Adhesion Secretion Research Articles

Surface bio-magnetism on bacterial cells adhesion and surface proteins secretion

Extensive research works have been done on using magnetic fields on biological organism, but the results till date have been controversial [D.O. Carpenter, S. Ayrapetyan (Eds.), Biological Effects of Electric and Magnetic Fields, vol. 1, Academic Press, San Diego, 1994]. In spite of this, the study of surface magnetic effects on bacterial adhesion and cell growth has not been rigorously explored. The effects of surface magnetism, using perpendicularly polarized magnetic media, are evaluated on Bacillus licheniformis, a widely used bacterium in brewery [L. Kandra, a-Amylases of medical and industrial importance. J. Mol. Struct. (Theochem.), in press] and pharmaceutical [H. Ikram-ul et al., Production of alph amylase by Bacillus licheniformis using an economical medium. Bioresour. Technol. 87 (2003) 57–61] industries, by observing its adhesion and growth behavior. At different spin directions, we are able to observe a change on the biofilm formation, protein synthesis, and cell growth rate. Given that surface energy can easily penetrate through cells, this approach is an advantage over existing techniques that require direct physical contact to target cells. It also presents a new technique to cell adhesion and synthesis of surface proteins.

CXCR4-mediated adhesion and MMP-9 secretion in head and neck squamous cell carcinoma

The chemokine CXCL12 (SDF-1) and its receptor, CXCR4, have been implicated in organ-specific metastases of several malignancies. Head and neck squamous cell carcinoma (HNSCC) predominantly metastasizes to lymph nodes, and recent evidence has shown that CXCL12 stimulates HNSCC migration. We explored the potential role of CXCR4 in mediating other metastatic processes in HNSCC cells. CXCR4 mRNA and cell-surface expression was assessed in HNSCC cell lines. CXCR4 mRNA expression was detected in five HNSCC cell lines. Cell-surface CXCR4 was also detected in each of the HNSCC cell lines and in resected HNSCC tissues. CXCL12 induced rapid intracellular calcium mobilization in a metastatic HNSCC cell line (HN), as well as rapid phosphorylation of ERK-1/2. HNSCC cell adhesion to fibronectin and collagen was increased by CXCL12 treatment, while the addition of an inhibitor of ERK-1/2 signaling, PD98059, reduced the effects of CXCL12. CXCL12 also increased the active matrix metalloproteinase (MMP)-9 secreted. Thus, HNSCC cells express functional CXCR4 receptors that induce rapid intracellular signaling upon binding to CXCL12. Such binding leads to increased HNSCC cell adhesion and MMP secretion, suggesting that CXCR4 may be a novel regulator of HNSCC metastatic processes.

Anterior adhesive areas and adjacent secretions in the parasitic flatworms Decacotyle lymmae and D. tetrakordyle (Monogenea: Monocotylidae) from the gills of stingrays

Abstract. The monogeneans Decacotyle lymmae and D. tetrakordyle (Monocotylidae: Decacotylinae), from gills of the dasyatid stingrays Taeniura lymma and Pastinachus sephen, respectively, have a single aperture for adhesive secretion on each side of the anterior ventrolateral region. Rod‐shaped bodies (S1) and electron‐dense spherical secretion (S2) exit through specialised ducts opening adjacent to one another within these apertures. The S1 bodies are 230 ± 11 nm wide and ≥4 μm long in D. lymmae and 240 ± 9 nm wide and ≥3.3 μm long in D. tetrakordyle. The S2 bodies have a diameter of 88 ± 7 nm in D. lymmae and 65 ± 6 nm in D. tetrakordyle. The apertures are unusual in being extremely small (internal diameter, 3–5 μm). Each aperture has a slit‐like surface opening as small as 160 nm wide, surrounded by muscle fibres indicating that they may be opened and closed. The aperture is also surrounded and underlain by muscle fibres that may aid in secretion from, or even eversion of, the tissue within the aperture. Sensilla/cilia are also found within the apertures. Additional secretions from anteromedian and anterolateral glands (body glands), each containing granular secretions, occur in profusion and exit anteriorly and posteriorly to the position of the apertures, through duct openings in the general body tegument. These granular secretions do not appear to be associated with anterior adhesion. Both species show similarities in aperture, underlying tissue, sense organ, and secretion detail, in accordance with findings from other monogenean genera, and which supports the importance of such data for phylogenetic studies.

The role of adhesion in prey capture and predator defence in arthropods

Adhesive devices are used by arthropods not only in terrestrial locomotion but also in prey capture and predator defence. We argue that the physical mechanisms involved in both these contexts must mainly be capillarity and the viscosity of an adhesive secretion, whereas other mechanisms, such as friction or intermolecular forces, are of minor importance. Adhesive prey-capture devices might function as passive devices or might be actively extended toward the prey, sometimes in a very rapid manner. Adhesive mechanisms used for predator defence might involve firm adhesion to the substratum or the discharge of a sticky secretion to immobilize the appendages of the opponent. We review the occurrence of adhesive devices as employed in both functional contexts across the Arthropoda and argue that these mechanisms are of particular importance for slow-moving and relatively clumsy life forms. We discuss three case studies in more detail. (1) Loricera larvae (Carabidae) use galeae with an extremely flexible cuticle in combination with an adhesive secretion. (2) Adult Stenus species (Staphylinidae) employ two highly flexible paraglossae that are covered by an adhesive emulsion of lipid droplets dispersed in an aqueous proteinaceous liquid. (3) Springtails often adhere to the mouthparts, the antennae, the legs, or other parts of the integument of Stenus larvae before being captured with the mandibles.

Understanding osteoclast formation and function: implications for future therapies for osteoporosis

Purpose of review: The authors summarize recent strategic insights into the mechanisms that underlie osteoclast formation, function, and survival, and explore and analyze possible therapeutic implications. Bone loss can be the result of relative or absolute increases in osteoclastogenesis or osteoclast function, which accordingly offer natural targets for therapeutic maneuvers. Recent findings: The recent introduction of molecular tools for the study of stem cell differentiation, osteoclast culture, osteoclast signaling mechanisms, and transgenic animals offers insights into such opportunities, which are discussed along the following lines. First, obligatory signaling systems are required for osteoclast determination and development from hematopoietic stem cell precursors, of which the most notable involve the receptor activator for nuclear-factor κB (RANK) signaling system. Second, modulatory rather than obligatory agents, including some cytokines and estrogen, have an established or potential clinical use. Third, cell physiologic processes of polarization to form ruffled membranes, bone matrix adhesion, and acid and protease secretion into the resorptive hemivacuole offer further opportunities for drug targeting. Fourth, there are both the local feedback regulatory mechanisms that detect extracellular Ca2+ changes and the systemic regulatory mechanisms involving the hormone calcitonin. Lastly, there are recent important developments in bisphosphonate therapy that remain of primary importance for osteoporosis management in humans. Summary: The authors argue that the recent clarification of both osteoclastogenesis, the major functional specializations required for osteoclastic bone resorption, and of some of their associated, highly expressed proteins provide potential therapeutic targets that may modify bone degradation usefully in attempts to relate basic and translational issues to future antiresorptive therapies.

Structural determinants of blockade of eosinophil activation, adhesion and secretion by synthetic analogs of phomactin

We examined the structural determinants of phomactin analogs to assess their efficacy as antagonist of PAF. Six analogs of phomactin were synthesized to determine their inhibitory effects on adhesion, superoxide release, leukotriene C 4 (LTC 4) synthesis and [ 3H]PAF binding in human eosinophils. Phomactin analogs inhibited both PAF- and IL-5-induced eosinophil adhesion. Analog A, which bears an alkene moiety between C-1 and C-14, a ketone at the C-2 position, and an alkyne moiety between C-3 and C-4, had the greatest anti-adhesive effect. Change of the alkene between C-1 and C-14 to an alkane (analog I) decreased the anti-adhesive effect by 2.5–4 fold, while substitution of ketone by hydroxyl (analog G) at the C-2 position caused an 11-fold decrease in the anti-adhesive effect. Substitution of the alkyne moiety between C-3 and C-4 by an alkene (B and E) or alkane (D) blocked completely the anti-adhesive effect. Analogs A and I completely blocked superoxide release from eosinophils caused by phorbol-12-myristate-13-acetate or PAF and LTC 4-release caused by fMLP plus cytochalasin B. Change of the alkyne moiety between C-3 and C-4 to an alkene (B and E) or alkane (D) blocked completely these inhibitory effects of phomactin. Analog A decreased the maximal binding of [ 3H]PAF binding to eosinophils without change of the apparent dissociation constant. We conclude that phomactin analogs are specific non-competitive PAF antagonists and have exceptional efficacy in inhibiting adhesion, metabolic activity and leukotriene secretion in human eosinophils. We further define the structural alterations in the phomactin molecule that regulate its inhibitory functions.

Murine granulosa cell morphology and function are regulated by a synthetic Arg–Gly–Asp matrix

Extracellular matrix (ECM) proteins are established regulators of granulosa cell survival, morphology, and differentiation. In this study, the roles of ECM adhesion peptide density on murine granulosa cell adhesion, morphology, and steroid secretion were probed using synthetic matrices. The synthetic matrix was fabricated from the polysaccharide alginate, which does not inherently support cell adhesion but can be modified with controlled densities of adhesion peptides (10 −4 to 2×10 −1 ng/cm 2). GRM02, a murine granulosa cell line, and primary murine granulosa cells were cultured on alginate matrices modified by coupling of synthetic peptide sequences containing the Arg–Gly–Asp motif common to ECM proteins. Cells cultured on these peptide-modified surfaces (0.02, 0.2 ng/cm 2) attached and spread, with morphologies specific to the peptide identity and density. Additionally, progesterone and estradiol secretion was a function of peptide density, with up to threefold increases compared to controls. These results indicate that the density and identity of adhesion peptides regulate granulosa cell function. This system provides a mechanism to examine the granulosa cell-ECM interactions that occur during follicle maturation.

Do Behavioral Interactions between Salamanders and Beetles Indicate a Guild Relationship?

Guilds consist of groups of species that use mutual resources or collections of overlapping resources. Guilds are often comprised of members of the same family or genus, but they can span larger taxonomic categories. Predacious arthropods, such as carabid beetles, centipedes and spiders, and small carnivorous vertebrates, such as woodland salamanders, overlap extensively in microhabitat and prey types. These taxa, though unrelated, may form important guilds of forest floor predators. We examined the behavioral interactions between a carabid ground beetle (Platynus tenuicollis) and a small woodland salamander (the red-backed salamander, Plethodon cinereus) in laboratory encounters. These species occur syntopically and feed on similar prey. Individuals of P. cinereus are territorial and defend cover objects against conspecific and congeneric intruders. Because both species require moist conditions, it seems probable that they would compete for resources, such as cover objects and prey, as the forest floor and leaf litter dries. We posed two general hypotheses: (1) salamanders will display territorial behavior toward intruding salamanders and beetles and (2) beetles will display territorial behavior toward intruding beetles and salamanders. Residents of each species were paired with control, intra- and interspecific intruders. In both species, residency status affected behavior—residents behaving more aggressively than intruders. Resident salamanders behaved similarly toward intruding salamanders and beetles, but no biting was observed. There were no significant differences in aggressive behavior of resident beetles among treatments. When physical attacks by beetles were observed, they were brief and often escalated to biting and chasing. Platynus tenuicollis bit intruders of both species in a significant number of trials; this often resulted in the production of adhesive secretions by P. cinereus that successfully immobilized P. tenuicollis. Antipredator behaviors observed in P. cinereus, and biting by P. tenuicollis of P. cinereus, suggest that intraguild predation may be as important as interspecific resource competition for these species of forest floor predators.

Characterization of the adhesive from cuvierian tubules of the sea cucumber Holothuria forskali (Echinodermata, Holothuroidea).

Sea cucumbers possess a peculiar specialized defense system: the so-called Cuvierian tubules. The system is mobilized when the animal is mechanically stimulated, resulting in the discharge of a few white filaments, the tubules. Their great adhesivity, combined with their high tensile strength, allows Cuvierian tubules to entangle and immobilize potential predators. The cellular origin and composition of the Cuvierian tubule adhesive were investigated in the species Holothuria forskali by studying prints left on the substratum after mechanical detachment of the tubule. Polyclonal antibodies raised against tubule print material were used to locate the origin of tubule print constituents in the tubules. Extensive immunoreactivity was detected in the secretory granules of mesothelial granular cells, suggesting that their secretions make up the bulk of the adhesive material. Tubule print material consists of 60% proteins and 40% carbohydrates, a composition that is unique among the adhesive secretions of marine invertebrates. Although it is highly insoluble, a small fraction of this material can be extracted using denaturing buffers. Electrophoretic analysis of the extracts revealed that it contains about 10 proteins with apparent molecular masses ranging from 17 to 220 kDa and with closely related amino acid compositions, rich in acidic and in small side-chain amino acids. The adhesive from the Cuvierian tubules of H. forskali shares these characteristics with many marine bioadhesives and structural biomaterials.

Morphology and albumin secretion of adult rat hepatocytes cultured on a hydrophobic porous expanded polytetrafluoroethylene membrane

Primary culture of rat hepatocytes was performed on a hydrophobic porous expanded polytetrafluoroethylene (ePTFE) membrane incorporated into the base of a culture dish. Two types of ePTFE membranes, a uniaxially expanded type (ePTFE-1) and a biaxially expanded type (ePTFE-2), could be used as the culture surfaces for hepatocytes. The formation of multicellular aggregates was observed in the culture dish when each membrane type was used. A pore size of 1 μm or higher was adequate for cell adhesion and albumin secretion for both membrane types. The activity of albumin secretion in the dish with the ePTFE membrane was markedly higher than that in the polystyrene dish. Spheroidal multicellular aggregates (spheroids) were observed when hepatocytes were cultured on the ePTFE-1 membrane. The ePTFE-1 membrane maintained the albumin secretion activity for a longer period than the non-expanded PTFE film. It was assumed that the cooperative action of membrane structure and oxygen permeability promoted the formation of cell aggregates and increased the albumin secretion activity.

An Integrative Study of Insect Adhesion: Mechanics and Wet Adhesion of Pretarsal Pads in Ants

Many animals that locomote by legs possess adhesive pads. Such organs are rapidly releasable and adhesive forces can be controlled during walking and running. This capacity results from the interaction of adhesive with complex mechanical systems. Here we present an integrative study of the mechanics and adhesion of smooth attachment pads (arolia) in Asian Weaver ants (Oecophylla smaragdina). Arolia can be unfolded and folded back with each step. They are extended either actively by contraction of the claw flexor muscle or passively when legs are pulled toward the body. Regulation of arolium use and surface attachment includes purely mechanical control inherent in the arrangement of the claw flexor system.Predictions derived from a 'wet' adhesion mechanism were tested by measuring attachment forces on a smooth surface using a centrifuge technique. Consistent with the behavior of a viscid secretion, frictional forces per unit contact area linearly increased with sliding velocity and the increment strongly decreased with temperature.We studied the nature and dimensions of the adhesive liquid film using Interference Reflection Microscopy (IRM). Analysis of 'footprint' droplets showed that they are hydrophobic and form low contact angles. In vivo IRM of insect pads in contact with glass, however, revealed that the adhesive liquid film not only consists of a hydrophobic fluid, but also of a volatile, hydrophilic phase. IRM allows estimation of the height of the liquid film and its viscosity. Preliminary data indicate that the adhesive secretion alone is insufficient to explain the observed friction and that rubbery deformation of the pad cuticle is involved.

Preliminary characterisation and extraction of anterior adhesive secretion in monogenean (platyhelminth) parasites.

Secreted anterior adhesives, used for temporary attachment to epithelial surfaces of fishes (skin and gills) by some monogenean (platyhelminth) parasites have been partially characterised. Adhesive is composed of protein. Amino acid composition has been determined for seven monopisthocotylean monogeneans. Six of these belong to the Monocotylidae and one species, Entobdella soleae (van Beneden et Hesse, 1864) Johnston, 1929, is a member of the Capsalidae. Histochemistry shows that the adhesive does not contain polysaccharides, including acid mucins, or lipids. The adhesive before secretion and in its secreted form contains no dihydroxyphenylalanine (dopa). Secreted adhesive is highly insoluble, but has a soft consistency and is mechanically removable from glass surfaces. Generally there are high levels of glycine and alanine, low levels of tyrosine and methionine, and histidine is often absent. However, amino acid content varies between species, the biggest differences evident when the monocotylid monogeneans were compared with E. soleae. Monogenean adhesive shows similarity in amino acid profile with adhesives from starfish, limpets and barnacles. However, there are some differences in individual amino acids in the temporary adhesive secretions of, on the one hand, the monogeneans and, on the other hand, the starfish and limpets. These differences may reflect the fact that monogeneans, unlike starfish and barnacles, attach to living tissue (tissue adhesion). A method of extracting unsecreted adhesive was investigated for use in further characterisation studies on monogenean glues.

The effect of titanium surface roughness on the adhesion of monocytes and their secretion of TNF-alpha and PGE2.

Dental implant surfaces are important in determining the tissue/surface interaction. One of the first cells to adhere to the implant surface is the monocyte. This study examines the effect of surface roughness on monocyte adhesion and cytokine secretion. Monocyte adherence to titanium discs of 4 different degrees of surface roughness and plastic surfaces was assayed. Blood mononuclear cells were incubated for 1.5 h in 16 mm culture wells into which titanium discs had been placed. Non-adherent cells were washed off and the numbers of remaining adherent monocyte determined by DNA quantification. TNF-alpha and PGE2 secretion in media from overnight cultures of attached monocytes stimulated with lipopolysaccharide (LPS) was quantified using ELISA and RIA, respectively. Monocyte adherence to rough titanium surfaces was greater than to turned titanium surfaces, while the lowest adherence was to the plastic surface. No significant differences in adherence to 250, 75 or 25 microm blasted surfaces could be detected. The number of adherent monocytes increased with time, with maximum adhesion after 2 h of incubation. Incubation of monocytes adherent to titanium surfaces resulted in a decrease of less than 30% in their numbers over 7 days, whereas cells attached to plastic surfaces decreased to non-detectable numbers after 48 h. Porphyromonas gingivalis LPS stimulation upregulated TNF-alpha and PGE2 secretion into the media. The LPS-induced TNF-alpha and PGE2 secretion was independent of the titanium surface roughness, however the lowest amounts of TNF-alpha and PGE2 were secreted from cells attached to plastic surfaces. The results of this study indicate that the number of monocytes attached to blasted titanium surfaces is significantly greater than to machined titanium surfaces. PGE2 and TNF-alpha secretion is less influenced by titanium surface roughness.

Alpha(v)beta(3) integrin engagement modulates cell adhesion, proliferation, and protease secretion in human lymphoid tumor cells.

The mechanisms used by human lymphoproliferative diseases to invade locally and metastasize are thought to be similar to those developed by solid tumors, including cell proliferation and secretion of extracellular matrix-degrading enzymes following adhesion to extracellular matrix proteins. Hence, the ability of Namalwa (Burkitt's lymphoma), U266 (multiple myeloma), and CEM (T-cell lymphoblastic leukemia) cells to interact with the extracellular matrix components vitronectin and fibronectin was determined. Fresh bone marrow plasma cells from patients with multiple myeloma also were studied. Engagement of alpha(v)beta(3) integrin, formation and protein composition of focal adhesion contacts on the cell surface, phosphorylation of several signal transduction proteins in the contacts, cell proliferation, and enzyme secretion were studied following adhesion to vitronectin and fibronectin. All three lines adhered to immobilized vitronectin and fibronectin. Adhesion was fully prevented by neutralizing monoclonal anti-alpha(v)beta(3) integrin antibody. Integrin engagement caused the formation of phosphorylated pp60(src)/focal adhesion kinase complexes and the aggregation of focal adhesion plaques containing the beta(3) integrin subunit, the cytoskeletal proteins vinculin, cortactin, and paxillin, the tyrosine kinases focal adhesion kinase and pp60(src), the adapter protein Grb-2, and the mitogen-activated protein kinase ERK-2. Free and immobilized vitronectin and fibronectin stimulated the proliferation of cells under serum-free conditions and the production and release of urokinase-type plasminogen activator, and increased the release of the activated forms of matrix metalloproteinase-2 and matrix metalloproteinase-9 in an alpha(v)beta(3) integrin-dependent manner. Similar results were obtained in myeloma plasma cells. The demonstrated ability of lymphoid tumor cells to interact with the extracellular matrix components vitronectin and fibronectin via alpha(v)beta(3) integrin can be interpreted as evidence of a novel mechanism for their invasion and spreading. This interaction allows them to adhere to the substratum and enhances their proliferation and protease secretion.

Autocrine motility factor enhances hepatoma cell invasion across the basement membrane through activation of β1 integrins

Autocrine motility factor/phosphohexose isomerase (AMF/PHI) is a cytokine that is linked to tumor invasion and metastasis. In hepatocellular carcinoma (HCC) tissues, hepatoma cells produce AMF/PHI and its receptor, Mr 78,000 glycoprotein (gp78), is strongly detected in hepatoma cells invading into the stroma and tumor thrombi in the portal vein. Here, we investigated the mechanism of hepatoma cell invasion through Matrigel induced by AMF/PHI using 3 hepatoma cell lines. Production of AMF/PHI, phosphorylation of MEK1/2, and Rho activity were investigated by immunoblotting. Expression of AMF/PHI and gp78 was observed by confocal fluorescence microscopy. The influence of AMF/PHI on activated integrin β1 subunit expression was evaluated by flow cytometry. Changes in invasion, adhesion, and motility induced by AMF/PHI were evaluated using chemoinvasion, adhesion, and phagokinetic track motility assays. The effect of AMF/PHI on matrix metalloproteinase (MMP) secretion was evaluated by gelatin zymography. Hepatoma cells produced AMF/PHI and expressed gp78. Although AMF/PHI was ubiquitously detected, gp78 was strongly expressed in migrating cells. AMF/PHI induced up-regulation of activated integrin β1 subunit expression. AMF/PHI stimulated hepatoma cell invasion through Matrigel, and stimulated the adhesion, motility, and MMP-2 secretion of hepatoma cells. The latter effects were suppressed by the function-blocking antibody for integrin β1 subunit. AMF/PHI also enhanced Rho activity and the phosphorylation of MEK1 and MEK 2. Our results indicate that AMF/PHI enhances hepatoma cell invasion through Matrigel in an autocrine manner by stimulating the adhesion, motility, and MMP-2 secretion of these cells through activation of β1 integrins. (HEPATOLOGY 2001;34:62-71.)

Effect of calcium ionophores on early development in fucoid algae

SUMMARY Although much studied, the role of Ca2+ in early fucoid development remains unclear. One technique to investigate Ca2+ function that has not been fully exploited is the use of ionophores to drastically increase cytosolic Ca2+ activity. We have therefore conducted an analysis of the effects of uniform application of the Ca2+ ionophores, A23187 and ionomycin, on early development of fucoid algae. Both ionophores had substantially the same effects. Cell adhesive secretion, rhizoid growth and negative phototropism were reduced but not abolished by ionophore treatment, and germination was delayed. One plausible interpretation of these data is that secretion is partially compromised in the treated zygotes. Surprisingly, photopolarization and cytokinesis were unaffected, indicating that Ca2+ homeostasis may not be required for these processes.

Morphine inhibits indolactam V-induced U937 cell adhesion and gelatinase secretion.

We demonstrate that indolactam V, a non-phorbol protein kinase C activator, promotes U937 cell attachment to fibronectin, type IV collagen and laminin. In the absence of indolactam V, 2-4% of U937 cells attach to all test substrates, however, in the presence of 100 nM indolactam V, 25, 16 and 11% of U937 cells attach to fibronectin, type IV collagen and laminin, respectively. When added concomitantly, 90 microM H-7, a protein kinase C inhibitor, reduces indolactam V-induced U937 cell adhesion to fibronectin by 91%. Monoclonal antibodies directed against both the beta1 and alpha 5 integrin subunits inhibit indolactam V-induced U937 cell adhesion to fibronectin by 62 and 52%, respectively. Indolactam V also promotes homotypic aggregation in U937 cells, which is blocked with either anti-ICAM or anti-LFA-1 antibodies. In addition, indolactam V promotes U937 cell secretion of a 92 kDa gelatinase as demonstrated by zymography. In the presence of low levels of morphine (10 nM-1.0 microM), the U937 cell attachment to matrix proteins was not significantly affected. However, in the presence of 10 microM morphine, the indolactam V treated cells exhibit a 71-74% reduction in cell adhesion to the matrix proteins. Further, 10 microM morphine also blocks indolactam V-induced homotypic aggregation and gelatinase secretion. The inhibitory effect of morphine on cell-matrix adhesion and gelatinase secretion was not inhibited by the opiate receptor antagonist naloxone (1 microM). While 10 microM naloxone did partially counteract the effect of 10 microM morphine on U937 cell attachment, this effect was likely non-specific since 10 microM naloxone alone increased cell adhesion. Supporting this conclusion, PCR analysis revealed that U937 cells do not express the mu high affinity morphine receptor. Also, indolactam V did not induce mu receptor expression, suggesting that morphine acts on U937 cells in a non-specific fashion.

La thérapie cellulaire dans ses applications cliniques

Articular cartilage has a very poor capacity for repair. In order to get a normal functional efficacy, the replaced tissue has to reproduce the structure, composition and physico-chemical properties of native cartilage tissue. The transplantation of cultured autologous chondrocytes into chondral defects is currently applicable only in the case of young sportive people with a limited lesion in an otherwise relatively normal joint. Recent experimental studies have shown that pluripotent mesenchymal cells from bone marrow could also repair experimental osteochondral defects. An advantage of this grafting procedure is that large areas of cartilage surface could be covered. Bone marrow cells are not so difficult to get, they have a high potency to divide and they can develop in vitro as chondrogenic, osteogenic or adipogenic cells. The present ways of research are: to characterize one or several growth factors capable to specifically induce the chondrogenic lineage; to determine nutrient and environmental conditions allowing the cultured chondrogenic cells to undergo a maturation process within the cell pellet; to elaborate three-dimensional synthetic, biodegradable polymeric scaffolds assessed with respect to chondrogenic cell adhesion, proliferation, maturation and cartilage matrix secretion; finally, to elaborate a mixed biomaterial composed of chondrogenic and osteogenic cells selectively distributed within polymeric scaffolds in order to get a better adherence of the implanted cells to the lesion sites.

Ultrastructural aspects of the ovarian follicle and egg envelope of the sea‐grass goby Zosterisessor ophiocephalus (Osteichthyes, Gobiidae)

The development of the ovarian follicle, the chorion, the attaching filaments apparatus, and the egg surface are described in the grass goby Zosterisessor ophiocephalus by transmission and scanning electron microscopy. The first appearance of the zona radiata externa is followed by the apposition of a canalicular layer in the outer zona radiata interna, and then of a fibrous tangential network in the inner zona radiata interna, reaching an overall thickness of 5.6 μm in mature eggs. Both zona radiata interna components are likely secreted by the oocyte, whereas the apparently mucopolysaccharidic zona radiata externa is produced early by flattened granulosa cells. During maturation, granulosa cells become cubic in cross section and elongate from the animal pole, marked by the prospective micropyle and oriented along the oocyte meridians. Their cytoplasm is markedly engulfed with enlarged cisternae of the rough endoplasmic reticulum involved, together with mitochondria and well‐developed Golgi complexes, in adhesive filaments protein matrix secretion and the making of the basal plate. Filament matrix aggregates in the granulosa cells intercellular spaces, where it is confined by intercellular junctions. The basal plate is hollow in the centre surrounding the micropylar pit and supports a cribriform column of netted filaments eventually fraying off and becoming the egg adhesive apparatus. The comparative functional and systematic relevance of these features among teleosts is discussed and related to environmental and life style adaptations.

Adhesive secretions in the platyhelminthes

This review is the first to draw together knowledge about bioadhesives secreted by a group of parasites. Mechanisms of mechanical attachment are well known among parasites, but some can also attach to host surfaces by chemical means using a thin layer of adhesive material secreted at the parasite-host interface. Attachment by adhesives to living surfaces has not been studied in detail previously. A significant volume of research has determined much about the chemistry and nature of bioadhesives secreted by various marine macroinvertebrates from different phyla for attachment to inert substrates. Mussels and barnacles are sessile and adhere permanently, whereas starfish display temporary but firm adhesion during locomotion, feeding and burrowing. We focus on the Platyhelminthes that comprises the largely free-living Turbellaria and the wholly parasitic Monogenea, Cestoda, Digenea and Aspidogastrea. The term tissue adhesion is introduced to describe attachment by adhesives to epithelial surfaces such as fish epidermis and the lining of the vertebrate gut. These living layers regenerate rapidly, secrete mucus, are a site for immune activity and are therefore especially hostile environments for organisms that inhabit them, presenting a significant challenge for adhesion. Not all platyhelminths adhere to living surfaces and types of adhesion to inert substrates by the free-living turbellarians are also reviewed. Tissue adhesion is particularly well exemplified by monopisthocotylean monogeneans, parasites that are especially mobile as larvae, juveniles and adults on the epidermis of the body and gill surfaces of fish. These monogeneans secrete adhesives from the anterior end when they move from site to site, but some have secondarily developed adhesives at the posterior end to supplement or replace mechanical attachment by hooks and/or by suction. The temporary but tenacious anterior adhesives of monogeneans display remarkable properties of instant attachment to and detachment from their host fish surfaces. In contrast to the mobility of turbellarians and monopisthocotylean monogeneans and the simplicity of their direct life cycles, the largely endoparasitic Cestoda and Digenea are considered to be less mobile as adults. The complex cestode and digenean life cycles, involving intermediate hosts, place different demands on their various stages. Diverse, mostly anterior, gland cells in larvae, metacestodes and adults of the true tapeworms (Eucestoda), and in larval and adult Gyrocotylidea and Amphilinidea are reviewed. Conspicuous gland cells, mostly but not exclusively at the anterior end, in miracidia, cercariae and adults of digeneans and in cotylocidia and adults of aspidogastreans are also reviewed. Unlike turbellarians and monogeneans, accounts of unequivocal adhesive secretions in the Cestoda, but especially in the Digenea and Aspidogastrea, are relatively rare. The primary purpose of many conspicuous glands in the different stages of these mostly endoparasitic flatworms is for penetration into, or escape from, different hosts in their life cycle. We provide a detailed review of current knowledge about adhesion (in the sense of a thin layer of chemical material) in the Platyhelminthes including uses among eggs, larval, juvenile and adult stages. Information on structure, morphology and ultrastructure of the various adhesive systems that have been described is reviewed. Application of the 'duo gland' model is discussed. Comparisons are made between the little that is known about the chemistry of flatworm adhesives and the significant knowledge of the chemical nature of other invertebrate bioadhesives, especially those from marine macroinvertebrates. The potential importance of adhesives in parasitism is discussed. (ABSTRACT TRUNCATED)