The structure and metabolism of mucopolysaccharides (glycosaminoglycans) and the problem of the mucopolysaccharidoses

The basic science of human knee menisci: structure, composition, and function

CONTEXT

Information regarding the structure, composition, and function of the knee menisci has been scattered across multiple sources and fields. This review contains a concise, detailed description of the knee menisci-including anatomy, etymology, phylogeny, ultrastructure and biochemistry, vascular anatomy and neuroanatomy, biomechanical function, maturation and aging, and imaging modalities.

EVIDENCE ACQUISITION

A literature search was performed by a review of PubMed and OVID articles published from 1858 to 2011.

RESULTS

This study highlights the structural, compositional, and functional characteristics of the menisci, which may be relevant to clinical presentations, diagnosis, and surgical repairs.

CONCLUSIONS

An understanding of the normal anatomy and biomechanics of the menisci is a necessary prerequisite to understanding the pathogenesis of disorders involving the knee.

Chitosan-chondroitin sulphate nanoparticles for controlled delivery of platelet lysates in bone regenerative medicine

In this study, a new formulation of nanoparticles (NPs) based on the electrostatic interaction between chitosan and chondroitin sulphate (CH-CS NPs) is proposed for the controlled release of proteins and growth factors (GFs), specifically platelet lysates (PLs). These nanoparticulate carriers are particularly promising for protein entrapment because the interactions between the polysaccharides and the entrapped proteins mimic the interactions between chondroitin sulphate and proteins in the native extracellular matrix (ECM). Spherical non-cytotoxic NPs were successfully produced, exhibiting high encapsulation efficiency for physiological levels of GFs and a controlled protein release profile for > 1 month. Moreover, it was also observed that these NPs can be uptaken by human adipose-derived stem cells (hASCs), depending on the concentration of NPs in the culture medium and incubation time. This shows the versatility of the developed NPs, which, besides acting as a protein delivery system, can also be used in the future as intracellular carriers for bioactive agents, such as nucleotides. When the PL-loaded NPs were used as a replacement of bovine serum for in vitro hASCs culture, the viability and proliferation of hASCs was not compromised. The release of PLs from CH-CS NPs also proved to be effective for the enhancement of in vitro osteogenic differentiation of hASCs, as shown by the increased levels of mineralization, suggesting not only the effective role of the delivery system but also the role of PLs as an osteogenic supplement for bone tissue engineering and regenerative medicine applications.

Targeted delivery of oligonucleotides into tumor-associated macrophages for cancer immunotherapy

Tumor-associated macrophages (TAMs) have been proven to be a driving force in the initiation, proliferation, metastasis and angiogenesis of various tumors. Specifically, alterations in the functions of TAMs exhibited inhibitory effects on tumor growth. However, there is currently no research being conducted on the targeting delivery of drugs into TAMs for cell-specific tumor immunotherapy. In the present study, we developed a TAMs targeted delivery system that is triggered by the acidic microenvironment in the tumor to release a TAMs-recognizing nano-complex loaded with oligonucleotides. By using this system, we demonstrated a significant anti-tumor effect of an oligonucleotide combination of CpG oligonucleotide, anti-IL-10 and anti-IL-10 receptor oligonucleotides. These nucleic acid drugs delivered by the delivery system accumulated in the TAMs of an allograft hepatoma murine model by intravenous injection, suppressed the pro-tumor functions and stimulated the anti-tumor activities of TAMs. More importantly, the nucleic acid drug-based immune-regulation was restricted to the tumor microenvironment and did not cause an upregulation of serum inflammatory cytokines. Our present study provides an effective therapeutic strategy for regulating cell-specific functions using nucleic acid drugs.

Serum N-acetyl-beta-D-gulucosaminidase activity increases in association with insulin resistance in patients with coronary artery disease

N-acetyl-beta-D-glucosaminidase (NAG) is released from lysosomes, but the clinical significance of its serum activity in the pathogenesis of coronary artery disease has not been well understood. We measured serum NAG activity by a colorimetric method in consecutive 168 patients suspected of having coronary artery disease who underwent diagnostic coronary angiography. In addition, we evaluated the relationship between the activity and severity of coronary artery disease, as well as various coronary risk factors. Serum NAG activity was higher in the multi-vessel disease group than in the no stenotic lesion group (9.2+/-2.3 vs. 7.8+/-1.8 U/l, P<0.01) and in the single-vessel disease group (vs. 8.2+/-2.2 U/l, P<0.05). In all patients, Gensini score was closely correlated with the serum NAG activity (r = 0.39, P<0.001). Multiple regression analysis showed that serum NAG activity was correlated with plasma insulin level (r = 0.49, P<0.01), but not correlated with other coronary risk factors. In 126 patients without apparent diabetes mellitus, serum NAG was also correlated with plasma insulin level (r = 0.37, P<0.01) and additionally with insulin resistanc determined by homeostasis model assessment (r = 0.47, P<0.01). Our results suggested that serum NAG activity correlates with the severity of coronary artery disease in relation to plasma insulin level and insulin resistance, and thus can be an indicator of coronary artery disease based upon abnormalities of glucose metabolism.

Proteoglycans in the pathogenesis of Alzheimer's disease and other amyloidoses

Proteoglycans and the amyloid P component are two constituents of amyloid that appear to be present regardless of the type of amyloid protein deposited, the extent of amyloid deposition and the tissue or organ involved. This article reviews the literature concerning proteoglycans and/or glycosaminoglycans in amyloidosis and describes recent studies which demonstrate their localization to the characteristic lesions of Alzheimer's disease and the amyloid plaques containing PrP protein in the prion diseases. Additionally, the possible interaction of proteoglycans with various amyloidogenic proteins, including the beta-amyloid protein in Alzheimer's disease is discussed. It is postulated that proteoglycans localized to a number of different amyloids play a common role in the pathogenesis of amyloidosis. Some of these hypothesized roles include 1) inducing amyloidogenic precursor proteins to form amyloid fibrils containing a predominant beta-pleated sheet structure, 2) influencing amyloid deposition to occur at specific anatomical sites within tissues and/or 3) aiding in prevention of amyloid degradation once amyloid has formed.

Histochemical demonstration of cytoplasmic glycosaminoglycans in the macroneurons of the human central nervous system

The presence of glycosaminoglycans (GAG) has been histochemically demonstrated in the CNS of various mammalian species. They have been related with some nerve functions as neurotransmitters storage and synaptic transmission. In the present paper, the histochemical properties of nerve cell cytoplasmic GAG were studied in several regions of adult human CNS. Samples of brain cortex, pons, upper medulla, and cerebellar cortex obtained by autopsy from subjects not dying after neurological diseases were fixed by immersion in glutaraldehyde, dehydrated with ethanol, and embedded in paraffin. The sections were stained with Alcian blue solutions adjusted to pH 2.5, 4.0, and 5.7. To the latter solution MgCl2 was added in increasing concentration from 0.05 to 1.2 M. Testicular hyaluronidase, neuraminidase, and ribonuclease were applied on simultaneous sections with their respective controls. The sequence of these reactions allowed us to demonstrate the presence of hyaluronic acid along chondroitin-4- and/or 6-sulphate in the cytoplasm of most nerve cells. The sulphated GAG showed certain variability in the various regions studied related specially with their grade of sulphation.

Familial progressive myoclonic epilepsy. A clinical, genetical, biochemical and patho-anatomical study of a family with a 6-year follow-up

Six siblings, including 4 cases of myoclonic epilepsy, their parents and 2 grandmothers were subjected to systematic investigation, and the patients were followed-up. The genetic studies revealed in the mother's family a patient with Lafora bodies demonstrated at autopsy. No chromosome abnormalities were found nor any linkage to the HLA system. The affected family members were characterized biochemically by an increased excretion of total glycosaminoglycans and/or an abnormal electrophoretic pattern of urinary glycosaminoglycans with an increased proportion of low-sulfated glycosaminoglycans. In the healthy family members this pattern of electrophoresis could also be demonstrated in the father and the paternal grandmother. Based on the biochemical results and the genetic studies it is suggested that the family members with progressive familial myoclonic epilepsy present a combination of at least 2 hereditary defects. The course of the disease has been relatively benign and treatment with sodium valproate, baclofen and clonazepam has shown quite satisfying results. In consequence of the biochemical findings combined treatment with A and E vitamins has been initiated.

Mucopolysaccharidase activity and glycosaminoglycan content in traumatized resorbing deciduous teeth

The periodontal ligaments from traumatized deciduous teeth, while undergoing rapid resorption, were analyzed biochemically for mucopolysaccharidase activity and for total glycosaminoglycan content of dentin and cementum. Enzyme activity was present only in resorbing teeth. A concomitant 65 percent decrease in glycosaminoglycans from these teeth occurred as well.

Mucopolysaccharidase activity in traumatized human deciduous teeth undergoing accelerated resorption: isolation and characterization

Mucopolysaccharidase activity was observed in traumatized human decidous teeth. Histochemical analysis of the periodontal ligaments from these teeth revealed a loss of film substrate metachromasia during incubation, indicating enzyme activity. Routine histology of these ligaments showed the presence of an inflammatory infiltrate throughout this tissue. Biochemical analysis of the ligaments revealed a 10-fold increase of enzyme activity when incubation time was increased from 1 to 8 h. When compared to the enzyme activity measured during physiologic resorption, activity was increased. This suggests that the presence of an inflammatory infiltrate not observed in the tissues undergoing physiologic resorption may be responsible for the rapid resorption seen in traumatized deciduous teeth.

Extraction and characterization of proteoglycan from human meniscus

This study consists of (1) the extraction of proteoglycan from the human meniscus under dissociative conditions, (2) an investigation of the changes that occur in the abundance and structure of this proteoglycan with age and (3) a comparison of these findings with those for human articular-cartilage proteoglycan. Adult meniscus was found to possess proteoglycan molecules of similar size and glycosaminoglycan content to those present in cartilage, although tissue concentrations were considerably lower. In addition, age-related changes, with respect to the occurrence of keratan sulphate and the sulphation of chondroitin sulphate chains, were common to both tissues. The presence of aggregated proteoglycan was demonstrated, although specific interaction with hyaluronic acid was not conclusively shown biochemically. Differences were, however, noted in the structure of the proteoglycan between the two tissues: dermatan sulphate was found in the meniscus proteoglycan preparation and the core proteins exhibited some dissimilarities. A proteoglycan structure of this type would be compatible with its participation in meniscus elasticity, especially as the material is localized in a specific area.

Identification and localization of a mucopolysaccharidase in human deciduous teeth

The presence of a mucopolysaccharidase in resorbing deciduous teeth was investigated using histochemical techniques. The loss of toluidine blue metachromasia within glycosaminoglycan film substrates indicated the presence of enzyme activity, and was related to physiologic resorption. Such activity was localized to the periodontal ligament of these teeth.

Proteogylcan heterogeneity in embryonic chick articular and epiphyseal cartilages

Proteoglycans from two regions of the chick limb rudiment (articular and epiphyseal) were examined for chemical microheterogeneity. These cartilages are composed of at least two series of proteoglycan variants whose glycosaminoglycan side chains display microheterogeneity with respect to the proportions of 4- and 6-linked ester sulfate. Other differences are noted which are consonant with the hypothesis that extracellular matrix components may be structurally adapted to a tissue's developmental fate or function.

[Studies of the mucopolysaccharid metabolism in the juvenile angiofibroma (author's transl)]

The mucopolysaccharide content of juvenile angiofibromas is investigated using histochemical and ultrahistochemical methods (histochemical in ten cases, ultrahistochemical in four cases). The investigations result in typical histochemical features and show the localization of acid mucopolysaccharides at electronmicroscopical level. The endothelium of the vessels exhibits a strong PAS-reaction and also shows acid groups at the cell surfaces. The interstitial tissue demonstrates neutral perjodatreactive substances as well as acid mucopolysaccharides. The latter substances mainly reacted in perifibrillar position. Electronmicroscopically the perjodreactive material was localized in the cytoplasma of typical fibroblasts and their modulations resembling histiocytes. The acid groups of carboxylated and sulfated mucopolysaccharides of the intercellular substance could be determined as hyaluronic acides and chondroitinsulfates (Chondroitin-4 and Chondroitin-6 sulfate) using the critical-electrolyte-concentration method after Scott and Dorling. Ultrastructurally these acid groups are localized as cell coat covering the fibroblasts and between the collagen fibrils. This histochemical investigation also supports the thesis of an organoid growth pattern of juvenile angiofibroma.

The heart in the Hurler syndrome: gross, histologic and ultrastructural observations in five necropsy cases

Clinical and morphologic features of the cardiovascular system are described in five necropsy patients with the Hurler syndrome. In all five patients the coronary arteries, four cardiac valves, mural endocardium of all four chambers, myocardial walls and aorta were affected in a characteristic manner. All of these sites contained large clear cells known as Hurler cells (readily visible by light microscopy). In addition, granular cells were observed in semi-thin (1 mu) sections and by electron microscopy in the coronary arteries, atrioventricular (A-V) valves and in myocardial interstitium. These latter cells appear to produce collagen in an abnormal way and are probably responsible for the heavy deposits of collagen in the cardiovascular system of patients with the Hurler syndrome. In the cardiac muscle cells, in smooth muscle cells of the coronary arteries and in fibroblasts, wherever located, deposits of acid mucopolysaccharides and glycolipids usually were also observed. The acid mucopolysaccharide deposits were observed easily with light microscopy except in the cardiac muscle cells where they were seen only with electron microscopy. The glycolipid depositis, observed only on examination of 1 mu thick sections or with electron microscopy, have not previously been observed in coronary arteries or in myocardial cells. The infiltration into the heart by these cells and deposits in all five patients resulted in severe narrowing of the extramural coronary arteries, considerable thickening of the cardiac valves (the left-sided more than the right-sided valves), generalized thickening of mural endocardium and "stiffening" of the myocardial walls. Thus, the cardiovascular lesions in the Hurler syndrome are specific and life-threatening.

The mucopolysaccharidoses: inborn errors of glycosaminoglycan catabolism

The mucopolysaccharidoses are genetic disorders of glycosaminoglycan metabolism. Patients with these diseases accumulate within the lysosomes of most tissues excessive amounts of dermatan and/or heparan sulfates, or of keratan sulfate. The clinical consequences of such glycosaminoglycan storage range from skeletal abnormalities to cardiovascular problems, and to motor and mental retardation. In all mucopolysaccharidoses, except Morquio disease, an excessive accumulation of sulfate-labeled glycosaminoglycans has been demonstrated in fibroblasts cultured from the patient's skin. It was subsequently shown that this was due to the deficiency of specific proteins which were named "corrective factors", because their addition to the culture medium effected a normalization of the impaired glycosaminoglycan catabolism in the respective mucopolysaccharidosis fibroblasts. The investigation of the function of the corrective factors, and other studies, led to the identification of the enzymatic defect in each of the mucopolysaccharidoses. Seven lysosomal enzyme deficiencies are now recognized among this group of disorders. A classification of the diseases, according to the mutant gene products, reveals that there is considerable phenotypic variation not only between diseases, but also within several disease types. With the availability of the appropriate enzyme assays, the previous difficulties in diagnosing these disorders have now been overcome. Methods are also available for the prenatal diagnosis, and the detection of heterozygous individuals, in most of the mucopolysaccharidoses. Although correction of the metabolic defect through enzyme replacement has been achieved in tissue culture, many problems remain to be solved before such therapy may become applicable in the patients themselves.

Characterization of developing antler cartilage matrix. I. Selected histochemical and enzymatic assessment

Biopsy samples of the main beams and tines were obtained from the antlers of mature Rocky Mountain mule deer (Odocoileus hemionus hemionus) during the rapid phase of the antler grow-th cycle. The samples were studied using histochemical and enzymatic techniques for the demonstration of mucosubstances. The reserve mesenchyme contained chondroitin 4- and 6-sulfates, hyaluronic acid and sialic acid. During prechondroblastic and chondroblastic differentiation, some strongly sulfated mucopolysaccharides were complemented by low molecular weight or incompletely sulfated chondroitin 4- and 6-sulfates. During maturation of the cartilage strongly anionic mucopolysaccharides (possibly heparin, keratan and/or dermatan sulfates) were present in the general matrix and especially prominent along the capsular margins. Calcification foci, beginning initially in the mid-trabecular regions and eventually extending to the trabecular margins, were highly reactive for mucosubstances and were enzyme-resistant. This histochemical study establishes the cartilaginous nature of the developing deer antler, defines some of the mucosubstance constituents involved in the chondrogenic and calcification process, and confirms the utility of the antler as a model for chondrogenic and calcification studies.

The influence of age on the wound healing of experimental myocardial infarction in rats

In 6-weeks-old, 5-months-old and 21-months-old rats myocardial infarction was induced by coronary artery ligature. After performing the ligature the animals were administered 3H-thymidine, 3H-proline or 35S-sulphate at different times. The following parameters were determined: number of DNA- and tropocollagen-synthesizing connective tissue cells at the infarction border and at the infarction site; mean silver grain density above the nuclei or cells; duration of a cycle; number of mitoses, and incorporation of radioactive sulphate at the infarction site. In addition, the labelling and mitotic indices as well as the percentage of the standard deviation from the mean values were estimated. The following results were obtained: 1. The rate of granulation tissue formation in the necrotic zone is determined by the mitotic activity of the cells. With advancing age the cell cycles are being prolonged which results in retardation of wound healing. 2. The disturbed DNA-replication in old age is not associated with a time shift in the occurrence of the mitotic and labelling peaks. 3. With advancing age the number of fibroblasts synthesizing collagen precursors decreases. There exists no age-dependence of the 3H-proline incorporation rate, of the intracellular transport, of the synthesis of collagen precursor and of the release of labelled tropocollagen. In all age-groups under study these processes last approximately 4 hours. 4. Collagen fibre formation is accompanied by an increased synthesis of acid mucopolysaccharides. In infarction callosities the content of acid mucopolysaccharides mostly is constant. 5. The proliferating endothelial cells have a pronounced metabolic activity and a markedly short generation time.

Hyaluronic acid in cartilage and proteoglycan aggregation

1. Dissociation of purified proteoglycan aggregates was shown to release an interacting component of buoyant density higher than that of the glycoprotein-link fraction of Hascall & Sajdera (1969). 2. This component, which produced an increase in hydrodynamic size of proteoglycans on gel chromatography, was isolated by ECTEOLA-cellulose ion-exchange chromatography and identified as hyaluronic acid. 3. The effect of pH of extraction showed that the proportion of proteoglycan aggregates isolated from cartilage was greatest at pH4.5. 4. The proportion of proteoglycans able to interact with hyaluronic acid decreased when extracted above or below pH4.5, whereas the amount of hyaluronic acid extracted appeared constant from pH3.0 to 8.5. 5. Sequential extraction of cartilage with 0.15m-NaCl at neutral pH followed by 4m-guanidinium chloride at pH4.5 was shown to yield predominantly non-aggregated and aggregated proteoglycans respectively. 6. Most of the hyaluronic acid in cartilage, representing about 0.7% of the total uronic acid, was associated with proteoglycan aggregates. 7. The non-aggregated proteoglycans were unable to interact with hyaluronic acid and were of smaller size, lower protein content and lower keratan sulphate content than the disaggregated proteoglycans. Together with differences in amino acid composition this suggested that each type of proteoglycan contained different protein cores.

Mucopolysaccharides: comparison of chondroitin sulfate conformations with those of related polyanions

X-ray diffraction shows that chondroitin 6-sulfate, and some further rulfated derivatives, can occur in two ordered structures in stretched films. Both structures contain single helices with similar projected disaccharide lengths (9.6 and 9.8 angstroms) but with very different turn angles between successive disaccharides (120 and 45 degrees). In contrast, coaxial double helices of hyaluronates and t-carrageenates have shorter projected disaccharide lengths (8.5 and 8.9 angstroms).

A comparative study of the major glycoprotein isolated from normal and neoplastic gastric mucosa

The isolation and composition of glycoproteins from mucosae of normal stomachs, of stomachs with gastric ulcer, and of stomachs with carcinoma is described. The glycoproteins from the mucosae of normal stomachs and with gastric ulcer showed virtually the same carbohydrate and amino acid content as the principal gastric glycoprotein isolated from gastric aspirates. They all revealed a common basic carbohydrate composition: galactose, fucose, glucosamine, and galactosamine were present in approximate molar ratios of 4:3:3:1. THE RESULTS SUGGEST THAT THE GLYCOPROTEINS ISOLATED FROM GASTRIC ASPIRATES FROM NORMAL AND NEOPLASTIC GASTRIC MUCOSAE SHARE A NUMBER OF STRUCTURAL FEATURES: (1) a protein core with a characteristic amino acid composition; (2) the range of sugars forming the carbohydrate side chains; (3) galactosamine approximately equimolar with the sum of threonine and serine; (4) galactose approximately equimolar with the sum of glucosamine and galactosamine; (5) absence of mannose; (6) a high carbohydrate content (80-85%); and (7) blood group activity. The neoplastic glycoproteins differed from the normal glycoproteins in that the quantitative relationships of the carbohydrate components of the neoplastic glycoproteins showed variations dividing the extracts investigated into groups, each group with a distinctive and constant carbohydrate composition. The blood group specificity of 15 out of 24 cases investigated differed from that of the hosts' red cells.

Hurler's, Hunter's and Morquio's syndromes. A biochemical study in the light of current views of the underlying defects

Glycosaminoglycans were isolated from the urine of three patients with Hurler's, Hunter's and Morquio's syndromes and also from the liver and spleen of the case of Hurler's syndrome by a procedure avoiding further degradation. A method of determining the proportions of dermatan sulphate, heparan sulphate and chondroitin sulphate in each preparation is described. The relative proportions of these glycosaminoglycans in the urine and organs of the case of Hurler's syndrome were very similar. Glycosaminoglycans from the organs were of much lower molecular weight than normal, consisting of single chains of molecular weight about 5000 together with multiples of up to four such chains attached to peptide moieties. The linkage region normally attaching glycosaminoglycan chains to protein in whole protein-polysaccharides of connective tissue was degraded progressively towards serine. The total output and relative proportions of abnormal glycosaminoglycans in the urine were compared in two brothers with Hunter's syndrome examined on two occasions 4 years apart. At comparable ages they excreted about the same amount, and the relative proportions of each glycosaminoglycan remained essentially constant. The composition and chromatographic behaviour of the glycosaminoglycan in the urine from the case of Morquio's syndrome indicated that it consisted of material containing about one-third keratan sulphate and two-thirds chondroitin sulphate as part of the same molecule, as in proteoglycans of cartilage. The total output of glycosaminoglycans, although higher than normal, was considerably less than in other types of Mucopolysaccharidoses.