Bis(alkyl) scandium and yttrium complexes coordinated by an amidopyridinate ligand: synthesis, characterization and catalytic performance in isoprene polymerization, hydroelementation and carbon dioxide hydrosilylation.

New neutral bis(alkyl) Sc and Y complexes [N,Npy,N-]Ln(CH2SiMe3)2(THF)n [n = 0, Ln = Sc (1Sc), Y (1Y); n = 1, Ln = Y (1YTHF)] stabilized by a tridentate monoanionic amidopyridinate ligand were straightforwardly prepared by alkane elimination, upon mixing ligand [N,Npy,N-]H and metal precursor Ln(CH2SiMe3)3(THF)2 in toluene at 0 °C. Depending on the work-up conditions, yttrium bis(alkyl)s were isolated as either a pentacoordinate Lewis base free complex [N,Npy,N-]Y(CH2SiMe3)2 (1Y) or as a hexacoordinate THF adduct [N,Npy,N-]Y(CH2SiMe3)2THF (1YTHF). For the smaller Sc ion the only solvent-free complex [N,Npy,N-]Y(CH2SiMe3)2 (1Sc) was isolated as a pentacoordinate species irrespective of the reaction/work-up/crystallization conditions applied. Complexes 1Ln (Ln = Y, Sc) and 1YTHF were scrutinized as pre-catalysts in ternary catalytic systems Ln/borate/AliBu3 (borate = [HNMe2Ph][B(C6F5)4] or [Ph3C][B(C6F5)4]), applied to isoprene (IP) polymerization, providing moderate activity albeit high selectivity with predominant formation of 1,4-cis polyisoprene (up to 99%). The same complexes proved to be effcient catalysts also for the intermolecular hydrolelementation of styrene with various EH sustrates (pyrrolidine, morpholine, Ph2PH, PhPH2, PhSH) affording linear anti-Markovnikov addition products exclusively. After a preliminary activation by B(C6F5)3, selected bis(alkyl) complexes from this series have been finally used as valuable pre-catalysts for the CO2 hydrosylilation to CH4 in the presence of organosilanes as reducing agents (PhMe2SiH, PhSiH3, Et2MeSiH).

Use of organolanthanides in the catalytic intermolecular hydrophosphination and hydroamination of multiple C-C bonds.

This review covers recent achievements in the intermolecular hydrophosphination and hydroamination of alkenes, dienes and alkynes catalyzed by organolanthanides.

[Heterogeneity of chromosomal abnormalities in cultured melanoma cells of human skin].

Karyotypes of 9 malignant melanoma patients has been described. It is ascertained that most often the damage is observed in chromosomes 1, 6, 7, 9 and 17, which is consistent with the data in the literature. Besides chromosomes 5 and 13 are also often involved in different rearrangements. Recurring aberrations are not discovered. Any correlation between survival and non-recurrent chromosomal aberrations is not discovered.

[Value of combined conventional and contrast enhanced sonography in the evaluation of hepatic disorders]. / Apport de l'échographie de contraste et échographie conventionnelle simultanée en pathologie hépatique.

PURPOSE: To assess the value of combined conventional and contrast-material enhanced sonography for the characterization of focal liver lesions. MATERIALS AND METHODS: Simultaneous imaging with grey scale and contrast enhanced US was performed in 90 patients following Levovist injection (Schering, Berlin, Germany) using the "Agent Detection Imaging" method (ADI, Siemens-Acuson, Mountain View, USA). US scanning was performed at least 4 minutes after contrast injection with review of both grayscale and contrast enhanced modes. Results for detection and characterization of lesions were compared to the selected gold standard imaging modality (CT or MRI). RESULTS: Final diagnoses included: 20 normal examinations, 41 patients with metastases, 6 patients with hepatocellular carcinoma, 13 patients with hemangioma, 6 patients with other benign lesions, 4 patients with cysts and 6 patients with two types of lesions. Delayed phase contrast enhanced US allowed diagnosis of all lesions except for one metastasis and all hepatocellular carcinomas. While the diagnosis of hepatoma could not be confirmed, the features suggested a malignant etiology. For 7 patients with metastases, more lesions were detected at ADI (4.9 lesions) than at conventional US (1.1 lesion). For 3 patients, CT showed more lesions than ADI US (3.3 versus 1.6 lesions). The accuracy of ADI US for differentiating between benign and malignant lesions was 98.7% compared to 49.6% for conventional US (p<0.001). The total number of lesions detected at ADI US was higher (p<0.01) than at conventional US and not significantly different from that obtained by the gold standard reference methods. Complete characterization was achieved in 92.2% of cases with ADI US compared to 59.2% with conventional US (p<0.001). CONCLUSION: Contrast-material enhanced US combined with conventional US markedly improves the diagnostic accuracy of US in terms of lesion detection and characterization.

[Contrast ultrasound imaging in liver disease]. / Echographie de contraste et affections hépatiques.

The recent introduction of high-end ultrasound equipments combined with the introduction of contrast agents provides marked improvements in liver imaging for the detection and the characterization of focal lesions. Previous imaging methods were based on high acoustic power and demonstrated improved detection of focal liver lesions. However, good and reliable results were difficult to achieve due to limited number of sweeps, as most of the microbubbles were destroyed within one pass. Non linear imaging methods at low acoustic power allowed great advances in the characterization by limiting signal from background tissue as well as agent collapse allowing continuous imaging starting from the time of contrast injection until complete disappearance of the agent. Contrast-enhanced imaging of the liver follows conventional sonography performed with high standards for detection and localization of lesions using multiple sweeps. Then targeted acquisition is performed for specific lesion characterization after a second contrast injection. Interpretation is based on the presence or not of microbubbles within the lesion (hyper-, hypo- or isosignal) and the delay from injection (arterial, portal or parenchymal or late phase). A well-recognized semiology is reported in this paper. Based on these criteria, sensitivity and specificity are close to those reported with other modalities with accuracy 85-95% for focal liver lesions and 75% for hepatocellular carcinomas. Those results markedly improve ultrasound accuracy compared to conventional sonography, and so put contrast-enhanced sonography among recommended non-invasive imaging methods for focal liver lesions with changes in diagnostic strategy.

[Value of sonography in the diagnosis and follow-up of patients with cryptogenic inflammatory bowel diseases in current practice: review of a 10-year experience in a community hospital]. / Intérêt de l'échographie dans le diagnostic et le suivi des maladies inflammatoires cryptogénétiques de l'intestin en pratique courante. A propos de dix années d'expérience d'un service d'imagerie générale hospitalier privé.

Inflammatory bowel diseases (IBD) are chronic inflammatory diseases of the bowel that are of unknown etiology. These diseases either progress with intermittent flare-ups interrupted by periods of remission or on a chronic active progressive mode. IBDs include Crohn disease (CD) and ulcerative colitis (UC). Clinical and imaging diagnosis often is challenging, hence explaining the frequent time delay between onset of disease and initiation of therapy. Clinical evaluation is characterized by three consecutive steps: consider a diagnosis of IBD; exclude other causes of inflammatory bowel disease; differentiate CD from UC since a definitive curative surgical treatment is available for UC. US is non-invasive, widely available, easy to perform, and relatively inexpensive and thus represents a significant advance in the evaluation of these three steps. The role of US in the evaluation of patients with suspected IBD will be reviewed.

[Quantification of hepatic arterial and portal venous flow using ultrasound contrast agents for early detection of liver metastases of colorectal cancers]. / Quantification des débits hépatiques artériel et porte à l'aide des produits de contraste ultrasonores: application au diagnostic précoce des métastases hépatiques des cancers colorectaux.

PURPOSE: To quantify liver blood flow using US contrast agents and to evaluate arterial and portal changes in control patients and patients with liver metastases. MATERIALS AND METHODS: Twenty eight patients were included in this study, 8 controls (M0) and 20 patients with liver metastases from colon carcinoma (M+). Hepatic blood flow from hepatic artery and portal vein were determined using quantification of enhancement after contrast injection using Power Doppler US. The ratio of enhancement rise from artery and vein allows calculation of Contrast Enhanced Doppler Perfusion Index (CEDPI) as previously described for Doppler Perfusion Index (DPI). RESULTS: A significant difference was noted for CEDPI between controls (0.49 +/- 0.07) and liver with metastases (0.70 +/- 0.12). CONCLUSION: This functional method of evaluation of liver blood flow was easy to perform, and would be valuable for early detection of overt micro-metastases before anatomical changes observed by conventional imaging. This is helpful for accurate staging of colon carcinoma.

Quantum Number Dependence of Lineshift Coefficients Induced by Collisions with Noble Gas Perturbers in the nu(3) Band of NO(2).

To complete our study concerning lineshift in the rovibrational spectrum of (14)N(16)O(2), a pulse-driven three-channel lead salt diode laser spectrometer was applied to record high-resolution spectra at room temperature in the 6.2-µm region corresponding to the nu(3) band at low NO(2) concentrations. The shift was studied for collisions with the noble gases He, Ne, Ar, Kr, and Xe. This paper extends our recently published data in order to analyze the quantum number dependence of the shift effect more precisely. Therefore, in this paper, additionally eight unresolved NO(2) doublets covering an enlarged quantum number range (10

Determination of the Line-Shift and Line-Broadening Coefficients in the nu(3) Band of ()NO(2) Perturbed by ()O(2), N(2), H(2), D(2), and CO(2).

A high-resolution three-channel diode-laser spectrometer was used to record a large number of spectra with (14)N(16)O(2) and foreign gas pressures ranging from 0.1 to 0.4 and 20 to 150 Torr, respectively, at room temperature. The 6.2-µm region corresponding to the nu(3) band of NO(2) was analyzed and the broadening and shift coefficients were derived in the case of collisions between NO(2) and H(2), D(2), O(2), N(2), CO(2), and SO(2) for 13 lines with 18

Line Shift Investigations for Different Isotopomers of Carbon Monoxide.

Line shift coefficients for five lines of five different isotopomers in the fundamental band of CO in the spectral region near 2058 cm-1 were measured using a three channel lead salt diode laser spectrometer. The study includes the lines P(3) of 13C17O, R(3) of 13C18O, P(9) of 12C18O, P(10) of 13C16O, and P(21) of 12C16O, and covers collisions with N2, O2, H2, D2, He, Ne, Ar, Kr, and Xe. Line shifts of the isotopomers 13C16O, 12C18O, 13C18O, and 13C17O were determined for the first time. Within the experimental uncertainty no significant dependence of the shift effect on the isotopomer was found. The R-branch line under study shows a smaller line shift coefficient than a P-branch line with a similar rotational quantum number. With increasing mass of the noble gas perturber the absolute size of the shift coefficient increases. Moreover self- and nitrogen-broadening coefficients for the isotopomer lines were determined. Compared to previous measurements no significant deviations between different isotopomers were observed. Copyright 1998 Academic Press.