Scientists at University College London (UCL) have shown that the human brain holds and continuously updates an internal map of the body. The team hope their findings will help explain how such processes in the brain may go wrong in people with neurological or psychiatric disorders.
Using volunteers, researchers found that their brains rapidly adjusted the processing of touch information to match information from proprioception – the position of the limbs relative to the body. They used a method called tendon vibration to distort volunteers’ sense of their own body.
When the biceps tendon of the right arm was vibrated, volunteers felt within seconds that their right elbow was rotating away from the body, even though the arm was quite still. If the volunteers held their left index finger with their right hand while this happened they felt their left index finger getting longer as they felt their arm move. The team then tested how these bodily illusions rearranged the body’s sense of touch.
While touching volunteers with two metal rods on worldwide monitor Update from around the globe the left index finger, scientists asked them to judge whether the distance between the rods was greater or smaller than the distance between two additional rods touched on the forehead.
When tendon vibrated the index finger seem longer than it really was, causing volunteers to overestimate the tactile distance on the index finger relative to the forehead.
Professor Patrick Haggard says: “We know that the brain holds a long-term body image which specifies the shape and size of the limbs. However, the stimulation our bodies receive from clothes and the objects we touch changes all the time; the brain needs to keep track of this. Our study shows that the brain has a more dynamic, short-term representation of the body – a constantly updating internal map – which gives us a sense of our body as a coherent self.”
The study was recently published in Current Biology.
A University of Bologna investigation published in the July-August issue of Psychother Psychosom suggests that antidepressant drugs may be over-prescribed in primary care.
Patients from 361 primarycare physicians (PCPs) were evaluated and their psychiatric diagnosis was established by 'unaided' PCPs plus a research interview for depression. PCPs recognised 79.4% of cases of depression and prescribed antidepressants to 40.9% of them. Yet, 45% of patients labelled as depressed by the PCPs were not cases of depression according to international diagnostic criteria. Antidepressants were prescribed for 26.9% of the false-positive cases. Globally 35% of antidepressants for 'depression' were prescribed to false-positive cases.
Genes are more important than exercise in determining response to cholesterol, claims a recent study of twins.
Researchers at the US Department of Energy's Lawrence Berkeley National Laboratory and the Children's Hospital Oakland Research Institute (CHORI), analysed how "bad" cholesterol (low-density lipoprotein, or LDL cholesterol) responded to diets that were either high or low in fat in 28 pairs of identical male twins – one twin a vigorous exerciser, the other a comparative couch potato.
For six weeks the twins ate either a high-fat diet (40% of its calories from fat) or a lowfat diet (only 20 % of calories from fat); then the pairs switched diets for another six weeks. After each period the twins' blood cholesterol levels were tested.
The researchers found an astounding 0.7 correlation in responses to the change in diet, an incredibly strong similarity in the way each pair of twins responded – even though the responses themselves among different pairs of twins differed considerably. The correlations showed that the twins had very similar changes in LDL cholesterol because they had the same genes.
Some twins had one or more genes that made them very sensitive to the amount of fat in their diets. Other twins had genes that made them insensitive to dietary fat, no matter how much they exercised. Williams hopes his findings will inspire additional research to identify the specific genes involved. "Concordant lipoprotein and weight responses to dietary fat change in identical twins with divergent exercise levels," appears in the 8 July, 2005, issue of the American Journal of Clinical Nutrition.
A new Bangkok Charter for Health Promotion was been adopted on 11 August by participants at the 6th Global Conference on Health Promotion, co-hosted by the World Health Organisation (WHO) and the Ministry of Public Health of Thailand.
It identifies major challenges, actions and commitments needed to address the determinants of health in a globalised world by engaging the many actors and stakeholders critical to achieving health for all.
The Charter highlights the changing context of global health and the challenges faced in achieving its aims, including the growing double burden of communicable and chronic diseases which include heart disease, stroke, cancer and diabetes.
There is also the need to address and harness the health effects of globalisation such as widening inequities, rapid urbanisation and the degradation of environments. The Bangkok Charter gives new direction to Health Promotion by calling for policy coherence, investment and partnering across governments, international organisations, civil society and the private sector to work towards four key commitments.
These include ensuring that health promotion is central to the global development agenda, that it is a core responsibility of all governments and part of good corporate practice, as well as a focus of community and civil society initiatives.
• The Bangkok Charter for Health Promotion www.who.int/healthpromotion/co nferences/6gchp/bangkok_charter
Diabetic kidney failure
Certain gene variants predispose diabetics to the development of kidney failure, according to Heidelbergbased geneticists working in collaboration with diabetes experts from Mannheim, the Netherlands and the Czech Republic.
It is hoped the finding will become the basis for developing gene tests to gauge individual risk. Some 40% of all diabetics develop chronic kidney failure, mainly due to their genetic disposition.
In the August issue of Diabetes, Heidelberg geneticist Dr. Bart Janssen and his colleagues describe the socalled CNDP1-gene on chromosome 18 which is responsible for the production of the enzyme carnosinase.
This enzyme splits the mini protein carnosine which the researchers found can prevent kidney cell damage when present at high concentrations in the blood. “High quantities of carnosine are always found when low quantities of carnosinase are present,” says Janssen. How much carnosinase is produced depends in turn on the number and combination of DNA bases within the gene CNDP1.
The longer the gene, the less carnosinase is produced. In their latest publication the Heidelberg geneticists describe three different variants of the gene, the longest containing 2,191 DNA bases and presumably the most active one with the highest production of carnosinase enzyme.
The other two variants contain 2,188 to 2,185 bases. The shortest variant has a very low enzyme production. As expected carriers have a low level of carnosinase. Likewise, the scientists found that diabetics without kidney involvement mainly have this shortened variant of the gene.
Longer genes are mainly found in patients suffering from diabetic nephropathy. The risk of developing kidney failure can presumably be predicted by a simple gene test. Research on the development of this test is underway.
A hormone found in the small intestine has provided a crucial breakthrough in developing new drugs to tackle the growing obesity epidemic, scientists claim.
In an article published in Diabetes, a team from Imperial College London and Hammersmith Hospitals NHS Trust used injections of oxyntomodulin, a naturally occurring digestive hormone found in the small intestine, to reduce body weight and calorific intake in overweight volunteers.
The injections boost existing levels of oxyntomodulin, normally released from the small intestine as food is consumed, signalling to the brain that the body has had enough to eat. Professor Steve Bloom, senior researcher, says: “Not only is oxyntomodulin naturally occurring, it has virtually no side effects and could be ideal for general use as it can be self administered.
Despite this, we still need to conduct larger clinical trials to test its effectiveness over longer periods.” The researchers found that over four weeks, injections of oxyntomodulin three times a day in 14 volunteers reduced their body weight by an average of 2.3kg.
They also found that daily energy intake by the test group was reduced by an average of 170kcal after the first injection, to 250kcal at the end of four weeks. The researchers also found that volunteers in the study group had lesser appetites without a reduction in food palatability.
The study found that leptin, a protein responsible for regulating the body's energy expenditure was reduced in the study group. They also found reduced levels of adipose hormones, a hormone which encourages the build up of adipose tissues, a type of tissue where fat cells are stored.
Women suffer more pain
Scientists investigating gender differences in pain have found that women report more pain throughout the course of their lifetime and experience it in more bodily areas, more often and for longer than men.
These conclusions are based on several studies into the pain response of volunteers exposed to a pain stimulus, such as a cold water bath, as well as field studies in clinics and hospitals. Dr Ed Keogh, a psychologist from the Pain Management Unit (PMU) at the University of Bath, United Kingdom, said: “Unfortunately all too often the differences between males and females are not considered in pain research or practice, and instead are either ignored or statistically averaged.”
“While most explanations concentrate on biological mechanisms, such as genetic and hormonal differences, it is becoming increasingly clear that social and psychological factors are also important.”
One example is the different strategies men and women use to cope with pain. While women tend to focus on the emotional aspects of pain, men tend to focus on the sensory aspects. “Women who concentrate on the emotional aspects of their pain may actually experience more pain as a result, possibly because the emotions associated with pain are negative,” said Dr Keogh.
Other research by the PMU looked at the relationship between gender differences in anxiety sensitivity and pain – the tendency to be fearful of anxiety-related sensations (eg, rapidly beating heat). A study of 150 patients referred to a hospital clinic with chest pain revealed again that men and women were different.
|Researchers believe the fear of anxiety-related sensations and an increased tendency to negatively interpret such sensations are more predominant in women than men and influence their experiences of pain.
“Chest pain is associated with coronary heart disease, angina and heart attacks, so it is understandable that chest pain is a cause of great anxiety for patients and that anxiety has an important role in the experience of chest pain,” said Dr Keogh.
Another study showed that interdisciplinary approaches to pain management may have different effects on women than men. Researchers from the PMU assessed 98 patients in chronic pain as they went through a pain management programme involving physiotherapy, psychological treatments and occupational therapy.
While both men and women exhibited a significant reduction in pain intensity both during and immediately after the programme, three months later women reported the same levels of pain as pre-treatment, whereas men’s remained the same as immediately posttreatment. Interestingly, there were improvements in disability in both sexes, which were maintained at follow-up.
Nano diagnostic tool
A portable low-cost molecular detection tool is being developed by a team of European researchers, reports Information Society Technologies (IST).
The tool promises to revolutionise the diagnosis of diseases such as cancer and opens up new applications in sectors as diverse as environmental protection, chemical analysis and food safety. The IST-funded BioFinger project is due to begin testing its state-of-the-art system with a view to a commercial product being available within two to three years.
“What we are creating is a generic, highly precise and highly versatile tool to detect and analyse molecules in the blood and other fluids using nano and micro cantilevers,” explained project co-ordinator Joan Bausells at the Consejo Superior de Investigaciones Cientificas in Spain.
Nano cantilevers, smaller than the surface of a fly’s eye and their larger counterparts, micro cantilevers, act as sensors to detect molecules, providing a way to rapidly and accurately diagnose disease.
When coated with antibodies they bend and resonate to changes in surface tension and mass when fluids containing disease-related protein molecules attach to them. By seeing whether or not the cantilevers react, doctors would be able to determine whether or not a disease is present.
A new ventricular assist device (VAD) called the PediPump has been developed specifically for use in children. A status report on this new device appears in the July issue of the journal Artificial Organs.
Measuring just 7mm by 70 mm, this small rotary dynamic VAD is suitable for use in children, including newborns, in treatment of end-stage heart failure. The programme that developed the PediPump is a partnership between clinicians at The Children’s Hospital at the Cleveland Clinic and researchers in Biomedical Engineering, The Lerner Research Institute of the Cleveland Clinic in the United States.
“Historically, children have had few options for mechanical support of the failing heart,” Dr Brian Duncan, the lead researcher, said. “The experimental development of the PediPump and similar devices will give new hope to children with heart failure.”
According to researchers, despite being much smaller than traditional VADs, the PediPump has demonstrated excellent haemodynamic performance and its versatile design will ultimately allow for its use in a variety of clinical settings. Researchers plan to further reduce the size of the PediPump to allow for a totally implantable paediatric VAD.
New breast cancer research shows for the first time that even women with large breast tumours can benefit from a less invasive biopsy method that has been reserved until now for women with small breast cancers.
Lymphatic mapping and sentinel node biopsy, when used to determine how far the cancer has progressed into the lymph nodes, can help some patients avoid the pain and discomfort of full armpit node removal, which often causes swelling, numbness and infection.
The surgical technique hasn't been used until now in women with large breast tumours because of a lack of data proving its reliability. But the new study from the University of North Carolina at Chapel Hill School of Medicine, USA, may provide that research evidence.
The findings, published in the September issue of the American Journal of Surgery, show that sentinel node biopsy, when performed before chemotherapy is given to shrink the tumour, is very reliable, the UNC researchers said.
The study suggests that sentinel node biopsy is an option that might benefit all women with breast cancers, said Dr David Ollila, the study's lead author. Dr Ollila is an associate professor of surgery at UNC and a member of the UNC Lineberger Comprehensive Cancer Center.
A key obstacle to early detection of type 1 diabetes – as well as to rapid assessment of the effectiveness of therapeutic intervention – has been the lack of direct, non-invasive technologies to visualise inflammation in the pancreas, an early manifestation of disease.
Instead, clinicians have had to await overt symptoms before diagnosing an individual, by which time destruction of the insulin-producing beta cells of the pancreas has already progressed significantly. Recent proof-of-principle experiments by Joslin Diabetes Center and Massachusetts General Hospital (MGH), USA, researchers, however, offer hope that physicians may one day be able to identify individuals with preclinical type 1 diabetes, and to assess the effectiveness of therapies much earlier than is now possible.
Findings of the study were due to be published in the September issue of the Journal of Clinical Investigation. “The most exciting aspect of this study is that it demonstrates that we can, at least in mice, use a noninvasive imaging method to predict at a very early time whether a drug will stop the progression of diabetes or not. In fact, the drug we used in these proof-of-principle experiments is analogous to one currently being tried in humans with diabetes, and so far showing great promise,” said Diane Mathis, PhD, who led the study.
In this study, the Joslin and MGH researchers used a new imaging technique to reveal the otherwise undetectable inflammation of pancreatic islets in recently diagnosed diabetic mice. As T lymphocytes invade the pancreas, blood vessels swell, become more permeable, and leak fluid – as well as small molecules carried in the fluid – into surrounding tissues.
In previous experiments, the researchers demonstrated that this leakage can be detected with the help of magnetic nanoparticles (MNP) and magnetic resonance imaging (MRI). After being injected intravenously, these MNPs, which are minute particles of iron oxide, travel through the blood vessels of the body including the pancreas.
If pancreatic vessels have become leaky from inflammation, the magnetic particles spill into nearby tissues, where they are “eaten” by scavenger cells called macrophages. Thus, the MNPs become concentrated at the inflamed site and can be spotted by high-resolution MRI. Results of this study suggest that the MRI-MNP imaging technology may be helpful in identifying people at immediate risk of developing autoimmune diabetes, but most of all for early prediction of response to therapy, which might be very useful for reducing the time and cost of clinical trials.
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