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)

In order to examine the effects of platelet-activating factor (PAF) in complicated Plasmodium falciparum infections, plasma concentrations of lyso-PAF, stable metabolite and principal precursor of PAF, were measured in 25 Vietnamese adults with severe malaria. The concentration of PAF in the cerebrospinal fluid (CSF) was determined in a sub-group of 23 comatose patients and, together with that of lyso-PAF, in the plasma of 20 patients on recovery of consciousness. The concentration of lyso-PAF in the plasma was depressed on admission to hospital (median [range]; 21 [8-143] vs. 293 [215-410] ng/ml in 10 controls; P < 0.001). There was, however, no change in plasma activity of acetylhydrolase which converts PAF to lyso-PAF (P > 0.01 vs. controls) while simultaneous reduction in the concentration of lipoproteins associated with lyso-PAF were less than those of lyso-PAF per se in the plasma. The plasma concentration of lyso-PAF on admission was associated with parasitaemia and the concentration of serum triglycerides (rs = -0.42, P = 0.04 in each case), the latter being consistent with hepatic effects of PAF reported in previous studies. CSF concentrations of PAF on admission were low (2.3 [0.5-7.7] vs. 0.9 [0-2.5] ng/ml after recovery, P < 0.01) compared with values reported previously in bacterial meningitis. Plasma concentrations of lyso-PAF after recovery lay between admission and control values. While increased availability of PAF may reflect parasite burden and may modulate liver-mediated metabolic disturbances such as hypoglycaemia and lactic acidosis, the role of PAF in cerebral malaria is uncertain.
 ...
PMID:The metabolism of platelet-activating factor in severe and cerebral malaria. 858 36

1 Dichloroacetate (DCA) is a promising treatment for lactic acidosis complicating severe malaria. The pharmacokinetics, pharmacodynamics and toxicity of dichloroacetate were evaluated in 11 patients with severe malaria, and their lactate responses compared with nine control patients in an open-label prospective study. 2 Intravenous DCA (46 mg kg-1 infused in 30 min) or saline placebo was given on admission to the study, and 12 h later, as an adjunct to standard quinine treatment. 3 An open one-compartment model with the following parameters described the pharmacokinetics of DCA after one dose (mean [s.d.]): V = 0.44(0.2) 1 kg-1; CL = 0.13 [0.027] 1 h-1 kg-1; Cmax = 106[28] mg1-1; t1/2 = 3.4(2.2) h. After two doses of DCA (n = 9) the pharmacokinetic parameters were similar to those after the first dose. 4 DCA decreased venous plasma lactate concentrations by 42% of baseline values 8 h after admission, normalized arterial pH from a mean(s.d.) of 7.367(0.063) to 7.39(0.1), and decreased the calculated base deficit from 9.2(7.3) mEq 1-1 to 6.4(10.4) mEq 1-1. In control patients lactate concentrations fell by approximately 14% of baseline concentrations (P < 0.02 compared with DCA recipients). Venous lactate concentrations fell a further 16% from baseline values after the second dose of DCA but this change was not significantly different from controls. There was no electrocardiographic or other evidence of toxicity associated with DCA. 5 These data suggest that a single intravenous infusion of DCA rapidly reduces hyperlactataemia in patients severely ill with malaria, and that DCA should be evaluated further as an adjunct to conventional antimalarial and supportive measures for such patients with lactic acidosis.
 ...
PMID:The disposition and effects of two doses of dichloroacetate in adults with severe falciparum malaria. 882 90

Falciparum malaria remains a major killer in developing countries, particularly for African children. The sequestration of parasitized erythrocytes in the deep microvasculature is mostly mediated by their cytoadherence to activated endothelium. Proinflammatory cytokines and particularly tumor necrosis factor contribute to severe disease but the pathophysiology of coma remains poorly understood. In young children, features of severe malaria include severe anemia, hypoglycemia and cerebral malaria. Half of the children with neurological impairment actually have raised intracranial pressure, and seizures are extremely common. Clinical respiratory distress usually reflects severe lactic acidosis. In non immune adults, pictures of severe sepsis with shock, acute renal failure and respiratory distress syndrome are common and often associated with bacterial coinfection. Although chemotherapy of malaria is challenged by the continuing evolution of antimalarial resistance, quinine remains the first-line drug for severe disease. The optimization of symptomatic management of severe malaria remains a major concern in developing countries.
 ...
PMID:[Severe malaria]. 978 Oct 74

Beriberi or thiamine deficiency is common in countries where malaria is endemic. The hypotheses that subclinical thiamine deficiency complicates malaria and may be associated with lactic acidosis and coma were investigated in a prospective study conducted in Kanchanaburi, Thailand. 77 consecutive patients who presented to Paholpolpayuhasena Hospital between May and July 1992 with malaria or other febrile illnesses and 50 healthy relatives and volunteers were enrolled. The activation coefficient for transketolase activity in erythrocytes was used to measure thiamine deficiency. The mean Box-Cox transformed coefficients were 0.166 among cases with severe malaria (n = 23), 0.145 in cases with uncomplicated malaria (n = 54), 0.138 in healthy volunteers (n = 27), 0.137 in febrile controls (n = 10), and 0.122 in healthy relatives of patients (n = 13). 12 patients (52%) with severe malaria and 10 (19%) of those with uncomplicated malaria had coefficients above the normal range. Thiamine deficiency occurred in significantly more patients with cerebral malaria than in those with uncomplicated malaria (odds ratio, 4.8; 95% confidence interval, 1.68-13.8). The 12 patients who died from severe malaria had higher coefficient values than the 115 patients and controls who survived. Finally, the 15 patients with lactic acidosis had significantly higher coefficient values than those without this complication. A study of thiamine administration to patients with cerebral malaria is recommended to allow distinctions between the findings recorded in this study and the possibility of a causal link.
 ...
PMID:Thiamine deficiency and malaria in adults from southeast Asia. 1002 83

Severe anemia is a major cause of death in falciparum malaria. Blood transfusion increases survival in humans and in animal models of this disease. Because of logistic constraints and viral contamination of the blood supply, transfusions are frequently not practical in endemic regions. Modified hemoglobin is an effective O2 carrier in hemorrhagic shock. It is free of infectious contamination, may not require refrigeration, and because of its nitric oxide scavenging and small size, may have pharmacologic benefits in malaria. The effects of transfusions of modified hemoglobin in rats with high-grade parasitemia were evaluated. Modified hemoglobin decreased lactic acidosis and corrected anemia as well as transfusions with red blood cells; these findings may correlate with improved survival and suggest a possible proerythropoietic effect. Further study of this novel therapy is warranted.
 ...
PMID:Decreased lactic acidosis and anemia after transfusion of o-raffinose cross-linked and polymerized hemoglobin in severe murine malaria. 1007 60

Children with severe malaria often present with lactic acidosis and hypoglycemia. Although both complications independently predict mortality, mechanisms underlying their development are poorly understood. To study these metabolic derangements we sequentially allocated 21 children with falciparum malaria and capillary lactate concentrations of 5 mmol/L or more to receive either quinine or artesunate as antimalarial therapy, and dichloroacetate or saline placebo for lactic acidosis. We then administered a primed infusion (90 min) of L-[3-13C1]sodium lactate and D-[6,6-D2]glucose to determine the kinetics of these substrates. The mean (SD) glucose disposal rate in all patients was 56 (16) micromol/kg x min, and the geometric mean (range) lactate disposal rate was 100 (66-177) micromol/kg x min. Glucose and lactate disposal rates were positively correlated (r = 0.62; P = 0.005). Artesunate was associated with faster parasite clearance, lower insulin/glucose ratios, and higher glucose disposal rates than quinine. Lactate disposal was positively correlated with plasma lactate concentrations (r = 0.66; P = 0.002) and time to recovery from coma (r = 0.82; P < 0.001; n = 15). Basal lactate disposal rates increased with dichloroacetate treatment. Elevated glucose turnover in severe malaria mainly results from enhanced anaerobic glycolysis. Quinine differs from artesunate in its effects on glucose kinetics. Increased lactate production is the most important determinant of lactic acidosis.
 ...
PMID:Glucose and lactate kinetics in children with severe malaria. 1077 Jan 99

Cerebral malaria is a rapidly progressive potentially fatal complication of Plasmodium falciparum infection. It is characterized by unarousable and persistent coma along with symmetrical motor signs. Children, pregnant women and non-immune adults are more susceptible to have cerebral malaria. Several clinical, histopathological and laboratory studies have suggested that cytoadherence of parasitized erythrocytes (mechanical hypothesis), and neuronal injury by malarial toxin and excessive cytokine (e.g. tissue necrosis factor-alpha) production (cytotoxic hypothesis) are possible pathogenic mechanisms. Several associated systemic complications like hypoglycemia, hypovolemia, hyperpyrexia, renal failure, bleeding disorders, anemia, lactic acidosis and pulmonary oedema may contribute in the pathogenesis of coma, and are responsible for high mortality. The meticulous supportive care along with intravenous administration of antimalarial drugs are corner-stone of the treatment. Quinine is currently, drug of choice. Artimisinin derivatives are equally effective and can be used by intramuscular route. In severe cases exchange blood transfusion may be an effective alternative. Corticosteroids has no place in the management of cerebral malaria. The occurrence of convulsions are common in children, these can be prevented with the use of single intramuscular administration of phenobarbitone. Despite advances in the management mortality and morbidity have not changed much. A large number of surviving patients are left with permanent neurological sequelae. There is a need to search for effective malaria prevention and interventional strategies to avert high mortality and morbidity associated with cerebral malaria.
 ...
PMID:Cerebral malaria. 1184 24

The Plasmodium berghei-infected mouse model is a well-recognized model for human cerebral malaria. Mice infected with P. berghei exhibit (i) metabolic acidosis (pH < 7.3) associated with elevated plasma lactate concentrations, (ii) significant (P < 0.05) vascular leakage in their lungs, hearts, kidneys, and brains, (ii) significantly (P < 0.05) higher cell and serum glutamate concentrations, and (iv) significantly (P < 0.05) lower mean arterial blood pressures. Because these complications are similar to those of septic shock, the simplest interpretation of these findings is that the mice develop shock brought on by the P. berghei infection. To determine whether the immune system and specifically CD8(+) T cells mediate the key features of shock during P. berghei malaria, we depleted CD8(+) T cells by monoclonal antibody (mAb) treatment and assessed the complications of malarial shock. P. berghei-infected mice depleted of CD8(+) T cells by mAb treatment had significantly reduced vascular leakage in their hearts, brains, lungs, and kidneys compared with infected controls treated with rat immunoglobulin G. CD8-depleted mice were significantly (P < 0.05) protected from lactic acidosis, glutamate buildup, and diminished HCO(3)(-) levels. Although the blood pressure decreased in anti-CD8 mAb-treated mice infected with P. berghei, the cardiac output, as assessed by echocardiography, was similar to that of uninfected control mice. Collectively, our results indicate that (i) pathogenesis similar to septic shock occurs during experimental P. berghei malaria, (ii) respiratory distress with lactic acidosis occurs during P. berghei malaria, and (iii) most components of circulatory shock are ameliorated by depletion of CD8(+) T cells.
 ...
PMID:CD8(+)-T-cell depletion ameliorates circulatory shock in Plasmodium berghei-infected mice. 1170 6

Hypoglycaemia and lactic acidosis are potentially life-threatening, poorly understood sequelae of Plasmodium falciparum infections. We investigated relationships between clinical status, treatment, and glucose and lactate kinetics during management of falciparum malaria in 14 Vietnamese adults. Nine had severe malaria, of whom 4 were administered quinine (Group 1a) and 5 artesunate (Group 1b). Five uncomplicated cases received artesunate (Group 2). Glucose and lactate turnover were studied on 3 occasions: (i) immediately after initial antimalarial treatment, (ii) at parasite clearance a median of 3 days later, and (iii) at discharge from hospital a median of 9 days post-admission. Steady-state glucose and lactate kinetics were derived from plasma isotopic enrichment during a primed-continuous infusion of D-[6,6-D2]glucose and a parallel infusion of L-[1-13C]lactate. Group 1a patients had the lowest plasma glucose concentrations in the admission study (median [range] 3.9 [3.6-5.1] vs 6.3 [4.9-7.1] and 4.5 [4.3-5.5] mmol/L in Groups 1b and 2 respectively; P < 0.05 vs Group 1b), but glucose production rates and serum insulin concentrations that were similar to those in the other groups (P > 0.17). This was also the case at parasite clearance and suggested an inappropriate beta cell response. Group 1a patients had the highest admission lactate production (60 [36-77] vs 26 [21-47] and 22 [4-31] mumol/kg.min in Group 1b and 2 respectively; P < 0.05 vs Group 2). Amongst the 9 severe cases, there was an inverse association between plasma glucose and lactate production at admission and parasite clearance (P < 0.05), but no correlation between admission lactate production and serum bicarbonate (P = 0.73). The present data confirm previous studies showing that quinine depresses plasma glucose through stimulation of insulin secretion. It is hypothesized that the low plasma glucose activates Na+,K(+)-ATPase through increased plasma catecholamine concentrations, leading to accelerated glycolysis and increased lactate production in well-oxygenated tissues. In some severely ill patients with falciparum malaria, a raised plasma lactate on its own may, therefore, be an unreliable index of a developing acidosis.
 ...
PMID:Glucose and lactate turnover in adults with falciparum malaria: effect of complications and antimalarial therapy. 1249 78

The authors conducted a randomized, double-blind, placebo-controlled trial of intravenous dichloroacetate (DCA) for the purpose of treating lactic acidosis in 124 West African children with severe Plasmodium falciparum malaria. Lactic acidosis independently predicts mortality in severe malaria, and DCA stimulates the oxidative removal of lactate in vivo. A single infusion of 50 mg/kg DCA was well tolerated. When administered at the same time as a dose of intravenous quinine, DCA significantly increased the initial rate and magnitude of fall in blood lactate levels and did not interfere with the plasma kinetics of quinine. The authors developed a novel population pharmacokinetic-pharmacodynamic indirect-response model for DCA that incorporated characteristics associated with disease reversal. The model describes the complex relationships among antimalarial treatment procedures, plasma DCA concentrations, and the drug's lactate-lowering effect. DCA significantly reduces the concentration of blood lactate, an independent predictor of mortality in malaria. Its prospective evaluation in affecting mortality in this disorder appears warranted.
 ...
PMID:Population kinetics, efficacy, and safety of dichloroacetate for lactic acidosis due to severe malaria in children. 1272 59


<< Previous 1 2 3 4 Next >>