The protective role of endogenous n-3 polyunsaturated fatty acids in Tau Alzheimer's disease mouse model.

Objectives: The role of n-3 polyunsaturated fatty acid (PUFA) as the main docosahexaenoic acid (DHA) in Alzheimer's disease (AD) remains controversial. Our study aimed to provide detailed information about the role of endogenous n-3 PUFAs in AD.

Methods: Here, we generated a fat-1/tau transgenic mouse AD model by crossing female tau mice with male fat-1 mice to exclude confounding variables associated with the benefit of a DHA diet in these AD mice models.

Establishment and evaluation of four different types of patient-derived xenograft models.

Background: Patient-derived xenografts (PDX) have a biologically stable in tumor architecture, drug responsiveness, mutational status and global gene-expression patterns. Numerous PDX models have been established to date, however their thorough characterization regarding the tumor formation and rates of tumor growth in the established models remains a challenging task. Our study aimed to provide more detailed information for establishing the PDX models successfully and effectively.

Substantial genome synteny preservation among woody angiosperm species: comparative genomics of Chinese chestnut (Castanea mollissima) and plant reference genomes.

Background: Chinese chestnut (Castanea mollissima) has emerged as a model species for the Fagaceae family with extensive genomic resources including a physical map, a dense genetic map and quantitative trait loci (QTLs) for chestnut blight resistance. These resources enable comparative genomics analyses relative to model plants. We assessed the degree of conservation between the chestnut genome and other well annotated and assembled plant genomic sequences, focusing on the QTL regions of most interest to the chestnut breeding community.

Characterization of insulin degrading enzyme and other amyloid-β degrading proteases in human serum: a role in Alzheimer's disease?

Sporadic Alzheimer's disease (AD) patients have low amyloid-β peptide (Aβ) clearance in the central nervous system. The peripheral Aβ clearance may also be important but its role in AD remains unclear. We aimed to study the Aβ degrading proteases including insulin degrading enzyme (IDE), angiotensin converting enzyme (ACE) and others in blood.

Reactions of silyl-stabilised sulfur ylides with organoboranes: enantioselectivity, mechanism, and understanding.

The reaction of trimethylsilyl-substituted sulfonium ylides with organoboranes (Ph(3)B, Et(3)B) has been studied and although homologated products were obtained in good yield (after oxidation to the corresponding alcohols), the enantiomeric excesses were low with our camphor-based chiral sulfide (up to 40% ee, cf. corresponding phenyl-substituted sulfonium ylides gave >95% ee). Cross-over experiments were conducted to ascertain the nature of this difference in selectivity.

Asymmetric lithiation-substitution of amines involving rearrangement of borates.

Asymmetric lithiation of substituted benzylamines, N-Boc-pyrrolidine, or N-Boc-indoline using Beak's methodology was followed by electrophilic quench with trialkylboranes. The resulting borate intermediates rearrange with concomitant C-N bond breakage to give, after oxidation, chiral secondary alcohols with high enantioselectivity.

Asymmetric sulfur ylide reactions with boranes: scope and limitations, mechanism and understanding.

The reactions of aryl-stabilized sulfur ylides with organoboranes has been studied under a variety of conditions. At 5 or -78 degrees C, the reaction with Et3B gave a mixture of the first and second homologation products, but at -100 degrees C, only the first homologation product was obtained even with just 1.1 equiv of Et3B.

Is phenyl a good migrating group in the rearrangement of organoborates generated from sulfur ylides?

Calculations show that the unexpected low phenyl migratory aptitude observed in reactions of mixed alkyl-aryl boranes with benzylic sulfur ylides can be attributed to (1) a conformational issue, (2) the reduction of the usual neighbouring effect of the phenyl in the transition state by the benzylic nature of the migrating terminus, (3) steric hindrance suffered by the larger phenyl group migrating to the hindered migrating terminus and this despite (4) the increase in the barrier to alkyl migration by the presence of a 'non-migrating' phenyl on the boron atom.

Synthesis and applications of chiral organoboranes generated from sulfonium ylides.

The reactions of aryl-stabilized sulfonium ylides with trialkyl/triarylboranes have been investigated. Clean monohomologation of the boranes with only a small amount of the higher homologation products (<10%) was observed. The homologation products were isolated as the alcohols (treatment with H2O2/NaOH) and amines (treatment with NH2OSO3H).

Highly diastereoselective Simmons-Smith cyclopropanation of allylic amines.

[reaction: see text] Cyclopropanation of allylic tertiary amines using the Simmons-Smith reagent has been achieved by employing chelating groups in close proximity to the amine. The chelating groups promote cyclopropanation at the expense of N-ylide formation. Using pseudoephedrine as the chelating group, high diastereoselectivity is observed.

Tandem formation and [2,3] rearrangement of methylene ammonium ylides derived from amines and the Simmons-Smith reagent.

[reaction: see text] Zinc-complexed methylene ammonium ylides are formed from tertiary amines and the Simmons-Smith reagent. These stable entities can be activated with n-BuLi to allow reactions typical of ammonium ylides such as [2,3] rearrangements. In the case of oxazolidine 12, ylide formation, activation, and subsequent [2,3] rearrangement was highly efficient and occurred with very high diastereoselectivity.