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Biomedical subjects

A Voigt

Publications and source records attributed to A Voigt.

At least 37 records · Page 2Linked to original sources
PubMed1996

Glycoprotein B (gB) of pseudorabies virus interacts specifically with the glycosaminoglycan heparin.

We have previously shown that the pseudorabies virus (PrV) glycoproteins gB and gC (former PrV-gII and PrV-gIII) exhibit heparin-binding properties. While PrV-gC functions as the major adsorption protein, the biological role of the heparin-binding properties of PrV-gB are not understood. We used a gC-deleted PrV-mutant, PrV (dlg92/dltk), to analyse the heparin-binding properties of PrV-gB and the biological role of the PrV-gB-protein in adsorption. PrV-gB was the only glycoprotein of this vaccine strain binding to immobilised heparin in in vitro assays. Presence of the gC-protein was not necessary for the interaction of gB with heparin. Soluble heparin also interfered with adsorption of this mutant virus to a similar extent as it blocked adsorption of wild-type PrV (Ka), but it had only a minor inhibitory effect on infectivity of the mutant strain. These results show that PrV-gB interacts specifically with immobilized heparin and heparin-like structures on the cell surface, but this interaction is not required for a productive infection.

Adsorption↗
PubMed1996

The effect of erythropoietin on lactate, pyruvate and excess lactate under physical exercise in dialysis patients.

To investigate EPO-induced increase of hemoglobin on energy metabolism plasma concentrations of lactate (L), pyruvate (P) and excess lactate (XL) were determined in ten dialysis patients at rest, immediately after 6 minutes of ergometric exercise as well as after recovery for 15 and 30 min. The investigations were performed before EPO-therapy at a mean Hb = 7.5 +/- 0.9 g/dl and under EPO-therapy at a mean Hb = 10.0 +/- 0.6 g/dl and at a mean Hb = 11.9 +/- 0.8 g/dl. Ten healthy subjects were subjected to the same investigation at Hb = 14.7 +/- 1.1 g/dl. There was a significant rise of L and XL in all patient groups under ergometric exercise. The increase of hemoglobin from 7.5 g/dl to 10.0 g/dl led to significantly (p < 0.01) lower L and XL concentrations immediately after exercise (L = 4.62 vs 3.23 mmol/l, XL = 2.37 vs 1.38 mmol/l). The further decrease of the mean L and XL values (L = 2.88 mmol/l, XL = 1.05 mmol/l) associated with the rise of hemoglobin to 11.9 g/dl could not be confirmed statistically. In contrast to all patient groups, there was no significant rise in XL in the healthy control subjects under physical exercise. The present results make it evident that patients with renal anemia react even to light physical exercise with pronounced tissue hypoxia in contrast to healthy subjects. The increase of the hemoglobin content under the EPO-therapy leads to a marked reduction of the tissue hypoxia and consequently of anaerobic energy production. A further rise of the hemoglobin content above and beyond 10.5 g/dl will have an additional positive effect on oxygen supply only in occasional cases. The comparison with healthy subjects shows that despite a very large degree of normalization of the hemoglobin content, no normalization of energy metabolism can be attained.

Anaerobic Threshold↗
PubMed1995

Characterisation of cell movement by impedance measurement on fibroblasts grown on perforated Si-membranes.

Mouse fibroblasts grown on perforated Si-membranes (pore diameter approximately 10 microns have been studied to clarify cell locomotive ability. The cell motility was microscopically monitored by a time-lapse video system and, simultaneously, the impedance of the growing cells was measured every 5 s. The correlations between observed cell activities and measured impedance events are discussed and classified. The method is sensitive and allows discrimination between signals arising from translocation of single cells and those arising from filopodia activities. Both cell and filopodia motion could be detected. Designs of microdevices fabricated in semiconductor technology are presented.

3T3 Cells↗
PubMed1995

Cellular receptor structures for pseudorabies virus are blocked by antithrombin III.

Pseudorabies virus (PrV), an alphaherpesvirus of swine, uses cellular heparan sulfate residues as a receptor for attachment. Interaction of the virus with its receptor is mediated by the envelope glycoprotein C (PrV-gC), a protein with heparin-binding properties. We have previously shown that a region of this protein shows structural similarities to the high-affinity heparin-binding site of the serum protease-inhibitor antithrombin III (ATII). In this publication, we describe the effect of ATIII on interaction of PrV with its cellular receptor. ATIII bound specifically to heparan sulfate residues on the surface of herpesvirus-permissive RK13 cells. Binding of ATIII to RK13 cells interfered with adsorption of radioactively labelled PrV to these cells. Enzymatic treatment using heparinase I (E.C. 4.2.2.7) removed the receptor for PrV as well as the receptor for ATIII. Since amino acids 130-137 of the high affinity heparin-binding site of ATIII show structural similarities to amino acids 134-141 of PrV-gC, both sequences were synthesized as synthetic peptides. Although interaction of the peptide derived from ATIII with heparin was significantly stronger, both peptides interacted specifically with heparin in assays in vitro. These results suggest that PrV and ATIII interact with the same structure on the cellular surface.

Amino Acid Sequence↗
PubMed1995

[New aspects in the treatment of complete and isolated diaphyseal fracture of the forearm in childhood].

From 1984 to 1992 153 children were treated at the pediatric surgical department of the University of Mainz, of whom 19 had fractures of the radius, 9 of the ulna and 125 had a combination of both in the diaphysis of the forearm. Factors like patient's age, type of fracture and therapeutic methods were analyzed. One hundred and forty-one children were treated conservatively, 12 by operation. One hundred and one of these patients were healthy, when discharged (about 8 weeks after accident). Follow-up was possible in 69 cases. We found that occasional a remaining dislocation angle does not impair function: in 65 cases the result was "good" and "very good", but only "moderate" in 4 cases. These 4 children had been treated conservatively by reposition and plaster cast; 2 of these 4 children showed bone reconstruction without dislocation. Twenty-two of the 56 X-ray follow-up's showed persisting dislocation. To prevent functional problems (2 of our cases) it is essential to obtain a very exact reposition of diaphyseal forearm fractures. Therefore we would recommend a more generous indication for operation, preferably using elastic-stable Nancy pins.

Adolescent↗
PubMed1995

Adhesion of leucocytes to microscope slides as influenced by electrostatic interaction.

The adhesion of leucocytes to standard microscope slides is low, which severely limits the cell recovery in cytological preparations on such slides. We coated the slides with various polycations with the aim of achieving an electrostatic surface charge which would increase the cell adhesion but would still avoid cell disruption. The adhesion of leucocytes from a K562 myeloid cell suspension and from cerebrospinal fluid was measured on standard slides made of glass and of oxidized polystyrene, and on slides coated with several chemically different cationic polymers. The electrostatic surface charge and the surface tension of these matrices were determined. We found the cell adhesion to be significantly higher on the matrices with a more attractive zeta potential and not to be measurably influenced by the surface tension of the matrices. The results help to improve the cytological preparation technique, especially for suspensions with a low cell content.

Analysis of Variance↗
PubMed1994

Radio-frequency microtools for particle and liver cell manipulation.

Single particles can be manipulated by applying high frequencies to ultramicro electrode arrays fabricated on planar structures. Heat production can be reduced to the extent that intense electric fields can be applied even to unmodified cell culture media. Animal cells grow normally in the high field (up to 100 kV/m) between such continuously energized multielectrodes. As with laser tweezers [1-3], this technique can capture particles and cells in field traps, generate linear movement, and permit cell cultivation. It can also produce micropatterns of pH gradients, field-cast objects, and control cell adhesion. These microtools may be combined to develop cell separators, microsensors, and controlled-biocompatibility surfaces.

Animals↗
PubMed1993

A peptide-model for the heparin-binding property of pseudorabies virus glycoprotein III.

The pseudorabies virus glycoprotein III (PrV-gIII) has been identified previously as the major viral component binding to a heparin-like receptor on the surface of target cells. The amino acid sequence of gIII contains three regions corresponding to consensus sequences for heparin binding. A synthetic peptide corresponding to amino acids 134 to 141 of PrV-gIII bound heparin in a dot blot assay. In contrast, a synthetic peptide derived from amino acids 290-299 of PrV-gIII did not bind heparin. We therefore conclude that the region containing amino acid 134-141 is involved in binding to the heparin-like cellular receptor.

Amino Acid Sequence↗
PubMed1993

Monoclonal antibodies against neuroblastoma. Production and preliminary characterization of their specificity.

Neuroblastoma (NB) is a common childhood tumor that originates from neuroblasts of the neural crest. In this paper we will describe the production of murine monoclonal antibodies (mAbs) to human NB cell lines. The hybridomas were selected by ELISA and immunofluorescence for antibody binding to multiple human neuroblastoma cultured cell lines, but not to hematopoietic cells and leukemic cells. The mAbs were characterized in terms of their ability to bind to human cell lines and tissues. The IgG2a and IgG2b mAbs may prove useful in the diagnosis of therapy of neuroblastoma.

Animals↗
PubMed1990

Use of a computerized closed-loop sodium nitroprusside titration system for antihypertensive treatment after open heart surgery.

This study evaluates the clinical applicability of administering sodium nitroprusside by a closed-loop titration system compared with a manually adjusted system. The mean arterial pressure (MAP) was registered every 10 and 30 sec during the first 150 min after open heart surgery in 20 patients (group 1: computer regulation) and in ten patients (group 2: manual regulation). The results (16,343 and 2,912 data points in groups 1 and 2, respectively), were then analyzed in four time frames and five pressure ranges to indicate clinical efficacy. Sixty percent of the measured MAP in both groups was within the desired +/- 10% during the first 10 min. Thereafter until the end of observation, the MAP was maintained within +/- 10% of the desired set-point 90% of the time in group 1 vs. 60% of the time in group 2. One percent and 11% of data points were +/- 20% from the set-point in groups 1 and 2, respectively (p less than .05, chi-square test). The computer-assisted therapy provided better control of MAP, was safe to use, and helped to reduce nursing demands.

Adult↗
PubMed1989

[Monoclonal antibodies in research and clinical medicine].

The development of the hybridoma technology by G. Köhler and C. Milstein in 1975 enables us to produce monoclonal antibodies with desired specificities for the application in many branches of the biological sciences. The following article describes the technique of hybridizing spleen cells from immunized mice with myeloma cells. The resulting hybridoma produce monoclonal antibodies which have been applied in a wide variety of immunoassay methods. They are also useful in the structural analysis and quantification of antigens and have many applications as diagnostic and therapeutic agents for different tumors. There are already several reports of trials in which monoclonal antibodies eliminate neoplastic cells from bone marrow.

Antibodies, Monoclonal↗
PubMed1986

Electrophoretic mobility of human erythrocytes. On the applicability of the charged layer model.

The limitations of previous linear electrokinetic theories are discussed. A special model of the surface charge distribution, based on the minimum condition of the interfacial electrostatic free energy, is introduced. The model describes the electrophoretic mobility, taking into account the electroosmotic flow through the surface macromolecular layer and the surface conductivity. This nonlinear electrophoretic theory describes experimental data obtained with human erythrocytes. Numerical results for an uniformly distributed space charge are also presented.

Cell Movement↗
PubMed1983

Charge distribution within cell surface coats of single and interacting surfaces--a minimum free electrostatic energy approach. Conclusions for electrophoretic mobility measurements.

The fixed charge distribution in a cell surface coat model was calculated using a variational approach based on the minimum of electrostatic free energy. The influence of ionic strength on distribution was analyzed. It is shown that interaction with other coats or smooth surfaces changes the fixed charge distribution. The special effect of a possible membrane charge was calculated in addition. In this case there is a fixed, charge-free space near the membrane, depending on coat thickness, ionic strength and membrane charge/surface coat charge ratio. For several cases energies, electric potentials and fixed charge distributions are given. The general result is that fixed charge distribution is always composed of a constant space charge density over a part of or the whole surface coat and, with some exceptions, of a surface charge density at the border of the surface coat. Conclusions for electrophoretic mobility measurement interpretations are drawn.

Cell Membrane↗
PubMed1983

Quantitative measurements of contact interactions between solid surfaces--a novel method for characterizing surface properties of biomaterials.

A method developed in colloid chemistry for quantitative measurements of adhesion forces in dispersive systems was adapted for the characterization of surface properties of biomaterials in electrolyte solutions and in the presence of macromolecular adsorption layers. The adhesion force between a reference surface (glass) and different polymers (polyurethanes and cellulose derivatives) was found to be dependent on the immersion time of polymers in electrolyte and on the formation of adsorption layers of serum albumin and fibrinogen. It was concluded that the adhesion forces measured can be considered as a further complex interfacial parameter reflecting such microscopic surface properties of biomaterials, which are responsible for biocompatibility.

Adhesiveness↗
PubMed1983

Electrokinetic properties of polymer and glass surfaces in aqueous solutions: experimental evidence for swollen surface layers.

Streaming potential and streaming current measuring techniques have been applied to polymer and glass surfaces to study solid/liquid interface electrical properties. The streaming current technique provides a reliable electrokinetic potential value, preexcluding surface conduction. A combination of both techniques results in experimental evidences for swollen, gel-like layers at (even apolar) polymer surfaces. Protons and hydroxide ions are the potential-determining ions indicated by the dependence of streaming potential on pH. Human serum albumin adsorption at a glass surface is discussed in terms of spatial distribution of the fixed macromolecular electric charges.

Adsorption↗