Cyclic nucleotide levels in the perfused rat heart subjected to hypoxia.

Isolated rat hearts were subjected to hypoxic perfusion on a recirculating Langendorff apparatus. Following a 30-min-period of aerobic stabilization the hearts were perfused for 30 min with media equilibrated with 84% N2, 12%O2 and 4% CO2. At the end of the hypoxic period myocardial concentrations of cyclic AMP and cyclic GMP were determined by radioimmunoassay. Exposure to hypoxia resulted in a significant increase in cyclic AMP (p less than 0.01) and a decrease in cyclic GMP (p less than 0.05) as compared to hearts perfused for 60 min with media gassed with 96% O2. 4% CO2.     

Noradrenaline synthesis in human fetal heart.

The capacity of noradrenaline synthesis was investigated in 6 isolated human fetal hearts (13-23 gestational week). The mean rate of transforming perfused labelled tyrosine to noradrenaline in atrial, ventricular, and mediastinal tissue was 0.175, 0.168, and 0.108 mug/g tissue/h, respectively.     

Interaction between dehydroepiandrosterone, glucose-6-phosphate dehydrogenase, and cyclic adenosine-3',5'-monophosphate in neoplastic and normal human mammary tissue.

When total DHEA, G-6-PDH activity, and c-AMP were determined in human neoplastic mammary tissue and corresponding normal tissue the G-6-PDH activity in the former tissue greatly exceeded that found in normal tissue. On the other hand, a remarkable decrease of total DHEA and c-AMP could be detected in cancer tissue, hinting at the participation of DHEA in the intracellular regulation of G-6-PDH and c-AMP levels.     

Purification and properties of heat-resistant exotoxin produced by Macrophomina phaseolina (Tassi) Goid in culture.

A partially purified preparation of a water-soluble, heat-resistant, nonspecific exotoxin produced by a strain of Macrophomina phaseolina, isolated from Phaseolus mungo L. could reduce Cu++ ions and produced a red colour with 2,4-dinitrophenyl hydrazine reagent. It caused inhibition of seed germination, wilting of cult seedlings, stunted growth of young seedlings and loss of permeability of the cell membrane. Seedlings of P. mungo, grown in presence of the toxin showed a slight increase in the contents of protein and total RNA over control, but a significant increase in the specific activities of F-1, 6-BP aldolase and G-6-P isomerase.     

The effects of salicylate and aspirin on the activity of phosphorylase a in perfused hearts of rats

Summary Sodium salicylate and aspirin are known to have a glycogenolytic effect as judged by either the glycogen level or lactate production in perfused hearts of rats. In this work it was possible to demonstrate that phosphorylase a level was increased in the hearts subjected to the action of these drugs.     

Étude de l'activité in vitro de la glycogène phosphorylase de la Carpe (Cyprinus carpio L.)

Summary In this paper we give some values of glycogen phosphorylase activity of heart, red muscle and white muscle from the Carp. We show that in vitro optimum temperature is 25°C for the fish, and not 30°C as in Mammalians. We also made measurements with rat and tench liver, but it has been impossible, under the same experimental conditions, to observe normal release of inorganic phosphorus from G-1-P with carp liver.     

Cyclic nucleotide levels in the perfused rat heart subjected to hypoxia

Summary Isolated rat hearts were subjected to hypoxic perfusion on a recirculating Langendorff apparatus. Following a 30-min-period of aerobic stabilization the hearts were perfused for 30 min with media equilibrated with 84% N₂, 12% O₂ and 4% CO₂. At the end of the hypoxic period myocardial concentrations of cyclic AMP and cyclic GMP were determined by radioimmunoassay. Exposure to hypoxia resulted in a significant increase in cyclic AMP (p<0.01) and a decrease in cyclic GMP (p<0.05) as compared to hearts perfused for 60 min with media gassed with 96% O₂, 4% CO₂.Acknowledgment. We gratefully acknowledge the excellent technical assistance provided by Mrs Inger O. Boggs and Miss Patricia C. Hannigan. This work was supported in part by U. S. Public Health Service grant HL 14661 from the National Heart and Lung Institute, and by a grant from the Central Ohio Heart Chapter.     

Further studies on gel filtration of urinary substances.

Urine specimens from healthy children were concentrated and filtered through Sephadex G-100 and G-25. The eluate was recovered in fractions of 5 ml each. Total hexoses, galactose, total proteins and total uronic acids were determined on each fraction. Total hexoses and galactose were eluted in 6 distinct peaks. The uronic acid containing GAG were eluted in 4 small peaks on G-25 and 1 peak on G-100. This peak is eluted always with high amounts of galactose containing glycoproteins.     

Purification and properties of a heat-resistant exotoxin produced byMacrophomina phaseolina (Tassi) Goid in culture

Summary A partially purified preparation of a water-soluble, heat-resistant, nonspecific exotoxin produced by a strain ofMacrophomina phaseolina, isolated fromPhaseolus mungo L. could reduce Cu⁺⁺ ions and produced a red colour with 2,4-dinitrophenyl hydrazine reagent. It caused inhibition of seed germination, wilting of cut seedlings, stunted growth of young seedlings and loss of permeability of the cell membrane. Seedlings ofP. mungo, grown in presence of the toxin showed a slight increase in the contents of protein and total RNA over control, but a significant increase in the specific activities of F-1, 6-BP aldolase and G-6-P isomerase.     

The relations between G-6-PD deficiency,thalassemia and malaria. Further analysis of data from Sardinia and the Po Valley

Summary Discriminant analysis carried out on a set of environmental and sociocultural variables in the Sardinian population suggests that G-6-PD deficiency and thalassemia move along 2 dimensions partially independent of each other. Partial correlation analysis also suggests that malaria, by itself, may exert opposite effects on thalassemia and G-6-PD selection. The present results support the hypothesis that thalassemia may be the primary genetic factor selected by malaria, whereas G-6-PD selection may be a secondary adaptation phenomenon strongly dependent on other genetic and environmental variables.     

Glycoprotein biosynthesis in splenic cells. Purification of a microsomal galactosyl-transferase.

One part of the microsomal galactosyl-transferase activity of splenic cells of rats can by solubilized by the action of Triton X-100 and Tween 20. Its purification on a Sephadex G-200 column and by electrophoresis on a polyacrylamide gel leads to a solution of high specific enzymic activity.     

G-6PD loading of G-6PD-deficient erythrocytes

G-6PD-deficient erythrocytes were loaded during hypotonic hemolysis with G-6PD extracted from yeast. It was shown that enzyme was really trapped into red blood cells and remained functionally active.     

Further studies on gel filtration of urinary substances

Summary Urine specimens from healthy children were concentrated and filtered through Sephadex G-100 and G-25. The eluate was recovered in fractions of 5 ml each. Total hexoses, galactose, total proteins and total uronic acids were determined on each fraction. Total hexoses and galactose were eluted in 6 distinct peaks. The uronic acid containing GAG were eluted in 4 small peaks on G-25 and 1 peak on G-100. This peak is eluted always with high amounts of galactose containing glycoproteins.This work was partially supported by research grants from the CONICET, República Argentina.     

Phosphate mediated regulation of some of the enzymes of carbohydrate metabolism inNeurospora crassa

Summary The levels of FDP aldolase, isocitrate lyase, isocitrate dehydrogenase, malate dehydrogenase and glucose-6-P dehydrogenase were found to be rugulated by inorganic phosphate in the growth medium. The possible regulatory aspects have been discussed.     

G-6PD loading of G-6PD-deficient erythrocytes

Summary G-6PD-deficient erythrocytes were loaded during hypotonic hemolysis with G-6PD extracted from yeast. It was shown that enzyme was really trapped into red blood cells and remained functionally active.     

Leishmania infantum Nicolle, 1908, the agent of the autochthonous oriental sore. Apropos of the biochemical identification of 2 strains isolated in the eastern Pyrenees

Two strains of parasites isolated from cases of oriental sore in the Pyrénées-Orientales were identified by electrophoretic analysis of eight isoenzymes (PGM, PGI, G-6-PDH, 6-PGDH, IDH, MDH, ME and GOT). Both strains were identical with Leishmania infantum Nicolle, 1908, which normally causes visceral leishmaniasis. It is probable that, in the Mediterranean region, some cutaneous lesions observed within the area of visceral leishmaniasis are caused by this species rather than by Leishmania tropica (Wright, 1903) or Leishmania major (Yakimoff and Schokor, 1914) traditionally believed to be agents of cutaneous leishmaniasis in the Old World.     

Some characteristics of urokinase released in organ culture of human kidney.

Plasminogen activator produced in organ culture of human kidney, i.e. in the histotypical arrangement of the tissue, was partially purified by affinity chromatography on para-aminobenzamidine coupled to Sepharose by a 6-carbon spacer, followed by gel chromatography on Sephadex G-100. The molecular weight of 2 active peaks were 27,000 and 52,000 daltons respectively. It was inhibited by DFP and by IgG antiurokinase.     

Regulation of mitochondrial aconitase by phosphorylation in diabetic rat heart

Mitochondrial dysfunction and protein kinase C (PKC) activation are consistently found in diabetic cardiomyopathy but their relationship remains unclear. This study identified mitochondrial aconitase as a downstream target of PKC activation using immunoblotting and mass spectrometry, and then characterized phosphorylation-induced changes in its activity in hearts from type 1 diabetic rats. PKCβ₂ co-immunoprecipitated with phosphorylated aconitase from mitochondria isolated from diabetic hearts. Augmented phosphorylation of mitochondrial aconitase in diabetic hearts was found to be associated with an increase in its reverse activity (isocitrate to aconitate), while the rate of the forward activity was unchanged. Similar results were obtained on phosphorylation of mitochondrial aconitase by PKCβ₂ in vitro. These results demonstrate the regulation of mitochondrial aconitase activity by PKC-dependent phosphorylation. This may influence the activity of the tricarboxylic acid cycle, and contribute to impaired mitochondrial function and energy metabolism in diabetic hearts. Received 31 October 2008; received after revision 17 December 2008; accepted 2 January 2009     

Probing the penicillin sidechain selectivity of recombinant deacetoxycephalosporin C synthase

Deacetoxycephalosporin C synthase from Streptomyces clavuligerus catalyses the conversion of the five-membered penicillin ring to the unsaturated six-membered cephem ring of deacetoxycephalosporin C. The effects on enzyme activity of the penicillin substrate sidechain and various cofactors were investigated using a continuous spectrophotometric assay. The conversion of penicillin G to phenylacetyl-7-aminodeacetoxycephalo sporanic acid (G-7-ADCA) was confirmed, and further details of the reaction were elucidated. The conversion of ampicillin to cephalexin was faster than that of acetyl-6-APA to acetyl-7-ADCA kcat = 0.120 +/- 0.001 s(-1) versus 0.035 +/- 0.001 s(-1), but they had similar Km values: 4.86 +/- 0.12 and 3.28 +/- 0.26 mM, respectively. Amoxycillin and penicillin V were also converted at low levels. Conversion was not detected for penicillanate, 6-aminopenicillanate, carbenicillin, temocillin, ticarcillin or benzylpenicilloic acid, suggesting that the enzyme has a relatively strict selectivity for the sidechain of the penicillin substrate.     

Die Wirkung von Herzglykosiden und Kalzium auf den Kaliumtransport im Herzmuskel

Summary In isolated perfused guinea pig hearts, both strophanthin and calcium produced positive inotropic effects and contracture increasing with the concentration of the drugs. Strophanthin caused a net loss of potassium from the heart to the perfusing fluid whereas calcium did not interfer in the same way with potassium exchange. The data are consistent with the view that the positive inotropic effect of cardiac glycosides depends mainly on the increased intracellular calcium concentration, perhaps due to inhibition of the active potassium and sodium transport.