[Direct thrombin antagonists]. / Direkte Thrombinantagonisten.

BACKGROUND: Inhibiting thrombin as a key enzyme of the coagulation cascade is therapeutically useful in thromboembolic diseases. In coronary thrombosis, direct thrombin inhibitors promise to be useful for an efficacious therapy. Hirudin and recombinant or synthetic mimetics like hirulog, argatroban and melagatran have proven their efficacy in clinical studies. CONCLUSION: Therapy with direct thrombin inhibitors such as hirudin and analogous substances reduces coronary events. Moreover, the agents are useful for therapy of thromboembolic diseases, especially in the case of heparin induced thrombocytopenia type II.

A role of the cryptic gene in the correct establishment of the left-right axis.

During vertebrate embryogenesis, a left-right axis is established. The heart, associated vessels and inner organs adopt asymmetric spatial arrangements and morphologies. Secreted growth factors of the TGF-beta family, including nodal, lefty-1 and lefty-2, play crucial roles in establishing left-right asymmetries [1] [2] [3]. In zebrafish, nodal signalling requires the presence of one-eyed pinhead (oep), a member of the EGF-CFC family of membrane-associated proteins [4]. We have generated a mutant allele of cryptic, a mouse EGF-CFC gene [5]. Homozygous cryptic mutants developed to birth, but the majority died during the first week of life because of complex cardiac malformations such as malpositioning of the great arteries, and atrial-ventricular septal defects. Moreover, laterality defects, including right isomerism of the lungs, right or left positioning of the stomach and splenic hypoplasia were observed. Nodal gene expression in the node was initiated in cryptic mutant mice, but neither nodal, lefty-2 nor Pitx2 were expressed in the left lateral plate mesoderm. The laterality defects observed in cryptic(-/-) mice resemble those of mice lacking the type IIB activin receptor or the homeobox-containing factor Pitx2 [6] [7] [8] [9], and are reminiscent of the human asplenic syndrome [10]. Our results provide genetic evidence for a role of cryptic in the signalling cascade that determines left-right asymmetry.

Moesin: a cell membrane protein linked with susceptibility to measles virus infection.

Measles virus is a highly contagious virus causing acute and persistent diseases in man, the receptor of which is still not well characterized. We have isolated a monoclonal antibody (mAb), designated mAb 119, which specifically inhibits measles virus infection of susceptible cell lines in a dose-dependent manner. This antibody precipitates a protein with an apparent molecular mass of 75 kDa from 125I surface-labeled cells and its epitope is present on human peripheral blood mononuclear cells, human cell lines, and the African green monkey cell line Vero. Affinity chromatography of detergent-solubilized cell membrane proteins over a Sepharose column with covalently bound mAb 119 led to the partial purification of the 75-kDa protein. Preincubation of measles virus with this affinity-purified protein inhibited measles virus infection dose dependently. Amino acid microsequencing of this protein revealed its identity with the human membrane-organizing extension spike protein moesin, a protein intra- and extracellularly associated with the plasma membrane of cells. Subsequently, an antibody raised against purified moesin (mAb 38/87) was also found to specifically inhibit measles virus infection of susceptible cells and confirmed our data obtained with mAb 119. Our data suggest that moesin is acting as a receptor for measles virus.

Structure and localization on the X chromosome of the gene coding for the human filopodial protein moesin (MSN).

Moesin is a member of a recently discovered family of closely related proteins that includes ezrin, radixin, and merlin. It is widely expressed in different tissues and cells and has been localized to filopodia and other membranous protrusions that are important for cell-cell recognition and signaling and cell movement. Here, we have localized the coding gene (MSN) to Xq11.2-q12 by Southern and Western blot analyses of Chinese hamster x human somatic cell hybrids and by fluorescence chromosomal in situ hybridization. Moesin-like sequences were identified on chromosomes 5 and 6. The murine Msn locus was mapped to the X chromosome as well by studying a rodent x mouse hybrid panel. The structure of the human moesin gene has been determined. The 12 exons are distributed over > 30 kb, and the exon/intron junctions demarcate individual highly conserved domains. Primer extension analysis revealed two major start transcription sites, 184 and 133 bp upstream of the initiation codon. The 5'-flanking region is GC-rich, lacks a TATA box, and contains four SP1 and one AP1 binding sites.

Cloning and sequencing of porcine moesin and radixin cDNA and identification of highly conserved domains.

The full length cDNA of porcine moesin and radixin have been cloned and sequenced. Comparison of the closely related sequences of human, murine and porcine moesin, ezrin and radixin with a protein from Echinococcus multilocularis, an evolutionarily quite distant human parasite, reveals several highly invariant domains in the aminoterminal and carboxyterminal regions. Most of these conserved domains are clustered around tyrosine residues that are putative phosphorylation sites for tyrosine phosphokinases.

[New diagnostic methods--ultrasound and clinico-chemical procedures in diagnosis of ischemia]. / Neue diagnostische Methoden--sonographische und klinisch-chemische Verfahren der Ischämie-Diagnostik.

Stress-echocardiography represents a new non-invasive, alternative approach in the assessment of patients with coronary artery disease. By means of dynamic or pharmacological stress or by atrial pacing regional wall motion abnormalities can be induced, which can be identified by 2D-echocardiography. Beyond the indirect detection of ischemia this approach allows a better quantification of the amount of ischemia and of global LV function, which is advantageous compared to stress ECG recording or myocardial scintigraphy. Disadvantageous is however, the subjective reading of the echo itself. In experienced hands stress-echocardiography has proven to be as sensitive and specific as myocardial scintigraphy. Recently, in addition the diagnostic potential of myocardial cell injury has been improved by the detection of specific antibodies versus Troponin T. In comparison with conventional biochemical markers of myocardial cell necrosis Troponin T analysis has been proven to be superior in postoperative or traumatic cardiac damage or in the setting of acute myocardial infarction. In this situation the time window is improved by an earlier rise compared to CK and a longer detection rate compared to lactate dehydrogenase.

Moesin: a member of the protein 4.1-talin-ezrin family of proteins.

Moesin (membrane-organizing extension spike protein, pronounced mó ez in) has previously been isolated from bovine uterus and characterized as a possible receptor protein for heparan sulfate. We now have cloned and sequenced its complete cDNA, which represents a single 4.2-kilobase mRNA encoding a protein of 577 amino acids. It contains no apparent signal peptide or transmembrane domain. In addition, the protein shows significant sequence identity (72%) to ezrin (cytovillin, p81), as well as similarity to protein 4.1 and talin. All of the latter proteins have been postulated to serve as structural links between the plasma membrane and the cytoskeleton. A similar role for moesin is implied by structure and domain predictions derived from the cDNA-deduced peptide sequence. Furthermore, our data indicate that moesin is identical to the 77-kDa band that copurifies with ezrin in its isolation from human placenta [Bretscher, A. (1989) J. Cell Biol. 108, 921-930].

A heparin-binding protein involved in inhibition of smooth-muscle cell proliferation.

A heparin-binding protein was isolated from bovine uteri and purified to homogeneity. This protein appears as a double band of approx. 78 kDa in SDS/polyacrylamide-gel electrophoresis and has an isoelectric point of 5.2. The binding of heparin to this protein is saturable. No other glycosaminoglycan from mammalian tissue, such as hyaluronic acid, chondroitin sulphate, dermatan sulphate or keratan sulphate, binds to the 78 kDa protein. Dextran sulphate binds in a non-saturable fashion. Certain heparan sulphate polysaccharide structures are required for binding to the 78 kDa protein. Some proteoheparan sulphates, such as endothelial cell-surface proteoheparan sulphate, show only weak interaction with the 78 kDa protein in contrast with a basement-membrane proteoheparan sulphate from HR-9 cells. Antibodies against the 78 kDa protein inhibit binding of proteoheparan [35S]sulphate from basement membranes to smooth-muscle cells. Conventional antibodies, Fab fragments and some monoclonal antibodies, inhibit smooth-muscle cell proliferation in a similar range as that observed for heparin. The protein was detected in a variety of tissues and cells but not in blood cells. A possible role of this protein as a receptor for heparin or heparan sulphate and its function in the control of the arterial wall structure are discussed.