The team, led by Clement Hamani, aimed to alter the 50-year-old man’s feeding behavior and treat his obesity by electrically stimulating the hypothalamus, the area of the brain that helps to regulate certain metabolic processes.
The subject was awake but anesthetized during the procedure; DBS electrodes were implanted into both sides of the hypothalamus and potential sites were identified by asking the patient to score between 1 and 10 how hungry he felt when stimulated. The electrodes were then secured in position and a pulse generator was also implanted. In-depth neurological assessments were made at the time of the surgery and, 3 weeks later, ‘on–off’ tests were also performed so the subject did not know when the electrodes were switched on. They also performed radiological testing after 1 month of DBS to see which areas of the brain were being activated by the stimulation.
They unexpectedly found that when stimulated to a certain threshold, at a certain point on the hypothalamus, the subject reported a feeling of déjà vu and feeling like he was 20 years old again, in a park with friends and his girlfriend from when he was that age. As the voltage was increased, the details of the memories became clearer and more intense. Associative memory tasks found that stimulation increased recollection but not familiarity-based recognition. At 3 weeks after surgery there were significant improvements on two of the verbal and spatial learning tests, compared with the scores at the time of surgery. The radiological testing showed that hypothalamic stimulation in this subject modulated activity in the mesial temporal lobe and influenced memory functions.
In the first 6 months of DBS at high frequency there was no change in the weight of the subject but when a lower frequency was used, the patient lost 12 kg over 5 months; he experienced reduced food cravings and had a decreased tendency to binge with stimulation. However, during the last 4 months of the study, the patient purposely turned the stimulator off and his night-time binging returned and he put back on all of his lost weight.
This study has accidentally found some very surprising and encouraging results regarding memory recall and has shown that it may be possible to modulate memory function by applying electrical stimulation to various areas of the brain.
Sources: www.nhs.uk/News/Pages/NewsIndex.aspx Hamani C, McAndrews MP, Cohn M et al. Memory enhancement induced by hypothalamic/fornix deep brain stimulation. Ann. Neurol. 63, 119–123 (2008).
Doctors able to feel organs using a display screen
Erik Vidholm at the Center for Image Analysis at Uppsala University (Sweden) has been involved in developing a new technology that uses computerized image analysis to determine the size of organs, or to construct 3D models of organs when surgery or radiation is being planned. It is thought to be a future possibility for a 3D mouse to be used so doctors can feel their images.
Modern imaging techniques are improving all the time and the resulting images can be very complex and difficult to interpret. The Center for Image Analysis is just one institution that is trying to establish better methods for exploration and analysis of these images for both diagnostic and treatment planning purposes.
One of the interactive methods that is being developed by the team involves the mouse and keyboard being replaced by a pen-like 3D mouse, which enables the user to feel the virtual organs. Computer models can be adapted to the images of organs and can then be used to measure the volume and shape of the organ, for example.
Source: www.uu.se/news
PET better at detecting treatment response
CT and MRI scans provide anatomical images of the area being scanned, whereas PET imaging shows the biological functioning of the region in real time.
The response of a solid tumor to treatment is currently evaluated using Response Evaluation Criteria in Solid Tumors (RECIST); CT or MRI scans before and after treatment are compared to find the change in tumor size. The RECIST criteria grades the tumor as either stable disease, progressive disease, complete response, or partial response.
If conventional imaging and evaluation fails to accurately show response to treatment, successful therapies may be discontinued. If a patient is not responding, using PET scanning to evaluate response could help prevent them from undergoing toxic therapies that are not working.
“We knew from our considerable experience with neoadjuvant therapy (treatment before surgery) in sarcoma patients, that measuring tumor size correlated poorly with response,” said Dr Fritz Eilber, Assistant Professor of Surgery, Director of the Sarcoma Program at UCLA’s Jonsson Cancer Center and senior author of the study. “We have removed many tumors that have not changed in size with treatment or have even grown, but are completely dead on pathologic analysis. Just because the tumor doesn’t shrink doesn’t mean the treatment didn’t work.”
The aim of the study was to evaluate whether PET with 18F-fluorodeoxyglucose (FDG-PET), which measures sugar metabolism in cells, allows for a more accurate evaluation of histopathologic response. A total of 42 patients with biopsy-proven high-grade soft-tissue sarcoma had a FDG-PET/CT scan before and after neoadjuvant treatment. Changes in tumor FDG uptake and size from the baseline to the follow-up scan were calculated. The scanner used in this study combines two imaging modalities in one machine, allowing the researchers to directly compare the scans for tumor size (measured by CT) and metabolic activity (PET).
“PET was much more sensitive in picking up response than size-based RECIST,” Eilber said. “RECIST missed a large percentage of patients that actually had a response. PET picked up all of the responders.”
This study raises questions about the way tumors are monitored during and after treatment. Patients should not undergo unnecessary treatment or be removed from therapies that are working. Eilber and colleagues are working to confirm their results in a larger study and testing new metabolic tracers to assess treatment response.
Sources: www.cancer.mednet.ucla.edu Evilevitch V, Weber WA, Eilber FC et al. Reduction of glucose metabolic activity is more accurate than change in size at predicting histopathologic response to neoadjuvant therapy in high-grade soft-tissue sarcoma. Clin. Cancer Res. 14, 715–720 (2008).
New adhesive modeled on a gecko’s foot
Engineers at the University of California, Berkeley (CA, USA), have developed a new adhesive inspired by the sticky feet of geckos, which have the ability to climb vertical walls and ceilings. Whereas standard tape or glue sticks to a surface when pressed onto it, this new adhesive sticks as it slides onto a surface and lifts off with minimal force and no residue.
The material is made from millions of plastic fibers that establish grip; 42 million hard plastic microfibers were squeezed onto each square centimeter. The microfibers are made of polypropylene, and are 20 µm long and 0.6 µm in diameter.
They found that on a smooth, clean, vertical surface, two square centimeters of the adhesive could hold 400 g. The structure is similar to a microfiber array developed by the same group in 2006. That material relied upon friction to work but required the application of force to make it stick. Changes made to the plastic backing enabled the directional adhesion reported in this new material to work on truly vertical surfaces.
What sets this new gecko-inspired adhesive apart from others created so far is that it is directional, only ‘sticking’ when it slides along a smooth surface, not when it is pressed down.
“This difference is critical because if you’re climbing up vertical surfaces, you can’t afford to use a lot of energy pressing down into the surface to stick,” said coauthor, Professor Ron Fearing. “Using force to attach also requires force to detach. A gecko running uphill may be attaching and detaching its feet 20 times a second, so it’d get very tired if it had to work hard to pull its feet off at every step.”
Similar to gecko fiber arrays, the synthetic patch maintains contact and increases shear force with sliding. The high shear force observed (∼210 nN per fiber) suggests that fibers are in side contact, providing a larger true contact area than would be obtained by tip contact. Shear force increased over the course of repeated tests, suggesting deformation of fibers into more favorable conformations.
So far the new adhesive only works on smooth clean surfaces so the next aim of the team is to develop the material so that it can adhere to rough surfaces and that it is self-cleaning.
Sources: http://newscenter.berkeley.edum Lee J, Majidi C, Schubert B, Fearing R. Sliding induced adhesion of stiff polymer microfiber arrays: 1. Macroscale behaviour. J. Royal Soc. Interface (10.1098/rsif.2007.1308)
Better medical device information needed to help patients and doctors
“These days, patients are asking their doctors for the newest technologies from genetic tests to specific radiation treatments, and many physicians don’t know where to turn for the latest evidence-based information,” commented Mitchell D. Feldman, Professor of Medicine at UCSF (CA, USA) and corresponding author of the study. “Sometimes, the only information out there is what the manufacturer provides.”
The team suggests that after US FDA approval has been obtained for a new medical device, an ‘evidence based’ technology assessment should be conducted by an independent organization to ensure that the devices are in fact safe and beneficial, and to provide data that can increase awareness of “the potential promise and pitfalls of new technology”, the team writes.
The analysis from the UCSF evaluated the federal review process, the method by which devices come to market, how the scientific literature reports on clinical trials involving medical devices, and the effectiveness of independent review boards in improving a technology’s medical benefit to patients. They found that out of the thousands of medical technology applications submitted annually to the FDA, less than 100 undergo the kind of scrutiny that is required for new drugs. It is also reported that the agency relies on manufacturers and clinical investigators to initiate recalls and failure reports when a technology has been revealed to be not beneficial or is potentially harmful to patients.
“FDA approval should be the start of the process toward clinical application, not the end,” Feldman said. “Physicians and patients just aren’t aware of the limitations of the FDA process of initial assessment and oversight of new medical technologies. Assessments by objective entities are a necessary addition to FDA approval – so that deficiencies in clinical evidence, and patient safety issues that may arise after approval, are recognized before widespread adoption into clinical practice.”
One example of an independent review organization that should be involved in the medical device review process is the California Technology Assessment Forum (CTAF; CA, USA), which was profiled in the report by the UCSF team. The CTAF is a community forum that is dedicated to objectivity and transparency regarding medical technologies; a community forum for dialog and decisions regarding the safety and effectiveness of new and emerging technologies.
Sources: http://pub.ucsf.edu www.ctaf.org
Robotic technique to improve hip surgery training
Device: Acrobot® Navigation System
Subjects (n): 32
Indication: Surgical navigation
Professor Justin Cobb, Head of the Biosurgery and Surgical Technology Group at Imperial College London (UK), has conducted a trial on 32 undergraduate medical students to test whether planning before an operation, combined with the latest navigation equipment, could increase the success rates of students practicing hip resurfacing arthroplasty procedures, a method to correct hip bone deformities by coating the femoral head with a chrome alloy cast.
Until now inexperienced surgeons have only been able to learn and gain the necessary experience to carry out hip resurfacing operations by repeatedly performing the operations, risking the need for painful and expensive corrective operations for patients.
The tested navigation tool was Acrobot Navigation, which is similar to a GPS tracking system. It helps the surgeon to navigate during surgery by plotting correct surgical incisions and calculating the correct angles for inserting chrome alloy parts needed to repair hip bones.
The tried and tested device has two digital arms protruding from a console. One arm senses the movement of surgical tools, the other takes detailed images of the bones. Information is fed into software, generating a virtual model of a patient’s hip as it is being operated on, allowing the user to plot the progress of an operation as it is being performed, which is a vital technique for ensuring that it is being carried out correctly.
Source: www.imperial.ac.uk/news
Biodegradable film to reduce scarring after heart surgery
Device: REPEL-CV® Adhesion Barrier
Patients (n): 103
Indication: Surgical scarring
REPEL-CV® Adhesion Barrier is a bioabsorbable adhesion barrier film that is designed to be placed over the surface of the heart at the conclusion of a surgical procedure. The presence of REPEL-CV on the surface of the heart is intended to block the transmission of fibrin, a blood component and, thereby, prevent the formation of fibrous bands of scar tissue, known as adhesions, between the surface of the heart and surrounding tissue surfaces.
Scarring can be a troublesome occurrence when multiple surgeries are required to treat a patient. It is a normal part of the healing process but makes follow-up surgeries much more difficult and lengthy.
“With adhesions, we have to cut through tough, fibrous tissue in very delicate areas – not just between the heart and the sternum, but also in other areas between vessels and cardiac chambers… Often the scarring is severe enough that when we perform a second surgery, we find the heart is stuck to the sternum… This increases the amount of time a patient has to be under anesthesia and potentially could involve more bleeding and the need for transfusion or other blood products,” says Dr Andrew Lodge, Pediatric Cardiothoracic Surgeon at Duke University Medical Center (NC, USA) and study leader. “So we are very interested in anything that can keep scarring to a minimum.”
Adhesions represent a significant complication in secondary open heart surgical procedures in that they make it difficult to visualize and access the heart. The removal of these adhesions is an essential but tedious and risky process, which can extend the length of the surgical procedure by up to 60 min. This additional time in surgery translates into added cost as well as greater risk to the patient due to the extended exposure to anesthesia.
Many other methods and materials have been tried and tested but REPEL-CV looks very promising. “…if we use anything we usually use a nonabsorbable membrane made of Gore-Tex that we place between the heart and the sternum, but it’s not ideal” says Lodge, anything foreign that’s left in the body can provoke an inflammatory response or invite infection and “that’s why the idea of an absorbable film is so attractive.”
The study, presented at the Society of Thoracic Surgeons annual meeting, involved 103 infants at 15 institutions around the USA undergoing open heart surgery that were expected to undergo a second procedure. Half of the infants were randomly assigned to the treatment group with the REPEL-CV and the others served as controls. They found that the use of the REPEL-CV dramatically reduced the incidence of severe scarring and no side effects were noted from the use of the film. The product has not yet been approved by the FDA, although an application for approval has been accepted.
Sources: www.dukemednews.org/home www.physorg.com www.synthemed.com