On the use of 17O NMR for understanding molecular and silica-grafted tungsten oxo siloxide complexes.

17O-labelled tungsten siloxide complexes [WOCl2(OSitBu3)2] (1-Cl) and [WOMe2(OSitBu3)2] (1-Me) were prepared and characterized by 17O MAS NMR, with input from theoretical calculations of NMR parameters. Guidelines linking 17O NMR parameters and the coordination sphere of molecular and silica-grafted tungsten oxo species are proposed. The grafting of 1-Me on SiO2-700 afforded material 2, with surface species [(SiO)WOMe2(OSitBu3)] as shown by elemental analysis, IR and 1H and 13C MAS NMR. The DFT calculations of the grafting mechanism are in line with the observed reactivity. They indicate the occurrence of several isomeric species of close energy for the grafted W centers, precluding efficient 17O MAS NMR studies. The lack of catalytic activity in olefin metathesis and ring-opening olefin metathesis polymerization indicates that initiation by α-H elimination is not operative in 2, contrary to related tungsten surface species, which illustrates the crucial influence of the nature of the metal coordination sphere.

Solid-state NMR of quadrupolar nuclei for investigations into supported organometallic catalysts: scope and frontiers.

The rational development of heterogeneous catalysts is a prerequisite for improving current catalytic technologies. One of the most successful approaches to achieve this goal is the grafting of organometallic complexes onto a given support, via surface organometallic chemistry (SOMC). In such cases, the immobilization of (transition) metal centres onto an inorganic support affords single-site catalysts with precise tuning of the coordination sphere and thus target-specific catalytic reactivity. In this context, the precise characterization of the surface sites by several spectroscopic techniques in parallel is of paramount importance. Solid-state NMR, in particular for half-integer quadrupolar nuclei, is a method that has increased its scope in the field of catalysis, especially due to recent methodological breakthroughs, occasionally combined with DFT calculations. In this tutorial review, we provide an overview of the most robust and efficient NMR experiments for half-integer quadrupolar nuclei, from simple one-dimensional acquisition under static and MAS conditions up to high-resolution and heteronuclear correlation two-dimensional spectra, as illustrated by selected examples.

Preparation of monopodal and bipodal aluminum surface species by selective protonolysis of highly reactive [AlH3(NMe2Et)] on silica.

The synthesis and characterization of silica-grafted monopodal and bipodal aluminum hydrides has been achieved starting from 200 °C- and 700 °C-annealed silica and [AlH3(NMe2Et)]. The mechanism by which aluminum trishydride reacts with isolated and vicinal silanols, assisted by the amine, has been investigated computationally at the ωB97XD-DFT level.

A new approach for the preparation of well-defined Rh and Pt nanoparticles stabilized by phosphine-functionalized silica for selective hydrogenation reactions.

In this work, a new methodology for the synthesis of well-defined metallic nanoparticles supported on silica is described. This methodology is based on the surface control provided by SOMC. The nanoparticles are formed via the organometallic approach and are catalytically active in the hydrogenation of p-xylene, 3-hexyne, 4-phenyl-2 butanone, benzaldehyde, and furfural.

17O MAS NMR studies of oxo-based olefin metathesis catalysts: a critical assessment of signal enhancement methods.

The DFS enhancement method as applied to 17O MAS NMR was critically assessed, first on NaPO3, a simple binary glass system, and in a second step, on a series of catalysis-related organometallic molecules and materials. The robustness of DFS was investigated for the wide range of anisotropic parameters (quadrupolar coupling and chemical shift anisotropy) encountered in these samples. Emphasis has been put on the variation of signal enhancements with respect to the DFS final sweep frequency, pulse amplitude and pulse duration, while line shape distortion issues were also addressed. Finally, the robustness of DFS enhancement of the 17O MAS NMR signal is shown through its successful application to silica-supported olefin metathesis catalysts.

Non-oxidative coupling of methane catalysed by supported tungsten hydride onto alumina and silica-alumina in classical and H2 permeable membrane fixed-bed reactors.

Non-oxidative coupling of methane with high selectivity into ethane (>99% among hydrocarbon) in a classical fixed-bed reactor catalysed by SiO(2)-Al(2)O(3) or gamma-Al(2)O(3) supported tungsten hydride is presented. Continuous hydrogen separation, using a Pd-Ag membrane in a fixed-bed reactor, led to methane coupling far beyond the thermodynamic equilibrium conversion.

[Fever and infectious complications in patient with lung cancer]. / Fièvre et complications infectieuses chez un patient porteur d'un cancer bronchique.

The respiratory infections are very frequent during lung cancer. Their diagnosis is often difficult because of the various etiologies (cancer, chemotherapy, radiotherapy) and this complexity can make discuss a preliminary bronchial exploration before any therapeutics. When it is about a located infection, germs in cause are often the same that in the community respiratory infections, in particular bacilli Gram negative, and it is thus logical to treat by the penicillin A. In front of an interstitial syndrome, it is necessary to evoke the opportunist infections, which are increasing in patients with cancer because of the multimodality therapeutic and the elongation of the survival. The neutropenic patient must be distinguished because of its specificities. The pulmonary infections lead to an important mortality. According to the patient (advanced age, underlying chronic obstructive pulmonary disease [COPD]) and to the treatment (chemotherapy, pneumonectomy), prevention must be discussed as the pneumococcal and Haemophilus influenzae vaccination.

Dinitrogen dissociation on an isolated surface tantalum atom.

Both industrial and biochemical ammonia syntheses are thought to rely on the cooperation of multiple metals in breaking the strong triple bond of dinitrogen. Such multimetallic cooperation for dinitrogen cleavage is also the general rule for dinitrogen reductive cleavage with molecular systems and surfaces. We have observed cleavage of dinitrogen at 250 degrees C and atmospheric pressure by dihydrogen on isolated silica surface-supported tantalum(III) and tantalum(V) hydride centers [(identical with Si-O)2Ta(III)-H] and [(identical with Si-O)2Ta(V)H3], leading to the Ta(V) amido imido product [(identical with SiO)2Ta(=NH)(NH2)]: We assigned the product structure based on extensive characterization by infrared and solid-state nuclear magnetic resonance spectroscopy, isotopic labeling studies, and supporting data from x-ray absorption and theoretical simulations. Reaction intermediates revealed by in situ monitoring of the reaction with infrared spectroscopy support a mechanism highly distinct from those previously observed in enzymatic, organometallic, and heterogeneous N2 activating systems.

Psychogenic nonepileptic seizures.

Psychogenic nonepileptic seizures are episodes of movement, sensation, or behaviors that are similar to epileptic seizures but do not have a neurologic origin; rather, they are somatic manifestations of psychologic distress. Patients with psychogenic nonepileptic seizures frequently are misdiagnosed and treated for epilepsy. Video-electroencephalography monitoring is preferred for diagnosis. From 5 to 10 percent of outpatient epilepsy patients and 20 to 40 percent of inpatient epilepsy patients have psychogenic nonepileptic seizures. These patients inevitably have comorbid psychiatric illnesses, most commonly depression, posttraumatic stress disorder, other dissociative and somatoform disorders, and personality pathology, especially borderline personality type. Many patients have a history of sexual or physical abuse. Between 75 and 85 percent of patients with psychogenic nonepileptic seizures are women. Psychogenic nonepileptic seizures typically begin in young adulthood. Treatment involves discontinuation of antiepileptic drugs in patients without concurrent epilepsy and referral for appropriate psychiatric care. More studies are needed to determine the best treatment modalities.

An integrated neuropsychiatric approach to diagnosis and management of patients with epileptic seizures.

In patients who present to neurology settings with history of epileptic seizures, psychiatric disorders may be the sole manifestation of apparent neurologic symptoms, or they may coexist. Current challenges for clinicians include distinguishing between two disorders and making the correct diagnoses, interpreting test results, and (co-) managing the disorder(s). Our goal is to provide the clinician with an integrated neuropsychiatric approach for the triage, assessment (history, screening tools, examination, diagnostic tests), and treatment (neurologic and/or psychiatric) of these challenging patients. In particular, use of schemata, tables, and algorithms will offer step-by-step approaches and guidelines for the clinician. Recommendations are made for the indications for psychiatric consultation, and co-management is recommended for patients with emergencies, those who fail routine psychiatric treatments, and those with complex presentations or multiple comorbid conditions.

Clinical experience of levetiracetam monotherapy for adults with epilepsy: 1-year follow-up study.

We identified 46 patients with a history of partial seizures, with and without secondarily generalization, who received levetiracetam (LEV) (Keppra) monotherapy. Patients began LEV either as first line therapy (n=11) or were converted to LEV monotherapy (n=35) after failing prior antiepileptic medications (AEDs). Patients were followed up to 12 months after LEV started. The majority of these patients were able to continue on LEV and a small number of patients discontinued LEV secondary to lack of efficacy. One third of the non-seizure free group at 6 months of follow-up had worse seizure control at 12 months and two thirds had the same or better seizure control. Our 1-year follow-up data of LEV as monotherapy suggests that LEV can be effective and well tolerated in adults with either new or difficult to control epilepsy. A prospective, large, long-term double-blind study is needed to confirm this finding.

Improvement in seizure control and quality of life in medically refractory epilepsy patients converted from polypharmacy to monotherapy.

In a retrospective chart review, we identified 35 patients with medically refractory epilepsy (MRE) who had been converted from polypharmacy to monotherapy and maintained on monotherapy for at least 12 months. None of the 35 patients had worsening of their seizure frequency after the conversion to monotherapy. Fourteen of the 35 patients (40%) became seizure-free. Nine of 35 patients (26%) had a 50% reduction in seizure frequency. Five of 35 patients (14%) had a 75% reduction in seizure frequency. Twenty-eight (80%) of 35 patients participated in a quality-of-life questionnaire. Quality of life was rated as better on monotherapy as compared with polypharmacy in a number of domains: memory loss, concern over medication long-term effects, difficulty in taking the medications, trouble with leisure time activities, and overall state of health. This improvement reached statistical significance. Conversion to monotherapy in patients with MRE may be successful in achieving a reduction in seizure frequency and an improvement in quality-of-life parameters. A prospective, randomized trial is necessary to validate these findings.

Psychogenic nonepileptic seizures are associated with an increased risk of obesity.

Psychogenic nonepileptic seizures (NES) are somatic manifestations of psychological distress. There is some evidence that weight problems are more common in patients with psychiatric illness. We have observed that patients admitted for video-EEG monitoring who we diagnosed with NES commonly have a larger body habitus than patients with epilepsy. The goal of this study was to test our hypothesis that there was a significant difference in body mass index (BMI) in patients with nonepileptic seizures compared with their epileptic counterparts. We compared the BMIs of 46 NES patients and 46 age- and gender-matched epileptic controls and found that the NES patients had significantly higher BMIs (30.5 vs 26.1, P=0.006) than controls. This remained true after controlling for weight-gain properties of antiepileptic drugs. These results are compared with the prevalence of overweight and obesity in the general population. Possible explanations of the findings and limitations of the study are discussed.

Video-EEG telemetry can be a crucial tool for neurologists experienced in epilepsy when diagnosing seizure disorders.

We retrospectively reviewed the charts of 121 patients consecutively admitted to our epilepsy-monitoring unit (VET) during the period of 01 July 2001 to 31 December 2002. We excluded patients with a confirmed diagnosis of epilepsy who were admitted for invasive pre-surgical monitoring. Medical records were reviewed to collect demographic and clinical information that lead to the initial referral for VET by neurologists with expertise in epilepsy or by an epileptologist. We identified 29 patients (24%), whose diagnosis changed after VET. Their seizure duration ranged from 1 to 46 years. A diagnosis of epileptic seizures (ES) was made in four of the patients who were initially felt to have nonepileptic seizures (NES). The diagnosis of NES was made in 22 patients who were initially felt to have ES. All of these 29 patients had failed at least two or more antiepileptic drugs (AEDs). A misclassification of epilepsy syndrome was found in three patients. Eleven of the NES patients had risk factors that would increase the likelihood of ES, including significant head injury (n=6), febrile seizures (n=2), meningioencephalitis (n=2), and tumours (n=1). Four of these 11 patients had abnormal interictal EEGs. We conclude that VET is crucial in establishing a diagnosis in patients with seizures. Without VET, patients can be misclassified or receive ineffective treatment, even when being treated by specialists in epilepsy. Thus, VET, can help facilitate the most appropriate type of therapy in difficult to control patients.

Levetiracetam monotherapy for elderly patients with epilepsy.

We retrospectively identified 14 elderly patients with a history of partial seizures who received levetiracetam (LEV) monotherapy. Patients began LEV either as first line therapy (n=5) or were converted to LEV monotherapy (n=9) after failing prior antiepileptic medications (AEDs). Thirteen patients continued on LEV monotherapy for at least 6 months. One patient was lost to follow-up. Eight patients (61.5%) became seizure free. Four patients who began LEV as a first line therapy became seizure free, whereas the remaining four patients who converted to LEV after they failed their previous AEDs became seizure free. Four patients (30.7%) had more than a 50% seizure reduction of seizures. Only one patient had no significant change in seizure frequency after started on LEV. The total dosages used to control seizures were 500-3000 mg/day, (mean 1839.2 mg/day). LEV monotherapy can be effective and well tolerated in this group of patients. A prospective, larger, double blind monotherapy study is needed to confirm this finding.

Psychogenic nonepileptic seizures: acute change in event frequency after presentation of the diagnosis.

Seizure frequency during inpatient video EEG monitoring was examined before and after the diagnosis of psychogenic nonepileptic seizures (PNES) was presented to patients (N=22). A control group of 10 patients with epileptic seizures (ES) were also followed from pre- to postdiagnosis. The number of PNES or ES within the 24-hour period prior to diagnosis was compared with the number of events that occurred within the 24-hour period after presentation of the diagnosis. Findings indicate that patients with PNES had a significant decrease in the frequency of events after diagnosis, while those with ES showed no change in event frequency after diagnosis. Eighteen of twenty-two patients with PNES had no further events during an acute follow-up period. Results suggest that providing patients with a diagnosis of PNES appears to reduce the acute frequency of PNES and may be an important first step in the long-term remediation of PNES. Long-term follow-up is needed to determine if such feedback alters the course of the disorder.

Lateralising value of ictal features in partial seizures: effect on postsurgical outcome.

We reviewed the videotapes of 49 consecutive patients with a history of medically refractory temporal lobe epilepsy for the presence and laterality of unilateral hand posturing (UHP), unilateral hand automatism (UHA), non-forced head turning (HT), and post-ictal dysphasia (PID). All of these patients underwent temporal resections with follow-up for more than 2 years after the surgery. We examined the correlation of consistency, frequency, and laterality of each of these signs on the postsurgical outcomes. The distribution of these signs was not significantly different between patients with Engel class 1 versus Engel class 2-4. The consistency and laterality of these signs do not correlate with postsurgical outcomes.

Levetiracetam monotherapy for newly diagnosed epilepsy patients.

We retrospectively reviewed the charts of all of our patients with a history of partial seizures, with and without secondarily generalisation, who received levetiracetam (LEV; Keppra) for treatment of their seizures during the years 2000-2002. Forty-five patients were identified, 13 of whom began LEV as first line therapy. Eleven patients continued on LEV for at least 6 months; six of whom became seizure free and five had >50% reduction in their seizures. The remaining two patients discontinued LEV because of adverse effects. LEV monotherapy can be effective and well tolerated in adults with new onset seizures. A prospective, large, double-blind monotherapy study for newly diagnosed patients is needed to confirm this finding.

fMRI in patients implanted with a vagal nerve stimulator.

OBJECTIVE: To demonstrate the feasibility and safety of using functional magnetic resonance imaging (fMRI) to determine the blood oxygen level dependent changes (BOLD) in patients undergoing vagal nerve stimulation (VNS) for the treatment of epilepsy. METHODS: Four patients with an implanted vagus nerve stimulator had fMRI images acquired during several cycles of intermittent VNS. Blood oxygen level dependent changes were detected. These regions were then superimposed upon the patients' structural MR images. RESULTS: Patients undergoing VNS tolerated fMRI without difficulty. No complications with the implanted stimulators were encountered. Areas of activation were noted in several cortical regions, including frontal, temporal, parietal, and occipital cortices. CONCLUSION: Our study in four patients shows fMRI can be performed safely in patients with an implanted vagal nerve stimulator. The successful use of fMRI during VNS offers potential advantages over PET imaging by allowing rapid image acquisition and the ability to repeatedly study patients over time. Our preliminary results differ from previous PET or SPECT studies in failing to detect changes in subcortical areas. This finding could be due to the smaller n in this study compared with the other studies.

Levetiracetam monotherapy for adults with localization-related epilepsy.

We identified 37 patients with a history of partial seizures, with and without secondarily generalization, who received levetiracetam (LEV) (Keppra) monotherapy. Patients began LEV either as first line therapy (n=9) or were converted to LEV monotherapy (n=28) after failing prior antiepileptic medications (AEDs). Thirty-four patients continued on LEV for at least six months; of these, 13 patients became seizure free and 15 patients had >50% reduction in their seizures. Three patients discontinued LEV because of adverse effects. LEV monotherapy can be effective and well tolerated in adults with new onset and difficult-to-control partial epilepsy. A prospective, large, double blind monotherapy study is needed to confirm this finding.