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At least 1,711 records · Page 95Linked to original sources
PubMed1957

Some aspects of the metabolism of sulfate-S35 and calcium-45 in the metaphyses of immature rats: influence of beta-estradiol benzoate.

Weanling rats were given 2 mg. of 17-beta-estradiol benzoate at weekly intervals for 4 weeks. Twenty-four hours after each intraperitoneal injection of the estrogen 100 microc. of S(35)-sulfate or 11 microc. of Ca(45) was similarly injected. The animals were sacrificed 24 hours after the last dose of isotopes. An effect of estradiol benzoate on calcium metabolism was deduced from the observation that the concentration of calcium in some tissues of the treated rats was higher than the concentration in the tissues of untreated rats. Alkaline extracts of the distal metaphyses of femurs from the estradiol-treated and from control rats, given S(35)-sulfate, were shown by chromatography on an anion exchange resin to contain from 9 to 22 per cent of the S(35) as inorganic sulfate. From similar bone samples, 6 to 21 per cent of the S(35) was removed by decalcification with sodium versenate. Most of the remaining S(35) was associated with uronic acid and hexosamine; on paper chromatograms and paper electrophoretograms S(35) was shown to be part of material which migrated and was metachromatic in the same way as purified chondroitin sulfate. Autoradiograms of the proximal ends of tibiae from the animals given estradiol benzoate showed that both the S(35) and Ca(45) were deposited in the metaphyses in strata. The arrangement of the strata of S(35), however, was different from the arrangement of the strata of Ca(45). This difference in arrangement is interpreted as indicating that most of the S(35) in the metaphysis was derived from the chondroitin sulfate of the cartilage plate which the metaphysis had replaced.

Animals↗
PubMed1956

The incorporation of acetate-1-C14 into cholesterol and fatty acids by surviving tissues of normal and scorbutic guinea pigs.

The synthesis of cholesterol and fatty acids from acetate-l-C(14) by the isolated liver, adrenal, and aorta of scorbutic and pair-fed control guinea pigs has been studied. It was found that ascorbic acid deficiency does not affect the rate of incorporation of C(14)-acetate into cholesterol and fatty acids by the tissues investigated, under our experimental conditions. The relatively high metabolic activity of the artery with regard to cholesterogenesis and lipogenesis was noted. The elevation of serum cholesterol and hexosamine in scurvy has been confirmed.

Acetates↗
PubMed1956

The carbohydrate of gamma-globulin and myeloma proteins.

Various preparations of gamma-globulin homogeneous in the ultracentrifuge showed a similar content of hexose, hexosamine, fucose, and sialic acid. Subfractionation of Fr. II gamma-globulin by zone electrophoresis revealed multiple components of different mean mobilities but containing similar amounts of carbohydrate. Gamma globulin isolated directly from normal serum by zone electrophoresis showed a heavy component in addition to the usual 7 S material. The heavy component (s(20, w) = 19 S) concentrated by preparative ultracentrifugation was found to be considerably richer in carbohydrate than the rest of the gamma-globulin and accounted for small differences in carbohydrate content between different preparations of gamma-globulin. Pathological sera with marked elevation in gamma-globulin showed a carbohydrate-protein ratio for the gamma-globulin similar to that found for the corresponding 7 S fraction in normal serum. This was only partially true of the myeloma proteins with a mobility in the gamma-globulin region. Certain of these proteins showed slight but significant differences. The myeloma proteins of faster mobility (beta-myelomas) contained considerably more carbohydrate. The possible role of these carbohydrates in accounting for some of the mobility and immunological differences in the myeloma proteins is discussed. The pathological proteins found in two cases of macroglobulinemia showed a high carbohydrate content similar to but slightly lower than the normal 19 S component of gamma-globulin.

Blood Proteins↗
PubMed1957

Turnover of S35-sulfate in epiphyses and diaphyses of suckling rats; nature of the S35-labelled compounds.

S(35)-sulfate was injected intraperitoneally- into 7-day-old rats and their long bones were removed after intervals of time. The epiphyses were separated from the diaphyses for analysis. From the diaphyses freed of bone marrow about 82 per cent of the S(35) which they contained was extracted with a 2.5 N solution of sodium hydroxide. More, about 91 per cent of the S(35), was thus extracted from the epiphyses. Dialysis of the extracts against water showed that the fraction of S(35) which was dialyzable decreased rapidly with time. After 1 hour about 80 per cent and 50 per cent of the S(35) in the extracts of diaphyses and epiphyses, respectively were found in the dialysates, after 24 hours about 20 per cent and 4 per cent, and after 120 hours 12 per cent and 1 per cent. Similar values for the S(35) in inorganic sulfate were found when the extracts were chromatographed on an anion exchange resin, dowex-2. The S(35), other than inorganic sulfate, was in the form of bound sulfate, which was released by acid hydrolysis. Uronic acid and hexosamines, primarily galactosamine, were associated with the S(35). Indeed, on paper electrophoretograms and paper chromatograms the major S(35)-labelled component which was seen resembled chondroitin sulfate in its mobility. On the paper chromatograms, also a second S(35)-labelled component with a mobility lower than that of chondroitin sulfate was found. It is unlikely that the latter is a breakdown product of chondroitin sulfate, produced in the course of extraction with the sodium hydroxide solution. In fact, both components were also found in sodium versenate homogenates which had been dialyzed extensively against water. On the basis of these results it is suggested that the greatest part of the S(35)-labelled materials previously demonstrated by autoradiography to be progressively deposited in the metaphyses after 24 hours,-as the concentration of S(35)-sulfate concurrently decreased in the epiphyseal cartilage plates,-are akin to the chondroitin sulfate of the epiphyseal cartilage plates and are derived from the latter.

Animals↗
PubMed1960

Type and group polysaccharides of group D streptococci.

Polysaccharides extracted from cell walls of 4 serological types of Group D streptococci were serologically type-specific. Acid hydrolysates of all 4 contained hexosamine (glucosamine), rhamnose and glucose. A polysaccharide extracted from 2 serological types by either alkaline treatment or mechanical disruption was serologically group-specific. Acid hydrolysates contained glucose and no other single component in comparable amount. The group-specific polysaccharide, which may be of a dextran-like nature, is probably situated wholly or in part at the surface of the streptococcus.

Cell Wall↗
PubMed1961

Preparation of an inhibitor of viral hemagglutination from human erythrocytes.

A material, derived from human erythrocytes and believed to be identical with the receptor site for the myxoviruses, has been obtained in homogeneous form. The method of preparation involves pH adjustment of the stroma, hot phenolic extraction, chloroform-methanol treatment, and ultracentrifugation. The material so obtained possesses a high inhibitory titer to viral hemagglutination (45,000 to 60,000 inhibitory units/mg. against 4 hemagglutination units of Lee strain of influenza virus) and appears to be a glycoprotein containing 22 to 24 per cent sialic acid, 12 per cent hexose, 12 per cent hexosamine, 1 per cent fucose in addition to at least eleven amino acids. The sialic acid probably occupies a terminal position in an oligosaccharide chain extending from the protein peptide chain. The molecular weight is near 30,000-an unusually low value for substances possessing this biological activity. M and N blood group activity also seems to be associated with this protein.

Binding Sites↗
PubMed1961

Metabolic effects of lathyrogenic agents on cartilage in vivo and in vitro.

The effects of lathyrogenic agents in vivo and in vitro are described, in respect to some biochemical indices of cartilage metabolism. Lathyrogenic agents in vivo inhibited the incorporation of radiosulfate into rat epiphyseal cartilage and the isolated chondroitin sulfate. No significant changes in hydroxyproline or hexosamine content of epiphyseal cartilage were found, but there was a marked increase in water content. The content of chondroitin sulfate, measured as uronic acid, was decreased. The importance of taking growth rate differences between control and experimental rats into account in assessing the effects of lathyrogenic agents in vivo is emphasized. In an in vitro system, utilizing fresh calf costal cartilage slices, the presence of low concentrations of lathyrogenic agents markedly affected various metabolic events. The incorporation into cartilage slices of sulfate-S(35), glucose-U-C(14), and glycine-1-C(14) was significantly depressed, as was the production of organic acids, including lactic acid. In general, these effects were more severe under anaerobic conditions. Glutamine restored the activities of the slices treated with lathyrogenic agents to control values obtained in the absence of either lathyrogen or glutamine.

Animals↗
PubMed1961

Preparation and host-reactive properties of endotoxin with low content of nitrogen and lipid.

Endotoxins of low lipid content prepared from S. enteritidis by the aqueous ether method have been further treated to remove bound lipid by non-hydrolytic procedures. Such endotoxins, containing as little as 2 per cent lipid A, were as potent in stimulating a variety of physiological responses as those prepared by the well known phenol-water or Boivin procedures which yield products containing as much as 30 per cent lipid A. To verify the difference in lipid content between the aqueous ether preparations and other types of endotoxins, three different methods of lipid analysis were employed: determination of chloroform-soluble material released by hydrolysis with hydrochloric acid (lipid A) or with acetic acid (lipid W), and estimation of total bound fatty acids. These methods were in accord in showing the magnitude of the difference. No more than one-half of the fatty acids present in endotoxin were associated with the fraction designated lipid A. Methods are described for the preparation of potent endotoxins with analytical values for nitrogen, phosphorus, hexosamine, carbohydrate, and fatty acid which do not differ appreciably from those of the classical, non-toxic, haptenic polysaccharides.

Antitoxins↗
PubMed1972

Connective tissue synthesis by scleroderma skin fibroblasts in cell culture.

Skin fibroblasts from subjects with scleroderma and control subjects were grown in tissue culture to compare the characteristics of connective tissue metabolism. A striking increase in soluble collagen (media hydroxyproline) was observed in eight of nine scleroderma cultures when they were compared with identically handled control cultures matched for the age and sex of the donor and the anatomic site of the donor skin. Glycoprotein content as estimated by hexosamine and sialic acid was also significantly increased in the scleroderma cultures. Estimations of protein-polysaccharide content by uronic acid determinations were low in all cultures and not significantly increased in scleroderma cultures. This report demonstrates the feasibility of using fibroblast cell cultures to study chronic rheumatic and connective tissue disorders. The initial results suggest a net increase in collagen and glycoprotein synthesis in scleroderma fibroblast cultures. The implications of an abnormality of connective tissue metabolism by skin fibroblasts propagated in vitro in the acquired disorder scleroderma are discussed.

Cell Count↗
PubMed1953

Inhibition of Theiler's encephalomyelitis virus (GDVII strain) of mice by an intestinal mucopolysaccharide. II. Purification and properties of the mucopolysaccharide.

A mucopolysaccharide inhibitor of Theiler's GDVII virus has been purified from intestinal tissue of adult mice. The purified material has been shown to consist chiefly of carbohydrate. Following acid hydrolysis of the inhibitor, several amino adds were found to be present. The carbohydrate components shown to be present thus far are galactose, hexosamine, N-acetylhexosamine, methylpentose, hexurornic acid; an indication has been obtained that sedoheptulose is also present. The available evidence strongly suggests that this mucopolysaccharide, and not some other substance present in minute amounts, is the inhibitor of the GDVII virus.

Animals↗
PubMed1952

Physicochemical characterization of pituitary follicle-stimulating hormone.

The physiochemical characteristics of the follicle-stimulating hormone (FSH) from whole sheep pituitary glands have been studied. The hormone behaves as a single protein in electrophoresis, diffusion, and ultracentrifugation. It has an isoelectric point at pH 4.5 and a molecular weight of 67,000 and contains 1.23 per cent hexose and 1.51 per cent hexosamine. The amino acid composition has also been determined in large part. The stability of the hormone to acid and heat has been investigated.

Animals↗
PubMed1952

A study on the structural protein of the vitreous body (vitrosin).

A method is described for the isolation of a structural protein of the vitreous body, which has been named vitrosin. The analyses show that vitrosin is a viscous, thixotropic, fibrous protein. Electron micrographs reveal that vitrosin particles are long fibrils, averaging 250 A in width. The isoelectric point was found to be around pH 5.5 and the shrinkage temperature 60 degrees C. Vitrosin is composed of a protein-carbohydrate complex. It contains cystine and the aromatic amino acids in low quantities. Hexosamine could not be detected in the complex.

Extracellular Matrix↗
PubMedDate not supplied

Role of poly(ADP-ribose) polymerase-1 activation in the pathogenesis of diabetic complications: endothelial dysfunction, as a common underlying theme.

Hyperglycemia-induced overproduction of superoxide by mitochondrial electron-transport chain triggers several pathways of injury involved in the pathogenesis of diabetic complications [protein kinase C (PKC), hexosamine and polyol pathway fluxes, advanced glycation end product (AGE) formation] by inhibiting glyceraldehyde- 3-phosphate dehydrogenase (GAPDH) activity. Increased oxidative and nitrosative stress activates the nuclear enzyme, poly(ADP-ribose) polymerase-1 (PARP). PARP activation, on the one hand, depletes its substrate, NAD+, slowing the rate of glycolysis, electron transport, and ATP formation. On the other hand, it inhibits GAPDH by poly(ADP-ribosy)lation. These processes result in acute endothelial dysfunction in diabetic blood vessels, which importantly contributes to the development of various diabetic complications. Accordingly, hyperglycemia-induced activation of PKC isoforms, hexosaminase pathway flux, and AGE formation is prevented by blocking PARP activity. Furthermore, inhibition of PARP protects against diabetic cardiovascular dysfunction in preclinical models. PARP activation is present in microvasculature of human diabetic subjects. The oxidative/nitrosative stress-PARP pathway leads to diabetes-induced endothelial dysfunction, which may be an important underlying mechanism for the pathogenesis of other diabetic complications (cardiomyopathy, nephropathy, neuropathy, and retinopathy). This review focuses on the role of PARP in diabetic complications and the unique therapeutic potential of PARP inhibition in the prevention or reversal of diabetic complications.

Animals↗
PubMed2005

Liver architecture maintenance by tincture of Crataegus against isoproterenol-induced myocardially infarcted rats.

Myocardial infarction produces significant abnormal liver functioning. In the present study the hepatoprotective effect of tincture of Crataegus (TCR) in myocardially infarcted rats was investigated. The oral administration of TCR to rats for 30 days afforded good protection against isoproterenol-induced alterations in tissue marker enzymes of liver injury like alanine aminotransferase, aspartate aminotransferease, lactate dehydrogenase, and alkaline phosphatase and in protein-bound carbohydrates like hexose, hexosamine, fucose, and sialic acid. The protective effect of TCR was further supported by the reversal of isoproterenol-induced histological changes in the liver. The results suggest that TCR, which can protect the heart and circulatory system, can also be hepatoprotective and thereby maintain the near normal architecture of liver tissue.

Alanine Transaminase↗
PubMed1996

A phosphoglucomutase-like gene essential for the optimal expression of methicillin resistance in Staphylococcus aureus: molecular cloning and DNA sequencing.

We describe here the cloning and sequencing of a new auxiliary gene identified by Tn551 insertional mutagenesis of the highly and homogeneously methicillin-resistant Staphylococcus aureus strain COL. The insertionally inactivated mutant RUSA315 had intact mecA and normal amounts of PBP2A, but drastically reduced antibiotic resistance (drop in methicillin MIC from 1600 to 1.5 micrograms ml-1), a unique heterogeneous phenotype, and a compositional change in the cell wall characterized by the complete disappearance of the unsubstituted disaccharide pentapeptide from the peptidoglycan. Cloning in E. coli followed by sequencing located the Tn551 insert omega 720 in an open reading frame of 451 codons, provisionally called femR315, defining a polypeptide with a deduced amino acid sequence that showed over 26% sequence identity and 57% overall sequence similarity with the phosphoglucomutase (PGM) gene of E. coli. The Tn551 insertion site of a previously described mutant 12F (femD) also lies in the same gene as femR315. The wild-type form of femR315 subcloned in a shuttle vector fully restored expression of high level (parental) methicillin resistance in mutant RUSA315. The exact biochemical function of femR315 is not known. However, enzymes similar to PGM catalyze the isomerization of hexose and hexosamine phosphates leading to the formation of glucosamine-1-P, which is an obligate precursor in the biosynthesis of UDP-N-acetylglucosamine (UDP-NAGA). We propose that the suppression of methicillin resistance in RUSA315 is related to some functional or quantitative abnormality of UDP-NAGA metabolism.

Amino Acid Sequence↗
PubMed1990

Decrease of liver energy charge, ATP and glutathione at concomitant intraarterial administration of adriamycin and degradable starch microspheres in rat.

Adriamycin (Adr) and degradable starch microspheres (DSM) were infused either combined or each separately into the hepatic artery in rats. Liver ATP, GTP, UDP-glucuronic acid, UDP-N-acetyl-hexosamine and energy charge and glutathione were decreased 20 min later with combined treatment but not by Adr or DSM when infused alone. the nucleotide levels were normalized 60 min after the combined treatment. After one week, the Adr rats showed a less weight gain than controls. The Adr + DSM rats lost weight. Only minor changes were found in the livers at microscopical examination at this time.

Adenosine Triphosphate↗
PubMed1978

Complex carbohydrate breakdown in the human colon.

Concentrations of water-soluble high- and low-molecular-weight carbohydrates were determined in the intestinal contents of four human subjects who had died accidentally. In all four subjects, concentrations of high-molecular-weight carbohydrate were lower throughout the colon than in the ileum. In some subjects, similar but less dramatic differences were also found with low-molecular-weight carbohydrate. Components of both high- and low-molecular-weight peaks included neutral sugars such as rhamnose, galactose, mannose, xylose, and arabinose, which are found in many plant polysaccharides. Components characteristic of mucins (fucose, hexosamines, and sialic acids) were also detected. These results indicate that dietary fiber and mucin are degraded in the human colon.

Carbohydrate Metabolism↗
PubMed2000

Decreased UDP-GlcNAc levels abrogate proliferation control in EMeg32-deficient cells.

The hexosamine pathway provides UDP-N:-acetylhexosamine donor substrates used in cytosolic and Golgi-mediated glycosylation of proteins and for formation of glycosylphosphatidylinositol (GPI) anchors, which tether proteins to the outer plasma membrane. We have recently identified the murine glucosamine-6-phosphate (GlcN6P) acetyltransferase, EMeg32, as a developmentally regulated enzyme on the route to UDP-N:-acetylglucosamine (UDP-GlcNAc). Here we describe embryos and cells that have the EMeg32 gene inactivated by homologous recombination. Homozygous mutant embryos die at around embryonic day (E) 7.5 with a general proliferative delay of development. In vitro differentiated EMeg32(-/-) ES cells show reduced proliferation. Mouse embryonic fibroblasts (MEFs) deficient for EMeg32 exhibit defects in proliferation and adhesiveness, which could be complemented by stable re-expression of EMeg32 or by nutritional restoration of intracellular UDP-GlcNAc levels. Reduced UDP-GlcNAc levels predominantly translated into decreased O-GlcNAc modifications of cytosolic and nuclear proteins. Interestingly, growth-impaired EMeg32(-/-) MEFs withstand a number of apoptotic stimuli and express activated PKB/AKT. Thus, EMeg32-dependent UDP-GlcNAc levels influence cell cycle progression and susceptibility to apoptotic stimuli.

Acetyltransferases↗