Platelet adhesion, contact phase coagulation activation, and C5a generation of polyethylene glycol acid-grafted high flux cellulosic membrane with varieties of grafting amounts.

Grafting of polyethylene glycol chains onto cellulosic membrane can be expected to reduce the interaction between blood (plasma protein and cells) and the membrane surface. Alkylether carboxylic acid (PEG acid) grafted high flux cellulosic membranes for hemodialysis, in which the polyethylene glycol chain bears an alkyl group at one side and a carboxyl group at the other side, have been developed and evaluated. PEG acid-grafted high flux cellulosic membranes with various grafting amounts have been compared with respect to platelet adhesion, the contact phase of blood coagulation, and complement activation in vitro. A new method of quantitating platelet adhesion on hollow-fiber membrane surfaces has been developed, which is based on the determination of lactate dehydrogenase (LDH) activity after lysis of the adhered platelets. PEG acid-grafted high flux cellulosic membranes showed reduced platelet adhesion and complement activation effects in grafting amounts of 200 ppm or higher without detecting adverse effects up to grafting amounts of 850 ppm. The platelet adhesion of a PEG acid-grafted cellulosic membrane depends on both the flux and grafting amounts of the membrane. It is concluded that the grafting of PEG acid onto a cellulosic membrane improves its biocompatibility as evaluated in terms of platelet adhesion, complement activation, and thrombogenicity.

Automated imaging and quantitation of tumor cells and CFU-GM colonies in microcapillary cultures: toward therapeutic index-based drug screening.

Human colony forming units (CFUs) from both malignant and hematopoietic tissues can be assayed in vitro in microcapillary cultures, an alternative cloning system to the Petri dish methodology. For technical reasons, microcapillary culture may be ideally suited for new drug screening by therapeutic index. To achieve the high output required by screening programs, automated quantitation of CFUs is required. Toward this end, this paper reports the development of a prototype CapScan, an image analysis system that uses a novel axial laser illumination system to detect tumor cell colonies and, with technical modifications, CFU-granulocyte-macrophage (CFU-GM) colonies in microcapillary cultures. As currently configured, the CapScan can quantify colonies grown in a rack of 18 microcapillary cultures in 30 minutes or less. The sensitivity and detection specificity of tumor cell colonies is >90% with a coefficient of variance of 5-40%, dependent upon colony number. Over a range of colony numbers, CapScan and manual colony counts showed a linear correlation > -0.9, and yielded identical results in assays of doxorubicin inhibition of clonogenic P388 cells. As an additional advantage, the growth kinetics of individual colonies can also be monitored with the CapScan, making distinctions between cytotoxic and cytostatic drugs possible; colonies of freshly isolated human tumor cells can also be quantified. Thus, a microcapillary-based human tumor cloning assay that tests for resistance and/or sensitivity to chemotherapeutic agents may be useful in drug development programs and may also facilitate the development of chemotherapy for individual patient tumors, especially when tumor availability is limited.

A new method of determining the solute permeability of hollow-fiber dialysis membranes by means of laser lights traveling along optic fibers.

To develop a new method of determining solute permeability more simply and accurately, the authors employed light from a laser traveling along quartz optic fibers. Dialysis experiments at 310 K were made with a single hollow fiber containing aqueous test solutes. A membrane tube was sealed at either end with quartz optic fibers. Helium-neon and helium-cadmium laser lights emitted from one of these optic fibers into the test solution at wavelengths of 543 and 442 nm for vitamin B12 and cytochrome-C, respectively, were caught by the other optic fiber and detected with a silicon photodiode. The solute permeability for cytochrome-C obtained by this method was almost in agreement with that for beta-2-microglobulin by the radioisotope method. This study demonstrates the usefulness of light from a laser traveling along quartz optic fibers in determining the solute permeability of hollow-fiber dialysis membranes.