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PubMed1975

Cell wall composition and incorporation of radio-labelled compounds by Veillonella alcalescens.

The cell wall of Veillonella alcalescens was shown to have a typically Gram-negative appearance and composition. The wall contains 24% lipid, 0.8% phosphorus, and 6.8% hexosamine. It is estimated to contain about 5% murein, unlike the 24% reported by other for Veillonella parvula. The amounts of 19 amino acids, including diaminopimelic acid, were determined. Though Veillonella sp. cannot metabolize sugars for energy, V. alcalescens incorporates ribose and fructose by separate, specific mechanisms and uses most of the incorporated sugar in nucleic acid synthesis. Large excesses of either sugar in the medium do not repress gluconeogenesis from the pyruvate level. We have been unable to detect phosphoglyceromutase (EC 2.7.5.3) by several assay methods but have no indication of a gluconeogenic pathway other than reverse glycolysis.

Amino Acids↗
PubMed1977

Breakdown of mucin and plant polysaccharides in the human colon.

To obtain an estimate of the extent to which complex carbohydrates are degraded by bacteria in the human colon, aqueous extracts of colon contents from four human subjects were separated into high and low molecular weight fractions by chromatography on a Sephadex G-100 column. The composition of these fractions was compared with the composition of similar fractions from ileal contents, i.e., from material entering the colon. In all four subjects, high molecular weight carbohydrate concentrations were lower in the colon than in the ileum, indicating that breakdown of complex carbohydrate occurs in the colon. The high molecular weight carbohydrate fraction contained sugars characteristic of plant polysaccharides (arabinose, xylose, mannose, rhamnose) as well as sugars characteristic of mucin (fucose, hexosamines, sialic acids). Concentrations of most of these sugars were uniformly lower in the colon than in the ileum. Since high molecular weight protein concentrations were lower in the colon than in the ileum of two of the four subjects tested, some degradation of protein may also occur in the colon.

Amino Acids↗
PubMed2006

Glucosamine protects neonatal cardiomyocytes from ischemia-reperfusion injury via increased protein-associated O-GlcNAc.

Increased levels of protein O-linked N-acetylglucosamine (O-GlcNAc) have been shown to increase cell survival following stress. Therefore, the goal of this study was to determine whether in isolated neonatal rat ventricular myocytes (NRVMs) an increase in protein O-GlcNAcylation resulted in improved survival and viability following ischemia-reperfusion (I/R). NRVMs were exposed to 4 h of ischemia and 16 h of reperfusion, and cell viability, necrosis, apoptosis, and O-GlcNAc levels were assessed. Treatment of cells with glucosamine, hyperglycemia, or O-(2-acetamido-2-deoxy-D-glucopyranosylidene)-amino-N-phenylcarbamate(PUGNAc), an inhibitor of O-GlcNAcase, significantly increased O-GlcNAc levels and improved cell viability, as well as reducing both necrosis and apoptosis compared with untreated cells following I/R. Alloxan, an inhibitor of O-GlcNAc transferase, markedly reduced O-GlcNAc levels and exacerbated I/R injury. The improved survival with hyperglycemia was attenuated by azaserine, which inhibits glucose metabolism via the hexosamine biosynthesis pathway. Reperfusion in the absence of glucose reduced O-GlcNAc levels on reperfusion compared with normal glucose conditions and decreased cell viability. O-GlcNAc levels significantly correlated with cell viability during reperfusion. The effects of glucosamine and PUGNAc on cellular viability were associated with reduced calcineurin activation as measured by translocation of nuclear factor of activated T cells, suggesting that increased O-GlcNAc levels may attenuate I/R induced increase in cytosolic Ca(2+). These data support the concept that activation of metabolic pathways leading to an increase in O-GlcNAc levels is an endogenous stress-activated response and that augmentation of this response improves cell survival. Thus strategies designed to activate these pathways may represent novel interventions for inducing cardioprotection.

Acetylglucosamine↗
PubMed2005

Glucosamine inhibits angiotensin II-induced cytoplasmic Ca2+ elevation in neonatal cardiomyocytes via protein-associated O-linked N-acetylglucosamine.

We previously reported that glucosamine and hyperglycemia attenuate the response of cardiomyocytes to inositol 1,4,5-trisphosphate-generating agonists such as ANG II. This appears to be related to an increase in flux through the hexosamine biosynthesis pathway (HBP) and decreased Ca2+ entry into the cells; however, a direct link between HBP and intracellular Ca2+ homeostasis has not been established. Therefore, using neonatal rat ventricular myocytes, we investigated the relationship between glucosamine treatment; the concentration of UDP-N-acetylglucosamine (UDP-GlcNAc), an end product of the HBP; and the level of protein O-linked N-acetylglucosamine (O-GlcNAc) on ANG II-mediated changes in intracellular free Ca2+ concentration ([Ca2+]i). We found that glucosamine blocked ANG II-induced [Ca2+]i increase and that this phenomenon was associated with a significant increase in UDP-GlcNAc and O-GlcNAc levels. O-(2-acetamido-2-deoxy-D-glucopyranosylidene)-amino-N-phenylcarbamate, an inhibitor of O-GlcNAcase that increased O-GlcNAc levels without changing UDP-GlcNAc concentrations, mimicked the effect of glucosamine on the ANG II-induced increase in [Ca2+]i. An inhibitor of O-GlcNAc-transferase, alloxan, prevented the glucosamine-induced increase in O-GlcNAc but not the increase in UDP-GlcNAc; however, alloxan abrogated the inhibition of the ANG II-induced increase in [Ca2+]i. These data support the notion that changes in O-GlcNAc levels mediated via increased HBP flux may be involved in the regulation of [Ca2+]i homeostasis in the heart.

Acetylglucosamine↗
PubMed1975

Changes in vascular ionic content and distribution across aortic coarctation in the dog.

Eight dogs were subjected to 80-90 percent coarctation of thoracic aorta, which produced a mean blood pressure gradient of 40 mmHg; six normal dogs were used as controls. Proximal aorta was compared with distal aorta, and carotid and femoral arteries removed after coarctation were compared against the contralateral vessels removed before coarctation. After 4 wk of coarctation, proximal aorta contained more total and intracellular Na (derived from 24Na fluxes and space measurements), more Mg, Cl, hydrolyzable SO4 equals to, and H2O than distal aorta. Hydrolyzable SO4 equals to was also higher in proximal than in distal noncoarcted aorta. Carotid arteries removed after coarctation had higher total and "noninulin" Na, higher Ca, and similar hydrolyzable SO4equals to and total hexosamine than the contralateral normal vessels. Aortic coarctation had no effect on ionic composition of femoral arteries. The data suggest that an increase in intravascular pressure has direct effects on vascular ionic composition. Although ionic changes may vary in different vessels, increased intracellular Na seems to be the most consistent finding.

Animals↗
PubMed1999

Lipoid proteinosis (Urbach-Wiethe disease).

The aim of this study has been to assess the clinical presentation and biochemical profile of lipoid proteinosis within a defined pedigree. Glycoprotein analysis was compared to normal values in an attempt to define a biochemical phenotype. Six affected family members were identified with variable degrees of disease expression. The most likely mode of inheritance is autosomal recessive due to consanguinity. Routine laboratory investigations were normal in all family members tested. The total content of mucopolysaccharides, sialic acid and hexosamine in biopsed tissue was significantly lower than normal. Our findings demonstrate that a defect in glycoprotein synthesis, possibly enzymatic, may be the cause of lipid proteinosis and its protean clinical manifestations.

Adult↗
PubMed1994

Antiulcer and gastroprotective effects of quercetin: a gross and histologic study.

This study was designed to determine the cytoprotective properties of quercetin and the involvement of endogenous prostaglandins in mucosal injury produced by absolute ethanol. Gastric glands were also analyzed histologically. Oral pretreatment with the highest dose of quercetin (200 mg/kg), 120 min before absolute ethanol, was most effective in necrosis prevention. Subcutaneous administration of indomethacin (10 mg/kg) to the animals treated with quercetin (200 mg/kg) partially inhibited gastric protection. All treated groups showed a marked increase in the amount of gastric mucus although this increase was less in animals pretreated with indomethacin. Total proteins and the hexosamine content decreased in the groups receiving indomethacin. The histomorphometric evaluation of the gastric damage confirmed a significant increase in mucus production accompanied by a parallel reduction of gastric lesions with the highest dose of quercetin tested.

Animals↗
PubMed1994

Antiulcer effect of naringin on gastric lesions induced by ethanol in rats.

This study was designed to determine the gastroprotective properties of naringin on and the involvement of endogenous prostaglandins in mucosal injury produced by absolute ethanol. Oral pretreatment with the highest dose of naringin (400 mg/kg), 60 min before absolute ethanol was the most effective antiulcer treatment. Subcutaneous administration of indomethacin (10 mg/kg) to the animals treated with naringin (400 mg/kg) partially inhibited gastric protection, but the prostaglandin E2 determination did not show any increase in prostanoid levels. The contents of gastric mucus and total proteins were not significantly modified. Naringin-treated rats showed a marked increase in hexosamine levels, but this increase was less in animals pretreated with indomethacin. These results show that naringin has a 'cytoprotective' effect against ethanol injury in the rat, but this property appears to be mediated by non-prostaglandin-dependent mechanisms.

Animals↗
PubMed1977

Variation of the glycosaminoglycans of the intervertebral disc with ageing. II. Non-chondrodystrophoid breed.

The variation with age and spinal level of the glycosaminoglycan distribution in the greyhound (a non-chondrodystrophoid breed) intervertebral disc has been assessed by means of histochemical and chemical methods. The principal glycosaminoglycans of the greyhound disc are the chondroitin sulphates. With ageing, there is evidence of a decline in these components and the replacement by keratosulphate. The discs of this breed contain high proportions of sialic acid and hexosamines well into old age which are thought to be associated with non-collagenous proteins (glycoproteins). The maintenance of glycosaminoglycans and glycoprotein levels in the disc nucleus pulposus into old age is possibly associated with the relatively low incidence of disc disorders in the non-chondrodystrophoid breeds.

Aging↗
PubMed1971

The glycosaminoglycans of normal and arthritic cartilage.

The cartilages from the hip joints of 13 normal and 15 osteoarthritic humans were analyzed for glycosaminoglycan content and distribution. The GAGs were separated by elution with CPC on a short cellulose column by the technique of Svejcar and Robertson after digestion of the tissue with pronase and papain. The eluates were identified by a variety of methods including determination of molar ratios, N-acetyl-hexosamine determinations after hyaluronidase treatment and thin-layer chromatography of unhydrolyzed and hydrolyzed GAGs. From the data obtained, it was demonstrated that cartilage from arthritic patients showed a significant increase in the concentration of chondroitin 4-sulfate and a significant decrease in keratan sulfate, with only slight changes in the total amount of GAG present. Calculations of the molar ratios showed variation in the sulfation with chondroitin 4-sulfate appearing in the "supersulfated" state in the arthritic cartilage. The data lead to speculation regarding the process of osteoarthritis, and it is concluded that the changes seen are more likely to represent an altered pattern of synthesis rather than selective degradation. Since the changes suggest a younger cartilage, a theory is advanced that the chondrocyte responds to the chronic stress of osteoarthritis by modulation to a chondroblastic phase.

Aged↗
PubMed2002

Identification of a biochemical link between energy intake and energy expenditure.

Obesity is the result of an imbalance between energy intake and energy expenditure. Using high-density DNA microarrays and Northern analyses, we demonstrated that the activation of a nutrient-sensing pathway, the hexosamine biosynthesis pathway (HBP), rapidly decreased the expression of a cluster of nuclear-encoded mitochondrial genes involved in skeletal muscle oxidative phosphorylation. Conversely, the expression of uncoupling protein-1 and of the same mitochondrial genes was increased in brown adipose tissue. Most important, these transcriptional changes were accompanied by a marked decrease in whole-body energy expenditure. Short-term overfeeding replicated this transcriptional pattern, suggesting that this adaptation to nutrient abundance occurs under physiological conditions. Thus, the activation of the HBP by nutrients represents a biochemical link between nutrient availability, mitochondrial proteins, and energy expenditure, and it is likely to play an important role in the regulation of energy balance.

Animals↗
PubMed1977

Study of the noncollagenous components of the periodontium.

Periodontal ligament and gingivae of bovine and porcine periodontium were analyzed for relative amounts of carbohydrates, collagen, and acid mucopolysaccharides. The sugar content was 3.6% and 3.4% of dry weight in bovine and porcine periodontal ligament, respectively. The values were lower in the gingivae being 2.34% and 2.30%, respectively. Approximately 50% of hexosamine in gingivae was present in acid mucopolysacchrides as compared to 36% in periodontal ligament. Relative to collagen there was a considerable amount of non-collagenous glycoproteins present in the periodontium as judged by carbohydrate content of the tissue.

Animals↗
PubMed1989

Purification of lingual amylase from serous glands of rat tongue and characterization of rat lingual amylase and lingual lipase.

Lingual amylase and lingual lipase, two digestive enzymes that are secreted from lingual serous glands (von Ebner's), were simultaneously purified from rat lingual serous glands with hydrophobic chromatography used as the final step. This method, previously developed for the purification of lingual lipase, includes homogenization of rat lingual serous glands, 100,000 g centrifugation, ammonium sulfate precipitation of proteins, and extraction of lipids with acetone at -20 degrees C, followed by hydrophobic chromatography on ethyl agarose or Agethane. Amylase was eluted after the elution of proteins that did not interact with the hydrophobic gel at pH 6.3. Lingual lipase was eluted with a solution containing micelles of taurodeoxycholate, monoolein, and oleic acid. Analysis of each of the purified enzymes by SDS-polyacrylamide gel electrophoresis revealed one band at Mr = 59,000 for amylase and one band at Mr = 51,000 for lingual lipase. Isoelectric focusing of amylase indicated a strong band at pI = 5.0 and two very faint bands at pI = 4.9 and 4.8, possibly isozymes or deamidated protein. Amino acid and hexosamine analyses were performed on the enzymes after electroelution from SDS-polyacrylamide gels. Both lingual lipase and lingual amylase had a high content of dicarboxylic (free and amide) amino acids. For lingual lipase and lingual amylase, the % molar ratios of aspartic acid/asparagine were 15.35 and 15.10, and the % molar ratios of glutamic acid/glutamine were 7.07 and 7.20, respectively. Lingual amylase was very similar to rat parotid, pancreatic, and mouse salivary amylases, except that it contained more proline (11.03% molar ratio).(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMedDate not supplied

Matrix assessment of the articular cartilage surface after chondroplasty with the holmium:YAG laser.

The goal of this study was to evaluate, histologically and biochemically, repair of the articular cartilage in a rabbit joint after the use of the holmium:yttrium-aluminum-garnet laser in a cartilage chondroplasty model. In 30 New Zealand White rabbits, chondroplasty was performed with the laser at an intensity of 0.8 J at a rate of 10 Hz. The animals were sacrificed 12 weeks after surgery. Histologically, the safranin O staining index of proteoglycan correlated well with the biochemical results, illustrating a decrease of proteoglycan in the repaired articular cartilage after laser articular cartilage chondroplasty. The damaged articular cartilage surface after the laser application was extensive. The damaged area observed was gradually distributed along the radius from the central point of the laser beam application. Biochemically, the amount of glycosaminoglycan in the repaired tissue (8 +/- 2 mg of hexosamine per gram of dry cartilage) was statistically less when compared with that in the sham-treated tissue (40 +/- 5 mg). The amount of sulfate incorporated into proteoglycans was 8 to 10 times less in the chondroplasty model compared with the control, suggesting that cell viability was greatly reduced in the treated tissues or expression of proteoglycans was greatly reduced. In the subchondral area, histologic evaluation showed the lack of osteocytes in lacunae of the bone tissue after use of laser energy. The architecture of the subchondral bone in the chondroplasty area was damaged, with damage also seen in the membranes of the blood vessels.

Aluminum Silicates↗
PubMed2004

The cellular fate of glucose and its relevance in type 2 diabetes.

Type 2 diabetes is a complex disorder with diminished insulin secretion and insulin action contributing to the hyperglycemia and wide range of metabolic defects that underlie the disease. The contribution of glucose metabolic pathways per se in the pathogenesis of the disease remains unclear. The cellular fate of glucose begins with glucose transport and phosphorylation. Subsequent pathways of glucose utilization include aerobic and anaerobic glycolysis, glycogen formation, and conversion to other intermediates in the hexose phosphate or hexosamine biosynthesis pathways. Abnormalities in each pathway may occur in diabetic subjects; however, it is unclear whether perturbations in these may lead to diabetes or are a consequence of the multiple metabolic abnormalities found in the disease. This review is focused on the cellular fate of glucose and relevance to human type 2 diabetes.

Biological Transport↗
PubMed2004

The -913 G/A glutamine:fructose-6-phosphate aminotransferase gene polymorphism is associated with measures of obesity and intramyocellular lipid content in nondiabetic subjects.

Increases in glutamine:fructose-6-phosphate aminotransferase (GFAT) protein levels directly activate flux through the hexosamine biosynthetic pathway. This pathway has been involved as a fuel sensor in energy metabolism and development of insulin resistance. We screened the 5'-flanking region of the human GFAT gene for polymorphisms and subsequently genotyped 412 nondiabetic, metabolically characterized Caucasians for the two single-nucleotide polymorphisms (SNP) at positions -913 (G/A) and -1412 (C/G) with rare allele frequencies of 42% and 16%, respectively. The -913 G SNP was associated with significantly higher body mass index and percent body fat in men (P = 0.02 and 0.004, respectively), but not in women (P = 0.47 and 0.26, respectively). In the subgroup of individuals (n = 193) who underwent hyperinsulinemic-euglycemic clamp, an association of the -913 G SNP with insulin sensitivity independent of body mass index was not detected. Moreover, the -913 G allele in a group of 71 individuals who had undergone magnetic resonance spectroscopy was associated with higher intramyocellular lipid content (IMCL) in tibialis anterior muscle (4.21 +/- 0.31 vs. 3.36 +/- 0.35; P = 0.04) independent of percent body fat and maximal aerobic power. The -1412 SNP had no effect on percent body fat, insulin sensitivity, or IMCL. In conclusion, we identified two polymorphisms in the 5'-flanking region of GFAT, of which the -913 SNP seems to alter the risk for obesity and IMCL accumulation in male subjects.

Adult↗
PubMed1999

Effect of Saiboku-to, an Oriental Herbal Medicine, on gastric lesion induced by restraint water-immersion stress or by ethanol treatment.

The effect of saiboku-to on gastric lesions induced by restraint water-immersion stress and ethanol has been examined in rats. Thirty minutes after oral administration of saiboku-to, the rats were placed in restraint cages and immersed in water at 23 degrees C for 7 h, or orally administered 99.5% ethanol (1 mL) and placed in normal cages for 1 h. The stress for 7 h or the ethanol treatment for 1h induced erosion in the glandular area of the stomach. Histology showed that the surface epithelial cells were desquamated and part of the lamina propria mucosae was injured. The evaluation of lesion index, the cumulative length of the gastric lesion, on the gross appearance of the stomach, revealed that saiboku-to dose-dependently inhibited both the water-immersion stress-induced gastric erosion and ethanol-induced gastric erosion. To determine whether the anti-erosion effect of saiboku-to was because of a mild irritant effect, saiboku-to or 20% ethanol, which is known as a typical mild irritant, were given orally. After 30 min a strong irritant, 99.5% ethanol, was given orally. Histological examination was performed 30 min after administration of saiboku-to or the mild irritant, and 1 h after administration of the strong irritant. The mild irritant induced a reduction in surface epithelial cells 30 min after administration. Furthermore, the mild irritant protected the stomach against mucosal erosion produced by the strong irritant. Saiboku-to protected the strong irritant-induced erosion without producing mild irritation as observed in stomach treated with 20% ethanol. Pretreatment with saiboku-to also inhibited the decrease in the levels of hexosamine, gastric mucus glycoprotein, induced by the strong irritant. In pylorus-ligated rats, saiboku-to dose-dependently inhibited gastric acid secretion, a gastric aggressive factor. These results suggest that the anti-erosion effect of saiboku-to which is not a mild irritant, involves both inhibition of aggressive factors, such as gastric acid secretion, and augmentation of defensive factors, such as gastric mucus cells.

Animals↗
PubMed2005

Effect of gefarnate on acute gastric mucosal lesion progression in rats treated with compound 48/80, a mast cell degranulator, in comparison with that of teprenone.

We have reported that teprenone (geranylgeranylacetone), an anti-ulcer drug, prevents acute gastric mucosal lesion progression in rats treated once with compound 48/80 (C48/80), a mast cell degranulator, possibly by suppressing mucus depletion, neutrophil infiltration, and oxidative stress in the gastric mucosa. Herein, we examined the preventive effect of gefarnate (geranyl farnesylacetate), an anti-ulcer drug, on acute gastric mucosal lesion progression in rats treated once with C48/80 (0.75 mg/kg, i.p.) in comparison with that of teprenone, because the chemical structure and anti-ulcer action of gefarnate are similar to those of teprenone. Gefarnate (50, 100 or 200 mg/kg) administered orally at 0.5 h after C48/80 treatment, at which time gastric mucosal lesions appeared, reduced progressive gastric mucosal lesions at 3 h dose-dependently. At 3 h after C48/80 treatment, the gastric mucosa had decreased adherent mucus and hexosamine contents and increased myeloperoxdiase (an index of neutrophil infiltration) and xanthine oxidase activities and thiobarbituric acid reactive substances (an index of lipid peroxidation) content. Post-administered gefarnate attenuated all these changes dose-dependently. These preventive effects of gefarnate were similar to those of teprenone at a dose of 200 mg/kg. Post-administered gefarnate did not affect the increases in serum serotonin and histamine concentrations and the decrease in gastric mucosal blood flow at 3 h after C48/80 treatment like teprenone. These results indicate that orally administered gefarnate prevents acute gastric mucosal lesion progression in C48/80-treated rats possibly by suppressing mucus depletion, neutrophil infiltration, and oxidative stress in the gastric mucosa like teprenone.

Animals↗