Additive stimulation of hepatic putrescine production by glucagon and insulin after partial hepatectomy in rats

When rats received glucagon or insulin every 2 h after partial hepatectomy (Hx), hepatic putrescine content was increased above control levels at 6 and 12 h, respectively. When the two hormones were combined, the increased levels were additive. Hepatic ornithine decarboxylase activity was above control levels at 12 h after insulin treatment. Hepatic spermidine N1-acetyltransferase activity was enhanced at 6 h only when glucagon was dosed. Putrescine administration from 0 to 4 h or from 6 to 10 h increased hepatic DNA synthesis to similar levels 22 h after Hx. These results suggest that glucagon and insulin additively stimulate hepatic putrescine production after Hx. This may explain the cooperative stimulation of liver regeneration by both hormones.     

A new hereditary single band variant of the Gc system

Summary A new single band variant (Gc Ar) or the Gc subtypes not identical with the known Gc variants has been detected in the plasma of a healthy blood donor by isoelectric focusing. Using this technique the variant is represented by a single band which has a similar isoelectric point to the Gc 1C2 anodal band. It is well known that the single band Gc phenotypes remain unaltered after neuraminidase treatment. Nevertheless, the new single band variant (Gc Ar) is altered after neuraminidase treatment as is Gc 2A3. After neuraminidase treatment, the Gc Ar band is affected and moved to the nearby position of the Gc 2 band. Investigation of the proband's family shows that the variant occurs combined with the common alleles Gc 1F, Gc 1S and that it has an autosomal dominant inheritance.     

The Water-Film Electrode: A New Device for Measuring the Characean Electro-Potential and -Conductance Distributions along the Length of the Internode

A "water-film electrode" has been developed to study time dependenciesof the distributions of electrical potential (Vm) and conductance(Gm) as a function of position along the length of a singleCharacean internode. The water-film is formed by dipping a ring-shapedAg/AgCl wire covered with an agar block into detergent-containingartificial pond water. The use of uncalcified internodes produced the following results:(1) Both Vm and Gm were relatively uniform along the internodein darkness. (2) Illumination induced hyperpolarization andincreased Gm along the entire length of the internode withinfew minutes. During this period, small electro-potential differentiationof as much as 20 mV was sometimes observed. Thereafter, severaldepolarized regions (D-regions) with highGm values appeared;as much as 100 mV of depolarization. (3) The positions of theD-regionsin light remained unchanged for several days even when the lightwas turned off for a period of more than 1 h. (4) When the internodewas partially exposed to light, the D-region appeared, or formed,only in the illuminated part. In calcified internodes electro-differentiation was inducedby illumination as it was in uncalcified ones. Slightly depolarizedregions, however, remained even in darkness. Unlike noncalcifiedinternodes, the conductance of the depolarized region was generallyless than that of the neighboring hyperpolarized regions (H-regions). (Received August 2, 1982; Accepted March 24, 1983)     

Blood clotting factor IX BM Nagoya. Substitution of arginine 180 by tryptophan and its activation by alpha-chymotrypsin and rat mast cell chymase

Factor IX BM Nagoya (IX Nagoya) is a natural mutant of factor IX responsible for severe hemophilia B. A patient with this mutant is characterized by a markedly prolonged ox brain prothrombin time. IX Nagoya was purified from the patient's plasma by immunoaffinity chromatography with an anti-factor IX monoclonal antibody column. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that treatment of IX Nagoya with factor XIa/Ca2+ resulted in cleavage only at the Arg145-Ala146 bond. Reversed-phase high performance liquid chromatography of a trypsin digest of IX Nagoya showed an aberrant peptide, which was further digested with proteinase Asp-N. Primary structure analysis of one of the Asp-N peptides revealed that Arg180 is replaced by Trp. An essentially complete (99%) amino acid sequence of IX Nagoya was obtained by sequencing fragments derived from a lysyl endopeptidase digest in which no other substitutions in the catalytic triad or substrate binding site were found. We also found that IX Nagoya is activated by alpha-chymotrypsin or rat mast cell chymase by monitoring the rate of factor X activation using a fluorogenic peptide substrate in the presence of factor VIII, phospholipids, and Ca2+. These results indicate that the substitution of Arg180 by Trp impairs the cleavage by factor XIa required for activation of this zymogen and that the substitution causes hemophilia BM.     

Possible role of sodium-hydrogen antiport in acetylcholine-induced relaxation of rat aorta.

The decreased extracellular Na concentration (25mM) attenuated vasodilator effect of acetylcholine (ACh) in norepinephrine-treated aortic ring. This attenuation was greater in the low Na medium substituted by Li, which can exchange intracellular H through Na-H antiport, as compared with that substituted by choline, which cannot. 10 microM amiloride canceled the difference between the two low Na mediums. Thus the inhibition of Na-H antiport may counteract the suppressive effect of decreased intracellular Na on ACh vasodilation, suggesting a possible role of Na-H antiport in a release of vasoactive substance(s) from endothelial cells.     

Two cage-type lupin alkaloids from Sophora franchetiana

Two new cage-type lupin alkaloids, (?)-tsukushinamine-B and tsukushinamine-C, have been isolated from the fresh epigeal parts of Sophora franchetiana, along with (?)-cytisine, (?)-N-formylcytisine, (?)-rhombifoline, (?)-anagyrine, (?)-baptifoline and (±)-ammodendrine, as well as (?)-tsukushinamine-A. The structures of these novel tsukushinamine-type lupin alkaloids were determined by spectroscopic data and partly by a chemical reaction. Variations of the alkaloid contents in the seeds, seedlings and various parts of S. franchetiana were also examined.     

Presence of a thiol protease in regenerating rat-liver nuclei. Partial purification and some properties

1. Nuclei of regenerating rat liver washed with Triton X-100 were found to contain a new protease. Since the enzymatic activity for degrading ribosomal proteins was inhibited in vivo by administration of E-64, a thiol protease inhibitor, the enzyme may participate in the degradation of newly synthesized ribosomal proteins and histones in regenerating rat liver nuclei as reported previously by us [Biochem. Biophys. Res. Commun. 75, 525-531 (1077)]. The optimum pH was 5.5. 2. The enzyme was extracted from washed nuclei and partially purified by gel filtration through Sepharose 6B. Its molecular weight was about 40 000. A maximal activity of partially purified enzyme was observed in the presence of 1 mM EDTA and 2 mM dithiothreitol at pH 5.5 It was inhibited by thio reagents, E-64, leupeptin and hevy metal ions. The enzyme degraded ribosomal proteins endoproteolytically and degraded most proteins tested as substrates, although liver cell sap proteins and serum albumin were less degraded than ribosomal proteins and histones, alpha-N-Benzoylarginine-beta-naphthylamide and benzoylarginine amide were not hydrolyzed.