3,629 research outputs found
Synthesis of extracellular matrix components by human ciliary muscle cells in culture
The production and spatial organization of connective tissue components in ciliary muscle cell cultures was studied with immunohistochemical and ultrastructural methods. Antibodies against collagen types IV and VI, fibronectin and laminin were used. Laminin stains as pericellular network surrounding individual muscle cells. Type IV collagen shows positive cytoplasmic staining and only small foci of extracellular immunofluorescence. Staining for type VI collagen and fibronectin is seen near the ends of the bipolar cells, while the lateral sides of the cells remain unstained. Electronmicroscopy shows that cultured ciliary muscle cells are surrounded by an incomplete basal lamina. In addition, bundles of 5-20 nm thick extracellular microfibrils are seen. The bundles are oriented parallel to the axis of the cells and are in close contact with the cell membrane in areas where membrane-bound dense bands are formed. Immunoelectronmicroscopy indicates that the bundles contain fibronectin and type VI collagen fibrils. While the fibronectin fibrils approach the cell membrane directly, type VI collagen fibrils are usually separated from the cell membrane by fine fibrillous material of different nature. Quality and spatial organization of the extracellular material in ciliary muscle cell cultures shows marked similarities with the extracellular matrix of ciliary muscle in situ
Diagnostic and prognostic value of bone biomarkers in progressive knee osteoarthritis: a 6-year follow-up study in middle-aged subjects
SummaryObjectiveTo determine the value of bone markers in early-stage progressive knee osteoarthritis (OA), a population-based cohort of middle-aged subjects with chronic knee complaints was followed over 6 years (two consecutive two 3-year periods).MethodsTibiofemoral (TF) and patellofemoral (PF) radiographs were graded in 128 subjects (mean age at baseline 45 ± 6.2 years) in 2002, 2005 and 2008. Bone formation was assessed by the serum concentration of procollagen type I amino-terminal propeptide (sPINP); bone resorption by the level of the C-terminal cross-linked telopeptides of type I collagen (sCTx-I); and bone mineralization by the values of osteocalcin (sOC) by electrochemiluminescence immunoassay. A novel marker of bone resorption, urinary osteocalcin midfragments (uMidOC), was assayed using enzyme linked immunosorbent assay (ELISA).ResultsSeveral diagnostic associations were found between the bone markers (PINP, OC, MidOC) and progressive OA expressed by TF osteophytosis. The increasing output of MidOC demonstrated several-fold higher risk for progressive TF osteophytosis [odds ratio (OR) 5.32; 95% confidence interval (CI) 1.41–20.06, P = 0.014] than other bone markers. The values of PINP had prognostic value for subsequent more severely expressed knee OA progression [r(s) = 0.460, P = 0.005].ConclusionsBone metabolism is activated in early-stage knee OA. OA progression was preceded by the enhanced bone formation (by PINP) and accompanied by the activation of bone formation (by PINP), non-collagenous bone resorption (by MidOC), as well as by changes in mineralization (by OC). All three bone markers had diagnostic value, and one of them, PINP, had also a predictive value for knee OA progression, especially for progressive osteophytosis
Alignment of galaxies relative to their local environment in SDSS-DR8
We study the alignment of galaxies relative to their local environment in
SDSS-DR8 and, using these data, we discuss evolution scenarios for different
types of galaxies. We defined a vector field of the direction of anisotropy of
the local environment of galaxies. We summed the unit direction vectors of all
close neighbours of a given galaxy in a particular way to estimate this field.
We found the alignment angles between the spin axes of disc galaxies, or the
minor axes of elliptical galaxies, and the direction of anisotropy. The
distributions of cosines of these angles are compared to the random
distributions to analyse the alignment of galaxies. Sab galaxies show
perpendicular alignment relative to the direction of anisotropy in a sparse
environment, for single galaxies and galaxies of low luminosity. Most of the
parallel alignment of Scd galaxies comes from dense regions, from 2...3 member
groups and from galaxies with low luminosity. The perpendicular alignment of S0
galaxies does not depend strongly on environmental density nor luminosity; it
is detected for single and 2...3 member group galaxies, and for main galaxies
of 4...10 member groups. The perpendicular alignment of elliptical galaxies is
clearly detected for single galaxies and for members of < 11 member groups; the
alignment increases with environmental density and luminosity. We confirm the
existence of fossil tidally induced alignment of Sab galaxies at low z. The
alignment of Scd galaxies can be explained via the infall of matter to
filaments. S0 galaxies may have encountered relatively massive mergers along
the direction of anisotropy. Major mergers along this direction can explain the
alignment of elliptical galaxies. Less massive, but repeated mergers are
possibly responsible for the formation of elliptical galaxies in sparser areas
and for less luminous elliptical galaxies.Comment: 15 pages, 15 figures, accepted for publication in A&
When renormalizability is not sufficient: Coulomb problem for vector bosons
The Coulomb problem for vector bosons W incorporates a known difficulty; the
boson falls on the center. In QED the fermion vacuum polarization produces a
barrier at small distances which solves the problem. In a renormalizable SU(2)
theory containing vector triplet (W^+,W^-,gamma) and a heavy fermion doublet F
with mass M the W^- falls on F^+, to distances r ~ 1/M, where M can be made
arbitrary large. To prevent the collapse the theory needs additional light
fermions, which switch the ultraviolet behavior of the theory from the
asymptotic freedom to the Landau pole. Similar situation can take place in the
Standard Model. Thus, the renormalizability of a theory is not sufficient to
guarantee a reasonable behavior at small distances for non-perturbative
problems, such as a bound state problem.Comment: Four page
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