0000000000345175
AUTHOR
Dirk Schäfer
showing 6 related works from this author
Cytotoxicity of Root Canal Filling Materials to Three Different Human Cell Lines
2001
The aim of this study was to investigate the biological compatibility of five root canal sealers (Sealapex, Endion, Super-EBA, Ketac-Endo, and AH Plus) and regular and calcium hydroxide-based gutta-percha in three different human cell lines. Cultures without root canal sealers were used as controls. Cell growth, cell morphology, cell viability, protein content of the cells, and prostaglandin E 2 (PGE 2 ) release were used as parameters to determine the cytotoxicity of the materials. The protein content of the three cell lines—nasal fibroblasts, gingival fibroblasts, and epithelial tumor cells—was significantly reduced (p ≤ 0.001) by all materials tested. Determinations of PGE 2 release show…
Aspirin Intolerance in Patients with Chronic Sinusitis
1999
Aspirin intolerance in patients with chronic sinusitis is often a cause of early recurrence of symptoms after surgical treatment. This study assesses 84 patients who were tested for acetylsalicylic acid intolerance after presenting with symptoms like chronic rhinosinusitis, sometimes bronchial asthma, coexisting allergies or a history of aspirin sensitivity. Nasal polyposis was found in a majority of cases, often recurrent after previous surgery. The levels of eicosanoids such as peptido-leukotrienes and prostaglandin E<sub>2</sub> were analyzed in isolated blood cells and compared with a healthy control group. Aspirin-intolerant patients showed elevated basal levels of peptido-…
Stimulation of endothelial nitric oxide synthase by proinsulin C-peptide.
2003
There is increasing evidence for biological functions of human C-peptide. Recently, we have described that proinsulin C-peptide increases nutritive capillary blood flow and restores erythrocyte deformability in type 1 diabetic patients, whereas it has no such effect in non-diabetic subjects. The aim of the current study was to elucidate cellular mechanisms of this vasodilator effect in vitro by measuring the nitric oxide (NO)-mediated increase of cGMP production in a RFL-6 reporter cell assay and by demonstrating endothelial calcium influx with the Fluo-3 technique. C-peptide increased the release of NO from endothelial NO synthase (eNOS) in bovine aortic endothelial cells in a concentratio…
COX-2 expression in the guinea pig cochlea is partly altered by moderate sound exposure.
2006
The cyclooxygenase-2 isoform (COX-2) was found recently to be constitutively expressed in the guinea pig inner ear. To gain knowledge about its role in sound perception, alterations in the COX-2 level of moderate noise-stimulated cochleae were determined. Staining intensities were quantified in different regions using an immunohistochemical staining procedure and computer-assisted system. After 70 dB and 90 dB noise exposure for 1 h at 8000 Hz, COX-2 downregulation was observed in the organ of Corti, which was most prominent in Deiters' cells near Hensen cells and outer hair cells. In pillar cells, COX-2 levels were only slightly reduced after 70 dB but strongly diminished after 90 dB expos…
Prostaglandin E2 activates the ciliary beat frequency of cultured human nasal mucosa via the second messenger cyclic adenosine monophosphate.
2001
Prostaglandins influence the ciliary beat frequency (CBF) of ciliated nasal epithelial cells and a stimulatory effect has been described for prostaglandin E2 (PGE2). Until now, it is not known whether PGE2 has direct ciliostimulatory properties or acts through a second messenger. In this study we investigated whether cyclic adenosine monophosphate (cAMP) is implicated in the signal transduction pathway of PGE2-induced activation of CBF. Ciliated cells of the nasal mucosa were cultured for up to 5 days whereafter the culture medium was removed and the cells were incubated with different concentrations of test solutions. The ciliated cells were recorded under a phase-contrast microscope and v…
The exposure of healthy volunteers to 200 ppm 1,1,1-trichloroethane increases the concentration of proinflammatory cytokines in nasal secretions
1999
Objectives: Irritating effects of organic solvents have usually been measured by means of questionnaires. The aim of the present study was to evaluate the sensitivity of different methods of detecting subclinical irritating effects. Methods: Twelve healthy, non-smoking students were exposed to 200 ppm and to 20 ppm 1,1,1-trichloroethane in an exposure chamber, using a crossover design. The amounts of interleukins (IL)-1β, IL-6 and IL-8 and prostaglandin E2 (PGE2) in nasal secretions were measured. Mucociliary transport time was determined with the saccharine test. Ciliary beat frequency of nasal epithelial cells was measured with video-interference contrast microscopy. Subjective symptoms w…