Glycosaminoglycan content in tissues and body fluids of rats treated with atherogenic diet.

An increase of total glycosaminoglycan content in aortic wall and liver as well as changes in the concentration of glycosaminoglycan fractions in aorta, skin, liver, and blood serum were found in white rats fed with atherogenic diet. Urinary excretion of glycosaminoglycans was increased in experimental animals.     

Pyridoxine and atherosclerosis: role of pyridoxine in the metabolism of lipids and glycosaminoglycans in rats fed normal and high fat, high cholesterol diets containing 16% casein

The effect of administration of low and high doses of pyridoxine on the metabolism of lipids and glycosaminoglycans has been studied in rats fed normal and high fat, high cholesterol diets. Low doses of pyridoxine (0.005 mg/100 g body weight) caused increased concentrations, of cholesterol and triglycerides in the serum and aorta in animals fed normal and high fat, high cholesterol diets. Administration of high doses of pyridoxine (5.0 mg/100 g body weight) caused decrease in the concentration of these lipids in these tissues except in the case of the aorta in the animals fed a normal diet. Low doses of pyridoxine generally caused a decrease in the concentration of many glycosaminoglycan fractions in the aorta in rats fed normal and high fat, high cholesterol diets, whilst high doses caused an increase. The activity of glucosaminephosphate isomerase (glutamine-forming) and UDPglucose dehydrogenase, both key enzymes in the biosynthetic pathway of glycosaminoglycans, decreased in rats given low doses of pyridoxine and increased in rats given high doses. The activity of many enzymes concerned with degradation of glycosaminoglycans--hyaluronoglucosidase, beta-glucuronidase, beta-N-acetylglucosaminidase, aryl sulphatase, and cathepsin D--generally increased in rats fed low doses of the pyridoxine and decreased in those given high doses. The concentration of hepatic 3'-phosphoadenosine-5'-phosphosulphate, and the activity of the sulphate-activating system and of aryl sulphotransferase decreased when the dose of pyridoxine was low and increased when the dose was high.     

Amino acid supplementation of methanol-grown dried microbial cells in diets for young chicks

Growth rates and efficiency of food conversion of young chicks fed on diets marginally limiting in total nitrogen and containing 150 g/kg diet of flash-dried microbial cells (MC) with and without amino acid supplements, were measured in three experiments. Performance of these animals was compared with that of groups fed on a methioninefortified soya bean meal (SBM) control diet. In all experiments, chicks fed on the SBM control diet grew faster and were more efficient than chicks fed on the basal unsupplemented MC diet. In Experiment 1, arginine supplementation markedly enhanced weight gain and efficiency of food utilisation of chicks offered the basal MC diet; methionine had no effect. The second experiment demonstrated that a supplement containing methionine, arginine and tryptophan was more effective in augmenting the nutritional value of MC than either methionine with arginine or tryptophan with arginine. In the final experiment, weight gain and food intake of chicks fed on MC with supplements of arginine, methionine and tryptophan were increased markedly by additions of lysine and glutamic acid but not by addition of lysine alone. In all experiments, performance of animals in MC supplemented groups was lower than that of animals fed on the SBM control diet.     

Effects of isoflavones containing soy protein isolate compared with fish protein on serum lipids and susceptibility of low density lipoprotein and liver lipids to in vitro oxidation in hamsters

The effects of dietary soy protein isolate (SPI), ethanol-extracted SPI (E-SPI) low in isoflavones, and fish protein (FP) on the concentration of blood lipids and the susceptibility of low density lipoprotein (LDL) to copper-induced oxidation were compared in male golden Syrian hamsters fed a moderate hypercholesterolemic semi-purified diet for 10 weeks. SPI, E-SPI, and FP were incorporated into the isonitrogenous experimental diets as protein sources. The SPI group exhibited significantly lower serum total cholesterol concentration compared with the E-SPI group (P < 0.05) and the FP group (P < 0.01). Both the SPI and E-SPI groups showed lower LDL cholesterol (P < 0.001 and P < 0.05, respectively) and less LDL apolipoprotein B (P < 0.01) compared with the FP group. The distribution pattern of serum lipoprotein cholesterol fractions of the SPI and E-SPI groups were similar to each other, but different from that of the FP group. The lysine/arginine ratio of the three diets was significantly correlated with serum total cholesterol concentration (r = 0.462, P = 0.023). The resistance of LDL to copper-induced oxidation was greater in the SPI group than in the E-SPI and FP groups as assessed by the lower concentrations of thiobarbituric acid-reactive substances (TBARS) and the longer lag time required for the formation of conjugated dienes (P < 0.01). Livers of hamsters fed the FP diet had a higher amount of TBARS than those of hamsters fed SPI (P < 0.01) and E-SPI (P < 0.05) diets. The SPI diet showed sparing effects on alpha-tocopherol contents in both serum and liver. It seems likely that soy isoflavones protect the circulating and membrane lipids by sparing alpha-tocopherol and endogenous antioxidants.     

Glycoproteins and glycolipids of oxyntic cell microsomes I. Glycoproteins: Carbohydrate composition,analytical and preparative fractionation

Isotopically-labeled sugars were incorporated into glycoproteins of isolated bullfrog gastric mucosa. The majority of the label was found in gastric microsomal fractions which were shown to contain membranes derived from the oxyntic cell tubular membrane system and were not significantly contaminated with mucus. The tubular membranes contained exceptionally large quantities of carbohydrate (approx. 260 μg/mg protein). Most of the sugar (73%) was associated with protein in the following molar ratios: hexose, 1.0: fucose, 0.42; hexosamine, 0.62; sialic acid, <0.02. The remaining sugar, predominantly hexose, could be extracted into lipid solvents and was presumably glycolipid.Gastric microsomes were dissolves in sodium dodecyl sulfate and subjected to acrylamide gel electrophoresis and Sephadex G-200 fractionation. The latter preparative procedure yielded several molecular weight classes, each of which contained different sets of proteins and/or glycoproteins; however, the molar ratios of the sugars found in the two carbohydrate containing classes were quite similar.Significant quantities of carbohydrate were also found in gastric microsomal fractions from other species, e.g. pig and rabbit. Furthermore, characteristic proteins and glycoproteins were not present in tadpole gastric microsomes until the later stages of metamorphosis when HCl secretory capability had been established. The above findings suggest that glycoproteins may play an important role in oxyntic cell functions; the possibility of a membrane protective role is discussed.     

Effect of magnesium deficiency on the metabolism of glycosamino-glycans in rats

Magnesium deficiency in rats has significant effect on the concentration of different glycosaminoglycans in the tissues, the nature of the change being different in different tissues. Total glycosaminoglycans, chondroitin-4-sulphate + chondroitin-6-sulphate and dermatan sulphate increased in the aorta while hyaluronic acid, heparan sulphate and heparin decreased. In the liver, total glycosaminoglycans, hyaluronic acid, chondroitin-4-sulphate + 6-sulphate and heparin decreased while total glycosamino-glycans and all the glycosaminoglycan fractions increased in the heart. In the kidney, total glycosaminoglycans showed no significant alteration, hyaluronic acid and heparin decreased while chondroitin-4-sulphate + 6-sulphate increased. Activity of biosynthetic enzymesviz. glucosamine-o-phosphate isomerase and UDPG-dehydrogenase showed decrease in the liver. The concentration of 3’-phosphoadenosine 5’-phosphosulphate, activity of sulphate activating system and sulphotransferase were also similarly altered in the liver in magnesium deficiency.     

Observation on Plasma Free Amino Acids of Cow under Different Feeding

The influence of nutritional alteration to the plasma amino acid patterns in cows was investigated. The ratio of the essential to nonessential amino acids (E/N) at 6 months after change of diet was higher in the group fed a high protein and low energy diet than the group fed a moderate protein and moderate energy diet (the control group). The total nonessential amino acid levels decreased in the former group. The decrease was due to lower values for glycine, alanine and glutamic acid.

On the other hand, the E/N radio was lower in groups fed low protein diets than in the control group and total essential amino acid levels were lower in the former group than in the control group. The decrease was due to lower values for valine, threonine and arginine. Conversely, the higher values in glycine, serine and proline than those in the control group were observed.     

Dietary manganese affects the concentration, composition and sulfation pattern of heparan sulfate glycosaminoglycans in Sprague-Dawley rat aorta

We examined the effect of dietary Mn on the composition and structure of heparan sulfate (HS) glycosaminoglycans (GAGs) of rat aorta. Animals were randomly assigned to either a Mn deficient (MnD), adequate (MnA) or supplemented (MnS) diet (Mn<1, 10–15 and 45–50 ppm, respectively). After 15 weeks, aortic tissue GAGs were isolated with papain digestion, alkaline borohydride treatment and anion-exchange chromatography. Cellulose acetate electrophoresis and treatment of the fractions with specific lyases revealed the presence of three GAG populations, i.e. hyaluronan (HA), heparan sulfate (HS) and galactosaminoglycans (GalAGs). Disaccharide composition of the HS fractions was determined by HPCE following treatment with heparin lyases I, II and III. In MnS aortas we observed increased concentration of total GalAGs and decreased concentration of HS and HA, when compared to MnA aortas. Aortas from MnD and MnA rats appeared to have similar distribution of individual GAGs. Heparan sulfate chains of MnS aortas contained higher (41%) concentration of non-sulfated units compared to MnA ones. Variable amounts of trisulfated and disulfated units were found only in MnD and MnA groups but not in MnS. Our results demonstrate that HS biosynthesis in the rat aorta undergoes marked structural modifications that depend upon dietary Mn intake. The reduced expression and undersulfation of HSPGs with Mn supplementation might indicate a reduced ability of vascular cells to interact with biologically active molecules such as growth factors. Alterations in cell-membrane binding ability to a variety of extracellular ligands might affect signal-transduction pathways and arterial functional properties.     

Biochemical and immunological characterization and the synthesis of rat intestinal glycoproteins following the induction of rapid synchronous vitamin A deficiency

Glycoproteins and proteins were extracted from segments or scrapings of the intestine in tube-fed, vitamin-A-deficient and control rats on the eight day after withdrawal of retinoic acid from the diet by using either 1% sodium dodecyl sulfate (SDS) or aqueous 5 mM EDTA (pH 7.4). They were then fractionated on columns of Sepharose 4B. Water-soluble peak I material contained large (M_r > 10⁶; S₂₀ = 11.7) glycoprotein aggregates which were rich in hexose, fucose and sialic acid. These aggregates dissociated into several non-identical glycoprotein and protein subunits upon treatment with dithiothreitol. The protein matrix was rich in threonine, valine, proline, serine, glutamate and aspartate. Peak II consisted of smaller proteins and glycoproteins, the latter with much lower carbohydrate content. Some peak II glycoproteins also dissociated into subunits in the presence of dithiothreitol. Peak III consisted mainly of a heterogenous assortment of proteins, including some glycoproteins of low carbohydrate content. Antibodies either to peak II or to peak III reacted both with peaks II and III but not with peak I.The total weight, carbohydrate composition of glycoproteins and the ratio of carbohydrate to protein in the total extract or in each of the three fractions were not significantly affected in vitamin A deficiency despite decreased incorporation of all labeled precursors. Rather, the relatively lower incorporation (approx. 0.8) of radioactive sulfate, D-glucosamine and L-fucose into total SDS-soluble duodenal glycoproteins of vitamin-A-deficient rats could be explained on the basis of a reduced prevalence of goblet cells alone. In contrast, the relative incorporation rate of L-fucose into peak I, but not into peaks II and III, ranged from 0.25 to 0.45, less than expected on the basis of fewer goblet cells alone. The incorporation of radioactive threonine into all protein fractions was reduced to 60% of normal in vitamin A deficiency. Thus, the well established observation that intestinal tissue of vitamin-A-deficient rats synthesizes high molecular weight glycoproteins poorly might be due to several interacting factors: (1) a reduced prevalence of goblet cells, (2) a lower rate of protein synthesis, (3) a lack of retinyl phosphate for the formation of mannosyl or other carbohydrate derivatives, and (4) secondary, and as yet undefined, cellular changes which preferentially reduce the rate of synthesis of high molecular weight fucose- and sialic-acid-enriched glycoproteins.     

Lysine and arginine requirements of juvenile Asian sea bass (Lates calcarifer)

Two separate experiments were conducted to determine the dietary requirements of juvenile Asian sea bass Lates calcarifer Bloch for lysine and arginine. Fish (average initial weight: lysine experiment, 13.12 ± 0.12 g; arginine experiment, 2.56 ± 0.13 g) were given amino acid test diets for 12 weeks containing fish meal, zein, squid meal, and crystalline amino acids. Each set of isonitrogenous and isocaloric test diets contained graded levels of L ‐lysine or L ‐arginine. The feeding rate in the lysine experiment was at 4–2.5% of the body weight day^?1, while in the arginine experiment it was at 10–4% of the body weight day^?1. The fish (20 per tank, lysine experiment; 15 per tank, arginine experiment) were reared in 500‐L fibreglass tanks with continuous flowthrough sea water at 27 °C and salinity of 31 ppt in the lysine experiment and at 29 °C and salinity of 29 ppt in the arginine experiment. The experiments were in a completely randomized design with two replicates per treatment. Survival was high in fish given adequate lysine or arginine. Mean percentage weight gains were significantly different in fish fed varying levels of lysine or arginine. Fish fed high levels of L ‐arginine suffered high mortalities. No significant differences were obtained in the feed efficiency ratios (FER, g gain g^?1 feed) of fish fed graded lysine, although the values tended to increase as the dietary lysine level was increased up to the requirement level. In contrast, in the arginine experiment, significant differences in FER of fish among treatments were obtained; the highest FER was observed in fish fed the diet containing an optimum arginine level. On the basis of the growth response, survival, and FER, the lysine and arginine requirements of juvenile Asian sea bass were estimated to be 20.6 g kg^?1 dry diet (4.5% protein) and 18.2 g kg^?1 dry diet (3.8% protein), respectively. These data will be useful in the further refinement of practical diet formulations for the Asian sea bass.     

ISOLATION AND DETERMINATION OF NON-DIFFUSIBLE SIALOFUCOHEXOSAMINOGLYCANS DERIVED FROM BRAIN GLYCOPROTEINS AND THEIR ANATOMICAL DISTRIBUTION IN BOVINE BRAIN

Abstract— Glycoproteins in brain tissue were assayed by determining the amount of N-acetylneuraminic acid (NANA), hexosamine, hexose, and fucose present in glycopeptides released by the proteolytic action of papain on the defatted protein residue that remains after treatment of the sample with chloroform-methanol (2:1 and 1:2, v/v). Diffusible and non-diffusible glycopeptides (sialofucohexosaminoglycans) were released by proteolysis. The procedure demonstrated that successive treatment of brain tissue with chloroform-methanol (2:1, v/v) and chloroform-methanol (1:2, v/v) removed all of the gangliosides present in the tissue. A 1 hr autolysis of rat brain tissue had no effect on the amount of glycopeptides recovered from the tissue. The carbohydrate composition of the non-diffusible sialofucohexosaminoglycans was also unaffected. Areas of the brain that are enriched in neuronal cell bodies contained a higher concentration of gangliosides and glycoproteins than areas that consist largely of myelinated fibre tracts. On the other hand, there was a greater concentration of glycoprotein relative to that of gangliosides in areas that consist predominately of myelinated fibre tracts and glia than in areas enriched in neuronal cell bodies. The concentration of non-diffusible sialofucohexosaminoglycans in whole bovine brain was less than that in whole rat brain. The non-diffusible sialofucohexosaminoglycans from whole bovine brain contained less fucose and NANA per mole of hexosamine and hexose than non-diffusible sialofucohexosaminoglycans isolated from whole rat brain. The non-diffusible sialofucohexosaminoglycans isolated from bovine cerebral white matter were lower in fucose and NANA content per mole of hexose and hexosamine than those isolated from other brain areas. It is suggested that the fucose and NANA content of the non-diffusible sialofucohexosaminoglycans associated with myelinated axons and (or) glia is less than that of the non-diffusible sialofucohexosaminoglycans associated with the nerve cell body.     

Subcellular and anatomical distribution in rat brain of glycoproteins that contain mannose-rich heteropolysaccharide chains

Mannose-rich glycopeptides derived from brain glycoproteins were obtained by proteolysis of bovine brain tissue or subcellular fractions derived from rat brain tissue. The dialyzable mannose-rich glycopeptides were isolated by colum electrophoresis and gel flitration. These glycopeptides contained, on the average, six mannose and two N-acetylglucosamine residues with variable amounts of fucose and galactose. Over 50% of the mannose-rich glycopeptides of rat brain were localized in the microsomal and synaptosomal fractions; myelin and the soluble fraction contained lesser amounts. None was recovered from the mitochondria. The amount, per mg protein, of mannose-rich oligosaccharide chains in the myelin exceeded the concentration found in the microsomal and synaptosomal fractions. The concentration of mannose-rich glycopeptides derived from glycoproteins was 50% higher in white matter than in gray. On the other hand, the non-dialyzable and acidic sialoglycopeptides showed a three-fold enrichment in gray matter compared to white. The relatively lower ratio of sialoglycopeptides to mannose-rich glycopeptides observed in white matter (2.5) compared to gray matter (6.9) is reflected in the lower value for the ratio in myelin (1.1) compared to synpatosomes (2.1). Although glycoproteins that contain mannose-rich oligosaccharide chains are present in the nerve cell and its terminals, these glycoproteins appear to be relatively enriched in myelin and/or glial membranes.     

Effects of dietary di(2-ethylhexyl)phthalate, a putative endocrine disrupter, on enzyme activities involved in the metabolism of tryptophan to niacin in rats

We have reported that the conversion ratio of tryptophan to niacin increased with increasing dietary concentration of di(2-ethylhexyl)phthalate (DEHP); the conversion ratio was about 2.0% in the control rat, which increased by about 30% in the rat fed with 3.0% DEHP diet. In this study, we investigated whether this abnormal increase in the conversion ratio by DEHP occurred through the alteration of the enzyme activities involved in the metabolism of tryptophan to niacin. Rats were fed with a diet containing 0%, 0.1%, 0.5%, or 1.0% DEHP for 21 days. The nine kinds of enzyme activities involved in the biosynthesis and catabolism in the liver and kidney were measured. Based on previous findings that the formation of quinolinic acid and its' metabolites significantly increased with DEHP administration, we proposed that the activity of 2-amino-3-carboxymuconate-6-semialdehyde decarboxylase would be inhibited by DEHP intake. However, we found that the activities in the liver and kidney did not decrease in the rat fed with DEHP-containing diet. We discuss the discrepancy between the metabolite results and the enzyme activities.     

Effects of dietary protein and amino acid levels on the expression of selected cationic amino acid transporters and serum amino acid concentration in growing pigs

The absorption of lysine is facilitated by leucine, but there is no information regarding the effect of crude protein, lysine and leucine levels on the expression of cationic amino acid transporters in pigs. Therefore, an experiment was conducted with 20 pigs (14.9 +/- 0.62 kg initial body weight) to evaluate the effect of two protein levels, and the content of lysine, threonine, methionine and leucine in low crude protein diets on the expression of b(0,+) and CAT-1 mRNA in jejunum, Longissimus dorsi and Semitendinosus muscles and serum concentration of amino acids. Treatments were as follows: (i) wheat-soybean meal diet, 20% crude protein (Control); (ii) wheat diet deficient in lysine, threonine and methionine (Basal diet); (iii) Basal diet plus 0.70% L-lysine, 0.27% L-threonine, 0.10% DL-methionine (Diet LTM); (iv) Diet LTM plus 0.80% L-leucine (Diet LTM + Leu). Despite the Basal diet, all diets were formulated to meet the requirements of lysine, threonine and methionine; Diet LTM + Leu supplied 60% excess of leucine. The addition of lysine, threonine and methionine in Diet LTM increased the expression of b(0,+) in jejunum and CAT-1 in the Semitendinosus and Longissiums muscles and decreased CAT-1 in jejunum; the serum concentration of lysine was also increased (p < 0.01). Further addition of L-leucine (Diet LTM + Leu) decreased the b(0,+) expression in jejunum and CAT-1 in the Longissimus dorsi muscle (p < 0.05), increased the serum concentration ofleucine and arginine and decreased the concentration of isoleucine (p < 0.05). Pigs fed the Control diet expressed less b(0,+) in jejunum, and CAT-1 in the Semitendinosus and Longissiums muscles expressed more CAT-1 in jejunum (p < 0.05) and had lower serum concentration ofisoleucine, leucine and valine (p < 0.05), but higher lysine concentrations (p < 0.01) than those fed Diet LTM. These results indicated that both, the level and the source of dietary amino acids, affect the expression of cationic amino acid transporters in pigs fed wheat-based diets.     

Role of dietary lysine, methionine, and arginine in the regulation of hypercholesterolemia in rabbits

These experiments were conducted to see whether the hypercholesterolemia produced by a diet enriched in lysine (Lys) and methionine (Met) can be reproduced by feeding these amino acids separately, and whether dietary arginine (Arg) counteracts their hypercholesterolemic effects. Another aim was to investigate the mechanisms involved in modulations of serum cholesterol levels by these amino acids. The results of this study, which were in agreement with the results of earlier experiments in our laboratory, showed that feeding a low-fat, cholesterol-free, semipurified amino acid diet enriched with Lys + Met to rabbits caused a marked increase in serum total and low density lipoprotein cholesterol and apolipoprotein B levels, whereas a similar diet enriched in essential ketogenic amino acids (EketoAA) resulted in a more moderate increase in these parameters. Supplementing the diet with either Lys or Met alone was also less effective in inducing hypercholesterolemia than increasing levels of both amino acids. Dietary Arg partially counteracted the hypercholesterolemic effect of Lys + Met but not that of the EketoAA or of Lys and Met fed separately. The growth performance of rabbits fed the Lys + Met diet was inferior to that of those fed the other diets. Liver total phospholipid levels and the ratio of phosphatidylcholine to phosphatidylethanolamine were higher in rabbits fed the Lys + Met-enriched diet than in those animals fed a diet in which Arg was supplemented. In conclusion, our results indicate that high levels of both Lys and Met are needed to cause a maximum elevation of serum cholesterol and that the moderately antihypercholesterolemic effect of Arg is seen only when both amino acids are supplemented. They also suggest that these essential amino acids may affect cholesterol metabolism partly through alteration of liver phospholipids.     

Changes in Glycoprotein Metabolism in the Cerebral Cortex Following First Exposure of Dark-reared Rats to Light

Abstract: The level of incorporation of [³H]fucose or [³H]lysine into subcel-lular fractions of the visual and motor cortices of 50-day-old dark-reared (D) and light-exposed (L) rats was determined. No differences were found between D and L rats in the incorporation of either precursor into subcellular fractions of the motor cortex, or in any fraction of the visual cortex except the synaptic-membrane fraction. After a 3-h light exposure the incorporation of [³H]fucose into the visual cortex synaptic-membrane fraction was elevated (L/D = 136%). Incorporation of [³H]lysine was elevated in the visual cortex synaptic-membrane fraction of L compared to D rats after a 1-h exposure (L/D = 118%). However, after a 3-h exposure the incorporation was depressed in this fraction (L/D = 79%). No differences could be found in the levels of activity of fucosyl transferase following first exposure to light but dark-rearing itself resulted in increased enzyme activity in the motor cortex compared to normal controls. First exposure of 20-day-old dark-reared rats to light led to an increase in the incorporation of [³H]fucose into soluble glycoproteins of both the visual and motor cortex and into particulate glycoproteins of the visual cortex only. These results are in contrast with those found with 50-day-old animals and suggest that the effects of light-exposure on [³H]fucose incorporation may be age-dependent.     

Preparation and properties of sialomucopolysaccharides obtained from rat brain

Sialomucopolysaccharides were released from the defatted protein residue by the proteolytic action of papain after extraction of rat whole brains with chloroform-methanol (2:1, v/v). Further purification is achieved by dialysis to remove low-molecular-weight fragments and by precipitation of nucleic acids and glucuronic acid-containing mucopolysaccharides by treatment with cetylpyridinium chloride. Gel filtration of the sialomucopolysaccharides through Sephadex G-200 removes the major portion of the impurities that absorb light in the ultraviolet region. The sialomucopolysaccharides were fractionated on DEAE-Sephadex to yield a population of sialomucopolysaccharides that show an increase in N-acetylneuraminic acid content and a decrease in fucose content as the concentration of chloride required to elute the individual components is increased. On gel filtration on Sephadex G-200, those sialomucopolysaccharide molecules rich in N-acetylneuraminic acid and poor in fucose appear to be larger molecules than those rich in fucose and poor in N-acetylneuraminic acid. A structure is proposed in which all sialomucopolysaccharide molecules are assumed to possess the same repeating unit consisting of hexosamine and hexose. The molecules differ from each other in the number of fucose and N-acetylneuraminic acid residues attached to the basic structure. Most of the hexosamine is present as glucosamine, although one fraction was obtained that appeared to contain galactosamine. Most of the hexose present is accounted for as galactose and mannose, although small amounts of glucose were found in some fractions. Methods of analysis for the N-acetylneuraminic acid and hexosamine components of the sialomucopolysaccharides were defined.     

Interrelationship of Growth and Plasma Amino Acid Concentration in the Chick Fed Casein Diets as Influenced by Dietary Protein and Amino Acid Levels

Chicks fed a 20% casein-sucrose diet showed severe growth depression, but dietary supplementation with 0.7% arginine-HCl, 0.35% glycine and 0.35% dl-methionine improved the growth rate to almost that of chicks fed a practical diet. Chicks fed high protein diets containing 64% casein showed normal growth, irrespective of the supplementation with such amino acids. Plasma arginine concentration of growth-retarded chicks was significantly lower than that of normal chicks. Plasma threonine/arginine ratio was negatively correlated with the growth rate of the chicks, the ratio of normal chicks being 3 ~ 4 whereas that of growth-retarded chicks was about 24. No lysine-arginine antagonism occurred-under high casein feeding.     

Effect of Individual Essential Amino Acid-Devoid Diets on the Activities of Liver Urea Cycle Enzymes in Rats

The activities of all urea cycle enzymes (carbamyl phosphate synthetase, ornithine trans- carbamylase, argininosuccinate synthetase, argininosuccinase and arginase) have been determined in the liver of rats forcibly fed diets lacking in individual essential amino acids from amino acid mixture simulating to a casein. In general, these enzyme activities (units/g liver and total units/body wt) in rats fed the single essential amino acid-devoid diet decreased as compared with those activities in animals fed complete diet, but their decreases were not as large as those observed in group of all amino acid-devoid diet. The degree of decrease in these enzyme activities differed somewhat from each other in individual enzymes and each essential amino acie-devoid groups. In contrast, in rats fed the arginine devoid diet, the activities (total units/body wt) of all enzymes expect the case of arginase increased more than those in the group of complete diet.     

The carbohydrate components of arterial basement-membrane-like material. Studies on rabbit aortic myomedial cells in culture.

The carbohydrate composition of arterial basement-membrane-like material was investigated. Basement-membrane-like material was isolated from cultures of aortic myomedial cells by a sonication/differential-centrifugation technique. Purified basement-membrane-like material contained a total of 5% sugars, comprising glucose, galactose, mannose, fucose, sialic acid, glucosamine and galactosamine in the approximate molar proportions 3.2:3.5:3.4:3.2:1:5.5:3.1. In addition, small amounts of xylose were found. Analyses for uronic acid showed that glycosaminoglycans comprised about 1% of isolated basement-membrane-like material. The carbohydrate composition indicated the presence of complex-type oligosaccharides in addition to hydroxylysine-linked disaccharides. [3H]Glucosamine-labelled glycopeptides obtained by proteinase digestion and gel filtration were resistant to endo-beta-N-acetylglucosaminidase D, but more than 10% were susceptible to alpha-mannosidase, demonstrating the presence of high-mannose-type oligosaccharides. The distribution of carbohydrates among peptides of basement-membrane-like material on sodium dodecyl sulphate/polyacrylamide-gel electrophoresis was investigated after labelling with [3H]mannose, [3H]fucose, [3H]galactose and [3H]glucosamine. Among peptides that appeared to carry carbohydrates were a proteoglycan(s) and seven glycoproteins in the molecular-weight range 120 000-700 000.