Ti and Zr complexes bearing guanidine-phenolate ligands: coordination chemistry and polymerization studies.

A series of group 4 bis(isopropoxide) complexes M[N^O]2(OiPr)2, stabilized by guanidine-phenolate N^O ligands, have been prepared and used as catalysts for the polymerization of unpurified rac-lactide under solvent-free conditions at 130 °C. The resulting polylactic acid (PLA) presented heterotactic bias (P r = 0.56-0.62) with molecular weights similar to those obtained in control experiments with Zr(OiPr)4·iPrOH, Ti(OiPr)4, and Sn(Oct)2. The molecular weights were lower than expected for living polymerization due to chain transfer and/or transesterification. Zr complexes were more active than the Ti homologues, with rate constants ranging from 1.17-3.21 × 10-4 s-1, comparable to that observed with the free guanidine-phenol ligands. The corresponding bis(guanidine-phenolate) titanium dichloride complexes Ti[N^O]2Cl2 were also prepared and tested in ethylene polymerization. The low activity (up to 1.1 kgPE mol-1 h-1) was associated to the strong electron-donating ability of the guanidine moiety and to the trans-N,N-cis-O,O-cis-Cl,Cl coordination mode of the guanidine-phenolate ligand.

N-heterocyclic carbenes and imidazole-2-thiones as ligands for the gold(I)-catalysed hydroamination of phenylacetylene.

Gold(I) complexes of 1-[1-(2,6-dimethylphenylimino)alkyl]-3-(mesityl)imidazol-2-ylidene (C^Imine(R)), 1,3-dimesitylimidazol-2-ylidene (IMes) and of the corresponding thione derivatives (S^Imine(R) and IMesS) were prepared and structurally characterised. The solid-state structure of the C^Imine(R) and S^Imine(R) gold(I) complexes showed monodentate coordination of the ligand and a dangling imine group that could bind reversibly to the metal centre to stabilise otherwise unstable catalytic intermediates. Interestingly, reaction of C^Imine(tBu) with [AuCl(SMe(2))] led to the formation of [(C^Imine(tBu))AuCl], which rearranges upon crystallisation into the unusual complex cation [(C^Imine(tBu))(2)Au](+), with AuCl(2)(-) as the counterion. The activity of the gold complexes in the hydroamination of phenylacetylene with substituted anilines was tested and compared to control catalyst systems. The best catalytic performance was obtained with [(C^Imine(tBu))AuCl], with the exclusive formation of the Markovnikov addition product in excellent yield (>95 %) regardless of the substituents on aniline.

A scoring model of factors associated with Candida glabrata candidemia among critically ill patients.

Candida species, including Candida glabrata (CG), are common causes of bloodstream infections among intensive care unit (ICU) patients. Many CG isolates have decreased susceptibility to fluconazole. Constructing a scoring model of factors associated with CG candidemia in ICU patients that can be used if fluconazole susceptibility testing is not readily available. We identified patients with candidemia that were admitted to the ICU of the Mayo Clinic in Rochester, Minnesota from 1998 to 2006. Using patient demographical and clinical data abstracted via chart review, a multivariable logistic regression model was developed to distinguish those with CG candidemia. We identified 246 patients with candidemia including 68 CG cases. Multivariable analysis identified four independent factors associated with CG candidemia: absence of renal failure, less than 7 days in the hospital, abdominal surgery and fluconazole use. The predictive ability of the model, based on the c-statistic, was 0.727. In a large ICU cohort, a scoring model that included four risk factors, which are readily ascertainable at the bedside, was created to distinguish candidemia due to CG from other causes of candidemia. The identification of risk factors associated with CG candidemia could aid physicians in the selection of the optimal initial antifungal therapy.

[Workplace chemical hazard evaluation: methodological and regulatory aspects]. / Aspetti metodologici e normativi per l'analisi dei Rischi Chimici Occupazionali.

In workplace health and safety chemical hazard identification methodological aspects are of fundamental importance. Italian and EC regulations, extensively growing, as the Legislative Decree 81/2008 and the incoming Reach-CLS, are facing an 'upgraded' industrial hygienist synergistically integrated with other OHS professionals. The production-process and organizational-tasks analysis are the basis for hazards evaluation and pre-condition for an appropriate adoption of preventive measures. The tool that should be taken are case specific and diversified: risk analysis, modeling, index methods, environmental and exposure assessment monitoring, PHA and HRA, extensive literature and online data-bases. In borderline cases it is also mandatory an assessment forwarding both the precautionary and reasonableness principles, but always, an highly professional approach is essential.

Coordinatively- and electronically-unsaturated square planar cobalt(iii) complexes of a pyridine dianionic pincer ligand.

A series of low-valent Co(iii) square planar complexes supported by a dianionic pincer ligand bis(arylamido)pyridine ([NNN]2-) was synthesized, including the first structurally characterized square planar hydroxide complex ([NNN]Co(OH), 4) of a 3d transition metal in the +3 oxidation state. The magnetic properties of the Co(iii) complexes were highly dependent on the charge of the complex and on the coordination environment of the metal. The diamagnetic cationic complex {[NNN]Co(py)}BF4 (2) can be converted to neutral paramagnetic complexes [NNN]Co(OR) (R = Ph 3a, iPr 3b, and H 4) by a simple substitution of the ancillary pyridine ligand in 2. The double bond character between the metal and the anilido nitrogen was evident from short Co-N2,3 bond lengths in the solid-state structures, and further supported by density functional theory calculations. Complex 2 showed well-behaved redox processes at -0.93 and +0.70 V assigned to CoII/III and [NNN]2-/1- redox couples, respectively. In contrast, both complexes 3a and 4 showed some irreversibility in redox processes on either cobalt or ligands.

Acute Presentation of Lumbar Spinal Schwannoma Due to Torsion: A Case Report.

Although schwannomas are common spinal tumors with insidious presentations, acute neurological deterioration is an extremely rare manifestation that can occur in the setting of tumor torsion and infarction. The present case reports an unusual presentation of a spinal schwannoma that underwent torsion and infarction. A 65-year-old male presented initially with acute radicular pain progressing to cauda equina syndrome and confusion. MRI of the lumbar spine revealed an intradural extramedullary lesion at the level of L1/L2 measuring 1.1x0.9 cm. Intraoperatively, a reddish mass was seen caudally twisted around itself. Gross total resection was achieved with a final diagnosis of schwannoma with areas of infarction. At his six week follow up clinical visit, the patient was asymptomatic and his neurological exam was normal. The neurosurgeon should be aware of such atypical radiographic and clinical presentation amongst the spectrum of clinical manifestation of these nerve sheath tumors.

Presence of serotonin1A (5-HT1A) receptor mRNA without binding of [3H]-8-OH-DPAT in peripheral blood mononuclear cells.

The authors investigated the presence of serotonin receptor type 1A (5-HT1A) as labeled by the specific ligand 3H-8 hydroxy-2-(di-N-propylamino)tetralin (3H-8-OH-DPAT) in saturation experiments, and the expression of the mRNA encoding them, in human peripheral blood mononuclear cells (PBMC). In situ hybridization experiments were performed as well. The results, showing that the binding of [3H]-8-OH-DPAT to lymphocyte membranes increased linearly up to 100 nM without reaching saturation, may indicate that the 3H-8-OH-DPAT was not specifically labeling the 5-HT1A receptor. By contrast, the expression studies revealed 5-HT1A mRNA in PBMC. These findings suggest that, despite the presence of mRNA, 5-HT1A receptors are not expressed in PBMC, at least in healthy controls.

Assessment of vascularized fibular graft one year after reconstruction of the wrist after excision of a giant-cell tumour.

We report a patient in whom the distal radius was resected for a giant cell tumour and the bone defect was replaced using a vascularized proximal fibular graft. The graft was viable and hypertrophied and normal callus formed on the distal radius. Due to chronic instability of the wrist the patient underwent revision arthrodesis 1 year after resection. Microscopic studies of the epishyseal region of the fibula showed wide necrosis of the graft with active creeping substitution. Despite the good technical result of the vascularized fibular graft, the vascularization was incomplete in the proximal epiphysis. We discuss possible reasons for this.

The surgical treatment of thoracolumbar metastases.

Between 1990 and June 1995 a total of 41 patients affected with vertebral metastases caused by neoplasm with different histotypes were treated at the Ist Clinical Orthopaedics and Traumatology Division at the University of Turin. A method proposed by J. Harms was used, nearly always involving a combined anterior and posterior surgical approach. At the Division of Orthopaedics of the Ospedale Maria Adelaide in Turin between 1993 and June 1995 a total of 16 patients affected with vertebral metastases caused by neoplasms of different histotypes were treated. Decompression and posterior stabilization alone using Diapason instrumentation was prevalently performed. Patients with a life expectancy of at least 6 months were treated. Follow-up was obtained by interviewing the patients over the phone during August of 1995. In the cases at the Ist Division of Orthopaedics the number of levels that were instrumented were on the average 2.5, at follow-up 83% of the patients stated that they were satisfied, while only 7.4% were unsatisfied. In the second series (Ospedale Maria Adelaide) the number of levels instrumented was on the average 8, at follow-up 62.5% of the patients said that they were satisfied, while 31.8% said that they were unsatisfied.

A model for the organization of a regional bank for musculoskeletal tissues in Italy.

The national and local need for human tissues to be used in transplants is a high one, and constantly growing. Human, scientific and financial resources involved in guaranteeing safe and high-quality tissues as defined by the national guidelines for musculoskeletal tissue banks are considerable. For this reason we need to find adequate solutions to the problem of guaranteeing sufficient availability of tissues with the lowest cost possible for supply. The Piedmont Region Musculoskeletal Tissue Bank, which is located in an Azienda Ospedaliera, has been organized to guarantee the quality of its tissues via biological validation and scientific-clinical coordination; it makes use of the collaboration of removal centers that send tissues taken from the central bank for certification and identifies several centers for preservation; it collaborates with a bank of national importance for tissue processing. The publication of regulations and tariffs based on cost analysis improves the procedures.

CT evaluation pre- and post-percutaneous ablation by radiofrequency of osteoid osteoma. Preliminary experience.

PURPOSE: Evaluation of bone remanagement after treatment by thermoablation of osteoid osteoma (OO) by CT scan. MATERIAL AND METHOD: Nine cases of OO (8 in the limbs, 1 in the pelvis) following biopsy were treated by CT-guided thermoablation. Clinical results, complications, density of tissues treated by CT scan (pre-postop, 6, 12 months) are evaluated. RESULTS: Absence of complications, regression of pain over 2 weeks, resumption of sports activity in 1 month. Bone density after treatment increases but even after 1 year it is much lower than normal levels. CONCLUSIONS: Bone remodeling after thermoablation of OO requires much time, the process is still visible 12 months later by CT scan. CT scan is an adequate method, not only for diagnosis and treatment, but also for follow-up, capable of evaluating in time the changes in density of the site of the lesion, which is useful for a comparison in case of postoperative pain of doubtful origin.

The integration of vascular surgical techniques with oncological surgical protocols in the treatment of soft tissue sarcomas of the limbs.

Soft tissue tumors, involving the vascular bundle, require a particular surgical approach: oncological and vascular surgical techniques must be integrated in order to perform a limb-saving surgery with adequate margins. Thirty-six soft tissue sarcomas of the thigh and popliteal region were treated from June 1999 to September 2002. Nineteen cases involving the vascular bundle were analysed and placed in two groups according to imaging and clinical information: Group A, 14 patients, with tumors close to femoral vessels without adventitial infiltration, and Group B, 5 patients, with vascular infiltration. Group A was treated with vascular blunt dissection performing adventitial excision. Group B was treated with vascular "en-bloc" resection and reconstruction. Imaging and clinical information together with surgical techniques, strategies and complications were analysed in order to plan the surgical approach in neoplastic vascular bundle involvement.

Echocolor Power Doppler with contrast medium to evaluate vascularization in lesions of the soft tissues of the limbs.

PURPOSE: Echocolor Power Doppler with contrast medium forms a non-invasive vascular image; the purpose of the study is to evaluate the effectiveness in differentiating benign and malignant tumors in the soft tissues of the limbs. MATERIAL AND METHOD: Echocolor Power Doppler with contrast medium was used to study 80 patients with swelling in the soft tissues of the limbs: there were 54 benign lesions, 22 sarcomas, and 4 aggressive desmoid fibromatoses. RESULTS: Were identified 4 patterns of wash-in and wash-out curves that could be correlated to the histological diagnosis: type I was present in 85% of benign lesions, type III in 91% of malignant lesions and in 3.7% of the benign ones, type II in aggressive fibromatoses, anomalous type in 4 benign lesions and 2 sarcomas; the curve was absent in 2 benign lesions. CONCLUSIONS: Power Doppler Echocolor with contrast medium can become a useful method to be associated with traditional imaging methods in the differential diagnosis of swelling of the soft tissues of the limbs.

[Placenta accreta with placenta previa after previous cesarean sections--a growing danger in modern obstetrics].

The increased rate of cesarean sections in recent decades has brought with it an increase in the frequency of placenta accreta. There are direct correlations between previous cesarean deliveries and also maternal age, with the risk of placenta accreta. There is also a direct correlation between placenta accreta and placenta previa. The risk of placenta accreta in women who have had placenta previa is 2% for those younger than 35 years and with no history of uterine surgery. The risk increases to 39% for those over 35 who have had 2 or more cesarean sections. We present 3 cases of placenta accreta admitted in 15 months, all of whom had a history of cesarean sections. The frequency of placenta accreta in our hospital is 1:1,579 deliveries, in line with the 1:1,420 in the literature. We consider hysterectomy the treatment of choice for this serious complication. When performing a cesarean in cases of placenta previa with a history of cesarean sections, the possibility of placenta accreta should be considered.

Formation of a dicationic ruthenium benzyl complex by halide abstraction from a Grubbs-type second-generation benzylidene.

A ruthenium benzylidene complex with a neutral bidentate N-heterocyclic carbene was prepared and evaluated in ring-closing metathesis of diallyl substrates. Reaction with AgPF6 to generate a four-coordinate complex produced an unexpected dicationic ruthenium benzyl degradation product through nucleophilic attack of the NHC ligand on the benzylidene carbon.

Titanium(IV) imido complexes of imine imidazol-2-imine ligands.

Free imine imidazol-2-imine ligands with two different substitution patterns have been isolated for the first time and they were found to exist as an equilibrium mixture of geometric and mesomeric isomers. The relative ratios of these isomers are dependent on both the nature of the substituents and of the solvent. The synthesis of the titanium(IV) alkyl and arylimido complexes of these ligands was unexpectedly found to be very selective and was successfully achieved only with the lesser sterically-demanding 2,4,6-trimethylphenyl derivative IMesN^Imine 2a. The solid-state structure of the alkylimido complex further confirms the zwitterionic character of the ligand. The isolated titanium imido complexes were found to be active catalysts for the polymerisation of ethylene.

New stable aryl-substituted acyclic imino-N-heterocyclic carbene: synthesis, characterisation and coordination to early transition metals.

The synthesis of the bulky 1-(1-arylimino-2,2-dimethylpropyl)-3-(aryl)imidazolium salt from the corresponding imidazole and the activated imidoyl chloride is presented. The absence of acidic protons adjacent to the iminic carbon allowed for the first isolation of an imino-N-heterocyclic carbene of this ligand class. The free carbene was isolated, structurally characterised, and coordinated to titanium, zirconium, hafnium and chromium. The resulting metal halide complexes were fully characterised and were tested at room temperature and atmospheric pressure for their activity as ethylene polymerisation catalysts. The Zr(IV) complex was found to be the most active with a productivity of 140 kg PE mol M(-1) h(-1).

Coordination study of a new class of imine imidazol-2-imine ligands to titanium(IV) and palladium(II).

A new family of ligand precursors, N-(1-(2,6-dimethylphenylimino)ethyl)-1,3-bis(aryl)imidazol-2-imine hydrochloride, wherein aryl = 2,4,6-trimethylphenyl (3a) and 2,6-diisopropylphenyl (3b), was prepared and structurally characterised. Deprotonation of the salts yields molecules with delocalised pi-electrons, leading to zwitterionic mesomeric structures. Titanium(IV) (4a,b) and palladium(II) (5a,b) complexes were isolated and also structurally characterised. Two different coordination modes were observed where the ligand is either coordinated in a bidentate fashion as expected, or in a monodentate fashion through the more basic aryliminic nitrogen atom.

First aryl-substituted acyclic imino-N-heterocyclic carbene ligand precursor: synthesis, characterisation and coordination with silver(I) and copper(I).

The first aryl-substituted imino-N-heterocyclic ligand precursor was prepared and structurally characterised, along with the corresponding silver(i) and copper(i) chloride complexes. An unusual T-shape coordination mode for the copper centre was observed.