Your browser doesn't support javascript.
loading
Show: 20 | 50 | 100
Results 1 - 20 de 22
Filter
Add more filters










Publication year range
1.
Biomaterials ; 21(14): 1471-81, 2000 Jul.
Article in English | MEDLINE | ID: mdl-10872776

ABSTRACT

Platelet adhesion and spreading is suppressed when a poly(2-methoxyethylacrylate) (PMEA) surface is used, compared with other polymer surfaces. To clarify the reason for this suppression, the relationship among the amount of the plasma protein adsorbed onto PMEA, its secondary structure and platelet adhesion was investigated. Poly(2-hydroxyethylmethacrylate) (PHEMA) and polyacrylate analogous were used as references. The amount of protein adsorbed onto PMEA was very low and similar to that absorbed onto PHEMA. Circular dichroism (CD) spectroscopy was applied to examine changes in the secondary structure of the proteins after adsorption onto the polymer surface. The conformation of the proteins adsorbed onto PHEMA changed considerably, but that of proteins adsorbed onto PMEA differed only a little from the native one. These results suggest that low platelet adhesion and spreading are closely related to the low degree of the denaturation of the protein adsorbed onto PMEA. PMEA could be developed as a promising material to produce a useful blood-contacting surface for medical devices.


Subject(s)
Acrylates/chemistry , Acrylates/metabolism , Biocompatible Materials , Blood Proteins/metabolism , Platelet Adhesiveness , Polymers/chemistry , Polymers/metabolism , Adsorption , Biocompatible Materials/chemistry , Blood Platelets/physiology , Blood Platelets/ultrastructure , Blood Proteins/chemistry , Circular Dichroism , Humans , In Vitro Techniques , Kinetics , Microscopy, Electron, Scanning , Polyhydroxyethyl Methacrylate/chemistry , Protein Binding , Protein Structure, Secondary , Serum Albumin, Bovine/chemistry , Serum Albumin, Bovine/metabolism
2.
Genes Dev ; 7(11): 2246-57, 1993 Nov.
Article in English | MEDLINE | ID: mdl-8224850

ABSTRACT

Transcription factor IIA has been shown to interact with the TATA-binding protein and to act early during preinitiation complex formation. The human factor is composed of three subunits (alpha, beta, gamma). A human cDNA clone encoding the largest subunit of TFIIA (alpha) was isolated. The recombinant alpha polypeptide, together with the beta and gamma subunits, was capable of reconstituting TFIIA activity. Studies using antibodies raised against recombinant alpha polypeptide demonstrate that TFIIA can be an integral component of the preinitiation complex. We demonstrate that TFIIA not only interacts with TBP but also can associate with the TFIID complex. Functional assays establish that TFIIA has no apparent role in basal transcription but plays an important role in activation of transcription. Interestingly, amino acid sequence analyses of the beta-subunit demonstrate these residues to be entirely contained within the carboxyl terminus of the cDNA clone encoding the alpha-subunit.


Subject(s)
DNA, Complementary/isolation & purification , Transcription Factors/biosynthesis , Transcription Factors/genetics , Amino Acid Sequence , Base Sequence , Blotting, Western , Chromatography, Ion Exchange , Cloning, Molecular , DNA, Complementary/metabolism , DNA-Binding Proteins/biosynthesis , DNA-Binding Proteins/metabolism , Humans , Macromolecular Substances , Molecular Sequence Data , Molecular Weight , Recombinant Proteins/biosynthesis , Recombinant Proteins/isolation & purification , Recombinant Proteins/metabolism , Saccharomyces cerevisiae/genetics , Saccharomyces cerevisiae/metabolism , Sequence Homology, Amino Acid , Transcription Factor TFIIA , Transcription Factors/metabolism , Transcription, Genetic
3.
Life Sci ; 53(11): 893-900, 1993.
Article in English | MEDLINE | ID: mdl-8366756

ABSTRACT

We studied the effect of OP-41483.alpha-CD, a stable prostacyclin analog, on clamp-induced endothelial injury in rats. The injury was assessed by vascular Evans blue leakage and using a scanning electron microscope. OP-41483.alpha-CD significantly reduced the Evans blue leakage at doses of 30 and 100 ng/kg/min. PGE1.CD was also found to show an equipotent inhibitory action on the dye leakage. From scanning electron microscopic observations, a moderate degree of intimal defects, microvillous projections and platelet adhesions at the luminal surface were seen in the specimens from OP-41483.alpha-CD (30 and 100 ng/kg/min) treated rats. Furthermore, OP-41483.alpha-CD, PGE1.CD and Dibutyryl cyclic AMP (DbcAMP) were found to accelerate a proliferation of cultured bovine endothelial cells in a dose-dependent manner in vitro. Taken together, these data indicate that the endothelial regenerative effect of OP-41483.alpha-CD could contribute to healing of clamp-induced endothelial injury and it may be an important therapeutic drug to protect vascular intimal injury.


Subject(s)
Cyclodextrins/pharmacology , Endothelium, Vascular/drug effects , Epoprostenol/analogs & derivatives , Epoprostenol/pharmacology , alpha-Cyclodextrins , Animals , Carotid Arteries/drug effects , Carotid Arteries/ultrastructure , Carotid Artery Injuries , Cell Division , Constriction , Endothelium, Vascular/injuries , Endothelium, Vascular/ultrastructure , Epoprostenol/chemistry , Evans Blue , Male , Microscopy, Electron, Scanning , Rats , Rats, Wistar
4.
J Comp Pathol ; 106(1): 1-8, 1992 Jan.
Article in English | MEDLINE | ID: mdl-1556253

ABSTRACT

Experiments were conducted on 44 captive Japanese newts (Cynops pyrrhogaster) to test the hypothesis that ultraviolet (UV) irradiation might inhibit growth or induce regression of spontaneous skin papillomas of probable viral origin. An empirically derived exposure to UV irradiation (42 microW per cm2 per day) induced reduction of papilloma size which began approximately 4 weeks after irradiation was initiated. This regression included histological evidence of tissue vacuolization and cellular necrosis of papillomatous epithelium. These findings, taken together with previous data on seasonal, temperature and geographical influences on papilloma prevalence, lend support to the notion that solar UV radiation may modulate papilloma prevalence in the natural environment, possibly by direct effects on viral infection.


Subject(s)
Papilloma/pathology , Papilloma/radiotherapy , Skin Neoplasms/pathology , Skin Neoplasms/radiotherapy , Animals , Cell Transformation, Neoplastic/pathology , Cell Transformation, Neoplastic/radiation effects , Dose-Response Relationship, Radiation , Female , Male , Papilloma/mortality , Salamandridae , Skin Neoplasms/mortality , Ultraviolet Rays
5.
J Biol Chem ; 264(29): 17416-21, 1989 Oct 15.
Article in English | MEDLINE | ID: mdl-2551901

ABSTRACT

EDTA-treated microsomes prepared from rat brain mainly consisted of sealed membrane vesicles 200-500 nm in diameter and were rich in both Cl- -ATPase and Na+,K+-ATPase activities. Such Cl- -ATPase-rich membrane vesicles accumulated Cl- in an ATP-dependent and osmotically reactive manner in the presence of 1 nM ouabain. The Cl- uptake was maximally stimulated by ATP with a Km value of 1.5 mM; GTP, ITP, and UTP partially stimulated Cl- uptake, but CTP, beta, gamma-methylene ATP, ADP, and AMP did not. The ATP-dependent Cl- uptake was accelerated by an increase in the medium Cl- concentration with a Km value of 7.4 mM. Such stimulation of Cl- uptake by ATP was dependent on the pH of the medium, with an optimal pH of 7.4, and also on the temperature of the medium, with an optimal range of 37-42 degrees C. Ethacrynic acid dose dependently inhibited the ATP-dependent Cl- uptake with a concentration for half-maximal inhibition at 57 microM. N-ethylmaleimide (0.1 mM) completely inhibited and sodium vanadate (1 mM) partially inhibited the ATP-dependent Cl- uptake. The membrane vesicles did not accumulate H+ in the Cl- uptake assay medium. The ATP-dependent Cl- uptake profile agreed with that of Cl- -ATPase activity reported previously (Inagaki, C., Tanaka, T., Hara, M., and Ishiko, J. (1985) Biochem. Pharmacol. 34, 1705-1712), and this strongly supports the idea that Cl- -ATPase in the brain actively transports Cl-.


Subject(s)
Adenosine Triphosphate/pharmacology , Brain/metabolism , Chlorides/metabolism , Membrane Proteins/metabolism , Adenosine Triphosphatases/metabolism , Animals , Anion Transport Proteins , Cell Membrane/metabolism , Chloride Channels , Ethylmaleimide/pharmacology , Hydrogen-Ion Concentration , Male , Microsomes/metabolism , Nucleotides/pharmacology , Rats , Rats, Inbred Strains , Temperature , Vanadates/pharmacology
6.
J Bacteriol ; 171(8): 4514-7, 1989 Aug.
Article in English | MEDLINE | ID: mdl-2753865

ABSTRACT

Chromosomes of the halophilic archaebacterium Halobacterium salinarium were examined by electron microscopy after being spread onto water. The major part of the chromosomal DNA was associated with protein particles with diameter of 9.4 nm, arranged tandemly along the DNA fibers. Thus, the primary structure of the chromosome resembles that of eucaryote chromosomes.


Subject(s)
Chromosomes, Bacterial/ultrastructure , Halobacterium/ultrastructure , Nucleosomes/ultrastructure , Animals , Chromatin/ultrastructure , Liver/ultrastructure , Microscopy, Electron/methods , Rats
7.
Biochem Biophys Res Commun ; 160(2): 469-73, 1989 Apr 28.
Article in English | MEDLINE | ID: mdl-2719675

ABSTRACT

ATP-dependent Cl- uptake by membrane vesicles from the rat brain plasma membrane fractions was not affected by the addition of 40 mM of K+, Na+ or HCO3- to the assay medium. Na+ and K+ did not alter the uptake even in the presence of a K+ ionophore, valinomycin (10 microM), or a H+/K+ exchanger, nigericin (10 microM), whereas in the presence of both of these ionophores, K+, but not Na+, reduced the Cl- uptake. Inhibitors of proton pump activity, N,N'-dicyclohexylcarbodiimide (1 mM) and 5-(N,N-hexamethylene)amiloride (40 microM), however, did not affect the Cl- uptake. These findings suggest the presence of a primary Cl- transport system probably associated with passive H+ flux in the brain plasma membranes.


Subject(s)
Adenosine Triphosphate/physiology , Brain/metabolism , Carbodiimides/pharmacology , Chlorides/metabolism , Dicyclohexylcarbodiimide/pharmacology , Intracellular Membranes/metabolism , Animals , Biological Transport/drug effects , Brain/drug effects , Cell Membrane/drug effects , Cell Membrane/metabolism , Cell Membrane Permeability/drug effects , Intracellular Membranes/drug effects , Male , Osmolar Concentration , Rats , Rats, Inbred Strains
8.
Biochem Biophys Res Commun ; 154(1): 108-12, 1988 Jul 15.
Article in English | MEDLINE | ID: mdl-2969237

ABSTRACT

Uptake of Cl- by plasma membrane vesicles from the rat brain was stimulated by ATP at 37 degrees C, but not by beta, gamma-methylene ATP or at 0 degrees C. The addition of Triton X-100 or sucrose to the incubation medium diminished the ATP-stimulated Cl- uptake, suggesting that Cl- was transported across the membranes into the intravesicular space. This ATP-stimulated Cl- uptake was not affected by 1 mM ouabain. 1 microM oligomycin, 0.1 mM gamma-aminobutyric acid or 0.1 mM picrotoxin. Thus, non-mitochondrial ATP-driven Cl- transport through a system other than Na, K-ATPase or Cl- channels occurs in neuronal plasma membrane vesicles.


Subject(s)
Adenosine Triphosphate/pharmacology , Brain/metabolism , Chlorides/metabolism , Adenosine Triphosphatases/metabolism , Animals , Anion Transport Proteins , Biological Transport/drug effects , Cell Membrane/drug effects , Cell Membrane/metabolism , Kinetics , Microsomes/enzymology , Rats
10.
Cell Differ ; 20(1): 11-6, 1987 Jan.
Article in English | MEDLINE | ID: mdl-3815527

ABSTRACT

DNA was extracted from embryos of the sea urchin, Hemicentrotus pulcherrimus, at the S phase and examined by electron microscopy. We detected replication microbubbles with a mean size of 404 bases, in addition to replication macrobubbles of more than 1.0 kilobase (kb) in length. Seventy-five percent of the center-to-center distances of the microbubbles were 0.6-1.8 kb with a mean of 1.2 kb. Forty-five percent of the microbubbles were arranged as clusters of four or five microbubbles. These results suggest that at least 34% of the initiation sites for DNA replication are present on a DNA molecule in clusters in which the sites are arranged at 1.2-kb intervals.


Subject(s)
DNA Replication , DNA/ultrastructure , Embryo, Nonmammalian/physiology , Animals , Embryo, Nonmammalian/cytology , Interphase , Microscopy, Electron/methods , Sea Urchins/embryology
11.
Nucleic Acids Res ; 14(23): 9509-19, 1986 Dec 09.
Article in English | MEDLINE | ID: mdl-3797246

ABSTRACT

Newly synthesized DNA was separated from the bulk of the DNA by pulse-labeling with BUdR and centrifugation in an alkaline CsCl buoyant density gradient. The content of histone gene in the newly synthesized DNA was determined by DNA dot hybridization. The gene contents in DNA replicated during the early half of S phase and during the whole S phase were compared. Results showed that histone genes were replicated during the first half of the S phase in embryos in the early cleavage stage.


Subject(s)
DNA Replication , Histones/genetics , Interphase , Animals , DNA/analysis , Nucleic Acid Hybridization , Sea Urchins/embryology , Time Factors
12.
J Biochem ; 99(3): 931-8, 1986 Mar.
Article in English | MEDLINE | ID: mdl-3519596

ABSTRACT

Protease activity was extracted from sea urchin sperm with 1% Triton X-100 and partially purified by DEAE-cellulose and Sephadex G-100 chromatography. The enzyme preferentially degraded histone H1, while showing only a weak activity toward other histones. Heat-denatured casein and bovine serum albumin were not digested by this enzyme under the present experimental conditions. This protease hydrolyzed only Boc-Val-Leu-Lys-MCA among various peptidyl-MCAs. The optimal pH ranged from 7 to 11. Its molecular weight was about 41,000. Among various known inhibitors of proteases, only omicron-phenanthroline effectively inhibited the activity. The enzyme was stimulated by Zn2+ or Co2+. It was inactivated by omicron-phenanthroline but could be reactivated by the addition of Zn2+ or Co2+. Therefore, this protease seems to be a metalloprotease dependent on Zn2+ or Co2+. The insensitivity of this enzyme to phosphoramidon and its very restricted substrate specificity suggest that this enzyme is very different from other metalloproteases described hitherto.


Subject(s)
Histones/metabolism , Peptide Hydrolases/isolation & purification , Spermatozoa/enzymology , Zinc/pharmacology , Animals , Cobalt/pharmacology , Hydrogen-Ion Concentration , Male , Molecular Weight , Protease Inhibitors/pharmacology , Sea Urchins , Substrate Specificity , Temperature
13.
Cell Differ ; 18(1): 45-9, 1986 Jan.
Article in English | MEDLINE | ID: mdl-3940661

ABSTRACT

The effects of ultraviolet light (UV) on the gastrulation of sea urchin embryos were examined. The results suggest that gastrulation is inhibited by UV irradiation and that stage sensitivity to UV suppression of gastrulation changes biphasically: higher sensitivity at early and late blastula, and lower sensitivity at the mid-blastula stages. The UV-induced inhibition of gastrulation was completely reversible by subsequent exposure to visible light.


Subject(s)
Cell Differentiation/radiation effects , Embryo, Nonmammalian/radiation effects , Gastrula/physiology , Animals , Blastocyst/cytology , Blastocyst/physiology , Blastocyst/radiation effects , Embryo, Nonmammalian/cytology , Embryo, Nonmammalian/physiology , Gastrula/cytology , Gastrula/radiation effects , Sea Urchins , Time Factors , Ultraviolet Rays
SELECTION OF CITATIONS
SEARCH DETAIL
...