Effects of substrata and method of tissue dissociation on adhesion, cytoskeleton, and growth of chick retinal pigmented epithelium in vitro.

In this report we compare attachment, morphology, and growth of retinal pigmented epithelial (RPE) cells isolated by either EDTA or dispase digestion and plated onto either uncoated substrata (plastic or glass) or substrata derivatized by covalent conjugation of proteins of reconstituted basement membrane gel. We show that the derivatized substrata promote better initial attachment and subsequent cell growth than the uncoated substrata. These effects are independent of the method of dissociation of cells from the tissue. Cell morphology, however, is strongly affected by the method used for tissue dispersion. The dispase-dissociated cells are very flat, display a circumferential arrangement of microfilaments and elaborate extensive arrays of vinculin-containing cell-to-cell junctions. In contrast, EDTA-dissociated cells are much less spread, display straight microfilament bundles criss-crossing the cytoplasm and have less extensive cell-to-cell junctions. The protein-derivatized substrata also promote maintenance of differentiated traits, such as pigmentation, by the RPE cells.

Bioimplant surfaces: binding of fibronectin and fibroblast adhesion.

The adhesion of baby hamster kidney 21C/13 fibroblasts to surfaces of passivated titanium, carbon fibers, bioactive glasses B5 and B6, fibronectin-precoated passivated titanium, and fibronectin-precoated B6 was quantified. The order of adhesive cell avidity for the uncoated surfaces was passivated titanium (greatest), B6 and carbon fibers (intermediate), and B5 (least). Precoating with fibronectin enhanced the adhesive characteristics of fibroblasts on passivated titanium and B6 by 74% and 118%, respectively.

Pulmonary macrophages are attracted to inhaled particles through complement activation.

Pulmonary macrophages play a central role in clearing inhaled particles from the lung. Previously, we showed that inhaled asbestos fibers activate complement-dependent chemotactic factors on alveolar surfaces to facilitate macrophage recruitment to sites of fiber deposition. In the studies presented here, we have tested a variety of inorganic particles for complement activation in vitro and correlated these data with results on particle-induced macrophage accumulation in vivo. We found that significant chemotactic activity was activated in rat serum and concentrated lavaged proteins by chrysotile and crocidolite asbestos, iron-coated chrysotile asbestos, fiberglass, and wollastonite fibers, as well as by carbonyl iron and zymosan particles. Ash from the Mt. St. Helens volcano did not induce chemotactic activity in either the serum or lavaged proteins. Rats were exposed to brief aerosols of each of the particles listed above (except zymosan). All the particle types studied were deposited primarily at first alveolar duct bifurcations. In addition, all of the particles, except Mt. St. Helens ash, induced at 48 h postexposure significant accumulations of macrophages at these sites. Time-course studies of carbonyl iron particle exposure demonstrated that iron induced a rapid macrophage response, but both particles and phagocytic macrophages were cleared from alveolar surfaces within 8 days after exposure. The Mt. St. Helens ash induced no macrophage accumulation at any time postexposure. We conclude that particles with a wide variety of physical characteristics are capable of activating complement and consequently attracting macrophages, both in vitro and in vivo. We suggest that complement activation is a mechanism through which pulmonary macrophages can detect inhaled particles on alveolar surfaces.

Plastic ESR tubes: does static electricity affect the results?

Static electrical charges were applied to the inside and outside surfaces of plastic ESR tubes, and this had no demonstrable effect on the results of the test. A further study confirmed that the plastic apparatus gave identical results to the standard Westergren method using glass tubes.

Nitrocellulose and polyvinyl coatings prevent sperm adhesion to glass without affecting the motility of intact and demembranated human spermatozoa.

The effectiveness of several glass coating agents in preventing sperm adherence to glass surfaces for both intact and demembranated human spermatozoa was investigated. These agents included bovine serum albumin (BSA), Sigmacote, poly glu-lys, Collodion and Formvar. The presence of at least 5% of seminal plasma in sperm suspensions prevented sperm adhesion to glass surfaces. On the other hand, 56% of washed spermatozoa resuspended in an isoosmotic buffer containing 1 mg/ml of BSA attached to glass. Collodion, Formvar and Sigmacote reduced sperm attachment to glass to 2, 5 and 7%, respectively. BSA was partially effective, with 20% sperm adherence to glass, and poly glu-lys was totally ineffective. Whereas Sigmacote and BSA coatings lacked transparency, Collodion always achieved the best light transmission. Demembranated reactivated spermatozoa were all attached to glass within 90 seconds of contact. This adhesion was prevented by Collodion and Formvar. Other agents were less effective or interfered with motility. In contrast to intact spermatozoa, demembranated spermatozoa have a very low progressiveness ratio (vector speed/track speed), a wide beating amplitude and because of their whiplash flagellar movement, their motility resembles that of hamster capacitated spermatozoa.

Determination of binding strength and kinetics of binding initiation. A model study made on the adhesive properties of P388D1 macrophage-like cells.

The adhesive properties of the mouse P388D1 macrophage-like line were explored. Cells were deposited in glass capillary tubes, and the kinetics of adhesion and spreading were studied. Binding involved the cell metabolism since it was decreased by cold, azide, or a divalent cation chelator. Glass-adherent cells were subjected to calibrated laminar shear flows with a highly viscous dextran solution. A tangential force of about 5 X 10(-3) dyn/cell was required to achieve substantial detachment. The duration of application of the shearing force strongly influenced cell-substrate separation when this was varied from 1-10 s. Further, this treatment resulted in marked cell deformation, with the appearance of an elongated shape. Hence, cell-substrate separation is a progressive process, and binding strength is expected to be influenced by cell deformability. The minimum time required for adhesion was also investigated by making cells adhere under flow conditions. The maximum flow rate compatible with adhesion was about 1000-fold lower than that required to detach glass-bound cells. A simple model was devised to provide a quantitative interpretation for the experimental results of kinetic studies. It is concluded that cell-to-glass adhesion required a cell-substrate contact longer than a few seconds. This first step of adhesion was rapidly followed by a large (about 1000-fold) increase of adhesion strength. It is therefore emphasized that adhesion is heavily dependent on the duration of cell-to-cell encounter, as well as the force used to remove so-called unbound cells.

Type-I collagen production by human odontoblast-like cells in explants cultured on cyanoacrylate films. Electron-immunolocalization of fibronectin at cell/film interface.

Odontoblast-like cells derived from human tooth pulps were maintained in explant culture and grown either on glass coverslips only (used as control) or on glass coverslips coated with cyanoacrylate films. Ultrastructural and cyto-morphometric evidence showed that cells exposed to cyanoacrylate, in contrast to controls, display a significant decrease of rough endoplasmic reticulum and mitochondria. In addition, immunofluorescent staining and radioimmunoassays for type-I collagen suggested disturbances in production for the exposed cells. The use of anti-fibronectin antibodies with electron-microscopic immunoperoxidase-labelling demonstrated that the adherence of cells to cyanoacrylate can involve both adhesion plaques and fibronectin. These results therefore suggest that there were no apparent differences in the adhesion interaction of cells between glass and cyanoacrylate substrates.

[Effect of beta-adrenoreceptor blockade on cell division processes in the corneal and tongue epithelium of white rats with chronic oxygen starvation]. / Vliianie blokady beta-adrenoretseptorov na protsessy kletochnogo deleniia épiteliia rogovitsy i iazyka belykh krys pri khronicheskom kislorodnom golodanii.

A study was made of the changes in the mitotic activity, DNA synthesis, and the number of pathological mitoses after administration of the beta-adrenoblocker propranolol in the corneal and tongue epithelium of white rats kept in pressure chamber for 7 days (4 h daily) at a "height" of 9000 meters. The mitotic and the label indices (inclusion of 3H-thymidine by the epithelium nuclei) were analysed for mitotic activity and DNA synthesis, respectively. The experiments showed that the mitotic activity, DNA synthesis, the number of pathological mitoses were stabilized due to the propranolol administration.

Patterns of adsorption of proteins from human plasma onto foreign surfaces.

The deposition of proteins on blood-contacting surfaces is known to be a determining factor in subsequent thromboembolic events. The composition of the protein layers and how they change with time are unknown. To generate information relevant to these questions, the quantities of albumin, fibrinogen and IgG adsorbed on seven surfaces from human plasma as a function of time were measured using a tracelabeling method. Materials studied include several segmented polyether-urethanes, glass, siliconized glass (SG), polystyrene (PS) and polyethylene (PE). Fibrinogen, surprisingly, was not adsorbed from plasma to any of the hydrophilic surfaces. On PE and SG adsorption passed through an early maximum (before 2 min) then declined to near zero. Only on PS was adsorption substantial and constant with time. Albumin was also not detected on the hydrophilic surfaces. IgG but was adsorbed substantially on the hydrophobic surfaces. IgG was detected on all surfaces, although in relatively low surface concentrations. These results suggest: 1. that the plasma itself interacts with initially adsorbed proteins, 2. that the role of fibrinogen adsorption in foreign-surface initiated thrombosis may need to be reevaluated and 3. that since the major plasma proteins are only minimally adsorbed, trace proteins may be important in blood-material interactions.