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Biomedical subjects

R Müller

Publications and source records attributed to R Müller.

At least 631 records · Page 35Linked to original sources
PubMed1986

Effect of recombinant alpha A-interferon on DNA synthesis and differentiation of human keratinocytes in vitro.

Interferons are known to protect cells against virus infection, to inhibit cell growth in a number of cell lines and also to modulate cell differentiation. Their possible clinical application has now entered its final phase. The aim of this investigation was to study the effect of recombinant alpha A-interferon (r IFN-alpha A) on human keratinocyte DNA synthesis and differentiation in vitro. [3H]-TdR incorporation into DNA was used to quantify DNA synthesis in keratinocyte cultures at varying concentrations of rIFN-alpha A. Cell differentiation was determined using polyacrylamide gel electrophoresis of six specific protein fractions extracted from the keratinocytes. Our results indicate that rIFN-alpha A is a potent inhibitor of keratinocyte DNA synthesis in vitro; it also decreases significantly the amount and synthesis of non-covalently bound keratins while increasing the disulphide cross-linked keratins. No qualitative changes in keratinocyte proteins were observed.

Cell Differentiation↗
PubMed1986

Lineage-specific expression of c-fos and c-fms in human hematopoietic cells: discrepancies with the in vitro differentiation of leukemia cells.

In vitro differentiation studies using the bipotential human leukemia cell line, HL60, have indicated that high levels of expression of two proto-oncogenes, c-fos and c-fms, are restricted to the myelomonocytic lineage. No such expression has been detected in induced granulocytic cells. In striking contrast to these observations, we found that c-fos mRNA levels are very high in purified human granulocytes, but barely detectable in blood monocytes and tissue macrophages. Human granulocytes contain, however, relatively low levels of c-fos protein, indicating that c-fos mRNA is inefficiently translated or that the protein is rapidly degraded in these cells. In closer agreement with the in vitro results, the level of the expression of c-fms is high in purified blood monocytes and undetectable in granulocytes. We found, however, that the evolution of monocytes into tissue macrophages is accompanied by a significant decrease in c-fms expression, suggesting that the function of c-fms is restricted to specific stages of monocytic differentiation. Our observations also show that results obtained using in vitro differentiation systems have to be regarded with caution, since they may not reflect the in vivo situation.

Cell Differentiation↗
PubMed1986

The effect of movement adaptation on human cortical potentials evoked by pattern movement.

Human visually evoked cortical potentials (VEPs) were elicited by the onset of movement of grating patterns (test stimuli). The most prominent VEP waves N2 and P2 increased with accelerating test stimulus velocity (within a range of 0.2-4 deg/s). Two kinds of rums were presented. Reference runs involved only test stimuli and stationary pattern periods between them. In test runs moving gratings were additionally presented between the test stimuli effecting a stable level of movement adaptation. The additional movement stimulation reduced the VEP amplitudes throughout. The relative amplitude reduction was nearly constant for all test stimulus velocities if a fixed velocity of the adaptation stimulus was used. When the adaptation stimulus velocity was raised (within a range of 0.1-4 deg/s), the relative VEP amplitude became smaller. The results support the additive model of velocity coding in human occipital cortex rather than the substitutive model.

Adaptation, Physiological↗
PubMed1986

[Arteriosclerotic aneurysms of the right coronary artery in a 56-year-old female].

We report the case of a 56-year-old woman with a saccular aneurysm of the right coronary artery, which was resected. Aneurysmatic coronary artery disease mostly has an arteriosclerotic origin and occurs in patients with coronary artery disease with a frequency of 0.3-4.9%. In the affected patients myocardial infarction is more frequent, but their 5-year survival rate is not diminished. The therapy of choice is, as indicated, aortocoronary bypass grafting.

Aneurysm↗
PubMed1986

[Dicarboxylic acids inhibit the growth of keratinocytes in vitro].

The antiproliferative effect of three straight-chained saturated dicarboxylic acids was examined with neonatal mouse keratinocyte cultures. Adipic acid (C6), azelaic acid (C9), and sebacic acid (C10) were added to the cultures in concentrations ranging from 1 to 50 mmol/l. Proliferation was assayed by liquid-scintillation counting of 3H-thymidine incorporation into DNA and by autoradiography. Fifty percent inhibition of 3H-thymidine incorporation was observed with 50 mmol/l adipic acid, 20 mmol/l azelaic acid, and 10 mmol/l sebacic acid, respectively. The antiproliferative effect was completely reversible after cessation of treatment. Moreover, treated cultures then showed a rebound effect with increased DNA synthesis. These results show that dicarboxylic acids exert reversible antiproliferative effects on keratinocytes.

Adipates↗
PubMed1985

Regulation of c-fos transcription in mouse fibroblasts: identification of DNase I-hypersensitive sites and regulatory upstream sequences.

In quiescent mouse fibroblasts, the c-fos gene is expressed at very low levels, but is rapidly and transiently inducible by peptide growth factors. In this study, we have identified in quiescent cells five DNase I-hypersensitive sites located -1700, -290, +10, +240 and +700 bp relative to the 5' cap site. After serum stimulation, the distinct nuclease hypersensitive site at position +10 rapidly disappeared, and instead a broad region of DNase I accessibility between positions 0 and +250 occurred. Nucleotide sequence analysis of the 5'-flanking region of the mouse c-fos gene showed that the hypersensitive site around position -290 is located in a region that is highly conserved between mouse and human, and that contains an enhancer-like structure. When the mouse c-fos promoter and 351 bp of 5'-flanking sequences were linked to the bacterial chloramphenicol acetyl transferase (CAT) gene and transfected into NIH3T3 cells efficient, constitutive expression of CAT activity was observed, even in unstimulated, quiescent cells. However, removal of a 256-bp stretch upstream from position -95 completely abolished CAT expression, indicating that sequences within a region of approximately 350 bp upstream from the cap site are indispensable for c-fos transcription. In addition, our findings point to the existence of other sequence elements that exert negative regulation in the absence of growth factor stimulation. Such sites may be found around the growth factor-responsive nuclease hypersensitive sites in the vicinity of the cap site.

Acetyltransferases↗
PubMed1985

Prognostic value of thyroid stimulating antibodies and TSH-binding inhibiting immunoglobulins in the follow-up of Graves' disease.

The prognostic value of the determinations of autoantibodies in Graves' disease is still questionable. So far, the role of different assay procedures used has not been intensively investigated. We simultaneously applied two different techniques, a radioreceptor assay and a T3 releasing in vitro assay, in the follow-up of patients with Graves' disease to directly compare the course of the antibody activities determined by these assays and to find out a prognostic significance of the composition of the antibody spectrum present. The initial activities of thyroid stimulating antibodies (TSAb) and TSH-binding inhibiting immunoglobulins (TBII) were not significantly correlated in patients before treatment. During a 12-month antithyroid medication antibody titres showed a concordant course in the majority of patients. In 6 of 25 patients, however, a discordant behaviour was clearly documented including dose-response curves. At the end of treatment, the patients could be divided into three groups: group I included 5 patients positive for both TSAb and TBII, group II 6 patients positive for TBII and negative for TSAb and group III 14 patients negative for both of them. During the following survey of 18 months all patients of group I, 2 patients of group II and 6 patients of group III experienced a relapse of hyperthyroidism. In conclusion, TSAb and TBII activities dissociate in some patients during antithyroid drug therapy. For the individual patient, the disappearance of both TSAb and TBII was no certain indicator for a longstanding remission of Graves' hyperthyroidism. The persistence of TSAb seems to be more reliably associated with persisting or rapidly relapsing disease than the persistence of TBII.

Adult↗
PubMed1985

Molecular cloning and expression of human tumor necrosis factor and comparison with mouse tumor necrosis factor.

U-937 cells, a monocytic line derived from a human histiocytic lymphoma, were induced for human tumor necrosis factor (TNF) secretion into the medium and were used for the preparation of TNF mRNA. Biological activity of the latter was quantified in a Xenopus laevis oocyte injection system. TNF mRNA was enriched by gradient centrifugation and this size-fractionated mRNA was used for synthesis of cDNA and inserted into the unique PstI site of pAT153. A recombinant plasmid containing human TNF cDNA was selected by colony hybridization using an internal fragment of a mouse TNF cDNA clone [Fransen, L., Mueller, R., Marmenout, A., Tavernier, J., Van der Heyden, J., Kawashima, E., Chollet, A., Tizard, R., Van Heuverswyn, H., Van Vliet, A., Ruysschaert, M. R. & Fiers, W. (1985) Nucleic Acids Res. 13, 4417-4429] as a probe. The sequence of this human TNF cDNA is in agreement with the one published by Pennica et al. [Pennica, D., Nedwin, G. E., Hayflick, J. S., Seeburg, P. H., Derynck, R., Palladino, M. A., Kohr, W. J., Aggarwal, B. B. & Goeddel, D. V. (1984) Nature (Lond.) 312, 724-729]. The 157-amino-acid-long mature sequence is about 80% homologous to mouse TNF and its hydrophilicity plot is also very similar, in spite of the apparent species specificity of TNF. In contrast to mouse TNF, it contains no potential N-glycosylation site. When compared to other cytokines, like IFN-beta, IFN-gamma, or IL-2, there is a remarkably high preference for G X C pairs in the third-letter positions. Expression of the TNF cDNA in monkey COS cells or in Escherichia coli gives rise to a protein having similar biological and serological properties as natural human TNF. A human genomic clone was also identified and sequenced; it was found to be in good agreement with the one recently published by Shirai et al. [Shirai, T., Yamaguchi, H., Ito, H., Todd, C. W. & Wallace, R. B. (1985) Nature (Lond.) 313, 803-806], except for some differences in the introns and 5'-untranslated region.

Amino Acid Sequence↗
PubMed1985

The site of cyclic AMP-dependent protein kinase catalyzed phosphorylation of cytochrome P-450 LM2.

The phenobarbital-inducible form of cytochrome P-450 purified from rabbit liver microsomes is phosphorylated by cAMP-dependent protein kinase at a single site, the serine residue in position 128 of the amino acid sequence. The serine is located in a characteristic recognition sequence for cAMP-dependent protein kinase and is part of a primary structure which is conserved during evolution, present also in phenobarbital-inducible rat cytochrome and cytochrome P-450 CAM from Pseudomonas putida. The contribution of these findings to our understanding of the structure and membrane topology of cytochrome P-450 LM2 and its turnover regulated by phosphorylation is discussed.

Amino Acid Sequence↗
PubMed1985

Molecular cloning of mouse tumour necrosis factor cDNA and its eukaryotic expression.

Tumour necrosis factor (TNF), released by induced macrophages, causes tumour necrosis in animals and kills preferentially transformed cells in vitro. mRNA induced in the established mouse monocytic PU 5.1.8 cell line by lipopolysaccharide, was converted into double-stranded cDNA and cloned in the pAT153 vector. Recombinant plasmids were screened by plus-minus hybridization and TNF-specific oligonucleotide probes constructed on the basis of partial amino acid sequences of rabbit TNF. A series of TNF specific clones were identified and confirmed by hybrid selection of mouse TNF-specific mRNA. The sequence codes for a 235 amino acids long polypeptide, of which 156 amino acids presumably correspond to the mature product. It can be concluded that mature mouse TNF is a glycosylated dimer. Biologically active TNF was secreted by both Cos-I and CHO-cells transfected with the chimaeric expression vector pSV2d2-mTNF containing the coding region of the mouse TNF cDNA gene.

Amino Acid Sequence↗
PubMed1985

Assessment of circulating immune complexes by a solid-phase C1q-binding assay during the first hours and days after prolonged exercise.

A sensitive and specific solid-phase C1q-binding assay using porcine C1q and microtitre plates as a solid phase, served to assess the immune complexes in serum during the first hours and days after a 3-h running test. Fourteen moderately trained male subjects participated in the race and covered 36.3 +/- 3.7 (mean +/- SD) km in 3 h. Blood samples were drawn 1 day before, immediately before, immediately after, 1 and 3 h after and 1, 2 and 4 days after the race. When corrected for the changes of serum total protein, the apparent immune complex concentrations were 1 and 3 h after the race significantly higher (p less than 0.001 and p less than 0.05 respectively) than the pre-exercise values. Two days after the race the values were significantly lower (p less than 0.05) than before the race. These findings provide evidence for the formation of immune complexes after severe physical exercise.

Adult↗
PubMed1985

Integration of transfected LTR sequences into the c-raf proto-oncogene: activation by promoter insertion.

A malignant cell line (clone S1) isolated after co-transfection of normal NIH3T3 DNA and Moloney leukemia virus long terminal repeat (Mo-LTR) sequences has previously been described to contain an activated c-raf oncogene. Here, we report the isolation by molecular cloning and the structural analysis of the LTR-activated c-raf gene. As shown by Southern blot and nucleotide sequence analyses, the transfected Mo-LTR sequences integrated into the 5th intron of the endogenous c-raf proto-oncogene. This intragenic LTR insertion led to the expression of high levels of LTR-U5-c-raf hybrid transcripts indicating an initiation of transcription from the Mo-LTR promoter. Transcriptional activation of c-raf is accompanied by the synthesis of large amounts of cytoplasmic c-raf protein. Immunoblot analysis suggests that the proteins encoded by the LTR-activated c-raf gene are truncated compared with the normal c-raf gene product(s). Our results indicate a promoter insertion mechanism of c-raf activation.

Animals↗
PubMed1985

Stimulation and inhibition of growth by EGF in different A431 cell clones is accompanied by the rapid induction of c-fos and c-myc proto-oncogenes.

Stimulation of quiescent fibroblasts to growth by polypeptide growth factors is accompanied by the rapid induction of c-fos and c-myc proto-oncogenes. In contrast to fibroblasts, A431 cells respond to epidermal growth factor (EGF) with a decreased growth rate. Here we report that, in spite of its growth inhibitory effect, EGF rapidly induces transient expression of c-fos mRNA, followed by the synthesis of nuclear c-fos protein. In addition, EGF treatment resulted in elevated levels of c-myc expression. Practically identical results were obtained with variant A431 clones that are resistant to the inhibitory effect of EGF on cell proliferation. These observations suggest that in A431 cells c-fos and c-myc induction is a primary consequence of growth factor-receptor interaction. Indeed, efficient induction of both genes was also observed with cyanide bromide-cleaved EGF, which has previously been shown to be non-mitogenic but able to trigger early events induced by EGF. We observed strong induction of c-fos and to a lesser extent of c-myc also by TPA, and by the calcium ionophore A23187, indicating an important role for kinase C in proto-oncogene activation by growth factors.

Calcimycin↗