Capillary electrophoresis separation of human milk neutral and acidic oligosaccharides derivatized with 2-aminoacridone

Human milk is a unique fluid in glycobiology due to the presence of many free structurally complex oligosaccharides emerging as important dietary factors during early life and having many biological and protective functions. Methods that allow accurate profiling of oligosaccharide mixtures in this complex biological fluid with quantification of the four known genetically determined groups are welcomed. A high-voltage CE separation and detection at 254 nm of 17 neutral and acidic human milk oligosaccharide (HMO) standard along with lactose derivatized with 2-aminoacridone, using a BGE containing 20% methanol as an organic modifier and borate, able to form on-capillary anionic borate-polyol complexes, is reported. This CE approach was able to separate both neutral HMOs and acidic HMOs, with the sialic acid residue, also in the presence of lactose in high content. This method was applied to the four secretory groups individually extracted by a rapid and simple preparative step. LODs were found ranging from ∼50 to 700 fmol. We were able to measure HMO content also in the presence of excess fluorophore, or interference from proteins, peptides, salts, and other impurities normally present in this complex biological fluid. Overall, CE equipped with a UV detector is a common analytical approach and this simple CE separation offers high resolution and sensitivity for the differentiation of human milk samples related to genetic groups and days of lactation by considering that important changes in HMO content are a reflection of the lactation day.

Selective removal of keratan sulfate in chondroitin sulfate samples by sequential precipitation with ethanol

Keratan sulfate (KS) is present as a contaminant in chondroitin sulfate (CS) mainly extracted from shark cartilage. We report a selective removal procedure of KS in CS samples by means of sequential precipitation with ethanol. Purified shark CS containing approximately 10% to 15% KS was subjected to a precipitation procedure in the presence of increasing percentages of saturated ethanol. In contrast to other solvents, 1.0 volume of ethanol was able to selectively purify CS, with a purity of approximately 100%, from KS. The current selective and simple procedure appears to be a reliable industrial preparation of CS devoid of large amounts of the residual KS.

Aortic valve leaflet glycosaminoglycans composition and modification in severe chronic valve regurgitation

BACKGROUND AND AIM OF THE STUDY

The surgical segments of aortic valve leaflets from patients with severe chronic aortic regurgitation were analyzed (by percentage and structure) for their content of complex polysaccharides and glycosaminoglycans (GAGs), and compared with control segments.

METHODS

The GAG, hyaluronic acid (HA), chondroitin sulfate (CS) and dermatan sulfate (DS) and disaccharide contents were determined in segments (leaflet, root attachment region and belly) of aortic valve leaflets (non-coronary, left coronary and right coronary) using a multi-analytical approach.

RESULTS

The aortic valve leaflets showed the presence of HA and CS/DS, with an overall charge density of -0.51-0.55. The CS/DS polymers showed a 4-sulfated/6-sulfated ratio of -0.70-0.77 in the belly, and -1.60-1.72 in commissure parts (-/+124%). The total amount of GAGs was -1.60-2.40 microg/mg of tissue. A significant increase in sulfated GAGs was observed in all valve parts in patients suffering from severe aortic insufficiency, as well as an increase in the 4-sulfated/6-sulfated ratio in the leaflet belly (-/+102%).

CONCLUSION

It is speculated that differences in 4-sulfated/6-sulfated ratio determined in the belly and leaflet attachment region-commissure parts of the leaflets may correlate with the tensile or compressive loading of normal aortic valve regions. At the same time, it may be assumed that the increase in sulfated GAGs and 4-sulfated/6-sulfated ratio in the leaflet belly of valves taken from patients suffering severe aortic insufficiency was consistent with an altered matrix microstructure capable of influencing the hydration of these pathological tissues, and of conditioning their mechanical weakness.

Plasmatic kinetics of dermatan sulfate during enzyme replacement therapy with iduronate-2-sulfatase in a mucopolysaccharidosis II patient

Enzyme replacement therapy (ERT) is the worldwide standard of care for a number of mucopolysaccharidosis (MPS) diseases. We report a kinetic study of plasmatic dermatan sulfate (DS) in a 3-year-old subject affected by a severe form of MPS II during the first 10 months of ERT with Idursulfase. A strong increase in the DS plasmatic concentration was measured immediately after the first enzyme infusion, with a maximum after 3 h, followed by a continuous decrease in the 8-15 days following the beginning of treatment. After this, a constant plasmatic content of DS concentration was observed. Overall, during the 10-month treatment period, ERT reduced the plasmatic concentration of DS up to ~80-85 %, but it was unable to totally remove it from the blood. We can suppose that immediately after the first enzyme administrations, a large amount of abnormal DS is removed from tissues reaching the blood compartment and eliminated via the urine, and thereafter only minimal changes are observed. The persistency of the residual amounts of DS with the actually recommended dosage in our Patient may suggest the opportunity to promote further studies with increased enzyme dosages to completely remove the accumulation of lysosomal DS.

Human milk glycosaminoglycans: the state of the art and future perspectives

Recently, a complete characterization and detailed evaluation of the glycosaminoglycans of human milk were performed. The total glycosaminoglycans content in milk from healthy mothers having delivered term or preterm newborns showed a constant pattern which was essentially composed of two main polysaccharides: chondroitin sulfate (60-70%) and heparin (30-40%). Moreover, considerable variations of glycosaminoglycans concentration were found during the first month of lactation, the highest values being present in colostrum compared to mature milk. Metabolism and potential biological functions of human milk glycosaminoglycans are hypothesized and future studies are encouraged.

Evaluation of risk factors for body weight increment in psoriatic patients on infliximab: a multicentre, cross-sectional study

BACKGROUND

A significant weight gain has been reported in patients with psoriasis treated with anti-tumour necrosis factor-alpha agents. Among these patients, there are contradictory results about risk factors for weight gain.

OBJECTIVE

Assessing risk factors for weight increment in psoriatic patients on infliximab (IFX).

METHODS

This study was a 4-month, non-interventional, cross-sectional, multicentre study on adults with psoriasis performed in 19 French dermatological centres. All the patients who received IFX for at least 1 year were prospectively included, with retrospective analysis of data. Impact of sex, age, severity of the disease, cardiovascular and metabolic comorbidities, and previous and simultaneous systemic treatments on weight changes, was analysed. Weight gain was defined as an increment of more than 2% of baseline weight.

RESULTS

Overall, 191 psoriatic patients (males: 68.6%; mean age: 46.9 years) were included. Mean weight gain was 1.6 kg (2.1%) after 1 year of IFX. Half (48.2%) suffered from a weight gain, and 9.9% from a weight increment of 10% or more. Baseline weight and Body Mass Index, and cardiovascular and metabolic comorbidities did not influence weight. Men (P=0.007) and patients with severe psoriasis (BSA, P=0.005) had a tendency to put on weight. Patients with a hospital dietary follow-up (P=0.01; OR=0.36 [0.16-0.79]) and patients on methotrexate (P=0.03; OR=0.41 [0.18-0.93]) during IFX treatment are thinner, in a multivariate analysis.

CONCLUSION

Severe weight increment is frequent on IFX treatment, mainly in men, and patients with severe psoriasis. Dietary follow-up or simultaneous use of methotrexate could limit this weight increment.

Electrophoresis for the analysis of heparin purity and quality

The adulteration of raw heparin with oversulfated chondroitin sulfate (OSCS) in 2007-2008 produced a global crisis resulting in extensive revisions to the pharmacopeia monographs and prompting the FDA to recommend the development of additional methods for the analysis of heparin purity. As a consequence, a wide variety of innovative analytical approaches have been developed for the quality assurance and purity of unfractionated and low-molecular-weight heparins. This review discusses recent developments in electrophoresis techniques available for the sensitive separation, detection, and partial structural characterization of heparin contaminants. In particular, this review summarizes recent publications on heparin quality and related impurity analysis using electrophoretic separations such as capillary electrophoresis (CE) of intact polysaccharides and hexosamines derived from their acidic hydrolysis, and polyacrylamide gel electrophoresis (PAGE) for the separation of heparin samples without and in the presence of its relatively specific depolymerization process with nitrous acid treatment.

On-line high-performance liquid chromatography-fluorescence detection-electrospray ionization-mass spectrometry profiling of human milk oligosaccharides derivatized with 2-aminoacridone

A high-resolution normal-phase high-performance liquid chromatography-fluorescence detection-electrospray ionization-mass spectrometry separation and structural characterization of the main oligosaccharides along with lactose from human milk samples is described. A total of 22 commercially available oligosaccharides were fluorotagged with 2-aminoacridone and separated on an amide column and identified on the basis of their retention times and mass spectra. Derivatized species having mass lower than approximately 800 to 900 exhibited mainly [M-H](-1) anions, oligomers with mass up to approximately 1000 to 1100 were represented by both [M-H](-1) and [M-2H](-2) anions, and oligomers greater than approximately 1200 to 1300 were characterized by a charge state of -3. Furthermore, the retention times were directly related to the glycans' molecular mass. Human milk samples from the four groups of donors (Se±/Le±) were analyzed for their composition and amount of free oligosaccharides after rapid and simple prepurification and derivatization steps also in the presence of lactose in high content. This analytical approach enabled us to perform the determination of species not detected by traditional techniques, such as sialic acid, as well as of species present in low content easily mistaken with other peaks. Finally, labeled human milk oligosaccharides were analyzed without any interference from excess fluorophore or interference from proteins, peptides, salts, and other impurities normally present in this complex biological fluid.

Glycosaminoglycan content in term and preterm milk during the first month of lactation

BACKGROUND

In a recent study, we performed a complete structural characterization of glycosaminoglycans (GAGs) in human mature milk. However, no data are available on the total content of GAGs in human milk from healthy mothers having delivered term or preterm newborns.

OBJECTIVES

In this study, we evaluated the total content of GAGs in pooled milk from healthy mothers having delivered term or preterm newborns during the first month of lactation.

METHODS

Highly specific and sensitive analytical approaches were used to quantify human milk total GAGs.

RESULTS

Highest GAG values are present at day 4 (9.3 and 3.8 g/l in preterm and term milk, respectively), followed by a progressive decrease up to day 30 (4.3 and 0.4 g/l). The more remarkable differences are related to the first phases of lactation in which a strong decrease in GAGs was observed between days 4 and 10 (about -73% in term and -50% in preterm newborns).

CONCLUSIONS

During the first month of lactation, the absolute amount of polysaccharides was constantly and significantly higher in preterm than in term milk, with a similar behavior in the decrease. These data further indicate that human milk GAGs may have an active role in protecting newborns during the first phases of lactation.

Composition and structure elucidation of human milk glycosaminoglycans

To date, there is no complete structural characterization of human milk glycosaminoglycans (GAGs) available nor do any data exist on their composition in bovine milk. Total GAGs were determined on extracts from human and bovine milk. Samples were subjected to digestion with specific enzymes, treated with nitrous acid, and analyzed by agarose-gel electrophoresis and high-performance liquid chromatography for their structural characterization. Quantitative analyses yielded ∼7 times more GAGs in human milk than in bovine milk. In particular, galactosaminoglycans, chondroitin sulfate (CS) and dermatan sulfate (DS), were found to differ considerably from one type of milk to the other. In fact, hardly any DS was observed in human milk, but a low-sulfated CS having a very low charge density of 0.36 was found. On the contrary, bovine milk galactosaminoglycans were demonstrated to be composed of ∼66% DS and 34% CS for a total charge density of 0.94. Structural analysis performed by heparinases showed a prevalence of fast-moving heparin over heparan sulfate, accounting for ∼30-40% of total GAGs in both milk samples and showing lower sulfation in human (2.03) compared with bovine (2.28). Hyaluronic acid was found in minor amounts. This study offers the first full characterization of the GAGs in human milk, providing useful data to gain a better understanding of their physiological role, as well as of their fundamental contribution to the health of the newborn.

beta-Amyloid fibrillation and/or hyperhomocysteinemia modify striatal patterns of hyaluronic acid and dermatan sulfate: Possible role in the pathogenesis of Alzheimer's disease

A key event in Alzheimer's disease (AD) pathogenesis is the formation of insoluble peptides beta-amyloid aggregates and this process is favoured by a condition of hyperhomocysteinemia. To date, there is growing evidence that implicates glycosaminoglycans (GAGs) in the pathophysiology of amyloidosis but no data are available on the characterization of brain GAGs involved in the enhancing beta-amyloid fibrillogenesis in relationship to their structure and physico-chemical properties. Furthermore, few studies have been performed on the relationship between hyperhomocysteinemia and extracellular matrix (ECM) modifications. The aim of this study was to evaluate the amount and chemical structure of GAGs in rat striatal areas where beta-amyioid fibrillogenesis was induced, and in conditions of hyperhomocysteinemia. The intrastriatal injection of beta-amyloid produced a significant decrease (-40.8%) in the hyaluronic acid (HA) percentage and an increase (+14.5%) in the dermatan sulfate (DS) with a total charge density increasing of 14.9%. A significant decrease (-19.5%) in the HA percentage and an increase (+6.9%) in the DS % was also observed in striata obtained from the hyperhomocysteinemic animals. The total charge density increased by 6.8%. Quite the same trend was observed in rats after intrastriatal injection of beta-amyloid and in a condition of hyperhomocysteinemia. The observed increase of DS concentration and the correspondent decrease of the nonsulfated polymer HA after in vivo treatment with beta-amyloid and in a condition of hyperhocysteinemia support the hypothesis that an increase in local production of sulfated GAGs may reduce beta-amyloid neurotoxicity. However, the consequent modification of the ECM network might impair the extracellular diffusion pathways of different signal molecules and participate in the progression of AD.