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  • 1990-1994  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 102 (1993), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract Flow-cytometry was used to measure cell volumes and DNA contents of single cells in cultures of soil bacteria during exponential growth and starvation conditions. DNA was measured after staining with mitramycin/ethidium bromide. The measurement of DNA was calibrated with rifampicin-treated cells of E. coli containing even numbers of genomes per cell. Cell volumes were assessed by scatter light measurements. Constant DNA to biovolume relations over a range of cell sizes were found for each of the bacteria at exponential growth, and DNA contents per cell varied over a range equivalent to 1–4 genomes per cell. At generation times of 1.0–1.5 h, two genomes were registered as a mean. After starvation of washed cells in a salt solution (24 hrs), a fraction of the cells in each culture had DNA contents equivalent to 1 genome, but significant fractions retained DNA contents equivalent to 2–4 genomes. Attempts to create cells with even numbers of genomes per cell by treatment with rifampicin was successful on an Acinetobacter sp. In contrast, the response to rifampicin was less clear for Pseudomonas fluorescens and P. chlororaphis, and unclear for the gram positive bacteria isolated from soil. The mean decrease in biovolume upon starvation was 4.1 times (range 1.3–8.1 times) and larger than the mean decrease in DNA content of 1.8 (range 1.3–2.7 times). Cell volume determinations by measurements of scatter light was compared with volume determinations by fluorescence microscopy. The amounts of scatter light per volumes was variable, not only did we find large differences between bacterial types, but also between starving and exponentially growing cells of the same isolate. In order to use light scatter as a measure of biovolume, internal standards has to be chosen of comparable size and surface properties as to soil bacteria.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1262
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Ce travail étudie les effects d'un traitement avec 2 mg d'hormone de croissance humaine bio-synthétique (b-hGH)/kg/jour commencé avant l'intervention sur la résistance à la rupture et le dépot de collagène des anastomoses coliques gauches expérimentales et du colon intact chez des rats opérés fictivement. La pression de rupture anastomotique était 55% plus élevée chez les animaux traités par b-hGH au deuxième jour (p〈0.05) et 79% plus élevée au jour 4 (NS, p=0.056), et la tension de rupture pariétale était 65% plus élevée au jour 2 (p〈0.05) et 112% plus élevée au quatrième jour post-opératoire (p〈0.05) que chez les contrôles. Le contenu en hydroxyproline du segment anastomotique chez les animaux traités augmentait de 56% au 4ème jour (p〈0.005) et de 30% au sixième jour post-opératoire (p〈0.05), comparé avec les contrôles. A trois centimètres en amont des anastomoses les faits démontraient que le poid sec dégressé et le contenu en hydroxyproline des colons cicatrisés était accru après le sixi⪻me jour en comparaison avec les rats opérés fictivement. Il n'y avait cependant aucune diffécence entre les rats traités et les contrôles appareillés indiquant que l'hormone de croissance n'est pas intéressée par ce processus.
    Notes: Abstract This study examined the effects of preoperative treatment with 2.0 mg biosynthetic human growth hormone (b-hGH)/kg/day on the bursting strength and collagen deposition of experimental left colonic anastomoses, and of intact colon from sham-operated rats. The anastomtic bursting pressure was 55% higher in the b-hGH treated animals on day 2 (p〈0.05) and 79% higher on day 4 (NS; p=0.056), and the bursting wall tension was 65% higher on day 2 (p〈0.05) and 112% higher on day 4 postoperatively (p〈0.05), than saline-injected controls. The hydroxyproline content of the anastomotic segment in the b-hGH treated rats increased by 56% on day 4 (p〈0.005) and by 30% on day 6 postoperatively (p〈0.05), compared with controls. At 3 cm proximal to the anastomoses the defatted dry weight and hydroxyproline content of the healing colons were increased after 6 days compared with the sham-operated rats. There was, however, no difference between the b-hGH treated rats and the paired controls, indicating that growth hormone is not involved in this process.
    Type of Medium: Electronic Resource
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