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B Niemeyer

Publications and source records attributed to B Niemeyer.

8 recordsLinked to original sources
PubMed2006

Glycolipids from a colloid chemical point of view.

Glycolipids are a group of compounds with a broad range of applications. Two types of glycolipids (alkylpolyglycosides and gangliosides) were examined with regard to their physicochemical properties. Despite their structural differences, they have in common that they are amphiphilic molecules and able to aggregate to form monolayers, bilayers, micelles, lyothropic mesophases or vesicles. The structures of glycolipid micelles were investigated by different experimental techniques in addition to molecular dynamic simulations. The knowledge of the physicochemical properties of gangliosides enables a better understanding of their biological functions. Structural features were obtained for the monosialogangliosides GM1, GM2 and GT1b from bovine brain by means of mass spectrometry. Further the aggregation behaviour was determined by small-angle neutron and dynamic light scattering experiments. Interaction studies of these compounds were carried out by means of surface plasmon resonance using gangliosides incorporated liposomes. They were used as model membranes that interact with the lectins WGA, RCA and HPA. The interaction of lectins immobilized to a modified silicon surface was investigated by in-situ ellipsometry.

Animals↗
PubMed2005

Development of a basic procedure to design sorption processes.

The intention of this work is to offer, within the shortest time, an appropriate sorption separation process for almost any odour problem. The development is based on the preparation and characterisation of new adsorbents, the strategy for the selection of the best adsorbent, the process engineering and the choice of a suitable regeneration procedure. In this context a new method for the characterisation of the adsorbents - the adsorption profile analysis - was developed. The classification of the adsorbents was carried out by means of a cluster analysis, which simplifies the selection of the most suitable adsorbent for a particular problem. The physical and chemical behaviour of silica-adsorbents could be tailored by silanisation of the surfaces. Methods for the determination of process engineering parameters were developed, established and used. Adsorption kinetics and isotherms were determined with a magnetic adsorption balance. In a laboratory-scale fixed bed adsorber, breakthrough curves of different support materials were investigated and compared. For the investigations of different regeneration procedures, four innovative methods were employed: microwave desorption, ultrasonic desorption, ultrasonic-water desorption and extraction with water. Of the four desorption methods examined, microwave desorption and ultrasonic-water desorption demonstrated the best results.

Adsorption↗
PubMed2001

Preparation and evaluation of Ricinus communis agglutinin affinity adsorbents using polymeric supports.

A practicable and efficient procedure for preparation of Ricinus communis agglutinin (RCA) affinity adsorbents has been developed. For immobilization of RCA two different polymer-based supports, Toyopearl and TSKgel (TosoHaas), were used. RCA has been successfully immobilized onto these supports with amounts of coupled ligand between 15 and 23 mg/g dry support and corresponding coupling yields of 69-93% (w/w). The prepared affinity adsorbents were characterized concerning their binding capacity for the glycoprotein asialofetuin (ASF) and accessibility of the ligand binding sites. The high accessibility of 80% showed that steric hindrance was negligible at the present ligand density. RCA-Toyopearl was successfully applied in affinity chromatography of glycoproteins indicating its high specificity. A long-term stability test proved no change in capacity for a period of at least 12 months. High-performance affinity chromatography (HPLAC) was carried out using RCA-TSKgel. Experimental results showed that the prepared adsorbents are suitable for selective separation of glycoproteins and oligosaccharides and therefore can be used for investigations of adsorption characteristics of glycoconjugates and for laboratory-scale preparations.

Ricinus communis↗
PubMed1995

Regulation of PLC-mediated signalling in vivo by CDP-diacylglycerol synthase.

CDP-diacylglycerol synthase (CDS) is an enzyme required for the regeneration of the signalling molecule phosphatidylinositol-4,5-bisphosphate (PtdlnsP2) from phosphatidic acid. A photo-receptor cell-specific isoform of CDS from Drosophila is a key regulator of phototransduction, a G-protein-coupled signalling cascade mediated by phospholipase C. cds mutants cannot sustain a light-activated current as a result of depletion of PtdlnsP2. Overexpression of CDS increases the amplitude of the light response, demonstrating that availability of PtdlnsP2 is a determinant in the gain of this pathway. cds mutants undergo light-dependent retinal degeneration which can be suppressed by a mutation in phospholipase C. Thus, enzymes involved in PtdlnsP2 metabolism regulate phosphoinositide-mediated signalling cascades in vivo.

Amino Acid Sequence↗
PubMed1995

A novel protein encoded by the InaD gene regulates recovery of visual transduction in Drosophila.

InaDp215 is a point mutation that affects photoreceptor function in Drosophila. To understand the molecular basis of the defect, we isolated the InaD gene and found it encodes a photoreceptor-specific polypeptide of 674 residues. Within its sequence are two repeats that share remarkable homology with a family of cytoskeleton-associated proteins that are involved in signal transduction. Patch-clamp recordings from isolated photoreceptor cells of InaDp215 show a slow deactivation of the light-induced current. This defective deactivation of InaD appears dependent on calcium influx; removal of extracellular calcium masks its abnormal phenotype. Moreover, InaD photoreceptors show increases sensitivity to dim light. We propose that InaD is involved in the negative feedback regulation of the light-activated signaling cascade in Drosophila photoreceptors.

Amino Acid Sequence↗
PubMed1992

High-dose intravenous immune globulin therapy for hyperbilirubinemia caused by Rh hemolytic disease.

We conducted a multicenter controlled trial to test the hypothesis that high-dose intravenous immune globulin (HDivIG) therapy can modulate bilirubin production and reduce the frequency of exchange transfusions in newborn infants with Rh hemolytic disease. Thirty-four patients with Rh incompatibility proved by positive direct antiglobulin test (Coombs test) results were randomly assigned to receive conventional treatment including phototherapy, with or without additional HDivIG therapy at 500 mg/kg given for a 2-hour period as soon as the diagnosis was established. Exchange transfusions were performed if serum bilirubin concentrations exceeded the modified curves of Polácek by more than 2 mg/dl. Two patients were excluded because of protocol violations. The results in 32 infants were analyzed. In the HDivIG group, 2 (12.5%) of 16 children required exchange transfusions, whereas it became necessary in 11 (69%) of 16 children in the control group (p less than 0.005). Bilirubin levels in the HDivIG group were lower despite reduced frequency of exchange transfusions. No side effects of HDivIG treatment were observed. We conclude that HDivIG therapy by a yet unknown mechanism reduces serum bilirubin levels and the need for blood exchange transfusions in children with Rh hemolytic disease.

Anemia↗
PubMedDate not supplied

Disturbing GTP-binding protein function through microinjection into the visual cell of Limulus.

We have tested the action of three agents microinjected into the ventral nerve photoreceptor of Limulus on the electrical response to dim light. 1. A monoclonal antibody (mAb 4A) against the G alpha subunit of frog transducin reduces the size of the receptor current to 60%, suggesting an interaction with G alpha in the Limulus photoreceptor. 2. Injection of Clostridium botulinum ADP-ribosyltransferase C3 reduces the size to 46%; latency is not affected. The results imply that small GTP-binding proteins play a functional role in photoreception of invertebrates. 3. Injection of GDP-beta-S reduces dose-dependently the size of the receptor current to 15% and prolongs the latency to 200%, presumably by reducing number and rate of G-protein activations.

Animals↗