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Biomedical subjects

T R Norton

Publications and source records attributed to T R Norton.

At least 37 records · Page 2Linked to original sources
PubMed1977

Antileukemia activity in the Osillatoriaceae: isolation of Debromoaplysiatoxin from Lyngbya.

Chloroform extracts of several seaweeds, of the family Oscillatoriaceae, from Enewetak Atoll, Marshall Islands, display activity against P-388 lymphocytic mouse leukemia. A P-388 active compound, debromoaplysiatoxin, has been isolated from Lyngbya gracilis and characterized. This compound also has dermonecrotic activity and may be the dermatitis-producing substance in L. majuscula, the causative agent of "swimmers' itch" outbreaks in Hawaiian waters.

Animals↗
PubMed1977

Amino acid sequence of the Anthopleura xanthogrammica heart stimulant, anthopleurin A.

A highly potent heart stimulant, anthopleurin A, from Anthopleura xanthogrammica was shown to exist as a single polypeptide chain consisting of 49 amino acid residues. The sequence of the peptide was shown to be: Gly-Val-Ser-Cys-Leu-Cys-Asp-Ser-Asp-Gly-Pro-Ser-Val-Arg-Gly-Asn-Thr-Leu-Ser-Gly-Thr-Leu-Trp-Leu-Tyr-Pro-Ser-Gly-Cys-Pro-Ser-Gly-Trp-His-Asn-Cys-Lys-Ala-His-Gly-Pro-Thr-Ile-Gly-Trp-Cys-Cys-Lys-Gln as judged by Edman degradation of the carboxymethylcysteine derivative and the tryptic peptides obtained from the derivative. Although six carboxymethylcysteine residues were present in the polypeptide, no cysteine residues were detectable in the native protein, indicating that there are three cystine residues in anthopleurin A.

Amino Acid Sequence↗
PubMed1976

A polypeptide (AP-A) from sea anemone (Anthopleura xanthogrammica) with potent positive inotropic action.

Anthopleurin-A (AP-A), a polypeptide with MW ca. 5500 (53 amino acids), isolated from the sea anemone, Anthopleura xanthogrammica (Brandt), elicited a potent positive inotropic effect but without an accompanying chronotropic effect on the isolated cardiac muscles of rat, rabbit, guinea pig and cat. Similarly in dogs and cats in situ, i.p. injections of AP-A increased the contractile force without effect on heart rate or blood pressure. The cardiotonic potency for AP-A was equivalent to that of isoproterenol but much greater than that for ouabain or glucagon on the isolated cardiac muscle. AP-A increased the contractile force (cardiac output) and decreased atrial pressure in dog heart during pentobarbital-induced failure. This inotropic effect was not inhibited by propranolol pretreatment. The Ca++ requirement to restore the contractile force was less in AP-A-treated than in ouabain or isoproterenol-treated tissues. After AP-A treatment, the cardiac contractility was more resistant to hypoxia and to low or high temperature stress than ouabain-treated or control preparations. AP-A at 5 10(-9) M increased the duration of the action potential, its mean rate of rise and conduction in the guinea-pig atria and ventricles. At the maximum effective concentration, AP-A did not inhibit Na+, K+-activated adenosine triphosphatase, phosphodiesterase (high Km and low Km) and cyclic 3',5'-adenosine monophosphate content of guinea-pig heart. AP-A (5 X 10(-8) to 5 X 10(-7) M) neither contracted nor relaxed the isolated vascular smooth muscle. The results suggest that AP-A may be useful in the clinical management of cardiac failure and as an experimental tool to study the pharmacology and physiology of cardiac muscle.

3',5'-Cyclic-AMP Phosphodiesterases↗
PubMed1970

Antitumor activity in mice of tentacles of 2 tropical sea annelids.

Crude extracts of tentacles of two polychaetous annelids completely inhibit growth of Erlich ascites tumor in 60 to 100 percent of treated mice. Dialyzed extracts of one of these annelids, Lanice conchilega, show activity in the retentate after pronase digestion, suggesting that antitumor activity is associated with a nonprotein component of the crude tentacle extract.

Animals↗