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1.
Rev Sci Instrum ; 80(8): 085108, 2009 Aug.
Article in English | MEDLINE | ID: mdl-19725682

ABSTRACT

Heat load on beamline optics is a serious obstacle for devices designed to generate pure linearly polarized photons in third generation synchrotron radiation facilities. For permanent magnet undulators, this problem can be overcome by implementing a figure-eight design configuration. As yet there has been no good method to tackle this problem for electromagnetic elliptical undulators. Here, a novel design and operational mode is suggested, which can generate pure linearly polarized photons with very low on-axis heat load. Additionally, the minimum photon energy capability of linearly polarized photons can be significantly extended by this method.

2.
Rev Sci Instrum ; 78(3): 035115, 2007 Mar.
Article in English | MEDLINE | ID: mdl-17411225

ABSTRACT

Shimming systems are required to provide sufficient field homogeneity for high resolution nuclear magnetic resonance (NMR). In certain specialized applications, such as rotating-field NMR and mobile ex situ NMR, permanent magnet-based shimming systems can provide considerable advantages. We present a simple two-dimensional shimming method based on harmonic corrector rings which can provide arbitrary multipole order shimming corrections. Results demonstrate, for example, that quadrupolar order shimming improves the linewidth by up to an order of magnitude. An additional order of magnitude reduction is in principle achievable by utilizing this shimming method for z-gradient correction and higher order xy gradients.

3.
J Synchrotron Radiat ; 9(Pt 4): 270-4, 2002 Jul 01.
Article in English | MEDLINE | ID: mdl-12091739

ABSTRACT

A new X-ray undulator has been designed and constructed which produces linearly polarized X-rays in which the plane of polarization can be oriented to a user selectable angle, from horizontal to vertical. Based on the Apple-II elliptically polarizing undulator (EPU), the undulator rotates the angle of the linear polarization by a simple longitudinal motion of the undulator magnets. Combined with the circular and elliptical polarization capabilities of the EPU operating in the standard mode, this new undulator produces soft X-ray radiation with versatile polarization control. This paper describes the magnetic structure of the device and presents an analysis of the magnetic field with varying undulator parameters. The variable linear polarization capability is then exhibited by measuring the X-ray absorption spectrum of an oriented polytetrafluoroethylene thin film. This experiment, which measures the linear dichroism of the sample at two peaks near the C 1s absorption edge, demonstrates the continuous polarization rotation capabilities of the undulator.

5.
Bull Med Libr Assoc ; 77(1): 55, 1989 Jan.
Article in English | MEDLINE | ID: mdl-16017908
6.
Endocrinology ; 121(2): 449-58, 1987 Aug.
Article in English | MEDLINE | ID: mdl-2439316

ABSTRACT

A form of insulin-like growth factor II (IGF-II) with a mol wt of 15,000 has been purified to homogeneity from human Cohn fraction IV1-4. This protein has an amino-terminal sequence through the first 28 residues that is identical to 7.5K IGF-II. The amino acid composition of 15K IGF-II, however, indicates that its carboxyl-terminal region may be different from that predicted from the analysis of IGF-II cDNA clones. The affinities of 15K IGF-II for receptors on rat placental membranes and for an IGF-binding protein that was isolated from the medium of cultured buffalo rat liver cells were similar to those of the 7.5K form of the growth factor. A best-fit analysis of data from the binding of the two mol wt forms of IGF-II to receptors on rat placental membranes by the LIGAND program was consistent with a model in which 7.5K and 15K IGF-II bound to one site with Kd values of 0.27 +/- 0.03 and 0.38 +/- 0.04, respectively. There was an indication that 15K IGF-II also bound to a second low affinity site on the membrane. In mitogenesis assays performed on human fibroblasts isolated from the skin of two fetuses of an early gestational age, 15K IGF-II stimulated the incorporation of [3H]thymidine into DNA at a half-maximal concentration, i.e. ED50, of 5.7 and 5.0 nM. In these experiments, the ED50 values for 7.5K IGF-II were 8.7 and 15 nM.


Subject(s)
Insulin-Like Growth Factor II/isolation & purification , Somatomedins/isolation & purification , Amino Acid Sequence , Amino Acids/analysis , Animals , Binding, Competitive , Carrier Proteins/metabolism , Chromatography , DNA/biosynthesis , Electrophoresis, Polyacrylamide Gel , Female , Fibroblasts/metabolism , Humans , Insulin-Like Growth Factor Binding Proteins , Insulin-Like Growth Factor II/metabolism , Insulin-Like Growth Factor II/pharmacology , Molecular Weight , Peptide Fragments , Placenta/metabolism , Pregnancy , Rats , Receptor, Insulin/metabolism , Receptors, Somatomedin
7.
Biochemistry ; 22(22): 5074-84, 1983 Oct 25.
Article in English | MEDLINE | ID: mdl-6652057

ABSTRACT

Salmon, porcine, and human calcitonins interact with phosphatidylglycerol to form water-soluble complexes, but these peptides do not interact with the zwitterionic lipids phosphatidylcholine or sphingomyelin. The calcitonins are more helical in the presence of dimyristoylphosphatidylglycerol than in its absence, but human calcitonin is considerably less helical than the other two, particularly in the presence of the lipid. This may explain the previously reported faster rate of degradation of human compared with salmon calcitonin in vivo. The ability of human calcitonin to solubilize dimyristoylphosphatidylglycerol and to alter the phase transition properties of this phospholipid while maintaining a low content of helix indicates that the presence of an amphipathic helix is not a requirement for these effects. The binding of salmon calcitonin to dimyristoylphosphatidylglycerol has been studied by determining the dependence of the circular dichroism properties of the peptide on the concentration of lipid. At 25 degrees C, salmon calcitonin binds to five molecules of dimyristoylphosphatidylglycerol with an affinity constant of 1 X 10(5) M-1. Little change in these parameters is observed at 38 degrees C, and the complex is stable over a wide range of temperatures both above and below the phase transition temperature. The rate of reaction of salmon calcitonin with dimyristoylphosphatidylglycerol is rapid at or above the phase transition temperature of the lipid but not at low temperatures. Salmon calcitonin also interacts with egg phosphatidylglycerol. These results demonstrate that salmon calcitonin can react with phosphatidylglycerol at or above its phase transition temperature to form complexes which are at least kinetically stable both above and below the phase transition temperature. Salmon calcitonin can solubilize mixtures of dimyristoylphosphatidylglycerol and dimyristoylphosphatidylcholine containing 25% or more of the former phospholipid. The helical content of the peptide in the presence of these lipid mixtures is dependent on the fraction of the lipid which is phosphatidylglycerol, with larger fractions of this lipid leading to the formation of a higher helical content. At 25% phosphatidylglycerol, salmon calcitonin can solubilize the lipid mixture without much increase in the helix content of the peptide, again demonstrating that an amphipathic helical structure is not required for the solubilization of phospholipids. Ionic bonding appears to be an important component in the binding of the cationic calcitonins to phospholipids. Salmon calcitonin binds to the acidic phospholipids phosphatidylinositol and phosphatidic acid, but not to zwitterionic phospholipids. In addition, high concentrations of NaCl cause the dissociation of the complex between salmon calcitonin and dimyristoylphosphatidylglycerol.(ABSTRACT TRUNCATED AT 400 WORDS)


Subject(s)
Calcitonin/metabolism , Phospholipids/metabolism , Animals , Chemical Phenomena , Chemistry, Physical , Humans , Phosphatidylglycerols/metabolism , Protein Binding , Protein Conformation , Salmon , Species Specificity , Swine
8.
Jpn J Pharmacol ; 31(1): 53-60, 1981 Feb.
Article in English | MEDLINE | ID: mdl-7253344

ABSTRACT

Rat brain particulate fraction was found to contain binding sites for 125I-Salmon Calcitonin-I (125I-SCT). Maximum binding occurred in the physiological pH range of 7.25-7.5. The binding reaction proceeded in a temperature-dependent manner. Binding sites were broadly distributed among the various rat brain regions and considerable regional differences existed in the affinity and density as detected by Scatchard analysis. The highest affinity was recorded in the case of the hypothalamus and the lowest in the case of the cerebellum. The KD (nM) and Bmax (pmole/mg protein) estimated for the binding to four regions were as follows: hypothalamus: 1.4 and 0.19, midbrain, hippocampus plus striatum: 1.5 and 0.08, pons plus medulla oblongata: 3.0 and 0.15 and cerebellum: 8.3 and 0.20. Using a particulate fraction of rat brain void of cerebellum and cortices, a binding assay for calcitonins was developed. Binding of 125I-SCT was inhibited by unlabeled salmon, [Asu1,7]-eel and porcine calcitonins in a dose-dependent manner and the IC50s were 2.0, 8.0 and 30 nM, respectively. The IC50s were comparable to those estimated using a kidney particulate fraction. Human calcitonin, beta-endorphin and substance P were weak inhibitors of the binding. Other peptides, drugs and putative neurotransmitters tested (totally 23 substances) failed to inhibit the binding at concentrations of 1.0 microM. The physiological significance of brain binding sites for calcitonin, with the possibility that the brain may possess endogenous ligands for these sites are discussed.


Subject(s)
Brain/metabolism , Calcitonin/metabolism , Animals , Bacitracin/pharmacology , Binding Sites , Humans , In Vitro Techniques , Iodine Radioisotopes , Male , Rats , Salmon
9.
Biochemistry ; 19(4): 790-7, 1980 Feb 19.
Article in English | MEDLINE | ID: mdl-7188854

ABSTRACT

Somatomedin-C (SM-C) was purified from Cohn fraction IV of human plasma by a series of steps which included cation-exchange chromatography, gel filtration, isoelectric focusing, and reverse-phase high-pressure liquid chromatography. The peptide isolated contained 10,142 units/mg, as judged by a radioimmunoassay, representing a 780,000-fold purification from native plasma. The isolated peptide was basic (pI 8.1-8.5) and was judged to be no less than 90% pure. The best fit for integral amino acids was obtained with 78 residues. Limited sequence data were obtained on the N terminus and on five fragments obtained by tryptic digestion after blocking the lysine residues. Three of these fragments and the N terminus could be aligned with portions of insulin-like growth factor I (IGF-I). Of the 25 residues so aligned, 22 were identical with IGF-I. In addition, two tryptic fragments were obtained which are not present in the sequence of IGF-I. SM-C and IGF-I produced identical curves of displacement in radioimmunoassay and radioreceptor assays for SM-C and in an insulin radioreceptor assay. The potencies of SM-C and IGF-I in these assays differed significantly from IGF-II, somatomedin-A, and several preparations of multiplication stimulating activity. At a concentration of 1 ng/mL, SM-C stimulated the progression of Balb/c 3T3 cells into DNA synthesis and when injected in vivo restored mitosis in lens epithelium of hypophysectomized frogs.


Subject(s)
Somatomedins/blood , Amino Acid Sequence , Amino Acids/analysis , Humans , Hypopituitarism/blood , Insulin-Like Growth Factor I , Molecular Weight , Peptide Fragments/analysis , Radioimmunoassay , Radioligand Assay , Somatomedins/isolation & purification , Spectrophotometry, Ultraviolet
13.
Science ; 170(3961): 974-7, 1970 Nov 27.
Article in English | MEDLINE | ID: mdl-17834612

ABSTRACT

Aerial, surface, and underwater investigations reveal that natural seeps off Coal Oil Point, California, introduce about 50 to 70 barrels (approximately 8,000 to 11,000 liters) of oil per day into the Santa Barbara Channel. The resulting slicks are several hundred meters wide and are of the order of 10(-5) centimeters thick; tarry masses within these slicks frequently wash ashore.

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