scholarly journals Isolation and characterization of the plasma membrane of human erythrocytes infected with the malarial parasite Plasmodium falciparum.

1983 ◽  
Vol 80 (4) ◽  
pp. 1087-1091 ◽  
Author(s):  
J. Gruenberg ◽  
I. W. Sherman
Keyword(s):  
Plasmodium Falciparum ◽  
Plasma Membrane ◽  
Human Erythrocytes ◽  
Malarial Parasite ◽  
Isolation And Characterization ◽  
Parasite Plasmodium ◽  
Parasite Plasmodium Falciparum

scholarly journals Polyamine levels and the activity of their biosynthetic enzymes in human erythrocytes infected with the malarial parasite, Plasmodium falciparum

1984 ◽  
Vol 222 (3) ◽  
pp. 815-819 ◽  
Author(s):  
Y G Assaraf ◽  
J Golenser ◽  
D T Spira ◽  
U Bachrach
Keyword(s):  
Plasmodium Falciparum ◽  
Human Erythrocytes ◽  
Malarial Parasite ◽  
Biosynthetic Enzymes ◽  
Irreversible Inhibitor ◽  
Trophozoite Stage ◽  
Polyamine Biosynthesis ◽  
Parasite Plasmodium ◽  
Parasite Plasmodium Falciparum ◽  
Polyamine Content

Human erythrocytes contain only trace amounts of polyamines and lack active polyamine biosynthetic enzymes. A remarkable increase in polyamine content, and in the activity of ornithine and S-adenosyl-L-methionine decarboxylases, is noted in synchronous cultures of the malarial parasite, Plasmodium falciparum. Polyamine biosynthesis reached peak values during the early trophozoite stage, whereas nucleic acid and protein synthesis occurred later in mature trophozoites. DL-alpha-Difluoromethylornithine, an irreversible inhibitor of ornithine decarboxylase, did not interfere with merozoite invasion and with ring-form development, but prevented the transformation of trophozoites to schizonts. Concomitantly, the synthesis of proteins and nucleic acids was significantly inhibited. These inhibitory effects could be readily reversed by the diamine putrescine. Macromolecular synthesis and schizogony were normal when 5-10 mM-DL-alpha-difluoromethylornithine and 0.1 mM-putrescine were added to the cultures simultaneously.

scholarly journals The effect of purified aminoaldehydes produced by polyamine oxidation on the development in vitro of Plasmodium falciparum in normal and glucose-6-phosphate-dehydrogenase-deficient erythrocytes

1986 ◽  
Vol 236 (1) ◽  
pp. 97-101 ◽  
Author(s):  
D M L Morgan ◽  
U Bachrach ◽  
Y G Assaraf ◽  
E Harari ◽  
J Golenser
Keyword(s):  
Plasmodium Falciparum ◽  
Lethal Effect ◽  
Human Erythrocytes ◽  
Malarial Parasite ◽  
Parasite Plasmodium ◽  
Parasite Plasmodium Falciparum ◽  
Development In Vitro ◽  
Glucose 6 Phosphate Dehydrogenase ◽  
Polyamine Oxidation

Purified aminoaldehydes produced by polyamine oxidation were toxic to the malarial parasite, Plasmodium falciparum, cultured in human erythrocytes. There was a profound effect on young ring forms, and, during maturation, parasites became more sensitive to the aldehydes. Oxidation of the aldehydes abolished the lethal effect. The plasmodia within glucose-6-phosphate-dehydrogenase (G6PD)-deficient erythrocytes were more sensitive to mono- and di-aldehydes than were parasites in normal erythrocytes. G6PD-deficient erythrocytes were also more sensitive to pretreatment with the dialdehyde produced by the oxidation of spermine. Pretreatment prevented further invasion by the parasites.

scholarly journals Effect of polyamine depletion on macromolecular synthesis of the malarial parasite, Plasmodium falciparum, cultured in human erythrocytes

1987 ◽  
Vol 242 (1) ◽  
pp. 221-226 ◽  
Author(s):  
Y G Assaraf ◽  
L Abu-Elheiga ◽  
D T Spira ◽  
H Desser ◽  
U Bachrach
Keyword(s):  
Amino Acids ◽  
Plasmodium Falciparum ◽  
Dna Synthesis ◽  
Rna Synthesis ◽  
Human Erythrocytes ◽  
Malarial Parasite ◽  
Macromolecular Synthesis ◽  
Irreversible Inhibitor ◽  
Parasite Plasmodium ◽  
Parasite Plasmodium Falciparum

DL-alpha-Difluoromethylornithine (DFMO), an irreversible inhibitor of ornithine decarboxylase, prevented the increases in putrescine and spermidine, but not in spermine, in human erythrocytes infected with the malarial parasite Plasmodium falciparum. The addition of putrescine to these polyamine-depleted cultures restored the normal concentrations of spermidine, whereas that of putrescine even exceeded that of the control cultures. DFMO also inhibited the incorporation of radioactive amino acids into the proteins of parasitized erythrocytes. Electrophoresis on polyacrylamide gels revealed that the synthesis of some proteins was completely blocked by DFMO, but the synthesis of others was not affected. DFMO also caused a partial inhibition of RNA synthesis, and DNA synthesis was completely blocked in polyamine-depleted parasitized erythrocytes. It has been suggested that putrescine and/or spermidine are required for the synthesis of certain proteins in parasitized erythrocytes and that at least one of those proteins is related to the synthesis of DNA of the malarial parasite. It appears that polyamines regulate the schizogony process of P. falciparum.

scholarly journals Differential Stimulation of the Na+/H+ Exchanger Determines Chloroquine Uptake in Plasmodium falciparum

1998 ◽  
Vol 140 (2) ◽  
pp. 335-345 ◽  
Author(s):  
Stefan Wünsch ◽  
Cecilia P. Sanchez ◽  
Michael Gekle ◽  
Lars Große-Wortmann ◽  
Jochen Wiesner ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Malarial Parasite ◽  
Physiological Data ◽  
Ph Measurements ◽  
Parasite Plasmodium ◽  
Parasite Plasmodium Falciparum ◽  
Transitory Phase ◽  
Identification And Characterization

Here we describe the identification and characterization of a physiological marker that is associated with the chloroquine-resistant (CQR) phenotype in the human malarial parasite Plasmodium falciparum. Single cell in vivo pH measurements revealed that CQR parasites consistently have an elevated cytoplasmic pH compared to that of chloroquine-sensitive (CQS) parasites because of a constitutively activated Na+/H+ exchanger (NHE). Together, biochemical and physiological data suggest that chloroquine activates the plasmodial NHE of CQS parasites, resulting in a transitory phase of rapid sodium/hydrogen ion exchange during which chloroquine is taken up by this protein. The constitutively stimulated NHE of CQR parasites are capable of little or no further activation by chloroquine. We propose that the inability of chloroquine to stimulate its own uptake through the constitutively activated NHE of resistant parasites constitutes a minimal and necessary event in the generation of the chloroquine-resistant phenotype.

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