scholarly journals Cell Coupling and Maturation-Promoting Factor Activity in In Vitro-Matured Prepubertal and Adult Sheep Oocytes1

2001 ◽  
Vol 65 (1) ◽  
pp. 247-252 ◽  
Author(s):  
S. Ledda ◽  
L. Bogliolo ◽  
G. Leoni ◽  
S. Naitana
Keyword(s):  
Factor Activity ◽  
Cell Coupling ◽  
Adult Sheep ◽  
Maturation Promoting Factor

Effect of steroids on cartilage metabolism "in vitro"

1986 ◽  
Vol 113 (4_Suppl) ◽  
pp. S35-S40 ◽  
Author(s):  
Marc V.L. DU CAJU ◽  
Raoul P. ROOMAN
Keyword(s):  
Growth Factor ◽  
Thymidine Incorporation ◽  
Normal Serum ◽  
Synthetic Analogue ◽  
Factor Activity ◽  
Poor Growth ◽  
Cartilage Metabolism ◽  
Glucocorticoid Administration

ABSTRACT Conditions characterized by high levels of glucocorticoids are associated with poor growth. Serum somatomedin or insulin-like growth factor activity measured by cartilage bioassay systems is low, but is generally not accompanied by a fall in somatomedin concentration. Hydrocortisone and a synthetic analogue, dexamethasone, impaired the serum stimulated "in vitro" 35S sulphate and 3H-thymidine incorporation in porcine rib cartilage at physiological concentrations. Hydrocortisone added at a concentration of 0,1 μg/ml decreased the potency of normal serum to 50 % of controls. Dexamethasone was at least 10 times more potent. Removal of "in vitro" or "in vivo" administered hydrocortisone with dextran-coated charcoal restored the sulphate and thymidine activity to normal. We conclude that physiological amounts of glucocorticoids inhibit the "in vitro" porcine cartilage metabolism. Glucocorticoid administration "in vivo" does not abolish the activity of the cartilage stimulating effect of serum but affects cartilage metabolism directly or by the induction of locally produced inhibitors of cartilage metabolism.

scholarly journals Remodeling of mouse thymocyte nuclei depends on the time of their transfer into activated, homologous oocytes

1988 ◽  
Vol 91 (4) ◽  
pp. 603-613
Author(s):  
D. Szollosi ◽  
R. Czolowska ◽  
M.S. Szollosi ◽  
A.K. Tarkowski
Keyword(s):  
Nuclear Envelope ◽  
Somatic Cell ◽  
Morphological Changes ◽  
Factor Activity ◽  
Cell Nuclei ◽  
Nuclear Envelope Breakdown ◽  
Somatic Cell Nucleus ◽  
Short Time ◽  
Nuclear Remodeling ◽  
Maturation Promoting Factor

The potential of parthenogenetically activated mouse oocytes to remodel somatic cell nuclei was studied by ultrastructural means using oocyte-thymocyte hybrids. Complete nuclear remodeling, initiated by nuclear envelope breakdown and chromosome condensation (which is followed by formation of pronucleus-like nucleus) is possible only during a short time gap between metaphase II and telophase of meiotic division. Maturation-promoting factor activity is high during this period. The thymocyte nucleus can follow the sequence of morphological changes only in concert with the development of the native nucleus and only after exposure of the chromatin to the ooplasm. If hybridization is effected with pronucleate oocytes, the thymocyte nucleus retains its interphase character but shows particular modifications in nucleolar morphology (identical to changes observed during reactivation of the nucleolus in stimulated lymphocyte) and in the activity of the nuclear envelope (blebbing). Thus the nucleus not exposed to maturation-promoting factor activity may be influenced by a ‘programme’ specific for oocyte (blebbing) and by a programme inherent in the introduced somatic cell nucleus.

Relationship between Na+ current expression and cell-cell coupling in astrocytes cultured from rat hippocampus

1991 ◽  
Vol 65 (4) ◽  
pp. 989-1002 ◽  
Author(s):  
H. Sontheimer ◽  
S. G. Waxman ◽  
B. R. Ransom
Keyword(s):  
Lucifer Yellow ◽  
Na Channel ◽  
Dye Coupling ◽  
Cell Coupling ◽  
Na Current ◽  
Na Currents ◽  
Coupled Cells ◽  
Hippocampal Astrocytes ◽  
Cell Cell

1. Cell-cell coupling between hippocampal astrocytes in culture was studied by following the intracellular spread of the low molecular weight fluorescent dye Lucifer yellow (LY). Dye coupling appeared as early as 24 h after plating, at which time approximately 20% of all astrocytes that physically contacted neighboring cells showed dye coupling. 2. The percentage of coupled cells increased with time in culture and peaked after 10 days in vitro (DIV) when approximately 50% of astrocytes showed coupling. Further time in culture, up to 20 DIV, did not increase the percentage of coupled cells. Thus, coupled and noncoupled astrocytes coexist in hippocampal cultures in approximately equal numbers. 3. Na+ currents were expressed in a subpopulation of hippocampal astrocytes and changed characteristics during in vitro development. A "neuronal type" of Na+ current, so called because of an h alpha curve that had a midpoint near -60 mV, was observed within the first 5 days post-plating. A "glial type" of Na+ current, characterized by a -25 mV shift in its h alpha curve, was only expressed after 6 days in culture. 4. Na+ current expression was restricted to hippocampal astrocytes that did not exhibit dye coupling; astrocytes that exhibited dye coupling (n = 39) did not show measurable Na+ currents. 5. The failure to see Na+ currents in coupled astrocytes cannot be explained by insufficient space-clamp since astrocytes acutely uncoupled with octanol (10 microM) did not reveal Na+ current expression. Control experiments showed that low concentrations of octanol (i.e., 10-100 microM) did not block Na+ currents; blockage of Na+ currents by octanol was only observed at high concentrations (e.g., 50-fold the concentration used for uncoupling). These observations support the idea that Na(+)-channel expression was restricted to noncoupled astrocytes. 6. The time courses for the development of cell coupling and Na+ current expression appeared to be inversely correlated and suggested a gradual increase in cell coupling in concert with a loss in Na+ current expression with time in culture.

scholarly journals Metalloproteinase inhibition and erythroid potentiation are independent activities of tissue inhibitor of metalloproteinases-1

Blood ◽  
1995 ◽  
Vol 86 (12) ◽  
pp. 4506-4515 ◽  
Author(s):  
L Chesler ◽  
DW Golde ◽  
N Bersch ◽  
MD Johnson
Keyword(s):  
Growth Factor ◽  
Tissue Inhibitor Of Metalloproteinases ◽  
Factor Activity ◽  
Erythroid Progenitors ◽  
Protease Inhibition ◽  
Tissue Inhibitor ◽  
Vitro Assay ◽  
Erythroid Precursor ◽  
Metalloproteinase Inhibitor

Tissue inhibitor of metalloproteinases-1 (TIMP-1), the major physiological matrix metalloproteinase inhibitor and a potent antimetastatic factor, also stimulates the growth of erythroid progenitors (erythroid-potentiating activity). We analyzed the relationship between the growth factor activity and protease inhibition by preparing purified TIMP-1 “knockout” proteins lacking in vitro antiproteolytic activity. The growth-stimulatory effect of these N- terminal TIMP-1 point mutants, as tested in an in vitro assay using erythroid precursors (erythroid burst-forming units) was equal to that of unmutated TIMP-1. A fully antiproteolytic C-terminal TIMP-1 truncation also stimulated growth in the erythroid burst-forming unit assay. The results indicate that the influence of TIMP-1 on erythroid precursor growth is independent of its ability to inhibit metalloproteinases. TIMP-1 is analogous to proteins that have both proteolytic and growth factor activity, such as plasmin, thrombin, and urokinase. However, TIMP-1 is novel in this regard because it is a metalloproteinase inhibitor. We show that the antiproteolytic and growth factor activities of the TIMP-1 molecule are physically and functionally distinct.

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