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

Lipid transport in arthropods is achieved by highly specialized lipoproteins, which resemble those described in vertebrate blood. Here, we describe purification and characterization of the lipid-apolipoprotein complex, lipophorin (Lp), in the malaria vector mosquito Anopheles gambiae. We also describe the Lp-mediated lipid transfer to developing eggs and the distribution of the imported lipid in developing embryos. The density of the Lp complex was 1.135 g/ml with an apparent molecular weight of 630 kDa. It is composed of two major polypeptides, apoLp I (260 kDa) and apoLp II (74 kDa) and composed of 50% protein, 48% lipid and 2% carbohydrate (w/w). Hydrocarbon, cholesterol, phosphatidyl choline, phosphatidyl ethanolamine, cholesteryl ester and diacylglyceride were the major Lp-associated lipids. Using fluorescently tagged lipids, we observed patterns that suggest that in live developing oocytes, the Lp was taken up by a receptor-mediated endocytic process. Such process was blocked at low temperature and in the presence of excess unlabeled Lp, but not by bovine serum albumin. Imported Lp was segregated in the spherical yolk bodies (mean size 1.8 microm) and distributed evenly in the cortex of the oocyte. In embryonic larvae, before hatching, a portion of the fatty acid in vesicles was found evenly distributed along the body, whereas portion of phospholipids was accumulated in the intestine.
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PMID:Anopheles gambiae lipophorin: characterization and role in lipid transport to developing oocyte. 1665 Nov 84

After infection of a red blood cell (RBC), the malaria parasite, Plasmodium falciparum, increases the permeability of the host's plasma membrane by inducing new permeability pathways (NPPs). Single-channel patch-clamp experiments have shown the presence in infected RBCs of novel anion-selective channel types with low open-state probabilities at positive membrane potentials. These channels have been postulated to form the NPPs. Here, we have used a range of transport techniques to study whether electroneutral solutes use these channels or altered/separate pathways. Transport of the electroneutral solute sorbitol via the NPPs was found to increase by a small but significant amount after gross membrane depolarization. This is inconsistent with transport via a channel with a reduced open-state probability at positive membrane potentials. As has been demonstrated previously for parasite-induced anion currents, sorbitol transport in infected RBCs was found to be sensitive to the presence of bovine serum albumin (BSA). However, it remains to be shown whether the effect is due to serum/BSA altering a single channel type or activating a new pathway. In addition, the study highlights problems that can occur when using different transport techniques to study the NPPs.
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PMID:Solute transport via the new permeability pathways in Plasmodium falciparum-infected human red blood cells is not consistent with a simple single-channel model. 1684 Jul 35

Sulfosuccinimidyl-6-(biotinamido) hexanoate and derivatives thereof covalently bind to the epsilon-amino group of lysine residues. Our observation that access of the biotin derivative to specific lysine residues depends on conformational properties of the entire polypeptide chain prompted us to investigate whether differential biotinylation patterns of a protein can be used as indicators for conformational changes. Bovine serum albumin is a soluble protein with characteristic unfolding kinetics upon exposure to high temperature. First, we show that biotinylation patterns of proteins are highly reproducible. Second, we demonstrate by mass spectrometry and tandem mass spectrometry that unfolding of the protein correlates with the accessibility of the biotin derivative to specific lysine residues. We have applied this experimental strategy to the analysis of a cell-surface protein, viz. the human band 3 anion exchanger of erythrocytes infected with the malaria parasite Plasmodium falciparum. We found that Lys(826) in a highly flexible loop can be biotinylated in non-infected (but not infected) erythrocytes, confirming earlier observations (Winograd, E., and Sherman, I. W. (2004) Mol. Biochem. Parasitol. 138, 83-87) based on epitope-specific monoclonal antibodies suggesting that this region undergoes a conformational change upon infection.
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PMID:Use of biotin derivatives to probe conformational changes in proteins. 1754 62

In vitro cultivation of Plasmodium falciparum has been extremely useful in understanding the biology of the human malaria parasite as well as research on the discovery of new antimalarial drugs and vaccines. A chemically defined serum-free medium supplemented with lipid-rich bovine serum albumin (AlbuMAX I) offers the following advantages over human serum-supplemented media for the in vitro culture of P. falciparum: 1) improved growth profile, with more than a 2-fold higher yield of the parasites at any stage of the growth cycle; 2) suitability for in vitro antimalarial screening, as the parasites grown in AlbuMAX and human serum-supplemented media show similar sensitivity to standard and novel antimalarials as well as natural product extracts in the in vitro drug susceptibility assays; and 3) DNA microarray analysis comparing the global gene expression profile of sorbitol-synchronized P. falciparum trophozoites grown in the 2 different media, indicating minimal differences.
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PMID:Growth, drug susceptibility, and gene expression profiling of Plasmodium falciparum cultured in medium supplemented with human serum or lipid-rich bovine serum albumin [corrected]. 1808 74

In acute uncomplicated falciparum malaria, there is a continuum from mild to severe malaria. However, no mathematical system is available to predict uncomplicated falciparum malaria patients turning to severe malaria. This study aimed to devise a simple and reliable model of Malaria Severity Prognostic Score (MSPS). The study was performed in adult patients with acute uncomplicated falciparum malaria admitted to the Bangkok Hospital for Tropical Diseases between 2000 and 2005. Total 38 initial clinical parameters were identified to predict the usual recovery or deterioration to severe malaria. The stepwise multiple discriminant analysis was performed to get a linear discriminant equation. The results showed that 4.3% of study patients turned to severe malaria. The MSPS = 4.38 (schizontemia) + 1.62 (gametocytemia) + 1.17 (dehydration) + 0.14 (overweight by body mass index; BMI) + 0.05 (initial pulse rate) + 0.04 (duration of fever before admission) - 0.50 (past history of malaria in last 1 year) - 0.48 (initial serum albumin) - 5.66. Based on the validation study in other malaria patients, the sensitivity and specificity were 88.8% and 88.4%, respectively. We conclude that the MSPS is a simple screening tool for predicting uncomplicated falciparum malaria patients turning to severe malaria. However, the MSPS may need revalidation in different geographical areas before utilized at specific places.
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PMID:Predictive score of uncomplicated falciparum malaria patients turning to severe malaria. 1816 9

In the Kivu region located in east of the Democratic Republic of the Congo, malnutrition and malaria is a major cause of morbidity and mortality. The relationship between malaria and malnutrition is unclear and has never been studied in the Kivu region. This report presents an analysis of data from 5695 children aged 0 to 5 years, admitted to the paediatric ward of Lwiro hospital between November 1992 and February 2004. The weight/age (W/A) index and weight/height (W/H) index expressed with standard deviation in relation to the reference median were calculated (Z score). The association between protein-energetic malnutrition and malaria infection and nutritional indicators was measured based on prevalence ratios determined by univariate analysis and adjusted Odds Ratio (OR) derived using a multivariate model. The prevalence of malaria at the time of admission was 35.8 % (n=5695). The W/A and W/H indexes and serum albumin level were correlated with malaria-related morbidity. Logistic regression showed that high malaria OR was associated with both anthropometric nutritional indicators [WHZ > -2: OR (CI 95 %) 1.7 (1.4-2.2)] [WAZ > -2: OR (CI 95 %) 1.3 (1.1-1.6)] and biological nutritional indicators [serum albumin > or = 23 g/L: OR (CI 95 %) 1.6 (1.2-2.1)]. Our findings indicate that malnourished children at admission have a lower risk of malaria infection.
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PMID:[Protein-energy malnutrition and malaria-related morbidity in children under 59 months in the Kivu region of the Democratic Republic of the Congo]. 1847 73

The intraerythrocytic malaria parasite, Plasmodium falciparum maintains an intracellular pH (pH(i)) of around 7.3. If subjected to an experimentally imposed acidification the parasite extrudes H(+), thereby undergoing a pH(i) recovery. In a recent study, Bennett et al. [Bennett TN, Patel J, Ferdig MT, Roepe PD. P. falciparum Na(+)/H(+) exchanger activity and quinine resistance. Mol Biochem Parasitol 2007;153:48-58] used the H(+) ionophore nigericin, in conjunction with an acidic medium, to acidify the parasite cytosol, and then used bovine serum albumin (BSA) to scavenge the nigericin from the parasite membrane. The ensuing Na(+)-dependent pH(i) recovery, seen following an increase in the extracellular pH, was attributed to a plasma membrane Na(+)/H(+) exchanger. This is at odds with previous reports that the primary H(+) extrusion mechanism in the parasite is a plasma membrane V-type H(+)-ATPase. Here we present evidence that the Na(+)-dependent efflux of H(+) from parasites acidified using nigericin/BSA is attributable to Na(+)/H(+) exchange via residual nigericin remaining in the parasite plasma membrane, rather than to endogenous transporter activity.
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PMID:Acid extrusion from the intraerythrocytic malaria parasite is not via a Na(+)/H(+) exchanger. 1942 65

Infection of human erythrocytes with the malaria parasite Plasmodium falciparum induces activation of organic osmolyte and anion channels in the host cell membrane. These channels supply the intraerythrocytic parasite with nutrients, dispose of metabolic waste products, adjust the host electrolyte concentrations to the parasite's needs, and lower the colloid osmotic pressure, thus preventing premature hemolysis of the osmotically challenged host cell. Four different types of anion channels (CFTR, ClC-2 or PSAC, an 18pS inward rectifier, and an 80pS outward rectifier) have been identified in human erythrocytes. Here, we show that the 80pS channels underlie a serum albumin-dependent anion current. Both, the parasite in vitro development and the organic osmolyte permeability of the parasitized erythrocyte, reportedly depend on serum albumin, highlighting the pivotal functional significance of the 80pS channel for the intraerythrocytic parasite development.
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PMID:Organic osmolyte channels in malaria-infected erythrocytes. 1880 54

Viral hepatitis is common in Nigeria and may present with jaundice in pregnancy. The objective of this study was to determine the contribution of viral hepatitis among other aetiological factors, to the development of jaundice during pregnancy. Data on viral hepatitis among gravidae with jaundice in pregnancy over a 10-year period from 1st January 1992 through 31st December 2001 were retrieved and analyzed. Fifty-two cases of jaundice in pregnancy were seen among 16,566 pregnancies registered in the hospital over the 10-year period. Of the 52 cases of jaundice in pregnancy, only 48 case records were retrievable, on which this analysis is based. Viral hepatitis (VH) occurred in 1 in 591.6 pregnancies and was diagnosed in 28 (58.3%) cases of jaundice in pregnancy. Other causes of jaundice were malaria 8 (16.7%), sickle-cell anaemia in pregnancy 6 (12.5%) and sepsis 2 (4.2%). Of the 28 patients with viral hepatitis, 8 (28.5%) were positive for HBsAg. The liver function tests (LFTs) were done in 26 of the 28 patients and it showed hyperbilirubinaemia in 24, 11 had serum albumin >3.5 g/dl. All had spontaneous vaginal delivery with no maternal death. Complications associated with viral hepatitis were, anaemia 14 (50%), intrauterine growth retardation (14.3%), intrauterine foetal death 2 (7.1%), congestive cardiac failure 1 (3.57%) early neonatal death 1 (3.57%) and 2 (7.1%) cases of systemic hypertension. Viral hepatitis contributes significantly to jaundice in pregnancy and there is associated fetal and maternal morbidity.
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PMID:Viral hepatitis in the aetiogenesis of jaundice in pregnancy at the University College Hospital, Ibadan. 1920 72

Albumin has been used for volume resuscitation and supplementation in critically ill patients for over 50 years. While regarded as a "gold standard" colloid solution, albumin is associated with substantial cost, and questions have been raised about its safety and efficacy. A large-scale randomised controlled trial (the Saline vs. Albumin Fluid Evaluation [SAFE] study) demonstrated that albumin and saline were clinically equivalent treatments for intravascular volume resuscitation in a heterogenous population of critically ill patients. However, in patients with traumatic brain injury, albumin was associated with a significantly higher mortality and cannot be recommended for acute resuscitation of such patients. A potential beneficial role of albumin in patients with severe sepsis, particularly malaria, requires further study. Extrapolation of the results of the SAFE study to other, synthetic, colloid solutions requires caution, and a randomised controlled trial comparing albumin, starch and crystalloids in patients with severe sepsis is warranted. The safety of synthetic colloids in patients with traumatic brain injury should not be assumed. Although hypoalbuminaemia is associated with increased mortality, use of albumin for volume resuscitation of critically ill patients with a serum albumin concentration < or =25 g/L is not associated with reductions in mortality, duration of ICU stay or mechanical ventilation, or in use of renal replacement therapy. Similarly, there is no substantive evidence to justify the use of hyperoncotic albumin solutions for resuscitation or supplementation in critically ill patients. Albumin is a safe and effective resuscitation solution in critically ill patients without traumatic brain injury. However, the acquisition costs of albumin and synthetic colloids are more than those of crystalloids, and, as yet, colloids have not been proven to confer substantive benefits over crystalloids such as saline.
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PMID:Albumin is a blood product too - is it safe for all patients? 1928 47


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