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Effect of fermentation on lactose, glucose, and galactose content in milk and suitability of fermented milk products for lactose intolerant individuals.

The lactose, glucose, and galactose content in various fermented milk products was studied by enzymatic methods. Lactose was decreased in all fermented products. After 11 days storage of yogurt the lactose content decreased to about 2.3 g/100 compared to 4.8 g/100 g in nonfermented milk. During the same period, galactose content increased from traces in milk to 1.3 g/100 g in yogurt. Results were similar with acidophilus and bifidus milk. Buttermilk, kefir, and ropy milk showed 26, 30, and 20% decreases in lactose content. Eight lactose intolerant individuals showed symptoms of abdominal distress and diarrhea following consumption of 500 ml of low fat milk whereas ingestion of the same quantity of yogurt or acidophilus milk did not result in any symptoms. Fermented milk products should be considered in formulating diets for lactose-intolerant subjects.

Adolescent↗

Intestinal absorption of D-galactose and L-leucine and intestinal disaccharidase activities in growing chickens fed different raw legume diets.

A significant (P less than .01) impairment in the rate of growth, along with a significant (P less than .01) inhibition in the rate of in vivo intestinal absorption of D-galactose and L-leucine, and in the in vitro intestinal absorption of D-galactose, was found in growing chickens fed ad libitum over a 60-day period, diets containing the raw legumes Vicia faba, Glycine soja, Vicia ervilia, and Phaseolus vulgaris as the main source of protein. Furthermore, a significant (P less than .01) reduction in the intestinal disaccharidase activity was found in the legume-fed chickens. The possible nature of these effects was discussed.

Animal Feed↗

NAD(H) recycling activity of an engineered bifunctional enzyme galactose dehydrogenase/lactate dehydrogenase.

A chimeric bifunctional enzyme composing of galactose dehydrogenase (galDH; from Pseudomonas fluorescens) and lactate dehydrogenase (LDH; from Bacillus stearothermophilus) was successfully constructed. The chimeric galDH/LDH possessed dual characteristics of both galactose dehydrogenase and lactate dehydrogenase activities while exhibiting hexameric rearrangement with a molecular weight of approximately 400 kDa. In vitro observations showed that the chimeric enzyme was able to recycle NAD with a continuous production of lactate without any externally added NADH. Two fold higher recycling rate (0.3 mM/h) than that of the native enzyme was observed at pH values above 8.5. Proximity effects became especially pronounced during the recycling assay when diffusion hindrance was induced by polyethylene glycol. All these findings open up a high feasibility to apply the NAD(H) recycling system for metabolic engineering purposes e.g. as a model to gain a better understanding on the molecular proximity process and as the routes for synthesizing of numerous high-value-added compounds.

Bacterial Proteins↗

[Changes in lipid-carbohydrate metabolism of rabbits after long-term administration of lactose and its derivatives--glucose and galactose].

Rabbits were administered with lactose, glucose or galactose (3 g per kg of body weight) within three months, after which an alteration in the pattern of response to a sugar loading was noted. Content of cholesterol was distinctly increased in blood serum after administration of glucose. After administration of lactose the increase in content of cholesterol was less distinct. Cholesterol, kephalin and lecithin were markedly deposited in heart and liver after the carbohydrates administration. On the treatment with galactose the total content of lipids and triglycerides was increased in heart. If animals were loaded with lactose, content of triglycerides was increased in heart only.

Animals↗

[Glucose-galactose malabsorption. The first reported case in Denmark].

The first diagnosed case of glucose-galactose malabsorption (GGM) in Denmark is presented. GGM is an autosomal recessive disorder characterized by neonatal début of severe osmotic diarrhoea. Untreated, GGM is potentially fatal. The disease is chronic and caused by a defect in the Na+/glucose co-transporter, SGLT1, located on the jejunal brush border. Diagnosis is based upon oral glucose tolerance test, stool reducing substances, and may be substantiated by genetic analysis. Treatment consists in eliminating alimentary glucose and galactose. Nurtured on this diet the patient will develop normally.

Diagnosis, Differential↗

Effect of sodium, mannitol, and magnesium on glucose, galactose, 3-O-methylglucose, and fructose absorption in the human ileum.

Although it is generally agreed that active sugar absorption in vitro is absolutely dependent on the presence of sodium ions on the luminal side of the mucosa, previous in vivo studies in the ileum of rat, dog and man have shown that active glucose absorption is almost as rapid from a sodium-free mannitol solution as from a sodium chloride solution. These experiments were performed in hopes of reconciling this discreptancy. Absorption of three actively transported sugars (glucose, galactose, and 3-O-methylglucose) having different apparent Km's, and of fructose (absorbed by a separate carrier-mediated process) were measured in the human ileum in vivo. The following observations were made: (1) Mannitol substitution for sodium results in only a slight reduction (23%) in the active absorption of glucose. (2) Magnesium substitution for sodium results in a greater depression (45%) of glucose absorption. (3) The apparent Km for glucose absorption is increased when sodium is replaced by magnesium, but the Vmax is not altered. (4) Magnesium does not depress glucose absorption or the apparent Km for glucose transport when sodium is present in the perfusing solution. (5) Neither sodium removal nor magnesium has any effect on fructose absorption. (6) Absorption of galactose and 3-O-methylglucose (low affinity sugars for the glucose carrier) is reduced by about 40 to 50% when mannitol replaces sodium, but magnesium substitution for mannitol in a sodium-free medium does not further depress absorption of these sugars. The following conclusions are suggested by these results: First, part of the discrepancy between previous in vitro and in vivo experiments was due to the type of test sugar (glucose versus glucose analogue) and the solute used to replace sodium in the luminal solution. Second, magnesium is more effective than mannitol in reducing sodium concentration at the glucose transport site on the brush border. Third, luminal sodium ions have an important effect on active sugar absorption in the human small intestine in vivo, as they do in vitro. And, fourth, there is a component of active sugar absorption (about one-half) which appears to be independent of luminal sodium ions in vivo.

Adult↗

[Biochemical and clinical findings in congenital abnormalities of galactose metabolism (author's transl)].

Current knowledge of the biochemical basis of abnormalities in galactose metabolism are discussed. The clinical picture, analysis of frequency and therapy are described. Although the galactokinase defect hat been described only rarely, abundant literature has been published on the Gal-1-PUT defect. Five variations of this defect are known (Duarte, Los Angeles, Rennes, Indiana and Negro variants), but these simulate only partially the clinical picture of galactosaemia. The UDP-Gal-4-epimerase defect has only once been described. Defects in galactose metabolism which show autosomal recessive inheritance are demonstrated in milk-fed infants by means of the Guthrie test. If the clinical picture arouses the suspicion of a defect in Gal-1-PUT or galactokinase, then a milk-free diet should be given until the diagnosis has been verified by enzyme analysis. Children who have been fed on a lactose-free diet show normal physical and mental development. If possible the entire family of the proband should undergo enzyme analysis in order to detect and to counsel all the heterozygotes in the family. Genetic counselling is considered to be absolutely indicated in this case. Termination of pregnancy is not indicated under any circumstances.

Adenosine Triphosphate↗

Usefulness of galactose oxidase-Schiff test in rectal mucus for screening of colorectal malignancy.

Based on a "field-effect" theory in colon carcinogenesis, and the expression of the disaccharide tumor marker D galactose-beta-[1-->3]-N-acetyl-D-galactosamine (Gal-GalNAc) in the rectal mucus of patients with cancer and precancer of the colon, Shamsuddin developed a simple, accurate, inexpensive, easy to perform and rapid (< or = 15 min) screening test for colonic cancer and precancerous lesions. In this study we examined 137 rectal mucus samples of randomly selected patients with colorectal malignancy or other colorectal diseases to confirm the sensitivity and specificity of this test in Croatia. Additionally, to test the validity of the "field-effect" theory, that the mucosa away from the obvious cancer will show abnormalities as a result of the generalized effect of the carcinogen throughout the entire field of the target tissue, we also monitored a subset of 53 patients post-operatively. Individuals free of colonic or any other malignancies served as control (n = 31). The rectal mucin was smeared on membrane filter and developed by a sequential reaction of galactose oxidase (GO) and Schiff's reagent. The test results were correlated to the findings from colonoscopy/surgery and histopathology. The sensitivity of the test was shown to be 100% and the specificity was 96.8% (p < 0.001). Interestingly, the test was positive in 60% (32 of 53) of the samples collected from patients after tumor resection, showing the persistence of the biochemical changes even though malignant tumors were removed, hence supporting the field-effect phenomenon of carcinogenic stimuli. Five patients out of these 32 (16%) postoperative cases with positive GO test had a tumor recurrence within a year (0.05 < p < 0.10), suggesting that a persistently positive GO test in this population may serve as a predictor of tumor recurrence. We conclude that Gal-GalNAc is an early and intermediate biomarker, suitable not only for the detection of malignancy in its inception, but also for monitoring of people at high risk for cancer, and the efficacy of the cancer therapy as well as secondary prevention by this technology.

Colonic Polyps↗

In vitro targeted killing of human endothelial cells by co-incubation of human serum and NGR peptide conjugated human albumin protein bearing alpha (1-3) galactose epitopes.

The NGR/alpha1,3Gal-HSA peptide was designed to specifically target CD13 positive cells and induce cell lysis. NGR is the targeting component of the peptide in that it binds the CD13 isoform (aminopeptidase) that is expressed in tumor vessels. Galactose alpha1,3-galactose terminal carbohydrate epitope (alpha1,3Gal) induces a strong antibody reaction in human and Old World Monkeys and in vivo, this reaction leads to organ rejection. The human serum albumin (HSA) bearing alpha1,3Gal epitope was therefore used to lyse cells. In the present study, we were able to demonstrate that NGR/alpha1,3Gal-HSA binds CD13 positive human umbilical vein endothelial cells (HUVEC). We also found by live/dead fluorescent staining that NGR/alpha1,3Gal-HSA was able to induce lysis of HUVECs upon incubation with human serum. Therefore, by conjugating NGR to HSA bearing alpha1,3Gal epitopes, we are able to specifically target and lyse cells expressing CD13. This strategy may be potentially useful in tumor anti-angiogenesis therapy.

Angiogenesis Inhibitors↗

[1H-NMR study on protein of normal and galactose cataractous rat whole lenses].

The non-invasive method of 1H-nuclear magnetic resonance (1H-NMR) spectroscopy was applied to rat whole lens. The alterations of aging and experimentally induced cataract on protein structures in rat lenses were examined by comparing high resolution 1H-NMR spectra. 1H-NMR measurements were carried out using the water suppression method and resolution enhancement method. The 1H-NMR spectra of normal lens showed narrow resonance lines of lactate and broad ones of aliphatic amino acid residues of lens protein. There was no remarkable change in the spectral pattern of normal lenses within one week. There was also no effect of aging on the spectral pattern of normal lenses. On the other hand the lines due to the aliphatic amino acid residues of the galactose cataractous lens protein were narrower than those of normal lens. This finding suggests that the increase of mobilities of the residues caused by galactose cataract is reflected by the spectral pattern.

Animals↗

Mutational analysis of the galactose binding ability of recombinant ricin B chain.

Ricin B chain (RTB) is an N-glycosylated galactose-specific lectin which folds into two globular domains. Each domain binds one galactoside. The x-ray crystallographic structure has shown that the two binding sites are structurally similar and contain key binding residues which hydrogen bond to the sugar, and a conserved tripeptide, Asp-Val-Arg. We have used oligonucleotide site-directed mutagenesis to change either the binding residues or the homologous tripeptide in one or other or in both of the sites. The 5' signal sequence and RTB coding region were excised from preproricin cDNA and fused in frame to generate preRTB cDNA. Transcripts synthesized in vitro from wild-type or mutant preRTB cloned into the Xenopus transcription vector pSP64T using SP6 RNA polymerase, were microinjected into Xenopus oocytes. The recombinant products were segregated into the oocyte rough endoplasmic reticulum and core-glycosylated, and the N-terminal signal peptide was removed. Mutating sugar binding sites individually did not abrogate the lectin activity of RTB. When both sites were changed simultaneously, RTB was produced which was soluble and stable but no longer able to bind galactose. Changing the Asn residues of the two RTB N-glycosylation sites to Gln showed that oligosaccharide side chains were essential for both the stability and biological activity of recombinant RTB.

Animals↗

[Relation between metabolic and histological changes in the rat lens during the pathogenesis of galactose cataract].

A comparative study of the metabolic kinetics of organophosphate compounds, biochemical changes and histological changes, in the rat lens during the process of the generating galactose cataract. The change of alpha-glycerophosphate (alpha-GP) with time was analogous to that of dulcitol and the decrease of alpha-GP depended on histological destruction. Furthermore phosphorylcholine decreased considerably before adenosine triphosphate (ATP) decreased, the latter commencing when the histological destruction of the lens progressed to all around the lens. In addition, inositol decreased rapidly after ingestion of galactose. It was concluded that the decrease of alpha-GP was caused by the flow from the lens, and the decrease of ATP started from the epithelium in the lens. Therefore, it was speculated that the decrease of inositol was caused by decrease in the active transport of inositol.

Animals↗

Inhibition and inactivation of bovine mammary and liver UDP-galactose-4-epimerases.

Bovine liver and mammary UDP-galactose-4-epimerases were investigated with respect to various inhibitors and inactivators. Uridine nucleotides and NADH are potent inhibitors with Ki values in the low micromolar range. The NAD+/NADH ratio may be an important physiological control mechanism for it affects markedly the activity of the enzyme with 50% inhibition occurring at a ratio of 20:1. In the presence of uridine nucleotides binding of NADH to the epimerases is enhanced. Consequently, the effect of changes in the NAD+/NADH ratio in vivo would not be immediately apparent as uridine nucleotides would slow down the displacement of NADH by NAD+. Neither uridine nor galactose 1-phosphate inhibits the purified enzymes as previously reported with the impure liver enzyme. Uridine nucleotides provide almost total protection against the apparent first order inactivation of the epimerases by trypsin and allow determination of dissociation constants. NAD+ partially protects against trypsin inactivation. Inactivation with various sulfhydryl reagents is complex and the results indicate that at least three sulfhydryl groups may be modified before total inactivation occurs. Partial inactivation occurs upon modification of the epimerases with 2-hydroxy-5-nitrogenzyl bromide. Some protection against this modification is provided by the combination of NAD+ and UDP.

Animals↗

Elemental distribution in frozen-hydrated rat lenses with galactose cataract.

The elemental distributions in frozen-hydrated rat lenses with galactose cataract were compared before and after the onset of the nuclear cataract to investigate the possible role of ion levels in the lens opacification due to the phase separation of the lens cytoplasm. The maps of the weight concentrations of the minor elements, S, Cl, K and Ca, on the basis of wet weight in the central plane of lens were obtained by X-ray analysis with the high energy ion microprobe at a resolution of 50 microns. Before the onset of the nuclear cataract, the distributions of Cl and K, were almost normal, except in the lens posterior periphery with high Cl and low K. In the lens with the nuclear opacity, sudden changes were observed. The Cl increased throughout the lens, and K decreased throughout the lens except at lens anterior thin layer. However, the totalized monovalent ion level changed only slightly. The Ca level increased throughout the lens after the onset of the nuclear cataract, suggesting a possible role of Ca in the nuclear opacification of galactose cataract of rats. The distributions of S were similar to the protein density distributions previously known both in the normal and in the cataractous lenses.

Animals↗

[Identification of inborn errors of galactose metabolism in patients with cataracts].

133 patients with congenital or idiopathic cataracts were studied (94 patients had ages between 1 month and 14 years; 10 patients had ages between 16 and 50 years and 29 patients did not have an age registry) along with 18 patients with a clinical diagnosis of classic galactosemia. The activity of galactokinase (GALAK) and that of erythrocyte galactose-1-phosphate uridyl transferase (GALT) was measured. There were no individuals with a total deficiency of GALK or GALT. The cataract patients of ages between 1 monthly and 14 years, 3 (3.19%) and 4 (4.25%) showed GALK and GALT levels in the range corresponding to the respective heterozygotes. As compared with the expected incidence of heterozygotes in the general population (0.2% for GALK and 0.8% for GALT) we found a significant rise of individuals with low levels of enzymes for the metabolism of galactose. The possibility that heterozygote galactosemic states contribute a risk factor in the development of cataracts and its therapeutic implications are discussed.

Adolescent↗

A calcium-dependent galactose-binding lectin from the tunicate Polyandrocarpa misakiensis. Isolation, characterization, and amino acid sequence.

A lectin was isolated from the homogenate of the tunicate Polyandrocarpa misakiensis by heat treatment, ammonium sulfate fractionation, gel filtration, and high-performance ion-exchange chromatography. Analytical gel filtration on Superose 12 and sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the lectin is a monomeric protein with a molecular mass of approximately 15 kDa. The lectin bound to an immobilized D-galactose column in the presence of calcium ion with a threshold of 500 microM and eluted completely with 5 mM EDTA. It did not bind to an immobilized D-mannose or N-acetyl-D-galactosamine column. Thus, Polyandrocarpa lectin was found to be a calcium-dependent galactose-binding lectin. The complete amino acid sequence of Polyandrocarpa lectin was determined by automated or manual Edman sequencing of the peptides derived by digestion with trypsin, endoproteinase Asp-N, Staphylococcus aureus V8 protease, and pepsin. It is composed of 125 residues, contains no carbohydrate group, and has a calculated molecular mass of 14,034 Da. The lectin contains four half-cystines, and Cys-21 and Cys-119 and also Cys-96 and Cys-111 form intrachain disulfide bridges, respectively. The amino acid sequence of Polyandrocarpa lectin shows about 20-30% homology with those of fly, barnacle, sea urchin, and several vertebrate lectins that belong to C-type lectin (Drickamer, K. (1988) J. Biol. Chem. 263, 9557-9560). Although the physiological role of Polyandrocarpa lectin is not clear, preliminary experiments suggest that the lectin may be related to defense mechanisms because it has a strong antibacterial activity.

Amino Acid Sequence↗

[Hereditary abnormalities of galactose metabolism: diagnosis and biochemical supervision (author's transl)].

The authors define the main stages of the biochemical study of hereditary abnormalities of galactose metabolism. They review laboratory examinations for detection, enzyme examinations which provide the diagnostic proof, further examinations which permit one to follow the course and efficacy of a galactose-free diet, the demonstration of genetic variants, the technics of antenatal diagnosis and routine neonatal detection.

Biological Assay↗

Effects of galactose depletion from oligosaccharide chains on immunological activities of human IgG.

We previously reported a decrease in the content of galactose residues in oligosaccharide chains of serum IgG from patients with rheumatoid arthritis, which was presumed to affect the 3 dimensional structure of CH2 domain. In the present study, we prepared the galactose depleted IgG (agalacto IgG) and characterized its immunological activities. Significant reduction in Clq binding and Fc receptor binding was observed in agalacto IgG. However, IgM rheumatoid factor binding and protein A binding were the same as with intact IgG. Our results implied the biological function of the carbohydrate moiety of human IgG.

Arthritis, Rheumatoid↗