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At least 145 records · Page 8Linked to original sources
PubMed1985

Studies on tableting properties of lactose. Part 2. Consolidation and compaction of different types of crystalline lactose.

Lactose is available in several crystalline forms, which differ in binding properties. A new method of estimating the fragmentation propensity was applied to investigate the consolidation and compaction behaviour of this excipient for direct compression. Mercury porosimetry was used to demonstrate that crystalline lactose fragments during compaction. Tablet strength was found to be dependent on the degree of fragmentation only. This finding indicates that the nature of the actual binding must be the same for the different types of crystalline lactose.

Crystallization↗
PubMedDate not supplied

[A medium for rapid and economic identification of Escherichia coli lactose+ colonies: brilliant green-bile-lactose-tryptophan broth].

Among 17 lactose-fermenting species of Enterobacteriaceae (735 strains studied), only Escherichia coli could grow at 44 degrees C in brilliant green/ bile/lactose/L-tryptophan broth (BLBVB-T) with production of gas and indole. When the inoculum was from a lactose+ colony developed on selective or differential agar media commonly used in enteric bacteriology, detection of gas and indole in BLBVB-T after 8 to 18 h incubation at 44 degrees C allowed good identification of E. coli. The use of a single-test medium for the identification of lactose+ E. coli saves time and money.

Bile↗
PubMed1982

Restriction endonuclease analysis of the lactose plasmid in Streptococcus lactis ML3 and two recombinant lactose plasmids.

We investigated the molecular relationship between the 60-megadalton (Mdal) recombinant lactose plasmids in ML 3 x LM2301 lactose-positive (Lac+) transconjugants and the genetic material of Streptococcus lactis ML3. Lactose metabolism is linked to the 33-Mdal plasmid pSK08 in ML3, and the recipient LM2301 is cured of plasmid DNA. The plasmids were analyzed with a series of restriction enzymes. We found that the 60-Mdal plasmids of Lac+ transconjugants contained pSK08 DNA, but were not simply dimers of pSK08. The 60-Mdal plasmids contained a segment of DNA not apparent in pSK08. The restriction patterns of the 60-Mdal plasmid in a Lac+ nonclumping transconjugant and that in a Lac+ clumping transconjugant were different. This suggested that there was a molecular differences between these two recombinant plasmids. We conclude that the segment of DNA in the 60-Mdal plasmids that was not present in pSK08 was the proposed transfer factor responsible for cell aggregation and high-frequency conjugation.

Base Sequence↗
PubMed1984

Lactose transport in Streptococcus mutans: isolation and characterization of factor IIIlac, a specific protein component of the phosphoenolpyruvate-lactose phosphotransferase system.

The transport of lactose in Streptococcus mutans is mediated via an inducible phosphoenolpyruvate-lactose phosphotransferase system. This system requires for catalytic activity a membrane fraction (enzyme II), two general proteins called enzyme I and HPr, and a soluble specific protein termed factor IIIlac. This protein factor was purified from S. mutans ATCC 27352 by chromatographies on DEAE-cellulose, hydroxylapatite, Ultrogel AcA 34, and phosphocellulose. The purified protein migrated as a single band with a molecular weight of 10,000 on polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate and urea. The molecular weight calculated from the amino acid composition was 10,541. Gel filtration of the native protein gave a molecular weight of 41,500. Its isoelectric point was ca. 4.70. A specific antiserum was prepared against purified factor IIIlac. Immunodiffusion experiments revealed that only cellular extracts from lactose-grown cells contained factor IIIlac. A cross-reaction was observed with all of the S. mutans strains tested as well as with Streptococcus sanguis 10556, Streptococcus lactis 11454, and Staphylococcus aureus 6538. No precipitin band was observed with extracts of Streptococcus salivarius, Streptococcus faecalis, Lactobacillus casei, and Bacillus subtilis.

Amino Acids↗
PubMed1989

Comparison of a lactose-free formulation of sodium cromoglycate and sodium cromoglycate plus lactose in the treatment of asthma.

A double-blind, parallel group, 7-centre trial was carried out to compare the clinical efficacy and patient acceptability of two formulations of sodium cromoglycate for inhalation in patients suffering from asthma. Each single-dose capsule for use in a breath-actuated inhaler contained either a blend of sodium cromoglycate (20 mg) plus lactose (20 mg) or a lactose-free pelletized formulation of sodium cromoglycate (20 mg). Data were summarized from 529 asthmatic patients who had been using the blend formulation for at least 3 months previously. Two hundred and sixty-five patients then received pelletized sodium cromoglycate and 264 patients remained on sodium cromoglycate plus lactose for at least 3 months. Regular assessments were made by patients and clinicians during the trial period of treatment effectiveness. No clinically significant differences were observed between the two formulations after 3 months on test treatment. After a treatment period of 6 months, the pelletized formulation was shown to have some advantages over the blend formulation which were not observed at 3 months, with a significantly higher proportion of 'very effective' assessments being recorded by both patients and clinicians. The capsules of pelletized sodium cromoglycate required significantly less inhalations to empty compared to the capsules of the blend. No differences were observed between the two formulations with regard to the incidence of transient cough and throat irritation after inhalation.

Adolescent↗
PubMed1991

An analysis of lactose permease "sugar specificity" mutations which also affect the coupling between proton and lactose transport. I. Val177 and Val177/Asn319 permeases facilitate proton uniport and sugar uniport.

The sugar specificity mutants of the lactose permease containing Val177 or Val177/Asn319 were analyzed with regard to their ability to couple H+ and sugar co-transport. Both mutants were able to transport lactose downhill to a significant degree. The Val177 mutant was partially defective in the active accumulation of galactosides, whereas the Val177/Asn319 mutant was completely defective in the uphill accumulation of sugars. With regard to coupling, the Val177 mutant was shown to catalyze the uncoupled transport of H+ to a substantial degree. This led to a decrease in the H+ electrochemical gradient under aerobic conditions and also resulted in faster H+ uptake when a transient H+ electrochemical gradient was generated under anaerobic conditions. Interestingly, galactosides were shown to diminish the rate of uncoupled H+ transport in the Val177 strain. The Val177/Asn319 strain also catalyzed uncoupled H+ transport, but to a lesser degree than the single Val177 mutant. In addition, the Val177/Asn319 mutant was shown to transport galactosides with or without H+. The observed H+/lactose stoichiometry was 0.30 in the double mutant compared to 0.98 in the wild-type strain. When an H+ electrochemical gradient was generated across the membrane, the Val177/Asn319 mutant permease was shown to facilitate an extremely rapid net H+ leak if nonmetabolizable galactosides had been equilibrated across the membrane. The mechanism of this leak is consistent with a circular pathway involving H+/galactoside influx and uncoupled galactoside efflux. The magnitude of the H+ leak in the presence of nonmetabolizable galactosides was so great in the double mutant that low concentrations of certain galactosides (i.e. 0.5 mM thiodigalactoside) resulted in a complete inhibition of growth. These results are discussed with regard to the possibility that cation and sugar binding to the lactose permease may involve a direct physical coupling at a common recognition site.

Biological Transport↗
PubMed1991

An analysis of lactose permease "sugar specificity" mutations which also affect the coupling between proton and lactose transport. II. Second site revertants of the thiodigalactoside-dependent proton leak by the Val177/Asn319 permease.

The double mutant of the lactose permease containing Val177/Asn319 exhibits proton leakiness by two pathways (see Brooker, R. J. (1991) J. Biol Chem. 266, 4131-4138). One type of H+ leakiness involves the uncoupled influx of H+ (leak A pathway) while a second type involves the coupled influx of H+ and galactosides in conjunction with uncoupled galactoside efflux (leak B pathway). In the current study, 14 independent lactose permease mutants were isolated from the Val177/Asn319 parent which were resistant to thiodigalactoside growth inhibition but retained the ability to transport maltose. All of these mutants contained a third mutation (besides Val177/Asn319) at one of two sites. Eight of the mutants had Ile303 changed to Phe, while six of the mutants had Tyr236 changed to Asn or His. Each type of triple mutant was characterized with regard to sugar transport, H+ leakiness, and sugar specificity. Like the parental strain, all three types of triple mutant showed moderate rates of downhill lactose transport and were defective in the uphill accumulation of sugars. However, with regard to proton leakiness, the triple mutants fell into two distinct categories. The mutant containing Phe303 was generally less H+ leaky than the parent either via the leak A or leak B pathway. In contrast, the triple mutants containing position 236 substitutions (Asn or His) were actually more H+ leaky via the leak A pathway and exhibited similar H+ leakiness via the leak B pathway at high thiodigalactoside concentrations. The ability of the position 236 mutants to grow better than the parent in the presence of low concentrations of thiodigalactoside appears to be due to a decrease in affinity for this particular sugar rather than a generalized defect in H+ leakiness. Finally, the triple mutants showed a sugar specificity profile which was different from either the Val177/Asn319 parent, the single Val177 mutant, or the wild-type strain. These results are discussed with regard to the effects of mutations on both the sugar and H+ transport pathways.

Base Sequence↗
PubMed1982

[Reactions in the rats from prolonged consumption of lactose or hydrolyzed lactose. 3. Crystalline lens].

Three groups of 15 rats Wistar receive a well-balanced diet with 40 per cent of sucrose (T), lactose (P) or hydrolyzed lactose (PH) in the form of ultrafiltration permeate. After 160 days, no cataract is revealed in the T and P groups. In the PH group, 14 rats reached by cataracts in both eyes: it is slightly developed (PH 2), mildly developed (PH 3) or practically total (PH 4). The inositol disappearance, the high quantity of galactitol, the water and sodium increases are the factors observed before the lens opacification and are responsible for the cataract. Then, during the opacification, soluble proteins, potassium and hydratation of the lens decrease. Galactose 1-P is slowly formed before and during the lens opacification. The lens of the P group (lactose) differ from the control group (T) by the nature and the quantity of hexitols, only.

Animals↗
PubMed1997

Increased prevalence of lactose malabsorption in Crohn's disease patients at low risk for lactose malabsorption based on ethnic origin.

OBJECTIVES: The aim of this study was to compare the prevalence of lactose malabsorption (LM) in various subgroups of inflammatory bowel disease patients with controls matched for age, sex, and ethnic origin. METHODS: In 260 patients with IBD [121 Crohn's disease (CD) and 139 ulcerative colitis (UC)] and 158 controls at low and moderate risk for LM the prevalence of lactose malabsorption was determined by H2 breath testing. RESULTS: A control group at low ethnic risk had a prevalence of LM of 29.2% compared with 40.0% in CD (p < 0.025) and 13.3% of ulcerative colitis patients (p < 0.025). No significant differences were observed in comparable groups at moderate risk for LM. Irrespective of ethnic origin, 68.1% of patients with CD limited to the terminal ileum were lactose malabsorbers compared with 43.5% of patients with Crohn's colitis (p < 0.05). Additional analysis according to anatomical location indicated that Crohn's disease of the proximal small bowel (duodenum, jejunum), terminal ileum, terminal ileum plus colon, and colon alone were associated with a prevalence of LM of 100, 68.1, 54.5, and 43.5% respectively. CONCLUSIONS: In patients at low ethnic risk there is a statistically significant increase in the prevalence of LM in CD patients and a decreased prevalence in ulcerative colitis compared with controls.

Adult↗
PubMed1972

Studies on the particulate lactose synthetase of mouse mammary gland and the role of -lactalbumin in the initiation of lactose synthesis.

1. Some of the kinetic properties of the particulate lactose synthetase of mouse mammary gland were investigated and shown to resemble those that have been reported for the soluble enzyme. Typical values for intact preparations were 2.3mum for the apparent K(m) for alpha-lactalbumin at 40mm-glucose and 1.7mm for the apparent K(m) for glucose at the endogenous concentration of alpha-lactalbumin. 2. Digitonin treatment increased total assayable activity approximately twofold but almost eliminated the endogenous activity found in the absence of alpha-lactalbumin, these findings being consistent with the location of endogenous activity within Golgi vesicles. 3. From the properties of the particulate fraction from lactating mice it was deduced that the effective endogenous alpha-lactalbumin concentrations were in the range 1-10mum. 4. The concentration of alpha-lactalbumin was not significantly different in particles isolated at various stages of pregnancy and early lactation. 5. The implications of these results for the control of lactose synthetase in vivo are discussed.

Animals↗
PubMed2000

Randomized multicenter trial documenting the efficacy and safety of a lactose-free and a lactose-containing formula for term infants.

OBJECTIVE: To evaluate the efficacy and safety of a new lactose-free infant formula. DESIGN: Randomized, prospective, double-blind, controlled, outpatient, multicenter, parallel 12-week trial. SETTING: Ambulatory-care facilities of the participating centers. SUBJECTS: 137 healthy term infants (approximately 7 days old at the time of study enrollment). INTERVENTION: Healthy term infants, whose mothers had decided not to breast-feed, were randomly assigned 1 of the 2 study formulas. MAIN OUTCOME MEASURES: Weight, length, and occipitofrontal circumference measurements were obtained at baseline and when the infant was 2, 4, 8, and 12 weeks old. Formula acceptance and tolerance were also assessed at weeks 2, 4, 8, and 12. Serum albumin concentration, creatirune level, and blood urea nitrogen were determined at baseline and week 12. Adverse events were assessed throughout the study. STATISTICAL ANALYSES PERFORMED: Each baseline anthropometric and laboratory variable was analyzed for comparability between groups using the Student t test and was also analyzed using a repeated-measures analysis of variance method. Covariance analysis was applied to the final laboratory data using the respective baseline data as covariates. Decisions about equality of mean responses to formula effects were based on the .05 level of significance in all cases. RESULTS: One hundred four infants completed the study. No significant differences between the 2 formula groups were noted for any of the growth and blood parameters. APPLICATIONS: This new formula is an effective and safe lactose-free nutrition alternative for infants who require such a diet.

Anthropometry↗
PubMed2000

A comparison of color formation and maillard reaction products of a lactose-lysine and lactose-N(alpha)-acetyllysine model system.

The formation of color and Maillard reaction products in two model systems consisting of lactose and lysine or N(alpha)-acetyllysine has been investigated. During heating, the blockage of the N(alpha) group of lysine determined a faster color and antioxidative ability development compared to the system with free lysine. This is combined to a greater amount of melanoidin formation in the acetylated lysine system, while in the free lysine system a higher amount of pyrraline and hydroxymethyl furfural were detected. The pattern of low molecular weight products suggests that 3-deoxyglucosone and 1-deoxyglucosone degradation pathways are favored for free lysine and N(alpha)-acetyllysine, respectively. Whole data allow us to hypothesize that in a lactose-N(alpha)-acetyllysine model system the formation of colored high molecular weight polymer proceeds faster because less material is dispersed in reaction pathways, mainly the Strecker degradation, which leads to small and intermediate molecular weight products.

Antioxidants↗
PubMed1977

Minimal length of the lactose operator sequence for the specific recognition by the lactose repressor.

A number of specific duplex DNA sequences which correspond to varying lengths of the lactose operator region have been synthesized by a combination of chemical and enzymatic methods. Repressor binding studies on these synthetic duplex operator molecules show that all the nucleotides essential for full lactose operator-repressor interactions are included in a 17-nucleotide-long duplex DNA that constitutes the minimal recognition sequence for this DNA-protein interaction.

Base Sequence↗
PubMed1979

[Diagnostic significance of lactose level in milk. 1. Lactose level in first quarter milk samples following artificial udder irritation and infection].

Studies were conducted into lactose levels of milk in response to experimentally irritated or artificially infected udder quarters. Milk lactose was found to be suitable as a model parameter by which to objectivate pathophysiological processes in the udder in the context of research, such as experiments on artificial udder infection or testing of udder tolerance of certain medicaments.

Animals↗
PubMedDate not supplied

[Fragmentation of the lactose-protease plasmid in lactose-negative derivatives of Streptococcus lactis and S. lactis ssp. diacetylactis].

DNA analysis showed the presence of plasmids in all 29 strains of mesophilic lactic streptococci. Their number ranged from 1 to 9 and their molecular weight extended from 1.8 to 45 megadaltons (Md). Comparison of the plasmid profiles from 9 strains of Streptococcus lactis, 3 strains of S. lactis ssp. diacetylactis and from their Lac-,Prt-variants was carried out. In most of the strains, a single plasmid of 27 to 45 Md carried both the lactose and protease (lac and prt) determinants. In Lac- variants, this composite plasmid may at times be lost; in most derivatives, this plasmid was fragmented into several smaller plasmids. Fragmentation resulted in the inactivation of lac genes and often of prt genes; sometimes prt genes remained intact in one of these new plasmids. Fragmentation of the plasmid may also take place without inactivation of these metabolic genes. Restriction analysis of the lactose-protease plasmid from 3 strains of S. lactis and from one Lac-variant confirmed the plasmid fragmentation phenomenon, and led to a proposal for physical mapping of the plasmid and preliminary localization of the lac-prt genes.

DNA Restriction Enzymes↗
PubMed1986

Studies on tableting properties of lactose. Part III. The consolidation behaviour of sieve fractions of crystalline alpha-lactose monohydrate.

The consolidation and compaction behaviour of sieve fractions of crystalline alpha-lactose monohydrate were studied. From mercury porosimetry measurements tablet pore surface areas were derived. At a certain compaction load it appeared that tablets compressed from small particles were generally stronger and showed a larger surface area than compacts prepared from coarse sieve fractions. By plotting compact strength against pore surface area, a unique linear relationship was obtained. From these results it can be concluded that the actual tablet surface area, being a function of both the initial particle size and applied compaction pressure, is responsible for the compact strength.

Chemistry, Pharmaceutical↗
PubMedDate not supplied

Breath hydrogen responses in infants using lactose-rice formula and regular lactose formula.

Starch thickened infant formulas have been shown to relieve regurgitation and increase caloric retention. We compared the completeness of digestion of the carbohydrates in lactose-rice formula (study formula) with routine infant formula in infants with GER. A prospective open study of 30 normal, well-nourished infants with simple regurgitation was conducted. The clinical history on regurgitation, stool pattern and baseline breath hydrogen (bH2) test were obtained at entry, with the infants still using their original routine infant formula, and after a wash out period of 7 days, during which they were fed only with study formula. Analysis of bH2 results showed lower levels of bH2 at 1, 2 and 3 hours with study formula compared with the original formula at the 2nd and 3rd hour (p<0.05). The effectiveness of the study formula in managing GER was demonstrated by the fact that 26 out of 30 had either "some improvement" or a "good response." Hardening of the stool pattern was reported in 13 of the 30 infants after 1 week of study formula. The mean of peak bH2 in study formula fed subjects with formed and firm/hard stool was significantly lower than in those with soft and pasty stool. In conclusion, this study has shown the effectiveness of rice thickened infant formulas in managing infants with GER. Rice-starch has an additional advantage of ease of digestion. The hardening of stool pattern was also frequently observed.

Breath Tests↗