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PubMedDate not supplied

[Phosphatase activity and level of cyclic nucleotides upon implantation of polyurethane with lactose in the main chain].

Activity of hydrolases, acid and alkaline phosphatases (AP and A1P) in connective-tissue capsules as well as the amount of cyclic nucleotides in the rat blood plasma with implantation of polyurethane on the basis of polyoxytetramethylenglycol and 4,4'-diphenylmethane diisocyanate with lactose in the main chain were studied. Data obtained indicate that polyurethane with lactose in the main chain is biocompatible and nontoxic and may be recommended for the purposes of endoprosthesis.

Acid Phosphatase↗
PubMed1990

[Bacteriophage types represented by lactose-fermenting Salmonella agona strains].

Bacteriophage typing was performed on 1911 S. agona, lactose-fermenting strains. These strains were isolated from hospitalised newborns and neonates patients. Out of 1911 strains 98.8% were typable by means of phage set prepared for strains differentiation of Salmonella agona showing typical biochemical properties. It was shown that in 16 provinces from which the strains were obtained in 1983-1985 type V (49.5%) and type XI (25.4%) prevailed. Subtypes VA and VB were distinguished within type V. Altogether 20.3% of strains were classified as belonging to these subtypes. Their lytic reaction was weaker with phages 3, 4, and 9 with the characteristic range of phage type V strains. Among tested strains types I, XIII, and XVI were also represented composing 2, 6, 0, 9, and 0.3% of total number of strains respectively. 1.5% of strains were nontypable and 0.2% showed lytic reactions different from that included in up to now used scheme of typing. It can be concluded that lactose-fermenting S. agona strains show susceptibility to lowered number of phages than typical for Salmonella species strains. It seems that differentiation of this atypical biochemical variant of S. agona with, the use of phage set used up to now may be also usefull in practice as it is the case in respect to strains with typical biochemical properties.

Bacteriophage Typing↗
PubMedDate not supplied

[Leuconostocs in raw milk: isolation and identification of species rapidly utilizing lactose].

Fast lactose fermenting Leuconostoc species and subspecies were isolated from raw milk. Samples were obtained from dairy farms of the surroundings of Buenos Aires city. A lactose, non selective, isolation medium was employed (YCL). Differentiation of leuconostocs from Lactobacillus viridescens and L. confusus was avoided on account of the use of this medium. 801 typical colonies of lactic acid bacteria were selected from YCL agar; 710 of them were identified as lactic acid bacteria from which 114 strains belonged to the genus Leuconostoc. These last strains were then tested for species and subspecies differentiation by dextran production and sugar fermentation. Leuconostoc mesenteroides subsp. dextranicum and L. lactis were identified. Four strains identified as Leuconostoc spp do not belong to any known species.

Animals↗
PubMed1989

A calorimetric and equilibrium investigation of the hydrolysis of lactose.

The thermodynamics of the hydrolysis of lactose to glucose and galactose have been investigated using both high pressure liquid chromatography and heat-conduction microcalorimetry. The reaction was carried out over the temperature range 282-316 K and in 0.1 M sodium acetate buffer at a pH of 5.65 using the enzyme beta-galactosidase to catalyze the reaction. For the process lactose(aq) + H2O(liq) = glucose(aq) + galactose(aq), delta G0 = -8.72 +/- 0.20 kJ.mol-1, K0 = 34 +/- 3, delta H0 = 0.44 +/- 0.11 kJ.mol-1, delta S0 = 30.7 +/- 0.8 J.mol-1.K-1, and delta Cop = 9 +/- 20 J.mol-1.K-1 at 298.15 K. The standard state is the hypothetical ideal solution of unit molality. Thermochemical cycle calculations using enthalpies of combustion and solution, entropies, solubilities, activity coefficients, and apparent molar heat capacities have also been performed. These calculations indicate large discrepancies which are attributable primarily to errors in literature data on the enthalpies of combustion and/or third law entropies of the crystalline forms of the substrates.

Calorimetry↗
PubMed1989

Platelet-aggregation is stimulated by lactose-inhibitable snake venom lectins.

Five lactose-specific lectins from snake venoms were tested for the ability to stimulate the aggregation of human platelets. Three of the lectins, bushmaster (Lachesis muta), cottonmouth (Ancistrodon piscivorous leukostoma) and rattlesnake (Crotalus atrox) lectins, consistently stimulated secretion and aggregation. Thrombolectin (Bothrops atrox) occasionally caused aggregation. Copperhead (Agkistrodon contortrix contortrix) lectin did not by itself cause platelet aggregation. Lactose, a specific inhibitor of hemagglutination mediated by these lectins was a potent inhibitor of lectin-induced aggregation. Antiserum specific for bushmaster lectin inhibited aggregation by bushmaster lectin. In contrast, the same antiserum and anti-cottonmouth lectin serum enhanced aggregation by low levels of the other lectins. A variety of substances were assayed in the aggregometer for the ability to inhibit aggregation in response to these lectins. Both secretion and aggregation were inhibited by PGI2 and PGE1. Furthermore, lectin-induced aggregation was completely blocked by trifluoperazine and partially blocked by indomethacin. Monoclonal antibodies specific for GP IIb/IIIa (AP2, A2A9, LJP5, LJCP8) but not monoclonals directed against other platelet membrane proteins (AP1 and AP3) inhibited lectin-induced aggregation. The peptide Arg-Gly-Asp-Ser but not Arg-Ala-Asp-Ser was a potent inhibitor of aggregation.

Antibodies, Monoclonal↗
PubMed1989

Sorbitol-gelatin and glutamic acid-lactose solutions for stabilization of reference preparations of measles virus.

The work reported here sought to assess the protection afforded by two stabilizing solutions (sorbitol-gelatin and glutamic acid-lactose) in preserving the potency of freeze-dried Schwarz strain measles virus during storage with a view to the production of reference preparations and working lots of virus suspensions. Stabilized virus suspensions and control suspensions were stored at -70 degrees C or were freeze-dried and stored at -20 degrees C, and their potency was determined over a storage period of 21 months. It was found that the sorbitol-gelatin imparted more satisfactory stability (r = +0.18) to the freeze-dried virus suspensions than did the glutamic acid-lactose. The results also indicate that sorbitol-gelatin, used under the conditions of this study, is an effective stabilizer in the preparation of freeze-dried suspensions of Schwarz strain measles virus employed as reference preparation working lots.

Culture Media↗
PubMed1989

Isolation and characterization of lactose permease mutants with an enhanced recognition of maltose and diminished recognition of cellobiose.

In the present study, lactose permease mutants were isolated which have an enhanced recognition toward maltose (an alpha-glucoside) and diminished recognition for cellobiose (a beta-glucoside). Nine mutants were isolated from a strain encoding a wild-type permease (pTE18) and nine from a strain encoding a mutant permease which recognizes maltose (pB15). All 18 mutants were subjected to DNA sequencing, and it was found that all mutations are single base substitutions within the lac Y gene effecting single amino acid substitutions within the protein. From the pTE18 parent, substitutions involved Tyr-236 to Phe or His; Ser-306 to Thr; and six independent mutants in which Ala-389 was changed to Pro. From pB15, Tyr-236 was changed to Phe or Asn, Ser-306 to Thr or Leu, Lys-319 to Asn, and His-322 to Tyr, Asn, or Gln. All 18 mutants exhibited enhanced recognition for maltose (compared with the pTE18 strain) and a diminished recognition for cellobiose. In addition, all mutants showed a diminished recognition toward beta-galactosides as well. The Phe-236, His-236, Leu-306, Asn-319, Tyr-322, Asn-322, and Gln-322 mutants were completely defective in the uphill accumulation of methyl-beta-D-thiogalactopyranoside whereas the Asn-236, Thr-306, and Pro-389 mutants could effectively accumulate methyl-beta-D-thiogalactopyranoside against a concentration gradient. The mutants obtained in this study, together with previous lactose permease mutants, tend to be found on transmembrane segments, and those which are on the same transmembrane segment are often found three or four amino acids away from each other. This pattern is consistent with a protein structure in which important amino acid side chains project from several transmembrane segments in such a way as to form a hydrophilic channel for the recognition and transport of H+ and galactosides. It is proposed that the mechanism for H+/lactose cotransport is consistent with a "flanking gate" model in which the protein contains a single recognition site for galactosides within the channel which is flanked on either side by gates.

Base Sequence↗
PubMed1989

[Consequences of the composition of breast milk for the nutrition of underweight newborn infants. II. Lipids and lactose].

The concentrations of fat, lactose and protein were measured in the 24 hour pooled breast milk of 37 mothers delivering preterm (PTM) and of 19 mothers delivering term (TM) from the second to the eighth postnatal day and in addition in the PTM from the third week of lactation. During the 4th week of life the nitrogen retention, the fat absorption rate as well as the energy balance were estimated in 21 very low birth weight infants appropriate for gestational age fed either native PTM (n = 11) or by heating procedures sterilized PTM (n = 10). The concentrations of fat and lactose increase within in the first week of lactation. The concentrations of fat are higher in the PTM during the first 3 days of lactation which results in a higher energy density of PTM during the first days of lactation. At the end of the first week of lactation there are no differences in the energy density between PTM and TM. The fat absorption rate was significantly lower in the infants fed sterilized PTM than in the infants fed native PTM (70.5 +/- 8.4 vs 86.3 +/- 7.4 p.c.). Thus, an energy intake of (70.5 to 8.4 vs 86.3 +/- 7.4 p.c.). Thus, an energy intake of 120-130 kcal/kg.d or an energy absorption of more than 100 kcal/kg.d; respectively, is possible by feeding native PTM as well as TM when feeding volumes of more than 180 ml/kg.d are tolerated. When sterilized breast milk is used or the feeding volume is below 160 ml/kg.d an energy supplementation of the milk is necessary.(ABSTRACT TRUNCATED AT 250 WORDS)

Breast Feeding↗
PubMed1987

The role of genes LAC1 and LAC2 in the biosynthesis of lactose metabolism enzymes by Kluyveromyces lactis.

By crossing different Kluyveromyces lactis strains, the role of genes LAC1, LAC2 and of gene C were analyzed. These genes are involved in the biosynthesis of enzymes for the metabolism of lactose and galactose. They control the biosynthesis of the lactose and galactose transport, of beta-galactosidase and of the three enzymes of the Leloir pathway. The presence of at least one of the LAC gene is required for the biosynthesis to occur. The gene C seems to code for a negative factor which blocks the expression of the LAC1 and LAC2 genes in the absence of an inducer.

Biological Transport↗
PubMed1988

Comparative evaluation of two direct compression lactose grades for pyridoxine hydrochloride tablets.

Fast flow lactose (FFL) and anhydrous lactose (AHL) were comparatively investigated for the manufacture of pyridoxine hydrochloride tablets. The results showed that drug/FFL formulations possessed better performance. Harder tablets were, however, compressed from AHL blends. Linear relationships which correlate tablet physical properties to excipient concentration in a given formulation were established. Tablet batches formulated with FFL dissolved in shorter times und showed better stability characteristics on aging.

Chemistry, Pharmaceutical↗
PubMed1986

[Effects of lactose ingestion on protein metabolism in the newborn lamb].

Whole body and tissue protein turnovers were measured in 6 newborn lambs taken from their mothers immediately after birth. Three lambs (AJ) were hourly fed 50 ml of saline (NaCl 0.9%), and 3 (AL) were fed, on the same schedule, 50 ml of saline with 2.25 g of lactose added. They were continuously infused L-[4,5(3)H]-leucine for 6 h when they were 2 h 30 min old. Plasma glucose and insulin were higher in AL than in AJ lambs. On the contrary, the lowest plasma levels of free threonine, valine, isoleucine, leucine, phenylalanine, lysine, histidine, serine and alanine occurred in the lactose-fed lambs (table 1). The concentrations of most free amino acids in liver, brain, small intestine and muscle (Longissimus dorsi) were not significantly different (fig. 1). The irreversible loss of plasma leucine did not differ (mean +/- SD : 160 +/- 47 and 156 +/- 11 micro moles/h/kg for AL and AJ lambs, respectively). The leucine catabolic rate was higher in AJ than in AL lambs (22.4 +/- 2.8 vs 17.9 +/- 1.7%). The fractional rates of protein synthesis in the liver, small intestine and brain were not significantly different between AL and AJ lambs; these rates were higher in the muscle, lungs and whole body of the AL lambs (table 2).

Amino Acids↗
PubMed1979

High resolution thermal denaturation analyses of small sequenced DNA restriction fragments containing Escherichia coli lactose genetic control loci.

Differential melting curves are reported for four DNA restriction fragments (789, 301, 203, and 95 base pairs in length) spanning the lactose control region. All but the smallest melt with two or more subtransitions. Maps are proposed which identify the positions of regions of different thermal stability in the sequences. The sizes of regions comprising subtransitions range from 60 to 200 base pairs. An analysis is made of the cooperativity exhibited between regions in the sequence. The effect on the shape of the differential melting curves of Na+ between 10 mM and 0.5 M as well as that of Mg2+ and glycerol has been determined. An 81-bp-long sequence of unusual thermal stability occurs at the lactose promoter. Its TM change, resulting from the above change in salt concentration, is out of step by 1.5 degree C with the neighboring DNA sequence. The potential biological significance of this behavior is discussed.

Base Sequence↗
PubMed1985

[An improved lactose-peptone medium for the cultivation of chlorine-damaged E. coli bacteria].

A description of a casein-soya-lactose broth (CSLB) for the cultivation of chlorine-impaired E. coli bacteria is given. In this liquid medium the recovery rates of chlorine impaired E. coli are superior or at least equal to recovery rates observed when casein-soya-broth (CSB) is used. Differences are regularly seen when lactose-pepton-broth (LPB) according the German Standards (DEV.K6) is used between direct inoculation into a liquid enrichment medium and inoculation into the same medium following membrane filtration are no longer found when CSSL-broth is used instead of LPB.

Chlorine↗
PubMed1977

[Influence of dietary lactose on the development of lactase activity in the digestive tract of the pig].

Lactase activity has been measured in the pancreas, the small and large intestine of 79 pigs varying in age from 6-7 months. The endogenous enzyme level fluctuated along the small intestine but the activity did not vary according to the level of lactose fed in the diet either just after weaning or from 25 to 100 kg of live weight. Measurements performed in the content of the intestine showed that lactose could be digested by the enzymes of the microflora mostly active in the ileum, the caecum and the large intestine.

Animals↗
PubMed1977

Enhanced stability of meningococcal polysaccharide vaccines by using lactose as a menstruum for lyophilization.

A comparison is made between lactose and mannitol as additives for the lyophilization of meningococcal polysaccharide vaccines. From the stability data obtained on storage at high temperatures, it is concluded that vaccines containing lactose as a menstruum for lyophilization are much more stable than vaccines prepared with the currently used additive, mannitol. The enhanced stability of these vaccines makes it possible to store also group A vaccines at 5 degrees C instead of at -20 degrees C, and to use them in places without freezing facilities.

Bacterial Vaccines↗
PubMed1979

Infrared estimation of fat, protein, and lactose in milk: evaluation of multispec instrument.

Thirty-eight milks (including homogenized and unhomogenized herd milks, individual cow milks, and packaged milks) were pre-analyzed by accepted standard methods and then analyzed in duplicate with a Multispec instrument on 2 different days. For the combined data, mean differences between duplicates were 0.01% or less within days and 0.025% or less between days. Standard deviations of difference between duplicates were 0.02% or less. Overall mean differences between Multispec and standard results were 0.02% or less with standard deviations of difference of 0.041%, but means for protein in packaged milks were 0.038% lower and means for lactose in individual cow milks were 0.04% higher than standards. Standard deviations of difference for fat were lower (0.016%) than average for packaged milks and higher (0.06%) than average for individual cow milks. Differences between Multispec results for homogenized and unhomogenized samples of the same herd milks were small, averaging 0.013% for fat, 0.005% for protein, and 0.011% for lactose. Regression equations for the combined data gave standard errors of estimate of about the same magnitude as the standard deviations of difference. Single calibrations would give good estimates for all of the types of milk analyzed, but for best accuracy the instrument should be calibrated with the type of milk to be analyzed.

Animals↗
PubMed1980

Lactose intolerance in adults in Senegal.

The isolated malabsorption of the lactose in the adult is an hereditary feature while is not found often in the white people but is spread out in black Africa. In Senegal, a ratio of about 29% is verified, changing according to the ethnic composition. Only the Peuhls, of semitic origin, show a full tolerance to lactose.

Adult↗
PubMed1984

Bronchospasm induced by vanillin and lactose.

Bronchospasm caused by vanillin and lactose was detected in controlled double-blind challenge tests in an asthmatic patient. It is recommended that all flavouring agents and dyes should be removed from drugs. Lactose is not a suitable placebo for challenges in asthmatic patients. A better choice is cellulose, which is not resorbed by man.

Benzaldehydes↗