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Holmberg V Schuster F Dietz E Sagarriga Visconti JC Anemana SD Bienzle U Mockenhaupt FP 《Microbes and infection / Institut Pasteur》2008,10(4):342-348
Mannose-binding lectin (MBL) is a serum protein which initiates innate immune responses to microbial pathogens by binding to non-self surface oligosaccharides. MBL deficiency is the most common congenital immunodeficiency of human and has been shown to predispose to infections, particularly in children and immune compromised. In a matched case-control study among 870 Ghanaian children, we examined the influence of six polymorphisms of the MBL2 gene on Plasmodium falciparum infection and severe malaria. A missense mutation resulting in low MBL activity (MBL2*C) was found in 35% of healthy controls, but in 42% of asymptomatically infected children (P=0.01), and in 46% of patients with severe malaria (P=0.007). Heterozygosity for MBL2*C was associated with increased odds of infection (odds ratio (OR), 1.6; 95% confidence interval (CI), 1.1-2.1), severe malaria (OR, 1.7; 95% CI, 1.2-2.4), and of severe anemia in particular (OR, 2.3; 95% CI, 1.4-3.8). The population attributable fraction of severe malaria cases attributable to MBL2*C heterozygosity was 17%. Our results suggest that the MBL pathway of the complement system is a critical determinant of both, susceptibility to P. falciparum infection and manifestation of severe malaria, particularly in young children in whom specific immune responses are weak or absent. 相似文献
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S. N. Muchohi B. R. Ogutu C. R. J. C. Newton G. O. Kokwaro 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2001,761(2)
A sensitive, selective and reproducible reversed-phase HPLC method with ultraviolet detection was developed for the quantification of diazepam in small plasma samples from children with severe malaria. The method involves plasma deproteinization with acetonitrile, followed by liquid–liquid extraction with ethyl acetate–n-hexane. Diazepam was eluted at ambient temperatures from a reversed-phase C18 column with an acidic (pH 3.5) aqueous mobile phase (10 mM KH2PO4–acetonitrile, 69:31, v/v). Calibration curves in spiked plasma were linear from 10 to 200 ng (r2≥0.99). The limit of detection was 5.0 ng/ml, and relative recoveries at 25 and 180 ng were >87%. Intra- and inter-assay relative standard deviations were <15%. There was no interference from drugs commonly administered to children with severe malaria (phenobarbitone, phenytoin, chloroquine, quinine, sulfadoxine, pyrimethamine, halofantrine, cycloguanil, chlorcycloguanil, acetaminophen and salicylate). This method has been used for monitoring plasma diazepam concentrations in children with seizures associated with severe malaria. 相似文献
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Intracranial volume and intracranial pressure have been measured in 66 children with craniosynostosis, 48 boys and 18 girls. The premature fusion of skull sutures is assumed to restrict skull growth and predispose to elevated intracranial pressure. Thirteen children (20 percent) had raised intracranial pressure and demonstrated a significant restriction of skull growth. In this series, volume measurement alone, however, did not serve as a reliable predictor that the intracranial pressure was raised. 相似文献
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Adjei George O Oduro-Boatey Collins Rodrigues Onike P Hoegberg Lotte C Alifrangis Michael Kurtzhals Jorgen A Goka Bamenla Q 《Malaria journal》2012,11(1):1-7
Background
In order to prepare the field site for future interventions, the prevalence of asymptomatic Plasmodium falciparum infection was evaluated in a cohort of children living in Brazzaville. Plasmodium falciparum merozoite surface protein 2 gene (msp2) was used to characterize the genetic diversity and the multiplicity of infection. The prevalence of mutant P. falciparum chloroquine resistance transporter (pfcrt) allele in isolates was also determined.Methods
Between April and June 2010, 313 children below 10 years of age enrolled in the cohort for malaria surveillance were screened for P. falciparum infection using microscopy and polymerase chain reaction (PCR). The children were selected on the basis of being asymptomatic. Plasmodium falciparum msp2 gene was genotyped by allele-specific nested PCR and the pfcrt K76T mutation was detected using nested PCR followed by restriction endonuclease digestion.Results
The prevalence of asymptomatic P. falciparum infections was 8.6% and 16% by microscopy and by PCR respectively. Allele typing of the msp2 gene detected 55% and 45% of 3D7 and FC27 allelic families respectively. The overall multiplicity of infections (MOI) was 1.3. A positive correlation between parasite density and multiplicity of infection was found. The prevalence of the mutant pfcrt allele (T76) in the isolates was 92%.Conclusion
This is the first molecular characterization of P. falciparum field isolates in Congolese children, four years after changing the malaria treatment policy from chloroquine (CQ) to artemisinin-based combination therapy (ACT). The low prevalence of asymptomatic infections and MOI is discussed in the light of similar studies conducted in Central Africa. 相似文献8.
Restricted postexercise pulmonary diffusion capacity and central blood volume depletion 总被引:3,自引:0,他引:3
Hanel Birgitte; Teunissen Inge; Rabol Alan; Warberg Jorgen; Secher Niels H. 《Journal of applied physiology》1997,83(1):11-17
Hanel, Birgitte, Inge Teunissen, Alan Rabøl,Jørgen Warberg, and Niels H. Secher. Restricted postexercisepulmonary diffusion capacity and central blood volume depletion.J. Appl. Physiol. 83(1): 11-17, 1997.Pulmonary diffusion capacity for carbon monoxide(DLCO),regional electrical impedance(Z0), and the distribution oftechnetium-99m-labeled erythrocytes together with concentration ofplasma atrial natriuretic peptide (ANP) were determined before andafter a 6-min "all-out" row in nine oarsmen and in six controlsubjects. Two and one-half hours after exercise in the upright seatedposition,DLCO wasreduced by 6 (2 to 21; median and range) %, thethoracic-to-thigh electrical impedance ratio(Z0 thorax/Z0 thigh)rose by 14 (1 to 29) %, paralleled by a 7 (3 to 11) % decrease and a 3 (5 to 12) % increase in the thoracic and thighblood volume, respectively. These responses were associated with adecrease in the plasma ANP concentration from 15 (13-31) to 12 (9-27) pmol/l (P < 0.05).Similarly, in the supine position,Z0 thorax/Z0 thighincreased by 10 (5 to 28) % whenDLCO wasreduced 12 (6-26) % (P < 0.05), whereasDLCO remained stable in the control group. The increase inZ0 thorax/Z0 thigh and the corresponding redistribution of the blood volume in both bodypositions show that approximately one-half of the postexercise reduction ofDLCO isexplained by a decrease in the pulmonary blood volume. The role of areduced postexercise central blood volume is underscored by the lowerplasma ANP, which aids in upregulating the blood volume after exercisein athletes. 相似文献
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Phiri HT Bridges DJ Glover SJ van Mourik JA de Laat B M'baya B Taylor TE Seydel KB Molyneux ME Faragher EB Craig AG Bunn JE 《PloS one》2011,6(11):e25626
Background
In spite of the significant mortality associated with Plasmodium falciparum infection, the mechanisms underlying severe disease remain poorly understood. We have previously shown evidence of endothelial activation in Ghanaian children with malaria, indicated by elevated plasma levels of both von Willebrand factor (VWF) and its propeptide. In the current prospective study of children in Malawi with retinopathy confirmed cerebral malaria, we compared these markers with uncomplicated malaria, non malarial febrile illness and controls.Methods and Findings
Children with cerebral malaria, mild malaria and controls without malaria were recruited into the study. All comatose patients were examined by direct and indirect ophthalmoscopy. Plasma VWF and propeptide levels were measured by ELISA. Median VWF and propeptide levels were significantly higher in patients with uncomplicated malaria than in children with non-malarial febrile illness of comparable severity, in whom levels were higher than in non-febrile controls. Median concentrations of both markers were higher in cerebral malaria than in uncomplicated malaria, and were similar in patients with and without retinopathy. Levels of both VWF and propeptide fell significantly 48 hours after commencing therapy and were normal one month later.Conclusions
In children with malaria plasma VWF and propeptide levels are markedly elevated in both cerebral and mild paediatric malaria, with levels matching disease severity, and these normalize upon recovery. High levels of both markers also occur in retinopathy-negative ‘cerebral malaria’ cases, many of whom are thought to be suffering from diseases other than malaria, indicating that further studies of these markers will be required to determine their sensitivity and specificity. 相似文献11.
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S Carrière J Cardinal C LeGrimellec 《Canadian journal of physiology and pharmacology》1979,57(7):681-687
Norepinephrine (NE) release and pressor response to sympathetic stimulation were studied in dogs under furosemide-induced acute volume depletion. The rise in blood pressure observed following carotid clamping proved similar before and after acute salt and water depletion in the first group of animals and NE rose comparably in these two conditions. Similar results were obtained in a second group of dogs that received an angiotensin II converting enzyme inhibitor (CEI). This study shows that contrary to isotonic saline loading, acute salt and water depletion cause a progressive increase in NE plasma levels. Moreover, these results clearly demonstrate that the decrease in sympatho--adrenergic response and the predominant role played by the renin--aniotensin system during chronic salt depletion are not observed in acute conditions. 相似文献
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White Nicholas J Ashley Elizabeth A Recht Judith Delves Michael J Ruecker Andrea Smithuis Frank M Eziefula Alice C Bousema Teun Drakeley Chris Chotivanich Kesinee Imwong Mallika Pukrittayakamee Sasithon Prachumsri Jetsumon Chu Cindy Andolina Chiara Bancone Germana Hien Tran T Mayxay Mayfong Taylor Walter RJ von Seidlein Lorenz Price Ric N Barnes Karen I Djimdé Abdoulaye ter Kuile Feiko Gosling Roly Chen Ingrid Dhorda Mehul J Stepniewska Kasia Guérin Philippe Woodrow Charles J Dondorp Arjen M Day Nicholas PJ Nosten Francois H 《Malaria journal》2014,13(1):1-14
Background
Effective mating between laboratory-reared males and wild females is paramount to the success of vector control strategies aiming to decrease disease transmission via the release of sterile or genetically modified male mosquitoes. However mosquito colonization and laboratory maintenance have the potential to negatively affect male genotypic and phenotypic quality through inbreeding and selection, which in turn can decrease male mating competitiveness in the field. To date, very little is known about the impact of those evolutionary forces on the reproductive biology of mosquito colonies and how they ultimately affect male reproductive fitness.Methods
Here several male reproductive physiological traits likely to be affected by inbreeding and selection following colonization and laboratory rearing were examined. Sperm length, and accessory gland and testes size were compared in male progeny from field-collected females and laboratory strains of Anopheles gambiae sensu stricto colonized from one to over 25 years ago. These traits were also compared in the parental and sequentially derived, genetically modified strains produced using a two-phase genetic transformation system. Finally, genetic crosses were performed between strains in order to distinguish the effects of inbreeding and selection on reproductive traits.Results
Sperm length was found to steadily decrease with the age of mosquito colonies but was recovered in refreshed strains and crosses between inbred strains therefore incriminating inbreeding costs. In contrast, testes size progressively increased with colony age, whilst accessory gland size quickly decreased in males from colonies of all ages. The lack of heterosis in response to crossing and strain refreshing in the latter two reproductive traits suggests selection for insectary conditions.Conclusions
These results show that inbreeding and selection differentially affect reproductive traits in laboratory strains overtime and that heterotic ‘supermales’ could be used to rescue some male reproductive characteristics. Further experiments are needed to establish the exact relationship between sperm length, accessory gland and testes size, and male reproductive success in the laboratory and field settings. 相似文献14.
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FA Jonker JC Calis MB van Hensbroek K Phiri RB Geskus BJ Brabin T Leenstra 《PloS one》2012,7(8):e42670
Introduction
Iron deficiency is highly prevalent in pre-school children in developing countries and an important health problem in sub-Saharan Africa. A debate exists on the possible protective effect of iron deficiency against malaria and other infections; yet consensus is lacking due to limited data. Recent studies have focused on the risks of iron supplementation but the effect of an individual''s iron status on malaria risk remains unclear. Studies of iron status in areas with a high burden of infections often are exposed to bias. The aim of this study was to assess the predictive value of baseline iron status for malaria risk explicitly taking potential biases into account.Methods and materials
We prospectively assessed the relationship between baseline iron deficiency (serum ferritin <30 µg/L) and malaria risk in a cohort of 727 Malawian preschool children during a year of follow-up. Data were analyzed using marginal structural Cox regression models and confounders were selected using causal graph theory. Sensitivity of results to bias resulting from misclassification of iron status by concurrent inflammation and to bias from unmeasured confounding were assessed using modern causal inference methods.Results and Conclusions
The overall incidence of malaria parasitemia and clinical malaria was 1.9 (95% CI 1.8–2.0) and 0.7 (95% CI 0.6–0.8) events per person-year, respectively. Children with iron deficiency at baseline had a lower incidence of malaria parasitemia and clinical malaria during a year of follow-up; adjusted hazard ratio''s 0.55 (95%-CI:0.41–0.74) and 0.49 (95%-CI:0.33–0.73), respectively. Our results suggest that iron deficiency protects against malaria parasitemia and clinical malaria in young children. Therefore the clinical importance of treating iron deficiency in a pre-school child should be weighed carefully against potential harms. In malaria endemic areas treatment of iron deficiency in children requires sustained prevention of malaria. 相似文献16.
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. 相似文献
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Jonas Spaak Stéphanie Montmerle Patrik Sundblad Dag Linnarsson 《Journal of applied physiology》2005,98(2):648-654
Long-term head-down-tilt bed rest (HDT) causes cardiovascular deconditioning, attributed to reflex dysfunctions, plasma volume reduction, or cardiac impairments. Our objective with the present study was to evaluate the functional importance and relative contribution of these during rest and exercise in supine and upright postures. We studied six subjects before (baseline), during [days 60 (D60) and 113 (D113)], and after [recovery days 0 (R0), 3 (R3), and 15 (R15)] 120 days of -6 degrees HDT. We determined cardiac output, stroke volume (SV), mean arterial pressure, and heart rate during rest and exercise in supine and upright postures. Cardiac output and SV decreased significantly in all four conditions, but the time courses differed for rest and exercise. Upright resting SV was decreased by 24 +/- 9% at D60 compared with baseline but had recovered already at R3. Supine exercise SV decreased more slowly (by 5 +/- 8% at D60 and by 18 +/- 4% at D113) and recovered more slowly after HDT termination. Steady-state mean arterial pressure showed no changes. Heart rate had increased by 18 +/- 4% at D60 and had recovered partially at R3. Our data indicate that long-term HDT causes both a rapid, preload-dependent reduction in SV, most evident during rest in the upright position, and a more slowly developing cardiac dysfunction, most evident during supine exercise. However, the ability to maintain blood pressure and to perform sustained low levels of dynamic exercise is not influenced by HDT. 相似文献
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Richard Idro Godfrey Otieno Steven White Anderson Kahindi Greg Fegan Bernhards Ogutu Sadik Mithwani Kathryn Maitland Brian GR Neville Charles RJC Newton 《Malaria journal》2005,4(1):1-10