Kaehler Manifolds of Quasi-Constant Holomorphic Sectional Curvatures

The Kaehler manifolds of quasi-constant holomorphic sectional curvatures are introduced as Kaehler manifolds with complex distribution of codimension two, whose holomorphic sectional curvature only depends on the corresponding point and the geometric angle, associated with the section. A curvature identity characterizing such manifolds is found. The biconformal group of transformations whose elements transform Kaehler metrics into Kaehler ones is introduced and biconformal tensor invariants are obtained. This makes it possible to classify the manifolds under consideration locally. The class of locally biconformal flat Kaehler metrics is shown to be exactly the class of Kaehler metrics whose potential function is only a function of the distance from the origin in complex Euclidean space. Finally we show that any rotational even dimensional hypersurface carries locally a natural Kaehler structure, which is of quasi-constant holomorphic sectional curvatures.Comment: 36 page

Roles of dimerization domain residues in binding and catalysis by aminoacylase-1

The aminoacylase-1/metallopeptidase 20 (Acy1/M20) family is the largest metallopeptidase family. Several crystal structures feature a metal-binding and a dimerization-mediating domain, both arranged in an extended open conformation. We have recently shown [Lindner et al. (2003) J. Biol. Chem. 278, 44496-44504] that in human Acy1 the invariant residues Glu147 and His206 from the metal-binding and the dimerization domain, respectively, are recruited to the active site from opposite dimer subunits. We hypothesized that, to facilitate this, formation of the binary complex is associated with domain closure, which would also position additional residues in the functional active site of Acy1. These would include two partially conserved dimerization domain residues: an asparagine (Asn263) and an arginine (Arg276) from the same subunit as His206 and Glu147, respectively. In this paper, we investigate the significance of the three dimerization domain residues of human Acy1 His206, Asn263, and Arg276 and, additionally, the nearby Asp274 for catalysis using site-directed mutagenesis. Enzyme complementation assays confirm the putative subunit allocations of these residues, and steady-state kinetics support roles for all of them in catalysis but only involve the Arg276 in substrate-binding. The results are consistent with a model of the closed conformation for the structure of the related enzyme carboxypeptidase G2. This study demonstrates experimentally for the first time for a member of the Acy1/M20 family that several residues outside of the metal-binding domain are involved in binding and catalysisNRC publication: Ye

100 laser beam array phase-locked in a neural network loop

International audienc

Nephroprotective Effects of Mycophenolate Mofetil and Glibenclamide on Streptozotocin-induced Diabetic Renal Injury in Rats: An Experimental Study

Diabetic renal injury is a microvascular complication associated with inflammation and oxidative stress, culminating in renal dysfunction. Conventionally, it is treated with hypoglycemic agents to address metabolic perturbations. However, the way to mitigate immunological, inflammation, and oxidative stress have seldom been studied. Hence, in the present study, the nephroprotective role of immunosuppressive and anti-inflammatory drugs, mycophenolate mofetil (MMF) in combination with the oral hypoglycemic agent glibenclamide, on streptozotocin (STZ)- induced diabetic renal damage was studied. Bodyweight, fasting blood glucose, and glycosylated hemoglobin levels were altered in the diabetic rats. Furthermore, renal injury was indicated by abnormal levels of urinary protein and creatinine and serum markers of renal function in diabetic rats. Hyperglycemia-induced oxidative stress and inflammation were also observed in the diabetic rats. The combination of MMF and glibenclamide treatment significantly attenuated the abnormal effects of hyperglycemia, oxidative stress, and inflammation-induced renal injury in diabetic rats. Histopathological studies confirmed the nephroprotective role of MMF and glibenclamide by reversing renal injury in diabetic rats. The present study suggests that MMF and glibenclamide have a protective role in STZ-induced diabetic renal damage

Small footprint phase locking system for large tiled aperture laser array

International audienceA phase sensing system fitted to the control of coherent laser beam array of large cross section is experimented. It is based on the use of a fiber bundle that collects a weak part of the synthetic wavefront, that scales it down (1/40) and that reshapes it in a more compact arrangement (2D to 1D array). Then, the reconfigured beam array can be analyzed by a small footprint system making the large laser beam array easier to phase-lock. The discrete laser array wavefront transmitted by the meter long fiber bundle was stabilized thanks to a multiple arm servo loop. Laser array phase locking was further ensured by random scattering through a diffuser, associated to an alternating projection algorithm. Six fiber laser beams constituting a 110 mm diameter synthetic aperture, were phase-locked with lambda/16 accuracy