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S Waters

Publications and source records attributed to S Waters.

33 records · Page 2Linked to original sources
PubMed1992

The condensing action of Mg2+, hexamminecobalt3+ and spermidine3+ on chromatin with gene regions activated by 17-beta estradiol.

1. Hepatic vitellogenin synthesis was induced by injecting 17-beta estradiol into fish. Liver nuclei were incubated with the endonuclease EcoRI at an increasing concentration of Mg2+ (0.15-1.50 mM), hexamminecobalt3+ or spermidine3+ (0.10-1.00 mM). Chromatin was separated into a 5000 g supernatant, S-fraction, and pellet fraction. 2. The release of chromatin into the S-fraction was higher for the induced than the control chromatin. Hybridization of the vitellogenin gene retained in the pellet fraction of the controls was unaffected by the individual cations. After activation of the vitellogenin gene, Mg2+ at its lowest concentration retained a high amount of the vitellogenin gene in the pellet fraction. The level of hybridization decreased by increasing the Mg2+ concentration. Retention of the gene rose by adding hexamminecobalt3+ and more so by adding spermidine3+. 3. The condensing action of spermidine3+ was extended to the activated vitellogenin gene regions of chromatin.

Animals↗
PubMed1992

Purification of the Atlantic salmon hepatic 21 kDa protein and classification as a high mobility group chromatin protein.

The 21 kDa protein of liver from Atlantic salmon (Salmo salar) has been purified. Hepatic nuclei were extracted with 0.75 M HClO4. The extracted proteins were fractionated using reversed phase high performance liquid chromatography. The purity of the protein was analysed by isoelectric focusing in the first, and SDS-polyacrylamide gel electrophoresis in the 2nd dimension. Isoelectric focusing separated the protein into 5 spots. In gel trypsin digestion after isoelectric focusing followed by SDS-polyacrylamide gel electrophoresis resulted in identical migration of the tryptic peptides. The amino acid composition of the 21 kDa protein was similar to that of high mobility group (HMG) proteins C and D from rainbow trout (Oncorhynchus mykiss). The N-terminal sequence of the amino acids 1-19 revealed a conserved region characteristic for HMG 14/17 proteins of mammals and avians, and their equivalents in rainbow trout. Considering the electrophoretic mobility, amino acid composition and N-terminal amino acid sequence it is concluded that the 21 kDa protein of Atlantic salmon is a member of the HMG protein family resembling the HMG D protein of rainbow trout.

Amino Acid Sequence↗
PubMed1990

A 21 KDa protein resides in the nucleosomes of micrococcal nuclease sensitive liver chromatin of Atlantic salmon treated with estradiol.

Atlantic salmon was treated with 17-beta-estradiol to induce the process of vitellogenesis in liver. When the isolated liver nuclei were incubated with micrococcal nuclease at increasing enzyme/DNA ratios a 21 KDa protein appeared in the nuclease sensitive chromatin, the S-fraction. After HPLC gel filtration the 21 KDa protein resided with the oligo- and mononucleosomes. The S-fraction contained vitellogenin gene sequences at low nuclease/DNA ratios. The sequences were detectable also in the mononucleosomes derived from the S-fraction. After hormone treatment the vitellogenin gene exposed a higher sensitivity to micrococcal nuclease than the hormone-untreated controls. The results indicate that the 21 KDa protein took part in the hormone-mediated changes in gene expression by modulating the structure of estradiol responsive chromatin domains including the vitellogenin gene.

Animals↗
PubMed1986

Expression of T cell receptor genes in an antigen-specific hybridoma and radiation-induced variants.

We have analyzed a series of mutants derived from a KLH-specific, I-E-restricted T hybridoma (FN1-18) which have lost antigen-reactivity while retaining both T cell receptor idiotypic determinants and the ability to respond to Con A. The variants have not gained any detectable alloreactivity, nor is there an obvious lesion in the mutants' beta chain DNA containing the utilized beta chain genes. This loss of antigen reactivity is due to a failure of stable production of the specific V beta-containing mRNA. Our results indicate that in FN1-18, the T cell receptor antigenic determinants are most likely carried by the alpha chain alone or by a complementation product of the V alpha FN1-18 with the V beta of BW5147. V beta FN1-18 represents a previously undescribed T cell receptor V region.

Animals↗
PubMed1982

Anti-immunoglobulin antibodies. III. Properties of sequential anti-idiotypic antibodies to heterologous anti-gamma globulins. Detection of reactivity of anti-idiotype antibodies with epitopes of Fc fragments (homobodies) and with epitopes and idiotopes (epibodies).

Murine anti-V region antibodies against a human monoclonal protein Gl with anti-gamma-globulin activity and bearing the Wa cross-reactive idiotype were prepared in several strains of mice. Antibodies were obtained that were specific for the Gl idiotype, the Wa cross-reactive idiotype, and for various framework antigenic determinants that were distinguished by a variety of procedures. Synthesis of such antibodies were found to be independent of MHC and Igh gene complexes. These anti-V region antibodies, produced by a majority of mouse strains investigated, also share a cross-reactive idiotype recognized by BALB/c anti-anti-V region Gl antibodies. A fraction of BALB/c anti-anti-V region Gl antibodies displayed human Fc gamma binding activity and, therefore, can be considered homobodies, as described in other systems. Two of the anti-idiotype antibodies obtained in this system exhibited a peculiar property: they interacted not only with their own antigen (IgM Gl), but also with the Fc fragment with which IgM Gl reacts. Thus, A/J anti-V region Gl antibodies bind to the human Fc gamma fragment in addition to IgM Gl. Similarly, a monoclonal CB6 F1 anti-anti-V region Gl antibody interacted with the V region of IgM Gl as well as with the syngeneic anti-V region antibodies. We called these anti-idiotypic antibodies epibodies because they interact with epitopes of the primary antigen. These homobodies and epibodies, obtained by immunization across heterologous barriers, represent new examples of recognition of the internal image of the antigen within the immune system.

Animals↗
PubMed1982

Comparative trial of cefonicid and cefamandole in the therapy of community-acquired pneumonia.

Cefonicid (Smith Kline & French Laboratories; D-75073) is a new parenteral cephalosporin with a markedly long half-life, high serum levels, and good in vitro activity against Haemophilus influenzae. Patients with community-acquired pneumonia were randomized 2:1 to receive cefonicid, 1 g daily (21 cases) or cefamandole, 1 g every 6 h (12 cases). The two groups were similar, except that the cefonicid patients were older (mean 42 versus 31 years). Peak serum levels of cefonicid averaged 133 microgram/ml after intravenous and 83 microgram/ml after intramuscular administration compared with 55 microgram/ml with intravenous cefamandole. All 9 patients on intramuscular cefonicid and 8 or 12 patients on intravenous cefonicid had trough serum levels of greater than 2.0 microgram/ml at 24 h. Sputum levels of cefonicid were usually between 2.0 and 4.0 microgram/ml and did not correlate with serum levels. Cefonicid was well tolerated, and all cefonicid patients responded clinically. Sputum cultures for H. influenzae or Streptococcus pneumoniae became negative in 6 of 7 cefamandole patients and 13 or 15 cefonicid patients. In in vitro studies, cefonicid inhibited 90% of beta-lactamase-negative h. influenzae at 0.5 microgram/ml and beta-lactamase-positive strains at 2.0 microgram/ml. Cefonicid inhibited 50% of S. pneumoniae at 1.6 microgram/ml, but required 6.4 microgram/ml to inhibit 90%. Cefonicid once a day appears to be as safe and as effective as cefamandole four times a day for therapy of community-acquired pneumonia.

Adult↗
PubMed1975

Competitive binding activity of angiotensin II analogues in an adrenal cortex radioligand-receptor assay;.

The competitive binding activities of a number of angiotensin analogues were determined in a radioligand-receptor assay employing bovine adrenal crotex homogenate and [125I] iodoangiotensin II. This assay system has been shown to provide a precise and convenient method for evaluation and comparison of the binding-inhibition potencies of angiotensin II derivatives with agonist and antagonist activities. Agonist analogues of angiotensin II showed competitive binding activities in proportion to their known biological activities upon aldosterone production by the adrenal zona glomerulosa. Thus, the [Des-Asp1] heptapeptide of angiotensin II was equipotent with the native octapeptide in terms of binding-inhibition activity, and the [Sar1] derivative of angiotensin II was more potent than the native peptide. By contrast, the [Des-Asp1, Des-Arg2] hexapeptide and the [Des-Phe8] heptapeptide showed less than 1% of the activity of angiotensin II. Angiotensin II antagonists formed by C-terminal substitution of the octapeptide with isoleucine or alanine were also found to exhibit binding-inhibition activities in proportion to their known potencies as antagonists of the action of angiotensin II upon smooth muscle. Certain antagonists, such as [1-guanidoacetic, 8-isoleucine]-angiotensin II and [1-sarcosine, 8-isoleucine]-angiotensin II displayed significantly greater binding-inhibition potency than E1Asp1, Ileu5,-angiotensin II in the adrenal receptor system. Several, such as [Sar1, Ala8]-angiotensin II and [MeAla1, Ileu8]-antiotensin II were approximately equipotent with angiotensin II, while others such as [1-succinic acid, 8-alanine]-angiotensin II and [D-Ileu8]-angiotensin II showed no significant binding-inhibition activity. The relative binding-inhibition potencies of the antagonist peptides showed a general correlation with the pA2 values of the same components determined upon the smooth muscle response of the isolated aortic strip. The binding-inhibition potency of angiotensin II antagonists was also strongly influenced by the charge of the N-terminal residue, with enhancement of activity by more basic substituents and abolition of activity by highly acidic residues. The influence of the basicity of the N-terminus upon receptor binding was also observed with the agonist analogue [Sar1]-angiotensin II, which showed a 2- to 3-fold increase in binding-inhibition potency in comparison to native angiotensin II. The significant enhancement of binding-inhibition potency by N-terminal sarcosine substitution is attributable to higher affinity of the modified peptide for the angiotensin II receptor site, and is consistent with the increased activity of [Sar1]-angiotensin II upon smooth muscle and aldosterone production in vitro. The determination of binding-inhibition activity in the adrenal radioligand receptor assay provides a valid and convenient method for analysis of the role of binding affinity in the actions of competitive antagonists upon the responses of target cells to angiotensin II.

Adrenal Cortex↗
PubMedDate not supplied

Standardisation of 11C.

The increasing use of positron emission tomography for medical imaging and the availability of short-lived positron emitters has raised concerns about the accuracy of calibration of secondary standard measurement systems and the viability of using a single long-lived positron emitter as a reference calibration source for all positron emitters. Potential problems arise because the 511 keV quanta arising from positron annihilation are not generally produced at the same point as the original disintegration. In addition, the secondary standard may also be responsive to the associated bremsstrahlung radiation. The magnitude of both effects depends on the positron end-point energy. In order to resolve these problems, it is necessary to produce absolute standards of these positron-emitting radionuclides and the work presented here details the results of such work with 11C.

Journal Article↗