Citric acid cycle flux and pressure-volume work in the isolated working rat heart

It has been demonstrated previously that the mammalian heart cannot sustain physiologic levels of pressure-volume work if ketone bodies are the only substrates for respiration. In order to determine the metabolic derangement responsible for contractile failure in hearts utilizing ketone bodies, rat hearts were prefused at a near-physiologic workload in a working heart apparatus with acetoacetate and competing or alternate substrates including glucose, lactate, pyruvate, propionate, leucine, isoleucine, valine and acetate. While the pressure-volume work for hearts utilizing glucose was stable for 60 minutes of perfusion, performance fell by 30 minutes for hearts oxidizing acetoacetate as the sole substrate. The tissue content of 2-oxoglutarate and its transamination product, glutamate, were elevated in hearts utilizing acetoacetate while succinyl-CoA was decreased suggesting impaired flux through the citric acid cycle at the level of 2-oxoglutarate dehydrogenase. Further studies indicated that the inhibition of 2-oxoglutarate dehydrogenase developed prior to the onset of contractile failure and that the inhibition of the enzyme may be related to sequestration of the required cofactor, coenzyme A, as the thioesters acetoacetyl-CoA and acetyl-CoA. The contractile failure was not observed when glucose, lactate, pyruvate, propionate, valine or isoleucine were present together with acetoacetate, but the addition of acetate or leucine to acetoacetate did not improve performance indicating that improved performance is not mediated through the provision of additional acetyl-CoA. Furthermore, addition of competing substrates that improved function did not relieve the inhibition of 2-oxoglutarate dehydrogenase and actually resulted in the further accumulation of citric acid cycle intermediates "upstream" of 2-oxoglutarate dehydrogenase (2-oxoglutarate, glutamate, citrate and malate). Studies with (1-$\sp{14}$C) pyruvate indicate that the utilization of ketone bodies is associated with activation of NADP$\sp+$dependent malic enzyme and enrichment of the C4 pool of the citric acid cycle. The results suggest that contractile failure induced by ketone bodies in rat heart results from inhibition of 2-oxoglutarate dehydrogenase and that reversal of contractile failure is dissociated from relief of the inhibition, but rather is due to the entry of carbon units into the citric acid cycle as compounds other than acetyl-CoA. This mechanism of enrichment (anaplerosis) provides oxaloacetate for condensation with acetyl-CoA derived from ketone bodies allowing continued energy production by sustaining flux through a span of the citric acid cycle up to the point of inhibition at 2-oxoglutarate dehydrogenase for energy production thereby producing the reducing equivalents necessary to sustain oxidative phosphorylation. ^

Essentials of forensic post-mortem MR imaging in adults

Post-mortem MR (PMMR) imaging is a powerful diagnostic tool with a wide scope in forensic radiology. In the past 20 years, PMMR has been used as both an adjunct and an alternative to autopsy. The role of PMMR in forensic death investigations largely depends on the rules and habits of local jurisdictions, availability of experts, financial resources, and individual case circumstances. PMMR images are affected by post-mortem changes, including position-dependent sedimentation, variable body temperature and decomposition. Investigators must be familiar with the appearance of normal findings on PMMR to distinguish them from disease or injury. Coronal whole-body images provide a comprehensive overview. Notably, short tau inversion–recovery (STIR) images enable investigators to screen for pathological fluid accumulation, to which we refer as “forensic sentinel sign”. If scan time is short, subsequent PMMR imaging may be focussed on regions with a positive forensic sentinel sign. PMMR offers excellent anatomical detail and is especially useful to visualize pathologies of the brain, heart, subcutaneous fat tissue and abdominal organs. PMMR may also be used to document skeletal injury. Cardiovascular imaging is a core area of PMMR imaging and growing evidence indicates that PMMR is able to detect ischaemic injury at an earlier stage than traditional autopsy and routine histology. The aim of this review is to present an overview of normal findings on forensic PMMR, provide general advice on the application of PMMR and summarise the current literature on PMMR imaging of the head and neck, cardiovascular system, abdomen and musculoskeletal system.

Mitral valve replacement in patients under 65 years of age: mechanical or biological valves?

PURPOSE OF REVIEW There is controversy regarding the optimal choice of prosthetic valves in patients less than 65 years of age requiring mitral valve replacement (MVR). Recently, trends for valve replacement are moving towards biological prosthesis also in younger patients, which is justified by the fact that a later valve-in-valve procedure is feasible in the case of degeneration of the tissue valve. This strategy is increasingly recommended in aortic valve surgery but is questionable for MVR. The purpose of this review is to evaluate current guidelines and analyse evidence for biological MVR in patients under 65 years. RECENT FINDINGS There are differences between guidelines of the American Heart Association and those of the European Society of Cardiology concerning the choice of prostheses in patients undergoing MVR. Although the European Society of Cardiology recommends a mechanical mitral valve in patients under 65 years of age, the American Heart Association does not provide detailed advice for these patients. Mitral valve replacement with biological valves in patients under 65 years is associated with higher rates of reoperation due to structural valve deterioration. In addition, several studies showed a decreased survival after biological MVR. SUMMARY Evidence for biological MVR in patients less than 65 years without comorbidities or contraindication for oral anticoagulation does not exist. Recommendations for patients less than 65 years of age should not be blurred by current 'en-vogue' methods for promising but not yet proven valve-in-valve strategies.

Cardiac-specific ablation of synapse-associated protein SAP97 in mice decreases potassium currents but not sodium current

BACKGROUND Membrane-associated guanylate kinase (MAGUK) proteins are important determinants of ion channel organization in the plasma membrane. In the heart, the MAGUK protein SAP97, encoded by the DLG1 gene, interacts with several ion channels via their PDZ domain-binding motif and regulates their function and localization. OBJECTIVE The purpose of this study was to assess in vivo the role of SAP97 in the heart by generating a genetically modified mouse model in which SAP97 is suppressed exclusively in cardiomyocytes. METHODS SAP97(fl/fl) mice were generated by inserting loxP sequences flanking exons 1-3 of the SAP97 gene. SAP97(fl/fl) mice were crossed with αMHC-Cre mice to generate αMHC-Cre/SAP97(fl/fl) mice, thus resulting in a cardiomyocyte-specific deletion of SAP97. Quantitative reverse transcriptase-polymerase chain reaction, western blots, and immunostaining were performed to measure mRNA and protein expression levels, and ion channel localization. The patch-clamp technique was used to record ion currents and action potentials. Echocardiography and surface ECGs were performed on anesthetized mice. RESULTS Action potential duration was greatly prolonged in αMHC-Cre/SAP97(fl/fl) cardiomyocytes compared to SAP97(fl/fl) controls, but maximal upstroke velocity was unchanged. This was consistent with the decreases observed in IK1, Ito, and IKur potassium currents and the absence of effect on the sodium current INa. Surface ECG revealed an increased corrected QT interval in αMHC-Cre/SAP97(fl/fl) mice. CONCLUSION These data suggest that ablation of SAP97 in the mouse heart mainly alters potassium channel function. Based on the important role of SAP97 in regulating the QT interval, DLG1 may be a susceptibility gene to be investigated in patients with congenital long QT syndrome.

Hemodynamic Performance of Edwards Intuity Valve in a Compliant Aortic Root Model

Numerous designs of bioprosthetic valves exist. The sutureless surgical valve is a newer design concept which combines elements of the transcatheter valve technology with surgical valves. This design aims at shorter and easier implantation. It was the aim of this study to perform hemodynamic and kinematic measurements for this type of valves to serve as a baseline for following studies which investigate the effect of the aortic root on the valve performance. To this end, the Edwards Intuity aortic valve was investigated in a new in vitro flow loop mimicking the left heart. The valve was implanted in a transparent, compliant aortic root model, and the valve kinematics was investigated using a high speed camera together with synchronized hemodynamic measurements of pressures and flows. The valve closure was asynchronous (one by one leaflet), and the valve started to close before the deceleration of the fluid. The aortic root model showed a dilation of the sinuses which was different to the ascending aorta, and the annulus was found to move towards the left ventricle during diastole and towards the aorta during systole.

Quantification of Mitral Regurgitation with Multiple Jets: In Vitro Comparison of Two-dimensional PISA techniques

Purpose: Traditionally, the proximal isovelocity surface area (PISA) is based on the assumption of a single hemisphere (hemispheric PISA), but this technique has not been validated for the quantification of mitral regurgitation (MR) with multiple jets. Methods: The left heart simulator was actuated by a pulsatile pump at various stroke amplitudes. The regurgitant volume (Rvol) passing through the mitral valve phantoms with single and double regurgitant orifices of varying size and interspace was quantified by a flowmeter as reference technique. Color Doppler 3-D full-volumes were obtained, and Rvol were derived from 2-D PISA surfaces on the basis of hemispheric and hemicylindric assumption with one base (partial hemicylindric PISA) or 2 bases (total hemicylindric PISA). Results: 72 regurgitant volumes (Rvol range: 8 to 76 ml/beat) were obtained. Hemispheric PISA Rvol correlated well with reference Rvol by one orifice (R²=0.97; bias -2.7±3.2ml), but less by ≥ one orifice (R²=0.89). When a fusion of two PISAs occured, addition of two hemispheric PISA overestimated Rvol (bias 9.1±12.2ml, fig.1), and single hemispheric PISA underestimated Rvol (bias -12.4±4.9ml). If an integrated approach was used (hemispheric in single orifice, total hemicylindric in two non-fused PISAs and partial hemicylindric in two fused PISAs), the correlation was R²=0.95, bias -1.6±5.6ml (fig.2). In the ROC analysis, the cutoff to detect ≥ moderate-to-severe Rvol (≥45ml) was 42ml (AUC 0.99, sens. 100%, spec. 93%). Conclusions: In MR with two regurgitant jets, the 2-D hemicylindric assumption of the PISA offers a better quantification of Rvol than the hemispheric assumption. Quantification of MR using 2-D PISA requires an integrated approach that considers number of regurgitant orifices and fusion of the PISAs.

[Ventricular assist device – Possibilities of long-term mechanical circulatory support]

In Switzerland 200’000 people suffer from congestive heart failure. Approximately 10’000 patients find themselves in an advanced state of the disease. When conservative treatment options are no longer available heart transplantation is the therapy of choice. Should this not be an option due to long waiting lists or medical issues assist device therapy becomes an option. Assist device therapy is separated in short-term and long-term support. Long-term support is nowadays performed with ventricular assist devices (VADs). The native heart is still in place and supported in parallel to the remaining function of the heart. The majority of patients are treated with a left ventricular assist device (LVAD). The right ventrical alone (RVAD) as well as bi-ventricular support (BiVAD) is rarely needed. The modern VADs are implantable and create a non-pulsative bloodflow. A percutaneous driveline enables energy supply and pump-control. Indication strategies for VAD implantations include bridge to transplant (short term support), bridge to candidacy and bridge to transplant. VADs become more and more a definite therapeutic option (destination therapy). VAD therapy might be a realistic alternative to organ transplantation in the near future.

Functional Characterization and Comparison of Intercellular Communication in Stem Cell-Derived Cardiomyocytes

One novel treatment strategy for the diseased heart focuses on the use of pluripotent stem cell-derived cardiomyocytes (SC-CMs) to overcome the heart's innate deficiency for self-repair. However, targeted application of SC-CMs requires in-depth characterization of their true cardiogenic potential in terms of excitability and intercellular coupling at cellular level and in multicellular preparations. In this study, we elucidated the electrical characteristics of single SC-CMs and intercellular coupling quality of cell pairs, and concomitantly compared them with well-characterized murine native neonatal and immortalized HL-1 cardiomyocytes. Firstly, we investigated the electrical properties and Ca2+ signaling mechanisms specific to cardiac contraction in single SC-CMs. Despite heterogeneity of the new cardiac cell population, their electrophysiological activity and Ca2+ handling were similar to native cells. Secondly, we investigated the capability of paired SC-CMs to form an adequate subunit of a functional syncytium and analyzed gap junctions and signal transmission by dye transfer in cell pairs. We discovered significantly diminished coupling in SC-CMs compared with native cells, which could not be enhanced by a coculture approach combining SC-CMs and primary CMs. Moreover, quantitative and structural analysis of gap junctions presented significantly reduced connexin expression levels compared with native CMs. Strong dependence of intercellular coupling on gap junction density was further confirmed by computational simulations. These novel findings demonstrate that despite the cardiogenic electrophysiological profile, SC-CMs present significant limitations in intercellular communication. Inadequate coupling may severely impair functional integration and signal transmission, which needs to be carefully considered for the prospective use of SC-CMs in cardiac repair.

Dual antiplatelet therapy duration after coronary stenting in clinical practice: results of an EAPCI survey

AIMS Our aim was to report on a survey initiated by the European Association of Percutaneous Cardiovascular Interventions (EAPCI) concerning opinion on the evidence relating to dual antiplatelet therapy (DAPT) duration after coronary stenting. METHODS AND RESULTS Results from three randomised clinical trials were scheduled to be presented at the American Heart Association Scientific Sessions 2014 (AHA 2014). A web-based survey was distributed to all individuals registered in the EuroIntervention mailing list (n=15,200) both before and after AHA 2014. A total of 1,134 physicians responded to the first (i.e., before AHA 2014) and 542 to the second (i.e., after AHA 2014) survey. The majority of respondents interpreted trial results consistent with a substantial equipoise regarding the benefits and risks of an extended versus a standard DAPT strategy. Two respondents out of ten believed extended DAPT should be implemented in selected patients. After AHA 2014, 46.1% of participants expressed uncertainty about the available evidence on DAPT duration, and 40.0% the need for clinical guidance. CONCLUSIONS This EAPCI survey highlights considerable uncertainty within the medical community with regard to the optimal duration of DAPT after coronary stenting in the light of recent reported trial results. Updated recommendations for practising physicians to guide treatment decisions in routine clinical practice should be provided by international societies.

Detection of haemorrhagic shock: Are vital signs obsolete? A commentary by Dr M. Luginbühl

The ATLS program by the American college of surgeons is probably the most important globally active training organization dedicated to improve trauma management. Detection of acute haemorrhagic shock belongs to the key issues in clinical practice and thus also in medical teaching. (In this issue of the journal William Schulz and Ian McConachrie critically review the ATLS shock classification Table 1), which has been criticized after several attempts of validation have failed [1]. The main problem is that distinct ranges of heart rate are related to ranges of uncompensated blood loss and that the heart rate decrease observed in severe haemorrhagic shock is ignored [2]. Table 1. Estimated blood loos based on patient's initial presentation (ATLS Students Course Manual, 9th Edition, American College of Surgeons 2012). Class I Class II Class III Class IV Blood loss ml Up to 750 750–1500 1500–2000 >2000 Blood loss (% blood volume) Up to 15% 15–30% 30–40% >40% Pulse rate (BPM) <100 100–120 120–140 >140 Systolic blood pressure Normal Normal Decreased Decreased Pulse pressure Normal or ↑ Decreased Decreased Decreased Respiratory rate 14–20 20–30 30–40 >35 Urine output (ml/h) >30 20–30 5–15 negligible CNS/mental status Slightly anxious Mildly anxious Anxious, confused Confused, lethargic Initial fluid replacement Crystalloid Crystalloid Crystalloid and blood Crystalloid and blood Table options In a retrospective evaluation of the Trauma Audit and Research Network (TARN) database blood loss was estimated according to the injuries in nearly 165,000 adult trauma patients and each patient was allocated to one of the four ATLS shock classes [3]. Although heart rate increased and systolic blood pressure decreased from class I to class IV, respiratory rate and GCS were similar. The median heart rate in class IV patients was substantially lower than the value of 140 min−1 postulated by ATLS. Moreover deterioration of the different parameters does not necessarily go parallel as suggested in the ATLS shock classification [4] and [5]. In all these studies injury severity score (ISS) and mortality increased with in increasing shock class [3] and with increasing heart rate and decreasing blood pressure [4] and [5]. This supports the general concept that the higher heart rate and the lower blood pressure, the sicker is the patient. A prospective study attempted to validate a shock classification derived from the ATLS shock classes [6]. The authors used a combination of heart rate, blood pressure, clinically estimated blood loss and response to fluid resuscitation to classify trauma patients (Table 2) [6]. In their initial assessment of 715 predominantly blunt trauma patients 78% were classified as normal (Class 0), 14% as Class I, 6% as Class II and only 1% as Class III and Class IV respectively. This corresponds to the results from the previous retrospective studies [4] and [5]. The main endpoint used in the prospective study was therefore presence or absence of significant haemorrhage, defined as chest tube drainage >500 ml, evidence of >500 ml of blood loss in peritoneum, retroperitoneum or pelvic cavity on CT scan or requirement of any blood transfusion >2000 ml of crystalloid. Because of the low prevalence of class II or higher grades statistical evaluation was limited to a comparison between Class 0 and Class I–IV combined. As in the retrospective studies, Lawton did not find a statistical difference of heart rate and blood pressure among the five groups either, although there was a tendency to a higher heart rate in Class II patients. Apparently classification during primary survey did not rely on vital signs but considered the rather soft criterion of “clinical estimation of blood loss” and requirement of fluid substitution. This suggests that allocation of an individual patient to a shock classification was probably more an intuitive decision than an objective calculation the shock classification. Nevertheless it was a significant predictor of ISS [6]. Table 2. Shock grade categories in prospective validation study (Lawton, 2014) [6]. Normal No haemorrhage Class I Mild Class II Moderate Class III Severe Class IV Moribund Vitals Normal Normal HR > 100 with SBP >90 mmHg SBP < 90 mmHg SBP < 90 mmHg or imminent arrest Response to fluid bolus (1000 ml) NA Yes, no further fluid required Yes, no further fluid required Requires repeated fluid boluses Declining SBP despite fluid boluses Estimated blood loss (ml) None Up to 750 750–1500 1500–2000 >2000 Table options What does this mean for clinical practice and medical teaching? All these studies illustrate the difficulty to validate a useful and accepted physiologic general concept of the response of the organism to fluid loss: Decrease of cardiac output, increase of heart rate, decrease of pulse pressure occurring first and hypotension and bradycardia occurring only later. Increasing heart rate, increasing diastolic blood pressure or decreasing systolic blood pressure should make any clinician consider hypovolaemia first, because it is treatable and deterioration of the patient is preventable. This is true for the patient on the ward, the sedated patient in the intensive care unit or the anesthetized patients in the OR. We will therefore continue to teach this typical pattern but will continue to mention the exceptions and pitfalls on a second stage. The shock classification of ATLS is primarily used to illustrate the typical pattern of acute haemorrhagic shock (tachycardia and hypotension) as opposed to the Cushing reflex (bradycardia and hypertension) in severe head injury and intracranial hypertension or to the neurogenic shock in acute tetraplegia or high paraplegia (relative bradycardia and hypotension). Schulz and McConachrie nicely summarize the various confounders and exceptions from the general pattern and explain why in clinical reality patients often do not present with the “typical” pictures of our textbooks [1]. ATLS refers to the pitfalls in the signs of acute haemorrhage as well: Advanced age, athletes, pregnancy, medications and pace makers and explicitly state that individual subjects may not follow the general pattern. Obviously the ATLS shock classification which is the basis for a number of questions in the written test of the ATLS students course and which has been used for decades probably needs modification and cannot be literally applied in clinical practice. The European Trauma Course, another important Trauma training program uses the same parameters to estimate blood loss together with clinical exam and laboratory findings (e.g. base deficit and lactate) but does not use a shock classification related to absolute values. In conclusion the typical physiologic response to haemorrhage as illustrated by the ATLS shock classes remains an important issue in clinical practice and in teaching. The estimation of the severity haemorrhage in the initial assessment trauma patients is (and was never) solely based on vital signs only but includes the pattern of injuries, the requirement of fluid substitution and potential confounders. Vital signs are not obsolete especially in the course of treatment but must be interpreted in view of the clinical context. Conflict of interest None declared. Member of Swiss national ATLS core faculty.

Population-level risks of physical activity: Saving bones and screening hearts

Documented risks of physical activity include reduced bone mineral density at high activity volume, and sudden cardiac death among adults and adolescents. Further illumination of these risks is needed to inform future public health guidelines. The present research seeks to 1) quantify the association between physical activity and bone mineral density (BMD) across a broad range of activity volume, 2) assess the utility of an existing pre-screening questionnaire among US adults, and 3) determine if pre-screening risk stratification by questionnaire predicts referral to physician among Texas adolescents. ^ Among 9,468 adults 20 years of age or older in the National Health and Nutrition Examination Survey (NHANES) 2007-2010, linear regression analyses revealed generally higher BMD at the lumbar spine and proximal femur with greater reported activity volume. Only lumbar BMD in women was unassociated with activity volume. Among men, BMD was similar at activity beyond four times the minimum volume recommended in the Physical Activity Guidelines. These results suggest that the range of activity reported by US adults is not associated with low BMD at either site. ^ The American Heart Association / American College of Sports Medicine Preparticipation Questionnaire (AAPQ) was applied to 6,661 adults 40 years of age or older from NHANES 2001-2004 by using NHANES responses to complete AAPQ items. Following AAPQ referral criteria, 95.5% of women and 93.5% of men would be referred to a physician before exercise initiation, suggesting little utility for the AAPQ among adults aged 40 years or older. Unnecessary referral before exercise initiation may present a barrier to exercise adoption and may strain an already stressed healthcare infrastructure. ^ Among 3181 athletes in the Texas Adolescent Athlete Heart Screening Registry, 55.2% of boys and 62.2% of girls were classified as high-risk based on questionnaire answers. Using sex-stratified contingency table analyses, risk categories were not significantly associated with referral to physician based on electrocardiogram or echocardiogram, nor were they associated with confirmed diagnoses on follow-up. Additional research is needed to identify which symptoms are most closely related to sudden cardiac death, and determine the best methods for rapid and reliable assessment. ^ In conclusion, this research suggests that the volume of activity reported by US adults is not associated with low BMD at two clinically relevant sites, casts doubts on the utility of two existing cardiac screening tools, and raises concern about barriers to activity erected through ineffective screening. These findings augment existing research in this area that may inform revisions to the Physical Activity Guidelines regarding risk mitigation.^

External assessment of myocardial glucose metabolism with $\sp{18}$F-2 -deoxy-2 -fluoro-D-glucose

Despite the popularity of the positron emitting glucose analog, ($\sp{18}$F) -2-deoxy-2-fluoro-D-glucose (2FDG), for the noninvasive "metabolic imaging" of organs with positron emission tomography (PET), the physiological basis for the tracer has not been tested, and the potential of 2FDG for the rapid kinetic analysis of altered glucose metabolism in the intact heart has not been fully exploited. We, therefore, developed a quantitative method to characterize metabolic changes of myocardial glucose metabolism noninvasively and with high temporal resolution.^ The first objective of the work was to provide direct evidence that the initial steps in the metabolism of 2FDG are the same as for glucose and that 2FDG is retained by the tissue in proportion to the rate of glucose utilization. The second objective was to characterize the kinetic changes in myocardial glucose transport and phosphorylation in response to changes in work load, competing substrates, acute ischemia and reperfusion, and the addition of insulin. To assess changes in myocardial glucose metabolism isolated working rat hearts were perfused with glucose and 2FDG. Tissue uptake of 2FDG and the input function were measured on-line by external detection. The steady state rate of 2FDG phosphorylation was determined by graphical analysis of 2FDG time-activity curves.^ The rate of 2FDG uptake was linear with time and the tracer was retained in its phosphorylated form. Tissue accumulation of 2FDG decreased within seconds with a reduction in work load, in the presence of competing substrates, and during reperfusion after global ischemia. Thus, most interventions known to alter glucose metabolism induced rapid parallel changes in 2FDG uptake. By contrast, insulin caused a significant increase in 2FDG accumulation only in hearts from fasted animals when perfused at a sub-physiological work load. The mechanism for this phenomenon is not known but may be related to the existence of two different glucose transporter systems and/or glycogen metabolism in the myocardial cell.^ It is concluded that (1) 2FDG traces glucose uptake and phosphorylation in the isolated working rat heart; and (2) early and transient kinetic changes in glucose metabolism can be monitored with high temporal resolution with 2FDG and a simple positron coincidence counting system. The new method has revealed transients of myocardial glucose metabolism, which would have remained unnoticed with conventional methods. These transients are not only important for the interpretation of glucose metabolic PET scans, but also provide insights into mechanisms of glucose transport and phosphorylation in heart muscle. ^

Haemolymph inorganic ion composition, physiology and behaviour dependent on temperature and ambient magnesium concentration in early life history stages of Paralomis granulosa (Decapoda, Anomura, Lithodidae)

Marine brachyuran and anomuran crustaceans are completely absent from the extremely cold (-1.8 °C) Antarctic continental shelf, but caridean shrimps are abundant. This has at least partly been attributed to low capacities for magnesium excretion in brachyuran and anomuran lithodid crabs ([Mg2+]HL = 20-50 mmol/L) compared to caridean shrimp species ([Mg2+]HL = 5-12 mmol/L). Magnesium has an anaesthetizing effect and reduces cold tolerance and activity of adult brachyuran crabs. We investigated whether the capacity for magnesium regulation is a factor that influences temperature-dependent activity of early ontogenetic stages of the Sub-Antarctic lithodid crab Paralomis granulosa. Ion composition (Na+, Mg2+, Ca2+, Cl-, [SO4]2-) was measured in haemolymph withdrawn from larval stages, the first and second juvenile instars (crabs I and II) and adult males and females. Magnesium excretion improved during ontogeny, but haemolymph sulphate concentration was lowest in the zoeal stages. Neither haemolymph magnesium concentrations nor Ca2+:Mg2+ ratios paralleled activity levels of the life stages. Long-term (3 week) cold exposure of crab I to 1 °C caused a significant rise of haemolymph sulphate concentration and a decrease in magnesium and calcium concentrations compared to control temperature (9 °C). Spontaneous swimming activity of the zoeal stages was determined at 1, 4 and 9 °C in natural sea water (NSW, [Mg2+] = 51 mmol/L) and in sea water enriched with magnesium (NSW + Mg2+, [Mg2+] = 97 mmol/L). It declined significantly with temperature but only insignificantly with increased magnesium concentration. Spontaneous velocities were low, reflecting the demersal life style of the zoeae. Heart rate, scaphognathite beat rate and forced swimming activity (maxilliped beat rate, zoea I) or antennule beat rate (crab I) were investigated in response to acute temperature change (9, 6, 3, 1, -1 °C) in NSW or NSW + Mg2+. High magnesium concentration reduced heart rates in both stages. The temperature-frequency curve of the maxilliped beat (maximum: 9.6 beats/s at 6.6 °C in NSW) of zoea I was depressed and shifted towards warmer temperatures by 2 °C in NSW + Mg2+, but antennule beat rate of crab I was not affected. Magnesium may therefore influence cold tolerance of highly active larvae, but it remains questionable whether the slow-moving lithodid crabs with demersal larvae would benefit from an enhanced magnesium excretion in nature.

Automatic motion compensation of free breathing acquired myocardial perfusion data by using independent component analysis

Images acquired during free breathing using first-pass gadolinium-enhanced myocardial perfusion magnetic resonance imaging (MRI) exhibit a quasiperiodic motion pattern that needs to be compensated for if a further automatic analysis of the perfusion is to be executed. In this work, we present a method to compensate this movement by combining independent component analysis (ICA) and image registration: First, we use ICA and a time?frequency analysis to identify the motion and separate it from the intensity change induced by the contrast agent. Then, synthetic reference images are created by recombining all the independent components but the one related to the motion. Therefore, the resulting image series does not exhibit motion and its images have intensities similar to those of their original counterparts. Motion compensation is then achieved by using a multi-pass image registration procedure. We tested our method on 39 image series acquired from 13 patients, covering the basal, mid and apical areas of the left heart ventricle and consisting of 58 perfusion images each. We validated our method by comparing manually tracked intensity profiles of the myocardial sections to automatically generated ones before and after registration of 13 patient data sets (39 distinct slices). We compared linear, non-linear, and combined ICA based registration approaches and previously published motion compensation schemes. Considering run-time and accuracy, a two-step ICA based motion compensation scheme that first optimizes a translation and then for non-linear transformation performed best and achieves registration of the whole series in 32 ± 12 s on a recent workstation. The proposed scheme improves the Pearsons correlation coefficient between manually and automatically obtained time?intensity curves from .84 ± .19 before registration to .96 ± .06 after registration

Exome-wide analysis of rare coding variation identifies novel associations with COPD and airflow limitation in MOCS3, IFIT3 and SERPINA12

Funding: British Women’s Heart and Health Study is funded by the Department of Health grant no. 90049 and the British Heart Foundation grant no. PG/09/022. British Regional Heart Study is supported by the British Heart Foundation (grant RG/ 13/16/30528). CB (COPDBEAT) received funding from the Medical Research Council UK (grant no. G0601369), CB (COPDBEAT) and AJW (UKCOPD) were supported by the National Institute for Health Research (NIHR Leicester Biomedical Research Unit). MB (COPDBEAT) received funding from the NIHR (grant no. PDF-2013-06-052). Hertfordshire Cohort Study received support from the Medical Research Council, Arthritis Research UK, the International Osteoporosis Foundation and the British Heart Foundation; NIHR Biomedical Research Centre in Nutrition, University of Southampton; NIHR Musculoskeletal Biomedical Research Unit, University of Oxford. Generation Scotland: Scottish Family Health Study is funded by the Chief Scientist Office, Scottish Government Health Directorates, grant number CZD/16/6 and the Scottish Funding Council grant HR03006. EU COPD Gene Scan is funded by the European Union, grant no. QLG1-CT-2001-01012. English Longitudinal Study of Aging is funded by the Institute of Aging, NIH grant No. AG1764406S1. GoDARTs is funded by the Wellcome Trust grants 072960, 084726 and 104970. MDT has been supported by MRC fellowship G0902313. UK Biobank Lung Exome Variant Evaluation study was funded by a Medical Research Council strategic award to MDT, IPH, DPS and LVW (MC_PC_12010)