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  • 1
    Electronic Resource
    Electronic Resource
    Threonine diffusion and threonine transport in Corynebacterium glutamicum and their role in threonine production (1996)
    Springer
    Archives of microbiology 165 (1996), S. 48-54 
    Details
    ISSN: 1432-072X
    Keywords: Key words Amino acid transport ; Uptake ; Excretion ; Diffusion ; Threonine ; Corynebacterium glutamicum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Transmembrane threonine fluxes (i.e., uptake, diffusion, and carrier-mediated excretion) all contribut-ing to threonine production by a recombinant strain of Corynebacterium glutamicum, were analyzed and quantitated. A threonine-uptake carrier that transports threonine in symport with sodium ions was identified. Under production conditions (i.e., when internal threonine is high), this uptake system catalyzed predominantly threonine/threonine exchange. Threonine export via the uptake system was excluded. Threonine efflux from the cells was shown to comprise both carrier-mediated excretion and passive diffusion. The latter process was analyzed after inhibition of all carrier-mediated fluxes. Threonine diffusion was found to proceed with a first-order rate constant of 0.003 min–1 or 0.004 μl min–1 (mg dry wt.)–1, which corresponds to a permeability of 8 × 10–10 cm s–1. According to this permeability, less than 10% of the efflux observed under optimal conditions takes place via diffusion, and more than 90% must result from the activity of the excretion carrier. In addition, the excretion carrier was identified by (1) inhibition of its activity by amino acid modifying reagents and (2) its dependence on metabolic energy in the form of the membrane potential. Activity of the excretion system depended on the membrane potential, but not on the presence of sodium ions. Threonine export in antiport against protons is proposed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050295
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  • 2
    Electronic Resource
    Electronic Resource
    Glutamine uptake by a sodium-dependent secondary transport system in Corynebacterium glutamicum (1995)
    Springer
    Archives of microbiology 164 (1995), S. 98-103 
    Details
    ISSN: 1432-072X
    Keywords: Key words Glutamine ; Amino acid transport ; Solute ; uptake ; Corynebacterium glutamicum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Corynebacterium glutamicum took up glutamine by a sodium-dependent secondary transport system. Both the membrane potential and the sodium gradient were driving forces. Glutamine uptake showed Michaelis-Menten kinetics, with a K m of 36 μM and a V max of 12.5 nmol min–1 (mg dry weight)–1 at pH 7. Despite a pH optimum in the alkaline range around pH 9, it was shown that uncharged glutamine is the transported species. The affinity for the cotransported sodium was relatively low; an apparent K m of 1.4 mM was determined. Among various substrates tested, only asparagine, when added in 50-fold excess, led to an inhibition of glutamine transport. It was concluded that glutamine uptake occurs via a specific transport system in symport with at least one sodium ion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050240
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  • 3
    Electronic Resource
    Electronic Resource
    Isolation of the putP gene of Corynebacterium glutamicum and characterization of a low-affinity uptake system for compatible solutes (1997)
    Springer
    Archives of microbiology 168 (1997), S. 143-151 
    Details
    ISSN: 1432-072X
    Keywords: Key wordsCorynebacterium glutamicum ; PutP ; Proline transport ; Compatible solutes ; Osmoregulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Corynebacterium glutamicum accumulates the compatible solutes proline, glycine betaine, and ectoine under conditions of high osmolality. Uptake of proline is mediated by both a high-affinity and a low-affinity secondary transport system. The low-affinity uptake system also accepts glycine betaine and ectoine as substrates. In the present study, the gene encoding the high-affinity proline uptake system PutP was isolated by heterologous complementation of Escherichia coli mutant strain WG389, which lacks the transport systems BetT, PutP, ProP, and ProU and is unable to synthesize proline and glycine betaine. This gene (putP) encodes a protein of 524 amino acids that shares identity with the proline transport systems PutP of E. coli, Staphylococcus aureus, Salmonella typhimurium, Haemophilus influenzae, and Klebsiella pneumoniae. Functional studies of PutP synthesized in E. coli mutant strain MKH13, which also lacks the transport systems for compatible solutes and is unable to synthesize glycine betaine, revealed that this carrier system is not regulated by the external osmolality on the level of activity. K m values of 7.6 mM for proline and 1.3 mM for sodium as cotransported ion were determined. Deletion of the putP gene allowed the functional characterization of another proline uptake system with low affinity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050480
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  • 4
    Electronic Resource
    Electronic Resource
    Testing the “methanochondrion concept”: are nucleotides transported across internal membranes in Methanobacterium thermoautotrophicum? (1987)
    Springer
    Archives of microbiology 146 (1987), S. 370-376 
    Details
    ISSN: 1432-072X
    Keywords: Methanobacterium thermoautotrophicum ; Nucleotide transport ; Nucleotide binding ; Protoplasts ; Membrane vesicles ; Methanochondrion concept
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In order to test the “Methanochondrion concept”, uptake of adenine nucleotides in various membrane preparations of Methanobacterium thermoautotrophicum was studied. The uptake showed properties which are in general interpreted as indicative of a transport mechanism: (i) kinetics in the time range of minutes, (ii) temperature dependence, (iii) substrate specificity and (iv) failure to remove the substrate by extensive washing. However, nucleotide transport as an interpretation of this “uptake” can definitely be excluded. Not only an exchange mechanism of the mitochondrial type, but also a general exchange or an uniport mechanism was ruled out. In contrast, the “nucleotide uptake” was shown to be actually a tight and specific binding of ADP and ATP to binding sites at the interior side of the cell membrane. This was conclusively demonstrated in protoplasts obtained from M. thermoautotrophicum cells. In these protoplasts which do not contain internal membranes also nucleotide binding was observed, but only after disruption of the plasma membrane by osmotic lysis, which leads to the exposure of binding sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00410938
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  • 5
    Electronic Resource
    Electronic Resource
    Urea uptake and urease activity in Corynebacterium glutamicum (1998)
    Springer
    Archives of microbiology 169 (1998), S. 411-416 
    Details
    ISSN: 1432-072X
    Keywords: Key wordsCorynebacterium glutamicum ; Urea uptake ; Secondary transport ; Urease activity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract When Corynebacterium glutamicum is grown with a sufficient nitrogen supply, urea crosses the cytoplasmic membrane by passive diffusion. A permeability coefficient for urea diffusion of 9 × 10–7 cm s–1 was determined. Under conditions of nitrogen starvation, an energy-dependent urea uptake system was synthesized. Carrier-mediated urea transport was catalyzed by a secondary transport system linked with proton motive force. With a K m for urea of 9 μM, the affinity of this uptake system was much higher than the affinity of urease towards its substrate (K m approximately 55 mM urea). The maximum uptake velocity depended on the expression level and was relatively low [2–3.5 nmol min–1 (mg dry wt.)–1].
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002030050591
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  • 6
    Electronic Resource
    Electronic Resource
    Onset of pulmonary involvement in cystic fibrosis (1982)
    Springer
    European journal of pediatrics 139 (1982), S. 239-239 
    Details
    ISSN: 1432-1076
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00442170
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  • 7
    Electronic Resource
    Electronic Resource
    Sputum penetration of fusidic acid in patients with cystic fibrosis (1982)
    Springer
    European journal of pediatrics 138 (1982), S. 172-175 
    Details
    ISSN: 1432-1076
    Keywords: Fusidic acid ; Cystic fibrosis ; Sputum penetration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report the sputum penetration and efficacy of fusidic acid in 16 children with cystic fibrosis (CF) who were hospitalized because of acute respiratory tract infection due to Staphylococcus aureus. Penetration into sputum and response to therapy were evaluated after intravenous and oral drug administration. Oral fusidic acid therapy (approximately 1,000 mg/m2/day) achieved highly satisfactory serum (10–50 μg/ml) and sputum (0.6–4.0 μg/ml) concentrations which were several fold greater than the MIC of the infecting S. aureus strains. The average percentage penetration into sputum during the steady state phase of the concentration-time curve was between 5 and 10%. The efficacy of treatment is reflected by improvement in clinical findings and laboratory data. Eradication of S. aureus from the sputum was documented in 14 of the 16 patients, although 6 months later this was shown to be transient in half of them (7 of 14 patients). No staphylococci resistant to fusidic acid were found. Nine of the 14 children with documented staphylococcal eradication from the sputum had received gentamicin in addition to fusidic acid therapy which could have added antistaphylococcal efficacy. Further investigations are needed to formulate the definitive role of fusidic acid in the antistaphylococcal therapy of patients with CF.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00441148
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  • 8
    Electronic Resource
    Electronic Resource
    Practical interest in the detection of functional abnormalities in infants and children with lung disease (1993)
    Springer
    European journal of pediatrics 152 (1993), S. 382-386 
    Details
    ISSN: 1432-1076
    Keywords: Infant whole-body plethysmography ; Wheezy bronchitis ; Infant respiratory distress syndrome ; Cystic fibrosis ; Bronchial hyperreactivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract There are new techniques which have been developed in order to assess objective functional data concerning the severity and type of abnormalities in infants and children with lung disease. In the present review some applications of the various techniques are given in connection with deductions, which can be based on such functional findings. Insight into the mechanisms leading to lung disease and the institution of appropriate therapeutic guidelines largely depend on whether the degree of pulmonary hyperinflation or restriction, of bronchial obstruction, of bronchial hyperreactivity, of ventilation inequalities and the function of gas exchange can be objectively evaluated. Recent advances in the non-invasive assessment of lung function in infants and children promises progress in this task.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01955891
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  • 9
    Electronic Resource
    Electronic Resource
    Dopamine-beta-hydroxylase in patients with cystic fibrosis (1986)
    Springer
    European journal of pediatrics 145 (1986), S. 80-83 
    Details
    ISSN: 1432-1076
    Keywords: Cystic fibrosis ; Dopamine-beta-hydroxylase ; Catecholamines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The enzymatic activity of plasma dopamine-beta-hydroxylase (DBH) was determined in 92 children/adolescents with cystic fibrosis, in 25 parents (heterozygotes) of these patients and in 68 healthy controls. Statistically significant (P〈0.01) lower DBH levels were found in cystic fibrosis patients (17.9±1.4 μmol/min per 1, SEM) compared to the controls (25.5±2.1 μmol/min per 1). In 37 patients plasma norepinephrine and dopamine levels were compared to the enzymatic activity, no significant correlation between these variables being shown (r=-0.134 for norepinephrine; r=0.159 for dopamine). However, due to the large variability of DBH within the groups and due to the lack of relationship of this enzymatic activity to plasma catecholamines, it is concluded that these differences may neither account for the observed elevation of plasma dopamine in cystic fibrosis patients (0.94–6.73 nmol/l vs. 0.01–0.986 nmol/l for controls) nor for their putative autonomic dysfunction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00441861
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  • 10
    Electronic Resource
    Electronic Resource
    Assessment of lung function in infants and young children with lung disease (1995)
    Springer
    European journal of pediatrics 154 (1995), S. S13 
    Details
    ISSN: 1432-1076
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02191497
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