Regional myocardial oxygen tension: 19F MRI of sequestered perfluorocarbon

A novel noninvasive method of measuring local myocardial oxygen tension (pO₂) In the perfused rat heart using ¹⁹F MRI is demonstrated. Tissue pO₂ was determined on the basis of the ¹⁹F spin-lattice relaxation rate (R1) of perflubron (perfluorooctyl bromide) sequestered in the heart after IV infusion of an emulsion. Spectroscopic measurement of R1 was previously used to measure a global weighted average of oxygen status. ¹⁹F MRI now provides 3D spatial resolution indicating local cardiac pO₂ under normally perfused, globally ischemic, and regionally ischemic conditions.     

The Cbl family of ubiquitin ligases: critical negative regulators of tyrosine kinase signaling in the immune system

The Cbl family of proteins are evolutionarily conserved negative regulators of activated tyrosine kinase-coupled receptors. Antigen receptors are prominent targets of negative regulation by the Cbl family members, Cbl and Cbl-b, which proteins function as ubiquitin ligases. Cbl and Cbl-b contain substrate recognition domains that interact specifically with activated protein tyrosine kinases of the Src and Syk/ZAP-70 families. Cbl-mediated ubiquitination of these kinases leads to their degradation, resulting in attenuation of receptor signals. Cbl may also control activation-induced monoubiquitination of antigen receptors, thus facilitating their delivery to lysosomes for subsequent degradation. Finally, the interactions of Cbl proteins with downstream targets of tyrosine kinases, such as PI-3-kinase and Vav, could provide an additional mechanism to attenuate receptor signaling. By targeting multiple components of antigen receptor signaling for degradation, the Cbl protein family provides a critical mechanism to ensure an appropriate immune response. The hyperresponsiveness of Cbl(-/-) and Cbl-b(-/-) lymphocytes and the autoimmune phenotype of Cbl-b(-/-) mice lend strong support for this proposal. The ability to control early receptor signals through regulated protein degradation provides a novel paradigm of immunoregulation.     

Internal mammary perforators: a cadaver study

Microsurgeons currently employ the internal mammary artery and vein as recipient vessels for microvascular reconstruction of the breast with increasing frequency. Recent reports have demonstrated that the perforating branches of the internal mammary artery and vein can also be used as recipient vessels. The purpose of the following cadaver study was to determine the location and diameter of these internal mammary perforators and whether they are suitable as recipient vessels. Ten fresh cadavers were obtained for this project. Using a micrometer under loupe magnification, bilateral measurements were taken of the perforators from the first five interspaces. The largest arterial perforator averaged 1.74 mm in diameter and the largest venous perforator averaged 1.78 mm in diameter. The largest perforators were most commonly found in the second interspace. Based on the results of this study, the internal mammary perforators appear to have suitable diameter for microvascular anastomosis and should be considered.     

Is It Time to Move on from Two-Dimensional Transesophageal to Three-Dimensional Transthoracic Echocardiography for Assessment of Left Atrial Appendage? Review of Existing Literature

Left atrial appendage (LAA) has unique anatomical and physiological properties, which make it a common site for thrombus formation in many cardiovascular and systemic diseases. Assessment of LAA for thrombus thus becomes important in many clinical situations and two-dimensional transesophageal echocardiography (2D TEE), which allows excellent quality images of LAA because of its close proximity to esophagus is routinely used for this purpose. However, it is a semiinvasive procedure, requires more time and involves some degree of patient discomfort. With some training and experience, two-dimensional transthoracic echocardiography (2D TTE) can visualize LAA in most patients with good acoustic windows. A disadvantage of both 2D TTE and 2D TEE is that they provide only a thin slice or section of cardiac structures at any given time limiting their utility in comprehensively assessing the LAA for thrombus. On the other hand, live/real time three-dimensional (3D) TTE overcomes this limitation of both 2D TTE and 2D TEE because of its ability to encompass whole of the LAA in three-dimensions in the acquired data set, which can then be cropped and sectioned systematically at any desired angulation to more definitively look for clot. 3D TTE is also useful in differentiating a clot from pectinate muscles in the LAA, which can mimic a thrombus resulting in patient mismanagement. In addition, 3D TTE is helpful in sectioning a clot for lysis, which has implications in clot resolution. We reviewed the existing literature comparing the relative advantages and disadvantages of 3D TTE versus 2D TEE and found that in patients with good acoustic windows 3D TTE had similar efficacy for detecting LAA thrombus. (Echocardiography 2012;29:112-116)     

Real Time Three-Dimensional Echocardiography for the Evaluation of Cardiomyopathy

Cardiomyopathy refers to a set of diseases that are characterized by myocardial dysfunction. Classically, two-dimensional echocardiography has been used in the diagnosis of these disorders and to help guide their management. Three-dimensional transthoracic echocardiography is now increasingly being used in the diagnosis, management, and prognostication of intrinsic cardiomyopathies. In this article, we summarize the available data on the use of three-dimensional transthoracic echocardiography in various forms of intrinsic cardiomyopathy as well as some of its advantages over traditional two-dimensional transthoracic echocardiography. (Echocardiography 2012;29:76-87)     

Zidovudine for treating AIDS

For additional diagnostic clues, Dr Morris recommends looking at the eyes. Many systemic diseases, including diabetes mellitus, thyroid disease, and AIDS, have characteristic ocular manifestations. These often can be seen with tools readily available to primary care physicians. This article sheds light on the role of ocular findings in the evaluation of systemic disease.     

Hugh Cairns and the origin of British neurosurgery

Sir Hugh Cairns, the first Nuffield Professor of Surgery in Oxford and consultant neurosurgeon to the Royal Army Medical Corps during World War II, was a leader in helping to establish neurosurgery as a speciality in Britain. After learning the craft from Dr Harvey Cushing in Boston, Cairns fought against the general surgical orthodoxy in London to establish the first specialised neurosurgical unit in a teaching hospital. We review his early life, training with Cushing, his inspiring character and administrative prowess which not only helped to win the battle for neurosurgery in London but also helped to establish the Oxford Clinical School and to save thousands of lives during the Second World War.