Biomedical subjects

H Dammann

Publications and source records attributed to H Dammann.

3 recordsLinked to original sources

PubMed1991

Ca2+/calmodulin-binding proteins in Dictyostelium discoideum.

We have initiated a systematic study of Ca2+/calmodulin-regulated enzymes in the cellular slime mold Dictyostelium discoideum. Using 125I-labelled D. discoideum calmodulin (CaM) as a functional probe, several Ca2+/CaM-binding proteins were detected in crude cell lysates. Proteins with apparent molecular weights of 22 kDa and 78-80 kDa, respectively, were found in the soluble fraction. In addition, membrane-bound high molecular weight CaM-binding proteins were identified. Binding of CaM to all of the proteins required the presence of Ca2+ ions and competed efficiently with nonradioactive CaM from both Dictyostelium and bovine brain. The CaM antagonists melittin, W-7 and R24571 inhibited CaM binding. With a functional cloning approach, we previously obtained cDNA clones by screening a lambda gt11 lysogen expression library; in this paper, we report the analysis of CaM-binding activity by one of the recombinant cDNA clones in Escherichia coli. When rabbit antiserum was raised against it, the antiserum recognized a 78-80-kDa protein in Dictyostelium extracts which comigrated on SDS-polyacrylamide gels with 78-80-kDa CaM-binding activity.

Animals↗

PubMed1991

[Ranitidine in the therapy and prevention of NSAR-induced (non-steroidal anti-rheumatic agents) gastroduodenal lesions in patients with rheumatism].

178 patients with various rheumatic disorders who had been treated with non-steroidal anti-inflammatory drugs (NSAID) for at least 32 months, were enrolled in this open trial. Entry criteria were both the presence of endoscopic lesions in gastric and/or duodenal mucosa as well as dyspeptic symptoms. All patients were treated with ranitidine 150 mg bid for 4 weeks; 127 of them continued to take their original medication. Only in a small subgroup of 21 patients the NSAIDs were withdrawn. Mean gastric lesions scores averaged at entry in both treatment groups 2.2 and 2.0; the corresponding duodenal values were 2.2 and 2.6. After 4 weeks therapy a significant reduction of the mean gastric and duodenal damaging scores was observed (p less than 0.05). In addition, a marked symptomatic relief occurred. In the subsequent prophylactic trial 98 patients could be followed for 3 months and 59 patients for at least 6 months. 44 patients (3 months) and 36 patients (6 months) received in addition to their antirheumatic medication ranitidine 150 mg bid, whereas 54 patients (3 months) and 23 patients (6 months) were without any antiulcer therapy. The calculated relapse rates within 6 months were in the presence of ranitidine only 12% and without ranitidine 63% (p less than 0.05). Our data emphasize the efficacy of H2-receptor antagonist both in the therapy as well as in the prophylaxis of NSAID-induced lesions in the upper GI-tract.

Anti-Inflammatory Agents, Non-Steroidal↗

PubMed1990

Prophage lambda libraries for isolating cDNA clones by functional screening.

Isolation of cDNA clones from lambda gt11 phage libraries by functional screening is limited by the low amount of lacZ-cDNA-encoded fusion protein synthesized in an isolated phage plaque. The amount of specific cDNA-encoded protein can be significantly enhanced by expression in bacterial colonies rather than phage plaques. Escherichia coli was lysogenized with a lambda gt11 cDNA expression library from Dictyostelium discoideum. Bacteria were selected for the presence of the lambda gt11 prophage by elimination of nonlysogenic parental cells with a lambda cI phage. The usefulness of the lysogen library was demonstrated by immuno-screening and functional screening with two different radiolabeled ligands. cDNA clones encoding a well-characterized D. discoideum protein, the regulatory subunit of the cAMP-dependent protein kinase, were isolated by screening the lysogen library with antibodies. Clones encoding this protein could also be identified by functional screening with [3H]cAMP, demonstrating that the limit of detection of positive clones by ligand screening is at least an order of magnitude lower for the lysogen library than for the corresponding phage library. We have subsequently used the lysogen library to isolate cDNA clones encoding calmodulin-binding protein(s) from D. discoideum by functional screening with [125I]calmodulin. For these clones, screening of the corresponding phage library had previously been found unsuccessful.

Bacteriophage lambda↗