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PubMed1993

Evaluating two sources of dried whey and the effects of replacing the corn and dried whey component with corn gluten meal and lactose in the diets of weanling swine.

Three experiments were conducted to evaluate the efficacy of replacing corn and dried whey with corn gluten meal (CGM) and lactose, and to evaluate two sources of edible-grade dried whey that elicited different postweaning pig growth performances. In Exp. 1, two corn-soybean meal (C-SBM) diets without or with 20% dried whey (C-SBM-DW) were formulated to contain 1.15% lysine. A third diet replaced the corn and dried whey component with CGM and lactose. The experiment used 108 crossbred pigs weaned at 23 +/- 2 d of age weighing 6.25 kg BW and was conducted in six replicates as a randomized complete block design. Pig weight gains when the C-SBM-DW diet was fed were poor in one trial, whereas a second trial resulted in improved (P < .01) performance responses to the inclusion of dried whey. The CGM-SBM-lactose diet resulted in pig gains that equaled the performance responses of the C-SBM-DW diet of Trial 2. A second experiment was subsequently designed to evaluate the effects of adding lactose or lactalbumin to the CGM-SBM-DW diets using the two dried whey sources that had been identified as good or poor quality in Exp. 1. Diets included dried whey at a 25% level and were formulated to a low lysine level (.95%) to assess the nutritional efficacy of the dried whey sources.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acids↗
PubMed1997

Influence of galactosyl lactose on energy and protein digestibility, enteric microflora, and performance of weanling pigs.

In three experiments, weanling pigs were used to investigate the effect of feeding .5% galactosyl lactose in a simple corn-soy diet on nutrient digestibility, selected ileal microbial concentrations, fermentation acids, and performance. In Exp. 1, 20 21-d-old weaned pigs in two replicate trials were fed either a 19% CP corn and soybean meal diet or a similar diet containing .5% galactosyl lactose. Feces and urine were collected over a 3-wk period to determine apparent CP and energy digestibilities. Apparent digestibilities of CP and energy were not different between treatments. In Exp. 2, 24 14-d-old nursing pigs were cannulated at the terminal ileum and fed the diets described above after weaning at 21 d of age. Ileal samples were collected at 20, 23, 27, 30, 34, 37, and 41 d of age. Samples were assayed for VFA, lactate, and selected microflora. Ileal fermentation acid concentrations and selected microflora were affected by age of pig but were not different between feed treatments. In Exp. 3, 91 21- to 24-d-old weaned pigs were fed the control and test diets already described; intake, BW gain, and feed efficiency were determined for 9 wk after weaning. Intake was greater in pigs fed galactosyl lactose, but ADG and gain/feed did not differ between treatments. Inclusion of galactosyl lactose in weanling pig diets did not affect protein or energy digestibility, microflora, short-chain fatty acids, or performance of young pigs.

Aging↗
PubMedDate not supplied

Isolation of lactose permease mutants which recognize arabinose.

In the present study lactose permease mutants were isolated which recognize the monosaccharide, L-arabinose. Although the wild-type permease exhibits a poor recognition for L-arabinose, seven independent mutants were identified by their ability to grow on L-arabinose minimal plates. When subjected to DNA sequencing, it was found that all seven of these mutants were single-site mutations in which alanine 177 was changed to valine. The wild type and valine 177 mutant were then analyzed with regard to their abilities to recognize and transport monosaccharides and disaccharides. Free L-arabinose was shown to competitively inhibit [14C]-lactose transport yielding a Ki value of 121 mM for the Val177 mutant and a much higher value of 320 mM for the wild-type. Among several monosaccharides, D-glucose as well as L-arabinose inhibited lactose transport in the Val177 mutant to a significantly greater extent, while D-arabinose and D-xylose only caused a slight inhibition. On the other hand, kinetic studies with sugars which are normally recognized by the wild-type permease such as [14C]-galactose and [14C]-lactose revealed that the Val177 mutant and wild-type strains had similar transport characteristics for these two sugars. Overall, these results are consistent with the notion that the Val177 substitution causes an enhanced recognition for particular sugars (i.e. L-arabinose) but does not universally affect the recognition and unidirectional transport for all sugars. This idea is further supported by the observation that site-directed mutants containing isoleucine, leucine, phenylalanine, or proline at position 177 also were found to possess an enhanced recognition for L-arabinose.

Arabinose↗
PubMed2004

Hydrolysis of lactose in whey permeate for subsequent fermentation to ethanol.

Fermentation of lactose in whey permeate directly into ethanol has had only limited commercial success, as the yields and alcohol tolerances of the organisms capable of directly fermenting lactose are low. This study proposes an alternative strategy: treat the permeate with acid to liberate monomeric sugars that are readily fermented into ethanol. We identified optimum hydrolysis conditions that yield mostly monomeric sugars and limit formation of fermentation inhibitors such as hydroxymethyl furfural by caramelization reactions. Both lactose solutions and commercial whey permeates were hydrolyzed using inorganic acids and carbonic acid. In all cases, more glucose was consumed by secondary reactions than galactose. Galactose was recovered in approximately stoichiometric proportions. Whey permeate has substantial buffering capacity-even at high partial pressures (>5500 kPa[g]), carbon dioxide had little effect on the pH in whey permeate solutions. The elevated temperatures required for hydrolysis with CO2-generated inhibitory compounds through caramelization reactions. For these reasons, carbon dioxide was not a feasible acidulant. With mineral acids reversion reactions dominated, resulting in a stable amount of glucose released. However, the Maillard browning reactions also appeared to be involved. By applying Hammet's acidity function, kinetic data from all experiments were described by a single line. With concentrated inorganic acids, low reaction temperatures allowed lactose hydrolysis with minimal by-product formation and generated a hexose-rich solution amenable to fermentation.

Animals↗
PubMed2006

Influence of calcium and phosphorus, lactose, and salt-to-moisture ratio on Cheddar cheese quality: proteolysis during ripening.

Proteolysis in cheese is influenced by the state of proteins (protein-calcium-phosphate interactions), level of indigenous milk enzymes (plasmin), externally added milk-clotting enzymes (chymosin), and endogenous and exogenous enzymes from starter and non-starter lactic acid bacteria (NSLAB). The objective of this study was to determine how different levels of calcium (Ca) and phosphorus (P), residual lactose, and salt-to-moisture ratio (S/M) in cheese influence proteolysis during ripening. Eight cheeses with 2 levels of Ca and P (0.67 and 0.47% vs. 0.53 and 0.39%, respectively), 2 levels of lactose at pressing (2.4 vs. 0.78%), and 2 levels of S/M (6.4 vs. 4.8%) were manufactured. The cheeses were analyzed for changes in pH 4.6-soluble N, and starter and NSLAB counts during 48 wk of ripening. Cheeses at d 1 were also analyzed for residual chymosin, plasmin, and plasminogen activity. A significant increase in soluble N was observed during ripening for all the treatments. Cheeses with low Ca and P, low lactose, and low S/M treatments exhibited higher levels of proteolysis as compared to their corresponding high treatments. Differences in the rate of proteolysis for cheeses with different levels of Ca and P might be due to changes in protein conformation and differences in residual chymosin in the cheeses. Cheeses with low Ca and P were manufactured by lowering the pH at set and drain, which led to higher chymosin retention in cheeses with low Ca and P compared with high Ca and P. Differences in proteolysis between treatments with different levels of lactose were also partly attributed to residual chymosin activity. In all treatments, a major fraction of plasmin existed as plasminogen, indicating minimal contribution of plasmin to proteolysis in Cheddar cheeses. The number of starter bacteria, in all treatments, decreased significantly during ripening. However, the decrease was larger in the case of high S/M treatments compared with low S/M treatments. In contrast, the number of NSLAB increased during ripening, and low S/M cheeses had higher counts compared with high S/M cheeses. The differences in proteolysis due to S/M were partially attributed to changes in protein conformation or bacterial proteolytic activity.

Calcium↗
PubMed1985

Determination of lactose by an enzymatic method.

The general methodology used for the determination of lactose in milk is considered, namely, polarimetry, gravimetry, infrared, colorimetry, gas-liquid chromatography, and high pressure liquid chromatography. The criteria for selecting an ideal analytical method followed by the relevance of most of these criteria in enzymatic methodology are discussed. The principle of the Boehringer-Mannheim method is presented, i.e., lactose is hydrolyzed to glucose and beta-galactose in the presence of beta-galactosidase and water. beta-Galactose is then oxidized by nicotinamide-adenine dinucleotide to galactonic acid in the presence of beta-galactose dehydrogenase. The amount of reduced nicotinamide-adenine dinucleotide formed is stoichiometric with the amount of lactose and is measured at 340 nm in a spectrophotometer possessing a slit width of less than or equal to 10 nm. The results of a recent Association of Official Analytical Chemists collaborative study of the B-M method are presented. From the overall mean of results on all samples, determinations by the enzymatic method averaged .49% lower than by the Association of Official Analytical Chemists gravimetric method. Standard deviations were similar for three sets of blind duplicates, which ranged between 3.67 and 4.55% lactose. F-Values revealed that variations between means obtained by laboratories differed significantly as compared with variations within laboratory means. The method has received Official First Action recognition by Association of Official Analytical Chemists.

Animals↗
PubMed1993

Role of protein and lactose interactions in the age gelation of ultra-high temperature processed concentrated skim milk.

Skim milk was pasteurized, diafiltered, and concentrated three times by UF. Lactose or sucrose was then added at 3 or 6%. The five samples containing < .05% lactose, 3 and 6% lactose, and 3 and 6% sucrose were UHT processed at 140 degrees C for 4 s using indirect heating, collected aseptically in presterilized containers, and stored at 4, 20, and 35 degrees C. All samples stored at 4 and 20 degrees C gelled after 21 wk of storage. Samples stored at 35 degrees C did not gel. Browning occurred only in samples containing lactose stored at 35 degrees C. Proteolysis in gelled samples was shown by SDS-PAGE. Bands were due to proteolysis, protein crosslinking, and a streaking pattern in ungelled samples. Electron micrographs of gelled samples showed that various casein particles were connected by hairlike protrusions, but the micelles in ungelled samples were not connected and had few protrusions. The Maillard reaction neither promoted nor deferred age gelation. Protein modifications prevented gelation in samples stored at 35 degrees C. Age gelation was probably a two-step process in which dissociated proteins from the casein micelles reformed on micelles as hairlike protrusions. This process was followed by aggregation of the protein particles.

Animals↗
PubMed1997

Body weight gain, feed efficiency, and fecal scores of dairy calves in response to galactosyl-lactose or antibiotics in milk replacers.

Holstein bull calves (n = 96) were purchased at approximately 7 d of age and were assigned to receive 400, 450, 500, and 550 g/d of milk replacer solids during wk 1 to 4, respectively. Treatments were nonmedicated milk replacer plus dried whey, medicated milk replacer (138 mg/kg of oxytetracycline and 276 mg/kg of neomycin) plus dried whey, or nonmedicated milk replacer plus whey processed with beta-galactosidase to contain 15% galactosyl-lactose. Processed whey was added to provide 1% of dry matter as galactosyl-lactose; an equivalent amount of dried whey was added to the other treatments to provide 6.3% of dry matter daily. Intake of milk replacer and fecal scores were measured daily. No calf starter or hay was fed. Body weights were measured weekly from arrival to 26 d. Serum immunoglobulin G, measured 1 d after arrival, averaged 18.3 g/L. Intake of milk replacer plus additive during the 26-d study was 445 g/d and did not vary with treatment. Body weight and body weight gain were increased by 52 and 72 g/d in response to antibiotics and galactosyl-lactose, respectively. Severity of scours and number of days scouring tended to be reduced when calves were fed milk replacer containing galactosyl-lactose or antibiotics.

Animal Feed↗
PubMed1992

Effect of anaerobic cecal microflora and dietary lactose on Salmonella colonization in bobwhite quail (Colinus virginianus).

The effect of oral inoculation with anaerobic cultures of cecal microflora from adult broiler chickens and dietary lactose on Salmonella typhimurium cecal colonization was evaluated in bobwhite quail chicks. One-day-old chicks were divided into four groups and provided 1) no anaerobic cultures, no lactose (control); 2) anaerobic cultures; 3) 2.5% lactose (wt/vol) in drinking water; or 4) anaerobic cultures and lactose. All groups were challenged orally with 10(4) S. typhimurium at 2 days of age. Salmonella growth in the cecal contents was significantly decreased (P < .05) at 15 days of age in each of the three treatment groups as compared with controls. Protection against Salmonella colonization was highest in the treatment group provided anaerobic cultures only. The results indicated that cecal flora from adult chickens enhances Salmonella colonization resistance in quail chicks.

Animals↗
PubMed1994

Effect of cecal cultures encapsulated in alginate beads or lyophilized in skim milk and dietary lactose on Salmonella colonization in broiler chicks.

Cultures of cecal bacteria that were grown under anaerobic conditions were prepared as lyophilized powder or encapsulated and lyophilized in alginate beads and compared with broth cultures for control of Salmonella typhimurium enteric colonization and for ease of delivery in four experiments. Day-old broiler chicks were provided a standard corn-soybean diet with: 1) no culture, no lactose (control); 2) dietary lactose; 3) broth culture by crop gavage; 4) culture in lyophilized powder; or 5) culture encapsulated and lyophilized in alginate beads. Two percent lactose (wt/wt) was included in the diet of chicks in Groups 2 to 5. The lyophilized powder was provided by mixing with the feed. Alginate beads were force-fed or top-dressed on the feed. All groups were challenged on Day 3 with 10(4) cfu of S. typhimurium per chick. Culture by gavage and culture in alginate beads and dietary lactose significantly (P < .05) reduced mean Salmonella colony-forming units in cecal contents by 3.4 to 5.3 log10 units at 10 d of age. Likewise, the number of cecal-culture-positive chicks in the groups provided culture by gavage or in beads was significantly less than controls. Eighty to 90% of the beads provided were consumed by the chicks within 2 h. The results indicated that cultures of cecal bacteria encapsulated and lyophilized in alginate beads were as effective as culture by crop gavage for the reduction of Salmonella colonization in broiler chicks and provide an effective and practical method of delivery.

Alginates↗
PubMed1992

Influence of intestinal parasitism on lactose absorption in well-nourished African children.

Hydrogen breath tests were performed in Gabon (Central Africa) after a loading dose of lactose in 67 well-nourished African children (50 with intestinal parasites and 17 unparasitized) and in 18 unparasitized young adults. All had normal nutritional status, and none had diarrhea or digestive symptoms. Parasites that were found included Ascaris lumbricoides in 76% of the parasitized children, Trichuris trichiura in 58%, Giardia in 24%, Entamoeba histolytica in 20%, Schistosoma intercalatum in 16%, and Necator Americanus in 14%. A similar proportion of parasitized (64%) or unparasitized (62.8%) subjects were lactose malabsorbers. Giardia infection was associated with a higher, but not significantly different, proportion of lactose intolerance (10 of 12, 83.3%). The presence of infection with A. lumbricoides or T. trichiura did not increase the percentage of lactose malabsorption. These data indicate that a decrease of lactase activity in well-nourished African children is not related to the presence or the importance of Ascaris or other intestinal parasites if the nutritional status is normal.

Animals↗
PubMed1997

Provision of lactose to molting hens enhances resistance to Salmonella enteritidis colonization.

Older leghorn hens, more than 50 weeks of age, were divided into three groups designated 1, unmolted controls; 2, molted; or 3, molted treated with lactose. Forced molt was induced by 14 days of feed removal. Lactose was provided to the hens in group 3 as 2.5% (wt/vol) of the daily drinking water. Each hen in all groups was challenged orally with 10(5) Salmonella enteritidis (SE) cells on day 7 of feed removal. The study was repeated in three replicated trials. The concentrations of acetic, propionic, and total volatile fatty acids (VFA) in the cecal contents of the molted hens in groups 2 and 3 decreased significantly (P < 0.05) on days 6 and 14 of molt compared with the unmolted controls. Forced molt had no apparent effect on pH or on the oxidation-reduction potential of the ceca. Compared to the unmolted controls, SE cecal and spleen and liver colonization was significantly increased (P < 0.05) in the molted hens in group 2. Compared to the molted hens in group 2, SE cecal and spleen and liver colonization was significantly decreased (P < 0.05) in two of three trials in the hens in group 3 provided with lactose. The results suggested that the increased susceptibility of molting hens to SE colonization may be associated with decreased fermentation and production of VFA by cecal bacteria or by a depletion of the number of VFA-producing bacteria present in the ceca. The results further suggest that providing lactose in the drinking water during molting may significantly enhance resistance to SE colonization.

Animals↗
PubMed1999

Breast growth and the urinary excretion of lactose during human pregnancy and early lactation: endocrine relationships.

Breast volume and morphology of eight subjects were measured before conception and at intervals throughout pregnancy until 1 month of lactation. Breast volume before conception ranged from 293 to 964 ml. At the end of pregnancy the volume of breast tissue had increased by 145+/-19 ml (mean+/-S.E.M., n = 13 breasts, range 12-227 ml) with a further increase to 211+/-16 ml (n = 12 breasts, range 129-320 ml) by 1 month of lactation. Urinary excretion of lactose increased at 22 weeks of pregnancy, signalling the capacity of the breast to synthesize lactose at this time. During pregnancy, both the change in breast volume and the change in cross-sectional area of the areola were related to the concentration of human placental lactogen in the plasma. The growth of the nipple and the rate of excretion of lactose were related to the concentration of prolactin in the plasma. During the first 3 days after birth, the rate of excretion of lactose was related to the rate of excretion of progesterone. There was no relationship between the growth of the breast during pregnancy and the amount of milk produced at 1 month of lactation.

Adult↗
PubMedDate not supplied

[Influence of lactose rate on calcium fixation in bones. Study in rats].

This investigation was performed to study the effect of lactose on the fixation of calcium in bones of rats. Lactose 3% and 10% concentration was used and the action was compared to that obtained by 67 U.I. of vitamin D in 100 g diet. The data obtained indicated very definitely that the presence of lactose in the diet favorably influences the fixation of Ca in bone, when the amount is 10%; at 3% concentration lactose don't seem influence Ca fixation in bone.

Animals↗
PubMed2002

Overcoming the barrier of lactose intolerance to reduce health disparities.

Federal health goals for the public have focused on reducing health disparities that exist between whites and various racial and ethnic groups. Many of the chronic diseases for which African Americans are at greater risk- hypertension, stroke, colon cancer, and obesity-may be exacerbated by a low intake of calcium and/or other dairy-related nutrients. For example, a low intake of dairy food nutrients, such as calcium, potassium, and magnesium, may contribute to the high risk of hypertension seen in African Americans. The Dietary Approaches to Stop Hypertension (DASH) study demonstrated that a low-fat diet rich in fruits and vegetables (8 to 10 servings) and low-fat dairy foods (3 servings) significantly reduced blood pressure-and was twice as effective in African-American participants. Calcium and dairy food consumption is particularly low among African-American, Hispanic, and Asian populations. Average intakes are near the threshold of 600 to 700 mg/day, below which bone loss and hypertension can result. Although lactose intolerance may be partly to blame for the low calcium intakes due to reduced dairy food consumption by minority populations, culturally determined food preferences and dietary practices learned early in life also play a role. The high incidence figures for primary lactose maldigestion among minority groups grossly overestimates the number who will experience intolerance symptoms after drinking a glass of milk with a meal. Randomized, double-blind, controlled clinical trials have demonstrated that by using a few simple dietary strategies, those who maldigest lactose (have low levels of the lactase enzyme) can easily tolerate a dairy-rich diet that meets calcium intake recommendations. Physicians and other health professionals can help their minority patients and the general public understand how to improve calcium nutrition by overcoming the surmountable barrier of lactose intolerance. At the same time they will be helping to reduce the incidence of calcium-related chronic diseases for which minority populations are at high risk.

Asian↗
PubMedDate not supplied

Lactose intolerance in different types of irritable bowel syndrome in north Indians.

BACKGROUND: Twenty-five patients of irritable bowel syndrome (IBS) and 25 normal healthy individuals serving as controls, were studied for lactose intolerance. METHODS: Hydrogen breath test was used as an investigation after giving 50 g of oral lactose. Clinically, the patients were classified into 3 types of IBS. RESULTS: Eleven (44%) out of 25 patients belonged to diarrhoeal type of IBS, 7 (28%) of 25 patients to spastic and rest 7 (28%) of 25 patients had features of both types of symptoms. Lactose hydrogen breath test was abnormal in 9 cases (82%) of 11 diarrhoeal type of IBS which was significantly higher (p < 0.02) than controls. However, the difference of abnormal hydrogen breath test between spastic type of IBS and patients with features of both types was not significant as compared to controls. CONCLUSIONS: These results suggest that patients with diarrhoeal type of IBS have a higher incidence of lactose intolerance as compared to spastic type as well as patients with features of both types.

Breath Tests↗
PubMed1992

Possible salt bridges between transmembrane alpha-helices of the lactose carrier of Escherichia coli.

Although it is energetically extremely unfavorable to have charged amino acid residues of a polypeptide in the hydrophobic environment of the membrane phospholipid bilayer, a few such charged residues are found in membrane-spanning regions of membrane proteins. Ion pairs (salt bridges) would be much more stable in low dielectric media than single ionized residues. This paper provides indirect evidence for a salt bridge between Asp-240 and Lys-319 in the lactose carrier of Escherichia coli. When Asp-240 was changed to alanine by site-directed mutagenesis, there was a loss of the ability to accumulate methyl-beta-D-thiogalactopyranoside (TMG), melibiose, or lactose. Fast-growing revertants were isolated on melibiose minimal agar plates. Two second-site revertants were isolated: Asp-240-->Ala plus Gly-268-->Val and Asp-240-->Ala plus Lys-319-->Gln. These revertants showed extremely poor accumulation of TMG, melibiose, and lactose, but showed significant "downhill" lactose entry into beta-galactosidase-containing cells with sugar concentrations of 2 and 5 mM. It is concluded that there is some important interaction between Asp-240 and Lys-319, possibly a salt bridge.

Amino Acid Sequence↗
PubMed1992

Nutritional intervention in acute diarrhea: is a lactose-free formula essential?

A prospective study was done to determine the incidence of disaccharide intolerance among 3-36 month-old patients with acute watery diarrhea who were on breast feeding and/or lactose-containing formula. The effect of feeding intervention on the outcome was investigated. Significant disaccharide intolerance was defined as one with (1) biochemical derangements: stool pH < 6.0 (Riedel de Haen pH paper) and reducing substances > or = 0.5 mg% (Clinitest) on two consecutive determinations and (2) clinical evidence: high purging rate (> 10 gm/kg/hour) and reappearance of dehydration and/or weight loss while on a lactose containing milk. Seven of 92 patients (7.8%) had biochemical evidence of disaccharide malabsorption on admission. Subsequent monitoring of the study population showed absence of disaccharide intolerance. Despite a lactose containing formula, a significant (p < 0.05) reduction in stool output from the first to the second day (145.85 +/- 130.26 vs 115.43 +/- 95.65 g/kg admission weight) was noted. Likewise, weight gain from admission to discharge (4.56 +/- 3.44%) was observed. The mean total duration of illness (4.75 +/- 2.84 days) was well within the usual course of five to seven days. This study supports the current recommendation of continued breast feeding and/or use of lactose containing formula during acute watery diarrhea.

Acute Disease↗