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Biomedical subjects

G von Sengbusch

Publications and source records attributed to G von Sengbusch.

15 recordsLinked to original sources
PubMed2002

Polyetherimide: a new membrane-forming polymer for biomedical applications.

Membranes for biohybrid organs such as the biohybrid liver support system have to face 2 different environments, namely blood and tissue cells. Accordingly, the respective membrane surfaces must have optimal properties in terms of biocompatibility for blood or tissue. Flat membranes prepared by a phase inversion process from polyetherimide were modified by binding of tris-(hydroxymethyl)-aminomethane to obtain a surface with hydroxyl groups by binding of polyethylene imine to attach a hydrophilic macromolecule with amine groups useful as a spacer for later bonding of further ligands and by attachment of heparin. The binding of the different ligands was successful as monitored by different physicochemical methods. The blood response of plain polyetherimide was comparable to that of polyacrylonitrile, and it could be further improved by the binding of heparin. The tissue compatibility of polyetherimide and its different modifications was compared with commercial cell culture substrate membranes (Millicell) and found to be comparable for polyetherimide and even better after the modification with tris-(hydroxymethyl)-aminomethane. In conclusion, polyetherimide seems to be an interesting material for the production of membranes for application in biohybrid organ systems.

Complement Activation↗
PubMed1999

Investigation of plasma protein adsorption on functionalized nanoparticles for application in apheresis.

Particles with specific ligands for the adsorption of plasma proteins can be used in therapeutic or preparative apheresis. The development of these particles may benefit from an improved knowledge of the relationship between protein adsorption and the structure of ligands. Nanoparticles were functionalized with aliphatic diamines of increasing chain length; with the amino acids lysine, tryptophan, histidine, and their corresponding amines; and with tryptophan and histidine spaced with diamines of different length. Suitable protocols were developed for the washing of particles and the subsequent desorption of proteins adsorbed from human plasma. The adsorption pattern, as well as the quantification of the overall adsorption of proteins on these modified particles, was investigated with gel electrophoresis. This was followed by immunoblotting which yielded specific assessments of bound human serum albumin and fibrinogen. The comparison of protein adsorption with surface charge density and measured hydrophobicities yielded no simple correlations although in general more hydrophobic ligands bound higher quantities of protein. The detection of human serum albumin yielded similar results because it was observed for overall protein adsorption while the adsorption of fibrinogen expressed a different pattern. In this case, particular nanoparticles functionalized with aliphatic diamines bound significantly higher amounts of fibrinogen than all other ligands.

Adsorption↗
PubMed1984

Hollow-fiber dialyzers and their pyrogenicity testing by Limulus amebocyte lysate.

Aqueous extracts of cellulose hollow fibers (CHF) exhibit positive reactions in some Limulus amebocyte lysate (LAL) tests. However, in spite of LAL activity, the extracts produce no fever reaction in rabbits. A comparison of lysates from different suppliers shows pronounced activity differences when extracts of cuprammonium-derived CHF are tested. One of the lysates, which is fully reactive against standard endotoxin, shows no reaction with such extracts, nor do CHF extracts diminish its sensitivity to standard endotoxin. Investigations of the cuprammonium process have shown that endotoxins introduced by the linters are degraded and washed out. Other endotoxin introduction, particularly by the process water, has been excluded. Oxidative or acidic degradation of cellulose does not result in the formation of LAL-reactive material (LAL-RM). On the other hand, sterile cotton wool shows LAL reactivity, and cellulose acetate regains LAL reactivity when it is saponified. Thus, it appears likely that the LAL-RM found in CHF is of purely cellulosic origin and crossreacts with a number of commercially available lysates.

Animals↗
PubMed1984

Residual ethylene oxide in hollow-fiber dialyzers.

The deaeration and extraction kinetics of ethylene oxide (ETO) in hollow-fiber dialyzers were examined. The investigations showed that both deaeration and extraction can be described by two additive first-order kinetic expressions. The ETO content of membranes decreased rapidly at first, followed by a second slower decrease. Even after prolonged storage time, residual ETO was still detectable in the milligram range. These residuals cannot be eliminated by the usual rinsing of the dialyzer prior to use.

Ethylene Oxide↗
PubMed1979

Signal analysis of slit-scan contour data.

As a method for the preselection of alarms in gynecological cell samples, the Battelle Cytophotometry Research Group uses the slit-scan technique to obtain various cell parameters, such as the N/C ratio and the relative DNA content, from fluorescently stained cells, which are aligned one-dimensionally in the tape system designed at Battelle. The system developed at Battelle Institute analyzes all signals that exceed the background noise. As the first step in processing the slit-scan data, several threshold levels permit the separation of various artifacts. In subsequent steps, the nuclear peak is recognized, the nuclear boundaries are calculated, and seven cell parameters are determined. For the alarm detection at present only one parameter, DNA fluorescence, is used for these determinations. Visual assignment of these data to definite objects on the tape makes it possible to obtain frequency distributions of: (a) all recorded objects within the sample on the tape; (b) all signals that are classified as cells; and (c) all types of objects that preferentially cause alarms.

Cell Nucleus↗
PubMed1979

Preselection of alarms in a hybrid system for screening of cervical cancer.

In this report, a preselection of alarms in a system for automated screening of cervical cancer based on depositing the cell sample linearly as a "cell trace" on a tape and analyzing it at different decision levels with increasing complexity, and preliminary results on analyzing cervical material with this system are discussed. The "cell trace" is analyzed with the slit-scan technique. Six parameters are computed: 1) cellular diameter; 2) nuclear diameter; 3) nuclear fluorescence (acriflavin-Feulgen) as nuclear DNA; 4) cellular fluorescence; 5) nuclear to cytoplasm ratio (N/C ratio); and 6) nuclear density. At present, only nuclear fluorescence is used to define a decision boundary between normal and potentially atypical cells. Under this criteria the slit-scan analysis leaves 5% of the events in a sample that must be rechecked at a second decision level in normal cell samples. A further reduction is expected when several slit-scan parameters are used at the first decision step. All events declared suspicious will be investigated in more detail by a two dimensional image analyzing system where the fluorescence image is generated by a laser scanning system. Results obtained in preliminary experiments are discussed in this paper.

Computers↗