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Biomedical subjects

M Christensen

Publications and source records attributed to M Christensen.

At least 163 records · Page 9Linked to original sources
PubMed1979

Structure-function studies on red pigment-concentrating hormone, II. The significance of the C-terminal tryptophan amide.

The significance of the C-terminal tryptophan residue of the red pigment-concentrating hormone (RPCH: Glu-Leu-Asn-Phe-Ser-Pro-Gly-Trp-NH2) regulating the blanching of the crustacean chromatophores has been investigated. RPCH and a number of analogues that differ only in the C-terminal part of the hormone, have been synthesized and assayed for biological activity on the shrimp Leander adspersus. It has been shown that the indole skeleton of tryptophan is an absolute requirement for the biological activity of the hormone. To provide maximum response the tryptophan must be blocked as the amide. The activity of synthetic [Tyr4]RPCH and adipokinetic hormone (AKH) purified from Schistocerca gregaria has been compared with the activity of synthetic RPCH.

Amides↗
PubMed1978

Immune complexes in retinoblastoma.

Thirteen patients with retinoblastoma were tested for circulating immune complexes using the Raji cell radioimmunoassay. Eight of 13 patients had statistically significantly increased levels of immune complexes.

Antigen-Antibody Complex↗
PubMed1978

Storage of polyvinylpyrrolidone (PVP) in tissues following long-term treatment with a PVP-containing vasopressin preparation.

The parenteral use of polyvinylpyrrolidone (PVP) leads to PVP retention in the human organism. Four case histories dealing with patients on long-term treatment with a PVP-containing vasopressin preparation are presented and the possibility of a harmful effect of the PVP storage is discussed. The presence of PVP in serum, demonstrated by lipoprotein electrophoresis, is described. Based on the literature and the present findings, a withdrawal of PVP-containing preparations for injectional purposes is advocated.

Adult↗
PubMed1978

Structure-function studies on red pigment-concentrating hormone; the significance of the terminal residues.

The significance of the terminal residues of the red pigment-concentrating hormone (RPCH: Glu-Leu-Asn-Phe-Ser-Pro-Gly-Trp-NH2) for its blanching effect on crustacean chromatophores has been investigated. The chemical synthesis of the following small analogues, starting from the C-terminal amino acid are described: Ac-Trp-NH2, Boc-Gly-Trp-NH2, Ac-Gly-Trp-NH2, Gly-Trp-NH2, Ac-Pro-Gly-Trp-NH2, Glu-Trp-NH2, Glu-Pro-Gly-Trp-NH2, Ac-Pro-Gly and Glu-Pro-Gly-NH2. Assay of the biological activity of the various synthetic compounds in the shrimp Leander adspersus has established that only the C-terminal tryptophan residue is indispensable for the blanching effect of the hormone, although elongation of the chain length improves its potency.

Animals↗
PubMed1978

N-alkylation of amino acid residues by chloromethyl groups. A potential side reaction in the solid phase peptide synthesis.

A serious side reaction in the peptide synthesis on the Merrifield resin was observed during attempts to synthesize the TMV fragment, Asn-Pro-Thr-Thr-Ala (101--105). The side reaction is consistent with N-alkylation of the amino groups by the residual chloromethyl groups on the resin, which lowers the total yield and complicates evaluation of monitoring data during the synthesis. It is shown that several amino acids can be N-alkylated in different positions in the peptide chain and in different solvents. The extent of N-alkylation is in some cases 50%.

Alkylation↗