post-trial period is remarkable," said one of the investigators, Richard Bulbulia.
"In addition, the reliable evidence of safety, with no excess risk of cancer or other major illnesses during over 11 years follow-up, is very reassuring for doctors who prescribe statins and the increasingly large numbers of patients who take them long-term to reduce their risk of vascular disease."
A previous investigation in November 2010 found that long-term use of statins was less risky than thought for people with non-alcoholic fatty liver disease (NAFLD), a common liver ailment.
- AFP/ck
Taken from ChannelNewsAsia.com; source article is below:
Long-term study proves benefit of statins in heart disease
Another breakthrough, a medical advancement...
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Posted: 16 November 2011
LONDON: British doctors on Tuesday said they had cured a baby boy of a life-threatening liver disease using a pioneering treatment in which cells are injected into the abdomen.
The team from London's King's College Hospital treated eight-month old Iyaad Syed by injecting him with a group of cells, which acted as a temporary
liver while his real organ recovered from damage caused by a virus, BBC reported.
"This is the first time this treatment has been used to treat a child with acute liver failure," said professor Anil Dhawan, a liver specialist at the hospital.
"It's only a few months back when I first saw this child who was so sick requiring support on dialysis and a breathing machine.
"We think we have given him another chance of life and seeing him now six months down the road with nearly normal liver function is remarkable."
Syed would normally have been put on the transplant waiting list when his liver began to fail, but the hope now is that more cases will be cured using the new technique rather than relying on a scarce supply of donor organs.
Doctors injected liver cells which then processed toxins and produced proteins, fulfilling the role of a temporary liver while his own began to recover two weeks later.
The cells were treated with a chemical to prevent them from being destroyed by the youngster's immune system.
Iyaad's father, Jahangeer, called his son "a miracle boy", adding "it is brilliant and we are very proud of him."
The treatment's development now depends on an extensive clinical trial.
Andrew Langford, Chief Executive of the British Liver Trust, told the BBC: "The principle of this new technique is certainly ground-breaking and we would welcome the results of further clinical trials to see if it could become a standard treatment for both adults and children.
"Sadly, we have reached a breaking point with our transplant list in the UK, where approximately 100 people die waiting for a donor liver to become available each year."
-AFP/vl
Taken from ChannelNewsAsia.com; source article is below:
Pioneering liver treatment cures British baby
Posted: 15 November 2011
PARIS: Stem cells from heart-attack patients helped improve blood-pumping ability and restore vitality in cardiac muscle, according to a small trial published on Monday.
It is the first time patients have been given an infusion of their own
cardiac stem cells in the aim of solving the impact of heart failure rather than simply treating the symptoms of it.
The findings are so promising that the study's chief investigator said a potential "revolution" was in the offing if larger trials succeeded.
Stem cells are infant cells that develop into the specialised tissues of the body.
They have sparked great excitement as they offer hopes of rebuilding organs damaged by disease or accident.
The new study, published online in The Lancet, tested cardiac stem cells on 16 patients who had been left gravely ill as a result of an acute myocardial infarction.
The index used for cardiac health is called the left ventricular ejection fraction (LVFV), which calculates the capacity of the left ventricle to expel blood in the space of a heartbeat.
For a person in normal health, the LVFV is 50 percent or higher.
Among the study patients, though, this had fallen to 40 percent or lower. At such a threshold, shortness of breath and fatigue are chronic and often disabling.
The stem cells were isolated from a coronary artery that had been removed when the patients underwent a coronary bypass.
Within four months of treatment, the LVFV rose by 8.5 percent and after a year by 12 percent - four times what the researchers had expected.
Scans of the patients' hearts also showed a reduction in the area of tissue that had been scarred by the infarction, a discovery that challenges conventional belief that once scarring occurs, heart tissue is permanently dead.
The volunteers also reported a substantial improvement in quality of life, and there were no significant side effects.
Seven patients with similar heart problems were enrolled as "controls", to serve as a comparison. There was no change in their LVFV, in scar tissue or in their quality of life.
"The results are striking," said lead investigator Roberto Bolli of the University of Louisville, Kentucky.
"While we do not know why the improvement occurs, we have no doubt now that 1/8LVFV 3/8 increased and scarring decreased.
"If these results hold up in future studies, I believe this could be the biggest revolution in cardiovascular medicine in my lifetime."
The team is seeking funding to launch a larger, or Phase II, trial - the second in the normal three-phase process of assessing a new treatment for safet and effectiveness.
Previous stem-cell work on heart damage has used cells harvested from bone marrow.
The interest in cardiac stem cells is that they are self-renewing, produce daughter cells and differentiate into all types of cells in the heart.
The results were presented concurrently at a meeting of the American Heart Association in Orlando, Florida.
-AFP/pn
Taken from ChannelNewsAsia.com; source article is below:
Broken heart fix with stem cells
Posted: 09 November 2011
WASHINGTON: A post-mortem analysis of half a dozen autistic boys showed that their brains were heavier and contained many more neurons than counterparts without the disorder, US researchers said Tuesday.
The study, while small, suggests that brain overgrowth may be occurring in the womb, according to the findings published in the November 9 issue of the Journal of the American Medical Association.
Researchers examined the brains of seven autistic boys, age two to 16, most of whom had died by drowning. The 16-year-old's cause of death was undetermined and one eight-year-old died of muscle cancer.
When they compared them to a control group of six boys without autism who died in accidents, they found that the brains of autistic boys had 67 percent more neurons in the prefrontal cortex and were nearly 18 percent heavier than normal brain weight for age.
"Because cortical neurons are not generated in postnatal life, this pathological increase in neuron numbers in autistic children indicates prenatal causes," the study said.
The researchers suggested that "faulty prenatal cell birth or maintenance may be involved in the development of autism."
The prefrontal cortex is where language and communication is based, as well as behaviors such as mood, attention, and social ability. Typically, autistic children have difficulty in these areas.
However, more research is needed to confirm the link, and to determine if and how brain differences may be tied to the severity of an autistic person's symptoms.
"Factors that normally organize the brain appear to be disrupted," said an accompanying editorial by Janet Lainhart of the University of Utah and Nicholas Lange of the Harvard University Schools of Medicine and Public Health.
Previous studies have suggested that clinical signs of autism tend to coincide with a period of abnormal brain and head growth that usually becomes apparent at nine to 18 months of age, according to the article.
Autism includes a wide spectrum of developmental differences and may range from mild social awkwardness to complete inability to communicate, repetitive movements, sensitivity to certain lights and sounds, and behavioral problems.
As many as one in 110 children is diagnosed with autism. The disorder is three to four times more common in boys than in girls, according to the advocacy group Autism Speaks which helped fund the study.
Other funding came from Cure Autism Now, The Emch Foundation, the Simons Foundation, the Thursday Club Juniors, and the University of California San Diego - National Institutes of Health Autism Center of Excellence.
-AFP/pn
Taken from ChannelNewsAsia.com; source article is below:
Autistic brains are heavier, with more neurons: study
Posted: 20 September 2011
WASHINGTON: Sharks are primitive creatures but their bodies produce a sophisticated substance that shows promise in fighting a range of human viruses from hepatitis to yellow fever, researchers said on Monday.
The compound, called squalamine, was discovered in 1993 but the study in the Proceedings of the National Academies of Sciences is the first to explore its potential use against human viruses.
Researchers tested squalamine - manufactured from dogfish sharks' livers - in lab dishes and in animal subjects and found it could inhibit or control viral infections, and in some cases appeared to cure animals of their ills.
The project began when lead investigator, Michael Zasloff, professor of surgery and paediatrics at Georgetown University Medical Center, sent samples of squalamine to a series of labs around the United States for testing.
Squalamine has been synthesised in a lab since 1995 and is no longer extracted directly from shark tissue.
Tissue cultures showed it could "inhibit the infection of human blood vessel cells by the dengue virus and human liver cells infected with hepatitis B and D," said the study.
Research on animals showed the compound controlled yellow fever, Eastern equine encephalitis virus, and murine cytomegalovirus, a type of herpes virus that afflicts rodents.
"It is clearly a promising drug, and is unlike, in its mechanism of action and chemical structure, any other substance currently being investigated to treat viral infections," said Zasloff.
"We have not yet optimised squalamine dosing in any of the animal models we have studied and as yet we do not know the maximum protective or therapeutic benefit that can be achieved in these systems," he added.
"But we are sufficiently convinced of the promise of squalamine as an antiviral agent that we intend to take this compound into humans."
Squalamine is safe for humans and has been considered a potential tool against cancer and eye diseases, and some clinical trials for those targets are ongoing.
"In several of the early trials squalamine has shown significant and promising activity... in both certain forms of cancer and in diabetic retinopathy," Zasloff told AFP in an email.
Zasloff discovered squalamine in 1993 and is also known for his research on the natural antibiotic properties of frog skin.
- AFP/de
Taken from ChannelNewsAsia.com; source article is below:
Secret to shark health could fight human viruses
Posted: 25 August 2011
PARIS - Scientists say they've found on a new way of controlling dengue fever by weakening populations of mosquitoes carrying the virus which causes the deadly disease.
"The results show we can completely transform local (mosquito) populations in a few months," said Michael Turelli, a biologist at the University of California at Davis. "It's natural selection on steroids."
Dengue which affects between 50 and 100 million people in the tropics and subtropics each year, is caused by four strains of virus that are spread by the mosquito Aedes aegypti.
There is no vaccine, which is why scientists are focussing so intensely on mosquito control.
In 2009, Turelli and others hit on the idea of inserting a naturally-occurring bacterial parasite called Wolbachia to shorten the mosquito's lifespan so that the virus would not have enough time to develop.
After initial setbacks, the team of scientists found a non-virulent strain of Wolbachia in the fruitfly Drosphila.
Introduced into the mosquito, the germ prevented the insect from becoming infected by the dengue virus.
At the same time, the Wolbachia which is a symbiotic bacterium, it was also harmless to the mosquito as it exists by living in harmony with its host.
As it lives inside cells and is maternally inherited, this raises the possibility that after a few generations, the introduced dengue-free mosquitoes eventually outnumber dengue-carrying counterparts.
After long consultations with the government and regulators, the scientists released Wolbachia-infected mosquitoes in two locations in Queensland, Australia, this year.
Early results suggest that the introduced mosquitoes have thrived, and "herald the beginning of a new era in the control of mosquito-borne diseases," said Jason Rasgon, a specialist at the Johns Hopkins Malaria Research Institute, Maryland, in a commentary also carried by Nature.
"The advantage of population-replacement approaches is that, once established, they are self-propagating. And because the mosquito population is simply changed rather than eliminated, effects on the ecosystem should be minimal."
The paper appears in Nature, the weekly British science journal.
- AFP/sf
Taken from ChannelNewsAsia.com; source article is below:
Dengue fever under attack through smart mosquito control
Posted: 25 August 2011
SINGAPORE: Scientists from Nanyang Technological University (NTU) have for the first time re-engineered a common bacterium to seek out and kill other dangerous bacteria, to target a superbug which is naturally resistant to a wide range of antibiotics.
The breakthrough could change the way medical treatment is currently done in hospitals, as it targets only harmful bacteria, unlike the existing broad-spectrum antibiotics which kill both good and bad bacteria.
In a media release on Wednesday, NTU said its scientists were able to modify a harmless strain of Escherichia coli - also known as E. coli - found naturally in the human digestive system, to target a superbug which causes infections such as upper respiratory tract infection, gastrointestinal tract infection and urinary tract infection.
The biochemically engineered E. coli, upon detection of the other bacterium, will generate "killing molecules", and then self-destruct to release these molecules to kill the superbug, while remaining harmless to the human body.
The results have generated interest in the biomedical industry, which is looking for ways to combat infection - one of the world's leading causes of death, said NTU.
The researchers, Assistant Professor Matthew Chang and Assistant Professor Poh Chueh Loo from NTU's School of Chemical and Biomedical Engineering, said the idea for the project came about after they observed that bacteria secrete toxins to kill other bacteria in their bid for survival under adverse competition.
They plan to refine the efficiency of the killing molecules and to find other possible targets, and expect to soon move into animal trials. - TODAY
Taken from ChannelNewsAsia.com; source article is below:
NTU scientists achieve bacterium breakthrough
Are you one of them? Take heed...
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Posted: 01 August 2011
LONDON - Nearly 100 children aged between five and seven in Britain have been treated for anorexia or bulimia in the past three years, according to figures released on Monday.
The statistics show that 197 children aged between five and nine were treated in hospital in England for eating disorders, fuelling campaigners' fears that young children are being influenced by photographs in celebrity magazines.
The figures from 35 hospitals showed 98 children were aged between five and seven at the time of treatment and 99 aged eight or nine. Almost 400 were between the ages of 10 and 12, with more than 1,500 between 13 and 15 years old.
The statistics, released under the Freedom of Information Act, are believed to underestimate the true figures because some state-run hospitals refuse to release any data.
Other hospitals would only release figures for children admitted after they had become dangerously thin, excluding those undergoing psychiatric therapy as outpatients.
The findings come after experts called earlier this year for urgent action to improve the detection of eating disorders in children.
About three in every 100,000 children under 13 in Britain and Ireland have some sort of eating disorder, according to a study conducted by experts from University College London's Institute for Child Health.
Susan Ringwood, chief executive of the eating disorders charity B-eat, said the latest figures reflected "alarming" trends in society, with young children "internalising" messages from magazines which idealise the thinnest figures.
"A number of factors combine to trigger eating disorders. Biology and genetics play a large part in their development, but so do cultural pressures, and body image seems to be influencing younger children much more over the past decade," she said.
Children were receiving "pernicious" messages, Ringwood told the Sunday Telegraph.
"The ideal figure promoted for women is that of a girl, not an adult woman. That can leave girls fearful of puberty, and almost trying to stave it off," she said.
The Department of Health said it was spending US$660 million over the next four years on psychological treatment for eating disorders, including a specific programme for children and young people.
"Early intervention is essential for those with eating disorders," a spokeswoman said.
- AFP/ir
Taken from ChannelNewsAsia.com; source article is below:
Anorexic at five
By Leong Wai Kit, channelnewsasia.com | Posted: 24 July 2011
SINGAPORE: When Wong Jun Da was diagnosed with cancer at nine years old, the boy knew there was nothing he could do about it – which was why he decided his world must not come crashing down.
"At that age, I do know about cancer and what it means to have cancer," says the acute lymphoblastic leukemia (ALL) survivor, who is now 16.
"I thought about it for a while, and how it would affect me in future. But after about two minutes, I tried to snap out of it and accept that reality," Jun Da says, recalling his reaction in June 2004 at KK Women's and Children's Hospital.
"Even if I were to cry over it, there is nothing I can do to change that fact," he adds.
Fortunately for Jun Da, doctors did change that fact.
Childhood cancers in S'pore
Every year, about 100 new cases of cancer are reported in Singapore, with ALL being the most common one.
Treatment for ALL include chemotherapy, radiation and in some cases, bone marrow transplants.
The survival rate for children with ALL is at between 70 and 90 per cent, which is "very good", says the Children's Cancer Foundation (CCF).
A dose of determination
Jun Da began chemotherapy in June 2004 but suffered a relapse in September 2005.
He was then put through more intensive treatment, including full-body radiation in 2005 followed by a cord blood transplant in 2006.
To focus on his treatment, Jun Da stopped attending school for two years when he was in primary five.
His mom, Mdm Koh Bee Geok, says: "We didn't hire tutors because Jun Da said he could self-study so we let him do that for two years.
"A few days before his PSLE (Primary School Leaving Examination), he was warded for bronchitis and had to sit for the exam in hospital."
But that did not stop Jun Da, who aspires to be an artist, from doing well enough to get into the express stream in Bedok South Secondary School.
Something to smile about
By the time Jun Da was cleared of his cancer in May 2009 - at age 14 – he had already undergone about six surgeries.
Although his treatment was not a bed of roses, Jun Da often tries to find something to smile about.
"I was able to look on the brighter side despite my condition because I think I had some maturity to begin with.
"And I think having cancer didn't kill that optimism but instead, helped me appreciate the things around me.
"For instance, though cancer stopped me from being a child for two years, I gained in other ways, including forming close friendships with nurses and social workers (from CCF)."
These days, Jun Da the survivor has been actively giving back to the community.
Besides doing volunteer work with Make a Wish, an organisation which helps grant the wishes of children with life-threatening medical conditions, Jun Da also makes time to share his experience with other children with cancer.
And on Sunday, Jun Da will help out at the CCF's Hair for Hope event at VivoCity, to raise funds for children with cancer.
The CCF, which has served about 1,950 families since 1996, needs about S$3.5 million each year. Donations can be made to the CCF via its website at http://www.ccf.org.sg/sponsors_donors/donate.html
-CNA/wk/ac
Taken from ChannelnewsAsia.com; source article is below:
The boy who beat cancer
Will this encourage cooking at home?
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Posted: 21 July 2011
WASHINGTON - US First Lady Michelle Obama on Wednesday teamed up with major food retailers to launch an attack on "food deserts" as a key part of the US battle to bring down childhood obesity.
"We can give people all the information and advice in the world about healthy eating and exercise, but if parents can't buy the food they need to prepare those meals because their only options for groceries are the gas station or the local minimart, then all that is just talk," Obama said.
Many US inner cities are "food deserts," or areas where shops selling healthful foods are rare or expensive, and residents, many of them poor, live on cheap processed meals and sugary drinks, which pile on the pounds while providing scant nutritional benefits.
On Wednesday, major food retailers including Wal-Mart, Supervalu supermarkets and Walgreen's, pledged to open more than 1,500 shops over the next five years to sell fresh, nutritious foods in communities throughout the country that are currently underserved.
The fight against "food deserts" is one of the linchpins in Obama's "Let's Move" campaign, launched last year to try to bring down the staggering rate of childhood obesity, which affects one in five children in the United States.
When overweight children are included in the tally, one in three American kids is found to have a weight problem.
"There's a reason why we set a goal that every family in every community in America would have access to fresh, healthy, affordable food," Obama said.
"'Let's Move' is about giving parents real choices about the food their kids are eating.
"If a parent wants to pack a piece of fruit in a child's lunch, if a parent wants to add some lettuce for a salad at dinner, they shouldn't have to take three city buses or pay some expensive taxi to go to another community to make that possible," she added.
"They should have fresh food retailers right in their communities -- places that sell healthy food at reasonable prices so that they can feed their families in the way that they see fit, because when they have those choices, that can have a real, measurable impact on a family's health."
Melody Barnes, director of the White House Domestic Policy Council, said making healthy food affordable and accessible "is critical if we are to address the issue of childhood obesity.
"Most Americans are startled to know that one in three American children is overweight or obese," she said.
Nearly half of kids with weight problems live in poverty and in neighborhoods with no shops that sell fresh foods, she added.
According to the White House, some 23.5 million Americans, including 6.5 million children, who currently live in "food deserts" would benefit from having a shop selling fresh food in their neighborhood.
The new shops would not only be a step in the right direction in the fight against obesity but would also help to raise people out of poverty by creating tens of thousands of jobs in their communities, Barnes said.
When she launched "Let's Move" last year, Michelle Obama called childhood obesity an "epidemic" and "one of the most serious threats" to US children's futures.
Ending food deserts is just one of the pieces in the First Lady's broader initiative to "solve the problem of childhood obesity in a generation so that children born today will reach adulthood at a healthy weight."
The other pillars of "Let's Move" include making American kids more active, improving the quality of school meals, offering kids more safe opportunities to be physically active, and educating them on good nutrition and healthy eating.
-AFP/rt
Taken from ChannelNewsAsia.com; source article is below:
Michelle Obama launches attack on US food deserts
We've used these in the provinces since time immemorial? Only now that the city dwellers are catching up?
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Posted: 21 June 2011
WASHINGTON: A team of Swiss and French scientists published a study on Monday that suggests the rocking motion of a hammock improves sleep quality and helps people get to sleep faster.
The study included 12 male volunteers who were not habitual nappers but who agreed to try an afternoon snooze on both a stationary bed and a rocking bed while machines scanned their brains, eye and muscle movements.
Women were excluded from the study because the menstrual cycle can have an effect on electroencephalogram (EEG) monitoring, the researchers said.
Two of the 12 men had to be left out of the final analysis because one had a malfunctioning EEG and one experienced too much anxiety to fall asleep on the day he was assigned to the stationary bed.
But the remaining 10 subjects fell asleep faster in the rocking bed than they did in the still one and the quality of their 45-minute nap was deeper, said the findings published in the journal Current Biology.
"We observed a faster transition to sleep in each and every subject in the swinging condition, a result that supports the intuitive notion of facilitation of sleep associated with this procedure," said Michel Muhlethaler of the University of Geneva.
"Surprisingly, we also observed a dramatic boosting of certain types of sleep-related (brain wave) oscillations."
A midway sleep stage known as N2, which includes no rapid eye movements and usually makes up about half of a sound period of sleep, was observed to be longer in the hammock-type bed.
"The rocking bed also had a lasting effect on brain activity, increasing slow oscillations and bursts of activity known as sleep spindles. Those effects are consistent with a more synchronised neural activity characteristic of deeper sleep," said the study.
Researchers hope to examine whether the hammock effect would be similar in longer stretches of sleep, and would like to find out if it can be harnessed to help people who suffer from insomnia.
- AFP/de
Taken from ChannelNewsAsia.com; source article is below:
Scientists study 'hammock' effect on sleep
Maybe this explains why there are more apes and chimps around than expected, especially in the business world...?
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Posted: 14 June 2011
PARIS - Humans may be evolving a third as slowly as commonly thought, according to an investigation into genetic changes in two generations of families.
The genetic code comprises six billion nucleotides, or building blocks of DNA, half of which come from each parent.
Until now, the conventional theory among scientists was that parents each contribute between 100 and 200 changes in these nucleotides.
But the new study says that far fewer changes occur. Each parent hands on 30 on average.
"In principle, evolution is happening a third as slowly as previous thought," said Philip Awadalla of the University of Montreal, who led the study by the CARTaGENE group.
The discovery came from a painstaking look at the genomes of two families, each comprising a mother, a father and their child.
The study breaks new ground although its sample size is very small.
If confirmed on a wider scale, it will have a bearing on the chronology of evolution. It would change the way we calculate the number of generations that separate Homo sapiens from a primate forebear who is also the ancestor of the apes.
The study also challenged thinking about whether DNA changes are more likely to be handed on by the father or by the mother.
The mainstream notion is that DNA changes -- known in scientific terms as mutations -- are likelier to be transmitted by the man.
This is because mutations occur during cell division and DNA replication, and thus are much likelier to happen in sperm, for which many millions are made, than in eggs.
In one of the families, 92 percent of the changes were derived from the father.
But in the other family, only 36 percent of the mutations came from the paternal side.
"The mutation rate is extremely variable from individual to individual or...some people have mechanisms that reduce the likelihood of mutations," concluded Awadalla.
This variability could prompt a rethink on predicting the risk of inherited disease, caused by flawed genes bequeathed by one or both parents.
Some individuals might be at risk of misdiagnosis of a genetic disease if they have a higher natural mutation rate than the benchmark rate, he suggested.
-AFP/rt
Taken from ChannelNewsAsia.com; source article is below:
Human evolution slower than thought, say scientists
