Microbot motors fit to swim human arteries
A range of complex surgical operations necessary to treat stroke victims, confront hardened arteries or address blockages in the bloodstream are about to be made safer as researchers from the Micro/Nanophysics Research Laboratory at Australia’s Monash University put the final touches to the design of micro-motors small enough to be injected into the human bloodstream.
A research paper, published 20 January, in Journal of Micromechanics and Microengineering details how researchers are harnessing piezoelectricity, the energy force most commonly used to trigger-start a gas stove, to produce microbot motors just 250 micrometres, a quarter of a millimetre, wide.
Methods of minimally invasive surgery, such as keyhole surgery and a range of operations that utilise catheters are preferred by surgeons and patients because of the damage avoided when contrasted against cut and sew operations. Serious damage during minimally invasive surgery is however not always avoidable and surgeons are often limited by, for example, the width of a catheter tube which, in serious cases, can fatally puncture narrow arteries.
Remote controlled miniature robots small enough to swim up arteries could save lives by reaching parts of the body, like a stroke-damaged cranial artery, that catheters have previously been unable to traverse. With the right sensor equipment attached to the microbot motor, the surgeon’s view of, for example, a patient’s troubled artery can be enhanced and the ability to work remotely also increases the surgeon’s dexterity.
As Professor James Friend, leader of the research team at Monash University, explained, motors have lagged behind in the age of technological miniaturisation and provide the key to making robots small enough for injection into the bloodstream. “If you pick up an electronics catalogue, you’ll find all sorts of sensors, LEDs, memory chips, etc that represent the latest in technology and miniaturisation. Take a look however at the motors and there are few changes from the motors available in the 1950s.”
Professor Friend and his team began their research over two years ago in the belief that piezoelectricity was the most suitable energy force for micromotors because the engines can be scaled down while remaining forceful enough, even at the sizes necessary to enter the bloodstream, for motors to swim against the blood’s current and reach spots difficult to operate upon.
The team has produced prototypes of the motors and is now working on ways to improve the assembly method and the mechanical device which moves and controls the micro-motors.
Images showing bleeding heart after heart attack
Images that for the first time show bleeding inside the heart after people have suffered a heart attack have been captured by scientists, in a new study published January in the journal Radiology.
The research shows that the amount of bleeding can indicate how damaged a person’s heart is after a heart attack. The researchers, from the MRC Clinical Sciences Centre at Imperial College London, hope that this kind of imaging will be used alongside other tests to create a fuller picture of a patient’s condition and their chances of recovery.
Recent research has shown that some people experience bleeding inside the heart muscle once blood starts to pump into it again. However, the significance of this bleeding is currently not understood.
The researchers used MRI to capture the new images. They were able to detect the area of bleeding because of the magnetic effects of iron, which is present in the blood.
For the new small study, the researchers captured images of bleeding inside the heart in 15 patients from Imperial College Healthcare NHS Trust who had recently suffered a heart attack, using MRI. Analysis of the MRI scans revealed that the amount of bleeding correlated with how much damage the heart muscle had sustained.
Arterial blood flow and the efficacy of stents
Reperfusion therapy in the form of percutaneous coronary intervention (PCI) is now the recommended first treatment for victims of acute myocardial infarction. New European guidelines issued in November 2008 emphasised speed of action and the importance of reperfusion therapy to restore blood flow to the heart and improve survival rates. The benefits of PCI are less clear in patients with stable coronary artery disease; PCI has been shown to improve symptoms, but the impact on prognosis is still a matter of debate.
The cornerstone of PCI is the technique of angioplasty, by which either bare-metal or drug-releasing stents are located within the coronary arteries at points of occlusion. The FAME study, reported in the 15 January 2009 issue of the New England Journal of Medicine, was a randomised trial designed to assess the most effective method of locating the stent in patients with multivessel disease: conventional angiography (visualisation of the artery) or a new technique of “fractional flow reserve” (FFR), by which a tiny wire with a sensor is threaded through the coronary artery to the point of occlusion and blood flow measured to determine if the lesion is restricting blood flow and causing ischemia.
The study, conducted in 20 European and US centres, randomised more than 1,000 patients with multivessel coronary disease to either of the two methods for placement of stents. Results showed that one-third fewer stents were used in the FFR group and the difference in composite outcome at one year was significant: the FFR group showed a 28% lower incidence of major adverse cardiac events (repeat angioplasty, heart attack or death) - 18.3% vs. 13.2%.
The implication in these results is that placing stents in lesions not responsible for ischemia is not only unnecessary, but may cause worse outcomes.
Commenting on the study on behalf of the European Society of Cardiology, Professor Uwe Zeymer from the Herzzentrum, Ludwigshafen, Germany, said that, while PCI is clearly beneficial for the relief of symptoms in patients with stable angina, the prognostic impact of PCI in the patient group in this study is still a matter of debate. One reason for this, he explained, may be that some stent procedures are performed solely on the basis of “oculo stenotic reflex” (the visual presence of a stenosis).
However, he added: “One method which is easy to perform and readily available during diagnostic angiography is measurement of the fractional flow reserve, a method which can distinguish between hemodynamically relevant and irrelevant stenoses. The latter do not need intervention and can be safely treated with medical therapy. The FAME study has now shown that by using FFR we can improve the prognosis of patients and reduce the number of unnecessary interventions. As a result, this method should be used in patients with stable symptoms and without documentation of ischemia by another method. In patients with multivessel disease in particular, FFR can increase the safety and efficacy of coronary revascularisation. In addition, FFR seems cost effective and avoids unnecessary and potentially harmful interventions.”
Nicotine receptors on tongue
Researchers in Portugal and the US have found for the first time nicotine receptors in the taste buds. In fact, although most of the toxicity of smoking is linked to other components, it is nicotine that leads to smoking addiction and until now it was believed that this substance had to migrate into the brain – where its specific receptors existed – to provoke its effects. This new discovery published in the Proceedings of the National Academy of Sciences (PNAS) reveals a second recognition pathway most probably contributing to addiction and suggesting a possible new target for antismoking drugs. The added bonus is that on this route the drugs can be applied topically (on the tongue), drastically reducing their side effects. This novel pathway is also shown to activate a brain area that when damaged can lead to instant loss of smoking addiction suggesting that mouth nicotine receptors can play a key role in the whole dependence process.
● Proceedings of the National Academy of Sciences (PNAS ) - January 2009 online Early Edition, “Nicotine activates TRPM5-dependent and independent taste pathways”
First embryonic stem cell therapy trial in man approved
The world’s first clinical trial of human embryonic stem cell (hESC)-based therapy in man has been approved by the US Food and Drug Administration (FDA).
Geron Corporation has been granted clearance to begin a Phase I multi-centre trial for an investigational new drug OPC1 in patients with acute spinal cord injury – in the thoracic spinal cord.
Thomas Okarma, PhD, MD, Geron's president and CEO, said the trial “marks the beginning of what is potentially a new chapter in medical therapeutics – one that reaches beyond pills to a new level of healing: the restoration of organ and tissue function achieved by the injection of healthy replacement cells.
“The ultimate goal for the use of OPC1 is to achieve restoration of spinal cord function by the injection of hESCderived oligodendrocyte progenitor cells directly into the lesion site of the patient’s injured spinal cord.”
Okarma says investigators hope to begin enrolling the first patients mid-year this year.
OPC1 contains hESC-derived oligodendrocyte progenitor cells that have demonstrated remyelinating and nerve growth stimulating properties leading to restoration of function in animal models of acute spinal cord injury (Journal of Neuroscience, Vol. 25, 2005).
Although the primary endpoint of the trial is safety, the protocol includes secondary endpoints to assess efficacy, such as improved neuromuscular control or sensation in the trunk or lower extremities. Once safety in this patient population has been established and the FDA reviews clinical data in conjunction with additional data from ongoing animal studies, Geron plans to seek FDA approval to extend the study to increase the dose of OPC1, enrol subjects with complete cervical cord injuries and expand the trial to include patients with severe incomplete (ASIA grade B or C) injuries to enable access to the therapy for as broad a population of severe spinal cordinjured patients as is medically appropriate.
Sensor in artery measures blood pressure
For hypertensive patients, the traditional method of measuring blood pressure is a tedious process: Patients have to wear a small case containing the blood pressure meter close to their body. An inflatable sleeve on their arm records their blood pressure values, for which it is regularly pumped up and deflated. This is a burden on the patients, particularly at night. The whole process is now due to become easier thanks to a tiny implant that could replace the current method. It is being developed by Fraunhofer researchers together with the company Dr Osypka and other partners in a BMBF-funded project called “Hyper-IMS” (Intravascular Monitoring System for Hypertension Patients).
“A doctor introduces the pressure sensor directly into the femoral artery in the groin,” explains head of department Dr Hoc Khiem Trieu of the Fraunhofer Institute for Microelectronic Circuits and Systems IMS in Duisburg, Germany. “The sensor, which has a diameter of about one millimeter including its casing, measures the patient’s blood pressure 30 times per second. It is connected via a flexible microcable to a transponder unit, which is likewise implanted in the groin under the skin. This unit digitizes and encodes the data coming from the microsensor and transmits them to an external reading device that patients can wear like a cell phone on their belt. From there, the readings can be forwarded to a monitoring station and analysed by the doctor.” Because the researchers use special components in CMOS technology, the system requires little energy. The micro-implants can be supplied with electricity wirelessly via coils.
Implantable pressure sensors are also suitable for other applications, such as monitoring patients suffering from cardiac insufficiency. The researchers are currently performing the first clinical trials.
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