Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0024530 (malaria)
 44,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Circumsporozoite (CS) proteins, the major surface proteins of the sporozoites of the various malaria (Plasmodium) species, share a region of highly conserved sequence homology in common with sporozoite surface protein 2 (SSP2) and a group of proteins observed to specifically bind sulfated glycoconjugates. Recombinant P. yoelii CS protein was found to bind selectively to heparin-, fucoidan-, and dextran sulfate-Sepharose, but poorly to chondroitin sulfate A- or C-Sepharose. It also bound with lower affinity to a heparan sulfate biosynthesis-deficient mutant cell line compared with the wild-type. Likewise, P. berghei sporozoite invasion into hepatocytes was selectively inhibited by fucoidan, heparin, and dextran sulfate, and sporozoites bound specifically to sulfatide [galactosyl (3-SO4) beta 1-1 ceramide] coated surfaces. Sporozoite infectivity in mice was significantly inhibited by dextran sulfate 500,000 and fucoidan. Taken together, these data indicate that CS proteins bind selectively to certain sulfated glyconjugates and invasion of host hepatocytes by sporozoites, and sporozoite infectivity can be inhibited by such compounds.
 ...
PMID:Malaria sporozoites and circumsporozoite protein bind sulfated glycans: carbohydrate binding properties predicted from sequence homologies with other lectins. 823 19

A 24-year-old woman was infected with falciparum malaria during travel to Kenya, complicated by intravascular coagulation and pulmonary edema. She was successfully treated with anti-malarial drugs including chloroquine, quinine sulfate and pyrimethamine, with a combined regimen of heparin, antithrombin III and nafamostat mesilate for disseminated intravascular coagulation, and with methylprednisolone pulse therapy for pulmonary edema. The present case emphasizes the importance of early diagnosis and appropriate treatment in terms of falciparum malaria. This case, in particular, is believed to be worth reporting as overseas travel is increasing and yet anti-malarial drugs are not readily available to most physicians in Japan.
 ...
PMID:Falciparum malaria in an overseas traveler complicated by disseminated intravascular coagulation and pulmonary edema. 840 May 1

During feeding by infected mosquitoes, malaria sporozoites are injected into the host's bloodstream and enter hepatocytes within minutes. The remarkable target cell specificity of this parasite may be explained by the presence of receptors for the region II-plus of the circumsporozoite protein (CS) on the basolateral domain of the plasma membrane of hepatocytes. We have now identified these receptors as heparan sulfate proteoglycans (HSPG). The binding of CS to the receptors is abolished by heparitinase treatment, indicating that the recognition of region II-plus is via the glycosaminoglycan chains. We have purified and partially characterized the CS-binding HSPGs from HepG2 cells. They have a molecular weight of 400,000-700,000, are tightly associated with the plasma membrane, and are released from the cell surface by very mild trypsinization, a property which the CS receptors share with the syndecan family of proteoglycans.
 ...
PMID:Malaria circumsporozoite protein binds to heparan sulfate proteoglycans associated with the surface membrane of hepatocytes. 847 8

Sulfated proteoglycans have been shown to be involved in the binding of sporozoites of malaria parasites to hepatocytes. In this study, we have evaluated the effect of sulfated glycosaminoglycans on the invasion of erythrocytes by Plasmodium falciparum merozoites and cytoadherence of parasitized erythrocytes (PRBC) to endothelial cells. Invasion of erythrocytes by HB3EC-6 (an HB3 line selected for high binding to endothelial cells) was inhibited by dextran sulfate 500K, dextran sulfate 5K, sulfatides, fucoidan, and heparin but not by chondroitin sulfate A. With the exception of sulfatides, the invasion-inhibitory effect was not mediated by killing of parasites. Cytoadherence of HB3EC-6 to human microvascular endothelial cells (HMEC-1) and inhibited by these sulfated glycoconjugates. The highly sulfated dextran sulfate 500K had the highest inhibitory effect on both invasion and cytoadherence, whereas the positively charged protamine sulfate promoted cytoadherence. Because preincubation of PRBC with sulfated glycosaminoglycans and treatment of target cells with heparinase had no significant inhibition on cytoadherence, it is unlikely that sulfated glycoconjugates are used directly by endothelial cells as cytoadhesion receptors. In an vivo experiment, we found that the administration of dextran sulfate 500K to CBA/Ca mice infected with Plasmodium berghei ANKA reduced parasitemia and delayed the death associated with anemia. These observations suggest that sulfated polyanions inhibit the invasion of erythrocytes by merozoites and cytoadherence of PRBC to endothelial cells by increasing negative repulsive charge and sterically interfering with the ligand-receptor interaction after binding to target cells.
 ...
PMID:Sulfated polyanions inhibit invasion of erythrocytes by plasmodial merozoites and cytoadherence of endothelial cells to parasitized erythrocytes. 860 3

Women are particularly susceptible to malaria during first and second pregnancies, even though they may have developed immunity over years of residence in endemic areas. Plasmodium falciparum-infected red blood cells (IRBCs) were obtained from human placentas. These IRBCs bound to purified chondroitin sulfate A (CSA) but not to other extracellular matrix proteins or to other known IRBC receptors. IRBCs from nonpregnant donors did not bind to CSA. Placental IRBCs adhered to sections of fresh-frozen human placenta with an anatomic distribution similar to that of naturally infected placentas, and this adhesion was competitively inhibited by purified CSA. Thus, adhesion to CSA appears to select for a subpopulation of parasites that causes maternal malaria.
 ...
PMID:Adherence of Plasmodium falciparum to chondroitin sulfate A in the human placenta. 863 26

Red blood cell (RBC) adhesion to the vascular endothelium is increased in several pathologic conditions, including sickle cell disease and malaria. However, RBC interactions with components of the subendothelial matrix are not well-characterized. Under in vitro flow conditions of 1 dyne/cm2, washed RBCs bound to the purified adhesive molecules thrombospondin (TSP) and laminin. Sickle RBCs had the greatest adhesion of all tested RBCs. The adhesion of sickle RBCs to immobilized TSP was inhibited by the anionic polysaccharides high molecular weight (MW) dextran sulfate and chondroitin sulfate A, but not other anionic polysaccharides of similar structure and/or charge density. These data were consistent with the RBC adhesive molecule being a sulfated glycolipid. Therefore, TSP-binding lipids from normal and sickle RBCs were isolated and characterized. The TSP-binding lipid was purified by alkaline methanolysis, anion exchange chromatography and preparative thin layer chromatography (TLC). A homogeneous band on TLC was identified using a specific overlay TSP-binding assay. TSP binding to the purified lipid was stable to bass and neuraminidase treatment, labile to acid treatment, and was inhibited by high MW dextran sulfate, similar to that seen with intact RBCs binding to immobilized TSP under conditions of flow. In addition, soluble laminin bound to the purified RBC lipid. This acidic TSP- and laminin-binding lipid(s) isolated from both sickle and normal RBC membranes may contribute to erythrocyte interactions with the subendothelial matrix, hereby participating in the pathogenesis of vaso-occlusive diseases.
 ...
PMID:Increased adhesion of erythrocytes to components of the extracellular matrix: isolation and characterization of a red blood cell lipid that binds thrombospondin and laminin. 863 62

The association between cytoadherence of Plasmodium falciparum-infected erythrocytes and the severity of malaria has been evaluated. In this study, we investigate adherence to C32 melanoma cells, CD36, intracellular adhesion molecule-1 (ICAM-1), thrombospondin (TSP), E-selectin, vascular cell adhesion molecule-1 (VCAM-1), and chondroitin sulfate A (CSA) of 36 P. falciparum isolates from patients suffering from acute falciparum malaria. Adherence to purified adhesion molecules varied greatly among different parasite isolates. All isolates but one adhered to CD36, but none bound to E-selectin and VCAM-1 beyond control levels. Some P. falciparum isolates adhered to ICAM-1 and to CSA, a newly identified receptor for adherence. There was no correlation between in vitro binding to any one receptor and the patients' conditions. In addition, we investigated the characteristics of adherence to CSA and to C32 melanoma cells. Infected erythrocytes continued to adhere after trypsin digestion and soluble CSA inhibited adherence to C32 melanoma cells in a dose-dependent manner. The results imply a role for CSA in the natural infection of P. falciparum.
 ...
PMID:Cytoadherence characteristics of Plasmodium falciparum isolates from Thailand: evidence for chondroitin sulfate a as a cytoadherence receptor. 870 26

We studied 38 patients with acute renal failure (ARF) due to malaria over a 5-year period between 1990 and 1994 at the Institute of Urology and Transplantation. There were 30 males and 8 females who ranged in age from 13 to 75 years. Most were critically ill on presentation with blood urea levels between 116 and 587 mg% and serum creatinine concentrations between 3 and 30 mg%. Anemia accompanied by hyperbilirubinemia was a result of severe hemolysis. Antimalarial therapy consisted of quinine sulfate, chloroquine, or both. Of the 38 patients, 32 required hemodialysis and eventually recovered normal (n = 29) or near normal (n = 3) function. Six patients died.
 ...
PMID:Predictors of outcome in malarial renal failure. 887 97

The malaria circumsporozoite (CS) protein binds to glycosaminoglycan chains from heparan sulfate proteoglycans present on the basolateral surface of hepatocytes and hepatoma cells in vitro. When injected into mice, CS protein is rapidly cleared from the blood circulation by hepatocytes. The binding region for the HSPGs is the evolutionarily conserved region II-plus of the CS protein. Here we have asked whether the presence of glycosaminoglycans on the plasma membrane of target cells is required for sporozoite invasion in vitro. Two types of target cells were used: HepG2 cells, which are permissive for Plasmodium berghei sporozoite development into mature exoerythrocytic forms, and CHO cells, in which the intracellular development of the parasites is arrested early after penetration. The invasion of mutant CHO cells expressing undersulfated glycosaminoglycans or no glycosaminoglycans was only inhibited 41-49% or 24-32%, respectively, in comparison to invasion of CHO-K1 cells. Previous cleavage of HepG2 surface membrane glycosaminoglycans with heparinase or heparitinase had no significant inhibitory effect on subsequent P. berghei sporozoite invasion and EEF development in these cells, although the glycosaminoglycan lyase treatments removed over 80% of CS binding sites from the cell surface. These results suggest that although the presence of glycosaminoglycans on the target cell surface enhances sporozoite invasion, glycosaminoglycans are not required for sporozoite penetration or the development of exoerythrocytic forms in vitro.
 ...
PMID:Cell surface glycosaminoglycans are not obligatory for Plasmodium berghei sporozoite invasion in vitro. 892 11

Speed and selectivity of hepatocyte invasion by malaria sporozoites have suggested a receptor-mediated mechanism and the specific interaction of the circumsporozoite (CS) protein with liver-specific heparan sulfate proteoglycans (HSPGs) has been implicated in the targeting to the liver. Here we show that the CS protein interacts not only with cell surface heparan sulfate, but also with the low density lipoprotein receptor-related protein (LRP). Binding of 125I-CS protein to purified LRP occurs with a Kd of 4.9 nM and can be inhibited by the receptor-associated protein (RAP). Blockage of LRP by RAP or anti-LRP antibodies on heparan sulfate-deficient CHO cells results in more than 90% inhibition of binding and endocytosis of recombinant CS protein. Conversely, blockage or enzymatic removal of the cell surface heparan sulfate from LRP-deficient embryonic mouse fibroblasts yields the same degree of inhibition. Heparinase-pretreatment of LRP-deficient fibroblasts or blockage of LRP on heparan sulfate-deficient CHO cells by RAP, lactoferrin, or anti-LRP antibodies reduces Plasmodium berghei invasion by 60-70%. Parasite development in heparinase-pretreated HepG2 cells is inhibited by 65% when RAP is present during sporozoite invasion. These findings suggest that malaria sporozoites utilize the interaction of the CS protein with HSPGs and LRP as the major mechanism for host cell invasion.
 ...
PMID:Dual interaction of the malaria circumsporozoite protein with the low density lipoprotein receptor-related protein (LRP) and heparan sulfate proteoglycans. 892 Aug 59


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>