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PubMedDate not supplied

Effect of iron and lactose supplementation of milk on the Maillard reaction and tryptophan content.

New liquid UHT milks supplemented with iron (0.9-1.4 mg/100 ml), vitamin C (1-7 mg/100 ml), lactose (2-4 g/100 ml) and linoleic acid (200-400 mg/100 ml), named growth milks, have recently become available to satisfy the specific nutritional needs of children aged 1-3 years. But the iron-vitamin C mixture could activate the lactose-induced Maillard reaction and tryptophan (Trp) oxidation in proteins. We have therefore examined the Amadori product and Trp concentrations of these milks. Forty-two commercial growth milks from five firms were analysed for the Maillard reaction and the soluble protein Trp content and compared with 64 UHT milks. The furosine concentration of total proteins was two to four times higher in 'growth' milks than in standard UHT milks, indicating a proportional loss of available lysine. The Trp fluorescence of undenatured proteins soluble at pH 4.6 was almost three times lower in 'growth' than in standard milks and Trp concentration 36% lower suggesting destruction of this oxidation-sensitive amino-acid. The mechanism of Trp destruction remains to be elucidated, and the roles of iron and Amadori products determined.

Animals↗
PubMed2004

Transfer of (15)N from oral lactose-ureide to lysine in normal adults.

The metabolic fate of salvaged urea-nitrogen was explored in normal adults who had consumed a diet that provided 36 g protein/day for 7 days. We hypothesised that the colonic microflora utilise nitrogen derived from urea salvage to synthesise lysine in functionally significant amounts for the host. Oral lactose-[(15)N(15)N]ureide is resistant to digestion but is fermented by the colonic microflora to release (15)NH3, which can be used for amino acid synthesis. Prime and intermittent oral doses of lactose-[(15)N(15)N]ureide were ingested for 18 h, urine was collected every 3 h and stools were collected for a further 2 days. Amino acids were isolated from urine and from faecal bacterial protein and the enrichment measured. Compared with baseline values, there was significant enrichment (atoms per cent excess) in faecal bacterial glycine (0.0526), alanine (0.117), lysine (0.0875) and histidine (0.0487), and in urinary glycine (0.016), alanine (0.0144) and lysine (0.0098), but not hisitidine. These data show that the gastrointestinal bacteria can utilise urea-nitrogen in the formation of essential and non-essential amino acids that are available to the host. We estimate that on this low protein diet the amount of lysine from bacterial synthesis and available to the host may be 30 mg/kg/day. These data have important implications for our current perceptions for the dietary requirements for essential amino acids.

Administration, Oral↗
PubMed1997

Metabolic inhibitors as tools to delineate participation of distinct intracellular pathways in enhancement of lactose-induced dissociation of neutrophil and thymocyte aggregates formed by mediation of a plant lectin.

Signaling processes in the course of the formation of the lectin-mediated aggregates may partake in conveying enhanced stability to the cell clusters. To prove the validity of this reasoning in a model, we have studied the impact of addition of three metabolic inhibitors (N-ethylmaleimide, nordihydroguaiaretic acid, and trifluoperazine) on lactose-dependent dissociation of cell aggregates, formed in the presence of the galactoside-binding mistletoe lectin. Using both human neutrophils and rat thymocytes to avoid measurement of responses restricted to a single cell type, an enhanced dissociation of lectin-formed cell aggregates was observed, when lactose and an inhibitor were present. Among the tested inhibitors, nordihydroguaiaretic acid and N-ethylmaleimide were more potent enhancers of cell dissociation than trifluoperazine. These results suggest that biosignalling pathways connected with lipoxygenase activity as well as the level of intracellular sulfhydryl groups confer further stability to lectin-dependent cell aggregates. The systematic evaluation of inhibitors for defined activities is thus suggested as a tool to disclose the nature and the contribution of individual signaling mechanisms to post-binding effects following lectin-initiated cell contact formation.

Animals↗
PubMed2004

Physicochemical characterization of solid dispersions of indomethacin with PEG 6000, Myrj 52, lactose, sorbitol, dextrin, and Eudragit E100.

The purpose of this study was to prepare and characterize solid dispersions of indomethacin with polyethylene glycol (PEG) 6000, Myrj 52, Eudragit E100, and different carbohydrates such as lactose, mannitol, sorbitol, and dextrin. Indomethacin is a class II substance according to the Biopharmaceutics Classification System. It is a poorly water soluble antirheumatic agent. The goal was to investigate whether the solid dispersion can improve the dissolution properties of indomethacin. The solid dispersions were prepared by three different methods depending on the type of carrier. The evaluation of the properties of the dispersions was performed using solubility measurements, dissolution studies, Fourier-transform infrared spectroscopy, and x-ray powder diffractometery. The results indicate that lactose, mannitol, sorbitol, and especially Myrj 52 are suitable carriers to enhance the in vitro dissolution rate of indomethacin at pH 7.2. Eudragit E100, Myrj 52, and mannitol increase the dissolution properties at pH 1.2. The data from the x-ray diffraction showed that the drug was still detectable in its solid state in all solid dispersions except solid dispersions with dextrin and high amounts of mannitol. However, the results from infrared spectroscopy together with those from x-ray diffraction showed well-defined drug-carrier interactions for dextrin coevaporates.

Acrylates↗
PubMed2001

Characterization of wet massing behavior of silicified microcrystalline cellulose and alpha-lactose monohydrate using near-infrared spectroscopy.

The purpose of this study was to investigate the energetic state of water in silicified microcrystalline cellulose (SMCC) and alpha-lactose monohydrate wet masses using near-infrared (NIR) spectroscopy. The applicability of NIR spectroscopy to studying pharmaceutical wet masses at a wide moisture range was evaluated in comparison with mixer torque rheometry (MTR). With increasing moisture content changes in the physical properties of the samples resulted in an apparent increase in log (1/R) throughout the whole spectrum. The upward displacement of baseline and the relative height of water bands were greatest with materials that had a poor liquid-retention capacity. In the case of SMCC and 1:1 mixture of SMCC and alpha-lactose monohydrate, the height of the baseline-corrected water bands increased linearly at low moisture contents, thereafter achieving a plateau stage. According to the MTR results, the plateau stage of the band heights indicated a capillary state of liquid saturation. The second derivative spectrum was capable of distinguishing monohydrate, absorbed, and adsorbed water, which overlapped in the absorbance spectrum. When water was absorbed to the internal structure of the material (SMCC), the water bands were first seen at higher wavelengths, then followed by a shift to lower wavelengths. When water was only adsorbed onto the surface of the particles (glass ballotini), the water bands were seen directly in the region of bulk water.

Crystallization↗
PubMed2003

Exploration of melt granulation technique for the development of coprocessed directly compressible adjuvant containing lactose and microcrystalline cellulose.

The objective of the present investigation was to prepare and evaluate lactose and microcrystalline cellulose based, directly compressible adjuvant using melt granulation technique. The percentage of polymer blend (PVP K 30 and PEG 4000; 5, 10, or 15%) and the polymer blend ratio (9:1, 1:1, or 1:9) were selected as independent variables in a 3(2) full factorial design. The lactose and microcrystalline cellulose blend (3:1) was mixed with the meltable binder on a water bath at 90 degrees C. The agglomerates were cooled to 35 degrees C and subsequently passed through 30 mesh. A batch containing 12.5% of the polymer blend containing 1:9 ratio of PVP:PEG was used for further studies. In an another 3(2) full factorial design, disintegrant (crospovidone, croscarmellose sodium, or sodium starch glycolate) and mode of addition of disintegrant (intragranular, extragranular, or combination of intragranular and extragranular) were used as independent variables. The agglomerates were evaluated for percentage fines and Carr's index. Tablets were prepared on a single-punch tablet machine, and they were evaluated for tensile strength, friability, and disintegration time. Regression analysis was carried out to evolve full and refined models. Contour plots are presented for graphical expression of the results. The use of composite index is demonstrated for the selection of an appropriate batch. The disintegration time of tablets reduced from 18 min to 6 min when 6% crospovidone was included in the product. The optimized adjuvant was characterized for particle size distribution, granular friability, Kawakita's and Kuno's equation, and dilution potential study. Turmeric, glycyrrhiza, acetaminophen, and metformin HCl were used as model drugs for the preparation of tablets. The present study underlines the fact that melt granulation technique may be adopted for the development of multifunctional directly compressible adjuvant for use in pharmaceuticals. The advantages of melt granulation technique over the classical wet granulation and spray-drying are presented.

Adjuvants, Pharmaceutic↗
PubMed1999

Characterization of a targeted gene carrier, lactose-polyethylene glycol-grafted poly-L-lysine and its complex with plasmid DNA.

The physicochemical properties and gene transfer ability of lactose-polyethylene glycol-grafted poly-L-lysine (Lac-PEG-PLL) were investigated. A dye displacement assay showed that plasmid DNA self-assembled with Lac-PEG-PLL, and condensation began at a <1:1 charge ratio of plasmid DNA to polymer. In atomic force microscopy, spontaneously assembled Lac-PEG-PLL/DNA complexes revealed a compact structure, with a size of about 100-200 nm. Circular dichroism spectra of Lac-PEG-PLL/DNA complexes revealed that the secondary structure of DNA was altered by complex formation and was similar to that of the poly-L-lysine/DNA complex. Lac-PEG-PLL was shown to protect DNA against nuclease action in a DNase I protection assay. The cytotoxicity test demonstrated that the complex composed of plasmid DNA and Lac-PEG-PLL had little influence on the viability of HepG2 cells, especially in comparison with that of poly-L-lysine/DNA complexes. In conclusion, our copolymer, Lac-PEG-PLI, formed complexes with plasmid DNA (on average, 150 nm), gave little cytotoxicity, and showed increased efficiency of gene transfer into hepatoma cells in vitro. Lactose-polyethylene glycol was grafted to poly-L-lysine to be used as a gene carrier for hepatoma cell targeting and to improve the solubility of the polyplexes. The average size of the carrier/DNA complexes was about 150 nm. The complexes also proved to have high resistance against nuclease attack and little cytotoxicity. The polymer also delivered plasmid DNA efficiently into a HepG2 cell line. Lac-PEG-PLL was more efficient than Lipofectin or galactose-PEG-PLL in transfection efficiency.

Biological Assay↗
PubMed1997

The inducible lactose operator-repressor system is functional in the whole animal.

Mouse liver cell lines that bear a stably integrated lactose operon repressor (lacI) gene and a Ha-ras gene linked to a lactose operator-containing SV40 early promoter were generated. When grown in medium containing more than 0.1 mM isopropyl beta-D-thiogalactoside (IPTG), the Ha-ras gene was induced up to 20-fold. Maximum induction of Ha-ras gene expression occurred after 12 h of exposure. The tumorigenicity of these cell lines in syngeneic mice was enhanced when the mice were maintained on drinking water containing 12.5 mM IPTG. Ha-ras gene expression in tumors was strongly induced in the presence of IPTG in vivo. Induction of Ha-ras gene expression in mice was consistently observed after 48 hr of exposure to drinking water containing IPTG. This system provides an approach for studying the function of oncogene in vivo as well as other genes of interest.

Animals↗
PubMed1979

Lactose malabsorption in Bangladeshi village children: relation with age, history of recent diarrhea, nutritional status, and breast feeding.

The prevalence of lactose malabsorption (LM) among Bangladeshi village children has been determined using the recent developed breath hydrogen test. Initial hospital-based comparison studies showed general agreement between the breath hydrogen test and a modified lactose tolerance test. Two hundred thirty-four children, stratified by age, nutritional status, and history of recent diarrhea then participated in the field study. LM was diagnosed in more than 80% of children over 36 months of age but in none of the children under 6 months. Rates of LM were significantly increased in children with a history of recent diarrhea and a greater proportion of children in some age groups evidenced malabsorption in association with acute undernutrition. In the weanling age group children who were still breast feeding had a lower rate of LM than fully weaned subjects.

Adolescent↗
PubMed1981

Lactose intolerance in North and South Indians.

A multicenter study was carried out in India to determine the incidence of lactose intolerance in healthy volunteers from different parts of the country. The incidence was found to be 66.6% in the subjects from two South Indian centers at Trivandrum and Pondicherry. In contrast, the incidence in the subjects from a North Indian center in New Delhi was much lower, i.e., 27.4% (p less than 0.001). The lower incidence in the North Indian subjects may perhaps be due to the fact that they are descendants of the Aryans who have been dairying for long and are known to be lactose tolerant.

Adolescent↗
PubMed1989

Cocoa feeding and human lactose intolerance.

On the basis of evidence of the suppressing effect of cocoa on human lactose intolerance, a feeding study was conducted on 35 subjects with a commercial chocolate-milk formula. Variables studied were breath hydrogen level (BHL), symptoms, and onset time. Data from repeated feeding were analyzed by paired t tests. The addition of cocoa significantly reduced BHL (p less than 0.005) as well as the symptom score of both bloating (p less than 0.05) and cramping (p less than 0.025). Individual lactose intolerance levels ranged from 5% (basal milk) to 12.5% with an average of 7.8% upon consumption of 250 mL milk. Having both plain and cocoa formulas contain sucrose and carrageenan led to a conclusion that the suppressive effect of cocoa observed was independent of the presence of sucrose and carrageenan. Ninety-five percent of the subjects responded positively (BHL greater than 17 ppm) to the plain and 51% to the cocoa formula.

Animals↗
PubMed2004

Crystal structures of Erythrina cristagalli lectin with bound N-linked oligosaccharide and lactose.

Erythrina cristagalli lectin (ECL) is a galactose-specific legume lectin. Although its biological function in the legume is unknown, ECL exhibits hemagglutinating activity in vitro and is mitogenic for T lymphocytes. In addition, it has been recently shown that ECL forms a novel conjugate when coupled to a catalytically active derivative of the type A neurotoxin from Clostridium botulinum, thus providing a therapeutic potential. ECL is biologically active as a dimer in which each protomer contains a functional carbohydrate-combining site. The crystal structure of native ECL was recently reported in complex with lactose and 2'-fucosyllactose. ECL protomers adopt the legume lectin fold but form non-canonical dimers via the handshake motif as was previously observed for Erythrina corallodendron lectin. Here we report the crystal structures of native and recombinant forms of the lectin in three new crystal forms, both unliganded and in complex with lactose. For the first time, the detailed structure of the glycosylated hexasaccharide for native ECL has been elucidated. The structure also shows that in the crystal lattice the glycosylation site and the carbohydrate binding site are involved in intermolecular contacts through water-mediated interactions.

Binding Sites↗
PubMed2002

Reproductive defects are corrected in vitamin d-deficient female rats fed a high calcium, phosphorus and lactose diet.

Vitamin D-deficient female rats are capable of reproduction; however, vitamin D deficiency reduces their overall reproductive capacity. It was previously suggested that the reduction in reproductive performance is a direct result of a lack of vitamin D rather than an effect of the hypocalcemia or hypophosphatemia that can be associated with vitamin D deficiency. In the present study, rats were fed one of three diets: 1) 0.47% Ca(+2) and 0.3% phosphorus (P(i)) with vitamin D; 2) 0.47% Ca(+2) and 0.3% P(i) without vitamin D; and 3) 20% lactose, 2% Ca(+2) and 1.25% P(i) without vitamin D. Their reproductive capacity was monitored. Vitamin D-deficient rats fed the high calcium, high phosphorus, 20% lactose diet had normal serum calcium (2.2 +/- 0.16 mmol/L), slightly lower phosphorus (1.5 +/- 0.3 mmol/L), and undetectable 25-hydroxyvitamin D(3). The decrease in reproductive capacity, as indicated by the fertility ratio and pup number per litter previously seen in vitamin D-deficient rats was completely corrected when serum calcium and phosphorus levels were normalized relative to vitamin D-replete rats. It appears likely that the diminished reproductive performance attributed to vitamin D deficiency is the result of hypocalcemia and/or hypophosphatemia caused by vitamin D deficiency.

Animals↗
PubMed1997

Glucose represses the lactose-galactose regulon in Kluyveromyces lactis through a SNF1 and MIG1- dependent pathway that modulates galactokinase (GAL1) gene expression.

Expression of the lactose-galactose regulon in Kluyveromyces lactis is induced by lactose or galactose and repressed by glucose. Some components of the induction and glucose repression pathways have been identified but many remain unknown. We examined the role of the SNF1 (KlSNF1) and MIG1 (KlMIG1) genes in the induction and repression pathways. Our data show that full induction of the regulon requires SNF1; partial induction occurs in a Klsnf1 -deleted strain, indicating that a KlSNF1 -independent pathway(s) also regulates induction. MIG1 is required for full glucose repression of the regulon, but there must be a KlMIG1 -independent repression pathway also. The KlMig1 protein appears to act downstream of the KlSnf1 protein in the glucose repression pathway. Most importantly, the KlSnf1-KIMig repression pathway operates by modulating KlGAL1 expression. Regulating KlGAL1 expression in this manner enables the cell to switch the regulon off in the presence of glucose. Overall, our data show that, while the Snf1 and Mig1 proteins play similar roles in regulating the galactose regulon in Saccharomyces cerevisiae and K.lactis , the way in which these proteins are integrated into the regulatory circuits are unique to each regulon, as is the degree to which each regulon is controlled by the two proteins.

Base Sequence↗
PubMed2001

Predicting evolutionary potential. I. Predicting the evolution of a lactose-PTS system in Escherichia coli.

Genomes contain not only information for current biological functions, but also information for potential novel functions that may allow the host to adapt to new environments. The field of experimental evolution studies that potential by selecting for novel functions and deducing the means by which the function evolved, but until now it has not attempted to predict the outcomes of such experiments. Here I present a model system that is being developed specifically to examine the issue of what kind of information is most useful in predicting how novel functions will evolve. The system is the evolution of a Lac-PTS transport system and a phospho-beta-galactosidase hydrolase system as a novel pathway for metabolism of lactose in Escherichia coli. Two kinds of information, sequence-based phylogenetic inference and biochemical activity, are considered as predictors of which E. coli genes will evolve the required new functions. Both biochemical data and phylogenetic inference predict that the cryptic celABC genes, which currently specify a PTS-beta-glucoside transport system, are most likely to evolve into a PTS-lactose transport system. Phylogenetic inference predicts that the bglA gene, which currently specifies a phospho-beta-glucosidase, is most likely to evolve into a phospho-beta-galactosidase. In contrast, biochemical data predict that the cryptic bglB gene, which also currently specifies a phospho-beta-glucosidase, is most likely to evolve into a phospho-beta-galactosidase.

Base Sequence↗
PubMed2002

Persistent diarrhoea: associated infection and response to a low lactose diet.

Children aged 4-23 months with persistent diarrhoea received a low lactose diet, multivitamins, minerals and antibiotics for infection. Sixty-one (57 per cent) children improved with low lactose diet while 46 (43 per cent) failed. Children who failed were younger (8.9 +/- 3.5 vs. 11.3 +/- 4.4 months), had higher initial purging rate (146 +/- 102 vs. 109 +/- 102 g/kg/day) and consumed more ORS (138 +/- 77 vs. 95 +/- 79 g/kg/day). A higher proportion of children in the failure group needed unscheduled intravenous fluid (48 vs. 20 per cent) and lost body weight (24 vs. 0 per cent). Single and multiple stool pathogen were isolated from 44 and 45 per cent cases, respectively. Diarrhoeagenic Escherichia coli (66 per cent) was the most common pathogen isolated. Half of all pathogens including Campylobacter, rotavirus, cholera and non-typhoidal Salmonella were nosocomially acquired. Sixty four per cent of children had extraintestinal infections including acute lower respiratory infection (50 per cent), urinary tract infection (29 per cent) and septicaemia (11 per cent). The presence of extraintestinal infections were significantly associated with failure. Overall, 91 per cent of children had either intestinal and/or extraintestinal infections.

Age Factors↗
PubMedDate not supplied

Recurrent abdominal pain and lactose maldigestion in school-aged children.

Recurrent abdominal pain of childhood affects 10 to 15% of school-aged children and leads to disability and learning difficulties. Lactose maldigestion may be a causative or contributory factor that when identified may lead to improvement. Thus, formal diagnostic testing using breath hydrogen lactose challenge methods is encouraged. This review focuses on this important condition and management options.

Abdominal Pain↗