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PubMed1982

Kinetic constants of lactase of the small intestine of growing rats fully recovered from protein depletion, in relation to dietary protein and lactose concentration.

The effect of dietary composition on the kinetic constants of intestinal lactase was studied using rats depleted of protein by feeding protein-free diet from the weanling stage to 34 days of age and subsequently allowed to recover on diets containing 11.5 or 17% of protein calories (P%) and different levels of lactose (L%; 1, 15, 27 and 37%). After four days of refeeding, rats were decapitated and lactase activity was determined at different substrate concentrations by the method of Dahlqvist using homogenate of intestinal mucosa. Maximum velocity (Vmax) and Michaelis constant (Km) were calculated according to Eisenthal and Cornish-Bowden. At both levels of P%, Vmax tended to increase with the dietary lactose concentration. With diets containing 37% lactose, at P% 11 Vmax was about 60% of that at P% 17.0 Km tended to increase with L% in groups given the 17.0% protein calorie diets, but no difference was observed between groups fed at the lower level of protein. These results can be explained on the basis of interactions between dietary protein at different concentrations and inducer substrate which results in changes in isoenzyme patterns.

Animals↗
PubMed1989

Galactose absorption after oral administration of lactose in neonates.

1. A lactose tolerance test was performed in infants and children. The majority of the infants showed a good response with serum glucose elevations, while there were poor responders among children more than 2 years old. During this test, serum galactose usually was nondetectable, even in the good responders. 2. After simultaneous loading with a constant amount of galactose and varying amounts of glucose in neonates, the degree of elevation of serum galactose levels decreased with increasing amounts of glucose, and loading with equal amounts of galactose and glucose resulted in no elevation of serum galactose levels. 3. In a 6-year-old galactosemic child, serum galactose levels were markedly and continuously elevated after lactose loading. 4. After galactose loading with simultaneous intravenous glucose loading in neonates, elevation of serum galactose was markedly suppressed, as compared with that after galactose loading alone, while it was higher than that after oral loading with the equal doses of galactose and glucose. From the above, the fact that no increase was observed in serum galactose concentration when lactose was loaded orally in neonates is ascribable partially to inhibited absorption of galactose by glucose in the intestine but in the most part to accelerated metabolism of galactose by the glucose absorbed.

Absorption↗
PubMed1993

Effects of cholera and pertussis toxins on prolactin stimulation of lactose synthesis and ornithine decarboxylase activity in mouse mammary gland explants.

Studies indicate that G proteins are likely involved in the signal transduction pathway for prolactin's stimulation of mitogenesis in Nb2 cells. In the mammary gland, little is known about the possible role of G proteins in the prolactin (PRL) stimulation of milk product synthesis. Therefore, the effects of cholera and pertussis toxin, enzymes that modify G protein activity, were tested on several actions of prolactin on mouse mammary tissue in culture. At concentration of 0.1-0.5 micrograms/ml, cholera toxin stimulated ornithine decarboxylase activity in a dose-response fashion; when tested in concert, cholera toxin and prolactin caused an additive response. Cholera toxin by itself did not affect the rate of lactose synthesis, but at concentrations above 0.5 micrograms/ml, it attenuated the magnitude of the prolactin stimulation of lactose synthesis. Pertussis toxin (0-0.5 micrograms/ml), both by itself and in concert with PRL, had no effect on ornithine decarboxylase activity. At concentrations of 25 ng/ml and above, pertussis toxin inhibited the PRL stimulation of lactose synthesis, whereas at 0.2 and 0.5 micrograms/ml, pertussis toxin abolished the PRL response. These observations suggest that a G protein, but not Gs, may be involved in prolactin's mechanism of signal transduction in the mouse mammary gland.

Animals↗
PubMed1991

Comparison of the efficacy of cultures of cecal anaerobes as inocula to reduce Salmonella typhimurium colonization in chicks with or without dietary lactose.

The ability of anaerobic cultures from mature chicken cecal material stored at -70 C for 1 or 10 mo to reduce Salmonella typhimurium colonization of the ceca of young chicks was evaluated. Chick treatments consisted of per os inoculation with anaerobic cultures from the cecal materials and providing or not providing the chicks dietary lactose. Chicks were challenged per os at 3 days of age with 10(6) S. typhimurium. Chicks were killed on Day 10, and their cecal contents were analyzed for pH, oxidation-reduction potential, total short-chained volatile fatty acids (VFA), lactic acid, and the number of S. typhimurium per gram of cecal content. Cecal concentration of undissociated VFA was calculated. Dietary lactose produced a .66- to .87-unit decrease in cecal pH, and significant increases in cecal lactic acid concentrations, undissociated cecal acetic and propionic acid concentrations, and cecal oxidation-reduction potentials. The treatment of the combination of cecal anaerobes from the 1 mo-old cecal material and dietary lactose caused a greater reduction in S. typhimurium cecal colonization than any other treatment.

Animals↗
PubMedDate not supplied

[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↗
PubMed2000

[Effect of the lactose induced diarrhea on macronutrients availability and immune function in well-nourished and undernourished rats].

In this study we compared the availability of nutrients in a balanced diet offered to young well-nourished and undernourished Sprague Dawley rats, with and without diarrhea. Malnutrition was induced by restricting food intake (50%) in one half of the rats for 2 weeks and diarrhea was induced by including 45% lactose in the diet after malnutrition had been established. During the experiment which lasted 8 d the animals were kept on the same feeding protocol but one half of the nourished and one half of the undernourished received lactose to induce diarrhea. The results showed that the inclusion of lactose at 45% in the diet caused a severe diarrhea both in the nourished and undernourished rats. This diarrhea however, resulted in a reduction in food intake and growth only in the well-nourished rats. In the rats with diarrhea the apparent digestibility of the diet and of its macronutrients decreased compared with the animals without diarrhea but this reduction was less apparent in the undernourished rats. Similar results were obtained in relation to the retention of nitrogen and energy. In this case, diarrhea was associated with retentions which were lower than those seen in the rats without diarrhea but the undernourished rats with diarrhea retained more energy than the well-nourished rats with diarrhea. Malnutrition resulted in lower packed cell volume, leukocyte count and thymus weight but diarrhea in the malnourished rats did not cause a further reduction in these variables as it did in the well-nourished animals. In general, these results indicate that in well-nourished rats, diarrhea had a negative effect whereas in the undernourished group it did not. It appears that the undernourished rats compensated their nutrient utilization so that diarrhea did not worsen their undernourished condition.

Animals↗
PubMed1975

The incidence of lactose malabsorption in ulcerative colitis.

120 Danish patients with ulcerative colitis, admitted consecutively to a Department of Gastroenterology, were investigated for lactose malabsorption. The prevalence was 9.2 percent, which is not significantly higher than that in a mixed Danish gastroenterological material, There was no difference in distribution according to age and sex, and the incidence was not correlated to the severity of the ulcerative colitis. The possible reasons for the wide variation in the incidence of lactose malabsorption in materials of patients with ulcerative colitis are discussed, and it is concluded that the main cause must be that the materials with the highest incidence include patients of races and ethnic groups in which lactose malabsorption is a common finding.

Adult↗
PubMed2001

Lactose intolerance.

Lactose intolerance affects more than 50 million Americans. It is one of the most common gastrointestinal disorders seen by primary care physicians. When this disorder is properly diagnosed, the patient is easily treated with education and dietary modifications. Lactose intolerance is commonly misdiagnosed because of its overlapping symptoms of diarrhea and abdominal bloating. This article reviews the etiology, diagnosis, and treatment of lactose intolerance.

Humans↗
PubMed1992

[Relation of lactose levels in milk and indicators of mammary gland health in the first third of lactation].

A total of 662 bucket milk samples from cows of two breed groups were examined: red and white breed = Bohemian Pied cattle with different genetic proportions of Ayrshire and Red Holstein improvement breeds; black and white breed = Black and White Lowland breed and different degree of absorptive crossing with a genetic proportion of the Holstein breed. Samples of daily milk yields were taken in the first three months of lactation once a month within a year. A possibility of using lactose content as an auxiliary indicator for detection of the mammary gland secretion disorders in the initial lactation stage was evaluated. The average values of the different indicators and their variability are summarized in Tab. I showing also the significance in a statistical model of included effects. Lactose content (L) was 4.88 +/- 0.20%, chloride content (Cl-) 113.7 +/- 22.4 mg/100 ml, somatic cell (SC) count 474 +/- 805 thousand/ml, SC count log corresponds to the geometrical mean of 234 thousand/ml, titratable acidity (SH) 7.34 +/- 0.83 x 2.5 mmol/l, chloride-lactose ratio (ClL) 2.27 +/- 0.51, conductivity (gamma) 442.4 +/- 34.5 mS/m and mastitis test (MT-NK) 0.72 +/- 1.18. The efficiency of the used statistical model was highest for Cl- content (Tab. I, R2 = 0.41), and it was lowest for SC counts (R2 = 0.07), while it increased to the twofold value (R2 = 0.15) after logarithmic transformation of SC counts. The breed group exerted a significant effect on Cl-, SC, log SC, SH, ClL, gamma and MT-NK (Tab. I). The breed group of red and white cows (Tab. II) had higher component contents and better indicators of the udder health state (Cl-, SC, log SC, ClL, gamma and MT-NK). The month of lactation influenced significantly SC, log SC, SH and gamma (Tab. I). A decrease in SC counts with the accruing month of lactation was observed (Tab. II), the trend of gamma and SH was opposite. The effect of lactation number was found to be significant for L, SC, log SC, SH, ClL, gamma and MT-NK (Tab. I). A tendency of a gradual decrease with the lactation number was observed in these indicators: L, SH, proteins and solids-non-fat (Fig. 1), while Cl-, gamma and ClL showed an opposite tendency. The year season influenced significantly L, log SC, SH, ClL, gamma and MT-NK (Tab. I, Fig. 2).(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMedDate not supplied

[Effect of glucose and lactose on the utilization of citrate by Lactobacillus casei subsp. rhamnosus ATCC 7469].

The utilization of citrate by Lactobacillus casei subsp. rhamnosus ATCC 7469 in a complex medium containing glucose, lactose or citrate was investigated, as an approach to the question of the transport of this acid and the possible relationship with the production of flavour compounds (diacetyl and acetoin). This lactobacillus uses citrate as an energy source in the absence of carbohydrates. External pH and growth increases when citrate is added to complex medium. The presence of citrate does not affect glucose uptake. L. casei ATCC 7469 possibly uses a transport system for citrate utilization, and citrate uptake seems to be under glucose or lactose control. Lactose only inhibits the entrance of citrate at high concentration while the utilization of this acid was negatively regulated by low glucose concentration.

Biological Transport↗
PubMed2003

[Milk lactose. Hypothesis on its biological importance].

Lactose is the main source of energy supplied to the newborn mammalian in its mother's milk. Because of its lower sweeting power, lactose is unable to induce a reaction as does dextrose. Lactose does not lead to release of mediators such as endorphins or dopamine and is free of reward effects.

Animals↗
PubMed2003

Management of infant diarrhea with high-lactose probiotic-containing formula.

To study the influence of high-lactose probiotic-containing formula on the course of acute diarrhea, an experiment using a randomized controlled clinical trial with patients having acute diarrhea for 3 days was conducted. One hundred patients were allocated into two groups that were comparable for age, sex, and nutritional status. The test group was administered high-lactose Bifidobacterium bifidum-containing formula, while the control group had no high-lactose probiotic until the end of the experiment. The degree of subsequent diarrhea and recovery were monitored in both groups. The results for the test and control groups were analyzed and compared using the chi-square test and Fisher exact test with a significance level (alpha) of 0.05. The study results revealed that there was no significant difference between the test and control groups (p>0.05) as well as at positive clinical test (13%) and positive floating test (65%). However, the patients receiving probiotic-containing formula had significantly less frequency of stools, when compared with the control group (p<0.05).

Acute Disease↗
PubMed2003

Histological changes in intestine in semichronic diarrhoea induced by lactose enriched diet in rats: effect of Diarex-Vet.

Efficacy of Diarex-Vet (The Himalaya Drug Company, Makali, Bangalore, India) was evaluated histologically in semichronic diarrhoea induced by lactose enriched diet in rats. The rats in different groups were given lactose enriched diet alone for 2 days before starting the treatment with Diarex-Vet at a dose of 250, 500 and 750 mg/kg body weight along with lactose enriched diet for 5 days. Animals were euthanised at the end of 5 days of treatment and histological changes were observed in the ileum, caecum and colon. Semiquantitative analysis of goblet cells in intestines showed dose dependent response among the treated groups. The morphological changes were comparable to normal in the group given 750 mg/kg body wt Diarex-Vet. The effects observed were attributed to the lactase like analogous activity of Diarex-Vet or the inhibition of the osmotic processes in the intestinal lumen thereby reducing the morphological changes in the intestines.

Animals↗
PubMed2005

Do probiotics reduce adult lactose intolerance? A systematic review.

PURPOSE: To assess the efficacy of oral probiotics in adults with lactose intolerance through a systematic review of its effects on symptoms and breath hydrogen tests, and whether adding probiotics to nonfermented dairy products decreases lactose intolerance at that meal. METHODS: We searched randomized controlled trials published between 1966 and December 2002. Databases in the search strategy included Medline and AMED. We reviewed references of clinical trials and contacted authors of major articles and manufacturers of probiotic commercial products. Quality assessment was based on the McMaster guides and was performed by 5 independent reviewers. Data extraction was performed by 2 reviewers. RESULTS: A master list of 90 articles was compiled. Ten articles met inclusion and exclusion criteria and were consistent with our clinical question. Of the 9 studies that measured breath hydrogen, 3 were positive, 3 were negative, and 3 had both positive and negative results. Of the 7 studies that measured symptoms, 1 yielded positive results, 5 were negative, and 1 had both positive and negative outcomes. CONCLUSIONS: Probiotic supplementation in general did not alleviate the symptoms and signs of lactose intolerance in adults in this review. Some evidence suggests that specific strains, concentrations, and preparations are effective. Further clinical trials of specific strains and concentrations are necessary to delineate this potential therapeutic relationship.

Administration, Oral↗
PubMed1992

Sequence and specificity of a soluble lactose-binding lectin from Xenopus laevis skin.

A 16-kDa lactose-binding lectin comprises 5% or more of the soluble protein in Xenopus laevis skin. This lectin is mainly localized in the cytoplasm of granular gland cells. In response to stress, the lectin along with a variety of toxic and antibiotic peptides are released onto the skin surface by holocrine secretion. We have purified the lectin, sequenced tryptic peptides using tandem mass spectrometry and Edman degradation, and isolated full-length cDNA using a deduced oligonucleotide. Comparison of the cDNA and peptide sequences revealed expression of at least two isolectins, which differ in sequence at only two or three amino acids. Comparison of cDNA with complementary message by ribonuclease protection confirmed expression in approximately equal abundance of two nearly identical messages. The major soluble lactose-binding lectin expressed in Xenopus muscle is composed of these same isolectins, but at 100-fold lower levels. Similarities and distinctions in sequence and carbohydrate-binding specificity indicate that this lectin is a novel member of a family of soluble lactose-binding lectins expressed in a wide range of vertebrate tissues.

Amino Acid Sequence↗
PubMedDate not supplied

[Genetic and molecular study of inability of the yeast Kluyveromyces lactis var drosophilarum to ferment lactose].

The fermentation of lactose (Lac+) in the dairy yeast Kluyveromyces lactis var. lactis is controlled by the LAC4 (beta-galactosidase) and LAC12 (lactose permease) genes. The complementation analysis of twelve Kl. lactis var. drosophilarum natural homothallic Lac- strains of different origin was carried out using the genetic heterothallic lines of Kl. lactis var. lactis of the lac4LAC12 and LAC4lac12 genotypes. It was shown that the natural Lac- strains did not possess the LAC4LAC12 gene cluster. Southern hybridization of chromosomal DNA with LAC4 and LAC12 probes, as well as recombination analysis, showed that Kl. lactis var. drosophilarum yeasts do not have even silent copies of these genes. As distinct from this yeast, natural Lac- strains of the yeast Kl. marxianus are mutants impaired in the lactose permease gene (lac12 analogue), but possess an active beta-galactosidase gene (LAC4 analogue). The origin of the LAC4LAC12 gene cluster of the dairy yeasts Kl. lactis is discussed.

Fermentation↗
PubMed2006

Fishmeal extract bile salt lactose agar--a differential medium for enteric bacteria.

Fishmeal extract bile salt lactose agar (FEBLA), a new differential medium for enteric bacteria was developed and evaluated for its ability to grow and differentiate lactose fermenters (LF) from non-lactose fermenters (NLF) in comparison with MacConkeys agar. Performance of FEBLA was at par with the latter. On FEBLA medium, the contrast between LF and NLF colonies was pronounced and Klebsiella pneumoniae produced more mucoid colonies than on MacConkeys agar (Hi Media). Unlike MacConkeys agar, a 24 h culture of K. pneumoniae cells on FEBLA were longer and thicker with abundant capsular material around the bacilli. Escherichia coli produced long and thick cells but only after 48h. No change in cell morphology was evident with regard to Salmonella typhi, S. paratyphi A, Shigella flexneri, Pseudomonas aeruginosa, Proteus mirabilis, Proteus vulgaris, Citrobacter koseri and Acinetobacter baumannii. Performance of the medium was controlled using E. coli and S. flexneri. FEBLA is simple, cost effective and may be a suitable alternative in the preliminary identification of enteric bacteria.

Agar↗
PubMed1990

[Use of a fermented powdered milk in malnourished or lactose intolerant children].

Lactase deficient subjects, who form the bulk of the world population, absorb yogurt lactose because the bacteria used for fermentation produce beta-galactosidase. From a milk fermented by these bacteria and dried by a temperature-controlled process a power could be obtained which possess residual lactase activity but, unlike yogurt, does not need storage at low temperature. The lactose of this fermented powdered milk is perfectly absorbed, as proved by hydrogen respiratory tests performed in 35 lactose intolerant African subjects living in isolated villages. In 25 malnourished children under 3 years of age, this milk allowed renutrition without inducing diarrhoea--a result which could not have been obtained with ordinary milk in two-thirds of the cases. This type of food is potentially valuable to feed the large population of the third world.

Adolescent↗