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At least 1,279 records · Page 71Linked to original sources
PubMed2003

Effects of testosterone undecanoate as a male contraceptive candidate on rat immunological features.

Testosterone undecanoate (TU) is under phase III clinical trial as a hormonal male contraceptive in China. Sex hormones can modulate the immune system. Female hormonal contraceptives may affect SIV/HIV-1 transmission. To evaluate the safety of TU and to understand whether long-term use of TU for a male contraceptive affects users' immunological features, adult male rats were treated for a 32-week TU-treated phase at the dose of 20 mg TU/kg body weight and a 24-week recovery phase. The reproductive and immunological parameters of 4-6 rats in each subgroup were examined at the stated time point. The mean sperm count and viability in the treated rats were significantly suppressed (p < 0.01). In the TU-treated group: the mean blood leukocyte and lymphocyte counts; the proliferation indexes of T cells from peripheral blood mononuclear cells (PBMC) and spleen; and, of B cells from spleen, as well as the mean counts of blood T, NK, and B cells decreased in comparison with those of control group. These decreases were not significant (p > 0.01). Similarly, the mean serum IgM, IgG, and IgA levels and complement activity in TU-treated rats were lower than those in control group (p > 0.01), and the changes in the antibody levels of the examined genital secretions were not significant (p > 0.01). The changes in the thickness of urethra epithelium, and in secretory component (SC) expression in genitals were not observed in the treated group. These results demonstrated that long-term supraphysiological TU injection did not obviously affect the examined rat immunological parameters.

Animals↗
PubMed1994

Phorbol myristate acetate-mediated stimulation of transcytosis and apical recycling in MDCK cells.

We observed that phorbol myristate acetate (PMA) stimulates transcytosis of the polymeric immunoglobulin receptor (pIgR) in MDCK cells. Apical release of pre-endocytosed ligand (dimeric IgA) bound to the pIgR can be stimulated twofold within 7 min of addition of PMA while recycling of the ligand from the basal surface is not affected. In addition, apical surface delivery of pIgR and cleavage of its ectodomain to secretory component (SC) is also stimulated by PMA. The recycling of apically internalized ligand back to the apical surface is similarly stimulated. These results suggest that the stimulation of apical delivery is from an apical recycling compartment. The effect of PMA suggests that protein kinase C (PKC) is involved in the regulation of pIgR trafficking in MDCK cells. To test this we down regulated PKC activity by pre-treating cells with PMA for 16 h and observed that transcytosis could no longer be stimulated by PMA. Western blots show that the PKC isozymes alpha and to a lesser extent epsilon, are depleted from MDCK cells which have been pre-treated with PMA for 16 h and that treatment of MDCK cells with PMA for 5 min causes a dramatic translocation of the PKC alpha isozyme and a partial translocation of the epsilon isozyme from the cytosol to the membrane fraction of cell homogenates. This translocation suggests that the alpha and/or epsilon isozymes may be involved in PMA mediated stimulation of transcytosis. A mutant pIgR in which serines 664 and 726, the major sites of phosphorylation, are replaced by alanine is stimulated to transcytose by PMA, suggesting that phosphorylation of pIgR at these sites is not required for the effect of PMA. These results suggest that PMA-mediated stimulation of pIgR transcytosis may involve the activation of PKC alpha and/or epsilon, and that this stimulation occurs independently of the major phosphorylation sites on the pIgR. Finally, PMA stimulates transcytosis of basolaterally internalized transferrin, suggesting that PMA acts to generally stimulate delivery of endocytosed proteins to the apical surface.

Animals↗
PubMed1977

Studies of the secretory process in the mammalian exocrine pancreas. I. The condensing vacuoles.

Phosphatase cytochemistry was used to distinguish between the Golgi apparatus and GERL (considered as a specialized region of endoplasmic reticulum [ER] at the inner [trans] aspect of the Golgi stack) in pancreatic exocrine cells of guinea pig, rat, rabbit, and hamster. The trans element of the Golgi stack exhibits thiamine pyrophosphatase (TPPase) but no acid phosphatase (AcPase) activity. In contrast, GERL shows AcPase but no TPPase activity. The nascent secretory granules, or condensing vacuoles, are expanded cisternal portions of GERL. Continuities of condensing vacuoles with rough ER are suggested, and it is proposed that some secretory components may have direct access to the condensing vacuoles from ER. Connections of Golgi apparatus with GERL were not seen.

Acid Phosphatase↗
PubMed1984

Structural and functional polarity of canalicular and basolateral plasma membrane vesicles isolated in high yield from rat liver.

A method has been developed for routine high yield separation of canalicular (cLPM) from basolateral (blLPM) liver plasma membrane vesicles of rat liver. Using a combination of rate zonal floatation (TZ-28 zonal rotor, Sorvall) and high speed centrifugation through discontinuous sucrose gradients, 9-16 mg of cLPM and 15-28 mg of blLPM protein can be isolated in 1 d. cLPM are free of the basolateral markers Na+/K+-ATPase and glucagon-stimulatable adenylate cyclase activities, but are highly enriched with respect to homogenate in the "canalicular marker" enzyme activities leucylnaphthylamidase (48-fold), gamma-glutamyl-transpeptidase (60-fold), 5'-nucleotidase (64-fold), alkaline phosphatase (71-fold), Mg++-ATPase (83-fold), and alkaline phosphodiesterase I (116-fold). In contrast, blLPM are 34-fold enriched in Na+/K+-ATPase activity, exhibit considerable glucagon-stimulatable adenylate cyclase activity, and demonstrate a 4- to 15-fold increase over homogenate in the various "canalicular markers." cLPM have a twofold higher content of sialic acids, cholesterol; and sphingomyelin compared with blLPM. At least three canalicular-(130,000, 100,000, and 58,000 mol wt) and several basolateral-specific protein bands have been detected after SDS PAGE of the two LPM subfractions. Specifically, the immunoglobin A-binding secretory component is restricted to blLPM as demonstrated by immunochemical techniques. These data indicate virtually complete separation of basolateral from canalicular LPM and demonstrate multiple functional and compositional polarity between the two surface domains of hepatocytes.

Animals↗
PubMed1971

Further studies on the ultrastructure of dimeric IgA of human origin.

Human colostral IgA and myeloma dimer IgA were purified and examined in the electron microscope using a modified technique of negative staining. Both types of preparation contained double Y-shaped structures of the dimensions: Fab region, 35 x 70 A, and the sum of the two Fc regions, 40 x 140-155 A. Colostral IgA as well as myeloma dimer IgA molecules showed a tendency of bending at the point where the Fc regions joined. Secretory component bound to dimer IgA produced no visible alteration of the molecule. Mild reduction and alkylation of colostral IgA yielded single Y-shaped 7S monomers with the dimensions, Fab, 35 x 70 A, and Fc, 40 x 65-70 A.

Alkylation↗
PubMed1971

Regulation of the immune response: suppressive and enhancing effects of passively administered antibody.

The ability of passively administered antibody to suppress the immune response against homologous antigenic determinants while concomitantly enhancing the response against other unrelated determinants of the same antigen molecule has been established in two distinct antigen-antibody systems: (a) guinea pig gamma(2)-immunoglobulin + passive anti-F(ab')(2) antibody, where suppression of anti-F(ab')(2) antibody synthesis is accompanied by enhancement of the anti-Fc response; and (b) human secretory IgA + passive anti-serum IgA antibody, where suppression of antibody production against the alpha and L chains accompanies augmentation of the response to the secretory component. The mechanisms of the suppressive and enhancing effects are probably unrelated for the following reasons: (a) Enhancement of the response to certain determinants may be obtained without discernible suppression of the response to the homologous determinants; and (b) the F(ab')(2) fragments of passive antibody can mediate immune suppression but were not observed to enhance the response against the unrelated determinants of the same antigen molecule. Also, the timing for achieving maximum suppression or enhancement of antibody formation is not the same; enhancement was obtained only at a later time. Both the enhancement and suppressive effects were obtained with the purified gammaG fraction of antisera. This finding rules out an exclusive role of gammaM antibody in the enhancement phenomenon.

Animals↗
PubMed1986

On the mechanism of unidirectional killing in mixtures of two cytotoxic T lymphocytes. Unidirectional polarization of cytoplasmic organelles and the membrane-associated cytoskeleton in the effector cell.

In mixtures of two CTL of the type a anti-b and b anti-c, only the latter is lysed; i.e., killing is unidirectional. Here, we show that two profound types of changes occur in the effector CTL but not in the target CTL upon formation of couples between them. One is that the microtubule organizing center (and presumably the Golgi apparatus that is invariably colocalized with it) is reoriented inside the effector CTL to face the bound target CTL. This unidirectional reorientation, it is proposed, serves to direct putative cytotoxic secretory components derived from the Golgi apparatus of the effector cell to the site of cell-cell binding. The second unidirectional change is in the membrane-associated cytoskeleton of the effector CTL in the area of target cell binding. The cytoskeletal protein talin, but not any of four other such proteins assayed, is highly concentrated at the contacting membrane of the effector CTL, while it is uniformly distributed over the entire membrane of the bound target CTL. This localized, massive cytoskeletal reorganization may reflect a mechanism to protect the membrane of the effector CTL from the effects of putative cytotoxic components secreted by the effector cell into the intercellular space between it and the target cell.

Animals↗
PubMed1995

The rho-GAP encoded by BEM2 regulates cytoskeletal structure in budding yeast.

Microfilaments are required for polarized growth and morphogenesis in Saccharomyces cerevisiae. To accomplish this, actin cables and patches are redistributed during the cell cycle to direct secretory components to appropriate sites for cell growth. A major component of actin cables is tropomyosin I, encoded by TPM1, that determines or stabilizes these structures. Disruption of TPM1 is not lethal but results in the loss of actin cables and confers a partial defect in polarized secretion. Using a synthetic lethal screen, we have identified seven mutations residing in six genes whose products are required in the absence of Tpm1p. Each mutant exhibited a morphological defect, suggesting a functional link to the actin cytoskeleton. Complementation cloning of one mutation revealed that it lies in BEM2, which encodes a GTPase-activating protein for the RHO1 product. bem2 mutations also show synthetic lethality with rho1 and mutations in certain other cytoskeletal genes (ACT1, MYO1, MYO2, and SAC6) but not with mutations in several noncytoskeletal genes. These data therefore provide a genetic link between the GAP encoded by BEM2 and the functional organization of microfilaments. In addition, we show that bem2 mutations confer benomyl sensitivity and have abnormal microtubule arrays, suggesting that the BEM2 product may also be involved directly or indirectly in regulating microtubule function.

Actin Cytoskeleton↗
PubMed1987

Immunohistochemical characteristics of proliferative and metaplastic lesions in bronchial mucosa.

To elucidate the characteristics of metaplastic changes of bronchial mucosa, the distribution of four epithelial antigens and two subtypes of enolases was studied immunohistochemically. The authors classified the metaplastic changes into three types: basal cell hyperplasia, stratification, and squamous metaplasia. Secretory component (SC) was detected in all lesions with stratification and in three of ten lesions of squamous metaplasia. Epithelial membrane antigen (EMA) was localized not only on the luminal surfaces but also among the stratified layers of metaplastic epithelium. No carcinoembryonic antigen (CEA) was detectable in normal epithelium, whereas almost all metaplastic lesions had both nonspecific cross-reacting antigen (NCA) and CEA immunoreactivity. In normal mucosa, basal cells were strongly positive for alpha-enolase but negative for gamma-enolase, and columnar cells expressed both enolases. In areas of metaplasia, alpha-enolase was present throughout the layer, but gamma-enolase was absent. These immunohistochemical findings suggest that metaplastic squamous epithelial cells have glandular differentiation and that several biochemical and metabolic aberrations occur during the process of metaplasia.

Antigens, Surface↗
PubMed1990

Clinicopathologic and immunohistochemical characteristics of bronchial gland cell type adenocarcinoma of the lung.

Twenty-three cases of bronchial gland cell (BGC) type lung adenocarcinoma were examined clinicopathologically and immunohistochemically. BGC type adenocarcinoma was defined as adenocarcinoma showing histologic and cytologic differentiation toward the bronchial gland. This type of adenocarcinoma occurred more frequently in younger patients (mean age, 50.5 years) than in patients with other types of adenocarcinoma (mean age, 60.1 years). It had a tendency to arise from relatively large bronchi and show endobronchial growth. However, there was no difference in disease stage based on tumor, nodal involvement, metastases (TNM) factors and outcome between BGC type adenocarcinoma and peripheral type adenocarcinoma. Immunohistochemically, 50%, 68%, and 64% of BGC type adenocarcinomas were positive for carcinoembryonic antigen, surfactant apoprotein, and secretory component, respectively. Peripheral type adenocarcinomas showed similar rates of immunohistochemical stainability of these antigens. The positive reaction of BGC type adenocarcinomas with anti-surfactant apoprotein antibody may indicate maintenance of traces of differentiation toward peripheral airway epithelium. Lactoferrin is characteristically detected in BGC type adenocarcinomas, although the positive rate was not very high.

Adenocarcinoma, Bronchiolo-Alveolar↗
PubMed1990

Large cell carcinoma of the lung. Prognostic implications of histopathologic and immunohistochemical subtyping.

Fifty-four patients with large cell carcinoma of the lung were treated surgically, and the prognostic factors were examined histologically and immunohistochemically. Based on evidence of intercellular cohesion, as seen in the histologic results, the patients were placed into two subtypes, compact growth type and louse structure type. The survival rates were 46% and 28% at five years, respectively (P less than 0.05). Immunohistochemically, keratin, epithelial membrane antigen (EMA), secretory component, lactoferrin, and carcinoembryonic antigen (CEA), as histologic markers of epithelial differentiation, were detectable in large cell carcinoma of both types and more frequently in the compact growth type than in the loose structure type. The difference was significant in case of detection of keratin, EMA, and CEA (P less than 0.05). These observations suggest that a large cell carcinoma may differentiate into an adenocarcinoma or squamous cell carcinoma. The presence of intercellular cohesion and use of these markers reflect prognosis of the disease.

Adult↗
PubMed1995

Nasopharyngeal antibodies to pneumococcal capsular polysaccharides in children with acute otitis media.

Antibodies to pneumococcal capsular polysaccharides were measured by EIA in acute- and convalescent-phase nasopharyngeal aspirates from 120 children with acute otitis media. Nasopharyngeal IgM- and IgG-class antibodies were rare, whereas IgA was detected more often, occurred independently from serum IgA, and correlated with the presence of the secretory component in pneumococcal antibody, indicating local production of IgA. Thirty-four percent of the children with pneumococci in middle ear fluid developed a nasopharyngeal IgA response to the polysaccharide pool of serotypes 6B, 14, 19F, and 23F compared with 7% of the children with pneumococci only in the nasopharynx or not found at all (P = .004). The responses were observed in children of all ages, the youngest 6 months of age. This supports the hypothesis that mucosal immunity to bacterial polysaccharides matures earlier than systemic immunity.

Acute Disease↗
PubMed1998

In vivo stimulation of polymeric Ig receptor transcytosis by circulating polymeric IgA in rat liver.

Binding of human polymeric IgA ligand to its epithelial cell polymeric Ig receptor, pIgR, has been shown to stimulate pIgR apical transcytosis in an in vitro system, based on polarized confluent MDCK cells expressing rabbit pIgR. The present study aimed at testing whether such a stimulation also occurs in vivo. Transcytosis of pIgR was monitored by rat liver output of total secretory component (SC) into bile, measured by radial immunodiffusion as the sum of free SC and pIgA-bound SC. Whereas in the perfused rat liver system addition of pIgA to the perfusate showed no effect, i.v. injection of human and rat pIgA, but not of monomeric IgA nor PBS, in living rats significantly increased total bile SC output for more than 1 h. Furthermore, depletion of the normal pIgA level circulating in the liver before injecting more pIgA was not required to show the stimulation. Our data thus strongly suggest that stimulation of liver pIgR transcytosis by pIgA ligand binding is physiologically relevant, helping to quickly adjust pIgA transport into bile to increase circulating pIgA levels, without need for increased SC/pIgR synthesis.

Animals↗
PubMed2002

A novel lipid raft-associated glycoprotein, TEC-21, activates rat basophilic leukemia cells independently of the type 1 Fc epsilon receptor.

Recent data suggest that initiation of signal transduction via type 1 Fc epsilon receptor (Fc epsilon RI) and other immunoreceptors is spatially constrained to lipid rafts. In order to better understand the complexity and function of these structures, we prepared mAb against lipid rafts from the rat basophilic leukemia cell line, RBL-2H3, which is extensively used for analysis of Fc epsilon RI-mediated activation. One of the antibodies was found to recognize a novel glycosylphosphatidylinositol-anchored plasma membrane glycoprotein of 250 amino acids, designated TEC-21, containing a cysteine-rich domain homologous to those found in the urokinase plasminogen activator receptor/Ly-6/snake neurotoxin family. TEC-21 is abundant on the surface of RBL-2H3 cells (>10 (6) molecules/cell), but is absent in numerous rat tissues except for testes. Aggregation of TEC-21 on RBL-2H3 cells induced a rapid increase in tyrosine phosphorylation of several substrates including Syk kinase and LAT adaptor, calcium flux, and release of secretory components. Similar but more profound activation events were observed in cells activated via Fc epsilon RI. However, aggregation of TEC-21 did not induce changes in density of IgE-Fc epsilon RI complexes, tyrosine phosphorylation of Fc epsilon RI beta and gamma subunits, and co-aggregation of Lyn kinase. TEC-21-induced activation events were also observed in Fc epsilon RI(-) mutants of RBL-2H3 cells. Thus, TEC-21 is a novel lipid raft component of RBL-2H3 cells whose aggregation induces activation independently of Fc epsilon RI.

Amino Acid Sequence↗
PubMed2006

Production of reactive oxygen species in Arabidopsis thaliana cell suspension cultures in response to an elicitor from Fusarium oxysporum: implications for basal resistance.

The present understanding of ROS generation in the defence response of Arabidopsis thaliana is reviewed. Evidence suggests that the apoplastic oxidative burst generated during basal resistance is peroxidase-dependent. The ROS generated during this basal resistance may serve to activate NADPH oxidase during the R-gene-mediated hypersensitive response. The processes involved in the production of reactive oxygen species in A. thaliana cell suspension cultures in response to an elicitor from Fusarium oxysporum are investigated in the present work. This system appears analogous to the production of ROS during the basal resistance response in French bean, which is peroxidase-dependent. A panel of modulators effective in other pathogen elicitor and plant cell systems has been used to investigate the Arabidopsis signalling pathways and the plant cell responses involved. Thus as in other systems, an early calcium influx into the cytosolic compartment, a rapid efflux of K(+) and Cl(-), and extracellular alkalinization of elicited cell cultures has been found. However the alkalinization is not sufficient to stimulate the apoplastic oxidative burst by itself, unlike in French bean, although vectorial ion fluxes are needed. A secretory component which is sensitive to monensin and N-ethylmaleimide and insensitive to brefeldin A may also be necessary for the release and provision of substrates for peroxidase-dependent generation of H(2)O(2).

Arabidopsis↗
PubMed1984

Genes encoding alpha-heavy chains of rabbit IgA: characterization of cDNA encoding IgA-g subclass alpha-chains.

cDNA molecules encoding rabbit IgA alpha-heavy chains have been synthesized and six of these have been characterized. The complete nucleotide sequence of one cDNA, p 19 (942bp), showed that it encoded all but the N-terminal 57 amino acid residues of the constant region of alpha-chains. The cDNA molecules were subcloned into the expression vector pUC8 and E. coli were transformed. Radioimmunoassay of the molecules synthesized by these clones showed that all six cDNA molecules encoded alpha-chains of the IgA-g subclass. Comparison of the amino acids encoded by the alpha-cDNA with the amino acid sequence of mouse and human alpha-chains showed that although all of the intradomain disulfide bonds appear to be conserved, some positions, probably involved in interchain disulfide bonds, are not conserved. We propose that secretory component is covalently bound to cysteine 299 and/or cysteine 301 of the CH2 domain of mouse and human alpha-chains. The results from Southern blot analysis of genomic DNA with 32P-cDNA suggests that the rabbit genome has multiple C alpha genes.

Animals↗
PubMed1991

Human endometrial peptides: a review of their potential role in implantation and placentation.

This paper reviews human endometrial peptide synthesis and discusses the biological function of these peptides in relation to implantation and placentation. Despite the substantial literature on quantitative and qualitative peptide synthesis by the endometrium, it has not been possible to define the function of most of these substances. Various aspects of endometrial morphology, especially the endometrial leukocytes, are discussed in an attempt to relate cellular structure and function. A number of serum proteins are produced by the endometrial glandular epithelium and may play a role in early embryo development. Extracellular matrix proteins produced by stromal cells are important for endometrial structure and integrity but also provide a site for trophoblast attachment. Several hormones and binding proteins are also produced by stromal cells and probably influence endometrial metabolism. Complement factors and secretory component may have a role in maintaining a sterile intrauterine environment. Many other endometrial proteins have been less well characterized and their role in endometrial physiology at present remains uncertain. Perhaps the most exciting advance has been the realization that a number of peptide regulatory factors (cytokines and growth factors) are not only produced by the endometrium but play an integral part in the mediation of oestrogen-induced growth and differentiation of the endometrium and with the local metabolic and physiological processes.

Animals↗
PubMed1995

Polymeric immunoglobin (Ig) receptor production and IgA transcytosis in polarized primary cultures of mature rat uterine epithelial cells.

These studies were conducted to more fully understand the role of uterine epithelial cells (UEC) in immunoglobin (Ig)A movement from tissue into secretions in the female reproductive tract. Indirect immunofluorescence and image analysis showed that the polymeric Ig receptor (pIgR), which is responsible for transporting polymeric IgA (pIgA) across epithelial cells, was expressed in uterine tissues from rats throughout the estrous cycle. UEC pIgR levels were higher at estrus than at either proestrus or diestrus. When UEC were isolated from the uteri of adult rats and grown on cell culture inserts, cells grew to confluence, formed tight junctions, and released secretory component (SC), the external domain of the pIgR, into the apical medium. Irrespective of whether UEC were isolated from the uteri of rats at the diestrous, proestrous, or estrous stages of the reproductive cycle, cells produced SC, indicating that they are capable of IgA transport. 125I-IgA was preferentially transcytosed from the basolateral to the apical surface, demonstrating that dimeric IgA (dIgA) could be transported by UEC in culture. In contrast, the fluid phase marker [3H]inulin moved at a comparable rate in both directions across the cell monolayer. 125I-IgA transport through UEC was saturable and specific for pIgA in that unlabeled pIgA, but not IgG, inhibited 125I-dIgA transcytosis from the basolateral to the apical surface. Immunoprecipitation of 125I-IgA in the apical chamber with rabbit anti-SC antibody indicated that after transepithelial movement, IgA was bound to SC. Northern blot analysis of RNA extracted from UEC demonstrated that cells continued to synthesize pIgR mRNA in culture. Our results suggest that in the uterus, epithelial cells play a key regulatory role in the control of IgA transcytosis from tissue into secretions.

Animals↗