Development of a steam powered sports car

Thesis (B.S.) Massachusetts Institute of Technology. Dept. of Mechanical Engineering, 1957.MIT copy bound with: Test and modification of a density compensated orifice flowmeter / Allan Eckhaus. 1957.Bibliography: leaf [60].by William B. Fleischer and Sidney Zafran.B.S

Three-Dimensional Visualization of FKBP12.6 Binding to an Open Conformation of Cardiac Ryanodine Receptor

AbstractThe cardiac isoform of the ryanodine receptor (RyR2) from dog binds predominantly a 12.6-kDa isoform of the FK506-binding protein (FKBP12.6), whereas RyR2 from other species binds both FKBP12.6 and the closely related isoform FKBP12. The role played by FKBP12.6 in modulating calcium release by RyR2 is unclear at present. We have used cryoelectron microscopy and three-dimensional (3D) reconstruction techniques to determine the binding position of FKBP12.6 on the surface of canine RyR2. Buffer conditions that should favor the “open” state of RyR2 were used. Quantitative comparison of 3D reconstructions of RyR2 in the presence and absence of FKBP12.6 reveals that FKBP12.6 binds along the sides of the square-shaped cytoplasmic region of the receptor, adjacent to domain 9, which forms part of the four clamp (corner-forming) structures. The location of the FKBP12.6 binding site on “open” RyR2 appears similar, but slightly displaced (by 1–2nm) from that found previously for FKBP12 binding to the skeletal muscle ryanodine receptor that was in the buffer that favors the “closed” state. The conformation of RyR2 containing bound FKBP12.6 differs considerably from that depleted of FKBP12.6, particularly in the transmembrane region and in the clamp structures. The x-ray structure of FKBP12.6 was docked into the region of the 3D reconstruction that is attributable to bound FKBP12.6, to show the relative orientations of amino acid residues (Gln-31, Asn-32, Phe-59) that have been implicated as being critical in interactions with RyR2. A thorough understanding of the structural basis of RyR2-FKBP12.6 interaction should aid in understanding the roles that have been proposed for FKBP12.6 in heart failure and in certain forms of sudden cardiac death

CGP-37157 Inhibits the Sarcoplasmic Reticulum Ca 2ϩ ATPase and Activates Ryanodine Receptor Channels in Striated Muscle

ABSTRACT 7-Chloro-5-(2-chlorophenyl)-1,5-dihydro-4,1-benzothiazepin-2(3H)-one ], a benzothiazepine derivative of clonazepam, is commonly used as a blocker of the mitochondrial Na ϩ /Ca 2ϩ exchanger. However, evidence suggests that CGP could also affect other targets, such as L-type Ca 2ϩ channels and plasmalemma Na ϩ /Ca 2ϩ exchanger. Here, we tested the possibility of a direct modulation of ryanodine receptor channels (RyRs) and/or sarco/endoplasmic reticulum Ca 2ϩ -stimulated ATPase (SERCA) by CGP. In the presence of ruthenium red (inhibitor of RyRs), CGP decreased SERCA-mediated Ca 2ϩ uptake of cardiac and skeletal sarcoplasmic reticulum (SR) microsomes (IC 50 values of 6.6 and 9.9 M, respectively). The CGP effects on SERCA activity correlated with a decreased V max of ATPase activity of SERCA-enriched skeletal SR fractions. CGP (Ն5 M) also increased RyR-mediated Ca 2ϩ leak from skeletal SR microsomes. Planar bilayer studies confirmed that both cardiac and skeletal RyRs are directly activated by CGP (EC 50 values of 9.4 and 12.0 M, respectively). In summary, we found that CGP inhibits SERCA and activates RyR channels. Hence, the action of CGP on cellular Ca 2ϩ homeostasis reported in the literature of cardiac, skeletal muscle, and other nonmuscle systems requires further analysis to take into account the contribution of all CGP-sensitive Ca 2ϩ transporters