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PubMed2004

Evaluation of SCF-engineered particle-based lactose blends in passive dry powder inhalers.

The objective of this study was to assess the performance of SCF-engineered budesonide and albuterol sulfate powder blends in passive dry powder inhalers (DPI) relative to micronized drug blends. A number of lactose grades for inhalation were screened and the appropriate carrier and drug-to-lactose blending ratio were selected based on drug content and emitted dose uniformity. Aerosol performance was characterized by Andersen cascade impaction. Blend formulations of SEDS (solution enhanced dispersion by supercritical fluids) budesonide and albuterol exhibited a significant drug content uniformity (7-9% RSD) improvement over micronized drug blends (16-20% RSD). Further, the SEDS formulations demonstrated higher emitted dose and reduced emitted dose variability (10-12% RSD) compared to micronized powders (21-25% RSD) in the Turbospin, albeit without significant enhancement of the fine particle fraction. In contrast, SEDS powders exhibited increased fine particle fractions over micronized blends in the Clickhaler; improvements were more pronounced with albuterol sulfate. The performance enhancements observed with the SEDS powders are attributed to their increased surface smoothness and reduced surface energy that are presumed to minimize irreversible drug-carrier particle interactions, thus resulting in more efficient drug detachment from the carrier particle surface during aerosolization. As demonstrated for budesonide and albuterol, SEDS may enhance performance of lactose blends and thus provide an attractive particle engineering option for the development of blend formulations for inhalation delivery.

Administration, Inhalation↗
PubMed2005

Kinetic study of the Maillard reaction between metoclopramide hydrochloride and lactose.

The purpose of this work is to study the apparent solid-state kinetics of the Maillard reaction of the colyophilized metoclopramide hydrochloride (MCP) and lactose system and to elucidate some of the effects of molecular mobility on the kinetic behavior of the amorphous mixture. Colyophilized MCP-lactose mixtures (1:9 molar ratio) were stored at temperatures ranging from 100 to 115 degrees C (above the glass transition temperature, Tg=99.7 degrees C). This temperature range, which corresponds to the change between the glass and liquid states of the lactose-MCP mixtures, is also the temperature region where molecular mobility represents a kinetic impediment of enough significance as to affect the observed order of the reaction. A pseudo second-order kinetic model was developed to fit the MCP loss data. The proposed model gives better fit to the degradation data than many of the commonly used kinetic models available in the literature. The second-order rate constant of the model follows Arrhenius kinetics and the activation energy was found to be 53.8 kcal mol(-1). The molecular mobility (relaxation time) of the mixture was calculated from the heating rate dependence of the DSC-determined glass transition temperature of the mixtures. From molecular mobility considerations alone, it is possible to accurately predict the temperature dependence of the reaction rate constant. These results support the hypothesis that the solid-state reaction is mobility controlled.

Freeze Drying↗
PubMed2006

Elastic modulus measurements from individual lactose particles using atomic force microscopy.

The elastic modulus of pharmaceutical materials affects a number of pharmaceutical processes and subsequently formulation performance and is currently assessed by bulk methods, such as beam bending of compacts. Here we demonstrate the accurate measurement of the elastic modulus of alpha monohydrate lactose from the dominant (011) face of single crystals using atomic force microscopy (AFM) as 3.45+/-0.90GPa. The criteria to ensure this data is recorded within the elastic limit and can be modelled using Hertzian theory are established. We compare and contrast this AFM method to a permanent indentation technique based upon a much larger Berkovich pyramidal indenter on a lactose compact and the wider literature. Finally the AFM was utilized to study the elastic response of amorphous lactose, demonstrating that the physical state of the amorphous material changes under repeated loading and behaves in a more crystalline manner under repeated force measurements, suggesting a pressure induced phase transition. The AFM based approach demonstrated has the significant advantages of requiring minimal sample, no need for producing a compact, being non-destructive in that no permanent indent is required and providing a technique capable of detecting variations in material properties across a single particle or a number of particles.

Chemistry, Pharmaceutical↗
PubMed2005

Acetate production from lactose by Clostridium thermolacticum and hydrogen-scavenging microorganisms in continuous culture--effect of hydrogen partial pressure.

The effect of the addition of hydrogen-consuming microorganisms on the metabolism of Clostridium thermolacticum was studied. By growing this bacterium in continuous culture at 58 degrees C, on 29 mmol lactose l(-1) (10 gl(-1)) in the feed, with the H2-consuming microorganisms Methanothermobacter thermoautotrophicus and Moorella thermoautotrophica, the volumetric productivity of acetate was increased up to 3.9 mmol l(-1)h(-1) at a dilution rate of 0.058 h(-1). This was about three times higher than the maximal acetate volumetric productivity quantified when C. thermolacticum was cultivated alone. In the consortium, C. thermolacticum was the only species able to metabolize lactose; it produced not only acetate, but also hydrogen, carbon dioxide and lactate. The other species of the consortium were growing on these by-products. Meth. thermoautotrophicus played an important role as a very efficient hydrogen scavenger and decreased the hydrogen partial pressure drastically: hydrogen was converted to methane. Moor. thermoautotrophica converted lactate as well as hydrogen and carbon dioxide into acetate. As a consequence, lactose was efficiently consumed and the only organic product in the liquid phase was acetate.

Acetates↗
PubMed2004

Lactose-conjugated polyion complex micelles incorporating plasmid DNA as a targetable gene vector system: their preparation and gene transfecting efficiency against cultured HepG2 cells.

alpha-Lactosyl-poly(ethylene glycol)-poly(2-(dimethylamino)ethyl methacrylate) block copolymer (lactose-PEG-PAMA) was synthesized to construct a PIC micellar-type gene vector potentially useful for selective transfection of hepatic cells. Lactose-PEG-PAMA spontaneously formed a polyion complex (PIC) micelle with plasmid DNA (pDNA) encoding luciferase (pGL3-Luc) in aqueous solution without any precipitate formation. The lactosylated PIC micelle thus prepared achieved substantially higher transfection efficiency compared to the control PIC micelle without lactose moieties against HepG2 cells possessing asialoglycoprotein (ASGP) receptors recognizing the beta-d-galactose residue. This pronounced transfection efficacy of the lactosylated PIC micelle was inhibited by the addition of excess asialofetuin (ASF), a natural ligand against the ASGP receptor, indicating ASGP receptor-mediated endocytosis to be a major route of the cellular uptake of the lactosylated micelles. Notably, the lactosylated PIC micelle revealed enhanced transfection compared to the control PIC micelle at a lower dose of pDNA, demonstrating the feasibility of using the ligand-conjugated PIC micellar vector for gene delivery to targeted cells.

Cell Line, Tumor↗
PubMed2005

Release of indomethacin from ultrasound dry granules containing lactose-based excipients.

Physical mixtures were prepared containing indomethacin and beta-lactose and alpha-lactose-based excipients (Ludipress and Cellactose). The mixtures were compacted with the aid of ultrasound, obtaining tablets, which were milled and sieved. Granules thus obtained were examined by optical microscopy and differential scanning calorimetry. The intense yellow color of the granules and the absence of indomethacin peak in thermograms suggest important modifications of indomethacin physical state; the drug thus modified appears to be spread on the excipient particle surface as a thin film, giving a lustrous appearance. No influence of ultrasound was observed on phase transition concerning lactose; only loss of water was important under high energy ultrasound. Dissolution profiles suggest an increased release of the drug from the systems treated with ultrasound at high energy, with respect to a traditional compaction; while no difference could be evidenced among the three excipients that, however, appear all suitable for this ultrasound-aided direct compression process.

Drug Industry↗
PubMed2005

Functional interactions between the subunits of the lactose transporter from Streptococcus thermophilus.

Although the quaternary state has been assessed in detail for only a few members of the major facilitator superfamily (MFS), it is clear that multiple oligomeric states are represented within the MFS. One of its members, the lactose transporter LacS from Streptococcus thermophilus assumes a dimeric structure in the membrane and in vitro analysis showed functional interactions between both subunits when proton motive force ((Delta)p)-driven transport was assayed. To study the interactions in further detail, a covalent dimer was constructed consisting of in tandem fused LacS subunits. These covalent dimers, composed of active and completely inactive subunits, were expressed in Escherichia coli, and initial rates of (Delta)p-driven lactose uptake and lactose counterflow were determined. We now show that also in vivo, both subunits interact functionally; that is, partial complementation of the inactive subunit was observed for both transport modes. Thus, both subunits interact functionally in (Delta)p-driven uptake and in counterflow transport. In addition, analysis of in tandem fused LacS subunits containing one regulatory LacS-IIA domain showed that regulation is primarily an intramolecular event.

Aspartic Acid↗
PubMed2000

Isothermal and non-isothermal crystallization in amorphous sucrose and lactose at low moisture contents.

Differential scanning calorimetry has been used in isothermal and non-isothermal modes to provide information on the crystallization of sucrose and lactose at low water contents. Using approaches previously applied to polymer crystallization an attempt has been made to combine the isothermal and non-isothermal data into a single curve. This is achieved by the use of appropriate shift factors in the time and temperature domains. This was successful for sucrose but not for lactose. It was suggested that this was because lactose crystallizes into multiple forms whereas sucrose crystallizes in a single form.

Calorimetry, Differential Scanning↗
PubMed2001

Inhibition of beta-glycosidases by acarbose analogues containing cellobiose and lactose structures.

Acarbose analogues, containing cellobiose and lactose structures, were prepared by reaction of the two disaccharides with acarbose and Bacillus stearothermophilus maltogenic amylase. The kinetics for the inhibition by the two analogues was studied for beta-glucosidase, beta-galactosidase, cyclomaltodextrin glucanosyltransferase (CGTase), and alpha-glucosidase. Both analogues were potent competitive inhibitors for beta-glucosidase, with K(I) values in the range of 0.04-2.44 microM, and the lactose analogues were good uncompetitive inhibitors for beta-galactosidase, with K(I) values in the range of 159-415 microM, while acarbose was not an inhibitor for either enzyme at 10 and 5 mM, respectively. Both analogues were also potent mixed inhibitors for CGTase, with K(I) values in the range of 0.1-9.3 microM. The lactose analogue was a 6.4-fold better competitive inhibitor for alpha-glucosidase than was acarbose.

Acarbose↗
PubMed1997

A simple access to lactose-derived building blocks required in glycoconjugate synthesis.

Lactose was readily transformed into thexyldimethylsilyl (3,4-O-isopropylidene-beta-D-galactopyranosyl)-(1-->4)-beta- D-glucopyranoside (5); this compound served as intermediate for the generation of partially O-protected lactose building blocks required in oligosaccharide and glycoconjugate synthesis. Thus, from 5 via per-O-benzoylation, desilylation, trichloroacetimidate formation, glycosylation of the Lemieux spacer, and acid-catalyzed de-O-isopropylidenation methoxycarbonyloctyl (2,6-di-O-benzoyl-beta-D-galactopyranosyl)- (1-->4)-2,3,6-tri-O-benzoyl-beta-D-glucopyranoside (12) was obtained. Regioselective benzoylation of 5 with benzoyl cyanide under various conditions afforded 3-O- (13), 2,3,2'-O- (14), 3,2'-O- (16), and 2,2'-O-unprotected (17) lactoside, respectively. De-O-isopropylidenation of 16 gave thexyldimethylsilyl (6-O-benzoyl-beta-D-galactopyranosyl)-(1-->4)-2, 6-di-O-benzoyl-beta-D-glucopyranoside (18), an important 2',3',4'-O-unprotected lactose derivative. Fucosylation of 13 and then de-O-isopropylidenation afforded thexyldimethylsilyl 2,6-di-O-benzoyl-beta-D-galactopyranosyl)-(1-->4)-[(3,4-di-O-acetyl-2-O- benzoyl-alpha-L-fucopyranosyl)-(1-->3)]-2,6-di-O-benzoyl-beta-D- glucopyranoside (21), an important fucosyllactose building block.

Carbohydrate Sequence↗
PubMed1983

Detection of gastric contents in tracheal fluid of infants by lactose assay.

We designed an in vitro assay to detect the presence of lactose in the tracheal aspirates of premature, ventilator-dependent infants. This method was employed to identify recurrent, unrecognized aspiration, which could prolong the requirements for ventilator support and contribute to the development of chronic lung disease. One hundred five determinations of lactose were performed on the tracheal fluid obtained from 42 ventilator-dependent infants who were receiving enteral feedings. There was a wide range of lactose levels (0 to 3,270 nmol lactose/ml tracheal aspirate). Six infants had samples that were highly suggestive of aspiration (greater than 200 nmol lactose/ml tracheal aspirate). Twenty infants had questionably positive samples (25 to 200 nmol lactose/ml tracheal aspirate), and 16 infants had samples that were considered negative for aspiration (less than 25 nmol lactose/ml tracheal aspirate).

Enteral Nutrition↗
PubMed2001

Lactose utilization by Saccharomyces cerevisiae strains expressing Kluyveromyces lactis LAC genes.

Whey generated in cheese manufacture continues being an industrial problem without a satisfactory solution. Genetic modification of the yeast S. cerevisiae to obtain strains able to utilize lactose, is a prerequisite for the utilization of this yeast to convert cheese whey into useful fermentation products (i.e. biomass, heterologous protein and other recombinant products). Although the construction of S. cerevisiae Lac(+) strains has been achieved by different strategies, most of these strains have unsuitable characteristics, such as genetic instability of the Lac phenotype or diauxic growth. In previous communications we have described the construction of genetically stable strains of S. cerevisiae that assimilate lactose with a high efficiency. These strains carry multiple copies of Kluyveromyces lactis LAC4 and LAC12 genes, which code for a beta-galactosidase and a lactose permease, respectively. In this work we report additional results about the effect of gene dosage, and analyze the performance of a selected strain in the bioconversion of cheese whey. Additionally, we describe the construction of a new strain, which combines the Lac(+) phenotype with additional properties of biotechnological interest: flocculence, and the ability to hydrolyze starch.

Cheese↗
PubMed1982

A comparison of the effects of lactose and of two chemically modified waxy maize starches on mineral metabolism in the rat.

Diets containing 30% by weight of waxy maize starch, lactose monohydrate, acetylated distarch phosphate (EEC No. 1414) or acetylated distarch adipate (EEC No. 1422) were fed to weanling female Specified Pathogen-Free Sprague-Dawley rats for 1 yr and to similar 9-month-old rats for 34 wk. Behaviour and general health were unaffected by the different diets and there were no diet-related differences in food consumption. AT the end of the experiment with 9-month-old rats the mean body weight of the animals receiving lactose was significantly lower than that of the controls receiving starch. The animals receiving the modified starches were slightly but not significantly heavier than the controls at the end of both experiments. The main treatment-related changes in rats on the three test diets were (1) caecal enlargement, (2) increased urinary excretion of calcium, (3) increased renal calcification as measured by chemical analysis of renal tissue obtained at autopsy and (4) increased medullary and pelvic nephrocalcinosis as assessed histopathologically. Acetylated distarch adipate had a slightly greater effect on the above parameters than acetylated distarch phosphate but both modified starches had less effect than lactose. The calcium content of the kidneys, as measured by chemical analysis or histopathology, increased with age, even in the animals receiving the control diet. This change may be due to excessively high concentrations of calcium and phosphorus in all the diets, including the control diet. Cortico-medullary mineral deposits were not a feature in these studies possibly because the diets were not deficient in magnesium. The importance of correct dietary formulation in long-term toxicity studies is emphasized.

Animals↗
PubMed1985

[Mechanisms of efflux of a substrate accumulated by the lactose permease of Escherichia coli: theoretical and experimental study].

At the steady-state of accumulation of intracellular lactose by the beta-galactoside permease of Escherichia coli, the rate of efflux of the substrate is equal to its rate of influx. An original experimental method and a mathematical processing of the experimental data are proposed to evaluate the relative involvements of the permease-mediated pathway and of the diffusion component in this efflux. The method consists of inducing the lac operon of the bacteria, and then of removing the inducer and allowing the cells to grow further. The permease content and the membrane surface of diffusion are thus varying independently in such a "de-induction" experiment, along which lactose uptake has been monitored at different times. The analysis of the experimental data show that, under conditions of maximal induction, over 95% of the efflux passes through the energized permease. The relevant parameters of the efflux of lactose have been computed and their values allow the prediction of most classical observations, as well as the prediction, never checked, that under physiological conditions, the higher the external substrate concentration, the higher the permease-mediated efflux, according to a saturation kinetics.

Biological Transport↗
PubMed1997

Lactose synthesis in a monotreme, the echidna (Tachyglossus aculeatus): isolation and amino acid sequence of echidna alpha-lactalbumin.

alpha-Lactalbumin and lysozyme were each isolated from echidna (Tachyglossus aculeatus) milk by gel permeation and ion exchange chromatography. The alpha-lactalbumin modified the action of echidna milk galactosyltransferase to promote the synthesis of lactose but had very little effect on bovine galactosyltransferase. Echidna alpha-lactalbumin is a glycosylated protein with an apparent molecular weight of 20,000 (SDS-PAGE) whose concentration in the milk is very low compared with the concentrations of alpha-lactalbumin in the milk of other species. Its amino acid sequence is more similar to that of another monotreme, the platypus (Ornithorhynchus anatinus), than to the sequences of eutherian or marsupial alpha-lactalbumins. Echidna milk lysozyme, even at high concentrations, did not promote the synthesis of lactose by either echidna or bovine galactosyltransferase. We conclude that lactose synthesis in the echidna occurs by the same mechanism as that found in the platypus and other mammals.

Amino Acid Sequence↗
PubMed2001

Methane and hydrogen exhalation in normal children and in lactose malabsorption.

UNLABELLED: Methane (CH4) and hydrogen (H2) are gases produced in the colon by the breakdown of carbohydrates, due to the action of anaerobic methanogenic bacteria. No papers have been published in pediatrics concerning these gases production and exhalation. Understanding of the pattern of H2, CH4, carbon dioxide (CO2), butyrates, indolellipsis,etc., production and exhalation, which may differ in gastrointestinal diseases, may be helpful as far as the diagnosis and treatment of some gastrointestinal conditions is concerned. Exhalation of H2, CH4 and CO2 by breath air was studied in basal conditions in 338 normal infants and in 27 lactose malabsorbers. Moreover, stools collected and stored for 10-12 h in anaerobic and aerobic conditions were incubated in anaerobiosis at 38 degrees C. After a 4-h incubation period, H2, CH4 and CO2 were determined. RESULTS: Methane production is independent of hydrogen production; the number of children producing CH4 increases from 0% at 12 months of age to 44% at the age of 9 years. In lactose malabsorption, we found 26 children producing increased quantities of H2 and no methane, and only one producing methane but no hydrogen, which proves that methanogenic bacteria are independent of H2-producing bacteria, and that CH4 determination is compulsory in the study of lactose malabsorption. The incubation of stools in an anaerobic milieu at 38 degrees C for 4 h, in an attempt to imitate the human colon, showed a great production of methane and less of H2 in the stools collected and stored in anaerobic conditions. The same incubation method was applied to the stools collected and stored in aerobic conditions: production of H2 and CH4 was much lower than in the collected and stored anaerobic group. The appearance of CH4 in the stools of the aerobic group proves that methanogenic bacteria are, to a small degree, resistant to oxygen. CONCLUSIONS: The study of gas exhalation in pediatrics merits more study by researchers, with a view to defining a special pattern of gas production in pathological conditions. The anaerobic stool incubation method is a good model for studying gas production under the effect of different diets and the gas production pattern in gastrointestinal diseases.

Aerobiosis↗
PubMed2003

Influence of inverse gas chromatography measurement conditions on surface energy parameters of lactose monohydrate.

Surface energy of any powder determined by inverse gas chromatography (IGC) should be independent of the measurement conditions or type of column used. In this study stainless steel and glass columns were filled with lactose powder. Dispersive and polar components of surface free energy were determined at different flow rates of carrier gas using lactose alone or diluted with calcinated diatomite (Chromosorb W). It was found that measurement conditions did not influence the value of the dispersive parameter of surface energy. On the contrary, K(a) and K(d) values were found to be dependent on dilution of lactose with Chromosorb W. The influence of other parameters on the results was found to be much smaller.

Adsorption↗
PubMed2000

The influence of lactose carrier on the content homogeneity and dispersibility of beclomethasone dipropionate from dry powder aerosols.

Dry powder formulations for inhalation usually comprise a mixture of coarse lactose (CL), employed as a carrier, and micronized drug. It was the aim of this study to determine the effects of fine lactose (FL), blended as a tertiary component on the mixing homogeneity and dispersibility of a model hydrophobic drug, beclomethasone dipropionate (BDP). BDP particles (volume median diameter (VMD) 4.6 microm) existed mainly as agglomerates, the majority of which were not dispersed into primary particles after aerosolization at a high shear force (4.7 psi). The resultant particle size distribution of BDP was multi-modal with VMD varying between 4.7 and 30.2 microm. Ternary interactive mixtures were prepared to consist of CL, FL and BDP with a fixed ratio of lactose to BDP of 67.5:1 w/w, but two concentrations of FL, i.e. 2.5 and 5%, w/w. The mixing was carried out using different sequences of adding the three components for two mixing times (15 and 60 min). Binary mixtures composed of CL and BDP were prepared for both mixing times as the controls, and these exhibited a coefficient of variation (COV) in BDP content <= 5%. Addition of FL to the binary formulations greatly reduced the content uniformity of BDP if the final powder were prepared by first mixing CL with FL before mixing with the drug (COV>20%, after mixing for 15 min). However, the mixtures, prepared using other mixing sequences, had a similar uniformity of BDP content to the binary mixtures. All ternary mixtures containing 2.5% FL consistently produced a significantly higher (ANOVA P<0.01) fine particle fraction (FPF, 3.1--6.1%) and fine particle dose (FPD, 13.6--30.1 microg) of BDP than the binary mixtures (FPF, 0.3-0.4%; FPD, 1.6-2.1 microg) after aerosolization at 60 l min(-1) via a Rotahaler into a twin stage liquid impinger. The mixing sequences exerted a significant (P<0.05) effect on the dispersion and deaggregation of BDP from the formulations prepared using a mixing time of 15 min but such an effect disappeared when the mixing time was lengthened to 60 min. The dispersibility of BDP was always higher from the ternary mixtures than from the binary mixtures. BDP delivery from dry powder inhalers was improved markedly by adding FL to the formulation, without substantial reduction in the content uniformity of the drug.

Aerosols↗