In 30 male Wistar rats, monosynaptically evoked field potentials in the dentate gyrus were registered under different conditions of repetitive stimulation and the long-term changes in synaptic transmission studied. Low-frequency stimulation induces a habituation-like decrement of the field-EPSP, but not of the population spike which interferes with the maintenance of LTP when administered after tetanic stimulation. The habituation-like response decrement, however, does not influence paired pulse-depression seen with an interstimulus interval of 20.0 ms. The paired pulse-plasticity, on the other hand, can be influenced by the tetanic stimulation (diminution of facilitation or depression), being dependent on the intensity of test stimuli. The results can be interpreted in terms of a complex influence of low-frequency- and tetanic stimulation on the elements of the dentate local circuitry and point to the necessity of considering long-term plastic changes in the investigation of substance- or stimulation-induced deviations of neuronal responses.

Action Potentials↗

PubMed1989

Immunoelectron microscopy of Bacillus subtilis cells secreting human interferon alpha 1 or staphylokinase.

Post-embedding labelling techniques with colloidal gold-IgG or -protein A complexes were used to determine the subcellular location of IFN alpha 1 and staphylokinase secreted from Bacillus subtilis GB500 cells. Both proteins were present in the cytoplasma and the cell envelope pointing to a posttranslational mode of translocation across the cytoplasmic membrane. 5- to 10-fold higher concentrations of gold particles per 0.1 micron 2 were found on the cell envelope and clustering was observed suggesting preferential regions for secretion sites. Several control experiments ensured the specificity of the labelling data.

Bacillus subtilis↗

PubMed1989

Demonstration of capsules in Clostridium difficile.

In four strains of Clostridium difficile the formation of capsules was demonstrated by light and electron microscopy.

Carbon↗

PubMed1989

[Dislocation of the peroneal tendon].

Anatomic, histological and experimental investigations show that for preventing luxation of the peroneal tendons, the shape of the retromalleolar groove is less important. The deciding structure is the retinaculum musculorum peroneorum superius. A subtly differentiated way for diagnosis and therapy, depending on the natural anatomy is presented. The results of a follow-up examination of 31 patients are reported.

Ankle Injuries↗

PubMed1989

Steroid hormones: modulators of Na+ absorption and Cl- secretion in cultured tracheal epithelia.

Cultures of tracheal epithelial cells from adult nonpregnant female rabbits maintained a different balance of Na+ absorption and Cl- secretion from cells of pregnant animals and fetal cultures. Cells of nonpregnant rabbits had a large Na+ absorptive current (11 microA/cm2 or 53% of baseline short circuit current) and a small Cl- secretory current (2.4 microA/cm2 or 11%). In contrast, fetal cells had greater Cl- secretion (15.1 microA/cm2 or 61%) and much less Na+ absorption (1.6 microA/cm2 or less than 10%). Cells of pregnant animals had amounts of Cl- secretion (11.4 microA/cm2 or 41%) and Na+ absorption (6.7 microA/cm2 or 22%) that were in between that of fetal and adult nonpregnant animals. In addition to these striking differences in baseline ion transport among the three groups, epinephrine was found to stimulate Cl- secretion in cells from pregnant rabbits, both Na+ absorption and Cl- secretion in cells from nonpregnant animals, and neither in fetal cells. Steroid hormones of pregnancy, progesterone and estradiol, when added to cells cultured from nonpregnant rabbits, altered the magnitudes of the individual transport pathways to mimic cells cultured from pregnant animals. In addition to changing baseline transport, these steroids modified the epinephrine-stimulated currents to resemble those in the fetus and in pregnancy. We conclude that steroid hormones regulate the balance of Na+ absorption and Cl- secretion in tracheal epithelia in utero and in adulthood.

Animals↗