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)

One of the major factors in the development of severe protein-energy malnutrition (PEM) is infection, such as diarrhea, upper respiratory infection, and malaria. Social and environmental factors include family size, access to land and occupation of parents, and exposure of rural populations to urban centers. Breast milk has been shown to play a role in the prevention of infections; however, the mother must be well-nourished to provide the optimum product. Traditional foods available to rural children in most developing countries are difficult to digest and low in energy and protein and inadequate nutritional education prevents the inclusion of good protein sources in children's diets. Severe PEM, called marasmus and kwashiorkor is indicated by wasting of muscles, absence of subcutaneous fat, wrinkled skin, thin and sparse hair, and weakness. The basic treatment for severe PEM is dietary. Treatment of kwashiorkor and marasmus is divided into 3 stages: 1) attending to acute problems, 2) restoring nutritional balance, and 3) ensuring nutritional rehabilitation. Care must be taken to ensure a minimum daily intake of 3-4 gm of protein and 120-150 Kcal of energy/kg of body weight. There must be, in addition, replacement of vitamin A, zinc, potassium, magnesium, and iron. An initial regimen which has been advocated is based on dry skim milk, sugar, and vegetable oil, divided into 6-12 feedings/day, which prevents vomiting. It is not necessary to remove lactose from the diet, and other animal protein sources such as meat and meat extracts are also well accepted. Soy and vegetable protein have been used successfully. In treating mild and moderate PEM it is important to ensure the intake of these food supplements by the child and to avoid a major substitution effect in the household diet. It is crucial for the physicians, nutritionists, public health workers, and educators to convince parents about the safety of using foods that are fed only to adults and older children. In addition nutritional and health education must not be restricted to the rehabilitation of the child but the prevention of nutritonal deterioration of the entire family and sometimes to the entire community.
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PMID:Infantile malnutrition in the tropics. 681 12

Episodic muscular weakness, commonly associated with alterations of serum potassium, is the cardinal feature of periodic paralysis. The combination of transient hyperkalaemia and rigors occurring during febrile episodes of malaria is suggested as the underlying cause which precipitated the muscular paralysis. Three patients with malaria who developed a similar paralysis during the paroxysms of fever are described to illustrate this.
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PMID:Periodic paralysis complicating malaria. 702

Renal function was assessed in 40 children during the acute illness and after recovery from falciparum malaria. Creatinine clearance was significantly lower during the acute illness than after recovery. Six of 18 children with impaired creatinine clearance (< 50 ml/min/1.73 m2) had evidence of acute tubular dysfunction. Hyponatraemia occurred in 12.5% during the acute phase. Fractional sodium excretion was raised in 27% during the acute illness and continuing sodium wastage occurred in 17% after recovery. Plasma potassium was significantly higher and fractional potassium excretion (FeK) significantly lower during the acute illness than after recovery. There was a positive correlation between FeNa and FeK both during and after recovery from the illness but they did not exactly mirror each other in every individual. Urine sodium:potassium ratios were similar during and after recovery from the illness and was related to FeNa. Fractional glucose excretion was zero. Mild proteinuria occurred in 40% during the acute illness but were not related to creatinine clearance, body temperature at presentation, or peripheral parasite density. Proteinuria was absent after recovery. Acute intrinsic renal impairment occurs during apparently 'uncomplicated' falciparum malaria in children.
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PMID:Renal function in acute falciparum malaria. 866 27

A novel solid-phase extraction and a robust high-performance liquid chromatographic (HPLC) separation procedure for artesunate and alpha- and beta-dihydroartemisinin, using post-column alkali decomposition and UV detection is described. Extraction was performed with Bond-Elut Phenyl solid-phase extraction cartridges and analysis by HPLC was carried out using a Waters Symmetry C8 5-microns 150 x 3.9 mm I.D. column. The mobile phase was 50% acetonitrile in 0.1 M acetate buffer (pH 4.8) delivered at a flow-rate of 0.7 ml/min. The column eluate was mixed with 1.2 M potassium hydroxide in 90% methanol delivered at 0.3 ml/min, in a 1-ml reaction coil at 69 degrees C, to form UV-absorbing chromophores which were detected at 290 nm. The recovery of all analytes was greater than 80%. There was no significant difference in the peak-area ratio of alpha- and beta-dihydroartemisinin in plasma. Preliminary pharmacokinetic data from six adult Vietnamese patients who received 120 mg of artesunate by intravenous injection for the treatment of acute falciparum malaria are presented. Despite limited data, the mean half-life of artesunate was approximately 3.5 min while that for dihydroartemisinin was 34 min. These data confirm the relatively rapid clearance of both artesunate and its principle active metabolite, dihydroartemisinin.
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PMID:Selective high-performance liquid chromatographic determination of artesunate and alpha- and beta-dihydroartemisinin in patients with falciparum malaria. 870 40

In order to get a better understanding in the mechanism by which tryptophan-N-formylated gramicidin (NFG) and gramicidin kill the malaria parasite Plasmodium falciparum in vitro, we studied the capacity of these peptides to change the potassium, as well as the sodium, composition of normal human erythrocytes, and their ability to cause cell lysis. It is shown that both peptides are able to induce potassium leakage from, and sodium flux into, erythrocytes in such a manner that it is most likely that they are able to form cation channels in the membrane of these cells. For both peptides, potassium efflux proceeds at a faster rate than sodium influx, but this difference is greater for NFG than for gramicidin. This explains the observation that gramicidin is more lytic than NFG is, even when comparing concentrations that show the same antimalarial activity. The finding that gramicidin is approximately 10 times more active than NFG in causing potassium efflux from normal erythrocytes, as well as in killing the malaria parasite, supports the hypothesis that peptide-induced parasite death is related to their capacity to induce potassium leakage from infected erythrocytes. Finally, the observation that erythrocytes are able to restore their normal ion contents after losing more than 50% of their potassium content by incubation with NFG or gramicidin, suggests that, in vivo, and upon treatment with drug concentrations that cause full inhibition of parasite growth, these cells would not be irreversibly damaged by action of the drugs.
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PMID:Effects of gramicidin and tryptophan-N-formylated gramicidin on the sodium and potassium content of human erythrocytes. 911 61

Carbon dioxide (CO2) is essential for the growth of intraerythrocytic malaria parasites to synthesize pyrimidine through CO2 fixation and to regulate intracellular pH. CO2 transport across the plasma membrane of erythrocytes is facilitated by carbonic anhydrase (CA). With the use of electron microscopy and CA-specific Hansson's stain, CA is found also in all the intraerythrocytic stages of Plasmodium falciparum. When CA inhibitors, including acetazolamide, potassium iodide, and sodium deoxycholate, were added to continuous culture of P. falciparum, they, particularly sodium deoxycholate, produced a marked reduction in parasitemia. These results explain the biochemical basis of some of the clinical conditions associated with malaria and strongly suggest that CA inhibitors have potential as a new class of antimalarials.
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PMID:The pivotal role of carbonic anhydrase in malaria infection. 948 77

The ionophore properties of cationomycin and monensin were studied on human erythrocytes by measuring Na+ influx by 23Na NMR and concomitant K+ efflux by potentiometry in the presence of increasing amounts of serum. Both ion currents (Na+ or K+) decreased linearly with the reciprocal of serum amount. The serum effects on ion currents were stronger with cationomycin than with monensin. Assuming this decreased transport activity was due to drug binding to serum proteins, a partition coefficient between the protein and the membrane phase was determined for each ionophore by using a novel model. This partition coefficient is about 30 times higher for cationomycin than for monensin; the same result was obtained with purified human serum albumin, indicating that albumin may be the major ionophore binding protein of serum. In parallel, we also measured IC50 for 50% in vitro growth inhibition of Plasmodium falciparum, the agent of malaria. In the presence of increasing serum concentrations, the antimalarial activity was decreased for both ionophores. Serum effect was less severe for monensin than for cationomycin, in agreement with the weaker interaction of monensin with proteins as shown from the partition coefficient values. A correlation was established between the ion transport currents (sodium and potassium) and the IC50 measured on P. falciparum in the presence of the various concentrations of serum. The relative value of the ion transport currents (expressed as percentage of control in absence of serum) can be indicative of the ionophore unbound fraction in the medium.
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PMID:Cationomycin and monensin partition between serum proteins and erythrocyte membrane: consequences for Na+ and K+ transport and antimalarial activities. 1006 60

Of 51 consecutive children with cerebral malaria, fever, convulsions, and drowsiness were the commonest presenting symptoms. Decerebrate and decorticate postures and absent cornea reflex were the commonest brain stem signs. Opening lumbar cerebrospinal (CSF) pressure was raised in all but one of 24 children in whom it was reliably measured [mean 15.2 +/- 5.7 mmHg, range 6-24]. Hyponatraemia occurred in 17 (33%). Acute renal failure was not uncommon; the combination of hypercreatininaemia (plasma creatinine > 100 mumol/L) and hyperkalaemia (plasma potassium > 6.0 mumol/L) was fatal in 5 out of 7 patients in whom it occurred. Disturbances of acid-base status were present in all 40 children in whom it was assessed on admission. Mortality rate was 16% (8 patients). Neurological deficits occurred in 7 (14%) of the survivors and included cortical blindness [3], aphasia [3], hypertonia [3], hearing loss [2], and dystonia [1]. In addition to the present measures aimed at reducing morbidity and morality in children with cerebral malaria, efforts should be directed at rapid assessment of renal function and prompt correction of such dysfunction if found.
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PMID:Clinical study of cerebral malaria in African children. 1089 20

The 13-residue dermaseptin S4 derivative K(4)S4(1-13)a (P) was previously shown to kill intraerythrocytic malaria parasites through the lysis of the host cells. In this study, we have sought peptides that will kill the parasite without lysing the erythrocyte. To produce such peptides, 26 compounds of variable structure and size were attached to the N terminus of P and screened for antiplasmodium and hemolytic activities in cultures of Plasmodium falciparum. Results from this screen indicated that increased hydrophobicity results in amplified antiplasmodium effect, irrespective of the linearity or bulkiness of the additive. However, increased hydrophobicity also was generally associated with increased hemolysis, with the exception of two derivatives: propionyl-P (C3-P) and isobutyryl-P (iC4-P). Both acyl-peptides were more effective than P, with 50% growth inhibition at 3.8, 4.3, and 7.7 microM, respectively. The antiparasitic effect was time dependent and totally irreversible, implying a cytotoxic effect. The peptides were also investigated in parallel for their ability to inhibit parasite growth and to induce hemolysis in infected and uninfected erythrocytes. Whereas the dose dependence of growth inhibition and hemolysis of infected cells overlapped when cells were treated with P, the acyl-peptides exerted 50% growth inhibition at concentrations that did not cause hemolysis. Noticeably, the acyl derivatives, but not P, were able to dissipate the parasite plasma membrane potential and cause depletion of intraparasite potassium under nonhemolytic conditions. These results clearly demonstrate that the acyl-peptides can affect parasite viability in a manner that is dissociated from lysis of the host cell. Overall, the data indicate the potential usefulness of this strategy for development of selective peptides as investigative tools and eventually as antimalarial agents.
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PMID:In vitro antiplasmodium effects of dermaseptin S4 derivatives. 1189 90

The alpha thalassaemias are the commonest known human genetic disorders. Although they have almost certainly risen to their current frequencies through natural selection by malaria, the precise mechanism of malaria protection remains unknown. We have investigated the characteristics of red blood cells (RBCs) from individuals heterozygous for alpha(0)thalassaemia (-/alphaalpha) from a range of perspectives. On the basis of the hypothesis that defects in membrane transport could be relevant to the mechanism of malaria protection, we investigated sodium and potassium transport and the activity of the Plamodium falciparum-induced choline channel but found no significant differences in -/alphaalpha RBCs. Using flow cytometry, we found that thalassaemic P. falciparum-infected RBCs (IRBCs) bound 44% more antibody from immune plasma than control IRBCs. This excess binding was abrogated by predigestion of IRBCs with trypsin but was not directed at the variant surface molecule PfEMP1. Furthermore, we found no evidence for altered cytoadhesion of alpha-thalassaemic IRBCs to the endothelial receptors intercellular adhesion molecule-1 (ICAM-1), CD36 or thrombospondin. We hypothesize that altered red-cell membrane band 3 protein may be a target for enhanced antibody binding to alpha-thalassaemic IRBCs and could be involved in the mechanism of malaria protection.
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PMID:The membrane characteristics of Plasmodium falciparum-infected and -uninfected heterozygous alpha(0)thalassaemic erythrocytes. 1213 62


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