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PubMed1983

Impairment of human brain development: glycoconjugate and lipid changes in congenital athyroidism.

The brain glycoconjugates, glycosidases and lipids have been studied in a case of human congenital athyroidism never treated with hormonal replacement. Increase of membrane-bound mucopolysaccharides has been found in the grey matter. Total lipids in the white matter, and phospholipids, and total glycolipids and cholesterol in both white and grey matter were reduced. Sialic acid (NeuNAc) and hexosamines in the cytosol grey matter were significantly raised, while they were reduced in the membrane-bound grey fraction. These biochemical findings confirm impairment of the myelination process in human hypothyroidism as is well established in experimental hypothyroidism. The significant changes in the carbohydrate moieties of the brain glycoproteins focus attention on complex alterations of structure and function of the cell plasma membranes.

Adolescent↗
PubMed1980

Hyaluronic acid--an indicator of pulmonary injury?

Hyaluronic acid was the only glysosaminoglycan detected in the pulmonary secretions of healthy adult rats exposed to inhalation to methylene chloride, but not of control animals. The compound migrated as a single spot with the mobility of standard hyaluronic acid on cellulose acetate electrophoresis and disappeared after digestion with testicular hyaluronidase. Its identification was confirmed by finding hexuronate/hexosamine in a molar ratio of approx. 1. Glucosamine represented over 97% of the total hexosamine, the remaining 3% being galactosamine. No hexose or sulfate could be detected. Sodium dodecyl sulfate--polyacrylamide gel electrophoresis showed no protein associated with this glycosaminoglycan. It appears that the secretion of hyaluronic acid into the airways may be the result of pulmonary inflammation induced by the toxic effects of methylene chloride.

Animals↗
PubMed1995

Metal induced changes in the erythrocyte membrane of rats.

Lead, zinc and copper were administered i.p singly or in combination as acetate salts to rats for 14 consecutive days. It was observed that lead induced drastic changes, copper induced moderate changes but zinc did not cause any significant change in the cholesterol and phospholipid content, hexose, hexosamine and sialic acid levels and activities of the erythrocyte membrane enzymes--acetylcholinesterase (AChE), NADH dehydrogenase and Na(+)-K+ ATPase. In the combined metal treatment the presence of zinc considerably reduced the changes induced by lead and copper.

Acetylcholinesterase↗
PubMed1994

Alteration of femoral structure in later life by chronically feeding caffeine during rapid growing period in newborn female rats.

The effects of caffeine intake in early life on bone structure later in life were studied in rats. At day 9 of gestation, dams were divided into 2 groups. Group 1 (control) received a 20% protein diet; group 2 received the 20% protein diet supplemented with caffeine (2 mg/100 g body weight). After birth pups were continuously fed their respective diets until day 93, when the diet of group 2 was replaced with a noncaffeine 20% protein diet. On day 388 animals from both groups were weighed, killed, and femora and mandibles were removed. Calcium, phosphorus, magnesium, zinc, hydroxyproline, and hexosamine concentrations were measured. Radiographs of some femora were taken and paraffin cross sections were made at the midshaft of others. Femora in the caffeine group were wider, periosteal bone area/total bone area was greater, the cross sectional area of femoral bone was smaller, and there were fewer osteocytes/bone area than in controls. Calcium, phosphorus, zinc, and hydroxyproline concentrations in the caffeine group were less in both bones of the caffeine group. These results indicate that if animals are exposed to caffeine during the rapidly growing period, changes occur in femoral bone which are similar to those that occur with aging.

Animals↗
PubMedDate not supplied

Effect of banana powder (Musa sapientum var. paradisiaca) on gastric mucosal shedding.

Banana pulp powder (Musa sapientum Linn. var. paradisiaca) was studied for its effects on gastric mucosal resistance. Banana-treated (0.5 g/kg orally, twice daily for 3 days) rats of either sex showed: (i) a significant increase in the [3H]thymidine incorporation into mucosal cell DNA; (ii) a significant increase in the total carbohydrate (sum of total hexoses, hexosamine, fucose and sialic acid) content of gastric mucosa; (iii) a significant decrease in gastric juice DNA and protein; (iv) a significant increase in the total carbohydrates and carbohydrate/protein ratio of gastric juice. Aspirin treatment to rats caused similar effects as banana on the [3H]thymidine incorporation into mucosal cell DNA but showed opposite effects on the other parameters. These results suggest that banana treatment increased and aspirin decreased the gastric mucosal resistance as evidenced by a respective decrease and increase in gastric juice DNA, the latter serving as an index of the rate of mucosal shedding. Increased cellular mucus may be the factor for increased mucosal resistance. The results of the present study tend to confirm that plantain banana powder strengthens mucosal resistance and promotes the healing of ulcers.

Animals↗
PubMed1994

Antiulcerogenicity of the flavonoid fraction from Bidens aurea: comparison with ranitidine and omeprazole.

Effects of the flavonoid fraction of Bidens aurea (Aiton) Sherff on gastric ulceration induced by restraint and cold were studied in rats. Mucosal damage was evaluated histomorphometrically and the results were compared with those of omeprazole and ranitidine. The effects of these agents on the quantity and quality of the gastric mucus were also determined histologically and biochemically. Oral treatment with the ether fraction of the flavonoid extract gave the highest level of gastric protection. Mucus content was increased and accompanied by a proportional increase in proteins and hexosamines. There was also a marked increase of the periodic acid-Shiff (PAS) area (neutral glycoprotein) and the alcian blue (AB) area (sulphated glycoprotein). The groups which received ranitidine and omeprazole did not overcome the inhibition of the mucus secretion induced in this experimental model.

Acute Disease↗
PubMed1986

Carbohydrate composition of sarcolemma of rat myocardium.

The carbohydrate composition of SL prepared from rat ventricular muscle was examined and compared with those of Mw and FSR prepared from the same species. The total carbohydrate content of SL was 308.58 micrograms/mg of protein, which was greater than that of Mw (74.49 micrograms/mg of protein) and FSR (76.50 micrograms/mg of protein). The carbohydrate of SL was composed of hexose (35.0%), hexuronic acid (7.3%), sialic acid (6.1%), methyl pentose (7.4%), and hexosamine (44.2%). The peculiar PAS-positive glycoproteins of SL were observed as five bands on polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate and the molecular weight of the main band of these was 85.4 kDa. Thus, each of the cell fractions obviously shows a distinct carbohydrate composition and the results obtained in the present study may suggest that the presence of the PAS-positive glycoprotein (85.4 kDa) can be used for routine monitoring of the purity of the SL fraction.

Animals↗
PubMed1990

Glycopeptide in sputum from allergic asthma patients.

The glycopeptide and glycosaminoglycan content of sputa from allergic asthma, bronchiectasis, and common cold patients was assayed. The glycopeptide content was higher in sputum from allergic asthma patients than that in bronchiectasis and common cold patients, while no significant difference in the glycosaminoglycan content was detected among these materials. Fractionation of the glycopeptide by DEAE-cellulose column chromatography yielded four glycopeptide fractions at concentrations of 0.05 to 0.3 M NaCl from the allergic asthma samples, whereas it yielded three fractions at concentrations of 0.05 to 0.2 M NaCl from the bronchiectasis and common cold samples. They were characterized by increases in sialic acid and sulfate as the molarity of NaCl increased. Hexose was the main component and hexosamine was the next in each fraction from all materials. The increase in sputum glycopeptide in the allergic asthma samples was due to a large increase in sialic acid- and sulfate-rich glycopeptide.

Adult↗
PubMed1993

Glycolipids isolated from cultured rat hepatocytes: analysis of their role in insulin signal transduction.

The precise mechanism by which insulin elicits its effects remains to be fully determined. A glycophospholipid, isolated from H35 cells, has been proposed as a possible precursor for an insulin-generated second messenger that mediates the intracellular effects of insulin. This glycolipid contains a hexosamine moiety, inositol, galactose and palmitate. We have isolated a glycolipid from cultured rat hepatocytes that exhibits chromatographic and radiolabelling characteristics similar to this proposed precursor. The glycolipid can be radiolabelled with glucosamine, galactosamine, galactose and palmitate, but not myristate or myoinositol. Incorporation of radiolabel into this glycolipid was insensitive to the presence of either insulin (10(-7) M) or phosphatidylinositol-specific phospholipase C (PI-PLC) in the culture medium. The cultured hepatocytes used exhibited normal insulin responses with respect to glycogen turnover and gene expression. Treatment of partially purified glycolipid with either PI-PLC or nitrous acid did not result in the generation of an aqueous soluble phosphooligosaccharide indicating that the glycolipid was not cleaved by either agent. This is in contrast to the reported cleavage of the glycolipids found in H35 hepatoma and lymphocytes. These results question the role of the putative phosphooligosaccharide mediator in the intracellular transduction system activated by insulin.

Albumins↗
PubMed1995

Low-density lipoprotein binding affinity of arterial chondroitin sulfate proteoglycan variants modulates cholesteryl ester accumulation in macrophages.

Proteoglycans are considered to facilitate lipid accumulation in the arterial wall, as part of the injury and repair process in atherogenesis. The present study determined (1) characteristics of arterial tissue chondroitin sulfate proteoglycan (CS-PG) monomers of versican type that vary in binding affinity to low-density lipoproteins (LDL), and (2) the ability of these variants to modulate LDL metabolism by macrophages. A large CS-PG devoid of dermatan sulfate (DS) was isolated and purified from bovine aorta intima-media under dissociative conditions. The proteoglycan was further subfractionated by LDL affinity chromatography into CS-PGI and CS-PGII variants, the former eluting at 0.1 M NaCl and the latter at 1.0 M NaCl. The core protein of both variants had a similar molecular mass (1.7 x 10(5). However, CS-PGII contained more glycosaminoglycan (GAG) chains (30 vs. 25) with higher average molecular mass (4.2 x 10(4) vs. 3.8 x 10(4)) than CS-PGI. Furthermore, CS-PGII contained a relatively higher proportion of CS6-sulfate to CS4-sulfate (65: 35 vs. 52: 48). Sulfate-to-hexosamine molar ratio of GAG measured approximately 1 in both variants. In terms of metabolism by macrophages, when compared to complex of LDL and CS-PGI, complex of LDL and CS-PGII produced consistent increase in degradation (10.3-fold vs. 8.4-fold over native LDL) and cell association (16.3-fold vs. 10.2-fold over native LDL) of the ligand, and stimulation of cholesteryl ester synthesis (8.4-fold vs. 6.4-fold over native LDL). CS-PGII was as potent as native CS/DS-PG aggregate, which is a complex made of proteoglycan monomers, hyaluronate, and link protein(s), in stimulating the above activities in macrophages. Thus, variations in LDL-binding affinity of CS-PG can potentially modulate the lipid accumulation in atherogenesis.

Amino Acids↗
PubMed1996

Glycoprotein metabolism in dimethylnitrosamine induced hepatic fibrosis in rats.

Glycoproteins play a major role in the pathogenesis of hepatic fibrosis by accumulating in the sinusoids and the space of Disse. In order to obtain more information about the altered metabolism of glycoproteins during the development of human hepatic fibrosis, the carbohydrate moieties of the glycoproteins were monitored in experimentally induced hepatic fibrosis. The liver injury was induced by injecting dimethylnitrosamine intraperitoneally in male albino rats. The injections were given on the first 3 consecutive days of each week over a period of 21 days. Glycoprotein moieties such as total hexose, hexosamine, fucose and sialic acid were estimated in liver, serum and urine samples on days 7, 14 and 21 of the experiment. The results indicated a significant decrease in total hexose and an increase in fucose levels in the liver tissue during dimethylnitrosamine administration. While protein bound hexose in the serum showed a significant decrease, sialic acid levels were notably increased. The other glycoprotein moieties both in liver and serum also showed an increase in the later periods of study, especially on day 21. All glycoprotein moieties exhibited a significant increase in the rate of urinary excretion on the 14th and 21st days, indicating an increased rate of metabolic degradation in the acute phase of hepatic fibrosis. The results suggest that glycoproteins undergo changes in both synthesis and the degradation during hepatic fibrosis. The relative alterations in these processes will play a vital role in determining the progression of hepatic fibrosis.

Animals↗
PubMed2005

GC/MS identification and quantification of constituents of bacterial lipids and glycoconjugates obtained after methanolysis as heptafluorobutyrate derivatives.

In previous articles [Anal. Biochem. 284 (2000) 201; J. Lipid Res. 43 (2002) 794], we reported that the GC/MS identification and quantification of nearly all constituents of glycolipids could be obtained on the same sample in a single GC/MS analysis as heptafluorobutyrate derivatives of the products liberated using acid-catalyzed methanolysis. The same type of data could be obtained on glycoproteins and proteoglycans [Biochemistry 42 (2003) 8342]. These experiments were performed on material from higher organisms, and there was no evidence that bacteria-specific constituents could also be identified and quantified. The current article reports that the GC/MS analysis of compounds liberated by acid-catalyzed methanolysis as heptafluorobutyrate derivatives allows the simultaneous qualitative and quantitative determinations of pentoses, deoxyhexoses, hexoses, hexosamines, uronic acids, Kdo, Mur, heptose, Kdn, and neuraminic acid as well as of most fatty acids (including hydroxylated fatty acids). This approach provides a way of obtaining fingerprints of bacterial constituents and quantification of the overall effect of gene inactivation or of culture conditions.

Bacteria↗
PubMed2006

The effect of glucosamine concentration on the development and sex ratio of bovine embryos.

Glucosamine is a component of hyaluronic acid and an alternative substrate to glucose for the extracellular matrix synthesis of COCs. Its addition to an IVM medium reduces the glucose consumption of bovine COCs. Glucosamine is also metabolized to UDP-N-acetyl glucosamine (UDP-GlcNAc) via the hexosamine biosynthesis pathway and is utilized for O-linked glycosylation by the X-linked enzyme, O-linked GlcNAc transferase (OGT). Moreover, the inactivation of the second X chromosome in female embryos is influential in producing the sex ratio bias observed in vitro when embryos are cultured in the presence of glucose above 2.5mM. Accordingly, the aim of this study is to examine whether the presence of glucosamine during maturation or embryo culture causes a sex ratio bias in bovine blastocysts. Glucosamine was added to the medium in three different embryo developmental periods: in vitro maturation, the one-cell to eight-cell stage (before the maternal-zygotic transition, MZT), and the eight-cell to blastocyst stage (after MZT). When glucosamine was added during in vitro maturation, the developmental competence of oocytes was severely compromised. However, the sex ratio of embryos was not influenced. When glucosamine was added to embryo culture medium during development from one-cell to eight-cell stage (before MZT), it affected neither the development nor the sex ratio of bovine embryos. Finally, when glucosamine was added after MZT, the development rate of embryos was severely decreased, and the sex ratio was skewed toward males. Moreover, an inhibitor of OGT, benzyl-2-acetamido-2-deoxy-alpha-D-galactopyranoside (BADGP), negated the effect of glucosamine on the sex ratio when it was added to embryo culture medium from the eight-cell to blastocyst stage (after MZT). These results suggest that, like glucose, the supplementation of glucosamine into the medium skewed the sex ratio to males and that OGT, an X-linked enzyme, was involved in this phenomenon. Moreover, this effect of glucosamine was limited only to when it was present in the embryo culture medium after MZT.

Animals↗
PubMed2003

Sulfation patterns in heparin and heparan sulfate: effects on the proliferation of bovine pulmonary artery smooth muscle cells.

Heparin's (HP's) antiproliferative effect on smooth muscle cells is potentially important in defining new approaches to treat pulmonary hypertension. The commercially available HP and heparan sulfate (HS) are structurally heterogenous polymers. In order to examine which sulfonate groups are required for endogenous antiproliferative activity, we prepared the following six chemically modified porcine mucosal HP and HS, which fell into three groups. One group consisted of fully O-sulfonated-N-acetylated, the second group consisted of de-N-sulfonated and re-N-acetylated, and the third group consisted of 6-O-desulfonated HP and HS derivatives. These six preparations were assayed for their antiproliferative potency on bovine pulmonary artery smooth muscle cells. The results of this assay show that (a) over-O-sulfonation of both HP and HS increases antiproliferative activity, (b) substitution of hexosamine with N-acetyl diminishes antiproliferative activity in both HP and HS, and (c) 6-O-desulfonation of HP and HS diminishes antiproliferative potency. Surprisingly, the type of uronic acid residue present at a given level of sulfation is unimportant for antiproliferative potency. In conclusion, only the level of O- and N-sulfo group substitution correlates well with HP and HS antiproliferative activity.

Animals↗
PubMed2004

The effect of finger millet feeding on the early responses during the process of wound healing in diabetic rats.

In the present study, the role of finger millet feeding on skin antioxidant status, nerve growth factor (NGF) production and wound healing parameters in healing impaired early diabetic rats is reported. Hyperglycemic rats received food containing 50 g/100 g finger millet (FM). Non-diabetic controls and diabetic controls received balanced nutritive diet. Full-thickness excision skin wounds were made after 2 weeks prior feeding of finger millet diet. The rate of wound contraction, and the levels of collagen, hexosamine and uronic acid in the granulation tissue were determined. The skin antioxidant status and lipid peroxide concentration were also monitored during the study. In hyperglycemic rats fed with finger millet diet, the healing process was hastened with an increased rate of wound contraction. Skin levels of glutathione (GSH), ascorbic acid and alpha-tocopherol in alloxan-induced diabetic rat were lower as compared to non-diabetics. Altered activities of superoxide dismutase (SOD) and catalase (CAT) were also recorded in diabetics. Interestingly, thiobarbituric acid reactive substances (TBARS) were elevated in the wound tissues of all the groups, when compared to normal (unwounded) skin tissues. However, in diabetic rats the TBARS levels of both normal and wounded skin tissues were significantly elevated (P < 0.001) when compared with control (non-diabetic) and diabetics fed with FM. Impaired production of NGF, determined by ELISA, in diabetic rats was improved upon FM feeding and further confirmed by immunocytochemical observations reflects the increased expression of NGF in hyperglycemic rats supplemented with FM-enriched diet. Histological and electron microscopical evaluations revealed the epithelialization, increased synthesis of collagen, activation of fibroblasts and mast cells in FM-fed animals. Thus, increased levels of oxidative stress markers accompanied by decreased levels of antioxidants play a vital role in delaying wound healing in diabetic rats. However, FM feeding to the diabetic animals, for 4 weeks, controlled the glucose levels and improved the antioxidant status, which hastened the dermal wound healing process.

Animals↗
PubMed2006

Ca2+-transport in sea urchin unfertilized eggs: regulation by endogenous sulfated polysaccharides and K+.

Previous data from our laboratory showed that the reticulum of the sea cucumber smooth muscle body wall retains both a sarco/endoplasmic reticulum Ca(2+)-ATPase (SERCA) and a sulfated polysaccharide. In this invertebrate, the transport of Ca(2+) by the SERCA is naturally inhibited by these endogenous sulfated polysaccharides. The inhibition is reverted by K(+) leading to an enhancement of the Ca(2+) transport rate. We now show that vesicles derived from the endoplasmic reticulum of unfertilized eggs from the sea urchin Arbacia lixula retain a SERCA that is able to transport Ca(2+) at the expense of ATP hydrolysis. As described for the sea cucumber SERCA isoform, the enzyme from the sea urchin is activated by K(+) but not by Li(+) and is inhibited by thapsigargin, a specific inhibitor of SERCA. A new sulfated polysaccharide was identified in the sea urchin eggs reticulum composed mainly by galactose, glucose, hexosamine and manose. After extraction and purification, this sulfated polysaccharide was able to inhibit the mammal SERCA isoform found in rabbit skeletal muscle and the inhibition is reversed by K(+). These data suggest that the regulation of the SERCA pump by K(+) and sulfated polysaccharides is not restricted to few marine invertebrates but is widespread.

Animals↗
PubMed2004

Selective decrease of membrane-associated PKC-alpha and PKC-epsilon in response to elevated intracellular O-GlcNAc levels in transformed human glial cells.

Increased flux through the hexosamine biosynthetic pathway (HBP) has been shown to affect the activity and translocation of certain protein kinase C (PKC) isoforms. It has been suggested that this effect is due to increases in the beta-O-linked N-acetylglucosamine (O-GlcNAc) modification. Herein, we demonstrate the effect of increasing the O-GlcNAc modification on the translocation of select PKC isozymes in a human astroglial cell line. Treating cells with either 8 mM d-glucosamine (GlcN), 5 mM streptozotocin (STZ), or 80 muM O-(2-acetamido-2-deoxy-d-glucopyranosylidene)amino-N-phenylcarbamate (PUGNAc) produced a significant increase in the O-GlcNAc modification on both cytosolic and membrane proteins; however, both the level and rate of O-GlcNAc increase varied with the compound. GlcN treatment resulted in a rapid, transient translocation of PKC-betaII that was maximal after 3 h (73+/-8%) and also produced a 48+/-15% decrease in membrane-associated PKC-epsilon after 9 h of treatment. Similar to GlcN treatment, STZ and PUGNAc treatment also resulted in decreased levels of PKC-epsilon in the membrane fraction. Significant decreases were seen as early as 5 h and, by 9 h of treatment, had decreased by 87+/-6% with STZ and 73+/-7% with PUGNAc. Unlike GlcN, both STZ and PUGNAc produced a decrease in PKC-alpha membrane levels by 9 h posttreatment (78+/-10% with STZ and 66+/-8% with PUGNAc) while neither compound produced any changes in PKC-betaII translocation. In addition, none of the three compounds affected membrane levels of PKC-iota. Altogether, these results demonstrate a novel link between increased levels of the O-GlcNAc modification and the regulation of specific PKC isoforms.

Acetylglucosamine↗
PubMed2003

Stimulation of PAI-1 and adipokines by glucose in human adipose tissue in vitro.

Adipokines such as Plasminogen activator inhibitor-1 (PAI-1), interleukin (IL)-8, and tumor necrosis factor (TNF)-alpha are elevated in patients with obesity, insulin resistance, and type 2 diabetes. In the present study, we investigated whether glucose affected the production of these adipokines in human adipose tissue in vitro. Glucose (up to 35mM) increased secretion of PAI-1 (p<0.01) and IL-8 (p<0.01), but not TNF-alpha, in a dose- and time-dependent manner. Half-maximal stimulatory concentration of glucose was about 1mM. Glucosamine (5mM) decreased production of PAI-1 (p<0.05) and IL-8 (p<0.05), indicating that the hexosamine biosynthesis pathway is not involved in the glucose-induced increment in adipokine secretion. The present data demonstrate that glucose increases PAI-1 and IL-8 secretion. However, glucose concentrations above 5mM had no additional effects on adipokine secretion, suggesting that mechanisms other than diabetes/insulin resistance-related hyperglycemia may be involved in the observed elevation of these adipokines.

Adipose Tissue↗