[Actinomycosis].
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Biomedical subjects
Publications and source records attributed to C Krautmacher.
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BACKGROUND AND STUDY AIMS: We have conducted a study to compare the diagnostic yields of magnetic resonance imaging (MRI) and capsule endoscopy for the detection of small-bowel polyps in patients with inherited polyposis syndromes. PATIENTS AND METHODS: MRI was performed in 20 patients, with either Peutz-Jeghers' syndrome (PJS; n = 4) or familial adenomatous polyposis (FAP; n = 16), and capsule endoscopy was done the next day. The number, size, and location of polyps were analyzed. RESULTS: Overall, 448 polyps ranging from about 1 mm to 30 mm in size were detected in eight patients by capsule endoscopy, whereas with MRI only 24 polyps all bigger than 5 mm could be seen in the four PJS patients. CONCLUSIONS: Polyps bigger than 15 mm were detected similarly with capsule endoscopy and MRI, whereas smaller polyps were seen much more often with capsule endoscopy. Polyps smaller than 5 mm were exclusively seen with capsule endoscopy. However, location of the detected polyps and determination of their exact sizes was more accurate by MRI.
We have previously shown that hydrogen peroxide is an important mediator of ultraviolet B induced phosphorylation of the epidermal growth factor receptor in human keratinocytes. Here we demonstrate that physiologic doses of ultraviolet B and hydrogen peroxide stimulate activation of two related but distinct mitogen-activated protein kinase pathways: extracellular regulated kinase 1 and 2 (ERK1/2), as well as p38, the mammalian homolog of HOG1 in yeast which is a major kinase for a recently identified stress-induced signaling pathway. The time-dependent activation of ERK1/2 and p38 are distinct, and ultraviolet B-induced ERK1/2 activation is downregulated more rapidly than p38. Using dihydrorhodamine or Amplex as specific fluorescent dye probes, we show that ultraviolet B-induced peroxides can be inhibited by ascorbic acid. Ascorbic acid strongly blocks ERK1/2 and p38 activation by ultraviolet B and hydrogen peroxide whereas pyrrolidine dithiocarbamate and butyl hydroxyanisole are less effective. Pyrrolidine dithiocarbamate was unable to inhibit ultraviolet B-induced p38 activation. Cell death was increased after ultraviolet B when ERK1/2 activation was attenuated by the specific inhibitor PD098059. The distinct time courses and extents of activation and inhibition of ERK1/2 and p38 indicate that these pathways are separate and regulated independently in keratinocytes. Specific types of reactive oxygen species induced by ultraviolet B as well as selective activation or inhibition of specific phosphatases may mediate these responses in keratinocytes. These findings demonstrate that reactive oxygen species are important multifunctional mediators of ultraviolet B-induced ERK1/2 and p38 signaling transduction pathways and suggest that ERK1/2 may play an important part in protecting keratinocytes from cell death following oxidative stress.