bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthesis, Structure and Reactivity of PH‐Phosphoraneiminato‐ and Iminophosphoraneiminato Group 4 Transition‐Metal Complexes
Authors: Raab Michael , Tirreé Jürgen , Nieger Martin , Niecke Edgar 
Published: May 2003

AbstractThe versatile coordination chemistry of the well‐investigated phosphoraneiminato‐ligand R3PN— (I) was extended by the successive introduction of protons to the phosphorus atom. The position of the resulting equilibrium between the NH‐phosphanylamido‐ [R2P‐NH—] and the PH‐phosphoraneiminato‐form [R2HP=N—] is affected by the Lewis acidity of the coordinated metal fragment. Experimental studies on complexes with various substitution patterns at the group 4 metal center R2HP=N[M] (II) were unambiguously confirmed by DFT‐calculations. The isolation of group 4 PH‐dihydrido‐phosphoraneiminato‐complexes RH2P‐N[M] (III) is prevented by the low thermodynamic stability of the target molecules, also supported by the results of ab initio calculations. However, an access to the by then unknown transition‐metal substituted iminophosphanes RP=N[M] (IV) was verified for the first time.Within extensive studies on the coordination chemistry of bis(imino)phosphoranes RP(=NR′)(=NR″), several species of group 4 complexes R(R′N=)P=N[M] (V) were isolated and structurally characterized. In this case, investigations on the NH/PH‐tautomerism were performed exclusively on theoretical level, because the required educts are experimentally non‐accessible due to their kinetic instability.
Theoretical Studies of Inorganic Compounds. 27 Quantum Chemical Investigations of Transition Metal Nitrido Complexes with a TM‐N‐E Linkage (E = Main Group Element)
Authors: Spuhler Philipp , Lein Matthias , Frenking Gernot 
Published: May 2003

AbstractIt is reported about quantum chemical DFT calculations of various transition metal (TM) nitrido complexes which contain a TM‐N‐E linkage. The goal is to elucidate the nature of the TM‐N‐E bonding situation with modern quantum chemical tools. Five comparative investigations have been carried out. (a) Comparison of the N‐donor ability in the nitrido complexes Cl3W‐N‐ECln where ECln = NaCl, MgCl2, AlCl3. (b) Comparative analysis of the bonding situation in Cl4W‐N‐X where X = Na, MgCl, AlCl2, SiCl3, PCl2, SCl, Cl. (c) Comparison of the structure and bonding in Cl5W‐NPH3, Cl5W‐OPH3+, Cl4W‐(NPH3)(OPH3)+. (d) Comparative analysis of the bonding situation in Cl5Ta‐OPH3, Cl5W‐NPH3, Cl5Re‐CPH3. (e) Energy decomposition analysis of the bonding of the isolobal ligands NPH3 and Cp with WCl5.
Ein Beitrag zu Rhenium(II)‐, Osmium(II)‐ und Technetium(II)‐Thionitrosylkomplexen vom Typ [M(NS)Cl4py]—: Darstellung, Strukturen und EPR‐Spektren
Authors: Reinel Martina , Höcher Thomas , Abram Ulrich , Kirmse Reinhard 
Published: May 2003

AbstractDie Umsetzung von [ReVINCl4]— und [OsVINCl4]— mit S2Cl2 führt über die nicht als reine Substanzen isolierbaren Thionitrosylkomplexe [MII(NS)Cl4]— (M = Re, Os) nach Zugabe von Pyridin zu den stabilen Verbindungen trans‐(Ph4P)[OsII(NS)Cl4py], trans‐(Hpy)[OsII(NS)Cl4py], trans‐(Ph4P)[ReII(NS)Cl4py] und cis‐(Ph4P)[ReII(NS)Cl4py].Die Kristallstrukturanalysen ergeben für trans‐(Ph4P)[OsII(NS)Cl4py] (monoklin, P21/n, a = 12, 430(3)Å, b = 18, 320(4)Å, c = 15, 000(3)Å, β = 114, 20(3)°, Z = 4), trans‐(Hpy)[OsII(NS)Cl4py] (monoklin, P21/n, a = 7, 689(1)Å, b = 10, 202(2)Å, c = 20, 485(5)Å, β = 92, 878(4)°, Z = 4), trans‐(Ph4P)[ReII(NS)Cl4py] (triklin, P1¯, a = 9, 331(5)Å, b = 12, 068(5)Å, c = 15, 411(5)Å, α = 105, 25(1)°, β = 90, 23(1)°, γ = 91, 62(1)°, Z = 2) und cis‐(Ph4P)[ReII(NS)Cl4py] (monoklin, P21/c, a = 10, 361(1)Å, b = 16, 091(2)Å, c = 17, 835(2)Å, β = 90, 524(2)°, Z = 4) Bindungswinkel (M‐N‐S) zwischen 168‐175° und damit nahezu lineare NS‐ Koordination. Das Metallatom ist jeweils oktaedrisch koordiniert.Die ReII‐Thionitrosylkomplexe (5d5‐„low‐spin”︁‐Konfiguration, S = 1/2) wurden im X‐Band EPR‐spektroskopisch im Temperaturbereich 295 > T > 130 K untersucht. Neben dem Nachweis der bei der Reaktion von [ReVINCl4]— mit S2Cl2 gebildeten Komplexe wurden EPR‐Untersuchungen an diamagnetisch verdünnten Pulvern und Einkristallen des Systems trans‐(Ph4P)[ReII/OsII(NS)Cl4py] durchgeführt. Die erhaltenen Parameter wurden zur Bestimmung der Spindichteverteilung in den untersuchten Komplexen verwendet.[TcVINCl4]— reagiert mit S2Cl2 unter Bildung von [TcII(NS)Cl4]—, das aber unter Eliminierung von S8 wieder zum Ausgangskomplex zerfällt. Die Reaktion wurde EPR‐spektroskopisch verfolgt.
Synthesis of Nitrido(phthalocyaninato)metal(V) Complexes RnPcMN (M = Re, Mo, W) and New Compounds with Nitrido‐Bridges between Rhenium and Elements of the Third Main Group
Authors: Verma Sanjiv , Hanack Michael 
Published: May 2003

AbstractNew tetra‐ and octasubstituted nitrido(phthalocyaninato)metal(V) complexes RnPcMN (M = Re, Mo, W) were synthesized to obtain soluble nitrido‐bridged phthalocyanines. Phthalocyanines with nitrido bridges between rhenium and boron, aluminium, gallium and indium, respectively, were synthesized from nitrido(tetra‐tert.‐butylphthalocyaninato)rhenium(V) complex, tBu4PcReN and suitable electrophilic reagents like BCl3, B(C6F5)3, BPh3, BEt3, AlCl3, GaCl3, GaBr3, InCl3, etc. The nitrido‐bridged compounds prepared show different stabilities depending on the substituents at the boron atom. Additionally, the possibility to increase the nucleophilicity of (C5H11)8PcWN by reducing this complex with C8K was studied. The reaction of the reduced complex with electrophiles, e.g. with tBuMeSiCl, Ph3SiCl and Me3GeCl indicates the formation of nitrogen‐bridged complexes.
Steroid‐free immunosuppression during and after liver transplantation – a 3‐yr follow‐up report
Authors: Pirenne Jacques , Aerts Raymond , Koshiba Takaaki , Gelder Frank Van , Roskams Tania , Schetz Marie , Verhaegen Marleen , Lauwers Peter , Fevery Johan , Nevens Frederik 
Published: May 2003

Abstract:  Background/aims: Steroids are traditionally used in liver transplantation as a part of a triple or quadruple immunosuppressive regimen. Steroids act non‐specifically and cause multiple side‐effects. Most liver transplantation centers reduce the dosage of steroids and eventually withdraw them after various time intervals. A few steroid‐free trials have been recently conducted after liver transplantation but long‐term data are not yet available. In addition, in these trials steroids were usually given during surgery. We report the long‐term (median = 40 months) follow‐up data of a prospective pilot study designed to determine whether liver transplantation could be performed with no steroids at all (neither during nor after surgery).Methods: Twenty‐one consecutive liver transplantations in 20 adult patients between August 1998 and July 1999 were prospectively included in an ab initio steroid‐free immunosuppressive protocol. Mean age was 54 yr (40–67 yr). Tacrolimus (through levels, 8–10 ng/mL) and azathioprine (1–2 mg/kg) were started after liver transplantation. Patients were not given steroids during or after liver transplantation except in the event of rejection or in case of tacrolimus or azathioprine toxicity requiring significant dose reduction and/or withdrawal.Results: There has been no case of primary graft dysfunction or non‐function. Eleven of 21 liver transplantations (52%) received no steroids throughout the whole study. Rejection developed in five of 21 liver transplantations (23.5%). These rejections responded to standard i.v. steroids (plus ATG in one patient), followed by an oral steroid taper stopped 3 months after rejection. Steroids were transiently given in six liver transplantations for non‐immune reasons: two with tacrolimus‐induced neurotoxicity, three cases where azathioprine was discontinued, and one for an allergic reaction; four of these six patients are off steroids at last follow‐up. The 3‐yr graft and patient survival is 95 and 100%, respectively.Conclusions: Steroids are not necessary in more than 50% of liver transplantations. Steroids were transiently needed to treat acute rejection in 23.5% liver transplantations and for toxicity of calcineurin inhibitors or azathioprine or other reason in 28%. Of the patients who received steroids, the majority (70%) was eventually taken off steroids. This prospective single‐center pilot study shows that liver transplantation without steroids is feasible and yields no penalty in terms of acute and chronic rejection, immune graft loss, graft function, patient and graft survival.
Chronic liver disease in kidney recipients with hepatitis C virus infection
Authors: Giordano Helena M , França Alex VC , Meirelles Luciana , Escanhoela Cecília AF , Nishimura Nancy F , Santos Raquel LS , Quadros Kélcia RS , Mazzali Marilda , Alves‐Filho Gentil , Soares Elza C 
Published: May 2003

Abstract: Background:  The prevalence of anti‐hepatitis C virus (HCV) positive test is higher among patients in dialysis and in kidney recipients than in general population. Hepatitis C virus infection is the main cause of chronic liver disease in renal transplant patients. Liver biopsy and virological analysis were performed to clarify the grade of liver damage in kidney recipients.Methods:  Renal recipients patients with at least 5 yr under immunosuppression were submitted to clinical and laboratory analysis. Patients who tested anti‐HCV positive were candidates to liver biopsy with no regard to transaminase levels.Results:  Forty‐five patients tested anti‐HCV positive and 42 anti‐HCV negative. Twenty‐six anti‐HCV and RNA‐HCV positive patients were submitted to liver biopsy. Seventy‐three percentage of these patients presented chronic active hepatitis, from these only one patient presented cirrhosis. Only 29% of the anti‐HCV positive group presented elevated alanine aminotransferase levels. Anti‐HCV positive patients presented longer previous time on dialysis and less rejection episodes than the group anti‐HCV negative (p < 0.05). All anti‐HCV positive patients but one tested RNA‐HCV positive by polymerase chain reaction (PCR).Conclusions:  In this series the prevalence of anti‐HCV positive is 51.7%. Most of the patients presented liver damage in histology caused by HCV. However, we found only mild or minimal fibrosis and inflammatory activity grade, despite 10 yr of HCV infection and 5 yr of immunosuppressive treatment. Only one patient presented cirrhosis (4%). Performing serial liver biopsies in a long‐term follow‐up is needed to clarify the impact of HCV infection in renal transplant patients.
The impact of mycophenolate mofetil dosing patterns on clinical outcome after renal transplantation
Authors: Pelletier Ronald P , Akin Baris , Henry Mitchell L , Bumgardner Ginny L , Elkhammas Elmahdi A , Rajab Amer , Ferguson Ronald M 
Published: May 2003

Abstract: Background:  Mycophenolate mofetil (MMF) has proven to be a very effective drug for the prevention of acute rejection following renal transplantation when dosed as prescribed at 2 or 3 g/d. However, circumstances arise in clinical transplantation where the dose must be lowered, either to avoid drug toxicity or because of concurrent infection. The impact on the incidence of acute rejection and graft survival when the MMF dose must be lowered has not previously been investigated.Methods:  In this study, a cohort of 721 kidney transplant recipients who received immunosuppression using MMF in conjunction with cyclosporine and prednisone and OKT3 (n = 425) or Simulect (n = 296) induction were evaluated. Clinical outcomes were compared and contrasted between patients with and without MMF dose changes within the first year post‐transplantation.Results:  The majority of patients (70.3%, n = 507) had at least one dose change within the first post‐transplant year. Compared with the 214 patients who did not have a dose change, these patients had a much higher incidence of acute rejection within the first post‐transplant year (23.3% vs. 3.7%, p < 0.001). This resulted in a significantly decreased 3‐yr death‐censored graft survival (76.3% vs. 88.3%, p = 0.003). The incidence of acute rejection for patients who had a dose change was highest if the dose change occurred within the first post‐transplant month (34.4%). The incidence of acute rejection for the dose change patients was influenced by recipient ethnicity (African‐American vs. Caucasian) and the type of induction agent used (OKT3 vs. Simulect).Conclusion:  Altering the dose of MMF within the first post‐transplant year correlated with a significantly worse clinical outcome in this cohort of renal transplant recipients. These data suggest that avoidance of MMF dose changes within the first year after renal transplantation would result in improved graft survival.
The use of an anti‐CD25 monoclonal antibody and mycophenolate mofetil enables the use of a low‐dose tacrolimus and early withdrawal of steroids in renal transplant recipients
Authors: Kuypers DRJ , Evenepoel P , Maes B , Coosemans W , Pirenne J , Vanrenterghem Y 
Published: May 2003

Abstract: Background: Reducing calcineurin‐inhibitor‐induced nephrotoxicity and simultaneously avoiding long‐term steroid related side‐effects is a desirable goal in renal transplantation. We examined the hypothesis that using anti‐CD25 monoclonal antibody induction and mycophenolate mofetil (MMF) would allow the lowering of target pre‐dose blood concentrations of tacrolimus immediately after transplantation and subsequently stopping steroids at 5 months.Methods: Eighty‐two kidney recipients were enrolled in a single‐center study comparing two tacrolimus‐based protocols. Group I (n = 41) patients received a standard‐dose tacrolimus (blood concentration 10–15 ng/mL) with MMF and a standard dose corticosteroid. Group II (n = 41) patients were treated with a low‐dose tacrolimus (blood concentration 5–10 ng/mL) and MMF, a low‐dose corticosteroid (stopped after 5 months) and induction with daclizumab.Results: Patient (95.1 versus 100%) and graft survival (92.6 versus 97.5%) at 1 yr were not different between groups. Patients of group II experienced significantly less acute rejections than group I (17.1 versus 41.4% p = 0.03). Delayed graft function occurred less often in group II (5 versus 12% p = 0.43). Graft function at 1 yr was significantly better in group II (serum creatinine 1.49 versus 1.69 mg/dL and creatinine clearance 59.6 versus 49 mL/min; p < 0.05). Corticosteroids could be stopped after 5 months in 82.9% of group II patients.Conclusion: A regimen consisting of anti‐CD25 monoclonal antibody induction and MMF allows the safe and efficient use of low‐target pre‐dose trough concentrations of tacrolimus and enables the early discontinuation of steroids. Preliminary results indicate a better 1‐yr graft function compared to a normal‐dose tacrolimus regimen.
Pancreas transplantation in crossmatch‐positive recipients
Authors: Khwaja Khalid , Wijkstrom Martin , Gruessner Angelika , Noreen Harriet , Sutherland David ER , Humar Abhinav , Kandaswamy Raja , Gruessner Rainer WG 
Published: May 2003

Abstract: Background: Prolonged cold preservation time can unfavorably affect outcome in pancreas transplantation. To reduce this ischemic time, cadaver pancreas grafts, in selected cases, are sometimes transplanted before crossmatch results are known. We report our experience with pancreas transplants in recipients with either current or historically positive T‐ or B‐cell crossmatches.Methods: Crossmatch‐positive pancreas transplants were identified using a computerized database. T‐cell crossmatches were performed using an antihuman‐globulin‐augmented complement‐dependent cytotoxicity (CDC) test; B‐cell crossmatches were performed using an extended incubation CDC test. All patients received anti‐T‐cell induction therapy and either cyclosporine (1987–1993) or tacrolimus‐based (1994–2001) immunosuppression. More recent recipients (2000–2001) also received intravenous gamma globulin and postoperative plasmapheresis.Results: Between October 1, 1987 and March 31, 2001, of a total of 1076 pancreas transplants performed, 59 (5.48%) were crossmatch‐positive. Of these, 8 had a current T‐cell‐positive crossmatch and 15 had a current B‐cell‐positive crossmatch. One recipient was both current B‐ and T‐positive, and the rest were past B‐ and/or T‐cell positive. One‐year pancreas graft survival for current T‐ and B‐cell crossmatch‐positive transplants was 63% and 67%, respectively. T‐ or B‐cell crossmatch‐negative transplants had a 1‐yr survival of 70%. In the T‐cell crossmatch‐positive group, four grafts are still functioning (follow‐up range, 2–12 yr), one patient died with a functioning graft at 4 months, and four grafts failed (one each from pancreatitis, infection, primary nonfunction, and vascular thrombosis). No grafts were lost to rejection. In the B‐cell crossmatch‐positive group, six grafts are still functioning (follow‐up range, 2–11 yr) and nine have failed (four from chronic rejection, three from vascular thromboses, and two from pancreatitis). Crossmatch‐positive cases were significantly more likely to be retransplants (70.8%) than crossmatch‐negative cases (14.8%, p < 0.0001). In a multivariate analysis, crossmatch positivity did not affect pancreas graft outcome, whereas retransplants had a significant impact on outcome (relative risk 1.84, p < 0.0001).Conclusions: (i) Pancreas transplants performed in the setting of a positive current crossmatch may have long‐term function. (ii) With current immunosuppressive protocols, graft loss from hyperacute and acute rejection may be prevented in current crossmatch‐positive pancreas transplants. Chronic rejection was only seen in B‐cell crossmatch‐positive cases. (iii) High rates of technical graft loss in crossmatch‐positive cases may reflect a high frequency of retransplants in this group.
Two‐ to three‐fold increase in blood tacrolimus (FK506) levels during diarrhea in liver‐transplanted children
Authors: Berengue Juan Iglesias , López‐Espinosa Jesús Alberto , Ortega‐López Juan , Sánchez‐Sánchez Luz , Castilla‐Valdes Patricia , Asensio‐Llorente Marino , Margarit‐Creixell Carlos 
Published: May 2003

Abstract: Background: The diagnosis and treatment of diarrhea in liver transplant recipients often pose a challenge owing to the variety of infectious and non‐infectious causes. However, diagnosis is principally focused on ruling out an infectious etiology. Tacrolimus, an immunosuppressive agent generally used after liver transplantation, is absorbed mainly from the duodenum through the upper jejunum. It can be assumed that metabolism of the drug will be influenced by diarrhea.Methods: Four liver transplant recipients who developed an episode of acute gastroenteritis. Infectious etiology was confirmed; trough tacrolimus levels were measured before, during and after gastroenteritis.Results: All patients presented a two‐ to three‐fold increase in blood tacrolimus levels after the onset of gastroenteritis.Conclusions: Until the role played by the intestine in the metabolism of tacrolimus is fully understood, it is prudent to recommend early dose reduction of tacrolimus and careful monitoring of trough levels during diarrheal disorders of any nature in pediatric liver‐transplanted patients.
A comparative kinetic study on the singlet molecular oxygen‐mediated photoxidation of α‐ and β‐chymotrypsins
Authors: Biasutti M.A. , Posadaz A. , García N.A. 
Published: May 2003

Abstract: Kinetic aspects of the sensitized photooxidation of α‐ and β‐chymotrypsins have been studied at pH 6 and 8. The sensitization, employing classical O2(1Δg)‐photogenerators, such as xanthene dyes, is a kinetically intricate process because of the presence of ground state dye–protein associations and to the simultaneous participation of superoxide ion and singlet molecular oxygen [O2(1Δg)].Both proteins, that possess the same distribution pattern of photooxidizable amino acids, suffer a pure O2(1Δg)‐mediated photodynamic attack, using the carbonylic sensitizer Perinaphthenone. Overall and reactive rate constants for the O2(1Δg)‐quenching (in the order of 108 and 107/M/s, respectively), and rates of oxygen consumption determined by time‐resolved, spectroscopic and polarographic methods indicate that α‐ and β‐chymotrypsins are less photooxidizable at pH 6, as a result of an enhancement of the O2(1Δg)‐physical quenching component. In general terms, β‐chymotrypsin exhibits the greater overall proclivity to interact with O2(1Δg), whereas structural factors, possibly evidenced by a higher exposure of the reactive tryptophan residues, impart an increased photooxidation degree to the proteins at pH 8, specially to the α‐chymotrypsin.
Valproate
Authors: Bowden Charles L 
Published: May 2003

Objectives: This article summarizes the role of valproate as a treatment for bipolar disorder and related conditions.Methods: Published studies and reviews were systematically reviewed. Results from randomized, parallel group, double‐blind, placebo‐controlled studies that included an active comparator are emphasized.Results: Valproate is an effective treatment for manic patients. Valproate was superior to placebo in one 1‐year randomized, parallel group study in rate of recurrence requiring discontinuation, rate of depression requiring discontinuation, total early termination and time to 25% of patients relapsing with mania, and in controlling mild depressive symptoms. On some measures, including time to development of a manic episode, valproate did not differ from placebo. Assessments of maintenance efficacy of valproate and other putative prophylactic treatments for bipolar disorder are problematic, because of the need to analyze multiple indices of efficacy, and practical and ethical issues that limit generalizability of results of placebo‐controlled studies. Valproate has some advantages over lithium in treatment of mania for persons with more severe illnesses. Valproate benefits a broader spectrum of bipolar conditions than lithium. Valproate appears at best modestly effective for bipolar depression. Used in combination with several other treatments, additive benefits result, that are greater than with any of the treatments as monotherapy. Side effects are generally mild and manageable, particularly with divalproex. Weight gain and pharmacokinetic interaction with lamotrigine are perhaps the most consistent problems in use. Valproate contributes to neural tube defects if taken during the first trimester of pregnancy, and this risk must be conveyed to women.Conclusions: Valproate is an effective and useful treatment for bipolar disorder. Studies clarifying its spectrum of efficacy, its safety and efficacy in combination regimens, and its mechanisms of action are warranted.
Recent concepts in plaque formation
Authors: Bernimoulin J.‐P. 
Published: May 2003

AbstractDental plaque is an adherent, bacterial film, and is the main pathological agent for periodontal diseases. The formation of dental plaque can occur both supragingivally and subgingivally. The development of plaque is a three‐step process. Following the formation of a pellicle, pioneer micro‐organisms will adhere to it, proliferate and form colonies. The final stage involves the aggregation of filamentous organisms and spirochetes into a cohesive biofilm. Many products of the plaque bacteria reach the subepithelial tissue, causing inflammatory responses such as increased vascularity and leukocyte diapedesis. Both supragingival and subgingival plaque may form a hard, mineralized mass called calculus. The surface of calculus harbours bacteria, which may exacerbate the inflammatory responses. An effective oral antiseptic must be active against a wide range of Gram‐positive and Gram‐negative bacterial species, including streptococci and fusobacteria. Ideally, an effective agent would also penetrate the plaque biofilm. Data show that essential oil and chlorhexidine mouthwashes have the broadest antimicrobial effects.