PubMed Health⌕ Search

Biomedical subjects

I Böhm

Publications and source records attributed to I Böhm.

36 records · Page 2Linked to original sources
PubMed1995

Direct molecular analysis of the fragile X syndrome in a sample of Egyptian and German patients using non-radioactive PCR and Southern blot followed by chemiluminescent detection.

Molecular genetic analysis of individuals from 6 Egyptian and 33 German families with fragile X syndrome and 240 further patients with mental retardation was performed applying a completely non-radioactive system. The aim of our study was the development of a non-radioactive detection method and its implementation in molecular diagnosis of the fragile X syndrome. Furthermore, we wanted to assess differences in the mutation sizes between Egyptian and German patients and between Egyptian and German carriers of a premutation. Using non-radioactive polymerase chain reaction (PCR), agarose gel electrophoresis and blotting of the PCR products, followed by hybridisation with a digoxigenin-labelled oligonucleotide probe (CGG)5 and chemiluminescent detection, we identified the fragile X full mutation (amplification of a CGG repeat in the FMR-1 gene ranging from several hundred to several thousand repeat units) in all patients. We observed no differences in the length of the CGG repeat between the Egyptian and German patients and carriers, respectively. However, in one prenatal diagnosis, we detected only one normal sized allele in a female fetus using the PCR-agarose assay, whereas Southern blot analysis with the digoxigenin labelled probe StB 12.3 revealed presence of a full mutation. Our newly established nonradioactive genomic blotting method is based on the conventional radioactive Southern blot analysis. Labelling of the probe StB 12.3 with digoxigenin via PCR allowed the detection of normal, premutated and fully mutated alleles. For exact sizing of small premutated or large normal alleles, we separated digoxigenin labelled PCR products through denaturing polyacrylamide gelelectrophoresis (PAGE) and transfered them to a nylon membrane using a gel dryer. The blotted PCR-fragments can easily be detected with alkaline phosphate-labelled anti-digoxigenin antibody. The number of trinucleotide repeat units can be determined by scoring the detected bands against a digoxigenated M13 sequencing ladder. Our newly developed digoxigenin/chemiluminescence approach using PCR and Southern blot analysis provides reliable results for routine detection of full fragile X mutations and premutations.

Base Sequence↗
PubMed1994

Posttranslational modification of nitrogenase. Differences between the purple bacterium Rhodospirillum rubrum and the cyanobacterium Anabaena variabilis.

In the photosynthetic bacteria Rhodospirillum rubrum and Rhodopseudomonas capsulatus post-translational regulation of nitrogenase is due to ADP-ribosylation of the Fe-protein, the dinitrogenase reductase [Burris, R. H. (1991) J. Biol. Chem. 266, 9339-9342]. This mechanism has been assumed to be responsible for nitrogenase modification in a variety of organisms. In the present study, we examined whether ADP-ribosylation holds true for the filamentous cyanobacterium Anabaena variabilis. Genes coding for the nitrogenase-modifying enzymes dinitrogenase reductase-activating glycohydrolase (DRAG) and dinitrogenase reductase ADP-ribosyl transferase (DRAT) from R. rubrum have been subcloned and overexpressed in Escherichia coli. After isolation under anaerobic conditions, both proteins were functional as determined by in-vitro assays using nitrogenase from R. rubrum as substrate. In contrast to the R. rubrum enzyme, nitrogenase from A. variabilis was not affected by DRAG or DRAT. Neither could inactive nitrogenase be restored by DRAG, nor nitrogenase activity suppressed by DRAT. Using specific antibodies against arginine-bound ADP-ribose [Meyer, T. & Hilz, H. (1986) Eur. J. Biochem. 155, 157-165], immunoblotting of the inactive, modified form of the Fe-protein from R. rubrum but not that from A. variabilis showed a strong cross reaction. Furthermore, differently to R. rubrum no ADP-ribosylated proteins could be detected at all, indicating the absence of this posttranslational modification in A. variabilis.

ADP Ribose Transferases↗
PubMed1994

[Successful treatment of panarteritis nodosa with low-dose methotrexate therapy].

We report on a 45-year-old male patient who presented a classic polyarteritis nodosa (PAN). The clinical course extended over 7 years. In spite of 2 years immunosuppressive therapy with azathioprine and methylprednisolone the course was progressive. Low-dose methotrexate therapy was the only treatment that controlled the disease, leading to rapid clinical and histopathological remission. In low concentrations methotrexate acts as an IL-1 inhibitor, and it obviously suppresses the pathogenetic mechanism of PAN.

Arteries↗
PubMed1993

Oligonucleotide DNA fingerprinting: results of a multi-center study on reliability and validity.

We report the results of an empirical study of 256 paternity cases referred to 7 different German laboratories for DNA fingerprinting with oligonucleotide probe (CAC)5/(GTG)5. All parameters characteristic of such multilocus DNA fingerprints were found to differ significantly between the contributing centres. Despite these differences, clear-cut decisions between paternity and non-paternity could be made in all but one case. Furthermore, we found no systematic deviation of the gel-phenotype distribution among trios from random expectation as derived from commonly adopted analytical models. Thus, we conclude that oligonucleotide DNA fingerprinting is a robust and reliable means for the resolution of paternity cases.

Base Sequence↗
PubMed1993

Paternity testing with oligonucleotide multilocus probe (CAC)5/(GTG)5: a multicenter study.

The statistical analysis is reported of 256 paternity cases referred to seven different German laboratories for multilocus DNA fingerprinting with oligonucleotide probe (CAC)5/(GTG)5 and restriction enzyme HinfI. All parameters characteristic of multilocus DNA fingerprints were found to differ significantly between the contributing centres: the number of analyzed gel positions, the number of bands scored per individual, the probability of occurrence of a band at a particular position, and the band-sharing probabilities between the mother and both child and alleged father. Despite these differences, paternity cases could be divided clearly into two distinct subgroups on the basis of (i) offspring bands that could not be assigned to either the mother or the alleged father and (ii) the extent of band-sharing between child and alleged father. This partitioning, which is likely to correspond to true and false paternity, confirms previous findings for other multilocus probes. A goodness-of-fit test on the normalized number of bands scored per individual revealed no systematic deviations from commonly adopted analytical models regarding electrophoretic bands as independent entities. Log10-likelihood ratios of paternity vs. non-paternity were calculated utilizing one of these models, and a clear-cut partitioning was again obtained which coincides with that mentioned before. Only one case could not be decided unambiguously, and was either due to two independent mutations or to a close relative of the alleged father being the true father.

Child↗
PubMed1993

Mechanism of action of methotrexate: experimental evidence that methotrexate blocks the binding of interleukin 1 beta to the interleukin 1 receptor on target cells.

Interleukin 1, a multifunctional cytokine, plays a central role in inflammatory processes and induction of the immune response. Target cells possess 200-5000 (or more) interleukin 1 receptors per cell, but they exhibit a full biological response when only 1-2% of these receptors are occupied by interleukin 1 alpha or 1 beta. Methotrexate has been reported to be beneficial in several inflammatory and autoimmune diseases. On the other hand, many of these diseases are known to share an overproduction of interleukin 1. It has been demonstrated that methotrexate has no influence on the interleukin 1 synthesis, so we focused our attention on the ability of methotrexate to interfere with the binding of interleukin 1 beta to the interleukin 1 receptor. The experiments were performed on monocytes, lymphocytes and granulocytes using a recombinant human cytokine probe. Methotrexate led to an astonishing decrease in the binding of interleukin 1 beta to the interleukin 1 receptor of peripheral blood cells, whereas methylprednisolone and indomethacin were not inhibitory. The inhibitory effect of methotrexate was dose dependent. An excess of interleukin 1 beta abolished the inhibition of cytokine binding by methotrexate. We also demonstrated that methotrexate does not affect the integrity of the interleukin 1 receptor or of the target cells. Our results demonstrate that methotrexate blocks the interleukin 1 beta-interleukin 1 receptor pathway. Methotrexate is therefore another interleukin 1 inhibitor and a clinically efficient anticytokine.

Flow Cytometry↗
PubMed1992

In vitro activation of dinitrogenase reductase from the cyanobacterium Anabaena variabilis (ATCC 29413).

Nitrogenase of the heterocystous cyanobacterium Anabaena variabilis was inactivated in vivo (S. Reich, H. Almon, and P. Böger, FEMS Microbiol. Lett. 34:53-56, 1986). Partially purified and modified (inactivated) dinitrogenase reductase (Fe-protein) of such cells was reactivated by isolated membrane fractions of A. variabilis or of Rhodospirillum rubrum, and acetylene reduction was measured. Reactivation requires ATP, Mg2+, and Mn2+. The activating principle is localized in the heterocyst and was found effective only when prepared from cells exhibiting active nitrogenase. It also restores the activity of modified Fe-protein from R. rubrum.

Acetylene↗
PubMed1990

[Experience with rapid molecular genetic diagnosis using the polymerase chain reaction].

The authors give an account of their experience with 1000 amplifications of DNA by the polymerase chain reaction for the prenatal diagnosis of cystic fibrosis. The method is demonstrated on examples of examinations of the informativity value and prenatal diagnosis in the first trimester of pregnancy in families with a 25% risk of cystic fibrosis, using J 3.11 (Msp I), met H (Msp I), KM 19 (Pst I), CS 7 (Hha I), Mp6d9 (Msp I), XV 2c (Taq I) probes. The authors summarize methodical check-up and safety measures to ensure the reliability of diagnoses made by the PCR method.

Cystic Fibrosis↗
PubMed1990

Cloning and sequence analysis of the human parathyroid hormone gene region.

A region of 50 kb around the human PTH gene was cloned and mapped by restriction analysis. Sequence analysis was performed and 3270bp determined, completing the sequence of the gene. The nucleotide sequence was analysed with regard to homology between human, bovine and rat PTH genes, and various potential cis-acting regulatory elements were identified. The gene region lacks an obvious CpG island. The PTH gene region in patients suffering from (pseudo)-hypoparathyroidism was investigated by Southern blotting. No detectable alteration in the fragment patterns was observed. Results of segregation analysis in families with affected individuals was inconclusive.

Animals↗
PubMed1990

Frequency of the delta F508 mutation and flanking marker haplotypes at the CF locus from 167 Czech families.

This study analyses distribution patterns of the delta F508 mutation of the cystic fibrosis transmembrane conductance regulator gene (CFTR) gene and the cystic fibrosis (CF)-linked marker loci MET, D7S23, D7S399, and D7S8 in a sample of 167 (116 complete) CF families from Bohemia and Moravia (Czechoslovakia). DNA typing was performed by polymerase chain reaction amplification, restriction analysis, and agarose or polyacrylamide gel electrophoresis. The frequency of the delta F508 mutation in this sample is 67% and the frequency of the B haplotype is 77.6% on CF chromosomes. Linkage disequilibrium was found between delta F508 and all markers tested.

Chromosome Deletion↗
PubMed1990

Distribution patterns of the delta F508 mutation in the CFTR gene of CF-linked marker haplotypes in the German population.

We have measured the frequency of the delta F508 mutation in the cystic fibrosis transmembrane conductance regulator (CFTR) gene and its association with cystic fibrosis (CF)-linked marker haplotypes in the German population. Based on the analysis of 400 CF chromosomes, the frequency of the delta F508 mutation is estimated to be 77.3%, the vast majority being associated with marker haplotype KM19-XV2c 2 1. Our data further suggest the presence of another frequent CF mutation associated with this marker haplotype.

Cystic Fibrosis↗
PubMed1990

Cystic fibrosis marker testing in Bohemia with polymerase chain reaction.

Conditions for assessing KM-19 probe detected by Pst-1 restriction fragment length polymorphism (RFLP) by means of polymerase chain reaction were provided. Computer controlled mechanical arm with waterbaths and cloned heat-stable DNA polymerase was used. Results of KM-19 allelic frequencies on 90 cystic fibrosis chromosomes are presented. Allele two frequency was -0.833.

Alleles↗
PubMed1990

[Sex determination using the polymerase chain reaction method for amplification of DNA segments on the X and Y chromosomes].

The authors tested the rapid and accurate prenatal and postnatal diagnosis of sex by the method of amplification of specific portions of DNA of sex chromosomes. To ensure a maximum reliability of the diagnosis the authors recommend combined examination of specific sequences from the heterochromatin region of the long arm of the Y chromosome (Yq) and from alphoid satellite sequences of DNA from the pericentromeric portion of chromosome X and Y (Xc and Yc). For further improvement of the reliability the authors recommend to digest the Yc amplification product obtained by means of restriction endonucleases Msp I, Eco Ri and Hini I. Correct assessment of the diagnosis was confirmed in all examined subjects (12) from DNA and chorium.

Female↗
PubMed1989

[Immunology in the aged].

On account of their katabolic status in general, elderly people show increasing involution of every organ and tissue. In addition to the decrease in functional vitality, we find morphologic reduction of highly differentiated cells. This process does also affect the immune system. Many diseases of old age (such as infections, malignomas, auto-immunopathies) seems to be brought about by immunodeficiency due to senescence. These diseases are promoted by the reduced production of antibodies against foreign antigens and by the decreased functions of T-suppressor subpopulations. On the other hand, we observe increasing auto-immunity, a rise of circulating immune complexes, and a higher tolerance towards alloantigenetic tissue. It is not easy to decide whether the pathologic immune status is the result of multimorbidity, or whether diseases of old age develop because of senile immunodeficiency. In this connection, our lacking knowledge regarding immunology in old age becomes obvious; moreover, the problem of answering these questions by means of systematic investigation has not yet been solved.

Aged↗
PubMed1987

Cytogenetic mapping of marker genes on the chromosome elements C and E of Drosophila pseudoobscura and D. subobscura.

Enzyme loci, visible marker genes and lambda-cloned DNA-sequences from a D. miranda library were mapped cytologically on the chromosome elements C and E of D. pseudoobscura and D. subobscura. New data are incorporated into the linkage maps of the two species. Homologous segments can now be localized in the polytene chromosomes with these markers. A comparison of the chromosome elements E of D. melanogaster and D. subobscura shows 12 conserved subsections which have been rearranged by paracentric inversions in the evolution of the two lineages.

Aldehyde Oxidase↗
PubMed1983

Bibliography of scanning electron microscopy application in Forensic Medicine.

The following bibliography of SEM - Application is largely oriented to medicolegal studies. Avoiding overlappings with criminalistic research papers were not always possible because the objects of inquiry as well as the forensic questions often are identical, such as investigations on hair or gunshot analyses. One important aspect could not be considered by us: the contact of principal medicolegal problems with those pathological, for example in structural changes of vessels after traumatization (Forensic Medicine: vital reaction - Pathology: thrombosis, hemostasis, wound healing). Publications have not been selected with regard to their relevance. Finally we have listed the problems and methods researched.

Bibliographies as Topic↗