942-42 Is Mitral Valve Prolapse with Significant Mitral Regurgitation a Different Condition from Uncomplicated Mitral Prolapse? Results of Family Studies

Mild instances of mitral valve prolapse (MVP) have been suggested to represent variants of normal, whereas individuals with complicated forms of MVP have a distinct medical condition. This hypothesis would predict different phenotypic features and patterns of inheritance in relatives of index cases with complicated or uncomplicated MVP. Accordingly, we performed clinical and echocardiographic assessment of 16 MVP patients with and 76 without moderate to severe mitral regurgitation (MR+and MR– probands) and 60 and 256, respectively, first-degree relatives (MR+ and MR– relatives). MR+ probands were older (p=0.01), more likely to be male (p=0.002), were more overweight (p=0.004) and had higher systolic blood pressures (p=0.05) and larger aortic roots (p=0.034) after the effects of age and body size were taken into account. MR+ and MR– relatives had similar prevalences (27 and 32%) and age distribution of MVP, but affected MR+ relatives were younger (expected because more children and fewer parents of MR+ probands could be evaluated). and more likely to be male. MR+ and MR- relatives were virtually identical in regard to body habitus, blood pressure, the prevalence of auscultatory findings, thoracic bony abnormalities and palpitations and all echo measurements including anterior mitral leaflet thickness. Four instances of significant MR and two MVP-related complications (infective endocarditis and transient ischemic attack) occurred in the 82 relatives of MR– probands as opposed to none among relatives of MR+ probands. In 20 families, one proband or relative with MVP had severe MR and at least one other with MVP (presumably due to the same gene) was free of MR or complications. Thus, MVP with severe MR does not represent a heritable phenotype and commonly coexists with mild forms of MVP in the same family, making their classification as separate conditions illogical and potentially misleading

763-1 Assessment of Left Ventricular Function by Circumferential Stress-Midwall Shortening Relations in Dilated Cardiomyopathy

Echocardiographic stress endocardial shortening relations provide estimates of LV contractility that do not uniformly detect myocardial dysfunction in dilated cardiomyopathy (DCM). Recently it has become apparent that midwall (mid) fractional shortening and circumferential (c) end-systolic stress (ESS) provide the most appropriate paired afterload and function measures. Both meridional (m) and cESS were related to both endocardial (e) FS and midFS in 42 patients with DCM (98% dead during follow-up; eFS =4% in the survivor) and in 140 normals. Eight patients (19%) fell into the 95% confidence interval of the normal relation of eFS to mESS (top panel), 14% had apparently normal midFS-mESS relations but midFS was depressed in relation to cESS in 100% of patients (lower panel). Thus, (1) use of cESS-shortening relations improves the ability to identify patients with depressed LV function; (2) use of midFS or eFS are equivalent in DCM with LV dilatation and wall thinning

Functional immunoglobulin transgenes guide ordered B-cell differentiation in Rag-1-deficient mice

We have examined the regulatory role of the individual components of the immunoglobulin antigen receptor in B-cell development by transgenic complementation of Rag-1 deficient (Rag-1⁻) mice. Complementation with a membrane µ heavy chain (µHC) gene allows progression of developmentally arrested Rag-1⁻ pro-B-cells to the small pre-B cell stage, whereas the introduction of independently integrated µHC and κ light chain (κLC) transgenes promotes the appearance of peripheral lymphocytes which, however, remain unresponsive to external stimuli. Complete reconstitution of the B-cell lineage and the emergence of functionally nature Rag-1⁻ peripheral B cells is achieved by the introduction of cointegrated heavy and light chain transgenes encoding an anti-H-2^k antibody. This experimental system demonstrates the competence of the µHC and κLC to direct and regulate the sequential stages of B-cell differentiation, defines the time at which negative selection of self-reactive B cells occurs, and shows that elimination of these cells occurs equally well in the absence of Rag-1 as in its presence. These data also support the hypothesis that Rag-1 directly participates in the V(D)J recombination process

Cytochrome P4504A inhibitors attenuate the exaggerated natriuretic response to volume expansion in thyroidectomized rats

Thyroidectomy augments the natriuretic response to volume expansion; however, the mechanism remains unknown. This study assessed the role of 20-hydroxyeicosatetraenoic acid (20-HETE) in the natriuretic response to an acute volume expansion in hypothyroid rats. Urine flow (1.9-fold), sodium excretion (2.4-fold), fractional sodium excretion (3.8-fold), and distal delivery of sodium (4.1-fold) increased to a greater extent in thyroidectomized rats (TX) than in sham-operated controls (SHAM) following i.v. infusion of isotonic saline (5% body weight) over 60 min. This was associated with inhibition of both proximal and distal tubular reabsorption of sodium. Administration of two mechanistic and chemical dissimilar inhibitors of the synthesis of 20- HETE, 1-aminobenzotriazole (ABT), and N-hydroxy-N?-(-4-butyl-2-methylphenyl) formamidine (HET0016) decreased the natriuretic response in TX rats. Glomerular filtration rate was lower in TX than in SHAM rats and was not altered by the CYP4A inhibitors. The expression, intrarenal distribution, and the formation of 20-HETE and expoxygenase metabolites of arachidonic acid were similar in the cortex and medulla of SHAM and TX rats. These results suggest that CYP4A-derived metabolites of arachidonic acid play an important role in the enhanced natriuretic response to volume expansion in hypothyroid rats even though TX did not alter the expression or activity of these enzymes.Fil: Colombero Rivas, Cecilia Edith. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones Endocrinológicas; ArgentinaFil: Venara, Marcela Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones Endocrinológicas; ArgentinaFil: Gonzalez, Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones Endocrinológicas; ArgentinaFil: Roman, Richard J.. University Of Mississippi; Estados UnidosFil: Nowicki, Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Centro de Investigaciones Endocrinológicas; Argentin

The entropic basis of collective behaviour

We identify a unique viewpoint on the collective behaviour of intelligent agents. We first develop a highly general abstract model for the possible future lives these agents may encounter as a result of their decisions. In the context of these possibilities, we show that the causal entropic principle, whereby agents follow behavioural rules that maximize their entropy over all paths through the future, predicts many of the observed features of social interactions among both human and animal groups. Our results indicate that agents are often able to maximize their future path entropy by remaining cohesive as a group and that this cohesion leads to collectively intelligent outcomes that depend strongly on the distribution of the number of possible future paths. We derive social interaction rules that are consistent with maximum entropy group behaviour for both discrete and continuous decision spaces. Our analysis further predicts that social interactions are likely to be fundamentally based on Weber's law of response to proportional stimuli, supporting many studies that find a neurological basis for this stimulus-response mechanism and providing a novel basis for the common assumption of linearly additive 'social forces' in simulation studies of collective behaviour

Optical second harmonic generation in encapsulated single-layer InSe

We report the observation of optical second harmonic generation (SHG) in single-layer indium selenide (InSe). We measure a second harmonic signal of $>10^3$ $\textrm{cts/s}$ under nonresonant excitation using a home-built confocal microscope and a standard pulsed pico-second laser. We demonstrate that polarization-resolved SHG serves as a fast, non-invasive tool to determine the crystal axes in single-layer InSe and to relate the sharp edges of the flake to the armchair and zigzag edges of the crystal structure. Our experiment determines these angles to an accuracy better than $\pm$ $0.2^{\circ}$. Treating the two-dimensional material as a nonlinear polarizable sheet, we determine a second-order nonlinear sheet polarizability $| \chi_{\textrm{sheet}}^{(2)}|=(17.9 \pm 11.0)\times 10^{-20}$ $\textrm{m}^2 \textrm{V}^{-1}$ for single-layer InSe, corresponding to an effective nonlinear susceptibility value of $| \chi_\textrm{eff}^{(2)}| \approx (223 \pm 138) \times 10^{-12}$ $\textrm{m} \textrm{V}^{-1}$ accounting for the sheet thickness ($\textrm{d} \approx 0.8$ $\textrm{nm}$). We demonstrate that the SHG technique can also be applied to encapsulated samples to probe their crystal orientations. The method is therefore suitable for creating high quality van der Waals heterostructures with control over the crystal directions

Test of OPE and OGE through mixing angles of negative parity N* resonances in electromagnetic transitions

In this report, by using the mixing angles of one-gluon-exchange model(OGE) and one-pion-exchange model(OPE), and by using the electromagnetic Hamiltonian of Close and Li, we calculate the amplitudes of L=1 N* resonances for photoproduction and electroproduction. The results are compared to experimental data. It's found that the data support OGE, not OPE.Comment: 5 pages, Latex, 1 figure, accepted by Phys.Rev.

International Space Station Active Thermal Control Sub-System On-Orbit Pump Performance and Reliability Using Liquid Ammonia as a Coolant

The International Space Station (ISS) contains two Active Thermal Control Sub-systems (ATCS) that function by using a liquid ammonia cooling system collecting waste heat and rejecting it using radiators. These subsystems consist of a number of heat exchangers, cold plates, radiators, the Pump and Flow Control Subassembly (PFCS), and the Pump Module (PM), all of which are Orbital Replaceable Units (ORU's). The PFCS provides the motive force to circulate the ammonia coolant in the Photovoltaic Thermal Control Subsystem (PVTCS) and has been in operation since December, 2000. The Pump Module (PM) circulates liquid ammonia coolant within the External Active Thermal Control Subsystem (EATCS) cooling the ISS internal coolant (water) loops collecting waste heat and rejecting it through the ISS radiators. These PM loops have been in operation since December, 2006. This paper will discuss the original reliability analysis approach of the PFCS and Pump Module, comparing them against the current operational performance data for the ISS External Thermal Control Loops