Uptake and degradation of a polypeptide antigen by stimulated and unstimulated macrophages from responder and non-responder mice.
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A novel member of the EGF-TM7 family, mEMR4, was identified and characterized. The full-length mouse EMR4 cDNA encodes a predicted 689-amino acid protein containing two epidermal growth factor (EGF)-like modules, a mucin-like spacer domain, and a seven-transmembrane domain with a cytoplasmic tail. Genetic mapping established that mEMR4 is localized in the distal region of mouse chromosome 17 in close proximity to another EGF-TM7 gene, F4/80 (Emr1). Similar to F4/80, mEMR4 is predominantly expressed on resident macrophages. However, a much lower expression level was also detected in thioglycollate-elicited peritoneal neutrophils and bone marrow-derived dendritic cells. The expression of mEMR4 is up-regulated following macrophage activation in Biogel and thioglycollate-elicited peritoneal macrophages. Similarly, mEMR4 is over-expressed in TNF-alpha-treated resident peritoneal macrophages, whereas interleukin-4 and -10 dramatically reduce the expression. mEMR4 was found to undergo proteolytic processing within the extracellular stalk region resulting in two protein subunits associated noncovalently as a heterodimer. The proteolytic cleavage site was identified by N-terminal amino acid sequencing and located at the conserved GPCR (G protein-coupled receptor) proteolytic site in the extracellular region. Using multivalent biotinylated mEMR4-mFc fusion proteins as a probe, a putative cell surface ligand was identified on a B lymphoma cell line, A20, in a cell-binding assay. The mEMR4-ligand interaction is Ca2+-independent and is mediated predominantly by the second EGF-like module. mEMR4 is the first EGF-TM7 receptor known to mediate the cellular interaction between myeloid cells and B cells.
Extracellular oxidase of the white rot fungus Panus tigrinus (earlier reported as laccase) contains copper but has no absorption spectrum typical of 'blue' oxidases. Thioglycolate and sodium azide inhibit the activity of this enzyme at concentrations 2.5-3 orders lower than those needed for fungal laccases. The oxidase of P. tigrinus oxidizes syringaldazine, coniferyl alcohol, ABTS, syringic acid, diaminobenzidine, guaiacol, catechol and vanillylacetone with different efficiencies. Oxygen consumption and no hydrogen peroxide formation were detected during substrate oxidation by P. tigrinus oxidase. It is proposed that P. tigrinus oxidase is a new ligninolytic enzyme.
A total of 176 Gram-positive, catalase positive cocci strains, isolated from sheep were studied by different routine tests for the differentiation of staphylococci and micrococci, comparing their validity and usefulness. By glucose fermentation and growth in the anaerobic portion of thioglycolate 85 and 73.6% respectively of coagulase negative staphylococci were misclassified as Micrococcus spp. Susceptibility to lysostaphin was an adequate test for the differentiation of the strains. Atypical results in the production of acid from glycerol/erythromycin were obtained in 11.8% of the coagulase negative strains and 16.7% of micrococci. The combined use of the selective media furazolidone agar and Schleifer and Krämer medium resulted in a fast and useful separation of ovine staphylococci and micrococci. The bacteriolytic activity misclassified 32.2% of the coagulase negative strains.
Zonular fibers contain large quantities of disulfide-groups which histochemically can be demonstrated after thiosulfation or reduction with sodium thioglycollate. Zonular fibers share these staining behaviours with oxytalan fibers and elastic fiber microfibrils. Smaller amounts of disulfide-groups can be demonstrated when visualized by means of the thioglycollate/ferric-ferricyanide method. Diffusion of acidic staining solutions seems to be limited in Descemet's membrane and in the lens capsule: only surfaces of these membranes become reactive after thiosulfation. It is assumed that the distribution of disulfide-groups in Descemet's membrane and in the lens capsule shows the distribution of type IV collagen.
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Nine commercial teat dip formulations containing 1.94% linear dodecylbenzene sulfonic acid, or 1% available iodine from nonylphenoxypoly (ethyleneoxy) ethanol-iodine complex, or .5% chlorhexidine acetate were tested for contamination with aerobic and anaerobic bacteria and their in vitro germicidal activity against Staphylococcus aureus, Streptococcus agalactiae, Escherichia coli, and Nocardia asteroides. All products were free of bacteria when neutralized samples were tested on blood agar or liquid thioglycollate media. To test for in vitro efficacy, each teat dip preparation was mixed with a suspension of one of the pathogenic test organisms containing 10(8) bacteria/ml (final concentration) for .5 to 15 min. Viable bacteria were evaluated by direct plating of neutralized aliquots and by filtration techniques. All products were effective against E. coli, Staph. aureus, and Strep. agalactiae. With N. asteroides, the direct plating method gave equivocal results. The filtration experiments indicated that all teat dips containing dodecylbenzene sulfonic acid and nonylphenoxypoly (ethyleneoxy) ethanol-iodine complex were effective against all four pathogens. Three of the teat dips containing chlorhexidine acetate were ineffective against N. asteroides. The fourth teat dip, containing chlorhexidine acetate and an emollient, was partially effective.
Components of the extracellular matrix (ECM) can regulate leukocyte activation and function at inflammatory sites. Low molecular weight fragments of the ECM glycosaminoglycan hyaluronan (LMW-HA) that accumulate in inflammation, but not the ubiquitous high molecular weight form of HA (HMW-HA), have been shown to induce cytokine and/or chemokine production by alveolar and bone-marrow derived macrophages. To determine the cellular requirements for responsiveness to HA, we compared the effects of HMW-HA and LMW-HA on resident and thioglycollate-elicited murine peritoneal macrophages. We demonstrate that treatment of elicited macrophages with LMW-HA, but not with HMW-HA, stimulated production of the chemokines RANTES and macrophage inflammatory protein-1alpha and -1beta. Further, we demonstrate that LMW-HA induced the production of biologically active IL-12, a proinflammatory cytokine not previously known to be regulated by cell-matrix interactions. The LMW-HA-induced production of IL-12 by elicited macrophages was inhibited by an anti-CD44 mAb that blocks HA binding. In contrast to elicited macrophages, freshly explanted resident peritoneal macrophages did not respond to LMW-HA. However, preculture in vitro before stimulation led to adhesion-dependent priming for LMW-HA-induced cytokine and chemokine production by resident macrophages. These results provide further evidence of the potential importance of CD44/LMW-HA interactions in regulating the immune response at sites of inflammation and demonstrate that the state of differentiation of macrophages may determine their sensitivities to matrix components.
A new species, Perkinsus mediterraneus, a protistan parasite of the European oyster Ostrea edulis (L.), farmed along the coast of the Balearic Islands, Mediterranean Sea, is described. Morphological examinations with light and transmission electron microscopy, DNA sequence-analysis and enlargement in Ray's fluid thioglycollate medium (RFTM) confirmed that this parasite belongs to the genus Perkinsus. Specific morphological and genetic characteristics indicated that it should be considered a new species in the genus. Sequencing of the small subunit ribosomal (ssu rRNA) gene confirmed that the parasite belongs to the genus Perkinsus, and sequences of the internal transcribed spacer (ITS) were distinct from any Perkinsus ITS sequences previously published and/or deposited in the GenBank. Phylogenetic analysis revealed that the ITS sequences of the new species formed a monophyletic group comprising a sister clade to the P. atlanticus/olseni group. In addition, morphological differences were observed between the new species and the other described Perkinsus spp.. After incubation in RFTM for 1 wk, the prezoosporangium had reached an extremely large size (97.4 +/- 1.99 microm) (mean +/- SE), and after 2 wk incubation had again almost doubled in size (167.1 +/- 8.09 microm). The discharge-tube length was one sixth the diameter of the zoosporangium, i.e. a ratio of 17.36:97.38, the lowest ratio observed for any Perkinsus species. At the ultrastructural level, zoosporangia and zoospores exhibited some differences compared to other Perkinsus species.
Transforming growth factor (TGF)-beta is a multifunctional cytokine, which in mammals exists in three isoforms (TGF-beta1, 2 and 3). It is synthesized by a variety of cells including macrophages, and exerts potent immunoregulatory effects such as the inhibition of Th1 development and the suppression or reversal of IFN-gamma-induced macrophage activation. In this study we analyzed the effect of IFN-gamma on the production of TGF-beta1 by thioglycolate-elicited mouse peritoneal macrophages under serum-free conditions. Untreated macrophages released TGF-beta1 in its latent form, which became detectable in a capture ELISA specific for active TGF-beta1 after acid activation of the culture supernatants. Treatment with IFN-gamma reduced the amount of latent TGF-beta1 in the culture supernatants in a dose-dependent fashion. The effect of IFN-gamma was confirmed by a newly developed Western blot system for the detection of mouse TGF-beta1 protein. IFN-gamma only weakly (16-24 %) reduced the levels TGF-beta1 mRNA at early and late time points of stimulation, and no evidence was obtained that IFN-gamma suppresses the secretion of latent TGF-beta1. Thus, inhibition of TGF-beta1 production by IFN-gamma is most likely due to decreased synthesis and/or stability of the TGF-beta1 protein, and might be important for the generation of fully activated macrophages and a Th1 response.
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OBJECTIVE: We investigated the effects of the energy signal on the reinforcing effects and palatability to fat in mice. METHODS: To examine the effects of postingestive energy signal, mice were injected with 400 micromol/kg body mass of mercaptoacetate, a beta-oxidation blocker or with saline (control group). Reinforcing effects and palatability response were examined with the conditioned place preference and one-bottle tests, respectively. RESULTS: In conditioned place preference tests, the mercaptoacetate group exhibited reinforcing effects when offered a 40% sucrose solution, which is not metabolized by the beta-oxidation pathway, but not when offered 100% corn oil. The control group exhibited reinforcing effects when offered the sucrose solution and when offered corn oil. In one-bottle tests, the control group exhibited palatability to corn oil, but the mercaptoacetate group did not. Consumption of sucrose solution was identical for both groups. CONCLUSIONS: These results suggest that postingestive energy signal influences the reinforcing effects and palatability of fat.
This study investigated the effects of the natural polyphenol mangiferin (MA) on superoxide anion (O(2)(-)) production, xanthine oxidase (XO) activity, vascular contractility, inducible nitric oxide synthase (iNOS) mRNA levels, tumour necrosis factor-alpha (TNF-alpha) mRNA levels, and tumour growth factor-beta (TGF-beta) mRNA levels. O(2)(-) was generated by the hypoxanthine-xanthine oxidase (HX-XO) and phenazine methosulphate (PMS)-NADH systems. XO activity was determined by measurement of uric acid production with xanthine as substrate. Vascular contraction experiments were performed with intact rat aortic rings. iNOS, TNF-alpha and TGF-beta gene expression in rat macrophages stimulated in vivo with 3% thioglycollate and in vitro with 100 ng/mL lipopolysaccharide and 10U/mL of interferon-gamma were evaluated semiquantitatively by the retrotranscriptase-polymerase chain reaction. MA at 10-100 microM, like the known O(2)(-) scavenger superoxide dismutase (1U/mL), scavenged O(2)(-) produced by the HX/XO and PMS-NADH systems. By contrast MA at 1-100 microM, unlike allopurinol (10 microM), was unable to inhibit XO activity. MA at 1-100 microM did not modify resting tone or the contractile responses elicited by 1 microM phenylephrine or 1 microM phorbol 12-myristate 13-acetate in rat aorta. MA at 1-100 microM, like dexamethasone (100 microM), decreased iNOS mRNA levels in activated macrophages. At 100 microM, MA also reduced TNF-alpha mRNA levels, but increased TGF-beta mRNA levels. These results thus indicate that MA is an O(2)(-) scavenger and that it inhibits expression of the iNOS and TNF-alpha genes, suggesting that it may be of potential value in the treatment of inflammatory and/or neurodegenerative disorders. In addition, the finding that MA enhances TGF-beta gene expression suggests that this polyphenol might also be of value in the prevention of cancer, autoimmune disorders, atherosclerosis and coronary heart disease.
Malondialdehyde-acetaldehyde (MAA) haptenated proteins have been described in disease processes related to prolonged oxidative stress (via malondialdehyde production), such as alcohol liver disease (ALD), non-alcoholic non-steatohepatitis (NASH) and atherosclerosis. Experimentally, high titer IgG1 antibody responses are seen after immunization without adjuvant; however, T cell proliferative responses and the role of scavenger receptors in this immunogenicity has not previously been described. In this study, T cell proliferative responses to the carrier protein, but not the MAA hapten itself, were identified in vitro. Moreover, these T proliferative responses were inhibited when MAA-hen egg lysozyme (HEL) was co-immunized with excess scavenger receptor ligand polyG (poly-guanylic acid), implicating the role of (a) scavenger receptor(s) in initiating the T helper cell response. Activated B cells were unable to process and present MAA-HEL preferentially to T cells, while thioglycollate-elicited (but not Con A-elicited) macrophages and dendritic cells (DC) did so with approximately 32-fold less MAA-HEL than native antigen necessary to initiate equal proliferative responses. While this preferential processing and presentation may be related to several factors, preferential binding of MAA haptenated proteins mediated by scavenger receptors may be one mechanism. IL-4 was absent from the supernatants of T proliferative assays despite a strong IgG1 response in vivo, although the TH2 cytokines IL-6 and IL-10 were expressed. Since the modification of proteins by the MAA have previously been shown to occur after ethanol consumption in vivo, the ability of MAA haptens to experimentally enhance immune responses, specifically humoral and T cell responses, may represent mechanisms by which autoimmune phenomena found in ALD occur.
Clostridium difficile produces a potent enterotoxin and cytotoxin, toxins A and B, respectively, which appear to be responsible for pseudomenbranous colitis and antibiotic-associated diarrhea. In the present study we explored the neutrophil migration evoked by toxin A in the peritoneal cavities and subcutaneous air pouches of rats and examined the role of macrophages and their inflammatory mediators in this process. Toxin A causes a significant dose-dependent neutrophil influx into the peritoneal cavity, with a maximal response at 0.1 microg/ml and at 4 h. The depletion of macrophages by peritoneal washing prevents the toxin A-induced neutrophil migration into the peritoneal cavity. In contrast, an increase in macrophages induced by peritoneal injection of thioglycolate amplifies this toxin effect on neutrophil migration. Furthermore, the injection of supernatants from toxin A-stimulated macrophages into the rat peritoneal cavity causes significant neutrophil migration. Pretreatment of rats with BWA4C, nordihydroguaiaretic acid, mepacrine, or dexamethasone inhibits the neutrophil migration evoked by toxin A in the peritoneal cavities. However, pretreatment with the cyclooxygenase inhibitor indomethacin or the platelet-activating factor antagonist BN52021 fails to alter toxin A-induced neutrophil migration. Toxin A was also injected into air pouches of normal rats or rats pretreated with anti-interleukin-1beta (anti-IL-1beta) or anti-tumor necrosis factor alpha (anti-TNF-alpha) antibodies. Anti-TNF-alpha or anti-IL-1beta antibodies significantly reduce the neutrophil migration induced by toxin A. These data suggest that neutrophil migration evoked by toxin A is in part dependent on macrophage-derived cytokines, such as TNF-alpha and IL-1beta, and leukotrienes. These mediators may help to explain the intense inflammatory colitis caused by C. dificile toxin A in an experimental animal model of this disease.