ABSTRACT
We have carried out scanning tunneling microscopy (STM) observations of unreconstructed regions on quenched Si(1 1 1) surfaces at 380 degrees C at a scanning speed of 1.7 s per frame. In the regions, it is found that single faulted-halves of the dimer-adatom-stacking-fault (DAS) structure are formed isolatedly or at the edges of the surrounding DAS domains sharing one corner hole. In such "living" regions, we have succeeded to observe sudden structural changes of the faulted-halves during line scans in single frames of STM images.
ABSTRACT
1. During the destruction of articular cartilage, fibrinolytic enzymes and matrix metalloproteinases (MMP) may contribute to the related pathology. The activities, antigens and messenger RNA (mRNA) levels of urokinase-type plasminogen activator (uPA) and plasminogen activator inhibitor-1 (PAI-1) in articular cartilage were measured in patients with no history of joint diseases (control), those with osteoarthritis (OA) classified into osteophyte-formed site (OS) and weight-bearing site (WS), and in patients with rheumatoid arthritis (RA). 2. The uPA content was higher in WS and RA compared to normal. The PAI-1 content was higher in OS and RA compared to normal. Weight-bearing site patients expressed a high uPA mRNA level but a low PAI-1 mRNA level. Osteophyte-formed site patients expressed a low uPA mRNA level but a high PAI-1 mRNA level. 3. The levels of the MMP and mRNA of tissue inhibitors of metalloproteinases (TIMP) were measured in WS, OS, and RA. In WS, the levels of MMP were high and levels of TIMP mRNA expression low. In OS, the levels of TIMP were high and levels of MMP mRNA were low. In RA, the levels of MMP and TIMP mRNA were high. 4. These findings suggest that regulation of fibrinolysis may play an important role in the matrix of articular cartilage with arthropathy.
Subject(s)
Cartilage, Articular/enzymology , Metalloendopeptidases/metabolism , Serine Endopeptidases/metabolism , Aged , Antigens/metabolism , Arthritis, Rheumatoid/enzymology , Arthritis, Rheumatoid/etiology , Female , Glycoproteins/immunology , Glycoproteins/metabolism , Humans , Male , Middle Aged , Osteoarthritis/enzymology , Osteoarthritis/etiology , Plasminogen Activator Inhibitor 1/immunology , Plasminogen Activator Inhibitor 1/metabolism , RNA, Messenger/metabolism , Tissue Inhibitor of Metalloproteinases , Urokinase-Type Plasminogen Activator/immunology , Urokinase-Type Plasminogen Activator/metabolismABSTRACT
We investigated the effect of cyclic AMP (cAMP) on the pericellular fibrinolytic system in NY cells. Dibutyryl cAMP (dbcAMP) or forskolin increased the level of urokinase-type plasminogen activator (u-PA) mRNA and enhanced the secretion of u-PA antigen into the conditioned medium. These agents also increased u-PA antigen on the cell surface. PA inhibitor-1 (PAI-1) antigen was inhibited by dbcAMP or forskolin. Butyrate had no effect on the production and secretion of u-PA and PAI-1. A binding assay of 125I-DFP-u-PA to NY cells revealed a single class of binding sites with a Kd of 3.85 nM and Bmax of 0.89.10(5) binding sites/cell. The Bmax was increased by dbcAMP (1 mM or 10 mM), forskolin (2 microM or 20 microM) of 1.0-, 1.4-, 1.2- and 1.8-fold, respectively. However, the Kd value was not changed. Furthermore, the level of mRNA for the u-PA receptor (u-PAR) was increased by these agents 1.2-, 1.7-, 1.8- and 2.5-fold, respectively. However, butyrate did not alter either the Bmax or the u-PAR mRNA level. These results indicated that the pericellular fibrinolytic activity induced by u-PA/u-PAR is modulated by cAMP in osteoblast-like cells.
Subject(s)
Cyclic AMP/pharmacology , Plasminogen Activator Inhibitor 1/biosynthesis , Receptors, Cell Surface/drug effects , Urokinase-Type Plasminogen Activator/biosynthesis , Bucladesine/pharmacology , Butyrates/pharmacology , Butyric Acid , Cell Line/drug effects , Colforsin/pharmacology , Fibrinolysis/drug effects , Humans , Osteoblasts , Plasminogen Activator Inhibitor 1/genetics , RNA, Messenger/analysis , Receptors, Cell Surface/genetics , Receptors, Urokinase Plasminogen ActivatorABSTRACT
The refractive index of air-hydrate crystals found in a deep Antarctic ice sheet was measured for the first time, as far as we know, using a Mach-Zehnder interferometer. A small difference between the refractive indices of the air-hydrate crystals and the matrix ice crystal was measured by the fringe-shift method. It was found that the refractive indices of all air-hydrate crystals were larger than those of ice, and the average difference was 5.3 × 10(-3), even considering the refractive-index anisotropy of ice crystals. Because the refractive indices depend on the occupancy ratio of cagelike cavities by air molecules, we compared the experimental results with the calculated values using the Onsager cavity model. We determined that the present method is useful for estimation of the cavity occupancy ratio of air-hydrate crystals and also of the amount of air molecules in polar ice cores.
ABSTRACT
This study investigated the effect of bone resorbing factors on the pericellular fibrinolytic system of osteosarcoma NY cells. Parathyroid hormone (PTH), prostaglandin E2, (PGE2) or tumor necrosis factor alpha (TNF-alpha) enhanced the secretion of urokinase-type plasminogen activator (u-PA) antigen and suppressed the secretion of plasminogen activator inhibitor-1 (PAI-1) antigen to the conditioned medium. The former two factors also increased u-PA antigen in the cell surface. Transforming growth factor beta (TGF-beta) enhanced u-PA antigen, but its activity was suppressed due to the increased secretion of PAI-1. The binding assay of [125I]DFP-u-PA to NY cells revealed the presence of a single class of binding sites with a Kd of 5.51 nM and Bmax of 0.92 x 10(5) binding sites/cell. PTH or PGE2 increased Bmax 1.4-fold and enhanced the u-PA receptor (u-PAR) mRNA level 1.4-fold or 2.4-fold, respectively. However, TGF-beta did not alter either the Kd or u-PAR mRNA level. Thus, pericellular fibrinolytic activity by u-PA/u-PAR and PAI-1 is modulated by bone resorbing factors.
