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Simultaneous advances in detector technology and solid-phase separation systems, as well as the availability of powerful desktop computers, have made possible the development of "second-generation" solid-phase immunoassays. These retain the advantages of classical solid phase while significantly accelerating reaction kinetics. Hapten assays--such as for digoxin, thyroxin, and triiodothyronine uptake--in batches of 48 are processed in about 20 min from reagent introduction until hard-copy printout, with minimal operator involvement. The system also functions as a 48-detector gamma counter, capable of counting and reducing data for any 125I-based RIA that can be run in a 12 X 75 mm test tube. System control, data management, and computer screen displays of kinetic data are provided by an unmodified Hewlett Packard HP-87XM computer. User-friendly disc-based software facilitates the creation and storage of counting and data reduction protocols for as many as 30 RIAs from various manufacturers as well as up to 30 of our own assays.

A psychologically normal blind man, living and working in normal society, suffered from a severe cyclic sleep-wake disorder. Investigations showed that he had circadian rhythms of body temperature, alertness, performance, cortisol secretion, and urinary electrolyte excretion which were desynchronized from the 24-hour societal schedule. These rhythms all had periods which were longer than 24 hours and indistinguishable from the period of the lunar day.

AMONG neural cell lines the C-6 glioma, a cell line cloned from an N-methylnitrosourea (MNU)-induced experimental glioma in rat, has generated considerable interest as a model system for the study of neuroglia1. The clone was originally selected on the basis of a high production of the protein S-100, a protein believed to be characteristic of glial cells in vivo2. Since its introduction, the line has been further characterised with regard to a number of other biochemical features3. Among these is the recent demonstration of the glial fibrillary acidic (GFA) protein by immunofluorescent staining of C-6 cells maintained in certain in vitro conditions4. The GFA protein, isolated from multiple sclerosis plaques and areas of sub-ependymal gliosis in the central nervous system, has been shown to be a specific marker for fibrillary astrocytes, is believed to be a component of the 80–90 A diameter glial filaments5–8, and has not been reported in non-glial neural cell lines. It is, therefore, a useful biochemical marker for the differentiation of a type of mature astrocyte. In previous work with the C-6 line, GFA protein was found to be present by immunofluorescence in only an occasional C-6 cell maintained in monolayer or suspension cultures, and to be markedly increased in many C-6 cells when they were maintained for 12–14 d in an organ culture system using Gelfoam matrices4. Such a system is known to favour structural differentiation in vitro9. No increase of filaments was observed, however, in any of the in vitro systems used, suggesting that the synthesis of GFA protein could proceed without the formation of intracytoplasmic glial filaments4. We compared the quantitative levels of GFA protein in C-6 and other cell types in various culture conditions, using a “two-site” immunoradiometric assay recently developed in this laboratory10.

1. A procedure is described for the preparation of an insulin-immunoadsorbent containing 105–185mg. of insulin/g. of matrix, and with an antibody-binding capacity of 660mg./g. of insulin-immunoadsorbent. 2. Purified non-precipitating 125I-labelled antibodies were prepared by iodination of the antibodies while they were isolated on the insulin-immunoadsorbent in order to protect at least one antigen-binding site. 3. The radioactive antibody was simply and rapidly separated from other radioactive material and damaging reagents, and found to be up to 94% pure as judged by its reaction with insulin-immunoadsorbent and unfixed insulin. 4. The 125I-labelled antibody preparations had iodine contents of 0·5–64atoms/mol. of protein and specific radioactivities of 0·3–125mc/mg. of protein. 5. It is suggested that this is a simple method of producing a useful reagent.