L-Tryptophan prevents Escherichia coli biofilm formation and triggers biofilm degradation

The effect of deletion of trp operon and tna operon on the Escherichia coli biofilm formation was investigated in order to elucidate the role of L-tryptophan metabolism in biofilm formation. trp operon deletion mutants ΔtrpC, ΔtrpD and ΔtrpE deficient in L-tryptophan biosynthesis showed higher biofilm formation. In addition, ΔtnaC with increased L-tryptophan degradation activity showed higher biofilm formation. On the contrary, ΔtnaA deletion mutant which lost L-tryptophan degradation activity showed low biofilm formation. From these results, it was suggested that decrease of intracellular L-tryptophan level induced biofilm formation and increase of L-tryptophan repressed biofilm formation. So the effect of the addition of L-tryptophan to the medium on the E. coli biofilm formation was investigated. L-Tryptophan addition at starting culture decreased biofilm formation and furthermore L-tryptophan addition after 16 h culture induced the degradation of preformed biofilm. From the above results, it was suggested that maintenance of high intracellular L-tryptophan concentration prevents E. coli biofilm formation and elevation of intracellular L-tryptophan concentration triggers degradation of matured biofilm.     

Mixed-Species Biofilm Formation by Lactic Acid Bacteria and Rice Wine Yeasts

We found that species combinations such as Lactobacillus casei subsp. rhamnosus IFO3831 and Saccharomyces cerevisiae Kyokai-10 can form a mixed-species biofilm in coculture. Moreover, the Kyokai-10 yeast strain can form a biofilm in monoculture in the presence of conditioned medium (CM) from L. casei IFO3831. The active substance(s) in bacterial CM is heat sensitive and has a molecular mass of between 3 and 5 kDa. In biofilms from cocultures or CM monocultures, yeast cells had a distinct morphology, with many hill-like protrusions on the cell surface.     

Characterization of a Dopamine-Releasing Action of 6R-l-erythro-Tetrahydrobiopterin: Comparison with a 6S-Form

Abstract: 6R-l -erythro-Tetrahydrobiopterin (6R-BH₄) is a cofactor for aromatic l -amino acid hydroxylases and nitric oxide synthase. Recently, we have reported that independently of its cofactor activities, 6R-BH₄ acts from the outside of neurons in the brain to enhance the release of monoamine neurotransmitters such as dopamine. To characterize the pharmacological properties of the action, we examined the effects of 6S-BH₄, a diastereoisomer of 6R-BH₄, on dopamine release in the rat striatum by using brain microdialysis and compared its effects with those of 6R-BH₄. Perfusion of 6S-BH₄ or 6R-BH₄ through the dialysis probe increased extracellular dopamine levels (an index of in vivo dopamine release) concentration dependently; the maximal increase by 6S-BH₄, was one-sixth of that by 6R-BH₄. 6S-BH₄ increased extracellular DOPA levels in the presence of NSD 1015, an inhibitor of aromatic l -amino acid decarboxylase (an index of in vivo tyrosine hydroxylase activity), to an extent similar to the increase induced by 6R-BH₄. The increase in the DOPA levels induced by either of the pteridines was abolished after pretreatment of rats with α-methyl-p-tyrosine (an inhibitor of tyrosine hydroxylase). Under the same conditions, the 6S-BH₄-induced dopamine release was abolished, but most of the 6R-BH₄-induced increase persisted. Coadministration of 6S-BH₄ with 6R-BH₄ inhibited the increase in dopamine release induced by 6R-BH₄ alone. These results show that 6R-BH₄ stimulates dopamine release by acting at the specific recognition site on the neuronal membrane, and that 6S-BH₄ acts as an antagonist of 6R-BH₄ at this site, although it has cofactor activities.     

Lipopolysaccharide inhibits activation of latent transforming growth factor-β in bovine endothelial cells

The activation of latent transforming growth factor-β (TGF-β) by vascular endothelial cells (ECs) is regulated by cellular plasminogen activator (PA)/plasmin, transglutaminase (TGase), and latent TGF-β levels. Because lipopolysaccharide (LPS) has been reported to reduce EC surface plasmin levels by increasing the production of the inhibitor of PA, PA inhibitor-1 (PAI-1), we have tested whether LPS might suppress latent TGF-β activation in ECs using two different systems, namely, bovine aortic ECs (BAECs) cocultured with smooth muscle cells (SMCs) and BAECs treated with retinol. BAECs were either cocultured with SMCs after treatment with 15 ng/ml LPS or were treated with 2 μM retinol and/or 10 ng/ml LPS, and the expression of PA, surface plasmin, TGase, and the amounts of active and latent TGF-β secreted into the culture modium were measured. The downregulation of surface PA/plasmin levels with LPS was accompanied by a profound decline of both TGase and latent TGF-β expression as well as the suppression of surface activation of latent TGF-β. The effect was dependent on the concentration of LPS and on treatment time. The formation of TGF-β did not occur in cells maintained in LPS-contaminated culture medium. © 1995 Wiley-Liss, Inc.     

Effects of Citrus unshiu powder on the cytokine balance in peripheral blood mononuclear cells of patients with seasonal allergic rhinitis to pollen

We evaluated the effects of a 50% methanol extract of Citrus unshiu powder (MEC) on cytokines in peripheral blood mononuclear cells (PBMCs) obtained from patients with seasonal allergic rhinitis to cedar pollen. The levels of cytokines, such as TNF-alpha, IFN-gamma, IL-2, IL-4, IL-5, IL-10, IL-12 (p70), IL-13, and GM-CSF, produced by pollen-stimulated PBMC were measured. We found that MEC suppressed pollen-induced TNF-alpha release and increased IFN-gamma release from PBMCs. The results suggest that Citrus unshiu powder has an immunomodulatory effect in vitro and that its use could improve seasonal allergic rhinitis symptoms.     

Differential spontaneous killing of human and murine tumour cell lines by leucocyte subpopulations from carp peripheral blood leucocytes

Cell populations from carp (Cyprinus carpio L.) peripheral blood leucocytes (PBLs) were examined for nonspecific cytotoxicities. By using monoclonal antibodies (MAbs) against carp thrombocytes (TCL-HB8) and both neutrophils and monocytes (TCL-BE8), PBLs with a density of 1.08 g ml-1 were separated into three fractions: thrombocytes, a mixture of neutrophils and monocytes, and other cells (mainly lymphocytes), and the separated cells were tested for cytotoxic activities against mammalian tumour cell lines (K562, HeLa, P815 and Yac-1 cell). Consequently, the mixture of neutrophils and monocytes exhibited cytolysis against these target cells, whereas the lymphocyte-rich and thrombocyte fractions did not show any cytolysis. To isolate only neutrophils, which do not contain monocytes, the MAb (TCL-BE8) positive cells from PBLs with a density of 1.08-1.09 g ml-1 were separated. Pure isolated neutrophils showed cytotoxic activities against K562 cells, but not P815 cells. Furthermore, analysis of the cytolytic mechanisms indicated that killing of these cells depended on H2O2 or HOCl. These results suggest that both neutrophils and monocytes are effectors for nonspecific cytotoxicity in carp PBLs, and neutrophils may be distinct from monocytes in their reactivity in cytolysis, including target cell selectivity and/or target cell sensitivity, and the cytolytic pathway. In carp, cytotoxicity of target cells can be mediated by several populations of their leucocytes which have cytotoxic capacities with various recognition and cytolytic mechanisms.     

Fourteen morphotypes of Entodinium ovumrajae (Ophryoscolecidae, Entodiniomorphida) found in the Dromedary camel of Egypt

During a survey of the ciliate protozoal composition of the stomach contents of nine dromedary camels of Egypt, fourteen morphotypes of Entodinium ovumrajae, which has been considered as a species peculiar to camels, were found in six camels. Except for five morphotypes including one originally described as an independent species and its forms, these were newly detected. These morphotypes, divided into three groups, can be identified mainly by the morphology of their ectoplasmic processes. Each camel had on average, about five morphotypes of this species.     

IL-27-producing CD14(+) cells infiltrate inflamed joints of rheumatoid arthritis and regulate inflammation and chemotactic migration

Interleukin (IL)-27, a heterodimeric cytokine, has been reported to be involved in the pathogenesis of autoimmune diseases through mediating differentiation of Th1 or Th17 cells and immune cell activity or survival. However, the origin and effects of IL-27 in joints of rheumatoid arthritis (RA) remain unclear. In this study, we investigated the distribution and anti-inflammatory roles of IL-27 in RA synovium. The IL-27 levels in plasma of RA patients, osteoarthritis (OA) patients, or healthy volunteers (n=15 per group) were equivalent and were at most 1 ng/ml, but the IL-27 level in synovial fluid of RA patients (n=15, mean 0.13 ng/ml; range 0.017-0.37 ng/ml) was significantly higher than that in synovial fluid of OA patients (n=15, mean 0.003 ng/ml; range 0-0.033 ng/ml) and potentially lower than in plasma. We analyzed the protein level of IL-27 produced by RA fibroblast-like synoviocytes (FLSs) or mononuclear cells (MNCs) from RA or OA synovial fluid or peripheral blood and showed that IL-27 in RA joints was derived from MNCs but not from FLSs. We also found by flow cytometry that IL-27-producing MNCs were CD14(+), and that these CD14(+)IL-27(+) cells were clearly detected in RA synovium but rarely in OA synovium by immunohistochemistry. Furthermore, we demonstrated that a relatively physiological concentration of IL-27 below 10 ng/ml suppressed the production of IL-6 and CCL20 from RA FLSs induced by proinflammatory cytokines through the IL-27/IL-27R axis. In the synovial fluid of RA, the IL-27 level interestingly had positive correlation with the IFN-γ level (r=0.56, p=0.03), but weak negative correlation with the IL-17A level (r=-0.30, p=0.27), implying that IL-27 in inflammatory joints of RA induces Th1 differentiation and suppresses the development or the migration of Th17 cells. These findings indicate that circulating IL-27-producing CD14(+) cells significantly infiltrate into inflamed regions such as RA synovium and have anti-inflammatory effects in several ways: both directly through the reduction of IL-6 production, and possibly through the induction of Th1 development and the suppression of Th17 development; and indirectly by regulation of recruitment of CCR6(+) cells, such as Th17 cells, through the suppression of CCL20 production. Our results suggest that such a serial negative feedback system could be applied to RA therapy.     

Condensation Reaction Occurring during Plastein Formation by α-Chymotrypsin

An investigation was conducted on myosin and actin-activated heavy meromyosin (HMM) ATPase activities in normal porcine muscle stored for varying periods of time after death. Studies were also made on temperature dependent myosin ATPase, initial burst of ATPase and actin-activated HMM ATPase in normal and in pale, soft and exudative (PSE) porcine muscle. The maximum velocity of acto-HMM ATPase of normal muscle decreased considerably with postmortem time, while the apparent dissociation constant decreased slightly. The maximum velocity of acto-HMM ATPase of postmortem normal muscle was approximately two-times larger than that of the corresponding PSE muscle. However, almost no difference was found in the apparent dissociation constant. The size of the initial burst of phosphate-liberation of myosin prepared from normal muscle was approximately 1.2 mol/mol of myosin and from PSE muscle 0. It is assumed that the lack of contractility of PSE muscle was brought about by two basic myosin malfunctions: one, the irreversible binding of myosin to actin filament and the other, the functional damage of myosin ATPase, responsible for the formation of phosphorylated complex, even when dissociable.