Precipitin and mitogenic behavior of dimeric and tetrameric concanavalin A

The results of double diffusion and quantitative precipitin tests show that in contrast to the concanavalin A tetramer, the dimer is incapable of precipitating glycogen. The results support previous work suggesting that dimers composed of two fragmented monomer units possess only one binding site for carbohydrate (McKenzie and Sawyer, J. Biol. Chem. 1973. 248: 549). On the other hand, dimer and tetramer species had similar mitogenic activity as measured by the incorporation of radioactive thymidine by mouse spleen lymphocytes and induced cap formation to similar degrees. Results are discussed in terms of the affinity and valency of the polymeric forms and their stability at the cell surface.     

Effects of cadmium on the growth and uptake of cadmium by microorganisms

Six species of microorganisms, Escherichia coli, Bacillus cereus, Lactobacillus acidophilus, Staphylococcus aureus, Streptococcus faecalis and Actinomyces niger, were grown under suitable conditions in appropriate media. Cadmium chloride was added to provide 0, 5, 10, 20, 40, and 80 mug of Cd per ml. At 40 and 80 mug of Cd per ml, E. coli and B. cereus grew well and the other species were repressed. Cd uptake patterns differed significantly among the species tested. The significance of these data with respect to Cd in food chains is discussed.     

Comprehensive viral immunology of multiple sclerosis. I. Clinical, epidemiological, and CSF studies

Epidemiological, clinical, and CSF data were collected on 87 patients with clinically definite multiple sclerosis (MS) and 50 with probable MS. As part of a study of immunologic reactivity to viral antigens, a control group separated into 26 patients with probable inflammatory neural disease and 140 with noninflammatory neural disease was similarly studied. Among the groups with MS, females predominated and both Oriental and Spanish surnamed patients were under-represented. The spinal cord, optic nerves, and brainstem were the most common sites of initial disease and more than 20% of the patients had only cord symptoms after several years of disease activity. Of several CSF assays used, determination of oligoclonal IgG bands by agarose electrophoresis was most useful diagnostically.     

Chromatographic purification of soluble elastin

An improved method for extraction and purification of soluble elastin from aortas of copper-deficient swine has been devised. It depends upon the use of both acidic and neutral protease inhibitors during preparation. Collagen is first precipitated with acetic acid. A two-step separation and purification of elastin from the collagen-free extract is based on absorption of the acidic proteins on DEAE-cellulose and gel filtration through agarose. The protein recovered is homogeneous by gel electrophoresis. It has the molecular weight (75,000) and amino acid composition of the soluble elastin from the same source prepared by repeated coacervation.     

Epistemic Uncertainty Workshop

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