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.     

The effect of shock on blood oxidation-reduction potential

Oxidation-reduction (redox) potential measurements were made in the blood of rabbits subjected to hemorrhagic shock followed by treatment with a mild oxidizing agent (albumin). Control redox potential reading corrected for pH was –8.8±1.3 millivolts (mV) in arterial blood (A) and –18.0±2.0 mV in venous blood (V). This A-V difference indicated that hydrogen equivalents coming from muscle and other tissues were partially consumed in the lungs. A 20-mV drop on the V and a 13 mV on the A side was seen after shock. This did not fully return to control 2 h after return of the shed blood. Infusion of 2 g of albumin/kg/h raised the V redox potential to control, but it returned to untreated levels when the albumin was discontinued. The reductive load imposed on the animal by shock appeared to be large and not readily reversed by reperfusion or by the quantity of albumin given. Thus, it may be concluded that cellular respiration had not been adequately restored. This reductive load may impede recovery by suppression of cellular respiration and other cell and organ functions.