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Lactose
Kinds of Lactose Terms modified by Lactose Selected AbstractsMilk sugars and minerals as ingredientsINTERNATIONAL JOURNAL OF DAIRY TECHNOLOGY, Issue 2 2001Matti Harju Lactose is the natural carbohydrate source and prebiotic compound found in the milk of mammals, but large variations in lactase activity in the small intestines of adult populations can cause problems with its use. The value of lactose can be increased by hydrolysis, but even more valuable products can be made by changing the structure of lactose and preventing its absorption in the gut. Some of these nonabsorbable lactose derivatives are already used in medical and functional food applications. Calcium phosphate precipitation to the heat-transfer surfaces is one of the oldest problems of the dairy industry, but if precipitation is carried out in controlled conditions, the precipitate can be further processed to form milk calcium powder. Milk calcium can be used as a natural source of calcium in calcium-fortified dairy products. The mineral and salty taste of whey has reduced its use as a food ingredient. The use of modern membrane technology offers a means of producing whey salt as a by-product of whey demineralization. These otherwise wasted minerals can then be used as a natural mineral salt. Especially interesting is the possibility of recycling the whey salt into cheese, improving its nutritional status. [source] State transitions and physicochemical aspects of cryoprotection and stabilization in freeze-drying of Lactobacillus rhamnosus GG (LGG)JOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2008K.S. Pehkonen Abstract Aims:, The frozen and dehydrated state transitions of lactose and trehalose were determined and studied as factors affecting the stability of probiotic bacteria to understand physicochemical aspects of protection against freezing and dehydration of probiotic cultures. Methods and Results:,Lactobacillus rhamnosus GG was frozen (,22 or ,43°C), freeze-dried and stored under controlled water vapour pressure (0%, 11%, 23% and 33% relative vapour pressure) conditions. Lactose, trehalose and their mixture (1 : 1) were used as protective media. These systems were confirmed to exhibit relatively similar state transition and water plasticization behaviour in freeze-concentrated and dehydrated states as determined by differential scanning calorimetry. Ice formation and dehydrated materials were studied using cold-stage microscopy and scanning electron microscopy. Trehalose and lactose,trehalose gave the most effective protection of cell viability as observed from colony forming units after freezing, dehydration and storage. Enhanced cell viability was observed when the freezing temperature was ,43°C. Conclusions:, State transitions of protective media affect ice formation and cell viability in freeze-drying and storage. Formation of a maximally freeze-concentrated matrix with entrapped microbial cells is essential in freezing prior to freeze-drying. Freeze-drying must retain a solid amorphous state of protectant matrices. Freeze-dried matrices contain cells entrapped in the protective matrices in the freezing process. The retention of viability during storage seems to be controlled by water plasticization of the protectant matrix and possibly interactions of water with the dehydrated cells. Highest cell viability was obtained in glassy protective media. Significance and Impact of the Study:, This study shows that physicochemical properties of protective media affect the stability of dehydrated cultures. Trehalose and lactose may be used in combination, which is particularly important for the stabilization of probiotic bacteria in dairy systems. [source] Biotransformation of Isoflavone Glycosides by Bifidobacterium animalis in Soymilk Supplemented with Skim Milk PowderJOURNAL OF FOOD SCIENCE, Issue 8 2007T.T. Pham ABSTRACT:, Two probiotic strains, Bifidobacterium animalis A and B, were used for the biotransformation of isoflavone glycosides in soymilk prepared from soy protein isolate (SPI) supplemented with skim milk powder (SMP) (SSMP). Unsupplemented soymilk (USM) and reconstituted skim milk powder (RSMP) were used as controls. The numbers of viable microorganisms in these products were enumerated. Lactose and isoflavone contents were quantified using high-performance liquid chromatography (HPLC). Our results showed that there was significantly higher biotransformation of isoflavone glycosides to aglycones in SSMP than that in USM. The levels of biotransformation were 83.96% and 85.43% for B. animalis A and B, respectively, compared to 74.30% and 72.82% for the USM. In addition, lactose utilization by both strains in SSMP was also higher than that in RSMP. At 24 h, 21.16 mg/mL of lactose was utilized in SSMP by B. animalis A compared with that of 16.88 mg/mL in RSMP. Consequently, the pH of SSMP was lower (3.80) than RSMP (4.00). However, the number of viable bacteria in SSMP was slightly lower than that in RSMP but significantly higher than that in USM. It appears that SMP enhanced the biotransformation of isoflavone glycosides to aglycones and SPI increased the lactose utilization by B. animalis A and B. [source] Crystallization Kinetics and X-ray Diffraction of Crystals Formed in Amorphous Lactose, Trehalose, and Lactose/Trehalose MixturesJOURNAL OF FOOD SCIENCE, Issue 5 2005Song Miao ABSTRACT: Effects of storage time and relative humidity on crystallization kinetics and crystal forms produced from freeze-dried amorphous lactose, trehalose, and a lactose/trehalose mixture were compared. Samples were exposed to 4 different relative water vapor pressure (RVP) (44.1%, 54.5%, 65.6%, 76.1%) environments at room temperature. 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 humidity. Lactose crystallized as ,-lactose monohydrate, ,-anhydrous, and anhydrous forms of ,- and ,-lactose in molar ratios of 5:3 and 4:1 in lactose and lactose/trehalose systems. Trehalose seemed to crystallize as a mixture of trehalose dihydrate and anhydrate in trehalose and lactose/trehalose systems. The crystal forms in a mixture of lactose and trehalose did not seem to be affected by the component sugars, but crystallization of the component sugars was delayed. Time-dependent crystallization of lactose and trehalose in the lactose-trehalose mixture could be modeled using the Avrami equation. The results indicated that crystallization data are important in modeling of crystallization phenomena and predicting stability of lactose and trehalose-containing food and pharmaceutical materials. Keywords: crystallization, lactose, trehalose, crystal form, X-ray diffraction [source] Crystallization Kinetics of Amorphous Lactose as a Function of Moisture Content Using Isothermal Differential Scanning CalorimetryJOURNAL OF FOOD SCIENCE, Issue 2 2000C. J. Kedward ABSTRACT: Isothermal differential scanning calorimetry (DSC) was used to study the crystallization kinetics of amorphous lactose at 3 moisture contents. Each sample was heated to several temperatures between Tg and Tm. After subtraction of an induction time, the Avrami equation was used to model the data and a Lauritzen-Hoffman like expression used to fit the crystallization rates between Tg and Tm. The highest Tm/Tg ratio and crystallization rate were observed for the sample containing the most moisture. Conversely the lowest Tm/Tg ratio and crystallization rate were observed for the sample containing the least moisture. Evidence for multiple transitions was seen. The Avrami equation may not be the best way to model such data. [source] Primary microparticles and agglomerates of morphine for nasal insufflationJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 12 2006Paola Russo Abstract The aim of this work was to study the characteristics of powders of morphine HCl suitable for nasal administration to be employed for pain treatment as alternative to injection. Primary microparticles of morphine were prepared by spray drying of aqueous drug solutions using sugars or sugar derivatives as drying protectors and particle shapers. The spray drying procedure modified morphine crystallinity making the substance amorphous and affecting its stability in dependence on the excipient employed. A tendency of the spray-dried powders to turn to varying degrees of yellow was observed. Tumbling the powder in a rotating pan allowed the agglomeration of the primary microparticles. Agglomerates were also obtained by tumbling a mixture of morphine crystals and spray-dried microparticles of excipients, with advantages for the stability of the preparation. A nasal device quantitatively insufflated all the morphine agglomerates. The in vitro transport of morphine through rabbit nasal mucosa was faster using nasal powders than with the saturated solution of morphine. Lactose was the most effective excipient for agglomerate manufacturing and delivery of spray-dried morphine. The agglomerates of morphine crystals mixed with mannitol/lecithin microparticles showed superior stability. However, the drug permeation through rabbit mucosa was slower than with spray-dried morphine microparticle agglomerates. © 2006 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 95:2553,2561, 2006 [source] Triboelectrification of Spray-dried Lactose Prepared from Different Feedstock ConcentrationsJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 1 2000ORLA E. CASSIDY Powder systems may acquire electrostatic charge during various pharmaceutical processing operations and may give rise to difficulties in handling and powder flow, mainly due to adhesion/cohesion effects. We have investigated the electrostatic charging of spray-dried lactose prepared from different feedstock concentrations using a laboratory spray-dryer. Triboelectrification of the spray-dried lactose samples was effected through contact with the stainless steel surface of either a mixing vessel or a cyclone separator. Results from both techniques showed differences in charge accumulation and particle-steel adhesion between the spray-dried lactose samples. As the feedstock concentration used to produce the spray-dried lactose was increased in the range 10,50% w/v, the mean charge on the lactose decreased from ,20.8 to ,1.3 nC g,1 and ,54.9 to ,4.1 nC g,1 for the mixing vessel and cyclone separator, respectively, with a corresponding decrease in adhesion. In addition, as the feedstock concentration was increased from 10 to 50% w/v, decreases were obtained in surface area values (1.06 to 0.56 m2 g,1), pore diameter (198.7 to 83.5 ,m) and pore volume (1.09 to 0.75 cm3 g,1), and together with differences in crystal form correlated with the charge and adhesion results. The results suggested that the feedstock concentration could have a considerable influence on the charging and adhesional properties of spray-dried lactose. This may have relevance during pharmaceutical processing and manufacturing operations. [source] Lactose in drugs: avoided or allowed to lactose maldigesters?ALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 8 2010M. Montalto No abstract is available for this article. [source] Lactose in drugs: avoided or allowed to lactose maldigesters? authors' replyALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 8 2010P. Eadala No abstract is available for this article. [source] Quantifying the ,hidden' lactose in drugs used for the treatment of gastrointestinal conditionsALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 6 2009P. EADALA Summary Background, Lactose intolerance affects 70% of the world population and may result in abdominal and systemic symptoms. Treatment focuses predominantly on the dietary restriction of food products containing lactose. Lactose is the most common form of excipient used in drug formulations and may be overlooked when advising these patients. Aim, To identify and quantify the amount of lactose in medications used for the treatment of gastrointestinal disorders and to identify ,lactose-free' preparations. Methods, Medications used for the treatment of gastrointestinal disorders were identified from the British National Formulary (BNF). Their formulation including excipients was obtained from the Medicines Compendium. The lactose content and quantity in selected medications was measured using high-performance liquid chromatography (HPLC). Results, A wide range of medications prescribed for the treatment of gastrointestinal conditions contain lactose. We have quantified the lactose content in a selection of medications using HPLC. Lactose is present in amounts that may contribute towards symptoms. Lactose-free alternatives were also identified. Conclusions, Lactose is present in a range of medications and may contribute towards symptoms. This may not be recognized by the prescribing doctor as excipients are not listed in the BNF, and the quantity of lactose is not listed on the label or in the accompanying manufacturer's leaflet. [source] Review article: lactose intolerance in clinical practice , myths and realitiesALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 2 2008M. C. E. LOMER Summary Background, Approximately 70% of the world population has hypolactasia, which often remains undiagnosed and has the potential to cause some morbidity. However, not everyone has lactose intolerance, as several nutritional and genetic factors influence tolerance. Aims, To review current clinical practice and identify published literature on the management of lactose intolerance. Methods, PubMed was searched using the terms lactose, lactase and diet to find original research and reviews. Relevant articles and clinical experience provided the basis for this review. Results, Lactose is found only in mammalian milk and is hydrolysed by lactase in the small intestine. The lactase gene has recently been identified. ,Wild-type' is characterized by lactase nonpersistence, often leading to lactose intolerance. Two genetic polymorphisms responsible for persistence have been identified, with their distribution concentrated in north Europeans. Symptoms of lactose intolerance include abdominal pain, bloating, flatulence and diarrhoea. Diagnosis is most commonly by the lactose hydrogen breath test. However, most people with hypolactasia, if given appropriate advice, can tolerate some lactose-containing foods without symptoms. Conclusion, In clinical practice, some people with lactose intolerance can consume milk and dairy foods without developing symptoms, whereas others will need lactose restriction. [source] The galactokinase of Hypocrea jecorina is essential for cellulase induction by lactose but dispensable for growth on d -galactoseMOLECULAR MICROBIOLOGY, Issue 4 2004Bernhard Seiboth Summary Lactose is the only soluble carbon source which can be used economically for the production of cellulases or heterologous proteins under cellulase expression signals by Hypocrea jecorina (=Trichoderma reesei). Towards an understanding of lactose metabolism and its role in cellulase formation, we have cloned and characterized the gal1 (galactokinase) gene of H. jecorina, which catalyses the first step in d -galactose catabolism. It exhibits a calculated Mr of 57 kDa, and shows moderate identity (about 40%) to its putative homologues of Saccharomyces cerevisiae and Kluyveromyces lactis. Gal1 is a member of the GHMP family, shows conservation of a Gly/Ser rich region involved in ATP binding and of amino acids (Arg 51, Glu 57, Asp 60, Asp 214, Tyr 270) responsible for galactose binding. A single transcript was formed constitutively during the rapid growth phase on all carbon sources investigated and accumulated to about twice this level during growth on d -galactose, l -arabinose and their corresponding polyols. Deletion of gal1 reduces growth on d -galactose but does only slightly affect growth on lactose. This is the result of the operation of a second pathway for d -galactose catabolism, which involves galactitol as an intermediate, and whose transient concentration is strongly enhanced in the delta- gal1 strain. In this pathway, galactitol is catabolised by the lad1 -encoded l -arabinitol-4-dehydrogenase, because a gal1/lad1 double delta-mutant failed to grow on d -galactose. In the delta- gal1 strain, induction of the Leloir pathway gene gal7 (encoding galactose-1-phosphate uridylyltransferase) by d -galactose, but not by l -arabinose, is impaired. Induction of cellulase gene expression by lactose is also impaired in a gal1 deleted strain, whereas their induction by sophorose (the putative cellulose-derived inducer) was shown to be normal, thus demonstrating that galactokinase is a key enzyme for cellulase induction during growth on lactose, and that induction by lactose and sophorose involves different mechanisms. [source] Biomimetic modification of chitosan with covalently grafted lactose and blended heparin for improvement of in vitro cellular interactionPOLYMERS FOR ADVANCED TECHNOLOGIES, Issue 1 2008Huaping Tan Abstract Lactose- and heparin-modified chitosan films were prepared and their physical and biological properties were compared with chitosan, chitosan-g-heparin, and chitosan-g-lactose films. Atomic force microscopy (AFM) measurement showed that all these films in the dry state were rather flat with a roughness smaller than 20,nm. While the chitosan-g-lactose/heparin and chitosan-g-lactose films have the highest swelling and weight loss ratios, the chitosan and chitosan-g-heparin films have the lowest. The chitosan-g-lactose/heparin film showed stronger ability to induce chondrocyte attachment, proliferation, viability, and glycosaminoglycan (GAG) secretion than that of the chitosan, chitosan-g-heparin, and chitosan-g-lactose films. Chondrocyte aggregates and nodules were observed on the chitosan-g-lactose/heparin and chitosan-g-lactose films, which still preserved viable metabolic ability. These results show that the lactose-modified and heparin-incorporated chitosan film can enhance the cell,biomaterial interaction synchronously. The resulting chitosan-g-lactose/heparin material is more bioactive that might be applicable as promising scaffold for chondrogenesis. Copyright © 2007 John Wiley & Sons, Ltd. [source] Enzyme-Responsive Controlled Release Using Mesoporous Silica Supports Capped with Lactose,ANGEWANDTE CHEMIE, Issue 32 2009Andrea Bernardos Gesprengte Ketten: Ein biogesteuertes Pfortenmaterial entstand durch Aufpfropfen eines Lactosederivats auf die Porenausgänge eines mesoporösen Trägers. Die Galactosidase-induzierte Hydrolyse der ,1,4-glycosidischen Bindung der Lactose-Einheit (roter Rahmen im Bild) führt zur Freisetzung eines in den Poren des Hybridmaterials eingeschlossenen Farbstoffs in die umgebende Lösung. [source] Effects of carbon sources on fungal morphology and lovastatin biosynthesis by submerged cultivation of Aspergillus terreusASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2009Zhihua Jia Abstract The influences of various carbon sources on fungal morphological changes and lovastatin production were investigated in submerged cultivation of a mutant of Aspergillus terreus. Lactose produced the least biomass (2.3 ± 0.15 gDCW l,1); however, the highest maximal specific lovastatin productivity (,max) was obtained. Glycerol achieved the highest lovastatin titer (937.5 ± 12.5 mg l,1), while soluble starch resulted in the highest biomass (12.05 ± 0.05 gDCW l,1) and the second highest lovastatin titer (501.3 ± 23.4 mg l,1). With the carbon source turning to be more easily metabolized, the values of ,max dropped gradually while the corresponding Dp and mean filament ratio rose tardily. The value of ,max (19.8 mg gDCW,1 d,1) was obtained in the presence of lactose while glucose resulted in the least ,max (3.0 mg gDCW,1 d,1). This led to a 6.6-fold decrease. The corresponding Dp and mean filament ratios appeared to reverse the effects, thus producing 1.9 and 3.3-fold increases, respectively. The slowly utilizable carbon sources regulated the lovastatin production through both the inducement of fungal morphology differentiation and the control of metabolic regulation. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Geschichte und Evolution der Lactose(in)toleranz.BIOLOGIE IN UNSERER ZEIT (BIUZ), Issue 6 2009Das Erbe der frühen Viehzüchter Abstract Die Fähigkeit, auch im Erwachsenenalter noch Lactose verarbeiten zu können, basiert auf Punktmutationen in einem dem Lactase-(LPH-)Gen vorgelagerten Sequenzbereich, der Bindestellen für Regulatorproteine enthält. Die Ursache für die weltweit sehr uneinheitliche Verteilung der Lactase-Persistenz liegt in der europäischen Menschheitsgeschichte: Im Verlauf des 8. vorchristlichen Jahrtausends entwickelte sich im Nahen Osten innerhalb einer größtenteils lactoseintoleranten Population eine Tradition der Milchviehzucht und des Milchverzehrs. Durch den starken Selektionsdruck auf die Lactosetoleranz verbreiteten sich die mutierten Allele sehr schnell. Während des 7. Jahrtausends v. Chr. begannen etliche dieser Populationen sukzessiv Europa zu besiedeln. Auch im nordöstlichen Afrika und auf der arabischen Halbinsel entstand eine Milchwirtschaft, die jedoch auf anderen Mutationen basiert. The ability to digest lactose in adulthood is baised on point mutations within an upstream region of the lactase-(LPH-)gene. This region contains multiple binding sites for different transcription factors. The heterogenous distribution of the lactase persistence all over the world originates from the European history of humanity: in the course of the eighth millennium BC among a mainly lactose-intolerant population in the Near East evolved a cultural practice of dairy farming and milk consumption. As a result of the strong and positive selection the mutated alleles spread out rapidly. In the course of the seventh millennium BC many of these populations gradually settled Central Europe. The beginning of dairy farming in the north east of the African continent and on the Arabian Peninsula are based upon different point mutations. [source] Vorschau auf Heft 6/2009BIOLOGIE IN UNSERER ZEIT (BIUZ), Issue 5 2009Article first published online: 15 OCT 200 Im nächsten Heft: Lactose(in)toleranz Der Zebrafisch als Modellsystem Über die Liebe oder , warum sind Tupajas so wählerisch? Von Neuronen und Netzwerken [source] Immobilization of ,-Galactosidase on Fibrous Matrix by Polyethyleneimine for Production of Galacto-Oligosaccharides from LactoseBIOTECHNOLOGY PROGRESS, Issue 2 2002Nedim Albayrak The production of galacto-oligosaccharides (GOS) from lactose by Aspergillus oryzae ,-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 °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 °C and 21 days at 50 °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 °C. The corresponding reactor productivity was 6 kg/L/h, which is several-hundred-fold higher than those previously reported. [source] Untersuchung der Kristallisation amorpher Lactose in Milchpulver anhand Dynamischer WasserdampfsorptionCHEMIE-INGENIEUR-TECHNIK (CIT), Issue 3 2008W. Danzl Dipl.-Ing. Abstract Milchpulver enthalten Lactose in amorpher Form und sind daher hygroskopisch und instabil. Bei unkontrollierter Kristallisation der amorphen Lactose kann es zu Schwierigkeiten durch Verklumpen oder Bräunungsreaktionen in Milchpulvern oder trockenmilchhaltigen Folgeprodukten kommen. Um die Kristallisationsneigung der amorphen Lactose zu bestimmen, wurden geeignete Methoden anhand dynamischer Wasserdampfsorption (Dynamic Vapour Sorption ,DVS) entwickelt und an Sprühvollmilchpulver demonstriert. [source] Untersuchungen zur Kristallisation von amorphen lactosehaltigen PulvernCHEMIE-INGENIEUR-TECHNIK (CIT), Issue 3 2007A. Ibach Dipl.-Ing. Abstract Bei der Herstellung von Molkepulver und Molkepulvererzeugnissen durch Sprühtrocknung besteht grundsätzlich die Schwierigkeit, dass die im Ausgangskonzentrat enthaltene gelöste Lactose während der raschen Trocknung amorph erstarrt. Amorphe Lactose ist hygroskopisch und instabil, wodurch ihre weitere Verwendung beeinträchtigt wird. Um technisch sinnvolle Prozessbedingungen für mögliche Verfahren zur Umwandlung der amorphen Phase abschätzen zu können, wird die Kristallisation von amorpher Lactose am Beispiel von Lactose-, Molkepermeat- und Molkepulvern mittels der Differential Scanning Calorimetry untersucht. [source] Optimization of process parameters by Taguchi method in the recovery of lactose from whey using sonocrystallizationCRYSTAL RESEARCH AND TECHNOLOGY, Issue 7 2010S. R. Patel Abstract Anti-solvent crystallization of lactose in the presence of ultrasound will reduce crystal size and the level of agglomeration as compared to the commercial cooling crystallization. It offers a potential route to enhance the physical properties as well as the rapid recovery of lactose. Since lactose recovery itself can reduce biological oxygen demand of whey by more then 80%, recovery of lactose from dairy waste stream (whey) solves the problems of dairy industries by improving economics of whey utilization and pollution reduction. In the present study, recovery of lactose from partially deproteinated whey using an anti-solvent (acetone) by sonocrystallization was optimized for finding the most influencing operating parameters; such as sonication time, anti-solvent concentration, initial lactose concentration in the whey and initial pH of sample mixture at three levels using L9 -orthogonal method. The responses were analyzed for recovery of lactose from whey. The anti-solvent concentration and the sonication time were found to be most influencing parameters for the recovery of lactose and the recovery of lactose was found to be 89.03% at the identified optimized level. The crystal size distribution of recovered lactose was found to be narrower (2.5 , 6.5 ,m) as compared to the commercial lactose crystals (3.5 , 9.5 ,m). (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Tagatose, a new antidiabetic and obesity control drugDIABETES OBESITY & METABOLISM, Issue 2 2008Y. Lu A potentially important new drug for treating type 2 diabetes, tagatose, is now in phase 3 clinical trial. The history, development, additional health benefits, mechanisms of action and the potential for the drug are presented in context with a review of the rapidly growing epidemic of type 2 diabetes and treatments for it. An epimer of fructose, the natural hexose tagatose was originally developed by Spherix Incorporated (formerly Biospherics Inc.) as a low-calorie sugar substitute. Only 20% of orally ingested tagatose is fully metabolized, principally in the liver, following a metabolic pathway identical to that of fructose. Following a decade of studies, tagatose became generally recognized as safe for use in foods and beverages under US FDA regulation. The simple sugar is commercially produced by isomerization of galactose, which is prepared from lactose. Early human studies suggested tagatose as a potential antidiabetic drug through its beneficial effects on postprandial hyperglycaemia and hyperinsulinaemia. A subsequent 14-month trial confirmed its potential for treating type 2 diabetes, and tagatose showed promise for inducing weight loss and raising high-density lipoprotein cholesterol, both important to the control of diabetes and constituting benefits independent of the disease. Furthermore, tagatose was shown to be an antioxidant and a prebiotic, both properties cited in the maintenance and promotion of health. No current therapies for type 2 diabetes provide these multiple health benefits. The predominant side effects of tagatose are gastrointestinal disturbances associated with excessive consumption, generally accommodated within 1- to 2-week period. The health and use potentials for tagatose (branded Naturlose® for this use) are given with respect to current type 2 diabetes drugs and markets. Under an FDA-affirmed protocol, Spherix is currently conducting a phase 3 trial to evaluate a placebo-subtracted treatment effect based on a decrease in HbA1c levels. Side effects, contraindications and possibly beneficial new findings will be carefully monitored. It is hoped that early results of the trial may become available by mid-2008. If a subsequent NDA is successful, tagatose may fill a major health need. [source] A Lactulose Bienzyme Biosensor Based on Self-Assembled Monolayer Modified ElectrodesELECTROANALYSIS, Issue 17 2004Susana Campuzano Abstract A bienzyme biosensor in which the enzymes ,-galactosidase (,-Gal), fructose dehydrogenase (FDH), and the mediator tetrathiafulvalene (TTF) were coimmobilized by cross-linking with glutaraldehyde atop a 3-mercaptopropionic acid (MPA) self-assembled monolayer on a gold disk electrode, is reported. The working conditions selected were Eapp=+0.10,V and (25±1),°C. The useful lifetime of one single TTF-,-Gal-FDH-MPA-AuE was surprisingly long, 81,days. A linear calibration plot was obtained for lactulose over the 3.0×10,5,1.0×10,3,mol L,1 concentration range, with a limit of detection of 9.6×10,6,mol L,1. The effect of potential interferents (lactose, glucose, galactose, sucrose, and ascorbic acid) on the biosensor response was evaluated. The behavior of the SAM-based biosensor in flow-injection systems in connection with amperometric detection was tested. The analytical usefulness of the biosensor was evaluated by determining lactulose in a pharmaceutical preparation containing a high lactulose concentration, and in different types of milk. Finally, the analytical characteristics of the TTF-,-Gal-FDH-MPA-AuE are critically compared with those reported for other recent enzymatic determinations of lactulose. [source] Optimization of culture conditions for glucose oxidase production by a Penicillium chrysogenum SRT 19 strainENGINEERING IN LIFE SCIENCES (ELECTRONIC), Issue 1 2010Ragini G. Bodade Abstract The enzyme glucose oxidase (GOD) has been used for a variety of biotechnological applications in food and pharmaceutical industries. In this study, the optimization of extracellular GOD production was carried out in a Penicillium chrysogenum SRT 19 strain isolated from contaminated and decaying cheese samples. Maximum GOD production was attained at pH 6 and 20°C in fermentation broth after 72,h of incubation. The effects of metal ions and sugars were screened for the induction of higher GOD production. The results revealed that glucose and lactose give the highest production of enzyme (0.670 and 0.552,U/mL, respectively) as compared with other sugars (sucrose, cellulose, mannitol and fructose). Out of the seven metal ions studied, CaCO3 (1.123,U/mL) and FeSO4 (0.822,U/mL) act as modulators, while MgSO4 (0.535,U/mL), CuSO4 (0.498,U/mL), HgCl2 (0.476,U/mL), ZnSO4 (0.457,U/mL) and BaSO4 (0.422,U/mL) yield lower production. The study therefore suggests that a strain of P. chrysogenum SRT 19 can be used as a new strain for GOD production. [source] Glucose inhibits the formation of gas vesicles in Haloferax volcanii transformantsENVIRONMENTAL MICROBIOLOGY, Issue 1 2008Torsten Hechler Summary The effect of glucose on the formation of gas vesicles was investigated in Haloferax mediterranei and Hfx.volcanii transformants containing the mc- gvp gene cluster of Hfx. mediterranei (mc-vac transformants). Increasing amounts of glucose in the medium resulted in a successive decrease in the amount of gas vesicles in both species, with a complete inhibition of their formation at glucose concentrations of > 70 mM in mc-vac transformants, and 100 mM in Hfx. mediterranei. Maltose and sucrose imposed a similar inhibitory effect, whereas xylose, arabinose, lactose, pyruvate and 2-deoxy-glucose had no influence on the gas vesicle formation in mc-vac transformants. The activities of the two mc-vac promoters were strongly reduced in mc-vac transformants grown in the presence of > 50 mM glucose. The gas vesicle overproducing ,D transformant (lacking the repressing protein GvpD) also showed a glucose-induced lack of gas vesicles, indicating that GvpD is not involved in the repression. The addition of glucose was useful to block gas vesicle formation at a certain stage during growth, and vice versa, gas vesicle synthesis could be induced when a glucose-grown culture was shifted to medium lacking glucose. Both procedures will enable the investigation of defined stages during gas vesicle formation. [source] The role of colonic metabolism in lactose intoleranceEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 8 2008T. He ABSTRACT Lactose maldigestion and intolerance affect a large part of the world population. The underlying factors of lactose intolerance are not fully understood. In this review, the role of colonic metabolism is discussed, i.e. fermentation of lactose by the colonic microbiota, colonic processing of the fermentation metabolites and how these processes would play a role in the pathophysiology of lactose intolerance. We suggest that the balance between the removal and production rate of osmotic,active components (lactose, and intermediate metabolites, e.g. lactate, succinate, etc.) in the colon is a key factor in the development of symptoms. The involvement of the colon may provide the basis for designing new targeted strategies for dietary and clinical management of lactose intolerance. [source] Lactose intolerance: analysis of underlying factorsEUROPEAN JOURNAL OF CLINICAL INVESTIGATION, Issue 1 2003R. J. Vonk Abstract Background We studied the degree of lactose digestion and orocecal transit time (OCTT) as possible causes for the variability of symptoms of lactose intolerance (LI) in a sample of a population with genetically determined low lactase activity. Methods Lactose digestion index (LDI) was measured by the recently developed 13C-lactose/2H-glucose test. The OCTT was determined using the breath hydrogen test. Based on a 6-h symptom score (SSC) after a challenge dose of 25 g of lactose the subjects were divided into a tolerant group (T: n= 15; SSC = 0) and an intolerant group (IT: n= 28; SSC 1,40). The intolerant group was subdivided according to the severity of symptoms: group ITa (n = 17; mild symptoms without diarrhoea) and group ITb (n = 11; with diarrhoea). Results The LDI was lower in the intolerant group (0·34 ± 0·14) (mean ± SD) than in the tolerant group (0·47 ± 0·14) (P = 0·008). The OCTT of group IT (60, 30,90 min) (median, quartiles) was significantly shorter than that of group T (105, 60,120 min) (P = 0·003) and was positively correlated with the LDI (P = 0·050). In groups ITa and ITb the OCTT (60, 30,90 min; 60, 26,83 min) and LDI (0·30 ± 0·14; 0·39 ± 0·14) were similar. Conclusions Lactose digestion capacity, which is determined by small intestinal lactase activity as well as by OCTT, affects the occurrence of lactose intolerance. However, the major difference in intolerance symptoms is caused by differences in the colonic processing of maldigested lactose. [source] Chemoselective Reagents for Covalent Capture and Display of Glycans in Microarrays,EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 3 2010Emiliano Cló Abstract Glycobiology has made very significant progress in the past decades. However, further progress will significantly depend on the establishment of novel methods for miniaturized, high-throughput analysis of glycan,protein interactions. Robust solid-phase chemical tools and new, chemoselective reagents for biologically meaningful display of surface-immobilized glycans are likely to play a key role. Here we present four new bifunctional linkers that allow highly chemoselective capture of unprotected glycans in solution to form glycan-linker conjugates for direct construction of glycan microarrays (glycochips). The bifunctional linkers carry O -linked aminooxy moieties, some with N -substituents at one end and an amino group at the other. In addition, they contain a substituted benzene ring for UV traceability and improved purification of glycan-linker conjugates. NMR spectroscopic studies in solution proved that N -substituted aminooxy linkers provided model glycan-linker conjugates with the ,-glucopyranoside configuration, i.e. the ring-closed form required for biological recognition. Then an ensemble of glycan-linker conjugates were assembled from mannobiose, lactose, and N -acetyl-lactosamine and used for covalent printing of glycan microarrays. The stability of oximes were studied both in solution and on-chip. In solution, two of the linkers provided glycan-linker conjugates with a remarkable stability at pH 4 or higher, on-chip this relative stability was upheld. Two of the linkers, with different properties, are recommended for the glycobiology toolbox for the construction of glycan microarrays from unprotected glycans. [source] Solution Synthesis of Two Orthogonally Protected Lactosides as Tetravalent Disaccharide-Based ScaffoldsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 13 2004Sergio Castoldi Abstract Two tetravalent lactosidic scaffolds have been synthesised in solution from commercial lactose. Careful manipulation of the protecting groups allowed us to orthogonally protect four OH groups for their use as diversity sites for the development of broad screening libraries of sugar mimics. The selective access to each of these hydroxy groups has been demonstrated on scaffold 2 by deprotection and functionalisation with p -fluorophenyl isocyanate. Finally, the 6-OH derivative of compound 2 was covalently attached to a polymeric support. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Aspergillus nidulans,-galactosidase of glycoside hydrolase family 36 catalyses the formation of ,-galacto-oligosaccharides by transglycosylationFEBS JOURNAL, Issue 17 2010Hiroyuki Nakai The ,-galactosidase from Aspergillus nidulans (AglC) belongs to a phylogenetic cluster containing eukaryotic ,-galactosidases and ,-galacto-oligosaccharide synthases of glycoside hydrolase family 36 (GH36). The recombinant AglC, produced in high yield (0.65 g·L,1 culture) as His-tag fusion in Escherichia coli, catalysed efficient transglycosylation with ,-(1,6) regioselectivity from 40 mm 4-nitrophenol ,- d -galactopyranoside, melibiose or raffinose, resulting in a 37,74% yield of 4-nitrophenol ,- d -Galp -(1,6)- d -Galp, ,- d -Galp -(1,6)-,- d -Galp -(1,6)- d -Glcp and ,- d -Galp -(1,6)-,- d -Galp -(1,6)- d -Glcp -(,1,,2)- d -Fruf (stachyose), respectively. Furthermore, among 10 monosaccharide acceptor candidates (400 mm) and the donor 4-nitrophenol ,- d -galactopyranoside (40 mm), ,-(1,6) linked galactodisaccharides were also obtained with galactose, glucose and mannose in high yields of 39,58%. AglC did not transglycosylate monosaccharides without the 6-hydroxymethyl group, i.e. xylose, l -arabinose, l -fucose and l -rhamnose, or with axial 3-OH, i.e. gulose, allose, altrose and l -rhamnose. Structural modelling using Thermotoga maritima GH36 ,-galactosidase as the template and superimposition of melibiose from the complex with human GH27 ,-galactosidase supported that recognition at subsite +1 in AglC presumably requires a hydrogen bond between 3-OH and Trp358 and a hydrophobic environment around the C-6 hydroxymethyl group. In addition, successful transglycosylation of eight of 10 disaccharides (400 mm), except xylobiose and arabinobiose, indicated broad specificity for interaction with the +2 subsite. AglC thus transferred ,-galactosyl to 6-OH of the terminal residue in the ,-linked melibiose, maltose, trehalose, sucrose and turanose in 6,46% yield and the ,-linked lactose, lactulose and cellobiose in 28,38% yield. The product structures were identified using NMR and ESI-MS and five of the 13 identified products were novel, i.e. ,- d -Galp -(1,6)- d -Manp; ,- d -Galp -(1,6)-,- d -Glcp -(1,4)- d -Glcp; ,- d -Galp -(1,6)-,- d -Galp -(1,4)- d -Fruf; ,- d -Galp -(1,6)- d -Glcp -(,1,,1)- d -Glcp; and ,- d -Galp -(1,6)-,- d -Glcp -(1,3)- d -Fruf. [source] | |||||||||||||||||||||||||||||||||||||||||||