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PubMed1987

Urinary excretion of connective tissue metabolites under the influence of a new non-steroidal anti-inflammatory agent in adjuvant induced arthritis.

The therapeutic effect of boswellic acids and salai guggal in adjuvant induced arthritic rats in relation to urinary excretion of connective tissue metabolites viz. hydroxyproline, hexosamine and uronic acid was thoroughly investigated. Compared to controls, the arthritic animals showed an increase in the excretion of these metabolites in urine. The elevated levels of urinary hydroxyproline (free, total, nondialysable and dialysable), hexosamine and uronic acid in the arthritic animals were found to be slightly decreased in the acute phase and significantly decreased in the chronic phase of the disease following the administration of boswellic acids or salai guggal. The results of the investigation indicated that both these anti-inflammatory drugs could offer a partial protective action against changes induced by adjuvant induced arthritis.

Animals↗
PubMed1988

Studies on carbohydrate moieties of glycoproteins in established adjuvant induced arthritis.

The investigation presents the metabolic changes in the carbohydrate components of glycoproteins in several tissues of adjuvant arthritic rats. The experimental arthritis induces a significant modification of total carbohydrate moieties of glycoproteins in arthritic tissues. In both acute and chronic phases of the disease, the adjuvant arthritis caused a significant increase in the levels of carbohydrate moieties of tissue glycoproteins viz. total hexose, hexosamine, fucose, sialic acid, total neutral sugar content and neutral sugar monosaccharides. In addition, the urinary excretions of hexosamine and uronic acid in arthritic rats were found to be elevated significantly. The data from the investigation clearly indicate that the experimental arthritis induces an increased glycoprotein synthesis in most of the tissues examined.

Animals↗
PubMed1978

Changes in organic matrix of bone and of bone and blood ATP in rats fed rachitogenic diets.

Vitamin D deficient and phosphate deficient states were produced in young rats by the use of synthetic diets. Whole blood ATP, serum calcium and phosphorus and the ash, phospholipid, hexosamine and hydroxyproline contents of metaphyseal bones of control and rachitic rats were measured after 4 weeks on the diets. There was a decrease in whole blood ATP and serum phosphorus of the rachitic rats, and in the contents of ash, phospholipid and hexosamine of the rachitic metaphyses, while the hydroxyproline contents of the rachitic bones were higher than those of the controls. Subcutaneous injection of ATP or inorganic phosphate in rats, fed a low phosphate diet deficient in vitamin D, caused an increase in serum phosphorus and blood ATP levels and in metaphyseal ash contents. It is suggested that some of the metabolic disturbances in rickets are due to alteration in ATP production.

Adenosine Triphosphate↗
PubMed1995

Effects of Helicobacter pylori infection on gastric mucosal defense factors in Japanese monkeys.

The pathogenic role played by Helicobacter pylori in gastric mucosal defense was investigated in Japanese monkeys infected with H. pylori. Serum gastrin levels and ammonia concentrations in gastric juice were compared in H. pylori-infected (n = 6) and control (n = 7) groups. The gastritis score, the intracellular content of periodic acid-Schiff (PAS)-positive substance and hexosamine, and the bromodeoxyuridine (BrdU) labeling index in the gastric mucosa were compared in the two groups in the antrum and the corpus. The ammonia concentration in the gastric juice was significantly higher in the infected group (P < 0.01). The gastritis scores were significantly higher in the antrum and corpus in the infected group (P < 0.01, and P < 0.05, respectively). The content of PAS-positive substance and hexosamine was significantly decreased in the antrum of the infected group compared with that in the controls (P < 0.01, and P < 0.05, respectively), but there was no significant difference between the two groups in the corpus. The BrdU labeling indices were significantly higher in the antrum and corpus of the infected group (P < 0.01, and P < 0.01, respectively). Colonization by H. pylori injures the gastric mucosa by depressing the gastric mucosal defense factors, and, consequently, the cell kinetics are accelerated.

Ammonia↗
PubMed1985

Mineral and matrix alterations in the bones of incisors-absent (ia/ia) osteopetrotic rats.

The bones of incisors-absent (ia/ia) osteopetrotic rats differ from those of their normal littermates (ia/+) in histologic and radiographic appearance and in mechanical properties. This study examined how the mineral and matrices of osteopetrotic metaphyses and calvaria differed from normal controls. Bones of 11-day-old and 52-day-old osteopetrotic animals had higher ash (mineral) contents that age-matched controls; osteopetrotic metaphyses had elevated hexosamine contents, indicative of the persistence of cartilage. Calcium acidic phospholipid phosphate complexes, involved in initiation of hydroxyapatite formation in vivo and in vitro, were significantly reduced in content in all osteopetrotic bones. These results suggest that in the osteopetrotic rat, where osteoclast activity is defective, new mineral formation is reduced and replaced by accretion of mineral on existing crystals. Fractionation of osteopetrotic bone particles by density centrifugation demonstrated that the osteopetrotic bone was much more mineralized than that of age-matched controls. X-ray diffraction analysis of the mineralized fractions indicated a lack of growth of mineral crystals during maturation of the osteopetrotic animals. The absence of remodeling was apparent from the elevated Ca:P ratios of the highly mineralized osteopetrotic bone fractions, and from the high hexosamine content of these dense fractions. These observations may explain some of the unusual mechanical properties of osteopetrotic bone.

Animals↗
PubMed1994

Glycosaminoglycan composition of uninjured skin and of scar tissue in fetal, newborn and adult sheep.

Few details are available on the heterogeneity of glycosaminoglycans (GAGs) in healing fetal wound tissue. We used a sensitive assay for hexosamines to examine changes occurring in the development of normal sheep skin and of wound healing tissue in PVA sponges inserted subcutaneously at different stages of gestation. It was assumed that glucosamine was derived mainly from hyaluronan and galactosamine mainly from dermatan sulphate and chondroitin sulphate. Hexosamine-containing tissue infiltrating the sponges was deposited more rapidly in the first week than in the second week. Three days after wounding, approximately 70% of the total GAGs in wound tissue was hyaluronan. The proportion of hyaluronan then fell progressively and by the 14th day contributed 57% to the total GAGs. In uninjured skin the contribution of hyaluronan to the total GAGs fell progressively with increasing fetal maturity, the level being 70% at 75 days gestation, but only 35-40% in newborn or adult skin. At no stage of development was there a sudden change in GAG composition suggestive of a transition from regeneration to scar formation. It is concluded that hyaluronan may play an important role in the biochemical sequence leading to collagen fibrillogenesis and mature scar formation.

Animals↗
PubMed2005

O-GlcNAc modification of nucleocytoplasmic proteins and diabetes.

Nuclear and cytosolic proteins are glycosylated on serine or threonine residues by O-linked beta-N-acetylglucosamine (O-GlcNAc). O-GlcNAc modification is one of various posttranslational modifications and seems to be involved in the modulation of transcription and signal transduction. Accumulating data suggest a role for O-GlcNAc-modified proteins in diabetes, acting as a glucose sensor. It has been suggested that the hexosamine biosynthetic pathway is involved in the mechanism causing insulin resistance and diabetic complications. Excess glucose entering into the hexosamine biosynthetic pathway might cause elevated O-GlcNAc modification of various proteins. In this article, we review the current data regarding the relationship between O-GlcNAc modification and diabetes.

Acetylglucosamine↗
PubMed2006

Influence of sea buckthorn (Hippophae rhamnoides L.) flavone on dermal wound healing in rats.

The present investigation was undertaken to determine the efficacy of topical administration of flavone of sea buckthorn (Hippophae rhamnoides L.) on cutaneous wound healing in rats. Four full-thickness excision wounds were created on the back of rat and 1.0% w/v flavone prepared in propylene glycol was applied topically. Control animals received the vehicle alone in an identical manner. The healing of the wound was assessed by the rate of wound contraction, period of epithelialization, hydroxyproline, hexosamine, antioxidants estimation and histopathology of the granulation tissue. The sea buckthorn flavone promoted the wound healing activity as indicated by improved rate of wound contraction, decreased time taken for epithelialization (16.3 days versus 24.8 days in controls) and significant increase in hydroxyproline (26.0%) and hexosamine (30.0%) content. These findings were also confirmed by histopathological examinations. In addition, it was observed that sea buckthorn flavone possesses potent antioxidant properties as evidenced by significant increase in reduced glutathione (55.0%), vitamin C (70.0%) and catalase (20.0%) activities in wound granulation tissue. The flavone treatment also resulted in significant decrease in lipid peroxide levels (39.0%). The results suggest that the sea buckthorn flavone promotes wound healing activity.

Animals↗
PubMed1990

Direct carbohydrate analysis of glycoproteins electroblotted onto polyvinylidene difluoride membrane from sodium dodecyl sulfate-polyacrylamide gel.

A procedure for the carbohydrate analysis of glycoproteins electrotransferred to a polyvinylidene difluoride membrane is described. The glycoproteins (plant lectins, transferrin, and vitronectin) were first separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and then electroblotted onto a membrane. Each of the glycoprotein bands visualized by staining with Coomassie brilliant blue R-250 was excised from the membrane and subjected to direct hydrolysis either in 2.5 M trifluoroacetic acid at 100 degrees C for 6 h for neutral sugars and hexosamines, or in 0.05 M H2SO4 at 80 degrees C for 1 h for sialic acids. The hydrolysate obtained was analyzed for neutral sugars, hexosamines, and sialic acids independently by three different systems of high-performance liquid chromatography. The analytical values were reproducible with reasonable accuracy and agreed with those expected with recoveries of 57-66%. The method was successfully applied to a mannose-specific lectin of Sophora japonica bark, which is composed of four different subunits that aggregate sugar specifically. Because the four subunits could be separated by SDS-PAGE alone, the method proved useful for determining their carbohydrate compositions. Three of them were shown to contain carbohydrates typical of N-linked oligosaccharides of plant origin, which agreed well with the results of the binding assay carried out on a membrane using various horseradish peroxidase-labeled lectins.

Carbohydrates↗
PubMed1990

Saliva composition in asthmatic patients after treatment with two dose levels of a beta 2-adrenoceptor agonist.

Changes are known to occur in the salivary composition of asthmatic patients treated with beta 2-adrenoceptor agonists. To evaluate the precise contribution of the agonist to the impaired saliva secretion, 15 asthmatic patients, 15-23 yr old, were given two dose levels of agonist, either terbutaline or salbutamol. The lower dose, 0.15-3.0 mg/day, represented the therapeutic level used by the patients. During a wash-out period of one month, the asthma was treated with budesonide, a corticosteroid spray. Then a daily dose of 32 mg of terbutaline or salbutamol was given for one month. Samples of whole saliva, stimulated by chewing, and parotid saliva, stimulated by citric acid, were collected on three occasions: (1) at the end of the low-dose agonist treatment; (2) at the end of the wash-out period; and (3) at the end of the high-dose agonist treatment. During the high dosing the secretion rate of parotid saliva decreased and the concentrations of its total protein, amylase, hexosamine and the ratio of hexosamine/total protein were lowered. The output per minute of total protein, amylase, hexosamine, peroxidase, lysozyme, secretory IgA and potassium decreased. There were only small differences in secretion rates or saliva composition between samples collected at the end of the low-dose and at the end of the wash-out period. Thus, treatment with beta 2-adrenoceptor agonists impairs saliva secretion in asthmatics.

Adolescent↗
PubMed1976

Characterization of the hemoglobin of Biomphalaria glabrata as a glycoprotein.

1. The hemoglobin of Biomphalaria glabrata is a glycoprotein which contains 3% sugars. 2. The sugar moiety is composed of 2 mol of hexose and one mol of hexosamine per mol of monomer. 3. The hexosamine in the molecule is glucosamine. 4. Mannose, galactose and fucose are present in the molecule in a ratio of 2:1:1. 5. No sialic and uronic acids were detected in this hemoglobin.

Animals↗
PubMed1975

Enzymatic study of GM-1 gangliosidosis.

Two types of GM-1 gangliosidosis were studied biochemically. Type 1 liver accumulated non-lipid hexosamine in addition to GM-1 ganglioside, but there was no increase of hexosamine and GM-1 in type 2 liver. The optimum pH of liver beta-galactosidase of type 1 and type 2 was 5--6 while that of the normal control was 4.5. Type 1 brain beta-galactosidase showed a slightly acidic optimum pH, i.e. 4.0 in comparison with that of the normal control. The optimum pH of type 2 brain beta-galactosidase was 5.5, like the liver enzyme. The thermostability of liver beta-galactosidase was the same in type 1 and type 2, while that of brain was different. Beta-galactosidase of type 1 and type 2 liver is more stable at 42 degrees C than the normal control, but a different thermostability was observed in type 1 and type 2 brain. Liver beta-galactosidase of type 1 showed one peak each at acid and neutral pH, and type 2 liver had only one peak at neutral pH.

Autopsy↗
PubMed1977

Stimulation by prostaglandin F2alpha of acidic glycosaminoglycan production in cultured fibroblasts.

The effect of PGF2alpha on the synthesis of hexosamine-containing substances (acidic glycosaminoglycans and glycoproteins) was studied in cultured fibroblasts derived from a rat carrageenin granuloma. Treatment with PGF2alpha ranging from 0.01 mug/ml to 20 mug/ml resulted in a significant increase of the production of these macromolecules by the cells. The stimulatory effect was found significant even at the low concentration of 10 ng/ml, and could be seen as early as 3h after exposure to PGF2alpha. The hexosamine-containing substances increased by PGF2alpha revealed that 80% of the increase was due to acidic glycosaminoglycans and the rest was due to glycoproteins.

Animals↗
PubMed1982

Comparative biochemical studies of the callus matrix in immobilized and non-immobilized fractures.

Fracture healing in both non-immobilized and immobilized rat fracture callus, though different radiographically and histologically; is characterized by similar biochemical changes in the ground substance. Although the callus formed in the immobilized model is appreciably smaller than that formed when the fracture is not immobilized, the chemical composition of the organic matrix of the existing callus undergoes similar modifications regardless of fixation and histological response. Previous studies of endochondral fracture repair have demonstrated an elevation in fracture callus hexosamine content during the early stages of healing of the non-immobilized fracture. This corresponded histologically to a predominance of cartilaginous tissue in the callus matrix. In the present study, the biochemistry, histology, and roentgenographic features of stabilized and non-stabilized rat fractures are compared. Similar elevations in hexosamine are noted at two weeks in both models. These elevations are attributed to changes in proteoglycan rather than glycoprotein concentration of the tissue.

Animals↗
PubMed1995

The chemical modification of glycosaminoglycan structure by oxygen-derived species in vitro.

The effect of reactive oxygen species (ROS) on the chemical structure of glycosaminoglycans (GAG) was studied in order to consider their role in connective tissue damage during an inflammatory disease state such as periodontal disease. GAG were exposed to a radical generating system for 1 h and analysed by gel filtration for fragmentation and chemically with respect to uronic acid, hexosamine and sulfate content. Non-sulfated GAG, hyaluronan and chondroitin, were most susceptible to depolymerisation and chemical modification of uronic acid and hexosamine residues by ROS. Depolymerisation and chemical modification of sulfated GAG, chondroitin 4-sulfate, dermatan sulfate and heparan sulfate was significantly less than for non-sulfated GAG. The highly sulfated GAG heparin showed minimal depolymerisation by ROS, but uronic acid residues were readily modified. Analysis of the ROS-exposed residues suggests that uronic acid is capable of degrading to a 3-carbon aldehyde, malondialdehyde. Chondroitin sulfate exposed to ROS resulted in marginal desulfation. The results suggest that the presence of sulfate on the GAG chain may protect the molecule against ROS attack. However, chemical modification of GAG may affect proteoglycan function and be of importance in considering connective tissue destruction in a variety of pathological situations, including periodontal disease.

Chondroitin Sulfates↗
PubMed2006

The dual face of endogenous alpha-aminoketones: pro-oxidizing metabolic weapons.

Amino metabolites with potential prooxidant properties, particularly alpha-aminocarbonyls, are the focus of this review. Among them we emphasize 5-aminolevulinic acid (a heme precursor formed from succinyl-CoA and glycine), aminoacetone (a threonine and glycine metabolite), and hexosamines and hexosimines, formed by Schiff condensation of hexoses with basic amino acid residues of proteins. All these metabolites were shown, in vitro, to undergo enolization and subsequent aerobic oxidation, yielding oxyradicals and highly cyto- and genotoxic alpha-oxoaldehydes. Their metabolic roles in health and disease are examined here and compared in humans and experimental animals, including rats, quail, and octopus. In the past two decades, we have concentrated on two endogenous alpha-aminoketones: (i) 5-aminolevulinic acid (ALA), accumulated in acquired (e.g., lead poisoning) and inborn (e.g., intermittent acute porphyria) porphyric disorders, and (ii) aminoacetone (AA), putatively overproduced in diabetes mellitus and cri-du-chat syndrome. ALA and AA have been implicated as contributing sources of oxyradicals and oxidative stress in these diseases. The end product of ALA oxidation, 4,5-dioxovaleric acid (DOVA), is able to alkylate DNA guanine moieties, promote protein cross-linking, and damage GABAergic receptors of rat brain synaptosome preparations. In turn, methylglyoxal (MG), the end product of AA oxidation, is also highly cytotoxic and able to release iron from ferritin and copper from ceruloplasmin, and to aggregate proteins. This review covers chemical and biochemical aspects of these alpha-aminoketones and their putative roles in the oxidative stress associated with porphyrias, tyrosinosis, diabetes, and cri-du-chat. In addition, we comment briefly on a side prooxidant behaviour of hexosamines, that are known to constitute building blocks of several glycoproteins and to be involved in Schiff base-mediated enzymatic reactions.

Acetone↗
PubMed1975

[Preparative electrophoresis of peptidic glycosaminoglycans. Application to the fractionation of peptidic glycosaminoglycans of arterial wall (author's transl)].

A new procedure for the fractionation of glycosaminoglycans by electrophoresis on Pevikon has been described. Mixtures of glycosaminoglycans were fractionated by preparative electrophoresis on Pevikon in pyridine formate or glycine-HCl buffers. By this procedure, 200 mg of a mixture of hyaluronic acid, heparan sulphate, dermatan sulphate and chondroitin sulphate isolated from arterial wall could be successfully separated without loss of material. The purified fractions were analysed by enzymatic and chemical procedures. The molar ratios of uronic acid to hexosamine and of sulphate to hexosamine and the amino acid content of each glycosaminoglycan have been determined. The peptidic content (less than 1%) is represented by five amino acids, viz. serine, glycine, alanine, aspartic acid, and glutamic acid.

Amino Acids↗
PubMed1991

Experimental haemarthrosis in rhesus monkeys: morphometric, biochemical and metabolic analyses.

The effects of a single episode of massive haemarthrosis in rhesus monkeys were studied. Autologous whole blood was injected into a femorotibial joint of 16 anaesthetized monkeys, equally divided into four groups and killed 7 days, 2, 3 and 6 months post-injection (PI). Synovial membrane and femoral articular cartilage were analysed morphometrically and articular cartilage was further analysed biochemically and metabolically. At 7 days PI, morphometric evaluation revealed a significant increase (P less than 0.05) in synovial membrane cellularity and synovial intimal thickness of injected joints versus control joints. This change was no longer evident 2 months PI. There was also an overall (n = 16) significant increase (P less than 0.05) in femoral articular cartilage cellularity in injected joints. The average chondrocyte lacuna area of injected joints was not statistically different from the control joints. Biochemical analyses of femoral articular cartilage revealed a significant decrease in hexosamine concentration (P less than 0.05) of injected joints. There was no significant difference between the injected and control joints in hydroxyproline or total protein concentration. Metabolic analyses revealed a significant increase (P less than 0.05) in cartilage collagenous protein production by injected joints compared with control joints. There were no significant differences in cartilage or secreted total protein production between injected and control joints. There were also no significant differences in cartilage or secreted proteoglycan production between joints. Morphometric evaluation of articular tissues following massive haemarthrosis has quantified a temporary hyperplastic reaction. A significant decrease in cartilage hexosamine concentration in haemarthrotic joints suggests this is a crucial biochemical event in the pathogenesis of blood-induced cartilage destruction.

Animals↗