Hyperbolic unit groups and quaternion algebras

We classify the quadratic extensions K = Q[root d] and the finite groups G for which the group ring o(K)[G] of G over the ring o(K) of integers of K has the property that the group U(1)(o(K)[G]) of units of augmentation 1 is hyperbolic. We also construct units in the Z-order H(o(K)) of the quaternion algebra H(K) = (-1, -1/K), when it is a division algebra.

Lie properties of crossed products

Let F-sigma(lambda)vertical bar G vertical bar be a crossed product of a group G and the field F. We study the Lie properties of F-sigma(lambda)vertical bar G vertical bar in order to obtain a characterization of those crossed products which are upper (lower) Lie nilpotent and Lie (n, m)-Engel. (C) 2008 Elsevier Inc. All rights reserved.

Hyperbolicity of semigroup algebras

Let A be a finite-dimensional Q-algebra and Gamma subset of A a Z-order. We classify those A with the property that Z(2) negated right arrow U(Gamma) and refer to this as the hyperbolic property. We apply this in case A = K S is a semigroup algebra, with K = Q or K = Q(root-d). A complete classification is given when KS is semi-simple and also when S is a non-semi-simple semigroup. (c) 2008 Elsevier Inc. All rights reserved.

Simple components of the center of FG/J(FG)

Let G be a finite group, F a field, FG the group ring of G over F, and J(FG) the Jacobson radical of FG. Using a result of Berman and Witt, we give a method to determine the structure of the center of FG/J(FG), provided that F satisfies a field theoretical condition.

Bicyclic units, Bass cyclic units and free groups

Let G be a finite group and ZG its integral group ring. We show that if alpha is a nontrivial bicyclic unit of ZG, then there are bicyclic units beta and gamma of different types, such that and are non-abelian free groups. In the case when G is non-abelian of order coprime to 6 we prove the existence of a bicyclic unit u and a Bass cyclic unit v in ZG, such that < u(m), v > is a free non-abelian group for all sufficiently large positive integers m.

HYPERBOLICITY OF SEMIGROUP ALGEBRAS II

In 1996, Jespers and Wang classified finite semigroups whose integral semigroup ring has finitely many units. In a recent paper, Iwaki-Juriaans-Souza Filho continued this line of research by partially classifying the finite semigroups whose rational semigroup algebra contains a Z-order with hyperbolic unit group. In this paper, we complete this classification and give an easy proof that deals with all finite semigroups.

GLOBALIZATION OF TWISTED PARTIAL ACTIONS

Let A be a unital ring which is a product of possibly infinitely many indecomposable rings. We establish a criteria for the existence of a globalization for a given twisted partial action of a group on A. If the globalization exists, it is unique up to a certain equivalence relation and, moreover, the crossed product corresponding to the twisted partial action is Morita equivalent to that corresponding to its globalization. For arbitrary unital rings the globalization problem is reduced to an extendibility property of the multipliers involved in the twisted partial action.

Crossed products by twisted partial actions and graded algebras

For a twisted partial action e of a group G on an (associative non-necessarily unital) algebra A over a commutative unital ring k, the crossed product A x(Theta) G is proved to be associative. Given a G-graded k-algebra B = circle plus(g is an element of G) B-g with the mild restriction of homogeneous non-degeneracy, a criteria is established for B to be isomorphic to the crossed product B-1 x(Theta) G for some twisted partial action of G on B-1. The equality BgBg-1 B-g = B-g (for all g is an element of G) is one of the ingredients of the criteria, and if it holds and, moreover, B has enough local units, then it is shown that B is stably isomorphic to a crossed product by a twisted partial action of G. (c) 2008 Elsevier Inc. All rights reserved.

Retention force of T-bar clasps for titanium and cobalt-chromium removable partial dentures

The objective of this study was to evaluate the retention force of T-bar clasps made from commercially pure titanium (CP Ti) and cobalt-chromium (Co-Cr) alloy by the insertion/removal test simulating 5 years use. Thirty-six frameworks were cast from CP Ti (n=18) and Co-Cr alloy (n=18) with identical prefabricated patterns on refractory casts from a distal extension mandibular hemi-arch segment. The castings were made on a vacuum-pressure machine, under vacuum and argon atmosphere. Each group was subdivided in three, corresponding to 0.25 mm, 0.50 mm and 0.75 mm undercuts, respectively. No polishing procedures were performed to ensure uniformity. The specimens were subjected to an insertion/removal test and data was analyzed statistically to compare CP Ti and Co-Cr alloy in the same undercut (Student's t-test for independent samples) and each material in different undercuts (one-way ANOVA) (p=0.05). Comparisons between materials revealed significant differences (p=0.017) only for the 0.50-mm undercut. No significant differences (p>0.05) were found when comparing the same material for the undercuts. It may be concluded that for different undercuts, both Co-Cr alloy and CP Ti had no significant differences for T-bar clasps; CP Ti showed the lowest retention force values when compared to Co-Cr alloy in each undercut, but with significant difference only for the 0.50-mm undercut; and both materials maintained the retentive capacity during the simulation test.

Comparative Study of the Changes in Partial Pressure of Plasma Carbon Dioxide During Carbon Dioxide Insufflation into the Intraperitoneal and Preperitoneal Spaces

Background: We aimed to compare plasma concentrations of carbon dioxide (CO(2)) in dogs that underwent intra- and preperitoneal CO(2) insufflation. Materials and Methods: Thirty dogs were studied. Ten formed a control group, 10 underwent intraperitoneal CO(2) insufflation, and 10 underwent preperitoneal CO(2) insufflation. General anesthesia with controlled ventilation was standardized for all dogs. After stabilizing the anesthesia, blood samples were collected at predetermined times and were sent for immediate gasometric analysis. Analysis of variance was used for comparing variables. Results: The plasma CO(2) concentration in the intraperitoneal insufflation group increased significantly more than in the preperitoneal insufflation group and was significantly greater than in the control group (P < 0.05). The pH values in the intraperitoneal group were lower than in the preperitoneal group (P < 0.05). Conclusion: The data from this study suggest that a greater plasma concentration of CO(2) is achieved by insufflation at constant pressure into the intraperitoneal space than into the preperitoneal space.

Partial lesions of the intratemporal segment of the facial nerve: Graft versus partial reconstruction

Objectives: In cases of partial lesions of the intratemporal segment of the facial nerve, should the surgeon perform an intraoperative partial reconstruction, or partially remove the injured segment and place a graft? We present results from partial lesion reconstruction on the intratemporal segment of the facial nerve. Methods: A retrospective study on 42 patients who presented partial lesions on the intratemporal segment of the facial nerve was performed between 1988 and 2005. The patients were divided into 3 groups based on the procedure used: interposition of the partial graft on the injured area of the nerve (group 1; 12 patients); keeping the preserved part and performing tubulization (group 2; 8 patients); and dividing the parts of the injured nerve (proximal and distal) and placing a total graft of the sural nerve (group 3; 22 patients). Results: Fracture of the temporal bone was the most frequent cause of the lesion in all groups, followed by iatrogenic causes (p < 0.005). Those who obtained results lower than or equal to III on the House-Brackmann scale were 1 (8.3%) of the patients in group 1, none (0.0%) of the patients in group 2, and 15 (68.2%) of the patients in group 3 (p < 0.001). Conclusions: The best surgical technique for therapy of a partial lesion of the facial nerve is still questionable. Among these 42 patients, the best results were those from the total graft of the facial nerve.

Prednisone monotherapy induced remission in a group of patients with membranous lupus nephritis

The treatment of membranous lupus nephritis (MLN) is still controversial in the literature. We conducted a retrospective analysis of patients in two medical centers of Sao Paulo-Brazil in order to evaluate the clinical response in patients submitted to either a regimen with prednisone alone or to a double immunosuppressive regimen (prednisone plus cyclophosphamide or prednisone plus azathioprine). Methods: MLN female patients were enrolled in this retrospective study conducted from February 1999 to June 2007. Data were collected from the patients` medical charts. Race distribution was similar in both groups: Caucasian (72.3%) and Afro-Latin-American (27.7%). The prednisone regimen consisted of 1 mg/kg/day for 8 weeks and tapering until 0.1 mg/kg/day (n = 29). The double immunosuppressive treatment consisted of the same doses of prednisone plus monthly intravenous cyclophosphamide or azathioprine for 6 months (n = 24). Criteria for remission (complete and partial) and renal function loss as well as flare criteria followed those used in the literature. Results: There was no difference between the prednisone group and the double immunosuppressive group regarding age (33.2 +/- 9.4 vs. 29.1 +/- 9.1 y), estimated GFR (76.5 +/- 26.6 vs. 74.1 +/- 39.6 ml/min/1.73 m(2)), serum albumin (2.8 +/- 0.7 vs. 2.6 +/- 0.3 g/dl), positive ANA (87.5 vs. 90.0%), positive anti-dsDNA (47.6 vs. 44.0%), renal SLEDAI indices (6.6 +/- 2.6 vs. 7.0 +/- 3.1), follow-up time (71 +/- 46 vs. 62 +/- 45 months), as well as proteinuria (3.1 +/- 1.9 vs. 4.8 +/- 2.4 g/day) and number of non-nephrotic patients (6 in the prednisone group vs. 3 in the double immunosuppressive group). The prednisone group presented higher C3 values (85.2 +/- 31.5 vs. 62.3 +/- 41.6 U/ml, p = 0.04). Clinical and laboratory characteristics at 6 months and at last follow-up did not reveal any differences between treatment regimens. Renal survival after an 8-year follow-up did not differ in both groups (prednisone group 86.2% vs. double immunosuppressive group 75%), and patients in both groups showed a high rate of renal flares (prednisone group 51.7% vs. double immunosuppressive group 62.5%). Univariate analysis showed that only patient age predicted flares (r = -0.048, p = 0.04). Borderline significance was obtained for proteinuria analysis (p = 0.07). Adverse effects did not differ between the groups. Conclusions: A regimen of corticosteroids in MLN induced a high remission rate after 6 months. Both treatment regimens showed a high flare rate and age was the only predictive parameter (r = -0.048, p = 0.04). Renal survival after 8 years did not differ between the groups.

Effects of Partial Liver Ischemia Followed by Global Liver Reperfusion on the Remote Tissue Expression of Nitric Oxide Synthase: Lungs and Kidneys

Hepatic ischemia followed by reperfusion (IR) results in mild to severe remote organ injury. Oxidative stress and nitric oxide (NO) seem to be involved in the IR injury. Our aim was to investigate the effects of liver I/R on hepatic function and lipid peroxidation, leukocyte infiltration and NO synthase (NOS) immunostaining in the lung and the kidney. We randomized 24 male Wistar rats into 3 groups: 1) control; 2) 60 minutes of partial (70%) liver 1 and 2 hours of global liver R; and 3) 60 minutes of partial (70%) liver I and 6 hours of global liver R. Groups 2 and 3 showed significant increases in plasma alanine and aspartate aminotransferase levels and in tissue malondialdehyde and myeloperoxidase contents. In the kidney, positive endothelial NOS (eNOS) staining was significantly decreased in group 3 compared with group 1. However, staining for inducible NOS (iNOS) and neuronal NOS (nNOS) did not differ among the groups. In the lung, the staining for eNOS and iNOS did not show significant differences among the groups; no positive nNOS staining was observed in any group. These results suggested that partial liver I followed by global liver R induced liver, kidney, and lung injuries characterized by neutrophil sequestration and increased oxidative stress. In addition, we supposed that the reduced NO formation via eNOS may be implicated in the moderate impairment of renal function, observed by others at 24 hours after liver I/R.

Total gastric transposition is better than partial gastric tube esophagoplasty for esophageal replacement in children

Whenever the surgeon uses the stomach as an esophageal substitute, either one of two techniques is generally performed: total gastric transposition or gastric tube esophagoplasty. No existing reports compare the complications associated with these two surgical procedures. The purpose of this study is to review the authors` experience with total gastric transposition and verify whether this technique is superior to gastric tube esophagoplasty in children by comparing the main complications with those reported in the publications of gastric tubes esophagoplasties in the English language literature published in the last 38 years. A total of 35 children underwent total gastric transposition according to the classical technique. Most of these patients (27, or 77.1%) had long gap esophageal atresia. The most frequently observed complications were compared to those reported in nine studies of gastric tube esophagoplasty comprising 184 patients. Mortality and graft failure rates were also compared. Seven patients (20.0%) presented with leaks, all of which closed spontaneously. Six children were reoperated, three experienced gastric outlet obstruction secondary to axial torsion of the stomach placed in the retrosternal space and the other three experienced delayed gastric emptying that required revision of the piloroplasty. There were two deaths (5.7%) and no graft failure. Strictures were observed in five patients (14.2%) and all of these were resolved with endoscopic dilatations. Six patients had diarrhea that spontaneously resolved. In the late follow-up period, all patients were on full feed and thriving well. The comparisons with gastric tube patients demonstrated that the total gastric transposition group presented with significantly less leaks and strictures (P = 0.0001 and 0.001, respectively). The incidence of death and graft failure was not statistically different. In conclusion, gastric transposition is as a simple technical procedure for esophageal replacement in children with satisfactory results, and is superior to gastric tube esophagoplasty.

Maxillary complete denture movement during chewing in mandibular removable partial denture wearers

To evaluate the pattern of maxillary complete denture movement during chewing for free-end removable partial dentures (RPD) wearers, compared to maxillary and mandibular complete denture wearers. Eighteen edentulous participants (group I) and 10 volunteers with bilateral posterior edentulous mandibles (group II) comprised the sample. Measures of mean denture movement and its variability were obtained by a kinesiographic instrument K6-I Diagnostic System, during the mastication of bread and a polysulphide block. Data were analysed using two-way anova (alpha = 0.05). Upper movement during chewing was significantly lower for group II, regardless of the test food. The test food did not influence the vertical or lateral position of the denture bases, but more anterior dislocation was found when polysulphide blocks were chewed. Group II presented lower intra-individual variability for the vertical axis. Vertical displacement was also more precise with bread as a test food. It can be concluded that mandibular free-end RPD wearers show smaller and more precise movements than mandibular complete denture wearers.