Youth with superior IQ are distinguished by how fast the thinking part of their brains thickens and thins as they grow up, researchers at the US National Institutes of Health's (NIH) National Institute of Mental Health (NIMH) have discovered. Magnetic resonance imaging (MRI) scans showed that their brain's outer mantle, or cortex, thickens more rapidly during childhood, reaching its peak later than in their peers – perhaps reflecting a longer developmental window for high-level thinking circuitry.
It also thins faster during the late teens, likely due to the withering of unused neural connections as the brain streamlines its operations. Drs Philip Shaw, Judith Rapoport, Jay Giedd and colleagues at NIMH and McGill University report on their findings in the 30 March 2006 issue of Nature.
“Studies of brains have taught us that people with higher IQs do not have larger brains. Thanks to brain imaging technology, we can now see that the difference may be in the way the brain develops,” said NIH director Elias A Zerhouni, MD.
While most previous MRI studies of brain development compared data from different children at different ages, the NIMH study sought to control for individual variation in brain structure by following the same 307 children and teens, ages 5-19, as they grew up.
The researchers found that the relationship between cortex thickness and IQ varied with age, particularly in the prefrontal cortex, seat of abstract reasoning, planning, and other “executive” functions.
The smartest 7- year-olds tended to start out with a relatively thinner cortex that thickened rapidly, peaking by age 11 or 12 before thinning. In their peers with average IQ, an initially thicker cortex peaked by age 8, with gradual thinning thereafter.
“Brainy children are not cleverer solely by virtue of having more or less gray matter at any one age,” explained Rapoport. “Rather, IQ is related to the dynamics of cortex maturation.” The observed differences are consistent with findings from functional magnetic resonance imaging, showing that levels of activation in prefrontal areas correlates with IQ, note the researchers.
They suggest that the prolonged thickening of prefrontal cortex in children with superior IQs might reflect an “extended critical period for development of high-level cognitive circuits.” Although it's not known for certain what underlies the thinning phase, evidence suggests it likely reflects “use-it-or-loseit” pruning of brain cells, neurons, and their connections as the brain matures and becomes more efficient during the teen years.
Artificial heart 1
On 22 March, a 48-year-old male patient suffering NYHA Class IV Heart Failure became the first recipient of HeartWare’s HVAD mechanical circulatory assist device.
The implant was conducted at the Vienna General Hospital and the surgical team was led by Dr Georg Wieselthaler, clinical director of Mechanical Circulatory Support at the University of Vienna.
The successful implant marks the start of HeartWare’s CE mark clinical study. The trial protocol calls for the implantation of the device in 20 patients suffering advanced heart failure.
The implants are to be conducted at the Vienna General Hospital (Austria), the Royal Perth Hospital Australia), the Hannover Medical Centre (Germany) and Harefield Hospital (UK).
HeartWare expects to complete patient enrolment in the trial by the end of 2006. Commenting on the first implant, Dr Wieselthaler said: “Our first clinical experience of the HVAD was extremely positive.
The procedure was completed quickly and without incident, and our patient’s early post-operative recovery has been excellent.” The HVAD is the smallest 3rd generation circulatory assist device available. It is the only full-output pump implantable in the pericardial space and the only centrifugal pump implantable above the diaphragm.
The pump's impeller design, together with its integrated inflow cannula, help to ensure optimal blood flow characteristics which should, over time, allow reduction of the anticoagulant levels typically required for LVAD recipients. The HVAD's unique design should allow long term device durability - providing the genuine prospect of “lifelong” therapy.
Artificial heart 2
A cardiac surgery team at Virginia Commonwealth University’s Pauley Heart Center, Virginia, United States, has performed the first artificial heart implant on the US East Coast.
The CardioWest temporary Total Artificial Heart, or TAH-t, is the only total artificial heart approved by the FDA, Health Canada and Communité Europeenne. The patient, a man in his late 50’s from Virginia, was in stable condition following the seven-hour implant surgery.
He had been critically ill suffering from endstage heart failure. The TAHt replaces his damaged heart while he waits for a donor heart to become available for transplant. The TAH-t is a modern version of the Jarvik-7 Artificial Heart of the 1980s.
Survival rates have increased dramatically because of technological advances that provide improved blood flow, along with major therapeutic advancements to reduce the occurrence of strokes and life threatening bleeding.
The TAH-t serves as a bridge to heart transplant for critically ill patients with end-stage biventricular failure. The artificial heart pumps up to 9.5 litres of blood per minute through both ventricles – more than any other device – helping to rejuvenate vital organs that have atrophied due to a failing heart. In 2004, the American Heart Association named the TAH-t the No. 1 advance in cardiovascular medicine.
An August 2004 paper in the New England Journal of Medicine found in a pivotal clinical trial that the one-year survival rate following human heart transplant for patients receiving the TAH-t was 70%, versus 31% for control patients.
Sleep & diabetes
Men who sleep too much or too little are at an increased risk of developing Type 2 diabetes, according to a study by the New England Research Institutes in collaboration with Yale School of Medicine researchers.
The data published in the March issue of Diabetes Care (Diabetes Care 29: 657-661 [March 2006]) were obtained from 1,709 men, 40 to 70 years old.
The men were enrolled in the Massachusetts Male Aging Study and were followed for 15 years with home visits, a health questionnaire and blood samples. Six to eight hours of sleep was found to be most healthy.
In contrast, men who reported they slept between five and six hours per night were twice as likely to develop diabetes and men who slept more than eight hours per night were three times as likely to develop diabetes, according to the lead author, H Klar Yaggi, MD, professor in Yale's Department of Internal Medicine, pulmonary section. Previous data from the Nurses Health Study have shown similar results in women.
Scientists at Karolinska Institutet in Sweden have helped to identify a molecule that can be used as a vaccination agent against growing cancer tumours.
Although the results are so far based on animal experiments, they point to new methods of treating metastases. The results are presented in the online edition of the prestigious scientific journal Nature Medicine, and represent the collaborative efforts of researchers at KI and Leiden University Medical Centre in Holland.
The study analysed an immunological cell, a T cell, which recognises other cells with defects common to metastasing ones. These defects (which are found in MHC class 1 molecules) allow the tumour cell to evade the “conventional” T cell-mediated immune defence. The researchers have identified a short peptide molecule that the T cell in the study recognises.
Using this peptide, the researchers can vaccinate and protect against the spread of tumours from different tissues, including melanoma, colon cancer, lymphoma, and fibrosarcoma.
Nano delivery vehicles
Researchers have developed “custom” nanoparticles that show promise of providing a more targeted and effective delivery of anticancer drugs than conventional medications or any of the earlier attempts to fight cancer with nanoparticles.
Designed at the molecular level to attack specific types of cancer without affecting healthy cells, the nanoparticles also have the potential to reduce side effects associated with chemotherapy, the researchers say.
Their study was described 26 March at the 231st national meeting of the American Chemical Society, the world’s largest scientific society. The particles, considered the next generation of cancer therapeutics, are the most uniform, shapespecific drug delivery particles developed to date, according to researchers at the University of North Carolina (UNC) in Chapel Hill.
Other potential benefits of the tiny uniform particles include enhanced imaging of cancer cells for improved diagnosis and use as delivery vehicles for gene therapy agents, they say.
To date, the UNC researchers have produced a variety of custom nanoparticles from biocompatible organic materials using techniques they adapted from processes used by the electronics industry to make transistors. In cell studies, they have shown that the uniform nanoparticles can attach to specific cell targets, release important chemotherapy drugs inside cells, and hold MRI contrast agents.
Animal studies began recently and human studies are anticipated, the researchers say. “I think this will transform the way one detects and treats disease,” says study leader Joseph DeSimone, PhD, a chemistry professor at UNC and director of the school’s Institute for Advanced Materials, Nanoscience and Technology.
“Stop TB” guidelines
Led by the American Thoracic Society (ATS) and the World Health Organisation (WHO), a consortium of international health agencies recently published on the World Wide Web the first International Standards for Tuberculosis Care (ISTC). www.who.int/tb
“The purpose of the ISTC,” said Philip C Hopewell, MD, who co-chaired the committee that produced the standards “is to establish a widely accepted level of care that all practitioners, public and private, should achieve in managing patients who have, or are suspected of having, tuberculosis.”
The ISTC is part of the WHO's new Stop TB Strategy and the Global Plan to Stop TB 2006-2015 developed by the Stop TB Partnership. The Stop TB Partnership consists of more than 300 organisations worldwide that are concerned with tuberculosis care and control.
Third heart sound
Physicians with more experience are better able to detect a third heart sound that is an indicator of heart disease, according to a study on stethoscope accuracy in cardiac patients at University of California San Francisco Medical Center, United States.
Greater experience in auscultation – listening to body sounds with a stethoscope – provides better outcomes in detecting pathologic heart disorders, underscoring the importance of skilled instruction in the use of a stethoscope, the researchers said. Their findings appear in the 27 March 2006, edition of The Archives of Internal Medicine.
The third heart sound, known as S3, is a lowpitched vibration that occurs in early diastole, a phase in the heart's pumping cycle characterised by the rhythmic relaxation and dilatation of the heart chambers. While present in children and adolescents, the sound normally diminishes in adulthood.
“The presence of an S3 is associated with adverse cardiovascular outcomes in adult patients,” said senior author Andrew Michaels, MD, assistant professor of cardiology at UCSF and codirector of the Cardiac Catheterization Laboratory at UCSF Medical Center. “The pathologic S3 indicates decreased compliance of the ventricles of the heart and may be the earliest sign of heart failure.”
New chemo device
A new method of delivering chemotherapy to cancer patients without incurring side effects such as hair loss and vomiting is being developed.
The method, produced at the University of Bath, involves using tiny fibres and beads soaked in the chemotherapy drug, which are then implanted into the cancerous area in the patient’s body.
The product is called Fibrasorb. These fibres are biodegradable and compatible with body tissue, which means they would not be rejected by the patient’s body. They gradually turn from solid to liquid, releasing a regular flow of the chemotherapy chemical into the cancer site, and a much lower dose to the rest of the body.
This is a more localised way of killing cancer cells than the current method of injecting the chemical into a cancer sufferer’s vein so that it is carried around the body. The first clinical trials on volunteer patients are expected to begin in the next few years.
The first human recipients of laboratory-grown organs were reported in April by Anthony Atala, MD, director of the Institute for Regenerative Medicine at Wake Forest University School of Medicine, United States. In The Lancet, Atala describes long-term success in children and teenagers who received bladders grown from their own cells.
“This is one small step in our ability to go forward in replacing damaged tissues and organs,” said Atala, who is now working to grow 20 different tissues and organs, including blood vessels and hearts, in the laboratory. The engineered bladders were grown from the patients’ own cells, so there is no risk of rejection.
Scientists hope that laboratory- grown organs can one day help solve the shortage of donated organs available for transplantation. Atala reported that the bladders showed improved function over time – with some patients being followed for more than seven years.
The study involved patients from 4 to 19 years old who had poor bladder function because of a congenital birth defect. Atala had been working since 1990 to build bladders from patients’ own cells and in 1999 implanted the first organ in a patient. His current report discusses the long-term results with seven children who had the surgery.
“We wanted to go slowly and carefully and make sure we did it the right way,” said Atala. “This is a small, limited experience, but it has enough followup to show us that tissue engineering is a viable tool that will allow us to tackle problems of similar magnitude.” The process for growing each patient’s organ began with a biopsy to get samples of muscle cells and the cells that line the bladder walls.
These cells were grown in a culture in the laboratory until there were enough cells to place onto a specially constructed biodegradable mold, or scaffold, shaped like a bladder. The cells continued to grow.
Then, seven or eight weeks after the biopsy, the engineered bladders were sutured to patients’ original bladders during surgery. The scaffold was designed to degrade as the bladder tissue integrated with the body. Testing showed that the engineered bladders functioned as well as bladders that are repaired with intestine tissue, but with none of the ill effects.
A scientific review in April's Nutrition Reviews shows that a vegetarian diet is highly effective for weight loss. Vegetarian populations tend to be slimmer than meat-eaters, and they experience lower rates of heart disease, diabetes, high blood pressure, and other lifethreatening conditions linked to overweight and obesity.
The new review, compiling data from 87 previous studies, shows the weightloss effect does not depend on exercise or caloriecounting, and it occurs at a rate of approximately 500 grammes per week.
The authors found that the body weight of both male and female vegetarians is, on average, 3% to 20% lower than that of meateaters. “Our research reveals that people can enjoy unlimited portions of high-fiber foods such as fruits, vegetables, and whole grains to achieve or maintain a healthy body weight without feeling hungry,” says Dr Susan Berkow, PhD, the lead author.
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