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

The unresolved and complex relationship between nitric oxide and falciparum malaria is reflected in recent genetic and immunohistochemical studies in African children. Different genetic associations, perhaps geographically distinctive, are seen between genetic variants of the inducible nitric oxide gene and various disease manifestations in African populations. The picture might not be complete without considering the emerging roles of carbon monoxide, another endogenous gaseous mediator with similar effects to those of nitric oxide. Only when genetic comparisons from across tropical Africa are examined, in conjunction with the newly recognized complexities in the events of systemic inflammation, will this relationship be understood.
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PMID:Genes, nitric oxide and malaria in African children. 1290 31

BACKGROUND: As well as being inducible by haem, haemoxygenase -1 (HO-1) is also induced by interleukin-10 and an anti-inflammatory prostaglandin, 15d PGJ2, the carbon monoxide thus produced mediating the anti-inflammatory effects of these molecules. The cellular distribution of HO-1, by immunohistochemistry, in brain, lung and liver in fatal falciparum malaria, and in sepsis, is reported. METHODS: Wax sections were stained, at a 1:1000 dilution of primary antibody, for HO-1 in tissues collected during paediatric autopsies in Blantyre, Malawi. These comprised 37 acutely ill comatose patients, 32 of whom were diagnosed clinically as cerebral malaria and the other 5 as bacterial diseases with coma. Another 3 died unexpectedly from an alert state. Other control tissues were from Australian adults. RESULTS: Apart from its presence in splenic red pulp macrophages and microhaemorrhages, staining for HO-1 was confined to intravascular monocytes and certain tissue macrophages. Of the 32 clinically diagnosed cerebral malaria cases, 11 (category A) cases had negligible histological change in the brain and absence of or scanty intravascular sequestration of parasitized erythrocytes. Of these 11 cases, eight proved at autopsy to have other pathological changes as well, and none of these eight showed HO-1 staining within the brain apart from isolated moderate staining in one case. Two of the three without another pathological diagnosis showed moderate staining of scattered monocytes in brain vessels. Six of these 11 (category A) cases exhibited strong lung staining, and the Kupffer cells of nine of them were intensely stained. Of the seven (category B) cases with no histological changes in the brain, but appreciable sequestered parasitised erythrocytes present, one was without staining, and the other six showed strongly staining, rare or scattered monocytes in cerebral vessels. All six lung sections not obscured by neutrophils showed strong staining of monocytes and alveolar macrophages, and all six available liver sections showed moderate or strong staining of Kupffer cells. Of the 14 (category C) cases, in which brains showed micro-haemorrhages and intravascular mononuclear cell accumulations, plus sequestered parasitised erythrocytes, all exhibited strong monocyte HO-1 staining in cells forming accumulations and scattered singly within cerebral blood vessels. Eleven of the available and readable 13 lung sections showed strongly staining monocytes and alveolar macrophages, and one stained moderately. All of the 14 livers had strongly stained Kupffer cells. Of five cases of comatose culture-defined bacterial infection, three showed a scattering of stained monocytes in vessels within the brain parenchyma, three had stained cells in lung sections, and all five demonstrated moderately or strongly staining Kupffer cells. Brain sections from all three African controls, lung sections from two of them, and liver from one, showed no staining for HO-1, and other control lung and liver sections showed few, palely stained cells only. Australian-origin adult brains exhibited no staining, whether the patients had died from coronary artery disease or from non-infectious, non-cerebral conditions CONCLUSIONS: Clinically diagnosed 'cerebral malaria' in children includes some cases in whom malaria is not the only diagnosis with the hindsight afforded by autopsy. In these patients there is widespread systemic inflammation, judged by HO-1 induction, at the time of death, but minimal intracerebral inflammation. In other cases with no pathological diagnosis except malaria, there is evidence of widespread inflammatory responses both in the brain and in other major organs. The relative contributions of intracerebral and systemic host inflammatory responses in the pathogenesis of coma and death in malaria deserve further investigation.
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PMID:Induction of HO-1 in tissue macrophages and monocytes in fatal falciparum malaria and sepsis. 1462 2

BACKGROUND: Removal of exhaled air from total body emanations or artificially standardising carbon dioxide (CO2) outputs has previously been shown to eliminate differential attractiveness of humans to certain blackfly (Simuliidae) and mosquito (Culicidae) species. Whether or not breath contributes to between-person differences in relative attractiveness to the highly anthropophilic malaria vector Anopheles gambiae sensu stricto remains unknown and was the focus of the present study. METHODS: The contribution to and possible interaction of breath (BR) and body odours (BO) in the attraction of An. gambiae s.s. to humans was investigated by conducting dual choice tests using a recently developed olfactometer. Either one or two human subjects were used as bait. The single person experiments compared the attractiveness of a person's BR versus that person's BO or a control (empty tent with no odour). His BO and total emanations (TE = BR+BO) were also compared with a control. The two-person experiments compared the relative attractiveness of their TE, BO or BR, and the TE of each person against the BO of the other. RESULTS: Experiments with one human subject (P1) as bait found that his BO and TE collected more mosquitoes than the control (P = 0.005 and P < 0.001, respectively), as did his BO and the control versus his BR (P < 0.001 and P = 0.034, respectively). The TE of P1 attracted more mosquitoes than that of another person designated P8 (P < 0.021), whereas the BR of P8 attracted more mosquitoes than the BR of P1 (P = 0.001). The attractiveness of the BO of P1 versus the BO of P8 did not differ (P = 0.346). The BO from either individual was consistently more attractive than the TE from the other (P < 0.001). CONCLUSIONS: We demonstrated for the first time that human breath, although known to contain semiochemicals that elicit behavioural and/or electrophysiological responses (CO2, ammonia, fatty acids) in An. gambiae also contains one or more constituents with allomonal (~repellent) properties, which inhibit attraction and may serve as an important contributor to between-person differences in the relative attractiveness of humans to this important malaria vector.
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PMID:Allomonal effect of breath contributes to differential attractiveness of humans to the African malaria vector Anopheles gambiae. 1474 30

Disease vector female mosquitoes respond to physic-chemical signals to localize vertebrate hosts for blood meals. Zoophylic mosquitoes preferentially respond to CO2 and octenol released in the breath and bodily fluids, while anthropophylic mosquitoes respond to lactic acid and a variety of sweat compounds. These compounds are modified by saprophytic microorganisms in the skin sebaceous glands. Other factors present in human dwellings contribute to the integration of microsystems with characteristic odors that have different attraction for mosquitoes, explaining the focalization of malaria transmission in few households in endemic areas. The identification of the chemical attractants and their molecular receptors could be used to complement new methods to attract mosquitoes to traps during epidemiological surveys, to increase their contact with insecticides in control interventions, and for genetic manipulation to divert mosquito bites towards other animal populations. The English version of this paper is available at:http://www.insp.mx/salud/index.html.
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PMID:[Physico-chemical signals involved in host localization and in the induction of mosquito bites]. 1497 94

Heme oxygenase (HO) is thought to be induced in severe malaria, but the pathophysiologic consequences have not been examined. It is induced by hemolysis, oxidative stress, and inflammation. It degrades heme, producing carbon monoxide (CO), which causes elevated levels of carboxyhemoglobin (COHb). In a prospective study of 1,520 children admitted to a Kenyan district hospital, COHb levels were no higher in children with malaria than with other infections. The COHb levels in children with severe malarial anemia were higher than in other children with malaria, but significantly lower than in children with other causes of severe anemia such as sickle cell disease. Levels of COHb were not significantly higher in children with cerebral malaria or in those dying of malaria. These results do not support a systemic increase in HO activity in malaria compared with other infectious diseases, but the roles of HO and CO in malaria require further study.
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PMID:Carboxyhemoglobin levels in Kenyan children with Plasmodium falciparum malaria. 1523 87

There is now wide acceptance of the concept that the similarity between many acute infectious diseases, be they viral, bacterial, or parasitic in origin, is caused by the overproduction of inflammatory cytokines initiated when the organism interacts with the innate immune system. This is also true of certain noninfectious states, such as the tissue injury syndromes. This review discusses the historical origins of these ideas, which began with tumor necrosis factor (TNF) and spread from their origins in malaria research to other fields. As well the more established proinflammatory mediators, such as TNF, interleukin-1, and lymphotoxin, the roles of nitric oxide and carbon monoxide, which are chiefly inhibitory, are discussed. The established and potential roles of two more recently recognized contributors, overactivity of the enzyme poly(ADP-ribose) polymerase 1 (PARP-1) and the escape of high-mobility-group box 1 (HMGB1) protein from its normal location into the circulation, are also put in context. The pathogenesis of the disease caused by falciparum malaria is then considered in the light of what has been learned about the roles of these mediators in these other diseases, as well as in malaria itself.
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PMID:Pathogenesis of malaria and clinically similar conditions. 1525 91

The role of haem iron (II) and oxidative stress in the activation and antimalarial activity of artemisinin is unclear. Thus, we submitted malaria parasite to modified culture conditions: artemisinin activity increased by 20-30% under an oxygen-rich atmosphere (20% O2 instead of "standard" 1% O2), and by 40-50% in the presence of carboxy-haemoglobin, and 2% carbon monoxide, conditions which inhibit haem iron (II) reactivity. In all cases, parasite growth and chloroquine activity were unaffected. We conclude that in the malaria parasite artemisinin is not activated by haem iron and that free radicals are not needed for its toxicity.
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PMID:Evidence that haem iron in the malaria parasite is not needed for the antimalarial effects of artemisinin. 1538 39

Malaria was once endemic in the Osijek region of Croatia and although it has been eradicated, there are still several vector species of the Anopheles maculipennis complex in this area. During an eight-year investigation, using CDC traps with CO2 as an attractant, we collected a total of 3,508 mosquitoes. We determined the dynamics of members of this complex and found that they varied considerably with an average of two generations per season. Cross-correlations indicated that the Spearman's Index between the abundance rate and the water level was the highest 12 and 24 d before traps were set. This suggests that the long-term high water level created better conditions for continuous breeding of mosquitoes, which contributed to a significant increase in abundance rates of all species in the complex.
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PMID:Seasonal dynamics of the Anopheles maculipennis complex in Osijek, Croatia. 1570 85

The first successful in vitro cultivation of Plasmodium falciparum in sickle cells in a gas mixture containing 3% oxygen, 4% carbon dioxide and 93% nitrogen has been reported recently, contradicting earlier claims that the parasite does not multiply continuously in sickle cell trait (HbAS) and sickle cell anemia (HbSS) erythrocytes at low oxygen tension. The present study extends that report by growing three P. falciparum strains in erythrocytes from four different sickle cell trait and four sickle cell anemia donors. Because P. falciparum is known to grow normally in sickle cells when incubated in a candle-jar estimated to contain 15-18% oxygen, we have also compared the growth at 3% oxygen with that in a candle-jar. For convenience, we also refer to the 3% oxygen and the candle-jar as low and high oxygen environment, respectively. The three P. falciparum strains were first grown continuously in low oxygen environment for at least 1 month in erythrocytes from one HbAS carrier. These stock cultures were then used to infect erythrocytes from additional three HbAS carriers and four HbSS patients. Results of the experiments showed that parasite growth and hemozoin production in HbAS erythrocytes in low oxygen environment were comparable to those obtained in the candle-jar. There was growth retardation in HbSS erythrocytes in low oxygen environment, but some of the parasites survived and eventually produced high parasitemia levels. Continuous cultivation of different P. falciparum strains in HbAS erythrocytes is necessary for investigation of possible molecular differences between malaria parasites in sickle cells and those in HbAA erythrocytes.
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PMID:Comparison of Plasmodium falciparum growth in sickle cells in low oxygen environment and candle-jar. 1577 3

Malaria transmission is dependent upon many hydrology-driven ecological factors that directly affect the vectorial competence, including the presence of suitable habitats for the development of anopheline larvae. Larval habitats were identified and characterized at three malaria endemic villages (Ban Khun Huay, Ban Pa Dae, and Ban Tham Seau) in Mae Sot district, Tak Province, in northwestern Thailand between July 2002 and June 2003. The Global Positioning System (GPS) was used to provide precise locational data for the spatial distribution of anopheline mosquito larvae and their habitats. Ten habitat categories were identified. Eighteen adult Anopheles species were identified from larvae in all the surveyed habitats. An. minimus was the most common species throughout the year. The relationship between eight abiotic variables (temperature, hardness, carbon dioxide, dissolved oxygen, nitrate, phosphate, silica and pH) and the abundance of four major species of malaria vectors (An. (Cel.) dirus, An. (Cel.) minimus, An. (Cel.) maculatus, and An. (Cel.) sawadwongporni), and six species of non-vectors (An. (Cel.) kochi, An. (Cel.) jamesii, An. (Ano.) peditaeniatus, An. (Ano.) barbirostris, An. (Ano.) campestris, and An (Cel.) vagus) larvae was investigated. The results from the multiple regression models suggest that hardness, water temperature and carbon dioxide are the best predictor variables associated with the abundance of An. minimus larvae (p < 0.001); water pH for An. dirus larvae (p < 0.001); temperature and pH for An. kochi larvae (p < 0.01); temperature and silica concentration for An. jamesii larvae (p < 0.001); dissolved oxygen and silica concentration for An. campestris larvae (p < 0.001); and pH and silica concentration for An. vagus larvae (p < 0.001). We could not identify key environmental variables for An. maculatus, An. sawadwongporni, An. peditaeniatus, and An. barbirostris.
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PMID:Water quality and breeding habitats of anopheline mosquito in northwestern Thailand. 1590 41


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