New lectins and other putative adhesins in Aeromonas hydrophila

The ability of strains of Aeromonas hydrophila to bind 125I-labelled collagen types I and IV, fibronectin, laminin, lactoferrin, and immobilized mucins and orosomucoid on latex beads was found to be a property common to all the isolated strains. The binding was specific, was inhibited by homologous unlabelled glycoproteins, and was protease sensitive. The nature of the binding is discussed.     

Membrane interiorization by phagocytosing macrophages — an ultrastructural morphometric approach

Summary Stereological methods have been used to quantify selected membrane compartments of normal and activated rat peritoneal macrophages, before and after phagocytosis of latex beads. Despite being rounder, activated cells are more efficient phagocytes: 30 min after latex challenge they suffer a greater nett depletion of plasma membrane and sequester more and larger phagocytic vacuoles. However, phagocytosis of latex is not the major route of membrane interiorization.We wish to thank Professor R. Barer for his advice and criticism. The work was undertaken by L.O. as a research project in partial fulfilment of requirements for a B.Sc. degree in Human Biology and Anatomy, University of Sheffield.     

Participation of microtubules and microfilaments in the transcellular biliary secretion of immunoglobulin A in primary cultures of rat hepatocytes

Summary The biliary secretion of immunoglobulin A (IgA) in primary hepatocyte cultures was investigated by means of immunofluorescence. The characteristic accumulation of IgA in visible bile canaliculi was found to be strongly inhibited by vinblastine and colchicine or by cytochalasin B, but its surface binding was not.The author thanks Prof. Dr D. Mecke for his support and encouragement. The excellent technical assistance of Mrs M. Behringer and Mrs A. Schneck is gratefully acknowledged. The author is grateful to the BIOTEST Serum Institut (Frankfurt) for the kind gift of human IgA. This work was supported by the Deutsche Forschungsgemeinschaft.     

Microtubule inhibitors block the morphological changes induced in Drosophila blood cells by a parasitoid wasp factor

The shape change of Drosophila melanogaster blood cells (lamellocytes) from discoidal to bipolar that is caused by a factor from the female parasitoid Leptopilina heterotoma is blocked by the tubulin inhibitors vinblastine and vincristine in vitro. The actin inhibitor, cytochalasin B, causes arborization of Drosophila lamellocytes and acts synergistically with the wasp factor to alter lamellocyte morphology. Lamellocyte aborization induced by cytochalasin B is blocked by simultaneous treatment with vinblastine. These observations indicate that the changes in lamellocyte shape induced by both the wasp factor and cytochalasin B require microtubule assembly.     

Action of ACTH,cAMP and cytochalasin B on steroid production by Y-1 mouse adrenal tumor cells in culture

Summary Continued incubation of Y-1 mouse adrenal tumor cells with adrenocorticotrophic hormone (ACTH) or with dibutyryl-3,5-cyclic adenosine monophosphate (dbcAMP) resulted in an initial increase and a subsequent decrease in steroidogenesis. ACTH-or dbcAMP-stimulated steroidogenesis was inhibited by cytochalasin B (CB) to approximately the same extent during the entire period of incubation; CB inhibition of the ACTH response was reversible.Supported in part by NTSU Faculty Research grant No. 34711, and NIA No. AG01055-02A1.Acknowledgment is made for the assistance of L. Hershberger, J. Youngblood and V. Dang; K. Mrotek, K. Johansson and M. Donahue were editors.     

Chemotaxis of rabbit macrophages in vitro: Inhibition by drugs

Summary Chemotaxis of rabbit macrophages was inhibited in vitro by phenylbutazone and sodium salicylate, but not by other antiinflammatory agents. Other inhibitory compounds were colchicine, vincristine, PHA, Con A, iodoacetic acid, cytochalasin B, and EDTA. Some of these in vitro results contrast apparently with in vivo effects.     

Microtubule inhibitors block the morphological changes induced inDrosophila blood cells by a parasitoid wasp factor

Summary The shape change ofDrosophila melanogaster blood cells (lamellocytes) from discoidal to bipolar that is caused by a factor from the female parasitoidLeptopilina heterotoma is blocked by the tubulin inhibitors vinblastine and vincristine in vitro. The actin inhibitor, cytochalasin B, causes arborization ofDrosophila lamellocytes and acts synergistically with the wasp factor to alter lamellocyte morphology. Lamellocyte arborization induced by cytochalasin B is blocked by simultaneous treatment with vinblastine. These observations indicate that the changes in lamellocyte shape induced by both the wasp factor and cytochalasin B require microtubule assembly.     

肝癌细胞系Hep3B中CD133+细胞亚群的分离及其特性的研究

目的研究CD133在人肝癌细胞系Hep3B中的表达以及CD133+细胞的体外增殖、自我更新及体内成瘤能力,初步探讨肝癌中CD133+细胞亚群的干细胞特性。方法流式细胞仪检测未分选的Hep3B细胞中CD133+细胞表达情况;免疫磁珠分选技术纯化CD133+肿瘤细胞;MTT法检测CD133+细胞体外增殖能力;无血清培养纯化...     

The pharmacological relevance of vital staining with neutral red

Summary The uptake of neutral red into the renin-containing juxtaglomerular granules does not inhibit the release of renin either in basal or in stimulated states of renin secretion. The vasodilating effect of neutral red may be due to a non-specific binding to noradrenaline-receptors in the vascular smooth muscle cells.This work was supported by the German Research Foundation within the SFB 90 Cardiovasculäres System.     

Cells secreting antibodies originate from cells secreting immunoglobulins without a detectable antibody function for the antigen injected]

Cells secreting immunoglobulins without detectable antibody function arising after an injection of horseradish peroxidase were micromanipulated from the center of haemolytic plaques of Sheep red blood cells coated with anti-Ig antibodies. These cells were cultured individually for 48 hrs, with irradiated cells as feeder layer and in the presence of the immunogen and of LPS. It was shown that after this time 22% of the immunoglobulin-secreting cells had generated antiperoxidase antibody-secreting cells or were transformed into antibody-secreting cells.     

Comparison of the effects of illumination on the melanophores of intact and eyestalkless fiddler crabs, Uca pugilator, and inhibition of the primary response by cytochalasin B.

Approximately 100 times more illumination is required to produce pigment dispersion in the melanophores of eyestalkless fiddler crabs (Uca pugilator) than in the melanophores of intact crabs. The pigment in melanophores of isolated legs will normally disperse in response to irradiation, but this response is inhibited by cytochalasin B.     

An agglutinin with unique specificity for N-glycolyl sialic acid residues of thyroglobulin in the hemolymph of a marine crab Scylla serrata (Forskal).

A novel agglutinin with specificity for sialic acid sequence of sugars in thyroglobulin is identified in the hemolymph of Scylla serrata. The physico-chemical characteristics of its binding affinity, such as pH and temperature optima, and cationic requirements are defined. N-glycolyl neuraminic acid (NeuGc) (at 0.6 mM), in contrast to N-acetyl neuraminic acid (NeuAc) (at greater than 5.0 mM), is the potent inhibitor of hemagglutination. Bovine and porcine thyroglobulins containing NeuGc, inhibited the agglutination. NeuGc-acid glycoprotein fraction (bovine) but not NeuAc-acid glycoprotein fraction (human) inhibited the hemagglutination. The inability of other NeuGc-glycoproteins (bovine submaxillary mucin) to inhibit the agglutination suggests that the agglutinin may also recognize glycosidic linkage associated with NeuGc. The potential of the agglutinin in identifying NeuGc containing human tumor associated antigens is discussed.     

Effect of periodate oxidation of glycoconjugates of lymphocyte membranes on the immune response in vitro]

Mouse spleen cells treated with sodium periodate for 10 min. at 4 degrees C are stimulated to undergo blastogenesis and to incorporate thymidine. The effect of such treatment on the antibody response in vitro induced by Sheep red blood cells has been evaluated. Periodate-induced proliferation is accompanied by a marked inhibition of the immune response to this antigen. At concentrations leading to mitogenesis, no cytotoxic effect of periodate was observed and treated cells survived well on tissue culture. Cell recoveries from samples treated with periodate at the optimal mitogenic dose, were markedly enhanced when harvested at different days after culturing wheras lower antibody forming cells numbers wereconsistently observed during the culture period.     

An agglutinin with unique specificity for N-glycolyl sialic acid residues of thyroglobulin in the hemolymph of a marine crabScylla serrata (Forskal)

A novel agglutinin with specificity for sialic acid sequence of sugars in thyroglobulin is identified in the hemolymph ofScylla serrata. The physico-chemical characteristics of its binding affinity, such as pH and temperature optima, and cationic requirements are defined. N-glycolyl neuraminic acid (NeuGc) (at 0.6 mM), in contrast to N-acetyl neuraminic acid (NeuAc) (at >5.0 mM), is the potent inhibitor of hemagglutination. Bovine and porcine thyroglobulins containing NeuGc, inhibited the agglutination. NeuGc-acid glycoprotein fraction (bovine) but not NeuAc-acid glycoprotein fraction (human) inhibited the hemagglutination. The inability of other NeuGc-glycoproteins (bovine submaxillary mucin) to inhibit the agglutination suggests that the agglutinin may also recognize glycosidic linkage associated with NeuGc. The potential of the agglutinin in identifying NeuGc containing human tumor associated antigens is discussed.     

Comparison of the effects of illumination on the melanophores of intact and eyestalkless fiddler crabs,Uca pugilator,and inhibition of the primary response by cytochalasin B

Summary Approximately 100 times more illumination is required to produce pigment dispersion in the melanophores of eyestalkless fiddler crabs (Uca pugilator) than in the melanophores of intact crabs. The pigment in melanophores of isolated legs will normally disperse in response to irradiation, but this response is inhibited by cytochalasin B.This investigation was supported by a Faculty Research Grant from Western Kentucky University toT. P. Coohill and by Grant No. GB-27497 toM. Fingerman from the National Science Foundation.     

Stimulation of human chorionic gonadotropin and progesterone secretion by tumor promoters,phorbol ester and teleocidin B,in cultured choriocarcinoma cells

Summary Both 12-O-tetradecanoyl-phorbol-1-acetate and teleocidin B stimulated the secretion of human chorionic gonadotropin by cultured choriocarcinoma cells. These tumor promoters also stimulated production of progesterone in the cells. However, the 2 tumor promoters did not exert a marked effect on the cellular binding of epidermal growth factor that also had a stimulatory effect on production of these hormones.     

Role of serum components in the binding and phagocytosis of oxidatively damaged erythrocytes by autologous mouse macrophages

To investigate the role of autologous serum components in the recognition of damaged cells by macrophages, we examined the binding and phagocytosis of damage oxidatively damaged red blood cells with Cu2+ and ascorbate (oxRBCs) by autologous resident mouse peritoneal macrophages. The binding of oxRBCs by macrophages was independent of the presence of serum. However, phagocytosis by macrophages increased with serum concentration, and macrophages showed little ingestion of oxRBCs in a serum-free medium. Macrophages neither bound nor appreciably ingested native RBCs (before oxidation) in either the absence or presence of autologous serum. Mouse macrophages ingested significantly more native as well as oxRBCs in the presence of heat-inactivated fetal calf serum than in the presence of heat-inactivated mouse serum. Pretreated oxRBCs with normal serum were rarely ingested by macrophages in a serum-free medium. Phagocytosis of oxRBCs was significantly inhibited by depletion of IgG or calcium from serum, by heat inactivation of complement, or by antiserum against mouse C3. These results demonstrate that serum components such as IgG, C3, and calcium are involved in phagocytosis of oxRBCs by autologous macrophages.     

Presence of benzodiazepine binding sites (receptors) and amplification thereof by imprinting in Tetrahymena

Live Tetrahymena cells bound 3H-diazepam specifically, as demonstrated by autoradiographic evidence of displacement of about 25% of labeled diazepam in the presence of a 1000-fold amount of cold diazepam. The 3H-diazepam bound to membrane preparations isolated from untreated (control) cells was not displaced by cold diazepam, whereas cells involved in primary interaction (imprinting) with diazepam showed amplification and specificity of diazepam binding in both in vivo (cell suspension) and in vitro (pellicle) systems, as well as displacement of bound label in the presence of 1000-fold cold diazepam. It appears that diazepam induced imprinting and, consequently, also the formation of specific receptors in Tetrahymena.     

Isolation of peptides blocking the function of anti-apoptotic Livin protein

Livin (ML-IAP) is a cancer-associated member of the inhibitor of apoptosis protein (IAP) family. By yeast two-hybrid screening of a randomized peptide expression library, we isolated short linear peptides that specifically bind to Livin, but not to other IAPs. Intracellular expression of the peptides sensitized livin-expressing cancer cells toward different pro-apoptotic stimuli. The bioactive peptides neither showed sequence homologies to Smac-derived IAP inhibitors, nor did they interfere with the binding of Livin to Smac. Intracellular expression of the peptides did not affect the levels or the subcellular distribution of Livin. Growth of livin-expressing tumor cells was inhibited in colony formation assays by the Livin-targeting peptides. These findings provide evidence that the targeted inhibition of Livin by peptides represents a viable approach for the apoptotic sensitization and growth inhibition of tumor cells. The inhibitory peptides isolated here could form a novel basis for the development of therapeutically useful Livin inhibitors.