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PubMed1986

Purification and Properties of a Novel Xanthan Depolymerase from a Salt-Tolerant Bacterial Culture, HD1.

A novel xanthan depolymerase (endo-beta-1,4-glucanase) was isolated from a salt-tolerant bacteria culture (HD1) grown on xanthan. The depolymerase was purified 55-fold through chromatography on ion-exchange and molecular sieve columns, including high-performance liquid chromatography. The purified enzyme fraction was homogeneous as judged by polyacrylamide gel electrophoresis. The molecular weight of this enzyme is 60,000. Optimum pH and temperature for xanthan depolymerase activity were around 5 and 30 to 35 degrees C, respectively. The enzyme was not stable at a temperature higher than 45 degrees C. The activation energy calculated from an Arrhenius plot was 6.40 kcal (26.78 kJ). The enzyme molecule contains no sugar moiety. The amino acid composition of the enzyme protein was determined. Xanthan depolymerase cleaves the endo-beta-1,4-glucosidic linkage of the xanthan molecule, freeing reducing groups of some sugars and decreasing viscosity of the polymer solution. Only the backbones of beta-1,4-linked glucans with side chains or other substituents were cleaved. No monosaccharide was produced by the action of this enzyme. The oligosac-charide(s) in the low-molecular weight fraction consisted of 15 to 58 monosaccharide units. The enzymic reaction resulted in the decrease in weight-average molecular weight of xanthan from 6.5 x 10 to 8.0 x 10 in 0.5 h. This enzyme alone could not degrade xanthan to a single or multiple pentasaccharide unit(s). Results suggest that there may be regions inside the xanthan molecule that are susceptible to the attack of this enzyme. Xanthan depolymerase activity was not inhibited by many chemicals, including thiols, antioxidants, chlorinated hydrocarbons, metal-chelating agents, and inorganic compounds, except ferric chloride and arsenomolybdate. Many biocides were tested and found not to be inhibitory. Conditions used in enhanced oil recovery operations, i.e., the presence of formaldehyde, Na(2)S(2)O(4), 2,2-dibromo-3-nitrilopropionamide, and an anaerobic environment, did not inhibit xanthan depolymerase activity.

Journal Article↗
PubMed1999

Composition and enzymatic activity of the extracellular matrix secreted by germlings of botrytis cinerea.

Germlings of Botrytis cinerea, an important fungal pathogen of plants, produce an extracellular matrix (ECM), or ensheathing film, that serves, in part, in their attachment (R. P. Doss, et al., Appl. Environ. Microbiol. 61:260-265, 1995). The composition of this film has been ascertained by using samples obtained by growing germlings on a glass surface, removing the fungal mycelium by vigorous washing, and collecting the tightly attached film by scraping the substratum with a razor blade. Slightly over half of the dry weight of the ECM was found to be carbohydrates (about 20%), proteins (about 28%), and lipids (about 6%). Hydrolysis of the carbohydrate portion of the ECM revealed that glucose was the most prominent monosaccharide present, comprising about 60% of the total monosaccharides. Also present were mannose (about 35%) and myo-inositol (about 5%). The proteinaceous fraction of the ECM was made up of a number of polypeptides separable by polyacrylamide gel electrophoresis. The lipid fraction of the ECM, analyzed by thin-layer chromatography, was made up of several simple lipid components, including free fatty acid, mono- and triacylglycerol, wax ester, fatty alcohol, and several unidentified components. No complex lipids were detected. Isolated ECM exhibited polygalacturonase and laccase activity and was able to catalyze the hydrolysis of p-nitrophenyl butyrate, a model substrate for assessing cutinase activity. Cellulase, pectin lyase, and pectin methyl esterase activities were noted with both heated and unheated ECM preparations. Proteinase activity was not detected.

Journal Article↗
PubMed1971

Type-specific antigens of group B type Ic streptococci.

The type-specific antigens of group B type Ic (old designation type Ii) streptococci were extracted, purified, and characterized by serological and chemical methods. The Ia antigen, shared by types Ia and Ic, is a polysaccharide composed of 69% galactose and 25% glucosamine (i.e., 31% N-acetyl-glucosamine). However, these monosaccharides failed to inhibit significantly the quantitative precipitin reactions between purified antigen and type Ia antiserum. Indications are that the immunodominant group of this antigen consists of more than a simple monosaccharide. The Ic antigen, shared by types Ib and Ic, is a protein unrelated to the X and R protein antigens. Ic antigen consists of two serologically active determinants, one of which is susceptible to both trypsin and pepsin digestion and the other to pepsin but not to trypsin digestion. Acrylamide gel electrophoresis of the partially purified Ic antigen resulted in the occurrence of both determinants throughout the length of the gel, as shown by double gel diffusion slides.

Animals↗
PubMed1983

Immunobiological activities of synthetic lipid A analogs and related compounds as compared with those of bacterial lipopolysaccharide, re-glycolipid, lipid A, and muramyl dipeptide.

Thirteen acylated and phosphorylated derivatives of beta-1,6-linked glucosamine disaccharide (lipid A analogs), which were synthesized after the structural model of Salmonella-type lipid A, and seven similar derivatives of glucosamine monosaccharide (lipid A-related compounds) were studied for their immunobiological activities. These included mitogenicity and polyclonal B cell activation enhancement of migration of monocytes and polymorphonuclear leukocytes derived from human peripheral blood, stimulation of guinea pig peritoneal macrophages, activation of human complement, and stimulation of serum antibody production and induction of delayed-type hypersensitivity against ovalbumin in guinea pigs. Comparisons were made with lipid A, RE-glycolipid, lipopolysaccharide of natural sources, and a well-known synthetic adjuvant, N-acetylmuramyl-L-alanyl-D-isoglutamine. Some of the lipid A analogs were found to manifest the mitogenic, polyclonal B cell-activating macrophage-stimulating, complement-activating, and immunostimulating activities, although the observed activities were generally far less than those of natural products in intensity and efficiency. Other immunobiological effects exhibited by most of the synthetic lipid A analogs were the enhancement of migration of monocytes and polymorphonuclear leukocytes. It is premature to draw definite conclusions on structure-activity relationships, since a few compounds which were active in some assay systems were scarcely active in other assays. However, an indisputable fact was that beta-1,6-glucosamine disaccharide 1 alpha,4'-diphosphate, which carries two amide-bound (R)-3-hydroxytetradecanoyl and three ester-bound tetradecanoyl residues, and thus has the structure most closely resembling natural lipid A among test compounds in this study, was definitely active in all of the present assay systems. However, its potency was generally much less than natural products. Some of glucosamine monosaccharide derivatives, especially N-(R)-3-[(R)-3-hydroxytetradecanoyloxy]tetradecanoyl glucosamine, also exerted all of the in vitro activities described above. This fact suggests that a glucosamine disaccharide structure may not necessarily be a prerequisite as far as the in vitro immunobiological activities tested are concerned.

Acetylmuramyl-Alanyl-Isoglutamine↗
PubMed1988

Role of competition for nutrients in suppression of Clostridium difficile by the colonic microflora.

The cecal flora of mice is able to eliminate Clostridium difficile from the mouse cecum even when C. difficile is the first organism established. We used a continuous-flow (CF) culture model of the cecal flora to investigate the possibility that competition for nutrients is one mechanism for this antagonism. The medium for the CF cultures consisted of homogenates of fecal pellets from germfree mice. Carbohydrate analysis showed that mouse flora depleted 74 to 99.8% of the various carbohydrates from this environment-simulating medium. When inoculated into filtrates made from CF cultures of mouse flora, C. difficile multiplied slower than the dilution rate of the CF cultures unless glucose, N-acetylglucosamine, or N-acetylneuraminic acid was added. C. difficile did not synthesize hydrolytic enzymes able to cleave these monosaccharides from oligosaccharide side chains. As found previously, veal infusion broth did not support the growth of a microflora that could be transferred to gnotobiotic mice and fully suppress C. difficile. When mucin or monosaccharides found in mucin were added to veal infusion broth, the flora functioned normally in this regard. These data suggest that as yet unidentified organisms compete more efficiently than C. difficile for monomeric glucose, N-acetylglucosamine, and sialic acids found in colonic contents.

Amino Acids↗
PubMed1988

Identification of a galactose-binding lectin on Fusobacterium nucleatum FN-2.

A previous study has suggested that Fusobacterium nucleatum FN-2 contains a galactose-binding protein (lectin) on the cell surface (P. A. Murray, V. Matarese, C. I. Hoover, and J. R. Winkler, FEMS Microbiol. Lett. 40:123-127, 1987). In the present study, the molecular specificity and size of this lectin were investigated by several techniques. Whole-cell affinity chromatography with asialofetuin covalently coupled to Sepharose 6MB demonstrated that 81% of 3H-labeled F. nucleatum were specifically eluted by 0.5 M galactose. Specific binding was calcium dependent and did not occur in the presence of calcium chelators. Binding was inhibited by preincubation with galactose. Agglutination of human parotid saliva by F. nucleatum was also inhibited by galactose and its structural analogs. Inhibition by lactose was 2 times that of galactose, inhibition by p-aminophenyl galactosides was 4 times that of galactose, and inhibition by asialoglycopeptides was 100 times that of galactose. Similar inhibition results were obtained for hemagglutination of neuraminidase-treated erythrocytes. These findings suggest that the binding specificity of F. nucleatum FN-2 is more complex than simply the recognition of the monosaccharide galactose. This is consistent with the concept that lectins considered identical in terms of monosaccharide specificity can recognize fine differences in more complex structures. To identify the specific bacterial component(s) involved in galactose recognition, proteins of F. nucleatum FN-2 were separated on a 4 to 11% gradient sodium dodecyl sulfate slab gel, transferred to nitrocellulose paper to renature bacterial binding sites, and then incubated with 125I-labeled asialofetuin. Autoradiographs of the nitrocellulose revealed a band at a range of Mr 300,000 to 330,000 which was not present when the blots were preincubated with galactose. These data support the concept that F. nucleatum FN-2 possesses a lectin that recognizes galactose and galactose-containing substrates.

Asialoglycoproteins↗
PubMed1993

Immune response of rabbits to lipid A: influence of immunogen preparation and distribution of various lipid A specificities.

Sixty-two rabbit anti-lipid A serum samples were compared with respect to the immunogens used (synthetic lipid A and partial structures, natural lipid A, or acid-treated bacteria). Immunoglobulin (Ig) type-specific differences in rabbit response between liposomal membrane-embedded (LME) and other lipid A immunogens were found: LME lipid A elicited predominantly IgM antibodies. Previous findings of equally good immune responses to synthetic lipid A and acid-treated bacteria (L. Brade, E.T. Rietschel, S. Kusumoto, T. Shiba, and H. Brade, Infect. Immun. 51:110-114, 1986, and L. Brade, E.T. Rietschel, S. Kusumoto, T. Shiba, and H. Brade, Prog. Clin. Biol. Res. 231:75-97, 1987) turned out to be restricted to complement-fixing antibodies; IgG titers of sera against free lipid A (whether synthetic or natural) were significantly lower than those raised with bacteria. The results indicated an increase in IgG content of sera from LME lipid A over other free lipid A immunogens to acid-treated bacteria. These data underline the importance of the physicochemical environment for the immunogenicity of lipid A. As a second objective, the presence of various lipid A antibody specificities was tested with synthetic lipid A antigens. Antibodies to monophosphoryl lipid A were detected only in sera raised with monophosphoryl immunogens. Reactivity with monosaccharide partial structures of lipid A was found both in sera against monophosphoryl lipid A and in 60% of sera against bisphosphoryl lipid A. In the former, monosaccharide reactivity was of a magnitude similar to that of reactivity with lipid A; in sera against bisphosphoryl lipid A, it was lower. No reactivity or only marginal reactivity was found with phosphate-free lipid A, thus emphasizing the role of phosphate substitution for the lipid A epitopes recognized.

Animals↗
PubMed1993

Adhesion of Yersinia enterocolitica to purified rabbit and human intestinal mucin.

Interactions between Yersinia enterocolitica and purified intestinal mucins from rabbit and humans were investigated. Plasmid-bearing virulent organisms (but not plasmid-free nonvirulent bacteria) bound well to both mucins, suggesting that adherence was controlled by the virulence plasmid. Examination of binding to 14 different preparations of purified human intestinal mucin (8 preparations obtained from normal subjects and 6 samples from patients with cystic fibrosis) revealed no differences between normal and cystic fibrotic mucins in ability to serve as a binding substrate for virulent Y. enterocolitica. Analyses of binding curves suggested the presence of a single type of noninteracting receptor for Y. enterocolitica in both rabbit and human mucins with similar (but not necessarily identical) structures. Virulent bacteria bound to polystyrene through hydrophobic interactions that could be disrupted by treating the organisms with tetramethyl urea. In contrast, binding of plasmid-bearing Y. enterocolitica to intestinal mucin was not susceptible to tetramethyl urea and therefore does not appear to involve hydrophobic interactions. Prior incubation of organisms with mucin significantly inhibited binding to polystyrene, suggesting that mucin can mask hydrophobic adhesins on the bacterial surface. Hapten inhibition studies revealed that the monosaccharides galactose and N-acetylgalactosamine and the disaccharide lactose could markedly reduce (but not abolish) bacterial adherence to mucin but other monosaccharides and the RGD peptide had no effect on mucin binding. We conclude that virulent Y. enterocolitica is capable of interacting with the carbohydrate moiety of intestinal mucin. These interactions appear to be plasmid mediated and not hydrophobic.

Animals↗
PubMed1999

Variable carbohydrate modifications to the catalytic chains of the RgpA and RgpB proteases of Porphyromonas gingivalis W50.

Proteases of Porphyromonas gingivalis are considered to be important virulence determinants of this periodontal bacterium. Several biochemical isoforms of arginine-specific proteases are derived from rgpA and rgpB. HRgpA is a heterodimer composed of the catalytic alpha chain noncovalently associated with a beta adhesin chain derived from the C terminus of the initial full-length translation product. The catalytic alpha chain is also present as a monomer (RgpA) either free in solution or associated with membranes. rgpB lacks the coding region for the adhesin domain present in rgpA and yields only monomeric forms (RgpB) which again may be soluble or membrane associated. In this study, the catalytic chains of this unusual group of enzymes are shown to be differentially modified by the posttranslational addition of carbohydrate. A monoclonal antibody (MAb 1B5) raised to the monomeric RgpA did not react with the corresponding recombinant RgpA alpha chain expressed in Escherichia coli but was immunoreactive with P. gingivalis lipopolysaccharide. MAb 1B5 also reacted with the membrane-associated forms of RgpA and RgpB but not with the heterodimeric HRgpA and the soluble form of RgpB. RgpA treated with denaturants was capable of binding to MAb 1B5 whereas treatment with periodate abolished this binding, suggesting the presence of carbohydrate residues within the epitope. Chemical deglycosylation abolished immunoreactivity with MAb 1B5 and caused a approximately 30% reduction in the size of the membrane-associated enzymes. Monosaccharide analysis of HRgpA and RgpA demonstrated 2.1 and 14.4%, respectively, carbohydrate by weight of protein. Furthermore, distinct differences were detected in their monosaccharide compositions, indicating that these protease isoforms are modified not only to different extents but also with different sugars. The variable nature of these additions may have a significant effect on the structure, stability, and immune recognition of these protease glycoproteins.

Adhesins, Bacterial↗
PubMed1975

Isolation and characterization of the newly evolved ebg beta-galactosidase of Escherichia coli K-12.

The ebg beta-galactosidase of Escherichia coli K-12 strain LC110 has been purified and characterized. Strain LC110 is a Lac+ revertant of a mutant with a deletion of the lacZ beta-galactosidase gene. Its new ebg beta-galactosidase activity was shown to be due to a discrete protein, immunologically unrelated to lacZ beta-galactosidase. Its kinetics of action conformed to those of a simple conventional enzyme. With o-nitrophenyl-beta-D-galactoside as substrate, the Vmax was 11,200 nmol/min per mg of enzyme, the Km was 5 mM, and the activation energy was 12,400 cal/mol. Corresponding values for lacZ beta-galactosidase of wild-type E. coli K-12 were 350,000 nmol/min per mg of enzyme, 1.3 mM, and 8,000 cal/mol. A series of sugars has been examined as competitive inhibitors of ebg beta-galactosidase. Kinetic analyses suggest that ebg beta-galactosidase has a particularly high affinity for galactosamine and gamma-galactonolactone, binds galatose more tightly than lactose, and shows a general preference for monosaccharides rather than beta-galactosides. We conclude that the ebg beta-galactosidase may have arisen by modification of a gene involved with the metabolism of a monosaccharide, possibly a 2-amino sugar.

Antigens, Bacterial↗
PubMed1982

Utilization of chondroitin sulfate by Bacteroides thetaiotaomicron growing in carbohydrate-limited continuous culture.

When Bacteroides thetaiotaomicron, an obligate anaerobe from the human colonic flora, was grown in continuous culture with the mucopolysaccharide chondroitin sulfate as the limiting source of carbohydrate, growth yields ranged from 48 g of cell dry weight per mol of equivalent monosaccharide at a growth rate of 3.5 h per generation to 32 g per mol at a growth rate of 24 h per generation. The theoretical maximum growth yield (61 g of cell dry weight per mol of equivalent monosaccharide) was comparable to that of 54 g per mol, which was obtained previously when glucuronic acid, a component of chondroitin sulfate, was the limiting carbohydrate (S. F. Kotarski and A. A. Salyers, J. Bacteriol. 146:853-860, 1981). However, the maintenance coefficient was three times higher when chondroitin sulfate was the substrate than when glucuronic acid was the substrate. The specific activity of chondroitin lyase (EC 4.2.2.4), an enzyme which cleaves chondroitin sulfate into disaccharides, declined by nearly 50% as growth rates decreased from 3.5 to 24 h per generation. By contrast, the specific activities of several glycolytic enzymes and disaccharidases remained constant over this range of growth rates. Although chondroitin sulfate was growth limiting, some carbohydrate was detectable in the extracellular fluid at all growth rates. At rapid growth rates (1 to 2 h per generation), this residual carbohydrate included fragments of chondroitin sulfate having a wide range of molecular weights. At slower growth rates (2 to 24 h per generation), the residual carbohydrate consisted mainly of a small fragment which migrated on paper chromatograms more slowly than the disaccharides produced by chondroitin lyase but faster than a tetrasaccharide. This small fragment may represent the reducing end of the chondroitin sulfate molecule.

Bacteroides↗
PubMed1992

Functional roles assigned to the periplasmic, linker, and receiver domains of the Agrobacterium tumefaciens VirA protein.

VirA and VirG activate the Agrobacterium tumefaciens vir regulon in response to phenolic compounds, monosaccharides, and acidity released from plant wound sites. VirA contains an amino-terminal periplasmic domain and three cytoplasmic domains: a linker, a protein kinase, and a phosphoryl receiver. We constructed internal deletions of virA that truncate one or more domains and tested the ability of the resulting proteins to mediate environmentally responsive vir gene activation in vivo. The periplasmic domain is required for sensing of monosaccharides (in agreement with earlier results), while the linker domain is required for sensing of phenolic compounds and acidity. The phosphoryl receiver domain of VirA plays an inhibitory role in signal transduction that may be modulated by phosphorylation. The carboxy terminus of the protein was also dispensable for tumorigenesis, while the periplasmic domain was required.

Agrobacterium tumefaciens↗
PubMed2005

Environmental pH sensing: resolving the VirA/VirG two-component system inputs for Agrobacterium pathogenesis.

Agrobacterium tumefaciens stands as one of biotechnology's greatest successes, with all plant genetic engineering building on the strategies of this pathogen. By integrating responses to external pHs, phenols, and monosaccharides, this organism mobilizes oncogenic elements to efficiently transform most dicotyledonous plants. We now show that the complex signaling network used to regulate lateral gene transfer can be resolved as individual signaling modules. While pH and sugar perception are coupled through a common pathway, requiring both low pH and sugar for maximal virulence gene expression, various VirA and ChvE alleles can decouple pH and monosaccharide perception. This VirA and ChvE system may represent a common mechanism that underpins external pH perception in prokaryotes, and the use of these simple genetic elements may now be extended to research on specific responses to changes in environmental pH.

Agrobacterium tumefaciens↗
PubMed1969

Influence of O side chains on the attachment of the Felix O-1 bacteriophage to Salmonella bacteria.

The adsorption rate constant (ARC) of the Felix O-1 (FO) bacteriophage to sensitive Salmonella strains was used to determine the effect of variations in surface antigens on phage attachment. The N-acetylglucosamine of the common-core polysaccharide of the Salmonella lipopolysaccharide (LPS) was found to be an essential part of the receptor for the FO phage in conformation with earlier reports. It was found that (i) the ARC was low for strains having O side chains containing two or three non core monosaccharides, (ii) the ARC varied when the O side chain contained no, or only one, noncore monosaccharide, (iii) the ARC was high when the O side chain contained only one repeating unit, and (iv) the ARC was high to mutants of chemotype Ra in which the N-acetylglucosamine was the terminal sugar of the LPS. Since a good correlation was found between the ARC of the FO phage and the phage-inactivating capacity of phenol water-extracted LPS, the results suggest that only the structure and composition of the LPS determines the adsorption rate of the FO phage. The phage-inactivating capacity of LPS from the Ra mutants increased in parallel with higher glucosamine contents in the core polysaccharide. In smooth strains having long and numerous O side chains, the access of the FO phage to its receptor is probably blocked by the presence of the side chains, whereas short and numerous side chains or T1 side chains do not interfere with the FO attachment.

Antigens↗
PubMed1991

43-kilodalton glycoprotein from Paracoccidioides brasiliensis: immunochemical reactions with sera from patients with paracoccidioidomycosis, histoplasmosis, or Jorge Lobo's disease.

Sera from patients with paracoccidioidomycosis (PCM), histoplasmosis (HP), or Jorge Lobo's disease (JL) were titrated against purified gp43 from Paracoccidioides brasiliensis by using both enzyme-linked immunosorbent assay (ELISA) and immunoprecipitation (IPP) reactions with 125I-labeled antigens. In IPP, PCM sera and other sera could be distinguished on the basis of serum titers, whereas in ELISA, 53% of the HP sera and 29% of the JL sera reacted similarly to the PCM sera. To investigate the possible role of the carbohydrate epitopes in these reactions, we compared the reactivities of sera from several patients with native and deglycosylated gp43. Competition experiments were carried out with monosaccharides as inhibitors. The results suggest that greater than 85% of the reactions of the PCM sera with gp43 involved peptide epitopes. Cross-reactions with HP and JL sera in ELISA were predominantly attributed to periodate-sensitive carbohydrate epitopes containing galactosyl residues. HP and JL sera which reacted strongly with gp43 in ELISA were only weakly reactive or did not react in IPP with labeled antigens in solution. Moreover, ELISA reactions could be significantly inhibited either by monosaccharides or by periodate treatment. Apparently, carbohydrate epitopes in gp43 are more accessible to the antibodies when the molecule is bound to a plastic substrate than when it is in solution. Structural changes in the gp43 antigen arising by N deglycosylation abolish reactivity with PCM sera and support the existence of conformational peptide epitopes.

Blastomycosis↗
PubMed2004

Selective decrease in paracellular conductance of tight junctions: role of the first extracellular domain of claudin-5.

Claudin-5 is a protein component of many endothelial tight junctions, including those at the blood-brain barrier, a barrier that limits molecular exchanges between the central nervous system and the circulatory system. To test the contribution of claudin-5 to this barrier function of tight junctions, we expressed murine claudin-5 in Madin-Darby canine kidney II cells. The result was a fivefold increase in transepithelial resistance in claudin-5 transductants and a reduction in conductance of monovalent cations. However, the paracellular flux of neither neutral nor charged monosaccharides was significantly changed in claudin-5 transductants compared to controls. Therefore, expression of claudin-5 selectively decreased the permeability to ions. Additionally, site-directed mutations of particular amino acid residues in the first extracellular domain of claudin-5 altered the properties of the tight junctions formed in response to claudin-5 expression. In particular, the conserved cysteines were crucial: mutation of either cysteine abolishted the ability of claudin-5 to increase transepithelial resistance, and mutation of Cys(64) strikingly increased the paracellular flux of monosaccharides. These new insights into the functions of claudin-5 at the molecular level in tight junctions may account for some aspects of the blood-brain barrier's selective permeability.

Amino Acid Sequence↗
PubMed1995

Fluid intake and industrial processing in apple juice induced chronic non-specific diarrhoea.

Dietary factors have been shown to contribute to the occurrence or persistence of chronic non-specific diarrhoea (CNSD). Among these are low dietary fat, high fluid consumption, and the consumption of apple juice. Prompted by the clinical impression that freshly pressed and unprocessed ('cloudy') apple juice was less likely to induce diarrhoea than normal, enzymatically processed ('clear') apple juice, both juices were compared in terms of carbohydrate malabsorption, gastric emptying, and effects on defecation patterns. Clear and cloudy apple juice differ in their fibre and non-absorbable monosaccharide and oligosaccharide contents. Ten healthy children aged 3.6 to 5.9 years ingested 10 ml/kg of clear and cloudy apple juice; in five of them it was enriched with 40 mg of [1-13C]-glycine. Clear apple juice resulted in increased (> or = 20 ppm) breath hydrogen excretion in 8/10, compared with 5/10 after cloudy apple juice; peak breath hydrogen was higher in the clear apple juice group (35 (4) and 18 (3) ppm, respectively). Gastric emptying as determined by means of labelled breath carbon dioxide (13CO2) excretion was similar with both juices. In a four week crossover clinical trial 12 children, formerly diagnosed as having CNSD, were given extra clear fluids (excluding fruit juices; > or = 50% over basal consumption), clear apple juice, or cloudy apple juice, for five day periods. Extra fluids and cloudy apple juice did not influence stool frequency and consistency compared with the basal period. In contrast, clear apple juice significantly promoted diarrhoea. It is suggested that, in addition to fructose, the increased availability of non-absorbable monosaccharides and oligosaccharides as a result of the enzymatic processing of apple pulp is an important aetiological factor in apple juice induced CNSD.

Breath Tests↗
PubMed1990

Dietary factors and the risk of developing insulin dependent diabetes in childhood.

OBJECTIVE: To study different nutrients and food additives as risk factors for insulin dependent diabetes mellitus in childhood. DESIGN: Prospective case-control study. Parents of the children being studied were asked to fill in a questionnaire regarding the children's frequency of consumption of various foods. Parents of children with diabetes were asked about the period before onset of the disease. SETTING: Population based study throughout Sweden. SUBJECTS: 339 Children aged 0-14 who had recently developed insulin dependent diabetes mellitus and 528 control children matched for age, sex, and county of residence who were traced through the official Swedish population register. MAIN OUTCOME MEASURES: Foods were classified according to their content of protein, fat, carbohydrates, monosaccharides or disaccharides, nitrosamines, nitrates or nitrites, vitamin C, and fibres. The frequency of intake was categorised as high, medium, and low and the relative risk for developing insulin dependent diabetes was estimated for the three frequencies of intake and calculated as odds ratios. RESULTS: Significant linear trends for dose response in odds ratios by frequency of intake were shown for solid foods containing high amounts of protein (odds ratio for low frequency of intake 1.0; medium 2.3; and high 5.5), and nitrosamines (1.0; 1.7; 2.6) and significant but non-linear trends were found for carbohydrates (1.0; 1.3; 4.4) and nitrates or nitrites (1.0; 0.8; 2.4). The significant trends were not affected when the results were standardised for possible confounders. No significant increases in odds ratios were found for protein, monosaccharides and disaccharides, vitamin C, and fibres. CONCLUSION: Nutrients and food additives such as protein, carbohydrate, and nitrosamine compounds may influence the risk of developing insulin dependent diabetes in childhood and significant trends in odds ratios indicate a causal relation.

Ascorbic Acid↗