Fructose-1,6-diphosphate reduces acute ECG changes due to doxorubicin in isolated rat heart

Doxorubicin (DXR) (0.17 x 10(-4) M) induces an acute cardiotoxicity in isolated rat heart; there is a progressive widening of the S alpha T segment, with a decrease in force derivatives and in the coronary flow. Concurrent perfusion with fructose-1,6-diphosphate (FDP) (10(-5)-10(-4) M) dose-dependently reduces the S alpha T enlargement but fails to affect the reduction in force derivatives and coronary flow. The target of cardiac protection by FDP might be the ionic mechanisms underlying the action potential configuration.     

Shortening velocity of single muscle cells isolated from a molluscan smooth muscle

Summary The maximal unloaded shortening velocity (V_max) of smooth muscle cells isolated from the pedal retractor muscle ofMytilus was more than twice as large as that of the whole muscle, suggesting the presence of extracellular components which resist the contraction of the whole muscle. The V_max of the isolated cells was almost constant at cell lengths ranging between 0.5 and 0.831₀ (1₀, optimal length for tension generation) indicating that the intracellular resistance to contraction is negligible within this range of lengths.     

Cloning and expression in E. coli of the malarial sporozoite surface antigen gene from Plasmodium knowlesi

The malarial sporozoite, the infective stage found in the salivary gland of the insect vector, bears highly immunogenic surface antigen(s). Repeated exposure to irradiated sporozoites induces protection against malaria in several host species, including man. Further, monoclonal antibodies that confer passive immunity react with the immunogenic surface determinants of different sporozoite species. One approach to prevent malaria, therefore, would be to produce a vaccine that induces high titres of circulating antibodies against the sporozoite surface determinant(s). However, production of such a vaccine has not been possible since sporozoites cannot be cultivated in vitro and, therefore, only limited amounts of surface antigen may be obtained. To overcome this problem, we have prepared mRNA from Plasmodium knowlesi-infected mosquitoes to construct a cDNA library. From this library we have isolated a clone that expresses the sporozoite surface antigen as a beta-lactamase fusion protein in the plasmid pBR322. This is the first potentially protective malarial antigen to be cloned by recombinant DNA technology.     

In vivo effects of epinephrine in a freshwater fish

Summary In vivo effects of epinephrine were investigated in a freshwater teleost,Barbus conchonius Hamilton. Fish given 2 mg/kg epinephrine in a single i.m. dose showed significant hypocholesterolemia and elevated, liver and kidney cholesterol levels 1–8 h postinjection. Plasma amino nitrogen evinced a transient yet significant fall at 2 h followed by a significant increase after 24 h. A marked reduction occurred in the plasma FFA and organic PO₄ levels after 1–8 h. The results offer little evidence for a lipolytic effect of epinephrine in this species, and the changes in metabolite levels are attributable, in part, to the catecholamineinduced modification of insulin secretion.N.K. thanks the U.G.C. for the award of a research fellowship.     

A technique for establishing parabiosis between houseflies (Musca domestica L.)

Zusammenfassung Es wird eine neue, sehr einfache Methode zur Erzeugung parabiotischer, 12–24 h lang lebensfähiger Fliegenpaare (Musca domestica L.) beschrieben.

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The author wishes to thank Prof.K. N. Saxena for encouragement.     

Side-chain hydroxylation in the biosynthesis of β-ecdysone (20-hydroxyecdysone) in the blowflyCalliphora stygia

Résumé Dans la mouche a viandeCalliphora stygia le 25-hydroxycholesterol et le (22R)-22-hydroxycholesterol sont incorporés a la -ecdysone (20-hydroxy-ecdysone) beaucoup moins qu'au cholesterol et ne sont donc probablement pas des précurseurs de cette hormone.