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At least 451 records · Page 25Linked to original sources
PubMed1997

Amphiphilic networks. X. Diffusion of glucose and insulin (and nondiffusion of albumin) through amphiphilic membranes.

Select semipermeable amphiphilic membranes have been prepared and their diffusional characteristics for glucose, insulin, and albumin investigated. The membranes were prepared by cast copolymerization of a hydrophilic monomer (i.e., N,N-dimethyl acrylamide, or N,N-dimethylaminoethyl methacrylate) with the hydrophobic crosslinker methacrylate-ditelechelic polyisobutylene. The products have sufficient mechanical properties for the fabrication of swollen membranes, sheets, tubes, etc. Membranes have been identified which allowed the rapid simultaneous countercurrent diffusion of glucose (Mn = 180 Da) and insulin (Mn = 5733 Da) but did not allow albumin (Mn approximately 60,000 Da) to pass. Evidently, the effective molecular weight cutoff point of these membranes is in the 6-60-KDa range.

Albumins↗
PubMed1996

Identification and characterization of various differentiative growth plate chondrocytes from porcine by countercurrent centrifugal elutriation.

Countercurrent centrifugal elutriation was used to separate growth plate chondrocytes from porcine basing on their differences in sizes and densities. Eighteen fractions of cells with different sizes and densities were obtained. The mean cellular volumes increased progressively in each of successive fractions, and that increase was associated with specific phenotypic changes, such as biochemical differences in DNA synthesis, proteoglycan synthesis, and activities of alkaline phosphatase. Three distinct chondrocyte subpopulations with their unique characteristics were identified among the elutriated fractions. The resting chondrocytes were found to be small in size and quiescent. The hypertrophic chondrocytes were found to be large in size and metabolically active both in alkaline phosphatase and in proteoglycan productions. The proliferative chondrocytes exhibited a high DNA synthesis rate, and their sizes were found to be between those of the resting and hypertrophic chondrocytes.

Alkaline Phosphatase↗
PubMedDate not supplied

Dye-affinity techniques for bioprocessing: recent developments.

Textile or triazine dyes play an important role as affinity ligands in protein purification. Each step of the protein purification protocol can be divided into three stages, partitioning between two phases, separation of these phases and recovery of the target protein from the enriched phase. Now developments in dye-affinity techniques are discussed emphasizing the innovations in all three stages of the protein purification process. Dye-affinity chromatography has become a routine step in protein purification. New dyes have been developed and used successfully in both traditional chromatographic mode and new modes like affinity precipitation, polymer aqueous two-phase partitioning or expanded bed chromatography. The specificity of dye techniques has been increased by both purposeful designing of new dyes and decreasing non-specific protein-dye interactions with polymer shielding. One can envisage further development and ramification of dye-affinity techniques in protein purification.

Affinity Labels↗
PubMed1993

Counterflow in isotachophoresis: computer simulation and experimental studies.

A computer model has been developed to predict the effects of co- and counter-current flows on electrophoretic transport. Model predictions are compared with experimental data obtained with the large-scale recycling isotachophoresis apparatus, recently developed in our laboratory. There were no significant changes in the steady state properties or the transient development of the Kohlrausch-adjusted profiles with and without flow. The application of counterflow in free flow isotachophoresis in early stages, before a steady state is achieved, can result in selective wash-out of slower sample components. Thus, the magnitude of counterflow can be used as a variable in optimizing separations. The characteristic features of the model render it also suitable for the simulation of electroosmotic flow in capillary electrophoresis in open tubes, where plug-type flow prevails.

Anions↗
PubMed1987

Implementation of a semiclosed large scale counterflow centrifugal elutriation system.

A semiclosed counterflow centrifugal elutriation system that minimizes the risks of contamination and cell loss is presented. A detailed description of the configuration of the system and its sterilization and assembly is provided along with examples of its application to large-scale separation of leukapheresis buffy coat and cadaveric bone marrow. We are currently using this system to deplete lymphocytes from human bone marrow prior to use in allogeneic bone marrow transplantation. The implementation of a semiclosed system increases the safety, ease of operation, and reproducibility of a technique that has the potential for a wide range of clinical applications.

Cell Separation↗