CD44 targeting magnetic glyconanoparticles for atherosclerotic plaque imaging.

PURPOSE: The cell surface adhesion molecule CD44 plays important roles in the initiation and development of atherosclerotic plaques. We aim to develop nanoparticles that can selectively target CD44 for the non-invasive detection of atherosclerotic plaques by magnetic resonance imaging. METHODS: Magnetic glyconanoparticles with hyaluronan immobilized on the surface have been prepared. The binding of these nanoparticles with CD44 was evaluated in vitro by enzyme linked immunosorbent assay, flow cytometry and confocal microscopy. In vivo magnetic resonance imaging of plaques was performed on an atherosclerotic rabbit model. RESULTS: The magnetic glyconanoparticles can selectively bind CD44. In T2* weighted magnetic resonance images acquired in vivo, significant contrast changes in aorta walls were observed with a very low dose of the magnetic nanoparticles, allowing the detection of atherosclerotic plaques. Furthermore, imaging could be performed without significant delay after probe administration. The selectivity of hyaluronan nanoparticles in plaque imaging was established by several control experiments. CONCLUSIONS: Magnetic nanoparticles bearing surface hyaluronan enabled the imaging of atherosclerotic plaques in vivo by magnetic resonance imaging. The low dose of nanoparticles required, the possibility to image without much delay and the high biocompatibility are the advantages of these nanoparticles as contrast agents for plaque imaging.

Adrenocorticotropic hormone and cortisol levels in term infants born with meconium-stained amniotic fluid.

OBJECTIVE: To evaluate cord blood concentrations of adrenocorticotropic hormone (ACTH) and cortisol in well term infants born with and without meconium-stained amniotic fluid (MSAF) and term infants born with MSAF who experienced respiratory distress (RD). STUDY DESIGN: This was a prospective observational study. Fifty-four term infants were enrolled in the study in three groups: group 1 consisted of 18 well infants who were born with clear amniotic fluid, group 2 had 18 well infants born with MSAF, and group 3 had 18 infants born with MSAF who experienced RD in the first 24 h of age. Cord blood ACTH and cortisol concentrations were measured in infants born in all three groups. Groups 2 and 3 had serum ACTH and cortisol levels re-measured at 22-26 h of age. RESULT: The mean ACTH and cortisol levels at birth in group 3 infants were 18.3 pg/mL and 12.6 mg/dL, respectively. These were significantly lower than those in group 2 infants. CONCLUSION: Term infants born with MSAF and who experienced respiratory distress had significantly lower levels of ACTH and cortisol at birth compared with well term infants born with MSAF or clear amniotic fluid. This study suggests that inadequate response of ACTH and cortisol hormones may play a role in the development of respiratory distress in term infants with MSAF.

Development of multifunctional hyaluronan-coated nanoparticles for imaging and drug delivery to cancer cells.

Currently, there is high interest in developing multifunctional theranostic platforms for cancer monitoring and chemotherapy. Herein, we report hyaluronan (HA)-coated superparamagnetic iron oxide nanoparticles (HA-SPION) as a promising system for targeted imaging and drug delivery. When incubated with cancer cells, HA-SPIONs were rapidly taken up and the internalization of HA-SPION by cancer cells was much higher than the NPs without HA coating. The high magnetic relaxivity of HA-SPION coupled with enhanced uptake enabled magnetic resonance imaging of cancer cells. Furthermore, doxorubicin (DOX) was attached onto the nanoparticles through an acid responsive linker. While HA-SPION was not toxic to cells, DOX-HA-SPION was much more potent than free DOX to kill not only drug-sensitive but also multi-drug-resistant cancer cells. This was attributed to differential uptake mechanisms and cellular distributions of free DOX and DOX-HA-SPION in cancer cells.

Hyaluronic acid immobilized magnetic nanoparticles for active targeting and imaging of macrophages.

Imaging and targeted delivery to macrophages are promising new approaches to study and treat a variety of inflammatory diseases such as atherosclerosis. In this manuscript, we have designed and synthesized iron oxide based magnetic nanoparticles bearing hyaluronic acid (HA) on the surface to target activated macrophages. The HA-coated nanoparticles were prepared through a co-precipitation procedure followed by postsynthetic functionalization with HA and fluorescein. The nanoparticles were characterized by transmission electron microscopy, thermogravimetric analysis, elemental analysis, dynamic light scattering, and high-resolution magic angle spinning NMR and were biocompatible with cells and colloidally stable in the presence of serum. The HA immobilized on the nanoparticles retained their specific biological recognition with the HA receptor CD44, which is present on activated macrophages in high-affinity forms. Cell uptake studies demonstrated significant uptake of HA nanoparticles by activated macrophage cell line THP-1, which enabled magnetic resonance imaging of THP-1 cells. The uptake of nanoparticles was found to be both HA and CD44 dependent. Interestingly, Prussian blue staining showed that the magnetite cores of the HA-coated nanoparticles were only transiently present inside the cells, thus reducing the potential concerns of nanotoxicity. Furthermore, fluorescein on the nanoparticle was found to be delivered to the cell nucleus. Therefore, with further development, these HA functionalized magnetic nanoparticles can potentially become a useful carrier system for molecular imaging and targeted drug delivery to activated macrophages.

Chemical synthesis of a hyaluronic acid decasaccharide.

The chemical synthesis of a hyaluronic acid decasaccharide using the preactivation-based chemoselective glycosylation strategy is described. Assembly of large oligosaccharides is generally challenging due to the increased difficulties in both glycosylation and deprotection. Indeed, the same building blocks previously employed for hyaluronic acid hexasaccharide syntheses failed to yield the desired decasaccharide. After extensive experimentation, the decasaccharide backbone was successfully constructed with an overall yield of 37% from disaccharide building blocks. The trichloroacetyl group was used as the nitrogen protective group for the glucosamine units, and the addition of TMSOTf was found to be crucial to suppress the formation of trichloromethyl oxazoline side product and enable high glycosylation yield. For deprotections, the combination of a mild basic condition and the monitoring methodology using (1)H NMR allowed the removal of all base-labile protective groups, which facilitated the generation of the fully deprotected HA decasaccharide.

An Extremely Premature Neonate with Severe Anemia.

Spleen rupture in an extremely premature newborn is very rare event. High index of suspicion is required to make timely diagnosis and thereafter appropriate management. We present a rare case of an extremely premature, extremely low birthweight newborn who presented with severe anemia secondary to splenic rupture. It was managed conservatively without splenectomy resulting in complete resolution of symptoms. Although non-operative management of pediatric splenic injuries is now recognized as the treatment of choice, there is very little experience in premature newborns.

Recommendations for Selection and Characterization of Protein Biomarker Assay Calibrator Material.

As biomarkers continue to become an integral part of drug development and decision-making, there are increased expectations for reliable and quantitative assays. Protein biomarker assay results are directly influenced by the calibrator material. The selection of calibrator material presents many challenges that impact the relative accuracy and performance of the assay. There is an industry-wide challenge finding reliable and well-characterized calibrator material with good documentation. Several case studies are presented that demonstrate some of the challenges involved in selecting appropriate calibrators along with the resolutions that were ultimately applied. From these experiences, we present here a set of recommendations for selecting and characterizing calibrator material based on the intended purpose of the assay. Finally, we introduce a commutability approach, based on common clinical chemistry practices, which can be used to demonstrate inter-changeability with calibrator materials across multiple lots and technology platforms for all types of protein biomarker assays.

Revisiting the armed-disarmed concept rationale: s-benzoxazolyl glycosides in chemoselective oligosaccharide synthesis.

[reaction: see text]. It has been discovered that 2-O-benzyl-3,4,6-tri-O-acyl SBox glycosides are significantly less reactive than even "disarmed" peracylated derivatives. This finding has been applied to the synthesis of various oligosaccharides, the monomeric units of which are connected via cis-cis, trans-cis, and cis-trans sequential glycosidic linkages. Two-stage activation of the armed (benzylated) donor over moderately (dis)armed (acylated) and, subsequently, over disarmed (2-O-benzyl-3,4-O-diacylated) acceptor has also proven to be feasible.

A Concise Synthesis of the Repeating Unit of Capsular Polysaccharide Staphylococcus aureus Type 8.

The first synthesis of the repeating unit of S. aureus capsular polysaccharide type 8 is described. The repeating unit is an unusual trisaccharide sequence of three uncommon sugars, all connected via 1,2-cis linkages. The synthetic trisaccharide was equipped with capping methyl groups at the points of propagation of the polysaccharide sequence.

Direct synthesis of diastereomerically pure glycosyl sulfonium salts.

It is reported that stable glycosyl sulfonium salts can be generated via direct anomeric S-methylation of ethylthioglycosides. Mechanistically, this pathway represents the first step in the activation of thioglycosides for glycosidation; however, it can further allow for the synthesis and isolation of quasi-stable sulfonium ions, representing a new approach for studying these key intermediates.

Synthesis of an Fmoc-threonine bearing core-2 glycan: a building block for PSGL-1 via Fmoc-assisted solid-phase peptide synthesis.

Selectins (L, E, and P) are vascular endothelial molecules that play an important role in the recruitment of leukocytes to inflamed tissue. In this regard, P-Selectin glycoprotein-1 (PSGL-1) has been identified as a ligand for P-Selectin. PSGL-1 binds to P-Selectin through the interaction of core-2 O-glycan expressing sialyl Lewis(x) oligosaccharide and the three tyrosine sulfate residues. Herein, we report the synthesis of threonine-linked core-2 O-glycan as an amino acid building block for the synthesis of PSGL-1. This building block was further incorporated in the Fmoc-assisted solid-phase peptide synthesis to provide a portion of the PSGL-1 glycopeptide.

Application of glycosyl thioimidates in solid-phase oligosaccharide synthesis.

Two stable classes of thioimidoyl derivatives, S-benzoxazolyl (SBox) and S-thiazolinyl (STaz) glycosides, were investigated as glycosyl donors for solid-phase oligosaccharide synthesis. It was demonstrated that these derivatives are suitable for both glycosyl acceptor-bound and glycosyl donor-bound strategies, commonly employed in resin-supported oligosaccharide synthesis.

Versatile synthesis and mechanism of activation of S-benzoxazolyl glycosides.

As a part of a program for developing new efficient procedures for stereoselective glycosylation, a range of S-benzoxazolyl (SBox) glycosides have been synthesized. The mechanistic aspects of the SBox moiety activation for glycosylation via a variety of conceptually different pathways in the presence of thiophilic, electrophilic, or metal-based promoters have been investigated.

S-benzoxazolyl as a stable protecting moiety and a potent anomeric leaving group in oligosaccharide synthesis.

As a part of a program for developing new versatile building blocks for stereoselective glycosylation and convergent oligosaccharide synthesis, we demonstrated that S-benzoxazolyl (SBox) glycosides are stable toward major protecting group manipulations employed in carbohydrate chemistry. On the other hand, they can be glycosidated under relatively mild reaction conditions to afford either 1,2-trans or 1,2-cis-linked disaccharides. Selective and chemoselective activations of the SBox moiety were also proved to be feasible, which was demonstrated by synthesizing a number of oligosaccharide sequences.

Chemoselective synthesis of oligosaccharides of 2-deoxy-2-aminosugars.

Along with the application of the S-benzoxazolyl glycosides to the high-yielding synthesis of disaccharides of the 2-amino-2-deoxy series, chemoselective assembly of oligosaccharides containing multiple residues of 2-amino-2-deoxyglycoses is reported. This modified armed-disarmed approach is relying on the observation that 2-N-trichloroethoxycarbonyl derivatives of S-benzoxazolyl glycosides are significantly more reactive than their 2-N-phthaloyl counterparts in MeOTf-promoted glycosylations. This allowed efficient chemoselective synthesis of 1,2-trans-linked oligosaccharides, the disarmed reducing end of which can be activated for immediate second step glycosidation in the presence of a more powerful activator, AgOTf. As a result of this two-step activation, trans-trans-patterned trisaccharides could be assembled in a highly efficient manner. This result differs from the classic armed-disarmed technique, according to which usually cis-trans-patterned oligosaccharides are generated.