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H Rumpf

Publications and source records attributed to H Rumpf.

10 recordsLinked to original sources
PubMed2002

A reporter-cell assay for the detection of BMP-2 immobilized on porous and nonporous materials.

Human recombinant bone morphogenetic protein-2 (rhBMP-2) immobilized on the surface of metal implants can facilitate osseointegration. Here, we describe a cell reporter assay useful for quantifying small amounts of immobilized rhBMP-2 on various materials. The peptide was dotted and heat-fixed on titanium, 316L stainless steel, nitrocellulose, or glass, and its distribution was monitored by in situ biotinylation followed by detection with the avidin-biotin method. Bioactivity of rhBMP-2 was demonstrated by means of a confluent layer of osteoblastic MC3T3-E1 cells that evenly covered rhBMP-2-free and rhBMP-2-loaded surface areas, as shown with epifluorescence microscopy of calcein acetoxymethyl (AM)-loaded cells. Expression of osteocalcin, fibronectin, actin, and vimentin increased where cells were located on rhBMP-2 dotted areas, but the signal:noise ratio was too low to bioassay the peptide. However, local pronounced expression of alkaline phosphatase was used to quantify BMP-2 in the range of 5-80 ng/dot by means of a cytochemical color reaction for alkaline phosphatase and image analysis of resulting dots. The lower detection limit was in the order nitrocellulose > glass > titanium > 316L steel. We conclude that the cell reporter assay is useful to assess biological activity of rhBMP-2 even after immobilization on three-dimensional implant materials.

Alkaline Phosphatase↗
PubMed2001

Thermal decomposition of (NH4)2[PdCl6] studied by in situ X-ray absorption spectroscopy.

In situ X-ray absorption near edge structure (XANES) investigations were carried out at chlorine K edge and palladium L3 edge to study the mechanism of the thermal decomposition of ammonium hexachloropalladate. The spectra show a characteristic feature for the initial step that might be explained as the formation of the precursor via ligand exchange (Cl --> NH3). Multiple scattering calculations (Feff 8) for the Cl K, Pd and Rh L3 edges were successful in simulating the XANES spectra of the precursor as well as the reference compounds (NH4)2 [PdCl4] and (NH4)3[RhCl6].

Journal Article↗
PubMed1999

Expression of human p53 requires synergistic activation of transcription from the p53 promoter by AP-1, NF-kappaB and Myc/Max.

Transcriptional control of p53 expression participates in the generation of appropriate levels of active p53 in response to mitogenic stimulation. This prompted us to study the role of a putative AP-1 and a NF-kappaB motif in the human p53 promoter for transcriptional regulation. We show that mutation of the AP-1 or the NF-kappaB motif abolishes transcription from the human p53 promoter in HeLa, HepG2 and adenovirus type 5 E1-transformed 293 cells. In comparison, mutation of the previously characterized Myc/Max/USF binding site in the human p53 promoter reduces the transcription rate fivefold. The AP-1 motif in the human p53 promoter binds c-Fos and c-Jun and the NF-kappaB motif binds p50(NF-kappaB) and p65RelA. The cooperative nature of transcriptional activation by these factors was documented by repression of c-fos or NF-kappaB1 translation: Pretreatment of the cells with a c-fos or p50(NF-kappaB1) antisense oligonucleotide suppresses transcription from the human p53 promoter completely. In addition, we show that (a) the level of endogenous p53 mRNA and (b) transcription from the strictly p53-dependent human mdm2 promoter are reduced in the presence of c-fos, c-jun, p50(NF-kappaB1), p65RelA or c-myc antisense oligonucleotides, underscoring the importance of these transcription factors for the expression of functional p53.

Animals↗
PubMed1999

Two domains within the adenovirus type 12 E1A unique spacer have disparate effects on the interaction of E1A with P105-Rb and the transformation of primary mouse cells.

Transformation of primary rodent cells by functions of the adenovirus type 12 (Ad12) early region 1 (E1) is reduced severalfold compared with transformation by E1 of Ad2. We analyzed whether the unique spacer region of Ad12 E1A that borders the conserved region (CR) 2 and represents an oncogenic determinant of Ad12 E1A is involved in this impaired transformation property, putatively by modulating transformation-relevant biological E1A functions. We show that a mutant (E1ASpm1) that lacks 12 amino-terminal residues of the spacer binds p105-Rb and p130 as Ad12 E1A wild type (E1Awt), whereas a second spacer mutant (E1ASpm2) that lacks an adjacent stretch of six alanines exhibits highly reduced binding to p105-Rb. The binding of this mutant to the p130 pocket protein is, however, little impaired. E1ASpm1 diminishes the formation of the p105-Rb-E2F complex more efficiently than E1Awt or, least efficient, E1ASpm2. These properties of the spacer mutants to target and to disintegrate the p105-Rb-E2F complex correspond with their ability to transform primary mouse cells in combination with E1B: E1ASpm1 (plus Ad12 E1B)-transfected cells could be easily established as cell lines, comparable to Ad12 E1Awt- or Ad2 E1Awt-transfected cells. In contrast, cells transfected with E1ASpm2 or Ad12 E1AdelCR2 (lacking the entire CR2) died within 6-10 weeks after replating, although foci were formed in all cases. Of note, the E1ASpm1-transformed cells grow as fast as the Ad2 E1Awt-transformed cells, with a doubling rate of 15 h, whereas the doubling of the Ad12 E1Awt-transformed cells takes approximately 120 h. Moreover, in the established cell lines, the affinity of E1ASpm1 to p105-Rb was higher than with that of E1Awt. Our data suggest the presence of a transformation-suppressing domain within the carboxyl-terminal 12 residues of the Ad12 E1A-unique spacer, whereas the hydrophobic stretch of six alanines in the spacer is required for stable transformation.

Adenovirus E1A Proteins↗
PubMed1997

E1A 12S and 13S of the transformation-defective adenovirus type 12 strain CS-1 inactivate proteins of the RB family, permitting transactivation of the E2F-dependent promoter.

The transformation-defective Vero cell host range mutant CS-1 of the highly oncogenic adenovirus type 12 (Ad12) (Ad12-CS-1) has a 69-bp deletion in the early region 1A (E1A) gene that removes the carboxy-terminal half of conserved region 2 and the amino-terminal half of the Ad12-specific so-called spacer that seems to play a pivotal role in the oncogenicity of the virus. Despite its deficiency in immortalizing and transforming primary rodent cells, we found that the E1A 13S protein of Ad12-CS-1 retains the ability to bind p105-RB, p107, and p130 in nuclear extract binding assays with glutathione S-transferase-E1A fusion proteins and Western blot analysis. Like wild-type E1A, the mutant protein was able to dissociate E2F from retinoblastoma-related protein-containing complexes, as judged from gel shift experiments with purified 12S and 13S proteins from transfection experiments with an E1A expression vector or from infection with the respective virus. Moreover, in transient expression assays, the 12S and 13S products of wild-type Ad12 and Ad12-CS-1 were shown to transactivate the Ad12 E1A promoter containing E2F-1 and E2F-5-motifs, respectively, in a comparable manner. The same results were obtained from transfection assays with the E2F motif-dependent E2 promoter of adenovirus type 5 or the human dihydrofolate reductase promoter. These data suggest that efficient infection by Ad12 and the correlated virus-induced reprogramming of the infected cells, including the induction of cell cycle-relevant mechanisms (e.g. E2F activation), can be uncoupled from the transformation properties of the virus.

Adenoviridae↗
PubMed1995

Immunoprinting reveals different genetic bases for (auto)immuno diseases.

The genetic basis of complex (auto)immune diseases has been studied for an ovine nematode infection, human rheumatoid arthritis (RA), early onset pauciarticular arthritis (EOPA) and multiple sclerosis (MS). Immunoprinting combines the powerful simplicity of polymerase chain reaction (PCR)-based amplification of discrete, highly informative microsatellite loci with the principle of genetic associations. This approach has allowed us to define novel genetic risk factors in adult RA patient categories whereas EOPA forms in juveniles display other prominent genetic contributions. Differentially regulated tumor necrosis factor (TNF) expression may lead to a better understanding of the causal pathogenesis of EOPA while T cell receptor (TCR) gene polymorphisms appear crucial for RA manifestations in certain patient groups. Statistically significant marker associations have still to be defined for MS in larger panels of patient and control cohorts. The clinical course of the disease will probably have to be taken into account when associations with lymphokine levels are evaluated. In essence a convoluted myriad of negative and a few positive disease association data have been generated efficiently by immunoprinting. As expected, the interrelationships are truly complicated between the polymorphic genetic instances predisposing to autoimmune disease. Nevertheless, risk factors may be defined on an individualized basis by indirect gene diagnosis revealing predispositions and providing a more solid basis for differential diagnosis and treatment.

Adult↗
PubMed1995

Immunoprinting excludes many potential susceptibility genes as predisposing to early onset pauciarticular juvenile chronic arthritis except HLA class II and TNF.

DNA profiles (immunoprints) were generated for 120 patients suffering from early onset pauciarticular chronic arthritis (EOPA-JCA) and > 500 healthy controls utilizing highly polymorphic microsatellites in the vicinity of immunorelevant genes. Six T cell receptor (TCR) markers for the CD3D, TCRDVAJ, TEA, TCRBV6S1, BV6S3, BV6S7 and BV13S2 genes were analysed. Furthermore markers for the cell surface molecule CD40L, for cytokine genes (IL-1A, IL-2, IFN-alpha, FGF-alpha, TNF-alpha), the chromosomal region of the IRF2 and the cytokine receptor gene IL5RA were studied as well as two polymorphisms within the promotor region of the TNF-alpha gene. Coding region polymorphisms were evidenced indirectly by repeat length variation or they were predicted from the microsatellite distribution profiles and then confirmed by direct sequence analysis. Statistical evaluations were performed with respect to known predispositions, predominance of females (> 80%) and HLA-DR and -DQ haplotypes. Cell surface molecules (TCR, CD40L, IL5RA) as well as almost all cytokines (IL-1A, IFN alpha, FGFA, IRF2 region) were excluded as predisposing in our JCA panel. The TNF-alpha microsatellite alleles (GT)10-12 contribute considerably to manifestation of the disease, in HLA-DRB1*11(12) individuals (RR = 12.8). The TNF-alpha allele is not found in linkage disequilibrium with HLA-DRB1*11(12) and may be present on either chromosome 6. Thus, a novel susceptibility factor probably within the TNFA/TNFB gene region has been identified via linkage with the TNF-alpha microsatellite allele. Apparently complex compositions of the genetic background rather than single genes provide the precondition for manifestation of the autoimmune disease EOPA-JCA. Immunoprinting unravels the variability of the immunological genome via the semi-directed microsatellite approach efficiently.

Age of Onset↗