Natural killer cell IFN-gamma-activity is associated with Plasmodium falciparum infection during pregnancy.

The ability of natural killer (NK) cells to produce gamma interferon (IFN-gamma) after ex vivo stimulation with crude schizont lysate of Plasmodium falciparum was studied in uninfected and P. falciparum-infected pregnant Gabonese women segregated according to the gravidity at the time of delivery. This activity was measured in purified NK cells as well as in whole blood from the periphery and cord.

Markers of vascular endothelial cell damage and P. falciparum malaria: association between levels of both sE-selectin and thrombomodulin, and cytokines, hemoglobin and clinical presentation.

We investigated associations between markers of damage of vascular endothelial cells (MDVECs) and plasma cytokine levels, hemoglobin level and temperature in individuals with acute uncomplicated malaria, as well as healthy controls, using enzyme linked immunosorbent assay (ELISA) for the presence of soluble endothelial cell adhesion molecule-1 (sE-selectin), circulating granule membrane protein-140 (sP-selectin), circulating thrombomodulin (TM), circulating von Willebrand factor (VWf), interferon gamma (IFN-gamma) and tumor necrosis factor alpha (TNF-alpha). Significant differences were observed between falciparum malaria patients and the healthy people in term of levels of both sE-selectin and TM. The serum levels of sP-selectin and VWf were comparable between the two groups.

Cytokine profiles in peripheral, placental and cord blood in an area of unstable malaria transmission in eastern Sudan.

Background: Understanding the cytokine interactions that underlie both control and disease should be helpful when investigating the pathogenesis of malaria during pregnancy. Few data exists concerning pathogenesis of malaria during pregnancy in areas of unstable malaria transmission.

Objectives: The study was conducted in New Halfa hospital, eastern Sudan, which is characterized by unstable malaria transmission to investigate the cytokine profiles in peripheral, placental and cord blood in parturient women.

Antipyretic effect of ibuprofen in Gabonese children with uncomplicated falciparum malaria: a randomized, double-blind, placebo-controlled trial.

Background: Antipyretic drugs are widely used in children with fever, though there is a controversy about the benefit of reducing fever in children with malaria. In order to assess the effect of ibuprofen on fever compared to placebo in children with uncomplicated Plasmodium falciparum malaria in Gabon, a randomized double blind placebo controlled trial, was designed.

Methods: Fifty children between two and seven years of age with uncomplicated malaria were included in the study.

Interleukin-21 is associated with IgG1 and IgG3 antibodies to erythrocyte-binding antigen-175 peptide 4 of Plasmodium falciparum in Gabonese children with acute falciparum malaria.

Interleukin-21 (IL-21) is a newly described, typical, four-helix cytokine showing significant homology with IL-2, IL-4 and IL-15. It regulates IgG1 production and co-operates with IL-4 in the production of multiple antibody classes in vivo. IgG1 and IgG3 are critically involved in the development of clinical immunity to Plasmodium falciparum malaria.

Ibuprofen does not affect levels of tumor necrosis factor alpha and soluble tumor necrosis factor receptor types I and II in Gabonese children with uncomplicated Plasmodium falciparum malaria.

We assessed the ability of ibuprofen to modulate tumor necrosis factor alpha (TNF-alpha), soluble tumor necrosis factor receptor type I (sTNFR-I), and soluble tumor necrosis factor receptor type II (sTNFR-II) responses during the treatment of fever in uncomplicated Plasmodium falciparum malaria, in a placebo-controlled, randomized, double-blind study of 50 pediatric patients in Lambaréné, Gabon. Treatment of the malaria involved the patients receiving intravenous quinine (12 mg/kg of quinine dihydrochloride every 12 h for 72 h) followed by a single dose of oral sulfadoxine/pyrimethamine (25 mg and 1.25 mg/kg).

A Duffy binding-like domain is involved in the NKp30-mediated recognition of Plasmodium falciparum-parasitized erythrocytes by natural killer cells.

The recent demonstration that purified natural killer (NK) cells lyse Plasmodium falciparum-parasitized red blood cells (Pf-pRBCs) suggests that innate immunity is important in malaria. NK cell killing--presumably an early host response to infection--requires intimate contact between NK natural cytotoxicity receptors (NCRs) and ligands expressed on the surface of Pf-pRBCs. We investigated whether the Duffy binding-like (DBL)-1 alpha domain of P.

History and perspectives of medical research at the Albert Schweitzer Hospital in Lambaréné, Gabon.

In 1913 Albert Schweitzer founded one of the first modern hospitals in Africa dedicated to the health of the local population. The Albert Schweitzer Hospital is located in Lambaréné, a small town in Gabon. In 1981 a research department--the Medical Research Unit--was established with the aim to perform research in the field of infectious diseases ( www.

Interactions between natural killer cells, cortisol and prolactin in malaria during pregnancy.

Natural killer cells derived from pluripotent hematopoietic stem cells are important cells of the immune system that have two main functions: a cytolytic activity and a cytokine-producing capacity. These functions are tightly regulated by numerous activating and inhibitory receptors, including newly discovered receptors that selectively trigger the cytolytic activity in a major histocompatibility complex independent manner. Based on their defining function of spontaneous cytotoxicity without prior immunization, natural killer (NK) cells have been thought to play a critical role in immune surveillance and cancer therapy.

Imbalanced distribution of Plasmodium falciparum EBA-175 genotypes related to clinical status in children from Bakoumba, Gabon.

Objective: The erythrocyte binding antigen 175 kDa (EBA-175) of Plasmodium falciparum is one of the major ligands for red blood cell invasion by merozoites. EBA-175 is a dimorphic antigen but the role that dimorphism plays in host parasite interaction is not fully understood. In this study, we sought to determine the distribution of EBA-175 genotypes and its pathogenetic influence.

Distribution of IgG subclass antibodies specific for Plasmodium falciparum glutamate-rich-protein molecule in sickle cell trait children with asymptomatic infections.

Polymorphism in the beta-globin gene (hemoglobin S) has been associated with protection against severe forms of malaria. In a cross-sectional study, 180 young Gabonese children with and without sickle cell trait and harboring asymptomatic Plasmodium falciparum infections, were assessed for the responses to recombinant protein containing the conserved region of glutamate-rich protein (GLURP). We reported increased age-dependence of antibody prevalence and levels of total IgG (p<0.

Hypothalamic-pituitary gonadal axis and immune response imbalance during chronic filarial infections.

Bi-directional relationships operate between the hypothalamic-pituitary-gonadal axis and the immune system. Cytokines, peptide hormones and their shared receptors/ligands are used as a common biological language for communication within and between the immune and neuroendocrine systems. Such communication suggests an immunoregulatory role for the brain and a sensory function for the immune system.

Cortisol and susceptibility to malaria during pregnancy.

We measured cortisol and prolactin concentrations in the peripheral venous blood of 23 non-pregnant and 59 pregnant Gabonese women from the second trimester of pregnancy until delivery. Cortisol concentrations were significantly higher in primigravidae women than in multigravidae women between 20 and 25 weeks' gestational age (166 vs. 132 ng/ml, respectively), between 28 and 37 weeks (226 vs.

Inhibition of human immunodeficiency virus type-1 (HIV-1) glycoprotein-mediated cell-cell fusion by immunor (IM28).

Background: Immunor (IM28), an analog of dehydroepiandrosterone (DHEA), inhibits human immunodeficiency virus type-1 (HIV-1) by inhibiting reverse transcriptase. We assessed the ability of IM28 to inhibit the cell-cell fusion mediated by HIV envelope glycoprotein in an in vitro system. For this purpose, we co-cultured TF228.

Effects of prolactin and cortisol on natural killer (NK) cell surface expression and function of human natural cytotoxicity receptors (NKp46, NKp44 and NKp30).

The surface density of the triggering receptors (e.g. NKp46 and NKp30) responsible for natural killer (NK) cell-mediated cytotoxicity determines the ability of NK cells to kill susceptible target cells.

Cytokine profiles in peripheral, placental and cord blood in pregnant women from an area endemic for Plasmodium falciparum.

During gestation, inflammatory cytokines are sometimes more abundant than growth-promoting cytokines, and via direct or indirect effects, proinflammatory cytokines lead to intrauterine growth retardation. We used an enzyme-linked immunosorbent assay to measure the concentrations of three proinflammatory cytokines, tumor necrosis factor alpha (TNF-alpha), interleukin-12 (IL-12p40), as well as interleukin-15 (IL-15) and monocyte chemotactic protein-1 (MCP-1), in plasma from peripheral, placental and cord blood of thirty pregnant Gabonese women. All of these women lived in Libreville and Lambaréné, two malaria hyperendemic areas.

Variations in the serum concentrations of soluble Fas and soluble Fas ligand in Vietnamese patients infected with hepatitis B virus.

Earlier studies of both chronic hepatitis B and C virus (HBV and HCV) patients have shown a strong correlation between the soluble membrane Fas (sFas) and Fas protein expression on hepatocytes. The serum concentrations of sFas and soluble Fas ligand (sFasL) was examined in both healthy and HBV-infected Vietnamese patients to determine their relationship with the outcome of HBV infection. Patients with chronic rather than acute HBV had significantly higher amounts of sFas and sFasL, whilst the highest concentrations of both molecules were detected in those with malignant forms of HBV infection.

Depressed natural killer cell cytotoxicity against Plasmodium falciparum-infected erythrocytes during first pregnancies.

We measured natural killer (NK) cell cytotoxicity and cortisol and prolactin concentrations in peripheral venous blood samples obtained from pregnant Gabonese women at the time of delivery. The NK cell-mediated cytotoxicity against Plasmodium falciparum-infected erythrocytes in vitro was lower in samples obtained from primiparous women than in samples obtained from multiparous women; cortisol concentrations were significantly higher in primiparous women than in multiparous women, and prolactin concentrations were significantly lower. The highest cortisol concentrations were found in the plasma of P.

Severe malarial anemia associated with increased soluble Fas ligand (sFasL) concentrations in Gabonese children.

To investigate if severe malarial anemia is associated with specific cytokine overproduction, we evaluated serum levels of soluble Fas ligand (sFasL), tumor necrosis factor (TNF-alpha) and interleukin-10 (IL-10) from three groups of young children with Plasmodium falciparum infection (asymptomatic cases, uncomplicated malaria cases and severe malarial anemia cases), in a hyperendemic area of Gabon. In uncomplicated cases, only TNF levels were significantly (p < 0.001) increased in comparison to asymptomatic cases with P.

Natural killer (NK) cell-mediated cytolysis of Plasmodium falciparum-infected human red blood cells in vitro.

The ability of human NK cells to inhibit the growth in vitro of the asexual blood stages of Plasmodium falciparum was tested. Purified NK cells from donors with no prior exposure to malaria significantly inhibited parasite growth after 48 hours of co-culture in the presence of human immune serum. This inhibition was completely abrogated by pre-treatment of the NK cells with an anti-CD95 (anti-Fas) monoclonal antibody and human Fas-Fc soluble protein.

Prevalence of Plasmodium falciparum infection in pregnant women in Gabon.

Background: In areas where malaria is endemic, pregnancy is associated with increased susceptibility to malaria. It is generally agreed that this risk ends with delivery and decreases with the number of pregnancies. Our study aimed to demonstrate relationships between malarial parasitaemia and age, gravidity and anaemia in pregnant women in Libreville, the capital city of Gabon.

Inflammatory responses in Ebola virus-infected patients.

Ebola virus subtype Zaire (Ebo-Z) induces acute haemorrhagic fever and a 60-80% mortality rate in humans. Inflammatory responses were monitored in victims and survivors of Ebo-Z haemorrhagic fever during two recent outbreaks in Gabon. Survivors were characterized by a transient release in plasma of interleukin-1beta (IL-1beta), IL-6, tumour necrosis factor-alpha (TNFalpha), macrophage inflammatory protein-1alpha (MIP-1alpha) and MIP-1beta early in the disease, followed by circulation of IL-1 receptor antagonist (IL-1RA) and soluble receptors for TNFalpha (sTNF-R) and IL-6 (sIL-6R) towards the end of the symptomatic phase and after recovery.

Enhancement of natural killer cell activation and antibody-dependent cellular cytotoxicity by interferon-alpha and interleukin-12 in vaginal mucosae Sivmac251-infected Macaca fascicularis.

We studied the innate immune system of Cynomolgus monkeys (Macaca fascicularis) experimentally infected via the vaginal mucosae with a virulent simian immunodeficiency virus isolate SIVmac251. Animals were evaluated for their natural killer (NK) cell activity, and for their antibody-dependent cellular cytotoxicity. NK cells from SIVmac251-infected macaques show impaired NK cell activity compared to cells from uninfected animals.

Sequence analysis of the GP, NP, VP40 and VP24 genes of Ebola virus isolated from deceased, surviving and asymptomatically infected individuals during the 1996 outbreak in Gabon: comparative studies and phylogenetic characterization.

The aims of this study were to determine if the clinical outcome of Ebola virus (EBOV) infection is associated with virus genetic structure and to document the genetic changes in the Gabon strains of EBOV by sequencing the GP, NP, VP40 and VP24 genes from deceased and surviving symptomatic and asymptomatic individuals. GP and NP sequences were identical in the three groups of patients and only one silent substitution occurred in the VP40 and VP24 genes in asymptomatic individuals. A strain from an asymptomatic individual had a reverse substitution to the Gabon-94 sequence, indicating that minor virus variants may cocirculate during an outbreak.