Differential protein expression in maize (Zea mays) in response to insect attack

Maize (Zea mays) is a major food stable in sub-Saharan Africa. However, yields are constrained by insect pests. Insect feeding induces a number of changes in genes encoding different proteins and the plant’s response can either be direct or indirect, or both. In this study, maize plants were infested with two insects with different feeding strategies (Spodoptera littoralis, chewing insect and Busseola fusca, stem borer) to investigate differential protein expression using the Proteomics technique. Infestation of S. littoralis (3rd instar larvae) resulted in 14 spots being up-regulated and 7 being down-regulated. Similarly, infestation of maize with B. fusca (3rd instar larvae) resulted in 12 spots being up-regulated and 9 spots being down-regulated. Interestingly, of those up-regulated only 9 were common to both insects, with only 4 common to both in terms of down regulation. Infestation of maize with S. littoralis resulted in a greater number of spots being up-regulated and less being down-regulated compared to maize infested with B. fusca. Unfortunately, we were unable to identify the proteins represented by these spots.Key words: Busseola fusca, down-regulation, expression, proteomics, Spodoptera littoralis, up-regulation

Synthetic velocity mapping cardiac MRI coupled with automated left ventricle segmentation

Temporal patterns of cardiac motion provide important information for cardiac disease diagnosis. This pattern could be obtained by three-directional CINE multi-slice left ventricular myocardial velocity mapping (3Dir MVM), which is a cardiac MR technique providing magnitude and phase information of the myocardial motion simultaneously. However, long acquisition time limits the usage of this technique by causing breathing artifacts, while shortening the time causes low temporal resolution and may provide an inaccurate assessment of cardiac motion. In this study, we proposed a frame synthesis algorithm to increase the temporal resolution of 3Dir MVM data. Our algorithm is featured by 1) three attention-based encoders which accept magnitude images, phase images, and myocardium segmentation masks respectively as inputs; 2) three decoders that output the interpolated frames and corresponding myocardium segmentation results; and 3) loss functions highlighting myocardium pixels. Our algorithm can not only increase the temporal resolution 3Dir MVMs, but can also generates the myocardium segmentation results at the same time

Influence of right coronary artery motion, flow pulsatility and non-Newtonian rheology on wall shear stress metrics

The patchy distribution of atherosclerosis within the arterial system is consistent with a controlling influence of hemodynamic wall shear stress (WSS). Patterns of low, oscillatory and transverse WSS have been invoked to explain the distribution of disease in the aorta. Disease of coronary arteries has greater clinical importance but blood flow in these vessels may be complicated by their movement during the cardiac cycle. Previous studies have shown that time average WSS is little affected by the dynamic geometry, and that oscillatory shear is influenced more. Here we additionally investigate effects on transverse WSS. We also investigate the influence of non-Newtonian blood rheology as it can influence vortical structure, on which transverse WSS depends; Carreau-Yasuda models were used. WSS metrics were derived from numerical simulations of blood flow in a model of a moving right coronary artery which, together with a subject-specific inflow waveform, was obtained by MR imaging of a healthy human subject in a previous study. The results confirmed that time average WSS was little affected by dynamic motion and that oscillatory WSS was more affected. They additionally showed that transverse WSS and its non-dimensional analogue, the Cross Flow Index, were affected still further. This appeared to reflect time-varying vortical structures caused by the changes in curvature. The influence of non-Newtonian rheology was significant with some physiologically realistic parameter values, and hence may be important in certain subjects. Dynamic geometry and non-Newtonian rheology should be incorporated into models designed to produce maps of transverse WSS in coronary arteries

Magnetic resonance imaging: Physics basics for the cardiologist

Magnetic resonance imaging physics can be a complex and challenging topic for the practising cardiologist. Its evolving nature and the increasing number of novel sequences used in clinical scanning have been topics of excellent reviews; however, the basic understanding of physics underlying the creation of images remains difficult for many cardiologists. In this review, we go back to the basic physics theories underpinning magnetic resonance and explain their application and use in achieving good quality cardiac imaging, whilst describing established and novel magnetic resonance sequences. By understanding these basic principles, it is anticipated that cardiologists and other health professionals will then appreciate more advanced physics manuscripts on cardiac scanning and novel sequences

Cardiovascular magnetic resonance artefacts

The multitude of applications offered by CMR make it an increasing popular modality to study the heart and the surrounding vessels. Nevertheless the anatomical complexity of the chest, together with cardiac and respiratory motion, and the fast flowing blood, present many challenges which can possibly translate into imaging artefacts. The literature is wide in terms of papers describing specific MR artefacts in great technical detail. In this review we attempt to summarise, in a language accessible to a clinical readership, some of the most common artefacts found in CMR applications. It begins with an introduction of the most common pulse sequences, and imaging techniques, followed by a brief section on typical cardiovascular applications. This leads to the main section on common CMR artefacts with examples, a short description of the mechanisms behind them, and possible solutions

Cardiovascular magnetic resonance myocardial perfusion: methods and applications in patients with coronary artery disease

Perfusion CMR is an attractive imaging modality that is becoming comparable with other clinically diagnostic tests. SPECT and PET are well clinically validated and have good accuracy for detection of significant CAD. However, these techniques have a rather low spatial resolution and are not suitable for the detection of subendocardial perfusion defect. In addition, the radiation burden, the potential for attenuation artefacts (SPECT) and the limited availability (PET) are limitations of these imaging techniques. An integrated assessment of myocardial perfusion, function and viability is feasible with CMR. In addition, compared to other clinically available imaging techniques, CMR perfusion has excellent spatial resolution and no ionising radiation exposure. However, it is not widely available and there is a need of protocol and pulse sequence standardization. Most perfusion analysis remains observer-dependent (“eyeball” analysis) or dependent on bolus dispersion (semi-quantitative analysis). Fully quantitative analysis using CMR perfusion is currently time-consuming for clinical application. Perfusion CMR is an evolving field with numerous future directions