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PubMed1985

Digestion and absorption rates of lactose, glucose, galactose, and fructose in three infants with congenital glucose-galactose malabsorption: perfusion studies.

The digestion rates of lactose and the absorption rates of glucose, galactose, and fructose were studied by continuous perfusion of the jejunum in three patients aged 7 weeks to 9 months with congenital glucose-galactose malabsorption (infusion rate:1.0 ml min-1; concentration of each sugar: 200 mM; perfusion distance: 30 cm). The mean absorption rates of glucose and galactose were 26.5 and 43.8 mumol min-1 30 cm-1, respectively, and were significantly reduced (p less than 0.001) to 13 and 22%, respectively, of intake. On the other hand, the absorption of fructose was 133.3 mumol min-1 30 cm-1, i.e., as high as in the controls. The hydrolysis rate of lactose was also normal (134.0 mumol min-1 30 cm-1). However, the absorption rates of glucose and galactose released from the disaccharide were as low as the perfusion of free monosaccharides. In patients with glucose-galactose malabsorption the glucose absorption rate is as low as that of galactose. No additional glucose transport system seems to exist. A hydrolase related transport system is also of no importance in compensating for the primary defect of monosaccharide absorption.

Biological Transport, Active↗
PubMed1991

Clinical trial of home available, mixed diets versus a lactose-free, soy-protein formula for the dietary management of acute childhood diarrhea.

A randomized clinical trial was completed to study the severity, duration, and nutritional outcome of acute diarrhea in 85 Peruvian children between 5 and 24 months of age who received a soy-protein-isolate, lactose-free formula (group SF) or one of two mixtures of home-available foods, all in amounts up to 110 kcal/kg of body weight/day. The mixed diets contained either wheat flour, pea flour, carrot flour, sucrose, and vegetable oil (group WP) or potato flour, dried whole milk, carrot flour, sucrose, and oil (group PM). The characteristics of the children in each group were generally similar initially. There were no differences in treatment failure rate by diet group. Fecal outputs were similar in all groups during the first day of treatment, averaging 60 to 65 g/kg/day. However, stool outputs were greater for the PM group than for other groups on days 3 and 4, and were less for the SF group than the other groups on days 5 and 6. The estimated median durations of diarrhea in the WP group (52 h) and PM group (53 h) were significantly less than in the SF group (154 h, p = 0.005). Energy intakes, energy absorption, and nitrogen retention (% of intake) were generally similar in all dietary groups, although there were minor differences in the absorption of specific macronutrients. Children in all groups gained weight during hospitalization, and there were no significant differences by diet group in the change in anthropometric status during treatment. We conclude that these locally available, low-cost staple food mixtures offer a safe and nutritionally adequate alternative to a commercially produced lactose-free formula for the dietary management of young children with acute diarrhea in this setting.

Acute Disease↗
PubMed1998

Flavobacterium hibernum sp. nov., a lactose-utilizing bacterium from a freshwater Antarctic lake.

Four freshwater Antarctic lakes were examined for the presence of beta-galactosidase-producing bacteria using mineral medium enrichments and lactose. Enrichments from only one of the lakes produced growth and two strains were isolated that were very similar in phenotype and fatty acid profile, and shared considerable homology in their DNA (DNA-DNA hybridization = 93 +/- 7%). The strains were psychrotrophic with theoretical Tmax, Tmin and Topt of 30-31, -7 degrees and 26 degrees C, respectively. The beta-galactosidase in cell extracts had an optimal activity at 39 degrees C. The strains were Gram-negative rods, showed gliding motility, contained branched and hydroxy fatty acids, and menaquinone 6 as the major respiratory quinone. The strains did not form microcysts and utilized lactose while using ammonium ions as a source of nitrogen, and a range of other sugars. The G + C content of the DNA was 34 mol%. Phylogenetic analysis of one of the strains, by comparison of 16S rDNA sequences, showed that it was most similar, but not identical to, Flavobacterium columnare and '[Sporocytophaga] cauliformis'. Both species could be differentiated phenotypically from the Antarctic isolates. DNA-DNA hybridization of the Antarctic isolate with six different members of the Flavobacterium 16S rDNA cluster showed no strain with greater than 18% relatedness. The nearest type species to the Antarctic isolate in the phylogenetic analysis was Flavobacterium aquatile. The name Flavobacterium hibernum is proposed for the Antarctic strains, and the type strain is ATCC 51468T (= ACAM 376T).

Antarctic Regions↗
PubMed1987

Uptake of galactose and lactose by Kluyveromyces lactis: biochemical characteristics and attempted genetical analysis.

Study of the lactose and galactose transport systems in Kluyveromyces lactis has shown that lactose uptake is by active transport. The transport system is under monogenic control and is inducible. Galactose uptake is also by active transport but the system is controlled by two genes which, in the four strains we studied, are present only in K. lactis CBS 2359. Galactose uptake in the other K. lactis strains is by a simple diffusion process.

Biological Transport↗
PubMed2001

The combination of molecular dynamics with crystallography for elucidating protein-ligand interactions: a case study involving peanut lectin complexes with T-antigen and lactose.

Peanut lectin binds T-antigen [Galbeta(1-3)GalNAc] with an order of magnitude higher affinity than it binds the disaccharide lactose. The crystal structures of the two complexes indicate that the higher affinity for T-antigen is generated by two water bridges involving the acetamido group. Fresh calorimetric measurements on the two complexes have been carried out in the temperature range 280-313 K. Four sets of nanosecond molecular-dynamics (MD) simulations, two at 293 K and the other two at 313 K, were performed on each of the two complexes. At each temperature, two somewhat different protocols were used to hydrate the complex in the two runs. Two MD runs under slightly different conditions for each complex served to assess the reliability of the approach for exploring protein-ligand interactions. Enthalpies based on static calculations and on MD simulations favour complexation involving T-antigen. The simulations also brought to light ensembles of direct and water-mediated protein-sugar interactions in both the cases. These ensembles provide a qualitative explanation for the temperature dependence of the thermodynamic parameters of peanut lectin-T-antigen interaction and for the results of one of the two mutational studies on the lectin. They also support the earlier conclusion that the increased affinity of peanut lectin for T-antigen compared with that for lactose is primarily caused by additional water bridges involving the acetamido group. The calculations provide a rationale for the observed sugar-binding affinity of one of the two available mutants. Detailed examination of the calculations point to the need for exercising caution in interpreting results of MD simulations: while long simulations are not possible owing to computational reasons, it is desirable to carry out several short simulations with somewhat different initial conditions.

Anti-Bacterial Agents↗
PubMed1995

Determination of the minimum dose of lactose drug carrier that can be sensed during inhalation.

Lactose is commonly used as a carrier for inhaled drugs. Twenty healthy volunteers without respiratory symptoms inhaled seven different doses of lactose and a placebo (empty) dose through the four place Diskhaler device, in order to determine the lowest dose that could be reliably sensed. The minimum dose for which all subjects reported taste or feel sensations was 10 mg. This has implications regarding the amount of carrier used in future drug delivery systems.

Administration, Inhalation↗
PubMed1984

The effect of yoghurt on some components of the gut microflora and on the metabolism of lactose in the rat.

Feeding yoghurt or base milk (from which the yoghurt was prepared by fermentation) to rats increased the counts of coliforms in the gut whereas the counts of lactobacilli were reduced by yoghurt but not by the base milk. Lactobacillus bulgaricus survived in the guts of gnotobiotic and conventional rats when yoghurt was fed continuously. Streptococcus thermophilus also survived in gnotobiotic rats but its ability to survive in conventional rats could not be examined. Both organisms failed to colonise the gut when a small inoculum of yoghurt was administered orally to germfree rats maintained on the stock diet. Streptococcus thermophilus but not Lact. bulgaricus grew in the rat diet when tested in vitro. Two enzyme systems (beta-galactosidase and lactase) were studied using, respectively, o-nitrophenyl-beta-D-galactopyranoside (ONPG) and lactose as the test substrates. Enzyme levels estimated with both substrates increased in the gut contents when rats were fed yoghurt but an increase was only found with ONPG in the intestinal mucosa fraction. The bacterial origin of all this increased activity is discussed. The other lactose-containing diets did not affect enzyme activity to the same degree. Feeding yoghurt changed the lactobacillus flora from one which was predominantly heterofermentative (Lact. reuteri ) to one which was predominantly homofermentative (Lact. salivarius).

Animals↗
PubMed1996

Note: comparison of media for the isolation of lactose-positive Salmonella.

We studied the capacity of 10 selective media (Rambach agar, RB; salmonella-shigella agar, SS; SM-ID medium, SM; Hektoen enteric agar, HE; modified semisolid Rappaport-Vassiliadis agar, MSRV; bismuth sulphite agar, BS; MacConkey agar, MC; brilliant green agar, BG; novobiocin-brilliant green-glucose agar, NBG; and novobiocin-brilliant green-glycerol-lactose agar, NBGL), and the C8-esterase test (MUCAP test, Biolife, Italy) to detect the growth of 14 strains of lactose-positive Salmonella (12 Salm. virchow and two Salm. montevideo) and 16 Salm. arizonae. Suspensions of pure strain were plated on the aforementioned media and on Mueller-Hinton, used as a control, with inocula of 3 x 10(2) cfu ml-1. The performance of BS was excellent, determining the 30 strains as typical Salmonella colonies (H2S+). On NBG, 27 strains were detected. On MSRV, only some strains grew and only one produced swarming. On the other media, the two Salm. montevideo and the 12 Salm. virchow strains produced coliform colonies. Some of these latter were inhibited on BG and NBGL. The 16 Salm. arizonae strains produced typical colonies on all the media, except on RB, SM and MSRV. On NBGL, two strains did not produce H2S. The C8-esterase test was only successful with Salm. montevideo and Salm. virchow on NBG and RB (with a few exceptions on the latter). However, with Salm. arizonae the test was positive on SS, MC, HE, BG and NBG. In summary, BS was the best medium of those used (all the 30 strains were isolated), followed by NBG (27 isolates).

Culture Media↗
PubMed1990

Towards an understanding of the structural basis of 'forbidden' transport pathways in the Escherichia coli lactose carrier: mutations probing the energy barriers to uncoupled transport.

Recent progress in the analysis of mutants of the Escherichia coli lactose carrier function is reviewed, with special emphasis on the structural basis for energy barriers which prevent 'forbidden' conformational changes. Mutations which break down the barriers to forbidden isomerizations involving the binary carrier:sugar (CS) and carrier:proton (CH) complexes have been obtained in several laboratories. These mutants allow uncoupled transport of H+ or galactoside in the lactose carrier which normally couples cation and sugar movement in a 1:1 stoichiometry. These uncoupled mutants appear to be associated with changes in both sugar and cation recognition, suggesting that the physical interactions forming the basis for co-substrate recognition and uncoupling are not independently variable. By postulating that translocation involves transformation of the stable intermediate of the co-transport cycle to unstable transition state conformations of the carrier, it is possible to consider the consequences of mutagenesis in terms of transition state theory. Consistent with several experimental observations, the analysis predicts in each mutant the occurrence of more than one abnormality in the transport cycle (such as changes in sugar recognition, cation recognition or the coupling reaction). We have called the general phenomenon a 'mutational double-effect' because any mutation which alters the Gibbs free energy change of one reaction in the transport cycle must affect the free energy change of at least one other reaction in this cycle.

Biological Transport↗
PubMed1991

A monoclonal antibody exhibiting reactivity with both X-hapten- and lactose-bearing glycolipids.

The tissue reactivity of a monoclonal antibody raised against human granulocytes, FMC 34, was shown to overlap with antibodies including FMC 10, which is directed against the X-hapten, and with T5A7, which is directed against lactose-bearing antigens. Reactivity of FMC 34 on sections of human cornea was more widespread than that of either FMC 10 or T5A7. High sensitivity fluorescence testing revealed that both FMC 34 and T5A7 reacted weakly with the T-lymphocyte cell line JM, unlike the CD15 antibody FMC 10. Competitive binding experiments showed that binding of FMC 34 to granulocytes was inhibited by preincubation with T5A7, while FMC 34 itself was able to inhibit the binding of both FMC 10 and T5A7. The binding of FMC 10 was not inhibited by preincubation of cells with T5A7. Saturation-binding analyses revealed that each human granulocyte could bind 17.5 x 10(5) molecyles of FMC 34, which was more than three times the number of molecules of FMC 10 which could be bound to each cell. The additional reactivity of FMC 34 appears to be due to its capacity to bind fucosylated and non-fucosylated lactose-bearing structures.

Antibodies, Monoclonal↗
PubMed1991

Submicromolar manganese dependence of Golgi vesicular galactosyltransferase (lactose synthetase).

1. Manganese(II) buffers were set up with inorganic triphosphate, trimethylenediaminetetraacetate and tetramethylenediaminetetraacetate to study the Mn dependence of beta 1,4-galactosyltransferase (lactose synthetase) in preparations of rat mammary gland. 2. In intact particulate preparations, treated with the calcium ionophore A23187, lactose synthesis was abolished by chelators and restored by bivalent transition metal ions in a manner characteristic of activation site I of the pure enzyme. Ni(II) also activated, as did Mg at high concentration. 3. Only Mn(II) could restore endogenous rates, giving an apparent Km of 0.1-0.2 microM, and eliciting about 70% full activity without addition of a site II activator. 4. In purified Golgi membrane vesicles, Mn gave an apparent Km of 0.4 microM. This increased sharply to about 10 microM on permeabilization with filipin, lysis with detergents, solubilization with Triton X-100, or in the pure enzyme. Preparations of chemically undamaged Golgi vesicles, known to include a proportion of the enzyme on exposed membranes, exhibited both low-Km and high-Km components. 5. The response of particulate galactosyltransferase to apparently physiological concentrations of free Mn(II) ion is interpreted as either due to a sensitizing factor within the Golgi lumen, or to the accumulation of Mn at elevated concentrations. Alternatively, the high Km of the soluble enzyme may reflect proteolytic damage.

Animals↗
PubMed1978

Fulminating lactose-positive Vibrio septicemia.

Recently cases of tissue invasion by as yet unnamed marine vibrios which were morphologically and biochemically similar to both Vibrio parahemolyticus and V. alginolyticus, but not identical with either of them, have been described. We have seen a patient who had serious widespread tissue infection with a halophilic, Gram-negative bacterium which was isolated from blood and leg lesions. The organism had the characteristics of the genus Vibrio, and lactose fermentation and ONPG reactions were positive. It also had a lower tolerance for sodium chloride in the nutrient broth compared with the above two vibrios. The isolate seems identical to the lactose positive (L+) Vibrio described by HOLLIS et al. (1976). Tissue infection resulting in severe necrotizing cellulitis and vasculitis was demonstrated at autopsy.

Cellulitis↗
PubMed1990

Lactose- and heparin-inhibitable agglutinin from human fetal brain.

An agglutinin activity which was sensitive to lactose and heparin was estimated during prenatal brain development. The agglutinin showed higher specific activities in cerebral cortex and midbrain. There was an increase in lectin specific activity in all the brain regions with development. In addition to brain, other fetal organs also showed the presence of developmentally regulated agglutinin. Cerebral cortical agglutinin was purified by Sepharose CL-6B gel filtration and asialofetuin- and heparin-Sepharose affinity chromatography. Purified agglutinin was strongly inhibited by lactose, asialofetuin, and heparin. It showed no requirement for divalent cations and was maximally active at pH 8.0. Electrophoretic characterization showed the aggregate nature of the agglutinin, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis gave subunit molecular weights of 58,000, 45,000, and 24,000.

Agglutinins↗
PubMed2006

Immobilized preparation of cold-adapted and halotolerant Antarctic beta-galactosidase as a highly stable catalyst in lactose hydrolysis.

A cold-active beta-galactosidase of Antarctic marine bacterium Pseudoalteromonas sp. 22b was synthesized by an Escherichia coli transformant harboring its gene and immobilized on glutaraldehyde-treated chitosan beads. Unlike the soluble enzyme the immobilized preparation was not inhibited by glucose, its apparent optimum temperature for activity was 10 degrees C higher (50 vs. 40 degrees C, respectively), optimum pH range was wider (pH 6-9 and 6-8, respectively) and stability at 50 degrees C was increased whilst its pH-stability remained unchanged. Soluble and immobilized preparations of Antarctic beta-galactosidase were active and stable in a broad range of NaCl concentrations (up to 3 M) and affected neither by calcium ions nor by galactose. The activity of immobilized beta-galactosidase was maintained for at least 40 days of continuous lactose hydrolysis at 15 degrees C and its shelf life at 4 degrees C exceeded 12 months. Lactose content in milk was reduced by more than 90% over a temperature range of 4-30 degrees C in continuous and batch systems employing the immobilized enzyme.

Animals↗
PubMed1994

Efficient use of lactose for the lac promoter-controlled overexpression of the main antigenic protein of the foot and mouth disease virus in Escherichia coli under fed-batch fermentation conditions.

Derivatives of the lac promoter (tac, pac, rac) belong to the strongest bacterial promoters which are frequently used for the induced overexpression of foreign genes in Escherichia coli. However, their use in fermentation processes is strongly restricted because of the high cost of the inducer iso-propyl-beta-D-thiogalactopyranoside (IPTG). The aim of this work was to investigate the possibility of using lac-derived promoters in high cell density processes resulting in a high yield of the induced recombinant protein if glucose is the main carbon and energy source. Lactose is tested as inducer of the main antigenic coat protein (VP1) of the foot and mouth disease (FMD) virus in a T7-RNA polymerase expression system. It was shown that lactose is able to induce the expression of the recombinant gene to an amount of the VP1 protein corresponding to 20% of the total cell protein.

Antigens, Viral↗
PubMedDate not supplied

Lactose intolerance in a calf.

Lactose intolerance was identified as the cause of bovine neonatal diarrhea. Glucose and xylose oral absorptions were normal whereas lactose absorption was reduced relative to normal calves. Lactase deficiency is common in people but rarely reported in animals. The treatment of whole milk with lactase alleviated the diarrhea.

Absorption↗
PubMed1977

The action of colloidal silicon dioxide as a glidant for lactose, paracetamol, oxytetracycline and their mixtures.

Anomalies are observed in some of the physical and mechanical properties of mixtures of lactose, paracetamol and oxytetracycline when small amounts of colloidal silicon dioxide are added to them. Owing to its differing propensities to coat the particles of the host powders, the silicon dioxide acts as a glidant for the lactose and paracetamol, but as an antiglidant for the oxytetracycline.

Acetaminophen↗
PubMed1979

The granulation of ternary mixtures containing lactose and boric acid with different starches.

Ternary mixtures of lactose, boric acid and starch have been granulated by massing and screening. The properties of the granules have been compared with those resulting from granulation of blends of lactose and boric acid without starch. Potato, maize and rice starches have been studied as the third component at concentrations similar to those employed in tablet formulations. The starches caused a reduction in both mean granule size and granule strength. The effect is dependent on the proportions of the excipients. Increasing the amount of binder solution used gave bigger, stronger granules but did not compensate for the effects produced by the starches.

Boric Acids↗