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At least 127 records · Page 7Linked to original sources
PubMed1984

High frequency of lactose absorbers among adults with idiopathic senile and presenile cataract in a population with a high prevalence of primary adult lactose malabsorption.

22% of a group of adult Neapolitans were found to have persistent high lactase activity, and 16% were lactose absorbers as indicated by measurement of breath hydrogen concentration and rise in blood glucose after oral lactose administration. Among adults in the same area with idiopathic senile or presenile cataract 49% were identified as lactose absorbers with the breath hydrogen test and 55% by the rise in blood glucose. These results suggest that adults able to absorb galactose from a lactose-containing diet are especially susceptible to senile or presenile cataract.

Adult↗
PubMed1979

Comparative tolerance of elderly from differing ethnic backgrounds to lactose-containing and lactose-free dairy drinks: a double-blind study.

Milk intolerance was investigated in 87 healthy elderly individuals with a mean age of 77 years who were given 240 ml of a chocolate dairy drink twice in one week with a light lunch. No significant differences in symptomatic responses distinguished the subjects consuming a lactose-free (LF) drink from those consuming a drink containing 4.5% lactose (LC) under double-blind study conditions. Breath hydrogen analysis during lactose tolerance testing identified 23 malabsorbers, none of whom responded exclusively to the LC drink, although five were symptomatic on both days, and two had symptoms only on the day the LF drink was served. A similar percentage of absorbers (72%) and malabsorbers (70%) were asymptomatic on both days. Factors other than lactose malabsorption appeared to be responsible for the symptoms of intolerance reported, and most may have been psychosomatic in origin.

Black or African American↗
PubMed1994

[Modified test with oral lactose loading for detecting lactose intolerance in young children].

Twenty-four children with persistent diarrhea or intestinal dysfunction were examined; lactose, glucose with galactose and lactic acid levels in their feces were not a convincing evidence of lactose intolerance. Detection in the feces of elevated levels of 2 or more parameters after oral lactose load (2 g/kg, not more than 15 g), as well as an increment of a previously elevated value or its manifestation evidenced lactose intolerance. No increase of carbohydrate levels or lactic acid in the feces were observed in the group of 21 age-matched controls.

Child, Preschool↗
PubMed2002

Development of an ultrahigh-temperature process for the enzymatic hydrolysis of lactose. IV. Immobilization of two thermostable beta-glycosidases and optimization of a packed-bed reactor for lactose conversion.

Recombinant hyperthermostable beta-glycosidases from the archaea Sulfolobus solfataricus (Ss beta Gly) and Pyrococcus furiosus (CelB) were covalently attached onto the insoluble carriers chitosan, controlled pore glass (CPG), and Eupergit C. For each enzyme/carrier pair, the protein-binding capacity, the immobilization yield, the pH profiles for activity and stability, the activity/temperature profile, and the kinetic constants for lactose hydrolysis at 70 degrees C were determined. Eupergit C was best among the carriers in regard to retention of native-like activity and stability of Ss beta Gly and CelB over the pH range 3.0-7.5. Its protein binding capacity of approximately 0.003 (on a mass basis) was one-third times that of CPG, while immobilization yields were typically 80% in each case. Activation energies for lactose conversion by the immobilized enzymes at pH 5.5 were in the range 50-60 kJ/mol. This is compared to values of approximately 75 kJ/mol for the free enzymes. Immobilization expands the useful pH range for CelB and Ss beta Gly by approximately 1.5 pH units toward pH 3.5 and pH 4.5, respectively. A packed-bed enzyme reactor was developed for the continuous conversion of lactose in different media, including whey and milk, and operated over extended reaction times of up to 14 days. The productivities of the Eupergit C-immobilized enzyme reactor were determined at dilution rates between 1 and 12 h(-1), and using 45 and 170 g/L initial lactose. Results of kinetic modeling for the same reactor, assuming plug flow and steady state, suggest the presence of mass-transfer limitation of the reaction rate under the conditions used. Formation of galacto-oligosaccharides in the continuous packed-bed reactor and in the batch reactor using free enzyme was closely similar in regard to yield and individual saccharide components produced.

Animals↗
PubMed1984

The interaction of lactose-specific lectins with acid-treated and lactose-substituted sepharose.

The binding of two lectins, one a galactosyl/lactosyl and the other a lactosyl binding protein, to various Sepharose 4B derivatives has been investigated. The adsorbents, lactose-substituted Sepharose, acid-treated Sepharose and acid-treated, lactose-substituted Sepharose, were each tested with regard to their overall binding capacity and for the ability to separate the lectins by differential elution with solutions of galactose and lactose. The binding capacity for both lectins decreased in the order Lac-acid-Sepharose greater than Acid-Sepharose greater than Lac-Sepharose much greater than Untreated Sepharose. The ability of the gels to bind both lectins with a sufficient affinity to allow the proteins to be purified by differential elution decreased in a similar order. Acid-treated, lactose-substituted Sepharose proved the most useful gel and was utilised to isolate each lectin in a pure form.

Animals↗
PubMed2005

Crystal structures of the PNA-porphyrin complex in the presence and absence of lactose: mapping the conformational changes on lactose binding, interacting surfaces, and supramolecular aggregations.

The extraordinary recognition specificity of lectins for carbohydrate ligands appears to be violated as they also bind to porphyrins and other noncarbohydrate ligands. In this study, crystal structures of meso-tetrasulfonatophenylporphyrin (H(2)TPPS) bound to peanut agglutinin (PNA) in the presence and absence of lactose were determined. The binding of H(2)TPPS with PNA involved 11 molecules of H(2)TPPS in different supramolecular stacking arrangements associated with a tetramer of PNA in the crystals of the PNA-H(2)TPPS binary complex as well as the PNA-H(2)TPPS-lactose ternary complex. The ternary complex involved lactose binding only to two subunits of the PNA tetramer, which did not have porphyrin interacting in the vicinity of the carbohydrate-binding site. Comparison of the two structures highlighted the plasticity of the carbohydrate-binding site expressed in terms of the conformational change in lactose binding. The unusual quaternary structure of PNA, which results in exposed protein-protein interaction sites, might be responsible for the porphyrin binding. The association of porphyrin in diverse oligomeric stacking arrangements observed in the PNA-H(2)TPPS complex suggested the possibility of protein-porphyrin aggregation under abnormal physiological conditions. The structures described here provide a possible native conformation of the carbohydrate-binding site of PNA in the absence of the ligand, highlight mapping of the unsaturated binding surfaces of PNA using porphyrin interactions, indicate new leads toward possible application of this lectin in photodynamic therapy, and exhibit diverse modes of porphyrin-lectin interactions with implications to porphyria, a disease that results from abnormal accumulation of porphyrins.

Binding Sites↗
PubMed1976

Chemical and enzymatic synthesis of lactose operator of Escherichia coli and its binding to lactose repressor.

The 21-nucleotide-long duplex DNA constituting the lactose operator sequence of E. coli has been synthesized by both chemical and enzymatic methods. The synthetic duplex has the essential feature of the lactose operator as seen by its binding to the lactose repressor. The binding of the synthetic operator fragment to the lactose repressor is specific because it is inhibited by the inducing ligand isopropyl-beta-D-thiogalactoside. Thus, it is now possible to show that a chemically synthesized oligodeoxynucleotide can be specifically recognized by its natural regulatory protein.

Bacterial Proteins↗
PubMed1991

Acoustic emission during the deformation of alpha-lactose monohydrate and anhydrous alpha-lactose monocrystals.

During the deformation of single crystals of alpha-lactose monohydrate and anhydrous alpha-lactose in a crushing strength rig, their acoustic activity was monitored using a portable activity meter. The acoustic parameters measured were the average signal level (ASL), count rates and total acoustic counts. Both types of lactose, even though deformed by fragmentation, differed fundamentally in the degree and nature of this fragmentation. Close correlation was observed between the ASL, count rate profiles and the force-displacement profiles. The monohydrate form is acoustically more active than the anhydrous form during deformation. Small internal fractures which were neither visually observed nor detected in the force-displacement profiles (in particular the anhydrous alpha-lactose) were detected by monitoring the acoustic signals during the deformation of these crystals. This work illustrates the potential of using the acoustic emission technique as an aid in the assessment of the deformation characteristics of pharmaceutical materials during single crystal compression studies.

Anhydrides↗
PubMed1984

Lactose inhibits the growth of Rhizobium meliloti cells that contain an actively expressed Escherichia coli lactose operon.

Expression of the Escherichia coli lactose operon in Rhizobium meliloti 104A14 made the cells sensitive to the addition of the beta-galactosides lactose, phenyl-beta-D-galactoside, and lactobionic acid. Growth stopped when the beta-galactoside was added and viability decreased modestly during the next few hours, but little cell lysis was observed and the cells appeared normal. Protein synthesis was not inhibited. Growth was inhibited only when beta-galactosidase expression was greater than 160 U. Lactose-resistant mutants had defects in the plasmid-carried E. coli beta-galactosidase or beta-galactoside permease and in the R. meliloti genome. We speculate that uncontrolled production of galactose by the action of the lactose operon proteins was responsible for growth inhibition.

Escherichia coli↗
PubMed1991

Influence of milk, lactose-reduced milk, and lactose on caries in desalivated rats.

There is a growing population who suffer from hyposalivation. These patients frequently sip liquids to alleviate their discomfort. Milk appears to have many of the physical properties of a good saliva substitute. Desalivated rats given 2% milk or lactose-reduced milk remained essentially caries-free. In contrast, animals given sucrose or lactose to drink developed caries. In addition, animals given sucrose or lactose harbored significantly higher populations of Streptococcus sobrinus than did other groups. Results showed that milk and lactose-reduced milk can be used safely by hyposalivatory patients as a saliva substitute.

Animals↗
PubMed1979

[Diagnostic significance of lactose level of milk. 2. Lactose level in first quarter milk samples in various udder disorders].

The behaviour of lactose levels in first quarter milk was studied in the context of a large dairy herd in the presence of various udder health defects. The results were related to other criteria generally used in mastitis diagnosis. The lactose level in first quarter milk was found to be a diagnostic criterion which was properly applicable to detecting and identifying clinical and subclinical mastitis. A limit value of 4.6 per cent has been commonly assumed in literature and proved to be a sound basis for udder health assessment, provided that the given phase of lactation is taken into due consideration (exclusion of cows in the first month post partum as well as of aged milking cows from the seventh month of lactation). Also reported in this paper are results regarding milk lactose and its correlations with other criteria for mastitis diagnosis. A close correlation was found to exist between lactose level and electric conductivity of first quarter milk.

Animals↗
PubMed1983

[Consequences in the rat of prolonged consumption of lactose or hydrolyzed lactose. 4. Composition of the liver].

Lots of 12 rats Wistar receive a well-balanced diet with 40 p. 100 of sucrose (control), or 40 p. 100 of lactose or hydrolyzed lactose in the form of whey or ultrafiltration permeate. After 270 days, the liver of experimental lots contains more thiamine (about +130 p. 100) and less total cholesterol (about -18 p. 100). The lactose feeding increases the liver riboflavine, more than the hydrolyzed lactose.

Animals↗
PubMed1994

Lactose vs. lactose free regimen in children with acute diarrhoea: a randomized controlled trial.

OBJECTIVE: To determine whether the routine use of a lactose free formula (AL-110, Nestle Labs.) in hospitalized children aged one to 24 months reduces the duration of acute diarrhea (AD). METHODS: After being stratified according to age and nutritional state, 28 and 24 patients were randomly allocated to receive AL-110 or lactose formula, respectively. The main outcome was the duration of diarrhoea after refeeding, both in hours and days. Secondary outcomes were evaluated by blind observers. Results were compared using t test, the Mann-Whitney test and Chi square. RESULTS: No differences were found between the diets without and with lactose regarding duration of diarrhoea in hours (mean, 41.9 h vs 54.4 h; p = 0.247) or days (median, 0 d vs 0 d; p = 0.717), the percentage of failures (3.6% vs 8.3; p = 0.2), and the mean weight increment (0.78 kg vs. 0.82 kg; p = 0.788). The study power to find a 50% (27h) reduction of AD duration was 71%. CONCLUSION: Although the power of this trial was slightly below that previously fixed (80%), the results suggest that routine use of lactose free formula does not reduce the duration of AD in hospitalized children.

Acute Disease↗
PubMed1979

Lactose malabsorption and lactose intolerance: implications for general milk consumption.

A total of 194 publications related to lactose malabsorption or intolerance were reviewed. The poor correlation between lactose malabsorption and intolerance to the amounts of milk ordinarily ingested in a meal, indicates that the assumption of milk tolerance by many populations is exaggerated. The methods for the diagnosis of these conditions were critically evaluated and it is suggested that, a) "physiological" doses of lactose be used; b) milk is the vehicle of choice; c) tests of intolerance be double-blind, and d) analysis of breath hydrogen be used for malabsorption. Most of the evidence indicates that milk consumption allows adequate growth of children, even when they are malnourished and have diarrhea. Nevertheless, it is recommended to substitute temporarily non-human milk by other good sources of dietary protein and energy during episodes of severe diarrhea, and to reintroduce milk to the diet gradually during convalescence. Breast feeding, however, should not be interrupted. These is not enough scientific nor epidemiological support to justify discouraging the use of milk in food supplementation programs, but several aspects that must be considered in such programs are outlined.

Adolescent↗
PubMed1968

The lactose synthetase particles of lactating bovine mammary gland. Preparation of particles with intact lactose synthetase.

1. The particulate form of lactating bovine mammary lactose synthetase activity is shown to be more highly organized than previously reported. 2. A novel method of shattering frozen mammary tissue with effective cell disruption is described. 3. The apparent subcellular distribution of lactose synthetase was shown to reflect the method of homogenization. 4. After mild homogenization particles associated with a high content of intact lactose synthetase activity sedimented in the lysosome size range between 5x10(4) and 3x10(5)g-min. 5. Lactose synthetase was dissociated and solubilized by VirTis homogenization and ultrasonic treatment. The activities and behaviour of UDP-galactose hydrolase, succinate dehydrogenase, beta-glucuronidase and phosphodiesterase I were compared. 6. Inhibition of UDP-galactose hydrolase by UTP and alpha-lactalbumin was observed.

Albumins↗
PubMed1994

Dietary lactose intake, lactose intolerance, and the risk of epithelial ovarian cancer in southern Ontario (Canada).

A case-control study of dietary factors and cancer of the ovary was conducted during 1989-92 in metropolitan Toronto and surrounding areas of southern Ontario, Canada. Four hundred and fifty women aged 35-79 years, with newly diagnosed, histologically verified, primary epithelial ovarian-cancer were interviewed concerning reproduction and diet. Over the same period, 564 randomly-selected population controls, frequency-matched to the cases within three 15-year age groups, also were interviewed. From information obtained by quantitative diet history, average daily macro- and micronutrient intake values were calculated through use of the United States Department of Agriculture Food Composition Databank, which was extended and modified for Canadian items and recipes. Analysis was performed with continuous, unconditional logistic-regression methods, adjusting for age at interview, number of full-term pregnancies, total duration of oral contraceptive use, and total daily caloric intake. Neither reported history of lactose intolerance, nor average daily consumption of lactose or free galactose, were found to be associated with risk of ovarian cancer. Lactose intake or intolerance did not appear to modify the protective effects of parity and oral contraceptive use. Nevertheless, other studies suggest that ovarian galactose metabolism still may have a relationship with risk of ovarian cancer, though more evidence is needed.

Adult↗
PubMed1999

A metabolic balance study in term infants fed lactose-containing or lactose-free formula.

Lactose-free (L-) formulas are recommended for infants with conditions affecting lactose digestion. Cows' milk protein-based formulas containing other carbohydrate sources are most often used for such infants. This study compared fat absorption and absorption and retention of nitrogen, calcium, phosphorus, and magnesium in term infants fed either a L- or standard lactose-containing (L+) bovine milk protein-based formula. Data from three single-centre, double-blind, randomized, parallel-group metabolic balance studies were combined. After a 4-7-d equilibration period on either L- or L+ formula, a 72-h balance study was performed. Twenty infants received L- and 21 received L+ formula. Besides the L- group having a higher percentage of males (65%) and the L+ group a higher percentage of females (52.4%), other baseline measurements were similar. The majority of nutrient balance data was similar between the two groups. Exceptions were relative nitrogen absorption, calcium intake and calcium retention, magnesium retention, and faecal phosphorus excretion, all of which were significantly higher in the L- group. Vitamin D supplementation did not significantly affect either calcium or phosphorus data. This new L- formula provided similar nutrients and is a suitable alternative to a L+ formula in term infants requiring L- feedings.

Animals↗
PubMed1982

Effect of fiber on breath hydrogen response and symptoms after oral lactose in lactose malabsorbers.

The effect of ingesting cellulose, pectin, and psyllium with orally administered lactose in water or milk was tested in six lactose malabsorbers. Breath hydrogen tests were used to evaluate lactose malabsorption and mouth-to-cecum transit times. Addition of psyllium significantly reduced the breath hydrogen response, and symptoms in each subject; whereas, less diminution of expired hydrogen was seen after cellulose or pectin was added. The effect of each fiber on gastric emptying rates of an equal volume liquid meal was evaluated in three volunteers. Pectin had no effect, while the cellulose and psyllium modestly delayed emptying at approximately 30 min.

Adolescent↗