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B Kiefer

Publications and source records attributed to B Kiefer.

8 recordsLinked to original sources
PubMed1991

In vitro production of anti-neutrophilocyte-cytoplasm-antibodies (ANCA) by Epstein-Barr virus-transformed B-cell lines in Wegener's granulomatosis.

The frequent detection of anti-neutrophilocyte-cytoplasm-antibodies (ANCA) in patients with Wegener's granulomatosis (WG) led to the supposition that this disease might be of autoimmune nature. For some authors assume that Epstein-Barr virus (EBV) infection of human B-lymphocytes besides polyclonal activation could reveal the cryptic immune status against different autoantigens in patients with autoimmune diseases we investigated EBV-transformed B-lymphocytes from patients with Sjögren's syndrome, mixed connective tissue disease, WG and healthy blood donors. Two stable B-cell lines (Ho3, We1) could be established. Inhibition experiments showed that antibodies produced by transformed B-lymphocytes and serum ANCA (C-ANCA type) of 10 WG patients recognized the identical antigen. Stimulation of one clone (Ho3) with interleukin 6 (IL-6) led to a switch from IgM to IgG production. Antibodies produced by this clone also stained glomeruli of human frozen kidney sections. Western blot analysis using immunoaffinity purified antigen prepared from human granulocytes revealed a reaction with a protein of approx. 29 kD MW. Our data underscore some new aspects concerning the direct pathogenicity of C-ANCA confirming the hypothesis that the autoimmune B-cell repertoire in WG not only reflects a polyclonal B-cell activation but is shaped by antigen driven responses.

Aged↗
PubMed1990

Ca2+ potentiates cAMP-dependent expression of urokinase-type plasminogen activator gene through a calmodulin- and protein kinase C-independent mechanism.

In the porcine renal epithelial cell line, LLC-PK1, activation of the cAMP-dependent signal transduction pathway induces the urokinase-type plasminogen activator (uPA) gene. We show here that the cAMP response is enhanced when the intracellular calcium concentration is increased. When LLC-PK1 cells were treated with the calcium ionophore ionomycin alone, there was no uPA mRNA accumulation. However, in the presence of ionomycin the dose-response of 8-bromo-cAMP (Br-cAMP) with respect to uPA mRNA accumulation was shifted toward the lower concentrations of Br-cAMP. A Northern blot analysis after the inhibition of RNA synthesis and nuclear run-on assays showed that the synergistic effect of Ca2+ could be attributed to increases in uPA gene transcription and mRNA stability. In the presence of cycloheximide, a protein synthesis inhibitor, uPA mRNA was stabilized, but the effect of ionomycin on Br-cAMP-induced mRNA accumulation was still maintained. The result suggests that the Ca2+, at least on transcription, does not require new protein synthesis. Ionomycin treatment did not modify the activity of the cAMP-dependent protein kinase, suggesting that Ca2+ either affects a step in the pathway between the kinase and the uPA gene, or acts independently of the cAMP-dependent protein kinase pathway. The effect of ionomycin was not suppressed by protein kinase C down-regulation nor by inhibitors of calmodulin. Synergism was also observed when Br-cAMP was replaced with calcitonin, a peptide hormone which is coupled to adenylate cyclase, and when ionomycin was replaced with another ionophore A23187, suggesting that the synergism is due to an interaction between cAMP-dependent and Ca2(+)-dependent signal transduction pathways.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1987

Analysis of adenomatous structures in histopathology.

A new idea of structure analysis in histopathology based upon first-order and third-order structures is presented. Networks formed by single cells and by tubulopapillary formations in adenomatous tissue were analyzed. The algorithm applied is based on the neighborhood conditions defined by O'Callaghan, using graph theory procedures. Twenty cases each of healthy colon mucosa, tubulovillous adenomas and highly to moderately differentiated adenocarcinomas of colon plus ten cases of mesotheliomas and ten cases of adenocarcinomas metastatic to the pleura were analyzed. Statistically significant differences were found in the cyclomatic number of neighboring elements. Classification of specimens of colon mucosa using discriminant analysis yielded correct results in 85% of the 20 cases. All ten cases of metastatic adenocarcinoma and nine of the ten cases of mesothelioma were also correctly classified by the same procedure. A trial of prospective diagnostic assistance in routine histology based upon these cases gave correct classification of three mesotheliomas and of two adenocarcinomas. The procedures are now being used successfully in the routine diagnosis of pleural epithelial/biphasic mesothelioma and of pleuritis carcinomatosa.

Adenocarcinoma↗
PubMedDate not supplied

Interaction between spin labels and DPPC vesicles.

1H NMR studies on DPPC vesicles labeled with the spin labels (1,14) or (12,3) have shown that both of the spin labels influence the fatty acid side chains as well as the choline head groups. The spin label (12,3) affects, naturally, the head groups stronger than the spin label (1,14), while the reversed effect can be observed at the side chains. This effect progresses with time after vesicle preparation and is fully developed after about 24 h. Addition of Na-ascorbate, at this time, seems to reverse the effect indicating a stabilizing effect of the vitamin on the membrane. These results could be confirmed by ESR investigations according to which the high-field signal seems to be indicative for changes occurring at the side chains, while the low-field signal seems to reflect modifications of the head groups. Since the spin label (1,14) affects considerably the head groups at temperatures less than 6 degrees C, in which case the spectrum is very similar to that obtained with spin label (12,3) at 24 degrees C, one might conclude that there might be a phase transition in regard to the head groups.

1,2-Dipalmitoylphosphatidylcholine↗