A Toll-like receptor-1 variant and its characteristic cellular phenotype is associated with severe malaria in Papua New Guinean children.

Genetic factors are likely to contribute to low severe malaria case fatality rates in Melanesian populations, but association studies can be underpowered and may not provide plausible mechanistic explanations if significant associations are detected. In preparation for a genome-wide association study, 29 candidate single-nucleotide polymorphisms (SNPs) with minor allele frequencies >5% were examined in a case-control study of 504 Papua New Guinean children with severe malaria. In parallel, an immunological substudy was performed on convalescent peripheral blood mononuclear cells (PBMCs) from cases and controls. Following stimulation with a Toll-like receptor (TLR) 1/2 agonist, effector cytokines and chemokines were assayed. The only significant genetic association observed involved a nonsynonymous SNP (TLR1rs4833095) in the TLR1 gene. A recessive (TT) genotype was associated with reduced odds of severe malaria of 0.52 (95% confidence interval (0.29-0.90), P=0.006). Concentrations of pro-inflammatory cytokines interleukin-1ß and tumour necrosis factor α were significantly higher in severe malaria cases compared with healthy controls, but lower in children with the protective recessive (TT) genotype. A genetic variant in TLR1 may contribute to the low severe malaria case fatality rates in this region through a reduced pro-inflammatory cellular phenotype.

Peripheral arterial disease and isolated systolic hypertension: the ATTEST study.

Hypertension is a risk factor for cardiovascular (CV) diseases, either coronary artery disease (CAD), peripheral artery disease (PAD) or cerebrovascular disease (CVD). The relationships between those different localizations of CV disease and the haemodynamic features of hypertension have been poorly evaluated in the past. In the ATTEST study, a geographically representative panel of 3020 general practitioners recruited 8316 consecutive patients with CV diseases (PAD, CAD or CVD, alone or in association). Blood pressure, which was not an inclusion criterion, was then measured and related to the different forms of CV diseases. Blood pressure classification involved 20% normotensive subjects, 24% subjects with controlled hypertension, 42% subjects with isolated systolic hypertension and 14% subjects with systolic-diastolic hypertension, all hypertensives with or without antihypertensive therapy. From multiple regression analysis, it appeared that subjects with systolic hypertension were characterized by the presence of PAD, with little or no presence of CAD and/or CVD. Subjects with systolic-diastolic hypertension were characterized by the presence of CAD and/or CVD, but without PAD. Although the former was only influenced by age, dyslipidaemia and diabetes mellitus influenced the latter. This study confirms the high prevalence of hypertension (80%) in a large population of patients with CV diseases selected in primary care. Analysis of different features of hypertension revealed that isolated systolic hypertension was the most prevalent form of hypertension in this treated population. Finally, one of the predominant goals of secondary prevention in subjects with PAD should be the treatment of isolated systolic hypertension.

Glycophorin C delta(exon3) is not associated with protection against severe anaemia in Papua New Guinea.

The high frequencies of mutant haemoglobin and erythrocyte surface proteins in malaria-endemic regions have indicated that polymorphisms in human genes have been under selection pressure by severe malarial disease. Glycophorin C (GYPC) is a major surface erythrocyte protein and also a receptor for the Plasmodium falciparum erythrocyte-binding antigen 140 (EBA-140, also known as BAEBL). There is no binding to GYPC in Gerbich-negative (deletion of exon 3 in GYPC gene: GYPCC delta(exon3)) erythrocytes by EBA-140, hence limiting invasion of erythrocytes by certain P. falciparum lines. The GYPCC delta(exon3) allele reaches high frequencies in two areas of Papua New Guinea (PNG) where malaria is highly endemic. There is, however, no indication that Gerbich negativity protects against malaria-related illness. Using archival blood samples collected from children (<6 years of age) in the Wosera District, East Sepik Province, PNG, we investigated GYPC C delta(exon3) as a possible genetic component of protection against severe malarial anaemia (SMA). The frequency of this human genetic polymorphism was found to be in accordance with previous studies. However, our result showed no association between SMA and GYPC C delta(exon3). Until such an association is clearly shown with severe malaria outcomes, these results raise questions regarding the role of malaria as a selective force for Gerbich negativity.

Assessment of serum ionized magnesium levels in healthy volunteers, in patients with coronary artery disease and/or hypertension and in hypertension alone.

We examined ionized magnesium concentration by blood analysis in patients with hypertonia arterialis, ischemic heart diseases, both of them and in a control group. Slighty lower mean serum ionized magnesium concentration was found in the study group hypertonia arterialis when compared to the control group. In patients both group "B" with coronary artery diseases and group "C" with hypertonia arterialis + ischemic heart diseases, mean serum ionized magnesium concentrations were higher then in the control group, the differences were statistically significant.

Duffy-null promoter heterozygosity reduces DARC expression and abrogates adhesion of the P. vivax ligand required for blood-stage infection.

The Duffy blood group antigen is an essential receptor for Plasmodium vivax entry into erythrocytes in a process mediated by the parasite ligand, the Duffy binding protein (DBP). Recently, individuals living in a malaria endemic region of Papua New Guinea were identified as heterozygous for a new allele conferring Duffy negativity, which results in 50% less Duffy antigen on their erythrocytes. We demonstrate that DBP adherence to erythrocytes is significantly reduced for erythrocytes from heterozygous individuals who carry one Duffy antigen negativity allele. These data provide evidence that emergence of this new allelic form of Duffy negativity is correlated with resistance against vivax malaria.

Search for DNA repair inhibitors: selective binding of nucleic bases-acridine conjugates to a DNA duplex containing an abasic site.

The abasic site is one of the most frequent DNA lesions generated by spontaneous or enzymatic cleavage of the N-glycosidic bond. The abasic site is also an intermediate in the nucleotide and base excision DNA repair. We examined molecules which recognize and cleave DNA at the abasic site with high efficiency. These molecules incorporate in their structure a nucleic base for abasic site recognition, an intercalator for DNA binding, and a polyamino linker for ionic interaction and DNA cleavage. Such compounds, by interfering with abasic sites in DNA, are also inhibitors of DNA repair. In order to better understand the parameters of the interaction, we carried out a UV thermal denaturation study of synthetic oligonucleotides containing the lesion both in the absence and in the presence of the drugs. A similar study was also carried out using the corresponding nonmodified oligonucleotide. The results indicate selective binding of the base-chain-intercalator conjugates to the abasic site containing oligonucleotides.

Serologic responses to recombinant Plasmodium vivax Duffy binding protein in a Colombian village.

The Plasmodium vivax Duffy binding protein (DBP) is essential during merozoite invasion into human erythrocytes. Because of its biological importance, the DBP is also seen to have potential use as a malaria blood-stage vaccine. We have used a soluble recombinant DBP (rDBP) containing the functional ligand domain to assess the natural immunogenicity of DBP in a low-endemic vivax malaria region. Human sera from adult residents from a Colombian village with unstable vivax malaria transmission reacted specifically with the rDBP as determined by ELISA. There was a significant positive correlation between increased antibody response (average, median, and percent positives) and age of patients, although the level of responses did vary considerably in their reactivity to the rDBP from negative to very high level within each age group. These data confirm previous findings on the serologic reactivity of the DBP in exposed populations and that immunologic boosting to the DBP occurs in malaria-endemic regions even with low-level transmission.

[Mobile thrombi of the right heart in pulmonary embolism]. / Thrombus mobiles des cavités droites dans l'embolie pulmonaire.

Systematic transthoracic echocardiography in all cases of pulmonary embolism may demonstrate right heart thrombi. The results of this monocentric series of 28 consecutive cases observed between 1987 and 1996 were analysed. Twenty-four patients were in NYHA Class IV: thirteen were in cardiogenic shock. Echocardiographic signs of acute cor pulmonale were usually observed: 96.3% of patients had right ventricular dilatation, 85.2% paradoxical interventricular septal motion, 88.9% pulmonary hypertension. The thrombus was typical serpentine (27/28 cases) arising from the lower limb veins. Passage into the left heart chambers through a patent foramen ovale was observed in 3 cases. Pulmonary embolism was confirmed in all cases. This is an extreme therapeutic emergency and 13 patients (46.4%) died despite treatment: surgery (7/16), thrombolysis (2/5), heparin (3/4) or interventional radiology (1/3). After the acute phase, the prognosis was generally good, as demonstrated by the 100% survival rate at 28.6 +/- 25 months. This study confirms the gravity of mobile right heart thrombi in pulmonary embolism. The diagnosis is echocardiographic. No significant difference in mortality was observed between the different therapeutic approaches used in this series. The echocardiographic finding of these thrombi is a traditional indication for emergency surgical embolectomy. Thrombolysis is rapid and readily available and seems to provide promising results alone or before surgery. In patients with contraindications to thrombolysis, interventional radiology or simple heparin therapy may be proposed.

[Effects of hormone replacement treatment of menopause on the risk of venous thromboembolic disease]. / Les effets du traitement hormonal substitutif de la ménopause sur le risque de maladie thrombo-embolique veineuse.

Post-menopausal hormone replacement therapy increases the risk of venous thrombo-embolism 2- to 4-fold. The risk is highest in the beginning of the exposure to hormones and disappears rapidly after interruption of treatment. However, the increased risk remains low in absolute value and has to be weighed against coronary artery disease and post-menopausal osteoporosis.

[Doppler echocardiography in the evaluation of left ventricular diastolic function]. / Apport de l'échocardiographie-Doppler à l'évaluation de la fonction diastolique ventriculaire gauche.

It is now well recognized that a disorder of left ventricular filling can be sufficient to account for congestive heart failure. Furthermore, evaluation of heart disease would not be complete if it did not include assessment of left ventricular filling, improvement of which probably ensures better control of the heart disease. An efficient and reliable tool for the study of diastolic function is therefore essential. The authors review the current state of knowledge and the more recent developments in Doppler echocardiography in the evaluation of left ventricular diastolic function. After revising the pathophysiology, the methods of studying ventricular filling are described. The recording technique is described, taking into account recent developments in transthoracic and transoesophageal approaches. This investigation provides parameters allowing semiquantitative estimation of filling pressures (mean left atrial pressure, end-diastolic pressure) and reliable evaluation of overall diastolic performance.

Naturally acquired and vaccine-elicited antibodies block erythrocyte cytoadherence of the Plasmodium vivax Duffy binding protein.

Malaria merozoites require the presence of specific surface receptors on the red blood cell for invasion. Plasmodium vivax, requires the Duffy blood group antigen as an obligate receptor for invasion. The parasite Duffy binding protein (DBP) is the ligand involved in this process, making the DBP a potential vaccine candidate. A preliminary objective was to study whether people exposed to vivax malaria acquire antibodies that have the ability to block erythrocyte cytoadherence to the PvDBP. In comparison, we studied the immunogenicity of various recombinant DBP vaccines and investigated their potential to induct antifunctional antibodies. In order to do so, recombinant proteins to different regions of the putative ectodomain of the DBP and a DNA vaccine were used to immunize laboratory animals. An in vitro cytoadherence assay was used to investigate the presence of antifunctional antibodies in plasmas from people naturally exposed to vivax malaria, as well as in antisera obtained by animal vaccination. Our results showed that human plasma from populations naturally exposed to vivax malaria, as well as antisera obtained by vaccination using recombinant proteins, a DNA vaccine, and a synthetic peptide to DBP, inhibited in vitro binding of human erythrocytes to the DBP ligand domain (DBP(II)) in correlation to their previously measured antibody titer. Our results provide further evidence for the vaccine potential of this essential parasite adhesion molecule.

Phenotypic characterization of Leishmania mexicana pentamidine-resistant promastigotes. Modulation of the resistance during in-vitro developmental life cycle.

Two clones of Leishmania mexicana resistant to 5 microM (LmR5CL2) and 20 microM (LmR20CL1) pentamidine, derived from a parental wild-type clone (LmWTCL3) were selected in vitro using a continuous drug pressure protocol. Both resistant clones expressed a cross-resistance to diminazene aceturate. No differences in their in-vitro infectivity for mouse peritoneal macrophages between wild-type and pentamidine-resistant promastigotes were observed. During these experiments, promastigotes of LmR20CL1 derived from intramacrophagic amastigote forms reverted to the pentamidine-sensitive phenotype, unlike the lower resistant ones. In the same way, when a complete developmental sequence of L. mexicana was achieved in axenic cultures, LmR20CL1 promastigotes derived from axenically growing amastigotes expressed an IC50 value close to the wild-type one, whereas resulting LmR5CL2 promastigotes remained pentamidine resistant. This modulation of the chemoresistance during the developmental life cycle could be significant in the transmission of drug-resistant strains by Phlebotominae as well as in basic research to follow drug resistance during the in-vitro and in-vivo life cycle of Leishmania.

Introduction of a nitroxide group on position 2 of 9-phenoxyacridine: easy access to spin labelled DNA-binding conjugates.

In the search for spin labelled intercalators of general use to construct DNA-binding conjugates, 6-chloro-2-[(1-oxyl-2,2,5,5-tetramethyl- pyrrolin-3-yl)methyloxy]-9-phenoxy-acridine 5, has been prepared. This key-intermediate reacts with amines to give the corresponding labelled 9-amino substituted acridines. Comparative EPR and fluorescence measurements show that the label causes only little modification of the binding properties of acridine.

Pregnancy after myocardial infarction and a coronary artery bypass graft.

The authors report a pregnancy in a 34 year old patient who previously experienced a myocardial infarction. The pregnancy ended at 39 weeks in the birth of a healthy girl weighting 3040 g, by cesarean section under epidural anesthesia. A review of the literature revealed 33 similar cases, 16 of which were adequately documented.

Design of molecules that specifically recognize and cleave apurinic sites in DNA.

We have prepared a series of tailor-made molecules that recognize and cleave DNA at apurinic sites in vitro. These molecules incorporate in their structure different units designed for specific function: an intercalator for DNA binding, a nucleic base for abasic site recognition and a linking chain of variable length and nature (including amino and/or amido functions). The cleavage efficiency of the molecules can be modulated by varying successively the nature of the intercalating agent, the nucleic base and the chain. All molecules bind to native calf thymus DNA with binding constants ranging from 10(4) to 10(6) M-1. Their cleavage activity was determined on plasmid DNA (pBR 322) containing 1.8 AP-sites per DNA-molecule. The minimum requirements for cleavage are the presence of the three units, the intercalator, the nucleic base and at least one amino function in the chain. The most efficient molecules cleave plasmid DNA at nanomolar concentrations. Enzymatic experiments on the termini generated after cleavage of AP-DNA suggest a strand break induced by a beta-elimination reaction. In order to get insight into the mode of action (efficiency, selectivity, interaction), we have used synthetic oligonucleotides containing either a true abasic site at a determined position to analyse the cleavage parameters of the synthetic molecules by HPLC or a chemically stable analog (tetrahydrofuran) of the abasic site for high field 1H NMR spectrometry and footprinting experiments. All results are consistent with a beta-elimination mechanism in which each constituent of the molecule exerts a specific function as indicated in the scheme: DNA targeting, abasic site recognition, phosphate binding and beta-elimination catalysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression and serologic activity of a soluble recombinant Plasmodium vivax Duffy binding protein.

Plasmodium vivax Duffy binding protein (DBP) is a conserved functionally important protein. P. vivax DBP is an asexual blood-stage malaria vaccine candidate because adhesion of P. vivax DBP to its erythrocyte receptor is essential for the parasite to continue development in human blood. We developed a soluble recombinant protein of P. vivax DBP (rDBP) and examined serologic activity to it in residents of a region of high endemicity. This soluble rDBP product contained the cysteine-rich ligand domain and most of the contiguous proline-rich hydrophilic region. rDBP was expressed as a glutathione S-transferase (GST) fusion protein and was isolated from GST by thrombin treatment of the purified fusion protein bound on glutathione agarose beads. P. vivax rDBP was immunogenic in rabbits and induced antibodies that reacted with P. vivax and Plasmodium knowlesi merozoites. Human sera from adult residents of a region of Papua New Guinea where malaria is highly endemic or P. vivax-infected North American residents reacted with rDBP in an immunoblot and an enzyme-linked immunosorbent assay. The reactivity to reduced, denatured P. vivax rDBP and the cross-reactivity with P. knowlesi indicated the presence of immunogenic conserved linear B-cell epitopes. A more extensive serologic survey of Papua New Guinea residents showed that antibody response to P. vivax DBP is common and increases with age, suggesting a possible boosting of the antibody response in some by repeated exposure to P. vivax. A positive humoral response to P. vivax DBP correlated with a significantly higher response to P. vivax MSP-1(19). The natural immunogenicity of this DBP should strengthen its usefulness as a vaccine.