Follow-up analysis at 1 year indicates that thrombus aspiration improves cardiac outcome.
According to results published recently in The Lancet, the initial benefits observed in treating patients with acute myocardial infarction (MI) with thrombus aspiration (TA), rather than conventional percutaneous coronary intervention (PCI), translate into clinical benefit 1 year on.
The TA during Percutaneous coronary intervention in Acute myocardial infarction Study (TAPAS) was initiated to determine whether TA could improve reperfusion following interventions for acute MI. PCI is a standard and successful treatment for heart attack patients. However, spontaneous or angioplasty-induced embolization of atherothrombotic material during the procedure is common, leading to vascular obstruction, larger infarct size and increased mortality. The theoretical benefit of TA prior to stent implantation over traditional PCI is that balloon predilation is unnecessary, meaning stents can be implanted directly.
Initial results from the single-center, randomized trial indicated that TA led to improved myocardial reperfusion compared with conventional PCI; however, investigators were keen to assess whether these promising initial results also produced improved longer term outcomes. Patients enrolled on the trial between January 2005 and December 2006 at the University Medical Center, Groningen, The Netherlands, were randomly assigned to either TA (n = 535) or conventional PCI (n = 536). Of these, data were available on 1060 (99%) at 1-year follow-up. The primary end points of the study were cardiac death or nonfatal reinfarction.
At 1 year, cardiac death had occurred in 3.6% (19 of 535) of patients in the TA group and 6.7% (36 of 536) in the PCI group (hazard ratio [HR]: 1.93; 95% confidence interval [CI]: 1.11–3.37; p = 0.020). When considering 1-year cardiac death or nonfatal reinfarction, this occurred in 5.6% (30 of 535) of the TA and 9.9% (53 of 536) of the PCI group (HR: 1.81; 95% CI: 1.16–2.84; p = 0.009).
The authors concluded that, “Compared with conventional PCI, TA before stenting of the infarcted artery seems to improve the 1-year clinical outcome after PCI for ST-elevation myocardial infarction.”
If, as implied by these initial results, TA significantly improves myocardial perfusion, the technique may influence clinical guidelines and enter the standard approach to patients with acute MI. “We are the first to demonstrate the efficacy of TA in terms of improved clinical outcome. Based on these results, TA will be increasingly utilized in routine clinical practice…” the authors commented.
Source: Vlaar PJ, Svilaas T, van der Horst IC et al. Cardiac death and reinfarction after 1 year in the Thrombus Aspiration during Percutaneous coronary intervention in Acute myocardial infarction Study (TAPAS): a 1-year follow-up study. Lancet 371, 1915–1920 (2008).
Confocal laser endomicroscopy used to diagnose digestive disorders
Scientists from the Johns Hopkins University School of Medicine (MD, USA) have investigated a technique that may speed-up the diagnosis of digestive disorders.
Confocal laser endomicroscopy enables clinicians to view highly magnified images of a patient’s gastrointestinal tract through the attachment of a microscope to an endoscope.
The main benefit of this technology is that it has the potential to reduce the time it takes to diagnose diseases such as inflammatory bowel disease. Kerry Dunbar (Johns Hopkins) explains; “Previously, it took a few days or a week to find out a diagnosis because we’d have to take photos and then do a mucosal biopsy. But with confocal laser endomicroscopy, we can see what’s going on at the time of the endoscopy and then diagnose and treat patients immediately, instead of waiting a week or more.” Gastrointestinal cancers often progress rapidly, therefore prompt detection and treatment is of paramount importance.
The research group performed a confocal laser endomicroscopy examination on 1771 patients with suspected gastrointestinal problems. Traditional diagnostic tests were also carried out. They found it to be 91% accurate at identifying problems in the upper gastrointestinal tract and 93% accurate at identifying problems in the lower gastrointestinal tract. In the study, presented at Digestive Disease Week 2008 in San Diego (CA, USA), 422 patients were correctly diagnosed with gastroesophageal reflux disease, 84 with esophageal cancer, 99 with colon cancer, 75 with gastritis, 22 with stomach cancer, 39 with celiac disease and 893 with inflammatory bowel disease.
Source: 49th Annual Digestive Disease Week, San Diego, CA, USA, 17–22 May, 2008.
Motor mimetics: learning muscle function from toads
Researchers from the Northern Arizona University are studying toads’ feeding motions in an effort to improve the design of electric motors, prostheses and other medical treatments for neuromuscular disorders, such as Parkinson’s disease.
The fast feeding action of toads – their tongues move at high speed to capture prey – offers a fresh perspective to scientists investigating muscle behavior. Muscles are generally thought of as acting like motors, but Kiisa Nishikawa (Northern Arizona University, AZ, USA) suggests they may be more similar to springs.
“When a toad or chameleon captures prey with its tongue, it exerts force over a distance. Figuring out how they do it has immense application to any device that actually moves.”
A group from Arizona State University, led by Tom Sugar, is designing a robotic tendon, focusing in particular on the ankle gait cycle. This group met with Nishikawa to discuss muscle function and the lessons that can be learned from nature. Sugar’s team is hoping to mimic biological function in the storage and release of energy during the ankle gait cycle.
“Energy is stored as the leg and body roll over the ankle, and then this energy is released in a powerful burst to propel the user forward. By mimicking biology, we are able to build a very lightweight and functional device.” commented Sugar.
By studying nature, Nishikawa hopes to learn more about how the brain controls movement and what the contribution of muscle function is. This can then be applied to diseases such as Parkinson’s disease, where identifying the molecular mechanisms involved will help in the development of treatment options.
PET imaging for diagnosis of early head and neck cancer
A study published in the Journal of the National Cancer Institute has investigated the accuracy of PET using the radioactive tracer 18F-fluorodeoxyglucose (18F-FDG PET) in detecting lymph node metastases in patients with head and neck squamous cell carcinoma. This imaging technique has been proposed to enhance the preoperative assessment of cervical lymph node status in this type of carcinoma.
Establishing the presence or absence of spread of the carcinoma to nearby lymph nodes is important in determining the prognosis. There is currently controversy over the use of 18F-FDG PET on patients with a clinically negative (cN0) neck. Such patients appear to be clinically free of metastases in the lymph nodes, but MRI scans, CT scans and FDG-PET are used to confirm this. However, no evidence has conclusively supported the use of 18F-FDG PET in such patients.
A total of 32 studies involving 1236 patients were included in the meta-analysis of all available studies of the diagnostic performance of 18F-FDG PET in patients with head and neck squamous cell carcinoma. The sensitivity and specificity across studies was calculated as well as a summary receiver operating characteristic curves using hierarchical regression models. Where possible, the performance of 18F-FDG PET was compared with that of conventional diagnostic methods, such as CT, MRI and ultrasound with fine-needle aspiration.
The sensitivity and specificity of 18F-FDG PET were found to be 79% (95% CI: 72–85%) and 86% (95% CI: 83–89%), respectively. For cN0 patients, sensitivity of 18F-FDG PET was only 50% (95% CI: 37–63%), whereas specificity was 87% (95% CI: 76–93%).
The authors of the study, from University of Ioannina School of Medicine (Greece), concluded that, “18F-FDG PET has good diagnostic performance in the overall pretreatment evaluation of patients with head and neck squamous carcinoma but still does not detect disease in half of the patients with metastasis and cN0.”
Source: Kyzas PA, Evangelou E, Denaxa-Kyza D, Ioannidis JP. 18F-fluorodeoxyglucose positron emission tomography to evaluate cervical node metastases in patients with head and neck squamous cell carcinoma: a meta-analysis. J. Natl Cancer Inst. 100(10), 712–720 (2008).
Latest medical device: your cell phone?
Latest research sees everyday technology, such as cell phones and email, as a potential medical device.
Data presented at the 55th Annual Meeting of the American College of Sports Medicine demonstrate how investigators are seeking new ways to motivate people to develop healthy habits and assist them with tasks, such as monitoring their blood glucose level, through ‘normal’ devices.
Researchers from the American College of Sports Medicine have developed a prototype cell phone that can also act as a blood glucose monitor and pedometer. Normal blood testing procedures are used to measure blood glucose levels; the micrometer can be plugged into the phone using the phone’s serial port, with a read-out provided on screen. This information can then be sent easily via SMS to a diabetes monitoring center. While this will in no way replace the need for regular check-ups, the researchers hope that feedback provided by the monitoring center can be sent back to the patient, helping them to maintain healthy glucose levels.
“The monitoring center automatically analyzes data sent by the cell phone user,” stated Suyi Li, a member of the research team. “Tailored suggestions and feedback are then sent back to the user. It’s certainly not a substitute for regular physician visits, but can potentially catch complications and provide some motivation for the user to work at getting their glucose levels on track.”
Various other strategies exploiting technology that many people use regularly in the course of their daily lives, such as email, have also been investigated for their health-raising potential. A number of studies have investigated the potential of regular motivational emails to encourage more activity in a variety of populations (e.g., young people and postpartum women). Results suggest that regular emails can more than double the amount of activity undertaken per week.
With Li and colleagues hoping that their cell phone monitoring technology could be available to the public within the next 3–5 years, the role of everyday technology in healthcare is set to increase.
Source: www.acsm.org
MRI to track cells magnetically labeled by bacterial gene
Human cells introduced to a gene from magnetotactic bacteria can produce magnetic particles.
Scientists from Emory University (GA, USA) have been investigating the full potential of the MRI scanner. The group believe that, in addition to generating anatomical images, MRI can be used to provide functional, physiological and molecular information to greatly improve biomedical research and clinical healthcare. The study indicates that a gene expression marker for MRI can be achieved using bacterial magnetosomes. Magnetosomes are magnets produced by naturally occurring magnetotactic bacteria and consist of 15–20 magnetite crystals, with each crystal approximately 35–120 nm long.
The gene magA, found in magnetotactic bacteria and known to be involved with iron transport is expressed in the commonly used human cell line 293FT. Expression of this gene results in the production of magnetic, iron-oxide nanoparticles by these cells and leads to increased transverse relaxivity. The production of these magnetite crystals in human cells allow them to show up on a MRI scan, with the potential for this technology to allow scientists to track the movement of cells through the body.
This study has demonstrated that these nanoparticles can be formed in vivo utilizing endogenous iron and can be used to visualize cells positive for magA. The authors conclude that, “These results demonstrate that magA alone is sufficient to produce magnetic nanoparticles and that it is an appropriate candidate for an MRI reporter gene.”
Xiaoping Hu, Professor of Biomedical Engineering at Emory University, GA, USA and the Georgia Institute of Technology, GA, USA believe magA to be nontoxic, “magA can be thought of as the equivalent of green fluorescent protein, but for magnetic resonance imaging.”
Source: Zurkiya O, Chan AW, Hu X. magA is sufficient for producing magnetic nanoparticle in mammalian cells, making it an MRI reporter. Magn. Reson. Med. 59, 1225–1231 (2008).