Systematic comparison and reconstruction of sea urchin (Echinoidea) internal anatomy: a novel approach using magnetic resonance imaging

<p>Abstract</p> <p>Background</p> <p>Traditional comparative morphological analyses and subsequent three-dimensional reconstructions suffer from a number of drawbacks. This is particularly evident in the case of soft tissue studies that are technically demanding, time-consuming, and often prone to produce artefacts. These problems can partly be overcome by employing non-invasive, destruction-free imaging techniques, in particular micro-computed tomography or magnetic resonance imaging.</p> <p>Results</p> <p>Here, we employed high-field magnetic resonance imaging techniques to gather numerous data from members of a major marine invertebrate taxon, the sea urchins (Echinoidea). For this model study, 13 of the 14 currently recognized high-ranking subtaxa (orders) of this group of animals were analyzed. Based on the acquired datasets, interactive three-dimensional models were assembled. Our analyses reveal that selected soft tissue characters can even be used for phylogenetic inferences in sea urchins, as exemplified by differences in the size and shape of the gastric caecum found in the Irregularia.</p> <p>Conclusion</p> <p>The main focus of our investigation was to explore the possibility to systematically visualize the internal anatomy of echinoids obtained from various museum collections. We show that, in contrast to classical preparative procedures, magnetic resonance imaging can give rapid, destruction-free access to morphological data from numerous specimens, thus extending the range of techniques available for comparative studies of invertebrate morphology.</p

Evaluating the success of total productive maintenance at Faurecia interior systems

Manufacturing processes should operate at optimal levels in order to remain competitive in current economic environment. The optimal manufacturing performance can be achieved by overall equipment efficiency which is also a measurement for Total Productive Maintenance (TPM). The successful implementation of TPM has been evaluated at Faurecia Interior Systems. The research consisted out of a literature review into the elements and benefits of TPM. A questionnaire was sent to all operator level personnel at Faurecia Interior Systems to establish their views on the implementation level of TPM at the East London site. In conclusion, this research paper has also led to the development of recommendations which should improve TPM at the site

The impact of vasomotion on analysis of rodent fMRI data

IntroductionSmall animal fMRI is an essential part of translational research in the cognitive neurosciences. Due to small dimensions and animal physiology preclinical fMRI is prone to artifacts that may lead to misinterpretation of the data. To reach unbiased translational conclusions, it is, therefore, crucial to identify potential sources of experimental noise and to develop correction methods for contributions that cannot be avoided such as physiological noise. Aim of this study was to assess origin and prevalence of hemodynamic oscillations (HDO) in preclinical fMRI in rat, as well as their impact on data analysis.MethodsFollowing the development of algorithms for HDO detection and suppression, HDO prevalence in fMRI measurements was investigated for different anesthetic regimens, comprising isoflurane and medetomidine, and for both gradient echo and spin echo fMRI sequences. In addition to assessing the effect of vasodilation on HDO, it was studied if HDO have a direct neuronal correlate using local field potential (LFP) recordings. Finally, the impact of HDO on analysis of fMRI data was assessed, studying both the impact on calculation of activation maps as well as the impact on brain network analysis. Overall, 303 fMRI measurements and 32 LFP recordings were performed in 71 rats.ResultsIn total, 62% of the fMRI measurements showed HDO with a frequency of (0.20 ± 0.02) Hz. This frequent occurrence indicated that HDO cannot be generally neglected in fMRI experiments. Using the developed algorithms, HDO were detected with a specificity of 95%, and removed efficiently from the signal time courses. HDO occurred brain-wide under vasoconstrictive conditions in both small and large blood vessels. Vasodilation immediately interrupted HDO, which, however, returned within 1 h under vasoconstrictive conditions. No direct neuronal correlate of HDO was observed in LFP recordings. HDO significantly impacted analysis of fMRI data, leading to altered cluster sizes and F-values for activated voxels, as well as altered brain networks, when comparing data with and without HDO.DiscussionWe therefore conclude that HDO are caused by vasomotion under certain anesthetic conditions and should be corrected during fMRI data analysis to avoid bias

Solution structure of the Legionella pneumophila Mip-rapamycin complex

<p>Abstract</p> <p>Background</p> <p><it>Legionella pneumphila </it>is the causative agent of Legionnaires' disease. A major virulence factor of the pathogen is the homodimeric surface protein Mip. It shows peptidyl-prolyl cis/trans isomerase activty and is a receptor of FK506 and rapamycin, which both inhibit its enzymatic function. Insight into the binding process may be used for the design of novel Mip inhibitors as potential drugs against Legionnaires' disease.</p> <p>Results</p> <p>We have solved the solution structure of free Mip^77–213and the Mip^77–213-rapamycin complex by NMR spectroscopy. Mip^77–213showed the typical FKBP-fold and only minor rearrangements upon binding of rapamycin. Apart from the configuration of a flexible hairpin loop, which is partly stabilized upon binding, the solution structure confirms the crystal structure. Comparisons to the structures of free FKBP12 and the FKBP12-rapamycin complex suggested an identical binding mode for both proteins.</p> <p>Conclusion</p> <p>The structural similarity of the Mip-rapamycin and FKBP12-rapamycin complexes suggests that FKBP12 ligands may be promising starting points for the design of novel Mip inhibitors. The search for a novel drug against Legionnaires' disease may therefore benefit from the large variety of known FKBP12 inhibitors.</p

Functional MRI Readouts From BOLD and Diffusion Measurements Differentially Respond to Optogenetic Activation and Tissue Heating

Functional blood-oxygenation-level-dependent (BOLD) MRI provides a brain-wide readout that depends on the hemodynamic response to neuronal activity. Diffusion fMRI has been proposed as an alternative to BOLD fMRI and has been postulated to directly rely on neuronal activity. These complementary functional readouts are versatile tools to be combined with optogenetic stimulation to investigate networks of the brain. The cell-specificity and temporal precision of optogenetic manipulations promise to enable further investigation of the origin of fMRI signals. The signal characteristics of the diffusion fMRI readout vice versa may better resolve network effects of optogenetic stimulation. However, the light application needed for optogenetic stimulation is accompanied by heat deposition within the tissue. As both diffusion and BOLD are sensitive to temperature changes, light application can lead to apparent activations confounding the interpretation of fMRI data. The degree of tissue heating, the appearance of apparent activation in different fMRI sequences and the origin of these phenomena are not well understood. Here, we disentangled apparent activations in BOLD and diffusion measurements in rats from physiological activation upon sensory or optogenetic stimulation. Both, BOLD and diffusion fMRI revealed similar signal shapes upon sensory stimulation that differed clearly from those upon heating. Apparent activations induced by high-intensity light application were dominated by T2∗-effects and resulted in mainly negative signal changes. We estimated that even low-intensity light application used for optogenetic stimulation reduces the BOLD response close to the fiber by up to 0.4%. The diffusion fMRI signal contained T2, T2∗ and diffusion components. The apparent diffusion coefficient, which reflects the isolated diffusion component, showed negative changes upon both optogenetic and electric forepaw stimulation. In contrast, positive changes were detected upon high-intensity light application and thus ruled out heating as a major contributor to the diffusion fMRI signal

Dietary fat intake and red blood cell fatty acid composition of children and women from three different geographical areas in South Africa

Dietary fat intake, particularly the type of fat, is reflected in the red blood cell (RBC) fatty acid (FA) profile and is vital in growth, development and health maintenance. The FA profile (%wt/wt) of RBC membrane phospholipids (as determined by gas chromatography) and dietary intake (as determined by 24 h recall) was assessed in 2–6 y old South African children and their caregivers randomly selected from three communities, i.e. an urban Northern Cape community (urban-NC; n = 104), an urban coastal Western Cape community (urban-WC; n = 93) and a rural Limpopo Province community (rural-LP; n = 102). Mean RBC FA values across groups were compared using ANOVA and Bonferroni post-hoc test while controlling for age and gender (children); median dietary intake values were compared using a Kruskal–Wallis test. Dietary intakes for total fat, saturated FAs and polyunsaturated FAs were higher in the two urban areas compared to the rural area. Total fat intake in rural-LP, and omega-3 FA dietary intake in all three areas were lower than the South African adopted guidelines. Dietary SFA intake in both urban areas was higher than recommended by South African guidelines; this was reflected in the RBC membrane FA profile. Rural-LP children had the lowest intake of omega-3 and omega-6 FAs yet presented with the highest RBC docosahexaenoic acid (DHA) profile and highest arachidonic acid percentage. Although differences observed in dietary fat intake between the two urban and the rural area were reflected in the RBC membrane total phospholipid FA profile, the lowest total fat and α-linolenic acid (ALA) intake by rural children that presented with the highest RBC DHA profile warrants further investigation.IS

Cardiac-respiratory self-gated cine ultra-short echo time (UTE) cardiovascular magnetic resonance for assessment of functional cardiac parameters at high magnetic fields

Background: To overcome flow and electrocardiogram-trigger artifacts in cardiovascular magnetic resonance (CMR), we have implemented a cardiac and respiratory self-gated cine ultra-short echo time (UTE) sequence. We have assessed its performance in healthy mice by comparing the results with those obtained with a self-gated cine fast low angle shot (FLASH) sequence and with echocardiography. Methods: 2D self-gated cine UTE (TE/TR = 314 μs/6.2 ms, resolution: 129 × 129 μm, scan time per slice: 5 min 5 sec) and self-gated cine FLASH (TE/TR = 3 ms/6.2 ms, resolution: 129 × 129 μm, scan time per slice: 4 min 49 sec) images were acquired at 9.4 T. Volume of the left and right ventricular (LV, RV) myocardium as well as the end-diastolic and -systolic volume was segmented manually in MR images and myocardial mass, stroke volume (SV), ejection fraction (EF) and cardiac output (CO) were determined. Statistical differences were analyzed by using Student t test and Bland-Altman analyses. Results: Self-gated cine UTE provided high quality images with high contrast-to-noise ratio (CNR) also for the RV myocardium (CNRblood-myocardium = 25.5 ± 7.8). Compared to cine FLASH, susceptibility, motion, and flow artifacts were considerably reduced due to the short TE of 314 μs. The aortic valve was clearly discernible over the entire cardiac cycle. Myocardial mass, SV, EF and CO determined by self-gated UTE were identical to the values measured with self-gated FLASH and showed good agreement to the results obtained by echocardiography. Conclusions: Self-gated UTE allows for robust measurement of cardiac parameters of diagnostic interest. Image quality is superior to self-gated FLASH, rendering the method a powerful alternative for the assessment of cardiac function at high magnetic fields.</p