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Results for “Lactose Factors”

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At least 19 recordsLinked to original sources
PubMed1975

Isolation of a hybrid F' factor-carrying Escherichia coli lactose region and Salmonella typhimurium histidine region, F42-400 (F' ts114 lac+, his+): its partial characterization and behavior in Salmonella typhimurium.

Episome F' ts114 lac+ (F42-114) was transferred into Salmonella typhimurium carrying an F'his+ (FS400) episome, and fused episome F' ts114 lac+, his+ (F42-400) was obtained. Episome F42-400 could be transferred to S. typhimurium, Escherichia coli and Klebsiella pneumoniae. Identification of the episome was based on: (i) temperature sensitivity of the Lac+ and His+ phenotypes; (ii) the fact that F- segregants, obtained after temperature curing or acridine orange curing, were simultaneously Lac- and His-; and (iii) linkage of lac+ with his+ in episomal transfers to E. coli and S. typhimurium. The frequency of episome transfer was influenced by the genotype of the donor. Plasmid LT2, prevalent in S. typhimurium LT2 strains, was suggested to be responsible for the low fertility of S. typhimurium donors. Episome F42-400 was capable of chromosome mobilization, and the extent of chromosome mobilization was not influenced by the presence or absence of the histidine region on the donor chromosome. Growth in a defined medium with acridine orange was able to cure F42-400. The frequency of curing was increased (the frequency of His+ cells was 0.0001%) if the cells were grown at 40 C in the presence of acridine orange. Selection for temperature-resistant Lac+, His+ derivatives in a strain without histidine deletion yielded Hfr strains. However, similar and stronger selections in strains without the chromosomal histidine region failed to yield Hfr strains. Our inability to obtain Hfr's in strains without the chromosomal histidine region was explained by assuming that the episome F42-400 has lost the F sites involved in integration into the S. typhimurium chromosome.

Acridines↗
PubMed1992

Analysis of tumour necrosis factor alpha-specific, lactose-specific and mistletoe lectin-specific binding sites in human lung carcinomas by labelled ligands.

Receptor sites can be visualized by labelled ligands as an alternative to receptor-specific antibodies, as substantiated for two different receptor classes. Recombinant tumour necrosis factor alpha (TNF) was biotinylated via amino-groups and the resultant probe was applied to formalin-fixed, paraffin-embedded tissue sections of 94 primary bronchial carcinomas and to normal peripheral lung parenchyma. In addition, monoclonal antibodies specific for neuron-specific enolase (NSE) and TNF itself were used. The biotinylated beta-galactoside-specific mistletoe lectin, which exhibits dose-dependent immunomodulatory and toxic potency, and two probes that specifically detect certain types of sugar receptors were employed to illustrate further the feasibility of using ligands for receptor localisation. The tumours comprised 62 small cell lung carcinomas, 10 epidermoid carcinomas, 11 adenocarcinomas and 11 large cell anaplastic carcinomas. Expression of TNF-binding sites was found in 39 of the small cell lung carcinomas and in 13 of the non-small cell lung carcinomas. Binding capacity for the TNF-specific antibody was seen in similar proportions of small cell lung carcinomas and of non-small cell lung carcinomas. None of the normal lung parenchymas revealed significant staining. Binding capacities to mistletoe lectin were seen in all normal lung parenchymas and in nearly all cases of adenocarcinoma (10/11). A correlation between the expression of NSE and the binding capacities to TNF was detected. Endogenous lectins, specific for lactose or beta-GalNAc, were displayed in nearly one half of the small cell lung carcinoma cases (44% or 45% respectively) and in about 25% of the non-small cell lung carcinoma cases.

Acetylgalactosamine↗
PubMed1977

The effect of disaccharides on the plaque-forming potential of Streptoccoccus mutans.

The comparative and combined effects of sucrose, maltose, and lactose as factors on the plaque-forming potential of Streptococcus mutans were assessed. With increasing additions of maltose to sucrose-supplemented medium there was decreasing plaque formation. Lactose additions slightly increased plaque formation, but when combined with maltose they significantly enhanced the maltose inhibition of plaque formation.

Dental Plaque↗
PubMed1990

In vitro expression of Lac-PTS and tagatose 1,6-bisphosphate aldolase genes from Lactococcus lactis subsp. cremoris plasmid pDI-21.

A 4.4-kb EcoR1-EcoR1 DNA fragment from the Lactococcus lactis subsp. cremoris plasmid pDI-21 encoded the tagatose 1,6-bisphosphate (TBP) aldolase gene and the Lac-PTS genes. In vitro transcription-translation using Escherichia coli S30 extract showed the synthesis of 41,000-, 23,000- and 12,000-dalton proteins which correspond to the TBP-aldolase, Lac-PTS enzyme II, and factor III proteins respectively.

Aldehyde-Lyases↗
PubMed1977

Drug migration during drying of tablet granulations I: effect of particle size of major diluent.

Migration of a water-soluble drug, propoxyphene hydrochloride, during drying of tablet granulations was studied. Wet granulations of the drug were prepared using lactose as the major diluent and corn starch as a disintegrant. Particle-size fractions of lactose ranging from 53 to 177 micron in diameter were employed in different granulations to examine the effect of particle size of the major diluent on drug migration. Determination of drug concentration at various depths in a dried granulation bed was accomplished by using a drying cell consisting of four layers. A numerical coefficient of migration was developed to compare the extent of drug migration in the various lactose granulations. Migration increased with decreasing particle size of the major diluent, lactose. Two factors that may contribute to increased migration with smaller particles are increased entry suction due to decreased intragranular capillary size and increased intergranular contact area.

Chemistry, Pharmaceutical↗
PubMedDate not supplied

Lactose intolerance in protein-energy malnutrition: a clinical case study and family study using a hydrogen (H2) breath-analysis test for carbohydrate malabsorption.

A non-invasive, interval sampling hydrogen (H2) breath-analysis test for carbohydrate malabsorption was used in a 3 year-old Guatemalan child with severe protein-energy malnutrition (kwashiorkor) and in this relatives: mother half-sister and step-father to examine genetic and nutritional factors in lactose intolerance in young children. Clinical lactose intolerance was present in the patient on admission, and lactose malabsorption, even of 0.88 g per kg of weight, persisted after complete nutritional recobly due to gastric retention of the substrate. Malabsorption of a physiological dose of lactose, 12.5 g, was detected in the mother and step-father while their daughter exhibited normal growth and development and normal lactose absorption at 8 months of age. The H2 breath test proved to be a sensitive, well-tolerated procedure for both adults and young children. Pitfalls, such as delayed gastric emptying, absence of normal bacterial flora, prior use of antibiotics, must be considered in interpreting H2 breath test results in children.

Adult↗
PubMed1979

Multiple integration sites for the lactose transposon Tn 951 on plasmid RP 1 and establishment of a coordinate system for Tn 951.

Various molecules generated by transposition of the lactose transposon Tn 951 from plasmid pGC1 to plasmid RP1 were examined by DNA heteroduplex and restriction endonuclease analysis. Tn 951 was found to transpose to at least eight different sites on RP 1 in both possible orientations. A coordinate system for the lactose transposon Tn 951 is constructed.

DNA Restriction Enzymes↗
PubMed1978

Amplification of the lactose carrier protein in Escherichia coli using a plasmid vector.

The isolation and properties of a hybrid plasmid carrying the Y gene of the lac operon of Escherichia coli are described. The lactose carrier protein, coded for by the Y gene, is readily identified upon lac operon induction in strains carrying the plasmid. The protein comprises about 15% of the cytoplasmic membrane protein synthesized in the first generation after induction, compared with a wild type strain induced under the same conditions where lactose carrier protein comprises 1.4% of the cytoplasmic membrane protein.

Carrier Proteins↗
PubMed1979

Relief of polarity in E. coli depleted of 30S ribosomal subunits.

Escherichia coli was depleted of ribosomes by a thermal shock at 47 degrees C which quantitatively destroyed the 30S ribosomal subunits. During recovery in minimal medium at 30 degrees C RNA is synthesized while protein synthesis resumes only after about 90 min. It is shown that lac mRNA is synthesized in the complete absence of ribosomal activity and hence RNA synthesis is not coupled to protein synthesis. Lac mRNA from a series of lac nonsense mutants was examined in both heated and untreated cells. It was found that the polar effect of nonsense mutation is relieved in the absence of ribosomes and that this relief is due to the synthesis of larger mRNA molecules. Since Rho remained active in thermally treated cells, premature termination at secondary signals within the lac operon must also depend on the presence of active ribosomes.

Escherichia coli↗
PubMed1979

Synthesis and degradation of lac mRNA in E. coli depleted of 30S ribosomal subunits.

Escherichia coli was depleted of active ribosomes by a thermal shock at 47 degrees C which quantitatively destroyed the 30S ribosomal subunits. During recovery, RNA is synthesized while protein synthesis resumes only after about 90 minutes. It is shown that lac mRNA is synthesized in the complete absence of ribosomal activity and hence RNA synthesis is not coupled to protein synthesis. Transcription time and average transcript length were slightly less than in untreated cells. lac mRNA was degraded much more slowly in bacteria depleted of ribosomes. In E. coli W both functional half life (T 1/2 = 28 min vs. 2.25 in untreated cells) and chemical stability. The analysis of rna and pnp mutants showed that polynucleotide phosphorylase is involved in lac mRNA degradation in heat treated cells but that RNase I is not. The functional T 1/2 was increased in pnp mutants and was 95 min during the recovery period. The rate of chemical decay is so slow that the half-life cannot be accurately determined.

Bacterial Proteins↗