SummaryPlatelet/endothelial cell adhesion molecule 1 (PECAM-1; CD31) is crucial to the process of leukocyte transmigration through intercellular junctions of vascular endothelial cells. A monoclonal antibody to PECAM, or recombinant soluble PECAM, blocks transendothelial migration of monocytes by 70-90%. Pretreating either the monocytes or the endothelial junctions with antibody blocks transmigration. If the endothelium is first activated by cytokines, anti-PECAM antibody or soluble recombinant PECAM again block transmigration of both monocytes and neutrophils. Anti-PECAM does not block chemotaxis of either cell type. Light and electron microscopy reveal that leukocytes blocked in transmigration remain tightly bound to the apical surface of the endothelial cell, precisely over the intercellular junction. Thus, the process of leukocyte emigration can be dissected into three successive stages: rolling, mediated by the selectin dass of adhesion molecules; tight adhesion, mediated by the leukocyte integrins and their endothelial cell counter-receptors; and now transmigration, which, based on these studies, requires PECAM-1.

In this work, the suitability of imidazolium-based ionic liquid solvents is investigated for the dissolution and regeneration of silkworm (Bombyx mori) silk. Within an ionic liquid the anion plays a larger role in dictating the ultimate solubility of the silk. The dissolution of the silk in the ionic liquid is confirmed using wide-angle X-ray scattering. The dissolved silk is also processed into 100 mum-thick, two-dimensional films, and the structure of these films is examined. The rinse solvent, acetonitrile or methanol, has a profound impact on both the topography of the films and the secondary structure of the silk protein. The image depicts a silkworm cocoon dissolved in 1-butyl-3-methylimidazolium chloride and then regenerated as a film with birefringence.

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These data suggest that a combination of L. sericata ES proteinases involving chymotrypsin-like and trypsin-like activities could potentially influence wound healing events when maggots are introduced into necrotic and infected wounds, with the chymotrypsin-like activity involved in the remodelling of ECM components.

The cross-striated connecting-piece in the neck region of the mammalian spermatozoon develops from material that seems to arise between the triplets in the wall of both proximal and distal centrioles. The precursor material extends radially from the centrioles and polymerizes around them to form the connecting piece. This is not composed of "segments" or "lamellae" as usually described but is a cross-striated fibrous protein with a major period of 665 A and a complex pattern of intraperiod bands. It is considered to be homologous with the striated rootlets of cilia.During differentiation of this region, the proximal centriole develops at one end, a cylindrical prolongation which is similar in its structure but not identical with the centriole proper. This centriolar adjunct is a transient structure. The proximal centriole persists in the mature spermatozoon, but the distal centriole disintegrates during formation of the connecting-piece.The outer dense fibers of the flagellum and the cross-striated columns of the connecting piece are distinct components which arise separately and secondarily become continuous. The dense fibers originate as ridge-like radial outgrowths from the wall of the corresponding doublets in the axonemal complex. As they enlarge they separate from the doublets throughout most of their length but they remain continuous with them at their distal ends,The term "neck" was applied by classical cytologists to a poorly-defined region between the sperm head and the beginning of the middle piece, but few details of its structure could be resolved with the light microscope. A number of the descriptions of the ultrastructure of mammalian spermatozoa published in the past decade have included brief accounts of the structure of this region (Blom and Birch-Anderson, '60; Saacke and Almquist, '64; Nicander and Bane, '62a, '66; Fatwcett and Ito, '65; Hancock, '67). Although the interpretation of its structural components and the descriptive terms applied to them have varied, the morphological observations themselves appear to have been in substantial agreement. The neck is characterized by the presence of cross-striated longitudinal columns held together by their confluence anteriorly with each other and with an articular structure called the capitulum. The convex surface of the capitulum occupies the concavity of a shallow articulalr fossa in the posterior aspect of the nucleus. Near the middle piece the number of striated columns is nine corresponding to the nine outer flagellar fibers with which they appear to be ANAT. REC., 165: 153-184.continuous at the anterior limit of the middle-piece. Anteriorly, the number of columns is reduced by coalescence of two on either side to form two major columns. These, together with the other five minor columns, converge upon and merge with the capitulum. Beneath the articular surface of the latter is a cylindrical niche that encloses the proximal centriole which is oriented transversely, in the same plane as the flattening of the head. Its long axis is at an ...