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PubMed1986

Hypercholesterolemia and aortic glycosaminoglycans of rabbits fed semi-purified diets containing sucrose and lactose.

This study was designed to evaluate the role of dietary sucrose and lactose in a semipurified diet as initiating factors for aortic glycosaminoglycan (GAG) and lipid changes. Rabbits were fed sucrose or lactose as 40% by weight of a semi-purified, cholesterol-free diet for 10 weeks. At the end of the feeding period there was no macroscopic evidence of atherosclerosis. Sucrose-fed rabbits had significantly higher plasma cholesterol and phospholipid levels than the lactose-fed rabbits and triglyceride levels were variably elevated in the sucrose group. Analysis of plasma lipoproteins indicated that sucrose elevated VLDL and LDL when compared to lactose. Only the higher molecular weight form of apo B (apo BH) could be demonstrated when apo B components of isolated lipoproteins were analyzed. Sucrose-fed rabbits had significantly more aortic cholesterol, cholesteryl ester and phospholipid and tended to have more GAG/mg dry defatted aorta than the lactose-fed rabbits. Plasma cholesterol levels correlated with aortic lipids and in the sucrose group, aortic cholesteryl ester and cholesterol were strongly correlated with aortic GAG particularly hyaluronic acid. Results suggest that the semi-purified diet alters aortic GAG composition but in order for the initiation of cholesterol accumulation a significant increase in plasma lipoprotein cholesterol is necessary.

Animals↗
PubMed1993

Effects of glucose, galactose, and lactose ingestion on the plasma glucose and insulin response in persons with non-insulin-dependent diabetes mellitus.

Galactose usually is ingested as lactose, which is composed of equimolar amounts of glucose and galactose. The contribution of galactose to the increase in glucose and insulin levels following ingestion of equimolar amounts of galactose and glucose, or lactose, has not been reported in people with non-insulin-dependent diabetes mellitus (NIDDM). Therefore, we studied the effects of galactose ingestion alone, as well as with glucose either independently or in the form of lactose, in subjects with untreated NIDDM. Eight male subjects with untreated NIDDM ingested 25 g glucose, 25 g galactose with or without 25 g glucose, or 50 g lactose as a breakfast meal in random sequence. They also received 50 g glucose on two occasions as a reference. Water only was given as a control meal. Plasma galactose, glucose, glucagon, alpha-amino nitrogen (AAN), nonesterified fatty acids (NEFA), and serum insulin and C-peptide concentrations were determined over a 5-hour period. The integrated area responses were quantified over the 5-hour period using the water control as a baseline. Following ingestion of 25 g galactose, the maximal increase in plasma galactose concentration was 1 mmol/L. The mean maximal increases in plasma galactose concentration following ingestion of 25 g galactose + 25 g glucose or following 50-g lactose meals were similar and were only 12% of that following ingestion of galactose alone (P < .05). The mean galactose area response over the water control for the 25-g galactose meal was 0.95 +/- 0.31 mmol.h/L.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1987

Antibody response to haptenic sugar antigen: immunodominancy of protein-bound lactose formed by amino-carbonyl reaction.

Several reducing sugars with structural analogy (glucose, galactose, lactose, melibiose, maltose and cellobiose) were bound to a carrier protein ovalbumin by amino-carbonyl reaction, and the non-enzymatically glycosylated proteins were injected into mice (BALB/c, C57BL/6, DBA/2 and C3H/He strains) with Freund's adjuvant. Antibody responses to the haptenic sugar antigens were analyzed quantitatively by enzyme-linked immunosorbent-assay using each sugar-bovine serum albumin complex. The haptenic sugar antigen from lactose induced a markedly higher response of specific antibody as compared with the haptenic sugar antigens from the other sugars. The antibody raised against the lactose adduct reacted well with lactulose (4-o-beta-D-galactopyranosyl-D-fructose) or alpha-N-acetyl-epsilon-N-deoxylactulosyl-L-lysine. The results suggested that immunogenicity of haptenic sugar antigens was remarkably different in sugar chemical structure, and that the lactose adduct formed by lactose-protein amino-carbonyl reaction could be an immunodominant antigenic determinant.

Amino Acids↗
PubMed2006

Glass transition and enthalpy relaxation of amorphous lactose glass.

The glass transition temperature, T(g), and enthalpy relaxation of amorphous lactose glass were investigated by differential scanning calorimetry (DSC) for isothermal aging periods at various temperatures (25, 60, 75, and 90 degrees C) below T(g). Both T(g) and enthalpy relaxation were found to increase with increasing aging time and temperature. The enthalpy relaxation increased approximately exponentially with aging time at a temperature (90 degrees C) close to T(g) (102 degrees C). There was no significant change observed in the enthalpy relaxation around room temperature (25 degrees C) over an aging period of 1month. The Kohlrausch-Williams-Watts (KWW) model was able to fit the experimental enthalpy relaxation data well. The relaxation distribution parameter (beta) was determined to be in the range 0.81-0.89. The enthalpy relaxation time constant (tau) increased with decreasing aging temperature. The observed enthalpy relaxation data showed that molecular mobility in amorphous lactose glass was higher at temperatures closer to T(g). Lactose glass was stable for a long time at 25 degrees C. These findings should be helpful for improving the processing and storage stability of amorphous lactose and lactose containing food and pharmaceutical products.

Calorimetry, Differential Scanning↗
PubMed2005

A new innovative process to produce lactose-reduced skim milk.

The research field for applications for lactose hydrolysis has been investigated for some decades. Lactose intolerance, improvement for technical processing of solutions containing lactose and utilisation of lactose in whey are main topics in development of biotechnological processes. In this article, the establishment of a hollow fiber membrane reactor process for enzymatic lactose hydrolysis is reported. Mesophilic beta-galactosidases were circulated abluminally during luminal flow of skim milk. The main problem, microorganisms growth in the enzyme solution, was minimised by sterile filtration and UV irradiation. In order to characterise the process parameters, such as skim milk concentration, enzyme activity and flow rates were varied. In comparison to a batch process, enzyme activity could be used longer and enzyme rest into the product should not occur. Furthermore, the three-dimensional separation of the substrate from the enzyme solution minimise blocking and washing out effects, which restrict processes with immobilised enzymes. A conversion rate of 78.11% was achieved at a skim milk flow rate of 9.9l h(-1), enzyme activity of 120 Uml(-1) and a temperature of 23+/-2 degrees C in a hollow fiber reactor with a membrane area of 4.9 m2.

Animals↗
PubMed2004

Hydrogen breath test in the diagnosis of lactose malabsorption: accuracy of new versus conventional criteria.

Increased hydrogen excretion in the breath after carbohydrate ingestion, an expression of carbohydrate malabsorption, represents the pathophysiologic basis of the hydrogen breath test, a simple, noninvasive, reproducible test for the diagnosis of this condition. Few data are available concerning the breath hydrogen response that most accurately identifies carbohydrate malabsorption. In this article we report our application for the first time in clinical practice of 2 recently described, more accurate criteria for the diagnosis of lactose malabsorption (ie, breath hydrogen excretion value > 6 parts per million (ppm) 6 hours after carbohydrate load and a sum greater than 15 ppm for the breath hydrogen values obtained 5, 6, and 7 hours after carbohydrate load). On 3 separate days, we subjected 84 consecutive patients with functional or organic gastrointestinal disease to measurement of hydrogen excretion in the breath after the administration of lactose to test for lactose malabsorption; after the administration of lactulose as a means of ruling out false-negative results resulting from hydrogen-nonproducer status; and after the administration of a nonabsorbable electrolyte solution as a means of ruling out false-positive results caused by the mixing of intestinal content and release of preformed hydrogen trapped in the feces. According to the conventional criterion, 51% of the subjects proved to be lactose malabsorbers. Positive results were obtained with the use of the 6th-hour criterion in 76% of patients, and positive results were found in 80% when the sum of the excretion at hours 5, 6, and 7 was used as the criterion (P < .05 for both comparisons). Ten of 21 and 11 of 25, respectively, showed intolerance symptoms. It was therefore possible for us to diagnose lactose malabsorption in 24% and 27% of patients, respectively, who tested negative according to the conventional criterion. The conventional criterion must be abandoned and these new criteria adopted.

Adult↗
PubMed1991

The alkaline anthraquinone-2-sulfonate-H2O2-catalyzed oxidative degradation of lactose: an improved Spengler-Pfannenstiel oxidation.

The alkali-catalyzed oxidative degradation of lactose (1) to potassium O-beta-D-galactopyranosyl-(1----3)-D-arabinonate (2) has been studied and compared with that of D-glucose to D-arabinonate and D-galactose to D-lyxonate. A mechanism for the degradation of 1 catalyzed by alkali only is presented and discussed, taking into consideration the main reaction products. Increasing the reaction temperature from 293 to 318 K resulted in a drastic decrease of the selectivity for 2. Increasing the oxygen pressure from 1 to 5 bar did not significantly influence the selectivity. The overall reaction kinetics followed first-order behavior with respect to lactose, D-glucose, or D-galactose. The simultaneous addition of catalytic, equimolar amounts of sodium 2-anthraquinonemonosulfonate and H2O2 showed a pronounced effect on the selectivity. A reaction mechanism for this type of alkali-catalyzed oxidative degradation of carbohydrates is presented and discussed. Lactose could be oxidized up to almost complete conversion with a selectivity of 90-95% (mol/mol), whereas D-glucose was oxidized to D-arabinonate with a selectivity of 98%. This increased selectivity was maintained at temperatures from 293 up to 323 K, allowing a reduction of the batch time necessary for almost complete conversion from 50 to 1.5 h. The overall reaction kinetics still followed first-order behavior with respect to lactose, D-glucose or D-galactose. The apparent activation energy amounted to 114 +/- 2 kJ mol-1 for lactose, to 109 +/- 2 kJ mol-1 for D-glucose, and to 104 +/- 9 kJ mol-1 for D-galactose.

Alkalies↗
PubMed1979

[Interaction between ricin hemagglutinin and its ligands, galactose and lactose. Microcalorimetry and equilibrium dialysis].

The interaction of Ricinus communis hemagglutinin with galactose and lactose has been studied by means of microcalorimetry, equilibrium dialysis and analytical ultracentrifugation. A first class of beta-galactoside-binding sites involves two similar and independent sites of which affinity constants are 2600 M-1 for galactose and 26700 M-1 for lactose at 25 degrees C. The binding of one galactose or one lactose molecule leads to enthalpy changes of--12.3 Kcal and--11 Kcal, respectively. Considering the negative entropy changes of the association, and as for ricin, the binding of galactosides with hemagglutinin is driven by favorable enthalpic contributions. In presence of high lactose concentrations, a second endothermic step of the calorimetric titration curve was observed. This result and the biphasic nature of Scatchard plots of equilibrium dialysis suggest the existence of a second class of binding sites on the lectin molecule. As for ricin, the interaction between these secondary sites and lactose would be entropically driven.

Agglutinins↗
PubMed1999

Development of dried liposomes containing beta-galactosidase for the digestion of lactose in milk.

The hydrolyzed-lactose milk for lactase-deficient subjects has a sweeter taste than whole milk, and some subjects dislike its taste. In order to cope with this shortcoming, we examined whether beta-galactosidase, which hydrolyzes lactose, added to the whole milk in the form of dried liposomes, would be able to digest lactose in milk following the lysis of liposomes in the presence of bile salts. Dried liposomes containing beta-galactosidase were prepared in the presence of trehalose by the dehydration-rehydration vesicle method to overcome the instability of the conventional liposome suspension. The stability of liposomal membranes was evaluated by measuring the activity of entrapped beta-galactosidase under various storage conditions. By treating liposomes with trehalose, which was found to prevent the fusion of liposomes and the leakage of entrapped drug, the entrapping efficiency increased up to fourfold. Over 95% of dried liposomes which had been stored at 17 degrees C for 60 days were reconstituted to liposomes upon rehydration process. From the stability study, dried liposomes were found to retain 87% of beta-galactosidase activity at 17 degrees C after 60 days and to be more stable than the multilamellar vesicle suspension prepared without trehalose. The lysis study showed that dried liposomes were hardly lyzed in the simulated gastric fluid with pepsin, but lyzed immediately more than 90% in 0.01 M deoxycholic acid. Lactose hydrolysis in the presence of deoxycholic acid after the addition of dried liposome-entrapped beta-galactosidase to whole milk was proportional to the quantity of entrapped beta-galactosidase and the amount of dried liposomes added. These results demonstrate that beta-galactosidase entrapped in liposome is stable and reconstituted mostly upon rehydration, and can digest lactose in milk after the efficient lysis of liposomes in the presence of bile salts. This study implies that beta-galactosidase entrapped in liposome may be applied to whole milk for lactase-deficient subjects.

Animals↗
PubMed1998

Dry powder inhalers: the influence of device resistance and powder formulation on drug and lactose deposition in vitro.

It is a principal in the formulation of a dry powder aerosol that the device should enable a high fine particle fraction (FPF) of drug to be delivered to the lung whilst any carrier, such as lactose, should remain in the upper airways. Both the device and the dry powder formulation itself contribute to the resultant FPF and few studies have considered the deposition of lactose carrier. It was the purpose of this study to determine the effect of the resistance of the device and the influence of powder formulation on the deposition of drug and carrier. Measurement of the pressure drop across the devices investigated in this study showed that the two types of Inhalator Ingelheim had the highest resistance, whilst lower pressure drops were found across the Diskhaler, Cyclohaler and Accuhaler devices. The lowest pressure drops were measured across the Rotahaler and Spinhaler devices. Employing Rotacaps 400 capsules as the formulated salbutamol product, the FPF of drug was greater from the high resistance devices, being in the order Inhalators Ingelheim>Cyclohaler>Rotahaler=Spinhaler. However, the Diskhaler, employing its own developed formulation, produced the highest FPF, approximately twice that from the Accuhaler. There was no statistical difference between the FPF of salbutamol (approximately 20% nominal dose) from the Rotacaps formulation when aerosolised using high resistance devices (Inhalators Ingelheim) operated at 30 l min-1, a medium resistance device (Cyclohaler) operated at 60 l min-1 and low resistance devices (Spinhaler and Rotahaler) operated at a flow-rate of 90 l min-1. The Ventolin Diskhaler using its own formulation operated at 60 l min-1 gave a FPF of 40.33%, but the FPF obtained was sensitive to flow, being only 25.65% of the nominal dose at 30 l min-1. Whereas no lactose was found in the FPF from the Accuhaler operated at 60 l min-1, 100, 400 and 3500 microg were obtained from the Diskhaler, Rotacaps and micronised lactose formulation, respectively, when operated at the same flow-rate. An in-house formulation comprising salbutamol sulphate blended with micronised lactose in a weight ratio of 1:67.5 and aerosolised from a Cyclohaler produced a similar FPF to the Diskhaler at 60 l min-1. When air flow was reduced to 30 l min-1, the FPF from the in-house formulation was reduced considerably less than that from the Diskhaler formulation.

Adrenergic beta-Agonists↗
PubMedDate not supplied

Lactose-poly(ethylene glycol)-grafted poly-L-lysine as hepatoma cell-tapgeted gene carrier.

To investigate the delivery of DNA into cells, lactose-poly(ethylene glycol)-grafted poly-L-lysine (Lac-PEG-PLL) polymers were synthesized as polymeric gene carriers. The new synthetic carriers, varying the substitution ratio of lactose-poly(ethylene glycol) (lactose-PEG), were characterized by NMR spectroscopy and size-exclusion chromatography. Electrophoretic mobility assay confirmed that the new gene carrier makes a complex with plasmid DNA. The attached poly(ethylene glycol) gives better solubility properties to gene/carrier complex. Transfection experiments showed that Lac-PEG-PLL efficiently delivers DNA to a hepatoma cell line in vitro; the best efficiency was achieved at a 1:3 weight ratio of DNA to carrier. As the lactose-PEG substitution content increased up to 30%, the transfection efficiency increased, which demonstrates that the lactose serves as a targeting moiety. No considerable cytotoxicity was observed due to Lac-PEG-PLL or its complex with DNA within the concentration range for this experiment. The use of chloroquine increased transfection efficiency that indicates the involvement of hydrolytic degradation of the system in lysosome. It is likely that plasmid DNA/Lac-PEG-PLL complexes enter the cells through a receptor-mediated endocytosis mechanism. These results show that Lac-PEG-PLL can form a complex with plasmid DNA and serve as an efficient gene delivery carrier with lower cytotoxicity compared to that of poly-L-lysine. Therefore, it is expected that our Lac-PEG-PLL carrier can be used as an in vivo gene delivery vector.

Animals↗
PubMed1997

Cysteine-scanning mutagenesis of helix II and flanking hydrophilic domains in the lactose permease of Escherichia coli.

Using a functional lactose permease mutant devoid of Cys residues (C-less permease), each amino acid residue in putative transmembrane helix II and flanking hydrophilic loops (from Leu34 to Lys74) was replaced individually with Cys. Of the 41 single-Cys mutants, 28 accumulate lactose to > 70% of the steady state observed with C-less permease, and an additional 10 mutants exhibit lower but significant levels of accumulation (25-60% of C-less). His35-->Cys permease exhibits very low activity (ca. 20% of C-less), while Gly64-->Cys or Asp68-->Cys permease is unable to accumulate lactose. However, His35 can be replaced with Arg without effect on transport activity [Padan, E., Sarkar, H.K., et al. (1985) Proc. Natl. Acad. Sci. U.S.A. 82, 6765-6768]. In addition, even though mutant Gly64-->Cys or Glu68-->Cys is inactive both in the C-less background and in the wild-type, neither Gly64 [Jung, K., Jung, H., et al. (1995) Biochemistry 34, 1030-1039] nor Glu68 [Jessen-Marshall, A.E., & Brooker, R.J. (1996) J. Biol. Chem. 271, 1400-1404] is essential for active lactose transport. Immunoloblot analysis reveals that all of the mutants except His35-->Cys permease are inserted into the membrane at concentrations comparable to that of C-less permease. The transport activity of the single-Cys mutants is altered by N-ethylmaleimide (NEM) treatment in a highly specific manner. Most of the mutants are insensitive, but Cys replacements render the permease sensitive to NEM inactivation at positions that cluster in a manner indicating that they are on one face of an alpha-helix (Thr45-->Cys, Gly46-->Cys, Phe49-->Cys, Ser53-->Cys, Ser56-->Cys, Gln60-->Cys, and Ser67-->Cys). Interestingly, the same face contains positions where Cys substitution itself leads to low transport activity (Ile52-->Cys, Leu57-->Cys, Gln60-->Cys, and Gly64-->Cys). The results demonstrate that although no residue per se in this region of the permease is irreplaceable, the surface of one face of helix II is important for active lactose transport.

Amino Acid Sequence↗
PubMedDate not supplied

Synthesis of poly(L-lactide) end-capped with lactose residue.

The synthesis of poly(L-lactide) (polyLA) end-capped with lactose residue was studied from the standpoint of development of a new bioabsorbable material. After the hydroxyl group of t-butoxycarbonyl(Boc)-aminoethanol was converted to Boc-aminoethanol-OK by using potassium/naphthalene, L-lactide was polymerized in tetrahydrofuran using Boc-aminoethanol-OK as an initiator at room temperature to prepare polyLA-NHBoc. Subsequently, the removal of the Boc group in terminal Boc-aminoethanol residue was performed by treatment of formic acid to obtain the amino group end-capped polyLA (polyLA-NH(2)) as a reactive polyLA derivative. The coupling reactions of lactose with polyLA-NH(2) were investigated by two methods; the synthetic method through reductive amination of lactose with polyLA-NH(2) in the presence of sodium cyanoborohydride as a reducing agent did not give high degree of substitution of end-capped lactose residue per polyLA molecule, whereas the synthetic method through the ester interchange reaction of lactonolactone with polyLA-NH(2) gave Lac-polyLA perfectly end-capped with lactose residue.

Amination↗
PubMedDate not supplied

Immobilization of beta-galactosidase on fibrous matrix by polyethyleneimine for production of galacto-oligosaccharides from lactose.

The production of galacto-oligosaccharides (GOS) from lactose by Aspergillus oryzae beta-galactosidase immobilized on cotton cloth was studied. A novel method of enzyme immobilization involving PEI-enzyme aggregate formation and growth of aggregates on individual fibrils of cotton cloth leading to multilayer immobilization of the enzyme was developed. A large amount of enzyme was immobilized (250 mg/g support) with about 90-95% efficiency. A maximum GOS production of 25-26% (w/w) was achieved at near 50% lactose conversion from 400 g/L of lactose at pH 4.5 and 40 degrees C. Tri- and tetrasaccharides were the major types of GOS formed, accounting for about 70% and 25% of the total GOS produced in the reactions, respectively. Temperature and pH affected not only the reaction rate but also GOS yield to some extend. A reaction pH of 6.0 increased GOS yield by as much as 10% compared with that of pH 4.5 while decreased the reaction rate of immobilized enzyme. The cotton cloth as the support matrix for enzyme immobilization did not affect the GOS formation characteristics of the enzyme under the same reaction conditions, suggesting diffusion limitation was negligible in the packed bed reactor and the enzyme carrier. Increase in the thermal stability of PEI-immobilized enzyme was also observed. The half-life for the immobilized enzyme on cotton cloth was close to 1 year at 40 degrees C and 21 days at 50 degrees C. Stable, continuous operation in a plug-flow reactor was demonstrated for about 3 days without any apparent problem. A maximum GOS production of 26% (w/w) of total sugars was attained at 50% lactose conversion with a feed containing 400 g/L of lactose at pH 4.5 and 40 degrees C. The corresponding reactor productivity was 6 kg/L/h, which is several-hundred-fold higher than those previously reported.

Aspergillus oryzae↗
PubMedDate not supplied

Crystallization and X-ray diffraction of crystals formed in water-plasticized amorphous lactose.

Effects of storage time and relative humidity on crystallization and crystal forms produced from amorphous lactose were investigated. Crystallization was observed from time-dependent loss of sorbed water and increasing intensities of peaks in X-ray diffraction patterns. The rate of crystallization increased with increasing storage relative humidity. Lactose crystallized mainly as alpha-lactose monohydrate and anhydrous crystals with alpha- and beta-lactose in a molar ratio of 5:3. The results suggested that the crystal form was defined by the early nucleation process. The crystallization data are important in modeling of crystallization phenomena and prediction of stability of lactose-containing food and pharmaceutical materials.

Crystallization↗
PubMed2005

Two types of radicals in whole milk powder. Effect of lactose crystallization, lipid oxidation, and browning reactions.

Whole milk powder was stored in closed vials at 60 degrees C to induce crystallization of lactose within a short time scale. After an induction period of 3-4 days simultaneous crystallization of lactose, increase of water activity, formation of browning products, and increase of radical content took place. Radicals detected before lactose crystallization were characterized by a narrow ESR spectrum (g = 2.006) and could be depleted by removal of oxygen and therefore were assigned to oxidation processes. Late-stage radicals present after crystallization of lactose gave much wider spectra (g = 2.0048) and were independent of oxygen availability and assigned to late-stage Maillard reaction products. The study indicates that the processes of lactose crystallization, browning, and formation of radical species (g = 2.0048) are strongly coupled, while lipid oxidation is less dependent on the other processes.

Animals↗
PubMed1999

Formation of stable covalent dimer explains the high solubility at pH 4.6 of lactose-beta-lactoglobulin conjugates heated near neutral pH.

The solubility of lactose-beta-lactoglobulin conjugates at pH 4.6, after heating near neutral pH in phosphate buffer/0.116 M NaCI, was investigated by size exclusion chromatography and compared with unmodified protein. Heated conjugates in the temperature range 65-90 degrees C showed greater solubility at pH 4.6. The proportion of soluble protein increased with the number of bound lactose molecules. Total solubility was obtained for conjugates with nine lactose residues attached per monomer of beta-lactoglobulin. The protective effect of bound sugar toward precipitation was associated with the formation of soluble disulfide cross-linked dimers, highly accessible to trypsin digestion. These results suggested that bound lactose, through steric hindrance and high surface hydrophilicity, prevents the thiol-disulfide exchange reactions of the polymerization-aggregation process of lactose-beta-lactoglobulin conjugates.

Chromatography, Gel↗
PubMed2001

Comparison of yoghurt, heat treated yoghurt, milk and lactose effects on plasmid dissemination in gnotobiotic mice.

The effect of yoghurt, heat-treated fermented milk, milk and lactose solution intake on plasmid transfer and establishment of the resulting transconjugants in the digestive tract of mice colonised with human faecal flora were examined. Yoghurt lowered the population level of transconjugants more efficiently than heat-treated fermented milk (-2 log and -1 log respectively) and indicated a beneficial effect of viable bacteria. On the other hand consumption of milk drastically inhibited the establishment of transconjugants, which were below the detection threshold of 10(2) UFC per g of faeces. We were not able to recover transconjugants from faecal samples with lactose supplementation, indicating a possible inhibition of plasmid transfer. Since the yoghurt, heat-treated fermented milk, milk and lactose solution contained approximately the same lactose concentration it is fair to speculate that lactose may contribute to the inhibiting effects of the various supplementations. The inhibitions described were not associated with other intestinal parameters like the intestinal transit time, the population levels of the recipient, or the donor and total anaerobic microflora. It is evident that other parameters need to be investigated such as the composition of the endogenous microflora and metabolic products.

Animals↗