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  • Rhizobium  (3)
  • Gene regulation  (2)
  • pharmacokinetics  (2)
  • 5-Hydroxytryptamine  (1)
Materialart
Erscheinungszeitraum
Schlagwörter
  • 1
    Digitale Medien
    Digitale Medien
    Springer
    European journal of clinical pharmacology 46 (1994), S. 261-265 
    ISSN: 1432-1041
    Schlagwort(e): Cystic fibrosis ; Cyclosporin ; pharmacokinetics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Abstract Cyclosporin (CsA) is currently the main immunosuppressive agent used in organ transplantation with considerable improvement in graft survival. Oral CsA solution is highly lipophilic, and its bioavailability may be reduced in cystic fibrosis (CF) heart-lung transplant recipients with pancreatic, gastrointestinal, and hepatic insufficiency. The bioavailability of oral CsA solution in 7 CF transplant recipients (5 male and 2 female with a mean age of 27 years and a mean weight of 49 kg) and 3 non-CF heart-lung recipients (1 male and 2 female with a mean age of 41 years and a mean weight of 60 kg) was studied. Following intravenous CsA administration, the kinetic curves were similar with no significant difference in the volume of distribution and clearance of CsA demonstrated between the CF and non-CF groups. The mean daily dose of oral CsA in 7 CF subjects (23.3 mg·kg−1) was significantly higher than the 3 non-CF heart-lung recipients (4.8 mg·kg−1). The mean maximum blood concentration of CsA for the oral dose was 776 ng·ml−1 for the 7 CF subjects, which was comparable with the mean peak values of 789 ng·ml−1 for the 3 non-CF control subjects. Poor enteral absorption of CsA probably accounts for the significantly lower mean bioavailability in the 7 CF subjects (14.9%) compared with the 3 non-CF control subjects (39.4%). The effects on the bioavailability of oral CsA solution by pancreatic enzymes (Creon) and histamine-2 antagonist (ranitidine) were also evaluated in the 7 CF subjects. No significant difference was demonstrated.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Experimental brain research 93 (1993), S. 293-298 
    ISSN: 1432-1106
    Schlagwort(e): Medial vestibular nucleus ; 5-Hydroxytryptamine ; Serotonin ; Rat
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The effects of 5-hydroxytryptamine (5-HT) and related compounds on the discharge rate of tonically active medial vestibular nucleus (MVN) neurones were studied in an in vitro slice preparation of the dorsal brainstem of the rat. The majority (87 of 107, 82%) of MVN neurones were excited by 5-HT. Nine cells (8%) showed a biphasic response to 5-HT, which consisted of a brief inhibition followed by excitation. Eleven cells (10%) were inhibited by 5-HT. The excitatory effects of 5-HT were mimicked by alpha-methyl-5-HT and antagonised by ketanserin and ritanserin, indicating the involvement of the 5-HT2 subtype of 5-HT receptor. In biphasic cells, blockade of 5-HT2 receptors by ketanserin reduced the excitatory component of the response and revealed an enhanced initial inhibition. The inhibitory effects in biphasic cells, and in cells that showed a pure inhibition in response to 5-HT, were blocked by pindobind-5-HT and mimicked by 8-hydroxy-2-(di-n-propylamino)-tetralin indicating the involvement of 5-HT1A receptors. The significance of these findings in relation to the effects of 5-HT on vestibular reflex function is discussed.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    ISSN: 1432-2048
    Schlagwort(e): Glutamine synthetase ; Leghaemoglobin ; Nitrogenase ; Nitrogen fixation ; Phaseolus ; Rhizobium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The activities of glutamine synthetase (GS), nitrogenase and leghaemoglobin were measured during nodule development in Phaseolus vulgaris infected with wild-type or two non-fixing (Fix-) mutants of Rhizobium phaseoli. The large increase in GS activity which was observed during nodulation with the wild-type rhizobial strain occurred concomitantly with the detection and increase in activity of nitrogenase and the amount of leghaemoglobin. Moreover, this increase in GS was found to be due entirely to the appearance of a novel form of the enzyme (GSn1) in the nodule. The activity of the form (GSn2) similar to the root enzyme (GSr) remained constant throughout the experiment. In nodules produced by infection with the two mutant strains of Rhizobium phaseoli (JL15 and JL19) only trace amounts of GSn1 and leghaemoglobin were detected.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 4
    ISSN: 1617-4623
    Schlagwort(e): Exopolysaccharide ; Legume ; Nodules ; Rhizobium ; Xanthomonas
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A Tn5-induced mutant strain of R. phaseoli which failed to synthesize exopolysaccharide (EPS) was isolated and was shown to induce normal nitrogen-fixing nodules on Phaseolus beans, the host of this Rhizobium species. The corresponding wild-type Rhizobium DNA was cloned in a wide host-range vector and by isolating Tn5 insertions in this cloned DNA, mutations in a gene termed pss (polysaccharide synthesis) were isolated. These were introduced by marker exchange into near-isogenic strains of R. leguminosarum and R. phaseoli which differed only in the identity of their symbiotic plasmids. Whereas the EPS-deficient mutant strain of R. phaseoli induced normal nitrogen-fixing nodules on Phaseolus beans, the same mutation prevented nodulation of peas by a strain of R. leguminosarum which normally nodulates this host. Further, it was found that DNA cloned from the plant pathogen Xanthomonas campestris pathover campestris could correct the defect in EPS synthesis in R. leguminosarum and R. phaseoli and also restored the ability to nodulate peas to the pss::Tn5 mutant strain of R. leguminosarum.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 5
    ISSN: 1617-4623
    Schlagwort(e): Beans ; DNA Sequence ; Gene regulation ; Nitrogen fixation ; Nodulation ; Rhizobium
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A gene termed psi (polysaccharide inhibition), located close to the nodulation genes of the Rhizobium phaseoli symbiotic plasmid pRP2JI inhibited exopolysaccharide synthesis (EPS) and nodulation ability (Nod) in Rhizobium when it was cloned in a multicopy plasmid. The sequence of psi showed that it specified a polypeptide of mol. wt. 10000 that may be associated with the membrane of Rhizobium. A second gene, psr (polysaccharide restoration), was located on pRP2JI. When cloned in multicopy plasmids, psr overcame the EPS and Nod defects in strains carrying multicopy psi. Strains with multicopy psr induced non-fixing nodules on Phaseolus beans. Using gene fusions between psi and lacZ, it was shown that psi inhibited transcription of psr.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 6
    ISSN: 1617-4623
    Schlagwort(e): Gene regulation ; Melanin synthesis ; Nitrogen fixation ; Phaseolus beans ; Rhizobium phaseoli
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The symbiotic plasmid pRP2JI of Rhizobium phaseoli strain 8002 was shown to contain two separate regions of DNA which are required and sufficient for the synthesis of the pigment melanin. One of these regions containing the class II mel gene(s) was located to other genes involved in nodulation and in nitrogen fixation. Mutations in this region abolished both the ability to synthesize melanin and to fix nitrogen in Phaseolus bean root nodules. Mutations in the other, unlinked region, containing class I mel gene(s), also abolished melanin synthesis but did not affect symbiotic nitrogen fixation. Transcriptional fusions between the class I mel gene and the Escherichia coli lacZ gene were constructed and it was demonstrated that the class II mel gene(s) activated their transcription in free-living culture. Further, strains containing the cloned regulatory class II gene(s) synthesized melanin when growing in minimal medium, in contrast to wild-type strains which became pigmented only in complete medium containing yeast extract and tryptone. It was shown by hybridization experiments that the regulatory mel gene was closely linked to or may correspond to the regulatory nifA gene; a fragment of R. phaseoli DNA which included the class II gene(s) of R. phaseoli hybridized to a previously identified nifA-like gene of R. leguminosarum, the species that nodulates peas.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 7
    ISSN: 1573-0646
    Schlagwort(e): pharmacokinetics ; cytosine arabinoside ; delayed release ; arachis oil suspension
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary An attempt was made to create a delayed release preparation of cytosine arabinoside (araC) which could be administered subcutaneously, and would produce plasma levels similar to steady state infusion concentrations. A thixotropic suspension of araC in arachis oil and aluminium distearate was formulated. This preparation was similar to that previously used with bleomycin oil suspension and procaine penicillin. Two hundred mg/ml of araC in arachis oil containing varying amounts of aluminium distearate were administered firstly to New Zealand White rabbits and then to patients with acute myelogenous leukaemia. This preparation was well tolerated by both rabbits and patients but did not delay the release of araC from the subcutaneous tissues.
    Materialart: Digitale Medien
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