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Query: UMLS:C0024530 (malaria)
 44,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A serial study of coagulation activation and whole-blood viscosity was performed on 37 patients with local or systemic bacterial infection, malaria, or a viral infection. Thrombocytopenia, without consumption of coagulation factors, was the main feature of benign tertian malaria and viral infection, whereas in septicaemia and malignant tertian malaria it was associated with activation of coagulation and fibrinolysis. Patients with evidence of intravascular coagulation showed the highest levels of factor VIII related antigen which did not correlate with fibrinogen and probably reflected vascular endothelial cell damage rather than an acute-phase protein reaction. Hyperviscosity, which has been implicated in the pathogenesis of endotoxic shock and cerebral malaria, occurred in parallel with the acute-phase rise in plasma fibrinogen. There was, however, no evidence to implicate hyperviscosity as a major causative factor in the pathogenesis of septic shock or severe infective illness.
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PMID:Coagulation activation and hyperviscosity in infection. 47

A pathophysiologic study was made in 15 patients with acute renal failure due to falciparum malaria. Marked increase in plasma fibrinogen and elevation of serum fibrin degradation products were observed in all cases. The other coagulation parameters including prothrombin time, partial thromboplastin time, factor V and factor VIII were within the normal limits. Plasma hemoglobin was minimal. The blood viscosity was significantly increased. Blood volume study in 5 patients showed initial hypovolemia followed by hypervolemia and normovolemia. Decreased cortical renal blood flow was noted in renal hemodynamic study using 133Xe. Plasma renin activity was increased. Intravenous pyelography during the oliguric phase of renal failure revealed a poor nephrogram which increased in density at 24 and 48 h after the injection of the contrast material. The findings suggest the significance of reduction of renal blood flow in the pathogenesis of renal failure in human malaria. The roles of blood hyperviscosity and hypovolemia are emphasized.
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PMID:Renal failure in malaria: a pathophysiologic study. 86 56

Plasmodium falciparum infected erythrocytes containing mature trophozoites and schizonts sequester along venular endothelium and are not in the peripheral circulation of patients with malaria. Knobs appear on infected erythrocytes and are the points of attachment to endothelium. Sequestration may protect the parasite from splenic destruction and may play a role in the pathogenesis of cerebral malaria. Correlates of sequestration have been developed in vitro using cultured human endothelium and an amelanotic melanoma cell line. Knobless strains (K-) of P. falciparum fail to sequester in vivo and to bind to cells in vitro. We now present evidence that the receptor for cytoadherence is the glycoprotein, thrombospondin. Aotus monkey or human erythrocytes containing knobby (K+) but not Aotus erythrocytes containing knobless strains of P. falciparum bind to immobilized thrombospondin. Neither binds to the adhesive proteins laminin, fibronectin, factor VIII/von Willebrand factor or vitronectin. Both soluble thrombospondin and anti-thrombospondin antibodies inhibit binding of parasitized Aotus erythrocytes to immobilize thrombospondin and to melanoma cells which secrete thrombospondin.
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PMID:Thrombospondin binds falciparum malaria parasitized erythrocytes and may mediate cytoadherence. 241 70

Toward understanding the pathogenesis of vascular sequestration in falciparum malaria, we investigated binding of Plasmodium falciparum parasitized erythrocyte isolates to thrombospondin and other adhesive proteins. Blood samples with rings from 12 patients with falciparum malaria were cultured 30 hr until parasites were mature trophozoites and schizonts. All parasitized erythrocyte isolates bound to thrombospondin, but not to fibronectin, laminin, vitronectin, or factor VIII/von Willebrand factor. Parasitized erythrocyte binding varied among isolates, ranging from 192 to 6,725 per mm2, average 2,953. There was good correlation between trophozoite plus schizont % parasitemia and thrombospondin binding (r = 0.884, P less than 0.001). In two patients with stupor, 3,642 and 2,864 parasitized erythrocytes bound per mm2, in proportion to parasitemia, suggesting cerebral malaria is not due to increased binding affinity. These results indicate there is a conserved function among isolates from this geographic region, known to be antigenically diverse at the parasitized erythrocyte membrane surface. These results support the hypothesis that specific binding to an endothelial receptor, possibly involving thrombospondin, plays a role in vascular sequestration in falciparum malaria.
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PMID:Thrombospondin binding by parasitized erythrocyte isolates in falciparum malaria. 354 49

Different parameters of fibrinolytic systems like t-PA, PAI, D-dimer, and inhibitors of blood coagulation, i.e., protein C (PC), protein S(PS), and antithrombin III (AT-III), have been studied in cases of acute malaria due to Plasmodium falciparum and plasmodium vivax infection, and these patients were followed up. It was observed that the plasma PAI-1 was very high in cases of P. falciparum malaria infection as compared to normal controls and P. vivax infection. The changes in complicated cases of P. falciparum were remarkable as compared to uncomplicated ones. The PC, PS, and AT-III levels were also low in P. falciparum, particularly so in complicated cases, and were normal in P. vivax infection. The factor VIII R:Ag levels were invariably high in acute malaria. On follow-up of some of these cases the values came back to normal after the antiparasite treatment. The monocyte procoagulant activity was found to be significantly higher in P. falciparum infection as compared to that of P. vivax infection. All these findings therefore contribute towards the production of a hypercoagulable state in P. falciparum infection and partly explain the complications of P. falciparum infection like cerebral malaria.
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PMID:Fibrinolysis, inhibitors of blood coagulation, and monocyte derived coagulant activity in acute malaria. 898 Feb 57

Tyrosine sulfation is one of the most common post-translational modifications in secreted and transmembrane proteins and a key modulator of extracellular protein-protein interactions. Several proteins known to be tyrosine sulfated play important roles in physiological processes, and in some cases a direct link between protein function and tyrosine sulfation has been established. In blood coagulation, tyrosine sulfation of factor VIII is required for efficient binding of von Willebrand factor; in leukocyte adhesion, tyrosine sulfation of the P-selectin glycoprotein ligand-1 mediates high-affinity binding to P-selectin; and in leukocyte chemotaxis, tyrosine sulfation of chemokine receptors is required for optimal interaction with chemokine ligands. Furthermore, tyrosine sulfation has been implicated in several infectious diseases. In particular, tyrosine sulfation of the HIV-1 co-receptor CCR5 is required for viral entry into host cells and tyrosine sulfation of the Duffy antigen/receptor for chemokines is crucial for erythrocyte invasion by the malaria parasite plasmodium vivax. Despite increasing interest in tyrosine sulfation in recent years, the sulfoproteome still remains largely unexplored. To date, only a relatively small number of sulfotyrosine-containing peptides and proteins have been identified, and a specific role for tyrosine sulfation has not been established for most of these. Here, we provide an overview of the biology and enzymology of tyrosine sulfation and discuss recent developments in preparative and analytical methods that are central to sulfoproteome research.
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PMID:Toward a framework for sulfoproteomics: Synthesis and characterization of sulfotyrosine-containing peptides. 1768 Jul 2

Plasmodium falciparum infection results in adhesion of infected erythrocytes to blood vessel endothelium, and acute endothelial cell activation, together with sequestration of platelets and leucocytes. We have previously shown that patients with severe infection or fulminant cerebral malaria have significantly increased circulatory levels of the adhesive glycoprotein von Willebrand factor (VWF) and its propeptide, both of which are indices of endothelial cell activation. In this prospective study of patients from Ghana with severe (n = 20) and cerebral (n = 13) P. falciparum malaria, we demonstrate that increased plasma VWF antigen (VWF:Ag) level is associated with disproportionately increased VWF function. VWF collagen binding (VWF:CB) was significantly increased in patients with cerebral malaria and severe malaria (medians 7.6 and 7.0 IU/ml versus 1.9 IU/ml; p<0.005). This increased VWF:CB correlated with the presence of abnormal ultra-large VWF multimers in patient rather than control plasmas. Concomitant with the increase in VWF:Ag and VWF:CB was a significant persistent reduction in the activity of the VWF-specific cleaving protease ADAMTS13 (approximately 55% of normal; p<0.005). Mixing studies were performed using P. falciparum patient plasma and normal pooled plasma, in the presence or absence of exogenous recombinant ADAMTS13. These studies demonstrated that in malarial plasma, ADAMTS13 function was persistently inhibited in a time-dependent manner. Furthermore, this inhibitory effect was not associated with the presence of known inhibitors of ADAMTS13 enzymatic function (interleukin-6, free haemoglobin, factor VIII or thrombospondin-1). These novel findings suggest that severe P. falciparum infection is associated with acute endothelial cell activation, abnormal circulating ULVWF multimers, and a significant reduction in plasma ADAMTS13 function which is mediated at least in part by an unidentified inhibitor.
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PMID:Severe Plasmodium falciparum malaria is associated with circulating ultra-large von Willebrand multimers and ADAMTS13 inhibition. 1930 Apr 93