The neural correlates of road sign knowledge and route learning in semantic dementia and Alzheimer's disease.

BACKGROUND: Although there is a growing body of research on driving and Alzheimer's disease (AD), focal dementias have been understudied. Moreover, driving has never been explored in semantic dementia (SD). METHODS: An experimental battery exploring road sign knowledge and route learning was applied to patients with SD and AD selected in the early-moderate stage of disease and to a group of healthy participants. Neuropsychological data were correlated to cerebral hypometabolism distribution, investigated by means of positron emission tomography. RESULTS: The two dementias showed opposite profiles. Patients with SD showed poor road sign knowledge and normal performance in route learning. By contrast, patients with AD showed low performance in route learning test with preservation of semantic knowledge of road signs. In SD, there was a correlation of semantic knowledge impairment with hypometabolism in the left temporolateral cortex. No correlation between the AD region of interests (ROIs) and the relevant behavioural indices was found, while in the whole-brain analysis there was a significant correlation between route learning and the superior frontal gyrus. DISCUSSION AND CONCLUSIONS: For the first time, driving skills were explored in SD, and it is showed a differential profile from the one detected in AD. We demonstrate that the left anterior temporal cortex is implicated in road sign knowledge, while a distributed cortical network, including the frontal cortex, is likely to process route learning.

Efficient O-trimethylsilylation of alcohols and phenols with trimethylsilyl azide catalyzed by tetrabutylammonium bromide under neat conditions.

A very efficient procedure for the trimethylsilylation of a wide variety of alcohols, including primary, allylic, benzylic, secondary, hindered secondary, tertiary, and phenols is reported. The reactions were carried out under neat conditions with trimethylsilyl azide (TMSN(3)) and, when necessary, in the presence of a catalytic amount (20 mol %) of tetrabutylammonium bromide (TBABr) at 30 or 70 degrees C. Under catalytic conditions, the yields of the corresponding trimethylsilyl ethers were greater than 91%. This procedure also allows the selective protection of primary and secondary alcohols in the presence of tertiary ones.

Bromolysis and iodolysis of alpha,beta-epoxycarboxylic acids in water catalyzed by indium halides.

The ring opening of alpha,beta-epoxycarboxylic acids by bromide and iodide ions has been efficiently carried out in water in high regio- and stereoselective fashion. The iodolysis of trans-beta-monoalkylated epoxycarboxylic acids at pH 4.0 was completely alpha-regioselective and anti diastereoselective. The InCl(3)-catalyzed iodolysis of a variety of alpha,beta-epoxycarboxylic acids at pH 1.5 gave the corresponding anti beta-iodohydrins in 88-95% yields. The one-pot synthesis of the alpha- and beta-hydroxyhexanoic acids, starting from the corresponding alpha,beta-epoxycarboxylic acid 1a by iodolysis followed by reduction of the resulting iodohydrins 4a and 4b by NaBH(4)-InCl(3) in water, has been performed.

[4 + 2] cycloadditions of nitroalkenes in water. Highly asymmetric synthesis of functionalized nitronates.

The [4 + 2] cycloadditions of (E)-2-aryl-1-cyano-1-nitroalkenes 1 with achiral and enantiopure vinyl ethers 2 and 3 carried out in sole water are reported. These reactions occur in a heterogeneous phase under mild conditions and are fast and highly stereoselective. By using (-)-N,N-dicyclohexyl-(1S)-isoborneol-10-sulfonamide as a chiral auxiliary, the cycloadditions are totally asymmetric. The face selectivity is discussed in terms of the shape of the chiral auxiliary and the reactive conformation of vinyl ether.

Lewis-acid catalyzed organic reactions in water. The case of AlCl(3), TiCl(4), and SnCl(4) believed to be unusable in aqueous medium.

Classical Lewis acids such as AlCl(3), TiCl(4), and SnCl(4), believed to be unusable as catalysts in aqueous medium, efficiently catalyzed regio- and stereoselective azidolysis and iodolysis of alpha,beta-epoxycarboxylic acids in water at pH 4.0 and 1.5, respectively. The concept of water-tolerant metal-salt is reexamined in direct relationship to the aqua ion hydrolysis constant.

Azidolysis of alpha,beta-epoxycarboxylic acids. A water-promoted process efficiently catalyzed by indium trichloride at pH 4.0.

The catalytic efficiency of InCl(3), Yb(OTf)(3), and Sc(OTf)(3) in the azidolysis of alpha,beta-epoxycarboxylic acids has been studied in water and in organic solvents, for comparison using NaN(3) and Me(3)SiN(3) as the source of the azido group. In water, the catalytic effectiveness of these metal salts strongly depends on the pH of the aqueous medium and on the type of Lewis acid catalyst. In water their catalytic activity is mostly due to the corresponding aqua ion species, the concentration of which becomes significant when the pH of the aqueous medium is below the corresponding pK(1,1) hydrolysis constant. The process is more efficient in water than in organic solvents. At pH 4.0, InCl(3) is a far better catalyst than Yb(OTf)(3) or Sc(OTf)(3) and allows the highly regio- and diasteroselective preparation of beta-azido-alpha-hydroxycarboxylic acids, which can be isolated in pure form in very high yields.

Complementary role of whole body scan and serum thyroglobulin determination in the follow-up of differentiated thyroid carcinoma.

In 233 patients with differentiated thyroid carcinoma previously treated by total thyroidectomy supplemented, when necessary, with a therapeutic dose of 131I, serum thyroglobulin determinations and whole body scans were simultaneously performed. 82 of the 233 showed local or distant metastases: they were detected by both tests only in 36 cases. In 43 patients thyroglobulin was positive but without pathological concentrations of 131I at whole body scan were observed. The remaining 3 cases were detected on the basis of the positive whole body scan only, without increase in the circulating thyroglobulin. These results suggest that caution should be taken when considering thyroglobulin determination as possible substitutive test of whole body scan in the follow-up of differentiated thyroid carcinoma. However, for optimal sensitivity and reliability the complementary role of the two tests is stressed.