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  • Springer  (200)
  • International Union of Crystallography (IUCr)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Cellular and molecular life sciences 5 (1949), S. 362-364 
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The inhibition of thiouracil goitre in the rat by the methyl ether of vitamin A reported in previous investigations is not to be referred to vitamin A, but to the iodine that is bound to vitamin A in the course of its synthesis. The relation between thiouracil and iodine compounds with different mobility of the iodine: NaI (II), the iodine-containing methyl ether of vitamine A (III), 2:4-dioxo-3:3-diethyl-5-iodine-tetrahydropyridin (IV),N-(4-oxy-3:5-diiodine-benzoyl)-diiodine-DL-tyrosine (V), and 1:4-dioxy-2:3-diiodine-buten-(2) were studied in the thyroid gland of the rat by histological investigation of the degree of development of the thiouracil goitre and by determination of the iodine content of the thyroid. The iodine deprivation caused by thiouracil is definitely inhibited by the iodine compounds named, regardless of the motility of the iodine. The histologically demonstrable thiouracil goitre is likewise inhibited by these compounds, and here the degree of inhibition increases with the motility of the iodine.
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  • 2
    ISSN: 1432-0517
    Keywords: Key words GMO detection ; PCR ; Food labelling ; Quality assurance
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  The detection of genetically modified organisms (GMOs) by the polymerase chain reaction (PCR) is a complex multiparameter problem. Therefore, a number of critical issues in respect to quality control need to be considered. For practical purposes, the PCR process itself can be divided into three subprocesses: template isolation and reaction setup (pre-PCR), PCR reaction and detection of amplification products, and data evaluation (post-PCR). Crucial factors for the pre-PCR process are the following: homogeneity of the sample to be analysed, performance of template isolation and purification in terms of yield and purity, standardized process for the estimation of concentrations of genomic DNA and all reagents used in the reaction. For the PCR itself, crucial factors to be controlled are: setup of reactions, batch to batch variations of reagents, temperature-time programs used for the PCR amplification, and the performance of different types of hardware (e.g. different brands of thermocyclers). The crucial factor for the post-PCR process is the detection of the amplification products of the PCR. The tremendous sensitivity of PCR methods requires a careful and consequent separation of the three processes in terms of hardware, laboratory space and sample handling. The avoidance of contamination is one of the most critical factors. The goal of quality assurance measures must be to ensure appropriate results at maximum sensitivity. The complexity of any PCR system used for the detection of GMOs leads to the requirement of a careful validation process for any laboratory using such methods. For qualitative analyses crucial validation parameters are: specificity, selectivity, repeatability, intermediate precision, reproducibility, limit of detection and robustness.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 48 (1979), S. 325-341 
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The effects of metabolic and respiratory acidosis and alkalosis on cellular calcium metabolism were studied in rat kidney cells dispersed with collagenase. In both types of acidosis, the intracellular pH, total cell calcium, and the cell relative radioactivity after 60 min of labeling are significantly depressed. Kinetic analysis of45Ca desaturation curves shows that acidosis decreases all three cellular calcium pools and depresses calcium fluxes between the superficial and cytosolic pools and between the cytosolic and mitochondrial pools. In alkalosis the intracelluar pH, the total cell calcium, and the cell relative radioactivity are significantly increased. Kinetic studies show that in alkalosis, only the mitochondrial pool is consistently increased. Calcium exchange between the mitochondrial and cytosolic pool is increased in metabolic alkalosis only. These results suggest that hydrogen ion is an important modulator of calcium metabolism, and that the intracellular pH rather than extracellular pH is the critical factor in determining the calcium status of cells during altered acid-base conditions.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    The journal of membrane biology 38 (1978), S. 51-72 
    ISSN: 1432-1424
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The effects of calcium ionophores on cellular calcium metabolism were studied in cultured kidney cells, in cells freshly isolated from rat kidney, and in liver and kidney slices. In isolated cells, these ionophores decreased the total cellular Ca content and the mitochondrial Ca.45Ca efflux from prelabelled cells was also stimulated even in the absence of extracellular Ca. In slices, the ionophore A23187 increased the total slice Ca and the uptake of45Ca. However, the mitochondria isolated from these slices treated with the ionophore had a lower total Ca and a depressed relative radioactivity. These results suggest that the increased cytosolic Ca produced by Ca ionophores may be due to mobilization of intracellular Ca stores rather than to a net shift of Ca from the extracellular fluids to the cell.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Human genetics 〈Berlin〉 82 (1989), S. 289-290 
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Using the polymerase chain reaction, a sequence comprising 400 bp of the human ZFY gene was amplified specifically in the male. The method allows detection of the presence of the ZFY gene in the order of 1:104 cells.
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  • 6
    ISSN: 1432-072X
    Keywords: Bradyrhizobium ; Gene cloning ; Heme ; Marker exchange mutagenesis ; Nitrogen fixation ; Respiration ; Symbiosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Random and site-directed Tn5-induced mutagenesis of Bradyrhizobium japonicum yielded two mutations, one in strain 2960 and the other in strain 2606::Tn5-20, which mapped close to each other but in separate genes. The corresponding wild-type genes were cloned, and their approximate location on the cloned DNA was determined. Mutant 2960 was Fix- and formed green nodules on soybean, whereas strain 2606::Tn5-20 had ca. 4% of wild-type Fix activity and formed white nodules. Cytochrome oxidase assays (Nadi tests) showed a negative reaction with both mutants, indicating a functional deficiency of cytochrome c or its terminal oxidase or both. However, the mutants grew well under aerobic conditions on minimal media with different carbon sources. Furthermore, mutant 2960 had a reduced activity in hydrogen uptake, was unable to grow anaerobically with nitrate as the terminal electron acceptor and 2960-infected soybean nodules contained little, if any, functional leghemoglobin. Southern blot analysis showed that a B. japonicum heme biosynthesis mutant [strain LO505: O'Brian MR, Kirshbom PM, Maier RJ (1987) Proc Natl Acad Sci USA 84: 8390–8393] had its mutation close to the Tn5 insertion site of our mutant 2606::Tn5-20. This finding, combined with the observed phenotypes, suggested that the genes affected in mutants 2960 and 2606::Tn5-20 were involved in some steps of heme biosynthesis thus explaining the pleiotropic respiratory deficiencies of the mutants. Similar to strain LO505, the mutant 2606::Tn5-20 (but not 2960) was defective in the activity of protoporphyrinogen IX oxidase which catalyzes the penultimate step in the heme biosynthesis pathway. This suggests that one of the two cloned genes may code for this enzyme.
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  • 7
    ISSN: 1432-072X
    Keywords: Bradyrhizobium ; Electron microscopy ; Mutants ; Nitrogen fixation ; Nodulation ; Soybean ; Symbiosis ; Transposon Tn5
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The genome of the slow-growing Bradyrhizobium japonicum (strain 110) was mutagenized with transposon Tn5. A total of 1623 kanamycin/streptomycin resistant derivatives were screened in soybean infection tests for nodulation (Nod) and symbiotic nitrogen fixation (Fix). In this report we describe 14 strains possessing a stable, reproducible Nod+Fix- phenotype. These strains were also grown under microaerobic culture conditions to test them for free-living nitrogen fixation activity (Nif). In addition to strains having reduced Fix and Nif activities, there were also strains that had reduced symbiotic Fix activity but were Nif+ ex planta. Analysis of the genomic structure revealed that the majority of the strains had a single Tn5 insertion without any further apparent physical alteration. A few strains had additional insertions (by Tn5 or IS50), or a deletion, or had cointegrated part of the vector used for Tn5 mutagenesis. One of the insertions was found in a known nif gene (nifD) whereas all other mutations seem to affect different, hitherto unknown genes or operons. Several mutant strains had an altered nodulation phenotype, inducing numerous, small, widely distributed nodules. Light and electron microscopy revealed that most of these mutants were defective in different stages of bacteroid development and/or bacteroid persistence. The protein patterns of the mutants were inspected by two-dimensional gel electrophoresis after labelling microaerobic cultures with l-(35S)methionine. Of particular interest were mutants lacking a group of proteins the synthesis of which was known to be under oxygen control. Such strains can be regarded as potential regulatory mutants.
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  • 8
    ISSN: 1432-072X
    Keywords: Methanobacterium thermoautotrophicum ; Bacteriophage ; Methanogenic bacteria ; Plasmid pME2001
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Bacteriophage ψM1, a virulent, oxygen resistant phage of Methanobacterium thermoautotrophicum strain Marburg, was isolated from an anaerobic sludge digester operated at 55°C to 60°C. A reproducible plaque assay and an enrichment procedure for the preparation of high-titer lysates (2x1010 PFU/ml) were established. One-step growth experiments at 62°C showed that the latent period was 4 h and the burst size was 5–6 infective particles per cell. The phage infected Methanobacterium thermoautotrophicum Marburg but none of three other thermophilic representatives of the genus Methanobacterium that were tested. Electron micrographs showed that phage ψM1 has a polyhedral head of 55 nm diameter and a tail of 210 nm in lenght. The ψM1 genome consists of linear double-stranded DNA with a size of 30.4±1.0 kb. Restriction and hybridization analysis of DNA extracted from phage particles revealed two types of linear molecules with the size of the phage genome. About 85% of the DNA molecules in such preparations were genomes of ψM1 whereas approximately 15% were multimers of the cryptic 4.5-kb plasmid pME2001 of the host. ψM1 DNA did not hybridize with chromosomal DNA of Methanobacterium thermoautotrophicum but it exhibited definite homology to total DNA of Methanobacterium wolfei.
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 24 (1983), S. 485-494 
    ISSN: 1432-1041
    Keywords: amiodarone ; pharmacokinetics ; therapeutic serum level ; thyroid function ; antiarrhythmic therapy ; adverse effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In 17 patients on long term therapy with amiodarone, serum drug levels measured by HPLC were related to pharmacological effects. At steady state, serum levels were directly proportional to the dose, 5 mg/kg per day leading to an average serum level of approximately 2.5 µmol/l. The non-amiodarone level of iodine averaged 4-times higher than the level of amiodarone iodine. The elimination half-life of amiodarone ranged from 21 to 78 days, and of non-amiodarone iodine from 24 to 160 days. Control of arrhythmias was satisfactory in all 12 evaluable patients, when the serum amiodarone level exceeded 1.5 µmol/l. Deterioration of vision and polyserositis occurred only at amiodarone levels above 4 µmol/l. Tentatively, a therapeutic range of 1.5 to 4 µmol/l is proposed. In contrast, thyroid dysfunction was observed at any amiodarone level. In view of the narrow therapeutic window, therapy with amiodarone may be optimized by monitoring its serum level and in addition, thyroid function should be regularly checked.
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  • 10
    ISSN: 1432-1041
    Keywords: amiodarone ; desethylamiodarone ; iodine ; pharmacokinetics ; thyroid function ; toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In 23 patients treated with the iodine-containing antiarrhythmic drug amiodarone, the plasma concentrations of amiodarone, desethylamiodarone and iodine have been studied. Besides amiodarone and desethylamiodarone, a pool of iodine-containing substances, NANDAI (non-amiodarone-, non-desethylamiodarone-iodine), was present. At steady state the iodine content of NANDAI amounted to 64% and the iodine content of amiodarone plus desethylamiodarone to 36% of total serum iodine. At steady state 26% of the NANDAI fraction was made up of inorganic iodide, the average plasma concentration of which was at least 40 times above the upper limit of the normal range. The serum elimination half-life of NANDAI of 57–160 days exceeded that of amiodarone (35–68 days) and of desethylamiodarone (31–110 days). At steady state the serum concentration of desethylamiodarone appears to be related to the concentration of amiodarone by a Michaelis-Menten type function, yielding a Km of amiodarone of 2.45 µmol/l and a maximal desethylamiodarone concentration of 3.61 µmol/l.
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