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Biomedical subjects

W Wimmer

Publications and source records attributed to W Wimmer.

17 recordsLinked to original sources
PubMed2000

[Multi-channel data collection and visualization system for intramyocardial electrograms].

The aim of the project was to develop a multichannel data acquisition system for the recording and visualisation of intramyocardial electrograms (IEGM) from both the spontaneously beating and the artificially paced heart. Signal processing comprises multi-step amplification, filtering (0.05-800 Hz), and AD conversion (12 Bit max. 6.25 kHz). IEGMs can be obtained either in unipolar or bipolar mode. Stimulation of the heart is achieved by an incorporated programmable dual-chamber pacemaker that can be selectively switched to the input channels. A LabView-based graphical user interface permits the programming of all system parameters via a microcontroller, and supports data acquisition and visualisation. The system can be used in animal experiments to monitor the spread of excitation across the heart, to measure propagation velocity, or to measure the impact of drugs and pathological changes on the morphology of IEGMs.

Computer Graphics↗
PubMed1999

Initiation of an Aquaculture of Sponges for the Sustainable Production of Bioactive Metabolites in Open Systems: Example, Geodia cydonium.

Among Metazoa, sponges (phylum Porifera) are the richest source for different bioactive compounds. The availability of the raw material is, however, restricted. To obtain enough of the bioactive compounds for application in human therapy, sponges have to be cultured in in vitro systems. One technique for the establishment of a long-term cell culture from sponges has recently been elaborated. Here, we present a procedure to cultivate tissue samples from sponges in an open system. The species Geodia cydonium, which produces bioactive compounds, has been selected. Tissue samples of approximately 10 g were attached to the bottoms of cultivation trays. After 2 to 3 days, the tissue samples formed a robust contact with the metal support. Subsequently, sets of trays, called tray batteries, either remained in huge aquaria at the Center for Marine Research or were transferred to the vicinity of a fish and mussel farm. The growth rates of the samples remained unchanged within the first month; however, after 3 and 6 months, they increased to 147% and 189%, respectively. In parallel, extracts were prepared from the tissue samples and tested for cytotoxicity in a mouse lymphoma cell assay system. Extracts from cultured tissue initially had a low inhibitory potency; however, after cultivation for 3 or 6 months, values comparable to those of extracts from sponges taken from the biotope were found. In addition, a molecular marker was applied to document the response (health state) of the tissue and the identity of the material in culture. The CD63 molecule was chosen because the expression of this molecule in mammalian systems changes with the age of the animals. The corresponding complementary DNA was isolated from Geodia cydonium. With this probe, the level of expression in cultured tissue samples decreased immediately after starting cultivation; after a cultivation period of 6 months, however, values were similar to those found in controls. These data show that sponge species that produce bioactive compounds can be cultivated in open systems, in which they retain their potency to produce bioactive compounds as well as their health state.

Journal Article↗
PubMed1999

Origin of the integrin-mediated signal transduction. Functional studies with cell cultures from the sponge Suberites domuncula.

Sponges (phylum Porifera) represent the phylogenetically oldest metazoan animals. Recently, from the marine sponge Geodia cydonium a first cDNA encoding a putative integrin receptor molecule was isolated. In the present study basic functional experiments have been conducted to test the hypothesis that in sponges integrin polypeptides also function as adhesion molecules and as outside-in signaling molecules. The sponge Suberites domuncula has been used for the experiments because from this sponge only has a cell culture been established. Here we report that aggregation factor (AF)-mediated cell-cell adhesion is blocked by the RGDS peptide which is known to interact with beta integrin. Both RGDS and AF were found to stimulate DNA synthesis within 24 h. The beta subunit of the integrin receptor was cloned from S. domuncula; the estimated 91-kDa molecule comprises the characteristic signatures. Evolutionary conservation of the beta integrin was assessed by comparison with corresponding beta integrin subunits from evolutionary higher metazoan taxa. Addition of RGDS or of AF to isolated cells of S. domuncula causes a rapid (within 1-2 min) increase in the intracellular Ca2+ concentration which is further augmented in the presence of Ca2+. Furthermore, incubation of the cells with RGDS or AF causes an activation of the GTP-binding protein Ras. In addition it is shown that after a prolonged incubation of the cells with RGDS and AF the expression of the genes coding for Ras and for calmodulin is upregulated. These results suggest that the integrin receptor functions in the sponge system not only as adhesion molecule but also as a molecule involved in outside-in signaling.

Amino Acid Sequence↗
PubMed1999

Increased expression of integrin and receptor tyrosine kinase genes during autograft fusion in the sponge Geodia cydonium.

Recently cDNAs coding for cell surface molecules have been isolated from sponges. The molecules for alpha-integrin, galectin, and receptor tyrosine kinase (RTK), obtained from the marine sponge, Geodia cydonium, have been described earlier. In the present study also the cDNA for one putative beta-integrin has been identified from G. cydonium. The deduced aa sequence comprises the characteristic signatures, found in other metazoan beta-integrin molecules; the estimated size is 95,215 Da. To obtain first insights into the molecular events which proceed during autograft fusion, the expressions of these genes were determined on transcriptional and translational level. The cDNAs as well as antibodies raised against the recombinant sponge proteins alpha-integrin, RTK and galectin were used and Northern blot experiments and immunocytochemical analyses have been performed. The results show that transcription of the two subunits of an integrin receptor as well as of the RTK are strongly upregulated after grafting; levels of > 10-fold have been determined in the fusion zone of the grafts after a 10 days incubation. Immunofluorescence studies of sections through the fusion zone support these data. In contrast the transcription of the gene encoding galectin is drastically downregulated after grafting. In a parallel series of experiments the level of the heat-shock protein-70 was determined and it was found that it remained unchanged after grafting. We conclude that integrin subunits and the RTK molecule are involved in self-self recognition of sponge.

Amino Acid Sequence↗
PubMed1990

[How to expose fraudulent expert witnesses].

In our courtrooms you can meet, up to this day, experts of dubious qualities if not mere shams and deceivers. They are found in all sciences, but also in pseudo-sciences as paramedicine and parapsychology. In any case such expert pretenders must be exposed by the judge to prevent dangerous miscarriage of justice. Examples are given how to unmask the fraudulent rascals.

Criminal Law↗
PubMed1984

[3-Methylhistidine as a parameter for the determination of muscle proteolysis in the post-stress syndrome and in diabetes mellitus].

The renal excretion of 3-methylhistidine was measured in healthy human volunteers under different diets. The excretion of 3-methylhistidine and total nitrogen was increased in 8 surgical patients. These findings are referred to an increased proteolysis mainly in the skeletal muscle. In four insulin-dependent diabetic patients (IDDM) the excretion of 3-methylhistidine into urine was increased only when referred to body weight. The interpretation of the 3-methylhistidine/creatinin ratio is discussed. In diabetic patients the total nitrogen excretion seems to be a better parameter for protein turnover than 3-methylhistidine. The data suggest that 3-methylhistidine excretion into urine is a suitable parameter for the determination of muscle protein turnover.

Adult↗
PubMed1980

[Methods of medical outsiders from the lawyer's point of view (author's transl)].

As a consequence of the widespread humbug in Medicine today the number of law suits against medical outsiders causing damage to patients is visibly increasing. Quackery is unmasked by typical features common to nearly all occult sciences. In cases of failure or doing harm to patients medical outsiders have to face indictment more than scientifically treating physicians. Sometimes there is even suspicion of deliberate cheating, if not mental disorder. Legislation is urged to bring to an end this humiliating form of quackery.

Complementary Therapies↗
PubMed1976

[Extirpation of nasopharyngeal fibromas after selective preoperative angiographic embolization].

The gross amount of bleeding during surgical removal of nasopharyngeal angiofibromas is feared. An excellent method to reduce this amount is the preoperative selective embolization of the feeding vessels of these tumors under angiographic control. The advances in selective angiography of the branches of the external carotid artery by femoral catheterization make it possible to applicate Gelfoam emboli in the very arteries which are to be embolized. There is a case report about two young men who have been pretreated in this manner. The intraoperative bleeding was minimal.

Embolization, Therapeutic↗