Nanomechanical detection of nuclear magnetic resonance using a silicon nanowire oscillator

We report the use of a silicon nanowire mechanical oscillator as a low-temperature nuclear magnetic resonance force sensor to detect the statistical polarization of 1H spins in polystyrene. Under operating conditions, the nanowire experienced negligible surface-induced dissipation and exhibited a nearly thermally-limited force noise of 1.9 aN^2/Hz in the measurement quadrature. In order to couple the 1H spins to the nanowire oscillator, we have developed a new magnetic resonance force detection protocol which utilizes a nanoscale current-carrying wire to produce large time-dependent magnetic field gradients as well as the rf magnetic field.Comment: 14 pages, 5 figure

Using art to assess environmental education outcomes

Construction of developmentally appropriate tools for assessing the environmental attitudes and awareness of young learners has proven to be challenging. Art-based assessments that encourage creativity and accommodate different modes of expression may be a particularly useful complement to conventional tools (e.g. surveys), but their efficacy and feasibility across diverse contexts has not been adequately explored. To examine the potential utility of integrating art into evaluations of environmental education outcomes, we adapted an existing drawing prompt and corresponding grading rubric to assess the environmental attitudes and awareness of children (ages 6–12) at summer camps in Athens, GA, USA (n = 285). We then compared children’s drawings with scores on a more typical survey instrument that measured similar outcomes, the Children Environmental Perception’s Scale. Results showed that a drawing prompt was a practical and unique learner-centered tool for measuring distinct components of environmental attitudes and awareness. Findings also revealed different response patterns across the two instruments, highlighting the value of using multiple approaches (e.g. art-based and survey-based) to assess cognitive and affective aspects of children’s environmental orientations

Iron overload in paediatrics undergoing cardiopulmonary bypass

AbstractPathological changes in iron status are known to occur during bypass and will be superimposed upon physiological abnormalities in iron distribution, characteristic of the neonatal period. We have sought to define the severity of iron overload in these patients. Plasma samples from 65 paediatric patients undergoing cardiopulmonary bypass (CPB) were analysed for non-haem iron, total iron binding capacity, transferrin and bleomycin-detectable iron. Patients were divided into four age groups for analysis. Within each age group, patients who were in iron overload at any time point were statistically compared to those who were not. The most significant changes in iron chemistry were seen in the plasma of neonates, with 25% in a state of plasma iron overload. 18.5% of infants and 14.3% of children at 1–5 years were also in iron overload at some time point during CPB. No children over 5 years, however, went into iron overload. Increased iron saturation of transferrin eliminates its ability to bind reactive forms of iron and to act as an antioxidant. When transferrin is fully saturated with iron, reactive forms of iron are present in the plasma which can stimulate iron-driven oxidative reactions. Our data suggest that paediatric patients are at greater risk of iron overload during CPB, and that some form of iron chelation therapy may be advantageous to decrease oxidative stress

Left ventricular dysfunction after open repair of simple congenital heart defects in infants and children: Quantitation with the use of a conductance catheter immediately after bypass

AbstractObjective: Quantification of myocardial injury after the simplest pediatric operations by load-independent indices of left ventricular function, using conductance and Mikro-Tip pressure catheters (Millar Instruments, Inc., Houston, Tex.) inserted through the left ventricular apex. Methods: Sixteen infants and children with intact ventricular septum undergoing cardiac operations had left ventricular function measured, immediately before and after bypass. Real-time pressure-volume loops were generated by conductance and Mikro-Tip pressure catheters placed in the long-axis via the left ventricular apex, and preload was varied by transient snaring of the inferior vena cava. Results: Good quality pressure-volume loops were generated in 13 patients (atrial septal defects, n = 11; double-chambered right ventricle, n = 1; supravalvular aortic stenosis, n = 1; age 0.25 to 14.4 years, weight 3.1 to 46.4 kg). Their mean bypass time was 41 ± 14 minutes and mean aortic crossclamp time 27 ± 11 minutes. End-systolic elastance decreased by 40.7% from 0.34 ± 0.17 to 0.21 ± 0.15 mm Hg-1·ml-1·kg-1 (p < 0.001). There were no significant changes in the slope of the stroke work–end-diastolic volume relationship, end-diastolic elastance, time constant of isovolumic relaxation, and normalized values of the maxima and minima of the first derivative of developed left ventricular pressure. Conclusion: Load-independent indices of left ventricular function can be derived from left ventricular pressure-volume loops generated by conductance and Mikro-Tip pressure catheters during the perioperative period in infants and children undergoing cardiac operations. Incomplete myocardial protection was demonstrated by a deterioration in systolic function after even short bypass and crossclamp times.Ignorance of the cause of postoperative myocardial dysfunction in the immature heart is compounded by the incomplete myocardial protection afforded by current cardioplegic strategies.1,5 Investigations of the mechanisms and treatment of postoperative ventricular dysfunction are hampered by use of nonspecific clinical end points as indirect estimates of ventricular function, for example, requirement for inotropic agents, duration of ventilation, intensive care unit stay, and mortality. These clinical indices are relatively insensitive to changes in ventricular function and necessitate large cohorts of patients to detect even major differences in outcome from differing myocardial protective strategies.To measure left ventricular function optimally during the perioperative period, with its dramatic changes in loading conditions, necessitates the use of load-independent indices of systolic and diastolic function. In infants and children with an intact ventricular septum undergoing cardiac operations (mainly atrial septal defect closure), we report the changes in left ventricular function assessed from the pressure-volume plane with the use of a conductance catheter and Mikro-Tip pressure catheter (Millar Instruments, Inc., Houston, Tex). In animal and human studies the conductance catheter is placed in the long axis of the left ventricle, most commonly through the aortic valve, with the use of retrograde arterial cannulation or aortotomy.6-11 This is clearly impractical in children undergoing bypass procedures, and in this study we report the first clinical use of custom-built miniature catheters placed in the same long axis, but via the left ventricular apex

Receptor guanylyl cyclase (RGC) family (version 2020.3) in the IUPHAR/BPS Guide to Pharmacology Database

The mammalian genome encodes seven guanylyl cyclases, GC-A to GC-G, that are homodimeric transmembrane receptors activated by a diverse range of endogenous ligands. These enzymes convert guanosine-5'-triphosphate to the intracellular second messenger cyclic guanosine-3',5'-monophosphate (cyclic GMP). GC-A, GC-B and GC-C are expressed predominantly in the cardiovascular system, skeletal system and intestinal epithelium, respectively. GC-D and GC-G are found in the olfactory neuropepithelium and Grueneberg ganglion of rodents, respectively. GC-E and GC-F are expressed in retinal photoreceptors

Receptor guanylyl cyclase (RGC) family in GtoPdb v.2023.1

The mammalian genome encodes seven guanylyl cyclases, GC-A to GC-G, that are homodimeric transmembrane receptors activated by a diverse range of endogenous ligands. These enzymes convert guanosine-5'-triphosphate to the intracellular second messenger cyclic guanosine-3',5'-monophosphate (cyclic GMP). GC-A, GC-B and GC-C are expressed predominantly in the cardiovascular system, skeletal system and intestinal epithelium, respectively. GC-D and GC-G are found in the olfactory neuropepithelium and Grueneberg ganglion of rodents, respectively. GC-E and GC-F are expressed in retinal photoreceptors