1,721,039 research outputs found
Chemical contributions to understanding heparin activity: Synthesis of related sulfated oligosaccharides
No full textHeparin and heparan sulfate are complex polysaccharides that modulate several biological events through the recognition of a number of distinct proteins. Chemical synthesis is a powerful tool to identify the unique binding domains responsible for the specific interactions and to generate potent analogues of the natural sequences. The present review reports the synthetic efforts of the last decade that are focused on the preparation of tailored fragments of these two polymers and analogues thereof. (C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003
Corrigendum to “Ionic liquid mediated synthesis of peptide nucleic acids dimers” [Tetrahedron 69 (2013) 1940e1944]
No full textIonic liquid mediated synthesis of peptide nucleic acids dimers
No full textThe unprecedented use of ionic liquids in the synthesis of peptide nucleic acids (PNA) oligomers has been investigated. As a proof of concept, the preparation of PNA dimers in ILs has been performed using last generation coupling reagents. More importantly, the application of the supported ionic liquid phase (SILP) technique to the preparation of a PNA dimer has been achieved, including loading, chain elongation and cleavage from the IL support of the PNA fragment
Carbohydrates and Immunology : Synthetic Oligosaccharide Antigens for Vaccine Formulation
No full textDespite the enormous progress achieved by modern medicine,
numerous diseases still have a profound impact on public
health. Infectious diseases caused by a variety of microorganisms
(viruses, fungi and parasites) and bacteria are a
global major concern and, because of the emergence, for instance,
of multidrug resistance, not only in developing countries.
The development of preventative therapies, such as the
rational design of novel and more efficient vaccines, might
offer a solution to this state of affairs and other associated
drawbacks. Vaccination is considered by the World Health
Organization to be the most cost-effective strategy for controlling
infectious disease, because it should confer long-term
protective immunity in the population. A second consideration
involves cancer. The outstanding progress achieved in
the identification and structural characterization of tumourassociated
antigens has prompted their employment in tumour
immunotherapy, on the basis of the observation that
tumour cells possess specific antigens that can be recognized
by an immune system appropriately conditioned to the task. Carbohydrates play key roles in many molecular recognition
phenomena and they can affect any kind of interaction with
the immune system. Saccharide-based antigens (bacterial
capsular polysaccharides or tumour-associated carbohydrate
antigens, for instance) have therefore been studied and employed
in the formulation of vaccines. In recent years there
has been increasing use of synthetic saccharide antigens for
the formulation of vaccine candidates. These structures are
indeed chemically well defined, devoid of biologic contaminants
and, in principle, available in large amounts, relative
to materials extracted from natural sources. In addition, synthetic
saccharide antigens can also serve as haptens in protein
conjugates, eliciting highly specific antibodies in animal
models and humans. The great potential of synthetic saccharide
antigens is attested to by the spectacular success of the
Cuban vaccine against Haemophilus influenzae type b. Here
we review the major advances in the development of synthetic
carbohydrate-based vaccines targeted against infectious
diseases and cancer
Synthesis of Fragment of beta-Glucans as Potential Ligands for Dectin-1
No full textBeta-glucans are glucose polymers linked together by a 1,3 linear beta-glycosidic chain core, differing from each other by their length and branching configuration. The branches derived from the glycosidic chain core are either 1,4 or 1,6 glycosidic chains and appear to be dependent on the source.
Dectin-1 is a unique C-type lectin that recognizes beta-glucan carbohydrates present on the surface of various fungi, including C. albicans. Its activation promotes microbial uptake and phagocytosis, but also mediates, in synergy with TLRs, the production of cytokines such as IL-12 and TNF alfa, leading ultimately to the initiation of the adaptive immune response. For this reason, beta-glucans – or their fragments – can be referred to as a possible class of adjuvants to increase the immune response to pathogens. In addition, the administration of beta-glucan-derived compounds can help in gaining new insights on the mechanism of action of dectin-1 receptor.
Dectin-1 binds beta-glucan polymers with affinities ranging from very low (3x10-3 M) to very high (2x10-12 M). The wide range of affinities appears to be due to the differing sizes and numbers of branches in -glucans from various sources.
Although the interaction between Dectin-1 and beta-glucans has been supposed to involve a conformational epitope as a high order local helix, little is known about the binding mode and the degree of (1-6)-branching of the glucan chain in the binding epitope. For this reason, a series of fragments of beta-glucans, differing in the 6-O branching degree, has been synthesised. Their ability to bind to dectin-1 and of activating the inflammatory response will be subsequently tested
Synthesis of PNA in non conventional media
No full textThe growing awareness of the urgent need for greener, more sustainable
technologies has focused the scientific attention on the use of alternative reaction
media that circumvent the problems associated with the traditional volatile organic
solvents (VOCs). The use of non conventional reaction media also provides
opportunities to facilitate the recovery and the recycling of the reaction solvent.
Among the most promising alternatives to classical organic solvents, ionic liquids
(ILs) have been intensely studied in the recent years as potential environmentally
benign reaction media due to their lack of measurable vapour pressure and high
thermal and chemical stability.
Recently, room temperature Ionic liquids (RTILs) have been used as solvents in the
preparation of several classes of biomolecules such as oligosaccharides and
peptides.
In this communication we report a preliminary study on the use of ILs as solvents
in the preparation of peptide nucleic acids (PNAs).
The optimization of the reaction conditions, as well as the recycling of the ILs and
the use of microwave will be discussed
Riflessioni per una corretta cultura del debito famigliare
No full textDa diversi anni in Italia si è rafforzato il comparto dei finanziamenti rivolti alle famiglie, con riguardo sia al finanziamento dell’investimento immobiliare sia con riguardo al sostegno del consumo.
Per alcuni questo elemento è da considerare positivamente, come segnale di sviluppo e ammodernamento del mercato finanziario; per altri ha un prevalente connotato negativo, come segnale di indebolimento delle condizioni finanziarie e della capacità di risparmio dei mutuatari o come una prevalente e diffusa mancanza di consapevolezza e attenzione verso un attento comportamento di spesa.
La situazione che si è definita viene puoi giudicata estremamente pericolosa in relazione alle possibili conseguenze di comportamenti superficiali di indebitamento in un contesto di instabilità finanziaria.
Le nuove vie di un’attività customer oriented suggeriscono una speranza
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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