Natural Glycoforms of Human Interleukin 6 Show Atypical Plasma Clearance.

A library of glycoforms of human interleukin 6 (IL-6) comprising complex and mannosidic N-glycans was generated by semisynthesis. The three segments were connected by sequential native chemical ligation followed by two-step refolding. The central glycopeptide segments were assembled by pseudoproline-assisted Lansbury aspartylation and subsequent enzymatic elongation of complex N-glycans.

S-Glycosides: synthesis of S-linked arabinoxylan oligosaccharides.

S-Glycosides are important tools for the elucidation of specific protein-carbohydrate interactions and can significantly aid structural and functional studies of carbohydrate-active enzymes, as they are often inert or act as enzyme inhibitors. In this context, this work focuses on the introduction of an S-linkage into arabinoxylan oligosaccharides (AXs) in order to obtain a small collection of synthetic tools for the study of AXs degrading enzymes. The key step for the introduction of the S-glycosidic linkage involved anomeric thiol S-alkylation of an orthogonally protected l-arabinopyranoside triflate.

Synthesis of Erythropoietins Site-Specifically Conjugated with Complex-Type N-Glycans.

The biological activity of the glycoprotein hormone erythropoietin (EPO) is dependent mainly on the structure of its N-linked glycans. We aimed to readily attach defined N-glycans to EPO through copper-catalyzed azide alkyne cycloaddition. EPO variants with an alkyne-bearing non-natural amino acid (Plk) at the N-glycosylation sites 24, 38, and 83 were obtained by amber suppression followed by protein purification and refolding.

Substrate specificity of novel GH16 endo-β-(1→3)-galactanases acting on linear and branched β-(1→3)-galactooligosaccharides.

Arabinogalactan proteins are proteoglycans located in the plant cell wall. Most arabinogalactan proteins are composed of carbohydrate moieties of β-(1→3)-galactan main chains with β-(1→6)-galactan side chains terminated by other glycans. In this study, three novel endo-β-(1→3)-galactanases were identified and the substrate specificity was further studied using well-defined galactan oligomers.

Galectin binding to cells and glycoproteins with genetically modified glycosylation reveals galectin-glycan specificities in a natural context.

Galectins compose a protein family defined by a conserved sequence motif conferring affinity for β-galactose-containing glycans. Moreover, galectins gain higher affinity and fine-tune specificity by glycan interactions at sites adjacent to their β-galactoside-binding site, as revealed by extensive testing against panels of purified glycans. However, in cells, galectins bind glycans on glycoproteins and glycolipids in the context of other cellular components, such as at the cell surface.

A Tomato Tocopherol-Binding Protein Sheds Light on Intracellular α-Tocopherol Metabolism in Plants.

Tocopherols are non-polar compounds synthesized in the plastids, which function as major antioxidants of the plant cells and are essential in the human diet. Both the intermediates and final products of the tocopherol biosynthetic pathway must cross plastid membranes to reach their sites of action. So far, no protein with tocopherol binding activity has been reported in plants.

Synthesis of branched and linear 1,4-linked galactan oligosaccharides.

We report the synthesis of linear and branched (1→4)-d-galactans. Four tetrasaccharides and one pentasaccharide were accessed by adopting a procedure of regioselective ring opening of a 4,6-O-naphthylidene protecting group followed by glycosylation using phenyl thioglycoside donors. The binding of the linear pentasaccharide with galectin-3 is also investigated by the determination of a co-crystal structure.

Synthesis and Application of Branched Type II Arabinogalactans.

The synthesis of linear and (1 → 6)-branched β-(1 → 3)-d-galactans, structures found in plant arabinogalactan proteins (AGPs), is described. The synthetic strategy relies on iterative couplings of monosaccharide and disaccharide thioglycoside donors, followed by a late-stage glycosylation of heptagalactan backbone acceptors to introduce branching. A key finding from the synthetic study was the need to match protective groups in order to tune reactivity and ensure selectivity during the assembly.

Breaking the Limits in Analyzing Carbohydrate Recognition by NMR Spectroscopy: Resolving Branch-Selective Interaction of a Tetra-Antennary N-Glycan with Lectins.

The biological recognition of complex-type N-glycans is part of many key physiological and pathological events. Despite their importance, the structural characterization of these events remains unsolved. The inherent flexibility of N-glycans hampers crystallization and the chemical equivalence of individual branches precludes their NMR characterization.

A Synthetic Glycan Microarray Enables Epitope Mapping of Plant Cell Wall Glycan-Directed Antibodies.

In the last three decades, more than 200 monoclonal antibodies have been raised against most classes of plant cell wall polysaccharides by different laboratories worldwide. These antibodies are widely used to identify differences in plant cell wall components in mutants, organ and tissue types, and developmental stages. Despite their importance and broad use, the precise binding epitope has been determined for only a few of these antibodies.

Synthetic Glycoforms Reveal Carbohydrate-Dependent Bioactivity of Human Saposin D.

The main glycoforms of the hydrophobic lysosomal glycoprotein saposin D (SapD) were synthesized by native chemical ligation. An approach for the challenging solid-phase synthesis of the fragments was developed. Three SapD glycoforms were obtained following a general and robust refolding and purification protocol.

Convergent strategy for the synthesis of S-linked oligoxylans.

Arabinoxylans (AX) are a major class of hemicellulose and an important polysaccharide component of lignocellulosic biomass. To utilize the glycan polymer effectively, it is desirable to learn more about the enzymatic hydrolysis of AXs. Well-defined glycans can help to elucidate these processes.

A recombinant fungal lectin for labeling truncated glycans on human cancer cells.

Cell surface glycoconjugates present alterations of their structures in chronic diseases and distinct oligosaccharide epitopes have been associated with cancer. Among them, truncated glycans present terminal non-reducing β-N-acetylglucosamine (GlcNAc) residues that are rare on healthy tissues. Lectins from unconventional sources such as fungi or algi provide novel markers that bind specifically to such epitopes, but their availability may be challenging.

Semisynthesis of biologically active glycoforms of the human cytokine interleukin 6.

Human interleukin 6 (IL-6) is a potent cytokine with immunomodulatory properties. As the influence of N-glycosylation on the in vivo activities of IL-6 could not be elucidated so far, a semisynthesis of homogeneous glycoforms of IL-6 was established by sequential native chemical ligation. The four cysteines of IL-6 are convenient for ligations and require only the short synthetic glycopeptide 43-48.

Breaking pseudo-symmetry in multiantennary complex N-glycans using lanthanide-binding tags and NMR pseudo-contact shifts.

Controlling NMR shifts by lanthanides tagged to a "symmetrical" N-glycan reveals individual resonances for the residues of the otherwise identical A and B arms. This method provides a global perspective of conformational features and interactions in solution.

Three year results of endovascular therapy with a new generation nitinol stent for femoro-popliteal artery lesions - a single-center outcome analysis of a subcohort of MISAGO 2 study.

Background: Advances in stent technology have widened the field of indications for stent treatment of femoro-popliteal artery lesions, however the use of stents in bending arterial segments is restricted because some first- and second-generation nitinol stent designs did not respond well to the mechanical forces of femoro-popliteal segments in motion which pose a substantial risk of stent fracture inducing in-stent-stenosis. New generation nitinol stents are supposed to overcome these limitations but long-term results are rare.

Patients And Methods: In forty-five patients (mean age 68 y, range 50 - 85) with peripheral arterial disease (TASC II A-C, Rutherford category 2 - 5) forty-six lesions of the superficial femoral artery (37) or popliteal artery (9) were treated [25 high-grade stenoses, mean length 53 mm (range 30 - 145 mm); 21 chronic total occlusions, mean length 74 mm (range 30 - 180 mm)].

Development of a new intravascular low-profile device for exclusion of aortic aneurysm: an experimental pilot study.

Purpose: To present a new intravascular device for the treatment of aorto-iliac aneurysms.

Methods: This new device was tested in five dogs with abdominal aortic aneurysm created experimentally by over-dilation of a balloon-expandable stent with a 16 or 18 mm wide PTA balloon catheter. The design of the device is based on a self-expanding aortic stent which consists of two stretchable circular frames filled with a textile Dacron mesh membrane that is suspended horizontally into the infrarenal abdominal aorta proximally to the aneurysm.

Clopidogrel plus long-term aspirin after femoro-popliteal stenting. The CLAFS project: 1- and 2-year results.

The aim of this study was to determine the patency rate after femoro-popliteal stenting followed by oral clopidogrel plus long-term aspirin. In a prospective trial, 31 patients with a total of 33 femoro-popliteal artery lesions (21 stenoses, 12 occlusions; 24 femoral, 9 popliteal) were treated with flexible tantalum stents after unsuccessful percutaneous transluminal angioplasty (PTA) preceded by local fibrinolysis in 5 of 12 patients with total occlusion. Post-interventionally, oral aspirin 100 mg was started simultaneously for the long term and was combined with an oral loading dose of 300 mg clopidogrel, followed by 75 mg clopidogrel daily for 28 days.

Preliminary experience with locoregional intraarterial chemotherapy of uterine cervical or endometrial cancer using the peripheral implantable port system (PIPS): a feasibility study.

The purpose of this study was to assess the suitability of a percutaneously implantable catheter port system (PIPS) for repeated intraarterial locoregional chemotherapy (ILC) for cervical and endometrial carcinoma. In 30 patients with advanced, recurrent, or high-risk cervical (n = 23) or endometrial (n = 7) carcinoma, PIPS for ILC was implanted via a femoral access, the catheter localized in the infrarenal abdominal aorta. Chemotherapy was performed adjuvantly after surgery (n = 14) or neo-adjuvantly to enable surgery, or for palliation (n = 16).

Popliteal artery stenting using flexible tantalum stents.

Purpose: To evaluate the safety and efficacy of stent therapy for the treatment of residual stenoses after percutaneous transluminal angioplasty (PTA) of popliteal stenoses and occlusions.

Methods: In a prospective single-center study, flexible tantalum stents were implanted in 32 popliteal arteries for the treatment of residual stenosis greater than 50% after PTA of stenoses (n = 17) or occlusions (n = 15) in the P1 (n = 16), the P2 (n = 13), or both P1 and P2 segment (n = 3). Follow-up patency was assessed by clinical examination, ankle-brachial index, and color Doppler sonography or angiography.

Improvement in claudication after angioplasty of distal ostial collateral stenosis in patients with long-segment occlusion of the femoral artery.

Purpose: To evaluate the angiographic and clinical effects of percutaneous transluminal angioplasty (PTA) of distal ostial collateral stenoses in patients with claudication and long-segment occlusion of the superficial femoral artery (SFA).

Methods: In ten patients (9 men, 1 woman) with stable intermittent claudication due to chronic long-segment occlusion of the SFA a high-grade stenosis of the distal collateral ostium of the deep femoral artery to the popliteal artery were dilated. PTA was performed using popliteal artery access.

Flexible tantalum stents for the treatment of renovascular hypertension: a 10-year experience.

The aim of this study was to determine long-term success of flexible tantalum stents for the treatment of ostial and truncal renal artery stenosis. Since 1989, flexible tantalum stents (type Strecker) were implanted in 34 patients (36 arteries, 25 ostial lesions, 11 truncal lesions) with uncontrollable renovascular hypertension, 9 of them in association with renal insufficiency. Stents were placed unilaterally in 32 patients, and bilaterally in 2 patients for the treatment of renal artery stenosis.

[Dose-dependent decrease of the rate of restenosis of stents in peripheral vessels with reviparin].

Purpose: In clinical prospective trials, we examined the effect of the low molecular weight heparin (lmwh) reviparin on restenosis rate after Strecker stent implantation in femoral popliteal arteries.

Materials And Methods: 62 patients were treated between 1992 and 1998. Patients received reviparin, 3500 IU, prior to stent implantation followed by 7500 IU for 24 h (i.