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C Epplen

Publications and source records attributed to C Epplen.

49 records · Page 3Linked to original sources
PubMed1993

Novel members and germline polymorphisms in the human T-cell receptor Vb6 family.

The human T-cell receptor (Tcr) Vb6 family has been scrutinized for polymorphisms, both in coding as well as in intronic sequences by polymerase chain reaction (PCR), subsequent multiple electroblot hybridizations, and sequence analysis. Multiplex PCR is an efficient means of screening for Tcr variability. Four novel loci could be distinguished and several new alleles are described including two pseudogenes. The Vb6 family is characterized by an intronic stretch of simple repetitive (gt)n sequences. These elements are hypervariable, especially in the Vb6.7 subfamily, where they are particularly long. The unexpected persistence of simple repetitive sequences in Tcr and major histocompatibility complex (MHC) class II genes over extended periods of the vertebrate evolutionary history can be interpreted in parallel terms in both gene families.

Amino Acid Sequence↗
PubMed1993

Chromosomal assignment of the human smg GDP dissociation stimulator gene to human chromosome 4q21-q25.

The 3'-end of the cDNA encoding the smg GDP dissociation stimulator (smg GDS) protein shares 100% homology with the previously published expressed sequence tag 00038 site. This site extends the 3'-end of the smg GDS gene by 212 bp. It has been localized to human chromosome 4. Here, we have refined the localization of smg GDP to human chromosome 4q21-q25 using a mapping panel of rodent/human somatic cell hybrids containing different parts of chromosome 4. This chromosomal localization of smg GDP to 4q21-25 overlaps with a region of allele loss in primary hepatocellular carcinoma (4q13-q26).

Animals↗
PubMed1992

On the potential of simple repetitive DNA for fingerprinting in clinical, forensic, and evolutionary dynamic studies.

The purpose of this review is to discuss critically the practical meaning of a specific genome component, simple repetitive desoxyribonucleic acid (DNA) sequences as clinical and forensic and diagnostic and research tools. Previously, multilocus DNA fingerprinting was the major technology employed to visualize such simple repeat sequences. This technique enables many polymorphic loci to be simultaneously detected thus yielding vast amounts of information. With the advent of enzymatic DNA amplification via the polymerase chain reaction (PCR), individual simple repeat loci can be demonstrated, theoretically even from single DNA molecules and so a wealth of additional approaches have also become feasible. In general investigating, small, known, single copy parts of genomes have not posed truly insurmountable problems if enough material was available. There have even been a few (anecdotal) reports on the amplification of simple repeats from ancient DNA (see, e.g. [30]. Here we would like to after a solid basis for an earnest discussion of the applications of these simple repetitive sequences using various methodological approaches relevant for clinical diagnosis, setting aside the obvious unsolved mysteries of their biology.

Animals↗
PubMed1992

Gene expression and localization of opioid peptides in immune cells of inflamed tissue: functional role in antinociception.

Our previous studies indicate that endogenous opioids (primarily beta-endorphin) released during stressful stimuli can interact with peripheral opioid receptors to inhibit nociception in inflamed tissue of rats. This study sought to localize opioid precursor mRNAs and opioid peptides deriving therefrom in inflamed tissue, identify opioid containing cells and demonstrate their functional significance in the inhibition of nociception. In rats with Freund's adjuvant-induced unilateral hindpaw inflammation we show that: (i) pro-opiomelanocortin and proenkephalin-mRNAs (but not prodynorphin mRNA) are abundant in cells of inflamed, but absent in non-inflamed tissue; (ii) numerous cells infiltrating the inflamed subcutaneous tissue are stained intensely with beta-endorphin and [Met]enkephalin (but only few scattered cells with dynorphin) antibodies; (iii) beta-endorphin is present in T- and B-lymphocytes, monocytes and macrophages; and (iv) whole-body irradiation suppresses stress-induced antinociception in the inflamed paw. Taken together, these data suggest that endogenous opioid peptides are synthesized and processed within various types of immune cells at the site of inflammation. Immunosuppression abolishes the intrinsic antinociception in inflammatory tissue confirming the functional significance of these cells.

Analysis of Variance↗
PubMed1992

Self-reactive and antigen-specific T cell clones derived from a HLA-DR4+/DR5+ donor: T cell receptors and MHC-restriction patterns.

The relationship of heat shock proteins and rheumatoid arthritis as well as the relevance of autoreactivity in this disease is unclear. T cells of six individuals (four expressing the DRB1*0401 allele, one harboring DRB1*0404 and one the DRB1*0407 allele) were cloned in the presence of 65kD mycobacterial heat shock protein (HSP60) in order to determine T cell receptors (TcR) used and the MHC class II restriction patterns of potentially relevant T cell clones (TcC). All TcC obtained were not specific for HSP60, but six TcC of one donor (HLA-DR4/HLA-DR5) were responsive towards autologous antigen-presenting cells. One TcC displayed authentic autoreactivity whereas five TcC reacted specifically to serum proteins. The amino acids (aa) of the MHC molecule, crucial for immune recognition were mapped to aa #71 or #86 of either maternal or paternal origin. The strictly autoreactive TcC did not recognize transfected L cells implicating specificity for self-peptides not presented by L cells or the involvement of adhesion molecules. Correlations between autoreactivity and TcR V(D)J sequences or N nucleotides of various "autoreactive" TcC were not evident.

Amino Acid Sequence↗
PubMed1992

Oligonucleotide fingerprinting as a means to identify and survey long-term cultured B cell hybridomas and T cell lines.

Common problems encountered during cell culture are cross-contamination, instability, and inadvertent exchange of cells. Here we report on the application of oligonucleotide fingerprinting as a simple and efficient method to screen hybridomas and T cell lines. Among the fingerprint probes tested, the simple repetitive oligonucleotide (CAC)5/(GTG)5 proved to be most useful for obtaining many fragments specific for each cell line. Because of variable loss of chromosomes, cloned hybridoma cells from one fusion exhibit different fingerprint patterns. Thus, antibody-secreting B cell hybridomas can be distinguished easily even when they originate from the same fusion. Furthermore, we were able to monitor the genomic integrity of myelomas and hybridomas over a period of more than 2 years, thereby highlighting long-term stability. Another application of the method is the control of T cell lines requiring irradiated or mitomycin-treated feeder cells for continuous growth or cloning. There cell lines are always threatened to be overgrown by feeder cells that have escaped from the lethal pretreatment. T cell clones of one individual, known to display differently rearranged T cell receptors, did not show differences in their fingerprint patterns. However, in EBV-transformed cloned B cells, slight differences between clones from the same donor were identified.

B-Lymphocytes↗
PubMed1991

Oligonucleotide fingerprinting using simple repeat motifs: a convenient, ubiquitously applicable method to detect hypervariability for multiple purposes.

A panel of simple repetitive oligonucleotide probes has been designed and tested for multilocus DNA fingerprinting in some 200 fungal, plant and animal species as well as man. To date at least one of the probes has been found to be informative in each species. The human genome, however, has been the major target of many fingerprinting studies. Using the probe (CAC)5 or (GTG)5, individualization of all humans is possible except for monozygotic twins. Paternity analyses are now performed on a routine basis by the use of multilocus fingerprints, including also cases of deficiency, i.e. where one of the parents is not available for analysis. In forensic science stain analysis is feasible in all tissue remains containing nucleated cells. Depending on the degree of DNA degradation a variety of oligonucleotides are informative, and they have been proven useful in actual case work. Advantages in comparison to other methods including enzymatic DNA amplification techniques (PCR) are evident. Fingerprint patterns of tumors may be changed due to the gain or loss of chromosomes and/or intrachromosomal deletion and amplification events. Locus-specific probes were isolated from the human (CAC)5/(GTG)5 fingerprint with a varying degree of informativeness (monomorphic versus truly hypervariable markers). The feasibility of three different approaches for the isolation of hypervariable mono-locus probes was evaluated. Finally, one particular mixed simple (gt)n(ga)m repeat locus in the second intron of the HLA-DRB genes has been scrutinized to allow comparison of the extent of exon-encoded (protein-) polymorphisms versus intronic hypervariability of simple repeats: adjacent to a single gene sequence (e.g. HLA-DRB1*0401) many different length alleles were found. Group-specific structures of basic repeats were identified within the evolutionarily related DRB alleles. As a further application it is suggested here that due to the ubiquitous interspersion of their targets, short probes for simple repeat sequences are especially useful tools for ordering genomic cosmid, yeast artificial chromosome and phage banks.

Animals↗
PubMed1991

[Induction of autoreactive T-cells by bacterial stress proteins in HLA-DR4 donors].

From the peripheral blood of HLA-DR4+ healthy donors or patients with rheumatoid arthritis autoreactive T-cell lines were obtained after stimulation with bacterial heat-shock protein. All lines obtained express an alpha/beta-T-cell receptor and they are predominantly CD4+. The determination of the fine specificity of those autoreactive T cells showed, that either amino-acid position #71 or #86 of the HLA-DR beta 1 chain was critical for recognition by the antigen receptor.

Blood Donors↗
PubMed1989

DNA fingerprinting with the oligonucleotide probe (CAC)5/(GTG)5: somatic stability and germline mutations.

DNA fingerprints were generated from various human somatic tissues and from peripheral blood of 179 children and their 80 parents using (CAC)5/(GTG)5 oligonucleotide probes. Whereas somatic stability of the fingerprint patterns was demonstrated, the average rate for germline mutations was estimated to be approximately 0.001 per DNA locus and gamete, with the three different restriction enzymes used. Seven out of eight mutations observed appeared to be of paternal origin.

Base Sequence↗
PubMedDate not supplied

Chromosomal organization of simple repeated DNA sequences used for DNA fingerprinting.

Stretches of short, simple DNA sequences are widespread in all eukaryote genomes studied so far. Simple sequences are thought to undergo frequent expansion and deletion due to intrinsic genomic mechanisms. Some of the simple sequences were used successfully to detect hypervariable loci in various genomes. Hybridization experiments using synthetic probes not only revealed the informative simple repeats suitable for DNA fingerprinting in a particular species, but also reflected the wide range of distribution of the simple sequences among eukaryotes. The organization of these simple repetitive sequences at the chromosomal loci was investigated using in situ hybridization with chemically synthesized, pure oligonucleotide probes. Both biotin- and digoxigenin-attached probes detected specific chromosomal sites that are enriched in the respective simple-repeat blocks. Depending on the organism and probe used, accumulation of simple DNA sequences at individual or multiple sites on the chromosomes of different vertebrates could be demonstrated. The simple repetitive DNA sequences are located in different chromosomal regions (e.g., heterochromatin on the sex chromosomes, nucleolus organizer regions, and R-band sites), which are constrained considerably during evolution.

Amphibians↗
PubMedDate not supplied

Extensive gene flow in human populations as revealed by protein and microsatellite DNA markers.

Population genetic studies are mainly based on the description of genetic variability and on interpopulational comparisons using genetic distance measures. The evolutionary dynamics of the populations are inferred from these parameters and accurate estimates of gene flow may be critical. The present study reevaluates the role of gene flow in human populations by different statistical methods from a number of microsatellite and protein polymorphism data. The estimated number of individuals exchanged per generation (Nm) was greater than 1 in all data sets with all statistical methods. The correlation between geographic and genetic distances suggests a pattern of isolation by distance, characteristic of demographic and genetic equilibrium conditions among populations worldwide. Thus the high values of Nm may be interpreted as a reflection of high gene flow between geographically close populations. As expected, gene flow appears to exert a pivotal role in the genetic history of humans.

Gene Frequency↗