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Biomedical subjects

L Shannon

Publications and source records attributed to L Shannon.

5 recordsLinked to original sources
PubMed1978

Spatial strategies in the counting of young children.

3--6-year-old children counted 7, 10, and 14 items arranged in columns or in rows. Developmental changes in spatial strategy and the relation of strategy to accuracy were examined. Increases with age in the organization of children's counting sequences were observed as they progressed from (a) a counting sequence based on the proximity of an item to the one previously counted, to (b) a sequence based on the exterior form of the array, to (c) a sequence based on the linear arrangement of items. The column or row arrangement of items did not affect strategy choice, but increasing the number of items caused some children to revert to a less organized count. Fewer errors were associated with more mature strategies at all ages.

Achievement↗
PubMed1976

A barley lectin that binds free amino sugars. I. Purification and characterization.

A lectin was isolated from barley seen which bound the coat glycoprotein of barley stripe mosaic virus (Type strain) and precipitated the virus from solution. Purification of the barley lectin was achieved by fractionation with ammonium sulfate and successive column chromatography on DEAE cellulose and cellulose phosphate. The barley lectin was homogeneous as ascertained by polyacrylamide gel electrophoresis, isoelectric focusing, and from immunochemical tests. No isolectins were detected. The lectin has a molecular weight of 31 000 daltons and is not a glycoprotein. Each virion can accomodate between 200 to 300 molecules of lectin. Barley lectin was shown to be specific for D-glucosamine, D-galactosamine and D-mannosamine with little distinction among the epimeric configurations at carbons 2 and 4. Free amino groups of D-glucosamine and D-galactosamine were detected on the coat glycoprotein of Type strain barley stripe mosaic virus and these sugars appear to serve as receptors for the barley lectin.

Agglutination Tests↗
PubMed1976

Carbohydrate composition of central nervous system synapses. Analysis of isolated synaptic junctional complexes and postsynaptic densities.

The composition of specialized structures present at synapses within the central nervous system was elucidated by biochemical analysis of fractions enriched in synaptic junctional complexes and postsynaptic densities. The results indicate that the synaptic junctional complex is primarily protein together with some glycoproteins. The synaptic junctional complex proteins are similar in amino acid composition to synaptic membrane proteins; they are not expecially rich in basic residues, as previously suggested. The major carbohydrates present in the synaptic junctional complex and postsynaptic density glycoproteins are mannose, galactose, and glucosamine, with lesser amounts of fucose, N-acetylneuraminic acid, and galactosamine. Comparison with the synaptic membrane fraction indicates that galactose is more concentrated in the synaptic junctional complex and mannose in the postsynaptic density. Glucose is dramatically enriched in both these fractions. Sucrose binding during isolation may partially account for the glucose enrichment.

Amino Acids↗