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

The virulence of Plasmodia depends partly on the strain of parasite and partly on the host. In this study, Plasmodium berghei N/13/1A/4/203 caused the death of mice, whereas Plasmodium chabaudi chabaudi AS was not lethal. Current opinion is that nitric oxide (NO) and other reactive nitrogen intermediates (RNI) are produced in several host organs during malaria to resist infection or produce tissue damage. NO and RNI production in blood or plasma, brain, liver and spleen in MF1 mice was investigated during P. berghei and P. c. chabaudi infection, in order to help determine whether changes in NO production are beneficial or detrimental to the host in vivo. NO production was measured both directly and indirectly as nitrites and nitrates, to represent RNI. No changes in blood NO were detected in P. berghei infected mice, but increases were observed in brain, liver and spleen. In P. c. chabaudi infected mice, rises in NO concentration were observed in blood and spleen, whereas a decline in liver NO was seen, but there were no changes in brain. Liver contained the highest concentration of RNI, but increasing concentrations were seen in both plasma and spleen in both P. berghei and P. c. chabaudi infected mice. These results show that NO and RNI production alters during murine malaria. The changes depend upon the tissue, the day of infection, the degree of parasitaemia, the strain of Plasmodia and the method of measuring NO biosynthesis. Lethal P. berghei induced NO production in the mid and late stages of infection in mice when parasitaemia was high, whereas in nonlethal P. c. chabaudi infection, NO production was increased in the early and late stages when parasitaemia was low. These data are consistent with a role for NO in the protection of the MF1 mouse against Plasmodia. Failure to clear the parasite is associated with evidence of increased NO production in brain and liver, which may contribute to the pathology of malaria, but this hypothesis requires confirmation from other experimental approaches.
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PMID:Nitric oxide and reactive nitrogen intermediates during lethal and nonlethal strains of murine malaria. 1158 78

As part of our studies on the nitric oxide-related pathology of cerebral malaria, we show that the antioxidative enzyme glutathione reductase (GR) is inactivated by peroxynitrite, with GR from the malarial parasite Plasmodium falciparum being more sensitive than human GR. The crystal structure of modified human GR at 1.9-A resolution provides the first picture of protein inactivation by peroxynitrite and reveals that this is due to the exclusive nitration of 2 Tyr residues (residues 106 and 114) at the glutathione disulfide-binding site. The selective nitration explains the impairment of binding the peptide substrate and thus the nearly 1000-fold decrease in catalytic efficiency (k(cat)/K(m)) of glutathione reductase observed at physiologic pH. By oxidizing the catalytic dithiol to a disulfide, peroxynitrite itself can act as a substrate of unmodified and bisnitrated P. falciparum glutathione reductase.
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PMID:Crystal structure of the antioxidant enzyme glutathione reductase inactivated by peroxynitrite. 1170 98

The role of the spleen during Plasmodium falciparum malaria in humans is unclear. In Thailand, malaria transmission is low and splenomegaly is rarer than in high transmission areas. We compared the prevalence of splenomegaly between 52 cerebral malaria patients and 191 patients without complications despite a high parasite biomass. We also measured concentrations of reactive nitrogen intermediates (RNIs) in a fraction of these cases recruited in 1998 (24 cerebral malaria and 56 controls). Splenomegaly was significantly associated with cerebral malaria (adjusted odds ratio = 2.07 [95% confidence interval = 1-4.2]; P = 0.048). There was a linear trend for this association (P = 0.0003). After adjusting for potential confounders, concentrations of RNIs were significantly lower in the presence of splenomegaly (P = 0.01). These results suggest that in humans, as in animal models, the spleen may be involved in the pathogenesis of cerebral malaria. The relationship between RNI concentrations and the spleen suggest that nitric oxide may have a regulating role in the complex physiology of the spleen during malaria.
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PMID:Association of splenomegaly with cerebral malaria and decreased concentrations of reactive nitrogen intermediates in Thailand. 1171 28

Nitric oxide (NO) possesses antiparasitic effects on both Protozoa and Metazoa in vertebrate definitive and intermediate hosts. Inducible NO limits parasite development also in Rhodnius prolixus and Anopheles stephensi, the natural vectors of human trypanosomiasis and malaria respectively, and in the snail Biomphalaria glabrata, a natural invertebrate intermediate host of human schistosomiasis. Therefore, NO limits Trypanosoma, Plasmodium, and Schistosoma development at all stages of the parasite life cycle.
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PMID:Nitric oxide limits parasite development in vectors and in invertebrate intermediate hosts. 1204 94

Severe malarial anaemia (SA) is a major complication of malaria and an important cause of child mortality and morbidity. However, the pathogenesis behind SA is poorly understood. Nitric oxide (NO) is known to play a protective role against clinical malaria but is also suggested to have a pathogenic role in cerebral malaria (CM). Erythrophagocytosis by splenic macrophages has been implicated in the pathogenesis of SA. In this study, plasma levels of NO, neopterin, haptoglobin and C-reactive protein (CRP) were measured in paediatric patients with CM, n=77, SA (n=28) and uncomplicated malaria (UM n=53). Haptoglobin levels were significantly lower in SA (median (interquartile range) 25 (17-59) mg/l) than in both CM and UM (40 (24-80) mg/l and 110 (60-160) mg/l, respectively, P<0.001). In contrast, NO levels were higher in SA (38 (28-51) micromol/l) than in CM and UM (21 (15-32) micromol/l and 10.3 (5.6-17) micromol/l, respectively, P<0.001). A significant negative correlation between haptoglobin and NO was seen in the SA group. No such correlation was observed within the UM or CM groups. No significant differences in neopterin levels were observed between any of the three groups, neither was there any correlation between parasitaemias and neopterin levels. The low haptoglobin and high levels of NO in this SA group may contribute to haemolysis. Taken together our results support the hypothesis that immune-mediated erythrocyte destruction is involved in the pathogenesis of malarial anaemia.
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PMID:Elevated levels of nitric oxide and low levels of haptoglobin are associated with severe malarial anaemia in African children. 1208 54

Thirty two patients of malaria (15, 11 & 6) having P. vivax, uncomplicated and complicated P. falciparum malaria respectively, and 10 healthy controls were subjected to full clinical and laboratory examinations as well as estimation of plasma levels of tumor necrosis factor (TNF), interleukin-6 (IL-6) and nitric oxide (NO). The main clinical presentations were fever, pallor, jaundice, splenomegaly and anaemia which were more pronounced in patients with complicated falciparum malaria. Light coma (50%), convulsions (33.3%), severe anaemia (66.6%). severe hypoglycemia (66.6%) and increased blood lactate levels (50%) were detected in patients with complicated falciparum malaria. The results showed significant elevation of plasma levels of TNF, IL-6 and NO in all malaria patients as compared to the controls. The levels were significantly higher in patients with complicated falciparum malaria than in the other patient groups. The TNF, IL-6 and NO had an effective role in pathogenesis of malaria and their levels in can be a useful diagnostic markers for malaria and severity.
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PMID:Correlation of plasma levels of tumor necrosis factor, interleukin-6 and nitric oxide with the severity of human malaria. 1221 30

Interleukin-12 (IL-12) is an important regulatory cytokine in infection and immunity. Administration of IL-12 may reduce complications of severe malaria in rodents. Polymorphisms in IL12B, the gene encoding the IL-12 p40 subunit, influence the secretion of IL-12 and susceptibility to Type 1 diabetes. We therefore investigated whether IL12B polymorphisms may affect the outcome of severe malaria. Homozygosity for a polymorphism in the IL12B promoter was associated with increased mortality in Tanzanian children having cerebral malaria but not in Kenyan children with severe malaria. Furthermore, homozygotes for the IL12B promotor polymorphism had decreased production of nitric oxide, which is in part regulated by IL-12 activity. These studies suggest that IL12B polymorphisms, via regulation of IL-12 production, may influence the outcome of malaria infection in at least one African population.
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PMID:A promoter polymorphism in the gene encoding interleukin-12 p40 (IL12B) is associated with mortality from cerebral malaria and with reduced nitric oxide production. 1242 23

In this study, we investigated the role of nitric oxide metabolism and lipid peroxidation in patients with P. vivax malaria. The levels of nitrite and nitrate were analyzed using a procedure based on the Griess reaction and malondialdehyde levels which index of lipid peroxidation was determined by thiobarbituric acid reaction. The levels of nitrite/nitrate and malondialdehyde in patients were higher than controls and found to be statistically significant (p < 0.001). We performed this study to determine whether nitric oxide and lipid peroxidation is produced during blood-stage P. vivax malaria. This present study shows that lipid peroxidation occurs in P. vivax malaria. The levels of nitric oxide are associated with lipid peroxidation in this disease.
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PMID:The role of nitric oxide and lipid peroxidation in patients with Plasmodium vivax malaria. 1251 54

To assess the hypothesis that nitric oxide is critical in the pathogenesis of cerebral malaria, we analysed genetic variation in the proximal promoter region of NOS2A, the gene encoding inducible nitric oxide synthase. Sequencing 72 Gambian chromosomes revealed 11 single nucleotide polymorphisms in 2.5 kB (theta=8.6 x 10(-4)). Genotyping 104 nuclear families identified six common haplotypes. A single haplotype, uniquely defined by the NOS2A-1659T allele, was associated with cerebral malaria by a transmission disequilibrium test of 334 affected children and their parents (P=0.02). An independent case-control study of 505 different children from the same population replicated the allelic association with cerebral malaria (odds ratio: 1.31, P=0.04). Taken together these data indicate a weak but significant association of the NOS2A locus with susceptibility to cerebral malaria. Despite high linkage disequilibrium across the region studied, this association would not have been detected without the initial construction of a dense marker set for haplotype tagging.
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PMID:Nucleotide and haplotypic diversity of the NOS2A promoter region and its relationship to cerebral malaria. 1255 17

One hundred and five patients with Plasmodium falciparum were included, forty-three with cerebral malaria and sixty-two without cerebral manifestations. The main clinical presentations in cerebral malaria patients were fever (76.4%), pallor (72%), splenomegaly (60.5%), deep coma (39.5%), jaundice (18.6%), pulmonary oedema (13.9%), subconjunctival haemorrhage (13.9%), severe anemia (Hb<5mg/l) (53.5%), hypoglycemia (glucose<40mg/dl) (67.4%) and haemoglobinuria (6.9%) while in non cerebral malaria patients the clinical presentations were fever (83.8%), pallor (67.7%), splenomegaly (66%), jaundice (9.7%), severe anemia (Hb<5gm/dl) (51.6%) and hypoglycemia (glucose<40mg/dl) (3.2%). Nine patients from cerebral malaria group died after admission. Serum level of nitric oxide (nitrite plus nitrate) were assayed for all patients, serum level of nitric oxide were highly significant in patients with cerebral malaria than those without (34.6 +/- 2.3n. mol/ml VS 12.9 +/- 1.3n. mol/ml; P<0.01). In cerebral malaria, nitric oxide levels were highly elevated in patients with deeper coma than those with lighter coma (48.2 +/- 3.1n. mol/ml VS 24.4 +/- 1.3n. mol/ml; P<0.001) and also higher among patients with longer duration of coma (>72 hours) than among patients with shorter duration of coma (<72 hours) (54.5 +/- 2.8 n. mol/ml V.S. 23.6 +/- 3.1n. mol/ml; P<0.001). Also, nitric oxide levels were correlated with clinical outcome, fatal cases (9 patients) having significantly higher nitric oxide levels than survivors (56.2 +/- 3.1 n. mol/ml VS 32.5 +/- 1.3 n. mol/ml; P<0.001). Thus, higher levels of nitric oxide are associated with indices of disease severity and may predict outcome in-patients with cerebral malaria. These data are consistent with the hypothesis that nitric oxide is involved in the pathogenesis of cerebral malaria.
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PMID:Plasma levels of nitric oxide in association with severe Plasmodium falciparum in Yemen. 1256 1


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