The lubricating activity of human synovial fluids

The lubricating abilities of human synovial fluids were measured using a rotating cartilage-on-glass apparatus. A total of 247 human fluids were lubricationtested. Of these, 20 of the 180 knee fluids from patients with degenerative/traumatic joint disease lubricated less well than normal bovine synovial fluid. The remainder of the fluids from the knee and other joints were equivalent to normal bovine synovial fluid in their lubricating properties. The concentrations of hyaluronic acid, protein, and sialic acid and the relative viscosity of 117 human fluid samples were determined, but no relationships between the gross composition and the lubricating abilities were apparent.     

环孢菌素A阻断人HL-60抗药性细胞于G1期而诱导敏感细胞凋亡

进一步研究了抗三尖杉酯碱的HL-60细胞(HR20)抗细胞凋亡的机制及该抗性和抗药性的关系。结果表明,环孢菌素A(CsA)20,10μg·ml^-1诱导HL-60细胞发生凋亡,而阻断HR20细胞于G₁期,就不能诱导细胞发生凋亡。低浓度的CsA明显增加柔红霉素在HR20细胞内的积聚,其逆转抗药性作用与阻断细胞周期运行无关。CsA10μg·ml^-1处理HR20细胞,可引起50kDa的蛋白质高度磷酸化。结果提示:环孢菌素A阻断抗三尖杉酯碱的HL-60细胞于G₁期,而诱导敏感的HL-60细胞发生凋亡,其阻断作用与抗药性无关。     

Prevalence of dental caries among children in a rural Tanzanian community

The age specific prevalences of mixed caries were determined in 346 children aged 1 to 15 years in a rural community in Morogoro Region, south-eastern Tanzania. In primary dentition 58.9% of children were caries free while dmf index averages 1.08. In permanent dentition 74.3% were caries free while DMF index averaged 0.43. Permanent dentition showed a constant increase in caries prevalence with age such that over half of 15 year old children had caries experience with a DMF index of 1.2. This relatively low prevalence of caries is associated with low consumption of refined sugars. Recommendations are made to support preventive dental health services and programmes in primary schools and maternal and child health clinics.     

Immune response profiling of primary monocytes and oral keratinocytes to different Tannerella forsythia strains and their cell surface mutants

The oral pathogen Tannerella forsythia possesses a unique surface (S‐) layer with a complex O‐glycan containing a bacterial sialic acid mimic in the form of either pseudaminic acid or legionaminic acid at its terminal position. We hypothesize that different T. forsythia strains employ these stereoisomeric sugar acids for interacting with the immune system and resident host tissues in the periodontium. Here, we show how T. forsythia strains ATCC 43037 and UB4 displaying pseudaminic acid and legionaminic acid, respectively, and selected cell surface mutants of these strains modulate the immune response in monocytes and human oral keratinocytes (HOK) using a multiplex immunoassay. When challenged with T. forsythia, monocytes secrete proinflammatory cytokines, chemokines and vascular endothelial growth factor (VEGF) with the release of interleukin‐1β (IL‐1β) and IL‐7 being differentially regulated by the two T. forsythia wild‐type strains. Truncation of the bacteria's O‐glycan leads to significant reduction of IL‐1β and regulates macrophage inflammatory protein‐1. HOK infected with T. forsythia produce IL‐1Ra, chemokines and VEGF. Although the two wild‐type strains elicit preferential immune responses for IL‐8, both truncation of the O‐glycan and deletion of the S‐layer result in significantly increased release of IL‐8, granulocyte‐macrophage colony‐stimulating factor and monocyte chemoattractant protein‐1. Through immunofluorescence and confocal laser scanning microscopy of infected HOK we additionally show that T. forsythia is highly invasive and tends to localize to the perinuclear region. This indicates, that the T. forsythia S‐layer and attached sugars, particularly pseudaminic acid in ATCC 43037, contribute to dampening the response of epithelial tissues to initial infection and hence play a pivotal role in orchestrating the bacterium's virulence.     

An endogenous glycosylphosphatidylinositol-specific phospholipase D releases basic fibroblast growth factor-heparan sulfate proteoglycan complexes from human bone marrow cultures

Basic fibroblast growth factor (bFGF) is a hematopoietic cytokine that stimulates stromal and stem cell growth. It binds to a glycosylphosphatidylinositol (GPI)-anchored heparan sulfate proteoglycan on human bone marrow (BM) stromal cells. The bFGF- proteoglycan complex is biologically active and is released by addition of exogenous phosphatidylinositol-specific phospholipase C. In this study, we show the presence of an endogenous GPI-specific phospholipase D (GPI-PLD) that releases the bFGF-binding heparan sulfate proteoglycan and the variant surface glycoprotein (a model GPI-anchored protein) from BM cultures. An involvement of proteases in this process is unlikely, because released proteoglycan contained the GPI anchor component, ethanol-amine, and protease inhibitors did not diminish the release. The mechanism of release is likely to involve a GPI-PLD and not a GPI-specific phospholipase C, because the release of variant surface glycoprotein did not reveal an epitope called the cross- reacting determinant that is exposed by phospholipase C-catalyzed GPI anchor cleavage. In addition, phosphatidic acid (which is specifically a product of GPI-PLD-catalyzed anchor cleavage) was generated during the spontaneous release of the GPI-anchored variant surface glycoprotein. We also detected GPI-PLD-specific enzyme activity and mRNA in BM cells. Therefore, we conclude that an endogenous GPI-PLD releases bFGF-heparan sulfate proteoglycan complexes from human BM cultures. This mechanism of GPI anchor cleavage could be relevant for mobilizing biologically active bFGF in BM. An endogenous GPI-PLD could also release other GPI-anchored proteins important for hematopoiesis and other physiologic processes.