Search results for "centrifugation"
showing 10 items of 124 documents
Isolation of Cholinergic Synaptic Vesicles from the Myenteric Plexus of Guinea-Pig Small Intestine
1980
The acetylcholine-rich myenteric plexus-longitudinal muscle preparation of the guinea-pig small intestine has been subjected to subcellular fractionation using modifications of both classical methods and that originally devised for bulk isolation of cholinergic synaptic vesicles from the electromotor nerve terminals of Torpedo marmorata by means of density gradient centrifugation in a zonal rotor. The latter method gave a vesicle fraction with the highest acetylcholine content so far recorded for a mammalian particulate fraction, 30.9 +/- S.E.M. 1.8 (5) nmol of acetylcholine . mg of protein-1. Electron-microscopical examination showed that it consisted of a homogeneous preparation of vesicl…
Tissue evacuated during joint replacement procedure as a source of mononuclear cells.
2017
Background Different cell populations from bone marrow were used in various clinical trials for cardiac diseases during last decade. Four clinical studies are ongoing in our institution and enroll patients with cardiac diseases, coronary disease, type 2 diabetes, and osteoarthritis. The density gradient is used to separate bone marrow mononuclear cells. Joint replacement procedures were associated with significant loss of tissue. Usually, excess tissue as bone marrow, peripheral blood and fat are removed to clean operation site. The aim of this study is to prove whether removed tissue during joint replacement procedure can be considered as a significant source of mononuclear cells. Methods …
Involvement of microsomal vesicles in part of the sensitivity of carnitine palmitoyltransferase I to malonyl-CoA inhibition in mitochondrial fraction…
1994
Liver mitochondrial fractions as normally isolated contain only 10-20% of total mitochondria and may not be representative of the whole mitochondrial population. This study was designed to evaluate the dependence of the sensitivity of carnitine palmitoyl-transferase I (CPT I) to malonyl-CoA inhibition in mitochondrial fractions that are not normally studied. Four fractions prepared from rat liver were found to be contaminated to different extents by microsome vesicles, on the basis of marker-enzyme activities and micrographic data. Purification of mitochondrial fractions on a Percoll gradient decreased to some extent the microsomal contamination, which was due in part to the existence of cl…
The site of fertilisation determines dorsoventral polarity but not chirality in the zebra mussel embryo
1998
The dorsoventral polarity of unequally cleaving spiralian embryos becomes established at an early stage. The factors determining the position of the dorsoventral axis are still unknown. We present data showing that the sperm entry point (SEP) in both normal development and under experimental conditions determines the position of the first cleavage furrow in Dreissena embryos. The position of the spindles at second cleavage is directed by the site of fertilisation also, and the large, dorsal D quadrant of the 4-cell stage always forms opposite the SEP. The spiral chirality at third cleavage seems to be independent of both the fertilisation point and the arrangement of the quadrants. Dextral …
Prostasome-like vesicles stimulate acrosome reaction of pig spermatozoa
2007
Abstract Background The presence of small membranous particles characterizes the male genital fluids of different mammalian species. The influence of semen vesicles, denominated prostasomes, on sperm functional properties has been well documented in humans, but their biological activity is scarcely known in other species. The present work investigated prostasome-like vesicles in pig semen for their ability to interact with spermatozoa and to affect acrosome reaction. Methods Prostasome-like vesicles have been isolated from pig seminal plasma by high-speed centrifugation and Sephadex G-200 gel chromatography. Morphology of purified vesicles has been checked by scanning electron microscopy wh…
Steroid hormone receptors in human melanoma.
1981
Human melanomas were investigated for the presence of high-affinity estrogen-, gestagen-, and glucocorticoid-binding proteins. A statistically significant difference was found for mean estrogen receptor (ER) concentrations in melanomas of male versus female origin: female origin 37.6 (0-107) fmol/mg protein, male origin 3.9 (0-8.3) fmol/mg protein. No significant difference between sexes was found for gestragen receptors: 41.5 (0-194) fmol/mg protein for melanomas of female origin versus 99 (0-362) fmol/mg protein for male. Sucrose density gradient analyses revealed specific binding for both receptor types in the 4-5 S region as well as in the 8 S region. The binding affinities were in the …
Stability of chitin synthetase in cell-free preparations of a wild-type strain and a 'slime' variant of Neurospora crassa.
1991
Chitin synthetase activity in cell-free preparations from a wild-type strain and a 'slime' variant of Neurospora crassa was monitored over many days in samples stored at 0 degrees C. Total activity in whole-cell-free extracts and low-speed supernatants from both organisms was very unstable, losing more than 90% of the initial activity on storage at 0 degrees C for 96 h. Chitin synthetase detection was not masked by chitinase activity present in the preparations. Gel-filtration chromatography of these preparations increased the stability of the activity from the 'slime' variant, whereas removal of particulate structures by high-speed centrifugation stabilized the chitin synthetase activity i…
Morphology of hybrid polystyrene-block-poly(ethylene oxide) micelles: Analytical ultracentrifugation and SANS studies
2006
Abstract Morphology and structure of aqueous block copolymer solutions based on polystyrene- block -poly(ethylene oxide) (PS- b -PEO) of two different compositions, a cationic surfactant, cetyl pyridinium chloride (CPC), and either platinic acid (H 2 PtCl 6 ⋅6H 2 O) or Pt nanoparticles were studied using a combination of analytical ultracentrifugation (AUC), transmission electron microscopy (TEM), and small angle neutron scattering (SANS). These studies combining methods contributing supplemental and analogous structural information allowed us to comprehensively characterize the complex hybrid systems and to discover an isotope effect when H 2 O was replaced with D 2 O. In particular, TEM s…
Crystal Structure of Human Filamin C Domain 23 and Small Angle Scattering Model for Filamin C 23–24 Dimer
2007
Filamin C is a dimeric, actin-binding protein involved in organization of cortical cytoskeleton and of the sarcomere. We performed crystallographic, small-angle X-ray scattering and analytical ultracentrifugation experiments on the constructs containing carboxy-terminal domains of the protein (domains 23-24 and 19-21). The crystal structure of domain 23 of filamin C showed that the protein adopts the expected immunoglobulin (Ig)-like fold. Small-angle X-ray scattering experiments performed on filamin C tandem Ig-like domains 23 and 24 reveal a dimer that is formed by domain 24 and that domain 23 has little interactions with itself or with domain 24, while the analytical ultracentrifugation …
Cockroach allergens Per a 3 are oligomers
2009
Allergens from cockroaches cause major asthma-related health problems worldwide. Among them Per a 3 belongs to the most potent allergens. Although the sequences of some members of the Per a 3-family are known, their biochemical and biophysical properties have not been investigated. Here we present for the first time a thorough structural characterization of these allergens, which have recently been tested to induce an increase of allergy specific indicators in blood of Europeans. We isolated two Per a 3 isoforms, which occur freely dissolved in the hemolymph as hexamers with molecular masses of 465+/-25kDa (P II) and 512+/-25kDa (P I). Their sedimentation coefficients (S(20,W)) were determi…