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Stereoselective conversion of a selenoglycoside to a beta-bromoglycoside in the absence of a glycosyl acceptor followed by the coupling with another selenoglycoside affords the corresponding glycosylated selenoglycoside, which could be directly used for the next glycosylation. The iteration of this sequence allows the synthesis of a variety of oligosaccharides including an elicitor active heptasaccharide. [reaction: see text]

A novel methodology for the deprotonation of a methyl group on silicon has been developed. This newly developed alpha-lithiation protocol is based on the intramolecular pyridyl group coordination to stabilize the alpha-silyl carbanion together with the inherent silicon alpha effect. It was found that the deprotonation (t-BuLi/Et(2)O/-78 degrees C) occurs with 2-pyridyltrimethylsilane but not with other related silanes such as phenyltrimethylsilane, 3-pyridyltrimethylsilane, and 4-pyridyltrimethylsilane. It seems that this deprotonation proceeded through the agency of the complex-induced proximity effect (CIPE) of a 2-pyridyl group on silicon. (1)H NMR analysis of (2-pyridyldimethylsilyl)methyllithium revealed the intramolecular coordination of a pyridyl group to lithium. (2-Pyridyldimethylsilyl)methyllithium was found to react with chlorosilanes, hydrosilanes, chlorostannanes, bromine, iodine, organic bromides, aldehydes, and ketones in good to excellent yields. The resultant adducts were further oxidized with H(2)O(2)/KF to give the corresponding alcohols in excellent yields. Thus, this two-step transformation provides an efficient method for the nucleophilic hydroxymethylation.

Purpose: The purpose of this study was to ascertain the usefulness of MR imaging in the diagnosis of nodal metastasis of papillary thyroid carcinoma and to establish the most indicative MR criteria of metastasis., Methods: Pathologic records and MR images in 50 patients with papillary thyroid carcinoma were reviewed. Each neck was divided into four nodal levels, so that 200 nodal levels were assessed in all. The maximum of the minimum transverse diameters of the lymph nodes on each nodal level measured on MR images and the certainty of metastasis as determined by a head and neck radiologist on the basis of morphologic aspects were compared with the pathologic findings by using receiver operating characteristic curves. The presence or absence of cystic nodes on each nodal level was also evaluated., Results: Metastasis was found on 87 (44%) of the nodal levels in 34 (68%) of the patients. A cystic node was identified on 33 (17%) of the nodal levels in 13 (26%) of the patients and was seen only on positive nodal levels. Morphologic diagnosis by the radiologist was better than that obtained by measurement. With the combined criteria of a cystic node or a node of 13 mm or more for the maximum of the minimum transverse diameters, specificity was 100% with an 82% accuracy and always indicated metastasis (100% positive predictive value). However, 41% of the metastatic nodes were missed with this criterion (59% sensitivity)., Conclusion: MR imaging was useful for diagnosing metastatic nodes; a nodal diameter threshold of 13 mm or the presence of a cystic node strongly indicated metastasis from papillary thyroid carcinoma.

An accurate and time-saving method for the determination of norepinephrine in human plasma is described. The whole device focused on an improvement in the pretreatment. One ml of human plasma was applied to a boric acid gel column without deproteinization and pH adjustment, and norepinephrine was eluted with 2 ml of a 1.3 M acetic acid in methanol solution. The pentafluoropropionic derivative of norepinephrine was analysed by gas chromatography mass spectrometry using deuterated norepinephrine as an internal standard. The level of plasma norepinephrine in healthy subjects at recumbency was 297 +/- 95 pg ml-1 (mean +/- SD). The lower limit of sensitivity was 25 pg ml-1 of norepinephrine in plasma.