Diffusion tensor magnetic resonance imaging of the normal breast

Purpose

The objective of this study was to evaluate diffusion anisotropy of the breast parenchyma and assess the range and repeatability of diffusion tensor imaging (DTI) parameters in normal breast tissue.

Materials and Methods

The study was approved by our institutional review board and included 12 healthy females (median age, 36 years). Diffusion tensor imaging was performed at 1.5 T using a diffusion-weighted echo planar imaging sequence. Diffusion tensor imaging parameters including tensor eigenvalues (λ₁, λ₂, λ₃), fractional anisotropy (FA) and apparent diffusion coefficient (ADC) were measured for anterior, central and posterior breast regions.

Results

Mean normal breast DTI measures were λ₁=2.51×10⁻³ mm²/s, λ₂=1.89×10⁻³ mm²/s, λ₃=1.39×10⁻³ mm²/s, ADC=1.95±0.24×10⁻³ mm²/s and FA=0.29±0.05 for b=600 s/mm². Significant regional differences were observed for both FA and ADC (P<.05), with higher ADC in the central breast and higher FA in the posterior breast. Comparison of DTI values calculated using b=0, 600 s/mm² vs. b=0, 1000 s/mm², showed significant differences in ADC (P<.001), but not FA. Repeatability assessment produced within-subject coefficient of variations of 4.5% for ADC and 11.4% for FA measures.

Conclusion

This study demonstrates anisotropy of water diffusion in normal breast tissue and establishes a normative range of breast FA values. Attention to the influence of breast region and b value on breast DTI measurements may be important for clinical interpretation and standardization of techniques.     

Asymmetric synthesis of novel spirocycles via a chiral phosphoric acid catalyzed desymmetrization

A straightforward method for the asymmetric preparation of novel lactone and lactam spirocycles is described. An initial desymmetrization via a chiral Brønsted acid yields enantioenriched lactones which readily undergo a second cyclization to give the desired spirocycle.     

Methods for engineering therapeutic peptides

This review discussed recent advancements related to therapeutic peptide engineering.     

Asymmetric, organocatalytic, three-step synthesis of gamma-hydroxy-(E)-alpha,beta-unsaturated sulfones and esters

Efficient and enantiocontrolled synthesis of gamma-hydroxy-alpha,beta-unsaturated sulfones and esters are reported through the reaction of enantioenriched alpha-selenyl aldehydes with EWG-stabilized carbanions and then a one-pot selenide oxidation, in situ epoxide formation, and final in situ epoxide opening.     

Synthesis and anti-HIV activity of 5-haloethynyl and 5-(1,2-dihalo)vinyl analogues of AZT and FLT

In this paper, we report the synthesis of hitherto unknown 5-haloethynyl and 5-(1,2-dihalo)vinyluracil nucleoside analogues of the anti-HIV AZT, and FLT drugs. The key step of those syntheses is a Pd(0) cross-coupling at C5 position under Sonogashira conditions. Finally, based on their in vitro anti-HIV activities and their cytotoxicity on PBM, CEM, and VERO cell lines, the best compounds were the 2′,3′-dideoxy-3′-fluoro-5-(bromo-2-iodo)vinyluridine (10b, EC₅₀ of 0.6 μM), and the 3′-azido-2′,3′-dideoxy-5-(bromo-2-iodo)vinyluridine (16b, EC₅₀ of 1.1 μM).     

Synthesis of diporphyrins via palladium-catalyzed C-O bond formation: effective access to chiral diporphyrins

Diporphyrins can be efficiently synthesized from bromoporphyrin precursors via palladium-catalyzed C-O bond formation. The synthetic methodology is general and can be applied to various diols, forming a series of homo-diporphyrins containing different types of spacers in high to excellent yields. Chiral diporphyrins can be readily constructed through the use of optically active diols. A similar strategy allows access to hetero-diporphyrins and triporphyrins, including free-base and metalloporphyrin hetero dimers.     

Structure revision of spiroleucettadine, a sponge alkaloid with a bicyclic core meager in H-atoms

Our 2004 disclosure of the amino hemiketal-containing spiroleucettadine was met with keen interest by the natural products and synthetic communities. As repeated efforts to synthesize spiroleucettadine failed and questions regarding the original structure elucidation process arose, evidence mounted against the validity of the proposed structure. The low ratio of H/C in the core of spiroleucattadine complicated the original structure elucidation process. Speculation prompted a reisolation of spiroleucettadine from an untouched portion of the original Luecetta collection and a thorough analysis of analytical data. In addition, a systematic analysis of candidate structures was performed via density functional theory (DFT) calculations; a favored high scoring structure 1b was ultimately confirmed to be spiroleucettadine via X-ray analysis of crystalline spiroleucettadine and reinforced the validity of DFT calculations in structure elucidation. We present the revised structure of spiroleucettadine, a bicyclic sponge alkaloid with a scarcity of H-atoms in its core.