Consensus of a group of professional societies and diagnostic companies on guidelines for interim reference ranges for 14 proteins in serum based on the standardization against the IFCC/BCR/CAP Reference Material (CRM 470). International Federation of Clinical Chemistry. Community Bureau of Reference of the Commission of the European Communities. College of American Pathologists.

The release in 1993 of a new reference material for serum proteins, CRM 470/RPPHS 5 has given rise to a great improvement in the between-laboratory variability of serum protein measurements worldwide. Conversion to the new reference material results in significant changes in reference values for some proteins. The establishment of new reference ranges will take a considerable time, and in the interim several professional societies and diagnostic companies have agreed to use consensus reference ranges based on studies already undertaken.

Recommendations for the selection and use of protocols for assignment of values to reference materials.

It is essential that testing of patient samples give values that are traceable to those in a recognized, authorizative reference material. In addition, samples used for laboratory proficiency testing must have values assigned from such a reference material if results are to be comparable among materials and laboratories. As a result, the assignment of values to secondary and tertiary reference materials, calibrants, controls, and proficiency samples should be performed as precisely as possible, within reasonable limits. The intent of this document is to give guidelines for assignment of values at three levels of transfer. 1) from primary to secondary reference, materials, such as international or national references; 2) from secondary to tertiary reference materials, such as manufacturers' in-house calibrants and controls; and 3) from tertiary reference materials, such as manufacturers' in-house calibrants and controls; and 3) from tertiary reference materials to working calibrants and controls. It is hoped that these guidelines will facilitate the selection and utilization of an appropriate value transfer protocol for each level of value assignment. Because of the wide variety and nature of analytes, however, the guidelines are intentionally broad and may require revision for specific analytes.

Characterization and quantification of plasma proteins excreted in faeces from healthy humans.

Faecal plasma protein loss was studied in 38 healthy adults. Using crossed immunoelectrophoresis and single radial immunodiffusion the most frequently found proteins were alpha 1-antitrypsin, IgA, alpha 1-antichymotrypsin (found in 97, 92, and 84% of subjects), prealbumin and IgM (both found in 55%). The major plasma proteins, albumin and IgG, were found in 37 and 13% of subjects, respectively, and in trace amounts only. alpha 2-macroglobulin could not be detected. There was no relation between the presence of proteins in faeces and their plasma concentration. When added to faeces, alpha 1-antitrypsin, alpha 1-antichymotrypsin, and prealbumin were resistant to incubation (37 degrees C, 48 h), whereas albumin, IgG, IgM, and IgA were rapidly degraded (within 8-24 h). Some IgA was bound to secretory component, indicating enteric secretion. alpha 2-macroglobulin was semi-resistant to degradation, but its passage to the intestinal lumen may have been prevented by its molecular size. In conclusion, resistance to degradation, enteric secretion, and low molecular weight are the primary factors which favour the excretion of plasma proteins in faeces. The technique used in this study allows further studies in patients with inflammatory changes and protein-losing enteropathy.

New international reference preparation for proteins in human serum (RPPHS).

Quality-control surveys in recent years, in various parts of the world, have shown poor between-laboratory agreement for measurements of plasma proteins. Despite the existence of international reference materials distributed by the World Health Organization, standards produced by diagnostics manufacturers and professional organizations differ significantly in their ascribed values. The reasons for this are complex but include poor availability of the primary materials, confusion about their use, and the fact that their turbidity on reconstitution precludes their use in modern optical immunoassays. This unfortunate situation led to an important initiative to produce sufficient quantities of a widely available, optically clear secondary reference material for plasma proteins that could be used worldwide by manufacturers, professional organizations, and laboratories. Here we present an overview on how the laboratory community, including manufacturers, clinical laboratories, professional societies, and regulators, has reached what we consider is a successful conclusion to a difficult problem.

Separation of macromolecules in isotachophoresis systems involving single or multiple counterions.

The isotachophoresis principle provides unique opportunities for rational designs of fractionation procedures involving molecules. Theoretically any two charged molecules that are soluble under the experimental conditions involved can be physically separated if their electrophoretic net mobilities differ only slightly in the electrophoresis medium used. A theoretical and practical outline is presented that enables the reader to set up this fractionation system and on a rational basis develop fractionationprocedures for a given set of charged macromolecules by isotachophoresis with simple and well characterized ampholytes as spacer substances. The planning of preparative experiments in this approach is based on results obtained from rapid analytical screens on a microgram scale. The report includes an appendix containing the theoretical basis for computation of buffer compositions in the isotachophoretic steady state with mono/polyvalent constituents in systems involving one or more counterions and controlled amounts of interfering ions.