Structural characterization of the skin glycosaminoglycans in patients with pseudoxanthoma elasticum

BACKGROUND

Complex polysaccharides, glycosaminoglycans (GAGs), their amount, and fine structure were determined in the skin (epidermis + dermis) of pseudoxanthoma elasticum (PXE)-affected patients in comparison with healthy subjects.

METHODS

Nonlesional skin GAGs were extracted and specifically determined by enzymatic treatment and high-performance liquid chromatography separation.

RESULTS

Dermatan sulfate (DS) and hyaluronic acid (HA) were found to be the major GAG species in normal subjects, with contents of approximately 20% for DS and 58% for HA. The chondroitin sulfate (CS) content (unsaturated six-sulfated disaccharide) was approximately 21%. Skin from patients with PXE showed similar HA (61%), DS (22%), and CS (16.7%) contents. No change in the total charge density or nonsulfated/sulfated GAG ratio was noted in PXE-affected subjects, and no modification of the position of the sulfate groups (4s/6s) on the CS/DS backbone. A significant increase (approximately 88%; P < 0.01) in the total amount of GAGs (HA + DS + CS) was found in the PXE group vs. normal subjects, however.

CONCLUSIONS

In the skin of PXE-affected patients, the altered metabolic processes produce an increase in the total amount of GAGs able to accumulate salts, in particular calcium ions, within the elastic fibers, producing ion precipitates that affect the organization of the matrix fiber.

Fluorophore-assisted carbohydrate electrophoresis for the determination of molecular mass of heparins and low-molecular-weight (LMW) heparins

We report the use of fluorophore-assisted carbohydrate electrophoresis (FACE) to determine the molecular mass (M) values of heparins (Heps) and low-molecular-weight (LMW)-Hep derivatives. Hep are labeled with 8-aminonaphthalene-1,3,6-trisulfonic acid and FACE is able to resolve each fraction as a discrete band depending on their M. After densitometric acquisition, the migration distance of each Hep standard is acquired and the third-grade polynomial calibration standard curve is determined by plotting the logarithms of the M values as a function of migration ratio. Purified Hep samples having different properties, pharmaceutical Heps and various LMW-Heps were analyzed by both FACE and conventional high-performance size-exclusion liquid chromatography (HPSEC) methods. The molecular weight value on the top of the chromatographic peak (Mp), the number-average Mn, weight-average Mw and polydispersity (Mw/Mn) were examined by both techniques and found to be similar. This approach offers certain advantages over the HPSEC method. The derivatization process with 8-aminonaphthalene-1,3,6-trisulfonic acid is complete after 4 h so that many samples may be analyzed in a day also considering that multiple samples can be run simultaneously and in parallel and that a single FACE analysis requires approx. 15 min. Furthermore, FACE is a very sensitive method as it requires approx. 5-10 microg of Heps, about 10-100-fold lower than samples and standards used in HPSEC evaluation. Finally, the utilization of mini-gels allows the use of very low amounts of reagents with neither expensive equipment nor any complicated procedures having to be applied. This study demonstrates that FACE analysis is a sensitive method for the determination of the M values of Heps and LMW-Heps with possible utilization in virtually any kind of research and development such as quality control laboratories due to its rapid, parallel analysis of multiple samples by means of common and simple largely used analytical laboratory equipment.

Capillary electrophoresis determination of glucosamine in nutraceutical formulations after labeling with anthranilic acid and UV detection

A new robust CE method for the determination of the glucosamine (GlcN) content in nutraceutical formulations is described after its derivatization with anthranilic acid (2-aminobenzoic acid, AA). The CE separation of derivatized GlcN with AA was performed on an uncoated fused-silica capillary tube (50 microm I.D.) using an operating pH 7.0 buffer of 150 mM boric acid/50 mM NaH2PO4 and UV detection at 214 nm. The method was validated for specificity, linearity, accuracy, precision, limit of detection (LOD), and limit of quantitation (LOQ). The detector response for GlcN was linear over the selected concentration range from 240 to 2400 pg (40-400 microg/mL) with a correlation coefficient greater than 0.980. The intra- and inter-day variations (CV%) were between 0.5 and 0.9 for migration time, and between 2.8 and 4.3 for peak area, respectively. The LOD and the LOQ of the method were approximately 200 and 500 pg, respectively. The intra- and inter-day accuracy was estimated to range from 2.8% to 5.1%, while the percent recoveries of GlcN in formulations were calculated to be about 100% after simple centrifugation for 10 min, lyophilization and derivatization with AA. The CE method was applied to the determination of GlcN content, in the form of GlcN-hydrochloride or GlcN-sulfate, of several nutraceutical preparations in the presence of other ingredients, i.e. chondroitin sulfate, vitamin C and/or methylsulfonylmethane (MSM) as well as salts and other agents. The quantitative results obtained were in total conformity with the label claims.

Eosinophilia-associated muscle disorders: an immunohistological study with tissue localisation of major basic protein in distinct clinicopathological forms

Aims:

(a) To evaluate tissue eosinophil density, location of eosinophil cytotoxic products, histopathological muscle changes and inflammatory cell types in different eosinophilia-associated myopathies that are clinicopathologically heterogeneous. (b) To determine the immunohistological range of tissue eosinophil density in non-eosinophilic inflammatory myopathies.

Methods:

Muscle biopsy specimens from seven patients with blood and/or tissue eosinophilia and clinicolaboratory myopathic signs (five chronic course myopathies, one subacute onset fasciitis/myositis, one acute myositis), and from 18 non-eosinophilic inflammatory myopathies, underwent routine staining, inflammatory infiltrate immunophenotyping, immunostaining for eosinophil major basic protein (MBP) and transmission electron microscopy examination. Eosinophil and total inflammatory cell counts were statistically analysed.

Results:

Histological examination showed occasional or no infiltrating eosinophils in all cases. MBP staining showed that tissue eosinophil density and percentages in eosinophilia-associated myopathies were significantly higher than in idiopathic myositides. Extracellular MBP diffusion, the hallmark of eosinophil cytotoxicity, was recurrent on sarcolemma and endothelium. Electron microscopy showed eosinophils close to sarcolemma, abundant mast cells, and capillary endothelial swelling. Immunostaining detected a higher mean eosinophil density in idiopathic myositides than previously assessed histologically.

Conclusions:

MBP immunohistology on skeletal muscle, previously performed only for acute eosinophilic polymyositis, suggests that eosinophil-mediated injury of muscle cells may occur in a wider spectrum of less aggressive eosinophilia-associated myopathies than previously thought. As conventional histology is likely to underestimate this leucocyte subset, MBP staining may be a useful tool in the analysis of tissue infiltration of eosinophils as a possible treatment target.

Capillary blotting of glycosaminoglycans on nitrocellulose membranes after agarose-gel electrophoresis separation

A method for the blotting and immobilizing of several nonsulfated and sulfated complex polysaccharides on membranes made hydrophilic and positively charged by cationic detergent after their separation by conventional agarose gel electrophoresis is illustrated. This new approach to the study of glycosaminoglycans (GAGs) utilizes the capacity of agarose gel electrophoresis to separate single species of polysaccharides from mixtures and the membrane technology for further preparative and analytical uses.Nitrocellulose membranes are derivatized with the cationic detergent cetylpyridinium chloride and mixtures of GAGs are capillary blotted after their separation in agarose gel electrophoresis. Single purified species of variously sulfated polysaccharides are transferred on derivatized membranes with an efficiency of 100% and stained with alcian blue (irreversible staining) and toluidine blue (reversible staining). This enables a lower amount limit of detection of 0.1 microg. Nonsulfated polyanions, for example hyaluronic acid, may also be transferred to membranes with a limit of detection of approximately 0.1-0.5 microg after irreversible or reversible staining. The membranes may be stained with reversible staining and the same lanes are used for immunological detection or other applications.

Micellar electrokinetic capillary chromatography determination of alginic acid in pharmaceutical formulations after treatment with alginate lyase and UV detection

A new highly specific and sensitive capillary electrophoresis method (electrokinetic chromatography with SDS) for the determination of the total alginic acid (AA) content in pharmaceutical formulations is described by means of capillary electrophoresis at 230 nm after treatment with alginate lyase [4.2.2.3] and separation of unsaturated products, Delta-oligomers (DeltaHexA-[HexA](n)), in particular, DP3 (DeltaHexA-HexA-HexA) and DP4 (DeltaHexA-HexA-HexA-HexA). Using a buffer constituted with 10 mM sodium borate and 50 mM SDS at pH 9.0, micellar electrokinetic capillary chromatography was able to determine with very high resolution the AA Delta-oligomers produced by the action of the lyase (mainly DP3 and DP4) as one single species. The intra- and inter-day variations (CV%) were between 6.3 and 9.1 for migration time and between 2.5 and 5.7 for peak area, respectively. The calibration curve showed good linearity for the examined concentration range (60-360 ng) with an average correlation coefficient greater than 0.980. The lowest detection limit and the lowest quantitation limit of the method were 15 ng (0.25 mg/mL) and 40 ng (0.67 mg/mL), respectively. The intra- and inter-day variations in terms of CV% were 5.5 and 8.6%, respectively, and the intra- and inter-day accuracy was estimated to range from 4.1 to 8.9%, while the percent recoveries of AA were calculated to be 102, 97 and 93% for different AA amounts. Variations in temperatures, voltage and buffer composition in comparison with adopted conditions within a 10% limit do not modify the electrophoresis results. The evaluation of AA was performed in both solid and liquid pharmaceutical formulations also in the presence of other ingredients, in particular, aluminium, sodium and potassium bicarbonate, and emulsifying and flavouring agents. The quantitative results obtained were 101.2+/-3.4% of AA content in tablets and 98.4+/-2.8% in liquid formulation, in total conformity with the label claims.

Mass spectrometry for the characterization of unsulfated chondroitin oligosaccharides from 2-mers to 16-mers. Comparison with hyaluronic acid oligomers

This study reports for the first time the complete liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS) and tandem mass spectrometry (MS/MS) analyses performed in negative ion mode of saturated unsulfated chondroitin oligosaccharides up to 16-mers and comparison with hyaluronic acid (HA) oligomers differing only in the nature of the hexosamine residue. MS/MS of the chondroitin disaccharide on the singly charged precursor at m/z 396.1 afforded a glycosidic cleavage C1 product ion at m/z 192.9. In the tetrasaccharide, C2 (m/z 396.0) and C3 (m/z 572.0) product anions were generated by glycosidic cleavage. A C5 [M-2H]2- product ion at m/z 475.1 was generated by the glycosidic cleavage of the hexasaccharide, and a C7 ion (m/z 664.6, charge state of -2) was produced from the octasaccharide. The same fragmentation pattern of deprotonated oligomers was observed for the largest oligosaccharides, from 10- to 16-mers. There has been no previous report of MS/MS spectra for unsulfated chondroitin oligomers of these sizes. Unsulfated saturated chondroitin oligosaccharides with x-mer units and larger than a tetrasaccharide dissociate to almost exclusively form CX-1-type ions. Saturated HA oligomers also afforded the same fragmentation pattern as deprotonated oligomers by ESI-MS and MS/MS analyses. Thus, under the experimental conditions used in the current study, we were unable to distinguish between unsulfated chondroitin and HA.

Capillary electrophoresis of complex natural polysaccharides

Complex natural polysaccharides, glycosaminoglycans (GAGs), are a class of ubiquitous macromolecules that exhibit a wide range of biological functions and participate and regulate multiple cellular events and (patho)physiological processes. They are generally present either as free chains (hyaluronic acid and bacterial acidic polysaccharides) or as side chains of proteoglycans (PGs; chondroitin/dermatan sulfate, heparin/heparan sulfate, and keratan sulfate) and are most often found in cell membranes and in the extracellular matrix. The recent emergence of modern analytical tools for their study has produced a virtual explosion in the field of glycomics. CE, due to its high resolving power and sensitivity, has been useful in the analysis of intact GAGs and GAG-derived oligosaccharides and disaccharides affording concentration and structural characterization data essential for understanding the biological functions of GAGs. In this review, novel off-line and on-line CE-MS and MS/MS methods for screening of GAG-derived oligosaccharides and disaccharides will be discussed.

Lymphatic vessels in human eyelids: an immunohistological study in dermatochalasis and chalazion

We investigated lymphatic morphology and expression of endothelin (ET-1) axis molecules in human eyelids affected by an inflammatory state (chalazion) and an age-related degenerative condition (dermatochalasis). Lymphatics were immunohistologically detected by D2-40/LYVE-1 staining. Absorbing lymphatic vessels were localized in papillary dermis and around skin appendages with distinctive morphology. In chalazion, D2-40 reactive flattened lymphatic profiles were compressed by inflammatory infiltrate; in dermatochalasis, large fully opened lymphatics were observed, with a significantly wider total area (lymphatic lumina/200x field; p < 0.05). The lymphatic density (number/200x field) in the two groups was within the same range. Lymphatic dilation is possibly dependent on reduction and fragmentation of the dermal elastic network as well as of oxytalanic fibers in the papillary dermis of dermatochalasis, as shown by Weigert's reaction. Multifunctional peptide ET-1, involved in vasomotion, inflammation and connective proliferation, was faintly and discontinuously localized on lymphatics, as was its type A receptor. In contrast, the consistent expression of type B receptor indicates that lymphatic endothelium is a physiological target for ET-1, whose effects are modulated by multiple pathophysiological conditions. Thus, vasoactive factors play a role in the physiology of richly vascularized eyelids, and therefore, morphofunctional characterization of lymphatic vessels may be useful in suggesting treatment options.

Analytical aspects of pharmaceutical grade chondroitin sulfates

Chondroitin sulfate is a very heterogeneous polysaccharide in terms of relative molecular mass, charge density, chemical properties, biological and pharmacological activities. It is actually recommended by EULAR as a symptomatic slow acting drug (SYSADOA) in Europe in the treatment of knee osteoarthritis based on meta-analysis of numerous clinical studies. Chondroitin sulfate is also utilized as a nutraceutical in dietary supplements mainly in the United States. On the other hand, chondroitin sulfate is derived from animal sources by extraction and purification processes. As a consequence, source material, manufacturing processes, the presence of contaminants, and many other factors contribute to the overall biological and pharmacological actions of these agents. The aim of this review is to evaluate new possible more specific analytical approaches to the determination of the origin and purity of chondroitin sulfate preparations for pharmaceutical application and in nutraceuticals, such as the evaluation of the molecular mass values, the constituent disaccharides, and the specific and sensitive agarose-gel electrophoresis technique. Furthermore, a critical evaluation is presented, together with a discussion of the limits of these analytical approaches. Finally, the necessity for reference standards having high specificity, purity and well-known physico-chemical properties useful for accurate and reproducible quantitative analyses will be discussed.

Chondroitin C lyase [4.2.2.] is unable to cleave fructosylated sequences inside the partially fructosylated Escherichia coli K4 polymer

Chondroitin C lyase was demonstrated to be unable to act on fructosylated sequences inside a partially fructosylated polysaccharide having the chondroitin backbone structure, the Escherichia coli K4 polymer, using different analytical approaches. Chondroitin C lyase produced various unsaturated oligosaccharides by acting on an approximately 27%-fructosylated K4 polymer. The online HPLC-ESI-MS approach showed the disaccharide nature of the main species produced by chondroitinase C as DeltaHexA-GalNAc. Furthermore, the non-digested sequences inside the K4 polymer were demonstrated to be oligosaccharides bearing a fructose for each glucuronic acid unit. In fact, unsaturated fully fructosylated oligomers, from tetrasaccharide to decasaccharide (DeltaHexA(Fru)-GalNAc-[GlcA(Fru)-GalNAc](n) with n between 1 and 4), at decreasing percentages, were produced by the enzyme. These results clearly indicate that chondroitinase C cleaved the innermost glucuronic acid-N-acetylgalactosamine linkage without affecting the 1,4 glycosidic linkage between fructosylated glucuronic acid and N-acetylgalactosamine residues, confirming that the 3-O-fructosylation of the GlcA residue renders the polysaccharide resistant to the enzyme action. This novel specific activity of chondroitinase C was also useful for the production of discrete microgram amounts of fully fructosylated oligomers, from 4- to 10-mers, from E. coli K4 for possible further studies and applications.

Endothelin-1 and endothelin-converting enzyme-1 in human granulomatous pathology of eyelid: an immunohistochemical and in situ hybridization study in chalazia

Endothelin-1 (ET-1), a potent vasoconstrictor peptide, is involved in several functions of eye pathophysiology, such as regulation of intraocular tension and retinal reactive vasoconstriction. As ET-1 pro-inflammatory and fibrosing activity is emerging in different fields of pathology, we investigated the expression of ET-1 and endothelin-converting enzyme-1 (ECE-1) in chalazia, granulomatous lesions of the eyelid. ET-1 and ECE-1 were analyzed by immunohistochemistry (IHC) in twenty surgically removed chalazia, with regard to expression in eyelid structures and inflammatory infiltrate. Phenotype of ET-1 expressing inflammatory cells was established by double immunofluorescence. The cellular localization of prepro-ET-1 (pp-ET-1) mRNA and ECE-1 mRNA was studied by nonisotopic in situ hybridization (ISH). Neutrophils (PMNs), macrophages and T-lymphocytes were scattered in stroma, around alveoli and grouped in lipogranulomas. PMNs, macrophages, basal epithelium of meibomian adenomers and central ducts immunostained for ET-1. ECE-1 protein was found in meibomian adenomers, conjunctival epithelium, tarsal mucous glands and in inflammatory cells. Hybridization signals for pp-ET-1 mRNA and ECE-1 mRNA were recognized in healthy and degenerating meibomian ducts, adenomers, inflammatory cells, as well as in vessel walls. ECE-1 mRNA was also present in conjunctival epithelium and Henle's crypts. Our findings suggest that the multifunctional peptide ET-1 may have a role in molecular genesis of tissue damage in chalazia. ET-1 cytokine activity is likely to support the migration of inflammatory cells and the setting of lipogranulomas; ET-1 stimulation might contribute to proliferation of fibroblasts and collagen synthesis. ET-1 upregulation on meibomian adenomers and ducts may further enhance granulomas formation by stimulating lipid release.

Degradation of high-molar-mass hyaluronan by an oxidative system comprising ascorbate, Cu(II), and hydrogen peroxide: Inhibitory action of antiinflammatory drugs—Naproxen and acetylsalicylic acid

Changes in dynamic viscosity of the solutions of a high-molar-mass hyaluronan (HA) were monitored using a rotational viscometer. The degradative conditions generated in the HA solutions by a system comprising ascorbate plus Cu(II) plus H(2)O(2) were studied either in the presence or absence of a drug--naproxen or acetylsalicylic acid. Continual decrease of the dynamic viscosity of HA solution was indicative of the polymer degradation. Addition of the drug retarded/inhibited the HA degradation in a concentration-dependent manner. The characteristics of the fragmented polymers were investigated by FT-IR spectroscopy and by two different liquid chromatographic techniques, namely by size-exclusion chromatography equipped with a multi-angle light scattering photometric detector and by high-performance liquid chromatography connected on-line to a spectrofluorometer.

Fine characterization of mitral valve glycosaminoglycans and their modification with degenerative disease

BACKGROUND

The levels and fine structure of complex polysaccharides, glycosaminoglycans (GAGs), were determined in segments of the posterior mitral valve leaflet (MVL) taken from 15 patients affected by mitral regurgitation and degenerative disease and were compared with segments from 15 multiorgan donors.

METHODS

MVL GAGs were analyzed by agarose gel electrophoresis, and by HPLC and fluorophore-assisted carbohydrate electrophoresis to evaluate disaccharide patterns after treatment with chondroitinase ABC.

RESULTS

GAGs from the control group were composed of approximately 37% hyaluronic acid and 63% chondroitin sulfate/dermatan sulfate with a charge density of approximately 0.61. Chondroitin sulfate/dermatan sulfate polymers contained approximately 23% of the disaccharide sulfated in position 6 on N-acetyl-galactosamine, approximately 38% of the 4-sulfated disaccharide and approximately 2% of the non-sulfated disaccharide (with a 4-sulfated/6-sulfated ratio of 1.7). The total amount of GAGs was 0.66 microg/mg tissue. The total amount of GAGs in patients suffering from mitral regurgitation and degenerative disease was approximately 51.5% higher (although the difference was not significant, probably because of the low number of subjects enrolled in the study). However, significantly higher hyaluronic acid content (approx. +38%, p<0.05) and lower sulfated GAG content (approx. -21%, p<0.005) were demonstrated. As a consequence, the total charge density decreased by approximately 23% (p<0.005). This macro-modification of GAG composition was also followed by a micro-alteration of the structure of the sulfated polysaccharides, in particular with a significant decrease in the 4-sulfated disaccharide (and a parallel increase in hyaluronic acid content) with no modification of the percentage of the 6-sulfated and non-sulfated disaccharides (with a significant decrease in the 4-/6-sulfated ratio).

CONCLUSIONS

We assume that changes in the relative amount and distribution of GAGs in posterior MVL in subjects suffering from mitral regurgitation and degenerative disease are consistent with a decrease in the tension to which these tissues are subjected and with an abnormal matrix microstructure capable of influencing the hydration and of conditioning the mechanical weakness of these pathological tissues.

On-line HPLC/ESI-MS separation and characterization of hyaluronan oligosaccharides from 2-mers to 40-mers

A new method for the separation and identification of oligosaccharides obtained by enzymatic digestion of hyaluronic acid (HA) with hyaluronidase (EC 3.2.1.35) using on-line high-performance liquid chromatography/electrospray mass spectrometry (HPLC/ESI-MS) is presented. Reversed-phase ion pairing-HPLC, based on tributylamine salts and a volatile mobile phase, provided excellent chromatographic resolution and separation was achieved for HA oligosaccharides containing 2-40 monomers (from 2- to 40-mers). Using the on-line ion trap mass analyzer, complete identification and structural information for each HA oligomer species was obtained. In particular, a series of negatively charged species of different m/z ratios are seen for each oligosaccharide. Smaller HA species, from 2- to 4-mers, exhibit mainly [M-H](-1) anions, whereas the 6-10-mers exist predominantly as the charge state of -2. The HA oligomers from 12- to 18-mers are mainly represented by [M-3H](-3) anions while species from 20- to 28/30-mers are characterized by a charge state of -4. HA oligosaccharides from 32- to 40-mers exist as [M-5H](-5) anions. Furthermore, for smaller HA species, from 4/6- to 18/20-mers, ESI-MS revealed, generally in low relative abundance, anions related to the loss of one/two monosaccharide unit(s) from the oligomers, and no odd-numbered anions were produced for HA species greater than 20-mers.

Mobilization of osmotically inactive Na+ by growth and by dietary salt restriction in rats

The idea that an osmotically inactive Na(+) storage pool exists that can be varied to accommodate states of Na(+) retention and/or Na(+) loss is controversial. We speculated that considerable amounts of osmotically inactive Na(+) are lost with growth and that additional dietary salt excess or salt deficit alters the polyanionic character of extracellular glycosaminoglycans in osmotically inactive Na(+) reservoirs. Six-week-old Sprague-Dawley rats were fed low-salt (0.1%; LS) or high-salt (8%; HS) diets for 1 or 4 wk. At their death, we separated the tissues and determined their Na(+), K(+), and water content. Three weeks of growth reduced the total body Na(+) content relative to dry weight (rTBNa(+)) by 23%. This "growth-programmed" Na(+) loss originated from the bone and the completely skinned and bone-removed carcasses. The Na(+) loss was osmotically inactive (45-50%) or osmotically active (50-55%). In rats aged 10 wk, compared with HS, 4 wk of LS reduced rTBNa(+) by 9%. This dietary-induced Na(+) loss was osmotically inactive ( approximately 50%) and originated largely from the skin, while approximately 50% was osmotically active. LS for 1 wk did not reduce skin Na(+) content. The mobilization of osmotically inactive skin Na(+) with long-term salt deprivation was associated with decreased negatively charged skin glycosaminoglycan content and thereby a decreased water-free Na(+) binding capacity in the extracellular matrix. Our data not only serve to explain discrepant results in salt balance studies but also show that glycosaminoglycans may provide an actively regulated interstitial cation exchange mechanism that participates in volume and blood pressure homeostasis.

Mass spectrometry characterization of Escherichia coli K4 oligosaccharides from 2-mers to more than 20-mers

The separation and characterization of oligosaccharides obtained by hyaluronidase [E.C. 3.2.1.35] digestion of Escherichia coli K4 polysaccharide using online high-performance liquid chromatography/electrospray ionization mass spectrometry (HPLC/ESI-MS) are presented. Complete identification and structural information for oligosaccharides containing 2-24 monomers (from 2- to 24-mers) were obtained. In particular, smaller K4 species, from 2-mers to 4-mers, exhibited mainly [M-H](-1) anions, whereas the 6- to 8-mers existed predominantly at the charge state of -2. The K4 oligomers from 10-mers to 14-mers were mainly represented by [M-3H](-3) anions while species from 16- to 20-mers were characterized by a charge state of -4. K4 oligosaccharides from 22- to 24-mers existed as [M-4H](-4) and [M-5H](-5) anions and, for this latter species, ions having a charge state of -6 appeared. For smaller K4 species, in particular from 6-mers to 10-mers, ESI-MS revealed anions related to the loss of one monosaccharide unit from the oligomers due to apparent collisional activation and ion source fragmentation. However, no odd-numbered anions were produced for K4 2/4-mer species or for oligosaccharides greater than 12-mers, while for K4 species 8/10-mer, ESI-MS revealed odd-numbered anions generally in low relative abundance making the interpretation of the spectra easier. The ESI-MS spectra of oligosaccharides separated by online HPLC were applied to the evaluation of the K4 polymerization process, confirming that the addition of fructose units is not critical for chain elongation as variously fructosylated oligomer species were detected directly on the K4 carbohydrate backbone.

Lymphatic vessels in human sural nerve: immunohistochemical detection by D2-40

Lymphatics were detected in the epineurium of the human sural nerve by D-240 immunostaining and confirmed by ultrastructural examination.

Therapeutic applications of glycosaminoglycans

Complex polysaccharides, hyaluronic acid or hyaluronan (HA), keratan sulfate (KS), chondroitin sulfates (CSs) and heparin (Hep)/heparan sulfate (HS), are a class of ubiquitous molecules exhibiting a wide range of biological functions. They are widely distributed as glycosaminoglycans (GAGs) sidechains of proteoglycans (PGs) in the extracellular matrix and at cellular level. The recent emergence of improved enzymatic and analytical tools for the study of these complex sugars has produced a virtual explosion in the field of glycomics. In particular, the study of the GAG family of polysaccharides has shed considerable light on the way in which specific carbohydrate structures modulate cellular phenotypes. In addition to the well-known therapeutic applications of some of these macromolecules, such as HA and derivatives as structure modifying molecules and possessing gel-like properties able to provide functional support for tissues, Hep as an anticoagulant and antithrombotic drug and CS in the treatment of osteoarthritis (OA), this increased understanding of GAG structure-function relationship has led to the discovery of novel pharmaceuticals for the possible treatment of serious diseases, such as cancer. In this paper, the structure and the therapeutic applications of several complex natural polysaccharides, including HA, CS/DS, Hep and their derivatives, are presented and discussed also in the light of the many questions still left unanswered, such as improved preparation and GAG-based drugs with improved properties and new possible therapeutic applications.