The biosynthesis of y-glutamyltransferase in cortical slices has been examined by Nash & Tate.The finding that the enzyme arises in LLC-PK1 cells during differentiation in vitro suggests that the cell line can be used to study the biogenesis order Motesanib selleckchem of this membrane protein under controlled conditions.It also provides a cellular model in which to study the importance of y-glutamyltransferase in the catabolism of intra- or extra-cellular glutathione.The longitudinal relaxation rate of HP gases induced by diffusion through transverse magnetic field gradients,,can be expressed as D is the diffusion constant of HP gas,?0 is the nuclear resonance frequency at the static magnetic field strength,B0,and the relevant correlation time,?c is approximately the mean time between HP gas collisions.As first explained by Gamblin and Carver ,it is the diffusion of gas atoms through the gradients of the transverse magnetic fields |??Bx|2 and |??By|2 that causes relaxation.In the atoms? reference frame,their random Brownian motion causes the gradients to appear as randomly fluctuating transverse magnetic fields,which can induce spin flips just as a transverse radio frequency pulse would.For common situations Eq.
is amenable to several simplifications.Firstly,the last term approaches unity under low-field conditions,an assumption which is valid for 3He under our experimental conditions ,given correlation times of 0.29 ns at 300 K for 1 atm.Secondly,since Bortezomib typical superconducting MR magnets possess cylindrical symmetry,i.e.an azimuthally symmetric current distribution,the polar component of the field B? is explicitly zero,leaving the only nontrivial components Bz,where ? lies along the central axis of the field,and B?,where ?? is the radial component,which is perpendicular to the central axis.Moreover,the azimuthally symmetric current distribution assures that Bz and B? are functions only of ? and z and do not depend on ?.For this type of symmetry,as we show in Appendix 1,it is possible to transform |??Bx|2 + |??By|2 in Eq.into cylindrical form with |??B?|2 + B?2/?2,and Eq.can be rewritten as Hyperpolarized 3He was prepared for relaxation measurements by spin-exchange optical pumping.3He was polarized overnight to 30? 40% using a prototype commercial polarizer.Prior to relaxation experiments,the spin-exchange optical cell was cooled to room temperature,and ~100 ml of HP 3He was dispensed into 8?10 cm2 Tedlar bags at atmospheric pressure.3.2 Magnetic Field Mapping Magnetic field mapping and relaxation measurements were made for a 2-T horizontal bore magnet with a 30-cm bore.Its magnetic field was measured along the central axis and 11.4-cm off-axis using a gauss-meter.