The yoga of commutators

In the present paper we discuss some recent versions of localisation methods for calculations in the groups of points of algebraic-like and classical-like groups. Namely, we describe relative localisation, universal localisation, and enhanced versions of localisation-completion. Apart from the general strategic description of these methods, we state some typical technical results of the conjugation calculus and the commutator calculus. Also, we state several recent results obtained therewith, such as relative standard commutator formulae, bounded width of commutators, with respect to the elementary generators, and nilpotent filtrations of congruence subgroups. Overall, this shows that localisation methods can be much more efficient, than expected

Stentless pyeloplasty for ureteropelvic junction obstruction in children

Introduction Stenting after pyeloplasty is an established practice and helps in  ensuring a patent anastomosis until healing has completed. Stents, however, may cause complications such as infection and displacement and increase the cost of management; therefore, stentless pyeloplasty is now considered as feasible  alternative.Patients and methods From August 2008 to October 2010, we retrospectively analyzed the results of stentless surgery in patients with ureteropelvic junction  (UPJ) obstruction. In all, 42 patients with UPJ obstruction were managed. Nine patients who were treated conservatively, one who underwent nephrectomy, and one pyelostomy for pyonephrosis in solitary kidney were excluded. Age range at surgery was 14 days–12 years with a mean age of 12.7 months.Results There were 23 male patients and eight female patients with a male-to-female ratio of 3 : 1. Fourteen patients had left, 12 right, and five had bilateral UPJ obstruction. A total of 34 pyeloplasties were performed in 31 patients. Of the five patients with bilateral UPJ obstruction, three underwent bilateral pyeloplasty and remaining two underwent unilateral pyeloplasty with conservative management on the opposite sides. Two patients underwent laparoscopic pyeloplasties and32 pyeloplasties by open technique. Double J stent was placed at initial surgery in three patients and 31 stentless pyeloplasties were performed. The mean operative time was 75 min. The mean perinephric drain removal time was 2 days. None of the patients had persistent urinary leak. The mean hospital stay was 3.2 days. Reduction in anteroposterior diameter was noticed in 91% cases on 12 weeks  follow-up scan. Complications included persistent or increase in hydronephrosis in three (9%) patients. In all the three patients, cystoscopic stenting was attempted. In two patients, size 4 Fr double J stent was passed easily into the renal pelvis. Onepatient improved, whereas other still has a dilated pelvis with static anteroposterior diameter after removal of stent at 6 weeks; patient is kept on close surveillance on regular ultrasonography. Re-exploration was performed in one patient, which showed kinking at the anastomosis site. Pyeloplasty was revised and patient improved. Other complications included lumbar hernia in one patient, which improved at 6-month follow-up, and stitch granuloma in one patient, which improved after removal of residual stitch.Conclusion Stentless surgery for UPJ obstruction is a safe and feasible technique; it reduces the cost of surgery and avoids multiple procedures. Keywords: management, pyeloplasty, stentless, ureteropelvic junction obstruction

Crystal structure of an inulosucrase from Halalkalicoccus jeotgali B3T-a halophilic archaeal strain

Several archaea harbour genes that code for fructosyltransferase (FTF) enzymes. These enzymes have not been characterized yet at structure-function level, but are of extreme interest in view of their potential role in the synthesis of novel compounds for food, nutrition and pharmaceutical applications. In this study, 3D structure of an inulin-type fructan producing enzyme, inulosucrase (InuHj), from the archaeon Halalkalicoccus jeotgali was resolved in its apo form as well as with bound substrate (sucrose) molecule and first transglycosylation product (1-kestose). This is the first crystal structure of an FTF from halophilic archaea. Its overall five-bladed β-propeller fold is conserved with previously reported FTFs, but also shows some unique features. The InuHj structure is closer to those of Gram-negative bacteria, with exceptions such as residue E266, which is conserved in FTFs of Gram-positive bacteria and has possible role in fructan polymer synthesis in these bacteria as compared to fructooligosaccharide (FOS) production by FTFs of Gram-negative bacteria. Highly negative electrostatic surface potential of InuHj, due to a large amount of acidic residues, likely contributes to its halophilicity. The complex of InuHj with 1-kestose indicates that the residues D287 in the 4B-4C loop, Y330 in 4D-5A and D361 in the unique α2 helix may interact with longer FOSs and facilitate the binding of longer FOS chains during synthesis. The outcome of this work will provide targets for future structure-function studies of FTF enzymes, particularly those from archaea

Automorphisms and isomorphisms of Chevalley groups and algebras

An adjoint Chevalley group of rank at least 2 over a rational algebra (or a similar ring), its elementary subgroup, and the corresponding Lie ring have the same automorphism group. These automorphisms are explicitly described.Comment: 8 pages. A Russian version of this paper is at http://mech.math.msu.su/department/algebra/staff/klyachko/papers.htm . V4: minor changes in Introduction and Reference