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W E Fowler

Publications and source records attributed to W E Fowler.

26 records · Page 2Linked to original sources
PubMed1982

Polymorphism of actin paracrystals induced by polylysine.

We describe a method for the induction of different polymorphic forms of actin filament paracrystals. This polymorphism is probably based on differences in the stagger and/or polarity of adjacent filaments in single-layered paracrystals and by superposition of different layers in multilayered paracrystals. The helical parameters defining the filament geometry are indistinguishable for the different polymorphic forms observed and for the four different actins used. Analysis of these paracrystals, some of which are ordered to better than 2.5 nm, should provide a reference structure suitable for alignment and orientation within the actin filament of high resolution models of the actin monomer obtained from crystal data.

Actins↗
PubMed1981

Structure of the fibrin protofibril.

We identified the two-stranded fibrin protofibril and studied its structure in electron micrographs of negatively stained specimens. Based on these images and on considerations of symmetry, we constructed a model of the protofibril in which the two strands of trinodular fibrin molecules are related by a two-fold screw axis between the strands and two-fold axes perpendicular to them. The two strands are held together by staggered lateral contacts between the central nodules of one strand and outer nodules of the other. The molecules within a strand are joined by longitudinal contacts between outer nodules. This interpretation of the structure of protofibrils is supported by images of trimer complexes whose preparation and structure are described here, in which the central nodule of a fibrin monomer is attached to the crosslinked outer nodules of two other molecules. We conclude that the association of protofibrils to form thicker fibers must involve a second type of lateral contact, probably between outer nodules of adjacent, in-register strands. In total, we identify three intermolecular contacts involved in the polymerization of fibrin.

Fibrin↗
PubMed1981

Crystalline actin sheets: their structure and polymorphism.

Crystalline sheets of Acanthamoeba actin induced by the trivalent lanthanide gadolinium exist in three different polymorphic forms, which show different striation patterns and surface topographies. We have called these different forms "rectangular" and "square" sheets, and "cylinders" and have shown that each of the three forms is constructed from common "basic" lattices associated in different ways. We have used image processing of electron micrographs to obtain a model for the actin molecule in projection to a resolution of 1.5 nm. The overall dimensions observed in these images are 5.6 x 3.3 x 4.5 nm, and the molecule itself appears distinctly bilobed with the two lobes separated by a cleft. actin monomers in the sheets are arranged with P2 symmetry and are therefore packed in a manner different from that of the molecules in actin filaments. Because approximately 35% of the surface area of the actin molecule is exposed on the surface of these sheets, the sheets should be useful to study the stoichiometric binding of actin-binding proteins to the actin molecule.

Actins↗
PubMed1980

Electron microsocpy of plasmic fragments of human fibrinogen as related to trinodular structure of the intact molecule.

We have examined rotary shadowed, purified plasmic fragments of human fibrinogen with the electron microscope and have determined the relation of these fragments to the intact fibrinogen molecule. Both intact fibrinogen and its earliest cleavage product, fragment X, are trinodular. The next largest product, fragment Y, consists of two linked nodules. The two terminal products, fragments D and E, are single nodules. From measurements of simultaneously shadowed specimens of these different species, we conclude that the outer nodules of the trinodular fibrinogen molecule are the fragment D-containing regions and the central nodule is the fragment E-containing region.

Electrophoresis, Polyacrylamide Gel↗
PubMedDate not supplied

Movement disorders after status epilepticus and other brain injuries.

A retrospective medical record review was conducted of 173 consecutive children hospitalized for acquired brain injuries on a specialized pediatric rehabilitation service. The chart review identified children who developed movement disorders with acquired brain injuries: 8 with status epilepticus, 2 with trauma, and 1 with anoxia. Movement disorders were observed more frequently following status epilepticus (8 of 12) than following other causes of acquired brain injury (3 of 161; P = .0001). Four additional children had severe neurologic deficits following status epilepticus but did not develop movement disorders. The 11 patients who developed movement disorders had choreiform movements predominantly. Even though status epilepticus is a clinical phenomenon resulting from a variety of etiologies, the features of movement disorders in these children were strikingly similar. The pathophysiology of this complication is unknown.

Anticonvulsants↗