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Biomedical subjects

C E HALL

Publications and source records attributed to C E HALL.

At least 55 records · Page 3Linked to original sources
PubMed1959

The fibrinogen molecule: its size, shape, and mode of polymerization.

Improved electron micrographs of the shadow-cast bovine fibrinogen molecule have been obtained establishing its general morphology and dimensions in the dry state. It consists of a linear array of 3 nodules held together by a very thin thread which is estimated to have a diameter of from 8 to 15 A, though it is not clearly resolved. The two end nodules are alike but the center one is slightly smaller. Measurements of shadow lengths indicate that nodule diameters are in the range 50 to 70 A. The length of the dried molecule is 475 +/- 25 A. Adopting the molecular volume from previous physical chemical data and the general morphological features and length from electron microscopy, we calculate the diameters of the end nodules to be 65 A and the center one as 50 A. The model of the molecule so obtained is consistent with the electron microscopical observations and the data from physical chemistry. The intermediate polymers formed when fibrinogen is activated with thrombin were also examined and found to be end-to-end aggregates of altered fibrinogen molecules which shrink in length during the process. Intermediate polymer lengths are from 1000 to 5000 A. The nodular nature of fibrinogen, its shrinkage and end-to-end aggregation on polymerization permits us to deduce an explanation for the system of cross-bands previously observed in stained fibrin fibrils.

Animals↗
PubMed1958

Morphological features of DNA macromolecules as seen with the electron microscope.

Desoxyribosenucleic acid molecules isolated from salmon sperm were studied with the electron microscope. The essential step in the technique which makes it possible to visualize the individual molecules consists in a preparative step wherein the materials are supported on the extremely smooth surface of cleaved mica where they are shadow-cast with platinum, which is then backed with a supporting film and stripped for observation in the usual manner. The DNA, which was originally about 8 million molecular weight, was also examined after fragmentation by sonic vibration. The fragments show a certain degree of rigidity and the ends generally terminate abruptly, indicating that the double helices of the Watson-Crick model both break close to the same place. DNA molecules heated to temperatures between 90 and 100 degrees C, coil up into amorphous patches, although a few apparently unaltered molecules survive such heating.

Aluminum Silicates↗