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PubMed1998

When to suspect lactose intolerance. Symptomatic, ethnic, and laboratory clues.

Lactose intolerance is widespread, with adult-type hypolactasia being the predominant cause of lactose malabsorption. Daily ingestion of less than 240 mL of milk is well tolerated by most lactose-intolerant adults. Some persons with normal lactase activity may become symptomatic on consumption of products containing lactose. Lactose maldigestion may coexist in adults with irritable bowel syndrome and in children with recurrent abdominal pain. Management consists primarily of dietary changes. People who avoid dairy products should receive calcium supplementation and should be advised to read ingredient labels carefully. Several lactase replacement products are available, but their efficacy varies.

Adolescent↗
PubMed1978

[Hydrolyzed lactose contained in the ultrafiltrate of milk or milk products in an enzymatic membrane reactor].

Milk and milk by-products with a low lactose content, very interesting from a nutritional and technological point of view, were obtained by the application of the enzymatic membrane reactor technique. A previous separation of the aqueous phase of milk or ultrafiltrate was necessary and realized by ultrafiltration. The enzyme, a commercial beta-galactosidase, was maintained in solution in the retentate part of the membrane reactor. The optimal conditions of the lactose hydrolysis in milk and whey ultrafiltrates were determined. The behaviour of the aqueous phase of milk in membrane reactor, specially of mineral salts, was studied. Three possibilities were proposed to avoid a calcium-phosphate deposit on the surface of (and in) the reactor membranes: a precipitation of calcium salts by heating, a partial demineralization by electrodialysis or ion exchange, a calcium complexation by addition of sodium citrate. A continuous process for the lactose hydrolysis of milk and demineralized whey or milk ultrafiltrate was proposed. The organoleptic quality of low lactose milk, before and after heat treatment, was evaluated by a tasting panel. High sweeting syrup, were obtained by concentration of lactose hydrolyzed and demineralized ultrafiltrates. Nutritional aspects of these products are discussed specially from the toxicological point of view of galactose.

Animals↗
PubMed1999

Lactose promotes organized photoreceptor outer segment assembly and preserves expression of photoreceptor proteins in retinal degeneration.

PURPOSE: We have previously shown that lactose promotes the proper assembly of photoreceptor outer segments in the absence of the retinal pigment epithelium (RPE). The purpose of this study was to determine if the difference between organized and disorganized membranes was a variation in the amounts of two structural proteins, opsin and rds/peripherin. METHODS: Eye rudiments were dissected from Xenopus laevis embryos and the RPE was removed prior to culturing in the following media: Niu-Twitty medium; Niu-Twitty with mannose; Niu-Twitty with lactose. Controls included retinas that matured in vitro with an adherent RPE. Photoreceptor ultrastructure was evaluated with emphasis on outer segment membrane organization. The relative amounts of opsin and rds/ peripherin, two outer segment-specific proteins, were determined, as were their immunolabeling patterns. RESULTS: In control retinas, outer segments were composed of stacked, flattened membranous saccules. Opsin labeling of rod outer segments was very dense, indicative of normally organized disc membranes, and rds/peripherin labeling was heavy at the outer segment disc periphery and incisures. In the absence of the RPE, a whorl-like profile of outer segments is present in what would be the sub-retinal space. Opsin immunolabeling was patchy and disorganized. Immunolabeling of rds/peripherin was present, but in a disorderly array. Mannose showed no protective effect. In contrast, lactose promoted the formation of organized outer segments and allowed for near normal expression of both photoreceptor markers. In retinas with disorganized outer segments, the expression of opsin is downregulated while the expression of rds/peripherin is maintained or upregulated. CONCLUSIONS: Lactose protects against the retinal degeneration induced by RPE removal by preserving the outer segment structure and the photoreceptor immunolabeling patterns. It also maintains constant the relative amounts of opsin and rds/peripherin. It is possible that in degenerating retinas, photoreceptors upregulate rds/peripherin expression in attempt to provide additional support for the proper folding of nascent membranes, however this is insufficient to permit organization of the photoreceptor outer segments. Our results suggest that rescue-effect of lactose is mediated by a non-rds/peripherin related mechanism.

Animals↗
PubMed2000

[The influences of lactose as an inducer on the expression of the recombinant proteins in Escherichia coli BL21 (DE3)].

The possibility of using lactose as an inducer to substitute the common inducer IPTG in the fermentation process of the recombinant microorganism was deeply investigated. The influences of culture conditions such as lactose concentration, growth medium composition, the point of induction and the duration of the induction phase on the expression of the recombinant protein were analyzed and studied in detail. In the following experiments, lactose was then used in the high cell density culture process of E. coli BL21 (DE3)(pFu). The final cell density (OD600) was over 40. The expression level of recombinant protein was about 15% of the total cellular protein. Both the culture density and foreign protein expression level were lower than those induced by IPTG. However, because of the potential toxicity to human beings and the high cost of IPTG, the use of lactose might provide an alternative means of inducing foreign protein expression. This would be more attractive in industrial scale productions of recombinant proteins. The results confirmed that lactose could be used as an inducer in the fermentation process.

Dose-Response Relationship, Drug↗
PubMed2002

Development of an ultrahigh-temperature process for the enzymatic hydrolysis of lactose. III. Utilization of two thermostable beta-glycosidases in a continuous ultrafiltration membrane reactor and galacto-oligosaccharide formation under steady-state conditions.

Hydrolysis of lactose by hyperthermophilic beta-glycosidases from the archaea Sulfolobus solfataricus (SsbetaGly) and Pyrococcus furiosus (CelB) was carried out at 70 degrees C in a continuous stirred-tank reactor (CSTR) coupled to a 10-kDa cross-flow ultrafiltration module to recycle the enzyme. Recirculation rates of > or =1 min(-1), reaction of proteins with reducing sugars, and enzyme adsorption onto the membrane are major "operational" factors of enzyme inactivation in the CSTR. They cause the half-life times of SsbetaGly and CelB to be reduced two- and eight-fold, respectively, the average value for both enzymes now being approximately 5 to 7 days. Using lactose at initial concentrations of 45 and 170 g/L, the CSTR was operated at a constant conversion level of approximately 80% for more than 2 weeks without the occurrence of microbial contamination. The productivities for the SsbetaGly-catalyzed conversion of lactose were determined at different dilution rates and initial substrate concentrations, and exceed by a factor of < or =2 those observed with CelB under otherwise identical conditions. This difference reflects the approximately eight-fold stronger product inhibition of CelB by D-glucose. While the maximum total galacto-oligosaccharide production (90-100 mM) at 170 g/L lactose in the CSTR was not different from that in the batch reactor (CelB) or was greater by approximately 25% (SsbetaGly), continuous and batchwise reactions with both enzymes differed markedly with regard to relative proportions of the individual saccharide components present at 80% substrate conversion. The CSTR yielded an up to four-fold greater ratio of disaccharides to trisaccharides concomitant with a 5- to 30-fold larger relative proportion of beta-D-Galp-(1-->3)-D-Glc in the product mixture. The results show that apart from continuous hydrolysis of lactose at 70 degrees C, a CSTR charged with SsbetaGly or CelB and operated at steady-state conditions could be a useful reaction system for the production of galacto-oligosaccharides in which composition is narrower and more easily programmable, in terms of the individual components contained, as compared to the batchwise reaction.

Bioreactors↗
PubMed2006

[Effect of probiotics and yogurt on colonic microflora in subjects with lactose intolerance].

OBJECTIVE: To study the effects of probiotics and yoghurt supplementation on colonic microflora in subjects with lactose intolerance (LI). METHODS: Eleven lactose intolerant volunteers determined by 25g lactose challenge test were recruited and given supplementation with Bifina capsule (with B. longum) and yogurt (with B. animalis, L. bulgaricus, S. thermophilus) for 14 days. The trial was divided into 3 phases: 7-day basal period, 14-day supplementation period and 7-day post-supplementation period. Two lactose challenge tests were performed 1 day before and 1 day after supplementation period respectively, and lactose intolerance symptoms were recorded with questionnaires. Five fecal samples were collected during the trial, and total bacteria and several main groups of bacteria in colon were analyzed by fluorescence in situ hybridization (FISH). The shift of Bifidobacterium species population in colon was analyzed by denaturing gradient gel electrophoresis (DGGE). RESULTS: It was found that LI symptom was alleviated significantly after supplementation (P < 0.05). The amount of total bacteria and the main groups of bacteria (Bifidobacteria, Bacteroides-Prevotella, Eubacteria, Ruminccocc, et al.) was significantly increased during the supplementation period (P < 0.05). The amount of Bifidobacteria during post-supplementation period was significantly higher than that of basal period (P < 0.05), while the amount of other several groups of bacteria decreased. The result of DGGE showed that the extraneous Bifidobacteria species from Bifina capsule and yoghurt could be detected in fecal samples during supplementation period, however there was diversity between volunteers. CONCLUSION: It was suggested that extraneous Bifidobacteria in Bifina capsule and yogurt could resist the effect of gastric acid and bile salt, and survive in colon. Supplementation of probiotics and yogurt could influence the colonic bacteria, and increase the number of main groups of colonic microflora, especially for Bifidobacteria, which could play important role in alleviating LI symptoms.

Adult↗
PubMedDate not supplied

A novel correlation for rapid lactose determination in milk by a cryoscopic technique.

Residual lactose in special milk was systematically determined for people with lactose intolerance by means of a rapid on-line measurement of the cryoscopic point. A proposed cryoscopic procedure was compared to 2 conventional yet highly laborious methods: the enzymatic procedure with spectrophotometric control and the polarimetric method. Several experiments with different mixtures of both semi-skimmed and low-lactose milk were performed. A lineal relationship was found between lactose concentration and freezing point, the analytical equation for which shows a close relationship regarding the 3 methods used. The advantages of the cryoscopic procedure include speed in obtaining results and operational simplicity at a low cost, better monitoring of enzymatic hydrolysis kinetics, and greater control over the production process for delactosed milk. The equation obtained also enables prediction of the lactose percentage in commercial milk by a simple measurement of freezing point.

Animals↗
PubMed1991

The influence of dietary lactose on phosphorus-induced nephrocalcinosis in female rats.

The effect of dietary lactose, when compared with glucose, on phosphorus-induced nephrocalcinosis was studied in young, female rats. Nephrocalcinogenic diets containing either 0.4 or 0.6% (w/w) phosphorus were used, and lactose was added up to concentrations of 30%. The diets were fed for 28 days. The 0.4 and 0.6% phosphorus diets, when compared with a diet containing 0.2% phosphorus, caused mild and severe kidney calcification, respectively; kidney calcification was demonstrated chemically by the analysis of kidney calcium, and histologically by staining kidney slides for calcium deposits. Dietary lactose caused calciuria, decreased urinary pH and increased cecum weights. The addition of lactose to the diet partly counteracted nephrocalcinogenesis induced by diets containing 0.4% phosphorus, but it did not influence the severity of nephrocalcinosis seen in rats fed diets containing 0.6% phosphorus. It is suggested that high amounts of lactose in the diet have only weak anti-nephrocalcinogenic activity.

Animals↗
PubMed1990

[Correlations between lactose-fermenting capacity, sensitivity to antibiotics and bacteriophage types of Salmonella agona strains].

Correlation between the ability to ferment lactose, sensitivity to chemotherapeutic agents and phage type of lactose fermenting and nonfermenting S. agona strains was shown in this study. The difference in sensitivity of two S. agona variants toward gentamicin, tobramycin and chloramphenicol was shown. Lactose fermenting S. agona strains were resistant to the above listed antibiotics. The percentage of the resistant strains was 95.3%, 96.9% and 95.3%, respectively. S. agona strains typable by biochemical tests were more often sensitive to those antibiotics. The percentage of the resistant strains of S. agona with typical biochemical properties was for gentamicin 19.4%, tobramycin 3.7% and chloramphenicol 6.7%. Moreover, the percentage of lactose fermenting S. agona strains resistant to seven other out of seventeen tested antibiotics was 83.8% on average and it was 20% higher than percentage of biochemically typical S. agona strains resistant to the same antibiotics. Lactose fermenting S. agona strains belonged almost four times more frequently to subtype VB and also more often to phage type XI; on the other hand six times rare to phage type I in comparison to biochemically typical S. agona strains.

Anti-Bacterial Agents↗
PubMedDate not supplied

[Experimental dilatation of the cecum and colon in rats. III. A model induced by prolonged administration of lactose in the diet of animals in the chronic phase of infection by the Y strain of T. cruzi].

Female Wistar albino rats (30 days of age), weighing about 60 g, were inoculated intraperitoneally with 1000 parasites/g of the Y strain of T. cruzi. The strain of T. cruzi has been maintained by in vivo passage of the parasites from mice to mice in the Department of Parasitology, Microbiology and Immunology, Medical School of Ribeirão Preto. Rats of the same sex and age were used as controls. One-hundred days after inoculation the animals were allocated into 4 groups: group I (control), divided into subgroup L (fed lactose for 4 weeks) and subgroup S (fed saccharose for 4 weeks); group II (inoculated), divided into subgroup L (fed lactose for 4 weeks) and subgroup S (fed saccharose for 4 weeks); group III (control), divided into subgroup L-S (fed lactose for 4 weeks and saccharose for the following 4 weeks) and subgroup S (fed saccharose for 8 weeks); and group IV (inoculated), divided into subgroup L-S (fed lactose for 4 weeks and saccharose for the following 4 weeks) and subgroup S (fed saccharose for 8 weeks). The disaccharide (lactose or saccharose) was added to a standard laboratory diet, 25 g/100 g of the final weight of the diet. At the end of the experimental periods the animals were sacrificed in ether anesthesia. The volume of the large intestine was measured, and the weight of cecum and colon were recorded.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMedDate not supplied

[Experimental dilatation of the cecum and colon in rats. IV. Evaluation of a model produced by the use of lactose in the food of animals in the chronic phase of infection by the Colombia strain of T. cruzi].

Female Wistar albino rats (30 day of age) were inoculated three times in intervals of 7 days with 1 x 10(7) epimastigote forms of T. cruzi and challenged 30 days after the last inoculation with 1 x 10(5) trypomastigote forms of the Colombia strain of T. cruzi. Rats of the same sex and age were used as controls. One-hundred-fifty days after inoculation the animals were allocated into 4 groups: Group I (control), divided into subgroup L (fed lactose for 4 weeks) and subgroup S (fed saccharose for 4 weeks); Group II (inoculated), divided into subgroup L (fed lactose for 4 weeks) and subgroup S (fed saccharose for 4 weeks); Group III (control), divided into subgroup L-S (fed lactose for 4 weeks and saccharose for the following 4 weeks) and subgroup S (fed saccharose for 8 weeks); and Group IV (inoculated), divided into subgroup L-S (fed lactose for 4 weeks and saccharose for the following 4 weeks) and subgroup S (fed saccharose for 8 weeks). The disaccharide (lactose or saccharose) was added to a standard laboratory diet, 25 g/100 g of the final weight of the diet. At the end of the experimental periods the animals were sacrificed in light ether anesthesia. The volume of the large intestine was measured, and the weights of the cecum and colon were recorded.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

[Effect of lactose on the evaluation of the nutritive value of casein].

The biological evaluation of protein from dairy products such as normal and modified powdered milks where lactose is present, poses difficulties. It is known that when this sugar is contained in high concentrations, and due to its osmotic effect, it causes serious intestinal disorders in rats, thus obstructing the determination of the protein nutritional quality. In the study described herein, efforts were made to determine how lactose affects determination of the nutritional value of casein when this is evaluated by the Net Protein Utilization (NPU) procedure, and by the Relative Net Protein Ratio (RNPR) method. Thirty, and 21-day-old rats were fed with diets containing 10% and 8% of casein respectively, and lactose concentrations varying from 20% to 50%. All experiments lasted 10 days. The results demonstrated that casein's nutritional value did not differ significantly (p greater than 0.05) with lactose concentrations up to 40% in any of both methods, even though intestinal disorders were observed with more frequency and duration as lactose concentration increased.

Animals↗
PubMed1987

Chronic diarrhea and soy formulas. Inhibition of diarrhea by lactose.

Soy protein formulas are often poorly tolerated by infants with chronic nonspecific or postinfectious diarrhea syndrome. We found that these adverse responses may be prevented by using lactose, instead of sucrose or dextrimaltose, in soy formula. We studied 40 infants diagnosed as soy intolerant. They were given soy formula with differing carbohydrate contents in a randomized, blinded prospective study. Stool output, stool sodium content, and symptoms were significantly improved in infants receiving a soy-lactose formula; no difference was seen in formulas with sucrose or maltose. Improvement occurred in three to five days in most infants. Furthermore, the characteristic frequency distribution of the favorable response to lactose suggested a specific mechanism for the inhibition of water and electrolyte losses through the bowel. The results indicate that, in the absence of lactose intolerance, a soy-lactose formula could be useful in treating chronic diarrhea and secondary protein intolerance.

Chronic Disease↗
PubMedDate not supplied

[Study of malabsorption of lactose by the hydrogen breath test in a population of 70 Tunisian adults].

Lactose malabsorption was studied by the hydrogen breath-test in 23 adults suffering from irritable bowel syndrome (group A) and in 47 healthy subjects (group B). The concentration of hydrogen in end-expired alveolar samples was measured after ingestion of 25 g of lactose. Among the 70 subjects, 6 (8.5 p. 100) were not hydrogen producers and were excluded from the study. Lactose malabsorption was shown in 51 of the remaining 64 subjects (79.6 p. 100). Among these 51 patients, 36 were healthy and 15 had an irritable bowel syndrome. The frequency of lactose malabsorption among the 43 healthy hydrogen producers was 83 p. 100. This value is similar to those observed in other studies (greek and italian). Our results suggest that lactose malabsorption is frequent among the tunisian adult population.

Adult↗
PubMedDate not supplied

[Experimental dilatation of the cecum and colon in rats. I. Induction by continuous administration of lactose after weaning].

Female weanling Wistar rats, weighing 30-40 g, were allocated into seven groups (I, II, III, IV, V, VI and VII), and given laboratory rat chow containing ascending concentrations of lactose (subgroup L) and sucrose (subgroup S); each group was administered respectively 0, 5, 10, 20, 25, 30 and 35 g of disaccharide per 100 g final weight of diet. The animals were maintained in these diets for 28 days, when they were weighed and sacrificed. The volume of the large intestine was measured, and the weight of cecum and colon were recorded separately. The values were expressed in cm3/100 g of body weight (volume) and g/100 g of body weight (weight of cecum and colon). The results showed that rats given lactose, except group II (L) showed enlargement of the cecum and colon, as revealed by increased volume and weight, proportionally to the concentration of sugar. This increase was more pronounced in the cecum, while the participation of the colon occurred significantly only with high concentrations of lactose (groups VI (L) and VII (L)). Groups V (L), VI (L) and VII (L) showed very low body weights at the end of the experiment and high mortality rates of respectively 37.5, 50 and 80%. It is postulated that the enlargement of the cecum and colon of rats given lactose is probably related to augmented work due to increased fecal flow through the ileo-cecal valve and/or changes in bacterial flora and fermentation. Besides, the low body weight and the high mortality rate of lactose-fed rats may be dependent on the chronic diarrhea observed in these animals.

Animals↗
PubMed1977

Lactose tolerance in normal Egyptian infants and children and in protein calorie malnutrition.

Oral lactose tolerance test was performed on a total of 100 cases of normal Egyptian infants and children aged 6 months to 12 years. The same test was performed on 30 cases of protein calorie malnutrition (15 cases of marasmus and 15 cases of kwashiorkor). Detection of sugar and determination of pH were also carried out on all stools passed after the test. Lactose intolerance, as judged by a maximal blood glucose rise of 20 mg. or less and/or stools positive for sugar with a pH less than 6 following lactose ingestion, was observed as follows in normal cases: 12% in the age group 6 months to 2 years, 32% in the age group 2 to 5 years, 32% in the age group 5 to 9 years, and 80% in the age group 9 to 12 years. On the other hand, lactose intolerance was demonstrated in 73.3% of cases suffering from protein malnutrition. The aetiology and practical implications of the present findings of lactose intolerance on normal and malnourished children are discussed.

Child↗
PubMed1979

Lactose and casein content of nonpuerperal breast secretion.

Twenty-seven patients with nonpuerperal breast secretion were evaluated for the presence of casein and lactose in the secretions. Only two of seven patients with brownish or greenish secretions were positive for both lactose and casein although an additional six patients were positive for casein alone. Two patients with clear breast secretions were positive for both casein and lactose. However, 16 of 17 patients with milky or white secretions were positive for both casein and lactose. Although casein and lactose are more likely to be present in white breast secretions, other types of breast secretions may also contain these constituents.

Adolescent↗
PubMed1981

Lactose enemas plus placebo tablets vs. neomycin tablets plus starch enemas in acute portal systemic encephalopathy. A double-blind randomized controlled study.

A randomized, double-blind comparison of lactose enemas plus placebo tablets vs. starch enemas plus neomycin tablets was performed on 18 patients with acute portal systemic encephalopathy. Ten patients received starch enemas (10%; 1000 ml t.i.d.) plus neomycin tablets and 8 patients received lactose enemas (20%; 1000 ml t.i.d.) plus placebo tablets. A significant mental state improvement was demonstrated in the group of patients treated with starch enemas-neomycin tablets (p less than 0.05) and in the group of patients treated with lactose enemas-placebo tablets (p less than 0.025). Both treatments significantly improved the frequency of asterixis, ammonia blood levels, and electroencephalograms. In addition, patients treated with lactose enemas showed significant improvement in number-connection test times (p less than 0.02), and their stools showed a more acid pH (p less than 0.05). No side effects were evident with either treatment. Lactose enemas are a safe and effective treatment for acute portal systemic encephalopathy.

Acute Disease↗