47 research outputs found
MRA of the Aorta and Peripheral Arteries
No full textIt can be argued that magnetic resonance angiography of the aorta and peripheral vessels has undergone more dramatic changes over the last couple decades than any other form of cardiovascular magnetic resonance imaging. The first useful clinical applications primarily used two-dimensional time-of-flight technology. However, in the mid-1990s, this approach was replaced to a large degree by contrast-enhanced techniques using conventional agents in dynamic, multiphase mode. Blood pool agents have also been developed for use in magnetic resonance angiography, but their precise role remains to be determined. Given the risks of gadolinium contrast in patients with renal failure, which is not an unusual concomitant in patients undergoing vascular evaluation, there has been a recent resurgence in interest in the use of non-contrast magnetic resonance angiographic approaches
Aortic Aneurysm and Pseudoaneurysm Assessment
No full textAlthough contrast angiography is still considered the “gold standard” for evaluation of the aorta and its major branches, Magnetic Resonance Angiography (MRA) has quickly gained popularity as an imaging tool for the assessment of the entire aorta. MRA serves as an alternative imaging modality that can be utilized in patients with impaired renal function and with allergies to iodinated contrast medium (iodinated contrast medium is required in contrast angiography and computed tomography, CT). The purpose of this unit is to present fundamental MRA techniques useful in the evaluation of the thoracic and abdominal aorta based on experience on a 1.5 T GE LX scanner.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/145258/1/cpmia1202.pd
Characterisation of the Scs system that confers copper tolerance in Salmonella enterica serovar Typhimurium
No full textGram-negative bacteria have a variety of systems that catalyse the formation of disulphide bonds, which are essential for the folding, activity, and stability of many periplasmic and secreted proteins. The scsABCD (suppressor of copper sensitivity) locus of Salmonella enterica encodes four proteins with thioredoxin-like catalytic motifs. Previous work has shown that Salmonella encounters toxic levels of copper during infection and the scs system provides protection against copper-mediated toxicity. Given that Cu2+ ions are known to promote disulphide oxidation, it was hypothesised that the StScs proteins and copper both influence the thiol redox status of periplasmic proteins in vivo. The current work reports that expression of the soluble periplasmic protein StScsC is copper-specific, and copper was found to oxidise StScsC in vivo. Using a combination of genetic and proteomics approaches, the abundance of various cysteine-containing periplasmic/secreted proteins were found to be elevated by StScsC and copper in the Salmonella periplasm. Copurification and mass spectrometry approaches provide additional evidence that the arginine-sensing periplasmic protein ArtI interacts with StScsC. Intramacrophage survival data demonstrates that loss of StScsC results in a significant decrease in survival. The current work reports a new role for the thioredoxin-like StScsC protein in disulphide folding of ArtI, a periplasmic L-arginine sensing protein. Given the known impact of arginine sensing/uptake upon c-di-GMP signalling and the production of nitric oxide (NO) by host cells, the current work demonstrates a role for the Scs system in facilitating intramacrophage survival through alleviating copper-stress, and implicates StScsC in a broader role in immune evasion.
In addition, the presence of StScs proteins and copper was shown to increase the yield of Herceptin Fab fragments (used to treat breast cancer) in the E. coli periplasm. Hence, the StScs proteins have the potential to facilitate the formation of disulphides in protein therapeutics that can be used in biotechnological platforms.
This work provides novel insights into the in vivo role for the Scs system in Salmonella, and highlights the importance of disulphide stress responses and copper tolerance during infection
Multislice T1‐weighted hybrid rare in CNS imaging: Assessment of magnetization transfer effects and artifacts
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CT and MR imaging of the thoracic aorta: current techniques and clinical applications.
No full textDisease of the thoracic aorta can present with a broad clinical spectrum of symptoms and signs. The accepted diagnostic gold standard, selective digital subtraction angiography, is now being challenged by state-of-the-art CT angiography (CTA) and MR angiography(MRA). Currently, in many centers, cross-sectional imaging modalities are being used as the first line of diagnosis to evaluate the cardiovascular system, and conventional angiography is reserved for therapeutic intervention. Understanding the principles of CTA and MRA techniques is essential to acquire diagnostic images consistently. This article reviews current CTA and MRA methods used in the evaluation of thoracic aortic disease
